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              OBSERVATIONS
                             ON
                     CERTAIN PARTS
                             OF

THE   ANIMAL   (ECONOMY,
                INCLUSIVE OP SEVERAL PAPERS FHOM
      THE PHILOSOPHICAL TRANSACTIONS, ETC.
JOHN   HUNTER,  F.R.S.
                       OTttti a&otes
                             BY
                RICHARD OWEN, F.R.S.,
        ivnn«, nf the Linnean Geological, and Zoological Societies of London.
                   Philadelphia, Moscow, Erlangen, &c.
Professor of Anatomy and Physiology "and Conservator of the Museum of the Royal College of
                       Surgeons in London.
                      Ptilatfeljjufa:
HAS WELL,  BARRINGTON, AND HAS WELL,
                  293 MARKET STREET.
          NEW  ORLEANS: JOHN J. HASWELL & CO.
                           1840. 
fil
f>r\ <n>\C>
lOtfi.tf.ty    iku„  (o 
TO
      SIR  JOSEPH  BANKS,  Bart.,
         PRESIDENT OF THE ROYAL SOCIETY, ETC., ETC.

  Dear  Sir,
               As the following Observations were made
in the course of those pursuits in which you have so warmly
interested yourself, and promoted with the most friendly
assistance, I should be wanting in gratitude were I not to
address them to you, as a public testimony of the friendship
and esteem with which I am,

                   Dear Sir,
                      Your obliged and
                          Very humble Servant,
                                 JOHN HUNTER.
Leicester Square, Nov. 9, 178G. 
 
A
TREATISE
ON THE
ANIMAL   (ECON  OM  Y.
1. A DESCRIPTION OF THE SITUATION OF THE TES-
    TIS IN THE  FCETUS, WITH  ITS  DESCENT INTO
    THE SCROTUM.

  A discovery in any art not only enriches that with which it is im-
mediately connected, but elucidates all those to which it has any re-
lation.   The knowledge of  the construction of a human  body is
essential to  medicine, therefore every improvement  in anatomy
must throw additional light on that branch of science.  These im-
provements strike more forcibly if they are on subjects quite new
or little  understood ; and this effect is well illustrated by the ad-
vantages which pathology has  derived from the discovery of the
lymphatics being the absorbent system; and likewise by that case
of hernia, where the intestine  lies in contact with the testicle ; which
has been perfectly explained  by the discovery of the original seat
of the testicle being in the abdomen.
  Several years before Haller's Opuscula  Pathologica were pub-
lished, my brother informed me, that in examining the contents of
the abdomen of a child, stillborn, about the seventh or eighth month,
he found both the testicles lying in that cavity, and  mentioned the
observation with some degree of surprise.   By this we are enabled
to account for a circumstance that sometimes happens in the scrotal
hernia, as depending on the  discovery that the testis is formed in
the  abdomen, and which we  could never explain to our satisfaction
till the publication of the Opuscula, to which Dr. Hunter alludes,
(Commentaries, page 72,) in  the following words:
  " In the latter end of the year 1755, when I first had the pleasure
                               5 
42            HUNTER ON THE ANIMAL (ECONOMY.
of reading Baron Haller's observations On the Hernia Congenita,*
it struck my imaginationf that the state of the testis in the foetus,
and its descent from the abdomen into the scrotum, would explain
several things concerning ruptures and the  hydrocele, particularly
that observation which Mr.  Sharp had communicated to me, viz.,
that in  ruptures the intestine is sometimes in contact, with the testis.
I communicated my ideas upon  this subject  to my brother, and
desired that he  would take  every opportunity of learning exactly
the state of the testis before and after birth, and the state of ruptures
in children.  We were both convinced that the examination of those
facts would answer our  expectation, and both recollected having
seen appearances in children that agreed with our supposition, but
saw now that we had neglected  making the proper use of them.
  " In the  course of the winter my brother had several opportunities
of dissecting foetuses of different ages, and of  making some draw-
ings of the parts ;  and all his observations agreed with the ideas I
had  formed of the nature of ruptures, and of the origin of the tunica
vaginalis propria in the foetus.   But  till those  observations were
repeated to  his satisfaction, and were  sufficiently ascertained, he
desired me not to mention the opinion in my lecture ; and therefore,
when treating of the coats of the testis, and of the situation of the
hernial  sac, &c, I  only put in  this  temporary caution, that I was
then speaking of those things as they are commonly in adult bodies,
and  not as they are in the foetus: and at last, when I was conclud-
ing my lectures for that season, in the  end  of April 1756, with a
course of the chirurgical operations, I gave a very general account
of my brother's observations, and showed both the drawing of fig. 2,
which was then finished, and the  subject from which it was made."
  The following observations on this  subject were taken from my
notes, and  published  by Dr. Hunter  in his commentaries to which
I  have added some practical remarks.
  " Until the approach of birth,  the testes of the foetus are lodged
within the  cavity of the abdomen, and may therefore be reckoned
among  the abdominal  viscera.    They  are situated immediately
below the kidneys, on the fore part of the psoae muscles, and by the
side  of the  rectum, where this intestine  is passing  down into  the

  * Alberti HalleH  Opuscul. Pathohg., Lausan. 1755, 8vo., page 53, &c.
  f [Although Haller was in doubt as to the exact period of The descent of the
testis, and in error as to the cause of that phenomenon, yet he accurately describes,
in the original paper here alluded to, the original relations of the gland  to  the
peritoneum and abdominal viscera, and the  formation of the tunica vaginalis, and
thus applies  the facts which he had discovered to the explanation of The disease
he was considering.  " Herniarum, ni fallor, congenitarum modus hinc elucescit,
quo generantur.  Patulus est processus peritonei sub renibus positus, qui  ex-
pectat testem invitatque aperto ostio,  atque eo deorsum  ex solita lege pulso
urgetur, inque scrotum una descendit.  Cum autem his in corporibus testes eodem
cum intestinis sacco omnino contineantur, nihil est singularis sive inexpectati, si
ea in apertum saccum a levi vi depressa fuerint."  (Opusc.  Patholog., p. 56.)  In
this paper there are references to the older authors who had noticed the abdominal
position of the testes in the foetus.] 
          SITUATION OF THE TESTIS IN THE FOETUS.        43

cavity of the pelvis;  for in the foetus, the rectum, which is much
larger in proportion to the capacity of the  pelvis than in the full-
grown subject, lies before the vertebrae lumborum as well as before
the os sacrum.  Indeed the case is pretty much the same with  re-
gard to  all the contents of the pelvis ; that is, their situation is much
higher in the foetus  than  in the  adult.  The sigmoid flexure of the
colon, part  of the  rectum, the  greatest part of the bladder,  the .
fundus uteri, the Fallopian tubes, &c, being placed in  the  foetus
above the hollow of the pelvis in the common or great abdominal
cavity.
  "While the testis remains in the abdomen its shape  or figure
is much the same as in the adult, and its position  or  attitude  the
same as when it is in the scrotum ;  that is, one  end is  placed  up-
wards, the other downwards ; one flat side is to the right, the other
to the left;  and  one edge is turned backwards, the other  forwards;
and the vessels enter the posterior edge alike in both the  foetus and
adult.   As the testis is not so immediately inclosed in the surround-
ing parts while it is in the loins, its position may be a little variable,
and the most natural seems to be when the anterior edge is turned
directly forwards;  but as  the least touch of anything will throw
that edge either to  the right side or to the left, then the flat side of
the testis will  be  turned  forwards.  It is  attached to  the  psoas
muscle  all  along its posterior edge, except just at its  upper ex-
tremity ; and this attachment is formed by  the  peritoneum, which
covers the testis and gives it a smooth surface, in the same manner
as it envelopes the other loose abdominal viscera.
   " The epididymis lies along the outside  of the posterior edge of
the testis, as when  in  the scrotum, but is larger in proportion,  and
adheres backwards to the psoas.  When  the  foetus is very young,
the adhesion of the testis and epididymis to the psoas is very narrow,
and then the testis is more loose, and more projecting;  but as the
foetus advances  in months, the adhesion of the testis  to  the  psoas
becomes broader and tighter.
   " The vessels of  the testis, like those of  most parts of  the  body,
commonly rise from the nearest larger trunks, viz., from the  aorta
and cava, or from the emulgents.
   " The  artery generally rises  from the  fore part of the aorta, a
little  below  the emulgent artery, and often from  the emulgent itself,
especially in  the right side of the  body, which may happen the
rather,  because  the trunk of the aorta is more distant from the right
testis than from the left.   Sometimes, but much more rarely, the
spermatic artery springs  from the phrenic,  or  from that of the
capsula renalis.  Besides the artery which rises from the aorta, or
emulgent, &c, the  testis receives one from the hypogastric artery,
which is  sometimes as large as the  other.  It  runs upwards from
its origin, passing-close to the vas deferens  in its way to the  testis.
The superior spermatic artery sometimes passes before  the  lower
end of the  kidney;  and both  these arteries run  in a  serpentine
direction, making pretty large but gentle turnings.  They are situ- 
44
HUNTER ON THE ANIMAL (ECONOMY.
ated behind the peritoneum, and both run into the posterior edge
of the testis, between the two reflected laminae of that membrane,
much in the same manner as the vessels pass to the  intestines
between the two reflected laminas of the mesocolon or mesentery.
   " The veins of the testis are analogous to its  arteries, but com-
monly change sides with the arteries respecting  their origins from
the emulgents.  The superior spermatic vein, to begin with its
trunk, rises commonly in the  following manner: on the right side,
from the trunk of the vena cava, a little below the emulgent; and
on the left side, from the  left emulgent vein.  The reason of this
difference between the right  and left spermatic vein, no doubt, is
because the  cava is not placed in the middle of the body;  so that
by the rule of ramification which is observed  in  most parts of the
body, the cava is the nearest large vein of the  right  side,  and the
emulgent is the nearest large vein of the left side.  But  the differ-
ence is  inconsiderable;  and  accordingly  we sometimes find the
right spermatic vein coming  from  the  right emulgent  vein; and
several other varieties are produced, which so far as I can observe,
follow no precise rule.   There is  likewise a spermatic vein, which
rises from the internal iliac, and runs up to the testis  with  the in-
ferior spermatic artery.   Both the spermatic veins run behind the
peritoneum with their corresponding arteries, and go into the poste-
rior edge of the testis, where  they are lost in small branches.
  " The nerves of the testis, like  its blood-vessels, come from the
nearest  source; that is, from  the abdominal plexuses  of  the inter-
costal, especially the inferior  mesenteric  plexus.  They run to the
testis, accompanying its  blood-vessels, and are dispersed with them
through its  substance.   The testis, therefore, with respect to its
nerves, may be reckoned an abdominal viscus ; and  this observa-
tion will hold good when applied to the full-grown subject;  as well
as to the foetus; for those branches of the lumbar nerves which are
commonly said to  be sent to the testis, passing through the tendon
of the external oblique muscle, in reality go not to the testis itself,
but to its exterior coverings, and to the scrotum." p. 75.
   The testicle receiving its nerves from  the plexuses of the inter-
costal, accounts for the stomach and intestines sympathizing  so
readily with it and  its particular sensation, and for the effects arising
in the constitution  upon  its being injured.
   " The epididymis begins at the outer and posterior part of the
upper end of the testis, immediately above the entrance of the blood-
vessels, where  it is  thick,  round, and  united to the  testis.  As  it
passes down it becomes a little smaller and more flat, and is only
attached backwards to the testis, or rather indeed to its vessels; for
its anterior edge lies loose  against the side of the testis forwards;
and at its lower end it is again more firmly attached to the body of the
testis, so that in the foetus there is a cavity or pouch formed between
the middle part of the testis and the middle part of the epididymis,
more considerable than  is commonly observed  in full-grown sub-
jects.   As the body grows, the epididymis adheres more closely to 
          SITUATION OF THE TESTIS IN THE FCGTUS.        45

the side of the testis; and its greatest part is made up of one con-
voluted canal, which  becomes larger  in  size and less convoluted
towards the lower end, and at last is manifestly  a single tube run-
ning a little serpentine.  That change happens at the lower end of
the testis, and there the canal takes the name of vas deferens.
   " The vas deferens is a little convoluted or serpentine in its whole
course, but is less so  as it comes  nearer to the bladder; instead of
running upwards from the lower end of the testis, as it does when
the testicle is in the scrotum, while that remains  in the  abdomen, it
runs downwards and inwards in its whole course, so that it  goes on
almost in  the direction of the epididymis, of which it is a continua-
tion. It turns inwards from the lower end of the epididymis, under the
lower end of the testis, and behind the upper end of  a ligament or
gubernaculum testis (which I shall presently describe); then it passes
over the  iliac  vessels,  and over  the  inside of the  psoas   muscle,
somewhat higher than in adult bodies, and at last goes between  the
ureter and bladder towards the basis of the prostate gland."  p. 77.
   In those animals where  the testicles change their situation  the cre-
master  muscle, which should be  named musculus  testis, has two
very different positions in the foetus and in the adult,  the first being
the same  as in  those animals whose testicles remain  through life in
the cavity of the abdomen;  we  must therefore  conclude that  the
same purposes  are answered by this muscle in the foetus as in those
animals.
   The use of this muscle, when the testicle is in the scrotum,  ap-
pears to be evidently that of a suspensory;  for I  find this muscle is
strong in proportion to the size of the testicle and pendulous situation
in other animals.  But what purpose it answers  in the foetus, or in
animals whose testicles remain in the abdomen,  is not easily ima-
gined, there being no apparent reason why such a  muscle should
exist.*
   The cremaster, or  musculus testis, appears to be composed of the
lower fibres of the obliquus internus and transversalis muscles in the
foetus, turning upwards, and spreading upon the anterior surface of
the gubernaculum, immediately under  the peritoneum; it appears to
be lost on  the peritoneum, a little way from the testicle. This,
although  now  inverted, is more  evidently seen  in   adult  subjects
who have had a hydrocele or rupture;  in  such  cases  the  muscle
becomes stronger than usual, and  its fibres can be traced spreading
on the tunica vaginalis, and seem at last to be lost upon it, near to
the lower end of the body of the testicle.
   The nerves which  supply this muscle are probably branches from

   * [The cremaster does not in fact exist in the true testiconda, as the elephant, hyrax,
seal, walrus, the  Cetaceous and Monotrematous Mammalia; in these the testes
are merely supported by  their vessels and a fold of peritoneum analogous to the
broad ligaments of the uterus and ovaries ; but when the cremaster is  met with
in apparent testiconda it is always in relation to a partial or temporary escape of
the testis from the abdomen, as in bats and most insectivorous Ferae, and in many
of the Glires, as the rats, squirrels, beaver, porcupine, &c] 
46
HUNTER ON THE ANIMAL (ECONOMY.
the nerves of the obliquus internus and transversals muscles ;* tor
the same cause which throws  the  abdominal muscles into action
produces a similar effect on the musculus testis; which circumstance
appears to be most  remarkable  in  the young subject.   When we
cough or act with  the  abdominal muscles, we find the testicles to
be drawn up; the musculus testis and abdominal muscles taking on
the same action from the same  cause.f
  " At this time of  life  the testis is connected in a very  particular
manner with the parietes  of  the  abdomen, at that place where in
adult bodies the spermatic vessels pass out, and likewise with the
scrotum.  This  connexion is by means of a substance which runs
down from the  lower end  of the testis to the scrotum, and which at
present I shall call the  ligament, or gubernaculum testis, because
it connects the  testis with the  scrotum,  and seems to  direct its
course through  the  rings  of the abdominal muscles.   It is of  a
pyramidal form ; its large bulbous head is  upwards, and fixed to the
lower end of the testis and epididymis, and  its  lower  and slender
extremity is lost in the cellular  membrane  of  the scrotum.  The
upper part of this ligament is within the abdomen, before the psoas,
reaching from the testis to the groin, or to where the testicle  is to
pass out of the abdomen;  whence the ligament  runs down into the
scrotum, precisely in the same manner as the spermatic vessels pass
down in adult bodies, and is there  lost.  The  lower part of the
round ligament of the uterus in  a foetus very much resembles this
ligament of the testis, and may be plainly traced down  into the
labium, where it is imperceptibly lost.   That part of the ligamentum
testis which is within the abdomen  is  covered  by the  peritoneum
all round except at  its posterior  part, which is  contiguous  to the
psoas, and connected with it by the reflected peritoneum and by the
cellular membrane.   It  is  hard to say what is the structure or com-
position of this ligament;  it is  certainly vascular  and fibrous, and
the fibres run in the direction of the ligament itself, which is covered
by the fibres of the cremaster or musculus  testis, placed immediately
behind the peritoneum.  This circumstance is not easily ascertained
in the human subject; but is  very evident in  other animals, more
especially in those whose  testicles remain in the cavity of the abdo-
men after the animal is  full grown.
  " In the hedgehog the testis continue through life to  be lodged
within the abdomen, in the same situation as in the human foetus;

  * [The first lumbar nerve, which gives many small branches to the transversalis
abdominis, sends off a branch which, in conjunction with smaller branches from
the second lumbar nerve, forms the ' external spermatic nerve'  from which the
cremaster is supplied.]
  f [As the cremaster is supplied  from common  or spinal nerves, it is not sur-
prising that it should in some  cases, like the occipito-frontalis muscle, be under
the control of the will.   Mr. Marshall observes, in his work On Recruits, " Some
individuals have the voluntary power of contracting and relaxing the cremaster
muscle : others can elevate the testicle on one side but not on the other; and 1
have seen a few persons who could voluntarily raise a testicle, but had not the
power of letting it return into the scrotum."] 
SITUATION OF THE TESTIS IN THE FOETUS.        47
and they are fastened by the same kind of ligament to the inside of
the parietes of the abdomen at the  groin.   Now in  that animal I
find that the lowermost fibres  of the internal oblique muscle, which
constitute the cremaster, are turned inwards at the place where the
spermatic vessels come out in other animals, making a smooth edge
or lip by their inversion, and that then they mount up on the  liga-
ment to the  lower end of the testis.*   Sometimes in  the  human
body, and in many other animals, and very often in sheep, the testes
do not descend from the cavity of the abdomen till late in  life, or
never at all.  In the ram, when the testis is  come down into the
scrotum, the cremaster is a very strong muscle; and, though  it be
placed more inwards at its beginning, it passes down pretty much
as it does in the human body, and is lost on the outside of the tunica
vaginalis;  but in  the  ram, whose  testis still remains suspended in
the abdominal cavity, I find that the cremaster still exists, though
it is a weaker muscle;  and instead of passing downwards, as in the
former case, it turns inwards and upwards, and is lost in the  peri-
toneum that covers the ligament which attaches  the testis to the
parietes of the abdomen, which in this state of the  animal is  about
an inch and a half in length.   In the human foetus, while the  testis
is retained in the  cavity of the abdomen, the cremaster is so slender
that I cannot trace it to my own satisfaction, either turning up
towards the  testis or turning down towards the  scrotum.   Yet,
from analogy, we may  conclude that it passes up   to the testicle;
since in  the adult we find it  inserted  or lost  on  the  lower part
of  the  tunica  vaginalis, in  the  same manner   as  in the  adult
quadruped.t
  " The peritoneum, which covers the  testis and  its  ligament or
gubernaculum, is firmly united to the surfaces of these two bodies;
but all around, to wit, on the kidney, the psoas, the iliacus, internus,
and the lower part of the  abdominal  muscles,  that membrane

  * [The apparent anomaly of this, as of almost  every other natural structure,
disappears when we  attain  the requisite  amount of knowledge respecting the
conditions under which it exists. The testes of the hedgehog, like those  of the
mole, (see p. 66,) are subject to remarkable periodical enlargement at the season
of copulation, when  they are drawn down  by the cremaster to the external ring.
In this situation they are favourably placed to be affected by the expulsive actions
of the diaphragm and abdominal muscles, by which they aTe eventually protruded
and the cremasteric  pouch  is  inverted.  As the testes  diminish in size their
muscular covering contracts upon them and returns them into the abdomen.]
  \ [By such a pre-arrangement of the relations of the cremaster to the testis the
necessity for the latter to overcome in its passage outwards the resistance  of the
inferior fibres of the transversalis abdominis and obliquus internus is obviated.
It cannot reasonably  be doubted that the cremaster exists, as such, in the human
foetus prior to the descent of the testis, since it is indubitably present and attached
to an abdominal testis in animals where no mechanical cause  could have operated
to produce this disposition of the  muscular  fibres.  Besides, the use  of the
cremaster as a supporter and compressor of the testis is obviously too important
for such a connexion to have been allowed  to result from the gland accidentally,
as it were, pushing before it some opposing fibres of the abdominal muscles in
its progress outwards, as Carus imagines.  See his Comparative Anatomy, by
Gore, vol. ii., p. 347.] 
48
HUNTER ON THE ANIMAL CECONOMY.
adheres very loosely to all the surfaces which it  covers.  Where
the peritoneum is continued or reflected from the abdominal muscles
to the ligament of the testis it passes first downwards a little way,
as if going out of the abdomen, and then upwards, so as to cover
more of the ligament than is  within the cavity of the abdomen.  At
this place  the peritoneum is very loose, thin in its substance, and 01
a tender gelatinous texture; but all around the passage of that liga-
ment the peritoneum is considerably tighter, thicker, and of a more
firm texture.  When the abdominal muscles are pulled up so as to
tighten and stretch  the peritoneum  this membrane remains loose at
the passage of the ligament while it is braced or tight all around;
and in that case the tight part forms a kind of border or edge around
the loose double part of the peritoneum,  where the testis is  after-
wards to pass.  This loose part of the peritoneum, like the  intro-
suscepted  gut, may, by drawing the testis upwards, be pulled  up
into the abdomen,  and made tight, and then  there is no appear-
ance of an aperture or  passage  down towards the scrotum;  but
when the scrotum and ligament are drawn downwards, the loose
doubled part of the peritoneum descends with the ligament, and
then there is an aperture from the cavity  of the abdomen all around
the fore part of the ligament, which seems  ready to receive the
testis.  This aperture  becomes larger when the testis descends
lower, as if the pyramidal or wedge-like  ligament was first  drawn
down in order not only to direct but  to  make room for the testis
which must follow  it.   In some foetuses I have found  the aperture
so large that I could push the testis into  it as far as  the tendon of
the external oblique muscle.
   " From this original situation within the abdomen the testis after-
wards descends to its destined station in the scrotum; but it becomes
difficult to ascertain the precise time of this  descent, as we hardly
ever know the exact age of our subject.  According to the observa-
tions which I  have  made,  it seems  to happen sooner in some
instances  than in others;  but  generally about the eighth  month.
In the seventh month I have commonly found the testis in the abdo-
men; and in the ninth I have as  commonly found it in the upper
part of the scrotum.  The descent being thus  early, and the passage
being almost immediately closed,  are the principal means of pre-
venting the hernia congenita.
   " At the before-mentioned  period the testis  moves downwards till
its lower extremity comes into contact  with  the lower part of the
abdominal parietes:  when the upper part of the ligament, which
hitherto was within the abdomen, has sunk downwards, it lies in the
passage from the abdomen to  the scrotum, and in  that which is
afterwards to  receive the testis.   As the testicle passes out it in
 some degree  inverts  the  situation of the ligament passing down
 beyond it; what was the anterior surface of  the  ligament while in
 the abdomen, now becoming posterior  and  composing the lower
 and anterior part of the  tunica vaginalis, on which the musculus
 testis is lost.   This is more evident in those animals whose testicles 
          SITUATION OF THE TESTIS IN THE FCETUS.        49

can readily be made to pass up from the scrotum to the abdomen.
The place where the ligament is most  confined, and where the
testis meets with  most obstruction in its descent, is the ring in the
tendon of the external oblique muscle; and accordingly I think we
see more men with one  testis or both lodged immediately within
the tendon of that muscle than who have one or  both still included
in the cavity of the abdomen, which I shall take notice of hereafter.
   " After the testis has got quite through the tendon of the external
oblique muscle it may  be considered as now in a way easily to
acquire its determined  station,  though it commonly remains  for
some time by the side of the penis,* and only by degrees descends
to the bottom of the scrotum; and when the testis has descended
entirely into the scrotum its ligament is still connected  with it, and
lies immediately under it, but is shortened and compressed.
   " Having now given an account of the  original  situation of  the
testes, of the time of their descent from  the abdomen, and of  the
route which  they take in their passage  to the  scrotum, I shall in
the next place describe the manner in which they carry down  the
peritoneum with them, and then explain how that membrane forms
the tunica vaginalis propria in common, and the sac of the hernia
congenita in some bodies.
   " While the testis is descending, and even when it has passed into
the scrotum, it is still  covered  by the peritoneum, exactly in  the
same manner as when within the abdomen, the spermatic vessels
running  down  behind the peritoneum there as  they did when  the
testis lay before the psoas muscle: that  lamella of the peritoneum
is united behind with the testis, the  epididymis,  and the spermatic
vessels, as it  was in the loins, and likewise with the vas deferens;
but the testis is fixed posteriorly to the parts against which it rests,
being unconnected and  loose forwards, as while it remained in  the
abdomen.  In coming down, the testis brings the peritoneum with
it; and  the elongation of that membrane, though in some circum-
stances it be  like a common hernial sac, yet in  others is very dif-
ferent.   If we can imagine a common hernial sac reaching to  the
bottom of the scrotum, covered by the cremaster muscle; and that
the  posterior half of the  sac covers and is united with the testis,
epididymis, spermatic vessels, and vas deferens;  and that the ante-
rior half of  the sac  lies loose before all those parts, it will give a
perfect idea of the state of the peritoneum, and of the  testis when
it comes first down into the scrotum.  The testis  therefore, in its
descent, does  not fall loose, like the intestine or epiploon, into the
elongation of the peritoneum, but slides down from the loins, carry-
ing the peritoneum with it;  and both that and the peritoneum con-
tinue to adhere, by  the  cellular  membrane, to the parts behind
them, as they did when in the loins.   This is a circumstance which

   * [This is the permanent situation of the testis in the Quadrumana, in which
also, as in the human foetus at the period above mentioned, the tunica vaginalis
communicates witb the abdominal cavity.]                             *
                             6 
50
HUNTER ON THE ANIMAL (ECONOMY.
I think may be easily understood, and yet that does not appear to
be  the  case; for I find  students very generally puzzled  with it,
imagining that when the testis comes first down  it should be loose
all round, like a piece of the  gut or epiploon in a common hernia.
The ductility of the peritoneum, and its very loose connexion by a
slight cellular membrane  to  psoas muscle, and all the other parts
around  the  testis, are circumstances which favour its elongation
and descent into the scrotum  with the testis."
  " This peculiarity of descent often takes place in some of the intes-
tines; but can only happen  in those which have adhesions to  the
loins.  This I suspect is only to be met with in old ruptures, never
happening at  the  first formation of  the hernial sac, in which  the
intestine lies ; and, I should suppose, could only form very gradually.
The caecum has sometimes been found to have descended  into the
scrotum, and to have brought along  with it the adhesions through
its whole course.   The  same thing  has happened to the  sigmoid
flexure  of the  colon ; and I  have found the whole of  it in the left
side of the scrotum, with its adhesions brought down from the loins.
Such herniae cannot be  reduced; and  in  case  of strangulation,
which  may  be brought  on by a fresh portion of  intestine coming
down, are not to be treated in the common way :  the sac should not
be opened, but the stricture divided, and the newly protruded part
reduced.
  " It is plain, from this description, that the cavity of the  bag, or
of the elongation of the peritoneum, which contains the testis in the
scrotum, must at first communicate with the general cavity of the
abdomen by an aperture at the inside of the groin.  That aperture
has exactly the appearance of a common hernial sac ; the spermatic
vessels  and vas deferens  lie  immediately behind it, and  a probe
passes readily through it from the general cavity of the abdomen
down ;to the bottom of the scrotum.  And if this process of the
peritoneum be laid open through its whole length on the fore part,
it will be plainly seen to be a continuation of the peritoneum:  the
testis and epididymis will appear at the lower part of it, and the
spermatic vessels and the vas deferens will be found covered by the
posterior part of the bag in their whole course from the groin to the
testis.
  " Thus it  is in the human body when the testis is recently come
down: and  thus  it is, and continues ,to be through life, in every
quadruped which I have examined where the testis is in the scrotum;
but in the human body the communication between the sac and the
cavity of the abdomen  is soon cut off.   Indeed  I believe  that the
upper part of the sac  naturally begins to contract as soon as the
testis has passed through the muscles;  which opinion  is grounded
on the following observation.   In an instance where, from  the age
of the foetus and from every other mark, it was  probable that the
testis was very recently come down, and yet the upper part of the
sac  was very narrow,  I  pushed the testis upwards, in order to
see  if it could be returned.  The attachments of the testis easily
admitted of its ascent, and  so  did  the aperture in  the  tendon 
           SITUATION OF THE  TESTIS IN THE FCETUS.         51

of the external oblique muscle ;  but the orifice and upper end of the
sac would not by any means admit of the testis being passed quite
up into the abdomen.  However this may be, the upper end of the
sac certainly contracts and unites first, and is quite closed in a very
short space of time, for  it is seldom that any aperture remains in a
child born at its full time; and this contraction and union is con-
tinued downwards till it  comes near the testicle, where this disposi-
tion does not exist, leaving the  lower part of the sac open or loose
through  life even  in the  human  subject,  and  forming the  tunica
testis vaginalis propria,  the  common  seat of a hydrocele.   Many
cases of hydrocele in  children  seem to  prove that the progress of
this  contraction  and union is  downwards; for in them the water
commonly extends higher up the chord than in the adult, except in
those of a considerable size;  yet in some children this union seems
not  to take  place regularly, being interrupted in the middle, and
producing a  hydrocele of the chord which neither communicates
with the abdomen nor tunica vaginalis testis.  The contraction and
obliteration of the passage appears to be a peculiar operation of
Nature, depending upon  steady  and uniform principles, and  not  the
consequence  of  inflammation nor of anything that is accidental;
and therefore, if it is not accomplished at the proper time, the diffi-
culty of bringing about  a union of the parts is much greater, as is
seen in  children who have had the sac kept open by a turn of the
intestine  falling down in  the scrotum immediately after the testis.
This looks  as if Nature, from  being  balked when she was in the
humour  to  do her  work, would  not or could not so easily do it
afterwards.  I shall readily grant that what has been advanced here
as a proof of the doctrine may be explained upon other principles;
but this at least is certain, that the closing of the mouth and of the
neck of the  sac is peculiar  to the human species ;*  and we must
suppose the final intention to be the prevention of ruptures, to which
men are so  much more  liable than beasts from their erect state of
body."
   In some cases the aperture of the sac is not entirely closed, allow-
ing a fluid to pass down and form a hydrocele;  which fluid, upon
pressure, can be squeezed back into the belly; and instances of this
kind sometimes giving the idea of a gut  being protruded, make it
difficult to determine the exact  nature of the case.
   " What is the immediate cause of the descent of  the testis from

  * [The chimpanzee, or African orang-utan (Simia Troglodytes, Blum.), which
of all mammalia approximates most  closely to the human structure, resembles
man in the early obliterations of the canal which leads from the peritoneal cavity
to the tunica vaginalis. In the Indian orang (Simia Satyrus, Linn.), on the con-
trary, the  canal of communication is  free. This difference of structure relates
doubtless  to the different conditions of the lower extremities in these otherwise
closely allied quadrumana : in the chimpanzee they are proportionally larger and
stronger, the leg can be more extended on the thigh, and the hip-joint is strength-
ened by a ligamentum teres; in the orang, on the contrary, the lower  limbs are
freely developed as organs of support, but have great extent of motion, the hip-
joint being, like the shoulder-joint, without a round ligament.] 
52
HUNTER ON THE ANIMAL CECONOMY.
the loins to the scrotum?   It is evident that it cannot be the com-
pressive force of respiration ; because the testis is commonly in tn
scrotum before the child has breathed, that is, the effect has been pro-
duced before the supposed  cause has existed.   Is the  testis pulled
down by the cremaster muscle ?   I can hardly suppose that it is ;
because, if that was the case, I see no reason why it should not ta£e
place in the hedgehog, as well as in other quadrupeds ;  and it the
musculus testis had this power it could  not bring it lower than the
ring of the  muscle.
  " Why do the testes take their blood-vessels from  such distant
trunks?  Those physiologists who  have puzzled  themselves about
the solution of this question have not  considered  that in the first
formation of the body the testes are situated not in the scrotum but
immediately below the kidneys; and  that  therefore  it was  very
natural that their blood-vessels should rise nearly in the same manner
as those of  the kidneys, but a  little lower.*   The great length of
the spermatic  vessels in the adult  body will no  doubt occasion a
more languid circulation,  which we may suppose was the intention
of nature.
  " The situation of the testis in the foetus may likewise account
for the contrary directions of the epididymis and of the vas deferens
in adult bodies, though these two in reality make only one excretory
canal.  In the fcetus the epididymis begins  at the upper  end of the
testis;  and  it is natural, considering it is  an excretory tube, that it
should run downwards.   And it is as  natural that the  rest of the
tube, which is called vas  deferens, should  turn inwards  at the
lower end of the testis, because that is  its  most direct  course to
the neck of the bladder.   Thus we  see that in the fcetus the excre-
tory duct is always passing downwards.   But the testis is directed
in its descent  by the  gubernaculum, w7hich  is firmly fixed to the
lower parts of the testis and epididymis,  and to  the  beginning of

  * [The singular course of the recurrent nerves results from a similar mechani-
cal cause.  At the period when  the rudimentary larynx first derives its nerves
from the par vagum, the head and trunk are not separated by a neck, the trachea
is not formed, the heart is situated near the base of the cranium, and the  branchial
arteries given off from the bulb of the then single artery pass above the nerves
in question.  As the anterior extremities bud forth, the brachial plexuses are de-
veloped and the neck  begins to elongate;  then the rings of the trachea are suc-
cessively added, and the larynx, which before was  close to the heart,  is carried
upward, and  the recurrent nerves, restrained by their relations to the arteries,
which are now converted into  the subclavian on  the right side, and aortic arch
on the left, become proportionately elongated.  The recurrent course of the branch
Of the dental nerve which supplies the pulp of the incisor in the porcupine and
other Rodentia is explicable on a similar principle, the relative position of the
pulp to the origin of its nerve being gradually changed by the growth of the jaw
and  extension of the  tooth.   See the preparation  illustrating this fact  in the
Gallery of the Hunterian Museum, No. 357 b.
   It is  scarcely necessary to observe that the above mechanical explanation of
the course of the recurrent nerves leaves the question of the final cause as open
as before.  Mr. Hunter, after giving the physical cause of the course of the
spermatic artery, next proceeds  to inquire into the intention of Nature with re-
ference to that peculiarity.] 
          SITUATION OF THE TESTIS IN THE FCETUS.        53

the vas deferens, and thence must keep those parts invariably in
their situation with respect to one  another:  and therefore in pro-
portion as the testis descends the vas deferens must ascend from the
lower end of the testis; and it must, from the passage through the
abdominal muscles down to the testis, run parallel with the spermatic
vessels.
   " The testis, its coats, and the spermatic chord are so often con-
cerned in some of the most  important diseases and operations of
surgery, particularly in the bubonocele and  hydrocele, that their
structure has been examined and described by the surgeons, as
well as by the anatomists, of every age.  Yet the descriptions of
the clearest and  best writers upon  the  subject differ so much from
one another, and many of them differ so much from what is obvious
and demonstrable by dissection, as to render it difficult to account
for such a  variety of opinions.  The very  different state of the
parts in the quadruped  and in  the  human body, no doubt, must
have occasioned  error and confusion  among the writers of more
ancient times, when the parts of the human  body were described
from dissections  and observations made  principally upon brutes:
and the structure of parts, which are peculiar to the foetus, having
been imperfectly understood, we may suppose, has likewise con-
tributed to  cause perplexity and  contradiction among authors.
   " Baron  Haller, in his Opuscula Pathologica, has observed that
in infants the intestine sometimes falls down into the scrotum after
the testis, or along with it, and  occasions what he calls the hernia
congenita.   In such a case the hernial sac is formed before the in-
testine falls down, as that ingenious anatomist has observed.  There
are, besides, two circumstances  peculiar to a rupture of  this kind,
the intestine being always in immediate contact with the testis, and
there being no tunica vaginalis propria testis.   The structure of the
parts in a fcetus  explains in the most satisfactory manner both these
circumstances, however extraordinary they must appear to a man
who has only been accustomed to view the  parts in subjects of a
more advanced age; and  indeed it is so clear that it needs no illus-
tration.  It  should be observed, however, that the hernia congenita
may happen not only by the intestine falling down  to  the testis
before  the aperture of the sac be shut up, but  perhaps afterwards;
for when the sac has  been but recently closed  it seems possible
enough that violence may open it again.
   " It  must likewise be  obvious  to every anatomist, who examines
the state of the testis in children of different  ages, that the mouth
and neck only of the sac close up, and that  the lower part of the
sac remains loose around  the testis, and makes the tunica vaginalis
propria. Whence it is plain that this tunic was originally a part
of the elongated peritoneum; and, as it is  undoubtedly the seat of
the true hydrocele, it is  also plain that the hernia congenita and the
true hydrocele cannot exist together in the same side of the scrotum.
For when there is a hernia congenita there is no other  cavity than
                               6* 
54
HUNTER ON THE ANIMAL (ECONOMY.
that of the  hernial sac; and  that cavity communicates with the
general cavity of the abdomen.
  " The observations contained in the two last paragraphs occurred
to my brother upon reading Baron Haller's Opuscula Pathologica,
and  gave rise  to my inquiries upon  this subject."—Medical Com-
mentaries, part  i., p. 83.
  Having explained the situation of the testicles in the fcetus, and
their descent, with the circumstances attending it, I shall  next con-
sider the cases  in  which the  change takes  place, in one or both
testicles, later than the usual or natural time.   And having re-
marked the consequences of this  descent at so late  a period, I shall
take notice of those instances in  which the testicles never pass out
of the abdomen.
  I have said that the early descent of the testicles, and closing of
the mouth of the  sac, by usually happening before birth, prevent
likewise the descent of any  part of  the abdominal viscera; but
when the testicles remain in their first situation beyond this period
these advantages are lost; a part of the  intestines  or epiploon
being, under these circumstances, liable  to  descend along  with
them.
  The first or natural process, in some instances,  not having been
begun, or having been interrupted  before birth, it becomes afterwards
very uncertain when the descent  will be completed: yet I think the
completion most frequently happens between the years of two and
ten, while the person is young and growing, being seldom delayed
beyond the age of puberty.
  It is not easy to ascertain the cause of this failure in the descent
of the testicle; but I am inclined  to suspect that the fault originates
in the testicles  themselves.  This  however is certain, that the tes-
ticle which has  completed its  descent is the largest, which is more
evident in the quadruped than in  the human subject; as in these we
can have an opportunity of examining the parts when we please,
and can  determine how small in comparison with the other that
testicle is which has exceeded the usual time of coming down; it
never descends  so low as the  other.
  The descent of that testicle is  very slow which  is not completed
before  birth, often requiring years for that purpose; and it  some-
times never  reaches the  scrotum, especially the  lower part of it.
There is oftener I believe an  inequality in the situation of the two
testicles than is  commonly imagined, being seldom equally low in
the scrotum; and I am of opinion that the lowest is the most vigorous,
having taken the lead readily, and come to its place at once.   The
part where  it meets with the greatest difficulty in  its descent is in
the division of the tendon of the external oblique muscle called the
ring.
   How far  an erect position  of  body, the action of the abdominal
muscles, and the effect produced  upon the contents  of the abdomen
in breathing may contribute  mechanically to the descent of the
testicles when the  natural operations of the animal ceconomy have 
SITUATION OF THE TESTIS IN THE FCETUS.        55
failed, I will  not pretend to decide; but when we see  these com-
bined actions producing an unnatural descent of  a portion of intes-
tine, we may conceive that they are likewise capable of contribu-
ting to the descent of the testicle.
  When  the testicle  has remained in the cavityof the abdomen
beyond the usual time, it is  impossible to say whether the disposition
for closing up the passage, after it has passed out, is in any degree
lost or not; but when it comes down after birth,  we can easily sup-
pose a portion of intestine or epiploon is more likely to descend and
prevent the closing of the  mouth of the sac, than before the child
was born, when certain actions had  not taken place.   We should
therefore  watch this descent  of the testicle, and  endeavour, by art,
to procure that union which  the natural powers  are either not dis-
posed to perform, or are prevented from completing by the descent
of  other parts; but  art should  not be used too soon, nor till the
testicle has got a little way below the ring.  As this progress is very
slow, especially when the  testicle is creeping through  the ring, a
doubt often arises whether  it is better entirely to prevent its passage,
or  to assist it by exercise  or other means;  and  it would certainly
be  the best practice  to assist  it, if that could be done effectually and
safely.  When it has got upon the outside of the tendon  it can in
general be easily pushed up  again into the abdomen; and in these
two situations it'will sometimes play backwards and  forwards for
several years, without ever coming low enough to allow of the use
of  artificial  means to hinder its descent, or to  prevent a rupture.
In  this case it becomes difficult to determine what should be done;
but, from what I have seen, I should be inclined to wait the descent,
giving  it every assistance in my power.  Indeed, in  all cases  I
would advise waiting with patience,  for in most of those which I
have seen, years have elapsed from the first appearance of the tes-
ticle under the ring of the  abdominal muscle before it has reached
that situation in which we may safely apply a truss.  I never have
perceived that any inconvenience has arisen from waiting, and the
danger, if there is any, may be in some degree avoided.  I have
 always recommended moderate, not violent exercise.
    When  the testicle has got some way below the ring, then the case
 is to be treated as an inguinal hernia, and a truss applied upon the
 ring;  taking care that the testicle is not injured by it: but as this
 generally happens at too early a period for the  patients themselves
 to be capable of attending  to  it, the surgeon  who  is employed
 should be very attentive, and those in whose immediate care they
 are, particularly watchful, that no inconvenience is produced by the
 truss.  I have, however, known a rupture happen in a man thirty-
 years old, where the testicle had not even got into the ring.  In such
 a  case I think a truss should  be immediately  applied; for if it is
 thought advisable to prevent the testicle from coming down, a truss
 is  equally adapted for that purpose, as for hindering the descent of
 an intestine  where there is an hernial sac.
    It sometimes  happens that one of the testicles  remains in the 
56
HUNTER ON THE ANIMAL (ECONOMY.
cavity of the abdomen through life, never acquiring the disposition
to change its  situation; therefore the  person naturally concludes
that he has only one testicle ; and it can only be known that he had
two by an examination of these parts after death; it is, however,
possible that in some instances one may be wanting; but, if we are
to reason from analogy, we  must suppose  this to  be  a very rare
case;  for it is a very common circumstance, that many quadrupeds
have only one  testicle in the scrotum; and in  such as are killed for
food, and from that  circumstance  come more particularly  u"der
observation, if this peculiarity has been noticed, we in general find
the other testicle in  the cavity of the  abdomen; though in  some
instances they are both found lying in that cavity.
  When one or  both  testicles  remain  through life in the belly, I
believe that they are exceedingly imperfect, and probably incapable
of performing  their natural functions, and  that this  imperfection
prevents the  disposition for descent from taking place.   That they
are more defective  than even those which are  late in passing  to the
scrotum, is to be inferred from what is very evident in quadrupeds,
the testicle that has reached the scrotum being in them considera-
bly larger than  the  one which remains in  the  abdomen.  It is
probable that this peculiarity is a step towards the  hermaphrodite,
the testicle being seldom  well formed.   I  have only seen one case
in the  human subject  where  both testicles continued in the  abdo-
men; this proved an exception  to the above observation, since we
are led to conclude that they were perfectly formed, as the persons
had all the powers and passions of a man.*   In such cases nothing
is to be done by art, as it  is not possible to  give the  testicles the
stimulus of perfection, which I believe  is necessary to make them
assume the disposition requisite for their descent ;f and the ring of
the external oblique muscle is perhaps less liable, in such instances,
to allow  a portion of intestine to push down,  than where the testi-
cles  have passed through it; and  such persons may probably  be
more secure from accidents of this kind than if they had been more
perfectly formed.
  The testicle, in changing its situation, does not always preserve
a proper course towards the scrotum, there being instances  of  its

  *  [It seems remarkable, that with this experience Mr. Hunter should have
formed,  from inconclusive  analogy, and promulgated an  opinion  tending to
occasion so much unhappiness as that which attributes exceeding imperfection,
and probable incapacity of performing their natural functions, to testes which in
the human subject are retained within the abdomen.   That there is nothing in
such a situation which necessarily tends to impair their efficiency, is evident, from
the number of animals in  which  they constantly form part of the abdominal
viscera.  And in  those in which the testes naturally pass into a scrotum, their
continuance in  the  abdomen, according to our author's  own observation, is
accompanied only with a difference of size or shape ; now we may readily sup-
pose that this may influence the quantity, but not  necessarily the quality of the
secretion.]
  f [The case described in the paper on the vesiculae seminales, p. 61, seems to
offer an exception to this rule; the right testicle had passed through the external
ring, although the vas deferens was impervious.] 
SITUATION OF THE TESTIS IN THE FCETUS.        57
taking another direction, and descending into the perinaeum.  How
this is brought about is  difficult  to say; it may possibly be occa-
sioned by something unusual in the construction of the scrotum ; or,
more probably, by a peculiarity in that of the perinaeum itself; for
it is  not easy to  imagine how the  testicle could  make its way to
the parts about the perinaeum if these were in a  perfectly natural
state.
  The first instance of this kind  that occurred to me was the child
of a shopkeeper in Oxford-street, which I visited,  in company with
Dr.  Garthshore, about  the year 1775; but what became of the
patient afterwards I do  not know.  I have lately been consulted in
a similar case, by Mr. Hunt, a surgeon, at Burford in Oxfordshire,
whose apprehensions of what may be the consequences of a testicle
remaining in the perinaeum appear to be well founded.  The  most
effe'ctual method of obviating these will probably  be to support the
testicle in a situation near the groin, by the application of a bandage
that may hinder its descent into  the perinaeum, by which the parts
may be  in  time so consolidated as to retain it by  the side of the
scrotum.

     " Dear Sir,
   "  I  take the liberty of writing to you, in consequence of having
met with a lusus naturae of a peculiar kind, in the son of a man in
this  neighbourhood.
   " The boy is about twelve months old : his right testicle is situated
about an inch below the termination of the scrotum, and half an
inch on the right side of the  centre of the rapha  perinaei, where a
kind of pouch is formed of the common integuments, without the least
rugous or scrotal appearance on its surface.   It is perfectly detached
from the scrotum ; nor can the testis or  spermatic process  be at
any time felt in  any part of the scrotum, though I  can readily make
the  testis pass from its situation quite up into the groin; but immedi-
 ately upon removing my hand the testis falls down into its pouch;
and I can  trace the spermatic chord from the body of the testis up
to the ring, running about a fourth of  an  inch on the right side of
the scrotum. The scrotum on each side appears perfectly formed, and
 the left testis is in situ naturali.   Now, sir, as I conceive this peculiar
 conformation maybe attended with great inconvenience to the child
 when he comes to ride on horseback, and on many other occasions,
 I beg leave to request your  opinion upon it, with respect to  what
 ought to  be done to  prevent accidents, which must, if left in its
 present situation, often  occur.
   " Burford, Oxfordshire.         [Signed]   Thomas Hunt." 
5$           HUNTER ON THE ANIMAL (ECONOMY.
2. OBSERVATIONS  ON  THE GLANDS  SITUATED  BE-
     TWEEN  THE  RECTUM  AND BLADDER, CALLED
     VESICULAE SEMINALES.

   Those bags, in the male of some animals, which are situated be-
tween the bladder and rectum, and commonly called ' vesiculae s^™1"
nales,'  have been considered as reservoirs of the semen secreted by
the testicles, in the same manner as the gall-bladder is supposed to
be a reservoir of the bile.  Physiologists must have been led to
form this opinion from  observing that in  the  human subject their
ducts communicate with the vasa deferentia before their termination
in the urethra.   This communication was  supposed to  allow the
semen, when not immediately wanted, to pass  into  the bags from
the vasa deferentia by a species of regurgitation.   But more accurate
observations respecting their structure and contents in the human
subject, and on  corresponding  parts in other  animals supposed to
answer a similar purpose, joined to the circumstance of  their not
being found in every class, induced me to conclude that this opinion
was erroneous.   To throw  as much light upon this subject as
possible I made a number of experiments, and availed myself of every
opportunity which offered of examining whatever could in any way
elucidate the point; and, from  what I have been able to  collect, I
think it will appear that they cannot be considered as reservoirs of
the semen.
  To proceed regularly with  my investigation, I shall begin by
comparing  the  contents of  these vesiculae with  the semen as it is
emitted from the penis of a  living  man.  From which comparison
it will appear that the  two  secretions are very different in their
sensible properties of colour and  smell;  and although the semen
which constitutes the first part of the emission  is evidently different
from the last, yet every part of it is unlike the mucus found in these
vesiculae.
  The  semen first discharged from the living  body is of a bluish
white colour, in consistence like cream, and similar to what is found
in the vasa  deferentia after death ; while that which follows is some-
what like the common  mucus of  the nose, but less viscid.   The
semen becomes  more fluid  upon exposure  to  the air, particularly
that first thrown out;  which is the  very reverse of what happens
to secretions in general.  The  smell of the semen is mawkish  and
unpleasant,  exactly resembling that of the farina of the Spanish chest-
nut ; and to the taste, though at first insipid, it has so much pungency
as, after some little time, to  stimulate and excite a decree of heat
in the mouth.  But the  fluid  contained in these vesiculle in a dead
body is of  a brownish  colour, and often varies in  consistence in
different parts of the bag, as if  not well mixed.  Its  smell does not
resemble that of the semen, neither does it become  more fluid by
being exposed to the air. 
GLANDS CALLED VESICULAE  SEMINALES.          59
  It may, however, be answered to  this that  the  contents of the
vesiculae are generally found in a putrid  state, and  have by that
means undergone a change  in  their sensible properties.  But the
objection is readily obviated  by  comparing this fluid with that in the
vasa deferentia  as it comes from the  testicles of  the  same dead
body, between which there appears to be no resemblance.
  To be still more certain of the nature of what these vesiculae con-
tain than was possible from  the examination of bodies  which had
been dead some  time, I took an opportunity of opening a man, im-
mediately after his  death, who  had  been killed by a cannon-ball.
The fluid in the  vesiculae was of a lighter colour than has usually
been found in men who have been dead a  considerable time;  but
it was not by any means like the semen either in  colour or  smell.
In another man  who died instantaneously, in consequence of falling
from a considerable height, whose body I inspected soon after the
accident, the contents  of the vesiculae  were of  a lightish  whey
colour, having nothing of the smell of semen, and in so fluid a state
as to run out on cutting into them.
  I have likewise examined with attention a mucus which some
men discharge upon straining hard while at stool, or after throwing
out the last drops of urine, an action which requires a considerable
exertion of the parts.   This  discharge is generally called a seminal
weakness, and is I believe commonly supposed to  be the semen ;*
but in  all cases of this kind in which I have been consulted it nearly
resembled the contents of the vesiculae  in  the dead  body, though
perhaps not quite of so deep a  colour.   I  endeavoured  in vain to
persuade a gentleman who had  this complaint that the discharge
was not seminal, till by examining his own semen  and comparing
it  with that mucus he  was convinced of the difference.  This
gentleman had the power of emitting the semen in the same  quan-
tity as usual immediately after  the mucus had  been discharged,
which is a further proof that this fluid is not semen.f
  In this country eunuchs seldom come under our  examination;
but we have sometimes opportunities of opening the bodies of those
who have, in consequence of disease or accident, lost one or both
testicles; and several subjects of this kind  I have inspected after
death.  Persons who have had  one testicle taken  away will better
illustrate the point in dispute than those who have been deprived of
both.  For it is  to be presumed that such men have afterwards had
connexion with  women,  and consequently had the action of emis-
sion, which must have  emptied  the vesicula of the castrated side, if
this had  contained semen; and, as it could not  be replenished, it
should have been found empty  after death.   We have also in such
cases  an opportunity of making comparative observations between

  * Vide  Treatise  on the Venereal Disease, edit. 1st and 2d, p. 197. [vol. ii.,
p. 167 of the present edition.]
  + The discharge was truly supposed to be the contents of the vesicula*; and,
it being imagined  that these  contained  semen, according to this  reasoning the
discharge must be seminal. 
60
HUNTER ON THE ANIMAL (ECONOMY.
the vesicula of the perfect and that of the imperfect  side.  In |n
eunuch such emissions never can  happen, for the testicles being
gone the natural and leading stimulus is lost; therefore, if in them
the vesiculae were found full after death, it might be supposed to oe
the semen which they had received from the testicles before casV"a"
tion that had remained there from  the time of the operation;  but
castration being, in such cases, usually performed on children, this
circumstance  should  rather be  considered  as  a proof that tney
secrete their own mucus.  Yet it is probable the vesiculae will  nei-
ther be so large nor so full in eunuchs as  in the  perfect ma";,   r.J.
am of opinion  that they are connected with generation, and that it
the constitution is deprived of that power  these bags will not grow
to the full size.  But*  where only  one testicle is removed its loss
does not in the least affect generation, therefore  does  not  produce
any change in the  vesicula of that  side from which the testicle is
taken; because the vesicula does not depend upon the testicle for
its secretion, but upon the constitution,  and on  the  person being
capable of the act  of generation : therefore as one testicle  is suffi-
cient  to preserve manhood,  it is of  course  capable of keeping up
the action of both  those glands.
   A man who had been under  my care, in St.  George's Hospital,
for a venereal complaint, died there, and was discovered  to have
lost his right testicle.   From the cicatrix being hardly observable
it must have been removed some considerable time before his death;
and the  complaint for which he  was received into the hospital is a
convincing proof that  he  had connexion with  women after  that
period.
   I inspected  the body in the presence of Mr. Hodges, the house-
surgeon, and several of the pupils  of the hospital.  Upon dissecting
 out and  examining the contents of the pelvis, with the penis  and
 scrotum, I found that the  vas deferens of the right side was smaller
 and firmer in  its texture than the other, especially at  that end next
 to the abdominal rings, near to the part which had been cut through
 in the operation.  The cellular membrane surrounding the duct, on
 the right side, was not so loose as on the  left; neither were the
 vessels which ramified on the right  vesicula so  full of blood.   But
 upon opening the  vesiculae,  both appeared to be  filled with the same
 kind of mucus, and similar to that which  is found  in  other  dead
 bodies; the vesicula of the right side being rather larger than that
 on the left.   Whatever, therefore,  may be the real use of  these
 vesiculae, we  have a proof from this dissection  that in the human
 subject they do not contain the  semen.
    In a  man who  died in St. George's  Hospital with a very large
 bubonocele, the testicle of the diseased side was discovered to have
  almost  lost its natural texture, from  the pressure of the hernial sac ;
  and upon examining the testicle  with attention there was no appear-
  ance of vas  deferens till we came  near the bladder, where it was
  almost  as large as usual.  The  vesicula  of that side was found to
  be as full as the other, and to contain the same kind  of mucus. 
            GLANDS CALLED VESICULAE SEMINALES.         61

  I extirpated the left testicle of a Frenchman, who was a married
man, and died about a year afterwards, having been extremely il.
for several months before hia death.  On examining the body, the
vesiculae were both found nearly full, more especially that on the
left  side, which might be  accidental;  but the vas deferens of the
left  side, where it lies along this bag,  and where it has a similar
structure with the'vesiculae,'was  likewise filled with the same kind
of mucus;  which I  believe is always the case, whether the testicle
has  been removed or not.
   A young man, a  coachman, with his  left testicle much diseased,
had it  removed, at St.  George's Hospital,  by  Mr. Walker,  in
August 1785; and in February 1786 he returned again to the hos-
pital, on account of uncommon pains  all over him.  For  these he
requested to be put  into  the warm bath;  but  as  he was going
from the ward for that purpose, he dropped  down almost imme-
diately.  The body was inspected,  with a view to  discover the
cause of his death ; and, upon examination of the vesiculae, the bag
of the left side was as  full as that on  the right, and the contents in
both were  exactly  similar.   In the winter 1788  another case oc-
curred nearly resembling the above.
   In dissecting a male subject, in the year 1755, for a side view of
the  contents of  the pelvis, I found a bag on the left side, lying con-
tiguous to the peritonaeum, just on the  side of the pelvis where the
internal iliac  vessels  divide above  the angle of reflection of the
peritonaeum at the union of the  bladder and rectum.  The left vas
deferens was  seen passing on to this bag; and what is very singular,
that of the right, or  opposite side, crossed  the bladder, near its
 union with the rectum, to join it.  I traced  the left vas deferens
down to the  testicle;  but, on following the right through the ring
" of the external  oblique muscle, I discovered that it terminated at
 once, about an inch from its passage out of the abdomen, in a blunt
 point, which  was impervious.   On examining the spermatic chord
 from this  point to the testicle,  I could not find any vas deferens ;
 but, by  beginning at  the testicle, and tracing the epididymis from
 its origin,  about half-way along where it lies  upon the body of the
 testicle, I perceived that it at first became straight, and soon after
 seemed to terminate  in a point.  The canal at this part was so
 large as to allow of being filled  with  quicksilver; which, however,
 did not  pass far, so that  a portion of  the  epididymis was wanting,
 and likewise the vas deferens  for  nearly the whole length of the
 spermatic chord of the right side.  On  the left side the vas deferens
 began where the epididymis commonly terminates, and there was
 a deficiency of nearly an inch of the extremity  of the epididymis.
 I then dissected the bag above  mentioned, which proved to be the
 two vesiculae;  for, by blowing air from one  vas deferens, I could
 only inflate half of it, and  from the other vas deferens the other
 half.  They contained the  mucus commonly found in these bags ;
 but, upon  the most  accurate examination,  I could neither discover
                                7 
62
HUNTER ON THE ANIMAL CECONOMY.
any duct leading  from them to the prostate gland, nor the remains
of one.                                                     .  t-  n
   It was evident in this subject that there was no communication
between the vas deferens and epididymis, nor between these bag
and the urethra.  The caput  gallinaginis had the common appear-
ance, but there were no orifices to be found.   The  testicles  were
very sound,  and the ducts  from them to the epididymis were very
manifest and contained semen.*                                 ,
   From these circumstances we have a presumptive proof that the
semen can be absorbed in the body of the testicle and in the epididy-
mis, and that the  vesiculae secrete a mucus which they are capable
of absorbing when it cannot be made  use of.  We may likewise
infer from what has been said that the semen is not retained in re-
servoirs after it is secreted, and kept there till it  is used, but that it
is  secreted at the time in consequence of certain affections of the
mind stimulating  the  testicles to this  action; for we find  that  if
lascivious ideas are excited in the mind, and the paroxysrn is after-
wards prevented from coming on, the testicles become painful and
swelled from, we may suppose,  the quantity of semen secreted, and
the increased action of the vessels, which pain and  swelling is re-
moved immediately upon the paroxysm being brought on and the
semen evacuated; but if that does not take place, the  action  of the
vessels will still be kept up, and the pain in the testicle in general
continue till  the paroxysm  and evacuation  of the semen is brought
on to render the act complete, without which a stop cannot  be so
quickly put to the action of the  vessels that produce the secretion,
nor the parts be allowed so  easily to resume their natural  state.
There is at this time no sensation of any kind felt in the seat of the
vesiculae seminales, which  shows that the action is in the testicles,

  * As the semen, in consequence of this preternatural formation of parts, could
not be conveyed to the  urethra in the  usual way, I  conceived  it possible that
there might be another  unnatural construction to make up for the deficiency in
the vas deferens, and therefore examined it very carefully to see if there were no
supernumerary vasa deferentia.   I was led to do this more particularly from often
finding parts resembling them where they could answer no kind  of purpose.  By
a supernumerary vas deferens I mean a small duct which  sometimes arises from
the epididymis, and passes up the spermatic chord along with the  vas deferens,
commonly terminating in a blind end, near to which it is sometimes a little en-
larged.  I never found this duct goon to the urethra; but, in  some instances,
have seen it accompany the vas deferens as far as the brim of the pelvis.  There
is no absolute  proof that this is a supernumerary vas deferens; but as  we find
the ducts of glands in general very subject to singularities, and that there are fre-
quently supernumerary ducts; that there are  often two  ureters to one  kidney,
sometimes distinct from beginning to  end ;  at other times both arising from one
pelvis.  These ducts, arising from the epididymis, I am inclined from  analoo-y
to believe are of a nature similar to the double ureters.  They resemble the va3
deferens, as being continuations of some of the tubes of the epididymis; are
convoluted where they come off from it; afterwards become a  straight canal' and
passing along with it for some way, they are then most commonly "obliterated.
   The idea of their being for the purpose of returning the superfluous semen' to
the circulation must certainly be erroneous, from their being so seldom met with
and so very seldom continued further than the brim of the "pelvis. 
            GLANDS CALLED VESICULAE SEMINALES.         63

and in them alone.  The pain in the testicles, in  consequence  of
being filled with semen and of the action being incomplete, is some-
times so considerable as to make it necessary to produce an evacua-
tion of the semen to relieve the patient.
  It may be observed, in support of this opinion, that these bags
are as full of mucus in bodies much  emaciated, where the person
has died from a lingering disease, as in those of the strong and
robust, whose death has been occasioned by violence or acute dis-
eases ; and they are nearly as full in the old as in the young; which,
most probably, would not be  the case if they contained semen.
These facts, taken from  the human subject, are, I think, sufficient to
establish the opinion which I have laid down;  but, for the satisfac-
tion of others, I shall give such facts and observations as have  oc-
curred in my  dissection of different animals  as tend to clear up the
point in question.
  These vesiculae are not similar either in shape or contents in any
two genera* of animals which  I have dissected; and  they differ
more in size, according to the bulk of the animal, than  any other
parts whose uses in different animals are supposed to correspond ;
while the semen in  most of those which I have examined may be
said to be similar.
  The resemblance which obtains between these bags and the gall-
bladder in the human subject by no means holds equally good when
applied to other animals.  In the horse they  are like twof small
urinary bladders, almost loose and pendulous, with a partial coat
from the peritonaeum, under which there are two layers of muscular
fibres; they are thicker in their coats at the fundus than any other
part, and appear there  to  be glandular.  Their  openings into the
urethra are very large,  and although they open close to the vasa
deferentia do  not communicate with them.  The  septum between
the two ducts is not continued on quite to the  urethra, so that they
Cannot, in strict language, be said to enter that passage separately;
but there is not length of common duct sufficient to admit of regur-
gitation from  the vasa deferentia into these bags.  They are not of
the same size in the gelding and in the stone-horse, being large  in
the last.  Their contents in both  are exactly similar, and nearly
equal in quantity;  but in no way resembling the semen emitted by
the stone-horse in the coitus, or what is found in  the vas deferens
after death.
   In  the boar  these  bags  are  extremely large, and divided  into

  * [This term  is here used in a more extended sense than in the present systems
 of natural history; but even  as applied to the Linnaean genera the rule is affected
by numerous exceptions of which a comparison of the vesiculae seminales of the
 ape with those of the human subject affords a striking example.]
  f [There is also in the horse a third vesicula seminalis, of a similar structure to
the two lateral ones, between which it is situated, and having, like them, no com-
munication with the  vasa deferentia.  This want of  correspondence therefore
between the number of the vesiculae and that of the testes affords another argu-
ment against their having the relations to  each other which exist between the
 gall-bladder and liver.] 
64
HUNTER ON THE ANIMAL CECONOMY.
cells of a  considerable size; or they may more properly be  said
to  form ramifications  closely  connected with  one  another,  and
having a large canal or duct  common  to the whole.  The ducts
contain a  whitish fluid, very unlike  what  is  found in  the vasa
deferentia  of the same animal, with which they  have not  the least
communication.*
  In the rat the  bags are  large and flat,  with serrated edges, and
lie some way within  the abdomen, containing a  thick ash-coloured
mucus, nearly of the  consistence of soft cheese;  very different from
what is found in the vasa deferentia of the same animal, with which
they do not communicate.
  In the beaver the bags are convoluted ;  their ducts have no com-
munication with the vasa deferentia, but both the one and the other
open on the verumontanum.
  In the Guinea-pig  they are  composed of long cylindrical tubes,
and lie in  the cavity of the belly, are smooth on  their external
surface, and do  not communicate  with the vasa deferentia.   They
contain a thick, bluish, transparent substance, which is softest near
the  fundus, and becomes firmer towards the openings into the urethra,
where it is as solid as common cheese.   From  this circumstance,
and what is observed in  the horse, the fundus  appears  to  be the
part that secretes this substance, which is very different in  colour
and consistence from the  contents of  the vasa deferentia, and is
often found in broken pieces in the urethra.
  To be more certain that the  substance contained in these bags
was not the secretion of the testicle, I extracted  one of the testicles
of a Guinea-pig; and six months afterwards gave it the female.   As
soon as the action of copulation was over (in which all  the parts
containing semen  should  naturally have emptied  themselves)  I
killed the animal, and upon examination  found  the vesicula of the
perfect side, and that of the side from which the testicle  had been
removed, both filled with a substance in every respect similar.  It
will scarcely be alleged that  this substance had been contained in
the bag before the extirpation of the testicle ;  nor could it  be semen,
which must have been  all  thrown  out in the previous connexion
with the female.
  To ascertain  that the contents of the vesiculae are not discharged
into the vagina of the female with the semen in the act of emission,
I killed  a female  Guinea-pig  as  soon as  the  male had left  her,

  * [Tyson particularly notices the glandular structure of  the vesiculae seminales
in the peccari and boar, and was led  by this circumstance to  the same opinion
respecting their nature and use as Mr. Hunter is endeavouring to establish by a
more extensive and various induction in the present paper.  "John van Horn "
says Tyson,  " would have a threefold matter of the seed :  one from the testes, the
second from  the vesiculae seminales, and a third from the prostates.  But this De
Graaf strongly opposes; and will admit only that from the testes, which is trans-
mitted to the vesicula? seminales, but not at all bred  there.  But in our subject, and
so in some others, they being glandulous, they must therefore secrete some juice ;
which, in all likelihood, is some way serviceable, though not principally, in o-ener-
ation."—inatomyofthe Mexico Musk-hog, Phil. Trans., vol. xiii. p. 370, 1683.] 
GLANDS CALLED VESICULAE SEMINALES.          65
and  examined with attention what was contained in  the  vagina
and uterus;  in  neither could I  find any of the mucus of the vesi-
culae, which from its firmness must have been easily detected.
  In  the hedgehog  these bags are very large, being more than
twice the size of the vesiculae in the human subject.
  Many animals have no such bags; and I believe they are want-
ing in the greater part of that class which live chiefly upon animal
food ;  they are, however, to be found in some of them, and the
hedgehog is an example.*  There is no apparent difference in the
testicles, vasa deferentia, or semen of the animals which have
vesiculae and of those which have none; and the mode of  copula-
tion, as far as these bags can be concerned, is very similar in both.
  In birds, as far as  I have yet observed, there is nothing analo-
gous to these bags ; and yet there appears to be no difference between
the mode of copulation  of  the  drake and the  bull or ram.  It is
very  natural  to suppose that if the  vesiculae  were reservoirs  of
semen they would be more  necessary in birds,-who have the power
of repeating the  act of  copulation in an  infinitely greater degree
than quadrupeds; and indeed we find that in birds there are reser-
voirs, which  may account for this power; the vasa deferentia being
enlarged just before they open into the rectum, probably to  answer
that intention.  As birds have no urethra, some having merely a
groove,  as the drake and gander, f and many being even without a
groove,  as the common fowl,  it was  absolutely  necessary there
should be such  a reservoir  somewhere; and the necessity of this
will appear more evidently  by and by.
  What I have observed of the reservoir of birds is equally appli-
cable to amphibious animals, and to that order of fish called rays.
   From the  above observations I think we may fairly conclude that
these  vesiculae  are not  for  the purpose of containing  semen: the
single circumstance of their ducts being united to those of the tes-
ticles in the human subject  not  appearing sufficient to set aside the
many facts which are contradictory to such an opinion.
  Having endeavoured  to show that the function of these vesiculae
has  hitherto been misunderstood, the  following observations will
tend to prove that they are subservient to generation, though their
particular use is not yet discovered ; and, for the better understand-
ing this part of the subject, I shall premise the following facts.
   Animals have their natural feelings  raised or increased accord-
ing to the perfection of the parts connected with such feelings ; and
the disposition for action is  also in proportion to the state of the

  * [The vesiculae seminales are wanting in all the Ferae with the exception of
the Insectivora ; also in the Ruminants, in the carnivorous Cetacea, and in  all
the Marsupiata; they are equally wanting in the insectivorous Monotremata,
whicli of all mammiferous animals approximate most closely to the oviparous
Vertebrata.]
  | [After repeated examination, we find the structure of the urethra in the drake
to be as here described, viz., a groove, and not a complete canal, as represented
by Sir Everard Home.  See Phil. Trans. 1802, p. 361,  pi. xii.]
                                7* 
66
HUNTER ON THE ANIMAL (ECONOMY.
parts and the excitement of such feelings.  But, that these feelings
may be duly excited, it is necessary that the animal and the parts
should be healthy, in good  condition, and  in a certain  degree ot
warmth suitable to that class to  which the animal belongs.  In the
greatest part of the globe there is  a difference in the warmth ot
the same district at different periods, constituting the seasons ; and
the cold in some of them is so  considerable as to prevent those
feelings or dispositions in animals from taking place, and  to render
them, for the time, unfit for  the  purposes of generation.'   This is
owing to the testicles becoming at this season small, and being there-
fore unfit  to give such dispositions, as is the case  in very young
animals.   This fact is very obvious in birds, of which the sparrow
may be produced as a proof.   For if a  cock-sparrow is killed in
the winter, before the  days have begun to lengthen,  the testicle will
be found very small; but if that organ is examined at different times
in other sparrows, as the warmth of the  weather increases, and if
this examination is continued to  the breeding-season, the difference
in the size of the testicle will be very striking.  This circumstance
is not peculiar  to birds, but is common, as far as  I  yet know, to
all animals which have their seasons of  copulation.  In the buck
we find the testicles are reduced  to a very small size in the winter;
and  in  the  land-mouse, mole, &c, this  diminution is still  more
remarkable.  Animals, on  the contrary, which are not in a state
of nature have no such change taking place in their testicles;  and,
not being much affected by seasons, are consequently always in
good condition, or in a state to which other animals that  are left to
themselves can  only attain  in the  warmer season.  Therefore in
man, who is in the state we have last described, the  testicles are
nearly of the same size in winter as in summer ; and nearly, though
not exactly, the same thing may  be observed in the horse, ram, &c,
these animals having their seasons in a certain degree.
  The variation above taken notice of is not confined to the testicles,
but also extends to the parts which are connected with them. For
in those animals that have their  seasons  for propagation the  most
distinctly marked, as the land-mouse, mole, &c, the vesiculae are
hardly discernible in the winter, but in  the spring  are very  large,
varying in size in a manner similar to the testicle.  It may, however,
be alleged that the change in these bags might naturally be supposed
to take place, even admitting them to be seminal  reservoirs; but
what happens to the prostate gland, which has never been supposed
to contain semen, will take off the force  of this objection, since in
all the animals which have such a gland (and  which have  their
season for propagation) it undergoes a similar change.  In the mole
the prostate gland in winter is hardly discernible, but in the spring
becomes very large and is filled with mucus.

   * It is not  required  that the season for the  copulation of different animals
should be equally warm ;  for the frog copulates  in very cold  weather, while the
snake and lizard, which are also cold, sleeping animals, do not copulate till the
season is warm. 
GLANDS CALLED VESICULiE SEMINALES.          67
   From  these observations it is reasonable to infer  that the use of
 the vesiculae in the animal oeconomy must, in common  with many
 other parts, be dependent upon the testicles.  For the penis, urethra,
 and all the parts connected with them, are so far subservient to the
 testicles that I am persuaded few  of them  would  have  existed if
 there had been no testicles in the original construction of the body ;*
 and these would have been so formed as merely to assist in the ex-
 pulsion of the urine.   To illustrate this opinion, let us observe what
 is the difference between these parts in the  perfect male  and  in  a
 male that has been deprived of the testicles when  very young, at
 an age in which  they have had no such  influence upon the animal
 ceconomy as to  affect the growth of the other parts.   In'the perfect
 male the penis is large;  the corpora cavernosaf being capable of
 dilatation.   The corpus  spongiosum is very vascular ;J that part of
 the canal which  is called the bulb is  considerably enlarged, form-
 ing  a cavity;  and  the  musculi-accelerators  urinae,  as they are
 termed, are strong and healthy.  In  many animals  which have a
 long  penis, the muscular  fibres are  continued  forwards to the end
 of it;  and  in others,  though not extended so  far, they are  very
 large.
   On the contrary, in the  castrated  animal the penis is small, and
 not capable of much  dilatation ; the corpus spongiosum is less vas-
 cular;  the cavity at  the bulb is a  little larger than the canal of the
 urethra;  and the muscles are white, small, and have a ligamentous

   * [The construction and functions.of the penis in reptiles and those birds which
 possess the organ prove the correctness of this view; and very striking evidence
 of the exclusive relation of the penis to the functions of the testes  is afforded by
 the discoveries in natural history which have been made since the time of Hunter.
 Thus, in those  remarkable  Australian quadrupeds, the Ornithorhynchus and
 Echidna, which form the passage from the mammiferous to the oviparous verte-
 brates, the penis, although perforated through  its whole extent, does not  carry
 off the urine, which  escapes by the cloaca, but the urethra is destined solely for
 tne passage of the fecundating fluid during the time of the coitus.]
  f The cells of the corpora cavernosa are muscular, although no such appearance
 is to be observed in  men  ; for the penis in erection is  not at  all  times equally
 distended.   The penis in a cold day is not so  large in erection as in a warm one;
 which, probably, arises from a kind of spasm that could not act  upon it if it were
 not muscular.
  In the horse the parts composing the  cells  of  the penis appear evidently
 muscular to the eye; and in a horse just killed they contract upon being stimu-
 lated.a-
  X It may not be improper to observe, that the  corpus spongiosum urethrae and
 glans penis are not spongy or  cellular, but  made up of a plexus of veins.   This
 structure is discernible in the human subject, but much more distinctly seen in
many animals, as the horse, &c.
  a [The disposition of the muscular fasciculi of this part is chiefly longitudinal,
interlacing in an undulating manner with the transverse tendinous fibres.  They
are mo3t numerous near the termination of the corpora cavernosa, and gradually
diminish as they approach the origin.  When examined with a high magnifying
power the  ultimate fibres of these fasciculi exhibit, but in a fainter degree, the
transverse striae characteristic of the voluntary muscular fibre.] 
68
HUNTER ON THE ANIMAL CECONOMY.
appearance.   The  same  observations are  true, if  applied  to the
erectores penis.
   The penis of the perfect male is of a  sufficient length, when
erected, to reach to the further end of the vagina of  the female.  In
the castrated animal it is  much shorter, and erections having then
become unnecessary, the  parts which should  project often  adhere
to the inside of the prepuce.   The erectores  muscles in the  perfect
male are  strong  enough to squeeze  at once  the blood  out of the
crura into the body of the penis, so as to straighten and contract
the  urethra  instantaneously,  and  the acceleratores  urinae*  have
sufficient power to throw out the semen  that is gradually accumu-
lated at the bulb for ejection.
   The prostate gland,f Cowper's glands, and the glands along the
urethra (of which the  lacunae are the excretory ducts), are in the
perfect male  large and pulpy, secreting  a considerable quantity of
slimy mucus, which is salt to the taste;  it is most probably for the
purpose of lubricating those parts, and is only thrown  out when in
vigour for copulation :  while in the castrated animal  these are small,
flabby, tough, and ligamentous,  and have  little secretion.   From
this account  there  appears to be  an essential  difference between
the parts connected with  generation of the perfect male, and those
which remain in one that has been castrated, more especially if that
operation had been performed while the  animal was young.
   If it is objected that the same  changes did not take  place in the
men from whom one testicle had been removed, it may be answered,
that  the  operation was  performed late in life: and one  testicle
being left, that was sufficient to carry  on  the  necessary  actions,
and consequently to preserve  the powers; therefore whatever parts

  * I shall call these muscles 'expulsores seminis,' as  I apprehend their real
use to be for the expulsion of that secretion : these muscles, likewise, throw out
those drops of urine which are collected in the bulb  from the  last contractions of
the bladder, and they have been, from this circumstance, named  acceleratores
urinae; but if a receptacle had not been necessary for the semen, those muscles
had probably never existed, and the last drops of urine would have been thrown
out by the action of the bladder and urethra, as  in  some measure is the case in
the castrated animal.  That the urethra has the power of contraction is evident
upon the application of any stimulus, for I have seen the urethra refuse to allow
an  injection to pass on;  and  in that part where the injection  stopped, a fulness
was felt, which terminated at once: this contraction is most probably in  the
internal membrane;  it also will often refuse the passage of a bougie.
  | The prostate gland is not common  to all animals.  It is wanting in the bull,
buck, and most probably, I believe, in  all ruminating animals.  In  this class the
coats of the vesicular are much thicker and more glandular, than in those which
have prostate glands; it is therefore natural to suppose that the vesiculae  answer
nearly the same purposes as the prostate gland.a
   The prostate gland, and Cowper's glands, as well as the vesicula?, are wanting
in birds, in the amphibious animals, and in those fish which have testicles, as all
of the ray kind.
  a [The  glands in Ruminants here termed ' vesicular,' are now regarded
bifid prostate.] 
GLANDS CALLED VESICULA SEMINALES.
69
had a  connexion with these powers, would still have'the stimulus of
perfection given to them.
   The different appearance, of the bulb and the muscles would seem
to point out, in the perfect male, the enlargement of the bulb to be
for the purpose of a receptacle for the semen ; for although I have
denied the vesiculae to be reservoirs, yet, as it was necessary that
the semen should be accumulated somewhere before ejection, I shall
endeavour to prove, from the mode of copulation  in the animals  we
are best acquainted with,  that the bulb is intended for that purpose.
Let us, therefore, give a short account of the different parts con-
cerned in coition ; and by observing the dependence which they have
upon one another, see how this proof will come  out.
   The erection of the penis is produced by a stop being put to  the
returning blood, and this stoppage is so complete, that no mechani-
cal  pressure  applied to the body of the penis  can force the blood
on into the veins.  This  erection answers  two  purposes; it gives
size and strength to the penis, and it renders the canal of the urethra
smaller.   The  corpus spongiosum of the urethra  and the glans,
which is only a continuation of it, are filled with  blood from  the
same cause, but not so completely as the body of the penis, since from
them it can be forced out into the veins by pressure.*   This accu-
mulation of blood in the corpus spongiosum diminishes the canal of
the urethra so much, that  any pressure upon one part of it will  have
a considerable effect upon the other; not only by lessening its capa-
city at the part pressed, but by forcing the blood forward, the parts
beyond will be still more  distended, and  consequently the canal of

   * In April 1760, in the presence of Mr. Blount, I laid bare the penis of a dog,
almost through  its whole length ; traced the two veins that came from the glans
(which in this  animal makes the largest part of the penis), and separated them
from the arteries by dissection, that I might be able to compress them at pleasure
without affecting the arteries.  I then compressed the two veins, and found that
the glans and large  bulb became full and extended ; but when I irritated the
veins,  in order  to see if there  was any power  of contraction in them which
might occasiohally stop the  return of the blood, no such appearance could be
observed.a
  a [From this experiment, it is obvious that Hunter regarded the stoppage of
the circulation  through the veins as  being produced  by external compression.
Douglas (Myographies  Comparatse Specimen, p. 9), had previously described the
muscles which  compress the  vena dorsalis penis in  the dog; and Cowper had
more fully and particularly detailed the structure and actions of the muscles
which have a corresponding office in the opossum, observing that "the muscles
of the cavernous bodies of the penis of this creature, having no connexion with the
os pubis, cannot, apply the dorsum penis to the last-named bone, and compress
the vein of the penis, whereby to retard the refluent blood and cause an erection,
as we have observed in other  creatures; but  some large veins of the penis here
take a different course, and pass  through the middle parts of the bulb, and  are
only liable to compression made by the intumescence of the muscles C C (mus-
cles of the bulb) that  inclose them.  "But the chief agent in continuing  the
erection of the penis in this animal is the sphincter muscle of its anus, or rather
cloaca;  and not only the sphincter muscle of the cloaca of the male opossum,
but that of the female  also closely embraces the penis in coition, and effectually
retard the refluent blood from  its corpora cavernosa, by compressing the veins of
the penis." (Phil. Trans., vol. xxiv.  1704, p. 1581.)] 
70            HUNTER ON THE ANIMAL CECONOMY.

the urethra  be in that proportion diminished.  The semen, in the
time of copulation, in such  animals as remain long  in  that ac '
gradually squeezed along the vasa deferentia (as it is secretea; in
the bulb; and when  the testicles cease to secrete, the  paroxysm,
which is to finish the whole operation, comes on.  The semen acting
as a stimulus to the cavity of the bulb of the urethra, the muscles
of that part of the canal are thrown into action; the fibres neaiest
the bladder, probably, act first, and  those  more forward in quick
succession : the semen is projected with some force; the  blood  in
the bulb of the urethra is by the same action squeezed forward, but
requiring a  greater impulse to propel it, is  rather later than the
semen, on which  it presses from  behind; the corpus  spongiosum
bem* full of blood, acts almost as quick as undulation, in which it
is assisted by the corresponding constriction of the urethra, and the
semen is hurried along with a considerable velocity.*
   From  the  facts which I  have  stated  respecting the  organs ot
generation, the observations which  I have made, and the series of
actions which  I have considered  as taking place in the copulation
of animals, I think the following inferences may be fairly drawn.
   That the bags, called vesiculae seminales, are not seminal reser-
voirs, but glands secreting a peculiar  mucus ; and that the bulb of
the urethra is, properly speaking, the receptacle in which the semen
is accumulated previous to ejection.
   Although it seems to have been proved that  the vesiculae do not
contain the semen, I have not been able to ascertain their particular
use ;  we may, however, be allowed upon the whole to conclude that
they  are, together with  other  parts, subservient to the purposes of
generation.
          3.  ACCOUNT  OF THE FREE-MARTIN.

  Generation-, from a seed, requires the concurrence of two causes
to give it perfection: the one  to form  the seed, the other  to give it
the principle of action.f

  * [Besides the functions here assigned to the bulb of the urethra, in relation to
the reception and propulsion of the semen, we may also notice its uses  in reference
to the distention of the glans penis, of which Cowper, in his description of the
male organs of the opossum  above quoted, gives a remarkable example.  He
observes : " As the bulb of the urethra in man is framed for the use of the glans,
to keep it sufficiently distended when required, so it seems it is necessary to have
two of these bulbs inclosed with their particular muscles in this animal, to main-
tain  the  turgescence of its double  or forked glans  when  the penis is erected."
(Phil Trans., vol. xxiv., 1704, p. 1585.)]
  f It may be  necessary for some of my readers to have explained to them what
I mean by a seed.  I do suppose that the word seed was first applied to grain, or 
OF THE  PREE-MARTIN.
71
   The cause  forming  the seed is  called the female, the other the
 male ;  but those two causes in general make only a part of a whole
 animal, or are rather parts superadded to an  animal.  Probably
 these characteristics were first observed in such animals as had the
 female parts complete in one, and the male in the other ; therefore
 the terms female and male have been applied to the whole animal,
 dividing them into two distinct sexes, and  the parts which formed
 the one sex or the other were called the female 01 the male parts of
 generation.  But, upon a  more accurate knowledge of animals and
 of their parts of generation, these were found in many of the inferior
 tribes to be united  in the  same animal, which from possessing both
 has got the name of hermaphrodite.
   As  the distinction of male or female  parts is natural to  most
 animals, as the union of them in the same animal is also natural to
 many, and as  the separation of them is only a circumstance making
 no essential difference in the structure of the parts'themselves,  it be-
 comes  no great effort or  uncommon play in Nature  sometimes to
 unite them in those animals in which they are commonly separated ;
 a circumstance we really  find takes place in many animals of those
 orders in which such an union is unnatural.   From this state of the
 case hermaphrodites may be divided into two kinds, the natural and
 unnatural.
   The natural hermaphrodite belongs  to  the inferior and  more
 simple genera of animals  of which there is a much greater number
 than of the more perfect;  and as animals become more complicated,
 have more parts, and each part is  more confined to its particular
 use, a separation of the two necessary powers for" generation seems
 also to take place.*

 that which is always called seed in the vegetable; which seed is the part of such
 vegetables in which the matter  of the young vegetable exists or is formed.  The
 principle of arrangement in the farina, or  male part, fitting the seed for action,
 being at first not known, a false analogy between the vegetable and animal was
 established, and the matter secreted by the testes was called the seed ; but, from
 the knowledge of the distinct sexes in the vegetable, it is well known that the
 seed is the female production in them, and that the principle of arrangement for
 action is from the male.  The same operation and principles take place in many
 orders of animals, the female producing a seed in which is the matter fitted for
 the first arrangement of the organs of the animal, and  which receives the principle
 of arrangement fitting them for action from the male.
  *" [The animals in which the organs of the two sexes are naturally combined
 in the same individual are confined to the  invertebrate division,  and are  most
 common in the molluscous and radiate classes.  If the term hermaphrodite may
 be applied to those species which propagate without the concourse of the sexes,
 but in which no distinct male organ can be detected, as well as to those in which
 both male and female  organs  are present  in the same body, then  there may be
 distinguished three kind* of hermaphroditism.
  First, the cryptandrous, or in which the female or productive organs are  alone
developed.  Ex.  the  accephalous  mollusks, as the oyster, lamp-cockle, and
ascidia;  the cystic entozoa, echinoderms, acalephes, polyps, and sponges.
  Second, the heautandrous, or in which the  male organs are developed, but so
disposed as to fecundate the ova of the same individual.  Ex. the  cirripeds, the
rotifers, the tremaiode and cestoid entozoa,
  Third, the allotriandrous, or in which the male organs are so disposed as not to 
72             HUNTER ON THE  ANIMAL CECONOMY.
   The unnatural hermaphrodite,* I believe, now and then occurs in
every tribe of animals having distinct sexes, but is more  in common
in some than in others ;f and is to be met with, in all its  gradations,

fecundate the ova of the same body, but where the concourse of two individuals is
required, notwithstanding the co-existence in each of the organs of the two sexes.
Ex. the gastropodous mollusks, with the exception of the pectinibranchiate order,
the class Annellida.
  All the other invertebrates, as the cephalopods  and pectinibranchiate gastro-
pods, the insects, arachnidans  and  crustaceans, the  epizoa, and  the  nematoid
entozoa, are, like the vertebrate classes, dioecious,  or composed ot male and.
female individuals.]                                            .
  * [The unnatural hermaphrodites  may be divided into those in which the  parts
peculiar to the two sexes are blended together  in different proportions, and the
whole body participates of a neutral character, tendingtowards the male and female
as the respective organs predominate, and into those in which  the male and
female organs occupy respectively separative halves of the body, and impress on
each lateral moiety the characteristics of the sex.  This latter and very singular
kind of hermaphroditism has hitherto been found only in insects  and crustaceans.
In the Extracts from the Minute-Book of the Linnean Society, printed in the 14th
Vol. of their Transactions, it  is stated that Alex. MacLeay, Esq., Sec.  L.S.,
exhibited a curious  specimen showing that two Papiliones, referred to distinct
families by Fabricius, are in reality the  male and female of the  same species.
This specimen presented the forms and colours of both sexes, divided by a longi-
tudinal line on the body: the right wings and side of the body being as in the
male (Papilio Polycaon, Fabr.), and the left as in the female (Papilio Laodocus,
Fabr.).  In Loudon's  Magazine of  Natural History,  (vol. iv. p. 434,) an experi-
enced entomologist, Mr.  J. O. Westwood, has given descriptions and figures, not
only of dimidiate hermaphrodites, (the example is  the Bombyx Penii) but also of
quartered hermaphrodites : the latter singular condition is exemplified in a speci-
men of the Bombyx castrensis, in which the right wing, left antenna, and left side
of the abdomen are "male; the  left wing, right antenna, and right side of the
abdomen are female; and again in a specimen of the stag-beetle (Lucanus Cervus),
in which the left jaw and right ely trum are masculine, and the right jaw and left
elytrum feminine.   In most dimidiate hermaphrodites the left side is masculine;
but an example of the contrary has been observed  in  Sphinx Populi. It is to be
regretted that the condition of the internal organs of generation cannot be  ascer-
tained in the above singular examples ; but this deficiency is in  some degree
supplied by the results  of Dr. NichoU's dissection of a hermaphrodite lobster,
(Phil. Trans., xxxvi., p. 290,) in which a testis was found  on that side of the
body which exhibited externally  the male characteristics, and an ovarium  on the
opposite side.]
   | Quere: Is there ever, in the genera of animals that are natural hemaphrodites, a
separation of the  two parts forming distinct sexes?   If there is,  it may account
for the distinction of sexes ever having happened.a


   a [The separation of the two sexual organs from one another  in the same body
occurs in many of that class  of natural  hermaphrodites which we have termed
 'allotnandrous;'  and there are many examples in the Hunterian  collection
 showing the fact.   What, therefore, Mr. Hunter seems here to refer to  is a spon-
 taneous fission of the body in the interval separating the two sexual parts, so that
 one portion of the body shall contain the male  and the other the  female organs.
 Some annellides, as  the Nais, exhibit the phenomenon of spontaneous fission,
 but the separation never occurs so as to divide the two sexual organs from one
 another, and appropriate one to each division; and were even such an occurrence
 to be supposed ever to take place, the application of the fact to explain the occur-
 rence of the distinct sexes in the naturally dioecious classes seems more worthy
 of a speculatist of the Lamarckian  school than of a sober observer of Nature.] 
OF THE FREE-MARTIN.
73
from the distinct sex to the most exact combination of male and
female organs.   This, I fancy, happens most rarely in  the human
species, never having seen  an instance.  I can  say the  same  of
dogs* and cats, with which last, however, I am less acquainted;
but in the horse, ass, sheep, and black cattle it is very frequent.
  There  is one part common  to both the male and female organs
of generation in all animals which  have the sexes distinct: in the
one sex it  is called  the penis, in the other the clitoris;  its specific
use in both is to continue, by  its  sensibility, the action excited in
coition till the paroxysm alters the sensation.   In the female it pro-
bably answers no other purpose ;  but  in the male it is  more com-
plicated, to adapt it for the purpose of conducting and expelling
the semen that has been secreted  in consequence of the actions so
excited.
  Though the unnatural hermaphrodite be a mixture of both sexes,
and  may possess the  parts peculiar to each  in  perfection, yet it
cannot  possess  in  perfection that part  which is common to both.
For as this common part is different in one sex from what it is  in
the other, and it  is impossible  for one animal to have both a penis
and clitoris, the common part must of course partake of  both sexes,
and consequently render the hermaphrodite so far incomplete ; but
these parts  peculiar to each sex may  be  perfectly joined in the
same animal, which will convey an idea of the truest hermaphro-
dite.t  Although  it may not be necessary, to constitute  an herma-
phrodite, that the parts peculiar to  the  one sex should  be blended
with those of the other, in the same way that the penis is  with the
clitoris, yet this  sometimes takes  place  in parts whose  use  in  the
distinct sexes is somewhat  similar, the testicle and  ovarium some-
times forming one  body,  without the properties of either.   This
compounded part in those animals that  have the  testicle  and
ovarium differently situated is generally found in the place allotted
for the ovarium; but in such animals as have the testicle and ova-
rium in the same situation, as the  bird  tribe, the  compound of the
two, when it occurs, will also be found in that common  situation.
  The parts of the female appropriated for the purpose of supplying
the young with nourishment are variously placed in different  ani-
mals.  In  the horse, black cattle, sheep, and other  graminivorous
animals, their situation is  between  the  hind legs; and this being
also the place allotted for the testicles of the male of this tribe, and
probably of all those in which  the testicles  come out of the cavity
of the belly; in the hermaphrodite therefore, which has both these

  * [For an example of hermaphroditism in a dog, see Phil. Trans., lxxxix. p. 157.]
i"~ f [In a recent work on hermaphroditism, by Geoffroy St. Hilaire, a mechanical
reason is assigned for the non-existence of  a penis and clitoris in the same indi-
vidual, viz., because both parts arise  from the same points of the pelvis: but in
many animals neither the  one nor the other has any bony attachment, and the
explanation above  given, founded on the similarity of their functions, is more
philosophical and satisfactory.]
                                8 
74
HUNTER ON THE ANIMAL CECONOMY.
parts, the testicles must to a certain degree descend into the udder,
though that cannot receive them so readily as the scrotum.
  The hermaphrodites which I have seen have  always appeared
externally and at first view to be females, from the penis  being the
part principally deficient, and there being an opening  behind  like
the bearing in "the female; and as the testicles in  such  hermaphro-
dites seldom come down, the udder is  left to  occupy its proper
place.  In animals the female of which is preserved for breeding
only, as sheep, goats, pigs, &c, these are generally kept, from their
being supposed to be females.
  Among horses  such hermaphrodites  are very frequent: 1 have
seen several,  but never dissected any.  The most complete was one
in which the  testicles had come down out of the  abdomen into the
place where the udder should have been (viz., more  forward than
the scrotum), and, though not so  pendulous  as  the  scrotum in the
perfect male of such animals, had alb the appearance of an udder.
There were also two distinct nipples, which, although they exist in
the male, have no perfect form, being blended with the  sheath or
prepuce, of which there was none here.   The external female parts
were exactly similar to those of the perfect  female;  but instead of
a common-sized clitoris, there was one about five or six inches long,
which when erect pointed almost directly backwards.
  I procured a foal-ass, very similar in  external appearance to the
horse above-mentioned, and killed it to  examine the parts.   It had
two nipples, but the testicles were not come down as in the above,
owing perhaps to the  animal's being yet  too young.  There was
no penis passing round the pubis to the belly, as in the perfect male
ass.
  The external female parts were similar to those of the she-ass.
Within the entrance of the vagina was placed the clitoris; but much
longer than that of a true female, it measuring about  five inches.
The vagina was pervious a little  beyond the opening of the urethra
into it, and from thence up to the fundus of the uterus there was no
canal.   The  uterus was hollow at the fundus, or had a cavity in it,
and then divided into two horns, which were also pervious. Beyond
the termination of the two horns were placed the ovaria as in the
true female;  but I could not find  the Fallopian tubes.   From the
broad ligaments, to the edges of which the horns  of  the uterus and
ovaria are attached, there passed towards each groin a part similar
to the round  ligaments in the female, which were  continued  into
the rings of the abdominal  muscles; but with this  difference, that
there accompanied them a process or theca of the peritoneum, simi-
lar to the tunica  vaginalis communis in  the male  ass; and in these
 thecae were found the testicles, but I could not  observe any vasa
 deferentia  passing from them.
   Here then were found, in the same animal, the parts peculiar to
 each sex (although very imperfect), and that part which is common
 to  both, but  different in  each, was  a kind of medium of that
 difference. 
OF THE FREE-MARTIN.
75
  Something similar to the above I have seen in sheep, goats, &c;
but I shall not at present trouble  the  reader with a description of
hermaphrodites in general, as it is a very extensive subject, admit-
ting of great variety, which would make them appear a production
of chance; whereas the intention of this account is to  point out a
circumstance which takes place in the production of  hermaphro-
dites in black cattle that appears to be almost an established prin-
ciple in their propagation, and is perhaps peculiar to  that  species
of animal.
  It is  a fact known, and I believe almost universally understood,
that when a cow brings forth two calves, and one of them a bull-
calf and the other to appearance a cow, that  the  cow-calf is unfit
for propagation, but the bull-calf grows up into a very  proper bull.
Such a cow-calf is called  in this  country a  free-martix, and is
commonly as well known among the farmers as either  cow or bull.
Although it will appear, from the description of this animal, that it
is an hermaphrodite (being in no respect different from other herma-
phrodites), yet I shall retain the term, free-martin, to distinguish the
hermaphrodite produced in this way from those which resemble the
hermaphrodite of other animals; for f know  that in  black cattle
such a  deviation may be  produced without the  circumstance of
twins :  and  even where there are twins, the one male  the  other a
female, they may both have  the  organs of generation perfectly
formed.   But when I speak of those which are  not  twins, I shall
call them hermaphrodites: the only circumstance worth our notice
being a singularity  in the  mode  of  production of the  free-martin,
and its  being, as far as I  yet know, peculiar to black cattle.
   This calf  has all the  external marks of  a cow-calf, similar  to
what was mentioned in the unnatural hermaphrodite, viz., the teats
and the external female  parts called  by farmers the bearing; and
when they are  preserved  by those who know the above fact, it is
not for  propagation, but  for  all the  purposes of an ox or spayed
heifer, viz., to yoke with the oxen  and to fatten for the table.*
   It is known that they  do not breed; they  do not show the least
inclination of the bull, nor does the bull ever take the least notice
of  them.f   They very much resemble, in form, the ox or spayed
heifer,  being considerably larger  than either the bull or the cow,
having the horns very similar to the horns of an ox.
   The  bellow of the free-martin is similar to that of an ox, having
more resemblance to that of the cow than of the bull.  Free-mar-
tins are  very  much disposed  to  grow fat with good food.  The
flesh, like that of the ox or spayed heifer, is generally much finer
in the  fibre  than either the bull or cow, is supposed to  exceed that
of the  ox and heifer in delicacy of flavour, and bears a higher price
at market.

  * I need hardly observe here, that if a cow has twins, and they are both bull-
calves, that they are in every respect perfect bulls; or if they are both cow-calves,
they are perfect cows.
  f Vide Leslie on Husbandry, pp. 98, 99. 
76
HUNTER ON THE ANIMAL CECONOMY.
   However, it  seems  that this is  not universal, for I was lately
 informed by Charles Palmer, Esq., of Luckley in Berkshire, that a
 free-martin having  been killed in  his neighbourhood, from  the
 general idea of its  being better meat than common, every neigh-
 bour bespoke a piece, which turned  out nearly as bad as bull-beef;
 worse, at  least, than that of a cow.   It  is  probable  that  circum-
 stance might arise from this animal having more the properties of
 a bull than the cow, as we shall see hereafter that they are some-
 times more the one than the other.*
   Although what  I have advanced  with  respect to the production
 of free-martins be in general true, yet, by the assistance of Benja-
 min Way, Esq., of Denham, near Uxbridge, who knew my anxiety
 to  ascertain this  point, I was lately  furnished  with an instance
 which proves that it does not invariably hold good.
   One of his cows having produced twins,  which were to appear-
 ance male and  female,  upon a supposition  that the cow-calf was a
 free-martin, he obligingly offered either to give it me, or to keep it
 till  it grew up, that we  might  determine the fact: as I conceived it
 to be a free-martin, and was to have the liberty of examining it after
 death, I desired that he would keep it; but, unfortunately, it died at
 about a  month  old.   Upon examining the organs of generation,
 they appeared to be  those of the female, and perfectly formed; but
 to make  this  more certain, I procured those of a  common cow-calf,
 and comparing them  together, found them exactly alike.  This
 made us  regret that the animal had  not lived to an age that might
have determined if it was capable of breeding; for the construction
 of the parts being  to appearance perfect, is not sufficient of itself to
 stamp it  a true or  perfect female; as I can suppose that the parts
 being perfectly formed, but without  the power of propagation, may
 constitute the most simple kind of hermaphrodite.  It is, however,
 most probable  that  this was a perfect female, which is an excep-
 tion to  the  common rule; and I have been informed  there  are
instances of such twins breeding/}-   If there are  such deviations, as
 of twins  being  perfect  male and  female, why should there not be,
 on the other  hand, an hermaphrodite  produced  singly, as in other
 animals ?  I  had the examination of  one  which seemed, upon the

  * The Romans called the bull, taurus; they, however, talked of taurae in the
feminine gender.  And Stephen observes, that it was thought the Romans meant
 by taurae, barren cows, and called them by this name because they did not con-
 ceive. He also quotes a passage from Columella,  lib. vi. cap. 22, "and like the
 turae, which occupy the place of fertile cows, should be rejected, or sent away."
 He  likewise quotes  Varro, De Re Rustica, lib. ii. cap. 5, "The cow which is
 barren is called taura."  From which we may  reasonably conjecture that the
 Romans had not the idea of the circumstances of their production.
  f [An instance of  this nature is recorded  in  the fifth volume of Loudon's
 Magazine  of. Natural  History, p. 765. "Jos. Holroyd, Esq., of Withers, near
 Leeds, had a cow which calved twins, a bull-calf and a cow-calf.  As popular
 opinion was against the cow-calf breeding,  it  had been considered a free-martin
 Mr. Holroyd was determined to make an experiment of them, and reared them
 together.  They copulated,  and in due time the heifer brought forth a bull-calf
 and she regularly had  calves for six or seven years afterwards."] 
OF THE FREE-MARTIN.                  77
strictest inquiry, 1o have been a single calf; and I am  the more
inclined to think this  true, from  having found a number of her-
maphrodites among black cattle, without the circumstances of their
birth being ascertained.
  Hermaphrodites are to be met with in sheep;  but, from the
account given of them, I should  suppose  that  they are not free-
martins.   I have  seen several which were supposed to be her-
maphrodites, but which were  imperfect males,  having  the penis
terminating in the perinaeum, the orifice of which appeared like the
bearing in the female.  Such are  not  naturally stimulated to put
themselves in the position of the female when they void their urine,
so that when it passes the surrounding parts are wetted by it, and
being covered with wool, and retaining the  urine, keeps them con-
tinually moist, and  gives  the  animal a strong smell.   They are
mentioned as both male and female.
  I believe it had never been even conjectured,notwithstanding all
these peculiarities, what was the  true nature  of the free-martin;
and  from the singularity of the  animal, and  the  account of its
production, I was almost tempted to  suppose  the whole a vulgar
error.   Yet by the universality of the testimony in its favour, it ap-
pearing to have some foundation, I eagerly sought for  an oppor-
tunity to see and examine them.   I have succeeded in this inquiry,
and have seen several, the first of which was one belonging to John
Arbuthnot, Esq., of Mitcham, and was calved in his own farm.  He
wras so obliging as to allow me to satisfy myself, first by permitting
a drawing to be made of the animal while alive, which was executed
by Mr. Gilpin, and afterwards to examine the parts when the animal
died.   At the time the  drawing was made of Mr. Arbuthnot's free-
martin, John Wells, Esq., of Bickley Farm, near Bromley in Kent,
was present, and  informed  us that a  cow of his had calved two
calves, one of which was a bull-calf, and the other a cow-calf.  I
desired Mr. Arbuthnot to request Mr. Wells to keep them, or let me
buy them of him ; but from his great desire of  natural knowledge,
he very readily consented  to preserve both till the bull showed all
the signs of a good  bull; and when the free-martin  was killed, he
allowed me to inspect the parts.
  Of all the specimens which I have  dissected, I shall only give
the descriptions  of  the three which point  out  most  distinctly the
complete  free-martin with  the gradations  towards  the male and
female.
       THE DESCRIPTION OF THE  THREE FREE-MARTINS.


            Mr. Wright's Free-Martin, five years old.

  This animal had more  the appearance and general character of
the  ox, or  spayed heifer, than of either the bull  or  cow.  The
vagina terminated in a blind end, a little way beyond  the opening
                               8* 
78
HUNTER ON THE ANIMAL CECONOMY.
of the urethra, from which the vagina and uterus were impervious.
The uterus, at  its extreme part, divided into two horns.   At the
termination of the horns were placed the testicles, instead of the
ovaria, as is the case in the female.  The reasons why I call these
bodies testicles, are the following.   First, they were above twenty
times larger than the  ovaria of the cow,  and nearly the size of the
testicles of the bull, or rather of those of the ridgil, the bull whose
testicles never come down.   Secondly, the spermatic arteries were
similar to  those of the bull, especially of the  ridgil.  Thirdly, the
cremaster muscle passed up from the rings of the abdominal muscles
to the testicles, as it does in the ridgil.*
  There were the two bags placed behind, between the bladder and
the uterus.  Their ducts opened into the vagina, a very little way
beyond the  opening of the  urethra;  but  there was  nothing similar
to the  vasa deferentia.
  As  the  external parts had  more  of the  cow than  the bull, the
clitoris, which  may be reckoned an external part, was also similar
to that of the cow, not at all in a middle state, between the penis  of
the bull and the clitoris of the  cow, as  I have described in the her-
maphrodite horse.   There were four teats:  the  glandular part  of
the udder was  but small.
  This animal  cannot be said  to  have been  a mixture of all the
parts of both sexes, for the clitoris had nothing similar to the penis in
the male, and it was deficient in the female parts, by having nothing
similar to the ovaria ; neither had the uterus a cavity.

                  Mr. Arbuthnot's Free-Martin.\

  The  external parts were rather smaller than in the cow.  The
vagina passed on, as  in the cow, to the opening of the urethra, and
then it began to contract into a small canal, which passed on to the
division of the uterus into the two horns, each horn passing along
the edge of the broad ligament laterally towards the ovaria.
  At the  termination of these  horns were  placed  both the ovaria
and the testicles ;  they were nearly of  the same size, and about  as
large as a small nutmeg.
  To the ovariaj I could not find any Fallopian tube.
  To  the  testicles were vasa  deferentia, but they were  imperfect.
The left one did not reach near to the testicle ; the right only came

  * Although I call these bodies testicles, for the reason given, yet they were
only imitations of them, for when cut into  they  had nothing of the structure of
the testicle; not being similar to anything in Nature, they had more the appear-
ance of disease.   From the seeming imperfection of the animal itself, it was not
to be supposed that they  should be testicles ; for then  the animal should have
partaken of the bull, which it certainly did not.
  f This animal  was seven years old ; had been often yoked with the oxen •  at
other times went with the cows and bull; but never showed any desires'for
either the one or the other.
  X [It is probable that these bodies were, as  in  the case previously noted  re-
mains of the corpora Wolffiana.] 
OF AN EXTRAORDINARY PHEASANT.           79
close to it, but did not terminate in a body called the epididymis.
They were both  pervious, and opened into the vagina  near  the
opening of the urethra.
  On the posterior surface of the bladder, or between the uterus and
bladder, were the two bags, called vesiculae seminales in the male,
but much  smaller than what they are in the bull; the ducts  opened
along with the  vasa deferentia.  This was more entitled  to  the
name of hermaphrodite than the first or third, for it had a mixture
of all the parts,  though all  were imperfect.

                   Mr. Wells's Free-Martin.
  This animal was between three and four years old when  killed;
and had never been observed to show any signs  of desire  for  the
male, although it went constantly with one; and looked more like
a heifer than free-martins usually do.
  The teats and udder were small compared with those of a heifer,
but rather larger than in either of the former examples; the begin-
ning of the vagina was similar  to that  of  the cow, but soon ter-
minated a little  beyond the opening of the  urethra, as in the first-
described.  The vagina and uterus, to external  appearance, were
continued, although  not pervious, and the uterine part divided into
two horns, at the  end of which  were the ovaria.
  I could not observe in this animal any other body which I could
suppose to be the  testicle.
  There was on the side of the uterus an interrupted vas deferens
broken off in several places.
  Behind the bladder, or between that  and the  vagina, were  the
bags called vesiculae seminales, between which were  the  termina-
tions of the two vasa deferentia.
  The ducts of  the bags, and the vasa deferentia, opened as in  the
last instance.
  This could not be called an exact mixture of all the parts of both
sexes, for here was no appearance of testicles.
  The female parts were  imperfect, and  there  was the addition
of part of the  vasa  deferentia, and the  bags called  vesiculae
seminales.
  This  circumstance  of  having no testicles, perhaps,  was the
reason why it had more the external  appearance of a heifer than
what  they commonly have,  and  more than either  of the two
former.
4. AN ACCOUNT OF AN EXTRAORDINARY PHEASANT.

  Every deviation from  that original form  and structure which
gives the distinguishing  character  to the productions of Nature,
may not improperly  be  called  monstrous.   According to  this 
80
HUNTER ON THE  ANIMAL CECONOMY.
 acceptation  of  the term,  the variety of  monsters will be  almost
 infinite ;* and, as far as my knowledge has extended, there  is  not
 a species of animal, nay, there  is not a  single part of  an  animal
 body, which is not subject to an extraordinary formation.
   Neither does  this appear to be a matter of  mere chance ; for  it
 may be observed that every species has a disposition to deviate from
 Nature  in a manner  peculiar  to itself.f   It  is  likewise worthy of
 remark, that each species of animals is disposed to have nearly the
 same sort of defects, and to have  certain supernumerary parts of
 the  same kind:  yet every part is not alike  disposed to  take  on  a


   *  [Mr. Hunter attempted, notwithstanding, to reduce this variety of monsters
 to definite groups, and left  the following  outline of a classification of monsters,
 in an explanatory  introduction to  the extensive series of those objects in his
 collection:
     " 1.  Monsters from preternatural situation of parts.
     " 2.-------------addition of parts.
     " 3.  ----    ■----deficiency of parts.
     " 4.-------------combined addition and deficiency of parts, as in herma-
                           phroditical  malformation."
   Licetus,a Huber,b and Malacarnec  had proposed  classifications of monsters
 prior to the time of Hunter, all of which are more or less tinctured  with the
 superstitions of the times; thus, the tenth class in the system of Licetus is appro-
 priated to the offspring of the  illicit  intercourse  of demons with women: the
fifteenth of Malacarne contains  the brutes with human  members, &c.   Blumen-
 bach, towards the xend of the eighteenth  century, published an arrangement  of
 monsters which closely resembles that of Hunter; he, however, distinguishes,
 but without sufficient reason,  unnatural hermaphrodites  from  monsters, and
 divides the latter into
     " 1.  Monsters by an unnatural conformation of certain parts of the body,—
            Fabrica aliena.
     " 2.-----------transposition of  parts,—Situs mutatus.
     " 3.-----------a deficiency of parts,—Monstraper defectum.
     " 4.-----------supernumerary parts,—Monstra per excessum."
   The study of the various congenital aberrations from the specific form presented
 in the different classes of the animal kingdom, has since been ably and' success-
 fully pursued by Meckel, Geoffroy St.  Hilaire, Otto, Breschet, Charuet, &c, the
 general results of whose labours may be found in the Histoire Generate et Particu-
 liere des Anomalies  de VOrganization chez  f Homme et les Animaux, ou Traite  de
 Teratologic, by Isid. Geoffroy Saint-Hilaire :  8vo, 1832.]
   f  [The value of the principle  here  enunciated will be appreciated, when it is
 stated that it is the basis of the latest  and most elaborate work on the subject of
 monsters.  It is  claimed for Geoffroy St. Hilaire  as the most important of his
 deductions in Teratology, and the chief point in which his  system differs from,
 and  is superior to, those of his  predecessors.  " C'est de  principes precisement
 inverses  que mon pere a pris sur point de depart; et  c'est aussi, comme cela
 devait etre a des resultats inverses qu'il est parvenu.  Etablissant, par un grand
 nombre de recherches, que les  monstres  sont, comme les  etres  dits  normaux,
 soumis a des regies constantes,il est conduit aadmettre que la methode declassi-
 fication que les naturalistes emploient  pour les seconds, peut etre appliquee avec
 succes aux premiers." Isid. Geoffroy St.-Hilaire, loc. cit., p. 99.]

   » Fortunius Licetus, De Monstris, ex reccnsione G. Blasii: Amstelodami, 1665,
 4to.
   i>  Observationes nonnulke de Monstris.- 4to. Cassel, 1748.
   <= " De' Mostri umani de' Caretteri fondamentali su cui ne se portrebbe stabilire
 la Classificazione," Mem. della Soc. Ital, torn. ix. 4. 
OF  AN EXTRAORDINARY PHEASANT.
81
great variety of forms; but each part of each species seems to have
its monstrous form originally impressed upon it.*
  It is well known that many orders of animals have the two parts
designed for the purpose of generation different in individuals of
the same species, by which  they are distinguished into male and
female;  but this is not the only mark of distinction, in the greatest
part the male being distinguished from  the female by various other
marks.   The varieties which are found Hn the parts of generation
themselves  I shall call the first or principal marks, being originally
formed  in  them, and belonging equally to  both sexes; all  others
depending upon these I shall call secondary, as not taking place till
the first  are becoming of use, and being principally, although not
entirely, in  the male.
  One of the most general marks is, the superior strength of make
in the male ;  and another circumstance, perhaps equally so,  is this
strength being directed to one part more than another, which part
is that most immediately  employed in fighting.  This difference in
external form is more particularly remarkable in the animals whose
females  are of a peace-able  nature, as are the greatest number of
those which feed  on vegetables, and the marks to discriminate the
sexes are in them very numerous.   The males of almost every class
of animals are probably disposed to fight, being, as I have observed,
stronger than the females;  and in  many of these there are parts
destined solely for that purpose, as the spurs  in the cock, and the
horns in the bull; and on that account  the  strength of the bull lies
principally in his neck ; that of the cock in his limbs.
  In  carnivorous animals, whose prey is  often of a  kind  which
requires strength  to  kill, we  do not find  such  a  difference in the
form  of the male and female, very little being discernible in the dog
and bitch, in the he or she cat, or in  the cock and hen of the eagle, f
A difference, however, is  often perceivable in the whole or in some
part of their external covering; the mane of the lion distinguishing
him from the lioness; and the males of such animals as neither fight
nor feed on flesh, being  only distinguishable from the female  by
some peculiarity in   the covering of their bodies, as the cock  and
hen in many birds.   The male of the human  species is distinguished

  * [In this principle Mr. Hunter is opposed to Geoffroy St.-Hilaire, who attri-
buted the  production (I'ordonnee) of monstrosities to  the operation of exterior or
mechanical causes at some period of foetal development.  Defective formation in
parts of a  fcetus has indeed been produced by destroying a portion of the  respira-
tory surface of an  egg during  incubation; but  this  result by no  means affords
adequate grounds for assigning as the sole cause of every malformation accidental
adhesions between the fcetus and its coverings.  Mr. Hunter also made experi-
ments with reference to monstrosities, and succeeded in effecting what, at first
sight,  seems the most difficult  to produce, viz., the monsters by excess, of which
several specimens of' Lacerta, with a double tail (No. 2219—2223), afford exam-
ples.  It  is evident, however, from the expression in the concluding paragraph
of the text, that he regarded the cause'of congenital malformation as existing in
the primordial germ.]
  | [The  difference in the size of the two sexes is sufficiently marked in most of
the Raptorial birds; but it is the female which has the advantage in this respect.] 
82
HUNTER ON THE ANIMAL CECONOMY.
from the female both by his  general strength and his covering, as
also by a difference of voice.
  In these orders of animals whose sexes are distinct, we may not
only observe the genital organs to be subject to mal-conformation,
as in any other part of the animal, but that an attempt is sometimes
made to unite the two organs in the  same  animal body, making
what may  be called  an  unnatural hermaphrodite.  In producing
the unnatural hermaphrodite the same  laws seem to operate as in
the mal-conformation of other parts of animals; it being observable,
that these deviations obtain through a whole species precisely in the
same manner.  I have already given an account of the free-martin,
which exhibits a mixture of the two  parts of generation in  the
same animal.
  It is my intention at present to extend my inquiry on this subject
no further than what relates to the resemblance which one sex bears
to another in those distinguishing properties which I term secondary;
for we find that there is often a change of the natural properties of
the female sex into those of the secondary of the male ; the female,
in such cases, now and  then assuming the secondary peculiarities
of the male.  It is to be observed, that  some classes are more liable
than others to this change, a singular example of which is to be the
subject of the following pages.
  To bring  the foregoing observations into  one point of view,  I
here beg leave to remark, that in animals just born, or very young,
there are no peculiarities to  distinguish one sex from the other, ex-
clusive of what relates to the organs of generation, which  can only
be in those who  have external parts;  and that towards the age of
maturity the discriminating changes  before mentioned  begin to
appear; the  male then losing that resemblance he had to the female
in various secondary properties ;* but that in all animals which are
not of any distinct  sex, called hermaphrodites, there  is  no  such
alteration taking place in their  form when they arrive at that age.
It is evidently the male which at this time in such respects recedes
from the female, every female being  at the age of maturity more
like the young of the  same species than the male is observed to be;
and if the male  is  deprived of his testes when young, he retains
more of the original  youthful form, and  therefore more resembles
the female.
   From hence it might be supposed that the female character con-
tains more truly  the specific  properties  of the animal than the male;
but the character of every animal is that which  is  marked by the
properties common to both sexes, which are  found in a natural
hermaphrodite, as in a snail, or  in animals of neither sex, as the
castrated male or spayed  female.
   But where the sexes are  separate,  and  the animals have  two

  * This is not common to all animals of distinct sexes, for in fishes there is no
great difference ; nor in many insects ; nor in dogs, as has been already observed :
however, it is considerable in many quadrupeds, but appears to be most so in
birds. 
OF AN EXTRAORDINARY PHEASANT.
83
 characters, the one cannot more than the other be called the true,
 as the real distinguishing marks of each particular species, as has
 been mentioned above, are those common to both sexes, and which
 are likewise in the unnatural  hermaphrodite.  That these properties
 give the distinct character of such animals is evident, for the  cas-
 trated male and the spayed female have both the same common
 properties;  and when I  treated of the free-martin, which  is a
 monstrous hermaphrodite, I  observed  that  it was  more like the
 ox than the cow or bull;  so  that the marks characteristic  of the
 species which  are found in  the  animal  of a  double  sex are
 imitated  by depriving the individual of certain  sexual  parts, in
 consequence of which it  retains only the  true properties  of the
 species.
   They are  curious facts in the natural history of animals, that by
 depriving either sex of the true parts  of generation, they shall seem
 to approach  each other in appearances, and acquire a resemblance
 to the unnatural hermaphrodite.
   In some species of animals that have the secondary properties we
 have mentioned, there is a deviation from the general rules, by the
 perfect female, with respect to the parts of  generation, assuming
 more or less the secondary character of the male.
   This change does not appear to arise from any action produced
 at the first formation  of the animal, and in this respect is similar to
 what takes place in the male; neither  does  it grow up with the
 animal  as it does to a certain degree in the male, but seems to be
 one of those  changes  which happen at a  particular period, similar
 to  many  common  and natural phenomena:  like to what is ob-
 served of the horns of the  stag, which differ at different  ages;
 or to the mane of the  lion, which does not grow till  after his  fifth
 year, &c*
   This  change has  been observed in  some  of the bird tribe, but
 principally in the common pheasant;  and it has been  observed by
 those who are  conversant with this bird, when wild, that there
 every now and then appears a hen pheasant with the feathers of a
 cock: all, however, that they have described  on the subject is, that
 this animal does not breed, and that its spurs do not grow.  Some
 years ago one of these was sent to the late Dr. William Hunter,
 which I examined, and found it to have all the parts peculiar to the
 female of that bird.  This specimen is still preserved in Dr. Hun-
 ter's museum.
  Dr. Pitcairn having received a pheasant of this kind from  Sir
 Thomas Harris, showed  it  as a curiosity to Sir Joseph Banks
 and Dr. Solander.  I  happening to be  then  present, was  desired
 to  examine  the bird, and the  following was  the  result  of  my
 examination.
  I found the parts  of generation to be truly female, they being as

  * [We have observed in the young African lions at the Zoological Gardens
that the mane began to be distinctly developed at the third year, and was com-
pleted at the fourth.] 
84            HUNTER ON THE ANIMAL CECONOMY.
perfect as in any hen pheasant that is not in the  least prepared for
laying eggs, and having both the ovary and oviduct.
  As the observations hitherto  made have been  principally upon
birds found wild, little  of their history can  be  known ;  but from
what took place in a hen  pheasant, in the  possession of a  friend
of Sir Joseph Banks, it appears  probable  that  this change of cha-
racter takes place at an advanced period of the animal's life, and
does  not grow up with  it from  the beginning.  This lady, who
had for some time bred  pheasants, and  paid particular  attention
to them, observed that  one  of the  hens,  after having produced
several broods, moulted, when the  succeeding feathers were ihose
of a  cock, and that this animal was never afterwards impregnated.
Hence it is  most probable that all the hen pheasants found wild,
having the feathers of a cock, were formerly perfect hens, but have
been  changed by  age,  or perhaps  by certain  constitutional cir-
cumstances.*
  Having bought  some pheasants  from a  dealer  in  birds, among
which were several  hens, I perceived, the  year after, that one of
the hens did not lay, and that  she began  to change her feathers.
The  year following she had  nearly the plumage of the cock, but
less brilliant, especially on the head ; and it is more than probable
that  this was  an old hen, nearly under circumstances  similar to
to those  before described.
  Lady  Tynte had a favourite pied pea-hen which had produced
chickens eight several times; having  moulted when about  eleven
years  old, the lady and family were  astonished by her displaying
the  feathers  peculiar to the other sex, and appeared like a pied
peacock. In this process the tail, which became like  that of the
cock, first made its appearance after moulting ; and in the following
year, having moulted again, produced similar feathers.   In the third
year she did the same, and, in addition, had spurs  resembling those
of a cock.   She never bred after this change in her plumage, and
died  in the following winter during the hard  frost in the year 1775-6.
This bird is  now preserved in the  museum of the late  Sir Ashton
Lever.f
  From what has been related of these three birds, we may con-

  * [The cause of the change in the plumage which Mr. Hunter here alludes to,
has been proved by subsequent dissections to be effective and  not uncommon. See
the paper  entitled ' On the change in the Plumage  of some  Hen-Pheasants,' by
Wm. Yarrell, Esq., Phil. Trans. 1827, in which the author states, that "certain
constitutional  circumstances producing this change may, and do occur, at any
period during  the life of the fowl, and that they  can be produced by artificial
means."]
  ■f It might be supposed that this bird was really a cock which had been sub-
stituted for the hen ; but the following facts put  this matter beyond a doubt.
First, there was no other pied pea-fowl in the country.  Secondly, the hen had
nobs  on her toes, which were the  same after her change.  Thirdly, she was as
small after the change as before, therefore too small for a cock.  Fourthly, she
was a favourite bird, and was generally fed by the lady, and used to come for her
food, which she still continued to do after the change in the feathers. 
OF THE OVARIA.
85
elude, that this change is merely the effect of age, and obtains to a
certain degree in every class of animals.   We find something similar
taking place even in the human species ; for that increase of hair
observable on the faces of many women in advanced life is an ap-
proach towards the beard, which is one of the most distinguishing
secondary properties of man.
  Thus we see  the  sexes which, at an early period, had little to
distinguish  them from  each other, acquiring  about the  time of
puberty secondary properties, which clearly characterize the male
and female, the male at this time receding from the female, and as-
suming the secondary properties of his sex.
  The female, at a much later time of life, when the powers of pro-
pagation cease, loses many of her peculiar properties, and may be
said, except from mere  structure of parts, to be of  no sex, even re-
ceding from the original character of the animal, and approaching,
in appearance, towards the male, or perhaps more properly towards
the hermaphrodite.
5. AN EXPERIMENT TO DETERMINE THE EFFECT OF
     EXTIRPATING ONE OVARIUM UPON THE NUMBER
     OF YOUNG PRODUCED.*

  In all animals of distinct sex, the females, those of the Bird-kind
excepted, have, I believe, two ovaria, and of course the oviducts are
in pairs.
  By distinct sex  I mean when the parts destined to the purposes
of generation are of two kinds, each kind  appropriated to  an in-
dividual of each species, distinguished by the appellation of male and
female, and equally necessary to the  propagation of the animal.
The testicles, with their appendages,  constitute  the  male ,d the
ovaria, and their appendages, the female sex.
  As the ovaria are the  organs which, on the  part of the female,
furnish what  is necessary towards the production of the third, or
young animal, and as females appear to have  a limited portion of
the middle stage of life  allotted for that purpose, it becomes a question,
whether those organs are worn out by repeated acts of propaga-
tion ; or whether there is not a natural and constitutional period to
that power on their part, even if such power has never been exerted 7
If we consider this subject in every view, taking the human species
as an example, we  shall discover that circumstances, either local or
constitutional, may be capable of extinguishing in the female the
faculty of propagation.   Thus we may observe when a woman
begins  to breed at an early period, as at fifteen, and has her children

  * [Originally published in the Philosophical Transactions, vol. lxxvii., p. 233 ;
read, March 22, 1787.]
                              9 
86
HUNTER ON THE ANIMAL CECONOMY.
fast, that she seldom breeds longer than the age of thirty or thirty-
five; therefore we may suppose either that the parts are then  worn
out, or that the breeding constitution is over.   If a woman begins
later, as at twenty or twenty-five, she may continue to breed to the
age of forty or more:  and there are,  now and then, instances of
women who, not having  conceived  before, have had children  as
late in  life as at fifty years  or  upwards.  After that period few
women breed, even though  they should  not  have bred  before;
therefore there must be a natural period to the power of  concep-
tion.  A  similar stop  to  propagation  may likewise take place in
other classes of animals, probably in the female of  every class, the
period  varying  according to circumstances.  But  still we are not
enabled to determine how far it depends on any particular property
of the constitution, or of the ovarium alone.
   As  the female, in  most classes of  animals, has two ovaria, I
imagined that by removing one it might be possible to  determine
how far their actions  were reciprocally influenced by each other,
from the  changes which by comparison might  be observed to take
place, either by the breeding-period being shortened, or perhaps, in
those animals whose nature it is to bring forth more than one at a
time, by the number produced at each birth being diminished.
   There  are  two views in which this  subject may be considered.
The first, that the ovaria, when properly employed, may be bodies
determined and unalterable respecting the number of young to be
produced.  In this case we  can readily imagine  that, when one
ovarium  is removed, the other  may be capable of producing its
determined number in two different ways : one, when the  remain-
ing ovarium, not influenced by the loss of the other, will  produce
its allotted number, and in the same time; the  other, when affected
by the loss, yet  the  constitution demanding the same  number of
young each time of breeding, as if there were still two  ovaria; it
must furnish  double the number it  would have been required to
supply had both been  allowed to  remain, but must consequently
cease  from the performance of its function in  half the time.   The
second view  of the subject  is,  by supposing  that there is  not
originally any fixed number which the ovarium must produce, but
that the number is increased or diminished according  to  circum-
stances;  that it is rather the constitution at large  that  determines
the number; and that if one ovarium is removed, the other will be
called upon by the constitution to perform the operations of both,
by which means the animal should produce with one ovarium the
same number of young as would have been produced if both had
remained.
   With an intention to ascertain  those points  as  far as 1 could, I
was led  to make the following experiment; and  for that purpose
gave  pigs a preference  to  any other  animal, as  being  easily
managed, producing several at a litter, and breeding perfectly well
underlhe confinement necessary for experiments.   I selected two
females of the same colour and size, and likewise a boar-big, all of
the same farrow; and, having  removed an ovarium from one of 
OF THE OVARIA.
87
the females, I cut a slit in one ear to distinguish it from the other.
They were well fed and kept warm, that there might be no impedi-
ment  to  their breeding;  and  whenever they farrowed, their pigs
were  taken away exactly at the same age.
  About  the beginning of the  year 1779 they both took the boar;
the one which had  been  spayed earlier than the perfect, female.
The distance of time, however, was not great, and they continued
breeding  at nearly fhe same times.  The spayed animal continued
to breed till  September 1783, when she was  six years old, which
was a space of more than four years.   In that time she had eight
farrows;   but did not take the boar afterwards, and had in  all
seventy-six pigs.   The perfect  one continued  breeding till Decem-
ber 1785, when she  was about  eight years old, a period of almost
six years, in which time she had  thirteen farrows, and had in all
one hundred and sixty-two pigs; after this time she did not breed:
I kept her till November 1786.
  I have  here annexed a table of the different times of each farrow,
with the number of pigs produced.
	Spayed	Sow.	
rows.	Number of youi	1S-	Time.
1	6		Dec. 1779.
2	8		July 1780.
3	6		Jan. 1781.
4	10		Aug. 1781.
5	10		Mar. 1782.
6	9		Sept. 1782.
7	14		May 1783.
8	13		Sept. 1783.
                          76
  November  following she  was put to the  boar, but  brought no
pigs.  April 1784, she was  again  put  to the boar, without effect,
and  never  was  observed to  take  the boar afterwards, although
often with him.  November 1784,  she was killed.
	Perfect Sow.	
Farrows.	Number of young.	Time.
1	9	
2	6	
3	8	
4	13	Dec. 1781.
5	10	June 1782.
6	16	Dec. 1782.
7	13	June 1783.
8	12	Oct. 1783.
                          87
Eleven pigs more  than  were produced by the spayed sow in her
eight farrows. 
88
HUNTER ON THE ANIMAL CECONOMY.
Farrows.	Number (
9	12
10	10
11	12
12	16
13	19
	75
After which she bred no more.

       The first eight farrows were
       The last five farrows were  .
                 The number from the spayed one .  .  76

     More than farrowed by the imperfect animal .  .  86

  It is observable that both sows rather increased in  their number
each time as they grew  older, although not uniformly; the differ-
ence between the first and last in both animals being considerable.
  From the above table we find that the sow with only one ovarium
bred till she was six years old, from the latter end of 1779 till Sep-
tember 1783,  about  four  years,  and in that time  brought forth
seventy-six pigs.  The perfect animal bred till she was eight years
of age; and if conception  depended  on the  ovari, we might have
expected that she would bring forth double  the  number at each
birth ;  or, if not, that she would continue breeding for double the
time.  We indeed find her producing ten more  than double  the
number of the imperfect animal, although she had not double the
number of farrows; but this may perhaps be explained by observing
that the number of young increased as the female grew  older,  and
the perfect sow continued  to breed much longer than the other.
  From a circumstance mentioned in the course of this experiment
it appears that the desire for the male continues  after the power of
breeding is exhausted in the female ; and therefore does  not alto-
gether depend on the  powers of the ovaria to propagate, although
it may probably be influenced by the existence of such parts.
  If these observations  should be  considered as depending on  ar
single experiment, from which  alone it is  not  justifiable to draw
conclusions, I have only to add that the difference in the number
of pigs produced by each was greater than  can be justly imputed
to accident, and is a circumstance certainly  in  favour of the uni-
versality of the principle I wished  to ascertain.*
   From this  experiment it seems most probable th^t  the ovaria are

  * It may be thought by some that I should have repeated this  experiment; but
an  annual expense of twenty pounds for ten years, and the necessary attention
to make the experiment complete, will be a sufficient  reason for my not having
done it.
   Time.
Feb. 1784.
June 1784.
Dec. 1784.
May 1785.
Dec. 1785.
87
75
Total .  162 
              DESCRIPTION OF THE UTERUS, ETC.            89

from the beginning destined to produce  a fixed  number, beyond
which they cannot go, although circumstances may tend to diminish
that number; but that the constitution  at  large has  no  power of
giving to one ovarium the power of propagating equal to both ;  for
in the present experiment the animal  with  one ovarium  produced
ten pigs less than half the number  brought forth by  the  sow with
both ovaria.  But that the constitution has so far a power of influ-
encing one ovarium as to make it produce its number in a less time
than would probably have been the case if both ovaria  had been
preserved, is to be  inferred from the above-recited  experiment.
 6.  THE CASE OF A YOUNG WOMAN WHO POISONED
      HERSELF IN THE FIRST MONTH OF HER PREG-
      NANCY.

    BY THOMAS OGLE, SURGEON, GREAT RUSSELL-STREET, BLOOMSBURY.

 To which is added, an Account of the Appearances after Death ;  by
                     the late  John Hunter*

   Mary Hunt, servant to a gentleman in Charlotte-street, Bedford-
 square, twenty-five years of age, had for some time shown a par-
 tiality for one of the footmen in the same family.  She became  all
 at once exceedingly  dejected, which was supposed to proceed from
 his neglecting her;  and on Thursday, the 19th of April, at twelve
 o'clock at night, took half an ounce of  white arsenic, and imme-
 diately afterwards   drank  a  quart of  wine;  about  one o'clock
 she had so much pain in  her  stomach as to be obliged to call for
 assistance.
   The symptoms were excruciating pain  in the stomach, sick-
 ness, vomiting,  excessive   thirst, and  a small tremulous  pulse;
 these were followed by pain  in the bowels, and several  purging
 stools.
   She drank brandy and water, wine and water, and several quarts
 of plain  water,  to  relieve the thirst  and ease the pain.   Some
 hours after taking the arsenic she became easier, expressed a desire
 to be left alone,  being inclined  to sleep, and remained several hours
 m a dosing or comatose state, from which she did not recover, and
 died about one o'clock on  Friday, thirteen hours after taking the
 arsenic.
  Upon  inspecting the body after death there were found the fol-
 lowing appearances.

  * [Originally published in the Transactions of  a Society for the Improvement
of Medical and  Chirurgical Knowledge, vol. ii., p. 63. Communicated to the
Society by Everard  Home, and read August 5, 1794.]
                               9* 
90           HUNTER ON THE ANIMAL CECONOMY.
  In the cavity of the  abdomen there was an  appearance of the
effects of slight inflammation on the peritoneal coat of the small
intestines.
  The stomach contained a greenish fluid, with a curdy substance in
it, in all amounting to about twelve ounces.                  ,.
  On the internal surface of the great curvature near the cardiac
a portion of the villous coat, about the size of a crown-piece, was
partly destroyed,  and  of  a dark  red colour,  with a  regularly
defined  edge,  and  some  of the  arsenic  adhering to  different
parts of its  surface.   The  rest  of the stomach was in  a na*ural
state.  This appearance in the stomach was an effect produced by
the arsenic.
 . The uterus was a little enlarged, and had the vessels unusually
loaded with  red blood.
  There was an uncommon quantity of blood in the vessels of the
ovaria and Fallopian tubes, but  principally in those of the ovarium,
and morsus diaboli of the left side.
  The organs  of generation being  carefully removed,  and  both
ovaria being slit open, there was found in the left a corpus luteum.
  It was evident, from this circumstance, that conception had taken
place; which  led to an inquiry respecting  the  last  appearance of
her menses,  which appeared by  the evidence of the family to  have
been little more than a month before  her death.
  With the  dread upon her mind of being with child, the usual
period of menstruation  had hardly elapsed without its appearing,
which confirmed her suspicions, before  she, in a fit of despair, put
an end to her life.
  From this evidence, the period of conception  could not exceed a
month, and probably was much within that time.
  As it  was interesting to have the parts accurately examined, to
see what information might  be  acquired respecting the foetus at so
early a  period, they were given to  Mr.  Hunter for that purpose,
whose observations upon  them are contained in the following
account.
   The arteries of the uterus were injected, and the smaller vessels
were filled to so great a degree of minuteness  that the whole sur-
face became extremely red.
   The cervix uteri and os tincae were of their natural size ; but the
body, or that portion of the uterus next the fundus, was a little en-
larged,  and  more prominent externally in the   middle.   The sper-
matic vessels were also enlarged.
   On cutting  into the substance of  the  uterus, it had  more of a
laminated structure than in the unimpregnated state; this appear-
ance of lamellae appeared upon examination to  be formed by veins
somewhat enlarged, compressed and transversely  divided.  The
uterus was unsually soft in texture, and terminated on the internal
surface in a pulpy substance.
   The  blood-vessels of the  uterus passed  into and ramified upon
this pulpy substance, which was continued across  at  the cervix 
              DESCRIPTION OF THE UTERUS, ETC.            91

uteri, so as to make the cavity of the uterus a circumscribed bag ;
and at this part the pulpy substance was so thin as to resemble the
retina.
  This cavity had a  smooth but irregular internal surface, and the
pulpy substance upon  which it  was  formed was evidently blood
coagulated and varied in  its thickness in different parts.  Upon a
longitudinal section of the uterus, the posterior part of the coagulum,
which was the thickest, was nearly half an inch; where it termi-
nated towards the cervix it was pendulous and unattached.  There
were also several loose processes, all turned towards the cervix, one
of them  very thin, as  broad as  a silver penny, and only attached
by one edge to the fundus  near the opening of the right Fallopian
tube.
  On slitting open the  Fallopian tubes, the coagulum was found to
pass some way into  them, and to  extend more than half an  inch
on the left side, which had the corpus luteum.  The coagulum was
thickest at the orifice of the  tube, and there adhered to the inner
surface for the eighth part of an inch;  beyond which it became
smaller and terminated in  a point.  In the left tube the coagulum
was in two places coiled or folded upon  itself, as if thrown back
by the action of the  tube.   The  portions of the  coagulum  at the
orifices of the tubes were hollow.
  When the inner surface of the cavity of the uterus was examined
with  a magnifying  glass  it  was  found  extremely  vascular, and
dotted with innumerable whitish spots  too small  to be  seen  by the
naked eye.
  In the  examination of this uterus and  Fallopian tubes, as Mr.
Hunter's chief object was  the detection of the embryo, no precau-
tion  was omitted which could be devised to  prevent it being over-
looked or destroyed.
  The uterus was opened  in a bason  of clear water, the incision
was conducted with great  circumspection, and  very slowly  con-
tinued, till the whole of the  cavity was exposed. Every part of
the  internal  surface was minutely examined  with • magnifying
glasses;  but in  no  situation was there  anything resembling an
embryo to be found.
  The presence of a  corpus luteum, the enlargement of the uterus,
the newly-formed  vascular membrane, or decidua, lining the cavity,
and  the  history of the  case, sufficiently prove conception to have
taken place ; and  the embryo being nowhere detected  by an exa-
mination  so accurate and  conducted by an  anatomist so skilful in
minute investigation, would induce  a belief that the fcetus had not
been sufficiently advanced to take on a regular form.
  The appearances  in the uterus, here described,  the late  Dr.
Hunter, in his  lectures, mentioned  to  have  seen at a  very early
period after impregnation :  so far they are not entirely new.   The
accuracy of the examination renders this case valuable, as it seems
to enable  us to decide a point hitherto  not at all  understood—that
certain changes in the uterus not  only take  place previous  to the 
92
HUNTER ON THE ANIMAL CECONOMY.
reception of the foetus, but that the fcetus does not acquire a visible
form for some time after these changes have been made.*

   * [The positive conclusions deduced from this case, viz., that certain changes
take place in the uterus within one month  after conception, have been confirmed
by all those anatomists who have enjoyed similar opportunities of examining the
uterine organs within the same period.  These changes consist essentially in the
effusion of fibrin or coagulable lymph from the villi of the lining membrane ot tlie
uterus, which villi also become much elongated and highly vascular; and minute
vessels are continued from them  into the effused lymph, forming loops or arches
in that substance.  This process is compared  by Hunter, in the following paper,
to the effusion of lymph consequent on the introduction of an extraneous living
part into any of the cavities of the body;  and Professor von  Baer, in a recent
elaborate description of the uterus of a female who drowned  herself eight days
after impregnation, makes the same comparison.  Professor Weber, in an exami-
nation of the uterus seven days after conception, also speaks of the great vascu-
larity of its inner surface, and describes the villi as consisting of small cylinders
placed perpendicularly to the  inner surface of the uterus; united by a slimy mem-
brane, and forming together a layer of a pale soft substance, from half a line to a
line in thickness; whilst in some places the cylinder presented the length of from
two to three lines.
   With respect to the negative results of Mr. Hunter's examination relative to
the reception of the foetus in the uterus, and " its acquisition of a visible form," I
suppose that the word ' fcetus' is here used to express the product of generation,
or ovum, especially as  it is stated, that  " in the examination of the uterus and
Fallopian tubes Mr. Hunter's chief object was the detection of the  'embryo.' "
Now if the product of generation were really expected  to have been seen in that
state of development which we understand by the terms embryo and fcetus, its
presence was most likely overlooked; since, from the analogy of the  dog and
rabbit, it most probably would have existed merely as a small pellucid vesicle or
ovum, supposing that it had escaped from the  ovarium; and it is to be regretted
that the expression " there was found in the left  'ovarium' a  corpus luteum " is
all the evidence on that point which the present case affords.
   In the  bitch, Von Baer has  shown that the ova pass into the Fallopian tubes on
the eight day after impregnation, and that when they reach the uterus they lie
quite free in its cavity, are perfectly transparent, of a somewhat elongated form,
and extremely delicate texture, and are from  half a  line to a  third of a line in
diameter.
   In the rabbit, the observations of De Graaf, of Prevost and Dumas, and ofCoste,
prove that the ova pass into the tubes the third  (or, according to Coste, the second)
day after impregnation; they reach the horns of the uterus  on the fourth day,
and are then  about a  line in  diameter, in  the form of pellucid bubbles, free and
moveable.
   According  to Home, the human ovum has reached the uterus on the eighth day
after impregnation, when it is described  as presenting an elliptical form, rather
more than a  line (±% parts of an inch) in length, and ^-0 parts of an inch in
breadth.  It is composed of two membranes, of which the external  is of consider-
able thickness and consistence, very little  transparent, quite smooth, and milk-
white ; the internal membrane or bag consist ' of a seemingly very thin, perfectly
smooth, and  glossy membrane, which seemed to have considerable strength.'
This internal membrane contained a thick, slimy matter, like honey, and " two
round corpuscles, apparently more  opake, and of a yellowish tint," regarded  as
" the probable seat of the future heart and brain."
   On comparing the preceding account with the observations that have been made
on the mammiferous  ovum, it will be found that the  nearest resemblance to the
supposed human ovum obtains in that of the ornithorhynchus, at least in the texture
of the two membranes described, of which the external must be regarded  as the
chorion, the internal as the membrana vitelli.  In the ornithorhynchus, as in the
ovo-viviparous reptiles, the chorion is dense and unyielding ; but in the specimens 
ON THE STRUCTURE OF THE PLACENTA.          93
      7. ON THE STRUCTURE  OF THE PLACENTA.

   The connexion between the mother and foetus in the human sub-
ject,  has in every age, in which science has been cultivated, called
forth the attention of the anatomist, the physiologist, and even the
philosopher;  but both that connexion,  and the structure of the parts
which form the connexion, were unknown till about the year 1754.
The  subject is certainly most interesting, and  the discovery im-
portant ; and it is my intention, in the following pages, to give such
an account of it as I hope may be acceptable to the public ;* while,
at the same time, I establish  my own claim to the discovery.  But
that I may not seem to  arrogate to  myself more  merit than I am
entitled to, let me in justice to  another person relate what follows.
   The late indefatigable Dr.  MacKenzie,  about the month of May,
1754, when assistant to Dr. Smellie, having procured the body  of
a  pregnant woman, who died undelivered at the full  term, had in-
jected both the veins and arteries with particular success, the veins
being filled with yellow, the  arteries with  red.f
   Having opened the abdomen,  and exposed the  uterus, he made
an incision into the fore part, quite through its substance, and came

which we examined, and which, as in Sir Everard Home's case, had been subjected
to the action of spirit, the chorion was semitransparent.   In those mammalia,
however, which approximate the human species in the placental development of
the foetus, the ovum, when it has been detected  unattached in the uterus, has
invariably presented a translucency and delicacy of its membranes, with which
the structure of the human  ovum, as described by Home, is totally at variance;
and, from the tenor of the whole  account, we believe the object to have been
what  Mr. Bauer, to whom its description and delineation were confided,a declared
it to resemble, viz., the egg of an insect.
   Rejecting, then, the description  we have just been  considering,—and its apo-
cryphal character is rightly admitted by all physiologists of the present day, who
have investigated the nature of the  mammiferous ovum,—the determination of the
period of the passage of the human ovum into the uterus after impregnation, and
its condition and structure when first received into that cavity, still  remain open
to the researches of the physiologist.]
   * This paper was read at  the Royal Society, but as the facts had before that
time been given to the public, it was not published in the Philosophical Transac-
tions.
   t Dr. MacKenzie being then an  assistant to the late Dr. Smellie, the procuring
and dissecting this woman without Dr. Smellie's knowledge was the cause of a
separation between them, for the leading steps to such a discovery  could not be
kept a secret.  The winter following Dr. MacKenzie began to teach midwifery
in the Borough of Southwark.
  a " As the ovum was so extremely small as to admit of dispute whether it was
one or not, I carried it immediately to Kew, to Mr. Bauer, who, after examining
it, said it looked like the egg of an insect."—Phil. Trans., p. 255.
  Mr. Clift who laid  open the uterus in question, and patiently scrutinized the
whole of its cavity without perceiving any trace of an ovum, has always been of
opinion that the one afterwards detected by Home was dropped from one of the
numerous flesh-flies which were buzzing about at the time of the examination. 
94
HUNTER ON THE ANIMAL CECONOMY.
 to what seemed to be an irregular  mass of injected matter.  The
 appearance being new he proceeded no further, and greatly obliged
 me, by  desiring my  attendance to examine  parts, in  which the
 appearances were so uncommon.   The examination was made in
 his  presence,  and in  the presence of several other  gentlemen,
 whose names I have how forgotten ; but I have reason  to believe
 that some are settled in this country, who I hope will have an oppor-
 tunity of perusing this publication.*
   I first raised, with great  care, a part of the uterus from the irre-
 gular mass, and in doing this observed regular pieces of wax passing
 obliquely between it  and the uterus, which broke  off, leaving part
 attached to that mass;  and on attentively examining the portions
 towards the uterus, they plainly appeared to be a continuation of
 the veins passing from it to this  substance, which proved to be pla-
 centa.
   I likewise observed other vessels,  about the size of a crow-quill,
 passing in the same manner,  although not so obliquely ; these also
 broke upon separating the placenta and uterus, leaving a small portion
 on the surface of the placenta ; and on examination they were disco-
 vered to be continuations of the arteries of the uterus.  My next step was
 to trace these vessels into the substance of what appeared placenta,
 which was first attempted in a vein; but that soon  lost the regular-
 ity of a vessel,  by terminating at once upon the surface of the pla-
 centa in a very fine spongy substance, the interstices of which were
 filled with the yellow injected matter.   This termination  being new,
 I repeated the same kind of examination on other  veins, which al-
 ways led me to the same terminations, never entering the substance
of the placenta in the form  of a  vessel.  I then examined the arte-
ries, tracing them in the same manner towards the placenta, and
found that, having made a twist, or close spiral turn upon themselves,
they were lost  on its  surface.  On a  more attentive view, I per-
ceived that they terminated in the same way as the veins ; for op-
posite to the mouth of the artery the spongy substance of the pla-
centa was readily distinguished with the red injection intermixed.
  Upon  cutting into the placenta I discovered, in many places of its

  * If I should be so fortunate as to have this publication fall  into  any of those
 gentlemen s hands, I hope they will favour me with their opinion of my state of
the facts, which led to the discovery.
  It may be suspected  by some (but none I hope to whom I have the pleasure of
being known,) that lam not doing Dr.  MacKenzie  justice, and am  perhaps sup-
pressing some part of that share  of the discovery to which he is entitled.  This
idea (if ever ,t should arise), I may probably not be able to remove; but I hope
t^JrZ tlT? that * "P^ haVe Siven rise to it;  believing, if I had been
bo. Hicl ned, that I might have  suppressed Dr. MacKenzie's name altogether
without ever running the hazard of being detected.  I was indeed so tenacious of
my claim to the discovery, that I  wrote this account in Dr. MacKenzie's lifetime
with a design to publish it; and often communicated my intentions to Dr Geome
Fordyce, who 1 knew was very intimate with the Doctor, in consequence of both
teaching in the same place, and making many experiments together; therefore he
is a k.nd of collateral  witness, that what  I now publish is  the same  account
which I gave in Dr. MacKenzie's lifetime. 
ON THE  STRUCTURE OF THE PLACENTA.          95
substance, yellow injection, in others red, and in many others these
two colours mixed.   The substance of the placenta, now filled with
injection, had nothing of the vascular appearance, nor that of extra-
vasation, but had a regularity in its form  which showed it to be
naturally of a cellular structure, fitted to be a reservoir for blood.
  I perceived, likewise, that the red injection  of the arteries  (which
had been first injected), had passed out of the substance of the pla-
centa into some of the veins leading from the  placenta to the  uterus,
mixing itself with the yellow injection ; and that the spongy chorion,
called the decidua by Dr.  Hunter, was  very vascular, its  vessels
going to and from the uterus, being filled with the different coloured
injections.
  After having considered these appearances, it was not difficult
for me to determine the real structure of the placenta and course of
the blood in these parts:  but  the  company, prejudiced in favour of
former theories, combated  my opinion ;  and it was even disputed
whether or not these curling arteries could carry red blood.   After
having dissected the uterus, with the placenta and membranes, and
made the whole into preparations, tending to show the above facts,
I returned home in the evening, and communicating what I had dis-
covered to my brother, Dr. Hunter, who at  first treated it and me
with good-humoured  raillery; but on going  with me to Dr. Mac-
Kenzie's he was soon convinced of the fact.  Some of the parts
were given  to him,  which he afterwards showed at his lectures, and
probably they still remain in  his collection.
   Soon after this time Dr. Hunter and I procured several placentse,
to discover if after delivery, the termination of the veins and  the
curling arteries could be observed ; they were discernible  almost in
every one ;  and by pushing a pipe into the placenta we could fill not
only its whole substance, but also the vessels  on that surface which
was attached to the uterus, with injection.
   The facts being now ascertained and universally acknowledged,
I consider myself as  having  a just claim  to the discovery of the
structure of the placenta, and its communication with the uterus, to-
gether with the use arising from such structure and communication,
and of having first demonstrated the vascularity of the spongy cho-
rion.
   It is not necessary at  present to enter into  the various opinions
which have been formed on this subject; because,  whatever they
were, they  could not be  just, the structure of  the parts not being
known : neither shall I  endeavour to give a complete description
of all the parts immediately connected with uterine  gestation, but
content myself with describing the structure of the placenta, as far
as it  has any  relation to  the uterus and child; and with explaining
the connexion between the two ; leaving the reader to examine what
has been said upon this subject by others, especially by Dr. Hunter,
in that very accurate  and  elaborate work which he has published
on the Gravid Uterus, in which he has minutely described and ac-
curately delineated the parts, without  mentioning the mode of dis-
covery. 
96
HUNTER ON THE ANIMAL CECONOMY.
  The necessary connexion subsisting  in all  animals between the
mother and foetus, for the nourishment of the latter, as far as I know,
takes place  in  two  ways.  In some it is continued, and subsists
through the whole term of gestation ; in others the union is soon dis-
solved ; but an  apparatus is provided, which at once furnishes what
is sufficient for  the support of  the animal till it comes forth.
  The first of these  are  the viviparous, the  second the oviparous
animals, both of which admit of great variety in the mode by which
the same effect is produced.*  In the first division is included the
human species, which alone will engage our present attention.  But
before I describe this connexion, it  may be  necessary that the rea-
der should understand my idea of generation: I shall therefore re-
fer  him to what I have said upon that subject in my  account of the
free-martin.f
  In the human species, the anatomical  structure of the mother and
embryo, relative to foetation, being well known, it will only be neces-
sary fully to  describe the nature  of the connexion between them,
which is formed by the intermediate substance called placenta.  For
this purpose we must first consider the placenta as a common part;
next, the uterus as belonging to the  mother, yet having an immediate
connexion with the placenta, from which the nourishment of the foetus
is to be derived, which will lead us lastly to a consideration of those
peculiarities of  structure by means of which the foetus is to receive its
nourishment, and which  likewise constitutes its immediate commu-
nication with the placenta.  It is the structure of this intermediate
substance, and  its connexion with  the child  and the  uterus of the
mother, which  have hitherto been  so little understood, and without
any accurate knowledge of  which it was impossible any just idea
could be formed of its functions.
  The placenta is a mass lying nearly  in contact with the uterus ;
indeed it may in some degree be  said  to be in  continuity with a
part of its internal surface.  On the side applied  to the uterus  the
placenta is lobulated, having deep irregular fissures.  It is probably,
from  this structure of the placenta,  that the uterus has an intestine
motion while in the  time of uterine gestation,  not an expulsive one;
which those lobes of the placenta allow of; but all these lobes are united
into one uniform surface on that surface next  to the child, where its
umbilical vessels ramify.  When we cut into the placenta its whole sub-
stance appears  to be little else than a network,or spongy mass, through
which the blood-vessels of the foetus ramify, and indeed seems to be
principally formed by the ramifications of those vessels; it exhibits
hardly any appearance of connecting membrane; but we cannot rea-
dily suppose it  to be without such a membrane, as there is so much

  * It may be remarked here, that the oviparous admit of being distinguished
into two classes, one where the egg is hatched in the belly, as in the viper, which
has been commonly called viviparous; the others, where the eggs have been first
laid and then hatched, which is the class commonly called oviparous, such as all
the bird tribe:  and many others,  as snakes, lizards, &c.
  f See page 70. 
ON THE STRUCTURE OF THE PLACENTA.         97
regularity in its texture.  The cells, or interstices of each lobe, com-
municate with one another,  even much more freely than those of
the cellular membrane in any other part of the body ; so that what-
ever fluid will pass in at one part, readily diffuses itself through the
whole mass of lobe; and all  the cells of each lobe have a commu-
nication at the common base.
   This structure of the placenta, and its reciprocal communication
with the two bodies with which it  is immediately connected, form
the union  between  the mother  and foetus  for the support of the
latter.   Prior to the time I have mentioned above, anatomists seem
to have been wholly unacquainted with the true structure of placenta.
By notes taken from Dr. Hunter's lectures, in the winter 1755-6, it
appears that he expressed himself in the following manner.*   " The
substance  of the placenta is  a fleshy mass, which seems to be formed
entirely of the vessels of the  umbilical rope."  In another part, men-
tioning the appearances when injected, he says: " and upon a slight
putrefaction coming on,  you will  find the  whole appearing like a
mass of vessels:" then says," there is always a white  uninjected
substance  between the vessels ;  but whether lymphatics or what I
cannot tell."   This uninjected substance, mentioned by Dr. Hunter,
is what forms the cellular structure.
   The placenta seems to be principally composed of the ramifica-
tions of the vessels of the embryo,  and may have been originally
formed in consequence of those next to the  uterus laying hold by a
species of animal attraction of the coagulable lymph which lines
the uterus.  It  might take place in a manner resembling what hap-
pens when the root of a plant spreads on the surface of moist bodies,
with this difference, that in the present instance the vessels form the
substance through which they ramify, as in the case of granulations.
   At the time,  or perhaps before, the female seed enters the uterus,
 coagulable lymph, from the blood of the mother, is thrown out every-
 where on  its inner surface, either from the stimulus of impregnation
 taking place in the ovarium, or in consequence of the seed being ex-
 pelled  from it.   But I think the  first the most probable supposition;
 for we find in extra-uterine  cases  that the decidua is formed, in the
 uterus, although the ovum never enters it, which  is a proof that it is
 produced  by the stimulus of impregnation in the  ovarium, and that
 it is prior to the entrance of  the ovum into the uterus.   When it has
 entered the uterus it  attaches itself to that coagulable  lymph, by
 which, being covered and immediately surrounded,! there is formed
 a soft  pulpy membrane, the decidua, which I believe is peculiar to

   * These quotations were taken from  Mr. Galhie's MS. of Dr. Hunter's lectures,
 who is  one of the gentlemen that favoured Dr. Hunter, upon a former occasion,
 with the use of his notes.  See Dr. Hunter's Commentaries.
   f This is somewhat similar to  another operation in the animal ceconomy. If an
 extraneous living part is introduced  into any cavity it will be immediately in-
 closed with coagulable lymph.  Thus we find worms  inclosed, and hydatids,
 that have been detached, afterwards inclosed ; but in those cases this is a con-
 sequence of the pressure of the extraneous body, whereas  in the uterus it is pre-
 paratory. 
98
HUNTER ON THE ANIMAL CECONOMY.
the human species and to monkeys, I never having found it m  any-
other animal.  That part which covers  the  seed or foetus, where
it is not immediately attached to the  uterus, and  likewise  forms a
membrane,  was discovered  by Dr. Hunter, and is  by him called
decidua reflexa.*   The whole of this coagulable lymph continues
to be a living part for the time; the  vessels  of the  uterus ramify
upon  it;  and where the  vessels of  the fcetus form the placenta
there the  vessels of the uterus, after passing through the decidua,
open into  the cellular substance of the placenta, as before described.
As  this  membrane lines the uterus and covers the  seed,  it  is
stretched  out, and  becomes  thinner and thinner, as  the uterus  is
distended  by the foetus  growing larger,  especially that part of it,
called decidua reflexa, which covers the  foetus; as there it cannot
possibly acquire any new  matter, except we could suppose  that
the foetus  assisted in the formation of it.   This membrane  is most
distinct where  it  covers the chorion; for  where  it  covers  the
placenta it is blended with  coagula in the great veins that pass
obliquely  through  it, more  especially all round  the edge, where
innumerable large  veins come out; but  the  chorion and  decidua
can be easily distinguished  from  one another, the  decidua being
less elastic.
  From the description now given, I  think we are justified  in sup-
posing the placenta to  be formed  entirely by the fcetus, which  is
further confirmed by extra-uterine  cases, and by the formation of
the membrane in the egg, there being no living organic part to fur-
nish them; and the decidua we must suppose  to be a production of
the mother: of both which the circumstance of the decidua passing
between the placenta and uterus may be considered as an addi-
tional proof.  For if the vessels of the foetus branched into a part
of the decidua, we might conceive the whole placenta to be formed
from that  exudation; the portion of it, where the vessels had rami-
fied like the roots of a plant, becoming thicker than the  rest,  and
forming  the placenta.   If  that  were the case, this  membrana
decidua, when traced from the parts distinct, and at a distance from
the placenta, should be plainly seen passing into its  substance all
round at the edges, as a continuation of  it.   But the fact  is quite
otherwise; for the  decidua  can be distinctly traced between the
placenta and uterus, hardly ever  passing  between  the lobuli, the
vessels of the foetus never entering into it, and of course  none of
them ever coming in absolute contact with the uterus.  But what
may be considered as still a stronger proof that the  decidua is  fur-
nished by the uterus is, that in cases  of  extra-uterine  conception,
where the foetus is wholly in the ovarium or Fallopian  tube, we
find the uterus lined with the decidua, having  taken  on  the uterine

  * The placenta is certainly a foetal part, and is formed on the  inside of the
spongy chorion, or decidua.  How far the decidua  reflexa  is a uterine part I do
not yet know ; if it is, then the ovum must be placed in a doubling of the coaeu-
lum, which forms the decidua ; but if the ovum  is attached to the inside of the
decidua, then the decidua reflexa is belonging to the fcetus. 
ON THE STRUCTURE  OF THE PLACENTA.         99
action;  but no placenta, that being formed by the fcetus, and there-
fore in the part which contained it.
  The  vessels of the foetus adhering, by the  intervention of the
decidua, to a certain portion of the uterus when both are yet small, as
the uterus increases in every part of its surface during the time of
uterine gestation, we must suppose that this surface of  adhesion
increases also; and that by the elongation of those vessels  of the
fcetus in every direction this substance should likewise be increased
in every  direction.  This is in  some  degree the case, yet the
placenta does not occupy so much of the enlarged  surface  of the
uterus as one  at first would expect.
  The vessels of the  uterus in  the  time of the gestation are  in-
creased in size nearly in a proportion equal  to the increased cir-
cumference of the uterus, and consequently in  a proportion much
greater  than the real increase of its substance.  But when we reflect
that the uterus ought not to be considered as hollow, but as a body
nearly solid, on account of its contents, which derive  support from
this source, and  that a much greater quantity of blood must neces-
sarily pass than  what is required for the subport of the viscus itself,
we cannot be at a loss to account for the greatly increased size of
its vessels.
  The arteries which are not immediately employed in  conveying
nourishment to the uterus go on towards the placenta, and, pro-
ceeding obliquely between it and the uterus, pass through the decidua
without ramifying; just before  they  enter the  placenta,  after
making two or three close spiral turns upon themselves, they open
at once into its  spongy substance without any diminution of size,
and  without  passing beyond  the surface,  as above  described.
The intention of these spiral  turns  would appear to  be that of
diminishing the force of  the  circulation in  the vessels as they ap-
proach  the spongy substance of the placenta, and is a mechanism
calculated to lessen the quick motion  of the blood in a part where
a quick motion was not  required.  These curling  arteries at this
temination are in general about half the size of a crow's quill, and
sometimes larger.
  The veins of  the uterus appropriated to bring back the blood
from the placenta commence from this spongy substance by such
wide beginnings  as are  more than equal to the size  of the veins
themselves.  These veins pass obliquely through the decidua to the
uterus, enters its substance obliquely, and immediately communicate
with the proper veins  of the uterus.  The area of these veins bears
no proportion to their circumference, the veins being very much
flattened.
  This  structure of parts points out at once the nature of the blood's
motion  in the placenta; but as this is a  fact but lately ascertained,
a just idea may perhaps be conveyed by saying that it is similar, as
far as we yet know, to the blood's motion through  the  cavernous
substance of the penis.
  The blood, detached from the common circulation of the mother, 
100
HUNTER ON THE ANIMAL CECONOMY.
moves  through the placenta of the foetus;  and  is  then  returned
back into the course of the circulation of the mother, to pass on to
the heart.                                                    ,,   ,
   This structure of the placenta, and its  communication with the
uterus,  leads us a step  further in our knowledge  of  the  connexion
between the mother and the foetus.   The blood  of the mother must
pass freely into the substance of the placenta, and the placenta most
probably will be constantly filled ;  the turgidity of which will assist
to squeeze the  blood into the  mouths of  the veins  of the  uterus,
that it may  again pass into the common circulation of the mother;
and as  the interstices of the  placenta are of much  greater extent
than the arteries which convey  the blood, the motion of the blood
in that  part  must be so much diminished as almost to approach to
stagnation.  So far and no further does  the  mother  appear to be
concerned in this connexion.
   The  foetus has a communication with  the placenta of  another
kind.   The  arteries from  the  foetus pass  out  to a  considerable
length,  under the name of the  umbilical  arteries, and when they
arrive at the placenta ramify upon its surface, sending into its sub-
stance  branches which pass through  it, and divide into smaller and
smaller, till  at last they terminate  in  veins;  these, uniting, become
larger and larger, and  end in one, which at last communicates with
the proper circulation of the  foetus.
   This course  of vessels, and the blood's motion in them, is similar
to the course of the vessels and the  motion of the  blood in  other
parts of the  body.*

  * [It is well known that the accuracy of this description has been disputed by
several continental anatomists, and has especially been called  in question in this
country  by Dr. Robert Lee, F.R.S., who, with a zeal becoming a  sincere lover
of truth, deemed it his duty to submit  to the scientific world the results of a series
of investigations,  which he considered to  be irreconcileablein some respects with
the Hunterian descriptions.  During the period in which Dr. Lee was examining,
at the College of  Surgeons, the Hunterian Preparations,  illustrative of the struc-
ture and connexions of the placenta, his  observations on the obscurity produced
by apparently extravasated injection,  led  me to think of some less objectionable
mode of demonstrating the vascular communication between the uterus  and
placenta, if it existed ; or  of proving, more satisfactorily than the appearance
pointed  out by him in the Hunterian preparations seemed  to do, that there was
no such  communication.
   This I proposed to do by dissecting the  parts  under water before disturbing
them, either by throwing forcibly foreign matter into the vessels, or by separating
the placenta from the uterus, to observe  the appearances  presented  by the op-
posed surfaces; a proceeding which,  if done in the air, is liable to the objection
of the possibility  of having torn the vessels which were passing across, and the
coats of which are acknowledged  to be extremely delicate.
   For this purpose I was furnished by Dr. Lee with sections of an uninjected and
naturally connected uterus and placenta,  at the sixth month of uterine gestation,
which I fixed under water in an apparatus used for dissecting mollusca, and com-
 menced the dissection from the outside, removing successively, and with great care,
the layers of  fibres, and tracing the veins  as they passed deeper and deeper in
the substance of the uterus in their course to the deciduous membrane ;  in which
 situation, as the thinnest pellicle of membrane is rendered distinct by beincr sup-
 ported in the  ambient fluid, I naturally expected to see the coats of the "veins 
ON THE STRUCTURE OF THE PLACENTA.          101
    In addition to what I have said about the connexion between the
 mother and child in natural cases, it  is  necessary to  observe, that

 continued into the deciduous membrane and  placenta, and to be able to preserve
 the appearance in  a preparation,  if it actually existed in nature.  Every vein,
 however, when traced to the inner surface of the uterus, appeared to terminate in
 an open mouth on that aspect; the peripheral portion of the coat of the vein, ox
 that next the uterus, ending in a well-defined and  smooth semicircular margin,
 the central part adhering to, and being continuous  with, the decidua.
   In the course of this  dissection I observed that where  the veins of different
 planes communicated with each other, in the substance of the walls of the uterus,
 the central portion of the parietes of the superficial vein invariably projected in a
 semilunar form into the deeper-seated  one ; and where  (as  was frequently the
 case, and especially at the point of termination on the  inner  surface), two, or
 even three, of these wide venous channels communicated with a deeper sinus at
 the same point, the semilunar edges decussated each other so  as to allow only
 a very small part of the deep-seated vein to  be  seen.   It need  scarcely  be ob-
 served how admirably this structure is adapted to insure the arrest of the current
 of blood through these passages, upon the contraction  of the muscular fibres
 with which they are everywhere immediately surrounded.
   On another portion of the same uterus and  placenta, I commenced the exami-
 nation under water by turning off the placenta and deciduous membrane from the
 inner surface of the  uterus.   In this way the small tortuous uterine arteries  which
 enter the deciduous membrane were readily  distinguishable, though  not filled
 with injected matter;  and, as it was an object to avoid unnecessary force  in the
 process of separation, they were cut through, though  they are easily  torn from
 the decidua.   But with respect to the veins, they invariably presented  the same
 appearances  as were noticed in the first dissection, terminating in open semicir-
 cular orifices, which are closed by the apposition of the deciduous membrane
 and placenta.  This membrane is, however, thinner opposite these orifices than
 elsewhere, and  in tome places appeared to be  wanting, or, adhering  to the vein,
 was torn up with it; but in these cases the minute vessels of the placenta only
 appeared, and  never any indication of a vascular trunk or  cell commensurate
 with the size of the vein whose terminal aperture had been lifted up from the part.
  The above results of  my examination of the impregnated uterus, which  had
 been furnished to me by Dr. Lee, I communicated, as I had promised to  do, to
 that gentleman.  They appeared decisive of the fact that the veins of the uterus
 were not continued as such across the decidua, to terminate in visible cells in the
 substance of the placenta;  but whether the terminal orfices of the veins derived
 no returning blood from the interstices of the decidual laminae, was by no means
 certain.  For my own part, having satisfied myself of the passage of the tortuous
 uterine  arteries into the  decidua, I undoubtedly considered  the  uterine venous
sinuses as the most probable and natural channels by which the blood conveyed
 from the uterus by the tortuous arteries would return again to that body ;  although
I was unable to determine from this dissection how the blood was returned into
the open mouths of the veins.
  It must be admitted, that an impregnated uterus  at the fifth month, where the
vessels, which are very small, had been contracted by the spirit  in which the
parts had been preserved, was not a very favourable subject for  so delicate an
investigation ; and I accordingly felt extremely desirous of repeating the dissec-
tions on gravid uteri  at a  more advanced period.  These opportunities do not, as
is well known, frequently occur: about a year  after I was, however, favoured by
Dr. Lee with  a large portion of a gravid uterus of a woman who  died about the
ninth month of gestation,  in which the uterine veins had been gently filled with red
size injection. This preparation was submitted  to the same mode of dissection. In
tracing those veins which passed to the inner surface of  the  uterus, near the
middle of the placenta, the injection was seen to be continued  from  them into
oblique, wide, but shallow channels, leading through the external decidua into
the  placental decidua, and  had thence  been diffused through the fine spongy
                                   10* 
102            HUNTER ON  THE ANIMAL CECONOMY.
though the uterus is appropriated for  the support of  the fcetus, as
best fitted for that purpose, yet it is not essential to its growth; as
any other part  in which the child may be  situated, is capable ot
receiving  the same provisionary  stimulus  for supplying  it with
nourishment as  the nterus ; and this, I believe, is peculiar to genera-
tion.   This prompts me to make the  following  observations upon
the different situations of the foetus in  extra-uterine  cases, which
are  extraordinary, happen seldom, and  when  they  do  occur  are
often attended with so many  hindrances to critical investigation, as
hardly to allow of thorough or satisfactory information.
   Such cases are readily distinguished  from  natural ones by the
uterus being found entire and empty ; and they  may be divided into
three different kinds, according to the situation of the fcetus in the
ovarium, Fallopian tube, or in  the  cavity of the abdomen.
   From a  want of the appearances which usually attend  the natural
process, the investigation of  extra-uterine  cases is attended  with
considerable difficulty.   For where uncommon  actions have taken
place, as well as in cases of  disease, the natural texture of the parts

cellular tissue which  everywhere  surrounds and supports the fcetal capillaries.
On comparing these  appearances  with my first dissection, I perceived that the
uterine vein, opposite the mouth of which I had supposed the decidua to be want-
ing, and whose orifice was in contact with the capillaries of the placenta, was
in reality one of the oblique decidual  canals, returning the blood from the cellular
substance of the placenta into the uterine vein, its continuity with which had
been preserved.
  The continuation of the uterine veins into decidual canals was much more dis-
tinct in those which terminated near the circumference of the placenta ; and here
the irregular portions of injection,  which filled the canals as far as the surface of
the placenta, were evidently circumscribed, by  distinct parietes,  and not the
result of confused extravasation : the injection  from the decidual canals had
passed into the large interlobular spaces, or maternal sinuses of the  placenta, and
thence had become diffused,  generally for the extent of an inch, into the spongy
or cellular texture of the placenta.
   The uterine arteries in this case had not been injected, but were easily trace-
able passing through the external and placental decidua, as far  as  the internal
surface of the latter, and apparently  opening or being lost on the spongy surface
of the placenta.
   With reference  to  preparations of vascular and cellular structures like the pla-
centa, it is  not easy  to enforce conviction from the appearances they present, in
consequence of the  difficulty of distinguishing between natural and accidental
extravasation.
   Having,  however, carefully compared the Hunterian preparations with the
results  of my own examinations  of the  gravid uterus at the full period, 1 now
believe they all fully bear out Mr.  Hunter's general view, viz., that the maternal
blood is diffused,  by means of the  tortuous arteries, into the spongy cellular sub-
stance of the placenta, where it bathes the  capillaries  of the foetal circulation,
and is returned by the oblique decidual adventitious sinuses and channels into
the orifices of the  uterine veins. Thus the placental intercommunication between
the fcetus and mother, in the human subject and Quadrumana, is carried on by
the contact of the foetal capillaries with maternal extravasated blood • while in
  a [In the last two examples the placenta may be said to be diffused over
the whole surface of the chorion.] 
ON THE PLACENTA OF THE  MONKEY.
103
is very much altered, and appears to be lost, not only by the parts
themselves being enlarged, but from having  a great deal of new
matter superadded  to them, by which  they lose their natural  dis-
tinctness, and become less fitted for examination than those which
only have a relation  to  them, and which preserve their natural
actions peculiar to that state.
  From  these difficulties, and  a want  of  accuracy  in those who
made the examination, it is not  at  present clear,  with respect to
many of the extra-uterine  cases upon  record, whether they were
ovarian cases, Fallopian tube  cases, or abdominal  cases ; when, if
they had been acquainted with the  principle  in which they differ,
nothing could have been more easy than to distinguish them.   It is
not difficult, perhaps, at the very first view, to distinguish an abdo-
minal case from either of the two first: for if the ovaria and Fallo-
pian tube are entire, natural,  and can  be well distinguished to be
as those parts are when the  circumstances  are natural, then we
may be sure it is an abdominal case.   Appearances, however, may
not in all cases be distinct;  but the parts may adhere, or be other-
wise  rendered so obscure, that an abdominal case might be con-
founded  with either of the two first; therefore it is essential to have
a characteristic difference established  between the  two first, and
the third.
   The invariable difference between the two first, and the abdominal
cases, will be in the vessels by which  the  child is nourished : for
the arteries and veins belonging to the  part in  which the child  is
contained must be enlarged ;  which, being the increase of a natural
part, will be readily ascertained,  and the  nature of the case as
readily determined.  We may lay it down as a principle, that when
the spermatic artery and  veins of either side are enlarged in an
extra-uterine case, that the foetus is in the ovarium or  Fallopian
tube; since there are no other blood-vessels  which supply these
parts; and  if any other system of  vessels, as  the  mesenteric, are
increased in size, while the spermatic  are in  a natural state, we
 may with equal certainty conclude the foetus to be contained in the
general  cavity of the belly.  As this becomes  the great criterion,
 and as the situation and time  will not always allow very nice in-
 vestigation on the spot, where the  person  employed has an oppor-
 tunity of taking away the parts concerned, I would advise his taking
 along with them the aorta and vena cava, cut through above the
 origins of the spermatic vessels.
  8. OBSERVATIONS ON THE  PLACENTA  OF THE
                         MONKEY.
  Monkeys always copulate backwards:  this is performed some-
times when the female is standing on all-fours;  and at other times
the male brings her between his thighs when he is sitting, holding
her with his fore paws. 
104          HUNTER ON THE ANIMAL CECONOMY.
   The female has her regular periods for the male, but she has
 commonly too much complaisance ever to refuse him.  They carry
 this still further, for they receive the male when with young, even
 when pretty far gone : at least this was the case with oneot which
 I am going to give an account.
   A female monkey, belonging to Mr. Endersbay, in the summer
 1782, had  frequently taken the  male.   The keeper  observed  that
 after the 21st of June she became less  lively than usual, although
 it  was not suspected that she had conceived ;  but  some time after
 appearing to be bigger in the belly, it created  a  suspicion of her
 being with young.  Great attention was paid to her, and great care
 was taken  of her.  She went on gradually increasing in  size;  and
 at last something  was observed to move in her  belly at particular
 times, and  the motion could even be felt through the  abdominal
 muscles. She became indolent, and did not like to leap or perform her
 usual feats  of activity.   Towards the latter part of  the  time they
 perceived the breast and nipple to have become rather fuller, and
 that a kind of water could be squeezed out at  the nipple.  Some
 time before she brought forth, she became red  about  the hips and
 posteriors,  which  redness extended to the  inside  of the thighs.   It
 being now certain that she was with  young, I desired that she
 might be particularly attended  to when there were  signs  of ap-
 proaching delivery, both on her own account and that of the young
 one, and requested the afterbirth might be carefully preserved, as
 that part would assist to ascertain  the  mode of uterine  gestation.
 These directions were  attentively followed; and when in labour it
 was observed that she had regular pains, that when the young one
 was in part come into the world, she assisted herself with her  fore
paws, and that it  came with the  hind parts first.  This  happened
 on the 15th of December 1782, in all about six  months after con-
 ception ;  and when she brought forth  her young one it showed
 signs of life, but died immediately, owing probably to the  unfavour-
 able mode of its being brought into the world.  When delivered she
 took the young one  up, and although  it  was dead clasped it to
 her breast.
   The afterbirth  was preserved entire, and was  perfectly  fit for
 examination.   It  consisted  of placenta, with the membranes  and
 navel-string, which  all very much  resembled  the corresponding
 parts' in  the human subject,  as will now be described.
   The placenta had the appearance of  being  divided  into  two
 oblong bodies, united by their edges, each terminating in an  obtuse
 point at the other end, which were of course at some little distance
 from one another.
   It is probable that  these  two prints  were placed towards the
 openings of the Fallopian tubes, where the uterus  assumes  a form
 resembling two obtuse horns.
   The two lobes above-mentioned were made up of  smaller ones
 united closely at their edges, which were  more  apparent and dis-
 tinct at some  parts than at others.   Some of these  lobes were
 divided  by  fissures which seem to be derived from one centre, while 
         OF A WOMAN WHO HAD THE SMALL-POX, ETC.    105

there were others near the edges passing  in a  different direction,
in which fissures are placed veins or sinuses that receive the blood
laterally from the lobes.  The substance of the placenta seems to
be cellular, as in the human  subject: this structure allows a com-
munication to be kept  up between different parts of each lobe, and
the sinuses allowing of a communication between the different lobes
of which the placenta  is  composed, the blood passes into the fissures
before  it enters  the veins;  in which respect  it  differs from  the
human placenta.
  The arteries from the uterus, on the surface of the  placenta,
were visible, but too small to be  injected: I cannot  therefore  say
how they terminated in the placenta.
  The principal veins  arose  in general from the fissures beginning
from the surface, as in the human placenta ;  but besides these, there
were other  small ones; all which, we may suppose, pass through
the decidua and enter  the substance of the uterus, most probably in
the same way as in the human subject.
  The membranes are the amnios, the chorion, and the membrana
decidua.  These  appear to  be much the same as in the human,
except that the decidua is considerably thicker, especially where it
passes  between the uterus and the placenta.
  The navel-string  in the monkey is not proportionally so long as
in the human, and is very much and very regularly twisted.
  There is no urachus, and  of course no allantois; not even  the
small ligament that appears to be a drawing-in of the bladder at its
attachment to the navel, the  bladder here being rounded.
9.  ACCOUNT  OF A  WOMAN WHO  HAD THE  SMALL-
    POX DURING PREGNANCY, AND WHO SEEMED TO
    HAVE  COMMUNICATED THE  SAME DISEASE TO
    THE FCETUS.   BY JOHN HUNTER, ESQ., F.R.S.*
                      Read January 17, 1780.

