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MICROSCOPIC AN ATOM i

THE HUMAN BODY,

HEALTH AND DISEASE.

ILLUSTEATED WITH UPWARDS OF 400 DRAWINGS IN COLOUR.

BY

ARTHUR HILL HASSALL M,D, LOND,

^AUTHOR OF

A "HISTORY OF THE BRITISH FRESHWATER ALG^;"
LICENTIATE OF THE ROYAL COLLEGE OF PHYSICIANS OF LONDON ;

FELLOW OF THE LINN-dEAN SOCIETY ;

MEMBER OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND ;
ONE OF THE COUNCIL OF THE EPIDEMIOLOGICAL SOCIETY,

ALSO OF THE BOTANICAL SOCIETY OF LONDON;

CORRESPONDING MEMBER OF THE DUBLIN NATURAL HISTORY SOCIETY
PHYSICIAN TO THE UNITED KINGDOM LIFE ASSURANCE

COMPANY. >

IN TWO VOLUMES.

VOL. I.

LONDON:
TAYLOR, WALTON, AND MABERLY,

UPPER GOWER STREET ; A1JD IVY LANE, PATERNOSTER ROW.

852. MICROFTLM!:D '
UNIY

imm

MASTER' Nl

LONDON :

SPOTTISWOOOES and SHAW,
New-street- Square.

THE

MICROSCOPIC ANATOMY

OF

THE HUMAN BODY,

PAKT I. THE FLUIDS.

THE constituents which enter into the formation of the body,
and by the combination of which the human frame is built
up, naturally resolve themselves into two orders, FLUIDS
and SOLIDS, the latter proceeding from the former.

In accordance with this natural division of the elements
which enter into the composition of the body, it is in-
tended to divide this work into two parts, the first of which
will treat of those components of our framework which are
first formed — the FLUIDS ; and the second will be devoted
to the consideration of those constituents which proceed from
the fluid elements, viz. the SOLIDS.

Of the fluids themselves, it is difficult to determine upon
any subdivision which shall be altogether without objection,
perhaps the most practicable and useful division of them
which can be made is, into ORGANISED and UNORGANISED.

To the above arrangement of the fluids the following
exception might be taken : all the fluids in the animal
economy, it may be said, are to be considered as organised,
inasmuch as their elaboration is invariably the result of
organisation. But it is intended that the words organised
and unorganised, when applied to the fluids in this work,
should have a very different, as well as a more precise signi-

B

2 THE FLUIDS.

fication, and that those fluids only should be called organised
which contain in them, as essential, or at all events as con-
stant constituents, certain solid and organised particles, while
those liquids which are compounded of no such solid matters,
as essential portions of them, should be termed unorganised.

In the first category, the lymph, chyle, blood, mucus, as
normal, and pus, as an abnormal fluid, would find their places
together with the milk and semen. The fluids of this class,
it will be seen, belong especially to nutrition and reproduc-
tion, and admit also, naturally, of arrangement into two
series ; in the first, those fluids which are concerned in the
nutrition and growth of the species itself would be comprised,
as lymph, chyle, and blood ; and in the second, those liquids
which appertain to the reproduction, nutrition, and growth
of the new species, as the milk and semen, would be ad-
mitted.

In the second category, viz. that of unorganised fluids,
the perspirable fluid, the saliva, the bile, and the urine, as well
as probably the fluid of the pancreas, and of certain other
glandular organs would be found.

This arrangement of the fluids of the human body might
be represented tabularly, thus —

FLUIDS.

Organised. Unorganised.

1st series.

Normal :

Perspirable fluid.
Saliva.
Bile.
Urine.

Pancreatic fluid (?)
&c. &c. &c.

Lymph.
Chyle.
Blood.
Mucus.
Abnormal :

Pus.
2d series.

Milk.
Semen.

If the terms ORGANISED and UNORGANISED be objected to,
the words COMPOUND and SIMPLE might take their places,
and would well express the distinction which characterises
the two series of fluids, the former appellation being applied
to those fluids which are compounded of both a solid and a
fluid element, and the latter to those which do not possess
this double constitution.

ORGANISED FLUIDS.

ART. I. THE LYMPH AND THE CHYLE.

IT will perhaps render the description of the lymph and
the chyle more intelligible, if the observations which we shall
have to make on these fluids are preceded by a short sketch
of the lymphatic system itself. This system consists of
vessels and of glands, which are of the kind which has been
denominated conglobate. The vessels have many of the
characters of veins, commencing as mere radicles, which unite
with each other to form larger trunks, and their interior
surface is provided with valves : they arise from all parts of
the system, even the most remote ; those of the lower ex-
tremities and abdominal viscera form by their union the
thoracic duct, which, running along the left side of the spinal
column, unites with the left subclavian vein, near its junction
with the internal carotid, its contents becoming mingled with the
torrent of blood in that vein. The lymphatics of the left side
of the head and neck, as well as those of the arm of the
corresponding side, unite with the same thoracic duct in the
superior part of its course. On the right side, however, a
smaller separate duct formed by the union of the lymphatics
of the upper part of that side of the body, is frequently met
Avith, and this empties itself into the right subclavian vein.
All these lymphatic vessels, in their course, pass through
the glands above referred to, and in which the fluid or lymph
contained by them doubtless undergoes further elaboration.
The lymphatics are remarkable for their equal and small
diameter, which allows of the passage of the lymph through
them ' by mere capillary attraction ; they are also to be
regarded as the chief, though not the exclusive, agents of
absorption in the system, the veins likewise taking part in
this process.

B 2

4 ORGANISED FLUIDS.

The lymphatics of the upper and lower portions of the
body imbibe and carry along with them the various effete
matters and particles which are continually being given off by
the older solid constituents of our frame, and which are as
constantly undergoing a process of regeneration ; these they
redigest and reassimilate, into a fluid endowed with nutritive
properties, denominated lymph, and which is poured into the
thoracic duct.

Those lymphatics, however, which arise on the surface of
the small intestines, and which, passing through the mesentery,
join the thoracic duct, have received a special appellation,
being called lacteals: this name has been bestowed upon them
on account of the milk-like appearance of the fluid which
they contain, viz. the chyle, a fluid derived from the digestion
of the various articles of food introduced into the stomach,
and which also is emptied into the thoracic duct.

But the lacteals are not always filled with chyle ; they are
only to be found so when digestion has been fully accom-
plished ; when an animal is fasting, they, like other lymphatics,
contain merely lymph.

The contents of the thoracic duct likewise vary : it never
contains pure chyle, but during digestion a fluid composed of
both chyle and lymph, the former predominating, and di-
gestion being completed, it is filled with lymph only.

It follows therefore, that if we are desirous of ascertaining
the proper characters of chyle, our observations should not
be conducted on the fluid of the thoracic duct, but on that of
the lacteals themselves. It is a common error to regard and
to describe the contents of that duct, at all times, and under
all circumstances, as chyle, and it is one which has led to the
formation of some false conclusions.

We will describe first the lymph, next the chyle, and
lastly the mingled fluid presented to us in the thoracic duct.

The lymph is a transparent colourless liquid, exhibiting a
slightly alkaline reaction, and containing, according to the
analysis of Dr. G. O. Rees, 0*120 of fibrin, with merely a
trace of fatty matter.

When collected in any quantity, and left to itself, the
lymph, like the chyle, separates into a solid and a fluid

THE LYMPH AND THE CHYLE. 5

portion: the solid matter consists of fibrin, and contains
mixed up with its substance numerous granular and spherical
corpuscles, identical with the white globules of the blood;
the serum is transparent, and contains but few of the cor-
puscles referred to.

The chyle is a whitish, opaque, oleaginous, and thick fluid,
also manifesting an alkaline reaction, and containing, according
to the analysis of the gentleman above mentioned, 0*370 of
fibrin, and 3*601 of fatty matter.*

There are present in it solid matters of several kinds.

1st, Minute particles, described by Mr. Gulliverf, and which
constitute the " molecular base " of the chyle, imparting to it
colour and opacity : their size is estimated from the 3-^0 o to
the 2-¥]j oo °f an inch in diameter; they are "remarkable''
not only for their minuteness, but also for " their equal size,
their ready solubility in aether, and their unchangeableness
when subjected to the action of numerous other re-agents
which quickly affect the chyle globules."

Mr. Gulliver has ascertained the interesting fact, that the
milky appearance occasionally presented by the blood is due to
the presence of the molecules of the chyle. This peculiar
appearance of the blood, which so many observers have
observed and commented upon, but of which none save Mr.
Gulliver have offered any satisfactory explanation, is noticed
to occur especially in young and well-fed animals during
digestion ; as also in the human subject, in certain patholo-
gical conditions, and sometimes in connexion with a gouty
diathesis.

2nd, Granular Corpuscles, similar to those contained in
the lymph, and identical with the white globules of the
blood, but rather smaller than those, and which will be fully
and minutely described in the chapter on the Blood. Mr.
Gulliver, in his excellent article on the chyle, makes the
remark that the magnitude of the globules hardly differs,

* See article "Lymphatic System" by Mr. Lane, in Cyclopaedia of
Anatomy and Physiology, April, 1841.

t See Appendix to the translation of Gerber's General Anatomy,
p. 89.

6 ORGANISED FLUIDS.

from whatever part of the lacteal system they may have
been obtained.

The granular corpuscles are found but sparingly in the
chyle of the inferent lacteals, abundantly in that of the
mesenteric glands themselves, and in medium quantity in
the efferent lacteals, and in the fluid of the thoracic duct.

3rd, Oil Globules, which vary exceedingly in dimensions.

4th, Minute Spherules, probably albuminous, the exact
size or form of which it is difficult to estimate, and which
are not soluble in aether, as are those which constitute the
molecular base.

Chyle, when left to itself, like the lymph, separates into a
solid and fluid portion: the coagulum, however, is larger
and firmer than that of lymph, in consequence of the greater
quantity of fibrin which it contains ; it is also more opaque
from the presence, not merely of the white granular corpuscles,
but principally of the molecules of the chyle ; the serum is
likewise opaque, the opacity arising from the same cause,
the peculiar characteristic molecules of the chyle.

The lymph and the chyle may now be contrasted together.
Both are nutritive fluids, the nutritious ingredients contained
in the one being derived from the re-digestion of the various
matters which are constantly thrown off from the older solids,
those of the other being acquired from the food digested in
the stomach : the one is a transparent fluid, containing but
little fibrin, a trace only of oil, and but few white corpuscles ;
the other is an opaque, white, thick, and oily fluid, more rich
in fibrin, and laden with molecules, white corpuscles, oil
globules, and minute spherules; the one, therefore, is less
nutritive than the other.

It has been asserted that chyle until after its passage
through the mesenteric glands would not coagulate; the
fallacy of this assertion has been demonstrated by Mr. Lane*,
who collected the chyle previous to its entrance into those
glands, and found that it did coagulate, although with but
little firmness, less indeed than it exhibited subsequent to
its passage through the glands.

* See Art. " Lymphatic System," loc. cit.

THE LYMPH AND THE CHYLE. 7

We come now to consider the nature of the contents of the
thoracic duct.

These, as already stated, vary according to the condition
of the animal ; thus, if it be fasting, the duct contains only
lymph ; if, however, the contents be examined soon after a
full meal, they will be found to present nearly all the characters,
physical and vital, of the chyle, and in addition, especially
in the fluid obtained from the upper part of the duct, a pink
hue, said to be deepened by exposure to the air.

This red colour has been noticed by many observers,
and it is now generally agreed that it arises from the presence
in the fluid of the thoracic duct of numerous red blood
corpuscles.

The question is not as to the existence of blood discs in
that fluid, but as to the manner in which their presence
therein should be accounted for, whether it is to be regarded
as primary and essential, or as secondary and accidental.

Most observers agree in considering the presence of blood
discs in the chyle of the thoracic duct as accidental, although
they account for their existence in it in different ways.

The distinguished Hewson * detected blood corpuscles in
the efferent lymphatics of the spleen, which empty their con-
tents into the thoracic duct, and in this way he conceived
that the fluid of that vessel acquired its colour.

The accuracy of Hewson's observation, as to the lymphatics
of the spleen containing 'blood corpuscles, is confirmed by
Mr. Gulliver, of the fidelity, originality, and number of
whose remarks on the microscopic anatomy of the animal
fluids it is impossible to speak in terms of too high praise.
Mr. Gulliver detected blood corpuscles in the efferent lym-
phatics of the spleen of the ox and of the horse.

Miiller, and MM. Gruby and Delafont, attribute the
presence of blood discs in the chyle to the regurgitation of
a small quantity of blood from the subclavian vein : if
they are really foreign to the chyle, this is the most probable
channel of their ingress.

* Experimental Inquiries, part iii. Edited by Magnus Falkoner.
London, 1777, pp. 122. 112. 135.

B 4

8 OKGANISED FLUIDS.

Mr. Lane thinks that the division of the capillaries, which
necessarily takes place in the opening of the duct, allows of
the admission into its contents of the blood discs, which are
there found. Such are the several ways in which it has been
suggested that the blood corpuscles find entrance into the
thoracic duct.

Mr. Gulliver has noticed that the blood corpuscles con-
tained in the chyle are usually much smaller than those taken
from the heart of the same animal, and also, that not more
than one fourth of the entire number present their ordinary
disc-like figure, the remainder being irregularly indented on
the edges, or granulated. The first of these observations,
viz. that which refers to the smaller size of the blood cor-
puscles found in the chyle, might be explained by supposing
that those corpuscles were in progress of formation, and that
they had not as yet attained their full development ; the
other remark, as to the deformed and granulated character
of the corpuscles, might be reconciled with the former expla-
nation, by supposing that some time had elapsed between
the death of the animal and the examination of the fluid of
the thoracic duct. If this manner of accounting for the
condition presented by the blood corpuscles of the chyle
should be proved to be insufficient, which I myself scarcely
think it will, then the only other mode of explaining their
appearances is by supposing that their presence in the chyle
is really foreign, and that, soon after their entrance into that
fluid, the blood corpuscles begin to pass through those changes,
indicative of commencing decomposition, of which they are
so readily susceptible.

Leaving, however, for the present the question of the
origin of the red corpuscles of the blood, which will have to
be more fully discussed hereafter, we will in the next place
bestow a few reflections upon the origin of the white cor-
puscles : into this subject, however, it is not intended to
enter at any length at present, but merely to make such ob-
servations as seem more appropriately to find their place in
the chapter on the Chyle and Lymph.

It has been noticed that the white corpuscles occur in

THE LYMPH AND THE CHYLE.

very great numbers in the chyle obtained from the mesen-
teric and lymphatic glands : this observation has led to the
supposition that the white corpuscles are formed in those
glands.

Upon this question, as upon so many others, Comparative
Anatomy throws much light. It has been ascertained that
the glands referred to have no existence in the amphibia and
in fishes ; in birds, too, they are only found in the neck.
Thus it is evident, that the lymphatic glands, however much
they may contribute to the formation of the white corpuscles,
are not essential to their production.

Corpuscles, very analogous to those of the chyle and the
lymph, are found in vast quantities in the fluid of the
thymus gland in early life : these corpuscles Hewson con-
sidered to be identical with the globules of those fluids, and
therefore he regarded the thymus gland as an organ of nutri-
tion, and as an appendage to the lymphatic system. In this
opinion he has been followed by Mr. Gulliver. That it is
an organ of nutrition, adapted to the special exigencies of
early life, there can be no doubt ; but that it is an append-
age of the lymphatic system, and that the globules with
which it so abounds are the same as those of the lymph and
chyle, admits of much diversity of opinion.

The globules of the thymus have undoubtedly striking
points of resemblance with the corpuscles so frequently al-
luded to ; they have the same granular structure ; they are,
like them, colourless, and to some extent they comport them-
selves similarly under the influence of certain re-agents.

There are points, however, of dissimilarity as well as of
resemblance ; thus they are usually very much smaller than
the lymph corpuscles, they do not undergo any increase of
size when immersed in water, and acetic acid does not dis-
close the presence of nuclei.

But above all, the corpuscles of the thymus differ from
those of the lymph and chyle in their situation : those of the
latter fluids are always inclosed in vessels in lymphatics, or
lacteal lymphatics ; while those of the former fluid, that of
the thymus gland, are extravascu^ar, lying loosely in the

10 ORGANISED FLUIDS.

meshes of the cellular tissue which forms the foundation of
the substance of the gland itself.

Now it is impossible to conceive that solid organisms of such
a size as the corpuscles of the thymus can enter the lymphatics
bodily : — if they are received into the circulation at all, they
must first undergo a disintegration and dissolution of their
structure.

Both Mi*. Gulliver and Mr. Simon * regard the corpuscles
of the thymus as cy toblasts ; the former, however, believes
that before their development as cytoblasts they enter the
circulation, while the other conceives that they are developed
in the gland itself into true nucleated cells.

It is difficult to suppose with Mr. Simon, that the small
and uniform granular corpuscles of the thymus are developed
into the large, complex, and curiously constituted true
secreting cells of that gland.

Whether this be the case or not, however, it would appear
that Mr. Simon has fallen into a certain amount of error in
his account of the structure of the thymus gland, and also of
other analogous glands, as well as in the generalisations
deduced by him therefrom.

Thus Mr. Simon states, that in early life there exists in the
thymus gland " no trace whatever of complete cells ; " that it
is only in later life that nucleated cells are formed, and that
these are developed out of the granular corpuscles already
referred to, and which are alone present in the gland in
the first years of its existence. The same statements are
applied to the thyroid body.

But Mr. Simon does not rest here : he regards the long
persistence of the corpuscles, which he states are to be found
in all those glands which secrete into closed cavities, in the
condition of cytoblasts, as constituting a remarkable and
important distinction between the glands in question and the
true secreting glands which are furnished with excretory ducts.

These observations are to a considerable extent erroneous,
as is proved by the fact that true nucleated cells are to be met

* Prize Essay on the Thymus Gland. London, 4to, 184G.

THE LYMPH AND THE CHYLE. 11

with abundantly in the thymus gland of still-born children, and
also in the thyroid body and supra-renal capsule; in the
last, indeed, almost every cell is nucleated.

On this supposed essential structural distinction between
the true glands which are furnished with excretory ducts,
and those anomalous ones which are destitute of such ducts,
Mr. Simon founds some general deductions.

It is known that the functions performed by the glands
without ducts are of a periodic and temporary character, while
those discharged by the true glands are of a permanent and
constant nature.

It is also considered by some physiologists that the nucleus
of every nucleated cell is the only true and necessary secre-
ting structure.

These views of the nature of the functions performed by
the anomalous glands, and of the importance of the nucleus,
being adopted by Mr. Simon, he thence draws the inference
that the cytoblastic condition of the cells of the thyroid,
thymus, and other analogous glands, is precisely that which
is required by organs which are called only into action pe-
riodically, and in which great activity prevails at certain
periods.

This theory is ingenious, but it has been seen that the
main fact upon which it rests is for the most part erroneous,
and the basis of the theory being removed, the theory itself
must fall.

In order that it may be seen that the opinions entertained
by Mr. Simon, in his Essay on the Thymus, have not been
overstated, I will introduce a few passages therefrom : —

" Thus while the completion of cells, within the cavities
of the thyroid gland, is assuredly a departure from the habitual
state of that organ, and probably the evidence of protracted
activity therein ; it is yet just such a direction as may serve
even better than uniformity to illustrate the meaning of the
structures which present it ; for it shows, beyond dispute, that
the dotted corpuscles are homologous with the cytoblasts of
true glands." (p. 79.)

" In the thymus one would at first believe a similar low

12 ORGANISED FLUJDS.

stage of cell development to be universal ; for in examining
the contents of the gland in early life, one finds no trace
whatever of complete cells. The dotted corpuscles are un-
doubtedly quite similar to those which we have recognised as
becoming the nuclei of cells in the thyroid body, and in
other organs ; there is abundant room for conjecturing them
to be of a correspondent function — to be, in fact, true
cytoblasts; but the arguments for this point cannot be
considered quite conclusive, without some additional evi-
dence."

" The completion of a cell, from the isolation of so much of
the secreted product as is collected round each cytoblast, is a
very frequent secondary process. In the true glands it is
very frequent, in those without ducts exceptional" (p. 84.)

With one other remark on the corpuscles of the thymus,
we will conclude this short chapter : mixed up with those
corpuscles are frequently to be noticed many nucleated glo-
bules, in every way similar to the white corpuscles of the
blood, but very distinct from the true cell corpuscles of the
gland ; the nucleus of these white globules is of nearly the
same size as the dotted corpuscles themselves. Is there any
relation between this coincidence in size ?

We now pass to the consideration of the most important
fluid in the animal economy, viz. the blood. *

* Plate VIII. will contain figures illustrative of the chyle,

THE BLOOD. 13

ART. II. THE BLOOD.

OF all the fluids in the animal economy, the most interest-
ing and the most important is the Blood : and it is an appre-
ciation of this fact which has led to the concentration upon
its study, in times past as well as present, of the powers of a
host of able and gifted observers, whose labours have not
been without their reward.

The knowledge of this fluid acquired by the early physician
was of a very limited character, it being confined to the
observance of a certain number of external and obvious
appearances, such as the colour, consistence, and form of the
effused blood. Limited as this knowledge was, however,
compared with that which, in our favoured day, we enjoy, it
was yet not without its practical utility.

More recently the chemist, who is in these times extend-
ing in all directions so rapidly the boundaries of his domain,
has cast upon this particular portion of it a flood of light.
Who, to look upon a dark and discoloured mass of blood,
could imagine that the magic power of chemistry could
reveal in it the existence of not less than forty distinct and
essential substances?

Lastly, the micrographer, with zeal unweariable, has even
outstripped the progress of his rival the chemist, and brought
to light results of the highest importance. It is these results
that in this work we have more especially to consider.

In the following pages we shall have to treat of the blood
under various aspects and conditions ; we shall have to regard
it alive and dead, circulating within its vessels, and motion-
less without them ; as a fluid and as a solid ; healthy and
diseased ; or, in other words, we shall have to consider the
blood physiologically, pathologically, and anatomically.

'

DEFINITION.

The blood may be defined as an elaborated fluid, having
usually a specific gravity of about 1*055, that is, heavier than

14 ORGANISED FLUIDS.

water ; in mammalia and most vertebrate animals, being of a
red colour, but colourless in the invertebrata * ; circulating in
distinct sets of vessels, arteries, and veins ; holding in solu-
tion, all the elements of the animal fabric — fibrin, albumen,
and serum, together with various salts and bases, and in
suspension, myriads of solid particles termed globules, f

The blood would thus appear to be the grand supporter
and regenerator of the system ; in early life, supplying the
materials necessary for the development of the frame, and,
in adult existence, furnishing those required for its main-
tenance: hence "the blood" has been figuratively called
" the life."

COAGULATION OF THE BLOOD, WITHOUT THE BODY.

The first change which the blood undergoes subsequent to
its removal from the body consists in its coagulation. This
phenomenon has been denominated emphatically " the death
of the blood," because, when it has once occurred, the blood
is thereby rendered unfit to maintain the vital functions,
and there is no known power which can restore to it that
faculty.

Although the word coagulation is usually applied generally
to the blood, yet it is not to be understood that the whole of
the mass of that fluid undergoes the change of condition
implied by the term coagulation, which affects but a single
element of the blood, — viz. the fibrin.

The precise circumstances to which the coagulation of the

* Miiller states that the quantity of blood in the system varies from eight
to thirty pounds, and Valentin found that the mean quantity of blood
in the male adult, at the time when the weight of the body is greatest,
viz. at thirty years, is about thirty-four and a half pounds, and in the
adult female, at fifty years, when the weight of the body in that sex is at
its maximum, about twenty-six pounds. According also to Miiller, the
specific gravity of the blood varies from P527 to 1'057 ; arterial blood is
lighter than venous.

f In one vertebrate animal, a fish, Branchiostoma lubricum Costa, the
blood is colourless, and in the most of Annelida it is red ; the red colour,
however, exists in the liquor sanguinis, and not in the blood corpuscles.

THE BLOOD. 15

blood is due, have never as yet been satisfactorily explained
and determined. Some have conceived that it resulted from
the escape of a vital air or essence. Much has been said and
written upon this " vital principle/' and, it seems to me, with
very little profit. It would be more philosophical, I think,
to regard animal life not as an essence, or ether, but as the
complex operation of nicely adjusted scientific adaptations
and principles. According to this view, the human frame in
health would be comparable (and yet, withal, how incom-
parable is it !) to a finely-balanced machine, in which action
and reaction are proportionate, and in disease disproportion-
ate, the injury to the machine being equivalent to the dis-
proportion between the two forces. *

The coagulation of the .blood, in some degree, doubtless
depends upon the operation of the following causes, each con-
tributing in a greater or lesser degree to the result ; namely,
the cessation of nervous influence, the abstraction of caloric,
the exercise of chemical affinity between the particles of
fibrin, and, lastly, a state of rest : between motion and life a
very close connexion appears to exist. |

Formation of the Clot.

A portion of blood having been abstracted from the
system, and allowed to remain for a few minutes in a state
of quiescence, in a basin or other suitable vessel, soon mani-
fests a change of condition. This consists in the separation
of the fibrin and globules of the blood, which go to form the
clot, from the serum, which holds in solution the various salts
of the blood. In this way a rude and natural analysis is
brought about; the fibrin, being heavier than the serum,
falls to the bottom, and, by reason of its coherence and con-

* It is hoped that the preceding brief remarks will not expose the
wrJtertothe charge of being a Materialist ; between animal life and mind
an essential distinction exists.

f '* Fresh blood if exposed to a very low temperature freezes, and may
in that state be preserved, so as to be still susceptible of coagulation when
thawed." — MULLER.

16 ORGANISED FLUIDS.

tractility, forms a compact mass or clot, the diameter of
which is less than that of the vessel in which it is contained ;
while the lighter serum floats on the top and in the space
around the clot.

Now the only active agent in this change in the arrange-
ment of the different constituents of the blood, is the fibrin ;
and although the globules of the blood constitute a portion
of the clot, yet they take no direct part in its formation, and
their presence in it is thus accounted for; the fibrin, in
coagulating, assumes a filamentous and reticular structure,
in the meshes of which the globules become entangled, and
thus are made to contribute to the composition of the clot, the
bulk of which they increase, and to which they impart the
red colour.

It was an ancient theory that the clot was formed solely
by the union of the globules with each other. The fallacy
of this opinion is easily demonstrated by the two following
decisive experiments : —

The first is that of Miiller, on the blood of the frog, who
separated, by means of a filter, the globules from the fibrin,
the latter still forming a clot, although deprived of the glo-
bules. This experiment is not, however, applicable to the
blood of man, or of mammalia in general, the globules in
these being too small to be retained by the filter. The second
expedient is, however, perfectly suited to the human blood.
It is well known that if blood, immediately after its removal
from the body, be stirred with a stick, the fibrin will adhere
to it in the form of shreds : the blood being defibrinated by
this means, the globules fall to the bottom of the basin in
which the blood is contained, on account of their gravity ;
but they do not cohere so as to form a clot, remaining dis-
connected and loose.

It is difficult to determine the exact time which the blood
takes to coagulate, because this coagulation is not the work of
a moment ; but, from its commencement to its completion, the
process occupies usually several minutes. The first evidence
of the formation of the clot, is the appearance of a thin and
greenish serum on the surface of the blood, in which may be

THE BLOOD. 17

seen numerous delicate fibres, the arrangement of which
may be compared to that of the needle-like crystals contained
in the solution of a salt in which crystallisation has com-
menced. Estimating, however, the coagulation neither from
its commencement nor from the complete formation and con-
solidation of the clot, but from the mean time between these
two points, it will generally be found that healthy blood
coagulates in from fifteen to twenty minutes.

In diseased states of the system, however, the time occu-
pied in the coagulation of the blood, or, in other words, in
the formation of the crassamentum, or clot, varies very con-
siderably ; and it is of much practical importance that the
principle which regulates this diversity should be clearly
understood.

In disorders of an acute, active, or sthenic character, in
which the vital energies may be regarded as in excess, as,
for instance, in inflammatory affections, in pneumonia, pleu-
risy, acute rheumatism, and sanguineous apoplexy : in febrile
states of the system, as in the commencement of some fevers,
as in ague, plethora, and as in utero-gestation, the blood
takes a much longer time than ordinary to coagulate, no
traces of this change in the passage of the blood from a fluid
to a solid state being apparent until from sixteen to twenty
minutes have elapsed. This length of time may be accounted
for, by supposing that, in the affections named, the blood is
endowed with a higher degree of vitality, and that therefore
a longer period is required for its death to ensue; or, in
other words, if the expression may be allowed, that the blood
in such cases dies hard. On the contrary, in disorders of a
chronic, passive, or asthenic character, in all of which there
is deficiency of the vital powers, as in typhus, anemia,
chlorosis, the blood passes to a solid state in a much shorter
period than ordinary, even in from five to ten minutes. In
these cases the vitality of the blood is very feeble, and it
may be said to die easily. A remarkable difference is like-
wise observable in the characters of the clot formed in the
two classes of disorders named ; in the first it is firm, and

18 ORGANISED FLUIDS.

well defined; in the second, soft, and diffluent.* To this sub-
ject we shall have occasion again to refer, more at length.

Fibrin, if left at rest for a time, undergoes a softening
process, and breaks up into an extremely minute granular
substance. This softening of the fibrin has been improperly
confounded with suppuration ; the softened mass, however,
may be distinguished from true pus by the almost complete
absence of pus globules. This peculiar change in the con-
dition of the fibrin has been noticed to occur both in blood
contained within and without the body, and large softened
clots of it are not unfrequently encountered in the heart
after death. The process always commences in the centre
of these clots.

Formation of the Biiffy Coat of the Blood.

Surmounting the coloured portion of the clot is observed,
in blood taken from the system in inflammatory states, a
yellowish green stratum : this constitutes the buffy or
inflammatory crust, the presence of which was deemed of
so much importance by the ancient physician, and which is
indeed not without its pathological value. This crust con-
sists of fibrin deprived of the red globules of the blood ; and
its mode of formation is thus easily and satisfactorily ex-
plained. Of the constituents of the blood, the red globules
are the heaviest: now, supposing that no solidification of
any one element were to take place, these, of course, would
always be found occupying the lowest position in the contain-
ing vessel ; the fibrin would take the second rank, and the
serum the third : but such, under ordinary circumstances, not
being the case, and the fibrin coagulating so speedily, the
globules become entangled in its meshes before they have
had sufficient time given them to enable them to obey fully
the impulse derived from their greater specific gravity ; and
thus no crust is formed. In blood drawn in inflammations,

* It is to be remarked, that the clot is not of equal density throughout,
but that its lower portion is invariably softer than the upper, and this is
accounted for by the fact of its containing less fibrin.

THE BLOOD. 19

however, this coagulation, as already stated, proceeds much
more slowly; and thus time is allowed to the globules to
follow this impulse of the law of gravity to such an extent,
as that they fall a certain distance, about the sixteenth of an
inch, usually, below the surface of the fibrin before its com-
plete coagulation averts their further progress ; and a portion
of which is thus left colourless, which constitutes the buffy
and so called inflammatory crust of the blood. But there
are other considerations to which it is necessary to attend,
and which contribute to the formation of the buffy coat.

One of these is the greater relative amount of fibrin which
inflammatory blood contains.

A second is the increased disposition, first pointed out by
Professor Nasse, which the red corpuscles have in inflam-
matory blood to adhere together and to form rolls, and the
consequence of which is that they occupy less space in the
clot.

A third additional consideration, to which it is necessary
to attend, in reference to the formation of the inflammatory
crust, is the density of the blood, which bears no exact
relation to the amount of fibrin, but depends rather upon
the quantity of albumen which it contains. * The greater the
density of the blood, the longer would the globules take to
subside in that fluid; and the less its density, the shorter
would that period be. Now inflammatory blood is usually of
high density, while with that of feeble vitality, the reverse
obtains. Thus were it not for the fact, that in blood in the
first state, coagulation is slow, and in the second quick, the
blood of weak vital power would be that in which, a priori,
we should expect to see the buffy coat most frequently
formed ; but the much greater rapidity in the coagulation of
the blood more than counterbalances the effect of density.

The blood, then, may be so dense, that although at the
same time it coagulates very slowly, yet no inflammatory
crust be formed, the patient from whom the blood is extracted

* It has been remarked, that in alburninuria, in which a considerable
portion of the albumen of the system passes off with the urine, the blood
possesses a very feeble density.

c 2

20 OKGANIBED FLUIDS.

labouring all the while under severe inflammation. An
ignorance of this fact has been the source of many great and
perhaps fatal errors, on the part of those physicians who have
been used to regard the presence of the buffy coat as an un-
doubted evidence of the existence of inflammation, and its
absence as indicating immunity therefrom. It has been
remarked that, in the first bleedings of pneumonic patients,
the blood often wants the buffy coat : this is attributed to
its greater density, and which is found to diminish with each
succeeding abstraction of blood ; so that if inflammation be
present, the characteristic coat is usually apparent also after
the second bleeding.

The conditions, then, favourable to the formation of the
buffy coat, are a mean density of the blood, slow coagulation ;
excess of fibrin, and increased disposition to adherence on the
part of the red corpuscles.

Other circumstances doubtless exist, which in a minor
degree affect the formation of the crust : such as the density
of the globules, and the qualities of the fibrin itself. Into
these it is unnecessary to enter, as they do not vitiate the
accuracy of the general statements.

The Cupping of the Clot.

At the same time that the crassamentum exhibits the
buffy coat, the upper surface of the clot is very generally
also cupped. This cupping of the clot arises from the con-
traction of that portion of the fibrin which constitutes the
buffy stratum, and which contraction operates with greater
force on account of the absence in it of the red corpuscles of
the blood. The degree to which the clot is cupped, therefore,
probably is in direct relation with the thickness of the crust.
Its presence was also regarded as an indication of the existence
of inflammation, the amount of cupping denoting the extent
of inflammation. This sign is not, however, any more than
that afforded by the buffy coat, to be considered as an in-
variable criterion of the existence of inflammation.*

* Professor Nasse has pointed out a mottled appearance which is

THE BLOOD. 21

COAGULATION OF THE BLOOD, IN THE VESSELS, AFTER

DEATH.

The coagulation, or death, which we have described as
occurring in blood abstracted from the system by venesection,
takes place likewise, — the vital influence which maintains the
circulation being removed, — in that which is still contained
within the vessels of the body, although in a manner less
marked and appreciable.

As also in the case of the blood withdrawn from the system,
the time occupied in the coagulation of that which is still
enclosed in its own proper vessels, varies very considerably.
This difference depends partly upon the circumstances under
which the patient has died, whether he has been exhausted or
not by a previous long and wasting illness, and partly upon
temperature and, perhaps, certain electric states of the
atmosphere. In all instances, however, a much longer period
is required for the production of coagulation in blood not
removed from the body, than in that which has been with-
drawn by bleeding ; this change in its condition being seldom
effected, in the former instance, in a shorter period than from
twelve to twenty-four hours subsequent to decease ; although
occasionally, but rarely, it may occur at periods either earlier
or later than those named.

Signs of Death. — It has already been stated, that blood
once coagulated is rendered unfit for the purposes of life,
and that no known means exist capable of restoring to
coagulated blood its fluid state, so as to render it once again

frequently observed to precede the formation of the buffy coat, and the
existence of which he states to be quite characteristic of inflammatory
blood. This appearance is produced in the following manner : after the
lapse of a minute or two a peculiar heaving motion of the threads or rolls
formed by the union of the red corpuscles with each other is observed to
take place ; this results in the breaking up of the rolls, the corpuscles of
which now collect into masses, leaving, however, intervals between them,
and which become filled with fibrin ; now it is the contrast in colour
between this fibrin and the masses of red corpuscles which occasions the
blood in coagulating to assume the mottled aspdct referred to.

c 3

22 ORGANISED FLUIDS.

suited to play its part in the maintenance of the vital func-
tions. The accuracy of these statements is attested by
physiology, which demonstrates to us that a fluid condition is
necessary to the blood, for the correct performance of its
allotted functions. It follows, then, from the foregoing, that
a coagulated state of the blood, not in a single vessel indeed,
but in the vessels of the system generally, affords a certain
indication that death has occurred, and that therefore a
return to life has become impossible.

It has ever been an object of the highest importance to
distinguish real from apparent death ; and anxious searches
have been instituted in the hope of discovering some certain
sign whereby the occurrence of death is at once signalised.
Hitherto this inquiry has been unsuccessful ; and it could hardly
have been otherwise ; for before the physiologist will be able
to determine the precise moment when life ceases, and death
begins, he must know in what the life consists, for death is
but the negation of life. It is probable that the mystery
of life will never be revealed to man ; if, indeed, it be any
thing more than, as already hinted, the result of the com-
bined operation of various chemical and physical laws ap-
pertaining to matter.

Although no one single sign has hitherto been discovered
indicative of death at the moment of its occurrence, yet
several appearances have been remarked some time after
death, all of which are of more or less value in determining
so important a point. Independently of the cessation of
respiration and circulation, the presence of muscular rigidity,
some other changes have been noticed to occur in different
parts of the human body soon after the extinction of life ; as,
for instance, in the eye, and in the skin : these are mostly,
however, symptomatic of incipient decomposition, arid the
time of their accession is very uncertain : they likewise affect
parts, the integrity of which is not essential to life. A
fluid state of the blood, on the contrary, has been shown to
be indispensable to life ; so that the change which it under-
goes in the vessels of the body so quickly after death, may
be employed with much advantage and certainty in de-

THE BLOOD. 23

termining, in doubtful cases, whether life has become extinct
or not.

It is by no means difficult to establish the fact of the
coagulation of the blood in the vessels after death. If a vein
be opened, as in the ordinary operation of bleeding, in a
person who has just died, the blood will issue in a fluid state,
as in life ; but it will not leap forth in a stream. If a little
of the blood, thus procured, be preserved in a small glass,
we shall soon remark the occurrence of coagulation in it,
from which we shall know that the fibrin within the vessels
has not as yet assumed a solid form. If we repeat this
operation at the end of about eighteen hours, we shall obtain
only a small quantity of reddish serum, in which, on being
set aside for a time, no crassamentum will be found, the only
change occurring in this serum consisting in the subsidence
of the few red globules which were previously suspended in
it, and which now form, at the bottom of the glass, a loose
and powdery mass. By this experiment, which may be
repeated on several veins, and even on an artery, we have
clearly established the fact of the coagulation of the blood
within the vessels of the body, and therefore have ascertained,
in a manner the most satisfactory, that life is extinct.

In some instances, the blood is said to remain fluid after
death : this statement is not strictly correct, as a careful
examination of such blood will always lead to the detection
of some traces of coagulation. To the subject of the fluid
condition of the blood after death, we shall have hereafter to
return, in treating of the pathology of the blood.

When it is recollected that the heat of some climates, and
the laws and usages of other countries, compel the interment
of the dead a very few hours after decease, the importance
of this inquiry will become apparent ; and the value of any
sign which more certainly indicates death than those usually
relied upon in determining this question, will be more fully
appreciated.

It cannot be doubted but that, from the insufficient nature
of the signs of death usually regarded as decisive, premature
interment does occasionally take place; and it is probable

c 4

24 ORGANISED FLUIDS.

that this occurrence is far less unfrequent than is generally
supposed, and that for each discovered case, a hundred occur
in which the fatal mistake is never brought to light, it being
buried with the victim of either ignorance or carelessness.*

We have now to proceed to the anatomical consideration
of the blood : we have to pass to the description of the solid
constituents of that fluid, the globules; to describe their
different kinds, their form, their dimensions and their struc-
ture ; their origin, their development, and their destination
their properties, and their uses.

THE GLOBULES OF THE BLOOD.

The blood is not an homogeneous fluid, but holds in sus-
pension throughout its substance a number of solid particles,
termed globules. These serve to indicate to the eye the
motion of the blood ; and were it not for their presence, we
should be unable to establish, microscopically, the fact of the
existence of a circulation, to mark its course, and to estimate
the relative speed of the current in arteries and veins under
different circumstances.

These globules are so abundant in the blood, that a single
drop contains very many thousands of them, and yet they
are not so minute but that their form, size, and structure,
with good microscopes, can be clearly ascertained and defined.
They are not all of one kind, but three different descriptions
have been detected — the red globules, the white, and certain
smaller particles, termed molecules. We shall take each of
them in order; and notice, in the first place, the red glo-
bules, f

* The coagulation of the blood may be retarded or altogether prevented
by its admixture with various saline matters : to this point we shall have
occasion to refer more fully hereafter.

j" Malpighi first signalised the existence of the red globules in the blood,
so far back as 1665 : he regarded them as of an oily nature. The words
in which this discovery was recorded were as follow : — " Sanguineum
nempe vas in omento hystricis ... in quo globuli pinguedinis propria
figura terminati rubescentes et corallorum rubrorum vulgo coronam

THE BLOOD. 25

THE RED GLOBULES.

The number of red globules existing in the blood surpasses
by many times that of the white. To the sight, when seen
circulating in this fluid, they appear to constitute almost the
entire of its bulk. We shall now have to consider their
form, the size, the structure, and the properties by which
they are characterised.

Form. — In man, and in most mammalia, the red blood
corpuscles are of a circular but flattened form, with rounded
edges, and a central depression on each surface, the depth
of which varies according to the amount of the contents of
each globule.* Such is the normal form of the blood discs,
or the shape proper to them while circulating in the blood
of an adult. (See Plate I. fig. 1.) In that of the embryo,
the depression is wanting, and the globules are simply
lenticular, f

The blood globules, however, like all minute vesicles,
possess the properties of endosmosis and exosmosis. These
principles depend for their operation upon the different re-
lative density of two fluids, the one external to the vesicle,
the other internal. When these two fluids are of equal
density, then no change in the normal form of the vesicles
occurs : when, however, the internal fluid is of greater
density than the external, then an alteration of shape does
take place ; endosmosis ensues, in which phenomenon a por-
tion of the liquid without the vesicle passes through its

femulantes . . ." — De Omento et adiposis Ductibus. Opera omnia.
Lond. 1686.

Leeuwenhoek was, however, the first observer who distinctly described
the blood globules in the different classes of animals: this he did in 1673.
These historical reminiscences are not without their interest, and further
references of this kind will be introduced in the course of the work.

* The central depression was first noticed by Dr. Young. The
flattened form with the central depression on each surface, and of which
a bi-concave lens would form an apt illustration, is that which any vesicle
partially emptied of its contents would assume.

•f Hewson figured the difference in the form of the blood globule in the
embryo, and in the adult, in the common domestic fowl, and in the viper.

26 ORGANISED FLUIDS.

investing membrane, and thus distends and modifies its form.
Lastly, when a reverse disposition of the fluids exists, a con-
trary effect becomes manifested ; exosmosis is the result ;
which implies the escape of a portion of the contents of the
vesicle into the medium which surrounds and envelopes it.
The operation of these principles are beautifully seen, not
merely in the blood globules, but more especially in those
exquisitely delicate formations, the pollen granules.

Between the density of the liquid contained within the
red globules, and that of the liquor sanguinis, in states of
health, a nice adaptation or harmony exists, whereby these
globules are enabled to retain their peculiar form. There is,
however, scarcely any other fluid which can be applied to
the globules which does not, more or less, affect their shape,
most of the reagents employed in their examination rendering
them spherical. (See Plate I. Jig. 3.)

From the preceding observations, therefore, it follows that
the red globules, to be seen in their normal condition, should
be examined while still floating in the serum : they are best
obtained by pricking the finger with a needle or lancet.

Usually, when the microscope is brought to bear upon
the object-glass, the globules are seen to be scattered irre-
gularly over its surface, the majority of them presenting
their entire disc to view, others lying obliquely, so as to
render apparent the central depression, and others again
exhibiting their thin edges. (See Plate I. fig. 1.) Not un-
frequently, however, a number of corpuscles unite together
by their flat surfaces, so as to form little threads, comparable
to strings of beads, or of coins, which are more or less curved,
and in which the lines of junction between the corpuscles are
plainly visible. These strings of compressed globules bear
also a close resemblance to an Oscillatoria, and a still closer
likeness to the plant described in the history of the British
Freshwater Alga3, under the name of Hcematococcus ffooker-
iana. (See Plate I. fig. 4.) The cause which determines
this union of the cells still requires to be explained, and
would seem to be referable to a mutual attraction exerted
by the globules on each other. Andral asserts that when

THE BLOOD. 27

the fibrin of the blood is abstracted, they do not thus cohere.
Professor Nasse, as already remarked, states that this dispo-
sition on the part of the red corpuscles to unite together and
form rolls (as of miniature money in appearance), is increased
in inflammatory blood. The union does not, however, last
long ; a heaving to and fro of the strings of corpuscles soon
taking place, and which terminates in their disruption.*

Size. — The size of the red corpuscles of the blood, although
more uniform than that of the white, is nevertheless subject
to considerable variation. Thus, the globules contained in
a single drop of blood are not all of the same dimensions,
but vary much. These variations are, however, confined
within certain limits : the usual measurement in the human
subject is estimated at about the ^j^o °^ an incn; but,
occasionally, globules are met with not exceeding the 4/45 '•>
and, again, others are encountered of the magnitude of the
75 2T-g °f an i110*1 : these are? however, the extreme sizes
which present themselves. f The difference in the size of the

* In reptiles, birds, and fishes, the red globules are elliptical, a form
possessed also by some few mammalia, chiefly of the family Camelidce.
This fact was first discovered by Mandl, in the dromedary and paco ; and
subsequently by Gulliver, in the vicugna and llama. The oval globules
of these animals, however, could not be confounded with those of reptiles,
birds, and fishes, than the corpuscles of which they are so much smaller,
and, further, are destitute of the central nucleus, which characterises the
blood globules of all the vertebrata, the mammalia alone excepted. The
long diameter of the blood corpuscles of the dromedary, Mr. Gulliver
states to be the -g^V^ of an inch, and its short the ^-g^-j- ; the first of these
measurements exceeds but little the diameter of the human blood cor-
puscles.

Amongst fishes one exception to the usual oval form of the blood
corpuscle has been met with: this occurs in the lamprey, the blood disc of
which Professor Rudolph Wagner observed to be circular ; in form then
the blood corpuscle of the lamprey agrees with that of the mammalia, but
in the presence of a nucleus, the existence of which has been recently
ascertained by Mr. T. W. Jones, it corresponds with the structure of the
blood discs of other fishes.

t The first measurement given is that which is usually adopted by
writers ; the last two are those made by Mr. Bowerbank for Mr. Owen,
and which are to be found in the latter gentleman's paper on the Com-
parative Anatomy of the Blood Discs, inserted in the Lond. Mod. Gazette

ORGANISED FLUIDS.

red corpuscles, which has been indicated, is a character com-
mon to them in the blood of all persons, and at every age.
Another variation as to size exists, which is, that the cor-
puscles are larger in the embryonic and foetal than they are
in adult existence.* This observation is important, inasmuch
as it seems to prove that the blood does not pass directly
from the maternal system into the fcetal circulation, but that
the corpuscles are formed independently in the fcetus. In
states of disease, also, it has been remarked by Mr. Gulliver
that there is even a still greater want of uniformity in the
measurements presented by the red corpuscles.

A careful examination of the elaborate tables of Mr. Gul-
liver on the measurements of the blood corpuscles, appended
to the translation of Gerber's Minute Anatomy, tends to
show that a general, though not a very close or uniform
relation, exists between the size of the blood corpuscles
amongst the mammalia, and that of the animal from which
they proceed. These tables furnish more evidence in favour
of this co-relation than they do in support of the assertion
that has been made, that the dimensions of the corpuscle
depend upon the nature of the food. It would appear,
however, nevertheless, that the corpuscles of omnivora are
usually larger than those of carnivora, and these, again,
larger than those of herbivora.^ In a perfectly natural family

for 1839. The measurements which I have made of the human blood
corpuscle do not accord with those which are generally regarded as
correct : thus I find the average diameter of the blood globule of man to
be, when examined in the serum of the blood, about the Tr-ginr of an inch,
and in water in which the corpuscles are smaller, as a necessary con-
sequence of the change of form, the -g^Vo- The micrometer employed by
me is a glass one, precisely similar to that made use of by Mr. Gulliver,
being furnished to me by the same eminent optician, Mr. Ross, from whom
his own was obtained.

* This is the opinion of Hewson, Prevost, and Gulliver, and I have
myself to some extent confirmed its accuracy.

f The largest globules which have as yet been discovered, are those of
the elephant ; the next in size, those of the capybara and rhinoceros ; the
smallest, according to the observations of Mr. Gulliver, are those of the napu
musk-deer. The corpuscles of the blood of the goat were formerly con-

THE BLOOD. 29

of mammalia, as the rodents or the ruminants, there is also
an obvious relation between the size of the corpuscle and that
of the animal.

Grerber states that there is an exact relation between the
size of the blood globules and that of the smallest capillaries.
This observation is doubtless strictly correct.

Structure. — Much diversity of opinion has, until recently,
prevailed, and does still obtain, although to a less extent, in
reference to the intimate structure of the red globule. This
diversity has arisen partly from the imperfections of the
earlier microscopic instruments employed in the investigation,
and in part is due to the different circumstances in which
observers have examined the blood corpuscle. Thus, one
micrographer would make his observations upon it in one
fluid, and another in some other medium, opposite results
and conclusions not unfrequently being the results of such
uncertain proceedings. These discrepancies it will be the
writer's endeavour, as far as possible, to reconcile with each
other, as well as to point out those observations which are
entitled to our implicit belief, and those which yet require
confirmation. This being done, we shall be in a position to
form some certain conclusions. The earlier microscopic
observers believed, almost without exception, in the existence
of a nucleus in the centre of each blood corpuscle. Into this
belief they were no doubt led more from analogy than
from actual observation. Now analogy, although frequently
useful in the elucidation of obscure points, affords in the
present instance but negative and uncertain evidence. In
the elliptical blood discs of reptiles, birds, and fishes, a solid
granular nucleus does undoubtedly exist ; but the best optical
instruments, in the hands of the most skilful recent micro-

sidered to be the smallest. The following are the dimensions given by Mr.
Gulliver of some of the animals above named. Diameter of corpuscle of
the felephant, the ^^^ °f an incn » °f capybara, the -S^TS > °^ 8"oat» *^c
iraW 5 an(l of naPu musk-deer T^-J^- The white corpuscles of the musk-
deer are as large as those of a man ; a proof that the red corpuscles are
not formed, as many suppose, out of the colourless blood globules. (See
the figs.)

30 ORGANISED FLUIDS.

graphers, aided by the application of a variety of re-agents,
have failed, utterly, in detecting the presence of a similar
structure in the blood globule of the human subject in
particular, and of mammalia in general. I therefore do not
hesitate to join my opinion to that of those observers who
deny the existence of a nucleus in the blood discs of man
and mammalia.*

The appearance of a nucleus is, indeed, occasionally pre-
sented; but this appearance has been wrongly interpreted.
An internal small ring, under favourable circumstances, may
be seen in the centre of each blood corpuscle : this ring
is occasioned by the central depression, the outer margin of
which it describes ; and it was the observance of it that gave
to Delia Torre the erroneous impression, that each globule
had a central perforation, and therefore was of an annular
form ; and further, probably induced Dr. Martin Barry to
describe it as a fibre.

The very existence, on both surfaces of the blood disc, of
a deep central depression, together with its little thickness,
almost preclude the possibility of the presence of a nucleus.

An endeavour to account for the absence of a nucleus in
the blood corpuscle of the human adult has been made by
supposing that it does really exist in the blood of the embryo.
The answer to this supposition is, that no nucleus is to be
found in embryonic blood, and that if it were, it would be no
reason why the nucleus should not also be met with in the
blood of the adult, seeing that the blood disc is not a perma-
nent structure, as an eye or a limb, but one which is per-
petually subject to destruction and renewal.

Having then arrived at the conclusion that no nucleus
exists in the blood corpuscle of man, \ve have now to ask
ourselves the question, what, then, is really the constitution of
the red blood globule ?

* Amongst those who have asserted their belief in the presence of a
nucleus, may be mentioned Hewson, Miiller, Gerber, Mandl, Barry,
Wagner, Rees, Lane, and Addison; and of those who have held a contrary
opinion, Majendie, Hodgkiu, Liston, Young, Quekett, Gulliver, Lain-
botte, Owen, and Donne.

THE BLOOD. 31

Some observers have compared it to a vesicle. This defini-
tion does not seem to be altogether satisfactory ; for although
each corpuscle possesses the endosmotic properties common to
a vesicle, no membrane, apart from the general substance of
the globule, (I speak more particularly of the human blood
disc,) has been demonstrated as belonging to it,

Each globule in man may therefore be defined to be an
organism of a definite form and homogeneous structure,
composed chiefly of the proteine compound globuline, which
resembles albumen very closely in its properties; its sub-
stance externally being more dense than internally, it being
endowed with great plastic properties, and, finally, being the
seat of the colouring matter of the blood.

The extent to which the red globule is capable of
altering its form, is truly remarkable. If it be observed
during circulation, it will be seen to undergo an endless va-
riety of shapes, by which it accommodates itself to the space
through which it has to traverse, and to the pressure of the
surrounding globules. The form thus impressed upon it is not
however permanent, for as soon as the pressure is removed, it
again instantaneously resumes its normal proportions. On
the field of the microscope, however, the corpuscles may be so
far put out of form, as to be incapable of restoration to their
original shape.

Some observers have assigned to the red globule a com-
pound cellular structure, comparing it to a mulberry. It
need scarcely be said that such a structure does not really
belong to it. A puckered or irregular outline is not un-
frequently presented by many globules : this is due sometimes
to evaporation, and then arises from the presence around the
margin of the disc, and occasionally over the whole surface,
of minute bubbles of air*; and at other times it is the result of
commencing decomposition, or the application of some special
re-a^ent, as a solution of salt, in which cases a true change
in the form, but not in the structure of the globule, does

* This vesiculated appearance of the blocxTcorpuscles may be produced
at once by pressure.

32 ORGANISED FLUIDS.

really occur; its outline becomes irregular, and the surface
presents numerous short and obtuse points or spines.* Globules
in this state bear some resemblance to the pollen granules of
the order Composites.^ (See Plate 1.^. 5.)

* Mr. Wharton Jones says, " the granulated appearance " seems to be
owing to a contraction of the inner and a wrinkling of the outer of the
two layers of which he conceives the wall of the corpuscle to be formed.

f Th2 opinions promulgated by some observers in reference to the
intimate structure of the blood corpuscle are singular, and are rendered
interesting mainly by reason of the ingenuity of the views expressed.
Mr. Addison remarks ', "Blood corpuscles, therefore, appear to consist of
two elastic vesicles, one within the other, and to possess the following
structure, 1st, an external and highly elastic tunic, forming the outer
vesicle ; 2nd, an inner elastic tunic forming the interior vesicle ; 3rd, a
coloured matter occupying the space between the two tunics ; and 4th, a
peculiar matter forming the central portion of the corpuscle." Mr.
Wharton Jones 2 ascribes a somewhat similar constitution to the blood
corpuscle. " The thick wall of the red corpuscle," he says, " consists of two
layers. The outer is transparent, colourless, structureless, and resisting,
and constitutes about one half of the whole thickness of the wall. The
inner layer is softer and less resisting ; and is that which is the seat of the
colouring matter. Dr. G. O. Rees and Mr. Lane 3 describe the blood cor-
puscle as containing a fluid and provided with a nucleus composed of
a thin and colourless substance. The views of Dr. Martin Barry are,
however, the most peculiar of any ever yet published in reference
to the blood corpuscle ; when first they were announced in the pages
of the Philosophical Transactions, the scientific world were taken
by surprise and wonderment. Microscopes which had long been
suffered to remain undisturbed on their shelves were immediately
had recourse to, and many scientific men who previously had never
employed the instrument in their investigations, were induced to pro-
cure it, in order that they might themselves bear ocular witness of
the astonishing facts related by Dr, Barry in reference to blood corpuscles.
A short abstract of Dr. Barry's views will be read by some with interest.
Dr. Barry considers, that the molecules, the red corpuscles, and the
white globules, are different states of the developernent of the same
structure, the true blood globule. (This is also the opinion of Addison
and Donne.) The first he denominates a " disc," and the last a " parent

1 Experimental Researches, pp. 236, 237. Transactions of Prov. Med.
and Surg. Association.

2 See British and Foreign Medical Review, No. xxvm.

3 Guy's Hospital Reports, 1840.

THE BLOOt). 33

Colour. — The hamatine, or colouring matter of the blood,
seems in the red corpuscle of the mammalia to be diffused
generally throughout its substance; in the oviparous verte-
brata, however, it is confined to that portion of each corpuscle

cell." These different stages in the developeraent of the blood globule,
Dr. Barry compares with similar conditions of the germinal vesicle of
the ovum. " The disc," he says, " is the most primitive object we are
acquainted with ;" that it is synonymous with the "nucleus " of most au-
thors and the " basin-shaped granules" of Vogel ; that it " contains a cavity,
or depression," " the nucleolus," which " is the situation of the future
orifice," which he says, the blood corpuscle in certain states exhibits, and
" by means of which there is a communication between the exterior of
the corpuscle and the cavity in its nucleus ;" lastly, the disc is regenerated
by fissiparous divisions. These discs are also denominated 4 " primitive
discs," " foundations of future cells." The " parent cells " he conceives
to be made up of an assemblage of these discs. Again, Dr. Barry states,
" The nuclei of the blood corpuscles furnish themselves with cilia, re-
volve, and perform locomotion ; " " the primitive discs exhibit an in-
herent contractile power." And of the corpuscles themselves, he remarks,
" Molecular motions are discernible within the corpuscles of the blood," — -
" changes of form are observed under peculiar circumstances in the cor-
puscles of the blood." These are, however, only the beginning of wonders
related. Dr. Barry elsewhere goes on to observe : " In the mature blood
corpuscle (red-blood disc), there is often to be seen a flat filament or band
already formed within the corpuscle. In Mammalia, including man, this
filament is frequently annular; sometimes the ring is divided at a certain
part, and sometimes one extremity overlaps the other. In birds and am-
phibia the filament is of such length as to be coiled. This filament is
formed of the discs contained within the blood corpuscle. . . " The fila-
ment thus formed within the blood corpuscle has a structure which is very
remarkable. It is not only flat, but deeply grooved on both surfaces,'*
in an oblique manner. " It is deserving of notice," continues Dr. Barry,
" that in the first place, portions of coagulum of blood sometimes consist of
filaments having a structure identical with that of the filaments formed
within the blood corpuscle ; secondly, that in the coagulum I have noticed
the ring formed in the blood corpuscle of man, and the coil formed
in that of birds and reptiles, unwinding themselves into the straight and
often parallel filaments of the coagulum, changes which may be seen also
taking place in blood placed under the microscope before coagulation ;
thirdly, that I have noticed similar coils strewn through the field of
view when examining various tissues, the coils here also appearing to be
altered blood corpuscles and unwinding ; lastly, that filaments having the
same structure as the foregoing are to be met with apparently in every

D

34 ORGANISED FLUIDS,

which corresponds with the blood disc of the mammiferous
vertebrata, viz. the outer or capsular portion of it, the
nucleus which alone exists in the blood corpuscles of birds,
fishes, and reptiles, being entirely destitute of colouring
matter.

The colour of the blood, it has long been believed, is inti-
mately connected with the presence of iron in the blood cor-
puscles : from the fact, however, that iron exists in the chyle*,
and in the colourless blood of certain animals f , it is clear

tissue of the body." These filaments Dr. Barry conceives finally to con-
stitute " fibre," whenever this elementary structure is encountered.

These multiplied and extraordinary observations of Dr. Barry, it is
now necessary to observe, remain unconfirmed in all the most essential
particulars up to the present time. Shortly after their promulgation, Dr.
Griffiths \ and Mr. Wharton Jones 2, objected to the statement of Dr.
Barry, that there exists in the blood corpuscle a primordial fibre, observ-
ing that the appearances relied upon were due to decomposition. In
connection with the subject of fibre in the blood globules, the analogy
referred to by Dr. Will shire 3, between a dark line observed in the starch
vesicle, and Dr. Barry's alleged fibre, may be noticed as well as the
affirmations of Dr. Carpenter 4, that Dr. Barry had shown him, amongst
corpuscles of the blood of the newt, preserved in its own serum, many of
a flask-like figure, and which might be compared to a pair of bellows, and
the projecting portion of which appeared to Dr. Carpenter to be a filament
having a much higher refracting power than the general substance of the
corpuscle. Dr. Barry also showed Dr. Carpenter, in blood preserved in
corrosive sublimate, a corpuscle which was evidently destitute of the
ordinary nucleus, and which contained what appeared to be a filament,
presenting transverse oblique markings which resembled those of the
fibrillse of a muscle. The observations of Dr. Barry, and the confirm-
atory statements of Dr. Carpenter, will at least be possessed of historical
interest, if any real and intrinsic importance be denied to them. The
views of Dr. Barry are given at length in the Philosophical Transactions
for 1840—1843.

* See article " Lymphatic System, " by Mr. Lane, Encyclopaedia of
Anatomy and Physiology, April, 1841.

f " The Blood Corpuscle considered in its different Phases of Dcvelope-
ment in the Animal Series, by J. W. Jones, F.R.S. Transactions of the
Royal Society, Part II. for 1846.

1 Annals of Natural History. February, 1843.

2 Transactions of the Royal Society, December, 1842.

3 Annals of Natural History, 1843.

4 Annals of Natural History, 1842.

THE BLOOD. 35

that the mere presence of iron is not in itself sufficient to
account for the colour of the blood ; this depends most pro-
bably upon the state of combination of the iron in the blood.
Liebig states, as will be shown immediately, that the iron
in the blood exists in the varying conditions of peroxide,
protoxide, and carbonate of the protoxide of iron.

USES OF THE RED CORPUSCLES.

In connexion ivith Respiration. — Observation has taught
us the fact that the colour of the blood changes considerably
according as it is exposed to the influence of oxygen and car-
bonic acid gases, it becoming bright red under the influence
of the former, and dark red, almost black, under that of the
latter gas.

Now the microscope has revealed to us the additional fact
that the colouring matter of the blood resides within the red
corpuscles ; and hence we are led to infer that the changes of
colour alluded to are accompanied by alterations in the con-
dition of the colouring matter contained in those corpuscles.

Further, the alterations of colour which have been men-
tioned take place not only in blood withdrawn from the
system, but also in that which still circulates in the living
body, the vital fluid being exposed in the lungs to the in-
fluence of the oxygen contained in the atmosphere, and to
carbonic acid in the capillary system of vessels.

But it is not merely a change of colour which the blood
undergoes, or rather the coloured blood corpuscles undergo,
on exposure to either of the gases particularised, but they
also experience at the same time, as might easily be inferred,
a positive change of condition, a portion of one or other of
the gases to which the blood corpuscles are exposed being
imbibed by them.

That it is really the red corpuscles which absorb the oxygen,
or the carbonic acid, as the case may be, admits of demon-
stration, and is proved by the fact that these gases lose but
little volume when placed in contact with the liquor sa.nguims,
or serum of the blood.

b 2

36 ORGANISED FLUIDS.

It is clear, then, that the coloured corpuscles arc the seat
in which these changes occur. Again, from the fact that the
blood becomes bright red or arterial on exposure to oxygen,
as in the lungs, and dark red or venous on being submitted
to the action of carbonic acid, as in the capillaries, it has
been inferred that they are first carriers of oxygen from the
lungs to all parts of the system, and second, vehicles for the
conveyance of carbon back again to the lungs.

This inference is correct as far as it goes, but it fails to
explain why the imbibition of oxygen or carbonic acid gases
should be accompanied by changes in the colour of the blood ;
and it also fails to show why those gases themselves should
be imbibed.

From the constant presence of iron in the coloured blood
corpuscles, it has been inferred that this is the base with
which the oxygen and the carbonic acid gases combine, but
the exact nature of the combinations thus formed it was re-
served for the illustrious Liebig to make known.

Liebig declares, that in arterial blood the iron is in the state
of a peroxide, and in venous blood in the condition of a car-
bonate of the protoxide.

To this conclusion Liebig has arrived by observing the
manner in which the above-mentioned compounds of iron
comport themselves when not in connexion with the blood,
but when exposed to the same influences as the blood itself is
subjected to.

Thus he says, " The compounds of the protoxide of iron
possess the property of depriving other oxidised compounds of
oxygen, while the compounds of peroxide of iron under other
circumstances give up oxygen with the greatest facility."

Again, " Hydrated peroxide of iron, in contact with organic
matters destitute of sulphur, is converted into carbonate of
the protoxide."

Lastly, (( Carbonate of protoxide of iron in contact with
water and oxygen is decomposed, all the carbonic acid is
given off, and by absorption of oxygen it passes into the
hydrated peroxide, and which may again be converted into
a compound of the protoxide."

THE BLOOD. 37

Now, the above described changes, which the compounds
of iron when exposed to the same influences as the blood
corpuscles are themselves submitted to, precisely correspond
with those alterations which it is known and ascertained
that the blood corpuscles do themselves experience, and
therefore there is every probability in favour of the strict
accuracy of Liebig's explanation of the chemical changes
which the blood corpuscles pass through during respiration
and circulation.

Thus it has been long known, that in the lungs the coloured
blood corpuscles give off carbonic acid and imbibe oxygen :
it has also been ascertained that during their circulation
they lose a portion of their oxygen and acquire carbon.

Venous blood, then, exposed to the air gives out carbonic
acid and absorbs oxygen, but arterial blood submitted to the
same influence gives out oxygen and acquires carbonic acid,
the seat of these changes being the red corpuscles.

It will be seen on reflection, that, according to the views
just propounded, the surplus amount of oxygen which exists
in the peroxide becomes disengaged in the reduction of
that oxide to the state of protoxide : during circulation
in the capillaries, this surplus is chiefly expended in the
elaboration of the different secretions which are continually
being formed in the various organs of the body.

Such is the corpuscular theory of respiration. Hereafter
we shall have to speak of a corpuscular theory of nutrition
growth and secretion.

In connexion with Secretion. — It is very probable that the
use of the red corpuscles is not limited to the mere office of
carrying oxygen from the lungs to be distributed to all parts
of the system, and of carbon back again to the lungs to be
eliminated, but that they have an ulterior and additional
function to discharge. Thus some observers suppose that
they exert some influence over the constitution of the blood
itself, elaborating from the materials continually thrown
into it by the thoracic duct a further quantity of fibrin. There
is more reason to believe, however, that it is the white
corpuscles which are principally concerned in this process of

38 ORGANISED FLUIDS.

elaboration, seeing that their structure agrees with that
which is generally possessed by true secreting cells. I
therefore myself would be inclined to attribute to the red
corpuscles but little influence over the constitution of the
blood.

It may be stated that both Wagner * and Henlc are of
opinion that the red corpuscles are connected with secretion,
and the latter, in his " General Anatomy/' calls them
" swimming glandular cells."

Effects of Re-agents.

The blood globules arc much modified by the application
of numerous re-agents, and which, therefore, may be em-
ployed with advantage in their investigation.

Serum. — It has already been observed, that, in the serum of
the blood, their natural element, the globules preserve un-
altered, for a time, their normal form.

Water. — The application of water causes the globules
almost immediately to lose their flattened and discoidal
character, the depressions on their surface are effaced, and
they become spherical. This change in the form of the
corpuscles is necessarily accompanied by a diminution of their
size. (See Plate I. fig. 3.)

Spirits of Wine, ^Ether, Creosote. — The same results follow
the use of a variety of other liquids, as spirits of wine, aether
and creosote. These agents however, in addition, render the
globules exceedingly diaphanous, so much so indeed as that
they are often with difficulty to be discovered. In the globules
rendered thus transparent, no traces of granular contents can
be detected.

Acetic acid. — This preparation first deprives the globules
of their colouring matter, thus rendering them exceedingly
transparent, and subsequently dissolves the human blood
corpuscle, without residue, but not that of the frog, &c., the
nucleus of which remains entire. (See Plate II. fig. 5.)

* Physiology, by Willis, part ii. p. 448.

THE BLOOD. 39

Ammonia. — This alkali acts in a similar manner.

Nitric Acid, Muriate of Soda. — These re-agents contract
the globules, and render their outlines more distinct.

Iodine. — This likewise renders the outlines more distinct,
without at the same time deforming and otherwise altering
the globules.

Corrosive Sublimate. — In a strong solution of this liquid,
the outlines of the globules are more defined, and the
globules may be preserved for examination for a considerable
length of time.

We shall next pass to the consideration of the white glo-
bules, and show in what particulars of form and structure
they differ from the red.

WHITE GLOBULES.

The white globules of the blood are by far less numerous
than the red ; they nevertheless are more abundant than a
superficial observer would suppose : this arises from the fact
that many of them are concealed from view on the field of
the microscope by the red globules, wrhich so greatly out-
number them. The white corpuscles differ from the red in
several particulars — in size, in colour, in form, in structure,
in their properties, and doubtless also in their uses.*

Size. — In man and the mammalia the white globules are
generally larger than the red : like those, also, their dimen-
sions vary very considerably in the blood of the same indi-
vidual abstracted at any given time, and even to an extent
still greater. Their average size, when contained in the
serum of the blood, may, however, be estimated at about the
sjYo" °f an inchf (see Plate I. Jig. 1.): when immersed in
water, however, they swell up, and increase very consider-
ably in size, in this liquid sometimes measuring the

* Spallanzani was the first to notice the existence of two forms of
globules in the blood of salamanders ; Muller verified their presence in
that of the frog, and M. Mandl detected them inoman and mammalia.

f Mr. Gulliver gives the -^^ of an inch as the average measurement
of the human colourless blood corpuscle.

E

40 ORGANISED FLUIDS.

of an inch. (See Plate I. fig. 6.) In the blood of reptiles,
especially in that of the frog, a contrary relation between the
size of the red and white globules exists ; the latter in these,
instead of being larger than the red corpuscles, are two or
even three times smaller. This fact it is important to bear
in mind in considering the question of the transformation of
the white globules into red.

Form* — Instead of being of a flattened and disc-like form,
as are the red globules, the shape of the white corpuscle,
when free, is in all classes of the animal kingdom globular.
This particular likewise throws much light upon the disputed
point as to whether the white globules become ultimately
converted into red corpuscles, and which we shall have to
treat of more fully hereafter.

Like the red corpuscles, however, although to a less re-
markable extent, the white globules, when subject to pressure,
undergo a change of form : this change is frequently well
seen when viewing the circulation of the blood in the
capillaries, the white corpuscles often becoming compressed
between the walls of the vessels and the current of red blood
discs, and by which compression they are made to assume
elongated and oval forms ; like the red corpuscles, also, they
immediately regain their normal form, the pressure being
removed.

Structure. — In almost every relation which can be named,
the white globules would appear to be the antagonists of the
red ; for, instead of being of a homogeneous texture, they are
of a granular structure throughout, each full-sized white
globule being constituted of not less than from twenty to
thirty distinct granules, the presence of which imparts to it a
somewhat broken outline: these granules are often seen,
especially after the addition of water, and some other re-
agents, to be in a state of the greatest activity in the interior
of the corpuscles. It is only in the blood globule of mam-
malia, however, that we find this antagonism to prevail.
The blood corpuscle of the frog, and doubtless of other rep-
tiles, as well as birds and fishes, is assuredly a compound
structure, the investing or transparent part of each being in

THE BLOOD. 41

no way, as regards structure, distinguishable from the sub-
stance of the human blood disc, and the nucleus also being
identical in composition, though not in origin, with the
white globules of the blood, not merely of mammalia, but
likewise of reptiles, birds, and fishes. (See Plate II. fig. 5.)
The form of the nucleus, in the frog, &c., corresponds with
that of the globule ; that is, it is elliptical (see Plate II.
fig. 2.): water, however, affects the nucleus, as first observed
by Mandl, in the same way as it acts upon the corpuscle
itself, rendering both perfectly spherical. (See Plate TL.figs.
3. and 4.) If to globules in this condition acetic acid be
added, the capsule will be dissolved, leaving intact the
nucleus, between which and a white globule I have not been
able to detect, although using an instrument of the very best
description, the slightest structural difference : a difference
does certainly exist, but it is one of size, and not of struc-
ture, the nucleus being three or four times smaller than a
white globule of ordinary dimensions. (See Plate \\.Jig. 5.,
and Plate II. fig. 1.) This identity of organisation between
the white globule and the nucleus of the blood disc of the
frog, furnishes the strongest evidence with which I am ac-
quainted of the convertibility of the white globules into red,
evidence which, nevertheless, I regard as wholly inadequate
to demonstrate the reality of the conversion.

Nucleus. — The white corpuscles, under some circum-
stances, would appear to be nucleated; thus nuclei are
evident in corpuscles which have been immersed in water, or
even in serum, for any length of time, although they are not
usually seen in those of that fluid immediately after its
abstraction from the system. I am inclined to regard their
formation as resulting partly from the operation of endos-
mosis, whereby a portion of the contents of each corpuscle
becomes condensed in the centre.

The nucleus occupies sometimes the entire of the interior
of the corpuscle, a narrow and colourless border, destitute of
granules, alone indicating the extent of the corpuscle ; gene-
rally, however, it is about the one thifd of its size, and is
more frequently excentric than centric. It is usually darker

E 2

42 ORGANISED FLUIDS.

than the rest of the corpuscle, and would appear to contain a
greater number of molecules. (See Plate \.fig. 6.) Some-
times it presents to the eye of the observer the appearance of
an aperture ; this appearance, although very striking, is most
probably fallacious.

Mr. Addison regards the nucleus presented by the white
corpuscles as primary, an opinion in which I concur.

Properties. — The white corpuscles of the blood differ not
less in their properties from the red than they do in form and
structure : thus acetic acid, which dissolves the latter, con-
tracts somewhat the former, and renders the contained
granules more distinct; in water the red globules become
globular and smaller in size, while the white increase con-
siderably in dimensions in the same liquid (see Plate I.
Jig. 6.), and finally burst in it, their molecular contents
escaping. In liquor potasses both the red and white cor-
puscles are destroyed and dissolved ; previous to which,
however, in the white globules, some interesting changes
are seen to take place; immediately on the application of
the alkali the molecules contained in their interior are ob-
served to be in active motion, and in a short time the cor-
puscles burst open, or explode, discharging numerous gra-
nules, amounting sometimes to thirty or forty ; and which,
together with the transparent matter of the corpuscles, finally
becomes dissolved. — "Frequently when the liquor potassae
is acting with diminished energy, the corpuscles give a
sudden jerk, and in a moment enlarge to double or three
times their former size, without losing their circular outline :
the molecules and granules within them are more widely
separated from each other, but not dispersed ; and they are
seen held together, or attached to the tunic of the corpuscle,
by delicate connecting filaments. This singular and in-
structive change does not, of course, last long; the alkali,
continuing its action, ruptures the tunic of the corpuscle, dis-
persing and dissolving its contents." — Addison.

When examined in the living capillary vessels they are
seen to manifest different properties to the red, and also to
have a very different distribution in those vessels. Thus the

THE BLOOD. 43

white corpuscles frequently adhere to the inner wall of the
capillaries, which the red rarely do ; and while the red glo-
bules, in circulating, occupy the centre of each vessel, the
white corpuscles are placed between this and the walls of the
vessel.

A difference may also be observed in the relative speed
with which the two kinds of corpuscles circulate, the red
flowing onwards with greater rapidity than the white. The
forces which determine the circulation in the vessels would
appear to act only on the red corpuscles, the motion of the
white globules being entirely of a secondary and indirect
character, it being communicated to them by the edge of the
current in the axis of which the red corpuscles move, in the
same way as the stones at the bottom of a stream are rolled
over and borne onwards by the superincumbent water.

The cause of the slower motion of the white corpuscles in
the capillaries may be thus explained. A greatly retarded
motion of the fluid circulating in any vessel or channel is
always observed towards the periphral border of the current.
This retardation would appear to arise from the resistance
which the circulating fluid encounters by coming in contact
with the walls of the vessel or sides of the channel through
which it flows.

In what way, however, is the difference in the position in
the vessels occupied by the red and white corpuscles to be
explained ? why do the former always circulate in the
axis of the vessel while the latter are constantly placed
outside this ? and what is the inference to be deduced from
this difference in their situation ?

The red corpuscles, as we know, are flattened discs, con-
stituted of an elastic and yielding material ; and the white, on
the contrary, are globular bodies of a more dense composition
and of but little elasticity : now it is very probable that the
peculiar form and properties possessed by the coloured cor-
puscles of the blood may result in such an adaptation and
arrangement of them, the one with the other, that a physical
impossibility is presented to their indiscriminate admixture and
circulation in the same vessel with the white corpuscles.

E 3

44 ORGANISED FLUIDS.

But there are other facts which will serve to explain the
difference of position : thus the red corpuscles have an attrac-
tion for each other, as is manifested on the field of the mi-
croscope by the formation of the strings of corpuscles already
referred to, where also it is seen that they have no such
affinity for the white corpuscles, which usually lie detached
and isolated from the red. On the other hand, however, the
white, as before stated, have an attraction for the walls of the
vessels through which they pass, and which is declared by
their frequent adhesion thereto.

The question may be asked, have these attractions any thing
to do with electric conditions ? All the inquiries which have
been undertaken with the view of proving that the blood is
possessed of electric properties have hitherto signally failed
to demonstrate the existence of any.

Lastly, what inference is to be deduced from the different
positions occupied by the two kinds of blood corpuscles, and
from the different rates of their circulation in the capil-
laries ?

