SMALL BOOKS ON GREAT SUBJECTS.
EDITED BY A
FEW WELL-WISHERS TO KNOWLEDGE.
No. II. 
 
THE CONNECTION
PHYSIOLOGY
INTELLECTUAL  PHILOSOPHY.
SECOND EDITION ENLARGED.
    PHILADELPHIA:
LEA AND  BLANCHARD.
        1846. 
6752,
 184k
  PHILADELPHIA:
T. K. AND P. G. COLLINS,
   PRINTERS. 
ADVERTISEMENT  TO THE FIRST
              EDITION.
   In complying with the wish of those friends who
requested me to offer this Lecture to the  Public, I
am extremely anxious to serve what I believe and
hope to be an  increasing class of my countrymen.
It is my strong desire to benefit those who, though
eager for  information, cannot  afford  much time  or
much money for the prosecution  of philosophical
inquiries.   It is then to  the intelligent artizan, who
prefers the Mechanics' Institution to the poisonous
atmosphere  and contaminating society of the gin-
shop: it is  to  the  agriculturist and  the tradesman
who have discovered that an  evening spent in the
smoking-club is not productive of enjoyment  equal
to that derived  from the perusal of such books  as
awaken a spirit of research in their children,  that I
dedicate this volume.
   In revising it, I have been aided by the  works  of
many eminent  physiologists, and by the  advice  of
many kind   cotemporaries.   Among  the  latter,  I
may reckon the Author of " Philosophical  Theories
and Philosophical  Experience" to  whose work,
through the medium of a friend, I had access  while 
vi
ADVERTISEMENT.
it was  yet in manuscript, and whose object it has
been, in common with some  other of his intimates,
to  bring  philosophy into a form that might benefit
the mass of mankind, instead  of being the mere lux-
ury of a few learned men.
  But  to name  the authors  I have  consulted, and
the persons  to  whom I owe obligations, would be
mere ostentation.  It  is  enough to say that I have
not knowingly  neglected  any source of accessible
information.  While I have  striven to  make  these
pages  familiar and intelligible to  all, I  have never
been led to adduce a doubtful  in preference  to a
sounder theory, by the greater ease  with which the
more questionable doctrine might be  expressed.  At
the same time I  have  avoided entering on  any con-
troverted  subject;  and  therefore  I have neither
engaged  with the  interesting speculations of  the
phrenologists, nor with the excito-motory system of
Dr. Marshall Hall, powerfully and attractively as it
has  been advocated  by that philosopher, by Mr.
Grainger, and other eminent physiologists.
                                    J. Barlow.
  London, January, 1842. 
ADVERTISEMENT TO THE  SECOND
                EDITION.
   The little work of which a second edition is now
presented to the public, originally formed one of the
Friday Evening communications to the members of
the Royal Institution  of Great  Britain.   The short
space of time allotted to these communications,—one
hour,—necessarily limited the speaker in the treatment
of his subject to the narrowest possible bounds, and
the Editors conceive that the favor with which it has
already been received will not be lessened by some
addition to its contents, which  will enable them to
give a somewhat more  expanded view of this  most
interesting part of physiology, as well as to notice
any farther  discoveries which may tend to throw
light upon it.
   The Editors of the "Small Books" have  already
had occasion to notice  the almost unexpected  suc-
cess which has attended their undertaking: of course
this excites  a corresponding zeal to deserve it, and
they flatter themselves that the increased quantity of
letter-press in the later numbers of series will be such
as to meet the wishes of those who before  considered
the price too high for  the size of the books. 
 
CONNECTION  BETWEEN  PHYSIOLOGY
                 AND


INTELLECTUAL  PHILOSOPHY.
                      I.

  1. There is  probably no man, who ever thinks
at  all, who  does  not  sometimes ask himself how
that thought is accomplished; how he is so linked
to, yet separate from, the exterior world; and how
and why he is different from the tribes of  sentient
beings which surround him.  He has seen  the pro-
gress  of human nature almost unlimited; yet a dis-
ease, the work of a moment, leaves this half godlike
creature a  helpless  and unreasoning animal.  He
shrinks  with a kind of instinctive horror  from a
state which would yet be the natural and happy one
of many of those classes of sentient beings, and anx-
iously asks himself," What then is  his destination?
What the ultimate object of his existence?" These
are a few of those riddles of life, which, however
little they may  form the  topics of  general  conver-
sation, lie uneasily  in the secret recesses  of most
men's minds; and if in our subject of this  evening
I can solve some of them, my hearers will probably
not think their attention ill bestowed. 
  10      CONNECTION BETWEEN PHYSIOLOGY

    2. The earth, the water, and the  air, are thickly
  peopled with various forms of living creatures: it is
  therefore desirable  no less for the  common inter-
  course of life than for  scientific purposes, that these
  animated beings should be grouped together on some
  principle of mutual resemblance; accordingly, sys-
  tems of classification have been in use from the very
  earliest periods.  I do not now purpose to enter into
  the history or the comparative merits of these modes
  of classification;  it is sufficient to  select the one
  which I believe to be  most philosophical, which I
  know to be best adapted to make my views intel-
  ligible, and which originates from the most eminent
  physiologists of our time.  It is based on the differ-
  ence of the nervous  system in the respective classes,
 which is more and  more developed  in each, till it
 arrives at its final perfection in man.
 a.  Crypto-neura, the hidden-nerved.—Rudolphi.*
   This  includes coral insects, madrepores, sea-ane-
     mones, sea-nettles, hydatids, flukes, some abdomi-
     nal worms, &c.
       In these animals,t "  The neurine or nervous
     matter, if existing at all, being incorporated with
     the other  tissues, cannot be  demonstrated as
     forming a separate system."
b. Nemato-neura, the thread-nerved.—Owen.
   This includes many of the infusorial and micro-
     scopic animalcules, and (what  the ordinary ob-
     server is more  familiar with) star-fishes, sea-
     urchins, &c.
       In these  animals  there  is  usually  found a
     thread-like  ring round the gullet, from whence

  * Beytrage sur Anthropologic, quoted by Jones, General Out-
line of Animal Kingdom, p. 6.
  t Solly on the Human Brain, p. 5. 
          AND INTELLECTUAL PHILOSOPHY.       11

    minute filaments occasionally proceed to  other
    parts of the body.
c.  Homogangliata, animals whose ganglia are sym-
    metrically arranged.—Owen.
   This division comprehends  (together with  less
    known animals) leeches, earth-worms, scolopen-
    dras, insects, scorpions, spiders, lobsters, crabs,
    &c.   This division is characterized by having
    the  nervous masses (ganglia)  distributed over
    the body at regular intervals, corresponding to
    its well-defined segments.
d. Heterogangliata, animals in which the arrange-
    ment of the ganglia is not symmetrical.—Owen.
   In this  division are found barnacles, oysters, mus-
    cles, snails, cuttle-fish, &c.
       In this large group of animals, that symmetri-
    cal arrangement of parts so conspicuous in the
    ray of the  star-fish, the segment of the  insect,
    &c,  is  no longer  observable;  and the nervous
    system  is as irregular in its distribution  as  the
    organs which it supplies are disproportionate to
    each other in their size.
e. Myelencephalia, animals  possessing a brain in a
    bony skull.—Owen.
   This group  requires no  additional description at
    present; it comprehends fishes, frogs, reptiles,
    birds,  mammalia,  and  at  the  head of these,
    Man.
   3. It will  be  observed in the foregoing table that
a nervous system has been traced in all animals (that
is, in all beings that  can feel and move), except in
those  comprehended in  the  division a.  But it is
extremely probable that this system also exists ia
the cryptoneura, although its presence has not yet
been detected in them,* since they exhibit sensation
* Carpenter's Inaugural Dissertation, p. 76. 
12      CONNECTION BETWEEN PHYSIOLOGY
and  voluntary powers.   The nervous system con-
sists,
   1.  Of  nerves and  irregularly shaped masses of
     nervous matter, called ganglia.
   2.  Of  a prolonged  cord of nervous  matter both
     vesicular and fibrous,  sheathed  in its  proper
     membranes;—or as some  think, of a series of
     connected ganglia;—the whole protected by the
     vertebrae  of the  spine, which  are hollowed to
     receive it.
   3.  Of a superadded brain, or, as some have con-
     sidered it, a collection of ganglia connected with
     the organs of sense.  This brain is always de-
     fended  by a bony case, or  skull.   It  is  found
     only in the  animals  of division e.
   4.  The nervous  matter which forms this compli-
cated system is varied  both in appearance, and most
probably in function.   It may be classed under two
divisions, the vesicular and the fibrous.  " The vesi-
cular nervous  matter is  gray or  cineritious  in  color,
and granular in texture:  it contains nucleated  nerve
vesicles,* and is  largely  supplied with blood.   It is
more immediately associated with the mind, and is
the seat in which originates  the  force  manifested in
the nervous system.  The fibrous nervous matter, on
  * " The essential elements of the gray nervous matter are
vesicles,  or cells containing nuclei and nucleoli.  They  have
been called nerve or ganglion globules.  The wall of each  vesi-
cle consists of an exceedingly delicate membrane, containing a
soft but tenacious, finely granular mass.  The nucleus of the cell
is generally eccentric, much smaller than the containing vesicle,
and adherent to some part of its interior.  Its structure is appa-
rently the same as that of the outer vesicle.  The nucleolus ia
a minute, remarkably clear, and brilliant body, also vesicular,
enclosed within the nucleus.  It forms a most characteristic and
often conspicuous part of the nerve-vesicle."  Todd and Bow-
man's Physiology, vol. i. p. 212. 
AND INTELLECTUAL PHILOSOPHY.
 the other hand, is, in most situations, white, and com-
 posed of tubular fibres, though in some  parts it  is
 gray, and consists of solid fibres.  It is less vascular
 than the other, and is simply the  propagator of im-
 pressions made upon it.  When these two kinds  of
 nervous matter are united together in a mass of vari-
 able shape or  size, the body so formed  is called a
 nervous  centre,  and  the  threads  of fibrous matter
 which  pass to or from it are called nerves.  The
 latter are internuncial in their office: they establish
 a communication between the nervous centres and
 the various parts of the body, and vice versa.  The
 smaller nervous  centres are called  ganglions: the
 larger ones, the brain and spinal cord."*
   5.  When  examined by the  naked eye and the
 finger, a nerve is a soft, white, thread-like substance.
 In  its  course  it resembles  a leafless  branch.   It
 spreads  out  into small nervelets  or filaments, and
 thus diminishes or increases in size according as it
 is traced from  or towards the central cord or ring  in
 which it originates.   But when carefully  viewed by
 the microscope,! each nerve is found to  be a  mere
 bundle of extremely small tubular  filaments, contain-
 ing a sort of half fluid pith.   These are  separately
 enclosed and connected together by a covering of a
 very  delicate  texture, and  the  whole is cased in a
 thin membranous sheath.  These fibrils  sometimes
 unite with, sometimes  cross  over  each other, some-
 times form new groups with detachments from other
 bundles, sometimes are twisted over each  other: but
in no  instance  does the minutest,fibril so penetrate
another that there can be a mixture of their compo-
nent particles.   Therefore, although the number of
* Todd and Bowman's Physiology, vol. i. p. 205.
t Carpenter's Principles of Physiology, p. 42. 
14      CONNECTION BETWEEN PHYSIOLOGY

nervous filaments is  immense, there can be no con-
fusion  in  the discharge  of their functions.   "The
nerves appear to be formed after the same manner
as the muscles, i.  e., by the  fusion of  a  number of
primary  cells arranged  in rows into  a  secondary
cell.  The primary  nervous  cell, however, has not
yet been  seen  with perfect  precision  by reason of
the difficulty of distinguishing nervous cells, while
yet in their  primary state, from the indifferent cells,
out of which entire organs are evolved.  When first
a nerve  can be distinguished as such, it presents
itself as a pale  cord with a longitudinal fibrillation,
and in this cord a  multitude of nuclei are apparent."
"According to Valentin's description, the following
is the process of development of the nerve vesicles.
In  the very young  embryos of mammalia, as the
sheep or calf, the cerebral mass in the course of for-
mation contains in the midst of a  transparent blas-
tema, transparent cells of great delicacy with a red-
dish-yellow nucleus.  Around these primitive cells,
which we find likewise formed after the  same type
in the spinal cord, a finely granular  mass becomes
deposited, which probably is  at first surrounded by
an enveloping cell membrane.   At this early period
of formation the primitive cell still preserves its first
delicacy to  such a degree that  the  action of water
causes it  to burst immediately."*
   6. The functions  of the nerves are various: expe-
rience has shown that the intervention of nerves is
absolutely necessary;  1, to the continuance of ani-
mal life;  2,  to the reception of sensation; and 3, to
the production of movements in all the higher orders
of animals;  and from analogy it has been conceived
that  even if it have hitherto  eluded observation,

      * Todd and Bowman's Phys., yol. i. pp. 227, 228. 
          AND INTELLECTUAL PHILOSOPHY.        15

nervous matter does exist, even in the lower tribes;
for organic life is  possessed no  less  by the rooted
zoophyte, which seems  scarcely to have any con-
sciousness  of the  exterior  world, than  by man.
But the  actions  of man  being  all destined to  be
modified by his rational faculties, a more complex
arrangement  is  requisite  in his  case,  in order to
bring the whole system into harmony.   The func-
tions of animal  life, therefore, are carried on by a
machinery which, though capable of acting alone, is
yet so connected with the organs of the higher facul-
ties, as to be placed in great measure  under  subjec-
tion to them.
   7.  At the head  of  this machinery stands that  set
of ganglia, and their  connecting nerves, which is
known to anatomists as the sympathetic, ganglionic,
or tri-splanchnic*  system, or sometimes, in older
writers,  as the  great intercostal nerve.    This is
found extending from the base of the skull in a dou-
ble chain of ganglia  on  each side of  the vertebral
column, interiorly  as regards the  body, and passing
within the ribs towards the lower part of  the trunk.
Throughout its  course, numerous nerve  fibres  are
thrown out to supply the viscera both of the thorax
and  abdomen, and  "branches  attach  themselves to
the exterior of arteries, forming very intricate plex-
uses, which entwine  around them,  hederae  ad mo-
  * So called from g-ir'Ka.yxya., viscera : " We may with de Blain-
ville consider it as divisible into two parts, one placed in front
of the spine (prevertebral) composed of plexus and ganglia (se-
milunar and cardiac), whose branches are  distributed to the
primary organs of digestion and circulation : the other consisting
of two knotted cords, extended along the whole length of the
spine, communicating with the prevertebral plexus on the one
hand, and with the cerebro-spinal nerves on the other."—Quain
and Wilson's Anatomy of the Nerves, p. 4. 
16      CONNECTION BETWEEN PHYSIOLOGY

dum" (Scarpa).   The  ganglionic system is closely
connected with both the brain and spinal cord at its
offset, and keeps up a communication with this last,
through the whole of its course, by means of a white
and a gray filament, which both  pass between each
ganglion and the anterior root of each spinal nerve.
Thus the  series of  nerves  and ganglia  which send
out branches to every part connected with respira-
tion, nutrition, and  circulation, are united by inter--
change of fibres with the spinal cord, and are thus
connected with the  brain.
  8. The sympathetic system  may be considered
as the chief agent in the maintenance of animal life:
for the  maintenance of life  depends on  nutrition,
and nutrition consists in the constant assimilation of
fresh substance to supply the place of what is thrown
off in the  continual state of movement  and change
which constitutes what we  term good health.   The
analysis of animal bodies  gives about four element-
ary substances (hydrogen, oxygen, carbon, and nitro-
gen), which are found  in  like manner to compose
the air that we breathe and the  food that we eat:
but no human  art  has succeeded in compounding
from them the smallest particle of organized matter,
and we remain in great measure ignorant of the ex-
act nature of the  changes which convert food and
air into  the  texture of  the  body.  All that we can
know, therefore, is, that the sympathetic system is
the immediate instrument of effecting these changes,
and that by  some yet undiscovered properties of its
nerves and  ganglia, inanimate matter  is made to
share the life of the part  to which it is  assimilated.
It is remarkable that, unlike all other nerves, those
connected with the system we  are  describing, are
neither susceptible of sensation so long as they con-
tinue in a  healthy state, nor do they require an effort 
          AND INTELLECTUAL PHILOSOPHY.        17