                     Mr. Grant's Account.
  On the 5th of December, 1776, Mrs. Ford  had been seized with
shivering and the other common symptoms of fever, to which were
added great difficulty of breathing and a very hard cough.  Mr.
Grant saw her on the 7th, and he took from her eight ounces of
blood, and gave her a composition of the saline mixture with sper-
maceti and magnesia every six hours.
  This had  operated  by the 8th two or three times very gently,
when  most  of the complaints were relieved ; but the cough still
shaking her  violently,  bleeding seemed necessary to be repeated,
more  particularly as  she  looked upon herself to be in the sixth

  * [Originally published in the Philosophical Transactions, vol. lxx., 1780.] 
106
HUNTER ON THE ANIMAL CECONOMY.
month of her pregnancy.  The medicine was continued without the
i masrnesia.
  In the evening (viz..  the  8th) the small-pox appeared, wmcn
proved of a mild kind, and moderate in quantity.   Its progress was
rather  slower than  might have been expected;  but the woman
passed through the-disease in great spirits, sitting up the greatest
part of the day during the whole time, and taking only a paregoric
at night, and, as occasion required, a  little  magnesia;  thus  the
symptoms were mitigated, and the cough at last became very little
troublesome.
  On the 25th she complained of a pain in her side.  Eight ounces
of blood were taken away.-  The next day she was quite free from
pain, and thought herself as well  on  the 27th as her particular
situation  would admit of; after which she was not visited by Mr.
Grant till the 31st, when she was in labour.

             Mr. Wastall's Letter on the same subject.

  December  30, 1776,  I  was sent  for to  Mrs. Ford,  a healthy
woman, about twenty-two years of age, who was pregnant with
her first  child.  She  had come  out of the  country about three
months before.  Soon after her arrival in town she was seized with
the  small-pox, and had been under the care of Messrs. Hawkins
and Grant,  who  have  favoured  me  with the particulars here
annexed.
  I called upon her in  the  afternoon, she complained of violent
griping pains  in her bowels, darting down  to the pubes.  On ex-
amining, I found the os tineas a little dilated, with other symptoms
of approaching labour.   I sent her an anodyne spermaceti emulsion,
and desired  to be called if  her pains  increased.  I was sent  for.
The labour advanced very slowly ; her  pains were long and severe:
she  was delivered of a dead child with some difficulty.
  Observing an eruption all over the body of the child, and several
of the pustules filled with  matter, I examined  them  more particu-
larly;  and recollecting that Dr. Leake, in his Introductory Lecture
to the Practice of Midwifery, had observed, that it might be neces-
sary to inquire whether those adults who are said totally  to escape
the  small-pox have not been previously affected  with it in the womb,
I sent a note  to Dr.  Leake, and likewise to Dr. Hunter, in hopes of
ascertaining a fact hitherto  much doubted.  Dr. Leake  came the
same evening, and  saw the child.  Dr. Hunter  came  afterwards,
with Mr. Cruickshank, and examined it; also Mr. John Hunter  and
Mr. Falconer; who all concurred with me, that the eruption on the
child was the small-pox.   Dr. Hunter thought the eruption so  like
the  small-pox that he could hardly doubt; but said, that in all other
cases  of the same kind that he had met with, the child in  utero  had
escaped the contagion. 
OF A WOMAN WHO  HAD THE SMALL-POX, ETC.     107
                    From Mr. Grant's Notes.

  The eruption appeared on Mrs. Ford in the evening of the 8th of
December, and  she was delivered the 31st, that is, twenty-three
days after the appearance of the eruptions.

                 Reflections by Mr. John Hunter.

  The singularity of the  above case, with all its circumstances, has
inclined me to consider it with some attention.
  There can be no doubt that the mother had the small-pox, and
that the eruption began  to  appear on  the 8th of December; also,
that it went through its  regular stages, and  that on the 31st, viz.
twenty-three days after  the first  appearance of the eruption the
woman was delivered of the child, who  is  the subject  of this
paper.
  Secondly, The distance of time when she had the small-pox before
delivery, joined  with the stage  of the disease  in the child  when
born, which probably was about the  sixth or  seventh  day of the
eruption, viz., about fifteen or sixteen days after the beginning of the
eruption on the mother, perfectly agrees with the possibility of the
infection's  being caught from the mother.
  Thirdly, The external  appearance of the pustules in the child was
perfectly that of the  small-pox, as must have  appeared from the
relation given in Mr. Wastall's  letter.   Most of the pustules  were
distinct, but some wrere blended  or united at their base.   The face
had the greatest number, and  these were  in general the most in-
distinct.   They  were  somewhat  flattened,  with a  dent  in the
middle.*
  So far were the leading circumstances and external appearances
in favour of their being the variolous eruption; but although  these
leading circumstances and external appearances were incontro-
vertible, yet they were  not an  absolute  proof of this being the
genuine small-pox; therefore  I  must be allowed to consider this
subject a little further, and see  how far all the circumstances cor-
respond or are similar to the true small-pox.   In the small-pox we
have  a previous fever, in place  of which, in the present case, we
have  no information but that of  the mother's having had the small-
pox within such a limited time as may favour the possibility of in-
fection in the womb ; yet we may presume that the child must have
had considerable fever preceding such an eruption, of whatsoever
kind  it was.
  In the small-pox the eruption goes through pretty regular stages  in
its progress and declension, which  circumstances we know nothing
of in the present case; but even this fever, the eruptions, and  their

  * I  endeavoured to take  some matter upon the point of two lancets; but not
having an opportunity of making an experiment myself, I gave them to two gen-
tlemen, who, I imagine, were afraid of inoculating with them. 
108          HUNTER ON THE ANIMAL GECONOMY.
progress, are not absolutely proofs that the disorder is the small-pox
when it is caught in the common and natural way;  and in proof ot
this assertion, it may be observed, that practitioners every now and
then are mistaken.                                            ?
  It maybe asked, What is the true characteristic of the small-pox .
That by which  it differs from all other eruptions that  we are  ac-
quainted with?   The most certain character of the small-pox that
I know  is, the formation of a slough, or a part becoming dead by
the variolous  inflammation;  a circumstance which hitherto, 1 be-
lieve, has not been taken notice of.
  This was very evident in the arms of those who were inoculated
in the old way, where the wounds were considerable, and were
dressed every day; which  mode of treatment kept them from scab-
bing, by which means this process was easily observed ; but in the
present  method  of inoculation it is  hardly observable ; the sore
being allowed  to  scab, the  slough  and  scab  unite and drop off
together.  The same indistinctness attends the eruptions  on  the
skin; and in those patients who die of, or die while in, the disease,
where we have an opportunity of examining them while the part is
distinct, this slough is very evident.
  This slough is the cause of the pit after  all  is cicatrized ; for it
is a real loss of substance of the surface of the cutis;  and in pro-
portion to this slough is the remaining depression.
  The chicken-pox comes the nearest in external appearance to the
small-pox ; but it does not commonly produce a slough.
  As there is generally no loss of substance in this case, there  can
be  no pit.   But it  sometimes  happens, although but  rarely, that
there is a  pit in consequence of chicken-pox; then ulceration has
taken place on the surface of the  cutis, a common thing in sores.
  In the present case, besides the leading circumstances mentioned
in the case of the  mother, corresponding with the  appearances on
the  child, and the external  appearances themselves, we have in
the fullest sense the third  and real  or  principal character of the
small-pox, viz., the slough  in every pustule ; from all which,  I think,
we  may conclude, that the child had caught  the small-pox in the
womb; or at least a disease, the effects of which  were similar to
no other known disease.
   In opening  the bodies of those who had either  died of, or died
while under, the small-pox, I always  examined  carefully to see
whether any internal  cavity, such  as  the oesophagus,  trachea,
stomach, intestines, pleura,  peritoneum, &c,  had  eruptions upon
them or not; and never finding any in any of  those cavities, I be-
gan to suspect  that  either the skin itself was the  only part of the
body susceptible of such a stimulus, or that the skin was subject to
 some influence to which the other parts of  the body were not  sub-
ject, and which made it alone susceptible of the variolous stimulus.
 If from the  first  cause,  I then concluded it must be  an original
 principle  in the animal ©economy.   If from the second, I then sus-
 pected  that external exposure was the cause;  and  I was the more 
OF A WOMAN WHO HAD THE SMALL-POX, ETC.    109
led into this idea, from finding that these eruptions often attack the
m?,U ^  nd throat» two exposed parts; add to which, that we gene-
rally find the eruptions  most on the exposed parts of the bodv, as
the face, &c.                              r
   With these ideas in my mind, I thought I  saw the most favoura-
ble opportunity of clearing up this point.   I therefore very attentive-
ly examined  most of the  internal cavities of  this child;  such as the
peritoneum, pleura, trachea, inside of the oesophagus, stomach,  in-
testines,  &c, but  observed nothing  uncommon.  I have already
observed, that in this child  the face and extremities were the fullest
similar  to what happens in  common ;  from all  which I may be
allowed to draw  this conclusion, that the skin is the principal part
which is  susceptible of the variolous stimulus,  and  is not affected
by any external influence whatever.
   The communication of  the  small-pox to  the child in the womb
may be supposed to happen in two ways; one by infection from the
mother, as is supposed in  the above case;  the other, by the mother's
having absorbed  the small-pox  matter from  some other  person,
and  the  matter being carried  to the  child from the  connexion
between  the two,  which we may suppose done with or without first
affecting the mother.
   Testimonies and opinions  are various with respect to these two
facts.  Boerhaave seems to  have been  led  by his experience to
think that such  infection  was not  communicable; for we find
that he attended  a  lady, who having,  in the  sixth month of her
pregnancy, had the confluent small-pox, brought forth at the regu-
lar period a  child, who showed  not the least vestige of his mother's
disease.
   His  commentator, however,  Van  Swieten, supports  a different
opinion  (see his Comment., vol. v.).   He quotes  a case  from  the
Philosophical Transactions, vol. xxviii., No 337, p. 165, of a woman
who, having  just  gone  through a mild sort  of  small-pox, was,  by
means of a strong dose of purging physic, thrown into a miscarriage,
and  brought forth  a dead  female child, whose whole body was
covered with variolous pustules full of ripe matter: but this history
is founded only on the relation of a  midwife to a clergyman, and
therefore not absolutely to be depended upon as accurately stated :
however, it is more than probable that there was a case as described,
and that there were really eruptions on the skin of the child similar
to the small-pox.
  Van Swieten likewise  mentions what Mauriceau relates of him-
self.  This author, testifies that he had often heard his father and
mother say that the  latter,  when  big with him,  and very near her
time of delivery, had a painful attendance on one of her children,
who died  of  the small-pox on the seventh day of the eruption; and
that on the day following  the death of this child Mariceau came into
the world, bringing with him five or six true pustules of the small-pox.
  It does not  appear, however, from this recital whether  or not
Mauriceau passed through  life free from any posterior infection ;
                               11 
110          HUNTER ON THE ANIMAL CECONOMY.
but admitting that this eruption of Mauriceau's was truly the small-
pox, yet I should very much doubt his  having  caught it from the
child who died of it : as it should seem  that the pustules of Mauri-
ceau were of the same date with those of the child who died.   Van
Swieten appeals to a more recent case, which had  been reported  to
him by persons of great credit, and is  recorded in  the Philos.
Trans, vol. xlvi., p. 235.
  " A woman big with child, having herself long ago had the small-
pox, very assiduously nursed a maidservant during the whole  pro-
cess of this  disease.  At the proper time  she  brought a healthy
female child, in whose skin Dr. Watson asserted  that he discovered
evident marks of the small-pox, which she must have gone through
in the womb; and  the same physician pronounced that this child
would  be free from future infection.  After four years her brother
was inoculated ;  and Watson obtained permission  of the parents to
try the same experiment on the girl.   The  operation was performed
on both children in the same manner, and the pus used in both cases
was taken from  the same patient.   The  event, however, was dif-
ferent: for the boy had  the regular  eruption, and got well; but the
girl's arm did not inflame nor suppurate.   On the tenth day from
the insertion of the matter she turned pale suddenly, was languid
for two days, and afterwards was very well.  In  the neighbourhood
of the  incision there appeared a pustule, like those pustules that we
sometimes observe in persons who, having had the disease, attend
patients ill of the small-pox."
  In the Epistles of T. Bartholinus, Cent. II., p. 682, there is the
following history :  " A poor  woman, aged  thirty-eight years, preg-
nant, and now near the time of delivery, was seized with the symp-
toms of the  small-pox, and had a very numerous eruption.  In this
state she was delivered of a child, as full  of variolous pustules as
herself.  The child died soon after  birth ; the  mother three  days
afterwards."  Van Swieten infers that the mother and  the  child
were in this case infected at the same time;  therefore, the child not
infected by  the mother.
   Dr.  Mead asserts that when a woman in the small-pox suffers  an
abortion  the foetus is generally full of the contagion ;  but that this
does not  happen always.   This variety, he says, depends on the
state  of  the mother's  pustules when the  child  is  born; that is,
whether  they are or are not in a state  of purulence.  Whence  he
has observed it sometimes to happen that on the  second  day  from
the birth, or the third, or any day before the  eighth, the disease
caught from the mother shows itself in  eruptions on  the child.
   Dr.  Mead here relates the history of a ladv of quality, of which
this is the substance.  A lady, in  the seventh month of  her preg-
nancy, had  the confluent small-pox, and on the eleventh day of the
disease brought forth a son, having no signs of the disease on  his
body ; and she died on  the fourteenth day.   The infant having lived
four days, was seized with convulsions, and, the small-pox appearing
died.  The  doctor infers from hence that, the suppuration being in 
        OF A WOMAN WHO HAD THE SMALL-POX, ETC.     HI

some measure completed on the eleventh day, the mother's disease
was communicated then to the fcetus, and made its appearance on
the child after eight days.
  If there be  no abortion, Dr. Mead pronounces that the child will
ever be free from the disease, unless the birth should happen before
the maturation of the pustules.   He brings a case to prove that the
foetus  in the womb may be infected by the  contagion of which the
mother does  not  partake.   " A woman, who had long before suf-
fered the small-pox, nursed her husband, under that disease, towards
the end of her  pregnancy; and  was  brought  to bed  at the due
time.   The child was  dead, and  covered  all  over  with variolous
pustules."
  With respect to the case quoted from  Mauriceau, it has been
proved by Sir George Baker (Med. Transact., vol. ii., p. 275), that
Dr. Mead  drew  a conclusion  from it directly contrary to the
author's meaning.  The negative opinion  appears evidently to be
supported by  that history.
  Sir George Baker mentions in the  same paper the case of two
pregnant women who  were inoculated at Hertford.   They both
had the small-pox favourably, and afterwards brought forth their
children perfectly healthy at the usual time.   Both  these children,
at the age of three years, were inoculated with effect.
  Sir George Baker likewise mentions a case  which fell under the
observation of Dr. Clarke of Epsom.  " A woman towards the end
of her pregnancy had  the small-pox, from which  she narrowly
escaped.  Five weeks after the crisis she was delivered of a healthy
female child,  who having numerous  marks  on her skin was judged
by all who  saw her to have undergone  the same distemper before
her birth.  However, at the  end of twelve months she  had the
small-pox in a very severe  manner.  Both  the  mother and child
were lately living at Epsom."
  Since, then, we  see  that it is very probable  that  the small-pox
may be caught  from  the  mother when she is infected, it may be
asked why does not this happen oftener 1 In answer to this we may
suppose that this is not so ready a way as when the child is exposed
to catch it  after the birth, as we find too that a difference can be
produced  after birth;  viz., inoculation  is  a much readier way of
catching it than what is called  the natural way.  It may  likewise
be said that many women  who are with child, and have the small-
pox during pregnancy, do not recover; therefore both mother and
child  die  before the disease can have time to produce eruptions
upon the child.  Finally, in many of those cases where the mother
recovers, there is sometimes produced a miscarriage,  which also
hinders the  infection from taking  place in the child.   However,
many women go  through the whole disease, and the child shows
no  marks of the small-pox.
   Thus have I stated  facts relative to the present subject, with
some of the best authorities on both  sides of the question; and shall
now leave  the reader to form his own judgment. 
112
HUNTER ON THE ANIMAL CECONOMY.
       10.  SOME OBSERVATIONS  ON DIGESTION.

  The  paper which I  formerly presented to the Royal Society,
« On the Stomach itself being digested after Death," was published
in 1772, in the 62d volume of the Philosophical Transactions, and
has attracted  the attention  of Spallanzani* and others.   In the
course of these my observations I shall  make some remarks upon
the  experiments  and opinions of these  gentlemen, compare  them
with those  of Reaumur,f and, having given  some general facts ot
my own upon  digestion, shall  conclude  by adding a  copy of the
above-mentioned paper, with the hope that others will take up the
subject in a more enlarged point of view, and prosecute an inquiry
which is of so much consequence in the  investigation of the opera-
tions of the animal ceconomy.   I cannot at present spare sufficient
lime to  give my opinions at large on this subject, with all the ex-
periments and observations I have  made upon it; but as soon as I
have leisure I  shall lay them before the public.
  To discover new parts has  been  a  principal  object in the re-
searches of' the young  or practical anatomist; but the connexion,
arrangement, mode of action, and uses of the whole, or of particular
organs, have  more commonly been reserved for the consideration
of those whose views were extended further, and whose powers of
reasoning had been enlarged by habits of  observation and inquiry.
Curious and speculative men have  likewise made attempts in this
way,  but  often  without  being sufficiently acquainted with the
structure of the parts they were about to  consider, and consequently
ill informed respecting  their relations  and connexions with one
another. Not contented to reason from  those which were  most
obvious, which might have led to useful  knowledge, they have been
directed by what best  suited their fancy, and have principally at-
tempted the most obscure and intricate.   Generation, or the  mode
of continuing the species, and  digestion, or the means of preserv-
ing the individual, have been with them the great objects of inquiry ;
yet it does  not appear  that they have  been very successful.  Al-
though digestion,  as being one of the most important operations of
the animal ceconomy, and most obvious  in  its  effects, supplies a
number of  facts to assist in  ascertaining its powers, little has been
hitherto made out towards investigating the various circumstances
under which it is performed.
  The mode of dividing the food for the increase of its surface, in
some animals, suggested one method of explaining the process of

  * [Spallanzani's observations on digestion appeared first in his work called
Fisica Animate e  Vegetable, 12mo. 1782; a  translation of which was  published
in London,  with the title ' Dissertations relative to the Natural History  of
Animals and Vegetables,' in 1784.]
  f [" Sur la Digestion des Oiseaux," Mem  de I'Acad. des Sciences de Paris 1752
pp. 266—307, and pp. 461—495.] 
OBSERVATIONS ON DIGESTION.             113
digestion ; and the secret'ion of a juice, which was supposed to have
the power of  converting vegetable and animal matter into a fluid
proper for the purposes of nutrition, furnished another.  Both these
opinions have had their advocates; and while one party contended
for a mechanical power, supposed to exist in the gizzard, the other
had recourse to  a chemical power, and considered fermentation as
the great agent  in digestion.  They were, however, rather specula-
tive philosophers than practical  anatomists,  and  have frequently
been misled with respect to the very facts and observations whose
result was to decide the truth of their opinions.   What, for instance,
does it explain in digestion, that the force of the gizzard of a turkey
is found equal to four hundred and seventy-three pounds?   Does it
afford a better solution of our  doubts  than we should derive from
determining the  force of the mill that grinds the wheat into flour 1
Or, on the other hand, will the most correct idea  of fermentation
enable us to account for the  various phoenomena in  the operation of
digestion?   But we can have no very high  idea of experiments
made by men who, for want of anatomical  knowledge, have not
been able to pursue their reasoning  beyond the simple experiment
itself.
   The great object should have been an endeavour to discover the
universal agent  in digestion; for the digestive organ is evidently
constructed  in a different manner in  different animals. The me-
chanical power  for the division of the  food is  not  universal ; and
those gentlemen  who consider this power in the gizzard as the im-
mediate cause of digestion, forgot that the same effect was produced
in other classes of animals with a different structure of stomach,
by means of the  grinding teeth.  Thus, while  the gizzard favoured
the theory of the  mechanical reasoner, that idea  was again destroyed
by the membranous structure of the  stomach in  many  animals,
which equally supplied the chemist with arguments in favour of
the process of fermentation.
   It is more difficult than those gentlemen imagine,  to acquire on
this  subject information sufficiently accurate to be able to explain a
process so complicated as that of digestion. There are in Nature's
operations always two obvious extremes; and  the mind of man
eagerly adopts that which  accords with  some principle to which
he is attached, and with which he is  best acquainted, the  inter-
mediate connexions and  gradations, as being  less  striking, not so
forcibly affecting a superficial inquirer.
   It happens,  unfortunately, that those who from the nature of their
education are  best qualified to investigate  the  intricacies, and im-
prove our knowledge of the animal ceconomy, are compelled to get
their living by the practice  of a profession which is constant em-
ployment.   The only educated men who have leisure are those  of
the Church, some of whom we  frequently  find  commencing philo-
sophers and physiologists, though they have not had  that kind  of
education which would best direct their pursuit.  Experiments, it
is true, may be made by men of this description;  but these  must 
114          HUNTER ON THE ANIMAL CECONOMY.
neither be much complicated, nor  have any immediate relation to
those branches of knowledge with which they have had few oppor-
tunities  of being acquainted:  at best, they will  seldom go further
than to explain a single fact.   To look  through  a microscope and
examine the red globules of blood,  to view animalculse, and give a
candid account of what they see, are points on which such inquirers
may be allowed to indulge themselves ;  but it is presumption in them
to affect  to reason of a science in which they can have but  a very
superficial knowledge, or to expect to throw light on subjects  that
they have not taken the previous steps to understand.  It should be
remembered that nothing in  Nature  stands  alone; but that every
art and  science has a relation to some other art or science, and that
it requires a knowledge  of those others, as far  as this connexion
takes place, to enable us to become perfect in that which engages
our particular attention.
.   These strictures  are  applicable to  all those who  have   made
experiments to explain  digestion.   The effect of the  mechanical
powers  being  easily understood, those  who considered  digestion
mechanically have in general explained them justly as far as  they
applied to the gizzard ; but their reasoning went no further, and they
supposed these effects to  be digestion.   Those  again  who  took it
up  chemically, being little  acquainted  with chemistry and totally
ignorant of the principles of the animal ceconomy, have erroneously
explained the operations of the animal  machine as subject  to the
laws of chemistry.
   The first  inquirers into digestion, struck only  by the extremes of
structure, the gizzard, and membranous stomach, paid no regard to
the gradations  leading from the one to the other ; which, if properly
examined,  would  have  materially assisted  them  to  explain the
functions of the stomach.
   Vallisneri, considering the power of the gizzard in one view only,
imagined it would be  as  liable to be  affected  by the  mechanical
powers  necessary for digestion as the grain which was to be digest-
ed.; therefore supposed  the existence   of a solvent.   But though
Vallisneri is entitled to no merit from this idea, as the  premises are
false, yet this opinion of his set Reaumur to work, and has been the
means of bringing several curious facts to light.*   The experiments
of Reaumur were first made with  a  view to confute that opinion,

   * [In this historical sketch, so rare in the writings of Hunter, of the opinions
entertained by previous physiologists on the subject of digestion, the suggestion
by Tyson of the existence and use of a solvent or corrodent fluid ouo-htAto have
had a place.  In his Anatomy of a Rattlesnake he  observes, "The food, before
it can prove aliment, must be comminuted, and broken into the smallest particles ;
which in these membranous  stomachs I can't see how it ean be performed but
by corrosion   A principal menstruum in doing this I take to be that liquor which
is discharged by the glands  that are seated, in some, at the beginning of the
 throat, and are called sahval; or just above the stomach or gizzard of birds, and
callad the echinus ; or in others in the stomach itself, and called the glandulus
 coat, and such I take the inner coat of the stomach  of our rattlesnake to hP "_
 Philos. Trans., xiii. 1683, p. 33.] 
OBSERVATIONS ON  DIGESTION.             115
and therefore birds having gizzards were adapted to his purpose.
In this pursuit he only attended to such parts of the experiments as
best accorded with his own opinion, vet carefully guarded against
every possible  accident  that might affect their  accuracy.   Had
trituration been the immediate cause of digestion, his experiments
on the gizzards of birds were unnecessary; since it would have been
sufficient  to have examined the food after it had been masticated by
the teeth of animals  who have grinders, the teeth and gizzard
answering one  and the same  purpose.  But the circumstance of
animals which  masticate their food  in  their mouth having also a
stomach,  should  have taught  that  there was  something Inore in
digestion  than trituration.
   Reaumur's first experiments were made to ascertain the strength
of the gizzard,  with  its effects, to  prove  that  sharp cutting sub-
tances when swallowed  in no way injured  its internal coat, and
that the common food of the bird was not  dissolved  whenAguarded
against its action.  Yet,  after all  these proofs, he  seems to doubt,
and says, " Are we to conclude that grinding alone is sufficient to
convert the grain and other aliment into a  matter  proper for the
nutrition of the animal, without undergoing any other preparation?
Several reasons seem to oppose this  : trituration alone might reduce
the grain  into a flour ; but flour alone is not chyle."  " From the
smell of the aliment (taken from the gizzards of birds) are we not
led to conclude that it undergoes  a  fermentation ?  This smell may
be said  to arise from the  liquor with which the aliment is mixed ;
but is it likely that juices do not dispose to fermentation substances
in which  it is  so easily excited?  Fruit  and flour, made  into a
paste, require little more  than heat to make them ferment."  From
these experiments, made  with  a  view to  prove  that digestion is
carried on by trituration, Reaumur  was led  to suppose a solvent.
But as there  are some birds whose stomachs do no  not seem suffi-
ciently strong to have the power  of  trituration, he selected the
buzzard as being of that kind, and  the fittest for the  subject of his
experiments, from the circumstance of its throwing up whatever is
solid  and  indigestible; therefore, without killing the  bird, he could
know the result, and repeat the experiment as  often  as he thought
necessary.
   From the stomach  in the buzzard being  incapable of trituration,
he  concluded that a solvent was necessary  for digestion;  but, to
preclude all mechanical effects  of the stomach, in his experiments
he employed tin tubes filled with meat, which, after the tubes had
remained  twenty-four hours in  the stomach of the buzzard, was
reduced to three-fourths of its size, was like threads, and was neither
putrid, sour, nor volatile, but insipid.  On this effect he made his
remarks, which are very pertinent.   In another experiment, which
was still  more  accurate  and conclusive, he  was  convinced of the
action of  a solvent.  He  then tried the soft bones of young animals,
and found they  were digested;  and that though the hard bones
were  not acted on  so readily, yet, by returning the same bones
several times into the stomach, they were digested at last. 
116
HUNTER ON THE ANIMAL CECONOMY.
  Reaumur  was  next  anxious  to  know  if such  birds  as were
intended by Nature to live upon  meat could also digest vegetables;
but the result was not so satisfactory.  He gave bread to his buz-
zard,  which upon being  returned  had  the  appearance of having
been  chewed.   He  next  tried a piece  of ripe  pear, after having
been twenty-four hours in the  stomach, had lost some of its weight,
and had the  appearance of being  boiled or baked ;  and thence he
concludes  that its  powers are too weak to digest vegetables so as
to nourish the animal.
  To ascertain the nature of the liquor which had such powers, he
tasted the jelly to which the meat and bone had been reduced, sup-
posing that it must  be well  impregnated with this fluid;  but he
could only distinguish  a  bitter  or  a saltish taste.   To  have an
opportunity of more certainly determining the nature of this solvent,
he made his buzzard swallow small tubes filled with sponge, which
imbibed fifty grains of this liquor, having the same taste as the jelly,
and  changing blue  paper to  a  red.  He  tried the effects  of this
liquor on meat out of the body, with comparative experiments in
water; and  after  twenty-four hours the  meat in the water was
become putrid; but  that  in the  liquor from the stomach  was only
softened, not dissolved.  To see how far the analogy held good in
membranous  stomachs, he gave two bones to a dog, which being
killed after twenty-six hours, they were found lessened in size, and
become as soft as horn. He found that the stomach of the dog did
not  alter the shape of any  of his  tubes.
  He conveyed grass and hay, inclosed  in tubes, into the  stomachs
of ruminating animals, which substances were  not digested, but
appeared as if macerated.
  Let us enumerate  the experiments and facts made out  by Reau-
mur.
  The gizzard was not hurt by acting upon glass, which  it ground
to a powder.
  The stomach or gizzard had hardly any visible motion.
  The force of the gizzard was  ascertained.
  The size of the stones found in the gizzard was in proportion to
the  size of the bird.
  The stomach of a buzzard  digested bone, from which he  con-
cluded the gastric juice had a  solvent power;  but it did  not digest
bread, although it acted in a slight degree on fruit.
  He made experiments with  the gastric juice.
  The juice in the ruminating  animals' stomachs produced no effect
on hay or  grass when inclosed in tubes.
  Reaumur's experiments, although not complete, paved the way
for future  investigation; and  Spallanzani, proceeding on  the same
ground, has not only confirmed them by his own, but has established
several points not completely made out by Reaumur; for in some
instances  Reaumur  gave  up  the  point too soon, especially in the
experiments respecting the buzzard's power of digesting vegetables.
Reaumur not possessing general knowledge sufficient to direct him 
OBSERVATIONS ON DIGESTION.
117
in his pursuits, was  necessarily confined  to  what he was most
master of, the mere making experiments.  Being neither an anato-
mist  nor  a physiologist,  he has  not been  perfectly  just in  his
description of parts, having considered the crop and the oesophagus
leading from it to the gizzard as two distinct stomachs; but this,
however, is only to be set down as a piece of anatomical ignorance,
not affecting the  subject in the least.  Spallanzani is also deficient
in his anatomical knowledge ; yet it must be owned that his experi-
ments, as far as they go, are in themselves conclusive;  but like all
mere experiment-makers, he is not satisfied even with those which
are  clear and decisive, but  multiplies  them  most unnecessarily,
without varying them to elucidate other  and  essential parts of the
same subject.  I  think  we may set  it down as  an axiom, that
experiments should not be  often repeated which tend merely to
establish a principle already  known and admitted;  but that  the
next step should be, the  application of that  principle to useful pur-
poses.  If Spallanzani had employed half his time in this way, and
had  considered digestion  under all the various states of the body
and stomach, with all the varieties of food, both natural and artifi-
cial, he had employed his time much better than in making experi-
ments without end.
   The food of animals in general being  composed either of vege-
tables, animals, or both, and a  solvent  admitted  as an  agent in
digestion, it only remained  to prove, that the effect of the process
of digestion was to produce from  these various substances an
animal matter, similar in all animals who live on such substances.
But  the application  of  principles requires  more  than  simply the
knowledge of the principle  itself, and  therefore those who  cannot
reason from analogy, or draw general conclusions  from a few con-
vincing facts, and who require to have every relative conclusion or
inference proved by an experiment, must be  pleased with Spallan-
zani ; but  he  must tire even those  whom he informs, and much
more those who read his works  in expectation of something new.
   To make comparative experiments upon the digestive power, the
different animals destined for that purpose should be under  similar
circumstances as  far as  relates to digestion ;  they should  be equal
in age, for the growing eat more than the full-grown, and of course
digest faster;  which point, therefore, can be best ascertained by
selecting those in  each class of animals which have attained their
full growtlj.  They should  be equal in fatness,  for this makes a
very material  difference in  the  powers  of digestion in  the same
animal; and they should be equal in health, a circumstance which,
of all others, probably makes the greatest difference in the powers
of the stomach.   In  comparing animals of the  same  class,  the
atmosphere should likewise  be of the same temperature;  for the
different classes of animals are variously affected by  the  same
degree of heat.  Experiments made upon snakes and lizards in the
winter will differ greatly from those made in the summer, while
similar experiments made on dogs will have nearly the same result 
118          HUNTER ON THE ANIMAL CECONOMY.
m
 i. both seasons.   Nor will the powers of the stomach  be found
always equal in the same class.  Sleeping animals of the quadruped
kind, as hedgehogs, do not digest in the winter, but in the summer
only ; therefore the conclusions to be drawn from  experiments made
respecting the digestive powers in the one, are not at all applicable
to those made in the other season.
  Spallanzani observed  that the snake digested food faster  in June,
when the heat was at 82° and 83°, than in April, when it was  only
60°; from  whence he concludes, that heat  assists digestion ;  but
this heat is not the immediate, but the remote cause of ihe increased
power; heat having produced in  the animal greater necessity for
nourishment,  and of course- greater powers, gastric  juice  was
secreted faster or in  greater quantity.
  As a proof that heat does not act as an immediate, but only as a
remote cause in assisting digestion, I shall mention the effect it pro-
duced upon a hedgehog, the  subject of Mr.  Jenner's third  experi-
ment on the  heat of that animal, related  in another part  of  this
work.
  " The hedgehog, while the heat of  the stomach was  at 30°,  had
neither desire for food,  nor  power of digesting  it; but when in-
creased by inflammation in the abdomen to 93°,  the animal seized
a toad which happened  to be in the  room, and, upon being offered
some bread and milk, it immediately ate it.   The  heat roused up
the actions of the animal ceconomy; and the parts being unable to
carry on these actions without being supplied with nourishment, the
stomach was stimulated to digest, to afford them that supply."
  Spallanzani also mentions the slowness of digestion  in  serpents,
and quotes Bomare, who gives an account of a serpent at Martinico,
in whose stomach a chicken had remained for three months without
being completely digested, the feathers  still  adhering to the skin.*
The truth of this fact I  should very much  doubt, especially in so
warm a climate as that of Martinico, where  I  must suppose the
digestive powers to be constantly  required;  unless  there is in
 Martinico, as in colder climates, a  torpid  season,f where the act
of digestion is not necessary ; but in that  case the serpent would
not have swallowed the chicken.
   At Belleisle, in the beginning of the winter 1761-2, I conveyed
 worms and pieces of meat down the throats of lizards  when   they
were going into winter quarters, keeping them afterwards  in a cool
 place.  On opening  them at different periods I  always,found the
substances which I had introduced entire, and without any altera-
 tion: sometimes they were in the stomach ;  at other times they had

  * Bomare, Diet. d'Histoire Nat.
  f [This conjecture is true; the dry season  in some tropical climes is that
 during which reptiles  and  insects retire to their  hiding-places and become
 torpid ; they are awakened and called into activity by the showers of the rainy
 season.
  The tenrec, a mammiferous animal of Madagascar and the  Mauritius, re-
 sembling the hedgehog, also sleeps in a state of lethargy from April to Novem-
 ber, when the mean temperature exceeds our summer heat.] 
OBSERVATIONS ON DIGESTION.
119
passed into the intestine; and some of the lizards that  were pre-
served alive voided them towards the spring, with but very little
alteration in their structure.   So that digestion is regulated by the
other actions of the body : warmth requires action  suitable to that
warmth;  the body requires  nourishment suitable to that  action;
and the stomach being called upon, performs the office of digestion.
  Nothing can show more clearly that the secretion of  the gastric
juice is increased in proportion  to the call for nourishment in the
body,  than what happened to Admiral Byron and Captains Cheap
and Hamilton, when shipwrecked on the west coast of South Ame-
rica, who, after suffering months of hunger and  fatigue, were  re-
duced  to skin and bone;  yet when they came to good living, Byron
thus expresses himself: "He (viz., the governor) ordered  a  table
to be spread for  us, with cold ham and fowls, which only we  three
sat down to, and  in a short time  despatched more than ten men with
common appetites would have done.  It is amazing that our eating
to that excess we had done, from the time we first got among these
kind Indians, had not killed us ;  we were never satisfied, and used
to take  all  opportunities, for  some months after, of filling our
pockets when we were not seen, that we might get up two or three
times in the night to cram ourselves.  Captain Cheap used to de-
clare that he was quite ashamed of himself."
   Spallanzani has  made several  attempts to prove what few will
subscribe to, that stones in the  gizzards of birds  are of no use
towards the breaking or grinding down  the  grain ;  and that they
are picked up without design.  These  stones have long been  sup-
posed  to answer the purposes of trituration, and have been con-
sidered as affording  assistance  to the stomach, in the manner of
teeth,  and of course as  being necessary to  the  act  of digestion.
Spallanzani combats this opinion;  but  as stones  are  universally
found  in gizzards, and it was necessary to account for the mode of
their being conveyed there, he attributes it to chance.  But we find
that the gizzards which have most occasion for them,  and are most
able to use them, are likewise best supplied with them : to corrobo-
rate which facts may be added what we  observed before, that  in
the larger gizzards  are found  the largest pebbles.   In a  turkey two
hundred were found ; in  a goose, a thousand; which  could not de-
pend entirely upon chance.   In trying whether the stones were  of
service, Spallanzani introduced tubes, needles, and lancets into giz-
zards  in which  there were  but very few stones, yet found  them
broken.   In this experiment  these substances had been forty-eight
hours  in the gizzards; whereas  in the former experiments, with the
same kind of tubes, thirty-six hours was the longest time; in another,
eighteen hours;  and in another, the breaking of them  was begun in
less  than two hours; therefore  the experiments were not perfectly
fair, as the times were not equal.  What he thinks the most con-
clusive is, that where he had taken care there should be no stones,
the hard indigestible substances were acted upon  much in the  same 
120
HUNTER ON THE ANIMAL CECONOMY.
way as when there were stones; but in this experiment he  does
not sive  the  time, which is  verv accurately stated in most of the
others.                                                    ,
   He discovered that the inner surface of the stomach was not hurt
by such substances; and indeed it is scarcely possible for the inner
coat of the stomach of  a fowl to be pierced  by such as are  even
sharp-pointed, the quantity of its motion  being so inconsiderable as
hardly to make them pass through its inner coat.   But the principal
cause of their being harmless arises from the motion being lateral,
and not pressing perpendicularly to  the axis, one surface sliding in
a contrary direction to the other, and that not in  a straight, but in
a circular direction, as will be explained hereafter.
   In considering the strength of the gizzard, and its probable effects
when compared with the human stomach, it must appear that the
gizzard is in itself very  fit for trituration; we are not, however, to
conclude that stones are. entirely useless;  for if we compare the
strength of the muscles of the jaws of animals which masticate  their
food with those of birds which do not,  we  shall say that the parts
are well  calculated for the purpose of mastication ; yet we are not
from thence  to infer that the teeth  in such  jaws are useless,  even
although we  have proof that the gums  do the business when the
teeth are gone.  U stones are of use,  which  we may reasonably
conclude they are, birds have an advantage over animals having
teeth, so  far as stones are always to be  found, while  the teeth are
not renewed.   Spallanzani concludes, "  That  we have at length a
decision of the famous question concerning the  use of these pebbles,
so long agitated by authors  ; it appearing that they are not at all
necessary for  the  trituration of the  firmest food,  &c,;" but says,
" He will, however, not deny that when put in motion by the gastric
muscles,  they are  capable of producing some effects on the contents
of the stomach."   Now if we  constantly  find in an  organ  sub-
stances wiiich  can only be subservient to the  functions of that
organ, should we deny them  to be of any use because the part can
to a certain degree do its office'without  them ?
•  To account for pebbles being found  in the  gizzard, Spallanzani
supposes  the  birds to  have  picked  them up by chance, or not to
have distinguished between  their food  and these stones.  But  it
appears singular that only those which have gizzards should be so
stupid; and he owns that Redi and himself found that birds died of
hunger, yet without having picked up more stones than usual, which
we might suppose they would have done  if  they had  not had a
choice, or could  not have distinguished stones from the grain on
which they feed.
   The stones  assist in  breaking  the grain, and by separating  its
parts in the beginning of the process,  and afterwards by rubbing off
the surface already digested, allow the gastric  juice to come more
completely in contact with the whole.
   It has  been said, that the motion of  the  gizzard is so small  as 
OBSERVATIONS ON DIGESTION.
121
 hardly to  be observable, and that it  cannot be felt by the hand.
 Put as ^s  cavity is very small, and must  be capable of  adapting
 itself  to  the quantity it contains (or it  could not possibly grind),
 much motion is not  necessary for  the  purposes of trituration:  a
 swelling and collapsing, like the motion of the heart, would have no
 effect.  The extent of motion in grindstones need  not to be the
 tenth of an inch, if their motion is alternate and in contrary di-
 rections.   But although the motion of the gizzard is hardly visible,
 yet we may be made very sensible of its action  by putting the ear
 to the sides of a fowl while it is grinding its food, when the stones
 can be heard moving upon one another.*
   It may be remarked, that the motion of the whole intestinal canal,
 from the fauces  to  the anus, is naturally so slow,  as not to be ex-
 cited into quick actions.   The food passes  slowly along  the oeso-
 phagus ; and in a man, fluids which might be expected to  act even
 by their own gravity, descend  but slowly;  yet I think we may be
 certain that the oesophagus  has  always  a regular contraction, and
 that the lower parts  must relax in progression as it contracts above;
 so that no position of the body makes  any difference in this action.
   Upon exposing the stomach in living  animals it does not appear
 much agitated  or  affected, even  by being  handled  or otherwise
 irritated.    The same  thing  may be observed in the whole track of
 intestines:  and we  find that when the faeces are  expelled by the
 action of  the gut alone, that the explusion  is slow ;  the  stomach
 and rectum, however, can be emptied at once; but that is done by
 the abdominal and  other muscles.  We know that the action of
 vomiting  is performed entirely by the diaphragm  and  abdominal
 muscles ;  and we know that by the same action the contents of the
 rectum can be expelled.  Neither  is  any other power  required to
 empty the stomach  in vomiting, these  muscles being  often capable
 of forcing the bowels  themselves out of  the  abdomen,  and of  pro-
 ducing a rupture.  It  is not necessary the stomach itself should act
 violently to produce an evacuation of  its contents ;  nor is it even
 necessary it should  act at all; for the lungs themselves do  not act
 in the  least  when  any extraneous matter  is to be thrown up;  and
 coughing  is to the lungs what vomiting  is to the stomach.f  The

  * [Harvey makes a similar observation on birds of prey : " Falconibus, aquilis,
 aliisque avibus ex praeda viventibus, si aurem prope admoveris dum ventriculus
jejunus est, manifestos intus strepitus, lapillorum illuc ingestorum, invicemque
 collisorum  percipias."—Opera Omnia, 4to., p. 208.  These investigations by
 means of the ear relative to the internal actions of animal bodies deserve a place
 in the history of auscultation.]
  f [The conclusion which Hunter deduces from philosophical and just analogies,
with respect to the share performed by the stomach in the  act of vomiting,0has
 not been considered satisfactory, at least if we may judge from the experiments
 which have subsequently  been made with a view to determine that point.  But
 perhaps M. Majendie was not aware of what our illustrious physiologist had
 written on the subject, as he introduces his experiments to our notice as if the
passive state of the stomach in vomiting had never before been suspected : " On
a cru long-temps que le  vomissement dependait de la contraction brusque et con-
                                12 
122
HUNTER ON THE ANIMAL CECONOMY.
muscles of respiration are the  active part in emptying the lungs,
and can  act  both naturally and  preternaturally.   The muscles of
the thorax and abdomen do  not  act naturally on the contents of
the abdomen, but often  act preternaturally,  producing an evacua-
tion from its viscera.
  There is this difference in the action of the parts  in  coughing
and  vomiting: the  cough is performed  by the proper muscles of
respiration, which are those of expansion, supported by  the abdo-
minal, while the diaphragm is passive.
  Vomiting is performed by the abdominal muscles and diaphragm,
while those of inspiration are supporting this  action.
  In coughing the ribs are  suddenly depressed, which diminishes
the capacity of the thorax ;  and  that the diaphragm may not be
allowed  to sink down  and increase the capacity of the  thorax,
which would counteract the  depressors  of the ribs, the abdominal
muscles at the same time act, which supports the diaphragm in its
place, and probably  may by this action assist in bringing down the
ribs.   To give as much force to this  action  as possible, the glottis
is shut till the  action is begun, and  then the glottis open instan-
taneously, which  obliges the depressors of  the ribs to  begin the
effort with their full  action.
  The proper muscles of  inspiration do not  tire so soon in this
action as the abdominal, for in  violent coughing the muscles of the
abdomen become sore.
  In vomiting  these  actions are  reversed.   The muscles of the
cavity of the abdomen act, in which is to be included the diaphragm;
so that the capacity of the abdomen is lessened, and the action of
the diaphragm rather raises the ribs; and there is also an attempt
to raise them  by  their proper muscles, to make a kind of vacuum
in the thorax,  that the oesophagus may be rather  opened than shut,
while the glottis is shut so  as to  let  no air  enter the lungs.  The
muscles of the throat and fauces act to  dilate  the fauces, which is
easily felt by  the hand, making there a  vacuum, or what is com-
monly called a suction; so that when all these actions take place
together, the stomach is immediately emptied.
  In violent coughing we  find that  a kind of  mixed  action takes
place; for although  the diaphragm has not acted, yet the stomach
is so much squeezed as  to discharge its contents;  and it affects the
diaphragm, which is often thrown into action, and brings on vomit-
ing at the same time ; therefore violent coughing palls the stomach.
  There is reason to believe that the natural motion in all stomachs

▼ulsive de l'estomac," &c.;  and then goes on to detail his notorious experiment
on the dog, for whose stomach he substituted a pig's bladder; by which he
proved, that when filled with fluid and put  into  a situation to be pressed upon,
the contents of the bladder would flow out.   By dividing the phrenic nerves, and
paralysing the diaphragm, Majendie also proved that  the abdominal muscles
alone were capable of producing vomiting; and by another experiment, he satis-
fied himself that the diaphragm alone was sufficient for that act when all the
abdominal muscles had been dissected off, and the peritoneum left entire.] 
OBSERVATIONS ON DIGESTION.
123
is regular;  and I am more inclined to be of this opinion from what
takes place in the stomach of animals which are covered with hair,
and which lick their own bodies, and of  such as feed on  whole
animals which are likewise covered with  hair.  In the stomach of
the  calf, for instance, which  licks its  skin  with its  tongue, and
swallows whatever is attached to the rough surface of that organ,
balls of hair are often found; and on examining their  surface the
hairs in each hemisphere seem to arise  from a centre, and to take
the same direction, which is circular, corresponding to what  would
appear to be the axis of this motion, and resembling  what we see
in different parts of the  skin of animals  whose hair takes different
turns.   This regularity in the  direction  of the hair, in such balls,
could not be produced if there was not a regular  motion in the
stomach.   This motion is also proved in the dog; for I have seen
a ball of this kind that had been thrown  up from  a dog's stomach,
where the same regularity in the turns of the hair  was very evident
and complete.   The same motion seems also to take place in the
bird kind ; and of this the cuckoo is an example, which, in certain
seasons living on caterpillars, some of which have hairs of a con-
siderable length on their bodies, the ends of these are found sticking
in the inner horny coat of the stomach  or gizzard, while the hairs
themselves are laid flat on its surface ; not in every direction, which
would be the case if there was no regular motion,  but all one  way,
arising  from a central point placed in the middle of the horny part,
and the appearance on  the surface of both  sides of the gizzard
evidently corresponding.*  These two facts prove, in my opinion,
a regular circular motion taking  place in  the gizzard and  mem-
branous stomach, and therefore, most probably, something similar
is carried on in  stomachs of all  the various  kinds.  Indeed this
motion  in the stomach is so considerable, that when there  is no
horny defence, we find the coats sometimes pierced by hard pointed
substances.   Thus, the cows which feed  on the grass of bleeching-
grounds have their stomachs, especially  the  second stuck full of
pins ; and fish which prey upon and swallow other fish entire, often
have their stomachs pierced by the bones.
   Spallanzani calls the  inner coat cartilaginous, whereas, in fact, it
is a horny substance, forming an inner cuticle, but  differing in some
respects from the common cuticle; this  horny substance not only
differs in structure from the common cuticle, but in its attachment,
from cuticle, nails, and  hoofs.  The cutis where  it is covered by
such substances, has a vast number of villi on its surface, which pass
into corresponding perforations in the  cuticle ; from this structure
of parts, when the cuticle, nails, or hoofs are separated, their inner

 * [The appearance is so regular, that this hairy lining of the gizzard has been
mistaken, for  a natural peculiarity of the cuckoo.  In one of  these gizzards,
which was exhibited at a meeting of the Zoological Society, I found the supposed
gastric hairs under the microscope to present the complex structure characteristic
of those of the larva of the tiger-moth (Ardia Coja).  See  Proceedings of the
Zool. Soc. 1834, p. 9.] 
)24          HUNTER ON THE ANIMAL CECONOMY.
surface appears to be full of small perforations, and the cutis from
which they have been removed is villous; and these villi are more
numerous in some  parts than in others, where the sense of  touch is
required to be delicate or acute.   But the inner lining of the gizzard
is just the reverse,  that surface of the horny substance which is in
contact with the gizzard  being villous, and when separated, the
inner surface of the gizzard appearing perforated.  These  villi are
either the last-formed parts of this horny substance, or are the fibres
of which  the horny  coat  is composed.  It is  probable that  this
horny substance takes the form of villi that it may be more  firmly
connected with the gizzard, in which acute sensation is not required.
  I may remark here, that the experiments made  on the digestion
of ruminating  animals  have  been very  deficient,*  arising from
this process in them being more complicated than  in the stomachs
of other animals,  and  requiring attention to be  paid to certain
circumstances, which cannot take place in stomachs of only one
cavity.
  The  circumstance mentioned  by  Spallanzani, of  ruminating
animals voiding the tubes by the anus, shows that  the  whole food
is not necessarily returned into the mouth to be chewed a second
time ; for if it were, the tubes would certainly come up  likewise,
and would as certainly be thrown out of their  mouths as improper
to be chewed, a circumstance which often really happened.  But it
was  hardly necessary to make  experiments to  ascertain  whether
ruminating animals digested meat, when we know that  in some
cold  countries the cattle are fed on dried fish, and most animals eat
their own secundines: indeed  the circumstance of animals  living
upon both animal and vegetable food might have taught us that the
mode of digesting  both  (whatever it is) was the  same; therefore
all that was wanted must have been to discover that mode  ; except
we could absurdly  conceive that two different  modes  might take
place in the same stomach at the same time.
  Spallanzani gives the opinion  of  authors respecting digestion;
and so anxious  is he to combat the idea of its being fermentation,
that  he  will hardly allow that fermentation ever takes  place  in the
stomach.  That fermentation can go on  in the  stomach  there is
no doubt; but when  that happens, it  arises from the powers of
digestion being defective.   Milk, vegetables of all kinds, wine,  and
whatever has sugar in its composition, become much  sooner sour
in some stomachs than they would if left to undergo a spontaneous
change out of the  body; and even  spirits  in particular stomachs,
almost  immediately  degenerate into a very strong acid.  I  am
inclined to suppose that it is the  sugar which is converted  into
spirit, and  the  spirit  into acid ;  consequently a glass  of brandy,
from being much stronger, because less  diluted, most  probably

   * [This deficiency has recently been supplied by M. Flourens, in an elaborate
senes of experiments  made on living sheep, in which fistulous communications
had been established between the external surface and the different cavities of
the stomach.  See Annates des Sciences Naturelles.'] 
OBSERVATIONS ON DIGESTION.
125
contains as much matter likely to become  acid  as  half a pint of
wine.   In other  substances, besides  those mentioned  above, the
fermentative process (unless prevented by that of digestion) appears
to begin sooner in the stomach than out  of the body.   All oily
substances, particularly  butter, very soon become rancid  after
being taken into the stomach; and this rancidity is the effect of
the first process of the fermentation of  oil.  Mr. Sieffert has been
able to  restore rancid oils to their original sweetness, by adding to
them their due quantity of fixed air;*  the loss of which I consider
as the first process in this fermentation,  similar to what happens in
the fermentation of animal and  vegetable substances.
   Animal food does not so readily ferment in the  stomach when
combined with  vegetables as when it is not; for  the vegetables
running more quickly into fermentation, preserve the meat from
putrefaction.   Put a piece of meat and some  sugar, or bread, into
water, and let them stand in a warm place; the  bread and  sugar
will begin to  ferment, the  water will become sour, and the meat be
preserved ; but the acid  becoming weaker,  as  the fermentation
advances towards the putrefactive, the meat at last begins to acquire
the same putrid disposition.!  Yet this last part of the process can-
not, I think, take place in the stomach, as a succession of acids will
be formed, by which  the  meat will be  preserved sweet till it is
digested ; the formation of this  acid in the stomach, most probably,
not preventing the digestion of those substances which are incapable
of being rendered acid.
   Bread allowed to remain in the stomach of a dog for eight hours
is so much changed that it will not run into the vinous fermentation,
but when taken out and kept in a warm  place  becomes putrid;  its
putrefaction,  however, is not so quick as a solution of meat that has
been in  the stomach for the same length of time.   Similar effects
are produced when milk and bread are the food administered; and
perhaps the gastric juice, when in sufficient quantity, will always
prevent the vinous fermentation.
   Spallanzani's next trials were to determine whether the gastric
juice had the power  of recovering meat  already  putrid: a fact
which  might have been  proved  by one experiment; for if very
putrid meat is given to a dog, and the dog  killed after some time,
the meat will  be found  sweet, and  all putrefaction at  an end.
Therefore his allowing fresh meat to continue a longer or shorter
time in the  stomach was  immaterial,  as it could  not become
putrid.
   It appears from the above facts  that the  stomach has not  so
much power  in  preventing the  acetous fermentation in vegetables
as in correcting the putrefactive disposition in animal substances.
For although this cannot be  certainly known in those who eat both

  * Physical and Chemical Essays, by SirTobern Bergman.
  f Of this Sir  John Pringle was not aware in making his experiments on this
subject.
                                12* 
126          HUNTER ON THE ANIMAL CECONOMY.
animal and  vegetable food, yet it does not  appear that the putre-
faction  of animal substances, where  nothing else is  eaten, takes
place so quickly in the stomach as  the change which  is produced
in vegetables; the acetous disposition is therefore either stronger
than the putrefactive, or it more  readily takes place: and  indeed
the living body shows this sufficiently; for wc  very often find  an
acid thrown up, but seldom or never anything putrefactive.
  It may be admitted as an axiom that two processes cannot go on
at the same time in the same  part of any substance; therefore
neither vegetable nor animal substances can  undergo  their spon-
taneous changes while in the act  of being digested, it being a pro-
cess superior in power to that of fermentation.   But if the digestive
power is not perfect, then the vinous and acetous fermentation will
take place in the vegetable, and the putrefactive in the food of those
animals which live wholly on flesh; although in the last I  imagine
but very seldom.  The gastric juice, therefore, preserves vegetables
from running into  fermentation, and animal substances from  putre-
faction ;  not from  any antiseptic quality in the juice, but, by making
them  go  through another process,  preventing the  spontaneous
change from taking  place.   In the greater  number of stomachs
there is  an acid, even although the  animal has lived  upon meat for
many weeks; but as this is not always the case, we must suppose
it is only formed occasionally.  Whether the stomach has a power
of immediately secreting this acid, or first secretes a  sugar which
afterwards becomes acid, is not easily ascertained;*  but I should
be inclined  to suppose, from  analogy, the last  to  be the  case:
animals in health seeming to have the  powrer  of secreting sugar;
for we find it in the  milk, and  sometimes  in the  urine, in  conse-
quence of disease.  Acid sometimes prevails in the stomach  to  so
great a degree as to  become a disease, attended with  very disagree-
able symptoms;  the stomach converting all substances which have
a tendency to become acid into that form.  To ascertain whether
there was an acid naturally in the  stomach the most satisfactory
mode was to examine the contents before the birth, when the diges-
tive organs are perfect, and when no  acid could  have  been pro-
duced  by disease, or anything  that  had been swallowed.- Ac-
cordingly, in the slink-caff, near  the full time, there was  no acid
found in  the stomach, although the contents had the same coagulat-
ing powers with those of animals who have sucked.
  As  we find  stomachs possessed of a power of dissolving  the

  * [The singular case of the man with an external fistulous communication with
the stomach, detailed  by Mr. Beaumont, who has so ably availed himself of the
circumstance to elucidate  several obscure points in the process of digestion has
afforded the means of determining this question.  The stomach in its°empty and
inactive state  contains no gastric juice; but when mechanically stimulated, as
by touching the inner surface with the  bulb of a thermometer that secretion is
immediately poured out, and manifests the usual acid properties.  (Beaumont:
" Experiments and Observations on the  Gastric Juice, and on the Physiology of
Digestion.")] 
OBSERVATIONS ON DIGESTION.
127
 whole substance of a bone, it is reasonable to suppose that its earth
 is destroyed by the acid in the stomach.
   The stomach appears not only to be capable of generating an
 acid, but also to have the power of producing air : which last effect,
 I believe, arises from disease.  It is not easy to account for the
 formation  of  this air; yet  as the stomach is a reservoir for  sub-
 stances disposed to  ferment, it  might reasonably be supposed to
 arise  from the food going  into that process.   But  this, in my
 opinion, will not account for the vast quantity of air frequently
 thrown up from the  stomach, even where  food has not been swal-
 lowed for a considerable time, and where digestion appeared to
 have been completed.  For we must conclude this process to have
 been completed, if the food was not found to have disagreed with
 either stomach or bowels, and that the stools were good.  When
 the gout falls on the stomach the quantity of air thrown up is often
 immense, and the same thing may be observed in some cases com-
 monly called nervous ; yet the process of digestion will not account
 for  this formation of  air,  as no air is  to be found in healthy
 stomachs;* neither  is  it-to be accounted for from a defect in
 digestion, as that would probably be productive of worse conse-
 quences.
   I am inclined to believe that the stomach has a power of forming
 air, or letting it loose, from  the blood, by a kind of secretion.   We
* cannot, however, bring any absolute proof of this taking place in
 the  stomach,  as it  may in all cases be  referred to a  defect in
 digestion; but we have instances of  air being found in other cavi-
 ties,  where no secondary  cause  can be  assigned.   I have been
 informed  of persons who  have  had  air in the uterus or vagina,
 without having been sensible of it but by its escaping from them
 without their being able to prevent it;  and who, from this circum-
 stance, have been kept in  constant alarm lest it should make a
 noise in its passage, having  no  power  to retard it  as when it is
 contained  in the rectum.  This fact  being so extraordinary made
 me somewhat incredulous, but rendered me more inquisitive, in the
 hope of being enabled to ascertain and account for it; and those of
 whom I have  been  led  to  inquire  have  always made the natural
 distinction  between air  passing from the vagina and by  the anus:
 that  from the anus they feel and  can retain, but that in the vagina
 they cannot;  nor are they aware of it till it passes.  A woman,
 whom I attended  with the  late  Sir John Pringle, informed us of
 this  fact,  but mentioned it only as a disagreeable  thing.  I was
 anxious to  determine if there were  any  communication between
 the vagina and  rectum, and was  allowed to examine, but  disco-
 vered nothing uncommon in the structure of these parts.   She  died
 some time after; and, being permitted to open the  body, I found
 no disease either in the  vagina or uterus.   Since that time I have

   * In all my experiments on digestion, in dogs, I have never been able to detect
 any air in the cavity of the stomach. 
128
HUNTER ON THE ANIMAL CECONOMY.
had opportunities of inquiring of a number of women concerning
this circumstance, and by three or four have been informed of the
same fact, with all the circumstances  above-mentioned.  How far
they are to be relied upon I will not pretend to determine.   I have
likewise found  air in  the cellular membrane  in gunshot wounds,
that had passed some way under the skin, without being able to
account for its being there by any mechanical effect of the ball.
  That air is either  formed from the blood, or let  loose by some
action of the vessels, both naturally and from  disease, is an unde-
niable fact.  We find air formed in some fishes, to answer natural
purposes;  for in those  whose air-bladders do not communicate
externally (many of which  there  are) we must suppose it to have
been formed  there.  We also find it in animals after death; and I
have a piece of the intestine of a hog which has  a  number of air-
bladders in it.   Mr. Cavendish  was so kind as to examine this air,
and he found " it contained a little  fixed air; and  the remainder
not at all inflammable, and  almost completely phlogisticated."  I
have often seen such vesicles on the edges of the lungs;  but these
may be supposed to have been a kind of aneurismal  air-cells filled
from the trachea, and are circumscribed and impervious, so that in
the state we find them they have no communication with the exter-
nal air.  In one instance I have discovered air in an  abscess, which
could  not  have been  received from  the external air, nor could it
have arisen from putrefaction.  The case is as follows:
  A lady, about forty years of age, had been afflicted with com-
plaints in the  bladder and parts connected with it.  From the symp-
toms, her disease  was supposed by some to be the stone,  though
upon examination no stone was found ; and she had also an umbi-
lical hernia, for which I had been consulted.  She grew gradually
worse, and from  being  lusty,  became a thin  woman.  A small
tumour appeared in the groin, and  the skin  over it became  red,
similar to an  abscess when  the matter is beginning  to point exter-
nally ;  but before her death this subsided.   A few days  before she
died I was desired to examine a  swelling on the lower and right
side of the belly, extending nearly from  the navel to the spine of
the ilium on the right  side.  It was tense, evidently contained air,
and could  be  made to sound almost like a drum.  It had come on
within a few weeks, and  I was puzzled to account for it, there being
clearly no connexion between that tumour and the umbilical hernia.
I was inclined to suppose it to be  a ventral hernia, containing the
crccum and part of the colon, filled with air; but as  she had stools,
as there were no symptoms of a strangulated gut nor any  uneasi-
ness in the bowels, as I could not make the air recede, but felt it as
if confined to that part, I own I could form no  conjecture what the
case really was. The woman dying in a few days, I was permitted
to examine the body.  That I might not interfere with the tumour,
or umbilical hernia, I  made an opening into  the abdomen on the
right side of the linea alba, and on examining the cavity of  the ab-
domen, found everything natural, except a small portion of the epi- 
OBSERVATIONS ON DIGESTION.              129
ploon adhering to the inside of the navel; the parietes of the abdo-
men corresponding with the tumour being in a natural  state.  On
pressing the tumour by the hand, air was heard to make its escape;
whether by the  vagina or anus was at first doubtful;  but on ex-
amining with more attention,  it was  discovered  to come from
between the labia.  I  next opened the tumour externally, and let
out the air, which was not in the least putrid, and was contained
in a sac tolerably smooth on its inside, made up of compressed cel-
lular membrane, the abdominal muscles and  tendons forming the
posterior  surface, which extended  as  low as the inferior  edge of
Poupart's ligament.  The contents of the abdomen were tolerably
sound;  but when I inspected  the viscera  contained in the pelvis,
they were found adhering to each  other;  the bladder to the body
of the uterus: the broad ligaments and ovaria to the uterus; and
on examining these adhesions, I discovered a cavity between the
bladder, uterus,  and vagina, on the right side, something like an
abscess.  From the right side  of this cavity there was  a canal as-
cending to the brim of the pelvis, in the course of  the round liga-
ment, as far as to the going out of the iliac vessels, which it seemed
to accompany;  and  this canal,  when  it  passed  from behind
Poupart's  ligament, communicated with the tumour above men-
tioned.   I then  endeavoured to discover if there were any com-
munication between the rectum  and the abscess, but could find
none, the gut appearing to be quite sound.  Having removed the
whole contents of the  pelvis, with the canal  leading to Poupart's
ligament, and the ligament itself, with such of the abdominal muscles
as composed part of the sac, I found both the rectum and the vagina
perfectly sound.   The  uterus  had a polypus forming on its inside;
neither the rectum nor uterus had any connexion with the abscess;
but there was a small communication between the  abscess and the
bladder, that portion of the bladder which made part of the abscess
 being very much diseased.
   From this history of the appearances of the tumour before death,
and the particular account I have given of the dissection, the reader
may be able to draw his own conclusions relative to the origin of
the air.  It certainly appeared to have been formed in this bag;
 and it was only  towards the latter end of her life  that it could have
 made its escape into the cavity of the bladder, for  it was not possible
 to squeeze the air out of the tumour when I first  saw her; but just
 before  death it  became more flaccid.  It  could  not  be formed  or
 let loose, in consequence of putrefaction, for the air itself was free
 from any smell; and although the cavity  between the vagina and
 bladder had on  its internal  surface the irregular ulcerated appear-
 ance of an abscess, yet that on the abdomen had  not, was tolerably
 smooth, and  had rather the appearance of having  been formed  in
 consequence of some foreign matter accumulating there.
   This circumstance, of an animal having the  power of forming
 air, or separating it from the juices by a kind of  secretion, appears 
130          HUNTER ON THE ANIMAL CECONOMY.
at first view to  be supported by the experiments  of Dr. Ingen-
housz.*
   The Doctor observed, that when we immerse our bodies "ma
cold  or warm bath," or "by plunging the hand and  arm even in
cold water," globules of air soon appear upon the skin; and to be
certain of the air coming from the body, he took all the necessary
precautions to prevent the external air being carried into the water
along with the body (which would certainly be a consequence if the
body or part were immersed quickly, or when dried).   But although
his experiments seem to prove this opinion, yet I imagine there is a
circumstance the Doctor did not attend to at the time, which renders
them very fallacious;  for he  did  not  consider that  water  for  the
most part contains a great deal of air; therefore the globules of air
might as  readily come  from the water  as from  the  body, which
makes it necessary to ascertain, by experiment, from whence the
air comes which is attached to the body when immersed in water.
   Water  takes  up air in proportion to  its coldness, until it loses
the property of  water, and becomes solid : upon this  principle we
may account for globules of air being found  attached to  the skin
when a part of the body is immersed in water colder than itself; for
when  we immerse the  whole  body we increase the  heat of  the
water, especially that  next to the skin; and if we immerse only a
part,  as an arm, it being commonly in  a smaller quantity of water,
the water immediately surrounding it  is also warmed.   As a  proof
that it is the air from the water, and  not  from  the surface of  the
body,f it matters not what the substance is that  is immersed if it is
but warmer than  the water;  for a piece of  iron, heated to about
150°, immersed  in water about 70°, will warm the water in contact
with it so as to  make  it part with its air.  This effect of heat is
further proved  by making another trial, with only this difference,
that the iron be ten  degrees colder  than  the water; in that case
little or no air will be separated, and of course  no bubbles observed.
The bubbles of  air do not appear to arise entirely from the degree
of warmth of the water, but also in  some measure from  a solid
body being immersed in it, that seems to have a power of attract-

  * Experiments upon Vegetables, proving their great power of purifying the
common air, &c.
  j "Count de Milly, in the Berlin Transactions for  the year 1777, published
experiments to show that there is  an excretion of air, or, as it  is termed, 'an
aerial transpiration,' from the whole surface of the human body while it remains
in warm water; but Dr. Pearson found, on repeating  these experiments, that
there was no appearance of aerial bubbles on  the surface of the cuticle durino
bathing in warm water that had been previously boiled, so as to expel the afr
usually mixed and united to  river and spring water.   The  human body, when
immersed in the bath at Buxton, and kept at rest in it for some time, was covered
with air-like bubbles; but these bubbles  appeared in the  same manner on  any
solid body whatever that was placed  in it.  It is  therefore supposed that the
attraction to the human body of the air, commonly suspended in water, especially
when heated to the temperature of a warm-water bath, has been mistaken for an
excretion of air from the cuticle.' 
OBSERVATIONS ON DIGESTION.
131
ing the air, whose affinity to the water  is now weakened by heat;
for simply heating the water to the same degree will not separate
the air, as we find that no bubbles are ther/produced.   The power
of attracting  the air appears therefore in some sort to  depend upon
the solidity of the body immersed;  at least bodies have a greater
number of bubbles in proportion to their solidity; for upon making
comparative  experiments between iron, stone, wood, and cork, the
air separated from the water upon the surface of the iron and stone
is  in considerable quantity;  that upon  the wood very small, and
scarcely  any at all upon the cork.
   As these observations  on the generation (or. secretion) of air in
cavities seemed  to have a connexion with the present inquiry, I
thought they  might properly enough be introduced here ; but I shall
content myself with having mentioned the circumstance, and pursue
the subject of digestion.
   To determine with  absolute certainty in what particular portion
of  the canal  this important process  of  digestion is performed, is
perhaps impossible; but there is the greatest reason to believe that
it is principally carried  on in the stomach, with a little variation
in different animals.  We may venture  to affirm that it does not
at  all  take place  in  the  long and  contracted  oesophagus of  the
quadruped, the secretion of that part being a slimy mucus, possessed
of no power  similar to that of the gastric juice, but only intended
to facilitate the passage of the food into  the stomach.
   Neither has the mucus secreted in certain parts of the oesophagus
of birds, as in the crop of those which  have one, any digestive
power; while, on the contrary, we  find the  lower end, which is
extremely glandular, to be capable of secreting a juice with all the
properties of  the  gastric ; and that passing into the cavity of the
stomach  becomes  a substitute in this class of animals for the de-
ficiency of the secretion of the stomach  itself, which in some is
lined with a horny substance, and in  others with a cuticle.   Even
in birds the  seat of digestion is chiefly  in the stomach, the juice
secreted in the lower part of the oesophagus passing into that cavity;
and the mucus secreted by  the other  parts of the oesophagus, as in
the crop  of those  which have one, has no such power.  But if any
digestible substance should  be retained  in the oesophagus, as may
happen in many of those which swallow whole animals, digestion
may even go on  in its inferior portion.  In the gull and heron,
which  take down snakes and fish entire, the tails may remain in
the oesophagus till the head  is digested in the stomach ; and in such
cases the tail itself may be acted upon in that situation.
   As a further proof that digestion is carried on principally in the
stomach, let us observe what happens to the yolk of an egg in  the
bird newly hatched.  The  yolk is not  in the  least consumed in
the time of incubation, but appears to be reserved for the nourish-
ment of  the  chick between  the  time of  hatching, and its either
being supplied with food  by its parents, or being able to procure it
for itself; for we  find, that although the  yolk passes into the gut at 
132          HUNTER ON THE ANIMAL CECONOMY.
 some distance from the stomach, yet it is carried up to the stomach
 to be digested ; and I have even seen it in the crop, being retained
 there till wanted.
    In those animals whose stomach consists of several cavities, the
 precise place where digestion is carried on has not been ascertained.
 I think,  however, that in the ruminating class, in which it has four
 cavities, it may be set down as a fact that digestion goes on in the
 fourth, which is best proved by feeding the animal with a substance
 that does not require any kind of preparation for digestion, such as
 milk.  If a calf be killed about half an hour after it has sucked its
 mother,  we shall  find the whole milk  in  the  fourth  cavity firmly
 coagulated, and formed into a ball, while the first, second, and third
 cavities  contain only such food as  requires mastication, or what
 other preparation is necessary to fit it for digestion.  Such animals
 have the power of conveying the food from the oesophagus, either
 to the first  or fourth  cavity, according to the nature of the food;
 and for this purpose  there is  a groove  leading directly from the
 oesophagus to the fourth stomach, which I suppose can be converted
 into a canal when wanted.
   It  is  possible  that digestion may likewise be carried on in the
 duodenum, especially in its upper part, if either the intestine secretes
 the same juice with the  stomach, or that some of the gastric juice
 and part of the food have passed  into the intestine before it has
 been  completely turned into chyle.*
   Although the stomach is the'seat of digestion, it is not solely ap-
 propriated to that purpose; and in many animals these  organs are
 not to be considered as only a digesting bag or  bags, but  in part
 as  a reservoir for food.   This is most remarkable in the ruminating
 animals,  where the first stomach or bag is  merely a reservoir, and
 in this respect  analogous to a crop.   It is  the  same in  the porpus,
 and, I believe,  in most animals of this class; although it cannot be
 supposed that  those  return the food who have not the power to
 masticate.  In some  animals which do not ruminate there is not
 the same necessity for distinct pouches,  the  stomach consisting
 either ot  one bag singly, or of  stomach with appendages, as in the
 peccan.   But the  whole organ is not endowed with the  property of
 ttCrl^&   ,g,aStricJuice'there beinS a  Part whose structure is
 very different from that appropriated to  digestion, and covered by


 converted in the duodenum af m hP !,n,i. I • ♦  the Vy]°?S una,tered " was
  Majendie attemptedto  subjectthis ™2' '"? ¥*" ™d ™ydme-
 from not having insured the continuance^^thZ K° ?"** eXPeriment' but failed
 necessary situation.  He found oninLducin^6 eXPenme"ted on in the
 duodenum  ofahealthydog, that i^an hour khfHhP,eCe •'7™ flesh int0 the
 weight was slightly diminished, buuhere was^i ^ "T** to?he reCtum : its
 tion of its surface.  In another experiment h^fixeda ™ cha"^thaln.a ^iscolora-
 intestine with a thread; after the lapse 0  three hom^f^'V" the SmaU
 weight: the fibrin had been principally acted Up0n " wh't    lost about  half its
cellar, and extremely fetid?  SetFrlcis E^^p^^X £«$J 
OBSERVATIONS ON DIGESTION.
133
a cuticle, as in the first, second, and third stomach of the ruminat-
ing animals and in the first stomach of the  porpus.  The peccari,
the common  hog,  and the  rat, are  likewise  instances of  this;
and the same circumstance takes place, in a smaller degree, in the
horse.
   This increase in the cavity of the stomach, beyond what is neces-
sary for digestion alone, is peculiar to the animals that take in more
food  than is  immediately wanted,  or whose food  is of a nature
which requires a certain degree of preparation prior to digestion.
The crop of the  eagle, and perhaps the first stomach of  the porpus,
are of the first kind; the  crop  in  the gallinaceous fowls, and the
first stomach in  ruminating animals, of the second.*  It is the dis-
position  of such animals  to fill  these  cavities;  and the quantity
which they are capable of containing makes them seldomer require
to be filled;  it is probable, likewise, that it  is the sensation excited
by this fulness which  gives  satisfaction to the animal, and  takes
off the further desire for food, an  effect  similar to what is pro-
duced in other  animals from filling the stomach itself; and  these
having no such provision, are longer and oftener employed in pursuit
of food.
   I should  be apt  to consider  the power of the  gastric juice  to
coagulate milk,  and  some  other animal mucilages,t as a test of the
stomach  being  the  seat of digestion; for  although  milk maybe
coagulated by other substances, yet when found in that state in the
stomach it is probably for the purpose  of digestion, milk and many
other natural substances requiring to be coagulated before they can
be digested.   I have found this coagulating power in the stomach
of every animal  that  I have examined for that purpose, from the
most perfect down to reptiles;J and in the appendages which I have

   * [According to this difference in their functions,  we find that the crop of the
eagle is relatively smaller than that of the fowl, and the passage of its contents to
the stomach is  more direct and easy.  The first stomach of the porpus is still
smaller in comparison with the rumen of the sheep; and besides acting as a
storehouse for the food, digestion goes on in it to a considerable extent.  This is
effected, not by secretion from its own parietes, which, as Hunter observes, are
lined with a cuticle, but most probably by the gastric juice regurgitated into it
from the second stomach, which is highly glandular.  The flesh offish is found
separated from the bones, and these in different stages of softening, in the first
stomach ; indeed, the construction of the aperture of communication between the
first and second  stomachs of the porpus is such, that food can pass into tha
latter only in a very comminuted state.]
   | Milk is the substance commonly known to be coagulated by the gastric juice;
but I find that it has also the same power over the white of an egg.  Give to a
dog some raw egg, and kill him half an hour  after  he has swallowed it, the egg
will be found coagulated in his stomach, as if boiled. The crystalline humour
in the stomachs of fishes is likewise found coagulated.
   X [By " reptiles" there is reason to believe Mr. Hunter meant'creeping things,'
as insects and worms.   The ' Reptilia ' of modern naturalists he invariably calls
by the Linnaean name 'Amphibia,' or by his own term, 'Tricoilia.'  In  the In-
troduction to the Series of Digestive Organs, (Phys. Catalogue of the Hunterian
Collection, vol. i.) he says, "In some reptiles  the teeth are placed in the oesopha-
gus," alluding to preparations of a Nereis ; and in a manuscript, published  in
                                  13 
134
HUNTER  ON THE  ANIMAL  CECONOMY.
considered as only reservoirs preparatory to digestion, (as the first
stomach in the  ruminating animal, and the crop in birds,) 1  have
discovered no such power.  Yet it is not the digestive power which
coagulates those substances, complete coagulation taking place even
where digestion does not at all go on.*   This is evident every day
in children who suck, and who have diseased stomachs ; for we see
them throw  up  the milk coagulated, and discharge  it undigested by
stool.   A very  remarkable instance  occurred  in a child that had
lost entirely the power  of digestion, yet the milk taken down came
away strongly  coagulated, some  even  as firm almost as cheese;
which seems to  show that the coagulating power is  seldom wanting,
although the other may.
   The gastric  juice is"  a  fluid somewhat  transparent, and a little
saltish or brackish to the taste; but whether this is  essential or only
accidental is not  easily determined.  Indeed there  are very few of
our secretions which have not some  salt in them; it being found in
the tears, the saliva, the secretion of the glans penis, of the glands
of the urethra, and  in the first  and  the  last  milk secreted in the
udders of animals.
   I am not inclined to  suppose that there is any acid in the gastric
juice as a component or essential part of it, although an acid is very
commonly discovered,  even when no vegetable matter has been in-
troduced into the stomach.f   The acid may be increased in some


the same volume  of the Physiological  Catalogue, there is proof that he experi-
mented on an  insect with especial  reference to the seat of the digestive power.
After detailing the peculiarities of the digestive organs in  the flesh-fly (Musca
vomitoria), he observes:
  " The bag belonging to the first-described canal is to be considered a craw or
crop, viz., a reservoir for the food to be ready for digestion ;  and as the abdomen
contains almost every internal part of the  animal, it is obliged to be situated in
this cavity.  That it is a reservoir for food I proved by experiment:  I kept some
of these flies fasting for some time: I then  gave them milk, which they drank
readily; and when I thought they had filled their bellies, I put them  into spirits,
which assisted in  coagulating the milk wherever it might be.   On opening the
abdomen, I found  this bag full of curd  and whey, as also some in the stomach.
I kept a fly for twelve hours without food, and then gave  it milk, and killed it,
and found no milk in the crop, but it had got through almost the whole tract of
intestines : here the animal had immediate occasion for food, therefore the milk
did not go into the crop.  This experiment at the same time shows that, probably,
every part of the intestines  digest, for the stomach  makes no distinct bag."]
   * [Or rather the digestive power may be equal to the coagulation, but net to
the completion of the digestion of the coagulable substances.]
  f The only trial to which I  ever put the gastric juice was with the syrup of
violets, to ascertain if it was acid ; and in many of the trials  the colour of the
mixture was changed to red.  But it is necessary, for the accuracy of the experi-
ment which is to determine this fact,  that the animal should not be fed upon
vegetables for some time before the trial is made, these being liable  in some de-
gree to become sour; therefore it. is hardly fair to make the experiment on the
contents of the stomach of animals who live upon vegetables.  In many trials of
this kind we may be deceived, and led  to suppose an alkali; for certain animal
secretions being of a yellow cast, when such are mixed with the syrup of violets
the mixture is changed to a green.  The truth of the experiment may, however,
be known by adding a little acid ;  for if the green  has been  produced merely by 
OBSERVATIONS ON  DIGESTION.
135
diseases, and in others the disposition to form  it may be destroyed,
which  may be the  reason why, by a  kind of instinctive principle,
many girls  are fond of eating sour fruit and  of drinking vinegar;
while others, on the contrary, from a different cause, often eat chalk,
lime, and other substances of that  sort.  But  the  acid  not being
always found, it is not yet determined on what occasions it is formed,
or in what manner it is destroyed.
   The process of digestion differs from every other natural opera-
tion in the change it produces on  different bodies ; yet it is by no
means fermentation, though it may  somewhat resemble it.   For
fermentation, a  spontaneous  process, is  that natural succession
of changes  by  which  vegetable and  animal  matter is reduced  to
earth;  therefore must be widely different from  digestion, which
converts both  animal and vegetable  substances into chyle, in the
formation of which there cannot be a decomposition similar to fer-
mentation.
   Digestion is  likewise very different from chemical solution, which
is only a union  of bodies by elective attraction.   But digestion is
an assimilating process;  and  in this respect  is somewhat  similar
in its action  to  that excited by morbid poisons.   It is  a  species of
generation, two substances  making a third;  but  the  curious  cir-
cumstance is its converting both vegetable and animal  matter into
the  same kind  of substance or compound,  which no  chemical pro-
cess can effect.   The chyle is compounded  of the  gastric  juice

a mechanical mixture, it will become immediately a scarlet, by being then a mix-
ture of red and yellow ; but if the secretion is not only of a yellow colour, but
of an. alkaline nature, it will  also continue green;  and by adding a little more
acid than what saturates the alkali the colour will then become orange.a
  a [Various opinions have been entertained as to the acidity of the gastric juice.
Spallanzani believed it to be a neutral fluid.  Carminati could detect no acid in
the gastric juice of carnivorous animals and mixed feeders, but found it to exist
in that  of  vegetable feeders.  (Ueber die Natur des  Magensaftes,  Wien,  1785.)
Helm, who examined the gastric juice in a patient with a fistulous  opening in the
stomach, also states that it contains no sensible acid.  (Zwei Krankengeschicten,
Wien, 1803.)  The same cause of error has probably operated in each of the pre-
ceding  cases, viz., not making a sufficient  distinction between the  ordinary
mucous secretion of the stomach and the peculiar fluid which is poured out from
the stimulus of the contact of food, or any innutritions substances.  In the experi-
ments of Tiedemann and Gmelin the ordinary secretion of the stomach in fasting
horses  and dogs was found to be  almost  neutral,  or very slightly acid;  but on
stimulating the surface by means of stones, (by which any cause of error from
a change of fermentable substances, as alluded to by Hunter, was  avoided,) then
the secretion manifested unequivocally the presence of acidity.   Beaumont  has
more fully established the acidity of the gastric juice in the work  before quoted.
He observed in the man with gastric fistula that the gastric juice was poured out
from numerous  minute clear points or papilla?.  It is a clear inodorous fluid, with
a somewhat salt and very marked acid taste, like  that of thin mucilage which
has been  soured with  muriatic  acid.   It dissolves in water, wine, and alcohol;
slightly effervesces with alkali; decomposes slowly, and retards the decomposi-
tion of  animal matter.  Saliva imparts to the gastric juice a blue colour and a
frothy appearance.  Chemical analysis shows the gastric juice to contain both
the muriatic and acetic acids, alkaline phosphates, muriate of soda,  magnesia, and
lime, and an animal matter which is soluble in cold but not in hot water.] 
136
HUNTER ON THE ANIMAL CECONOMY.
and digestible substances when perfectly converted ;  and it is pro-
bable that the quantity of gastric" juice may be nearly equal to inai
part of the food which is really  changed into chyle,   it  so, n
demonstrates the necessity of a very quick  secretion, to  supply a
quantity so very considerable;  but with  this  advantage, that it is
not lost to the constitution.                                  f
  The progress of the conversion of food into  chyle  may be  otten
seen in the stomach  of  animals  at different times  after  feeding.
Fishes are good subjects on which  to make  observations  for this
purpose, as  they swallow their food  whole; and as that food is
commonly fish, and often too large to be completely admitted into
the stomach.  As they do not masticate their food, it is not adapted
to the cavity of the stomach ; and therefore part of it is often  found
lying in the oesophagus;  a circumstance by which the comparative
progress of digestion is rendered more obvious.
  It may  also be well observed in the stomach of a  dog,  in which
the whole quantity taken has been swallowed at once.  In the great
end the food  will be but little altered; towards the  middle, more;
and towards  the pylorus it will be  similar to what is found in the
duodenum.*
  From the structure of the stomach in ruminating animals they
are badly  adapted to  assist our inquiries on  this subject, because
metallic balls, or whatever is swallowed in  so  hard and solid a
form  as to be unfit for  digestion, requiring  to be  ruminated, will
often be thrown out when  returned into the  mouth for that pur-
pose ; or it may lie a  long time in the first stomach without  being
either thrown up or passed  into the fourth, as  I have frequently
seen; therefore  the chance of its getting into the fourth  stomach
in a proper time to fit it for the object of an experiment being very
uncertain, no great light can be derived  from trials made on animals
of this class.
  Live or fresh vegetables, when taken into  the  stomach, are first
killed, by  which a flabbiness in their texture is produced,  as  if they
had been  boiled ; and then they can be acted upon  by the gastric
juice.
  Meat appears to  undergo no change  as preparatory to  digestion,
but at once to submit to its union with  the gastric juice ;  for, after
having been  acted upon, it seems first to lose  its texture, then be-
comes cineritious in colour, next gelatinous, and last  chyle.   The
first change  made upon milk and some  other secretions, as the yolk
and white of an egg,  is coagulation;  after which the gastric juice
begins to  acquire a power of uniting  with them.
   The first change which is produced on animal substances out of
the body, either by being exposed to heat or by becoming spontane-

  * [The cardiac and pyloric portions of the stomach possess the digestive power
in very different degrees,  it being much  more energetic  in the latter.   In the
stomachs of Carnivora and Rodentia the two portions are commonly found divided
by a constiiction; and the same hour-glass contraction of the stomach is occasion-
 ally met with in the human subject.  See Sir Everard Home, Phil. Trans. 1817,
 p. 347.] 
OBSERVATIONS ON DIGESTION.
137
 ously putrid, is similar to  the  second of the three changes which
 takes place in digestion; and is only preparatory to the complete
 change, whether that  be digestion or putrefaction.
   It appears from many experiments that the digested or animalized
 part,  when carried into the intestine, is attracted by the villous coat,
 or clings to it as if entangled among the villi;  while the excremen-
 titious part, such as bile, is found lying unconnected in the  gut, as
 if separated from the other.*
   The food of animals in  general consists of vegetable or  animal
 substances; and  vegetables seem intended  to  support one class,
 with a view to its being the food of another.   Although there  are
 classes of animals intended to  subsist on  each particular  kind of
 food,  yet  they do not  all  invariably keep to the  same  kind in
 every  stage  of life, many being nourished  by animal  food when
 young that afterwards live on vegetables ; which circumstance will
 be more fully discussed while treating of the first food of pigeons.
   All stomachs do  not equally digest the same substance, although
 it be their natural food.  The caterpillar digests the expressed juice,
 but not the substance; while other animals are capable of dissolving
 nearly the  whole.   Some  animals, as the common  cattle, can feed
 on a variety of vegetables, although  they may have a preference ;
 but there are others that will hardly eat  of more than  one kind.
 Of  this last sort  are  insects in  general, and  the  silkworm will
 scarcely touch anything but mulberry leaves;  but I believe those
 that Jive upon animal food are not so restricted in their choice.
   It is probable that all animal and vegetable substances are equally
 capable of being digested,  if equally soft in their texture; but some
 being  much firmer in that  respect, and others  also  united with in-
 digestible  matter, as the earth  in bones,  more strongly resist  the
 powers of the gastric  juice; therefore mastication  and  trituration
 become necessary to bring them to a similar consistence.  But sub-
 stances may be rendered too soft, for a fluid is difficult of digestion ;
 and we may observe, that  Nature having given us  very few fluids
 as articles of food, to render these few fitter for the action of  the
 digestive powers, a coagulating principle  is provided to give them
 some degree of solidity.f   It is not  easy to assign a reason why
  * [In  chylification, the alkaline principles of  the bile combine with the acids
 which the chyme has received in its formation in the stomach, and the  albumi-
 nous or chylous principles are  developed and attracted by the villi; while  the
 resinous parts of the bile, combined with the excrementitious particles of  the
 chyme, are more or less completely separated.  The most characteristic change
 which, according to Prout, takes place in the intestine is  the  conversion of part
 of the chyme into albumen, which happens even when no albuminous matter was
 originally contained in the food  or formed in the stomach.]
  f The circumstance of the crystalline humour, which is solid, being coagulated
prior to its being digested, renders  it probable that all animal substances go
through that process, and that the loss of texture which they undergo arises
from coagulations
  a [This coagulation happens to all animal substances which contain albumen ;
but can hardly be considered, Dr. Prout observes, "to be essential to the subse-
                                 13* 
138
HUNTER ON THE ANIMAL CECONOMY.
fluidity should be unfavourable to  the  process  of digestion, more
especially as it seems essential to those  of fermentation and chemi-
cal solution.  The requisite  degree of solidity I  should  suppose to
be that of curd, or what is produced by the coagulation ot animal
mucilages, as of the white of an egg.   But this is only supposition,
founded on the idea  that Nature's general principles are right, and
all the corresponding parts  adapted to  one another, except when
monstrous, either in form or action.
   Mastication  is the effect of a mechanical  power, produced by
parts particularly provided for that purpose, which  are of various
kinds,  fitted for that sort of food on which the animal is  by Nature
intended to live, and may be imitated with equal advantage by many
other pieces of mechanism.
  The  masticating  powers are of three  kinds.  The  first is  that
which  merely fits the substance for deglutition, as  in the lion and
many  other  carnivorous animals ; and which, in the  ruminating
tribe, renders the  food fit to be swallowed, that it may undergo such
preparation in the first stomach as is necessary before it is further
masticated for digestion.  The second  is that which not only fits
the food for deglutition, but exposes it to the action  of the gastric
juice, by breaking the shells or husks in which  the  nourishment is
contained, and in which it would be defended  from  the  powers of
digestion.   And the  third is that which  divides and bruises the  food
before  it is received into the stomach.;  which mastication is of  con-
siderable service, by producing a saving in food.*
  The husk of the seeds of plants, although a  vegetable  substance,
appears to be indigestible in its natural  state.   Whether this arises
from the nature of the husk itself, or from  its  compactness, I am
not quite certain, but am inclined to suppose the last, as  we find the
cocoa, which is only a  husk, to be digestible  when ground to a
powder and well boiled.  We know likewise that cuticle, horn,  hair,
and feathers, although  animal substances, are  not  affected, in the
first instance, by the gastric juice; yet if reduced in Papin's digester
to a jelly, that jelly can be acted  upon in the  stomach:  we must
therefore suppose that a certain natural degree of solidity in animal
and  vegetable  substances renders them  indigestible.   This  com-
pactness in the husk seems to be intended to preserve, while under
ground, the farinaceous part of the seed,  in which the  living principle
is placed, the husk  having  probably no other  power of resisting
putrefaction than what  arises  from its texture;  but  whatever  may
be the use of the husk, it  must be  connected with  the  vegetative
process of the  plant.  The  same  purpose of preservation is  pro-
bably answered by  the shells of all ova.   Although  husks are not
capable of being dissolved in the gastric juice, they allow of transu-
dation, and that the seed is in some degree affected by  it is known

quent process; for gelatin, a staminal alimentary principle,  nearly resemblintr
albumen in its composition, undergoes, under similar circumstances, no such
solidifying change.  (Br. Tr., p. 494.)]
  * [Blumenbach has well suggested that the vitality of the  seeds is thus de-
stroyed and they are made subject to the influence of the gastric juice.] 
OBSERVATIONS ON DIGESTION.
139
by its swelling in  the  stomach; yet it can only take up a certain
proportion of it, and that not sufficient to convert it into chyle, the
gastric juice-waving no power of action upon the husks themselves.
Therefore we see  grain of all  kinds, when  swallowed  whole, pass
through entire, though swelled ; and even the kernels of some nuts,
as chestnuts, are not digestible when eaten raw.
  The essential oils of vegetables and animals are indigestible; but
being  soluble either in the  gastric juice  or chyle, they  become
medicinal, from their stimulating powers.  The  essential oil  of
vegetables, but more particularly  that of animals, seems to pervade
the very substance of those animals whose  food contains much of
this oil.   Thus, we find sea-birds, whose constant food is fish, taste
very strongly of fish;  and those who live on that kind of food only
during certain times of the year, as the  wild  duck, have that taste
only at such seasons.   This  fact is  so well  known that  it  was
hardly necessary to put it to the test of an experiment; yet I took
two ducks, and fed one with barley, the other with sprats, for about
a month,  and killed both at the same time :  when they were dressed,
the one fed wholly with sprats was hardly eatable,it tasted so strongly
of fish.
  Although bones are in  part  composed of animal substance, and
so far  digestible, yet  they require stronger powers to digest them
than common meat, from the animal substance  being guarded by
the earth.  Thus,  the animal part of a bone is less easily soluble in
an alkali  than flesh, or than even the animal part when deprived of
its earth by an acid ; nor will a bone, being  guarded by the calcare-
ous earth, submit  to  putrefaction so  readily as  meat; therefore
animals which live upon others, and  swallow them whole  as the
heron, digest bone with more ease  than the crow or  magpie, that are
not accustomed to swallow bones, but commonly pick the flesh only.
  The  degree  of ease  or difficulty  with which  substances are
digested,  will  not  only  arise  from  a  difference  in solidity, but
from a difference in the structure of the parts  themselves; brain,
liver, muscle, and tendon, being  digestible in the  order here put
down.
  There is not only a difference in the degree of facility with which
the various  kinds  of natural  food are digested, but these can also
be made to undergo changes by art, which render  them still more
easy of digestion;  for it appears from  my experiments  that boiled
and roasted,  and even putrid meat, is easier of digestion than raw,
which, in the two first, may  be supposed to arise from  their juices
being  coagulated ; but the same  reason will  not  hold good  with
regard to the putrid.*   A raw egg is  thought  more easy of diges-

  * [From  the various experiments instituted  by Sir Astley Cooper on the diges-
tibility of different substances, it appears that pork is more digestible than mutton,
this than veal, while beef is the least digestible of any.  In feeding dogs with
determinate quantities of each, and  opening them at the expiration of a given
period, it happened that in some instances the pork and mutton had entirely dis-
appeared, while the beef remained but little altered.  Fish and cheese were also
found to be very digestible substances. Potatoes were digestible in a less degree: 
]40          HUNTER ON THE ANIMAL CECONOMY.
 tion than an egg hard boiled, although the raw one must be coagu-
 lated in the stomach before it can  be digested;  and it has likewise
 been observed, that what is easy of digestion is one vtomach will
 not be so  in another; but such cases may probably arise from the
 stomach not being in a healthy state.
   In  many animals the whole of the food does  not  appear  to be
 digested, the substance in part  being found in the faeces ; for if a
 dog is fed with tallow, his excrements will consist of a  somewhat
 firm  unctuous  substance, so  that  the oil is  only digested in part.
 The circumstance of some part of the food, though digestible, not
 being acted upon by the gastric juice, may arise from two causes:
 first, from  many parts of vegetables being too firm in texture to be
 digested in the same time with  the  other food, and being therefore
 carried along in a crude state, together with the chyle, into the
 duodenum; and secondly, from  the stomach  at the  time being so
 much disordered as to digest imperfectly.   We know that food may
 lie a considerable time in the stomach when it is diseased without
 being digested.  Food has been retained in the stomach twenty-four
 hours, and thrown up without being in the least altered, the animal
 at the time not requiring nourishment: this often arises from disease,
 and is also the case with those which go to rest  in the winter.
   The powers of digestion may in  some instances be estimated by
 the appearance  of the excrement, in which, if the food appears not
 to be much altered, we  may conclude that digestion  has had little
 or no  influence on it.  Thus, the excrement of a flea, that has lived
 on blood, is nearly, to appearance, pure blood, not having even lost
 its colour.
  Animals take food in proportion  to the quantity of nourishment
 contained in it, of which the stomach appears, from instinct, to be
 capable of judging;  and also in proportion to  the powers they pos-
 sess of converting what they eat into chyle.  A caterpillar, perhaps,
 eats more in proportion to its size than any other animal that lives
 on the same kind of food ; for not  having the power of  dissolving
 the vegetable, but only of extracting a juice or infusion from it, the
 bit of  leaf  comes  away entire,  coiled up and hardened ; but, by
 being put into water,  unfolds like tea.
  There are few animals that  do not eat flesh in some form or
 other, while there are many who do not eat vegetables at all; and
 therefore the difficulty to  make  the  herbivorous eat meat is not so
 great as to  make the carnivorous eat vegetables.  Where there is
 an instinctive  principle  in an animal, directing it either to  the one
 species of food or the other, the animal will certaintly die rather than
 break  through of its own accord that natural  law ; but  it may be
 made to violate every natural principle bv artificial means.   That
 the hawk tribe can be made to feed upon bread, I have known these
 thirty years; for to a tame kite  I first gave fat, which it ate very
readily;  then  tallow  and butter; and afterwards small  balls of
 Boiled veal was found to be two-thirds more digested than the same meat roasted
 &c.   Muscular tissue, skin, gristle, tendons, bone, were digestible in the order
 here set down.] 
OBSERVATIONS ON DIGESTION.
141
bread rolled in fat or but'ter, and by decreasing the fat gradually,
it at last ate bread alone, and seemed to thrive  as well as when
fed with  meat.   This, however, produced a  difference in the
consistence  of the excrements, for when  it ate meat  they were
thin, and it had the power of throwing them to some distance ; but
when it ate bread they became firmer in texture, and dropped like
excrement of a common fowl.  Spallanzani attempted, in vain, to
make an eagle eat bread by itself; but  by inclosing the  bread" in
meat, so as to deceive the  eagle, the  bread was swallowed, and
digested in the stomach.
  The excrements of animals we may suppose  to  be  that part of
the common food which is indigestible ; and as food is either animal
or vegetable, and each different kind adapted to distinct classes of
animals, it is natural to believe  that the  excrementitious part of
each will be different;  and where the animal feeds upon both,  that
the excrement will be of a mixed nature.  Although this appears
probable, it is only true in a certain degree ; for the mode of diges-
tion, and whether the animal has  a  caecum and colon, with their
peculiar form, have all an influence in the changes which the food
undergoes.  Vegetable food produces more excrement than animal,
and this according to the kind or parts of vegetables that are eaten.
The woody  parts and  husks, which  are  indigestible, produce the
most; the true  farinaceous part the least:  why there should be
any at all from the farinaceous and animal substance, except what
has  eluded  the  action of the  digestive  organs, is not easily ac-
counted for.
  All faeces have a tendency to putrefaction,  but least  in those
animals  which feed on vegetables.  Indeed, the excrement from
vegetable food alone could hardly ever become putrid if it was not
mixed with  the  mucus of the intestines, and would even then be
kept sweet by the tendency which undigested  vegetables have to
take on  the vinous and acetous  fermentation.   But the faeces of
those which live entirely on  animal food in general  very soon
become putrid ;  and indeed often before they are voided ; but such
animals are either without caecum or colon;  or if not, what they
have  is very short; so that the excrement not being long retained,
has less time to become  putrid.   When  the faeces stagnate so as
to take on either the vinous or putrefactive fermentation, air is let
loose, which will be according to the nature of the fermentation ;
most probably, from the vegetable it will be fixed, and from the
animal, inflammable air.
   The faeces of  the greatest number  of animals are tinged by the
bile, which  in  some gives them a yellowish-green colour;  in the
bird they are generally green, but sometimes  white, from being
mixed with the  urine.  The faeces of the maggot appear to be
loaded  with bile;  for  besides  being yellow, they are extremely
bitter, which is  known  by eating the  kernel of a nut that has a
maggot in it.  Some kinds of food, when not wholly digested,  give
a tinge to the faeces, as grass to the excrement of cows. 
142
HUNTER ON THE  ANIMAL CECONOMY.
  The animals which feed  upon vegetables  alone commonly have
their faces somewhat solid; but the degree will  vary according to
the state of the vegetable, whether green  or dried ; and therefore
the particular  state of the faeces will depend on  the nature of  the
indigestible part of the food, and must be different according to the
digestive powers in different  animals.   An animal  that feeds upon
grass has the faeces much  softer than when  fed  on the  same kind
of grass made into hay; and  therefore the faeces of the herbivorous
animals are softer in the summer than the winter; but green  vege-
table food does not produce soft faeces in all  animals, for the cater-
pillar,  which  lives upon  the leaves of vegetables, has  its  faeces
almost dry ; and we find in some ruminating  animals, as  sheep,
that the difference in the faeces during summer and winter is incon-
siderable.   The quadrupeds and birds  that live principally upon
vegetables generally have their caeca large  and the colon long, as
we see  in many of the  ruminating animals.   Some have the colon
both long and large, as the horse and those  of the  rat tribe, which
circumstance  has considerable effects in  allowing the  faeces to
become dry:  in  a few of  the ruminating animals, and of the rat
kind, they are formed into small portions.
   The faeces of quadrupeds living upon animal food are commonly
soft, and in birds are fluid ; but in such as live on both animals and
vegetables, they are in  consistence of a mixed nature, and will be
more or less  soft  according  to the food.   If a  dog is fed entirely
on animal substance its faeces will be soft; if wholly on vegetable as on
bread, they will become so hard as to be  expelled with difficulty.*
  * [The following differences were found  by  Dr. Prout  in the contents of the
rectum of dogs which had been fed on
           Vegetable Food.                       Animal Food.
  Of a firm consistence, and of an olive    Consisted of firm scybala, of a dark
browncolour,incliningtoyellow. Smell  brown colour, inclining to chocolate.
foetid and offensive.  Did not coagulate  Smell very  foetid. Milk was coagulated
milk,                               by the water in  which it  had been dif-
                                   fused.
  A. Water; quantity not ascertained.    A.  Water; quantity not ascertained.
  B. Combination or mixture of altered   B. Combination or mixture of altered
alimentary substances in much greater  alimentary  matters in much greater.ex-
excess than  in the colon,  with some  cess than in either the colon or caecum,
mucus;  insoluble in acetic acid, and  with some  mucus;  insoluble in acetic
constituting the chief bulk of the faeces,  acid, and constituting the chief  bulk of
                                   the faeces.
  C. Albuminous matter, none.          C.  Albuminous matter, none.
  D. Biliary principle, partly changed    D.  Biliary  principle more consider-
to a perfect resin.                    able than in the vegetable faeces, and
                                   almost entirely changed to a perfectly
                                   resinous-like substance.
  E. Vegetable gluten] none; but con-    E.  Vegetable gluten]  nonejbutcon-
tained a principle soluble in acetic acid,  tained a principle soluble in acetic acid,
and precipitable very copiously by oxa-  and precipitable very copiously in oxa-
late of ammonia,                     late of ammonia.
  F. Insoluble  residuum, consisting    F.  Insoluble  residuum, consisting
chiefly of vegetable fibres mixed with  chiefly of hairs.]
haiis. 
                OBSERVATIONS ON DIGESTION.              143

  Spallanzani made  some experiments to prove  that digestion is
carried on after death; but they are not so conducted as to corres-
pond with the appearances met with in the dead body where  that
process has taken place, and the coats of the stomach  itself have
been in  part digested.  An  experiment, although it  may be very
well and accurately made so far as the experiment goes, if a close
connexion is not preserved with the purpose for which it was made,
the conclusions to be drawn from it cannot correspond with the in-
tention.   This is exactly  the case with the experiments of Spallan-
zani, which, although  they prove that meat was digested  in the
stomach after the animal was  killed (which  no one doubted), yet
are not at all  calculated to show that the stomach itself  may be
digested.  In fact, the mode in which they were managed rather
tended to prevent that effect from taking place, for the gastric juice,
by having  substances introduced on which it  could act, was  less
likely to affect the coats of  the stomach.  That the digestion  was
not carried on  merely by the gastric juice secreted  before the
animal  was  apparently dead,  is evident,  from  his  own account,
some of the food which  had  been introduced and digested being
found in the duodenum, a thing that  could not  have happened  if a
cessation of- the actions of life in the  involuntary parts had taken
place when visible life terminated.  There had been  an action, and
most probably a secretion, in the  stomach.  The only experiment
that can be made with any probability of a decided  result, is to kill
the animal while the stomach is empty, and observe what after-
wards takes place.  There are few stomachs that  do  not show,
when examined after death, some of the inner villous coat destroyed,
which may have been done by the gastric juice in the ducts of the
glands which secrete it.
  Dr. Stevens in an inaugural dissertation on this  subject, published
at Edinburgh 1777, gives a number of experiments, some of which
are well devised, to ascertain  the substances  that are easiest of
digestion, a thing in fact more wanted  than the cause of that  pro-
cess: but many of his experiments, more  especially those on rumi-
nating animals, were not made with sufficient accuracy.  How the
chopped hay and potherbs came to be  so much changed in  the first
stomach of a ruminating animal I cannot conceive, as 1 have reason
to believe it has not the least power of digesting, and should doubt
very much that  hay was capable of being wholly digested  in  any
stomach.   His experiment made on  substances out of the body
proves that the gastric juice is not able in all cases to prevent the
vinous and acetous fermentation in vegetables, and  is  a circum-
stance which I believe often  takes place in the living body when the
stomach is weak.  He seems  to be in some apprehension for the
safety of the stopiach itself, from the action of so powerful a solvent
as the gastric juice; but though inclined to suppose that the living
powers of the animal  may guard it against  such effects, yet he is
still disposed to fear that in all cases they may not be sufficient.
   The living  power in the stomach must indeed be very weak to 
144
HUNTER ON THE ANIMAL CECONOMY.
admit of its being digested ; where that  was likely to happen, I
imagine the secretion of the gastric juice would be too defective to
allow of the stomach being acted upon.
  Dr. Stevens gives two cases, with the. dissections, to prove that
the living stomach has not always the power to resist the action of
the gastric juice; but  he  has not made  it clear  that  those very
stomachs might not have been  digested after death.  The appear-
ance of the edges of the hole should have been  more particularly
described;  for if  it took place before death it is  .probable it was
owing to ulceration, which I have sometimes seen.   Men should be
very accurate in ascertaining the truth  of facts before they advance
them, especially when they tend either to overturn a  received opinion
or to establish"a new one.   As to the possibility of animals swal-
lowed alive being digested, no  fresh proofs  are necessary, as we
eat oysters every day;  but this does not prove that they are di-
gested while alive. In his experiments made on ruminating animals
and the  dog, as the vegetables were not so readily digested as the
meat, he concludes, " It is possible  every species of animal has its
peculiar gastric liquor, capable of dissolving certain  substances
only" which is certainly not true.
  Mr. Senebier relates some experiments made by Mr. Gosse upon
himself, but which hardly contain anything except a curious  con-
jecture of Mr. Senebier's, " That distention of the stomach  is the
cause of the secretion of the gastric liquor."  He mentions the sub-
stances, both animal and vegetable, which are not digestible:  then
those difficult of digestion : afterwards, those easily digested ; also
what substances facilitate digestion, and what retard it.  But if we
are to judge of the truth of these facts from a detail of  the experi-
ments which he made to  ascertain them, I am  quite  inclined to
believe that the  experiments  have not been made with sufficient
accuracy to be depended upon.
11.  ON  THE DIGESTION  OF  THE STOMACH  AFTER
                          DEATH.

  The following account of the stomach being digested after death
was drawn up at the desire of the late Sir John Pringle, when he
was President of the Royal Society; and the circumstance which
led to it was  as follows.  I had opened, in his presence, the  body
of a patient who had been  under his  care, in which  the stomach
was found to be in part dissolved ; a thing  that appeared to him
very accountable, there  having been no previous  symptom which
could have led him to suspect any disease in the stomach.  I took
that  opportunity of explaining to  him  my ideas respecting  it; and
that, having long been employed in making experiments on digestion,
I had been induced to consider this as one of the facts which proved
a converting power in the gastric juice.  I mentioned my intention 
         DIGESTION OF THE STOMACH AFTER DEATH.      145

of publishing the whole of my observations on digestion at some
future period; but he desired me, in the meantime, to give this fact
by itself, with my remarks; as it  would prove  that there is a sol-
vent power existing in the stomach, and would be of use in the ex-
amination of dead bodies.*
  An accurate knowledge  of the appearances in  animal  bodies,
where death has been  the consequence of some violence while they
were otherwise in health, ought certainly to be considered as neces-
sary to  qualify us to judge truly of the state of the body in those
that  die of  diseases.   An animal  body undergoes changes after
death;  but it has never  been sufficiently considered what those
changes are, or how soon they may take place ; yet till this be done
it is impossible we  can form an accurate judgment of the appear-
ances which present  themselves  at the time of inspection.  The
diseases of an  animal body (mortification excepted)  are  always
connected with the living principle, and are not in the least  similar
to the  changes which take  place in  the dead body: without  a
knowledge of this, an opinion drawn from dissections must  always
be very imperfect or very erroneous.   Appearances  which are in
themselves natural may be mistaken for those of disease ; we may
see diseased parts, and suppose them in a natural  state; we may
consider a circumstance to have  existed before death which was
really a consequence of it; or we may imagine it to be a  natural
change after death, when it  was in fact a disease of the living
body.  It is easy to see, therefore, how a man in this state of igno-
rance must  blunder when he comes to connect the appearances in
a dead  body with the  symptoms that were  observed in life; and,
indeed, all the advantage to be derived  from  opening dead bodies
depends upon  the  judgment  and  sagacity  with which this sort of
comparison is made.
  There is a case of a mixed nature, which can neither be reckoned
a process of the living body nor of the dead : it participates of both,
inasmuch as its cause  arises from life, and the  effect cannot take
place till  after  death.   To render this more intelligible, it  will be
necessary to state  some general ideas concerning this cause and
effect.
  An animal substance, when joined with the living principle, can-
not undergo any change  in  its properties but  as an animal;  this
principle always acting and  preserving the substance possessed of
it from dissolution, and  from being  changed according  to the
natural changes which other substances undergo.

  * [The original paper is  printed in the 62d volume of the Philosophical Trans-
actions;  and was read June 18th, 1772.  It begins as follows: "An  accurate
knowledge of the appearances in animal bodies that die of a violent death, that
is, in'perfect health, or in a sound state, ought to be considered as a necessary
foundation forjudging of the state of the body in those that are diseased."  The
remainder of the essay is given in the 2d edition of the Animal CEconomy, with
verbal alterations of the same kind and degree as are exemplified in the paragraph
above quoted ; with the omission of one sentence and a note, which are subjoined
at the end of the paper.]
                               14 
146          HUNTER ON THE ANIMAL CECONOMY.

  There are a great many powers in nature which the living prin-
ciple does not enable the animal matter, with which it is combined,
to resist, viz., the mechanical and most  of the strongest chemical
solvents.  It renders it, however, capable of resisting the powers
of fermentation, digestion, (and perhaps several others,) which are
well known to act on this same matter, and entirely to decompose
it, when deprived of the living principle.  The number of powers
which thus act differently on the living and dead animal substance
not  being ascertained, we shall only take  notice of two, putrefac-
tion and digestion, which do not affect this substance, unless when
it is deprived of the living principle.  Putrefaction is an effect which
arises spontaneously; digestion is an effect of another principle,
and shall here be  considered  a little more particularly.
  Animals, or  parts  of animals, possessed  of  the  living  principle,
when  taken into  the stomach, are not in the least affected by the
powers  of that viscus so long as  the  animal principle remains.
Hence it is that we find animals of various kinds not only can live
in the  stomach, but are  even hatched  and bred there; yet the
moment that  any of these lose the  living  principle, they become
subject to the digestive powers of the stomach. If it were possible
for a man's hand, for example, to be introduced into the  stomach
of a living animal, and kept  there for some considerable time, it
would be found  that the  dissolvent powers of the stomach could
have no effect  upon it; but if the same hand were separated  from
the body, and introduced into the same stomach, we should then
find that the stomach could immediately  act upon it.   Indeed, if
the first were not the case, the stomach itself ought to have been
made  of indigestible  materials;  for were  not the living principle
capable  of preserving animal substances  from  being acted upon by
the process of digestion, the stomach itself  would be digested ; and
accordingly we find that the stomach, which at one instant, that is,
while possessed of the living  principle, was capable of resisting the
digestive powers which it contained, the next moment, viz., when
deprived of the living principle, is itself capable of being digested,
not  only by the digestive  powers  of other stomachs, but even by
the remains of that power which itself had of digesting other things.
  These observations lead us to account for an appearance which
we often find in the stomachs of dead bodies ;  and they at the same
time throw considerable light upon  the nature of  digestion.  The
appearance we allude to is a dissolution of the stomach at its great
extremity, in consequence of which there is frequently a considera-
ble  aperture made  in  that  viscus.   The  edges  of this opening
appear to be half dissolved, very much  like that  kind of solution
which fleshy parts undergo when half digested in a living stomach,
or when  acted  upon by  a caustic alkali, viz., pulpy, tender and
ragged.
  In these cases the contents of the stomach are generally found
loose in the cavity of the abdomen, about the spleen and diaphragm ;
and in many subjects the influence of this digestive power extends , 
         DIGESTION OF THE STOMACH AFTER DEATH.       147

much further than through the stomach.  I have often  found that,
after the stomach had been dissolved at the usual place, its contents
let loose had come into contact with the spleen and diaphragm, had
dissolved the diaphragm quite through, and had partly affected the
adjacent side of the spleen, so that what had  been contained in the
stomach was  found  in the  cavity of the thorax, and had  even
affected the lungs to  a small degree.
  There are very few dead bodies in which the stomach at its great
end is not in some degree  digested;  and one  who is acquainted
with dissections can  easily trace these gradations.  To be sensible
of this effect nothing more is necessary than  to compare the inner
surface of the great end of the stomach with  any other part of its
inner surface: the sound portions will  appear  soft, spongy,  and
granulated, and  without distinct  blood-vessels, opake  and  thick;
while the others will appear  smooth, thin, and more transparent;
and the vessels will be seen ramifying in its substance, and upon
squeezing the blood which they contain from  the larger  branches
to the smaller, it will be found to pass out at the digested ends of
the vessels, and to appear like drops on the inner surface.
   Though I have often seen such  appearances, and supposed that
they must  have been seen  by others, yet I was quite at  a loss to
account for them.  At first I  supposed them to  have been produced
during life, and was  therefore inclined to look  upon them as  the
cause of death, only that I never  found  they had  any connexion
with the patient's  symptoms; but  I was still  more  at a loss to
account for them when I discovered  they were most frequent in
those who  died by sudden  violence;  a circumstance which made
me suspect that the true cause was not guessed  at.*  At  this time
I was employed in making experiments upon digestion  in  different
animals, all of which were killed  at  different  times, after having
been  fed with  various kinds of food :  many of these  were not
opened immediately  after  death, and  in some  of them I found the
above-described appearances in the stomach.    The better to pursue
my inquiry on the  subject of digestion, I procured the stomachs of
a vast variety  of fishes, whose deaths are always violent, and who
may be said to die in perfect health, with their stomachs usually

  * The first time that I bad occasion to observe this  appearance where death
had been produced by violence, and where it could not  therefore easily be sup-
posed to be the effect of disease, was  in a man who had his skull fractured by
one blow of a poker.  Just before this accident he had been in perfect health, and
had taken a hearty supper of cold meat, cheese, bread, and ale.  Upon opening
the abdomen, I found that the stomach, though it still contained a good deal, was
dissolved at  its great end, and a considerable part of its contents lay loose in the
general cavity of the belly ; a circumstance which puzzled me very much.  The
second instance was  in a man who died at St. George's Hospital, a few hours
after receiving a blow on his head which fractured his skull.  From  these two
cases, among various conjectures about so strange an appearance, I began to sus-
pect it  might be peculiar to cases of fractured skull, and therefore, whenever  I
had an opportunity, I examined the stomach of every person who died from that
accident; but I found many of them which had not this appearance. I afterwards
met with the same appearance in a man who had been hanged. 
148
HUNTER ON THE ANIMAL CECONOMY.
full.   In them we can observe the progress of digestion  most  dis-
tinctly, the shape of their stomachs being very favourable for  that
purpose.  They likewise swallow their food whole, that is, without
mastication,and swallow fish that are much larger than the digesting
part of the stomach can contain ; therefore in many instances the
part swallowed which was lodged in the digesting part of the sto-
mach was found more or less  dissolved, while that which remained
in the oesophagus was perfectly sound ; and in many of these I saw
the digesting part of the stomach itself reduced  to the  same dis-
solved state as the  digested part of the food.
   Being  employed upon this subject, and  therefore  enabled  to
account more readily for appearances  which  had  any  connexion
with it, and observing that the half-dissolved  parts of the stomach
were similar to the half-digested food, it  immediately  struck me
that it was the process of digestion going on after death; and that
the stomach, being dead, was no longer capable  of resisting the
powers of that menstruum which itself had formed for the digestion
of food.*                            ,
   These appearances of the stomach after death throw considerable
light on the principles of digestion, and show that it neither depends
on a mechanical power, nor  contractions of the  stomach, nor on
heat, but something secreted in the coats of the stomach, and thrown
into its cavity, which there animalizes the food, or  assimilates it to
the nature of  the blood.f  The power of the gastric juice  is  con-
fined or limited to certain substances, generally of the  vegetable
and  animal kingdoms ; and although this menstruum is capable of
acting independently of the stomach, yet it is  indebted to that viscus
for its  existence and continuance.

   * [Then follows in the original paper:
   " With this idea, I set about making experiments to produce these appearances
at pleasure, which would have taught us how long the animal ought to live after
feeding, and how long it should remain after death before it is opened ; and above
all, to find out the method of producing the greatest digestive power in the living
stomach: but this pursuit led me into an unbounded field."—Phil.  Trans. (1772),
p. 453.]
   \ [In the original paper the following note here occurs: " In all the animals,
whether carnivorous or not, upon which I  made observations or  experiments to
discover whether or not there was  an acid in the stomach (and I tried this in a
great variety), I constantly found that there was an acid, but not a strong one, in
the juices contained in that viscus  in a  natural  state."  The omission of this
note both in the 1st and 2d editions of the Animal  CEconomy was probably a
consequence  of the doubt subsequently entertained  by  Hunter of the natural
presence of an acid in the gastric juice; but as the existence of hydrochloric acid
as an essential constituent of the animalizing secretion of the stomach is now
satisfactorily determined, we have thought it proper to restore this record of the
agreement of a great proportion of Hunter's experience with that of late observers
on this subject.] 
SECRETION IN THE CROP OF BREEDING PIGEONS.     149
12. ON  A  SECRETION  IN  THE  CROP  OF BREEDING
      PIGEONS, FOR THE  NOURISHMENT OF  THEIR
      YOUNG.

  The nourishment of animals admits, perhaps, of as much variety
in the mode by which it is to  be performed  as any circumstance
connected with their ceconomy, whether we consider their numerous
tribes, the different stages through which every animal  passes, or
the food  adapted  to the support of each in their distinct conditions
and situations.  We are likewise to include in this view that endless
variety in the means by which this food is  procured, according to
the class of the animal  and  the  particular stage of its  existence.
If the food was the same through every period of the life of an animal;
if every  individual of a tribe lived on the same kind, and procured
it by the  same mode, our speculations would then admit of a regular
arrangement.  But when we see that the food adapted to one stage
of an animal's life is rejected  at another, and that  animals  of  one
class in some respects  resemble those of another, by hardly  having
any food peculiar to themselves, the subject becomes so complicated
that it is not surprising if we are at a loss to arrange  the various
modes by which  animals are nourished.
   Animal life may not improperly be  divided into three states or
stages.   The first comprehends the production of the  animal  and
its  growth  in the foetal  state; the  second commences when it
emerges from that state by what is called the birth, yet for a  certain
time must, either mediately  or immediately, depend  on  the  parent
for support;  the third may be said to take place when the  animal
is fit and at liberty to act for itself.  The first and third stages are
perhaps  common to  all animals; but  there are some classes, as
fishes,  spiders, &c, which seem  to have  no  second stage,  but
pass directly from the first to what is the  third  in  other animals.
Of those requiring a second stage, the polypus and  the viviparous
animals  continue to  derive their nourishment  immediately from
the parent: while the  oviparous are  for some time supported by
a  substance originally formed  with them, and  reserved for that
purpose.*
   There is  infinite variety in the means by which Nature provides

  * [The species of  polypus to which Mr. Hunter here refers is most probably
the freshwater gemmiparous hydra;  but the  period during which  the young
polype is  growing at the expense of the parent seems rather to correspond to the
first or foetal stage of existence than the second : when, again, the communication
with the digestive sac of the parent is obliterated,  the young polype derives its
nourishment from without by the exercise of its tentacles, until it is finally cast
off.  The viviparous animals are the Mammalia, and the nourishment alluded to
is the lacteal secretion.  The nutritious substance with which the oviparous
animals continue for a short period to be supported after their exclusion from
the egg is the yolk,  which has then passed into the abdomen, where it is finally
absorbed.]
                               14* 
150          HUNTER ON THE ANIMAL CECONOMY.
for the support of the  young in the second  stage of animal life.
In many insects it is effected by the female instinctively depositing
the egg, or whatever contains the rudiments of the animal, in such
a  situation that, when hatched, it may be within reach of  proper
food; others, as thc!humble-bee and black-beetle * [Blattay collect a
quantity of peculiar substance, which both serves as a  nidus for
the egg, and nourishment for the maggot, when the embryo arrives
at that state.   Most birds, and many of the bee-tribe, collect food
for their young; when at a more advanced period the task of feed-
ing them is performed by both male and female, with an exception
in the common bee, the young ones of which are  not fed  by either
parent, but by the working-bees, which act the part of the  nurse.
There is likewise a  number of animals capable of supplying im-
mediately from their  own  bodies the nourishment proper for their
offspring during this  second stage, a  mode of nourishment which
has hitherto been  supposed to be peculiar to  that class of animals
which Linnaeus calls Mammalia;  nor has it, I imagine, been ever
suspected to belong to any other.
  1 have, however, in my inquiries concerning the various  mpdes
in which young animals are  nourished, discovered that all of the
dove kind are endowed with a similar power.  The young pigeon,
like the young quadruped, till it is capable of digesting the common
food of its kind, is fed with a substance secreted for that purpose
by the parent  animal; not, as  in the  Mammalia, by the  female
alone, but also by  the male, which, perhaps, furnishes this nutriment
in a degree still more abundant.  It is a common property of birds,
that both male and female  are equally employed  in hatching, and
in feeding their young in  the second  stage; but  this  particular
mode  of nourishment, by means of a substance  secreted in their
own bodies, is  peculiar to  certain kinds, and  is carried on in the
crop.
  Besides the dove kind, I have  some  reason to suppose parrots
to be endowed with the same faculty, as they have the power of
throwing up the contents of the crop, and  feeding one another.   I
have seen the cock parroquet regularly feed the hen, by first filling
his own crop, and then supplying  her from  his beak.  Parrots,
maccaws, cockatoos, &c, when they are very fond of the person
who feeds them, may likewise be  observed to have the action of
throwing up the food, and often do it.  The cock pigeon, when he
caresses the hen,  performs the same kind of action as  when  he
feeds  his young;  but I do not known if at this time he throws up
anything from the crop.
  During incubation the coats of the crop in the pigeon are gradually
enlarged and thickened, like what happens to the udder of females
of the class Mammalia in the term of uterine gestation.  On com-
paring the state of the crop when the bird is not sitting, with its
appearance during incubation, the difference  is  very remarkable.
In the first case it is  thin  and membranous; but by the time the
young are about to be hatched, the whole, except what lies on the 
ON THE GILLAROO-TROUT.
151
trachea, becomes thicker, and  takes  on a glandular appearance,
having its internal surface very irregular.  It is likewise evidently
more vascular than in its former state, that it may convey a quantity
of blood sufficient for the secretion of the substance which  is to
nourish the young brood for  some days after  they are hatched.
  Whatever may be the consistence of this substance when just
secreted, it most  probably very soon coagulates into a granulated
white curd, for in such form I have always found it in  the crop ;
and if an old pigeon is killed just as the young ones are hatching,
the crop will be found as above described, and  in its cavity pieces
of white curd, mixed with some of the common food of the pigeon,
such as  barley, beans, &c.  If we  allow either of the parents to
feed  the brood, the crop of the young pigeons when examined will
be discovered to contain the same  kind of curdled substance as that
of the old ones, which passes from thence into  the stomach, where
it is  to be digested.
  The  young pigeon is fed for a little time with this  substance
only, as  about the third day  some of  the common food is found
mingled with it:  as the pigeon grows older the proportion of com-
mon food is increased ; so that by the time it is seven, eight, or
nine days old, the secretion of the curd ceases  in the old ones, and
of course no more will be found in the crop of  the  young.  It is a
curious fact that the parent  pigeon has  at first a power to throw
up this curd without any mixture of common food, although  after-
wards both are thrown up according to the proportion required for
the young ones.
  I have called this substance  curd, not  as  being literally so, but
as resembling that more than  anything I know; it may, however,
have a greater resemblance  to curd than we  are perhaps aware of,
for neither this secretion, nor curd from which the whey has been
pressed, seems to contain any sugar, and do not run into the acetous
fermentation.  The property of coagulating  is confined to the sub-
stance itself, as it produces no such effect when mixed with milk.
   This secretion in  the pigeon, like  all other animal substances,
becomes putrid by standing, though not so readily as  either  blood
or meat, it resisting putrefaction for  a  considerable time; neither
will curd much pressed become putrid so soon as  either blood or
 meat.
13  OBSERVATIONS  ON THE GILLAROO-TROUT. COM-
      MONLY  CALLED IN IRELAND  THE  GIZZARD-
      TROUT.*

  OiVE of the digestive organs of the  gillaroo-trout being  so very
remarkable as to have given name to the fish, and to have been
considered as its distinguishing characteristic, it is my intention to
  *  [Originally published in  the Philosophical Transactions, vol. lxiv. (1774.)] 
152
HUNTER ON THE ANIMAL  CECONOMY.
inquire whether its resemblance to a gizzard be sufficiently strong
to render the term of gizzard-trout a proper appellation, and what
place its stomach ought to hold among  the  corresponding  organs
of other animals.   For this  purpose  it will  be  necessary to state
certain facts connected with the subject, and take a general view
of the varieties which  occur in the  digestive organs in different
animals.
   The food of animals may be divided into  two kinds, what does,
and what does not, require mastication to facilitate digestion.  The
flesh of animals is of the latter kind; but grain, and many other
substances  which  serve for aliment, require a previous grinding or
trituration, and therefore animals living  on  this kind  of food are
furnished with organs for that purpose.   Granivorous quadrupeds
have the two powers, for mastication and  digestion, separate or
distinct from  one  another; the first being executed by teeth, which
serve as so  many grindstones for reducing their food to smaller
parts, before  it is  conveyed into the stomach for digestion;  but the
form of these teeth varies  very considerably in different animals,
although the  food be the same.  This grinding also fits it for deglu-
tition ; for  neither grain nor herbs  could be  swallowed without
having first been  masticated.  When so prepared, it is, with regard
to the digestive power, rendered similar  to animal food; therefore
in many of  the  granivorous the stomach  resembles that of the
carnivorous animals ; and whenever  the stomach in the granivorous
quadruped  departs from this general  rule, there is a peculiarity  in
the operations of  digestion.   Birds that live upon substances, for the
digestion of which trituration is  indispensably necessary, have the
powers of mastication and digestion  united in one part, the gizzard,
which is  particularly  constructed for  that purpose, but is more
uniform in  its construction  than the  teeth,  varying only by being
stronger or weaker in its powers; therefore  the genius of  birds
exhibits less variety, respecting the organs relating to digestion,  than
the quadruped.   In granivorous  birds, therefore,  one  single organ
answers both to the teeth and stomach of granivorous quadrupeds,
and consequently the gizzard alone of birds will as clearly point out
the food of the species  as both teeth and stomach together, in those
animals in which the two offices of  mastication  and digestion are
not performed together in the same part.
   As it appears to be the difference of stomachs only that fits birds
for their different kinds of food, as there  is little difference in con-
struction, excepting only in strength ;  and as the food of the different
species is of every kind, from the hardest grain to  the softest animal
matter, we may conclude that every  gradation  of the stomach is to
be found among them,  from the true  gizzard, which  is one extreme,
to the mere membranous stomach, which is the other.  In conse-
quence of this, it  must be as difficult  to determine the exact limits
of the two different modes of construction to which the names  of
gizzard and  stomach specifically belong, as, in any other case, to
distinguish proximate steps in the slow and imperceptible gradations
of Nature. 
ON THE GILLAROO-TROUT.
153
  The two extremes of true gizzard and membranous stomach are
easily defined ; but they run so into each other, that the end of one
and the beginning of the other is quite imperceptible.   Similar gra-
dations are observable in the food : the kinds suited to the two ex-
tremes mixing together  in  different proportions  adapted to the in-
termediate states of stomach.
  A true gizzard is composed of two strong muscles, placed opposite
and acting upon each other,  like two  broad grindstones.   These
muscles are joined together at their  sides by a middle tendon, into
which the muscular fibres  are  inserted, and which forms the nar-
row anterior and posterior sides of the flat  quadrangular cavity in
which the grinding is performed.  The upper end of this cavity is
occupied by the termination of the oesophagus, and the beginning of
the intestine.  The lower end consists of a  thin  muscular bag con-
necting the edges of the two muscles together.
   By these two more soft  and flexible substances being thus inter-
posed  between the two strong grinding muscles a double advantage
is gained; for whilst one gives an easy  passage to the oesophagus
and gut, when both  act together they serve in  some degree as a
hinge, on which the two muscles may be said to move, by the mid-
dle tendon allowing of a free motion of the grinding surfaces on each
other, which is necessary for the comminution of food.
   The two flat lateral sides of the grinding cavity are lined with a
thick horny substance,  similar to a hard and thick cuticle;  the nar-
row anterior and posterior tendinous parts are also lined with a cu-
ticle,  but not so strong as the former; this  horny substance is gra-
dually lost at one end in a very thin cuticle, which lines the passages
of the oesophagus and intestine for a little way, and at the other end
 is lost in the same manner in  the membranous bag.
   The two large muscles may be considered as a pair of jaws, whose
 teeth are occasionally supplied, being small rough stones or pebbles
 which the animal swallows, which  from the feeling of the tongue
 can distinguish such as are proper from those  which  are not, in-
 stantly dropping out of its mouth such as are smooth  and otherwise
 unfit for the purpose.
   Some birds with gizzards have also a craw or crop, which  serves
 as a reservoir, and for softening the grain; but  as all of them have
 not this organ it is not to  oUr present purpose.
   There are other animals, besides this class of birds, which mas-
 ticate their  food  in the stomach ;  but  teeth are placed there by
 Nature ; of this kind are crabs and lobsters.
   The gradation from gizzard to stomach is made by the muscular
 sides becoming weaker and weaker, and  the food keeps pace with
 this chance, varying gradually from vegetable to animal.*   In one
 point of view,  therefore, food may be considered as a first principle,
 with respect to which  the digestive organs with their appendages

   * TThe o-izzards of birds which live on hard-coated coleopterous insects are
 stronger than  those which have to digest soft pulpy fruits.] 
154
HUNTER ON THE ANIMAL CECONOMY.
act as but secondary parts, being adapted to and determined by the
food as the primary object.
  We find then that in all granivorous animals there is  an appa-
ratus for the mastication of the food, although often differing in con-
struction and situation;  but  in true carnivorous animals, of what-
ever tribe, mastication not being  so  necessary, they have no appa-
ratus for that purpose.   The teeth of such quadrupeds as are carni-
vorous serve chiefly to procure food and  prepare it for deglutition;
the same thing is performed  in the true carnivorous  birds by their
beak and talons, whose office it is to procure the  aliment and fit it
for deglutition, corresponding in this respect with the teeth of the
others.   Applying this reasoning  to fish,  it  seems, at first sight, as
if there were no occasion in them for that variety of structure in the
digestive organs as is found in the before-mentioned quadrupeds and
birds, the food of fish being principally of one sort, namely animal;
which, however, with regard to  the digestive  powers, is to be dis-
tinguished into  two kinds, viz., common  soft and shell-fish.  Such
fish as live on the first  kind  have, like the carnivorous quadrupeds
and  birds, no apparatus for  mastication,  their  teeth being intended
merely for catching the food and fitting  it to be swallowed.  But
the shells of the  second kind of food render some degree of masti-
cating power necessary to fit it  for its passage either into  the sto-
mach or through the intestines; and accordingly we  find in certain
fish a structure suited to the purpose.
  Thus the mouth of the wolf-fish is almost paved  with teeth, by
means of which  it can break shells to  pieces  and fit them for the
oesophagus of the fish,  and so effectually disengage the food from
them, that though it lives upon such hard  food, the stomach does not
differ from that of other fish; the organs of mastication and digestion,
therefore, in this animal, exactly  correspond to those of many gra-
nivorous quadrupeds.
  Other fish, on  the contrary,  approach  nearer to the structure of
birds by  having  their stomach furnished  to a certain degree with a
masticating power, which in many is very imperfect compared with
the gizzards of fowls.   Perhaps the difference is only what the dif-
ference of food will properly allow ; as in fish which have this power,
the food  being still animal, and in general  but imperfectly  covered
with the  shell, it probably requires only to be broken, perhaps hardly
that, for  the mere purposes of digestion,  as food is  digested when
introduced into the stomach in silver balls with  only  a few small
holes, but it may be necessary to fit the shells for passing along the
intestines after the fish is digested.  In the Bulla lignaria of Linnaeus
this apparatus is more perfect, consisting of two bones, which we
must suppose capable of grinding hard shells ; but the food of gra-
nivorous birds requires to be ground into a kind of meal.
   Of all  the fish  I have seen, the mullet is the most  complete instance
of this  structure,  its  strong  muscular  stomach being evidently
adapted, like the gizzard of birds, to the  two offices  of mastication
and digestion.   The stomach of the fish now before us holds the
second place. 
ON ANIMALS PRODUCING HEAT.
155
   But still neither of these stomachs can be justly ranked as gizzards,
since they want some of the most essential characters, viz., a power
and motion fitted for grinding, and the horny cuticle.*  The stomach
of the gillaroo-trout  is, however, more globular  than  that of most
fish, better adapted for small food, and endued with sufficient strength
to break the shells of small shell-fish;  which will probably be best
done  by having more than one in the stomach at a time, and also by
taking pretty large and smooth stones  into the stomach, which will
answer the purpose of breaking, but not so well that of grinding, nor
will they hurt the stomach,  as  they are  smooth,  when swallowed;
but this stomach can scarcely  possess any power  of grinding, as
the whole cavity is lined with a  fine  villous coat, the internal surface
of which appears everywhere to  be digestive, and  by no  means
fitted for mastication.
   The stomach of the common stream-trout is exactly of the same
structure with that of the gillaroo ;  but its coat not so thick by two
thirds, f   How far this difference  in  thickness of stomach is suffi-
cient to form a distinct species, or barely a variety of the same, is
only  to be determined by experiment.J
   The oesophagus in  the trout is considerably longer and smaller
than  in many other classes of fish.
   The intesines are similar to those of the salmon, herring, sprat, &c.
   The pancreas is appendiculated.
   The teeth show them to be fish of prey.
   So far as  we are led to determine by analogy,  we must not con-
sider the stomach of this  fish as a gizzard, but as a  true stomach.
14. EXPERIMENTS AND OBSERVATIONS ON ANIMALS,
      WITH RESPECT  TO THE POWER OF PRODUCING
      HEAT.§

   Some late  ingenious experiments and observations,  published in
the Philosophical Transactions,!!  upon a power which animals seem

  * [We have examined the gizzard of the mullet (Mugil Capito, Cuv.), and find
that it is lined by a distinct layer of rough and  easily separable cuticle.]
  f The common stream-trout swallows shell-fish, and also pretty large smooth
stones, which serve as a kind of shell-breakers.
  X Viz., take some gillaroo-trout, male and female, and put them into water in
which there are no trout, to see if they  continue the same.1
  § [This Essay includes the greater part of two papers, one published with the
title ' Experiments on Animals and Vegetables, with respect to the Power of pro-
ducing Heat,' in the Philosophical Transactions, vol. lxv. (read June 22,1775);
the other, 'On the Heat, &c, of Animals and  Vegetables,' in the Philosophical
Transactions, vol. lxviii. (read Juno 19, and Nov. 13, 1777.)]
   || [' Experiments and Observations in  a heated Room,' by Charles Blagden,
M.D., F.R.S., vol. Ixv., p. 111.]

  a [They are considered to be varieties of the Salmo  Fario, Linn., by the best
modern naturalists: see Yarrell's * British Fishes,' vol. ii., p. 57.] 
156          HUNTER ON THE  ANIMAL CECONOMY.
to possess of generating cold,  induced me to  look  over my notes,
containing some which I had made in the year 1766, indicating an
opposite power in animals,  whereby  they are capable  of resisting
any external cold while alive,  by generating  wiihin themselves  a
degree of heat sufficient to counteract it.   Those experiments were
not originally instituted with any expectation of the event which re-
sulted from them, but for the purpose of satisfying  myself whether
an animal could retain life after being frozen, as has been confidently
asserted both of fishes and snakes.  For that these, after being frozen,
still  retain so  much of life as when thawed  to resume their vital
actions, is a fact so well attested that we are bound to believe it;
and had my experiment succeeded, it was my intention to have tried
the effects of freezing on living animals to a much greater degree
than can ever happen  accidentally.
   I mention these circumstances to account for what might other-
wise be attributed to negligence and inattention,  namely, the little
nicety that was observed  in measuring the precise degree of cold
applied in the experiments.   Accuracy in this particular was not
aimed at, being of no consequence in the inquiry more  immediately
before me.  The cold was first produced by means  of ice and snow
with sal ammoniac or sea-salt, to about the 10° of Fahrenheit's ther-
mometer : ice was then mixed with spirit of nitre; but  what degree
of cold was thus produced I did not examine.  This cold  mixture
was made in a tub  surrounded with woollen  cloths, and  covered
with the same, to prevent the effects of the heat of the atmosphere
upon the mixture itself, and to preserve, as much as possible, a cold
atmosphere within the vessel.  Animal juices, as the blood, freeze
at 25°, so that a piece of dead flesh could be frozen in an atmosphere
cooled to that point.

                         EXPERIMENTS.

