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                      RESEARCHES

                             INTO THE


COMPARATIVE  STRUCTURE   OF  THE  LIVER,

                    BY JOSEPH  LEIDY, M. D.

                         WITH THREE PLATES.

   [Extracted from the American Journal of the Medical Sciences Tor January, IMV;
  The following observations* on the comparative structure of the liver were
made solely for my own satisfaction, but I have been induced to make them
public from the impression that some of the facts presented may be new, or
that, at least, the anatomy of the liver being presented in a somewhat new
aspect, may be better understood than by former methods of description.
  It will be remarked  that as respects the anatomy of the  liver of verte-
brated  animals, the  facts  observed by me corroborate the  very carefully
made researches and accurate  descriptions  of the anatomy of the human
liver by Mr. Kiernan. {Philosophical Transactions, London,  lsW.)
  The constant presence of the liver throughout the whole of the vertebrate
scries of animal life and  the higher orders of the invertebrate series, is
sufficient proof of the  importance of the organ, in connection with the
digestive apparatus.  It is an extensive secreting surface collected into a
small bulk, and in the vertebrata it is arranged in such a complex manner,
that before the researches of Mr.  Kiernan, anatomists entirely failed in
obtaining any satisfactory knowledge relative to its arrangement.
  Before entering upon the details of the anatomy of the liver, it may be
well to examine in a very general  manner the nature of secretion and the
orcans which possess this function.   It is  rather difficult  to give a good
general deliniiion of the term secretion, for there  are many organic pro-