 of  the mind to  keep them  in  action.   The organs
 supplied by the sympathetic nerves are equally un-
 like the other  members of the  body in properties
 and in structure.  For  the limbs  are  disabled for
 a time  by  fatigue  after long-continued  exertion,
 whereas the heart, lungs, &c, whose vital action  is
 sustained by this system, never require rest, although
 always in exercise.  As it is essential  to our exist-
 ence that the operation of these organs should be
 unintermitting, it is most fortunate for  us  that they
 so  rarely excite our notice;  for we should never
 enjoy a moment's repose, were it necessary to keep
 up  the circulation, respiration, &c, by a  constant
 attention  to them.   And though  this   system ex-
 acts so little from our  intellectual powers, rejects
 the  control of our will, and  rarely disturbs us by
 exciting a sensation, it  nevertheless does  strongly
 sympathize with  our bodily and  mental feelings.
 The heart, whose unwearied and unfelt movements
 are the result of its influence, throbs uneasily during
 the period of anxious and fearful expectation, and
 so forcible is the impulse given  by powerful  emo-
 tion, as sometimes  to rupture the parts  by a rush  of
 blood.  I have  already  touched  on the connection
 of nerves by which this is effected, and it must be
 noticed again when  I come to  treat of instinctive
 emotions.
  9.  Such then  is the  apparatus of mere  organic
life.   But this  life requires support and defence  in
all but the very lowest division of  the  animal king-
dom.  The crypto-neura  are, indeed,  without ex-
ception, inhabitants of fluids; they therefore depend
for subsistence on the casual nutriment  that may be
floated towards them: their bodies, too, like plants,
may be mutilated to a great extent, and  yet preserve
their vitality, as they are  capable of reproducing  a
     2 
18
CONNECTION BETWEEN PHYSIOLOGY
 severed part: but it is not so with the higher orders
 of animals:  with them  dismemberment is fatal, or at
 best  irreparable.   These also  have  to select or to
 seek their food, and  must be warned against the ap-
 proach of danger: a further apparatus of nerves is
 accordingly provided, by which they can take cogni-
 zance of external objects, and these nerves are usually
 termed the nerves of the  senses.  I shall not stay to
 inquire  in how large a degree the  inferior orders of
 animals possess them;  in the higher they  consist of
 smell, sight,  hearing, taste, touch,  and  perhaps,—for
 on this point physiologists are not wholly satisfied,—
 of general sensation.* For all but the two last named,


   * A curious case recorded  by the late Dr. J. Cheyne seems to
 favor the opinion that there may be a set of fibres conveying to
 the brain a sense of general sensation  independent of the sense
 of touch.  " We know an instance," says he, " of a remarkable
 delusion, arising from complete loss of feeling in the  left side
 of the body, caused by an attack of palsy, which first originated,
 and then  fatally terminated in  apoplexy.  In  the morning  the
individual maintained that he had two left arms, and when  we
tried to convince him that he  was under  a misconception, he
promptly offered to produce the supplementary arm.   ' There it
is,' said he, patting his left shoulder with his right hand.  « Well
then,' it was asked, < where is the other V—On which, turning
round his head with great alacrity to show it, he seemed  much
disappointed when  he could discover but one  arm, vehemently
declaring that' there were two, in the night.' "   Cheyne's Essays
p. 60.  Here there must have been general sensation in the arm!
or  the patient would not have felt that he had an arm at all__but
when in the night he felt but  could not see that he had an arm
and on touching  the surface of the palsied limb with the other
hand, was sensible of no  impression, he naturally supposed  the
real arm to be existing  behind or  beside  the  dead substance
which he touched. Between sleeping and waking even in health we
do not always reason  and here probably the reasoning power was
somewhat disturbed by the lesion of the brain.  If there shnnlH
be a sense of this kind it would account for the fact that vain is
felt in palsied limbs which are insensible to touch; as welf as fo
those cases of insanity or idiocy where the sens* «f Z.  u
mains, but that of heat, or the pa'in cnsuingVoTa* burn,TsVsT 
AND INTELLECTUAL PHILOSOPHY.
if two they be, a system of nerves within the skull,
and in direct commutation with the brain, is pro-
vided; whereas, the senstof touch being distributed
over  the whole body, is  co,veyed  to the  common
centre of sensation by an immeue number of nervous
filaments, which either plunge iHo the   inal  cQrd
through small openings in the bone PVided for them
and thus find their way to the brain,  o^„re immpcij'
ately  connected with  it.                 -v
  10. Thus far I have  described the macrrK,    *
life and  sensation only, but it is further nece%.
that the living sentient animal should  have the mea^.
of preserving his existence, of seeking pleasure, and
of avoiding pain.   This is accordingly provided for
by  another set of nerves, the nerves of voluntary
motion.   The operation of these nerves however is,
in respect of direction,  opposite to that of the nerves
of sensation.   It is by means of the latter that con-
stant  communications from all parts  of the body to
the brain are carried  on.   The nerves of motion on
the contrary issue from the brain, and convey its
mandates to whatever part it would  control.  This
constant interchange  somewhat  resembles what  is
carried on  between the  provinces and the capital by
the mail-trains.  The  nerve of  sensation, like the
train  which conveys  letters to the capital, receives
continual contributions from the tracts which it passes
through, until the whole, compressed into the small-
est compass, is delivered at the  central post-office:
and in like manner the  nerve of motion, like the out-
train, keeps sending  forth its district mails  at each
successive station, until the most distant one is de-
livered at the terminus.
   11. Thus we have three distinct systems of nerv-
ous mechanism in the  living body, each dependent
on the other, namely, 
 20      CONNECTION BETWEEN PHY^OLOGY

   ,  The unconscious invoking nerves of life;
   [I. The conductors of ex-^nal and internal feel-

   ra!D?h?conve^^'^2|JjiOnA«"1 the brain t0

 whic^are^respe avely termed the sympathetic, the
 sensitive an^ 5ie motor  nerves-
   12  I ,yve  &lready described  the Sympathetic
 „   '   /) as a series of  ganglia with  connecting
  ^  ,o, whose office it is to supply the nervous energy
 i. which the functions of circulation, secretion, &c,
 are unconsciously carried on.  The composition of
 these nerves differs  considerably from  that  of the
 spino-cerebral system, being formed chiefly of a gray
 gelatinous fibre, not  found in any great abundance
 elsewhere.  These fibres seem to form an interme-
 diate substance between  the vesicular,  and  fibrous
 nervous  matter; (4.) for  they contain among them
 " numerous  cell nuclei, some situated in the centre
 of the fibre, others adhering to either  edge, and fre-
 quently exhibiting distinct  nucleoli."—"The mode
 of connection of the gelatinous fibres with the ele-
 ments of the nervous centres," say the authors of the
 work from which I have  already quoted, " is, as yet,
 quite  unknown.  They  are found  in considerable
 numbers in what are called the roots of the Sympa-
 thetic, or the communications of that nerve with the
 spinal nerves ; and it has  been supposed by Valentin
that they are continuous with certain elements of the
vesicular nervous matter."1—That vital power by
 which the common functions of nutrition and repro-
 duction are carried on, has been termed by Professor
Liebig,—"vegetative life," and  in the acknowledged
obscurity which hangs over the modus operandi  of
* Todd and Bowman's Phys., vol. i. p. 212. 
          AND INTELLECTUAL PHILOSOPHY.        21

the nervous  power, it may be allowed to throw out
as a hint for future consideration, that the cell nuclei
so largely interspersed  among  the gray gelatinous
fibres  of the sympathetic ganglia  and nerves, have
no  small analogy with  the primitive forms of the
vegetable world.   In both  kinds of organic life, the
cell seems to be the first and simplest form assumed
by incipient organization ;* in both the granules con-
tained within  the cells  have been seen in motion,!
although no shock has been communicated to them
externally.   Whence  this motion  arises is not easy
to decide, but movement being produced,  the  first
condition of assimilation,  and  consequently of the
maintenance of life,  is there.   And here a wide field
opens itself:—electricity has been considered, nay,
may  we not say, proved,  by Prof.  Faraday to be
merely  a phenomenon  of matter, the consequence
of molecular movement communicated by chemical
change; and Prof. Matteucci of Pisa has proved by
a series  of experiments that animal muscle is capable
of taking the  place of metals in forming a  galvanic
  * See Carpenter's Physiology, p. 15.
  t " Such motions are either of a uniform and rhythmical kind,
or they are apparently irregular and oscillating.  Those of the
former kind are familiarly known in the vegetable kingdom by
the Cvclosis which takes place in the oblong cells of Chara. The
granules which may be seen in motion are quite passive, and are
carried along by currents within the cell.  Motions of the latter
kind  have been seen by Schwann among the granules contained
in the cells of the germinal membrane of the  hen's egg, as if
occasioned by an endosmotic current through the wall of the
cell.   This membrane is the seat of active change, the deve-
lopment and growth  of new cells destined for  the evolution of
the textures of the embryo.  A molecular motion of the same
kind  may be seen in the very minute granules which occupy the
cells of the membrane of black pigment on the choroid coat of
the eye.  Whether this goes on during life is of course impossi-
ble to say, but the conditions for its production are undoubtedly
present."  Todd and Bowman's Phys., vol. i. p. 59. 
22
CONNECTION BETWEEN PHYSIOLOGY
current:* and heat is generated where electrical action
is excited.   No series of experiments has yet proved
that  these isolated facts  of science  have  any inti-
mate relation to each  other,  but an  inquiring mind
cannot avoid  asking the question, have they not?—
Is not the movement which is excited within the
primitive cell,—though perhaps merely the result of
endosmose,—the first step in a series of phenomena,
each resulting from the other till the most  complex
machinery of organic  life is  developed and kept in
action.!  Whether the nucleated cells found so plenti-
fully scattered among  the gray fibres of the sympa-
thetic  system  may generate  and  propagate  such
movement, of course is not, perhaps never may be,
ascertained; but if it were so, it would be one more
instance to add to the many that modern science has


  * "The  organic actions  of  muscle by which  the electrical
current is developed may be compared to the inorganic pheno-
mena attending its production from the decomposition of metals.
When a plate of metal, immersed in an acidulated fluid, is oxi-
dized by the oxygen of the water, and then dissolved in the acid,
we admit that an enormous quantity of electricity is developed
during this action.—The  metal acted upon in the artificial ar-
rangement is represented, in  the phenomenon of the muscular
current, by the muscular fibre; the acidulated fluid is the arterial
blood.  The surface of the  muscle,  or any other conducting
body, not muscular fibre, but which is in contact with the mus°
cle, represents the second plate of metal, which does not suffer
chemical action, and which serves only to form the circuit.  The
direction of the muscular current is precisely such as it should
be supposing the current to  be as we have represented it, due to
chemical action  taking place in the interior of the muscle."
(The  direction of the current is from the interior to the exterior )
The  above is quoted from  Matteucci's communication to the
writers of the work on Physiology already quoted, vol. i p 383
and there the experiments are detailed by which Prof. Matteucci
proved the facts above stated.
  t Both electricity and heat are present in the germination of
seeds;—are not both, poss.bly, modifications of molecular move-
ment? 
          AND INTELLECTUAL PHILOSOPHY.       23

discovered, of the beautiful simplicity of means by
which the mightiest  effects are  produced,  where
Perfect  Knowledge  and Perfect Power have
been employed in conjunction.
   13.  We have now  to consider another system of
nerves differing  both  in  function and  appearance
from  the  foregoing: i. e., the spinal.  These issue
from each side of the spinal cord, to the number of
thirty-one pairs, but each individual nerve is attached
to the cord by two sets of filaments (15) which from
their  respective situations are termed the anterior
and posterior roots of the spinal nerves.*  The pos-
terior root is distinguished by a ganglion found on it
near its point of junction with the cord; the anterior
passes over this ganglion, but sends no fibres  into it,
although both at their exit from the vertebral column
are wrapped in  the same  common  covering:  but
presently after, the fibres  of each root cross over
each  other, and the two great branches into  which
this compound nerve soon divides, contain bundles
of fibres  connected with both roots.   It had long
been observed that, in  cases of palsy, sometimes the
power of voluntary movement, sometimes the sense
of touch was destroyed, and this, upon  examination
after  death, was  found to have been  caused by  a
lesion of  some part of the brain;  at other times the
same effect was  produced by injury or disease of
different parts of the spinal cord.  About the begin-
ning of this century this circumstance began  to give
rise to speculations on the possibility that the separate
roots of the nerves might have  separate functions,
and that the fibres of each root which, though cross-
ing and intermingling in their common  sheath, are
yet kept perfectly separate by the fine membrane or
* See Quain and Wilson's Anatomy of the Nerves, p. 35. 
24      CONNECTION BETWEEN PHYSIOLOGY
  nerve lemma that invests them,—might be the means
  of carrying to the brain the sensations received at the
  extremities, on the one hand, and conveying back its
  mandates  on the other:—in  short, that  these roots
  were respectively sensitive and motor, consisting of
  fibres communicating with certain tracts of the spinal
  cord, which  in their turn  communicated  with  the
  brain, and thus that injury of any part of the sensi-
  tive  tract would destroy sensation;—or in like man-
  ner  impede  the propagation  of movement to  the
  limbs, if the  injury happened to occur in  its  path.
  Curiosity being  thus awakened, numerous experi-
 ments were made, in order to ascertain the fact: and
 living animals were mutilated and  tortured without
 mercy for the purpose of determining which  function
 belonged  to  which  root.  It  is extraordinary that
 even if humanity did not prevent this, common sense
 at least should not have interfered so far as to suggest
 that when the processes of the spine have been hack-
 ed open,—when pain and loss of blood have disor-
 dered  all the  functions of  nature,—and when,__
 happily for the poor animal,—death is  imminent,'-—
 no rational conclusion can be formed as to the normal
 functions of the parts.*  The controversy was long