   Experiment  I. was made on two carp.  These were put into a
glass vessel with common  river water, which was placed  in the
freezing mixture.  The water not freezing fast  enough, to  hasten
that effect as much cooled snow was added as to render the whole
thick.  The snow round the carp melting, we put in more fresh snow,
which, melting also, was repeated several times, till we grew tired,
 and at last left them covered  up in  the  yard to freeze by the joint
 operation of the surrounding mixture and the natural cold of the at-
 mosphere.*  They were  frozen at last, after having exhausted the
 whole powers of life in the production of heat.   That this was really
 the case, could not be known till I had completed that part of the
 experiment for which the whole was begun, viz., the thawing of the

   * [This experiment is alluded to by Dr. Blagden, who observes, "The power
  of generating heat seems to attend life very universally.  Not to mention other
  well-known experiments, Mr. Hunter found a carp preserve  a coat of fluid water
  round him long after all the rest of the water in the vessel had been congealed by
  a very strong freezing mixture."—Phil. Trans., lxv.,  p. 122.] 
ON ANIMALS PRODUCING HEAT.
157
animals.  It  was done very gradually ; but the animals did not,
with flexibility, recover life; and while in this cold, showed signs of
great uneasiness by their violent motions.  MB. In some of these
experiments,  where air was made the conductor  of the cold and
heat, that the heat might be more readily carried off from the animal,
a leaden vessel was used.  It was small for the same reason ; and as
it was  necessary for the animal's respiration that the mouth of the
vessel should communicate with the open air, it was made deep, that
the cold of the atmosphere round the animal might not be diminished
too quickly by the warmth of the open air, which would have spoiled
it as a conductor.
  Experiment II. was  upon a dormouse,  the vessel in which it was
confined being sunk in the cold mixture almost to its edge.   The
atmosphere round  the  animal  soon cooled ;  its  breath  froze as it
came from the mouth ; a hoar-frost gathered on its whiskers, and on
all the inside of the vessel, and the external points of the hair be-
came covered with the same.   While this was going on the animal
showed signs of great uneasiness ; sometimes it would coil itself into
a round form, to  preserve  its  extremities and confine its heat; and
finding that ineffectual, would  then endeavour to make its escape.*
Its  motions became less violent by the sinking of the vital powers :
its feet were  at last frozen : but we were not able to  keep up the
cold a sufficient time to freeze  the whole animal, the hair being so
bad a conductor of heat that  the consumption was not more than
the animal powers were capable of supporting-!
  Experiment III.  was made with another  dormouse;  and  taught
by  the  failure of the  last  experiment, I took  care  that  the hair
should not a second time be an obstruction to our success.  Having,
therefore, first made the animal wet all over, that its  heat might
be more rapidly carried off, it was put into a leaden vessel, and the
whole  placed in the cold mixture as before.   The animal soon gave
signs of feeling the cold, by repeated attempts to make its escape;
and the breath and water evaporating from its body being soon frozen,
appeared  like a hoar-frost on the sides of the vessel and on its whis-
kers ; but while the vigour of life lasted it defied the approach of the
cold.   However, from the hair being wet, and thereby rendered a
good conductor, there was a much greater consumption of heat than
in the former experiment, which hastened on the diminution  of the
power of producing it. The animal dying, soon became stiff, and,
upon being thawed, was found quite dead.
   Experiment IV.  A  toad being  put into a vessel with water, at
such a depth as not to cover its mouth, was  placed in the mixture

  * This shows that cold  carried to a great degree  rather rouses than depresses
the animal action ; but it appears, from many circumstances and observations,
that a certain degree  of cold produces inactivity both in living and sensative
principle, which will be further illustrated hereafter.
  f These  experiments were made  in presence of Dr. George Fordyce  and Dr.
Erwin, teacher of Chemistry at Glasgow, the latter of whom came in accidentally
in the middle of our operations.
                               15 
158
HUNTER ON THE ANIMAL CECONOMY.
cooled to between 10° and 15°.  The water froze so  near to the
body of the animal as quite to inclose  it,  but without destroying
life; yet, though  not  frozen, it hardly ever recovered the  use of
its limbs.
  Experiment V. was with a snail, which froze very soon, in a cold
between 10° and 13°.  These two last experiments were  made in
the winter, when the living powers of the animals selected for the
trial are very weak; they might have resisted the cold more strong-
ly in the summer.   Why the  animals mentioned in the above ex-
periments  died before they were frozen, while those which are
exposed to the atmosphere in very cold climates do not, is a point I
shall not pretend to determine,  not knowing the difference  between
the effects of a natural and an artificial cold.  It may be accounted
for by supposing that  the natural cold in climates in which animals
are found frozen is so intense as to produce congelation immediately,
before the powers of  life are exhausted; at  least whether it is so or
not is worthy of inquiry.
  It appears from the above experiments, first, That most proba-
bly the animals were deprived  of  life before they were  frozen;
secondly, That there was an exertion or expense of animal power in
resisting the effects of cold, proportioned to the necessity;  thirdly,
That  this exertion was in  proportion  to the  perfection of the animal
and the natural heat proper to each species and to each age.  This
exertion might also perhaps depend in some degree on other cir-
cumstances not hitherto observed; for from  Experiments II. and III.
upon  dormice, I find that in the animals which are of a constitution to
retain nearly the same heat in all temperatures of the air, it required
the greatest cold I could produce to overcome this resisting power;
while  by Experiments IV. and  V. on the toad  and snail, whose
natural heat is not always the same, but is altered very materially
according to the external  heat or cold, this  power was exhausted in
a degree of cold not  exceeding 10° or 15°; and the snail being the
most  imperfect of the two, its  powers of generating heat appeared
to be much the weakest.
   That the imperfect  animals will allow of a  considerable  variation
in the temperature of heat and cold, is proved by the following ex-
periments.   The  thermometer being  at  45°, the  ball was intro-
duced by the  mouth  into the  stomach of  a frog, which  had been
exposed to the same  cold.  It rose to 49°.   I then placed the frog
in an atmosphere made warm by heated water, where I allowed  it
to  stay twenty minutes; and upon introducing the thermometer
into the stomach, it raised the quicksilver to 64°.  To what degree
 the more imperfect animals are   capable of being rendered  hotter
 and colder at one time than another, I have not yet ascertained ;*

  ' * [The snail (Cyclostomum thermale) which lives in the hot springs of Abano
 feeds, moves about with great activity, and propagates in water of the temperature
 of 100° Fahrenheit.  The Entozoa of warmblooded animals become  in a certain
 degree torpid in cold water, but revive and exhibit lively motions when placed
 in warm water of 95° Fahrenheit.] 
ON ANIMALS PRODUCING HEAT.              159
but the torpidity of these  animals in  our winter is probably owing
to the great change wrought in their temperature by the external
heat and cold.  The cold in their bodies is to such a degree  as in
a great measure to put a stop, while  it  lasts, to the vital functions;
While in warmer climates no such effect is produced.*
   This variety (in  the  power of producing  heat) not  only  takes
place in animals of different orders, but in some degree in the  same
animal at different  ages, even according to the different age of the
parts in the same animal:  a young  animal  requires more warmth
than one full-grown ; and although  an animal  is equally old in  all its
original parts, yet,  there are often new ones formed in consequence
of disease; and we find that these new  or young parts  in animals
are not so able to support life as the old, at least for some time : but
as animals  are of different ages, and the same animal  is  always
growing older, and of course more and  more perfect, they then be-
come  more  capable of  generating heat  than  when   they  were
younger.f  This, however, has its limitations,  for  after a certain
period  they again  lose  this power, and  therefore  require  a less
strongly conducting medium, or warm atmosphere.
   This power of  generating  heat seems  to be a property  in an
animal while alive.  In the more perfect animals it is to preserve a
standard heat; and as they are most commonly in an  atmosphere
colder than  themselves,  they have most commonly occasion  to
exert  it, and  it is therefore a power  only of  opposition  and resist-
ance ; for it is not  found  to exert itself spontaneously and unpro-
voked, but  must always be excited by the energy of some external
frigorific agent, or disease; yet it is natural  to such animals that
this power should  be  called forth, as  will be observed by and by.
It does not depend on the  motion  of the blood, as some have sup-
posed, because it likewise  belongs  to animals which have no circu-
lation :J and  the nose of a dog, which is always nearly of the same

  * [The Reptiles and many of the Invertebrate animals of tropical climates seek
their hiding-places and fall into a state of lethargy during the dry season, when
the heat is  most intense.  A  quadruped of Madagascar, the tenrec, which is
nearly allied  to  our hedgehog, becomes lethargic at the dry season, when  its in-
sect food is inaccessible.]
  f [Young  animals  consume, in proportion, less oxygen than adults;  conse-
quently, a less proportion of carbonic acid is formed in the change of the arterial
into the venous blood, and a less amount of heat is extricated. When exposed
to cold they become torpid, lose their heat, and also their sensibility, in which
latter circumstance, and in some other points, they differ considerably from the
hybernating animal in its state of lethargy.]
  X [An argument of this  importance  deserved to be stated with more circum-
stance.  Mr. Hunter does not say  what the  animals are which have no circu-
lation.  It is possible, however, that he was alluding to bees. But these insects
we know enjoy a circulation, governed, as his own dissections show, by a dorsal
heart.  And  insects manifest the power of generating  heat above that of other
invertebrate animals precisely in consequence of the greater activity of their loco-
motive, respiratory, and sanguiferous functions.  It is true, however, that mere
motion of the blood is not a cause of animal heat, because the circulation goes on
in the hybernating animal  when in its cold and lethargic state ; but the blood's
motion  is here inoperative as a cause of heat, because in torpidity no chemical 
160
HUNTER ON THE ANIMAL CECONOMY.
 heat in all temperatures of the air, is well supplied with blood ;* al-
 though we must allow, where this power is greatest the circulation
 is the quickest.  Neither can it be said to depend upon the nervous
 system, for it  is found in animals  that  have  no brain or nerves.
 However, it must be allowed that all that class which possess this
 power in the highest degree have  the largest  brain, although this
 power is not in the least in proportion to the quantity of brain in that
 class.f  It  is most probable  that  it arises  from some other prin-
 ciple ;  a principle so connected with life that it can, and does, act
 independently of circulation,  sensation, and volition, and  is that
 power which preserves and regulates the internal machine.  This
 power of generating  heat is  in  the highest perfection when  the
 body is in health; and in many deviations from that state we find
 that  its action is extremely uncertain  and  irregular, sometimes
 rising  higher  than the standard,, and  at other  times falling  much
 below it.  Instances of this we have in different diseases, and even
 in  the  same disease, within very short intervals of time.   A very
 remarkable one  fell under my own  observation, in a gentleman
 who was seized with an apoplectic fit; and while he lay insensible
 in bed, covered with blankets, I found  that his whole body would,
 in an instant, become  extremely cold  in  every part, continuing so
 for some  time; and, as  suddenly, would become  extremely hot.
 While  this  was going on alternately there was no sensible altera-
 tion in  his pulse for several hours. J
   Being satisfied of the foregoing fact, that  animals had a power
 of generating heat, I pursued the subject still'further;  not so much
 with a  view to account for animal heat, as to observe the different
 phenomena, with the variations or difference in the heat in different

 change takes place in the blood during its passage through the capillaries, either
 of the systemic or pulmonic systems of vessels;  it is only venous blood that is
 moving.]
  * [The temperature of the nose of a dog is lowered by the constant evaporation
 of the moisture excreted from its surface; when this secretion is checked in con-
 sequence of internal disease, then the nose soon grows hot; and the dryness and
 heat of this part, both in the dog and other animals, form a common symptom of
 loss of health, as we have frequently had occasion to observe in the animals in
 the Zoological Gardens.]
   f[Although, from the experiments on vegetables subsequently given, it appears
 that vital heat is not dependent on a nervous system ; yet it has been shown that
 the production of heat in warm-blooded animals is modified by the nervous in-
 fluence.  See the Physiological Researches, ' On the Influence of the Brain on
 the action of the Heart, and on the generation of Animal Heat,' by B. C. Brodie,
 F.R.S., Phil. Trans., vol. ci., p. 36; vol. cii., p.  380; also the experiments of
Home and Mayo, Phil. Trans.,  vol. cxv.,  p. 7; and by Legallois, Annales de
 Chimie, t. iv. 1817.]                               J   s
  X [Here ends the first paper in the 65lh vol. of the Phil. Trans.  The second
 cgmmunicauon commences as follows : " In the course of a variety of experiments
 on animals* and vegetables, I have frequently observed that the result of experi-
 ments in the one has  explained the ceconomy of the other, and pointed out some
 principle common to both; I have therefore collected some experiments which
relate to  the heat and cold  of those substances;" and then proceeds  as  in the
text.] 
ON ANIMALS PRODUCING HEAT.
161
animals.  In the course of my experiments, having  found varia-
tions in the degree of heat  and cold in the same experiment, for
which  I could not account, I suspected that this might arise from
some imperfection in the construction of the thermometer.   I .men-
tioned  to Mr. Ramsden my objections to the common construction
of that instrument, and my ideas of one more  perfect in its nature,
and better  adapted  to  the  experiments in which I was engaged.
He accordingly made me  some very small thermometers, six or
seven  inches long, not above two-twelfths of an inch thick in the
stem, having the external diameter of the ball very little larger
than that of the stem, on which was marked the freezing poTnt.
The stem was embraced by a small ivory scale, so as to slide upon
it easily, and retain any position.  Upon the hollow surface of this
scale were marked the degrees, which were seen through the stem.
By these means the size of the thermometer was very much reduced,
and it could  be  applied to soft bodies with much more ease  and
certainty, and in many cases in which the former ones could not
be conveniently  used; I therefore repeated  with  it  such of my
former experiments  as had not at first proved satisfactory,  and
found the degrees of heat very different, not only from what I  had
expected, but  also from what I had found  by  my former  experi-
ments  with thermometers of the common construction.
  I have observed above, and  find  it supported by every experi-
ment I have made on the heat and cold of animals, that the more
perfect have the greater power of retaining a certain degree of heat,
which  may be called their standard heat, and allow of much  less
variation than the more imperfect animals ;  however, it will appear
from the three experiments which I am now going to relate, that
many,  if not all of the  more perfect, are still incapable of  keeping
constantly to one degree, but may be  altered from their standard
heat either  by external applications or disease.  These variations
are much greater below  that standard than above it, the perfect
animals having a greater power of resisting heat than  cold, so that
they are commonly.near their ultimate heat.   Indeed we  do  not
want any other proof of a variation than  our own feelings, being
all sensible of heat and of cold,  which sensations could not be pro-
duced without an alteration really taking place in the parts affected;
and that  alteration could not take  place  if they  did not  become
actually warmer or colder.   I have often cooled my hands to such
a degree that I could warm them by immersing them in water  just
pumped;  therefore my hands were really colder  than the pump-
water.
  An increase of absolute heat must alter the texture or position of
the parts, so as to produce the sensation which we call heat:  and
as that heat is diminished, the  texture or position of  the  parts is
altered in a contrary way, and, when  carried to a certain degree,
becomes the cause of the sensation of cold.  Now these effects could
not take place in either case without an increase or decrease of ab-
solute  heat  in the part; heat, therefore, in some one of its different
                              15* 
162          HUNTER ON THE ANIMAL  CECONOMY.
degrees, must be present.  I shall not in this place attempt to settle
whether heat is a  body or matter, or only a property of matter,
which appears to  me to be merely a difference in terms; fora
properly must belong to something.   When heat is applied  to the
surface of the body the skin becomes in some degree heated accord-
ing to the application, which may be  carried so far as actually  to
burn  the living parts :  on the contrary, in a cold atmosphere a man s
hand  may become so cold as to lose that sensation  altogether, and
change it for pain.  Absolute heat and cold may be carried so far
as even to alter the structure of the parts  upon which the actions
of life depend.
   As animals being subject to variations in the degrees of heat and
cold from external applications are of course, in this respect, affected
in some measure like inanimate matter; and therefore, as parts are
elongated or  recede  from  the  common mass, these  effects more
readily take place ;  for instance, all projecting parts and extremities,
more  especially toes, fingers, noses, ears, combs  of fowls, particu-
larly  of the cock, are more readily cooled, and are therefore most
subject to be affected by cold.   Animals are  not only subject to  an
increase and decrease of heat, similar to inanimate  matter, but  the
transition from one to the other (as far as they admit of it) is nearly
as quick.  I shall not, however, confine  myself to  sensation alone,
as that is in some  degree regulated  by habit; for. a  habit of uni-
formity in the application of heat and cold to an animal body renders
it more  sensible of the smallest variation  in  either;  while by the
habit of variety it  will become, in  a  proportional degree, less sus-
 ceptible of  all  such sensations.  This is proved  every day, in cold
 weather, by people  who are accustomed to  clothe themselves warm.
 In them the least exposure to cold air, although the effect produced
 in  the skin  is perhaps  not the hundredth part of a degree, imme-
 diately gives the sensation of cold, even through the thickest cover-
ing ;  those, on the contrary, who have been  used  to  go  thinly
 clothed, can bear the  variation of some degrees without being sen-
 sible of it;  of this the hands and feet  afford an instance in point,  ex-
 citing the  sensation  of cold when applied to another part of  the
 body, without having  before given  to the mind an  impression of
 cold existing in these parts themselves.   The  projecting parts and
 the extremities are those which admit  of the  greatest change in
 their degrees  of heat and cold  without materially affecting  the
 animal or even its sensations.   I find that  by heat or cold externally
 applied to  such parts, the thermometer may be made to rise or fall;
 but  not in an equal proportion as when applied to inanimate matter.
 Nor are the living parts cooled or heated in the same  proportion,
  as appears from the  application of the thermometerto the skin ;  for
  the  cuticle is  to be considered as a dead covering,  capable of re-
  ceiving  greater degrees of heat and cold than the living parts un-
  derneath ;  and as it  might be suspected that the whole of the varia-
  tion was in this covering, to remove any such doubt  I made the
  following  experiments. 
ON ANIMALS PRODUCING HEAT.
163
  Experiment I.  I  placed the ball of the thermometer under my
tongue where it was perfectly covered by all the surrounding parts;
and having kept it  there for some minutes, I found  that it rose to
97° : yet it rose no higher by being continued there.  I then took
several pieces of ice, about the size of walnuts, and put them in the
same situation, allowing them only to melt in part, that the appli-
cation  of cold might be better kept up, occasionally spitting out the
water  arising  from the  solution.  Having continued this for ten
minutes, I found, on introducing my thermometer, that it fell to 77°;
so that the  mouth  at this part had  lost 20° of heat.  The ther-
mometer gradually rose to 97° again; but did not  in this experi-
ment sink so low as it would have done in the hand, if a piece of ice
had been held in it for the same length of time.   Perhaps the surface
under the tongue being surrounded with warm parts  renders it next
to an impossibility to cool it below that degree ;  but I rather sus-
pect that such parts as the hand will allow  of greater latitude in
this respect, from having  insensibly acquired the  habit of varying
the degree of cold, and becoming of course less susceptible of its im-
pressions, and therefore less .easily excited.
   As a further proof that the more perfect animals  are capable of
varying their heat in some measure according to the external heat
applied, I shall adduce the following experiments made on the human
subject.
   The mouth being a part so frequently in contact  with the external
atmosphere in the "action of breathing, whatever is put into it may
be Supposed to be influenced by that atmosphere; this will always
render an experiment made in that part, relative to  heat and cold,
somewhat uncertain.  I imagined that the urethra  would answer
better, because, being an  internal cavity, it can only be influenced
by heat  and  cold  applied to  the external  skin  of the parts.   I
imagined also  that, whatever effects the  application of heat and
cold might have, they would  sooner  take place in  the urethra,  as
being  a projecting part, than in any other part of  the body; and
therefore, if living  animal substance was  in any  degree subject to
the common laws of matter in this  respect,  the urethra would  be
readily affected.  To determine this I procured  a  person  who'
allowed me to  make such experiments as I thought necessary.
   Experiment  II.   I  introduced the  ball of my thermometer into
the urethra about an inch ; which having remained there about a
minute, the quicksilver rose to 92°; at two inches  it  rose to 93°; at
four inches to  94°; and when the ball had  got as  far as the bulb
of the urethra, where it was surrounded by warm parts, the quick-
silver  rose to 97°.
   Experiment III.  These parts being immersed for one minute in
water, heated only  to 65°. and the thermometer introduced about an
inch and a half into the urethra, the  quicksilver rose to 69°; which
was repeated several times with  the  same result.  To discover if
there  were any difference in the quickness of the  transition of heat
 and cold in living and dead parts, and to determine  if the extent to 
164
HUNTER ON THE ANIMAL CECONOMY.
which each would go  were likewise different, I procured a  dead
penis, for the purpose of making the comparative experiments that
follow;  being clearly of opinion that  all such trials should be as
similar as possible, except in  those points where  the difference (if
there is any) makes the essential part of the experiment.
   Experiment IV.  The  heat of the penis of a living person, an
inch and a half within  the  urethra, being found exactly 92°; and
the dead one being heated to the same degree, I had both immersed
in the same vessel,  with  the water at 50°,  when, by introducing
the thermometers several  different times, I was able to note the
comparative  quickness with which  they cooled from 92°, and ob-
served that the dead cooled sooner  by two or three minutes; the
living sunk the quicksilver to  58°, and the dead to 50°:  the ther-
mometer, although continued there some time longer, fell no lower.
I repeated  this experiment several  times, with the  same  result;
although at one time  there was a small difference in the degrees of
heat of  the penis  and also of the water; but the difference in the
result was nearly  proportional in  all the three different trials, there-
fore the same conclusions may be drawn from them.   In  these last
experiments very  little difference  was observed between  the cool-
ing of a dead  and of  a living  part; a circumstance  which we
cannot suppose to take place uniformly through the whole body,
as in that case living animals would always be of the same degree
of heat  with the atmosphere  in which  they live.   The  subject of
these experiments not choosing to have the part cooled lower than
53° or 54°,  prevented my  observing if the  powers of generating
heat were exerted to  a greater degree when  the heat was brought
so low as to  threaten destruction; but  by some experiments  on
mice, which will  be  related hereafter, it will appear that the ani-
mal powers are roused  to exert  themselves  in this  respect when
necessary.
  Having found,  from the above experiments, that parts of  an
animal were capable  of being cooled below the common or natural
heat, I proceeded  to make others, with  a view to ascertain if the
same parts were  capable of being  made much hotter  than the
standard heat of  animals.  The experiments were  made  in the
same manner a3 the  former, only the water was now hotter than
the natural  heat of the animal.
  Experiment V.   The natural  heat of  the parts  being  92°, they
were immersed for two  minutes in  >vater heated to 113°, and, the
thermometer  being  introduced as before, the quicksilver rose to
100° and a half.  This experiment I also repeated several  times,
but could not raise the heat of  the penis beyond  100£°.  this was
probably owing to the person not being able at  the time to bear
the application of  water warmer  than 113°.  By was of  compari-
son, I made
  Experiment VI. The living and dead  parts being both immersed
in water, gradually made warmer and warmer from 100° to 118°,
and continued in that heat for some minutes, the dead part raised' 
ON ANIMALS PRODUCING HEAT.
165
 the thermometer to 114°, while the living raised it no higher than
 102i°.   It was observed, by the person on whom the experiment
 was made, that after  the parts  had been  in  the water about  a
 minute, the water did not feel hot, but on its being agitated it felt
 so hot that he could hardly bear it.  Upon applying the thermometer
 to  the sides of the living glans, the quicksilver immediately fell
 from 118° to about 104°, while it did not fall more than a degree
 when put close to the dead;  so that the living glans cooled the sur-
 rounding water to a certain distance.*
   Experiment VII.  The heat of the rectum in the same man was
 98° and a half exactly.
   In the second, third, fourth, fifth, and  sixth experiments, an  in-
 ternal cavity,  which  is  both very vascular and sensible, was
 evidently influenced by external heat and cold, though only applied
 to the skin of the  part; while in the seventh experiment another
 part of the same body, where external heat  and cold could make
 little or no impression, was of the standard heat.   Although it will
 appear, from experiment, that the rectum is not the warmest part
 of an animal, yet, in order to  determine how far the heat could  be
 increased by stimulating the  constitution to  a degree sufficient to
 quicken the pulse, I repeated the seventh experiment after the man
 had eaten a hearty supper and drank a bottle of wine, which  in-
 creased the pulse from 73°  to 87°, and yet  the  thermometer only
 rose to 98° and a  half.
   Having formerly made experiments upon dormice during ihs
 sleeping season, with a view to see if there were any  alteration in
 the animal ceconomy at that time, I found among my  notes an ac-
 count of some which appear to our present purpose; but to be more
 certain of the accuracy of the former experiments, I repeated them
 with my new thermometer.
   Experiment VIII. In a room, in which the temperature of the air
 was between 50° and 60°, a small opening was made in the belly of
 a dormouse, of a sufficient size to admit the ball of my thermometer,
 which, being introduced into the belly at about the middle of that
 cavity, rose to 80°, and no higher.
   Experiment IX. The mouse was put into  a cold atmosphere of
 15° above 0, and  left  there  for fifteen minutes; after which, the
 thermometer being introduced a second time, it rose to 85°.
   Experiment X.  The mouse was again put into a cold atmosphere
 for fifteen minutes; and the thermometer -being introduced, the
 quicksilver at first rose to 72° only, but gradually came up to 83°,
 84°, and 85°.
  Experiment XI. It was put a third time into the cold atmosphere,
 and allowed to stay there for thirty minutes: the lower part of the

  * This might furnish an useful hint respecting bathing in water, whether colder
 or warmer than the heat of the body : for if intended to be either colder or hotter,
it will soon be of the same temperature with  that of the body; therefore in a large
bath the patient should move from place to place, and in a small one there should
 be a constant succession of water of the intended heat. 
166          HUNTER ON THE ANIMAL CECONOMY.
mouse, at the bottom of the dish, was almost frozen; the whole of
the animal was  numbed, and a  good deal weakened.   The  ther-
mometer being introduced, the heat was found to vary  in different
parts of the  belly: in the pelvis, near the parts  most  exposed to
the cold, it was as low as 62°; in the middle, among the intestines,
about 70°; but near the diaphragm  it  rose to 80°, 82°, 84°, and
85°; so that in the middle of the body the  heat had decreased 10°.
Finding a variation in  different  parts of the same cavity in the
same  animal,  I  repeated the   same experiments  upon  another
dormouse.
  Experiment XII. Having  brought a healthy dormouse, which had
been asleep from the coldness of the atmosphere, into a room in
which there  was a fire (the  atmosphere at 64°), I introduced the
thermometer into its belly, nearly at the middle, between the thorax
and pubis, and the  quicksilver rose to 74° or 75°;  turning  the ball
towards the  diaphragm, it rose to 80°;  and when I applied it to the
liver, it rose to 814°.
  Experiment XIII. The mouse being placed in an atmosphere at
20°, and left there  half an hour, when  taken  out was  very lively,
even much more so than when put in.  Introducing the thermometer
into the lower part of  the belly,  the quicksilver rose to  91°; and
upon turning it up to the liver to 93°.
  Experiment XIV. The animal being replaced  in the cold atmo-
sphere at 30° for an hour, the thermometer was  again introduced
into  the belly; at the  liver it rose  to 93°;  in the pelvis to 92°; the
mouse continuing very lively.
   Experiment XV. It was again put  back into an  atmosphere,
cooled  to 19°,  and left there  an hour;  the  thermometer at the
diaphragm was 87°; in the  pelvis  83°; but the animal was now less
lively.
 •  Experiment XVI. Having been put  into its cage,  the thermo-
meter being placed at  the diaphragm, in two hours afterwards was
at 93°.
   As I  was  unable to procure  hedgehogs in  the torpid state, to
ascertain their heat during that period, I got my friend Mr. Jenner,*
surgeon, at Berkeley, to make the same experiments on that animal,
that I might compare  them with those  in  the dormouse;  and his
account is as follows :
   " Experiment I.  In the winter, the atmosphere at 44°, the heat
of a torpid hedgehog,in the pelvis, was 45°, and  at the diaphragm
48i°.
   "Experiment  II.  The atmosphere  26°, the  heat of a  torpid
hedgehog, in the cavity of the abdomen, was reduced so low as 30°.
   " Experiment III.   The same hedgehog was exposed to the cold
atmosphere  of 26° for two days, and the  heat of the  rectum was
found to be  93°; the wound in the abdomen being now  so small
that it would not admit  the thermometer.
• [Afterwards Dr. Jenner, the discoverer of Vaccination.] 
ON ANIMALS PRODUCING HEAT.
167
  " A comparative experiment was  made  with a puppy, the  at-
mosphere at 50°; the heat in the pelvis, as also at the diaphragm,
was 102°.                      f    »                 r   o
  " In summer, the atmosphere at 78°, the heat of the hedgehog,
in an active state, in the cavity of the abdomen, towards the pelvis,
was 95°; at the diaphragm 97°."
  We  find from these experiments, that the heat of the animal is
increased under  the circumstances  of  cold, whenever  there  are
actions to be carried on for which heat is necessary.
  In the  experiments on the first dormouse  the  heat of. the animal
was 80°, which is below the standard heat of  the actions of that
animal;  and  after being put  into the cold mixture its  heat  was
raised to 85°.  In the second  dormouse the heat was  raised, by
repeated experiments, from  75° to 93°.  This  question naturally
occurs here: Was the increase of heat in the animals generated to
resist the artificial cold produced by  placing them in a cold atmo-
sphere?  or was it owing to  a wound having  been  made into, the
cavity  of the abdomen, and an exertion of the animal powers being
required  to repair the injury, which  exertion  could not take place
without the increased degree of heat  1   That it was in consequence
of the wound, appears evident from the experiment made  upon the
second hedgehog; for in an atmosphere of* 26° of heat it was in a
very torpid state, and did  not raise the  thermometer higher than
30°; but after being wounded and put back into the cold, and kept
there for two days, its heat in the rectum was 93°, and so far from
being torpid,  it was lively, and the  bed in which it lay felt warm.*
  Why the heat of the dormouse should be so  low  as  80°, in an
atmosphere of between 50° and  60°, is not easily accodnled  for,
except as the effect of sleep.   But I should very much suspect that
sleep, simply  considered, is out of the question, it being an effect
that takes place in all degrees of heat and cold.  In animals whose
voluntary actions are  suspended by cold, that appears to  produce
its effect  by acting in a certain degree as a sedative, in consequence
of which the  animal faculties are proportionably weakened, though
they still retain,  even under  such circumstances, the  power of
carrying on all the functions of life.  Beyond this point cold seems
to act as a stimulant, and rouses the  animal powers to action  for
self-preservation.   It is more than probable that most  animals  are
in this  predicament, and that there is a degree of cold corresponding
with every particular order of animals,  by which, when  applied,
the voluntary actions must be suspended.
  When a man is asleep he is colder than when awake;  and I find
in general that the difference is about  one degree and a half; some-
times less.   But this difference in the degree of cold between sleep-
ing and  waking is not a cause of sleep, but an effect; for many
diseases  produce  a much greater  degree of cold in the animal

  * It is found, from experiments, that the heat of an inflamed part is nearly the
greatest or standard heat of the animal, it appearing to be a part of the process
of inflammation to raise the heat up to the standard. 
168           HUNTER  ON THE ANIMAL CECONOMY.
 without giving the least tendency to sleep ; therefore the inactivity
 of animals from cold must be different from sleep.   Besides all the
 operations of perfect life, as digestion, sensation, &c,  are going on
 in the time of  natural  sleep, at least in  the  perfect animals ; but
 none of these  operations  are  performed in the  torpid state of
 animals.*
   To see if the result of these experiments  upon dormice was pe-
 culiar to that species, I wished to repeat the same experiments upon
 common mice, for which purpose, in
   Experiment XVII. I made use of one strong and vigorous ;  and
 the atmosphere being at 60°, I introduced the thermometer into the
 abdomen ; the  ball  being at  the diaphragm  the  quicksilver was
 raised to 90°, but  at the pelvis only to 96|°.
   Here  there was a real difference of  about 9° between the dor-
 mouse and the common, the. dormouse only raising it to 80°, in two
 animals  of the same size, in some degree of the same genus, and at
 the same season of the year, and the atmosphere of nearly the same
 temperature.
   Experiment XVIII. The same mouse  was put into a cold  atmo-
 sphere of 13° for an  hour, and then the thermometer was introduced
 as before; Jbut  the animal had lost heat, for the quicksilver at the
 diaphragm was raised only to 83°, in the pelvis to  78°.
   Here  the real heat of the animal was diminished 16° at the dia-
 phragm,  and  18° in  the pelvis, while in  the dormouse  it gained 5°,
 but lost upon a repetition.
   Experiment XIX. In order to determine whether an animal that
 is weakened has the same powers, with  respect  to  preserving heat
 and cold, as one that is vigorous and strong, I weakened a mouse


  * [Some recent experiments of Dr. Marshall Hall confirm the accuracy of the
 distinction here drawn  between sleep and  torpidity, and also  show that the
 ordinary sleep of hybernating warm-blooded animals differs from that  of non-
 hybernating species, by  inducing a more impaired state of the respiration, and a
 diminution of the power  of evolving of heat.  Although a consciousness or sen-
 sibility be  lost, automatic susceptibility of impressions is  remarkably perfect
 during torpidity.  Dr. Hall  states that the slightest touch applied to one of the
 spines of  the torpid hedgehog immediately rouses it to draw a deep sonorous
 inspiration, which is its  characteristic response to such disturbance while in that
 state.  The merest shake induces few respirations in the hybernating bat.  (Phil.
 Trans., 1832, p. 15.)  So also with respect  to  circulation,  this  vital operation
 appears to be performed uninterruptedly, though slowly, during hybernation.
 M. Prunelle (Annates du  Museum, torn, xviii., p. 28), found  that  the pulsations
 of the heart of  a bat, which, while  it is awake and active amount to 200 in a
 minute, are reduced to 50 or 55 when it is torpid.  Dr. M. Hall, who succeeded,
by an ingenious contrivance, in subjecting the wing of a torpid bat to microscopi-
 cal examination, found the circulation to be slow in the minute arteries and veins;
 but the beat of the heart was regular, and generally about twenty-eight times in
 a minute. (Ibid.  p. 17.)  The blood which is  thus circulated is venous, the respi-
 ration being nearly, if not totally, suspended ; and its propulsion  in this state is
 explained on the augmented irritability of the muscular system, which is mani-
 fested by the double heart of the torpid mammal being stimulated to  contract by
 carbonized blood, like  the heart of the cold-blooded and slow-breathing batrachian
 reptile.] 
ON ANIMALS PRODUCING HEAT.
169
by fasting, and then introduced the ball of the thermometer into its
belly ;  the ball being at the diaphragm, the quicksilver rose to 97°;
in the pelvis to 95°, being two degrees colder than the strong mouse.
The mouse being put into an atmosphere as cold as the other, and
the  thermometer again  introduced, the quicksilver stood at 79° at
the  diaphragm, and 74° in the pelvis.
  In this experiment the  heat at the diaphragm  was" diminished
18°, in the pelvis 21°.
  This greater diminution of heat in the second than in the first we
may suppose  proportional to  the decreased power of the animal,
arising from want of food.
  To determine how far different parts of other animals than those
already mentioned were of different degrees  of heat, I made the
following experiments upon a healthy dog.
  Experiment XX. The ball of the  thermometer being introduced
two inches  within the rectum, the quicksilver rose  to  1004°.  The
chest of the dog was then opened, and a wound made into the  right
ventricle of the heart; and immediately on the ball being introduced,
the  quicksilver  rose to 101° exactly.   A  wound  was next made
some way into the substance of the  liver, [and  the  ball being intro-
duced, the quicksilver rose to 1003°.  It was next introduced into
the  cavity of the stomach, where it stood exactly at- 101°.   All
these experiments were made within a few minutes.
  Experiment XXI. The  thermometer was introduced  into the
rectum of an ox, and the quicksilver rose exactly to 99£°.
  Experiment XXII. This was also repeated upon  a rabbit, and
the  quicksilver rose to 99i°.
  From experiments on mice and upon the dog, it plainly appears
that every part of an animal  is  not of the same degree of heat;
and hence  we  may reasonably infer, that the heat of  the  vital
parts of man  is  greater than either  the  mouth,  rectum, or the
urethra.
  To determine how far my idea was just, that the heat of animals
varied in proportion to their degree of perfection, I  made the fol-
lowing experiments upon fowls, which I considered as one remove
below what are commonly called quadrupeds.
  Experiment XXIII.  I  introduced  the ball of the thermometer
successively into the intestinum rectum of several  hens, and found
that the quicksilver rose as high as 103°, 1031°, and in one of them
to 104°.
  Experiment XXIV.  I  made the  same experiments on several
cocks, and  the result was the same.
  Experiment XXV. To determine  if the heat of  the hen was in-
creased when she  was prepared for incubation,  I  repeated the
twenty-third experiment upon several sitting or clucking  hens;  in
one the quicksilver rose to 104°, in another to 103^°, in a third  to
103°, as in  the twenty-third experiment.
  Experiment XXVI. I placed the ball of the thermometer under
                               16 
170
HUNTER ON THE ANIMAL CECONOMY.
the same hen, in whose rectum the quicksilver was raised to 104 ,
and found the heat as great as in the rectum.
  Experiment XXVII.  Having taken some of the eggs from under
the same  hen, where the chick was about three parts formed, I
broke  a hole  in the shell, and, introducing  the ball  of the ther-
mometer, found  that the quicksilver rose  to (J9i°.  In some  that
were addled I found the heat not so high by two degrees;  so  that
the life in the  living egg assisted in some degree to support its own
heat.
  Is the increase of three or four degrees of heat, which is the dif-
ference found  between the fowl and the quadruped, for the purpose
of incubation ?  The heat in the eggs, which was caused and  sup-
ported   by that of the fowls, was not  above the standard of the
quadrupeds ; and it would probably have been less if the heat of the
hen had not been so  great.
  Finding,  from  the above  experiments,  that  fowls  were some
degrees warmer  than  that class  commonly  called  quadrupeds
(although  certainly less perfect animals), I chose to  continue the
experiments upon  the same principle, and made the following upon
those of a  still inferior .order.  The next remove from  the fowl
being what is  commonly called the Amphibia.
  Experiment XXVIII. I  introduced  the thermometer  into  the
stomach, and  afterwards into the anus of a  healthy viper, and the
quicksilver rose from 58° (the heat  of the atmosphere in which  it
was)io 68°; so  that it was  ten degrees warmer than the  common
atmosphere.*
  Experiment XXIX.  Having ascertained the heat of the water in
a pond, in which there were  carp, to  be 65^°, I  took a carp out of
this water, and having introduced the thermometer into its stomach,
the quicksilver rose to 69°; so that the difference between the water
and the fish  was only 3|°.f
  Experiment XXX. The heat of the atmosphere at 56; some
earthworms were  put into a glass vessel, and a  thermometer being
immersed among them, the quicksilver stood at  58i°.
  This experiment was repeated ;  the atmosphere at 55° : and the
worms were found to be 57°.
  Experiment XXXI.  The  atmosphere at  54°; four  black slugs

  ' [The observations of Czermack correspond with the above experiment.  He
found that the difference  between the temperature of the  animal and  that of the
surrounding medium was greater  in serpents and lizards than in other reptiles.
The temperature of a turtle (Chelonia Mydas)  was 82° when the surrounding
atmosphere was  84°.  That of a frog was 48° when the surrounding water was
44°.  That of a Proteus was 64°, the surrounding water being 56°.]
  f [Certain saltwater fishes, as the bonito and thunny, which  have the  gills
supplied with  nerves of unusual magnitude, and therefore probably enjoy a  more
energetic respiration, which have also a very powerful heart, and the  quantity of
red blood such as to give the muscles a dark red colour, manifest a higher degree
of temperature than the white fishes of fresh water, on which Mr.  Hunter experi-
mented. Dr. John Davy found that the bonito had a temperature of 99° Fahren-
heit when the surrounding medium was 80°.5.  See Philos. Trans., 1835.] 
ON ANIMALS PRODUCING HEAT.
171
were put into a small vessel, and a thermometer immersed among
them stood at 55^°.
  Experiment XXXII.  The atmosphere at 56°; three leeches were
put into a small glass vessel, and a thermometer immersed among
them stood at 57°.
  This experiment was repeated ; the atmosphere at 54°;  when the
thermometer stood at 55ic.
  To see  how far the colder animals had a power of preserving
their standard heat when exposed  to severe  cold, I made the fol-
lowing experiments.
  Experiment XXXIII. A viper, whose heat was 68°, was put into
a pan, and the pan into a cold mixture of about 10°;  after remain-
ing there about ten minutes had its  heat reduced  to  37°.  Being
allowed to stay ten minutes  longer, the mixture at 13°, its  heat
was reduced to 35.°   It was  continued ten minutes more  in the
mixture at 20, and its  heat was reduced to 31°;  nor  did it sink
lower, its  tail  beginning to freeze, and the animal now becoming
very  weak.  It may  be remarked, that  it cooled  much slower
than many of the animals mentioned in the following experiments.
  The frog being in its structure more  similar to the viper  than
to either the fowl or fish, I made the following experiments on that
animal.
  Experiment XXXIV. I introduced the ball of the thermometer
into its stomach, and the quicksilver stood at 44°.  I then put the
frog into  a cold  mixture,  and the  quicksilver sunk to 31<*  the
animal appeared almost dead, but recovered very soon: beyond
this point  it was not possible to lessen the heat without destroying
the animal.  But its decrease of heat was quicker than in the viper,
although the mixture was nearly the same.
  The next experiments were made  on fishes.
  Experiment  XXXV. In an eel, the heat in the stomach, which at
first was at 37°, sunk, after it  had  been some time in  the cold
mixture, to 31°.  The  animal at that time appeared dead, but was
found to be alive the next day.
  Experiment  XXXVI. In  a snail, whose heat was at 44°, it sunk,
after it had been put into the cold mixture, to 31°, and  then the
animal froze.
  Experiment  XXXVII. Several  leeches having been put  into a
bottle, and the bottle immersed in  the cold mixture,/the ball  of the
thermometer being placed  in  the  middle of them, the quicksilver
sunk to 31°; and by continuing the immersion for a sufficient time
to destroy life, the  quicksilver rose  to  32°, and then the leeches
froze.  In all  these experiments  the animals when thawed were
found dead.
  Finding that animals of the imperfect classes will, without life
being totally extinguished,  admit of their heat being reduced to that
point  at which the dead solids  and fluids freeze, but if sunk much
below that, death must be  the consequence, I wished  therefore to
be able to determine to what degree the heat of the  animal could
be raised. 
172
HUNTER ON THE ANIMAL CECONOMY.
  Experiment XXXVIII. A healthy viper was placed in an atmo-
sphere heated to 108°, and allowed to  stay seven minutes; when
the heat of the animal in the  stomach and anus was found to be
92^°; beyond which it could not be raised in the above state of the
atmosphere.  The same experiment was made upon frogs, with
nearly the same result.
  Experiment XXXIX. An eel, very weak, its heat at 44°, which
was nearly that of the atmosphere, was put into water  heated to
65°, for fifteen minutes;  and, upon examination, it was found of the
same  degree of heat with the water.
  Experiment XL. A tench, whose heat was 41°,  was  put  into
water at 65°, and left there ten minutes; the ball of the thermome-
ter being introduced both into the stomach and rectum, the quick-
silver rose to 55°.   These  experiments were repeated with nearly
the same result.
  To determine whether life had any power of resisting heat and
cold  in  inferior  classes of animals,  I made comparative trials
between living and dead ones.
  Experiment XL1.  1 took a living and a dead tench, and a living
and a dead eel, and  put  them into warm water; they all received
heat equally fast:  and when they were  exposed to cold, both the
living and the dead admitted the cold likewise with equal quickness.
  I-had long suspected  that  the  principle of life was not wholly
confined  to animals, or animal  substance  endowed with visible
organization and spontaneous  motion;  but supposed that the same
principle might exist in animal substances, devoid of  apparent
organization  and  motion, when  the  power of  preservation  was
simply required.
  I was led to this opinion about twenty years ago, when busied in
making drawings  of the  growth of the chick in the process of incu-
bation.  I then observed, that  whenever  an egg was hatched, the
yolk  (which is not  diminished  in the time  of incubation)  was
always  perfectly sweet to the very last; and  that the  part of the
albumen,  which  has not  been expended on  the  growth of  the
animal,  some days  before hatching,  was  also perfectly sweet,
although both were  kept in a heat of 103° in the hen's egg for
three  weeks, and in  the  duck's for four; but I observed that if an
egg was not hatched, that egg became putrid in nearly the same
time with  any other dead animal matter.
   To determine from other tests how far eggs possessed a living
principle, I made the following experiments.
   Experiment XLII. After having placed an egg in a cold about 0,
till it  froze, I allowed  it to thaw;  by which process it  was to be
supposed the preserving powers of the egg must be destroyed.  I
then  put  this egg into  the  cold mixture, and  with it one newly
laid, and found  the difference in freezing was seven minutes and a
half, the fresh one  so much-longer time  resisting the powers of
cold.
   Experiment XLIII. A new laid egg being put into a cold atmo- 
ON ANIMALS PRODUCING HEAT.
173
sphere, fluctuating between 17° and 15°, took-above half an hour
to freeze;  but when thawed and put into an  atmosphere at 25°, it
froze in half  the time.  This experiment was repeated frequently
with nearly the same result.
   To ascertain the  comparative degree of heat  between a living
and a dead egg, and also  to  determine whether a living  egg be
subject to the same laws with the more imperfect animals,  I made
the following experiments.
   Experiment XLIV. A fresh egg, and one which had been frozen
and thawed, were  put into the cold  mixture at 15°: the  thawed
one soon came to 32°, and began to swell and congeal; the fresh
ono sunk to 29^°, and in twenty-five minutes later than the dead
one it rose to 32°, and began to swell and freeze.
   In this experiment the effect on the fresh egg was similar to that
produced on the frog, eel, snail, &c, where life  allowing the heat
to be diminished two or three degrees below the  freezing point,
afterwards  resisted  all  further decrease;  but the  powers of life
being expended by this exertion, the parts froze like any other dead
animal  matter.
   From these  experiments it  appears that  a fresh  egg has the
power of resisting heat, cold, and putrefaction in a degree equal to
many of the more imperfect animals; and it is more than probable
this power arises from the same principle in both.
   From the circumstance of those  imperfect  animals  (upon which
I made  my experiments) varying  their heat  so  readily, we may
conclude that  heat is not so very essential to life in  them as in the
more perfect;  although it be essential to many of the operations, or
what may be called the secondary actions of life, such as digesting
food* and propagating the  species, both which, especially the last,
requiring the greatest powers an animal can  exert.  The animals
which we  call imperfect  being  chiefly employed  in the  act of
digestion, we may  suppose  their degree of heat to be only what that
action requires ; it  not being essentially necessary for the life of the
animal  that  heat should ever rise  so high in  them as to call forth
the powers necessary for the propagation of the species.f   When-

  * How far this idea holds good with fishes,  I am not certain.
  f The  hedgehog may be called a truly torpid animal; and we find that its
actual heat is diminished when  the actions are not vigorous.*  From a general
  a [The experiments by which this important fact was established  are those
numbered I. and II., page  166.  They were made after the publication of the
original memoir in the Philosophical Transactions, in which the note consequently
commences  thus:  " How far the  animal  heat is  lowered in the more perfect
animals, when these secondary actions are not necessary, as in the bat, hedgehog,
bear, &c, I have not been able to determine, not having the opportunities of ex-
amining these animals.  Dormice are  in  a mixed  state, between the voluntary,
and involuntary, and we find the heatdiminished when the actions are not vigor-
ous ; and, from a general review of this whole subject, it would  appear that a
certain degree of heat in the animal is necessary for  digestion, and that necessary
heat will be according to the nature of the animal."—Phil. Trans. 1778, p. 91.
                               16* 
174           HUNTER ON THE ANIMAL  CECONOMY.
ever  therefore these imperfect  animals are  exposed to a cold so
great as to weaken their powers, and disable them from performing
the first of these secondary actions, they in some measure cease to
be  voluntary  agents,  and  remain in a  torpid state during that
extreme degree of cold which always occurs  during some part of
the winter in  the  countries  they  inhabit;  and the food of such
animals not being in general produced in the cold season is a reason
why this torpidity  becomes in some measure necessary.*
   From the heat of such animals sinking to  the freezing point, or
even  lower, and then becoming stationary,  and the  animal not
being able to support life in a much greater degree of cold for any
length of time, we see a reason why they should always endeavour
to procure places  of abode  in the winter where the cold seldom
sinks to that point.   We find toads burrowing, frogs living under
large stones, snails  seeking shelter under  stones and in holes, and
fishes having recourse to deep water;  the heat of  all those  places
being generally above the freezing point even in our hardest frosts ;
which  are however sometimes  so severe  as  to kill many whose
habitations are not well  chosen.
   When the  frost  is  more  intense  and of longer standing than
common,  or  in countries where  the winters  are  always  severe,
there is generally snow on the ground, and the water freezes: the
advantage arising from these two circumstances is great; the snow
serving as a blanket to the earth, and the ice to the water.f

review of this whole subject it would appear that a certain degree of heat in  the
animal is necessary for its various ceconomical operations, among which is di-
gestion ;  and that necessary heat will be according to the nature of the animal,
and, probably, the nature of the operations to be performed.   A frog will digest
food when its heat is at 60°, but not when at 35° or 40° ; and it is very probable
that, when the heat of the bear, hedgehog, dormouse, bat, &c, is reduced to 70°,
75°, or 80°, they lose their power of digestion ; or rather that the body, in such
a degree of cold, has no call upon the stomach.  That animals in a certain degree
of heat must always have food is further illustrated by the instance of bees.  The
construction of a bee is very similar to that of a fly, a wasp, &c.   A fly and a
wasp can allow their heat to  diminish, as in the fish, snake, &c, without losing
life, but a bee cannot;  therefore a bee  is obliged to keep up its heat as high as
what we call its digestive heat, but not its propagating; for which purpose they
provide against such cold as would deprive them even  of their digestive heat, if
they had not food to preserve it.
   * The torpidity induced by cold in hybernating animals is unlike that which is
similarly induced in non-hybernating animals ; in the former it is an action of
preservation, in the latter one of destruction.  See the  paper before quoted, by
Dr. Marshall Hall.]
   f Snow and ice are perhaps the worst conductors of heat of any substance yet
known.   In the first  place, they never allow their own heat to rise above the
freezing point, so that no heat can pass through ice or snow when at  32°, by
which means they become an absolute barrier to all heat that is at or above that
 degree; hence the heat of the earth, or whatever substance they cover, is retained ;
 but they are conductors of heat below 32°.  Perhaps that power decreases in pro-
 portion as the heat decreases under that point.
   In the winter 1776, a frost coming on, the surface of the ground was frozen ;
 but a considerable fall cf snow fell, and continued several weeks : the heat of the
 atmosphere during the time was often at 15° ; but so little did the frost affect the 
ON ANIMALS PRODUCING HEAT.
175
  As all the experiments I ever made upon the freezing of animals
(with a view to see if it were possible to restore the actions of life
when thawed) were tried upon whole ones; as I never saw life return
by thawing,* and wished  to  see  how far parts were similar to the
whole in  this respect, it being asserted, and  with some authority,
that parts of a man  may be  frozen, and  afterwards recover,—I
made, for this  purpose the following experiments upon an animal
of the same  class as ourselves.
  In January 1777, I mixed  salt  and ice  till the cold was about 0;
in the side of the vessel was  a hole, through which I  introduced
the ear of a  rabbit; and, to carry off the heat as fast as possible, it
was held  between two flat  pieces  of iron that went further into
the mixture.  That part of the ear projecting into the vessel became
stiff, and  when cut did not bleed ; the part divided by the scissors
flying from between the blades like  a hard chip.
  The ear having remained  in the mixture  nearly an hour, soon
thawed when taken out, began to bleed, and became so very flaccid,
as to double upon itself, from  losing its natural  elasticity.  When
out of the  mixture nearly an hour, it  became  warm:  and this
warmth  increasing to  a considerable degree,  it  also  began  to
thicken, in consequence of inflammation, while the other ear con-
tinued in its usual degree of cold.  The  day following the frozen
ear was still warm; and even  two days after retained its heat and
thickness, which continued for many days after.
  About a week after this, the mixture being the  same  as  in the
former experiment, I introduced the ears of the same rabbit through
the hole, and froze them  both: the  sound one however froze first
probably from its being considerably colder at the beginning.  When
withdrawn  they  soon thawed, both soon became warm, and the
fresh ear  thickened as the other had done before.
   Such a change in the  parts  does not always take place so quickly;

ground underneath that the surface of the ground thawed, and the earth retained
the heat of 34°, in which beans and peas will grow.
  The same thing took place in a pond  where the water was frozen  on the sur-
face to a considerable thickness: a large quantity of snow having fallen, and  co-
vered the ice, the heat of the  water  was preserved ; the ice thawed, and the snow,
at its under surface, was found mixed with  the water.
  The heat of the water under the snow was at 35°, in which fishes lived very
well.
  It would be an attempt worthy the attention of the public philosopher to
investigate the cause of the heat  of the earth, upon what principle it  is pre-
served, &c.
  * Vide Phil. Trans, for the year  1775, vol. lxv. part ii. p. 446.a
  a That animals, lower in in the scale than any which Hunter experimented
 on  with this view, may, after having been frozen, recover  life by thawing, is
 rendered at least highly probable from the following statement by Rudolphi.
 In his description of the Filaria capsularia, he observes, " Vermis vitse satis tenax
 est, ut per octiduum in frigida conservaverim, et Filarias in Harengis congelatis
rigidas  et  giacie tectas frigida affusa reviviscere viderim."  (Hist. Entoz.,
vol. ii., p. 62. 
176          HUNTER ON THE ANIMAL CECONOMY.

for on repeating the experiment on the ear of another rabbit till it
became as hard as a board, it was found to  be longer in thawing
than in the former  experiment, and much longer before it became
warm ; in two  hours, however, it 'had  acquired some degree of
warmth, and on the day following was hot and thickened.
  In the spring, 1776, I perceived that my cocks in the country
had their combs smooth, with an even edge, and not so  broad as
formerly, appearing as if near one half of them  had  been cut off.
Having inquired into the cause of this, my servant told me that it
had happened in that winter during the hard frost, he having then
observed that the combs had in part dropped off, also that the comb
of one  cock  had entirely'separated: but this I did  not see  as by ac-
cident  he was burnt to death.  I naturally imputed this effect to the
combs  having been frozen to so great  a  degree during the severe
weather as to have the  life  of the part destroyed.  To determine,
therefore,  by experiment, the solidity of this reasoning, I  made the
following experiment.
  I selected  for the purpose a very large young cock, having a comb
of considerable breadth,  with deep serrated edges, the processes of
which  were  full half an inch long.  My attempts  to freeze the sub-
stance  of the comb did not succeed ; for that, being thick and warm,
resisted the effects of the cold, and only the serrated edges were
frozen.  The frozen parts became white and hard, and when I cut off
a little  bit did not bleed, nor did the animal show any signs of pain.
I next  immersed in the cold mixture  one of his  wattles, which was
very broad and thin ; it froze very readily ;  and upon thawing both
the comb and wattle they  became warm,  but  of a  purple colov/r,
having lost that transparency which  remained in the other  parts
of the comb  and in the other wattle.   The wound in the comb now
bled freely.
  Both comb and  wattle recovered  perfectly  in about a month.
The natural colour  returned first nearest to the sound parts,  in-
creasing gradually till the whole had acquired a healthy appearance.
  There was a  very  material difference in the effect between those
fowls, the  serrated edges of whose combs I suspected to have been
frozen  in the winter of 1775-6, for  they must have dropped off.
The only way in which I can account for this difference is, that in
those fowls the parts were  kept so long frozen that the unfrozen or
active  parts  had time to  inflame,  and had brought about a separa-
tion of the frozen parts, treating them  exactly as  dead, similar to a
mortified part: and that  before they thawed, the separation was so
far completed as to deprive  them of further support.
  As it is confidently asserted that fishes are often frozen, and again
return  to motion, and as I had never succeeded in any of my trials
of the kind upon whole  fishes, I made some experiments upon par-
ticular parts, to which I was led by  having  found a material dif-
ference in the result of experiments made upon the whole, and on
parts of the  more perfect animals.
  I froze the tail of a tench, as high as the anus,  which became as 
ON THE HEAT OF VEGETABLES.
177
hard as a board : when thawed, that part was whiter than common ;
and when it moved, the whole tail moved as one piece, and the ter-'
mination of the frozen part appeared like the joint on which it moved.
  On the same day I froze the tails of two gold fishes till they be-
came as solid as a piece of wood.   They were put into cold water
to thaw, and appeared for some days to be very well; but that part
of the tails which had been frozen  had not the natural colour, and
the  fins of the tails became ragged.  About three weeks after, a fur
came all over the frozen parts ;  their  tails  became lighter, so that
the  fishes were suspended in the water perpendicularly; they had
almost lost the power of motion ; and at last died.   The water in
which they were kept was New River water, shifted every  day,
and in quantity about ten gallons.
  I made  similar experiments upon an order of animals still inferior,
viz. common earth-worms.
  I first froze the whole of an  earth-worm as a standard;  when
thawed it was perfectly  dead.
  I then froze the anterior half of another  earth-worm; but the
whole died.
  I next froze the posterior half of an earth-worm; the anterior
half continued alive, and separated itself from the dead part.
  From some of these experiments  it appears that the more imper-
fect animals are capable of having their heat and cold varied very
considerably, but not according to the degree of heat or cold of the
surrounding medium in which they can support life; for they can
live in a cold considerably below the freezing point, and yet the
living powers of the animal will not allow their heat to be diminished
much beyond 32°.  Whenever the surrounding cold  brings them so
low, the power of generating  heat takes place;  and if the cold is
continued, the animals exert  this power till life is destroyed ; after
which they freeze, and are immediately capable of admitting any
degree of cold.
15. EXPERIMENTS  AND OBSERVATIONS  ON VEGE-
       TABLES,  WITH  RESPECT TO THE POWER OF
       PRODUCING HEAT.*

  To ascertain whether vegetables could be frozen, and afterwards
retain all their properties when thawed, or had the same power of
generating heat with animals, I made several experiments.   Vege-
table juices when squeezed out of a  green plant, such  as cabbage
and  spinage, froze in a cold of about 29°; and between 29° and 30°

  * [This paper includes those portions of the two communications to the Royal
Society, On the Heat of Animals and Vegetables, which were omitted by Hunter
in the ' Animal CEconomy.'  See Phil. Trans., lxv., 1785, p. 450.] 
173          HUNTER ON THE ANIMAL CECONOMY.
thawed again, which is about 4° above the point at which the animal
juices freeze and thaw.
  Experiment I. I took a young growing bean, about three inches
long in the stalk, and put it into the leaden vessel with common
water, and then immersed  the whole  into the cold mixture,   lhe
water very soon froze all around it;  however, the bean itself took
up a longer time in freezing  than the same quantity of water would
have  done; yet  it did freeze, and  was afterwards thawed  and
planted  in the  ground, but it  soon withered.   The same experi-
ment was  made upon the bulbous roots of tulips, and with the same
success.
  Experiment II. A young Scotch fir,  which had  two complete
shoots and a third  growing, and  which consequently wTas in its
third year, was put into the  cold mixture, which was between 15°
and 17°.   The last shoot froze with great difficulty, which appeared
to be owing in  some measure  to the repulsion between the plant
and the water.   When thawed the young shoot was found flaccid.
It was planted;  the  first and second shoot  we found retained life,
while the third, or growing  shoot, withered.
  Experiment III.  A young shoot of  growing  oats, with three
leaves, had one of the leaves put into the cold mixture at 22°, and
it soon was frozen.  The roots were next put in, but did not freeze;
and when put into the ground the whole grew, excepting the leaf
which had been frozen.   The  same experiment was  made upon
the leaves and roots of a young bean, and  attended with the same
success.
  Experiment IV. A leaf taken from a  growing bean was put into
the cold mixture and frozen, and afterwards thawed, which served
as a  standard.  Another fresh leaf was  taken  and  bent in the
middle upon itself; a small  shallow leaden  vessel was  put upon the
top of the cold mixture, and the two leaves put upon its bottom ;
but one half of each  leaf was not allowed to touch the vessel by the
bend: the cold mixture was between 17° and  15°, and the atmo-
sphere at  22°.   The surfaces of the two leaves which were in con-
tact with the lead were  soon  frozen  in both;  but  those surfaces
which rose at right angles, and were therefore only in contact with
the cold atmosphere, did not freeze in equal times;  the one that had
gone through this process before froze much sooner than the fresh
one.  The above experiment was repeated  when the cold  mixture
was at 25°, 24°,  and the atmosphere  nearly the same,  and with the
same success ;  only the  leaves were  longer in  freezing, especially
the fresh leaf.
   Experiment V.   The vegetable juices  above-mentioned being
frozen in the leaden vessel,  the cold  mixture at 28°, and the atmo-
sphere the same, a growing fir-shoot was  laid upon  the  surface,
also a bean-leaf; and  upon remaining  there  some minutes, they
were found to have  thawed the surface on which they lay.  This
 I thought might arise from  the greater warmth of these substances
 at the time of application ;  but by moving  the fir-shoot to another
part, we had the same effect produced. 
ON THE HEAT OF VEGETABLES.            179
   Experiment VI.   A fresh leaf of a bean  was exactly weighed ;
it was then put into the cold atmosphere and  frozen.   In this state
it was put back into the  same  scale, and  allowed to  thaw.  No
alteration in the weight was produced.
   From the  foregoing experiments  it appears, first, that  plants,
when in a state of actual vegetation, or even  in  such a state as to
be capable of vegetating under certain  circumstances, must be de-
prived of their principle of  vegetation before they can  be frozen.
Secondly, vegetables have a power within themselves of producing
or generating heat; but not always in proportion to the diminution
of heat by application of cold, so as to retain  at all times an uni-
form degree of heat; for the internal temperature of vegetables is
susceptible of variations to a much greater extent indeed than that
of the  more imperfect animals, but still  within certain  limits :  be-
yond these limits the principle of vegetable, as of animal life, resists
any further change. Thirdly, the heat of  vegetables  varies  ac-
cording to the temperature of the medium in which they are, which
we discover by varying that temperature, and observing the heat
of the  vegetable.  Fourthly, the expense of the vegetating powers
in this case is proportioned to the necessity,, and the whole vegetable
powers may be exhausted in this way.  Fifthly, this power is most
probably in proportion to  the perfection of the plant, the natural
heat proper to each species, and the age of  each  individual.   It
may also perhaps depend, in some degree, on  other circumstances
not hitherto observed ; for in Experiment II. the old shoot did not
lose its powers, while that which was young or growing did ; and
in Experiments II. and III. we found that the young growing shoot
of the fir was  with great difficulty frozen at  15°, while a bean-leaf
was easily  frozen at 22°; and in experiment V. the young shoot of
fir thawed the ice at 28° much faster  than  the leaf of the  bean.
Sixthly, it is probably by means of this principle  that  vegetables
are adapted to different  climates.  Seventhly, that suspension of
the functions of vegetable life, which takes place during the winter
season, is probably owing to their being susceptible of such a great
variation of internal temperature.  Eighthly, the roots of vegetables
are capable of resisting cold more than the stem or leaf;  therefore,
though the stem  be killed by cold, the  root  may  be preserved, as
daily experience evinces.   The texture of vegetables alters  very
much  by the  loss  of life, especially those which are watery and
young  ; from being brittle and crisp, they become tough  and  flexi-
ble.  The leaf of a bean when in full health  is thick  and mossy,
repels water as if greasy, and will often break  before it is consider-
ably bent;  but if it is killed slowly by  cold, it will  lose  all  these
properties,  becoming then pliable and flaccid : deprived of its power
of repelling water, it is easily made wet, and  appears like boiled
greens.  If killed quickly by being frozen immediately, it will re-
main in the same state as when alive ; but upon thawing, will im-
mediately lose all its former texture.   This  is  so  remarkable, that
it would induce one to believe that it lost considerably of its sub- 
180          HUNTER ON THE ANIMAL CECONOMY.
stance; but from  Experiment  VI. it is  evident that it does not.
The same thing happens to a plant when killed by electricity.*  If
a growing juicy plant receives  a stroke  of  electricity sufficient to
kill it, its leaves droop, and the whole becomes flexible.
   So far animal and vegetable life appear to be the  same;  yet  an
animal and a vegetable differ in one  very material  circumstance,
which  it may be proper to take  particular  notice of in this  place,
as it shows itself with  remarkable evidence  in these experiments.
An animal is equally old in all its parts, excepting where new parts
are formed in consequence of diseases ; and we find  that these new
or young parts  in animals, like the young shoots of vegetables, are
not able to support life  equally with the old ; but every plant has in
it a series of ages.  According  to  its  years, it has parts of all the
successive ages from its first formation;  each  part  having power
equal to its age, and each part, in this respect, being  similar  to ani-
mals of so many different ages.  Youth, in  all cases, is a state of
imperfection; for  we  find that  few animals  that come into the
world in winter live, unless  they  are  particularly taken care of;
and we may observe the same of vegetables.  I found that a young
plant was more easily  killed than an old one;  as also the youngest
part of the same plant.
   fAs I had formerly, in making my experiments  upon animals
relative to  heat and  cold, made  similar ones on vegetables, and
had  generally  found   a  great  similarity between them in these
respects, I was  led to pursue the subject on the same plan; but I
was still further induced to  continue  my experiments  upon vege-
tables, as I imagined I saw a material difference between them  in
their power  of supporting cold.
   From observations and the foregoing experiments, it plainly ap-
pears that the living principle will not allow the heat of such animals
to sink much lower than the freezing point,  although the surround-
ing atmosphere be much colder, and that in such a  state they
cannot support life long;  but it may be  observed, that most vege-
tables of every country can  sustain the  cold  of their climate.   In
very cold regions, as in the more northern parts of America, where the
thermometer is often 50° below 0, where people's feet are  known
to freeze and their noses to drop off" if  great care be not taken, yet
the spruce-fir, birch, juniper, &c, are not affected.
   Yet, that  vegetables can  be  affected  by cold, daily experience
evinces ; for the vegetables of  every  country are  affected if the
season be more than  ordinarily cold for that country, and some
more than others; for in the cold climates above  mentioned the
life of the vegetable is  often obliged to give  way to the cold of the
country: a tree shall die by the cold ; then freeze and split into a
great number of pieces"; and in so doing produce considerable noise,
giving loud  cracks, which are often heard at a great distance.

  * To kill a whole plant by electricity, it is  necessary to apply the conductor,
or give a shock to every projecting part;  for  any part that is  out of the line of
direction will  still retain life.
   | [See Phil. Trans.,lxviii.,  1778, p. 38.] 
ON THE  HEAT OF VEGETABLES.            181
   In  this country the same thing sometimes  happens to exotics
from  warmer climates.  A remarkable instance of this kind hap-
pened this winter in  His Majesty's garden at Kew.   The Erica
arborea, or  tree-heath, a native of Spain and  Portugal, which had
kept  its  health  extremely well  against a garden wall for four or
five years, though covered with a mat, was killed by the cold, and
then,  being frozen, split into innumerable  pieces.*  But the ques-
tion is, Is every tree dead  that is frozen ?  I  can only say, that in
all the experiments I ever  made upon trees and shrubs, whether in
the growing or active state, or in the passive, that whole or part
which was frozen was dead when thawed.
   The winter 1775-6 afforded a very favourable opportunity for
making  experiments relative to  cold, which  I  carefully availed
myself of.  However, previous  to that winter, I had made many
experiments  upon vegetables respecting  their temperature, com-
paratively with that of the  atmosphere, and wThen they were in their
different states of activity  : I therefore examined them in different
seasons,  with a  view to see what powers vegetables have.   I shall
relate these experiments in the  order in which they were made.
   They  were begun in the spring, the actions of life upon which
growth depends being then upon  the increase;  and they were con-
tinued till those  actions were upon  the decline, and also when all
actions were at  an end, but whilst the passive powers of life w7ere
still retained.
   The first  were made on a walnut-tree, nine feet high in the stem,
and seven feet in circumference in the middle.
   A hole was bored into it on the north  side, five feet above the
surface of the ground, eleven inches  deep towards the centre of
the tree, but  obliquely upwards, to allow any sap, which might
ooze through the wounded surface to run out.
   I then  fitted to this part  a box, about eight  inches wide and five
deep, and fastened it to the tree: the bottom of the box opened like
a door with a hinge.  I stuffed  the  box with wool, excepting the
middle, opposite to the hole in the tree ; for this part I had a plug
of wool  to stuff in, which, when  the  door was  shut, inclosed the
whole.   The intention of this was to keep off, as much as possible,
all immediate external influence either of heat or cold.
  The same thermometer  with which I  made my former experi-
ments, seven inches and a  half  long, was  sunk into a long feather
of a peacock's tail, with a slit upon  one side to show the degrees;

  * This  must be owing to the sap in the tree freezing, and occupying a larger
space when frozen than in a fluid state, similar to water;  and that there is a
sufficient quantity of sap in a tree newly killed, is proved by the vast quantity
that flows out on  wounding a tree.  But what appeared most  remarkable to
me was, that in a walnut-tree, on which I made many of my experiments, I ob-
served that more sap issued out in the winter than in the summer. In the sum-
mer, a hole being bored, scarcely any came  out, but in the winter it flowed out
abundantly.
                                17 
182          HUNTER ON THE ANIMAL CECONOMY.
by this means the ball of the thermometer could be introduced into
the bottom of the hole.                                    .  .
  Experiment 1.  March 29.  I began my experiments at  six in
the morning, the atmosphere at 57£°, the thermometer  in the tree
at 55°;  when  it was withdrawn the quicksilver sunk  to 53, but
soon rose to 575°.*
  This experiment was repeated three times with the same success.
Here the tree was cooler than the atmosphere, when one should
rather  have expected to find  it warmer, since it could not be sup-
posed to have as yet lost its former day's heat.
  Exp.  II. April  4th, half-past five in the evening.  The tree at
56°,  the atmosphere at 62°; the tree therefore still cooler than the
atmosphere.
  Exp.  III. April 5th.  Wind in the north, a  coldish  day, six
o'clock  in the evening; the  thermometer in the tree was at 55°, the
atmosphere at 47°; the tree warmer than the atmosphere.
  Exp.  IV. April 7th, a cold  day, wind in the north, cloudy.  At
three in the afternoon the thermometer in the tree was at 42°, the
atmosphere at 42° also.
  Exp.  V. April 9th, a cold day, with snow, hail, and wind in the
north-east.  At  six  in the evening the thermometer in the tree at
45°,  the atmosphere at 39°.
  Here the tree  was warmer than the atmosphere, just as might
have been expected.  If these experiments prove anything, it is that
there is  no standard ; and probably these variations arose from some
circumstance which had no immediate connexion with the internal
powers  of the tree; but it may also be  supposed  to  have arisen
from a power  in the tree to  produce or diminish heat, as some of
them were in opposition to the atmosphere.
  After having  endeavoured to find out  the comparative heat
between vegetables  and the atmosphere when the vegetables were
in action,  I next made my experiments upon them when they were
in the passive life.
  As the difference was very  little when in  their  most active state,
I could  expect but very little when the powers of the plant were at
rest.
   From experiment  upon the more imperfect classes of animals it
plainly  appears,  that although they do  not resist the effects of
extreme cold  till they are  brought to the freezing point, they then
appear  to have the power of  resisting it, and of not allowing their
cold to  be brought much lower.
   To  see how  far vegetables are similar  to those animals in this
respect, I made  several experiments:  I however  suspected them
not  to be  similar, because  such animals will die in  a cold in which
 vegetables do live;  I therefore supposed that there was some other
 principle.

   * The sinking of the quicksilver upon being withdrawn I imputed to the evapo-
  atino- of the moisture of the fluid upon the ball. 
ON THE HEAT OF VEGETABLES.
183
  I did not confine these experiments to the walnut-tree, but made
similar ones on several trees of different kinds, as pines, yews, pop-
lars, &c, to see what was the difference in different kinds of trees.
The difference proved not to be great, not above a degree or two :
however, this difference, although small, shows a principle in life, •
all  other things being equal;  for  as the same experiments were
made on a dead tree, which stood with its  roots in the ground,
similar to the living ones, they became more conclusive.
  In October I began the  experiments upon the walnut-tree when
its powers of action were on the decline,  and when it was going
into its passive life.
  Exp. VI. October 18th, at half-past six in the morning, the atmo-
sphere at 515°,  the thermometer  in the  tree  was at 55|°; but, on
withdrawing and exposing it for a few minutes in the  common
atmosphere, it fell to 5O30.
  Exp. VII. October 21st, seven  o'clock in the morning, the atmo-
sphere at 41°, the tree at 47°.
  Exp.  VIII.  October 21st, in  the evening at five  o'clock, the
atmosphere at 51^°, the tree at 57°.
  Exp. IX.  October 22d, at seven in the morning, the atmosphere
at 42°, the tree  at 48°.
  Exp. X. October 22d, one o'clock afternoon, the atmosphere at
51°, the  tree at 53°.
  Exp. XL  October 23d, in the  evening of a wet day, the atmo-
sphere at 46°, the tree at 48°.
  Exp. XII. October 28th, a dry day, the atmosphere at 45°, the
tree at 46°.
  Exp. XIII. October 29th, a fine day, the atmosphere at 45°, the
tree at 49°.
  Exp. XIV. November 2d, wind east, the atmosphere at 43°, the
tree at 43°.
  Exp. XV. November 5th, wet day, the  atmosphere at 43°, the
tree at 45°.
  Exp. XVI. November 10th.  Atmosphere at 49°, the tree at 55°.
  Exp. XVII.  November 18th. Atmosphere at 42°, the tree at 44°.
  Exp. XVIII. November  20th,  fine day,  the atmosphere at 40°,
the  tree  at 42°.
  Exp. XIX. December 2d. The atmosphere at 54°, the tree at 54°.
  In all  these experiments, which were  made at  various times in
the  day, viz., in the morning, at noon, and in the evening, the tree
was in some degree warmer than the atmosphere, excepting in one,
when their  temperatures were equal.  For  the sake of brevity,  I
have  drawn up my other experiments (which were made on dif-
ferent trees) into four tables, as they were  made at four  different
degrees  of heat of the atmosphere, including those made in the
time of  the  very hard frost in the  winter of 1775-6.  They were
as follows: 
184
HUNTER ON THE ANIMAL CECONOMY.
Table I.
	_-----------------------_----------,------------------.-----------------------------------------------------------,------------.---------------- ■						Dia-	
Atmosphere.	Names. j Height.						meter.	Heat.
						ft. in.	ft. in.	o
		fCaiolina poplar.....				2 0	0 2	29^
		English poplar			.	4 0	0 2J	29i
		Oriental plane			.	3 0	0 li	30
		Occidental plane .			,	3 6	0 2	30
		Carolina plane			m	1 0	0 1#	30
		Birch .			M	3 6	0 21	29$
59 deg.	<	Scotch fir Cedar of Lebanon . Arbutus Arbor vita? Deciduous cypress Lacker varnish			•	3 6 2 2 2 6 2 8 3 0 3 6	0 4 0 4i 0 U 0 n 0 2\ 0 2	28$ 28i 30 29 30 30
	^.Walnut-tree .				•	5 0	2 4	31
  The old hole in the walnut tree, being full of sap, was frozen up;
but a new one was made.
	T	ABLE	II.				
						Dia-	
Atmosphere. Names.					Height.	meter.	Heat.
					ft. in.	in.	o
	f Spruce fir.....				4 0	n	32 28
	Scotch fir .				1 h\	H	
	Silver fir .				3 11	2^	30
	Weymouth fir .				4 6	h	30 30
27 deg. <<	Yew				3 7	3	
	Holly				2 6	2	30
	Plum-tree .				4 6	3	3l£
	Dead cedar				3 11	3	29
	^Ground under snojv				0 3 deep.	" '	34
Tabu III.
Atmosphere.	Names.	Heat.
	f Spruce fir .... I Scotch fir ....	o 23 23
	1 Silver fir ....	23
24 deg.	<( Weymouth fir . Yew	23 22
	1 Holly..... UDead cedar ....	23 24
  The same trees we mentioned when the thermometer was at 29°,
in new holes made at the same height, and left some  time  pegged
up till the heat produced by the gimlet was gone off;  but in which,
as they were  moist from the sap, the  heat  could be very  little,
especially as the gimlet was not in the least  heated by the opera-
tion. 
OF PERSONS APPARENTLY DROWNED.

              Table IV.
185
Atmosphere. Names.		Heat.
16 deg. <	'Carolina poplar English poplar Oriental plane Occidental plane . . Carolina plane . . Birch..... JScotch fir	o 17 17 17 17 17 17 . . 16£
  It will be necessary to observe, that the sap of the walnut-tree,
which- flowed out in great quantity, froze at 32°.  I did  not try to
freeze the sap of the others.
  Now since the sap of a tree when taken out freezes at  32°; also,
since  the sap of a tree, when taken out of its proper canals, freezes
when the heat of the tree is at 31°;  and since the heat of the tree
can be  so low as 17°, without freezing; by  what power  are  the
juices of the tree,  when in their proper canals, kept fluid  in such a
cold 1  Is it the principle  of vegetation 1  Or  is the sap inclosed in
such  a  way as that the  process  of freezing cannot take place,
which we find to be the case when water is  confined in globular
vessels ?   If so,  its confinement  must be  very different from  the
confinement of moisture in dead vegetables ; but the circumstance
of vegetables dying  with the cold  and  then freezing appears to
answer the last question.  These, however, are questions which at
present I shall not endeavour to solve.
  I have made several experiments  upon  the seeds of  vegetables
similar to those on the eggs of animals; but as inserting them would
draw out this paper to too great a length, I will  reserve them for
another.
16. PROPOSALS  FOR  THE  RECOVERY OF  PERSONS
               APPARENTLY DROWNED.*

  Having been requested by a principal member of the society
established for the recovery of persons apparently drowned to com-
mit my thoughts  on that subject  to  paper, I readily complied,
hoping, that although I have had no opportunities of making actual
experiments  upon  drowned persons, it  might be in my power to
throw some lights on a 'subject so closely connected with the inqui-
ries which for many years have been  my business and favourite
amusement:  I therefore collected together  my  observations and
experiments relative to the loss and  recovery of the actions of life,
which I now  offer to the public.   The  endeavour to  recover per-
* rFrom the Philosophical Transactions, vol. lxvi.; read March 21, 1776.]
                           17* 
186          HUNTER ON THE ANIMAL CECONOMY.
sons apparently drowned is  a new practice, and has furnished, as
yet, few important and  clear facts: our knowledge of the animal
ceconomy is so imperfect, that I am afraid our reasoning from that
alone must not be relied on in a question so interesting to the cause
of humanity.  But let us reason as well as we can from  the few
data we have, and let every man bring forward, freely, the obser-
vations  he  has  made,  that the subject thus  fairly  before  the
public may in time, by its united efforts, be more  perfectly under-
stood.
  I shall consider  an animal apparently  drowned as not dead, but
that only a suspension of the actions of life has taken place.   The
difference between a suspension of the actions of  life and  absolute
death is well illustrated by the common snail when drowning.  If a
snail is immersed in water and  kept there, certain voluntary and
instinctive actions  take place; but  after  remaining a certain  time
covered by the water, all these actions  cease.   Hence the animal,
being relaxed, naturally comes  out of the shell  in that state;  its
stomach  is  filled  with water, and the body  appears larger  than
natural, but without motion.  These actions continue thus suspend-
ed till either the cause of suspension be  removed or some  other
stimulus  shall bring the parts into  action : but under such circum-
stances life cannot be preserved for any considerable length of time;
and when the stimulus which precedes death takes place, the whole
animal is thrown into action, and in that contracted state, possibly,
absolute  death is produced.  A state of relaxation should therefore
(where an universal violence has not been  committed), be considered
as the criterion of  life; and even in such cases should be for some
time admitted as a probable  reason for supposing life still to exist.
  If an animal appears  so far dead as to have lost all the actions
characteristic of life, yet a certain  degree of action in all the parts
will be produced when absolute death  is taking  place;  and that
animal, being still susceptible of stimulus, is  recoverable if the
proper stimulus could be applied.
  It is asserted  that men have  recovered the actions of life even
after the  contraction, in consequence of the stimulus which pre-
cedes death, has taken place.  If this be  true, which I very much
doubt, the stimulus must first produce relaxation, which is an action
dependent on life.
   This is probably the case in the first appearances of death from
all violent  accidents, except those caused by lightning, electricity,
an universal shock,  a blow on the stomach, a violent affection of
the mind, or some other modes by which absolute death may be
instantaneously produced, which all appear to act in the same way,
producing absolute and instant  death.   For in cases which  have
fallen under  my observation, the concomitant circumstances have
 resembled those which attend death caused by lightning or electri-
 city, such as a total and instantaneous privation  of sense and mo-
 tion without'convulsions; consequently, no rigor of muscles having
 been produced, and the blood  remaining uncoagulated,  differing 
OF  PERSONS APPARENTLY DROWNED.
187
entirely in these  respects from what appears in persons  deprived
of sense and life by any injury done the brain.  It seems  only
possible to account for this effect of a blow on the stomach,  from
the connexion subsisting between that viscus and every part of the
body,  at  least with vital parts;  the blow  most  probably causing
instant death in that organ of which the death of the  whole animal
is the consequence.* When death takes place from violent affections
of the mind, it must be referred to the universal influence which the
mind has over the body.
   To  ascertain when a body is deprived of life it is first necessary
to know in what  manner  apparent death  took place; whether in
the common way, or from the vital actions being too long suspended.
In either case stiffness of the muscles is  probably the most certain
and most evident proof of absolute death, since that arises  from
the stimulus immediately preceding death, having taken place.   But
if the privation of life is produced by any of the modes above  men-
tioned, which kill  instantaneously and universally, the stimulus which
produces stiffness is not allowed time to  act, and  the muscles are
all left in a relaxed state.  Yet this state of relaxation must not, on
that account, be always considered as a proof of life still remaining.
   A degree  of flaccidity in the eyeballs, which produces glassiness,
is a certain  mark of death ; but is, however, only a secondary mode
of ascertaining it in those instances where  the body becomes  stiff;
but may be  the first mode  where absolute death takes place instan-
taneously ;  and putrefaction  will  be the  second ;  while in the  other
cases putrefaction will  be the third.
   That I may more fully: explain my ideas upon this subject, it will
be  necessary to state some propositions.
   First;  that so  long as the animal retains the  susceptibility of im-
pression, though deprived of the action of life, it will, most  probably,
retain the power of action when  impressed; therefore the action
may frequently be suspended, and  yet recoverable;  but  when the
susceptibility of impression is destroyed, the action ceases to be re-
coverable.   Secondly; it  is necessary to mention, that I consider
part of the living  principle as inherent in the blood.f   Thirdly ; that
the  stomach sympathizes with every part of an animal, and that

   * I should consider the situation of a person drowned to be similar to that of a
person in a trance.   In both the action of life  is suspended without the power
being destroyed ; but I am inclined to believe that a greater proportion of persons
recover from trances than from drowning, because a trance is the natural effect  of
a disposition in the person to have the  action of life suspended for a time; but
drowning being produced by violence,  the suspension will more frequently last
for ever, unless the power of life is roused to action by some  applications of art.
  f That the living principle is  inherent in the blood  is a doctrine which the
nature of this account will not allow me to discuss; thus much, however,  it may
be proper to say, that it is founded on the result of many observations and expe-
riments.  But it  may be thought necessary I should here  give a definition  of
what I call the living principle: so far, then, as I have used the term, I mean  to
 express that principle which preserves the body from dissolution with or without
 action, and is the cause of all its actions. 
]88          HUNTER ON THE ANIMAL CECONOMY.
every part sympathizes with the stomach ; therefore, whatever acts
upon the stomach  as a  cordial, or rouses its natural and  healthy
actions, and whatever affects  it so as  to produce debility, has an
immediate effect upon every part of the body.  The last proposition
I have to make is, that every part of the body sympathizes with the
mind;  for whatever affects  the mind, the body is affected in pro-
portion.   These sympathies are strongest with the vital parts; but
besides these universal sympathies between  the stomach, the  mind,
and all parts of the body, there are  peculiar sympathies, of which
the heart, sympathizing  immediately  with the lungs, is  an instance.
If anything is received  into the lungs which is a poison to animal
life, such as inflammable air, volatile vitriolic acid, and many other
well-known substances,  the motion of the heart immediately ceases,
even much sooner than  if the trachea had been tied ; and, from ex-
periments, it appears  that anything salutary to life, applied  to the
lungs,  will restore the heart's  action  after it has  been at rest some
time.
  I shall divide violent deaths into three  kinds ; first, where a stop
is put only to the action of life in the animal, but without any irre-
parable injury to a vital part, which action, if not restored  in  a
certain time, will be irrecoverably lost.   The length of that time is
subject to considerable variation,  depending on circumstances with
which we are at present unacquainted.  The second is, where an
injury is done  to  a vital part, as by  taking away blood  till the
powers of action are  lost;  or  by a wound or pressure being made
on the brain or spinal  marrow while  life remains  in the solids suffi-
cient for the preservation of the animal, if. action  could be restored
to the vital parts. The third is, where absolute death  instantly
takes place in every part, as  is  often the case in strokes of lightning;
in the common method  of  killing eels, by throwing them  on some
hard substance, in  such manner  as  that the whole length of the
animal shall receive the shock at the same instant; by a blow on
the stomach; by  violent  affections  of the mind; and  by  many
diseases, in all which  cases the muscles remain flexible.*
  How far that may be  strictly considered as a violent death which
is caused by affections of the  mind,  I will not pretend to say; but
if it is to have  a place in that class, it must be ranked with those
which happen from lightning,  and a  blow on the  stomach; and in
most cases of persons drowned, I can  easily conceive the  mind to
be so  much  affected prior to the immersion,  and in the moment im-
mediately succeeding it, as  to make a material  difference in the
power of recovery.  In many sudden deaths arising from violence,
and even from  disease,  death  shall take place so immediately that
the muscles neither contract, nor does the blood coagulate.

  * On the other hand, when an eel is killed by chopping it into a number of
pieces, the powers of life are by those means roused into  action ; and as every
part dies in that active state, every part is found stiff after death.  This explains
the custom of cutting fish into pieces while yet alive, in order to make them hard,
 usually known by the name  of crimping. 
OF PERSONS APPARENTLY DROWNED.
189
  The present consideration is, under which of the kinds of violent
death drowning can  be classed or arranged?   I am of  opinion it
will most  commonly come under the first, and upon that ground I
shall principally consider the subject,  always supposing the body to
remain flaccid.
  The loss of motion in drowning seems  to arise from the loss of
respiration, and the immediate effects which that has upon the other
vita] motions of the animal; except what may have arisen from the
affections  of the mind.   The privation of  breathing appears, how-
ever, to be the first cause, and the heart's motion ceasing, to be the
second  or consequent; therefore most  probably the restoration of
breathing  is all that is necessary to restore the heart's motion; for
if sufficient life  still  exists to produce that effect, we may suppose
every part equally ready to move  the very instant in which the
action of  the heart takes  place, their actions  depending so  much
upon it.   What makes it very probable, that in recovering persons
drowned,  the principal effect  depends upon air being thrown into
the lungs,  is what happens at the birth of children, when too  much
time has  intervened  between the interruption of that  life which is
peculiar to the foetus and that which depends  on breathing;  they
then lose  altogether the  disposition for this new life; and in such
cases, there being a  total suspension  of the actions of life, the child
remains to all appearance dead, and would certainly die if air were
not thrown into  its lungs, and by such means the first principle of
action restored.  To put this in a still clearer light, I will give the
result of some experiments which I  made  in the year  1755 upon a
dog.
  A pair  of double bellows were provided, constructed  in such a
manner as by one action to throw fresh air into the lungs, ana by
another to suck out again the air which had been thrown in by the
former, without mixing them together.  The muzzle of these bellows
was fixed into the  trachea of a dog, and by working them he was
kept perfectly alive.   While  this artificial breathing was going on
I took off the sternum of the dog,and exposed  the lungs and heart;
the heart  continued to act as before, only the frequency of its action
was considerably  increased.  When I  stopped the motion of the
bellows the heart  became gradually weaker, and  less frequent in
its contractions, till it entirely ceased to move.  By renewing the
action of  the bellows the heart  again began to move, at first very
faintly, and with long intermissions ;  but by continuing the artificial
breathing, its motion became  as frequent and as strong  as at first.
This process I repeated upon the same dog ten times, sometimes
stopping for five, eight, or ten minutes, and observed that  every
time I left off working the bellows  the heart became  extremely
turgid with blood,  the blood in the  left side becoming as dark as
that in the right, which was not the case when the bellows were
working.   These situations of the animal appeared to me exactly
similar to drowning.
  Death in persons drowned has been accounted for by supposing 
190          HUNTER ON THE ANIMAL CECONOMY.
that the blood, rendered unfit for the purposes of life by being de-
prived of the action of the  air  in  respiration, is sent in a vitiated
state to the brain and other  vital parts, by which means the nerves
lose their effect upon the heart,  and the  heart in  consequence its
motion.  This, however, I am fully convinced  is false ; first, from
the experiments  on the dog, in which a large column of blood so
vitiated (consisting of what had been propelled from the  heart after
respiration stopped, and might be supposed the cause of the heart
ceasing to act, together with all that remained in  the heart and
pulmonary veins), was again pushed forward without any ill effect
having been produced; and  next, from the  return to  life of persons
drowned and children still-born, which, were such  a  supposition
true, could never happen, unless we imagine a change of the blood
to take place in  the  brain, prior to the  restoration of  the heart's
motion.  This restoration must therefore  depend immediately on
the application of air to the  lungs, and not  on the effects which air
has upon the blood, or that blood upon the  vital parts.
  If the affections of the mind have had any share in the cessation
of action in the heart, its motion will not  be so easily  restored as
in other cases.   In our attempts to recover those who have been
drowned, it might therefore  be proper to inquire if there had been
time  sufficient for the person  to form  any idea  of his  situation
previous to  his  being plunged into the water, as it  is not  unlikely
that the agitated state of mind might assist in killing him;  and in
such case I  should very much  doubt the  probability of restoring
him to life.   In the history  of those who have  and who have not
been recovered, could the difference be ascribed to.any such cause,
it might lead to  something  useful;  as in  those who have had an
intention to destroy themselves, a great difference in the chance of
reeovery may arise, from the  mind having been previously very
much affected.
  It frequently happens, in  the  case of drowning, that assistance
cannot be procured  till  a  considerable  time after  the accident;
every moment of this delay renders recovery more precarious, the
chances of which are not only diminished in the parts where the
first powers of action principally reside, but  also  in every other
part of the body.
  In  offering my sentiments  on the method of treating  persons
who are apparently drowned, I shall say, first, what I would  re-
commend to have done ;  secondly, what I would wish  might be
avoided.
  When assistance is called in soon after  the immersion, perhaps
blowing air into  the lungs may be sufficient to effect a  recovery ;*
but if a considerable time, as an hour, has  been lost, it will seldom
be sufficient,  the heart in all probability  having by that time lost its

  * Perhaps the dephlogisticated air described by Dr. Priestly  (oxygen  gas)
may prove more efficacious than common air.  It is easily procured, and may be
preserved in bottles or bladders for that purpose. 
OF PERSONS APPARENTLY DROWNED.          191
intimate connexion with the lungs.   It will in these cases, there-
fore, be proper to apply, mixed with the air, such stimulating medi-
cines as the vapour of volatile alkali, which may easily be done, by
holding spirits of hartshorn in'a  cup under the receiver of the bel-
lows.  I would advise the air and volatile alkali to be thrown in by
the nose rather than the mouth, as the last mode of  administering,
by producing sickness, is more likely to depress than rouse the living
principle.  It will be  still better if it  can be done by both nostrils,
as applications of this kind to the  olfactory nerves certainly rouse
the living principle and  put the muscles of respiration into action,
and therefore are the more likely to excite the action of the heart:
besides, that affections of these nerves are known to act more im-
mediately on the  living principle; since while a strong smell  of
very sweet flowers, as orange flowers, will in many cause fainting,
the application of vinegar will as  immediately restore the powers
to action again.  All  perfumes in which there is some acid rather
rouse than depress, as the sweet-brier, essence of lemon, &c.   If,
during the operation of the bellows,  the larynx be gently pressed
against the oesophagus and spine, it will prevent the stomach and in-
testines being too much distended by the air, and leave room for the
application of more effectual stimuli to those parts.  This pressure,
however, must be  conducted with judgment and caution, so  that
the trachea and the aperture into the larynx may both be left per-
fectly free. • While  this business is going on an  assistant should
prepare bedclothes, carefully brought to the proper degree of  heat.
I consider heat as congenial with  the  living principle;  increasing
the necessity of action, it increases  action ; cold, on the other hand,
lessens the necessity, and of course the action is  diminished :  to a
due proportion  of  heat, therefore, the living  principle owes its
vigour; and, from observations and experiments, it appears to be a
law of Nature in animal bodies, that  the degree of  external heat
should bear a proportion to the quantity of  life;  when it is weak-
ened, this proportion  requires great  accuracy in the adjustment,
while greater powers of life allow a greater latitude.*
  I was led to make  these  observations  by attending to  persons
who are frost-bitten, the effect of cold in such  cases  being that  of
lessening  the  living principle.   The  powers of action remain  as
perfect as ever, but weakened, and heat  is the only thing wanting
to put these powers into action : yet that heat must at  first be gradu-
ally applied, and proportioned to the quantity of the living principle,
which increasing, the degree of heat may likewise be increased.  If
this method is not observed, and too great a degree  of heat is  at
first applied, the person or part loses  entirely the living  principle,
and mortification ensues.  Such a  process invariably takes place

  * It is upon these principles that cold air is  found of so much  service to people
who are reduced by disease, as the confluent small-pox and fevers, by diminish-
ing heat in proportion to the diminution of life, or lessening the necessity of the
body's producing its own cold. 
192          HUNTER ON THE ANIMAL CECONOMY.
with regard to men, and the same thing, I am  convinced, happens
to other animals.   For if an eel is exposed to a degree of cold sufl>
ciently intense to benumb it till the remains of life are scarcely per-
ceptible, and  still retained  in a cokTof about 40°, this small pro-
portion of living principle  will continue  for  a considerable  time
without diminution or increase; but if the animal is  afterwards
placed in a heat about 60°,  after showing strong signs of returning
life, it will die in a few minutes.  Nor is this circumstance peculiar
to the diminution of life by cold.  The same phenomena take place
in animals which have been very much reduced by hunger.
  If a lizard  or snake, when it goes to its autumnal hiding-place,
is not sufficiently fat, the living powers are, before the season per-
mits it to come out, very considerably weakened ;  perhaps so much
as not to admit of the animal being again restored.  If animals in
a torpid state are exposed to the sun's rays, or placed in any situa-
tion which  by its warmth would give vigour to those of the same
kind possessed of a larger share of life, they will immediately show
signs of increased life, but quickly sink under the  experiment and
die; while  others, reduced  to the same degree of  weakness, as far
as appearances can discover, will  live for many weeks, if kept in
a degree of cold proportioned to the quantity of life they possess.
  I observed, many years ago, in some of the colder parts of this
island, that when intense cold had forced blackbirds or thrushes to
take shelter in outhouses, such of them  as had been caught, and
were, from an ill-judged compassion, exposed to a  considerable
degree of warmth, died very  soon.  The reason of this I did not
then understand; but  I  am now satisfied that it was owing, as in
other instances, to  the degree of heat being increased too suddenly
for the proportion of life remaining in the animal.
  From these facts it appears that warmth causes a greater exertion
of the living powers than cold; and  that  an animal in a  weakly
state may be  obliged  by it  to exert a quantity  of  the action of life
sufficient to destroy  the very  powers  themselves.*   The same
effects probably take place  even in perfect health;  it appearing,
from  experiments made in a heated  room, that a person in  health,
exposed to  a  great degree of heat, found the actions of life  accele-
rated so much as to produce at last faintness and debility.f
  If bedclothes are put over the drowned person,  so as scarcely to
touch him,  steam of volatile alkali, or of warm balsams and essen-
tial oils, may be so conveyed as to come in  contact  with many
parts of his body;  and it will certainly prove advantageous if the
same kind of steams  can be conveyed  into the stomach,  as that
seat of universal sympathy will be  roused by such means.  This
may be done by a  hollow bougie and a syringe;  but the operation
should be  performed with  all possible  expedition,  because the
instrument, by continuing in  the mouth, may produce sickness, an

  * It is upon this principle that parts mortify in consequence of inflammation.
  + Vide Phil. Trans, for the year  1775, vol. Ixv., p. 111. 
OF PERSONS APPARENTLY DROWNED.
193
effect I should choose to avoid, unless it is intended to produce the
action  of vomiting.   Some of the  stimulating substances, which
are of a warm  nature  and  have an immediate effect, as spirits of
hartshorn,  peppermint-water,  juice  of horse-radish,  and  many
others which produce a more  lasting stimulus in a fluid state, and
are found to quicken the pulse of a man in health, as balsams and
turpentines, may be  thrown into  the  stomach; but the  quantity
must be small, as they have a  tendency to produce sickness;  for it
may be imagined that what would produce debility, or lessen action
when in health,  would  in  opposite circumstances  prevent actions
from taking place.   The application of steams and  other substances
should  also  be  thrown up by the anus; and the  process recom-
mended under the first  head of treatment should still be continued
while  that  recommended under the second  is putting in practice,
the last being  only  an auxiliary to  the first.  The first, in many
cases,  may succeed alone; but the second without  the first must, I
think,   always  fail  where the powers of  life are considerably
weakened.   Motion may possibly be of service, it  may at least be
tried;  but, as it has  less effect than any other of the usually pre-
scribed stimuli,  it should be the last applied.*   I would recommend
to the  operator the same care in regulating the application of every
one of these methods as I  did  before in that  of heat, as each may
have the same properly  of entirely destroying the feeble action
which  they have excited, if administered in too great a proportion.
Instead, therefore, of increasing  and  hastening the operations on
the first signs of returning life  being observed, as is usually done, I
should   wish them  to be  applied more gently and gradually, that
their increase afterwards may  be directed, as nearly as possible, in
a degree proportioned to the powers as they arise.  • As the heart is
commonly the last part  that  ceases to act, it is probably the first
part that takes on the action of recovery.  When it begins to move,
I would advise  lessening  the  application  of air to the lungs, and
enjoin  those employed  to observe with great attention  when the
muscles of  respiration  begin  to  act, that our endeavours  may not
interfere with their  natural exertions, yet that  we may be still ready
to assist.  I would  by all means  discourage  bloodletting,  which I
think weakens  the  animal principle  and  life  itself, consequently
lessens  both the powers  and  dispositions to  action; and I would
advise   being careful not  to  call  forth any disposition that might
depress, by introducing things  into the stomach which ordinarily
create  nausea ; as that  also will have a similar effect, except it can
be carried so far as to excite the action of vomiting, by which the
stomach could relieve itself.   It will  be prudent likewise  to avoid

  * Electricity has been known to be of service, and should be tried when other
methods have failed.  It is probably the only  method  we have of immediately
stimulating the heart;  all other methods being more by sympathy. I have not
mentioned injecting stimulating substances directly into the veins, though it
might be supposed a proper expedient, because, in looking over my experiments
on that subject, I found none where animal life received increase by that method.
                               18 
194         HUNTER ON THE ANIMAL CECONOMY.
administering by the anus anything that may be likely to produce
an evacuation that way, every such evacuation tending to lessen
the animal powers.  I have purposely avoided speaking of the
fumes  of  tobacco, which  always produce  sickness or  purging,
according as they are applied.
  Whoever is appointed for  the  purpose  of recovering drowned
persons should have an assistant well acquainted with the methods
intended  to  be made use of; that while the one is going on with
the first and most simple methods, the other may be preparing what
else may be proper, so that no time may be lost between the opera-
tions ;  and this is the more necessary, as the first means recom-
mended will, in all cases, assist the second ; and both together may
often be attended with success, though each separately might have
failed.
  A proper  apparatus  is also  essentially necessary to the institu-
tion : a description of which I here annex.   First, a pair of bellows,
so contrived, with two  separate cavities, that  by expanding them,
when applied to the nostrils or mouth of a patient, one cavity may
be filled with the common air, and the other with  air sucked out
from the  lungs ;  and  by shutting them again, the common air may
be thrown into the lungs, and that which is sucked out of the lungs
be discharged into the room.  The pipe of these should be flexible,
in length a foot or a foot and a half, and  at least  three eighths  of
an inch in width: as the artificial breathing may be continued by
such means, while the other operations, except the application of
the stimuli to the stomach, are going on ; which cannot conveniently
be done if the nozzle of the bellows  be  introduced into the nose.
The end  next the nose should be double, and applied to both nos-
trils.  Secondly,-a syringe, with a hollow bougie, or flexible catheter,
of sufficient length to go into the  stomach, and convey any stimu-
lating  matter into it,  without affecting the lungs.  Thirdly, a small
pair of bellows, such as are commonly used in throwing fumes of
tobacco  up the  anus, by which  stimulating fluids or even fumes
may be thrown in.
   I shall conclude this account by proposing that all who are em-
ployed in this practice be particularly required to keep an accurate
journal of the means used, and the degree of success  attending
them; whence we may be furnished with facts sufficient to enable
us to draw conclusions, on which a certain  practice may hereafter
be established.
17. AN  ACCOUNT  OF CERTAIN RECEPTACLES OF AIR
    IN  BIRDS,  WHICH   COMMUNICATE  WITH  THE
    LUNGS AND EUSTACHIAN  TUBE.

  Since the  account of these receptacles was read before the Royal
Society, in the year 1774, I have, by the dissection of a number of
birds, been able to  make some additional  observations relative to 
OF AIR-CELLS IN  BIRDS.
195
the extent of the air-cells which  communicate with the  lungs in
animals of this class.   These latter observations were not, however,
made in consequence of any regular  design to investigate this sub-
ject further, as to have established the principle seemedall that was
necessary;  unless by general observations we  could hope to throw
more light  on  the final intention  of this remarkable piece  of
mechanism.
   Before  the period I  have mentioned, the communication  subsist-
ing in birds, between  the air-cells of the lungs  and  other  cavities
of the body, had not been clearly explained, nor even much attended
to  by  anatomists or  natural  historians.*  It  is  a singularity of
structure  peculiar to this tribe of animals; and on account  of it
cannot, I  imagine, be  unacceptable to the public.
   It  is not my present intention to enter into minute descriptions of
all the particular communications of this sort discoverable in birds
by dissection, but only to mention such general facts as  may serve
to introduce the subject into natural history, and lead to  an inquiry
into the purposes which this structure was  intended to  answer.
With this view I shall  endeavour to give some idea  of the  con-
struction  of the lungs, and of the air-receptacles in birds, occasion-
ally remarking the  circumstances in which these principally differ
from what is seen in other animals.
   The mechanism  of the lungs in birds, which renders them fit  for

   * [The continuation of the air-passages of the  lungs into  large  membranous
receptacles, situated in the abdominal cavity, was first discovered and  described
by Harvey (On Generation, 8vo., 1663, p. 7;  Opera Omnia, 4to., 1766, p. 185).
The abdominal air-cells of the ostrich are figured in Perault's Collection of Ana-
tomical Memoirs of the French Academicians.  Borelli, in explaining the causes
of the greater specific levity of birds,  observes, " Hoc patet, quia ossa avium
fistulosa, valde excavata et subtilia sunt, ad instar radicum pennarum scapulae,
costas et brachia parum carnosa sunt; pectus  et  abdomen amplas cavitates aere
plenas habent; pennae  tamen  et plumoe levissimse sunt."  (De Motu Animalium,
4to., 1685,  p. 231, prop. 194.)  Borelli appears, however, to have believed both
the quills of the feathers  and the hollow bones  to have contained only a light
marrow.  The discovery that the bones of birds contained air was first published
in the year  1774,—in England in the Philosophical Transactions  of that year,
which contained Mr.  Hunter's ' Account,' &c,  read before the Royal Society,
February 27, 1774; and in Holland  in the Verhandelirig van Bataafsche Genoot-
schte,  Rotterdam, 1774, in which Camper's discovery of the same structure was
first published.  Camper  transmitted, in the  year  1773, an account  of his  re-
searches on the air-bones of birds to  the French Academy, which was published
in the Mimoires de Mathematiques et  Physique, 4to., in 1776.  Whilst, therefore,
we may be willing to admit that  Camper's Memoir was founded on an indepen-
dent discovery, we must also conclude that the mass of valuable observations on
the air-receptacles  of  birds, communicated to the  Royal Society some months
before the first publication of Camper's discovery in  the Dutch language, was
equally original.  The  French translator of Carus's Comparative  Anatomy, in
a prefatory sketch of the History of  the Science, introduces John Hunter to  the
reader's notice as follows:  "Le premier, il (Camper) a fait remarquer que les
os longs du squelette des Oiseaux sont creuses de cavites dans  lesquelles l'air
a la facilite de s'introduire, parce qu'elles communiquent avec l'organe pulmo-
naire, decouverte que Hunter eut Pimpudeur de s'approprier quelques annees
apres."  (Jourdan's Carus, torn,  i., p. xxxi.) Truly the ignorance of such an
assertion can only be equalled by its impudence.); 
 196          HUNTER ON THE ANIMAL CECONOMY.

 conveying air to different parts of the body, consists principally in
 certain communications.
   It has been asserted that birds  have no  diaphragm ;  but  this
 opinion must  have arisen  either from  a want of  observation, or
 from too confined an idea of a diaphragm ; for there is a moderately
 strong, but thin and transparent membrane,  covering the lower
 surface of the lungs, and adhering to them, that affords insertion to
 several thin muscles which arise from the inner surfaces of the ribs.
 The use of this part seems to be that of lessening  the  concavity of
 the lungs  towards the abdomen  at the time of inspiration,  and
 thereby assisting to dilate the air-cells, for which reason it is to be
 considered as  answering one main purpose of a diaphragm.  Be-
 sides this attachment of the lungs to the diaphragm, they are also
 connected to the ribs, and to the sides of the vertebra?.*
   Such adhesions are peculiar to this tribe of animals, and  are of
 singular use, nay, in fact are absolutely necessary in lungs like those
 of birds, out of which it is  intended  the air should  find a passage
 into other cavities.  For if the  lungs were  loose  in the  cavity of
 the thorax, as  is the case in many other animals, the cells of the
 lungs could not be expanded, either by  the  depression of the dia-
phragm, or the elevation of the  ribs; since the air rushing in to fill
 up the  vacuum produced in the  cavity of the chest by these actions
 would  take the straight road from the trachea through the passages,
 and of consequence would  expand no part  of the lungs  which lay
out of that line, whereby respiration would be totally prevented,
and an effect produced exactly  similar  to what happens in other
animals when  the lungs are so much wounded as to allow a free
exit to  the air  in that part.f
   The  cells in the bodies of birds which receive air  from-the lungs
are to be found both in the soft  parts and in the bones, and have no
communication with the cavity  of the common cellular membrane.
Some of these air-bags  are placed in the larger cavities, as in the
abdomen; and others are so lodged  in  the  interstices of muscles,
blood-vessels, and nerves, about  the breast, axilla, &c, as at first to
give the appearance of the common  connecting membrane.   Some
communicate immediately with  one  another, and  all may be said
to have a communication by means of the lungs.  They are of very
different sizes, as may best suit the particular circumstances  of the
parts in which they are placed.
  The  bones which receive air  are of two kinds; some, as  the
sternum, ribs, and vertebras, having  their internal substance divided
into innumerable cells; whilst others,as the os humeri  and os femoris,
 are hollowed out into one large  canal, with sometimes a few bony
 columns running across at its extremities.  Bones  of this kind may
be distinguished from those that  do not receive air by  several marks :
 first, by their less specific gravity; secondly, by being less vascular
 than the others, and therefore whiter;  thirdly,"by their containing
* [See Harvey, on Generation, p. 6.]
t [Ibid., p. 7.] 
OF AIR-CELLS IN BIRDS.
197
little or no oil, and consequently being  more easily cleaned, and
when cleaned, appearing much whiter than common bones; fourthly,
by having no marrow, or even any bloody pulpy substance in their
cells;  fifthly, by not being in general so hard and  firm as "other
bones ;*  and sixthly, by the passage that allows the air to enter the
bones, which can be easily perceived.  In the recent bone we may
readily discover holes or openings not filled with any soft substance,
as blood-vessels or nerves; several of these holes are placed together,
near that end of the bone which is next to the trunk of the bird, and
are distinguishable by having their external edges rounded off, which
is not the case with the holes through which either nerves or blood-
vessels pass into the substance of the bone.   When birds break any
of the bones which contain air, the surrounding parts often become
emphysematous.
  There are openings in the lungs by which air is transmitted to the
other parts; and the membrane or diaphragm above-mentioned is
perforated in several places with holes of a considerable size, which
admit of a free communication between  the cells  of the lungs and
the abdomen, a circumstance  which  has been frequently noticed.
To each of these perforations  is joined a distinct membranous bag,
extremely thin and transparent, which bags being  afterwards con-
tinued through the whole of the abdomen, and attached to the back
and sides of that  cavity, are kept firm in their  proper situations,
each receiving the air from their respective openings.  There is no
occasion to  describe here  all  the bags, or their  attachments,  it
being  sufficient  to  have  said that  they extend  over the  whole
abdomen.
   The lungs at the anterior part, contiguous to the  sternum, have
openings into certain membranous cells which lie upon the sides  of
the pericardium, and communicate with  the cells  of the sternum,
At the superior part the lungs have a communication with the large
cells of a loose network, through which the trachea, cssophagus.
and great vessels pass as they are  going to and from the  heart.
When these cells are distended with air, the size of that part where
they lie is very considerably increased, and  this enlargement is  in
general a mark of either the passion of anger or love.  It is plainly
seen in the turkey-cock,'the pouting-pigeon,  &c, and is very visible
in the  breast of a goose when  she cackles.   These cells communi-
cate with others in the axilla,  under the large pectoral  muscle, and
in some birds are still further extended.  In the pelican,  for instance,
the skin  of the whole body, even to the tip of the wing, is united  to
the part underneath  by means of these cells, which  are  equally
formed; and when the skin is removed, the two separated surfaces
appear as if honeycombed.  When the cells are distended the skin
is  removed to a considerable distance, by which means the volume

  * The bones of some birds are so soft that they can be squeezed together
with the finger and thumb; the bones of the extremities, however, have very
solid sides.
                               18* 
198
HUNTER ON THE ANIMAL CECONOMY.
is proportionally increased.*   In most birds, I believe in all that fty,
these axillary cells communicate with the cavity of the os humeri,
by means of small openings in the hollow surface near  the head  of
that Bone; in  some they are continued  down the wing, communi-
cating with the ulna and  radius;  in others they reach even as far
as the pinions.  The ostrich,  however, is an exception.
  The posterior edge of the lungs (which lies on  the  sides  of the
spine, and projects  backwards between the ribs,) communicates
with the cells of the bodies of the vertebra), with those  of the  ribs,
the canal of the medulla spinalis,  and the cells of the  sacrum and
other bones of the pelvis ;  from which parts the air finds  a passage
into the cavity of the thigh-bone.   This takes place in  the greatest
number of birds; but in some the air is even continued part  of the
way down the thighs.  This  account  agrees with what  we  gene-
rally find, though some birds  have more, and some fewer of these
communications;  for, in the ostrich, no air gets into the os humeri,
yet it enters into every other  part, as before described, and in very
large quantities.  In the common fowl no  air appears to  enter any
bone except the os humeri.  The woodcock  has no air-cells, either
in the first bones of the wing  or in the  thigh-bones.  On  the other
hand, in the pelican the air passes on to the  ulna and radius, and
into those bones which answer to the  carpus  and metacarpus  of
quadrupeds.t
  Thus the cells of the abdomen, those surrounding the pericardium,
those situated at the lower and fore part  of  the  neck and in the
axilla, those in the cellular membrane  under the pectoral muscles,
as well as in that which unites the skin to  the body, all  communi-
cate with the lungs, and are capable of being filled with air; and
again, from them the  cells  of the  sternum, ribs, vertebras of the
back and loins, bones of the pelvis,  the humeri, the ulna and radius,
with the pinions and  thigh-bones, can  in  many birds  be furnished
with air.
   It is not by the lungs alone that air is conveyed into the bones of
birds, for the  cells of the diploe between the  two plates of the skull,
in some birds, receive a considerable quantity of air by the Eusta-

  * [While inflating the air-cells of a gigantic crane  (Ciconia Argala), in which
bird they are continued along the wing, beneath the skin, as in the pelican, the
wings became extended as the air-cells were filled.  This phenomenon suggested
to me a secondary use of the air-cells, which appears not to have been noticed,
viz., to render mechanical assistance to the muscles of the wings, both by keep-
ing the wing extended during the long hovering flight peculiar to this bird,  and
also by compressing and bracing the muscles, as is done  by the fasciae of the ex-
tremities in man.]
  f [In the hornbill the air is also extended into the phalanges of the toes, and in
short into every bone in the skeleton; whilst  in the penguin, on the other hand,
the air-cells are. confined, as in reptiles, to the thoracic abdominal cavity, and not
a single bone of the skeleton is permeated by the atmospheric fluid.  These birds
present the two extremes of the condition of the respiratory apparatus described
by Hunter in the present paper.] 
OF AIR-CELLS IN BIRDS.
199
chian tube.*   Of this the owl is a remarkable instance.  The lower
jaw of some kinds is  likewise supplied with  air, and often by the
same  canal.f  Some  authors have  considered the  diploe in the
cranium of a bird as a continuation of the mammillary process, and
looked upon it as a circumstance peculiar to singing birds, which is
not really true.
   These facts, which  had  been formerly observed, led >me  in the
year 1758 to make several  experiments upon the breathing of birds,
that might prove the free communication between the lungs and the
before-mentioned parts.
   First, I  made  an opening into  the belly of a cock, and having in-
troduced  a  silver canula,  tied up the trachea.  I found that the
animal breathed by this  opening, and might have lived;  but by an
inflammation in the bowels coming  on, adhesions were  produced,
and the communication  was cut oft".
   I next cut the wing through the os humeri, in another fowl, and
tying up the trachea, as  in the cock, found that the air  passed  to
and from  the lungs  by the  canal in  this bone.  The same experi-
ment was  made  with the os femoris of a young hawk, and was at-
tended with a similar  result.   But the passage of air through the
divided parts, in both these experiments, especially  in the last, was
attended with more difficulty than in  the former one ;  it was indeed
so great as to render it impossible for the  animal to  live longer than
evidently to prove that it breathed  through the cut bone.
   I have made several preparations of these cells, by throwing into
the trachea an injection, commonly called the corroding injection,

  * The only thing in other animals similar to this communication in birds, of the
cells of bonos with  the external air, is that which takes place in the internal ear
of quadrupeds, by means of the Eustachian tube.a
  X When I wrote this account  to  send it to the Royal Society, I did not then
know by what means this  was done; for in  that  I said, " but by what means I
do not know;" that is, I did not  know whether it was conveyed by the trachea,
where it passes along the neck, or the Eustachian tube. Professor Camper,
when he did me the  honour to call upon  me, was so obliging as to  take some
pains to show me, in the lower jaw of the hawk, the hole where the air entered,
which makes me suspect he  did  not understand what I had written.  For after
having given the marks by which such openings were particularly distinguished,
it will hardly be supposed  I  could say that I did  not know the hole where the
air entered.6
  a [Camper, besides citing the mastoid processes as an analogous structure in
the mammalia, also adduces the extensive sinuses containing air in the cranium of
the elephant.  The air-cavities of the diploe of the cranial bones in the porcupine
are also remarkable for their extent.}
  b [In this note we have undesigned evidence that Hunter had never read the
Memoir of Camper, or he would hardly have  omitted  to notice the error into
which the Dutch anatomist falls with reference to the source whence the bones
of the head derive their internal supply of air.   Camper  states that it is received
by the meatus auditorii, believing that birds had no Eustachian tubes:  "l'air
entredans le diploe du crane entier par les trous auditifs; carlesoiseaux n'ont point
de trompes d'Eustache comme les quadrupedes et les  amphibies."  (Mem. de
Mathem. et de Physique, torn. vii. 1776, p.. 334.)] 
200           HUNTER ON THE ANIMAL CECONOMY.

which first filled the air-cells of the lungs, then all the others, such
as the cells in the abdomen, anterior and superior part of the chest,
axilla, os humeri, cells of the back-bone and thigh;  and  the whole
being afterwards put  into spirit of sea-salt, and corroded, the cast
of injection came out entire.
   The  singularity of  these communications in birds put me  upon
considering what might be their final intention.   At first I supposed
it  might be intended  to assist the act of flying, that being the cir-
cumstance which appears the most peculiar to  birds;  and it might
be of service in that respect, I  thought, by increasing the volume
and strength with the same quantity of  matter, wthout  adding to
the weight of  the whole, which indeed would rather be diminished
by  the difference of specific  gravity between  the external and in-
ternal air.  This opinion was strengthened by  discovering that  the
feathers of birds contained also a considerable quantity of air, in
the  very part  which  requires the greatest strength,  and  by  the
analogy which is observed between this mechanism  in birds and
what is discoverable in most kinds of fishes ; for these last have air
contained within their bodies, which I believe is commonly supposed
to lessen their specific gravity, although this does not appear so  ne-
cessary in fishes, which move in a much heavier element than birds.*

  * When we consider that the elevating and suspending apparatus  is much
smaller in fishes  than in birds, we may reasonably conceive the air in them was
intended as a kind of equilibrium between the fish and water; and that progres-
sive motion was the only thing wanted in the  actions  of fishes.  Wrere we to
reason upon  general principles alone, we should suppose that those fishes who
have the largest air-bags should have their muscles of a greater specific gravity,
and those fishes that have none should have the lightest flesh ; therefore that the
flesh of the salmon and cod, which have an air-bag, should be heavier than that
of the shark, which has none.   But to know how far this, which appeared to be
reasonable, was a fact, I made the following experiments:
  Experiment I.  I took a  portion of muscle of the shark, cod, and salmon, of the
same weight in air;  and  first examined how far they occupied the  same space,
by immersing them in water, and observing the rise or fall of the water upon each
of them being separately immersed in it.
  The shark occupied the smallest space, the salmon a  little more, and the cod
the largest.
  Experiment II. I then suspended the same three portions, upon a level, in a
glass vessel filled with water about two feet high, and let them all go at the same
instant, to see which would fall through the water in the shortest space of time.
The shark got to the bottom first, the  salmon next, and the cod last.
  It is necessary to observe that, in both these experiments, the difference in bulk
and in the times of their falling was very little, but, however,  sufficient to ascertain
the fact for which the experiments were instituted.
  To see how far the muscular flesh of birds was specifically lighter than that of
a quadruped, I repeated the above experiments upon a portion of a hind,  of a
pigeon, and of a sheep; but could discover no visible difference in their weight.
  It may be observed there are in common two situations of oil in fishes: in one
it is diffused through the fish, as if the body had been  steeped  in it, as  in the
salmon, herring,  &c.  In  the other it is found  in the liver, as in all of the ray
kind, cod, &c, and in general those that have it in one part have none in the
other; however, there are some, although I believe but few, who have their oil
in form of what may be called fat, viz., in flakes in the interstice of parts, as the
sturgeon.  The  liver, in  those of the ray kind, is large, and extended through 
OF  AIR-CELLS IN BIRDS.
201
But when I found that the ostrich (which is not intended to fly) was
amply provided with  these cells; and that the  common fowl, and
many others of that class, which  are endowed  with the faculty of
flying, were less liberally supplied ;  when I saw that even the wood-
cock, which flies and is supposed to be a bird of passage, was inferior
in this respect to the ostrich, and that the bat differed not in structure
from animals that do not  fly ;*  I was  compelled, by so many con-
tradictions to theory, to suppose that this singular mechanism might
be intended  for some other purpose.
   The next  conjecture that offered was that these cells were to  be
considered as an appendage to the lungs; and to this I was led  by
the analogy  observable  between birds  and  amphibious animals.
For although both in  the bird  and amphibious tribe, as the snake,
viper, and many others, the lungs are continued down through the
whole belly, in form of two bags,f and therefore appear to be larger
than the lungs in any  other animal, yet in all of them the quantity
of surface exposed to the air is much less than in the quadruped ;
for the cells of the lungs in the bird are larger, and in the snake, &c.
the upper part only can perform the office of respiration with any
degree of effect, the  lower having  comparatively  but few air-ves-
sels.   The air must pass through this upper part  before it gets to
the lower in inspiration, and must also repass in expiration, so that
the respiratory surface has more air applied to it than what the lungs
of themselves could contain.  It is not however to be supposed that
the air can be made to pass to  and fro  in bones as in parts which
admit of contraction and dilatation; the purpose answered by these
bony cells must therefore be different, and perhaps  they should  be
considered as reservoirs of air.J   There is in  fact a  great similarity

the belly;  therefore it might  be supposed to lighten the body, from  oil being
lighter than water or the flesh,; but we have oil in the liver of the cod, and in the
salmon and herring the oil is  diffused through the whole: therefore I am afraid
we are not yet acquainted with the full effect of the air-bladder in fishes.
   * [This is not  absolutely true; for it is a remarkable fact,—and one which
gives additional probability to the hypothesis of Borelli as to the final intention,
of the air-cells of birds in diminishing the specific gravity for the facilitation of
flight,—that in one genus of bats (Nycteris of modern naturalists) remarkable for
their lofty and continued flight,  air-cells are continued beneath the integument,
which are inflated from the cheek-pouches.  " The skin adheres to the body,"
says Bell, in his  excellent article Cheiroptera (Cyclop,  of Anatomy, p. 599),
" only at certain points, where it is connected by means of a loose cellular mem-
brane : it is therefore susceptible of being raised from the surface, on the back
as well as  on  the under parts.  These large spaces are filled  with air at the will
of the animal, by means of large cheek-pouches, which are pierced at the bottom,
and thus  communicate with the subcutaneous spaces just mentioned.  When
the animal, therefore, wishes to inflate its skin, it inspires,  closes the nostrils,
and then, contracting the cavity of the chest, the air is  forced  through the open-
ings in the cheek-pouches under the skin, whence it is prevented from returning
by means of a true sphincter,  with which those openings are furnished, and by
large valves on the neck and back.  By this curious mechanism the bat has the
power of so completely blowing up the spaces under the skin as to give the idea
of a little balloon, furnished with wings, a head, and feet."]
  f [In moat  snakes the  abdominal  air-bag is  single, but  a rudiment of the
second lung exists.]
  X It is not to be supposed that the  air in the cells  in  birds will be changed 
202
HUNTER  ON THE  ANIMAL  CECONOMY.
between  birds  and  that class of  animals  called  amphibia;  and
although  a bird and  a snake are not the same in the construction
of the respiratory organs, yet the circumstance of the air passing m
both beyond  the  lungs, into  the cavity of the abdomen, naturally
leads us to suppose that a structure so similar is designed in each to
answer a similar  purpose.   This analogy is still further supported
by the lungs in both  consisting of large cells.*   Now in amphibious
animals the use of such a conformation of the lungs is  evident,  as
it  is  in consequence of this  structure  that they  require to breathe
less frequently than others ; and in this respect it  may in birds have
some connexion with flying, as that motion might  easily be imagined
to render frequency  of respiration inconvenient, and  a reservoir of
air would therefore become singularly useful.  Although we are not
to consider this structure in birds to  be an extension of lungs, yet
I can  easily conceive this accumulation of air to  be  of great use
in respiration.  For  it was observed before respecting the amphibia,
that the air in its passage to from these cells must certainly have a
considerable effect upon the blood in the lungs, by allowing a much
greater quantity of air to pass in a given time than, if there was no
such construction of  parts ;f  and this opinion will not appear to be
ill founded, if we  consider that  both in  the bird and in the viper
the surface  of the  lungs  is  small in  comparison to what it is in
many other animals  which have not this extension of cavity.   It is
also a corroborating circumstance, that in the fowl, the air might have
passed by a much readier way  than through the lungs into all the
cells about the breast, neck,  axilla,  wings,  &c, as these  could have
been  filled from the lower end of the trachea, upon which many of

while flying; only accumulated and retained; not  in the least influenced  by
either inspiration or expiration.  It might be asked, Where is the stricture upon
the air when flying, so as  to keep  the  parts distended ]   Is  it upon the outlets
from the lungs, or is it at the glottis, as in  the quadruped 1  For we may observe
that when an animal is using considerable exercise, it never  either expands the
lungs, nor makes a full expiration, giving  the ribs and diaphragm as little extent
of motion  as possible, so that the body may be kept firm, which  obliges  it to
breathe oftener; and as this quantity of air is  not sufficient for the accelerated
motion of the blood, the  animal gets what is called out of breath, which is no
more than the two not being proportioned ; and when it rests, it breathes as quick
and takes as long strokes as possible, to make up the loss.  So that in exercise
we probably breathe less air.
  * [The air-cells are smaller, and much more numerous in the lungs of birds
than in the corresponding anterior or true respiratory portion of the lungs of rep-
tiles.  The analogy which Hunter here mentions, as also that between the ab-
dominal air-receptacles of birds and the air-bladders of fishes, to which he previ-
ously alludes, had not escaped the observation of Hervey, who says, " Quin etiam
(quod tamen a nemine hactenus observatum memini) avium bronchia, sive asperse
arteriae fines, in abdomen perforantur, aeremque inspiratum intra cavitates illarum
membranarum reconduct.  Quemadmodum pisces,  et  serpentes  intra  amplas
vesicas in abdomine positas eundem attrahunt et reservant; eoque facilius natare
existimantur."—De Generatione Animalium, Ex. 111.]
  f It may, perhaps, occur to some, that the whole of these communicating cells
are to be considered as extended lungs; but I can hardly think that any air which
gets beyond the vesiculated lungs themselves is capable of affecting the blood of
the animal, as the other  cavities into which it enters, whether of the soft parts or
of the bones, appear to be very little vascular. 
OF AIR-CELLS IN BIRDS.
203
them lie.   But the air must now take a roundabout passage both in
its way in and its way out, those openings being upon  the exterior
surface of the lungs.  We must not, however, give up the  idea  of
such structure being of use in  flying ;  for I  believe we  may set it
down as a general rule, that in  the birds of longest and highest flight,
as eagles, this diffusion of air is extended further than in the others.
This opinion  is  strengthened  by comparing  the structure above
described with the respiratory organs in the flying insects, which
are composed of cells diffused  through the whole body;  these are
extended even into the head and down the extremities; while  there
is no such appearance  in the insects that do not fly, as the spider;
but why the pelican  should be so  amply provided I cannot say, not
knowing the natural history of that  bird sufficiently to be able  to
judge of this  point.   Do they carry weights in the large fauces so
great as to require such an increase  of substance without  increase
of weight ?
   How far this  construction of  the  respiratory organs may  assist
birds in singing  deserves investigation, as the vast  continuance of
song, between the  breathings, in a  canary-bird would appear to
arise from it.  This is  a  subject, however, which  I  shall not at
present enter upon.*

   * [The objection offered  by Hunter in the preceding note to the use of the air-
cells as  accessory organs  of  respiration, is weakened, if not removed, by the
anatomical  fact that the bronchiae open into  them by such direct and  wide
apertures as to render it  most probable that much of the air passes at once into
the air-receptacles without having previously been'decomposed in the vesicles of the
lungs.   It may be concluded, therefore, that the respiratory function is heightened,
in harmony with the increased energies of the circulating and locomotive powers
in birds, by means of the extensive system of continuous air-receptacles  above
described, which operate both by effecting a change in the blood of the pulmonary
circulation in the return  of the air of the cells through the bronchial tubes, and
also by the change which the blood undergoes in  the capillaries of the systemic
circulation, which are in contact with the air-receptacles.
   A second use of the  air-receptacles  in reference  to  the respiratory function
arises out of the mechanical  aid which they afford  in  the action of breathing.
During  inspiration  the  sternum of  the bird is depressed or recedes from the
spine, the angle  between the vertebral and sternal ribs is made less acute, and
the thoracic cavity proportionally enlarged ; the air then rushes into the  lungs
and into the thoracic air-receptacles,  while those of the abdomen become flaccid;
when the sternum is raised, or approximated towards the spine, part of the air is
expelled from the lungs  and  thoracic cells by the trachea, and part driven into
the thoracic receptacles, which are  thus alternately enlarged  and diminished
with those of the thorax.   Hence  the lungs, notwithstanding their  fixed con-
dition, are subject to due compression through the medium of the contiguous air-
receptacles, and are affected equally and regularly by every motion of the ster-
num and ribs.
  A third use, and one which Hunter inclines to admit, is that of rendering the
whole body specifically lighter, in relation  to the peculiar actions of flight. ,A
diminution of specific gravity must  necessarily follow  the desiccation of the
marrow  and other fluids  in those spaces which  are occupied with the air-cells,
and by the rarefaction of the contained air by the heat of the body.  In harmony
with this view are the facts, not only that  the quantity of air admitted into the
system is in proportion to the general  powers of flight, but also that in birds where
the skeleton is only partially permeated by air, this is especially distributed to 
204
HUNTER ON THE ANIMAL  CECONOMY.
18. A DESCRIPTION OF THE NERVES WHICH SUPPLY
                 THE ORGAN  OF SMELLING.

   The nerves being in themselves perhaps the most difficult parts
of an animal body to dissect, becomes a reason why we are still
unacquainted with many  of their minuter ramifications; yet if a
knowledge of these, together with that of their  origin, union, and
reunion, is at all connected with  their physiology, the more accu-
rately they are  investigated the  more  perfectly will the functions
of the nerves be understood.
   I have no doubt, if their physiology was sufficiently known, that
we should find the distribution and complication of nerves so imme-
diately connected with their particular uses, as  readily to explain
many of  those peculiarities for  which it  is  now  so  difficult  to
account.  What naturally leads  to this opinion  is, the origins and
number of nerves being constantly the same, and particular nerves
being invariably destined for particular parts, of which the fourth
and sixth pair of nerves are remarkable instances.  We may there-
fore reasonably conclude, that to every part is allotted its particu-
lar branch, and that however complicated the distribution may be,
the complication is always regular.
   There are some nerves which  have a peculiarity in their course,
as the recurrent and  chorda tympani; and others which are appro-
priated  to particular sensations, as those which go to four of the
organs of sense, seeing, hearing,  smelling, and tasting; and some
parts of the body having peculiar sensations (as  the stomach and
penis), we may, without impropriety, include  the fifth, or sense of
feeling.   This general uniformity in course, connexion, and distri-
bution, will lead us to suppose  that there may be some other pur-
pose  to  be  answered than  mere  mechanical convenience; and
many of the  variations which have been described  in the dissec-
tions of nerves, 1 believe to  have  arisen from the blunders of the
anatomist, rather than from any  irregularity in their number, mode
of ramifying, course, distribution, or connexion* with each  other.
those members which are most employed in locomotion: thus it is admitted into
the wing-bones of the owl,but not into the femur; while in the ostrich the air
penetrates to the femur, but not the humerus or other bones of the wing.
   I have already alluded to the secondary use which the air-cells  may afford to
some large  and long-winged bird, which, like the Argala, or the  Frigate Bird,
hover with a sailing motion for a long-continued period in the upper regions of the
air, by diminishing the necessity for muscular exertion by the' tendency of the
distended air-cells to maintain the wings outstretched.  Of the same adventitious
character is the use finally suggested by Hunter to the air-receptacles, of contri-
buting to sustain the song of birds,, and to impart to it tone and strength.  It is
no just objection to this function that  the air-cells exist  in birds which are not
endowed with  the mechanism and power of song, since it is not pretended that
this is the primary or exclusive  office of the air-cells.  The latest writer on the
pneumaticity of birds, M. Jacquemin, has indeed reproduced this suggestion of
Hunter's as a novel idea.]
   * Here it is to be understood I do not mean lateral connexion, such as two
branches uniting into one chord and then dividing; or a branch going to a part, 
            THE NERVES OF THE ORGAN OF SMELLING.       205

   We observe  no  such uniformity in vessels carrying  fluids, but
 find particular purposes answered by varying their origin and dis-
 tribution :  the pulmonary  artery answers a very  different  purpose
 in the circulation of the blood from that of the aorta ; yet both arise
 from  the same source, the heart.   The course of the arteries is such
 as will convey the  blood  most conveniently, and therefore not
 necessarily uniform, it  not  being very material by what channel,
 provided  the  blood is  conveyed to the part;  though in particular
 instances  certain  purposes  may be answered by a peculiarity in
 origin and distribution, as  happens in the testicle of quadrupeds.
 This observation respecting arteries is  likewise applicable to veins,
 and still more to the  absorbent vessels; in  which last,  regularity
 is even less essential than in the veins.                           •
   Whoever, therefore, discovers  a  new artery, vein, or lymphatic,
 adds  little to  the  stock of  physiological  knowledge; but he who
 discovers a new nerve, or furnishes a more accurate description of
 the distribution of  those already  known, affords us information in
 those  points which are most likely to lead to an accurate knowledge
 of the nervous  system;  for if we  consider  how various are the
 origins  of the  nerves, although all arise  from the brain, and how
 different the  circumstances  attending  them,  we  must suppose a
 variety of uses to arise out of every peculiarity of structure.*
   Indeed, if we reflect on the actions arising immediately from the
 will and  affections  of the  mind, we must see that the origin, con-
 nexion, and distribution of the  nerves  ought  to be exact, as there

 either single or double, for still it is the  same nerve; or'whether a branch unites
 with another a little sooner or a little later, for still it is the same branch.  Such
 effects  may arise more from a variety in the shape of the bodies they belong to,
 than any variety in the nerves themselves.a
  * [With reference to anatomical researches on the nervous system, Sir Charles
 Bell has observed: " Whilst the nerves are supposed to proceed from one great
 centre,  to have  the same structure and  functions, and to be all sensible, and all
 of them to carry what  has been vaguely called  nervous power, these discoveries
 of new nerves and ganglia are worse than useless; they increase the difficulty,
 and repel inquiry."—Exposition of the Natural System of the Nerves of the Human
 Body, 1824, p. 70.
  The different views entertained by Hunter on this subject doubtless arose from
 his belief that a variety of uses arose out of the various origins and other pecu-
liarities of structure of the nerves.  Hence he was led to trace the different nerves
which are distributed to a single organ to their different origins, and to infer that
the organ thereby received different sensitive endowments.  It is this principle,
in a more extended application from the nerves to their component filaments, so
far as they have different origins, which  forms the basis of the present improved
doctrine of the nervous system.  " The key to the natural system of the nerves,"
says Bell, " will be found in the simple proposition, that each filament or track
of nervous matter has its peculiar endowment, independently of the others which
are bound up along with it, and that it continues to have the same endowment
throughout its whole length."—Ibid.]
  a [See the observations of Swan on the exceptions which occur in the uniformity
of the anatomical conditions of the nervous system, in his excellent 'Demonstra-
tion of the Nerves of the Human Body,' pp. 29, 30, 31.]
                                 19 
206
HUNTER ON THE ANIMAL  CECONOMY.
are parts whose actions immediately depend upon  such circum-
stances.   The  brain may be considered as having an intelligence
with the body ;  but no such intercourse subsists between the differ-
ent parts of the body and the heart.
  In the summer of  1754, being much employed  in  dissecting the
nerves passing out of the skull, I was, of course, led to trace many
of their connexions with those from the medulla spinalis ;  and was
assisted  by Dr. Smith, then pursuing his  studies in London.*   The
better  to "trace these nerves through  the  foramina of the skul, I
steeped the head in a weakened  acid of sea-salt till the bones were
rendered soft, and that  the parts might be as firm as possible, and
at the same time free from any tendency to putrefaction (it being
summer), the  acid was  not  diluted with water, but with spirit.
When  the bones wrere rendered  soft, pursuing my intention, I dis-
sected  the first pair of nerves, and discovered their distribution ; and
having made a preparation of the parts in which  they were found,
I immediately had drawings made from them, with a view to have
presented the account to the Royal Society ;  but other pursuits pre-
vented it.f Engravings were afterwards made from these drawings,
and  the  preparation was  repeatedly shown  by Dr. Hunter, in his
courses of anatomy, who,  at the same  time, pointed out that altera-
tion  in the mode  of reasoning upon those  nerves  which would
naturally arise  from this  discovery.   In this  dissection I found
several nerves, principally from the fifth pair, going to and lost upon
the membrane  of the nose ; but  suppose that those have nothing to
do with the sense of smelling, it being more than probable that what
may be called organs of sense have particular nerves, whose mode
of action is different from that of nerves producing common sensa-
tion, and also different from one another, and  that  the nerves on
which  the peculiar functions of each of the organs of sense depend,
are  not  supplied from different parts of the brain.   The organfof
sight has its peculiar nerve ;  so has that of hearing;  and  probably
that of smelling likewise;  and, on the same principle, we may sup-

  * Dr.  Smith was afterwards teacher in chemistry and anatomy in the university
of Oxford ; is now Savilian professor of geometry, and lecturer in physiology.
This account of the first pair of nerves, as also of the branches of the fifth, is taken
from the original description written by him, and taken from my dissection when
I was tracing them.
  X Dr. Scarpa, professor of anatomy at Pavia, while in London in  1782, ac-
quainted me that he had dissected the ramifications of the olfactory nerves, and
that on his return  to Italy he meant to publish an account of them.  At this time
I showed him my drawings and engravings.  I have lately been informed that
he has published his account, but have not met with it: I  have, however, seen
one of his engravings, which was  executed in London, and is very elegant.   It
only shows those on the septum narium, whose minuteness  is rather carried
further than the power of dissection, and the ramifications are more regular than
we find them in Nature.a
  a [See Scarpa, Anatomicx Disquisitiones de Auditu et Olfactu, fol. 1789, and
Anatomicarum Annotationum, Liber secundus De  Organo olfactus praecipuo, deque
Nervis nasalibus interioribus e Pariquinto Nervorum cerebri, 4to., 1782.] 
THE NERVES OF THE ORGAN OF SMELLING.       207
pose the organ of taste to have a peculiar nerve.  Although these
organs of sense  may likewise have nerves from different parts of
the brain, yet  it  is  most probable such nerves are only for  the
common sensations of  the part, and other  purposes  answered by
nerves.   Thus we find  nerves from different origins going to  the
parts composing the organ of sight, which are not at all concerned
in the immediate act of vision;  it is also probable, although not so
demonstrable, that the parts composing the ear  have nerves  be-
longing  to them simply as a part of the body, and not as  the organ
of a particular sense: and if we carry this analogy to the nose, we
shall   find a nerve, which we may call  the peculiar nerve of that
sense : and the other nerves of this  part, derived from other origins,
only conveying common  sensation, and  we  may suppose only in-
tended for the  common  actions of the part.  This mode of reasoning
is equally applicable to the organ of taste; and  if the  opinion of
peculiar nerves going to particular organs of sense be well founded,
then the  reason  is  evident  why the  nose, as a part of  our body,
should have nerves  in common with other parts, besides its peculiar
nerves ;   and, as the membrane of the nose is of considerable extent,
and has a great deal of  common  sensation, we may suppose the
nerves sent to this part for that  purpose will not be few in number.
It is upon this principle the  fifth pair of nerves  may be supposed to
supply the eye and nose in common with other parts ;* and upon
the same principle, it is more than probable, that every nerve so
affected as to  communicate sensation, in whatever part of the nerve
the impression  is  made, always gives  the  same sensation as  if
affected  at the common  seat  of the sensation of that  particular
nerve.f

  * [Since the period when Hunter wrote this  remarkable paper, in which the
principle  of different nerves having particular functions in relation to differences
of origin and other anatomical conditions is so distinctly enuntiated, the attention
of physiologists  has been more especially called to the fact of the organs of sense
being supplied by nerves from different sources, for the purpose of different en-
dowments, by the experiments of Magendie.  He divided the fifth pair of nerves
within the cranium, and thus contributed to define more exactly than had before
been done the importance of common sensation to'the safety of some of the organs
of sense, as the eye, and also the share  which touch bears  in the  impressions
 received  by the  organs of special sense, as in that of smell.
   Physiological science does not perhaps afford a more  striking example of the
inferiority of mere  experimental inquiry  to that which  is based on extensive
anatomical induction, than the singular conclusions at which Magendie arrived
after performing the experiment above alluded to. There are few physiologists,
however, who do not adopt the conclusions of Hunter, that the organs of sense
receive their endowments of ordinary sensation from the  fifth pair, which  is
common  to each, in preference  to the well-known  view originally adopted by
 Magendie.  (See Journal de Pysiologie Exper., vol. iv., 169.  " Le nerf olfactif
est-il l'organe de l'odorat ?")]
   ■j- I knew a gentleman who had the  nerves which go to the glans penis com-
 pletely destroyed by mortification, almost as high as the union of the penis with'
 the pubes; and  at the edge of the old skin, at the root of the penis, where the
 nerves terminated, was the peculiar sensation of the glans penis ;  and the sensa-
 tion of the glans itself was now only common sensation ; therefore the glans has 
208          HUNTER ON THE ANIMAL CECONOMY.
   The first pair of nerves arriving at the part of its destination as
 soon as it escapes  from the skull, and immediately ramifying, has
 rendered its distribution more obscure  than  that  of  the  others,
 whose course to the part to which they are allotted is visible and to
 be traced.  As the body of the nerve, while within the skull, is pulpy
 and composed of the brain itself, it easily breaks off at the very di-
 vision and exit of the small branches; it  therefore becomes  impos-
 sible to trace them, as we usually do other nerves; and they have
 by most physiologisls been considered as  never forming chords, but
 going on in their pulpy form to be distributed  on the membrane of
 the nose, in a mode somewhat similar to that  of the optic  nerve,
 and to what is commonly supposed  to take place with respect to
 the portio mollis  of the seventh pair.  Winslow  has suggested an
 idea  that the first pair forms chords; but it is only as an assertion,
 and not having described them, that alone was not sufficient to alter
 the former mode of reasoning.
   Haller, who is to be considered as the  latest anatomist and phy-
 siologist, who has published on the subject, on whom we  can depend
 says, that" The first pair  of nerves  makes its  way  into the nose
 covered by the pia mater only, very little altered from  what it was
 when within the cavity of the skull."*  This shows that Haller re-
 tained the old idea concerning  these nerves; but we  shall find that
 they become firm chords immediately upon piercing the dura mater
 and cribriform plate of the ethmoid bone.
   The first pair, while  within the skull, differs in  some respects
 from all other nerves :  firstly, it seems to be made up of a cortical
 and medullary substance ; while the others appear to consist of me-
 dullary alone; and  secondly, it is  different, in that it does not seem
 to be composed of fasciculi, and has  but one covering from the pia
 mater investing the  whole nerve,  whereas  other nerves appear to
have  a covering  round  each  fasciculus;  and this is probably  the
 reason why the first pair is  weaker while within the  skull than  the
others.   Its form is somewhat triangular,  having three edges, from
lying in a  groove made by two convolutions  of the  brain.  The
 course is forwards,  a little  upwards and inwards, and where it lies
upon the cribriform plate of the ethmoid  bone  becomes somewhat
larger, and divides into a great many branches, like so many roots,
answering to the number of holes in that plate, except one left for a
branch  of the  fifth  pair; but these divisions we cannot see, they
being covered by the body  of  the nerve,  which cannot  be  raised
without breaking off the small branches at their origin. As  the

probably, different nerves, and those for common sensation may come through the
body of the penis to the glans.
  A Serjeant of marines, who had lost the glans and the greater part of the body
of the penis, upon being asked if he ever felt those sensations which are peculiar
to the glans, declared, that upon rubbing the end of  the stump, it gave him exactly
the sensation which friction upon the glans produced, and was followed by an
emission of the semen.
  * Elementa Physiologiae, vol. v., p. 151. 
     OF SOME BRANCHES OF THE FIFTH PAIR OF NERVES.  209

branches of the nerve pass through this bone,  they seem to take
processes from the dura mater along with them,-then becoming firm
chords, similar to other nerves.  These branches, after they have
got through the bone, form themselves into two planes or divisions,
one  passing  on  the  septum,  the  other on  the turbinated bones.
Those of the  septum narium, in  their passage to the nose, are first
continued a little way down, in bony canals of the perpendicular
lamella of the ethmoid  bone, which holes become small grooves in
that bone*"; and those on the opposite side being more numerous and
smaller, pass  down through small holes that are on the inside plate
of the ethmoid bone, which holes are likewise continued into grooves,
for a little way, upon that plate. . When the branches get upon the
membrane of the nose, they subdivide  into  a great many smaller
ones, which are somewhat flattened, and are only to be seen on that
side of the  membrane that adheres to  the bones, not being visible
at all on the other; so that the dissection of these nerves is no more
than separating the membrane and bone from  each other.  They
can hardly be dissected all round;  and the further they  are traced
upon the membrane the fainter they become, and growing smaller
they sink deeper and  deeper into  the membrane to get on its
outer surface, where we must suppose they terminate.  Those upon
the septum pass down a little radiated, and the branches, especially
at the upper part, or at their first setting  out, unite with one another.
Those on the side  next the antrum, when they have reached the
membrane  of the nose, in their course  to the superior  turbinated
bone, form a  very considerable network or plexus; and when they
reach that bone,  do not all go round its  convex curvated pendulous
edge to  the concave side, but some passing through its substance
get immediately upon it, which is the reason why we find so many
holes in that  bone.  It is difficult to trace them further; but we
have reason to suppose that they go through  the inferior turbinated
bone in the same manner, since  we find similar holes.
19.  A DESCRIPTION OF  SOME  BRANCHES  OF THE
                FIFTH PAIR  OF NERVES.

  Lv tracing the course of the olfactory nerves, I  also  discovered
several branches of the fifth pair not commonly known, particularly
two that were supposed to go to the  membrane of the nose for the
sense  of smelling, but which only pass through that organ to their
place of destination.  The first is a small nerve from the first branch
of the fifth pair; or, according to Winslow, the nervus ophthalmi-
cus Willisii,  which small  nerve  is called  by Winslow the nasal.
This branch, after having passed  out of the skull into the orbit, re-
enters the  cranium through the foramen orbitariumanterius, and gets
                             19* 
210          HUNTER ON THE ANIMAL CECONOMY.
on the cribriform plate of the ethmoid bone; from thence it passes
down through one of the anterior holes of the cribriform plate, and after
having continuect its course in a groove on the nasal process of the
frontal bone, runs forward and downward in a similar groove on
the inside of the os nasi;  from thence getting on the outside of the
cavity of the nose, it runs along the cartilaginous  part of the ala,
and near the extremity of the nose mounts up upon the  tip of the
ala, and  then dipping down between the two alse,  is lost on the
anterior  extremity of the  cartilaginous  septum.   In  its ^course it
sends several small filaments into the alae.
   The second  is a  branch of the superior maxillary nerve; for
that nerve, having passed through  the foramen rotundum, divides
and sends off several branches, one of which  passing  backwards
and inwards, through the foramen commune,  between the orbitar
process of the palate, and the root of the ala of the sphenoid bone,
gives a branch which gets into a fissure  that seems to separate the
root of the ala  from  the body of the sphenoid bone, where that bone
makes the roof of the nose.  This branch then passes  along the
under surface of the body of the  sphenoid  bone, in its way to the
septum narium, and getting upon that part, passes along between its
membranes and the bone : its  course is  downwards,  and forwards
towards  the foramen incisivum, through which it passes and is lost
in the gum behind- the first dentes incisores, and on the membrane
of the roof  of the mouth at  that part.
   There is another branch of the superior maxillary nerve, which
comes off from a large  branch that is going  down to the mouth,
uvula, &c,  and this  branch, with its division  into two, has  been
described by Professor Meckel, of Berlin; but after tracing one of
these into the portio  dura, he pursued the search no further.  This
branch of the  superior maxillary nerve passes back through the
foramen pterygoideum, accompanies the carotid artery as it passes
across the posterior edge of the foramen, and there divides into two
branches; one of which passes down along with the carotid artery,
through  the basis of the  skull, and proceeding in  a direction con-
trary to the course of the artery, in contact with that  branch of the
cervical ganglion that passes up with the carotid artery to join the
 sixth pair, then joins the first cervical ganglion.  The other branch
decussates that artery on its upper surface, and  getting upon the
anterior side of the petrous portion of the temporal bone, enters a
 small hole near the bottom of that large one which affords a pas-
 sage to the  seventh pair cf nerves, joining the portio dura just where
 that  nerve,  making its first turn, passes  along with it through what
 is called the aqueduct.  This nerve,  composed of portio dura, and
 the branch  of the  fifth  pair, sends off, in the adult, the chorda
 tympani before its exit from the skull; and in the foetus immediately
 after.  The termination  of the branch, called chorda tympani, I
 shall not describe; yet I am almost certain it is not a branch of the
 seventh pair of nerves, but the last-descibed branch from the fifth
 pair; for I think I have been able to separate this branch from the 
CROONIAN LECTURES ON MUSCULAR MOTION.      211
portio dura, and have found it lead to the chorda tympani; perhaps
it is continued into it; but this is a point very difficult to determine,
as the portio dura is a compact nerve, and  not so fasciculated as
some others  are.   However  this  may be, it is very reasonable to
suppose that the chorda tympani is a branch of the  fifth pair, as it
goes to join another branch arising from the same trunk.*
20.  CROONIAN LECTURE ON MUSCULAR MOTION, NO. I.

                        FOR THE YEAR 1776.

       [Read before the Royal Society, by Mr. John Hunter, F.R.S.f]

   A self-moving power is such a phenomenon  as must call up the
attention of the  thinking  mind (while ignorant of the cause); and
when  that very mind is connected with  this power it becomes still
more  interested.
   This power of motion was first discovered to  be inherent  in parts
of an  animal body of a certain construction, called muscles.J   This
construction appeared to  be a  composition of fibres, which were
called muscular: and motion was supposed to be produced by these
contracting  in length, and  all the varieties of motion in an animal

  * [This is a point which it is undoubtedly very difficult to decide by dissection
of the  parts in the human body. Cloquet, Hirzel, and  Majendie describe the
chorda  tympani according to the supposition of Hunter.  In the horse  and calf,
however,  where the portio dura is less dense in its structure,  the Vidian branch
of the fifth may be distinctly seen crossing that nerve after penetrating its sheath,
and separating into many filaments, with which filaments of the seventh nerve
are blended, and a ganglion formed by  the superaddition of gray matter; the
chorda  tympani is here continued partly from  this ganglion, partly from the
seventh or portio dura.]
  f [In Home's Account of the Life  of John Hunter, prefixed to the treatise
♦On  the Blood, Inflammation, and Gunshot Wounds,'1794,  p. xxviii., is the
following passage:
  " Besides the papers which  he presented to that  learned  body  (the Royal
Society),  he (Mr. Hunter) read six  Croonian Lectures upon the subject of  mus-
cular action, for the years 1776, 1777, 1779, 1780, 1781, 1782.  In  these  Lec-
tures he collected all his observations upon Muscles respecting their powers and
effects, and the stimuli by which they  are affected ; and to these he added  com-
parative observations upon the  moving powers of Plants. These Lectures  were
not published in the Philosophical Transactions; for they were withdrawn as
soon as read, not being considered by the author as complete  dissertations, but
rather as materials for some future publication."]
  X  [Both Aristotle and Hippocrates were  ignorant of the function of the muscu-
lar fibre :  the important discovery that the animal motions were performed by the
muscles is attributed to Lycus of Macedon, who wrote a voluminous work on
Myology.  It  is certain that the use of the muscles was  known to Herophilus,
since he is quoted by Galen as  having spoken of the happy disposition of the
muscles for the movement of the limbs.  To Herophilus belongs the honour of
having  first discovered in the nerves the organs of sensation and of voluntary
motion.] 
212
HUNTER ON THE  ANIMAL CECONOMY.
the most complicated, to be the result of the manner in which these
fibres were disposed.
   It is no wonde'r, then, that the mode in which a muscular fibre
produces  motion has been esteemed an inquiry not  unworthy the
attention of the greatest philosophers,  and has  almost universally
been one of the principal researches of the physiologist; especially
when we  consider that the substance, called  muscular, alone con-
stitutes the largest  part  of  most animals ; and indeed many are
wholly composed of it.
   The inquiries into the nature of self-motion  have been principally
confined to animals ; most probably from  the power in them being
more conspicuous, which almost prevented its being taken notice of
in any other substance whatever.  Inquiries into nature have, how-
ever, become less confined, and experiments and observations have
induced men to leave the beaten track of others, and take their ob-
servations from nature herself; by  which means  a self-moving
power  has been observed  and  universally allowed  in vegetables.
And this principle, upon investigation, appears now to be as much
a  property in vegetables as  in animals;  and in such  cases where
the functions and uses are the same in both, it  is  perhaps as con-
siderable in vegetables as animals.  But where they are dissimilar
in their actions, and the uses arising out of these  actions are also
different, it is reasonable to suppose the quantity of action will vary;
and such  difference must frequently occur in  both  animals and
vegetables. In animals a considerable part of this motion is called
muscular; in vegetables it has not yet got a name.
   The immediate cause of motion in all vegetables is  most probably
the same, and it is probably the same in all  animals; but how far
they are the same  in both classes  has not yet been determined.
But I think it will appear, in the investigation of this subject, that
vegetables and  animals have actions evidently common to both, and
that the causes of these actions are apparently  the  same in both :
and most  probably there is not  an  action in the  vegetable which
does not correspond or belong to the animal, although the mode of
action  in the parts may not be the same, or muscular, in both.
   There  appear, however, to  be  actions in animals  which  are
peculiar to them ; these make them more complicated, and in them
another  stimulus  to  action  is superadded, evidently for  that
purpose.*

  * [The actions  here  alluded to are the voluntary, which  are consequent
upon an act of sensation, and are the result of a determination or stimulus derived
from the brain.  The action in the  muscle produced by this stimulus is, how-
ever, essentially the same as is produced by mechanical or chemical stimuli ap-
plied to the muscle out of the body, or as takes place in the muscle involuntarily
as in sleep,  or when an animal is stimulated while in a state of hybernation, or
immediately after decapitation.
  Instead therefore of saying that animals have actions of the moving powers
peculiar to themselves, it is more correct to express, with reference to the volun-
tary actions, that they have parts superadded, for the  purpose of exciting the
actions of the moving powers, which the vegetable has not, viz., the  nerves.
It is true that the actions of the moving powers of an animal, whether automatic 
         CROONIAN LECTURES ON MUSCULAR MOTION.      213

   All  actions may  be  considered  of two  kinds, immediate  and
secondary.
   The first is an action  of the part itself, having no relation to any-
thing else ;. as action in  a muscle, or elasticity in a spring.
   The  second may be  divided into two  kinds,—first, where  this
action- has an effect  upon some other part, or moves it, which is the
ultimate effect, as the  heart moving the  blood by contracting,—
secondly, where the  action is applied  to some other  body adapted
for a particular  motion, which  is to produce the ultimate  effect,
such as the muscles  of a joint.
   We  may i/i general observe, from what we know of motion or
action  in matter, that it is always preceded  by something  which
we call the cause ; and that the immediate cause is an irresistible
impulse to action, which action becomes the effect.  A body endowed
with the power of self-motion  is under the same influence of  im-
pulse as matter in general:  it cannot move without an intermediate
cause for its motion.
   Self-motion may be of three kinds in the more perfect animals.
The first is where the motion is excited by a cause from within the
animal itself, and is employed in the (Economical operations  and
functions of  the  machine,  and  with  the materials the machine  is
already in possession of, which  are only made use of in the growth
of parts, secretion of fluids, &c.  The  second is where motion  is
excited from an  internal  cause, and  is employed in  particular
functions and operations, but where such materials used are out of
the body; as in those excited in consequence of hunger and thirst,
the passion between  the sexes, &c.   The third is where  motion is
excited by external  stimuli, and where whole parts are put in  mo-
tion : as where the sight or voice of a person excites one to approach
him; the application of a  medicine which excites  vomiting,  &c.
We can have no other  idea of these motions in animals but  that
they are muscular;  and as the two first  of these actions exist in
vegetables, it is natural  to  suppose that there is a similarity  in the
cause which  produces the  same final  intention, although the same
mode  of action  or  a similar power is not made use  of to pro-
duce it.
   These immediate causes  of action in an animal are  called stimuli,
and the capability in parts for  action  is  termed irritability;  but
such a definition is too  confined for the numerous actions excited
in an animal  body.
   The word  stimulus is pretty well determined in its signification;
it is an incitement to an action  of a proper or salutary nature :  but
the calling a part capable of  being  stimulated  ah  irritable part,
weakens the idea of the stimulus being the Cause of the action ;  and
indeed  the expression of a  part being irritated conveys  a  different
meaning from what  would  be annexed to the effect produced by a

or voluntary, are different from those which produce the motions of parts in
vegetables, as explained  in the notes, pp. 216, 222 ;  but the observations in the
text refer only to the voluntary actions.] 
214          HUNTER ON THE ANIMAL CECONOMY.
stimulus.  I would therefore define a « stimulus' to be the cause of
an increased natural action ;  and an  ' irritation' to be the cause of
an unnatural, disagreeable, or diseased action.
  Vegetables as well as animals have their motions produced  by
these causes, and are subject  to the very same laws.  A stimulus
or excitement to actions of a  salutary or proper kind is  simple, and
depends on the  original mode  of action, or the original laws of the
vital ceconomy, and  the action only changes in some degree as the
properties of the matter which stimulates  changes.   An  irritation
or excitement to morbid action is according to the susceptibility of
the body or part which is  to  be excited to action,  and alters ac-
cording to the  power  of the  irritating  matter, combined with the
various susceptibilities of different animals and parts for irritation;
for different animals and parts have different modes and powers of
receiving the same power of irritation.
  In the more perfect  animals we have the senses, or parts so con-
structed as  to  be  impressed  by the various properties of matter,
and, as it were, adapted to these properties alone.   These are con-
nected together by the brain, or common sensorium, which is com-
mon to the whole of the sensitive powers: to and from the brain
pass the nerves, or conductors of sensation and voluntary stimulus.
But as animals become  more and more imperfect, the senses, or
parts constructed so as to be impressed by the properties of matter,
become fewer, and  the  common sensorium  less  perfect.  There
appear to be animals entirely deprived of these parts or senses, and
consequently having neither brain nor nerves.*
  These senses give  us  intelligence of the various properties of
matter, from whence  we derive  our acquired actions, and  have
been naturally  led to suppose that there were no other causes of
action  in an animal body.
  The eye gives us at once the shape or limits, and  the various
effects  of the reflection of light from bodies at a distance; the first
of which could  not be sufficiently effected by the sense of touch, and
the second we  could not have had the least idea of, the common
powers of touch not being sufficiently acute.
  The ear is adapted to receive the vibrations of air, giving us
intelligence  of bodies at a distance.
  The nose is adapted for smelling, giving us the odorous proper-
ties of the matter of which bodies at a distance are composed.
  The tongue is adapted to tasting, giving us a property in matter
different from any discovered by the sense of touch.
  The  sense  of touch  gives us  a vast variety of information
respecting the form, construction, density, &c, of bodies.  In giving

  * [Mr. Hunter  nevertheless appears subsequently to  have believed that the
animals here alluded to, the Acrila of modern naturalists, had something similar
to the materials of the brain diffused through  the body; and that every other
principle or elementary tissue, as the  muscular fibre,  was diffused through the
whole, making every part alike contractile and stimulable, as in the fresh-water
polype,  Hydra viridis7\ 
         CROONIAN LECTURES ON MUSCULAR MOTION.      215

us form and construction it is somewhat similar to the eye; but it
is obliged to run over the whole for this intelligence, whereas the
eye takes in a larger scope of this intelligence at once.  However,
even the eye is obliged to do the same thing where the object is too
large, or where it is examining minutely.
  None of these senses are affected  by a stimulus or an  irritant,
although either the  one  or the  other may be carried so far as to
produce sensation.   This, however, is not a necessary effect, unless
the stimulus or irritant is the immediate object of sensation; as the
stimulus of light to  the eye, or the irritation of  too  much light  to
the eye.
  These organs of  sense are parts constructed  for sensation, and
those animals  that are endowed with all of them must be the most
sensible;  and  those that  are entirely deprived  of them  must be
wholly  insensible to every  impression  arising from  the  different
modifications or external influence of matter.
  The animals which receive no intelligence from external objects
have their actions arising out of immediate stimuli and irritants,*
and their consequent sympathies, which last extend to  the action
beyond the part of impression.  The perfect animals In some in-
stances seem also to be under  some  general power  or  external
influence, not  referrible to  any one sense  or all of them taken
together: it is a general observation that many  animals  go  into
shelter before  a storm comes on, and before  any of the particular
senses can be  effected.   Many people are weather-wise, as it is
vulgarly called, and, like the brutes,  are sometimes  previously
apprised of the ensuing change.  Many sleep  soundest in  a storm,
especially when attended with thunder.
   The  natural salutary actions,  arising from stimuli,  take place
both  in  animals and vegetables,  and may be  divided into three
kinds.
   Theirs* kind of  action, or self-motion, is employed simply in the
(Economical operations, by which means the  immediate functions
are carried on, and the  necessary operations performed, with the
materials the animal or vegetable is in possession of, such as growth,
support, secretion, &c.   The blood is disposed of by the actions of
the vessels, according to their specific stimulus, producing all the
above effects.   The juices of a plant are disposed of  according to
the different actions of the sap-vessels, arising also from their spe-
cific stimulus,  which is different from that of  blood-vessels, but
equally produces growth: but a vine will grow  twenty feet in one
summer, while a whale probably  does  not grow  so  much in as
many years.f
  The second kind  of action is in pursuit of external influence, and
arises from a compound of internal and external stimulus;  it is ex-

  * [i. e. Of stimuli which do not produce action through the  medium of the

  X [The insensible organic contractility of Bichat corresponds with the kind of
action which Hunter here defines.] 
216           HUNTER ON THE ANIMAL CECONOMY.
 cited by the state of the animal or vegetable, which gives the stimu-
 lus of want,  and, being completed by  external  stimulus, procures
 the proper supplies of nourishment.  It produces  motions of whole
 parts:  thus we see the Hedysarum gyrans moving its lesser foliola.
 This is an action apparently similar to breathing in  animals; though
 perhaps  it does  not  answer  the same purpose;  yet there is an
 alternate motion  in both.  The cirriferous plants, or those bearing
 tendrils or claspers, requiring  to  be  supported  by other bodies, as
 the passion-flower, briony, vine, &c, stretch out their  tendrils as it
 were at random, moving them slowly in various directions.   They
 are to lay hold of any substance  that  may be  within their reach
 that can support them, and when they come  in contact with a body
 on that side where their power of motion is  greatest they begin to
 bend in  that direction, grasp it, and continue turning round it.  We
 see motions of the same kind in the stems of the Plantce volubiles;
 some of these  turn to the left, as the Lonicera, Humulus, &c.;  some
 to me right, as the  Clitoria,  Convolvulus, &c.   They are directed
 in this  course by a lateral inclination,  which takes place only on
 one side, they having  little or no power of action on  the other.
 Those which have one mode of action pursue that principally;  but
 if prevented from doing it, their action then varies.   In the vine and
 other plants the action of the tendrils is  in different directions; and
 they may be seen at one time stretched out on one side of the  stem,
 and in twenty-four hours' time on the opposite side ; and some time
 after  in the direction of the stem itself, or in  the very  contrary di-
 rection.   These actions arise  equally  from  stimulus; it requires,
 however, different powers of action, arising from  such stimulus, to
 produce these  effects in different plants.*   The random  action  of
 the polypus is  of the same kind  as those of plants.  It elongates
 itself and throws out its tentacula, moving them  in various direc-
 tions  to catch  food;  the use of this action to  the animal, however,
 is immediate, and therefore quicker than those above described.!