  .  These observations were made with an excellent microscope manufactured by
Oberhaeuser. ,1  I»ar». and belonging .o  Dr. Wm. Schmode.of lb.,  c.y. 10 whose
liberality 1 am indebted for its use during a long period. 
2         Leidy on the Comparative  Structure of the Liver.
 cesses which closely resemble it; such are respiration,* the renewal of epi-
 thelial surfaces, growth  of hair, &c.;  but to  restrict it in some  degree, it
 may be considered to be that process in an organic being by which certain
 organic cells, forming part  of  its composition, separate or form from  the
 nutritive fluid, in contact with them upon one side through the intervention
 of a basement membrane, certain peculiar substances, which they give up
 upon the  other side,  to be  appropriated to  some  other purpose in  the
 organism, or to be cast ofTas useless, or which  would be hurtful if retained.
   Particular organs devoted to this function are denominated glands, and
 the simplest form of a glandular  body is a single organic cell resting upon
 a basement membrane, and having the function just spoken of.   Such  are
 probably the cells  which secrete the irritating  fluid in the Medusas, certain
 cellules in the Po/ygnstric animalculae, $c.  An increase of such cells upon
 a plane surface is  a little advance on the  former state, and appears almost
 as simple;—of this character are the glandular patches  found in the ali-
 mentary canal of insects, &c.  The surface  upon which the secreting cells
 are placed,  being depressed below the general level, adds a little more to
 the complexity of the structure, and in this way the simple mucous follicles
 are formed,—the follicles of  the provenlriculus of birds, follicles of Lieber-
 kuhn,&c.   Should these depressions, which if deep are tubular, be divided
 towards the  extremity, it increases the amount of secreting surface, and
 renders it more  complex,—as in  the compound follicles of the  stomach,
 the sebaceous follicles of the skin, &c.  If the divisions be subdivided,
 glands like the salivary, lachrymal, &c, are formed.  If, instead  of subdi-
 vision, the primitive divisions are much elongated, and convoluted  to econo-
 mize space, we have a gland of which the testicle of the higher vertebrata
 is an example.   If  the tube be divided and subdivided to a great  extent,
and each ultimate  division forms a reticulated  mass  of tubular  structure,
the most  complex  form of a gland is produced, as in the fully developed
liver of most vertebrated animals.  The  relation  of the channels which
convey the  nutritive fluid to and  from  glandular  organs, of course  adds
cons.derably to their  complexity.   From  the  foregoing we perceive the
complexity of a gland depends upon the extent and  mode of arrangement
of its secreting surface and the relation of the  blood-vessels to it.
  The quantity of secreted matter depends upon the number and activity
of the  organic cells forming a secreting surface, and the quality appears
not to depend upon the complexity of the gland, but upon the power of the
individual cells ;  for the same secretion produced in glands of the most  in-
tricate arnngement in higher animals, is produced in very simple structures
in  the lower animals, as instanced in the liver of the higher vertebrata, and
that ofJimphioxus lanceolutus, the testicle of  man  and that oUulus,  &c.
  • In respiration there is not only a substance derived from .he blood and given off
externally, but a.so one derived from the exterior and  given up to «he blood lo thai
there ,s an interchange of substances which is not .he case in secretion 
Leidy on the Comparatirr Structure of the Liver.         3
  In the lowest forms of vertebrated animal life, where no distinct digestive
apparatus exists, we find no trace  of biliary structure.   When we rise  a
little in the  scale, and arrive at animals with an internal digestive cavity, as
the Polypi, it is probable that certain of the cells forming part of the parietes
of the cavity, may  possess the power of secreting a fluid analogous to bile.
< 'ertain cellules, also, of the Polygastrica  may be devoied to this purpose.
The few short cu-ca of the digestive cavity of many Medusx may also be
 biliary in their nature.
   In the Txnoidea and Tremafoda, animals which have a ramiform digesi-
 ive apparatus, the coecal appendages have been considered as a rudimentary
 form  of the organ.  They, however, do  not differ in structure, which  is
 granular, from the main portion of  the cavity, and, like the latter, receive
 part of the alimentary matter.  The ctecal  appendages  of the digestive
 cavity of ihe Echinodermata are reported as representing the biliary struc-
 ture,  a question, as in several of  the former instances, which I have  not
 yet examined.  In many Annelida there are casca appended to the sides of
 the alimentary canal,  which are lined by organic cells of small size, and
 probably  secrete  a biliary fluid,  as in  Hirudo,  Arenicoia, &c.   In  the
 Mi/riapoda, emptying into the intestine, there are several long and delicate
 tubes of basement membrane lined  by  secreting cellules, in the Julidx
 averaging  012.1 millimetre in diameter, which are no doubt of this nature ;
 but as they do not differ in structure from corresponding tubes of insects, a
 more particular description of the  latter will answer for the former.
    fleets  —In insects the liver consists of a number of dstinct, white, yel-
  low or brown, filiform, tortuous tubes placed in close  apposition with the
 sides of the  alimentary  canal  and opening into  it, generally hy separate
 orifices, frequently afier joining  each other to form short trunks, as in
  Musca, Tabunus, &c,  in  the vicinity  of  the pyloric  extremtty of the
  stomach.  The smallest number, which is four, occurs in the fl.es (Ihptera);
  in the Lepidoptera there are  s,x ;  and in the Orlhoptera and Hymenoptera
  they are numerous.   When  few  in number, they are very lot!,, somet.mes
  three or four tunes the length of the intestinal canal; when numerous the>
  are  proportionately short, and more delicate.  In some  ms-cis they termi-
  nate in blind extremities, as in many Diplera, in others they unite ,n pa.rs
   t their farthest extremtty.so as to form loops as in the b^»-<0
     When  more intimately examined, these tubes (Plate I. F.g>. -. J,  I. 5
  0) a^  found to consist of a delicate tube of clear, transparent, amorphous
  bLement membmne, the inner surface  of which is covered wnh secreting
  r I   Fr -The thinness of the tube, the cells often  project so as to g,re
      Granulated appearance  when  viewed by the nake  ey,  «  ■« «£«
  fly, (.,/,„„, carnaria.) ,l»l. 1. Fig. 10 and generaHy "™* ** f« "
  tremitv, the  sides of the tubes are so irregular that they appear as ,f mere.y
   foMfd.po- <he  secre^ngcelU to k,eP them ^    ^ ^ ^
     The accreting cells (I l. l. * 'Bs-  *•  '  ' 
4          Leidy on the (omparalive Structure of the Liver.