  * "Direct experiments on the anterior and posterior columns
 of the cord are surrounded with difficulties which embarrass the
 experimenter and weaken  the force of his inferences  The
 extern tSa^iW IhV'T6' r m°St ^^l^LuX


crepancies which are apparent-in iherlZtZ^^ ^ di*
periments which have been publ shed  ™ Tf'XL  t,he.va"ous ex"
of the cord ' observes Dr Nn,t <      "the anterior fasciculi
f slightdegree The?™^iT£e™^%>at <?'*
laymg  bare the cord, must ca'use &* tto^?^^^ 
AND INTELLECTUAL PHILOSOPHY.        25
and hot;  and many opinions were broached as to the
functions of the anterior and posterior roots of the
spinal nerves which  subsequent and calmer investi-
gation has greatly modified.   The  common sense
view too  has gained ground," and it is acknowledged
that a careful register of the phenomena of disease,
followed  by a post-mortem examination, is generally
more to be depended on than the experiments, so re-
volting to humanity, which were at first resorted to;
but from which, nevertheless, different therorists drew
different  results, each in favor of his own especial
view of the case.
   14. Whilst the  controversy was  yet raging with
a  fierceness  hardly  befitting a  scientific question,
Dr. Marshall Hall suddenly stepped in,* and gave
a  new character  to  the inquiry.  He proved  that
there were many  actions which appear to be volun-
tary which nevertheless  take place during a state of
utter  insensibility,! or even, in some animals, as in
weaken or destroy the manifestation,' &c."  Todd and Bowman's
Phys., vol. i. p. 317.
  Alas!  that this should have been only a late thought! too late
to prevent the infliction of tortures which the mind shrinks from
contemplating, and which I will not pain my readers by detail-
ing.
  * I give the name of this gentleman because he was the most
active in drawing attention  to phenomena, which, though they
had been noticed by some others, had not been sufficiently con-
sidered.
  t The cerebral system of nerves conveys  impressions from
every part of the body to the brain, and the individual then feels
them as sensations,  and by the fibres of the same system, which
pass from the brain to the muscles, the will acts upon them in
producing voluntary motion. Now the  brain is not in constant
action, even in a healthy- person ; it requires rest: and during
profound sleep it is in a state of complete torpor.  Yet we still
see those  movements  continuing which are essential to  the
maintenance of life,—the breathing goes on uninterruptedly,—
liquid poured into the mouth is swallowed,—and the position is
3 
26      CONNECTION BETWEEN PHYSIOLOGY
 the  turtle, for instance, after  decapitation: actions
 which  continued to  be performed for some  time
 whilst  the spinal cord remained intact, but  ceased
 instantly on  its removal.   It was farther shown,
 that in the case of a monstrous birth, where the brain
 was wholly wanting, the infant, during some hours
 sucked and performed the other functions of com-
 plete animal  life;  and that  in palsy, limbs  which
 were insensible to  the commands of  the  will, had
 yet  their  own proper  movement.   Hence  it  was
 very rationally inferred, that the  spinal apparatus is
 sufficiently independent of the brain, to be capable
 of action without its aid, and that by its intervention
 many of the  actions requisite to the preservation of
 life can be, and actually, in many instances, are per-
 formed :  thus proving that besides  the unconscious
 vegetative life of the sympathetic system, there is
 an unconscious  animal life, whose centre is to be
found  in the spinal  cord.    For these  functions,
 which he distinguished as reflex, Dr. Marshall  Hall
 supposed a peculiar set of fibres  to be appropriated,
 which  he termed excito-motory.   He considered
 that " the  various muscles and sentient surfaces of
 the  body  are connected  with the brain  by nerve
 fibres  which  pass from one  to  the other.   Those
changed when the body would be injured by remaining in it.
The same is the  case in apoplexy, in which the actions of the
brain are suspended by pressure upon it: and the same will
take Place in an  animal from which the cerebrum is removed
or in which its functions are completely suspended by Severe
b ow on the head.  If the edge of the eyelid be touched with a
straw, the l,d immediately closes : if a candle be brought near
lu^^t^S^^^ P<Td into^rnouS
taper, it is withdrawn, and f S.K exDer'impS'K' "'V "^
frog, the animal will  opawa   »  P,'?   bre madue uPon a
of irritation.  Ca^J^JS^A^S^^S^ """'" 
         AND INTELLECTUAL PHILOSOPHY.       27

fibres destined for, or proceeding from the trunk to
the brain, pass along  the  spinal cord, so  that that
organ  is in great part no more than a bundle of
nerve fibres going to  and  from the brain.   These
fibres  are  especially for sensation and  voluntary
motion.  But in  addition to these, there is another
class of fibres proper  to the spinal cord, and to its
intercranial  continuation which form  a  connection
with the gray matter  of the cord  (15).  Of these
fibres some  are afferent or incident, others efferent
or reflex, and these  two kinds have an immediate
but unknown relation to each  other, so  that each
afferent nerve has its proper efferent one, the former
being  excitor, the latter motor.—These  fibres  are
quite independent of those  of sensation and volition,
and  although bound up with  sensitive  and motor
fibres,  they  are  not  affected  by  them,  and they
maintain their separate course in the nerves as well
as the centres."*  But  this theory, however inge-
nious,  is still but a theory; unsupported  as  yet by
any  anatomical  proof, though the  phenomena  on
which it is founded are established facts: it therefore
awaits the confirmation, which perhaps we are never
destined to attain,  of a more accurate  anatomical
knowledge of parts so  delicate  in their structure,
that  they have hitherto in great measure baffled the
inquirer.  Before going further, however, it may be
well to give what is known respecting the nature of
the organ which  plays  so  important  a part in the
animal economy.
   15.  "The spinal  cord is somewhat cylindrical in
shape, slightly flattened on the anterior and posterior
surfaces,"  and is considerably thickened in those
parts where the nerves  supplying the  limbs  are

        * Todd and Bowman's Phys., vol. i. p. 323. 
28      CONNECTION BETWEEN PHYSIOLOGY
given off or received.   It is divided down the mid-
dle "by an anterior and posterior fissure  into  two
equal and symmetrical  portions, of which one may
be called the  right, the other the left spinal cord.
A transverse bilaminate partition, extending through
the entire length of the cord, separates these fissures
from each other, and serves to unite the lateral por-
tions.  This partition is composed of a vesicular or
gray, and a white or fibrous lamina or commissure,
the gray being situated  posteriorly.—On further ex-
amination of  a transverse section of the cord we
observe that the interior of each half of it is occu-
pied by vesicular matter, disposed in somewhat of a
crescentic form, thus:
The concavity of this crescent is directed outwards,
its anterior extremity or horn  is thick; but the gray
matter is prolonged backwards in the form of a nar-
row horn, which reaches quite to the surface of the
cord.  The prolongation of the posterior horn of
each gray crescent to the  surface, divides each half
of the cord into  two  portions.  All that is anterior
to the posterior horn  is called the antero-lateral co-
lumn, and this comprehends the white matter form-
ing the sides and front of that half of the cord   The
posterior column is  situated  behind the  posterior
horn of gray  matter.  The antero-lateral  columns
are  united across the middle line by the  anterior or
white commissure;—the gray crescent  by the pos- 
AND INTELLECTUAL PHILOSOPHY.        29
tenor  or  gray commissure, while the posterior co-
lumns are not connected, except when the posterior
fissure  is imperfect  or deficient.   The  roots of the
spinal nerves emerge from  the  cord on each side
along  two lines;  the posterior line  corresponds to
the margin of the posterior horn of gray matter; the
anterior one is placed about midway  between it and
the anterior fissure.   The roots of the nerves pene-
trate the  substance of the cord, and are chiefly, if
not  entirely, connected  with the antero-lateral co-
lumn.   So far as our  present  knowledge  of the
minute anatomy of the spinal cord extends, it is
favorable  to the supposition  that  the spinal nerves
derive their  origin,  at  least partly,  from the  gray
matter.   The longitudinal fibres  of  the cord may
consist in part  of fibres continuous  with those of
the brain  or cerebellum,  and  in part, of commissural
fibres, serving to unite various segments of the cord
with each other, or to connect some part or parts of
the encephalon with them.  These fibres which may
be regarded as  strictly spinal, are probably oblique
in their course, forming  their connection with gray
matter at  a point  higher up in the  cord than that
at which they emerge from its surface, and may rea-
dily be confounded with  the longitudinal fibres when
their  course  is  long.  Other oblique or transverse
fibres  probably do not  emerge from the cord, but
connect the segments  of opposite sides, forming a
transverse commissure.   So  that four classes  of
fibres,  each different in function, may be considered
to exist in the  cord.  1. Spinal fibres oblique  or
transverse, which  propagate nervous power  to  or
from the segments of the cord itself.  2. Encepha-
lic fibres; longitudinal;  the paths of volition and
sensation, which connect the spinal  cord with the
various segments of the  encephalon.   3. Longitu- 
30      CONNECTION BETWEEN PHYSIOLOGY

dinal commissural fibres.  4. Transverse commis-
sural fibres.
  16.  Whilst the functions which, till a better term
is  found,  we  must term  reflex (14), were  as  yet
either unknown,  or considered  merely as  isolated
and strange phenomena; the controversy was warm
as to the  respective offices of the posterior and  an-
terior columns of the cord, as well as of the two roots
of the nerves : but nothing would now be gained by
going over ground, much of which  has been aban-
doned, and  I  prefer quoting  the  following very
rational theory, which  will  give  a  notion  of  the
question  as  it  at present stands.  " We are much
disposed to think," say  the authors  of " the Physio-
logical Anatomy of Man," "that the antero-lateral
columns are the centres of the main  actions of the
cord.  Both roots  of the nerves are connected with
these columns, and therefore fibres of sensation and
motion must be found in them.  These columns are
always proportionate to  the nerves which arise from
them;  they enlarge when the nerves  are large, and
contract when  the  nerves diminish in size.  The
posterior columns, on the other hand, are of uniform
dimension throughout nearly the  entire length of the
cord, although  the posterior roots of the nerves ex-
hibit considerable difference  in point  of size in dif-
ferent  regions.  We venture to suggest,  that  the
posterior columns  may have a function  different
from any hitherto assigned to them.    They may be
in part commissural between the different segments
of the cord, and in part subservient to the function
of the cerebellum (17), in regulating and co-ordinating
the  movements necessary for  perfect locomotion.
The analogy of the brain, in which the various seg-
ments  are connected by longitudinal  commissures
suggest the probable existence of fibres  similar in 
AND INTELLECTUAL PHILOSOPHY.        31
office for the spinal cord.  If we admit such  fibres
to be necessary to insure harmony of action between
the several segments  of the encephalon, there are as
good grounds  for supposing their existence in the
cord, which in reality may be regarded as consisting
of a number of ganglia, each a center of innerva-
tion to its proper segment of the body, and therefore
requiring  some special connecting  fibres to secure
consentaneous action with the  rest.   The attribute
of locomotive  power rests upon the connection of
the posterior  columns with  the cerebellum, and the
probable influence of that organ over locomotion. If
the cerebellum be the regulator of locomotive actions,
it seems reasonable to suppose that  those columns
of the cord which mainly pass into it should  enjoy
a  similar function; that, as they are the  principal
medium through which the cerebellum is  brought
into connection with the cord, it must be  through
their constituent fibres  that the  cerebellum exerts its
influence  on  the  nerves  of the lower extremities,
and of other parts concerned in the locomotive func-
tion.—We think that the phenomena of disease may
be  referred to in support of our view.  In  many
cases, where   the  principal symptom  has been a
gradually increasing  difficulty of walking, the pos-
terior columns have been the seat of  disease.   In a
remarkable case  related by Dr. Webster, there was
complete paralysis of motion in the lower extremi-
ties, but sensibility remained;* yet there was com-
  * Med. Chir. Trans., vol. xxvi.  It had been maintained by Sir
C. Bell in the first instance, that the posterior columns of the-
cord were the channels of sensation, as the cerebellum, in his
opinion, was the seat of it; for the intimate connection of the
two tend to make it necessary that their functions should be the
same.  The experiments of Flourens and Bouillaud disproved
his views as to the functions of the cerebellum : it was then to 
32      CONNECTION BETWEEN PHYSIOLOGY
 plete  destruction of the posterior  columns in the
 lower part of the cervical region.  Similar cases
 have been  put on record  by Mr.  Stanley, and by
 Dr. W. Budd.  Dr. Nasse  of Bonn,refers to several
 cases of the same kind,  observed by  himself or
 others.*   We  have  ourselves  seen  two  cases in
 which the prominent symptom  was  great impair-
 ment of the motor power,  without injury to the
 sensitive;  yet the seat of organic lesion in both was
 in  the posterior column of the cord.  Such a case
 as  that of Dr. Webster's, appears to us to be con-
 clusive...that sensation  may be enjoyed  in the  in-
 ferior extremities independently  of the posterior
 columns."—" Nevertheless we are not aware of any
 well-observed case, in which the motor  power per-
 sisted  after extensive lesion  of  the  antero-lateral
 columns; on the contrary, we  believe it may be laid
 down as the general rule, that lesion of those columns
 always impairs  both  the  motor and  the  sensitive
 functions to an extent proportionate to the amount
 of morbid structure. Pathological observations, then,
 appear to  warrant the conclusion,  that the antero-
 lateral  columns  are  compound  in  function,  both
 sensitive and motor; but they do not justify us in
 attributing  sensitive power to the posterior columns.
 The  hypothesis, then, which  we are most disposed
 to adopt, is the following:—That the antero-lateral
 columns of the spinal cord with the gray matter,
 are, in connection with  the brain, the  recipients of
 sensitive impressions,  and  volitional impulses, and
 that they are the centres of  the independent or phy-

be expected  that  sooner or later it  would be found that the
funct.ons of the posterior cord were of the same nature as those
of the  organ with which it is connected so closely!
1835^3n6?r   UDgen ZUr P"?81010^ ™d Pathologic  Bonn, 
AND INTELLECTUAL PHILOSOPHY.       33
sical nervous actions of the cord:  and that the pos-
terior columns propagate  the  influence of that part
of the encephalon, which combines with the nerves
of volition to regulate  the locomotive powers, and
serve as commissures in harmonizing the actions of
the several segments* of the cord."!
   17.  I have now briefly described the machinery
of unconscious life:—first, we  have the Sympathetic
System (7), carrying on  the functions  of nutrition
and secretion; the maintainer of  vegetative life:—
secondly, we have the Spinal Cord, and its dependent
nerves, by which involuntary movements are effected,
and to whose agency many of the actions termed in-
stinctive may probably be referred; and thus far man
and the animal creation stand on an equal footing, or
rather the animal has the  advantage; the spinal sys-
tem of unconscious  life  being more  complete, and
less disturbed by other  influences, than in man.  We
have next to consider that organ, or rather collection
of organs which he possesses in an unrivaled degree
of perfection, and by means of which all those com-
plex mental operations are performed, which distin-
guish the human  race from  all the other inhabitants
of  the earth.   The encephalon, or parts within the
skull, may be distinguished into four chief divisions,
i.e.,  1. The Medulla oblongata.—-2. The cerebrum.
3.  The cerebellum. 4. The mesocephale*  The fol-
lowing description of the  position  and connection of
  * By a segment of the cord, must be understood the part from
which one pair  of spinal nerves proceeds.  To each pair of
nerves a ganglion or nervous centre is attached, on the posterior
root • it is possible, therefore, that these ganglia may have a
larger share than has yet  been attributed  to them, in the inde-
pendent segmentary action here alluded to
  + Todd and Bowman's  Phys., vol. i. pp. 319-321.
  \ From v-trcr, middle, and x6<f>*X»i, head. 
34      CONNECTION BETWEEN PHYSIOLOGY
the parts taken from the report made to the Royal Aca-
demy of Sciences at Paris, in 1822, by a committee
appointed to consider the experiments of M. Flourens,
may give  some notion of the  encephalon generally.
   " It is at present known, that the medulla oblon-
gata is the superior part of the spinal cord, contained
in the cranium, which also gives many pairs of nerves;
that the fibres of communication between its two
fasciculi (the pyramidal  bodies)  interlace with one
another, so that those on  the right go to the left side,
and reciprocally;  that these fasciculi,  after  having
been enlarged, in the mammiferae by a mass of gray
matter,  which forms the  prominence known by the
name of pons Varolii, separate themselves and are
called the crura cerebri, continuing to send off nerves.
They are again enlarged by  a new  mass of  gray
matter,  to form the parts commonly called thalami
optici, and a third time to form those called corpora
striata; and from the whole external edge of these
last swellings arises a lamina more or less thick,
more or less convoluted  externally according to the
species, covered  entirely on the outer surface  with
gray matter, forming what is called the hemisphere.
This lamina, after having bent back upon itself in
the middle of the convolutions, unites on the opposite
side by one or more commissures or fasciculi  of
transverse fibres, the largest of which, existing only
in the mammiferous tribes, takes the name of corpus
callosum.  It is also known that on the crura cerebri,
behind the thalamus opticus, are one or two pairs of
swellings of different magnitudes, known, when there
are two pairs  as in the mammiferous tribes, by the
name.oi' quadngeminal  tubercles, from the first  of
which-the optic nerves appear to arise; that the ol-
factory nerve is the only one which evidently does
not arise from the spinal cord or its pillars; that the 
AND INTELLECTUAL PHILOSOPHY.         35
cerebellum as  a single mass, white  internally and
cineritious externally like  the hemispheres, but often
more divided by external folds, is placed transversely,
behind  the quadrigeminal tubercles,  and  over  the
medulla oblongata, to which it is united by transverse
fibres, which go by the name of  crura cerebelli, and
which are inserted into the cerebellum by the side of
the pons Varolii."*
   In order to make  this description clearer, I shall
here refer to a plate,! showing a longitudinal section
  * Solly on the Human Brain, p. 299.
  t References to the plate, which is reduced  from Quain's
Anatomy of the Nerves and Brain, PI. ix.
  A. The internal  convolutions of the right cerebral hemi-
sphere.
  B. The corpus callosum.
  C. The anterior extremity of the corpus callosum turning
downwards towards the base of the brain.
  D. The posterior border  of the corpus callosum becoming
continuous with
  E. The fornix.
  F. The right crus of the fornix descending to
  G. The corpus mammillare.
  H. The band of white fibres passing from the corpus mammil-
lare into the thalamus opticus.
  I. The septum lucidum.
  K. The crus cerebri of the right side.
  L. The divided edge of the velum interpositum.
  M. Section of the pons Varolii through which  the ascending
fibres of N. the corpus pyramidale  are seen separated by gray
matter, as they pass onwards to the crus cerebri.
  0. The interior commissure of the third ventricle.
  P. The middle commissure (commissura mollis).
  Q. The posterior commissure.
  R. The right thalamus opticus immediately beyond which and
somewhat anteriorly lies the corpus striatum.
  T. The pineal gland.
  U. The corpora quadrigemina or optic tubercles.
  X. The processus e cerebello ad testes.
  Z. Section of the cerebellum, showing the arrangement of the
white and gray matter called arbor vita?.
    1. Olfactory nerve.
    2. Optic nerve of the right side.
    3. Third nerve (motorius oculi). 
36
CONNECTION BETWEEN PHYSIOLOGY
of the cerebrum  and cerebellum  made perpendicu-
larly between the hemispheres.
  As «ome fibres pass between the medulla oblongata
and  the cerebrum, and  others between  it and the
cerebellum, both are  thus  brought into communica-
tion  with  the  spinal cord, between which and the
above-named parts the medulla oblongata is placed.
The  mesocephale is the  part immediately  above
the medulla oblongata, the pons Varolii forming its
lower, the quadrigeminal  bodies its upper surface.
It "contains fibres passing between all  the rest of
the encephalon, as well as  some connecting opposite
sides," and  " may be compared to a railway termi-
nus,  at  which  several lines  meet, and  pass each
other."*
  18. "The whole  brain of  an  adult man (a Eu-
ropean)  varies between 3 lbs. 2 oz. and 4 lbs.  6 oz.
(troy) in  weight.  The higher grades  of intellect
being generally  accompanied  by a  proportionate
size of  brain.   Thus the brain  of the  celebrated
Cuvier  weighed  4 lbs.  11 oz. 4  dr.  30  gr. (troy),
and  that of the well-known  surgeon Dupuytren 4
lbs. 10 oz. troy:  while on the contrary the brain of
an idiot 50 years old weighed only 1 lb. 8 oz.  4 dr.,
and that of  another 40 years  of age weighed but 1
lb. 11 oz.  4 dr."  This great weight depends mainly
on  the  cerebrum and  cerebellum, the medulla ob-
longata  and mesocephale forming  not more than one-
tenth of the whole.*  The observation made  above
by Tiedemann  as to the  relative proportion  borne
by the brain to the intellect, is farther confirmed by
the fact, that  animals  of  a much larger size than
man have a much less brain;  thus the largest brain