The rapid passage of the red corpuscles through the capil-
laries, together with their central situation, would lead the
observer to infer that they had but little direct relation with
the parts outside those capillaries, that the office discharged by
them was one of distribution, whereas the slow progress of the
white corpuscles through the capillary vessels, as well as their
peripheral position, would lead to the conclusion that a close
relation existed between them and the parts adjacent and
external to the vessels. Now these deductions are precisely
those which other facts and observations tend to confirm and
establish, as we have already seen in reference to the red
corpuscles, and as we shall immediately proceed to show in
relation to the white globules.

While viewing the capillary circulation, it is easy to con-
vince oneself that no contraction of the parietes of the capil-
laries occurs, and that, therefore, the motion of the blood is
independent of any action of those vessels themselves, on
their contents.

THE BLOOD. 45

USES OF THE WHITE CORPUSCLES.

The uses of the white corpuscles have not as yet been
fully determined ; enough, however, of their nature has
been ascertained to show that they are closely connected
with the functions of Nutrition and Secretion. We shall
here invert the natural order in which the description of
these subjects should be entered upon, and speak first of
secretion.

Uses in connexion with Secretion. — It would appear that,
for the most part, secretions are formed in cells : the cor-
rectness of this statement is, in some degree, proved by the
fact that the lower classes of the vegetable kingdom are
entirely constituted of cellular tissue.

It is also further supported by the fact, that the essential
structure of all glands in the animal frame is that of cells.

It would appear, also, that the cells, entering into the
composition of a single organ, have the power of producing
more than one kind of secretion. This is witnessed in the
petals of many flowers, the cells of which frequently elaborate
fluids of several distinct colours.

There is much reason to believe, that the granules, which
are so constantly associated with the cells, are the active
agents engaged in the production of the secretion, the exact
constitution of these granules determining the character of
the secreted product.

Now, in the white corpuscles of the blood we have precisely
the same granular constitution which is seen to belong to
cells which are indisputably engaged in the process of secre-
tion.

From the observation of these and other facts Mr. Addison
has been led to entertain the opinion, that the white corpuscles
of the blood " are very highly organised cells, from which the
special tissues and the secretions are elaborated." * In continu-
ation of this subject, Mr. Addison goes on to remark, — " And

* Experimental Researches, Transactions 0f Prov. Med. and Surg.
Association, vol. xii. p. 260.

K 4

46 ORGANISED FLUIDS.

it appears that the renovation of these tissues and secretions
from the blood does not take place by the cells discharging
their contents into the general mass of the circulating current,
to be separated therefrom by some peculiar transcendental
and purely hypothetical selective process of exudation,
through a structureless and transparent tissue, but by being
themselves attached to, incorporated with, and performing
their special function in the structure."

Thus Mr. Addison conceives that the fibrillating liquor
sanguinis is formed and elaborated in the white corpuscles of
the blood, and that it never exists in that fluid in a free state,
and that its presence in the crassamentum, and especially in
that part of it which constitutes the buffy coat, arises from
the rupture and destruction of the white corpuscles and the
escape of their contents. This opinion he supports by a
series of ingenious experiments, one of which may here be
referred to. The tenacious property belonging to mucus is
well known, in which respect, as well as in the smaller number
of globules, similar to the white corpuscles of the blood, con-
tained in it, it differs mainly from pus. Now, by the addition
of a drop of liquor potasses to a little pus, which was pre-
viously white and opaque, and in which the presence of a
considerable number of white corpuscles was ascertained by
means of the microscope, its appearance underwent a complete
change, the pus became transparent and tenacious, presenting
precisely the characters of mucus. The fluid being again
examined microscopically, it was found that most of the
globules were ruptured and dissolved, and that the liquid
portion of it fibrillated in the same way as that of mucus,
and that of the liquor sanguinis ; from this and other ana-
logous experiments Mr. Addison formed the conclusion, that
the fibrillating liquor sanguinis was derived from the white
corpuscles, and that it does not exist in the blood in a free
condition.

According to Mr. Addison, the secretions, " milk, mucus,
and bile, are the visible fluid results of the final dissolution
of the cells." Hence, therefore, a secretion is the result of
the last stage of the process of nutrition. And, again, " If,

THE BLOOD. 47

therefore, the colourless blood corpuscles be termed " parent
cells," they must be considered as pregnant with the embryo
materials of the tissues and secretions, and not with " young
blood cells."

It is scarcely necessary to observe that these highly in-
genious views of Mr. Addison are by no means established.
That the cells of glands and their contained granules are inti-
mately connected with secretion there are many facts to prove ;
but that the white corpuscles of the blood are, in the animal
economy, the special organs of secretion, and also that the
secretions said to be elaborated by them, escape from them,
not by transudation through their membranes, but are set free
by the entire and final dissolution of the corpuscles, are
views which cannot be safely adopted until much additional
evidence is adduced in support of them.

The opinion entertained by Dr. Barry, that the colourless
corpuscles are " parent cells," seems to me to be purely
hypothetical.

Let us now bestow a few reflections upon Nutrition.

Uses in connexion with Nutrition. — That the white cor-
puscles are concerned in the process of nutrition, there
is more evidence to show than there is in favour of their
connexion with that of secretion. The question to be
solved, however, is, in what way do these corpuscles ad-
minister to nutrition? do they contribute to nutrition
and growth, by their direct apposition to and incorporation
with the different tissues of organs ? This is the opinion of
Mr. Addison, who says of them, that they are the " founda-
tions of the tissues and the special secreting cells, the link
between the blood and the more solid structures, the unity
from which the pluralities arise."

Dr. Martin Barry also adopts the notion that tissues are
formed by the direct apposition of the blood corpuscles. Dr.
Barry makes no exact distinction between the red and the
colourless globules ; but from the fact of his calling the latter
" parent cells " filled with " young blood discs," it would
appear that he considered that the red corpuscles gave origin to
the different structures of the body by their direct union and

48 ORGANISED FLUIDS.

incorporation with each other. This view is far less tenable
than that of Mr. Addison, and neither is supported by a
sufficient number of facts to render its accuracy any thing
but exceedingly problematical.

That the white corpuscles of the blood are engaged in the
process of nutrition is proved by the fact, that they are found
in increased quantities in vessels which are actively adminis-
tering to that function. This accumulation is witnessed also
in the capillary vessels of any parts which are subjected to
irritation of any sort, and in which, as a consequence of that
irritation, there is augmented action.

The gradual collection of the white corpuscles of the blood
in the capillary vascular network, may be seen to the
greatest possible advantage in the tongue of the frog, as also
in the web of the foot of that conveniently formed creature,
as the result of continued exposure of the parts to the action
of air.*

But it is not alone the aggregation of the colourless
corpuscles that may be seen in the minute vessels ; their
escape from those vessels may likewise be determined by a
prolonged examination of them. If, after the continuance
of this congested condition of the vessels for twenty-four or
thirty-six hours, they are again examined, it will be obvious
that certain of the corpuscles have become entangled in the
fibres which form the walls of the vessels, and that certain
others have altogether passed the boundaries of the vessels,
and now lie external to them.

Again, it is asserted, that the epithelial cells are derived
from the white corpuscles of the blood. If this be correct, it
would appear that the escape of these corpuscles is a perfectly
normal and natural occurrence.

* Mr. Addison states that, in order to insure a satisfactory exhibi-
tion of this important and curious phenomenon, the parts should be
irritated in some manner, as by immersion for a minute or two in warm
water at a temperature of 95° Fahrenheit, or by permitting a few
crystals of common salt to dissolve upon it. These methods I have tried,
and have found that they have usually resulted in the entire cessation of
the circulation in the capillaries, and this has been also the case even
when a weak solution of salt in water has been applied.

THE BLOOD. 49

Thus far, then, the endeavour to prove the transformation
of the colourless corpuscles of the blood into tissue cells,
would appear to be successful ; but it is here the chain of
evidence breaks ;. and beyond the fact which is by no means
established, of their constituting epithelial cells, we have no
further proof to adduce of their structural incorporation with
the living tissues. Of this occurrence it would, of course,
be difficult to procure satisfactory demonstration, on account
of the opacity of the parts on which our examination would
have to be conducted. It may be remarked, however, that,
if founded in fact, we should expect to find a greater
correspondence in the size and form, &c., of the elementary
tissues, with that of the corpuscles from which, according
to some observers, those tissues are derived. *

The corpuscular theory of nutrition, then, proposed by Mr.
Addison, in the present state of our knowledge can only be
sustained by having recourse to a certain amount of theo-
retical reasoning or to particular assumptions.

The fact, however, still remains to us, that the white
corpuscles are concerned in nutrition, although the precise
manner in which they are so is still open to investigation,
and this fact is strengthened and confirmed by the phenomena
of disease. Thus, there is much evidence to show that,
wherever nutrition is impeded, the colourless corpuscles
accumulate in increased quantities in the vessels ; and it is
by this accumulation, also, that we are enabled to account for
the critical abscesses and discharges which characterise some
affections, and to recognise the importance which ought to
be attached to their occurrence.

That the colourless corpuscles are really present in in-
creased numbers in the blood, in disease, is attested by the
evidence of numerous observers : thus, Gulliver f, Davy J, and

* The cells of the liver and spleen resemble closely in appearance
the white corpuscles of the blood : between them, however, well-marked
differences exist, so that it is by no means to be inferred that the former
are derived directly from the latter. t0

f Appendix to Gerber's General Anatomy, p. 20.

I Researches, Phys. and Anat. vol. ii. p. 212.

50 ORGANISED FLUIDS,

Ancell*, have observed them in unusual quantities in in-
flammatory affections, and especially in such as are attended
with suppuration. Mr. Siddall and Mr. Gulliver have re-
peatedly observed them in vast numbers in the horse, especially
when this animal has been suffering from influenza. Donne
has likewise recognised their presence in increased quantities
in disease ; and Mr. Addison finds them to abound in the
hard and red bases of boils and pimples, and in the skin in
scarlatina and in most cutaneous affections.

Several processes have been pointed out by which the
white globules may be separated from the red, and thus be
brought in a manner more satisfactory under view. 1st.
Acetic acid dissolves the red corpuscles, leaving the white
almost unchanged. 2nd. A drop of water floated gently
across a piece of glass, on which a small quantity of blood
has been placed, will remove the red corpuscles, the white
remaining adherent to the surface of the glass. This
ingenious method was, I believe, first indicated by Mandl.
3rd. The third process depends for its success upon the de-
fibrination of the blood by whipping, and which has already
been alluded to. If blood thus defibrinated be set aside for
a time, the red globules will subside to the bottom of the
containing vessel, forming one stratum, and the serum will
float upon the top, constituting a second layer; but between
these two layers a third exists ; this is very thin, and is
formed by the white globules, which may be reached after
the removal of the serum by means of a siphon, f Donne
points out this method in his excellent " Cours de Micro-
scopie." 4th. A fourth means of procuring the white globules
is described by Mr. Addison. If a portion of fluid fibrin be
removed from beneath the pellicle which is first formed over
the clot, it will be found to contain numerous white globules.

* Lectures in the Lancet, 1839-40, vol. ii. p. 777.

f The position occupied in this case by the white corpuscles shows that
they are of lighter specific gravity than the red, a reference to which fact
will also account for their presence, in such quantities, in the buffy coat of
the blood, and will likewise explain the reason why they first come into
focus when mixed with the red globules in a drop of water.

THE BLOOD. 51

The observer, having satisfied himself of the accuracy of
the various facts brought under his notice, in the next place
will be prepared to enter into the important questions as to
the origin and destination of the globules of the blood. We
will consider first the origin of the white globules.

ORIGIN OF THE GLOBULES OF THE BLOOD.

The origin and end of the blood globules ! Whence do
they come, and whither do they go ? These are questions
of the highest importance ; and it could be wished that the
replies to them were of a more satisfactory and definite nature
than those which we are about to make will, it is feared, be
considered.

Origin of the White Globules. — Various opinions have been
entertained in reference to the nature and origin of the white
corpuscles of the blood, the principal of which we will now
proceed to notice.

One of the earliest notions formed respecting the white
corpuscles was that of Hew son, who believed that they were
to be considered as the nuclei of the red blood corpuscles, and
hence he denominated them " central particles : " to this con-
clusion Hewson was doubtless led by observing the great and
remarkable resemblance which exists between the nuclei of
the blood globules of certain animals and the white corpuscles
themselves.

Two facts, however, are known, which satisfactorily prove
that the denomination of central particles is not applicable to
the white corpuscles, and that they do not form the nuclei of
the red blood discs : the first of these is, that no nuclei exist
in the true blood globules of the entire class of mammalia in
which white corpuscles are abundantly encountered, and the
second is the great difference in size observed between the
nuclei and the white corpuscles in those animals in which the
two organisms exist together in the blood.

An opinion somewhat similar to the above has been held
by some observers, viz. that the white0 corpuscles are to be
regarded as the " escaped nuclei " of the red blood corpuscles.
The facts adduced to disprove the former notion respecting

52 ORGANISED FLUIDS.

them are likewise sufficient to show the fallacy of that just
referred to.

By Dr. Martin Barry the white corpuscles are considered
to be the last stage of the development of the red blood disc,
and he has assigned to them the designation of "parent cells"
under the impression that the granules, of which many are
contained in each corpuscle, become developed into new
blood discs ; this idea of Dr. Barry is purely hypothetical,
and its accuracy is but little probable.

Mr. Addison also believes that the white corpuscles repre-
sent an advanced condition of the growth of the red blood
disc, but he differs from Dr. Barry, however, in not con-
sidering them to be parent cells, filled with young embryos,
designating the white corpuscles " tissue cells," under the
belief that they become incorporated with, and constitute an
integral portion of the solid structures of our framework.
The value of this theory has already been discussed.

Mandl denominates the white corpuscles "fibrinous glo-
bules" and he conceives that the nuclei, which he states be-
long to all red corpuscles of the blood, as well as the white
globules, are not primary formations, but secondary, — that
these structures do not exist in the blood while circulating
within the body, but that they are formed after its abstraction
therefrom ; and M. Mandl further states, that the steps of the
formation of the white globules may be witnessed on the port
object of the microscope. That this view is incorrect not the
shadow of doubt can be entertained. The regular form and
size of the white globules, their presence in the blood the
moment after their abstraction from the system, but'especially
the fact that they may be seen in vast quantities in that fluid
while still circulating in the capillaries, all negative the idea
of the formation of the white globules out of the system, in
obedience to a mere physical law.

Mr. Wharton Jones, in a recent communication made to
the Royal Society, has bestowed upon the white corpuscles
the appellation of " granule cells" and that gentleman con-
siders them to represent an early stage in the development of
the red blood globule. The peculiar views entertained by

THE BLOOD. 53

Mr. Jones will, however, be referred to more fully under the
head of the origin of the red blood disc.

The white corpuscles are also synonymous with the " ex-
udation corpuscles " of many writers, and especially of Gerber,
who has under this denomination assigned to them a false
value ; the presence of the white corpuscles in the plastic
fluid of exudations being rather accidental than essential.

We come now to refer to the opinion entertained respect-
ing the white corpuscles by Miiller, who denominated them
(< lymph corpuscles" conceiving them to be identical with the
granular corpuscles encountered in the lymphatic fluid. Of
all the opinions and theories of the nature of the white cor-
puscles alluded to, that of Miiller is probably the only correct
one : Miiller, however, was not acquainted with their exist-
ence in the blood of mammalia, but merely in that of frogs
and other analogous animals.

The opinion that the white corpuscles are red blood glo-
bules in process of formation is one which is maintained by
many observers, and nevertheless I regard it as erroneous.
In the truth of this view Wagner, Baly, Gulliver, Professor
H. Nasse, and above all Donne, are believers. From the
excellent work of the latter writer I introduce the following
remarks in relation to this point : —

" About two hours after injection (with milk), rabbits, dogs,
and birds have been opened. I have collected the blood in
the different organs, in the lungs, the liver, and the spleen ;
everywhere I have found the blood in the state in which I
have described it above, containing a certain number of
white globules in all stages of formation, and of red globules
more or less perfect : invariably the spleen has presented to
me special circumstances so established and so constant that
it behoves me to mention them, and especially since they
may throw light, at length, upon the true functions of this
organ, so long and so vainly sought. I do not dare flatter
myself with having completely resolved this problem, and it
is but with reserve that I express myself in this particular.

" The blood contained in the large'Vessels of the spleen
offers nothing very remarkable ; but, in expressing that

54 ORGANISED FLUIDS.

which is enclosed and, as it were, combined with the tissue
of this organ, one finds in it a composition well worthy of
fixing the attention. In a word, this blood is so rich in
white globules, that their number approaches nearly to that
of the perfect blood globules ; but, further, the white globules
which are there, present in as evident a manner all the de-
grees of formation and development, and the examination of
this blood does not appear to me to leave any doubt upon
the transition which I have pointed out above of white glo-
bules to red corpuscles, and upon the successive phases through
which the white globules pass to arrive at the state of perfect
blood globules. This phenomenon is, above all, striking after
injections of milk, and during the work which is accomplished
in the space of four and twenty hours, of the transformation
of the immense quantity of milk globules into blood globules.
One cannot believe that this is not really the point —
the laboratory, if one may so speak — in which this trans-
mutation is effected, and that the spleen is not the true
organ of this important function. But I know how like
facts, and how the theory which results from them, have
need to be confirmed by the researches of other observers, to
be definitively adopted with confidence."*

In answer to these observations of M. Donne I would
remark, first, that I have never seen the different stages of
formation of the white corpuscles, and of transformation of
these into red, described by M. Donne, and, second, that I
believe that he has totally misinterpreted the appearances
presented by blood pressed out of the spleen. The cells or
corpuscles of which that organ is itself constituted so closely
resemble the white globules of the blood, that I feel assured
that M. Donne has failed to discriminate between the two,
and that many of his progressive stages of development are
to be referred to the splenic cells or corpuscles, numbers of
which are always contained in every drop of blood procured
from the spleen.

Having now noticed the various opinions held by different

* Cours cle Microscopic, pp. 99, 100.

THE BLOOD. 55

observers in reference to the nature of the white corpuscles,
we will next pass to the consideration of their origin or
mode of formation. The idea that the white corpuscles are
elaborated by the lymphatic glands has already been referred
to ; and, from the absence of these glands in the lower ovipa-
rous vertebrata, it is evident that they cannot be regarded as
essential to their formation.

It has been stated that, in addition to the white and red
globules, numerous smaller particles, termed molecules, exist
in the blood. The white globules, in all probability, derive
their origin from these molecules, a number of them going
to constitute a single white globule. This aggregation of
the molecules into masses, or globules, would appear to result
from the operation of a general law of the economy, under
the influence of which the globules unite with each other,
and become invested with a coating, or membrane, probably
of an albuminous nature.

Donne believes also that he has traced, by direct observa-
tion and experiment, the transformation of the minute oily
and fatty particles, found in the milk, into white globules.
He injected numerous animals, birds, reptiles, and mamma-
lia, with various proportions of milk, and, strange to say, the
creatures thus experimented upon experienced no injurious
effect beyond a momentary shock, with, however, the single
exception of the horse, to which the experiment proved fatal
in seven different cases. If, almost immediately after the
injection of the milk, a drop of blood be withdrawn from the
system at a distance from the point where the milk was intro-
duced, a number of the globules of the milk may be detected
quite unaltered, and which may be recognised by their ge-
neral appearance, their smaller size, and, lastly, by the action
of acetic acid, which dissolves the red globules, renders ap-
parent the granular texture of the white, but leaves untouched
the molecules of the milk. If the blood be again examined
at about the expiration of two hours, the smallest milk glo-
bules will be seen to have united themselves with each other
by threes and fours, and to have become enveloped, by
circulating in the blood, in an albuminous layer, which forms

F

50 ORGANISED FLUIDS.

around them a vesicle, analogous to that which surrounds the
white globules. The largest remain single, but are equally
enveloped in a like covering. These soon break up into
granules, in which state the milk globules bear a close re-
semblance to the white globules of the blood, from which,
finally, they are not to be distinguished. " The blood,"
Donne remarks, " then shows itself very rich in white glo-
bules ; but, little by little, these undergo modifications more
and more profound ; their internal molecules become effaced,
and dissolved in the interior of the vesicle, the globule is
depressed, and soon it presents a faint yellow colouration :
they yet resist better the action of water and acetic acid
than the fully formed blood globules, and it is by this that
they are still to be distinguished. At length, after twenty-
four hours, or, at latest, after forty-eight, matters have re-
turned to their normal state ; no more milk globules are to
be found in the blood, the proportion between the white
globules and the blood globules, between the imperfect and
the perfect globules, has returned to what it is ordinarily ;
in a word, the direct transformation of the milk globules
into blood globules is completed."

In the opinion that the milk globules are convertible into
the white globules of the blood Donne is probably correct,
although it must be an inquiry of much delicacy and nicety
to determine this point by direct observation. The evidence,
however, in favour of his latter position, viz. that the white
globules become ultimately converted into red corpuscles,
is much more defective, and the facts upon which he relies
to sustain this view are open to question, as we have already
seen.

The view, then, of the transformation of white corpuscles
into red, I consider to be erroneous, and that the white
corpuscles, as they differ from the red, in form, structure,
and chemical composition, so they also differ in origin ;
and that the two forms of corpuscles are in every respect
distinct, as well in function as in origin.

From the fact of the white corpuscles of the blood being
encountered in considerable quantities in the lymph and chyle,

THE BLOOD. 57

which is in truth blood in its primitive form, it is in those
fluids, doubtless, that they take their origin, and it is in them
that they are best studied.

Origin of the Red Globules. — It has already been shown that
Donne and others consider that the red globules are formed
out of the white, which they view as true blood globules which
have not reached the last degree of elaboration. Donne sustains
this opinion by reference to the following particulars : — First,
that amongst the red globules contained in a single drop of
blood, all are not affected to the same extent by the use of the
same re-agent; that some resist its influence for a much
longer period than others ; Secondly, he states, that he has
observed, in some true blood globules traces of a slight
punctuation, similar to that which is seen in the white cor-
puscles ; and, Thirdly, in certain white globules he has noticed
the compressed form common to the red corpuscles. From
the observation of these facts he draws the conclusion, that
the white globules are transformed into red blood discs.
The first particular alluded to, viz. that the same re-agent
does not affect equally all the red globules of the same blood,
is doubtless to some extent correct, and may be explained by
supposing that the red corpuscles are not all of the same age,
and therefore are of different degrees of consistence. The
remarks as to the granular texture of true blood corpuscles,
and the compressed form of certain white globules, it has
never happened to me to be able to verify in a single instance ;
and, for my own part, therefore, I am inclined to allow to
them but very little weight in determining the question of
the origin of the red corpuscles of the blood. To the views
of M. Donne on this point a high degree of plausibility and
ingenuity must certainly be accorded ; but, in considering this
question, not merely the doubtful and even debateable nature
of the evidence adduced by M. Donne must be taken into
consideration, but also the following fact, — viz., that no defi-
nite relation exists in the animal kingdom between the size
of the red and white globules compared together. In man,
and most mammalia, the white globules are larger than the
red (see Plate I. Jig. 1.) ; in most reptiles, and particularly

F 2

58 ORGANISED FLUIDS.

in the blood of the frog, they are very much smaller (see
Plate II. fig. 1.): from whence it would result that the
process adopted by nature for the conversion of the white
globules into red, would, in the two classes of the animal
creation cited, be of a character wholly different the one
from the other. In the first-mentioned the transmutation
would be a work of decrease ; in the second, of increase, or
superaddition ; and this supposition, I conceive, would be
tantamount to charging nature with the commission of a gross
inconsistency.

There are other observers, again, who believe in the for-
mation of the coloured blood corpuscles out of the colourless
ones, in a manner totally different from that described by
M. Donne.

Thus Mr. Jones, in a communication recently made to
tl^e Royal Society, and entitled " the Blood Corpuscle con-
sidered in its different Phases of Development in the Animal
Series," states that the blood corpuscle presents throughout the
animal kingdom at least two phases of development ; in the
first of these the corpuscle is granular, and in the second
nucleated: when in the former phase it is denominated
" granule blood cell" and in the latter " nucleated blood cell;"
the first condition, or that of granule blood cell, is synony-
mous with the colourless corpuscle of the blood.

But each of these two phases presents likewise two stages
in their growth or formation: thus the granule blood cell
may be either coarsely granular, or it may be finely granular;
and the nucleated blood cell may be either uncoloured or
coloured. The first three stages are encountered, according
to Mr. Jones, in the whole animal series, but not the fourth
stage, the coloured condition of the nucleated blood cell,
which is wanting in most of the Invertebrata, and in one of
the series of Vertebrate animals, a fish, the Branchiostoma lubri-
cum Costa ; in all the other divisions of the animal kingdom
it is present, as in the Oviparous Yertebrata and the Mam-
malia.

In the latter class, the Mammalia, a third phase is super-
added to the other two, that of a "free cceliform nucleus:"

THE BLOOD. 59

this appellation expresses the usual condition in which the
blood disc in the mammalia is encountered, and in which no
nucleus can be discovered.

This third phase Mr. Jones considers to be derived from the
nucleated blood cell in its second stage ; the " free cceliform
nucleus" being the escaped nucleus of the nucleated blood cell.

The facts by which this view is supported are, first, a
relation in size between the nucleus of the nucleated blood
cell and the ordinary blood disc, or " free coeliform nucleus,"
and second, the occurrence, which is, however, very rare, of
nucleated cells from which the nuclei themselves have escaped.

The "nucleated blood cell" Mr. Jones found abundantly
in the blood of an embryo ox, an inch and a quarter long;
very sparingly in that of the elephant and horse, and not at
all in the blood of the human subject: he encountered them,
however, freely in the chyle of man.

Such is a brief statement of the views of Mr. Jones in
reference to the blood corpuscle, and of the chief facts by
which those views are supported : without taking upon my-
self to pronounce upon them decidedly, I yet must confess
that they carry with them but little conviction to my mind,
and that the facts adduced to sustain them are open to
considerable discussion.

If the blood corpuscles of animals in general, and of the
mammalia in particular, pass through the successive phases
and stages described by Mr. Jones, how happens it, I would
ask, that in the blood of mammalia, and especially in that
of man, while we meet with so abundantly the first stage
of the first phase, that of granule blood corpuscle, viz. the
coarsely granular stage, and also the last phase indicated by
Mr. Jones, that of free coeliform nucleus, we do not fre-
quently encounter the intermediate stages and phase,
through which, according to Mr. Jones, the blood corpuscles
pass?^ To this question I do not think it easy to give a
satisfactory reply, consistent with the opinions of Mr. Jones.
The explanation which I would give of the absence of these
transition forms is, that they have no real existence.

According to Mr. Jones the nucleated blood cells of the

r 3

60 ORGANISED FLUIDS.

Oviparous Vertebrata are of a nature totally distinct from the
ordinary blood cells of the Mammalia, which have no nuclei,
but that the nuclei of the blood cells of the former are the
analogues of the latter; this opinion is scarcely consistent with
the difference of structure and chemical composition observed
between the two. Opinions very analogous to those of Mr.
Jones in reference to the nature of the blood corpuscles of
the mammalia, viz. that they are escaped nuclei, appear to
have been entertained by Mr. Gulliver from observations
made on the horse; this gentleman supposing that the
red corpuscle was the escaped nucleus of the white granular
corpuscle, while Mr. Jones conceives that the red blood disc
is the liberated nucleus of the same body, only in an ad-
vanced condition of its development, in the stage of coloured
nucleated blood cell.

To the appellations by which Mr. Jones designates two of
his phases of the development of the blood corpuscle an
exception may fairly be taken. The "granule blood cell"
is frequently nucleated, even while it still retains its granular
structure, and therefore the term selected by Mr. Jones to
indicate a condition of the blood corpuscle distinct from its
granular state, viz. that of nucleated blood cell, is inappropri-
ate, and calculated to lead to the inference that the granule
blood cell is not a nucleated body.

I reiterate then the opinion, that the white and red
globules of the blood are wholly distinct from each other,
— distinct in origin, in structure, and in function.

The strongest fact with which I am acquainted (but it is one
which is not employed by M. Donne), in favour of the trans-
mutation of white globules into red, is this, — viz. that the
nucleus which exists in the blood discs of the frog, and rep-
tiles in general, is of a granular structure, in all respects
similar to that of a white globule, with the differences only
of size and form, the nucleus being four or five times smaller
than a true white globule, and of an oval instead of a circular
outline. (See Plate II. fig. 5.) One of these differences, as
already stated, — viz. that of form, — is effaced by water, which
renders the nucleus circular (see Plate II. Jig. 4.), in which

THE BLOOD. 61

state the only distinction between it and a white corpuscle
which can be detected is the single one of size. (See Plate
II. Jiff. I.) This difference, however, is so great, and coupled
with the fact that no white globules have ever been detected
in the frog, putting on the characters of a true red blood cor-
puscle, that the opinion that the white globules are trans-
formed into red blood discs must again be abandoned. The
existence of a granular nucleus in the blood discs of reptiles,
&c. revives again the old notion, that the white globules are
the escaped nuclei ; that they are not so is proved by the
fact that no such nuclei exist in the true blood globules of
man and the mammalia, in the blood of which white cor-
puscles abound.* The blood discs, it has been observed,
first make their appearance in the chyle : any inquiries, there-
fore, instituted with the view of determining their origin and
development in man, would be more likely to prove successful
if directed to the rigorous examination of that fluid, f

In the last place, it remains to treat of the end or final
destination of the red globules of the blood.

* The following interesting remarks of Mr. Gulliver tend to confirm
somewhat the views of M. Donne : they are by no means conclusive
however : — " White globules about the same size as those in the blood of
man, and probably identical with the proper globules of chyle and lymph,
are common in the blood of birds, and particularly abundant after a full
meal in the vultures and other rapacious families. Some of the red discs,
too, instead of the oval form, are often nearly or quite circular in figure.
Hence the blood of these birds would appear especially favourable to ob-
serve any changes in the white globules ; and it seemed highly probable,
that these might be transformed into the blood discs in the manner men-
tioned by Dr. Baly ; but although I made many observations with the
view of determining this question, nothing but negative results were
obtained." (Appendix to Gerbers General Anatomy, p. 24.) This ob-
servation is satisfactory in one respect, viz. that it shows clearly the
connection, which has already been dwelt upon, of the white corpuscles
with nutrition.

f For further observations on the development of the red blood disc,
see the remarks on the circulation in the embryo of the fowl.

i- 4

62 ORGANISED FLUIDS.

THE END OR FINAL CONDITION OF THE RED GLOBULES.

Every where throughout the solid constituents of the animal
organisation cellular tissue abounds; it forms the basis of
every texture and organ of the body. It is, therefore, scarcely
to be wondered at that the opinion should have been adopted,
that the globules which exist in such vast numbers in the
blood, were to be regarded as the primary and even parent
cells, out of which all the solid structures of our frame took
their origin.* This theory, to the mind of the earlier micro -
grapher, must have appeared very rational and seductive ;
and so great, indeed, is the plausibility with which, even in the
present day, it is frequently invested, that it is still able to
claim a few adherents.

If we regard with the utmost patience and attention the
beautiful spectacle of the capillary circulation in any of the
more transparent parts of animals, but especially in the
tongue of the frog, we shall in vain look for the escape from
their containing vessels of even a single red blood corpuscle,
independent of a rupture of those vessels. In a normal state,
therefore, the blood globules are never free, but are always
enclosed in their own proper receptacles.

A communication, however, between the fluid contents of

* Amongst those who regard the blood corpuscles as cells, may
be named Schwann, Valentin, Addison, Remak, and Barry. Schwann
describes the blood globule as a " nucleated cell," whilst Valentin con-
siders it to be a nucleus, and that which is usually held to be
a nucleus he regards as a nucleolus. Remak states, that he has wit-
nessed the development of the globules as parent cells, not within the
blood, but within the cells which line the walls of the blood vessels and
lymphatics. The views of Addison are confined chiefly to the white
globules, which he conceives to be the fully developed nuclei of the red
blood corpuscles, and which he believes to be transformed into epithelial
cells, &c. &c. Dr. Barry goes further than this ; for he states that every
structure which he has examined, arises out of the blood corpuscle, " the
crystalline lens itself, and even the spermatozoon and the ovum." The
opinions entertained by Gerber seem to be of a nature somewhat similar
to the foregoing. It is difficult to understand, however, what his exact
sentiments are : they, at all events, go to the extent of supposing that all
the solid structures of the body are derived from pre-existing germs, con-
tained in the chyle and blood.

THE BLOOD. 63

the blood-vessels and the tissues lying external and adjacent
to them, is doubtless established, through the operation of the
principle of exosmosis, whereby a slow exudation of the fluid
fibrin of the blood is perpetually going forward. Now it is
the opinion of most of the German physiologists, and it is
the view best supported by facts, that this fluid fibrin is to
be regarded as the true blastema, out of which all the dif-
ferent elementary tissues and structures of the body proceed,
and this not by any power inherent in itself, it being, as
respects the final form which it is made to assume, totally
inert and indifferent, and which form is impressed upon it by
a vis insita, or peculiar power and faculty belonging to each
organ and structure of the animal fabric.

While the fibrin circulates in the blood it retains its fluid
form ; soon after the cessation of the circulation, and whether
within or without the system, it passes from the fluid state
to the condition of a solid: now, on the principle of endosmosis,
which has to be so often referred to in the explanation of
numerous phenomena, in the solidifying power of the fibrin,
and in the vis insita of the different tissues, we recognise the
chief and fundamental causes which regulate nutrition,
growth, and secretion.

It would thus appear that the globules of the blood (the
red globules are more particularly alluded to) are not to be
regarded as either cytoblasts or primary cells, forming by
direct apposition the solids of the body, and that therefore
they do not express the last degree of elaboration of which
the fibrin of the blood is susceptible.

Again, then, we have to ask ourselves the question, what
is the end, or final condition, of the red blood globules ? Direct
observation is wanting to aid us in the solution of this difficult
inquiry, which, however, admits of an indirect reply being
given : we have seen that no means of egress from the blood-
vessels is, under ordinary circumstances, permitted to the red
blood globules, and therefore we are driven to the conclusion
that, having performed the important function to which we
have already alluded, viz. that of carriers of oxygen from the
lungs throughout the system, and of carbon from the latter

64 ORGANISED FLUIDS.

back again to the lungs, they become dissolved, increasing by
their dissolution the amount of fluid fibrin circulating in the
blood, and which is deemed to be the true blastema.

MOLECULES OF THE BLOOD.

In addition to the red and the white globules, there exists,
as already mentioned, in the blood a third description of
solid constituent, the " molecules : " these are synonymous
with the " basin-shaped " granules of Yogel, the " globulins "
of Donne, and the " primary discs " of Martin Barry.

The term molecule, or granule, is well suited to designate
these particles: for either appellation will serve to convey some
idea of their exceeding minuteness, and which is computed
rarely to exceed the ^ ~ n of an inch. They occur in great
quantities in the blood, either scattered singly throughout it
or agglomerated into small and irregularly shaped masses.
(See Plate I.jfig. 6.) The molecules are usually regarded as
the elements out of which the blood corpuscles are formed :
on this point, however, direct observations are still wanting.
It is more probable that the white globules are developed
out of them than the red, and this simply by their union or
aggregation.*

PECULIAR CONCENTRIC CORPUSCLES.

Besides the red and the white globules and the molecules,
which we have described as present in the blood, a fourth
species of solid corpuscle has been observed to occur in its
fibrinous constituent. These corpuscles have been repeatedly

* Since the above few lines were written on the " molecules " of the
blood, I have repeatedly remarked, that in blood, on its first ab-
straction from the system, but few molecules were present, while in that
which has been withdrawn from the body for some time, they have always
abounded. This observation has led me strongly to suspect, that the
molecules do not exist in the blood in a free state, but that wherever and
whenever they are encountered, save only in the chyle, they are to be
considered as derived from the rupture and destruction of the white
corpuscles.

THE BLOOD. 65

encountered by Mr. Gulliver * in clots of fibrin in man and
other mammalia, and are alike to be found in them, whether
the clots are formed in the body after death, or in blood
abstracted from the system during life.

These corpuscles, of a very peculiar structure, as will be
seen hereafter, Mr. Gulliver has described and figured with
extreme accuracy ; and he has styled them " organic germs,"
" primary or nucleated cells," and as capable of further deve-
lopment if placed in circumstances favourable to their growth.
Mr. Gulliver, however, would appear to have been quite
undecided as to their real nature, and whether they were not
to be regarded as identical with the " fibrinous globules " of
Mandl.

These peculiar bodies I have myself met with in fibrinous
clots which were found in the heart after death ; and I have
no hesitation in asserting that they differ, in every essential
particular, from the fibrinous globules of Mandl, which are
identical with the colourless corpuscles of the blood.

The size of these corpuscles is subject to the greatest pos-
sible variation ; they are frequently smaller than the white
globules of the blood, but very generally three or four times
larger ; their form is also irregular, but inclining, in those
which I have examined, to the spherical. They consist of
two parts, of nuclei and envelopes : the nucleus is of an
irregular outline, and not usually well defined without the
aid of re-agents ; its bulk is about the one fourth or one fifth
of that of the entire corpuscle; the envelope, in all the
globules which have fallen under my observation, has been
compound, that is, made up of several vesicles concentrically
disposed, the one within the other. (See Plate TV. Jiff. 3.)

The appearance presented by these objects bears a close
resemblance to the vesicles of certain species of Algae, of the
genus Microcystis or H&matococcus, these being likewise each
comppsed of several concentrically arranged membranes or
vesicles.

Now, what is the opinion which ought to be entertained

* See translation of Gerbcr, p. 31., and Appendix, p. 16.

66 ORGANISED FLUIDS.

in reference to the nature of these corpuscles ? Do they
really constitute an integral portion of our organisation ? and
do they circulate in the living blood ? or are they formed in
it after death ? The opinion of Mr. Gulliver that they are
primary, or nucleated cells, has already been referred to :
my own impression as to them is, that they do not constitute
an integral portion of our frame ; and that, whether they exist
in the living blood and circulate in it, or are formed in the
clot subsequent to decease, they are to be regarded as extra-
neous formations,, probably of an entozoal character.

It does not appear that the envelopes of all the corpuscles
met with by Mr. Gulliver exhibited concentric stride, al-
though he describes some of them as possessing this striated
structure : Mr. Gulliver speaks also of cells three or four
times larger than the corpuscles, and capable of containing
the latter as nuclei. These I have not myself encountered.

The corpuscles are not usually scattered equally through-
out the fibrinous clot, but frequently occur in groups, parts
of each clot being altogether free from the corpuscles.

Acid re-agents, especially the sulphurous acid, will be
found useful in their examination.*

BLOOD GLOBULES OF REPTILES, FISHES, AND BIRDS.

The red globules of the blood of the reptile, the fish, and
the bird, have all certain characters in common with each
other, which serve to distinguish them from those of man
and the mammalia in general. The chief of these character-
istics are their form, their size, the presence of a nucleus,
and, lastly, their greater consistence. The compressed form
belongs to the red blood globules of all animals ; in the three
classes of reptiles, fishes, and birds, however, although the
globules possess this flattened figure, instead of being circular,
as in man and the mammalia, they are in outline elliptical ;

* Since writing the above description, I have met with these concentric
corpuscles in connexion with the thymus gland which had been allowed
to remain in water for a few hours.

THE BLOOD. 67

and, in place of having a central depression, this part of each
globule is slightly protuberant. This prominence is due to
the presence of a nucleus, which in the mammalia we have
seen to be absent.

The size of the red globules is as distinctive as their form,
it usually exceeding, in reptiles, three or four times that of the
majority of the blood corpuscles of mammalia. The blood
disc of the frog equals in length the TTV j of an inch, while
its transverse measurement is not less than the T^Vj °f
an inch ; no\v the corpuscle of the elephant, the largest known
amongst mammalia, reaches only the grW °^ an *ncn 'm
diameter.*

It has already been remarked that most of the animals
of the order Camelida are possessed of blood globules of an
elliptical form, constituting in this respect an exception in
the class to which they belong. These oval corpuscles
are, however, so small that they could not be readily con-
founded with the elliptical globules of the frog, &c. : they
therefore agree in size, as well as in the absence of a nucleus,
with the blood corpuscles of other mammalia,- although not in
form. While every possible care has failed in satisfactorily
demonstrating the presence of a nucleus in the blood of mam-
malia, not the slightest difficulty is experienced in detecting
it in that of the frog and most of the animals belonging to the
classes just mentioned, and therefore its presence is generally
recognised; although one excellent observer, M. Mandl, is
of opinion that its formation takes place subsequently to the
removal of the blood from the system : this idea is doubtless
erroneous, as we have seen to be the case with respect to the
white corpuscles of the blood, regarding which M. Mandl
entertained a similar notion. In blood corpuscles immersed
in their own serum, and examined immediately after their ab-
straction, the nucleus may be seen with a sufficient degree of

* The largest blood corpuscles hitherto discovered in the animal king-
dom are those of the Siren and Proteus. In the Siren, according to Mr.
Gulliver, the long diameter of the blood discs isothe 435th, and the short
the 800th part of an inch, while in the Proteus they are stated at about
the H50th part of an inch in length.

68 ORGANISED FLUIDS.

clearness to enable the observer to pronounce with confidence
upon its presence. After the lapse of a few minutes it becomes
much more apparent, so that its composition is easily to be
discerned : this arises, most probably, from the discharge of a
portion of the colouring matter of each globule. The form
of the nucleus is seen to correspond with that of the blood
corpuscle itself, and to be oval, presenting a granular struc-
ture precisely resembling that of the white globules of the
blood, from one of which it is only to be distinguished by its
much smaller size and oval form. (See Plate YL.Jlg. 2.)

Owing to the firmer texture and greater size of the blood
globules of the frog, their structure can be well studied, and
the effects of re-agents more easily determined.

In water, the red corpuscles lose their colour, and become
circular, and indeed globular, a change of form which the nu-
cleus is likewise seen to undergo. (See Plate TL.Jigs. 3 & 4.)
These alterations ensue almost immediately on the application
of the water: its continued action produces an effect still
more remarkable ; the nucleus, which at first occupied a central
position in the globule, is soon seen to become excentric, and
finally, rupturing the pseudo -membrane of the corpuscle,
escapes into the surrounding medium ; the nucleus and the
outer portion of each globule are then observed as two distinct
structures, lying side by side (see Plate II. Jig. 4.) ; the
latter is at length absorbed, and then nought remains but the
nucleus, which is, as already remarked, under the influence of
water rendered of a globular form, and which is in no way
distinguishable from a white corpuscle of the blood, save in
the single particular of size, the nucleus being several times
smaller than the globule.

Acetic acid dissolves, if strong almost immediately, the
outer tunic, without occasioning the prior extrusion of the
nucleus, the form of which is not materially affected, the con-
tained granules merely becoming more clearly defined. (See
Plate II. Jig. 5.)

The white globules in the blood of the frog are very
numerous ; they bear no similitude of form or size to the
elliptical red blood corpuscles, being usually perfectly sphe-

THE BLOOD. 69

rical, and scarcely more than a third of the dimensions of the
oval corpuscles. Thus, between the white globules in man
and the mammalia and those of reptiles, an opposite
relation of size in reference to the red blood discs exists ; for
while, in the former, the white corpuscles are larger than
the red globules, in the latter they are generally much smaller.
(See Plate 1. Jig. 1., Plate II. fig. 1.)

The plastic property possessed by the blood globules of all
animals belongs especially to that of the frog. The globules,
if trailed or drawn along the surface of a piece of glass, may
be elongated to thrice their original length, and made to
assume such forms as are altogether inconsistent with the
existence of a thin and distinct investing membrane.* (See
Plate II. ^.6.)

CAPILLARY CIRCULATION.

We have now considered the blood, both physiologically
and anatomically, out of the system, at rest and dead. We
have, in the next place, to treat of it within the body, living
and circulating.

The beautiful phenomenon of the capillary circulation
may be witnessed in the more transparent parts of several
animals ; as, for example, in the extremities of young spiders,
fins of fishes, in the gills of the tadpole and the newt, in the
tail of the water newt, in the web of the frog's foot, and in
the mesentery of the smaller mammalia. But it is seen to
the greatest possible advantage in the tongue of the frog ;
an organ peculiarly adapted for the representation of the

* The extraordinary elongation of which the blood globules of the frog
are susceptible, may be seen to very great advantage by adopting the
following little expedient : — A drop of blood being placed upon the object
glass previous to its coagulation, and allowed to remain there for a few
seconds, until symptoms of consolidation have manifested themselves, it is
then to be extended gently with two pins in opposite directions, if now
the microscope be brought to bear upon it, elongated corpuscles will be
seen in it in vast quantities. In the production of this change it is the
fibrin which is mainly concerned ; for it is through it that the extension
is communicated to the corpuscles.

70 ORGANISED FLUIDS.

circulation of the blood, from its extraordinary elasticity and
transparence. For a knowledge of this fact science is
indebted to a neighbour and friend of mine, l)r. A. Waller,
and by whom it was communicated some years ago to M.
Donne. For the exhibition of the circulation in the tongue
of the frog, in a satisfactory manner, it is necessary that the
animal should be secured in the following way : — A bandage
having been passed several times around the body of the
frog, so as to secure effectually the anterior extremities, it is
next to be fastened to a piece of cork by additional turns
of the bandage : this piece of cork should be very thin, six
or seven inches in length, by about ten in width, and per-
forated at one extremity by a square aperture, the diameter
of which should not be less than two thirds of an inch. To
the margin of this aperture, the mouth of the frog, in binding
it to the piece of cork, should be brought. The frog having
been thus effectually secured, the soft and pulp-like tongue
should be drawn out of the mouth by means of a pair of
forceps, and being spread over the surface of the aperture,
should be retained in position by from four to six pins, the
elasticity of the tissue of the tongue allowing of its extension
into a thin and transparent membrane with but little risk of
a rupture of the organ ; lastly, the piece of cork should be
fastened to the stage of the microscope, in such a position
that the tongue rests over the opening in the stage. These
preliminary arrangements being effected, and a low power
of the microscope being brought to bear upon it, a spec-
tacle of the highest interest and beauty is revealed to the
sight of the beholder. We have displayed before us, in
action, almost every tissue of the animal organisation, in its
simplest and clearest form and disposition — arteries, with
their accompanying veins and nerves ; muscular tissue ; the
blood, with its red and white globules ; epithelial cells ;
glands of the smallest possible complication of structure : and
these several parts are not merely visible, but their form,
disposition, construction, and normal mode of action, are all
distinctly apparent; the blood ever flowing, the muscles
contracting, and the glands secreting.

THE BLOOD. 71

The circulation in the tongue of the frog is best seen,
in the first instance, by means of low powers, a larger
surface of the organ being thus brought under view, and
a more exact idea obtained of the relative size and dispo-
sition of its numerous constituents. The arteries may be
distinguished from the veins by their fewer number, smaller
calibre, and by the fact that, while the veins increase in
diameter, in the direction of the course which the blood
contained in them pursues, the arteries decrease in the course
which the current follows in them. The arteries, from their
origin, diminish in size and multiply in number, by the con-
stant giving off of secondary branches ; the veins, on the
contrary, become enlarged during their progress, and lessen
in number, by the continual addition of subsidiary veins.
These differences, as well as the circumstance that the velocity
of the blood in the arteries is greater than in the veins, are
abundantly sufficient to distinguish the two orders of vessels
from each other. If, now, a somewhat higher power be
applied to the objects, we shall be able to dive still further
into the mysteries of organisation ; we shall not merely
perceive the general motion of the blood, but also that nearly
the entire mass of that fluid consists of red globules. We
shall be able to recognise clearly their form, and to see the
different modifications of shape which they undergo in passing
by each other, and in escaping any impediment which presents
itself to impede their progress. We shall perceive, likewise,
that, in the smaller capillaries, the globules circulate in single
series, and mingled with them will be noticed occasionally
a colourless globule, which, in the blood of the frog, is not
more than half the size of the elliptical corpuscle. (See PI.
V. Jig. 2.) Furthermore, it will be remarked that the
circulation does not flow on in an uninterrupted stream of
equal velocity, but that certain arrests of its motion occur.
These- are but momentary, and after each the current again
quickly flows on with the same speed as before : with each
action of the heart, also, a slight impulsion of the blood in
the capillaries may be clearly seen.

This instructive sight of the capillary circulation may be

G

72 OHGANISED FLUIDS.

viewed thus for hours, during the whole of which time the
blood will be seen flowing on with undiminished force. In
certain vessels, however, after a very long exposure of the
tongue to the action of the air, whereby its moisture is con-
tinually abstracted, and which acts, doubtless, as a source of
irritation, a number of the colourless globules will be seen to
have collected in the capillaries ; these adhere principally to
the sides of the vessels and to each other, thus leaving the
channel still free for the passage of the red globules, which
in their course sometimes rush against the white globules
with such violence as to detach one or more of them from
time to time from its adhesion to the walls of the vessel, and
which, rolling over once or twice, joins the general current of
the vessel, and is quickly carried out of view. It would
appear that any irritation affecting the capillary vessels,
even when applied to them outwardly, as, for example, weak
chemical solutions, gives rise to the phenomenon in question.
It is to be observed, however, that at all times considerable
numbers of white corpuscles circulate in the larger capil-
laries: these do not occur mixed up with the red blood
corpuscles ; but, as already remarked, are situated externally
between them and the inner wall of the capillaries. (See
Plate V.jg. 1.)

In the plastic power with which the red corpuscles are
endowed, we recognise a beautiful and important organic
adaptation of matter to the fulfilment of a special purpose.
Were it not for this plastic property, and were the red cor-
puscles of the blood, on the contrary, of a solid and unyield-
ing texture, it would follow, as an inevitable consequence of
the solidity of the globules, combined with their vast number,
that frequent interruption and stoppage of the circulation in
the capillaries would ensue, and which would, of course,
result in the complete derangement of the functions of the
entire economy.

I come now to record an observation which, so far as I am
informed, is without parallel. On one occasion, in examining
the tongue of a frog a portion of it broke away from the
remainder ; this I placed between two plates of glass, and

THE BLOOD. 73

submitted to examination, when, extraordinary to say, it
was perceived that the circulation was still vigorously main-
tained in the majority of the vessels. Anxious to know
how long this circulation would be continued, but fully ex-
pecting to see it cease every moment, myself and a friend,
John Coppin, Esq., of Lincoln's Inn, watched it for upwards
of an hour, at the end of which time the blood still flowed
onwards in many of the vessels, with scarcely abated vigour,
though in others, often the larger ones, the motion had alto-
gether ceased. The mutilated portion of the tongue was
then placed in water, in which it remained during the whole
of the night ; the next morning it was again examined, when
it was found that a tolerably active circulation still existed
in several of the smaller vessels. After this observation
the further examination of the fragment was abandoned.
The almost immediate cessation of the circulation, which
occurred in some of the larger vessels, admits of explanation
in the following way: — In some vessels the blood globules
were seen escaping from their open extremities ; this effusion
of the globules frequently continued for two or three mi-
nutes, until the entire contents of such vessels became poured
out, when of course the circulation within them ceased, the
circulating fluid being expended ; in other capillaries the
current was seen to stop long before their contents had been
exhausted, in which case it was usually to be remarked that
some of the blood corpuscles contained in the vessels had col-
lected around their orifices, thus producing an impediment
to the further maintenance of the current.

The foregoing observation is one of much interest and
importance ; for it seems to prove that the capillary circula-
tion is in a great measure independent of vital influences, and
that its persistence is mainly due to physical agencies.

With a few observations on the mucous follicles situated
on the, upper surface of the tongue of the frog we shall con-
clude our relation of the capillary circulation, as witnessed in
that organ. These follicles are glands reduced to the simplest
possible amount of organisation; they" are of a regularly
spherical form, and transparent texture ; they are situated in

a 2

74 ORGANISED FLUIDS.

the mucous membrane of the tongue, to the thickness of
which they are entirely confined, as proved by the fact that,
when that membrane is dissected off, by means of a needle the
glands are raised along with it. Into each of these glands
may be seen entering it on one side, and quitting it usually
on the opposite, one of the smallest of the capillary vessels,
in which the blood corpuscles pass usually in single series,
this vessel in its passage through the gland describes usually
a tortuous course ; and within it the blood corpuscles are seen
to be in a state of increased and incessant activity, appearing
to move, as it were, in a vortex, this appearance resulting
from the curvatures described by the vessel. (See Plate VII.
figs. 1, 2.)

It might be expected that, in a gland of such simple con-
stitution, the exact process of secretion would be rendered
apparent; in this expectation, however, we are doomed to
disappointment, no action beyond that which we have already
related being visible within it. An endosmotic action does
doubtless take place between the contents of the gland and
those of the vessel which permeates it, whereby a peculiar
product is obtained from the blood, to be fashioned and
assimilated by certain powers inherent in the gland itself,
and the precise nature of which powers is unknown to us, and
it is probable that it never will be revealed. Pass we now
to the description of the circulation in the embryo of the
chick, which possesses points of interest distinct from those
observed in the tongue of the frog.

CIRCULATION IN THE EMBRYO OF THE CHICK.

The process by which the circulation in the embryo of the
chick is displayed is one which requires considerable delicacy
of manipulation ; the care, however, which it is necessary to
bestow upon it, for its successful exhibition, is amply repaid
by the surpassing beauty of the spectacle which presents
itself to the beholder. It is best seen in the third, fourth,
and fifth days of the incubation of the egg.

THE BLOOD. 75

For the purpose of showing it satisfactorily the egg should
be broken at the side, and a portion of the shell cautiously
removed, without at the same time raising with it the subjacent
membrane (membrana testae) ; this should next be peeled off
with the same degree of caution as that with which the shell
itself was previously raised.

Immediately beneath this membrane the yolk itself will be
seen floating ^in the midst of the colourless albumen, and
sustained in position by the beautifully spiral chalazce, which
proceeding from the yolk are fastened into that portion of
the membrana testce which corresponds with the poles of the
egg-shell.

Imbedded in the surface of the yolk of an egg on the
third, fourth, and fifth days of its incubation, the embryo
will be visible, and issuing from its umbilicus will be seen the
vessels which ramify in such graceful order through the
membrane of the allantois.

The embryo is almost invariably placed uppermost in the
yolk, so that it most generally presents itself beneath, what-
ever part of the shell has been broken. This position results
from the lighter specific gravity, and is, moreover, facilitated
by the spiral formation of the chalazge.

The purposes fulfilled by this position of the embryo are
obvious and- striking, it being thus so placed as to receive
directly the caloric which is continually emanating from the
parent hen, and being also more immediately submitted to
the influence of the oxygen of the air.

In an embryo then thus placed in situ, in the third, fourth,
and fifth days of its development, and with the unaided sight,
the rudiments of almost all the organs and members may be
clearly recognised, the eye and the regular contractions of the
heart, together with the vessels departing from it to ramify
through the allantois, being particularly conspicuous. With
a low/ power of the microscope the course of the blood in
the vessels, together with the form and size of the white
and red corpuscles, may be clearly distinguished.

The ramifications of the vessels in the "allantois presents an
arborescent distribution ; their entire course may be traced

76 ORGANISED FLUIDS.

from their commencement in the aorta to their termination
on the border of the membrane of the allantois.

Now the great point of interest in the circulation of the
chick is that the passage of the blood may be witnessed
throughout ; thus the blood expelled from the heart by the
contraction of the ventricle into the aorta may be traced
through this vessel, and all its subsequent divisions and sub-
divisions, until it reaches the ultimate arterial radicles, passes
from these into the corresponding radicles of the veins, and
from these again into the larger venous trunks, by which it
is reconveyed to the heart, the circle of the circulation being
thereby completed.

There are two ways in which the circulation in the em-
bryo of the fowl may be viewed, either while it is still
occupying its natural position on the surface of the yolk,
and this I think is by far the most preferable method ; or the
embryo may be altogether detached from the yolk by means
of an armed needle, and subsequently placed on a watch-glass
filled with warm water at a temperature of 96°. During the
operation of detaching the embryo, the egg itself should also
be immersed in water at the temperature just mentioned.
This latter process is one, however, of much nicety, and
frequently fails in consequence of the rupture of some of the
finer vessels, the blood becoming effused, the different parts
of the embryo obscured, and a stoppage put to the cir-
culation.

But it is not alone the contemplation of the circulation in
the embryo of the chick which is so interesting and in-
structive ; the study of the entire development of the ovum
from its commencement to its termination reveals facts of
the highest importance and full of wonder.

The examination of the blood of the embryo fowl is
especially instructive, the mode of formation of the red cor-
puscles admitting of determination in a manner the most
satisfactory.

In the red corpuscles contained in the blood of the embryo
in the first days of its development, a remarkable variation of
size will be detected, some of them being three or four times

THE BLOOD. 77

larger than others, and the smallest consisting almost entirely
of a nucleus surrounded by a faint and delicate envelope.
Between the two extremes of size every possible gradation is
presented. (See Plate IX. fiy. 1.)

This variation in the dimensions of the corpuscles becomes
scarcely less apparent if they be immersed in water, in which
they become perfectly spherical. (See Plate IX. fig. 2.)

A diversity of size almost as remarkable as that which
exists between the red blood corpuscles of the embryo fowl
will be observed also in those of the young frog which has
but just emerged from its tadpole state. If a drop of the
blood of this young frog be compared with that of a full-
grown frog, the corpuscles in the former will be remarked to
vary greatly in dimensions, while in the latter they will be
seen to present a much greater uniformity of size. (See
Plate IX. figs. 4, 5.)

Now, the inferences to be deduced from this great diversity
of size are palpable, and are, first, that the red blood corpuscle
is at its origin small, and only attains its full dimensions after
a given period ; and, second, that the nucleus is the part of
the corpuscle which is first formed, the coloured investing
and perfectly smooth portion of it being gradually developed
around this subsequently. This view is inconsistent with the
notion entertained by many that the red blood corpuscles
result from the gradual assumption by the white globules of
the characteristic distinctions of the red blood discs, for were
this really the case we should be at a complete loss to account
for the remarkable differences of size to which we have
adverted.

A similar mode of development to that which has been
described as belonging to the red blood corpuscles of the
embryo fowl appertains also, I believe, to that of all the
Oviparous Vertebrata.

The development of the coloured blood corpuscle of the
Mammalia, I conceive to agree also with that of the other
Vertebrata in the fact of their being small at first, and sub-
sequently and gradually attaining their normal proportions,

II

78 ORGANISED FLUIDS.

but to differ from that of the Oviparous Vertebrata in not
being developed around a central nucleus.

DISSOLUTION OF BLOOD CORPUSCLES.

But if the blood of the embryo fowl is well adapted for the
study of the origin and development of red blood corpuscles,
that of the adult fowl is no less fitted for ascertaining their
end and final destination.

Some observers have entertained the idea, already ex-
pressed in this work, that the older blood discs become melted
down in the liquor sanguinis, and thus, by their dissolution,
increasing the amount of fibrin held dissolved in that liquid.
To the adoption of this notion they were driven because
they were unable to dispose of the red blood disc in any
other way, and which other facts had made apparent to them
could not be regarded as persistent structures.

In proof of the accuracy of this statement respecting the
melting down of the corpuscles, they had not, however, a
particle of direct evidence to adduce. I will now proceed
to show that the view referred to may be substantiated by
positive observation.

In almost every drop of the blood of an adult fowl a
number of certain pale and usually colourless corpuscles will
be seen, having a nucleus of the same size and structure as
that of the ordinary red blood disc distinctly visible in the
midst, the investing portion of each corpuscle at the same
time being invariably smooth and destitute of granules.

These corpuscles vary in size, in form, and in colour ; the
larger ones, which are equal in dimensions to the fully deve-
loped blood discs, usually retain a faint coloration, and are
invariably of an oval form, while the smaller ones, many of
which consist of merely a nucleus and a closely fitting-
envelope, are perfectly colourless, and for the most part,
although not always, spherical. (See Plate IX. Jig. 3.)

Now there is no difficulty whatever in detecting these pale
and mostly spherical corpuscles with a good instrument, nor

THE BLOOD. 79

is there the slightest danger of confounding them with the
white corpuscles, which are also to be seen retaining their
uniformly molecular aspect.

The corpuscles just described exist not merely in the blood
of the adult fowl, but they may be detected, with similar
facility, in every Oviparous Vertebrate animal the blood of
which I have examined ; and they abound in the blood of
tritons and frogs. (Plate IX. fig. 5.)

But further there may be detected in the blood of adult
Oviparous Vertebrata, not merely the delicate and pale cor-
puscles referred to, but also numbers of naked nuclei, that
is, of nuclei deprived of all trace of investing membrane.
(See Plate IX. figs. 3 and 5.)

These nuclei should, however, be examined with care, and
a nice adjustment of the object-glass ; for it will be found, on
close examination, that many of them, though appearing at
first sight to be naked, are not really so, but are invested by
a scarcely perceptible envelope.

Now these large and slightly coloured oval corpuscles, the
smaller perfectly colourless and mostly spherical ones, and
the naked nuclei, represent progressive states of the dissolu-
tion of the red blood disc.

When first I noticed these pale corpuscles and nuclei, I
was disposed to think that they represented stages in the
upward development of the red blood disc : this opinion was,
however, dispelled, by observing that the pale and colourless
corpuscles often exceeded greatly in size the smaller true and
coloured blood corpuscles.

There is one circumstance connected with these pale cor-
puscles which does not appear to admit of any very satisfac-
tory explanation, viz. their occurrence on the field of the
microscope in groups.

A word or two as to the seat or locality in which the work
of development of blood corpuscles, and subsequent dissolu-
tion of them, is conducted. Physiologists appear always to
have been on the look-out for some organ of the body, the
especial purpose of which in the animal economy they con-

H 2

80 ORGANISED FLUIDS.

ceived should be the elaboration of the blood corpuscles ; and
some of them, as Hewson and Donne, not knowing well
what office ought to be assigned to that much discussed
organ, the spleen, have on various grounds considered it to
be the laboratory in which the work of development is carried
on. Of the dissolution of the red blood discs no definite or
decided observations hitherto appear to have been made by
any observer.

Observation has convinced me that the development of
blood corpuscles is not assigned to any particular organ of
the body, but that it occurs within the blood-vessels during
the whole course of the circulation and of life. During the
first formation of the blood in early embryonic life, the
corpuscles are said to be formed in the cells, which by their
union with each other give origin to the capillary vessels.

Further, it is probable, that, while it is in arterial blood
that the work of development of blood corpuscles is most
active, it is in the venous fluid that the converse work of
dissolution is mainly effected.

The development of blood corpuscles is also most active in
very early life, when growth is rapid, and it is likewise
more active than ordinary in adult existence, after haemor-
rhages, and in persons of the plethoric diathesis. In like
manner it may be presumed that the dissolution of red blood
corpuscles proceeds more quickly in anemic conditions of the
system, and in old age, while at the same time, at the latter
period, development of new corpuscles is more tardy.

It is now hoped that a more satisfactory explanation of
the origin and end of the red blood disc has been given than
it was feared, when the writer first approached the considera-
tion of these difficult, though most important, questions, it
would have been in his power to have afforded.

VENOUS AND ARTERIAL BLOOD.

Venous and arterial blood differ in certain important re-
spects from each other ; arterial blood is of a brighter colour,

THE BLOOD. 81

and coagulates more firmly than that which is venous. The
difference in colour is due to the presence in the former of
oxygen, and in the latter of carbon in a state of combination
not yet well determined. Venous blood, when exposed to
the action of oxygen, soon acquires the vivid red colour of
arterial blood, and this, when submitted to the influence of
carbonic acid, as speedily assumes the dark hue of venous
blood.

The greater or less firmness in the clot formed is owing to
the different amount of fibrin contained in the two fluids, and
which is greatest in that which is arterial, the coagulum
of which, therefore, possesses the greatest density. The dif-
ferences detected by the microscope in the blood corpuscles
of arterial and venous blood are scarcely appreciable. Gerber
states that the " tint of colour exhibited is various ; bright in
the globule of arterial blood, dark red and somewhat streaky
in that of venous blood :" this difference of colour, which doubt-
less exists, it is easier to infer than positively to demonstrate
by means of the microscope. While arterial blood is richer
in salts, venous blood contains a greater proportion of fatty
matter.

There are several substances which effect a change in the
colour of the blood : thus oxygen, the concentrated solutions
of salts with an alkaline base, and sugar turn dark venous
of a bright florid or arterial red, this reddening being ac-
complished by the salts and sugar, even when the blood is
placed in a vacuum, or an atmosphere of hydrogen, nitrogen,
or carbonic acid gases.

Newbigging* hath also remarked that venous blood takes
the tint of vermilion in a cup, at those situations at which it
is painted with the green oxide of chrome, and Taylor f has
confirmed the observation that the colours which contain the
oxide of chrome brighten the tint of blood.

On 'the other hand, bright or arterial blood is darkened,
or even blackened, by contact with carbonic and oxalic acids,

* Edinburgh New Philosophical Journal, October, 1839.
f Lancet, February, 1840.

u 3

82 ORGANISED FLUIDS.

and by its admixture, according to Henle, with distilled
water.

Sulphuric acid, and other acids which are agitated with
the blood, change its colour from red to blackish brown.

The nitrous and nitric oxides cause vermilion blood to take
a deep purple tint.*

The power possessed by those substances which brighten
the colour of dark venous blood is supposed to be derived
from the oxygen which they contain, and by means of which
a chemical transformation in the condition of the red element
of the blood, the hematine, is effected, a portion of oxygen
being absorbed during the change of colour. Those sub-
stances, however, which cause arterial blood to assume the
tint of venous blood are presumed to exert their influence
by means of the carbon of which they are compounded, and
a portion of which becomes imbibed during the work of
transmutation.

Henle, nevertheless, considers that these several alterations
of colour arise rather from mechanical than chemical causes,
and that they depend upon the state of aggregation of the
particles of the colouring matter, these being differently dis-
posed according to the nature of the reagent employed.

Thus Henle remarks f, "It is evident that the colour of
the blood is brightened under the influence of substances
which oppose the dissolution of the hematine in the serum
and maintain or re-establish the flat form of the corpuscles,
as the concentrated solutions of salts and of sugar, while pure
water, which dissolves the colouring matter and causes the
corpuscles to swell, deepens the colour of the blood."

Hamburger J, according to Henle, has even observed that
weak solutions of the chlorides render the colour of the blood
deeper, while their concentrated solutions make it pass to
vermilion.

Again, according to the observations of Schultz, it would
appear that the red blood corpuscles are flattened by the

* Henle, Anatomic Generate, tome premier, page 471.

f Loc. cit. page 471.

| Hamburger, Exp. circa Sanguinis Coagulationem, pp. 32. 42,

THE BLOOD. 83

action of oxygen, while the effect of the application of car-
bonic acid is to cause them to swell up, and assume a more
or less globular figure.

On this fact Henle reasons thus : accompanying these
changes of form there are alterations in the state of aggrega-
tion of the colouring matter of the corpuscles; thus, in
oxygen, or in any saline solutions, the plasma remains clear
and colourless, the blood discs being flattened, and the colour-
ing matter contained within them condensed, while in carbonic
acid or water the plasma becomes coloured by the escape of
a portion of the hematine from the corpuscles, which swell
up, and assume a form approaching more or less the globular.
Now the difference in colour between venous and arterial
blood Henle maintains may be accounted for by reference
to the form of the corpuscles, and the consequent condition
of the particles of the colouring matter.

And it is also by reference to the state of the colouring
matter that Henle accounts for the fact that blood which
has once acquired a very dark colour is thereby rendered
incapable of re-assuming the bright hue of arterial blood
on the application of oxygen or saline solutions, because, he
says, that the pigment which had escaped into the plasma,
under the influence of the carbonic acid, cannot be made to
enter into the corpuscles again, when by means of oxygen
they are again flattened.

The colour of the blood, then, according to Henle, depends
upon the single fact of the form of the corpuscle, and that
this colour is so much the more bright as these are flat.

Finally, in support of his theory, Henle refers to changes
of colour presented by certain inorganic substances from an
alteration in the state of aggregation of its constituent par-
ticles : thus it is well known that the ioduret of mercury
recently sublimed is yellow ; in cooling its colour passes to
scarlet, and pressure determines this change in an instanta-
neous manner.

Such is Henle's mechanical theory of tjie changes of colour
experienced by the blood on the addition of reagents, a theory
which, however ingenious it may be, I deem to be insufficient

ii 4

84 ORGANISED FLUIDS.

to account for the very remarkable alterations of colour to
which the vital fluid is subject.

The changes of colour of dark blood to a vermilion
hue, and of this again to the deep tint of venous blood,
admit of a chemical explanation being given, the essential
element of the former change being oxygen gas, and of the
latter carbonic acid gas. Thus, even the remarkable effect
of the application of the chlorides may be accounted for by
reference to the well-known operation of chlorine as a bleach-
ing agent, viz. through the power which it possesses of
depriving water of its hydrogen, and altering the state of
combination of the oxygen.

With respect to the observations of Schultz on the effect
of carbonic acid and of oxygen in altering the form of the
red blood corpuscles, and on which fact the entire of Henle's
theory rests, I would observe that, in conjunction with Mr.
Miller, the gentleman who manifests so much of patience,
skill, and intelligence in the execution of the drawings of
this work, and who is moreover an excellent chemist, I have
made many experiments with the view of ascertaining the
power possessed by the former reagent in modifying the
form of the elliptical corpuscles of the blood of the frog, the
blood being in some cases submitted to the direct action of
the gas, and in others the animal itself being subjected to
its influence.

The result of these experiments, on my mind, is the con-
viction that the effect of this gas on the figure of the
corpuscle is not appreciable. I am therefore disposed to
allow but little weight to the mechanical theory of the changes
of colour experienced by the blood.

Venous blood does not present precisely the same tint of
colour or the same characters in all parts' of the system : thus
the blood found in the vena porta is deeper in colour than
any other venous blood, and, according to Schultz, it does not
redden either on the application of oxygen gas or of salts,
and does not coagulate, or gives but a divided clot ; it is
richer in water, in cruor, and in fat, and poorer in albumen,
than ordinary venous blood.

THE BLOOD. 85

It would be a point of much interest to determine whether
arterial or venous blood contains the greatest number of
blood corpuscles. The experiments which have hitherto
been made with the view of determining this question are
most unsatisfactory, and contradict each other.

MODIFICATIONS OF THE BLOOD CORPUSCLES THE RESULTS
OF DIFFERENT EXTERNAL AGENCIES.

Peculiar Modification the Effect of commencing Desiccation.

If the red corpuscles be examined a few minutes after their
abstraction from the system, in a drop of blood which has
been spread out between two plates of thin glass, it will be
seen that many of them, and especially those which are situ-
ated near the margin of the drop, present an appearance very
different from that which belongs to them in their ordinary
and natural condition. They now no longer exhibit the
flattened form with the central depression, but have become
converted into little spheres, the surface of which, instead of
being smooth, is now rough and tuberculated. (See Plate I.
Jig. 5.) Blood corpuscles thus changed have been compared
to mulberries in appearance. This alteration is supposed by
Donne to depend upon commencing desiccation, and to arise
from deficiency of serum, the mulberry-like globules being
but imperfectly bathed in that liquid. No very satisfactory
explanation of the exact nature of the change has as yet
been given. MM. Andral and Gaverret * suppose that the
mammillated appearance of the corpuscles arises from the
adherence to the surface of the globules, of a number of the
exceedingly minute molecules of the fibrin ; this explanation
is probably more ingenious than correct. If a number of the
altered globules be carefully and closely examined, it will be
remarked that they do not all exhibit precisely similar ap-
pearances; that in some globules, for instance, it will be
observed that the contour is but slightly broken or indented,
that in others the indentations of the surface are more con-

* Essai d'Hemalogie Pathologique, par G. Andral, page 23.

86 ORGANISED FLUIDS.

siderable, and the small spaces between them consequently
more prominent ; and again in other globules, and which
are indeed by far the most numerous, it will be obvious
that the whole surface has become distinctly tuberculated,
each tubercle, of which there are several to each globule,
appearing to be of a spherical form, and resembling a
minute bubble of some gas, probably of oxygen, or carbon,
according as the blood is arterial or venous. That they are
really of a gaseous nature is proved, I think, by the fact of
their gradual formation as well as dissipation. M. Andral
states, that in blood which has been deprived of its fibrin, the
corpuscles never exhibit the peculiar granulated or tuber-
culated aspect which we have described, and this fact he
adduces in support of the opinion entertained by him, that
this peculiar condition of the globules is due to the accumu-
lation on their surface of the molecules derived from the
fibrin.

Mr. John Quekett is also of the opinion that this peculiar
condition of the blood globules of which we have been speak-
ing, is occasioned by the adherence to their edges of granules
which he considers to be derived from the interior of the
corpuscles themselves. See " Observations on the Blood
Discs and their Contents," Microscopic Journal, vol. i. p. 65.
For further observations on this granulated appearance of
the corpuscles, see Part I. p. 31.

MODIFICATIONS THE RESULTS OF DECOMPOSITION OCCUR-
RING IN BLOOD ABANDONED TO ITSELF WITHOUT THE
BODY.

In blood abandoned to itself and exposed to atmospheric
influences, changes of form and appearance speedily begin to
manifest themselves in the red corpuscles. These changes
occur in regular order ; they first become wrinkled, deformed,
and tuberculated ; they next lose their flattened and disc-like
shape, becoming globular and smooth ; their colouring matter
escapes from them, and they present a livid hue. In this
condition they are with difficulty discoverable in the blood ;

THE BLOOD. 87

finally, they dissolve, and all traces of them disappear. These
successive changes are all produced in the course of a very
few hours : the exact period, however, varies with the tem-
perature of the atmosphere and actual condition of the blood
when extracted from the system.

MODIFICATIONS THE RESULTS OF DECOMPOSITION OCCUR-
RING IN BLOOD WITHIN THE BODY AFTER DEATH.

The changes which we have described as occurring in blood
abandoned to itself without the system, take place likewise
in the red corpuscle of that which is contained within the
body after death, and this even with a greater degree of
quickness than in the former case ; the time, however,
bears a relation to atmospheric conditions, to temperature,
as well as, especially, to the nature of the malady to which
the patient has succumbed. If the affection which has oc-
casioned death be of a nature to exhaust profoundly the vital
powers, if it be a chronic disease of long duration, as a typhoid
fever, the period requisite for the production of these changes
will be very short ; so brief, indeed, that the alterations may
be detected in the corpuscles almost immediately after the
extinction of life. It is of much importance that the changes
resulting from decomposition, and which occur in the dead
body, should not be confounded with real and pathological
alterations of the red corpuscles.

CAUSES OF INFLAMMATION.
Exciting Cause.

The fact which has been alluded to in the preceding
pages, of the accumulation of the white and red corpuscles
in the tongue and web of the frog as a consequence of the
application of irritation, bears a close relation to the phe-
nomena of inflammation, and shows that the exciting cause
of inflammation, whatever it may be, such as a blow, expo-
sure to cold, burns, scalds, or the application of irritating sub-
stances, acts usually through the medium of the nervous

88 OKGANISED FLUIDS,

system, the impression produced on it impinging upon the
structures to which the ultimate nervous fibrillse are distri-
buted, viz. the vessels in the which a series of results ensue
which together constitute the condition of inflammation.

Proximate Cause.

When the white and the red corpuscles of the blood accu-
mulate in the capillaries of a part in normal quantity, those
vessels may be considered to be in a state of " vital tur-
gescence;" when, however, they are present in those vessels
in abnormal proportion, then the capillaries may be said to
be in a state of " inflammatory turgescence."

Now the term " congestion" indicates a condition of the
vessels intermediate between vital and inflammatory turges-
cence, and which may be denominated " congestive turges-
cence."

In vital turgescence, a phrase which indicates the condition
of the vessels in a state of normal nutrition, the capillaries
are slightly increased in calibre, and are pervaded by an
unusual, though perfectly normal number of corpuscles, both
red and white, but especially of the latter, some of which
adhere to the walls of the vessels.

In congestive turgescence, or in congestion, the calibre of
the capillaries is more considerably increased in size, and a
greater and abnormal number of white and red corpuscles,
especially the former, are collected in the vessels. These cor-
puscles, if the turgescence terminates in resolution without
advancing to the condition of inflammation, do not undergo
any structural changes, but enter again into the circulation,
their removal being determined by the discontinuance of the
exciting cause, and by the vis a tergo of the circulation, which
drives the corpuscles onwards.

Lastly, in inflammatory turgescence the diameter is very
considerably enlarged, and their interior is filled with a very
greatly increased and abnormal quantity of white and red
corpuscles, these accumulating to such an extent as either
to seriously obstruct, or altogether destroy, the circulation in

THE BLOOD. 89

those vessels This condition of the vessels is always ac-
companied by certain structural alterations, which affect not
merely the corpuscles themselves, but also the vessels and
parts adjacent to them ; these alterations being merely at-
tributable to the impediment presented to the onward pro-
gress of the blood in the capillaries by the accumulation in
them of the blood corpuscles.

We now know that the proximate cause of inflammation
consists in an abnormal accumulation of the corpuscles of the
blood in the minute capillary vessels, and which accumulation
we perceive must inevitably impede the function of the part
in which the vessels are thus surcharged, alter its structure,
and finally tend to a sympathetic disturbance of the entire
economy. For this discovery we are indebted to the mi-
croscope. It will thus be seen that some of the ancient
hypotheses in reference to the proximate cause of inflamma-
tion were not so very far wrong, and that most of them
recognise the fact that it is the capillary vessels and blood
corpuscles which are mainly concerned in the production of
the phenomena of inflammation.

Finally, inflammation may, like congestion, terminate in
resolution ; but, unlike congestion, it always leaves per-
manent traces of its visitation, the resolution being but in-
complete. It may terminate, also, in " hepatization," or in
" purulent infiltration." The fibrin of the blood is the chief
agent in producing the consolidation of the structure known
by the term hepatization, while it is the white corpuscles
analogous to those of the blood, as will be seen hereafter,
that give rise to the purulent formation.