cylindrical from elongation.   Their average measurement is about -09 mil-
limetre.   The contents are white, yellowish, or brownish, and consist of n
finely granular matter, numerous fine oil-globules, a granular nucleus, and
a transparent nucleolus.
  The cells in the extremity of  the tubes are  not more than half the size
of those, a little farther on, or nearer the termination, and contain less gra-
nular matter, and no  oil-globules, so that they are more distinct, and the
nucleus more apparent.  Upon advancing a very little, the cells are found
to be of an increased size and full of granular matter, so as considerably to
obscure the nucleus from  view.   A little farther, we  find  the  addition of
fine oil globules readily distinguishable by their  thick black outline, when
viewed in a certain focus.   Sometimes the  cells become  so filled with oil
as to be distended with it,  rendering the granular matter and  nucleus  so
transparent, as totally to destroy all appearance  of the former, and the latter
only is to be perceived in  faint outline.  Such a state I have frequently
observed in Dermestes, Jlteuchus, &c.
  The nucleus (PI. I. Fig.  7) is generally central, globular,  and pretty
uniform in size in the same species, averaging in measurement about -025
millimetre.  Sometimes;, as in Cicada, &c, where the cells are elongated,
the  nucleus is also irregularly so.  (PI.  I. Fig. 5.)
  The nucleolus is always transparent, and  measures  about -00G of a mil-
limetre.
  The central passage of the tubes, or separation of the cells in the middle
line, is usually found  filled with fine granules and a  great amount of oil
globules.   (PI. I. Figs.  1, 5.)
  The biliary tubes of insects are bathed  in  blood or the nutritive fluid,
and the  respiratory tracheal  are distributed to them with extreme minute-
ness, but are separated from  the  secreting cells through the intervention of
the basement membrane.  (PI. 1. Figs. 2,'.}.)
  Crustacea —The liver in  the common cray-fish (JJstacus ajffinis) of our
rivulets, consists of two large lobes, one on each side of the intestine, united
by an isthmus anterior to the middle.  Each lobe consists of numerous long
conical  coeca, aggregated  together.  (PI. I. Fig. 8.)   From each ccecum
passes off a narrow duct,  to  join a common trunk which  opens into the
intestinal canal, in  the  vicinity  of the  pylorus.  In  structure the  cceca
(PI. II. Fig. 9) resemble the tubes of insects, being composed of a sac of
basement membrane,  within which, originating from the inner surface, are
numerous secreting cells.  The cells are  more or less polygonal in form
from mutual pressure.  In  the  bottom of the  coeca, the  cells (PI. II. Fig.
10) are small, with an average diameter of -02  millimetre, and contain a
finely granular matter of a yellowish hue, with  a granular nucleus, and a
transparent nucleolus.  As we proceed  from the bottom onwards, the cells
(PI. II. Figs.  11, 12,  13)  are found to  increase in size, and  to obtain a
gradual addition of oil globules, until beyond the middle of the  tube  where 
Leidy on the Comparative  Structure of the Liver.        &
they are found filled with oil, so as to have  the appearance of ordinary fat
cells, and have a diameter averaging '00 millimetre.  From this arrange-
ment of the cells, when a  ccecum is viewed beneath the microscope, (PI.
II. Fig. M,) its lower half  appears filled wilh a finely granular matter in-
termingled with  nucleolated nucleated bodies, and the anterior half, with a
mass of fat cells, the nucleus hardly visible, from  the property of oil ren-
dering organic tissues  more or less transparent.  The central cavity of the
cu;ca is filled with fat globules, and a finely granular matter  corresponding
to that in the interior of the cells.
   Molhisra.—The liver of  the slug(Limax) and snail (Helix) consists of
 five lobes which are subdivided into lobules, (PI. I. Fig. 10,) and each lobule
 is composed of numerous bulbiform cteca, polygonal from mutual pressun*.
 From  each of these passes off a duct, which by union  form two trunks
 opening into the duodenum.
   When  one of the bulbiform coeca (PI. I. Fig.  10) is examined beneath
 the microscope, it  is found to have a structure differing in no important
 particulars from that  of the cray-fish.  The cells (PI. II. Fig. 17; at the
 bottom of the sac average -02 millimetre in diameter; those towards the
 other  extremity about .01 millimetre.  Some of the fully ripe cells  (Fig.
  is) are filled with innumerable minute  globules of oil hardly distinguish-
 able from the granular matter ;  others (Fig. 10, «, b, c) with globules of a
 larger size;  some  (Fig. 21) are  found with from one to ten, or more,  large.
 deep  yellow oil globules in the centre; a few (Fig. 22) wuh ■  h"^"
 cryTtall.zed mass of fat in  the centre ; and many (Fig. 20) are distended
  with  oil.   By Pressing the cells (Fig. 2:1) between two plates of glass, the
  coments  will be squeezed out, and the structure will be seen as W»°«r.:--
  The  vesicular, transparent, amorphous cell wall, finely granular matter, fa
  globules, and a granular  nucleus, measuring about -01 millimetre and
  containing a hard, transparent  nucleolus.  A few of the cells contain two

  ""The blood-vessels, consisting of arteries and veins, form  a rete around
  the bulbiform „«. but do not  appear to come in  -™^^^
  ,, secreting cells.   <^£™^^^£ '^T^
  them numerous  nucleated fa  ceIs x^ and     ^            ^ ^

  ^n-co^ed"-;;;"::-  *-  ,.:«..*—«*»»