  * [In the plants of the genus Cuscuta the tendrils will only twine around other
 living  plants, which shows that the phenomena of climbing plants are not expli-
 cable simply by supposing that the inclination of the  extremities of the tendrils
 or stems towards one side is a necessarily inherent law of their growth, but that
it is, as Hunter regards it, an action dependent on stimulus, which, in the case of
the Cuscuta, would seem to be a species  of organic affinity.]
  f [In comparing the motions of a polype with those of a plant, the following
 difference must be borne in mind :  the motions of a plant, like those of the parts
 of an animal after their communication with the brain has been cut off, are in-
 variably the result of external stimulus ; they follow, as it were  mechanically,
 some appreciable change in the surrounding external circumstances or influences,
 —it may be alteration of temperature, difference of light,  the application of a
chemical or mechanical stimulus; or, in an animal, loss of blood, &c.  But who-
 ever observes the actions of a living polype will see that although, for the most
 part, they may be traced to an external cause or stimulus, yet that one or more of
the tentacula are occasionally extended or retracted without the slightest appre-
 ciable change in any of the external circumstances under which the animal exists.
These motions evidently result from an internal impulse, and I would refer them to
 the presence, in the polype, of an organic element,—the nervous matter,—which 
           CROONIAN LECTURES ON MUSCULAR MOTION.       217

   The third kind of motion is from external stimulus, and consists
 principally of the motion of whole parts, which is not inconsiderable
 in vegetables, as in the Dioncea muscipula and Mimosa pudica is
 very evident; for the first, upon  being touched, closes up, and as
 it were confines the stimulating cause;  the second bends its leaves,
 from external stimulus.   This kind of motion is very  strongly illus-
 trated in  the Tragopogon,  Calendula  pluvialis, and  many other
 plants, which shut up their flowers either towards night  or when
 rain comes on ;  and in others of'different  genera which open in the
 evening, and  shut up on the approach of the sun, as different species
 of the Convolvulus, Mirabilis, &c.; and in almost  the whole class
 Diadelphia, which chiefly  consists of the winged-leaved plants,
 which shut up their foliola towards night, not expanding  them till
 morning, which is called  by Linnaeus the sleep of plants; and in
 the  motion of the footstalk of the leaf of an inverted plant, which
 twists so as to bring the surface of the leaf naturally uppermost to
 its natural position, which is remarkable in the vine, where there is
 evidently an apparatus for motion, although not a joint.
   These  actions are  similar to what arise in  many animals from
 external stimulus,  more  especially those  not endowed with  sensa-
 tion, and also to the actions of many parts of animals which do not
 appear to be  directed or stimulated by the brain and nerves;  as the
 actions  of a polypus, which has no brain,  and the peristaltic motion
 of the intestines in the more perfect animals, which does not arise
 from the stimulus of the brain and nerves.*


 is wanting in the vegetable; even in that plant, which, from the energy of its
 excitability, has been  erroneously called sensitive. There is also an essential
 difference in the nature of the  motion itself of the Mimosa and Hydra. . If we
 touch one of the feelers of the polype it recedes from the irritant by a true con-
 traction of the part within  itself; which contraction appears to  result from the
 injury experienced by that pait of  the nervous system which  is disseminated
 through the feeler touched.  In the case of the Sensitive plant there is nothing
 like that contraction of the part touched, but only an articular  plication of the
 neighbouring part  without any of the dimensions of the  irritated leaf being
 altered.]
  * [The more just comparison of the motions of plants adduced in the text would
 be with those automatic actions of whole parts which take place in animals,-but
 which result from the power possessed by the central axis of the nervous system,
 or any part of it, to transmit the action of an excitable  nervous fibril to  the ex-
 citing one with which that  central axis or part brings it  into communication: I
 apply the terms excitable and exciting to the nervous fibres with reference to their
 intermediate  relation,  as to the  muscular fibre and the  external stimulus to its
 contraction.  The excitable fibres are those usually termed sensitive; the exciting
 fibres those usually termed motive.  When the  communication between the ex-
 citable nervous fibre and the brain is entire or uninterrupted, the  latter may take
 cognizance of the excitement and sensation be produced.  When the exciting
 nervous fibres of muscular motion are  in connection with the  brain, the will,
through the brain, may excite them to action, and  this act of the brain may be
felt.  The essential character, therefore, of the actions of the brain, whether as a
recipient or transmitter of impressions, is consciousness of the action.  But this
property of consciousness is not possessed by the  spinal chord, probably not by
the medulla oblongata. Whenever, therefore, an impression received by an ex-
citable nervous fibre is transmitted through the unconscious part of the central
                                  20 
228           HUNTER ON THE  ANIMAL CECONOMY.
  The apparent difference  in  these actions would in many cases
induce us at first to believe they were  produced by different prin-
ciples ; as in many species of the same genus of plants some open
their  flowers in the day, others at night (as in the  Mesembryanthe-
mum, or  fig-marigold), similar  to that  which is the ceconomy of
some  animals, as  in  many species  of the  same genus  of moths
(Phalcena, Linn.), some fly, seek their  food, and procreate in the
day;  while  others  are  inactive and fixed  to  one spot, without
apparent motion, all day, but on the approach of night become all
at once animated, fly abroad; seek their food, and procreate.   These
actions, are  nevertheless, produced by one and the same cause.
  The owl and hawk  are  similar in  their food, yet  dissimilar in
their  times  of  catching it:  hunger  is  the  first stimulus,  animal
food is the second; light  stimulates the  one to motion, darkness
the other.*   The  action,  however, in  both  arises from  the same
principle.
  These three  kinds of motion  in plants are  influenced by various
circumstances, and sometimes  are all totally suspended.-!-   This is

axis to the exciting fibre of muscular motion, the latter phenomenon is unaccom-
panied with consciousness or  sensation.  That the spinal chord, or any segment
of it, possessed the power of transmitting an impression from an excitable  to an
exciting nervous  fibre, has been known and admitted as  a  fundamental fact in
physiology since the  experiments of Whytt, Blane, and Mayo.  To  the  latter
physiologist we are more especially indebted for the  most decisive experiments
in proof, and the clearest enunciation, of this property of the central nervous axis.
Recently the automatic animal motions resulting from this property have been
grouped together  more extensively than had before been done, and the morbid phe-
nomena resulting from them ably traced out by Dr. M. Hall. But I cannot perceive
the necessity of a distinct  class of excitable nervous fibres for transmitting an
impression to the  motive fibre through the medium of the spinal chord and brain,
and of another class of nervous fibres for transmitting an impression to the motive
fibre through the  medium of the spinal chord alone; still less can I  perceive the
necessity for one class of exciting or motive fibres for transmitting the stimulus
to the muscular fibre from the brain and spinal chord, and of another and distinct
class for transmitting a stimulus received from the Spinal chord independently of
the brain.  It remains to be seen whether  anatomy will establish the  existence
of these four classes of nervous fibres, which, so far as I  understand Dr. Hall's
hypothesis of the reflex function, are called in to account for the voluntary and
automatic and muscular motions.  There is not, however, a single phenomenon
of automatic motion in parts supplied by spinal nerves which may not be accounted
for on the demonstrated property of the central axis to transmit impressions from
 the excitable to the exciting nerves at any part where they are connected to it, inde-
pendently of the rest: and I am at a loss to understand why impressions so received
by the spinal chord should not also be  transmitted to the brain (its continuity
with that organ being uninterrupted), without the necessity of supposing a class
 of nervous fibres for conveying, in this case, the impressions to the spinal chord,
 distinct from a second class which are supposed to transmit to the motive fibres
 those  impressions which are not afterwards propagated to  the brain.   It would
 appear from the  text  that Hunter supposed that the animal motions which are
 unaccompanied by consciousness were altogether independent of the nerves; but
 they can truly be stated to be only independent of the brain.]
   * It may be supposed that there is a physical cause for the one seeing only in
 the day, the other only at night; but it is having a much more enlarged idea of
 an animal to suppose that the senses are adapted to the first principle than the
 first principle to  the senses.
   I Similar to drowned people. 
         CROONIAN LECTURES ON MUSCULAR MOTION.      219

generally produced by cold, and shows them  to be influenced by
the seasons;  often this cessation takes place when much weakened
by transplanting, &c.  I have kept a fir alive for three years with-
out the least growth.
  The second and third kind of actions commonly take place only
when the first kind of action is in full vigour, because the first must
produce the only parts which are capable of the second and third;
and these two last can only be of service to the first when  it  is in
full force, nourishing the vegetable and performing the  action of
propagation.
   These actions are almost entirely suspended in  some animals
from cold, they  being in this respect subject to seasons as  well as
plants.  This is most remarkable in the simplest in  their  construc-
tion, and becomes less and less so in  the more complicated, they
being  better adapted to the various seasons.
   The first of these kinds of action is small and insensible, although
its effects are great.  The second is considerable in both vegetables
and animals, but most so in animals.   The third is almost peculiar
 to  animals,  as  there are  very  few vegetables  visibly affected by
 external stimulus, while all animals seem to be so.
   The variety of motions is  greater in animals, and more purposes
 are answered  by them,  which  constitutes  the  great  difference
 between the actions of a vegetable and an animal; for those powers
 in  an  animal not only move themselves, but also other parts of the
 same  body, which  in  many instances are so  mechanically con-
 structed as to move common matter.   A  remarkable instance of
 this is the human hand; and it is by this means  all our various
 operations on the matter of this globe are performed.
   The first kind of action  appears to be stronger in  its power,
 although less in  quantity,* in vegetables  than in animals;  for a
 small vine was capable of sustaining and even of raising a column
 of sap 43 feet high,t while a horse's heart was only capable of sup-
 porting a  column of blood 8 feet 9  inches high: both  of which
 columns must have been  supported by the  action  of the internal
 parts, for we must suppose  the  heart equal, or  nearly so, to the
 strength or action of the other parts of the vascular  system;  and
 when we consider that the sap  of the tallest  tree must be supported
 and even raised from the root to  the most distant branches, it must
 appear that the power of such vegetables far exceeds the power of
 any animal, and indeed it is such as the texture of a vegetable only
 can support.  The power of supporting  a  leaf erect for  a whole
 day is as great an effort of action as that  of the elevator palpe-
 brarum muscle of the eye of an animal.
    If  we consider the differences in the ceconomy and the  mode of
 life of vegetables and animals, we shall find the increased  quantity

    * I  make a material difference between the power and the quantity of action.
 Some motions may be very small, yet act with great force; while others are of
 considerable extent, although very weak.
    f Vide Hale's Veg. Statics, vol. i., p. 112, Exp. 36. 
220          HUNTER ON THE ANIMAL  CECONOMY.
 of motion of the three kinds above  mentioned, and the increased
- power of the third kind in animals are only adapting them to those
 differences.
   Locomotion, for the purposes of procuring  nourishment, con-
 course of different individuals for the  propagation of the species,
 and destruction of each other, are the chief differences in  animals.
 This power, however, is not given to all animals, and those  which
 are deprived of it have their motion confined to the procuring food
 and the propagation of  their species.*  Many of these, although
 with  great impropriety, have been considered as  vegetables.
   To see if the actions of plants were affected  by .a  continuation
 of stimulus similar to those  of animals, I made  the following ex-
 periments.
   As I took  for granted that the analogy could go no further than
 as it related  to the actions  produced  by external stimuli, my ex-
 periments were only on  such  plants as exhibited actions of this
 kind.
   As those parts of plants which  are capable of the second  and
 third kinds  of motion are  in  general small, as leaves,  tendrils,
 flowers, &c, it is difficult to  discover  the  mechanism upon  which
 the motion depends:  the sensitive plant is probably the best of this
 kind that we are as yet acquainted with.
   As the motion of the petioli is confined principally to one part,
 and that differing from the others in external appearance,  which
 difference is  its increased thickness and uniformity of surface, upon
 cutting the footstalk longitudinally, as  also the stem  on which  it
 stands through its whole length, the following appearances may be
 observed:—f
   For the purpose of making my experiments I took three sensitive
 plants,  having  several  others  for any  comparative  experiments
which might  be thought necessary.  I first pitched upon  one  leaf
in each plant which was capable of the greatest motion of collaps-
ing and erection; and  behind each  of these leaves a board was
placed, on which was  marked  the greatest extent  of the two
 motions, so that the leaf was like the index or radius of an arc.
   To  have the greatest part of the day before me, I began  my
experiments at eight in the  morning, while the leaves were  in full
expansion, and I continued them till four  in the afternoon, as longer
than this  would not have been just, for  they begin to collapse of
themselves between five and six o'clock.

  * [The two sexes are also necessarily united in the same individual, as in all
 attached and pedicellate animals, from the Coralline  to the Barnacle, and in many
others of slow motions.  See note, p. 71.]
  f [A blank in the manuscript here occurs, which leaves us ignorant as to the
 result of Hunter's examination of the structure of the irritable'intumescence at
 the base of the leaf-stalks and stalklets of the Mimosa.  With his usual sagacity,
 however, he rightly refers the motive power to this  part, and it has been the
 subject of much diligent and minute investigation since these Croonian Lectures
 were read.] 
CROONIAN LECTURES ON MUSCULAR MOTION.      221
Comparative Trials of the Action and Relaxation of Three Sensitive Plants.
a.	The time.	The point they fell to.	The times they took to rise in.			The point to which they rose.
			No.l	No. 2.	No. 3.	fThe 1st and 3d rose
1.	8 o'cl'k A.M	f To the lowest point, } ■? and became sta-> ( tionary. )	Min. 51	Min. 24	Min. 32	j to the highest point, ■{ the 2d not so high, J and then became (_ stationary.
	-					
•						fThe 3d rose to the
		CTo the lowest point, }				1 highest point, the
2.	9£ A.M.	< but the second > C lower down. )	77	18	38	< 2d and 1st not so high, and then be-L came stationary. f All three rose to with-1 in a little of the
		C The second & third}				
3.	11 A.M.	< lower than lowest > ( point. j	40	30	60	<{ highest point, and | there beeame sta-^_ tionary.
4.	12 Noon.	Below lowest point.	30	30	35	( All three within a little I of the highest point.
						
						CThe 2d and 3d to
5.	40min.p.M.	Below lowest point.	60	65	30	< highest point, the (_ 1st not so high.
	2 P.M.	( 1st only below low- ) } est point. $	45	45	45	Ditto. i 3d to highest point,
	3 P.M.	Ditto.	45	45	45	< the 1st and 2d not f so high. C 1st and 2d to highest
	3£ P.M.	Below lowest point.	15	15	15	< point, 3d not so
						C high.
  From these experiments we may draw the following conclusions:
  That there is no fixed time for'the leaves of any of the plants to
 move through its course.
  That they are less affected  as  they become accustomed to the
stimulus,  but the power of collapsing  is increased (although not-
 in the  same degree), so  that they do not move through the same
 arc.
  That they require a stronger or quicker  stimulus to produce
motion after being  some time  accustomed to it, which was evi-
dently  seen  in comparing these with  others which  had not been
stimulated.
  It may also be observed that when  these plants collapse  in the
evening they have  nearly the  same  quantity of flexion as when
roughly touched at noon; but if touched after they have collapsed
from the effect of the evening, they become much more bent than
by the  same touch at noon.  This would seem to arise from a dis-
position to collapse  in the evening, and a power of increasing that
disposition and action when stimulated.
                              20* 
222
HUNTER ON THE  ANIMAL CECONOMY.
   Their collapsing more in the day, and erecting themselves less
%after a repetition of such actions, may assist in explaining the prin-
 ciple on which this depends.

                    Relaxation in  Vegetables.

   There is an action in plants which appears to  be the contrary
 of expansion; it may be considered as a relaxation, or an action
 of those parts antagonising the  others which acted  through the
 day, or at other periods, and  takes place  at  the time these other
 parts cease to act.
   This action has hitherto  been  considered as analogous to  sleep
 in animals, whereas sleep is a total loss of the sensitive principle
 and all the actions dependent  on volition for the time, and there-
 fore can only take place  in animals endowed with sensation.*   It
 is  rather  a defect  in the  animal than an action or the exertion
 of a principle.
   This action of relaxation is seen in the sensitive plant when the
 folioli close upwards and are  kept bent by the power of action  in
 the flexors, till light and some  other of its attendants affect it, when
 the extensors begin  to act, and  this  action of the  flexors ceases.
 The footstalk dropping down favours the idea  of simple relaxation ;
 but this only arises from the position of the plant, for if turned up-
 side down it still bends against its own gravity.f
   The one action is produced  by the stimulus of light, the other by
 that of darkness; for if the sensitive plant is kept in a dark room it
 will keep bent, and perhaps as long as it lives; and if one part  of
 the plant is kept in the dark and the other  in  the  light, that in the
 dark will be bent, and continue so, while that in  the light will ex-
 pand itself.
   Light and darkness become stimuli to the same plant, and  have
 much more influence over vegetables  than could  at  first be  ima-
 gined.   Many plants only grow through the day, others only grow
 after it is dark.
                     Sympathy in Vegetables.
   Sympathy is the action of one part in consequence of an applica-
 tion being made to another part, or action in another part.
   This power of action is extended to few plants, and even in these
 appears to have little variation.   It is evident  in the sensitive plant;
 for if one of the little leaves be wounded at its termination it will
 collapse immediately, as  also  its  fellow on the  other side.   This
 action runs through the whole  of the rachis of the compound leaves,
 the leaves bending regularly in pairs.

   * The polypus does not sleep.
   f [The powers which produce the depression and elevation of the leaf-stalk
 operate in a manner precisely the reverse of the flexor  and extensor muscles  in
 animals, pushing the moving part from, instead of pulling  it towards, the fixed
 point.  See Mayo's Physiology, p. 9 et seq.] 
         CROONIAN LECTURES ON MUSCULAR MOTION.       223

   If it is a middle foliole that is  wounded the same thing takes
place ;  they all collapse towards  the foot-stalk, but seldom towards
the extreme end of the leaf, and in a little time the rachis is inflected
and the whole leaf drops at the trunk.  It may be  remarked that a    *
small flexion takes place towards the  tip; but this principally arises  v
from  a disposition in the folioles,  for a middle one  cannot collapse
without pressing or folding a little on  the one next to it towards the
end of the leaf which stimulates it and makes it collapse.
   It is evident in the tendril of the vine, for these tendrils generally
divide  into two, near their ends: these two  going  out  from the
principal trunk in different directions, if one lays hold of  any body
and twines round it, the other immediately alters  its direction and
gradually approaches the same body till it  comes in contact with  it,
and then bends  round it and encircles it.  This motion, however,
is very  slowly performed.
   Sympathy in plants is very slow in producing  its  actions; the
succession of stimuli  in  them  being slow,  the consequent  actions
must  also move slowly along.
   Plants have  but one  mode  of sympathy, which  arises  from
stimulus.  Animals with  no brain or  nerves have  but one also.
Those,  however, endowed  with  sensation  have  three: they have
one mode from stimulus, one from sensation, and one compounded
of both.
   Sympathy in animals, arising from stimulus only, is slow, as  in
plants ; but sympathy from sensation  is  often very  quick.

                      MOTION IN ANIMALS.

  Muscles would seem to act by vibration, although  in  a strong
healthy man they are so  short  as not to be observed;  yet if the
muscles are  made to  act beyond their powers they plainly vibrate,
but still more plainly in weak constitutions.
  The  weaker a  muscle  is, the longer  would  seem to be the
vibrations, for if a weak person holds  anything out in his  hand it
shakes.
  In paralytic cases, whenever they are put to the  smallest action,
the vibration becomes very long, and  the less the action the shorter
the vibration.
  Fear also  increases the  vibration in proportion as it weakens the
muscle.*

  * [The first  part of Dr. Wollaston's Croonian Lecture for  1809 is devoted  to
the illustration of an opinion on the nature of  muscular motion, corresponding
with that which Hunter has above enunciated. Dr. Wollaston, as is well-known,    *
was led to infer that each act of contraction, apparently single, consisted  in
reality of a great number of contractions, repeated at short intervals, by reflecting
on the sound perceived upon inserting the extremity of the finger into the ear.
This sound, which resembles that of carriages at some distance  passing rapidly
over a pavement, is not perceived when the force applied to  stop the ear  is not
muscular, unless the action of some distant muscle be communicated through
some medium capable of conveying its vihrations.  From experiment, associated 
224          HUNTER ON THE ANIMAL CECONOMY.
                 The Causes of Action in Muscles.

  The actions of muscles have been hitherto attributed to the nerves
as a cause; the mode of action of  the nerves, however, not  being
known, most physiologists have thought  themselves  obliged either
to make a  new  hypothesis, or support an  old  one; in all which
they make it mechanical, depending either  upon the  motion of a
fluid, or the vibration of a solid, or vapour ;  but there is not a single
known fact attending the nervous system which could either give
rise to, or support, these hypotheses, except  the  distance  between
the seat of the will and a voluntary muscle;  and  they have  conse-
quently been such as few thinking men could adopt.
  As the brain and  voluntary muscles  are, with respect  to  our
senses, in two different  places, and are connected together by the
nerves, it might be supposed there was some fluid in motion that
would convey the impression to the mind, or the will of the mind
to the voluntary muscles;  but  these informations are very probably
the effects of sympathy.
  I am  afraid we can go no further in the investigation of the cause
of the action of muscles than  by observing  the  phenomena which
happen, and these all lead us to one cause of action.
  The  visible  external  cause of the action of  a muscle is  called
' stimulus,' and  it is reasonable to suppose that all  causes of such
action are similar.   This, however, may admit of dispute, the heart
certainly having no visible stimulus for its motion, except the being
called upon, by the sympathy which subsists  between the combined
powers of the animal ceconomy, to exert itself in their favour, which
will not account for the heart's motion when removed from that
connexion.
  The great question has hitherto been, whether a muscle is suscepti-
ble  of impression without the medium of a nerve, or whether a nerve
is in all cases necessary to its being called into action ; for a stimulus
must either affect the nerve which affects the muscle, or the muscu-
lar  fibre itself  must be susceptible of immediate  impression from
the stimulus.
  A muscle would appear to be capable of  being affected  in both
ways, for many animals certainly  exist without nerves, and plants
are susceptible  of stimulus where it must be immediate, they never
having been supposed to have nerves.*  It is also evident in ani-

with the above observation, Dr. Wollaston concluded that the vibratory alterna-
tions recur between twenty and thirty times in a second, varying in proportion to
the degree of force exerted by the muscle ; the greatest number being estimated
at thirty-five vibrations in a second, and the lowest at fifteen.  The more obvious
illustrations of this mode of muscular action, presented by the aged and infirm,
are also adduced by Dr. Wollaston, who, without doubt, was quite unconscious
of the conclusion previously drawn by Hunter from the same phenomena.]
  * [Those who admit that a muscle is susceptible of stimulus only through the
medium of the nervous matter blended with its substance, do not scruple to ascribe 
           CROONIAN LECTURES ON MUSCULAR MOTION.       225

 mals with nerves that by stimulating a nerve the  muscle  to which
 it goes will be immediately thrown into action, the nerve becoming
 the immediate stimulant, so that a muscular fibre may be stimulated
 by a nerve as well as by any other impression.
   The modes of stimulating  a muscle will  be different according
 to the  nature of the animal or of the muscle.   In the«more simple
 animals they will  be few,  increasing  as the animal is more  com-
 plicated.
   The first  kind  of stimulus is that  common  to  all  animals and
 vegetables, which regulates the internal machine, producing growth,
 preparing the parts of generation, &c, &c.
   The second  is  the internal  stimulus, which respects  external
 matter for the  support  and  continuance  of the first, as that pro-
 ducing breathing,  hunger,  the desire of propagating the  species;
 all of  which are common  to vegetables as well as animals, and
 require the assistance of a third kind to complete the action.
   Vegetables are supposed with  great reason to have an action
 analogous to  breathing, for the same kind of air which kills animals
 which do breathe, certainly kills vegetables also.*   Vegetables im-
 bibe nourishment, which action arises from the same stimulus  as in
 animals.   They also require the stimulus of certain operations  to be
 performed upon them by external  matter to enable them to propa-
 gate.   This external  matter is either some other part of the same
 plant, as  in  the Marchantia polymorphia calyce  decemfido, which
 has the filaments almost  constantly in motion striking the antherse.t

 nervous or sensitive globules to vegetables.  But they here create the necessity
 which an undemonstrable organ is called in to supply.   Now the more simple
 and philosophical mode of considering this question seems to be to examine whether
 the moving organs are stimulated in any new, distinct, and additional manner in
 those  organized beings in which nerves have been detected; and if it be found
 that they all manifest spontaneous actions,—motions of parts independent of any
 external stimulus,—a phenomenon which has never been witnessed in  any plant,
 then the next step would be to determine  by experiment the relations subsisting
 between  the new function and  the superadded organ.  The irritable fibre does
 not contract in a different manner when stimulated by the will than when stimu-
 lated-mechanically out of the body; nerves, it is true, convey impressions which
 excite action, and are essential to the application of the voluntary stimulus, but
 not, therefore, to the muscular contraction.  Hence, when we come to account
 for the cause of the spontaneous actions in animals in which no nerves have been
 detected, we are justified, by analogy, in attributing the spontaneous stimulus to
 the presence of undemonstrable nervous matter.  But in the case of plants, if we
 attribute  the contractions to anything but the irritability of the moving  parts
 themselves, we must first hypothetically assume that nerves are necessary for the
 action, and then  gratuitously infer their existence.  This, however, only leads to
 a greater difficulty, to account, viz., for the non-existence of spontaneous motions
 in those organized beings to which nerves are, in the above theory, attributed.]
  * [As azote, hydrogen, or any gas deprived of carbon and oxygen; for though
 vegetables in health and sunshine give out oxygen, they absorb that gas, and emit
carbon, but in less proportion, during the night.]
  j- [In the barberry the filaments supporting the mature anther, when touched,
bend  towards the germen. In  the tiger-lily the female part  of the  flower  is
endowed with irritability, and the style bends first to one stamen, then to another.] 
226          HUNTER ON THE ANIMAL CECONOMY.
The filaments of the flosculee of the thistle produce the same effect,
or it  is done by some foreign stimulus, as the wind, driving the
pollen of the male  plants against the germina of females.*   Most
animals perform these actions  themselves, yet in both animals and
vegetables a similar stimulus is necessary.
  The third Jiind of stimulus is from external or extraneous matter
immediately applied to the part, which is also common  to animals
and vegetables.
  The fourth kind of stimulus  arises from  the nerves,  which  we
may reckon twofold; one in  consequence of the nerves being im-
pressed by external  matter, the other from their being impressed by
the brain, or  sensorium.
  This is peculiar to animals,  many of them receiving intelligence
from without, which becomes  the regulator of their actions towards
that matter which gives the intelligence. This leads us immediately
to voluntary actions.
  The actions  of muscles have hitherto only  been considered by
physiologists  in the  more perfect animals where this (the voluntary
or nervous stimulus), is given, which becomes a different cause of
action from  those found in other animals and vegetables.
  Those actions where the mind, being made sensible of them, may
be considered as a  cause, are  called  voluntary  actions; and those
actions over which  the mind  has no  influence, and about which it
is not in the least consulted, are called involuntary actions.  The
actions of the muscles which go on without the influence of the
mind, but can be restrained, increased, or stopped by the mind, are
called mixed.  There  are also actions which may be allowed to
arise from a peculiarity in the state of mind, but not dependent on
the will: these are common to both  the  voluntary and involuntary
muscles.  Thus an involuntary muscle,  as  the  heart, increases its
strokes, and the voluntary muscles of the hands, legs, tongue, &c,
tremble when the mind is agitated by anger, fear, &c.   These four
kinds of action  not  only appear to arise  from different causes, but
produce different phenomena.
   The first kind, or voluntary motions,  last only for stated times,
beyond which they  cannot  go, the muscles  either losing the power
altogether, or the mind becoming incapable of stimulating them ; by
which means a cessation of  action  takes  place, which indeed  is
necessary for the preservation of the animal.   For these actions,
too long continued, weaken, hurt or destroy the body ; and there-
fore the mind which is under  no  restriction is thus prevented from
continuing the action.  We have this beautifully illustrated in some
of the mixed motions: for where their involuntary motions are em-
ployed for the preservation of the animal, as in  breathing, they are
constant; and where the stimulus  of necessity does not constantly

   * The antherae of vegetables requires some motion to make them burst; some
have not the power of producing this motion, but if the power is given they burst
immediately.   A blast of wind is often necessary, and in such plants propagation
does not go On well in  a calm place. 
         CROONIAN LECTURES ON MUSCULAR MOTION.      227

take place they rest, as in the  stomach, levator palpebrarum, &c.;
but if we voluntarily increase  the actions of these they soon tire.
   The natural involuntary actions of  muscles  are such as never
tire, while the voluntary  always do; and we may observe  that the
muscles which are under the  influence of  both  are  never  tired of
their involuntary actions, while they are of their voluntary.  This
we might suppose was owing  to this  property being stamped upon
them at first, and for very wise purposes; but it rather appears to
be a property arising from the mode of impression, viz., not  being
impressed by the will, but probably acting from a general impression
in the machine, viz., from general principles; whereas the voluntary
 actions are caused by a peculiar impression of the will, and the mus-
cles are so constituted as to tire  of that impression, or rather be-
come incapable of acting, which  gives the sensation called tired.
But this is carried further, for in muscles that are entirely at the com-
 mand of the will, if they take on involuntary actions they never tire.
 For instance, Lord L----'s hands are almost perpetually in motion,
 and he never feels the sensation in them of being  tired.  When he
 is asleep his hands, &c, are perfectly at rest; but when he wakes,
 in a little time they begin to move.
   We tire of voluntary actions whether of voluntary parts or  of
 parts that commonly act involuntarily, as the muscles of respiration.
 Tiring of action feels  to the mind to  be in  the muscles themselves,
 but I imagine it must  be in the mind, although it is  referred to the
 muscles; for we cannot  suppose that  the mode of action of a mus-
 cle  directed by the will  is different from the mode  of action when
 not directed by the will.  This is not a tiring of the will itself, but
 probably a tiring of the  action of  the nerves of the will; and as the
 actions of these nerves  is always referred to the part of their des-
 tination, the tiring is also referred there.
   The second kind are  the involuntary actions, which are lasting,
 as the parts themselves : these are always fit for action; and if they
 are inactive, it does not arise from the want of power in the part to
 act, but from a cessation of the stimulus, which cessation takes place
 whenever the action, from peculiar circumstances, is become un-
 necessary.  Such actions are naturally so circumstanced as to be
 constantly wanted, being for the  preservation of the animal, as the
 motion of the heart.
    The nerves  are only to be considered  as conductors  carrying
 impressions from every part  of the body  to  the brain, or carrying
 the command of the will  to  those muscles whose actions can only
 be  employed about such external  objects as can affect the mind ; but
 those parts whose actions are unknown to the mind appear not to
 be affected at  all by  the will.
    That the nerves are  the principal agents between the  mind and
 the parts would appear from circumstances  respecting their com-
 parative size;  for all those parts which convey a strong sensation,
 or  are intended to perform extraordinary voluntary actions, have
  large nerves; while those parts of animals  which neither give intel- 
228          HUNTER ON THE ANIMAL CECONOMY.
ligence to the mind of their actions, nor are under the influence of
the mind, have very small nerves.   A stronger instance of this can-
not be given than the electric organ of the torpedo, where the power
of giving or restraining the shock depends upon the will: the actions
are strong and violent, for he can  soon exhaust himself by them;
and the nerves which convey the power of the mind exceed, com-
pared with the size of the animal, in bulk the  nerves  in any organ
of any other known animal.  It is a part whose actions, its growth
excepted, depend entirely upon the will, having no power of action
of its own; the communication between the will and the organ is
large in the same manner as the communication between the senses
in general and the brain.is large.
   The voluntary muscles  have large nerves  to  command  the
action of the muscle, which is independent of  the will, although in
some  degree subservient to  it; but they are not so large as those
of the senses or electric organs, where they give the part its whole
action.
   A nerve being cut going to a voluntary  muscle, the muscle can-
not obey the will, and  thereby loses its voluntary actions;  but it
may be stimulated into action by immediate impression from other
causes, as electricity.
   The voluntary and involuntary muscles  having their quantity of
motion in an inverted  proportion  to their quantity of nerves, is a
strong  argument against the nerves being the cause of muscular
motion.
   If it is asked why the  involuntary parts  have nerves at all,  the
answer may be given that it is not for their common  actions, but
to keep  up the connexion between  the whole, for without them an
animal wTould become two  distinct  machines, and one might be
acting  very contradictorily  to the other; but by  the intercourse
between  the will and voluntary parts, between the voluntary and
involuntary, and also between these last and the mind, an universal
and uniform agreement or regulation is kept  up, which communi-
cation  produces one kind of sympathy.  This connexion between
the living principle  and the sensitive produces a compound action,
which becomes the cause of the instinctive principle in animals.
  Muscles are either employed upon the internal operations of the
animal, as the heart, muscles of respiration,  stomach, intestines, &c,
or upon  external matter for the  support  of  both, as those of the
extremities.
  The first of these are nearly of the  same strength  in the robust
strong man and  the small woman or man, if equally healthy; and
it is right it should be so, for the  small man has nearly the same
resistance to  cope  with; but it is the  others which constitute the
strong or weak man.
  The power of muscles which are influenced  by the will, although
they have a common power of action with those independent of the
will, sooner lose their powers than those  which are  wholly invo-
luntary, as the  heart,  stomach, bladder, blood-vessels, &c, which 
         CROONIAN LECTURES ON MUSCULAR MOTION.      229

would seem  to  show that the power of simple life lasts after the
will is no more.
  We might, naturally  suppose  that the voluntary muscles have
nearly the same quantity of power of  action as the involuntary;
but upon considering several circumstances, we should rather con-
ceive the contrary ; for when we consider the power by which the
colon of a horse propels  such a load of solid  contents, we can
hardly conceive the power of any voluntary muscle of the same
thickness equal  to it.   For, as voluntary motion arises from two
causes, or has two causes of action, the moment one of these ceases,
the power which remains is  either not so strong originally as the
whole power of the involuntary muscle  which has only this princi-
ple of action, or  not so strong, from want of habit, not having been
always employed as a principle of action in them.
   It is not clear  to  me  but that every muscle has a sphinctorial
power of contraction  so as to bring them to the middle state.   This
we may  see in the temporal muscles ; for by opening the jaws the
muscle sinks, and by  leaving the jaw to itself, not acting with it in
the least, the jaw rises and  the muscle in part fills up, so that the
jaw is suspended by the half action of  the muscle ; however, this
power may be much  more in some muscles than others.
   The great variety of causes of muscular motion  make it almost
inexplicable: they may be said to be three,—the will, passions of
the mind, and external stimuli.   Those actions arising from the
will and the  mind appear to be most simple,  because they are
totally unintelligible; but  those arising  from external  stimuli are
either voluntary or involuntary, for a muscle  that acts by the com-
mand of the will at one time is also capable of being thrown into
action by a particular state of mind or external stimulus.
   Those actions which arise from the  will have reason and habit
for their continuance; they are such as arise out of imitation, rea-
soning, and all the powers collected by  the senses.
   Those actions which arise from the  mind belong mostly to the
passions, which affect  more muscles of  the body than the will;
perhaps  there is not a muscular, fibre in the whole animal machine
but is at different times affected according to the different affections
of the mind, every  different state  of  mind having its particular
muscles  to stimulate.
   Upon many of these occasions reason  is introduced, which is
provided by this state  of mind  to call in the assistance of other
muscles, to act according to that state, either to  bring about an
increased action which will destroy itself, or to prevent the increase
 and continuance of those  actions.
   From extraneous stimuli arise all our internal insensible actions,
 and  these depend upon  the principle  of  simple life, upon which
depends also the action of medicines; and health is only the right
action of such parts.
   Some muscles must  be put upon the stretch, and they will con-
 tinue their action far beyond the easy point,  or that which was so
                                21 
230          HUNTER ON THE ANIMAL CECONOMY.
before this action, as the stomach, intestines, and bladder.   Others
wait to be stretched, as the uterus;  this, however, is not the cause
of its contracting again, it is only putting it in a state to act when
another cause  takes  place, as a miscarriage or fcetus at the full
time. This is nearly opposite to the other, for what endeavours to
empty or relax  the  uterus becomes the  cause of its  contraction,
not what stretches it.
  Voluntary actions, when very violent, produce  involuntary, as
the cramp,  from dancing, swimming, &c.
  We feel  every involuntary action of a voluntary muscle, while
we do not feel the voluntary actions ; nor do we feel the actions of
an involuntary muscle.  When such actions are slight we only feel
them as little convulsions, contractions in different parts of the body,
called creeping in the flesh, or quivering in  the eyelids ; but when
these become violent,  as in cramps or spasms, then the sensation is
pain.
  Voluntary muscles, the  stronger they are, the more they are at
the command of the will;  and the weaker they are the more they
seem independent of the power of the will, and seem to be either at
their own command, or at that of the nerve.   Strong people are less
subject to spasms than weak, which may  perhaps arise  from cus-
tom ; the strong muscles  being more  healthy, are oftener in use,
and therefore become more at the command of the  will.
  Women, children, and sick men are subject to fits, for the reason
just mentioned ;  perhaps also diseases of the uterus, for the same
reason, are the cause  of spasmodic  complaints, it being very little
at the command of the will, but of other circumstances ;  and from
this disposition draws  in other parts  by consent, and so brings on
general spasm.
   Voluntary muscles  always become tired when long continued in
the same action, which accounts for animals tiring sooner by being
kept in one position than if allowed to move; and we find a man
can hardly stand five minutes  in  one position ; he  never stands
equally upon both legs, but upon one as a  base, the  other as a prop,
so as to be able  to shift his legs as they tire.
   Animals,  also, by  moving or producing alternate  motions  by
their muscles, can go on for a considerable time, but their alternate
motion must not be quick,  as it always requires a certain time for
muscles to  regain the  power which they lost in action, and if the
alternate motion becomes quick and violent, it may tire sooner .than
constant motion.
   The voluntary actions of young  animals  are not so  strong, and
are much less lasting  than those of middle age ; that strength they
have they are not capable  of employing for any great  continuance
without tiring, especially in actions where a considerable force is
required.
   Thus we have young horses soon fatigued with labour, which
the same horses will easily perform some years after.   This ability
in the older horse does not arise entirely from a naturally  greater
degree of strength, joined  with a natural capability of continuance, 
         CROONIAN LECTURES ON MUSCULAR MOTION.      231

but in some degree from an acquired strength from employment,
and a capacity of endurance from the habit of action.  This might
be thought sufficient to account for the whole difference,but dealers
in horses affirm that one of seven and one of four years old, having
equally done no work, shall  not be equal in their continuance of it.
In riding they also  give weight  according to age, and  the  aged
horse always carries the greatest weight, if other parts are equal.*
   When an animal is at its full strength is not easily ascertained,
but it cannot be while growing ; it must have arrived at its full ex-
tent, and perhaps it is even  necessary to have been  some  time in
that state.
   The involuntary actions  are  stronger before this period than
after ; this is perhaps necessary for the  animal's growth.
   Besides the decrease  in the size of a muscle from an atrophy,
etc., and the restoration of them again to their natural size, which
is disease and health, there is  an increase which  accompanies the
whole body, till it arrives at its full size, when the  whole seems to
rest, except the muscles.
   How long the muscles continue in this full size is  not easily ascer-
tained, but when  old age begins to come on, the muscles begin to
decay;  but not becoming pale and flabby, like  a diseased muscle,
but retaining their redness and sound  appearance.
   A person grows thinner after a certain age, but not in proportion
to the decrease of size of the muscles, for the interstices between
the bundles of fibres, and also  between the muscles themselves, are
loaded with fat, and this takes place so constantly that an old man
may be distinguished from a young one from only seeing the mus-
cles, and the fat mixed with  them.
   Muscles in old  people lose their quantity of  contraction, and the
joints are therefore never moved  to their full extent.  This  is the
loss of only the extreme motion, which is weak, and therefore may
be supposed to arise from weakness alone; but I do not  think this
effect is produced in young people from weakness.
   An old man stands with his knees, thighs, and all his joints bent,
not being able to  bring  himself to the upright position.
   The actions of the body that are  both involuntary and  voluntary
are some of the most beautiful circumstances in  the machine.  I
believe the muscles of respiration are the only perfect instances of
it.  The sphincters also have both ;  but in them it  would seem to
be an involuntary continuation of an action which is voluntary.
   Fresh air was  necessary for our existence, and  it  was therefore
necessary that it  should be  regulated by some other  principle than
that of  the will;  for it is necessary when we sleep, and also  when
we will the contrary.  Therefore our will has its limits of power
over  the  involuntary actions, and the  involuntary also have their
limits over the actions  of the will; each therefore can only go a
certain  length in  opposition  to the other.
   As all animals which breathe air are probably endowed with the
* How accurate these gentlemen are I don't know. 
232
HUNTER ON THE ANIMAL CECONOMY.
power of forming sounds, and as air  is in common necessary for
such an  effect, Nature has made this air answer the purpose of
sound as well as of life.  For the purposes of life it was necessary
the action should be kept pretty regularly constant, and  therefore
involuntary, because it required  too much attention of the will to
keep up the necessary action, and the will is not always in a state
to attend  to it; but for the purposes of sound  it was  necessary it
should be at the command of the will, for  sound is in some degree
arbitrary: for although often attended or caused  by a natural pro-
pensity at the time, yet it can be avoided, as in crying.  Vocal
sounds, however, do  not entirely interfere  with inspiration and ex-
piration ; it is performed by the last, which must have been preceded
by the first, although not with the same ease.
  Many other actions of the body interfere with involuntary respi-
ration ; all violent exertions of the body are  a check upon it; but
then in proportion to the intended exertion,  the voluntary supersedes
the involuntary, and they take in a proportionate quantity of air;
but, both in sounds and exercise, if continued, the  stimulus of neces-
sity for a repetition of respiration takes place, and  the  person is
obliged to take in a fresh supply of air, which again answers the
former purpose.


                     The Colour of Muscles.
  Most parts of an animal body are white, and when they have any
other  colour it generally arises from some  adventitious  though
necessary matter, as the pigment  of the eye,  which in  many
persons is black, in  some green, in  others white, &c.; also the
pigment of the skin, which in many people  is dusky in its colour.
  A muscle in all animals is in itself white, and its red colour found
in living animals, and also immediately after death, arises from the
blood ; for if a red muscle be steeped in water it will become white;
or if the  arteries of a part which has red muscles be injected with
water till  it  returns by the veins, the muscles soon  become white.
A red  muscle exposed to  the air  loses the Modena red, becoming
florid.                                                       5
  As the colour of  muscles arises  from the blood  in their vessels,
the muscles of every animal must  have the same colour with the
blood; if  the blood  is red, the muscle will be  more  or  less so,
according to its quantity ; for in sick or unhealthy people they are

  If the blood is of any other colour the muscle will be tinged with
that colour, and also in proportion to  the quantity of the blood.
  All muscles  however, have not the colour of the  blood, for
many animals having red blood have their muscles almost white;
and even in  the human body many muscles are much redder than
others.   The muscles of an  arm or  leg  are  much redder  than
those  of the stomach  or  intestines; those of the face are much
paler than the temporal or masseter, although nearly in the same
situation. 
CROONIAN LECTURES ON MUSCULAR MOTION.      233
  The  muscles of  quadrupeds are not equally red, there being a
great difference between those of a hare and rabbit.
  The difference in the colour of muscles in the same animal, and
in different animals of the  same order, is  very remarkable, but is
equally to  be observed in another order of animals, viz., fowls.
  The  blood  in fowls is red; there are few, however, in which
some muscles are not much redder  than others,  and in some birds
they shall  be  almost wholly red, as in the' black cock, while in
others they shall be nearly all pale, as in the turkey.  The muscles
of birds are more  generally pale than those of quadrupeds, from
their having a smaller proportion of red blood, and that blood being
more partially distributed.
  The muscles in  frogs, snakes, tortoises, &c, are generally pale,
from  their having  a  still smaller quantity of red blood, and that
quantity more confined to the vital parts than in birds.   .
  The muscular parts in fish are generally white, although I believe
they have all red blood, but in smaller quantity than even frogs and
snakes, so  that the motion of red  blood in them is much confined in
its extent, appearing  to go  no further than those parts which  are
essential to life.
  The muscles of many  animals  of a still inferior order are gener-
ally pale;  the blood in them being  not  apparently of any colour,
and in some almost transparent, as in the lobster, oyster, snail, &c.;
and in this order of animals, if the blood is of any determined colour,
it is generally so confined in its motion, not  running minutely into
parts, that  they are hardly tinged with it, as in the slug, which is
black, although the blood is of a milk  white.   The earth-worm,
however, is an exception to  these general observations  on the more
imperfect animals, for it has a great deal of red blood, which is seen
through the whole body of the animal, from the external covering
being pretty transparent.
  The red blood in a  muscle is in  proportion  as the red blood in
the animal is to the quantity of muscle; and also  in proportion to
the quantity of action in the muscle  and the quantity of red blood
taken together.
  The blood in the more perfect class of animals, as man and qua-
drupeds, and in which class whales  are  also included,  is in greater
quantity, and more  loaded with red particles, than in other inferior
orders;* therefore  the muscles are  in  general redder, and  the
quantity of blood in this order of  animals, and perhaps every other
order in which they have  red  blood, is rendered greater by in-
creasing the action of the muscles, the blood  being driven or  ex-
tended  further into those parts by  their increased action.  This
happens  commonly in  voluntary muscles only ; the involuntary,

  * [From the numerous  experiments of MM. Prevost and Dumas (Examen du
Sang, Bibl. Uni. de Genev., t. xvii.), it would appear that the red globules  and
fibrin are  most abundant in the blood of birds, in which respiration is most active
and animal temperature highest.]
                              21* 
234          HUNTER ON THE ANIMAL CECONOMY.
being employed in uses at all times equally necessary, are even and
constant in their action.
   Muscles much at rest are pale, as  in animals just come into  the
world, before the muscles have had much action, except the heart,
which has been acting from the beginning ; and all the muscles ot
a young animal, except the diaphragm, may be kept  pale by keep-
ing the animal in a state of rest,* for in that state the blood does not
pass far into the muscle; but  as the animal grows up,  the  muscles
become redder  and  redder, especially if they are allowed action
by the animal taking exercise, and  nearly  in proportion to-that
exercise.
   This, however, is not universally the case ; for the natural actions
of a hare and rabbit are not  very different, yet the muscles  of a
hare are very red, and  those of a rabbit pale; whereas I do  not
believe it ppssible by rest alone to make  a hare's pale, although by
rest they will  become proportionably paler.f
   This difference in animals so nearly allied would seem  to arise
from an original law  in  their nature; for although a hare may not
have a greater quantity of motion  in  common, yet it is formed to
be always in  such a  state as  if it really had, that it may be  con-
stantly prepared to undergo such motion.   The rabbit has  no occa-
sion for such  a state of muscle, its sphere of action being much
confined, and  it is even not intended to run fast.
   In an inferior order of animals, where the quantity of red blood
is  not so great, and the destruction of voluntary action  not nearly
equal through the whole muscular mass, we find a great difference
in  the colour of muscles.
   A bird has  two kinds of progressive  motion, flying and walk-
ing.   Some principally fly, others walk,J  and many perform  both
equally.
   In the walking bird the muscles of the leg are the reddest, as in
the pheasant,  partridge, and common fowl.  In the flying  bird the
muscles  of the wing  are  the  reddest, as  in  the  swallow  and
woodcock.^
   In the frog,  snake, turtle, alligator, &c, there is  but little action,
and the  muscles are  nearly equally employed through the whole
animal except the heart; so that there is not that difference  in colour
in the  muscles of the  same  animal, or  of any two of  this order,
although in many it may be observable.
   In fish we find a good deal of difference in the colour of muscles,
and the heart, which is in constant action, is in them as red as any

  * This becomes a distinguishing mark between the hares of a barren mountain-
ous country and a rich flat one.
  f Such is the method of preserving veal white, for the proportional quantity of
red blood is not allowed to increase or go far from the heart.
   X Swimming in fowls I consider as walking, both being actions of the legs.
   § Epicures are sensible of this; therefore white veal,°the leg of woodcocks,
are delicious bits, and the feeders of domestic fowls indulge them.   They rob the
appetite, however, to please the eye, the flavour generally being in the muscles of
action. 
CROONIAN LECTURES ON MUSCULAR MOTION.      235
other animal.*   The  natural  history of fish is very little  known,
but what variety there is we  may  attribute  to the cause above
mentioned.f
   The actions of the more inferior orders of animals we shall not at
present enter into.
   From the above observations we may conclude that red blood,
in those animals that have it, is of essential use to muscular con-
traction.
   That the quantity of red blood brought to a muscle  is of service
in its action  is plain; for a muscle become paralytic from an injury
to the nerve, or an  anchylosis in the joint preventing its having con-
tracted  for many years, is found white,  small, and somewhat  liga-
mentous, retaining however a degree of transparency and gelatinous
consistence, so that a muscle may become paralytic from too much
rest alone.
   The wasting of a limb which is seen externally takes place  prin-
cipally in the  muscles, more  especially where  they are paralytic
from an anchylosed joint; in that case  the muscles alone  c.an be
supposed to  be affected, they alone being concerned in the  motion;
but where it arises from a defect in the  nervous system, that defect
may be in all the nerves of the limb, and therefore all the parts may
suffer alike.

                       Swelling of Muscles.

   We may suppose that the blood is of great use in muscular con-
traction ; for in violent and frequent  actions  of the muscles  they
swell and become considerably larger, not when in action only, but
when relaxed immediately after the action, and will continue swelled
for some time.
   This  swelling does not come on till the muscle is tired of acting;
this must be  from a greater influx of blood at that time, or that the
action does not  let the blood pass so freely through the veins.   It
must be owing to something of this kind which happens to animals
which use much violent exercise, and are killed during the action,
that they are redder, fuller, and eat much tenderer, but do not keep
so lono-.  There is a  material  difference between a hare or deer
that is°hot and one run down by dogs.

  * [Most of the above facts, with their physiological inferences, were known to
Grew, who alludes to them in the following  digression while  describing  the
digestive  organs of the bird : " And as the strong and continual motion  of all
these muscles is taught, us from their structure, so likewise from their red colour,
which, especially in the grinders" (the lateral muscles of the gizzard,) " is in-
tense. Hence in a fish the muscles which move the fins are usually red although
the rest of the  flesh is very white ; and so the leg of a domestic fowl.  Whereas
the wings also  of a wild fowl are of the same colour.  So likewise the flesh of a
driven calf, or of a hare, though that of a coney be white.  And that which comes
nearer the heart in all creatures having the like continual motion is of a red
colour!"__Anatomy of Stomachs and Guts, fol., p. 41;  1681.]
  f [See note,  p. 170.] 
236          HUNTER ON THE ANIMAL CECONOMY.
   Muscles not only become really larger by acting, but also become
larger in the time of acting, and for  that  time only,  subsiding
gradually after the action is over:  this increase is in proportion to
the violence of the action at the time, and appears to go on till they
are tired, and is probably one cause of their being so.
   In order to ascertain this fact as much as possible, I made the
following experiments.  Immediately  after getting up in the morn-
ing,  having  used  my arm  as little  as  possible,  I  measured  the
circumference  of  my right  arm  across  the belly of the  biceps
flexor, while  in the  relaxed state of  all  the muscles of  this part,
and found it measured ten  inches and  a half.  I then bent the
fore arm, in which action the biceps being contracted, I  measured
it  again at the same place, and found  it twelve  inches  one-eighth,
so that this part of the arm had gained one inch and five-eighths.
   After having thus ascertained the size of the arm, both when all
the muscles  were  relaxed,  and  also when  contracted,  I next
worked  an air-pump for  about ten minutes  with considerable
violence,  when  my  arm became  quite  tired.  On repeating the
above  mensurations I found  my arm in the relaxed state eleven
inches and five-eighths, and in the bent state twelve inches and five-
eighths ;  so that the arm, by acting ten  minutes,  had acquired an
increase of six-eighths of an inch in circumference even in the
relaxed state of the  muscles, and four-eighths in the contracted
state.
   That the calf of the leg swells towards night is  a common obser-
vation; and 1 suppose it is principally owing to its having acted so
much through the day.
   That the swelling in such cases  is in the muscles themselves is
evident from  the stiffness  felt in acting with tired muscles.
   What produces  this temporary increase in  the muscle ?  It is
probable that an extravasation of  fluids  has taken  place, and the
weakness induced in the  muscles  in consequence of their  having
acted  more than usual,  and with greater  force, is the  cause of
extravasation.

                 Effects of Habit on Muscles.

   Muscles are  capable  of  being improved  and   increased in
different  ways by exercise, or employing the muscle  much in its
natural functions.
   This improvement in action is most observable in the  muscles
of volition, as it is in consequence of the will that they become
more familiar with the actions;  and also  they are more subjected
to a  variety of action,  sometimes acting  strongly, at others not
at all.
   The stimulus of the will never loses its influence by habit or  by
becoming familiar, but these stimuli  may be called arbitrary or
accidental, foreign, &c.   Muscles  not only improve in one parti-
cular, but in every respect whatever. 
CROONIAN LECTURES ON MUSCULAR MOTION.      237
  One improvement voluntary muscles  acquire from habit is  the
readiness with which they take up their  own actions, the will fre-
quently only having to set them  a going;  there are instances of
people playing tunes without attending to the notes or even thinking
of the tunes.
  From this facility of obeying the will in  beginning actions, and
of repeating actions they have been  accustomed  to, with  the
greatest variety of  motions, in the voluntary muscles, particularly
in man, and  also from  the frequent employment  in any actions,
muscles acquire a facility in obeying the mind in the performance
of actions they had never tried before,  going  hand in hand with
the mind; for  as  the mind,  when  it  sets the  body to perform
actions, acquires a facility in immediately employing  the  proper
muscles, they obey directly, and this even in actions they never
performed before.
  A man will  learn one trade  much  more  readily if he  knows
another, than if he  knew no trade at all.
  The  habit of acting in a muscle, especially when employed in
considerable   exertions,  increases  the necessity  of  becoming
stronger, which necessity, acting as a stimulus  upon the muscles,
becomes a real cause of increase of size, which  augments their
strength.
  This effect is so evident, that painters and  sculptors, as well as
physiologists,  have  observed  it.   We  have Charon and Vulcan
always represented with large shoulders, brawny  arms, and their
lower extremities small,  and apparently  disproportioned.
  This effect is  still more nicely marked by the difference between
the right arm and the left; the right being generally employed in
preference, and more particularly in great exertions, is therefore
the largest and strongest.  People who  play much  at tennis, where
the ball is always struck with the right  hand, have that arm much
thicker and stronger than the left; therefore a man originally well-
proportioned  shall lose that proportion  by being employed  in  any
action that does not require the whole body.  From these facts it
must appear, that if every animal was perfectly made, with  respect
to any standard proportion of its parts,  that few would  be allowed
to  grow to  that standard,  because few  animals exert all their
muscles equally, there being in most some circumstances in  life
which oblige them  to exert one set of muscles more than another.
This is probably more the case in  man  than  in any other animal,
and also in him less determined  to any one set of muscles more
than  another;  it, however, also  takes place  in animals, as there
will be a considerable difference in  the muscles of two birds'
breasts of the same species, one being allowed to fly, and the other
kept in a cage.
  The increase in the voluntary  muscles appears not to be without
limitation, and indeed if it was we might see them increase  beyond
conception.  What principle  sets bounds to this increase from ac-
tion is not known; the circumstance of these muscles  tiring  may
become a cause. 
238          HUNTER ON THE ANIMAL CECONOMY.
  This increase is not confined to the voluntary muscles, for the in-
voluntary, when obliged from any  circumstance  to  act with un-
common force, also enlarge, and become stronger, and  in a much
greater degree than the  voluntary.
  The bladder has been found exceedingly thickened in its muscular
coat where there are either strictures in the urethra or stones in
the bladder, for in this last complaint,  although it discharges  the
urine, yet it continues to act with more violence than usual, being
irritated by  the  stone, which it cannot expel.  I  have seen it in-
creased to three  times its natural thickness.*
  Increase of thickness in the auricles  and ventricles of the heart,
in consequence of an aneurism in the arch of the aorta, is not un-
common.
  The cremaster muscles I have seen very much enlarged in cases
of hydrocele of long standing.
  In the increase of involuntary muscles there appear to be no
limits: the power of increasing seems  to be in proportion to  the
necessity, and as they do not tire there is  no end to their power
of acting.
  Whether this increase of the body of a muscle is a new addition
of muscular fibres, or an increase in size of those already formed,
is not easily determined, but I should be inclined to suppose the last.
21. CROONIAN LECTURE ON MUSCULAR MOTION, NO. II.
    [Read before the Royal Society in the year 1797, by John Hunter, F.R.S.]

THE CONSTRUCTION OF  THE ANIMAL   MACHINE  WITH  THE
  MECHANICAL EFFECTS PRODUCED BY THE MUSCLES AS MECHA-
  NICAL POWERS.

        Mechanical arrangement of the Fibres of Muscles.
   The most simple mode of investigating an animal body is first to
consider the matter of which it is composed.  In  this inquiry we
shall find it more than probable that there is but one species of mat-
ter which is peculiar to animals, and therefore I shall call it animal
matter.
   The blood appears to be the most simple modification of this
matter: it is the material from which all the solids are composed.
   The next  modification,  or  what  may  be called  the simplest
organization, is a  certain arrangement of this matter so as to pro-
duce some  action.   This may be  of two  kinds: first,  such an
arrangement as may take  place in  any kind of matter, so as to
produce elasticity.  The second is such as is capable of producing
  * [Hunter has preserved many preparations in his Pathological Series illustra-
tive of this fact, as Nos. 746, 752,755, 758, 759, and 961, &c] 
         CROONIAN LECTURES ON MUSCULAR MOTION.      239

a motion in itself, without the cause being mechanical as  in elasti-
city :  this is the composing of a muscular fibre.
  A muscular fibre is one of the  simplest constructions of an ac-
tive solid, and it is these fibres which compose almost the whole of
many animals.
  The muscles are the powers in  an animal body, and are perhaps
the most  regular parts of the whole.   They are apparently con-
structed of fibres laid nearly parallel to one another ; in some they are
extended longitudinally from  one  end  to  the other of the muscle
which they compose;  in others their direction is oblique to the body
of the muscle; this  obliquity in  some  is  regular from one end of
the muscle to the other, while in other muscles the fibres lie in con-
trary directions.  In some a number of these oblique portions com-
pose  the  muscle;  the parallelism, however, in each portion is
preserved.  This parallelism is only found in some of those muscle
whose fibres all tend to one point of action, and they are nearly of
equal lengths  in every part of such muscles; but where parts of a
muscle produce different effects the fibres vary in length, suited  to
the quantity of motion admitted by the directions of the joints.
  The most simple muscle in an animal body is a bundle of fibres,
distinct from  end  to  end  from all other portions, and having one
determined  use.  The muscles which  move the  globe of the eye
come the nearest to the idea of a distinct muscle;  however, there
are very few muscles in an animal body so unconnected with other
muscles, which makes it  difficult in many cases to say with cer-
tainty what may be called a distinct muscle.
  If we take a view of what we  call  muscles in an animal body,
the human for instance, we shall find that no definition can be given
which will answer to  them all.
  A muscle is said  to  be distinct if it is so at its insertion only,
although it  may  be  connected with  others at its origin, as  the
extensor indicis proprius.  A muscle is  distinct, although connected
with another at its insertion, if there is a difference  in the  use ;  or
although connected at its origin with one  muscle, and at its inser-
tion  with  another; but where two portions of flesh are united at
their insertion, both having the same  use, they are considered as
one muscle.  So that it is the particular effect  which is produced
by a portion or portions of flesh which  in general has made anato-
mists either unite or divide them into separate muscles.
  This, however, has not  been universally followed; for in  some
particular muscles, in which the  origin is of considerable extent,
and  the insertion  but small, each part of the muscle having  the
power of acting separately, and producing different effects  accord-
ing to the parts  which act, (the joint admitting of a variety  of
motions,)  these have generally been considered as one muscle; and
in such muscles, when the whole acts, it produces one  general
effect, as in the pectoralis major  muscle.   Also those muscles in
which the origin and insertion are of considerable  extent, and pro-
duce  different motions of the  same part, yet produce one general 
240          HUNTER ON THE ANIMAL CECONOMY.
effect when the whole acts, are considered as distinct  muscles, as
the trapezius, the broad  muscles  of the  abdomen,  &c.  When a
muscle has a number of insertions, and each portion moves a dis-
tinct joint, while the whole  mass, in the same action, moves all
these joints, it is then considered as only one muscle.  Of this kind
is the longissimus dorsi, the use of which is to erect the whole spine;
but its particular action (if it had any) could only be to move one
or more joints, according to the number of portions in action.

                  External Figure of Muscles.

  Muscles have  various shapes  and sizes;  they  are  long, short,
thick, round,  flat.  They have the fibres either in straight lines or
in curved ones;  they may be broad  and  thin, or hollowed and cir-
cular, making rings; all which varieties of size and shape are con-
nected with their action and use, and have induced anatomists to
give them different names, as teres major, latissimus dorsi, longus
colli, palmaris  brevis,  sphincter  oris,  &c, rhomboides, deltoides,
pyramidalis, &c, &c.
  The form and size of muscles  are adapted to the uses in which
they are  employed ; and  these in  general arise from the nature of
the  parts or joints to be  moved.
  In some muscles the position of the whole leads to the general
direction of all its fibres ; but this does not always happen, being
the case  only in muscles of a more simple construction.  A muscle,
for  example, lies between the os  hyoides and the upper end of the
sternum, which two points lying  nearly in the same plane would
lead one  to presuppose the fibres of such  a muscle to be rectilineal,
which is  really the case.
  The figure of the  muscle often  shows the motion of the joint
which  it  moves,  particularly if it is a simple motion.   This is the
case in the rectilineal muscles and those which are nearly so, or
those which are radiated, as the pectoralis, diaphragm, &c.

                 The different hinds of Muscles.

  Muscles are more or less complex, arising generally from the
different  dispositions of their fibres, which difference is owing to the
manner of their arising  and  being inserted,  more particularly the
former;  and hence we say, muscles are straight, broad, radiated,
half-penniform, complete-penniform,  and  complex.
  The most  simple muscle would be  one whose fibres are in the
direction of its body, or in a straight line between the two resisting
points, and should be called rectilineal; but there is not in the
human  body a muscle truly rectilineal, and from  what has been
observed of the disposition of the  muscles and their tendons, also of
their origins, it is hardly possible  to have one.
   The straight  muscles have fewer fibres in proportion  to their
size than  the oblique, therefore  their powers are less; some are 
         CROONIAN LECTURES ON MUSCULAR MOTION.      241

round, or nearly so ; others  are flat and broad: some of these last
are radiated.
   The half-penniform muscle, although nearly as simple as any in
the body, appears to be the first stage towards combination.  It is
composed  of a series of fibres,  arising from a bone, tendon,  or
fascia, but  more commonly a tendon, of which the  insertion runs
nearly parallel to the origin, representing a quill  with one side of
the feathers taken off.   This disposition of fibres, from the mode of
origin or general  disposition  of the bones  and fascia above de-
scribed, is  almost as common as any in the body.
   The complete-penniform muscle is two  half-penniform muscles
joined together.
   The  complex-muscle is  several  complete-penniform  muscles
united into one.
   There are many half-penniform and complex muscles in the hu-
man body,  but hardly one instance of a distinct complete-penniform
muscle.
   In proportion to their combination their fibres are shorter, and a
greater number in a given size, which must make them proportion-
ally stronger.

                       Situation of Muscles.

   Muscles  which move  bones, cartilages, &c, which are inflexible
in themselves,  generally lie upon them; for instance, the biceps
flexor cubiti lies on the os humeri, the latissimus dorsi upon the back.
Now the humerus and spine have little motion in themselves when
these muscles have occasion to act.   Muscles, however, lie some-
times upon the axis of motion, the body of the muscle going ovei
the joint.  This is most  remarkable in parts near the centre of the
body, as  in the muscles of the spine, and in those of the first joints,
or setting on of the extremities.
   The necessity of this  disposition will appear more evident when
we consider the vast power which  must often be brought  into a
small space.   In the spine, for example, there is not surface sufficient
in this chain of small bones for the origin and insertion of a sufficient
quantity of muscle ; therefore the fixed point of the most superficial
muscles is removed to a distant and broader base, and  they pass
over several joints  to their  different insertions, as the longissimus
dorsi, sacro-lumbalis, &c.
   The same  disposition is necessary in the  first joints of the ex-
tremities ; the extremities  come out at once from  the  trunk, which
is a broad or extended base for muscular attachment, so that the
muscles are obliged to pass over the joint some way to find a sur-
face for their insertion.
   Muscles  in general lie in the  direction of the parts they are to
move; there are, however, exceptions to this  where there is  an
irregularity in the motion of the joint, as in the motions of the head,
shoulders, ribs, thighs, &c.
                              22 
242          HUNTER ON THE ANIMAL CECONOMY.
   In those animals which have one great centre of motion, to which
series of smaller ones are subordinate, as in man, the bodies of the
muscles are in general nearer to the fixed point than to the  moving
one; and the muscular fibres often arise from the fixed point itself,
without the  interposition of a tendon; these muscles, however, do
not come near to the moveable point, but are attached to it by a
tendon, and  frequently a very long one.   This brings the body of
the muscle, which is  the heavy part, nearer to the  centre or basis
of the whole body, which is most able to support it; it also makes
the part to be moved freer, more fit for motion, and better adapted
for other purposes which may be required.

              Tendons and Fascice,  and their Uses.

  In most machines constructed for motion by  art, there is the
machine  itself, or all  the different parts which  are formed for  mo-
tion, so disposed  as to make one part when moved become the cause
of motion in another, communicating it to every part of the machine;
and the moving  power is superadded, and is  not to be  considered
as being  a part of any such machine.  A horse, for instance, cannot
be considered as  a part of any machine which he moves, although
he is essential to  its motion.
  This is also the case in many parts of the more perfect animals
where  great variety of  motion was necessary, parts  being con-
structed for the  purpose of motion only, having no  power  within
themselves, but this power is  superadded or applied to them, as in
the extremities of many animals ; but there is no known animal so
mechanically constructed in all its parts as to have  the  power dis-
tinct from the parts to be acted upon in eveiy part of its structure.
There  are in all animals parts constructed for motion which have
the power of moving within themselves ; those in the more perfect
animals are  the heart, stomach, intestines, &c.   In the more simple
animals all the parts of the body are composed of  materials with
the power of motion, so that in  them the  machine and power are
combined in one, as in the polypus, leech, worm, &c.
   In the parts of the compound animal constructed for motion each
part is independent of another, so that one part may move, or have
its  motion complete, while all  the  other parts are at rest; but
although the mechanical parts are so constructed as to  have their
motions independent, yet the simple effect is not always produced,
for the powers are in many places so applied  as for one power to
move two, three, or more parts, as in the fingers.  The same power
has often a retrograde effect, moving the part which was its fixed
point of motion.
   In an  animal body the  machine constructed  for  motion  is com-
posed of bones, cartilages, &c, and  the unions of these form the
places for motion, called joints.
   The construction of the bones at those parts which constitute the
joints is only such as adapts them for motion  on  each other, not 
         CROONIAN LECTURES ON MUSCULAR MOTION.      243

making them become themselves powers so as to move each other,
as in the machines constructed by art.
  The bones and cartilages are confined or kept together by strong
pliable substances called ligaments.
  There are also parts  called  tendons, which are the medium of
union between the different parts of the machine and the powers.
They have hitherto been considered  as belonging to the powers;
but I shall rather make them a part of the machine itself.
  A tendon is  a peculiar substance, placed between some muscles
or powers and the parts of the machine to be acted upon by such
powers.   It is composed of white fibres placed parallel to each other,
forming a chord, which is extremely flexible, has no sensible elas-
ticity, and is much smaller than the power to  which it is attached.
  Its figure  is in general a  little rounded;  sometimes, however,
rather flattened,  and  in  many situations it is  broad  and thin; in
all cases  it  is  extended between the  body to be  moved and the
power.
  It is sometimes spread out  in breadth, and  is then  called fascia:
this form answers various purposes.   Its fibres in some situations
run pretty parallel, but in general they are  interwoven.  It has
flexibility, strength, and convenience in size.   The application of
this substance  is extremely extensive, complicated, and various.
   The  parts  adapted  to  motion in animal  bodies, as bones, ten-
dons, &c, are  formed with greater nicety, and fitted for more exact
motions in  the more perfect animals, of which we have a striking
instance in the human subject.
  The purposes which this substance, called tendinous, answers in
the animal machine, are the following:
   First, it intervenes between the body to be moved and the power,
to keep up  the exact proportion necessary between them to pro-
duce any determined motions, so that  the length of the bones, or
the distance between the joints or points of motion, the quantity of
motion in the  joint, and the quantity of contraction in the muscle,
are proportioned to one another.   But if this substance had been
wanting, and the muscular fibres had extended the whole distance
between many of those joints, the power of contraction in such a
muscle would  have been much too  great, especially in the ex-
tremities.*  The tendon is used for  this purpose principally where

' * [A most beautiful and forcible example of the use of tendon in limiting the
length of a muscle to the extent of motion required to be produced in the part to
be moved occurs in the sterno-thyroidei of the giraffe.  Had these muscles been
continued fleshy as usual, from their origin, through  the  whole length of the
 neck, to their insertion, it is obvious that a great proportion of the muscular fibres
would have been useless, because  such a condition of the muscle would have
been equal to have drawn down the  larynx and os hyoides more than one third
of the extent of the neck, which is neither required nor permitted by the mechanical
attachments of the parts.  The sterno thyroidei, therefore, proceed from the head
of the sternum, blended together in one fleshy fasciculus for about nine inches, and
in a tendon which is continued for six inches ; this then divides and the muscles
proceed again fleshy for about sixteen inches, when a  second tendon intervenes 
244
HUNTER ON THE  ANIMAL CECONOMY.
 the fibres of the muscle run parallel to the direction of motion; for
 we  shall find  the  tendons to which  many muscles  are attached
 longer than we could suppose necessary, from this reason singly.
 This, however, arises in  them from the  oblique manner in wn^c^
 the muscular fibres are placed, and the mode of their being attached
 to the tendon,  as may be seen in the complete-penniform.
   Secondly, tendons and fascia are in many places substituted for
 bone, there not being a sufficient surface of bone for the attachment
 of all the muscles in an animal body ;  and, by being much smaller
 and  thinner,  they exclude the necessity of bone.
   Thirdly,  tendons  and fascia?, from their  flexibility, answer  in
 many parts better than bone; for  if a long process or thin lamella
 of bone  had  united the ends of the muscles to the principal bones
 to be moved, no motion could have been produced by the endeavour
 of such  muscles.   In many situations, where  flexibility  is not re-
 quired, they answer better than bone, from their yielding to external
 or internal pressure, which bone could not have done without being
 liable to  be broken; as in those situations where they gi.ve attach-
 ment to  two muscles, and where they cover  many muscles, as in
 the forearm.   The  advantage arising  from the flexibility of  tendon
 and fascia is seen in its full extent by comparing the muscles of
 the more perfect animals with those of the oyster, lobster, or turtle,
 where many of them are attached to  external  shells,  instead of
 fascias.   Flexibility  also  allows them to vary their  direction, by
 which means they vary the motion of the parts, as  in the tendon
 of the biceps flexor of the forearm winding round the head  of the
 radius: the first action of the muscle (in some positions of the bone)
gives it  rotation  upon its axis, the  second bends it  upon  the os
humeri.   Similar actions are produced by the latissimus dorsi and
 teres major.
  Fourthly, fascias  from their strength answer in many situations
better than bone, for a lamella of bone  of the same thickness would
in many  cases  have been  broken by the contraction of the muscle
 to which it was attached.
  Fifthly', it was necessary that some substance should be introduced
 as a  medium between bones and muscles, to admit of  the nicety  of
 action and freedom of motion we find in many parts of the body,
 particularly in the fingers; which could not have taken place if the
 muscles  had been continued from bone to bone.
  Where flexibility is not necessary, we find then  that there is a
 continuation of bone, as  in many birds, as in the leg of the turkey,

 in each between the preceding and the next fleshy portion, which is finally in-
 serted into the thyroid cartilage, and, by a continued fascia, into the os hyoides ;
 thus the quantity of contractile fibre is proportioned to the required extent of
 motion by  intervening tendons; the sterno-hyoidei being wanting, or their place
 supplied by the sterno-thyroidci, as in some other ruminants.
  The analogue of the omo-hyoideus is, in the same animal, adjusted to its office
 by a  different and more simple modification ; its origin  is removed from the
 shoulder-blade  to the nearest point (the third cervical vertebra) from which it
 could act with the requisite force and extent upon the os hyoides.1 
CROONIAN LECTURES ON MUSCULAR MOTION.      245
  partridge, &c, and through the whole body of most fishes; so that
  tendon is to be considered as a substitute for bone where that sub-
  stance would be improper.  Physiologists, however, have given a
  very different idea of it, supposing it to be a continuation and con-
  densation  of the muscular fibres; for which supposition  there is
  no proof, even the smallest shadow of reason, either from  analogy
  or from the parts themselves: it is therefore too absurd to deserve
  refutation.
    Besides the uses of fasciae above described, we find them in many
  parts of the body covering muscles,  giving origin to them, binding
  down  the  belly of the muscle, and  also binding  down the tendon
  which is attached to it: this application of them is chiefly  found in
  the extremities, particularly the forearm and leg.
    Where the fascia binds down the tendon at or near the joint it is
  called  < annular ligament,' which is in general little more than the
  fascia  made strong;  but where greater nicety in the motion of the
  parts is required we find annular bindings independent  of the gen-
  eral fascia, as in the fingers and toes.   These are to keep the ten-
  dons from  having lateral motions, and where the joint makes an
  angle,  to prevent their  coming  into straight lines, which would
  happen if not prevented by this annular ligament, and which would
  destroy the intention of the joint, as is evident in the fingers.
    Where the fascia covers two muscles  it is fixed to  the tendon
 which lies between them, and generally covers their tendons.
   Where it covers a tendon it almost surrounds it, making a  kind
 of theca, and is fixed to the bone along which the tendon passes.
   These circumstances only take place where muscles  are placed
 at a considerable  distance from the  parts to  be moved, and their
 tendons pass over more joints than one,  as  in  the  muscles of the
 forearm and leg, where the tendons go to the fingers and toes.
   Fascia is sometimes very thin, called membrana  communis mus-
 culorum, covering superficial muscles, particularly the broad ones,
 as the obliqui externi, latissimus dorsi, pectoralis, &c, and on some
 of the deeper-seated broad muscles, but thinner  and looser  in its
 connexion with the muscles.   It is never met with  in this state on
 the round muscles.
   It would  seem to be intended to connect the skin by its cellular
 membrane more closely to the muscles, by which means the  skin
 may be in some measure moved by them.
   The fascias in some instances give insertion to muscles,, as in the
 thigh, and to the broad abdominal muscles.

               Attachment of Muscles to  Tendons.

   As the body of a muscle is much  thicker  than the  tendon to
which it is attached, the fibres of the one cannot be continued to the
other in a straight line; therefore the end of the tendon is not joined
to that  of the  muscle in one line, but  by a tapering point  or an
irregular edge, to gain surface for the  insertion of the  muscular
                              22* 
246          HUNTER ON THE ANIMAL CECONOMY.
fibres, the oblique ending of a small body being capable of becoming
equal to the less oblique ending of a thick one; but the direction
of the tendon cannot be the same with the muscular fibres, but must
be more or less oblique, so that an angle  must be formed  at their
union, the muscular fibres being bent a little in towards the tendinous
ones.   This obliquity  in  the  direction of  most of the muscular
fibres, and of their attachments at both ends when they have tendons
at both origin  and insertion, makes the  muscle become gradually
thicker from the body of the first tendon to  the most distant point
of that tendon; and if the middle part  of the muscle  is free from
tendon, that part will be everywhere equal in size, or if the tendon
at its insertion goes  higher than  at its origin, the part  where these
tendons are opposite and parallel to one another will also be equal
in size, the  body of the muscle from that  part becoming gradually
smaller upwards towards its origin, and  downwards  towards its
insertion.
  From such disposition of fibres the bodies  of most  muscles  are
much longer than their  component fibres, which  produces  in  the
same proportion a  shorter complete  tendon.   This circumstance
lessens the thickness  of the  bodies of such  muscles, and  also of
their  extremities, which gives to  the  muscle a curve  in its outer
line.
  The obliquity in the direction of the muscular fibres admits of
there being a greater number, and lengthens the swell  in  the time
of contraction, by which  means  the motion of the muscles in the
cellular membrane becomes more free, the swell is smaller, and the
smoothness of the  whole body is preserved.  The tendon at  its
origin  is generally on one side, or surrounding the  muscle, and the
inserting tendon is on the  opposite side,  or next the centre of
motion.


                Origin  and Insertion of Muscles.

   In describing the origin and insertion of muscles the tendons are
always included, and  this is very necessary to be understood of the
insertion, as it is the point of insertion  which in some  degree gives
the use of  the muscle.
   The origin  of a muscle is in general  the most fixed point,  and the
insertion the point where the greatest motion is produced ; in differ-
ent muscles, however, these points are subject to variations, and on
different occasions  in the same  muscle, most of them being capable
of acting from either  end.  Some of these variations may be consi-
dered as natural, and others as a force upon Nature.
   I shall call the variations natural where the effect is necessary in
 the natural movements of any part of  the body, such  as the exten-
 sors of the thigh, the glutaei, particularly  the gluteus major, are
 commonly understood to produce; for these muscles,  in the action
 of walking, when the leg is brought forwards or bent by the flexors,
 extend the body upon the thigh, by which action the body is brought 
         CROONIAN LECTURES ON MUSCULAR MOTION.      247

forwards before and over the foot;  also,  after stooping or bending
the body forwards, the glutceus muscle raises it; and these are as
much the actions of this muscle as bringing the leg and thigh back
upon the body.
   Some muscles are capable of performing similar inverted actions,
although not commonly so  employed as the recti abdominis, whose
ordinary use is to bend the body upon the pelvis, but which some-
times, however, bend the pelvis upon the body.  Those which I call
a force upon the natural  effect of the muscle, or an inversion of the
fixed point, are where the moving point is by art, or something foreign
to the body made the fixed  one, as the hand ; and the action of the
muscles, instead of bringing the hand to  the body,  draws the body
to the hand.
   In many animals, however, the effects  of certain muscles are re-
ciprocal, and these, therefore, cannot be  said to have an origin and
insertion, both the parts to  which they are attached being equally
moveable in themselves,  and there being no power capable of keep-
ing either the one or the other firm, as is very evident in animals
where the two points of attachment, or parts to be moved, are similar
or in pairs, as in the bivalve  shell, where the motion in the two valves
is equal.
   The origins of muscles are in general  more simple than their in-
sertions, nothing being wanted but a sufficient surface for attach-
ment, which is generally required to be  pretty extensive ; and for
this purpose there are  various contrivances,  which have given rise
to particular names, for the various.kinds of origins.
   The origin of a muscle  is generally from  an immoveable part
with respect to the action of that muscle, and commonly from the
most firm or solid parts of the body, as bones, cartilages, periosteum,
tendons, and fascia; some  muscles, however, arise  from soft parts,
as the lingualis, orbicularis oris, &c.
   The insertions of muscles are less simple, for as the insertion is
to produce the various motions of the  parts, and, as the construc-
tion for motion is hardly the same in any two joints,  more nicety
and art is required; the  insertions of muscles are commonly more
determined than the origins.
   Few muscles are so situated as to arise from surfaces  at  right
angles to the direction of their fibres, as they generally pass nearly
in the same direction with the surface from which they arise, whe-
ther bone,  tendon, or  fascia.  They,  therefore, take  their origin
from a part as they pass along  it, which renders  it very oblique,
 and produces  the form of muscle called half-penniform.  Some
 muscles, however, both arise from, and  are inserted into, surfaces
 at right angles to the  direction of their fibres, as many of the
spine, &c.
   The insertions of muscles are more general than their origins,
 for they must be inserted into every part of the body to be moved,
 and therefore we find them inserted into bones, cartilages, periosteum,
 tendons, fascia, and many of them into soft parts, as  the skin, cel-
lular membrane, the tongue, &c. 
248          HUNTER ON THE ANIMAL CECONOMY.
   In describing muscles, they are never said to be inserted into, or
 to arise from, periosteum, but from the bone the periosteum covers,
 as it is upon the bone the effect is produced.
   Muscles never arise from, or are inserted into, capsular ligaments,
 for although in some few cases they seem  to  run into, or are at-
 tached to them, the effect is not immediately on the capsular liga-
 ment,  but on the bone beyond it, and the ligament is strengthened
 at this part in proportion  to  the  power of the muscle; so that in
 this  case, as far as regards the mechanical effect, the ligament and
 tendon may be considered as Qne.
  Many tendons,  in their course over joints, adhere to the  liga-
 ments, and bring them along with them in the action of their muscles.
 This adhesion, however, is only to  bring out a secondary use, to
 save the ligament  from being  bruised between the  bones,  which
 otherwise might have been the case.
  Many muscles besides these insertions give off fibres to the fasciae,
 which cover other muscles,  as is evident from the lower edge of the
 pectoralis major, biceps flexor cubiti, semitendinosus, &c, but what
 is intended by it is difficult to determine.
  The origins of muscles are generally further from  the centre  of
 motion of the part to be moved than the insertion; remarkable in-
 stances of this are seen  in the biceps flexor and triceps extensor of
 the forearm, and all  the movers of the  hand and  fingers.  This
 gives neatness to the parts to be moved ; but its principal use  is to
 give velocity to the motion,  with a small quantity of contraction;
 what it gains, however, in velocity, it loses in strength.   That
 velocity is the intention  is evident, for  if the muscular fibres had
 been continued to the most distant end  of the  bone to  be moved,
the muscle must have been longer, and must have contracted more,
to produce the same effect, which contraction must  have taken a
 greater length of time.*
  Many muscles  arise near to the centre of motion  of the part  to
be moved, and are inserted at a considerable distance, as the del-
toides.   This also produces a great deal of motion in the part to be
 moved, with very little  contraction of the  muscle;  for when the
greatest quantity of motion is produced, the insertion has approached
 very little nearer the origin.
  This  kind of insertion gives an advantage to the power of the
 muscle, which the other has  not, viz., a  much longer  lever,  and
 allows the muscles to communicate their strength to the moving
 parts more fully, although with less velocity; and being employed
 upon parts of considerable  extent, as the arm and leg, and gener-
 ally  upon the first joints  of them, the effects upon the hand and foot
 are very considerable.
  In the formation of many parts of the body neatness is a prin-
 cipal object, as is visible, not only in the external form of the limb
 but in the parts constructed for motion; as in the formation of the
  * [The extent of the space through which the bone is moved  is also greatly
 increased by this arrangement, in comparison with the extent to which the muscle
 itself contracts.] 
          CROONIAN LECTURES ON MUSCULAR MOTION.      249

bones, and their situation with respect to one another, and the mode
of removing the  inserted  tendon (when too close to the centre of
motion to produce a sufficient effect) a little further off, by means
of little moveable bones called patellee or sesamoid bones, as in the
knee, first joints of the thumb, and great toe : and where this  con-
struction  would be clumsy and  inconvenient, as in the fingers and
lesser toes, the two  tendons  which are obliged to pass along these
parts to their insertions at the second and  third joints, are so dis-
posed in their course, that the profundus, or one nearest to the bone,
acts as a patella to the  other, keeping  it  at a distance  from the
centre of motion equal to its own thickness;  and the  sublimis or
upper one is obliged to split into two near  its  termination before it
can be inserted into the  second bone.   The advantage gained by
this- construction is, that  the tendon of the  muscle employed in the
greatest action is removed  further  from  the centre of motion  than
it otherwise could be, and from which the  other sustains no disad-
vantage.
                 Adaptation of Muscles to Joints.

   It is to be understood that the joints of an animal are  fitted for
motion, and that their form, with the application  of the muscle or
power, are, in a natural  state, so adapted  to  each other that the
power acts with  the greatest advantage, and that any variation
from the natural form or position of the joint weakens the effect of
the power.  This  may be demonstrated in those who turn out their
toes, as in a dancing-master, who, before  he makes a leap, turns
his toes forwards.
  Few joints in an animal body are confined to one motion, there-
fore either a number of single muscles must  be employed, or the
direction of the muscular fibres, of the tendons, and of the inser-
tions, must be  so  disposed  that a few  muscles may produce the
different effects.
  Joints admitting of motion in only one direction come nearest to
a simple joint:  the joint of the elbow is perhaps as near this as any
in most  animals,  as  also the joint of the lower jaw in the  car-
niverous animals, and the fingers in most animals:* the muscles of
such joints are tolerably simple  in their structure, direction, and
insertion.
  In the joints  which admit  of various or  compound  motions, the
construction of the muscle, the course of its different fibres, the dis-
position of the  tendon in its course and insertion, produce a great
variety of effects.
  This, indeed, was absolutely necessary in a number  of animals,
more especially those which have extremities, and particularly the
human subject, in  which  there are  more  motions  produced  than
separate muscles to perform them; nor was it possible, in the pre-
sent construction of bones, &c, to have  placed particular muscles
  * [In insects and  Crustacea every joint of the extremities, save that which
is between the limb and the body, is ginglymoid, and limited to motion in one
plane.] 
250          HUNTER ON THE ANIMAL CECONOMY.
 so as to perform all the motions, without interfering in the qpposite
 actions.  In the human subject the number of muscles exceeds that
 of any  other animal; the motions in the joints, however, are still
 greater than  can be accounted for by the increase  in number ot
 muscles, the difference in the construction  of the muscles, as well
 as of the joints, producing this difference, which is so remarkable
 in  the joint of the shoulder, the rotatory motion  in the  forearm, and
 the joint of the thigh.
   Instances of the  different, motions  produced by  the shape  of
 muscles, their mode of application, and the disposal of tendons, are
 seen in the biceps flexor cubiti, latissimus dorsi, &c, passing some
 way round the bones into which they are inserted, so as to produce
 two very  different  motions  in the  parts; at one time they may
 move the  part through some space, at another time  upon its own
 axis.   The muscles in the lower jaw in  graminivorous animals
 give a remarkable instance of this, there  being  hardly any of them
 which do not perform more than one motion.
   The disposition of tendons will often give a different direction to
 the body moved from that of the  muscle,  arising from the tendon
 bending over some  fixed point and taking another direction, which
 is beautifully illustrated in the  trochlearis  muscle of the eye, the
 body of it passing  in the same direction as the straight muscle of
 the eyeball, while from the course  of its tendon it counteracts the
 oblique, which passes  in  a  different  direction.  The  obturator
 internus of the  thigh and circumflexus palati are both  of this kind.
   The different positions  of tendons shall make two  muscles pro-
 duce the same effect in different ways, being inserted in the opposite
 sides of the same joint.  The gastrocnemius,  which is inserted into
 the heel behind the joint  of the foot, pulls  the  heel up, which de-
 presses the toes.  The tibialis posticus and peronei muscles, which
 pass in the same direction, and are inserted before the joint of the
 foot by  means of their tendon passing round the joint, also pull the
 toes down, which raises the heel.
  Muscles, by the course and mode of insertion of their tendons,
 shall perform very differently a series of  regular motions, bending
 some jointsand extending  others.   Such are the uses of the lumbri-
cales  and  interossei interni  upon the fingers and toes: for  their
course is before the centre of motion  in the  first joint,  but by wind-
ing round the second bone they get  upon the back of the fingers
and extend the two  last joints.  These,  by their  situation and inser-
tion, produce an effect which could not be performed  bv the other
 flexors or extensors of the same parts.
  From the various formations of joints, and the different positions
 and insertions of the muscles or powers,  the  greatest  force of the
power is required at different periods of the motion.
  In all those where the  power is between the  centre of motion and
the resistance,  the greatest action of the  muscle is required at the
beginning, as a  smaller contraction of the muscle produces a greater
effect at this time than afterwards,  as in the deltoid.
  Where the power and weight are at the two ends and the fulcrum 
          CROONIAN LECTURES ON MUSCULAR MOTION.      251

 in the middle, as  in the biceps extensor of the arm, or where the
 power and the fulcrum  are at the two ends and the weight in the
 middle, as in the muscles of the tendo Achillis,  the greatest force is
 required in the last  part of the motion.
    Where there is no lever, but one body moving round a centre as
 a pulley, which is the case in the  extensors of" the knee-joint, the
 same force is required through the whole of the motion.
    We  may observe that the ligaments of the joints are necessarily
 so constructed and placed with respect to their motion as to produce
 an effect analogous  to  that of a centre-pin in a plain circular joint,
 in  all the various situations of the centre of motion.
   There are few levers of the first kind in the body, on account of
 the unevenness in the  effects  of muscular  contraction upon them,
 arising from the variation taking place in the angle of insertion of
 the muscle; they  are  therefore introduced where that is compen-
 sated by some other  circumstance in the action.
   The  motion of the body upon the thigh is  a lever of this kind, and
 is generally used in raising the body; but as the body becomes
 more and more bent it requires less power  to overcome  the power
 of gravity in the body, therefore the  angle of insertion is becoming
 more and more in the same plane with the moving part.  The same
 thing takes place in  moving the heel.
   The  angle of insertion can only have its effects vary when the
 insertion  is some  way from the centre of  motion, and this  only
 when in levers.
   When in levers  of the first  kind (which extend joints) the effect
 is gradually becoming  less; as, for  instance, the extensors of the
 forearm, which are inserted into the olecranon, because the angle
 is becoming less and  less; but perhaps the velocity  which the parts
 may  commonly acquire  make up this  loss.   When inserted into
 levers of the second kind  they are gaining in their effect, the angle
 becoming greater,  as in the flexors of the forearm.
   In  the lever of the first kind the quantity of effect, according to
 the quantity of contraction, is becoming more and more as the angle
 becomes less.   In  the  second  it is  becoming less  and less as the
 angle becomes greater.

            Muscles going over more Joints than one.
  Many muscles, or  their tendons, go  over two joints while they
 only move one, and the  joint which they do not   move is often
 moving in a contrary direction, from the action of another muscle;
 this happens in the biceps flexor and extensor of the forearm, the
 flexors of the leg, &c.  This disposition saves a great deal of mus-
 cular contraction;  for by the biceps going over two joints while it
is employed  in bending  the forearm upon the arm, the arm is bend-
ing back upon the scapula, which last action would produce in some
 degree a flexion of the forearm, even if the  biceps flexor did not
 contract at  all, but only  remained without relaxing.  This arises
from the motion of these joints going  zigzag to one another.
  Muscles whose tendons pass over two joints keep the joint not to 
252          HUNTER ON THE ANIMAL CECONOMY.
be moved, firm; which is  of  great service, as when we bend the
forearm by the biceps flexor, the two heads rising from the scapula,
especially the long head which runs through  the joint, keeps the
joint of the shoulder firm.   In  this motion there are muscles acting
on both sides of the joint.   Had it not been for this purpose, the
biceps flexor might  as well have  arisen from the head of the os
humeri.
  Muscles often go over two,  three, or four  joints, and only move
the third and fourth,  as the  flexors of the  last joints of the fingers ;
but to prevent the first and second joints being moved by this action,
the extensors of the intermediate joints are obliged to interfere and
keep them from bending.
  Every joint has a certain quantity of motion, and the quantity of
contraction of the muscles of that joint are adapted to that motion:
we have  therefore in joints of considerable motion long muscles, as
those of  the knee,  and in joints with little  motion we have short
muscles,  as those of the spine.

           Of the Strength of the Body as compounded.
  The strength of a part and  the strength of the whole body is in
proportion to the natural resistance, which arises either from some
body to be propelled, as the blood, urine,  &c,  or from the position
of our bodies,  to  overcome gravitation; for  every muscle in the
body is just  able to move the part to which it  is fixed with tolera-
ble ease in the most difficult position, and any  additional weight in
that  position will fatigue it, it  being unable to support it any time.
From this it would appear that the different parts of our bodies are
not much stronger than can support their own motions with ease;
and whatever motion the body can perform with ease, by exerting
itself it can give it a considerable velocity, or support  a greater
weight for a continuance.
  If our muscles are capable of moving our bodies in every position,
they must be able to move much more in some positions than others.
If I can raise my body from the  ground perpendicularly up when
my feet are fixed  upon the ground and my  knees  bent  at right
angles, I can support or raise a much greater weight when upright
or nearly so.
  If a horse raise himself from the ground when his legs are bent,
he can support a greater weight when erect or standing; and if
loaded with no  more than  he  can stand  under upon three feet, he
can walk with it.  A leg also that can raise  the quarter of a horse
from the ground can move  the parts of which it is constructed only
with great velocity.
   If you load a man with  no  more than  he can stand under upon
one  foot, he can walk with the load.   A man can raise his whole
body upon his hands, and therefore can move his hands with great
velocity when they are put  into motion without the body.

   The Efects arising from the  different Constructions of Muscles.
   The straight narrow muscle, whose fibres  run parallel, generally 
         CROONIAN LECTURES ON MUSCULAR MOTION.      253

employs all its fibres, so that when it acts, the whole muscle is  in
action at the same time.
  The broad and radiated muscles do not always employ the whole
of their fibres at the same time, each  part often acting separately,
like  separate muscles ; they are capable of taking on an  action at
any  one part,  and  of continuing  from that part a succession  of
actions to any other part, or through the whole muscle;  and they
are capable, by an  action of the whole muscle, of producing one
general effect.  The action  of the lateral portions of such  muscles
affects the tendon  somewhat similar  to the complete-penniform;
therefore the middle fibres  must either be longer than the  lateral,
or have  a  great  power  of  contraction, which will  be better un-
derstoood after the explanation of the action of the complete-penni-
form.
  The temporal muscle is an exception to the ru-le of muscles being
made radiated  to produce  a succession of actions;  for whatever
part  of this muscle  acts,  nearly the same effect is produced ;  such
muscles, cceteris paribus, produce effects proportioned to their length
of fibres.
  These muscles have one  advantage, which is, that  their fibres
are  much longer than  those of  any.other muscle whose body is of
an equal length; they can therefore contract much more, and are
always used in  the more  extensive motions.
  The half-penniform muscle is, I believe, similar in its action to the
foregoing;  for although the  fibres  are more oblique, the tendon is
moveable laterally, so  as to  move nearly in the same line with the
fibres.   This kind of muscle is  never used in extensive motions,
except where there is considerable distance between the origin and
insertion, to admit of sufficient length of fibres.
  Although there is hardly an instance of
a complete-penniform muscle in the body, a                   B
yet as all the complex penniform act  upon
the same principle, I shall explain the ef-
fects in a supposed  complete-penniform,
and  show that  this  disposition of fibres
produces a greater effect than any of the
foregoing.
  In the action  of these muscles we sup-
pose that the inserted  tendon is always
moved in the middle line, between the two
origins of the muscle,  and  therefore the
muscular fibres in this action do not lose
their obliquity, as in the half-penniform,
but have it increased, which produces  a
greater effect.
  Let A C and B C  represent two  fibres
of a penniform  muscle in their extended
state, A and B  being their origin, and C
the point of insertion into the tendon C D.
 
254          HUNTER ON THE ANIMAL CECONOMY.
   Suppose these fibres contracted to the points E and F, it is evident
that such contraction will bring the point of insertion from C to G,
and that the motion of the tendon will be to the contraction of the
muscle  as  C G is to C F or C E ; for A G is equal to A E, and B
G equal to  B F, or A and B are the centres of the circles AGE
and B G F.
   The advantage arising form this construction of muscle  is great,
as it allows of a great number of fibres in small bulk, and  is  there-
fore used where strength is  required.  It  is  also used  where the
quantity of motion required is greater than the distance  between
the origin and  insertion would admit of in any other construction
of muscle.
 22. CROONIAN LECTURE ON MUSCULAR MOTION, No. III.

     [Read before the Royal Society in the year 1779, by John Hunter, F.R.S.]

                    Of the Effects of Muscles.

   In the spring of 1776 I had the honour of delivering to this Soeiety
 the Croonian Lecture upon the self-moving power in animals seated
 in the  muscles, in which I also made some observations on  the
 analogy  between this power in animals and a similar  power  in
 vegetables.
   I was  then desired to prosecute  this subject, and accordingly, in
 the winter following, I presented a paper, in which I considered  the
 most remarkable circumstances relative to this power in animals,
 through which they are  enabled to perform all their various mo-
 tions,—such as the arrangement of the fibres in the construction of
 all the muscles; the distinct muscles, their figure, kinds, and situation ;
 the tendons, and fasciae, with their uses; the applications of muscles
 to tendons, their origin and insertion, and the fitness of them to  the
joints.  It was here noticed  that their effect in some cases is equal
 to their quantity of contraction ; in others not.  The different quan-
tity of contraction in the same  length of fibres in different muscles
 was observed, and the effect arising from the different construction
 of muscles.
   As the muscles are, by their contraction, the cause,  either im-
 mediate or remote, of every action in the animal, and as animals
 are so  constructed as to produce evident mechanical  effects, arising
 from an application or combination of the mechanical powers (the
 contraction of the muscles being the  power or original cause), I
 shall now consider this mechanical application and its effects, wi'th
 which  I  shall  slightly  compare the  applications  and  effects  of
 the mechanical powers as applied  in  machines which are the pro-
 ductions  of art.
   Muscles are the first simple  powers in  an animal, by which all 
         CROONIAN LECTURES ON MUSCULAR MOTION.      255

the mechanical effects are ultimately produced ; but an animal body
is very differently  constructed from that of a machine.
   A machine is composed of a series of parts, having a  regular de-
pendence on each  other; and the power which produces motion is
applied only at one  end of these  parts, although  two, three, or
more effects may  ultimately be  produced, which effects, notwith-
standing, must  therefore arise from the  multiplication  of the parts
of the machine, and not from  the increased number of powers.
   But an animal is composed of parts, each part, and each motion
of each part, having its own moving power, capable of producing
its immediate and remote  effects independent of each other; so
that in animals many effects may be going on at one and the same
time, and each  actuated  by its own peculiar power, by which
means an innumerable variety of effects are carried on at the same
time, and without the least confusion or interference with each
other.
   A muscle, as to  itself, may be  considered in  two lights, one re-
specting its  quantity of contraction, and the other its power, both
of which  produce  considerable  effects in the  body, and  each is
employed according to circumstances.
   Every muscle in an animal body may be considered  as a simple
independent power;  and if we  attend to the  effects  that many
animals  are capable of producing, particularly the  motion of
fishes and the flight of birds, we  shall  see great reason to admire
the immense velocity and  great force with  which their  muscles
are contracted; and  if we  compare  the  effects produced by the
contraction  of  their  muscles  with the weight  of each muscle
and the part which is to move,  it  may lead us to conclude  that
there probably is  not in  nature  a more  active  simple power
than the contraction of the animal muscles.  An animal is  per-
haps  the only machine that has the  power of overcoming its
own gravity.
   In considering animal bodies in  general in a mechanical  light,
we should first attend to  the  most simple mode of action in the
animal, or the mode of action of the muscles in the most simple
animal, and  proceed from the most simple to the most compound
or complicated, in  which latter may be discovered applications and
combinations of the several  mechanical powers  (which for  beauty,
simplicity, regularity,  and aptness far excel all human applications),
in order to produce the manifold  effects of animal motion, and to
accommodate the ultimate velocity or force at the same  time to the
particular effects to be produced, as well  as to the simple power of
contraction  in the several  muscles which act  as first  movers in
producing that effect.
   In many animals the parts endowed with the first principles of
motion, viz., the  muscular fibres, are themselves formed in  various
shapes, so as to constitute  complete  animals of the most simple
fibres; and  even in the most complicated animal  many  distinct
parts  are composed  of those  moving powers, forming  regular 
256          HUNTER ON THE  ANIMAL CECONOMY.
bodies, called organs, commonly producing  of themselves a vast
variety of effects, by which means many of the numberless internal
actions respecting the  animal ceconomy are carried  on; so that
even in those more complicated animals we have the first organiza-
tion formed of muscular fibres alone, in the same manner  as in the
more simple animals.*
   This would lead us to consider the effects of muscular contraction
in very different views, viz., according to the various effects they
are capable of producing in animals of all the various constructions
and complications.
   In many of the more simple animals there is  little  else besides
those formations or organizations composed of muscles.  A polypus
is little more than a  muscular  bag, and  by the  contraction of its
fibres in different parts, and in different directions at different times,
the bag is changed into various forms and sizes.
   A worm seems a little more complicated: however it is in reality
little more than a body formed of different parts, each of  which is
composed of muscle.   A slug, a maggot,  as also numberless tribes
of sea-animals, come under the same description.
   But  as animals emerge from this simplicity of construction, be-
coming more  and more  complicated,  having  particular parts
added, and those parts being composed of something besides mus-
cle, and it also being necessary that these should move, and be so
constructed as to direct, circumscribe, increase, or limit the motion,
we find the muscular fibres of such animals collected into various
portions and forms, in order to give all the different motions to these
superadded parts which were  taken notice of in the former lecture.
Those  additional parts  are composed  of more  rigid  matter than
muscle, viz.,  bones, cartilages, &c, on which the muscles  can have
no  other  influence than  by  giving them motion.  There are a
number of  those bones, cartilages, &c, in  many animals, some
having more, some fewer;  and  they are  connected in  such a
way as to form between them intervals fit for motion,called joints:
in most parts of the body there is a series of those bones and joints,
as the spine,  the extremities, &c.
   Many of these bones are so  formed, and so placed and connected
with one another, as to form  levers (and  those of  all the various
kinds), which direct and limit  the motions, so as to produce a regu-
larity in the whole.
   As the relative inclinations and positions of those several  bones
which  are immediately  connected and  joined  together  are very
various, it follows that there must be a variety in the angle  of  in-

  * [Hunter here compares the first-formed  parts of the vertebrate embryo,
derived  from the mutually receding layers of the germinal membrane and  the
folding of those layers, with the simple homogeneous tissue of the hydra or other
acrite animal.  And, as he applies the term muscular to the contractile tissue of
these animals, so he would also regard the homogeneous  gelatinous parietes of
the newly formed digestive ?ac of the embryo of the higher organized species as
being in like manner endowed with contractility, and therefore ' formed of mus-
cular fibres,' or contractile substance 'alone.' 
          CROONIAN LECTURES ON MUSCULAR MOTION.      257

sertion of the several muscles, to accommodate them to the particular
circumstance of each joint.   And as those inclinations vary in the
motions of the joint, so must the angle of insertion of the muscles
which will produce a difference in the effects, both  in  the  power
and quantity of contraction.
   To this great variety of these levers and joints we have the mus-
cles adapted.
   We may observe, that the more perfect the animal is, the more
curiously these levers and joints are  formed, the joints  commonly
consisting of compound curves (which is the most remarkable in
the  more perfect  animals), by  which means their  own motions
admit of greater variety.
   The human subject is a striking instance of this, having the joints
more compounded, and the  motions less  limited, than in any other
animal that I know, which circumstances require a greater variety
of muscle, and the greater nicety in the  adapting of each  muscle
to produce its peculiar motion.
   In the most perfect animals there are very few joints whose mo-
tion is simple, or which  are confined on all occasions  to move in
one direction ;  for whatever may be their chief or ordinary motion,
in many there is some other motion compounded with it; nor are
there many joints  which move upon one  centre in all their motions,
but they shift their centre as the curve varies.*
   These firm inflexible substances are kept together by soft, yield-
ing yet sufficiently strong parts, called ligaments, which are neces-
sarily so constructed and placed, with respect to the  motion of the
joint, as to produce an effect analogous  to that of a  centre pin in
a plain circular joint, and in all the various situations of the centres
of motion.
   I  may  be allowed to observe,  previous  to entering upon  th
mechanical  motions  produced by the  muscles in an  animal body,
that, without external resistance, there would be no such thing as
progressive  motion in an animal;  for although a  muscle has  the
power of contraction in itself, and is capable of moving all its differ-
ent parts  upon  itself, yet it  cannot move any other part without
having some fixed  point to act from, which is the  greatest point of
resistance.  There is in every animal, therefore, a fixed point from
which the parts of the body  take  their principal  motions.  In the
human body this fixed point seems to  be  in the joints  of  the  thigh-
bones; which point, being in the middle of the body, must be com-
mon to the extremities.   We see,  therefore,  that the body  either
moves on  the  legs, or that the legs  move  on the  body or trunk.
Besides this, there  are many fixed  points, so that the  body is to be
looked upon as a chain of joints whose general centre of motion is
in  the joints of the thighs; but each  has its  fulcrum, or centre of
motion, which is always on that side next to the first, or the general

  * A remarkable instance of this we have in the joint of the lower jaw in grami-
nivorous animals.
                              23* 
258          HUNTER ON THE ANIMAL CECONOMY.
centre of motion of the whole, by which means  the  smaller moves
upon the greater, the  toe upon  the  foot, the foot upon the leg, the
leg upon the thigh, and the thigh upon the body.  The same in the
arms, the wings of birds, the tails of fishes, the oars of a boat, &c.
But those motions can be, and  often  are,  inverted, so that the
greater  can be  made  to move upon the smaller; as, for instance,
the body upon the thigh, the  thigh  upon the leg;  or, in birds, the
body upon the wing, &c.; but then  the smaller  must be so circum-
stanced  as to be the fixed point,  which cannot be without external
resistance.   It  is the  inverted  motions, then, which produce the
progressive;  but it is  necessary, for the  production of a succession
of them, to  bring in also the motion  of smaller parts upon greater;
the two kinds of motion are, therefore, acting alternately whenever
the progressive motion is continued  beyond the  first action.
   The animals  which move upon the earth have it for their point
of resistance.   Birds  are supported  and  propelled in their flight by
the resistance of the air ;  and fishes,  like  boats, by the resistance  of
the water.
   The effects of muscular contraction  may be divided into three
kinds.
   The first is, where  the effects are  in those parts of the body which
are principally composed of muscle : these simply  vary their con-
figuration without extending their power beyond themselves, as  in
the actions of many of the more imperfect tribes of animals, as the
leech, polypus,  &c, and in many parts of the more perfect animals,
as the heart, stomach, intestines,  bladder,  and  all  the vascular
system.*
   The  second  is where the  effect  is more extended and reaches
beyond  the muscles themselves to such  adjoining parts as are either
formed  simply  for motion, as bones, cartilages, &c, or whole parts
of the body, such as an eye, a lip, the skin,  &c.
   The third is  where the effects are mixed,  viz., partake of both the
preceding,  as in those produced by the muscles of the tongue, of
respiration, of the abdomen, &c, where they both  move parts and
alter  their configuration.
   The  first and third  kind of effects of muscles, when considered
in the more perfect animals, are more connected with the  internal
ceconomy of the animal  than  with the  mechanical  application of
the power of muscular contraction; therefore in  them it  is  the
second  which comes  properly under consideration, as mechanical,
since it produces visible mechanical effects  upon parts formed  for
motion, and evidently calculated to vary the velocity from that of
the first.     •                        j            j
   The  application of muscles  in an  animal body is either to pro-
 duce a quantity of motion equal to the quantity of contraction of
the muscle; or, by  the application  of levers, to  give  a greater
   * [This is not  exactly true of these viscera,  for their contents ejected by the
 contraction of the surrounding fibres act upon the parts into which they are  pro-
 pelled, as the bone moved by the muscle inserted into it also carries the  part
 connected with it along with it in its motions.] 
         CROONIAN LECTURES ON MUSCULAR MOTION.      259

motion  than  could  be produced  by the simple contraction of the
muscle.  This in general is not the case in machines composed by
art;  for in  art  the  principal reason for the introduction of me-
chanics is to acquire power  in  the effect, which  obliges us to
increase the velocity in the moving cause, as in levers and pulleys.
However, this  is  not universal  in  machines;  for some have it
reversed, as  the catapulta, the lock of a gun, and also  in many
machines where strength is not the object, but velocity in some par-
ticular movements, as in watches, jacks, &c.
   Whether the effect of a  given quantity of contraction in a muscle
be or be not equal to that quantity depends upon the construction
and  disposition of the parts  to be moved, or the form which  the
whole muscle is thrown  into.  Thus  the effects of some muscles
upon the parts are just equal to  the contraction of  the muscular
fibres ;  such are those which  simply draw parts to them, not vary-
ing the position of the part moved from the right line, as many of
the  muscles of the larynx, the trapezius, rhomboideus, and all of
the panniculus carnosus kind, as the muscles of the face, platysma
myoides, and the muscles  of the skin of animals.
   Another class, whose effects are always known, or are  the- same
in all cases, are  those muscles which  produce  their effects from the
shape which the muscle  is  thrown into,  for instance,  a curve.
Curved  muscles  are  of two  kinds,  viz., those which  are fixed at
their ends, as the abdominal muscles,  pharynx, &c, and those
which are circular, as the  sphincters, heart, and the whole vascular
system.   These  muscles always reduce the circumference and, of
course, the diameter of the circle, which they themselves compose,
in proportion to their quantity  of contraction; but the ultimate
effect here is not in proportion to the quantity of contraction, but
decreases as the  squares of the diameters of such vessels.   But
most parts of the body are so  mechanically formed, acting  as levers,
and the muscles so advantageously inserted, as to produce a much
greater  degree  of velocity in the motion of the  part than is equal
to the contraction of the muscle.  But those mechanical  applica-
tions are so various that  there are no two muscles which act  with
the same advantages, excepting those  that are  in pairs.   On this
application of muscles to levers depends the distinction between
the  absolute  and apparent force  of  muscles, neither of which can
possibly be ascertained with any degree of certainty.
   Every muscular fibre  is capable of contracting with  a given
power, which  power simply must be  always  its absolute force;
but  from the construction of parts  to  be moved, and the applica-
tion of muscles to  those  parts, either an increased  or decreased
effect is produced.
   It is  impossible  to ascertain  the absolute force of a  muscle
because there  is no one known muscle in the  body that we can
throw  into action  separately, and independently of the collateral
effects of others.  And, if we could, there are many whose power
could not be measured by any given quantity of resistance to be 
260          HUNTER ON THE ANIMAL CECONOMY.
overcome, so  as  to  ascertain the power of contraction  of that
muscle, as, e. g., all those which  simply pull bodies in a  straight
line :  but, in those muscles which  act upon the bones in the form ot
levers, if any could be made to act  singly its power could easily
be known.  But  whatever this power is it  must be always the
same; nothing can alter it excepting real weakness in the muscular
fibres themselves.
  As we cannot  separate and ascertain the absolute force of a
single  muscle, so it is impossible to find out the apparent force;
and exactly for the same  reasons that we cannot  find out the abso-
lute.   The apparent force  of circular muscles  will be in a ratio
proportionably to their diameters, and in those which are  inserted
into levers it will always be as the distance of the insertion of the
muscle from the centre of motion,  the angle of insertion, &c.  But
the relative force is not always the same, or it does not  always act
alone in the motion of the parts, for it is often joined with velocity,
and then  it  may become vastly  greater.  But if not joined with
velocity it will  always be less than the absolute, as the length of
lever in the resisting power is longer  than in the  acting one.
  The absolute force of a muscle will always be employed in the
most simple action of the parts.   The most simple action will be
where a muscle passes in a straight line from some fixed  point to
a moveable one, and by its contraction simply pulls the moveable
one towards the immoveable one,  such  as many  of the  muscles of
the os hyoides, and in many other parts of the body.
  As  the circular muscles are commonly  employed in propelling
bodies, and principally fluids, they will  keep up an equal power
upon  the  body to be expelled; for, the  power  increasing as the
fluid  decreases, it is capable of throwing  out the same quantity in
the same time.*
  I observed that the muscles, as moving powers in an animal,
differ from the moving powers in a machine, the production of art,
inasmuch  as every part had its power adapted to the motion it is
capable of, and therefore the motion of any one part did not depend
entirely upon its  own configuration and connexion with some other.
Although  this is  in a great measure  the truth, yet the motion  in
most parts is assisted by actions or the  contrary in other parts, so
that there is a kind of dependence and mutual assistance through
the whole. This does not, however, arise  from any mechanical
construction, but from  a connexion  of the living principle in  the
powers of one part with those of another, which may be  termed a
species of intelligence.
  The motion of parts generally is the motion of a smaller upon a
greater, and the  greater becomes the fixed  point upon which  the
  * It may  be asked, at what point of the  contraction of a muscle  has it the
greatest  power ? Or, does it contract with  the same force through the whole
contraction ? 
         CROONIAN LECTURES ON MUSCULAR MOTION.      261

smaller may be said to move; but we find that there are few mo-
tions, however trifling, but what affect the greater part; therefore
that this motion in the smaller part may be more effectual and an-
swer the intended purpose, the greater part is either thrown into a
counter-motion by its own  muscles, or it is  supported in its place
by them, or it is thrown into the same action with  the small part,
so as to increase it.  Hence the actions of these powers  may be
said to be of two kinds,  immediate and secondary.
  The  first is that which  produces the immediate action of the
part; the second  produces  the assistant,  supporting, regulating
actions, &c.   For instance,  when a  man walks, it  at first might
appear that the only thing necessary  to produce the  ultimate effect
was the motion of the two legs, the body being first thrown suffi-
ciently forwards, so as always to require that motion of the legs to
support the centre of gravity.   But this is not sufficient; it  is ne-
cessary that the muscles of  the  trunk should act, and  regulate the
body so as to support the centre of gravity on all  sides.   If the
right leg moves, the muscles of the left side of the trunk act to sup-
port the whole on the  left  leg, and  vice versa; so that the body
plays upon the motion  of the legs, by which means the legs have
much less to do, and therefore can support it longer.
  In many of the actions of parts of the body other parts  are kept
immoveable, although they would appear to have  nothing to do
with any such actions.  A man  never performs  any considerable
action, even with any of the extremities, without the  trunk  being
more or less affected, so as  to favour the motion  of  the extremity.
We find that we first make a full inspiration and that  all the  muscles
of respiration act, also the muscles of the glottis,  and  of  the soft
palate, so  as to confine the air which makes  the trunk  as rigid and
firm as possible to support or sustain  the actions and motion of the
extremity.
  If an action takes place in  an extremity, where a considerable
effect is to be produced, which can only  be produced  by a consi-
derable velocity, then  the whole body gives it assistance so far as
it is possible for it to do.
  If a man throws a stone, or a blacksmith swings  his  sledge-
hammer, the whole body humours the action, and the  fixed point
is thrown  to a greater distance than ihe setting-on of the arm: the
whole moves from the loins, or perhaps lower.
  Those secondary actions are brought in as auxiliaries, and an-
swer two  very important purposes: they increase the quantity of
action when necessary, and they assist in  easing the immediate
action, so as to allow of a continuance of it, by which means ani-
mals are capable of performing greater actions,  with  more ease,
and a longer continuance.
  Muscles regulate the actions  of others not only by their contrac-
tion but by their relaxation, which last is a kind of negative action.
When a man walks I have  already observed that there are many
muscles acting as secondary agents in the body, so as  to assist the 
262          HUNTER ON THE ANIMAL CECONOMY.
immediate motions of the part to be moved ; but, besides this, there
are many of the same muscles that are gradually relaxing, so as to
allow the alternate motions by imperceptible degrees to creep regu-
larly into one another.
  Perhaps I cannot give a more striking idea of those primary and
secondary actions, with the relaxations, which I have called nega-
tive actions, than  to present to the minds of those  who have some
knowledge  of the  subject what must be going on with the muscles
of a man balancing himself on a slack or tight rope, when the first
or immediate order of muscles are acting with their utmost  force;
where the secondary are assisting in the secondary actions  of the
body, and as it were playing into the hands of the  first;  where
others again are relaxing in proportion as the first  and second are
acting ;  and where the entirely relaxed are waiting the opportunity
to act, when called upon by any change that shall take place in the
position  of the body, which in such circumstances is in a continued
agitation.
23. CROONIAN LECTURE ON MUSCULAR MOTION, No. IV.

   [The manuscript of this Lecture appears not to have been among
those which were accessible to Mr. Clift, and from his copies of
which the Lectures in the present volume have, with his permission,
been printed.  Its absence  may, however, be accounted for, from
the fact that the substance of the Fourth Croonian Lecture was in-
corporated by Hunter in his work 'On the Blood,' (see the Chapter
on the  Vascular System,) as is evident from the Abstract of the
Lecture in the Archives of the Royal Society, the subjoined copy of
which Abstract Mr. Palmer, with the permission of the  President
and  Council, has obtained  for  the  use of the present edition of
Hunter's Works.]

[The Croonian Lecture on Muscular Motion, by Mr. John  Hunter, was read on the
                 25th of May and 1st of June, 1780.]

   '' The construction and general application of muscles  in the
animal body having been discussed by our author in three former
lectures, he now  proceeds to treat of the action of muscles on the
blood-vessels, an inquiry which, however essentially it may contri-
bute to our better acquaintance with the animal ceconomy^has yet,
it  seems, till now  been but little attended to, the existence of mus-
cular fibres in the  system of  blood-vessels being by no  means
obvious.
   " Mr. H. finds it necessary previously to lay down some genera]
principles concerning muscles, which he derives from  their opera-
tions in  those parts of the animal where their uses are well un-
derstood. 
         CROONIAN LECTURES ON MUSCULAR MOTION.      263

   " A muscle he defines such an arrangement of animal matter as,
whilst it is endowed with life, is  fitted for self-motion.  This motion,
he says, consists in the contraction of the muscular fibres, in which
light  he considers it  as totally distinct from elasticity.   And he
ventures to assert that no part of an animal except the muscles is
endowed with  this power of self-motion.  He acknowledges soon
after  that this power cannot be the sole effect of contraction, but
that  there must also be a  power of relaxation, acting alternately,
without which no effect could be produced.  But even  this relaxa-
tion,  he says, is  not sufficient to  produce any effect without a pre-
vious elongation;  and as no muscle is, as such, possessed of this
power of  elongation, he considers it as the effect of antagonists of
some kind  or other, or of what may be called the elongators of the
muscles, and says, that it  is not in all  cases muscular, but some-
times the effect of elasticity, and sometimes even of matter foreign
to the body.  This  leads him to distinguish it into three kinds; the
first,  where it is immediately muscular, or when antagonist  mus-
cles act immediately  upon each  other; the second, when a  muscle
acts upon some other matter, and gives it the power of an antago-
nist, as is  the case in all those muscles that enter  into the formation
of canals or cavities, whose elongation is produced  by other  mus-
cles,  which have  no immediate  connexion with them, but which
force them to an extension  by propelling the contents of the canal,
instances of which we find in the oesophagus, the intestines, and the
bladder; and  thirdly, when the elongation is owing to elastic sub-
stances, which sometimes cooperate with, and sometimes resist the
action  of  muscles;  and  of other powers, such  as gravitation,
velocity, &c.
   " The second  section treats of the application of the muscular
and elastic powers, where both indisputably act.  The joint applica-
tion of these  two  powers   we  are told is very common, though
hitherto it  has been but little noticed.  Elasticity operates where
constant or stationary action is wanted.   Muscles are applied where
occasional action is required; and where both effects  are wanted
both  powers cooperate.  This  is  illustrated by various examples,
among the rest that of a bivalve, which has a muscle between the
two shells,  for the purpose of closing them, and an elastic ligament
in the joint, which constantly tends to diverge them.
   "Another instance, much more to the present purpose, is that of
the elastic cartilages and membranes of the trachea, and its branches,
which maintain  an equilibrium  by counteracting the tendency the
muscles of respiration have to contract that channel.
   " In most parts of the body the muscles are so well defined that
their  existence  is evinced   by merely viewing their structure and
colour. But this is not always the case, and we especially find that
in the blood-vessels no traces of muscles are distinguishable by mere
inspection.
   " Here  then other modes of  information  are  requisite, and our
author proposes  two.   The  one  is their effect when we  see actions 
264          HUNTER ON THE ANIMAL CECONOMY.
that are in every respect muscular, although no muscle be distin-
guishable by the eye; and the other the change that takes place after
death, when, as Mr. H. has observed, in many cases the power of
contraction preponderates so as to  stiffen all the muscular parts;
and when, if the muscles thus contracted be afterwards stretched
or put into what in the living body may be called its relaxed state,
they remain thus relaxed without showing the least tendency to any
further contraction.    These circumstances  mark  the  difference
between muscular and elastic parts, since this latter power continues
to act after death much in the same manner as it did during the life
of an animal.
  " These two modes of information are next applied in the exami-
nation of  blood-vessels,  which, our  author previously observes,
seldom bear any visible marks of muscular construction, and scarce
ever admit of examining from  their effects in the living body, on
which account the second mode of information must be adopted as
the likeliest to furnish  some lights in this inquiry.   He made a set
of experiments on  the blood-vessels of a dead horse, which were
taken out so carefully as not to affect in the least either their texture
or degree of contraction.  They were examined both in their natural
state and after they had been opened, and stretched different ways,
by which  means the different actions of the  muscular and of the
elastic powers become easily discernible.   The following  are the
principal facts that resulted from this examination :
  "Every part of the  vascular system is not equally endowed with
muscles; the larger vessels,  especially the arteries,  being chiefly
composed  of elastic substances, whilst many parts of the  smaller,
or what are called the capillary vessels, appear to be almost entirely
muscular.
  " In the middle-sized arteries two substances  are visible to the
eye, that towards the inner coat being evidently darker in colour,
and of a  structure somewhat different from the outward.  The
relative thickness of these coats differs  as we recede from the heart,
the interior becoming considerably thicker in proportion to the
exterior;  whence it evidently follows that the external diameter of
the duct  is not to be inferred  from its  external  thickness, this
being always proportionably greater as the vessel diminishes in size.
Both these coats are in some measure elastic, but the external is
more so than the internal;  whence  it  may be judged that  it is the
internal that is endowed with muscular properties.   This indeed is
confirmed by a variety of experiments, in which it was  found that
the inner  surface  after death was  considerably more contracted
than the outward, the latter  being thrown into longitudinal corruga-
tions, which could  only be the effect of the greater transverse or
circular contraction of the latter.
  ;* It has further been observed that  this muscular contraction is
chiefly in  the transverse direction, and seldom if ever longitudinal
  " The physiological application of these facts, especially to arte-
ries, is briefly this.  The musclar contraction being chiefly circu- 
         CROONIAN LECTURES ON MUSCULAR MOTION.      265

lar, and tending to lessen the diameter  of the vessel, the  animal
ceconomy would suffer  greatly if in the  larger arteries, where this
contraction is greater in proportion as its diameter increases, some
power did not counteract this tendency so as to maintain a middle
state or equilibrium.  Thus also when muscular parts are too much
distended, which in  large  arteries will often happen on account of
their vicinity to the heart, a similar power is requisite to contract it
to its natural size  or tone.   In  both cases the elastic power pro-
duces the necessary effect, and  it seems  to follow hence that this
power  must always be  proportionally greater in the larger  vessels
than in the smaller ones.
   " A Table, exhibiting at one view the results of the above-men-
tioned experiments concludes this lecture."*
24. CROONIAN LECTURE ON MUSCULAR MOTION,No. V.

                       FOR THE YEAR 1781.

      [Read before the Royal Society, June 14, by Mr. John Hunter, F.R.S.]

     Of the Contraction and Relaxation of Muscular Fibres.

   Muscular motion differs from every other motion in  matter; it
is a motion taking place in the component parts of a muscle, and
not a change of their relative situation.   It is an uniform  approxi-
mation, and receding in all  the  parts; the size, construction, and
connexion of these are as yet not known: it is similar, as far as we
can discover by our senses, to elasticity;  in both cases  the motion
is produced in the component parts, which we are  as  yet unac-
quainted with, and only see the ultimate effect.
   For the  better investigating  this  motion  in  muscles, we may
divide the general motions in matter into four kinds.


  * [The irritability, or muscularity, of part of the coats of the artery contended
for in the  preceding lecture by Hunter, has since been demonstrated experi-
mentally, first, by Dr. John Thompson  of Edinburgh, and subsequently by many
other physiologists; in whose experiments distinctcontraction of the small arteries
was produced,°not only by mechanical (Wilson Philip, Hastings, Kaltenbrunner)
but by galvanical irritation.  (See Wiedemeyer, Experimenta circa Stalum San-
guinis et Vasorum in Injlammatione, Monachii, 4to., 1826, and the Bibliography
of the Vascular System, vol. iii., p. 226.)   The muscular action is easily seen
by dropping  water colder than the atmosphere upon the capillaries in  'the
mesentery of a frog, which thereupon contract both longitudinally and transverse-
ly, and after a little while resume their  ordinary dimensions.  Nevertheless
the best chemists  agree in classing the fibrous coat of arteries with the non-
albuminous textures, as cellular tissue, cartilage, &c.  The ultimate fibres of
he middle coat, viewed microscopically, are smooth, branched,  and anastomose
reticularly, like the fibres of involuntary  muscles : they present a remarkably
clear dark outline.]
                                  24 
266          HUNTER ON THE ANIMAL CECONOMY.
  The first is the motion of whole bodies by means of an external
impulse, the vis inertia of the body being overcome.
  The second  is the motion  from  attraction of one  species ot
matter to itself or  to another  species, as  wholes.  Of this kind
is gravitation, perhaps  magnetism and electricity, probably also
cohesion.
  The third kind of motion is  from  chemical attraction, where,
besides the attraction of whole parts, there is an elective attraction
between the particles of one kind of matter and those of another,
as it were drawing them out from the general mass.   This can
only happen when suspended in  a fluid or in  the form of vapour, no
other form admitting of the motion of particles among themselves.
Repulsion produces a similar motion among the parts.
  The fourth kind of motion is muscular, arising most probably
from construction, and a principle in action very different from the
attractions in common matter.
  This action and the others are equally unintelligible, the general
effect alone being evident  to our senses.
  From the effect in muscular motion, we should be inclined to sup-
pose that there is an approximation of the parts in one  direction,
which in the whole produces a  visible contraction.
  It is natural to suppose  that all muscular  fibres act alike;  that
every fibre in every muscle  when in  action  is under  exactly the
same circumstances: therefore whatever variety may  appear  in
muscular action, or difference between the action of different muscles,
must depend upon the various causes and intentions of these actions.
  A muscle in action as it contracts becomes more dense or hard,
and therefore hpriori we should suppose it becomes less, as we can
form no  adequate idea of the same substance becoming firmer  or
harder without either an approximation of its parts, or an addition
of new matter introduced into all its parts, or a particular  position
of the  constituent parts  of a muscular fibre, so as to become im-
moveable while in that position.
   One circumstance, however,  which makes muscular fibres firmer
when  contracted in the living  body  is, their always  overcoming
some resistance in  such contraction, which  puts them more or less
in the situation of a stretched cord.
   Take the unattached  hairs which compose the strings of the bow
of a fiddle, and they will  feel pliant  or soft; but when put upon
the stretch they will feel  much  firmer.  An elastic body also, as
India rubber, feels  much  firmer  while  stretched  than  when  con-
tracted and  at  ease, by its natural elasticity.  A muscular fibre,
however, in the state of tension between the two points is little  in-
debted to this  cause for its firmness, although  it  will  increase the
effect produced by the position of its component parts ; for a mus-
 cular  fibre unattached is  very  much  increased in hardness while
 contracted, as in crimped fish,* and  in  the flesh of all  animals
   * [Sir Anthony Carlisle found that the contracted muscles in crimped fish had
 not only acquired  a sensible rigidity, but also an increase of specific gravity.
 See his ' Croonian Lecture for the year 1804,' Philos. Trans., 1805, p. 1.] 
         CROONIAN LECTURES ON MUSCULAR MOTION.     267

allowed to die so gradually that the muscles, from the stimulus of
death taking place, contract: but a muscle is as firm and as strong
in all its degrees of contraction as it is in its full contraction, if not
firmer and stronger than in its ultimate;  therefore cannot be called
contraction.   It is its proximity of its parts arising from that attrac-
tion, not from the proximity of such parts mechanically, but  at-
tractively.
   Many authors of authority, as well physiologists as others, have
attempted to  explain the contraction of a  muscular  fibre ; but,
however ingenious their opinions may be, none of them completely
account for any one particular, relative to muscular  contraction:
I shall, however, mention them, with the objections to which they
are liable.
   In the investigation of this subject the following apparent altera-
tion in the figure of a muscular fibre has  been principally attended
to: When a muscle acts, it  increases in thickness, and  becomes
visibly firmer in texture, therefore each component fibre of the mus-
cle must be  supposed to undergo the same change;  and  many ex-
periments have been made to  ascertain whether this increase of
thickness in a muscular  fibre  is in proportion to its  decrease in
length, but hitherto without effect: probably  the only method of
ascertaining this fact is,  to determine whether a muscle in the state
of contraction is really increased or diminished in its  bulk.
   Haller, in his Elements of Physiology, asks the following ques-
tions:  "Does a muscle really increase in bulk in its  action?   As
a muscle, when  it acts, becomes shorter, and  swells, we may next
ask, Do these two changes, contraction and  dilatation, compensate
each other] that is, Is there  the same quantity of matter in it at
both  these  periods'?  Or does a muscle in action really lose in its
size 1 or does it gain in bulk what it loses in length 1   Both sides
of the question have had their advocates."
   Borelli, to find out whether a muscle really  had an addition of
new  matter in its  contracted state, and thereby became heavier,
made the following experiment:
   He placed a naked  man upon a table suspended  upon a point,
which supported it directly under his buttocks, in which situation
he was perfectly balanced.   He was then desired to act with  the
muscles of  the lower extremities, but he still kept his balance, no
change taking place in the equilibrium.  (Borelli, vol. ii., p. 39.)
   This experiment was made most probably upon the supposition
that some additional matter was to  flow from the brain along  the
nerves, or  from the heart  along the vessels  to the muscles of the
extremities, so as to render the upper part  lighter, and the lower
part heavier.   If it was  to come  from the brain, it was conceiving
the supposed animal spirits to  be heavier than air, of all of which
we are wholly ignorant.
   The celebrated  experiments  of Goddard, Glisson,  and Swam-
merdam are quoted, to  prove that  muscles lose in their bulk while
in action.   They put a muscle or a  whole limb into a glass vessel, 
268
HUNTER ON THE ANIMAL CECONOMY.
 and filled it up with water;  they then  made  all the  muscles
 act  at once ;  or if a single muscle, they irritated the nerve, ana
 made it contract, during which time they attended to the motion in
 the water, and its rising or falling was to determine whether tne
 size of the muscle was increased or diminished.
   Swammerdam, in trying this experiment with a  single muscle
 (the heart of a frog), saw the water sink in the  contraction ot that
 muscle, and rise in  its relaxation.                          .   ,
   The result of this  experiment has been very differently explained.
 Swammerdam  himself doubted its being conclusive, believing  the
 air might  be compressed during the heart's action ; but we have no
 proof of the presence of air in  a muscle in the simple state of  air.
   Boerhaave and Sauvages accounted for the water descending by
 the blood  being pressed out by the contraction of the muscle, which
 blood was returned  into it bv the relaxation, and raised the water.
 This certainly would be the'case in  the experiment made upon a
 whole limb: for  we know, from every day's experience, that in
 bleedings  from the arm the blood is thrown out more forcibly while
 the muscles are in action:  therefore there is less blood in the vessels
 of the limb when the muscles are contracted  than in a state of
 relaxation, and of course the limb is less in bulk at that time than in
 the other : but when a  single muscle or  a whole animal is immersed
 in water,  whatever loss the muscle has  in  its substance must  be
 gained by  the water, so that the whole can neither be diminished  nor
 increased.
   Hambergerus  tied  a string round a  man's arm, and found that
 during the action of the muscles it  cut  him ;  he therefore  thought
that  muscles  in  action were increased  ; but  the  experiment only
proved that it became thicker, which is generally allowed.
   It has  been objected to  such experiments, that if a person acts
only with  one  set of muscles, their opponents become stretched or
relaxed  in proportion, keeping  up an  equilibrium in the part: as
 antagonizing muscles, however, never bear a just proportion to  one
another in strength, it follows, that if we act with the strongest set
of muscles the limb  will of course become thicker in the proportion
that the strength of the acting muscles bears  to  the strength  of the
relaxing ones,  and vice versa.
   To ascertain with as much precision as possible whether a muscle
 really alters in size or not  when contracted, I repeated  the experi-
 ments of Goddard, Glisson, and Swammerdam,  but  in such a way
 as to have little or no doubt what  was the effect.  I got a glass
 blown which contained almost a gallon  ; its mouth was about three
inches over, to admit its receiving a pretty large muscle, and was
 fitted with a  ground-glass stopper, which  was water-tight,  and a
 glass tube was fitted into  this stopper,  so as to  communicate with
 the cavity of the glass, being at the  same time  water-tight.  This
 apparatus could  be  filled with water, and have the water stand at
 any height in the tube which might be required, so as to give with 
         CROONIAN  LECTURES  ON MUSCULAR MOTION.      269

great nicety the comparative  size (should there be any difference),
of a muscle when contracted and when  relaxed, while immersed
in it.
  The muscles best adapted for  experiments of this kind are those
which have no antagonists, for in that case the contraction of one
muscle produces the elongation of the other.   The muscle should be
wholly detached, having  neither origin nor insertion, as a muscle
cut out of the  body, or cut from  its attachment, as in crimped fish:
those muscles  however arje best which have no natural attachment,
as the heart.
  In repeating such  experiments it will be hardly possible  to  have
the result of two  exactly the same, for no  two  muscles will be
equally relaxed at the  beginning of the  experiment, nor will  any
two muscles  contract  equally;  but if  there  is one universal
general effect  taking place in all  of them, that general effect be-
comes the  result  of the experiment,  and is  what is to be at-
tended to.
  Experiment 1.   I killed a dog instantaneously,  and took out the
heart as  expeditiously as  possible, and  put it  into the glass filled
with water, and immediately after putting in the  stopper with the
glass tube fixed in it.   I now observed the height at which the water
stood in  the tube.
  The heart had so far lost its action as not to contract and relax
alternately, having only the power of contraction from the  stimulus
of death, and when put  into  the water was perfectly relaxed.   It
was allowed to remain in the water some  hours; and it  was ob-
served, that by its  apparent loss of bulk it  had  contracted  con-
siderably;   and we  also found that the water  in  the tube  had
fallen.*  The next thing to be done was  to  ascertain how much
the heart  had lost  in  size,  which was  known  by the  quantity
necessary to fill up the glass to the first height, which was sixteen
grains.
  The size of the  heart was equal to two ounces  six drachms,
and thirty-eight grains of water, that is, 1328  grains,  so  that the
contracted  state was to  the  relaxed as  82 to 83, or Ad part  of
the whole.
  Experiment 2.   I  took the heart of a sheep, whose  size was equal
to  13 ounces or 104 drachms of  water;  it lost  in  contraction 1
drachm; so that the contracted  state was to the  relaxed  as nkth
part of the whole.
  Experiment 3.   I  took  a live eel, which was gutted, to remove
as much as possible  everything not muscular, and then crimped,  to
destroy the attachment of most of the muscles.  The eel was equal
to 14 ounces and 133 grains, or  6853 grains  of water, and it lost
in contraction 39 grains, or  iith part of the whole.f

  * It is to be observed that the water was kept in the same degree of heat through
the  whole of the experiment.
  + [In the experiments above detailed Hunter drew his conclusions, as to the
change of bulk in a muscle during contraction, from the effects observed in the level
                              21* 
270           HUNTER ON THE  ANIMAL CECONOMY.
   As  this  animal was  composed of muscles,  bones,  &c., some
allowance  is to  be  made for these  parts, which will  account  in
some measure for the difference in the result between this and the
hearts, although in the experiments on ihe  hearts  there  is  a con-
siderable  difference  between  the two,  arising  from  the  reasons
above mentioned.
   It appears, however, upon the whole, that a  muscle  loses more
of its length than it gains in thickness, unless the apparent difference
arises from an universal approximation of all its parts.
   As a muscle loses in its general size by the contraction of the
length of its fibres, we cannot suppose that'eontraction to arise from
the introduction of  additional matter into  those fibres; therefore
the opinions that a muscular fibre is a hollow tube from  end  to end,
or a chain  of cells of various shapes, either rhomboidal  or circular,
according to the ideas of  the authors  of  such  opinions, and these
cells being filled with foreign  matter,  must  fall to the ground ;*  m-

of the surrounding fluid, after the last contraction of the part or ' rigor mortis.'   In
Mr. Mayo's well-known experiment, which  is similar to  the first of Hunter s,
the ordinary contractions of the ventricles of a dog's heart, alternating with re-
laxations of the same parts, produced no perceptible change in the level of the
water in the tube.a   In comparing the above experiments, one cannot  fail to be
struck with the period during which the muscular contractions of the dog's heart
continued.  But as Hunter killed his dog instantaneously, it was probably by some
sudden concussion or injury to the brain, when the  action of the heart  would be
arrested, and the last contraction only would be witnessed, notwithstanding the
expedition with which it was  taken out. In Mr.  Mayo's experiment the dog
was killed by hanging, and the ventricles of the  heart continued  alternately to
contract and dilate for a considerable time.  Barzolotti, Prevost and Dumas, who
performed similar experiments  on smaller portions of flesh, also found no change
of level to take place in the surrounding fluid during the contraction  of the muscle.
Gruithuisen and Ermann,b on the contrary, observed, like Hunter, a slight change
in the bulk of the muscle during contraction.  Krmann introduced into a glass
vessel the posterior half of an eel, the intestines being removed.   A metal wire
was inserted into the spinal marrow, and a second into the flesh, and these were
directed so as to be brought into communication with the pole  of a galvanic bat-
tery.  The vessel was then filled with water, so that a narrow tube, in which the
apparatus ended above, was filled.  In completing the chain, and during the con-
traction of the muscles, the water fell  in the tube  four or five lines, and again
rose to the opening, when the muscle relaxed.
  If, however, the muscular fibre, which is generally admitted to have  increased
in density, and, according to the experiments of Sir Anthony Carlisle, in specific
gravity, during contraction, has really diminished  in bulk, the difference is so
trifling that we can hardly avail ourselves of it in elucidating the  nature of mus-
cular contraction.]
  * [It is  now generally admitted by microscopical observers that the ultimate
muscular fibre is  solid.  The voluntary muscular  fibres  (' secondary fibres' of
Prevost and Dumas, 'ultimate fasciculi' of Mfiller,) in the vertebrate classes,
and those  of insects, arachnidans, crustaceans, and cirripeds, present  a micro-
scopical character which distinguishes them from every other animal  tissue: it
consists of close-set, parallel, transverse, or slightly oblique and sometimes slicrht-
ly curved striae.  The fibres which present these strise are divisible into component
fibrillae, which have a knotLed or beaded structure ;  this I  have myself  observed
a Anatomical and Physiological Commentaries, vol i  p 12
i> [Gilberts Annalen, 40.]                         "' l 
          CROONIAN LECTURES ON  MUSCULAR  MOTION.      271

 deed, this idea of a muscular fibre being a chain of cells does not
 account for any one phenomenon attending  muscular motion, and
 is directly contradicted by two  circumstances attending muscular
 contraction: the first of these is the muscle becoming rather less
 than larger in its contraction, which is just contrary to what  must
 have happened  if the contraction had  been  owing to that cause;
 the second is, that a muscle is capable of contracting much  more
 than one-third of its  length,  and indeed, as far  as we  yet know,
 having no limitation, which could not  possibly happen if they were
 tubes capable of receiving foreign  matter into  their cavities; for
 according to that idea, a muscular fibre should  become thicker in
 its contraction in proportion as the diameter of a sphere is greater
 than that  of a  cylinder of the same area, which would  be an im-
 mense increase.
   Although a muscle becomes  on the whole somewhat less  in its
 contraction, and has its ends  brought considerably nearer together,
 yet it  cannot  be called attraction, for there is nearly the  same
 reason for supposing a lateral  repulsion, as the  muscle  swells out
 laterally almost as much as it contracts in the other direction.
   I do suppose that a muscular fibre is not one uniform body from
 end to end, but is made up of parts, which may  be called the com-
 ponent parts of a muscular fibre; and I am apt to suppose that a
 change takes place in the position of those parts, during contrac-
 tion, and this alteration diminishes the extent of  those parts in one
 direction  while  it is increasing them  in  the other, although  from
 the  experiments  it appears  not to be in the same  proportion; but
 what that  alteration is  I shall not pretend  to determine.*

 in the human voluntary fibre, and in that of the mole-cricket.  Some physiologists
 suppose that the transverse striae result from the lateral apposition of  the knots
 on the parallel fibrillse.   The  muscular fibres of the  mollusca and radiata, and
 the involuntary muscular fibres of the vertebrata, with the exception  of those
 developed in the vascular layer of the germ disc, as the fibres of the heart, do not
 present the striated character.]
  * [According to the observations of Hales (Heemastatics, p. 59), and of Prevost
 and Dumas (Magendie,  Jourpxal de  Physiologie, iii., p. 301), the change in the
 muscular fibre, at the moment of contraction, is from a straight to a zigzag line :
 the observation has been generally made on the rectilinear parallel fibres of one of
 the thin  abdominal muscles (the rectus) of a young frog, stimulated to  contract
 while under the microscope; and the conclusion  is admitted as an established
 fact in the most recent works on physiology.   I have been led to doubt this fact,
from observing the contraction of the  muscular fibres in small Filarias (such as
commonly infest the abdominal cavity of the cod), and more especially from
observing the contraction of the retractor muscles of the tentacles of a species of
 Vesiculetria of Vaughan Thompson, a compound polype-like animal, which,  under
the guise of a Sertularia manifests a much higher  type of organization.  Here
each separate fibre of the retractor muscles is seen with great distinctness, and is
characterized by a single knot or swelling in the middle.  In the act of retracting
the tentacles the fibres become shorter and thicker, especially at the central knot,
 but do not fall out of the straight line.  After  the retraction has been effected,
the fibres fall into a wavy or zigzag position :  but this is characteristic of  their
state of relaxation  under the circumstances which bring their two attached ex-
tremities nearer each other.  In like  manner, in the parallel longitudinal  fibres
of the Filaria, it is most evident that, at the moment of contraction, they become 
272
HUNTER ON THE ANIMAL  CECONOMY.
   Muscles have a disposition to throw themselves into wrinkles or
 corrugations when not in action, and when the position of the part
 moved by these  muscles is  such as allows the muscle to be in its
 shortest state, as in the biceps-flexor-cubiti after having bent the
 arm.  If it is kept in that position  by any other power, the biceps
 will leave acting and fall into wrinkles, adapting  itself to the short
 distance  between  its origin and insertion; so that these wrinkles
 are  a kind of substitute for the contraction that was in the muscle.
   The  greatest  strength in a muscle  while in  action  is probably
 when it is half contracted, as we find that in all great exertions of
 muscular strength, where ultimate actions are  to  take place, the
 muscles employed are  never allowed to relax their full relaxation,
 or contract to their full contraction.
   When a man walks  with  a heavy load his knees are a little bent,
 even of the  leg he stands upon, which  supports the whole while he
 is moving the other. The same thing takes places if he is weary ;
 but  if  strong  and full  of activity his  perpendicular joints may be
 kept pretty straight.
   The  same  thing also takes  place  in old people from the same
 cause;  for as they become naturally  weak, they become, like the
 strong, loaded  with a heavy burden, therefore  take on the  same
 modes of action: the knees are never straightened, the back bent
 forwards, and all the parts that are constantly in the action of sup-
 port are all  getting out  of the perpendicular, in which perpendicular
 state, although they might  be mechanically stronger, yet they are
 muscularly weaker, therefore get into that  position in which the
 muscles can  act with the greatest advantage.
   The relaxers, which  become  the sustainers  of the  muscles in
 action, never  allow themselves  to  relax to their full extent while
 the  contractors  are carrying on the motion of a part, as it would
 produce weakness.
  The  relaxation  of muscles when  contracted involuntarily, but
 from obnoxious  stimuli, will not relax by the will;  nothing but a
 counter-stimulus of necessity can, and  even that with difficulty.
 For  instance, if we attempt to breathe  obnoxious air, or if anything
 touches the glottis, it immediately shuts, and it is out of the power
 of the will to relax it;  but the stimlus of the necessity of breathing
 brings  it to again.   A muscle that  has but one  determined use, or
 rather  a muscle that has but one  point of orgin  and one  point of
 insertion, always  acts  wholly  when put  into action, so as to bring

 shorter  and thicker, but do not  alter their rectilinear  position until the  action
has ceased, when they fall, like the parallel  nervous chord, into zi^za^ folds,
which continue until effaced by the  restoration of the  part to its usuaMength
through the action of the exterior transverse fibres.
  On relating these observations to my friend Dr.  Allen Thompson, he informed
me that on repeating the experiment of Hales and Prevost on  the fro$r  he had
observed single fibres continuing in contraction, and being simply shortened  and
not falling into the zigzag plica ; and he was led to suspect, from this and other
appearances, that the zigzag arrangement was not produced till after  the act of
 contraction had ceased.] 
         CROONIAN LECTURES ON MUSCULAR MOTION.     273

about its effect on the part of insertion ; I believe never one part
of the muscle only, or only a few  of its fibres, but the whole.  This
is not the case with muscles whose origin is broad and its insertion
narrow, whose insertion is  broad and its origin broad, or whose
origin is  narrow and insertion broad.
  But in spasm in a muscle a very few fibres may be seen to act;
in short,  any number may act, as it is not motion of the part that
is the intent of the  action.
                          Relaxation.

  Muscular fibres have a greater power of contraction than what
is barely sufficient for the extent of the motion of the parts upon
which they are designed to  act.   This is illustrated in the shell-fish
called bivalve, for the  muscle in that fish brings the two shells to-
gether;  but if one of the shells  be broken, so  as to allow of a
nearer approximation of the two insertions of the muscle, we find
that they are brought  nearer.  It is also  evident where the tendo-
Achillis or patella is broken, for  when that happens the fibres  are
allowed to contract to  the  full extent of their original contraction,
and the parts heal in that position; in such cases the muscle is be-
come shorter the  whole length of its natural  contraction, and  the
tendon is become so much  longer ; and in this case, if the muscle
was not possessed of a  greater power of contraction than was be-
fore made use of, or did not acquire  a greater  power, no motion
could now take place, whereas we find  the  ultimate quantity of
motion produced.
  If the power of contraction was limited  to the quantity  produced
in a straight muscle, the same kind of fibres, when forming sphincter
muscles, could not answer the intended purposes, as a greater power
of contraction is required.
  That  the same length of  fibre is not absolutely necessary to pro-
duce  in all cases  the same  effect, is strongly evinced,  by  the fibres
of the gastrocnemius  muscle in  the African  negro, being shorter
than in the European, yet  producing  exactly the same quantity of
motion in the joints which   they  move.   This  takes place univer-
sally  in the Africans, and now and then is  met with in men of other
nations.
  This difference  in the length of muscular  fibres  is  a  principal
reason of the difference in the outline of most men from one another;
it is at least a secondary cause, and should be particularly attended
to by painters and sculptors, as it is a distinguishing mark between
original nations.
  The contraction of a muscular fibre is produced by the  following
causes :  simple  mechanical  pressure, as  touch, the pricking of a
pin, &c.; simple  impression on another part which acts upon this
by sympathy. 
274          HUNTER ON THE ANIMAL CECONOMY.
  It is also produced by  properties of  matter  which are not me-
chanical, as the essential oils, salts, acids, &c.; by affections of the
mind and intentions of the  will by means of the  nerves;  by the
circumstances of the body itself at the time, as wajit, repletion, &c.;
and even by death itself.
  An animal  that dies so slowly as to allow the stimulus  of death
to be felt  by its muscles,  has those muscles  so contracted as to
become stiff; whether this  contraction is equal to the greatest
power of contraction of the  same muscle, in such a position of the
parts in the living body, I do not  know.
  In order, however, to  ascertain how much a  common  muscle
contracts  from the stimulus of  death, I cut out a muscle  from a
horse just after  it was killed, and  found that in the action of death
it had contracted one-third, and that the muscle so contracted had
become one-fourth thicker in its diameter, a proportion I believe it
would have  kept  in the living body; also the same muscle, when
stretched, or when  put into  what in the living body may be called
the relaxed state, did not again contract.
  The  contraction of muscles from the stimulus of death  is a
stronger contraction than the attraction of cohesion of the muscles
themselves; therefore when a muscle so contracted is attempted
to be elongated it  generally tears asunder: but this is not  always
the case,  it only  takes place under certain circumstances; it is
with respect to the muscle itself in proportion to the power  of con-
traction of the muscle, for  we find it takes place much oftener in
those that die of violent deaths, especially when  they die of strong
convulsions;  it  seldom or ever takes place in those which die of a
disease  of some standing, for in them the muscles have lost in some
degree  their  absolute  power of  contraction; as  also the  disease
may be such  as has in some degree destroyed the stimulus of death
upon  the  muscles, so that their contraction will be less, although
their power may  be pretty strong.
  It would appear from the above that  muscular contraction is not
simply an approximation of the parts of which a muscular  fibre is
composed.
  What the  difference is in a muscular fibre between its  relaxed
state and the  contracted, perhaps  may never be known.
  Relaxation would appear to be a natural consequence of the con-
traction having answered its end or fulfilled its purpose; or it may
be supposed to  have got rid of its stimulus by this action, the stimu-
lus ceasing to have power when the action has taken place  ; there-
fore relaxation naturally occurs  till excited to  action by  another
sitmulus, of which it is susceptible.
  Relaxation might be supposed to be a simple cessation of action,
but I think it is not;  it appears  to  me to be a power as much de-
pending on life as contraction ;  for if it was simply a  cessation
of action,  muscles would  become relaxed that had contracted by
the stimulus of death whenever absolute death took place, which is
not the case; on the contrary, it takes probably as much force to 
         CROONIAN LECTURES  ON MUSCULAR MOTION.     275

overcome this contraction as the same muscles would have done
when acting with all the power of the will in the living body.
  From  the violence necessary for the elongation of a muscular
fibre after death, it would appear that the position of the component
parts of a fibre in any degree of contraction is such as requires force
to alter or  remove  it, and, whatever that position is, it can be in
part drawn out as if only in part contracted, or wholly drawn out;
and in this operation of drawing out or relaxing a muscular fibre
after death, we may observe there is a recoil or reaction in a certain
degree when the elongating force is removed, becoming in this
respect similar to elasticity.   This recoil, however,  is not extensive,
although it takes place in every degree of relaxation, from  the most
contracted state to the almost totally relaxed state.
  I first  observed this recoil in a man who  died in convulsions in
St. George's Hospital, from a fever, attended with  delirium, which
was brought on by a hurt on his arm, which  inflamed  considerably.
A few hours after death  his  muscles were stiffer  than usual, and
extremely well marked through the skin, which induced me  to make
the following experiment on the relaxation of muscles.  I laid bare
the rectus muscle of the thigh, and separated it from the other  mus-
cles without stretching it; I then passed  a thread behind it and
inclosed  the muscle, and cut the thread off where the ends  met.
Upon bending the knee the muscle was stretched, and I found that
the ends of the thread were lapped over each other.   Upon mea-
suring the difference it was one-eighth of an inch diminished from
what it was in the contracted state.
  I was much surprised by a considerable degree of contraction in
the  muscles,  similar to elasticity, for they evidently contracted a
good deal after being  stretched.  I suspected that this had arisen
from some remains of life, and therefore waited till the next day,
when the same thing happened.
   If, in  stretching a contracted  muscle after death, the fibres are
not drawn out beyond this power of recoil,  the whole contraction
of the muscle (whatever quantity it is) continues the  same;  but if
the muscle is drawn out further than this power of recoil,  then the
muscle becomes so  far relaxed, but no further;  for instance, if the
recoil is the one-twelfth of an inch, and the muscle  is only stretched
so far, then the muscle will contract again one-twelfth of an inch;
but if it is stretched one-sixth of an inch, then it  will still only recoil
one-twelfth, the other one-twelfth being the  absolute  relaxation of
the muscle.
   From all that is mentioned above, I think it will appear that re-
laxation of a muscular fibre depends upon life as much as  the con-
traction, neither the one nor the  other being produced after death
by  any property in  the muscle.
   The causes of relaxation are few ; the will is perhaps the princi-
pal one,  although not in all muscles.  Emotion of  the mind would
appear to have a power of stopping the action  of  the heart, but is
perhaps  only hindering a new contraction. 
276          HUNTER ON THE ANIMAL CECONOMY.

  The contraction and relaxation of a muscle are always adapting
themselves to the motions of the parts  on which they are to act,
so that if a joint continues bent  for sometime the muscle will retain
it in that situation, and any extension of that joint will put  the mus-
cular fibres  on  the stretch.  This is not, as has been supposed, a
contraction of the tendon, but a contraction in the muscle, to adapt
it to the  remaining motion in the joint, this half contracted state
becoming now  the state of relaxation from  which the  muscle is in
future to produce its action.  The point of relaxation of a muscle,
therefore, is always the extent of motion in the joint, and the quantity
of contraction of a muscle is always equal to the full motion of the
joint on which  it acts, and if the joint loses part of  its motion the
muscle also loses a proportionable degree of contraction, so as still
to be adapted to it.
  Muscles, however, so contracted, may be gradually stretched to
their original length, and recover their  original action, as the biceps-
flexor-cubiti after inflammations, and  abscesses in the arm.
  Muscles may be also stretched beyond their original length, and
still retain their use, as those of the belly in  dropsies.
  These circumstances prove that accidents to the body are pro-
vided against in its construction; for if the muscles remained in the
half-bent state in the cases above  mentioned, the length of muscle
would be too great for the quantity of motion, and the first part of
its action would produce no effect upon the joint.
CROONIAN LECTURE ON MUSCULAR MOTION, No. VI.

                     FOR THE YEAR 1782.

     [Read before the Royal Society June 13th, by Mr. John Hunter, F.R.S.]

An inquiry how far, and in what instances, the density or firmness of
               a Muscle contributes to its strength.

   In comparative experiments respecting animals, where the actions
of life are attempted to be imitated in  the  dead body, we  should
attend to every circumstance and see whether there is really any
kind of similarity in the experiment.  But, where life is absolutely
necessary for the action, on one side, and the action is imitated only
so far as regards the mechanical mode of performing it, the resem-
blance between the  vital  action  and  the  experiment is in reality
very remote.
   To suppose that the action of a muscle should be equal, more or
 ess, with its mechanical strength when dead is absurd, because they
bear no analogy.  The action of a muscle is as unlike its mechanical 
         CROONIAN LECTURES ON MUSCULAR MOTION.     277

resistance as the effects of the  irritability of a living body upon
impression is like the mechanical effects of the same impression;
the mechanical effects being the same in the living as the dead.
   The action of a muscle is stronger than its mechanical resistance
in the dead body; that is, its power of contraction is greater than
the attraction of the cohesion of its fibres.
   These facts can only be ascertained by experiments on the power
in the living body, opposing them with the resistance in the dead;
but as a muscle is in very different states in contraction and relaxa-
tion, even in the living body, and  as  the experiment is opposing
contraction to the state of relaxation, the  experiment is not con-
clusive:  it does not prove what it  is meant to prove.
   The subject  can and should be viewed in several  lights.   A
muscle is first to be considered in  two points  of view; the relaxed
state, where it is only united by the common attraction of cohesion
of that muscle, and is probably as  mechanically strong in the dead
as the living; but they may be  considered in  the contracted state
both in the dead and the living, for although a muscle does not con-
tract after death, yet it often contracts in the act of dying;  and
death does not produce a  relaxation, therefore it is to be presumed
that the position of the parts of the muscle so contracted remains in
the same state, and therefore such muscle affords an  opportunity of
making comparative experiments between it  and one in the living
body so contracted.
   How far the same muscles  in  the dead body, when fully con-
tracted, could be relaxed by the same force as when in the living
state, I do not know.   It is  certain that a muscle in  health, and
which feels the stimulus of death strongly, contracts with consider-
able force, and requires  a considerable power to  overcome it;
therefore the relaxation of a muscle, voluntarily contracted, must
always be an act of the mind, or a cessation of action of the mind
upon that muscle.  But when a muscle  takes on an action without
the mind, either in diseases, as the involuntary actions of voluntary
muscles, or by the stimulus of death (the immediate cause of action
being, I conceive, the  same in  both), then a relaxation from  the
mind cannot take place in either, because the mind had  nothing to
do with the first, and it did not exist in the second.  So  that those
involuntary actions of voluntary muscles arise from a stimulus  in-
dependent of the will, and in those where it goes  off it is because
that stimulus can cease, and the part being alive  a relaxation  can
ensue;  whereas in death a relaxation cannot  ensue, because a ces-
sation of the stimulus cannot ensue, that cessation being an  act of
the living body.
   To oppose an experiment on muscles in the dead body with  one
in the living, the muscles should be always in similar states, for a
muscle contracted is thicker than natural, and therefore stronger in
its transverse direction; and if when in a contracted state the par-
ticles of which it is composed are really brought nearer  to each
other, then it should be doubly strong, viz., in proportion to its in-
                               25 
278          HUNTER ON THE ANIMAL CECONOMY.
 creased size and closer approximation of its particles.   But as the
 state of a muscle in contraction is totally different from its natural
 state, or that state  which constitutes  the  natural structure of a
 muscle, no comparative experiments can be made which can explain
 anything.                                             .
   It is  evident from  observation, that  in the construction  ot  a
 muscular fibre it was not necessary that they should be all of equal
 density, for we find some fibres denser than others. We find  this
 difference in the different tribes of animals; in some the fibres are
 extremely soft, while in others they are very firm.
   The firm fibre is found in the more perfect  animals, called quad-
 rupeds, especially when full-grown; and  this  difference of  density
 of muscular fibres would appear to be in  a pretty regular gradation
 from the most imperfect to the most perfect, from  the muscles of
 the medusa to those of the full-grown quadruped.
  We may also observe that the first  rudiments of every animal
 are extremely soft, and even the rudiments  of the more perfect are
 similar to the full-grown imperfect, and as they advance in  growth
 they become firmer and firmer in texture.
  It may likewise be observed that there  is  a very  considerable
 difference in  the densities of the muscles  in some of those animals
 that are of distinct sexes, the male (probably in most) having by
 much the densest muscles: and  the muscles  of the same animal,
 whether perfect or imperfect, are not of equal densities, some being
 denser than  others.
  This arises from two  causes,—one natural,  growing up with the
 animal, the other acquired by frequent action.
  This difference in density of the muscular fibres  in different ani-
 mals, and in the  same animal at different  ages, in different sexes of
 the same species, and even in the same sex,  also the increased density
 arising from action, must answer some material purpose, and, from
 every observation, it would appear to produce strength or power"
 in the contraction of the muscular fibre.
  From  every circumstance  attending muscular contraction, it is
 obvious that those muscles employed in, or intended for the strongest
 actions, are the firmest in texture of any animal body, at least from
 many circumstances  it is natural to suppose so ; that they are the
 strongest would appear from the situation  in which the firmest mus-
 cles are placed, for where the strongest  actions are found in the
 living body, there we find the  firmest muscles after death.
  There are two causes for this situation of the firm  or  strong
 muscles ; the first is an  original or natural one, a  principle in the
 animal ceconomy, depending upon the natural growth of the  animal
 as much us the formation of a leg or any  other part.  The second
 is action.
  If we  take a general view of the first or natural  cause, we shall
 see from these general  observations where  we are to expect  the
strongest, and of course the hardest, muscles in any given animal
whose mode of action is known. 
         CROONIAN LECTURES ON MUSCULAR MOTION.      279

  In animals which  have progressive motion  it will generally, if
not always, be found that this  action will be one of their greatest,
because  the parts  intended for progressive  motion bear a small
proportion to the whole animal, which they are obliged to move;
whereas, every other part has  its peculiar muscle, and the muscle
is only obliged to move that one part, which is small in proportion
to the others.
  Another action which many animals are endowed with, and which
requires very considerable  strength, is fighting; this is an action
which always requires great powers in the muscles, because it  is
an action  in a part which is to overcome the whole  strength and
weight of its antagonist, which is more than the natural weight of
the same muscle, or the  resistance of the same muscle, or the resist-
ance of any muscle in the same body.                    *
  Another  partial  cause  of  strength  in  some animals is for
catching their prey, which  is to  overcome  a resistance consider-
ably beyond the  motion of the part itself which is to perform the
action.
  If such parts of animals as  are  adapted for progressive motion,
for  fighting, or for catching prey, require the greatest strength in
the muscle adapted for such purposes, and if we find that such parts
as are endowed  with the firmest  muscles are strongest, where all
those purposes are united in the same part  in any one animal, we
must find there the greatest strength,  and of course the firmest of
all the muscles in the body, especially if every one of these actions
is considerable or violent.
  Thus, then, we find the muscles in  the arm of a lion where all
these three purposes  are performed, are extremely firm in texture,
and we must suppose are also exceedingly strong.  The muscles of
the thigh of a fighting-cock are employed in fighting and  progres-
sive motion, and are extremely firm.
  The muscle which has the greatest resistance in an animal body
to overcome is the heart, especially in quadrupeds, and this is perhaps
the firmest in the body, being even firmer than those which  have the
above-mentioned resistances to overcome;  but the firmness of  this
muscle may in some measure arise from its action, which  I called
the second cause of firmness.
  Some muscles in the  more perfect animals are much firmer than
others in the same animal: such is the muscle which draws the
snail into its shell, and  retains  it  there against almost any power
that can be applied;  also the muscle which shuts the two  shells of
the bivalve is very firm in its texture, and we know that itis exceed-
ingly strong.
  A difference is sometimes found in  firmness between the muscles
of the  male and  female; this, however, is not universal, not taking
place in fish; but in all  animals where the males have a disposition
to fi^ht and the females not, or at least in a less degree, I believe
the  muscles of the male are much firmer than those of the female,
and this in proportion as their disposition for fighting is greater j 
280          HUNTER ON THE ANIMAL (ECONOMY.
 therefore in beasts of prey, where the disposition to fight is nearly
 equal in the male and female, the difference in strength is not so
 remarkable as in many other animals, there being very little differ-
 ence between  a male and female  cat, a dog  and bitch, a male
 and female hawk, &c; but the muscles appropriated for catching
 prey, and also for fighting, are much firmer than the other muscles
 in the same body allotted for common purposes, and according to
 our reasoning they must be much stronger.
   We find, however, in animals which do not catch  prey, and
 where the male has a strong  tendency to fight with the males of
 its  own species, while the female has this  disposition very little, if
 at all, that there is a very considerable  difference  in the strength
 of the same parts in the male and female while afive, and a similar
 difference in the firmness of their muscles after death.
   There is a considerable difference  between the muscles of a bull
 and cow, and also between those of a cock and hen.
   Besides  the general strength of the muscles of those males who
 fight, as they have parts which are intended for this purpose,  we
 find that the muscles of those parts far exceed all their other mus-
 cles in firmness; as  the muscles in  the neck of the bull, and  the
 legs of the  cock, far exceed in  firmness all the other muscles in  the
 body, and exceed, therefore, in a much greater degree the muscles
 of the female.
  We may also observe, that all those  muscles in the male imme-
 diately employed in fighting, although not intended for  this action
 alone, having other actions which are common to the female,  be-
 sides  being firmer than those of the female, are  very considerably
 increased in  size; thus the muscles of the neck of the bull, and of
the stone horse, those of the legs of the cock, &c, are much thicker
 and larger  than in the female.
  The second cause of firmness in a muscle, and which contributes
to its strength, is action, or what is commonly called exercise, and
which has  in general been  considered  as the principal cause  of
strength, size, and firmness.
  This may be called accidental, as  it is not confined to any order
 of animals, or any one set of muscles ; it may, however, be observ-
ed, that  the muscles employed in progressive motion  and the pur-
poses above-mentioned, are more subject to  this accidental cause .
of firmness than any other in the body, both from the natural ac-
tions of the body, and also, being naturally firm and strong, from
 more readily being employed in violent actions.
  Thus  we find the  muscles employed in progressive motion are
much firmer than any other muscles in the same animal, both from
nature and action, except in those in the fighting males (who  do
not catch their food by violence), which are employed for that pur-
pose, as in  the neck of the bull.
  The heart of all animals partakes  strongly of the two causes  of
firmness, and is perhaps the firmest muscle in the body   This firm-
ness in the heart is very early in life, for in the  small embryo the 
          CROONIAN LECTURES ON  MUSCULAR MOTION.      281

 heart is a pretty firm manageable part, while every other muscular
 part of the animal is as tender as jelly.
   Constant action not only  gives firmness to muscles, but increase
 of size.
   The epicure is no less  sensible of the effects of these causes of
 firmness  than the physiologist,  and  therefore prefers the  inactive
 parts; and the leg of the woodcock, the breast of the partridge,
 pheasant, turkey, &c, are held in high estimation.  He even takes
 pains  to diminish  the  effects  which arise from exercise,  &c, by
 feeding animals in such a way  as to prevent them taking place.—
 Upon  this principle house  lamb, veal, &c, are made tender.  How
 delicious  to the sensualist must  the flesh of the sloth be, if the ac-
 count  of its motion being  far exceeded by a snail is true!
   From the above account  it must appear that  muscles, in propor-
 tion as they  are firm in texture, will be strong in action;  it is at
 least demonstrable in the muscles of the same animal whose texture
 is different, and in similar  muscles in the male and female of the
 same species, and we may reasonably suppose that it will hold good
 in different species; and therefore, when we find the muscles very
 firm in any one species, we may conclude that this species is stronger
 than any other species in which the muscles are tender and soft.
   This firmness in a muscular fibre we may suppose to arise from
 the density of its component parts, or  those parts being closer to-
 gether, the uniting  medium being less in quantity; this, however, it
 is perhaps impossible to determine exactly.
   That this idea  may be better understood, I shall suppose  that a
 part composed of dense parts (aggregated) at a given distance, will
 be firmer than a part composed  of less firm  parts at the same dis-
 tance ; and it is plain that a part composed of any given substance
 will  be dense in proportion as the parts of that  substance are near
 to each other.
   It may probably be  similar to  iron  and  steel; in  the iron the
 parts or" crystals which compose the mass are large,  and  perhaps
 not regular.  In the steel they are small, and probably more regular
 in their figure, by which means they can  adapt  themselves  better
 to each other, and still more  so if tempered, according to the degree
 of temper, so that their crystals shall become still smaller, and of
 course the whole becomes harder.
   To ascertain whether the firm  muscles really contained more
 matter, and were therefore specifically heavier than the soft, I made
several experiments  upon muscles of different densities.  The ex-
periments were made upon the same muscle of two animals  of the
same species whose muscles are of different densities, viz., the mus-
cles  of the neck of the ox  and bull.*
   Nine ounces and a half of muscle from  a bull's neck,  and the

  * My reason for choosing those muscles in preference to others was, that they
admit a greater degree of difference in firmness, and that they have no tendons
intermixed, so as to give density from that cause.
                              25* 
282
HUNTER ON THE ANIMAL CECONOMY.
same quantity from  that of an ox, were weighed  in water, when
the bull's was thirty-one grains heavier, which is about TTS-tn-*
  From this experiment it appears that there is some difference in
weight between a firm muscle and one that is naturally soft or lax,
although not great, not even so much as one might  at first imagine,
at least not so much as the apparent difference in density.
  As it appears, from  the above observations, that with the same
given size the firmer muscles are the strongest, it becomes a ques-
tion why every  muscle in the  bodies of the more perfect animals,
and in the young of such animals, as also the muscles of the more
simple animals in general, should not  all have been of this texture,
which constitutes the greatest power of contraction 1  This is per-
haps not yet to  be fully answered.   It certainly  would have ren-
dered many parts of the more  perfect animals much smaller than
what  they now  are,  and  would have  had  the same effect upon the
whole body of the young of the more perfect animals, as also of
the  more  simple animals universally; we must, however, suppose
that  it would  have been  attended  with  some  inconveniences,
although  at present what these inconveniences would have been
may not be perfectly understood.
      26.  THE USE  OF THE OBLIQUE MUSCLES.