PATHOLOGY OF THE BLOOD.

We come now to the consideration of the most important
division of our Chapter upon the blood, viz. that which treats
of the pathological changes which that fluid undergoes, and
a full and clear understanding of which is so necessary to the
safe and successful treatment of disease.

These pathological alterations are numerous, and engage

90 ORGANISED FLUIDS.

not merely the solid constituents of the blood, the white and
red corpuscles, but also its fluid elements, the fibrin and the
albumen ; the abnormal conditions of each of which principles
of the blood we shall find to be accompanied by a distinct
train of morbid phenomena. It may be said that the fibrin
and the albumen being entirely of a fluid nature, and not
holding solid particles of any magnitude in suspension, they
ought not to be considered in a work devoted to micro-
scopic anatomy. We shall find, however, that these several
constituents of the blood are so intimately associated that, in
order to understand any one of them fully, it is necessary
that we should possess a knowledge of the others also, and
therefore I consider that their discussion conies within the
legitimate scope of this work.

For much of our knowledge of the pathology of the blood
we are indebted to the united researches of MM. Andral and
Gavarret, to whose valuable essay we shall have occasion
hereinafter to make frequent reference.

Pathology of the Red Corpuscles of the Blood.

The scale of the red corpuscles of the blood, relative to that
of the other elements, varies considerably, even in states of
health. The mean proportion of red corpuscles is estimated
by MM. Andral and Gavarret at 127 in every thousand parts
of the vital fluid. This scale may, however, be elevated to
140, or depressed to 110 ; the variations in the quantity of
the red globules writhin these limits being compatible, how-
ever, with a physiological or healthy condition of the blood,
although the higher scale, 140, is allied to a state of plethora,
while the lower, 110, borders upon the opposite state, of
anaemia, and both of which may be regarded, if not as dis-
eases in themselves, at least as powerful, auxiliary, and pre-
disposing causes of many morbid conditions of the system.

THE BLOOD. 91

Increase in the Number of the Red Corpuscles. — Plethora.

An increase in the number of the red corpuscles of the
blood exists in that condition of the system which has been
denominated the plethoric, and which increase constitutes its
chief element. The authors already cited found the mean
proportion of the red globules in the thirty-one cases in
which the blood was submitted to examination, to be in
every thousand parts 141 ; the minimum 131, and the
maximum 154. With this increase in the number of the
red corpuscles, it was not found that any other element of
the blood had become either augmented or diminished.

The symptoms which indicate the existence of plethora,
whether they be organic, or functional and mental, all admit
of a ready and satisfactory explanation by a reference to the
increased quantity of the red corpuscles.

The existence of a state of plethora implies high vital
powers ; there seems to be in the plethoric, as it were a super-
abundance of life, and which is imparted to all the parts and
organs of the system alike. The plethoric diathesis would
appear to be more frequently hereditary than acquired, and
no degree of high and nutritious feeding will induce it in
the system of some persons, although an opposite or anemic
state may be produced in all by the abstraction of a proper
quantity of suitable nourishment.

The general symptoms which characterise the plethoric
diathesis, are a well-developed muscular system, voluminous
thorax, a deep-coloured skin, and a ruddy complexion ; coin-
ciding with these physical and outward appearances, we find
much functional activity to exist, the respiration is free and
unembarrassed, the digestion quick and active, the pulse is
full and strong, and the motions of the body are performed
with celerity and power. This functional activity appertains
also to the operations and emotions of the mind ; the plethoric
is quick in thought, hasty and violent in temper.

The injected skin, and the brilliant complexion, are to be
explained by reference to the increased quantity of the red
corpuscles which circulate in the blood, and which alone arc

92 ORGANISED FLUIDS.

the seat of colour, while the great organic development and
the functional and mental activity depend par.tially upon the
greater amount of oxygen of which the blood corpuscles are
the carriers to all parts of the system, and which is so essen-
tial to the vigorous performance of the vital processes and
manifestations.

The characters exhibited by blood which has been with-
drawn from the system are likewise consistently explained
by reference to the augmented quantity of the red blood
corpuscles ; thus the blood in plethora, immediately on its
abstraction, is observed to be of a deeper colour, and the clot
formed subsequently by its coagulation of a larger size ; this,
although voluminous, is of mean density, and never exhibits
the buffy coat, which circumstances are accounted for by the
fact that, as already remarked, in the blood of plethoric per-
sons there exists necessarily no excess of fibrin.

Accompanying the plethoric condition, and dependent
upon it, we have frequently a number of grave pathological
manifestations, apoplexies, haemorrhages, congestions, vertigos,
noises in the ears, and flashes of light before the eyes ; all of
which are most generally greatly relieved by venesection,
which withdraws from the system a portion of the super-
abundant red blood corpuscles.

Decrease in the Number of the Red Corpuscles. — Ancemia.

The term anaemia indicates a state of the system the
very reverse of that which obtains in plethora : in it the
red blood corpuscles, instead of being in excess, are greatly
below the physiological standard. The authors quoted found,
in sixteen cases of commencing anaemia, the mean of the red
globular element of the blood to be 109; and in twenty-four
examples of confirmed anaemia, 65; that is, almost one-half less
than the standard which belongs to health. In one case of
anaemia in the human subject, M. Anclral found the scale to
descend so low as 28 ; a depression which one would scarcely
suppose to be compatible with life.

In spontaneous anaemia it is stated, that it is the globules

THE BLOOD. 93

alone which are affected, and that in it, as in plethora, the
other elements ' of the blood undergo neither augmentation
nor diminution : in accidental anaemia, however, resulting from
direct losses of the vital fluid, the normal standard is of
course disturbed : for in hemorrhages, and especially in first
bleedings, it is chiefly the globules which escape, and this
would lead to the relatively higher scale for the fibrin.

As ana3mia depends upon a condition of the blood the very
opposite of that which exists in plethora, the symptoms also
in these two constitutional conditions are the reverse of
each other ; instead of the vascular and injected skin, we find
it to be livid and exsanguine, these appearances extending also
to the mucous membranes ; in place of the accelerated func-
tions, we notice that the vital actions are sluggishly per-
formed, and that the mental powers are feeble.

The blood abstracted from the system exhibits a paler
tint than is usual, and the clot is small and floats in the
midst of the serum, which is very abundant ; small, however,
as the crassamentum is, it is yet of considerable density, as
might be expected from the remark which has already been
made, viz. that the fibrin exists in its normal proportion, and
therefore is in excess over the globular element of the blood
which is deficient ; it is for the same reason also that we fre-
quently notice upon the surface of the clot the buffy coat :
the density of the clot, and of the crust which covers it, are so
much the more marked as the anemia is considerable.

The existence of the miscalled inflammatory crust in
anaemic states has long been known, although not satisfac-
torily accounted for.

The pathological disorders to which anrcmia gives origin
are numerous : the general debility, the disordered digestion,
the difficult respiration, the palpitations of the heart, the
faint ings, are well remembered.

Tliepe is a state of the system, well described by Andral,
which simulates plethora, but which is really allied to
nniumia, and to which the term false plethora might be given ;
in this we have the injected skin and many other indications
of plethora; it is to be diagnosed, however, by means of the

I

94 ORGANISED FLUIDS.

constitutional disturbances which coincide with those of
ordinary anaemia.

It is in anaemic conditions of the system that we detect the
remarkable bruit de soufflet, in reference to which Andral
in his essay on the blood has instituted some useful re-
searches, the chief result of which is the establishment of
the fact, that the intensity and persistence of the bruit is in
exact proportion to the severity of the anemia.

In pregnancy we have a slight example of an anaemic con-
dition of the blood, and in chlorosis we see anaemia to prevail
with various degrees of severity. In phthisis the scale of
the red corpuscles is likewise much reduced, but not to the
extent to which its reduction is witnessed in chlorosis ; and
this is the more remarkable from the circumstance that in the
former disease it is those organs which are affected, between
which and the red corpuscles a close connection exists. In
cancer also the number of the blood corpuscles is reduced : in
phthisis the diminution precedes and accompanies the whole
course of the affection, while in cancer it occurs only at an
advanced period of the disease, and arises principally from
the continual losses of blood to which cancerous patients are
so subject. In disordered states of the system purely nervous
we find also the red element of the blood to be deficient.
The scale of the red globules in a number of cases in which
the blood of phthisical patients was submitted to examination
oscillated between 80 and 100.

Increase in the Number of the Red Corpuscles under the
Influence of Recovery and of certain Medicinal Agents.

Under the influence of recovery the red blood corpuscles
increase in number, and have a tendency to attain to their
physiological standard, which, when reached, they may even
exceed, until at length they mount up to the scale which
denotes the existence of the plethoric condition.

Certain medicinal substances exhibit likewise much influence
in increasing the number of the red corpuscles ; of these the
most remarkable is iron, under the effect of which remedy

THE BLOOD. 95

the pale complexion of the chlorotic will be seen gradually to
acquire the tone and colour indicative of health and strength.

Effect of Disease upon the White Corpuscles.

The white corpuscles of the blood have not hitherto
received that amount of attention which has been bestowed
by so many observers upon their associates the red corpuscles ;
indeed, it is only in these later times that their investigation
has been pursued with that degree of care, which, from their
importance, they so well merit, and observations are still
wanting upon their condition in states of disease. It has
already been remarked that an increase in their number has
been frequently observed to occur in various diseases, and
especially in such as are accompanied^by suppuration and great
exhaustion of the vital powers. Of the precise cause of this
increase no very satisfactory explanation has been offered,
and the following attempt at an explanation is presented to
the consideration of the reader with much hesitation. In most
serious disorders the function of nutrition and assimilation
is more or less impeded. Now, supposing that these white
corpuscles are essentially connected with nutrition, and that
while the cause which determines their formation still con-
tinues in operation, that which regulates their assimilation
is suspended, there would result, as an inevitable conse-
quence, an accumulation of the white corpuscles in the blood.

Deficiency of Fibrin in Fevers, as in Typhus, Small-pox,
Scarlatina, Measles.

The important researches of MM. Andral and Gavarret
establish the fact, that, in that much debated class of maladies,
fevers, there is a deficiency in the blood of its spontaneously
coagulable element, the fibrin. In the Essai d'Hematologie
no scale of the diminution in the amount of fibrin is given ; it is
shown, however, that in some fevers, and especially in the com-
mencement, the deficiency of fibrin may be but small ; and
that in others, particularly when symptoms of putridity have

i 2

96 ORGANISED FLUIDS.

manifested themselves, and which may ultimately complicate
all fevers, the loss of fibrin is considerable, and further that the
intensity of the symptoms is in direct relation to this loss,
being great when the diminution of fibrin is also great.

It is not to be understood, however, that the deficiency of
fibrin constitutes the essence or real and specific cause of fever ;
for this we must look to some other agent or fact, probably
to the contamination of the general mass of the blood by the
imbibition of some deleterious and subtle miasma. That the
deficiency in the amount of fibrin is not the cause of fevers
we find to be proved by the facts that this class of maladies
attacks persons of every possible variety of habit and con-
stitution, and in many of whom, at the onset of the disorder,
no deficiency of fibrin can be detected ; and the same view
is likewise confirmed by the circumstance which must have
attracted the attention of every physician, viz. that the
primary condition and inherent powers of the system deter-
mine and control but to a comparatively slight extent the
course which the malady may take, and which course seems
to be dependent upon the nature and quality of the infecting
agent itself. The inference, then, which may be derived
from the fact that a deficiency of fibrin exists in the blood of
persons afflicted with fever, is, that the tendency of the
cause of fever, a miasma, or whatever else it may be, is to
occasion a depreciation of the physiological standard of the
fibrin in the blood, and not that the deficiency is in itself the
exciting cause of fever.

Between this diminution in the normal proportion of the
fibrin and the various hemorrhages, which are so often
observed to complicate fevers of all kinds, a co-relation
doubtless exists, although the precise manner in which this
deficiency leads to such a frequent recurrence of hemorrhage
is not clearly understood, and the only way in which this can
be explained is by the supposition that in fevers from the
cause assigned, viz. the small quantity of fibrin, the solids
generally, and the blood-vessels in particular, lose a portion
of their solidity, and readily give way to the force of the fluid
contained within them.

THE BLOOD. 97

The hemorrhages referred to are frequently observed in
small-pox, in which the blood is effused into the pustules ; in
scarlatina, in which fluxes take place from various parts of
the body ; and in typhus, in which we have frequent buccal
hemorrhages, and the formation of petechias.

Cotemporaneous with this diminution in the amount of
fibrin, we do not find that any other element of the blood is
constantly affected, although it occasionally happens that the
red globules are in excess.

The clot in typhus, in which, of course, the deficiency of
fibrin is considerable, is large, filling almost the entire of the
vessel which contains it ; is soft, being readily broken up on
the slightest touch ; it is flat, and ill-defined, and the serum
in which it floats is of a reddish colour.

The flat form and softness of the clot is to be explained by
reference to the diminished amount of fibrin, while its great
size is accounted for by the imperfect expression of the serum
from the crassamentum, as well by the fact that the red
corpuscular element of the blood exists usually in its normal
proportion, and is not unfrequently found to be even in
excess.

The important distinction which exists between symp-
tomatic or organic fevers, and idiopathic or non-organic
fevers, is very essential to be borne in mind, for in the
former no such deficiency of the fibrin exists as we have seen
to belong to the latter ; the blood in inflammatory affections^
as will be shown hereafter, exhibiting a state of its spon-
taneously coagulable element the very reverse of that which
belongs to the blood of idiopathic febrile disorders. It must
also be recollected, that an idiopathic fever may, during its pro-
gress, become complicated with organic lesion, a circumstance
which would affect materially the amount of fibrin in the
blood, its effect being to increase the "proportion of that con-
stituent.

i 3

98 ORGANISED FLUIDS.

Increase in the Amount of Fibrin in Inflammatory Affections,
as in Pneumonia, Pleuritis, Peritonitis, Acute Rheuma-
tism, Sfc.

While in the class of febrile disorders, of which we have
just spoken, a deficiency of the fibrin in the blood exists, in
another series of affections, the inflammatory, this element
is found to be in excess. To constitute an inflammation,
however, two concurrent circumstances are required; it is
not alone necessary that the proportion of the fibrin should
be increased, but also that an organic lesion should have
occurred, these two pathological alterations bearing a close
and constant relation with each other.

Since, then, the spontaneously coagulable element of the
blood in the one class of disorders, viz. fevers, is deficient,
while in the other class, inflammations, it is superabundant,
it follows that the specific cause which gives origin to these
two orders of maladies operates in two opposite directions ;
its tendency in the one being to diminish, and in the other to
augment the quantity of fibrin.

The law of the increase in the quantity of fibrin in inflam-
matory disorders manifests itself under very remarkable
circumstances ; such, indeed, as one would imagine to be but
little favourable to its manifestation : thus, in the case of an
inflammation supervening on typhus, in which we have seen
that the normal scale of fibrin undergoes a depression, a dis-
position to the augmentation of that scale will become
apparent. In the example of typhus complicated with local
lesion, we have two forces in operation ; the tendency of one
of which is to diminish the amount of fibrin, and of the other to
increase that amount ; and the result of which forces ope-
rating at the same time is the production of a mean effect.

The proportion of fibrin in man in a state of health is
estimated at 3 parts in every 1000 of the blood. In a case
of inflammation occurring in the course of typhus, the scale
was found to be 5^ in persons affected with chlorosis, in
which we have seen that it is the globular element of the
blood which is deficient, and attacked with capillary bron-

THE BLOOD. 99

chitis, acute articular rheumatism, erysipelas, and pneumonia,
the proportion varied from 6 to 7 and 8 ; in acute inflamma-
tions occurring in healthy individuals, it oscillated between 6
and 8 ; and in a less number of cases between 7 and 10.
The highest scale recorded by M. Andral is 10 : and this
was met with only in pneumonia, and acute rheumatism,
while the lowest was only 4 : this scale borders upon that
which is regarded as normal, and is encountered only in
sub-acute inflammations.

It is not merely, however, in pure and extensive cases of
inflammation that the proportion of fibrin in the blood
becomes augmented, for we find it also increased in every
organic affection which is accompanied by even a slight
degree of inflammation : thus in phthisis, at the period of
the elimination of the tubercle, as well as in cancer, in which
there is inflammation of those portions of the organs, the seat
of the disease which immediately surround the tuberculous,
or cancerous deposit, we have also an increased amount of
fibrin in the blood. This increase, even in the last periods of
the disorder in phthisis, rarely exceeds 5 parts in the 1000.
The blood in consumption exhibits then not merely an excess
of fibrin, but also a depreciation in the proportion of its red
element to the extent shown under the heading Ancemia.

There is one condition of the system compatible with a
state of health, under which also the proportion of the fibrin
in the blood is augmented, and that is gestation. It is stated,
however, by M. Andral, that this increase manifests itself
only in the three last months of pregnancy, previously to
which the scale of the fibrin is found to be slightly depre~
ciated. This augmentation goes on increasing from the sixth
to the ninth month, and is greatest at the completion of the
term of utero-gestation, which fact offers a satisfactory
explanation of the reason of the liability to inflammatory
attacks on the part of women recently delivered. The con-
dition of the blood, therefore, in the last periods of pregnancy
is allied to that state of the vital fluid which is especially
indicative of the existence in the system of an inflammation.

The characters presented by the clot in inflammation are

i 4

100 ORGANISED FLUIDS.

almost the reverse of those which distinguish it in fevers.
It is of moderate size, of firm texture, frequently cupped, and
its surface usually covered with the buffy coating of a
variable thickness. The theory of the formation of this
peculiar layer has already been entered into, and the various
circumstances under which it has been encountered have now
been noticed ; we have seen that it occurs in two very
different states of the system, that it is present on the clot of
blood abstracted in anaemic conditions, as well as on that
formed in blood withdrawn in inflammatory states ; in the
first of these there is, in comparison with the red corpuscles,
a relative increase in the proportion of the fibrin, and in the
second, a positive augmentation of that important element of
the blood.

The fact of the existence of a superabundance of fibrin in
the blood in inflammatory states may be in some measure
inferred from the circumstance of the escape in inflammation
of a portion of its fibrin, and which doubtless is attended
with a certain degree of relief to the organ affected. In
many cases, however, it is not alone the fibrin which escapes,
and which is liable to become organized, but also the other
constituents of the blood, its red and white corpuscular ele-
ment, (the latter probably constituting the pus which in
certain severe cases is met with,) and the serum ; these con-
stituents, however, are not susceptible of organization, and are,
where recovery takes place, removed from the situation of
their effusion by absorption.

The discovery of the fact, that in inflammatory disorders
an excess of fibrin is formed, explains the exact manner in
which blood-letting proves so serviceable, viz. by removing
from the system directly a portion of its superabundant
fibrin ; so powerful, however, is the cause which determines
the formation of this excess of fibrin, that in spite of the
most energetic and frequent use of the lancet, the scale of
that element of the blood will frequently, and indeed does
generally, ascend.

THE BLOOD. 101

Condition of the Blood in Hemorrhages.

Reference has been made to the frequent occurrence of
hemorrhages in two very distinct classes of disorders, the
plethoric, and the febrile. In the first, we have seen that it
is the red element of the blood which is absolutely in excess
over the other constituents of that fluid, while, in the second,
it is the fibrin which is deficient, the globules being un-
affected, and existing usually in their normal proportion.
Thus, relatively to the fibrin in both series of affections, the
globules are always in excess, in reference to the first series,
the plethoric, being absolutely so, and to the latter, relatively
superabundant.

While it is this excess of the red globules which probably
determines the occurrence of hemorrhages, the nature and
degree of these losses of blood are modified by the amount of
fibrin which that fluid contains. Thus the character of the
hemorrhages occurring in plethoric individuals is very differ-
ent from that encountered in persons labouring under fever
in most of its forms ; in the first, we have copious epistaxes and
the effusion of blood into the substance of the brain, consti-
tuting sanguineous apoplexy ; in the second, almost any tissue
of the body may be the seat of the effusion ; the blood may
escape from the nose, the gums, the throat, or the bowels, or
it may be poured out beneath the skin in patches, constitu-
ting petechia3, which we meet with so frequently in severe
cases of typhus, and in scurvy. The hemorrhages to which
the plethoric are liable are for the most part salutary, while
those which take place in fevers are as generally prejudicial.
The treatment to be adopted in the two cases is very differ-
ent ; in the one it may be necessary to have recourse to vene-
section, with the view of lessening the scale of the red glo-
bules, and in the other such a mode of proceeding would in
all probability be fatal, the object in it being to restore to
the blood its normal proportion of fibrin.

The distinction which has here been dwelt upon between
the hemorrhages to which the plethoric arc exposed, and
those to which the system is obnoxious in febrile disorders at

102 ORGANISED FLUIDS.

an advanced period of their attack, corresponds with the
division of hemorrages into active and passive ; the former, or
sthenic type, denoting the active, and the latter, or asthenic,
the passive hemorrhages.

In disorders in which usually we have no excess of the red
globules, but in which the fibrin invariably exceeds its usual
quantity, as the inflammatory, and in affections in which the
red element is constantly deficient, but in which the fibrin
retains its proper proportion, as in anaemic states, and es-
pecially chlorosis, we find that hemorrhages are of very
rare occurrence, and hence again we are led to recognise the
accuracy of the statement, that the essential conditions for
the occurrence of hemorrhages are an excess of the red cor-
puscles, as well as in certain cases a deficiency of the spon-
taneously coagulable element of the blood, viz. the fibrin.

Between the condition of the blood, in which there is a
deficiency of fibrin, as in most fevers, and that state of the
system which occupied so much of the attention of the
ancient humeral pathologist, and which has been denominated
the putrid, an exact identity exists, and the greater the
depression in the scale of the fibrin, the more manifest does
the putridity become. While the blood is still circulating
within its vessels, we can scarcely conceive of its becoming
putrid ; nevertheless, so great in some cases is the deficiency
of fibrin, and so proportionate the consequent tendency to
putridity, that even during life certain symptoms indicative
of this condition become manifest, as the extreme prostration
of the strength, the foetor which belongs to all the ex-
cretions, and the vital principle having escaped, the external
signs of decomposition almost immediately appear.

The characters of the blood in hemorrhages scarcely differ
from those which we have pointed out as belonging to it in
fevers ; from the small quantity of fibrin, and the excess of
red globules, we find that the clot is large, ill-formed, very soft,
and never covered with the buffy coating, and that finally, in
a very short time, it undergoes almost entire dissolution, the
only trace of solid matter in the blood consisting of a few
shreds of fibrin.

THE BLOOD. 103

There is one disease, viz. scurvy, in which a condition of
the blood, as regards its fibrin, exists analogous to that which
characterises fevers, and in which also the same tendency to
repeated hemorrhages and to the formation of petechia?
belongs, as is witnessed in fevers.

It is a question for consideration whether the deficiency of
the fibrin referred to is the real cause of the proneness of the
blood to decomposition and dissolution ; and whether, if this
be the case, there is not some other prior cause which leads
to and regulates the extent of the diminution of the physio-
logical standard of the fibrin.

The experiments of Majendie show that the mixture of
certain alkaline substances with the blood not merely preserve
it in a fluid state, but restore to it the fluid form, even after
it has once coagulated. M. Majendie injected into the veins
of living animals a certain quantity of a concentrated solution
of the subcarbonate of soda, and found that in the dead
bodies of these animals the blood was almost entirely in a
fluid state, and that even during life they presented many of
the symptoms which are acknowledged to denote a state of
dissolution of the blood.

The alkaline condition of the blood in scurvy, in which
the proneness to hemorrhage is so great, is well known.

A fluid state of the blood is said to exist in those who
have died from the bite of serpents, and it is most probable
that in like manner the effect of the imbibition of a poisonous
miasma is to cause the blood to retain its fluidity.

The deplorable effects which sometimes ensue from a dis-
section-wound are most probably due to the entrance into
the blood of a poisonous matter, and in fatal cases we have
all the signs indicative of a dissolution of the blood.

It is likewise asserted, that any violent impression made
on the nervous system, either through the influence of some
strong moral emotion, or as the result of a blow, especially
on the pit of the stomach, an electric shock, as of lightning,
retards, or altogether prevents, the coagulation of the blood,
while at the same time it destroys life. ° That the same effect
is likewise produced, though in a manner less obvious and

104 ORGANISED FLUIDS.

less sudden, by the slow and. continued operation of any
cause which depresses the power of the nervous influence, so
as at length to effect the health prejudicially, cannot be
doubted.

The proneness of children to hemorrhages, their liability
to febrile disorders, and the difficulty of restraining the
bleeding which flows from any breach of continuity which
the skin may have suffered, especially that of a leech-bite, in
infants, are well known. The state of the blood in children
is not commented upon by the talented authors to whom we
have had such frequent occasion to refer in their important
pathological essay on the blood : it is most probable, however,
that while its globular element is somewhat in excess, that
in fibrin it is equally deficient.

With one other remark we will bring this short chapter
on hemorrhage to a conclusion, and proceed in the next
place to consider the effect produced upon the economy by
the deficiency of another element of the blood. The statisti-
cal and historical details of epidemics clearly prove that those
dire forms of disease, of which extensive and alarming
hemorrhages were such frequent complications, have in these
latter times become much more rare. This happy result is
doubtless due to the advances made in the arts and sciences,
and to their more extensive application in the improvement
of the hygienic condition of mankind.

Decrease in the Normal Proportion of Albumen.

It is now generally known, that the majority of cases of
dropsy depend upon a pathological alteration of some solid
organ of the body, as the heart and the liver ; most persons
are also aware of the fact that other cases of dropsy occur,
which do not arise from any such morbid organic condition,
but have their origin, according to MM. Andral and Ga-
varret, in a pathological^degeneration of one of the elemental
constituents of the blood.

In the dropsy which attends the advanced stages of the
affection known by the name of Bright's disease of the kid-

THE BLOOD. 105

ney, in that which supervenes upon scarlatina, in hydropsies
arising from insufficient and improper diet, as well as in
those which occasionally follow suddenly suppressed per-
spiration, it has been observed that the urine is always
albuminous, and the writers just mentioned have ascertained
the existence of a fact which stands in close relation with the
albuminous excess in the urine in the instances enumerated,
viz. that the blood is itself in these cases, on the contrary,
deficient in albumen. The knowledge of these two facts,
therefore, and the observation that their occurrence is so
generally associated with dropsical effusion, has led MM.
Andral and Gavarret to entertain the opinion that a close
connection exists between the deficiency of albumen in the
blood, and the forms of dropsy alluded to, and which is pro-
bably that of cause and effect.

In speaking of non- organic dropsies it has, until recently,
been conceived sufficient to say that they depended as a
cause upon impoverishment of the blood ; but this expression
we now know to be vague, inasmuch as it does not convey
any exact notion of the real changes which the blood may
have undergone: we have seen that the blood may be rich in
its red globules or in its fibrin, and also that it may be poor
in these elements in almost every proportion and degree.
Let us see whether a deficiency of either of the two con-
stituents just named predisposes to dropsies. In anaemic
states, and in chlorosis especially, we have an impoverished
state of the blood, and in these we know that it is the red
corpuscles which are deficient; and yet daily experience shows
us that dropsy in such states, and particularly in chlorosis,
even in its most severe forms, is a very rare termination.
In febrile disorders again, we have, for the most part, an
impoverished condition of the blood, arising from the de-
pression in the scale of the fibrin, and yet of these we do not
find dropsical effusion to be by any means a frequent result.

It is not excess of water in the blood which gives rise to
dropsy, for, if that were the case, then would it frequently
occur in the disorder to which we have" referred, chlorosis, in

106 ORGANISED FLUIDS.

which a greater proportion of water than is normal exists in
the blood.

The causes of impoverishment of the blood enumerated
therefore do not act as exciting causes of dropsy : there
remains but one other element of the blood, the albumen, for
our consideration, and this we have seen to be constantly
deficient in the blood in certain forms of dropsy, and we are
therefore constrained to adopt the conclusion that this de-
preciation in the scale of the albumen is intimately associated
with the occurrence of those forms.

It does not appear, according to M. Andral, that the
albumen can undergo a spontaneous depreciation in the blood,
similar to that of which we have seen that the red globules
and the fibrin are susceptible ; this, if correct, is very re-
markable, and hence it would follow that whenever a de-
ficiency of the albumen of the blood exists, invariably, at the
same time, the urine would be found to be albuminous, pro-
vided always that no dropsical effusion existed, the effect of
some organic malady.

In most organic dropsies the diseased organs act as exciting
causes of the serous effusion by the mechanical impediment
which their altered structure and enlarged size present to
the circulation in the vessels, and which, therefore, relieve
themselves by permitting the escape of a portion of their
contents. In Bright 's disease, although the kidney is
affected, that organ does not concur in the formation of the
dropsy, except in a manner altogether indirect, and to such
an extent only as that the pathological alteration which its
substance undergoes is of such a nature as to afford greater
facility to the passage of the albumen through it.

The serosity effused in cases of dropsy is not identical in
its constitution with the serum of the blood; it contains
usually far less of the inorganic constituents which are held
in solution in healthy serum, as well as a far less proportion
of albumen than that which belongs to serum in its normal
state. The physiological standard of the albumen in the
blood is eighty in every thousand parts ; in sixteen cases in
which the serous effusion was analysed by M. Andral the

THE BLOOD. 107

scale was found to oscillate between 48 and 4, these two
numbers representing the highest and the lowest proportions.
In six cases of hydrocele, the amount of albumen was, as
represented by the following figures, 59, 55 ; two of 51 ; 49,
35. It should be remarked that none of these analyses refer
to cases of dropsy connected with excess of albumen in the
urine. It would be interesting to ascertain the amount of
the albuminous element contained in the serum effused in
such cases.

MM. Andral and Gavarret state that they did not find
that either the cause of the hydropsy, or its seat, excited any
influence over the quantity of albumen of the effused serum ;
but they remarked that the amount did in some degree
depend upon the condition of the constitution, and that the
more robust its state the greater the proportion of the
albumen : in this way the higher scale exhibited in the six
cases of hydrocele may be accounted for, their occurring in
persons all of whom were young and strong ; and thus, also,
the great depression of that scale may be explained in those
whose constitutions have been weakened by repeated
tappings.

Two explanations may be given of the reason why blood
less rich than ordinary in albumen should give rise to serous
effusion. The first is, that the abstraction of the albumen
may alter the density of the serum, and thus permit more
readily its escape through the walls of the vessels ; the second
is, that blood deprived of its albumen becomes less yielding,
and so glides less easily along the walls of the capillary vessels,
thus occasioning in them an obstruction to the circulation and
consequent effusion of serum. Of these explanations the
former is, perhaps, the more probable.

The proportion of water in all serous effusion is, of course,
considerable, and is greatest in those cases in which there is
least albumen. The mean proportion of water in the serum
of the blood is 790 in 1000 parts; in the fluid of dropsies
the highest scale hitherto observed is 986, and the lowest
930.

The fluid effused in burns and scalds, and as the result of

108 OKGANISED FLUIDS.

the application of a blister, and which are always preceded
by some degree of inflammation, are also rich in albumen.
The very curious observation is made by M. Andral, that in
cases where dropsical effusion exists in more than one situa-
tion in the same individual, that in each locality the fluid
effused may exhibit a very different proportion of albumen.
Thus, in a woman attacked with an organic affection of the
heart, there were thirty parts of albumen in the fluid of the
pericardium, while there were but four parts in the serosity
of the cellular tissue of the inferior extremities.

In having thus ascertained the different modifications in
quantity which the three great elements of the blood may
undergo, the globules, the fibrin, and the albumen, it yet
must be confessed that the pathological history of the blood
is still very far from being rendered complete. It is more
than probable that rigorous chemical analysis will disclose
the fact that the several extractive as well as inorganic sub-
stances which exist in the blood vary greatly in amount in
the numerous disorders to which the human body is liable.
From the great quantity of these substances which are found
in the urine, it would appear that the grand purpose fulfilled
in the economy by this excretion is that of regulating their
amount in the blood, and of reducing it to a standard con-
sistent with a physiological condition of the system.

Into this branch of the pathology of the blood inquirers
have as yet scarcely entered ; and there can be no doubt but
that investigations instituted in this direction would be
attended by the development of many important facts.

Therapeutical Considerations.

The practical value to be attached to the various particulars
related in the preceding pages on the pathology of the blood,
is so obvious that it needs not to be illustrated at any great
length.

The knowledge of the particular element of the blood
which in any state of the system or disease may be affected,
inasmuch as it discloses the chief cause of such condition or

THE BLOOD. 109

malady, furnishes the practitioner with an unerring principle
upon which the nature and the extent of the treatment adopted
should be founded. Hitherto, the chief guides in practice have
been based upon experience and clinical observation ; both,
doubtless, of high importance ; but still not in many cases
sufficient to detect the cause of a malady, and therefore not
in themselves equal to the determination of the exact line of
treatment to be pursued, or of the extent to which that line
should be followed.

We are now not merely acquainted with the bare fact,
derived from experience, that in anemic conditions of the
system the different preparations of iron are useful, but we
have dived deeper into the mysteries of organization, and we
now know the reason why iron is necessarily so beneficial in
the disorders to which such a condition of the system gives
rise.

The precise objects to be held in view, in the employment
of every remedial appliance in the treatment of inflammatory
affections and fevers, we are now acquainted with ; and by
our present knowledge we can judge of the propriety and
extent of usefulness of the various plans of treatment which
in times past have been had recourse to, or which still
continue to be applied ; and we can detect the reason why one
particular mode of treatment should have been more success-
ful than another.

Bequerel and Rodier's Pathological Researches on the
Blood,

MM. Bequerel and Rodier* have traversed the same
ground as MM. Andral and Gavarret in reference to the
blood, which they have examined both in health and disease.

These authors confirm many of the more important results
obtained by antecedent observers, but question the accuracy
of some of those results, and add new facts in relation to the
normal and abnormal composition of the blood.

* Gazette Medicale de Paris, 1844. Recherches sur la Composition
du Sang dans 1'etat de Sante et dans 1'etat de Maladie.

K

110 ORGANISED FLUIDS.

The results which confirm those which had been previously
obtained are the following : —

1. The augmentation of the fibrin in inflammations, the
establishment of which fact is especially due to MM. Andral
and Gavarret.

2. The diminution of the globules in chlorosis, in the con-
dition denominated the anaemic, and under the influence of
fasting ; a fact stated by M. Lecanu, and confirmed by MM.
Andral and Gavarret.

3. The diminution of the globules from haemorrhages and
anterior bleedings ; a result which, signalised for the first
time by MM. Prevost and Dumas, has been confirmed in
the numerous analyses of MM. Andral and Gavarret.

4. The little influence of bleedings upon the scale of the
fibrin.

5. The diminution of the albumen in the malady of Bright
as indicated by Gregory, Rostock, Christison, Andral, and
Gavarret.

Of the results which differ from, and perhaps invalidate
those of antecedent observers, the principal are, —

1. That the scale y^o giyen as representing the mean of
the globules in a state of health is too low, and is not the
same in man and in woman.

2. That the scale representing the fibrin as TO%O is too
high.

3. That there is not alone in plethora an augmentation of
the globules, as signalised by M. Lecanu, and as has been
admitted by MM. Andral and Gavarret.

4. That the scale of the globules is not preserved in its
normal proportion in the majority of acute affections.

5. That the depression in the scale of the fibrin in severe
fevers is but little constant.

The more important of the new results are the follow-
ing :—

1. That the scale 141 expresses the mean number of the
globules in man in a state of health, and that of 127 repre-
sents the average in woman.

2. That the ordinary scale of the fibrin is 2-2, and the
mean 3.

THE BLOOD. Ill

3. That in plethora there is an augmentation of the
quantity of the mass of the blood.

4. That the influence of disease upon the composition of
the blood is to occasion from the commencement a diminu-
tion in the proportion of the globules, and this diminution
continuing during the progress of the malady, ends in the
production of the ansemic condition of the system.

5. That there is an absolute excess of fibrin in many cases
of chlorosis and of pregnancy, and that its diminution is far
less constant than has been considered in fevers.

6. That the albumen of the blood diminishes under the
influence of illness ; that it is more considerable in inflamma-
tions ; and further, that the diminution is in direct relation
with the augmented amount of fibrin, which it may be
presumed is formed at the expense of the albumen; that
there is not only a very great diminution of albumen in the
malady of Bright, but also in certain affections of the heart,
accompanied by dropsy, and in certain severe forms of puer-
peral fever.

7. That the amount of cholesterine and of acid fats in-
creases as we advance in age ; but that this increase is not
felt until from the fortieth to the fiftieth year ; that it is also
found in augmented quantities in the blood in constipated
states of the system, and in jaundice, with retention of the
bile and decoloration of the fasces. *

The Blood in the Menstrual Fluid.

The menstrual fluid contains all the elements of the blood,
especially the red and white corpuscles, and it is therefore in
the same manner as the blood itself susceptible of circulation.
In addition to the constituents of the blood, we find the
uterine discharge to be composed of vaginal mucus, mixed up
with numerous epithetral scales, which it has acquired in its
passage along the vagina.

* The above remarks are abbreviated from an abstract of MM. Bequerel
and Rodier's work on the blood, by MM. Millor and Reiset, contained
in the " Annuaire de Chimie," for 1846.

K 2

112 ORGANISED FLUIDS.

Unlike, however, in one respect the blood itself, which in a
state of health is alkaline, the menstrual fluid is acid, its
acidity arising from its admixture with the vaginal secretion.

Transfusion of the Blood.

It has been stated, and the statement is most probably
correct, that between the size of the blood corpuscles and
that of the capillaries of the same animal, an exact relation
exists, and it is by reference to this fact that the fatal effects
which have so often ensued, from the transfusion of the
blood of one animal into the vessels of another have been
apparently so satisfactorily explained. The little vessels, it
has been said, are too small to admit the larger globules of
the new blood ; a mechanical impediment is thus offered to
the circulation of the blood in the capillaries, which stagnates
in them, giving rise to constitutional disturbance, and ultimately
to death. This explanation, plausible as it appears, has been
shown by recent experiments to be erroneous, and that the
true cause of the fatality which has so often attended the
operation of transfusion, depends upon the difference which
exists in the qualities of the fibrin in the blood of two different
animals, or even of two distinct individuals : this is shown by
the fact that the transfusion of blood deprived of its fibrin
is never followed by the serious results to which reference
has been made. Notwithstanding this fact, it is yet very
evident that if the blood of an animal, the corpuscles of
which are much larger than the human blood disc, and at the
same time are of a different form and structure, such as for
instance those of some birds, be introduced into the vessels
of man, a very serious and probably fatal mechanical im-
pediment would be presented to their circulation through the
capillaries. Blood corpuscles of a circular form, and but
little larger than those of man, might indeed make their way
through the vessels in consequence of the plastic nature of
the globuline which composes them.

The new globules thrown into this system by the operation
of transfusion, although they would circulate for a time with

THE BLOOD. 113

the other blood globules, would doubtless all become destroyed
and removed in the course of a few days, and this especially
if the blood corpuscles were different from those of the
animal from which the transfusion had been practised.

The Blood in an Ecchymosis.

When a part is bruised to such an extent as to occasion
the rupture of the minute capillaries and vessels contained in
it, blood is effused constituting an ecchymosis. The same
effect sometimes takes place, not as the result of the applica-
tion of external violence, but from disease, the solid tissues
and that of the vessels especially giving way through debility,
and permitting the escape of their contents, as occurs in
malignant and putrid fever, in Purpura H&rnorrhagica, in
scurvy, and in bed-sores.

If a portion of the effused blood be removed from the
bruise and examined microscopically, the globules will be
observed to be wrinkled and irregular in form, corresponding
with and depending upon internal changes in the condition
of the blood effused, and which are indicative of the occurrence
of decomposition ; certain external appearances will be noticed,
the skin will appear mottled, different hues of black, green,
and yellow being intermixed and varying in intensity until
the period of their total disappearance.

The phenomena of decomposition precede the disappearance
of the red corpuscles which are removed from the seat of
injury, and are returned to the circulation in a state of solu-
tion. Now were the opinion true that the blood corpuscles
are applied directly to the formation of new tissue, a very
different result to the decomposition and solution of the
globules, to which we have referred, would be anticipated,
and we should expect to find that the extravasated blood had
njiven rise to an adventitious and organised product, an event
to which ecchymoses never lead.

114 ORGANISED FLUIDS.

The Effects of certain remedial Agents upon the Constitution
and Form of the Blood Corpuscle.

We have seen, in the remarks on the effects of re-agents,
that many solutions and substances applied to the corpuscles,
after their abstraction from the system, modify their form,
appearance, and properties.

Thus we have seen that in water, as in any other analogous
liquids of less specific gravity than the serum of the blood,
that the corpuscles lose their normal form and become
circular, their colouring matter passing at the same time into
the fluid.

We have likewise observed that in liquids of an opposite
character, and the density of which equals or exceeds that
of the blood, their form is preserved and even rendered
flatter than ordinary : thus their shape is well maintained or
but slightly affected in the white of egg, urine, the saliva,
concentrated solutions of the chlorides of sodium, and of
ammonium, the carbonates of potassa and ammonia, and of
sugar.

The blood corpuscles likewise preserve their form in the
solutions of other substances, the density of which would not
appear to be very great, but which are possessed of very
strong and decided properties ; thus they maintain their shape
well in a solution of iodine, and become but slightly con-
tracted in those of chloride of sodium, while, according to
Henle, the primitive flattened form of corpuscles swollen by
the imbibition of water may be restored to them by the
application of the concentrated saline solutions.

Nitric acid produces an irregular contraction of the cor-
puscles. It has been remarked in like manner that a host of
substances affect the colour of the corpuscles.

But it is not alone the form and colour of the blood cor-
puscles which are affected by the contact of re-agents ; their
properties also are modified by them.

Thus the corpuscles to which iodine has been added are so
hardened by it that they experience little or no change of
form in the addition of water.

THE BLOOD. 1 15

The same is the case, according to Henle, after treatment
by nitric acid.

The acetic, and one or two other acids, it is known, dis-
solve the corpuscles of the mammalia without residue, but
leave almost unaffected the granular nucleus contained in the
red blood corpuscles of the oviparous vertebrata.

The above are some of the more striking effects produced
in the form, colour, and constitution of the blood corpuscles
out of the system, on their treatment by reagents.

Now there is evidence to show that blood corpuscles, while
they are circulating in the body, are likewise affected,
although to an extent less considerable, and therefore less
appreciable, by substances and solutions introduced into the
system through the medium of the lungs or of the stomach.

Thus we know that the blood changes its colour in the
lungs and during its circulation through the capillaries, and
that these changes are dependant upon the relative amount
of oxygen and of carbon contained in the corpuscles.

Again, it has been asserted by Schultz, as already men-
tioned, that accompanying these alterations of colour there
are also changes of form, the corpuscles becoming more or
less circular in carbonic acid and hydrogen gases, and flat in
oxygen gas. This assertion I have myself failed to verify.

It cannot be doubted, however, but that the form of the
red blood corpuscle must vary according to the variations of
density experienced by the liquor sanguinis, and further but
little hesitation can be felt in admitting that this alteration
of density does really attend upon particular conditions of
the system ; thus, in inflammatory affections, the liquor
sanguinis is assuredly more dense than it is in states in which
in opposite condition of the blood exists, that in which the
watery element abounds.

After very copious imbibition of water also, it can scarcely
be doubted but that the density of the blood is lessened, and
that the red corpuscles are modified in shape in conse-
quence.

Thus much for colour and form ;. let us see if we are
acquainted with any fact capable of proving that the con-

L

116 ORGANISED FLUIDS.

stitution of red blood corpuscles is also influenced by the
introduction into the stomach of remedial agents.

Schultz relates the fact that the corpuscles of the frog,
in the mouth of which during life iodine had been placed,
resisted for a longer time the action of water.* The truth of
this most interesting and important observation I have myself
verified.

The blood corpuscles of a frog, which was subjected to the
vapour of iodine, underwent no appreciable change of form
in water for nearly an hour during which they were ob-
served, a time more than sufficient to ensure the complete
change of shape and subsequent disintegration of the blood
discs of a frog not similarly treated.

It may be observed that in the case related, starch failed
to detect the presence of iodine, although this was set free
by previously dissolving the corpuscles by means of acetic acid.

After the relation of the above facts, it is evident that
remedial agents do affect in several important particulars the
blood corpuscles of the living animal, and it is further pro-
bable that a considerable proportion of their remedial influence
is dependant upon the nature and extent of their power in
modifying the red blood disc.

The importance of a Microscopic Examination of the Blood in
Criminal Cases.

In criminal cases it is sometimes a matter of the highest
importance to the furtherance of the ends of justice, that the
nature of certain stains, observed on the clothes of an accused
person, should be clearly ascertained.

The fact usually to be determined is, whether the stains in
question are those of blood or not, Now in the decision of
this important matter, the microscope comes to our aid in a
manner the most decisive and convincing.

If the stain be a blood stain, and if its examination be
properly conducted, the microscope will lead to the detection
in it of the blood corpuscles themselves both white and red.

* Das System der Circulation. Stuttgard, 1836. p. 19.

THE BLOOD. 117

The enquiry having been proceeded with thus far, and the
stain having been proved to be one formed by blood, it stu '
remains for decision, whether the blood thus detected is
human or not.

In the solution of this difficulty the microscope likewise
affords considerable assistance, and this of a kind which can
be obtained in no other way. Although by this instrument
we are not able to assert positively from an examination of
the blood stain itself, free from admixture with any other
organic material, that the blood is really human, we yet shall
have it in our power very frequently to declare the converse
fact, viz., that a certain blood stain is constituted of blood
which is not human, a particular on the knowledge of which
the life of an accused individual might depend.

Thus if we find that the blood globules are of a circular
form and destitute of nuclei, we may safely conclude that
they belong to an animal of the class Mammalia, although, at
the same time, we in all probability should not be able to
pronounce upon the name of the mammal itself; if, on the
contrary, the blood corpuscles are elliptical and provided with
a granular nucleus, we may be equally certain that they do
not appertain to that class, but either to the division of birds,
fishes, or reptiles. *

By the size also as well as the form of the corpuscles,
some idea of the animal from which the blood was derived
might be formed ; and if we cannot pronounce with certainty
upon this, we shall at all events, and at all times, be able to
go the length of affording negative evidence, and of asserting
that the corpuscles do not represent the blood of certain
animals which might be named, and a knowledge of which
fact might prove of extreme importance.

To show the valuable nature of the evidence which it is in
the power of a medical man who makes a right use of
tho microscope frequently to afford, in criminal inquiries,
we will suppose the following case.

* The only animals of the class Mammalia which have blood corpuscles
of an elliptical form, are those of the order Camelidce; they are, how-
ever, very small, and destitute of nuclei.

L 2

118 ORGANISED FLUIDS.

A person is apprehended on the suspicion of having been
concerned in a murder. On his clothes are observed certain
stains ; upon these he is questioned ; he admits that they are
blood stains, and states that he had been engaged in killing
a fowl, and that in this way his clothes had acquired the
marks. The stains are now submitted to microscopic ex-
amination ; the blood of which they are constituted is found
to belong to an animal of the class Mammalia, and not to that
of Aves ; discredit is thus thrown upon the party suspected,
fresh inquiries are instituted, fresh discoveries made, and the
end of all is the conviction of the accused of the crime
imputed.

But a third question presents itself, to which it is very
necessary that a satisfactory reply should be made, viz., did
the blood, of which the stain is constituted, flow from a living
or dead body ? This query we will proceed to answer.

If a vessel be opened during life, or even a few minutes
after death, the blood which issues from it in a fluid state
will quickly become solidified from the coagulation of the
fibrin.

But if, on the other hand, a vessel be opened some hours
after death, the fluid blood which escapes will not solidify
because it contains no fibrin, this element of the blood having
already become coagulated in the vessels of the body in which
it still remains.

Now this act of the solidification of the fibrin is deemed
by many to be a vital act, and to be the last manifestation of
life on the part of the blood.

It would appear, however, that the coagulation of the blood
should not be regarded as a vital act, seeing that blood which
has been kept fluid for some time by admixture with saline
salts will coagulate when largely diluted with water, and
also, that blood which has been frozen previous to coagulation
will undergo the process of solidification after it has been
rendered fluid again by thawing.*

* Dr. Polli has related a case in which the complete coagulation of the
blood did not take place until fifteen days after its abstraction. — Gaz-
zetta Medica di Milando, 1844.

THE BLOOD. 119

Presuming, then, that the coagulation of the blood is not
an act of vitality, the inference to be deduced from the
presence of coagulated fibrin in blood stains, in which the
corpuscles may be detected, is scarcely weakened thereby,
since the finding of such fibrin in such a situation, and in
connexion with the blood corpuscles, scarcely admits of a
rational and probable explanation of its occurrence being
given apart from the idea that the blood had issued from a
body either living or but just dead, and in which coagulation
of the fibrin in the vessels had not occurred.

The blood stains, therefore, which contain coagulated fibrin
in them, it is but little doubtful must have proceeded either
from a living individual, or from one but just dead ; while,
on the contrary, it is as little to be doubted, but that those
stains which do not contain solidified fibrin, must have
emanated from a body dead some hours, or from blood which
had already been deprived of its fibrin.

From the disposition and form also of the blood spots,
some idea can be formed as to whether the blood had sprit
out of a living body or not.

A few observations may now be made, first, on the length
of time after the formation of blood stains at which the
corpuscles can be detected ; and second, on the best mode of
proceeding in the examination of those stains.

From observations which I have made, it would not appear
that it is necessary that the blood stain should be recent. I
am inclined to think that the period scarcely admits of
limitation.

Thus in blood stains six months old, I have observed the
corpuscles presenting very nearly the form and appearance
proper to them when recently effused, and previous to their
becoming dried up.

In the blood of the frog, six months after its abstraction
from ' the animal, I have observed the corpuscles both red
and white, and in the former, the characteristic granular
nuclei with so much clearness, that it would have been an
cusy matter to have studied upon them the development of
blood corpuscles.

L 3

120 ORGANISED FLUIDS.

The observance of one precaution, at least, is necessary
for the successful exhibition of the microscopic characters of
blood stains.

Thus, water should never be applied to them, nor indeed
any other fluid, the density of which is less than that of the
serum of the blood, for all such liquids will occasion the
discharge of the colouring matter of the blood corpuscles and
an alteration of their form ; thus the circular but flattened
corpuscles of the Mammalia will assume a globular shape, as
will also the elliptical blood discs of birds, fishes, and rep-
tiles, one of the greatest points of difference between the
blood corpuscles of the former and latter classes being
thereby effaced.

Blood stains, therefore, should be moistened, previous to
examination, with some fluid, the density of which nearly
equals that of the liquor sanguinis ; and I have found the
albumen of the egg to preserve the form of the corpuscles
excellently well.

Failing, however, in detecting the blood corpuscles, a
result scarcely to be anticipated, assistance may be derived
from a toxicological examination of the blood.

The only tests peculiar to the blood are those which have
relation to the hrematine. This principle it would, however,
be difficult to obtain from blood stains in sufficient quantity
for the purposes of copious chemical analysis.

Nevertheless, corroborative evidence of the suspected cha-
racter of a stain might be obtained by its general chemical
analysis, and which should be treated as follows.

The stain should first be moistened with cold distilled
water, as much of the matter of it should then be removed as
possible, and placed in a test tube with an additional quantity
of water. This being agitated, the colouring material, if the
stain be a blood stain, will be dissolved by the water, imparting
to it a pinkish colour, while, provided the blood flowed from
the body during life, or at all events within a few minutes of
decease, suspended in the liquid, will be seen shreds of fibrin.

This solution, when heated to near the boiling point, will
become turbid, and deposit flakes of albumen.

THE BLOOD. 121

The same thing will occur when it is treated with nitrate
of silver or bichloride of mercury.

The addition of a strong acid or alkali turns the colouring
matter of a brown tint.

These results, however, are common to other mixtures of
animal substances in combination with colouring matter be-
sides the blood, and no one of them is perfectly characteristic.

It would therefore appear, that the microscope is capable
of revealing evidence much more satisfactory in reference to
the nature of blood stains, than that which it is possible to
derive from chemical examination.

Finally, it may be observed, that during the examination
of blood stains, other substances may be detected in con-
nexion with them, the presence of which would reveal not
merely their nature, but also the seat from which the blood
forming them had flowed ; thus some of the various forms of
epithelial cells and of hairs, may occasionally be encountered
in them.

We now bring to a conclusion this long article upon the
grand formative fluid of the system, the blood, and pass to
the consideration of other fluids of the economy, viz , pus
and mucus.

122 ORGANISED FLUIDS.

ART. III. MUCUS.

WE have seen that the blood consists of two parts, the one
fluid, the liquor sanguinis, the other solid, the globules ; the
same constitution belongs also to mucus as well as to some
other of the animal fluids, as for example, pus and milk.

Mucous globules find their analogue in the white corpuscles
of the blood, while the fluid portion of mucus resembles
closely the fibrin of the blood, fibrillating or resolving itself
into fibres in the same manner as the fibrin. From this fact
there can be no doubt but that the transparent or fluid con-
stituent of mucus is mainly composed of fibrin.

It is probable that the fluid portion is the only essential
constituent of mucus, and that the globules are connected
with it merely in an indirect and secondary manner, notwith-
standing that their presence is all but constant. The correct-
ness of this view is in some measure sustained by the fact,
observed first by M. Donne, that the mucus obtained from
the neck of the uterus, in young girls, is invariably free from
corpuscles.

It is with the solid particles of the mucus that we shall
be chiefly occupied, for they more properly enter into the
domain of the microscope ; the fluid element eludes to a great
extent the power of this instrument, and the detection of its
properties enters principally into the province of the chemist.

GENERAL CHARACTERS.

Healthy mucus, in its fluid state, is a transparent, viscid
and jelly like substance, which does not readily become pu-
trescent; in its dried condition, it assumes a dark appear-
ance, and a horny and semi-opaque texture ; in water it
swells up, re-acquiring most of the properties which charac-
terised it when recent. It sometimes exhibits an acid, and
sometimes an alkaline re-action, according to the exact struc-
ture of the mucous membrane by which the mucus is itself
secreted.

MUCUS. 123

Mucous membranes., therefore, as might be inferred from
the concluding passage of the preceding paragraph, do not all
present a constitution precisely similar the one to the other ;
and on their differences of organization a division of them
into three classes may be instituted, as has been pointed out
by M. Donne.

The first class of mucous membranes comprises those which
are contiguous to the outlets of the body, and which are to be
regarded as extensions of the skin, participating in all its
properties : thus the fluid secreted by this class of mucous
membranes manifests, like that of the skin, an acid re-action,
and the same epithelium which invests the latter belongs also
to the former ; in other respects the correspondence is like-
wise exhibited, the membranes under consideration manifest
the same sensibility, the same freedom from hemorrhage,
which characterise the skin ; they in like manner ulcerate less
readily, and are never furnished with the vibratile cilia3
which belong to the second class of mucous membranes, viz.
the true. This first described class of membranes may be
denominated false mucous membranes ; and as an example of
it the vagina may be cited.

The membranes which belong to the second class arc
situated more internally than the last, and have scarcely any
thing in common with those of the first class: the mucus
secreted by them constantly exhibits an alkaline re-action,
and the epithelium which invests them is of a totally dif-
ferent structure, the cells which constitute it being cuneiform,
and in some situations provided with numerous vibratile
cilisc : the general properties of this class of membranes are
also opposed to those of the previous division : thus they are
but little sensitive to the touch, are frequently the seat of
hemorrhages, and ulcerate with much facility. The mem-
branes of this class are to be considered as the true mucous
membranes, and that which lines the trachea and bronchi
may be instanced as the type of this class.

The third class is more artificial than the two preceding ;
the membranes which it comprises exhibit in a greater or
less degree the characters of each of the divisions already

124 ORGANISED FLUIDS.

described, between which they are intermediate in situation,
as in structure, participating in the characters of the false or
true raucous membranes more or less, according to the pre-
ponderance of either of these classes. The membranes of
this division may be called mixed, and those of the mouth
and nose may be regarded as typical.

Now, however useful for the purposes of description the
above classification may be, it must still be remembered that
it is, to a very considerable degree, arbitrary ; the membranes
which we have described as false mucous membranes belong
rather to the skin than to true mucous structure, while the
mixed membranes exhibit only the gradual transition from
the external skin to the internal true mucous membrane:
thus, strictly speaking, there is but one class of mucous mem-
branes, and that the true. Corresponding with the differ-
ences which have been pointed out as characteristic of the
three classes of mucous membranes, there are others apper-
taining to the mucus secreted by each of these orders of
membranes, and which arise from their diversity of structure,
and which serve to distinguish the mucus of the one class
from that of each of the other classes.

1st. The mucus proceeding from true mucous membranes
is viscous and alkaline, containing, imbedded in its substance,
numerous spherical, semi-transparent, and granular corpuscles
of about the ^Vo of an inch in diameter (see Plate XL
Jig. 1.)*, having a somewhat broken outline, as well as oc-
casionally epithelial cells more or less cuneiform, and some-
times provided with cilia?. These corpuscles are for the most
part nucleated, they are not at first soluble in water, but
swell up in that fluid to two or three times their former
dimensions (see Plate ~KL.jig. 3.), and, like the white globules
of the blood to which they bear the closest possible resem-

* A law having reference to size, and the importance of which will be
hereafter demonstrated, may here be announced. It is that the several
structures, especially the corpuscular ones, entering into the composition
of the animal organization, bear a near relation of size the one to the
other.

MUCUS. 125

blance, they contract somewhat under the influence of acetic
acid, and are soluble in a concentrated solution of ammonia.

2nd. The mucus secreted by false mucous membranes, or
those which are analogous to the skin, although more or less
thick, does not admit of being drawn out into threads, is acid,
and in place of spherical globules contains numerous scales
of epithelium which differ from true mucous globules in
their much larger size, flattened form, and in their irregular
and very frequently oval outline : these scales, like the true
mucous corpuscles, are nucleated, and the nuclei comport
themselves with chemical reagents, in the same manner as
the globules of mucus,

Example : — the mucus of the vagina. (See Plate XII.

Jig- 10

3rd. The mucus proceeding from the mixed or transition
membranes is sometimes acid, sometimes alkaline, at others
neutral, and contains a mixture of true mucus corpuscles and
epithelial scales, the relative proportion of each of which
varies according to the exact structure of the membrane by
which it is furnished. (See Plate XII. fig. 2.)

These divisions of the mucus into three different kinds,
although to some extent artificial as already observed, are yet
not without their practical utility.

The microscopical and chemical characters of mucus like-
wise vary much, not merely according to the general organi-
zation of the membrane by which it is secreted, but also in
accordance with the condition of the membrane itself, with
the degree of irritation or inflammation to which it is sub-
ject, and with the precise nature of the disorder by which
it is affected ; thus, sometimes, the mucus secreted by the
lining membrane of the nose is thin and watery, the fluid
element being in excess, and at others it is thick and opaque,
its solid globular constituents superabounding. Its colour
also as well as its consistence exhibits various modifications
in pathological states, being sometimes white, greenish or
yellow.

The description of the different forms of epithelial cells
alluded to, and which are occasionally encountered in the

126 ORGANISED FLUIDS.

mucus mixed up with true mucous corpuscles, belongs not to
the fluids, and will be given in detail under the head of
Epithelium, in that division of the work which is devoted to
the consideration of the solids of the human body; the
structure, form, size, properties and nature of the true
mucous corpuscles may here be described with advantage.

Mucous CORPUSCLES.

Structure. — The mucous corpuscles, which are colourless
and mostly of a circular form, are each constituted of a
.nucleus, an envelope, an intervening fluid substance, and
numerous granules, which are diffused generally throughout
the entire of the corpuscles, being contained within the cavity
of the nucleus, in the space between this and the outer enve-
lope, and, lastly, in the substance of the envelope itself; this
arrangement imparting a granular texture to the entire cor-
puscle. (See Plate XL)

The nucleus, like the corpuscle itself, is a circular body of
about one-third, or one-fourth its size: it sometimes occu-
pies a central, but very frequently an eccentric position in
the mucous globule : it is not at all times visible, although
very generally so, without the addition of re-agents, the best
being water and acetic acid.

The addition of water to mucous corpuscles discloses, in
the majority of them, but a single nucleus (see Plate XI.
Jig. 3.) ; in some, however, two and even three or four nucleoli
appear, these resulting from the division of the substance of
the single primary nucleus.

The effect of a weak solution of acetic acid is the same as
that of water, except that an additional number of corpuscles
are seen after its application to possess the divided nucleus,
whilst in others the single nucleus is observed to be oval,
and occasionally contracted in the centre, this form being
the transition one from the single to the double nucleus.
(See Plate XL fig. 4.)

If undiluted acetic acid be used, then all the corpuscles
will present a compound nucleus, consisting of two, three,

MUCUS. 127

four, or five nucleoli, the usual number being two or three ;
the investing membrane at the same time under its influence
loses its granular aspect, and appears transparent and smooth.
(See Plate XL fig. 5.)

The formation of these nucleoli may be thus explained : —
The effect of acetic acid is to contract the entire corpuscle; on
the nucleus, however, it would appear to operate with such
force as to occasion a complete division of its substance.

The divided nucleus has been observed by many observers
in the pus globule, but its occurrence in the mucous cor-
puscle has not been generally noticed ; this division of the
nucleus has been considered to constitute an exception to the
law of the development of a cell around a single nucleus ;
whether it ought to be so regarded is doubtful, seeing that
these multiplied nuclei are usually the result of the operation
of a powerful re-agent, and are but rarely visible, unless as
the consequence of the application of some re-agent.

Mr. Wharton Jones has endeavoured to meet this conceived
exception, by supposing that the nucleoli are all enclosed
within the membrane of the nucleus. I have myself, how-
ever, failed to detect the existence of any envelope surround-
ing the nucleoli.

Form. — The form of the mucous corpuscle, although usually
spherical, is subject to considerable variety, this depending
frequently upon the density of the fluid in which it is im-
mersed, but occasionally also upon the amount of pressure to
which it may be subjected.

Thus, in fluid which is very dense, the operation of exos-
tosis is set up between the corpuscle and the fluid medium
which surrounds it, whereby a portion of its contents passes
into that medium, as a consequence of which its investing
membrane collapses and exhibits a variety of forms. (See
Plate XL fig. 2.)

Corpuscles thus affected nevertheless retain the power of
re-assuming the form which properly belongs to them when
they are immersed in water or any other liquid, the density
of which is less than that of the fluid contained within the
cavity of the corpuscle itself. (See Plate XI. fig. 3.)

128 ORGANISED FLUIDS.

The form of the mucous corpuscle is also subject to alter-
ation from another cause, viz. pressure. Thus it is often seen
to be of an oval form in thick and tenacious mucus ; this
shape results from the pressure exercised upon the corpuscles
by the almost invisible fibres into which the fluid part of mucus
resolves itself, and which often become drawn out in the ad-
justment of the mucus on the port-object of the microscope.
(See Plate XII. ^.3.)

The oval shape thus impressed upon it is permanent, be-
cause the pressure of the fibres of the solid mucus ceases not
to act: if the pressure however be direct, and the corpuscle
be immersed in a thinnish fluid, it will resume the spherical
form, the compressing force being removed, owing to the
elasticity with which it is endowed.

Size. — The size of the corpuscle is also liable to much
variation, this resulting mainly from the condition of the fluid
as to density, in which it is immersed.

Thus, in water, or any other fluid, the density of which is
less considerable than that of its contents, the corpuscle im-
bibes by endosmosis the liquid by which it is surrounded, to
such an extent as to cause it to exceed by two or three times
its former dimensions. (See Plate XI. Jig. 3.)

By reference then to the two particulars referred to, viz..
the density of the medium in which it dwells, and pressure
we are enabled to explain all the varieties of form and size
which the mucous corpuscle presents.

Properties. — From the preceding remarks on the structure,
form, and size of the mucous corpuscle, we perceive that in all
these particulars, it accords closely with the white corpuscles
of the blood ; we shall now proceed to show that there are
other points of resemblance between the two organisms.

Thus re-agents affect mucous corpuscles in a manner
precisely similar to that in which they act upon the white
globules of the blood; water causes them to increase in
size, acetic acid contracts them somewhat and renders the
nucleus and the molecules more distinct. Between mucous
corpuscles and the white globules of the blood there is, then,
a structural identity ; but let us see if there be not also a
functional correspondence.

MUCUS. 129

NATURE OF MUCOUS CORPUSCLES.

Mr. Addison * conceives " that mucous and pus globules
are altered colourless blood-corpuscles/' from which opinion
it is evident that gentleman believes that the white cor-
puscles of the blood pass normally through the walls of the
blood-vessels, although he does not appear satisfactorily to
have witnessed the exact manner of their escape.

The perfect identity of organization existing between the
colourless corpuscles of the blood and mucous and pus globules,
would predispose the mind to adopt that view as sufficient
and correct, which endeavoured to prove that they all had
a common origin in the blood.

It must nevertheless be remembered that the notion of the
identity in origin of the mucous and pus globule with the
colourless blood-corpuscle, rests upon the single supposition
that the latter does really escape from the blood-vessels, in
which originally it is formed.

It seems to me, however, that this statement, to which I
was myself at one time disposed to attach some importance,
may be fairly challenged, seeing that the direct passage of
the white corpuscles of the blood appears never to have been
clearly witnessed.

Moreover, the idea of any such escape of the white cor-
puscles is opposed to that view which reasoning alone would
lead one to entertain ; thus, if the colourless corpuscles of the
blood possessed the power of escape from their vessels, no
good reason could be advanced why the red globules should
not also pass through them.

If the capillary vessels terminated by open mouths, which
we know that they do not in their normal state, then indeed
it would be highly probable that mucous and pus corpuscles
were the white corpuscles of the blood, escaped from the
vessels.

* Transactions of Prov. Mcd. and Surg. Association, vol. xii. p. 255.

130 ORGANISED FLUIDS.

I am disposed, then, to question the accuracy of the view
entertained by Mr. Addison, and to believe that the globules
of mucus are formed externally to the blood-vessels ; the
mucous glands or crypts which are scattered so abundantly
over the surface of all mucous membranes, having a consider-
able share in their formation.

That the mucus-bearing glands are intimately connected
with the development of mucous corpuscles seems proved
by the fact, that the fluid expressed from them is filled with
corpuscles of a smaller size than ordinary mucous globules,
and destitute of any admixture with epithelial scales ; these
corpuscles certainly could not have found entrance into
the cavities of the glands from without. (See Plate XI.

fig. 6.)

The opinion that the mucous corpuscles are formed ex-
ternally to the blood-vessels, is also supported by the observ-
ations of M. Vogel, who remarked that the plastic exudation
which covers the surface of a recent wound contains, at first,
only minute granules : these after a time become associated in
twos and threes, and surrounded by a delicate envelope ;
finally, fully formed mucous or pus corpuscles appear in the
liquid.

Henle believes that the white corpuscles of the blood, of
lymph and of chyle, as well as those of mucus and pus, are
elementary cells ; and he says of the pus corpuscles that they
are nothing else than elementary cells in process of being
transformed into those of the tissue which the organism rege-
nerates in the injured part ; and of the white globules of the
blood he writes, they are, without the least doubt, transformed
into blood corpuscles.

This opinion of Henle accords closely with that of Addison,
who believes, as already stated, that out of the white globules
of the blood, all other corpuscles met with in the body are
formed, the former escaping from the blood-vessels.

I also regard the white corpuscles of the blood as elemen-
tary or tissue cells, although at the same time the views
entertained by myself respecting them differ from those both
of Henle and Addison ; thus I do not consider, with the

MUCUS. 131

former, that the colourless corpuscles are transformed into
red blood discs, nor with the latter, that every other cell met
with in the animal organism, proceeds from the white cor-
puscles of the blood.

The white corpuscles of lymph, chyle, and blood I con-
ceive to be transformed into the epithelial cells, which con-
stitute the epithelium with which the internal surface of the
vessels of the entire vascular system is provided.

The corpuscles of mucus I conceive to have an origin dis-
tinct from the colourless globules of the blood ; but in like
manner I regard them as elementary or tissue cells, believing
that they are finally developed into the different forms of
epithelium encountered upon the surface of mucous mem-
branes.

The corpuscles of pus are also elementary cells, and mostly
altered mucous corpuscles.

The view just expressed as to the nature of the white cor-
puscles of the blood, is one which has but recently impressed
itself upon my mind. It is not opposed, however, to the
opinion previously put forth of the connection existing be-
tween these corpuscles and nutrition, seeing that, whether in
their early stage of development as colourless blood globules,
or in the more mature condition of their growth as epithelial
scales, they are doubtless to be regarded as secreting organs,
and as effecting some important change in the constitution of
the liquor sanguinis.

The only respect in which the opinion that the colourless
globules of the blood are converted into the scales which
constitute the lining epithelium of the vessels, is at variance
with a previously expressed view, is in relation to the escape
of those globules as an usual occurrence ; an opinion of Mr.
Addison, in which I was formerly disposed to concur, but
which I am now inclined to reject.

A final^ reason which may be stated for disbelief in the
identity as regards the origin of the colourless corpuscles of
the blood and mucous globules, is the difficulty, not to say
impossibility, of explaining how these colourless corpuscles,
having precisely the same form and origin in the commence-

M

132 ORGANISED FLUIDS.

ment, should, in one situation, be developed into a shape and
a structure so totally dissimilar to that which the same cor-
puscles in another position exhibit, the varieties of form and
structure of epithelial scales into which the white corpuscles
are supposed to be developed being so considerable.

Mucous globules, then, are to be regarded as young epi-
thelial scales, as are also the colourless globules of the blood ;
they both have a like structure and a corresponding function
to perform, but they have a different origin, thus the mucous
globules are developed externally to the lymphatics and blood
vessels, while the colourless blood corpuscles are formed within
those vessels.

The further consideration of the ulterior development of
mucous corpuscles, or young epithelial cells, will come more
appropriately under the head of Epithelium.

Blood corpuscles not unfrequently occur mixed up with
mucous globules, as in the mucus thrown off during par-
turition (see Plate XII. fig. 1.), and as in the rust-coloured
expectoration of Pneumonia.

THE MUCUS OF DIFFERENT ORGANS.

After the threefold division of mucus which we have
given, founded upon the structure of the membranes by
which it is secreted, and after the description which has been
entered upon of the peculiarities appertaining to the mucus
of each of those divisions, it will be unnecessary to enlarge
at any length upon the characters presented by the mucus
secreted by the membrane which belongs to each particular
organ or part ; it will be sufficient just to enumerate the
names of the membranes by which each description of mucus
is furnished, and to point out any peculiarities which the
mucous secretion of any particular organ may present : this
having been done, and the distinctive characters of the three
forms of mucus having been recalled to mind, we shall then
be in a position to assign to the mucus of each locality its
principal characteristics.

MUCUS. 133

Thus the mucus furnished by the nasal and bronchitic
mucous membranes, and which may be called nasal and
bronchitic mucus, as also that of the digestive tube, from the
pyloric orifice of the stomach unto near the termination of
the rectum (the caecum alone excepted), of the urethra, pro-
static gland, vesiculae seminales and the uterus, belongs to the
first division of mucus, viz. that which is secreted by the
true mucous membranes. (See Plate XII. fig. 3.)

The mucus of the vagina presents the best example of the
mucus of the second class, which is secreted by the false mu-
cous membranes. (See Plate XII. fig. 1.)

Lastly. The mucus of the mouth, rectum and bladder,
appertain to the third description of mucus, and which is
supplied by the mixed mucous membranes. (See Plate XII.

fig. 2.)

Vaginal and Uterine Leucorrhea.

One practical result arising from the discrimination of
mucus into different kinds may here be alluded to ; thus by
means of the difference in the microscopic characters of the
mucus secreted by the uterus and that furnished by the
vagina, it is in our power to decide in cases of leucorrheal
discharge, whether the affection has its seat in the mucous
membrane of the uterus or in that of the vagina. The mucous
membrane of the uterus, as we have seen, belongs to the class
of true mucous membranes, that of the vagina, on the con-
trary, to the false mucous membranes ; now if the leucorrhea
be uterine, the discharge will present the globules charac-
teristic of the secretion produced by the class of true mu-
cous membranes ; if, on the other hand, it be vaginal, the
mucus will contain the epithelial scales which belong to the
mucus of false mucous membranes ; moreover, the former
mucus will be alkaline, and the latter acid.
/

Effect of Acid Mucus on the Teeth.

The degree of acidity presented by the mucus of the mouth
varies considerably, according to the relative proportions of

M 2

134 ORGANISED FLUIDS.

mucus and saliva which exist in the mouth at the time at
which the re-action of its secretions is tested, and which pro-
portion differs both at different times of the day, and in
different states of the system, and especially of the stomach.
The mucus of the mouth we know to exhibit in states of
health an acid re-action, while the saliva, on the contrary,
manifests an alkaline constitution ; the tendency of these
two fluids is therefore to produce a neutral secretion, and this
explanation will account for the opposite results which have
been obtained by different observers. The best time to as-
certain the chemical re-action of the buccal mucus is in the
morning when there is an accumulation of it on the tongue
and around the gums ; and the best method of determining the
acid or alkaline qualities of the saliva, is first to scrape the
tongue well, and as far as possible free the mouth of mucus,
and then proceed to test the saliva as it issues from the
orifices of its ducts.

A highly acid condition of the mucus of the mouth is
assuredly productive of injurious effects upon the teeth.
Although this state of the buccal mucus cannot be regarded
as giving rise to the peculiar caries to which the teeth are so
remarkably liable ; nevertheless it cannot be doubted that it
predisposes the teeth to this affection, and that it hastens
greatly the progress of the decay when once this has com-
menced. To correct the condition of the stomach if it be
faulty, the internal administration of alkalies should be had
recourse to ; and to remedy the local acidity, tooth powders,
composed principally of some alkaline carbonate, should be
employed.

The Vaginal Tricho-Monas.

M. Donne has discovered in the vaginal mucus of women
labouring under discharges, either specific or otherwise, a
new species of human parasite belonging to the order of
Infusoria?. This animalcule, owing to its resemblance to
the spherical mucous globules with which it is constantly
associated, is with difficulty discoverable by those who are

MUCUS. 135

not practically familiar with its appearance, and the mode of
detecting it. Thus it presents nearly the same size, form,
granular structure, and colour as the mucous corpuscles
alluded to ; it is to be distingushed from these, however, by
the independent locomotive power which it possesses, the
movements which it performs being produced principally by
means of a long lash or cilium with which its anterior ex-
tremity is furnished, and the presence of which causes the
animal to lose somewhat its circular contour, and assume a
form approaching the oval ; in addition to this long cilium,
three or four other shorter cilia exist, which surround the
mouth, and which can only be satisfactorily detected when
the motions of the animalcule become somewhat retarded.
(See Plate XII. Jig. 6.) In order that it may be seen alive
and in active movement, it is necessary that the mucus con-
taining it should be submitted to examination as soon as
possible after its removal from the vagina ; the animal once
dead, it is then almost impossible to distinguish it from a
mucous corpuscle.

M. Donne, on first discovering this parasite, was for some
time in doubt as to whether its occurrence was to be re-
garded as having any connection with the specific disorders of
which the vagina is sometimes the seat, and he has at length
arrived at the conclusion that no such relation as that sus-
•pected exists, and that any inflammation, specific or otherwise,
sufficiently active to give rise to the secretion of puriform
matter, may be accompanied by the tricho-monas which has
been described.

In addition to the positive characters which have been in-
dicated, denoting the presence of this animalcule, there is
another altogether indirect which serves to signalise its ex-
istence in the vaginal mucus, and this is the presence in it
of air-bubbles which are not encountered in healthy mucus.

t

Vaginal Vibrios.

The tricho-monas is not the only animalcule which lives
in the mucus of the vagina ; there are frequently met with

M 3

136 ORGANISED FLUIDS.

in it minute vibrios^ which, to be satisfactorily seen, require
to be viewed with a magnifying power of not less than the
j~ of an inch.

In the same manner as the tricho-monas, they always
occur in connection with pus globules ; they are not, how-
ever, any more than the tricho-monas, to be regarded as
indicating the existence of specific or venereal affections,
although they are not unfrequently met with in the secretion
of chancres of an undoubtedly specific character.

PUS. 137

ABT. IV. PUS.

GENERAL CHARACTERS.

HEALTHY, phlegmonous, or laudable pus, is a fluid of the
colour and consistence of cream, readily miscible with water,
in which after a time it sinks ; it does not admit of being
drawn out into threads, and exhibits usually an alkaline,
though sometimes an acid, re-action.

Like mucus, which it resembles so closely, pus is made up
of two constituents, the one fluid, the other solid ; these, if
allowed to stand at rest for a time, will undergo a spontaneous
separation from each other, the corpuscles subsiding to the
bottom, and the fluid or serum floating upon the top; this
also will be frequently observed to be covered with a delicate
film composed of oil globules. The fluid portion of pus, as
of mucus, is probably the only essential, as it certainly is
its only distinctive constituent ; but while the latter is some-
times free from globules, the former is never without a
greater or less amount of corpuscles, on the presence and
numbers of which its opacity, its colour, and its consistence
mainly depend.

The general characters of pus, however, undergo many
changes in disease ; thus its consistence, colour, smell, and
all other sensible qualities vary greatly in pathological con-
ditions.

IDENTITY OF THE PUS AND MUCOUS CORPUSCLE.

The globules of pus resemble in all essential particulars
those of true mucus, the characters of which have been
already described; thus, they present the same form, the
same constitution, and they comport themselves in a manner
almost identical with chemical re-agents. (See Plate XL
fig. 1., and Plate XIII. fig. 1.)