  ^^zzr:£z p:z: *, ^, of „T *. and „  z
     I ertebrala.  in                                hssures ]nl0 seyeral
  general  regular form.  I  i.  u.u.Uy        ^M  In colour ,t p,>sea
  portions or lobes,  which  are invest, u \                         bn.w.ii.u

  purPle.  and bro»n.   U  -n  he•                   ^ ,w ,ppBmB8, 
6         Leidy on the Comparative Structure of the Liver.

colour.   In  intimate structure it consists of numerous,  small, irregular
bodies, or lobules (lobules of Kiernan), corresponding to the lighter por-
tions  just mentioned, which  are lobulated  themselves and  closely con-
nected  together  by means  of white and yellow fibrous  tissue and  the
blood-vessels belonging to the  organ, which correspond to the  dark ground
lines  separating the lighter-coloured  masses.  The  lobules are not regu-
larly arranged side  by side  throughout the liver, but  lie in all directions,
principally,  however,  with  their long  diameters at right angles to the
surfaces.  When the vessels of a liver have been injected, and the organ
then  hardened in alcohol so that  it may be rendered more consistent and
its difference of structure more perceptible, and  a section  made at right
angles to the surfaces of the  organ, a view like  Fig. 31, PI. 111., will be
obtained.   In such  a section  lobules will be observed to  be cut  in  all
directions;  longitudinally, when  they have  a  foliated appearance;  ob-
liquely  or  transversely when  they have  a more  or less  polygonal  form
depending upon the amount of mutual pressure at any part  of the liver,
being greatest in ihe interior, least  near the surface.  In  their interior,
sections of blood-vessels are seen, which belong to the hepatic veins ; and
the vessels occupying the interspaces between them are branches of the
hepatic  artery and vena portarum.  The lobules are  composed of an inter-
texture  of biliary tubes, (pori biliari,) (PI. 111. Fig. 32,) and  in  the areola? or
interspaces of the network the  blood-vessels ramify and  form amongst them-
selves an intricate  anastomosis, the whole  being intimately connected to-
gether by a  combination of the white fibrous and yellow elastic tissue.
   In  structure the biliary tubes (PI. II. Figs. 25, 28; PI. Ill Figs. 33, 34),
correspond with those of the invertebraia, consisting of cylinders of base-
ment membrane containing numerous secreting cells, and the only difference
exists in the arrangement; the free tubes  of  the lower animals in the ver-
tebrata  becoming anastomosed  or  forming an inlertexture.  The tubuli vary
in size  in an unimportant degree  in different  animals, and also in the same
animal, being generally from  two \o two  and a half times  the diameter of
the secreting cells.   The tubes of one lobule are distinct from those of the
 neighbouring lobuli, or only communicate indirectly by means  of the trunks
or  hepatic ducts originating from the tubes and lying in the interspaces of
 the  lobuli.   The secreting cells (PI.  II. Figs. 25, 20, 27, 20, 30 ; PI. III.
 Figs. 35,30,37) are irregularly angular, or polygonal in form from mutual
 pressure, and line the interior surface of the tubes.   They vary in size  in
 a moderate  degree  in different animals and also in the same animal, appear-
 ing to depend upon certain conditions of the animal and liver.  The colour
 is light yellowish, or brownish when in mass, the other and darker colours
 of the liver appearing to depend  upon the blood in the organ.  They con-
 lain a'finely granular matter, oil globules, a granular nucleus, and a trans-
 parent  nucleolus.
   The finely granular matter is  the  portion from which the colour  of the 
 
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           Leidy on the  Comparative Structure of the Liver.         7