  Muscles are the active parts in an animal body, producing dif-
ferent effects, according to the circumstances  in which they are
placed;  and the  greater number of parts  requiring a variety of
motions, it  became necessary to  have a variety of muscles suited
to such motions.
  The function of a muscle depends on the contraction of its fibres;
and the most general effect produced by this contraction is to move
some  one  part  of the body upon another.   But we  may observe,
that when  motion in a part is performed by one  set of muscles,
there  are  other muscles employed in regulating that motion,  as in
most joints; and in a whole part, destined to a variety of motions,
and composed of smaller parts, intended likewise to have their dis-
tinct  motions,  we find muscles  appropriated for  the purpose of
keeping some of those parts fixed in a particular position, while the
whole part is  to be moved  by other muscles, according to the
nature of  the action to be performed.  This will, perhaps, be best
illustrated  by attending  to what takes place in the eye, considering
it as part of the head.
  The eye being an organ of sense, which is  to receive impressions
from without, it was necessary it should be able to give its motions
* [See note, p. 26C] 
THE USE  OF THE OBLIQUE MUSCLES.         283
that kind of direction as would permit its being impressed by objects
whether  at  rest or in motion, or  moving  from object to object;
and it was also necessary that there should be a power capable of
keeping the  eye fixed upon an object, when our body or head was
in motion.
   For the better  understanding this action  of pointing the  eye
towards  objects under  the various circumstances of vision, it will
be necessary to mention  that the  eye  is  furnished with muscles,
some of which, in the  quadruped, bird, amphibia, and fishes, are
called straight, from their being placed in the direction of or parallel
to  the axis of  the eye; and two, I believe,  have always  been
named oblique.  Of the  straight, some animals  have more  than
others.   There are four straight muscles common to most animals;
and those which have more  have  the additional muscles inserted
immediately in the eyeball on its  posterior surface, and surround-
ing the optic nerve.   The four straight muscles, which are common
to all quadrupeds pass further forwards, and are rather inserted
towards the anterior surface of the eye.
   For vision at large it was not only necessary that the eye should
be capable of moving from object  to object,  or of following  any
object in motion, but also necessary that there should be a power
to keep it fixed on any one  object to which the  mind  might be
attentive ; therefore the muscles are formed  so as not only  to be
able to move the eye from object to object, but likewise to keep its
point of vision fixed upon any particular  one, while the  eye  is
moving progressively with the head or body. This is the use of these
muscles, when the parts  from whence  they  arise are kept  fixed
respecting the objects the eye is pointed to ; but it is often neces-
sary, while the eye is fixed upon a particular object, that the  eye-
ball and the head in which  it is fixed should shift their situation
respecting that object;  and  this  would alter the direction of the
eye, if the muscles had not the power of taking up an action  that
produces a  contrary effect, that is, keeping the point of insertion of
the muscles as the fixed point, by  causing  their fibres  to contract
 according as the origins  of the muscles vary their position respect-
ing the object.  From this mechanism we find these  three modes
 of action produced :  first, the eye  moving from one fixed object to
 another; then the eye moving  along with an object in motion; and, last,
 the eye keeping its axis to an object, although the whole eye, and the
 head, of which it makes  a  part, are in motion.   From  either  of
 these motions  taking place  singly, or being  combined, the eye is
 always  kept towards its object.   In the two  first  modes of action
 the origins of the muscles are fixed points respecting the  object;
 and, in the last, the object becomes as it were the centre  of motion;
 or fixed point, commanding  the direction of the actions of  the eye,
 as the north commands the  direction of the  needle, let the box in
 which it is placed be moved in what direction it  may.  These two
 first modes of action are performed by the straight  muscles ; for
 the head being a fixed point, they are  capable of moving the eye 
284
HUNTER ON THE ANIMAL CECONOMY.
up and down, from right to left, with all the intermediate motions,
which taken together, constitute a  circular  movement;  or, when
the eye is to become the fixed point, then the head itself performs
the circular movement.  Thence appears the necessity why the
object, the axis of the eye, and the  point of sensation,  should all
three be in the same straight line.  But  this does  not take place in
all movements of that whole of which  the eye makes a  part; for
besides those which we have  already taken notice of, the head is
capable of a motion from shoulder to shoulder, the axis of which is
through the axis of the two eyes, from  the  fore to the  back  part.
It should be here observed, that for  distinct vision the object must
be fixed as  respecting the  pupil of the eye, and  not  in  the  least
allowed to move over its  surface.*   To prevent  any progressive
motion of the  object over the  retina of the  eye, either from the mo-
tion  of the object itself, or of the head  in some  of the motions of
that  part, the  straight  muscles are provided as has been explained ;
but the effects which would arise from  some other  motion of the
head, as from shoulder to shoulder, cannot  be  corrected by the
action of  the straight  muscles, therefore the oblique  muscles are
provided.   Thus when we look at an object, and at the same time
move  our  head  to either  shoulder, it is moving in the  arch of a
circle whose centre is the  neck ;  and of course the eyes would have
the same quantity of  motion on this axis if the  oblique muscles did
not fix them upon the object.   When the  head is moved towards
the right shoulder the superior oblique muscle of the right side  acts
and  keeps the right eye  fixed  on the object; arid  a similar effect is
produced upon the left eye by the action of its inferior oblique mus-
cle:  when the head moves in a contrary direction the other oblique
muscles produce the same effect.   This motion of the head  may,
however, be to a greater extent than can  be  counteracted by the
action of the oblique muscles.   Thus, for instance, while the head
is on the left shoulder  the eyes may be  fixed upon an  object, and
continue looking at it while the head is  moved to the right shoulder,
which sweep of the head produces a greater effect  upon the  eye-
balls than can be counteracted by the action of the oblique muscles;
and  in this case we find that the oblique muscles let  go  the  eye,
so that it  immediately returns into its natural situation in the orbit.
Whether this  is performed by the natural elasticity of the parts, or

  *  Optical writers seem to have been entirely ignorant of this ; for they not only
suppose distinct vision compatible with the object having a motion over the
different parts of the retina, but even explain the effects which would be produced
by it on the mind of the observer.  Keill makes the following observation :
  » Since optics teach us that every body which is visible has by means of the
rays  which proceed from that object its image painted on the bottom of the eye
or retina, it follows that  those objects will seern  to be moved whose images
are moved on the retina, that is, which pass over successively the different parts
of the retina whilst the eye is  supposed to be  at rest; but those objects will be
looked upon as being at rest whose images always occupy the same part of the
retina, that is, when the motion of those images are not perceived in the bottom
of the eye."—Keill's Introduction to Natural Philosophy, p. 79. 
     ON THE COLOUR OF THE PIGMENTUM OF THE EYE.   285

whether the antagonist oblique muscles take up the action and rein-
state the eye, I do not know.  If the head  still continues  its mo-
tion in the same direction, then the same oblique  muscles begin to
act anew, and go on  acting, so as  to keep  the  eyes fixed  on the
object.  As this motion of the head seldom  takes place uncombined
with its other motions, some of the straight and  oblique  muscles
will be employed at the same time, according as  the motions are
more or less compounded.
 21.  ON  THE COLOUR OF THE PIGMENTUM OF THE
              EYE  IN DIFFERENT ANIMALS.

   In the eyes of all animals which I have examined there is a sub-
 stance approaching to the nature and  appearance of a membrane,
 called the pigmentum, which lines the choroid coat, and is some-
 what similar to the rete mucosum which lies  under the cuticle of
 the human body; and there is also some of the  same kind of sub-
 stance diffused through the cellular membrane which unites the
 choroid with the sclerotic coat.  My intention at present is only to
 communicate the observations I have made  on  this subject and its
 use, confining myself to the consideration of that kind of it which
 lines the tunica choroides of  the class Mammalia, and of birds; in
 doing which I shall also take occasion to speak of the difference of
 colour occurring in animals of the same species.  Although an ac-
 curate examination of the appearances of a similar substance in the
 eyes of some fishes might illustrate the subject, we cannot avail our-
 selves of that, as  from not  being sufficiently acquainted  with the
 effects of light upon the eyes  of that class of animals.
   The propagation or continuance of animals in their distinct classes
 is an established law  of Nature,  and in a general way is preserved
 with a tolerable degree of uniformity; but in the individuals of each
 species varieties are every day produced in colour, shape, size, and
 disposition.   Some of these changes are permanent  with respect to
 the propagation of the animal, becoming so far  a part of its nature
 as to  be continued in  its offspring.
   Animals living in a free  and natural state are subject to few
 deviations from their  specific character; but nature is less uniform
 in its operations when influenced by culture.*   Considerable varie-
 ties are produced under such circumstances, of which the most fre-

  * From the variations produced by culture it would appear that the animal is
 so susceptible of impression as to vary Nature's actions ; and this is even carried
into propagation. Whether this takes place at the very first union of the principles
of the two parents, so as  to derive its existence from both ; or whether it takes
its formation from the mother, after the first formation of the embryo, are perhaps
not easily determined. 
286          HUNTER ON THE ANIMAL CECONOMY.

quent are changes  in  the  colour.   These changes are  always, I
believe, from the dark to the lighter tints, and  the alteration very
gradual in certain species, requiring in the canary-bird several gem-
rations; while in the crow, mouse, &c, it is completed in one.  But
this change is not always to white, though still approaching nearer
to it in the young  than in the parent, being sometimes to dun, at
others to spotted, of all the various shades between the two extremes.
This alteration in colour being constantly from dark to lighter, may
we not  reasonably infer that in all animals subject to such variation
the darkest of the species should be reckoned nearest to the original;
and that where there  are  specimens of a particular kind, entirely
black, the whole have been  originallv black ?   Without this suppo-
sition it will be impossible, on the  principle I have stated, to account
for individuals of any class being  black.  Every such variety may
be  considered  as  arising  in the  cultivated state  of  animals;  but
whether, if left to themselves, they would in time resume their ori-
ginal appearance, I do not know.*
  The colour of the  pigmentum of the eye always corresponds, 1
believe, with that of the hair and skin, especially  if the  animal be
only of one colour, but is principally determined by the hair ; and
the most general colour is a very dark brown, approaching to black,
from whence it had  the name, nigrum pigmentum.f  The colour
differs in  different classes  of  animals, often  in  the same class,
and even  in  the same  species.   In the human  it is  most com-
monly dark, in the ferret  kind always light, and  its difference of
colour in the same  species is evident from the variety observable in
the eyes of different people.  There is e\ 1a difference of colour
in the same eye in many classes of animals,  in  all of the cat and
dog kind, and perhaps in most part of the granivorous.   In some it
is partly black, and partly of the appearance of polished silver ; and
in many classes the variation from dark is of  two colours: for in
the cow, in sheep, deer, horses, and  I believe in all animals feeding
on grass, there are  in the same eye certain portions of it white, and
others of a fine green colour.  The difference in colour of this pig-
mentum in the eyes of different animals  of the same species is very
remarkable : in  the human  species  it is of  all the  different shades
between  black and almost  white, and the same variety is seen in
rabbits, mice, crows, blackbirds, &c, but in these it is of one colour
only in  the same eye.  Every species  is, perhaps, subject to such
variations; and  some of these are so extraordinary as with pro-
priety to be denominated monstrous.J
  *  In vegetables, I believe, it invariably holds good that, however improved by
culture, if neglected, they soon degenerate into their first state.
  j As the colour of this membrane corresponds with the colour of the skin and
hair of the person, it is  probable that the people among whom it first got the name
were dark.
  X Perhaps the word monstrous  is too strong, or not exactly just.  It certainly
may be laid down as one of the principles or laws of Nature to deviate under
certain circumstances.  It may also be observed, that it is neither necessary, nor
does it follow that all deviations from the original must be a falling off; it appears 
       ON THE COLOUR OF THE PIGMENTUM OF THE EYE.   287

   The variation in the colour of the pigmentum indifferent species
 of animals  seems  to depend on  a fixed law of Nature;  but the
 varieties which are met with in the same  species are much less
 constant, being  merely different shades approaching  to black or
 white.   But the extraordinary circumstance is its being sometimes
 unusually lighter or darker in individuals of the same species; and
 this difference not  seldom starting  up  in the young without any
 hereditary principle to account for it.
   The human species is  a striking example of the colour of the
 pigmentum  corresponding with that of the skin and hair; and though
 the skin and hair of one person differs very considerably from the skin
 and hair of another, yet it is not  in so  great a degree as in many
 animals.  There are cattle perfectly white, white sheep, white dogs,
 white cats and rabbits ; but there are few of the human species that
 we can say are perfectly white.   They rather pass from the black
 into the brown, red, and even light yellow ; and we find this pigmen-
 tum, although only of one colour, varying through all the different
 corresponding  shades.   In the  African negro, the  blackness of
 whose hair and skin are  great distinguishing characteristics, this
 pigmentum  is also very black.   In  the mulatto, who  has  not the
 skin so dark as the African, but the hair nearly as black, this pig-
 mentum is of a shade not quite so deep ; yet still it does not approach
 so near to the middle tint as the skin, rather  following the colour of
 the hair.  In people of a  swarthy complexion, as Indians, Turks,
 Tartars, Moors, &c, we find the hair always of a jet black, and this
 substance of a much darker brown than in those that are fair.  In
 those of very dark complexions, and having very black hair, although
 descended from fair parents, the same thing holds good.  There are
 few species of animals, or even individuals of a species, whose bodies
 are only of  one colour.   Crows and some others, are  exceptions;
 but the greatest number are of two or more,  being variously spotted
 or streaked  either with different colours,  or with shades of the same.
 Many species are constantly lighter in some parts of the body than
 in others; and, with a few exceptions, animals are generally lighter,
 as  to colour, on the lower, or what  may be  called the  foreparts,
 than on  the upper or backparts.  The fair man  or woman may
 strictly be considered as a  spotted or variegated  animal.  In many
 persons the  hair of the head, eyebrows, eyelashes, beard, and hair
 on the pubes, all vary in  colour.  The hair of the three first  may be
 called foetal, and are oftener  all of the same than  of a different
 colour; the  two last are  to  be  considered  as adult hair, and are
commonly alike in colour, which yet frequently varies from that of
the foetus, which last is  more liable to change  its  colour than the
other ;  and the change is generally that of growing darker, especially
on the head and the eyelashes.*   This  difference  in the  colour of
just the contrary, therefore we may suppose that Nature is improving her works,
or at least has established the principle of improvement in the body as well as
in the mind.
  * The hair growing gray is not in the least to the present purpose. 
288
HUNTER ON THE ANIMAL CECONOMY.
the hair on different parts of the body is not so observable in those
nations who are dark or swarthy, as in people inhabiting many of
the northern climates.
  In animals which are variegated let us observe the colour of this
pigmentum, and we shall find it regulated by some general principle,
and corresponding with the colour of the eyelashes.  The magpie,
for instance, is nearly one-third, or fourth part white ;  and the two
colours, if blended, would make the compound gray;  but the eye-
lashes being black the pigmentum is black also.   We sometimes
meet with people whose skin and  hair are very white and yet the
iris is dark, which is a sign of a dark  pigmentum ; but if we examine
more  carefully we shall also  find  that the  eyelashes  are  dark,
although the eyebrows may be the colour of the common hair.
  As the colour of the iris in the human species is probably a pre-
sumptive, though not  a certain sign of the colour of this pigmentum,
we may be led to suppose that in those who have the iris in one eye
different from that of the other, this substance will likewise  differ;
but this I cannot determine, never having examined the eyes of any
person with  such a peculiarity.  It  is not an uncommon circum-
stance in some species of animals,  the Angola cat seldom having
the colour of the iris  the same in both eyes.
  In people  remarkably fair, whether they are  of a race that is
naturally so, or what  may be called monstrous in respect to colour,
as white ^Ethiopians, still we find this pigmentum following  the
colour of the skin and hair, being  in some of a light brown, and in
others almost white,  according to  the  colour  of the hair in such
people.
  All foals are of the same colour, and whatever  that  may be, as
they grow older it generally becomes lighter,  therefore the pigmen-
tum  in  them is  almost  always of  the same colour, and does not
seem to change with the hair.  This change, however, is only in
the hair, and  not in the  skin, the  skin of a  white or gray  horse
being as dark as the  skin of a  black one: yet there is a cream-
coloured breed which has the skin of the same colour, whose foals
are also of a cream-colour; and by inspecting the parts not covered
with hair, such  as  the  mouth, anus, sheath, &c, these, and the
pigmentum of the eyes of such horses, are  found of a cream-colour
likewise.
  In the pigmentum  of the rabbit  kind there are all the  degrees of
dark and light, corresponding with the colour  of the hair; yet there
seem to be exceptions to this rule  in some white rabbits with black
eyes, and therefore with black  pigmentum  ; but in  all such there is
either a circle of black hair surrounding the eve or the  eyelashes,
and the skin forming the edge of  the lid is also  black.   In  many-
white cattle this is also observable; and in that breed of dogs called.
Danes some have the hair surrounding one  eye  black, while the
hair surrounding the other is white; and the iris of the one is often
lighter than  that of the other.   This circumstance, of the iris of one
eye being lighter in colour than that of the other, is  a common thing 
      ON THE COLOUR OF THE PIGMENTUM OF THE EYE.   289

in the  human species;  and  sometimes only one half oftheirisis
light, without any difference in the colour of the eyelash or eye-
brow.   Whether this difference in the colour of the iris of the two
eyes in the same animal is owing to the pigmentum  being different
in colour, I do not know, although I rather suspect it is something
similar to the white iris in horses, which makes them what is called
wall-eyed.
   The  variation of colour appears most remarkable when a  white
starts  up, either where  the whole species" is black, as in the  crow
or blackbird, or  where only a certain part of the species is  black
(but permanently so), as a white child borne of black parents; and
a perfectly white child, whose hair is white, and who has the pig-
mentum also white, though born of parents who are fair, should  as
much  be considered  as a play of Nature as the others.   All  these
lusus naturae, such as the white  negro, the pure white child of fair
parents,  the white crow, the white blackbird, white mice, &c, have
likewise a white pigmentum corresponding with the colour of the
hair, feathers, and skin.
   Besides the circumstance of animals of the same species differing
from one another in colour,  there are  some distinct species which
are, as far as we know, always of a light colour, and in them, too,
this pigmentum is white :  the animal I allude to is the ferret.
   When the pigmentum is of more than one colour in the same eye,
the lighter portion is always placed at the  bottom of the eye,  in the
shape  of a half-moon, with the circular arch upward, the straight
line or diameter passing almost  horizontally across the lower edge
of the optic nerve, so that the end of the nerve is  within this lighter
coloured part,  which makes a kind  of semicircular sweep above
it.   This shape  is peculiar to the cat, lion, dog, and most  of the
carnivorous  tribe;  in the herbivorous the upper edge being irre-
gular ;  in the seal, however, the  light part of this pigmentum is
equally  disposed all  round the optic  nerve, and is, on the whole,
broader than it is commonly found in quadrupeds.  How far  this
increase of surface is an approach towards the fish kind, in which
it is wholly of this metallic white, I will not pretend  to say, but it is
probable, as the animal is to see in the water as well as in the air,
that it may  be formed  circular, the better to correspond with the
form of the  eyelids, which open equally all around, which  seems
to  accord with what is observable in fishes, they being without
eyelids.
   The colour of the pigmentum, whether white or green, or both,
has always a bright surface, appearing like polished metal,  which
appearance  animal  substance is very  capable of taking  on,  as we
see in hair, feathers,  silk, &c.
   After having  taken notice of the various colours of this pigmen-
tum in different  animals, both where permanent and where it ap-
pears to be a play of Nature, let us next examine what effect it has
 upon  vision in  both cases, whether these  effects are similar, or if
one case illustrates the  other.
                                26 
290          HUNTER ON THE ANIMAL CECONOMY.
   It may be asserted as an undoubted  fact,  that the light which
 falls on the retina  covering  a white pigmentum has more effect
 than when it falls on the retina which  covers a dark one; which
 is known by comparing the vision of those of the same species who
 have the pigmentum wholly dark with those who have it perfectly
 white ;  and something may be learned by a similar comparison of
 animals who have  it only in different species, it being  reasonable,
 from  analogy, to suppose that some such effect is produced in the
 eye which is possessed of both.
   I shall first consider the effect produced when the white or light
 colour makes  only  part of the pigmentum.  This will lead me to
 observe, that all animals having the pigmentum diversified, though
 they are capable of bearing as much light as others, and  can see
 as perfectly when  light is  in  an equal  degree ; can likewise see
 very distinctly  when the light is much  less  than will  serve the
 purposes of animals having it wholly dark.  May we not, therefore,
 ascribe this advantage to the pigmentum  being partly white 1   One
 might be almost tempted  to suppose that such animals have a power
 of presenting  the different parts of the eye  to the light,  accord-
 ing to  the quantity of light required ; or of moving the crystalline
 humour higher or lower : but we are at  present unacquainted with
 any power in the eye by which these actions can be performed.
  We may observe, that when a cat or dog looks at us in the twi-
light the whole pupil is enlarged and illuminated, but in a full light
there is  no such appearance.   It is plain there must be a reflexion
of light  from the bottom of the eye to  produce the above effect,
 especially as the light reflected  is always of  the colour of the pig-
 mentum in such animals, which in the cow is  of a light green.
  I shall secondly consider those animals which have the whole
pigmentum of a white colour, whether it is accidental  or  natural,
and that see much  better in the dark, or with less light than those
in which it is of a dark colour ; of the first of these I shall take my
instance from  the human species;  of the  second the  ferret will
 serve as an example.
  Those of the human species who have the pigmentum of a  light
 colour  see much better with a less degree of light than those who
 have it dark ; and this in proportion to their fairness ; for when the
 hair is quite  white they cannot see at all in open day without knit-
 ting their eyebrows  and  keeping the eyelids almost shut.  In many
 of these instances there is an universal glare of light from the pupil,
 tinged with  a  shade of  red,  which  colour, most probably, arises
 from the blood in the vessels of the choroid coat.  I have "likewise
 observed that the pigmentum  is thinnest when it is  light, so that
 some of the light which  is reflected from the point of vision would
 seem to  be thrown all over the inner surface of the eye, which being
 white, or rather a reddish-white, the light appears to be  again re-
 flected from side to  side.*  This seemed to be the case in a boy at
  * How far this is really the case  I do not absolutely say ; for whatever light
 comes through the pupil must be reflected from the point of vision ; but I imagined
 I saw the light passing  through the substance of the iris. 
      ON THE COLOUR OF THE PIGMENTUM OF THE EYE.   291

Shepperton, when about three years of age, of whom I have a por-
trait, to show that appearance.   He is now about thirteen years of
age:* the common light of the day is still  too much for him;  the
twilight is less offensive.   When in a room he turns his eyes from
the window, and when  made to expose his face to the  light, or
when out in the open air, he knits his eyebrows, half shuts his eye-
lids, and bends  his head forwards, or a little  down; yet the light
appears to  be less obnoxious  to him  now  than formerly, probably
from habit.  Such persons appear to be nearer-sighted than people
in common, but I  apprehend that appearance  to arise from  the
position into which they throw the eyelids and eyebrows, which not
only in a great degree excludes the light, making the object faint in
proportion  to the contraction of  the pupil  and shade made by the
eyelids  and eyebrows, but  at the same  time fits  the  eye to see
near objects; for if we nearly close our eyelids and knit our eye-
brows we can see a small object much nearer than  if we  did not
perform such actions, and it  will make above a foot difference in
the focal distance of the eye.
   In many rabbits who  have white eyelashes, and in white  mice,
the pigmentum is entirely white, which is likewise observable in  a
certain distinct species of animals, the ferret, which we have ad-
duced as an example of the  pigmentum being naturally white; for
these  animals being intended to see in the  dark, and their  mode of
life not exposing them to the light, they are liable to be affected by
strong light to a greater degree than many others.
   If it is allowed as probable that in animals having the pigmentum
diversified  the  object to  be viewed  is thrown upon  the  lighter
coloured portion, how does it happen that  such are able to bear the
light better than those who  have the pigmentum altogether of  a
light colour ?  Perhaps it is not the  illuminated object itself that is
offensive to the retina, but that diffusion of light in the one kind of
eye which does not happen in the other.
   Having stated the facts, and the general effect arising from the
diversified  pigmentum, let us consider  the manner  in which it is
brought about, that such animals see better with little light than
those which have the pigmentum wholly black.
   Let us then suppose the retina to be the  organ of sight,  and that
by the rays which fall upon it being properly refracted  it  gives or
conveys to the mind an idea of a distinct object, corresponding with
the sensation of touch.   This is the most common and simple man-
ner in which vision is performed, and is that mode which takes place
where the  pigmentum is black, or nearly so, and where the greatest
quantity of external light is required.
   The "retina, although somewhat opaque,  is yet  so  transparent as
to allow a  considerable quantity of light to pass through it.   For if
this was not the case there  could not be  those  differences  in the
appearance of  the eye which I have been describing.  The rays
which pass through, we may suppose, do or do not give  sensation
   * The period here alluded to is 1786, when the  first edition of this work was
published. 
292          HUNTER ON THE ANIMAL CECONOMY.

in their passage ; and we may also suppose that only those which
strike against the retina are the cause of sensation:  but this is not
the present inquiry; the  rays which pass through the retina  are
what I am alone to consider, which falling upon the pigmentum are
there disposed of according  to the reflecting  powTers of that sub-
stance.  If the pigmentum is black the rays will then be absorbed,
and entirely  lost, therefore in such eyes vision  can receive no
assistance from it, and consequently a considerable quantity of light
is required to produce distinct vision ; but in those who have some
part of this pigmentum white, we find that the rays of light which
pass through the retina are reflected back again; and in this case it
is not unnatural to suppose that the reflected rays, in their passage
back, will strike against the retina, and increase the power of vision.
It is evident that a  considerable portion passes forwards through the
retina,  which, I suspect, is partly lost on the  inner  surface of the
lateral  and forepart of the eye, where the pigmentum is black, while
the remainder passing through the pupil is  again thrown  on the
object looked  at.  The next thing to be considered is, whether the
shape of the eye is such as will throw the rays, which passed through
the retina, back upon that membrane, in the same or nearly in the
same place as  that  through which they originally came.   The  eye
being a sphere, or approaching to that figure, makes it probable;
but whether the curve is such as will reflect the rays exactly in the
same direction is not so easily determined.  If the curve be a true
one, then the rays that are not obstructed in their return  by the
retina must pass forwards through the pupil, and, being refracted in
their passage through the  crystalline humour, will be sent out of the
eye in  the same lines in which they entered, and be thrown on the
very object from whence they came; which seems to be in a great
measure  the  case, if we may judge by the degree of illumination
in the cat's eyes.  If the rays reflected from the light part of the
pigmentum should not, in  their return, strike  exactly on the same
points  in the  retina, through which they first  passed, yet if they'
are thrown nearly on the  same place it will  be  sufficient, for we
know that our sensations are not capable of conveying to the mind
mathematical  exactness.   And  the  same circumstance will  be a
sufficient answer, should it be objected that  the  time  lost in the
passing and repassing of the rays  may prevent distinct vision ; for
it is known that if an illumined body is made  to move quickly in a
circle,  it will appear to the eye a circle of fire.
28. SOME FACTS RELATIVE TO THE LATE MR.  JOHN
   HUNTER'S  PREPARATION  FOR  THE CROONIAN
   LECTURE.
                BY EVERARD HOME, ESQ.r F. R. S.
                     [Read November 14,1793.]
   Mr. Hunter having announced  to the Royal Society that  he
would make the structure of the crystalline  humour of the eye the 
          PREPARATION FOR THE  CROONIAN LECTURE.       293

 subject of the Croonian lecture for the present year, and having, un-
 fortunately for science, died before his observations on that subject
 were  rendered complete, I feel it a duty I owe to his memory as
 well as to the Society, to state the facts  respecting this humour
 with which he had acquainted me; and  shall subjoin  an unfinished
 letter  from Mr. Hunter to Sir Joseph Banks on the same subject.
   It is now many years that Mr. Hunter has had an idea that the
 crystalline humour was enabled by its own internal actions to adjust
 itself,  so  as to adapt the eye to different«distances; and when the
 Tcenia hydatigena* first came under his observation as a living ani-
 mal, he was surprised to see the quantity of contraction that took
 place  in a membrane devoid of muscular fibres, but  made use of
 the  facts in his investigation of  the structure of the crystalline hu-
 mour  of the eye.
   Some time after this, having occasion to dissect the eye of the
 cuttle-fish, which he had frequently done before, but not with exact-
 ly the same view, he discovered in the crystalline humour a struc-
 ture which corresponded with the idea he had formed of its actions
 in the human eye.   He found it composed of laminae, whose ap-
 pearance was evidently fibrous for some depth from the external
 surface ;  but becoming less and less distinct, till at last this fibrous
 appearance was entirely lost, and the middle, or central part of the
 humour, was compact and transparent, without any visible  laminae.
 From this structure it would appear that  in the eye of the cuttle-fish
 the exterior parts of the humour are fibrous, the interior parts not;
 so that the central parts is a nucleus round which the fibrous cover-
 ings are placed.  The preparations which demonstrate these facts
 will be laid before the Society.f
   As  the structure  of the crystalline humour in the cuttle-fish dik
 fers in nothing from that of the  same humour in other animals but
 in the  distinctness of the fibrous appearance, Mr. Hunter  was led
 to consider that the exterior  part in all of them was similar, although
 no appearance of fibres could be demonstrated.
   What I have here explained I was acquainted with at the time I
 had  the honour of giving  the Croonian lecture,  in  which I  ex-
 amined the different structures endowed  with muscular action, and
 was desirous that Mr. Hunter would, either of himself or through
 me,  communicate  these  observations to  the Society; but this he
 declined doing till  he had ascertained by experiment  whether any
 muscular  effect was really  produced ;  and the hope  of being
 assisted by Mr. Ramsden made  him, from  time  to time, put off
 making his experiments.
   In the course of this season he  began his experiments, which
 were founded upon the analogy  that ought  to  exist between  this

  * [The hydatid commonly found in the abdominal cavity of the sheep,—Cysti-
 cercus tenuicollis, Rudolphi.]
  X [The Hunterian preparations demonstrating the peculiarities of the eye
of the cuttle-fish are not fewer  than  twenty.   See Physiological  Catalogue,
vol.iii.,  p. 140.}
                                  26* 
294
HUNTER ON THE ANIMAL CECONOMY.
humour, if muscular, and others of a similar  structure, which led
him to expect that they would be acted upon  by the same stimuli:
and having found that a  certain degree of heat, applied through
the medium of water, will  excite muscular  action after almost
every other stimulus had failed, it was proposed to apply this to the
crystalline humour, and ascertain its effects.
  The crystalline humour taken from animals recently killed must
be considered as being still alive.  Such humours were  to be im-
mersed in water of different temperatures, and  placed  in  such  a
manner as to form the image of a  lucid, well-defined object, by a
proper apparatus for that purpose, so that any change of the place
of that image from the stimulating effects of the warm water upon
the humour would be readily ascertained.  These were the experi-
ments which Mr. Hunter had instituted and  begun;  but in which
he had not made sufficient progress to enable him to draw any con-
clusions.

            To  Sir Joseph Banks, from Mr. Hunter.

     " Sir,
   " When I did  myself the honour of giving in my claim to the dis-
covery of the crystalline  humour being muscular, and proposed to
make it the subject of the Croonian lecture, I did not foresee that
anything  could prevent me  from fulfilling my promise;  but since
that time, what  with my state of health, which does not allow me
to be very active, the hurry of official business on account of the
war, and my brother-in-law, Mr.  Home,  being employed on  the
medical staff, I have not had the  power  of  repeating  my experi-
ments, and drawing  out, to  my satisfaction, the many conclusions
 which are the result of such a power in this humour.
   " The laws of optics are  so well understood, and the knowledge
 of the eye, when considered as  an optical  instrument, has been
 rendered so perfect, that I do not consider myself capable of making
 any addition to  it:  but still there is a  power in the eye by which it
 can adapt itself to different distances far too extensive for the simple
 mechanism of the parts to  effect.  This power writers upon  this
 subject have been at great  pains to investigate and explain.  The
 motion of the crystalline  humour forwards and  backwards was
 asserted by some to be the cause, while others supposed in the eye
 a power  to alter its  shape,  so as  to shorten  or lengthen  its axis,
 which altered the distance  between the crystalline humour and  the
 point of impression; but we should consider that a part of the eye
 is itself a refractor,  and that if its  shape be altered so as to remove
 the crystalline humour from the  point of  impression, in order to
 enable it to bring a  distant  object to its proper focus on the retina,
 this effect will be in some degree counteracted by the anterior part
 of the eye refracting more than  before, by being rendered more
 convex.  But we have, in  fact, no power  capable of producing this
 effect: for the straight muscles, so far from  appearing  to have this 
          PREPARATION FOR THE CROONIAN LECTURE.      295

power, have been even supposed to flatten the eye, and shorten its axis;
and it is very possible that the  action of these muscles is such  as
tends to both effects; but, being in opposition to each  other, the
eye retains its shape, the insertion of these muscles being much more
forwards than appears to be  necessary  for the simple  motions of
the eye.  Further, when we consider that in many  animals the
shape of the eye is unalterable, as in all  of the whale tribe, the
sclerotic coat being above  half an inch thick and composed of a
strong tendinous substance ;—that in  many fish this coat is com-
posed of cartilage ;  and in  all birds the  anterior part of it is (I be-
lieve) composed of bone ;—from all these  considerations, I saw no
power that could adapt the eye to the various distances of  which
we find it capable in the human body, unless we suppose the crys-
talline humour to be varied in  figure, which  can only be effected
by a  muscular action within itself.   With this idea strongly im-
pressed upon my mind, and finding that in many animals, when the
crystalline humour was coagulated, it had a fibrous structure like
muscles, I confess it seemed to  me to confirm it; but as this might
to others appear only conjecture, requiring some  proof, I set about
such  experiments as were best adapted for that purpose.  Knowing
that in all violent deaths the  muscles  contract, I supposed the crys-
talline humour, if muscular, would show  signs  of this effect; for
which purpose I got the eyes of bullocks  when  removed from the
sockets, the  moment the animal was knocked down, and while he
eyes  were warm the humours were removed."
   Mr. Hunter had proceeded thus far in the  account of his  experi-
ments,  when he was suddenly, and very unexpectedly, carried off;
and as he has left no notes  upon this subject,  I am unable to make
any addition to the account I have already given.
   Mr.  Hunter's laying claim to the discovery of a fibrous structure
in the  crystalline  humour, which had  been observed long before,
and described by the accurate  Leuwenhoek, may appear to  require
some explanation.   The discovery of a fibrous appearance  in that
humour appertains to Leuwenhoek; but the discovery  of  an eye
in which this structure of the crystalline humour was perfectly dis-
tinct, and in which all the circumstances of course and situation
could be determined, is due to Mr.  Hunter :* and if it should be

   * [In this investigation by Hunter of the  intimate structure of the crystalline
lens we may perceive the continuation of the series of discoveries which, com-
menced by Leuwenhoek, have, in the hands of Sir David Brewster, produced
such unexpected results, and opened  so  interesting a field for philosophical ex-
periment and teleological speculation with regard to this part of the mechanism
of the instrument of vision.
   Notwithstanding the anatomical remarks of Hunter, the observation of Professor
Blair  (Edinburgh Transactions, vol.  iii.), and the experiments of Young, Wol-
laston, Wells, and Frauenhofer, we still find, even in very recent physiological
works, a mere repetition of the  simple statement of Paley that the lens consists
of concentric layers, which gradually increase in density from the circumference
to the centre ;  and, under the influence of an  apt comparison, the principle of the
construction of the lens is asserted  to be the same as that of the compound or
achromatic object-glass, and the invention of Dollond to be a  repetition, though 
296            HUNTER ON THE ANIMAL CECONOMY.
 iound,  by  future observation and  experiments, that this structure,
 which is different from any that has hitherto been  described, is ca-


 an imperfect one, of this the natural type and perfection of a dioptric instrument
 which is supposed to converge the rays of light into a focus without any dispersion
 of the rays, and consequently without the production of false colours round the
 image.   Now the fact is that the image given by the eye is  not perfect with
 regard to colours in its ordinary exercise :  there is not only dispersion of the ray3
 of light, but the quantity of dispersion has been measured, and the different focal
 lengths of the eye for red and violet lights have been accurately determined by
 Young and Frauenhofer;  the latter philosopher, indeed, has found it  necessary
 to correct the dispersion of the eye in the construction of his achromatic object-
 glasses.   But to return to the structure of the crystalline lens,—this complex and
 beautiful part consists, according to Sir  David Brewster, of innumerable fibres
 of nearly the same length, each of which tapers from its middle part to its two
 extremities, like the gores or gussets of a globe.  In the lenses of some animals
 the extremities of all the fibres terminate in two opposite poles ; in others, in a
 line at each pole, the line  at the posterior pole being at right angles to the line
 at the anterior  pole, and all the fibres except a few  being bent into the most
 beautiful curves of contrary flexure.   In some lenses the fibres  terminate in the
 lines  of a rectangular cross at  each pole,  the line of the cross at one pole  being
 inclined 45° to the lines at the other pole ; in others, the terminations of the fibres
 form  more complicated figures.  In the  largest number of animals the arrange-
 ment  of the fibres is  the same at both poles; but in a few, such as the turtle, the
 fibres terminate in a different manner in the  two surfaces of the lens.  But the
 structure of each of the fibres is still more wonderful than their arrangement.  The
 sides  of each fibre are formed with teeth, like those of a watch-wheel, and the
 teeth  of one fibre lock  into those of the adjacent ones, apparently to strengthen
 them  and give body to the frail morsel of transparent jelly into which they are
 so marvellously moulded.
  In the lens of a cod-fish, four-tenths of an inch in diameter, Sir D. Brewster
 calculates the number of fibres to be about five millions, and the number of teeth by
 which the fibres are bound together to be sixty-two thousand five hundred millions ,■
 and as every tooth  has three  surfaces, the number of touching surfaces will be
 one hundred and eighty-seven  thousand five hundred millions ;  and yet this little
 sphere of tender jelly is as transparent as a drop of the purest water, and allows
 a beam of light to pass across these almost innumerable joints without obstruct-
 ing or reflecting a single ray !
  With respect to the  muscvilar theory of the  lens, and its supposed power of
 adjusting the eye to vision at different distances, by an alteration of its own
 form or dimensions, it is hardly necessary to state that these views have derived
 no support  since the time of Hunter, and of Dr. Young, who also entertained the
 theory of the irritability of the crystalline fibres.   It has, on the other hand, been
shown, in the well-attested case of Henry Miles,a that the eye  may retain its
 power of adjustment after the removal  of the lens.
  The supposed function of the lens, as an achromatic instrument, has been de-
duced from the structure which it presents in the human body, where the density
 of the fibrous layers diminishes from the  centre  to  the surface : a structure of
which the purpose is undoubtedly to correct spherical aberration:  but the lenses
 of quadrupeds display three different structures of varying density, separated by
 neutral lines, in which lines a density decreasing outwards passes into a density
increasing outwards.   This structure is well displayed in the lens of the horse ;
and when the animal has attained  a great age the densities of the central and
superficial  structures have  become uniform throughout, while the middle one
exhibits a  varying density more strongly marked than in  the youna lens, and
exhibiting by polarized light a brilHant yellow colour, like the most perfect  film3
of regularly crystallized bodies.   That these structures are  intended to correct
a See the Croonian Lecture, Phil. Trans,, 1802, voL xciu, p. &. 
OF THE ORGAN OF HEARING IN FISHES.          297
pable of producing consequent actions and effects, sufficient to ex-
plain the adjustment of the eye to different distances, it will not be
considered as a small or unimportant discovery.
   The  melancholy event which  has deprived this learned Society
of so valuable a member, and which has taken from me so able an
instructor, so rare  an example, and so inestimable  a friend, is too
recent  to  make any  apology necessary for the shortness or incor-
rectness of this account.  I thought it  due to the memory of my
friend that no promise of his, however inadequate I feel myself to
performance, should be left unfulfilled ; and the  circumstances of
distress under which it has been drawn up will procure for me every
indulgence from this learned  Society.
                                                 Everard Home.
  Leicester Square, Nov. 4,1793.
  29. AN ACCOUNT OF  THE ORGAN  OF HEARING IN
                              FISHES.*

   Natural history, having  ever  been  considered  as worthy the
 attention of the curious philosopher,  has in  all ages kept pace with
 the  other branches  of knowledge;  and as both arts and sciences
have of late  years  been  cultivated  to a degree  perhaps  beyond

 spherical aberration or to improve vision cannot be  doubted ; but the principles
 are yet  to be discovered  on which  that correction or improvement depends.
 Meanwhile it is the duty cf the physiologist to set plainly before himself, and to
 offer fairly to his pupils these unexplained or residual phenomena of the theory
 of vision ; not to  hide  them beneath an easily comprehended but insufficient
 illustration.  An achromatic lens, though highly desirable, indeed essential to
 the construction  of a good telescope or microscope,  is not therefore necessary in
 the eye : it is well  known to be less adapted for the  purposes of a camera obscura
 than a common lens; but  the organ  of vision has  a much closer analogy to a
 camera obscura than to a  telescope. In a telescope,  if there be colour, or disper-
 sion of the object-glass,  this must be greatly magnified by the eye-piece; and,
 what is still more essential, there  is an eye behind  the  instrument which takes
 cognizance of those  imperfections, and for whose sake they are endeavoured to
 be remedied.  But there is no eye behind the retina to view in the same manner
 the image which is thrown upon that membrane.   It  is well-known that  the
 retina is incapable  of transmitting a distinct idea of any spectrum depicted upon
 it save of that which is situated in or near  its axis; the colours of  the lateral
 pencils cannot be seen, and hence it is of no importance whatever to render the
 image achromatic at a distance from the axis.  When we wish to examine an ob-
ject, or a part of an object, with minute attention, we direct to it the axis of the eye;
 and in order to obtain a sensible colourless vision in or near the axis achromatic
compensation is  not necessary.  It is no doubt true that even in this axis there
is a non-coincidence of the  foci of the differently-coloured rays ;  but owing to the
 shortness of the focal distance of  the eye, and the low dispersive power of  the
 humours, this non-coincidence of the different foci does no injury to our  ordinary
 vision.]
  * [Originally communicated to the Royal Society, and printed in the Philoso-
 phical Transactions (vol. lxxii., p. 379) for the year  1782.] 
298           HUNTER ON THE  ANIMAL CECONOMY.
what was ever known before, we find that natural history has not
been neglected.   All the nations  of Europe appear solicitous  to
encourage the study; and in this island it has been pursued with
more philosophic  ardour than was ever known in any country.   It
has become an object  of pursuit to men possessed of affluent for-
tune;  which they have not only  dedicated to the cultivation of this
science, but  have even risked their health and lives in exploring
unknown  regions to increase  the  sources  of  information, and  in
settling  correspondences everywhere, so as to  bring  materials into
this country  that might render it the school of natural history.   It
is no wonder then that a spirit of inquiry is diffused through almost
all ranks of men; and that those who cannot pursue  it themselves,
yet choosing at least to benefit by the industry  of others, are eager
to be informed of what is already known.
   These reflections  have induced  me to publish this  short  account
of the  organ of  hearing  in  fishes;  for, although the existence  qf
such an organ is now known  to  many, it is still a subject of dispute
with others whether  they possess the  sense  or not.*
   Some time before I quitted  my anatomical pursuits, in the year
1760yf and went with  the army to Belleisle, I had discovered this

   * [Cuvier justly states that the structure of the organ of hearing was  better
known to some of the ancient anatomists in  the  class of fishes  than even  in the
human subject.  Casserius has given moderately good figures of the semi-circu-
lar canals and the ossiculum auditus of the pike in his work entitled  Pentestesion
(p. 224), published in the year 1600.  Steno, in the Acta Medica of Copenhagen
for 1673, described the internal ear or  the Squalus Mustelus, Linn., with tolera-
ble exactness, although without figures.
  Klein, in his Missus Historic Piscium permovendse, printed in the year 1740,
gives a detailed description and accurate figures of the ossicula  of the  ear of the
pike, salmon, trout,  umber, marene (Salmo Maraena, L.), herring, cod, dorsch
(Gadus callarius, L.), ling, pike-perch,  perch, gremille, stickleback, turbot, sole,
barbue  (Pleuronectes  Rhombus, L.), carp, barbel,  and  many  other species  of
Cyprinus.
  In 1753,  Etienne-Louis Geoffroy, a physician  of Paris, presented  to  the
Academy a memoir exprofesso on the organ  of hearing in fishes;  but this was
not printed till the year 1778.  He has described generally the ear of the eel, the
cod, the pike, the carp, the jjardon, (Cyprinus idus, Bio.), the flounder, and the
perch ;  but he  errs in ascribing to certain holes in the cranium the office of a
meatus auditorius externus, which they do  not fulfil.   The figures annexed to
this memoir, Cuvier informs us, were mislaid and lost, and therefore they did not
appear in the printed  essay.  The description of the ear of the rav was given  by
Geoffroy in a Memoir on the  Ears of Reptiles, presented in 1752, and printed
in 1755.]                                                       r
  f [Camper's  researches on this subject were made in  the year 1761: they
appeared first in the Haerlem Memoirs for  1762.  He afterwards sent a more
detailed memoir on the same subject to the Academy of Sciences of Paris  in
1767, which was printed  in the < Recueil des Savans Etrangers, t. vii.,' in 1774.
He describes in detail the organ of hearing of the ray, the cod, the pike, and the
lophius, with figures  in his style, t. e.,  somewhat vague.  He added but little to
that which Geoffroy had advanced, except that he denied too generally  the exter-
nal canal, and that he speaks of an  organ which he terms tensor bursse, which
seems only to be an appendage, or rather a ligament, more distinct  in the pike
than in most other fishes.                                           r
  In the year 1773, in the 17th vol. of the Novi Commentarii of St. Petersburgh 
OF THE ORGAN  OF HEARING IN FISHES.         299
 organ in fishes, and had the parts exposed and preserved in spirits.
 In some  the  canals  were  filled  with  coloured  injection,  which
 showed them to great  advantage, and  in others were so prepared
 as to fit them to be kept as dried preparations.*   My researches,
 in that and in every other part of the animal ceconomy, have been
 continued  ever since that  time.   I am still inclined to  consider
 whatever  is uncommon in  the structure of this organ in  fishes as
 only a link in the chain  of  varieties  displayed  in its formation in
 different animals,  descending from  the most perfect to the most
 imperfect,  in a regular progression/^
   As in this age of investigation a hint  that such an organ existed
 would be sufficient to excite  a spirit of conjecture or inquiry, I was
 aware  that there  would not be wanting some men who,  whether
 they only imagined the fact might be true, or really found it to be
 so, would be very ready  to assume all the  merit of the discovery
 to themselves.   My attention  was   more  strongly  called  to  this
 point by hearing, in conversation,  that some anatomists in  France,
 Germany,  and  Italy, had discovered the organ of hearing in  fishes,
 and  intended to publish on the subject.  I therefore thought  that it
 would be only justice to myself to deliver to the Royal Society a
 short account of that organ,  a discovery of which I had made more
 than  twenty years before.   This  account I shall reprint here,
 without  adding anything  to what I had before written, reserving a
 more complete  examination of this  subject for a larger work,  on
 the structure of animals, which I one day hope to have it  in my
 power to publish.
   I do not  intend to give a full account of this  organ in any one
 fish, or of the varieties in different fishes, but only of the organ in
 general;  those  therefore who may  wish to pursue this branch of
 the animal  ceconomy will think it deficient perhaps in the descrip-

 Kolreuter gave some very precise and detailed descriptions and figures of the ear,
 in two species of  sturgeon, the common  one (Acipenser Slurio, Linn.), and the
 huso (Acipenser Huso, Linn.).
  Monro described, better than any of his predecessors or successors, the external
 ear of the  Chondropterygii, in  his Anatomy of Fishes, published in 1785.
  Scarpa denies the external communication in the ray, which Hunter  correctly
 describes in the present memoir.]
  * I have injected these parts in other  animals, both with wax and metals;
which, the bone being afterwards  corroded  in spirit of sea-salt, make elegant
casts of these canals.
  f The preparations to illustrate these facts* have  been,  ever since, shown in
my collection, to both the curious  of this country and foreigners.   In  showing
whatever was new, or supposed to be new, the ears of fishes were always con-
sidered by me as one important article.b
  a [He here alludes to the series of other organs in his collection analogous to
those of the ear; and it is interesting to observe these incidental evidences of the
philosophical tendency in Hunter to view the varieties of structure, which his
numerous dissections displayed to him, as modifications of one type, or a graduated
and connected chain of varieties.]
  »• [See the Preparations in the Gallery of the  Hunterian Museum, numbered
from 1560 to 1574 inclusive.] 
300
HUNTER ON THE ANIMAL CECONOMY.
tive  parts.  If it was a difficult task to expose this  organ in fishes
I should perhaps be led to be more full in my description of  it, but
in fact there is nothing more easy.                              .
   It may be proper just to observe here, that the class called bepia
has the organ of hearing, though  somewhat differently constructed
from what it is in fishes.*
   The organ of hearing in fishes  is placed at the sides of the cavity
which contains  the  brain, but the skull  makes no part of it, as it
does in the quadruped and  the bird, the organ being a distinct and
detached part.   In some  fishes, as in  those  of the  ray kind, the
organ  is wholly surrounded by the parts composing  the cavity of
the skull; in others it is in part within the skull, or  cavity  which
contains the brain, as in the salmon, cod, &c, the skull projecting
laterally, and forming a cavity.
   The organ of hearing in fishes  appears to increase in dimensions
With the animal, and nearly in the same proportion, which is  not the
case with the quadruped, &c, the  organs being in them nearly as
large in the growing fcetus as in the adult.   Neither is its structure,
by any degree, so  complicated in  fishes  as in all  those orders of
animals which maybe reckoned superior, such as quadrupeds, birds,
and  amphibious animals; but  there is a regular gradation from the
first of these to fishes.
   It varies in different genera of fishes; but in all it consists of three
curved tubes, which unite  one with another ; this union forms in
some only one canal, as in the cod, salmon, ling, &c, and in others
a tolerably  large cavity, as in the ray kind.   In  the  jackf there is
an oblong bag, or blind process, which is an addition to these canals,
and  communicates with them  at  their union.   In  the  cod, &c, this
union  of the three  tubes stands  upon  an oval cavity ; and in the
jack there are two ; the additional  cavities in these fishes appearing
to answer the  same purpose  with the cavityj observed in  the ray
or cartilaginous  fishes, which  is at the union of the three canals.
   The whole organ is composed of a kind  of cartilaginous substance,
very hard or firm in some parts, and in some fishes crusted over with
a thin bony lamella, to prevent it  from collapsing; for as the skull
does not form any part of these canals  or cavities, they must be
 composed of a substance capable of keeping its form.

   * [This is the first announcement of the existence of an organ of hearing in the
 Cephalopoda. It differs from that of fishes in  the absence of the semicircular
 canals, and exhibits a simpler stage of structure, consisting of  a vestibule, with
 the nerve, fluid, sacculus, and ear-stone or otolithe.  The low-organized Cyclos-
 tomous fishes manifest their character as transitional links between the inverte-
 brate animals in  several parts of their  structure, but more especially in the organ
 of hearing.  The myxinehas a vestibule, with one canal extended from it.  The
 lamprey shows a further stage  of complication,  in having two  canals continued
 from the vestibule.  All the osseous  fishes have  three semicircular canals, as
 described in  the text; and the plagiostomons cartilaginous fishes, as the sharks
 and rays, exhibit a higher type of structure, in having the  internal ear inclosed
 within the parietes of the cranial cavity, and in the  external communication or
 meatus which some of the species present.]
   |  [Esox Lucius,  L.]                        X {Sacculus vestibuli.'] 
OF THE ORGAN OF HEARING IN FISHES.        301
  Each tube describes more than a semicircle, resembling, in some
sort, what we find in most other animals, but differing in the parts
being distinct from the skull.*
  Two of the semicircular  canals are similar to one another, may
be called a pair, and are  placed  perpendicularly; the third is not
so long, and in some is placed horizontally, uniting  as it were the
other two at their ends or terminations.   In the skate this is some-
what different, the  horizontal  canal being united only to  one of the
perpendicular canals.   The two semicircular canals, whose position
is perpendicular, are  united, forming one canal;  at their other ex-
tremities they have no connection with each other, but join  the ho-
rizontal one, near its  entrance  into the common cavity.   Near the
union of these canals they are swelled out into round bags' (ampullce),'
and become much larger.
  In the ray kind  all  these canals terminate in one cavity, and in
the cod in one canal, placed upon the additional cavity or cavities,
in which there is a bone  or bones.  In some there are two  bones;
and in the jack, which has two cavities, we find in one of  them, (the
accessory sacculus of the  vestibule,)' two bones, and  in the other
'  (the ordinary sacculus of  the  vestibule,)' one  ; in the ray there is
only a chalky substance/f
  In some fishes the external  communication, or meatus, enters at
the union of the  two  perpendicular  canals, which is the case with
all  the ray kind, the external orifice  being small, and placed on the
upper flat surface  of the head ;  but it is not every genus  or  species
of fishes that have the external opening.J
  The nerves of the ear pass  outwards from the brain, and  appear
to terminate at once on the external  surface of the enlarged  part of
the semicircular tubes above  described.^   They  do not appear to
pass through these tubes so as  to  get on the inside, as is supposed
to be the case in qundrupeds; I should therefore very much suspect

  * The turtle and the crocodile  have a structure somewhat similar to this ; and
the intention is the same, for their skulls make no part of the organ.
  f This chalky substance is also found in the ears of amphibious animals.a
i  X [Hunter had a drawing made of these orifices  in the  monk-fish (Squatina
Angelus, Dum.), which has been engraved  and published in the third volume of
the  Physiological Catalogue of the Hunterian Museum,  pi. xxxiii. fig. 1, a.]
  § [The acoustic nerve comes off from the brain, nearly opposite the junction of
the sacculus with the vestibule; it sends off from its upper part a filament to each
of the semicircular canals : this  filament penetrates  the ampulla of the  canal to
which it appertains, and is there  lost.  Another division of the nerve goes to the
vestibule, but by far the greatest  part of it spreads out into a number of filaments
which form a very beautiful apparatus, under the parietes of the sac which con-
tains the large stone.]
  ? [In these it is lodged in a small blind sac, communicating with the vestibule,
and representing the cochlea in a rudimental state.  In the ray also, the vestibule,
after receiving the orifices of the semicircular canals, opens into a large oval sac,
which gives off two appendages, one anterior, the other posterior; this sac is
analogous to the rudimental cochlea in reptiles, as is also the sacculus vestibuli
in the osseous fishes.]
                                  27 
302          HUNTER ON THE ANIMAL CECONOMY.
that the lining of the tubes in the quadruped is not nerve, but a kind
of internal periosteum.
  As it is evident that fishes possess the organ of hearing, it becomes
unnecessary to make or  relate  any experiment  made with living
fishes, which only tends to prove this fact;  but I will mention one
experiment, to show that sounds affect them  much, and is one of
their guards,  as it is in  other animals.  In  the year 1762, when I
was in Portugal, I observed in a nobleman's garden, near Lisbon,
a small fish-pond full of different kinds of fish.   The bottom  was
level with the ground, the pond  having been made by forming a
bank all round, and had a shrubbery close to it.  Whilst I lay on
the bank observing the  fish swimming about, I desired a gentleman
who was with me to take a loaded gun and fire  it from behind the
shrubs.  The reason for desiring him to go  behind the shrubs was,
that  there  might  not  be   the  least  reflexion of  light.   The
moment the report was made  the   fish  seemed  to  be all of
one mind, for they vanished instantaneously, raising a  cloud of
mud  from the bottom.   In about five minutes  afterwards they
began to appear, and were seen swimming about as  before.
   Mons. Geoffroi, who has written on this organ, considers the ray
as in the class of reptiles, and with that idea has examined their
organ of hearing.   He is by no means  clear in  his description, so
that it is  almost impossible to follow him ;  yet it is  but doing him
justice to  allow that he  has discovered what is  analogous to the
three semicircular canals in other animals, together with their union
into  one cavity.   He  mentions the chalky substance contained in
that cavity, and also the nerves; but  it is by no means clear that
he was acquainted  with the external opening  which leads  to these
canals.  He says, " The entrance of the organ of hearing (by which
one would suppose he means the meatus auditorius externus) is not
easily discovered;'' but that which  he  describes  does not corres-
pond with the real  situation of the external  communication ;  we
may therefore reasonably conclude that he is describing something
else.  He is not more clear  in his mode of reasoning on the appli-
cation of  the parts to produce the sense of hearing.  He observes
that the organ of hearing is very imperfect in this species of animals,
but supposes this to be compensated by the medium  in which they
live, and by  which  sound  is  conveyed to them, being more dense
than that of the air, by which sound  is communicated to animals
living  on  the land; and of this  idea  he  is certainly the author.
Mons. Geoffroi  cannot indeed be  said  to have given a perfect
account of the organ of hearing in fishes, yet on the whole he should
be considered as a discoverer; for though he  only made his obser-
vations on  the ray, as belonging to the class of reptiles,  yet as it
may be properly considered of the fish  kind, he  has  a just  claim to
that credit.  Had 1 formerly been acquainted  with this  author's
researches and pretensions, I should not have claimed that to which
I had not a prior  right: nor should I  have held the discovery of
the external  communication alone, an object of consequence enough
to induce me to dispute the honour with Mons. Geoffroi. 
OF  ABSORPTION BY VEINS.
303
  In  looking  over the  works of the different  authors who have
treated of the organ of  hearing in fishes, I find from a  passage in
Willoughby,*  who published prior to Mons. Geoffroi, and indeed is
quoted  by him, that my claim, even to the discovery of the external
opening, is not so  strong as I believed it  to be, as he mentions an
external orifice  in  the skate contiguous  to what he supposes  the
organ of hearing in that fish.   If what he alludes  to is really the
external opening of the ear, it gives  him a prior claim to the disco-
very  of that part of the  organ, although from his account, he does
not seem to have been acquainted with the organ itself; for, as in
describing the external ear of the thornback, he has evidently mis-
taken the nose of it, of which he gives a tolerably full account, it is
very  obvious that he  was ignorant of the opening into the ear.f
  Although Professor Camper published an account of the organ
of hearing in fishes so late as 1774, he did not seem  at that time to
have been acquainted with the external opening of the ear in the
ray.   After giving a description of the organ of hearing in the pike,
he makes some  general  observations on the similarity of this organ
in other fishes, but excepts the shark and ray.J   This exception we
might  suppose  alluded to the auditory canal, but  further on  he
explains what is meant by this exception, and does not mention the
external  opening in  the ray, from  which  we may  fairly conclude
that  he was not acquainted with it.§
             30. OF ABSORPTION BY  VEINS.||

  [Dr. Hunter introduces the account of his brother's experiments on this subject as
                              follows.]

  In both  my courses of the winter  1759-60, I went so far as to
say, I believed that the red veins did not absorb; and gave  my rea-

  *  Willughbeii Historia Piscium, Oxonii 1686, lib. iii. cap. viii.
  f Lib. iii. cap. xiv.
  X " II  est tres-vraisemblable que toutes les autres  especes de poissons, tant
malacopterygii qu' acanthopterygii, aussi-bien que les  branchiostegi & les  chon-
dropterygii d'Artedi, a l'exception des squales & des raies, ont l'organe de l'ouie
construit a peu pres de la meme facon ; je n'excepte pasl'esturgeon, quoiqueM.
Klein, ibid, ait donne la description du conduit auditif,page 19, figure A, Tab. 2.
b; ce poisson £tant rare parmi nous, je n'ai eu occasion de l'examiner qu'une
seule fois sans avoir trouve ce conduit."  Memoirs Etrangers de l'Academie des
Sciences, 1774, torn. G, page 190.
  § " Au contraire, les chiens de mer, lesga/eisdeRondelet & les poissons qu'il
a decrits, lib. XII.; les squalis  d'Artedi & les raies, ont bien l'organe a peu pres
de la meme  composition, mais  il  est  enferme dans une caisse tout osseuse ou
cartilagineuse, ce qui ne fait pas  une difference essentielle; ils entendent done
comme le eglefins, les morues,  les baudroyes & les brochets, en un mot comme
tous les autres poissons non amphibies: M.  Geoffroi s'est trompe en comparant
leurs organes avec celui de reptiles, tels que  la vipere, les lezards, &c. qui enten-
dent le son comme les quadrupedes, les oiseaux & les  amphibies aquatiques,
savoir par le moyen de Pair &  d'un tambour, comme  j'ai dessein de le prouver
dans une autre occasion."   Memoires Etrangers de l'Academie des Sciences,
1774,torn. 6, page 190.
  || [Medical Commentaries, Part I., p. 39.] 
304          HUNTER ON THE ANIMAL CECONOMY.
sons for  thinking so; and in different  parts of my lectures I used
to treat of the transudation and absorption of fluids in  animal bodies
in the following manner:
   " I have  often considered with myself how the interstitial fluid
gets into the smaller  and  greater cavities of our bodies ; how  the
water of an anasarca, for instance, gets into the cellular membrane.
The common opinion, I think, is, that there are everywhere exhalant
arteries,  which open and terminate on the superficies of such cavi-
ties, and throw out the watery fluid which they contain.   But for
my own part, I cannot help believing that it is  entirely by transuda-
tion through the coats or  sides of the  vessels.   My reasons  for
thinking  so are these :
   " First, so far as I can find, all the arguments of the latest and
best anatomists, taken from  injecting the  arterial system  in  dead
and living bodies, only prove that a thin fluid  passes  readily from
the arteries  into the interstices of parts.  They do not prove  the
existence of exhaling branches more than they prove transudation.
   " In the second place, the phenomena of injections, so far as  I
have been able to make observations, agree better with the notion
of transudation than with that of exhaling  arteries.  I have had
great experience of  injections, and I have made experiments with
all sorts of fluids injected into the arteries and  veins of dead bodies.
I have always observed that subtile and penetrating fluids pass with
ease from the arteries into the cavity of the  intestines, and into  the
cellular membrane in any part of the body: such fluids are water,
gum-water,  whites of eggs  strained,  glue, isinglass dissolved  in
water or  spirits, any fluid oil, melted butter or axunge, &c.  But
,..U„., *U---a.y.-t-------  ,7_____j  „.;4u „_.....Mr... t  „i______  -i-_„___J
wucu mcsc iiuius were coiuuicu  wim vciiniiiun i  uiwa^s udsoi vcu
that none of the vermilion  passed out  of the  arterial system  but
when there were manifest appearances of extravasation and rupture
of the vessels:  I never  observed vermilion pass into the cavity of
an intestine  from the mesenteric arteries, without seeing a hundred
ruptures  and extravasations  in the villi of the  gut.   All this looks
as if the fluid oozed through the  coats rather  than was poured  out
by the branches of arteries.
   " In the third place, I have observed that  the cellular membrane
is not  so immediately filled  by  injecting the  arteries ; it requires
some time, and I have plainly seen, when I have let an injected part
lie by a little while, that the cellular membrane became gradually
more loaded as the  arterial system became more empty: a strong
argument, in my mind, that it got out of the arteries by transudation.
   " In the fourth place, water and even  red blood soaks through
all our vessels and membranes in dead  bodies ; as you may see by
steeping the apex of a  heart well washed,  or  the convolution of a
piece of fresh intestine  in clear water; in both cases the water will
become bloody.
   " But still it is said that in all these cases  the fluids  pass by fine
exhaling vessels, though these vessels  cannot  be seen.  To  this I
 answer that if our interstitial fluid was of a strong marked colour, 
OF ABSORPTION BY VEINS.
305
we should  then  by dissection be able to observe whether it was
poured  out by  small arteries, or whether it soaked through the
natural  pores in  the coats of vessels.   Now, very fortunately for us
in this dispute, there is one  such fluid in the body: it  is  the bile.
Its colour is pretty deep, and very different from anything that lies
near the gall-bladder.  No man  can have opened any number of
bodies without allowing that the gall does pass through all the coats
of the gall-bladder, and pervades the substance of the neighbouring
parts, not by exhaling nor by inhaling vessels, but by manifest tran-
sudation or soaking.
   " It might be  asked, why the red blood does not transude through
the vessels in living bodies; for  I think it certainly does not.  In
answer  to this it may be said  that our fibres and  vessels have per-
haps some  degree of tension and firmness in life  which they lose
with  life; and it must be observed too, that  in proportion  as the
blood purifies  it becomes  thinner; whence we  see, in  opening  a
putrid body, all  the cavities more or less filled with a bloody water,
and all  distinction of colour in the muscles and cellular membrane
quite  lost.  But  what I suppose to be the principal reason that red
blood does not transude through  the  vessels in living  bodies is  its
glutinous quality, its thickness while it is equally mixed up with its
coagulating part.   That part  coagulates as  certainly as the blood
stagnates even in living bodies ;  and when the universal stagnation
happens in  death, this part of the blood collects itself into irregular
polypi and coagulations all over the body, and the  rest of the blood
is no  longer the  thick viscid fluid  it was before, but rather  a bloody
serum,  that will ooze through all the vessels and membranes/'
   Such were  my notions  of the source of our  interstitial fluid.
With regard to  its  absorption, I was  of  opinion  that Nature had
provided a system on purpose, viz., the lymphatics.  I  considered
these vessels and the lacteals as an appendage to the venal system,
by which the stores were brought in for supplying the circulation;
and the glands and secretory vessels all over the body I considered
as an appendage to the arterial system, by which the  proper sepa-
rations  were made, and the redundancies thrown off.
   My only doubt was whether the veins  did  or  did not absorb a
certain  quantity, especially in the intestines.  From my  own obser-
vations  on  injections I  should have concluded that they did not,
and that  there was no  passage for  liquors  between an intestine
and the mesenteric veins otherwise  than  by transudation.  But
authors of the  best credit had given such  arguments and experi-
ments in favour of absorption by veins, that I dared not, even in my
own mind, determine the question.
   At this time  my  brother was  deeply  engaged  in physiological
inquiries, in making experiments  on  living animals, and in prose-
cuting comparative anatomy with great accuracy and application.
It is well known that I speak  of him with moderation when I say
so.  He took the  subject of absorption into  his consideration, and
                              27* 
306          HUNTER ON THE ANIMAL CECONOMY.
from all his observations was inclined to believe that in the  human
body there was one, and but one, system of vessels for  absorption.
He knew  so well that many things had been asserted by one person
after another which were not true, that so many mistakes had been
made from inattention, so many errors introduced  from other
causes, that he could easily suppose  the veins  might  not perhaps
absorb, after all  the demonstrations  that  had been  given of the
fact;  and therefore was determined to see how far this point could
be cleared up by plain experiments and observations.  With that
intention he made the following experiments, in my presence and in
the presence of a number of gentleman, who all of us assisted him,
and made our own  observations upon what passed before us.   I
shall quote the experiments from him, and can bear testimony to
the fairness with which they were made and  with which they are
here related.
  " Animal First.—Experiment I.  On the 3d of November, 1758,"*
says he, " I opened the belly of a living dog.   The intestines rushed
out immediately.  I exposed them fully; and we observed the lacteals
filled with a white liquor at  the upper  part of the gut and mesentery ;
but in those which came from the  ileon  and  colon the liquor was
transparent.
  " I tied  up the mesenteric artery and vein that was going to about
half a foot of intestine, and  put a tight ligature upon the upper part
of the intestine, including a little  of  theumesentery ; then emptied
that part of the gut by squeezing it downwards, and put  a  similar
ligature upon the lower part of the gut.  In the next place, I made
a small hole in the upper end of this part of the gut, and by a funnel
poured in  some  warm  milk, and confined it  by making  a third
ligature upon the gut close to this hole.  These  ligatures prevented
the circulation of blood in this part of the  bowel.   Lastly, I punc-
tured  the vein beyond the  ligature that  had  been  made  upon the
mesenteric vessels, and by gently stroking with the end of the finger
soon emptied it of its blood.
  "Experiment  II.  I immediately after this made the same experi-
ment, and in the same manner, on a part of the intestine lower
down, where the lacteals were filled  with a transparent liquor.
  " In the first experiment the lacteals continued  to  be filled with
a milky or white fluid: in  the second, the lacteals, which before
contained only a transparent lymph, were presently filled with white
milk.
  " In both these experiments we could not observe that the least
white fluid had got into the veins.  After attending to these appear-
ances a little while, I put all the bowels into the abdomen for some
time, that the  natural absorption might be  assisted by the  natural
warmth;  then took out and examined attentively  the two parts  of
the gut and mesentery upon which the experiments had been made:

  * In presence of Doctors Clayton, Fordyce, and  Michaelson, and Messrs.
Blount, Jones, Churchill, and Richardson. 
OF ABSORPTION BY VEINS.
307
but the lacteals were still filled with  milk, and there was not the
least appearance of a white fluid in the veins;  on the contrary, what
little blood was in them was just as thick and as  deep-coloured as
in the other veins, and  when squeezed out from them coagulated as
the blood of other  veins.
   " Experiment III. I tied up  and filled another piece of the  intes-
tine with milk in the same manner, but did not make a ligature upon
the  mesenteric vessels,  leaving a free circulation in  the part.   We
looked very attentively at the  colour  of the blood in  the vein of that
part, both with our naked eyes and with  glasses:  we compared it
with that in the artery  and in  the neighbouring veins, but could not
observe that it was lighter-coloured, nor that it was  milky, nor that
there was any difference whatever.
   Experiment IV. Lastly, we took that part of the gut which was
filled with milk in the first or  second  experiment, and squeezed and
pressed it very gradually, in order to see  whether any milk would
by these means pass into the empty mesenteric  veins.  This we
did  gradually, with  more  and  more force, till the gut at last  burst;
but still there was not the least appearance of anything milky in
the  veins.
   "Animal Second.—Experiment  I.   November  13,  1758,*  I
opened the abdomen of  a living sheep, which had  eat nothing for
some  days, and  upon exposing the intestines and mesentery we
observed the lacteals were visible, but contained only a transparent
watery fluid.  I made a hole in  the intestine near the stomach, and
by a funnel poured in some thin starch, coloured with indigo, so as
to fill  several convolutions ;  then tied up  the  whole  in the gut, and
put all the bowels into  the abdomen for  some time.  Upon  taking
them  out after this we observed all the lacteals of that part filled
with a  fluid of a  fine blue colour/}-  We  thought at  first that the
   * In  presence of Doctors Wren, Fordyce, and Michaelson, and Messrs. Blount,
Tickell, Churchill, Paterson, and Skeette.
   X  [Martin Lister, in 1682, injected twelve ounces of the tincture of indigo into
the small intestines of a living and  fasting dog.  At the time of the experiment
there " was  not the least appearance  of lacteal veins in the mesentery:" after
full  three hours the mesentery was examined, and many lacteals were found of
an azure colour ; and some  of the biggest of them being cut, a  thick bluish chyle
was seen to issue forth.  (Phil. Trans., vol. xiii., p. 9.)  The conclusion which
Lister  drew from this experiment with reference to the power of  the lacteals to
absorb extraneous matters along with the chyle, was opposed in his time by some
writers, and it was stated " that people may be deceived with blue tinctures, for
this is the natural colour of these  lacteals when they are almost or altogether
empty."  See Phil.  Trans., No. 275, October, 1701, p. 996.
   In order to try the value of this  objection, Dr. Wm. Musgrave instituted the
following experiments:
   " Feb. 1682-3.   I injected into  the jejunum of a dog, that had for a day before
but  little meat, about twelve ounces of a solution of indigo in fountain water, and
after three hours, opening the dog a  second time,l observed several of the lacteals
of a bluish colour, which,  upon stretching of the mesentery, did several times
disappear, but was  most easily discerned when the mesentery lay loose; an
argument that the bluish colour was not properly of the vessel, but of the liquor
 contained in it.
   " A few days after this, repeating the experiment in another company, with the 
308          HUNTER ON THE ANIMAL  CECONOMY.
blood in the veins of this part was of a darker colour, but on com-
paring it  carefully with that  in the other veins it was manifestly
the same.
   " Experiment II. I  opened  a vein upon this part of the mesen-
tery, and catched a table spoonful of its blood.  I set it by to con-
geal and separate into  its coagulum  and serum.   On the next day
and the day after that I examined the colour  of  the serum, but it
had not the least bluish cast.
   " Experiment III. I fixed an injecting pipe in an artery  of the
mesentery, where  the  intestine  was filled with the blue starch, and
tied up all  communications both in the mesentery and intestine (as
in Animal  First, Exper. I.), but left  the corresponding vein free;
then I injected warm milk by the artery till it returned by the vein,
and continued doing so till all the blood was washed away, and the
vein returned  a bright white milk.   This was done  with a view of
seeing if the  milk in the vein  acquired any bluish cast, but there
was no perceptible difference between the arterial and venal milk.
   " Experiment IV.   After  this I opened  the vein  with  a lancet,
and discharged most of the milk, then put a ligature upon  both the
artery and vein, and   waited some  time to see  if they would fill,
but they did not, nor did the remaining contents of the vein acquire
the least bluish  cast.   Then I opened  the gut at this part, but we

solution of stone-blue in fountain water, and on a dog that had been kept fasting
thirty-six hours, I saw several of the lacteals become of ^perfect  blue colour within
very few minutes after the  injection :  for they appeared so before I could sew up
the gut. At about the beginning of March following, having kept a spaniel fasting
thirty-six hours,  and then syringing a pint of a deep decoction of stone-blue with
common water into one of the small guts, and after three hours opening  the dog
again, I saw many of the lacteals of a deep blue cohur.  Several of them were
cut, and afforded a blue liquor  (some of the decoction), running forth on the
mesentery.
  "After this I  examined  the ductus thoracicus (on which, together with other
vessels near it, 1 had  upon  my return made a ligature), and saw the receptaculutn
chyli and that ductus of a bluish colour, not so blue indeed as the lacteals, from
the solution mixing in and  near the receptaculum with lympha, but much bluer
than the ductus uses to be, or than the lymphatics under Ihe liver (with which I
compared it) were.  I trusted not my own eyes in any one of these experiments,
but in each of them had the company and assistance of several physicians, who
all agreed with me as to the colouring of the lacteals."  (Phil. Trans., No. 275,
October, 1701.)
  The same objection, the  force of which was invalidated by the experiments of
Musgrave, has been in recent times urged against the experiments of Hunter,
related in the text; but it is obvious that it cannot apply where care is taken to
observe the colour or appearance of the empty or transparent lacteals before throw-
ing the coloured fluid  into the intestine, and to contrast that appearance of the
lacteals with the colour which they present after the  experiment has been per-
formed.  Now this precaution Hunter invariably adopted.
  With reference to the experiments on the lacteals recorded in the early numbers
of the Philosophical Transactions, it may be observed that they differ from those
of Hunter in the absence of observations and modifications  which  the latter
physiologist  combined with them, in  order to test the share  which  the veins
might take  in the absorbing processes;—a question which does not appear to
have occupied the attention of either Lister or Musgrave.] 
OF ABSORPTION BY VEINS.
309
could not  observe any appearance of the milk having got into the
cavity of the intestine.
  " Experiment V.  I filled another part of the intestine with milk.
All that we observed after doing this was, that the lacteals became
fuller, though not of a white colour, and the veins remained of the
same complexion.
  "Experiment VI. I fixed a pipe into the vein of  the mesentery,
and injected  milk towards the intestine, to see if any would pass
into the cavity  of the gut; but presently innumerable extravasations
happened, so that the experiment was fruitless.
  " Experiment VII.  I fixed a pipe into an artery, and tied up the
vein and all the communications;  then injected milk for some time
into the artery till the vein became quite  turgid and tight;  this
was continued  for some little time, and with as much force as we
thought the vessels would bear without bursting; then we opened
the intestine at that part, and there was no  appearance of milk in
its cavity.
  "Experiment VIII.  I took a piece of the intestine that was quite
empty and clean, and filled it  with  warm water.  The returning
blood in the vein of this  part appeared not at all diluted or thinner
than in the other veins.  Then  I tied up the artery and all the com-
munications, and attended to the state of the vein for  some time;
it did not  grow more  turgid, nor did its blood become more watery,
nor was there any appearance whatever of the water's having got
into the veins.
  "The animal was  quite alive all  the time of our making these
experiments and observations, which  lasted from  one o'clock till
half an hour  after three.  I chose a sheep rather than  a dog, both
because the animal was much  larger, and therefore its mesenteric
vessels were fitter for being easily injected, and besides, because it
is much more patient and quiet.   These advantages we were all
sensible of when we made the experiments.
  " Animal Third.—June 22d,  1759.   We repeated most of these
experiments  on another sheep, to see if the  effect would be the
same, but in this animal  the  viscera  were diseased, inflamed, and
thickened  in most parts, so that the experiments were much less
successful, less satisfactory, and  conclusive.   After injecting milk
into the mesenteric artery for some time, and allowing it to return
by  the vein, we opened that part of the intestine which had been
previously emptied, and found in it a  watery fluid of a whitish cast,
as if a few drops of milk had been mixed with it.
   " Animal Fourth.—In  July, 1759,* I repeated most of the expert
ments related in article Animal Second, upon another sheep.   The
effect of all of them was so nearly the same that I  need not be
particular.
   " I shall only observe, that  when the intestine was filled with
starch-water  and indigo, and  milk  injected by the artery till the
  * In presence  of Doctors  Macaulay, Ramsey, and Michaelson, and Messrs.
Edwards and Tomlinson. 
310          HUNTER ON THE ANIMAL CECONOMY.
vein was washed clean of blood, and a ligature put upon the artery
and vein, so as to leave them about half full  of" pure  white milk,
after waiting more than half an hour we could not observe that the
vein was in the least more filled or turgid, nor had the milk in the
veins acquired the least of a bluish cast, not even in the small veins
upon the gut itself, where we should suppose the absorbed liquor
must  have  been apparent if any had  been taken up  by the veins
from the cavity of the intestine.
  "After the animal  was dead I blowed into a mesenteric vein, and
the air found a passage  into the cavity of the gut; though in
making the experiment when the animal was alive, I could not force
the milk by  injection  from the vein into the gut.
  " Animal Fifth.—If any animal  could be supposed a  fitter subject
for such experiments than a sheep, it would be an ass.  He is not
so large nor so strong but that he may be  managed ;  he is patient
in the  greatest degree ;  his mesentery and vessels being larger, it
is so much more easy to  fix injecting pipes, make ligatures, &c.;
and, what is a very great advantage in making such  experiments,
his mesentery  is very  thin, without fat, so that the vessels are
conspicuous and distinct.  Hence it is easy to separate the artery
from the  vein, to fix pipes, to tie up anastomosing  vessels  by a
needle, &c.
  V Therefore I got an ass, and on the 24th  of August, 1759,* put
him upon  his back  in  an  open  garden, and tied him fast to four
stakes  drove into the ground, then opened his abdomen, &c.
  " Experiment I. I  poured a solution of musk in warm water into
a piece of the intestine, and confined it there by two ligatures. In
doing this the  animal struggled, and a little  of the liquor was spilt
upon the outside of the intestine and mesentery.
  " After  waiting a  little  while, I opened with a lancet some lac-
teals of this part, which  were full of a watery fluid, and catched a
little of their contents in a small spoon.  It smelled strongly of the
musk,  and  though it could hardly be  doubted that the musk had
been taken up from  the  intestine by absorption, yet as some of the
musk-solution had been spilt upon the external surface of the parts,
and  as it was  impossible to collect  the lymph from the lacteals
without resting the edge of the spoon upon the mesentery, the smell
of the spoon might be owing to that circumstance.
  " After  this 1 wiped a vein upon the mesentery very clean, and
opened it with a lancet: a gentleman who had kept out of  the way
of the   musk came  immediately  with a clean spoon,  and  filled it
from the stream  of blood without  touching any part of the animal,
and carried  it directly off, but it had not the  least smell of musk.
  " Experiment II. We poured some starch-water, made very blue
with indigo, into a part of the gut in the same manner as  in some
of the   former experiments, tied  the vein and artery  of this  part,
then punctured the vein close to the ligature, and pressed out almost
  * In presence of Doctors Macaulay and Michaelson, and of Messrs. Edwards
White,  and Gee.                                                ' 
OF ABSORPTION BY VEINS.
311
all the blood; then tied up the empty vein, and put all into the cavity
of the belly for a quarter of an hour.   After that we examined the
part, found the  lymphatics very turgid, as the fluid could not pass
through them towards the thoracic duct on account of the ligatures
made upon the  mesenteric  vessels; but we found  the veins of this
part empty, except indeed that a little blood had got into them from
the neighbouring vessels, which,  from the  appearance, had evi-
dently passed the ligatures tied round the ends of the gut, a circum-
stance which it  is very difficult to obviate.
   " Experiment III.  I next repeated the Third Experiment of Ani-
mal  Second exactly in  the  same  manner, and precisely with the
same effect.
   " Experiment  IV.  Then  I repeated the  Fourth Experiment of
Animal Second, and the effect was still the same.
   " N. B. It may not be amiss to observe that the lacteals continued
to absorb  the bluish liquor  all this time, even at the  part  upon
which this Fourth Experiment was made,  where  the nerves must
necessarily have been  tied up with the artery.
   " Experiment  V.  I squeezed a piece of  the intestine so as to
empty it as entirely as well might be, then tied up all  the lateral  com-
munications of the vessels, and injected warm milk into the mesen-
teric vein till it  returned by the artery, and continued this operation
for some time after  all the blood was washed out.   Then I opened
that part of the intestine  through its whole "length, and found it quite
empty.
   " I made this  experiment again  upon another part of the intestine,
in the same manner, and exactly with the same success."
   Here is  a new doctrine proposed in physiology, viz., that the red
veins do not absorb in  the  human body.  The fair inquirer after
truth will be convinced, by the observations which  occurred to me,
that the common opinion,  that they do  absorb,  is supported  by
some proofs  that are at least  doubtful or equivocal, and  that the
other opinion is not without plausibility; and he  must allow that
my brother's experiments render it highly probable.
  [In attempting to form a correct estimate of the merits of Mr  Hunter
as a discoverer in reference to the absorbent system, it becomes necessary,
in the first place, to distinguish  between the  discovery  of the vessels
themselves, whether  lacteals or lymphatics,  and that of their functions
and  anatomical relations to the other parts of  the vascular system.
  With respect to the Mammalia, it is scarcely necessary to observe that
the  existence of  both lacteals and  lymphatics  had been determined in that
class long before the time of Dr. William Hunter.
  The discovery  of the lacteals  by  Asellius  was first  made publicly
known in 1628 ;  and thaf of the thoracic duct by Pecquet  in 1651.
  In  1652 our  countryman Joliff, having  placed a ligature  round the
spermatic  cord,  saw, upon squeezing the testicle, that certain  vessels,
which he termed ' vasa lymphatica,' became turgid ; he did not, however, 
312           HUNTER ON THE ANIMAL CECONOMY.
himself publish this observation, and it might never have seen the light,
had not,  in the meanwhile, the  attention  of the anatomical world been
drawn to the lymphatic vessels by Bartholinus, an illustrious philosopher
of Denmark, in 1651, and by Rudbeck, a Swede, and professor at Upsal,
in 1652.
   In  1668, M. Louis  de Bills appears to have traced lymphatic  vessels
from  the  'jugular  glanduls' of a  dog to  the thoracic duct.   See Phil.
Trans., iii. (1668), p. 791.
   But the lymphatic absorbents had never been distinguished as a system,
either anatomically or physiologically, from the capillary  vessels.
   Noquez, who of all anatomists before the Hunters, had  dwelt more par-
ticularly  on* the lymphatics, and who was cited  by some of the contem-
poraries of the Hunters as having anticipated them  in this department of
their anatomical labours,  divided the lymphatics  into four classes : one of
these corresponded with  the capillary blood-vessels of modern physiolo-
gists ;  a  second,  with  the  serous exhalant arteries ; a third, to the veins
corresponding with these arteries, and to  which Noquez gave the name
of ' conduits  absorbents,'  until they became large enough to be sensible
to the naked  eye, and  began  to receive red blood.   His fourth class of
lymphatics includes the  absorbent vessels  of  the Hunters,  and  were
described by Noquez  as ending  in the receptaculum chyli, the thoracic
duct, the vena cava, and  the vena portarum.
   It is therefore obvious  that the Hunterian doctrine of the absorbent sys-
tem  was  in no way anticipated by  Noquez, who appears to have been a
mere compiler, undistinguished by any  original  research, and  whose
anatomical treatise was professedly an improvement upon Keill's.
   With respect to the  extension of our knowledge of the  condition of the
lymphatic system in the human subject, it  appears that Mr. Hunter greatly
contributed to this important branch of anatomy.   Dr. Hunter describes
One of his preparations,  which showed the lymphatic vessels extending
from  the ham upwards to  the thoracic duct, as  well as the  inguinal and
lumbar glands, and  the  larger lacteals at the root of the mesentery, the
receptaculum chyli, or what is so  called,  all finely filled with mercury.
He acknowledges his brother's discovery  in 1753 or 1754, that the lym-
phatic glands, and the  lymphatic vessels going from them, could be filled
uniformly by pushing a pipe into their substance :  and states it to have been
Mr.  Hunter's intention to  have  traced the lymphatic vessels all over the
body, and to  have given a complete  description  and figure of the  whole
absorbing system.   This  work was unfortunately  arrested  by a  very
indifferent state of health, the effect of too much application to anatomy,
which obliged Mr. Hunter to be much in the country. It was  afterwards,
as is well  known, ably accomplished by  another  ornament of the Hun-
terian school, the celebrated Cruikshank.
   When  the  question of  the office of the lymphatics  first began to be
agitated, one of the arguments against their being the exclusive agents of
the absorbing processes  was  founded on  their  supposed absence in the
oviparous vertebrata.*   The discovery of this system of vessels  in birds

   * [« Lacteal vessels have not as yet been certainly observed in birds, or in the more
common fishes, nor in general m the animals called oviparous ; and, from a considerable
number of experiments I have made, I am convinced they want the lymphatics as well
as the lacteal vessels."   Monro,  Observations  Anatomical and  Physiological  8vo
Edinb., p. 57,1758.                                                 ' 
OF ABSORPTION BV VEINS.
313
formed, therefore, no  unimportant support to the views of Dr. William
Hunter, and to this discovery Mr. Hunter is justly entitled.  Mr. Hewson,
who first published on the lymphatics of birds, and who discovered their
lacteal absorbents, acknowledges that " it is but doing justice to the inge-
nious Mr. John Hunter to mention here that these lymphatics in the necks
of fowls were first discovered by him many years ago."   (Phil. Trans.,
1768, p. 220.)  And it appears from Dr. Monroes reply to Mr. Hewson,
that this discovery of Mr. Hunter's had been communicated to Dr. Cullen
by Dr.  George Fordyce,  and had  materially influenced Dr. Monro's
opinions respecting the absorbent system.
   Mr. Hewson also informs us, that prior to his  own publication  on the
Absorbent System of Amphibia, Mr.  Hunter had discovered and demon-
strated to him the chyle, and  we  must suppose  the  lacteal vessels, of a
crocodile.
   With respect to the absorbent system in fish, the discovery of this must
be awarded to  Mr. Hewson.
   As early as 1701 experiments had  been  instituted with a view  to dis-
cover the function of the lacteal vessels, indicated of  old by Erasistratus,
and rediscovered by Asellius.   Martin Lister and Musgrave satisfied them-
selves that coloured matter was  taken up  by these vessels which they
termed lacteal  veins,  from the  intestine.*  Nevertheless, until the obser-
vations and experiments of the Hunters, the lymphatics  generally were
believed by Haller and other physiologists to be simply continuations of
capillary or lymphatic arteries, and they were supposed to have no other
function than to carryback into the circulation the serum or lymph of the
blood.   Dr. William Hunter having observed that he could not inject the
lymphatics from the arteries excepting the injection were extravasated in
the cellular  substance, but that he could  readily  inject  the lymphatics
both from the common cellular substance and that which assists in form-
ing the parenchyma of the glands, as  the testis, spleen, &c.; observing
also  that the  course of the venereal  poison, when  introduced into the
system, indicated that it was  carried along by the lymphatics, affecting
the inguinal glands when applied to  the glans penis or prepuce,  and in
like manner affecting the glands of the armpits when  applied to the  hands,
and the  cervical glands when  communicated by the lips;   perceiving also
the close analogy of the lymphatics to the lacteal  absorbents, in their
valvular structure and mode of termination ; he concluded from all these
circumstances  that they had  an analogous function ; that they were not
reflected capillary arteries, but originated from all the interstices and cavi-
ties of the body, forming the  absorbing vessels of the general system, as
the lacteals were allowed to be of the alimentary canal.
   This doctrine was supported by the experiments of John Hunter given
in the text, which were first published in 1762, while he was abroad with
the army at Belleisle, by his brother,  Dr. William Hunter, in the Medical
Commentaries. It would seem, however, that Mr. Hunter did not consider
 these alone as sufficiently conclusive  to be submitted to the public, since
he left them in manuscript with his brother, who made use of them, four
years afterwards,  in the  controversial essay with  the  Monros, while John

   * [See Experiments for transmitting Blue-coloured Liquor into the Lacteals. Mus-
 grave, Phil. Trans., vol. xii.  p. 996.  Experiments for altering the Colour of the Chyle
in the Lacteal Veins, by M. Lister, Phil. Trans., vol. xiii., p. 6.  Powdered Blues pass
 into Lacteal Veins, ibid., vol. xxii., p. 819.]
                                   28 
314
HUNTER ON THE ANIMAL  CECONOMY.
was  abroad with the army at  Belleisle.   They were unaccompanied by
any additional proof or observations, but were considered by Dr.  William
Hunter as being decisive in depriving the veins of the power of absorb-
ing altogether.   Mr.  Hunter, however, continued  these  experiments in
other classes, as is shown in the following manuscript note in the posses-
sion of Mr. Clift. " The experiments upon the bird, to ascertain whether
the mesenteric veins  absorbed or not, were nearly the same with those
made upon the ass, in 1758, with musk, as also with spirits of wine ; and
although in  those researches I did  not  discover the  lacteals  in the bird,
yet I  discovered that the red veins in the  mesentery in them  most proba-
bly did not absorb, because I never could find any of the liquors which had
been thrown into the gut mixed with the blood of the veins of the mesentery ;
and which I look upon as one of  the first steps towards proving another
system."   Subsequent experiments, especially those of Tiedemann and
Gmelin, Meyer and Segalos, have shown that a power of absorption  can-
not be denied to the veins ; yet the  admission of this power, (which must
be granted on anatomical grounds to the veins of all invertebrate  animals,
and to some parts, probably, of the vertebrate, as  the eye and the brain,)
does not invalidate or diminish the credit due to  those experiments and
enlarged conceptions of the uses and anatomical relations of the lymphatics,
by which the true function  of these  vessels was  ascertained.  I say the
true function; for though it be admitted  that the  veins absorb, yet every
physiologist,*—with  the exception of one who has held the  sympathetic
nerve to be no nerve, and who, in the nineteenth century, denied  that rep-
tiles and fishes  had lymphatic vessels,—allows that  absorption, and the
effecting a certain change in the  nature of  the  absorbed  liquors are the
only functions which  the lymphatic vessels perform.
  I would here for the present willingly leave the  subject,  but that I feel
it incumbent upon me, in regard to the character of an author whose works
have  exercised so great and salutary an influence over the surgical profes-
sion, to show  that the charge of  imperfection and negligence* which has
been  cast upon  the Hunterian experiments,—whose want of exactness,
according to M. Majendie, can only be excused by the rude  state  in which
the art of physiological  experiment was  at the period when they were
made,—rests entirely on the culpable oversight of  the accuser.
  In  relating one of his experiments, Mr.  Hunter states : " Nov. 13, 1758,
I opened the abdomen of a living sheep, which  had eaten nothing for
some  days ; and upon exposing the intestines and  mesentery we  ob-
served the lacteals were  visible, but contained only a transparent watery
fluid."
  Is it conceivable that any succeeding physiologist would have ventured,
in his commentary on Mr. Hunter's experiments,  to object  to them, " be-

  * [" L'etat d'imperfection oil etait 1'art des experiences physiologiques a l'e'poque oil
J. Hunter a fait  celle-ci peut seul excuser ce celebre anatomiste  de n'avoir pas senti
combien il y manque de circonstances importantes pour que l'on puisse, en la suppo-
santexacte,  en tirer quelques consequences.   En effet,  pour que  cette  experience
put etre de quelque utilite il  faudrait savoir si I'animal  etaitajeun  lorsqu'on l'a
ouvert, ou s'll etait dans le travail de la digestion ; il  aurait fallut examiner l'etat des
lymphatiques au commencement de rexpenence ; etaient-ils ou n'etaient-ils  pas pleins
de chyle," &c.  And again," Hunter fait une fausse theorie sur I'une de fonctions les
plus importantes de la vie, il 1'etaie a peine de quelques experiences inexactes, et dans
tous  les cas insuffisantes."—Precis Eiementaire de  Physiologic (3me edA  torn ii.
nn 1QQ 901 1                                           v       ' 
OF  ABSORPTION BY VEINS.
315
cause the experimenter had neglected to notice whether the animal experi-
mented on  was full or fasting;  or whether the lacteals were or were not
distended with chyle ?"
  To give  a colour to this objection, all reference to the experiment above
quoted is avoided in the ' Precis Eiementaire;' but even in the very ex-
periment of which M. Majendie gives a mutilated version, Mr. Hunter
expressly premises that, " having exposed the intestines fully, he observed
the lacteals filled with a white liquor at the upper part of the gut and me-
sentery ; but in those that came from the ileon and colon the  liquor was
transparent."
  In the herbivorous quadruped, the sheep, in which Mr. Hunter employed
starch as the menstruum of the indigo, the  transparent watery nature  of
the contents of the lacteals was especially noted  before the colouring ma-
terial was thrown into the intestines: they were afterwards  observed to be
filled with  a fluid  of a fine blue colour.  And  yet M.  Majendie  (ibid.,
p. 210) would have us believe that no alteration had been observed; that the
lacteals were of the same blue  colour before the  injection of the  indigo
and starch  had been performed  as after.
   Whether, however, the coloured  matter had passed into the lacteals or
not, it could not, by the most careful and varied  experiments, be detected
in  the veins.    Great precaution was taken to ascertain that fact.  Since
the natural colour of the blood rendered  it difficult to perceive a change
of  hue, the contents of the veins were collected and suffered to coagulate,
in the expectation of the serum manifesting the  presence of the indigo;
but it had  not the least bluish tint.
   Warm milk was then  made to circulate from the artery into the vein;
and it might surely have been expected,  especially if the doctrine of non-
vital imbibition advocated by M. Majendie were true, to have then had a
trace of the coloured" contents of the  intestine in the venal milk; but no
such result took place.
   The experiment upon the ass, in which the  odour  of musk was  pre-
sent in the chyle, but not in the venous  blood, is  not  referred to  by M.
Majendie.
   In making these comments it is by no means  intended  to uphold the
infallibility of Mr. Hunter; but it  maybe safely averred that  a  candid
and careful perusal of his experiments on absorption, recorded in the text,
will not only exonerate him from any charge of haste or  negligence, but
must impress the unprejudiced reader with the conviction that those expe-
periments  have rarely been equalled and never excelled, either in  the in-
genuity and foresight manifested in their contrivance, in the skill and pre-
caution against error displayed during their performance,  in the fairness
of  the conclusions deduced from them,  or in  the minute accuracy and
candour which pervade their narration.
   To prove the  absorbent power  of the  lymphatics,  however,  is one
thing; that the veins  are thereby deprived of  the power of absorbing
altogether  is another;  and it is in reference to this latter question that the
experiments of M. Flandrin, recorded by M. Majendie, become interesting
to the physiologist.  But we may observe, en passant, that if M. Majendie
and his collaborates failed to obtain the  same results as Hunter from
similar experiments, other and as able experimenters in recent times have
been more successful.   Schroeder von   der Kolk, for example, filled a
loop of  intestine in a living dog with a  solution of the ferro-pcussiate  of 
316           HUNTER ON THE ANIMAL CECONOMY.
potass, and included the distended loop between two ligatures.   He then
placed the loop and its contents in a solution of sulphate of iron.   The
blue compound, which could be formed by no other means except by the
union of the two chemical fluids, was manifested in the lacteals  alone, and
not in the veins.  (Miiller's Physiologie, p. 229.)  Viridet and Mattei
also found that the chyle derived from yolk of egg was yellow,  while that
from food mixed with madder  was red.
  It is allowed indeed  by all physiologists,  and even  by M.  Majendie,
that the lacteals absorb the chyle.   But various experiments seem to show
that other fluids, and especially those of a poisonous nature, are taken up
from  the intestines by the  veins.  Such was  the general result  of the
numerous experiments of Tiedemann and Gmelin.*   Those related by
Majendie are not, however, free from objection.   He opened the abdomen
of a dog;  a loop  of intestine was  included  between two ligatures  and
separated  from  the  rest  of  the canal, all other connection between
the intestine and the  rest  of  the  body was destroyed except a single
mesenteric  artery and  vein.   Two  ounces  of  the  decoction of nux
vomica were  then injected into  the  detached portion of gut.  In six
minutes the effects of the poison manifested themselves with the ordinary
intensity.   Great precaution was taken to obviate  the  doubt which  any
lacteals remaining attached to the coats of the vessel might have occasioned;
but as this objection might still be urged, the following more  conclusive
experiment  was performed : a limb of a dog was amputated with the ex-
ception of a single artery and vein, which alone kept up the communica-
tion between the limb and the  trunk;  upas poison was then inserted into
the foot (enfonces dans lapatte).  Its effects became evident in less than
four minutes ; in  less  than  ten the animal was dead.   To  avoid the objec-
tion of invisible lymphatics in  the tissue of the vessels,  a segment of both
artery and vein was removed, after having substituted a portion of  quill,
so that there remained  no other communication between the limb and the
animal excepting by the  blood which  circulated from  one to  the other.
The poison introduced into the foot (introduit dans la patte) produced its
effects in about  four  minutes.  What makes it  so  evident, adds M.
Majendie, that the crural vein  was the sole medium of introduction to the
poison is this; that simple compression of this vessel arrested  the deadly
effects of the upas, which again immediately manifested themselves on  a
remission of the pressure.*
  Now, although the objection of lymphatics in the coats of the vessels is
obviated in this experiment, yet its conclusiveness may be questioned on
this ground, that the poison is  applied to a wound where  it can enter the
circulating fluids by open and  divided veins ;  but this is by no means the
condition which is understood in the theory  of venous absorption, which
relates only to an action attributed to the veins in their natural state, and
through the medium of their organic pores.  If this objection be invalidated
by  the experiment in which the decoction of nux vomica was  applied to
an  entire mucous surface, as when injected into the intestine, yet this may
be  accounted for by the paralyzing effects of the narcotic upon the animal
tissues with which it  comes in  contact:  it  may be  objected  that  their
vitality is destroyed, that inorganic imbibition then takes  place, and  that

  * [Versuche iiber die Wege auf welchem Substanzen aus dem Magen und  Darm
Kanal ins Blut  gelangen.]
   X [Loc. cit., p. 255, 256.] 
OF ABSORPTION BY VEINS.
317
the poison thus passes into the cavity of the vessels, and is carried along
the returning currents to the heart.
   But objections from the permeability of the tissue of a paralyzed vein
are endeavoured to be overcome by the assertion that all absorption is the
effect of non-vital imbibition, that  it is a property which the living animal
tissues possess in common with inorganic substances.
   Thus  M. Fodera having repeated the experiment of M.  Majendie and
Segalas, in  which the solution  of nux vomica was injected into the intes-
tine, afterwards incloses the same  poisonous  solution in a dead portion of
intestine, inserts this into a loop of the intestines of a living animal, and
from the effect produced by the transudation of the poison through the
parietes  of the dead intestine, and  through the paralyzed surface of that '
of the  animal experimented upon,  draws a sweeping conclusion as to the
nature of absorption in general.
   M. Majendie also rejects the  theory of the vital actions of the absorbents,
and strongly condemns the supposition of a selecting power  in absorbent
pores as gratuitous and unphilosophical.  He threw into the thorax of a
dog a  solution of nux vomica,  and he found that in proportion as the ob-
stacles to a free circulation were increased, by distending the blood-vessels
with warm  water, the effects of the poison on the system were retarded.
This  experiment is of the same species as that by M. Segalas, who limit-
ed the field of observation by confining the poison within a loop of intes-
tine, and interrupted the venous  current altogether by a ligature; it  is
consequently less conclusive, though liable to  the same objections.   When
M. Majendie removed the obstacles which he had imposed on the circula-
tion by opening a vein  and relieving  the  distended  vessels, the imbibed
solution  of nux vomica  rapidly produced its effects.   Thus the ordinary
laws of the living tissue being  suspended by  the application of a narcotic
or other poison to them, and  mechanical imbibition being  thereby per-
mitted,—or when similar poisons  are directly applied to divided vessels;
—it may be concluded, from the experiments above quoted, that whatever
arrests the return  of the empoisoned blood   to the heart,  whether atmo^
spheric  pressure, produced by  the action of  an  exhausted  cupping-glass,
 or by the direct pressure or ligature of the vein, or a general impediment
to the circulation  by a  plethoric  or artificial distension of  vessels, will
proportionately retard the deadly operations of the poison.   M. Majendie
 has also shown that the rapidity of its  action is increased  by artificially
diminishing the quantity of circulating fluids, and this  observation is of
great value  in a practical point of  view; but  much is still wanting to sus-
tain his  conclusion that the ordinary and natural absorbent processes are
arrested  by a  plethoric  or distended state of the  vessels,  and vice versa.
   The experiments by  which M. Majendie  endeavours to  support  the
theory of non-vital  imbibition or capillary  attraction as the  immediate
cause" of absorption are these:—A saturated  solution of nux vomica
applied  to the denuded vein of a living animal passes through the coats
of that vein into the circulation  and  kills.   The poison takes a longer
time  to  soak through the coats of  an artery ;  but having done so produces
the same deadly effect.   (Loc.  cit., pp. 279,  280.)  The nux vomica had
certainly affected the system by transuding through the coats of the vessels,
for its bitter taste could be detected in the  blood  which  adhered to the
 inside of the coat of the paralysed vessels.  Dead vessels and  animal
 membranes exhibited the same permeability  as those which M. Majendie
                                  28* 
318           HUNTER ON THE ANIMAL CECONOMY.
imagines to have retained their vital properties unchanged after  four or
ten minutes' contact with the narcotic  extract.   Ink injected  into the
serous cavities of the body of a living animal stains the lining membrane
and contiguous parts, (p. 282.)
  From  these experiments  the  author  concludes,  " II  me  parait  done
hors de doute que tous les vaisseaux sanguins, arteriels et veineux, morts
ou vivans, gros ou petits, presentent, dans  leurs parois,  une propnete
physique propre a rendre parfaitement raisondes principaux phenomenes
de l'absorption."—Ibid.
  To be consistent in this application of the theory of physical imbibition
to the actions of organized bodies, we ought to conclude, from observing
the serum transuded after death into the  pericardium, that such was the
condition in  the  living state  of the parts ; and a physiologist could  no
longer infer from  the different appearance of the  parts in the immediate
proximity of the gall-bladder, when examined in  a living and dead animal,
that the condition of the  coats of that receptacle as to permeability must
be influenced by the two states; and that  the living tissue  resists the
percolation which  the dead membrane readily allows.   M. Majendie is,
in fact, compelled by his theory to  deny such  difference ;  " the  bile,"
says he,  " does transude  through the coats of the living gall-bladder, but
the sanguineous current which exists in  the  small vessels which form in
great measure those parietes,  carries  it off in proportion as it  transudes."
Yet the same currents in the serous membranes, which at p. 258 he admits
are more abundant in vessels than  the  mucous, have no such effect in
preventing the passage of the ink, &c.
  But it is evident that he is  himself not satisfied with  his  explanation,
for in an account of one  of the  Hunterian experiments, in which  means
were adopted to ascertain whether water  injected into the intestine of a
living animal would be absorbed  by the vein, M. Majendie observes that
the vital action of the vein might be interrupted by the ligature of its cor-
responding artery.  Now this objection ought  to have no weight if, as
he supposes, the veins absorb  by a property of simple inorganic imbibition
with which their coats  are endowed.   But laying aside for a moment the
consideration of experiments,  in all of which the  vital operations are more
or less interrupted, and the parts in question forced  into  unnatural  condi-
tions, let us attentively consider  those phaenomena of absorption which
Nature  plainly puts before  our eyes.  The chyle is known to contain
globules of a definite size and form.  It  is admitted  by M. Majendie that
this fluid is exclusively taken up by the  lacteal absorbents.   The escape
of the lacteal  globules from the intestine could not be accounted for  on the
theory of imbibition or  permeability of tissue; organic pores must be
supposed to exist of a size adequate  to their transmission.   These  pores
have been described by Cruikshank  as  they were  seen  by  himself and
Dr. Wm. Hunter  in the human  subject; they have been witnessed by
Majendie in a dog.  But, says Majendie, it is unphilosophical, a  mere
physiological romance, to suppose that they can  act in any way different
from dead animal tissues; physical imbibition, inorganic capillary  attrac-
tion is the only cause of the transmission of fluids through animal mem-
branes that we are acquainted with, &c.  Yet these organized pores of
the lacteal absorbents permit nothing to pass them,  according to his own
admission, except the chyle.
   Still it is contended  that this  must be  a mechanical  action, because
lacteal absorption has been observed to go on in a dog for two hours after 
ON THE GROWTH OF BONES.
319
death ; but what does this prove but that the automatic or involuntary
actions continue for a certain time after the sensorial  power is lost,—
after apparent death has ensued ?
  Thus the only natural absorbent process in the living body that we can
reason upon from the evidence afforded by the nature of the substance
absorbed, and the ascertained structure of the mechanism employed in its
absorption, is totally at variance with the theory  of  non-vital imbibition
as the cause of absorption, and can only be explained by a vital or organic
endowment of the parts concerned, whether it be  regarded as a power of
selection or mutual attraction,  or an action whose peculiar stimulus is  the
contact of chyle.
  The various phenomena of  excretory absorption, as it may be termed,
render the theory of the capillary attraction of the tissue, whether of veins
or lymphatics, as their cause, equally unsatisfactory.  A property of dead
matter cannot account for the rapid absorption of fat in disease ;  or of the
parts of muscles, &c, which,  from some accident to  a joint, have become
useless ; or of alveoli of shed teeth ; or of the parts which in the progress
of growth become inconveniently situated, as the  first deposit of osseou3
matter in long bones ; or of parts which, at  the conclusion of growth, are
equally inconveniently situated in regard to  some tumour or collection of
matter, the discharge of which is salutary  to the constitution, &c.  A
mere physical endowment of animal tissues ought always to be acting,
and acting in but one  way;  and we therefore conclude, with Hunter, that
these  various and partial operations of the lymphatics are affected by  the
vital actions of organic pores,  in a manner analogous to that which de-
termines in the lacteals  the exclusive absorption of chyle.]
31. EXPERIMENTS   AND  OBSERVATIONS   ON   THE
     GROWTH OF BONES, FROM THE PAPERS OF THE
     LATE MR. HUNTER.
[Published by Mr. (afterwards Sir Everard) Home, in the Second Volume of the Trans-
  actions of a Society for the Improvement of Medical and Chirurgical Knowledge.]
                         Read October 4,1798.

   Mr. Hunter's Observations on  the Growth of Bones have been
mentioned  in his lectures ever since the year 1772, the first year in
which he gave lectures, and have been since adopted by the prin-
cipal teachers of anatomy in London;  it was therefore natural for
me to suppose that they were  generally known.   In this, however,
I find I have been mistaken, since the present Professor of Anatomy
in Edinburgh, in a late publication, declares himself an advocate for
the doctrine of Du Hamel; and from what  he advances, it appears
that he was not at all  acquainted with Mr. Hunter's experiments
upon  this subject.
   Under these circumstances I lay before the Society Mr. Hunter's
experiments and observations,  that they may be made known to the
public*
  * [This record contains little more than a brief notice of the general results of
Mr. Hunter's Observations and Experiments on the Growth of Bone.] 
320           HUNTER ON THE ANIMAL CECONOMY.
   It was some time  anterior to  the year  1772  that Mr. Hunter
began to investigate this subject, and an account of the experiments
and observations was given  to  me to  copy in that year, as a part
of his future lectures.
   Du Hamel had published a very ingenious theory upon the growth
of bones, which he endeavoured to support by  experiments tending
to prove that  bones  grow  by the extension of their parts.   With
this doctrine Mr. Hunter was not satisfied, and instituted experiments
to determine the truth of Du Hamel's opinion.
   Mr. Hunter  began his experiments by feeding animals with mad-
der, which has a  property of tinging  with  a  red colour that part
only  of the bone which  is added while the animal is confined to this
particular food.*
   He fed two pigs with madder for a fortnight, and at the end  of
that period one of them  was  killed ; the bones, upon examination ex-
ternally,  had a red appearance ;  when sections  were made of them,
the exterior part was found to  be principally coloured, and the in-
terior was  much less tinged.

  * [This  effect of madder upon bone (first described in  England by Belchier,
Phil, Tr., vol. xxxix., 1736, p. 287), depends on the following chemical properties.
The colouring principle of the Rubia Tinclorum has a strong affinity to phosphate
of lime, which earth, if artificially precipitated from a solution of madder, carries
down with it the colouring matter in a state of  combination, which water does
not disturb.
   The colouring principle of madder is hardly soluble in water, but is readily and
abundantly soluble in albuminous fluids, and, consequently, when taken into the
system as food, it is carried along, dissolved in the serum of the circulating blood,
and is deposited, combined with  the  phosphate of lime,  wherever  that salt is
separated from the blood to  contribute to the increase or reparation of bone.
   There are still, however,  some  points connected with this subject to be deter-
mined before the reasoning from experiments with madder on the growth of bone
can have all the desirable exactness.  Whether, e. g. the colouring principle of
madder, after having been  precipitated from the blood  in  combination with the
phosphate of lime, remains in the bone until the  particles  of the earth are them-
selves removed,—or whether the colouring matter  may again be redissolved in
the serum of the blood circulating through the substance of the bone,—are ques-
tions  not yet definitively settled ;  but there is much reason for believing that the
colouring matter may be removed  without the earth with which  it had been com-
bined. Accordingly, although an inference may be safely drawn with respect to
the part of a growing bone which receives the accessions of osseous substance,
by observing the part which is coloured with madder, yet  we cannot so certainly
conclude that a superficial colourless layer, in  an animal killed after  remission of
the madder, is a new deposit, since it may be the old, from which the madder has
been removed, after having  been redissolved in the serum.
   That the madder " tinges with  a red colour that part only of the bone which is
added," as is stated in the text, is an assertion, not only unsupported by any physio-
logical reasoning, but directly in contradiction to Hunter's own statement, " that
any part of a bone which is already formed is capable of beino- dyed with madder,
though not so fast as the part that is forming."
   I may observe, incidentally, that the phenomena under consideration throw
light  upon the chemical condition under which phosphate of lime is  contained in
the living body.  Since the colouring principle of madder has no affinity for lime
or calcium alone, it is clear that the phosphate of lime is not contained in the
blood or the bones as phosphorus, oxygen, and calcium, but that it exists as a
binary compound, and is  mixed as phosphate of lime with the cartilage or animal
basis of the bones.] 
ON THE GROWTH  OF BONES.
321
  The other pig was allowed to live a fortnight longer, but had now
no madder in its food ; it was then  killed, and the exterior part of
the bones was found  of the natural colour, but the interior was red.
  He made many other  experiments of the same kind upon the in-
crease of the thickness of  the neck  and  head of  the  thigh  bone.
From thence it appeared that the addition of new matter was made
to the upper surface, and a proportional quantity of the old removed
from the lower, so as to keep the neck of the same form, and re-
latively  in its place.*
  To ascertain  that the  cylindrical bones are  not elongated, by
new matter being interposed in  the interstices of the old, he made
the following experiment:  he  bored two  holes in the tibia of a pig,
one  near the upper end, and the other near  the  lower;  the space
between the holes was  exactly  two inches: a  small leaden shot
was inserted into each  hole.   When  the bone had been increased
in its length by the growth of  the  animal, the pig was killed, and
the space  within the two shot was also exactly two inches.
  This experiment was repeated several times on different pigs, but
the space  between the  two shot was  never  increased during the
growth  of the bone.f

  * [Amongst the original drawings of the bones coloured by madder in the
Hunterian experiments,  besides those of the thigh-bone referred to  in the text,
there are  three which illustrate the mode and direction of  increase of  the lower
jaw, showing that the new bone is deposited in greatest proportion on  the upper
and posterior part of the  ascending ramus, by which the rest of the jaw  is pushed
forwards, while the bone is absorbed from the anterior part of the ramus, and thus
the sockets of the posterior grinders are gradually brought into line, with a free
space above for the teeth to come forth.  This mode of growth, with absorption
at the symphisis of the jaw, continues throughout life in the elephant, in which
new grinders are thus brought forwards into use in uninterrupted succession.
  The preparations of bones coloured with madder in the  Hunterian Collection
are as follows.  Nos. 190 to 201 inclusive, Physiological Series ; Nos. 742 to
751, Osteological Series.]
  f [Meckel has rightly  observed (supposing the above to be a correct statement
of Hunter's experiments on  this point), that they are invalidated by the careful
and numerous experiments of Duhamel, which prove that the middle portion of
the long bones does increase in length,  though in a less degree than the ex-
tremities.
  It is not easy to understand how the unqualified assertion came to be published,
6ince the  preparation and record of an experiment confirmatory of those made by
Duhamel are still preserved in the Hunterian Museum.
  The preparation  (No.  188, Physiological Series), is the left tarso-metatarsal
bone of a  common fowl, exhibiting two perforations at equal distances, two thirds
of a inch from the extremities of the bone.   The original record of the experiment
is preserved with the specimen.

   |    |        •'                                           I   I
  " The two extreme lines are the present length of the bone from the head of the
joint of the inner toe. The two inner lines are the length when cauterized. The
outer dots are the present distance or the holes cauterized.  The two inner dots
are the distance of these holes when cauterized;  so that  the bone between the
two holes has grown about two-eighths of an  inch, while the other parts have
grown half  an inch."—Physiological Catalogue, vol. i., p. 40.
  In another experiment, in which shots were inserted into the holes, the resuu
was spoiled by the  shots passing into the medullary cavity of the  bone, while 
322
HUNTER ON THE ANIMAL CECONOMY.
  Besides these experiments on the growth of bones, he made others,
to determine the process of their exfoliation.  He cauterized portions
of bone in the same way in several  different animals, so as to be
able to examine the bones in the different stages of this process, and
found that the earthy part of the living  bone  in  contact  with the
dead portion  was first absorbed ; afterwards  the animal mucilage
itself, so  as to form a groove between the  two,  which  became
deeper and deeper, till thedead bone  was entirely detached, the dead
portion itself having undergone no change.*
  From these experiments he  ascertained the changes which take
place in bones during  their  growth, and  the  readiness with which
the materials of bone are  absorbed ; and from these facts, laid  it
down as an established  principle, that the absorbents are the agents
by means of which the  bones, during  their growth, are modelled
as it were,  and kept of the same shape.
  Bones, according to  Mr.  Hunter's doctrine, grow  by two pro-
cesses going  on at the same time, and  assisting each other; the ar-
teries bring the supplies to the bone  for its increase ; the absorbents
at the same time are employed in removing portions of the old bone,
so as to give to the new  proper form.   By  these means the bone
becomes larger, without  having  any  material change  produced in
its external shape.f

the perforations became obliterated, as in  Duhamel's experiment with the ring
of wire, by the  deposition of new bone from  the periosteum.  The shots being
liberated from the osseous texture could no longer serve to indicate its growth.
The  subject of the experiment, the tarso-metatarsal bone of a fowl, is No. 188,
Physiological Series.  It is  remarkable  that there  is not  a single prepara-
tion of the long bone of a pig, exhibiting the experiments with shot alluded to in
the text.  The  notes of the experiments on the bones of fowls above mentioned
are in the hand-writing of Mr. Wm. Bell,  Mr. Hunter's talented artist and assist-
ant, and must therefore have been written  in or before the  year 1789, when Mr.
Bell  left England for the East Indies.]
  * [See Preparations Nos. 197 to 204 inclusive, Pathological Series.]
  f [The difference between the Hunterian theory of the growth of bone and that
of Duhamel will be readily appreciated by attending to the explanation given by
Duhamel of the phaenomena which he observed during his investigations on this
subject.  Let us, for  example, select from the number of his  ingenious and in-
structive  experiments, that in which he placed  a ring of silver wire round the
middle of the shaft of the thigh-bone of a young pigeon ; and found at a subse-
quent period the ring in the medullary cavity of the bone, instead of embracing
the exterior of the shaft, where he had placed it.  It need  scarcely be observed
that  the Hunterian physiologist would explain these facts by stating that the
arteries of the periosteum had deposited new bone on the external surface of the
ring, while the  absorbents had removed the old bone in contact with the internal
surface of the ring, by which its relations to the osseous  parietes of  the femur
became reversed. But this physiological view of the phaenomena, arising out of
a knowledge of the powers and actions of  great and important vascular systems
in the frame, was wholly unsuspected by  and  unknown to the predecessors of
Hunter.  Duhamel explains the facts on  mechanical principles ;  assuming that
the bony layers of the shaft of the thigh-bone were expanded by the interposition
of additional osseous matter, and that the layers were cut through  in this process
of expansion by the unyielding wire which he had placed around them.  All his
explanations bear the same mechanical character, in which processes of growth
are assumed which are negatived by observation; and they are frequently vitiated 
OF THE WOLF, JACKAL, AND DOG.           323
32.  OBSERVATIONS  TENDING  TO SHOW  THAT THE
      WOLF,  JACKAL, AND DOG,  ARE  ALL  OF THE
       SAME  SPECIES.

  The true distinction between different species  of animals must
ultimately, as appears to me, be gathered from their incapacity of
propagating with each other an  offspring capable again of continu-
ing itself by subsequent propagations :  thus the horse and ass beget
a mule capable of copulation,  but  incapable of begetting or  pro-
ducing offspring.  If it be true that the mule has been known to breed,
which must  be allowed to be  an extraordinary fact, it will by no
means be sufficient  to determine  the  horse  and  ass to  be of the
same species; indeed, from the copulation of mules being very
frequent, and the circumstance of their breeding very rare, I should
rather attribute it to a degree of monstrosity in the  organs of the
mule  which  conceived, as not  being  a mixture  of two  different
species,  but  merely those of either the mare or female ass.  This
is  not so far-fetched an idea,  when we  consider that some  true
species produce monsters, which are a mixture of both sexes, and
that  many  animals of distinct  sex are incapable of breeding  at
all.  If then we find Nature in its most perfect state deviating from
general principles,  why may it  not happen likewise  in the  produc-
tion of mules; so that sometimes a mule shall breed from  the cir-
cumstance of its being a monster respecting mules?
  The time of uterine gestation being the same in all the varieties
of every species of animals, it becomes a necessary circumstance
towards determining a species.
  The affinity between the fox, wolf, jackal, and several varieties
of the dog, in their external form and several of their properties, is
so striking, that they appear to be only  varieties of the same species.
The fox would seem to be further removed from the dog than either
the jackal or wolf, at least in disposition, being naturally  a solitary
animal, and neither so sociable  respecting its own species or man ;
from  which I should infer that it is only allied to the dog by being
of the same genus.   It is confidently asserted by many that the fox
breeds with the dog; but  this has not been accurately ascertained ;
if  it had, the inquiry would probably  have  been carried further;
and once breeding, according to what  we have said, does not  con-
stitute a  species ; this, however, is a part  I mean to investigate.  I
do  not know if, in a  wild state,  there ever is in the same country a

by overstrained analogies, as where, in explaining the process of union in a frac-
tured bone, he compares the periosteum to the  bark of trees.  But the numerous
experiments of Duhamel,a which are characterized by much  precision and in-
genuity, well merit the attention of the student of Physiology.]

  a [Sur le development et la crue des os.  Memoires de l'Acad. des Sciences.
Paris, 1742, p. 497 ; and 1743, p. 187.] 
324          HUNTER ON THE ANIMAL CECONOMY.
variety in any  species of animal,  but  am inclined to think there
never is; if so,  as both wolves and foxes inhabited this  country,
they cannot then be of the same species.
  Wolves, as also jackals, are found  in herds;  and the jackal  is
so little afraid of the human species, that, like a dog, it comes into
houses in search of food,  more like a  variety of the dog,  the con-
sequence of cultivation rather than of chance.  It would appear to
be much the most familiar of the two;  for we shall find that in its
readiness to copulate with the dog, and its familiarity with the dog
afterwards, it is somewhat different from  the wolf; however,  this
may depend on  accident.   The wolf  being an animal  well known
in Europe, the part of the world where  natural history is particu-
larly cultivated, some pains have been taken to ascertain  whether
or not it was of the same  species with the dog; but I believe it has
been hitherto considered as only belonging to the same genus.
  Accident often does as much for natural history as premeditated
plans, especially when Nature is left to  herself.  The first instance
of the dog and wolf  breeding in  this country seems to have been
about the year 1766.  A Pomeranian  bitch  of Mr. Brookes's, in
the New  Road, was lined only once by a wolf, and brought forth a
litter of nine healthy puppies.   The veracity of Mr. Brookes is not
to be doubted,  respecting the bitch having been lined by a wolf;
yet as it  was possible she might have been lined by some  common
dog without his knowledge, the fact was not, in that, clearly made
out; but  it has since been ascertained that the dog and wolf will
breed.  One of the above-mentioned litter was presented to  me by
Mr.  Brooks, who likewise informed me that others had been  pur-
chased by different noblemen and gentlemen,  and named Lord
Clanbrassil as  having bought a bitch puppy.  I reserved  mine for
the purpose of experiment; and from observation it appeared  that
its actions were not truly those of a dog, having more quickness of
attention to what passed, being more easily startled, as if particu-
larly apprehensive of danger, quicker  in transitions from one action
to another, being not  so ready to the call, and less docile.  From
these peculiarities it lost its life, having  been stoned to  death in the
streets for a mad dog.
   Hearing that Lord Clanbrassil's bitch had bred, Sir Joseph Banks
was so obliging as, at my request, to write to  his  Lordship,  who
sent the following account:
     « Sir,
   " About seventeen or eighteen  years ago, the late Lord Mon-
thermer and I  happened to see a dog-wolf at  Mr. Brookes's,  who
deals in  animals, and lives in New  Road.   The animal was re-
markably tame, and  it struck us, for that reason, that a breed
might be procured between him and a bitch.
   " We promised Mr. Brookes a  good  price for puppies  if he suc-
ceeded.  In about a year a bitch  produced nine, and Lord Mon-
thermer bought one; and I had another, which was a bitch.   Lord
Monthermer's died of fits in about two years : mine lived longer, and 
OF THE WOLF, JACKAL, AND DOG.
325
had puppies only once.  One I gave  to  Lord Pembroke, but what
became of it I do not remember.   It was granddaughter of the wolf
by the dam, and got by a large pointer of mine.
  " It might be considered that  Mr. Brookes's  word  was not suf-
ficient proof that the  puppies  were really got by the  wolf, but the
appearance of the animals, so totally different from  all  others of the
canine species, did not leave  a  doubt upon our minds; and I re-
member  Hans  Stanley, who  had  adopted  Buffon's  opinion, was
thoroughly convinced upon seeing mine.   The animals  had  the
shape of the wolf refined;  the fur long, but almost as fine as that
of the black fox.
  " I am afraid I  have trespassed  too much upon your time, and
will only beg you will be assured nothing can give me more  pleasure
than any opportunity of assuring you how truly
                                       " I am,  sir, &c.
     " Jan. 7,1787.                           "  Clanbrassil."
   Upon the supposition that Mr.  Brookes's bitch was not lined by a
dog, but by the wolf, which I think we have no reason to doubt, the
species of the wolf is ascertained; but choosing to trace this matter
still further, and hearing that  Lord Pembroke's  bitch had likewise
bred, I was desirous to know  the truth of it; and as his  lordship
was in France  I took the liberty of writing to  Lord  Herbert, and
received the following answer :
     " Sir,                      Wilton House, Dec. 20, 1786.
   " The half-bred wolf-bitch you allude  to was given, as I always
understood, to Lord Pembroke by Lord Clanbrassil.  She might,
perhaps, have been bought at Brookes's  by him.   She had four
litters, one of ten puppies, by a dog between a mastiff and a  bull-dog.
One of these was  given to Dr. Eyre, at Wells in Somersetshire, and
one to Mr. Bucketl at Stockbridge.   The second litter was of nine
puppies, some of which were  sent  to Ireland, but to whom I know
not.   This litter was by a different dog, but of the same "breed as the
first.   The third  litter was of eight puppies, by  a large mastiff.
Two of these were, 1 believe, sent to the present Duke of Queensberry.
The fourth litter consisted of seven puppies, two of  which were sent
to M. Cerjat, a gentleman who now resides at Lausanne in  Switzer-
land, and  is famous  for breaking  dogs  remarkably  well. These
two  puppies  were, however, naturally  so  wild and unruly, that
he found it impossible to break them.
   She died four years ago, and  the  following  inscription was put
over the place where  she is buried  in this garden, by Lord Pem-
broke's orders:
                        Here lies  Lupa,
                 whose grandmother was a wolf,
       whose father and grandfather  were dogs, and whose
           mother was half wolf and half dog.  She died
                  on  the 16th of October, 1782,
                        aged 12 years.
                              29 
326
HUNTER ON THE ANIMAL CECONOMY.
   " I am sorry it is not in my power to give you any better account,
but if you think proper to write to Lord Pembroke, who is at rans,
I am convinced he will be  very happy  to give you any further in-
formation.
                                             " I  am, &c.
                                                   " Herbert."

   Buffon, whose remarks in natural history are well known, made
experiments to ascertain how far the  wolf and dog were ot the
same species, but without  success.   He says, " A  she-wolf, which
I kept three years, although shut up very young, and along with a
greyhound  of the same age, in a spacious yard, could not be brought
to agree with  it, nor endure  it, even when  she  was in heat,   bne
was the weakest, yet the  most mischievous, provoking, attacking,
and biting  the dog, which  at first  only defended itself,  but at last
killed her." And in another part of his work he makes the following
observation : " The dog, the  wolf, the fox, and the jackall, form .a
genus, of which the different  species are really so  nearly allied to
each other, and  of  which  the individuals  resemble each  other so
much, particularly by the internal structure and parts of generation,
that it is difficult to conceive  why they  do  not breed together."*
   This  part of  natural  history lay dormant, till Mr. Gough, who
sells birds  and has a collection of animals on Holborn-hill, repeated
the experiment on a wolf-bitch, which  was very tame, and had all
the actions of a dog under confinement.  A dog is the most proper
subject for  comparison, as we have opportunities of being  acquainted
with its disposition  and mode of expressing its sensations, which


   * In the Supplement to his Works he gives  the following  account which had
been sent to  him.  " A very young she-wolf, brought up at the Marquis of Spon-
tin's, at Namur,  had a dog, of nearly the same  age, kept with it as a companion.
For two years they were at liberty, coming and going about the apartments, the
kitchen, the  stables, &c, lying under the table, and upon the feet of those who
sat round it.  They lived in  the greatest familiarity.
   "The dog  was a strong greyhound.  The wolf was fed on milk for six months;
after that, raw meat was given her, which she preferred to that which was dressed.
When she ate no one durst approach her, but at other times people might do as
 they pleased, provided they did not use her ill.  At first she made much of all
the dogs which were brought to her, but afterwards she  gave  the  preference to
 her old companion, and from that time she became very fierce if any strange  dog ap-
 proached her.  She was lined for  the first time on the 25th of March ; this was
 frequently repeated while her heat continued, which was  sixteen days; and she
 littered the 6th of June, at eight o'clock in the morning ;  the period of gestation
 was therefore seventy-three days  at the most.*  She brought forth four young
 ones of a blackish  colour, some of whose feet, and a part of the breast, were
 white ; in this respect iaking after the dog, which was black and white.  From the
 time she littered she became surly, and set up her back at those who came neaT
 her; did not know her masters, and would even have killed the dog if it had been
 in her power."

    a This is  a longer period than in the bitch by at least ten days, but as the ac-
' count was made from the first time of her being lined, and she was in heat for a
 fortnight, and lined in that time, it is very probable, if the time was known when
 she conceived, that it would prove to be the same  period as in the dog. 
OF THE WOLF, JACKAL, AND DOG.
327
are most distinguishable in the motion of the ears and tail; such as
pricking up the  ears  when anxious, wishing, or  in expectation ;
depressing them  when  supplicant or in fear; raising the tail in
anger  or love, depressing it  in  fear, and moving it laterally in
friendship ; and likewise in raising the hair on the back from many
affections of the mind.  This  animal became in heat  in the month
of December 1785; and Mr. Gough having an idea of obtaining a
breed from wild animals, as monkies, leopards, &c, he was desirous
to have the wolf lined by some dog; but she would not allow any
dog to come  near her, probably from  being always  chained, and
not accustomed to be with dogs.   She was held, however, while a
greyhound dog lined  her, and they fastened  together exactly like
the dog and bitch.  While in conjunction she  remained pretty quiet,
but when at liberty endeavoured to fly at the  dog ; yet in this way
was twice lined.  She conceived, and brought forth four young
ones;  and though the time she went with young  was not exactly
known, it was believed to be the  same as  in the bitch.  Two  of
these puppies were like the dog in colour, who had large black spots
on a white ground ; another was of a black  colour ;  the  fourth  of
a kind  of dun, and would  probably have been like  the  mother.*
She took great care of them, yet did not seem very anxious when
one was taken from  her by  the keeper; nor did she seem afraid
when  strangers came into the room.  Unfortunately  these experi-
ments were carried no further: one of  the puppies being sold to a
gentleman, who carried it to the East Indies; and the other three,
one of which I was to have had, were killed by a leopard.   The
same wolf was in heat in December 1786,  and was lined several
times by a dog.   She pupped on the 24th of February  1787, and
had six puppies, one  of which, a bitch, I had, and kept it till it
was in heat; but missed the opportunity of having  her lined.  That
loss, however, was  made up  by a wolf-bitch belonging  to James
Syrnmons, Esq., of  Grosvenor-house,  Milbank:  the  history  of
which is as follows :
   This female wolf had been in his possession some time, had been
lined by a dog, and brought forth  several puppies, which I saw  in
company with Sir Joseph Banks, soon after Mr. Gough's  wolf, the
subject of my former  paper, had produced  her litter;  so that these
puppies were nearly of the same age with mine.   Mr. Syrnmons
reared them all;  but one only was a female, which more resembled
the mother or wolf kind than any of the others.  I communicated

  * [Here it may be observed, that, from the known  disposition of varieties to
revert to the original, it might have been  expected, on the supposition that the
wolf is the original of the dog, that the produce  of the  wolf and dog ought rather
to have resembled the supposed original than the variety.  In a litter lately ob-
tained, in the Royal Menagerie at Berlin, from a white pointer and a she-wolf,
two of the cubs resembled the common wolf-dog, but the third was like a pointer
with hanging ears.a]

   a [Lyell, Principles of Geology, vol. ii., p. 438, who cites  Wiegmann for this
fact.] 
328
HUNTER ON THE ANIMAL CECONOMY.
 to Mr. Syrnmons my wish that we should endeavour to prove the
 fact  of the wolf and  dog being of the  same species, by having
 either his female or mine lined  by a dog.  This  he very readily
 acceded to; and his bitch  received  the dog on the 16th, 17th, and
 18th  of December, 1788; and the 18th  of February following  she
 brought forth eight puppies, all of which she reared.
   If  we reckon from the  16th of December,  she  went  sixty-four
 days; but if we  reckon  from the 17th, the mean time, then it is
 sixty-three days, the usual time for a bitch to go with pup.   These
 puppies are the second remove from the wolf and  dog, and similar
 to that  given by my Lord  Clanbrassil to the Earl of Pembroke,
 which  likewise  bred again.   (See Philosophical Transactions,
 vol. Ixxvii., p. 255.)  It would have equally proved the same fact if
 she had been lined either by a wolf, a dog, or one of the males of
 her own litter.*
   It is remarkable that there seems to be only  one  time in the year
 in which impregnation is natural to the wolf, which is the month of
 December: for Mr. Gough's wolf has always  been in heat in that
 month ;  so was that of  Mr. Simmons.   The time of heat in his of
the half-breed (which is  nearly of the same age with mine)  corres-
ponded likewise with that of the  mother, and  of  those  bred from
Mr.  Gough's wolf.

                         OF THE  JACKAL.

   This animal  being so nearly allied to the dog, and only found
wild  like the wolf, I became desirous of ascertaining  of what par-
ticular  species it  was;  and while pursuing the subject, I was in-
formed that Captain Mears, of the  Royal Bishop, East Indiaman,
had brought home a bitch-jackal with young, which brought  forth
soon after his arrival; and that he had given the bitch-jackal  and
one puppy to Mr.  Bailey, bird-merchant, in Piccadilly.  I went to
see them, and purchased the puppy, the subject  of the following ex-
periment, which we found to have dispositions very similar to those
of the  half-bred wolf before-mentioned, which  I  had  from  Mr.
Brookes.

  * [This assertion, that the fertility of  a hybrid with  an individual of a pure
 breed proves the fact of identity of two supposed distinct species equally with
 the production of offspring from the connection of hybrid with hybrid, cannot be
admitted.  To prove the identity of two supposed distinct species, granting that
 the fertility of the hybrids from  the two  to be  the proof required, it should be
 shown that such hybrids are fertile inter se, and capable of propagatino- indefinitely
 an intermediate variety. Now this is precisely the fact which°is wanting in the
evidence adduced in the text.  All that Hunter proves is that two  species very
nearly allied to each other will produce a hybrid offspring, and that the hybrid is
 again productive with an individual of the  pure breed ;  but this only illustrates
 a general law  by which  the reversion of the hybrid  to the pure breed is provided
for ; while, on the other hand, the intermixture of the distinct species is guarded
 against by the aversion of the individuals composing them to sexual union : an
 aversion which we see in the case of Mr. Gough's female wolf to have been only
 overcome by force.] 
OF THE WOLF, JACKAL, AND DOG.           329
  To have a true history of this animal, I took the liberty of writing
to Mr. Mears, who politely called upon me, and, at my request, sent
me the particulars in a letter, of which the following is a copy :

     " Sir,
  " I had the honour of yours of the 15th instant;  and with regard
to the female-jackal, I can assure you that she took a small spaniel
dog of mine on board  my  ship, the Royal Bishop.  I had her,
when a cub, at Bombay ; and a  very  short time before I arrived in
England she got to heat, and enticed  this  small dog into the long-
boat, where I saw them repeatedly fast together.   I  brought her to
my house in the country,  where she pupped six puppies, one  of
which you  have seen.  Mr. Plaw, at  No.  90,  Tottenham-court
Road, has a dog-puppy, which will be at your service at any time
you chuse to send  for him, to make further experiments :  I called
on Mr. Plaw, and got his promise to let  you  have  the dog.
               " I have the honour to be, sir, &c.
                                              "Wm. Mears.
  " No. 107, Hatton-street, 16th Jan. 1786.
   " P. S.   I  had the bitch on board fourteen months. "

  Having taken this puppy  into the country, and chained it up near
a mastiff-dog, they  became very familiar, and seemingly  fond  of
each  other.   When the bitch  became  first in heat  I could not get a
proper dog: but about the latter end of September, she being again
in the same state, several dogs were procured and left with her.—
They  appeared indifferent about  her, probably  from being in a
strange place;  nor did she seem  inclined to  be familiar with them.
One of them  was a  large dog, which might not perhaps be able to
line  her;  but she was twice  tied by a terrier on  the 3d of Octo-
ber,  in a few weeks she was evidently bigger; and on the 30th
of November, in all fifty-nine days, brought forth five puppies.   A
few days  before this  period she dug a hole in the ground, by the
side of her kennel, in which she  littered; and it was some time be-
fore she would  allow the puppies to stay in the kennel when put
there.  Some of these began to  open  their eyelids in about eight,
others of them in nine days.
  Here then being an absolute proof of the jackal being a dog, and
the  wolf being equally made out  to be of the same species, it now
therefore  becomes a question whether the wolf is from the jackal,
or the jackal from the wolf (supposing them but one origin) ?   From
the  supposition that varieties become more tame in their nature
than  the originals,  we should be led to believe the  wolf to be the
original, and  that the jackal was a step towards civilization in that
species of animal, and that therefore the jackal should be considered
as a variety of the wolf.  There are wolves of various kinds, each
country having a kind peculiar to itself; but the jackals that I have
seen have been more uniform in resemblance to each other, proba-
bly because only to be found in one country, the  East Indies.  I
am  informed, however, that they vary  in size.  Whether the wolves
                              29* 
330          HUNTER ON THE ANIMAL CECONOMY.

of different  countries are of one species, or some of them only of
the same genus, I do not know;  but I should rather suppose them
to be all of one species.  An argument with me in favour of this sup-
position is, that if there were wolves of distinct species, we should
have  had by this time a great variety of every  species  of wolf,
with the various dispositions arising from variation in  other respects;
and those varieties would now have been turned to very useful pur-
poses, as in the case of the dog: for all the wolves we are yet ac-
quainted with should have naturally the principle of cultivation in
them (as much probably as any animal), as much at least as those
wolves we now know by the name of dogs.   The not  having a civil-
ized species with  all the characteristics of the wolf is, indeed, with
me a proof that they are all of the same species with the dog.  If
they are all of the same species with the dog, then the first variety
that took place would be still in the character  of a  wolf, differing
only in colour or some trivial circumstance, which could only arise
from a difference in  climate.   The wolf is naturally, I believe, the
inhabitant of cold climates, and little variety could take place while
it remained in such a situation; but if the jackal was originally  a
wolf,  which  had strayed by  accident more to the southward,  a
greater variation  from the genuine  character  might be produced,
the difference of climate, and perhaps of food, becoming causes of
variety.   By continuing to  inhabit a  warm  climate, this circum-
stance would in time lose part of its influence on the animal, and
the jackal would admit of little more variety.   This, however, is a
point not now to be determined, it being difficult (perhaps impossi-
ble) to say where the wolf became jackal, or (what we call) dog;
and, as dogs differ much from one another,  what  particular dog
may be  considered  as the first remove; or whether the  jackal is
the- intermediate link connecting the wolf and dog.   In any case we
may. reckon three great varieties  in this species, wolf, jackal, and
dog;  which again branch into their respective less obvious varieties.
If the dog proves to be the wolf tamed, the jackal may  probably be the
dog returned to ils'wild state;  which leads to another curious question:
Whether, as  animals vary  from climate, cultivation, or what may
be called differences in mode of living, they would  return to their
genuine character if allowed to go wild again in the original country ?
  To ascertain the original animal of a species, all  the varieties of
that species should be examined, to see how far they have the cha-
racter of the genus, and what resemblance they bear to  the other
species of the genus; for it is natural to suppose that the original
animal, or that which is nearest to  it, will have more of the true
character of the  genus, and a stronger resemblance to the species
nearest allied to  it, than  any  of the other varieties of its own
speciesi
   If we apply this to the dog, and  consider the fox as a distinct
species, which there is great reason  to believe it  is, that variety
which has the greatest resemblance to the fox is to  be looked upon
as  the  original of  all the others:  which  will prove  to be the
wolf. 
OF THE WOLF, JACKAL, AND DOG.
331
  Another mode of considering this subject, which is, however,
secondary to the above, is by supposing that all animals were at
first wild ; and therefore that those animals which remain wild are
the original stock • and that when we find animals far removed from
their originals in  appearance the  variation  takes place in conse-
quence of cultivation, yet so that we can still trace  the gradation.
What gives  some force to this idea  is, that where  the dogs have
been least cultivated, there they still retain most of their original
character, or similarity to  the wolf or the jackal, both in shape and
disposition.  The shepherd's  dog, all over the world, has strongly
the character of the  wolf or jackal; so that but little difference is
to be observed, except in size and hair.   That of size may perhaps
take place under a variety of circumstances ; but difference in hair
is in general, although not always, influenced  by climate.  Thus the
wolf has longer and softer  hair  than  the jackal, because a  more
northern animal; while the jackal  of the East, and  the shepherd's
dog  in  Portugal and Spain, have shorter and stronger hair than
those of  Germany or  Kamtschatka, from  inhabiting warmer
climates.  But when we consider their general shape, the character
of countenance, the quick manner, with the pricked and erect ears,
we must suppose them varieties of the same species.  The smelling
at the tail has been mentioned as characteristic  of the dog;  but I
believe it is  common to  most  animals, and only marks the male, for
it is the most certain way  the male has of knowing the female, and
by another  scent  discovering whether the  female  is disposed to
receive  the male, which  is perhaps the final intention.
   The Esquimaux dog, and   that  found among the Indians as far
south as  the Cherokees,  the shepherd's  dog  in Germany, called
Pomeranian, the shepherd's  dog in Portugal  and Spain, have all a
strong similarity to the wolf and jackal.
   Buffon, on the origin of dogs, seems to have had nearly the  same
idea : for he says the  shepherd's dog is the original  stock from
which the different kinds of dog have sprung.
   As the wolf turns  out to be a dog,  it  seems astonishing that there
was no  accountof dogs being found in  America.  But this I consi-
der as a  defect in the  first history  of that  country, as there are
wolves; and I must think, in spite  of all that has been said to the
contrary, that the Esquimaux and Indian dog is only  a variety from
a wolf of that country  which had  been tamed.  Mr. Cameron, of
Titchfield-street, who was many  years among the Cherokees, and
considerably to the westward of that country, observes that the dog
found there much  resembles the wolf, and that the natives consider
it to be a species of tame wolf; but as we come more among the
Europeans  who have settled there, the dogs are more  of  a mixed
breed.  Why the Cherokees  should have had only this kind of dog
transported among them, while every other part of America has the
varieties of Europe, is not easily solved.
   The  voice of animals is commonly characteristic  of the species;
but I should suppose it to be only characteristic of the original spe- 
332          HUNTER ON THE ANIMAL CECONOMY.

cies, and not always of the variety, and the supposition holds good
in the dog species.   Dogs may be  said to have a natural voice
and a  variation, arising  either from  a  variety  having taken
place in the species, or a kind of imitation.   It would appear that
the voice  of  the  wolf and  the  jackal  is  very  similar, being  the
natural voice, and is principally conveyed through the nose, and ex-
actly resembling that noise in dogs which is a mark of longing or me-
lancholy and also of fondness, but having no resemblance to the bark
of  the dog, which they do  not perform.   However, in catching a
jackal, when the animal found it  could not escape, it yelped like the
dog, which is  a  kind of barking,  and which is probably the natural
sound.   Barking is  peculiar  to  certain  varieties of the dog kind,
and even of those that bark some do it less than others: the dogs
in  the  South  Sea Islands do  not bark, our greyhound barks but
little, while the  mastiff and many of  the smaller tribe,  as spaniels,
are particularly noisy in this way.   There is reason to believe that
the frequency  of this noise  may  arise from imitation : for the dogs
in the South Sea Islands learn  to bark, the half-breed jackal barked,
and so did the half-breed wolf, although but little;  and others, as
the hound, have a peculiar  howl, by huntsmen called the tongue,
which noise, and the barking  also,  are both made by opening the
mouth.  A variety in the voice, or some parts of the voice, in varie-
ties of the same species, is not  peculiar to the dog.
  It is a curious circumstance that  variety not only takes place in
colour and form, from the change of habits in the parents, but that
the dispositions  are  also changed;  and that the dispositions are
most  commonly changed in such a way as appears best adapted to
the form of the animal.  The change in the habits of the parent
animal arise principally from its  connection with  the  human kind,
which has now  succeeded in training dogs  so as to fit them, both
in body and mind, for almost every purpose of human ceconomy, as
if man  himself  had formed them  expressly with such intention,
while at the same time  he can  only be considered as an occasional
cause, for we  may observe that all the males of the wolf kind  are
nearly the same, and  so are  likewise those of the jackal, having
little or no variety in  their dispositions.   Those of the  half-breed,
and even those that are three removes, although tame, yet have not
the  docility of dogs, nor are they so  immediately at the  command
of the human will;  neither are they  perfectly satisfied with  an arti-
ficial life, having when  left to  themselves a propensity to fall back
into their original instinctive principles.*

  *  [The range of deviation from the original type appears  to be greater in the
dog than in any other known species. Besides the well known and considerable
differences in the quantity, colour, and texture of the hair, and in the size, form,
and proportions of the body, in some individuals  an additional false grinder ap-
pears; and there is a race of dogs which have a supernumerary toe on the hind-
foot, with the corresponding tarsal bones ;a—a variety analogous to the Dorkintr
(or five-toed) fowl,  and to the six-fingered families of the human race.]
[Cuv. Disc. Prelim. Ossem. Fossiles, Ed. iv. torn, i., p. 205.] 
.OF THE WOLF, JACKAL, AND DOG.           333
  The following account from Mr. Jenner, of Berkeley, to whom I
gave a second remove, viz., three parts dog, is very descriptive of
this propensity:
  '* The little jackal-bitch  you gave me is grown a fine handsome
animal;  but she certainly does  not possess  the understanding of
common dogs.  She is easily lost when I take her out, and is quite
inattentive to a whistle.  She  is  more shy than a dog, and starts
frequently when a quick motion is made before her.  Of her inches
she is uncommonly fleet, much more so than any dog I ever saw.
She  can  turn a rabbit in the  field ; she  is fond  of stealing away
and lying about the  adjacent meadows, where her favourite amuse-
ment is hunting the field-mouse, which she catches in a particular
manner."
  As animals  are  known  to  produce young  which are  different
from  themselves in  colour, form,  and dispositions, arising from
what may be called the unnatural mode of life, it shows this curious
power of accommodation  in  the animal ceconomy, that although
education can produce no  change in the colour, form, or disposition
of the animal,  yet  it  is capable of producing  a principle which
becomes so  natural to the  animal that it shall beget young different
in colour* and form, and  so altered  in disposition as to  be more
easily trained up to  the offices in  which  they have  been usually
employed, and having these dispositions suitable to such change of
form.
   It also becomes a question, whether they would  not go back
again to their original state, if put into the situation of the original
from  whence they sprang; or acquire a form resembling  the ori-
ginal of that country where they are placed.   I do not conceive
that they must necessarily go back through the same changes;  but
I have some  reason to suppose  they would gradually return to a
resemblance of that original.f  And it would  be difficult  to prove
whether, in many of the gradations, they are progressive or retro-
grade.   But this is a subject that requires particular attention and
investigation, and  upon which, I hope, some time or other, to  be
able to throw more  light.

  * [This has recently been exemplified in the produce of a male and female
Dingo, or wild dog of  Australia, brought forth at  the  Zoological Gardens, and
under circumstances which precluded the possibility of connection between the
female and any other dog than the male with which she was kept confined. Two,
out of the litter of five puppies brought forth, had the uniform red-brown colour
of the parents, the rest were more or less pied, brown and white.]
  ■J- [If the wolf were actually the original of the dog, it might have been expected
that the Dingo of Australia, supposing  it to have  originated from some dog ac-
cidentally introduced into that  continent, would have been found reverted to its
original condition, or as a wolf.  But there appears to have been no further pro-
gress towards the acquisition of the characters of the wolf, in this instance, than
may be supposed, on the theory of reversion, to have taken place in  the time of
Cook.  The existence of wild dogs  which are not wolves, as the Dingo of Aus-
tralia and the Dhole of India, which have either lost or have never acquired the
common character of domestication, variety of colour, is itself a strong argument
against the original of the domestic  dog ever having been a wolf.] 
334          HUNTER ON THE ANIMAL CECONOMY.
33.  OBSERVATIONS  ON THE STRUCTURE AND  CECO-
 NOMY OF WHALES. BY JOHN HUNTER, ESQ., F.R.S.*

  The animals which inhabit the sea are  much  less known to us
than those found upon land;  and the ceconomy of those with which
we  are best acquainted is much  less understood ; we are, therefore,
too  often obliged to reason from analogy where information fails,
which must probably ever continue to be the case, from our  unfit-
ness to pursue our  researches in the unfathomable waters.
  This unfitness does not arise from that part of our ceconomy on
which life and its functions depend, for the tribe of animals which
is to be  the subject of this  Paper  has, in that  respect, the  same
ceconomy as man,  but from a difference in the mechanism by which
our progressive motion is produced.
  The anatomy of the larger  marine  animals, when  they are
procured in a proper state,  can  be as well ascertained  as  that of
any others, dead structure  being  readily investigated.   But even
such opportunities  too  seldom  occur, because  those animals are
only to  be found in distant seas, which no one explores in pursuit
of natural history;  neither  can  they be  brought to us  alive from
thence,  which prevents our  receiving their bodies in a state fit for
dissection.  As they cannot  live in air, we are unable  to procure
them alive.
  Some of these aquatic animals  yielding substances which have
become articles of traffic, and in quantity sufficient  to render them
valuable as objects of profit, are sought after for that purpose; but
gain being the primary view, the researches  of the Naturalist are
only considered as  secondary points, if considered  at all.  At the
best our opportunities of examining such  animals do not  often occur
till  the parts are in such a state as to defeat the purposes of accurate
inquiry, and even these occasions  are so rare as  to prevent our
being able to  supply, by a second dissection, what was deficient  in
a first.  The  parts  of such  animals  being formed  on  so  large a
scale, is another cause which prevents any great degree of accuracy
in their  examination, more especially when it is considered how very
inconvenient for accurate dissections  are barges,  open fields, and
such places as  are fit to receive animals or parts  of such vast
 bulk.                                       F
  As the opportunities of ascertaining the anatomical structure  of
large marine animals  are  generally accidental,  I  have availed
myself as much as possible of all that have occurred ; and, anxious
to get more extensive information, engaged  a surgeon, at  a con-
 siderable expense,  to make  a voyage to  Greenland, in  one of the
ships employed in the whale fishery,  and furnished him with  such
necessaries as I thought might be requisite for examining and pre.

 *  [Originally published in  the Philosophical Transactions, vol. Ixxvii. 1787.] 
           OBSERVATIONS ON THE  STRUCTURE, ETC.        335

serving  the  more  interesting parts,  and  with  instructions  for
making general observations; but the only return I received for
this expense was a piece of whale's skin, with some small animals
sticking upon  it.   From  the opportunities which I have had of
examining different animals of this  order, I have gained  a tolera-
bly accurate idea of the anatomical  structure of some genera,  and
such  a  knowledge of the structure of  particular parts  of some
others,  as to  enable  me  to  ascertain  the  principles  of their
ceconomy.
   Those which  I have had  opportunities  of  examining  were the
following:
   Of the Delphinus Phoccena, or Porpoise, I have had several, both
male and female.
   Of  the  Grampus I have  had  two;  one  of them,  (Delphinus
Orca, Linn.  Tab. XLIV.)  twenty-four  feet long, the belly of  a
white colour, which terminated at once, the sides and back being
black; the other about eighteen feet  long, the belly white, but  less
so than in the former, and shaded off into  the dark colour of the
back.
   Of the Delphinus Delphis, or Bottle-nose whale (Tab. XLVI.), I
had one sent to me by Mr. Jenner, surgeon, at Berkeley.   It was
about eleven feet  long.
   I have also had one twenty-one feet long, resembling this last in
the shape of the head, but of a different genus, having only two teeth
in the lower jaw (Tab. XLVII.); the  belly was white, shaded off
into the dark colour of the back.   This species is described by
Dale  in his Antiquities of Harwich.  The  one  which  I examined
must  have been young, for I have a skull of the same  kind  nearly
three times as large, which must have belonged to an animal thirty
or forty feet long.
   Of the Balcena rostrata of Fabricius I had one seventeen feet long.
(Tab. XLVIII.)
   The Balcena Mysticetus, or large Whalebone whale, the Physeter
Macrocephalus, or Spermaceti whale, and the Monodon Monoceros,
or Nar-whale, have also fallen under my inspection.   Some of these
I have had opportunities of examining with accuracy, while others
I have only examined in part, the  animals having been  too long
kept before I procured them to admit of more than a very superficial
inspection.*

  * [Cuvier, in his masterly Chapter on existing Cetaceans (Ossem. Foss.,tom.
v. pt. i.), divides the Balaenae or true whales, (cetaceans having the roof of the
mouth furnished with  baleen or whalebone), into those which have, and those
which have not a dorsal fin.  Of the latter he admits but one species, frequenting
the northern latitudes, to be accurately defined, viz., the Balaena Mysticetus of
Linnaeus, and which Hunter, from the relative size of its baleen-plates terms the
' large whalebone whale.'  The species of Balaena found in the southern latitude
differs, according  to  Cuvier, from the Bal. Mysticetus, in having  all its cervical
vertebra? anchylosed, while in Bal. Mysticelus the five posterior cervical vertebrae
remain detached; and in the number of ribs, which are  thirteen pairs in the 
336            HUNTER ON THE ANIMAL CECONOMY.