  * Todd and Bowman's Physiol., vol. i. p. 260.
  t Tiedemann on the Brain of the Negro. Phil. Trans., 1836. 
          AND INTELLECTUAL PHILOSOPHY.       37

of a horse  weighs about 1 lb. 7 oz.—the  elephant
and whale, indeed, have a larger absolute weight of
brain;  but when considered with reference  to the
size  of the body, it will be found that the proportion
of brain is trifling as  compared with that of man—
an elephant has a brain of  about 8 lbs., and " Ru-
dolphi  found  the  brain of a whale  75 feet long
(Balxna mysticetus), to weigh 5 lbs. 10| oz.:"* an
enormous disproportion between bulk of body and
weight of brain.
  19. It has already  been noticed  that  though the
entire encephalon acts as one great  nervous center,
it must nevertheless be considered as  an aggregate
of various gangliform masses of vesicular and fibrous
matter, united together by their respective  commis-
sures or connecting bands.  Of  these masses, the
most important are the cerebral hemispheres, which
occupy the whole upper part of the skull.  A deep
fissure, extending from front to back, separates these
two bodies down to the great commissure or corpus
callosum, which unites them through their  whole
length;  and the whole surface, as well the sides of
the fissure as  the  upper part, is deeply corrugated,
so as to bear somewhat the appearance of  a pocket
handkerchief closely  crumpled in the hand.  " In
man the  convolutions of  the right and left hemi-
spheres do not present a perfect symmetry;  and it
is not a little remarkable, that in  general the lower
the development of a brain the more exact will be
the symmetry of its convolutions.  Thus the brains
of all inferior mammalia, even of those which make
the nearest approach to man, are exactly symmetri-
cal.  The imperfectly developed brain of the child
exhibits a similar symmetry; and that of the inferior
* Todd and Bowman's Phys., vol; i. p. 261. 
38
CONNECTION BETWEEN PHYSIOLOGY
races of mankind, in  whom the  neglect of mental
culture, and habits approaching to those of the brute,
are opposed to the growth of the brain, also present
a  symmetrical  disposition of the  convolutions."*
Over the whole surface, and extending into the deep
sulci of these convolutions, is spread a coating of
gray vesicular matter,  and as in the inferior animals
the sulci are fewer, and of course the vesicular mat-
ter less abundant, it would seem that the  object of
these convolutions is, to  pack the  largest  possible
quantity of this  important substance into the smallest
possible space.   The  interior part consists  of white
fibrous substance, which  is generally supposed to
act as a conductor of the nervous energy generated
in the vesicular.  Behind and below these, so as to be
connected by their overlapping lobes, we find  the
cerebellum or little brain.   It "consists of  a central
and two lateral  portions:  the former also called the
median lobe, is the primary part; it is the only part
of the organ  which exists  in fishes and in reptiles;
the lateral portions or  hemispheres are additions to
this, and denote an advance in development.   It is
in  birds  that these are first found; they are most
highly developed in mammals, and attain their maxi-
mum in man."!
   20. Having  now given a  general description of
the organs which carry on the functions of life and
intelligence, it  remains to give a  somewhat more
 detailed account of their machinery, and  to  prove
 from facts that such is really their  office:  and here
 we must enter into the melancholy details of disease
 and suffering.  For as long as all the organs of our
 bodies continue to execute their functions duly,  it is
* Todd and Bowman's Phys., vol. i. p. 283.
t Ibid., vol. i. p. 269. 
          AND INTELLECTUAL PHILOSOPHY.        39

difficult to say where the power is generated in that
nicely adjusted machine.  It is  not till we see un-
wonted effects produced on the particular nerves by
disease or  violent  injury, that  we can distinguish
their use.   It is to the reports of the hospital, there-
fore, that we must refer for proofs of the different
functions of the nervous fibres, and the influence of
the brain over them: thus it may be  noticed that in
palsy, which results from an injury within the skull,
the limbs of one side, or of the whole body, -accord-
ing as the injury is  more or  less extensive, are de-
prived sometimes  of motion, retaining  sensation;
sometimes of sensation, retaining motion*—that the
division of one nervous  trunk  issuing from the brain
will impede digestion;  of another,  will no less dis-
order respiration—that by a tumor in  one part of the
cavity of the skull, the  moving power of one side of
the  face will be destroyed, so  that the odd spectacle
may actually be seen of a man laughing with only
one side of his mouth;  in another, the sensation on
one side of the face will be so lost that the  eye
becomes insensible to the presence of offending sub-
stances, so that inflammation  ensues from an unfelt
injury, though at the same time  the other eye retains
all its sensitiveness.!
  * See Solly on the Human Brain, Part viii.
  t The following cases given by Sir Charles, then Mr. Bell, in
a paper communicated to the Royal Society, and published in
the Phil. Trans, for 1829, are so curious, and at the same time
so conclusive, that I give them at length.
  " By experiments on the nerves of the face three things were
proved.  1st. That the sensibility of the head and face depends
on the fifth pair of nerves. 2dly. That the muscular branches of
the fifth were for mastication. 3dly. That the portio dura of the
seventh controlled the motions of the features, performing all
those motions, voluntary or  involuntary, which are necessarily
connected with respiration; such as breathing, sucking, swallow- 
40       CONNECTION  BETWEEN PHYSIOLOGY
   21.  As a proof that sensation travels from  the ex-
tremities of the body along the nerves to the brain,
ing, and speaking, with all the varieties of expression.  The
occurrences which I have witnessed are,
  " 1.  A man shot with a  pistol ball, which entered the ear,
and tore across the portio dura at its root.  All motion  on the
same side of the face from  that time ceased, but he  continued
in possession of the sensibility of the  integuments on that side
of the  face.
  " 2.  A man wounded  by the horn of an ox.  The point of the
horn entered under the  angle of the jaw, and came out before
the ear, tearing across  the portio dura.  The forehead of the
corresponding side is without motion, the eyelids remain open,
the nostril has no motion in breathing, and the mouth is drawn
to the opposite side.  The  muscles of the face, by long disuse
are degenerated, and the integuments on the  wounded side are
become like a membrane stretched over  the skull.  In this man
the sensibility of the face is perfect.  The same nerve,—the portio
dura,—has been divided  in the extirpation of a tumor from before
the ear, and the immediate effect has been a horrible distortion of
the face by the prevalence of the muscles of the opposite side,
but without the loss of sensibility.
  " As to the fifth nerve the facts are equally  impressive.  By a
small sacculated tumor affecting the roots of this nerve, the sen-
sibility was destroyed in all the parts supplied by its widely ex-
tended branches; that is, in all the side of the head and face, and
the side of the tongue, whilst the motion of the face  remained.
By  the drawing of a tooth from the lower jaw, the nerve which
comes  out  upon the  chin to supply one-half  of the lip was in-
jured,  and  exactly the half of the  lip was rendered insensible.
When  the patient put his  mouth to a tumbler he  thought they
had given  him a broken glass.  A gentleman falling,  a sharp
point entered his cheek and divided the  infra-orbitary nerve (a
branch of the fifth); the effect was, loss of sensation without loss
of motion in that half of the upper lip  to  which the nerve is dis-
tributed.
  The  following is from a previous paper by the  same  writer.
" To understand the  inference from the following short narra-
tive, it is necessary to remember that the nerve in question (th©
fifth) not onjy goes through  the orbit (of  the eye), supplying the
parts contained, in it, but also extends its branches to the angle
of the  eye, eyelids, and forehead.....A few days after th«
discharge from the ear had ceased, the eye became entirely in-
sensible to the touch.  This loss of feeling extended  to the lin-
ing of the eyelids, to the skin  covering them, and to the  skin of 
          AND INTELLECTUAL PHILOSOPHY.       41

we may mention the fact that when a part containing
the termination of any nerve is amputated, the pain
felt in the extremities  of the now-shortened fibres of
that nerve is referred by the patient to the member
which in their perfect state they supplied.   Thus
when a limb, for instance, has  been cut off, the pa-
tient  not  unfrequently complains  of pain in  the
fingers which he no longer possesses.*  It is not in
fact till  experience has taught us  that a distinct sen-
sation belongs to each point of  the  body, that we
refer to  that part as the seat of the feeling.  " Under
the name  of common  or general sensibility, may be
included a variety of internal sensations, ministering
for the  most part to  the  organic functions, and to
the conservation of the body.   Most  parts  of the
frame have  their several  feelings  of comfort  and
pleasure, of  discomfort and pain.  In many of the
more deeply seated organs, no strong  sensation is
ever excited, except in the  form of pain, as a warn-
ing of an  unnatural  condition;"  nay,  it has been
observed in the case of injuries which have exposed
some of these deeply seated viscera, that the sense
of touch appeared to  be absent.   It is remarkable
that the sympathetic  system  of  nerves sends  one
fibre of its own from each  ganglion into  the spinal
system; and this it would seem, is the messenger
by which notice  is given at the mental center, of the
unnatural condition into  which any of the  organs
supplied by the ganglionic  nerves may have fallen,
the cheek and forehead, for about an inch surrounding the eye,
but it did not go beyond the middle line of the face. When she
(the patient) told me her eye was dead, (as she expressed it,) to
be certain I drew my finger over its surface, and so far was this
from giving her pain, that she assured me she could not feel that
I was touching it at all."—Phil. Trans.,  1823, p. 291.
  * Muller, p. 746.
4 
42
CONNECTION BETWEEN PIIYSIOLOG
in order that, when  this is  the case, a remedy may
be applied, so as to prevent the danger to life which
would be consequent on its continuance.
  22.  Besides this general sensibility, whose proper
organs are still  a matter of uncertainty, there are five
especial forms  of sensation, each provided with its
separate apparatus.   It is hardly necessary to say
that these are  touch, taste, smell,  hearing,  sight.
The nerves of  touch are distributed over the whole
surface of the skin,  though  some parts, such as the
palm of the hand, and the sole of the foot, receive a
larger portion of these fibrils  than are found else-
where.   This  sense "exists only in those regions
of this great system which are exposed to the contact
of foreign bodies, and where it is  essential to the
comfort or preservation of the animal that the pre-
sence  and qualities of external objects should be
perceived.  Its  nerves, unlike  those of  the  other
especial senses, which have their origin in the brain,
are derived from the cerebro-spinal system, and in-
termingle, as they pass out, with those  of motion.
The extremities of these  nerve  fibrils pass through
the true skin or cutis into small papillae which pro-
ject into, and are further defended by the cuticle, or
scarf skin, which covers them.  The furrows which
may be observed in the skin are caused by rows of
these papilla? which raise  the  cuticle, and leave a
groove  where  it  sinks  into the hollows  between
them."   These papillae are  of an average length, in
man,—of ^ of an  inch:  at their base  when  they
spring  from the  cutis they measure about T^T of an
inch in diameter, and they  taper off to  a slightly
rounded point."   Within them " a fibrous structure
is apparent," and by the help of solution  of potass
"filaments of  extreme  delicacy  are  discoverable.
Injections of the blood-vessels demonstrate the exist- 
          AND INTELLECTUAL PHILOSOPHY.       43

ence of a small arterial twig advancing up the interior
of the papilla and subdividing into two  or  more
capillary  vessels-: these, after forming small loops,
re-unite either at the base of the papilla, or in  the
subjacent texture, into small veins which empty their
blood into the  venous plexus  of the cutis.  The
vascularity of the integument is therefore in general
terms proportioned to its perfection as an organ of
touch."*
  23.  It has already been seen  that  it is difficult to
separate  the  nerves of touch from those of general
sensation, even in imagination, and yet there are  not
a few phenomena of sensation quite  independent of
this especial sense: pain especially ; which continues
to be felt  after the sense of touch is lost by palsy,
and  which affects parts to which these  nerves  are
not distributed.   The only set of nerves which  are
invariably to be found where pain is felt, are  those
of the  sympathetic system; for these belong  espe-
cially to the viscera, and send out twigs which cling
to all  the arteries:  thus  it is impossible to wound
any part of the  body without injuring some fibre of
this system:  and as it is  to it  that the functions of
vegetative life are especially entrusted, it  is perhaps
allowable to conjecture, in default of actual proof,
that it is  to it also that the business of giving notice
of any derangement in or impediment to  these  func-
tions  is  confided,  and that  the  general sensation
which  is  independent of touch, may be  referred to
these nerves.
  24.  The  structure  above described is  in  great
measure  that of  all the other nerves  of especial
sense, Avhich are limited  to their respective organs,
i. e., the  nostrils, mouth, eyes,  and ears.  Each of
* Todd and Bowman's Physiol., vol. i. pp. 404, 410, 411. 
44      CONNECTION BETWEEN PHYSIOLOGY
these organs has its own nerve assigned to it, which
receives and transmits  the  impressions belonging to
that particular sense and no other.   Every surgeon
knows that the  needle of  the operator for cataract
produces only the perception of a flash of light when
it touches the  fibrils of the optic nerve, and that pain
and sensibility to touch remain after the optic nerve
itself has perished.   The  like may be observed of
all the other nerves of especial sense.   So  far there-
fore is clear  enough; but the mode of conveying
impressions is more  mysterious, and it  is not im-
probable  that we may never arrive at  more than  a
conjectural  explanation  of it.   The  optic nerve,
when observed with a powerful  magnifier, appears
to  be formed  of innumerable minute  fibrils which
pierce through the delicate  membrane at the back of
the eyeball, called the retina,  and show themselves
on its surface,  for the most  part in the form of small
globules or papillae easily detached, and  which ap-
pear to close the ends of  the hollow fibres.   The
     PORTION OF THE OPTIC NERVE MAGNIFIED.