In one respect only can a difference in the effect of re-
agents on the pus and mucous corpuscles be detected ; this

M 4

138 ORGANISED FLUIDS.

difference is, however, one of degree, and not of kind ; thus
the mucous corpuscle is less readily acted upon by the acids
than the pus globule ; in the former a solution of acetic acid,
not too concentrated, will often disclose but a single, although
large, nucleus ; while the same solution applied to the latter,
will render apparent seldom less than three or four nucleoli.
(See Plate XIII. fig. 2.) This is, however, by no means a
constant result, and the effect of the application of strong
acetic acid to the mucous globule is almost invariably to
render apparent three or four nucleoli ; so that from the cir-
cumstance of the number of nuclei disclosed by acetic acid,
no opinion can be formed as to the nature of the corpuscle,
whether it be a mucous or a pus corpuscle. Of the accuracy
of this view, notwithstanding that a contrary opinion is held
by many observers, not a doubt can be entertained.

It is not in every example of pus that we find the well
formed and spherical corpuscles, which characterise healthy
and normal pus. In the pus which has been long secreted,
as in that of old abscesses, we find but few corpuscles, the
majority being broken up and reduced to their elementary
particles. (See Plate XIII. fig. 5.)

The best examples of pus corpuscles are seen in pus which
has been but recently secreted, as in that just formed on some
healthy granulating surface. (See Plate XIII. fig. 1.)

When, therefore, pus and mucous globules are spoken of,
it is not to be understood that these terms indicate two dis-
tinct structures, but merely the occurrence of the same solid
element in two fluids, which, although usually presenting some
points of difference, are in all probability not essentially
distinct.

THE NATURE, ORIGIN, AND FORMATION OF PUS
CORPUSCLES.

In having indicated the nature of mucous globules, we
have also, to a very great extent, pointed out that of pus
corpuscles, seeing that the corpuscles of both have an organi-
sation precisely similar.

PUS. 139

One of the earliest opinions formed in reference to the
nature of pus was, that it was constituted of blood deprived
of its colouring matter, a view which was entertained even
before the discovery of the blood corpuscles themselves.

Subsequently to the period of the detection of the red cor-
puscles in the blood, many observers have conceived that pus
consists of these corpuscles altered merely in colour.

A third opinion in reference to the formation of pus and
mucous globules is that of Vogel, who maintained that they
arose out of a transformation of the epithelium, the nuclei of
which constituted the corpuscles. This view, although not
without ingenuity, has but little even of probability to re-
commend it, and it will be perceived that it is the very
reverse opinion to that which is maintained in these pages,
and which is that the epithelium is itself derived from
mucous and pus globules.

We have already, under the head of Mucus, adverted to
the opinion of Addison, that mucous and pus globules are
altered colourless blood corpuscles, an opinion which we
have also endeavoured to refute, principally by reference to
the impossibility, save from lesion, of the escape of the white
corpuscles from their containing vessels.

Reference has also been made to the view entertained by
Henle respecting the nature of pus corpuscles, who says of
them that they are nothing else than elementary cells in pro-
cess of being transformed into those of the tissue, which the
organism regenerates in the injured part.

I also agree with Henle in considering pus corpuscles to
be elementary cells, but I differ from him in not regarding
them as representing the cells of the tissue in which the pus
is formed.

Pus corpuscles I conceive to be identical with mucous cor-
puscles, and these again are to be regarded as representing an
early stage in the development of epithelial scales.

FurtKer, it is here supposed that the formation of pus is
to be viewed in the light of a salutary process, and as indi-
cating the effort on the part of the organism, where sup-
puration occurs as the result of lesion of any kind, to repair

140 ORGANISED FLUIDS.

the mischief sustained, and which it does by the elaboration
of pus corpuscles capable of being transformed into a pro-
tecting epithelium.

In support of this view reference may be made to the fact
that it is by no means uncommon to encounter epithelial
scales mixed up with the ordinary pus corpuscles contained
within the cavity of an abscess, or covering the surface of an
old ulcer.

But it may be asked how happens it then that all pus cor-
puscles do not become converted into epithelial scales, and
that so many of them are discharged or thrown off from the
system without attaining to the higher degree of development
of which they are stated to be susceptible.

This arrest of development doubtless arises from the ra-
pidity with which the pus corpuscles are formed, and which is
indicative of the strength of the Vis medicatrix natures, the
result of which is that the earlier formed corpuscles become
displaced by the more recently developed ones, and are thus
removed without the sphere of growth, in consequence of
which they perish.

Having thus considered the nature of pus corpuscles, we
will next endeavour to form some opinion in reference to
their origin and mode of formation ; in these respects also an
essential correspondence doubtless exists between pus and
mucous globules.

Mandl attributes to the pus globule the same mode of
formation which he has described as belonging to the white
corpuscles of the blood, that is, that they are formed external
to the vessels by the aggregation of molecules precipitated
from the fibrin, and hence Mandl terms both the white and
pus corpuscles " fibrinous globules."

This view of the formation of pus corpuscles is supported
also by the observations of Vogel (already cited) made upon
abraded surfaces.

Mandl, therefore, is most probably correct in his opinion
as to the mode of formation of pus corpuscles, viz. by pre-
cipitation, but it is at the same time almost certain that they
are not constituted of fibrin, as supposed by that micogra-

PUS. 141

pher: this may be inferred from the different manner in
which acetic acid acts upon fibrin and pus corpuscles ; thus
the former swells up and is rendered soft and friable by its
application, while the latter under its influence become
smaller, and their contained molecules more distinct.

Donne dissents from Mandl's view altogether. At page
191. of the Cours de Microscopic, M. Donne expresses him-
self as follows : — " Thus I do not admit that the globules
of pus are formed at the expense of the fibrin of the blood ;
that they ought to be considered as a sort of precipitate
of the fibrinous part of the fluid blood ; and in spite of
their analogy of structure and composition with the white
globules of the blood, I nevertheless do not admit that they
have any thing in common in their origin and in their in-
timate nature with these last. I regard the globules of pus
as a product of special secretion direct from the pus forming
membrane."

There appears to me to be much of error in the preceding
observations : there is doubtless very much in common be-
tween the white corpuscles of the blood and pus globules,
viz. a common mode of formation and a common function to
perform.

At the same time it must be admitted, with Donne, that
the surface or membrane, from which the pus proceeds, is
also intimately associated with the development of the pus
corpuscles.

DISTINCTIVE CHARACTERS OF MUCUS AND PUS.

We have now to ask ourselves the question, which doubt-
less many have applied to themselves before, viz. what are
the distinctive characters between mucus and pus revealed to
us by the microscope, and the satisfactory recognition of
which has been deemed to be of so much importance ?

To this inquiry no sufficient answer has as yet been re-
turned : this difficulty the microscope has failed to solve ; and
this, in all probability, for the very adequate reason, that

142 ORGANISED FLUIDS.

between the fluids in which a distinction has been sought
no microscopic difference exists. The inquiry has been made
on the false assumption that mucus and pus are really essen-
tially distinct ; and its importance has been magnified by the
idea that it would impart, as indeed it undoubtedly would do
if real, increased assistance in the diagnosis of disease.

Since, however, the establishment of the fact that pus may
be formed independently of any appreciable structural lesion,
much of the interest which was supposed to attach to this
inquiry has been lost, and that which still appertains to it
has been further lessened by the demonstration at which
we have arrived, by means of the microscope, of the perfect
identity of pus and mucous corpuscles.

Now the manifestation of this identity by the microscope
is not less a triumph of that instrument than if it had really
proved that the notion of physiologists was actually founded
on fact, and that there does really exist a tangible difference
in the microscopic characters of the two fluids.

Notwithstanding the absence of any positive known mi-
croscopic character, whereby at all times, and in all conditions,
pus may be discriminated from mucus, this want of know-
ledge, arising from the very sufficient fact to which allusion
has already been made, viz. that no such character really
exists, the two fluids under discussion may frequently be
distinguished, at a glance, by certain outward and physical
properties and appearances, and this is especially the case
when they occur without admixture with each other.

These differences in the outward character of the two
fluids are not always, however, equal to their discrimination,
and which arises from the fact, that they are all of them
subject to the greatest possible variation, so that there is not
one which can be regarded as truly distinctive. Thus in
morbid conditions, the one fluid will pass by insensible
degrees into the other, or they will both be mingled together
in such proportions as to set at defiance all physical means
employed to distinguish them.

But it may be said that the chymist can at all times dis-
tinguish pus from mucus : there can be no doubt but that,

PUS. 143

when all other means have failed, he can occasionally arrive
at a tolerably accurate conclusion, but it is conceived that his
powers in this respect are also limited.

Now the physical and chemical difficulties encountered in
the endeavour to discriminate pus from mucus arise, in all
probability, from the same cause which rendered it micros-
copically impossible so to do, viz. that no constant or essen-
tial difference does really belong to these fluids, whereby at
all times they may be characterised.

Normal mucus and pus may be contrasted as follows : —
Mucus is a thick, tenacious, and transparent substance,
easily admitting of being drawn out into threads, not readily
miscible with water, in which it floats, not so much from its
less specific gravity as from the circumstance of its great
tenacity, allowing it to retain in its substance numerous air
globules, which thus render it specifically lighter than the
water : it exhibits sometimes an acid, and sometimes an alka-
line reaction, according to the nature of the surface from
which it proceeds ; and it contains imbedded in its substance
solid particles of two forms, globules and scales : the former
are present in alkaline mucus, the latter in that which mani-
fests an acid reaction.

Pus, on the contrary, is a thick, opaque, somewhat oily
substance, which does not admit of being drawn out into
threads, is readily miscible with water, in which it sinks ; its
chemical reaction varies, being sometimes alkaline, at others
acid : the solid particles which it contains are mostly of one
kind, globules : these are always very abundant, and float
freely in the fluid portion of the pus, while in that of mucus
they are unable to do so on account of its tenacity.

Healthy mucus and pus, when thus contrasted, may fre-
quently be distinguished from each other, but it is in un-
healthy conditions of these two fluids, and especially when
they occur mixed together in variable proportions, that the
difficulty of discrimination is felt, and that the want of a
certain and positive character, whereby the diagnosis may be
always established, is experienced.

This mixture of mucus and pus may actually exist, or

144 ORGANISED FLUIDS.

it may not, in cases of suspected phthisis, in which sputa are
present. Now it is in cases of this description that we recog-
nise the importance of the discrimination of these substances,
and it is precisely in these and similar instances that the
microscope utterly fails us, for the want of an ascertained and
tangible difference in the two fluids submitted to the test of
its powers.

Even the most marked physical qualities of pus, such as
its opacity and tenuity, may all be effaced by the employ-
ment of certain reagents, and converted into those which are
characteristic of mucus, thus pus, by the addition to it of
liquor potasses or of ammonia) is rendered transparent, and is
transformed into a thick and tenacious substance, resembling
mucus closely. This singular fact has been noticed by both
Addison and Donne, and on it the former clever observer has
built a theory remarkable for its ingenuity, but which is
here, nevertheless, deemed to be incorrect.

The change of pus from an opaque substance to a trans-
parent one doubtless results from the solution of the pus
corpuscles, and to the presence of which the colour and
opacity of pus is due ; of the increased density and tenacity
of the pus thus treated it is less easy to afford a satisfactory
explanation.

Addison thus accounts for it : the mucus and pus globules,
he says, contain filaments embedded in a fluid; these the
liquor potasses sets free by dissolving the envelopes of the cor-
puscles, and it is upon these filaments that the tenacity of
mucus, and of pus so acted upon, depends. Mr. Addison,
however, carries his reasoning upon the fact of the conversion
of pus into a fibrillating substance similar to mucus still
further. The white corpuscles of the blood, he states, also
contain fibres, and that these corpuscles, immediately on
their abstraction from the system, burst, giving issue to the
contained filaments.

These filaments, he conceives, to constitute the fibrin of the
blood, which he declares does not exist in that fluid as fibrin,
but is only liberated from the corpuscles after the abstraction
of the blood from the system.

PUS. 145

The entire of this theory is here conceived to be erroneous,
and this for the following reasons : —

1. The existence of such filaments in the white corpuscles
has not been proved.

2. The bursting of these corpuscles referred to by Mr.
Addison, is an occurrence which is rarely, if ever, seen to
take place while they remain embedded in the liquor san-
guinis.

3. The actual consolidation of the fluid fibrin may be wit-
nessed to occur on the field by the microscope in a drop of
blood, and wholly independent of any rupture of the white
corpuscles, which remain without appreciable alteration.

There is some consolation, however, in knowing that this
inquiry is not of so much importance as it would appear ; for
even were we able to make the distinction which has been
the subject of so many anxious thoughts, and decide that pus
did exist in the sputa, yet this fact, viewed separately, would
not prove that disease of the lungs did really exist, since it
is ascertained that pus may be formed without any structural
lesion ; and, further, if lesion were really present, it would
not necessarily follow that this had its seat in the cells of the
lungs, for it might be situated either in the bronchi or larynx.
Thus even in this supposed case the diagnosis would be sub-
ject to considerable uncertainty.

Various opinions have been expressed by different ob-
servers in favour of the possibility of distinguishing pus from
mucus. To some of these we will now refer.

There is always met with in pus, in greater or less quan-
tity, globules of oil : the presence of these was conceived by
Gueterboch to afford a sign, absolutely distinctive, between
pus and mucus ; that they are not so, however, is proved by
the fact that similar globules are occasionally encountered in
normal mucus.

Weber conceived the idea that the fluids might be dis-
tinguished by the size of the globules contained in them, the
pus globule being twice as large as that of mucus : this cha-
racter is likewise too uncertain, and too* variable for the
purposes of discrimination.

146 ORGANISED FLUIDS.

Lastly, Gruithuisen indicated, in solutions of pus and
mucus in water, certain animalculae ; those generated in
the former being different from those formed in the latter
solution. By means of these he asserted that pus might always
be known from mucus ; but the infusoria described by him
are not confined to the fluids in question, but are such as are
formed almost indifferently in any solution of animal matter.
It would appear, then, that up to the present time no satis-
factory and direct means of distinguishing pus from mucus
have been detected, and this for the reason assigned, that the
two fluids are essentially identical.

DISTINCTIONS BETWEEN CERTAIN FORMS OF MUCUS
AND PUS.

Although it is impossible to discriminate between true
mucus and pus by means of the microscope in a positive
manner, we are yet enabled to distinguish with that instru-
ment false mucus from pus, because in this mucus the cor-
puscles exist in their fully developed form of tessilate epithe-
lium ; now this power of discrimination is not without im-
portance, as will be perceived immediately.

Many persons on arising in the morning are in the habit
of expectorating more or less of a substance bearing much
resemblance to pus. This habitual occurrence is not un-
frequently a source of much uneasiness, not merely to the
person the subject of it, but also to his medical adviser whom
he is led to consult upon it.

Now, in such cases as these it is often in our power to
dispel the anxiety of our patient and our own at the same
time ; for the solid constituents of such sputa are frequently
found to consist almost entirely of epithelial cells, in which
case we may safely pronounce that they are not purulent ;
if, on the contrary, the sputa contain only globules, the evi-
dence which this fact would furnish, although apparently,
and indeed most probably, unfavourable, would still be but of
a doubtful nature.

PUS. 147

Again, the microscope will frequently determine the nature
of a suspected fluid, by indicating in it the existence of
shreds of cellular tissue, muscular fibrillse, and a variety of
other organisms which enter into the formation of the human
body ; and by the presence of one or more of which, not merely
the nature of the puriform matter may be ascertained, but
also the locality from which the pus had itself proceeded.

DETECTION OF PUS IN THE BLOOD.

From what has been said in reference to the structural
identity of the white corpuscle of the blood with that of
mucus and pus, we are prepared for the announcement that
no known characters exist whereby the presence of pus in the
blood may be established by the microscopic examination of
that fluid.

That the elements of pus in some cases are really present
in the blood, circulating with it, scarcely admits of a single
doubt, since it is not unfrequently met with in situations, such
as on the lining membranes of the vessels, where it is utterly
impossible for it to remain without some portion of it be-
coming commingled with the blood.

The same fact is also proved by the spontaneous absorp-
tion of large collections of matter, an occurrence which is not
unfrequently witnessed, and which is only to be accounted for
on the assumption that the elements of pus are again absorbed
into the blood from which originally they were derived.

There can scarcely be a question, then, that pus is occa-
sionally contained in the living blood, although we possess
only indirect means of establishing this fact ; and according
to the views here entertained, it may be present in the blood
in two ways : thus, as we have seen, it may be formed in the
blood-vessels themselves, or it may be formed without those
vessels, and again reabsorbed into the blood from which in
every case it almost immediately proceeds.

But pus, as we know, is composed of two elements, the one
fluid, the other solid, the globules. Now we must not expect
t<> >rc pus circulating in the blood as pus, although that

N

148 OEGANISED FLUIDS.

liquid may contain all the elements of pus : the fluid portion
of course, as soon as it enters the circulation, is dissipated,
the solid alone remaining, and this does not constitute pus,
but is only one element in the constitution of that fluid.

In certain states of disease the presence in the vessels of an
unusual number of white corpuscles has been observed ; now
it is but little probable, that these are derived from the re-
absorption of pus, which had been previously formed with-
out those vessels; it is more natural, and more consonant
with known facts, to suppose, that this accumulation is to
be regarded as an indication that the disposition to the
formation of pus, on the part of the blood and of the system,
exists to an unusual extent, and that such a condition of the
vital fluid always precedes sudden and extensive purulent
collections.

Except in the case of the formation of pus in the blood-
vessels themselves, it is scarcely possible to suppose that
the pus corpuscles are taken bodily into the circulation
again; but it would rather appear, from the condition of
pus in most abscesses, that the corpuscles become disinte-
grated and reduced to their elementary particles, and that
thus they enter the circulation again in a fluid state.

The artificial admixture of pus with the blood imme-
diately after its escape from a vein, and before its coagula-
tion has commenced, is productive of somewhat singular
results. The clot formed in blood, which has been mixed
with one quarter part of its own quantity of pus, is soft,
diffluent, and dark coloured, sometimes almost livid, and
the red corpuscles are found to be wrinkled and deformed,
part of their colouring matter having escaped from them
and passed into the serum.

These changes ensue in from twenty-four to forty-eight
hours, and possibly result from the state of decomposition in
which the pus itself might have been when introduced into
the blood, and which condition it communicated to the mass
of the blood itself.

rus. 149

FALSE PUS.

There are many substances and fluids having resemblance
to pus which are not really purulent ; thus, softened clots of
fibrin, which are so frequently encountered, especially in
phlebitis, bear the closest possible similitude to true pus in
general appearance, and yet in their intimate structure they
are totally dissimilar, as may be clearly determined by means
of the microscope.

If a portion of softened fibrin be examined microscopically,
it will be found to be made up of a granular material, from
which pus corpuscles, or corpuscles similar to them, are either
entirely absent, or in which they occur but in very small
numbers : now, with true pus, the reverse is the case ; the
corpuscles are its chief and most conspicuous element.

It is only by means of the microscope that the nature of
softened fibrin can be ascertained ; until within the last few
years it has always been mistaken for true pus, and the oc-
currence of masses of fibrin thus altered in the blood-vessels
has led to the opinion that the formation of pus in them is
not an unfrequent event.

On the other hand, fluids are sometimes met with which
look very unlike proper pus, and which are yet found on ex-
amination to be veritable pus. These facts show the neces-
sity of a careful microscopic examination in all important and
doubtful cases.

METASTATIC ABSCESSES.

Another notion, the erroneousness of which has been ren-
dered manifest by means of the microscope, is that which has
been entertained in reference to the removal of an abscess
seated in one part of the body, and its subsequent deposition
in another situation.

The knowledge of the existence of pus "corpuscles in the
fluid of abscesses, and the fact that no channels exist by which

N 2

150 ORGANISED FLUIDS.

they can be conveyed bodily from one part of the system to
another, clearly show that any such translation of the matter
of an abscess as that presumed is an occurrence beyond the
range of possibility.

Abscesses may indeed be re-absorbed into the system, as
daily observation teaches us to be the case, and other purulent
depositions take place subsequently to the resorption of the
matter of the first abscess ; but the elements of pus, and as-
suredly its solid constituents, are not carried into the con-
stitution bodily and without alteration"; the corpuscles doubt-
less become disaggregated, and in all probability reduced to
a fluid state previous to absorption, so that it cannot be the
same purulent matter which constitutes the pus of the sup-
posed metastatic abscess.

The simultaneous or consecutive occurrence of abscesses
in different parts of the body, may be satisfactorily explained
by reference to the condition of the system, or perhaps more
immediately of the blood itself, which is evidently charged
with purulent matter, and of which it relieves itself by the
formation of abscesses.

VENEREAL VIBRIOS.

M. Donne has discovered in the pus of syphilitic primitive
ulcerations, and of chancres which have not been treated with
topical applications, numerous vibrios of excessive tenuity.
(See Plate XIII. fig. 6.)

These vibrios are not encountered in the pus of secondary
chancres, nor even in that of buboes, which, according to the
experiments of M. Kicord, is capable of giving origin to a
chancre by inoculation.

Neither are they to be met with in the pus proceeding
from wounds, nor in foetid pus altered by the contact of the
air.

Again, in the instances in which suppuration has been
artificially excited around the edge of the glans penis, the
ordinary situation of primary syphilitic ulcerations, the vibrios

PUS. 151

are invariably found to be wanting in the discharge thus
created. This experiment proves that locality has nothing
to do with the development of the vibrios.

Finally, if inoculation be practised with the pus of a
chancre containing the vibrios, the matter of the pustule re-
sulting from the inoculation will also be found to contain the
animalcules.

Now, the inference to be deduced from these several facts
and experiments is, that if the vibrios in question be not
intimately connected with the propagation of the syphilitic
virus, that the matter of syphilis is at least peculiarly fitted
for their development.

It is probable that the presence of these vibrios accounts,
in a great measure, for the beneficial effects of topical appli-
cations, which act by killing the animalcules.

MILK. 153

ART.V. MILK.

THE general aspect and qualities of milk are known to all ;
they need not therefore be here detailed.

Healthy and fresh milk, when submitted to the action of
test paper, exhibits an alkaline reaction : in states of disease,
however, and some time after its removal from the mam-
mary gland, it frequently manifests more or less of an acid
reaction.

Like the other fluids which have as yet been described in
this work, milk is made up of two distinct elements, the one
fluid, the serum, — the other solid, the globules; these, a few
hours after its abstraction from the system, and when left
at rest, undergo to a certain extent a spontaneous separation
from each other, the larger globules ascending to the surface
forming a scum or cream, while the smaller remain diffused
through the subjacent serum.

The following analyses will serve to give an idea of the
composition of milk.

The relative proportions of the organic constituents of
human milk are thus estimated by Simon :

88-06 water.
3*70 caseine.
4-54 sugar.
3-40 butter.
0*30 salts, extractives, &c.

The inorganic components of the milk of the cow are com-
puted as follows by Haidlen :

Chloride of sodium - 0-024.

Chloride of potassium - 0-144.

Soda - 0- 42.

Phosphate of lime - - 0-231.

Phosphate of magnesia -„ 0-042.
Phosphate of the peroxide of iron - 0-007.
o

154 ORGANISED FLUIDS.

From the above brief sketch of the constitution of the
milk, it will be seen that a very close analogy exists between
that fluid and the blood : like it, the milk is made up of two
parts, the one solid, the other liquid ; like it too, it con-
tains all the elements requisite for nourishment and deve-
lopment, it serving for both during a very long period of the
life of the human species.

THE SERUM OF THE MILK.

The separation of the serum and the globules, accom-
plished in an imperfect manner naturally, is more completely
effected artificially by filtration, the serum, by means of the
ordinary filtering paper, may be obtained transparent and
colourless, almost free from globules, these being for the
most part retained upon the filter.

It may however be observed, that the first portions of
serum which pass through the paper will be more or less
coloured in consequence of their containing a certain number
of the smaller globules which had escaped through the in-
terstices of the paper ; these coloured and semi-opaque por-
tions of serum should be rejected.

The serum contains dissolved in it the sugar, and the
principal portion of the cheese of milk, as well as certain
salts, the principal of which are pointed out in the analysis
of Haidlen.

The cheese or caseine is an animal principle, which in its
properties approaches closely fibrin : it is precipitated by the
mineral, the acetic, and the lactic acids.

Although the greater portion of the caseine exists in the
milk in a fluid condition, M. Quevenne appears to have
established the fact, that it is also present in a solid state in
the form of globules, these being exceedingly small and re-
fracting but slightly the light ; the same globules may also
be detected in recently precipitated cheese. (See Plate XV.

fig. 5.)

M. Donne has shown that these cheese globules may be
demonstrated by the process of filtration ; thus, the first few

MILK. 155

drops of the milk of the cow, the ass, or the goat, which pass
through the filter, and which are generally white and opaque,
being rejected, and the second portion of filtered milk being
preserved and allowed to remain undisturbed for a few
minutes, it will be seen to separate into two parts, the in-
ferior of which is clear and transparent, while the superior is
somewhat opaque ; now if a drop of the fluid of this inferior
layer be examined with the microscope, it will be found to
contain an innumerable quantity of globules of exceeding
minuteness and refracting the light but feebly, as well as
occasionally other globules more rare, larger, and refracting
the light very strongly ; the former are the cheese globules,
and the latter the proper milk globules.

THE GLOBULES.

It is to the presence of the globules which occur in such
vast quantities in each drop of healthy milk that the colour
and opacity of that fluid is due.*

These globules are of perfect rotundity, their surface being
smooth, presenting a pearly aspect, and refracting the light
strongly ; the circumference of each globule is dark and the
centre light : the globules vary greatly in size ; the smallest,
which are in active molecular movement, being reduced to
mere points and not exceeding the y^uo^ °^ an mch, the
largest frequently attaining the sVoo °f an inch, and the
medium size ranging between the ^Vo" °^ an ^ncn m ^ia-
meter and the ^l^. (See Plate XIV. fig. 1.) In milk
which is healthy the globules float freely in the serum, and
do not adhere to each other.

Such is the form, appearance, and variety of size exhibited
by the milk globule ; much difference of opinion has existed

* Leeuwenhoek first clearly indicated the existence of these globules
in the milk in the following terms : " Vidi multos globulos, similes sextae
parti globuli sanguine! ; et etiam alios, quorum bini terni aut quaterni se
invicem modo attingebant, fundum versus descendere ; et multos varise
magnitudinis globulos in superficie fluitantes, inter quos posteriores adipem
sive butyrum esse judicabam."

o 2

156 OKGANISED FLUIDS.

in reference to its organisation, some observers conceding to
it a very complex structure, others denying it even the most
simple organisation.

Some of the more remarkable of the opinions entertained
by the more noted investigators may here be referred to.

According to Turpin, " the structure of the milk globule
consists of two spherical vesicles fitting the one into the
other, and enclosing in their interior very fine globules and
buttery oil." *

Mandl says, " the globules of milk ought then to be con-
sidered as organised corpuscles, composed of a membrane
probably formed of cheese, and of contents which constitute
the butter." f

Henle writes, the globules of milk " are not simple mole-
cules of grease, and have an independent membrane sur-
rounding them } ; " this he elsewhere states to be probably
composed of caseine, in which respect there is an agreement
of opinion between Henle and Mandl.

The complex structure ascribed to the milk globule by
Turpin it is altogether impossible to demonstrate; and the ex-
periments and observations which have hitherto been made
in reference to its constitution are entirely opposed to his
view, which may safely, therefore, be considered to be in-
correct.

Mandl founded his belief of the existence of a distinct
membrane enveloping the globules mainly on the following ob-
servation : — He remarked that if a little drop of milk be com-
pressed strongly between two plates of glass, the upper plate
at the same time being drawn over the surface of the other
in a straight line, the milk globules will be broken up by the
compression, and drawn out into a certain form : if a magnify-
ing glass be applied to the globules thus compressed, they
will be seen to present the appearance of long pale and
straight lines, with smaller straight lines placed usually at
right angles to the larger ones. " These little lines," he says,

* Annales des Sciences Naturelles. f Anat. Micros, p. 53.

J Anat. Gen. t. vii. p. 522.

MILK. 157

" are nothing else than the curled membranes of the globules,
the contents of which, the butter, constituting the long
streaks : we may easily convince ourselves of this by adding
a little water. The streaks disappear, and we see in their
place oleaginous drops of different forms, while the little
membranes remain either attached to the glass or indiffer-
ently curved, swimming in the serum. These membranes
are insoluble in ether, which dissolves the drops."

These observations of Mandl, presuming for a moment
that they are accurate in every particular, are yet insufficient
to prove the existence of a distinct membrane surrounding
the globules, although they certainly would be so, if correct,
to establish the fact that they are constituted of two different
substances, the one of which is soluble in ether and the other
insoluble. Had iodine been employed, and had it been im-
bibed by the supposed membrane, and turned of a deep brown,
the reality of the existence of the membrane in question
might have been considered as demonstrated : but we know
that iodine does not affect the colour of the milk globule in
the least.

I am far, however, from attaching the smallest importance
to the experiment of Mandl, because I conceive that he has
misinterpreted the appearances which he noticed. The
larger streaks are not constituted of a single elongated glo-
bule, but are made up by the union of several milk globules,
as is evident, first, from the size of the streaks, and, second,
from the traces which they bear of such a composition in
themselves ; as, for example, the occurrence of contractions at
certain intervals, while the smaller lines, and which are most
generally absent, are formed usually by other globules of
less size joining at an angle the larger streaks. The so-
lubility of the one in ether and the insolubility of the other
in that re-agent, I have not been able to observe.

The opinion of Henle that the milk globule is furnished
with an envelope rests chiefly upon the manner in which
acetic acid acts upon it.

Henle thus describes the effects of the application of acetic
acid : —

o 3

158 ORGANISED FLUIDS.

" Treated by dilute acetic acid, the globules of milk un-
dergo, little by little, a remarkable change, some of them
become oval or take the form of a biscuit; upon others,
appear gradually on one or many points a smaller globule,
which rests upon the margin and increases in an insensible
manner." * * * " If more acetic acid be added, the milk
globules appear, as it were, melted down with smooth but
irregular borders : they approach the one to the other, and
unite into large masses, which resemble perfectly melted fat
which has run along in an irregular manner. When to a
drop of milk are added two drops of concentrated acetic acid,
and the mixture then placed under the microscope, we no
longer perceive any regular globule of milk, or, at least, we
discover but very few — the most are reduced into one or
several irregular particles, which, with the naked eye, may
be distinguished upon the surface of the drop which other-
wise has become clear. The same changes are produced in
the space of a few days, when the milk, abandoned to itself,
becomes acid by the metamorphosis of its sugar." *

These ingenious observations of Henle, like those of
Mandl, are yet insufficient to demonstrate the existence of a
distinct and organised membrane surrounding the milk glo-
bule, although they would be assuredly so, if correct, to
render it quite certain that it is enveloped with a coating of
a material very distinct from fat, and probably of the nature
suggested by Mandl and Henle.

Here, again, however, it becomes a question whether the
appearances noticed by Henle have not been misinterpreted,
and whether the internal buttery substance does really pro-
trude through apertures in the envelope of the globule occa-
sioned by the action of acetic acid : in the first place, it
seems to me that the milk globules are too small to allow of
the determination of the point in question with any degree
of certainty ; and, secondly, that in those instances in which
observers might fancy that an escape of the included sub-
stance of the globule through its envelope had really oc-

* Henle, Anat, Gen. p. 521, 522.

MILK. 159

curred, such an appearance is, in all probability, due to the
adhesion together and partial fusion of two or more globules.
(See Plate XV. ^.4.)

There are other observers again, as Wagner, Nasse, and
Quevenne, who would deny to the milk globule all organ-
isation, and who regard it as of a perfectly homogeneous
nature.

The truth in this instance, as in so many others, would
appear to lie in the mean. That the milk globule is not pro-
vided with a distinct and separate membrane, similar to that
of the mucous corpuscle, is proved by the impossibility of
demonstrating the existence of any such structure, as well as
by the absence of a double line around its margin, the non-
effect of iodine, and the coalition of the globules resulting
from pressure, first observed by Dujardin.

That it is not constituted of a single perfectly homogeneous
substance is also demonstrated by the observations of Mandl
and Henle, and especially by those of the latter observer on
the effects produced by acetic acid.

That the milk globule is not wholly composed of fatty
matter is shown by its insolubility in boiling water raised to
a very high temperature, in boiling alcohol, in the alkalies,
and by the effects of the application of acetic acid. Ether
dissolves the milk globules : their solution, however, it does
not entirely accomplish on its first application, although the
ether, the moment it comes in contact with the globules,
causes them to lose their rotundity, to fall down, and to run
together into masses of various sizes, but most of which still
present a circular outline.

If a drop of milk be examined microscopically, after its
treatment by ether, a hasty observer might conclude, from
noticing so many of the circular masses alluded to, that the
re-agent had not exerted any influence on the milk globules,
and that these masses were the unaltered globules. This
view, however, a little reflection would soon show to be in-
correct ; for many of the circular bodies now noticed on the
field of the microscope are larger than even the largest milk

o 4

160 ORGANISED FLUIDS.

globules, and all of them are flat and semi-fluid. (See Plate
XV. fig. 3.)

The several facts now adduced, while they prove that the
milk globule is not organised in accordance with the inter-
pretation of the word organisation usually given, yet seem
sufficient to establish the fact that it is composed of two
distinct organic products, the one internal and fatty, and the
other external and possessed of properties distinct from fat.

This explanation of the constitution of the milk globule
serves to explain also satisfactorily the facts above alluded to,
viz. the non-action of boiling water, alcohol, and alkalies, all
of which affect more or less fat, as also the slower operation
of the ether : it also shows why boiling alcohol should imme-
diately dissolve the milk globules, to which a little acetic
acid had been previously added, this latter re-agent first re-
moving their outer coating, which is insoluble in alcohol.

Between the globules of the previously described fluids,
those of the lymph and chyle, of the blood, mucus and
pus, and the globules of milk, no structural or functional
relation whatever exists, the former being complex and
definite organisations or cells, and the latter constituted of
two distinct substances indeed, yet want entirely the attri-
butes of cells, being destitute of nucleus and cell wall.

It is of the globules just described that the cream is con-
stituted, their accumulation on the surface of the milk being
due to their lighter specific gravity ; it is also by their incor-
poration with each other, and which is effected by the opera-
tion of churning, that butter is formed.

COLOSTRUM.

The milk which is secreted the first few days after childbirth
has been denominated colostrum : it differs very considerably
from ordinary milk, being of a yellow colour, of a viscous
consistence, and containing a very large proportion of milk
globules, which give rise to the formation upon it of a thick
layer of cream ; when treated with ammonia it becomes glairy
and tenacious.

• MILK. 161

Corresponding with the outward characters of the colos-
trum, there are others indicated by the microscope not less
remarkable : thus the larger true milk globules which occur
in it are but ill defined, being irregular in form and size,
appearing as though they were but imperfectly elaborated,
and presenting rather the aspect of oil globules, while the
smaller ones are like a fine powder strewn through the serum,
and adhering to the surface of the larger globules, which also,
in place of floating freely and separately in the serum, are
agglomerated together as if held in union by some viscous
material. (See Plate XlV.jfys. 4 and 5.)

But besides the state of the ordinary milk globules just
described, there are found in the colostrum peculiar cor-
puscles of a totally distinct structure : these were first dis-
covered and described by M. Donne, who has denominated
them " Corps granuleux"

These corpuscles are mostly several times larger than the
milk globules, are less regular in form, although usually
more or less spherical in outline, and present a uniformly
molecular aspect and a yellow coloration ; the edges of the
corpuscles sometimes appear smooth as if possessed of an
envelope, at others, their margins are rough, and convey
the impression that they are destitute of any external cover-
ing. (See Plate XIV. figs. 3 and 4.) Occasionally one or
more milk or oil globules are imprisoned in the substance
of the Vorpuscles, which then occupy the position, although
they do not discharge the office, of a nucleus.

Some difference of opinion is entertained respecting their
intimate structure : Gueterbock, and probably Donne *, con-
ceive that they are furnished with an investing membrane,
and therefore that they are veritable cells, while Henle f
regards them as masses or aggregations of granules agglo-
merated together in an amorphous and mucoid substance ; an
opinion in which I concur.

Donne states that the colostrum corpuscles are soluble in
ether, and therefore that they are of a fatty nature : the

* Cours de Microscopic, p. 401. f Anat. Gen. t. vii. p. 525.

162 ORGANISED FLUIDS.

fact of their solubility, however, seems to me to be difficult
to verify ; and from observations which I have made, I can-
not help thinking that this point is scarcely as yet esta-
blished. Certain it is that corpuscles larger than mucous
globules, and in every way similar to the colostrum cor-
puscles, save that traces of nuclei may be detected in them,
appear in colostrum treated with ether.

The " Corps granuleux " are insoluble in the alkalies *,
are coloured brown by iodine, and the substance which unites
these granules is dissolved by acetic acid, f

The state of the milk just described does not continue
without alteration, each condition which has been alluded to
undergoing a daily modification : thus the milk globules from
day to day acquire greater uniformity of size and shape, they
no longer adhere together, but float freely and singly in the
serum, which does not become viscid on the addition of am-
monia, the smaller dust-like globules also altogether disap-
pearing; at the same time the number of the colostrum
corpuscles diminishes until at length none exist. (See
Plate XIV. fig. 1.)

These several changes are all accomplished in the course of
a few days, so that by the end of the twenty-fourth day, the
milk has usually entirely passed from the condition of colos-
trum, and presents only its ordinary characters. The colostrum,
however, does not always pass through its various modifi-
cations in the time specified, it may do so in either a shorter
or a longer period than that stated : thus the existence of the
milk in the form of colostrum can scarcely be regarded as
affording any very certain test whereby the age of the milk
may be determined.

The colostrum corpuscles would appear to be almost pecu-
liar to the human subject, for while their presence in the
milk of woman is almost constant, their occurrence in that of
animals, as the cow, the ass, and the goat, is rare and excep-
tional.

Professor Nasse states that they disappear sooner in women

* Donne, loc. cit. p. 401. f Henle, loc. cit. t. vii. p. 525.

MILK. 163

who have borne many children than in those who have had
but a single child.

Mucous corpuscles are also occasionally encountered in the
colostrum. They are, however, neither very generally pre-
sent, nor do they occur in any very great numbers.

The colostrum, or first milk, is possessed of purgative
qualities.

PATHOLOGICAL ALTERATIONS OF THE MILK.
Persistence of this Fluid in the condition of Colostrum.

It has been stated, that usually by the end of the twenty-
fourth day after childbirth, and frequently at a much earlier
period, the colostrum has lost all its distinctive characters,
and the milk has arrived at its perfect condition.

This transformation of the colostrum into fully elaborated
milk, it has been observed, is not always effected in the time
named : it may be accomplished in either a shorter or a longer
period ; thus the milk in some cases loses the chief characters
of colostrum in as short a space of time as three or four days,
while in others it retains them for months after the birth of
the child, and even until the end of lactation.

This persistence of the milk in the state of colostrum may
be present without any suspicion of its existence being enter-
tained, the milk exhibiting its ordinary outward appearances.

It is therefore, only by means of the microscope, that its
true condition can be ascertained. Examined with this instru-
ment, the characteristics of colostrum will be detected ; thus
the globules which do not float freely in the serum, and which
are large and ill-formed, will be seen to adhere together in
groups, as though held in union by some viscous substance,
and intermixed with them will be noticed numerous colostrum
corpuscles.

It cannot be doubted but that such persistence of the milk
in the form of colostrum exerts a most injurious effect upon
the child : the colostrum is, as we know, possessed of pur-

164 ORGANISED FLUIDS.

gative properties ; these during the first days of the life of the
infant are necessary, their continuance cannot but impair its
strength and health.

Recurrence of Colostrum.

M. Donne has established the interesting fact that milk
which has entirely lost the character of colostrum, and which
has reached its perfect maturity, may again pass into the
state of colostrum at any period during the course of lac-
tation.

Thus the milk which had at one time presented the con-
stitution of perfectly formed milk has been seen by M. Donne
to acquire gradually that which is indicative of the colos-
trum, it becoming viscous, and the globules contained in it,
instead of floating freely and singly in the serum, uniting
with each other, forming irregular masses, the granular and
mucous corpuscles at the same time being present in it in
considerable quantities.

In the instances in which the recurrence has been observed,
engorgement of one or both of the mammary glands has usually
preceded it.

When but one gland is affected, the milk of that gland
only presents the characters of colostrum, that of the opposite
side retaining its usual properties and constitution.

The recurrence of the colostrum would appear to depend,
as a cause, either upon lesion of the mammary gland, or upon
a deranged or vitiated condition of the health.

Influence of prolonged Retention of the Milk on its
Constitution.

M. Peligot has made the observation, important in a prac-
tical point of view, that the milk which has been allowed to
remain for a long time in the breast becomes thin and watery,
an effect which is contrary to that which occurs in reference
to most other secretions of the economy, the urine and the
bile, the density of which is heightened by retention.

MILK. 165

Thus if the milk abstracted at one time, and which has
been long secreted, be divided into three parts, each being
received successively into a distinct vessel, the first milk will
seem to be poor and watery, the second more rich, and the
third the most so of the entire. The first portion is to be
regarded as that which has been longest formed, and the
third as the most recently secreted.

The knowledge of the above fact leads to one practical re-
sult in the case in which the milk is too rich for the digestive
powers of the child ; thus by allowing such milk to remain
for a longer period than usual in the breast, a fluid of lighter
quality and less abounding with nutritive principles will be
obtained.

A second effect of prolonged retention or engorgement of
the milk in the breast is to occasion the aggregation of the
globules into masses. (See Plate XI V.^. 6.)

Pus and Blood in the Milk.

Having now described those constituents by the combina-
tion of which milk is formed, as well as the several conditions
in which these may be encountered, we may next refer to
those structures which occasionally occur in milk as the result
of disease.

Thus the corpuscles of both pus and the blood are some-
times encountered in the milk, those of the former fluid
occurring much more frequently than those of the latter.

The puriform matter which issues from the breast in cases
of abscess of that gland is made up of a mixture of pus and
milk globules, with occasionally blood discs. (See Plate XV.

fig- i.)

But both pus and blood corpuscles, the latter very rarely,
may be contained in the milk which issues from the breast
through its natural channels.

I was so fortunate as to meet with an excellent example
of blood in the milk, the occurrence of which is so rare that
Donne, at the period of the publication of the " Cours de
Microscopic," and with all his researches on the milk, had

166 ORGANISED FLUIDS.

never encountered a single instance of such pathological
alteration in the human subject. The case in which this oc-
curred was that of a young woman confined of her first child ;
the milk not appearing at the usual time the friends became
anxious, and one of them, more officious and more ignorant
than the rest, had the nipples drawn with such vigour and
effect as to cause the extraction of a liquid half blood and
half milk. (Plate XV. Jig. 2.) The occurrence of blood
corpuscles in the milk can only take place as the consequence
of a rupture of some of the smaller blood vessels which are
distributed through the mammary gland.

The above facts clearly show the impropriety of applying
an infant to the breast in cases of inflammation and suppu-
ration in that organ.

Not the least difficulty need be experienced in the detec-
tion of pus and blood corpuscles in the milk, their form and
structure being so totally dissimilar to those of the proper
milk globules. Re-agents also affect the different kinds of
corpuscles differently. Thus the milk globules are soluble
in ether, which does not materially affect the pus and blood
corpuscles, the latter of which is dissolved by acetic acid, and
the former only by the caustic alkalies.

The Milk of Syphilitic Women.

M. Donne has made repeated attempts to discover in the
milk of women labouring under syphilis in different forms,
some element which would account for the transmission of
the affection from the mother to the infant. These endea-
vours were, however, entirely fruitless ; nor is this result other
than what might have been anticipated, for it is scarcely to
be supposed that the venereal virus exists anywhere in a
tangible form, and if it really does so, it would still be a
matter of impossibility to point out the channels by which
any solid matter could make its way through the system and
mingle with the secretion of the mammary gland.

MILK. 167

The Milk of Women in the Case of the premature Return of
their Natural Epochs.

The milk of women in whom the natural periods have re-
turned during the course of lactation, has likewise been
carefully examined. Except in a single instance, however, it
has not been found to present any thing remarkable in its
characters. In the case referred to, it had degenerated to the
condition of colostrum, and contained the granular colostrum
corpuscles.

THE MILK OP UNMARRIED WOMEN.

The breasts of many women who have not been married
are frequently found to contain an abundance of milk, and
from those of most, more or less of a milky fluid can be
obtained.

This milk exhibits all the characters of colostrum, con-
taining even the peculiar corpuscles which distinguish that
condition of the milk ; it is therefore, like the first milk, to be
regarded as an imperfectly elaborated substance.

THE MILK OF WOMEN PREVIOUS TO CONFINEMENT.

The breasts of most women during the last few weeks of
gestation contain more or less milk, which also presents all
the characters of colostrum.

The quantity of milk contained varies greatly; in some
cases a few drops of a milk-like fluid only can be obtained ;
in others it is more abundant ; and again, in other instances,
it is still more plentiful, and rich in quality.

The question may be asked, does there exist any relation
between the quantity and condition of the milk before con-
finement, and its state when it has arrived at perfection after
this event has occurred ? In other terms, can one pronounce,
by the milk in the breasts, beforehand, "whether a woman
will have a sufficient quantity of milk to nourish her infant ?

168 ORGANISED FLUIDS.

This question, which so often presents itself to the con-
sideration of the medical practitioner, M. Donne has discussed
at some length, and to it he replies thus.

" The secretion of the mammary gland," he says, " is after
confinement in constant relation with the state which it pre-
sents during gestation, so that it is possible to know in ad-
vance, by the observation of its characters during the last
months of pregnancy, what its condition will be when it shall
have acquired all its activity after parturition." * This law,
he states, is so general that in the sixty observations which
he has made on women of all ages and temperaments, he has
met with but two or three exceptions.

Pregnant women Donne divides into three classes, founded
upon the characters presented by the colostrum during the
last months of gestation.

1st. Those in whom the secretion is small, and the viscous
liquid contains scarcely any milk globules, mixed with a
very few colostrum corpuscles.

2nd. Those in whom the colostrum is more or less abun-
dant, but poor in milk globules, which are small, ill-formed,
and containing also colostrum and mucous corpuscles.

3rd. Those in whom the colostrum is very abundant, rich
in milk globules, which are of good size, and unmixed with
any other corpuscles save those proper to the colostrum.

Now the indications to be deduced from the different states
of the colostrum just described are —

That the first state appertains to women in whom the
secretion of milk after childbirth is either very little, or in
whom there is produced but a serous milk, poor in nutritive
elements, and therefore insufficient for the nourishment of
the child.

That the second condition indicates those in whom the
secretion of milk after confinement is either small or abundant
in quantity, but which is always poor and serous.

That the third state of the colostrum belongs only to such
women as have an abundant supply of milk of good quality.

* Cours de Microscopie, p. 406.

MILK. 169

THE MILK OF WOMEN WHO HAVE BEEN DELIVERED, BUT
WHO HAVE NOT NURSED THEIR OFFSPRING.

The mammary gland of women who have borne children,
but who have not nursed them, is frequently found to con-
tain milk many months after confinement.

This milk always presents the characters of colostrum.

MILK IN THE BREASTS OF CHILDREN.

A milk-like fluid can frequently be expressed from the
breasts of infants and young children, both male and female.

This fluid, examined microscopically, has been found to
exhibit all the characters of ordinary milk ; and, in some
cases, the colostrum corpuscles have even been detected in it.

DIFFERENT KINDS OF MILK.

The milk of one mammiferous animal resembles so closely
that of another that it is often a matter of impossibility to
distinguish, either with the naked eye or by means of the
microscope, the different kinds of milk.

The milk of the ass may, however, be generally known by
its watery aspect, its bluish tint, and its lightness ; that of
woman by the promptitude with which the layer of cream is
formed upon it ; but it is, above all, by the taste that the
several kinds of milk are characterised : thus, the taste of the
milk of the cow can scarcely be confounded with that of the
ass or goat, nor can the flavour of the milk of woman be
mistaken for that of any of these.

The microscope aids but little in the discrimination of the
different kinds of milk : the globules of the milk of the goat
are certainly smaller than those of the other species named,
and those of the ass are less numerous ; nevertheless these
characters are so little constant that they are not, in many
instances, sufficient to distinguish them from the milk of the
row or of woman.

170 ORGANISED FLUIDS.

The number of globules contained in the milk of different
animals doubtless varies considerably ; but there is as much
variation in this respect as in those just referred to ; and,
therefore, this difference is not sufficient to distinguish the
several kinds of milk.

RELATIVE PROPORTIONS OF THE ELEMENTS OF MILK.

Chemical analysis indicates a very great variety in the
relative proportions of the different nutritive ingredients of
milk ; and this, not merely with respect to the milk of dif-
ferent animals, but also in reference to that of the same
species, and even of the same individual, at different times.

The truth of these remarks will be evident from an ex-
amination of the following analyses : —

Analysis of the milk of woman by Peyen.

Butter - 5-16

Sugar and cream - 7 '80
Analysis of the same by F. Simon.

Water - - 88-06

Caseine - 3'70

Sugar - 4-54

Butter - 3-40

Salts, extractive matter, £c. - - 0-30

100-00

Analysis of the milk of woman, the cow, the goat, and the
ass, by Meggenhofen, Van-Stiptrian, Liuscius, and Bonpt,
and Peligot.*

Woman.

Cow.

Goat.

Ass,

Butter

- 8-97

2-68

4-56

1-29

Sugar
Casine

- 1-20
- 1-93

5-68
8-95

9-12
4-38

6-29
1-95

Water

- 87-90

84-69

81-94

90-95

* This analysis is copied from the " Cours de Microscopic" of Donne.

MILK. 171

It will be seen from the above analyses that the milk of
woman is the richest in butter, while that of the ass contains
the smallest amount of that element.

The assertion made by Donne, that the quantity of butter
in the milk of the same species stands in relation with that
of the other essential ingredients of the milk, although sup-
ported by the researches of Peyen and Peligot is contradicted
by those of F. Simon. According to the analyses of Simon,
the quantity of sugar is greatest immediately after delivery,
a few days being passed this diminishes, and the amount of
caseine, which was at first very small, undergoes a gradual
augmentation. The butter Simon considers to be the most
variable element of the milk, its variations not being reducible
to any law.

The relative proportion of the different ingredients of the
milk of animals may be modified, and almost altered, at will,
by the adoption of a certain regimen.

GOOD MILK.

The purity and the richness of milk were formerly estimated
by its specific gravity, which is about 1 *032 ; if the milk was
poor in cream, or if it was diluted with water, it was sup-
posed that the gravity of the fluid would be in the first case
increased, and in the second lessened.

The cream being the lightest element of the milk, its
deficiency or its abtraction would, of course, increase the
density of the remaining fluid, and the addition of water,
after the removal of the cream, which is also of less weight
than milk which is even pure and rich, would, of course,
raise the gravity of the milk either up to or even beyond its
natural weight.

Now, /the abtraction of the globular element of the milk
and the addition of water are the two frauds most frequently
had recourse to ; and they are of such a nature as to elude
detection by reference to the specific gravity of the milk,
when they are both put in practice in combination.

p 2

172 ORGANISED FLUIDS.

The specific gravity test of the purity and richness of milk
is, then, one which is fallacious, and therefore but of very
little value.

It has been proposed by M. Quevenne, not merely to esti-
mate the specific gravity of milk, but also to measure the
layer of cream which forms upon it by repose. This in-
genious method is scarcely more to be depended upon than
the preceding, and is put at fault by the fact that the addi-
tion of water favours the ascension of the cream.

Thus, the layer of cream formed on milk to which water
has been added will be thicker than that of unadulterated
milk, this effect being the consequence of the lessened specific
gravity resulting from the addition of the water.

Donne has made the statement, which is borne out by the
analyses of MM. Peyen and Peligot, that the globular or
buttery element of the milk stands in relation, in the milk of
the same species or animal, though not in different species,
with the other nutritive ingredients of milk, the cheese and
the sugar.

The analyses referred to are the following : —
Milk of woman analysed by M. Peyen.

Butter - 5-16 5-18 5-20

Sugar and cheese - 7'80 • 8-10 9'80
Milk of asses analysed by M. Peligot.

Butter - - 1-55 1-40 1-23 1-75 1-51

Sugar and cheese 10-11 7-97 7'84 8-25 7'80

Donne, therefore, proposes to estimate the purity and the
richness of milk by means of the globular element contained
within it. The eye alone will, in some measure, indicate the
number of globules contained in the milk; for, since the
opacity of milk is due to the presence of the globules, it may
be concluded that the milk which is white and opaque is
rich in globules, while that which is watery and transparent
is poor in the same.

The microscope, however, is a more certain means of de-
termining the number of the globules, although by means of
this instrument we can only arrive at an approximative
knowledge of their amount.

MILK. 173

In order to estimate as nearly as possible the number of
globules existing in the milk, M. Donne has invented an ap-
paratus which he has termed a lactoscope. By means of
this instrument the milk can be examined in very thin
layers, and in proportion to the opacity of the milk spread
out into such layers, so will be its richness, the deeper the
stratum the richer the milk.

There is one fallacy attending the use of this instrument
which requires to be noticed : this, however, is one which has
reference to its employment in testing the quality of the
milk of the cow, the ass, and the goat, and not of the milk
of woman.

The milk of commerce is frequently adulterated with sub-
stances such as chalk and flour, which are intended to
heighten its colour and opacity ; the presence of these then
in the milk would, to a certain extent, lessen the value of
the opinion to be deduced from an examination of the milk
with the lactoscope of Donne.

The effect, however, of the admixture of chalk and flour in
heightening the opacity of milk is not so considerable as
might be supposed, and this is especially found to be the
case when it is spread out in thin layers as in the lactoscope.
Moreover, the presence of an insoluble substance in the milk
might be detected by means of the microscope.

Applied to the examination of the milk of woman, the
lactoscope would not be subject to the above fallacy.

Having now shown that the globules constitute an im-
portant element of the milk, and the methods by which their
number may be ascertained, we may, in the next place, de-
scribe more particularly the qualities of good milk.

Healthy milk may be defined to be an alkaline fluid,
having a specific gravity of about 1-032, holding in suspen-
sion numerous perfectly spherical and discrete globules,
soluble 'in ether, and therefore of a fatty nature, — and in
solution cheese and sugar, together with various salts.

If, on the contrary, the milk be viscous pr acid, if the glo-
bules be ill formed or few in number, if they adhere together
in masses and do not roll freely and separately in the serum,

p 3

174 ORGANISED FLUIDS.

«

if also this contain the colostrum corpuscles, then the milk is
either imperfectly elaborated or diseased.

Whenever the proper globules of the milk occur abund-
antly, are of the usual size, and are equally diffused through-
out the serum, we may conclude that the other nutritive
elements of the milk are likewise present in due proportion.
(See Plate XIV. fig. 1.)

It must be held in mind, however, that the milk of dif-
ferent animals does not contain normally the same relative
amount of nutritive ingredients : thus the milk of woman is
especially rich in cream, while that of the goat and ass is but
poor in that element.

POOR MILK.

Not unfrequently the milk is found to contain a less quan-
tity of globules than ordinary : the milk in which a deficiency
of its globular element exists appears watery and trans-
parent, and is also usually of greater specific gravity than
good milk. (See Plate XIV. fig. 2.)

This condition of the milk is one of its most common as
well as most serious states in its consequences to the child.

At the same time that the milk is poor in globules or in
cream, the serum may be either deficient in quantity, or it
may be in excess.

In either case, such milk, whether it be human or not, is
deficient of the amount of the nutritive ingredients necessary
for the growth and development of the child, which instead
of increasing in size, daily diminishes, becoming faded and
emaciated. In the instances in which milk containing a
superabundance of serum is received into the stomach, that
organ becomes distended and weakened by its engorgement
with a fluid the digestion of which brings with it little or no
nourishment.

An infant whose strength is reduced by the poverty of the
milk given to it, is not unfrequently the subject of diarrhoea,
which still further lessens its powers.

MILK. 175

RICH MILK.

An opposite condition of the milk to that just described
frequently exists, viz. that in which its nutritive principles
are in excess, a fact which is most readily ascertained by an
examination of the state of the globular element of the milk :
this being superabundant, it may, as already shown, be con-
cluded that the sugar and cheese likewise occur in unusual
quantities. (See Plate XIY. Jig. 5.)

This condition of the milk is not to be regarded as an alter-
ation of its qualities, but merely as an exaggeration of them ;
nevertheless, it is one which is often incompatible with the
well-being of the child. This rich milk is often too strong
for the digestive powers of the child, whose nutrition in con-
sequence suffers : it, moreover, is sometimes the occasion of
colic and diarrhoea.

The state of the milk just noticed, and its consequent
effects upon the child, may be modified and even entirely
remedied by a judicious regulation of the diet as well as by
permitting the milk to remain in the breast for a considerable
time, the effect of which retention is to render it more watery ;
the infant, also, should not be allowed to take the breast except
at long intervals.

At the same time that the globules are more numerous in
milk which is very rich, they are also larger. The size of
the globules is likewise found to undergo an increase from the
first days of lactation, and this increase continues for some
months afterwards : thus, the globules of the third month
are larger than those of the first month, and those of the
sixth month still larger, the number of the very small
globules having diminished very considerably. The increase
in the size of the globules referred to, is not, however, so uni-
form or so constant as to allow of the determination from it
of the age of the milk.

p 4

176 ORGANISED FLUIDS.

ADULTERATIONS OF MILK.

There are but few articles of general consumption more
adulterated, and on which more frauds are practised, than
the milk.

The more usual substances employed for the purpose of
adulteration are water, flour or starch, chalk, and the brains
of sheep ; of these, water is the one which is most frequently
had recourse to, and which is the most difficult to detect.

The effect of water in altering the specific gravity of milk
has already been referred to ; and it has been shown that the
result of its addition to milk, a portion of the cream of which
has been abstracted, is to restore the specific gravity which
usually belongs to it.

Donne has shown that however much the gravity of milk
may vary, that the density of the serum of the milk is almost
constant. This fact is interesting and important, for by a
knowledge of it the deterioration of milk by its admixture
with water or with some other substance of the same density
with it may be ascertained. The serum is constantly heavier
than water : adulteration with it would then cause the serum
to exhibit a less specific gravity than that which should
properly characterise it ; the conclusion to be deduced from
this circumstance being that the milk has been deteriorated,
most probably, by the addition of water.

The adulterations with flour and sheep's brains are readily
detected by means of the microscope. The fraud by the former
may be recognised by the peculiar form of the flour granules,
as well as by the action of iodine upon them (See Plate
XV. ^/z*/. 6.) ; and that by the latter may be distinguished by
the detection, in the fluid, of more or less of cerebral struc-
ture, and especially of the nervous tubuli.

The chalk in the milk is readily revealed by its efferves-
cence with hydrochloric acid, as well as by its weight, which
causes it to subside at the bottom of the vessel containing the
milk.

MILK. 177

FORMATION OF BUTTER.

Several explanations have been proposed with the view of
determining the exact cause of the amalgamation of the
cream globules with each other, and the formation of butter.

Some have supposed that the trituration to which the
globules are subject in the churn determines their union and
incorporation with each other ; but it is known that the
amalgamation is not a gradual process, as it would be were
their union to depend upon trituration, but that it takes place
in a manner almost instantaneous : moreover, agitation might
fairly be presumed to have a contrary effect on the globules,
which participate in the properties of oil, and that it would
cause their further subdivision.

A second hypothesis conceives that a chemical alteration
in the condition of the globules is determined by the presence
of the air : this has been shown to be erroneous by the fact
that butter will form in vacuo.

A third theory presumed that an acid state of the milk
always preceded the formation of the butter : this notion is
disproved, since butter is formed of cream, the alkalinity of
which is purposely preserved by the addition of soda or any
other alkali.

Donne thus explains the formation of butter : " The butter
globules," he says, " are surrounded in the cream by cheese in
a viscous state : this matter isolates the globules the one from
the other, and is opposed to their union. The churning
coagulates the cheese in which the globules are imbedded,
and, once separated from this, the grease globules unite and
agglomerate together easily."

It is doubtful how far this explanation, though more satis-
factory than its predecessors, really accounts for the in-
stantaneous formation of the butter.

178 ORGANISED FLUIDS.

MODIFICATIONS EXPERIENCED BY MILK ABANDONED TO
ITSELF, AND IN WHICH PUTREFACTION HAS COM-
MENCED.

The first change which the milk undergoes subsequent to
its abstraction from the system is that which has already
been referred to, and which consists in the separation of the
globular or buttery element of the milk from its other con-
stituents, and its ascension to the surface of the fluid, where
it. forms the layer of cream ; this change in the arrangement
of the components of the milk is determined by the lighter
specific gravity of the proper milk or butter globules.

All the milk globules do not, however, ascend and join
those which constitute the cream : it is chiefly the larger ones
which do so, the smaller remaining diffused through the sub-
jacent milk, to which they impart the degree of opacity which
belongs to it.

These smaller globules are not, however, equally scattered
through the skimmed milk, the greater portion of them being
spread through the upper stratum of it, and the lower ap-
pearing almost clear and transparent, containing but few
butter globules, and these the smallest, as well as the minute
cheese globules already described.

These changes consist merely in a different disposition of
the normal constituents of milk, and are unaccompanied by
any alteration in the constitution of its elements. The next
series of alterations have reference to the decomposition of
the milk, and are attended by changes in the actual state and
composition of the milk.

The first change experienced by the milk indicative of
commencing decomposition is that from an alkaline to an
acid condition. This acidity, slight at first, goes on in-
creasing until at length other alterations are produced ; thus,
the layer of cream becomes thicker and thicker, condenses
itself into a mass, and finally presents almost the appearance
of butter; at the same time the cheese is coagulated and
precipitates itself to the bottom of the liquid : a portion of it,

MILK. 179

however, frequently remains suspended in the milk, in conse-
quence of its retaining a number of butter globules, which
lessen its specific gravity. Soon, however, other changes
show themselves, still more indicative of putrefaction: the
layer of cream swells up, becomes more yellow, and a fungus
springs up upon its surface, the Penicillum glaucum. This at
first presents the appearance of white velvet ; but afterwards
as soon as the fungus has reached the period of fructification
it assumes a green colour.

The idea of M. Turpin, that this fungus had its origin in,
and was developed from, the milk globule, scarcely requires
a serious refutation.

At the same time the odour of the milk undergoes a com-
plete change : sweet when it is fresh, it becomes acid as it
decomposes, and gives out more especially the smell of
cheese.

Examined with the microscope, in addition to the fungus
alluded to above, numerous infusory animalcules will likewise
be detected.

Now the changes above described, and which are expe-
rienced by the milk of every animal, will be more clearly un-
derstood if the milk be previously filtered, and the butter and
the serum being obtained separately, those alterations which
ensue in each be noticed.

It will be observed, that it is the butter, or non azotised
substance, which undergoes the acid fermentation, and on
which the fungi are principally and most generally developed.

The serum, on the contrary, becomes alkaline and exhibits
the ammoniacal or putrid fermentation, this depending upon
the azotised principle which it holds in solution, viz. the
cheese.

It will be remarked, also, that the serum in changing does
not exhibit the striking odour of cheese which the milk itself
gives 'out under the same circumstances, and from which it
may be concluded, that a certain amount of butter is neces-
sary to produce the peculiar smell of cheese.

The phenomena to which the putrefaction of milk give
rise result, then, from two kinds of fermentation ; the acid, in

180 ORGANISED FLUIDS.

which the buttery element of the milk is concerned, and the
alkaline, resulting from the decomposition of the caseine.

THE OCCURRENCE OF MEDICINES, ETC. IN THE MILK.

The extreme rapidity with which the formation of milk from
the blood is effected is most surprising, and is only equalled
in the animal economy by that with which the urine is itself
secreted.

The rapid secretion of milk from the blood serves to ex-
plain the almost immediate appearance in the former fluid of
various chemical re-agents and articles of food introduced
into the system through the medium of the stomach.

Thus, many articles taken as food, or as medicine, have
been detected in the milk a few minutes after they have
been received into the stomach. The colouring matter of
madder root, the odorous principles of garlic, turpentine, &c.,
neutral salts, nitrate of potassium, — have all been encountered
in the milk.

These particulars show the necessity of great precaution
in the prescribing of remedies for a nursing mother, and ex-
plain the great susceptibility of children at the breast to the
influence of the medicine administered to the parent.

THE SEMEN. 181

ART. VI. THE SEMEN.

The seminal fluid, arrived at its perfect state, as when it
is ejaculated, is not a simple liquid, the secretion of a single
organ, but is compounded of the several products furnished,
though not in an equal proportion, by the testicle, the epi-
didymis, the vas deferens, the prostate gland, the glands
of Cowper, the vesiculae seminales, and the follicles of the
urethra.

But the spermatic fluid is also in another sense a compound
product ; thus, like the fluids which have already been de-
scribed, it is made up of a liquid and a solid element, the
latter consisting of numerous organised particles suspended in
and diffused through the former ; these particles are of more
than one kind, and may be divided into those which are
essential and those which are non-essential : those which be-
long to the first category are the spermatozoa, the seminal
granules, and the spermatophori ; and those which appertain
to the second, are the mucous corpuscles and epithelial scales :
these last constituents occur but seldom, and are difficult to
discriminate from the seminal granules and the spermato-
phori.

The spermatic fluid, resulting from the above combination
of solid and fluid elements, is then usually a thick semi-
opaque and gelatinous-looking substance, of a greyish, whitish,
or yellowish tint, and endowed with a peculiar and penetrating-
odour, which Wagner states does not belong to the sperm
previous to its departure from the testicle itself.

It is, above all, the spermatozoa, from the liveliness of their
motions, the variety of their forms, the peculiaritv of their
developments, and their functional importance, which impart
interest to the study of the spermatic fluid, and which the
microscope has shown to occur in it in such vast numbers.

182 ORGANISED FLUIDS.

SPERMATOZOA.

The spermatozoa * are the most distinctive, as well as the
most interesting, constituent of the semen, and once detected,
the nature of the fluid under examination can no longer be
doubted.

Each spermatozoon consists of two portions, an expanded
part, to which has been assigned the several names of " disc,"
" head," and " body," and an attenuated extremity, which is
called " tail."

The spermatozoa present great varieties in size and form :
these variations are for the most part constant in a natural
family and genus, and are always so in a simple species : thus
a knowledge of the particulars of form and size of the seminal
animalcules is frequently sufficient to distinguish many groups,
genera, and individuals from each other : spermatozoa are,
therefore, capable of affording assistance in classification.

Form.

In the class Mammalia especially, with which, in this paper,
we are chiefly concerned, the spermatozoa vary greatly in
shape; but in several of the more natural groups of that
class, one determined form and magnitude may be detected
throughout the different species constituting such groups.

* In reference to the discovery of the spermatozoa, the following passages
are contained in Leeuwenhoek (Opera, t. iv. p. 57.) : — " N. Hartsoeker
(Prseven der Doorsichikunde, s. Specimina dioptrices, p. 223.) says that
he made known the spermatic animalcules in 1678, in the " Journal des
Savants." I attribute the discovery to Hamm. He brought me in 1677
some gonorrheal matter, in which he found animalcules with a tail, which,
according to him, were produced by the effect of decomposition. I after-
wards examined fresh human semen, and I then perceived the same
bodies. They were in motion, but in the liquid portion ; in the thick
part they remained immoveable. They were smaller than the corpuscles
of the blood, rounded, obtuse before, pointed behind, with a tail five or
six times as long as the body." The description of Leeuwenhoek appeared
for the first time in the Philosophical Transactions, December 1677 and
January and February 1678.

THE SEMEX. 183

In man, and in some animals which approach near to man
in their organization, the spermatozoa are small, the head or
disc is ovate, the narrow extremity forming the summit of
the disc, and the tail, proceeding from its broader end, di-
minishes in size from its origin to its termination, which is
so fine, that its extreme point can with difficulty be discerned.
(See Plate XVI. fig. I.)

In the rat and in the mouse the seminal animalcules are
large, and their form peculiar ; the head is half sagittate, and
moveable upon the tail, which is long, and attached not to
the base of the arrow-like head, but to its side : frequently
the head is curved, in which case it resembles the blade of a
curved scimitar. (See Plate XVII.)

In the guinea-pig also, the magnitude of the spermatozoa
is great, and the shape remarkable : in this animal the head is
large, ovate, concave on one side, and convex on the other,
the tapering and elongated cauda arising from the narrow
end of the oviform head, which may be compared in form to
a mustard -spoon. (See Plate XVII.)

In birds two singular types occur, the one characteristic
of the order Passeres, the other typical of the Rapaces,
Scansoresy GallincK, Grallce, and Palmipedes. In the first,
the head of the spermatozoon is elongated and spiral, resem-
bling a corkscrew ; the number of coils and the acuteness of
the angles vary in different species ; usually two, three, or
four turns are described ; the attenuated and greatly produced
tail proceeds from the finer end of the spire, and between it
and the body no exact line of demarcation exists. (See
Plate XVI. Jig. 2.) In the second, there is a distinct divi-
sion into head and tail, and the former is elongated, as in
the order Passeres ; but, in place of being spirally coiled, is
straight, the tail arising abruptly from the body, is of great
tenuity, of equal diameter, and the length exceeding but little
that of the body.

The various forms assumed by the spermatozoa amongst the
other vertebrate and invertebrate animals it is unnecessary
here to describe : the shape of those, however, belonging to
the Tritons and Salamanders, from their great peculiarity,

184 ORGANISED FLUIDS.

may be briefly noticed. At the junction of the body and
tail of each spermatic animalcule an enlargement exists, the
excessively attenuated caudal extremity being curved spirally
round the body.

The effect of water in modifying the form of the sperma-
tozoa is remarkable, it frequently causing them, when ap-
plied in large quantities, to coil up and form themselves into
rings : this effect of the application of water is supposed to
depend upon some hygroscopic property possessed by the
spermatozoa.

Frequently the spermatozoa are seen to occur on the field
of the microscope grouped together in bundles, the bodies
all lying one way, and fitting by their concavities into each
other. (See Plate XVII.) This arrangement, as Avill be
seen hereafter, is connected with the evolution of the sper-
matozoa.

Occasionally, in man and other animals, the head and tail
are separated from each other, and lie apart ; this separation
is doubtless either the result of violence or the effect of de-
composition. Henle * states that he has seen the tail move
independently of the head.

Size.

Much diversity exists in the size of the spermatozoa in
different animals, although but little difference can be de-
tected in those of the same individual. Wagner, however,
has made the observation that their magnitude varies greatly
in different individuals of the same species. These varia-
tions are, however, of course confined within certain narrow
limits. In the Mammalia the spermatozoa of man are amongst
the smallest, while those of the guinea-pig and rat are
amongst the largest hitherto discovered. In the birds the
seminal animalcules of the order Passeres are very large, and
especially those of the chaffinch.

* Anat, Gen. p. 534.

THE SEMEN. 185

Structure.

When first the spermatozoa were discovered and their
lively motions observed, much reluctance was entertained to
regard them as independent animals or beings ; and upon
this point, even amongst modern physiologists, there is still
an absence of accord, some of them attempting to explain
the movements exhibited on purely physical principles.

Not many years ago a celebrated and talented continental
observer thus expressed himself in terms more ingenious than
accurate in reference to the nature of the spermatozoa : —

" When we place upon the object-glass of the microscope the
semen of a subject who enjoys all the energy of his generative
faculty, we there see corpuscles more or less rounded or oval,
having a sort of caudiform appendix : some have made animal-
cules of these little bodies, since they have seen that they
move, and have believed to have recognised in their move-
ments a determined direction, a character which they thought
could only appertain to animated beings. And as amongst
the microscopic animalcules which they knew there are those
which are provided with a tail more or less prolonged and
more or less dilated, they have assimilated to them the little
animalcules of the semen, and have made them Cercaria.

" But you are about to see that the conformation and the
movements of the corpuscles in question may be explained
naturally, without our being obliged to have recourse to
the hypothesis of which I have spoken. It is certain that
we find in the sperm little gelatiniform masses more or less
rounded, oval, and having one part prolonged into the form
of a tail, like, in a word, to the drawings which Buffon
and many other observers have given us of the pretended
spermatic animalcules. These little masses float in a material
less consistent than themselves, and even fluid. But at first
their oval form results evidently from the manner in which
they reflect the light, and afterwards as the fluid in which f hey
are suspended — a fluid which is itself more or less viscous —
attaches itself strongly to them, it results that in the mi-
crosco-chemical movements which take place in the sperm,

Q

186 ORGANISED FLUIDS.

the corpuscles which it incloses seem to have a tendency to
escape from the kind of glutinous material which contains
them. This material, seeking, if we may express it thus, to
retain them, accompanies them to the situation only where
they find themselves to be arrested by a filamentous pro-
longation, which presents sufficiently well the appearance of
a tail, and even of a flexible tail, by reason of the lateral
movements which the little body makes in its progression.
There is merely in all this, as you see, a mechanical pre-
nomenon, and, in the movement which there takes place, but
a physical effect of the contact of two materials of different
densities ; contact which provokes these materials to mingle
together and to form but one, as arrives at the end of a time
more or less long. Abandon the semen to itself, taking care
that its watery part cannot evaporate by placing it in an
atmosphere saturated with humidity, at the end of a certain
time the mixture of the two materials will be complete, and
you will perceive no longer any thing but a homogeneous
fluid ; the pretended animalcules have disappeared.

" If we wish to show you at the same time veritable
microscopic animalcules and the little gelatiniform masses
which move in the vehicle of the sperm, you will find a great
difference between the first and these last. I may fortify
my opinion on this subject with that of Buffon and Spal-
lanzani, who have denied that the masses of which I speak
were animalcules.

" Amongst the persons who have admitted the existence of
these beings, there are those who have carried their preten-
sion so far as to class them in genera and species by taking
the form of the dilated extremity for the principal zoological
character. Somemicrographers, also, remarking the differences
in the corpuscles of the sperm, according as one procures this
liquid from the testicle, the vesiculas seminales, or after its
ejaculation, have pretended, from that circumstance, to de-
scribe a series of evolutions in the developement of these
so-called Cercariae. They have told us that these animals do
not exist in the product which occupies our attention at the
moment that it is formed ; that they appear but in the vesiculse

THE SEMEX. 187

seminales ; that in these they are as yet but simple globular
animals ; that in their progress they become developed by
the production of their caudal prolongations. Lastly, it has
been pretended, — doubtless with the design of marking with
ridicule the opinions which we have reported, — it has been
pretended, I say, that the spermatic infusorias became amongst
us, for example, veritable homuncules, having little anus,
little legs, &c. But this is sufficient in itself to put us on
our guard against an optical illusion which has unfortunately
seduced a great number of persons, from Leeuwenhoek, one
of its first favourers, even to MM. Prevost and Dumas, who
in these later days have still maintained the existence of the
spermatic animalcules."

In the present day, it is needless to enter into any refutation
of the above views ; it cannot, however, fail to be observed
by the reader, that they are weakest just where they should
exhibit the most strength, that is, in the explanations given
as to the form and motions of the spermatozoa.

Those physiologists who deny the animality of the sper-
matozoa would, of course, be very reluctant to admit of the
existence of any thing like organization in them ; while those,
on the other hand, who entertained a belief in their animal
nature would be most anxious to establish the fact of such
organization.

The greatest possible difference of opinion then exists as to
whether the spermatozoa are organized or not, and if organized
as to the extent to which they are so.

In the centre of the disc of the spermatozoa of man and some
other animals a light spot has been observed ; this some have
imagined to be a stomach ; others, again, have rejected this
idea, and thus account for its presence : the disc, they say, is not
of equal thickness, and, like the red blood corpuscle, is thinnest
in the centre, and which part, therefore, exhibits a lighter
tint than the remainder : this latter view is most probably
the correct one. The first opinion is entertained by Valentin,
and the second by Dujardin and Hcnle. Muller conceived
the spot in question to be a nucleus.*

* Mullor's Physiology, p. 635.
Q 2

18-8 ORGANISED FLUIDS.

Leeuwenhoek remarked upon the spermatozoa of the ram
two clear spots ; at another time, numerous little points in
the interior ; a third time, two semilunar strise, united by a
longitudinal line: he figures also in those of the rabbit a
multitude of little globules, one of them, larger than the
rest, being placed near the tail.

Grerber assigns a most complex structure to the spermatic
animalcules of the guinea-pig, describing stomachs similar
to those of the polygastric infusoria^, an anus and sexual
apparatus ; and, conceiving the existence of these several
parts to have been established, he thus expresses himself in
reference to the nature of spermatozoa in general : " The
compound organization of the seminal animalcules and their
production by no equivocal generation, but m particular
sexual organs, and by the means of ova, to all appearance
proclaim their affinity to the Entozoa."*

Valentin f has described an almost similar amount of
organization in the spermatozoa of the bear: " The clear
spermatozoa of the bear," he writes, " which in external form
approach those of the rabbit, present distinct traces of in-
ternal organization, to wit, an anterior and posterior haus-
tellate mouth, and internal cavities or convolutions of an
intestine."

Again, Dujardin J has described and figured certain irre-
gular knots and lobular enlargements at the root of the tail
of the human spermatozoa; these have been noticed by
"Wagner, who believes that they occur only as the effects of
certain alterations experienced by the animalcules in conse-
quence of their long stay in urine, and especially when
this fluid has contained at the same time a quantity of puri-
form sediment.

Wagner likewise points out, as occurring now and then,
but by no means constantly, a small prominence or trunk-
like process situated on the anterior part of the body of human
spermatozoa : this, or a similar projection, he also states to be

* Gerber's General Anatomy, translated by Gulliver, p. 337.

t Repertorium, 1837.