   From these circumstances it will  be readily supposed  that  an
accurate description  of  all  the different  species  is not to be ex-
pected;  but  having  acquired a general  knowledge of the  whole

Bal. Mysticetus, and  fifteen  in  the Bal. Australis .■ there are also well-marked
differences in the form of the skull  in the two species.
   Of the fin-backed whales or Balxnopterx, Cuvier  considers the existence of
the species  without ventral  plicae, called gibbar or finfish, as reposing on more
than doubtful authority :  in the original figure by Martens (Voyage du Spitzberg,
1671), Cuvier  supposes  that  the  plicae  were accidentally omitted, rather than
absent in nature, since he finds that the skull of the so called gibbar, figured by
Camper, and its skeleton  figured by Albers (Icones ad Anat., Comp. illustr.),  are
identical with those of the Rorquals or Balxnopterx with the skin of the throat and
fore part of the abdomen disposed in longitudinal  folds.  Mr. Hunter had evi-
dently never met with a specimen  of the supposed gibbar, and, as he derived his
observations from Nature alone, he did not contribute towards perpetuating the
error of Martens, as most nomenclative naturalists and compilers  had done up to
his time, and continued to do until the publication of the works of Scoresby and
Cuvier.
   The principal characters by which the  Rorquals  (Balxnopterx)  differ from  the
Balaense,?iTe the greater flatness of  the head, the lower jaw projecting beyond  the
upper, the skin under the throat, chest, and anterior part of the abdomen longitu-
dinally plicated and  dilatable ; the  short  and  hard  baleen-plates, terminating
in stiff and brittle  bristles, a short and  thick fin  on the hinder region of the
back.
   Of the Balaenopterae which  frequent the northern latitudes three species have
been admitted into the Zoologists"  Catalogues, Balaenoptera Boops, Bal. musculus,
Bal. roslrata.   Cuvier submits these species to a criticism, severe, as usual, but
just; he  finds  that no two of the  species have ever been compared or  seen by
one naturalist, either  together or at different periods :  that the only appreciable
differences he can gather from the  best of their accounts resolve themselves into
those of size or degrees of mutilation of the dorsal fin : and he asks, " Qui oseroit,
d'apres l'observation d'individus vus isolement a de grandes distances de temps
et de lieux,  et par de personnes diverses, soutenir que ces differences ne venoient
pas de l'age 1"  Fabricius,  however, assigns three rows of low ridges on  the
upper part of the head,  extending forwards from the blow-holes, as a character
distinguishing  his Balaena Boops from Balaena rostrata: a more   important dis-
tinction is afforded by the number  of vertebrae.
   The Bal. musculus  attains,  according  to  Scoresby, the length of seventy or
eighty feet ; the Bal. Boops of the same author that of forty-six  feet.  The Bal.
rostrata of Fabricius  is  variously  described  as  seventeen,, twenty, and twenty-
five feet in length.
   The young Rorqual dissected by Hunter was  but seventeen feet long,  and he
accordingly refers it  to   the  Bal.  rostrata of Fabricius.  In speaking of it he
generally uses the term  applied by Sibbald to the species of which this  is sup-
posed by Cuvier to be the young, viz., 'piked whale;' and sometimes from the
relative size of the baleen plates, calls it 'small  whalebone whale,' in contradis-
tinction to the  'large whalebone whale,'  or Balaena mysticetus,■   not referring to
the relative  difference in the general bulk of the body, in which the ' small whale-
bone whale' (Balaenoplera Boops, Cuv )  has the advantage, since it attains the
length of from eighty to one hundred feet, while the ' large whalebone whale'
was never seen by Scoresby  to exceed the length  of sixty feet, nor was ever re-
ported to him to have been longer  than sixty-seven feet.
   The whale  described   by Dale, in  Taylor's Antiquities of Harwich (p. 411,
pi. xiv.), of which species Hunter dissected  an  individual, twenty-one  feet in
length, is generally called by him  the ' great bottle-nose whale,' in contradistinc-
tion to the Delphinus tursw, which he calls also 'bottle-nose,' or 'small bottle-
nose whale.'   Dale's whule is distinguished chiefly by the presence of only  two
small teeth  in the lower jaw, and a number of horny tooth-like projections from 
OBSERVATIONS ON THE  STRUCTURE, ETC.        337
 tribe  from  the different  species which have come under my ex-
 amination, I have  been  enabled to form  a tolerable idea, even of
 parts  which  I have only had  the opportunity of seeing  in a very
 cursory way.
   General observation would lead  us to believe that the whole of
 this tribe constitutes one order of animals, which  naturalists have
 subdivided  into  genera  and  species;  but  a  deficiency in  the
 knowledge of their  ceconomy has  prevented them from  making
 these  divisions with sufficient accuracy ; and this is not surprising,
 since  the genera and  species are still  in  some measure  undeter-
 mined, even  in animals with which we are better acquainted.
   The animals of this order are  in size the largest known, and
 probably, therefore, the fewest in number  of all  that live  in water.
 Size, I believe, in  those  animals which  feed  upon others, is in an
 inverse proportion to the number of the smaller; but I believe this
 tribe  varies  more in  that  respect  than any we know, viewing it
 from  the  whalebone whale, which is seventy or eighty feet long,*
 to the porpoise, that is five or six: however, if they differ as much
 among themselves as the  salmon does from the sprat, there is not
 that comparative difference in size that would at first appear.   The
 whalebone whale  is, I believe, the  largest;  the  spermaceti whale
 the  next  in size (the  one  which I examined,  although  not full
 grown, was about  sixty feet long); the grampus,  which is an exten-
 sive genus, is probably from  twenty to fifty feet long; under this
 denomination there is a number of species.

 the roof of the  mouth, which Cuvier conjectures may be  the rudiments or ana-
 logues  of the  baleen of the true whales. This Cetacean is now considered the
 type of a new genus, called by Lacepede ' Hyperoodon,'' and the only well-ascer-
 tained  species  is generally designated, after its original describer, Dale, ' Hype-
 roodon  Dalei.''   The  individual described  by Dale was fourteen feet in length.
 Another described by Chemnitz, which was captured at Spitzbergen, measured
 twenty-five feet.  A female, which was taken with her young one, near Harfleur,
 in 1788, was  twenty-three feet in length.  Nevertheless, the skeleton of the
 Hunterian specimen manifests all the characters of immature age, in the separation
 of the  epiphyses;  although it is to be observed that these parts are anchylosed
 less early in the Cetacea than in the land mammalia.
  The small bottle-nose whale of Hunter, is not the common dolphin, Delphinus
 delphis, L., as he supposed, but the  Delphinus Tursio of Fabricius, as is shown
 by the skull and other  parts which are preserved in  the Hunterian Collection, as
 well  as by the  size of the  specimen which Hunter describes.  The Delphinus
 delphis is from six to seven feet in length, and has from forty-two to forty-seven
 teeth on each side of each jaw.  The Delphinus Tursio attains the length often
 and eleven  feet, and has from twenty-one to twenty-three  teeth on each side of
 each  jaw;  which teeth are conical, but proportionally larger and more obtuse
 than in D. delphis.]
  * [This, as an average size, can only be attributed to the largest of the Balx-
 nopterx or fin-backed whales.  The usual length of the largest cachalots (Physeter
 macrocephalus, Shaw,) taken in the South Seas is about sixty-feet; but this size
 refers only  to the males, for there is a remarkable disproportion in the size of the
two sexes  in this  species of Cetacean, the full-grown female of which rarely
 exceeds thirty-five feet. The difference is principally in the length of the jaws,
 which are twice as long in the male as in the female, reminding one of the sexual
characters afforded by  the mandibles in the Lucani or stag-beetles.]
                                 30 
338          HUNTER ON THE  ANIMAL CECONOMY.
  From my want of knowledge of the different genera of this tribe
of animals, an incorrectness in  the application of the anatomical
account to the proper genus  may be the consequence; for when
they are of a certain  size they  are brought to us  as  porpoises;
when larger they are called grampus or fin-fish.   A tolerably cor-
rect anatomical description of each  species, with  an accurate
drawing of the external form,  would lead us to a knowledge of the
different genera, and the species in each ; and,  in order to forward
so useful a work, I propose, at some future period, to lay before the
Society descriptions and drawings of those which have come under
my own observation.
  From some circumstances  in their  digestive organs we should
be led to  suppose  that  they were nearly allied to each other, and
that there was  not the same variety  in this respect  as  in land
animals.
  In the description of this order of animals I shall always keep in
view  their analogy to  land animals, and to such as occasionally
inhabit the water, as white bears, seals, manatees,* &c, with  the
differences that  occur.   This mode of-referring them to other
animals better known will assist the mind in understanding the pre-
sent subject.   It is not, however, intended in this  paper to give a
particular account of the structure of all the animals of this order
which I have had  an opportunity of examining: I propose at pre-
sent chiefly to confine myself to  general principles, giving the great
outlines as far as  I am  acquainted  with them, minuteness  being
only necessary in the investigation of particular parts.
  In my account I shall pay some attention to the relations of men
who have given facts without knowing their  causes, whenever I
find that  such facts  can be explained upon true principles of the
animal osconomy, but no further.
  This order of animals has nothing peculiar to fish, except living
in the same element, and being  endowed with  the same powers of
progressive motion as those fish that are intended to move with a
considerable velocity; for I believe that all that come to  the sur-
face of the water (which this order of animals must do) have con-
siderable  progressive motion; and  this reasoning we may apply
to birds, for  those   which soar  very high have  the greatest pro-
gressive motion.
  Although  inhabitants  of the  waters  they belong to  the same
class as quadrupeds, breathing air, being furnished with lungs and
all  the other  parts peculiar to the ceconomy of that class, and
having warm blood ;  for we make this general remark, that in the
different  classes of animals there  is never  any mixture of those
  * [The aquatic mammalia which Hunter includes under this name are associated
by Cuvier,  in consequence of the absence of hinder extremities, with the true
Cetacea.  They include the manatee of South  America (Manatus), the dno-ong
of the Indian Ocean and Red Sea (Halicore), and the manatee of the Arctic Seas
(Rytina).   They are all herbivorous, and differ  in many anatomical particulars
from the true cetacea,  which are the subjects of Hunter's observations ; connect-
ing  these mammalia with the quadrupeds of the Pachydermatous order.] 
           OBSERVATIONS ON THE STRUCTURE, ETC.        339

parts which  are essential to life, nor  in their different mode of
sensation.*
  I shall divide what is called the ceconomy of an animal:
  First, into those parts and  actions  which  respect its  internal
functions, and on which life immediately depends, as growth, waste,
repair, shifting or changing of parts, &c, the organs of respiration
and  secretion, in which we  may include the powers of propagating
the species.
  Secondly, into those parts and actions which respect external
objects, and  which  are variously  constructed, according  to the
kind of matter  with which  they are to  be connected, whence they
vary more than those of the  first  division.   These are the parts
for, progressive motion, the  organs of sense and the organs of diges-
tion ; all of which either  act upon, or are acted upon, by external
matter.
  This variation from external  causes in many instances influences
the shape of the whole, or particular parts,  even giving  a peculiar
form to some parts which belong to the first order of actions, as
the  heart, which in  this tribe, in the  seal, otter, &c, is flattened
because the chest is flattened for the purpose of swimming.  The
contents  of the  abdomen  are  not  only adapted to the external
form; but their direction in the cavity is, in some  instances, regu-
lated by it.   The anterior extremities,  or fins, although  formed of
distinct parts, in some degree similar to the anterior extremities of
some quadrupeds, being composed of similar bones placed  nearly
in the same manner, yet are so  formed  and  arranged as  to fit them
for  progressive motion in the water only.
  The external form  of this order of animals is such as fits them
for  dividing the water in progressive motion, and gives them power
to produce that motion in  the  same manner  as those fish which
move with a considerable velocity.  On account of their  inhabiting
the water, their external  form   is  more uniform than in animals of
the  same class which live upon land; the surface of the earth on
which the progressive motion of the quadruped is to be performed
being various and irregular, while the water is  always the same.
  The form of the head or  anterior part of this order of animals is
commonly a cone, or an  inclined plane, except in  the spermaceti
whale, in  which it terminates in a blunt surface.   This form of head
increases  the surface of contact to the same  volume of water which
it removes, lessens the pressure, and is better calculated to bear the
resistance of the water through which the animal is to pass; probably
on this account the head is larger than in quadrupeds, having more
the  proportion observed  in  fish, and swelling  out  laterally at the

  *  [That is, there is never any combination of the modifications of vital organs
characteristic of two different  classes of animals in the same  species, as of a
double heart of the mammal with the branchiae  of a fish  ; nor is the structure of
the organ of hearing, or of any other sense characteristic of a higher class of
vertebrata, ever combined with a modification  of the vital organs peculiar to a
lower class.] 
340           HUNTER ON THE ANIMAL  CECONOMY.
 articulation of the lower jaw.  This may probably be for the better
 catching their prey, as they have no motion of the head on the body,
 and this distance between the articulations of the jaw is somewhat
 similar to  the  swallow, goat-sucker, bat, &c, which  may also be
 accounted for  from their catching  their food in the  same manner
 as fish ; and this is rendered still  more probable, since  the form of
 the mouth varies according as they have or have not teeth.  There
 is, however, in the whale tribe more variety in the form  of the head
 than of any other part, as in the  whalebone, bottle-nose, and sper-
 maceti whales; though in this  last it  appears  to owe  its shape in
 some sort to the vast quantity of  spermaceti  lodged there, and not
 to be formed merely for the catching of its prey.  From the mode
 of their progressive motion  they have not the connexion between
 the head and body  that is called  the  neck, as that would have pro-
 duced an inequality inconvenient to  progressive motion.
   The  body behind the fins or shoulders diminishes gradually to the
 spreading of the tail; but the part beyond the opening of the  anus is
 to be considered as tail, although to  appearance it is a continuation
 of the body.   The  body itself is flattened laterally, and I believe the
 back is much sharper than the belly.
   The projecting  part, or tail, contains the  power that produces
 progressive motion and  moves  the  broad  termination, the  motion
 of which is similar to that of an oar in sculling a boat; it supersedes
 the necessity of posterior extremities, and  allows of the proper shape
 for swimming.   That the  form  may be preserved as  much  as pos-
 sible, we find that all the projecting  parts  found in land animals of
 the same class  are  either entirely  wanting, as the external ear; are
 placed internally, as the testicles ; or  are  spread  along under the
 skin, as the udder.
  The tail is flattened horizontally, which is contrary to that fish;*
 this position of tail  giving the direction  to the  animal in the pro-
 gressive motion of  the body.  I shall not pursue this  circumstance
 further  than to  apply it to those  purposes in the animal ceconomy
 for which this particular direction is intended.
  The two lateral fins,  which are analogous to  the  anterior ex-
 tremities in the quadruped, are commonly small, varying however
 in size,  and seem to serve as a kind of oars.
  To ascertain the  use  of  the fin  on  the  back is  probably not so
easy, as the large  whalebone and spermaceti whales have  it not;
one should otherwise conceive it is intended to preserve the  animal
from turning.
  I believe, like most animals, they are of a lighter colour on  their

  * [This difference in the position of the tail-fin relates chiefly to the difference
between the whale and fish in the mode  and amount of respiration; the warm-
blooded whale requiring a frequent ascent to the surface of the water to breathe
the air, which the  horizontal tail enables  it to do.   In the air-breathincr Ichthyo-
saurus, the presence of a pair of horizontal flattened posterior paddles,°for direct-
ing the snout to the surface of the water, enabled that extinct reptile to'have lunas
in combination with the vertical tail of the fish.]                       ° 
OBSERVATIONS ON THE STRUCTURE, ETC.       341
belly than on their back; in some they are entirely white on the
belly, and this white colour begins by a regular determined line, as
in the grampus, piked whale, &c.; in others, the white on the belly
is gradually shaded into the dark colour of the back, as in the por-
poise.  I have been informed that some of them are pied upwards
and downwards,* or  have the divisions of colour  in a  contrary
direction.
  The element in which they live renders certain parts which are
of importance in other animals useless in them, gives to some parts
a different action, and renders  others of less account.
  The puncta lachrymalia with  the  appendages, as the sac and
duct, are in  them unnecessary ; and the  secretion from the lachry-
mal gland is  not water, but mucus, as it also is in  the turtle; and
we may  suppose only in small quantity, the gland itself being small.
  The urinary bladder is  smaller than in quadrupeds, and indeed
there is not any apparent reason why whales should have one at alh
   The tongue is flat and but little projecting, as they neither have
voice nor require much action  of this part, in applying the food be-
tween the teeth for  the purpose of mastication or deglutition, being
nearly similar to fish in this respect as well as in their progressive
motion.
   In some particulars they differ as much from one another as any
two genera  of quadrupeds I am acquainted with.
  The larynx, size of trachea, and number of ribs differ exceedingly
The  caecum is only found in some of them.   The teeth in  some are
wanting.  The blow-holes are two in number in many, in  others
only one.  The whalebone and  spermaceti are peculiar to particular
genera;  all which  constitute great variations.  In  other respects
we find an uniformity, which would  appear  to be  independent of
their living and moving only in the water, as in the  stomach, liver,
parts of generation of both sexes, and  in the kidneys.   In these last,
however, I believe it depends in some degree upon their situation,
although  it is extended to  other animals, the cause of which I do
not understand.
  All animals have, I believe, a smell peculiar to themselves;  how
far this is connected with the other distinctions I do not know, our
organs not being able to distinguish with sufficient accuracy.
  The smell of animals of this  tribe  is  the  same with that of the
seal, but  not so strong, a kind of sour smell, which the  seal has
while alive; the  oil has the  same smell with  that of  the salmon,
herring, sprat, &c.
  The observations respecting the weight  of the flesh of animals
that swim, which I  published in my Observations on the (Economy
of certain parts of Animals,* are applicable to these also ; for the
flesh in this  tribe is  rather heavier than beef: two portions of mus-
cle of the same shape, one from the pseas muscle of the whale, the
  * [This irregular distribution of the dark and light shades is  remarkable in the
Phocxna Rissoana of Fred. Cuvier.]
  + r Pages 200, 281.]
   L                          30* 
342          HUNTER ON THE ANIMAL CECONOMY.
other of an ox, when weighed in air, were both exactly 502 grains ;
but weighed in water, the portion of the whale  was  four  grains
heavier than the other.   It is probable, therefore, that the necessary
equilibrium between the water and the animal is produced by the oil,
in addition to which the principal action of the tail is such as tends
either to raise them or  to keep them  suspended in the water, ac-
cording to the degree of force with which it acts.
   From the tail being horizontal, the motion of the animal,  when
impelled by it, is up and down: two advantages are gained by this,
it gives the necessary opportunity of breathing, and elevates them
in the water ; for every motion of the tail tends, as I said before, to
raise the animal;  and that this may  be  effected, the  greatest mo-
tion of the tail  is  downwards, those muscles  being very large,
making two ridges in the abdomen;  this motion  of the tail raises
the anterior extremity, which  always tends to keep  the body sus-
pended in the water..

                         Of the Bones.

   The bones alone, in many animals, when properly united into
what is called the skeleton, give the  general shape and character
of the animal.  Thus a quadruped is distinguished from a bird, and
even one quadruped  from another; it  only requiring a skin to be
thrown over the skeleton to make the species  known.  But this is
not so decidedly the case with this order of animals, for the skeleton
in  them   does not  give  us the true  shape.   An immense head, a
small neck, few ribs, and in many a  short sternum and no pelvis,
with a long spine terminating in a point, require more  than a skin
being laid over them to give  the regular  and  characteristic  form
of the animal.
   The bones of the anterior extremity give no idea of the shape of
a fin, the form of which depends wholly upon its  covering.  The
different parts of the skeleton are so inclosed, and the spaces between
the projecting parts are so filled up,  as  to be altogether concealed,
giving the animal externally an uniform and  elegant form, resem-
bling an insect enveloped in its chrysalis coat.
   The bones of the head are in  general so large as to render tho
cavity which contains the brain but  a  small  part of the  whole;
while in the human species and in birds this  cavity constitutes the
principal bulk of the head.  This is, perhaps,  most remarkable in
 the spermaceti whale; for, on a general view of  the  bones of the
 head, it is impossible to determine where the cavity of the skull lies
 till led to it by the foramen magnum occipitale.  The same remark
 is applicable to the large whalebone and bottle-nose  whale; but in
 the porpoise, where the  brain  is larger  in proportion to the size of
 the animal, the skull makes-the principal part of the head.
    Some  of the bones in one genus  differ from  those of another.
 The lower jaw is an  instance of this.  In the spermaceti and bottle-
 nose whales, the grampus, and the porpoise, the  lower jaws, espe- 
OBSERVATIONS ON  THE STRUCTURE,  ETC.        343
cially at the posterior ends, resemble each other;  but in both the
large and  small whalebone whales the shape differs  considerably.
The number of some particular bones varies likewise very much.
   The piked whale has seven vertebras in  the neck, twelve which
may  be reckoned to the back, and iwenty-seven  to the tail, making
forty-six in the whole.*
   In the porpoise there are five cervical vertebras, and  one common
to the neck and back, fourteen proper to the back, and thirty to the
tail;  making in the whole fifty-one.f
   The small bottle-nose whale, caught near Berkeley, in the number
of cervical vertebrae resembled  the porpoise: it  had  seventeen in
the back, and thirty-seven in the tail; in all sixty.J
   In the porpoise four of the vertebrae of the neck are  anchylosed  ;
and in every animal of this order which  I have examined the atlas
is by much the thickest, and seems to be made  up of two  joined
together, for the second cervical nerve passes through a foramen in
this vertebra.  There is no articulation for rotatory motion between
the first and second vertebras of the neck.
   The small bottle-nose whale had eighteen  ribs on  each side, the
porpoise sixteen.§   The ends of the ribs that have two articulations.
in the whole of this tribe,  I believe, are articulated with  the body
of the vertebrae above (or before) and with the transverse processes
below (or of the succeeding vertebra),  by the angles ; so that there
is one vertebra common to the neck and back.  In the large whale-
bone whale the first rib is  bifurcated, and consequently articulated
to two vertebras.
   The sternum is very flat in the  piked  whale, it is only one very
short bone;  and in the porpoise it is a good deal  longer.  In  the
small bottle-nose it is  composed  of  three  bones, and  is of some
  * [In the skeleton of the Balaena rostrata preserved in the Museum of the College
of Surgeons, there are  only eleven pairs cf  ribs, and two  or three vertebrae are
wanting at the extremity of the tail;  but the total number  of vertebra could not
have exceeded fifty.  In the Balxnoptera Boops the number of vertebrae exceeds
sixty ; there being seven cervical, fourteen dorsal, and from forty-one to forty-four
caudal vertebrae.  In the skeleton of this species, exhibited in the year 1827, in
London, at Charing-cross, sixty-two vertebrae were distinguishable, and two or
three more must have been concealed in the portion of the tail which had  been
preserved in situ.  There were fourteen pairs of ribs.  Cuvier, in the second edi-
tion of his  ' Lecons d'Anatomie  Comparee,' assigns sixty-five vertebrae to the
Balxnoptera Boops, of which fourteen are dorsal.  In the Balxna Mysticetus there
are forty-eight vertebrae, viz., seven cervical,  thirteen dorsal, and twenty-ei^ht
caudal.]
  t [In the skeletons which we have examined there are seven cervical vertebrae,
the six first being anchylosed, thirteen costal or dorsal, and forty-six lumbar and
caudal, making in all sixty-six.]
  X [In the Delphinus Tursio there are seven cervical, the two first being anchy-
losed, thirteen dorsal or costal vertebrae, correspondingwith the pairs of ribs, and
forty-three to the tail, making in all sixty-three vertebrae.]
  $ [We have never found  more than thirteen pairs of ribs in either the Delphinus
Tursio, or Phocxna communis.  In the Grampus there are seven cervical vertebrae,
twelve costal, and forty-four lumbar and caudal;  making in all sixty-three verte-
brae.  The Cachalot has sixty-one vertebrae, and fourteen pairs of  ribs.  The
number of ribs in Balxnoptera rostrata is eleven pairs.] 
344           HUNTER ON THE ANIMAL CECONOMY.
length.  In the piked whale the first rib, and in  the  porpoise the
three first, are articulated with the sternum.*
   As a contraction, corresponding to the neck in quadrupeds, would
have been improper in this order of animals, the vertebras of the
neck are thin, to make the distance between the head and shoulders
as short as possible;  and in the small bottle-nose whale are only six
in number, f
   The structure of the bones is similar to that of the bones of quad-
rupeds: they are composed of an animal substance, and an  earth
that is not animal; these seem only to  be mechanically mixed, or
rather the earth thrown into the interstices of the  animal  part.
In  the bones of fishes this does not seem to be the case, the  earth
in many fish being  so united with  the animal part as  to render
the  whole transparent, which  is not the case  when the animal
part is removed by steeping the  bone in caustic alkali; nor is the
animal part so transparent  when deprived of  the  earth.   The
bones are less  compact than those  of quadrupeds that are similar
to them.
   Their form somewhat resembles  wrhat takes place  in the  quad-
ruped, at  least in those whose  uses are similar,  as the vertebras,
ribs, and bones of the anterior extremities have their articulations
in part alike, although not in all of them.  The articulation of the
lower jaw, of the carpus, metacarpus, and fingers are exceptions.
The articulation of the lower jaw is not by  simple  contact either
single or double, joined by a capsular ligament, as in the quadruped,
but by a very thick intermediate substance of the ligamentous  kind,
so interwoven that its parts move on each other, in the interstices
of which  is an oil.   This thick matted substance  may answer the
same purpose as the double joint in  the quadruped.J
   The two fins are  analogous to the anterior extremities of the
quadruped, and are also somewhat  similar in construction.  A  fin
is composed  of a scapula, os humeri, ulna, radius, carpus, and  meta-
carpus, in which last may be included the fingers, because the number
of bones are those which might be  called fingers, although they are
not separated, but included in one general covering with the  meta-
carpus.  They  have  nothing analogous to  the  thumb,§  and the

  * [In our dissections we find five pairs of ribs articulated to the sternum in the
porpoise.  In  the Hyperoodon there are also five pairs of sternal ribs.   In the
piked whale (Bal. rostrata) the floating  extremities of the ten posterior pairs of
ribs are attached to strong ligamentous decussating bands, which form a middle
tendinous raphe, in the place of a sternum.]
  f [The true number of cervical vertebrae  is seven in all the carnivorous Cetacea,
as the holes for the transmission of the cervical nerves distinctly demonstrate.
In the  manatee there  are only six.  The more or less anchylosed condition of
these vertebrae gives fixity to the head.  The corresponding region of the spine in
fish is rendered inflexible; and in the burrowing armadillos some of the cervical
vertebrae are anchylosed, which structure in all these cases is designed to afford
the requisite power to the head for overcoming pressure.]
  X  [See the Preparation No. 240, Physiological Series, Hunterian Museum.]
  § [i e. No. digit  analogous in the opposable property which essentially charac-
terizes a thumh; but the homologous digit, the fifth on the radial side, is present 
OBSERVATIONS ON THE  STRUCTURE, ETC.
345
  number of bones in each is different: in the fore-finger there are
  five bones, in the middle and ring-finger seven, and in the little finger
  four.   The articulation  of  the  carpus, metacarpus,  and fingers  is
  different from that of the quadruped, not being  by capsular  liga-
  ment,  but by  intermediate cartilages  connected  to each bone.
  The cartilages  between  the different bones of the fingers  are of
  considerable  length, being nearly equal to one  half of that of the
  bone:  and this  construction of  the parts gives firmness with some
  degree of pliability to the whole.
    As this  order of animals  cannot be said to have a pelvis, they of
  course have no os  sacrum, and therefore the vertebras are continued
  on to the  end of the tail, but with  no distinction  between  those of
  the loins and tail.   But as those vertebras alone would not have had
  sufficient  surface to give rise to the muscles requisite  to the motion
  of the tail, there are bones  added  to the  fore part of some of the
  first vertebrae of the tail,* similar  to the spinal  processes  on the
  posterior surface.
    From all these  observations we  may infer that the structure,
  formation, arrangement, and the union of the bones which compose
  the forms  of parts  in this order of animals are much upon the same
  principle as in quadrupeds.
    The flesh of  muscles of this order of the  animals is red, resem-
  bling that  of  most  quadrupeds, perhaps more like that of the bull or
  horse than any other animal;  some of it  is very firm, and about
  the breast and belly it is mixed  with tendon.
    Although the body and tail is composed of a series of bones  con-
  nected together  and moved  as in fish, yet it  has its movement pro-
  duced by  long muscles, with long tendons, which  renders the body
  thicker while the tail at its stem is  smaller  than that of any other
  swimmer,  whose principal motion  is the same.  Why this mode of
  applying the moving powers should not have been used in fish is
  probably not so easily answered ; but in fish  the muscles of the body
  are of  nearly the same  length as the vertebras.
    The depressor muscles of the tail, which are similar in situation
  to the psoas, make  two very large ridges  on  the lower part of the
  cavity of the belly, rising much higher than the spine, and the lower
  part of aorta passes between them,
    These two  large muscles, instead of being  inserted into two  ex-

  in most cetacea.  It has two phalanges in the Porpoise, and four phalanges in the
  Black-fish (Delphinus  Globiceps).  It is wanting in the Balxnoptera Australis.]
   * [These bones protect the great vascular trunk below, as the upper processes
  protect the spinal chord above, the bodies of the vertebrae.  The former or inferior
.arches are termed by Geoffroy paraaux, or paravertebral elements; the latter the
 periaux, or perivertebral elements. I have proposed to denominate those which
 protect the vascular trunks ' aimapophyses ;' those which  protect the  nervous
 trunk ' neurapophyses.' The aimapophyses are articulated in the Cetacea at the
 interspaces of the bodies of the vertebrae, and connected with the intervertebral
 substance.   In the dorsal vertebrae of the tortoise, and in the sacrum of the ostrich,
 the neurapophyses, or  superior arches, are similarly placed with respect to the
 vertebral centres or bodies.] 
346
HUNTER ON THE ANIMAL  CECONOMY.
tremities as in the quadruped, go  to the tail, which  may be consi-
dered in this order of animals as the two  posterior extremities
united into one.                                        .
  Their muscles a  very short time  after death lose their fibrous
structure, become as uniform in texture as clay or dough, and even
softer.  This change is  not from putrefaction, as they continue to
be free from  any offensive smell, and is most remarkable in those
of the psoas muscles and those of the back.

                Of the Construction of the Tail.

  The mode  in which the tail is constructed is perhaps as beautiful,
as to the mechanism, as any part of the animal.  It is wholly com-
posed of three layers of tendinous fibres, covered  by the common
cutis and cuticle ; two of these layers are external, the other inter-
nal.   The direction of the fibres of the external layers is the same
as in the tail, forming a stratum about one-third  of an inch thick ;*
but varying in this respect  as  the tail is thicker or  thinner.  The
middle  layer is composed entirely of tendinous fibres, passing di-
rectly across, between the two external ones above described, their
length being  in proportion to the  thickness of the tail:  a structure
which gives amazing strength  to this part.
  The substance of  the tail is  so firm and compact that the  vessels
retain their dilated state even  when  cut  across; and  this section
consists  of a large vessel surrounded by as many small ones as  can
come in contact with its external surface: which of these are arteries
and  which veins I do not know.
  The fins are merely covered with  a strong  condensed  adipose
membrane.

                          Of the Fat.

  The fat of this order of animals, except the spermaceti, is what
we generally term oil.  It does not coagulate  in  our atmosphere,
and  is probably the most fluid  of  animal fats; but  the fat of every
different order of animals has not a peculiar degree of solidity, some
having it in the same state, as  the horse and bird.  What I believe
approaches nearest to spermaceti is the fat of ruminating animals,
called tallow.
  The fat  is differently situated in different orders  of animals, pro-
bably for particular purposes; at least  in  some we can assign  a
final intention.  In the animals which are the subject of the present
paper it is found principally on the outside of the muscles, imme-
diately under the skin, and is in considerable quantity.   It is rarely
to be met with in the interstices of the muscles,  or in any of the
cavities, such as the abdomen  or about the heart.
  In animals of the  same class living on land  the fat is more dif-
* [In the Bal. roslrata.] 
           OBSERVATIONS ON THE STRUCTURE, ETC.    •   347

 fused; it is situated, more especially when old, in the interstices of
 muscles,  even between the fasciculi of muscular fibres, and is
 attached  to many of the viscera; but many parts are free from fat,
 unless when diseased,  as the penis, scrotum, testicle, eyelid, liver,
 lungs, brain, spleen, &c.
   In fish, its situation is rather particular, and is most commonly in
 two modes:  in the one diffused through the whole body of the fish,
 as in  the salmon, herring, pilchard, sprat, &c.; in the  other, it is
 found in, the liver only, as  in all  of the  ray kind, cod,  and in  all
 those called  white-fish, there being none in any  other part of the
 body.* The  fat of fish  appears to be diffused through the substance
 of the parts which contain it, but is probably in  distinct cells.  In
 some of  these fish, where  it is diffused  over the  whole  body, it is
 more  in  some parts  than others, as on the belly of the salmon,
 where it is in larger quantity.
   The fat is differently inclosed in different orders of animals.  In
 the quadruped, those of the seal kind excepted, in the bird, amphibia,
 and in some fish, it is contained  in loose cellular membrane, as if
 in bags, composed of smaller ones, by which means the larger admit
 of motion on one  another and on their  connecting parts; which
 motion is in  a greater or less degree, as is proper or useful. Where
 motion could answer no purpose, as in the  bones, it is confined in
 still smaller  cells.   The fat is in a less degree in the  soles of the
 feet, palms of the  hands,  and in the breasts of many animals.  In
 this order of animals and the seal  kind, as far as I yet know, it is
 disposed of in two ways:  the  small quantity found in the cavities
 of the body  and interstices of parts is in  genera] disposed in the
 same way as in quadrupeds ; but  the external, which includes the
 principal part, is inclosed in a reticular membrane, apparently com-
 posed of fibres passing in  all directions, which seem to confine its
 extent, allowing it little or no motion on itself, the  whole  when dis-
 tended forming almost  a solid body.  This, however, is not always
 the case in every part of animals of this order ; for under the head,
 or what may be rather called neck, of the bottle-nose, the  fat is con-
 fined in larger cells, admitting of motion.   This reticular membrane
 is  very fine in some, and very strong and coarse in others, and even
 varies in different parts of  the same animal.   It is fine in the por-
 poise,  spermaceti,  and  large  whalebone  whale;  coarse in the
 grampus and small whalebone whale :f in all of them it is finest on
 the body,  becoming coarser towards the tail, which is composed of
 fibres without any fat,  which is also the case in the covering of the
 fins.  This reticular net-work in the seal is very coarse; and in
those which are not fat, when it collapses, it looks almost like a fine
net with small meshes.  This structure  confines  the animal to a

  * The sturgeon is, however, an exception, having its fat in particular situations,
and in the interstices of parts, as in other animals.
  f Where it is fine it yields the largest quantity of oil, and requires the least
boiling. 
348          HUNTER ON THE ANIMAL  CECONOMY.
determined shape, whereas in quadrupeds fat when in great quan-
tity destroys all shape.
  The fat differs in consistence in different animals, and in different
parts of the same animal, in which its situation is various.   In
quadrupeds some have the external fat softer than the internal, and
that inclosed in bones is softest nearer to their extremities.   Rumi-
nating animals have that species of fat  called tallow, and  in their
bones  they  have either hard fat, or marrow, or  fluid  fat, called
neat's-foot oil.  In this order  of animals  the internal fat is the least
fluid, and is nearly of the consistence of  hog's-lard ;  the external is
the common  train oil.  But the spermaceti whale differs from every
other animal I have examined, having the two kinds of fat just men-
tioned, and another, which is  totally different, called spermaceti, of
which I shall give a particular account.
  What is called spermaceti is  found everywhere in the  body in
small quantity, mixed with the common fat of the animal, bearing
a  very small proportion to the other fat.  In  the head  it is the
reverse,  for  there the quantity of spermaceti is large when com-
pared  to that of the oil, although they are mixed, as in the other
parts of the body.
  As the spermaceti is found in the largest quantity in the head,
and in what  would appear on a slight view to be the cavity of the
skull, from  a peculiarity  in  the  shape  of that  bone, it has been
imagined by  some to be the brain.
  These two kinds of fat in the head are contained in cells, or cel-
lular membrane, in the same manner as the fat in other animals;
but besides the common cells  there are larger ones, or ligamentous
partitions, going across, the better to support the vast load of oil of
which the bulk of the head is  principally made up.
   There are two places in the head where this oil lies ; these are
situated along its upper and lower part, between them pass the nos-
trils, and a vast number of tendons going to the nose and  different
parts of the head.
   The purest spermaceti is contained in the smallest and least liga-
mentous cells: it lies  above the nostril,  all along the upper part of
the  head, immediately under the  skin and common adipose mem-
brane.  These cells resemble  those which  contain the common  fat
in the other parts of the body nearest the skin.  That  which lies
above the roof of the mouth,  or between it and  the nostril, is more
intermixed with a ligamentous cellular membrane, and lies in cham-
bers whose  partitions are perpendicular.   These chambers are
smaller the nearer to the nose, becoming larger  and larger towards
the  back part of the head, where the spermaceti  is more pure.
   This spermaceti, when extracted cold, has a good deal the appear-
ance of the internal structure of a water-melon, and is  found in
rather solid lumps.
   About the nose, or anterior part of  the nostril, I discovered a
great many vessels, having  the  appearance of a plexus of veins,
some as large as a finger.  On examining them, I found they were 
            OBSERVATIONS ON THE STRUCTURE, ETC.        349

 loaded with the spermaceti and oil, and that some had correspond-
 ing arteries.   They  were most probably lymphatics ;*  therefore I
 should suppose that their contents had been absorbed from the cells
 of the  head.   We may the more readily suppose this from  finding
 many of the cells or  chambers almost empty; and as we may rea^
 sonably believe that this animal had been some time out of the seas
 in which it could procure proper food,  it had perhaps lived  on the
 superabundance of oil.
   The solid masses are what are brought home in casks for sperma-
 ceti.
   I found, by boiling this substance, that I could easily extract the
 spermaceti and oil which floated on the top from the cellular mem-
 brane.   When I  skimmed oft" the oily part, and let it stand to cool,
 I found that the  spermaceti  crystallized, and the whole became
 solid ;  and by  laying this cake upon any spongy substance, as chalk,
 or on a hollow body, the oil drained all off, leaving  the spermaceti
 pure and white.   These crystals were only attached to each other
 by edges, forming a spongy mass ; and by melting this pure sperma-
 ceti, and allowing it to crystallize, it was reduced  in appearance
 to half its bulk, the crystals being smaller and more blended, conse-
 quently less  distinct.
   The spermaceti mixes readily with other oils, while it is in a fluid
 state,  but  separates or crystallizes whenever it is cooled to a cer-
 tain degree, like two  different salts  being dissolved in water, one of
 which  will crystallize with a less degree of  evaporation  than  the
 other ;  or, if the water is warm and fully saturated, one of the salts
 will crystallize sooner than the other while the solution is cooling.
 I wanted to see whether spermaceti mixed  equally  well  with  the
 expressed oils of vegetables when warm, and likewise separated and
 crystallized when cold ;  and on trial there seemed to be no difference.
 When  very  much diluted with the oil, it is dissolved or melted by
 a much smaller  degree of heat than when alone; and this is the
 reason, perhaps, that  it is in a fluid  state in the living body.
   If the quantity of spermaceti is small in proportion to  the other
 oil, it is perhaps nearly  in that proportion longer in crystallizing;
 and when it does  crystallize, the crystals are much  smaller than
 those that are formed where the proportion of spermaceti is greater.
 From  the slowness with which the spermaceti crystallizes when
 much diluted with its oil, from a considerable quantity being to be
obtained in that way, and from its continuing for years  to crystal-
lize, one would be induced to think that perhaps the oil itself is con-
verted into spermaceti.
   It is most likely that if we could discover the exact form  of the
different crystals of oils, we should thence be able to ascertain both the
different sorts of vegetable oils, expressed and essential, and the dif-
ferent sorts of animal  oils, much better than by any other means ; in
the same manneras we know salts by theforms into which they  shoot

  * [See the Preparation No. 862, Physiological Series, Hunterian Museum.]
                               31 
350          HUNTER ON THE ANIMAL CECONOMY.
   The spermaceti does not become rancid or putrid nearly so soon
as the other animal oils, which is most probably owing to  the
spermaceti being for the most part in a solid state ; and  I  should
suppose that few oils would  become so soon rancid as they do if
they were always preserved in that degree of cold which rendered
them solid;  neither does this  oil become so soon putrid as the flesh
of the animal, and therefore, although the oil in the cells appeared
to be putrid before boiling, it  was sweet when deprived of the cel-
lular substance.  The spermaceti is rather heavier than the other oil.
  In  this animal  then we  find two sorts of oil, besides the deeper-
seated fat, common to all of this class, one of which crystallizes
with a much less degree of cold than the other,  and of course  re-
quires a greater degree of heat to melt it, and  forms, perhaps,  the
largest crystals of any expressed oil we know:  yet the fluid oil of
this animal will  crystallize in an extreme hard frost much sooner
than most essentia] oils, though not so soon as the expressed oils of
vegetables.  Camphire, however, is an exception, since it crystal-
lizes in our warmest weather, and when melted with expressed oil
of vegetables, if the oil is too  much saturated for that particular de-
gree of cold, crystallizes exactly like spermaceti.
  In the ox the tallow, and what is called neat's-foot oil, crystallize
in different degrees of cold.   The tallow  congeals with rather less
cold than the spermaceti,  but the  other  oil is similar to what is
called the train oil in the whale.
  I have endeavoured to  discover the form of the crystals  of dif-
ferent sorts  of oil, but could never  determine  exactly what that
was, because I could never find any of the crystals  single, and by
being always united the natural form was not distinct.
  It is  the  adipose covering from  ail of the whale kind that is
brought home in square pieces, called flitches, and which, by being
boiled, yields the oil on expression, leaving the cellular membrane.
When these flitches have become in some degree putrid, there issue
two sorts of oil; the first is pure, the last seems incorporated with
part of the animal  substance, which has become easy of solution
from  its putridity, forming a  kind of butter.   It is unctuous to  the
touch, ropy, coagulates, or becomes harder  by cold, swims upom
water, not being soluble in it; and the pure oil, separating in  the
same manner from this, swims above all.
  What remains after all the  oil is extricated retains a  good deal
of its form, is almost wholly convertible  into glue,  and is sold  for
that purpose.
  The cellular, or rather what should be  called the  uniting mem-
brane, in this order of animals is similar to that in the quadruped;
we find it uniting muscle to muscle, and muscle to  bone, for their
easy motion on one another.
  The cellular membrane, which is the receptacle for the oil near
the surface of the body, is in general very different from that in the
quadruped, as has been already observed". 
           OBSERVATIONS ON THE STRUCTURE, ETC.        351

                          Of the Skin.
  The covering of this order of animals consists of  a cuticle  and
cutis.
  The cuticle is somewhat similar to that on the sole of the foot in
the human species, and appears to be made up of a number of layers,
which separate by slight putrefaction; but this I  suspect arises in
some degree from there being a succession of cuticles formed.  It
has no degree of elasticity or toughness, but tears easily; nor do
its fibres appear to have  any particular direction.  The internal
stratum is tough and thick, and in the spermaceti whale its internal
surface, when separated from the  cutis, is  just like coarse velvet,
each pile standing firm in its place ;  but this is not  so distinguisha-
ble  in some of the  others, although it  appears  rough from the in-
numerable perforations.
  It is the  cuticle  that gives the colour to the animal; and in parts
that are dark I think I have seen a dirty-coloured substance washed
away in the separation of the cuticle from  the cutis, which must be
a kind of rete mucosum.
  The cutis in this tribe is extremely villous on  its external surface,
answering to the rough surface of the cuticle, and forming in some
parts small ridges, similar to those on the human fingers and  toes.
These villi are soft  and pliable; they float in water, and each is
longer or shorter,  according to the size of the animal.  In the sper-
maceti whale they were about a quarter of an inch long; in the
grampus, bottle nose, and piked whales, much shorter; in all,  they
are extremely vascular.
  The cutis seems to be the termination  of  the cellular membrane
of the body more closely united, having smaller interstices and  be-
coming more compact.*  This alteration in the texture is so sudden
as to make an evident distinction between what is solely connecting
membrane, and skin, and is most evident in lean  animals; for in
the change from fat to lean the skin does not undergo an alteration
equal to what takes place in the adipose membrane,  although it  may
be observed that the skin itself is diminished in thickness.  In fat
animals the  distinction  between skin  and  cellular membrane is
much less,  the gradation from the one to  the other  seeming to be
slower; for the cells of both membrane and skin being loaded  with
fat, the whole has  more the appearance of one uniform substance.
The uniformity of  the adipose membrane and skin is  most observ-
able in the whale,  seal, hog, and the human species, and is not only
visible in the raw, but in the dressed hides; for in dressed skins the
external is much more compact in texture than the inner surface,
and is in common very tough.
  * [That is to say, the denser external layer or dermis, and  the more open cel-
lular and fibrous  structure  below, which in the Cetacea is loaded with oil, are
essentially modifications of one and the same structure.  It is this  combination
of the dermal with the adipose tissues in the blubber of the whale which serves
to retain the internal heat, and at the same time resists the external pressure,
which must be occasionally enormous.] 
352          HUNTER ON THE ANIMAL CECONOMY.
   In some animals the cutis is extremely thick, and in some parts
much more so than in others ; where very thick it appears  to  be
intended as a defence against the violence of their own species or
other animals.  In most quadrupeds it is muscular, contracting  by
cold, and relaxing by heat.  Many  other stimulating  substances
make it contract,  but cold is probably that stimulus by which it was
intended to be generally affected.
   The skin is extremely elastic in the greatest number  of quadru-
peds, and in its contracted state may be said to be rather too small
for the body; by this elasticity it adapts itself to the changes which
are constantly taking place in the parts, and it is from the want of
it  that it becomes  too large in some old  animals.   In all animals it
is  more elastic in some parts than others, especially in those where
there is the greatest motion.  How far these variations take place
in  the whale I do not exactly  know ; but a loose elastic skin in this
tribe would appear to be improper as an  universal covering, con-
sidering the progressive motion of the animal, and the  medium in
which it moves; therefore  it  appears to  be  kept always  on the
stretch, by the adipose membrane being loaded with fat, which does
not allow the  skin  to recede when cut.   It is, however, more elastic
at  the setting on of the eyelids, round the opening of the  prepuce,
the nipples, the setting on of the fins, and under the  jaw,  to allow
of motion in those parts ;  and here there is more reticular, and less
adipose membrane.  But  in the piked whale there is probably one
of the most striking instances  of an elastic cuticular  contraction;
for though the whole skin of the fore part of the neck and  breast of
the animal,  as far  down as the middle of the belly, be extremely
elastic ; yet to render it still more so it is ribbed longitudinally, like
a  ribbed  stocking, which  gives an  increased lateral elasticity.
These ribs are, when contracted, about five-eighths of an inch broad,
covered with the common skin of the animal;  but in the  hollow
part of the rib it is of a softer  texture, with a thinner cuticle.   This
part is possessed of the greatest elasticity;  why it should  be  so
elastic is difficult to say, as it  covers the thorax, which can  never
be increased in size;  yet there must be some peculiar circumstance
in  the ceconomy of the species requiring this  structure, which we
as yet know nothing of.*
   The skin is intended for various  purposes.   It  is the  universal
covering given for the defence of all kinds of animals; and that it
might answer this purpose well,  it is the seat of one of the senses.j

 * [A strong and extensive  cutaneous muscle is intimately  connected with
the skin, but is  separated by a loose cellular texture from the deep-seated mus-
cles.]                                                 r
 f [The skin of the Cetacea has been made the subject of a special and minute
study by MM. Breschet and  Roussel de Vauzeme, who distinguish  in it, as in
that of other Mammalia, six chief constituents, which either  penetrate or are
superimposed upon one another, as follows:
  1. The derm or corium (le dermc), a dense fibrous cellular texture, which con-
tains and protects all  the other parts of the skin.  In the whale it is constantly
white and opake, and its peripheral surface presents a series of papillae, the 
OBSERVATIONS ON THE STRUCTURE, ETC.         353
                 Of the Mode of catching their Food.

   The  mouths  of animals are the  first parts  to  be  considered
 respecting  nourishment or food, and are  so much connected  with
 everything relative to it as not only to give good hints whether the
 food is  vegetable or animal, but also respecting the particular kind
 of either, especially of animal food.  The mouth  not only receives
 the food, but is the immediate instrument for catching it.   As it is
 a compound instrument in many animals, having parts of various
 constructions  belonging to it, I  shall at  present  consider it in this
 tribe no further than as connected with their mode of catching food,
 and adapting and disposing it for being swallowed.   It is probable
 that these animals do not  require either a division of the food, or a
 mastication of it in the  mouth,  but swallow  whatever  they catch
 whole ;  for we do not find any of them furnished with parts capable
 of producing either effect.  The mouth in most of this tribe  is well
 adapted for catching the  food; the jaws spread as they go back,
 making   the  mouth  proportionally  wider  than  in  many  other
 animals.
   There  is a  very  great variety in the formation  of the mouths


 intervals  of which  are  occupied by the epidermis,  which forms for each a
 6heath.
   2. The papillary bodies (les corps papillaires) consist of papillae covered by the
 derm.  They have a nacreous lustre, and are  several  lines  in length in the
 whale, but are much  shorter in the common dolphin and porpesse.  These pa-
 pillae are composed  of fibres penetrated by vessels ;  they originate from the
 subcutaneous nervous plexus,  and  return back again to  the same; the derm
 serves  merely as a sheath to the papillae, the extremities of which exercise the
 sense of touch.
   3. The  sudorific apparatus (Pappareil sudorifique)  consists of  soft, elastic,
 spiral canals, which extend through the entire thickness of the derm, and open
 in the intervals of the papillae by an orifice generally closed by a small epidermic
 valve.
   4. The inhalent apparatus (Pappareil d''inhalation) is  formed by extremely deli-
 cate canals, which are smooth,  straight, silvery, branched, and very easily rup-
 tured :  they originate in a plexus extended in the dermis beneath  the sudorific
 canals, anastomose together, and are provided with partitions.   The lymphatic
 vessels have no connection with these  canals, which communicate directly with
 the arteries and veins.  They are absorbing canals.
   5. The mucous  apparatus  (Pappareil blennogene).   This  is composed of
 secerning glands and  excretory ducts, which open between the papillae  like the
 orifices of the preceding canals. It is wholly contained  in the derm, and produces
 a mucous material, which by desiccation (or condensation) becomes the cuticle.
 In the whales this cuticle acquires an extreme thickness:  it is much thinner in
 the dolphins.a
  6.  The colorific  apparatus  (Pappareil chromatogene) is likewise composed of
 secerning glands and excretory ducts; it is situated in the first superior (pe-
 ripheral)' layers of the corium on the right and left   sides of the outlet of the
 excretory ducts  of  the preceding apparatus, and it pours  out the coloured pro-
 duct at  the  same  point where  the mucous  matter" is excreted, where  it
 stains it.]

   a [In the Cachalot  the external layer of cuticle is extremely fine, resembling
gold-beaters' skin.]
B                                 31* 
354          HUNTER ON THE ANIMAL CECONOMY.

of  this tribe  of animals,  which we have many opportunities of
knowing,  from  the head being  often  brought  home when  the
other parts of the  animal are rejected ; a circumstance which fre-
quently leaves  us  ignorant of the particular species to which it
belonged.
   Some catch their food by  means of teeth, which are in both jaws,
 as the porpoise and grampus;  in others, they are only in one jaw,
 as in the spermaceti  whale;* and in the large  bottle-nose whale,
described by Dale, there are only two small teeth in the anterior
part of the lower jaw.  In the  narwhale only two tusksf in the fore
part of the upper jaw :J  while  in some others there are none at all.
 In those which have teeth in both jaws, the number in each varies
 considerably; the  small bottle-nose had forty-six in the upper, and
 fifty in the lower;  and in the jaws of others  there are only five or
six in each.
   The teeth are not divisible  into different classes, as in quadrupeds;
but are all pointed teeth, and  are  commonly a good  deal similar.
Each tooth is a double cone, one point being fastened in the gum,
the other projecting: they  are, however, not  all  exactly  of this
shape.   In some species of porpoise the fang is flattened, and thin at
its extremity;  in  the spermaceti whale the body of  the  tooth is a
little curved  towards  the  back part of the mouth; this is also the
case in some others.   The teeth are composed of animal substance
and earth, similar to the bony part of  the  teeth in quadrupeds.
The upper teeth are  commonly worn down upon the  inside, the
lower on  the  outside; this-arises  from  the upper  jaw being in
general the largest.
   The situation of the teeth, when first  formed, and their progress
afterwards, as far  as  I have  been able  to observe, is  very different
in  common from those of the  quadruped.   In  the  quadruped the
teeth are formed  in the  jaw, almost surrounded by the alveoli, or
sockets, and  rise in the jaw  as they increase in length; the cover-
ing of the alveoli being absorbed, the alveoli afterwards  rise with
the teeth  ; covering  the  whole  fang; but in this tribe the teeth
appear to form in the  gum,§ upon  the edge of the jaw, and they

   * [The large exserted teeth are confined to the lower jaw in  this species, but
there are a few smaller teeth in the upper jaw of the cachalot.  They are de-
scribed by  Mr. F. D. Bennett (Zoological Proceedings, December, 1836,) as
sometimes occupying  the bottom of  the cavities which receive  the teeth of the
lower jaw, but  generally corresponding to the intervals  between  them.  They
measure in length about three inches, and are slightly curved backwards, are
developed in the gum, and have only a very slight  attachment to the jaw-bone;
in two instances, Mr. Bennett found  eight on each side of the upper jaw.]
   f [I call these tusks to distinguish them from common teeth. A tusk is that
 kind of tooth which has no bounds  set to its growth, excepting by abrasion, as
the tusk of the elephant, boar, sea-horse, manatee, &c.
  X [The  concealed  rudimental tusk in the  male narwhale  (ficmred  by Sir
Everard Home in the  Philosophical Transactions for 1813, p. 126),Avas first dis-
covered by  Tichonius, and described by  hirn in a dissertation entitled Monoceros
Piscis haudMonoceros, Copenhagen, 1706.]               •
  § [In the young porpesse the capsules and pulps of the teeth are always origi-
nilly imbedded  in the  substance of the gum, where the first development of the 
            OBSERVATIONS ON THE STRUCTURE, ETC.        355

either sink in the jaw as they lengthen, or the alveoli rise to inclose
them : this last is most probable, since the depth of the jaw is also
increased, so that the teeth appear to sink deeper and deeper in the
jaw.  This formation is readily discovered in jaws not full grown ;
tor the teeth increase in number as the  jaw lengthens,  as in other
animals.   The  posterior part  of  the jaw  becoming longer,  the
number of teeth in that  part  increases, the sockets becoming shal-
lower and shallower, and at  last being only  a slight depression.
   It would appear that  they  do not shed their teeth, nor have they
new ones formed similar to the old, as is the case with  most other
quadrupeds, and also with the alligator.   I have never been able to
detect young teeth under the roots of the old ones;  and indeed the
situation  in which they are first formed makes it in some degree
impossible, if the young  teeth follow the same rule in growing with
the original ones, as they probably do in  most animals.
   If it is true that the whale tribe  do  not shed their teeth, in what
way  are  they supplied  with  new ones corresponding in size with
the increased size of the jaw ?   It would  appear that the jaw, as  it
increases  posteriorly, decays  at  the  symphysis, and  while  the
growth is going on, there is a constant succession of new teeth, by
which means the new-formed teeth  are proportioned  to the jaw.
The same mode of growth is evident in  the elephant, and in some
degree in many fish; but in  these last the absorption  of the jaw is
from  the whole of the outside  along where  the teeth are placed.
The depth of the  alveoli seems to prove  this, being shallow at the
back part of the jaw, and becoming deeper towards the middle, where
they are the deepest, the teeth  there having  come to the full size.
From this forwards they are again becoming shallower, the teeth
being smaller, the sockets wasting, and at the symphysis there are
hardly any  sockets  at  all.  This  will make the exact  number  of
teeth in any species uncertain.
   Some genera of this  tribe have  another mode of catching their
food, and retaining it till swallowed, which  is by means of the sub-
stance called whalebone.   Of this there are two kinds known; one

tooth commences, by the formation of the crown.  In this structure we see the
analogy to the growth of whalebone, in which the base of the baleen-plates adhere
throughout life to the gum only.  A superficial or less scrupulous observer might
have been led to describe the development of the teeth of the Cetacea according
to the ordinary analogies ; but what are we to think of that writer who takes the
opportunity to correct (!) Hunter's original and just description of this point, by
informing his readers that the germs of the teeth are developed in an alveolar
cavity in other mammalia? and, who, in reference to the hypotheses suggested
by Hunter to account for the lodgment of the teeth of the Cetacea in sockets,
quotes only the first, for the purpose of contradicting it, asserting that the 'cavity
for the reception of the young teeth cannot be formed  by the sinking of the teeth
in it,' but avoids all mention  of the second hypothesis, which Hunter states to be
the most probable of the two, and which is the  true  one?  (See Knox, in the
Edinburgh Philosophical Transactions, vol. xi., p. 411.)  Rapp, however, seems
to adopt the first view; he says, the fangs of the teeth gro\v by degrees into the
groove of the jaav: ''Nach  und nach wachst dann  die Wurzel in Rinne des
Kiefers hinein."   Ceiaceen,  p. 127.] 
356
HUNTER ON THE ANIMAL CECONOMY.
very large, probably from the largest whale  yet  discovered ; the
other from a smaller species.*
  This whalebone, which is placed on the inside of the mouth, and
attached to the upper jaw, is one  of the most  singular circum-
stances  belonging to this species, as they have most other parts in
common with quadrupeds.   It is a substance, I  believe, peculiar to
the whale, and  of the same nature as horn, which I shall use as a
term to express what constitutes  hair, nails, claws, feathers, &c.;
it is wholly composed of animal substance, and extremely elastic.f
  Whalebone consists of thin plates of some breadth, and in some
of very  considerable length, their breadth and length in some degree
corresponding  to one another; and when longest they are com-
monly the broadest, but not always so.   These  plates are very dif-
ferent in size in different  parts of  the same mouth, more especially
in the large  whalebone  whale, whose  upper  jaw does not pass
parallel  upon  the  under, but makes an  arch, the semidiameter of
which is about  one-fourth of the length of the  jaw.   The head in
my possession is nineteen feet long, the semidiameter not quite five
feet: if  this proportion  is  preserved, those whales which have
whalebone fifteen feet long must be of an immense size.
  These plates are  placed in several rows, encompassing the outer
skirts of the upper jaw, similar to teeth  in other  animals.  They
stand parallel  to each other, having one edge towards the circum-
ference  of the mouth, the other towards the centre or cavity.
They are placed near together  in  the  piked  whale, not being a
quarter of an  inch asunder where  at  the greatest  distance, yet
differing in this respect in different parts  of the same mouth ; but in
the great whale the distances are more considerable.
   The outer row is composed of the longest  plates;  and these are
in proportion to the different distances between the two jaws, some
being fourteen or fifteen feet long, and twelve or fifteen inches broad;
but towards the anterior  and posterior part of the mouth, they are
very short; they rise for  half a  foot  or more,  nearly  of equal
breadths, and  afterwards shelve off from their inner side until they
come near to a point at the outer:  the exterior of the inner rows
are the longest, corresponding to the termination of the declivity of
the  outer, and  become  shorter and shorter till they  hardly rise
above the gum.
   The  inner rows are closer than the outer, and rise almost per-
pendicularly from the gum, being longitudinally straight, and have
less of the declivity than the outer.  The plates of the outer row
 laterally are not quite flat, but make a serpentine line; more espe-
 cially in the piked  whale the outer edge is thicker than  the inner.
 All round the line made  by their outer  edges, runs  a small white
 bead, which is formed along with the whalebone, and wears down
 with it.  The  smaller plates are nearly of an equal thickness upon
   * [The laroest  species of whale yet discovered is distinguished by the small-
 sized baleen-plates, and is the Balxnoptera Boops, a3 was before observed.]
   X From this it must appear that the term bone is an improper one. 
           OBSERVATIONS ON THE STRUCTURE, ETC.       357

both edges.  In all of them, the termination is in a kind of hair,  as
if the plate was split into  innumerable small parts, the  exterior
being the longest and strongest.
  The two sides of the mouth composed of these rows meet nearly
in a point at the tip of the jaw, and spread or recede latterally from
each other as they pass back ;  and at their posterior  ends, in the
piked whale, they make a sweep inwards, and come very near each
other, just before  the opening  of the  oesophagus.   In  the  piked
whale, there were above  three hundred in  the outer rows  on each
side of the mouth.  Each layer terminates in'an oblique  surface,
which obliquity inclines to the  roof  of  the mouth, answering
to   the gradual diminution of  their length;  so  that the  whole
surface composed of these terminations, forms one  plane  rising
gradually from the roof of the  mouth;  from this  obliquity of the
edge of the outer  row, we may  in some  measure  judge of the
extent of the whole base, but not exactly, as it makes a  hollow
curve, which increases the base.
  The whole surface resembles the skin of an animal covered with
strong hair, under which  surface the tongue  must immediately  lie
when the mouth is shut:  it is of a light  brown colour in the piked
whale, and is darker  in the large whale.
  In  the piked whale, when  the  mouth is  shut, the projecting
whalebone remains entirely on the inside of the lower jaw, the
two jaws meeting everywhere  along their surface ; But how this
is effected in the large whale I do not certainly know, the horizontal
plane made by the lower jaw being straight, as in the piked whale;
but the upper jaw, being an arch, cannot be  hid by the lower.   I
suppose  therefore  that  a  broad upper lip, meeting as  low  as
the lower jaw, covers the whole of the outer  edges of the  exterior
rows.
  The whalebone is  continually wearing down, and renewing in the
same proportion, except when the animal is growing it is renewed
faster and in proportion to the growth.
  The formation of the whalebone is extremely curious, being in one
respect similar to that  of the  hair, horns, spurs, &c. ; but it has
besides another mode of growth and decay equally singular.
  These  plates form  upon a thin  vascular  substance, not  imme-
diately adhering to the jaw-bone, but having a more dense substance
between, which is also vascular.   This substance, which  may  be
called the nidus  of the  whalebone, sends  out (the above) thin
broad  processes,  answering to each  plate,  on which the plate
is formed, as the cock's  spur, or the bull's  horn on the bony core,
or a tooth on its pulp ; so that each plate is  necessarily hollow at
its growing end, the  first  part of the growth taking  place  on the
inside of this hollow.
  Besides this mode  of growth, which is common to  all such sub-
stances,  it receives  additional  layers on  the outside, which are
formed upon  the above-mentioned vascular substance extended
along the surface of  the jaw.   This part also forms upon it a semi- 
358
HUNTER ON THE ANIMAL  CECONOMY.
horny substance between each  plate, which  is very white, rises
with the whalebone, and becomes even with the outer edge of the
jaw, and the termination of its outer part forms the  bead above-
mentioned.   This intermediate substance fills up the spaces between
the plates as high as the jaw, acts as  abutments to the whalebone,
or is similar to the  alveolar processes of the  teeth, keeping them
firm in their places.
  As both  the whalebone and  intermediate  substance  are con-
stantly  growing, and  as we  must suppose a determined length
necessary, a regular mode of decay  must be  established, not  de-
pending entirely on chance or the use it is put to.
  In its  growth three parts appear to  be formed :  one from  the
rising core,  which is the centre; a second  on the outside ; and a
third,being the intermediate substance.  These appear to have three
stages  of duration;  for that which  forms on  the  core I believe
makes  the hair, and that on the outside makes  principally the plate
of whalebone;  this,  when got a certain length, breaks off, leaving
the hair projecting, becoming  at the termination very brittle; and
the third, or intermediate substance, by the time it rises as high as
the edge of the skin of the jaw, decays and softens away like the
old cuticle of the sole of the foot when steeped in water.*
  The use of the whalebone, I should believe, is principally for the
retention of the food  till swallowed, and  do suppose the fish they
catch are small when compared  with the size of the mouth.
  The oesophagus, as in other animals, begins at the fauces, or pos-
terior part of the mouth; and, although circular at this part, is soon
divided into two passages by the epiglottis passing across it, as will
be  described hereafter.  Below  its  attachment  to  the trachea, it
passes  down in the posterior  mediastinum, at some  distance from
the spine, to which it is  attached by a broad part of the same  mem-
brane, and its anterior surface makes the posterior part of the cavity
behind the pericardium.
  Passing through the diaphragm it enters the  stomach, and is lined
with a very thick, soft,  and  white  cuticle, which is continued into
the first cavity of the stomach.
  The inner or true coat is white, of a considerable  density, and
not muscular, but thrown into large  longitudinal folds by the con-
traction of the  muscular fibres of the oesophagus, which  are very
strong.   It is very glandular; for on  its inner  surface, especially
near the fauces, orifices of a vast number of glands are visible.
  The oesophagus is larger in  proportion to the bulk of the animal
than in the quadruped, although  not so much  so as it  usually is in
fish, which we may  suppose swallow their food much in the same
way.  In the piked whale it was three inches  and a half wide.

  * [The supplementary note appended, in the second edition of the 'Lecons
d'Anatomie Comparee,  torn, ui., p. 376, to the imperfect description given bv
Cuvier of the formation of the whalebone, is a mere condensation of the minute,
original, and accurate account in the text: to which, however, no reference is
made by M. Duvernoy.] 
           OBSERVATIONS ON THE STRUCTURE, ETC.       359

  The stomach, as in other animals, lies on the left side of the body,
and terminates in the pylorus towards the right.
  In the piked whale the duodenum passes down on the right side,
very much as in the human subject, excepting that it is more ex-
posed, from the colon not crossing it.  It lies on the right kidney,
and then passes to the  left side  behind  the ascending part of the
colon and root of the mesentery, comes out  on  the  left "side, and
getting on  the edge of the  mesentery becomes  a loose intestine,
forming the jejunum.   In this course behind the mesentery it is ex-
posed, as in most  quadrupeds, not being covered by it  as in  the
human.  The jejunum and ileum pass along the edge of the mesen-
tery downwards  to the lower  part of  the abdomen.   The ileum
near the lower end makes a turn towards the right side, and then
mounting upwards, round  the edge of the mesentery, passes a little
way on the right, as high as the kidney, and  there enters the colon
or coscum.  The  caecum lies on the lower  end of the kidney, con-
siderably higher than in the human body, which renders the ascend-
ing part of the colon  short. The caecum is about seven inches
long, and more like that of the lion or seal than of any other animal
I know.
  The colon  passes obliquely up the right side, a little towards the
middle of the abdomen, and when as high  as the stomach crosses
to the  left and acquires a broad  mesocolon; at this part it lies upon
the left kidney,  and in  its passage down gets  more and more to the
middle line of the body.   When it  has  reached the  lower part of
the abdomen  it passes  behind the uterus and along with  the vagina
in the female, between the two testicles and behind the bladder and
root of the penis in the male, bending down to open on what is
called the belly of the animal, and  in its whole course it is gently
convoluted.  In those  which have no  caecum, and  therefore can
hardly be said to  have a colon, the intestine  before its termination
in the rectum makes the same kind of sweep round the other intes-
tines as the colon does where there is a caecum.
  The intestines are not large for the size of the animal, not being
larger in  those  of eighteen or twenty-four  feet long than in the
horse, the  colon  not much  more capacious  than the jejunum  and
ileum, and very  short; a circumstance  common to carnivorous
animals.  In  the piked whale the length from  the stomach to the
caecum is twenty-eight yards and  a half,  length of  caecum seven
inches, of the colon to the anus two yards and three-quarters.  The
small intestines are just five times the length of the animal, the colon
with the caecum a little more than one-half the length.
  Those parts that respect the nourishment of this tribe do not all so
exactly correspond as in land animals,  for in these  one  in some
decree leads  to the other.   Thus the teeth in the ruminating tribe
point out the kind of stomach, caecum,  and colon; while in others,
as the horse, hare, lion, &c, the appearances of the teeth only give
us the kind of colon and caecum ; but in this tribe, whether teeth or
no teeth, the stomachs do not vary much, nor  does the circumstance 
360           HUNTER ON THE  ANIMAL CECONOMY.
of cascum seem to depend on either teeth or stomach.   The circum-
stances by which from the form of  one part we judge what  others
are, fail us here:  but this may arise from not knowing all the cir-
cumstances.   The stomach in all that I have examined consists of
several bags continued from the first on the left  towards the right,
where the last terminates in  duodenum.   The  number is not  the
same in all:  for in the porpoise, grampus, and  piked whale there
are five; in  the  bottle-nose  (Hyperoodon) seven.  Their size res-
pecting one another differs very considerably, so  that the largest
in one species may in  another be only the  second.  The  two first
in the porpoise, bottle-nose, and piked whale are by much the largest;
the others are smaller, although irregularly so.
   The first stomach has, I  believe, in all  very much the shape of
an egg, with the small  end  downwards.  It is lined everywhere
with a continuation of the cuticle from the oesophagus.   In the por-
poise the oesophagus enters the superior end of the  stomach.   In the
piked whale  its entrance is a little way on the posterior part of the
upper end, and is  oblique.
   The second stomach in the piked whale is very large, and  rather
longer than the first.   It is of the shape of the italic <S, passing out
from the upper end of the first on its right side, by nearly as large
a beginning as the body of the bag.   In the porpoise it by no means
bears the same proportion to the first, and opens by a narrower
orifice; then passing down along the right side of the first stomach,
it bends a little outwards at  the  lower end, and terminates in the
third.   Where this second stomach  begins, the cuticle of the first
ends.*  The whole of the inside of this stomach is thrown into un-
equal rugas, appearing like  a large  irregular honeycomb.  In the
piked whale  the rugas are  longitudinal, and in many places very
deep, some of them being united by cross bands ; and in the por-
poise the folds are very thick, massy, and indented into one another.t
This stomach opens into the  third  by a  round contracted orifice,
which does not seem to be valvular.
   The third stomach is by  much the smallest, and  appears to be
only a passage between the second  and fourth.  It has no peculiar

  * [The lining membrane of the first stomach in the porpesse sends off a number
of irregular projections, where it surrounds the opening into the second stomach,
whereby that opening is rendered valvular, and adapted to prevent the passage of
anything but fluids or substances of very small size.  The first  stomach, there-
fore, serves not only as a reservoir, but the food undergoes a considerable change
in it, probably by the action of the gastric secretion of the second cavity regurgi-
tated into it.  Thus the bones offish have been found in  the first cavity  with all
the flesh dissolved, and the bones themselves softened by the removal  of their
earthy constituent.  See Preparation No. 569 c. Physiological Series, Hunterian
Museum.]
   f [It is to this stomach that the pneumogastric  nerves are principally distri-
buted ; the thick and soft  lining substance presents, according to the microsco-
pical researches of Sir David Brewster, a peculiar structure, consisting of closely
aggregated minute  tubes  placed  perpendicularly between the smooth  internal
mucous membrane and the vascular tunic which immediately lines the muscular
eoat.] 
           OBSERVATIONS ON THE STRUCTURE, ETC.        361

structure on the inside, but terminates in the fourth by nearly as
large an opening as its beginning.  In  the porpoise it is not above
one, and in the bottle-nose about five, inches long.
  The fourth stomach is of a considerable size; but a good deal less
than either the first or second.  In the piked whale it is not round,
but seems flattened between  the  second and fifth.  In the porpoise
it is long, passing in a serpentine course almost  like an intestine.
The internal surface is regular,  but  villous, and opens on its right
side into the fifth by a round opening  smaller  than the entrance
from  the third.
  The fifth stomach is in the piked whale round, and in the por-
poise oval ;*  it  is small,  and terminates  in the pylorus, which has
little of a valvular  appearance.  Its  coats  are thinner than those
of the  fourth, having an  even inner  surface, which  is  commonly
tinged with bile.
  The piked whale, and, I believe, the large whalebone whale, have
a caecum ; but it is wanting in the porpoise, grampus, and bottle-
nose whale.f
  The structure of the inner surface  of the  intestine  is  in some
very singular, and different from that of the others.
  The inner surface of the duodenum in the piked whale is thrown
into longitudinal rugas, or  valves, which are at some distance from
each other, and these  receive lateral folds.   The duodenum in the
bottle-nose swells out  into a  large  cavity, and  might almost be
reckoned an  eighth stomach ; but as  the gall-ducts enter it I shall
call it duodenum.
  The inner  coat of  the jejunum, and  ileum, appears  in irregular
folds, which  may vary according as  the muscular coat of the in-
testine acts : yet I  do not  believe that their form  depends  entirely
on  that circumstance, as  they run longitudinally, and  take a ser-
pentine course when the gut is  shortened by the contraction of the
longitudinal muscular fibres.   The  intestinal canal of the porpoise
has several  longitudinal folds of the inner  coat  passing  along it
through the whole of its length.   In  the bottle-nose the inner coat,
through nearly the whole track of the intestine, is Ihrown into large
cells, and these again subdivided into smaller; the axis of which
cells is not perpendicular  to a transverse  section of the intestine,
but oblique, forming pouches with the mouths downwards, and act-
ing almost like valves  when  anything is attempted to be passed in
a contrary direction ;  they  begin faintly in the duodenum, before
it makes its quick turn, and  terminate  near the anus.J   The colon

  * [This part we regard as the dilated duodenum, since the gall-ducts terminate
in it, and consequently reckon but four  compartments in the stomach of the por-
pesse.]
  f  [In all the  vegetable feeding Cetacea there is a caecum, but it is small.  In
the  dugong it  is of a simple conical form, and Very muscular.  In the manatee
the  caecum is bifurcate.]
  X [See the Preparations, Nos. 709, 710, 711, 712, Physiological Series, Hun-
terian Museum.]
                                32 
362
HUNTER ON THE ANIMAL CECONOMY.
and rectum have the rugas very flat, which seems to depend entirely
on the contraction of the gut.
   The  rectum in the piked whale near the anus, appears for four
or five inches much contracted, is glandular, covered by a soft cuticle,
and the anus small.
   I never found any air in the intestines of the tribe;  nor indeed in
any of  the aquatic animals.
   The  mesenteric artery anastomoses by large branches.
   There is a considerable degree of  uniformity in the liver of this
tribe of animals.  In shape it nearly resembles the human,  but is
not so thick at the base, nor  so sharp at the lower edge, and is pro-
bably not so firm in its texture.   The right lobe is the largest and
thickest, its falciform ligament broad, and there is a large  fissure
between the two lobes, in which  the round  ligament passes.   The
liver  towards the left is very much  attached to the stomach,  the
little  epiploon being  a thick substance.   There is no  gall-blndder.
The hepatic duct is  large,  and enters the duodenum about  seven
inches beyond the pylorus.*
   The  pancreas is a very  long, flat body, having  its left end  at-
tached  to the right side of the first cavity of the stomach : it passes
across the spine at the root of the mesentery, and near to the pylorus
joins the hollow curve of the duodenum, along which it is continued,
and adheres to that intestine, its duct entering that of the liver near
the termination in the gut.
   Although this tribe cannot be said to ruminate, yet in the number
of stomachs they come nearest to that order ;  but here I suspect that
the order of digestion is in some degree inverted.   In both the  ru-
minants, and  this tribe, I think it must be allowed  that the first
stomach is a reservoir.   In  the  ruminants the precise use of  the
second  and third stomachs is perhaps not  known; but digestion is
certainly  carried on  in the  fourth; while in this tribe, I imagine,
digestion is performed in the second,!  and the use of the third and
fourth is not exactly  ascertained.
   The caecum and colon do  not assist in pointing out the nature of
the food and mode of digestion in this tribe.  The porpoise, which
has teeth and four cavities to the stomach, has no caecum, similar to
some land animals, as the bear, badger, racoon,  ferret, polecat, &c.;
neither  has the bottle-nose a caecum which has only  two small teeth
in the lower jaw;  and the piked whale, which  has no teeth, has a

  * [In the dugong there is a gall-bladder of the usual dimensions, which is
chiefly peculiar for the mode in which the bile is conveyed to it; in other mam-
malia this takes place by a communication between the hepatic and cystic ducts,
at some distance from the bladder, but here two large hepatic ducts open directly
into the neck of the gall-bladder, in the same way as the ureters terminate in the
urinary bladder.  The cystic duct, which fulfils the office of the ductus communis,
proceeds to the duodenum, and becomes slightly dilated, before it enters that intes-
tine.  The manatee has  also a gall-bladder, but  it is wanting in the northern
manatee  or Rytina.]
  f [It is doubtless performed in  a great part by the secretion of the second, but
as before observed, the act is far advanced in the first cavity.] 
           OBSERVATIONS ON THE STRUCTURE, ETC.       363

caecum, almost exactly like the lion, which  has teeth and a very
different kind of stomach.
  The food of the whole of this tribe, I believe, is fish; probably
each may have a particular kind of which it is fondest, yet does not
refuse  a variety.  In the stomach  of the large bottle-nose I found
the beaks of some hundreds of cuttle-fish.  In the grampus I found
the tail of a porpoise;  so that they eat  their own genus.  In the
stomach of the piked whale I  found the bones of different fish, but
particularly those of the dog-fish.*   From the size of the oesophagus
we may conclude that they do not swallow fish so large in propor-
tion to their size as many fish do that we have reason  to be-
lieve take their food in the same way;  for  fish often attempt to
swallow what is larger than their stomachs can at one time contain,
and part remains in  the oesophagus till the rest is digested.
  The  epiploon on  the whole is a thin membrane;  on the  right
side it is rather a thin network,f though on the  left it is a complete
membrane, and near to the stomach of the same side becomes of a
considerable thickness, especially between the two first bags of the
stomach.  It has little or no  fat, except what  slightly covers the
vessels  in particular parts. It is attached forwards, all along to
the lower part of the different bags constituting the stomach, and
on  the right to the root  of the  mesentery between the stomach and
transverse arch of the colon, first behind to the transverse arch of
the colon and root of the mesentery, then to the posterior surface
of the  left or first bag of the stomach, behind the anterior attach-
ment.   In some of this tribe there is the  usual passage behind the
vessels going to the liver, common to all quadrupeds I am acquaint-
ed  with ; but in others, as the small bottle-nose, there is no  such
passage, by  which the cavity  behind the stomach in the  epiploon
of this animal becomes a circumscribed cavity.
  The spleen, in the piked  whale, is involved in the epiploon, and is
very small for the size of the animal.   There are in some, as the
porpoise, one or two small ones, about the size of a  nutmeg, often
smaller, placed in the epiploon behind the other.J  These are some-
times met with likewise in  the human body.
  The kidneys in the whole of this  tribe of animals are conglome-
rated, being made up of smaller parts, which are only connected by
cellular membrane, blood-vessels, and ducts, orinfundibula ; but not
partially connected by continuity of substance, as in the human body,
the ox, &c.:  every portion is  of a conical figure, whose apex is
placed towards the centre of the kidney, the base making the ex-
ternal surface;  and each  is composed  of  a cortical and  tubular
substance, the tubular terminating in the apex, which apex makes

  * [In the stomach of  the porpesse I have found the bones of an eel, and of a
flounder; these were in the first cavity.  The great sperm whale is nourished
principally by molluscaof the class of Cephalopods,  and their beaks seem to form
the nuclei of the intestinal concretions, called • ambergris.']
  f [It presents this reticulate structure in the otter.]
  X [The smaller accessory spleens  are sometimes four, five, or six in number.] 
3G4          HUNTER ON THE ANIMAL CECONOMY.
the mamilla.  Each mamilla has an infundibulum, which is  long,
and at its beginning wide, embracing the base of  the mamilla, and
becoming smaller.  These infundibula unite at last, and form the
ureter.   The whole kidney is  an oblong, flat  body, broader and
thicker at the upper end than the lower, and has the appearance of
being made  up of different parts placed close together,  almost like
the pavement of a street.
  The ureter comes out at the lower end, and passes along to the
bladder,  which it  enters very near the urethra.
  The bladder is oblong, and small for the size of  the animal.
In the female the  urethra  passes  along  to the  external sulcus or
vulva, and  opens just  under the clitoris, much as in  the human
subject.
  Whether  being inhabitants of the water makes  such  a construc-
tion of kidney necessary I cannot say; yet one must suppose it to
have  some connection with such  situation, since we  find  it almost
uniformly take place in animals inhabiting the water, whether wholly,
as this tribe, or occasionally, as the manatee, seal, and  white bear:
there is,  however, the same  structure in  the black  bear, which  I
believe never inhabits  the water.*  This, perhaps, should  be con-
sidered in another light, as Nature keeping up to a certain unifor-
mity in the structure of similar animals;  for the black  bear in con-
struction of parts is, in every other respect as well as this, like the
white bear.
  The capsulas renales  are small for the size of the animal, when
compared to the human, as indeed they are in most animals.  They
are flat, and of an oval figure;  the right  lies on the lower  and pos-
terior part of the  diaphragm, somewhat higher than the kidney; the
left is situated lower down, by the side of the aorta, between it and
the left kidney.  They are composed of two substances,  the external
having the direction of its fibres or parts towards the  centre; the
internal seeming  more  uniform, and not having so much of the
fibrous appearance.
  The blood of animals of this order is, I believe, similar to that  of
quadrupeds, but I have an idea that the red globules are in  larger
proportion.  I  will  not  pretend  to  determine  how far this may
assist in  keeping up the animal heat, but  as these  animals may be
said to live in a very cold climate or  atmosphere, and such  as
readily carries off heat from the body, they may want  some help of
this kind.
   It is certain that the quantity of blood in  this tribe and  in the
seal is comparatively  larger than in the quadruped, and  there-
fore  probably amounts  to  more than  that  of any other known
animal.

  * [In the beaver and other Rodentia of amphibious habits, the kidney presents
a simple undivided form ; and although in the  manatee and rytina the kidney
presents the subdivided type of formation, yet it has a smooth, unbroken external
surface in the dugong, and the papillae form two lateral series opening into a
single elongated pelvis.] 
              OBSERVATIONS OF THE STRUCTURE, ETC.        365

    This tribe differs from fish  in having the red blood carried to the
 extreme parts of the body, similar to the quadruped.
    The cavity of the thorax is composed of nearly  the same  parts
 as in the quadruped, but there appears to be  some  difference, and
 the  varieties in the  different genera  are greater.   The general
 cavity is  divided into two, as in the quadruped, by the heart and
 mediastinum.
    The heart in  this tribe and  in the seal is probably larger  in pro-
 portion to their  size than in the quadruped, as  also the blood-vessels,
 more especially the veins.
    The heart is inclosed in its pericardium, which is attached by a
 broad surface to the diaphragm, as in the human body.   It is com-
 posed of four cavities,* two auricles, and two  ventricles : it is more
 flat than in the quadruped, and adapted  to the  shape of the  chest.
 The auricles have more fasciculi, and these pass  more across  the
 cavity from side to  side than in many other animals; besides,  being
 very muscular they are very  elastic, for being stretched they con-
 tract again  very considerably.   There is nothing  uncommon  or
 particular in the structure  of the  ventricles, in the valves of  the
 ventricles, or in that of the arteries.
    The general  structure of  the arteries  resembles that of  other
 animals, and where parts are nearly similar the distribution is like-
 wise  similar.  The aorta forms  its usual curve,  and sends off the
 carotid and  subclavian arteries.f


   * As the circulation is a permanent part of the constitution respecting the class
 to which the animal belongs, and as the kind of heart corresponds with the cir-
 culation, these should be considered in the classing of animals.  Thus we have
 animals whose hearts have only one cavity, others with two, three, and four
 cavities.
   f [Both the  aorta and pulmonary artery are considerably dilated above their
 origin in the narwhale, according to Albers, Mayer, and Rapp (Cetaceen, p. 158,)
 In the porpoise the  aorta sends off, as usual, first the two coronary arteries, then
 three branches from the convexity of the arch.  The first of these is the largest;
 it sends off the posterior thoracic and then the right carotid, and lastly, divides into
 therightsubclavianand internal mammary arteries. The second branch sends offthe
 left carotid, subclavian, and internal mammary arteries ; but the  left posterior tho-
 racic arises, as a third branch, immediately from the arch of the aorta.  Notwith-
 standing the shortness of the neck, the common carotid, on each side, sends off a
 branch,  as in most mammalia, before  dividing into the external and  internal
 carotids; and the subordinate branches of both  these vessels  form plexuses in
 various parts of thehead, especially at the basis cranii,and around the optic nerve.
  The abdominal aorta lies deep in the cleft between the  right and left psoae
 muscles.  It gives off the caeliac, and close to it the superior  mesenteric, then, at
 a greater distance, a small  inferior mesenteric artery; also a right and left renal
 artery,  which,  in the  true Cetacea, enter the  upper or anterior extremity  of
 the kidney, and subdivides to distribute branches to the different lobules, like the
 stalk of a bunch of grapes.  The spermatic arteries are quickly resolved into
 plexuses.  The lumbar arteries are given off as usual in pairs ; and a little ante-
rior to the pelvic bones the aorta divides into two hypogastric arteries (which
 send off the umbilical arteries to the sides of the bladder), and a middle caudal
 artery, which is the largest, and passes, as a continuation  of the aortic trunk,
through the arches of the inferior spines.  There are no branches analogous  to
 common iliac and crural arteries.]
                                 32* 
366          HUNTER ON THE ANIMAL CECONOMY.

   Animals of this tribe, as has been observed, have  a greater pro-
portion of blood than any other known, and  there are many arte-
ries apparently  intended as  reservoirs, where a larger quantity of
arterial  blood  seemed  to  be required  in a part, and vascularity
could  not  be the  only object.   Thus we find  that  the intercostal
arteries divide into a vast  number of branches, which run in a ser-
pentine course  between the pleura and the ribs, and  their muscles,
making a  thick substance  somewhat similar to that  formed by the
spermatic artery in the bull.  Those vessels everywhere lining the
sides of the thorax pass  in between  the ribs near their articulation,
and also behind  the ligamentous attachment of the ribs, and  anas-
tomose with each  other.   The  medulla  spinalis is surrounded with
a network of arteries in the same manner, more especially where
it comes out from  the brain, where a thick substance is formed by
their ramifications and  convolutions ;  and  these vessels most pro-
bably anastomose  with those of the thorax."*
  The subclavian  artery in the piked  whale, before it passes over
the first rib, sends  down into the chest arteries which assist in  form-
ing the plexus on the inside of  the ribs;f  I am not  certain but the
internal mammary arteries  contribute  to  form the anterior part of
this plexus.  The  motion  of the  blood  in such must be very  slow,
the use of which we  do  not readily see.
   The descending aorta sends  off'  the intercostals, which are very
large, and give branches to  this  plexus;  and when  it has reached
the  abdomen,  it  sends  off, as  in  the quadruped, the different


  * [Tyson, who was  the first discoverer and describer of this structure (Anatomy
of a Porpesse, p. 32, pi. 2, fig. 7, 4to., 1680), speaks of it as a ' glandulous body,'
but describes it as a curious  contexture of blood-vessels variously contorted and
winding, emerging from the.medulla  spinalis at the holes where the nerves come
out between the ribs ; and he observes, " the same substance likewise for  a good
thickness covered  the medulla spinalis  throughout."  Hunter first determined
the exact nature of this structure, and that it  was a reservoir of arterial blood.
It is from this reservoir that the central  axis of the nervous system receives its
appropriate stimulus,  and the powerful muscles of the tail their supply of oxy-
genated blood during  the period of submersion and consequent interruption of the
respiratory function.   M. Breschet,  in a treatise ex professo on  this structure,
gives some beautiful figures of it.  (See Histoire Anatomique et Physiologique d*un
Organe de. Nature vasculaire decouvert dans les  Cetaces, par G. M. Breschet; 4lo.
1836).  He detected  it in the Delphinus  Delphis and Delphinus  Globiceps, and in'-
a fcetus of the Balxna Mysticelus ,•  but  in reasoning on the physiology of the
great arterial reservoirs which thus seem  to be common to the true Cetacea, it is
necessary to bear in  mind that the  structure does not exist in the herbivorous
Cetacea.]
  f [It also  gives off external thoracics to the pectoral muscles, a subscapular
branch, and one to the supraspinal fossa : these arteries supply the moving powers
of the fin: the trunk  then divides in two branches, which almost immediately
subdivide, and  lorm  plexuses upon  the humerus, which are expended in nour-
ishing the bones and  their ligaments  and  the enveloping integument.  This dis-
position is  but remotely analogous to the condition of the axillary artery in the
slow lemurs and sloth, where a plexus is formed by a sudden subdivision of the
trunk into numerous small branches,  which after a brief course reunite into the
common trunk, which then proceeds,  as brachial artery, to supply the muscles of
the forearm and hand.] 
OBSERVATIONS ON THE STRUCTURE, ETC.        367
branches to the viscera  and  the  lumbar arteries, which are  like-
wise very large for the supply of that vast mass of muscles which
moves the tail.
   In our examination of particular parts, the size of which is gener-
ally regulated  by that of  the whole animal, if we have  only  been
accustomed to see  them  in those  which are small or middle-sized,
we behold them with  astonishment in animals so far exceeding the
common bulk  as the whale.  Thus the  heart  and aorta of the
spermaceti whale appeared prodigious, being too large to  be  con-
tained  in  a wide tub, the aorta  measuring  a foot in  diameter.
When we consider these as  applied to the circulation, and figure
to ourselves that  probably ten or fifteen gallons of blood are thrown
out at one stroke, and moved with an immense velocity through a
tube of a foot diameter, the whole idea fills the mind with wonder.
   The  veins, I believe, have  nothing particular in their  structure,
excepting in parts requiring a peculiarity, as in the folds of the
skin on  the breast in  the piked whale, where their elasticity was to
be increased.*

                          Of the Larynx.

   The larynx in  most animals living on land  is a compound organ,
adapted  both  for respiration, deglutition, and sound, which last is
produced in the actions of  respiration; but in this tribe the larynx
I suppose is only adapted to respiration, as we do not know that
they have any mode  of producing sound.t
   It is  composed of os hyoides, thyroid, cricoid, and two  arytenoid
cartilages, with  the  epiglottis.  It varies very much  in  structure
and size, when compared  in animals of different genera.   These
cartilages were much smaller in the bottle-nose of twenty-four feet

   * [Hunter has previously  noticed the great capacity of the veins ;  they  are
also remarkable for their number and the immense plexuses which they form
in different parts of the body, but aboveall for the almost total absence of valves.
Tyson has given a figure of the extensive venous plexus situated on the  mem-
brane investing the psoas muscles (ibid., pi. 1, fig.  2, H.), and  these have
recently occupied the  attention  of Breschet, he. cit.,  and V. Baer (Acta  Acad.
Nat. Cur., vol. xvii., p. 1,1834).  The inferior and superior venae cavae are  not
brought into  communication  by  the vena azygos, as in other  mammalia; such
teins in  the usual situation in the chest would have been subject to compression
between the arterial  plexuses and the  lungs.  The venae azygos are therefore
represented by two venous trunks situated in the interior of the vertebral canal,
where they receive  the intercostal and  lumbar veins, and finally communicate
with the superior cava by means of a short single large trunk, which penetrates
the parietes of the  posterior and right side of the  chest.  The non-valvular
structure of the  veins in the Cetacea, and the pressure of the sea-water at  the
depths to which they retreat, when harpooned, explain the  profuse  and deadly
hemorrhage which follows a wound that in other mammalia would be  by no
means fatal.]
   f [My learned friend and colleague in the present work, Mr. T. Bell, considers
the evidence to be  strong, if not  incontestable, in favour of the existence of a
voice in the Cetacea.  It is variously decribed as a bellow, a grunt, or a melan-
choly cry ; of which he cites several instances in his beautiful work on British
quadrupeds, pp. 460, 475.] 
368          HUNTER ON THE ANIMAL CECONOMY.
 long than in the piked  whale seventeen feet, while the os hyoides
 was much larger.
    In the bottle-nose the  os  hyoides is  composed of three bones,
 besides two whose ends are attached to it, being  placed  above the
 os hyoides, making five in all.  In the  porpoise, piked whale, &c,
 it is but one bone, slightly bent, having a broad thin process passing
 up, which is a little forked: it has  no  attachment to the head by
 means of other bones, as in many quadrupeds.
   The thyroid cartilage in the  piked whale is broad from side to
 side, but not from the upper to the lower part:  it  has two lateral
 processes,  which  are  long,  and pass  down the  outside of the
 cricoid, near to its lower end, and  are  joined to  it  much as in the
 human subject.  These  differ in shape  in  different animals of this
 tribe.
   The cricoid cartilage is broad and flat, making the posterior and
 lateral part of the larynx, and is much deeper behind, and laterally,
 than before.  It is  extremely thick and strong, flattened on the pos-
 terior surface, and hollowed from the upper edge to the lower.  It
 terminates  by  a thick edge on the posterior part above, but irregu-
 larly at the lower edge, in the cartilages of the larynx.
   The two arytenoid  cartilages are  extremely projecting, and
 united  to each other till near their ends; are articulated on the
 upper edge of  the cricoid, but send down a process, which passes
 on the  inside of the cricoid,  being  attached to a bag in  the piked
 whale, which is formed below  the  thyroid  and before the cricoid
 cartilages ; they cross the cavity of the larynx obliquely, making the
 passage at the upper part a groove between them : the  cavity at
 this place swells out laterally, but is  very narrow between the  ante-
 rior and  posterior  surfaces.   The  passage above between the
 arytenoid and  thyroid  cartilages  is  wide  from side to side, and is
 continued  down on the outside of the  processes of the  arytenoid
 cartilage, as well  as  between  them, ending  below  the thyroid,
 which is folliculated on its inner surface  on the fore  part of the cri-
 coid cartilage.
   The epiglottis makes a third part of the passage,  and completes
 the glottis by forming  it into a canal, in several of this tribe; but
 in the piked whale  it was not attached  to the two arytenoid  car-
 tilages, but only in contact, or inclosing  them  at  their base,  so as
 to make them form a complete canal.
   I could not observe anything like a thyroid gland.*
   From the glottis  and epiglottis  being so connected as to make
 but one canal, and from the thyroid and cricoid cartilages being so
 flattened in some between the anterior  and posterior surface, the
 passage through these parts is very small or contracted; but the
 trachea swells out again into a very considerable  size.   Its larger
 branches  are in proportion to the trunk,  and enter the lungs at the
upper end along with the blood-vessels.

  * [This body certainly exists both in the porpoise and bottle-nose dolphin • it
is bilobed, and placed transversely across the trachea. Below this body is the
thymus, which extends into the chest and is much subdivided.] 
OBSERVATIONS ON THE STRUCTURE, ETC.       369
                        Of the Lungs.

  The lungs are two oblong bodies, one on each side of the chest,
and are not divided into smaller lobes, as  in  the  humam  subject.
They are of considerable length, but not so deep between the  fore
and back part as in the quadruped, from the heart being broad, flat,
and of itself filling  up the fore part of the chest.   They pass further
down on the  back  part than in the quadruped, by which their size
is increased, and rise higher up in the chest than the entrance of
the vessels, coming to a point at the upper end. From the entrance
of the vessels they  are  connected downwards, along their whole
inner edge, by a strong attachment (in  which there are in  some
lymphatic glands)  to  the posterior mediastinum.   The lungs are
extremely elastic in their substance, even so much so as to  squeeze
out any air that may be thrown into them, and  to  become almost
at once a solid mass, having a good deal the appearance, consistence,
and  feel of an ox's spleen. The  branches  of the bronchias which
ramify into the lungs have not the cartilages flat, but rather rounded;
a construction which admits of greater motion between each.*
  The pulmonary  cells are smaller than in quadrupeds, which may
make less air necessary, and they communicate  with each other,
which those of the quadruped do not; for  by  blowing into one
branch of the trachea,  not only the part to which it immediately
goes, but the whole lungs are filled.
  As the ribs in this tribe do not completely make  the cavity of
the thorax, the diaphragm has not the same  attachments as in the
quadruped, but is connected forwards to the abdominal muscles,
which are very strong, being a mixture of muscular and tendinous
fibres.
   The position of  the diaphragm is  less  transverse than in the
quadruped, passing more obliquely backwards, and  coming  very
low  on the spine, and higher up  before; which  makes  the  chest
longest in the direction of the animal at the back, and gives room
for the lungs to be continued along the spine.
   The  parts  immediately concerned in inspiration  are  extremely
strong;  the diaphragm remarkably so.  The reason of this  must
at once appear; it necessarily requiring great force to expand in a
dense medium  like water, especially too when the vacuity is  to be
filled with one which is rarer, and is to water a species of vacuum,
the pressure  being much greater on  the external surface than the
counter-pressure from  within.  But expiration on  the other  hand
must be much more easily performed ; the natural elasticity of the
parts themselves, with the pressure of the  water on the  external
surface  of the body, being greater than  the resistance of the air

  * [The cartilaginous hoops of the bronchiae ar continued to their extreme rami-
fications.  The pleura costalis is denser and stronger in the porpoise than serous
membranes usually are.] 
370
HUNTER ON THE ANIMAL CECONOMY.
within, will both tend to produce expiration without any immediate
action of the muscles.*
   The diaphragm, in these animals, appears to  be  the  principal
agent in  inspiration ;  and the cavity of the thorax not being entirely
surrounded by bony parts, is of course  less easily expanded, and
the apparatus for its expansion in all directions, as in the quadruped,
does not exist here.

             The Blow-hole, or Passage for the Air.

   As the nose in every animal that breathes air is a common pas-
sage for  the air, and is also the organ of smelling, I  shall describe
it in this tribe as instrumental to both these  purposes.
   There is a variety in  some species of this  animal which is,  I
believe,  peculiar to this  order; that is, the want of the  sense of
smelling; none  of those which I have yet examined  having that
sense, except the two kinds of whalebone  whale : such of course
have neither the olfactory nerves, nor the organ ; therefore in them,
the nostrils are intended merely for respiration ; but others have the
organ placed in this passage as in other animals.
   The membranous portion of the posterior nostrils is one  canal;
but when in the bony part, in most of them, it is divided into two;
the spermaceti  whale, however, is an exception.   In those  which
have it divided, it is in some continued double through the anterior
soft parts, opening by two orifices, as in the piked  whale; but in
others, it unites  again in the membranous part, making externally
only one orifice, as in the porpoise, grampus, and bottle-nose.  At
its beginning in the  fauces, it is a roundish  hole, surrounded by a
strong sphincter muscle, for grasping the epiglottis;  beyond this,
the canal becomes larger, and opens into  the two passages in the
bones of the head.   This part is very glandular, being full of folli-
cles,  whose ducts  ramify in  the surrounding  substance,  which
appears  fatty and muscular like the  root of the tongue, and these
ramifications communicate with one another, and contain a viscid
slime.   In the spermaceti  whale, which has a single canal, it is
thrown a little to the left side.
   After  these  canals  emerge from the bones  near the  external
opening,  they become irregular, and have several sulci passing out
laterally, of irregular forms, with  corresponding eminences.  The
structure of these eminences is muscular and  fatty, but less mus-
cular than the tongue of a quadruped.
   In the  porpoise there are two sulci on each side;  two large and
two small, with corresponding eminences of  different shapes, the
large ones being thrown into folds.
   The spermaceti whale has the least of this  structure;  the ex-
ternal  opening  in it comes  further forwards towards the anterior

   * [Professor Mayer, of Bonn, has however recently described a muscular mem-
brane as immediately investing the lungs in the dolphin.] 
OBSERVATIONS ON THE STRUCTURE, ETC.       371
part of the head, and is consequently longer than in others of this
order.   Near to its opening externally, it forms a large sulcus, and
on  each side  of this canal is  a cartilage,  which runs nearly its
whole length.  In all  that I have  examined, this canal, forwards
from the bones, is entirely lined with a thick cuticle of a dark colour.
  In those which have only one external opening, it is transverse,
as in the porpoise, grampus, bottle-nose and spermaceti whale, &c.;
where double,  they  are  longitudinal, as in the piked whale, and
the large whalebone whale.  These openings form a passage for
the air in respiration to and from the lungs : for it would be impos-
sible for these animals to breathe air through the mouth; indeed, I
believe the human species alone breathe by the mouth, and in them
it is mostly from habit; for in quadrupeds the epiglottis conducts the
air into the nose.
   In the whole of this tribe, the situation  of the opening on  the
upper surface  of the head is well  adapted  for this purpose,  being
the first  part that comes  to the surface of the water in the natural
progressive motion of the animal ; therefore it is to be considered
principally as a respiratory organ, and where it contains the organ
of smell, that is only secondary.
   As the animals of this order do not live in the medium which
they inspire, the organs conducting the air to the lungs are in some
sort particularly constructed, that the water in which they live may
not interfere with the air they breathe.
   The projecting glottis, which has been described, passes into the
posterior nostrils, by which means it crosses the fauces, dividing
them into  two passages.  The  enlargement of the termination of
the glottis, observed in some of them, would seem to be intended to
prevent its retraction :  but, as it seems confined to the porpoise and
grampus, it may, perhaps, in them  answer  some other purpose.
   The beginning of the posterior nostrils, which answers to the pala-
tum molle in  the  quadruped,  having a  sphincter,  the glottis is
grasped  by it, which renders its situation still more secure, and the
passages through the head, across the fauces and along the trachea,
are  rendered  one continued canal; this union of glottis  and epi-
glottis with the posterior nostril, making only a kind of joint, admits
of motion, and  of dilatation and contraction  of the fauces, in deglu-
tition, from the epiglottis moving  more in or out of  the posterior
nostril.
   This  construction of parts answers a purpose  similar to that of
the epiglottis in the  quadruped; it  may  be considered  as the epi-
glottis and the arytenoid cartilages joining to make a tubular or
cylindrical epiglottis, instead of a valvular one.
   The reasons why there should  be so peculiar a construction of
parts do not at first appear; but we certainly see by it an absolute
guard placed upon the lungs, that no water should get into them.
   This  tribe being without the projecting tongue of the quadruped,
and wanting its extensive motion and the power of sucking things
into the mouth, may probably require the construction between the 
372
HUNTER ON THE ANIMAL CECONOMY.
air and lungs to be more perfect;  but how far it is so I will not pre-
tend to say.
                 The Brain and Medulla Spinalis.

   The  size  of the brain differs much  in different genera of this
tribe, and likewise in the proportion it bears to the bulk of the ani-
mal.   In the porpoise,  I believe, it  is the largest,  and perhaps in
that respect comes nearest to the  human.
   The  size of the cerebellum in proportion to that of the cerebrum
is smaller in the human  subject than  in any animal with which I am
acquainted.   In many quadrupeds, as the horse, cow,  &c, the  dis-
proportion in size  between cerebellum and cerebrum  is not great,
and in  this tribe it is still less ; yet not  so small as in the bird, &c.
   The whole brain in this tribe is compact, the anterior part of the
cerebrum  not projecting so far forwards as in either the quadruped
or in the human subject;  neither is the medulla oblongata so promi-
nent, but flat, lying in a kind  of hollow  made by the two lobes of
the cerebellum.*
   The brain is composed of cortical and medullary substances, very
distinctly marked  ; the cortical being in colour like the tubular sub-
 stance of a kidney, the medullary  very white.   These substances
 are nearly in the same  proportion as in the human brain.  The two
 lateral ventricles are large, and in those that have olfactory nerves
 are not continued  into them  as  in  many quadrupeds ; nor do they
 wind  so much  outwards  as  in the human subject, but  pass  close
 round  the  posterior ends of the  thalami nervorum opticorum.f
 The thalami themselves  are large, the corpora striata small ;J the
 crura of the fornix are continued  along the windings of the  ven-
 tricles, much as in the  human subject.^   The plexus choroides is at-
 tached to a strong membrane which covers the thalami  nervorum
 opticorum, and passes  through the whole course  of  the  ventricle,
 much  as in the human subject.||

   * [The most characteristic feature of  the brain of the Cetacean is its great
 breadth, which  exceeds its length.  Each hemisphere  is divided below by a
 fissura magna into an anterior and  middle lobe, which extends over the cerebel-
 lum, so as to form a posterior lobe.]
   t [They extend, as in the  human subject, into an anterior, descending, and
 posterior horn : but the latter is very small.]
   X [The smallness of size of these parts,  and the shortness of the anterior lobes
 of the brain are in relation with  the absence of olfactory nerves.  The corpora
 striata  are brought  into communication  with  each other  by an anterior com-
 missure.]
   § [The fornix sends down two slender anterior pillars to the corpora albicantia,
 and is continued into the  anterior  part of the corpus callosum ;  it then bends
 backwards along the under surface of the  corpus callosum and above the thalami,
 and its posterior crura sink down, and diverge from each other to form the hip-
 pocampi.]
    || [The hemispheres of the brain are  united by  a corpus callosum,  chiefly
 remarkable for its position, being  much inclined downwards and forwards; its
  size is large, bearing the usual proportion to that of the hemispheres. The bige-
  minal bodies are large ; the anterior pair are rounded and  lie close together •  the 
OBSERVATIONS ON THE STRUCTURE, ETC.        373
  The substance of the brain is more visibly fibrous than I ever saw
it in  any other  animal, the fibres passing from the  ventricles as
from a centre to the  circumference, which fibrous texture  is also
continued through the cortical substance.  The whole brain in the
piked whale weighed four pounds ten ounces.*
  The  nerves going out from the brain, I  believe, are  similar to
those of the quadruped, except in the want of  the olfactory nerves
in the genus of the porpoise.
  The medulla spinalis is much smaller in proportion to  the size of
the body than in the human species, but still bears some proportion
to the quantity of brain; for  in  the porpoise, where the brain is
largest, the medulla spinalis is largest; yet this did not hold good in
the spermaceti whale, the  size of the medulla  spinalis appearing to
be  proportionally larger than  the  brain, which was small when
compared to the size of the animal.   It has a  cortical part  in the
centre, and terminates about the twenty-fifth vertebra, beyond which
is the cauda equina, the dura mater going no  lower.  The nerves
which  go off  from the medulla spinalis are more  uniform  in size
than in the quadruped, there being no such inequality of parts, nor
 any  extremities to be supplied, except the fins.f
   The medulla spinalis  is  more fibrous in  its structure than in
other animals; and  when an attempt is made to break  it  longitu-
dinally it tears with a fibrous appearance, but transversely it breaks
irregularly.J
   The dura mater lines the skull, and forms in some the three pro-
cesses  answerable to the divisions  of the brain, as  in the human
subject;  but in others this is bone.   Where it covers the  medulla
 spinalis it differs  from  all  the  quadrupeds I am acquainted with,
 inclosing the medulla closely, and the nerves  immediately  passing
out through it at the lower part, as they do  at the  upper, so that
 the cauda equina, as it forms, is  on the outside of the dura mater.

 posterior are oval, and are separated by a depression which receives the anterior
 part of the vermiform process of the cerebellum.   The medulla oblongata is cha-
 racterized by the absence of the trapezoid bodies, in which respect it resembles
 that in the human subject and orang.   The remarkable number and depth of the
 cerebral convolutions have  been noticed by Tyson in  the porpoise, by  Scoresby
 in the whale, and by Tiedemann in the dolphin.]
  * [Scoresby found the brain of the mysticete whale (Balxna Mysticetus) to
 weigh three pounds twelve ounces.  Tyson  found the brain of  a porpoise, which
 weighed ninety-six pounds avoirdupoise, to weigh sixteen ounces and a half.  I
 found the weight of  the brain of an  adult male porpoise to  be one pound two
 ounces and three-quarters avoirdupoise.]
   f [The  anterior roots of the spinal nerves are the largest: the posterior roots,
 after piercing the dura mater, are continued for a third of an inch before the gan-
 glion is formed upon them, in  the dorsal region ; and the separate roots are pro-
 gressively longer as they come  off nearer  the caudal extremity of the spinal
 chord.  In the  porpoise,  from  which  the above decription is taken, I counted
 forty-one pairs of spinal nerves:  the cervical are closely approximated in conse
 quence of the shortness of the neck.]
   X [The canal continued from the fourth ventricle is persistent  in the anterior part
 of ihe spinal chord, as in the horse.]
                                 33 
374
HUNTER ON THE ANIMAL CECONOMY.
                     The Organs of Sense.

  As the organs of sense are variously formed in different animals,
fitted for the various modes of impression ; and as the modes are
either increased or varied, according to circumstances which make
no part of the sense itself, but which are necessary for the ceconomy
of the animal, we find the senses in this tribe  varied in their con-
struction, and in some a sense  is even wholly wanting.
  The organs of sense which appear to be adapted to every mode
of life are those of touch and taste; but those of  smell, sight, and
hearing, probably require to be varied according to circumstances.
Thus smell may be increased by a mode of impregnation, hearing
by the vibration of different mediums,  and sight  by the  different
powers  of refraction of  different  mediums; therefore  as animals
are intended by Nature to be differently circumstanced, so are the
senses formed.

                    Of the Sense of Touch.

  The cutis in this tribe appears in general particularly well calcu-
lated for sensation, the whole surface being covered  with villi,
which are so many vessels, and we must suppose nerves.   Whether
this structure is only necessary for acute sensation, or whether it is
necessary for common sensation, where  the  cuticle is thick and
consisting of  many layers, I do not know.  We may observe that
where it is necessary the sense of touch should be  accurate the villi
are usually thick and long, which  probably is necessary, because in
most parts of the body, where  the more acute sensations  of touch
are required, such  parts  are covered by a thick cuticle.   Of  this the
ends of our fingers, toes, and the foot  of the  hoofed animals, are
remarkable examples.
  Whether this sense is more  acute in water, I  am not certain ;
but should imagine it is.

                     Of the Sense of Taste.

  The tongue, which is  the organ of taste, is also endowed with
the sense of touch.  It is likewise to be considered, in the greatest
number of animals, as an instrument for mechanical purposes ;  but
probably less so in this  tribe  than any other.  However, even  in
these it must have  been formed with this view, since merely as an
organ of taste it would only have  required surface, yet  is  a  pro-
jecting body endowed with motion.  In some  it is better adapted
for motion than in  others ; and I should suppose this to be requisite,
on account of the difference in the mode of catching the  food and
in the  act of swallowing.  It is most projecting  in those with
teeth, probably for the better conducting  the food, step  by  step, to
the oesophagus;  whereas it does not seem so necessary to have such
management  of the tongue in those which  have  no  teeth, and 
OBSERVATIONS ON THE STRUCTURE, ETC.       375
catch their  food by  merely opening the  mouth and swimming
upon it, or by having their prey carried  in by the water.   In the
porpoise and grampus it  is firm in  texture, composed of muscle
and fat, being pointed and  serrated on  its edges, like that of the
hog.*
  In the spermaceti whale the tongue was almost like a  feather-
bed.!   In  the piked whale  it was but gently raised, hardly having
any lateral edges, and its tip projecting but  little, yet, like  every
other tongue, composed of muscle  and fat.  The  extent between
the two jaw-bones in  this whale was very considerable, taking in
the whole width of the head or upper jaw, and of course including
the whalebone.  This extent of surface between jaw and jaw, having
but little projection of tongue, is almost  flat from side to side, is
extremely elastic when contracted, and throws the inner membrane
into a  vast  number  of very small folds, that  run  parallel to  one
another, but which are again thrown into a close serpentine course
by the elasticity of the part  in  a  contrary direction.  From  the
tongue being capable  of but little motion, there is only a small mass
of muscle required;  and, from  the thinness of the jaw-bone, the
distance between the  lower surface of the mouth and  external  sur-
face of the skin is but small; and this skin being ribbed and very
elastic is capable of considerable distention, by which the cavity of
the mouth can be enlarged.
   The  tongue of the large  whalebone  whale, I should suppose,
rose in the mouth considerably ; the two jaws at the  middle being
kept at such a distance on account of the whalebone, so that the
space between, when  the  mouth is shut, must be filled  up by the
tongue.

                    Of the Sense of Smelling.
   In this tribe of animals  there is something  very remarkable in
what relates to the sense of smelling; nor have I been able to  dis-
cover the particular mode by which it is performed.
   When we consider these animals as  mammalia, and  only con-
structed differently in external form for  progressive motion through
water, we must see that it was necessary that all the senses should
correspond with this medium: we must therefore be  at a  loss to
conceive how they smell,  since  we may observe that the organ for
smelling water, as in  fish, is very different from that formed to smell
air; and as we must  suppose this  tribe are only to smell water,
being the  medium in which such odoriferous particles can  be dif-
fused, we should expect their organ to be similar to  that of fish;
but in that case nature would have been  obliged  to  have attacked
the nose of  a  fish to an animal constructed like a quadruped;  and

  * [We have found the marginal serration of the tongue of the hog only in the
fcetus or very young state.]
  f [It is, however, of much smaller size in this species than in the whalebone
whales.] 
376          HUNTER ON THE  ANIMAL CECONOMY.
it is contrary to the laws which are established in the animal crea-
tion to mix parts of different animals together.
  In many of this tribe there is no organ of smell at  all;  and in
those which have such an organ, it is not that of a fish, therefore
probably  not calculated to smell  water.   It  becomes  difficult
therefore to account for  the manner in which such  animals smell
the  water;  and  why the  others should not have had such  an
organ,* which, I believe, is peculiar to the large and small whale-
bone whales.
  Although  it is not the external  air which  they inspire that pro-
duces smell, I believe it is the air retained in the nostril out of the
current of respiration, which by being  impregnated with the odori-
ferous particles contained in the water  during the act of blowing, is
applied to the organ of smell.  It might be supposed that they could
smell the air on the surface  of the water  by every inspiration, as
animals do on land ; and probably they may: but this will not give
them the power to smell the  odoriferous particles  of their prey in
the water at any depth; and as their organ is  not fitted  to  be
affected by the application of water, and as they cannot suck water
into the nostril without the danger of its passing into the lungs, it
cannot be by its application  to this organ  that  they are  enabled
to smell.
  Some have the power of  throwing  the water  from  the mouth
through the  nostril, and with such force as  to raise it  thirty feet
high : this must answer some important purpose,  although  not  im-
mediately evident to us.
  As the organ appears to be. formed to  smell air only, and as I
conceive the smelling of the external  air could not be of use as a
sense, I therefore believe that they do not smell in inspiration ;  yet
let us consider how they  may be  supposed to smell the odoriferous
particles of the water.
  The organ of smell is out of the direct road of the current of air
in inspiration; it is also out of the current of water when they
spout;  may we not suppose then, that this sinus contains air, and as
the  water passes in the act of throwing it out, that it impregnates
this reservoir of air, which immediately affects the sense of smell 1
This operation is probably performed in the time of expiration, be-
cause it is said  that this water is sometimes very offensive; but all
this I only give as conjecture.
  If the above solution is just, then only those which have the organ
of smell can spout, a fact worthy of inquiry.
  The  organ  of smell would appear to be less necessary in these
animals than in those which live in air, since some are wholly de-
prived of it;  and the  organ in those which  have it is  extremely

  * Is the mode of smelling in fish similar to tasting in other animals ?  Or is the
air contained in the water  impregnated with the odoriferous parts, and this air the
fish  smells ?  If so, it is somewhat similar to the breathing of fish, it not being
the water which produces the effect there, but the air contained in it.  This I
proved by experiments, and is mentioned by Dr. Priestly. 
OBSERVATIONS ON THE STRUCTURE, ETC.        377
small, when compared with  that of other animals, as well as  the
nerve which is to receive the impression, as was observed above.*


                      Of the Sense of Hearing.

   The  ear is constructed much upon the same principle  as in  the
quadruped ; but as it differs in several respects, which it is necessary
to particularize, to convey a perfect idea of it the whole should be
described.  As this would exceed the limits of this  paper, I shall
content myself with a  general description, taking  notice of those
material points in which it differs from that of the quadruped.
   This organ consists of the  same parts as  in the quadruped ; an
external  opening, with a  membrana  tympani,  an Eustachian tube,
a tympanum with its processes, and the small bones.f   There is no
external projection  forming a funnel, but merely an external open-
ing.  We can easily assign a  reason why there should be no pro-
jecting ear, as it would interfere with progressive motion; but  the
reason why it is not formed as  in  birds, is not so evident;  whether
the percussions of water could  be collected into one point as air, I
cannot say.   The tympanum is constructed with irregularities, so
much like those of an external  ear, that I could suppose it to have
a similar effect.
   The external opening begins  by a smalt  hole, scarcely percepti-

  * [It is singular that Mr. Hunter should not have  added a description of the
organ, the function of which is the  subject of so  many singular and original
speculations in the preceding section.
  The olfactory nerve in the whalebone whale (Balaena Mysticetus) is solid, as
in the human subject, but round, about half an inch in diameter at its narrowest
pa'rt, and gradually swelling into a pyriform bulbous termination,  from the fundus
of which the divisions of the nerve pass off through the foramina of the cribriform
plate; the larger of these foramina are from one to  two lines in  diameter, about
twenty in number, and placed chiefly  around the circumference of the cribriform
plate ; there are two large ones in the centre which lead to the root of the middle
spongy bone.  The lamella itself is concave towards the fossa of the nerve.
  The nerves are lodged for some distance in a peculiar cavity, surrounded by
the cancellous diploe of the skull, leading from the oranial cavity to the cribriform
plate. The turbinated bones are three in number, but are none of them distinct,
merely projections from the side of the nasal cavity into its area.  The middle
one is the largest; besides its lateral adhesion, it is  attached by a narrow pedicle
to the cribriform plate, from which it  quickly expands into a body of about  one
and a half inch in diameter, having  an  upper, middle, and lower protuberance
separated by sinuosities; but the bone is not a  convoluted plate, but solid, or
having its substance of the same cellular structure as the surrounding diploe.
The inferior turbinated process  is a simple elliptic protuberance, about one inch
in length and half an inch in width.
  The olfactory nerves in the Balxnoptera are somewhat larger than in the human
subject; they are of a  pulpy texture, yet readily divisible  into fasciculi, and
terminate in a small bulb which rests  on the cribriform plate.  Treviranus states
that olfactory nerves, but of very minute size do, exist in the porpoise; and V.
Baer describes them  as being one-sixth of a line in diameter in the Delphinus
Delphis.]
  X [The internal ear or labyrinth, which Hunter afterwards describes as  ' the
immediate organ,' seems to have been accidentally omitted in the above enume-
ration.]
                                 33* 
378           HUNTER ON THE ANIMAL CECONOMY.
ble, situated on the side of head  a little  behind the eye.*  It is
much longer than in other animals, in consequence of the  size of
the head being  so much increased beyond the cavity that contains
the brain.   It  passes in  a  serpentine course, at first horizontally,
then downwards, and afterwards horizontally again, to  the mem-
brana  tympani, where  it terminates.    In  its whole length it is
composed  of different cartilages, which  are irregular  and  united
together  by cellular membrane,  so  as to  admit of motion  and
probably of lengthening  or shortening, as the animal is more  or  less
fat.
   The bony part of the organ is not so much inclosed in the bones
of the skull as in the quadruped, consisting commonly of a distinct
bone or bones,  closely attached  to  the skull, but in general readily
to be separated from it ;f yet in  some it sends off, from the posterior
part, processes which unite with the skull.  It varies in its  shape,
and is composed of the immediate organ and the tympanum.
   The immediate organ is, in point of situation to that of the tym-
panum, superior and internal, as in the quadruped,  The tympanum
is open at the  anterior end, where the Eustachian tube begins.
   The Eustachian tube opens on the outside of the upper  part of
the fauces: in  some higher in the  nose  than  others ;  highest I be-
lieve in the porpoise.  From  the cavity of  the tympanum  where
it is rather largest, it passes forwards  and  inwards, and near its
termination appears  very much  fasciculated, as if glandular.J
   The Eustachian tube and tympanum  communicate with  several
sinuses, which, passing in various  directions, surround the bone of
the ear.   Some of these are cellular, similar to the cells of the mas-
toid process in the human subject, although not  bony.  There is a
portion of this cellular structure of a particular  kind, being white,
ligamentous, and each part rather rounded than  having flat sides.§

   * [In the full-grown spermaceti whale Mr. F. D. Bennett found the  aperture
of the meatus auditorius to form a narrow longitudinal fissnre, one inch in length;
it admitted with difficulty the extremity of the index finger.]
   X [Being  united to  the skull by fibrous texture only, a structure which is
peculiar to the Cetacea, but not universal in that order.]
   X [The Eustachian tube in the true Cetacea is characterized by its membranous
 structure throughout; its parietes are  nowhere supported by cartilage, nordoes it
traverse any bone.  In  the porpesse  its  internal surface is provided with many
semilunar valves, the free margins of which are directed towards the nasal outlet
 of the tube.]
   § These communications with the Eustachian tube may be compared to a large
 bag on the bases of the skull of the  horse and ass, which is a lateral swell of
 the membranous  part of the  tube, and  when  distended  will contain  nearly  a
 quart.a
   a [In a beautiful drawing of the organ of hearing in the porpoise, recently
published by the College of Surgeons, Hunter gives a view of part of the sinuses
which communicate with the tympanum and Eustachian tube.  See Physiologi-
 cal Catalogue of the Hunterian Collection, vol. iii., pi. xxxiv. i. k.  In the pre-
 paration (No. 1582) the sinuses are seen  to  contain numerous  small worms
 (Strongylus minor), Kuhn, Mem. du Museum, torn, xviii., p. 363. The same have
 been observed by other physiologists, as Klein, Camper, Albers, and Rudolphi,
 the latter of whom regards them as a small variety of the Strongylus inflexus.] 
OBSERVATIONS ON  THE STRUCTURE, ETC.       379
One of the sinuses passing out of the  tympanum close to the mem-
brana tympani, goes a  little  way in  the same direction, and com-
municates with a number of cells.
  The whole function of the Eustachian tube is perhaps not known ;
but it is evidently a duct from the cavity of the ear, or a passage
for the mucus of these  parts; the external  opening  having a par-
ticular form would  incline us to believe, that something was con-
veyed to the tympanum.
  The bony part of the organ is very hard and brittle, rendering it even
difficult to be cut with a saw without itschipping into pieces.  That part
which contains the  immediate  organ is by much the hardest, and
has a very small portion of animal substance in it; for when steep-
ed in an acid, what remains is  very soft, almost like a jelly, and
laminated.  The bone is not only harder in  its substance  but there
is on the whole more solid bone  than in the corresponding parts
of quadrupeds, it being thick and massy.
   The part  containing the tympanum  is a thin bone, coiled upon
itself, attached by one end to the portion which  contains the organ;
and  this attachment in some is by close contact only, as in the nar-
whale ; in others, the bones  run into one another, as in the bottle-
nose  and piked whales.
   The concave side of the tympanum is turned towards the organ,
its two edges being close to it; the outer is irregular, and in many
only in contact, as in the porpoise: while in others the union is by
bony continuity, as in the bottle-nose whale, leaving a passage on
which the  membrana  tympani is stretched, and  another opening,
which is the  communication with the sinuses.
   The surface of the bone containing the immediate organ opposite
to the mouth of the tympanum is very irregular, having a number
of eminences and cavities.  The cavity of the tympanum is lined
with a  membrane, which also  covers  the  small  bones with their
muscles, and appears to have a thin  cuticle.  This membrane ren-
ders the bones, muscles, tendons, &c, very obscure, which are seen
distinctly when that is removed. It appears to be a continuation
of the periosteum,  and the only uniting substance between the small
bones.   Besides the general  lining,  there  is a plexus of vessels,
which is thin and rather broad, and attached by one edge, the rest
being loose in the cavity of the tympanum, somewhat like the plexus
 choroides in  the ventricles of  the brain.  The  cavity we may sup-
pose intended to increase sound, probably  by  the vibration of the
bone; and from its particular formation  we can easily conceive,
that the vibrations  are  conducted, or reflected, towards the imme-
diate organ,  it being in some degree a substitute for the external

   The external opening being  smaller than in any animals of the
 same size, the membrana tympani is  nearly in the same proportion.
 In the bottle-nose whale, the grampus, and porpoise, it is smooth and
 concave externally, but of a particular construction  on the inner
 surface ; for a tendinous process passes from it towards the malleus, 
380           HUNTER ON THE ANIMAL CECONOMY.
converging as it proceeds from the membrane, and becoming thin-
ner till its insertion into  that bone.   I could not discover whether
it had any muscular  fibres  which could  affect  the  action of the
malleus. " In the piked whale, the termination of the external opening,
instead  of being smooth  and concave, is  projecting, and  returns
back into the meatus for above an inch in length,* is firm in  texture,
with thick coats, is hollow  on  its  inside, and its mouth communi-
cating with the tympanum; one  side being  fixed to the malleus,
similar  to  the  tendinous process  which  goes from the inside of the
membrana tympani in the others.f
  A little way within the  membrana tympani, are placed the small
bones, which  are three in  number,  as  in the quadruped, malleus,
incus, and stapes ; but in the bottle-nose whale there  is  a  fourth,
placed on the  tendon of the  stapedius muscle.  These bones  are as
it were suspended between  the bone of  the tympanum and that of
the immediate organ.
  The  malleus  has  two attachments, besides that with the incus;
one close  to the bone of the tympanum, which, in the porpoise, is
only by contact, but in others by a bony union ;J the  other attach-
ment is formed by the tendon, above described, being united to the
inner surface of the  membrana tympani.  Its base articulates with
the incus.

  *  [As might be expected, the same structure exists in  the whalebone whale
(Balxna Mysticetus, Linn.), where, according to Home, the membrana tympani
" instead of being concave, as in other animals,  towards the meatus externus, is
convex and projects nearly an inch into that tube." Phil. Trans. 1812, p. 84. In
this respect, the whalebone whales resemble the sloths, the turtle, and crocodile,
and in fact the whole series of air-breathing oviparous vertebrata, which  have
the  ear-drum convex externally.  In  the dolphins and porpoises, however, as
also in the narwhale, the membrana tympani is concave externally, as in other
Mammalia.]
  f [This connexion between the membrana tympani and  the malleus is denied
by Sir Everard Home, who wrote a paper and gave two plates in support of his
opinion.   After quoting  Mr. Hunter's description, he  says, " the fact is, that
there is no connection whatever between the membrana tympani and the malleus;"
and adds, that " this circumstance forms the great peculiarity  in the  organ of
hearing in  this species of whale (Balxna Mysticetus, Linn.)."  So singular an
anomaly as the absence of any communication between  the membrana tympani
and the ossieula  auditus, would, independently of our  interest in  the character of
Hunter as  an accurate observer, have  induced us to spare no pains to test the
conflicting statements with the facts themselves.  It fortunately happens that the
preparations figured by Home  are preserved (No. 1598 a. Physiological Series,
Hunterian  Museum) ;  and after a careful examination of  them, we find the fol-
lowing to be the true structure of the parts in question.  The membrane marked
cin Home's figure  (Phil. Trans., 1812, pi. II.) is continuous  at d with e, the
convex projection of the membrana tympani; whereas, the edge of the shadow
is so strong in the figure as to cause it to appear as if c and e were separate mem-
branes, as  Home describes them to  be: they are, however, parts of the same
membrana tympani, the attachment of which is  extended inwards beyond the cir-
cumference of the  termination of the bony meatus auditorius.  The triangular
ligament proceeding from the  handle of the malleus, and which is common to
all  the Cetacea, is  attached  not only to the plane portion of the ear-drum, but
to the whole of one side of the convex portion which projects into the meatus, and
is affected by every motion of that portion.]
  X [The malleus is anchylosed to the parietes  of the tympanum in the dugong.] 
          OBSERVATIONS ON THE STRUCTURE, ETC.       381

  The incus is attached by a small process to the tympanum, and
is suspended between the malleus and stapes.  The process by which
it articulates with the stapes is bent towards that bone.
  The stapes stands on the vestibulum, by a broad oval base.   In
many of this tribe, the opening from side to side of the stapes is so
small as hardly to give the idea of a stirrup.*
  The muscles which move these bones are  two in  number, and
tolerably strong.   One arises from that projecting part of the tym-
panum which goes to form the Eustachian tube, and running back-
wards is inserted into a small depression  on  the anterior part of
the  malleus.  The  use of  this muscle seems to be to tighten the
membrana tympani; but in those which have the malleus anchy-
losed with the tympanum, we can hardly conjecture its use.   The
other has its origin  from the  inner surface of the  tympanum, and
passing backwards is inserted into the stapes by a tendon, in which
I found a bone in the  large bottle-nose.  This  muscle  gives  the
stapes a lateral motion.  What particular use in hearing may be
produced by the action of these muscles, I will not pretend to say;
but we must  suppose, whatever motion is given to  the bones must
terminate in the movement of the stapes.
  The immediate organ of hearing is contained in a round bony
process, and consists of the cochlea and semicircular canals, which
somewhat  resemble the quadruped; but, besides  the two  spiral
turns of the cochlea, there is a third, which makes  a  ridge within
that continued from the foramen rotundum, and follows the turns
of the canal.
  The cochlea is  much larger, when compared  with  the semicir-
cular canals, than in the human species and quadruped.
  We may reckon two passages into the immediate organ of hear-
ing, the foramen  rotundum, and foramen ovale.   They are at a
greater distance than in the quadruped.  The foramen  rotundum
is placed much more on the outer surface of the bone, and not in
the cavity of the bony tympanum; but may be said to  communi-
cate with  the surrounding  cellular  part of  the  tympanum.   The
foramen rotundum,  which  is the beginning of one  of these  turns
(the scala cochleae, which is the central or inner canal), appears to
be only one end of a transverse groove, which is afterwards closed
in the middle, forming  a canal with the two ends open; so that
this foramen appears to have two beginnings; but the other  open-
ing is probably  only  a passage for blood-vessels going to  the
cochlea.
  From this foramen begins the inner turn of the cochlea, which is
the  largest, especially at its beginning; the other begins from  the
vestibulum.   The cochlea is a spiral canal coiled within itself, and
divided into two by a thin spiral bony plate, which  is completed in
the  recent subject, and forms two perfect canals.
  In the recent subject, the foramen rotundum  is  lined with  the

   * [In the Delphinus Leucas, the stapes is imperforate, as in the walrus.] 
382          HUNTER ON THE ANIMAL CECONOMY.
membrane of the tympanum, which terminates in a blind end, form-
ing a  kind of membrana cochleae.   The other opening, in the
recent subject, communicates with the spiral turn, beyond the mem-
branous termination of the foramen rotundum.
  The foramen ovale has a little projection inwards all around, on
which the stapes  stands:  within this is the vestibulum, which is
common to the other spiral turn of the cochleae, and the semicircu-
lar  canals; this canal of  the  cochlea (scala vestibuli) passes out
first in a direction contrary to  its general  course, but soon makes
a turn into the spiral.  It is round, and not merely a division of the
cochlea  into two by a septum,* but has a membrane of its  own,
which is  attached to the thin bony plate, and lines that part of the
cochlea in such a manner  as to retain its structure when the bone
is removed.  The cochlea  in some completes one turn and a half;
in others, more.f   It is not a spiral on a plane, or  cylinder, but on
a cone.
  I have already observed, that by looking in at the foramen rotun-
dum, we see two small  ridges; the uppermost is  the swell of the
canal from the vestibulum just described ; the lower ridge, which is
also a canal, may be observed  just  to pass along the foramen be-
longing to this canal, close to the septum between  the two ; a cir-
cumstance, I believe, peculiar to this tribe.  Its  beginning is close
to the vestibulum, but  does not open from it, and passes along the
first-described spiral turn  to its  apex: when opened, it appears  to
be a canal full of small perforations, probably the passages of the
branches from the auditory nerve.
  This bony process has several perforations  in it; one of  them
large, for the passage of the  seventh pair  of nerves.  The size  of
the  portio mollis,  before its entrance into the organ, is very large,J
and bears no proportion to  that which enters.   The  passage for
this nerve is very wide, and seems to have an irregular blind coni-
cal, and  somewhat  spiral,  termination;  its being spiral arise from
the  closeness to the  point of the cochlea.
  In the terminating part  there  are a number of perforations into
the  cochlea, and one into the semicircular canals,§ which afford a
passage to the different divisions of the  auditory nerve.  There is
a considerable foramen in  its anterior side  near the bottom, for the
passage of the portio  dura, and which  is  continued backward  to
the  cavity of the tympanum near the stapes, and emerges near the
posterior and upper  part of this bone.

  *  [i. e., It is a cylindrical canal, not semicylindrical as usual in quadrupeds.]
  f  [In the porpesse, the number of gyrations are two and a half.   Rudolphi de-
scribes two and a half gyrations  in the narwhale.  Rapp describes two  complete
gyrations in the Delphinus Delphis, and Pallas  the same number in the Delph.
Leucas.]
  X  [Tiedemann particularly notices  the large size of the acoustic nerve in the
dolphin.]
  § [The semicircular canals are chiefly remarkable for their small proportional
size; they were overlooked by Camper and Pallas, but were described by Com-
paretti two years later than Hunter, in  his " Observationes anatomicse de Anrein-
terna," Patavii, 1789.] 
                 OBSERVATIONS ON THE STRUCTURE, ETC.        383

                          Of the Organ of Seeing.

        The eye in this tribe of animals is constructed upon nearly the
      same principle  as that of quadrupeds, differing, however, in some
      circumstances;  by which it is  probably better  adapted to see  in
      the medium through  which  the  light is  to  pass.  It is upon the
      whole small for the  size  of the  animal,* which would lead to the
      supposition that their locomotion is not great; for I believe animals
      that swim are in this respect  similar to  those that fly; and as this
      tribe come to the surface of the medium  in  which they live, they
      may be considered in the same view with birds which soar; and
      we find  birds that fly to great heights, and move through  a con-
      siderable space in search of food, have their eyes larger in propor-
      tion to their size.
        The eyelids have but little motion,f and do not consist of loose
      cellular membrane, as in quadrupeds, but rather of  the common
      adipose membrane  of the body ;  the connection, however, of their
      circumference with the  common  integuments is loose, the cellular
      membrane being less loaded with oil, which allows of a slight fold
      being  made  upon  the  surrounding parts  in opening the eyelids.
      This is not to an equal  degree in them all, being less so in the por-
      poise than in the piked whale.
        The tunica conjunctiva, where it is reflected from  the eyelid  to
      the eyeball, is perforated all round by small orifices of the ducts  of
      a circle of glandular bodies  lying behind it.
        The lachrymal gland is small ;J  its use being supplied  by  those
      above  mentioned ; and the secretion from them  all I  believe to be
      a mucus similar to what is found in the turtle and crocodile.   There
      are neither puncta nor lachrymal duct, so that the secretion, what-
      ever it may be, is washed off into the water.
        The muscles which  open the  eyelids are very strong: they take -
      their origin  from the head, round the optic nerve, which in  some
      requires their being very long, and  are so broad as almost to make
      one circular muscle round the whole of the interior straight muscles  of
      the eye itself.   They may be divided into  four; a  superior, an in-
      ferior, and one at each angle : as they pass outwards to the eyelids,
      they diverge and become broader, and are inserted into the inside
      of the  eyelids almost equally all round.   They may be termed the
      dilatores  of  the eyelids;  and, before they reach their insertion,give

        * [The longest diameter of the eye of the mysticete whale and of the cachalot
      is two inches and a half, that of the piked whale four inches; but the eye owes
      much of its bulk to the thick sclerotic.  An affinity to the elephant and other
      large Pachyderms is manifested in this circumstance.]
        X  [The true Cetacea have no tarsel  cartilages, and no membrana nictitans,  or
      third eyelid ; this  is present in the  harbivorous species, as the dugong and ma-
      natee, and is represented by a thick duplicature  of the conjunctiva at the inner
      canthus in  the cachalot.]
1        ±  [This  is merely a larger development of the palpebral glands at the inner
      side of the  eyeball, and  should therefore be regarded as analogous to a Harderian
      gland.] 
384          HUNTER ON THE ANIMAL CECONOMY.
off the external straight muscles, which are small,* and inserted into
the sclerotic coat before the transverse axis of the eye: those may be
named the elevator, depressor, adductor, and abductor, and maybe dis-
sected away from the others as distinct muscles.   Besides these four
going from the muscles of the  eyelid to the eye itself, there are two
which are  larger, and inclose the optic nerve with the plexus.  As
these pass  outwards they become  broad, may in some be divided
into  four, and are inserted into the  sclerotic coat, almost all round
the eye, rather behind its transverse axis.f
   The two oblique muscles  are very long;  they pass through the
muscles of  the eyelids, are continued on  to the  globe of the eye,
between the two sets of straight muscles, and at their insertions are
very broad; a  circumstance which gives  great variation  to the
motion of the eye.J
   The sclerotic coat gives shape to the  eye, both  externally and
internally, as in other animals;  but the external shape and  that of
the internal cavity  are very dissimilar, arising from the great dif-
ference  in the thickness of this  coat in different parts.  The exter-
nal figure is round,  except that  it is a little  flattened forwards; but
that of  the cavity is far otherwise,  being made up  of sections of
various circles, being a little lengthened from the inner side to the
outer, a transverse  section making  a short  ellipsis.
   In the piked whale the long axis is two  inches and three-quarters,
the  short axis  two inches and one-eighth.§
   The  posterior  part of the cavity is a tolerably regular  curve,
answering to the difference in the two  axises;  but forwards, near
the  cornea, the scleretic coat turns  quickly in, to meet the cornea,

   * [The word "small" is  here used relatively to the palpebral muscles; for,
compared with the size of the eyeball the recti muscles in the Cetacea exceed in
bulk those of any other mammiferous animal.]
   f  [These shorter series of straight muscles correspond  with the choanoid mus-
cle or retractor  oculi  of other mammalia in which (man and  the quadrumana
excepted), it coexists with a membrana nictitans,  and is subservient to its mo-
tions by retracting the  globe  of the eye and displacing the adipose matter pos-
 terior to the eyeball, which  then presses  forward the third eyelid.   In the true
 Cetacea where there is no third eyelid some other uses must be  assigned for  the
 retractor oculi; it may perhaps assist by retracting the eyeball, in closing the
 ordinary eyelids, which have not the advantage of an orbicularis muscle for that
 purpose.  The retractor oculi is represented by  four short muscles in the turtle
 and tortoise, where the third eyelid is present, but has a special muscle for nic-
 titation.]
   ± [The superior oblique arises, as in other mammalia, from the posterior part
 of the orbit above the foramen opticum ; it passes forwards on the  external sur-
 face of the conical apertor  palpebrarum, which it perforates, and a kind of pulley
 is formed for it by this muscle and the cellular substance beneath it, the superior
 oblique  becoming at this  bend  partially  tendinous, but with little diminution of
 size ; it  then goes to be inserted into  the sclerotica, at such a direction to the ball
 of the eye as to act as a rotator to it, according to the use assigned  by Hunter to
 the oblique muscles in a previous  memoir.  The inferior oblique arises from the
 superior maxillary bone at the inner side of the orbital space.  Neither the direc-
 tion of this or of the superior oblique in the whales enables them to act as the anta-
 gonists  of the recti muscles.]
   § [See a view of the section of the eye of a whale in  Soemering's work, enti-
 tled, " De Oculorum sectwne horizontah, tab. ii.] 
            uaasun\ahuiso Ui^  THE STRUCTURE, ETC.        385

which  makes  this  part of the  cavity extremely flat, and renders
the distance between the anterior part of the sclerotic coat and the
bottom of the eye not above an inch and a quarter.
   In the piked whale the sclerotic coat, at its posterior part, is very
thick:  near the extreme of the  short axis it was  half an inch, and
at the long  axis one-eighth of  an inch thick.   In the  bottle-nose
whale (Hyperoodon) the extreme of the short axis was half an  inch
thick, and the extremes of the long axis about a quarter of an inch,
or half the other.
   The sclerotic coat becomes thinner as it  approaches to its union
with the cornea, where it is thin  and soft.  It is extremely firm in
its texture where thick,  and from  a transverse section would seem
to be composed of tendinous fibres, intermixed with something like
cartilage: in  this  section  four  passages for vessels  remain open.
This firmness of texture precludes all  effect of the straight muscles
on the globe of  the eye, by altering its  shape, and adapting its focus
to different  distances of objects, as  has been  supposed  to be the
case in the  human eye.
   The cornea makes rather a longer  ellipsis than the ball of the  eye ;
the sides of which are  not equally  curved, the  upper being  most
considerably  so.   It  is  a segment of a circle  somewhat  smaller
than that  of the eyeball, is soft  and very flaccid.*
   The tunica choroides resembles  that of  the  quadruped ; and its
inner surface  is of a silver hue,  without any nigrum pigmentum.f
   The nigrum  pigmentum only covers  the ciliary processes, and
lines the inside of the iris.J

   * [In the preparation  No. 1682, Physiological  Series, Hunterian Museum,
Hunter has displayed the laminated structure of the cornea of the whale  ; this
was known to Leeuenhoek, who succeeded  in  separating it into twenty-two
layers.  See Epist. Phys. p. 42, which are united by a fine cellular tissue.]
   f [The choroid in the cetacea is easily separable into two vascular laminae, of
which the outermost is of a blackish  colour, and is composed of larger  vessels,
connected by  cellular membrane, which gives it a tomentose appearance;  the
innermost (membrana rhuischiana) is equally vascular, of a pale colour, dense,
but thinner, most delicately villous and lined by a remarkable tapetum of a bluish-
white colour in the whale, with a greenish  and somewhat yellowish tinge  in the
cachalot, and  of a very light blue in the porpesse.  The  ciliary  zone is black,
broad, almost flat, composed of about seventy long processes, thick, flexous,
and extending their cylindrical apices almost as far as the anterior surface of the
lens.]
   X [When this layer of  pigment is removed from the iris, (as Hunter has done
in  the preparation 1680, Physiological Series,)  the fibrous structure of  the pos-
terior part of the iris becomes very apparent;  the outer series of fibres converge
 towards the margin of the pupil, where they are concealed by the sphincterfibres
 which surround that part; these latter elliptically disposed fibres are stronger than
the radiated ones.  The posterior fibrous coat of the iris may be separated without
 much difficulty from the anterior vascular layer. This consists chiefly of the
 branches of the two long ciliary arteries, which bifurcate opposite the long axis
of the pupil, and, the opposite branches anastomosing, form a canal which sur-
 rounds the  pupil.   Numerous tortuous or wavy branches radiate from this canal
 towards the outer margin of the iris.
   In the preparations No. 1680 and 1683 the structure of the,iris in  the whale is
 beautifully shown.
   The choroid is puckered up into numerous minute folds, which form the ciliary
                                   34 
3S6           HUNTER ON THE ANIMAL CECONOMY.
   The retina appears to be nearly similar to that of the quadruped.
   The arteries going to the coats of the eye form a plexus passing
round the  optic nerve, resembling  in  its  appearance that of  the
spermatic  artery in the bull and some  other animals.*
   The crystalline humour  resembles that  of  the quadruped;  but
whether it is very  convex or flattened I cannot  determine, those I
have examined having been kept too long to preserve their exact
shape and size.f   The vitreous humour adhered to  the retina at the
entrance of the optic nerve.
   The optic nerve is very long in some species, owing  to  the vast
width of the head. J
   I shall not at present consider the eye  in animals of this tribe, as
it  respects the power of vision, that being performed  on a general
principle  common to every animal inhabiting the  water;  more
especially  as I am  only master of the  construction  and  formation
of the coats, and not of the size, shape, and densities  of the humours;
yet from reasoning we must suppose them to  correspond with the
shape of  the eye, and the  medium  through  which  the light is to
pass.
                   Of the Parts  of Generation.

   The parts of generation in both   sexes  of this order of animals
come nearer in form to those of the ruminating than of any others,
and  this similarity is, perhaps, more remarkable in  the female than
in the male, for their situation in the male must  vary on  account
of external form, as was before observed.
   The testicles retain the situation in  which  they were formed, as
in those quadrupeds in which they  never come down into the scro-
tum.§   They are situated near the  lower part of the  abdomen,  one
on each side, upon the two great  depressors of the  tail.   At  this
part of the abdomen the  testicles come in  contact with the abdomi-
nal muscles anteriorly.||
zone; of these folds every  third, fourth, or fifth becomes  enlarged,  and is
extended forwards in the form of a wrinkled process about three lines in length,
compressed  laterally, and terminating somewhat obtusely ; between these larger
ciliary processes, which are about seventy in number, there are shorter processes
of a similar structure.]
  * [See prep. No. 1679, Physiological Series, Hunterian Museum.]
  t [The crystalline lens is inclosed in  a strong capsule, is remarkably globose,
rather more flattened anteriorly  than posteriorly,  placed at a very small distance
from the cornea, and  accordingly diminishing the space for  the aqueous, while
it  increases  that for the vitreous humour.   In the preparations of the crystalline
lens  in  the Hunterian Museum, preps. Nos. 1658-1687, the nucleus is  seen
to be excentnc, and situated on the posterior half of the  lens, and is of a  dark
colour.]
   X  [When  this  nerve  is divided transversely, and  the medullary substance
squeezed out, the neunlema does not present  the form of tubes, but of numerous
septa, which converge from the circumference to the centre of the nerve ]
   § [In this respect however the cetacea differ from the ruminants, and resemble
the elephant and the hyrax amongst the pachyderms.]
   || [At  the period of sexual  excitement  the  testes acquire  a great size.   In a
male porpoise I found  them occupying almost entirely the posterior fourth'part of 
            OBSERVATIONS ON THE STRUCTURE, ETC.         387

  The vasa deferentia pass directly from the epididymis behind the
bladder, or between it and the rectum, into the urethra ;  and there
are no bags similar to those  called  vesiculas seminales in certain
other animals.*
  The structure of  the penis is nearly the  same in them all, and
formed much upon the principle of  the  quadruped.   It is made up
of two crura, uniting into one corpus cavernosum,  and the corpus
spongiosum seems first to enter  the  corpus cavernosum.  In the
porpoise, at least, the urethra is found nearly in the centre of the
corpus cavernosum; but towards the glans  seems  to separate or
emerge from it, and becoming a distinct spongy body, runs  along
its  under  surface, as in  quadrupeds.   The  corpus  cavernosum in
some is broader from the upper part to the lower than from side to
side; but in the  porpoise  has the appearance  of being  round,
becoming smaller  forwards, so as to  terminate almost in a  point
some distance from  the  end of the penis.f  The glans  does not
spread  out as  in  many quadrupeds, but seems to  be merely a
plexus of veins covering the  anterior end of the penis, yet is ex-
tended a good  way further on, and is in some  no more  than one
vein deep.
   The  crura penis  are attached to  two bones, which  are nearly in
the  same situation  and in the same  part of the pelvis as those to
which the penis is attached in quadrupeds ; but these bones are only
for the insertion of the crura, and not for the support of any  other
part, like the pelvis in those animals which have posterior extremi-
ties, neither do they meet at the fore part, or join the vertebras of
the back.J

the abdominal cavity ; they measured each nine inches in length and four  inches
in the shortest diameter, and weighed together four pounds  avoirdupois.  The
corpus Highmorianum occupied the middle or axis of the gland, as in all testes
which are subject to considerable enlargement at the period of the rut; and the
membranous septa radiate from this body to the tunica albuginea.]
  * [The epididymis in the porpoise is of an elongated triedral form; the broadest
 facet is connected by a duplicature of peritonaeum to the testes;  the connexion is
close, except at the lower part of the gland, where the membrane is half an inch
broad.  The vas deferens continues to be convoluted, as in other testiconda, to
within two inches of its termination in the dilated bulbous part of the urethra : the
lining membrane of the terminal two inches of the vas deferens is denser, and of
a less glandular structure than the preceding part.]
  f [The corpus cavernosum  is remarkable for the thickness of its fibrous sheath,
which equals that of the contained erectile tissue; the fibres composing the  sheath
affect distinctly two directions, the external ones running longitudinally, the in-
ternal circularly.]
  J [These bones are of an elongated form, and are regarded by Cuvier as analo-
gous to  the iliac bones; but as they give attachment to the crura penis, and as
the erectores penis arise from  their whole outer and posterior surfaces, they would
seem to be rather the  homologues of the ischia. A strong tendon is continued,
in the porpoise, from the anterior and internal extremity of each bone, descends
obliquely inwards, and after the course of an inch and a half expands into  a mus-
cular belly, which joins its fellow in the mesial line  behind the rectum.  Below
this fleshy belly on each side  there is an  oval, flattened, slightly concave bone.
The commencement of the urethra is surrounded by thick capsule of muscular
fibres, which arise from the inner and anterior part of the ischia, and  from the 
388          HUNTER ON THE ANIMAL CECONOMY.
   The erectores  penis are  very strong muscles, having an origin
 and insertion similar to those of the human subject.
   The acceleratores muscles are likewise very strong; and there
 is a strong and long muscle, arising from the anus, and passing for-
 wards to the bulb of the penis, that runs along the under surface of
 the urethra,  and is at last lost or inserted in the corpus spongiosum.
 This muscle draws the penis into the prepuce, and throws that part
 of the penis that is behind its insertion into a serpentine form.   It is
 common  to  most animals that  draw back the penis  into what is
 called the sheath,  and may be called the retractor penis.
   In all the  females  which I have examined, the parts of genera-
 tion are very uniformly the  same, consisting of the external open-
 ing, the vagina, the uterus, fallopian tubes, fimbriae, and ovaria.
   The external opening  is  a  longitudinal  slit, or oblong opening,
 whose edges meet in  two  opposite points, and the sides are rounded
 off, so as to  form  a kind of  sulcus.   The skin and parts on each
 side of this sulcus are of a looser texture than on the common sur-
 face of the animal, not being loaded with oil, and allowing of such
 motion of one part on another, as admits of dilatation and contrac-
tion.   The vagina passes upwards  and backwards  towards  the
loins, so  that its  direction is diagonal respecting the cavity  of  the
abdomen,  and then divides into the two horns, one on each side of
the loins; these afterwards  terminating in the fallopian tubes, to
which the ovaria are attached.   From each ovarium there is a
small fold of the peritorjasum, which passes up towards the  kidney
of the same side, as in most  quadrupeds.
   The inside of the vagina is smooth for about one-half of its length,
and  then  begins to form something similar to valves projecting to-
wards the mouth  of the vagina, each like  an os tineas; these are
about  six, seven, eight, or nine  in number.  Where they begin to
form, they hardly  go  quite round, but the last arc complete  circles.
At this part too the vagina becomes smaller, and gradually  de-
creases in width to its termination.*
   From the last projecting part,  the passage is continued  up to  the
opening of the two horns, and the inner surface of this last part is
thrown into longitudinal rugas, which are continued into the horns.
Whether this last part is to be  reckoned common uterus or vagina,
and that the  last valvular part is to be considered as os tineas, I do
not know  ; but from its having the longitudinal rugae, I am inclined
to think it  is  uterus, this structure appearing to be intended for dis-
tinction.!

inner surface of the oval bones above mentioned.  These fibres seem, therefore,
 to correspond  with Wilson's muscle combined with the muscular part of the
 urethra. They envelope a glandular substance analogous to a prostate.]
  * [A muscle  arises, on  each side, from the whole length of the ischial bone, and
passing inwards is inserted into the external surface of the vagina, and into the
crura of the clitoris.  This body is  situated like a projecting ridge, without  any
preputial fold, between the thin labiae.  On each side of  the clitoris within the
mouth of the vagina, are the orifices of sinuses, analogous to the canals of Malpighi
in Ruminantia.]
  f [From the  os tincae, which Hunter calls the last projectingpartof the vagina 
OBSERVATIONS ON THE STRUCTURE, ETC.        389
   The horns are an equal division of this part;  they make a gentle
 turn outwards, and are of considerable length.   Their inner surface
 is thrown into longitudinal rugas, without any small  protuberances
 for the cotyledons to form upon, as in those of ruminating animals ;*
 and  where they terminate, the fallopian tubes begin.
   In the bottle-nose whale (Hyperoodon), where the fallopian tubes
 opened in the horns of the uterus, they were surrounded by  pendu-
 lous bodies hanging loose in the horns.
   The  fallopian tubes, at  their termination  in  the  uterus, are re-
 markably small for  some inches, and  then  begin to dilate  rather
 suddenly;  and the nearer to  the mouth the  more this dilatation
 increases, like the  mouth of a French  horn, the termination  of
 which  is  five  or  six  inches in diameter.f   They are very full of
 longitudinal rugas through their whole length.
   The ovaria are oblong bodies about  five inches  in length, one
 end attached to the mouth of the fallopian tube, and the other near
 to the horn  of the uterus.J  They are irregular on  their  external
 surface, resembling a capsula renalis or  pancreas.   They have  no
 capsula, but what  is formed  by the long  fallopian tube.
   How the male  and female  copulate,  I do  not  know;  but it is
 alleged that their position in the water is erect at that time, which
 I can readily suppose may be true ; for otherwise, if the connection
 is long, it would interfere with  the act  of respiration, as  in any
 other position the upper surface  of the heads of both could not be at
 the  surface of the water at the same time.  However, as in the
 parts of generation  they most resemble those bf the ruminating kind,
 it is possible they may likewise resemble  them in the duration of the
 act of copulation;  for, I believe, all the ruminants are quick  in this
 act.
   Of their uterine  gestation I as yet  know nothing;  but it is very
 probable that they have only a single  young one at a time, there
 being only two nipples.^   This seemed to be the case with the bot-
 to the beginning of the  division of the uterus, in  the porpoise, is about two inches.
 The uterus is lined with a very smooth mucous membrane; a  thin layer of cel-
 lular substance separates this from the  muscular tunie, in which the circular
 fibres  may be clearly discerned.  The  external tunic is derived from  the  peri-
 toneum which forms the broad ligaments.]
  * [The fcetus has neither placenta nor colytodons, but, as in the hog and camel,
 the general vascularity  of the chorion is subservient to its nutrition and respiration.
 The allantois is coextensive in its development with the chorion, and both extend
 into the horns of the uterus.]
  t [The margin of this opening, in the porpoise, is entire, without fimbriated
 processes.]
  J [In the porpesse the ovaria are attached to the ovarian ligament, and are situ-
ated half way between the expanded orifice of the fallopian tube and the extremity
of the  uterine horn.]
  § [The dolphin  has  generally one, but sometimes two at a birth, according to
Aristotle. According to Pallas, the Beluga (Delphinus Leucas) brings forth two,
but the exception to the general rule may have been observed in this case; since
Fabricius describes the same species as being uniparous(Fauna Grcenlandica, p. 51).
The Greenland whale brings forth a single young one  in April.   The spermaceti
whale  produces one voung one every year, according to Mr. Beale (Obs.  on the
                                    34* 
390          HUNTER ON THE ANIMAL  CECONOMY.
tie-nose whale caught near  Berkeley,  which  had been seen for
some days with one young one following it, and they were both
caught together.                                              ..
  The glands for the secretion  of milk  are two, one  on each side
of the middle  line  of the belly  at  its lower part.  The posterior
ends, from which go out the nipples, are on each side of the open-
ing  of the  vagina,  in  small  sulci.   They are flat  bodies lying
between the external layer of fat and abdominal muscles, and  are
of considerable length,  but only one-fourth of that in breadth.
They are  thin, that  they may not vary  the  external  shape of  the
animal, and have a principal  duct, running in the middle through
the whole length of  the gland, and  collecting the smaller  lateral
ducts, which  are  made up of  those still smaller.  Some of these
lateral branches  enter the common trunk in  the direction of the
milk's passage, others  in  the contrary  direction, especially those
nearest to the termination of the trunk in the nipple.   The trunk is
large, and  appears to serve as  a reservoir for  the  milk,* and  ter-
minates externally in a projection, which is the nipple.   The lateral
portions  of the sulcus which incloses the nipple are composed of
parts looser in texture than the  common  adipose membrane, which
is probably  to admit of the elongation  or projection of the nipple.
On the outside of  this there is  another small fissure, which, I ima-
gine, is likewise intended to give greater facility to  the  movements
of all these  parts.
  The milk is probably very rich ; for in that  caught near Berke-
ley with its young one, the milk which  was tasted by  Mr. Jenner
and Mr. Ludlow,  surgeon,  at Sodbury, was rich, like  cow's milk
to which cream had been added.
  The mode in which these animals must suck would appear to be
very inconvenient for respiration, as  either the mother or young
one will  be prevented  from breathing  at  the  time, their  nostrils
being  in  opposite directions; therefore the nose of one must be
under water,  and  the time of sucking  can only be between each
respiration.   The act  of sucking  must likewise be different from
that of land  animals;  as in  them it  is  performed by the lungs
drawing the air from the mouth backwards into themselves, which
the fluid follows, by being forced into the mouth from the pressure
of the external air on its surface ; but in this tribe, the lungs having
no  connection with the mouth,  sucking  must be  performed by

Sperm. Whale, 8vo., p. 36).  Mr. F.  D. Bennett found in a gravid cachalot
a single fcetus fourteen feet in length, and  six in girth;  its position  in the
uterus was that ofa bent bow. (Zool. Proceed.,  Dec. 1836.)   When brought
forth the young cachalot is usually  twenty feet in length.  And we may observe
that the cetacea in general are remarkable for the large size of the fcetus at birth.
 Camper describes the  new-born porpoise as  being half the size of the parent.
 (Obs. Anatomiques  sur les Cetaces,  p. 147.)  The rudimental condition of the
 pelvis renders the birth easy.]
   * [From this reservoir the milk is injected into the mouth of the young by the
 action of powerful cutaneous muscles, arranged so as to compress the reservoir and
 dilated ducts of the mammary glands.] 
              ON THE ANATOMY OF THE JERBOA.          391

some action of the  mouth  itself, and by its having the power of
expansion.*
     NOTES ON  THE ANATOMY OF THE  JERBOA,
                      (Dipus Sagitta, Gm.)
 (Extracted from the Appendix to Russel's History of Aleppo, where they  are thus
                            introduced.)

  " Having met with nothing more on the internal  structure of the
jerboa than what is given  by Gmelin from M. Buffon (Hist.  Nat.
torn, xiii.), I applied to  my worthy friend  Mr. John  Hunter,  who
 very obligingly favoured me with the following circumstances from
 his Adversaria by way of supplement.  He was not  certain whether
 the animal he  dissected was from Asia or Africa."
   ___The meatus auditorius  was large  like that of a bird.   The
 tympanum was also large.f   There are two venae cavas superiores.
 The caecum was four inches in length; it makes a  close turn  upon
 itself,  and gradually diminishing in size,  terminates  in  an obtuse
 point.   The colon, which  is large at its beginning,  passes first up-
 wards upon the right side, and  before crossing the abdomen on the
 left, makes a little  fold upon itself; it then crosses the  spine, and
 making another fold shorter than the former, it passes the left side
 and commences rectum.
   The lower part of the abdomen lies upon the anterior part of the
 pubes, and the bend of the penis is seen  within the  cavity of the
 abdomen, making  a little projection, as it were, between the origin
 of the two musculi recti.  The penis in a flaccid state lies reverted
 upon itself, but when in erection has a bone   on each side of the
 part projecting, in the same  manner  as  in  the guinea-pig.   The
 prepuce is furnished with a number of glands which secrete a thick
 mucus.   The  testicles  are situated on each side of the symphysis,
 and can  occasionally lie  in the rings of  the  abdominal muscles,
 which are very large,  but can  never descend much further, there
 being no scrotum  for their reception.  The vesiculae seminales are
 two  long bags, which  make a turn upon themselves.  The  anus
 is bent downwards towards the parts of generation.J

   * [Aided, as in the Marsupiata and Monolremata,  by muscular actions on the
 part of the parent tending to expel the milk.]
   i [See the Preparation No. 1599 Physiological Series, Hunter Museum, which
 is most probably the part here described, and if so, proves the description to be
 of the Dipus Sagitta.]
   X [These short and simple notes  are interesting as an example ot tne matter
 composing the lost " Adversaria," or manuscript notes of Hunter.  The compari-
 son which he makes with reference to the structure of the ear-passage shows that
 he was alive to those interesting points of structure which are indicative ot the
 natural affinities of different groups of animals.  The jerboa not on y  resembles
 the bird in the large  size of the meatus auditorius,  but also (together with the 
392
HUNTER ON THE ANIMAL  CECONOMY.
35. ANATOMICAL DESCRIPTION OF THE  AMPHIBIOUS
           BIPES  OF  ELLIS,  (Siren Lacertina, Linn.)