auditory nerve  has something of the same appear-
ance, though the fibres are less minute than those of
the optic nerve, and the points  which show them-
selves on the membrane they penetrate, differ slightly
from these in their form.  It seems probable that 
AND INTELLECTUAL PHILOSOPHY.       45
both these nerves are destined to receive impressions
from different undulatory movements, the one con-
veying the  sensation of light, the other of sound;
and though it would be presumptuous to say that
the modus operandi  can  be certainly or distinctly
stated, yet a very simple illustration may perhaps
give some notion of  it to  those who  have not time
to pursue the study further.  When  a  hollow tube
is filled with liquid, the slightest pressure at one end
is instantly  perceived  at the  other.   If,  then,  as
modern observers assert, the nerves be hollow fibres
filled with a half fluid substance which may be seen
issuing from them if divided, then it is easy to com-
prehend  that the impression made at one end of the
fibril may be conveyed through every fibril connected
with it down to the extremest point of the motor
nerves.   What the difference of structure is, which
makes this  impression in the  one instance convey
colors, in  another sounds, and, when  propagated
further, produces that irritation of the muscles which
causes movement, has as yet  eluded  observation;
but it is evident  from the result, that some decided
difference  must  exist.   Time  was,  indeed,  when
" the nerves of the senses were  looked upon  as mere
passive conductors, through which the impressions
made by the properties of bodies were supposed to
be transmitted unchanged to the sensorium.   More
recently, physiologists have begun to analyze these
opinions. If the nerves are  mere passive conductors
of the impressions of light, sonorous vibrations, and
colors, how  does it  happen that the nerve which
perceives is sensible to this  kind of impression only,
and to no others, while by another nerve odors are
not perceived; that the nerve which is sensible to the
matter of light or the luminous oscillations, is insen-
sible  to  the vibrations of sonorous bodies;  that the 
46      CONNECTION BETWEEN rilYSlOLOG
 auditory nerve is not sensible to light, nor the nerve
 of taste to  odors; while, to the common sensitive
 nerve, the vibrations of bodies  gives the sensation,
 not of sound, but merely of tremors ?   These con-
 siderations  have induced  physiologists  to ascribe to
 the individual  nerves of the senses a special sensi-
 bility  to  certain  impressions,  by  which they  are
 supposed to be rendered conductors of certain quali-
 ties of bodies, and not of others.
   " This last theory,  of which  ten or twenty years
 since no one doubted  the correctness, on being sub-
jected to a comparison with facts, was found unsatis-
 factory.   For the same stimulus, for example, elec-
 tricity, may act simultaneously on  all the organs of
 sense,—all are sensible to its action; but the nerve of
 each  sense  is  affected in  a  different way, becomes
 the seat of a different sensation; in one,  the sensa-
 tion of light is  produced;  in another, that of  sound;
 in a third, taste; while in a fourth, pain  and the sen-
 sation of a shock  are felt.  Mechanical irritation
 excites in one nerve a luminous spectrum; in another
 a humming  sound; in a third, pain.  An increase of
 the stimulus of the blood causes in one  organ spon-
 taneous sensations of light;  in another,  sound; in a
 third, itching, pain,  &c."   It is  evident, therefore,
 " that the nerves of the senses are not mere passive
 conductors, but that each peculiar nerve  of sense has
 special powers  or qualities which the exciting causes
 merely render manifest."*
   25.  It has been noticed  above, that the  immediate
 vital functions  are  carried on by the  sympathetic
 system.  In like manner, the nerves of special sense
 seem  to be connected with the instinctive emotions.

  * Muller's Elements of Physiology, translated from  the Ger-
 man by William Baly, M. D.  Sec. iv. chap. 1. 
         AND INTELLECTUAL PHILOSOPHY.        47

Any accurate observer of animals may soon convince
himself of  this.   Without insisting on the complete
exactness of  the illustration just given of the mode
in which these nerves  convey the  impressions they
receive, it may at least afford a point of view from
whence to  contemplate the operations  of  instinct.
An organ made, not only to receive, but to propagate
a particular sensation, receives it;  the shock is sent
in a moment  through the less complete, or, as in the
case of the savage, the less exercised  brain to the
motor  nerves, and movement  ensues as a necessary
consequence.  According to  Mayo, there is no evi-
dence  that  animals exert any volition beyond this
necessary contraction of the muscles consequent on
received sensation.  If  so, the actions which  we
choose to call ferocious, crafty, cowardly, &c, among
the brute creation, are wholly undeserving of this
blame.   They are feelings inseparable from percep-
tions conveyed by the organs of  smell, sight, and
hearing,  and  necessary to  the sustenance  and the
safety of the  creatures which possess them.
   26.  But  the actions  which the emotions conse-
quent on these perceptions instigate, are, in many
instances, exactly such as intelligence would suggest.
The young calf seeks the udder as soon as it is born,
but it is evident that he is merely led thither by the
sense of smell; for instead of at once reaching the
spot, he pushes  his  nose  awkwardly hither and
thither, and it is only  when his mouth is  touched,
and the nerves of another sense thus excited, that he
begins to suck. The movements of a lamb following
its mother, of a dog hunting its prey, of a bird build-
ing its nest, result in the same way from impression
on the nerves of sense.
   But although the animal actions we have  mention-
ed, when their nature  is considered, seem  to  be as 
48      CONNECTION BETWEEN PHYSIOLOGY
intelligent as if human reason had instigated them, it
may easily be proved that the  sagacity from which
they proceed is extremely limited in its extent.   For
whenever any cause leads the  animal to transgress
those bounds, it is then seen at once how different
reason is from instinct.  Such is the case of a puppy
when rubbing its nose on a brick floor to bury a bone:
of a hen sitting on a stone instead of an egg;  such
likewise was the case with the beavers which Frede-
rick Cuvier  kept in  a  cage.  These  animals,  on
being supplied with materials, employed themselves
in building that  particular structure which, essential
as it is to their existence when  at large, and in  their
natural state, was  then utterly without use or mean-
ing.
   27. The obvious  conclusion  from  hence is, that,
whatever faculty the instinctive  impulse  elicits,  is in-
capable of advancing beyond a  certain point in this
class of creatures,  and is unserviceable for any other
act of intelligence.  "Cette pensee qui se considere
elle-meme, cette intelligence qui se voit et qui s'etudie,
cette connaissance qui se  connait, forment evidem-
ment  un ordre de  phenomenes determines d'une
nature  tranchee, et auxquels nul animal ne saurait
atteindre.  C'est la, si Ton peut ainsi dire, le monde
purement intellectual, et ce monde n'appartient qu'
a l'homme.   En un mot, les animaux sentent,  con-
naissent, pensent; mais l'homme est le seul de tous
les etres crees a qui le pouvoir ait ete donne de sentir
qu'il sent, de connaitre  qu'il connait, et de penser
qu'il pense.":
   28. But though  the  animal  intelligence,  with
whatever labor  it may  be  cultivated, be  unfit for
  * Resume analytique des Observation de Frederic Cuvier sur
l'Instinct et l'Intelligence des Animaux. Par P. Flourens p. 55. 
         AND INTELLECTUAL PHILOSOPHY.       49

any speculative purpose, this defect is  compensated
for by its fitness for  practical purposes without any
previous exercise.   The  cause of this is the com-
paratively small  compass  of apparatus  connecting
sensation  with action  in  the lower tribes;  and  as
they  are thus in great measure  exempt from  the
painful apprehension of danger, and from perplexity
at the time that it occurs, it is in their case decidedly
beneficial.   In man, the relations between the sensi-
tive and motor fibres of the nerves issuing from his
brain are liable to be confused with those of higher
intelligence,  in  consequence of  the more  compli-
cated functions of that  organ.   This structure of his
nervous  system exposes him to inconvenience and
hazard, which other animals are exempt  from.  The
dizziness produced by looking down a precipice is
known to every one; were we to try to cross a
chasm on a narrow  plank, we should be  very apt to
lose our balance and fall, if unused to the situation;
yet we should walk steadily along the same  board
placed on the floor.  In this case  it is evident that
our real condition would not be changed; but that
the danger would arise entirely from  the difference
in the perception received by the eye and communi-
cated by it to the organs of intelligence.   It may be
observed that throughout the animal  kingdom  this
timidity seems to increase with the degree of intelli-
gence belonging to the  creatures placed  in  such
situations.   Goats  and ibexes stand  at  the edge of
precipitous rocks, and  gaze fearlessly on the depths
beneath; but the  carnivorous animals,  which  are
more  intelligent* than the ruminating tribes, show
considerable alarm when  exposed to this danger,
though on other occasions they are more courageous.
5
* Flourens. 
50      CONNECTION BETWEEN PHYSIOLOGY
 Cats, for example, though  accustomed to climb, are
 frightened and unsteady when put on the bough of
 a tree at any considerable  height, and there can be
 little doubt that the instability of the human frame,
 under the circumstances described, is augmented by
 the disturbed state of the reasoning  faculties arising
 from foreseeing the probability that our  alarm will
 increase.  I  am  also inclined  to think  that where
 the disturbance in the functions of the motor fibres
 is  not  caused by fear, it  arises from the  want of
 some near and steady object, by looking at which
 we may adjust the body so as  to  poise it duly.  A
 distant  horizon  with no  intermediate near object,
 such as it is in looking from a precipice;  or a rapid
 current, does not afford this, and we falter.  And
 this possibly is one cause of reeling in drunkenness:
 the functions of the optic nerve are disturbed by the
 unwonted pressure of blood on  the brain, and every-
 thing appears to  be  in  motion:  accordingly, having
nothing steady before him, the drunkard reels.  The
 narrowest ledge on the side of a precipice may be
crossed safely, by looking steadily at the rock beside
us, instead of at the chasm below.
  29. Before quitting this  part of the subject, it will
be well again to observe, that the  fibrils  which con-
verge from every part of the body,  from the trunks
of the nerves, never in any instance  unite with each
other.   Thus every one carries its report from the
part which  receives the impression, distinctly and
separately to the brain; and, as the white substance
 of that  organ, in  whatever  form it  appears, is also
 composed of minute fibres sustained and  clothed by
 a most  delicate membrane, so we have good reason
 to  suppose that the sensation carried by the finest
fibril from the remotest part of  the body,  is commu-
nicated  to its own especial fibril  ia  the  brain, and 
         AND INTELLECTUAL PHILOSOPHY.       51

through  it duly  transmitted to the  corresponding
motor fibre.
  30. But another circumstance is  here to be ob-
served.*  The sum of all the  fibrils in  the nerves
does not by any means amount to the volume of the
brain even in the lower  order of animals; still less
in man, in whom, though  the volume of the brain
be proportionally greater, the nerves are less;  thus
there must be many fibres destined to some other
purpose than that of mere conductors of sensation.
But  it is likewise remarked that they have a plexi-
form arrangement;  and thus the simple fibril of sen-
sation,  though not mixing  with any  other,  may
nevertheless, by its  intercrossing, communicate what-
ever shock it may  receive through a different series
of nerves, and so  give rise to those varieties of action
which  sometimes excite  our surprise when we see
them in the brute  creation, because they  seem to
partake of the nature of reason.  But if the reasoning
faculties be,  as I shall  presently show, the mere
function of an organ, then, in proportion  as  that
organ  is developed, its  properties will also be de-
veloped, and  it is  at the option of the  will which
directs  them to make those properties available, or
not, to other and  higher purposes than those relating
to mere animal  life.  I have  already  noticed  that
we have no proof of any will in the animal beyond
the mechanical one resulting from a shock transmitted
through the nervous circle.  Of the  will of man, as
it belongs to a  second  class  of functions, I  shall
speak by and by.
   31.  It has  already been observed, that the brain
consists of various portions,  which may  be con-
  * On Fibres of Spinal Marrow and Sympathetic in Rana escu-
lenta.  Dr. A. W. Volkman, Brad. Med. Rev., vol. vh. p. 541. 
52      CONNECTION BETWEEN PHYSIOLOGY
sidered  as  separate ganglia, each probably having a
different function, though hitherto but few of the e
functions have  been ascertained.   Ot these gangii-
form masses the cerebral ^hemispheres take the hrst
place in the importance of  their office—the cerebel-
lum probably takes the second, and next to these,
perhaps we may reckon the corpora striata and optic
thalami, for a lesion of either of these bodies is in-
variably attended with  palsy of the limbs,  so that
they appear to play an important  part among  the
animal  functions.   Both consist of gray vesicular
matter.   It has been attempted to decide with more
certainty on the office of these bodies; and palsy of
the lower extremities has been attributed to lesions
of the one—of the upper, to the other;—but  these
conjectures have not as yet been sufficiently borne
out by  facts to warrant further notice.   The func-
tions of the corpora quadrigemina, or optic tubercles,
are better defined,  at least as far as the experiments
made on pigeons by M. Flourens can be considered
to apply to other species.  In every case he  found
that  injury to  the optic tubercle  on the one  side,
produced blindness of the eye on the opposite side;
establishing thus  a  complete  decussation of  the
fibres;  and according to  his report, the removal of
these parts was attended with little or no  pain.
With regard to the office assigned to the other small
ganglia and lesser commissures, no very clear account
can be given, for their proximity to other parts renders
it impossible that the injury should be confined to
them alone: and thus symptoms become complicated,
and puzzle and embarrass  the observer.
   32.  The function  of the cerebellum was long  a
matter of dispute, no less hot than that respecting
those of the different  columns of the  spinal  cord,
and  even now in  following the opinion  of any one 
          AND INTELLECTUAL PHILOSOPHY.       53

of the contending parties, I shall hardly escape alto-
gether from animadversion.  Sir Charles Bell and
M. Foville, observing its connection with the pos-
terior column of the spinal cord, considered it as the
organ of sensation—this opinion, however, was sub-
sequently abandoned by Sir Charles Bell, who then
professed himself unable to assign any office to it.
The subject was then taken up by M. M. Majendie,
Bouillaud, and  Flourens, especially the latter, and
after a variety of experiments, always producing the
same results both in his own hands and those of the
physiologists who have  since repeated them, it seems
now to be allowed  that the deductions drawn from
them by  M.  Flourens are nearly conclusive, and
that this body must be considered as  the organ  by
which action is  co-ordinated and harmonized in the
animal frame; or, in other words, that it is the organ
of  voluntary  action, as distinguished  from  the  in-
voluntary or  reflex  action of the spinal  nerves.
M. Flourens removed  from different  birds  in turn
the cerebral hemispheres and  the cerebellum.  On
the ablation of the first, sight and hearing seemed to
be  lost, and the animal appeared without faculties;
remaining as it were  dormant, originating no  move-
ment, but if pushed, able then to use its limbs in the
usual way;  but when the  cerebellum  was removed
the results were very different, and it may be well
also to  mention, that in neither one  nor the other
case did the wounds of these parts appear  to give
any pain.*  "During the ablation of the first slices,"
(of the cerebellum), say the committee above referred
  * " The hemispheres of the brain are insensible to pain from
mechanical division or irritation : in wounds of the cranium in
the human subject, pieces  of the brain which had protruded,
have been removed without the knowledge of the patient."
Todd and Bowman's Physiol., vol. i. p. 368. 
54      CONNECTION BETAVEEN PHYSIOLOGY
 to (17), "only a little weakness and  a want of har-
 mony in the movements occur.  At the removal of the
 middle slices an almost general  agitation is the result.
 The animal, continuing to hear and  to see, only
 executes abrupt  and  disorderly movements.   Its
 faculties of flying,  walking, standing up, &c,  are
 lost by degrees.   When the cerebellum is removed,
 the faculty  of performing regulated movements has
 entirely disappeared.  Placed  on its back the crea-
 ture could  not  get  up;  yet it saw  the  blow  that
 threatened it, it heard noises, it endeavored to avoid
 danger, and made many efforts to do so without ac-
 complishing its  object.   In brief, it retained  the
 faculties of perception and of volition, but it had lost
 the power of making its muscles obey its will.  It was
 with difficulty that the bird stood up, resting upon its
 wings  and tail.  Deprived of its cerebrum  it was in a
 dormant state ; deprived of its cerebellum  it was in a
 state of  apparent drunkenness."   M. Bouillaud dif-
 fers a  little from M. Flourens, but not to any great
 extent.  " Up to this time," says he, " experiments
 only warrant us in saying that  the cerebellum is the
 central nervous organ  which  gives  to vertebrated
 animals  the faculty of preserving their equilibrium,
 and of exercising the various  acts  of locomotion.
 Besides, I think I have proved in another memoir,
 that the cerebellum co-ordinates certain movements,
 those of speech in particular, more marvelous than
 those of which we are here treating."__" If" he adds
 "the cerebellum  is only irritated, its functions  are
 not destroyed, but are  thrown  into  confusion, if I
 may so express it, for a certain time.   It  is in this
 state that we observe jumping, falling heels over
head   whirling,  and all  the puzzling movements
which  are executed with such  impetuosity that the
eye cannot  follow them.  But this  disorder, this 
AND INTELLECTUAL PHILOSOPHY.       55
species of alienation of the locomotive movements,
soon disappears when the irritation is not continued ;
so that the animal gradually regains its proper atti-
tude and normal gait.   It is  not so when the cere-
bellum is totally disorganized or entirely removed;
the animal is then forever deprived of the faculty of
equilibration, of walking, and of flying, if a bird; all
the efforts it makes are useless; they merely demon-
strate that though unable to  perform any combined
motions, out of which station or locomotion results,
it nevertheless retains the faculty of exercising partial
movements."*
   33.  A curious case is on record, which confirms
this view of the  functions of the cerebellum  as re-
gards  the human  species.   On the  post-mortem
examination of a girl, who died at near twelve years
of age, it was found that " the cerebellum was entirely
wanting,  nothing being found in  its  place  but a
quantity of serous fluid contained in  the membranes;
—a pedunculated body, not larger than a pea, was
attached  to  the corpora  restiformia;  all  the  rest
seemed replaced by the serous sac; the pons Varolii
was absent, as well as the cerebellum."—In  this
instance, it  would seem that the malformation must
have been  in  great measure congenital,  for  had it
been caused by subsequent injury,  the shock to the
constitution generally would have been too great to
allow  of the prolongation of life, even to the age she
attained.  The degree of mental and bodily power
enjoyed by this child, becomes therefore a question
of no  small interest.   " The  intellectual faculties,"
continues the  writer,!  " were obtuse, though  not to
  * Bouillaud, Recherches cliniques et experimentales tendant
Si refuter 1'opinion de M'Gall  sur les fonctions au cervelet."—
Cited by Solly.
  t Andral. 
56      CONNECTION BETWEEN PHYSIOLOGY