% Ann. des Sciences Nat. viii. p. 293. plate 9. 1827.

THE SEMEN. 189

much more regularly present in the seminal animalcules of
the bat, in which they occur as pointed spines. The same
observer has, moreover, noticed upon one or two occasions
the caudal end of the body to be double, bifid, or forked,
and once too the body appeared to be double, as in a bi-
cephalous monster. *

The above comprise all the particulars which have hitherto
been promulgated in reference to the organization of the
spermatozoa ; scarcely any one of them has however been
sufficiently established : we are therefore not authorised to
receive them as proved, and to build any reasoning upon
them : the most which we are warranted in deducing from
them amounts to this, that traces of organization have been
discovered in the spermatozoa, the precise nature and extent
of which have not as yet been satisfactorily determined.

Notwithstanding his observations given above, Wagner f
states that he has been utterly unable, after varied, repeated,
and long continued examination, to discover true internal
organs in the spermatozoa. Siebold J has also been equally
unsuccessful in his endeavours to detect such, as also Henle §
and Kcelleker.

The determination of the fact that the spermatozoa are
possessed of even the smallest amount of organization, would
involve their classification in the animal kingdom, and the
description of the different forms which occur as so many
distinct species.

The view of the animal nature of the spermatozoa would
appear to gather strength, and to admit almost of positive
demonstration, by reference to their very remarkable motions.

MOTIONS OF THE SPERMATOZOA.

It is impossible that anything can convey a more just idea
of life f than the spectacle of a drop of the seminal fluid in
which the spermatozoa are in active and ceaseless motion.

* Elements of Special Physiology, pp. 10. 16. 0 f Loc. cit. p. 17.
I Siebold in Weigman's Arcliiv. 1838.
§ Anatomic Generate, t. vii. p. 531.

190 ORGANISED FLUIDS.

Sometimes, indeed, when the semen is thick and tenacious,
the movements of the contained spermatozoa are but feeble,
the density of the liquor seminis presenting too great an
impediment to the free motion of these minute creatures.

Often, however, in such cases, when the fluid has been
diluted with water or with some other liquid, as serum
or milk, of less density than itself, the spermatozoa, being
now set at liberty, will frequently be seen to resume their
locomotive powers, and to move about with the greatest
activity. All the spermatozoa, however, contained in a drop
of semen which has undergone dilution will not start into
motion at once ; many of them will remain for a time per-
fectly motionless, and then suddenly, and, as it were, by an
act of volition, begin to move themselves in all directions.

Mode of Progression.

The motions of the spermatozoa are effected principally by
means of the tail, which is moved alternately from side to
side, and during progression the head is always in advance.

The strength of the spermatozoa is considerable, it en-
abling them, when they are immersed in either blood or
milk, to cast aside, with the greatest ease, the globules which
may present themselves to impede their progress.

The spiral spermatozoa of the Passeres advance by a move-
ment of rotation of the body, the tail remaining extended
and motionless, acting rather as a rudder than as an organ
of locomotion. The spermatozoa of the other orders of birds,
and which consist of a cylindrical body to which a short and
attenuated tail is attached, " scull themselves forward with
their tails, either striking them slowly and with wide sinu-
osities, or more quickly and shortly, as when a whip is
shaken ; they thus advance in circles with a quivering mo-
tion, holding the body extended in a straight line, although
they also now and then bend this in various directions from
side to side."*

* Wagner's Elements, p. 18.

TH-E SEMEN. 191

The spermatozoa of the tritons and salamanders usually lie
coiled up in the form of a ring, and seem to spin round
as upon a pivot ; at the same time a second wavy and
tremulous motion, like that produced by ciliae, is observed ;
this arises from the rapid rotatory or spinning movement of
the very delicate tail with which the spermatozoa of these
animals are furnished, and which is wound spirally round the
body. Wagner at one time entertained the notion, which
however he subsequently discarded, that the wavy motion
referred to was produced by a ciliary apparatus. Some^
times the coiled spermatozoa have been seen to unrol them-
selves and to cross the field of the microscope with slow ser-
pentine motions.

Furthermore, in the various motions executed by the sper-
matozoa they exhibit all the characters of volition ; thus they
move sometimes quickly, at others slowly, alter their course,
stop altogether for a time, and again resume their eccentric
movements. These movements it is impossible to explain
by reference to any hygroscopic properties which may be in-
herent in the spermatozoa, they appear to be so purely
voluntary. A strong argument, therefore, in favour of the
independent animality of the spermatozoa may be derived
from a consideration of the nature of their motions.

Duration of Motion.

The length of time during which the motions of the sper-
matozoa continue, either after the escape of the seminal fluid,
or after the death of the animal, varies very considerably ;
thus it is maintained for a longer period in warm weather
than in cold, and when the semen is retained within its
natural reservoirs than when it is removed from those re-
ceptacles. The spermatozoa of some animals also preserve
their powers of locomotion for a longer period than those of
others ; thus the seminal animalcules of bjrds die very soon
after the death of the bird ; according to "Wagner, frequently in

192 ORGANISED FLUIDS.

from fifteen to twenty minutes * ; occasionally, nevertheless,
the spermatozoa have been found moving in birds which have
not been opened until some hours have elapsed after death :
those of the Mammalia have been observed in motion for a
very long period after the removal of the semen from the
testicle, and after the death of the animal ; but it is in fishes
that the spermatozoa retain their powers of locomotion out
of the body for the longest period, even for many days.

According to Dujardin f , the spermatozoa live thirteen
hours in the testicles of the mammalia after the death of the
animal.

LamperhoffJ has found living semen in the vesicuta se-
minales of dead men, in which the spermatozoa retained the
power of locomotion for twenty hours.

Wagner § has observed them exhibiting motion at the end
of twenty -four hours.

Donne || states that he has watched their movements for
an entire day, and that he has observed them in motion even
on the second day.

It is, above all, in the place of their final destination that
the spermatozoa live for the longest period ; thus, Leeuwen-
hoek first, and other observers subsequently, have discovered
them in a living condition in the uterus and Fallopian tubes
of a bitch seven days after connexion IF, and Bischoff** has
found them alive eight days after intercourse in the rabbit.

The great length of time during which, under certain cir-
cumstances, the spermatozoa retain the faculty of locomotion,
furnishes another strong argument in favour of their inde-
pendent vitality.

Effects of Reagents.

The seminal animalcules retain their locomotive powers
for a very long time in fluids of a bland nature, for ex-

* Wagner, loc. cit. p. 21. f Annales des Sciences Nat.

\ Diss. de Vesical. Semin. § Loc. cit, p. 22.

|| Cours de Microscopic, p. 284. ^[ Opera omnia, t. 1. b. p. 150.
** Muller, Archiv. p. 16. 1841.

THE SEMEN. 193

ample, in blood, milk, mucus, and pus ; on the contrary,
in reagents of an opposite character, and in those possessed
of poisonous properties, they soon cease to move : thus, in
the saliva and urine, unless these fluids be very much diluted,
their motions are soon destroyed, and immediately cease in
the acids and alkalies, in alcohol, iodine, strichnine, and the
watery solution of opium.

The addition of water to the spermatic animalcules usually
produces a remarkable effect, increasing greatly for a time the
rapidity of their motions, which after the lapse of a minute
or two entirely cease ; this reagent, as well as the saliva,
exerts a further peculiar influence upon them, causing them
to curl up into circles or rings.

Poisons introduced into the system, and destroying the
life, are stated not to affect the motions of the spermatozoa ;
an assertion to be received with some degree of hesitation :
in cases of poisoning by prussic acid, I have usually found
the spermatozoa to be motionless even when viewed imme-
diately after death.

The urine has the property of preserving the spermatozoa
entire for weeks and months ; and Donne has detected them
in that fluid after an interval of three months.

The result, then, of the application of reagents, furnishes
an additional argument in favour of the animality of the
spermatozoa, and one which it would be difficult, if not im-
possible, satisfactorily to controvert.

SPERMATOPHORI.

The only essential solid elements contained in the seminal
fluid arrived at its perfect state, as in the vas deferens, and
when ejaculated, are the spermatozoa ; occasionally, however,
there are encountered in it, as non-essential constituents, mu-
cous corpuscles, epithelial scales, and the seminal granules :
the spermatic liquid, however, obtained from the body of
the testicle, contains not only the several structures already
named, but also minute and bright granules, and the com-

R 2

194 ORGANISED FLUIDS.

pound cells or spermatophori, the bright granules and the
seminal corpuscles probably represent stages in the deve-
lopment of the spermatophori.

The several structures now named are all occasionally met
with in the ejaculated semen ; their occurrence in it is to be
regarded rather as accidental than as essential ; the sperma-
tophori belong to the testicle, the tubuli seminiferi of which
in many cases are almost filled by them.

The spermatophori differ greatly from each other, both as
respects size and the number of secondary cells or nuclei
contained within them ; the smaller parent cells are about
TFO o °f an incn i*1 diameter in man, and contain usually but
a single nucleus, while the larger ones attain the magni-
tude of -Q^Q of an inch in breadth, and include not unfre-
quently as many as six or eight nuclei, or, more properly
speaking, secondary cells. Between the two extreme sizes
given, every gradation presents itself, and many spermatophori
contain but one, two, three, or four nuclei, which are the
numbers most frequently encountered.

The secondary cells, like the primary or parent ones, are
globular, and those contained within the same parent cell
are usually of the same dimensions ; the centre of these cells
occasionally presents a bright spot. (See Plate XVI. Jig. 1.)

Not unfrequently certain large and perfectly transparent
cells are encountered ; these are in all probability the older
spermatophori, the contents of which have been discharged.

It would appear, therefore, that the development and dis-
solution of the spermatophori are effected entirely within the
tubes of the testes.

Cells, which Wagner has denominated seminal granules,
occur, as already remarked, mixed up with the undoubted
spermatophori ; these first are smaller, and do not contain
nuclei ; whether they are really distinct from the latter, it is
not easy to determine. If but one kind of cell occurs in the
testicle, then a double function must be assigned to it : thus in
the first place, the secretion of the liquor seminis must be
effected by it ; and in the second, the development of the
spermatozoa occurs within its cavity ; in which case the sper-

THE SEMEN. 195

matophori would be the homologues of the cells of other
glands, only in so far as they discharge an analogous func-
tion, and are secreting organs ; in the ulterior office allotted
to them, that of being receptacles in which the spermatozoa
are evolved, they stand alone in the animal economy, and are
certainly without analogues in any other gland of the body.

It is most probable, however, that two kinds of cells
co-exist in the testes, the one secreting and corresponding
with the cells of other secerning organs ; the other kind,
of a peculiar nature, without parallel in the animal economy,
and devoted to the development of the spermatozoa.

DEVELOPMENT OF THE SPEKMATOZOA.

Not the least interesting part of the history of the sper-
matozoa is that having reference to their development.

Wagner was the first to state that the spermatozoa are
developed within the spermatophori just described.

This interesting discovery of Wagner has been amply
confirmed by the extended observations of Koelliker, Siebold,
Valentin, and Lallemand.

Wagner thus describes the evolution of the spermatic ani-
malcules in the spermatophori of a bird. " In the course
of their development, a fine granular precipitate is ob-
served to form between the included nuclei, by which
these are first obscured and then made to disappear, and
linear groupings are produced, which anon proclaim them-
selves as bundles of spermatozoa, already recognizable by
slight traces of a spiral formation of one extremity. (See
Plate XVI. fig. 2. y.) It were hard to say whether the fine
granular precipitate is to be regarded as the product of a
process of resolution occurring to the nuclei, or a new form-
ation; as also, whether the spermatozoa spring out of or
only in and amidst the yolk-like matter, or matter that is
at all events comparable to the yolk of eggs in general.
The vesicles now assume an oval form" (see Plate XVI.
fig. 2. 7i), the globules disappear, the granular contents

* 3

196 ORGANISED FLUIDS.

diminish; the seminal animalcules are well grown and lie
bent up within the cyst ; their spiral ends are more con-
spicuous. The delicate covering (involucrum) is now drawn
more closely around the bundle of spermatozoa it includes,
and where it covers their spiral ends anteriorly it assumes
a pyriform outline (see Plate XYI. Jig. 2. i), and at the
opposite extremity is perhaps at this time open ; but it is
difficult to speak decisively on this point. The cysts are
now very commonly bent nearly at right angles or like
knees, but at length they appear stretched out and straight,
and have attained their full size. (See Plate XVI. fig. 2. k.)
The capsules of these vesicles are at all times, and especially
towards the end of their existence, highly hygroscopic ; the
addition of a little water causes them to burst, the masses
of spermatozoa rolled up like a little skein of thread or
silk escape, and occasionally at this stage exhibit motions
individually, which, however, whilst the animalcules continue
in the ducts of the testes, are frequently not to be observed,
and are never either general or remarkable. The sperma-
tozoa, after the rupture of the cyst, advance in freedom to
the vas deferens." *

The process Wagner states subsequently to be precisely
similar in man and the Mammalia, although it is more
difficult to follow it in them.

The accuracy of the above account of the development
of the spermatozoa has been admitted by most other ob-
servers in all respects save one important one : thus
Kcelliker has shown that the evolution takes place in the
included or secondary cells, and not, as Wagner describes
it, in the spaces between these, a single spermatic animalcule
being formed within each ; the granules inclosed in these cells
disappear gradually as the spermatozoon assumes a definite
form, and Krelliker further supposes that these granules
constitute by their union with each other the substance
of the spermatozoa which escape from both the secondary
and primary cells by the rupture of their investing mem-

* Translation of Wagner's Elements, by Willis, pp. 25, 26.

THE SEMEN. 197

branes. When the spermatic animalcules have escaped
from the secondary cells, and these have disappeared, the
spermatozoa form a bundle which is still included within
the larger primary cell ; sometimes the seminal animacules
are irregularly disposed within its cavity, but more fre-
quently they are applied directly to each other, the heads
lying one way, and the tails in the opposite direction.
This disposition of them is often preserved even after their
escape from the spermatophori, during their stay in which
the spermatozoa usually remain quite motionless.

The interesting and important fact of the development of
the spermatozoa in the secondary cells, or ova, as they should
now be called, Krclliker first ascertained by the study of
their evolution in the guinea-pig*; subsequently, he extended
his observations, and found that the spermatozoa in man were
evolved in a manner precisely similar.

Valentin f during his inquiries observed masses of fila-
ments in the mother cells of the rabbit and bear, and Hall-
man | noticed the same thing in those of the rays ; he
does not however speak of the transformation of the included
nuclei or ova.

In the class of invertebrate animals, it is most probable
that a similar method of development prevails.

The spermatozoa are not encountered in equal numbers in
all parts of the testicle, the more remote convolutions of the
tubuli seminiferi containing chiefly the simple granular cells
and the spermatophori, while it is only in those which approach
near to the epididymis that they occur in any numbers ; in
this situation they usually lie immediately beneath the mem-
brane of the seminiferous tube, and external to the sperma-
tophori, their long axes being disposed in the direction of
that of the tube itself. In the vas deferens the spermatozoa
are present in vast numbers, and with scarcely any admix-
ture of /the other solid elements of the testes.

It is in the epididymis that the different stages of de-

* Beitrag. p. 56. tab. 11. fig. 20. f Report, p. 145. 1837.

t Muller, Archiv. p. 471. 1840.

R 4

198 ORGANISED FLUIDS.

velopment of the seminal animalcules are best seen side by
side.

The spring is by far the most suitable period for the
study of the development of the spermatozoa, and birds,
especially those of the order Passeres, present the best ex-
amples in which to trace their evolution, because in them the
seminal animalcules are large, and the reproductive function
is excessively active for a brief and determined period.

Wagner * has shown that from the commencement of
the time of moulting, and through the entire winter, the
testes of birds undergo an extraordinary degeneration, the
spermatozoa and the spermatophori being entirely oblite-
rated, and the volume of the testes reduced to at least the
twentieth or thirtieth of the size to which they attain in spring.
Thus the testis of the common chaffinch is in winter not
larger than a millet seed, while in spring it exceeds a pea in
size.

The same degeneration is doubtless experienced during
winter, although to a less extent, by most animals of the class
Mammalia.

THE SPERMATOZOA ESSENTIAL TO FERTILITY.

The spermatozoa do not exist in the testes of mammalia at
all periods of life : thus they do not make their appearance
in that organ in man until the period of puberty, and they
disappear gradually as old age advances. It is impossible
however to determine the time at which they are first de-
veloped, or at which they cease to exist in that organ, be-
cause the period of puberty differs in different individuals,
and some men are aged in constitution when others of the
same years are hale and robust. Certain it is, that some men
retain the power of engendering until a very advanced age, of
which fact the celebrated Parr presents a memorable example,
he having become a father at the extraordinary age of 142.

The number also of the spermatozoa contained in the
seminal fluid varies in different individuals, and is usually in

* Elements, pp. 28. and 29.

THE SEMEN. 199

proportion to the activity of the reproductive function, and
this again is dependent to a great extent upon the constitu-
tional powers as well as upon the mode of life.

The activity then of the reproductive faculty in man is in
many cases a good test of health.

The above few facts favour the idea of the essentiality of
the spermatozoa ; others however, of a stronger kind, still
remain to be mentioned.

Wagner has instituted some most interesting inquiries in
reference to the condition of the spermatozoa in male
hybrids, and especially in male hybrid birds, and he finds,
that in them the characteristic animalcules are either al-
together wanting, or occur but in small numbers, and are ill-
formed and ill-conditioned ; the hybrids in which the seminal
animalcules have been thus found to be absent or degenerated,
have been ascertained to be incapable of having offspring.*

Again, Leeuwenhoekf discovered living seminal animalcules
in the uterus and Fallopian tubes of bitches seven days after
connexion. J

Prevost and Dumas § have more recently made the same
observations at the same length of time after intercourse.

Siebold |] has detected the spermatozoa in a living state in
the uterus and Fallopian tubes eight days after connexion.

Lastly, Bischofflf and Martin Barry ** have observed the

* Loc. cit. pp. 30—34. f Opera omnia, p. 150.

j Leeuwenhoek signalised the discovery of the living spermatozoa in
the uterus and Fallopian tubes, in the following words : — " Nudo conspi-
ciens oculo, nullum masculum semen canis in ea esse dicere debuissem ;
at eandem mediante bono microscopic, summae mese voluptati immen-
sam viventium animalculorum multitudinem ; semen nempe canis mas-
culum contemplabar. His peractis, dictain aperiebam tubam, in fine suae
crassitudinis, ac ibidem quoque magnam seminis masculi canis contem-
plabar copiam, quod semen illic vivebat, et hoc modo quoque cum dextra
egi tuba, ac in eadem quoque immensam seminis viventis canis masculi
copiaiii'Observavi. . . . Materiam qua matrix concita est, observans
majorem adhuc viventium animalculorum copiam deprehendebam.

§ Annales des Scien. Nat. t. iii. p. 122.

|| Muller, Archiv. p. 16. 1841. ^[ Wagner's Elements, p. 66.

** Researches in Embryology, Second Series, Phil. Trans, p. 315.
1839.

200 ORGANISED FLUIDS.

spermatozoa not merely in the uterus and Fallopian tubes,
but also on the ovary itself.

From these facts it is therefore evident that the spermatozoa
are essential to fecundity, although the precise manner in
which they are so is still involved in the greatest obscurity.
It is supposed by some observers, that they make their way
into the ovum itself: this notion is as yet without evidence
to support it.

It would be most interesting to determine whether im-
pregnation could be procured by the artificial introduction of
semen, the animalcules of which were dead ; there is every
reason to believe that in the many cases in which the artificial
injection of the seminal fluid has been successful, the contained
spermatozoa were in a living condition ; and from all that is
yet known in relation to the animalcules, there is strong pre-
sumption to believe that the experiment referred to, viz. the
introduction of semen, the animalcules of which were dead,
would be unattended with success.

One remarkable experiment of Spallanzoni, however, de-
serves to be referred to. Most observers agree in saying, that
the spermatozoa of the frog die after some hours of immersion
in water. It is known, however, that Spallanzoni succeeded
in fertilising the ova of frogs with spermatised water, con-
taining three grains of seminal fluid to eighteen ounces of
water, thirty-five hours after the mixture had been prepared,
and this, in a chamber with the thermometer at from 17 to
19 degrees ; and again, that in an ice-house, the thermometer
being three degrees above zero, the spermatised water pre-
served its prolific power for fifty-seven hours.

Now, the tendency of this interesting experiment is cer-
tainly to prove the possibility of fertilisation occurring with
semen, the spermatozoa of which are dead: this inference
would appear however to be negatived by another ingenious
experiment of MM. Prevost and Dumas, who filtered the
seminal fluid and found that the fluid portion which passed
through the filter would not vivify the eggs, while the more
solid part, consisting of the spermatozoa, produced the results
peculiar to the seminal fluid.

THE SEMEN, 201

Jacob! succeeded in fertilising the ova of a carp with
semen which had been contained within the body of the fish
for four days ; but it is well ascertained that the spermatozoa
of fishes in general live for a much longer period than that
named. * Some have supposed that the only use of the sper-
matozoa is by their movements to hasten the advance of the
semen towards the Fallopian tubes.

PATHOLOGY OF THE SEMINAL FLUID.

The quantity of seminal fluid secreted varies greatly accord-
ing to the age and constitution of the individual. In young
men, and in those whose health is vigorous, the secretion is
rapid and abundant ; in the aged, and in those whose vital
powers are feeble, it is but slow and scanty. It is, however,
in severe states of disease that the amount of seminal fluid
secreted is greatly diminished, if the formation of it be not
in some cases altogether suspended for a time. Under the
influence of recovery, the quantity of semen formed again
undergoes an augmentation.

An inordinate secretion of the seminal fluid, as also its
prolonged retention in the testes, are sometimes the causes of
involuntary seminal discharges, which, however, are more fre-
quently occasioned by organic weakness, the result of over in-
dulgence.

If these emissions be very frequent, the ejaculated semen
will be found to be thin and watery, and to contain com-
paratively few spermatozoa.

It is unnecessary to describe here the destructive effects of
these emissions on the constitution.

It is often a matter of great importance to determine, in-
dependently of any revelation on the part of the patient,
whether in any particular case seminal effusions exist.

This fact, it is in the power of the microscope, according to
some observers, in all cases to declare with the most absolute
certainty.

* Several most interesting particulars in reference to artificial im-
pregnation are given in Wagner's Elements, chap. iii.

202 ORGANISED FLUIDS.

After each effusion of semen, in whatever way occasioned, a
certain amount of that fluid will still remain behind, adhering
to the surfaces of the urethra ; this, of course, contains the
seminal animalcules, which will be washed away on the first
passage of the urine through the urethra.

The great object, then, is to establish the fact of the ex-
istence of spermatozoa in the urine : this may be accom-
plished in two ways ; either by filtration or decantation, the
latter being perhaps the preferable method of the two ; the
spermatozoa, being heavier than the urine itself, always sub-
side at the bottom of the vessel, and where they may always
be found, if present in even the smallest numbers.

The urine, as already mentioned, has the property of pre-
serving the seminal animalcules, which may be detected in it
months after their discharge from the urethra.

M. Donne * states, that he has never succeeded in detecting

the seminal animalcules in the urine, unless as the conse-

_rquence of an emission of semen, and which may have occurred

either during connexion, in an involuntary manner, or through

•^masturbation. Now, if this be true, the occurrence of the

spermatozoa in the urine declares positively the fact, that

a discharge of semen has been sustained, and this particular

is often in itself sufficient to enable a medical man to form

an opinion of the case.

It seems to me, however, by no means sufficiently proved,
that an escape of the seminal fluid with the urine does not
take place independently of any distinct emission. I am in-
clined to think that such escape is an habitual occurrence
even with the most healthy, especially with the continent,
and that by it the surcharged testes are relieved whenever
requiring such relief.

This view is to some extent supported by the observations
of Dr. John Davy | and Wagner J : the former excellent
observer states that on examining the fluid from the ure-

* Cours de Microscopic, p. 318.

f Edin. Med. Surg. Jour. vol. ii. p. 50.

I Loc. cit. p. 21.

THE SEMEN. 203

hra after stool in a healthy man, he had always detected
permatozoa.

In connexion with the above few remarks on the pathology
of the semen, we may refer to the observations of Donne on
the effects of an exceedingly acid condition of the mucus of
the vagina, and a very alkaline state of that of the uterus
itself, on the vitality of the spermatozoa.

The mucus of the vagina, in its normal state, is slightly
acid, this degree of acidity being perfectly compatible with
the life of the seminal animalcules ; but Donne has shown
that under some circumstances, as from congestion, irritation,
or inflammation, this mucus becomes so strongly acid as
to destroy in a few seconds the vitality of the spermatozoa.

Again, the mucus of the uterus in its healthy state is
slightly alkaline, but not so much so as to exert any injurious
effects upon the spermatozoa ; in conditions of derangement
and disease, however, it becomes so alkaline, as Donne has
shown *, that in like manner with the acid mucus of the vagina,
it kills the seminal animalcules in a very short space of
time.

Now after what has been said and detailed in reference to
the essentiality of the spermatozoa, it can scarcely be doubted
that women whose vaginal and uterine secretions are so dis-
ordered, are inapt to conceive, and this from the effect of
their vitiated secretions upon the spermatozoa.

It would be interesting to determine whether the sperma-
tozoa are ever entirely absent from the semen of man : it is
very probable that in certain rare cases they are so, and from
the facts already ascertained there can be no doubt that
those individuals whose spermatic fluid is devoid of its
characteristic living element would be wholly incapable of
having offspring.

It is probable, that in the impotent the spermatozoa are
almost, if not entirely, extinct.

* Cours de Microscopic, p. 292.

204 ORGANISED FLUIDS.

APPLICATIONS OF A MICROSCOPIC EXAMINATION OF THE
SEMEN TO LEGAL MEDICINE.

The detection of the spermatic animalcules is frequently a
matter of high interest and importance in a medico-legal
point of view.

There are three classes of cases in which the microscope,
by revealing the presence of spermatozoa, is capable of for-
warding the ends of justice and of bringing conviction home
to the guilty.

1st. In cases of suspected violation.

2nd. In determining the nature of doubtful stains ob-
served on the bed-clothes, &c.

3rd. In unnatural offences.

With respect to those cases which come under the first
division, it may be observed that the medical testimony
on which these are usually decided is too often of such a
nature as to lead to the acquittal of a really guilty indi-
vidual; the medical man, judging merely from external
appearances, being compelled to give evidence either directly
favourable to the prisoner, or which is at best but of a
doubtful character.

In suspected violation, then, when the evidence to be
deduced from an outward examination is insufficient for the
formation of a satisfactory and decided opinion, the micro-
scope may frequently be employed with the greatest ad-
vantage.

If the offence imputed has been committed, and if con-
nexion has really occurred, then by means of this instru-
ment, provided too long a time has not elapsed from the
period of the occurrence, that is to say, a period not ex-
ceeding from twenty-four to forty-eight hours, the sper-
matozoa will be detected in the mucus, properly examined,
and obtained from the upper part of the vagina : now the
detection of these in such a situation is a demonstration that
intercourse has taken place.*

* Donne, in the Cours cle Microscopic, states that he has detected the
spermatozoa in the vaginal mucus of women admitted into the hospital,

THE SEMEN. 205

The examination of the urine of women whose persons
are suspected to have been violated would also frequently
furnish evidence of the fact by manifesting the presence in
it of the spermatozoa, which in its passage through the
vagina it had washed away from its walls.

With reference to the second class of cases mentioned,
those requiring for their satisfactory elucidation the deter-
mination of the nature of suspicious stains, here again, by
means of the microscope, evidence the most conclusive may
frequently be obtained.

Now, if the stains in question be formed by the seminal
fluid, and if they be not too old, the microscope applied
to them will detect in them the spermatozoa.

With regard to the length of time at which the sper-
matozoa may be detected in the matter of a stain, I have
reason to think that this has scarcely a limit : I have myself
noticed them in the semen several weeks old, and they then
appeared to have undergone scarcely a single appreciable
change, the spermatophori contained in the seminal fluid
being equally well seen.

In examining stains occasioned by the seminal fluid, it is
advisable to use the same precautions as those which wrere
pointed out in reference to blood stains, and to moisten them
with either serum or albumen.

The reader's imagination will suggest to him numberless
cases in which the determination of the nature of suspected
stains would be a matter of the utmost importance, and
would lead to the production of evidence of the greatest
consequence, and in no other way obtainable.

Lastly, with reference to the third class of cases, those of
unnatural offences : here also the microscope, by revealing
the presence of the spermatozoa in the rectum, or on some
other part of the body, may throw great light on occur-
rences,which otherwise would in all probability be buried in
complete oblivion and mystery.

in which instances it is most probable that connexion had occurred at
least some hours previous to admission.

206 ORGANISED FLUIDS.

An examination of this kind was assigned by the magis-
trates in France some years ago to two physicians, on the
occasion of an assassination in an hotel. A traveller
having been killed by a young man whom he had received
into his chamber during the night, justice was interested to
know whether semen would be found in the rectum or not. *

It is known that in death by hanging, an emission of the
semen usually occurs, and this, in the absence of other
proofs, has been adduced as a sign of death by suspension.
It would appear, however, that such an indication is not
without its sources of fallacy.

It is thus apparent that in the cases here referred to, the
microscope is capable of affording positive evidence of a most
important and conclusive kind ; on the other hand, the nega-
tive testimony deducible from its application in these cases
is not without its value.

* See Annales oT Hygiene Publique et de Medecine Legale, Paris, 1839,
L xxi. pp. 168. and 466.

207

UNORGANISED FLUIDS.

ART. VII. SALIVA. — BILE. — SWEAT. — URINE.

THE fluids comprised under the heading of UNORGANISED
FLUIDS differ from those of the first division, viz. the ORGA-
NISED, in that they do not contain, as essential elements,
organised structures ; solid organic particles are indeed
usually to be encountered in them, but these are to be re-
garded either as accidental or at all events as non-essential
adjuncts, and which appertain usually to the structure of
those organs from which the fluids have themselves pro-
ceeded.

The presence and nature of the solids contained in the
UNORGANISED FLUIDS serve to indicate to a considerable
extent the condition of the glands by which they have been
secreted, and thus frequently throw great light upon their
pathology.

There is, however, one kind of solid constituent which is
found almost constantly in these fluids, viz. the crystals of
various salts: these being however unorganised, their con-
sideration does not properly belong to a work devoted to
descriptions and delineations of organised tissues.

It is proposed, therefore, in order to render the application
of the microscope to human physiology and pathology as
complete as possible, to prepare a separate treatise on the
subject of the crystallisations formed in the various fluids,
&c. of tlie body, under the title of HUMAN CRYSTALLO-
GRAPHY.

We will now pass in review the fluids comprehended in
the division of UNORGANISED FLUIDS. In reference to
some of them but little remains to be said, as will have been

208 UNORGANISED FLUIDS.

inferred from a knowledge of their structureless character.
In the treatise on Crystallography, however, many interest-
ing and important details will be given.

The UNORGANISED FLUIDS comprise the saliva, the bile,
the sweat, the urine, and the gastric, pancreatic, and lacrymal
fluids ; these several fluids especially deserve the name of
secretions, since they are elaborated by large and complexly
organised glands.

THE SALIVA.

The saliva is a peculiar fluid secreted by the parotid, sub-
maxillary and sublingual glands, from which it is conveyed
by certain ducts into the mouth, where it becomes mingled
with the buccal mucus. The amount of saliva secreted
during the day is estimated at from ten to twelve ounces;
during salivation either spontaneous, or induced by mercury,
the quantity may exceed two or three quarts. It is worthy
of remark, however, that in these latter cases the mercury has
never been detected in the saliva.

Mitscherlich * made the following observations on a person
having a salivary fistula, and in whom the saliva could be
collected directly as it flowed from Steno's duct. He found
that there was no flow of saliva while the muscles of mastica-
tion and of the tongue were in complete repose, and all ner-
vous excitement avoided. He observed also, that during the
acts of eating and drinking, especially at the commencement,
the secretion was most abundant, and in proportion to the
stimulating nature of the food and the degree to which it
was masticated. From two to three ounces of saliva flowed
from the duct in the course of twenty-four hours.

The solid constituents of the saliva are composed of fat,
ptyalin, watery and spirituous extractive matters, a little
albumen, certain salts, a trace of sulphocyanogen, mucous
corpuscles, epithelial scales, and lastly, corpuscles resembling
mucous globules, which have been termed salivary corpuscles,

* Rust's Magaz., vol. xl.

THE SALIVA. 209

and which are probably nothing more than epithelial cells
in progress of development.

The salts of human saliva are, according to Mitscherlich,
chloride of calcium, lactates of soda and potash, soda either
free or combined with mucus, phosphate of lime, and silica.

In certain pathological states Simon detected in the saliva
acetic acid, and a considerable quantity of a substance re-
sembling casein.

The saliva is with difficulty to be obtained in a pure state,
it being generally intermixed with a greater or less quantity
of buccal mucus; now the normal reaction of the saliva is
alkaline, that of mucus acid ; it therefore follows, the fluids
in question being thus intermingled in variable proportions,
that the reaction presented by the fluid obtained varies ac-
cording to the relative quantity of each ingredient; thus
sometimes the saliva, when tested, will appear to be acid,
alkaline, or neuter, and the same will be the case with the
buccal mucus.

The true reaction of the saliva, then, can be ascertained
only by obtaining it unmixed with the mucus of the mouth,
and then testing it ; this may be effected by first washing
the mouth with water, and then applying the test paper to
the saliva as it flows from the orifice of its ducts.

The fact referred to of the admixture of the two fluids,
saliva and mucus, will serve to explain why test paper ap-
plied to the upper surface of the tongue exhibits frequently
an acid reaction, while that placed beneath it manifests the
presence of an alkaline fluid.

In morbid states the normal reaction of the saliva may
undergo a complete change, and it may become either neuter
or acid : this alteration has been especially observed to occur
in deranged conditions of the stomach, in acute rheuma-
tism, in cases of salivation, and, according to Donne, in
pleuritis, encephalitis, intermittent fevers, uterine affections,
and amenorrhea.

Acid saliva doubtless exerts a very injurious effect upon
the teeth.

The admixture of the saliva with mucus is readily shown

s 2

210 UNORGANISED FLUIDS.

by means of the microscope, which reveals the presence of
mucous epithelial scales in all stages of their development ;
as the scales found in the sweat are derived from the desqua-
mation of the epidermis, so are those of the saliva and mucus
from that of the epithelium.

The saliva as well as the sweat yields on evaporation
crystals of the various salts referred to in the analysis.

Blood corpuscles are sometimes present in the saliva and
mucus ; these proceed usually from the gums.

The uses of the saliva in the animal economy are classified
by Dr. Wright as follow : —

Active. 1. To stimulate the stomach and excite it to ac-
tivity by contact. 2. To aid the digestion of food by a
specific action upon the food itself. 3. To neutralise any
undue acidity of the stomach by supplying a proportionate
alkali.

Passive. 1. To assist the sense of taste. 2. To favour
the expression of the voice. 3. To clear the mucous mem-
brane of the mouth, and to moderate thirst.

THE BILE.

The bile, like the unorganised fluid already described, pre-
sents but little of interest to the microscopist in its normal
state.

It happens, however, occasionally, when it has been re-
tained in the gall-bladder for a long time, in consequence of
which it has become inspissated, that it does contain solid
and coloured particles.

These particles have been noticed by Scherer* and also by
Dr. H. Letheby of the London Hospital, who was so con-
siderate as to transmit, for my examination, a portion of in-
spissated bile, containing them, as also plates of cholesterine,
in great numbers.

The bodies in question consist of two parts, an external
colourless investing portion, and an internal coloured and
granular matter ; this disposition of the colouring matter im-

* Untersuchungen, &c., p. 103.

THE SWEAT. 211

parts to them the aspect of " pigment cells," which, in
fact, Scherer considers them to be.

There are but three kinds of cells, which, if cells at all,
they could be by any possibility, viz. liver, epithelial, or pig-
ment cells ; now, they are certainly neither of the first two
mentioned, as may be inferred from the dissimilarity of size,
appearance, and structure with these ; and they are as surely
not " pigment cells," because such structures do not enter
into the organisation of the liver.

It is then conceived, that these cell-like bodies are not
true cells, but are to be regarded as masses of concrete
mucus enclosing more or less biliary colouring matter ; the
great differences observed in their form, size, and general
appearance are all opposed to the notion of their being
definitely organised cells.

The meconium of infants very generally contains the cell-
like bodies described, together with intestinal mucus, cunei-
form epithelium, and occasionally cholesterine in a crystal-
line form.

THE SWEAT.

The sudoriparous glands, distributed over the whole sur-
face of the body, constantly secrete a very considerable
quantity of watery fluid : this fluid passes off usually in the
form of an insensible vapour ; in some cases, however, as
under high external temperature, active exercise, and in
certain stages and forms of disease, it collects on the skin in
the form of drops, which, in drying up, deposit their solid
constituents over the whole extent of the cutaneous surface :
it is then more particularly termed sweat.

Many attempts have been made to determine the amount
of fluid passing off by the skin ; the average quantity, accord -
ing to Seguin, amounts to about twenty-nine ounces of
fluid, the maximum to five pounds, and the minimum to
one pound, eleven ounces, and four drachms.

The amount of solid constituents carried off with the fluid
is, comparatively, very small, not exceeding in the twenty-

s 3

212 UNORGANISED FLUIDS.

four hours seven or eight scruples ; the remainder being
merely water, retaining in it carbonic acid and nitrogen, the
quantity of the former gas being increased by vegetable
diet, and the amount of the latter by an animal regimen.
Simon has established the existence, in normal sweat, of —

1. Substances soluble in ether : traces of fat, sometimes
including butyric acid.

2. Substances soluble in alcohol: alcohol extract, free
lactic or acetic acid, chloride of sodium, lactates, and acetates
of potash and soda, lactate or hydrochlorate of ammonia.

3. Substances soluble in water : water extract, phosphate
of lime, and occasionally an alkaline sulphate.

4. Substances insoluble in water : desquamated epithelium,
and after the removal of the free lactic acid by alcohol,
phosphate of lime with a little peroxide of iron.

The quantity of fluid exhaled is subject to very great
variations ; thus it is increased by a dry and light atmosphere,
while it is diminished by a damp and dense condition of the
air. It is at its minimum at and immediately after meals,
•while it is at its maximum during the actual period of
digestion. The cutaneous perspiration is in antagonism with
the urinary secretion ; thus an excessive secretion of urine
diminishes that of the skin, and a diminution of the activity
of the kidneys is usually followed by an augmentation of
that of the sudoriparous glands.

But little of interest, in a microscopic point of view,
attaches to this fluid; the only solid organic constituent
contained in it being detached scales of epidermis, which
is ever undergoing a process of destruction and renewal;
these scales, therefore, do not form part of the sweat, but
become mixed up with it in a secondary manner.

The copious formation and discharge of the cutaneous
fluid which occur under certain circumstances, thus do not
merely afford a relief to internal organs, but serve also, by
detaching and washing away the older and useless cells, to
cleanse the epidermis, and to render this more efficient as an
evaporating surface.

The crystals formed on the evaporation of the sweat, in

THE URINE. 213

states of health and disease, have been but little studied ; it
is probable that a knowledge of them would lead to the dis-
covery of some facts of interest.

The cutaneous fluid, it is known, is in health acid ; there
are some situations, however, in which it is constantly
alkaline, as in the axillae, about the genital organs, and
between the toes ; this, probably, arises from its admixture
with the secretions of the small follicles which are situated in
those parts.

The sweat, like the urine, is to be regarded as a cleansing
fluid, the system being through it relieved of certain surplus
and effete matters.

The pathology of the sweat is but little known : albumen
has been observed in it by Anselmino, in a case of febris
rheumatica, and Stark states, that it may be met with in the
sweat in gastric, putrid, and hectic diseases, and also on the
approach of death. The amount of acetic acid, ammonia,
and the salts, may all be increased. Uric acid and quinine
have been found in the sweat, the latter preparation being of
course at the time administered medicinally.

THE URINE.

Few fluids have been more studied of late years by the
microscopist than the urine ; this has arisen from the
elegance of form, variety of composition, and important
character of the numerous crystalline deposits which are
formed in it in states of health and disease, and which can
be satisfactorily determined only by the aid of the microscope.

The great advantage of the application of the microscope
over that of chemical tests to the study of the urine is, that
the indications which it affords are not merely certain, but
also prompt and facile, while the results obtained through
the agency of chemistry, although not less certain, are often
tedious and difficult.

The description of the various crystals formed in the urine
is reserved for another occasion ; in this place will be noticed

s 4

214

UNORGANISED FLUIDS.

only the organic constituents which occur in normal and
abnormal urine.

In order that the pathological alterations to which the
urine is liable may be more clearly understood, it will be
advisable, first, to describe the appearance and the constitu-
tion of healthy urine.

Healthy urine, when first passed, is a limpid fluid of an
amber colour, emitting a peculiar odour, exhibiting an acid
reaction, and having a specific gravity of about 1011.

Abandoned to itself, it soon loses its limpidity, becomes
troubled, and putrifies more or less quickly, according to its
chemical constitution, and the state of the temperature.

The following is Berzelius' analysis of healthy urine,
and with which all other subsequent analyses have been
found to agree to a very considerable extent : 1000 parts
contained, —

Water -

- 933-00

Solid residue
Urea -
Uric acid

Free lactic acid, lactate of am-
monia, alcohol, and water extract
Mucus

Sulphate of potash
Sulphate of soda
Phosphate of soda
Biphosphate of ammonia
Chloride of sodium
Chloride of ammonium -
Phosphate of lime and magnesia -
Silicic acid

It will be seen from the above analysis that healthy urine
does not contain the nitrogenised principles albumen, fibrin,
or casein, which are encountered so frequently in urine
voided in disease.

The only solid organised constituents which are constantly
encountered in healthy urine, are mucous corpuscles and epi-

67-00

30-10

1-00

17-14

0-32

3-71-

3-16

2-94
1-65
4-45
1-50

Fixed
> salts,
15-29.

1-00

0-03

THE URINE. 215

thelial scales ; these do not form part of the urine, but belong
to the structure of the mucous membrane of the bladder and
urethra, and both of them may be detected with the greatest
facility by the microscope. On account of their greater
specific gravity, they subside at the bottom of the vessel
containing the urine, where they may, at most times, be
procured for examination.

Occasionally, however, in the urine of man, under the cir-
cumstance already referred to in the article on the semen, the
spermatozoa are present in the urine also.

PATHOLOGY OF THE URINE.

The organic principles contained in diseased urine may be
divided, firstly, into those which are usually encountered in
that fluid in a state of solution, but which do yet, under
certain circumstances, assume the solid form ; and secondly,
into those which being definite organisms, occur only in a
solid condition. Albumen, fibrin, casein, and fat, belong to
the first, and the blood and pus corpuscles to the second
division.

Albuminous Urine.

Albumen is frequently present in the urine in disease ; it
has been noticed to occur especially in Bright's disease of the
kidney, and in the urine passed after scarlatina.

If the albumen be present in any considerable quantity,
nitric acid or bichloride of mercury will cause a precipitate,
and the urine will become turbid on the application of heat,
and deposit flocculi of coagulated albumen.

The colour, specific gravity, and reaction of albuminous
urine are various ; thus it may be either light or dark coloured,
it ma^ be of high or low specific gravity, it may exhibit either
an acid or an alkaline reaction, or it may be neutral.

When the albumen is small in quantity, heat is the most
efficient test for its detection ; it is only when the urine
manifests a decided alkaline reaction, that nitric acid is pre-

216 UNORGANISED FLUIDS.

ferable, the albumen being held in solution by the free
alkalies.

Urine may, however, become turbid from the application
of heat, even when no albumen is present : this arises from
precipitation of the earthy carbonates; in these instances,
the addition of nitric acid will immediately disperse the
cloudiness, and the reapplication of heat will not occasion
any further precipitation.

Dr. Gr. O. Rees has observed that the urine of persons
who have been taking cubebs or balsam of copaiba is ren-
dered turbid by nitric acid, although it contains no albumen :
this urine, however, is not affected by heat.

From the facts contained in the two preceding paragraphs,
it follows that a precipitate might possibly ensue on the ap-
plication of heat, and by the addition of nitric acid, and yet
no albumen be present in the urine.

If the precipitate yielded by nitric acid, added to urine
impregnated with the active principles of cubebs or copaiba,
be examined with the microscope, it will be found to consist
of minute oil bubbles, which are of course readily soluble
in ether.

Fibrinous Urine.

Fibrin has been encountered in the urine independently
of the other constituents of the blood : Zimmerman * has
described seven cases of fibrinous urine.

Such urine, if the fibrin existed in it in any quantity,
would coagulate or form a clot.

It is necessary in these cases not to confound mucus with
fibrin ; the former, under the microscope, exhibits the well-
known mucous corpuscles, while the latter appears either
filamentous or simply granular.

Fatty Urine.

The urine may contain fat, either separately or conjointly
with albumen, or with casein, and probably also sugar : the

* Zur Analysis und Sunthesis der pseudoplastischen Prozesse, Berlin,
1844. p. 129.

THE URINE. 217

urine holding fat in a free state may be called fatty ; that in
combination with albumen chylous ; and lastly, the urine in
which fat occurs in connexion with casein and sugar may be
denominated milky urine.

Fatty urine has been observed to occur frequently in per-
sons labouring under phthisis ; the fat, as the liquid cools,
forming a thin pellicle on its surface, the nature of which
may be at once ascertained by the microscope, which, if it be
really fatty, will reveal the presence of innumerable fat
globules.

Cases have been recorded in which the quantity of fat
has been so considerable that it could be detected with the
naked eye.

Chylous Urine.

Chylous urine is a white semi-opaque fluid, and contains
both fat and albumen ; the former may be detected by means
of the microscope, and the latter will be coagulated by heat,
by nitric acid, and the bichloride of mercury. Examined
microscopically, the coagulated albumen exhibits a granular
texture.

This form of urine has been observed principally in cases
of gout.

Milky Urine.

True milky urine is of very rare occurrence, there being
but two or three well-authenticated cases of it recorded ;
urine containing the constituents of chyle having doubtless
been described, in many instances, as milky urine.

The fat in milky urine occurs in combination with casein,
and probably with sugar also.

The fatty constituent may be detected as in the pre-
viously described urines, the fatty and the chylous, by
means of the microscope, and the casein will be precipitated
by the addition of a little acetic, dilute -Sulphuric, or hydro-
chloric acid, the flocculi of which, examined microscopically,
will exhibit a granular, and even in many cases a globular

218 UNORGANISED FLUIDS.

constitution ; they will contain also a greater or less number
of fat globules.

Urine containing casein in solution may be distinguished
from albuminous urine by the application of heat, which in
the latter will occasion a precipitate, none being formed in
the former, unless indeed a considerable quantity of nitric
acid be also present in the urine, when a temperature of 104
Fah. will be sufficient to occasion the precipitation of the
casein.

It is not to be supposed by the use of the term milky urine,
that the milk, as such, ever exists in the urine, and that it
finds its way there from the mammary gland by metastasis ;
the utmost that is to be inferred from the existence of the
principal elements of milk in the urine is, that the kidney,
in place of the mammary gland, has separated those elements
from the blood.

Excess of Mucus in the Urine.

In catarrhus vesicce, an affection to which old persons are
particularly liable, mucus is secreted in considerable quanti-
ties, and is voided with the urine.

This mucus subsides to the bottom of the vessel, is semi-
opaque, thick, and ropy ; examined with the microscope, mu-
cous corpuscles and epithelial scales are encountered in it.

In those cases in which the urine is very alkaline, the
mucus is observed to be particularly tenacious and thready :
this condition results from the action of the free alkalies con-
tained in the urine upon the constitution of the mucus.

Blood in the Urine.

Blood is frequently contained in the urine and voided
with it ; thus it is frequently encountered, in greater or less
quantity, in the following cases, — in inflammation of the kid-
neys, in injuries of those organs, or of the bladder itself, in
cases of stricture from the introduction of a catheter, from
the passage of renal or urinary calculi, and lastly, from chronic
disease of the kidneys and bladder.

THE URINE. 219

The best test of the existence of the blood in the urine is
the detection of the blood corpuscles by the microscope;
blood, however, may exist in the urine, and yet no cor-
puscles be detected, these having been dissolved by the acids
of the urine. Failing, however, to detect the blood discs,
if blood really be present, then the albumen, fibrin, and
hematin will still remain, and may be distinguished by suit-
able reagents.

From the colour of urine no conclusion can be formed as
to the existence of blood in it, as urine of a deep blood colour
is sometimes met with, which on examination is found not to
contain any trace of blood.

Pus in the Urine.

It has already been stated in these pages that no absolute
distinction exists between mucus and pus ; and, therefore, it
follows that it is in most cases impossible to determine, with
any degree of certainty, whether pus exists in the urine or
not.

If, however, the sediment rendered with the urine want
the tenacity of vesical mucus, and contain the granular cor-
puscles common to mucus and pus, there is reason to suspect
that the fluid in question is really purulent.

The diagnosis will however be greatly assisted by refer-
ence to the history and symptoms of the case ; thus if there
be rigors and hectic fever, the probability of the existence of
pus will be much strengthened.

There is one circumstance which requires to be mentioned,
and which greatly increases the difficulty of discrimination
between mucus and pus. In some cases of purulent urinary
deposits the urine is alkaline ; now the effect of the action of
alkalies on pus is to convert it into a transparent and tena-
cious substance in every respect resembling mucus, and
which therefore cannot be distinguished from it.

There are but few details interesting to the microscopist
connected with the Gastric, the Pancreatic and the Lacrymal

220 UNORGANISED FLUIDS.

fluids ; it will therefore be unnecessary to treat of them at
any length. It is to the chemist and physiologist chiefly
that the gastric fluid is interesting. They all, however, but
especially the gastric and the lacrymal secretions, contain
mucous corpuscles and epithelial scales, derived from the des-
quamation of the epithelium of the surfaces by which they
are secreted, and over which they pass.

Obs. — At page 144. the opinion is attributed to Mr.
Addison, that the white corpuscles of blood, mucus, and pus
contain filaments, whereas it would appear from a closer ex-
amination of the text, that the statement of that gentleman
only goes to the extent of asserting, that the fluid inclosed in
those corpuscles resolves itself in its escape into the filaments,
of which the brinous portions of blood, mucus, and pus are
under certain circumstances observed to be constituted.

221

PART II. THE SOLIDS.

THE division of the various constituents of the animal fabric
into the two orders of FLUIDS and SOLIDS, although a very
ancient one, is yet, to a certain extent, arbitrary and arti-
ficial. The truth of this observation is rendered apparent
on reference to the several fluids, the description of which
has just been brought to a conclusion, and all of which con-
tain suspended in them, either as essential or as accessory
elements, various solid and organised particles: the liquid
portion of some of these compound fluids exhibiting also a
distinctly organised constitution, as, for example, the liquor
sanguinis and the fluid parts of mucus and of pus.

The distinction referred to is not however without its use,
and is sufficiently well founded to serve the purposes of clas-
sification.

Of the SOLIDS themselves it is unnecessary to make any
formal subdivisions: they will simply be treated of in the
order of their natural relationship with each other.

Thus the various solid structures entering into the constitu-
tion of the animal organism will be described consecutively as
follows, each forming the subject of a distinct article : Fat,
Epithelium, Epidermis, Pigment Cells, Nails, Hair, Cartilage,
Bone, and Teeth; the various Tissues, the Cellular, under
which head Ligaments and Tendons will be described, the
Elastic, the Muscular, and the Nervous, including the de-
scription of the Brain and Nerves; the Glands, Vessels,
Membranes; and, lastly, the Pathology of the Solids, will
be treated of.

222 THE SOLIDS.

ART. VIII. FAT.

THE transition from the fluids to the solids would appear to
be a very easy and natural one through the substance about
to be described : thus fat bears an evident relation to both
the former and the latter, remaining during life in a soft and
semi-fluid state, and after death becoming hard and solid ;
it is, however, to the milk globules amongst the fluids that it
manifests the closest affinity, the fat vesicles, especially those
of early life, and the milk globules resembling each other in
form, in appearance, and in the manner in which re-agents
act upon them.

Fat is made up of the aggregation of a number of globules
or vesicles, which some deem to be true cells, and which are
held in juxta-position by intersecting bands of cellular tissue;
these vesicles have a smooth surface, semi-opaque texture,
and they reflect the light in the strongest manner.

Contents. — The contents of fat vesicles usually present a
homogeneous appearance, sometimes nevertheless, as when
undergoing decomposition, and when they have been subjected
to pressure, they exhibit a granular aspect ; these contents
are of an oily nature, and chemists have detected in the lard
of the pig the organic products, oleaine, stearine, margaric
acid, a yellow colouring matter having the odour and the
nauseous taste of bile, and the chemical salts, chloride of so-
dium, acetate of soda, and traces of carbonate of lime and
oxide of iron. It is probable that of these constituents the
presence of the chloride of sodium depended on the mode of
preparation of the lard.

Form. — The form presented by the fat vesicles is various,
but is usually either globular, oval, or polygonal. The first
shape is encountered in the fat of young animals especially
(see Plate XVIILj^. 1.); the second in that of adults (see
Jig. 2.) ; and the third in situations where the fat is sub-
jected to considerable pressure and on solidification after

FAT. ' 223

death. The fat vesicles of the pig are described as being
elongated and kidney-shaped. This shape, however, is of
rare occurrence, and cannot be regarded as the ordinary
and characteristic form, which is most generally more or less
spherical or oval. Raspail, observing this exceptional form,
was led to institute from it an erroneous comparison between
fat vesicles in general and the starch granule.

Size. — The fat vesicles of the adult are usually several
times larger than the solid corpuscles of any of the fluids
described, the blood, mucus, and milk: the size of the fat
vesicles in any given quantity of fat is not uniform ; but, like
the globules of milk, varies exceedingly, the dimensions of
the larger vesicles surpassing several times those of the
smaller.

One exceedingly interesting law has been observed in re-
ference to the size of fat vesicles ; thus it has been ascer-
tained that their average magnitude increases from infancy
up to adult age : in accordance with this law the fat cells of
an infant will be found to be several times smaller than those
of a full-grown person, and those of a child again of an in-
termediate size. This law will be apparent from an examin-
ation of the figures given. (See Plate XVIII.)

Colour. — The colour of fat is subject to considerable
variations, but it usually exhibits a tinge, more or less deep,
of yellow. The fat of young animals is usually of a lighter
colour than that of the full-grown and aged ; this may be
seen by a comparison of the fat of an infant with that of an
adult, or of the fat of the calf with that of the ox ; in the
former it is almost white, while in the latter it frequently
exhibits a deep and golden hue. The differences of colour
referred to doubtless denote differences in the relative pro-
portion of the different constituents of fat.

In some animals, also, fat of various bright colours is
encountered, especially in Birds, beneath the skin of the beak
and of the feet ; in the Crustaceae and in some of the Reptilia.
In the Triton the fat is of a deep orange colour, approaching
to red. The coloration of the iris of birds depends, accord-

224 THE SOLIDS.

ing to Wagner, upon a fat which is accumulated in drops, and
perhaps also in cells.

Consistence. — The consistence of fat is different in different
animals, and also varies in accordance with the temperature ;
thus the fat of the pig is softer than that of the ox or sheep ;
that of the human subject is intermediate between both in its
consistence, and all kinds of fat are harder in cold than in
warm weather. The variation in the solidity of fats depends
upon the amount of stearine and elaine which they contain ;
the hard fats containing a greater quantity of stearine than
the soft fats, in which the elaine is greatest.

Structure. — Most observers agree in assigning to each fat
vesicle a distinct investing membrane, notwithstanding
which fact the proofs adduced by them of the existence of such
a structure are by no means so decisive as to render such a
conclusion anything more than doubtful : thus micrographers,
hitherto have been unable to demonstrate the presence
around normal fat vesicles of an enveloping tunic, but have
been contented to rest their opinion upon the indirect and
uncertain evidence to be derived from a knowledge of the
action of re-agents ; upon testimony, in fact, analogous to
that upon which Henle and Mandl decided in favour of the
existence of a membrane surrounding the milk globule.

Schwann, indeed, states that he found the membrane of
the fat cell to be almost as thick as the blood globule of man
in an infant affected with mollities ossium.*

Henle also has observed around the obscure periphery of
a fat cell a strait and clear band, but could not assure him-
self that this was not the result of an optical illusion.f

The above are the only trustworthy observations of a
direct character recorded in proof of the existence of a dis-
tinct tunic to the fat vesicle, and they are evidently not of a
satisfactory or decisive nature.

The indirect testimony procured from a knowledge of the
action of re-agents is as follows : — Ether is stated to render

* Mikroskopische Untersuchungen, p. 140.
t Anat. Gen. p. 422.

FAT. 225

the contents of the fat vesicle fluid and transparent, without,
at the same time, diminishing its size, as is proved by the
fact that on the re -solidification of its contents, the vesicle
presents the same form and dimensions as at first.

Again, acetic acid, according to Henle, acts upon the fat-
vesicle as upon the milk globule, destroying the membrane
in different places : it permits the escape of a number of
globules of oil or grease, which, like pearl-drops, remain at-
tached to the larger vesicle.

Ether, however, produces other effects than those usually
described, and which are mentioned above ; thus, when ap-
plied to the fat vesicles of the pig, many of them will be seen
to burst, and to collapse frequently to less than the fourth
of their original size, losing, at the same time, all definite
form, and, in proportion as the vesicle collapses, one large
circular drop, or two or three smaller ones, will be seen gra-
dually to form around and envelope the shrunken vesicle,
which is, however, never entirely dissolved.

There are other observers again, as Schwann. and Henle,
who consider that fat vesicles are not merely provided with an
envelope, but that they are true cells possessing both cell
wall and nucleus.

Thus Schwann noticed in the wall of the fat vesicles of
the child already referred to a nucleus of round or oval form,
sometimes flattened, and sometimes not so.

Furthermore Henle writes, " very frequently the wall
presents a salient point on some part of its extent, and in
that position exists a nucleus, or a trace of a nucleus. Some-
times there are two nuclei, and in very many cases they can-
not be observed at all."*

Again, Mandl has made the observation in examining the
fat tissue of young rabbits, and especially in taking the little
masses of fat which lie along the vertebral column in the
interior of the pectoral cavity, that the vesicles appear but
half filled, and that they consist of two parts, an inner one
conveying the aspect of a drop of oil, and an outer mem-
branous portion, f

* Anat. Gen. p. 422. f Anatomic Microscopique, p. 141.

T 2

226

THE SOLIDS.

Such are the facts hitherto recorded in favour of the pre-
sence of a nucleus in the fat vesicle : it will be seen that
although they are more definite and satisfactory than those
adduced in proof of the existence of an investing membrane,
yet that they are scarcely in themselves sufficient to set at
rest the question of its cellular nature.

The observations then cited above, while they fail to de-
monstrate sufficiently the true organisation of the fat vesicle,
yet render it extremely probable that it is really cellular.
In favour of this view, a few additional observations have
occurred to myself, which are conclusive on one of the two
debated points of the organisation of the fat vesicle. The first
have reference to the outer membrane. If a thin slice of any
of the softer fats placed between two plates of glass be
pressed firmly, though not with too great violence, and sub-
sequently be examined with the microscope, it will be seen
that the vesicles have not run into each other, but still pre-
serve their individuality.

Again, ether applied to the fat vesicle does not entirely
dissolve it ; even when it causes it to burst and collapse, a re-
sidue always remains, and this probably is membranous.

Furthermore, if a thin slice of fat be placed between two
plates of glass, and having been forcibly compressed, be exa-
mined with the microscope, it will be seen that some of the
vesicles have burst, discharging a portion of their contents,
the membrane of the fat vesicle then becoming visible, and
declaring its existence by certain folds and markings, into
which it falls on the escape of its contents, and by the jagged
outline of the rent through which those contents passed.
(See Plate XIX. fig. 2.)

Finally, decomposition produces an effect somewhat ana-
logous to that occasioned by pressure ; the fat vesicles burst,
and their fluid contents escape, leaving the membrane in
most cases entirely empty, and which, as well as the aperture
in its parietes, may be easily detected with the microscope ;
the soft contents of- the vesicles break up and resolve them-
selves into globules of an oil-like appearance. (See Plate
XIX. fig. 4.)

FAT. 227

The second set of observations relate to the nucleus.

If a thin slice of the fat of the pig be pressed as before
between two slips of glass with a moderate degree of pres-
sure, and then be submitted to the microscope, in very many
of the cells will be seen a dark nucleus-like body. This
experiment will not, however, always succeed. (See Plate
XIX. fig. 1.)

A body of a similar description, but of a more defined
form, is very frequently encountered in the decomposing
cells of marrow fat ; this nucleated condition of the cells
preceding their rupture. (See Plate XIX. fig. 3.)

Again, in some fat cells contained in a small encysted
tumour removed from over the nasal bones, and kindly sent
to me for examination by W. H. Ransom, Esq., of Univer-
sity College Hospital, (to whose zeal and intelligence I am
indebted for many interesting specimens of morbid structure,)
nucleoid bodies were distinctly visible even without pres-
sure, although they became more apparent after a gentle
degree of compression had been applied. (See Plate XIX.
fig. 6.) The apparent nuclei in the cases related differed from
each other somewhat, being more defined and darker in the
two latter than in the former ; the cells themselves too were
not identical in appearance ; thus the margins of those of the
pig and of the human marrow fat were smooth and distinctly
defined, while those from the tumour were less regular and
distinct. (See Plate XIX. figs. 1. 3. 6.)

Now these nucleus-like bodies in the several cases men-
tioned, although occupying the position of nuclei and pre-
senting the appearance of such, it is very possible were not
in reality true nuclei ; it seems to me that their formation
might be accounted for without any reference to a nucleus.
Thus with respect to the nucleoid bodies in the cells of the
pig produced by pressure, their formation might be ex-
plained as follows : the mutual compression of the fat vesi-
cles upon each other would tend to occasion a condensation
of the semi-fluid contents in the centre of each, and in this
way the appearance of nuclei would be produced.

Again, the semblance of a nucleus in the decomposing

228 THE SOLIDS.

cells might be supposed to depend upon the partial escape by
endosmosis of the contents of those cells, the portion remain-
ing in them representing a nucleus merely from the position
occupied by it in the centre of the cells.

The formation of the nucleated bodies in the third case
would seem to point to and to require a different explana-
tion. Decomposing fat frequently exhibits a crystalline ar-
rangement : now it is conceived that the outer part of each
vesicle had become softened and broken down in consequence
of commencing decomposition or of disease preparatory to its
assuming the crystalline form, the central part at the same
time remaining unaffected.

It will be seen that the preceding observations, in relation
to the presence of a nucleus in fat vesicles, are not decisive,
although they add weight to those of anterior observers, and
render it still more probable that they are really nucleated
cells.

The facts adduced, however, in reference to the existence
of an investing membrane are quite conclusive.

On the vesicles of decomposing human fat, it is a common
occurrence to meet with stelliform figures, each being com-
posed of a number of delicate strite radiating from a central
point. On the smaller vesicles but a single figure of this
description will usually be met with, but on the larger there
may be three or four. When but one is present, it usually
covers about a third of the surface of each vesicle. (See
Plate XIX. fig. 5.)

Henle * observes of these that they might be metamor-
phoses of the nuclei of the cells ; " nevertheless," he says,
" they have more analogy with crystalline deposits."

The occurrence of two, three, or four of these on the same
cell is opposed to the idea of their connexion with the
nuclei ; and the observation of Mandl, who noticed their
formation on butter, is conclusive on this point, f

Vogel J, as also Gerber §, regard the figures in question as
groups of crystals of margaric acid.

* Loc. cit. p. 423. f Anat. Mic. f. 143.

J Anleitung zum Gebrauche des Mickroskops, p. 289. tab. 111. fig. 2.

§ Gerber's General Anatomy, translated by Gulliver.

FAT. 2'29

Distribution. — The fat vesicles are distributed in groups,
which lie near to and follow the course of the blood-vessels.
(See Plate XVIII.,/?^. 1.) This arrangement is particularly
evident in the mesentery and omentum, and may be com-
pared to that of a bunch of grapes, the fat vesicles represent-
ing the grapes, and the vessels the stalks of the bunch : in
one particular only does the comparison fail ; thus each
grape of the bunch receives and is attached to a separate
pedicle, which is not the case with the fat vesicles, although
one observer has asserted that a separate vessel is distributed
to each vesicle. The groups of fat vesicles occurring in
young animals, in which each globule is circular, may be
compared to heaps of shot piled up upon each other.

In those situations in which the fat occurs in thick and
dense masses, the arrangement referred to is somewhat dif-
ferent. The fat vesicles are still parcelled out into groups
by means of intersecting cellular bands; but the several
groups lie in close contiguity, instead of being, as in the
former case, separated from each other by distinct intervals.
Throughout these masses, too, but few blood-vessels are dis-
tributed.

The intimate arrangement of the fat vesicles having been
thus briefly sketched, it remains to describe the general dis-
tribution of fat throughout the body.

In man, fat is developed principally in the loose cellular
tissue ; it is encountered forming a layer of variable thick-
ness in that which is situated immediately beneath the skin ;
in the serous membranes, as in the omenta, the mesenteries,
and the epiploa ; on the surface of the heart, and around the
kidney.

In certain situations the subcutaneous fatty layer expe-
riences an increased development designed to fulfil certain
peculiar intentions ; thus, in the soles of the feet, the palms
of the hands, in the female breast, in the region of the pubis,
and over th« glutei muscles, especially over those of the
Hottentot women, fat is developed usually in considerable
quantities,

u

230 THE SOLIDS.

This superficial layer of fat is also generally thicker in
children and in women than in men.

Again, there are other peculiar situations in which fat
is almost invariably encountered, as in the orbit, in the arti-
culations, where it constitutes the glands of Havers, in the
shafts of the long bones forming the marrow, in the vertebral
canal, and in many other localities where vacancies occur
which require to be filled up. The marrow differs only from
ordinary fat in that the cells composing it are more circular,
with but little admixture of cellular tissue.

On the other hand, there are situations in which, under
no circumstances, is fat developed, as in the eyelids, in the
axillae, between overlapping muscles, and in the genital
organs.

Quantity. — The amount of fat varies greatly in different
species of mammalia, in different individuals of the same
species, and in the same animal at different times.

Thus certain animals seem to have a peculiar aptitude for
the formation of fat, as the pig.

Again, the various members of one family are sometimes
observed to be remarkable for the constitutional predisposi-
tion exhibited to the formation of fat. Again, other families
are met with equally remarkable for their indisposition to
fatten.

Lastly, in some animals the fat accumulates at particular
periods in greatly increased quantities, as in the hibernating
mammalia, and in the larval of insects. In man the fat
usually undergoes an augmentation after the meridian of life
has been passed.

Castration peculiarly predisposes the system to the form-
ation of fat.

Occasionally, also, fat is secreted in vast and abnormal
quantities : where this augmentation is general it constitutes
the diseased condition of obesity ; and where it is only partial
it gives rise to tumours, often of great magnitude.

In general, a certain degree of fatness argues a healthy and
vigorous condition of the system, while its excess or inor-
dinate accumulation denotes either a degree of weakness of

FAT. 231

constitution or a peculiar and unexplained state of the
system.

Disappearance. — Of all the solids in the body, fat is
developed and destroyed with the greatest rapidity : in ill-
ness, it disappears with surprising quickness, and is formed
again, under the influence of recovery with almost equal
celerity.

The exact changes which occur during the disappearance
of fat are unknown ; whatever they may be, they doubtless
affect each individual fat vesicle throughout the body, and
their nature being ascertained in a single cell would serve to
explain the disappearance of fat over the entire body. It is
uncertain whether the contents of the vesicle disappear, the
membrane remaining, or whether both are effaced together.
Beclard says that the fat vesicles themselves disappear.*
Hunter, on the contrary, assures us that they may be dis-
tinguished even when they are empty. | Gurlt states that
they contain serosity in place of grease in lean animals. J

The immediate cause of the disappearance of fat most
probably depends upon interrupted nutrition; the contents of
the cells escaping through their walls become absorbed by
the lymphatics, and thus removed into the circulation. This
view is supported by the observation of Henle, who states
that, after repeated losses of blood, the quantity of grease
in the blood augments considerably, on the surface of which
it is often seen swimming as a cream or pellicle.

Uses. — • The uses of fat are manifold and important.

1st. It serves to impart softness to the texture of the skin.

2nd. It adds grace and symmetry to the outlines of the
body.

3rd. In certain situations, as in the soles of the feet, in
the palms of the hands, and over the glutei muscles, it serves
as a, protection against the effects of pressure.

* Anatomic Generale, p. 163.

f Remarks on the Cellular Membrane in Med. Obs. and Inq., vol. ii.f
London, 1757.

j Physiologic, p. 20.

u 2

232 THE SOLIDS.

4th. Being a bad conductor of caloric, it prevents the
too rapid dissipation of the heat generated in the system.

5th. It is to be regarded as a reserve store of nourish-
ment set apart by the system during the period of its health
and strength, and designed to meet certain exigencies, when
the inherent powers of the constitution are called into re-
quisition, as in times of hunger and sickness.

Distinctive Characters of Oil Globules. — The contents
of fat vesicles are, as already stated, of an oleaginous
nature, which when they escape from the vesicles assume
the form of oil drops ; these are often met with in the
various fluids and solids of the system apart from the fat
vesicles, from which it is necessary that they should be
discriminated. There are several characters by which oil
globules may be distinguished from true fat vesicles ; thus
they are of a fluid nature, are usually perfectly spherical,
and on account of their fluidity, in place of being globular
are generally flat; they are seen sometimes to alter their
shape, as when they roll over on the surface of the object-
glass or come in contact with obstacles ; they reflect the light
less powerfully, and lastly, the slightest degree of pressure
causes them to coalesce.

There is but little probability of confounding oil globules
with air bubbles ; these have a different colour, reflect the
light differently, and are perfectly globular.

EPITHELIUM. 233

ART. IX. EPITHELIUM.

As the external surface of the body is invested with a cuticle
which has received the name of Epidermis, so are its internal
free surfaces in like manner clothed with a delicate pellicle
which has been denominated Epithelium.

Both the epidermis and epithelium are constituted of
cells : there is this difference, however, between them, that
while the former, by the intimate union and superimposition
of its cells, exists as a distinct and continuous membrane,
the latter, owing to the feeble cohesion of its constituent
cells, can scarcely, except in certain situations, be shown to
exist as a united and extended structure.*

The epidermis and epithelium are therefore hardly to be
regarded as distinct structures, but rather as the same, the
differences observed between them being merely modifications,
the result of the different circumstances to which they are
each subject.

The essential identity of the two may be shown by an ex-
amination of the epidermis at the outlets and inlets of the
body, where, by gradual transition, it may be traced inwards
into the condition of epithelium ; and this also, traced from
within outwards, will be observed gradually to acquire the
characters of epidermis ; so that, within a certain distance
of the termination of the cavities of the body, which open
externally, the epithelium may also be demonstrated as a
distinct membrane ; this membrane may be followed in man
from the lips as far backwards as the posterior part of the

* Leeuwenhoek first discovered in the mucus of the vagina little scales,
which he presumed formed the internal membrane of that canal, and from
which he conceived they become detached by coitus,. (Opera, t. i. p. 153.
155.) He likewise noticed that the mucus of the mouth contained scales,
(Ibid. t. iii. p. 51.), and he saw also the cylindrical epithelial cells of the
intestinal cavity. (Ibid. p. 54. 61.)

u 3

234 THE SOLIDS.

mouth, also passing over the tongue ; and in the horse and
in birds it may be shown to exist in the stomach and gizzard.

The epithelium will be first described, inasmuch as its
organization would appear to be more simple than that of the
epidermis, which, by modifications of its cells, is converted
into so many apparently distinct structures.

It has been remarked that the internal free surfaces of the
body are covered by epitheliuni : these surfaces comprise those
of both the open and the closed cavities, the former of which
include the alimentary canal from mouth to anus, the genito-
urinary organs and passages of both the male and female, and
the respiratory track, consisting of the trachea, bronchi, cells of
the lungs and nares ; the latter consist of the great serous
sacs of the head, chest, and abdomen, and the lesser ones
of the pericardium, tunica vaginalis, the cavities of the joints,
and of the lymphatic and blood vessels, including the heart.

The bursar are said by Henle * not to be furnished with
an investing epithelium, — a statement to be received with
some degree of hesitation.

It would appear, therefore, that, with the single doubtful
exception alluded to, every free surface of the body is in-
vested with its own appropriate epithelium, the ventricles of
the brain even being lined with an epithelium proper to
them, and the surface of the cornea being covered with one
also. The existence of an epithelium in this latter situation
may be directly proved by means of the microscope ; and it
may be inferred from the observation of the fact, that in
the general casting of the epiderm of snakes and other reptiles,
a delicate film is likewise thrown off from the surface of the
cornea.

The epithelium has not the same character in the different
situations in which it is encountered, but the cells of which
it is composed differ in form and size, according to age and
the locality occupied by it.

The several varieties of epithelium may be reduced into
two principal types, in the first of which the cells are more or
less circular or polygonal, and in the second are elongated and

* Anat, Gen. vol. vi. p. 225.

EPITHELIUM. 235

conoid. These two forms may be distinguished by the appel-
lations of Tesselated or Pavement Epithelium, and Cylindrical
or Conoidal Epithelium. (See Plate XX. fig. 1. and 2.)

The Conoidal Epithelium admits of subdivision into Naked
Conoidal Epithelium and Ciliated Conoidal Epithelium.

TESSELATED EPITHELIUM.

Form. — The cells of this description of epithelium form many
layers, are flattened, and either circular, polygonal, or irregular
in outline : the younger cells are mostly of the first shape, and
are thicker than the older ones, which are irregular in form,
thin and membranaceous, while the polygonal cells are en-
countered more particularly in certain situations, as on the
choroid plexus, pericardium, and serous membranes in general.
The polygonal shape is produced by the mutual compression
exerted by the cells upon each other, and consequent adapta-
tion.

Size. — The size of the cells of pavement epithelium varies
both according to age and locality ; the younger and deeper
seated cells are of course smaller than the older and more
superficial ones ; the larger cells are met with in those situa-
tions where the epithelium is continuous with the epidermis.,
as in the mouth and oesophagus, the vagina, urethra, and
bladder, the commencement of the rectum, the inferior di-
vision of the nares, lining the eyelids, and covering the
cornea. (See Plate XX. Jig, 1.) On the contrary, the
epithelium of the pericardium, ventricles, aorta, and of most
of the closed cavities is composed of cells which are very
much smaller in size than those of the localities previously
enumerated. (See Plate XXII.)

Structure. — Epithelial cells illustrate faithfully the doc-
trine of cell development, each consisting of a nucleus, cell
wall, and intervening space enclosing fluid, both the nucleus
and the cell wall exhibiting a granular composition.

It has been observed, that the younger cells are thicker
than the older and fully developed ones, which become re-
duced to mere membranous expansions, from which it fol-

u 4

236 THE SOLIDS.

lows that the space intervening between the nucleus and
cell wall is greatest in the younger cells, while it is almost
obliterated in the older. The smaller cells are also more
granular than the larger : now these two facts stand in close
relationship with the function discharged by these cells,
and which is so much the more active as the cavity is large
and the granules numerous.

The nucleus is likewise best seen in the younger cells : in
the older ones it becomes either entirely obliterated, or it
escapes from the cavity of the cell, the position which it
previously occupied in it being indicated by a depression ; it is
for the most part circular ; but occasionally, and particularly
in certain localities, it is found to be oval, as in the epithelium
of the lower two -thirds of the uterus, in that of the peri-
cardium, and also in that of the blood vessels, the aorta
excepted: it sometimes occupies a central position in each
cell : at others it is excentric.

The properties of pavement epithelial cells, as well as their
form, size and granular texture, alter also with age: thus
the younger cells are dissolved, with the exception of the
nucleus, by acetic acid, whilst the same re-agent applied to
the older ones produces scarcely any appreciable effect.

Epithelial cells, on the addition of water, or after death,
become white and opaque — a common effect of water on all
animal structures. The change in the case of the epithelial
cells probably depends upon the coagulation of their fluid
contents ; and to it the characteristic dulness of the eye after
death is due.

Distribution. — This form of epithelium is more exten-
sively distributed than the conoidal variety: it is encoun-
tered on the free and serous surfaces of all the closed cavities,
as of the cranium, thorax and pericardium, abdomen and
tunica vaginalis, lining the lymphatic and blood vessels, even
the ventricles of the brain itself, in which it rests immedi-
ately upon the cerebral substance are not free from it : it is
met with likewise near the terminations of those cavities
which open externally, as in the mouth, where it extends as
far backwards as the cardiac extremity of the stomach, in the

EPITHELIUM. 237

lower portions of the nares, whence it passes into the frontal
sinuses, in the vagina and uterus, the lower two-thirds of
which it lines, as also the urethra. In the male subject
it passes over the glans penis, and then enters the urethra.

The epithelium of the urinary apparatus should perhaps
be referred to the pavement epithelium : its cells however
vary very considerably in form : thus many of them de-
cidedly resemble the variety of epithelium under discussion ;
others, however, are clavate, the narrow or fixed extremity
being often produced into a long thread or filament; and
again, others imperfectly represent the conoidal variety of
epithelium : these last, as well as the clavate cells, are met
with in the greatest quantity in the upper part of the
bladder, and in the ureters.

CONOIDAL EPITHELIUM.