cell  is derived ;  it appears  to  be made up of innumerable  exceedingly
minute spheriform granules, which, when under a  low power of the micro-
scope and  well defined, look like  so many minute black points.  This sub-
stance, from its  quantity and minute state of division, often obscures the
nucleus so that it cannot  be distinguished until  acetic acid is applied to it,
when  it is rendered more translucent without affecting the nucleus.  The
oil  globules vary  in  quantity in different conditions  of the  liver, and in
different cells.   It exists in  the form of exceedingly minute globules, look-
ing like so many intensely black points, and hardly perceptible  from the
granular content.-) of the cells, up to larger and distinct globules, sometimes
one-fourth  the diameter of  the cell.   From this gradual advance from the
state in which it is hardly distinguishable from  the granular matter up to
a large size, and in the invertebrata even to a distended slate of the cell, a
gentleman, to whom  I presented the observation, supposed that the liver
 only secreted  fatty matter, while the gall-bladder secreted cholesterine, the
 latter fact being presented to his observation in  several pathological cases,
 in  which the cystic duct was  obstructed and the  bladder filled with white
 concretions (biliary calculi), which consisted of pure cholesterine.   This,
 which appears  plausible at first view, falls at once to the ground  when it
 is  recollected that some  animals have no gall-bladder, as the horse-, sloth,
 &c, and yet  secrete a bile constituted  like that  of animals possessing a
 gall bladder.  The giraffe, it is also well known, in the three or four cases
 in which  the  animal has been dissected, in two cases had no gallbladder,
 and in a third instance possessed one of large size.   1 have mentioned that
 the quantity of  oil globules varies in  different conditions of  the animal or
 organ.  If the animal be very fat, or be well fed, especially on substances
 containing much starch, it will be found in greater abundance than usual;
 as  may be readily seen  in the difference between  poultry which run about
 and those  which are penned up  for fattening;  and I have no doubt that in
 the preparation of the liver of  geese, in which it becomes enormously en-
 larged, for making the. "pate defoie gras de Strasbourg," there is not the
 addition of a single secreting cell, but merely an  accumulation of  fat glob-
 ules, within  the secreting cellules,  derived  indirectly  from the starchy
 matters of the food, which ordinarily are consumed in the process of respi-
 ration.   In  phthisis, in which  more  or less of the  respiratory surface is
 destroyed, the  liver appears to  take  upon itself  part of the office of the
 lu..<rs.'but rids the blood  of  the excess of carbon in another way, that is
 bv converiino- it, with the elements of water, into fat, which >s deposited
 within the cells, producing what is called "fat liver/'  The same condmoa
 of the  liver is  produced  in  drunkards, probably from the sumu at.on to
 nutrilion and the conversion of the alcoholic constituents mto lat.  It u also
 produced in some other ways  not well understood, as was Panted to ™
 Llv in a case  of  Prof. S. Jackson's, in which the  patient had  laboured
 for a long time  under disease of the liver and dy.pcp.ia. and died of hemor- 
8          Leidy on the  Comparative Structure of the Liver.

rhage from the bowels consequent  on extensive  ulceration of the mucous
membrane.
  The nucleus is generally central, frequently lateral, globular, and pretty
uniform in  size in the same animal.  It is granular in structure and never
contains oil globules ; generally, it is  but indistinctly seen, excepting in
fishes and reptiles, and frequently  not at  all, from the granular contents of
the cell obscuring it, but is readily brought into view by the influence of
acetic acid  upon  the hitter.   Sometimes there are two nuclei instead of one.
  The nucleolus measures  about  -001 millimetre, is  round in form, con-
sistent, and transparent, and is situated in the centre of the nucleus.
  The interlobular trunks or commencement of the hepatic ducts, as they
originate from the biliary tubes or pores, run in varied directions in regard
to the  lobules, and  freely anastomose with each other, and  by their  con-
vergence form trunks which take a general course at right angles to the sur-
faces of the liver, and finally appear by several  trunks externally beneath
the liver.
  The blood-vessels (PI. III. Figs. 38,39) of the liver consist of two sets, the
hepatic artery and vena portarum, wrhich convey  the blood  to it, and a third
set, the hepatic  veins, which  conducts the  effete  blood  from  it into the
general circulation again.
  The hepatic artery, much smaller than the vena portarum, appears to
be appropriated to the nutrition and supply of oxygen to the tissues enter-
ing into the composition of the liver;  while the  vena portarum is probably
devoted to  the conveyance of  blood  to the  secreting cells, which appro-
priate  the  peculiar  fluid of the liver, or bile  from it.   These two vessels
enter  the liver at the  place of exit  of the  hepatic  ducts, and follow the
same  course  inwards that the  latter  did in coming out.   The artery in its
passage supplies the ducts with branches and the vena portarum with vasa
vasorum.   In the  intervals  of the lobules they comport themselves  very
much in the  manner of the interlobular ducts, and  form  an intricate  net-
work around  the lobules, but whether the two sets of vessels anastomose I
could  not satisfactorily determine.  They  both send off numerous branches
which  enter the  lobules at right angles to the length of the latter,  and  form
an intricate plexus by turning  through the interspaces of the biliary tubes.
The vessels within  the  lobules  freely communicate with each  other  and
converge towards their interior, where they  terminate  in  trunks, which
run in ihe  length of the  lobules, and  are the commencement of the hepatic
veins.   This  free intercommunication of  the  three sets of vessels within
the lobules has been fairly proved  to me by a minute  injection of a young
liver,  by Prof. Wm.  E. Horner, of the University.  All three of the  ves-
sels have been injected with red size, and it has  penetrated beautifully, and
a fine section from almost any part of  it, beneath the microscope, has the
appearance represented  in Fig. 39.
   The commencing branches of the hepatic veins  issue from the base of 
 
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Leidy on the Comparative Structure of the Liver.          9
the lobules, and by their convergence, form several large trunks, which pass
out of the liver at right angles to the other two sets and parallel to its sur-
faces, at its dorsal margin close to the spinal column.