                     BY MR.  JOHN HUNTER, F.R.S.*

   The tongue is broad and has very little  motion.   It has a bone
similar to that in birds, turtles, &c.  On the posterior and  lateral


whole order of Rodentia) in the unanchylosed state of  the  tympanum with the
other elements of the temporal bone.  In the affinity to  the oviparous vertebrata
manifested in the two superior cavee, the genus Dipus agrees with the following
rodent  genera : Alactaga, Helamys, Echimys, Hystrix, Sciurus,  Pteromys,  Oryc-
teropus, Bathyergus, Lepus,  and Ccelogenys.  I  have  also shown that the same
structure characterizes the marsupial animals.   See Proceedings of the Zoological
Society, April 1832.]
  * [This  paper was read before the Royal Society June 5, 176G, and is interest-
ing from the  circumstance  of its being the first  which Hunter communicated to
that learned body, as well as from its being the earliest contribution to the anato-
my of one of the most singular tribes of animals at present in existence, viz. the
Batrachiaperennibranchiata, or true  Amphibia.   The sirens dissected by Hunter
were brought from South Carolina in 1758, and  purchased along with other sub-
jects of natural history by  Mr. Hunter; the  specimens  described by Ellis were
transmitted to him by Dr. Alexander Gardner, of Charles Town, South Carolina.
The natives call the  siren  "mudiguana."  It is found  in swampy and muddy
places  by  the sides of pools, under the  trunks of old  trees that  hang over the
water.   The external description of the siren by Mr. Ellis is given in the expla-
nation  of the plate Iii., p. 23.
  Besides the siren, Mr. Hunter also obtained two other species of perennibran-
chiate  reptiles, dissections of whicn are preserved in his museum, and recorded
in his manuscripts under the names of " Kattewagoe" (the  Menopoma Alleghan-
niensis of Dr. Harlan)  and the "Amphibious  quadruped," since particularly
described  by Cuvier under the name of " Amphiuma."   The types of three
other genera of perennibranchiata  have subsequently  been described, and the
whole  tribe  is divided into those which  retain the external branchiae throughout
life, and those which  lose these vascular processes, but  retain the gill apertures.
  The  sirens  and menobranchus of the United States, the axolotl  of Mexico,
and the proteus of Hungary have external fimbriated branchiae, while the am-
phiuma and  menopoma have only the branchial arches and apertures, but not
external gills.  These genera are all perfectly distinct from each other both in their
external and anatomical characters, and it is only with respect to one of them, viz.
the axolotl, that any doubt still remains as to whether the gills  are permanent or
not.
   At the period of the discovery of  the siren it was natural  to suppose from the
analogy of the newt and salamander that it was a larva, representing an immature
stage of its existence, on which subject LinnjEus thus cautiously expresses him-
self in  a letter to Mr. Ellis.
   " Upsal, December 27, 1765.  I  received Dr. Garden's very rare two-footed
animal with gills and lungs.  The  animal is probably the larva of some kind of
Lacerta, which I very much desire that he will  particularly inquire into.
   " If it does not  undergo a change, it belongs to the  order of Nantes, which
have both lungs and gills ; and if so, it  must be a new  and  very distinct genus,
and should most probably have the name of Siren.
   "I  cannot possibly describe to you how much this two-footed animal has ex-
 ercised my thoughts; if it is a larva  he will no doubt find some of them with four
 feet.   It is not an easy matter to reconcile it to the larva of the lizard tribe, its 
ANATOMICAL DESCRIPTION, ETC.
393
parts of the mouth are  three  openings  on  each  side; these  are
similar to the slits of the  gills  in  fish, but the  partitions  do  not
resemble gills on their outer edges, for they have not the comb-like
structure.  Above* and close  to the extremity of each of these
openings  externally,  so  many processes arise, the  anterior  the
smallest, the posterior the  largest;  their anterior and  inferior edges
and extremity  are serrated, or  formed  into fimbriae;  these pro-
cesses fold down and cover the slits externally, and would  seem to
answer the purposes of the comb-like part of the gill in fish.
   At the  root of the tongue, nearly as far back  as these openings
reach,  the trachea begins  much  in  the  same manner as in birds.
It passes  backwards above the  heart, and there divides into two
branches, one going to each lobe of the lungs.   The lungs  are  two
long bags, one on  each side, which begin just behind  the heart,  and
pass back through the whole length of the abdomen, nearly as far
as the  anus.   They are largest in  the middle, and  honey-combed
 on the  internal surface through  their  whole length.   The heart
consists of one auricle and one ventricle.  What  answers to  the
inferior vena cava passes  forwards above, but  in a  sulcus of the
liver, and opens  into a bag similar  to  the pericardium;  this  bag

 fingers  being furnished with claws;  all  the larvas of lizards  that I  know are
 without them (" digitis maUcis").  Then also the branchiae  or gills are not  to be
 met with in the aquatic salamanders, which are probably the larvas of lizards.
 Further, the croaking noise or sound it makes does not agree with the larvas of
 these animals, nor does the situation of the anus.  So that  there is no creature
 that ever I saw that I long so much to be convinced of the truth as to  what this
 will certainly turn out to be."
   Dr. Pockells of Brunswick, who visited the Museum of the Royal College of
 Surgeons,  in 1820, perceiving  some specimens of Amphiuma, concluded  from
 their having 'four legs and no external gills that they were the adult  or perfect
 Siren,  and Rusconi  adopted this  opinion without further  investigation ; but
 Cuvier has shown that the Amphiuma differs from the Siren in its osteological
 structure, having in one species ten, and in another twenty-two additional verte-
 brae, while the construction of  the cranium and other parts of the skeleton are
 totally different: moreover the completely ossified state of the skeleton of the
 Siren, without the slightest vestige of posterior extremities, proves it to be neither
 the larva of an Amphiuma or of any other known Amphibian.
   See Rusconi, Descr. Anat. delle larve Salamandr'e, 4to.,  1817; Del Proteo An-
 guino, 4to., 1819 ;   and Amours des Salamandres, fol.  1826,  p.  12.   Cuvier,
 Recherches  sur les Reptiles douteux, in Humboldt's Obs. Zool., 4to., 1811-1827 ;
 Ossemens Fossiles, torn. v. pt. 2 :  Mem. du Mus., torn. xiv.  See also " A Notice
 of a Siren Lacertina^ kept alive at Canon Mills,  Edinburgh, for more than six
 years, in Jamieson's Journal, 1832,  p. 298.  From the observations made on
 this animal it appears that the branchiae are the respiratory organs most essential
 to its existence, and its death is supposed to  have been occasioned by the fim-
 briae of  the wills becoming completely dried and shrivelled up, in consequence
 of its accidentally falling out of  the box of water in which it was habitu-
 ally kept.  It ate worms, sticklebacks, and small minnows greedily ; and showed
 great alertness and sagacity in  concealing itself most accurately beneath afloating
 patch of frog-bit.
   * To avoid the confusion in our ideas which might arise from the use of the
 words anterior, posterior, upper, lower, &c, in the whole of this description the
 animal  is  considered in its natural  horizontal position,  so that the head is for-
 wards, the back upwards, &c. 
394           HUNTER ON THE ANIMAL CECONOMY.
surrounds the heart  and  aorta, as the  pericardium does in other
animals;  from  this  there is an  opening into a vein  which lies
above,  and upon the left of the auricle, which vein seems to receive
the blood from the lungs, gills, and head,  is analogous to the  supe-
rior vena cava,  and opens into the auricle, which is  upon the left of
the ventricle.   The aorta goes out,  passing for a  little way in a
loose spiral turn, then becomes straight, where it seems to be mus-
cular;  at this part the branches  go off,  between which there is a
rising within the area of the aorta like a  bird's tongue, with its  tip
turned  towards the  heart.*   The liver  is principally one  lobe,
pretty close to  the heart  at the fore part,  and passes back on the
right of the stomach and intestines; at its  anterior extremity on the
left  side  there  is  a  very  short lobe, ending abruptly.  The gall-
bladder lies in a fissure on the left side of  the liver near its middle;
there is no hepatic duct; the hepato-cystic  ducts, which seem to be
three in number, enter the  gall-bladder at  its anterior end or fundus,
and the cystic  duct  passes  out from the  posterior  end of the gall-
bladder, and terminates in  the gut, about half an inch from  the
pylorus.   The  oesophagus which  is pretty  large, passes back, and
is continued into  the stomach in  the same line.   The stomach at
the posterior end  bends a little to  the right, where  it terminates in
the pylorus.  The intestines pass back,  making many turns ;  at  the
posterior  end  they become pretty straight, forming what  may be
called the colon, or rectum, where they are a  little  larger, and run
to the anus in a straight direction.  At  the  beginning of this larger
part of the intestinal tube there is no valvular structure.  The spleen

  * This account of the venae  cavae opening into  the cavity of the pericardium
may appear incredible ; and it might be supposed that, in the natural state of the
parts, there is a canal of communication going from  one cava to the other, which
being broken or nipped through, in  the act  of  catching or killing the  animal,
would give the appearance above  described.   I can only say that the appearances
were what have been described in three different subjects which I have dissected;
and in all of them the pericardium was full of coagulated blood.  But besides the
smallness of the subjects, it may  be observed that  they had been long preserved
in spirits, which made them more unfit for anatomical inquiries.  They had been
in my possession above seven years.*
  a [There is no preparation in the Hunterian Collection demonstrative of the
structure described in the text, and it was in the dissection of the siren, instituted
with  the view to reconcile or account for Hunter's description of the heart, that
I was led to the discovery of the two distinct auricles in that animal.   (Trans.
Zool. Soc., vol. i., p. 213, April, 1834.)  The inferior vena cava terminates at the
lower part ofa large membranous sinus, which al60 receives the blood from the
two superior cavae by two separate orifices. The common trunk of the pulmonary
veins seems also to end in this sinus, but it merely traverses without communi-
cating with it, and finally opens  into  a distinct transverse auricular chamber,
which is not separated externally from the apparently single and capacious auri-
cle of the venae cavae,  which is characterized by numerous elongated fimbriated
processes.   The glistening fibrous coat  of the pericardium closely adheres to the
surrounding muscles as  in fish, so that  the absence of any detached bag sur-
rounding the heart, the magnitude of the auricle, and the peculiar passage of the
pulmonary veins through the great sinus of the venae cavae may have contributed
to mislead Mr. Hunter as to the real structure of the part.] 
        OF THE ELECTRIC  PROPERTY OF  THE TORPEDO.      395

is a very small but long  body;  its anterior end is attached to the
upper surface  of the stomach, and it  is continued  back  along the
left side of the mesentery, to which it adheres.  The pancreas is a
small body lying above the duodenum, and is attached also to the
mesentery.  The kidneys are  situated in  the  upper and posterior
part of the abdomen, having the rectum passing below and between
them, as in the snake, &c.  Below the rectum lies a long bag, like
a bladder; it adheres all along to the inside of the abdominal  mus-
cles,  and  its  mouth  opens  into  the rectum ; but whether it is the
bladder of urine or not I cannot  tell.   On  each side of the rectum,
close to the lungs, there is a body, the posterior end of which  rests
upon the anterior end of the kidney ;  whether  they are testicles or
ovaria I cannot pretend to determine, but should imagine that they
are either the  one or  the other.*
36. OF THE ELECTRIC PROPERTY OF THE  TORPEDO.

In a Letter from John Walsh, Esq., F.R.S., to Benjamin Franklin, Esq., L.L.D.
                    F.R.S., Ac. K. Par. Soc. Ext., &c.f

                                       Chesterfield Street, July 1, 1773.
     Dear Sir,
   I  am  concerned that other  engagements  have  prevented  me
from giving to the  Royal Society, before their  recess, a complete
account  of my  experiments on the electricity of the torpedo;  a
subject not only  curious in itself, but opening  a  large field for in-
teresting  inquiry,  both  to  the  electrician  in  his walk of physics,
and to all  who consider, particularly or  generally, the animal
oeconomy.
   To supply the deficiency in the best  manner  I am  now able, I
will request the favour of you to lay before the  Society my letter

  * [The ovaria in the siren are  irregularly shaped elongated somewhat com-
pressed bodies, becoming smaller at the two extremities.  In a siren of two feet
long they were each four inches in length, and half an  inch broad, both  situated
at the lower and back  part of the abdomen: the left about an inch nearer the
head, having a smooth surface outwardly, and moulded on the inner surface to the
convolutions of the intestine.   The stroma ovarii was crowded with very numerous
and minute ovisacs  of a whitish colour, and was  studded here and there with
larger drops ofa dark-coloured oil.  The oviducts extend from  the cloaca, in the
form of broad, flattened, membranous canals, to near the anterior ends of the ovaria,
where they alter their form and become rounded tubes, each becoming folded upon
itself in broad close-set plaits, and terminating, without change of dimensions,  in
a longitudinal slit, which occupies part of the  anterior  surface of the last plait.
The oviducts are attached by a broad fold of peritoneum to the dorsal region  of
the abdomen.]
  f [This letter is prefixed to Mr. Hunter's description  of the Electric Organs, in
the Philosophical Transactions, vol. lxiii.] 
396
HUNTER ON THE ANIMAL CECONOMY.
from La Rochelle, of the 12th July, 1772, and such part of the let-
ter I afterwards wrote from Paris as relates to this subject.  Loose
and imperfect as these  informations are, for they were never  in-
tended for the public eye, they are still the most  authentic, and so
far the most satisfactory I  can at present offer,  since the notes I
made of the experiments themselves remain nearly, I am sorry to
say it, in that  crude and bulky state in which you had the trouble
to read them.

Letter from Mr. Walsh to Dr.  Franklin, dated La Rochelle, July 12,
                              1772.

  " It is with  particular satisfaction I make to you  my first  com-
munication, that the effect of  the torpedo appears to  be  absolutely
electrical;  by forming its circuit through the same conductors with
electricity, for  instance,  metals  and water; and by being  inter-
cepted by the same non-conductors, for instance, glass and sealing-
wax.  I will not at present trouble you with the detail of our expe-
riments, especially as we are  daily advancing  in them, but only
observe  that we have discovered  the back and breast of the animal
to be in  different states of electricity ; I mean in particular the  upper
and-lower surfaces of those two  assemblages of pliant cylinders of
which you have seen engravings in Lorenzini.*   By the knowledge
of this circumstance we have been able to direct his shocks, though
they  were very small, through a circuit  of four persons, all feeling
them ; likewise through a considerable length of wire held by two
insulated persons, one touching his lower surface, and the other his
upper.   When the wire was exchanged  for glass or sealing wax no
effect could be obtained, but as soon as  it was  resumed the two
persons became liable to the shock.  These experiments have been
varied many  ways and repeated times  without  number, and they
all determined the choice of conductors to be the same in the torpedo
as in the Leyden  phial.   The sensations likewise occasioned by one
and the other in the human frame are precisely similar.  Not only
the shock, but the numbing sensation which the  animal  sometimes
dispenses, expressed in French by the words engourdissement  and
fourmillement, may be exactly imitated with the phial, by means of
Lane's electrometer, the regulating rod  of which, to produce the
latter effect, must be brought  almost into contact with  the  prime
 conductor which joins the phial.  We have not yet perceived  any
 spark to accompany the shock, nor the pith balls to be ever aflected.'t

   * Observazioni intorno alle Torpedini di Stef. Lorenzini, 1678
 • ?f&»apP^ars t01J)e1thtfirst W*J°  ^marked these singular parts of the  torpedo
 in 1666.  Franc. Redi, Exper. Nat.              or             r
   f [Gardini and Galvani, and more recently Matteuci, concur in stating that
 they have seen a feeble spark from the discharge of a torpedo, but other philoso-
 phers have not been so successful.  The observations of Dr. John Davy on this
 point (Philos. Irans., 1834) particularly deserve attention.  He  experimented
 on very active fish, and varied his  trials, with every endeavour to obtain the re- 
        OF THE ELECTRIC PROPERTY OF THE TORPEDO.     397

Indeed, all our trials have been done on very feeble subjects, whose
shock was seldom sensible beyond the touching finger.  I remember
but one, of at least two hundred that I  myself  must have  received,
to have extended above the elbow.   Perhaps the Isle of Re, which
we are about to  visit,  may furnish us with torpedos fresher  taken
and of more vigour, by which a further insight into  these matters
may be had.  Our experiments have been chiefly in  the air, where
the animal was more open to our examination than in water.   It is
a  singularity that the  torpedo, when  insulated, should  be able  to
give to us, insulated likewise, forty or fifty successive shocks from
nearly the same  part, and  these with  little, if any, diminution  in
their force; indeed, they were  all very minute.  Each effort in the
animal to give the shock is conveniently accompanied with a depres-
sion of his eyes, by which even his attempts to give it to  non-con-
ductors can be observed.   The animal, with respect  to  the rest of
his body, is in a great  degree motionless, but not wholly so.   You
will please to acquaint Dr. Bancroft of our having thus  verified his
suspicion concerning the torpedo,*  and make any  other communi-
cation of this matter you may judge proper.  Here I shall be glad
to excite, as far  as I am able, both electricians and  naturalists to
push their inquiries concerning  this extraordinary  animal, whilst
the summer affords them the opportunity."
Extracts of a Letter from Mr.  Walsh to Dr. Franklin,  dated Paris
                         August 27, 1772.

  "......I spent a complete week in my experiments at the Isle
of Re, and had there every convenience for prosecuting them to their
extent, except that I was restrained by the jealousy of the govern-
ment from making  them where the  animal was caught.  At my
return to La Rochelle, I  communicated to the  members of the
Academy of that place  and to many of the principal inhabitants all
that I had  observed concerning  the  torpedo, in  the  intention of

quired result, but never procured a spark.  By means of Harris's electrometer,
however, he saw proof of the evolution of heat during the torpedo's discharge.
Abundant evidence of the chemical effects of animal electricity has been obtained
by the same philosopher.  He applied golden wires, one to the dorsal, the other
to the ventral surface of the torpedo, and passed the discharge through solutions
of nitrate  of silver, common salt, and superacetate of lead, and found that all
were decomposed, but the latter substance only when the fish seemed to put forth
all its energy, after being much irritated (Philos. Trans., 1832).  In resuming
the  inquiry instituted by Sir Humphry Davy, relative to the magnetical effects
of the torpedo's discharge, Dr. John Davy ascertains in the most satisfactory
manner that these effects were produced by animal electricity.  He placed eight
needles within a spiral of fine copper wire, containing about one hundred and
eighty convolutions, and having passed through this a single discharge from a
torpedo six inches long, the contained needles were all converted into magnets, and
the ends of the needles which were nearest the ventral  surface of the fish had
received the southern polarity.  See Phil. Trans., 1829.]
  *  Bancroft's Natural History of Guiana, p. 194.
                               35 
398          HUNTER ON THE ANIMAL CECONOMY.

stirring up a spirit of inquiry both  as to its electricity and general
ceconomy.
  "......The vigour of the fresh-taken torpedos at the Isle of
Re was not able to force the torpedinal fluid  across  the minutest
tract of air; not from one link of a small chain, suspended freely
to another; not through an almost invisible separation, made by the
edge ofa penknife, in a slip  of tinfoil pasted on sealing-wax.  The
spark,  therefore  (of course the  attendant snapping noise), was
denied to all our attempts to discover  it, not only in  daylight, but
in complete darkness.  I observed  to you in my last the singularity
of the torpedo being able, when insulated, to give to  an insulated
person a great number  of successive shocks: in this situation I have
taken no less than fifty  from him in the space of a  minute and  a
half.  All our experiments confirmed that his electricity was con-
densed in the instant of  its  explosion  by a sudden energy of the
animal, and as there was no gradual accumulation nor retention of
it, as in the case of charged glass, it is not at  all surprising that no
signs of attraction nor repulsion were perceived  in the  pith  balls.
In short, the effect of the torpedo appears to arise from a  com-
pressed elastic fluid, restoring itself to its equilibrium  in  the  same
way and by the same mediums as  the  elastic fluid compressed in
charged glass.  The skin of the animal, bad conductor as it is,
seems to be a better conductor of his electricity than  the thinnest
plate of elastic air. Notwithstanding the weak  spring of the torpe-
dinal electricity,  I was  able, in the  public exhibitions of my experi-
ments at La Rochelle,  to convey it through a circuit, formed from
one surface of the animal to the other, by two long brass wires
and four persons, which number at times  was  increased  even to
eight.  The several persons were made to communicate with each
other,  and the two outermost with the wires, by means of water
contained in  basins, properly disposed between them for the pur-
pose, each person dipping his  hands  in  the nearest basins, con-
nectively with his neighbour on either  side . '......
  " The  effect produced by the torpedo when in air appeared, on
many repeated experiments, to be about four times as strong as when
in water."
  A clear and succinct narrative of what passed at one of the pub-
lic exhibitions alluded  to in the last letter appeared in the  French
Gazette of the 30th  October, 1772.   As it came from a very re-
spectable quarter, not less so from the private  character of the gen-
tleman than from the public offices he held, I must desire leave of
the  Society to avail himself of such a testimony to  the facts I have
advanced by giving a translation of that  narrative.

Extract ofa Letter from the Sieur Seignette, Mayor of La Rochelle,
  and Second Perpetual Secretary of the Academy ^of that City, to
  the publisher of the French Gazette.

  " In the Gazette of the 14th August, you mentioned the discovery
made by Mr. Walsh, member of the parliament of England, and of 
        OF THE ELECTRIC PROPERTY OF THE TORPEDO.    399

the Royal Society of London.  The experiment of which I am
going to give you  an account, was made in the presence of the
Academy of this city.  A live torpedo  was  placed on  a table.
Round  another table  stood  five persons insulated.  Two brass
wires, each thirteen feet long, were suspended to the ceiling by silken
strings.   One of these wires rested by one end on the wet napkin
on which the fish lay ; the other end  was immersed  in a basin full
of water placed on the second table, on  which stood four others
basins likewise full of water.   The first person put a finger of one
hand in the basin in which the wire was immersed, and a finger  of
the other hand  in the second basin.   The second person put a finger
of one hand in this last basin, and a finger of the other hand in the
third; and so on successively, till the five persons  communicated
with one another by the water in the basins.   In the last basin one
end of the second wire was immersed ; and with the other end Mr.
Walsh touched the back of the torpedo, when the five persons felt
a  commotion which  differed in nothing from that of the Leyden
experiment, except in the degree of force.   Mr. Walsh, who  was
not in the circle of conduction, received no shock.  This experi-
ment was repeated several  times, even with eight persons, and
always with the same success.  The action of the torpedo is  com-
municated by the same mediums as that of the electric fluid.   The
bodies which intercept the action of the one, intercept likewise the
action of the other.  The effect produced by the torpedo  resemble
in every respect a weak electricity. "
   This exhibition of the  electric powers of the torpedo before the
Academy of La Rochelle, was  at a meeting held for the purpose
in my apartments, on the 22d July, 1772, and stands registered in
the journals of the Academy.
   The  effect of the animal was, in these experiments, transmitted
through as great an extent and variety of conductors as almost  at
any time we had been able  to obtain it, and the experiments  in-
cluded  nearly  all the  points in which its analogy with the effect  of
the Leyden phial had been observed.   These points were stated to
the gentlemen  present, as were the circumstances in which the two
effects  appeared to vary.  It was  likewise represented  to them,
that our experiments  had  been almost wholly with the animal in
the air; that its  action in water was a capital  desideratum; that
indeed  all as yet done was little more  than opening the door to  in-
quiry ;  that much remained to be examined by the electrician  as
well as by the anatomist; that as artificial  electricity had thrown
light on the natural operation of the  torpedo, this might in return,
if well  considered, throw  light on artificial  electricity, particularly
in those respects in which they now seemed to differ; that for me,
I  was about to take leave of the animal, as  nature had denied it to
the British seas ; and that the prosecution of these researches rested
in a particular manner with them, whose shores abounded with it.
   The  torpedo on this occasion dispensed only the  distinct, instan-
taneous stroke so well known by the name  of the  electric shock. 
400          HUNTER ON THE ANIMAL CECONOMY.
 That protracted but lighter sensation, that torpor  or numbness
 which he at times induces, and from which he takes his name, was
 not  then experienced from the animal; but it was imitated  with
 artificial electricity, and shown to be producible by a quick conse-
 cution of minute shocks.  This in the torpedo may perhaps be effect-
 ed by the successive discharge of his  numerous cylinders, in the
 nature ofa running fire of musketry : the strong single shock may
 be his general  volley.  In  the  continued effect, as well as in the
 instantaneous, his eyes, usually prominent, are withdrawn into their
 sockets.
   The same experiments, performed with the same torpedos,  were
 on the two succeeding days repeated  before numerous companies
 of the principal inhabitants of La Rochelle.   Besides the pleasure
 of gratifying the curiosity of such as entertained any on the sub-
 ject, and the  desire  I had  to excite a prosecution of the  inquiry,
 I  certainly wished  to give all possible notoriety to facts, which
 might otherwise  be deemed improbable, perhaps  by some of the
 first rank in science.  Great  authorities had given a sanction to
 other solutions of the phasnomena of the  torpedo; and  even the
 electrician  might not readily  listen  to assertions, which seemed in
 some respects to combat the general principles of electricity.  I
 had reason to make such conclusions from different conversations I
 had held on the subject with eminent persons both  at London and
 Paris. It is but justice to say, that of all in that class you gave me
 the greatest encouragement  to look for success in  this research,
 and even assisted me in forming hypotheses, how the torpedo, sup-
 posed to  be endued with electric properties, might use  them  in so
 conducting an element as water.
   After generally recommending to others an examination of the
electric powers of these animals when acting in water, I determined,
before I took my final leave of them, to  make some further experi-
ments myself with that particular  view ; since, notwithstanding the
familiarity in which we may be said to have live with them for near
a month, we had  never detected them  in the  immediate exercise of
their electric faculties against other fish, confined with them in the
same water, either in the circumstance  of attacking their prey, or
defending themselves from annoyance ; and yet  that they possessed
such a power, and exercised it  in a state of liberty, could not  be
doubted.
   A large torpedo, very liberal of his  shocks, being held with both
hands by his electric organs above and below, was briskly plunged
into water  to  the depth of a foot, and instantly raised an equal
height into air; and was thus  continually plunged and  raised, as
quick as possible, for the space of a minute.   In the instant his
lower surface touched the water in  his descent, he  always gave a
violent shock, and another still more violent in the instant of quitting
the water in his ascent; both which shocks, but particularly the last
were  accompanied with a writhing  in his body, as if meant to force
an escape: besides these two shocks from the surface of the water 
        OF THE ELECTRIC PROPERTY OF THE TORPEDO.     401

which may yet be considered as delivered in the air, he constantly
gave  at least two when wholly in the air, and  constantly one, and
sometimes two, when wholly in the water.   The shocks in the
water appeared, as far as sensation could decide, not to have near a
fourth of the force of those at the surface of the water, nor much
more  than a fourth of those entirely in the air.
  The shocks received in a certain time were not on  this occasion
counted by a watch, as they had been on a former, when fifty were
delivered in a minute and a half by the animal in an insulated and
unagitated state : but from the quickness with which the immersions
were  made, it  may be  presumed  there were full twenty of  these
in a minute;  from whence the number of shocks in that time must
have  amounted to above a hundred.   This experiment, therefore,
while it discovered the comparative force between a shock in water
and one in air, and between a shock delivered with greater exertion
on the part of the animal and one with less, seemed to determine,
that the charge of his  organs with  electricity was effected  in an
instant, as well  as the discharge.
  The torpedo  was then put into a  flat basket, open at top, but
secured by a net  with wide meshes, and in this confinement was let
down into the water about a foot below the surface :  being  there
touched through the  meshes with only a single finger on one of his
electric organs, while the other  hand was held at a distance in the
water, he gave shocks which were distinctly felt in both hands.
  The circuit for the passage of the effect being contracted to the
finger and thumb of one hand, applied above and below to a single
organ produced a shock, to our sensation, of twice the force of that
in the larger circuit by the arms.
  The torpedo, still confined  in the basket, being raised to within
three  inches of  the surface of the water, was  there touched with a
short  iron bolt,  which was held  half above and half in the water by
one hand, while the other hand  was dipped as before at a distance
in the water; and strong shocks, felt in both  hands, were thus ob-
tained through  the iron.
  A wet hempen cord being fastened to the iron bolt, was held in
the hand  above water,  while the bolt touched the torpedo; and
shocks were obtained through both those substances.
  A less powerful torpedo, suspended in a small net, being frequently
dipped into water and raised  again,  gave from the surface of the
water slight shocks through the net to the person holding it.
  These experiments in water manifested  that bodies immersed in
that  element might  be affected by  immediate contact with the
torpedo ; that the shorter the circuit in which the electricity moved,
the greater would be the effect;  and that the shock was communica-
ble from  the animal in water to  persons  in air through  some
substances.
  How far harpoons and nets, consisting of wood and hemp, could
in like circumstances, as it has been  frequently asserted, convey
the effect, was  not so particularly tried  as to enable us to confirm
                              35* 
402          HUNTER ON THE ANIMAL CECONOMY.

it.  I mention the  omission  in  the hope that some one may be in-
duced to determine the point by express trial.
  We convinced ourselves  on former occasions that the accurate
Kaempfer,*-who  so  well  describes the  effect of the torpedo, and
happily  compares  it with lightning, was deceived  in the circum-
stance that it could be  avoided by holding in the breath, which we
found no more to  prevent the shock of the torpedo when he  was
disposed to give it, than it would  prevent the shock of the Leyden
phial.
  Several  persons, foaming as many  distinct  circuits, can be af-
fected by one stroke of the animal, as well as when joined in a single
circuit.   For instance, four persons, touching separately his upper
and lower surfaces, were all affected ;  two persons likewise, after
the electricity had passed  through a wire  into  a basin of water,
transmitted it from thence, in two distinct channels, as their  sensa-
tion convinced  them, into another basin of water, from  whence it
was conducted, probably in a united state, by a single  wire.   How
much further the  effect might be thus divided and subdivided into
different channels was not determined ; but it was found to be propor-
tionably weakened by  multiplying these circuits, as it had been by
extending the single circuit.
   Something may be expected to be said of the parts of the animal
immediately  concerned in producing  the electrical  effect.   The
engraving which accompanies this letter, while it shows the general
figure of the torpedo, gives an internal view of his electric organs.
The Society will, besides, have  a full  anatomical description  of
these parts from the ingenious Mr. John Hunter, in a paper  he has
expressly written on  the  subject  at my request.  It  would there-
fore  be  superfluous for  me to say anything either in regard to  their
situation or structure.
   I have to observe, however, that in  these double organs resides
the electricity of  the torpedo, the  rest of his body appearing to be
no otherwise concerned in  his electrical effect than as conducting
it; that they are  subject  to  the  will of the animal; but whether,
like other double  parts so  controlable, they are exercised at times
singly as well as in concert, is  difficult to be ascertained by experi-
ment : that their  upper and under surfaces are capable, from a
state of equilibrium with respect  to  electricity, of  being instantly
thrown, by a mere energy, into an apposition of a plus and minus
state, like that of the charged phial: that when they are thus charged,
the upper surfaces of the  two are in the same  state of electricity;
as are the  under surfaces of the two, though in a contrary to that
of the upper; for  no shock can be obtained by an insulated person
touching both organs above, or both below : and  that the produc-
tion of  the effect depends solely on  an  intercourse being made be-
tween the  opposite surfaces of the organs, whether  taken singly
or jointly.                                                   °
* Kaempf. Amcen. Exct. 1712, p. 514. 
        OF THE ELECTRIC PROPERTY OF THE TORPEDO.    403

  All the parts bordering on the organs  act more or less as con-
ductors, either through  their substance  or by their  superficies.
While, an insulated person, placing two fingers on the same surface
of one or both organs, cannot be affected,  if he removes one of his
fingers to any such contiguous part he will  be liable to a shock ; but
this shock will not be near, perhaps not half so  violent as one taken
immediately  between the  opposite surfaces of  the organ, which
shows the conduction to be very imperfect.
  The parts which conduct the best  are the two great lateral fins
bounding the organs outwardly, and  the  space lying between the
two organs inwardly.  All below the double transverse cartilages
scarcely conduct at all, unless when the  fish  is just taken out of
water and is still wet, the mucus with which he is lubricated show-
ing itself as it dries to be  of an insulating nature.
  The organs themselves when uncharged appeared to be, not in-
teriorly we might suppose, but  rather  exteriorly, conductors of  a
shock.  An insulated person touching two torpedos, lying near one
another on a damp table, with  fingers placed, one on the organ of
one fish, and another on the organ of the  other, was sensible of
shocks, sometimes delivered by one fish, and sometimes by the other,
as might be discovered  by  the  respective winking of their  eyes.
That the organs uncharged served some way or other as conductors,
was confirmed with artificial electricity, in passing shocks by them,
and in taking sparks from them when electrified.
  The electric effect was never perceived by  us to  be attended
with  any motion or alteration  in  the organs  themselves, but was
frequently accompanied  with a little transient agitation along the
cartilages which surround both organs: this is not discernible in the
plump and turgid state of the animal while  he is fresh and vigorous :
but as his force decays, from the relaxation of his muscles, his car-
tilages appear  through  the skin, and then the  slight action along
them is discovered.
   May we not from all  these premises conclude, that  the effect of
the  torpedo  proceeds from  a  modification of the electric  fluid ?
The  torpedo resembles  the  charged phial  in  that characteristic
point of a reciprocation  between its  two surfaces.  Their effects
are transmitted by the same  mediums; than which there is not per-
haps a surer criterion to determine the identity of subtile matter:
they  besides  occasion  the same impression on our nerves.   Like
effects have like causes.  But  it may be objected, that the effects
of the torpedo, and of  the charged phial, are not similar in all their
circumstances ; that the charged phial occasions attractive or re-
pulsive dispositions in neighbouring bodies ;  and that its discharge
is obtained through a portion of air, and is accompanied with light
and sound ; nothing of which occurs with  respect to the torpedo.
   The inaction of the electricity of the animal in these particulars,
whilst its elastic force is so great as to transmit the effect through
an extensive  circuit and in  its course to communicate a shock,
may be a new phenomenon, but is no ways repugnant to the laws 
404          HUNTER ON THE ANIMAL CECONOMY.
of electricity, for here  too  the  operations of the animal may be
imitated by art.
  The same quantity of electric matter, according  as it is used in
a dense  or  rare  state,  will  produce the different  consequences.
For example, a small phial, whose coated  surface measures only
six  square  inches, will, on being highly charged, contain a dense
electricity capable of forcing a passage through an inch of air, and
afford  the  phenomena  of light,  sound, attraction,  and repulsion.
But if the  quantity condensed in this phial be made rare by com-
municating it to three large connected jars, whose coated  surfaces
shall form together an area four hundred  times larger than that of
the  phial (I instance  these jars because they are such as I use);  it
will, thus dilated, yield  all the negative phenomena, if I may so
call them, of the torpedo; it will not now pass the hundredth part
of that inch of  air which  in  its condensed state it sprung through
with ease; it will now refuse the minute intersection in the strip of
tinfoil;  the  spark and its attendant  sound, even  the attraction or
repulsion of light bodies,  will now be wanting;  nor will a point
brought  however near, if not in  contact, be able to draw off the
charge:  and yet,  with this diminished elasticity, the electric matter
will, to  effect its  equilibrium, instantly run through a considerable
circuit of different  conductors, perfectly continuous, and make us
sensible of an impulse in its passage.
  Let  me  here remark, that the sagacity  of Mr.  Cavendish in
devising and his  address  in  executing electrical  experiments, led
him the first to experience with artificial electricity, that a  shock
could be received from a charge which was unable to force  a pas-
sage through the least space of air.
  But  after the  discovery that a large  area  of rare electricity
would imitate the effect of the torpedo, it may be inquired, where
is this large area  to be found  in the animal 1  We here approach to
that veil of nature which  man cannot remove.  This, however, we
know, that from infinite division of parts infinite surface may arise,
and  even our  gross optics  tell us  that those singular organs, so
often mentioned, consist like our electric batteries of many vessels,
call them cylinders  or hexagonal prisms, whose  superficies taken
together furnish a considerable area.
37. ANATOMICAL OBSERVATIONS ON THE TORPEDO.*
                     BY JOHN HUNTER, F.R.S.

  I was desired some time since, by  Mr. Walsh, whose experi-
ments at La Rochelle had determined the  effect of the torpedo to
  * [This paper was read before the Royal Societv  Tnlv l 1773 ~„a  .v ,   ,
in the C3d volume of the Philosophical Transactions ]         '     pubhshed 
        ANATOMICAL OBSERVATIONS ON THE TORPEDO.     405

be electrical, to dissect and examine the peculiar organs by which
that animal produces so extraordinary an effect.  This I have done
in several subjects furnished to me by that gentleman.
   I am now desired by him to lay before the Society the observa-
tions I have made; and for the better understanding of them, to
present, on his part, a male and female torpedo in spirits; in the
latter of which  the electric organs are exposed in different views
and sections; likewise a copper-plate, which he took care  to have
engraved, exhibiting those organs.
   Of  the general  structure and  anatomy of the torpedo I say
nothing, since the animal does not differ very materially, excepting
in its electric organs (as they have been properly named  by Mr.
Walsh), from the rest of the rays, of which family it is well known
to be.  I will  only premise that the torpedo, of which I  treat, is
about  eighteen inches long, twelve broad,  and  in  its central or
thickest  part  two inches  thick;  which  is  nearly the size of the
female specimen  now presented to the Society, as well as of that
from which the plate was taken :  but where  there is any difference
in the organ arising from difference in  size, notice will be taken of
it  in this account.
   The electric organs of the torpedo are placed on each side of the
cranium and gills, reaching from  thence to the semicircular carti-
lages of  each great  fin,  and  extending  longitudinally from  the
anterior extremity of the animal to the transverse cartilage which
divides the thorax from the abdomen; and within  these limits they
occupy the whole space between the skin of the upper and of the
under surfaces: they are thickest at the edges near the centre of
the fish, and become  gradually  thinner towards the extremities.
Each  electric organ, at its inner  longitudinal edge, is unequally
hollowed, being exactly fitted to the irregular projection of  the cra-
nium  and gills.   The outer longitudinal edge is a convex elliptic
curve.  The anterior extremity of each organ makes the section of
a  small circle; and the  posterior extremity makes nearly a right
angle  with  the  inner  edge.   Each organ  is attached to  the sur-
rounding  parts by a close  cellular membrane,  and also by short
and  strong  tendinous fibres  which  pass  directly across from its
outer edge to the semicircular cartilages.
   They are covered above and Below by the common skin of the
animal, under which there is a thin fascia  spread over the whole
organ.  This is composed of fibres, which run longitudinally, or in
the direction of the body of the animal: these fibres appear to be
perforated in innumerable places,  which  gives  the fascia  the
appearance  of being fasciculated ; its edges all around are closely
connected to the skin, and at last  appear to be lost, or to degenerate
into the common cellular membrane of the skin.
   Immediately under this is another membrane exactly of the same
kind, the fibres of which in some measure decussate those of the
former, passing  from the middle  line  of the  body outwards and
backwards.   The inner edge of this is lost with the first described; 
406
HUNTER ON THE ANIMAL CECONOMY.
the anterior, outer, and posterior edges  are partly attached to the
semicircular  cartilages, and  partly lost  in  the  common  cellular
membrane.
  This inner fascia appears to be continued into the electric organ
by so many processes, and  thereby makes the membranous sides
or sheaths  of the  columns, which  are presently to be described ;
and  between these processes the  fascia covers  the end of each
column, making the outermost or first partition.
  Each organ of the fish under consideration* is about five inches
in length, and at the anterior end three in breadth, though it is but
little more  than half as broad  as at the posterior extremity.
  Each consists wholly of perpendicular columns, reaching from
the upper to the under surface of the body, and varying in their
lengths  according  to the thickness of the parts of the body where
they are placed; the  longest  column being  about an inch and a
half, the shortest about one-fourth of an inch in length, and their
diameters about two-tenths of an inch.
  The figures of the  columns are  very  irregular, varying accord-
ing to situation and other circumstances.  The greatest number of
them are either irregular  hexagons  or irregular pentagons; but
from the irregularity of some of  them  it happens that  a pretty
regular quadrangular column  is sometimes formed.  Those of the
exterior  row are  either quadrangular  or  hexagonal, having  one
side external, two lateral, and either one or two internal.  In the
second row they are mostly pentagons.
  Their coats are very thin, and seem transparent, closely connected
with  each other,  having a kind  of  loose network of tendinous
fibres, passing transversely and obliquely between the columns, and
uniting  them more firmly together.   These are  mostly observable
where the large trunks of the  nerves pass.   The columns are also
attached by strong inelastic fibres,  passing directly from one to the
other.
   The-number of  columns in  different torpedos of the size of  that
now offered to the Society appeared to be about 470 in each organ,
but the  number varies  according to the size of the fish.f  These
columns increase, not only in size, but in  number, during the growth
of the animal;  new ones forming  perhaps every  year on the ex-
terior edges, as  there they are much the smallest.  This process
may be similar to the formation of new teeth in the human jaw as it
increases.
   Each column is divided by  horizontal partition placed  over
each other, at very small distances, and  forming numerous inter-
stices, which appear to contain a fluid.  These partitions consist of
a very thin membrane, considerably transparent.   Their edges ap-
pear to be attached to one another, and the whole is attached by

  * [This specimen was eighteen  inches long, twelve inches broad, and in its
central or thickest part two inches thick.]
  f In a very large Torpedo, (see the preparation No. 2176, Physiological Series,)
the number of columns in one electric organ were 1182. 
         ANATOMICAL OBSERVATIONS ON THE TORPEDO.     407

a fine cellular membrane to the inside of  the columns.  They are
not totally detached from one another:  I have found them adhering
at different places by blood-vessels passing from one to another.
   The number of partitions  contained in a column of one  inch  in
length, of a torpedo  which had been preserved in proof spirit, ap-
peared on  a careful examination to be one hundred and fifty; and
this number in a given length of column appears to be common  to
all sizes in the  same state  of humidity, for by drying  they may
be greatly altered; whence  it appears probable that the increase
in the length ofa column, during the growth of the  animal, does
not enlarge the  distance between each partition  in proportion  to
that growth;  but that new partitions are formed, and added to that
extremity of the column from the fascia.
   The partitions are very  vascular;*  the arteries are branches
from the vessels of the  gills which convey the blood  that has re-
ceived the influence  of respiration.  They  pass along  with the
nerves to the electric organ, and enter with them ;  then they ramify
in every direction into innumerable small branches upon the  sides
of the columns, sending in from the circumference all  around upon
each partition small arteries, which ramify and anastomose  upon it,
and passing also from one partition to another, anastomose with the
vessels  of the adjacent partitions.
   The veins  of the electric organ  pass out close to the nerves and
run between the gills to the auricle of the heart.
   The nerves inserted into each electric organ arise by  three very
large trunks from the lateral and posterior part of the brain.   The
first of these in its passage outwards turns round a cartilage of the
cranium and  sends a few branches to the  first gill, and to the ante-
rior part of the  head, and then passes into the organ towards  its
anterior extremity.+   The  second  trunk  enters the giils between
the first and second openings, and  after furnishing it with  small
branches passes into the organ near its middle.  The third trunk,
after leaving  the skull, divides itself into two branches, which pass
to the electric organ through the gills; one between the second and

   * [See prep. 2176, which is the section ofa Torpedo, of very large size, taken
in Torbay in August, 1774.   It  weighed fifty-three pounds, was  four  feet in
length, two feet and a half in breadth, and  four inches and a half in thickness.
Mr. Hunter having received this fish in a recent state was enabled to inject it, and
thus demonstrate the vascularity of the electrical organs.]
   f [This nerve is a part of the third division of the fifth pair, and  does not
greatly exceed the  size of the corresponding nerve in other species of the ray
tribe; it  distributes branches  to  the  mucous tubes, which  are  fewer in
number in the torpedo than in the ordinary rays, before it penetrates the electric
oro-an.  The other great fasciculi of nerves correspond with the pneumogastric,
or'eighth  pair of nerves :  a large branch is continued from the most posterior to
the stomach, where it is spread over the great arch.  Dr. John Davy conjectures
that the superfluous electricity when not required for the defence of the animal
may be directed to this organ to promote digestion. In the instance of a Torpedo
which he preserved  alive for many days, and which was frequently excited to
give shocks,digestion appeared to have been completely arrested ; when it died,
a small fish  was found in its stomach, much in the same state in which it was
swallowed ; no portion of it had been dissolved.] 
408          HUNTER ON THE ANIMAL CECONOMY.
third openings, the other between the third and fourth, giving small
branches to the gills itself.   These nerves having entered the organs
ramify in every direction  between the  columns, and send in small
branches upon each partition, where they are lost.
  The magnitude and the  number of the nerves bestowed on these
organs, in proportion to their size, must on reflection appear as ex-
traordinary as the phenomena they afford.  Nerves are  given to
parts  either for  sensation  or  action.  Now if we except the more
important senses of seeing, hearing, smelling, and tasting, which do
not belong to the electric organs, there is no part even of the most
perfect animal which, in proportion to its size, is so liberally sup-
plied  with nerves; nor do the  nerves seem necessary for any sen-
sation  which can be  supposed to belong to the electric organs.
And with respect to  action, there is no part of  any animal with
which I am acquainted, however strong  and constant its natural
actions may be,  which has so great a proportion of nerves.
  If it be then probable that no nerves are not necessary for the
purposes of sensation or action, may we not conclude that they are
subservient to the formation, collection, or management of the elec-
tric fluid 1 especially as it  appears evident, from  Mr. Walsh's  ex-
periments, that the will  of the animal  does absolutely  control the
electric powers of its body, which must  depend on the energy of the
nerves.
  How far this may be connected with the powers of the nerves in
general, or how  far it may lead to an  explanation of  their opera-
tions,  time and future discoveries alone can fully  determine.
38. AN ACCOUNT OF  THE GYMNOTUS ELECTRICUS.*

                    BY JOHN HUNTER, F. R. S.

  To Mr.  Walsh, the  first discoverer of animal electricity, the
learned will be indebted for whatever the following pages may con-
tain, either curious or useful.   The specimen of the animal which
they describe was procured by that gentleman, and at his request
this dissection was performed and this account of it is communi-
cated.
  This fish on the first view appears very much like an eel, from
which  resemblance it has most probably got its name ; but it has
none of the specific properties of that fish.  This  animal  may be
considered, both anatomically and physiologically, as divided  into
two parts, viz., the common animal part, and a part which is super-
added, viz. the  peculiar organ.   I shall at present  consider it only
with respect to  the last, as the first explains nothing relating to the

  * [This paper was read before the Royal Society May 11, 1775, and published
m the 65th volume of the Philosophical Transactions.] 
         AN ACCOUNT OF THE GYMNOTUS ELECTRICUS.    409

other, nor anything relating to the animal ceconomy of fish in gene-
ral.  The  first, or  common  animal part, is so contrived as to ex-
ceed what was necessary for itself, in order to give situation, nou-
rishment, and most probably the peculiar property to the  second.
The last part, or peculiar organ, has an immediate connexion with
the first, the body affording it a situation, the heart nourishment, and
the brain nerve, and probably its peculiar powers.  For the first of
these purposes  the body  is extended  out in length, being much
longer than would be sufficient for what may be called its progres-
sive motion.   For  the real  body, or that part where the  viscera
and parts of generation lie, is situated, with respect to the head, as
in other fish,  and is extremely short, so that, according to the ordi-
nary proportions, this should be a very short fish.   Its great length,
therefore, seems chiefly intended to afford the surface for the sup-
port of the peculiar organ ; however, the tail part is likewise adapt-
ed  to the  progressive motion  of  the  whole and to  preserve the
specific gravity; for the  spine, medulla spinalis, muscles, fin, and
air-bladder* are continued through its whole length.  Besides which
parts there is a membrane passing from the spine to that fin which
runs along the belly or lower edge of the animal.   This membrane
is broad at the end next to the  head, terminating in a point at the
tail; it is a support for the abdominal fin, gives  a  greater  surface
of support for the organ, and makes a partition between the organs
of the two opposite sides.

                          The  Organs.

  The organs  which produce the peculiar effect of this  fish con-
stitute nearly one-half of that  part of the flesh in  which they are
placed, and perhaps make more than one-third of the whole  animal.
There are two pair of these organs, a larger and  smaller, one being
placed on each side.  The large pair occupy the  whole lower or
anterior, and  also  the lateral part of the body, making  the thick-
ness of the fore or lower parts  of the  animal; and run almost
through its whole length, viz., from the abdomen to near the end of
the tail.   It is broadest on the sides of the fish  at the anterior end,
where it incloses more of the  lateral  parts of the body, becomes
narrower towards the end of the tail, occupying less and less of the
sides of the animal, till at last it ends almost in a point.  These two
organs are separated  from one another at the upper part by the
muscles of the back which keep their posterior or upper edges at a
considerable  distance from one  another ;  below that, and towards
the middle, they are separated by the air-bag, and at their lower
parts they are separated by the middle partition.   They begin for-

  * [The Gymnotus electricus has two air-bladders, one of which, of an oval form
and bilobed, is  situated at the anterior part of the abdomen, beneath the oeso-
phagus ;  the other  is the elongated sac described  by Hunter, and  extended
through the posterior part of the body.  In another species, the Gymnotus xqui-
labiatus of Humboldt, the posterior elongated air-bladder is wanting.]
                               36 
410
HUNTER ON THE ANIMAL CECONOMY.
wards  by a pretty  regular  edge, almost at right angles with the
longitudinal axis of the body, situated on the lower and lateral parts
of the abdomen.  Their upper edge is a pretty  straight line, with
small indentations made by the nerves  and blood-vessels which
pass round it to the  skin.  At the anterior end  they  go as far to-
wards  the  back as the middle  line of the animal, but in their ap-
proach  towards the tail they gradually leave  that line, coming
nearer to the lower surface of the animal.  The general shape of the
organ,  on an external or side view, is broad at the end  next to the
head of the animal, becoming gradually narrower towards the tail,
and  ending there almost in a point.   The other surfaces of the
organ are fitted to the shape of the parts  with which  they come in
contact, therefore on the upper and inner surface it is hollowed to
receive the muscles of  the back.  There is also a longitudinal
depression on its lower edge, where a substance lies which divides
it from  the small organ, and which gives a kind of fixed point for
the lateral muscles of the fin.   Its most internal surface is a plane
adapted to the partition which divides the two organs from one
another.  The  edge next to the muscles of the back is very thin,
but  the organ  becomes  thicker and  thicker towards  the middle,
where  it approaches the centre of the animal.   It becomes thinner
again towards  the lower surface or belly,  but  that edge is  not so
thin as  the other.  Its union with the parts to which it is attached
is in general by a loose but pretty strong cellular membrane, except
at the  partition, to which it is  joined so close as to be almost inse-
parable.
  The  small organ  lies  along the lower edge of the animal, nearly
to'the same extent as the other.  Its situation is marked externally by
the  muscles which  move the  fin under which it lies,   its anterior
end begins nearly in the same line with  the large  organ, and just
where the fin begins.  It terminates almost insensibly near the end
of the tail, where the large organ also terminates.  It is of a trian-
gular figure, adapting itself to the part in which  it lies.   Its anterior
end is the narrowest part; towards the tail it becomes broader ; in
the  middle of  the organ it is thickest, and from thence becomes
gradually thinner to  the tail, where it is very  thin.  The two small
organs are separated from one another by the middle muscles, and
by  the bones upon which the bones of the fins  are articulated.  The
large and the small organ on  each  side are separated from one
another by a fatty membrane, the inner  edge of which is attached
to the  middle partition, and its outer edge is lost on the skin of  the
animal.  To expose the large organ to view nothing more is neces-
sary than to remove the skin, which adheres to it by a loose cellular
membrane; but to expose the small organ it is necessary to remove
the  long row of small muscles which move the fin.

                Of the Structure of  these Organs.
   The structure is extremely simple and regular, consisting of two
parts, viz., flat partitions of septa, and cross divisions between them. 
AN ACCOUNT OF THE GYMNOTUS ELECTRICUS.     411
The outer edges of these  septa  appear externally in parallel lines
nearly in the direction of the longitudinal axis of the body.  These
septa are thin membranes, placed  nearly  parallel  to one another.
Their lengths are nearly in the direction of the long axis, and their
breadth is  nearly the semi-diameter of the body of the  animal.
they are of different lengths, some being as long  as "the whole organ.
I shall describe them  as beginning principally at the anterior end
of the organ, although a few begin along the  upper edge, and the
whole, passing towards  the  tail, gradually terminate on the lower
surface of the organ ;  the  lowermost  at  their origin terminating
soonest.  Their  breadths  differ in different parts  of  the  organ.
They are in general broadest near the anterior end, answering to
the thickest part of the organ, and  become gradually narrower to-
wards the tail; however, they are  very narrow at their beginnings
or anterior ends.   Those nearest to the muscles of the back  are the
broadest, owing  to their  curved or oblique situation  upon these
muscles, and grow gradually  narrower  towards the lower part,
which is in a great measure  owing to  their becoming more trans-
verse, and also to the  organ becoming thinner at  that place.   They
have an outer and an  inner edge;  the outer is  attached to the skin
of the animal, to the lateral muscles of the fin, and to the membrane
which divides the  great organ  from  the  small, and the whole of
their inner edges are fixed to the  middle partition formerly described,
also to the air-bladder, and three or four terminate on that surface
which inclose the  muscles of the  back.  These  septa  are  at  the
greatest distance from one another at their exterior edges near the
skin, to which they are united ;  and as they pass from  the skin to-
wards their  inner attachments they approach one another.   Some-
times we find two uniting  into one.  On  that side next  to the mus-
cles of the back  they  are  hollow from edge to edge, answering to
the shape of those  muscles, but become  less  and less so towards
the middle of the organ, and from that towards the lower  part of
the organ they become curved  in  the other direction.  At  the an-
terior part of the large organ, where it is nearly of an equal breadth,
they run pretty  parallel to  one another, and  also pretty straight,
but where the organ becomes narrower it may be observed in some
places that two join or  unite into  one, especially  where a nerve
passes across.  The termination of this organ  at the tail is so very
small that I  could not  determine whether it consisted of one  septum
or more.  The  distances  between these  septa will differ in fishes
of different sizes. In a fish of two feet four inches in length I found
them 2V of an inch  distant from one another,  and the  breadth  of
the whole organ, at the broadest part, about an inch and a quarter,
in which place  were  thirty-four septa.  The small organ has the
same kind of septa, in length passing from end  to end of the organ,
and in breadth passing quite across; they run somewhat serpen-
tine, not exactly in straight lines.  Their outer edges terminate on
the outer surface of the organ, which  is in contact with the inner
surface of the external  muscle of the fin,  and their inner edges are 
412
HUNTER ON THE ANIMAL  CECONOMY.
in contact  with the centre muscles.   They differ very  much in
breadth from one another, the broadest being equal to one side of
the triangle, and the narrowest scarcely broader than the point or
edge.  They are pretty nearly at equal distances from one another,
but much nearer than those of the large organ, being only about 7B-
part of an inch asunder ; but they are at a greater distance from  one
another towards the tail,  in proportion  to  the increase of breadth
of the organ.  The organ is about half an inch in breadth, and  has
fourteen septa.  These septa, in both  organs, are  very  tender in
consistence, being easily torn.   They appear to answer the same
purpose with the columns in the torpedo, making walls or butments
for the subdivisions, and  are  to be considered as making so many
distinct organs.  These septa are intersected transversely by very
thin plates  or membranes, whose  breadth is the distance between
any two septa, and therefore  of different breadths in different parts,
broadest at that edge which is next to  the  skin, narrowest at that
next to the centre  of the  body, or to the middle partition which di-
vides the two organs from one another.   Their lengths are equal to
the  breadths  of  the  septa,  between  which  they  are situated.
There is a regular series of them continued from one end of any  two
septa to the other.  They appear to be so  close  as even to touch.
In an inch in  length there are about two hundred and forty, which
multiplies the surface in the whole to a vast extent.

                         Of the JVerves.
   The nerves in this animal may be divided into two kinds, the  first
appropriated  to the general purposes  of  life, the second for  the
management of this peculiar  function, and  very probably for  its ex-
istence.  They arise in general from the brain and medulla spinalis,
as in other fish, but those from the medulla are much larger than in
fish of equal  size, and larger than is necessary for  the common
operations of life.  The nerve which arises from the brain and passes
down the whole length of the animal  (which I believe exists  in all
fish) is larger in this than in others of the same size, and  passes
nearer to the spine.  In  the common eel it runs in the muscles of
the back, about midway between the skin  and spine.   In the cod it
passes immediately under the skin.   From its being larger in  this
fish than in others of the same size one might  suspect that  it  was
intended for supplying the organ in some  degree; but this  seems
not to be the  case, as I was not able to trace any nerves going from
it to join those from the medulla spinalis, which run to the organ.
This nerve is as  singular  an appearance  as any in this class of
animals; for surely it must appear extraordinary that a nerve should
arise from the brain to be lost  in  common parts while  there  is a
medulla spinalis giving nerves to the  same parts.   It must still re-
main one of the inexplicable  circumstances of the nervous system.*
   * [This remarkable nerve, the nervus lateralis, is, in the Gymnotus, a branch
of the nervus vagus. It does not exist in the myxine, but in the hio-her car-
tilaginous fishes it is largely developed.  In the rays it extends from'the occi-
put to the end of the tail, even where this, as in the Raia fasciata, is six  times 
          AN  ACCOUNT OF THE GYMNOTUS ELECTRICUS.     413

The organ is supplied  with nerves from the  medulla spinalis, from
which they come out in pairs between all the vertebre of the spine.
In their passage  from the spine  they  give nerves to the  muscles of
the back, &c.  They bend forwards  and outwards upon the spine,
between it and the muscles, and  send  out  small  nerves to the ex-
ternal surface, which join the skin near to the lateral lines.  These
ramify upon the skin, but are principally bent forwards between it
and the organ, into which they send  small branches  as they pass
along.   They seem to  be lost in these two parts.   The  trunks  get
upon the air-bladder, or rather dip between it and  the muscles of
the back, and continuing their course forwards upon that bag, they
dip in between  it  and  the  organ, where  they divide  into smaller
branches;  then they get upon  the middle partition, on which they
continue to divide into still smaller branches; after which they pass

the length of the body;  and in the trunk the two nerves exceed the size of the
spinal chord.
   In  osseous fishes  it is relatively smaller, and in some species, as the cod, is
formed by a combination ofa branch of the fifth with a filament of the eighth or
nervus vagus.
   Besides the  class of fishes (with the exception of the  myxine), the lateral
nerve is also present in those reptiles which preserve throughout life the external
branchiae or  the branchial  apertures, and which reside habitually in water, and
move, like fish, by the actions ofa caudal fin.  In the Menobranchus the nervus
lateralis forms a large branch  of  the nervus vagus, and passes superficially be-
neath the skin as far back as the middle of the tail, where  it joins the filaments
of the spinal  nerves.   In the proteus the nervus vagus sends off* on each side
two nervi laterales, one deep-seated, the  other superficial.  In the menopome
the lateral nerve  is likewise  present, but is much  more  delicate than  in the
Perennibranchiata with  external  gills.   In the larva of the Rana paradoxa the
lateral nerve may be observed beneath the skin in the longitudinal fissure which
separates the two large muscular fasciculi of the tail on  each side.  After the
full formation of the  anterior extremities this nerve becomes gradually more
attenuated, and  finally disappears with  the absorption of  the tail.  It does not
exist in  the anourous batrachia.  We may thus perceive a relationship of co-
existence to subsist between these enigmatical nerves and branchial respiration.
This  imperfect  kind of respiration  is assisted by  the vascularity and active
powers of excreting  mucus in the whole or a part of the external tegument.   In
the osseous fishes a linear series of mucous follicles is extended along each side
of the body, and  the lateral nerves, which  run  parallel wiih these lines give
numerous branches to the mucous sacs and the neighbouring skin ; and in  the
Perennibranchiata the lateral  nerves are exclusively distributed  to the  skin:
hence they might be termed the cutaneous respiratory nerves.  They do not sup-
ply the muscles along which they pass;  these derive their  nervous energy from
the ordinary spinal  nerves.   When  irritated  or galvanized the  lateral nerves
excite no contractions in the muscles; they  are therefore  not analogous to the
spinal accessory nerves in the mammalia.   In the Gymnotus  Mr. Hunter was not
able to trace any nerves going from the  lateral nerve to join those from the me-
dulla spinalis which supply the electric organ, but it anastomoses with the spinal
nerves which supply the caudal  fin.  And in  the cod, where this anastomosis
takes place at each of the numerous fins, Mr.  Swan conjectures that its function
may be to produce sympathy and harmonious cooperation, and to regulate and
produce, independently of the will, the action of the muscles  of these parts. (See
his accurate  and  beautiful Illustrations of the Comparative Anatomy of the
Nervous  System, p. 26, pi. vii.)   And this theory equally agrees with the laws
of coexistence of the lateral nerves as established by an extensive induction of
particular dissections.]
                                  36* 
414           HUNTER ON THE ANIMAL CECONOMY.
, on and get upon the small bones and muscles, which are the bases
 for the under fin, and at last they are lost on that fin.  After having
 got between the organ and the above-mentioned parts they are con-
 stantly sending small nerves into the organs, first into the great
 organ and then into the  small one;  also into the muscles of the fin,
 and at last into the fin itself.  These branches, which are sent into
 the organ as the trunk passes along, are so small  that I could not
 trace their ramifications in the organs.   In this fish, as well as  in
 the torpedo,  the nerves which supply the organ are  much larger
 than those bestowed on  any other part for the purposes of sensation
 and action;  but it appears to me that the organ of the  torpedo is
 supplied with much the largest proportion.  If all the nerves which
 go to it were united  together  they would  make a  vastly  greater
 chord than all those which go to the  organ  of this eel.   Perhaps
 when experiments have  been made  upon this fish, equally accurate
 with those made upon  the torpedo, the  reason for this difference
 may be assigned.
                          Blood- Vessels.
    How far this organ is vascular I  cannot positively determine,  but
 from the quantities of small arteries going  to  it I  am  inclined  to
 believe  that it is not deficient in vessels.  The arteries  arise from
 the large artery which passes down the spine ; they go off in small
 branches like the intercostals in the human subject, pass  round  the
 air-bladder, and get upon the  partition  together with  the  nerves,
 and distribute their branches in the same manner.  The veins take
 the  same course backwards, and enter  the  large  vein  which runs
 parallel with the artery.
  [A vivid and interesting account of the mode of capture of the gymnotus,
and the power of its  electric shocks,  is  given  by Humboldt in his Ob-
servalions de Zoologie  et eVAnatomie Comparee, vol. i., p.  49.   An
abstract of these observations will be found in the Cyclopaedia of  Anatomy
and Physiology, art.  ' Animal Electricity,' from  which, towards com-
pleting the view of this interesting subject, we quote the following descrip-
tion of the electrical organs in the Silurus or Malapterurus electricus, a
fish inhabiting the rivers Nile and  Niger.

              " The Electrical Organs in the Silurus.
  " The only organ that can be regarded  as connected with the  electrical
function in this fish is a thick layer of  dense cellular tissue, which com-
pletely surrounds  the body  immediately  beneath the integuments.  So
compact is it that at first sight it might be mistaken for a deposit of fatty
matter.   But under the microscope it appears  to  be  composed of ten-
dinous fibres, closely  interwoven, the meshes of which are filled with a
gelatinous substance.
  " This  organ is divided by a strong aponeurotic membrane into two
circular layers, one outer lying immediately beneath the corion, the other
internal, placed above the  muscles. 
OBSERVATIONS ON BEES.
415
  " Both organs are isolated from the surrounding parts by a dense fascia,
excepting where the nerves and blood-vessels enter.   The cells or meshes
in the outer organ, formed by its reticulated fibres, are rhombic in shape,
and very minute, so as to require a lens to see them well.   The com-
ponent tissue of the inner organ is somewhat flaky, and also cellular.
  " The nerves of the outer organ are branches of the fifth pair, which
runs beneath  the  lateral line, and above the aponeurotic covering of the
organ.   This  aponeurosis is pierced  with  many holes for the transmis-
sion of the nerves, which  are lost within the cellular tissue of the organ.
The intercostals  supply  the inner organ : their electrical  branches are
numerous,  and remarkably fine.   The  organs of the other  known  elec-
trical  fishes have  not  yet come  under the notice of any anatomist.   In
taking a general view of these interesting organs, we are struck with the
existence of a certain degree of analogy amongst them, and yet we fail to
discover  such resemblances as  might be  expected, and such as exist
between the structures  of other organs performing the same functions in
different animals.  Here we have  tendinous membranes variously arranged,
yet all so  as  to form  a series of separate  cells, filled with  a gelatinous
matter.   But how great is the difference between the large columnal cell
in the torpedo, full of delicate partitions, and the minute rhombic cells of
the silurus!
   " All, however, are  equally supplied  with nerves of very great size,
larger than any others in the same animals, and indeed  we may venture
to say, larger than any nerve  in any other animal of like  bulk.  The
organs  vary in different  fishes; first,  in  situation, relatively to other
organs.  They bound  the sides of the head in the torpedo, run along the
tail of the  gymnotus, and  surround the body of  the silurus :  secondly, in
having different sources  of nervous  energy : and thirdly, in the form of
the cells.   No other  fishes have aponeuroses  so extensive, or such an
accumulation  of gelatin and albumen in any cellular organ.  Broussonet
remarked that all the electrical fishes at present known to us, although all
belonging  to  different classes,  have yet certain characters in common.
All, for  instance, have  the  skin smooth, without  scales, thick, and
pierced with small holes, most numerous about  the head, and which pour
out a peculiar fluid.   Their fins  are  formed of soft and flexible  rays,
united by means  of dense membranes.  Neither the gymnotus  nor tor-
 pedo has any dorsal fin ;  the  silurus has only  a small one without rays,
situated  near  the tail.  All have small eyes."]
                 OBSERVATIONS ON PEES.*

                      BY JOHN HUNTER, F.R.S.

                        Of the Conmon Bee.

  The common bee, from a number of peculiarities in its ceconomy,
has called  forth the  attention of the  curious, and from  the profit
arisino- from its labours, it has become the object of the interested ;
therefore no wonder it has  excited universal  attention, even from
  * [This paper was read before the Royal Society, February 23, 1792, and pub-
lished in the 82d volume of the Philosophical Transactions.] 
416
HUNTER ON THE ANIMAL CECONOMY.
the savage to the most  civilized people; but it has hardly been
considered by the anatomist, at least the two modes of investiga-
tion have not gone so  much hand  in hand  as they ought to have
done.
  The history of the bee has rather  been considered as a fit subject
for the curious  at large, whence more  has been  conceived than
observed.  Swammerdam, indeed, has rather erred  on the  other
side, having with great  industry been very minute on the particular
structure of the bee.   I shall here observe that it is commonly not
only unnecessary to be minute in our description  of parts in natural
history, but in general  improper.  It is unnecessary when it does
not apply to anything but the thing itself, more especially if it be  of
no consequence ; but  whenever it applies, then it should so far be
treated accurately.  Minutie  beyond what is   essential,  tire the
mind, and render that which should entertain along with instruc-
tion  heavy and  disagreeable ;  the  more so too if the  parts are
small,  where the  sense can only take them in singly, and the mind
can hardly comprehend the whole or apply all the parts combined
to any consequent action.  This has been too much the case with
Swammerdam;  he often  attempted  too much accuracy in his de-
scription of minute thing.*  But the natural history of insects has
not been  sufficiently  understood at  large, so as to throw light on
this subject where there was an analogy, and where without such
analogy, it must appear  in  the bee alone unintelligible, from the
obscurity attending  some parts of their ceconomy; for there  is
hardly  any species  of animals but what  has  some  part of its
oeconomy obscure, and  probably this is  as much  so in this insect
as in any other class of animals we are at one season of the year
almost daily seeing ; yet these parts  of the ceconomy may be evi-
dent in some other species of the same tribe or genus,  and thus be
cleared up, from  analogy, so that the species assist  each  other  in
their demonstration.  This is evident in  the whole tribe of flying
insects, for what  is lost  or cannot be made out   in the one may be
demonstrated  in another ; and we find there are  some things in the
oeconomy of the  bee that cannot  be seen  or demonstrated in it
alone,  but which  are evident in  some other insects ; and while they
possess the same parts, and other  circumstances are similar, we
must conclude the uses of those parls are similar in both ; for when-
ever a circumstance in one  animal  cannot  be   found  out  in that
animal, but can  in another,  then the natural conclusion is that the
uses are similar in both.
  Though the bee may  be classed in  some degree  among the
  * [If  the objects of the comparative anatomist were limited to the elucidation
of,the function of the organs he dissected, there might then, perhaps, be some
reason in the animadversions in the text; but his researches have a still higher
aim, viz., to trace the general plan which pervades the construction of animals
amidst the various modifications to which each  organ is subject in reference to
particular functions ; and the study of organic homologies requires that attention
be paid to the minutest particulars, independently of considerations as to the uses
in the oeconomy to which they may be subservient.] 
OBSERVATIONS ON BEES.
417
domestic animals, yet from there being such a cluster of them, and
because they are an offensive and irritable animal, their actions are
rendered very obscure, and can only be observed by little starts;
often we can only see the effects, which renders the knowledge of
their oeconomy still imperfect:  they would in many cases seem to
evade our wishes;  they often remove out of our sight part of their
oeconomy when they can.  Thus they often remove their eggs and
young.   Many quadrupeds do this, as cats, &c, and I have reason
to believe that birds can  remove their eggs, at  least I have reason
to suspect the sparrow of this.
   As the bee is an insect, it has most things  peculiar to that class
of animals : such as are  common are not  to be taken notice of in
the history of this insect, but only its peculiarities which distinguish
it from all others, and constitute it  to be a bee  ; and as bees form
a large tribe of insects, it is the  more singular peculiarities that con-
stitute a distinct species of this tribe.  As most parts of the oeconomy
of insects have not been in every respect understood, and although
now known in some insects yet cannot be observed in the bee, but
which accord with many circumstances attending this insect, there-
fore such  must be brought into the present history of the bee to
render it more complete.   I shall not be minute in the anatomy of
this animal, as that would be too tedious and  uninteresting.   When
we talk  of the oeconomy  of the colony, such as the secreting wax,
making  combs,  collecting farina,  honey, feeding  the  maggots,
covering in the chrysalis  and the  honey, stinging, &c, it is  the
labouring bees that are meant.
   In pursuing any  subject most things come to light as it were by
accident, that is, "many things arise  out of investigation that were
not at first conceived, and even misfortunes in experiments have
brought things to our knowledge that were not and probably could
not have  been previously conceived:  on the  other hand, I have
often devised experiments by  the fire-side or in my carriage, and
have also conceived the result; but when I tried the experiment
the result was different, or I found that the  experiment could not be
 attended with all the circumstances that were suggested.
   As bees, from their numbers, hide very  much their operations, it
 is necessary to have  such  contrivances as   will  explore their
 oeconomy.  "Hives with  glass lights in them often show some of
 their operations, and when wholly of glass still more; but as they
 form such a cluster, and  begin their comb in  the centre, little  can
 be seen  till their work becomes enlarged, and by that  time they
 have produced a much larger quantity of bees, so as still to obscure
 their progress.   Very thin glass hives are the best calculated for
 exposing their operations;  the  distance  from side  to side about
 three inches ;  of a height and  length sufficient  for a swarm of bees
 to complete one  summer's work in.  As  one  perpendicular comb,
 the whole length  and height of the hive,  in the centre, dividing it
 into two, is the best position  for exposing  their  operations; it is
  necessary to give  them  a lead or direction to form it so;  therefore 
418          HUNTER ON THE ANIMAL CECONOMY.
it is proper to make a ridge  along  the top from end to end, in the
centre, between  the  two sides, for they  like to  begin their comb
from  an eminence;  if we  wished to have them  transverse or
oblique, it would only be necessary to make  transverse or oblique
ridges in the hive.  I had one made of two broad pieces of plate-
glass, with glass ends, which answered  for simple exposure  very
well; but I often saw  operations going on when I wished to have
caught  some of the bees, or to take out a piece of comb, &c.;
therefore I had  hives made  of the same shape and size, but  with
different panes of glass, each pane  opening with hinges, so that it I
saw anything going on that I wished to examine  more minutely or
immediately, 1 opened  the pane at this part and executed what I
wished as much  as was in my power;  this I was obliged to do with
great caution, as often the comb  was fastened to the glass at this
part.   When I saw some operations going on, the dates or periods
of which I wished to ascertain, such as the time of laying eggs, of
hatching, &c, I  made  a little dot with white paint opposite to the
cell where the egg was laid  and put down the date.
  From these animals forming colonies, and from a vast variety
of effects being produced, and with a degree of attention and nicety
that seem even to vie with man, man, not  being in the least jealous,
has wished to bestow on them more than they possess, viz., a rea-
soning faculty;  while  every action is only instinctive; arid what
they cannot avoid or alter except  from necessity, not from fancy.
They have been  supposed to be legislators, even  mathematicians;
indeed,  upon a superficial  view there  is  some show of reason for
such  suppositions; but people  have gone much further, and  have
filled  up from their imagination every blank, but in so unnatural a
way  that one reads it as if it were the  description of a monster.
Probably the best way of treating the history of this insect is only
to describe what is, and the  reader will immediately see where
authors have been inventing;  however,  there are some assertions
that should be particularly taken  notice of, such as forming queen
bees at pleasure.
  Countries that have but little  variety in their seasons may  have
insects whose oeconomy  is  well adapted to this uniformity, and
which would not be suited to a climate whose seasons are very dif-
ferent ; for insects of countries, whose seasons are strongly  marked,
as in  this, have  a period in their life which it is little in our power
to investigate, and can  scarcely be discovered but by accident, for
experiments often give  little assistance; therefore we are obliged to
fill up this blank  by  reasoning, and  from  analogy, where we  have
any.  This period is  principally the winter, in those insects which
live through that season.  Animals of season are somewhat like
most vegetables,  while  the common bee  is only  an animal of sea-
sons in the common actions of life, or what may be called its volun-
tary actions, and therefore it  is somewhat like the human species,
suited to every country, which may be the reason why it is so uni-
versally an animal, fori believe bees are one of the most universal 
OBSERVATIONS ON BEES.
419
animals known ;* yet this may arise from cultivation, in consequence
of which they have been brought into climates where of themselves
they would not have come.f
   Insects are so small and  so  few of them  are capable of being
domesticated, that the duration of their life is not easily ascertained;
therefore we are  to rely more  on circumstantial than  on positive
or demonstrative proof, and perhaps the life of the common bee may
be least in our power to know, for their  numbers in the same so-
ciety make it almost impossible to be ascertained.  From their form-
ing a colony  or  society, which  keeps stationary, the continuance
of this society is known, but to what age the individual lives is not
known ; we are certain, however, that it is only the labourers and
queens that continue the society, for  the  males  die  the same year
they are formed.   From their fixing on the branches of trees, under
projecting exposed surfaces, when they  swarm, we should be in-
clined to suppose that  they were animals ofa warm climate; yet
their providing liberally for the change of climate, or rather for a
change of season, would, on the  contrary, make us believe they
were adapted for. changeable climates, or rather these two circum-
stances should make us suppose they were fitted for both, and their
universality proves it.   And I do conceive that in a pretty uniform
warm climate their ceconomy may be somewhat different from what
it is in the changeable, as they would not be under the same neces-
sity to lay up so  much store, and probably might employ their cells-
inbreeding, for a much  longer  period;  however, a good  climate
agrees with them best, as also  a good season in an indifferent cli-
mate, such as Britain.  We find the  common bee in Europe, Asia,
Africa, and  America.   That they  may  be, or should be, in the
three first is easily supposed, but how they came to America is not
so readily conceived;  for although  a kind of  manageable  animal,
yet  they do not like such  long confinement  in their hives as would
carry them to the West Indies, excepting in an ice-house ; for when
I have endeavoured to confine  them in their hives they have been   ,
so restless as to  destroy themselves.
   The female and the working bee, I believe in every species, have
stings, which renders them an animal of offence, indeed, but rather
of defence; for although they make an attack, I believe it is by way
of defence, excepting  when they attack one another, which is sel-
dom or never with their stings.   As this belongs more to the labour-
ers, it shall be considered when I treat of them in particular.  Of
 the  whole bee tribe, the common bee is the easiest irritated ; for as

   * [The humble bee was found by Captain Parry in Melville Island, Arctic
 circl6»l
   X  [The true honey bee (Apis mellifica) was originally limited in its geographical
 range to the old world, whence it has been transported to America and other colo-
 nies, where it is now acclimated. The distinguished entomologist Latreille, on
 whose authority we state this fact, finds that the hive bee of the south and east
 of Europe and that  of Egypt differ specifically from the Apis mellifica of the west
 of Europe.] 
420          HUNTER ON  THE  ANIMAL CECONOMY.
they have properly, they are jealous of it, and seem to defend it;
but when not near it they are  quiet, and must be hurt before they
will sting; with all this disposition for defence, which is only to se-
cure their property or themselves, when more closely attacked, yet
they have no covetousness, nor  a disposition to obstruct others.
Thus two bees or more will be sucking  at the same flower, with-
out the first possessor claiming it as his right; a hundred may be
about the same drop of honey, if it is beyond the boundaries of their
own right; but what they have collected they defend.  It is easily
known when they mean to  sting ;  they fly about the object of their
anger  very quickly, and by the quickness of their  motion evade
being struck or  attacked;  which is discovered by the sound of
their wings, as if going to give a stroke as they fly, a very different
noise from that of the wings when  coming home of a fine evening
loaded with farina or honey ; it is then a  soft, contented noise.
When a single bee is attacked by several others, it  seems the most
passive animal possible, making no  resistance, and even hardly
seeming to wish to get away; and in this manner they allow them-
selves to be killed.  They are perhaps the only insect that feeds in
the winter, and therefore the only one that lays up external store;
and as all animals, whether insects  or  not, that keep quiet in the
winter, without either eating at all,  or eating very  little in propor-
tion  to what they do in  the  summer, grow fat and muscular in the
summer (which I term internal store), we see why the common bee
need  not be fatter at  one time than another; and accordingly we
find them nearly of the same fatness the year round.
   There are accidents befalling hives of bees that are not easily ac-
counted for.  I had a hive, which in the month of November was
become quite empty of  bees, and upon examination had no honey
in it,  which was strong in the summer, and  had  violent attacks
made upon it in October by wasps  belonging to a nest in the  gar-
den,  but appeared  quiet when  that  nest was  removed.  Upon
examining this hive,  I found only five dead bees, and not a drop of
honey in any one cell:  there  was a good deal of bee bread in dif-
ferent cells scattered up and down  the comb, which was become
white  with  mould on its surface.  On the other hand, I  have  had
swarms die in the winter in the hives, while there was great plenty
of honey in the combs;  what seemed remarkable, they all died  with
their proboscides elongated, and in those which I opened, I found
the  stomachs full of honey, and their intestines full also of excre-
ment, especially the  last part.

                     Of the  Heat  of Bees.
   Bees are perhaps the only insects that produces heat within itself,*

   * [It has been long known that other social insects besides the bee maintain,
when congregated in their  habitations, a  higher temperature than  that of the
external atrnosphere.  In an excellent and  highly important series of experi-
ments on  this subject recently communicated by Mr. Newport to the Roval
Society, it is shown that insects in general have the power of generating animal 
OBSERVATIONS ON BEES.
421
 and were  therefore intended  to  have a  tolerably well-regulated
 warmth, without which, of course, they  are  very uncomfortable
 and soon  die;  and which  makes  not only a part  of their internal
 oeconomy respecting the individual, but a part of their external  or
 common oeconomy, and is  therefore necessary to be known.   The
 heat  of bees is  ascertainable by the thermometer, and I shall  give
 you the result of experiments made at two different seasons of the
 year.
   July 18th, at ten in the evening,  wind northerly, thermometer at
 54° in the open  air, I introduced it into the top ofa hive full of bees,
 and in less than five minutes it  rose to 82°.   I let it stand all night;
 at  five in the morning it was down  at 79°; at nine  in  the same
 morning it  had  risen  to 83°, and at  one o'clock to 84°; and at  nine
 in the evening it was down to 78°.
   December 30th, air at 35°, bees at 73°.
   Although bees support a heat nearly equal to that of a quadruped,
 yet their external covering is not different from that of insects which
 do not;  there is no difference between their coat and common fly's
 or wasp's, nor are they fatter, all which makes them bad retainers
 of heat; therefore they are chilly, and  in a cold too severe for them
 to be comfortable in, they make up for their want of size singly and
 get into clusters.  A single bee has so little power  of keeping itself
 warm, that it presently becomes numbed, and almost motionless: a
 common night in summer will produce this effect.  A  cold capable
 of producing such effects kills them  soon, by which means vast num-
 bers die ;  therefore a common  bee  is obliged  to feed and live  in
 society to keep  itself warm in cold weather.
   We know that the consumption of heat may be greater than the
 power of forming it; when that is the case we become sensible  of
 it, and then take on such actions as are either instinctive, such as arise
 naturally out of the impression, or  as  reason, custom, or habit di-
 rect.   Many animals upon the impression of cold,  coil themselves
 up in their own fur, bringing all their extremities into the centre or
 hollow  of the belly;  birds  bring their feet under the  belly,  and
 thrust  their bill  between their wing and body; many  if not all, go
 to the  warmest places, either from instinctive  principle or habit;
 but the bees have no other mode but forming clusters, and the larger

 heat; that that power in the solitary insects is greatest in the diurnal species of
 flying insects, especially  such as reside most constantly in the open air.   The
law that the mature or more perfect animal is " more capable  of generating heat
than when it is younger"  (see p. 159), is well exemplified by Mr. Newport in
the class of insects.
  In the Lepidoptera, the average elevation of the temperature of the body above
that of its' surrounding medium is in the larvae from  0°.9, to  1°.5, while  in
the imago it is from 5° to 10°.  Among the Hymenoptera it  is from 2° to 4° in
the larva, and in the imago  from  4° to 15°, or even 20°.   In  all these cases the
amount of animal heat developed is in the ratio of the consumption of oxygen
and the quantity of carbonic acid formed in the change of the arterial into serous
 blood ; or in other  words, in proportion to the energy with which the functions
of respiration and locomotion go on in the insect.]
                                37 
422          HUNTER ON THE ANIMAL CECONOMY.
the better.   As they are easily affected by  cold, their  instinctive
principle respecting cold is very strong, as likewise with regard to
wet.  I have seen a swarm hanging out at the door of a hive ready
to take flight, and then return;  a chill has come on  of which I was
not sensible, and in a few minutes the whole has gone back into the
hive;  and by the cold increasing, I have at  length perceived the
cause of their return.  If rain  is coming on, we observe  them re-
turning  home  in great  quantities, and  hardly any abroad.  The
eggs of bees require this heat as much as themselves, nor  will the
maggot live in a cold of 60° or 70°, nor even their chrysalis.  This
warmth keeps the wax so soft as to allow them  to model it with
ease.   In glass hives, or those that have windows of glass  in them,
we often find a dew on the inside of the glass, especially when the
glass  is colder than the air within ;  whether this is perspiration
from the bees, both from their  external surface and lungs, or eva-
poration from the honey,  I cannot say.
   Bees  are very cleanly animals respecting themselves, although
not so respecting  the remains  of their young.   They, I  believe,
seldom or  never evacuate  their excrement  in the hive.   I  have
known them confined many days without discharging the  contents
of the rectum, and  the moment  they got abroad  they evacuated in
the air when flying; and  they appear to be very nice in their bodies,
for I have often detected them cleaning one another, more especially
if by accident  they are besmeared with honey.
   This animal may be considered alone, or so far  as  concerns its
own oeconomy as  an individual, which is  common  to the  most
solitary animals; but it can also be  considered  as a member of
society, in which it is taking an active part, and in which it  becomes
an object of great curiosity.
   To consider this society individually, it maybe said to consist of
a female breeder, female  non-breeders, and males;  but to  consider
it  as a community, it may be said to consist only of female  breeders
and non-breeders,  the  males answering no  other purpose  than
simply as a male, and are only temporary;  and  it is probable the
female breeder is to be considered in no other light than as a layer
of eggs, and that she only influences the non-breeders  by  her pre-
sence, being only a bond of union, for without  her they  seem to
have no tie; it is  her  presence that  makes them an aggregate
animal.  May we not suppose that the offspring of  the queen have
an attachment to the mother, somewhat similar to  the attachment
of young birds to the female that brings them up ?  for although the
times of their attachment are not equal, yet it is  the  dependence
which each has on its mother that constitutes the  bond ;  for bees
have none without  her:  however, the  similarity  is not exact, for
young animals who have lost their nurse will "herd together, and
jointly make the best shifts they can, because in future They are to
become single animals; but bees have an eternal instinctive*depend-
ence on the mother, probably from  there not being distinct sexes.
When the queen is lost, this attachment is broke; they give up in- 
OBSERVATIONS ON BEES.
423
dustry, probably die, or we may suppose, join some other hive.
This is not the  case with  those of this  tribe whose  queen singly
forms a colony; for although the queen is destroyed, yet they go on
with that work which is their lot, as the wasp, hornet, and humble
bee.  Most probably the whole oeconomy of the bee,  which we so
much admire, belongs to the non-breeders, and depends on their
instinctive powers being set to work by the presence of the breeders,
that being their only enjoyment; therefore when we talk of the
wonderful ceconomy of bees, it is chiefly the labourers at large we
are to admire, although  the queen gets the principal  credit for the
extent of their instinctive properties.
  This oeconomy, in its appearances and  operations, is somewhat
similar to human society, but very different in its first causes and
mode of conduct.   The human species sets up its own  standard;
the bee has one set up by nature, and therefore fulfils all the neces-
sary purposes.  This standard of influence, which is the breeder, is
called the queen, and I shall keep to the  name, although I do not
allow her voluntary influence or power.
  The non-breeders are what compose the hive, or what  may be
called the community at large; and  the  males are  mere males:
each of these parts of the community I  shall hereafter consider
separately.
  To take  up the common bee in any  one period of the year, or in
other words,  in any one month, and carry it round to the same, and
observe what happens in that time, is probably including the whole
ceconomy of  bees ;  for although they may live more than one year,
which I believe is not  known, from its not being easily ascertained,
yet each year can only be a repetition of the last, as I conceive they
are complete  in the first; therefore the history of one  year may be
said to make  a  whole, and of course it is not material at what time
in the circle we begin the history.
  Perhaps  the best time to begin the history of  such insects as
only come  to full growth the season  they are bred, and live through
the winter, and breed  the summer following, is when  they emerge
from the torpid state, and begin to breed;  but it might be thought
that the common bee is an exception to this rule, because they begin
early in the spring to breed, generally  before they can be observed ;
and as they breed to form  a colony,  which is to go off from the old
stock, in order to set out anew, it might seem most natural to begin
with this colony, and trace it through  its  various actions of life  for
one year, when it as it were regenerates itself, and comes round to
the same point again  that the old stock was in when  it threw off
this colony.
  Bees, like every other animal that is taken care  of in the time of
breeding or incubation, and nursed to the  age  of taking  care of
itself, cannot  be said to have a period in  which we  can begin its
natural history; but in some other insects there is such  a period,
for  they can  be traced from an egg, becoming totally independent
of the parent from the moment of being laid, as the silk-worm, &c. 
424          HUNTER ON THE ANIMAL CECONOMY.
There are three periods at which the history of the bee may com-
mence: first, in the spring, when the queen begins to lay her eggs;
in the summer, at the commencement of a new colony; or in the
autumn, when they are going into winter-quarters.   I shall begin
the particular history of the bee with the new colony, when nothing
is formed ;  for it then  begins everything that can possibly happen
afterwards.
  When a hive sends off a colony it is commonly in  the month of
June; but that will vary according to the  season, for in a  mild
spring bees sometimes swarm in the middle of May, and very often
at the latter end of it.  Before they come off they commonly hang
about the mouth of the hole or door  of the hive for some days, as
if they  had  not sufficient room  within for such hot  weather, which
I believe is  very much the case ;  for if cold  or wet weather come
on, they stow themselves very well,  and  wait for fine  weather.
But swarming appears to  be  rather  an operation  arising from
necessity, for they would  seem not naturally to swarm, because if
they have an empty space to fill, they do not swarm ; therefore by
increasing the size of the  hive, the swarming is prevented.   This
period is much longer in some than in others.  For some evenings
before they come off, is often heard a singular noise, a kind of ring, or
sound ofa small trumpet;  by comparing it with the notes of the piano-
forte, it seemed to be the same sound with the lower A of the treble.
  The  swarm commonly consists  of three classes; a female, or
females,* males, and those commonly called mules, which are sup-
posed to be of no sex, and are the labourers; the whole about two
quarts in bulk, making about six or seven thousand.   It is a question
that cannot easily be determined, whether this old stock sends off
entirely young of the  same season, and whether the whole of their
young  ones, or  only part.  As the males are entirely bred in the
same season, part  go off; but part must stay, and most  probably
it is so  with the others. They  commonly come off in the heat of
the day, often immediately after a shower; who takes the lead I do
not know, but should  suppose it was the queen.  When  one  goes
off they all  immediately follow, and  fly  about seemingly in great
confusion, although there is one principle  actuating  the  whole.
They soon appear to be directed to some fixed  place, such as the
branch ofa tree or bush,  the cavities  of old trees, holes of houses
leading into some hollow  place; and whenever the stand  is made,
they all immediately repair to it, till they are all collected.  But it
would seem in some cases that they had  not fixed upon any resting
place before  they  came off, or if they  had, that they were either
disturbed, if it was near, or that  it was at a great distance; for  after
hovering some time, as if undetermined, they fly away, mount up
into the air, and go off with great velocity.   When  they have fixed
upon their  future  habitation, they immediately begin  to make  their
combs,  for they have the  materials within themselves.  I  have
  * I have reason to  believe that never more than one female comes off with a
swarm. 
OBSERVATIONS ON BEES.
425
reason to believe that they fill their crops with honey when  they
come away ; probably from the stock in the hive.   I killed several
of those  that  came  away,  and  found their  crops   full, while
those that remained in the hive had their  crops not near so  full:
some of them came  away with  farina on their legs, which I con-
ceive to be rather accidental.   I may just observe here, that a hive
commonly sends  off two, sometimes  three swarms in a summer;
but that the  second is commonly less than the first, and the third
less than the second ; and this last has  seldom time to provide for
the winter :  they shall often threaten to swarm, but do not; whether
the threatening is  owing to too many bees, and their not swarming
is owing  to there  being no queen,  I do not  know.  It sometimes
happens that the swarm shall  go back again;  but in such instances
I have reason to think  that they have lost their queen,  for the hives
to which their swarm have come back do not swarm the next warm
day, but shall hang out for a fortnight or more,  and  then swarm;
and when they do, the swarm is commonly much  larger than be-
fore,  which makes me suspect that  they waited  for the queen that
was  to have gone  off with the next  swarm.
   So far we  have  set the colony in  motion.  The materials of their
dwelling, or comb, which is the wax, is  the next consideration, with
the mode of forming, preparing, or  disposing of it.   In giving a to-
tally  new account of the wax, I shall first show it can hardly be
what it has  been supposed to be.   First I shall observe that the
materials, as they are found  composing the  comb, are not to be
found in the same state (as a composition) in any vegetable, where
they have been supposed to be got.  The substance brought in on
their legs, which is the farina of the flowers of plants, is, in common,
I believe, imagined to be the materials of which the wax is made,
for it is called by most the wax :  but it is the farina, for it is always
of the same colour as the farina of the flower where they are gather-
ing;  and indeed we see them  gathering it, and  we also see  them
covered almost all  over with it, like  a dust; nevertheless, it has
been  supposed to be the wax,  or that the wax  was extracted  from
it.  Reaumur is of this  opinion.   I made several experiments to see
if there was  such a quantity of oil  in it as would  account for the
quantity of wax to be formed, and  to learn if  it  was composed of
oil.   I held it near the candle; it burnt, but did not smell like wax,
and had the same  smell when  burning, as farina when it was burnt.
I observed that this substance was  of different colours on different
bees, but always of the  same  colour on  both legs of the  same bee ;*

  * [Aristotle, who describes many interesting particulars of the oeconomy of
the bee, and knew something of the structure of the interior of the hive, was the
first to observe that a bee in each single excursion from the hive always visits
the same species of flower, and consequently comes home laden with pollen of
the same colour.  This has been confirmed by all subsequent observers, and, as
we see, did not escape Mr. Hunter.  The necessity for this instinct arises out
of the operation which the pollen first undergoes ;  the bee rakes  out the pollen
with incredible quickness by means of its  first pair of legs, then passes it to the
middle pair, which transfer it to the hind legs, by which it  is wrought up into
                              37* 
426          HUNTER ON THE ANIMAL CECONOMY.
whereas new-made  comb was all of one colour.   I observed that
it was gathered with more  avidity for old hives, where the  comb
is complete, than for those hives  where it is only begun, which we
*-ould hardly conceive if it was the materials of wax: also we may
observe that at the very beginning ofa hive, the bees seldom bring
in any substance on their legs for two or three days, and after that
the farina gatherers begin to increase; for now some cells are
formed to hold it as a store, and  some eggs are  laid, which  when
hatched will require this substance as food, and which will be ready
when the weather  is wet.  I have  also  observed, that  when the
weather has either been so cold,  or so wet, in June, as to hinder a
young swarm from  going abroad, they have yet in that time formed
as much new comb as they did in the same time when the weather
was such as allowed them to go  abroad.   I have seen them bring
it in about the latter end of  March, and  have observed in  glass
hives the bees with the farina on their legs, and have seen them dis-
posing of it, as will be described hereafter.
   The wax is formed by the  bees themselves ; it may be called an
external secretion of oil,  and I   have found  that  it is  formed be-
tween each scale of the under side of the belly.*   When I first ob-
served this substance, in my examination of the working bee, I was
at a loss to say what it was: I   asked  myself if it was new scales
forming, and whether they cast the old, as the lobster, &c, does'?
But it was to be found  only between the scales, on the lower side
of the belly.  On examining the bees through glass hives while they
were climbing up the glass I  could  see that most of them had this
substance, for it  looked as if  the lower or  posterior edge   of the
scale was double, or that there were double scales; but I perceived
it was loose, not attached.   Finding that the substance brought in
on their legs was farina, intended, as appeared from every circum-
stance, to be the food of the maggot, and  not to make wax, and not
having yet  perceived anything  that could  give  me the least idea
of wax, I conceived these  scales might  be  it, at  least  I thought it
necessary to  investigate them.   I therefore took several  on  the
 point ofa needle, and  held them  to a candle, where they  melted,
and immediately formed themselves into a round globe ; upon which
I no longer doubted but this was the wax, which opinion was con-

 little pellets.  Now if the pollen were taken  indiscriminately from  different
 flowers, the difference  in the size and  shape of the pollen-grains would  probably
 prevent them cohering  together  sufficiently to  allow of the pellet being formed.
 Hence it is that in watching the return of bees to the hive some may be seen
 laden with yellow-coloured pellets, others with orange, pink, white, or  greenish-
 coloured ones. The grains of pollen are not changed by the operation of kneading
 when  detached from the pellet; under a miscroscope they are seen to possess
 their original  figure.]
   * [Hunter first confirmed this statement by actual observation, but  the merit
 of the discovery is entirely Hunter's.  The only approach to it is in the observa-
 tion by Morley, who says that  he has taken bees with six pieces of wax within
 the plaits of the abdomen, three on each side (Female Monarchy, 1774),  but with-
 out knowing the source of these pieces of wax.] 
OBSERVATIONS ON BEES.
427
firmed to me by not finding those scales but in the building season.
In the bottom of the hive we  see a good many of the scales lying
loose,  some pretty perfect, others in pieces.  I have endeavoured
to catch them, either taking this matter out of themselves, from be-
tween the scales of the abdomen, or from one  another, but never
could satisfy myself in this respect: however I once caught a bee
examining between the scales of the belly of another, but I could
not find that it took anything from  between.   We very often see
some of the bees  wagging  their belly, as if tickled, running round
and to and fro for only a little  way, followed by one or two other
bees, as if examining them.  I conceived they were probably shak-
ing out the scales of wax, and that the  others  were ready upon
the watch to catch them, but I could not absolutely determine what
they did.  It is with these scales that they form the cells called the
comb, but perhaps not entirely, for I believe they mix farina with
it; however, this  only occasionally,  when probably the secretion is
not in great plenty.  I have some reason to think that where no
other substance is introduced the thickness of the scale is the same
with that  of the sides of the comb;  if so, then  a comb may be no
more than a number of  these united ; but a great deal of the comb
seems to be too thick for this, and, indeed, would appear to be a
mixture similar to the covering  of the chrysalis.  The wax natu-
rally is white, but when melted from the comb at large it is yellow.
I apprehended this might arise from its being  stained with honey,
the excrement of the  maggots, and with the bee-bread.  I steeped
some white comb  in honey, boiled  some with farina as also with
old comb, but I could not say that it was  made yellower.  Wax, by
bleaching, is  brought back to  its  natural  colour, which is also a
proof that its colour is derived  from some mixture.   I have reason
to believe that they take the  old  comb, when either broken down,
or by any accident rendered  useless, and employ it again; but this
can only  be with  combs  that  have  had no bees hatched in them,
for the wax cannot be separated  from the silk afterwards.   Reau-
mur supposed that they new  worked up the old materials, because
he found  the covering of the chrysalis of a yellower colour than  the
other parts of the new comb; but this is always so, whether they
have old  yellow comb to work up or not, as will be shown.
   The bees who gather the farina also form the wax, for I found it
 between their scales.
   The cells, or rather the  congeries of  cells, which compose  the
 comb, may be said to form perpendicular plates or partitions, which
 extend from top  to bottom of the cavity in which they build them,
 and from side to side.  They always begin at the top or roof of the
 vault in which  they build, and  work downwards; but if the upper
 part of this vault, to which their combs are fixed, is removed, and
 a dome is put over, they begin at the upper edge of the old comb
 and work up into the new cavity at the  top.  They generally may
 be guided as to the direction of their new plates  of comb, by form-
 ing ridges at top, to which they begin to attach their comb.  In a 
428
HUNTER ON THE ANIMAL CECONOMY.
long hive, if these ridges are longitudinal, their plates of comb will
be longitudinal;  if placed transverse, so will be the  plates ;  and if
oblique, the plates of comb will be oblique.  Each plate consists  of
a double  set of cells, whose bottoms form the  partition between
each set.  The plates themselves are not very regularly  arranged,
not forming a regular plane where they might have done so; but
are often adapted to the situation or shape of the cavity in which
they are built.  The bees do not endeavour to shape their cavity to
their work, as the  wasps do, nor are the cells of equal depths, also
fitting them  to their situation; but as the breeding cells must all  be
of a given depth, they  reserve a sufficient number for breeding  in,
and they put the honey into the others, as also into the shallow ones.
The attachment  of the comb round the cavity is not continued, but
interrupted so as to form passages;  there  are also passages in the
middle of the plates, especially if there be a cross stick to  support
the comb; these allow  of bees  to go across from plate to  plate.
The substance which they  use for  attaching  their  combs to sur-
rounding parts is not the same as the common wax ; it is softer and
tougher, a good  deal like the substance with which  they cover  in
their chrysalis or the humble bee surrounds her  eggs.   It is pro-
bably a mixture  of wax with farina.   The cells are placed  nearly
horizontally, but not exactly so; the  mouth raised  a  little, which
probably may be to retain the honey the better;  however, this rule
is not strictly observed, for often they are horizontal, and towards
the lower edge ofa plane of comb they are often declining.   The
first combs that  a hive forms are the smallest, and much neater than
the last or lowermost.  Their sides or partitions  between cell and
cell are much thinner, and the hexagon is much more perfect.   The
wax  is purer, being probably little else  but wax, and it is more
brittle.  The lower combs are considerably larger, and  contain
much more  wax, or perhaps, more properly, more materials; and
the cells are at such distances as to allow  them  to  be of a round
figure : the wax is softer, and there is something mixed with it.   I
have observed that the cells are not all of equal size, some  being a
degree larger than the  others; and  that the small  are the first
formed, and of course  at the upper part where the bees begin, and
the larger are nearer the lower part  of the comb, or last  made:
however,  in hives  of particular construction, where  the  bees  may
begin to work at one end, and can work both down and towards
the other  end, we  often find the larger cells both  on the lower part
of the combs and also at the opposite end.
   These  are formed for the males  to be bred in; and  in the
hornets' and wasps' combs  there are larger cells  for the queens  to
be bred in: these are also formed  in  the lower tier, and  the last
formed.
   The first comb made in a hive is  all of one colour, viz., almost
white; but it is  not so  white towards the end of the season, bavin*
then more of a yellow  cast. 
OBSERVATIONS ON BEES.
429
                       Of the Royal Cell.
  There is a cell which is called the royal cell, often three  or four
of them, sometimes more; I  have seen eleven, and even thirteen in
the same hive;  commonly they are placed on the  edge of one or
more of the combs, but often on the side of a comb; however, not
in the centre along with the  other  cells, like  a large one placed
among the others, but often against  the mouths of the cells, and
projecting out beyond the common surface of  the comb; but most
of them are formed from the edge of the comb, which  terminates
in one of these cells.   The royal  cell is  much wider than the others,
but seldom so deep: its  mouth  is  round, and appears to be the
largest half of an oval in depth, and is declining downwards, instead
of being horizontal or lateral.  The materials of which  it is com-
posed are softer than common  wax, rather like the last mentioned,
or those of which ihe lower edge of the plate of comb is made, or
with which the bees cover the chrysalis: they  have very little
wax in  their composition, not one-third; the rest I conceive to be
farina.
  This  is supposed to be the cell in which the queen is  bred, but I
have reason to believe  that this is only  imagination: for, first, it is
too large, and, moreover, seldom so deep as the large cells in which
the  males are  bred; whereas, if proportioned to the length of the
queen, it ought to be  deeper, for  length  of body is her greatest dif-
ference.  In the second place,  its mouth is placed downwards ;  and
in the third place, it  is never lined with the silken covering of the
chrysalis, similar  to  the  cells  of the males and labourers; nor do
we  find excrement at the bottom of it.   The number of these cells
is very  different in different hives.  I think I have seen hives with-
out any, and I have  seen  them with  eleven or twelve, sometimes
more.   I  have  examined  them  at  all  times through the summer,
but never found any alteration in them.
  The  comb seems  at  first to be formed for  propagation, and the
reception of honey to be only a secondary use ; for if the bees lose
their queen they make no combs; and the wasp, hornet, &c, make
combs,  although they collect no honey;  and the humble bee collects
honey,  and deposits it in cells she never made.
  I shall not consider the bee as  an excellent mathematician, capa-
ble  of  making exact forms, and having reasoned  upon the best
shape  of  the cell for capacity,  so  that the greatest  number might
be  put into the smallest space  (for the hornet and the wasp are
much more correct,  although not seemingly under the same neces-
sity, as they collect nothing to occupy their cells);  because, although
the  bee is pretty perfect in  these respects, yet it is very incorrect
in others, in the formation of the comb: nor shall I consider these
animals as forming comb of certain shape and size, from mere me-
chanical necessity, as from working round themselves; for such a
mould  would not form  cells  of different sizes, much less could
wasps be guided by the  same  principle, as their cells are of very 
 430          HUNTER ON THE ANIMAL CECONOMY.

 different sizes, and the first by much too small for the queen wasp
 to have worked round herself:  but I shall consider the whole as an
 instinctive principle, in which the animal has no power of variation
 or  choice, but  such as  arises  from what  may be called external
 necessity.  The cell has  in common six sides, but this is most cor-
 rect in those first formed ;  and  their bottom is commonly composed
 of  those sides  or planes, two of the sides  making one;  and they
 generally fall in between the bottoms of three cells of the opposite
 side; but this  is not regular, it is only to be found where there is
 no  external interruption.
  I have already observed, that the last-formed cells in the season
 are not so well made ; that their partitions are thicker, and more
 ofa yellow colour:  this arises,  I imagine, from the wax being less
 pure, having more  alloy in it;  and therefore,  not  being so  strong,
 more of it is  required.  The bees would appear to  reserve many of
 their cells for honey, and those are mostly at the  upper  part.  In
 old hives, of  several years' standing, I have found the upper part
 of the comb free from the consequences of having bred, such as the
 silk lining, and the excrement of the maggots at the bottom; while
 the lower part, for  probably more than one-half of the plane of
 cells, showed strong marks of having  contained  many broods of
 young bees.  In such the lining of silk is thick at the sides, com-
 posed of many laminae;  and in many,  the bottom  is half filled up
 with  excrement; and I  observed  at  such  parts, the  comb was
 thickest at its mouth, which inclines me to think, that when a cell
 becomes shallow, by the bottom  being in some  degree filled  up, the
 bees then add to its mouth.  Such also  they seem  to reserve prin-
 cipally  for the  bee-bread;  so  that to  lay up  a  greater store of
 honey is an object to them.

                    Of the Laying of Eggs.

  As soon as a few combs are formed, the female bee  begins laying
 of eggs.  As far as  I have  been able to observe, the queen is the
 only bee that propagates, although it is  asserted that  the labourers
 do.   Her first eggs in the season are those which produce labourers;
 then the males, and  probably the queen; this is the progress in the
 wasp, hornet, humble bee, &c.   However, it is asserted by Riem,
 that when a hive is  deprived ofa queen, labourers  lav eggs;  also,
 mat at this time, some honey and farina  are brought in as store for
 a wet day.  The eggs are laid at  the  bottom of the cell, and we
 find them there before the cells  are  half completed, so that  propa-
 gation begins early and  goes on along with the  formation of the
 other cells.   The egg is  attached at one end to the bottom of the
 cell, sometimes standing  perpendicularly, often obliquely; it has a
glutinous or  slimy covering, which makes  it stick to anything it
touches.   It  would  appear  that  there was  a period or periods for
laying eggs;  for I have observed in a  new swarm that the great
business of laying eggs did not last above a fortnight; although the 
OBSERVATIONS ON BEES.
431
hive was not half filled with comb, it began to slacken.  Probably
tnat end of the egg which is  first protruded is that which sticks to
the bottom of the  cell; and probably the tail of the maggot is
formed  at  that end :  when they move the egg, how they make it
stick again, 1 do not know.   I have just observed, that they often
move the  egg out  of a cell to some other, we may suppose ;  why
they do this 1  cannot say ; whether it  is  because  we have  been
exposing this  part,  is not easily determined.  In those new-formed
combs,  as  also in  many not half  finished, we find the substance
called  bee-bread, and some of it is  covered over with wax, which
will be  considered  further.   By the time they have worked above
half way down the hive with the comb, they are beginning to form
the larger  cells,  and by this time  the first broods are hatched,
which  were  small  or labourers;  and  now they begin to breed
males, and  probably a queen, for a new  swarm; because the males
are now bred  to impregnate the young queen for the present  sum-
mer, as also for the next year.   This progress  in  breeding is the
same with  that of the wasp,  hornet, and humble bee.*  Although
this account is commonly allowed, yet writers on this subject have
supposed another mode of producing a queen, when the hive is in
possession of maggots, and deprived of th»ir queen.
  What may be called the complete process of the egg, namely,
from the time of laying to the birth of the bee, (that is, the  time of
hatching,) the  life of the maggot, and the life of the chrysalis, is, I
believe, shorter than in most insects.  It is  not easy to fix the  time
when the eggs hatch ; I have been led to imagine it was in five days.
When they hatch, we find the young maggot lying coiled up in the
bottom  of  the  cell,  in some degree surrounded  with a transparent
fluid.  In many of the cells,where the eggs have just hatched,  we find
the skin standing in  its place, either not yet removed, or  not pressed
down by the maggot.  There is now an additional employment for
the labourers,  namely, the feeding and nursing the young maggots.
We may suppose the queen  has nothing to do  with this, as there
are at all times labourers  enough in the hive for such purposes,
especially loo as she never does bring the materials, as every other
of the tribe is  obliged to do at first; therefore she seems to be a
queen by hereditary, or rather by natural right, while the  humble
bee, wasp, hornet, &c, seem rather to work  themselves into royalty,
or mistresses of the  community.   The  bees  are readily detected
feeding the  young maggot;  and indeed a young maggot might easily
be brought  up by any person who  would  be  attentive to  feed it.
They open  their two lateral  pincers to receive the food, and swallow
it.  As they grow, they cast their coats  or  cuticles; but how often


  * Reaumur  on  Bees  says that the  drone eggs, when laid in small cells,
produce  drones;  and Wilhelmi says that it is the labourers only thai lay drone
eggs. Mr. Riem says  that queens are never  reared in  any but royal cells,
although  males sometimes in common cells; and workers in old queen cells, but
never in those recently made. 
432          HUNTER ON THE ANIMAL CECONOMY.
 they throw their coats, while in the maggot state, I do not know.*
 I observed that they often removed their eggs; I also  find they
 very often shift the maggot into another cell, even when very large.
 The maggots grow larger  and larger till they nearly fill the cell;
 and by this time they require  no  more food, and are ready to be
 inclosed for the  chrysalis state: how this  period is discovered I do
 not know,  for in every other insect, as far as I am  acquainted, it is
 an operation of the maggot or  caterpillar itself;  but in the common
 bee it is an operation of the perfect animal;  probably it arises from
 the maggot refusing food.  The time between their being hatched
 and their being inclosed is, I believe, four  days; at least, from  re-
 peated  observations, it  comes nearly to that time.  When ready
 for the chrysalis state, the  bees cover over the mouth of the cell
 with a substance of a light  brown colour, much in the same man-
 ner that they cover the honey, excepting that in the present instance
 the covering is convex  externally, and  appears not to be entirely
 wax, but a mixture of wax and farina.    The maggot is now per-
 fectly  inclosed,  and it begins  to line the  cell and  covering of the
 mouth  above-mentioned  with  a silk it spins out similar to the silk-
 worm, and which makes a kind of pod for the  chrysalis.  Bonnet
 observed that in  one instance the cell was too short for the  chrysalis,
 and it broke its covering, and formed  its pod higher or more convex
 than common: this I can conceive possible; we often see it in the
 wasp.   Having completed this lining, they cast  off, or rather shove
 off  from the  head backwards, the last maggot  coat, which is de-
 posited at the bottom of the cell, and then they become chrysalises.

 Of the Food of the  Maggot, or  what is commonly called Bee-Bread.

  One   would naturally  suppose  that the food of the maggot bee
 should  be honey, both because it is the food of the old ones, and it
is what they appear principally to collect for themselves ;  however,
the circumstance of honey  being food for  the old ones is  no argu-
 ment, because very few young animals live  on the  same  food with
the old, and therefore it is probable the maggot bee  does not live
upon honey;  and  if we  reason from analogy,  we  shall  be led to
suppose the bee-bread to be the food  of the maggot.   It is the food
of the maggot of the humble bee, who feeds upon honey,  and even
lays up  a store of honey for a wet day, yet does  not feed the young
v/ith it.  It is the food of the maggot of a black bee, and also of
several  others of the solitary kind who also feed  upon honey; and
wasps,  &c, who do not bring  in such materials, do  not feed them-
selves upon honey.   We  cannot suppose  that the  bee-bread is for
 the  food of the  old bees, when we  see  them  collecting it in the
months  of  June  and July, &c... at which time they have  honey in

  * [It has not yet been ascertained  that the larva of the  bee sheds  its skin, as
the lepidopterous caterpillars do, except when on the point of becoming a pupa,
at which period a thin pellicle is also thrown out by each of the stigmata from
the tracheal tubes.] 
OBSERVATIONS ON BEES.
433
great plenty; this substance is as common to a hive as any part be-
longing to the oeconomy of bees.  Before they have formed five or
six  square inches of comb in a young hive, we shall find eggs,
honey, and  bee-bread ; and at whatever time of the year we kill a
hive, we shall find  this substance;  and if a hive is short of honey
and dies in the winter, we find no honey, but  all the bee-bread, which
was laid up in store for the maggots in the spring.  They take great
care of it, for it is often covered over with wax as the honey, and I
believe  more especially in the winter ; probably with a view to pre-
serve it till wanted.   In April I have found some of the cells full,
others only half full.  If we slit down a cell filled with this sub-
stance,  we shall commonly find it composed of layers of different
colours ; some a deep orange, others a pale brown.  In glass hives
we often find that the glass makes one side of the cell, and frequently
in such we shall see at once the different strata  above-mentioned.  This
is the substance which they bring in on their legs, and consists of
the farina of plants.  It is not the farina of every plant that the
bee collects, at least they are found gathering it from some  with
great industry, while we  never  find them  on  others: St. John's
wort is a favourite plant, but that comes late.  The flower of the
gourd, cucumber, &c, they seem to  be fond of.  What  they  do
collect must be the very loose stuff, just ready to be blown off to im-
pregnate the female part of the flower ; and to show that this is the
case, we find bees impregnate flowers that  have not the male part.
It is in  common of a yellow colour, but that of different shades,
often of an orange; and when we see  bees  collecting it on bushes
that have a great many  flowers, so as to furnish a complete  load,
it is then of the colour of the farina of that  bush.  It  is curious to
see them deposite this substance in the cell.   On viewing the hives,
we often see bees with this substance on their legs, moving along
on  the combs, as if looking out for  the cell to deposit it in.  They
will often walk over a cell that has some deposited in it, but shall
'leave that, and try another, and so on till they fix;  which made me
conceive that each bee had its  own cell.  When they come to the
intended cell, they put their two hind legs into it, with the two fore
legs and the trunk out on the mouth of the neighbouring cell, and
then the tail or  belly  is thrust down  into  the intended cell; they
then bring the leg under the belly, and turning the point of the tail
to  the oufside of the  leg, where the farina  is, they shove it off by
the point of the tail.  When it is thus shoved off both  legs, the bee
leaves it, and the two pieces of farina may  be seen lying at the bot-
tom of the cell; another bee comes almost immediately, and creep-
ing into the cell, continues about five minutes, kneading and work-
ing it down into the bottom, or spreads it over what was deposited
there before, leaving  it a smooth  surface.
   It is of a consistency like  paste,  burns slightly, and gives a kind
of  unusual smell, probably from having been mixed with animal
iuice in the act of kneading it  down, for  when brought in it is
rather a powder than a paste.   That  it is the food of the maggot is
                               38 
434           HUNTER ON THE ANIMAL CECONOMY.
proved by examining the animal's  stomach; for when we kill a
maggot full grown, we find its stomach full ofa similar substance,
only softer, as if mixed with a fluid, but we never find honey in the
stomach ; therefore we are to suppose it is collected as food for the
maggot, as much as honey is for the old bee.   Mr. Schirach ima-
gines  that the  semen of  the  male is  the  food of  the maggot; but
the food of the male and  the  queen maggot  has  been supposed to
be different from that of the labourers.  Reaumur says the food of
the queen maggot is different in taste from that of the common ones.
How he knew  this, who  was unacquainted with  the food of the
others, I cannot conceive.

                  Of the Excrement  of the Maggot.

   They have very little excrement, but what they  do discharge is
deposited at the bottom of  the cell; and  what at first will appear
rather extraordinary, it is  never  cleared  away by the bees, but al-
lowed to dry along with the maggot coats; and both fresh eggs and
honey are deposited in  these  cells  so circumstanced, every future
year ; so that in time the cells become nearly half full.

                       Of the Chrysalis State.

   In this state  they are  forming themselves for  a new life; they
are either entirely  new  built, or wonderfully changed, for there is
not the smallest vestige of  the old  form remaining; yet it must be
the same  materials, for  now nothing  is  taken in.  How far this
change is only the old  parts  new  modelled, or gradually altering
their form, is not easily determined.  To bring about the change,
many parts must be removed out of which the new  ones are pro-
bably formed.*   As  bees  are not  different in this  state from the

   * [It is in the  determination of these interesting questions that the minute
 researches of Swammerdam manifest their importance.  His figures demonstrate
 that the larva of the bee consists of thirteen annular segments, of which one cor-
 responds to the head, three to the thorax, and nine to the abdomen of the perfect
 insert.
   The cephalic segment supports the rudimental eyes, which resemble the ocelli
 of  other  insects in structure,  but  are colourless and semitransparent.  The
 antennae are represented by two small organs placed at the anterior angles of the
 head ;  the oral  organs are also  indicated  ; there  is a small transverse upper lip
 or  labrum, beneath which  are  two little horny parts, afterwards destined to
 become the mandibles : then "two little  parts which seem as if they were arti-
 culated " these are subsequently developed into the maxillx,- and between these
 is a mesial "small, and  somewhat prominent part, which resembles a trunk or
 tongue, and this increasing by degrees, at length indeed constitutes," says Swam-
 merdam, "the  trunk of the bee."
   We thus have evidence that the parts which so conspicuously distinguish the
 imago from the  larva, and not "entirely  new built," but are " wonderfully
 changed" by gradually altering their form and relative dimensions.
   With respect to the rest of the larva, we find that the body is furnished on each
 side with ten minute circular spiracles, a pair being placed on  each segment, with
 the exception of that which immediately follows  the head, and the terminal one 
OBSERVATIONS ON BEES.
435
common flying insects in genera], I shall  not pursue the subject of
their changes further; although  it  makes a very material part in
the natural history of insects.
   When the  chrysalis is  formed into the complete bee, it  then de-
stroys the covering of its  cell, and  comes forth.  The time it con-
tinues in this state is  easier ascertained than  either in that of the
egg or the maggot; for the bees cannot  move the chrysalis as they
do the two others.  In one instance it was thirteen days and twelve
hours exactly ; so that an egg in hatching being five days, the age
of the maggot being four days, and the chrysalis continuing thir-
teen and a half, the whole  makes twenty-two days and a half: but
how far this is accurate I wiffnot pretend to  say.   I found that the
chrysalis of a male was fourteen  days,  but this was probably acci-
dental.  When they  first  come  out they  are  of a grayish colour,
but soon turn brown.
   When the  swarm of which I  have  hitherto been giving the his-
tory has come off early  and  is a  large one, more  especially if it
was put into  too  small a hive, it often  breeds  too many for  the hive
to keep through the winter ; and in such case a new swarm is thrown
off, which, however,  is  commonly  not  a large one,  and generally
has too little  time to complete its comb, and store it with honey suf-
ficient to preserve them  through the winter.  This is similar to the
second or third swarm of the old hives.

   Of the Seasons when the different  operations of Bees take place.

   I have already  observed that the new colony immediately sets
about the increase  of their numbers,  and everything relating to it.
They had their apartments to build, both for the purpose of breed-
ing, and as a storehouse  for  provisions for the winter.   When  the
season for laying eggs is over, then is the season for collecting  ho-
ney ; therefore when  the last chrysalis  for the season comes forth
its cell is immediately filled with honey, and as soon as a cell is full
it is covered over with pure wax, and is to  be considered as store
for the winter.  This covering answers two very essential purposes:
one is to keep it  from spilling, or daubing the bees ; the other to pre-
vent  its evaporation, by which  means it is kept  fluid in  such a
warmth. They  are also employed in laying up a store of bee-bread
for the young maggots in the spring, for they begin to bring forth

which  bears the arms.  Previous to shedding the skin, the first three segments
of the. body begin to swell, and make room for the aggregated muscles which are
to put in motion the locomotive organs, attached, in the perfect insect, exclu-
sively to these segments.
   The larva being  apodal, both  the legs and wings may be regarded as being
" entirely new  built,"  and the pupa of the bee then presents an elegant disposition
and well-ordered representation of all the limbs and parts of the future bee.  Ine
antenna? and the tongue are  seen lying along the breast, and the wings and  legs
bent from the sides  of the thorax along the belly.  Some of the segments ot the
larva  are " removed," and out of these the organs of  generation appear to be
formed.] 
430          HUNTER ON THE ANIMAL  CECONOMY.
much earlier than probably any  other insect, because they retain
a summer heat and store up food for the young.
  In the month of August we may suppose the queen or queens are
impregnated by the males ;  and as the males do  not provide for
themselves, they become burdensome to the workers, and are there-
fore teazed to death much  sooner  than they otherwise  would die;
and when the bees set about this business of providing their winter
store, every operation  is over, except  the collecting  of honey and
bee-bread." At this time it would  seem as if the males were con-
scious of their danger, for they do not rest on the mouth  of the hive
in either going out or coming in, but hurry either in or out;  how-
ever they are commonly attacked by one, two, or three at a  time:
they seem to make  no resistance,  only getting away as fast as pos-
sible.   The labourers do not sting them, only pinch them, and pull
them  about as if to  wear them out; but I suspect it may  be called
as much a  natural as a violent  death.
  The whole of the males are now destroyed, and  indeed it would
have been useless to have saved any to impregnate the queen  in the
spring.  That there may be many more than may be  wanted  I can
easily believe, for this we  see  throughout nature;  but she always
times her operations well,  although there may be supernumeraries.
  When the young are wholly come forth, and either the cells en-
tirely filled, or no more honey  to  be collected, then is the time or
season for remaining in their hives for the winter.
  Although I have  now completed a hive, and no operations are
going on  in the winter months, yet the history of this  hive is imper-
fect till it sends forth a new swarm.
  As the common bee is very susceptible of cold, we find as  soon
as the cold weather sets in they become very quiet or still, and re-
main  so throughout the winter,  living on the produce of the summer
and autumn ; and indeed a cold day in the  summer is sufficient  to
keep them at home more so than  a shower  in a warm day; and if
the hive is  thin and much exposed, they will hardly move in  it, but
get as close together as the comb will let them, into a cluster.   In
this manner they appear to live through the winter; how7ever, in a
fine  day  they become  very lively and active, going abroad, and
appearing to enjoy  it, at which time they get  rid  of their excre-
ment ; for I fancy they seldom throw out their excrement when in
the hive.   To prove this,  I confined some bees in a small  hive, and
fed them  with honey for some days, and the moment  I let them out
they flew, and threw out their excrement in large  quantities ; and
therefore in the winter, I presume, they retain the contents of their
bowels for a considerable  time.  Indeed, when we consider their
confinement in the winter, and  that they have no  place to deposit
their  excrement, we can  hardly account for the whole of this
operation in them.   Their excrement  is of a  yellow colour, and
according to their confinement it  is found higher and higher up in
the intestine, almost as high as the crop.
   Their life at this season of the year is  more uniform,  and may 
OBSERVATIONS ON BEES.
437
be termed simple existence, till the warm weather arrives  again.
As they now subsist on their summer's industry, they would seem
to feed in proportion to the coldness of the season ; for from  expe-
riment I found the hive grow lighter  in  a  cold week than it did
in a warmer, which  led to further experiments.  I first made an
experiment  upon a  bee-hive, to ascertain  the  quantity of honey
lost through  the  winter.   The  hive  was  put into the  scale
November 3, 1776.
                                          oz. drams.
              November 10th,  it had lost  2  7
                         17th,---------4  2h
                         24th,--------3  7i
                December 1st,--------8  2
                          8th,  --------  2  1
                         15th,--------5  2
                          22d,--------4  3
                         29th,--------5  4
            1777.  January 1st,--------2  5
                         12th,--------5  2
                         19th,--------3  4
                         26th,--------3  \h
                 February 2d,--------5  0
                          9th,   --------  7  0
                           The whole     72  \h

  Although an indolent state is  very much  the  condition of bees
through the winter, yet progress is making in the queen towards a
summer increase.  The eggs in the oviducts are beginning to swell,
and I believe  in the month of March she is ready to lay them,  for
the young bees are to swarm in June; which constitutes the queen
bee to be the  earliest breeder of any insect we  know.  In conse-
quence of this, the  labourers become  sooner  employed  than any
other of this tribe of insects.   This both  queen and  labourers are
enabled to accomplish, from  living in  society through  the winter;
and  it becomes  necessary in them, as they have their  colony to
form early in the summer, which is to provide for itself for the
winter following.  All this requires the process  to be  carried for-
ward earlier than by any other  insects, for these are only to  have
young which  are to take care of themselves through  the summer,
not being under the necessity of providing for the winter.
  In the month of April I found in  the cells young bees, in all stages,
from the egg  to the chrysalis state, some of which were changed in
colour, therefore were nearly arrived at the fly state, and probably
some might have flown.
  As this season is  too early for collecting the provision of the
maggot abroad, the store of farina comes now into use; but as soon
as flowers begin  to blow, the bees gather the fresh, although they
have farina in store, giving the fresh the preference.
                               38* 
438          HUNTER ON THE ANIMAL CECONOMY.
                        Of the Queen.

  The queen bee, as she is termed, has  excited more curiosity than
all the others, although much more belongs to the labourers.   From
the number of these, and from their exposing themselves, they have
their history much better made  out; but as there is only one queen,
and she scarcely ever seen, it being only the effects  of her  labour
we can come at, an opportunity has been given to the ingenuity of
conjecture, and  more has been said than can well be proved.  She
is allowed to be bred  in the common way, only that  there is  a
peculiar cell for her in  her first stage; and  Reaumur  says, " her
food  is different when  in  the maggot  state;"  but as there is
probably but one queen, that the whole  might not depend on one
life, it is asserted that the labourers have a  power  of forming  a
common maggot into a queen.  If authors had given us this as an
opinion only, we might have passed it over  as  improbable ;  but
they have endeavoured to prove it by  experiments,  which require
to be examined.  And  for that purpose I  shall give what they  say
on that head, with my  remarks  upon it.

                  Abstracts from Mr. Schirach.

  The following experiments were made to  ascertain the origin of
the queen  bee  :—" In  twelve  wooden  boxes were  placed  twelve
pieces of comb, four inches square, each  containing both eggs  and
maggots, so suspended that the  bees could come round every part
of the comb: in each  box was  shut up a handful  of working bees.
Knowing that  when bees are forming a queen they  should be con-
fined,* the boxes were kept shut  for two days.   When examined
at the end of that  period (six  boxes only were opened), in all of
them royal cells were begun, one, two, or three in each; all of
these containing a maggot  four days old.  In four days, the other
six boxes were  opened, and  royal cells found in  each, containing
maggots five days  old, surrounded by a large provision of jelly;
and one of these  maggots  examined in  the mircroscope, in every
respect resembled a working bee.
   " This experiment was repeated, and the maggots selected to be
made  queens were three days old ; and  in  seventeen days there
were found in  the  twelve  boxes  fifteen  lively, handsome queens.f
These experiments were made  in May, and  the bees were allowed
to work great  part of the  summer; the  bees were examined one

  * How he came to know this I cannot conceive, for nothing a priori could give
such information.
  f Now this account is not only improbable, but it does not tally with itself.
First, it is not probable that a handful of bees should  or would set about making
two, three, or four queens, when we do not  find that number in a large hive;
and  secondly, it seems inconsistent  that only fifteen should be formed out of
twelve parcels, when some of the former parcels had four young queens. 
OBSERVATIONS ON BEES.
439
by one, but no drone could be discovered, and yet the queens were
impregnated, and laid their eggs.*
  "The above experiment was repeated with pieces of comb con-
taining eggs only, in  six boxes, but no  preparations  were made
towards producing a queen.f
  " The experiment of producing a queen bee from a maggot was
repeated every month of the year, even in November.^
  "A maggot three days old was procured  from a friend, inclosed
in an ordinary cell, and shut up with a piece "of comb, containing
eggs  and maggots.  That three days old was formed into a queen,
and all the other maggots and eggs were destroyed.^
  " In above a hundred experiments a queen has been formed from
maggots three days old."||
   Wilhelmi observes  that a queen  cell, which is made while the
bees are shut  up, is formed by breaking down  three common cells
into one, when the maggot is placed in the  centre, after which the
sides are repaired.
  A young queen  lately hatched was  put  into a hive, which had
been  previously ascertained to contain no drones, and whose queen
was removed ; and yet the young queen laid eggs.H   In repeating
Mr. Schirach's experiment, he shut up four pieces of  comb, with
one  maggot in each; after  two days the  maggot were all dead,
and  the bees had desisted from labour.**
   A  piece of comb from which all the eggs and maggots had been
removed, was shut up  with  some  honey and a certain  number of
workers:  in a short time they became very busy, and upon the
evening of the second day three hundred eggs  were found in the
cells.ff  He repeated this experiment with the  same result, and the
bees  were left to  themselves; they placed  queen  maggots in the
queen cells, newly constructed, and others  in  male cells;  the rest

  * Here is a wonder of another kind: queens laying eggs, which (we must sup-
pose Mr. Schirack meant we should believe) they hatched, without the influence
of the male.
  X Why eggs, which we must conceive hatched, and produced maggots, did not
form queens, one cannot imagine.
  X In which month, as bees never swarm, there could be no occasion for mothers,
or supernumerary  queens,  and  still each  experiment produced a handsome
queen.  This is as singular an observation as any.  In this country, and in all
similar ones, bees hardly breed after July, and by  the beginning of September
there  is hardly a chrysalis  to be seen ; yet these bred till November, and even
laid eggs.
  § Why did the bees destroy them in this experiment, and not in others 1
   || The working bees from the above experiments are considered as all females,
although the ovaria are too small for examination.
  It wmild appear that a maggot three days old was of the best age for this ex-
periment, yet one should have conceived that a maggot two days old would soon
be fit.
  ^ There is no mystery in this; but did they hatch 1
  ** This is the most probable event in the whole experiments.
  ff This would show that labourers can be changed into queens at will, and that
neither they nor their eggs require to be impregnated ; if this was the case, there
would be no occasion for all the push in making a queen or a male. 
440
HUNTER ON THE ANIMAL CECONOMY.
were left undisturbed.  He again took two pieces of comb which
contained neither eggs nor maggots, and shut them up with a cer-
tain number of workers,  and carried  the  box  into a stove ;  next
evening, one of the  pieces of comb contained several eggs, and the
beginning of a royal cell that was empty.
  Besides the short  observations contained in the notes, I beg leave
to observe that I have  my doubts respecting the whole of  these
experiments, from  several circumstances which occurred in  mine.
The three following facts  appear much against their probability;
first, a summer's evening in this country is commonly too  cold for
so small a parcel of bees to be lively, so as  to set about new opera-
tions; they get so benumbed that they  hardly recover in the  day,
and I should suspect that where these experiments were made (and
indeed some are said to  have been tried in  this  country), it is also
too cold : secondly, if the weather should happen to be so warm as
to prevent this effect, then they are so restless that they commonly
destroy themselves; or wear themselves out; at  least, after a few
days' confinement we find them mostly dead: and thirdly, the ac-
count given  of the formation of a royal cell, without mentioning the
above inconvenience, which is natural to the experiment, makes me
suspect  the whole to be fabricated.  To obviate the first objection
which I found from experiment to prevent any success that other-
wise might arise, I put my parcel of bees, with their comb, in which
were eggs, as also maggots, and in some of the trials there  were
chrysalises,* into a  warmer  place, such as  a glass frame over tan,
the surface of which was covered with mould to prevent the rising
of unwholesome air; but  from knowing that the maggot was fed
with bee-bread, or farina,  I took care to introduce  a  cell or two
with this substance, as also the flowers of  plants  that  produce  a
great deal of it, likewise  some honey for  the  old ones.  In this
state my bees were preserved  from the cold, as also provided with
necessaries;  but after being confined  several days, upon  opening
the door of  the hive, what were alive  came to the door, walked
and flew about, but  gradually  left it, and on examining the combs,
&c, I  found the maggots dead, and  nothing like any operation
going on.
  The queen, the mother of all, in whatever way produced, is a true
female,  and  different from  both the labourers and the male.  She is
not so large in the trunk (abdomen) as  the male, and appears to be
rather larger in every part than the labourers.  The scales on the
under surface of the belly of the labourers, are not uniformly of the
same colour over the whole scale ; that part being lighter which is
overlapped by the terminating scale above,  and  the uncovered part

  * I choose to have some chrysalises, for I supposed that if my bees died or flew
away, the chrysalises when  they came out, which would happen in a few days,
not knowing where to go, m.ght stay and take care of the  maggots that might be
hatchea from the egg; but to my surprise, I found that neither the eggs hatched,
nor did the chrysalises come forth; all died; from which I began to suspect
that the presence of the  bees was necessary for both. 
OBSERVATIONS ON BEES.
441
being darker; this light part does not terminate  in a straight line,
but in two curves, making a peak, all which gives the belly a lighter
colour in the neighbouring bees ; more especially when it is pulled
out or elongated.
   The tongue of the female is considerably shorter than that of the
labouring bee, more like that of the male;  however, the tongues of
the labourers are  not in all of an equal length, but none have it  so
short as the queen.
   The size of the  belly of the femalis of such animals varies a little,
according to the condition  they are in; but  the  belly of the male
and the labourer has but little occasion to change its size,  as they
are at all times nearly in the same  condition with  regard to fat,
having always plenty of provision ; but the true female varies very
considerably;  she is ofa different size and shape in the summer to
what she is  in the winter;  and  in the winter she  has what  may be
called her natural size and shape; she is  upon the whole rather
thicker  than the labourer, and  this  thickness is  also in the belly,
which probably arises from the circumstance of  the oviduct being
in the winter pretty large, and  the  reservoir for  semen full.  The
termination  of the belly is rather more peaked than in the labourers,
the last scale being rather  narrow from side to  side, and  coming
more to a point at the anus.  The scales at  this  season are more
overlapped,  which can only be  known by drawing  them out.  In
the spring and summer she is more easily distinguished; the  belly
is not only thicker, but considerably longer than formerly, which
arises from  the increase of the eggs.  We distinguish a queen from
the  working bee simply by size,  and in some degree by colour;
but this last is not so easily ascertained, because the difference in
the colour is not so remarkable in the back, and  the only view we
can commonly get  of her is on this part; but when a hive is killed,
the best way is to collect all the bees, and  spread them on white
paper, or put  them into water, in a  broad, flat-bottomed, shallow
white-dish,  in which  they seem ;  and by looking at them  singly,
she may be discovered.  As the queen breeds the first  year she is
produced, and the oviducts never entirely subside, an old queen  is
probably thicker than a new-bred  one, unless indeed the oviducts
and the eggs form in the chrysalis state, as in the silk-worm, which
I should suppose they did.   The queen is  perhaps at  the  smallest
size just as  she has  done  breeding, for as  she  is to lay eggs  by
the month  of March, she must  begin early to fill again ; but I
believe her  oviducts are never emptied, having at all times eggs in
them, although but small.   She has fat in her belly, similar to the
other bees.
   It is most probable that the queen which  goes off with the swarm
is a young one, for the males go off with the swarm to impregnate
her, as  she  must be impregnated the same year,  because she breeds
the same year.
   The queen has a sting similar to the working bee, 
442          HUNTER ON THE ANIMAL CECONOMY.
             Of the Number of Queens in a Hive.

  I believe a hive or swarm  has but one queen, at least I have
never found  more  than one  in a swarm, or in an old hive  in the
winter; and  probably  this is what constitutes a hive ; for when
there are two queens, it is  likely  that a division may begin to take
place.  Supernumerary queens are mentioned by Riem, who asserts
he has  seen them killed by the labourers, as well as the males.
  November  18th, 1788, I killed a  hive that had not swarmed the
summer before, and which was to appearance ready to swarm every
day; but when I supposed  the season for swarming was over, and
it had not  swarmed, I began to suspect that  the reason why it did
not was owing to  there being no young queen or queens ; and I
found only one.  This is a kind of presumptive  proof that I was
right in my conjecture ; unless it be supposed, that when they were
determined not no swarm,  they  destroyed every queen except one.
In a hive  that died, I found no males, and only one queen.   This
circumstance, that  so  few queens  are bred, must arise from the
natural security the queen  is in from the mode of their society; for
although there is but one  queen in a wasp's, hornet's, and humble
bee's nest  or  hive, yet these breed  a great number of queens; the
wasp and hornet some hundreds; but not living in society during
the winter, they are subject to great destruction,  so that probably
not one in a  hundred  lives to breed in the summer.  I have said
that the queen leaves off laying in the month of July;  and  now she
is to be impregnated by the males before they die.   Mr. Riem as-
serts, he has seen the copulation  between the male and the female,
but does not  say at what  season.  I should doubt this ;  but Mr.
Schirach supposes  the  queen  impregnated without copulation.  I
know not  whether he means by  this that she is not impregnated at
all, and supposes, like Mr.  Debraw, that the eggs are impregnated
after they are laid, by a set of small drones, who pass  over the
cells, and  thrust their tails  down into the cell, so as to besmear the
egg.*  Mr. Bonnet does not consider it necessaiy that the drones
should  be  small for this purpose, for he saw a  large drone passing
over the cells of a piece of comb, stopping at every one which con-
tained an egg, but at no other, and giving a knock with his  tail on
the mouth of  the cell three times; this he supposed was the mode
of impregnating  the eggs.  The number  three has always been a
famous number; but it  will not do where there are no males, which
is the case of a hive in  the spring, the time when the queen is most
employed  in laying eggs ;  which made him  suppose the use  of the
males was to feed the maggots with their  semen.   It is probable
that the copulation  is like that of most other insects.   The copula-
tion  of the humble bee I have  seen, it is similar to  the common fly.
The sting  is extended at the time, and turned  up  on the back, be-

  * Mr.  Debraw, knowing  the  drones died in the latter end of summer or the
autumn, was obliged to suppose a small set of males, that lived through the win-
ter, for that  purpose. 
OBSERVATIONS ON BEES.
443
tween  the two animals; they are some  time  in this act.   In the
hornet it is the same.  The circumstances relative to the impreg-
nating the queen not being known, great room has been given for
conjecture, which, if authors had presented as conjectures only, it
would have shown their candour; but they have'given, what in
them were probably conceits, as facts.


                       Of the  Male Bee.

   The male  bee is  considerably  larger than  the labourers: he is
even larger than the queen, although not so long when she is in her
full state with eggs:  he is considerably thicker than either, but not
longer in the same proportion:  he  does not terminate  at the anus
in so sharp a point; and  the opening between  the two last scales
of the back and belly is larger, and  more under  the belly than in the
female.  His  proboscis is much shorter than that of the labouring
bee, which makes me suspect he does not collect his  own  honey,
but takes that which is brought home by the others; especially as
we never find the males abroad on flowers, &c, only  flying about
the hives in hot weather, as if taking an airing;  and when we find
that the male  of the humble bee, which collects  its own food, has
as long a proboscis or tongue as  the female,  I think it is from all
these facts reasonable to suppose the male of the common bee feeds
at home.  He has no string.
   The males, I believe, are later in being bred than the labouring
bee.   As they are only produced to go off with a hive, they are
not  so early brought forth ; for in the month of April I killed a hive,
in  which I found maggots and chrysalises, but did  not  find any
males among the latter : the maggots are too young for such inves-
tigation ; but  about the 20th of May  we observed males:  they are
all very much of the same size.  In the month  of August, probably
 about the latter  end, we may suppose they impregnate the queen
 for the next year, and about the latter end of the same month, and
 beginning of September, they are dying, but seem to be hastened to
 their end by the labourers.  In 1791, as early  as the 19th of June,
 I saw the labourers  killing the males of  a  hive, or rather of  a
 swarm, that has  not yet swarmed, but was hanging out; this, how-
 ever, was out of the common course.   They appear to be sensible
 of their fate, for they hurry in and out of the hive as quick as pos-
 sible,  seemingly with a view to avoid the labourers;  and  we find
 them  attacked by the labourers, who pinch  them with their for-
 ceps,  and when  they are so  hurt, and fatigued with  attempts  to
 make their escape, as not to  be able to  fly, they are thrown over
 on the ground and left to die.  That this is the fate of every male
 bee is easily ascertained, by examining every bee in the hive when
 killed for the  honey, which is after this season  ; no male being then
 found in it.   Bonnet supposes them starved to death, as he never
 saw wounds on  them.  In the  course of a winter I  have killed
 several hives, some as late as April, and  in such a way as  to pre- 
444          HUNTER ON THE ANIMAL CECONOMY.
serve every bee, and after examining  every one entirely, I never
perceived one male of any kind ;  although it has been asserted there
are two sizes of males, and that the small are preserved through tho
winter to impregnate the queen.

                     Of the Labouring Bee.

  This class, for  we  cannot call it either sex or species, is  the
largest in number of the whole community;  there are thousands of
them  to one queen, and probably  some hundreds to each male, as
we shall see by and by.  It is to be supposed they are the only bees
which construct the whole hive, and that the queen has no other bu-
siness but to lay the eggs: they are the only bees that bring in ma-
terials ; the only ones we  observe busy abroad;  and,  indeed, the
idea of any other is  ridiculous, when we consider the disproportion
in numbers as well as the employment of the others, while the work-
ing bee has nothing to take off its  attention  to the business of  the
family.   They are smaller than either the queen or the males:  not
all of equal size, although the difference is not very great.
  The queen and  the working bees are so much alike that the  lat-
ter would seem to be  females on a different scale : however, this
difference is not so observable in the beginning of winter as in  the
spring, when the queen is full of eggs.  They are all females in con-
struction, having the  female  parts, which are extremely small, and
would be easily overlooked by a  person not very well  acquainted
with the parts in the queen:  this  has been  observed by Mr. Riem ;
indeed, one might suppose that they were only young queens, and
that they became queens after a certain age; but this is not the case.
They all have stings, which  is  another thing that  makes them
similar to the queen.   From their  being furnished with an instru-
ment of defence and  offence, they  are endowed with such powers
of mind as to use it, their minds being extremely irritable; so much
so that they make  an attack  when not meddled with, simply upon
suspicion, and  when  they do attack  they  always sting; and yet,
from the circumstance of their not being able to disengage the sting,
one should suppose they would be more cautious in striking with it.
When they attack one another, they seldom use  it, only their pin-
cers: yet I  saw two  bees  engaged, and one stung the other in  the
mouth, or thereabouts, and the sting  was  drawn from the body to
which it belonged, and the one who  was stung ran very quickly
about with it; but I  could not catch  that bee to observe how  the
sting was situated.
  As they are the collectors of honey, much  more than what is for
their own use, either immediately or in future, their tongue is pro-
portionably fitted for that purpose: it  is considerably longer than
that of either the queen or the male, which fits them to take up the
honey from the hollow parts of flowers, of considerable depth.
The mechanism is very curious, as will be explained further on. 
OBSERVATIONS ON BEES.
445
  The number of labourers in a hive varies very considerably.

  In one hive that I killed there were     ....   3338
  In another.........   4472
  In one that died there were......2432
  That I might guess at the number of bees from a given
    bulk, I counted what number an alehouse pint held, when
    wet, and found it contained.....2160
  Therefore, as some swarms will fill two quarts, such must
    consist of near       .......9000

      Of the Parts concerned in the Nourishment of the Bee.

  Animals  which only swallow food for themselves, or whose
alimentary organs are fitted wholly for their own nourishment, have
them adapted to that use only; but  in many, these organs are com-
mon for more purposes, as in  the pigeon, and likewise in the bee.
In this last,  some of the parts are used as a temporary reservoir,
holding both that which is for the  immediate nourishment of the
animal, and also that which is to be preserved for a future day, in
the cells  formerly described; this last portion is therefore thrown
up again, or regurgitated.  As it is  the labourers alone in the com-
mon bee  that are so employed, we  might conceive this  reservoir
would belong only to them; but  both the queen and males, both in
the common and humble  bee, have  it, as also, I  believe, every one
of the bee tribe.
  As the bee is a remarkable instance of regurgitation, it  is neces-
sary the  structure of the parts concerned in this operation, and
which are also connected with digestion, should be well considered.
Ruminating animals may be reckoned regurgitating animals, but in
them  it is for the purpose of digestion entirely in themselves.   But
many birds may be called regurgitating animals, and in them it is
for the purpose  of feeding  their young. Crows fill  their fauces,
making a kind  of craw, out of which  they throw back  the food
when they feed their young; but the most remarkable  is  the dove
tribe,  who first fill their craw, and then throw it up into the beak of
their young.*  The bee has  this power to a remarkable degree, not
however for the purpose of feeding the young, but it is the mode of
depositing their store in the  cells when brought home.
  In none  of the  above-mentioned regurgitating animals are the
reservoirs containing the food the  immediate  organ  of digestion ;
nor does the reservoir  for the honey in  the  bee appear  to  be its
stomach.
   The tonguef of the bee is the first of the alimentary organs to be

  * See Observations on certain parts of the Animal CEconomy, p. 191  [p. 149
of the present edition].
  t The part which Hunter so calls includes the maxilla: and their rudimental
palpi, the labium and its palpi, as well as  the tongue properly so called, which
seems, indeed, to be strictly an inordinate development of the labium, or lower
                             39 
440           HUNTER ON THE ANIMAL CECONOMY.
 considered:  it is of a peculiar structure, and is probably the largest
 tongue of any animal we know,for its size.   It may be said to con-
 sist of three  parts respecting its length, having three  articulations.
 One, its articulation with  the head, which  is  in  some  measure
 similar to our larynx (mentum). Then comes the body of the tongue,
 which  is  composed of two  parts; one, a kind  of base (labium),
 on which the other, or  true  tongue (lingua), is  articulated.  The
 first part (labium) is principally a horny substance, in which there
 is a groove,  and it is articulated with the  first or larynx (mentum);
 on the end of this is fixed the true tongue, with its  different parts.
 These two parts of the  tongue are as it were inclosed laterally by
 two horny scales (maxillce), one on each side, which  are  concave
 on that side next to the tongue; one edge  is thicker than the other,
 and they do  not  extend so far as the  other parts.  Each of these
 scales is composed of two parts, or scales, respecting its length, one
 articulated with the other:  the first of those scales (cardo)  is articu-
 lated with the common base,  at the articulation of the first part of
 the tongue, and  incloses laterally the  second part of the tongue,
 coming as far forwards  as the third  articulation: on the  end of
 this is  articulated  the second scale  (lobus),  which continues the
 hollow groove that incloses the tongue laterally; this terminates in
 a point.   These  scales have some hairs on their edge.
   On the termination of the second part is placed the true tongue,
 having two lateral portions or processes on each  side, one within
 the other; the external (palpus labialis) is the largest, and is some-
 what similar to the before-mentioned scales.   This is composed of
 four parts, or rather of one large part, on  which  three smaller  are
 articulated, having motion on themselves.   The  first,  on which the
 others stand,  is articulated at  the edges of the tongue, on the basis
 or termination of the  last-described part  of the tongue;  this  has
 hairs on its edge.
  A little further forwards on the edges of the tongue are two small
thin processes (paraglossce), so small as hardly to be seen with  the
naked eye.  The middle part  of all, of which these lateral parts are
 only appendages, is the true tongue (lingua).   It is something longer
than any of the before-mentioned lateral portions, and is not horny
as the other parts are, but  what may be  called fleshy, being soft
and pliable.  It is composed of short sections,  which  probably  are
so many short muscles, as  in fish, for they are  capable of moving it
in  all directions.  The tongue itself  is extremely villous, having
some very long villi at the point, which act, I  conceive, somewhat
like capillary tubes.*
  This whole apparatus  can be folded up,  into a very small  corn-
lip of the ordinary trophi.   I have inserted in the text the terms by which the dif-
ferent parts described by Hunter are known to entomologists.]
  * [Mr. Kirby observes, " The upper part of this tongue is cartilaginous, and
 remarkable for a number of transverse rings : below the middle it consists of a
membrane, longitudinally folded in inaction, but capable of being distended to a
considerable size.  This membranous bag receives the honey, which the tono-ue
as it were,laps from the flowers, and conveys  it to the pharynx. 
OBSERVATIONS ON BEES.
447
pass, under the head and neck.  The larynx falls back info the neck,
which brings the extreme  end of the first portion of  the  tongue
within the upper lip, or behind the two teeth; then  the whole of
the second part, which consists of five parts,  is  bent  dowm  upon
and under this first part, and  the  two  last scales are also bent
down over the whole, so  that the  true tongue  is  inclosed laterally
by the  two second horny scales, and over the whole  lie the two
first.
   The oesophagus, in all  this tribe of insects, begins just at the root
of the tongue, as in other animals,* covered anteriorly  by a  horny
scale, which terminates  the head, and which  may be called the
upper lip or the roof of the mouth.   It  passes  down through the
neck and thorax, and  when got into the abdomen it immediately
dilates into a fine transparent bag, which is the immediate receiver
of whatever is swallowed.   From this the food (whatever it be) is
either carried further on  into the  stomach to be digested, or is  re-
gurgitated for other purposes.  To ascertain this in some  degree
in living bees, I caught them going out early in  the  morning, and
found this bag quite empty:  some time after I caught others return-
ing home and found the  bag quite full of honey, and some of it had
got into the stomach.   Now I suppose that which was  in the craw
was for the purpose of regurgitation, and as probably they had fasted
during the night, part had gone  on further for digestion.  What-
ever time the contents of this reservoir may be retained, we never
find them altered, so as to  give the idea of digestion having taken
place: it is pure honey.   From this bag the contents can be moved
 either way; either downwards to the stomach, for  the immediate
 use of the animal itself, or back again, to be thrown out as store for
 future aliment.
   The stomach arises from the lower end and a little on the right side
 of this bag.  It does not gradually contract into a stomach, nor is the
 outlet a passage directly  out, but  in the centre of a projection which
 enter some way into  the  reservoir, being rather an inverted pylorus,
 thickest at its most projecting part, with a very small opening in the
 centre, of a peculiar  construction.  This inward projecting part is
 easily seen through the  coats of  the reservoir, especially if full  of
 honey.
   The stomach begins immediately on the outside of the reservoir, and
 the same part which projects into the reservoir is continued some way
 into the stomach, but appears to have no particular construction at this
 end, and therefore it is only fitted  to prevent regurgitation into the re-

   * This observation appears to have been  overlooked by entomologists,  who
 continued to believe that the  opening of the pharynx was situated below the pro-
 boscis in bees, until the researches of Savigny on the oral organs  of these insects
 and of the Lepidoptera were made public.  Cuvier, in his Analyse des fravaux
 de la Classe des Sciences Mathematiques et Physiques de P Institut, pendant I Annee
 1814, observes, "On avait cru voir que l'ouverture du pharynx etait situee en
 dessous  de cette trompe ou de cette levre,  tandis que dans les masticateurs ordi-
 naires elle l'est en dessous;  mais c'etait une erreur ; le pharynx  est toujours sur
 la base de la trompe, et il y est meme garnis de parties interessantes a reconnaitre,
 et dont M. Savigny donne une description detaillee. "  p. 25.] 
448
HUNTER ON THE ANIMAL CECONOMY.
servoir, as such would spoil the honey.   This construction of parts is
well adapted for the purpose, for the end projecting into the reservoir
prevents any honey from getting into the stomach, because it acts there
as a valve; therefore whatever is taken in mustbe by an action of this
valvular part.  The stomach has a good deal the appearance of a gut,
especially as it seems to come  out from a bag.   It passes almost di-
rectly downwards in the middle of the abdomen.  Its inner surface is
very much increased, by having either circular valves, somewhat like
the valvulae conniventes in the human jejunum, or spiral folds, as in the
intestine of the shark, &c.; these may be seen through the external
coats.   In this part the food undergoes the change.  Where the sto-
mach terminates is not exactly to be ascertained,but it soon begins to
throw itself into convolutions and becomes smaller.
   The intestine makes two or three twists upon itself, in which part
it  is enveloped in the ducts, constituting the liver and probably the
pancreas, and at last passes on straight to the termination of the
abdomen.   Here it is capable of becoming very large, to serve upon
occasion as a reservoir, containing a large quantity of excrement;
it then contracts a little, and opens under the posterior edge of the
last scale of the back, above the sting  in the female and labourers,
and the penis in the male.*

                     Of the Sense of Bees.

   Bees certainly have the five senses.   Sight none can doubt.  Feel-
ing they also have;  and  there is every reason for supposing they
have likewise taste, smell, and hearing.  Taste we cannot doubt;
but of smell we may not have such proofs ; yet, from observation, I
think they give strong signs of  smell.   When bees are hungry, as a
young swarm in wet  weather, and are in a glass hive, so that they
can be examined, if we put some honey into the bottom it will imme-
diately breed a  commotion; they all seem  to be  upon the scent;
even if they are weak  and hardly  able to crawl,  they will  throw
out their proboscides as far as possible to get to it, although the light
is  very faint.   This last appears to arise more from smell than see-
ing.  If some bees are let loose in a bee-hive, and do not know from
which house they came, they will take  their stand upon the outside
of some hive or hives, especially when  the evening is  coming on ;
whether this arises from the smell of the hives or sound I can hardly
judge.

                     Of the  Voice of Bees.

   Bees may be said to have a voice.  They are certainly capable of
forming several  sounds.  They give a sound when flying, which
they can vary according to circumstances.  One accustomed  to
bees can immediately tell when  a bee makes an attack by the sound.

  * [See Preps. 476, 477, C01, 602,  603, 604, 605.  Physiological Series, Hun-
terian Museum.] 
OBSERVATIONS ON BEES.
449
These are probably made by the wings.  They may be seen stand-
ing at the door of their hive,  with  the  belly' rather  raised,  and,
moving  their wings, making a  noise.  But  they produce  a noise
independent  of their wings ;  for if a bee is  smeared all over with
honey, so as to make the wings stick together, it will be found to
make a  noise which is shrill and peevish.  To ascertain this further,
I held a bee by the legs with a  pair of pincers, and observed it then
made the peevish noise, although  the wings were perfectly still: I
then cut the wings off,  and found  it made the same noise.  I ex-
amined  it in water, but it then did not produce the noise till it was
very much teased, and then it made  the same kind of noise, and I
could observe the water, or  rather the surface of contact of the
water, with  the air at the mouth  of  an air-hole at the root of the
wing, vibrating.   I have observed  that they, or some  of them,
make a noise the  evenings before they swarm, which is  a  kind of
ring, or sound of a small trumpet: by comparing it with the notes
of the piano-forte, it seemed to be the same with the lower  A of
the treble.
                      Of the  Female Parts.
   I may here observe  that insects differ from most of the  classes of
animals above them in having their eggs formed in the ducts along
which they  pass, not in a cluster on the back, as  in some  fish (for
instance, all of the ray kind, or what are called the amphibia), in
the bird, and as is supposed in the  quadruped;* from thence  the
eggs  are taken up, and by  the  ducts are  carried along to their
places of destination.
                        Of the  Oviducts.
   The  female of the common bee, similar to all the females of the
bee tribe, has six oviducts on each  side, beginning by very  snnall
 and almost imperceptible threads, as high as the chest;  they then
 form one cord coiled up, or  pass  very serpentine, and  become
 larger and larger  as they approach the anus, owing to the  gradual
 increased size of the eggs in them, which  are now more distinct,
 and give the duct a sort of interrupted appearance toward the lower
 end  The six ducts, when full of eggs, make a kind of quadrangle,
 then  all  unite into one duct,  which enters the duct common to it
 and the oviducts of the other side.  The ducts common  to the  six
 oviducts on each side  are extremely tender, so much so that it is dif-
 ficult to save them. The duct common  to those on both sides may
 be called the vagina, and it is continued to  the anus or termination
 of the belly.
                       Of the  Male Parts.
   The  male parts of generation in the common bee are much larger

   * [This supposition, that the ova of the mammalia are formed in the ovaria,». e
 in  a cluster attached  o the dorsal aspect of  the abdomen, and not in the duct
 along which they pass, is now proved incontestably by the researches of V. Baer
 and other physiologists.]
39* 
450
HUNTER ON THE ANIMAL CECONOMY.
than in the humble  bee.  This we suppose necessary, considering
the vast number of eggs the common bee lays more than the hum-
ble bee does.
   The external parts of generation of the male bee are rather more
under the belly than in the others of this tribe, not  so much at the
termination  of the belly, and they are rather more exposed, the two
last scales, especially the under one, not projecting  so  much ;  the
two holders  are not so projecting  beyond their  base, nor are they
so hooked or sharp as in  the humble bee; hardly deserving  the
name of holders.  From the external parts passes up into the abdo-
men a  pretty large sheath, whose termination  incloses the glans
penis.   It is a bulbous  part, having a dark-coloured  horny part
upon it, which has two processes near its opening externally, one on
each side, of a yellow colour ; it has another process, which is white,
and seems to be a gland.   It can be made to pass along this sheath
or prepuce, and appear externally : I have  been able, with a pair of
forceps, to invert the sheath, beginning externally at the  mouth, and
pulling out a little at a time, by shifting my hold, till the glands has
appeared externally.
   The internal parts are the testicles, with their  appendages.  The
testicles are  two small oblong bodies, lying near the  back,  having
a vast number of air vessels, passing into them, and  ramifying upon
them.  They are  of a pale yellowish  colour.   From  their lower
ends pass  down ducts, which may be  called  vasa  deferentia, and
which enter  two bags : these two  bags, into which  the  vasa defer-
entia enter, are probably reservoirs for the semen.  From the union
of these two bags passes out a duct, which runs towards  the ter-
mination of the abdomen, and ends in the penis.  These three parts,
namely, testicles with their ducts, the two bags, and the duct arising
from them, which I  have termed urethra, are all folded on each
other, so as  to appear  as one body.
  In the introduction to this account of bees I observed, that several
things  in  their ceconomy  might escape  us if we considered them
alone, but  might be made  out in other insects: an instance of this
occurs in the impregnation of the female bee.   The death  of the
males in the  month of August, so  that not one is left, and  yet the
queen to breed in the month of March, must  puzzle any one not
acquainted with the  mode of impregnation of  the females  of most
insects.  Insects,  respecting the  males, are  of two kinds : one,
where  the male lives through the winter, as well as the females;
and the other, where  every male  of that  species dies  before the
winter comes on; among which may be considered, as a third, those
where both male and female die the" same year.  Of the first, I shall
only give the common  fly as  an instance ; of the  second,  I shall just
mention all of the bee tribe; and the third maybe illustrated  in
the silk-worm moth.   The mode of impregnation in the first is its
being continued uninterruptedly through the whole period of layin*
eggs; while  in the  second, the copulation is in store;  and in the
third the female lays up, by the copulation, a store of  semen, al- 
OBSERVATIONS ON BEES.
451
though the male is alive.  Of this I shall now give an explanation
in the silk-moth, which may be applied to the bee, and many other
insects.
  In dissecting the  female  parts  in the silk-moth, I  discovered a
bag lying on what may be  called  the vagina, or common oviduct,
whose mouth or opening was external, but it  had a canal of com-
munication between it  and the common  oviduct.   In  dissecting
these parts before copulation I found  this bag  empty, and when I
dissected them after, I found it full.  Suspecting this to contain the
semen of the male, I immediately  conceived the  following experi-
ment.  I opened the female as soon as the male had  united to her,
and found the  penis in the opening of this bag, and by opening the
duct where the penis  lay 1 observed  the semen  lying on  the end
of the penis.   In another,  I observed the bag  to fill in the time of
copulation ; and in a pair that died in the act,  I found the penis in
this passage.
  When we consider the impregnation of the egg in the silk-worm,
we may observe the following circumstances:
  First, many of the ova are completely formed, and  covered with
a hard shell, before copulation; secondly, the  animals  are a vast
while in the act of copulation; and, thirdly, the  bags at the anus
are filled during the time of copulation.  From the first observation
it appears that the  egg  can receive the male influence through the
hard or horny part  of the  shell.  To know how far the whole, or
only a part of the  eggs, were impregnated by each  copulation, I
made the following  experiments.*   I took a female  just emerged
out of her cell, and put a male to her, and allowed them to be connect-
ed their full time.  They were in copulation ten hours.  I then put
her into a box by herself, and when she laid her eggs, I numbered
the different parcels as she laid them, viz., 1, 2, 3, 4,  5;  these eggs
I preserved, and in the  summer following I perceived that the No.
5 was as  prolific as  the No. 1 ; so that this  one copulation was
capable of impregnating the whole brood ; and therefore the male
influence must go either along the oviduct its whole length, and  im-
pregnate the incomplete eggs as well as the complete,  which  ap-
pears to be not likely, or those  not yet formed were impregnated
from the reservoir in the act of laying: for I conceived  that these
bags, by containing  semen, had a power of impregnating the egg as
it passed along to the anus, just as  it traversed the mouth of the duct
of communication.
  Finding that eggs completely formed  could  be  impregnated by
the semen, and also finding that the before-mentioned  bag was a re-
servoir for the semen till wanted,  I wished next to discover if they
could be impregnated from  the semen  of this bag; but as this must
be done without the act of copulation, I conceived it proper, first, to
see whether the ova of  insects  might  be impregnated without the
natural act of copulation, by applying the male semen  over the ova,
  * All these experiments on the silk-moth were begun in the summer 1767, and
repeated by Mr. Bell in the year 1770. 
452
HUNTER ON THE ANIMAL CECONOMY.
just as they were laid.  The  following experiments were made on
the silk-moth.
   Experiment I.  I took  a female  moth, as soon  as  she  escaped
from her pod, and kept  her carefully by herself upon a clean card,
till she began to lay ;  then I took males that were ready for copula-
tion, opened them, exposing their seminal ducts, and  after cutting
into these, collected their semen with a hair pencil: with this semen
I covered the ova, as soon as they passed out of the vagina.  The
card with these eggs, having a written  account of the experiment
upon it, I  kept in a box by itself.  In the ensuing  season  eight of
the ova hatched  at  the  same time with others naturally  impreg-
nated.   Thus then I ascertained that the eggs could be impregnated
by art, after they were laid.*
   The ova laid  by females that  had not been impregnated did not
stick where they were laid ;  so that the semen would appear not
only to  impregnate  the ova, but  also to  be the means  of attaching
them.
   To know whether that bag in the female silk-moth which increased
at the time of  copulation, was  filled with  the semen of the male,
I made the following experiment.
   Experiment II.  I took a female moth, as soon as she had escaped
from the pod, and kept her on a  card till she began to lay.  I then
took females that were fully impregnated before they began to lay,
and dissected out that bag which I supposed to be the  receptacle
for the male semen ; and wetting a camel-hair pencil with this mat-
ter, covered the  ova  as soon as they  passed  out of the vagina.
These ova were laid carefully on the clean card,  and kept till the
ensuing season, when they all hatched at the same time with those
naturally impregnated.
   This proves that this  bag  is  the  receptacle  for the semen, and
gradually decreases as the eggs are laid.

                    Of the Sting of the Bee.