Form and Size. — The cells of this form of epithelium are
much more regular in size and shape than those of the tes-
selated or pavement kind : the term cylindrical usually applied
to them is, however, far from accurate, since they do not pos-
sess, even in a slight degree, the outward form of a cylinder :
the word conoidal, here used, serves to express much more
closely the real form of the cells of this variety of epithe-
lium, although it fails to give an exact idea of their shape :
thus the cells in question are not merely conical with flat
summits, but each cone is flattened at the sides, so that
when the bases of the cones are seen directly, they exhibit
the appearances of ordinary polygonal tesselated epithe-
lium ; the side view of the cells will at once make manifest
their distinctness. (See Plate XX. fig. 2.)

Conoidal epithelial cells are usually disposed more or less
vertipally to the surface upon which they rest, their narrow
extremities being turned downwards, and attached to that
surface, and the broader and free "ends being directed
upwards.

Structure. — The cells of conoidal epithelium have pre-
cisely the same structure as those of the previously de-

238 THE SOLIDS.

scribed kind; that is, they consist of nucleus, cell wall,
granules, and fluid contents: the chief difference is one of
form and not of structure.

The nucleus is almost invariably oval, the long axis corre-
sponding with that of the cell itself : it is often so large as to
occasion the cell to assume a ventricose form, it being con-
tracted immediately above and below the part in which the
nucleus is situated. Some observers speak of two nuclei in
a single cell : this, however, must be an exceedingly rare
occurrence, as I have never yet met with a single example
of the kind.

The conoidal epithelium is, as already remarked, divisible
into two kinds.

Naked Conoidal Epithelium.

Distribution. — This subdivision of epithelium, to which
the description just given more immediately applies, is met
with investing the mucous membrane of the alimentary
canal, extending from the cardiac extremity of the stomach
to within two or three inches of the rectum ; it is encoun-
tered likewise lining the several ducts and prolongations
which communicate with this : thus this form of epithelium
exists in the gall-bladder, where it is of a deep yellow colour,
in the ductus communis choledocus, in the pancreatic duct,
and in the mucous crypts or follicles imbedded in the
mucous membrane. It is found also in the upper portion of
the nares, in the salivary ducts, in the appendix vermiformis,
and in a modified form in the vas deferens.

In the stomach, the naked conoidal epithelium does not
exist in an unmixed form ; it occurs intermixed with pave-
ment epithelial cells, probably derived from the oesophagus,
and carried down during deglutition.

It is in the gall-bladder, the small intestines and the ap-
pendix vermiformis, that the naked conoidal epithelium exists
in the greatest perfection.

EPITHELIUM. 239

Ciliated Conoidal Epithelium.

The cells of this variety of conoidal epithelium agree pre-
cisely in form, size, and arrangement with those of the first
described subdivision, the only difference being, that they are
possessed of the singular addition of vibratile cilise.* (See
Plate XXI. fig. 3.)

The ciliae taper from base to apex, are attached to the
thickened margins of the summits of the cells, ten or twelve
of them belonging to each. In the frog they would appear
to be not merely attached to a circular line, but also to the
segment of the cell described within this. (See Plate XXI.

fig- i.)

During life the ciliae are in a constant state of activity : the
power by which their motions are effected is, however, in-
volved in the greatest obscurity : it can scarcely be the re-
sult of muscular structure, as some have supposed, since the
entire cilia is many times smaller than the smallest mus-
cular fibre. The idea has been put forth that the ciliaa are
hollow ; that they communicate with a vessel which runs
along their bases, containing fluid ; and that they are moved
by the successive injection and expulsion of this fluid.

One fact has been observed, which affords countenance to
the above explanation of the motion of the cilias, viz., that
this takes place in a determined direction : commencing in the
cilia? on one side, it runs along them to the opposite, the
several cilia? being thus successively called into action. It is
this peculiar character of the motion of the cilia? which has
led to its comparison with the waving of a corn-field over
which the wind passes in successive gusts. The motion, in
whatever way effected, is singularly beautiful, and, strange to
say, exhibits many of the characters of volition : thus it will
f

* To Purkinje and Valentin especially belong the honour of making
known in all its extent the phenomenon of ciliary motion, and which
before that time had been. observed only in some few of the lower animals,
and concerning the nature of which many errors prevailed. They dis-
covered it in the respiratory arid female genital organs in 1834. (Midler,
Archiv. 1834, p. 391.)

240 THE SOLIDS.

sometimes cease altogether for a time, and then suddenly
commence again. It is also sufficiently powerful to effect
the entire displacement of the cell or corpuscle to whicli
the ciliae are attached, and many of which may frequently
be seen moving freely and quickly about, usually in circles,
in the field of the microscope. This curious spectacle is
most readily witnessed in the ciliary cells of the trachea
of the frog, which are of a different form from those of the
mammalia, being rounded in place of elongated and conoid al.
(See Plate XXL fig. 1.)

The combined motion of the ciliae is also capable of
putting in movement either fluids or solid particles which
may come into contact with them. This fact those who
are given to microscopic investigation will have had many
opportunities of verifying, and one may easily at any time
acquire the proof of it by mixing with the fluid in which
the ciliae are acting some fine powder, as, for example, of
carbon.

The motion of the ciliae, when acting in combination, is
stated to take place always in a determined direction from
within outwards. It would appear, however, from the ob-
servations of Purkinje and Valentin * that the direction is
capable of reversion : thus, these observers saw the accessory
branchiae of the anodon vibrate during from six to seven
minutes in one direction, and afterwards, during the same
lapse of time, in an opposite.

The influence of physical and chemical reagents upon the
vibratile movement has been carefully examined. Thus, if
a portion of vibratile epithelium be touched or scraped, the
motions of the ciliae will become more active, and sometimes
commence again even after they had become extinct. They
cease at a temperature below the freezing point, and at a
degree of heat sufficient to occasion the coagulation of the
animal fluids. Galvanism destroys their action, but in a
local manner, — a fact which a reference to the constitution
of epithelium by the union of separate cells may serve to
explain. Amongst chemical reagents, narcotics are without

* Motus Vibrat, p, 67.

EPITHELIUM. 241

influence ; acetic and the mineral acids destroy the motion, as
also caustic ammonia, nitrates of potash and of silver. The
serum of the blood prolongs its duration. Urine and white of
egg are without effect upon it. Bile instantly destroys the
activity of the ciliae.

The ciliary motion soon ceases after death in the mammalia,
but continues in many of the invertebrata, and especially in
several of the mollusca, as for example, in the river muscle
and the oyster, for days after the death of the animal.

It would appear, therefore, that each ciliated corpuscle
bears the closest possible resemblance to many of the infusory
animalcules, and it is questionable whether its claim to be
regarded as a distinct entity be not equally strong.

Distribution. — Ciliated epithelium has not been as yet dis-
covered amongst the mammalia in any closed cavity, but
always in situations which communicate with the air ; thus
it is met with, as is generally known, lining the trachea and
bronchi, extending even to their minutest ramifications ; again,
it is encountered in the fallopian tubes, and lining the upper
third of the cavity of the uterus of adult animals, but not
that of young mammalia. There is yet another locality in
which I believe it also to exist, viz. in the convolutions of
the tubuli seminiferi of the epididymis.

On the other hand, there are many situations in which it
has been repeatedly asserted to exist, but in which patient
and repeated investigation has failed to reveal its presence, as
for example, in the ventricles of the brain *, covering the pia
mater, and lining the eyelids and frontal sinuses, f

The epithelium of these several parts, on the contrary, is
pavement and not ciliated epithelium. (See Plate XXIV.)

Purkinje }, in describing the epithelium of the ventricles,
does so most circumstantially, and states that he followed the
vibratile movement in the sheep from the lateral ventricles
through the third ventricle, and by the aqueduct of Sylvius
into the fourth.

* Purkinje in Muller, Archiv. 1836, p. 289.

f Henle, Anat. Gen. t. vi. p. 252. { Muller, Archiv. 1836.

242 THE SOLIDS.

Valentin * confirms the accuracy of this description as
regards man.

We find Henle f describing the epithelium of the ventricles
as a cuneiform ciliated epithelium ; and in Gerber's General
Anatomy, we remark that it is stated to be a tesselated
ciliated epithelium. It is singular how so great an error
could have originated, and still more so how it could have
been so long perpetuated.

DEVELOPMENT AND MULTIPLICATION OF EPITHELIUM.

Each epithelial cell is first detected as a nucleus without
any appearance of cell wall around it: this however may
exist closely embracing the nucleus, even from the earliest
period at which this can be observed. After a time, how-
ever, a transparent border becomes visible, surrounding
the nucleus : the width of this goes on gradually increasing
until at length the full dimensions of the cell have been
attained : now the outer limit of this border doubtless indi-
cates the cell wall, the clear space between it and the nucleus
being in the younger epithelial cells filled with fluid. In
the conical epithelium the cell wall is not developed equally
around the nucleus as in the pavement epithelium, but
chiefly in two opposite directions.

It has been observed, that young epithelial cells are
thicker and rounder than the older ones ; it has also been
remarked, that they are more granular ; facts which stand in
close relation with their functional activity.

It has been noticed likewise, that the nucleus in the pro-
gress of development becomes either obliterated, or that it
escapes from the cell. Now it has struck me that this dis-
appearance of the granular nucleus and granules of the cell
wall might possibly be connected with the reproduction
or multiplication of epithelial cells, as well as of cells occur-
ring elsewhere than in the epithelium, and that each granule
might in reality be an epithelial cell in embryo. This is

* Repertorium, 1831, p. 158. 278. f Anat. Gen. t. vi. p. 253.

EPITHELIUM. 243

of course but a conjecture : it is one, however, which would
appear not to be contradicted by any other known fact, and
to have analogy in its favour ; the mode of reproduction
amongst the lower algae being precisely similar.

The occurrence of two nuclei in the same cell has been
recorded by some observers, and who have from this fact
drawn the inference, that epithelial cells are multiplied by
division. This method of increase cannot, however, be pre-
sumed to prevail to any extent, since it is a circumstance of
extreme rarity to meet with two nuclei in the same cell.

NUTRITION OF EPITHELIUM.

The epithelium has no immediate or structural connexion
with the parts which lie immediately beneath it, neither
does it receive blood-vessels and nerves from those parts ; it
is simply dependant upon them for the supply of nourish-
ment, of which it is the recipient, and which is derived from
the blood-vessels distributed throughout the tissue of the
true skin lying beneath it, and from which vessels the plasma
is continually escaping by transudation or exosmosis.

DESTRUCTION AND RENEWAL OF EPITHELIUM.

The epithelium in every part of the body is continually
undergoing a process of destruction, and consequent re-
newal.

It is less easy to establish the fact of the destruction of
the epithelium in the closed cavities than in the open ; never-
theless, that it really does take place even in these, may be
inferred from the observation of the fact that the cells of
epithelium encountered in such localities represent every
degree of development, many of the older ones also being
destitute of nuclei, and more or less broken, into fragments.
It is probable, however, that the process of destruction is
slower in the closed than in the open cavities.

244 THE SOLIDS.

In the open cavities, the destruction of epithelium is doubt-
less more considerable and more rapid ; it is also more easy
to determine in these : thus during mastication, deglutition,
and digestion, a considerable amount of epithelium becomes
disturbed, removed from the surface to which it was at-
tached, and mixed up with the saliva, mucus, gastric fluid,
food, &c., and finally is discharged from the system with the
fceces, in which by microscopic examination it may readily be
detected.

The fact of the gradual and continual destruction of epi-
thelium may likewise be ascertained by an examination of
the several fluids discharged from the system, as the saliva,
the mucus, from either mouth, nose, lungs, urine, seminal or
menstrual fluids, in all of which the microscope will reveal
an abundance of epithelial cells.

The same fact may also be determined by a microscopic
examination of the scum which collects during the night on
the lips and around the base of the teeth of many persons.

In certain situations the epithelium undergoes not merely a
gradual, but also a periodical destruction, as in the uterus at
the monthly periods and after parturition.

The continual destruction of epithelium having been thus
rendered manifest, its renewal follows 'as a matter of ne-
cessity.

In irritation of the mucous membrane of the bronchi, nose,
and alimentary canal, it is possible that the epithelium, during
the period of the continuance of the irritation, is entirely
destroyed.

USES OF EPITHELIUM.

The first use of the epithelium is a passive one, it serving
like the epidermis as a protection to the more delicate parts
which lie immediately beneath it.

The second use is active, the epithelium doubtless being
an important agent in secretion.

Each epithelial cell may be regarded as a gland reduced to
its most simple type or condition, it embodying all that, i<*

EPITHELIUM. 245

essential in the largest and most complex secreting organ,
viz. the true secreting structure.

The nature of the fluid secreted by epithelial cells is not
everywhere identical, but varies according to their exact
structure and the locality in which they are found : thus in
some situations they secrete serum, as in the serous sacs ;
in others mucus, as in the mouth, nose, alimentary canal, &c. ;
in others synovia, as in the joints ; in the stomach and in the
duodenum, they assist in the elaboration of the fluids which
are there found.

That the epithelial cells are the real agents engaged in the
production of the several fluids named, is rendered certain
by the facts that they correspond precisely with the un-
doubted secreting structure of true glands ; and further, that
in the situations where they are found, no other organisation
exists to which the function of secretion could with any de-
gree of probability be assigned.

The importance of the office discharged by the epithelium
explains, then, the universality of its distribution.

The diffusion of epithelial or secreting cells over the sur-
face of membranes which require to be kept continually mois-
tened by a suitable fluid, affords a beautiful example of the
wise adaptation of means to an end : by no other means than
that employed could the end in view be so surely accom-
plished or with so great an economy of space.

The above described uses of epithelium are common to it
wherever encountered : the third use is mechanical, and ac-
complished only by the ciliated form of epithelium.

It has already been observed that the force of the combined
action of the cilia3 is so great as to enable them to carry
along with or drive before them fluids, and even solid par-
ticles which may happen to come in contact with them : it
has likewise been remarked that the direction of their united
action is invariably from within, outwards or towards the
outlets of the body ; at least it is so amongst the mammalia.
From a knowledge of these facts it is not difficult to suggest
the probable use of vibratile epithelium in the localities in

x

246 THE SOLIDS.

which it has hitherto been discovered in man and the mam-
malia.

Thus in the bronchi and trachea, it may be presumed to
be designed to facilitate the escape from those passages of
any foreign particles which may have found entrance to
them.

Again, in the fallopian tubes and upper portion of the uterus,
it can scarcely be questioned, but that its use is to hasten the
progress of the ovum from the ovary to the uterus ; and, pre-
suming that the direction of the action of the cilia may be,
and is sometimes reversed, the vibratile epithelium of these
parts may be further intended to insure the more speedy
transmission of the seminal fluid along the fallopian tubes to
the ovary, upon which it has been detected by more than one
observer.

EPIDERMIS. 247

ART. X. EPIDERMIS.

THE entire of the external surface of the body is invested
with a membrane which has been denominated epidermis,
formed of superimposed layers of nucleated cells (see Plate
XXIV.jtfy. 3.), and the number of which layers is greatest
in those situations in which the membrane is subject to the
most pressure, as in the palms of the hands and soles of the
feet, in which the epidermis sometimes attains the thickness
of the j1^ or even the ^ of an inch.*

The form, structure, and development of the cells com-
posing the epidermis are in every respect identical with those
of the tesselated variety of epithelium already described ;
thus, first, the younger and deeper-seated cells are spherical
in outline, and almost globular, while the older and more
superficial cells become irregular in form, expanded, thin,
and membranaceous ; secondly, like those of the tesselated
epithelium, the cells consist of a nucleus, cell wall, cavity,
and granules ; it is, however, worthy of remark, that the
nucleus, as well as the majority of the granules contained in
the epidermic cells, disappear at an earlier period of develop-
ment than do those of the epithelium, facts which will be
explained when the uses of the epidermis come to be treated
of; thirdly, the plan of development is the same in the two
cases, the cell wall being developed around the nucleus,
which is the part first formed.

Thus far then there is a close correspondence between the
epidermis and epithelium, so close indeed as to make it ap-
parent that the two are but modifications of one and the
same structure. The chief respects in which it differs from
the epithelium are in the compact and firm union of the cells

* Leeuwenhoek first observed that the epidermis was composed of
scales placed one against the other, and also that, after a certain lapse of
time, they were cast off and their place supplied by others.

x 2

248 THE SOLIDS.

with each other, whereby it forms a distinct and continuous
membrane, and in the paucity of granules dispersed through-
out the cells.

The epidermis also stands in precisely the same relation
with the parts beneath it as the epithelium ; thus, it has no
structural connection with those parts, and receives neither
blood-vessels nor nerves from them, but is simply dependent
upon them for the plasma which is continually escaping from
the blood-vessels of the true skin. This want of structural
connection is shown by the fact that a portion of the cuticle
may be detached without its removal occasioning either pain
or haemorrhage.

This separation of the epidermis from the dermis fre-
quently takes place during life, as from a burn, scald, or
blister, or from the effusion of serum, the result, not of in-
jury, but of disease. After death and on the commence-
ment of decomposition, the epidermis may be detached in
large masses, the prolongations sent down to the sebaceous
and sudoriferous glands also coming away with it.

The epidermis does not merely cover the whole external
surface of the body, but sends processes into its various out-
lets, as the mouth, nose, rectum, vagina, and male urethra;
these prolongations soon lose, however, the characters of epi-
dermis, and acquire those of epithelium.

The epidermis likewise sends down processes into the
sebaceous and sweat glands, and which, forming a perfect
tube, serve to convey the secretions of those glands to the
surface, on which they open as raised and rounded papilla?,
with central depressions and apertures. (See Plate XXIII.
Jigs. 1 and 2.)

A sheath of epidermis likewise encircles the base of each
hair.

The number of these infundibuliform processes and sa-
lient papilla? which open on the surface is immense, and may
be stated at about 3000 to the square inch, which, com-
puting the number of square inches of surface in a man of
average size at 2500, would give 7,500,000 for the entire
surface of the body.

EPIDERMIS. 249

In addition to the papillae, we observe on the surface of
the epidermis a great number of lines or furrows which
map it out into a network of small polygonal and lozenge-
shaped spaces ; these are of two kinds, the one large and
coarse and corresponding with the flexures of the joints ;
the others smaller, occupying the interspaces between the
larger, and also being generally distributed over the surface
of the epidermis, where the articular furrows have no ex-
istence. The plan of arrangement of the smaller lines is
as follows : — a number of straight lines, usually from six to
ten, radiate, like the rays of a wheel from its centre, from
each hair-pore ; these usually come in contact with the lines
proceeding from other hairs. These radiating lines thus
mark out the surface into triangular spaces, between which
are usually situated two or three other pores, those of the
sebaceous and sweat glands ; from each of these also similar
radiating lines proceed ; these unite with the coarser lines
given off from the hair follicle, and occasion a still further
subdivision of the surface of the epidermis into triangular
spaces. The result of this minute subdivision is to occasion
the whole surface of the epidermis to assume a minutely and
beautifully reticular appearance. The coarser lines are best
seen in the palms of the hands and soles of the feet, while
the smaller and finer lines may be readily traced, following
the disposition just described on the back of the hand.

The effect of water in rendering the cells of tesselated
epithelium white and opaque has been referred to : its long-
continued application to even the living epidermis produces a
similar result, which most persons must have observed, al-
though some would be at a loss to account for it ; thus, the
skin of the fingers of those who have been engaged in wash-
ing for some hours becomes of a pearly whiteness.

It sometimes happens that epidermic cells are developed
in increased and abnormal quantities, giving rise to tumours,
and which are by no means of uncommon occurrence.

x 3

250 THE SOLIDS.

EPIDERMIS OF THE WHITE AND COLOURED RACES.

Between the epidermis of the white and the coloured
races there is a perfect identity of structure ; the only
difference is, that the young epidermic cells of whites con-
tain little or no colouring matter, or pigment granules,
except in certain situations, while those of blacks are filled
with them; this difference can scarcely be regarded as
permanent or structural; it is one rather of degree than
kind, and over which, moreover, climate exerts an all-
powerful influence.

We have continual opportunities of witnessing the effect
of climate in increasing the amount of pigmentary matter
in the skin. All have noticed that after a few years' resi-
dence in a hot country, the skin of many individuals becomes
several shades darker than it was previously, and that even
the inhabitants of the same country are darker during the
summer than in winter.

It would appear, therefore, to be very possible, that
climate alone, operating through many ages, would be suf-
ficient to change the colour of the skin from white to all the
varying shades of red, olive, and black, met with amongst
the different families of the human race.

DESTRUCTION AND RENEWAL OF EPIDERMIS.

The epidermis, like the epithelium, is constantly under-
going destruction and renewal ; the evidences of this are,
however, more obvious and striking in the case of the epi-
dermis, than were those adduced in proof of the destruction
of the epithelium.

Thus the destruction of the epidermis is proved by a
variety of facts : —

By the gradual disappearance from the skin of indelible
stains, such as those produced by nitrate of silver or nitric
acid.

EPIDERMIS. 251

By scraping the soles of the feet after immersion in warm
water ; the white and powdery material which is obtained,
often in large quantities, examined with the microscope, will
be found to consist of epidermic scales.

By the use of the warm bath ; floating on the surface of
the water will be observed more or less of a thin and whitish
scum ; this consists of desquamated epidermis.

By rubbing the moist skin with a rough towel ; a consi-
derable amount of epidermis visible to the naked eye will be
removed.

The skin of new-born children is frequently observed to
be covered with a white and soap-like crust ; this, examined
with the microscope, will be found to consist of epidermic
scales mixed up with sebaceous matter.

The last proof to be adduced of the desquamation of the
epidermis is one derived from disease ; after inflammation of
the skin, whether that of erysipelas, scarlatina or measles,
the epidermis peels off, a new one being previously formed
beneath the old.

Amongst many of the amphibia and reptiles, the casting
of the epidermis is a periodical occurrence ; in man, on the
contrary, it is a constant and gradual process normally,
although it is also occasionally periodic from disease.

USES OF THE EPIDERMIS.

The principal uses of the epidermis are threefold.

The first and chief use is to serve as a protection to the
more delicate parts which lie immediately beneath it.

The second is to prevent the too rapid dissipation of the
caloric of the system.

The third use has reference to secretion. It is evident,
however, that the importance of the epidermis as a secre-
ting organ is not considerable, seeing that the external
surfaces of the body do not require to be kept moist, to the
same extent as the internal. That the epidermis does not

x 4

252 THE SOLIDS.

very actively administer to secretion might be inferred from
the transparency of the fully developed cells, the faintness
of the nuclei, and the paucity of the granules contained
within them.

Epidermic cells are also capable of absorption, a fact which
their change of colour after long immersion in water
testifies.

By far the best description of the anatomy of the epidermis
which has fallen under my notice is that contained in the ad-
mirable chapter on the Anatomy and Physiology of the Skin
attached to the second edition of Mr. Wilson's work on the
Diseases of the Skin.

THE NAILS. 253

ART. XL THE NAILS.

THE horny appendages of the feet and hands, the nails, do
not constitute a distinct structure or type of organisation in
themselves, but are merely modifications of one which has
already been described, viz. the epidermis.

Nails, therefore, consist of cells similar to those of which
the epidermis is itself constituted, with the difference, that
they are harder, drier, more firmly adherent to each other,
and that in the majority the nucleus is obliterated. (See
Plate XXV.)

To display the cellular constitution of nails some little
nicety is required ; it may be shown, however, in the thin
scrapings of any fragment of nail submitted to the microscope,
as also by soaking the nail in a weak alkaline solution, and
which, acting upon and dissolving the intercellular and uniting
substance, sets free the cells.

The cellular structure of nails may also be shown, even
without previous preparation, by a careful examination of the
root and under surface of the nail, in which situations young
and nucleated cells may usually be detected.

The younger nail cells, like those of the epidermis in the
coloured races, contain pigmentary matter.

Nails, however, are not simply constituted of superimposed
and adherent cells, but these are regularly disposed in layers
or strata, each of which probably indicates a period of
growth.

These layers, marked by striae, may be clearly seen on any
thin section of nail, whether longitudinal or transverse ; they
do not appear to follow any very definite course ; usually in
a longitudinal slice, they run from above downwards and for-
wards ; sometimes they are horizontal, but I have seen instances
in which the striae were directed obliquely backwards, in place
of forwards. In the transverse section,- the striae are less
strongly marked, and run usually more horizontally. (See

254 THE SOLIDS.

Plate XXV.) Occasionally they are seen to pass in opposite
directions, and to decussate. I am disposed to think that
the one set of striae visible are rather apparent than real, and
are produced by the knife employed in making the section.

It is usually easy to distinguish the superior from the
inferior edge of a slice of nail; the former will generally
appear quite smooth, while the latter will be rough and un-
even. (See Plate XXV.)

Such is a brief sketch of the structure of nails * : their form,
position, and mode of connexion may next be considered.

Each nail may be said to be quadrilateral and convex from
side to side, as it is also very generally from before back-
wards ; the three posterior margins are received into a groove
formed by a duplicature of the dermis and epidermis, the
anterior margin alone being free. The root and sides of the
nail, the former consisting of about one-fifth of its extent, are
intimately attached to both surfaces of the groove; the inferior
aspect of the body of the nail is likewise firmly adherent
to the derm beneath it, except for a small distance at its
anterior part.

The nail, then, is attached to' the dermis by its root, and
by a portion of its inferior surface ; this attachment, however,
is scarcely to be considered as structural, since it consists of a
mere adaptation of the opposing surfaces of the dermis and
nail. The surface of the dermis upon which the nail rests,
it is known, is not smooth, but is raised into papillae ; to these
the nail adapts itself, and in this way the two become inti-
mately united.

It is in this manner, also, that the longitudinal lines ob-
served on most nails are produced, and the appearance of
which has induced some observers to entertain the idea that
they are of a fibrous, and not a cellular constitution.

* The first exact description of the nail and of the disposition of the
derm which supports it was given by Albinus (Adnotat. Acad. lib. ii. 1755,
p. 56.), but Schwann showed that the nail had a lamellated structure,
and that the lamellae are composed of epidermic scales. (Mikroskopische
Untersuchungen, 1839, p. 90.)

THE NAILS. 255

Nails are, to a considerable extent, hygroscopic, becoming
by the imbibition of fluid soft and yielding.

DEVELOPMENT OF NAILS.

Nails are developed somewhat differently from the epider-
mis of which we have stated that they are a modification ;
thus they do not increase by the equal development of new
cells on the entire of their under surfaces, but they grow from
a point, from the base or root of the nail.

The reality of this mode of development becomes evident
from the following considerations : —

1st. That the younger nail cells are found principally at
the root of the nail.

2nd. That if the relative situations of two spots or stains
be observed, it will be seen that during the growth of the
nail, they preserve precisely the same relation with each
other, only that they gradually approach the end or free
margin of the nail, which at length they reach, and from
which finally they are worn away. This observation proves
the absence of interstitial growth, and shows that the nail
increases in length by additions made to the root.

Although it is certain that the longitudinal growth of nail
occurs by the development of cells at the root, yet it is also
evident that its thickness is increased by the formation of
new cells on its under surface, where they may usually be
detected with the microscope in a partially developed state.
This double development explains why the nail is thinnest at
the root, where only a single method of growth prevails.

The junction of the root with the body of the nail is in-
dicated by a semicircular line, and the former is not merely
thinner than the latter, but it is also softer and whiter;
whiter in consequence of the subjacent dermis containing
in that situation fewer blood-vessels, and its papilla being
smaller.

From the preceding account of the development of nails,
it follows that when these sustain any loss of substance on
their upper surfaces, this loss is never repaired, but remains
without alteration until it reaches the free margin of the nail

256 THE SOLIDS.

Epithelium, epidermis, nails, and some other structures of
the body, never seem to attain to a stationary state ; they are
throughout the whole of life undergoing a process of deve-
lopment; this in the case of the nails of man renders the
interference of art necessary to remove from time to time
the redundant growth.

It is probable, however, that if the nails were not cut, but
allowed to grow at will, they would not exceed a certain
length ; amongst the Chinese, who do not pare their nails,
they are usually about two inches long.

Nails doubtless sustain a loss of substance beyond that which
they experience from occasional cutting, as from friction and
the desquamation of the cells from the inferior and anterior
portion of each nail, and which may be inferred to take place
from the fact that the matter which accumulates beneath the
extremities of the nails is to a great extent made up of epi-
dermic or nail cells.

It has been estimated that the entire body of a nail, from
the root to its free margin, is developed in from two to
three months.

The third month of intra-uterine life is the earliest period
at which the nails can be detected ; they then consist of nu-
cleated cells, and rather resemble soft epidermis than the
hard and horny texture of fully developed nails.

A nail which has been once entirely destroyed is always
regenerated in a very imperfect manner, it being usually
seamy and irregular in consequence of the disturbance and
injury sustained by the subjacent dermis, and the markings
of which are impressed upon the nail.

Nails are subject to deformity in certain chronic maladies
of the heart and lungs, especially in cyanosis and phthisis.
It has been suggested that this may depend upon the state
of the circulation in the vessels of the dermis.

The various modifications of nail met with throughout the
animal kingdom, the claws of birds and carnivora, the hoofs
and horns of ruminants, have essentially a similar structure
to the nails of man. The hoof of the horse and of some
other animals is traversed from above downwards by the
spiral ducts of the sebaceous glands.

PIGMENT CELLS. 257

ART. XII. PIGMENT CELLS.

Colouring matter is found in the animal organisation in
two states, either diffused throughout the fluid contents of
colourless cells, as in fat cells generally, but especially in
those of the iris of birds, and as in the liver cells, and red
blood discs, or it is limited to the granules contained in cer-
tain peculiar cells, the parietes of which are also colourless,
which have received the name of pigment cells, and which we
are now about to describe.

Pigment cells have precisely the same structure as those
of epithelium and epidermis, the description of which has
just been brought to a conclusion ; that is, they consist of cell
wall, nucleus, cavity, and granules ; the only difference be-
tween the two is, that the granules in the one case are
coloured, and in the other colourless: as may be inferred
from their similarity of organisation, a similar mode of de-
velopment prevails in both.*

All the varieties of colour of the eye and of the skin ob-
served amongst the different members and families of the
human race depend upon the number of pigment cells and
the shade and intensity of the colouring matter enclosed
within the pigmentary granules ; the deeper the colour, the
more abundant the pigment cells, and the greater the depth
of colouring contained in the granules ; thus, of course, the
pigment cells scattered beneath the epidermis of the Ethiopian
are far more numerous than those found beneath that of the

* Mondini (Comment. Bonon, t. vii. 1791, p. 29.) was the first observer
who made accurate microscopic observations on the pigment of the eye.
He stated that the pigment is not simply mucus, but a true membrane
formed of globules disposed in quincunx. The son all but completed the
work which the parent began : he found that each globule is made up of
little black points. Finally Kieser (De Anamorphosi Oculi, 1804, p. 34.),
described the pigmentary membrane as a cellular tissue containing cor-
puscles.

258 THE SOLIDS.

white race, and the colouring matter of the granules is doubt-
less also darker.

In the white, however, a greater or less number of pig-
ment cells is almost invariably found in certain situations, as
in the eye, on the internal surface of the choroid, and the
posterior aspect of the iris and ciliary processes, also between
the sclerotic and choroid: in the skin at certain localities
where it is placed beneath the dermis and epidermis, as in
the areola round the nipples, especially of women, and about
the perinaeum and genital organs.

In the black races, pigment cells follow a similar distribu-
tion in the eye ; but beneath the epidermis, as also under the
nails, they form a continuous stratum composed of super-
imposed layers of cells.

There are yet other situations in which pigment cells have
been encountered : thus Valentin * has signalised the occur-
rence of pigmentary ramifications in the cervical portion of
the pia mater, to which they impart a blackness perceptible
to the unaided sight.

Again, Wharton Jones f has described a thin but evident
layer of brown pigment in the membranous labyrinth of the
ear of man. It has been observed in other mammalia in
which it is still more marked, in the same situation, by
Scarpa, Comparetti, and Breschet. J

The brown spots, known by the name of freckles, with
which the faces of most persons are more or less covered in
summer, are due to a development of pigment cells.

A development of pigmentary matter frequently takes
place as the consequence of disease ; thus, it is of common
occurrence to meet with growths either entirely or in part
composed of pigment cells, the tumours, with the proper
structure of which it usually thus intermingled, being those
of cancer or medullary fungus.

The nature of the pigment-like matter found in the lungs

* Verlauf und Enden der N erven, p. 43.

f Article HEARING in the Cyclopaedia of Anatomy and Physiology, t. ii.
p. 529.

J Recherches sur 1'Organe de 1'Oui'e de 1'Homme, Paris, 1836, in 4to.

PIGMENT CELLS. 259

and bronchial glands of aged persons and animals has been
the subject of much discussion ; nor has it been as yet de-
cided whether it be true pigment, or merely a deposition of
carbon. Pearson * maintained the opinion that the colouring
matter is the powder of carbon, since neither chlorine nor the
mineral acids act upon it.

In those remarkable luces natures, Albinoes, there would
appear to be an absence of pigmentary granules in all parts
of the body, even in the eye : the pigment cells themselves
are stated to exist, but to be wanting in their characteristic
coloured contents.

Pigment cells do not present the same size, form, and cha-
racter wherever they are encountered.

Thus those of the choroid are adherent, large, flattened,
polygonal, mostly hexagonal, with clear nuclei and margins ;
occasionally, however, it happens that both nuclei and cell
wall are obscured by the number and disposition of the con-
tained granules : the cells are mostly of uniform size as well
as shape, in consequence of which regularity they form a
very beautiful microscopic object ; sometimes, however, one
cell is observed to be larger than the rest, octagonal, and
surrounded by a number of cells of smaller size than ordinary,
and mostly pentagonal.

According to Henle f , the contained granules are situated
in the posterior part of each cell, while the nucleus is placed
in its anterior division ; it is this arrangement which allows
of the nucleus being so clearly seen ; in those cases, however,
in which the nucleus is obscured, acetic acid will frequently
bring it into view ; this, if concentrated, will dissolve the cell
wall, set free the granules, and leave the nucleus.

Schwann states that he has seen the pigmentary granules
in the cells of the choroid in active motion.

The cells of the choroid form by their adherence a mem-
brane resembling the most regular and beautiful mosaic
pavement in miniature.

* Philosophical Transactions, 1813, pi. ii. p. 159.
| Anat. Gen. vol. vi. p. 295.

260 THE SOLIDS.

The pigment cells of the posterior face of the iris and
ciliary processes are smaller than those of the choroid, are
for the most part round, or approach that form, and so
filled with corpuscles that the nucleus and margin of the
cell is not usually visible.

In the skin the pigment cells are placed between the
dermis and epidermis ; they do not there form a layer of
equal thickness, but accumulate in the depressions left be-
tween the papillae, forming many superimposed layers,
while on these they are spread out in a single thin layer, and
are often much scattered. It is to this circumstance, as well
as the thickness of the epidermis, and the state of repletion
of the cells, that the varying shades of the colour of the
skin of the same individual depend. In the negro the cells
resemble much in form those of the choroid, being either
perfectly hexagonal, polygonal, or irregularly rounded ; the
nucleus can be well seen in those cells which are less filled.

Amongst the white race, the pigment cells in those situa-
tions in which they occur beneath the skin are fewer in
number, smaller, more rounded, and frequently resemble
little masses of corpuscles rather than distinct cells ; never-
theless it is even here sometimes possible to distinguish the
nucleus and cell wall.

There exists between the internal face of the sclerotic
and the external of the choroid a fibrous tissue of a brown
colour ; this, when these two coats of the eye are separated,
remains attached in part to the one and in part to the other ;
that, however, which adheres to the sclerotic has received a
distinct name, ^and is called lamina fusca. Now the colour of
this layer is due to the presence, scattered amongst the fibres,
of pigment cells of a very peculiar form and construction ; they
are mostly very irregular in size and shape, are marked with
a clear central spot, which indicates the locality of the nu-
cleus, and from the margin of many of them proceed fila-
mentous processes of variable number and size, and the
extreme points of which are mostly colourless, and are not
dissolved by acetic acid.

Pigment cells of analogous construction exist on the ex-

PIGMENT CELLS. 261

ternal surface of the choroid, and also on the cervical portion
of the pia mater.

Mixed up with perfect pigment cells a greater or less
number of pigment granules are always observed ; these are
amongst the smallest objects in nature, and, on account of
their minuteness, it is in them that molecular action in all its
activity is best seen : they are not spherical in form, but are
flattened, so that they appear as discs, lines, or points, ac-
cording as the surface, side, or end presents itself to the eye
of the observer.

It is probable that it is by means of these granules that
pigment cells are multiplied.

Climate, and particular states of the system, as pregnancy,
have much effect in increasing the amount of pigmentary
matter beneath the skin ; from the latter cause the areolae
around the nipples frequently become of a deep chocolate
colour. Of the influence of the former it is scarcely neces-
sary to cite examples : it may be remarked, however, that
freckles are due to the development of pigment cells, brought
about by the action of the summer's sun.

This augmented development of pigment cells may be
rationally explained by the increased determination of blood
to the dermis of the breast from increased activity of function
in that organ during pregnancy, and to the general surface
from the effect of the sun's heat.

It is questionable whether all the varieties of colour of the
human species have not originated in climateric causes, ope-
rating through many ages.

It may also be questioned whether pigment cells are not
susceptible of being developed into those of the epidermis.
If the epidermis of a negro, raised from the surface by means
of a vesicatory, be examined with the microscope, it will be
noticed that the most external cells contain a considerable
amount of colouring matter, which, as this resides in solid
granules and not in a fluid, it is difficult to suppose had en-
tered the cells by endosmosis.

Pigment cells are capable of regeneration in a part in
which they have been destroyed : it is necessary, however,

262 THE SOLIDS.

that the subjacent dermis be not too deeply injured ; the
cicatrices remain for a considerable time nevertheless without
colour.

The skin of the children of negro women does not acquire
its full depth of colouring for some days after birth.

Pigment cells are developed at a very early period of intra-
uterine life. The uses of pigment in the skin are not well
understood ; that in the eye is doubtless of importance in the
discharge of the functions of that organ : it is known that
the Albinoes, in whom it is either absent or exists but in small
quantities, are incapable of supporting a strong light.

Pigment cells of particular forms occur amongst some of
the lower animals. Those of the internal surface of the
choroid of fishes and birds, situated in front of the ordinary
coloured cells, have the form either of short sticks or clubs.
The argentine pigment of the iris and peritoneum of fishes is
composed of elongated corpuscles. The pigment cells placed
beneath the epidermis of the frog are for the most part
stellate.

HAIR. 263

ART. XIII. HAIR.

WE now come to the description of another epidermic modi-
fication, viz. hairs : these, however, are much more complex
in their structure than any which have been hitherto described,
and are less obviously derived from the epidermis.

As in the case of most of the solids described in this
work, we shall first discuss the different particulars relating
to form and size, and next proceed to the description of
structure.

FORM OF HAIRS.

Hairs consist of two parts, a root and a stem : in speaking
of the form of hairs, reference is made to the latter. Hairs
then are elongated, and more or less cylindrical develop-
ments of the epidermis. They depart, however, in most
cases from the character of a true cylinder in two re-
spects ; first, they are not perfectly spherical, but are seen
to be, when viewed transversely, either oval, flattened,
or reniform (see Plate XXIX.) ; and secondly, they are
not of equal diameter throughout, being thickest at about
the junction of the lower and middle thirds of the stem,
of smaller diameter from this part downwards towards the
root, and still more reduced in size as the free extremity
is approached, and which, in a hair which has not been
recently cut, terminates in a point, the diameter of which
is frequently several times less than that of the more central
parts of the shaft. (See Plate XXIX.)

This form is best seen in hairs of medium length, as those
of the whiskers, eyebrows, axillae, and pubis, in which also
the flattened and oval shapes are principally detected.

The hairs which approach most closely thjp cylindrical ar£
those of the scalp,

264 THE SOLIDS.

Henle * makes the interesting statement, that the curling
of hair depends upon its form, and that the flatter the hair,
the more it curls, the flat sides being directed exactly
towards the curve described. From this it follows, that the
hair of Negroes would exhibit in a very marked manner this
flattened form.

SIZE OF HAIRS.

Hairs differ remarkably in size, both as regards length
and breadth : they differ not merely in different individuals,
in different localities in the same person, but also in any one
given situation, as the scalp or pubis.

The hairs of the scalp are the longest ; those of the scalp
of women are many times longer than those of the same part
in man, and according to the measurements of Mr. Wilson,
they are also thicker. Next in length come the hairs of the
chin of man. Amongst women, instances have been known
of the hair extending from the scalp to below the feet, and
the beard of man not unfrequently reaches to the waist.

The shortest and smallest hairs are those covering the
general surface of the body, and which are reduced to
mere down (lanugo).

The thickest hairs of the body are those of the whiskers,
chin, pubis, and axillae, the finest those distributed over the
general surface; the hairs of the scalp are of intermediate
diameter.

The hairs of children are finer than those of adults, and
those of the head of men than those of women.

It cannot be doubted but that frequent cutting and
shaving of the hair tends to increase its thickness.

STRUCTURE OF HAIR.

Each hair admits of division into two parts, the root and
stem, and each of these, again, allows of still further sub-

* Anat. Gen., vol. vi. p. 314.

HAIR/ 265

division : thus the root consists of the prolongation of the
hair proper, or stem, terminating in an expanded portion
which has been termed the bulb, and of a double sheath;
the stem also is divisible into cortex, medulla, and inter-
vening fibrous portion, which constitutes the chief bulk of
the hair. (See Plates XXVIII. and XXIX.)

These divisions of the root and stem of hairs suggest its
comparison to a tree, the stem of which also resolves itself
into cortex, medulla and intervening woody or fibrous sub-
stance. The comparison is also heightened by the similar
relation in which both stand to the parts around them, viz.
the soil in the case of the tree, and the dermis in that of the
hair.

Root of Hair.

We will first describe the root, because it is the source
from which the hair is developed : this, as already noticed,
consists of two parts, the sheath and the bulb.

The Bulb. — The bulb is the expanded and basal portion
of the stem of each hair : it is usually two or three times
the diameter of the hair itself, and is sometimes excavated
below : it is constituted of granular cells, which are either
circular, angular, or elongated in form, the spherical cells,
form the extremity of the bulb, the polygonal ones its sur-
face, and the elongated cells are placed above the spherical
ones, of which they are modifications, and beneath the an-
gular cells of the surface of the bulb. Acetic acid will be
found useful in displaying the cellular structure of the bulb.

In healthy hairs this bulbous portion of the stem is al-
ways coloured, which is not the case with grey hairs. (See
Plate XXVIII.)

The part of the stem of the hair immediately above the
bulb, and included within its sheath, exhibits the structure
of the body of the stem itself, being divisible into scaly
cortex, fibrous intervening substance, and granular medulla.

Sheath. — The bulb and lower portion of the stem of the

z 2

266 THE SOLIDS.

hair is included in a sheath consisting of two distinct layers,
an outer and an inner. (See Plate XXVIII. fig. 1.)

The outer layer is an inversion of the epidermis : it first
merely encircles the portion of the stem of the hair beneath
the level of the epidermis : it next surrounds the inner layer
of the sheath, to which it soon becomes intimately adherent ;
finally, it forms a cul de sac around the bulb of the hair.

The fact of the inverted sheath of the epidermis forming a
pouch around the bulb of the hair, may be inferred from the
circumstance, that when the epidermis peels off as the result
of decomposition, the hairs usually come away entire with it ;
its continuation moreover around the bulb may be shown in
transverse sections of the skin of the axillae and whiskers, in
which the hairs penetrate into the subcutaneous fatty sub-
stance. (See Plate XXVIII. fig. 1.)

This outer layer is colourless., is possessed of considerable
thickness, and is evidently made up of granular cells similar
to young epidermic cells.

In most hairs, whether coloured or uncoloured, which have
been forcibly removed from the skin, this outer layer is usually
torn across, the rupture occurring almost invariably at a little
distance from the bulb of the hair : the root of the hair then
below this breach of continuity consists only of the inner layer
of the sheath and of the stem of the hair ; and at this situa-
tion, the root to the naked eye appears contracted : this is,
however, but an appearance, the result of the absence of the
outer layer, and of the expansion of the stem into the bulb.
(See Plate XXVIII. fig. 2.)

The inner layer of the sheath is an eversion or revolution
of the epidermis, and is an offset or continuation of the outer
layer, commencing at the lower part of the bulb : it is colour-
less, possessed of considerable thickness, its diameter being
about one-third of that of the stem of the hair in its thickest
part: it tears readily in the longitudinal direction with a
somewhat uneven fracture ; and hence may be inferred to be
of a fibrous constitution, as may be shown to be the case : its
inner surface is marked with reticulated lines, the impressions
of the cortical scales of the shaft of the hair.

HAIR. 267

This inner layer is not of equal diameter throughout, but
tapers gradually from below upwards : it is well defined both
internally and externally, except where it comes in contact
with the bulb internally, with which its inner edge or surface
becomes incorporated ; above it terminates in a thin border
at a little distance below the level of the skin. (See Plate
XXVIII. Jiff. I.)

The outer layer, although adherent to the inner at its
lower part, does not become incorporated with it : the latter,
except at the point indicated, preserves everywhere its inde-
pendence and individuality. The two layers, it will thus be
seen, might with much convenience have been described, as
two distinct sheaths, an inner and an outer : to do so, would
be, however, to lose sight in some measure of the similar
origin and nature of the two.

In the fact, however, of the inner sheath exhibiting a
fibrous structure, and of its incorporation with the bulb, it
would appear to have more structural affinity with the fibrous
portion of the stem of the hair itself than with the outer layer
or cellular sheath.

This inner layer might be appropriately termed the
" modelling sheath," since it doubtless regulates the form and
dimensions of the shaft of the hair, the substance of which
when first developed is soft and plastic. Henle describes
the inner layer as fenestrated : this structure I have never
seen exhibited.

Shaft of the Hair.

The stem or shaft of the hair is divisible, as already ob-
served, into cortical, medullary, and fibrous portions.

Cortex. The cortical part of the hair consists of a layer of
scales, imbricated upon each other after the manner of tiles
upon the roof of a house. (See Plate XXIX.) These scales
are be'st seen in the larger hairs of the whiskers and pubis, and
in the small downy hairs ; they are smaller than the ordinary
cells of epidermis, and are rarely seen to be nucleated.
Maceration of the hair in sulphuric acid causes them to fall

z 3

268 THE SOLIDS.

off, and in this way their size, form, and structure, may be
satisfactorily studied.

The scales are absent from the points of the finer hairs.
In consequence of their imbrication upon each other, their
little thickness, and of the double contour presented by their
free edges, they frequently convey the appearance rather of
anastomosing fibres running round the hair than of distinct
scales.

A hair rolled between the fingers always advances in a
given direction, viz. towards the apex : this results in part
from the tapering form of the hair, and partly from the more
or less spiral disposition of the scales.

Fibrous Layer. — The fibrous portion of the stem of the
hair constitutes its chief substance and bulk, forming two-
thirds of the entire diameter, one-third on each side of the
medulla. In hairs which are not too dark, the constituent
fibres may be seen in situ : they are most palpably brought
into view either by scraping the hair with a knife or by
crushing it after maceration in sulphuric acid : they are also
best seen in the larger hairs and near the centre of the shaft.

Henle describes the fibres as flat, with uneven edges, and is
in doubt as to whether they are branched or not. To my
observation they appear much smaller than they are stated
to be by Henle, and are spherical and simple. (See Plate
XXIX.)

These fibres have a cellular origin, and are formed by the
elongation of the inner cells of the bulb in which their gra-
dual extension into perfect fibres may be traced.

They are stated by most observers not to extend to the
extreme point of the hair; and the same statement is like-
wise made in reference to the medullary canal and cortical
scales. Of what, then, it may be fairly asked, is the point of
the hair constituted, since every structure entering into the
formation of the shaft is denied to it ? The assertion that
the fibres do not extend to and form the apex of the hair is
evidently erroneous. In the examination of the points of a
number of hairs which have not been recently cut, fibres often

HAIR. 269 k

separated from each other and loose will frequently be de-
tected. (See Plate XXIX.)

The whole of the fibres of the stem, however, do not ex-
tend its entire length, the majority terminating long before
the extremity is attained ; and it is to this fact that the at-
tenuated form of the hair is attributable. In some hairs the
fibres are seen to terminate at regular distances, their points
describing transverse lines on the stem of the hair.

The splitting, of such common occurrence in hairs which
are allowed to attain an excessive length, is due to a separa-
tion of the fibres from each other.

The fibrous portion in young and healthy hairs is coloured.

Medullary Canal and Medulla. — In most hairs which are
not of too deep a colour a medullary canal may be detected
running up the centre. This commences in the upper por-
tion of the bulb, runs along the shaft, but ceases as it ap-
proaches the apex : its diameter varies with that of the
hair itself, but usually bears the proportion of a third of its
thickness. (See Plates XXVIIL and XXIX.)

Henle is uncertain whether this canal is lined by a distinct
membrane or not, but inclines to the opinion that it is so.

The medulla or contents of this canal exhibit a granular
appearance, and are made up of pigment granules, a few
perfect pigmentary cells, and particles of coloured oil : it is
therefore in the medulla that the greatest amount of colouring
matter of the hair is situated. (See Plate XXVIIL fig.\.)

At the very commencement in the bulb of the hair the
medulla has distinctly a cellular origin.

In young and healthy hairs it is also continuous through-
out the entire extent of the medullary canal ; in old and dis-
coloured hairs, on the contrary, its continuity is frequently
interrupted by distinct intervals, and it only partially fills the
cavity of the canal even where it is present.

The medullary canal and medulla is best seen in the larger
hairs, which are not of too deep a colour, and in grey hairs :
in the fine and downy hairs of the general surface of the
body, the canal and its contents, as a necessary consequence,
are almost entirely absent.

7. 4

270 THE SOLIDS.

In some rare instances two medullary canals have been
observed in the same hair. In the sable the medulla has a
distinctly cellular structure throughout.*

FOLLICLE OF THE HAIK.

Each hair is implanted in a distinct depression in the
dermis, the base of which especially is freely supplied with
nutrient vessels : this depression is also lined by an invagi-
nation of the epidermis, and which becomes ultimately the
outer layer of the sheath of the root of the hair as already
described. (See Plate XXVI. fig. 3.)

Between this layer, however, and the shaft of the hair for
a short distance before it rises above the level of the skin, a
space, or cavity is left, into this space the canals of one or
more sebacious ducts generally open, and in it also entozoa
frequently develope themselves.

It sometimes happens that two or more hairs are contained
in the same follicle (see Plate XXVI. fig. 3.) : in these
cases, however, each hair has a distinct modelling sheath. In
some .animals the location of a number of hairs in one sheath
is the ordinary mode of arrangement ; in the pig, for ex-
ample, the hairs are usually thus associated in threes, as also
occasionally in man.

The hair follicle or crypt is best seen by examining thin
vertical slices of the skin.

The length of the l;air follicle and the consequent depth
of implantation of the hair varies, but is often equal to the
twelfth or sixteenth of an inch ; the hairs of the head, of the
whiskers, of the pubis, and of the axilla penetrate into the
subcutaneous cellular tissue ; those of the eyelids and ears to
the subjacent cartilages : the roots of hairs in general, how-
ever, do not penetrate beyond one half the depth of the
corium, in the substance of which they are buried.

It is usually stated that the bottom of the follicle is oc-

* The first accurate observations on hair were made by Hook, Mico-
graphia, 1667, Obs. 32. tab. v. fig. 2., and Leeuwenhoek, Opera, t. iv. p. 46.

HAIR. 271

cupied by a papilla furnished with blood vessels and nerves,
on which the bulb of the hair immediately rests ; and that
it is owing to this papilla that the base of the bulb, when
removed, exhibits a concavity. This description, in the case
of tactile hairs, may be correct, but is surely not so when
applied to hairs in general. Each hair does indeed rest upon
a papilla, but it is one which is destitute of blood vessels
and nerves, and which is cut off from all direct vascular
communication by the cul-de-sac formed by the outer lamina
of the sheath. This papilla may be described as a compound
cellular vesicle, and is probably the true germ of the hair ; it is
on it that the bulb of the hair is situated, and which occasions
the depression which this generally displays when it has been
forcibly extracted. This germ is best seen in grey and light
coloured hairs.

GROWTH OF HAIR.

The growth of hair takes place at the root, and is the
effect of the development of new cells which is continually
in progress in the bulb, and which afterwards become
modified into those of the scaly cortex and fibrous stem ;
these new cells, coming behind the older ones, continually
press them forwards, and thus occasion the elongation of
the hair.

But the elongation of each hair takes place in a manner
very different from that just mentioned, not from the de-
velopment of new cells, but by the gradual elongation and
extension of the cells already formed after they have quitted
the bulb, and when they come to form the shaft of the hair.
This mode of elongation, it can scarcely be called develop-
ment, is proved by the gradual tapering of the hair which
takes place after the point has been removed : of the truth of
this 'fact not the slightest doubt can be entertained.

At the period of puberty a growth of hair takes place
in certain situations in which previously it was not ap-
parent, as on the chin, cheeks, in the axillae, and on the

272 THE SOLIDS.

pubis, abdomen, and chest ; this development is an effect of
the great functional activity which exists at that period, and
which is the occasion of the increased and rapid growth of
the several constituents of the body which then takes place.

The earliest periods at which the rudiments of hairs in the
human foetus have been observed is from the third to the
fourth month : the hair follicle is formed in the first place,
next the bulb, and then the sheath and stem of the hair,
which, in the early period of its development, is curved
upon itself. •

Hairs are occasionally developed in certain peculiar situa-
tions, as on the mucous membrane of the conjunctiva, the
intestines, and gall bladder, in the ovaries, and in steatoma-
tous and encysted tumours.

Hairs may be transplanted, and, it is said, will grow after
such transplantation in consequence of the adhesions and or-
ganic connexion established between them and the adjacent
tissues, — a fact of which practical advantage might be taken
if correct.

When a hair has obtained the full term of its develop-
ment^ according to the researches of Eble, it becomes con-
tracted just above the bulb : this change probably announces
its death and approaching fall.

REGENERATION OF HAIRS.

Hairs are peculiarly susceptible of being affected by the
condition of the health, even more so than the epidermis. If
this be vigorous, as a rule to which there are many exceptions,
it will be found that the hairs themselves are thick and firmly
set in the skin : if, on the contrary, the powers of the system
be debilitated from any cause, the hair will either fall off
spontaneously, or a very slight degree of force will serve to
dislodge them from their connexions.

If the bases of those hairs which fall out of themselves be
examined, or which are removed by combing and brushing,
it will be seen that the bulb alone has come away, the entire
sheath and germ remaining behind. In such cases the hair

HAIR, 273

is doubtless regenerated, and after its regeneration is usually
stronger than it was previously. (See Plate XXIX.)

It has not yet been ascertained by positive experiment
whether the hair is capable of reformation in those instancss
in which both bulb and sheath have been removed : it is
most probable, however, that where they have been entirely
abstracted, no renewal of the hair could ensue.

It is possible that in some cases the apparent regeneration
of the hair arises, not from the development of new hairs
in the primitive sheaths and 4ipon the old germs, but from
the formation of new hair follicles and germs : of this, how-
ever, no proof has as yet been given.

That a regeneration of new shafts of hair is continually in
progress, whether from new germs or the older ones is not
known, is proved by the detection of small and pointed hairs
just emerging from the skin in the scalp of even old persons.

NUTRITION OF HAIR.

Hairs are nourished in the same way as the epidermis
itself; that is, they do not receive into their own structure
either blood vessels or nerves, but derive their nutriment
from vessels which are so distributed as to come into close
contact with the tissues to be nourished.

This indirect reception of the nutrient plasma explains the
very great susceptibility of the epidermis and its several
modifications to be influenced by causes affecting the general
health, and in consequence the circulation and the qualities of
the circulating fluid.

The epidermic tissues being placed in situations the most
remote from the centre of the circulation, are endowed with
but a feeble degree of vitality, and which is readily de-
stroyed by causes affecting the amount and nature of the
circulating fluid received by them.

The nutrient vessels and sentient nerves of each hair are
distributed around and outside the sheath, and not in a raised
papilla as generally described, although this may really be the

274 THE SOLIDS.

case in the large hairs of the whiskers of some animals, as,
for example, the tactile hairs of the seal, &c. The fact of
the hair usually penetrating below the level of the true skin
and into the subcutaneous fatty tissue seems to disprove the
notion of a distinct and vascular papilla.

DISTRIBUTION OF HAIRS.

Hairs are distributed over the entire surface of the body,
with the exception of the palftis of the hands, soles of the
feet, and last phalanx of the toes and fingers : there are, how-
ever, situations in which they are developed in increased
quantities, as on the integument of the scalp, on that of the
eyebrows, on the margins of the ciliary cartilages, and after
the period of puberty, on the chin, cheeks, axilla, pubis,
abdomen, chest, and at the entrance of the nares and ears.

The number of hairs found in these several situations
differs very considerably in different individuals, according
to age and condition of health.

Individuals of the male sex also are generally more hairy
than females, in whom also no development of hairs takes
place on the chin, cheeks, chest, and abdomen.

Of the number of hairs which exist on the entire surface
of the body, some idea may be formed from the measurements
of Withof. The quarter of a square inch furnished 293 hairs
at the synciput, at the chin 39, at the pubis 34, on the fore-
arm 23, at the external border of the back of the hand 19,
and on the anterior surface of the thigh 13. Upon the same
extent of surface Withof counted 147 black hairs, 162 brown,
and 182 flaxen.

Hairs of great length and strength are often developed in
considerable quantities in different parts of the body, in moles
and nsevi.

DIRECTION OF HAIR.

The hair follicles are not placed vertically in the skin, but
obliquely, and the hairs which issue from them consequently

HAIR. 275

themselves run in the same oblique direction. (See Plate
XXVI. fig. 3.)

The apertures of most of the follicles look downwards, and
hence we find in most cases that the points of the hairs, when
fully developed, are similarly directed.

In addition, however, to this general arrangement and dis-
tribution, it will be seen that in early life the hair follicles are
disposed in lines, the apex of one follicle nearly touching the
base of the next : the lines thus described are not straight,
but are more or less curved, and divergent or convergent
after the manner of the lines upon the case of an engine-
turned watch : the hairs which issue from the follicles thus
take particular and determinate sweeps, which it is un-
necessary to describe in detail.

It occasionally happens from some cause or other that
the hair follicles are implanted in a manner the reverse of
that which should obtain: this is especially seen in those
of the scalp of children, in whom frequently certain tufts
of hair grow up, and incline in a direction opposed to that of
the contiguous hair. This mal-disposition of the hair is the
source of much trouble and annoyance to anxious nurses and
mothers, who spend much time in endeavouring to bring the
refractory lock into order.

In this endeavour there can be no question but that it is
possible to succeed, as is proved by the very different arrange-
ment which the hair of the head is made to follow in accord-
ance with the manner in which it is dressed.

ERECTION OF HAIR.

Man, to a certain extent, and many animals in a consider-
able degree, possess the power of erecting the hairs. This
power in man is limited to the hairs of the head, in many
annuals it is much more general.

Most persons on sudden exposure to cold, and on expe-
riencing of any emotion of fear or horror, feel a creeping
sensation pass over the head : this sensation is accompanied

276 THE SOLIDS.

by a certain degree of erection of the hair, but not indeed to
such an extent as to cause it " to stand an end." Now this
erection is the result of the distribution of fibres of elastic
and contractile tissue throughout the substance of the corium,
and which interlacing amongst the hair follicles, occasion the
erection of the hairs themselves.

The distribution of these fibres, ajid their connexion with
the bases of the hairs, are well seen in the skin of the hog.

COLOUR 0F HAIR.

The colour of the hair depends upon the same cause as
that of the skin and eye, and is due to the presence of pigment
granules and cells; these are contained principally in the
medullary canal, but are also interspersed between the fibres
of the stem ; they first become manifest in the upper portion
of the bulb of the hair.

The depth of the colour of the hair very generally bears
a relation to the development of pigmentary matter in other
parts of the system, as in the eye and beneath the skin. To
this rule, however, some remarkable exceptions are occa-
sionally encountered.

The colour of the lighter hairs, as the red and flaxen,
would appear to depend less upon the number and depth of
colouring of the pigment cells and granules, than Upon the
presence of minute globules of a coloured oil.

In the hair of Albinoes but little colouring matter is pre-
sent, and in grey hairs also, the colour has deserted the pig-
ment cells and granules.

Hair is decolorised by long contact with chlorine.
It is generally stated as an undoubted fact, that the hair
may turn white or become colourless under the influence of
strong and depressing mental emotions in the course of a
single night. This singular change, if it does ever occur
in the short space of time referred to, can only be the result
of the transmission of a fluid possessing strong bleaching pro-
perties along the entire length of the hair, and which is
secreted in certain peculiar states of the mind.

HAIR. 277

GREY HAIR.

If a grey hair be contrasted with an unaltered one from
the head of the same person, the following differences will be
noticed between the two. The grey or white hair will be
observed to be almost colourless, the bulb and fibrous portion
will be destitute of colour, the medulla alone retaining a
slight degree of coloration : this, however, is collapsed, and
in place of being continuous throughout its length, will be
seen to be interrupted at intervals. (See Plate XXVIII.

fig- 2.)

The unaltered hair, on the contrary, is distinguished by
characters the reverse of those exhibited by the grey hair ;
thus the bulb, stem and medulla are all deeply coloured, and
the latter fills the entire cavity of the medullary canal, and is
continuous throughout. (See Plate XXVIII. fig. 1.)

Grey hair retains a considerable degree of vitality, as is
proved by its growth continuing for many years after its loss
of colour.

PROPERTIES OF HAIR.

Hairs are remarkable for their strength, their elasticity,
durability, and for the difficulty with which they undergo
the process of decomposition : their strength results probably
from their fibrous constitution ; in their elasticity and dura-
bility, they partake of the character of all horny structures.

The strength of hair is proved by the fact that a single
hair will bear a weight of 1150 grains.

Its elasticity is shown by the readiness with which each
hair, when extended, returns to its original size and shape,
as well as by the fact that the numerous hairs forming a
curl or lock will recover their ordinary form and disposition
after extension.

Its durability is shown by the persistence of hairs through-
out many years of life.

Lastly, its indestructibility is proved by the occurrence of
hairs in the tombs of persons buried for ages.

278 THE SOLIDS.

A hair, however, which has been very forcibly extended will
not return to quite its original length, but will remain a
certain degree longer than it was previous to the extension.
A hair may be extended a third of its length without break-
ing ; elongated a fifth, it remains a seventeenth longer than
it was before ; it continues a tenth longer after having been
extended a fourth, and a sixth only after having been drawn
out as much as possible.

Hairs, when they are dry, become electrical by rubbing
and emit sparks : this is well known with respect to the coat
of the cat, and Eble has observed the same thing to occur
in man.

Hairs are also eminently hygroscopic, and imbibe moisture
from the air and from the skin, in consequence of which they
lose their set or curl, and become flaccid and straight.

Nitrate of silver blackens the hair, a sulphuret of silver
being formed, and it is of this ingredient that • the majority
of hair dyes are chiefly constituted. The concentrated
mineral aicds, especially the nitric, dissolve the hair, as does
also caustic potash.

When heated hairs take fire and burn with a fuliginous
flame, emitting the odour of bone, and leaving a residue
of carbon. To dry distillation, they yield a quarter of their
weight of carbon, which is difficult to incinerate, the pro-
ducts being empyreumatic oil, water charged with ammonia,
and combustible gases, which comprise sulphureted hydrogen.
The ashes contain oxide of iron, traces of oxide of manganese
and silica, and of sulphate, phosphate, and carbonate of lime.

THE HAIRS. OF DIFFERENT ANIMALS.

The precise structure of the hairs of different animals
varies considerably : those of the mammalia resemble the
hairs of man, or differ only in the degree of their develop-
ment, as the whiskers of the carnivora and rodents, and manes
and tails of horses, the bristles of pigs, &c. : it is in these
largely developed hairs that the structure can be best deter-

HAIR. 279

mined : thus in the majority of them it is stated to be easy to
detect the vessels and nerves of the papillae on which the bulb
rests, and which penetrate into it : nerves have been detected
by Eble in the cat *, by Rapp in the seal, porcupine, and
many other animals f , and by Grerber in the pig. if

In the hairs of the musk deer there seems to be no separa-
tion of parts into scaly cortex, fibres and medulla, the entire
hair being uniformly cellular.

In that of the sable the fibrous portion is absent, and there
is only scaly cortex and cellular medulla.

In the hairs of most rodents the medulla is divided by dis-
sepiments, and in other animals, as the sable, it is composed
of large and distinct cells.

The hairs of the mouse, bat, and martin are branched or
knotted.

In the spines of the porcupine and hedgehog the inner
bark penetrates in longitudinal bands into the cavity of the
medullary canal, and thus divides the medulla itself into in-
complete segments ; the transverse view of such spines repre-
sent a starred or rayed figure.

In birds, hairs are replaced by feathers, which are to be
regarded as modified hairs.

THE USES OP HAIR.

The uses of hair are manifold.

In certain situations, as on the head, it is to be regarded
as an ornament.

In other localities, as on the cheeks and chin, it imparts
character and expression to the face.

In others again, as on the pubis and about the genital
organs, it serves the purpose of concealment.
t

* Von den Haaren, t. 11. p. 19.

f Verrichtangen des freuften Nervenpaares, p. 13.

J Allgemeine Anatomie, p. 79.

A A

280 THE SOLIDS.

The general use of hair wherever encountered, it being a
non-conductor of caloric, is to preserve the warmth of the
system.

Those situated at the entrance of the nares and meatus
auditorius externus are placed there to prevent the entrance
of foreign bodies, insects, &c.

It is difficult to assign any use to the hairs of the axilla.

It is very probable that hairs have other uses, and that
they exert some influence in regulating the electric condition
of the body.

CARTILAGES. 281

ART. XIV. CARTILAGES.

CARTILAGES are amongst the most solid structures entering
into the constitution of the animal organization ; they are,
however, not less remarkable for their elasticity and flexibility
than for their solidity.

The essential element of the several fluids and solids
hitherto described in the course of this work we have seen to
be cells : this cellular composition is exhibited in a high degree
by cartilages.

The texture and colour of the cartilaginous tissue varies
considerably : it presents either a white or bluish white, semi-
transparent and homogeneous appearance, or it is yellow,
and exhibits a fibrous texture.

These differences of texture and of colour indicate a dif-
ference of structure, upon which a division of cartilages into
the true and fibro-cartilages has been based.

TRUE CARTILAGES.

True cartilages consist of cells, contained in cavities, which
are themselves formed in a solid and hyaline intercellular
substance.

They comprise all those cartilages which cover the articular
extremities of the bones (that of the glenoid fossa and of the
head of the inferior maxilla alone excepted), the cartilages
of the entire respiratory apparatus (with the exception of
the epiglottis and the cuneiform cartilages), those cartilages
which are to a considerable extent free and independent, and
which 'have been denominated figured cartilages, as those of
the ribs, the ensiform cartilage ; the trochlea of the eye, the
nasal cartilages, and the Corpuscula triticea in the lateral
hyo-thyroid ligaments. (See Plate XXX. Jigs. 1 and 2.)

A A 2

282 THE SOLIDS.

The true cartilages are distinguished from the fibro-car-
tilages by their bluish and transparent aspect.

Structure of True Cartilages.

True cartilages consist, as already mentioned, of hyaline
matrix, cavities, and cells ; each of these constituents will be
described in succession.

Hyaline Matrix. — The intercellular substance, or hyaline
matrix, although it does not usually present any distinct
traces of organization, yet contains, scattered through it,
numerous granules of different sizes, and many of which are
to be regarded as the cytoblasts from which new cells are
continually being developed.

The amount of this intercellular substance varies in dif-
ferent cartilages, and is greater in fully developed than in
very young cartilage.

Cavities. — The cavities of true cartilages vary both in
size and form ; in shape they are irregular, although for the
most part elongated.

They are, in most cases, to be regarded as simple excava-
tions or fossae in the hyaline matrix ; in others, however, it
would appear from the observations of Henle *, Bruns |3 and
Schwann J, that they are lined by a distinct membrane, and
which is indicated by a double contour, by the difficulty
experienced in setting free the contained cells, and by the
fact, that by boiling, the intercellular substance is dissolved,
while the cavities remain as distinct corpuscles.

Such cavities would stand in the relation of parent cells to
those which they include.

Cells. — The cells of cartilages are very different from those
occurring elsewhere in the animal organization ; they are
distinct in their form and in the character of their contents.

Cartilage cells, like the cavities in which they are enclosed,
are irregular in size and shape ; they are, however, generally

* Anat. Gen., vol. vii. p. 364. f Allg.'Anat., p. 215.

j Mikrosk Untersuch.

CARTILAGES. 283

elongated, sometimes flattened and compressed ; at others,
they are perfectly spherical : these several shapes depend
upon the degree of pressure to which the cells are subject,
and which is greatest at the free margins of the cartilages
where the compressed form occurs, and least in the centre
where the spherical cells are chiefly encountered. Each cell
contains a nucleus which is either smooth or granular ; it
includes also very generally one or more shining and globular
bodies of an oleaginous or fatty nature, and which, in many
cases, are to be regarded as transformed nuclei.

The cells usually lie as it were scattered irregularly
throughout the intercellular substance ; in some cases, how-
ever, they are arranged in definite order ; thus in the con-
densed margin of all the true cartilages the cells are com-
pressed, and lie with their long axes disposed parallel to the
surface. (See Plate XXX. Jig. 1.) Again, in the ribs, they
radiate in straight lines from the centre towards the circum-
ference : this disposition of them accounts for the fibrous
fracture which they exhibit when broken across, as also for
the fact of their being divisible into thin transverse layers.
The linear arrangement of the cells in the fully developed
cartilages of the ribs is very frequently not perceptible.

In very thin cartilaginous laminae, as those forming the
ahe of the nose, the difference in the form of the central and
periphral cells does not exist, the entire intercellular sub-
stance being filled with small and rounded cells.

The cells usually occur singly in the hyaline matrix ; they
are, however, frequently encountered in groups of two, three,
or four cells, each of which is distinct, and describes a more
or less regular segment of a circle : this disposition of the
cells is connected with their mode of multiplication, as will
be seen hereafter.

Again, groups of secondary cells sometimes occur espe-
cially in the iritervertebral fibro- cartilages, included in the
merr/brane of the primary or parent cell. (See Plate
XXXI.)

Moreover, Henle * has noticed a peculiar arrangement of

* Anat. Gen., vol. vii. p. 366.
A A 3

284 THE SOLIDS.

the cells of the cartilages which cover the articulating surfaces
of the larger bones. On the free surface the cells are as in
most cartilages small, flattened, and disposed horizontally ;
the deeper seated cells become larger and longer ; their axes,
on the contrary, being directed either vertically or obliquely
to the surface ; sometimes also the cells although separated
by distinct intervals, are arranged the one above the other
in such a manner as that the superior appears to be a con-
tinuation of the inferior ; at others an inferior cell appears
to divide into two others, placed above it, and thus represents
a bifurcation. Henle also states, that he has seen not unfre-
quently the outline of a cavity prolonged from one longi-
tudinal series of cells to a neighbouring series. It is very
possible, Henle goes on to observe, that these cavities form
part of a system of elongated canals, which taking an undu-
lous course, and sometimes bifurcating, traverse the cartilage
from its inferior to its superior surface, and which, when one
makes a section, are divided into two portions, the one re-
maining in one segment, the other in the other segment.
This structure, he proceeds to remark, explains sufficiently
why articular cartilages exhibit a fibrous fracture, and why
the earlier observers believed them to be composed of fibres
which ran perpendicularly to the thickness.

This ingenious notion of Henle, although it serves to ac-
count for some hitherto unexplained phenomena connected
with the articular cartilages, is yet of very doubtful application
even to them, and certainly no such arrangement of the cells
and cavities as that just described belongs to the majority of
true cartilages, or to any of the fibro-cartilages.

Near the surface the articular cartilages are more lami-
nated, and may be separated into thin lamellae.

In the smaller articular cartilages the number of cavities
and cells is more considerable, and the superficial layer of
cells is not so well marked : the periphral cells are small
indeed, but for the most part rounded ; a few are found in
the neighbourhood of the bone of an elliptical figure, but the
middle layer presents circular cavities, with cells which are
either single or multiple.

CARTILAGES. 285

Nuclei. The nuclei contained in cartilage cells are mostly
granular, but sometimes present a smooth aspect, and then
are scarcely to be discriminated from particles of oil or fat :
in form they are sometimes rounded, but in general they are
irregular in shape, and follow more or less closely the contour
of the cells in which they are enclosed ; they also frequently
enclose a nucleolus.

Usually but a single nucleus is contained in each cell ;
occasionally, however, two, three, and even several are in-
cluded within it ; and sometimes it happens that one or more
of these is invested by a distinct cell membrane. (See Plate
XXXI)

The cells also include, as already remarked, particles of oil
of a globular form and of a shining aspect : it has been sug-
gested that these may probably in some cases be transformed
nuclei.

The distinction of cartilages into true and fibro-cartilages,
although useful for the purposes of classification, is to some
extent artificial, since, on the one hand, some of the true
cartilages, as old age approaches, become converted into fibro-
cartilage, and on the other, the fibro-cartilages themselves, in
the early period of their development, do not contain fibres,
the cellular substance being hyaline, and identical with that
of true cartilages.

The conversion of hyaline cartilage into fibro-cartilage has
been observed to occur only in those cartilages which are
subject to become ossified, as those of the ribs, the thyroid, &c.

Where ligaments are inserted into true cartilaginous tissue,
this in the neighbourhood of such insertion always exhibits a
fibrous structure, in consequence of the fibres of the ligament
penetrating into the intercellular substance. These fibres
are of a nature totally distinct from proper cartilage fibres, as
will be seen hereafter.

FIBRO-CARTILAGES.

Fibro-cartilages differ chiefly from true or hyaline car-
tilages, in that the homogeneous intercellular substance is

A A 4

286 THE SOLIDS.

replaced in them by fibres endowed with elasticity ; a trans-
formation of structure of which we have seen that certain of
the true cartilages are susceptible. (See Plate XXXI.)

The fibro-cartilages include those of the articulations which
are united by synchondrosis, as the invertebral cartilages, and
that of the symphysis pubis ; the epiglottis and the cuneiform
cartilages ; the articulating cartilages of the glenoid cavity,
and of the head of the superior maxillary bone ; the inter-
articular cartilage of the sterno-clavicular articulation; the
cartilages of the ear, of the Eustachian tube, of Santorini,
and those of Wrisberg.

There are, however, other differences besides the structural
one alluded to : thus, fibro-cartilages are more opaque than
the true, are of yellow colour more or less deep, and are en-
dowed with a higher degree of elasticity and flexibility.

The fibres do not follow the same distribution in every
fibre-cartilage : thus, in the tube of Eustachius, in the
symphysis pubis, 'in the interarticular cartilage of the sterno-
clavicular articulation, in those of the tempero-maxillary
articulation they are placed nearly parallel to each other ;
in the intervertebral cartilages they ascend vertically from
one osseous surface to the other ; in the cartilages of the
epiglottis and ear they are curved and interlacing.

In the outer part of each intervertebral cartilage the fibres
form a distinct and compact stratum of a yellow colour, no
cartilage cells in that situation intervening between them ;
the number of fibres, however, gradually diminishes towards
the centre of the cartilage, which at the same time becomes
less and less dense and firm, until at length in the very axis
it is semifluid.

The cells of fibro-cartilages do not differ very materially
in form and structure from those of true cartilages ; they
usually, however, contain more fat, are more readily separable
from the fibrous base in which they are lodged, and more
frequently encountered in the condition of parent cells.

The cells of the intervertebral cartilages and of the epi-
glottis present some interesting forms and modifications :
thus, the cells which are situated in the harder parts of

CARTILAGES. 287

those cartilages are, on a vertical section, seen to be narrow
and much elongated; while many of those imbedded in their
soft and central parts are large and perfectly globular ; many
others of these, again, are in the condition of parent cells, and
enclose either numerous nuclei or else many perfectly formed
secondary cells; lastly, cells occasionally present themselves
made up of concentric vesicles enclosed one within the
other. Groups of adherent nuclei are also frequently met
with deprived of an investing membrane. For representa-
tions of these several forms of cells, see the figures.

Henle* describes as occurring in the epiglottis certain
large, spherical, or oval cells, presenting in their interior
an oblong cavity from which proceed little branched tubes,
which extend in all directions, even to the surface of the
cells. These cells would appear to have some analogy with
the osseous corpuscles. I have made diligent search for
them in the epiglottis, but hitherto have failed to meet with
them.

The fibro-cartilages are not soluble to the same extent in
boiling water as the true, which are almost entirely so, and
therefore yield less chondrine or jelly. The cells of these
cartilages also resist the action* of the water for a longer period
than the intercellular substance, f

NUTRITION OF CARTILAGE.

Cartilages are amongst the number of non-vascular sub-
stances — that is, they do not, in general, receive into their
own tissue distinct blood vessels, but derive their nourish-
ment from those which are distributed to the parts adjacent
to them.

Thus, the articular cartilages are supplied with nutriment

from the vessels which are so freely distributed to the ex-

t

* Anat. Gen., vol. vii. p. 370.

f Meckauer (Cartilag. Structura, 1836,) appears to have been the first
to give, under the direction of Purkinje, a complete and accurate de-
scription of tho cartilages of the human body.

288

tremities of the bones : in young children and sometimes
even in adults the synovial membrane which covers the free
surfaces of the cartilages also carries vessels which assist in
their nourishment.

The independent or figured cartilages, as the ribs, &c.,
are surrounded by a membrane, composed of condensed eel-
lular tissue, called the perichondrium : in this membrane the
vessels which afford nutriment to the enclosed cartilages
ramify. The ribs, moreover, contain grooves or canals,
which, commencing on the inner edge of the rib, first run
towards the centre, and then continue to pass forwards for
some distance : these canals also contain blood vessels.