    Measurement of the Secreting Cells of the Liver of some Animals.
 (Vntiped (Julus impressus) cell, .0125.
 Tumble bug (Jtevchvs volt-ens)  cell, longest diameter .0225 in.;  shortct. 0125 m.
 Katydid (Pliilyphyllum roncuvum) cell, .13 m. in length; nucleus .0225 m.
 He„i--lly (Musca domestica) colls, .<•'.) by .00 in.; nucleus .0225 m.
 I'le-h-fly (   "   cartiaria) cell, .09 m.; nucleus .0275 in.; nucleolus .000 m.
 Cray fi~ 11  (Jstants qffmis) cell, .02 to .00 in.; nucleus .015 in.
 Snail {llcltx albolabris) < ell, .02 to  .04 in.
 Ship; (Limax varitgatia) cell, .03 to .00 m.
 Hod; fish (Labrax tinnitus) cell, .0275 in.
 Minnow  (Hydrargira ornuta)  cell, length .02 m.; breadth .015 in.
 Cat-fish  (Pimelmlus catus) cell, .0275 in.
 Liznrel {Triton niger) cell, .03 m.; nucleus .0125 m.
  Frog (Rana hakcina) cell, length  .03 m.; breadth .02 m.; nucleus .005 to .01  ra.
  Terrapin (Entys terrapin) cell, .03 m.
  Snake (Tropiilonotiet sirtulis) cell, .02 to .0275 m.
  lion {Boa constrictor) cell, .03  m.;  nucleus, .0150 in.
  Du.k (Jnas acuta) cell, .0175 to .02 m.; nucleus .000 m.^
  Owl (Strix brachyotos) cell, average .015 in.; nucleus .005.
  Chicken {Callus domtsticus), lean, cell .010 in.; fat, .017 m.
  Ground Squirrel (Saurus striatus) cell, .0175 in.
  Gray     "    {Sciurus  Curolinensit) cell, .015 m.
  Babbit (Lepus Jtnericanm) cell, largest .03 m.; smallest .015 m.; nucleus .01 m.
  Sloth (liriulypus tridactylus) cell, .0133 in., remarkably diAncL
  Leopard {Felts leopardis) cell, .0125 to .015 m.
  Monkey {Stmia-------0 (American) cell, .015 m.
  ManJ-ell, largest .03 by .02 in.; smallest .015 m.; average .02 m., nucleus .00     ,
           nucleolus .001 in.

                     Explanation of Plates  /., II. and III.

   ri,.  r^.....—«-......^.zrz^z:^^'
            the flesh fly {Musca  carnana), viewed  by renecieu iigm,



     .. 3, From .he how. ely; eihihietag ehe »..» « '«■ '-'■ »■"' "» ""'"""
            out form of ihe cells.                         .„_m,;fi«l  The  secreting
     u 4. Portion of a biliary lube from the house fly. highly "^ J_  whWl
                    ,en ranged  upon each Mile with a pa>*ag<  bet« " n
Is nre
    is tilled with oil globule*.               fPlaluvhullt.m eontacum), exhibiting
5, 6, Portion, of a biliary tube from the katydid (Platyphyllt
   ',he elongated cells and nuclei.                          magnified.  The





 '   exhibiting the structure of c«eal tubes. 
10         Leidy on the Comparative Structure of the Liver.