   I have observed that it  is only the queen and the labourers that
have stings; and this provision of a  sting is perhaps as curious a
circumstance as  any attending the bee,  and probably  is one of the
characters of the bee tribe.
   The apparatus itself is ofa very curious construction, fitted for in-
flicting a wound, and at the same time conveying a poison into that
wound.  The apparatus consists of  two piercers, conducted in a
groove, or  director,  which appears  to  be  itself  the  sting.  This
groove is somewhat thick at its base, but terminates in a point; it
is  articulated to the  last scale  of the upper side of the  abdomen by
thirteen thin scales, six on  each  side, and one  behind the rectum.
These scales inclose, as  it  were, the rectum or anus  all round;
they can hardly  be  said to be articulated  to each other, only at-
  * [This circumstance was proved, as  regards the ova of fishes, by Gleditsch.
See M£moires de l'Acad. de Berlin, 1764.]                    J 
OBSERVATIONS ON BEES.
453
tached by thin membranes, which allow of a variety of motions;
three of them, however, are  attached  more closely to around and
curved process, which comes from the basis of the groove in which
the sting lies, as  also to the curved arms of the sting, which spread
out externally.   The two stings may be said to begin by those two
curved processes at their union with the scales, and converging
towards the groove at its base, which they enter, then pass  along it
to its point.   They are serrated on their outer edges, near to the
point.  These two strings can  be  thrust  out beyond the groove
although not  far, and they can be drawn within it; and, I  believe,
can be moved singly.  All these parts are moved by muscles, which
we may suppose are very strong in them, much stronger than in
other animals ; and these muscles give motion in almost all directions,
but  more particularly  outwards.   It is  wonderful how deep they
will pierce solid  bodies with the sting.  I have examined the length
they have pierced the palm  of the  hand, which  is covered with a
thick cuticle  : it  has often been about the Tyh of an inch.   To per-
form this by mere force two  things are necessary, power of muscles
and strength  of the sting, neither of which they seem to possess in
sufficient degree.  I own I  do  not  understand  this  operation.   I
am apt to conceive there is  something in it  distinct  from simple
force applied to  one end of a body ; for if this was simply the case,
the sting of the bee could  not  be made  to pierce by  any power
applied to its base, as the least  pressure bends it in  any direction ;
it is possible  the serrated edges may assist by cutting their way in,
like a  saw.
   The apparatus for the poison consists of two  small ducts, which
are the glands that secrete the poison : these two  lie in the abdomen,
among the air-cells, &c.: they both unite into one, which soon enters
into, or forms, an  oblong bag, like  a bladder of urine; at the oppo-
site end of which passes out a duct, which runs towards the angle
where the two stings meet;  and entering between the two stings,
is continued  between them in a  groove, which forms  a canal by the
union of the  two stings to this point.  There  is  another duct on the
right of that  described  above, which is not so  circumscribed, and
contains a thicker  matter, which, as far as I have been able to judge,
enters along  with  the other: but it is the first that contains the poi-
son, whichls a thin, clear fluid.   To ascertain which  was the
poison, I dipped points of needles  into both, and pricked the back
of the hand : and  those punctures  that had the fluid from  the first-
described bags in  them grew  sore and  inflamed, while the others
did  not.  From the stings  having serrated edges, it is seldom the
bees can disengage them;  and they  immediately upon  stinging
endeavour to make their escape, but are generally prevented, as it
were caught in  their own trap; and the force they  use commonly
drags  out the whole of the  apparatus for stinging, and also part  ot
the bowels;  so that the bee most frequently falls a sacrifice imme-
diately upon having effected its purpose.  Upon a superficial view
one  conceives that the  first intention of the bee  having a sting is 
454          HUNTER ON THE ANIMAL CECONOMY.
evident; one sees it has property to defend, and that therefore it is
fitted for defence : but why it  should  naturally fall a sacrifice in its
own defence, does not so readily appear: besides, all bees have stings,
although all bees have not property to  defend, and therefore  are
not under the same necessity of being so provided.  Probably its
having a sting to  use was sufficient for  nature to  defend the  bee
without using it  liberally ; and the loss of a bee or  two, when they
did sting, was of no consequence: for it is seldom that more die.
   I have now carried the operations of a hive, or the ceconomy of
the bee, completely round the  year ; in which time they revolve to
the first point we set out at, and the continuance is only a  repetition
of the same revolutions as I  have  now described:  but those revo-
lutions occasion  a series of effects in the  comb, which  effects in
time produce variations in the life of the hive.  Besides, there are
observations that have little to do  with the ceconomy of a year, but
include  the whole of the life of this insect, or at least its hive.

                     Of the Life  of the Bee.

   I have observed that the life of the male is only  one summer, or
rather a month or two ; and this we know from there  being  none
in the winter, otherwise their age could not be ascertained, as it is
impossible to learn the age of either the queen or labourers.   Some
suppose that it is the young bees which swarm ; and most probably
it is so: but I think it  is probable also, that  a certain  number of
young ones may be retained to keep  up the stock, as we must sup-
pose that many of the old ones are, from accidents of various kinds,
lost to the hive;  and we could conceive, that a hive three or four
years old  might not have an original bee in  it, although a  bee
might live twice that time.   But there must  be a  period for a bee
to live; and if I were  to judge from analogy, I should  say that a
bee's natural  life is limited to a certain number of seasons; viz.,
one bee does not live one year, another two, another three, &c.  I
even conceive that  no individual  insect of any  species  lives  one
month  longer than the others of the same  species.   I believe  this
is  the case with  all insects; but the age of either  a  labourer or a
queen may never be discovered.   One might suppose  that  the life
ofa bee, and the time a  hive can possibly last, would  be nearly
equal:  although  this is not  absolutely necessary, because they can
produce a succession, which they probably do; for I am very ready
to imagine, that after the first  brood in the season, all the last winter
bees die, and the hive is  occupied with the first brood ; and that
they breed the first swarm, or that the old breed the  whole of this
season's breeding, and then die, and those that continue through
the winter are the young, and if so, then they follow  the same
course with their progenitors.
   The comb of  a hive may be said to be the furniture and store-
house of the bees, which by use wear out;  and from  the descrip-
tion I have given, it will appear  that the  comb in  time  will be
rendered unfit for use.  I observed that they did not clean out the 
OBSERVATIONS ON BEES.
455
excrement of the maggot, and that the maggot, before it  moved
into the chrysalis state, lined the cell with  a silk, similar to many
other insects.  It lines the whole  cell, top, sides, and bottom; the
two last are permanent;  and at the bottom it covers with this lining
its own excrement.*   Why the bee maggot is formed to do this is
probably because honey  afterwards is to be put into the cell;  so
that the honey is laid  into this last silken bag.  How often they
may breed in the same cell I do not know, but I have known them
three times in  the same season; each time the excrement has been
accumulating,  and the cell has been lined  three times  with silk.
From this account we must  see that a  cell in time  will be so far
filled up  as to render it  unfit for breeding.  On  separating  the
lining of silk, which is easiest done at the bottom, on account of the
dried excrement between each lining, I have counted  above  twenty
different linings in one cell, and found the cell about one-quarter, or
one-third filled up ; when such a cell, or a piece of comb with such
cells, is steeped in  water, so as to soften the excrement between
the linings, they are separated from each other  at the bottom by
the swelling of the excrement, so that  they can be easily counted.
A piece of comb so circumstanced, when boiled  for the wax, will
keep its form,  and  the small  quantity of  wax is squeezed  out of
different parts  as if squeezed  out of a  sponge, and runs  together
into the crevices ; while a piece of comb, that never has been bred
in, even of the same  hive, melts almost  wholly down.  It is this
wax that has the fine  yellow, while the other  of the  same hives,
although brown, yet shall be white when melted; so that  I  was
led to imagine the  wax took its tinge from  the  farina, excrement,
&c, but  upon  boiling pure wax with  such materials it was not
tinged  with this  transparent  yellow, only became dirty.  In some
of those cells that had probably been bred in twenty times or more,
when soaked so as to make the excrement swell, I  have seen the
bottom of the last lining rise  even  with the  mouth,  or top of the
cell, so that the cavity of the cell was now full: in others,  I have
seen it rise higher than the mouth, so  that the last-formed  layers
were almost inverted, and turned inside out.   A piece of such comb,
consisting of two rows of cells, is to be considered as a mould, and
the lining of silk and the excrement as the cast; when this is  boiled,
so as either to extract all the  wax or mould, or to destroy its origi-
nal regular formation which  constituted the  comb, and nothing is
left but the cells of silk, &c, they  all  easily  separate from each
other, being only so many casts, with  the mould destroyed; and
the bottoms, which were indented into  each other, are very perfect.
  From the above account we must see that the combs ofa hive
can only last a certain number of years ; however, to make them
last longer, the bees often add a little to the mouth of the cell, which
is seldom done with wax alone, but with a mixture; and they some-
times cover  the silk lining of the last chrysalis ; but all this  makes
such cells clumsy, in comparison to the original ones.
  • This neither the wasp nor the hornet do, although they do not clean out the
excrement of their maggots. 
456          HUNTER ON THE ANIMAL CECONOMY.
   40. ANATOMICAL REMARKS ON  A NEW  MARINE
                          ANIMAL.*

   Animals which come from foreign conntries,  and  cannot be
brought to England alive, must be kept in spirits  to preserve them
from putrefaction, which makes them  less fitted for anatomical ex-
amination ; for  the spirits which preserve them produce a change
in many of their properties, and alter the natural colours and texture
of their parts, so that often the structure alone of the animal can be
ascertained; and  where this is  not naturally distinct it  becomes
frequently entirely obscured, and the  texture of the finer parts is
wholly  destroyed, requiring a very extensive knowledge of  such
parts in animals at large, to assist us in bringing them to light;  this
happens to be the  case with the animal whose dissection is the sub-
ject of this postscript.
   The  animal may  be said  to consist of a fleshy covering, a
stomach and intestinal  canal, and the two  cones with their  ten-
tacula   and moveable  shell, which  last may be considered as
appendages.
   The body of the animal is flattened, and terminates in two edges,
which  are intersected by rugae, the fasciculi of transverse muscular
fibres which run across the back being continued over them.  Upon
each of these edges is placed a row of fine hairs, which project to
some distance from the skin.
   The fleshy covering consists principally of muscular fibres: those
upon the back are placed transversely, to contract the  body later-
ally ;  those on the belly longitudinally, to shorten  the  animal when
stretched out, and to draw it into the  shell.
   The stomach and intestine make one straight canal: the anterior
end of this forms the mouth, which opens  into the grooves made
by the spiral turns of  the  tentacula  round  the  stem of each of
the cones; and  the intestine at the posterior end  opens externally,
forming the anus.   From the  contracted state of the animal the
intestine is thrown into a number of folds.
   On examining the cones and the tentacula I at  first believed that
the spiral form arose from their  being in a contracted state;  and
that when the tentacula were erected the cone untwisted, forming
a longer cone with the tentacula arising from its sides, like the plume

   * [This  animal was sent to Mr. Hunter from Barbadoesby Sir Everard (then
Mr.) Home, who described it in the Philosophical Transactions for 1784 as a
species of Actinia, and the anatomical remarks  in the text from the postscript
to that Paper.  The same species had been,  however, previously described and
figured by  Pallas in the Miscellanea Zoologica, p.  139, lab. x. fig. 2__10, (1766,)
and had been more correctly referred by that distinguished naturalist to t'he genus
Serpula, under the name of Serpula gigantea. It still retains this denomination,
and is placed among the tubicular Anellides in  the latest edition of the Regne
Animal of Cuvier.] 
ANATOMICAL REMARKS, ETC.
457
from the stem of a feather;  and that this  stem was drawn in or
shortened by means of a muscle passing along  the  centre, which
threw the tentacula into a  spiral line, similar to the penises of many
birds;  but how far this is  really the  case I have not  been  able to
ascertain.
  The internal structure of this animal,  like most of those  which
have tentacula, is very simple;  it differs, however, materially from
many,  in having an anus, most animals of this tribe, as the  polypi,
having only one opening, by which the  food is received, and the
excrementitious part of it also afterwards thrown out.*  This we
might have supposed, from analogy, to take place in  the  animal
which  is here described, more particularly  since it is inclosed in a
hard shell, at the  bottom of which there appears to be no  outlet;
but as  there is an anus this cannot  be the case.
  It is  very singular that in  the  leech,f  polypi, &c, where  no
apparent inconvenience can arise from having an anus, there is not
one ; while in this animal,  w'here it  would seem to be  attended with
many,  we find one ; but there being no anus in the polypi, &c, may
depend upon some circumstance in  the animal oeconomy which we
are at  present not fully acquainted with.
  The univalves, whose bodies are  under  similar  circumstances
respecting the shell with this animal, have  the intestine reflected
back, and the anus by that  means  brought near to  the external
opening of the shell, the  more readily to discharge the excrement;
and although this structure in  these animals appears to be solely
intended to answer that purpose, yet  when we find the same struc-
ture in the black snail, which has no shell, this  reasoning will not
wholly apply, and we must refer it to some other  intention in the
animal ceconomy.J
  In this animal we must therefore rest  satisfied that the disadvan-
tageous situation of the anus, with respect to the excrement's being
discharged from the shell,  answers  some purpose in the oeconomy
of the animal which more than counterbalances the inconveniences
produced  by it.
  It would appear, from considering  all  the circumstances, that the
excrement thrown out at the anus must  pass from the tail along the
inside of the tube, between it  and  the body of the animal,  till  it
comes to the external opening of the shell, as  there  is no other
evident mode of discharging it.
  How the tube 01 shell is formed in stone or coral is not easily
ascertained.   It may be asked  whether  this animal has the power
of boring  backwards, as  the  Teredo  navalis  probably  does, or
  * [This is not the case with those Polypi which have the tentacula beset with
vibratile cilia, as the Flustrx, Escharx, Vescularix, &c, as in these there is a re-
flected intestinal canal, terminating by a distinct anus, opening near the mouth.]
  \  [In the leech  the alimentary canal  terminates by a minute anus, situated
above the caudal sucker.]                                         ,
  X [The reflected disposition  of the intestinal  canal is, in a greater or less de-
gree, common to all molluscous animals, and the anus is thus brought into com-
munication with the respiratory cavity.]
                               40 
458
HUNTER ON THE ANIMAL CECONOMY.
whether the stone  or coral is formed  at the same time with the
animal, and grows and increases with it ; and if we consider all the
circumstances, this last would appear to be most probable, and agree
best with the different pheenomena; for the coral is lined with a  shell,
which could not be the case if the animal was continually increasing
this hole, both in length  and breadth, in proportion  to its growth;
but if the coral and  the  animal increase together, it is then similar
to the growth of all  shells, whether bivalve or univalve.
  The animal does not appear to  have the power of increasing its
canal, being only composed  of  soft parts.  This,  however is no
argument against its doing it, for  every shell-fish has the power of
removing a part of its shell, so as to adapt the new  and  the old
together, which is not done by any  mechanical power, but by ab-
sorption.*
  The tribe of animals which have  tentacula consists of an almost
infinite variety, and  many of  the  species have been  described.  Of
that kind, however,  which has the double cones, I believe hitherto
no account has been given.   It is most probably to be found in the
seas surrounding the different islands  in  the West Indies, for I re-
ceived  an animal some years  ago from  Mr. Oliver, surgeon,  at
Tenby  in Pembrokeshire, which  he had procured  from a gentle-
man  at St. Vincent's, which, upon  examination, proves to be the
same animal  with that  above described, only that the moveable
shell is wanting.
   Since I  began  this Postscript I  find  there is a description of a
double-coned  Terebella, published by  the  Rev. Mr.  Cordiner, at
Banff in Scotland, which was found upon that coast, in which the
cones  have their  tentacula  passing out  from  the  end, and  when
erected they spread  from  the  cone as  from a centre.   This proves
that the animals  with double-coned tentacula also have different
species.

  * [This is best illustrated in the thinning of the septa between the different
whorls of the cones and  olives.  If the margins of these septa be examined with
a pocket lens, after a section of the shell has been made, it will be found that
two out of the three layers of which they were originally composed have been
removed. The  absorption  of shell is also illustrated in  the removal  or  the
smoothing down of the spines of the Murices,- in the flattening of the inner lip
of the  mouth of the Purpurx,- in the widening of the faecal  aperture of the
Fissurellx, &c, &c.  These instances were doubtless well  known to Hunter;
but the doctrine of the absorption of  shell has been lately adduced as a new
discovery, in a  recent  volume of the Philosophical Transactions.  See  Mr. J.
 E. Gray "On the Power possessed by Mollusca of dissolving Shells."  Phil.
Trans. 1833, p. 796.] 
OBSERVATIONS  ON SOME  FOSSIL BONES.         459
41. OBSERVATIONS  ON  THE  FOSSIL BONES PRESENT-
     ED TO THE ROYAL SOCIETY BY HIS MOST SERENE
     HIGHNESS THE MARGRAVE  OF  ANSPACH, ETC.

               BY THE LATE  JOHN  HUNTER, ESQ., F.R.S.

               [Communicated by Everard Home, Esq., F.R.S.*]

   The bones which are the subject of the present paper are to be con-
sidered  more in the light of incrusted bodies than  extraneous fossils,

  * [From the Philosophical Transactions, vol. lxxxiv. ; read May 8th, 1794.
  The following description, by the Margrave of Anspach, of the caves from
which the fossils described in the text were taken, precedes the original memoir.
  "A ridge of primaeval  mountains runs almost through Germany, in a direction
nearly from west to east; the Hartz, the mountains of Thuringia, the Fichtel-
berg in Franconia, are different parts of it, which in their further extent consti-
tute the Riesenberg, and  join the Carpathian mountains.   The highest part of
this ridge are granite, and are flanked by alluvial and stratified  mountains, con-
sists chiefly of limestone, marl, and sandstone; such at least is the tract of hills
in which the caves  to be  spoken  of are  situated; and over these hills  the main
road leads from Bayruth to Erlang, or Nurenberg.  Half-way to this town lies
Streitburg, where there is a post, and  but  three or four  English  miles  distant
from thence are the caves mentioned, near Gailenreuth and Klausstein, two small
villages,  insignificant  in themselves,  but become famous  for the discoveries
made in their neighbourhood.
   "The tract of hills is there broken off by many  small and narrow valleys, con-
fined mostly  by steep and high rocks, here and there overhanging, and threaten-
ing, as it were, to fall  and crush all beneath; and everywhere thereabouts are
to be met with objects which  suggest the idea of their being evident vestiges of
some general and mighty catastrophe which happened in the primaeval times of
the globe.
   " The strata of these hills consist chiefly of limestone of various colour and tex-
ture, or of marl and sandstones.  The tract of limestone hills abounds with petri-
factions of various kinds.
   " The main entrance to the caves at Gailenreuth  opens near the summit of a
limestone hill towards the east.  An arch, near seven feet high, leads into a kind
of ante-chamber, eighty feet in length,  and three  hundred feet in circumference,
which constitutes the vestibule of four  other caves.  This ante-chamber is lofty
and airy, but has no light except what enters by its open arch ; its bottom is level,
and covered with black mould, although the common soil of the environs is loam
and marl.
  " By several circumstances, it appears that it has been  made use of in turbu-
lent times as a place of refuge.
   " From this vestibule, or first cave, a dark and  narrow alley opens in the  cor-
ner at the south end, and leads into the second cave, which  is about sixty feet
long, eighteen high, and  forty broad.  Its  sides and roefs  are covered, in a wild
and  rough manner, with stalactites, columns of which are hanging from the
roof, others rising from the bottom, meeting the first in many whimsical shapes.
   " The  air of this cave, as well as of all the rest, is always cool, and has, even
in the height of summer, been found below temperate.   Caution is therefore neces-
sary to its visiters; for it is remarkable that people, having spent any time in this or
the other caverns, always on their coming out again appear pale, which in  part
may be owing to the coolness of the air, and  in part likewise  to the particular
exhalations within  the caves.  A very narrow, winding, and troublesome pas-
sage opens  further into a                                         ,.
  " Third cave or chamber, of a roundish  form, and about thirty feet diameter 
460
HUNTER ON  THE ANIMAL CECONOMY.
since their external surface has only  acquired a covering of crys-
tallized earth, and little  or no change has  taken place in their in-
ternal  structure.

covered all over with stalactites.   Very near its entrance there is a perpendicular
descent of about twenty feet, into a dark and  frightful abyss ; a ladder must be
brought to descend into it, and caution is necessary in using it, on account of the
rough and slippery stalactites.  When you are down,  you enter into a gloomy
cave  of about fifteen feet diameter and thirty feet high, making properly but a
segment of the third  cave.
  " In the passage  to this  third cave, some teeth and  fragments  of bones are
found ;  but coming down to the pit of the cave, you are every way surrounded
by a vast heap of animal  remains.  The bottom of this cave .is paved with a
stalactical crust of near a foot in thickness;  large  and small fragments of all
sorts of bones are scattered  everywhere on the surface of the ground,  or easily
drawn out of the mouldering rubbish.  The very walls  seem filled  with various
and innumerable teeth and broken bones.  The stalactical covering of the uneven
sides  of the cave does not reach quite down to its bottom, whereby  it plainly ap-
pears that this vast collection  of  animal rubbish some time ago filled a higher
space in the cave, before  the bulk  of it sunk by mouldering.
  "This place is in appearance very  like a large quarry of sandstones ; and in-
deed  the largest and finest  blocks of osteolithical concretes might be hewn out
in any number, if there was  but room enough to come to them, and to carry them
out.   This bony rock  has been dug into in different  places, and  everywhere
undoubted proofs have been  met with, that its bed,  or this osteolithical stratum,
extends every  way far  beneath and through  the  limestone rock into which and
through which these caverns have been made;  so that the queries suggesting
themselves about the astonishing  numbers of animals  buried here confound all
speculation.
  "Along the sides of  this third cavern there are some narrower openings,
leading  into different smaller chambers, of which it cannot be said how deep
they go.   In  some  of them bones of  smaller animals have been found, such
as jaw-bones,  vertebrae, and  tibiae, in large heaps.  The bottom of this cave
slopes toward a passage seven feet high, and  about  as wide, being  the  entrance
to a
  " Fourth cave, twenty feet high and fifteen wide, lined all round with a stalac-
tical crust, and gradually sloping  to anether  deep descent, where the ladder is
wanted a second time,  and must be used with caution  as before, in order to get
into a cave forty feet high and about half as  wide.   In these deep  and  spacious
hollows, worked out through the  most  solid mass of rock, you again  perceive
with  astonishment immense numbers of bony fragments of all  kinds and sizes,
sticking everywhere in the  sides of the cave, or lying on the bottom.  This
cave also is surrounded by several smaller  ones;  in one of them rises a stalactite
of uncommon bigness, being  four feet  high  and eight feet diameter, in the form of
a truncated cone.  In another of those side grottos,  a very neat stalactical pillar
presents itself, five feet in height, and eight inches  in diameter.
  "The bottom of all these grottos is covered with true animal mould, out of
which may be drug fragments of bones.
  "Besides the smaller hollows, spoken of before, round this fourth cave, a very
narrow opening has been  discovered in one of its  corners.   It is of very difficult
access, as it can be entered  only in a  crawling posture.  This dismal and  dan-
gerous passage leads into a fifth  cave, of near thirty feet high, forty-three long, and
of unequal breadth.   To the depth  of six feet this cave has been dug, and nothing
has been found but fragments of bones  and animal mould.   The sides are finely
decorated with stalactites of different forms and colours ; but even this stalactical
crust is filled with fragments of bones sticking in  it, up  to the very  roof.
  " From this remarkable cave another very low and  narrow avenue leads into
the last discovered, or the
  " Sixth cave, not  very large, and  merely covered with  a stalactical crust, 
OBSERVATIONS ON SOME FOSSIL BONES.         461
  The earths with which bones are most commonly incrusted  are
the calcareous, argillaceous, and siliceous, but principally the  cal-
careous ; and this happens in two ways:  one, the bones being im-
mersed in water in which this earth is suspended ; the other, water
passing through masses of this earth,  which it dissolves, and after-
wards deposits  upon bones which lie underneath.
  Bones which are incrusted seem never to undergo this change in
the earth, or under the water, where  the soft parts were destroyed;
while bones that are fossilized become so in the medium  in which
they were deposited* at the animal's death.   The incrusted bones
have been previously exposed to the open air: this is evidently the
case with the  bones at present under  consideration,  those of the
rock  of Gibraltar,  and  those  found in Dalmatia; and, from the
account given by the Abbe Spallanzani, those of the island of Cerigo
are under the same circumstances.  They have the characters of
exposed bones, and many of them are cracked in a number of places,
particularly the cylindrical bones, similar to the effects of long ex-
posure to the sun.   This circumstance appears to distinguish them
from fossilized  bones,  and gives us  some information  respecting
their history.
   If their numbers had  corresponded with what we  meet  with of
recent bones, we might have been led to some  opinion of their mode
of accumulation ; but the quantity exceeds anything we  can form
an idea of.  In an inquiry into their history three questions naturally
arise: Did the  animals come there and die?  or, Were their bodies
brought there, and lay exposed? or, Were the bones collected from
different places?  The first of  these conjectures appears to me the
most  natural; but yet  I am by no means convinced of its being the
true one.
   Bones of this description are  found  in very different  situations,
which  makes  their  present  state more difficultly accounted  for.
Those in Germany are found in caves; the  coast of Dalmatia is
said to be almost wholly formed of them ; and we know that this is
the case with a large portion of the rock of Gibraltar.
   If none were found in  caves, but  in solid  masses covered with
marl  or limestone, it would then give the idea of their having been
brought together by some strange cause, as  a  convulsion in the
earth, which threw  these  materials over them ;  but  this  we can
hardly form an idea of.  Or if they had  all been found in caves, we
should  have imagined these caves were places of retreat for  such

in which, however, here and there bones are seen sticking. And here ends this
connected series of most remarkable  osteolithical caverns, as far as they have
been hitherto explored ;  many more may for what we know exist, hidden,  in the
same tract of hills.
  " Mr. Esper has written a  history in German of these caves ;  and  given
descriptions and plates  of  a  great number of the fossil bones which have been
found there.  To this work we must refer for a more particular account of them.  ]
  * Bones that have been buried with the flesh on acquire a strain which they
never lose, and those which have been long immersed in water receive a consider-
able tinge.
                              40* 
462
HUNTER ON THE ANIMAL  CECONOMY.
animals, and had been so for some thousands of years; and if ^e
bones were those of carnivorous animals and herbivorous, we might
have supposed that the carnivorous had brought in many animals
of a smaller size which they caught for food.   And this, upon the
first view, appears to have been the case with those which are the
subject  of this paper; yet when we  consider  that the  bones are
principally of carnivorous animals, we  are confined to the supposi-
tion of their being only places of retreat.   If they had been brought
together by any convulsion of the earth, they would have  been
mixed with the surrounding materials of the mountains, which does
not appear to be the case; for although some  are found  sticking
in the sides of the caves incrusted in calcareous  matter, this seems
to have arisen from  their  situation to the cave.  Such accumu-
lation would have made them coeval with the mountains them-
selves, which from the recent state of the bones I should very much
doubt.
   The difference in the state of the bones shows that there was pro-
bably a succession of them for a vast series of years; for if we con-
sider the distance of time between the most perfect having been de-
posited, which we must suppose were the last, and the  present time,
we must consider it to be many thousand  years.  And if we calcu-
late how long these must still remain to be as far decayed as some
others are, it will  require  many thousand years, a sufficient time
for a vast accumulation.   From this mode of reasoning, therefore,
it would appear that they were not brought here at once in a recent
state.
   The animal earth, as it is called, at the bottom of these caves, is
supposed to be produced  by the rotting of the flesh, which is sup-
posing the animals brought there with the flesh on; but I do con-
ceive that, if the caves had been stuffed with whole animals, the
flesh could not have produced one-tenth part  of the earth; and, to
account for such a quantity as appears to be the produce of animals,
I should suppose it the remains of the dung of animals who inhabit-
ed the caves, and the contents of the bowels of those they lived upon.
This is  easily conceived from knowing that there is something simi-
lar to it, in a smaller  degree, in many caves in this kingdom, which
are places of retreat for bats in the winter, and even in the summer,
as they only go abroad in the evenings.  These caves have their
bottoms covered with animal earth, for some feet in depth,  in all
degrees of decomposition, the lowermost the most pure, and the up-
permost but little  changed, with  all the  intermediate degrees;  in
which caves are formed a vast number of stalactites,  which might
incrust the bones of those that die there.*

  * [Hunter probably little suspected that there were caves in this kingdom, like
those of  Germany, abounding with the  remains of extinct mammalia.  These
caves, especially that of  Kirkdale in Yorkshire, and  the fossils discovered in
them, are admirably described in the 'Reliquiae Diluvianae' of Dr. Buckland ;
and it is gratifying  to find that the conclusion which Hunter adopted, out of the
different hypotheses which he suggests to account for  the presence of the bears'
bones in  the Bayreuth caverns, viz., that these had served as an habitual retreat 
OBSERVATIONS ON SOME FOSSIL BONES.         463
  The bones in the caves in Germany are so much the object of
the curious that the specimens are dispersed throughout Europe,
which prevent a sufficient number coming  into the hands of any
one person to make him acquainted with the animals to which they
belong.
  From the history and figures given by Esper it appears that there
are the bones of several  animals; but what  is curious, they all ap-
pear to have been  carnivorous, which we should not have expected.
There are teeth, in number, kind, and mode of setting, exactly simi-
lar to the white bear, others more like  those of the lion ;  but the
representations of  parts, however well executed, are  hardly to be
trusted to for the nicer characters, and much less so when the parts
are mutilated.*
  The bones sent by his  Highness the Margrave of Anspach agree
with those described and delineated  by  Esper as belonging to the
white bear; how far they are of the same species among themselves
I cannot say.   The heads differ in shape from  each other;  they
are, upon the whole, much longer for their breadth  than  in  any
canivorous animal  I know  of:  they also differ from the present
white bear, which, as far as I  have seen, has a common propor-
tional breadth.   It is supposed, indeed, that the heads of the present
white bear differ from one another;  but the truth  of this assertion
I have not seen heads enough of that  animal to determine.
  The heads not only vary in shape but also in size ; for some of
them, when  compared with the recent  white bear, would seem to
have belonged to an animal twice its size : while some of the bones
correspond in size with those of the white bear, and  others are even
smaller.f
  There are two ossa  humeri, rather of a less size than those of
the recent white bear ; a first vertebra, rather smaller;  the teeth also
vary considerably  in size, yet they are all those of the same tribe ;
so that the variety among themselves  is not less than between them
and the recent.
  In the formation of the  head, age  makes a considerable differ-
ence : the skull of  a young dog  is much more rounded than an old
one ; the ridge leading back  to the occiput, terminating in the two
lateral ones, hardly exists in a young dog; and among the present
bones there is the back part of such a  head, yet it is larger than the
to the living animals, and had thus become the depository of the remains of
successive generations, agrees with the theory proposed by  Dr. Buckland with
reference to the bones of the hyaenas, accumulated at Kirkdale, the chief argu-
ment in support of which is derived from the abundance of earthy or bony dung
with which the fossils are associated.]
  * [Remains of an indubitably large feline animal have been found associated
with the bears' bones in the Bayreuth and Gaybureuth caverns.  The mutilated
cranium figured by Leibnitz  in his Protogaea, PI. XL, is considered by Soem-
mering to have belonged to a lion.]
  f It is to be understood that the bones of the white bear that I have, belonged
to one that had been a show,  and had not grown to the full or natural size; and
I make allowance for this in my assertion that the heads of those incrusted appear
to belong to an animal twice the size of our  white bear. 
464           HUNTER ON THE ANIMAL  CECONOMY.
head of the largest mastiff;  how far  the  young  white bear may-
vary from the old, similar to the young dog, I do  not know, but it
is very probable.*
  Bones  of animals  under  circumstances  so  similar, although in
different parts of the  globe, one  would have  naturally supposed to
consist chiefly of those of one class or order  in  every  place, one
principle  acting in all places.f  In Gibraltar they are mostly of the
ruminating tribe, of the hare Idnd, and the bones of birds; yet there
are some of a  small  dog  or fox, and likewise  shells.   Those in
Dalmatia appear to be  mostly of the  ruminating  tribe; yet I saw
a part of the os hyoides of a horse;  but those  from  Germany are
mostly carnivorous.  From  these facts we should  be  inclined to
suppose that their  accumulation  did not arise  from any instinctive
mode of living, as the same  mode could not suit both carnivorous
and  herbivorous animals.J
  In considering animals respecting their  situation upon the globe,
there are many which are  peculiar to particular climates, and others
that are less confined, as  herrings, mackerel,  and salmon ;  others
again which probably move over the  whole  extent  of  the  sea, as
the shark, porpus,  and whale tribe ; while many shellfish must be
confined to one spot.§  If the sea had not shifted its situation more
than once, and was to leave the land in a very short time, then we
could determine what the  climate had formerly been by the  extra-
neous fossils of the  stationary  animals, for those only would be
found mixed with  those of passage;  but if the sea moves from one
place to another slowly, then the  remains of  animals of  different
climates may  be mixed, by those of one climate moving over those
of another, dying,  and being fossilized; but this I  am afraid cannot
  * [There are now skulls of the young and  old white bear in the  Collection of
the College of Surgeons in London which confirm Hunter's conjecture respecting
the difference of  form which is due to age in this  genus.  It will be seen that
Hunter adduces  this circumstance merely as one which must be taken into consi-
deration in comparing recent and fossil crania of the same genus; and that he by
no means asserts, as Cuvier states he does, that the differences which he had
detected between the fossil  and recent skulls, and  between the different fossil
skulls of the cave bears, are of the same nature and degree.—Ossemens Fossiles,
6me  Ed., torn, vii., p. 236.
  f [This sagacious conjecture has received remarkable confirmation from recent
discoveries ; the fossil bones that have  been found in Australia appertain for the
most part to animals of the marsupial order, and those collected in South America
contain a remarkable proportion of Edentata, some of  them of gigantic propor-
tions, but all protected by a bony armour analogous  to that of the armadillos,
which are peculiar to South America.]
  X [Mr. Lyell thus describes some of the circumstances under which the bones
of animals are accumulated at Gibraltar: " At the  north extremity of  the rock
are perpendicular fissures, on the  ledges of which a number of hawks nestle and
rear their young in the breeding season.  They throw down from their nests
the bones of small birds, mice, and other animals, on which they feed, and these
are  gradually united  into a breccia of angular fragments of the  decomposing
limestone with a  cement of red earth."   (Principles of Geology, vol. iii., p. 158.")
  § [For a full development of  the relation which the geographical distribution
of animals bears to the science of Oryctolosry, or Fossil Remains, the reader is
referred to the second  and third volumes of Lyell's Principles of Geology ] 
OBSERVATIONS  ON SOME FOSSIL BONES.         465
be made out.   By the  fossils we may, however, have some idea
how the bones  of the land animals fossilized may  be  disposed with
respect to those of the sea.
  If the sea should have occupied any space  that never  had been
dry land prior  to the sea's being there, the extraneous fossils can
only be those of sea  animals ;  but each  part will have its particular
kind of those that are stationary mixed with a few of the amphibia,
and of sea  birds, in those parts that were the  skirts of the sea.   I
shall suppose that when the sea left its  place  it  moved  over land
where both vegetables and land animals had  existed, the  bones of
which wall be fossilized, as also those of the sea animals; and if the
sea continued long here, which there is  reason to believe, then those
mixed extraneous fossils will be covered with  those of sea animals.
Now if the sea should again move, and abandon this  situation, then
we should  find  the land and sea fossils above  mentioned disposed in
this  order; and as  we begin  to  discover extraneous fossils in a
contrary direction to their formation, we shall first find a stratum
of those of animals peculiar to the sea,  which were the last formed,
and  under  it one of vegetables and land  animals, which were there
before they were covered by the sea, and among  them those of the
sea, and under this the  common earth.   Those peculiar to the  sea
will  be in depth in proportion to the time of the sea's residence and
other circumstances, as currents, tides, &c.
   From a succession of such shiftings of the situations of the  sea
we may have a stratum of marine extraneous fossils, one of earth,
mixed probably with vegetables and bones of land animals, a stratum of
terrestrial  extraneous fossils, then one of marine productions;  but
from the sea carrying its inhabitants along with it, wherever there
are  those of  land" animals there will also be a mixture of marine
ones ; and from the  sea commonly remaining  thousands of years in
nearly  the same situation, we  have  marine  fossils unmixed with
any others.*
   All operations respecting the growth or decomposition of animal
and vegetable substances go on more readily  on the  surface of the
earth than in it; the air is most  probably the great  agent  in de-
composition  and  combination,  and also a certain degree of heat.
Thus the  deeper we go into the earth  we find the fewer changes
going on ; and there is probably a certain depth  where no change
of any kind can possibly take place.  The operation of vegetation
will  not go  on at a  certain  depth,  but at this  very depth a
decomposition  can take place, for the seed dies and in time decays;
but  at  a still greater  depth the seed  retains its  life for  ages,  and

   * [The importance of the study of fossil remains in the elucidation  °f the nature
of the changes to which the earth's surface has been subject, here dwel  upon^by
Hunter, was placed in a strong light by the subsequent parches of C»vier a"J
Brogniart on the structure of the Paris Basin, and the fossils which have ren.ered
it so famous. By the aid of these fossils Cuvier was ^^^^fo-8"".
cession of strata  to several distinct alternations of marine and freshwater forma-
tions.] 
466          HUNTER ON THE ANIMAL CECONOMY.
when brought near  enough to the surface for vegetation it grows.
Something similar to this takes  place with respect  to extraneous
fossils;  for although a  piece  of wood or bone is dead when so
situated as to be fossilized, yet they are sound and  free from decompo-
sition, and the depth, joined  with the matter  in which they are
often found, as stone, clay, &c,  preserves them from putrefaction,
and their  dissolution requires thousands  of  years to complete it;
probably they may be under the same circumstances as in a vacuum ;
the heat in such situations is uniform, probably in common about 52°
or 53°, and in the colder regions they are still longer preserved.
  I believe it is generally understood that in extraneous fossils the
animal part is destroyed, but  I find that this is not the case in any I
have met  with.
  Shells, and bones of fish,most probably have the least in quantity,
having been longest in that state ; otherwise they  should have the
most;  for the harder and more compact the earth, the better is the
animal part preserved, which is an argument in proof of their having
been the longest in a fossil state.   From  experiment and observa-
tion  the animal part is not allowed to  putrefy ; it appears  only to
be dissolved into a kind of mucus, and can  be discovered  by dis-
solving  the  earth in an  acid :  when a shell is treated in this way
the animal substance is not fibrous or laminated, as in the recent
shell, but  without tenacity, and can be washed off like wet dust; in
some, however, it has a  slight appearance of flakes.
  In the shark's  tooth, or glosso-petra, the enamel is composed of
animal substance and calcareous earth, and  is  nearly in the same
quantity as in the recent; but the central part of the tooth has its
animal substance in the  state  of mucus interspersed in the calcare-
ous matter.
  In the fossil bones of sea animals, as the vertebras  of the whale,
the animal  part is  in large  quantity, and in  two states, the  one
having some tenacity, but the other  like wet dust; but in some of
the harder bones it is more firm.  In the fossil  bones of land  ani-
mals, and those which inhabit the waters, as the  sea-horse, otter,
crocodile, and turtle, the  animal part is  in considerable quantity.
In the stags' horns dug up in  Great Britain and Ireland, when the
earth is dissolved, the animal  part is in considerable  quantity, and
very firm.   The same observations apply to  the fossil bones of the
elephant found in England, Siberia, and  other  parts of the globe;
also  those of the ox kind;  but more particularly to  their teeth,
especially those from the lakes in America, in which  the  animal
part  has suffered very little;  the inhabitants find little difference
in the ivory of such tusks  from the recent, but its having a yellow
stain ; the cold may probably assist in their preservation.
  The state of preservation will vary according to the substance in
which they have been preserved ;  in peat and clay I think the most;
however,  there appears in general a species  of  dissolution, for the
animal  substance, although tolerably firm, in a heat  a little  above
100° becomes a thickish mucus, like dissolved gum, while a portion
from the external surface is reduced to the state of wet dust. 
OBSERVATIONS ON SOME FOSSIL BONES.
467
   In mcrusted bones the quantity of animal substance is very dif-
lerent  in  different  bones.  In  those from Gibraltar  there is very
little ; it in part retains its tenacity, and is transparent, but the super-
ficial part dissolves into mucus.
   Those from Dalmatia give similar results when examined in this
way.

   Those from Germany, especially the harder  bones and  teeth,
seem to contain  all the animal  substance  natural to them ;  they
differ, however, among themselves in this respect.
   The bones of land animals have their calcareous earth united with
the phosphoric acid instead of  the aerial,* and I believe retain it
when fossilized, nearly in proportion to the quantity of animal matter
they contain.
   The mode by  which I  judge of this  is by the quantity of  effer-
vescence ; when fossil bones are put into the muriatic acid it is not
nearly so great as when a shell is put into it, but it is more in some,
although not in all, than when a recent bone is treated in  this  way,
and this I think diminishes in proportion to the quantity of animal
substance they retain ; as a proof of this, those fossil  bones which
contain a small portion of  animal  matter produce in an acid the
greatest effervescence when the surface is acted on, and  very little
when the centre is affected  by it; however, this may  be accounted
for by the parts which have lost their phosphoric acid, and acquired
the aerial, being  easiest of  solution  in  the marine acid, and there-
fore dissolved first, and the  aerial acid let loose.
   In some bones of the whale the effervescence  is very  great; in
the Dalmatia and Gibraltar bones it is less; and in those the subject
of the present paper it  is  very little, since they contain by much the
largest proportion of animal substance, f

   * [Carbonic]
   X [In this Paper  we may perceive that Hunter appreciated the value  of the
study of Fossil Remains, and  their application to the elucidation of many im-
portant subjects.  First, with  reference to the extension of our ideas respecting
the zoology of this planet, we find him comparing the fossils which are the sub-
ject of the text, with their recent analogues, and he shows that they differ both
from them and among themselves : his observations and comparisons are, it is
true, too general and summary, and it was left  to his  successors in this field of
inquiry to pursue the comparison with the requisite minuteness and precision,
and to give names to the distinct but extinct species.  Hunter next briefly alludes
to the different situations and  climates  in the globe, to which animals'are more
or less confined ; and this subject, or the  geographical distribution  of animals,
considered in relation to fossil remains, elucidates,  amongst other interesting
questions, the  changes of temperature to which different parts of the earth have
been subject at different epochs.  Hunter points out more distinctly, and with
more detail, the evidence which extraneous fossils afford respecting the alterna-
tions of land and sea, of which the earth's surface has been the theatre; and by
his frequent allusion  to the " many thousand years "  which must have elapsed
during these periods, seems to have fully appreciated the necessity of an  ample
allowance of past time in  order to account philosophically for  the changes in
question.  Lastly, he treats of the nature and causes of the different states in
which  the remains of extinct animals are found ;  and  many of the fossil  bones
which were the subject of his chemical experiments  are still preserved in his
museum (see Nos. 118-130, Physiological Series.)
   When we turn from  the perusal of this  highly philosophical  memoir to the 
468           HUNTER ON THE  ANIMAL CECONOMY.
42.  DESCRIPTIONS  OF SOME  ANIMALS   FROM  NEW
                        SOUTH WALES.
                      BY  JOHN HUNTER, F.R.S.
   [The following descriptions are  interesting, not less from being
the  first that appeared of some of the most singular of the  qua-
drupeds which  characterize the Fauna of Australia, than from the
celebrity of  their  author,  of  whose  contributions  to  descriptive
zoology they are almost the  only examples.   They form  part of
the zoological appendix  to  a  "Journal of a voyage to  New South
Wales, 4to. 1790," published by John White, Esq., Surgeon-General
to the settlement, who thus acknowledges the assistance which he
derived from the gentlemen by whose cooperation he was " enabled
to surmount those difficulties that necessarily attended the descrip-
tion of so great a variety of animals,  presented for the  first time to
the observation of the naturalist, and  consequently in the class of
nondescripts.   Among those gentlemen he has  the honour particu-
larly to reckon  the names of  Dr. Shaw, Dr.  Smith, the possessor
of  the  celebrated  Linnsean Collection;  and  John  Hunter,  Esq.,
who to a sublime and inventive genius, happily unites  a disinterested
and generous zeal for the promotion of natural science."
   Dr. Shaw, who superintended  the publication of White's Zoolo-
gical Appendix, thus  introduces  the  observations  contributed by
Hunter:—
   " The nondescript animals of New South Wales  occupied a great
deal of Mr.  White's attention, and he preserved several specimens
of them in spirits, which arrived in England in a very perfect state.
There was no person to whom these  could be given with so  much
propriety as Mr. Hunter, he, perhaps, being most capable of ex-

notice of it in the Ossemens Fossils of Cuvier, we must suppose that it could have
been but very imperfectly known to the great founder of oryctological science.
In the chapter on  the  'Ours Fossiles,'Cuvier says: " Le celebre chirurgeon
anglais, J. Hunter, dans un Memoire sur les os fossiles, qui n'a que leur analyse
chimique pour  objet, et qui est insere dans  les Transactions Philosophiques,
donne deux belles  figures de cranes d'ours fossiles les meillures qui aient paru
jusque la, mais sans description  detaill£e, et en disant pour toute comparaison
que les differentes tetes d'ours de cavernes different autant  entre elles qu'elles
different de Pourspolaire, et que toutes ces differences ne surpassent point celles
que Page peut produire dans les animaux carnassiers ; assertion vague et meme
erronee."—Loc. cit., p. 237.
  A careful and  candid  perusal of Hunter's Memoir would doubtless have
exonerated the author from this charge  in the mind of Cuvier, as it must do in
that of every unprejudiced reader.  But it would  still afford a very inadequate
notion of the extent to  which Hunter had pursued his study of fossil remains.
The interest that he took  in them is shown by the frequent exhortations towards
their collection in  his letters to Jenner, and his collection at his decease included
about 1050 specimens, of which there are 259 belonging to the vertebrate classes
 including 70  specimens of fossil fishes, and 40  of reptiles), 116 cephalopods,
lib  univalves, 143 bivalves, 35 Crustacea, 163 echinodermata, 109 zoophytes,
and 50 fossil vegetable productions.]                               r J 
DESCRIPTIONS OF SOME ANIMALS,  ETC.
469
amining accurately their structure, and making  out their place in
the scale of animals;  and it is to him that we are indebted for the
following observations upon them, in which the anatomical structure
is purposely avoided, as being little calculated for the generality of
readers of a work of this kind."]

  It is much to be wished that those gentlemen who are desirous
of obliging their friends, and promoting the study of natural history,
by  sending home  specimens, would  endeavour  to  procure  all the
information they can relating to such  specimens as they-may collect,
more especially animals.
   The subjects themselves may be valuable, and may partly explain
their connection with those related to  them, so as in some measure to
establish their place in nature,* but they cannot do it entirely ; they
only give us the form  and construction, but leave  us in other re-
spects to conjecture,  many of them  requiring further observation
relative  to  their ceconomy.
   A neglect in procuring this information has left us almost to this
day  very ignorant of that part of the  natural  history of  animals
which is the most interesting.   The  Opossum is a  remarkable in-
stance of this.   There is  something  in the mode of propagation in
this animal, that deviates from  all others; and although known in
some degree to be  extraordinary, yet it has never been attempted,
where opportunity offered, to  complete  the investigation.   I  have
often endeavoured  to breed  them  in England; I have bought a
great many, and my friends have assisted me by bringing them or
sending  them alive, yet never could get them to breed ; and although
possessed of  a great  many facts respecting them, I do not  believe
my information is sufficient to complete  the system of  propagation
in  this class.f

  * [It is interesting to meet with these indications of the spirit in which Hunter
prosecuted his zoological researches.  To ascertain the affinities of the animals
whose structure he explored, or, in other words, to establish a natural system of
classification, was not  less the aim of Hunter than the determination of the
functions of the different organs in the animal frame ; and  the truth of the remark
of  the necessity of combining observation of the living habits of animals, with
anatomical and zoological research, in order to establish entirely their place
in  nature, as well as to  fully  understand  their ceconomy, is now universally
admitted.]
  f [Since the time of Mr. Hunter, the kangaroo by breeding in this country has
afforded the opportunity of elucidating many  of the peculiarities of the generative
ceconomy of  the Marsupial quadrupeds.  These peculiarities are not confined to
the female.  In the male, the testicles are situated in an exte rnal fold of the in-
tegument, corresponding in situation  to  the internal fold which constitutes the
marsupial pouch  in the female, and the scrotum thus formed is consequently
anterior to the penis.  The cremaster muscles wind round  the supplementary
bones attached to the pubis, which act as fulcra to the muscles, and enable them
to compress the gland with a force which seems to be demanded in consequence
of the tortuosity of the double vagina along which the semen has to be propelled.
The coitus is of long duration in the kangaroo, and the scrotum disappear during
the forcible retraction of the testes against the marsupial bones.
  The female kangaroo is pregnant for the space of thirty-eight days,  when
uterine birth takes place, and  the  embryo, now about  an  inch in length, is
                                 41 
170
HUNTER ON  THE ANIMAL CECONOMY.
   In collecting animals, even  the name  given  by the  natives if
possible should be known, for a name to a  naturalist should mean
nothing but that to which it is annexed,  having no  allusion to any-
thing else, for when  it  has  it  divides the  idea.  This observation
applies  particularly to  the   animals which  have come from  New

transferred, I suspect, by  the mouth of the parent, from the vulva to the nipple,
where it hangs, protected and concealed by the  pouch for about six months.
  Only two opportunities have as yet occurred for the examination of the uterine
fcetus.   These show that it  is nourished chiefly by  means of omphalo-mesenteric
vessels, which ramify over a large  vitelline sac.  When the extremities  are
formed, and the uterine fcetus has attained about two-thirds its size as such, an
allantois is developed ; the umbilical  arteries coextended with this  sac do not,
however, as in the placental mammalia, pass to the chorion ; but this membrane
continues unorganized, as in the ovoviviparous and oviparous classes, and con-
sequently there is no adhesion of the foetal  membranes to the uterine parietes,
and therefore no obstruction to the escape of the embryo (at the premature period
destined for its birth) from the uterus into the vagina.
   The uterus  is double in all the marsupiata,  and each cavity is of small size,
and ofa simple elongated form.  In the Didelphis dorsigera, each os tincae opens
into a long vagina, which makes a sweep outwards, and then converging towards
its fellow, opens into the upper end  of a cloacal passage, common to the two
vaginas and the urethra.   In the Virginian opossum, each vagina, before describ-
ing the outward curvature, sends down  a cul-de-sac, which is closely united to
the one on  the opposite side, but the cavities are distinct.   In the kangaroo,  the
two cul-de-sacs are blended together, so that the vagina communicate together
uoth at their commencement, and also at  their  termination in the meatus com-
munis.  The size of the vaginal cul-de-sacs seems to be in the ratio of the capacity
of the external pouch.
  The embryo is adapted  to its intra-marsupial existence by a precocious develop-
ment of the respiratory and  circulating organs, by a peculiar tubular form of the
mouth, and a grooved  tongue calculated to retain a firm hold on  the  elongated
nipple; it has also a peculiar construction of the larynx, somewhat analogous to
that of the whale, by which respiration may be  safely continued  in  the fcetus
while the mother injects  the milk down its  pharynx.   It would seem that the
new-born marsupial is incompetent  from its feeble and incomplete structure to
the office of forcing a stream of milk through the long and  tortuous lacteal ducts,
since the mammary gland is embraced  by a muscle, corresponding to the cre-
master in the male, and winding in a similar manner round the marsupial bones ;
these therefore aid the  expulsion of  the milk  in  the female, as they  do that of
the semen in the male ; they also in the female add to the power of the  mammary
muscles in sustaining a portion  of the weight of the foetus which is attached to
the nipple.
   Many have been the conjectures respecting the final intention of the  premature
birth of the marsupial animal, and of the various singular  modifications of struc-
ture  necessitated by, and adapted to that  circumstance.  Since it obtains in
quadrupeds of almost every variety of form, and with various modes of locomotion
and diversity of diet, it must result from some more general law than  individual
proportions or habits of the parent.   It is associated with a marked inferiority of
cerebral organization ; but the final purpose \yill be most probably discovered to
relate to some peculiarity in the physical  geography of that portion of the  globe
in which the quadrupeds almost  exclusively exhibit the marsupial organization.
Long-continued droughts and a scarcity of fresh water streams are amongst the most
striking features of the climate and territory of Australia; and when we°reflect that
the principal exceptions to  the marsupial organization,  viz., the Ornithorhynchus
and  the Hydromys, or water-rat of the colonists, habitually inhabit the freshwater
ponds, the peculiarities of  the reproduction above described may have reference
to the great distances which the mammalia of New South Wales are generally
compelled to traverse in order to quench their thirst.] 
DESCRIPTIONS  OF  SOME ANIMALS, ETC.          471
Holland; they are, upon the whole, like no other that we yet know
of,  but as they have parts in some respects similar to others, names
will naturally be given  to them  expressive of those  similarities,
which  has  already taken  place;  for  instance, one is  called the
kangaroo rat, but which should  not  be called  either kangaroo or
rat;  I have therefore adopted  such  names as can only be appro-
priated to each particular animal,  conveying no other idea.*
  Anirnals admit of being divided into great classes, but will not
so  distinctly  admit of  subdivision without  interfering with  each
other.   Thus the  class  called  quadrupeds is  so well marked that
even the whole is  justly placed  in  the same class, birds the same,
amphibia (as  they  are called) the  same, and so of  fishes, &c.; but
when we are subdividing these great classes  into  their  different
tribes, genera and  species, then we  find  a  mixture of properties,


  * [The evils  of  implying false affinities and of suppressing differences of pri-
 mary importance, which would have resulted from referring the newly discovered
 quadrupeds of Australia to  the known Linnaean genera, as was afterwards done
 by Dr. Shaw, were sagaciously avoided by Hunter.  And had the same expanded
 views been taken  by his colleague, zoology would not at the present time have
 been burdened with such  useless synonyms as  Didelphys  pelaurus, Didelphys
 penicillata, Didelphys viverrina, Didelphys obesula, &c, and the zoologists of the
 continent might have been spared the task of rectifying the errors of that arrange-
 ment, which  arising  from  an ignorance of the  anatomical distinctions of the
 animals in question, and from a disregard of the modifications presented by their
 teeth  and  locomotive  extremities, consisted  in  grouping  with the American
 opossums  the  species above quoted,—species which now form respectively the
 types of the genera Petaurus, Phascogale,  Dasyurus and  Perameles. Hunter,
 on the contrary, adopted the more natural and philosophical method of accurately
 pointing out  the differences and resemblances of each species, retaining for them,
 like Adan3on with reference to  the  nondescripts of Senegal, the native names,
 instead of applying to them Linnsean generic appellatives, which could only
 serve to propagate erroneous ideas of the objects to which  they were attached.
 These reflections are  so  obviously suggested by the text, that the following is
 offered as an  apology for their insertion: the  writer of a volume entitled a
 " Discourse  on the  Study of Natural  History," which by  some unfortunate
 casualty has appeared in the same series of publications as  that which contains
 Herschel's admirable Discourse on Natural Philosophy, introduces the name of
 John Hunter in his account of the naturalists who have contributed to the rise
 and progress of zoology for the sole purpose of instituting a disparaging compari-
 son between that great and original thinker and the author of  the General Zoology.
 " Dr. Shaw," Mr. Swainson observes, " was unquestionably the writer of nearly
 all the zoological descriptions in White's Voyage to New South Wales, whereas
 he (John Hunter) merely wrote the  account of five of the quadrupeds and these
 are neither named nor scientifically  characterized."
    Now the  fact  is that Hunter's  descriptions of the parts best adapted for
 zoological characters are so exact and so minute  that a zoologist has no difficulty
 in assigning the species to the most recent  zoological subdivisions, as any one
 may convince  himself who compares the  account of the   Tapao Tafa with the
 characters assigned  by Temminck to his genus  Phascogale.  But Hunter added
 also observations  on the differences  and peculiarities of the internal structure of
 the  marsupial quadrupeds, yet Dr. Shaw was so blind   to the true methods
 of advancing the science of zoology, and so little able to appreciate the  labours
 of his colleague to this end, that science was deprived of the benefit of Hunters
 anatomical description of five marsupial genera, because they were, in Dr. Shaw s
 estimation, little calculated for the readers of a zoological appendix.] 
472          HUNTER ON THE ANIMAL CECONOMY.
some species of one tribe  partaking of similar properties with a
species of another tribe.


                      Of the  Kangaroo.1*
  This animal (probably from its size)  was the principal one taken
notice of in this' island ;  the only parts  at first brought home were
some skins and skulls, and  I  was favoured with one of the  skulls
from Sir Joseph Banks.   As the teeth of such animals as are already
known in  some  degree  point out their digestive organs, I was in
hopes that I might have been able to form an opinion of the parti-
cular tribe of the animals already known  to which the kangaroo
should belong;  but  the teeth  did not accord with those  of any one
class of animals I was acquainted with, therefore I was obliged tc
wait with patience till I could  get the whole; and in many of its othei
organs the deviation from other animals is not less than  in its teeth,
In its mode of propagation it very probably comes nearer to the
opossum than any other  animal, although it is not at all similar to
it in other respects.  Its  hair is of a grayish-brown  colour, similar
to that of the wild rabbit of Great Britain, is thick  and long when
the animal is old ; but it  is  late in growing,  and when  only begun
to grow it is  like a  strong down; however, in some parts it begins
earlier than others,  as about  the mouth, &c.   In all the  young kan-
garoos yet brought  home (although some as large  as a full-grown
rat) they have all the marks of a fcetus : no hair; ears lapped close
over the  head;  no marks on the  feet of  having been  used in
progressive motion: the  large  nail  on the great toe sharp at the
point, and the sides of the mouth  united something  like the eyelids
of a puppy just whelped,  having only a  passage at the anterior part.
This union of the two lips on the sides is ofa particular structure ;  it
wears  off as it  grows up, and by the  time  it is the size of a small
rabbit, disappears.


                 Of the  Teeth of the  Kangaroo.
  The teeth of this  animal are  so singular that it is impossible from
them to say  what tribe it is  of.   There is a  faint mixture in them,
corresponding to those of different tribes of animals.   Take the mouth
at large, respecting the situation of the teeth, it would class in some
degree with  the  Scalpris  dentata,X in a  fainter degree with the
horse and ruminants; and  with regard to the line of direction of all
the teeth, they  are  very  like  those  of the Scalpris dentata.   The
fore teeth in the upper jaw agree with the  hog, and those in the
lower, in number, with the Scalpris dentata, but with  regard to

  * [The species  here  for the first time  described is  the  Macropus major  of
modern systems:  several other  species of the same genus have since been dis-
covered.]
  f [This tribe  includes the rat, &c. (it corresponds to the order Glires of Linnaeus
and the Rodentia of Cuvier.)] 
DESCRIPTIONS OF  SOME ANIMALS, ETC.         473
position,  and  probably  use,  with  the hog.   The  grinders  would
seem to be a mixture of hog  and ruminant, the enamel on their ex-
ternal and  grinding  surfaces rather  formed into several  cutting
edges than points.   There are  six incisors in the  upper jaw and
only  two  in  the lower, but  these  two are  so placed as to oppose
those of the upper ;  five grinders in each side of each jaw, the most
anterior of which is small.*
   The proportions  of  some  of the  parts of this  animal bear no
analogy to what is common in most others.  The disproportions in
the length between the fore legs  and the hind are very considerable,
also  in their strength, yet perhaps not  more  than  in the  jerboa.
This disproportion between  the fore legs and the  hind is princi-
pally in the more adult; for in the  very young, about the size of a
half-grown  rat, they are  pretty well  proportioned ;  which  shows
that  at the early period of life they do not use progressive motion.t
The proportions of the  different parts of which the  hind legs  are
composed  are very different.   The  thigh of the kangaroo is ex-
tremely short, and  the  leg is very long.   The  hind  foot is uncom-
monly long, on  which,  to appearance,  are placed  three  toes, the
middle toe by much the largest  and the strongest, and looks some-
thing like the long toe of an ostrich.   The outer toe is next in size;
and  what appears to be the inner  toe, is two  inclosed in one skin
or covering.  The great toe nail much resembles that of an ostrich,
as also the nail of the outer toe; and the  inner, which appears to
be but one toe,  has two small  nails, which  are bent  and  sharp.J

   * [Hunter appears to have taken this description from a skull in which the
 first deciduous molar was still  retained.  The total number of molares which
are developed in the jaws ofa  kangaroo are seven on each side of each jaw ; the
greatest number in use at any given  time is four on each side of each jaw ; a
posterior or fifth molar may  be visible above  the socket in the dry skull, but it
does not cut the gum for use till the anterior one is pushed out.
   The succession of the molares is from behind forwards  in  both jaws.  The
first deciduous molar, upper  jaw, resembles  the  first permanent false molar in
thepotoroo; it is elongated, compressed, and traversed  by a longitudinal sharp
middle ridge, at the internal base of which are three small tubercles.   It is for
cutting rather than bruising.  The  corresponding tooth, lower  jaw, is similar in
form, but smaller, and has one tubercle in the posterior part of the inner side of
the base.  In some species of  kangaroo,  as the Macropus elegans, the false molar
is permanent, but its earlier loss in Macr. major does not warrant a generic dis-
 tinction.   The second deciduous  molar  has  the form of the ordinary grinders,
but is smaller ;  it is shed before the first. The  third is similar, but somewhat
 larger; and so also of the fourth:  this grinder is much worn  in old skulls, and
 in the lower jaw is lost, leaving then  only |^-| molares inagedindividuals.  The
 fifth, sixth, and seventh follow each other  from behind forwards, and are  of
 equal size.
   Before the fourth grinder is in place the permanent innisores are gained ; these
closely resemble their predecessors, but are somewhat larger.   In the Macropus
major the exterior incisor upper jaw  presents two  inflected  folds of enamel ;
these are wanting in the corresponding teeth of the smaller species, which retain
 the spurious molares.]
   f [At a still earlier period the fore  legs, following the usual law of develop-
 ment, exceed the hind legs in length.] '
   X [Each of these toes has it proper  metatarsal and phalangeal bones.J 
474           HUNTER ON THE  ANIMAL  CECONOMY.
From the heel along the under side of  the  foot and toe, the skin is
adapted for walking upon.
   The fore legs, in the full-grown kangaroo, are  small in propor-
tion to the hind, or the size of the animal; the feet, or hands, are
also small.   The skin  on the palm is different from that on the back
of the hand and fingers.   There are  five toes  or fingers  on  this
foot, the middle rather the largest; the  others become very gradu-
ally shorter, and are all  nearly of  the  same shape.   The nails are
sharp, fit for holding.  The tail is long in  the old, but not so long,
inproportion to the size of the animal, in the  young.   It  would
seem to keep pace with the growth of the hind legs, which are the
instruments of progressive motion in this animal, and  which would
also show that the tail is a kind of second instrument in this action.*
The under lip is divided in the middle,  each side rounded off at the
division.  It has two clavicles, but they are short, so that the shoul-
ders are not thrown out.


                  The Potoroo  or Kangaroo Rat.X

   The head is  flat sideways, but  not  so  much so as in the true
Scalpris dentata.   The ears are neither  long  nor short, but much
like those of a mouse inproportion to the size of the animal.
   The fore legs are short in comparison  to the hind.   There are
four toes on the fore-feet,J the two middle are long, and nearly of
equal lengths, with long  narrow  tails, slightly bent;   the two side
toes are short, and nearly  equal in size, but  the outer  rather the

  * [It must be remembered that at this time  Hunter had never seen the living
kangaroo, but the numerous opportunities of  witnessing the locomotion of this
remarkable animal afforded  to subsequent observers have all  testified to the
sagacity of his provision of the use of the tail.]
  f [This animal differs from the kangaroo in having two small canines, in addi-
tion to the six incisors in  the upper jaw. The first compressed or false molar
on each side of each  jaw, which is shed  in the great kangaroo,  is here retained.
The first incisors of the upper jaw are also relatively longer and more curved.
The potoroo, therefore, forms the type ofa distinct  genus, which was named by
llliger ' Hypsiprymnus,'from the Greek word  ^T-^ivpv/uvos, signifying the hinder
parts raised.  Of this genus three or four species have been indicated.  The skin
and cranium of the individual described by Hunter, and figured in the Appendix to
White's Voyage, are preserved in the Museum of the College of Surgeons.  The
skull agrees in  size and form, as also  the proportions of the stuffed skin, with
the  skeleton of the  Hypsiprymnus murinus, given in Pander and D'Alton's
' Skelete der Beutelthiere,'' tab. iii.
   We give the  following admeasurements from the original specimen :

       From the end  of the nose to the vent   ...    1
       Length of the tail  ........    o
       Length of the skull    ......    0
       Length of the foot      ......    0
The Hypsiprymnus murinus of llliger is  the Hypsiprymnus White of Quoy and
 Gaiinard, the Macropus minor of Shaw.]
   X [In the specimen here described, as in  the  rest of the genus, there are five
 toes on the fore foot, but the fifth is so small  as scarcely to perform any part of
 the office of a toe..
in.	In.
3	0
8 3	3
3	3
 
DESCRIPTIONS OF  SOME ANIMALS, ETC.          475
largest.   From the nails on the two middle toes one would suppose
that the animal burrowed.  Their hind legs are long, and it is in
™eir power to stand either on the whole foot, or on the toes only.
On the hind legs are three  toes, the  middle one large, and the two
side ones short ;*  the tail is long.   The hair on the body is rather
thin ; it is of two  kinds, a fur, and a long hair, which last becomes
exterior from its length.  The fur is the finest, and is composed of
serpentine hairs; the long  hair  is  stronger, and is also serpentine,
tor more than two-thirds of its  length near to the skin, and termi-
nates in a pretty strong pointed end, like the quill ofa hedgehog ;
it is of a brownish-gray  colour, something like the brown or gray
rabbit, with a tinge of a greenish-yellow.
   It has a pouch on the lower part of the belly ;  the mouth opens
forwards, and the cavity extends backwards to the pubis, where it
terminates; on the abdominal surface of this pouch are four nipples
or two pair, each  pair placed very near the other.f

                       The Hepoona Roo.%

   This animal is of the size of  a  small rabbit; it has a broad flat
body;  the head a good deal resembles that of the squirrel; the eyes are
full, prominent, and large ; the ears broad and thin ; its legs short, and
its tail very long.   Between  the fore and hind legs, on each side,
is  placed a doubling of the skin of  the side, which, when the legs
are extended laterally, is as  it were pulled  out, forming a broad
lateral wing or fin, and when the legs are  made use of in walking, this
skin, by its elasticity, is drawn close to  the side of the animal, and
forms a kind of ridge, on which the hair  has a peculiar appearance.
In this respect it is very  similar to the flying squirrel of America.
   It has five toes,  on  each fore foot, with  sharp nails.  The hind-
foot has  also five toes, but differs considerably from the fore-foot;
one of the toes may be called  a  thumb,  having a broad nail, some-
thing like that of the monkey or opossum.   What answers to the
fore and middle toes  are united in  one common covering, and ap-
pear like one  toe with two  nails; this is somewhat similar to the
kangaroo.   The two other toes are  in the  common form ; these

  * [There are four toes on this foot, as in the  great kangaroo, but the two
inner ones are so conjoined by a common sheath of integument as to act as but
one.]
  f [The genera  Macropus and Hypsiprymnus are principally distinguished
from the other marsupialia anatomically by having a large stomach, complicated
with saccnli, produced as in the colon,  by being puckered upon longitudinal
bands.]
  X [This animal is the type of ihe genus  Pteaurus, which is characterized by
the following dental formula : incisors —, molares spuria; —, molares tubercu-
lar i-L?_ 34,  It  is the largest known species, and is the Pelaurus Taguanoides
of Desmarest, and  the Didelphys Pelaurus of Shaw.
  The  original  specimen, described and figured in White's Appendix, is pre-
served in the Museum of the Royal College of Surgeons.] 
476
HUNTER ON THE  ANIMAL CECONOMY.
four nails are sharp, like those on the fore foot.   This formation of
the foot is well calculated for holding anything while  it is moving
its body or its fore foot to other parts ; a property belonging (pro-
bably) to all animals which  move from the hind  parts, such  as  the
monkey, mocock, mongoose, opossum, parrot, leech, &c.   Its hair
is  very thick and  long, making a  very fine fur, especially on  the
back.  It is of a dark brown-gray on the upper part, a light white
gray on  the  lower  side of what  may be termed the wing, and
white on the  under surface, from the neck to the parts adjacent
to the  anus.

                      Wha  Tapoua Roo.*

   This animal is about the  size of  a racoon, is  of  a dark gray
colour on the  back, becoming  rather  lighter  on  the  sides, which
terminates  in a rich brown  on the belly.  The hair is  of two kinds,
a long hair and a kind of fur, and even the long  hair at the roots is
of the fur kind.  The head is short, the eyes rather prominent;
the ears  broad, not peaked.   The teeth resemble those of all  the
animals from that country I have hitherto seen.   The incisors  are
not continued  into the grinders by intermediate teeth, although there
are two teeth  in the intermediate space in the upper jaw, and  one
in the  lower.  The incisors are similar to those  of the kangaroo,
and six in number in the upper jaw, opposed  by two  in the lower,
which have an oblique surface extending some distance from their
edge, so as  to  increase  the surface of contact.  There are  two
cuspidati on  each side in  the upper jaw, and  only one  in  the
lower; five grinders on each side of each jaw, the first rather pointed,
the  others  appear  nearly of  the same  size,  and quadrangular in
their shape, with a hollow running across their base from the out-
side to the inner, which is of some depth; and another  which
crosses it,  but not so deep,  dividing ihe  grinding surface into four
points.   On the fore foot there are five toes, the  inner the shortest,
resembling, in a slight degree, a  thumb.  The hind foot resembles
a hand, or  that of the monkey and opossum, the  great toe  having
no nail, and opposing the whole  sole of the foot, which is bare.
The nails on the  other toes, both of the fore and  hind foot, resemble
in a small degree those of  the cat, being broad and  covered ;  and
the last bone of the toe has a projection on the under side, at the
articulation.   Each nail  has,  in  some degree, a  small  sheath,
covering its base when drawn up.t   The tail is  long, covered with

   * [This species is  now called the  vulpine opossum,  or vulpine phalanger
(Phalangista  Vulpina,) and is the type of a genns of  which the species are not
confined to Australia, but  some were known, as inhabitants of the Indian isles,
to the older naturalists.  The dental characters are described in the text.]
   f [In the hinder foot the two toes next the thumb  are inclosed in a common
sheath  of integument as far as the ungual phalanx : this is the commencement of
that peculiar degradation of the second and middle toe which is carried  to so
great an extreme in the kangaroos and potoroos.  The  term Phalangista was
given to the  genus in  question  in consequence of this binding together of the
phalanges of two of the toes in the hind feet.] 
            DESCRIPTIONS OF SOME ANIMALS, ETC.         477

long hair, except the under surface of that half towards the termi-
nation of the breadth of half an  inch, becoming  broader near the
tip or termination:  this surface is covered with  a strong cuticle,
and is adapted  for laying hold.
                   The Tapoa Tafa,or Tapha.*

   This animal is the size of a rat, and has very much the appear-
ance of the martin cat, but hardly so long in the body in proportion
to its size.  The head is flat forwards, and broad from side to side,
especially between the eyes and ears; the nose is peaked, and pro-
jecting beyond the teeth, w hich makes the upper jaw appear to be
considerably longer than the lower; the eyes are pretty large; the
ears are broad especially at their base, not becoming regularly nar-
rower to a point,f nor with a very smooth edge, and having a small
process on the concave or inner surface, near to the base.  It  has
long whiskers from the sides of the cheeks, which begin forwards,
near the nose, by small and short  hairs, and become  longer and
stronger as they approach the eyes.J  It  has very  much the hair
of a rat, to which  it is similar in colour; but near to the setting on
of the tail it is of a  lighter brown,  forming a broad  ring  round it.
The fore feet are shorter than the hind, but much in the same pro-
portion as those of the rat; the hind feet are more flexible.  There
are five toes on the fore feet, the middle the  largest, falling off on
each side nearly equally;  but the fore or inner toe is rather shortest;
they are thin from  side to side;  the nails are pretty broad, laterally,
and thin at their base; not  very long, but sharp: the animal walks
on its whole palm,  on winch there is no hair.   The hind feet  are
pretty long, and have five toes; that which  answers to our  great
toe is very short, and has no nail;  the  next  is  the  longest in  the
whole, falling  gradually off to the outer toe ; the shape of the hind
toes is the same as  in the fore feet, as are  likewise the nails;  it
walks nearly on the whole foot.  The tail is long, and covered with
long hair, but not all of the same colour.  The teeth of this creature
are different from  any other animal yet known.   The  mouth is full
of teeth; the lower jaw narrow, in comparison to the  upper, more
especially backwards, which allows of  much broader  grinders in
this jaw than in the lower, and which occasions the grinders in the
upper jaw to project considerably over those in the lower.  In the
middle the cuspidati oppose one another;  the  upper  piercers  or
holders go behind  those of the lower; the second class  of  incisors
in the lower jawr overtop those of the upper,  while the  two first in
the lower go within, or behind those of the  upper.  In the upper

  * [This animal is the Phascogale penicillata of Temminck,  (Monographies de
Mammalogie, p. 58.), Dasyurus Tafa of Geoffroy, Didelphis penicillata of Shaw.]
  f [Temminck describes the ears of Phascogale penicillata as being "arrondies
par le haut."—Loc. cit., p. 59.]                  ^                 „
  ± ["■ Les moustaches des levres sont places plus pres des yeux que de nez.  —
Ibid.} 
478           HUNTER ON THE ANIMAL CECONOMY.
jaw, before the holders ' (canines)', there are four teeth ' (incisors)'
on each side, three  of which are pointed, the  point  standing on
the inner surface; and the two in  front are longer, standing  more
obliquely forwards, and appear to  be appropriated for a particular
use.*
   The holders * (canines)' are a little way behind the last fore teeth,
to allow those of the lower jaw to come between ;  they are pretty
long.
   The cuspidati (spurious molares) on each side become longer and
larger towards the grinders (true molares); they are points or cones
placed on a broad base.
   There  are four grinders on each side, the middle  two the largest,
the last the least; their base is a  triangle, of the scalenus kind, or
having one  angle obtuse  and  two  acute.  Their base  is composed
of two surfaces, an  inner  and an outer, divided by  processes  or
points; it is the inner that  the  grinders of  the lower jaw oppose,
when  the mouth is regularly shut.
   The lower jaw has three fore teeth, or incisors, on each side, the
first considerably the largest, projecting  obliquely forwards: the
other two of the same kind,  but smaller; the last the smallest.
   The holder (canine) in  this jaw is not so large as in the upper jaw,
and  close to the incisors.
   There  are three cuspidati ' (false molares),f the  middle  one the
largest, the last  the  least: these are cones  standing on their base,
but not on the middle, rather on the anterior side.
   There  are four grinders,  the two middle the  largest, and rather
quadrangular, each   of which has a  high point or cone on the
outer edge, with a smaller, and three more diminutive on the inner
edge.
   It is impossible to say critically  what the various forms of these
teeth are adapted for, from the general principles of teeth.   In the

  * [This superiority of size of the two  middle incisors of the two jaws is one
of the characters which distinguish Phascogale from Dasyurus."]
  t [This is  the second and most decisive distinguishing generic character
between Phascogale and Dasyurus, the latter having only two  false molars on
each side of each jaw, instead of three.  Had Fischer, Lesson, and other zoologists
compared the description of the teeth in  the text with that gi/en by Temminck
in his Monographies de Mammalogie,as characterizirg his genus Phascogale, they
could not have hesitated to refer the Tapoa tafa of Hunter to that genus, and the
catalogues of mammalia  need not have contained the imaginary species Dasyurus
Tafa, which M.  Temminck  observes  " n'a point ete  vue  depuis par  aucun
naturaliste," and which  species Lesson suspects to be founded on the immature
state of the spotted Dasyure (Dasyurus viverrinus).  But neither observation nor
analogy favour the idea of spots  being  acquired  by age; on the contrary, the
examples of the lion and the  puma, which are spotted only  when young, show
that they are more likely to be lost.
  In the Hunterian collection the posterior half of  the body of the individual
described by Hunter is  preserved, to show the  marsupium and teats;  these are
eight in number, and arranged in a circle.  The tail  perfectly corresponds with
the specimens of Phascogale penicillata,  and with  M. Temminck's  description,
being "couverte de poils assez courts a  la base, tres-long, raides, et en pinceau
vers la pointe" (loc. cit., p. 59); and the long hairs are black.] 
DESCRIPTIONS OF SOME ANIMALS, ETC.         479
front  we have what may divide  and tear off;  behind  those there
are holders or destroyers;  behind the latter, such  as will assist in
mashing, as the grinders of the lion, and other carnivorous animals;
and last of  all, grinders, to divide parts into smaller portions, as in
the graminivorous tribe ; the articulation of the jaw, in some degree,
admits of all those motions.

            A Dingo, or Dog  of New South  Wales.

   This animal is  a variety of the dog, and, like the shepherd's dog
in most countries, approaches near  to the  original of  the species,
which is the wolf; but is not so large,  and does not stand so high
on its legs.  The ears  are short  and erect, the tail rather bushy;
the hair, which is of a reddish-dun  colour, is  long and  thick, but
straight.   It is capable  of barking,  although not so readily as the
European  dog, is very ill-natured  and vicious, and snarls, howls
and moans like dogs in common.   Whether this is the only dog in
New  South Wales, and whether they have it in a  wild state, is not
mentioned, but I  should be inclined to believe they had no other, in
which case it  will constitute the wolf of that country; and that
which is domesticated is only the wild  dog tamed, without having
yet produced  a variety, as in some parts of America.
THE END. 
 
           ADVERTISEMENT

To the First Edition of the Animal (Econejmy, 1786.
  The nine following papers have been read at the Royal
Society, and published in the Philosophical Transactions;
but in a work of so general a nature, and of which physio-
logical inquiries make so small a part, the few facts and
observations which I have given upon such subjects may
probably be overlooked by those who are not members of
that Society.  That they may be more easily procured by
students in medicine, and other readers, I have, by an ap-
plication to the President and Council of the Royal So-
ciety, obtained leave to reprint such of them as I  consider
to be connected with the principles and  actions of the Ani-
mal (Economy; and I have added such observations and
remarks as have occurred to me since the time they were
read before the Royal Society.
2 
            ADVERTISEMENT

To the Second Edition of the Animal (Economy, 1792.
  Eleven of the following papers have been  read  at the
Royal Society, and published in the Philosophical Trans-
actions ; but in a work of so general a nature, and of which
physiological inquiries make so small a part, the few facts
and observations which I have given upon such subjects
may, probably, be overlooked by those who are not mem-
bers of that Society.  That they may be more easily pro-
cured by students in medicine, and other readers, I have,
by  an application to the President and Council of the
Royal Society, obtained leave to reprint them, in this work,
as being connected with the principles and actions of the
Animal  (Economy; and I have added such observations
and remarks as  have occurred to me since the time they
were read before  the Royal Society. 
PREFACE.
  Always an admirer  of  the genius of Hunter, and of late  years
obliged by official duties to make frequent reference to his numerous
and  varied  productions, especially to those which are scattered
through different volumes of the Philosophical Transactions and
other works, I have often  felt the inconvenience that resulted from
the absence  of a uniform edition of the whole of the extant works
of that great and original thinker.   When, therefore, Mr. Palmer
first communicated to me  his design of publishing a new edition of
Hunter's works, I heard with peculiar satisfaction his intention  to
include in the proposed collection every memoir of the author that
could be found  in  print, and I gladly lent  my assistance, which,
however, the previous assiduous  researches of Mr. Palmer rendered
of little  moment, towards completing a  list of all the published
essays or observations on  various parts of the ' Animal (Economy'
which had not before been included in  the work so entitled.   The
proposal which Mr. Palmer at the same time made to me to edit
this portion  of the works of Hunter I declined, from a sense of the
inadequacy of my powers  to grapple  with so vast a range of im-
portant  physiological subjects as the contemplated  volume must
necessarily embrace, and I sincerely hoped that Mr. Palmer would
have found a coadjutor better qualified than myself to  do justice to
this portion of his most useful and praiseworthy undertaking.
   After  a  lapse of nearly two years Mr. Palmer again applied
to me to revise the papers on the  Animal  (Economy, and I then
acceded reluctantly to  his request, led, by the sole motive of accele-
rating the appearance of a much wished-for edition, to  a task, to
which I have since dedicated a great portion of my leisure hours,
without the  slightest expectation of profit or honour, the experiment
having only served to convince me of the difficulty of adding the
observations demanded by the progress of science to  the text of
Hunter in the  spirit of its  author, and a retrospect of my annota-
tions leading me to suspect that often, with every wrish to  avoid it,
I may have tacitly implied an ignorance on the part  of  Hunter of
facts'with which he was probably well acquainted, and to perceive
that, in general, the addition of such  details tends to  overload and
destroy the  force of the original observations in the text.
   It is with much  more satisfaction that  I  refer to  the  additions
Which have been made to the present edition of  the Animal (Eco-
nomy of the  hitherto uncollected or unpublished writings of its
original author. 
8
HUNTER ON THE ANIMAL OECONOMY.
  These consist of the following essays.
             From the Philosophical Transactions:
  " On the Anatomy of the Siren or Amphibious Bipes (1766)."
  "On the Electric Organs of the Torpedo (1772)."
  "On the Electric Organs qf the Gymnotus (1755)."
  " Experiments and Observations on Vegetables with  respect to
the power of producing Heat (1775)."
  "A  case  of Small-pox communicated  by the  Mother to the
Foetus (1780)."
  " Anatomical Remarks on  a New Marine Animal (1785)."
  "Observations on  the Structure  and   (Economy  of  Whales
(1787)."
   " On Bees (1792)."
  " On the Fibrous Structure of the Crystalline Lens (1793)."
  " On the Fossil Bones of the Caverns of Gailenreuth (1794)."
  " Six Croonian Lectures read before the Royal Society by Hunter
in the years 1776,  1777, 1779, 1780, 1781, and 1782," but with-
drawn from publication by the Author."
    From the Medical Commentaries of Dr.  William Hunter:
  " Experiments on Absorption by Veins."
  From the Transactions of a Society for the  Promotion of Medical
and Chirurgical Knowledge,  vol.  ii. (1794):
  " Description of the Human Uterus and Ovum in  the first Month
of Pregnancy."
  " Observations on the Growth of Bone."
   There is also added,
  " An Account of the  Anatomy of the  Jerboa,"  contributed by
Hunter to the  Appendix to Russel's History of Aleppo.  And,
lastly,
   " Descriptions of Five Marsupial  Quadrupeds," from  the Zoo-
logical Appendix to White's  Voyage to New South Wales.  (1790.)
   In order to bring these different memoirs  in juxtaposition with
papers on analogous subjects in the original  edition of the Animal
(Economy, a slight alteration has been made in the arrangement
of the different essays  composing that work.   Those which  relate
to generation are brought together at the beginning of the volume;
then follow the observations on digestion, animal  heat, and other
physiological  subjects;  and lastly,  the  papers  of a  descriptive
character, which refer more immediately to  comparative  anatomy
and zoology.  Thus for the first time are collected into one volume
the physiological and anatomical stores, from which, in connexion
with  the materials composing his museum or destined for its illus-
tration, an adequate idea may be formed of the nature of the great
work in which Hunter had purposed to record the sum  of his vast
experience.
   In the year 1786,  when  Hunter published a collection of  his
detached memoirs in the first edition of the Animal (Economy, he 
PREFACE.
9
observes, with reference to the  subject of digestion, " I  cannot at
present spare sufficient time to give my opinions  at  large  on this
subject, with all the  experiments and observations  I  have made
upon it, but as soon as I have leisure  I shall  lay  them before the
public."  And again,  in describing the organ of hearing  in fishes,
he premises that he reserves a more complete investigation of this
part of natural  history " for a  larger work on  the structure of
animals, which I one day hope to have it in my power to publish,"
and he  states that ever  since the year 1760  his  researches  have
been continued  in every part  of the animal ceconomy.  Hence
instead of regarding the uncommon structures which  he discovered
in his dissections of different animals as individual peculiarities, he
was enabled to advance beyond  the anatomists of his  own times,
and  view  them from the same eminence  to  which subsequent
induction has raised the observers of the present day;  and referring
to the series of preparations in his museum, he  boldly  states with
reference to the  structure of the  organ of hearing  in fish, that it is
"only a link in the chain of varieties displayed in the formation of
this organ of sense in different  animals, descending from the most
perfect to the most imperfect in a regular progression."
   The importance of  these views, and the nature and amount of
the knowledge which  they indicated,  could not be appreciated by
the contemporaries of Hunter in the absence of a detailed  exposi-
tion of the evidences on which they were founded.   It is no wonder,
therefore, that we find his earlier eulogists sometimes founding his
claims  to  scientific  eminence   on  insecure  grounds;  some,  for
example, lauding him as the author of a theory of the organizing
energy,  which may be traced  to the  time of Aristotle, or  as the
originator of the doctrine  of the  vitality of the  blood,  which is
supported with  so much eloquence by Harvey and his immediate
successors;  while others, taking more definite grounds, have often
unfortunately selected as his discoveries precisely those subjects of
Hunter's special researches in which he had  but  revived  and ex-
tended the ideas of his predecessors.   Of this we have a striking
example in the introductory observations on the character of Hun-
ter contained  in Sir  Everard Home's Lectures  on  Comparative
Anatomy, vol.  i., p.  6, in which the  independent function of the
vesicula? seminales and the determination of the organ of hearing
in fishes are adduced as Hunterian discoveries.
   The  true originators of these  and of other ideas and facts which
Hunter may have regarded as his discoveries, and which he doubtless
did discover so far as independent and original research constitutes
a claim to that honour, I have been careful to point  out  in every
case where my reading has led  me to detect in an older author a
clear anticipation of  Hunter.
   It cannot be doubted, however, that the ascription  to Hunter  by
his friends and admirers, of facts and  opinions to which he had no
title as the  original discoverer, must have contributed to  lower his
character  in  the  estimation of continental anatomists;  whose
                               2* 
10
HUNTER ON THE ANIMAL GfJCONOMY.
acquaintance with the vast accumulation of facts in comparative
anatomy due to the labours of the numerous cultivators of that sci-
ence in the sixteenth and seventeenth centuries, easily enabled them
to detect the weakness of such claims, without perhaps their possess-
ing such a knowledge of  Hunter's labours  as  to justly appreciate
their scope and tendency,  and to view them, as they deserve to be
viewed, in the light ofa first great attempt to arrange in  one  con-
catenated system the diversified facts in comparative anatomy.
  Cuvier, for example, in  his review of the  progress of science in
the latter half of the eighteenth century, a period which may be re-
garded as a second revival of comparative anatomy and physiology,
places Hunter in an inferior category of contributors to those sciences.
After eulogizing the share  which the erudite Haller took in demon-
strating the importance of comparative anatomy to the  advance-
ment of physiology, and the corresponding effects which the labours
of Daubenton and Pallas produced in establishing sounder ideas of
the classification of animals, the  historian of the  natural sciences
goes on to state : " John  Hunter in England, the two Monros in
Scotland, Camper in  Holland, and  Vicq D'Azyr  in  France,  were
the first who followed their footsteps.   Camper," he observes," cast,
so to say, a passing glance of the eye of genius on a number of in-
teresting  objects, yet almost all his labours  were  but  sketches.
Vicq D'Azyr, with more  assiduity, was arrested by a premature
death in the midst of a brilliant  career ;  but  their  works inspired a
general interest, which has ever since been  on  the increase."
   With reference to the nature or influence of the labours of Hunter,
Cuvier is silent;  he limits himself  to an  indication in a marginal
note of the Treatise on the Teeth and " les  autres ecrits de  Hunter
inseres en partie dans les Transactions Philosophiques."*
   This  was meting out  but scanty justice to the  author of the
Treatise on  the  Blood and of  the  Observations on  the  Animal
GEconomy, which abound with  so  many  general  propositions in
comparative anatomy and  physiology.  If, however,  this opinion
of  Cuvier be excusable  under the circumstances under which it
was written, it would  be unpardonable not to appeal against it upon
the evidence of the higher claims of Hunter afforded by the present
edition  of his works and by those manuscripts which have already
appeared in the catalogue of his Physiological collection published
by the Royal College of Surgeons.   Had these manuscripts, expla-
natory of the design  of the Hunterian collection, been  published
before Cuvier wrote  the  work  from  which we have just quoted,
that  astonishing  result  of Hunter's labours might  perhaps  have
claimed a passing  notice  from one  whose statements all Europe
now receives and all posterity  will  regard  with confidence and
 respect.
   " Les autres ecrits," the " other  writings" of Hunter  to which
 Cuvier alludes, are indeed  devoted rather  to  the development of

   * Histoire des Progres des Sciences Naturelles, depuis 1789, torn, i., p. 302 
PREFACE.
11
general principles in physiology than to the detail of the anatomical
observations  upon which he  founded them.   Many of the facts
ascertained in the course of his  higher  and more comprehensive
inquiries, and incidentally alluded  to in the narration, are however
fully as interesting and important as those which other anatomists
have  sometimes thought worthy of being made  the  subjects of
express monographs.
  But Hunter had higher aims  than the reputation ofa mere  col-
lector of facts in comparative anatomy; and this he not only  felt
but had expressed in an early  period of his career.  In  a manu-
script, copied by Mr. Clift, relating  to a  dissection of a  turtle, he
says,  " The late Sir John Pringle, knowing of this dissection, often
desired me to collect all  my dissections of this animal, and send
them  to the Royal Society ;  but the publishing ofa description  ofa
single animal, more especially a common one, has never been my
wish."
  Howsoever we ma}' regret  this feeling, which has undoubtedly
deprived the world of the results of much inestimable  labour,  and
has operated  in various ways  disadvantageously to  Hunter's own
reputation, yet it indicates the expanded views of the man who en-
tertained it.
  Had Hunter published seriatim his notes of the structures of the
animals which he dissected,  these  contributions  to comparative
anatomy would not only have vied with the labours of Daubenton as
recorded in the Histoire Naturelle of Buffon, or with the Compara-
tive Dissections of Vicq d'Azyr which are inserted in the early
volumes of the Encyclopidie Melhodique  and in the Mimoires  de
l'Academie Royale de France, but they would have exceeded them
both together.
   It would be tedious  to enumerate, name by  name, the  different
species of animals whoseorganization was investigated and recorded
by Hunter.   Mr. Clift  has  evidence* that  he  left  written descrip-
tions, from autopsy, of the anatomy of the following Mammalia:
Of Quadrumana	21 Species.
Carnivora .	51
Rodentia	20
Edentata	5
Ruminantia .	15
Pachyderma	a . . 10
Cetacea	6
Marsupiata .	10
Of Birds .	84 Species
Reptiles	25
Fishes	19
Of Insects.	29 Species
and radiala, upwards of twenty.  From the titles of manuscripts,
 ♦ See " Evidence before the Medical Committee of the House of Commons." 
12
HUNTER ON THE ANIMAL CECONOMY.
 therefore, it appears that Hunter possessed, at the period of his
 decease,  original records of  the dissections of three hundred and
 fifteen different species of animals.
   In addition  to these,  Hunter's preparations testify that he had
 dissected twenty-three species of mammalia, sixteen species of birds,
 fourteen species of reptiles, forty species of fishes, forty-two different
 mollusca, and about sixty species of articulate and radiate animals;
 all species of animals of whose anatomy we have no evidence that
 he left written descriptions.   So that  by adding these undescribed
 dissections to those of  which we derive the  evidence from the list
 of the manuscripts, and of which described dissections his anatomi-
 cal collection in like manner  contains  evidences in the dissected
 and preserved  organs,  there is proof that Hunter  anatomized at
 least five hundred different species of animals, exclusive of repeated
 dissections of different  individuals of the same  species, besides the
 dissections of plants to  a  considerable amount.
   With respect to the rarer and  less known invertebrate animals,
 Hunter was not content with  merely recording their structure and
 displaying its leading peculiarities in preparations ; but he caused
 most elaborate and accurate drawings to be made from the recent
 dissections ; for which purpose he  retained in his family many years
 an accomplished draughtsman, Mr. William Bell, better known as
 the author of two papers in the  Philosophical Transactions, de-
 scriptive of the  Sumatran Rhinoceros and the Ecan  Bonna (Platax
 arthriticus, Cuv.).  Several examples of these beautiful designs have
 already been published  by the Council of the Royal College of Sur-
 geons in the illustrated  catalogue of the Hunterian Museum: they
 relate to  the anatomy of the Sepia and Solen, of the Ascidia and
 Salpa;  they illustrate the circulation of the blood in the Crustacea
 and Anellida ;  and the figure which Mr. Hunter has given of the
 circulation in  the Chloeia capillata, a red-blooded worm, far sur-
 passes in  beauty and  detail any of  those with which Cuvier illus-
 trates the memoir* dedicated to  what  he regarded to  his latest
 breath as one of his most  interesting discoveries.
   Hunter had also minutely investigated  the anatomy of the cir-
 ri peds ;f but of his dissections of these, as of many  other animals,
 it is to be lamented that the preparations and drawings are now the
 sole evidences.   The illustrations of the anatomy of the Echinoder-
 mata, both of the spiny species and of the unarmed Holothuria,
 have  never been  surpassed  either  as to  minuteness or accuracy;
 and, excepting  the disputed article of the  nervous system, little is
 added in the elaborate and well-known monograph of Tiedemann,
 to the anatomy of the Holothuria as it is displayed by Hunter.J
   Now the anatomical labours of Daubenton were confined to that
 class  of animals whose  structure most nearly resembles man;  he

  * Bulletin de la Soc. Philomath., 1791, p. 146.
  f See Physiological Catalogue of the  Hunterian Collection, vol. i.f p. 255
pi. IV.
  ± Ibid., p. 251, pi. HI. 
PREFACE.
13
describes the position and length and breadth and number of parts
with most praiseworthy zoological precision, but never appears to
raise his thoughts to the relations of the structures he detected with
the habits of the species, or their  adaptation to function.   Hence
he has been said to have  made  more discoveries of which he was
unconscious than any other cultivator of comparative anatomy.
  Vicq d'Azyr, on the contrary, adorns his descriptions with many
beautiful and philosophical views, but he  did not carry his  scalpel
beyond the vertebrate series ; while Hunter explored every  modi-
fication of animal structure, from man down to the polype.
   If Hunter surpassed his contemporaries in the value and amount
of the materials which  he collected in comparative anatomy, he
rises far above them in the application  of his facts.
   By a profound and unremitting meditation on the diversities of
structure presented to his view, he derived more accurate notions
than were current amongst his  contemporaries of the parts essen-
tial to the performance of the different  functions, and every idea or
doubt thus suggested he tested by the most varied, ingenious, and
accurate experiments.
   "Many things," he observes, " arise out of investigation  which
were not at first conceived ;  and even misfortunes in experiments
 have brought things to our knowledge that were not, and probably
 could not have been, previously conceived.   On  the other hand, I
 have often devised experiments by the fireside or in my carriage,
 and have also  conceived the result; but when I tried  the  experi-
 ment the result was different, or I found  the experiment could not
 be attended with all the  circumstances that were suggested."*
 Few physiologists indeed,  if any, have made more numerous, va-
 rious  and conclusive experiments than Hunter.  Yet he says,  " I
 think it ma^ iJe set down as an axiom that experiments should not
 be often repeated which merely tend to establish a principle already
 known and admitted, but that the next step should  be the applica-
 tion of that principle to useful purposes."!
   By this series of labours of mind  and hand, prosecuted uninter-
 ruptedly from year to year, Hunter  at length came to establish a
. body of physiological doctrines,  to the happy influence  of which
 on the  treatment of the various " ills that flesh is heir to," every
 cultivator of the healing science now bears grateful testimony.
   Most of the enlightened physiologists  of this  country have  ac-
 knowledged the  high merit  and beneficial influence  of Hunter's
 labours ;°but  the general terms in which his merits have been ex-
 pressed have not availed in raising him  from the secondary cate-
 gory of contributors to comparative anatomy, in which he has been
 classed by Cuvier, and from which  some continental writers have
 lately been disposed to degrade him.J

   * Animal Economy, p. 417 (the pages throughout refer to the present edition).
   f Ibid., p. 117.
   ± See the Esquisse Hislorique sur PAnalomie Comparee, prefixed to the French
 translation of the second edition of Carus's Comparative Anatomy, vol. i., p. xxx. 
14
HUNTER ON THE ANIMAL CECONOMY.
   The present seems, therefore,  to  be a fitting  opportunity to
 attempt  to define the grounds for assigning a higher station to
 Hunter,  considered  as  a physiologist and comparative anatomist.
 In this endeavour, however, to prove what Hunter was as a dis-
 coverer,  we must also fairly state what  he was not.
   He has been spoken of as the originator of the idea of a subtle.
 imponderable principle  operating  in  the fluids and  solids of the
 organism, and causing the  phasnomena  of life.  But  such a  prin-
 ciple, under various  names and with various  attributes, has been
 assigned as the cause of organization by Aristotle,  Harvey, Willis,
 Cudworth, Grew, Van Helmont, and Siahl.
*   As both Harvey and Hunter had spent laborious lives  in earnest
 inquiries  and repeated dissections  and experiments, to  ascertain
 relations between structure and function; as both  had studied the
 changes  which take  place  in the form  and  structure of animals
 from their embryo state to  that of maturity ; and as both had care-
 fully traced the  successive phaenomena which occur in the  egg
 during incubation,—the  similarity  of their opinions on the nature
 and powers of the vital principle is correspondingly close.
   Both arrived at the conclusion, that an animating principle exists
 and  operates  in the  ovum prior to  the formation of any organ of
 the future animal.  Both  attributed the power by which the fecund
 egg resists putrefaction, while  the unprolific one decomposes, to  a
 principle of life, which Harvey more precisely terms the " anima
 vegetiva."*
   Hunter, however, carries his researches a step further; he sub-
 mits the fecund  egg to a low temperature, and ascertains  a new
 property, of which  Harvey was ignorant, a  power, viz., of resist-
 ing cold : he also shows that when once frozen, and killed by cold,
 the dead impregnated egg yields to putrefaction like the  unimpreg-
 nated one.
   Both physiologists observed that if  the phsenomena  of a vital
 principle were manifested in one part of  the organization  more than
 in another, it  was in the  blood.  " For the blood," says Harvey,
 "is the first formed,  and  is the primary  animate particle of the em-
 bryo;  it  is generated prior to the punctum saliens,  before the  first
 rudiment of the heart, and is endowed with the vital heat or princi-
 ple before it begins to move, and from it does pulsation commence.


   * "Plurimum  itaque mecum ipse repntavi, qui fieret, ut ova improlificagal-
 linaB supposita, ab eodem calore extraneo corrumpar.tur, putrescant, et fcetida
 evadant; ovis autem fcecundis idem non  contingat."  Harveii De  Generatione
 Animalium Exercitatio 22.
   "Ovum itaque est corpus naturale virtute animali praeditum ; principio nempe
 motus, transmutationis, quietis, et conservationis." Exercit. 26.
   " Cum enim in ovo macula prius dilatetur,  colliquamentum concoquatur  et
 praeparetur, plurimaque alia (non sine providentia) ad pulli formationem  et in-
 crementum instituantur,  antequam quidpiam pulli vel ipsa primoo-enita ejus
 particula appareat; quidni utique credamus  calorem innatum animamque pulli
 vegetativam ante pullum  ipsum exsistere ?"  Exercit. 57. 
PREFACE.
lfi
For the thing containing is made to be serviceable to the thing con-
tained.
  " Nor is the blood therefore to be call the primogenial part, be-
cause that in and from it the organ of pulsation is derived, but also
because  the  animal heat and vital principle are first implanted
therein;  and in it does life consist. For where  heat  and motion
first begin, there  also life doth first arise and last expire. "—Harvey,
On Generation, pp. 274, 275.
  This explicit and beautiful enunciation of the preexistence of the
blood to  the  machine by which it is mainly circulated, and of its
endowment of life, fell  barren from the pen of Harvey (if we except
the brief practice of transfusion  to which it gave rise), and was for-
gotten, when  Hunter resumed the inquiry.  And why, it may be
asked, was the doctrine of the vitality of the  blood inoperative, as
taught by Harvey?   Because instead of establishing that doctrine
by observations and experiments, from  which  alone it was suscep-
tible of deriving further proof,—instead of applying the principle to
the explanation of the  phenomena of disease, and to a modification
and improvement of remedial measures, Harvey obscures and for-
gets the conclusion of his cooler moments of observation, and, as
the learned Barclay well observes, excited  by the discovery which
had extended his fame so widely over Europe, and had  reflected
such  lustre on his name and  country,  he expatiates on the  blood
as something divine ; he has recourse  to hyperbole, and describes
its properties in the extravagant language of romance.
  Hunter, on the contrary, carries a series of calm and philosophi-
cal investigations on the vital properties of the blood  to an extent
which has never  been  surpassed ;  he examines it under every con-
dition, both in the vessels and out of the vessels, during circulation
and at  rest,  in health and in disease.  He aims to establish the
period in  its  formation  at which it manifests  the vital  properties;
and he fully details the changes which it undergoes, and the pheno-
mena which  supervene in the  rest of the organism when these pro-
perties are lost.  Lastly, he tells us how the blood, by  means of its
vital  properties, assists in the  restoration of parts when injured or
fl I ^P*"l ^Pfl
   Hunter subjects the blood to both mechanical and chemical analy-
sis, and endeavours to determine the characteristic properties of its dif-
ferent constituents.  It was not known in his time upon which  of
these constituents the  act of coagulation depended.   Hunter took
advantage of a case in which  the red globules subsided, as in some
cases thev do, more rapidly than usual, and skimming off the super-
incumbent colourless fluid, found that the fibrin, as it is now termed,
immediately coagulated and formed a  colourless clot.*  A  subse-
quent erroneous  theory, which  attributed the  act of coagula ion to
the red globules, has recently been set aside by the application of
an ingenious process for artificially separating the fibrin from the
* Treatise on the Blood, &c, p. 32. 
1G           HUNTER ON THE ANIMAL CECONOMY.

blood disks  before coagulation takes place, and the opinions of
Hunter on this point have  been fully established by the experiments
of Miiller.   With respect  to the serum, Hunter instituted a number
of experiments and made  many ingenious observations to determine
the relative quantity  of the coagulable to the uncoagulable  part.
His deductions as to the amount of nutrient albumen in the blood
of animals of different  ages, and under different circumstances, as re-
gards exercise or rest, &c, formed, from observing the quantity of
gravy or uncoagulable serosity which different roasted meats afforded,
is highly characteristic of hisoriginal and ever active mind.  In seek-
ing to determine the respective importance of the different constitu-
ents of the blood, by the philosophical and most difficult inquiry into
their  respective  periods  of formation in  the  development of the
embryo, Hunter  made the interesting discovery that the vessels of
the embryo  ofa  red-blooded animal  circulated in the first instance
colourless blood, as in the  invertebrate animals.
  " The red globules," he observes, " seem to be formed later in
life than the other two constituents, for  we see while the  chick is
in  the egg the heart beating, and  it then contains a transparent fluid
before any red globules are formed, which fluid we may suppose to
be the serum and the lymph."*
  I well remember the  feelings  of surprise with which I  listened
while at  Paris in 1832 to a memoir read before the Academy of
Sciences by MM. Delpech and Coste, the object of  which was'the
announcement of the same fact as a novel and important discovery.
The statement of the French  observers was received with all the
consideration which its importance justly merited, without its being
suspected  that our great physiologist had half a century before  em-
braced it,  with all  its  legitimate  deduction, in  the extended circle
of his investigations.
  In the same spirit in which he investigated the nature of the blood
he also pursued his  researches on  the properties of the solids; he
endeavours to determine the specific  powers and vital phenomena
of the nervous system and of the stomach ; he compares these im-
portant parts of the  animal body, with  reference to the degree of
energy with which their functions are manifested ; he considers the
influence which they reciprocally exert  in maintaining the vitality
of the blood, and the relative dependence of the whole organism on
the integrity of their vital  powers.   He also dwells at great length
on the sympathies resulting from  these mutual relations and de-
pendencies.
  In all his physiological  researches we may see that instead of
dogmatising on  the powers and virtues of an abstract essence,
Hunter endeavours to analyse the vital forces peculiar to each
organic element, and to classify, as it were, the phenomena of which
life consists.
  If we turn from Hunter's researches on life to his investigations
* Treatise on the Blood, &c., p. 71. 
PREFACE.
17
on another equally difficult and recondite subject in general physio-
logy, viz., Animal, or rather, Organic Heat, we see the same exer-
cise  of the powers of the same great and original  mind.
  He first determines  the relative extent to which the power of
generating heat or  resisting cold is enjoyed in the two grand divi-
sions of organic nature, plants and animals: he next investigates the
degree  in  which that  power is  possessed by different classes of
animals; then the relation subsisting  between that degree and the
perfection and complexity of the organization with which the power
is associated. He anticipates some modern physiologists in determin-
ing the  different power of generating heat  manifested by the same
species  at different periods  of life, and advances  a step further by
considering the different powers of resisting cold which different
parts of the same organized body possess in  relation to their re-
spective ages and periods of formation.*   He lastly analyses, so to
say, the different functions,  to determine in what degree the pro-
duction of heat depends on their exercise; and reciprocally, the in-
fluence  of the temperature of the body upon the active and healthy
maintenance of their function.
   Throughout all this  beautiful and justly celebrated inquiry we see
the philosopher  conscious of the extent of his  powers, and  of the
kind of knowledge which the right  exercise of those powers  was
adapted to acquire.  We now here perceive a trace  of a desire to
establish a theory of the nature of animal heat in the  abstract.
   Let any one compare the language of Harvey or of Willis, while
expatiating on the calidum innatum, with the following just remark:
"I shall not," says  Hunter, "attempt to  settle whether heat  is a
body or matter, or only a property of matter, which appears to me
to be merely a  difference in terms, for  a property must belong to
something."t
   It is precisely in the same spirit that he conducts his researches
on life ; and I would say, after a very careful study of the writings
of Hunter, that of all physiologists he is one to whom a dogmatic
theory of abstract life  can least  be attributed.   But by those whose
notions of Hunter's doctrines are founded solely on a perusal of the
posthumous " Treatise on the Blood" he is liable to be misconceived,
and in  opinions expressed from  that limited acquaintance with his
writings to be misrepresented.
   With the just ideas which  Hunter had acquired of the  laws
of vitality and  organic  heat he was enabled  to explain  many of
the  phenomena of digestion more satisfactorily than had  been
done by his predecessors Spallanzani and Reaumur.
   The* following  is  a fair example of the  different views and
Rinds  of  knowledge which these   experiments  brought  to  the
inquiry.                   .,,..,. i
   Spa'llanzani had observed that digestion did not  go on in rep-
tiles below a  certain  temperature,  he thought therefore that  heat

         * p. 158.                        t P. 162.
                                3 
18
HUNTER ON THE ANIMAL CECONOMY.
was necessary  to  assist  in  the dissolving processes of the sto-
mach ;  Hunter,  referring to  the  same  fact,   shows  that  the
influence here is not merely  chemical, but that the heat  operates
by  first  raising  the  sensitive  powers, these then  transmit  the
stimulus to the respiratory  and circulating  functions, and  lastly?to
the motive and other actions  and faculties,  and  that the  digestive
organs are necessarily excited to corresponding actions, in order to
supply the waste occasioned by the working of the machine, which
the heat has thus called into play.
  Hunter more accurately determined, and  first applied and render-
ed fruitful the fact which Grew incidentally mentions, viz., That it
is the property of a living body o-r part to  resist the action of the  .
gastric juice ; and his  celebrated  paper "On the  Digestion of the
Stomach after Death," is a beautiful example of the application of
his general view in physiology to the explanation of particular
phenomena.
   Of all  his published writing, the paper on  Digestion convey
perhaps the best idea of the extent of Hunter's researches in Com-
parative Anatomy, and of the soundness of his reasonings in General
Physiology.
   Hunter's claims  to  the  originality of observations which  have
been reproduced as new by late physiologists, I have pointed out in
the notes to these and other memoirs ;  and  have particularly endea-
voured to define the merit of  Hunter as a discoverer in reference to
 the absorbent system.
   Hunter's published  writings on the Nervous  System bear  but a
small proportion to the extent of  his anatomical  investigations on
this subject, especially as  they are manifested in the philosophical
series of preparations in the Gallery of his collection, in which the
 nervous system is traced  through its progressive stages of compli-
cation, from the simple filaments  of the entozoon  and echinoderm,
 to  the  aggregated masses which distinguish the  organization of
 man.   The fibrous structure of the brain, the discovery  of which,
 though due to Coiter as early as 1573, has sometimes been  attributed
 to  Reil and  Gall, is displayed by Hunter in preparations made to
 show the fact (Nos. 1335, 1336), and is expressly mentioned in the
 description of the Anatomy of the Whale  Tribe.*
    In treating of the comparative  anatomy of the nervous system in
 his introductory observations  to this  division  of  his  Collection,!
 Hunter rises to the following generalizations.  He divides the ani-
 mals which have brains, or visible aggregations of the nervous sub-
 stance, into six classes, each  characterized by a peculiar modifi-
 cation of the brain.
    The 'first class' has a brain in the form of a ring, through which
  passes the oesophagus, and from  which the  nerves arise, like radii
  from a centre.  It consists of a  pulpy substance, somewhat trans-
  parent, which is easily squeezed out when the brain is cut into.  It

         * P. 373.        f Physiological Catalogue, vol. iii., p. 4. 
PREFACE.
19
is not enclosed in hard parts, and is not defended from pressure or
injuries more than any other internal part.
  itie examples of this type in his Museum are selected from the
gastropodous class of Mollusca.  The same condition of the nervous
system  we now know, from the researches of Cuvier, to charac-
terize the whole of a vast division of invertebrate animals, including,
amongst the highest organized of  that division, certain species,—
the dibranchiate Cephalopods,—-in which the character, as expressed
by Hunter, is affected by the development of a cartilaginous cranium
lor the protection of the cerebral ring ; but ulterior researches have
not led  to any modification of Hunter's  description of the typical
form of the brain in the Molluscous sub-kingdom.
  In the 'second class'  the brain lies in the head of  the animals;
u 1>S ua  PU^y substance, somewhat transparent, which gives it a
bluish cast; from its lower part go out two large nerves, one passes
on each side of the oesophagus, and they then unite into one, form-
ing a  knot  at their  union; they disunite  again, and so unite and
disunite alternately through the whole length of the animal, at every
union giving  off the nerves  as from  the brain.   This  structure,
Hunter says, he suspects to answer both the use of a medulla spinalis
and the great intercostal nerve.
  The  examples of the class of animals adduced by Hunter  as
being characterized by this essential form of the  nervous system
are the leech, earthworm, aphrodita, centipede, caterpillar, scorpion,
and lobster.   Subsequent researches have shown  that it exists in
the barnacles, or Cirripedia, which most zoologists now rank in the
same  primary division with the Anellides, Insects, Arachnidans, and
Crustaceans.
  In the first class of animals  in this neurological arrangement (for
in enunciating general propositions respecting any given  organ the
comparative anatomist becomes involuntarily, as it were, a classi-
ficator of animals as well  as  organs), Hunter observes, " we had
the brain surrounded  by  soft parts only.  In the second  it was
closely surrounded  by soft parts, but these  were surrounded by
hard.   In the  'third class' the brain  has a case of hard parts for
itself, called the skull."
  Now when Hunter  made  a brain  relatively larger than  in his
first two classes—protected  by a skull,—and continuous  with  a
medulla spinalis extended  down  the back, and an endowment of
the five senses,—the essential neurological characters of his third
class  of animals,—he erred in not  applying them to his fourth, fifth,
and sixth classes, as an attribute common to all, and one which dis-
tinguished  each alike from the  two lower classes. The apprecia-
tion of the great natural group characterized  by a brain and spinal
chord, situated on the dorsal  aspect of the body, and protected  by
a  vertebral  case, was reserved for the  sagacious penetration of

   However, in so far as  Hunter  limits his  generalizations to the
brain alone, he is consistent with himself, and exact in the differential 
20
HUNTER ON THE ANIMAL CECONOMY.
characters which he points out.   The brain in fish, for example, or
his ' third class,' is a very irregular mass, inconstant in its form and
in the number of its parts ; still the " several parts which are similar
to those in a superior  class may be  picked out;" the skull, more-
over, is too large for the brain, and the interspace  is filled by a
cellular membrane, which Hunter compares to the arachnoid.
   In the 'fourth class,1 the  parts composing the brain " do not lie
one upon  another, but are very much  detached and follow  one
another," in short, are characterized by their linear arrangement;
a character, the accuracy of which, as applied to the Reptilia, has
been confirmed by all subsequent experience.   It is interesting to
observe  how Hunter determines the nature of these different de-
tached masses.  He says, " The two anterior  consist of  the cere-
brum ;  the two  middle, I should suppose, of the nates and testes,
which  I take to be the middle lobes  detached, because in the bird
they are more  underneath, not so much between the cerebrum  and
cerebellum ; the posterior is the  cerebellum, consisting of one body
entirely."*  Every eminence, Hunter further observes, has a cavity
or ventricle in  it.   The  linear  arrangement of the  masses of the
brain  is common  both to fishes and reptiles; but the relation of
those masses to the skull, and their variable number  and propor-
tions, according to Hunter, distinguish the brain in fish.   He further
observes that in the crocodile the parts of the brain are more closely
connected, and that the skull is  more in contact with it,  in which
respect it comes nearer the bird  than  do any of the other amphibia.
   The brain  in  the 'fifth class,' or fowl, Hunter  characterizes  by
its  greater relative  size, and the superposition of its component
masses.
   In the ' sixth class' or quadrupeds, the brain is in general larger
than in the preceding, and the  parts more compacted, the whole
mass being brought into nearly a globular figure.   " The nates  and
testes are four  small bodies, with no visible cavities; are not seen
externally, but lie at the posterior end of the third  ventricle."t
   In the observations printed in  the present volume on the  branches
of the fifth pair which are distributed to the nose  and ear,  we can-
not fail to observe that Hunter had entered on that track of inquiry,
and perceived the governing principle or idea, which, more clearly
appreciated and steadily retained by Sir Charles Bell, has since led
to such important improvements in this department of physiology.
   Hunter premises  his description of  the nerves which supply the
organ of smelling by calling attention to the constancy which per-
vades the anatomical conditions  of the nerves, and states in general
his belief that particular nerves have particular functions, in relation
to their  differences  of origin, union, and distribution ;J  but  this
simple enunciation, without the proofs and illustrations of  which it
was susceptible, became  unproductive  of  its proper  results,  and
appears to have been subsequently lost sight of by Hunter himself,
  * Physiological Catalogue, vol. iii., p. 7.       + Ibid  p 10
  X Pp. 204, 205. 
PREFACE.
21
when speculating  on the nerves as internuntiate  conductors of a
materia vitce diffusa.
  A knowledge of Hunter's opinions on the nervous system, derived
only from  the  observations on  that  subject which occur  in the
Treatise on the Blood, might lead to the belief that he attributed to
all the different  nerves  one common function ; but after  perusing
the distinct exposition of his views on this branch of physiology as
recorded in the  Animal  (Economy, it appears  to  me that Hunter
needed only to  have resorted to experiment  in this, as he  did so
successfully in other fields of  physiological inquiry, to  have esta-
blished the nature and degree  of the functional  differences of these
nerves, of which he describes the anatomical  conditions giving rise,
as he supposes, to those differences.
  He limits himself, however,  in his illustration of the grand propo-
sition, by anatomical examples only.  He  shows that  organs like
the eye and nose,  which are endowed by means of one nerve with
a special sense, derive their ordinary sensation from a second nerve
having a different origin.  This nerve he  determines, in  the case
of the eye and nose, to  be  the fifth pair.   He says the same mode
of reasoning is  equally applicable to the organ of taste, and  he traces
the corresponding superadded  nerve to the ear.
  Hunter further distinguishes the sensations of the stomach and of
the glans penis  as  being peculiar, and shows  that as these peculiar
sensations reside in particular  nerves, so at whatever  part  of the
nerve the impression is  made it always gives the same sensation as
if affected  at the common  seat  of  the sensation  of that  peculiar
nerve.
  In another place Hunter  makes  the ingenious  remark  that the
nerves which are specially designed to receive peculiar impressions
convey the ideas of such impressions to the brain, in whatever way
they may be affected or stimulated.   Thus he says, " A mechanical
impression on the retina  produces an impression  of light; a blow
on the ear the  sensation of sound."*  And later experiments have
only extended this principle, by showing that whether the  nerve be
affected by mechanical, chemical, or electrical stimuli, it  conveys
the same sensation.
  Much  importance has been  attributed to these  observations, on
the supposition  that  they were new, and I have  been  induced to
dwell thus  long upon Hunter's  contributions  to the physiology of
the nervous system, because in most of the recent works upon that
subject  he does  not receive  the credit  which is  due  to him for

 mThe  physiological discoveries of Bell, Magendie,  Mayo, and
Muller  have resulted from the  combination  of experiment with a
ohilosophical consideration of the anatomical peculiarities of the
nervous system.   It was the neglect of experiment  in th.s  depart-
ment of physiology which  rendered Hunter  unable to  account for
  ♦ Lectures on Surgery, p. 56-7, of the; present edition, and Parkinson's Hun-
terian Reminiscences, p. 12.
                               o* 
22
HUNTER ON THE ANIMAL CECONOMY.
the peculiarities which equally struck his mind as being connected
in an intimate degree  with the functions of the nerves.
  Had Hunter combined experiment with dissection when he traced
the lateral branch of the nervus vagus in the cod, the eel, and the
gymnotus, and wondered " that a nerve should arise from the brain
to be lost in  common parts,  while there  was a  medulla  spinalis
giving nerves to  the  same  parts," this probably  would not have
remained to him, as he expresses it, " one of the inexplicable cir-
cumstances of the nervous system."*
   Having been induced to dwell on  the  improved views which
Hunter either established or suggested in  different  branches  of
physiology, I proceed next to advance a few instances of his dis-
coveries in  comparative anatomy, which, on the supposition that
they were original, have  contributed  to add  to  the reputation of
subsequent anatomists.
   1.  The organ of hearing in the sepia.   The fact that this cepha-
lopod possesses the organ  in question is stated  at p. 300 of the
present edition of the Animal (Economy, and it  is said to  differ
from that  of fishes.  The discovery is  attributed by  Cuvier  to
Scarpa.
   2.  The semicircular canals of the Cetacea, described by Hunter
in the  paper on whales, a  structure which  Cuvier rightly  states
that Camper overlooked, but incorrectly claims the  discovery as
his own.
   3.  In the latest sketch of  the  history of  comparative anatomy,
prefixed to the French translation of Carus's Zootomie, John Hunter
is introduced as the  impudent self-appropriator  of Camper's  dis-
 covery of the air-cells in the bones of birds; and the  historian of
 the science does not honour  him with any further notice.
   Now  the facts with reference to this subject are  as  follows :
Camper's account of the air-cells in the  bones of Birds was first
published in  the Dutch language in the year 1774, the  same year in
which Mr. Hunter's discovery was published in  the Philosophical
 Transactions.  The French memoir of Camper was  not published
 till the year  1776, in  the seventh volume of the  Memoires Etrang.
 de l'Academie des Sciences de Paris.  Hunter gives the date of his
 discovery as being in 1758;  Camper his, in the year 1771.
   The numerous observations and experiments which their respec-
 tive  memoirs detail are not  such as could hastily be got  up for an
 unworthy purpose ;  but as both memoirs (which differ materially in
 their general scope and the  mode in which the subject is treated)
 were published in the same  year, the honour of the discovery may
 fairly be attributed to both their authors.
   I might dwell on  the  philosophical  comparison which Hunter
 makes between the abdominal air-cells of  the  bird  and those of
 reptiles and  fishes had he not in this instance  been anticipated by
 Harvey.  Harvey, however, was not aware that the respiratory
* Animal CEconomy, p. 412-13. 
PREFACE.
23
system was extended into the muscular interstices and the cavities
of the bones; the honour of which discovery must  be assigned to
Hunter and Camper, without the necessity of supposing that either
had borrowed from  the other.
  The preparations  in the Hunterian Collection and the Manuscript
Catalogues show that Mr. Hunter had discovered  the  peritoneal
canals or openings in the eel, salmon, and the  cartilaginous fishes,
in the crocodile, and the continuation of the same peritoneal canals
into the corpus  cavernosum penis in the tortoise and turtle.  The
latter have been recently rediscovered by MM. Isidore  St. Hilaire
and Martin St.  Ange.
  Hunter's printed works, preparations, manuscripts and drawings
contain proofs of  his discovery of the  circulation  of the blood in
insects, and of the peculiar diffused irregular and extended venous
receptacles in these  and the crustaceous animals,  in the latter of
which their existence remains unnoticed,  even  in the latest works
on the subject.
   In the Treatise on the Blood* we have an opportunity  of judging,
by  the accuracy of  the  general propositions which he enumerates
on this subject,  of the extent of Hunter's  researches on the  com-
parative anatomy of the circulating system, and  of the spirit in
which he prosecuted the induction  of  particular facts.   I cannot
resist the quotation  of the following passages  which relate to the
circulation in insects.  " In the winged insects which have but one
heart, as also but one circulation, there is  this heart answering both
purposes" (viz., the corporeal  and  the  pulmonary circulations),
p. 172.
   " Many of those which have one ventricle only have no auricle,
 such as insects  ; but there are others which  have both  a  ventricle
 and auricle, such  as fish, the  snail, and  many shell-fish; some of
 the last class have indeed two auricles, with only one ventricle.—"
   The heart " is placed  in what is called the chest in the  quadruped,
 bird, amphibia,  fish, and the aquatic and  terrestrial insect, but not
 in what mav be called the chest in the flying insect.
   " The chest in  the aquatic  insect seems best suited to  contain the
 lungs  and branchie, and therefore the heart is placed there; but as
 the lun.^s of the flying insect are placed through  the whole  body
 of the heart is more diffused, extending through the whole length of
 the animal." p.  174.
   " Where the veins entering into the heart are small in comparison
 to the quantity  of blood  which  is wanted in the ventricles, then we
 have an  auricle ; but when the  veins near to the heart are  large,
 there is no auricle,  as in the lobster and generally in insects." p. 176.
   " In all animals which have an auricle and  a ventricle, so  far as
 I know  there is a bag (unattached) in which they are placed,  called
 a pericardium  ; but the insect tribe, whether aerial, aquatic, or ter-
 restrial,  have none, their  hearts being attached to the surrounding
 parts by the cellular membrane or some  other mode of attachment.
* § 5., p. 171 of the present edition. 
24
HUNTER ON THE ANIMAL CECONOMY.
   The heart " gives to the blood its  motion in most animals, and
in all it sends the blood to the organs of  respiration ;  in the flying
insect it sends  the  blood  both  to those organs and  to the body at
large, but in fish  to  those organs  only, the body at large in them
having no heart.   In the  amphibia  there  is  an attempt towards a
heart both for the lungs and  body, but not two  distinct hearts.   In
the bird and quadruped there is a  distinct  heart for each."  And
again, " With respect to its use, it is  in the most simple kind of heart
to propel the blood  through the  body  immediately from  the veins,
which blood is to receive its purification in this passage when  the
lungs are disposed throughout the body as in the flying insect." p. 179.
   The researches of Cuvier led him to conceive  that there was
a generally  diffused, but passive, or  non-circulated condition of the
blood, coexisting in  insects  with the  distribution of the  breathing
organs through the whole body.  Hunter, on  the contrary, while
he rightly appreciated that condition  of the circulating system in
insects which  related  to  their  peculiar respiration, viz., that  the
venous blood was diffused apparently through the cellular membrane,
in the interstices of the fat, air-cells, and muscles, and that the veins
in insects might be called  in some  measure the cellular membrane
of the parts;* yet he well knew the relations of these diffused  re-
ceptacles of the venous blood to the dorsal heart, and the circulatory
movement which was impressed upon the vital  fluid by that organ.
It is this remarkable error of Cuvier, with reference to the circula-
tion in insects, that has  given to  the  direct observations of  the
blood's motion by means  of  the microscope in the hands of Carus,
Bowerbank, and other excellent observers, the character of a new
discovery.
   Hunter first determined the bi-auricular structure of the heart in
the batrachian caducibranchiate  reptiles, which he included in  the
class Tricoilia of  his  classification of  animals according to  the
structure of the heart.
   Hunter first discovered, by means of retrograde injections of  the
tubuli uriniferi, that these  essential  partsof the  kidney extended to
the superficies of that gland, and were not confined to the medullary
substance.   Meckel, who saw  while  in London the  beautiful pre-
parations establishing this fact (Nos. 1202,1203, 1214, 1215, 1235),
described them on his  return to Germany to Miiller,f who, in  his
recent elaborate work  on the glands, acknowledges how important
this observation was in establishing true notions of  the  structure
of glands.
   Hunter extended his researches on  the renal  organ to the inver-
tebrate classes, and shows " the kidney of the snail;" and the cor-
rectness of  this ascription to the  so-called  mucous gland has been
recently established by the observations of Professors Jacobson and
de Blainville.
  * See Physiological Catalogue, ii., p. 31 ; also the note at p. 221, vol. iii., of
the present edition.
  f De penitiori structural Glasdularum fol. p. 95. 
PREFACE.
25
  I have selected a few facts from amongst the  multitude which
liunter ascertained in the progress of those investigations, by which
he sought in the simpler modifications of the structures in the lower
animals the true uses  of the different organs which  are combined to
form the complex frame of man.
  I might lastly allude  to  the extraordinary  nature and extent of
Hunter s labours in another track of physiological inquiry, viz., that
which unfolds the laws of generation  and animal development; but
as the  work confided to me by the Council of the Royal College
of Surgeons, viz., the description of the  series of  preparations on
these subjects, which include nearly  one-half of Hunter's grand
Physiological Collection, is still in progress, I  defer the comparison
of Hunter's labours  in  this field with  those of his  contemporaries
until the wmole body  of the evidence of his discoveries  can be laid
before the public.
  The papers, however, which Hunter published in his lifetime, and
which form the first  part  of the present volume, convey a most
favourable idea of his views  respecting  this recondite branch of
physiology.  It is here  that we find an attempt to explain congeni-
tal defects by reference to  the transitory structures or metamorpho-
ses of foetal life.
  It was a question in the  time of Hunter how it happened that the
gut in  the hernia congenita came to be in contact with the testes.
Hunter solved the question, by directing attention to the position
of the  testis in the abdomen, and to its relations to the other abdomi-
nal viscera, and to the peritoneum, a  few months, before the expi-
ration of the term of foetal  development.   He watched the progress
of the gland to the scrotum ;  saw it carrying  along with it a perito-
neal pouch like the sac  of  an intestine, and thus demonstrated, that
if the closure of that sac  was prevented by the contemporaneous
passage ofa loop of intestine, it  must remain a common receptacle,
both of the part which had naturally, and the part which  had  pre-
ternaturally, escaped from  the abdomen.
  Hunter then goes on  to show  how the  early and transitory  con-
dition of the tunica vaginalis in the human foetus, and also the still
earlier abdominal position of the testes, are permanent structures in
the lower mammalia.
   With respect to monstrosities in  general, Hunter had drawn out
a scheme for their classification, and had  produced them by experi-
ment.  In the " Account of an  extraordinary Pheasant" he states
that every species of animal, and  every part of an animal body, is
subject to congenital malformation ; but he knew that such appear-
ances  were not attributable  to a freak of Nature, or a matter of
mere chance;  for he observes that every species  has a disposition
to deviate from Nature in a manner  peculiar to  itself.  It is this
principle which forms the basis of the latest and most elaborate
treatise on monsters,* a work which its author describes as being

  * Histoire des Anomalies de l'Organization chez l'Homme et les Animaux, ou
Traite de Teratologic, par Isid.  GeofTroy St. Hilaire:  Paris, 8vo. 1832. 
26
HUNTER ON THE ANIMAL CECONOMY.
"the  result of his  having established  by a great number of re-
searches, that monsters are, like the beings  called normal, subject
to constant rules."
  With respect to the cause or origin of monsters, Hunter referred
it to a condition of the original germ, or, as he expresses it, "each
part of each species seems to have its  monstrous form  originally
impressed upon it."   ]n the introductory observations to  his exten-
sive collection of  malformed foetuses and  parts, he assigns the
grounds for this hypothesis, and at the same time enunciates one of
the most  remarkable laws of aberrant  formations.   " I should
imagine,"  he writes, " that monsters were formed monsters from
their  very first formation, for this reason, that  all supernumerary
parts  are joined to their similar parts, as a head to a head, &c, &c."
In  proof of the important general principles, at  a  knowledge of
which Hunter had arrived, I  have elsewhere quoted this passage,
together with the following remarkable  one from Hunter's descrip-
tions  of his drawings illustrative of  the  development of  the  chick.
" If we were capable of following the progress of increase of ihe
number of the parts of the  most perfect  animal, as they first formed
in succession from the very first, to its  state of full perfection, we
should probably be able to  compare it with some one of the incom-
plete  animals themselves, of every order of animals in the creation,
being at no stage different  from some of those  inferior orders; or
in  other words, if we were to  take a series of  animals  from the
more imperfect to the perfect, we  should probably find an imperfect
animal corresponding with some stage of the most perfect."*
   We may, I think, perceive, from the evident difficulty with which
Hunter expresses the idea,  that his  mind was oppressed with both
its  novelty and vastness.   Men's  thoughts require to be familiar-
ized with  propositions of such generality before  their exact limits
and full application can be appreciated.
   Sufficient, however, has  been adduced to prove the tendency of
Hunter's  labours, and that he  possessed  the highest qualifications
as  an investigator of Nature ;  unwearied in induction, sagacious in
grouping  together  analogous  phenomena, and  ever striving to
ascend from propositions of less to those of greater generality.
   Had the means and time been  granted to Hunter  to have made
public the results of all his  labours, or had his manuscripts enuncia-
ting,  or indicative of, so many general principles been fairly appre-
ciated and given to the world, our teachers of anatomy would not
now,  after a lapse of half a century, have but begun  to  explain to
their  students those beautiful  laws of animal development, for the
knowledge of which they are indebted  to the labours of the profes-
sors in the noble schools of physiology in Continental Europe, where
the spirit of Hunterian inquiries seems to have  so long exclusively
resided.  But the  period which has elapsed before those general
laws  began to be appreciated in the country where they were first
detected, affords,  perhaps,  one  of the strongest indications of the
great  advance which Hunter had  made  in physiological science.
        * See preface to the Physiological Catalogue,  vol. i. p., ii. 
PREFACE.
27
  It would be a strange exception to the  usual result of an exten-
sive knowledge of comparative anatomy, combined with a tendency
to express m general propositions new physiological and structural
truths, if the possession and application of'that knowledge with that
tendency had so led  to some corresponding advance  towards a
natural system of zoological  classification.   Accordingly we find
the contemporaries of  Hunter  ascribing to him the highest  ac-
complishment which the zoologist can aspire to, that of discerning
the natural affinities ofa nondescript object; and this in terms and
on occasions which seem to imply a general admission of  his pos-
session of such attainments.  When the rare quadrupeds of Austra-
lia were first  brought to  England, presenting,  as they did, to  the
eye of the zoologist anomalies  and peculiarities not less striking than
those which perplexed the botantist in the plants from the same part
of the world, it was to Hunter that they were referred.
  " There was  no  person," says Dr. Shaw, " to whom they could
be given with so much propriety, he perhaps being most capable of
examining accurately their structure, and making out their  place in
the scale of animals."*
   It may not be uninteresting to  contrast the sketches of  systems
of zoological arrangement which Hunter has left, with the Linnean
method which prevailed in his time, and which continued to prevail
until superseded by the  labours of Cuvier, specially and unremit-
tingly directed  to that end.   We have already seen that Hunter's
attempts to  enunciate general propositions  respecting the  nervous
system led  him to  detect the condition characteristic of the mol-
luscous sub-kingdom, and to speak of the animals with  " the brain
in the form  of a ring, " &c, as a class.  In still more definite terms
he describes the condition of the nervous system which characterizes
the articulate Invertebrata.
   With respect  to that higher  type of the nervous system, which
 is manifested in its aggregation into spinal and cerebral masses,
 we have seen that Hunter  alludes to it as distinguishing  only the
 class of fishes from his first  and second classes, or the Molluscous
 and Articulate divisions as they are now termed ; and that he failed
 to perceive that all the other vertebrate classes were equally charac-
 terized  by  it.   To Hunter, however, we must award the  merit of
 having first obtained  a perception of the distinct group formed by
 the higher organized vermes  of Linneus, and their essential organ-
 ical  character.   Hunter had  also  investigated the structure of
 zoophytes,  in which  no  annular  brain can be  detected ;  he  had
 conceived  the  idea of animals in  which the  nervous  matter, or
 something  analogous to it, a materia vitce diffusa, was dispersed
 throughout  the  system.  And  we  find  another learned  contem-
 porary of Hunter,'in ascribing  a  diffused condition of  the nervous
 matter to the Tenie, bearing testimony that Hunter had entertained

   * Zoological Appendix  to White's Voyage to New South  Wales, p. 468 of
 the present work. 
28
HUNTER ON THE ANIMAL CECONOMY.
a similar opinion, and  had applied that character of the nervous
 system to many of the lower tribes of animals.*
  The distribution of animals according to the nervous element of
their organization's, however, but one of several attempts at classi-
fication which Hunter made.   The  next scheme which we  shall
quote is one founded upon modifications of the generative function.f
Hunter's first class, or Vivipara, corresponds  with the  Zootoka of
Aristotle, and the  Mammalia of Linneus; these  animals  develop
their  young in the uterus, he  says, from a  mixture of  male  and
female influence, and bring forth a living offspring.
  The second class, or Ovovivipara, is a subdivision of the Ootoka
or Ovipara of Aristotle, and  "hatch  their  young from  an  egg in
the oviduct, as vipers, slow-worms, some  lizards, newts, and the
dog-fish."
  The third class includes the Ovipara, or " such animals  as exclude
their  eggs, which  are afterwards hatched out of the body ;" but
this character, as Hunter justly observes, " takes in a wide field."
  Fourthly,  he says,  " We have animals which propagate by slips,
and that  in two different ways, one by a piece cut off, the other by
 branches growing, and these falling off, and producing  a  distinct
animal."  Hunter here rightly regards the fissiparous and  gemni-
parous modes of generation as modifications of the same reproduc-
tive process which is characteristic of that  lowest group  of animals
previously  indicated  by the molecular condition of the nervous
system, and " where every other principle  of the animal is diffused
through  the whole," a condition which in the  animal kingdom
seems essential to the possession of the property of fissiparous re-
production,  or to a division of the whole body with a continuance
of the vital properties in the parts.  Hunter seems, however, to have
 felt how  unsatisfactorily and artificial was the classification founded
 on modes of generation, for he  adds  in the  manuscript in which the
 above sketch  is given, " Animals of any particular class have not
one way only of  propagating  their  species,  excepting  the more
 perfect, or first class according to hearts,  for we have the  second
 and even the third class  aping  the first, and  attempting  to be vivi-
 parous, as vipers, lizards, and some fishes, as the skate."  He might
 have added examples of ovoviviparous animals, from the molluscous,
 articulate and radiate classes,—classes which  in  every other re-
 spect are most dissimilar.   This idea of  an arrangement of the
 animal kingdom from modifications of the  generative function  was
afterwards carried out by Sir Everard  Home,J and applied by him
 to the definition of the narrower or subordinate  groups.  But as of
 all single characters the generative system affords the most arbitrary
 and unnatural distinctions, and  corresponds least with  the  modifi-

  * See Carlisle, On the Structure and CEconomy of Taeniae, Linnaean Transac-
 tions,  vol. ii.,  p. 253, and Treatise on the Blood, p. 116, of the present edition.
  X See Introduction to the Physiological Catalogue, vol. iii., p. vi.
  X See his Systema Regni Animulis  nunc primum ex ovi modificationibus pro-
 positum, Lectures on Comparative Anatomy, vol. iii., p. 535. 
PREFACE.
29
 wLT °f the- r?st of the  organization, a  classification of animals
 cased upon it is least adapted to afford any of the conveniences of
 even an artificial system.

 wh^l!hthSy*'e"ia JVatur<B of Linneus the first of the characters by
 m^-fi   ?• SIX Ciasses of animals are distinguished is derived from
 modifications of the structure of the heart, as follows:

              " Mammalia,  Cor biloculare, biauritum ;
               Aves, Cor biloculare, biauritum ;
               Amphybia, Cor uniloculare, uniauritum;
               Pisces, Cor  uniloculare,  uniauritum;
               Insecta, Cor uniloculare, inauritum;
               Vermes, Cor uniloculare, inauritum."

 But Linneus combines the cardiac  character with others derived
 from the nature of the blood, the condition of the respiratory organs,
 the structure of the mouth  and generative organs, the nature of the
 integuments, &c., and thus makes an approach to a natural system
 of  arrangement.
   Hunter, in his distribution of animals  into different  classes ac
 cording to the structure of the  heart, uses  the  cardiac character
 singly,  and  produces a purely artificial arrangement;  but  his
 superior anatomical knowledge  manifests itself in the accuracy
 with which  he  defines the  condition of  the  circulating  organ
 characteristic of the different groups.
   His^rs* class  includes the Mammalia and Aves of Linneus, and
 he  proposes to call it Tetracoilia, the heart having four  cavities,
 viz., two ventricles and two auricles.
   The second class, Tricoilia, includes those animals which \iave a
 heart with three cavities, viz., one ventricle  and two auricles, and
 corresponds with the Amphibia of Linneus.   The anatomical inac-
 curacy in the Linnean character, although  so  early corrected by
 Hunter, long retained its ground in the systematic works  of conti-
 nental naturalists, and continued to be erroneously applied to the
 Batrachian section of the Linnean Amphibia until  a very recent
 period.*

  * The two auricles were after the time  of Linnaeus successively assigned in
 systematic works to the  Chelonia and Sauria.  Blumenbach long continued to
 assert that serpents, at least those of Germany, had but one auricle ; Cuvier al-
 lowed them two, but denied this  higher structure of the heart to the Batrachia :
 " lis n'ont au cceur qu'une seule oreillette et un seul ventricule." Regne Animal,
 ii., p. 101, edit. 1829.  Meckel also  ascribes this structure to  the generality of
 the  Batrachia:  "Die  Batrachier haben die einfachste Herzform. Das Herz
 besteht sehr allgemein nur aus einer Vorkammer und einer Kammer."  Vergl.
 Anat., band v., p. 215.  The more complicated structure of the heart was, how-
ever, truly described in the anourous Batrachia  by Dr. John  Davy  in 1825 ; his
 observations were confirmed  by Prof. Weber  in  1832; and in April, 1834, I
communicated to the Zoological  Society the  result of a series of examinations
of the hearts of  the Batrachia, which proved that the whole order, including the
perennibranchiate species, had distinct auricles for the pulmonic and  systemic
blood, since which time the tripartite structure of the heart has been universally
assigned to the Batrachia.
                                    4 
30
HUNTER ON THE ANIMAL CECONOMY.
  The  third  class,  or Dicoilia, includes those which have  two
cavities in the heart, or one ventricle and one auricle, and consists
of the gill-fish.   The sharks and rays  were included by Hunter in
this class, but the diccelous or bipartite structure of their heart pre-
sented  no  obstacle  to their junction  with the Amphibia  in  the
Linnean arrangement.
  Hunter's fourth  class, or Monocoilia, characterized  by a heart
with but one cavity or ventricle, without an auricle, is  restricted to
insects of all kinds, i. e. to the articulate animals included by Hunter
in his second class according to brains.
  By Linneus the character is applied to all invertebrate animals
without exception.   Hunter,  with more truth, defines  a fifth class
of animals, by the name  of Jlcardia, " whose stomach and heart
are the  same body, as in the blubber (Medusa) and polypus."  But
even with this improvement, the Cardiac arrangement of animals,
as proposed by Hunter, is very incomplete.  The whole division of
the molluscous animals is  left out of the system.  This did not,
however, arise from a want of the knowledge  of  the  structure of
the  heart in those animals.   Hunter well knew the complex  condi-
tion of the circulating  organ  in the cuttle-fish, a condition which,
had he rigorously carried out his scheme of classification according
to hearts, would have indicated a class above the  mammalia, and
to which the name of Heptacoilia might have been  applied, since
there are three distinct ventricles, one  systemic and two pulmonic,
and four auricles or venous sinuses in this and  other  dibranchiate
cephalopods.  In the snail and other gastropods Hunter had recog-
nised a  structure of the heart as complex and perfect as in fish, but
having a different relation, both as regards function and position, to
the respiratory organ.*  In still lower Mollusca Hunter had detected
the existence of two distinct auricles, with one ventricle ;f  but  his
perception of the physiological relations of these different cavities
prevented him from associating the mussel  with the  tortoise, on
account of  this  triccelous structure of the heart.   We may thus
perceive amidst the defects  of this system of arrangement an evident
advance towards a more natural distribution of animals, especially
of the invertebrata, than that  which was generally accepted at  the
period when  Hunter  wrote.   We associate this  progress with
Hunter's superior knowledge of the  organization  and  ceconomy of
animals as its just  and natural cause, and  we proceed to  adduce
additional evidences  of Hunter's  attempts  to  frame a  natural
arrangement of animals.
  Perceiving that the modifications  of the  heart alone were  inade-
quate to the formation ofa  natural  and symmetrical classification
of animals, he next tested the efficiency of characters  taken from
conditions of the respiratory  system, and  proposed the following
scheme:
  " The first class includes all those  animals which have lungs with
cells through the whole, and a diaphragm.
       * On  the Blood, vol. iii., p. 172.           f Ibid., p. 172. 
PREFACE.
31
     The second class, all those which have  their lungs  attached to
 the nbs, so as to confine them to their place.

 are loose          ' &U th°Se wh°Se lungs Come into  the belly and
   " The fourth class, all those whose lungs are in their necks, called
 gills.                                 °
   " The fifth class, all those whose lungs are in  their  sides."*
   In this scheme we have most exact and concise characters of the
 four classes of vertebrate  animals, as  afforded  by the breathing
 organs; and in this  case Hunter  was  enabled by his profound
 anatomical knowledge to rise far above Linneus.
   In the Systemce Natures, the Mammalia and Aves, which  corres-
 pond with Hunter's first and second classes, according to the organs
 of respiration, have both the  same characters  assigned to them,
 " pulmones respirantes reciproce," while the Amphibia, to which
 Hunter's  third  class corresponds,  are  said by  Linneus to  have
 " pulmones spirantes  arbitrarie."   Neither Hunter nor Linneus,
 however, arrived at the perception  of that condition of the  respira-
 tory organs which characterizes their first four classes in common,
 viz., that the breathing organs  communicate with the mouth; nor
 am  I aware that the  Vertebrata have ever been distinguished in
 any system as oral breathers, in contradistinction to the Mollusca,
 which may be termed anal breathers, and to the  Articulata, which
 respire by apertures or branchial  organs arranged symmetrically
 at the sides of the body.
   We have  thus traced Hunter in  his character as  a systematic
 zoologist  through a  series of attempts at  the arrangement of the
 animal kingdom, in which, like the indefatigable Adanson in a sister
 science, considering each  organ by itself, he  formed, by pursuing
 its various modifications, a  series of groups characterized  by  that
 organ alone ; and doing the same for another organ and another,
 thus constructed a collection of systems of arrangement, each  arti-
 ficial, because each was  founded upon the variations of a single as-
 sumed organ.
   It would, however, be doing  injustice to  Hunter to adduce  the
 evidences of these attempts only.   In that  division of the  animal
 kingdom where he had pushed his  researches furthest, he aims to
 establish a more natural  classification, by tracing the  variations of
 all the important organs, and keeping in view the different value of
 each character; and thus he enunciates several general anatomical
 and  physiological truths.  The  following are the characters which
he assigns to the different classes of the animals now called  Verte-
 brate.
  " The properties of the First  Class, which includes both sea  and
land animals, are
  "Heart,  made up of four cavities, essential.
  " Lungs, divided  into small cells, and confined to a proper cavity,
* Physiological Catalogue, Introduction to the Third Volume, p. v. 
32
HUNTER ON THE ANIMAL CECONOMY.
     the enlargement of which is the cause of respiration ; essential,
     Respiration quick (and I believe this is the only class in which
     it is so); essential.
  "Give suck; essential.
  " Parts of generation, made  up of testes and one penis in the
     male ; the testes sometimes  within and sometimes without the
     abdomen,  but  pass forwards.  Clitoris, vagina,  uterus  or
     uteri, Fallopian tubes, and  ovaria,  in  the female: all es-
     sential:
  " Kidneys, high up in the  abdomen; circumstantial.
  " Organ of hearing, an external canal to the ear,  membrana
     tympani concave externally,* a cochlea ; circumstantial.
  " The animals of this class are by much  the most perfect, whether
     sea or land.   There is a  gradation  from the land to the sea
     animals, viz., otter,  seal, hippopotamus, whale.
  " The Second Class is  confined to the  Birds entirely.  I do not
know of. any animal of this class but what  has all the characteristics
of the  bird.  They vary less in any of their parts than the first
class.f
  " Lungs, attached to the  ribs,  that they may move with them:
     lungs perforated; membranous bags in the abdomen that re-
     ceive air in respiration; something  like a diaphragm.
  "Parts  of generation, ova crustaceous ; one oviduct; one penis,
     and  that grooved;  no bladder.  Oviduct  in the female, and
     penis with the vasa deferentia in the male, all open in the
     same cavity with the anus.
  " Liver, divided into two lobes ; cyst-hepatic ducts.
  " Organ of hearing, little external passage to the ear ;  membrana
     tympani convex externally, but one bone (ossiculum auditus);
     no cochlea.
  "Feathers; wings; two legs;  long neck; bill; membrana nic-
     titans; bursa Fabricii.
  "There is none of this  class that belong entirely to sea  animals;
     but this class may  be said to possess in some  measure three
     elements, viz., air, earth,  and water; but they live  no more
      in the air than other animals, for it is only for their progres-
     sive motion.
  " In  the Third Class we shall find some parts similar to the second.
     The third class may be  divided  into two, for they are not
     exactly alike, but one seems to partake of the second and
     third ;  as it were, made up  of both.'  The first division  of the
     third class, then, is  the Lizard and Serpent  kind.  They have
  " Heart, two auricles, one ventricle, two aortas which unite in the
      abdomen.

  * This appears to have been  written before Mr. Hunter had dissected the organ
of hearing in the whale.   See p. 380, and note*.
  f So  also Cuvier: "De toutes  les classes d'animaux, celle des  oiseaux est la
mieux  characterised,  celle dont les especes se ressemblent le plus."__Regne
Anim.,  i. p. 310. 
PREFACE.
33
   " Lungs, loose bags, which lie in the thorax and abdomen, only
partially divided.   No diaphragm.
   ^ Kidneys, in the lower part of the abdomen.   No bladder.*
   "Parts of Generation, two penises, grooved,! which are in the
      tail.   Some oviparous, eggs without shells; others viviparous,
      but not as the First Class.
   " Some have  legs, others none;  some  a  membrana  tympani,
      which is convex outwardly, as the lizard; others none, as the
      snake.
   " The other  part of this class, which may be termed the Fourth,
or the Amphibious, are more closely allied'to Fish than  what the
fish of  the first class are.J  These are  the  common amphibious
animals, viz. frogs, turtles, efts, &c.   This is also very similar to
the two former, artd  is nearly, as it were, a  mixture  of  both, yet
the most essential parts belong, or are similar to the last.
   "Heart, two auricles, as in the Third ;  one ventricle,  as in the
       Third;  aorta, as in the  Third.
   " Lungs, as  in the Third.
   " Kidneys, as in the Third.
   "Part of generations, one penis,  as in the  Second Class;  penis
      grooved, as in the Second and Third.  Some oviparous, as the
      frog; others vivaparous  as the salamander.
   " Organ of Hearing, some have  a membrana tympani, as the
      frog ;  others  none, as the tortoise.§
   " The Fourth or Fifth  Class (according as the two preceding
are regarded as subdivisions of one class, or as two distinct classes)
consists of Fishes,  and is very distinct from the former so far as I
know."

   The manuscript  from which the preceding remarkable  passages
are quoted,  and which is  printed entire in my Prefatory  Observa-
tions  to the  Third Volume of the Physiological Catalogue, contains
no characters of the Class of Fishes,  nor any relating to the Inver-
tebrate Classes.  It is in the definition of these  latter  classes, and
in the determination  of the wider divisions  of  the Invertebrata,
which were equivalent to the entire vertebrate group,  that  Cuvier
chiefly surpassed Hunter as a systematic zoologist.  Yet, as I have
before observed, Hunter rises above  Linneus even in  this  depart-
ment: he had seized  the  great character of the molluscous sub-
kingdom afforded  by the nervous system, and had well defined some
of the subordinate groups, more especially that which  Larnarck
afterwards  termed  Tunicata,  and  which   Cuvier  denominates

  * This character is not applicable to the lizards ; but the crocodile agrees with
the serpents in having no urinary bladder.
  + The crocodile has  but one.
  t *.  e.  Those of the first class which are shaped like fish, and live in water,
as the  Cetacea.
  § The turtles and tortoises, or Chelonian reptiles, as they are now termed, have
a closer affinity to the lizards than to the Batrachia, or frogs and salamanders.
                                4* 
34
HUNTER ON THE ANIMAL CECONOMY.
 " Aciphates sans Coquilles," but which Hunter,  more  correctly,
 termed " soft-shelled," having perceived the analogy of their  ex-
 ternal elastic tunic to shell; and having detected, with admirable
 skill, the relations subsisting  between  the  Ascidie and  Salpe in
 different individuals  dissected by him, of which dissections there
 remain not only the  preparations, but several beautiful designs,
 with the original descriptions.*
   Of Hunter's appreciation of the progression of affinities we have
 an example in his sketch of the transition from the terrestrial to the
 aquatic Mammalia;  and I do not doubt that ere  long zoologists
 will uniformly agree in the propriety of passing from  the hippopo-
 tamus and its pachydermatous congeners to the dugong and the true
 Cetacea, instead of interposing the Ruminantia between the Pachy-
 dermata and Cetacea, as in the Cuvierian system.
   Of his mode of considering the affinities of two great and equal
 groups, Hunter has left the following specimen, which  he quaintly
 designates " Of  the similarity of the Fowl with the three-cavity-
 hearted gentry, called Amphibia."
   " The lungs of the fowl open into their  air-cells or bags that
 are in the cavity of the belly.  The lungs in the Amphibia are con-
 tinued into the belly, are  cellular at the upper part, but in  most, as
 the snake, become smooth bags  at the  lower end,  as it  were,
 answering the same purpose  as  the abdominal bags in the fowl.
 The cells of the  lung-part are large.
   "No proper Diaphragm in either; but  fowls have something
     similar to one.f
   " The Gall is green in  both.
   " The Kidneys are placed in what may be called the pelvis ; in
      both are conglomerated  in  a particular manner ; have  the
      ureter ramifying through their whole substance, and entering
      into the rectum.  The urine is a chalky substance in many of
      both, and a kind of slime in others.
   " The Testes are situated in the abdomen in the male of both.
   " The Vasa deferentia enter the rectum in both.
   " The Penis is grooved in both.
   " Both oviparous.
   " Structure ot Ear  similar in both.
   " Heart very different.  "

   These writings fully attest the enlarged views which Hunter  en-
 tertained of comparative  anatomy,  and of its application not only
to  the establishment of sound theories of the functions  and relative
infiuences of the  diffeernt organic systems in the animal  body,  but
also  of a natural distribution of different animals  into classes  ar-
ranged  according to  their affinities.  It is in this  respect that he
has more especially surpassed  those of his countrymen who have
immediately succeeded him in the same field of inquiry, and  whose

  * See Plates 5, 6, and 7, vol. i. Physiological Catalogue.    f See p. 196. 
PREFACE.
35
labours in comparative anatomy have not been productive of ade-
quate results, chiefly from being restricted to the narrower channel
of their physiological application.
  The museum of Hunter is the chief, but not the sole depository
of the dissections by which he established the general principles to
which we  have alluded.
  Hunter had passed his thirtieth  year before he had collected a
single  preparation for himself.  All that he had made before that
time were  added to his brother's collection, which is now the orna-
ment of the University of Glasgow.  In commencing his indepen-
dent labours, in  anatomy, he conceived the  idea of a collection,
in which the illustrations of the human  organization should form a
part only of a general display of all the types and modifications of
animal structure, and practically he was the  first who reduced the
scattered facts of comparative anatomy to a connected system.
   When Hunter  had brought his museum to an approximate degree
of perfection,* he then set apart certain  days,  in which he exhibited
and explained to  some chosen minds which  could respond to the
conceptions of his own,  his great scheme, embracing  the demon-
stration of all the leading modifications of every organ of the ani-
mal body,  and of the different stages which each organ undergoes
in its development, to fulfil the functions it is required to perform in
the highest organisms.
   Amongst the enlightened men who enjoyed the inestimable advan-
tage of listening to the explanations which the founder of the collec-
tion gave of his own labours, and of their scope and tendency, were
Camper, Poli, Scarpa, and the now venerable Blumenbach.
   Camper, as a  contemporary, and in  some respects a rival of
Hunter, may have been  less  influenced in the  general  tenor and
success of his investigations in comparative anatomy,  by this cir-
cumstance, than the last named and younger naturalists and physiolo-
gists.
   We cannot but suppose that the spectacle of the organization of
so many rare marine  animals, beautifully displayed by so consummate
a practical anatomist as Hunter, must have had a lasting influence on
the mind of Poli;  and it is not, perhaps, assuming too much to trace to
this source the taste for anatomy and the stimulus to the indefatiga-
ble and minute dissections, of the Mediterranean mollusca, and the
magnificent illustrations  of their organization, which have justly im-
mortalized their author.
   In contemplating  the  gradational  and connected series ot the
organs of animals, which Blumenbach must have witnessed for  the
first time in the museum of Hunter, that learned and  accomplished
physiologist was doubtless led vividly to appreciate the cumulative
force with which comparative anatomy urges the onward progress
of physiological science when all its  scattered facts  are concen-

   * In the year 1787.   See Home's Lectures on Comparative Anatomy, vol. i.
p. 7. and vol. i. p. 78 of the present edition of Hunter's Works. 
36
HUNTER ON THE ANIMAL CECONOMY.
trated  into one orderly system.  In his subsequent publications of
the first systematic treatise of comparative  anatomy the erudition
of Blumenbach supplied many of those links in the series of animal
structures which Hunter derived from Nature's original sources.
  In estimating, therefore, the share which Hunter had in advancing
comparative anatomy and  physiology, his annual demonstrations of
his collection to such individuals as we have instanced must not be
overlooked.   We may admit that while so vast a proportion of the
stores of his experience lay buried in unpublished manuscripts, his
strue station in the temple  of  Science could hardly be  discerned;
but, independently of these  manuscripts, we cannot hesitate in allow-
ing that his published works, full of profound and original views, com-
bined with the spectacle of his wonderful  dissections,  must have
effected more than had  been done by any previous author towards
raising the science of comparative anatomy in the scale of human
knowledge.
  Now, however, we  have to estimate the scientific character of
Hunter from more extended grounds.
  Enjoying the same privilege of consulting'his museum, which the
contemporaries of Hunter so highly esteemed, we also  possess the
advantage of studying it with the aid of those explanations of its
scope and nature  which its great founder had left with  a  view to
ulterior publication.
  Thanks to  the devotion of the last of Hunter's  pupils to  the
memory of his great master, the evidences of Hunter's discoveries
and labours, as recorded in his collections, are in a  better state of
preservation at this moment than they were nearly fifty years ago,
when they first fell  to the care and charge of Mr. Clift.   And here
I embrace with pleasure the opportunity of expressing my  grateful
thanks to  that gentleman for  the kind aid which I have on every
needful occasion  received from him during the impression of the
present work, and of  recording my deep sense of the advantages
which  I have derived  from a long intercourse with one whom  I
ever shall regard  as the best of friends and worthiest of men.
   It is to the zeal  and  industry which induced Mr. Clift  to tran-
scribe portions of the  Hunterian manuscripts, at a period when he
little suspected their  ultimate fate, that we owe  our  additional
knowledge of the philosophical views which Hunter entertained of
the application of anatomical  facts, and of the general principles
which  he had deduced from them.  As such of these extracts from
the Hunterian Manuscripts as have been quoted in  the present work
have already been printed  in the Catalogues of the Hunterian  Col-
lections published  under the auspices of  the Council of the Royal
College of Surgeons, it  is competent for  any one to judge of the
grounds on which I have  endeavoured to show that  Hunter, as a
comparative  anatomist, merits a higher, and altogether different
station in  science  than has been awarded to him by Cuvier.
   Instead of viewing Hunter  as one who had merely contributed a
secondary proportion of detached facts to the general but unarranged 
PREFACE.
37
stock of materials in comparative anatomy, it  appears  to me that
he marks a new epoch in  its history, and that  the historian of the
natural sciences has just and sufficient grounds for regarding Hunter
as the first of the moderns who treated of the organs of the animal
body under their  most general relations, and who pointed out the
anatomical conditions which were characteristic of great groups or
classes of animals : as one, in short, throughout whose works we
meet with general propositions in comparative anatomy, the like of
which exist not in the writings of any of his contemporaries or pre-
decessors, save in those of Aristotle.
                                        RICHARD  OWEN.
   November  \5th,  1837.

  N.B. The Editor's Notes  are distinguished from  the Author's by being
placed within brackets. 
 
CONTENTS.
                                                             Page
Preface of the Editor        ........7
 1. Description of the Situation of the Testis  in the foetus, with its
      descent into the Scrotum......41
 2. Observations on the Glands situated between  the  Rectum  and
      Bladder, called Vesiculae Seminales     ....      58
 3. Account of the Free-martin......      70
 4. Account  of an extraordinary Pheasant    ....      79
 5. Experiments to determine the  effect of extirpating  one  ovarium
      upon the number of Young produced         .    .     .    .85
 6. Case of a young Woman who  poisoned herself in the first  month
      of Pregnancy, with a description of the Uterus    .     .      89
 7. On the Structure of the Placenta.....93
 8. Observations on the Placenta of the Monkey       .     .     103
 9. Account  of a Woman who had the Small-pox during Pregnancy,
      and who seemed to have communicated the same Disease to the
      Fcetus.........105
10. Some Observations on Digestion   \.     .     .    .     •     112
11. On the Digestion of the Stomach  after Death       .     .     144
12. On a Secretion in the Crop of breeding Pigeons, for the nourish-
      ment of their Young        ......     149
13. Observations on the Gillaroo Trout, commonly called in Ireland
      the Gizzard Trout.......     151
14. Experiments and Observations on Animals with respect to  the
      power of producing Heat    ...     ...     155
15. Experiments and Observations on Vegetables with respect  to the
      power of producing Heat    ....••     177
16. Proposals for the Recovery of Persons apparently drowned     185
17. Account  of certain Receptacles of Air in Birds, which communi-
      cate with the Lungs and Eustachian Tube    .     .     •     194
18. Description  of the Nerves which  supply the Organ  of Smelling 204
19. Description  of some Branches of  the Fifth Pair of Nerves       209
                                                              211
                                                              238
                                                              254
                                                              262
                                                              265
                                                              277
20.	Croonian	Lectt	ire on Mu
21	Do.	Do.	Do
22.	Do.	Do.	Do
23.	Do.	Do.	Do
24.	Do.	Do.	Do
25.	Do.	Do.	Do
Do.	No.	II.
Do.	No.	III.
Do.	No.	IV.
Do.	No.	V.
Do.	No.	VI.
 
40            HUNTER ON THE  ANIMAL CECONOMY.

                                                            Page.
26. On the Use of the Oblique Muscles      ....     282
27. On the Colour  of the Pigmentum of the Eye  in  different
      Animals     .........     285
28. On the Crystalline Lens, or some Facts relative  to  the late  Mr.
      John Hunter's Preparation for the Croonian Lecture    .     292
29. Account of the Organ of Hearing in Fishes    .     .          297
30. Experiments on Absorption by Veins    ....     303
31. Experiments and Observations on the Growth of Bones   .     319
32.  Observations tending to show that the Wolf,  Jackal and Dog are
      all of the same species     ......      323
33.  Observations on the Structure and CEconomy of Whales   .      334
34. Notes on the Anatomy of the Jerboa    ....      391
35.  Anatomical Description of the Amphibious Bipes of Ellis (Siren
      lacertani,  Linn.)      .......      392
36.  On the Electric Property of the Torpedo     .     .     .      396
37.  Anatomical Observations on the Torpedo    .     .     .      404
38.  Account of the Gymnotus electricus     ....      408
39.  Observations on Bees       ......      415
40.  Anatomical Remarks on  a New Marine Animal (Serpula  gigan-
      tea, Pallas)........456
41.  Observations on the Fossil Bones presented to the Royal Society
      by His Most Serene Highness the Margrave of Anspach      459
42.  Descriptions of some Animals from New South Wales    .      468
       Of the Kangaroo (macropus major,  Shaw)      .     .      472
      Of the Potoroo (Hypsiprymnus murinus,  llliger)     .      474
       Of the Hopoona Roo  (Petaurus Taguanoides, Desmarest    475
      Of the Wha Tapoua Roo (Phalangista Vulpina, Geoffroy)  476
      Of the Tapao Tafa (Phascogale penicillata, Temminck) .    477
      Of the Dingo (Canis Auslralasise)     .         .     .    479