In the centre of ribs about to ossify a distinct medullary
canal containing blood vessels in abundance is clearly per-
ceptible.

Vessels are also contained in the fatty masses enclosed in
some of the joints and called the glands of Havers ; from
these the adjacent cartilages doubtless imbibe a portion of
nutrient plasma.

Amongst fibro-cartilages the synch ondroses are stated to
receive vessels. Nerves have not, as yet, been discovered in
cartilages which may be irritated for any length of time
without the slightest pain being occasioned.

During ossification, between the cartilage to be converted
into bone and that which is to remain as the articular
cartilage, a layer of vessels passes which, as the ossification
advances, gradually retire and wholly disappear soon after
birth.

As cartilages do not contain vessels, they are not subject
to those disorders which depend upon errors of the circula-
tion ; that is, they are not liable to inflammation and its
consequences. Ulceration of cartilages is indeed described
by writers ; but this term is wanting in accuracy when
applied to the erosion of which cartilages are susceptible, and
which is effected not through any operation occurring in the
cartilage itself, but through the action of vessels which, pro-
ceeding from the synovial membrane, dip down into the car-
tilage, and occasion its partial absorption. For the same

CARTILAGES. 289

reason, cartilages do not readily become atrophied by pres-
sure : thus, when an aneurism destroys the bodies of the
vertebrae, the intervertebral cartilages are not at the same
time removed, but resist for a long period the continued com-
pression to which they are subject.

There is, however, one description of cartilage in which
blood vessels regularly appear, viz., cartilages of ossification,
in which may be included the costal and thyroid cartilages,
their presence proceeding and accompanying the process of
the formation of bone.

Cartilages, like all the extravascular tissues, imbibe fluid
readily : thus, when immersed in a coloured solution, they
assume the tint of the liquid in which they are placed. In
jaundice, according to Bichat *, they present a greenish yellow
tint, from the imbibition of a portion of the bile with which,
in this disorder, the system is so pregnant.

GROWTH AND DEVELOPMENT OF CARTILAGES.

Cartilages, as already observed, consist of cells imbedded in
a hyaline or fibrous base. In considering, then, the develop-
ment of cartilages, the growth of both the cells and the inter-
cellular substance must be discussed.

We will first describe the multiplication of cartilage cells.

The Cells. — Cartilage cells are multiplied in two ways.

1st. By the division of a single cell into two or more parts,
each of which becomes, when the separation is completely ef-
fected, a distinct cell. The reality of this method of increase
in the number of cells will become evident on the attentive
examination of almost any thin section of cartilage, in the
cells of which, but especially in those placed near the
natural border, the several stages of their division may be
clearly and satisfactorily recognised. (See Plate XXX.)

2nd. By the development of cytoblasts either in the
intercellular substance, or else in parent cells. This mode of
increase is a true reproduction, new cells being continually

* Anat. Gen. t.iii. p. 192.

290 THE SOLIDS.

formed and developed. The first process of multiplica-
tion is of a nature totally distinct from reproduction, for
although by it the cells are multiplied, no new ones are
developed. There is the same differences between the two
forms of cells, that having its origin in the division of a
single cell, and that developed from a cytoblast, as there is
between a slip and a seed. (See Plates XXX. and XXXI.)

The parent or primary cells filled with the second or even
the third generation of new cells, may be detected in
abundance in almost any cartilage, but especially in the in-
tervertebral cartilages. It is worthy of notice that the
parent cells are usually situated near the centre of each
cartilage, while the single cells, in which the process of di-
vision is best seen, are mostly found outside these. From
this arrangement we may infer that the deeper seated cells
are older than those of the circumference. Whether the
latter are derived from the former, or whether they are
formed on the external margin of the cartilage, it is not easy
to decide ; it is most probable, however, that from the cir-
cumstance that the parent cells are principally found in the
centre of the thicker cartilages, and that it is in this situa-
tion that ossification commences, that the second proposition
is the correct one.

It is a singular fact that the development of cartilage
cells may be as readily followed out in old cartilages as in
young, numbers of cells in process of division and in the
stage of parent cells being readily distinguished in each. As
after maturity cartilages do not undergo any increase in size
and as from the preceding observations it woulcl appear that
new cells are continually being evolved, it must be presumed
that the very old cells are absorbed and their place supplied by
the younger ones.

In the multiplication of cartilage cells by division, a corre-
spondence may be traced between cartilages and many of the
lower tribes of animals and vegetables, especially with the
majority of the alga3 ; and in the development of secondary
cells in parent cells, they exhibit a still closer analogy with
certain alga? of the genera Hcematococcus and Microcystis, the

CARTILAGES. 291

cells of some of the species of which it would be impossible
to distinguish from the isolated cartilage corpuscles of the
epiglottis and intervertebral cartilages,

In these methods of multiplication, cartilage cells would
appear almost to stand alone in the animal economy : thus it
is certain that the red blood corpuscles, epithelial cells, and
their various modifications into epidermis, nails, pigment
cells, and hairs, are not multiplied either by division or by
the development of secondary enclosed in primary or parent
cells.

The analogy existing between the cells of cartilages and
those of certain algse has been noticed by Dr. Carpenter in
the 3d edition of his " Principles of Human Physiology."

The Intercellular Substance. — Very young cartilages, and
also the smaller ones of adults are constituted almost entirely
of cells, with but little admixture of intercellular substance.
As, however, these young cartilages grow in size, the relative
amount of this substance increases, and the space between
the cells becomes greater.

The augmentation of the intercellular substance takes
place principally by a deposit of new layers on the exterior
surface during j;he period of the development of cartilages ;
this mode of increase is proved by their separation after long
continued maceration into distinct laminae.

A second mode of increase of the intercellular substance
has been stated to exist by Henle *, principally in the car-
tilages of ossification, and under no circumstances in the
fibro-cartilages, viz., by the thickening of the walls of the
cells which become confounded with or melted down into
the intercellular substance, the cavity in which the cells are
lodged being diminished, or this also augmenting at the same
time. The proofs adduced in favour of this method of in-
crease are not convincing.

Jt has already been stated that in the true cartilages which
are subject to ossification fibres appear; these fibres as well
as the analogous ones of fibro-cartilages, are probably of a

* An.it. Gen., vol. vii. p. 376.

292 THE SOLIDS.

nature wholly distinct from those of ordinary cellular tissue,
and which have their origin in cells ; under no circumstance
can either cells or nuclei be discovered in the fibres of carti-
lages.

Cartilage is not capable of regeneration: when it has
been fractured, the union of the surfaces is very incom-
plete, and principally by means of cellular tissue.

The formation of cartilage almost invariably precedes the
development of bone, of which we shall shortly have to
speak more particularly in the Chapter on Bone.

Masses of cartilage are also occasionally produced upon
the external surface of the syno vial membrane of joints ; these
are at first peduncated, but at length cease to have any con-
nexion with the organization, and move freely about in
the cavity of the joints.

Occasionally, though rarely, cartilage is developed in the
cellular tissue of glands, forming a solid tumour, which was
first described by Miiller under the name of Enchondroma,
and of which I recently had the pleasure of receiving a very
excellent example from Dr. Letheby.

USES OF CARTILAGES.

The uses of cartilages are of a mechanical nature, depend-
ing upon certain physical properties.

Thus we find them to be situated in localities, where
solidity is required in combination with flexibility and
elasticity.

In the larynx, the flexibility and elasticity of cartilages
assists in the modulation of the voice.

In the nose, so liable to injury, their flexibility often
allows this organ to sustain severe blows without detriment.

The articular cartilages protect the bones from injury to
which they would be otherwise so subject in the sudden and
violent exertions of the body, as in jumping on account of
their solid and unyielding nature.

CAET1LAGES. 293

The intervertebral cartilages are exceedingly elastic and
flexible, and permit the free movement of the spinal column
in almost any direction, and which is so necessary in the
execution of the various motions of the body.

The articulations united by synchondrosis, as that of the
pubis, are remarkable for their strength, although at the same
time it admits a slight degree of extension and compression.

Lastly, the epiglottis is enabled to preserve the erect posi-
tion so essential to the maintenance of life in consequence of
its exceeding elasticity.

294 THE SOLIDS.

ART. XV. BONE.

THE next tissue to be considered is the osseous.

Bones are divided after their form into long, flat, and
irregular : long bones consist of a body or shaft termed
diaphysis, hollowed out in the centre into the medullary
canal, and of two extremities called Epiphyses, and which
in early life are distinct from the shaft; each long bone,
moreover, is made up of two modifications of bony structure,
the cancellous and the tabular ; the former is loose and
reticular, the latter hard and compact : of the one, the great
bulk of the epiphyses are constituted; of the other, the
diaphysis is chiefly formed : in flat and irregular bones, the
medullary canal is wanting ; the first consist of an inner and
outer table of compact bony tissue, enclosing a thin plate of
cancellous structure, termed Diploce, and the latter are com-
posed principally of cancelli, enclosed in thin and irregular
osseous laminae.

STRUCTURE OF BONES.

The two elements into which all bones resolve themselves
are osseous corpuscles and lamina ; the latter, according to
the plan of their arrangement and development, give rise
to the cancelli, medullary canals, and plates of which bones
are constituted.

Cancellous Structure.

The cancellous structure of bone is made up of thin and
inosculating plates of bony matter, which enclose spaces
between them, and all of which freely communicate with
each other : these spaces are called medullary cells. Each
plate is also compounded of several lamina, in the intervals
between which a few bone corpuscles exist.

BONE. 296

The fact of the free communication of the medullary cells
is proved by the two following experiments : —

Thus, when mercury is poured into a hole made in the
extremity of a long bone, or on the surface of a flat or
short one, it will traverse all the medullary cells, and escape
by the apertures which exist naturally on the exterior of
bones.

Again, if a bone be cut through at one of its extremities,
the natural openings on its surface being at the same time
closed, and if then the bone be exposed to the action of
heat, all the marrow will escape slowly by the cut ex-
tremity. *

The spaces described by the medullary cells are irregular
in size and form, those which are first developed being
smaller than those of older formation (see Plate XXXIV.
Jig. 3, 4.) : they are usually of an elongated shape, their long
axes being parallel to that of the bone itself: when viewed
transversely, they are seen to be more or less rounded, but
irregular in outline : it is in the transverse sections that the
bone cells and lamellae are best seen.

Medullary cells in the recent state are filled with fat
vesicles, with blood-vessels, and with granular nucleated cells
analogous to those of epithelium : these last occur in con-
siderable quantities in the cancelli, and especially in those of
foetal bones, in which the fat vesicles are for the most part
absent. (See Plate XXX. fig. 4.)

They inosculate freely with the medullary canals situated
in the outer and compact plates of bone.

Canalicular Structure.

The compact tissue of bones is traversed by canals, which
have been termed medullary from the fact of their being in
communication in the long bones with the great central
medullary cavity, and from the circumstance of their being

* Bichat, Anatomic Generate, t. 111. p. 25.
B B

296 THE SOLIDS.

partly occupied with medullary matter. They are also called
Haversian, after their discoverer.

These canals are situated between the laminse of which
bone is composed, and take a course in the long bones, in
which they are best seen, parallel to their axes, being also
joined together by short transverse branches : they thus form
a network of tubes analogous to that exhibited by the
minute vessels which they convey and protect ; the form
and sizes of the meshes vary : in the long bones they are
elongated. (See Plate XXXII. fg. 4.)

They communicate, in the long bones, with the medullary
cavity, dilating into cells or vesicles, from which a short tube
proceeds previous to their entrance into it ; they also open
upon the external surface of all bones by somewhat expanded
apertures, and inosculate freely with the medullary cells.

Medullary canals are not all of equal diameter through-
out the compact tissue of a bone ; those situated between the
external plates are two or three times smaller than those
which are placed more internally. (See Plate XXXII.

fig- 1.)

In a transverse section the canals are seen to be either
circular, oval, or rarely angular.

In the flat bones the course of the medullary canals is more
irregular than in the long bones ; in the parietal bones they
proceed diverging from the parietal protuberance towards
the margins of the bone ; and in the frontal from the supra
orbitar ridge towards the coronal suture.

In the long bones, near their extremities and in the vicinity
of the articular cartilage, these canals end in blind or caecal
extremities, a single canal passing up into each of the promi-
nences, into a number of which the articular surface of bone
is elevated.

It is these canals which impart the striated structure pre-
sented by bone, and which is visible to the unassisted eye ;
in longitudinal sections they are frequently cut through, and
their cavities exposed.

The contents of medullary canals are similar to those of
the medullary cells, of which they are to be regarded as a

BONE. 297

modification, there being an insensible transition from the
one to the other.

Drs. Todd and Bowman recognise two forms of Haversian
canals, one of which carries veins, the other arteries, a
single vessel being distributed to each; those canals which
contain the veins are stated to be larger than those which
convey the arteries, and to be dilated into a pouch or sinus
at the situation where two or more canals unite to form a
single larger tube.

Lamella.

The more essential constituents of tnie and fully developed
bone are, as already observed, lamella and bone cells; the
medullary cells and canals just described are merely definite
spaces existing between the lamellae, the arrangement and
ultimate structure of which we shall in the next place pro-
ceed to notice.

It is principally by the successive development of new
Iamella3 that bones increase in diameter ; these are usually
deposited in the direction of the axis of the bone ; if, there-
fore, a transverse section of a long bone be made and examined
with the microscope, the lamellae will be seen to be arranged
as follows : first, several layers will be observed to pass entirely
round the bone, secondly, others will be noticed encircling
each Haversian canal, and lastly, irregular and incomplete
lamellae occupy the angular spaces intervening between the
sets of lamellae concentrically disposed around each canal.
(See Plate XXXII. figs. 1, 2, 3.)

The number of layers which pass interruptedly around
the bone are not very numerous, being generally less than
twelve ; the amount of those which encircle each Haversian
canal varies from two or three to upwards of twelve, the
smallest number of lamellae usually appertaining to the
smallest canal. (See Plate XXXII. fig. 1.)

Examined with an object-glass of the fourth of an inch
focus the lamella, after the separation of its earthy matter

B B 2

298 THE SOLIDS.

by means of dilute hydrochloric acid, exhibits a delicate
structure, the precise nature of which it is not easy to deter-
mine ; its surface will be seen to be marked out into innumer-
able lozenge-shaped spaces, one side of each of which is
concealed by a dark shadow, and the divisions between which
are without shadow. (See Plate XXXIII. fig. 4.)

This interesting structure was first distinctly pointed out
by Dr. Sharpey *, who conceives that it arises from the cross-
ing and union of fibres ; these, however, cannot be traced out
and displayed as separate fibres, owing, it is presumed, to
their being united or fused together at the points where they
cross each other ; it sometimes happens, however, that at the
torn edge of a lamella a short projecting process may be
seen which presents much the aspect of a true fibre, f

The appearance presented by a lamella thus figured might
be compared to the engine-turned case of a watch, and it
might also be conceived that it was produced by the union
of a number of diamond-shaped cells, and not by the crossing
of fibres.

One argument in favour of the fibrous constitution of the
lamellae may be derived from the fact that the cancelli of
bone in process of development clearly exhibit a fibrous struc-
ture.

Cross sections of the lamellae may also sometimes be ob-
served to be marked with short and radiating lines, which
most probably depend upon the structure already noticed.

The osseous lamellae are likewise perforated necessarily
with numerous minute apertures occasioned by the canaliculi
of the bone cells, and which when seen with a low power

* Quain's Anatomy, 5th edition, part ii. p. cxlii.

f It would appear to be probable from the following quotation that
Henle had seen the structure above described. " The lamellae examined
on their flat side have appeared to me to be generally hyaline or finely
dotted, but sometimes also fibrous ; the fibres are either pale and as
though composed of grains, or obscure and rugged ; one never succeeds
in isolating them for a certain space, because they are branched, inter-
woven, and in a word perfectly identical with the fibres of fibro-
cartilages."

BONE. 299

appear like so many small dots ; they contain also, scattered
throughout their substance, multitudes of granules of earthy
matter.

The only really necessary constituents of bone would appear
to be the cellular tissue and earthy matter. The combination
of these two forms bone in its simplest condition. The me-
dullary cells, Haversian canals, and bone cells, are connected
only with the growth and nutrition of bone and occur seldom,
except where the size of the bony formation renders their
presence necessary for its growth and support.

Bone Cells.

Distributed throughout the cancellous and the compact
portions of bone, cells of a peculiar structure occur in con-
siderable quantities.

Concerning the nature of these cells much difference of
opinion prevails ; by some they are described as mere vacuities
existing in the tissue of the bone, by others as hollow cells,
as nuclei of cells, and as true nucleated corpuscles. That
the bone cells take their origin in nucleated cells cannot
be doubted.

The circumstances which have given rise to the notion of
their being mere vacancies or lacunas are the passage of
fluids through them, their infiltration with solid matter, and
the optical appearances sometimes presented by them. All
these circumstances admit, however, of explanation on the
supposition of their corpuscular origin.

That they are derived from granular cells may be proved,
it seems to me, by the study of the development of bone,
they being in growing bones first traceable as nucleated cor-
puscles, a condition to which they may be again reduced in
an adult bone by the removal of the earthy matter. This
appearance is best seen in the large bone cells of the Siren,
Proteus, or Menobranchus. •

The bone cells, which are very numerous, are situated be-

B B 3

300 THE SOLIDS.

tween the osseous laminae already described, and by which
they are compressed ; they thus present in all sections of
bone an elongated or flattened form, and in transverse cut-
tings those facing the Haversian canals appear not merely
elongated, but also slightly curved, the concavity of the arc
being directed inwards towards the canals, and the convexity
outwards in the contrary direction. (See Plate XXXII.

figs, i, 2.)

When viewed as transparent objects they appear black,
and when as opaque they are of a pearly whiteness.

From the margins of each bone cell proceed a number of
branched canals, which, passing through the lamellae situated
on either side of the cell, inosculate freely with the canaliculi
given off by the bone cells of the contiguous lamellae (see
Plate XXXII. fig. 3.) ; this process of inosculation being
frequently repeated between the cells of each lamella, a com-
munication is thus established between the medullary cavity
on which the canaliculi of the first series of cells opens, the
Haversian canals, and the external surface of the bone. The
reality of this communication may be attested by applying a
drop of oil of turpentine to a section of dry bone placed be-
neath the microscope, when the passage of the fluid through
the bone cells may be followed with the eye. This experi-
ment was first suggested by Drs. Todd and Bowman.

The canaliculi of bone cells treated with acid usually dis-
appear, the body of the cell alone remaining.

The size of the bone cell throughout the whole of osseous
vertebrate series, stands in relation to that of the red blood
disc; and Mr. Quekett, who has instituted an inquiry into their
form and size in a great variety of animals, has arrived at the
conclusion that the class to which any animal belongs, whe-
ther that of Beasts, Birds, Reptiles, or Fishes, may be deter-
mined by the two particulars referred to. This discovery is
likely to be especially useful in the determination of the true
position in the animal series of many fossil bones, which but
for.it would have continued to be enveloped in uncertainty
and conjecture.

In many osseous fishes the bone cells appear to be wanting,

BONE. 301

they having merged into canaliculi, which are often of con-
siderable size.

Marrow of Bones.

The medullary cavity of adult long bones, the medullary
cells, and the larger medullary canals, all contain a loose cel-
lular tissue, in the meshes of which a greater or less amount
of marrow or fat cells is enclosed. (See Plate XXX. Jigs.
3,4.)

In foetal and very young bones the fat vesicles are wanting

in the three situations named, the place of fat being supplied

by immense numbers of the small granular nucleated cells,

which have already been referred to. (See Plate XXXIII.

Jig. 5.)

It has been stated that the medullary cavity, cells, and
canals all communicate freely ; the marrow therefore and its
enclosing cellular tissue are everywhere continuous.

Periosteum.

The external surface of all bones, with the exception of
their articular extremities, is covered with a dense membrane
composed of fibrous tissue, which is very rich in blood-vessels,
and which is called the periosteum.

The internal surface of the medullary cavity, cells, and
larger Haversian canals, is also lined by a vascular membrane
much more delicate in structure, which may be regarded as
an internal periosteum.

It is by means of the vessels which ramify through these
membranes that the nourishment of the bone is secured.

Vessels of Bone.

Bones are richly supplied with blood-vessels, which pene-
trate every part of their structure.

Thus externally, branches, principally arterial, proceed from
the periosteum, enter the numerous apertures of the Haver-

302 THE ' SOLIDS.

sian canals, and ramifying through these form a capillary
network ; these external periosteal vessels may be seen with
the unaided eye extending into the bone like so many fine
threads on the cautious detachment of the periosteum.

Again, in the long bones, a large artery penetrates by an
oblique canal situated at the junction of their upper and
middle thirds, into the medullary cavity, and sends branches
upwards and downwards, which ramify on the membrane of
the medulla or internal periosteum, some of these proceed
onwards into the medullary cells, and others inosculate with
the capillaries of the Haversian canals already referred to.

The flat and irregular bones are furnished not with a
single vessel of large calibre, but with several of smaller size.

These larger arteries are accompanied by veins, whereby a
portion of the venous blood is returned from the bone.

Breschet *, moreover, has described in the flat bones, and
especially in those of the cranium, a system of osseous canals,
which contain only veins, and which are furnished with valves,
which is not the case with the other veins of bones.

The walls of these canals, which ramify after the manner
of vessels, are pierced with apertures, by which they receive
small capillaries : they traverse principally the spongy por-
tion of bones, afterwards they pass through the compact part,
and finally terminate on the external surface of the bone.

These canals are best seen in the flat bones of the cranium,
which should be dried, and the outer table of compact sub-
stance removed.

Lymphatics have been observed in some few instances in
bone.

Nerves of Bone.

Nerves have not hitherto been satisfactorily traced into
bones ; nevertheless, the great pain experienced in diseased
conditions of them proves incontestably the existence of ner-
vous fibrillae.

* N. A. N. C. xxiii. P. i. p. 361. ; Recherches Anat. Physiolog. et Pat.
sur le Systeme Veineux, Paris, 1829. fol.

BONE. 303

GROWTH AND DEVELOPMENT OF BONE.

Growth of Bone. — The situations in which the chief
increase of bone occurs are commonly stated to have been
accurately determined by means of the different madder
experiments instituted by numerous observers.

If an animal be fed for a short time with the root of
madder, its bones will become tinged with the colouring
matter of that plant, between which and the phosphate of
lime of the bone a great affinity exists.

On a close examination of sections of a growing long bone
it will be observed, however, that the tissue of the bone is
not uniformly coloured, but that in a transverse cutting the
colour is principally situated in the outer part. The same
fact is shown also in longitudinal sections, which, however,
if they embrace the entire length of the bone, will also be
observed to be tinged with the colouring matter towards
either extremity.

Again, if a magnifying glass be applied to a thin trans-
verse section of the growing bone of an animal fed upon
madder, each Haversian canal will be seen to be surrounded
by its ring of colour. For this beautiful illustration of the
effects of madder we are indebted to Mr. Tomes. (Plate
XXXIII. fig. 6.)

These several observations have been presumed to prove
that bones increase in length principally by additions of new
matter to their extremities, and in breadth by the deposition
of new laminae of bone on their outer surface, as well as by
the formation of fresh lamellae in each Haversian canal, which
last grow and expand in size simultaneously with the laminae
placed external to them after their first formation.

Now, although it is very probable that bones increase
in diameter to a great extent by the addition of new matter
on the external surface, and although it is quite certain that
they become elongated by the formation of bony matter at
their extremities, it appears to be most clear that we are not
justified in coming to any such conclusion from the results of
the experiments with madder. All that these celebrated

304 THE SOLIDS.

experiments really seem to prove is, that bones in contact with
blood-vessels containing the colouring matter of madder readily
imbibe and retain that principle in common with the liquor
sanguinis.

The bones of old animals are coloured with much more
difficulty than those of young ; a few hours in very young
animals being sufficient to ensure their colouration.

Development of Bone. — We come now to consider the
exact process of the development of bone.

Bone is developed either in membrane or in cartilage ;
when in the former it may be termed intra-membranous, and
when in the latter mtra-cartilagmous ossification.

Infra-membranous Form of Ossification. — We will con-
sider, first, the intra-membranous form of ossification. Dr.
Nesbitt * was the first to distinguish between the two types
of ossification. More recently Dr. Sharpey f has described
clearly and satisfactorily the steps of the intra-membran-
ous development. This form he considers to belong to
certain flat bones of the cranium, as the parietal and por-
tions of the frontal and occipital bones, as well as to the
outer surfaces of the long bones.

The first perceptible ossification of the parietal bone,
which may be selected as one of the best examples of this
form of osseous development, consists of a network of
spiculae of bone, the outermost of which radiate in lines to-
wards the circumference, and are connected by short trans-
verse branches. (See Plate XXXIII. figs. 1, 2.)

As the ossification proceeds, the first-formed spiculse, in
the centre of the bone, become greatly increased in thickness,
and the spaces between them much diminished in size ; the
ossification continues thus to spread and consolidate until the
parietal meets the neighbouring bone, with which it is at
length united by suture.

If, however, the microscope be brought to bear upon one of
the newly-formed spiculae before the entire bone has attained

* Human Osteogony, Lond. 1736.

t Dr. Quain's Anatomy, edited by Mr. Quain and Dr. Sharpey, 5th
edition.

BONE. 305

any considerable development, it will be seen that the ossific
deposit takes place in the fibres of fibro-cellular tissue, inter-
mingled with which numerous granular and nucleated cells
occur ; these fibres, which are disposed in bundles, invariably
precede the deposition of bony matter, and mark out the
course of the future spiculse. (See Plate XXXIII. Jig. 3.)

The granular cells just noticed have been observed by Dr.
Sharpey, who remarks upon their distribution in the direc-
tion of the future spiculse, and who considers that they are
connected in some way or other with the process of ossifica-
tion.

There can scarcely be a question but that they are the
bone cells in a rudimentary state, their conversion into
which it is not difficult to trace.

Now it does not appear that cartilage is at all concerned
in any one stage of the development of the parietal bone of
the human embryo. In that of the sheep and some other
animals a lamina of cartilage is present in connection with
the parietal bone ; but this takes no part in the process of
ossification, but merely serves as a support to the newly-
developed bone, and extends beneath the first-formed portion
of it alone.

As the ossification advances still further, the interstices
between the first-formed spiculae become filled up, grooves
appear on the surface of the bone ; these radiate from the
centre towards the circumference, and ultimately become
converted into canals, which, being lined with a number of
concentric laminae, at length constitute complete Haversian
canals. The bone is then completely formed.

Intra-cartilaginous Ossification. — It has until recently
been supposed that the formation of bone always takes place
in cartilage ; this notion, as we have seen, is erroneous.

Ossification is also usually described as the conversion of
cartilage into bone ; this idea will be presently shown to be
equally erroneous, and the fact demonstrated that the intra-
cariilaginous ossification does not differ essentially from the
mtra-membranous form.

If the microscope be brought to bear upon a thin longitu-

306 THE SOLIDS.

dinal section of an ossifying foetal bone, in connexion with
its cartilaginous epiphysis, the following particulars will be
noticed.

First, it will be observed that the cartilage cells in the
neighbourhood of the bone, instead of being scattered irre-
gularly throughout the intercellular substance, are arranged
in several consecutive and alternating rows or files, the
lowermost of which dip into and are surrounded by osseous
cups and septa ; that the cells forming the lower portion of
the lowest tier are larger, and less compressed, than those
which enter into the formation of the upper part of each
lower series, and that they are separated from each other
by distinct portions of intercellular substance. Secondly,
it will be remarked that the extremities of the still soft
bony spiculse invade and extend into the spaces which in-
tervene not merely between the rows of cells, but also
between the individual cells, and further that granular and
probably cytoblastemic particles are deposited in this inter-
cellular substance, particularly where this comes into con-
tact with the cartilage cells themselves. (See Plate XXXIV.

fg*> i- 4.)

As the process of ossification advances, the cell wall of
the cartilage cells becomes absorbed; granular corpuscles
are next generated in the primary cancellus, after which the
nuclei of the cartilage cells (which are observed to become
smaller the deeper they lie in the bone), are removed
by absorption ; finally, the small septa intervening between
the individual cartilage cells are removed, the larger me-
dullary spaces being thus formed. (See Plate XXXIV.

fig- 4.)

Furthermore, in these precursory and even in the older
spiculse, fibres analogous to those in which the spiculae
of the parietal bones are developed may be abundantly
detected.

Such is a brief sketch of the several steps of the intra-
cartilaginous form of ossification.

Now the process which we have just described is con-
stantly in progress ; cartilage cells on the one side are con-

BONE. 307

tinually being developed in the epiphysis ; they are also
constantly marshalling themselves into rows or columns,
the lowermost cells of which dip into the cancelli and be-
come absorbed ; on the other side the cancelli of the bone
are continually invading the intercellular spaces of the
cartilage.

It is thus that a bone grows in length. Each epiphysis
of a long bone, however, after a time becomes a centre of
ossification ; this proceeds to meet that of the shaft ; a layer
of cartilage usually, however, intervenes between the two,
until the period of the full development of the osseous
system, when this layer becomes absorbed, and the shaft and
the epiphysis become consolidated by bony union. The first
trace of ossification of the epiphysis in the human subject
is usually apparent at about the ninth month.

We have now to ask ourselves the question, how does
the bone increase in diameter ? We have shown that it is
generally considered as proved by the madder experiments
already referred to, that a long bone increases in breadth by
the deposition of new lamellae at the circumference, as well
as in the cavities of the medullary cells and Haversian
canals ; but we have seen also from what has been already
said in reference to the different sizes of the external and
internal Haversian canals and their mode of formation, that
each of these canals is continually undergoing a process of
expansion, and it is by this expansion that the chief increase
of the diameter of a bone takes place. It was formerly sup-
posed that a layer of cartilage existed in all growing bones on
their external surfaces, but we now know that such is not
the case, and that the new osseous deposit takes place in
fibres. If it were necessary that a layer of cartilage should
exist in the situation named, it would be equally requisite
that it should be present in each medullary cell and in each
Haversian canal.

The small granular corpuscles already referred to as
occurring in the cancelli of all bones, but especially in those
of the fostus, it would thus appear are developed in con-
siderable quantities at a very early period of the develop-

308 THE SOLIDS.

ment of bone ; they are generally apparent in the third or
fourth tier of the first formed and small cancelli, and while
the nuclei of the cartilage cells yet exist. (See Plate
XXXV. fig. 3.)

It will now be perceived that the intra-cartilaginous form
of ossification is identical with the intra-membranous type
in all essential particulars.

It will also readily be seen, that this view of the process
of ossification differs very considerably from the more re
cently expressed opinions on the subject ; those, for example,
of Drs. Todd and Bowman, and of Mr. Tomes.

The authors of the " Physiological Anatomy" consider that
the nuclei of the cartilage cells become developed ultimately
into the bone celle.

There are many considerations which would lead to the
conclusion that such a transformation is but little probable,
the following of which may be referred to : —

The formation of bone independent of cartilage, as in the
intra-membranous type of ossification.

The small number of the cartilage cells compared with the
vast quantities of bone cells which exist in even a young
bone.

The impossibility of explaining why the permanent car-
tilages should not, like the temporary, be constantly sub-
ject to ossification, since they are both organised in precisely
the same manner.

The proof that cartilage cells have no further stage of
development to pass through, manifested by the fact of the
occurrence of parent cells in all cartilages, whether temporary
or permanent.

The chief new points contained in Mr. Tomes's views * are
the ossification of the walls of the several cartilage cells
which form each roll or column, and the conversion of a
number of these, by the absorption of the contiguous walls of
the cells, into a single cavity or tube, which becomes filled with
a granular blastema ; this tube Mr. T. considers to be an

* See Art. Osseous Tissue, Cyclop, of Anatomy and Physiology.

BONE. 309

Haversian canal, and its wall to constitute ultimately the
outer lamina of such canal.

The arguments adduced in disproof of the opinion that the
nuclei of the cartilage cells become converted into bone cor-
puscles, apply with equal force against the idea of the calcifi-
cation of the walls of the cartilage cells.

Bone Cells. — Bone cells, then, according to the views of
the author, are not transformed nuclei of cartilage corpuscles,
but take their origin in distinct granular cells, which may be
clearly seen in the growing spiculae of bone dispersed amongst
the fibres in which the earthy matter of bone is first deposited,
and which at length become entirely imbedded in the earthy
deposition.

As, however, it is most probable that a development of
bone cells and new laminaa of bone are ever in progress even
in adult bones, we should expect to encounter in the cancelli of
bones of every age fibres of cellular tissue and granular cells ;
both these do occur in them, and especially the latter, which
are met with in great numbers.

These granular nucleated cells are more numerous in foetal
and young bones^than in those of older formation ; in the
former, indeed, they almost entirely fill up the cavities of the
cancelli : in the latter, although they are still numerous, their
place is supplied with fat vesicles, which are not present in
the former.

It seems to me to be not improbable that two kinds of
granular cells may exist in the medullary spaces, &c., one
consisting of rudimentary bone cells, and the other connected
with the elaboration of the marrow, which occupies the me-
dullary cavity, medullary cells, and larger Haversian canals.

It might be supposed that these granular cells were the
white corpuscles of the blood escaped from the ruptured
vessels, the red blood discs having been absorbed ; this no-
tion is, however, disproved by the fact that many of them
are much larger than the colourless corpuscles of the blood.
(See Plate XXXIII. fig. 5.)

The existence of a granular blastema in the cancelli, &c.

310 THE SOLIDS.

of bones was first observed by Drs. Todd and Bowman*,
who considered that it was concerned in the development of
blood-vessels.

Presuming it to be proved that the bone cells are derived
from true corpuscles, we have yet to decide whether we are
to believe with Schwann f> that they are complete cells, and
that the canaliculi are prolongations of the walls of these
cells ; that, in fact, they possess a structure conformable with
that of the stellate pigment cells of the skin of the frog, or
of the lamina fusca of the eye ; whether we are to consider
with Gerber J, Bruns §, and E. H. Mayer ||, that they are the
nuclei of primitive elementary cells and that the canaliculi are
prolongations of these ; whether, again, we are to regard them
with HenlelT as the cavities of cells, the walls of which have
become thickened, and the canaliculi of which proceed from
the central cavity through the thickened walls of the cells, as
do the porous canals of many vegetable cells ; lastly, whether
we are to believe, with Todd and Bowman, that the canaliculi
proceed from the nucleus, which afterwards becomes absorbed,
and that thus the lacuna is left.

That the first view is the correct one, and that the bone
cells are to be regarded as complete corpuscles, the canaliculi
of which are formed by the extension of the cell wall, is, I
think, proved by watching the formation and development of
bone cells in growing spiculaB and by the action of dilute
hydrochloric acid, which, by removing the earthy matter,
allows the granular texture, which originally characterised
them, to be again seen.

The last points left for consideration in reference to the
development of bone are, the modes of formation of the
medullary cavity, medullary cells, and Haversian canals.

Formation of medullary Cavity. — Traversing the sub-
stance of each cartilaginous epiphysis, a number of large and

* Physiological Anatomy, Chap. 5.

f Mikroskopische Untersuchungen, pp. 35. 115.

| Allgemeine Anatomie, p. 104.

§ Ibid. pp. 240. 252.

|| Muller, Archiv. 1841, p. 210. ^[ Anat. Gen. t. vii, p. 409.

BONE. 311

branched canals may be seen in both transverse and longitu-
dinal sections. (See Plate XXXV. figs. 1, 2.)

The majority of these proceed directly from the ossified
part of the shaft in connection with the epiphysis ; in this
situation they are of larger size, and are also fewer in number,
than they are higher up in the epiphysis, not exceeding
usually five or six, but becoming multiplied, by the giving
off of branches, to as many as fourteen or sixteen ; others,
however, enter the epiphysis from the sides, near the junction
of the bone and cartilage.

The interior of these canals is occupied with blood-vessels
and with granular nucleated cells, precisely like those ex-
isting in the medullary cells of bone. (See Plate XXXV.

fig. 3.)

The cartilage cells in a transverse section of the canals im-
mediately surrounding their orifices are disposed in a rayed
manner.

Having thus described the structure, contents, and distri-
bution of these canals, we will next inquire their use. ( See
Plate XXX V.fig. 3.)

If a number of transverse sections be made not merely of
the cartilaginous epiphysis, but also of the bone in connection
with it, and if these be examined in the order of their re-
moval, it will be observed, first, that in those sections which
are made from the cartilaginous epiphysis most removed
from the bone, the apertures of these canals are small and
numerous (see Plate XXXV. fig. 1); second, that in the
sections taken from the proximal end of the epiphysis the
canals are fewer in number and their orifices larger (sec
Plate XXXV.) ; thirdly, that in other slices, which include
a portiorn of both catilage and bone, the latter always com-
mences on the circumference of the section, proceeding
gradually inwards, the portion of cartilage surrounding the
canals in question being the last to become ossified (see
Plate, XXX V. figs. 2,3.); fourthly, in cuttings made below
the cartilage and through the bone, spaces four or five in
number, filled with granular cells corresponding in situation
with the afore-described canals, will be observed ; fifthly, in

c c

312 THE SOLIDS.

Others carried still deeper into the bone, these several
apertures will have coalesced into one large space — the rudi-
mentary medullary cavity.

From these several particulars, I therefore infer that the
canals in question are intimately connected with the form-
ation of the medullary cavity ; and that the absorption of the
cancelli situated between each of them is brought about by
the vessels contained within them, aided also probably by the
granular cells.

Were the canals merely destined to convey to the cartilage
the nourishment necessary for its transformation into bone,
it might be expected that they would serve as so many centres
from which the ossification would proceed ; we have seen,
however, that the cartilage in their immediate vicinity is the
last to be removed, and its place supplied by bony cancelli.

Medullary cells. — The primary cancelli are small, studded
with granules, form closed cavities, and do not contain bone
cells. (See Plate XXXIV. Jigs. 2, 3.) The secondary and
larger cancelli are formed by the absorption of the numerous
septa of the primary cancelli ; they do not form closed cavities,
but communicate freely together and contain bone cells im-
bedded in their parietes. (See Plate XXXI Y./^. 4.)

Haver sian canals. — The Haversian canals are generally de-
scribed as being formed by the filling up of certain of the me-
dullary cells, in consequence of the successive deposition of
new lamina? of bony matter. It seems to me, however, to be
very questionable, whether they are ever formed in the manner
indicated, and if so, such is assuredly not the general mode
of their formation.

I am induced to take a different view of their formation,
and consider they originate as follows : —

The surface of all bones, whether long, flat, or irregular,
is observed to be marked with numerous grooves of different
sizes and depths. In the recent state these are occupied with
blood-vessels, and it is around them that successive layers of
bone are deposited, until at length the vessels become en-
tirely included and a perfect canal is formed.

In transverse sections of long bones, grooves and partially

BONE, 313

developed canals may generally be seen along the outer mar-
gin of the cutting.

This view of the formation of the Haversian canals also
accords well with other characters presented by transverse
sections of bone. Thus, in all such, it will be seen that the
smallest Haversian canals are situated in the external part,
while the larger canals are placed internal to these : it will
also be observed, that the smaller canals are surrounded by
the fewest number of concentric lamellae, and the larger by
the greatest number. (See Plate XXXII. fig. 1.) Now
the fact of an additional number of lamella encircling the
larger canals proves two things : first, that these large Haver-
sian channels are of older formation than the small ; and
second, that each lamella grows or expands after its depo-
sition, whereby the calibre of such canals becomes increased,
which is contrary to the generally entertained notion of the
formation of the Haversian canals, viz. by the filling up of
the large cancelli, brought about by the continual deposition
of new osseous lamellae, 'the outermost of which, for such a
result to ensue, must remain stationary in point of size.

ACCIDENTAL OSSIFICATION.

The abnormal growth and development of bone is a very
common pathological occurrence. Thus we have it occurring
on the surface of the bones themselves in the form of exostoses,
in the permanent cartilages, in the cellular tissue of muscles,
glands, the ovaries, membranes, as the coats of the arteries,
and probably occasionally also in that of every other tissue and
organ of the body.

It is not, however, every ossific deposit which presents
all the characters of bone : thus those contained in the ovaries,
in the mesenteric glands, and in the coats of the arteries,
usually want the more conspicuous elements of bone, the bone
cells and lamella?, although these have been met with in ossific
depositions remote from all connexion with bone.

In the reparation of fractures we have a development of
true bone preceded by the formation of cartilage.

c c 2

314 THE SOLIDS.

ART. 16. THE TEETH.

THE tissue of the teeth is to be regarded rather as a modification
of the osseous than as a distinct type of structure : the truth
of this remark is especially apparent on an examination of
two of the three substances which enter into the formation of
each tooth, viz. the cementum and dentine; the third con-
stituent, the enamel, is more nearly related in its organi-
sation to the epithelium, of which indeed it is a condition.

Each tooth consists of two parts : the body or crown, and
the root or fang ; the limits of these are indicated by a slight
contraction called the neck ; the crown is either simple or
divided, and the same is the case with root also : those teeth
which have a simple crown are called incisors and canines,
those with a double crown bicuspids, and those with the crown
quadruply divided molars. Again, the substance of each
tooth is divisible into three portions, each of which presents
characteristic differences ; these have received the names of
dentine, cementum, and enamel.

The dentine, also called the ivory, forms the chief bulk of
the tooth, occupies a central position, and its interior contains
the pulp cavity.

The enamel forms a layer of compact substance which
immediately surrounds that portion of the dentine of which
the crown of the tooth is made up.

The cementum, also called crusta petrosa, has a distribution
the very reverse of the enamel, and extends principally around
the fangs of the teeth, and terminates at the neck of the tooth,
in fact, just where the enamel commences.

STRUCTURE OF THE TEETH.

Having thus sketched the general position of the three
constituents of the teeth, the consideration of tke intimate
structure of each may next be entered upon.

TEETH. 315

Dentine. — The dentine is constituted of numerous tubes
imbedded in an intertubular substance; these tubes commence
at the pulp cavity, on the surface of which they open, and
from which they proceed in a radiate manner, terminating
on the borders of the dentine ; those arising from the upper
part of this cavity ascend almost vertically, those from the
sides more obliquely, and those from the lower portion pass
either horizontally outwards, or else descend somewhat.

These tubes diminish in size from their commencement to
their termination : they are branched ; at first they divide in
a dichotomous manner ; their subsequent ramifications are
numerous, minute and arborescent, and they inosculate freely
with the similar branches proceeding from the adjacent tubes :
those tubes which proceed towards the cementum are remark-
able for the very great number of branches into which they
divide.

The tubes of the dentine in their passage outwards do not
run in straight lines, but describe in their transit two or
three large curves, and each of these primary curves, when
examined with a higher power of the microscope, will be ob-
served to be made up of numerous smaller and secondary
curves ; both the large and small curvatures of one tube corre-
spond with those of another.

Such is the usual course and distribution of the tubes of
the dentine : several modifications of them, however, still re-
main to be noticed.

Thus sometimes a tube in its passage will dilate into a
bone cell, and again proceed onwards to its destination as a
tube ; at others a number of them, even in the centre of the
dentine, will break up and form a cluster of bone cells ; again
at others the tubes frequently become transformed into or
terminate on the margin of the dentine in bone cells. This
gradual transformation of the dentinal tubes into bone cor-
puscles, and their termination in the same, is especially seen
in tha.t portion of the dentine contiguous to the cementum.

The usual method of termination of the dentinal tubes, is in
fine and inosculating branches on the surface of the dentine.
Sometimes, however, the tubes anastomose in a peculiar

c c 3

316 THE SOLIDS.

manner and form distinct loops, at others the terminal
branches pass out of the dentinal substance, and extend either
into the cementum or the enamel ; this extension into the
former is a very frequent occurrence.

For illustrations of these several modifications, the majority
of which have been pointed out by Mr. Tomes in his excellent
lectures *, see the figures.

The surface of the dentine presents many elevations and
depressions : to these the enamel is accurately adapted ; it
also exhibits the hexagonal impressions of the enamel fibres.

The substance of the dentine is seen also occasionally to
be traversed with canals for blood-vessels, analogous to the
Haversian canals of bone.

The pulp cavity of the teeth _of old persons frequently be-
comes filled up, and even obliterated, by a secondary formation
of dentinal substance, and which may be called the secondary
dentine. This dentine results from the ossification of the
pulp by the vessels of which it is traversed, and from the
margins of the canals containing which the dentinal tubes
proceed in a radiate manner. (See the figures.)

Mr. Nasmyth regarded this secondary dentinal formation
as distinct from the other structures of the tooth, and called
it the fourth dentinal constituent.

The dentinal tubes form but one element of the dentine ;
the other is the intertubular substance.

This is described by Mr. Nasmyth as constituted of elon-
gated cells, in the form of bricks placed end to end, and a
tier of which exists between every two tubes : Henle, on
the other hand, declares it to be fibrous. It would appear
not to present any regular tissue, but to be simply granular.

Occasionally, I have encountered in it globules of various
sizes refracting the light strongly, and presenting the appear-
ances of oil or fat vesicles. It has occurred to me that these
might be fat cells which had become included in consequence
of the ossification of the pulp, and which always contains a
greater or less quantity of fat cells. (See figure.)

* See Lectures in Medical Gazette.

TEETH. 317

Some sections of dentine which I have examined have ex-
hibited numerous reticulated markings, the results of fracture
of the intertubular tissue, and occasioned probably by the
preparation of the section. Fracture of the dentine is capable
of reunion.

Cementum. — Of the cementum it will not be necessary to
say very much, it possessing the structure of bone and con-
taining both bone cells and Haversian canals; the latter,
however, but seldom. (See the figures.)

The quantity of cementum differs in different teeth ; in
many cases it is very inconsiderable, but it usually increases
with age.

In those cases in which there is but a slight development
of cementum, a layer of considerable thickness formed of
numerous, more or less hexagonal cells, and extending over
the whole of that portion of the dentine not covered by
enamel, may in most cases be clearly seen.

This layer Mr. Tomes speaks of as a granular layer ; it is,
however, distinctly and regularly cellular. It is not easy
to decide whether it should be regarded as a distinct and
permanent structure of the tooth, or whether it merely forms
the basement substance in which the cementum is deve-
loped ; my own impressions incline to the former view.*

A layer of granules, having the aspect of imperfectly
developed bone cells, is usually situated apparently between
the dentine and cementum, but really in the substance of
one or other of these ; this layer might well be called the
granular layer, and to it the description of Mr. Tomes seems
more applicable.

Mr. Nasmyth f describes the cementum as passing over the

* The following is Mr. Tomes's description of this layer : — "In the in-
tertubular tissue hemispherical or elliptical cells are found, especially near
the surface of the dentine of the fang, where they form a layer joining
the cement. This in a paper read before the Royal Society I described
as the, granular layer ; on the coronal surface of the dentine they are not
numerous. With these cells the dentinal tubes communicate, as do
others coming from the cemental cells."

f Memoir read before the Medico-Cli inimical Society by Alexander
Nasmyth, Jan. 22d, 1839.

c c 4

3i8 THE SOLIDS.

entire surface of the enamel of the tooth ; this would appear,
so far as the human tooth is concerned, to be an error. A
cellular lamina, however, does really invest the enamel in
very young teeth, but this is soon worn away : this layer,
however, has nothing to do with the cementum, but is con-
sidered by Mr. Tomes to be derived from the inner surface
of the membrane of the tooth sac. It may be seen in the
teeth of the calf and horse.

Cementum, is rarely, if ever developed in the pulp cavity,
although it has been stated to be so by many observers.
The cementum is not unfrequently traversed by tubes,
similar to and derived from those of the dentine.

It will now be very evident that dentine and cementum
do not differ essentially from each other, and that both are
but modifications of ordinary bone.

Enamel. — Examined with an object-glass of one fourth
of an inch focus, the enamel exhibits a fibrous appearance.
. The fibres radiate outwards from the surface of the den-
tine, somewhat in the same manner as do the dentinal tubes
themselves ; they are simple, short, somewhat attenuated
towards either end, and pass towards the margin of the
enamel in a waved manner, sometimes decussating, forming
plaits or folds, and this occurs especially when the surface
of the dentine is concave. Viewed with a glass of the
eighth of an inch focus, they present the appearance of
elongated and many-sided crystals, and in transverse sec-
tions they are seen to be hexagonal or polygonal ; in some
instances, however, and especially in the enamel fibres of
young teeth, a minute canal may be traced running along
each fibre. (See the figures.)

It is uncertain whether each fibre is constituted of a
single cell, or whether several unite to form it : the ap-
pearance in some cases of faint transverse markings would
render it probable that the latter opinion is the correct
One.

Near the surface of the dentine linear interspaces may
sometimes be noticed between the enamel fibres ; with these
spaces the tubuli of the dentine frequently communicate,

TEETH. 319

and when they exist in any number, or extend nearly through
its entire thickness, they produce a pearly appearance of the
enamel, and render it brittle.

Thin longitudinal sections of the enamel in connexion
with the dentine generally exhibit numerous linear fractures,
which extend through its entire thickness, and which most
probably arise from their mode of preparation. Sections of
enamel also usually present numerous wavy lines, and which
are occasioned by the instrument employed in making the
cuttings.

Structure of the Pulp.

The centre of the dentine of all teeth is hollowed out into
a cavity ; this is occupied with a soft and reddish mass easily
separable from the walls of the cavity, the pulp.

The pulp is made up of numerous blood-vessels, the walls
of which are constituted of delicate and nucleated cells, of
nerves, of ganglionic cells, and larger granular cells placed
principally on the surface of the pulp, external to the other
structures which enter into its formation.

These external granular cells are supposed to play an im-
portant part in the development of the dentine, and to
which more particular reference will be made hereafter.

The pain experienced in toothache crises from inflamma-
tion of the nerves of the pulp, and which is frequently left
exposed to the contact of the air in consequence of the
removal of the dentine, by which in sound teeth it is en-
closed, as the result of caries.

DEVELOPMENT OF THE TEETH.

The subject of the development of the teeth may be con-
sidered under two heads : under the first the general develop-
ment of the teeth will be briefly noticed, and under the

320 THE SOLIDS.

second the special development of their several constituents
will be treated of.

Into the various particulars in reference to the general
development of the teeth as organs, it would be inconsistent
with the design of this work to enter at any length. It will
be sufficient to observe that preparations are made for the
formation of the milk teeth at a very early period of intra-
uterine life ; that the first trace of the future tooth is mani-
fest in the form of a papilla placed in the primary dental
groove, and consisting of granular and nucleated cells ; that
around this papilla a membrane is developed, with an open
mouth, thus forming a follicle ; from the margins of this aper-
ture processes of the mucous membrane, of which the follicle
is constituted, are developed, and these uniting with each
other close the opening, and convert the follicle into a
sac. With the closure of the mouth of the follicle, the first
or follicular stage of the development of the teeth is ter-
minated, and the second or saccular stage commences. The
number of opercula developed from the margins of the follicles
is determinate, being two for the incisives, three for the
canines, and four or five for the molars. In the second or
saccular stage, the papilla takes the form of the tooth, of
which it is the representative, the base dividing in the case
of the molars into fangs, and its apex assuming the shape of
the crown of the tooth, in the place of which it stands : in
this stage also a blastemic matter, consisting of plasma and
nucleated cells is developed in the space intervening between
the papilla and the sac, and adherent to the inner surface of
the membrane of the latter, by which indeed it is generated ;
lastly, the papilla become capped with tooth substance or
dentine.

With the passage of the teeth through the gums the
saccular stage terminates, and the third or eruptive stage is
entered upon.

The second or permanent teeth pass through stages pre-
cisely similar to those of the first or milk teeth, the papilla
and follicles being developed in crescent-shaped depressions
placed in the posterior walls of the follicles of the milk

TEETH. 321

teeth, and which together constitute the secondary dentinal
groove.*

Having now obtained a general idea of the development of
the teeth, we shall be prepared to understand the mode of
development of the individual tissues of the teeth, a subject
which has been studied more particularly by Mr. Nasmyth,
Professor Owen, and Mr. Tomes.

Formation of the Dentine. — It would appear to be a uni-
versal law of development that all animal and vegetable
tissues should take their origin in cells ; of this law the teeth
present a striking and beautiful example.

Thus the dentine is formed out of the cells placed on the
formative surface of the papilla or dentine pulp. This view
of the formation of the dentine originated with Mr. Na-
smyth f, and its accuracy has been confirmed by the investi-
gations of subsequent writers, and especially by those of
Professor Owen and Mr. Tomes.

Mr. Owen, in his work " Odontography," describes with
great minuteness the several steps of the conversion of the
cells of the pulp into dentine, and also enters upon the
consideration of the development of the other tissues of the
teeth.

According to Mr. Owen, the cells of the pulp, which are
larger and more numerous on the surface, become arranged
in lines which are placed vertical to that surface ; subse-
quent to this arrangement the nuclei are seen to divide, first

* For further particulars relating to the general development of the
teeth consult the admirable paper of Mr. Goodsir, contained in the
Edinburgh Medical and Surgical Journal. From the researches of that
gentleman we learn that the papillae of the teeth appear in the upper
jaw before the lower ; that those of the milk teeth are developed in three
distinct divisions, a molar, a canine, and an incisor ; that the molar is
the first formed, the canine the second, and the incisor the third ; also
that the first molar is developed before the second, and the first incisor
before the second. In the permanent teeth the papillae, with the excep-
tion of the anterior molar, appear at the mesial line first, and proceed
backwards.

f Memoir on the Development and Organisation of the Dental Tissues
by Alexander Nasmyth, August, 1836.

322 THE SOLIDS.

longitudinally into two portions, each of which becomes a
perfect cell, also provided with a nucleus ; these again divide,
but in a contrary direction, viz. transversely ; thus four
secondary cells are formed within the cavity of the primary
cell, and out of its single nucleus. The number is not,
however, limited to four, but each nucleus may give origin
to many secondary cells. The primary cells are placed end
to end, as are also the secondary cells ; these last elongate
considerably, until at length they coalesce, thus forming the
tubes of the dentine ; the primary cells remaining as such,
and in some adult human teeth being faintly visible. The
primary and secondary cells, however, although placed end to
end, do not form straight lines, but describe greater and lesser
curves, the greater being formed by the primary cells, and
the lesser by the secondary ; these are the curvatures to which
reference has been made in the description of the tubes of
the dentine.

The views of Mr. Tomes *, although not essentially at
variance with those of Professor Owen, yet differ from them
in some important particulars. Mr. Tomes describes the
primary cells themselves as dividing longitudinally into two
or more secondary cells, but not transversely ; subsequent to
this division each cell elongates, and at length unites with
those above and below it, thus forming the dentinal tubes.
Sometimes two cells unite with but a single cell placed beneath
it, and it is in this way that the branches of the dentinal tubes
are produced. Thus, according to Mr. Tomes, the wall of the
primary cell, as well as its nucleus, enters into the formation
of the dentinal tubuli, while, according to Professor Owen,
the nuclei alone give rise to these tubes, the walls of the
parent cells not undergoing elongation, but remaining to con-
stitute a considerable portion of the intertubular tissue.

In the human tooth I have been unable to detect the ex-
istence of the primary cells of the dentine.

Covering the dentine pulp, a thin transparent membrane
exists; this, on its outer surface, is marked with numerous

* Medical Gazette, Lecture V.

TEETH. 323

hexagonal depressions, into which the enamel fibres are re-
ceived.

Formation of the Enamel. • — Reference has been made to a
blastemic matter consisting of nucleated cells embedded in
a granular matrix, and situated between the dentine pulp and
the inner surface of the sac of the tooth ; this is the enamel
pulp.

The cells of which this is formed are larger than those of
the dentinal pulp, more transparent, and with nuclei which
are less distinct ; they adhere to the inner surface of this sac,
which is formed of a process of the mucous membrane of the
mouth itself, and from which indeed they are evolved.

This membrane, like all mucous membranes, consists of two
layers, an outer basement or fibrous and vascular layer, and an
inner colourless and blastemic layer ; and it is from this last
that the enamel cells proceed. It is marked with depressions
similar to those existing on the surface of the membrane of
the dentinal pulp, and into which the terminations of the
fibres of the enamel are received.

It is out of the cells just described that the enamel fibres
are formed, and this in a manner almost similar to that in
which the tubes of the dentine are themselves developed ;
thus the cells are first arranged in vertical lines ; these com-
mence in the depressions on the inner surface of the tooth sac,
and proceed from without inwards. The cells next elongate
until they touch each other by either short or oblique sur-
faces ; some of them coalesce by their extremities, and thus
form fibres in which earthy matter is deposited, and which
at length terminate in the hexagonal depressions situated on
the outer surface of the membrane of the pulp of the dentine.

The nuclei elongate with the cells, and either disappear
altogether or else remain as minute cavities running down
the centre.

At first the union between the fibres is but slight, so that
in newly-formed enamel they may be easily separated from
each other when placed in water, to which they will impart
a whitish appearance, in consequence of their separation and
diffusion through the fluid.

324 THE SOLIDS.

According to Mr. Tomes also numerous spaces exist be-
tween the fibres in newly -formed enamel ; and it is owing to
the presence of these that young enamel owes its opacity and
brittleness.

We thus perceive that the enamel is to be regarded rather
as a modification of the epithelium than of bone.

The development of both dentine and enamel may be well
studied upon the teeth of young pigs, or kittens at the birth.

Formation of Cementum. — The cementum pulp is formed
between the external surface of the dentine and the internal
of the sac of the tooth, it being intimately united to both.

It consists, like the pulps of the other tissues of the teeth,
of nucleated cells embedded in a granular matrix : these cells
are described by Mr. Tomes * as resembling those of tempo-
rary cartilage, being oval in shape and having their long
axes placed transversely, and at right angles to the length of
the tooth.

The cells nearest the surface of the dentine are the first
to become ossified ; and when their ossification and develop-
ment is completed, they form the stellate or bone cells of the
cementum. Some consider that the nuclei of these cells alone
give origin to the bone cells, and appearances may be observed,
even in adult cementum, which are favourable to this opinion.

The cementum is often seen to be traversed by fibres
derived from the outer layer of the membrane of the tooth-
sac, as well as by tubes prolonged into it from the dentine.

Notice has already been taken of the small hexagonal cells
contained in the cementum, and situated principally upon
the outer surface of the dentine, and a doubt was expressed
whether these were to be regarded as forming a part of the
structure of the cementum, or whether they constituted a
distinct organisation.

The cementum is particularly liable to an increased and
abnormal development constituting exostosis.

It would thus appear, on the one hand, that the cementum
and dentine are but modifications of each other, and also of

* See Lecture V.

TEETH. 325

one and the same tissue, the osseous ; while on the other, it is
evident that the enamel is a modification of the epithelium.

Mr. Nasmyth describes the cementum as passing over the
crown of the tooth and surface of the enamel, in a thin layer
composed of hexagonal cells and fibres; this layer exists only
on the surface of the enamel of the young teeth of the human
subject, and it is not composed of dentine, but consists of
either a few of the unelongated cells of the enamel pulp, or,
as Mr. Tomes considers, of the inner surface of the sac of the
tooth.

Nature of Caries of the Teeth.

Various opinions have been entertained in reference to the
nature of the peculiar decay denominated caries, to which
the teeth are so liable. Some have supposed that it is a
vital process resulting from inflammation. The fact that dead
teeth, that is, teeth which have been removed from the jaw
and are again employed as artificial teeth, undergo a similar
decay to that which affects the living teeth, proves that it is
not essentially a vital action, although it cannot be ques-
tioned but that the condition of vitality and the state of
development of the teeth must exert a powerful influence
over the progress of the decay. Other observers regard the
decay of the teeth as a purely chemical phenomenon, the
earthy matter of the teeth being removed by the action of
free acid in the saliva : this view of its nature certainly ex-
plains many of the circumstances connected with dental
caries, and is supported by the fact already cited, viz. that
dead teeth are susceptible of the change.

Two facts, however, require to be determined before the
chemical theory of the decay of the teeth can be considered
to be proved ; first, that the saliva is in every case of dental
caries really acid ; and second, that the portion of the tooth
which is subject to the carious action is really dead : upon
both of these points considerable doubts may be entertained.

For myself I have long entertained the idea that the real
and proximate cause of the decay of the teeth was to be
found in the presence of some parasitical production, and

326 THE SOLIDS.

that the condition of vitality of the teeth and of the states of
the saliva were to be considered merely as predisposing causes
to the affection.

This idea acquires some confirmation from an examination
of the carious matter of a tooth ; in it vast quantities of minute
threads or filaments, possibly those of a fungus, are invariably
to be discerned, as well as numberless dark granules and irre-
gular masses bearing in some cases the aspect of true cells.

The question may be asked, are these threads, granules,
and cell-like masses any thing more than the decomposing
elements of the dentine, in which tissue it is that the chief
ravages of the decay occur ? The answer is, possibly not ;
but the surprising numbers of these filaments and the testi-
mony of Mr. Tomes are opposed to the idea that they are the
remains of the tubes of the destine. Mr. Tomes thus writes
in his tenth Lecture in reference to the tubes of the dentine :
— " A transverse section of carious dentine, rendered soft like
cartilage from the loss of its lime, presents a cribriform ap-
pearance. The tubuli seem enlarged and rather irregular,
quite unlike the figure they present in healthy dentine : this
would indicate that the solvent enters and acts upon the
parietes of the tubes previous to affecting the intertubuiar
tissue, and that the parietes of the tubes are therefore the
first to disappear. I feel quite certain that in the cases I
have examined, and they are numerous, the parietes of the
tubuli, so distinguishable in healthy dentine, have almost, if
not wholly, disappeared with the removal of the lime."

Nature of Tartar on the Teeth.

Tartar of the teeth consists of phosphate of lime mixed up
with the mucus of the mouth and epithelial scales : it con-
tains also occasionally animalcules and vegetable growths,
which find in the animal matter of the tartar a convenient
nidus for their development. The accumulation of tartar
around the necks of the teeth results from an opposite condi-
tion of the saliva to that to which chemists ascribe dental
caries, viz. an alkaline state of it.

CELLULAR OR FIBROUS TISSUE. 327

ART. XVII. CELLULAR OR FIBROUS TISSUE.

THE truth of the scientific dictum that every living thing
proceeds from a germ or ovum is now generally admitted,
and so also it may be said that each portion of the fabric of
such living entity takes its origin in a cell, the early and
embryonic condition of every organ and structure being
reducible to that of a cell.

It was not, however, this consideration that induced the
older anatomists to apply the tewn cellular to the tissue about
to be described, they having but little knowledge of the
structure of the elementary cell, or of its universal presence.

They were led to denominate the tissue, into the descrip-
tion of which we are about to enter, cellular, in consequence
of observing the areolae or spaces left between the fibres of
which it is composed, and which they erroneously considered
to be cells. The cellular tissue, then, though like all other
tissues, taking its origin in cells, inasmuch as in its fully
developed state it consists of fibres, would be more accu-
rately denominated the fibrous tissue, as indeed by many
modern anatomists it really is: the term cellular tissue is,
however, one of so ancient a date, and one, moreover, in such
general use, and so well understood, that it seems to be
scarcely advisable to abandon the use of it altogether.

The cellular or fibrous tissue, however, as ordinarily en-
countered, is constituted not of a single description of fibre,
but consists of two kinds intermingled in different propor-
tions, and each of which is possessed of distinct characters
and properties.

The most remarkable difference between the two de-
scripti6ns of fibrous tissue is, that the one is white and
inelastic, and the other yellow and elastic : each of these will
be described under different heads, and the former before
the latter.

r> D

328 THE SOLIDS.

INELASTIC OR WHITE CELLULAR OR FIBROUS TISSUE.
Tendons, Ligaments, Membranes, fyc.

The inelastic fibrous tissue is very generally distributed
throughout the body : it constitutes the principal portion of
tendons, ligaments, and fasciae ; of the fibrous membranes,
the dura mater, pericardium, periosteum, perichondrium,
tunica albuginea of the testicle, and sclerotic coat of the eye ;
also of the serous, synovial and mucous membranes, as well
as of the skin, and it forms likewise the principal constituent
of the loose cellular tissue which is so abundantly developed
throughout every tissue and organ of the body, but which is
invariably present in large quantities wherever motion is ne-
cessary, as in the axilla, between the fasciculi of muscles,
and in the course of the vessels.

When endowed with a distinct form, as in the case of the
tendons, it may be called morphous inelastic cellular tissue,
and when it has no circumscribed shape, the term amorphous
may be applied to it : when constituting membrane, it exists
in the state of condensed fibrous tissue ; and when it merely
binds organs together, or allows of the motion of parts, it
may be called loose or reticular cellular tissue.

There is, however, a form of the inelastic fibrous tissue
which requires not merely a separate name, but a distinct
notice. This form is met with in the great omentum, and
consists in the fact of spaces of irregular size and form being
left between the fibres, and hence it may be termed areolar
cellular tissue. The best examples of it are met with in
the omenta of children and lean persons, which contain but
little fat. (See Plate XL. Jig. 4.)

The inelastic cellular tissue is made up of innumerable
unbranched threads or fibres of equal calibre, of great te-
nuity, which appear white to the unassisted sight, but of a
yellow colour when viewed under the microscope, and which
have a great disposition to assume a waved or zigzag ar-
rangement, the folds formed being comparable to those in

CELLULAR OR FIBROUS TISSUE. 329

which a loose skein of silk is often observed to fall. (See
Plate XXXIX. fig. 6.)

When dried, the inelastic cellular tissue assumes the trans-
parent appearance and consistence of horn : in water the
fibres swell up somewhat, become opaque and white, but still
preserve their form: in acetic acid they swell up greatly,
become indefinable, soft, and gelatinous: the addition of a
mineral acid will, however, bring the fibres again into view.

The remarkable effect of acetic acid on the inelastic fibrous
tissue has suggested the idea to Mr. Bowman that (( it is
rather a mass with longitudinal parallel streaks (many of
which are Greasings), and which has a tendency to slit up
almost ad infinitum in the longitudinal direction."

There are several considerations which may be urged in
disproof of this view ; the first is, the mode of development
belonging to this tissue ; the second, the fact that the fibres
are all of nearly an equal diameter ; and the third is, that the
tissue still retains its fibrous constitution even after the ap-
plication of acetic acid.

The white fibrous tissue is employed wherever a strong
and inelastic material occupying but little space is required.

A degree of elasticity not unfrequently appears to belong
to this tissue ; but this is rather apparent than real, and de-
pends upon the extent of its admixture with the next form of
fibrous or cellular tissue to be described, viz. the elastic.
(Plate XXXIX. fig. 7.)

ELASTIC CELLULAR OR FIBROUS TISSUE.

The elastic cellular or yellow fibrous tissue is distinguished
from the inelastic form by its branched filaments, the dia-
meter of which is unequal, its elasticity, its deeper colour,
and the absence of any appreciable effect on the addition of
acetic acid. (See Plate XL. Jig. 1.)

Like the inelastic fibrous tissue, it rarely occurs in an
unmixed form, being mostly intermingled with it in variable
proportions: thus it is encountered in tendons, ligaments,
and, indeed, in all forms and conditions of the inelastic

D D 2

330 THE SOLIDS.

cellular tissue ; it constitutes the principal portion of the
ligamenta subflava and nuchre, of the transverse fascia of
the abdomen, of the cricothyroid and thyrohyoid membranes,
of the chordae vocales, of the internal lateral ligament of the
lower jaw, of the stylo-hyoid ligaments, of the middle coat of
the arteries, and of the membrane uniting the rings of the
trachea and its ramifications. It is also met with in con-
siderable quantities beneath the mucous membrane of the
esophagus, at the base of the epiglottis, in maintaining which
in the erect position it is probably mainly instrumental, in the
lungs and in the integuments of the penis.

The elastic cellular tissue presents some differences of ap-
pearance and structure, in certain of the situations in which it
is encountered : thus, in the tendons and in the smaller blood-
vessels (Plate XL.J&7S. 1, 2, 3. 5.) the fibres are very slender,
appear to be but little branched, and contain at intervals
nuclei in the same manner as do the fibres of unstriped
muscles ; in the reticular cellular tissue again, they are slen-
der, unbranched, and without nuclei (see Plate XXXIX.
Jig. 7.) ; in the ligamenta flava and nuchae, in the cricothyroid
and thyrohyoid membranes, the fibres are thick, much
branched, curled, and interwoven, but they do not present
nuclei (see Plate XL. fig. 1.) ; in the larger arteries, the
fibres are slender, and are united together so as to form
areolae (see Plate XL. fig. 2.), while in the smaller blood-
vessels they are distinctly nucleated, as already observed.

There is little doubt but that the several forms of elastic
tissue just described do really represent different stages and
states of the same structure ; and it will be observed, that
some of them, and especially that of the small blood-vessels,
approach very closely in structure and appearance to that
of unstriped muscular fibre : the fibres of the former differ,
however, in being sparingly branched, and in their more
slender diameter.

It is not easy, without the addition of re-agents, to distin-
guish the two forms of fibrous or cellular tissue from each
other when mixed together: nevertheless, when the two are
well separated, the elastic fibres may be frequently singled
out from the inelastic, in consequence of their presenting

CELLULAR OR FIBROUS TISSUE. 331

a darker and stronger outline, as well as of their following
a more curled and tortuous course. (See Plate XXXIX.
fig. 7.) Acetic acid applied to a portion of mixed cellular
tissue, at once allows the elastic fibres to be clearly seen,
rendering the inelastic fibres transparent, and almost in-
visible.

There are several parts of the human organisation de-
scribed by modern minute anatomists and physiologists as
being in part composed of unstriped muscular fibre ; these
are the skin, dartos, nipple, clitoris, penis, the ducts of the
larger glands, as the ductus communis choledochus, the
ureters, and vasa deferentia. Now, I find that all these
parts, which I have examined with care, owe their contrac-
tility, and their power of erection, to the presence of the
nucleated form of the elastic tissue which has been described
as existing in tendons and the smaller blood-vessels, and
not to any form of muscular fibre ; and further, that in the
majority of them, and especially in the dartos, penis, clitoris
and nipple, this elastic tissue is confined almost entirely to
the blood-vessels, the walls of which it constitutes : this
fact may be readily ascertained in the instance of the dartos
by taking a small fragment of that membrane when in a
fresh condition, and having spread it out on the surface of
a piece of glass without the addition of any fluid, then
submitting it to the microscope, when the number, size,
and course of the blood-vessels may be traced, and the
disposition of the intervening fibrous inelastic tissue recog-
nised : in the recent state, however, the vessels are filled with
blood, the presence of which prevents the satisfactory de-
tection of the elastic constituent of the blood-vessels : if now,
however, acetic acid be applied to the fragment of membrane
thus spread out, the inelastic fibrous tissue will become in-
distinct, the red blood corpuscles contained in the vessels
will be dissolved, and the tissue of the blood-vessels clearly
brought out. (Plate XLIII.^. 3.)

The extent of contraction of which the dartos is suscep-
tible is very great, and the act of contraction must of course
exert a very powerful influence over the circulation of the

D D 3

332 THE SOLIDS.

blood in its vessels. In the contracted state of this mem-
brane the slender fibres of the elastic tissue as well as their
nuclei are frequently curled up in a spiral manner, an ar-
rangement by which any amount of shortening may be secured.

The contraction of the tissue of the dartos, and indeed of
all elastic tissue, is evidently not a physical, but a vital act :
this is shown by the relaxation and contraction which it ex-
periences in sympathy with the condition of the vital powers,
as well as with any causes, as heat and cold, which affect
these powers.

The corpora cavernosa penis and corpus spongiosum urethra
are almost entirely composed of blood-vessels, and the
peculiarity of these parts consists in the large size of the
vessels and in their repeated inosculation. (Plate XLIII.

fig- 4.)

In the lungs, the blood-vessels are so numerous, that they,
in this ease, also constitute the principal portion of the fabric of
these organs : — this may be beautifully seen in the lungs of
the lower reptiles, as the triton and frog.

Henle has described a peculiar arrangement of the
fibres of elastic tissue. ee I have already said," he remarks,
" that the fibres of the cellular tissue are for the most part
united into ;a number more or less considerable, and thus
form flattened bands of different thickness. These bands
unite in their turn to produce others larger, or even mem-
branes, and thus sometimes they apply themselves paral-
lelly to each other ; at others, they cross each other in the
most varied directions. When the cellular tissue fills the
interstices of organs under the form of a soft mass, easy to
displace, and extensible, the bundles may be perceived with-
out the least preparation, seeing that they cross and inter-
lace in all directions, and that even to the naked eye they
represent a network of delicate fibres. The size of the
bundles, which I call primitive bundles, or after their
origin, the fibres of the cells of cellular tissue vary from
the 0-003 to the 0-006 of a line. The majority of the
primitive bundles are deprived of special envelope : the fibres
may easily be detached, the one from the other, and separate,

CELLULAR OR FIBROUS TISSUE. 333

when one bends a bundle strongly. But in many situa-
tions they are interlaced, and held together by filaments,
which differ from the fibres of cellular tissue by their
chemical and microscopical peculiarities, while in certain re-
spects they approach the fibres of elastic tissue ; of which
we shall give a description further on. They are almost
still finer than the fibres of cellular tissue, quite flat and
homogeneous, but with outlines much more obscure, and
they are distinguished, above all, by the considerable folds,
which they describe when they are in a state of separation.
In order to recognise them, it is necessary to place the cellular
tissue in contact with acetic acid : in this acid the bundles
of cellular tissue become transparent, swell, and cease to
appear fibrous, while the filaments which envelope them
undergo no change. In this manner it happens that a
bundle, which appears to be composed of the ordinary
interlaced fibres of cellular tissue, comports itself after
having been treated with acetic acid, as a transparent
cylinder divided by contractions often very regular, and
which one soon observes to be caused by a filament which
runs spirally around the bundle ; or also by separated rings
placed at a greater or less distance from each other. I have
rarely succeeded unreducing the turns to a single filament,
and I am obliged in consequence to leave undecided the
question, whether it does not sometimes happen that many
filaments are rolled spirally around a bundle. The forma-
tions which I have described show themselves in no part in
a more beautiful manner than in the delicate and firm
cellular tissue, which is situated at the base of the brain
beneath the arachnoid, between the vascular trunks and the
nerves, and which becomes distended into isolated filaments,
on extension, as for example, in any part of the circle of Willis.
There I have never sought the spiral filaments in vain ;
nevertheless analogous bundles, encircled with spirals, may
be seen also upon other parts of the economy, in serous
membranes, in the subcutaneous cellular tissue, in the skin,
and even in the tendons." *

* Anat. Gen. vol. i. pp. 377, 378.

D B 4

334 THE SOLIDS.

It appears to me that Henle has misunderstood the struc-
ture, and consquently the nature of the formations noticed
by him: there can be little doubt but that these, in place
of being bundles of filaments composed of inelastic fibrous
tissue encircled with a spiral coil of elastic tissue, are in
reality hollow cylinders, vessels in fact in progress of form-
ation, consisting of, in the stage described by the German
physiologist, an inner transparent and apparently structureless
tunic, enclosed in a coil of elastic fibrous tissue.

The correctness of this view is established by the very
convincing fact, that the tubular formation in the condition
just described may be traced up to the state of perfect blood-
vessels, some of which may also now and then be seen divid-
ing into branches, and containing, moreover, blood corpuscles.
Several of the stages of the development of these vessels are
seen in Plate XL. fig. 3.

DEVELOPMENT OF CELLULAR TISSUE.

Exact observations are still required on the subject of the
development of both the elastic and the inelastic forms of the
cellular or fibrous tissue, and especially of that of the latter
form. Schwann and all other observers after him have
described the cellular tissue as taking its origin in cells of
an elongated form, from the extremities of which fibres,
mostly branched, proceed, the cells themselves ultimately be-
coming absorbed: microscopists, however, have not as yet
attempted to point out the differences which doubtless exist
in the development of the two forms of cellular tissue, but
have for the most part contented themselves with the above
general description.

It appears to me that the observations already made on
the development of the cellular tissue apply only to the
yellow or elastic kind; and to this conclusion I am led by
the fact that observers describe the elongated nuclei as giving
origin to branched filaments ; and we know that the fibres of
the inelastic fibrous tissue are simple, and not branched.

DEVELOPMENT OF CELLULAR TISSUE. 335

According to my observations, both forms of cellular
tissue originate in cells.

The cells of the white fibrous tissue exist first as rounded
nuclei, around which the cell wall gradually makes its appear-
ance, and these cells when fully formed are large, granular,
elongated, fusiform, and from each extremity at length pro-
ceeds a single unbranched thread, which gradually becomes
extended into a filament or fibre, which is produced by the
growth and extension of the cell wall itself, and the extremity
of which unites for the production of an elongated thread
with that proceeding from the other cells placed above and
below it : finally, the process terminates by the absorption
of the nuclei. (See Plate XLIII. Jig. 2.)

The cells of the yellow fibrous tissue also exist, at first as
nuclei, then as fusiform cells, but differ from those of the
white fibrous tissue in the subsequent steps of their develop-
ment, in that the cells are disposed in lines, each fibre being
formed, as is the case with the unstriped muscular fibre, by
the union of the filaments, proceeding from each series of
linearly disposed cells, and in that the filaments proceeding
from the cells are very frequently branched. (See Plate
XXXIX. figs. 1, 2. Plate XL. figs. 3. 5.)

The above described mode of development may be fol-
lowed out in longitudinal and cross sections of tendon treated
with acetic acid, also in the smaller vessels of the pia mater,
and in those placed in the mixed cellular tissue which sepa-
rates ' the different striped muscular fasciculi : we thus per-
ceive, that in the case of the yellow fibrous tissue, many
nuclei are required to form a single filament ; and further,
that there is a strong analogy in the mode of its develop-
ment with that of muscular fibre, as also in the physical pro-
perties of the two tissues.