a remarkable degree; the answers slow and difficult;
the whole countenance  expressive of stupidity:  in
a word, the  child, though  not  exactly idiotic, still
showed a deviation  of  the mental  powers.  The
motility was also  modified;  the power  of  motion
was considerably  weakened in the  lower  limbs,
which did not possess their natural force  and vigor;
hence  the child was unable  to support  itself with
any firmness:  it  fell down frequently; the  legs'
crossed each other during walking, and the gait was
irregular and unsteady.  At  length  the  child  was
compelled to confine itself altogether to bed, and
after some time was unable to stir, even when lying
in a horizontal position;—to this were joined epi-
leptiform convulsions, which continued for some time,
and finally carried off the  patient.   The sensation
of the integumental  covering was not modified  in
any way whatever.  There was no increase of sen-
sibility in  the commencement, no  obtuseness  or
diminution of feeling, even when paralysis was most
complete; the  senses also remained  intact.   The
child could see, hear, and taste in a perfect manner.
The functions of nutrition,  of circulation,  and respi-
ration  were  carried on without any notable disturb-
ance."  However, the child  is  mentioned as  being
.weak and delicate  in constitution.
   34.  The  progress of  development in the brain of
infants affords a farther confirmation of the view
taken by M. Flourens, of the functions of the cere-
bellum in co-ordinating the  voluntary movements.
"That this  power is mental, i. e., dependent on a
mental operation for its excitation  and  exercise,"
observe the  authors of  the Physiological Anatomy
.of  Man, " is rendered probable  from  the  experience
■of  our own  sensations,  and  from  the fact that the
perfection of it requires practice.   The  voluntary
jnovements  of a new-born  infant, although perfectly 
         AND INTELLECTUAL PHILOSOPHY.       57

controllable by the will, are far  from being co-ordi-
nate ; they are on the contrary remarkable for their
vagueness and want of definition.  Yet all the parts
of  the  cerebro-spinal centre are well developed,
except the cerebellum and the convolutions of the
cerebrum.   Now the  power of co-ordination  im-
proves earlier and more rapidly  than the intellectual
faculties;  and we find in accordance with Flourens'
theory, that the cerebellum  reaches its perfect de-
velopment of form  and structure at a much earlier
period  than  the hemispheres  of  the  cerebrum."
From all this it seems clear that the cerebellum is
requisite to the execution of all pre-arranged  move-
ments, and in proportion as the cerebrum increases
in bulk and complexity, the cerebellum receives  a
similar augmentation,  so  that they  would  seem
always to have  a  certain  relation  to  each  other.
After demonstrating what are the  functions  of the
cerebrum, I shall return to the mutual relation of the
two.
   35.  The proof of the function of any organ must
be  of two kinds;  first,  it  must be  demonstrated
that when the function  is  performed  in its greatest
perfection, the organ  is proportionably developed:
secondly,  it  must  be shown that  a lesion  of this
organ impairs the function which it is supposed to
fulfill.  Both kinds of proof may be given, that the
functions of the cerebral hemispheres  are those of
intelligence.   The  following sketch shows the pro-
portion which these bodies bear to  the rest of the
encephalon in different classes of animals: the part
above the dotted line  is that which answers  to the
cerebral hemispheres.
   It is evident therefore as  has been  remarked* by
  * Owen on Structure of the Brain in Marsupial Animals, Ph.
Tran. 1834, p. 358—1837, p. 89. 
 Oo      CONNECTION BETWEEN PHYSIOLOGY

 physiologists, that the development  of the  hemi-
 spheres of the brain proceeds step by step with the
 development of intelligence through the successive
classes of the animal kingdom till it  arrives at per-
fection in man.   " Who has  not seen," says Dr.
Fletcher,* " artificially educated horses, dogs, lions,
CUTTLE.   CONGER.    TURTLE.     BUZZARD.
MARMOT.       SHEEP.        OTTER.
* Physiology, Part III. p. 89. 
AND INTELLECTUAL PHILOSOPHY.        59
pigs,  elephants, bears, monkeys, canary-birds, and
even hens;  but who has ever seen, or ever will see,
an educated worm or oyster?  The educability of
animals, then, or in other words their intellect, is in
proportion  to  the size and  composition  of their
brains."  Thus, of all animals, man, who  has  the
largest and  most complicated brain  is the most  im-
provable ; he can judge, compare, discriminate,  and
remember all the impressions  made on his senses
with far more precision than any other of the mam-
malia.   This was- to  be expected from the structure
of his brain, which differs in many points from all
others; but here a most important fact presents itself.
With the development of the brain in the animal,
proceeds also its intelligence;  but the individuals of
each  class retain a close resemblance to their com-
mon type;  the greatest difference that can be pro-
duced  by  education  between  the wild  and  the
domesticated animal  is so small as scarcely to be
worth the  notice; since it consists in little else than
a sensation of fear impressed  by the felt  power of
man: but when we look at the human race, so great
is the difference  between civilized and uncivilized
man, that  some physiologists  have endeavored to
find  in  the brain of  the latter a resemblance to the
quadrumana rather   than to  his  more cultivated
brethren.   Yet there is no perceivable distinction in
the  cerebral organs  of individuals constituting the
most clearly defined varieties  of the  human race.
Whether civilized or uncivilized, male or  female,*
  * " Although Aristotle has remarked that the female brain is
absolutely smaller than the male, it is nevertheless not relatively
smaller compared with  the body: for the female body is in
general lighter than that of the male. The female brain is for
the most part even larger  than the male, compared with the
size of the body. 
60      CONNECTION BETWEEN PHYSIOLOGY

we find the same component parts, the same relative
proportion  of brain.   Whence then the immense
difference between the negro  in his African wilds,
and the European philosopher?
   36.  I think some of the points I have endeavored
to establish will in great measure explain this. Every
bodily  fibre  acquires strength  by  exercise:   none
need be told how much muscular power is acquired
by a constant and moderate exertion:  the practised
eye will see,  the  practised  ear hear, what these or-
gans when unpractised distinguish with  difficulty; it
is not wonderful then, if the practised brain can also
carry on its  functions with greater  facility and in-
creased power.  In savage life, where subsistence is
hardly obtained, and where danger is always at a point
that keeps the emotions  which guard  existence in
constant exercise, men who have to struggle for their
daily food, and defend themselves from  their no less
daily perils, require from  the brain but  a very small
part of  what it can accomplish: their greatest stretch
of  reasoning  extends  not beyond the  connecting a
bent twig, or  a down-trodden leaf, with  the steps of
their prey or their enemy.   In such instances, we
  " The different degree of susceptibility and sensibility of the
nervous system seems  to depend on the relative size of the
brain as compared with that of the body.  Children and young
persons are more susceptible, irritable, and sensible than adults,
and have a relatively larger brain. The degree of sensibility in
animals is  also  in proportion to the size of the brain.  Mam-
malia and birds  have a larger brain and are more susceptible
than amphibious animals.
  " The brain of a negro boy 14 years old weighed, according
to Soemmering, 3 lbs. 6 oz. 6 dr. troy.  The brain of another
handsome tall negro about 20 years of age weighed 3 lbs  9 oz
4 dr. troy.  Sir Astley Cooper gives the weight of the brain of a
large negro 49 oz.  The general weight of the brain of man is
from 37 to 52 oz."—Tiedemann on the Brain of the Neero  Phil
Trans.. 183fi                           J  w-"c5'"»^"»« 
AND INTELLECTUAL PHILOSOPHY.       61
may easily conceive that  the  unexercised  faculties
become as powerless as the limb of an animal which
from the moment of birth had been restrained from
movement.  A child who had grown up with a limb
so disabled, would not be  aware of its use unless he
saw it exemplified in others, and even if he saw its
use, he would still find  that in his OAvn case the effort
to make it available would be perfectly vain.
   37. Such I conceive to be the state of the brain
which has  never been  called to exercise the higher
faculties.   The instinctive emotions are propagated
through it  with the almost delirious violence which
characterizes the brute creation, because the fibres
destined to carry on the higher reasoning functions
have remained inert till they have become power-
less, and man is thus assimilated to the lower tribes,
not because the organ of thought is wanting, but
because it has not been exercised.  Christophe, the
negro  ruler  of  Haiti, was  probably  not  removed
above a generation  or  two from the African savage,
yet his daughters were polished and accomplished
women, fit to take their place in European  society.
A better proof could hardly be given of the improy-
ability of all the races  of men by education, even in
one generation.
   38.  It now remains  that I give the  second part of
my proof, and  show that a  lesion of the  cerebral
hemispheres impairs the functions they are supposed
to fulfill, i.  e., that of  intellectual perception.   And
here I must  notice that a  considerable analogy may
be traced between the  arrangement of the brain and
that of the  organs of  special  sense.  Thus as we
have two eyes,  two ears, two nostrils: so we  have
also two hemispheres of the brain, and we  may re-
mark as a  consequence of this, that a  serious injury,
amounting nearly to the removal of one hemisphere, 
62      CONNECTION BETWEEN PHYSIOLOGY
does not necessarily abolish the functions of thought,
any more than  the loss of one eye or the  failure of
one ear produces absolute blindness or deafness.   I
have heard  an  instance of a  young  boy who was
dashed on the ground by a fall from his horse, with
such violence as to shiver one side of his skull, and
a large quantity of the brain, nearly amounting to the
magnitude of one hemisphere, actually issued  from
the wound.  AVhen this  youth had  recovered,  he
was  so far from manifesting  any want of  intellect,
that  he attained considerable  proficiency in  mathe-
matics.  This case runs parallel with that of persons
who have gone  on for a considerable  time deriving
their sight from one eye, and quite unconscious that
they had not the use of the  other.  Such  cases are
to  be met with frequently in  medical  books ;  and it
appears from what has been observed with  regard to
animals, that "where a portion of the brain is re-
moved,  its place is -supplied  by new matter; but
whether this becomes true cerebral substance," it is
added  by the  writers  already frequently quoted,
" future researches with good  microscopes  must de-
termine."
   39.  The actual removal of  a portion of  the  cere-
bral hemispheres may  take place, therefore, without
ill  consequence, unless  inflammation  should follow
in  consequence : but compression, which  prevents
the movement  of the  fibres, and consequently the
transmission of impressions, produces  total insensi-
bility.  "Sir A. Cooper used to relate in his lectures
on surgery one  of the most interesting and  unique
cases on record.  A  man  was pressed on board one
of his majesty's ships early in the late revolutionary
war.   AVhile on board this vessel in the  Mediterra-
nean he received a fall from the yard arm, and when
he was picked  up  he  was  found to be  insensible. 
          AND INTELLECTUAL PHILOSOPHY.       63

The vessel soon  after making Gibraltar, he  was
deposited in a hospital in that place, where  he re-
mained for some months, still insensible;  and some
time after he was brought from thence to a depot for
sailors at Deptford.  While he was at Deptford, the
surgeon, under whose  care  he was, was  visited by
Mr. Davy, who was then an apprentice at this  hos-
pital : the surgeon  said to Mr. Davy, ' I have a  case
which I think you  would like to see.  It is a  man
who has  been insensible for many  months; he lies
on his back with very few signs of life; he breathes,
indeed, has a pulse, and some motion in his fingers;
but in all other respects he is apparently deprived of
all powers  of  mind, volition, or  sensation.'   Mr.
Davy went  to see  the  case, and  on examining the
patient found a slight depression on one part of the
head.  Being informed of the accident which  had
occasioned  this depression, he  recommended  the
man to be sent to St. Thomas's Hospital.   He  was
placed under the  care of Mr. Cline, and  when he
was first admitted into  the hospital,  I saw  him lying
on his  back, breathing  without any great difficulty,
his pulse regular, his arms extended, and his fingers
moving to and fro to the motion of his heart, so  that
you could count his  pulse by this motion of his fin-
gers.   If  he wanted food he had the power of mov-
ing his lips and tongue; and this  action was the
signal  to  his  attendants  for  supplying this want.
Mr. Cline on examining his  head found an obvious
depression; and thirteen months  after the accident
he was carried into the operating theatre,  and there
trephined.   The depressed portion of the  bone  was
elevated  from the  skull.  While he was  lying on
the table motion of  his fingers went on during the
operation, but no  sooner  was the  portion of bone
raised than it ceased. The operation was performed 
64      CONNECTION BETWEEN PHYSIOLOGY

at one o'clock in the afternoon; and at four o'clock,
as I was walking through the wards, I went up to
the man's bedside and was surprised to see him sit-
ting up in his bed.   He had raised himself on his
pillow.  I  asked him  if he  felt  any  pain, and he
immediately put his hand to his head.   This showed
that volition and sensation were returning.  In  four
days from that time the man  was  able to get out of
bed, and began to converse; and in a few days more
he was able  to tell us  where he  came from.   He
recollected  the circumstance  of  his   having  been
pressed, and carried  down to Plymouth or Falmouth;
but from  that moment up to the time the operation
was performed  (that is,  for a period of thirteen
months and some days), his mind had remained in
a perfect state of  oblivion.   He  had  drunk, as it
were, the cup of Lethe; he had suffered a complete
death as far as regarded his mental and  almost his
bodily powers ; but by removing a small portion of
bone  with the saw, he was  at  once restored to all
the  functions of his mind, and almost all the powers
of his body."*
  40.  When death supervenes  from furious mania,
it is usually found on examination that the cortical
substance is in a state of inflammation if not of gan-
grene. The following cases  are  selected from  the
records of the hospital  of La Salpetriere at Paris.
" A woman of advanced age but strong constitution
was brought to this  hospital  October 20, 1821, by
order of the police.   She was in a state of extreme and
furious agitation; her eyes were brilliant, her excla-
mations violent: her delirium  was  upon air subjects,
but there were no means of ascertaining what  had
been the  cause or what -the  commencement of  this
• Solly on the Human Brain, p. 334. 
AND INTELLECTUAL PHILOSOPHY.        65
attack of furious mania.  For six months it continued
without the least interval of calm; but on March 13,
1822, this woman, so restless  the  evening before,
was stretched on her  bed without the power of ris-
ing:  she was  calm, her face pale and  yellow, her
eyes fixed and half open, her head bent to her left
shoulder, her respiration stertorous, her pulse  hard
and quick.  At night she had  again a paroxysm of
violence during which she  struggled and fell out of
bed.  The next day the  symptoms were still more
serious, her  whole left side was paralyzed ;  on the
third day the stupor \increased  and in the night she
died.
  " The post-mortem examination presented the fol-
lowing  appearances.  The cranium itself was much
injected with blood of a dark color:  the  meninges
were healthy, but  raised by a considerable  quantity
of serous fluid beneath: when the membrane was
removed, the periphery of the organ was found much
injected with blood, and the gray matter when care-
fully examined was of a scarlet color in the  upper
convolutions, and marked here and there with dark
spots  (ecchymoses)  in the  lateral  convolutions.
These dark spots penetrated through the white sub-
stance beneath; and the center of the right  hemi-
sphere, and  especially the corpus striatum,*  were
entirely disorganized.   The posterior  lobe of this
hemisphere was  wholly converted into a  greenish-
purulent matter which escaped on the removal of
the membrane and left  a considerable cavity, the
sides of which were covered with small  pieces of
disorganized white and gray matter  The left hemi-
sphere, though much injected with blood, had suffered