Fig. 9, A  ccecum or biliary tube of the  cray fish (from  an individual which was one
         inch in length and had  been well fed  for some time), highly magnified.  At
         the bottom is seen a confused mass of cells with their nuclei and nucleoli, but
         at the upper part of the sac they are seen distinct, and polygonal from pressure.
         and filled with oil which renders them transparent.  At the mouth or open
         extremity numerous  detached cells and oil globules are perceived, which have
         been squeezed out by the pressure of a thin plate of glass.
Figs. 10, 11, 12,  13, a, b,  Exhibit the progressive change of the cells as they advance
         from the bottom of the tube.
Fig. 14, Nuclei, from the secreting cells of the liver of the cray fish, highly  magnified.
 "  15, Portion of the  liver of the snail  (Helix albolabris), moderately magnified, exhi-
         biting the arrangement of the lobules.
 "  16, A biliary ccecum  from  the liver of the  snail, highly magnified.  It  shows the
         same structure as fig. 9.
 "  17, a,  b, Two cells, from the bottom of a biliary ccecum of the snail, highly magnified.
 "  18, a,  b, Two cells, more advanced, containing numerous very minute oil globules.
 "  19, a,  b, c, Three cells, containing larger oil globules.
 "  20, A cell distended with  oil.
 "  21, A cell containing nothing but six deep yellow consistent oil globules.
 "  22, A cell containing a hard yellow mass of fat.
 "  23, A cell ruptured and its contents escaping.
 "  24, Nuclei, from the cells  of the liver of the snail, highly magnified.
 "  25, Portion of a biliary tube and secreting cells, from the liver of a lizard  (Triton
         niger), highly magnified.
 "  26, Secreting cells, from the liver of an owl  (Strix brachyotos), highly magnified.
 "27,    "       "  from a duck (Anas acuta).
 "  28, Portion of a biliary tube of the rabbit (Lepus Americana*), highly magnified.
 "  29, 30,  Secreting cells from the liver of the rabbit.
 "  31, Longitudinal section of  human liver from the posterior part near the upper sur-
         face, magnified  3  diameters, from a preparation made by Prof. W. E. Horner
         of the University  of Pennsylvania.   The  three  sets of blood-vessels were in-
         jected  with colouring matter and the  preparation then preserved  in  alcohol.
          The blood-vessels represented in the  drawing belong to the hepatic veins, and
          are seen at various parts coming from  the interior of the lobules.   The spaces
          between the  lobules, which are filled with branches of the  hepatic artery and
          vena portarum and  hepatic ducts, have been purposely left white so as not to
          obscure the view of the  lobules.
 u 32, Transverse section of a lobule of the human liver, taken  from the same prepa-
          ration  as  fig. 31, highly magnified, and presenting to view the retietulated struc-
          ture of the biliary tubes.  In the  centre of the  figure is seen the hepatic vein
          cut across and several small branches  terminating in it.   Where the injecting
          matter did not run freely, it is seen  standing  in dots along the  course of the
          vessels.  At the periphery are seen branches of the hepatic artery,  vena porta-
          rum and  hepatic duct.
 " 33, A small portion of fig. 33 more highly magnified.  The secreting cells are seen
          within the tubes, and in the interspaces of the latter the fibrous tissue is repre-
          sented.
  " 34, Portion  of a biliary  tube, from a  fresh human liver, very highly magnified.  The
          secreting cells may  be noticed to be polygonal from mutual  pressure.
  B 35, Three secreting cells detached.
    30, A secreting cell much more highly magnified, representing plainly the internal 
Leidy  on the Comparative  Structure  of the Liver.          11
         structure.  The granular nucleus  is central, and the imall Uxlics with thick
         block outlines represent oil globules.
Fig. 37, Four seireting cells, from a human liver, in a diseased  condition calW  "fctty
         degeneration" or ''fat liver."  The ^reut increase of oil globules is ob*crv»ble.
 "  38, Transverse section of a lobule, from the tnmc preparation b« 31 and 32, but not
         so highly magnified as 32, representing the relation of th,' three k< ts of blood-
         vessels with each  other and with  the biliary tubes.  The anery is coloured red,
         the vein blue, and the vena portarum yellow.
  "  39 U<  presents a longitudinal section, highly magnified, of a portion of n lobule, from
          an injected  preparation, made by Dr. Horner, of the  liver of a chiM about 6
          years of age.   It  will bo perceived there  is a free anastomosis of th*> three
          gets of  vessels, which have  all been successfully injected with re-d colour,i,g
          matter.  Spaces arc also observablo through which the injection failed to p*»«. 
 
Observations on Ike existence of the Intermaxillary Bone in //<■  Embryo of the
                               human subject.

                          By  Joseph Lbidt, M. D.