  * Palsy follows almost invariably on a lesion of this part, which
lies beneath the  hemispheres.
6 
66      CONNECTION BETWEEN PHYSIOLOGY

no  disorganization."   Here it  is evident  that  the
mania had been the result of the inflammation which.
had at last terminated in gangrene, and which, when
it reached the corpus  striatum, produced paralysis,
of the contrary side as usual.  In  another case in
the same hospital we  find a woman after an attack
of furious mania gradually losing her memory, till
at last she sunk into a state of utter  imbecility.  She
died about seven years after her admission, and on
examining the brain, it was found that the convolu-
tions of the hemispheres had entirely coalesced into
an even surface, over which a very thin layer of gray
matter  was  spread.  The  white medullary matter
was  changed from a  soft  substance into  a strong
elastic fibre, which admitted of being torn into long
strips, and offered considerable  resistance  to  the
knife of the operator.* Examples of this kind might
be multiplied from the records of La Salpetriere, but
as they all present nearly the same  appearances of
inflammation and  gangrene, with induration  of  the
white matter if the inflammation has continued long
previous to the fatal termination,—it seems needless
to quote more.   Two other cases of rather a different
nature may be added from other sources: the one of
a person possessing enough of  recollection to be
employed in  trifling commissions, but idiotic in  re-
gard to connection of  ideas : whose brain was found
on examination  to  be  without the  great transverse
band which unites the two hemispheres : and a third
where, in an idiot girl who died at fifteen years of
age, the  two anterior lobes, the parts, namely, which
form the front of  the  hemispheres, were entirely
wanting: indeed, in all cases of idiocy, the brain  has
been found exceedingly small in size, and generally
* Pinel, Jun.  Physiologie de l'Homme. 
          AND INTELLECTUAL PHILOSOPHY.        67

but slightly convoluted;  for it would seem that this
part of the brain only acquires its full size and im-
portance when the cultivation of the mind has called
it into activity.  In early childhood the convolutions
of the brain are very imperfectly developed, and their
increase  in size goes  on  simultaneously  with the
advance  of mental power—if this increase be im-
peded, or if some congenital defect prevent the further
growth of the convolutions, the mental powers are of
the lowest and feeblest kind ;"* and as this important
period, in which the organs for future  use can be
fashioned  and enlarged, terminates at  about the
seventh  or eighth year,  some notion may  hence be
formed of  the cruel wrong done  to the individual if
these precious years, in which the future  sage or hero
is  to be  prepared for his work, be suffered to pass
without culture and without that rational exertion of
the higher faculties which alone  raise the human ani-
mal above the brute.   When the brain and the skull
can receive no further development, it is late to begin
the work  of rational education,  and he  is happy
whose mother has not merely sung the lullaby of his
infancy,  but has laid the  foundation also of future
greatness,  by gently exercising  the  faculties  which
call the  material organ  into exercise without over-
tasking it; affording it the full  play requisite  to its
development without the unhealthy strain  of school
lessons while the young brain is too tender to bear it.
   41.  It would not be  difficult  to multiply  cases
where either original imperfection or subsequent in-
jury of the cerebral hemispheres  has caused either
idiocy or madness;  but  perhaps a more remarkable
proof yet of the office of the brain may  be found in
the circumstance thatt a slight degree of inflammation
* Todd and Bowman's Phys., vol. i. p. 363.
t Solly on the Human Brain, p. 370. 
68      CONNECTION BETWEEN PHYSIOLOGY

is attended by an extraordinary increase of the vivid-
ness of the ideas and the general powers of the mind.
In two cases which  have  been mentioned to me,
where I can  have no doubt as  to the fact, persons
previously of rather weak intellect, during an access
of what  is called brain fever, suddenly acquired a
mental force which abandoned them again on  re-
covery ;  and a friend  who  has suffered more than
once from  transitory inflammation  of this part has
assured me  that during the severest paroxysms of
pain,  the gratification at the  immense power of mind
thus acquired, almost counterbalanced the suffering.
  42.  Something of the same  kind occurs under the
stimulus  of wine.  A more than ordinary circulation
of blood is promoted  by it;  the brain partakes of
the excitement, and the imagination and the emotions
are thus mechanically rendered more vivid; but when
pushed to excess the vessels  become overloaded, and
if carried a step further, apoplexy and death ensue.
There is indeed no symptom of drunkenness which
does not  run  parallel with those of diseased brain ;
from the  exaltation  of  faculties  in the early inflam-
matory stage, to the utter senselessness of the  fatal
termination.
  43.  With these facts before us, and the* hundreds
of others that might be added to them, it would be
difficult to avoid the conclusion that recollection and
the power of combining ideas, or what are usually
termed the reasoning faculties, are as much a function
of the hemispheres of  the brain as sight or hearing
are of the optic or auditory nerves ;  nor can I better
sum up this part of my subject than in the words of
the  authors  already frequently quoted.t   " Thus
* Miiller, B. III. sec. v. p. 835.  Fletcher, Part III. p. 100.
t Todd and Bowman's Phys., vol. i. p. 364. 
          AND INTELLECTUAL PHILOSOPHY.       69

anatomy leads to the conclusion that the operations
of the mind are associated with the convolutions.
These parts, in the language of Cuvier, are the sole
receptacle in which  the  various sensations may be
as it were consummated,  and  become perceptible to
the animal.   It  is in these that all sensations take a
distinct form, and leave lasting traces of their impres-
sion ; they serve as a seat to memory, a property by
means of which the animal is furnished  with mate-
rials for his judgments.   When the membranes of
the brain are in  a state of inflammation, disturbance
of the mental faculties is an invariable accompani-
ment, to an extent proportional to the degree of cere-
bral irritation, and more  especially so when  the
inflammation is  seated in the  pia matert of the con-
volutions.  It is  plain that in such a case the delirium
arises from  the altered state of the circulation in the
gray matter of the convolutions, the blood-vessels of
which are immediately derived from those of the pia
mater, so that one  cannot be affected without the
other likewise  suffering.   We learn from the most
trustworthy reports of the dissections of the brains of
lunatics, that there is  invariably found more  or  less
disease of the vesicular surface, and of the pia mater
and arachnoid  in  connection with  it,  denoted by
opacity  or thickening of the latter, with altered color
or consistence of the former.   From these premises
it may be laid down as  a just  conclusion that the
convolutions of the brain  are the center of intellectual
action, or more strictly, that  this  center consists in
that vast sheet of vesicular matter which crowns the
convoluted surface of the hemispheres.   Every  idea
of the mind is associated with a corresponding change
in some part or parts of  this vesicular surface ;  and
* The covering membranes. 
 i'O      CONNECTION BETWEEN PHYSIOLOGY

 as local changes of nutrition in the expansions of the
 nerves of  pure sense  may give rise  to  subjective
 sensations  of vision or hearing, so derangements  of
 nutrition in the vesicular matter of the surface, may
 occasion analogous phenomena of thought, and the
rapid development of ideas, which, being ill-regulated,
 or not  at all directed by the will, assume the form
of delirious raving.  The action of  the  convoluted
surface of the brain, and of the fibres connected with
it, are altogether of the mental kind.   The physical
changes in  these  parts give rise to a corresponding
manifestation of  ideas;  nor is it  likely that any
thought,  however simple,  is  unaccompanied  by
change in this center."
  44. It has already been seen that  the cerebellum
in animals  acts  as the co-ordinator of movements,  so
as to rationalize them as it were;—and having now
traced the functions of the cerebral hemispheres  in
man, it is  easy to perceive  that a more complete
organ would be requisite for the execution of its
mandates.   Accordingly  we  find the cerebellum
proportioned  to its work; and the  most difficult
movements are  arranged and executed with the most
beautiful precision in compliance with  the directing
will:  yet  as  the movements which  result  from
thoughts which have  previously  been propagated
through the cerebrum, are in  some cases slow, a
provision has been made for the safety of the animal
by the  spinal apparatus, whose nerves act independ-
ently of the mind, and whose  movements  are carried
on at times unconsciously, and always without re-
quiring  attention.   Thus the  start  which  avoids
danger  precedes  the  deliberate precaution which
might come too late.  Whoever has noticed the dif-
ference between walking on mechanically, or picking
his way for a smooth or clean path, will comprehend 
AND INTELLECTUAL PHILOSOPHY.
what I  mean by the  two different kinds of action.
In manual operations, too, which are carried on from
habit, such as executing a piece of music by rote,
the slight pause which occurs if the performer recol-
lects himself suddenly, and turns his attention to the
music, shows  that thought is slower than  the  mere
habitual action which  probably is carried on merely
by the nerves immediately in connection,  and goes
no further perhaps than  the segment of the spine in
which they are imbedded.   Should M. Bouillaud's
conjecture  that the movements of speech also, are
arranged through  the medium of the  cerebellum,
prove well founded—and this is in some degree sup-
ported by the case given above  (33), where "the
answers were slow and difficult," and  by the fact
that in  infants the power of  speech is absent while
this part remains imperfect,—we  shall at once see a
cause for its large size  as compared with  all  other
parts, excepting those charged with  the yet  more
important functions of thought.
  45. We have now traced the machinery by which
man is a living, a sentient, and an intelligent animal.
We will next proceed to investigate  what may be
called the elementary  functions of intellectual man:
and  these may be divided into   two  great  classes,
distinguished by their causing or not causing bodily
change by their exercise.  They may be  thus ar-
ranged in a tabular form.
  I. Functions sharing in or causing bodily change:
     1. Appetites and  functions appertaining to life—
       Sympathetic System.
     2. Instinctive emotions—Nerves  of sense and
       medulla oblongata.
     3. Faculties—Hemispheres of the brain.
  II. Functions neither sharing in nor causing bodily
change: 
72      CONNECTION BETWEEN PHYSIOLOGY

     1.  Individual consciousness, including  the me-
       mory which this requires.
     2.  Intelligent will.
  It cannot be disputed that a  vital appetite, such
as hunger, or that an instinctive emotion, such  as
fear or grief, or that the exertion of such faculties as
those used in abstract reasoning, are attended with
bodily change.  Thus, an unsatisfied appetite causes
uneasiness ; or an instinctive emotion while the body
is under its  full  influence, sometimes acts as an an-
tagonist to appetite, as when grief  subdues  hunger
by deranging the digestive powers.   Sometimes  the
emotion interferes with the most delicate operations
of the sympathetic system, as when  fear or joy,
which necessarily arises from an impression on some
nerve of sense, affects the action of the heart through
the medium  of  the  connecting links  between  the
spinal and sympathetic nerves; there is then a sen-
sation as of a blow or compression  of  the chest:  or
when yawning tells of the general weariness of mind
and body.   Here a particular nerve acts on the dia-
phragm, the respiratory muscles are  tuned in accord-
ance  with this  by other nervous  fibres connected
with it at  its origin, and the impulse is propagated
through the whole of these  muscles.  Again, who-
ever has  ever devoted his hours  to severe study is
most probably well  acquainted with the headache
and weariness which result from it,  showing plainly
that bodily organs  have been employed in the pro-
cess.
  46. I cannot pass  over this part of the  subject
without drawing from it one useful  lesson upon  the
necessity of cultivating the higher faculties far more
than is yet done even among races calling themselves
civilized.  If the  instincts, or as some will call them,
passions,  assume so undue an ascendency in conse- 
AND INTELLECTUAL PHILOSOPHY.
73
   quence of the inertness of the antagonist part of the
   brain, that  man's whole moral  nature  falls into the
   morbid state of a convulsed, or finally a contracted
   limb, it is then no light crime in those who have the
   government of a family or of  a society of human
   beings, if they suffer the young to grow up without
   duly developing the full powers of a  nature so ad-
   mirable where  its mental growth  is  duly propor-
   tioned,—so  tremendously  capable  of  evil when it
   is not.
      47.  A man is not to be considered as  educated
   because some years of his life  have been spent in
[   acquiring a  certain proficiency  in the language, his-
   tory, and geography of Greece  and Rome, and their
   colonies, or in bestowing a transient attention on the
   principles of mathematics  and  natural philosophy;
   nor is  a woman to be considered as educated because
   she can execute a difficult  piece of music  in a bril-
   liant style, or  speak French, German, or Italian with
   fluency.  Such attainments require little more than
   mere mechanical recollection,—the lowest of all the
   cerebral faculties, or  the rapid transmission of an
   impulse from  the sensitive optic nerve to the motor
   ones of the  arms and fingers, which is nothing better
   than the instinctive movement of the animal: neither
   can the storing up the opinions of others,  or the ac-
|   customing  the tongue to the  idioms  of other lan-
   guages, be properly termed an act of thought: for in
   such  cases the  capacity  of  combining  ideas, of
   weighing and judging ere a  course  of  action  is
   adopted, remains even less exercised than in those
   who, though they are turned into the world with  the
   mind as it  were a tabula rasa to  receive any im-
   pression, and  too frequently a bad one, yet amid the
   difficulties and sufferings of poverty, sometimes learn
   to think. It is from the depths  of man's interior life
        7 
74      CONNECTION BETWEEN PHYSIOLOGY

that he must  draw what separates him from  the   *
brute, and hallows his animal existence; and learn-   ;
ing is no farther valuable than as it gives a quantity   ■
of raw material to  be separated  and worked up in
the intellectual laboratory, till it comes forth as  new
in form and as increased in value,  as the porcelain
vase which entered the manufactory in the shape of
metallic salts,  clay, and sand.
  48. I have  before alluded  to the  notion of some
physiologists that the negro formed but the connect*   i
ing link  between the baboon and man.   This  has
been so fully refuted by Professors Tiedemann *  and
Owen,t that it is needless to go into it at length; but   .
I mention it here  to give a further instance of the
necessity of cultivating the mind, even to give  the   7
bodily frame its due development, and the duty there-   ■,
fore, which even political economists must acknow-   T
ledge, of bestowing on all  the power of  doing so.   ;
Dr. Pritchard, in his  researches  into  the physical   ,
history of mankind, quotes a fearful instance drawn
from the  early history of Ireland, of the deterioration
consequent on such a degree  of poverty and suffer-
ing as reduces man  to a merely instinctive existence.
  49. " On the plantation of Ulster," says the writer,
"and afterwards on  the successes of the British
against the rebels of 1641 and  1689, great multitudes
of the native Irish were driven from Armagh and the
south of Down, into the mountainous tract extending
from the barony of Flews  eastward to the sea; on
the other side of the  kingdom the  same  race were
expelled  into Leitrim, Sligo, and Mayo.  Here they
have been almost ever since  exposed to  the worst
effects of hunger and ignorance, the two great brutal-

          * Phil. Trans., 1836, p. 497, &c.
          t Trans. Zoo. Soc, vol. i. p. 368. 
AND INTELLECTUAL PHILOSOPHY.       75
izers of the human race.   The descendants of these
exiles are now distinguished physically from their
kindred in Meath and in other districts where they
are  not in a  state of physical degradation.   They
are  remarkable for  open, projecting mouths, with
prominent teeth and exposed gums.  Their advancing
cheek bones and depressed noses bear barbarism in
their very front.   In Sligo and the northern Mayo,
the consequences of two centuries of degradation and
hardship exhibit themselves in the whole physical
condition of the people, affecting not only the  fea-
tures, but the frame, and giving such  an example of
human deterioration from  known  causes, as almost
compensates, by its value to  future ages, for the  suf-
fering and debasement which past generations have
endured in perfecting the appalling lesson.  Five feet
two  inches on an average, pot-bellied, bow-legged,
abortively featured, these  spectres of a people  that
were once well grown, able-bodied, and comely, stalk
abroad into  the  daylight of  civilization, the annual
apparitions of Irish ugliness and  Irish want.   In
other parts of the island, where the  population  has
never undergone the influence of the  same causes of
physical degradation, it is well known that the same
race furnish the most perfect  specimens of human
beauty and vigor both mental and bodily."
  50. If such be the effect under  our own eyes of
reducing man to the lowest point at which he  can
maintain even a mere animal existence, we may well
believe that ages of such a state may have  stamped
many of the  characters of the brute  creation on the
human  countenance in the  wilds of Africa.  The
jrreat difference between the skull of the negro  and
the  European consists  in the wide opening for the
nose, which by its greater  spread affords more room
for the development of the olfactory  nerve; and we 
76      CONNECTION BETWEEN PHYSIOLOGY

may add to this, the form of the jaw again approxi-
mating to the animal in its projection, though not in
its other characters.  We may probably read in these
peculiarities the history of generation after generation
doomed to a merely instinctive existence, as  well as
we read sensual indulgence in the thick, moist, swelled
lips which so frequently characterize those who give
themselves up to such a course of life.
  51. It is almost needless to observe, after what I
have  already  said, that  it is  to  the  surplusage of
fibres in the brain over and above the quantity re-
quisite for the transmission of sensation to  the ap-
propriate  motor fibre, that we must trace not only
the power of  reasoning, but  all the finer  flights of
imagination  and wit.  The  agent of which I shall
now presently have to speak, appears able at will to
reproduce the  impressions  once received through
the medium of the nerves of  sense, and it is amid
the novel combinations of the  fibres thu» called into
action, that all  those  wonders of thought  are  pro-
duced which have  won our admiration  through all
ages.   That such is their  origin may be proved by
the fact, that the  most brilliant imagination never
yet produced  anything which had  not been seen,
heard, or felt, as it were piecemeal:  the combination
is new, but the material thus woven afresh is what
all are acquainted with.

  52. We have now traced the human animal through
all parts of his structure:  we have shown first a sys-
tem of ganglia and nerves  springing from them, by
means of which organic life is  carried on, and appe-
tites  excited for its maintenance:  we have further
seen a set of  nerves  whose terminations are to be
found at the  base of the brain, which supply  the
senses by which man communicates with the exter- 
AND INTELLECTUAL PHILOSOPHY.        77
nal world:  we have seen another apparatus within
the cranium by which these sensations are weighed
and examined,  and the result of this examination
transmitted finally to the motor nerves for execution ;
altogether forming  the most perfect  piece of  ma-
chinery ever constructed: for these nice operations of
thought are  the work of fibres and fluids  contained
in them  merely set in motion  by the impression
made  at one part, and thus transmitted through  the
whole series.   Let us now consider  the  actions of
this animal.
  53.  The first  instinctive  impulse is to preserve
life.   Look at a wrecked vessel!   There is one man
there  ordering and directing all  on  board: the only
remaining boat is  lowered; he  is  careful to see it
filled  with  the  persons  crowded  about him,—it
pushes off, and where is  he ?   He is there  on the
deck of that sinking ship;  the boat would not hold
all, and he has refused a  place  in it, and remained
to perish rather than sacrifice  one life committed to
his  charge.  He knows that death awaits him: he
has been urged to  save himself,  and yet he is there!
What is the impulse  which prompts him thus to
contravene the first great law of animated nature ?
  54. Sleep again is among our  most  imperious
needs, for  the want of it gradually destroys life.
There lies a sick man in his bed, senseless,—in the
last stage of an infectious  fever:  and there  is  one
watching beside  him, looking  pale and exhausted,
but who sleeps not, stirs  not, though her young life
is wasting away with  fatigue, and exposed to conta-
gion : and she knows  it, and has calculated that the
same grave will receive  both!   What nerve of all
that fine machinery has impelled her  to this course ?
  55. Look at the Astronomer  in  his observatory!
The  night  is far  advanced, and he  is chilled  and 
 78      CONNECTION BETWEEN PHYSIOLOGY

 fatigued; yet he remains with his  eye at the tele-  *
 scope__for what ?  To carry on a series of observa-
 tions which  perhaps in two  generations  more may  .1
 give as its result the knowledge of some great law  ">
 of the material universe : but he will be in his grave  I«
 long ere he can expect that it will be ascertained.  it-
 He sits down to his calculations, and he forgets his  s
 meals, sees nothing, hears  nothing, till his problem  J<
 is solved!  No  sense prompts him to this sacrifice  fl
 of rest and comfort.  But do  we call these persons
 insane ?   No—we  honor them  as  the  excellent  of  \
 the earth:  admire their lives, and  wish that  when  "J
 the occasion  comes, we may have courage  so  to  :
 die.
   56.  I know but of one solution of the difficulty;  i
 there  must be some element in man which we have  y
 not yet taken account of;  some untiring, undying  fo
 energy which eludes indeed the fingers  and the mi-  a
 croscope of  the  anatomist, but which  exercises a  r
 despotic sway over the  animal mechanism and  takes  {
 possession of it  for its  own use, to the point of ex-  o
 hausting and  finally destroying  it.   Nor is it any  b
 objection to this view, that there may be instances  1
 either  of congenital idiocy or subsequent injury  of   ?
 the brain, where this power is less  manifested; for
 we are not wont to judge of the peculiar characters   i
 of a species from the anomalous exceptions.   The
 power which overmasters and despises sense is yet
 obliged  to convey its  mandates  through bodily or-
gans ;  take these from  it, either wholly or in part,
 and it can no longer manifest  its  existence in the
same way as  when these organs were perfect.  The
paralytic man would move his arm or would express
his wishes if his  arm or his tongue would obey  him;
and his  frequent  impatience at their incapacity suffi-
ciently shows that the  ruling will and the servant 
AND INTELLECTUAL PHILOSOPHY.        79
faculties are of a different  and distinct nature:  nay,
it  has been  observed that even the insane are at
times conscious of and lament a state of brain, which
no longer enables the individual to  act rationally.
This could not occur, were the brain and nerves as
acted upon by external  stimuli, the  only spring of
man's will;  for  then the altered  structure would
invariably  produce  a satisfied acquiescence in  its
results.
   57. It will easily  be seen that if we acknowledge
a  distinct acting principle in the  above  cases, we
cannot  in any other involve  it in  the  accidents of
the body: in  sleep it voluntarily abandons the senses
to the repose  they  need,  and resumes the use of
them when  it  chooses, for who  does not recollect
how, when the weary body required repose, he has
forbidden thought, in order to allow the senses to
fall into the state of torpor necessary to recruit their
vigor?   And there are few, probably, who have not
also  experienced how easily sleep, which would
otherwise have lasted for a much longer period, may
be curtailed by the resolution  to awake at a particu-
lar hour.  In  death,—whatever be  the cause that
exhausts the muscular irritability so far as  to make
it no longer sensible to the usual stimuli, the cessa-
tion of that living action at once stops the machine.
It is in vain  that the musician touches the keys, if
the strings be  broken; but we do  not  thence argue
that the musician has ceased to exist;  nor  have we
more reason to  conclude  that the principle which
claimed the  powers of the living  body for its own
use, has ceased to exist, because the instrument  it
required to  make  its presence  apparent is out of
order or destroyed.
   58. The philosopher, when he sees an effect pro-
duced,  seeks for  the cause: the chemist, if  he  finds 
80      CONNECTION BETWEEN PHYSIOLOGY

two apparently similar substances which under the   flt
same  test exhibit different phenomena, thinks  that   *
a sufficient  cause for considering them different in   af
nature, and  gives them separate names.   If, then,   ;ir
effects occur in  man which are  not sufficiently ac-
counted for by any  known bodily organism or  im-   li
pulse—if under  the same circumstances  he acts as
no other  animal would  act, we  must either on this   K
occasion throw aside all our usual modes of reason-   ^
ing, or we must pronounce that man differs essen-    J'
tially from all other animals, and has a cause of action   5(
not to be sought for  in  nerves and  muscles.   That   i
cause may be invisible; so is the wind: impondera-   »'
ble; so  is electricity: intangible; so is light, if the   'Ji
one organ fitted to receive it be disabled: it is there-    '
fore no new thing  to find an  existing  agency  of    <
potent efficacy which as far as regards our senses is    ti
invisible, imponderable, and intangible.  What we    il
call it, matters not;  it is  evidently  superior to, and    <
master of the body: it has ofher objects  in view,    i
other  pleasures,  other hopes;  and to attain these it
compels its  slave to  undergo  privations, pain, and
death.
  59. I have already referred to  the table where the
phenomena  of  man's  nature  are  reduced to  two
classes: those whose exercise either causes, or is
attended by, bodily change, i. e., emotion, fatigue,
or painful exhaustion—and those, which though in-
cessantly manifested, produce no sense  of weariness
whatever.   It is certainly  among the last  of these
that we must look  for this unknown  and  potent
cause: accordingly we find, that the two unchanging
functions noted in this table are exactly those  which
would give rise  to such actions of the human ani-
mal, as I have described.   These functions or attri-
butes  are, a consciousness of individuality independ- 
AND INTELLECTUAL PHILOSOPHY.       81
ent of the bodily frame, which talks of the limbs
and the faculties as its property, not itself;  and an
intelligent and indomitable will, forming  an essential
attribute of that individual existence.  It is this per-
severing and remembered will, acting frequently in
Opposition to the animal nature, which it is  my ob-
ject  to claim as  the  distinguishing characteristic of
man; as the manifestation of another nature, differing
in attributes from and superior in energy to the mere
bundle of muscles, nerves, and blood-vessels which
we see before us, and which it rules so despotically.
A moment's reflection will show us, that  the memory
inseparable from the exertion of this individual  and
intelligent will, is perfectly distinct from that faculty
of common recollection with which it  may at first
be confounded.   This  latter, like all the other facul-
ties  of  the brain, has  its infancy, its maturity, and
its decline; is strengthened by exercise, impaired by
disease, enfeebled by entire repose; but  the memory
necessary to  individual  consciousness  and  will, is
perfectly insusceptible of fatigue, increase,  or dimi-
nution ; and when palsy or age has taken away the
recollection of persons, of events, and of words even,
the  memory of individuality requisite to the  exertion
 of will remains as strong as ever; and the impatience
 usually attendant on such a state is perhaps one of
 the  strongest proofs, that the organs are  the servants,
 not the cause, of the intelligent will.
   60  We have already seen how far the volition
 which is the result of a shock sent  through  the
 nervous circle can go: it amounts to little more than
 a blind instinct, for the  animals which  possess this
 apparatus  in common with  man, are  incapable of
 education beyond a certain point, and that education
 is onlv to be effected by the fear of pain or  expecta-
 tion of food.  The poverty of language is always a 
 82      CONNECTION BETWEEN PHYSIOLOGY

 great hinderance in philosophical researches, and
 here it is particularly felt; for we have but one word
 to express this instinctive will of the animal and that
 lofty prerogative of man which defies the influence
 of sense, despises the  small globe it inhabits, roams
 over space to find  objects great enough for its con-
 templations; and amid worlds  upon worlds which
 multiply on our  view  as art prolongs  it, still feels
 dissatisfied, and requires nothing  less than  infinity
 for its contemplation—immortality for itself.
   61. If we look through nature,  we shall find that
 the happiness of the organized being  consists in the
 accomplishment of its end of existence.   Animals,
 while supplied with food, and propagating their kind,
 are happy : their span of life is long enough for all
 the enjoyments they require: but man's life is insuf-
 ficient for his wishes, and these gross pleasures dis-
 gust and weary him. Where  is his happiness, then?
 We have seen it!   The captain^f the wrecked ves-
 sel feels his heart  swell with proud  delight as he
 awaits  death with a consciousness of having done
 what, if he were an animal only, would be an act of
 the wildest insanity.  The fair girl,  before whom
 all the pleasures of life were smiling, despises them,
 and  finds her joy in dying with the  object of her
 affections,  because  she feels, even if she  does not
 argue, that thus they will still be united.  The astro-
 nomer has no greater delight  than  to pursue know-
ledge which affords him neither  fame nor  profit;
 though it be only to be gained at the expense of
fatigue at any rate, and probably of health.
   62. These are the pleasures  of a being  whose
nature has other ends than  that of merely spending
seventy years in eating, drinking, and  sleeping, in
the pleasantest way, and leaving other beings so to
eat, drink, sleep, and—die!  Nor is it merely a few 
AND INTELLECTUAL PHILOSOPHY.       83
that thus feel: the consciousness of a higher destiny
is so rooted in man, that even the savage brands him
with disgrace who seeks to preserve life at the ex-
pense of what he may deem honor, and the name of
a coward is the worst of reproaches.   There is
scarcely any cause so slight that man will not  risk
his life for it: can we then with any common show
of reason assert that sensation alone is his source of
action ?  That risk of life brings no pleasure unless
it be a mental one :  he rises in his own esteem by
so doing, and, it may be, in the esteem of others;
but he does so only  because, by despising base life,
he has made good his claim to a higher nature.
   63. We  have asked, what is  man's destination?
I reply  from these  facts—immortality.   We have
asked, what is the ultimate object of his  existence?
I am not here allowed to enter on the higher ground
which would make the chain of reasoning complete;
but if we allow that this rare piece of mechanism is
not created  by the cause that impels it; and no man
has yet succeeded in imitating the smallest  portion
of organized matter; then  a higher intellect must
have produced it, and I can hardly be wrong m as-
suming that the intelligence which planned such a
 scheme  of being, planned it not in vain; and  that
 man is  not the sport of circumstance, filled by his
 very nature with evil desires which it is his business
 to uproot: but that the invisible essence, which we
 Rave found so decidedly manifesting its existence in
 the midst of its bodily trammels, is placed in such a
 situation as to be improved, not deteriorated by, the
 comnanionship.  He cannot alter the  function of
 orfibre of a nerve even; it would be tyranny were
 he called upon  to do so; but he  can  regulate  and
 balance therr  action, and  find those very functions
 which he  can never alter, those very propensities 
84      CONNECTION BETWEEN PHYSIOLOGY

which he  can never subdue, because they are requi-
site to his existence as an animal,—sources of  en-
joyment and of virtue.
  64.  I am forbidden  here* to enter on the nature
of the only other intelligent will which we have any
cognizance of, but this  much  I may be allowed to
say,—that like  natures  must have like enjoyments.
We have  seen  that  all animated nature  seeks  the
end of its  being, and is happy in attaining it: if man
then be akin to that ruling will which both he  and
the  universe own as  Lord, the ultimate object of his
existence must be a like happiness, and we can figure
none to ourselves for such a being but pure  benevo-
lence and perfect knowledge.  Let me here be allowed
to borrow the  words of  a philosophical writer to
whom I am already indebted for many of the views
I have this evening propounded:  I  can hardly give
a better summary of  the practical results  of  the
whole system.  "Thus," says the writer, "we  see
two  kinds of animal functions mutually balancing
each other, uniting to school  the individual will to
all that is  amiable and exalted; the  instinctive emo-
tions softening  the sternness  of  the faculties;  the
faculties curbing the  animal force of the emotions:
and the will, impelled by the solicitations of  the one,
and guided  by  the information and caution of  the
other, acquiring by degrees those habits of  judging
and feeling rightly which qualify man for the spirituaj
felicity of  his Creator.   He has learned the enjoy-
ment  of benevolence and the  excellence of know-
ledge, and his heaven is already begun on this side
the  tomb;  and thus, though these emotions and these
faculties may cease with the bodily mechanism which
  * The rules of the Royal Institution confine the lecturer to
scientific subjects. 
         AND INTELLECTUAL PHILOSOPHY.       85

causes them, they have stamped  their impress on
the individual.  Like metal poured from  a furnace
into a mould, which  retains forever the form so ac-
quired, though the mould be but of earth; the soul
has acquired the character  it will carry with it into
eternity, though the  mould in which it was cast be
returned to its dust."—Philosophical Theories and
Experience, p. 74.
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