  The immortal Goethe, I believe, was the first to point out the existence of th,
08 iiiteruiaxillare  in  the human subject, but it  has  only been  observed  in  an
abnormal condition, or where  there has been an arrest of development in con-
nection with some cases of hare-lip; and the period  of life in which it is found
as a distinct piece, and its exact limits, have not  yet been accurately determined.
 The' universality of the presence of the os intermaxillare in all  animals  l„ 1 ,\v
man, its presence as a distinct piece  in an abnormal condition  in man, always
defined by a lateral fissure which characterizes  it  as the incisive bone, and  the
uniform existence of a transverse fissure behind the incisive alveoli of  the os
maxillare  supcrius of the human ftetus at  birth,  have  led  many anatomists to
suspect its normal and independent existence in  the embryotic condition of man
at an earlier period than it has been sought for.
   As  the  negro  in his aaatomical characters is  not so far removed from  the
embryological condition as theW«'*e,it is to be presumed that the intermaxillary
bone would remain longer distinct; and under such an impression 1 have several
times desired medical students, from our Southern  States, whose opportunities ol
 investigating the anatomy of  the negro are frequent, to make  this a subject oft
 inquiry.  Such an opinion cannot be considered unworthy of attention, when it
 is recollected that Tschudi  mentions the existence of a true os  interi»rictah', as
 a constant condition, in certain branches of the  aboriginal inhabitants of Peru,
 the Chinchas, Aymaras and Huancas.
   Recently having had an opportunity of examining  several  human enltyos in
 one of them  I was fortunate  enough to  detect  the intermaxillary bone aa a dis-
 tinct and independent piece.  This  embryo  measured  one  inch  and  eleven
 lines from heel to vertex, and I presumed it to  be about nine or ten weeks old.
 In  it ossification had already advanced in the  superior  maxillary  and inter-
 maxillary bones  sufficiently to give them a determinate form, and their  appear-
 ance, when magnified, is represented  in the figures land 2, which were takeo
 from the specimens through the aid of the camera lucida.
Fig. 1,
Fig. 2.
b—
 
    Fig. 1 represents the superior maxillary and intermaxillary bones, much mag-
 nified,' of a human embryo.   The diawing was taken from the right side through
 the aid of the camera lucida, which reverses its position,  a.  superior maxillary
 bone;  A. intermaxillary bone;  c. line of articulation between  the two bonesj
 d. palatine process;  e. alveolar groove.
   Fig. 2 represents the antero-inferior surface  of  the  separated  intermaxillary
 bone, much magnified.  (From the left side, but reversed by the camera.) a. ascend-
 ing or nasal process;  6. articulating surface tor the superior  maxillary bone j
 c. incisor alveoli.

   The greatest breadth of the two bones in apposition is one line and two-thirds.
 the greatest height, being at the ascending or nasal process,  is one  line.  The
 two pieces present a facial  portion, consisting of the ascending  or nasal process
 and part of the body  of the bones; an  alveolar ridge and groove  and a palatine
 process projecting backward from the superior maxillary bone.  They are easily
 separable at this period, and the articulation passes through the alveolar ridge at
 a point corresponding to the separation  between the incisor alveoli  and the canine
 alveolus, and extends transversely inwards behind the incisor  alveoli, and verti-
 cally upwards, dividing the nasal process  into  two  nearly equal  portions.  On
 the  posterior surface of the nasal process the articulation is at  the  bottom of a
 comparatively deep and wide groove, which, however, does not appear to be part
 of the lachrymal canal, as the latter appears afterwards and external to the former
 groove.   The preparations exhibiting these  interesting  points which prove the
 existence of the same law, throughout the animal kingdom, governing the forma-
 tion of the upper maxillary bones, I present for the inspection of the members of
 the  Academy.
   In an embryonic skeleton in the Wistar Museum, measuring three and one-
 eighth inches in length,  and purporting to be about  nine weeks old,  which,
 however,  I think  too  young, the  maxillo-intermaxillary articulation is  still
 evident at the ascending process, but it does not divide  the latter so equally,
 being more internal and inferior, apparently from a  more rapid  development of
 the nasal process of the  true maxillary bone.  Just above the alveolar ridge they
 are already anchylosed together.
   In another  embryo,  in the same museum, measuring three  and  one-fourth
 inches in length, the two bones have become firmly united, excepting behind the
 incisor alveoli-, but  the  line of original separation is readily traced out, from a
 greater degree of thinness and transparency along its course."  The  nasal process
 of the true maxillary bone has so much increased beyond the nasal process of the
 intermaxillary bone, that the latter no more ascends to the summit of the former,
 but is considerably inferior and internal.
  In the fetal skeleton, measuring five inches in length, all traces  of the inter-
articalation h*ve disappeared, except  behind the incisor alveoli,  which latter
portion, as is well known, does not usually disappear  until some time after birth,
and in some instances  is found in the adult cranium. 
 
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