In the fibrillation of the fibrin of the blood we have an
example of the formation of filaments independently of any
development from cells, and at one time I conceived that the
fibres 'of the white fibrous tissue might possibly originate in
a similar manner.

336 THE SOLIDS.

ART. XVIII. MUSCLE.

FEW of the animal tissues have been more extensively
examined than the muscular: the multiplied observations
made on its structure have, however, led neither to that uni-
formity of opinion respecting it, nor, indeed, to that accurate
knowledge of its minute anatomy which might have been
anticipated; of the truth of this position, evidence will be
shortly adduced.

Muscles admit of division into the voluntary, or those
which are under the control of the will, and the involuntary,
or those of which the action takes place independently of
the will ; the former consist of the muscles of animal life,
those, for example, of locomotion, and the latter embrace
those of organic life, as the muscles of the alimentary canal
(the sphincters of the oesophagus and anus excepted, which
are to a certain extent voluntary), the heart, the uterus, the
bladder, &c.

It will be observed, that the involuntary muscles, or
those of organic life, usually encircle the hollow viscera:
there are some other situations, however, in which involun-
tary muscular fibres are met with, as in the trachea and its
bronchial ramifications, the iris, the sarcolemma, and, ac-
cording to some observers, as Bowman, they are also en-
countered in the dartos and covering the excretory ducts
of the larger glands, as the ductus communis choledochus,
the ureters, and vasa deferentia ; and it is with them a
matter of question how far the contractility of the skin,
and the erection of the penis, clitoris and nipple, may be de-
pendent upon the presence of involuntary muscular fibrilla?.
In the preceding article I have, however, shewn that the
contractility of these parts depends upon the presence of a
nucleated form of elastic tissue allied to unstriped muscular
fibre in many of its properties, but yet distinct therefrom.

MUSCLE. 337

Corresponding with the division of muscles into voluntary
<ind involuntary, there exist differences of structure: thus,
the muscles under the control of the will are all striped,
while those which are not under its influence are unstriped.
To this rule, however, one remarkable exception may be men-
tioned, viz. the muscles of the heart, the action of which is
to a great extent involuntary, and which are yet striped : this
exception is rather apparent than real, as will be seen here-
after.

STRUCTURE OF MUSCLE.

A striped muscle is made up of a number of unbranched
fibres, each of which is included in a distinct sheath, the
sarcolemma, and consists of a number of threads or fibrillse :
the fibres again are collected into sets or bundles called
lacerti; these are held together, and yet separated by a
mixed form of cellular tissue, which also contains fat vesicles
blood-vessels, and nerves.

An unstriped muscle consists of fibrillse, intermingled with
fibrous tissue : these do not form fibres, and consequently
there is no sarcolemma.

Between striped and unstriped muscle there is no essential
or specific structural difference: the one is not to be re-
garded as typically distinct from the other, but both should
rather be considered as different conditions in the develop-
ment of one and the same tissue. Of this position, evidence
will be hereafter adduced.

According to the above view, muscular fibre presents
two grand stages of development ; the first of which is repre-
sented by the unstriped fibrilla, and the second by the
striped muscular fibre.

We shall first describe the structure of the unstriped
muscular fibrilla, because it represents an earlier condition
of development than the striped.

Structure of Unstriped Muscular Fibrilla. — Unstriped
muscles consist of fibrillae which are unbranched, rather broad,

338 THE SOLIDS.

somewhat flat, and which contain imbedded in their substance,
elongated, and granular nuclei. (See Plate XLI. Jig. 2.)

The fibrillas usually run parallel to each other, and form
thin layers and fasciculi, which are separated from each
other by cellular tissue, and frequently interlace.

The nuclei are sometimes imbedded in the substance of
the fibrillae, without at the same time increasing their dia-
meter : at others they render the fibrillae ventricose from
their great size ; and again, in other cases, they protrude
from their sides. (See Plate XLI. fig. 2.) They are best
seen after the addition of acetic acid.

Unstriped muscles are doubtless freely supplied with
blood-vessels and with nerves.

The unstriped muscle is called into action with greater
difficulty than the striped ; its action is also slower, and of
a peculiar kind, giving rise to the vermicular and peristaltic
motion, seen especially in the intestines.

This slower and less energetic action results from its lower
degree of organization.

The muscular structure of the heart, the action of which is
to a considerable extent involuntary, requires a special de-
scription. The muscular tissue of this organ has been usually
supposed to constitute an exception in its structure to that of
other involuntary muscles, and that while it performed the
office of an involuntary muscle, it yet possessed the structure
of a voluntary muscle, its fibres being striped.

Mr. Bowman, one of the very best authorities on the struc-
ture of the muscular fibre, gives the following description of
the tissue of the heart. " The cross stripes on the fibres of
the heart are not usually so regular or distinct as in those of
the voluntary muscles. They are often interrupted, or even
not visible at all. In some of the lower animals their sarcous
elements never form transverse stripes. These fibres are
usually smaller than the average diameter of those of the
voluntary muscles of the same subject by two-thirds, as stated
by Mr. Skey." *

This description is very imperfect, and in some respects,
* Physiological Anatomy, p. 161.

MUSCLE. 339

according to my observations, incorrect. Thus, the muscular
substance of the heart does not form fibres at all, but consists
simply of fibrilla?, which agree in every respect with those of
other involuntary muscles, save in their transverse striation :
thus they have the same considerable diameter : they are, in
like manner, abundantly nucleated (see Plate XLI. Jig. 3.),
and they have the same arrangement, interlacing with each
other, and not forming fibres included in a sarcolemma, as is
the case with the voluntary muscular tissue. The transverse
striae, too, have not the deep and permanent character belong-
ing to the fibrillaB of ordinary striped muscle, as is evinced
by the fact that acetic acid effaces all vestige of striation. -

It thus appears that the muscles of the heart agree in
structure much more closely with that of other involuntary
muscles, which is contrary to what is generally supposed,
than they do with that of the voluntary muscles.

Thus then the structure and the function of the muscles of
the heart are in accordance, and not in antagonism, as is usu-
ally conceived, the single point of difference between its fibrilla3
and those of other involuntary muscles consisting in the feeble
transverse striation, the presence of which evinces a somewhat
higher degree of development, as well as a greater power of
contractility.

Structure of Striped Muscular Fibre. — The striped muscle
consists of fibres : each of these is included in a distinct enve-
lope, termed Sarcolemma, and is made up of a number of
lesser fibres or fibrilhe. (See Plate XLIL fig. 1.)

The fibres vary very considerably in size, not merely in
different animals, but also according to the age of an animal, and
even in a single bundle of the same animal, some of them being
three or four times larger than others, and the smaller being
usually adherent to the larger fibres ; a fact which has refer-
ence to the development of muscular tissue, and which will
be explained when we arrive at the consideration of that
portion of our subject. (See Plate XLIL fig. 4.) The dif-
ference in the size of the fibres according to age is very re-
markable, those of the foetus being several times smaller than
the fibres of the adult. (See Plate XLIL fig. 1. and Plate
XLIII. fig. 1.)

340 THE SOLIDS.

They differ also to a very considerable extent in form as
well as magnitude : thus, in a cross section and in a recent
state they are seen to be more or less angular and compressed,
but still preserving, in most cases, much of the character of
cylinders. In the dry condition this angularity is greatly
increased, and to this state of the fibres the representations
hitherto given chiefly refer. (See Plate XLII. fig. 5.)

The fibres, both great and small, are, as already observed,
arranged in bundles or lacerti, of variable size ; those of the
same bundle run parallel to each other, and the different
bundles are separated, and yet held together by mixed fibrous
tissue.

Examined with a moderate power of the microscope, each
fibre is seen to exhibit numerous transverse striae, which are
placed at tolerably regular distances from each other : some
fibres, also, and especially such as have been preserved in
spirit, present numerous fainter longitudinal striae.

When viewed with a somewhat higher object glass, and
when each fibre has been torn into pieces by needles, its
entire bulk will be seen to be made up of a number of slender
threads of equal diameter, which present a distinct trans-
verse striation.

It was formerly very generally supposed that the transverse
lines on the striped muscular fibre were produced by a fila-
ment which wound spirally around it : this notion is, doubt-
less, erroneous, as indeed it is now generally allowed to be.

It has been observed that the fibrillae are themselves
marked with transverse striae : now it is not difficult to con-
vince oneself that the striation of the fibre is produced by the
striae of the fibrillae, the striae of one fibrilla corresponding
with that of another, and thus giving rise to a line which
extends entirely across the diameter of the fibre.

The correctness of this explanation might have been easily
inferred from a knowledge of the composition of the striated
muscular fibre of banded fibrillae, and from the aspect of
the transverse line itself, which, when examined with a high
power of the microscope, does not present the appearance of
an uninterrupted and continuous line, such as would be pro-

MUSCLE. 341

duced by the winding of a filament around it, but rather of
a line formed by the apposition of a series of dots or shorter
lines ; in which manner, indeed, it is that the striation of the
fibre is really produced, as we have seen.

The fibrillae contained in each fibre are unbranched, of
great tenuity, of nearly equal diameter (see Plate XLIL
fig. 1.), and their number varies greatly, amounting in the
larger fibres to as many as fifty or sixty, while in the smaller
they may not exceed from one to five and upwards, according
to the breadth of the filament.

The striae present a very uniform and strongly marked
character : the spaces between them are not, however, equal :
thus, they are sometimes rather longer than the diameter of the
fibrilla : at other times, they are shorter, and when the stria}
are very close, the fibrilla becomes ventricose or moniliform.

Much difference of opinion prevails as to the nature of the
striation exhibited by the fibrillae. Drs. Sharpey * and
Carpenter f incline to the opinion that each fibrilla consists
of a series of particles or cells cohering in linear series, and
that the lines indicate the point of junction of these ; Mr.
Erasmus Wilson \ attributes a still more complicated struc-
ture to the striated fibrilla. He believes that two kinds of
cells exist in each fibrilla ; a pair of light cells separated by a
delicate line, being interposed between each pair of dark
ones.

Lastly, Bowman considers that the lines indicate the
divisions between particles, which he denominates " sarcous
elements."

My own view of the nature of these lines differs from that
of all the gentlemen named. I consider that the lines in
question are produced by the simple corrugation or wrinkling
of the threads at regular distances : a view, the accuracy of
which is all but proved by a consideration of the development
of muscular fibre, and by the action of acetic acid on the
fibrillae of the heart, the transverse markings of which it en-
tirely obliterates.

* Quain's Anatomy, 5th edition, vol. ii. p. 168.

f Human Physiology, p. 176.

j Manual of Anatomy, 3d edition, p. 16 .

342 THE SOLIDS.

The fibrillae are, as already stated, included in a sheath,
the sarcoleinma of Bowman, both together constituting the
fibre. The sheath cannot at all times be seen : it may, however,
frequently be so, and especially when the fibrillae have been
torn across, the sheath at the same time not having been
divided, its greater elasticity enabling it to resist the force
which was sufficient to rupture the muscular fibrillae. It is in
such cases that the best view of this membrane is obtained.
(See Plate XLIL.,%. 1.)

Treated with acetic acid, each fibre discloses most dis-
tinctly a considerable number of elongated and granular
nuclei, the outlines of which are in some cases visible, even
without the application of the acid. (See Plate XLIL

fig- 2.)

Of these nuclei, Mr. Bowman remarks : " In the fully
formed fibre if it be large, they lie at various depths within
it ; but if small, they are at or near the surface. They are
oval and flat, and of so little substance, that though many
times larger than the sarcous elements, and lying amongst
them, they do not interfere with their mutual apposition and
union." " It is doubtful whether the identical corpuscles,
originally present, remain through life, or whether successive
crops advance and decay during the progress of growth and
nutrition: but it is certain that as development proceeds
fresh corpuscles are deposited, since their absolute number is
far greater in the adult than in the foetus, while their number
relatively to the bulk of the fibre at these two epochs re-
mains nearly the same." *

The above description is in part only correct. Thus I find,
first, that the nuclei are invariably situated on the external
surface of the fibre, the majority within the sheath, and either
adherent to this, or to the exterior fibrillae, some also being
placed on the outer surface of the sarcolemma ; facts which
throw much light upon the development of the muscular
fibre ; secondly, that the nuclei are not usually free nuclei, but
are contained in most cases in filaments in every way similar

* Physiological Anatomy, vol. i. pp. 158, 159.

MUSCLE-. 343

to those of unstriped muscle, and with which they are iden-
tical.

"Were the nuclei really scattered throughout the substance
of a muscular fibre, they would infallibly destroy the paral-
lelism of the stride, and greatly interfere with its contractile
power.

The interpretation to be given of the location of the nuclei
and fibres of unstriped muscle in the situations indicated
will be explained when the subject of the development of
muscular fibre is considered ; at the same time, also, the point
raised by Mr. Bowman as to the persistence of the nuclei will
be discussed.

The fibres of the upper part of the esophagus are striped
while those of the lower half are unstriped. It has been
considered a matter of uncertainty whether the two pass by
insensible gradations of structure into each other, or whether
they terminate abruptly. I believe, after careful examination,
that the latter supposition is the correct one.

With a few remarks upon the peculiar views entertained
by Mr. Bowman, in reference to the structure of the striated
muscular fibre, the discussion of the structure of muscle may
be brought to a conclusion.

" It was customary," writes Mr. Bowman *, " both before
and since his time (the time of Fontana), as at the present
day, to regard the fibre as a bundle of smaller ones, whence
the term primitive fasciculus, first given to it by him, and
adopted by Miiller : but this view of ihe subject is imper-
fect. The fibre always presents, upon and within it, longi-
tudinal dark lines, along which it will generally split up into
fibrillae ; but it is by a fracture alone that such fibrillse are
obtained. They do not exist as such in the fibre. And
further, it occasionally happens that no disposition whatever
is shown to the longitudinal cleavage ; but that, on the con-
trary, violence causes a separation along the transverse dark
lines, which always intersect the fibre in a plane perpen-
dicular to its axis. By such cleavage discs, and not fibrilla?,

* Physiological Anatomy, vol.). pp. 151, 152.
E K

344 THE SOLIDS.

are obtained, and this cleavage is just as natural, though less
frequent, than the former. Hence it is as proper to say
that the fibre is a pile of discs as that it is a bundle of
fibrillas : but, in fact, it is neither the one nor the other, but
a mass in whose structure there is an intimation of the ex-
istence of both, and a tendency to cleave in the two direc-
tions. If there was a general disintegration along all the
lines in both directions, there would result a series of particles,
which may be termed primitive particles., or sarcous elements,
the union of which constitutes the mass of the fibre. These
elementary particles are arranged and united together in two
directions. All the resulting discs as well as fibrilla3 are
equal to one another in size, and contain an equal number
of particles. The same particles compose both. To detach
an entire fibrilla is to abstract a particle of every disc, and
vice versa. The width of the fibre is therefore uniform, and
is equal to the diameter of any one of its fibrilla?, and is
liable to the greatest variety."

This view of the structure of the striated muscular fibre is
ingeniously conceived and well expressed; nevertheless it can
be shown, I think, notwithstanding its ingenuity, to be in-
correct.

There are two considerations which appear to me to be
sufficient to disprove the view just propounded. The first is,
that the rudimentary muscular fibre consists of one or more
threads or fibrillaj, containing imbedded in them a number of
elongated nuclei, which, however, have no correspondence
with the transverse markings ; and the second is, that, while
any muscular fibre may at any time be readily separated into
its component fibrillae, the simultaneous transverse cleavage
spoken of and figured by Mr. Bowman is an occurrence of
extreme rarity, and one, moreover, of which I have never
been able to perceive the slightest trace in any muscular fibre
which has fallen under my notice.

It would thus appear that the older view is the correct
one, and that the striped muscular fibre is made up, as al-
ready described, of a variable number of fibrillae enclosed in
a tubular sheath.

Blood Vessels of Muscles. — Muscles are copiously supplied

MUSCLE. 345

with blood vessels : the larger vessels are contained in the
cellular tissue separating the fascicles or lacerti of the muscles,
and which serves to support and to conduct them; the
smaller vessels or capillaries are not encircled by cellular
tissue, but penetrate between the fibres, forming numerous
capillary loops and meshes, having their long axes disposed in
the direction of the length of the fibres. This arrangement
of the capillaries is shown in Plate XLI. Jig. 4.

Much of the colour of a muscle arises from the blood
enclosed in the vessels, but not all, a portion of it being con-
tained in the muscular fibres themselves.

It is evident that the contraction of the fibres exercises
much influence upon the capillary circulation, reducing the
calibre of the capillaries to such an extent as that the blood
corpuscles can pass through them only in an elongated form.

In the course of the larger vessels, imbedded in the inter-
fascicular cellular tissue, fat corpuscles are often abundantly
distributed, as represented in Plate XLI. Jig. 1.

Nerves of Muscles. — Muscles are also abundantly supplied
with nerves, principally those of locomotion. Burdach has
figured and described the nerves in muscles as forming loops,
which either join other neighbouring loops or else return into
themselves. The figure and description given by Burdach
have been adopted by almost all succeeding anatomists ; not-
withstanding which, I would observe, that I have never seen
the nerves terminating in muscle in the manner indicated ;
not, however, that I doubt the fact of their doing so, because
such a mode of termination is common to nerves ; but would
simply infer from this, that the loop- like arrangement is
neither very general nor very obvious.

According, then, to the latest physiologists, nerves, strictly
speaking, really have no termination whatever in muscles :
an opinion the accuracy of which is more than doubtful.

I find that the nerves, after branching in a dichotomous
manner,, have a real termination, and that from time to time
certain tubules leave the main trunks, and end in the form-
ation of elongated and ganglioniform organs situated between
the fibres of muscle. (See Plate XLI. Jig. 4.)

E E 2

346 THE SOLIDS.

UNION OF MUSCLE WITH TENDON.

The unstrlped muscular fibrilla is rarely if ever attached
to tendon or aponeurosis : the striped fibre, on the contrary,
is almost constantly so.

Two errors have prevailed in reference to the union of the
striated muscular fibre with tendon.

The first has reference to the form of the extremity of the
fibre in connexion with the tendon; the second to the precise
mode of junction between the two.

Thus most observers have described and figured the fibre
as terminating in a conical point, from which the fibres of
the fibrous tissue of the tendon proceed in a straight line.

This description is contrary to fact, both as respects the
form of the fibre and its mode of union with the tendon :
muscular fibre is rarely, if ever inserted vertically into a
tendon or aponeurosis ; but in all the instances which have
fallen under my observation, the insertion has been either
oblique or occasionally at right angles with the tendon ; the
extremity of the fibre being in the one case also oblique, and
in the other truncate : this termination is the very opposite
of that usually attributed to it. Let us next see in what
way the two structures are unite.d. In no one instance have
I ever seen the fibres of the fibrous tissue of the tendon
unite themselves directly with the muscular fibre: on the
contrary, the mode of junction has always been effected in
the following manner : — the sheath of each fibre is prolonged
upon the surface of the tendon where the union is oblique,
and certain of the fibres of the tendon are extended upon and
interlace with the terminal portions of the muscular fibres
and their investing sheaths. (See Plate XLII. fig. 4.)

MUSCULAR CONTRACTION.

Many attempts have been made to determine the exact
changes which the muscular fibre undergoes in its passage to

MUSCLE. 347

a state of contraction : these attempts do not appear to me to
be altogether satisfactory and successful.

The earliest opinion formed in reference to muscular con-
traction supposed that, during contraction the fibres and
fibrillas of muscle are disposed in a zigzag manner, such
a disposition of the fibres of course having the effect of
materially shortening the muscle. (Plate XLIII. fig. 5.)

The advocates of this view seem to have overlooked
the fact that fibres thus disposed, having no fixed or direct
points from which to act, would have their power by such an
arrangement rather diminished than increased : this idea has
therefore been justly discarded, and an account of the nature
of muscular contraction, much more closely approximating
to the truth, substituted in its place.

Mr. Bowman, who has written by far the best account of
muscular contraction which has yet appeared, discriminates
between passive and active contraction of muscle : the former
he conceives to be a uniform act, involving and affecting
equally the entire mass of the muscle: the latter, on the
other hand, he considers to be a partial act, implicating, first,
a particular part or parts of a fibre ; subsequently leaving
these, and advancing to other and neighbouring parts of the
same fibre.

This view is founded principally upon the experiment de-
tailed below, made upon a fibre of the claw of a crab, which
still retained its contractility. " In an elementary fibre fron\
the claw, laid out on glass, and then covered with a wet lamina
of mica, the following phenomena are always to be observed.
The ends become first contracted and fixed. Then con-
tractions commence at isolated spots along the margin of
the fibre, which they cause to bulge. At first they only
engage a very limited amount of the mass, spreading into its
interior equally in all directions, and being marked by a
close approximation of the transverse stripes. These con-
tractions pull upon the remainder of the fibre only in the
direction of its length ; so that along its edge the transverse
stripes in the intervals are very much widened and dis-
torted. These contractions are never stationary, but oscil-

K E 3

348 THE SOLIDS.

late from end to end, relinquishing on the one hand what
they gain on the other. When they are numerous along
the same margin, they interfere most irregularly with one
another, dragging one another as though striving for the
mastery, the larger ones continually overcoming the smaller ;
th'en subsiding, as though spent, stretched by new spots of
contraction; and again, after a short period of repose, en-
gaged in their turn by some advancing wave. This is the
first stage of the phenomenon. At a subsequent stage, the
ends of the fibre commonly cease to be fixed, in consequence
of the intermediate portions, by their contraction, receiving
some of the pressure of the glass. The contractions, there-
fore, increasing in number and extent, gradually engage the
whole substance of the fibre, which then is reduced to at
least one third of its original length." *

To this experiment, which I have never been able suc-
cessfully to repeat, some exceptions may be taken. Thus
it is known that water has a powerful and remarkable
effect in exciting muscular fibre which still retains its irrita-
bility to contraction, and the nodulated aspect of the fibre
mentioned may have been due to the fact, that the fibre was
not entirely immersed in water (the piece of mica being
merely moistened), but only touched by that fluid at certain
intervals, which most probably corresponded with the
bulgings of the fibre referred to. This explanation is sup-
ported by the effect of water on recent muscular fibre,
entirely immersed in that liquid. Thus, on the moment of
immersion, the fibres contract greatly in length, increase in
a corresponding proportion in bulk, become irregularly bulged
and nodulated: the transverse lines on the fibres disappear,
the longitudinal lines at the same time becoming more
strongly marked than usual. (See Plate XLII. Jig. 3.)
These several effects are due to the extraordinary, unequal,
and doubtless, also, abnormal contraction induced by the
stimulus of water. Presuming, therefore, that in the expe-
riment referred to, the phenomena occur in the order de-

* Physiological Anatomy, pp. 180, 181.

MUSCLE. 349

scribed, yet it would not be safe to adopt the conclusion
from this, that they represent the several stages of the
normal contraction of a muscular fibre. Again, it might be
argued, that the nodular condition described as belonging
to a muscle in a state of active contraction would be most
unfavourable for the full exercise of the power of contrac-
tion, seeing that the nodules of one fibre would necessarily
interfere with those of the contiguous fibres, and thus im-
pede its own as well as their contraction.

For the above reasons, therefore, I would place but little
reliance upon the experiment quoted, and prefer to adopt an
explanation more simple in its character, and yet entirely
sufficient to explain the condition of a muscle during its state
of most active yet entirely normal contraction.

I conceive that no distinct line of demarcation exists
whereby active and passive muscular contraction can be dis-
criminated : the two are but different degrees of the same
power, and manifest themselves by phenomena which differ
not in kind, but simply in extent.

If a muscle of the leg of a frog be isolated from its fel-
lows, or if the tongue of the same animal be extended and
pinned to the margins of an aperture made in a piece of
cork, the only change which can be observed to take place
in the muscular fibre, when stimulated to contraction, consists
in an approximation of its striae, neither waves nor nodules
manifesting themselves in its course.

Again ; immersion of muscular fibre, which has almost lost
its contractile power in water, will be followed by an ap-
proximation of the striae, and a proportionate increase in the
diameter of the filament.

Now, the approximation of the striae is the only visible
sign which I have ever been able to detect in natural mus-
cular contraction ; and it is amply sufficient to account for
the shortening and increase in diameter which a muscle un-
dergoes during its state of most active contraction.

The distance between the stria? in a fibre placed somewhat
on the stretch, as are all muscular fibres in their natural
state, and in that which is in a state of contraction, varies

K E 4

350 THE SOLIDS.

greatly, and is very evident, the strise in the contracted fibre
being often one third or even one half closer together than
they are in the fibre in its ordinary state of tension. The
approximation of the striae to the extent just mentioned, pre-
suming the entire length of the fibres to be in a contracted
condition, would reduce the length of the muscle in the same
proportion, viz. to the extent of a third or even one half.

Muscular contraction, then, I would define to be a simple
shortening of the fibres of a muscle, accompanied by an in-
crease in their breadth ; this shortening in the striped mus-
cular fibre being evinced by an approximation of the trans-
verse striae as well as by an increase in its diameter, while in
the unstriped fibre it is manifested solely by an increase in the
thickness of the fibrillee. (Plate XL1I. fig. 3. «, b.)

Whether, in muscular contraction, the whole length of the
fibres of a muscle is engaged, or part only of their length,
or whether, during the continuance of the contraction of a
muscle, its fibres remain in a state of quiescence ; or whether
they undergo an alternate contraction and relaxation in
obedience to the interrupted stimulus derived through the
medium of the nerves, it is not easy to determine with cer-
tainty ; nevertheless, it is most probable that where the con-
traction is very intense and long sustained; such an alternation
of condition does exist.

The stiffening of the body, which occurs after death, known
by the terms " rigor mortis," " cadaveric rigidity," is due to
muscular contraction. This rigidity usually comes on a few
hours after death ; and after continuing for a variable time,
not exceeding six or seven days, again disappears. There is
much variety, however, in the exact periods of the advent
and departure of the rigidity : it has been observed to come on
latest, attain its greatest intensity, and to last longest in the
bodies of robust persons, who have either died of short and
acute diseases, or who have suffered a violent death. On the
contrary, it has been remarked to set in soonest and to dis-
appear earliest in persons of feeble constitution, and those who
have died of a lingering and exhausting malady.

MUSCLE. 351

The immediate cause of cadaveric rigidity has never yet
been satisfactorily explained. Some have supposed that it de-
pends upon the coagulation of the blood in the capillaries — an
hypothesis scarcely tenable : others, with more reason, con-
ceive that it proceeds from the solidification of the fibrin of
Avhich muscle is chiefly constituted — that it is in fact a phe-
nomenon precisely analogous to the coagulation of the fibrin
of the blood.

An explanation differing from both of the former has sug-
gested itself to my mind. I conceive that muscular con-
traction may possibly be brought about by the stimulus of
the thinner and more watery parts of the blood, &c. acting
on the still irritable muscular fibre, and which are known to
escape from their containing vessels very shortly after the
extinction of life. Of this passage of fluid through the walls
of its receptacle we have a familiar instance in the case of
the gall-bladder and its contents.

Two other points require to be briefly alluded to in rela-
tion to the subject of muscular contraction : the first is the
muscular sound heard on applying the ear to a muscle in
action, and which has been likened by Dr. Wollaston * to
the distant rumbling of carriage wheels : the second relates
to the fact made known by MM. Bequerel and Breschet,
that a muscle during contraction experiences an augmentation
of temperature.

DEVELOPMENT OF MUSCLE.

The muscular tissue, like the majority of those which
have hitherto Been described, takes its origin in cells.

The term fibre is applicable only to the striped form of
muscle in which a number of fibrilla? are included in an in-
vesting sheath common to them : these striped fibrillaj of the
striped fibre of voluntary muscles, are analogous to the un-
Btriped fibrillffi of the involuntary muscles.

The process of the development of muscle may be divided

into three stages : —

Tliil. Trans. 1811.

352 THE SOLIDS.

In the first, isolated cells, arranged in linear series, unite to
form the unstriped fibrilla, the nuclei remaining.

This stage appertains to all unstriped muscular fibre.

In the second, the transverse stria? or markings appear
upon the fibrillse, the nuclei still remaining.

This stage is permanently exemplified in the muscles of the
heart, temporally in the voluntary muscles of the foetus, and
probably also in some few other muscles.

In the third period, the fibrilla become very slender, the
transverse markings more defined, and the nuclei altogether
disappear.

This condition is represented in all the fully developed
striped muscles of animal life.

But the striped voluntary muscular fibre, even of the adult,
constantly exhibits and is constantly passing through the
three stages just described ; a fact not generally known. It
has been ascertained, indeed, since the time of Valentin, that
the striped muscular fibre of the foetus originates in cells,
and also that cell nuclei are contained in each fibre of the
adult ; but it has not been perceived that the fibrillas also pro-
ceed from cells, and that the stage of muscular development,
that of unstriped muscular fibre likewise exists in the vo-
luntary muscles of both the foetus and the adult,

It has been supposed, as we have already seen, that the
nuclei which are met with in the striped muscular fibre are
scattered throughout its entire thickness : this has been shown
to be erroneous, and also that the nuclei are situated only 011
the exterior of each fibre.

Now in every adult striped muscular fibre, we find the
nuclei under the following circumstances : some few of them
are in a free state, others more numerous are contained in
fibrillae, both striped and unstriped: of these fibrillas, the
majority are on the inside of the sarcolemma ; but some of
them are also on its exterior, adhering to its surface, and con-
stituting a considerable part of its substance : lastly, internal
to these nucleated fibrilla? other fibrilla?, which form the chief
bulk of each fibre exist destitute of nuclei.

With a good defining object-glass many of these unstriped

MUSCLE; 353

fibres may be traced for a considerable distance along the
fibre, and may be observed to contain as many as twenty
nuclei.

From these several facts it would thus appear, that striped
and unstriped muscular fibre, do not represent distinct
types of structure, but that each is to be regarded as a dif-
ferent stage in the development of the same. The unstriped
muscular fibrilla passes through but one stage of growth,
and then its development becomes permanently arrested : the
fibrillae of the heart, &c. attain a higher degree of development,
the nucleated fibres becoming marked with transverse striae ;
after which their growth permanently ceases ; lastly, the
striped fibrilla of the voluntary muscles reach the third and
last period in the development of the muscular tissue, having
their nuclei obliterated, and becoming exceedingly slender.

It would appear also that new fibrillae are constantly being
developed, even in the adult muscular fibre.

But certain appearances may be observed which render it
extremely probable that not merely new fibrillae are con-
stantly being developed, but also that new fibres are con-
tinually being formed.

Thus, it is a common thing to meet with unstriped and
even striped fibrillae, which are slightly adherent to the ex-
ternal surface of the sarcolemma; again, small muscular fibres
attached to the larger fibres, and consisting of but very few
fibrillre, may constantly be observed. (Plate XLILjfy. 4.)

In the uterus we have a very remarkable example of a
periodic development and subsequent absorption of unstriped
muscular fibrillae.

The last point to which reference need be made is, to the
doubt expressed as to " whether the identical corpuscles
originally present " (in the fibre) " remain through life, or
whether successive crops advance and decay during the pro-
gress of growth and nutrition." * This matter is no longer
doubtful : the particulars observed in relation to the develop-
ment of muscular fibre enable us to give a solution of the

* Loc. eit. pp. 182, 183.

354 THE SOLIDS.

difficulty. Thus, there is no question but that successive crops
of corpuscles or nuclei are continually being formed in both
the striped and the un striped muscles, and that those in the
former are permanent, whilst in the latter they are only
transitory.

It will be readily perceived that the above detailed views
of the structure and development of the muscular fibre differ,
in very many important particulars from those generally
entertained. According to the views of most physiologists,
the unstriped muscular fibre is the analogue of the striped
fibre ; while, according to those of the author, the striped
fibrilla is the analogue of the unstriped fibrilla, or " fibre" of
most writers. Dr. Carpenter, in the third edition of the
" Principles of Human Physiology," thus clearly gives ex-
pression to the notion that the striped and unstriped muscular
fibres are the analogues of each other. " From the pre-
ceding history, it appears that there is no difference at an
early stage of development between the striated and the non-
striated forms of muscular fibre. Both are simple tubes,
containing a granular matter, in which no definite arrange-
ment can be traced, and presenting enlargements occasioned
by the presence of the nuclei. But whilst the striated fibre
goes on in its development, until the fibrillae, with their
alternation of light and dark spaces are fully produced, the
non- striated retains throughout life its original embryonic
character." The description just quoted, in its application
to thQjfibrillcB of the striped and unstriped muscle, would be
most true, but in its comparison of the unstriped fibrillae with
the entire striped fibre, it is completely at fault.

There is considerable discrepancy between the views en-
tertained by Bowman and Valentin, and those expressed in
this work, in relation to the development of muscle, as will be
evident from the statement of them by the former gentle-
man. " The researches of Valentin and Schwann have
shown that a muscle consists, in the earliest stage, of a
mass of nucleated cells, which first arrange themselves in a
linear series, with more or less regularity, and then unite to
constitute the elementary fibres. As this process of the

MUSCLE. 355

union of the cells is going forward, a deposit of contractile
material gradually takes place within them, commencing on
the inner surface, and advancing towards the centre, till the
whole is solidified. The deposition occurs in granules, which,
as they come into view, are seen to be disposed in the utmost
order, according to the two directions already specified.
These granules or sarcous elements being of the same size as
in the perfect muscle, the transverse stripes resulting from
their opposition are of the same width as in the adult ; but
as they are very few in number, the fibres which they com-
pose are of corresponding tenuity. From the very first
moment of their formation these granules are parts of a mass,
and not independent of one another; for, as soon as solid
matter is deposited in the cells, faint indications of a regular
arrangement in granules are usually to be met with. It is
common for the longitudinal lines to become well defined
before the transverse ones : when both are become strongly
marked, as is always the case at birth, the nuclei of the cells,
which were before visible, disappear from view, being shrouded
by the dark shadows caused by the multitudinous refractions
of the light transmitted through the mass of granules ; but
they can still be shown to exist in the perfect fibre, in all
animals, and at all periods of life, by immersion in a weak
acid ; which, while it swells the fibrous material of the
granules, and obliterates their intervening lines, has no action
on the nuclei."

According to the views entertained by the author, a
striated muscular fibre, in the earliest period of its develop-
ment, consists of cells arranged in linear series : these unite
together, giving origin to the fibrilla and not the fibre, and
that each fibrilla of a fibre is, in like manner, developed from
cells.

Dr. Sharpey, in the fifth edition of Quain's Anatomy, makes
the remark, in treating of the subject of the development of
muscle, ," But much still remains to be explained by future
investigation." The truth of this remark it is conceived is,
in some degree, exemplified in the foregoing article on mus-
cular fibre.

356 THE SOLIDS.

ART. XIX. NERVES.

THE nervous system has been divided into two orders or
lesser systems ; the cerebro-spinal, which includes the brain
and spinal cord, together with the nerves which proceed
therefrom, and the sympathetic systems. The former,
which admits of still further leading divisions, presides over
animal life, its nerves administering to sensation, and being
distributed to the principal organs of locomotion, the muscles,
as well as to those of the senses ; the latter is connected with
the functions of organic life, and supplies principally the
viscera and glands with nerves.

Corresponding with the presumed functional differences of
the two systems, there are also certain structural differences,
the nature of which will shortly be described.

STRUCTURE OF NERVES.

CEREBRO-SPINAL SYSTEM. — The nervous matter consti-
tuting the cerebro-spinal system consists of two very di&tinct
substances, a grey, cineritious, cellular, or secreting structure,
and a white, conducting, or tubular structure.

Secreting or Cellular Structure. — The very numerous situ-
ations in which the grey matter of the brain and spinal cord
is encountered need not here be described at any length : it
will be sufficient to observe, that in the cerebrum it oc-
cupies principally an external situation, a layer of it of
about the one-eighth of an inch in thickness, extending over
the entire surface of its convolutions ; but that it is also
found in lesser quantities in several localities in the interior
of the cerebrum, as in the optic thalami, corpora striata,
tuber cinerium, crura cerebri, &c. ; that on the other hand,
in the cerebellum, pons Varollii, medulla oblongata, and

NERVES. 357

spinal cord it is deep seated, forming the central portion
of these organs.

The secreting substance or grey matter of the brain is
made up of a granular base, in which are contained numerous
nucleated cells of different sizes and forms. In the grey-
matter of the convolutions of the brain the granular base
is very abundant, the cells small and round, and in less
proportion than the base itself: in the tuber cinereum, in the
cerebellum, and in the grey matter of the cord, the small
granular cells are extremely abundant, and the granular
base is diminished in quantity. (See Plate XLV. figs. 2, 3.)

Now the granular base and the small granular cells con-
stitute the principle portion of the substance of the grey
matter wherever encountered : in certain localities, however,
cells of different forms and of considerable magnitude are met
with : these cells have been termed ganglion cells.

Ganglion Cells. — Ganglion cells are encountered in dif-
ferent portions of the cerebro-spinal system, as in the locus
niger of the crura cerebri, in the grey matter of the arbor
vita?, and corpus dentatum of the cerebellum ; in the me-
dulla oblongata ; in the spinal cord for its entire length,
arid according to Valentin and Purkinje, in all the extent
of the cerebral hemispheres, especially in the posterior lobes,
and in the grey lamina of the spiral fold of the cornu
Ammonis.

These cells vary greatly both in size and shape ; many of
them attain a very considerable diameter, and they are,
almost without exception, all provided with caudate pro-
longations, which are frequently branched. (See Plate XLIV.

fig- 4.)

The ganglioniform cells of the locus niger are for the
most part small, and irregularly stelliform in shape : those
of the grey matter of the cerebellum are pyriform, the
spinous and often branched processes, usually two or three
in number, proceeding from their narrow extremities : many
of the cells of the medulla oblongata are triangular, the
spines arising from the angles, and being much produced,

358 THE SOLIDS.

those of the spinal cord are usually very large, irregular in
form, and are furnished with numerous prolongations.

These cells are highly and uniformly granular : they fre-
quently contain pigmentary matter, and enclose a nucleus,
which again is provided with its nucleolus, and both of which
are remarkable for their exceeding brilliancy.

Ganglion cells are doubtless connected with the secretion
of the nervous element or fluid : the use of the prolongations
with which they are furnished, and the precise relation of
these with the adjacent structures, the smaller secreting cells
and the nerve tubules, is not yet well ascertained: it has
been conjectured, however, that the caudiforrn processes are
directly continuous with the tubules ; a view which is
certainly incorrect.

Mixed up with the ganglion cells wherever met with, but
especially with those occurring in the grey matter of the
cerebellum and spinal cord, a considerable number of
branched and nucleated fibres may be seen similar in ap-
pearance and structure to those of unstriped muscle, and
more particularly resembling the gelatinous filaments of the
sympathethic system, from which they in all probability
really proceed.

There is a second description of ganglion cell, not con-
tained in either the brain or spinal cord, but found in the
various ganglia, as the Casserian, Ottic, Opthalmic, Spinal,
&c., formed in connection with the nerves of the cerebro-
spinal and sympathethic systems, and which may be here
described.

These cells resemble the ganglion corpuscles already
noticed in their general structure, but differ from them
in form, being more or less round in shape, and destitute
of the branched processes belonging to the latter. (See
Plate XLV. fig. 4.)

The mode of multiplication of ganglion cells is not well
understood: it is possible that the numerous granules con-
tained in each are the germs of the future cells. Adhering
to the surface of many of the larger ganglion cells of the
second form, a number of nucleated particles or lesser cells

NERVES. 359

may frequently be observed, forming a kind of capsule
around them, which, however, is entirely external to the
proper membrane of the cells. (See Plate XLV. Jig. 4.)

Tubular Structure. — The white fibrous substance of the
brain, spinal cord, the nerves of motion and of special sen-
sation, is composed of unbranched tubules, the diameter
of which is subject to considerable variation. The tubules
of the cerebrum are exceedingly slender, as are also those
of the nerves of special sense : those of the cerebellum,
spinal cord, posterior root of spinal nerves, and of the sym-
pathetic system are of somewhat larger calibre, while those
of the motor nerves are of still larger size, and of firmer
texture. See the figures.

The tubules of the white substance of the cerebrum are
especially prone to become dilated at intervals, or varicose.
(See Plate XLIV.j^. 7.) This condition was formerly sup-
posed to be natural, and it was presumed, that by this cha-
racter the nerves of special sense could be discriminated from
those of motion : there is little doubt, however, but that this
varicose condition of the fibres is abnormal, and that it is pro-
duced by the pressure and disturbance to which they are sub-
ject during examination. The tubules of the cerebellum are
subject to a like change, although in a less degree ; those
of the nerves of motion are but little prone to the altera-
tion, these becoming, when much disturbed, broken into frag-
ments, many of which assume a globular form, and all of
which are greatly corrugated. (See Plate XLIV. Jig. 1.)

The nerve tubules contain a fluid matter, and it is the
collection of this fluid in certain parts of each tubule, the
result of pressure, which occasions the distension of the
membranous wall of the tubes, and which gives rise to the
varicose condition described. Such, is at least, the most
probable explanation of the exact nature of this condition.

The tubules of the cerebrum, cerebellum, spinal cord,
and motor nerves, &c., present an average diameter : never-
theless, much difference may be detected in the size of the
tubules taken from the same portion of the nervous system :

F F

360 THE SOLIDS.

those of the spinal cord agree in their average size with those
of the cerebellum.

The tubes of the cerebrum, of the nerves of special sense,
and of the cerebellum are so small, that it is impossible to
ascertain with certainty the amount of organisation which
really belongs to them : this, however, is not the case with
those of the motor nerves, which are so much larger. (See
Plate XLIV. fig. 1.)

Each tube of a motor nerve consists of an investing
sheath or neurolemma, an inner elastic and but little con-
sistent matter,' the " white substance of Schwann," which
forms a pseudo membrane, and which includes the third
constituent of the nerve tube, a soft and semi-fluid matter,
which, however, would appear in some cases to become solid,
and to exhibit a fibrous fracture: this matter has been
termed the " axis cylinder."

It is a matter of some difficulty to display the investing
sheath, or neurolemma, around the fibres in their fresh and
unaltered state : it may, however, be easily detected, and its
structure recognised in a portion of motor nerve which has
been immersed for some hours in spirit : it will then be seen
that it is made up of nucleated fibres, the nuclei in the
sheath of foetal nerve tubes being of considerable size, and
presenting a smooth aspect. (See Plate XLIV. fig. 2.)

Todd and Bowman describe the outer membrane of the
nerve tube, and to which alone the word neurolemma
should be applied, " as an homogenous and probably elastic
tissue of extreme delicacy, analogous to the sarcolemma
of striped muscle, and, according to our observation, not
presenting any such distinct longitudinal or oblique fibres in
its composition as have been described by some writers."
It will be observed that this description does not accord
with that given by the author.

The white substance of Schwann, on the contrary, is best
seen in the motor nerve tubes, which are perfectly recent,
and which have been but little disturbed : its thickness is in-
dicated by a double line which runs along each side of the
tube : it does not present any trace of organization : it is very

NERVES. 361

clastic, and its contraction gives rise to the corrugated ap-
pearance presented by the tubes of motor nerves which have
been disturbed and broken. (Plate XLIV. Jig. 1.)

The existence of the third constituent of the nerve tube,
the " axis cylinder " of Rosenthal and Purkinje, is best deter-
mined by the immersion of the fibres in either ether or acetic
acid, which breaks it up into granules and vesicles. (Plate
XLIV. fig. 3.)

In albumen the nerve tubes and nervous tissue in general
undergo but little alteration, and it is therefore in this fluid
that its examination is best conducted.

But the tubes of the white fibrous material of the cerebrum,
cerebellum, and spinal marrow just described, form one ele-
ment only of its structure ; another is invariably present,
forming indeed the greater portion of its substance ; and it is
somewhat strange that it should have been overlooked by
observers : this element consists of globules of every possible
size, which, when free from pressure and undisturbed, are
perfectly spherical but which are put out of shape by the
slightest compression or disturbance. It is not easy to de-
termine whether these globules are true cells or not : they pre-
sent the greatest possible variety of size : they have the colour
and consistence of oil ; but nevertheless appear to be hollow,
and frequently present a spot which bears much resemblance
to a nucleus. (See Plate XLIV. Jig. 6.)

It now only remains to be observed, that the nerves of
special sense, as the optic, olfactory and auditory, present a
structure precisely analogous to that of the white substance
of the cerebrum.

SYMPATHETIC SYSTEM. The nerves entering into the
formation of the sympathetic or organic system differ both in
appearance and structure from those derived from the cere-
bro-spinal system : thus the great sympathetic cord itself,
as well as the organic nerves connected with it, present a
reddish grey colour, are soft and gelatinous, and do not
readily admit of division in the longitudinal direction,
although they are easily torn across by any extending
force : these differences of colour and of consistence are de-

362 THE SOLIDS.

pendent upon a difference of structure. The great sympa-
thetic cord itself, and the organic nerves connected with it,
are composed of two distinct descriptions of fibre ; first,
of the ordinary tubular fibre, which, however, is of small
diameter, and therefore readily becomes varicose, and second,
of nucleated filaments, in every appreciable respect resem-
bling those of unstriped muscular fibre. Henle has called
these fibres "gelatinous nerve fibres"

The relative proportions existing between these two kinds
of fibre differs in different nerves: thus in some cases the
gelatinous fibres are by far the most numerous ; in others, the
tubular fibres preponderate. The gelatinons or grey fila-
ments are best seen in what are called the roots of the
sympathetic ; that is to say, in the branches which accom-
panying the carotid artery, proceed from the superior cervical
ganglion to the fifth and sixth pair of cerebral nerves, and
in those which descend from the same ganglion and follow the
course of the carotid. In these the proportion of tubular
fibres is but small, as one to six ; and they are also isolated
from each other, each being surrounded with a number of
gelatinous fibres. This disposition of the nucleated fibres
has led Valentin to consider that they form a sheath around
the tubular fibres, each grey nerve, according to that ob-
server, being composed of a number of fascicles or bundles.
Henle, however, objects to this view, considering that the
fibres are too large for a sheath, and remarking that the grey
nerves do not separate into such bundles, but divide much
more readily in such a way as that the tubular fibre is found
at the border of the bundle. Henle, therefore, considers it
to be more natural to regard the grey nerves as forming solid
threads, composed of nucleated filaments between which the
tubular fibres run.

The tubular fibres are more numerous than in the roots of
the great sympathetic in the majority of the visceral nerves,
in the branches which proceed from the cardiac and hypo-
gastric plexuses, £c. ; in these the tubular fibres may be seen
enclosed within the grey filaments, forming many bundles.
Their number becomes still more considerable in the great

NERVES. 3G3

sympathetic cord itself, and the splanchnic nerves; the cardiac
nerves are almost entirely formed of tubular fibres. In all
these nerves the tubular fibres are observed to be of smaller
diameter than they are in those which are distributed to the
voluntary muscles.

In consequence of the great difference which exists be-
tween the structure of the tubular nerve fibre and that of
the gelatinous nerve fibre, it has been a matter of doubt
with some observers whether the latter should be regarded
as a true nerve fibre or not.

The following is a brief enumeration of the various ana-
tomical and microscopical facts hitherto recorded both in
favour of and opposed to the opinion of the nervous character
of the gelatinous filaments just described.

The chief structural considerations which may be urged in
favour of the opinion that the nucleated filaments associated
with the various nerves of the sympathetic system are true
nerve filaments are —

1st. The origin of the gelatinous filaments from the ganglia
of the sympathetic, as first distinctly affirmed in the researches
of Volkmann and Bidder. *

2nd. The tubular character of these filaments, as shown
by T. Wharton Jones, f

3rd. The periphral distribution of the gelatinous filaments,
as asserted by many observers, but particularly by Bidder,
who even states that he succeeded in counting their number
in the transparent septum of the auricles of the frog's heart.

4th. The peculiar structure of the ganglion caecum, dis-
covered by Mr. T. Wharton Jones, in connexion with one
of the ciliary nerves of the dog. J

5th. The variable yet fixed proportions of gelatinous and
tubular fibres occurring in different nerves, as described
especially by Henle.

6th. The occurrence, as stated by Todd and Bowman, of

* Die Selbstandigkeit ties Sympathisken Nervensystems durch Ana-
tomische Untersucliungen nachgewiesen Von J. H. Bidder und A. W.
Volkmann. Leipsig, 1842.

f Lancet, April 24th, 1847. J Lancet, November 14th, 1846.

tt G

364 THE SOLIDS.

nucleated filaments very similar to the gelatinous fibres of
the sympathetic " in parts where their nervous character is
indubitable, as in the olfactory filaments, and the nerve in
the axis of the Pacinian corpuscle exhibits very much the
same appearance save that it is devoid of nuclei," *

7th. The resemblance borne, according to the observations
of Schwann f , between the tubular nerve fibre in the early
stages of its development, in which it is described as being
nucleated, and the adult gelatinous fibre.

8th. The origin of the gelatinous filaments from the cells
themselves composing the ganglia of the sympathetic, as the
observations of several observers tend to prove.

These various facts thus briefly referred to, could they all
be fully depended upon, would, doubtless, make out not
merely a strong, but even a convincing and unanswerable
case in favour of the nervous character of the gelatinous fila-
ments : unfortunately, however, those facts, which, if they
could be relied upon, would be the most conclusive, are open
to question : such, for instance, as the periphral distribution
of the gelatinous filaments, their presumed origin from the
ganglionic corpuscles, and the asserted resemblance between
the tubular nerve fibre in an early stage of its development
and the fully grown gelatinous filament ; it will presently be
shown, indeed, in the observations on the growth of the
primitive nerve tubule that no such resemblance exists.

Subtracting then the points referred to in the 3rd, 7th,
and 8th headings, no one conclusive fact remains of the posi-
tion that the gelatinous fibres are really nervous.

Against the opinion that the gelatinous filaments are
nervous, may be urged —

1st. The positive structural identity between the gelatinous
nerve filament and the fibrilla of unstriped muscle, and the
great improbability, as a consequence, that one and the same
structure should have to perform two such distinct functions
as must necessarily belong to a muscular fibre and a nerve
tube.

* Physiological Anatomy, part iii. p. 142.

-j- See Wagner's Physiology, translation by Willis.

NERVES. 365

2nd. The apparent structural unfitness of nucleated fila-
ments to serve as a conducting medium of the nervous force.

3rd. The evidently tubular character of the nerve filaments
in parts which, from their nature, we should expect would be
pre-eminently supplied by the gelatinous filaments.

4th. The fact of the non-occurrence of gelatinous fibres,
separate from the tubular, is strongly opposed to the idea of
the independence of the former.

The above short summary will serve to give some idea of
the state of the much canvassed question of the nervous or
non-nervous character of the grey or gelatinous filaments of
the sympathetic.

STRUCTURE OF GANGLIA.

The ganglia consist of the peculiar globules already de-
scribed, of nerve tubules and of gelatinous filaments.

Each ganglion is enclosed in an investing tunic of fibrous
tissue, a continuation of the common envelope of the nerves
which enter and depart from it, and which sends down dis-
sepiments which divide the contained globules into parcels,
and thereby give the ganglion the general arrangement and
character of a gland.

The gelatinous nerve filaments in the ganglion form a kind
of inner capsule, and their arrangement is thus described by
Henle : " Besides the nervous fibres properly so called of the
soft nerves, one meets with also, in the ganglions of the great
sympathetic gelatinous fibres which have special relations
with the ganglionic globules. The fibres of a bundle expand
in the form of a funnel, in order to embrace a globule or a
series of globules, and unite together afterwards afresh, to
separate again a second time. In this way we often come
to draw out of a ganglion entire threads of gelatinous fibres,
which are dilated, in the manner of a chain of pearls, and
enclosing the globules in their dilatations."

The proper tubular fibres enter the divisions of the gan-
glion in bundles, subsequently separate from each other,

c G 2

366 THE SOLIDS.

and ramify amongst the ganglion globules in a waved and
serpentine manner.

The arrangement of the ganglion globules and nerve
tubules just indicated, tends to show that these are really
the only essential elements of a ganglion.

The ganglia are supplied with blood-vessels.

It will be apparent from the above description that the
ganglia have all the structural characteristics of glands, and
therefore there can be little question but that they are really
glandular organs, and that the tubular fibres which pass
through them carry away the fluid, which is destined to
exercise its influence on the parts and organs to which the
nerves are themselves distributed.

The question as to the origin of either the tubular fibre or
the gelatinous filament from the ganglionary corpuscles,
is still an undecided one, the weight of evidence being op-
posed to the idea, that either order of fibres has any origin
from these corpuscles.

ORIGIN AND TERMINATION OF NERVES.

Origin. But little that is certain is known respecting the
exact mode of origin of the numerous tubules composing the
nerves, and of the precise relation of these with the cellular
or secreting element of the ganglionic centres. The obser-
vations of Dr. Lonsdale *, however, render it highly probable
that the greater portion at least of the nerve tubes have a
looped origin in the brain and spinal cord : that gentleman
having made out the interesting fact, that in two foetuses, in
the one of which both the brain and spinal cord were deficient,
and in the other the brain only, the extremities of the nerves,
which extended into the cavities of the spinal column and
cranium were made up of looped nerve tubes imbedded in an
imperfectly developed granular and cellular matter, apparently
of a ganglionic character. Now, from what is known re-

* Edinburgh Medical and Surgical Journal, No. cxvii.

NEKVES. 367

specting the laws of development, it would appear to be a
perfectly justifiable and natural inference, that the nerve
tubes, when fully developed, have a similar mode of origin.

According to some observers, certain nerve tubes are con-
nected with and take their origin from the prolongations with
which the* caudate variety of ganglionary cells are provided :
this view, however, is confidently denied by many other in-
vestigators, and the point is one which is still involved in
considerable uncertainty : for myself I would observe, that I
have never succeeded in making a single observation favour-
able to such a conclusion. Notwithstanding, however, the
doubts which are now entertained respecting the modes of
origin of nerve tubes, the question is assuredly one which, at
some future day, will be satisfactorily determined by direct
observation.

It is also still uncertain, whether nerve tubules originate in
the ganglia not included in the brain, as in those connected
with the encephalic nerves, and those of the sympathetic
system.

When speaking in the preceding remarks of the origin
of nerves, that extremity of them is implied which is in con-
nexion with the brain and spinal cord : it is questionable,
however, in the case of the nerves of special sense, whether it
would not be more proper to consider their periphral rather
than their central extremities as their true origins ; a view
supported by the consideration that the sensations arise in, and
proceed from, the organs of the senses inwards towards the
brain, the great centre of nervous structure and force, as well
as by the fact, that the periphral extremities of these nerves
are generally, if not invariably, connected with ganglionic
cells ; such an association of the two elements is known to
exist in the eye, in the ear, in the nose, and probably exists
also in the papilla of the tongue and skin.

Termination. It was not known until within the last four
or fiv,e years that nerves had any real termination : it was up
to that time generally considered that the nerve tubes in-
variably ended in the same manner as it is now supposed
that they originate, viz. in loops, and there can be little

G C 3

368 THE SOLIDS.

question but that such a mode of termination, though not
universal, is at least very frequent : thus, the arrangement of
the primitive nerve fibres in loops has been described by
Valentin, in the pulps of the teeth ; by Miiller, in the mem-
brana nictitans, and in the mucous membrane of the throat
of the frog ; in the papilla? of the skin and tongue, by Todd
and Bowman. The loops are formed by one or more of
the nerve tubes, separating themselves from the bundle of
tubes composing every nerve of any magnitude, and after-
wards either passing into and mingling with those of a
neighbouring nerve, or else returning back to that from which
originally it started.

It is now, however, very certain, that some at least of the
nerve tubes have a real termination : this is indisputably the
case with the single filaments which enter the Pacinian
bodies ; it has also been shown to occur with many of the
primitive tubes distributed to muscles.

PACINIAN BODIES.*

The Pacinian bodies are found in considerable numbers
attached to the cutaneous nerves of the hands and feet, espe-
cially to those of the extremities of the fingers and toes;
they are also met with, though more sparingly, on other
spinal nerves, on the plexuses of the sympathetic, but never
on the nerves of motion, and in the mesentary ; in that of the
human subject, however, they are only with great difficulty
to be discovered owing to its thickness and the quantity of
fat usually contained in it : in the mesentary of the smaller
mammalia, as the cat, rabbit, &c. and more particularly
when these are in a lean state, they may be readily dis-

* The discovery of these remarkable bodies constitutes one of the
happiest and most beautiful results of the application of the microscope
to minute anatomy. Pacini first noticed them in 1830, subsequently in
1835 ; but it was not until 1840 that he gave an account of them. (Nuovi
organi scoperti nel Corpo umano dal Dott Filippo Pacini, Pistoja). A. G.
Andral, Camus, and Lacroix, announced their existence at a Concours at
Paris in 1833, but do not appear to have recognized their real character.

NERVES. 369

cerned with the naked eye^ and the entire of their structure
followed out without even the employment of a reagent : it
is therefore in these animals that they are studied to most
advantage.

The Pacinian bodies vary greatly in size, but are usually
as large as the head of a pin of ordinary magnitude ; they
are of an oval or pyriform shape, are perfectly translucent,
attached to the nerve filaments by short pedicels, and occur
either singly or sometimes in pairs. (See Plate XL VI.
fig. 1.

So large are these peculiar bodies that the whole of their
structure may be followed out with object glasses of an inch
and half- inch foci; when examined with these magnifying
powers each Pacinian body is observed to consist of nu-
merous concentric lamellae or capsules disposed with much
regularity ; these lamella are formed of white fibrous tissue,
contain numerous nuclei in their substance, and are separated
from each other by distinct intervals which contain fluid;
the spaces intervening between the plates do not commu-
nicate and diminish gradually but regularly from without in-
wards, so that the central lamellae are almost in contact with
each other, from which cause they present a darker aspect
than do those having appreciable spaces dividing them the one
from the other : these capsules have been distinguished from
the rest by the term the " inner system of capsules." It is
this regular disposition of the lamella? together with their
gradual approximation which imparts so beautiful an ap-
pearance to these strangely constituted organs. The cap-
sules, however, are not continued to the very centre of the
Pacinian body ; but in that situation a cavity, having a
somewhat elliptical form and filled with fluid exists. This
cavity opens externally by means of a canal which pierces the
whole of the lamellae and the sides of which canal are formed
by the union of those lamellae : into this canal a single nerve
tube passes, enters the central cavity just described, which it
traverses from end to end in a straight line, terminating in a
slightly enlarged extremity, which is described as being at-
tached to the inner wall of the distal end of the central cham-

oo4

370 THE SOLIDS.

ber; the nerve tube, immediately on its entrance into this
chamber, loses its double and defined border, in consequence,
it is presumed, of the absence of the white substance of
Schwann. (Plate XLVI.jfy*. 2, 3.)

Such is a brief and general description of the Pacinian
body ; one or two other points of a less evident character still
remain to be noticed. It has been stated that the capsules
contain elongated nuclei in their parietes, that they are formed
of fibrous tissue, and that the spaces between them have no
communication with each other: if the outer and larger capsules
be carefully examined it will frequently be observed that they
present a double edge separated by a faint interval, and con-
veying the impression that each capsule is made up of two
distinct membranes : it is in this interval that the nuclei are
lodged : that the inter-capsukr spaces do not communicate
with each other is proved by the fact that when the outer
capsules are pierced through, the fluid escapes only from the
spaces which have been opened into; if the whole of the cap-
sules have been divided the entire corpuscle immediately col-
lapses. (It is a curious fact that a Pacinian body allowed to
dry up does not again absorb fluid and expand to its natural
size.) It has also been observed that the capsules are united
to each other at the proximate extremity of the Pacinian
body along the sides of the canal already described : according
to Pacini they are also bound together at the distal end by a
band of fibrous tissue, which he calls the " intercapsular liga-
ment : " the existence of this ligament has been denied by
Henle and Koelliker.* Todd and Bowman do not deny its
existence, but state that they have seldom seen it reach the
surface of the corpuscle, f

Pacinian bodies not unfrequently present varieties of form
and structure : it is possible that many of these admit of ex-
planation on the supposition that in some instances they are
multiplied by self -division : thus sometimes the distal end of

* Ueber die Pacinischen Korperchen an den Nerven des Menschen
iind der Saugethiere, Zurich, 1844.
' f Physiological Anatomy, vol. i. p. 397.

NERVJUS. 371

the central chamber is bifid, the nerve tube being also
divided ; in others a single corpuscle will be found to contain
two distinct chambers and nerve tubes, each being surrounded
by a certain number of capsules, but which again are them-
selves included in a number of other capsules which embrace
both the sets of inner membranes : again, in other instances,
two Pacinian corpuscles, entirely formed, but yet not alto-
gether separated from each other, being connected by a few
of the capsules will be situated upon a single primitive nerve
tube : a fourth peculiarity, which may be noticed more fre-
quently than any of the others, is the curling back of the
extremity of the central chamber, the innermost capsules
describing the same curvature. (See Plate XL VI. ,/^s. 4, 5.)

DEVELOPMENT AND REGENERATION OF NERVOUS TISSUE.

Development of nerve fibres. — The following is the account
given by Schwann of the development of the nervous cords
as rendered by Willis in his translation of Wagner's Phy-
siology, the references to the figures only being omitted.
" The nerves appear to be formed after the same manner as
the muscles, viz. by the fusion of a number of primary cells
arranged in rows into a secondary cell. The primary ner-
vous cell, however, has not yet been seen with perfect pre-
cision, by reason of the difficulty of distinguishing nervous
cells whilst 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 multi-
tude of nuclei are apparent. It is easy to detach individual

filaments from a cord of this kind, in the interior

of which many nuclei are included, similar to those of the
primitive muscular fasciculus, but at a greater distance from
one another. The filaments are pale, granulated, and (as
appears by their farther development) hollow. At this
period, as in muscle, a secondary deposit takes place upon
the inner aspect of the cell membrane of the secondary ner-

372 THE SOLIDS.

vous cell. This secondary deposit is a fatty white-coloured
substance, and it is through this that the nerve acquires
its opacity. With the advance of the secondary deposit,
the fibrils become so thick, that the double outline of their
parietes comes into view, and they acquire a tubular appear-
ance. On the occurrence of this secondary deposit the nuclei
of the cells are generally absorbed ; yet a few may still be
found to remain for some time longer, when they are observed
lying outwardly between the deposited substance and the cell
membrane, as in the muscles. The remaining cavity appears
to be filled by a pretty consistent substance, the band of
Remak, and discovered by him. In the adult, a nerve, con-
sequently, consists, 1st, of an outer pale thin cell membrane —
the membrane of the original constituent cells, which becomes
visible when the white substance is destroyed by degrees ;
2nd, of a white fatty substance deposited on the inner aspect
of the cell membrane, and of greater or less thickness ; 3d, of
a substance, which is frequently firm or consistent, included
within the cells, the band of Remak."

The author's observations lead him to entertain views of
the development of the primitive nerve tube essentially dis-
tinct from those expressed by Schwann in the account quoted
above: according to these observations, the outer covering
of the nerve tube does not consist of a structureless membrane,
as is supposed by Schwann, as well as most other observers,
but is constituted of a nucleated form of fibrous tissue. (See
Plate XLIV.^. 2.) Now, the nuclei observed by Schwann
the author believes to be concerned in the development of the
fibres, of which the proper membrane of each primitive nerve
tube is wholly constituted, and that they do not by their
orowth give origin to a transparent tubular membrane.

In the nerve tubes of both young and adult animals,
smooth bodies of an oval form and large size, their diameter
exceeding that of the tube itself, may always be observed ;
the nature of these, and the part taken by them in the struc-
ture and development of the nerve tube, I have not been able
to determine.

Development of Glandular Nerve or Ganylionary Cells. — The

NERVES. 373

nervous matter composing the two or three systems into
which, in the present day, it is divided, presents all the
essential and distinctive characters of a true gland, so that its
description would have been more correctly given under the
general heading of " Glands."

The nerve or ganglionary cells present essentially the same
structure as all other glandular cells, and are doubtless con-
tinually passing through the same phases of development and
destruction during the progress of nutrition and secretion.

The secreting or glandular cells in the brain and spinal
marrow, are for the most part aggregated into distinct
masses, the term ganglia being equally applicable to these
masses as it is to those existing in connexion with the
nerves of the sympathetic system. Henle considers that the
principal development of new cells takes place on the outer
surface of the brain, which is the most vascular from its con-
tiguity to the pia mater, and that the more mature cells are
gradually conveyed inwards, coming thus into nearer con-
nexion with the tubular or conducting fibres, the disin-
tegration and removal of the older cells determining the
movement of the cells from without inwards. This view, as
applied to the grey matter of the convolutions of the brain
is probably correct, and is to some extent confirmed by an
observation which I made several months since, viz. that the
cortical substance of the cerebellum consists of two distinct
portions separated by a well-defined line, perceptible with a
common magnifying glass : the outer portion is made up of a
granular base, containing but few fully developed cells, while
the inner portion consists almost entirely of completely formed
cells. The distinct separation of the cortical or secreting
matter of the cerebellum into two portions is very remarkable,
and the purpose fulfilled by such an arrangement wholly
obscure.

Regeneration of Nervous Matter. — The regeneration of the
primitive nerve tube admits of proof, both by experiment
and direct observation. The experimental proof consists in
the simple division of nerves, and even in the removal of
portions of them : the parts to which the nerve is distributed,

374 THE SOLIDS.

of course at first, lose their sensory and motor endowments :
these, however, after a variable time, are more or less per-
fectly recovered, thus completing the experimental proof.
The direct proof is derived from the former : the recovery of
the power of a nerve after the excision of a portion of it,
argues strongly the fact of the regeneration of tlie nerve
tubes ; and this result, by a careful microscopic examination,
can be positively demonstrated : the number of tubes in the
renewed part of the nerve is stated, however, to be less than
in the original portions ; and this in part explains the reason
of the restoration of the functions of a divided nerve being
usually but imperfect. Other proofs of the regeneration of
the nerve tubes may be gathered from the more or less complete
restoration of various sensitive and motor parts of the body,
as well as from the re-union of parts which have been en-
tirely detached from the body, as the nose, the top of the
finger, &c.

With respect to the regeneration of the glandular element
of the nervous matter, but little definite or microscopic is
known: from analogy, however, it may be inferred, that
like other cellular structures, as the epidermis, epithelium,
&c. it also is capable of a more or less complete repro-
duction.

RESEARCHES OF M. ROBIN.

The following is a translation of an abstract made by the
author himself, M. C. Robin, of a paper communicated to the
Royal Academy of Sciences at the Seance of June 21st,
1847, entitled " Researches on the Two Orders of Elemen-
tary Nerve Tubes and the Two Orders of Ganglionary Glo-
bules which correspond to them."

" The end of these researches is to show that tlTe ganglions
of the spinal nerves and of the great sympathetic do not give
origin to elementary nerve tubes as many modern anatomists
admit, as Hannover, Valentin, Remak, Bidder, and Volk-
mann, &c., &c. ; but- that all the nerve tubes arise exclusively
from the spinal cord and the encephalon ; consequently that

NERVES. 375

one can only regard these ganglions as special little nervous
centres performing, with respect to certain functions, the
same office as does the cerebro- spinal centre for the other
functions. These reflections naturally occur to the mind
when one sees the cavity of the tubes or elementary nerve-
fibres given off from the spinal cord, or from the encephalon,
merge into the cavity of the ganglionary globules at one of
their poles, and reappear at the opposite pole of the globule
in the same manner that they entered.

" Setting out from a globule (cell) these nerve tubes pro-
ceed to lose themselves in the organs. Thus, those peculiar
cells, the agglomeration of which constitutes the ganglions of
nerves, are no other than organs which are interposed be-
tween the origin of the nerve tube and its termination at a
determined point of its course, and, perhaps, there is more
than one upon each fcube : they interrupt it in its course to
allow it once more to reappear ; they change it, they modify
its structure at a point to immediately restore it.

" The authors who have hitherto written upon the subject
have not observed the entrance and exit of each elementary
tube at the two opposite poles of each globule, but only the
one or the other. It is this circumstance which has led them to
consider each of these ganglionary globules as a little nervous
centre of origin for each tube.

" There is yet another fact still more important than the
first, which has not been pointed out by anatomists who have
studied the structure of nerves.

" They have all described but one order of globules : there
are, nevertheless, two which differ, the one from the other, in
numerous characters, deduced from the consideration of size,
form, contents, walls, &c. One of these orders of globules is
always in ^connexion with the elementary nerve tubes of
animal life or the large tubes, &c. The other is associated
especially with the elementary tubes of organic or sympathetic
life, or with the small tubes, &c. One never finds the large
tubes communicating with the second order of globules, and
reciprocally the small tubes are never in connexion with the
poles of the globules of the first order.

376 THE SOLIDS.

" It follows from these facts, that one can no longer doubt
the existence of the two orders (altogether extinct) of ele-
mentary nerve tubes named above, which, nevertheless, some
authors have done recently. (Kolliker.)

" The two orders of globules, and of the corresponding
tubes, exist in the posterior or sensitive roots of the nerves of
the spinal cord, but the globules do not exist in the anterior
or motor roots.

" They exist also in the ganglions of the encephalic nerves
and of the great sympathetic ; only in these last there is a
much greater number of globules and of slender tubes than
of globules and of large tubes (thirty or fifty to one), more
or less according to the ganglions. In the spinal ganglions, on
the contrary, there are about four or five globules and large
tubes to one of the other kind.

e( These facts tend to confirm the Observations of ana-
tomists who have pointed out the existence of the two orders
of elementary tubes in the nerves of animal life and those of
the great sympathetic, but with predominance of the large
tubes in the first, and of the slender tubes in the second ; not-
withstanding which no one of them has pointed out the ex-
istence and the difference of the two orders of ganglionary
globules.

" The absence of ganglionary globules on the anterior or
motor roots of the spinal nerves anatomically distinguishes
the elementary tubes of motor nerves of animal life from
those of the sensitive nerves. But this decisive character
can be remarked only in the short course of the roots of the
spinal nerves before their union and the mixture of their
tubes. If wishing to push still further the deductions to be
drawn from the preceding facts, we demand of ourselves
what functions should be attributed to the ganglionary
globules, we should answer, that they are the modifiers of
the action which takes place in the sensitive and in the or-
ganic nerves ; but it is impossible to determine the nature of
this modification.

" Since the ganglia of the sympathetic and of the cerebro
spinal nerves enclose the same ganglionary globules and the

NEKVES. 377

same elementary tubes, but only in different proportions, we
see that we cannot with Reil, Bichat, &c. acknowledge two
nervous systems independent of each other. This opinion is
founded on the communications of the great sympathetic with
the spinal nerves ; on the fact of nerves being furnished to
the abdominal diaphragm of birds, exclusively by the great
sympathetic (Sappey) on the partial and successive substitu-
tion of sympathetic nerves for spinal and encephalic in a great
many vertebrata."

The above highly interesting observations of M. Robin
need confirmation, and it is to be hoped that microscopic ana-
tomists will direct their attention to the subject. In the
many examinations which I have made of ganglia, I have
never recognised the presence of two orders of ganglionary
cells, nor have I ever perceived any attachment between the
tubes and cells. I would remark, however, that I have made
no examination of the ganglia and their constituent cells
since the publication of the researches of M. Robin. There
is one defect in the abstract of the author, of which we have
given a somewhat literal translation, viz. that the distinctive
characters of the two orders of ganglionary cells are not
recited : it will be observed also that no mention is made of
their occurrence in either the brain or spinal cord : from this
I should judge that M. Robin was not acquainted with the
delicate cells described by me in Part X. of this work, as
existing in vast numbers in the white substance of the cere-
bum, cerebellum, spinal cord, and nerves of special sense
wherever this occurs.

378 THE SOLIDS.

ART. XX. ORGANS OF RESPIRATION.

THE organs of respiration seem to stand alone in the animal
economy, and not to exhibit any strong structural relation-
ship or affinity with any other organ or organs comprised in
that economy. In their position and general form they bear
some resemblance, in the mammalia at least, to glands : this
resemblance, however, is more apparent than real, as becomes
evident from the single consideration that the lungs are es-
sentially destitute of the innumerable granular cells which
constitute the chief bulk of true glands and form their dis-
tinctive and essential element. In a strictly natural ar-
rangement the lungs would be more properly and correctly
described in connexion with the circulatory apparatus ; for
essentially they are vascular organs, their only indispensable
constituent being blood-vessels, so situated indeed as to admit
of their being brought continually into contact either with
air, or with water impregnated with air.

The great object aimed at in the formation of the lungs
of mammalia is the construction of organs which shall occupy
but little comparative space, and which shall yet present a
greatly extended surface, throughout which the blood and
air may be brought into close approximation. We shall now
proceed to describe the manner in which this purpose is ac-
complished.

The tissue of the lungs of man and other mammalia may
be divided into two systems of apparatus : the first comprises
the circulatory or vascular apparatus, consisting of arteries
and veins together with the plexuses formed by the union of
the capillaries proceeding from both sets of vessels ; the
second comprises the respiratory or aeriferous system, which
includes the bronchial tubes, the air cells and the ciliated
epithelium. The intimate structure of the lungs will be best
understood by an examination in the first place of the aeri-
ferous apparatus.

ORGANS OF RESPIRATION. 379

AERTFEROUS APPARATUS.

The aeriferous apparatus of the lungs consists of bronchial
tubes and air cells.

Bronchial Tubes. — The bronchial tubes are formed
of cartilaginous rings united by - elastic tissue : the rings,
however, are imperfect, and are only present in the larger
tubes, as those of the first, second, and third or fourth dia-
meters : in the smaller tubes they are absent, these being-
composed entirely of a nucleated form of fibro -elastic tissue :
they divide repeatedly in a dichotomous manner : it is not
easy, however, to determine the number of divisions which
each bronchial tube undergoes after its entrance into each
lobule : it would appear, however, that the intra-lobular
ramifications are less numerous than the interlobular branch-
ings, the bulk of the lobule consisting chiefly of air cells.

The bronchial tubes are lined throughout by mucous mem-
brane, which is invested by a stratum of cylinder ciliated
epithelium. The smaller bronchial tubes are eminently elastic
and contractile by virtue principally of the elastic tissue of
which they are chiefly formed. This elasticity is still fur-
ther increased in the case of the larger tubes by the presence
of muscular fibrilke of the unstriped kind.

Air cells. — The air cells are minute cavities of variable
size, of an angular form, not dilated, which communicate
freely with each other and the parieties of Avhich are formed
of a diaphanous, tough, highly elastic and delicately fibrous
membrane, which contains and supports the capillary blood-
vessels, and the interior of which is lined by a modified
mucous membrane also invested with a layer of ciliated epi-
thelium.

From this description, it becomes evident that the air cells
contain the same structural elements as the smaller bronchial
tubes- themselves, and that they therefore differ from these
solely in form and arrangement, possessing precisely the same
general physical properties, being in the same manner highly
elastic, a property mainly dependent upon the abundance

H H

380 THE SOLIDS.

of fibre-elastic tissue present in the lungs. (See Plates
XL VII. and XLVIIL)

That the air cells do really communicate freely with each
other (a fact which is now generally admitted, but which is
yet denied by Dr. T. Williams*) may be satisfactorily deter-
mined in many ways. Thus it is by no means difficult to see
the circular and ever patent openings of communication, both
in injected and uninjected lungs ; again, by injection with size,
perfect casts of the cells may be obtained : these casts when
a fragment of lung is torn up in water, readily escape, by
which means the variety presented by the cells in form and
magnitude may be accurately determined, as well as the shape
and number of the openings of communication. (See Plate
XL VIII. fig. 2.) Not unfrequently these casts are more or
less coated with the epithelium lining the cells, as also repre-
sented in the figure just referred to.

So perfect and consistent are the models of the air cells
procured in this way, that for some time I was led to enter-
tain the idea that each little mass of size was really enclosed
in a delicate and structureless membrane, which I conceived
to be the true air cell lining, and I have scarcely yet been
able to discard the notion altogether from my mind. If the
lung be injected with tallow, we do not procure casts in the
same number and perfection, because the tallow adheres
closely to the sides of the air cells. Sometimes I have seen
casts even without injection ; but the occurrence of these is
rare. It is, therefore, yet possible that I have not been
deceived, and that a structureless membrane does really line
the air cells, a modification of the mucous lining of the
tubes, the " basement membrane " of Bowman.

It would appear from an examination of these casts, that
the number of openings of communication varies from one
to five ; usually, however, but one, two, or three are present.

When looking attentively at these casts, covered with

? * Essay on the Structure and Functions of the Lungs. College of
Surgeons, London, 1842.

ORGANS OF HESPIEATIOX. 381

epithelial cells, and labouring under the impression that they
were really distinct structures, I have sometimes perceived
cells of glandular epithelium, one much larger than the rest,
with a transparent border ; and this I fancied was a fresh cell
membrane in process of development.

The presence of epithelial scales in the air cells was first
observed by Mr. Addison*; but that gentleman was unable
to determine whether these were ciliated or not; subse-
quently Mr. Rainey f advanced the statement that healthy air
cells contain no epithelium. In sections of recent lungs, it
is a very easy matter not merely to determine the existence
of epithelium in the air cells, but also the fact of its cylinder
and ciliated form and character. Circular and oval epithelial
cells also occur : these are most probably ciliated cells in a less
advanced condition of development. (See Plate XL VIII.
Jig. 3. and Plate XLIX. fig. 2.)

It has been stated that the air cells vary in size. This is the
case with even contiguous cells, as may be seen by a re-
ference to the figures : the air cells in the lungs of an adult
are also much larger than those of a child.

The fact of the epithelium extending from the bronchial
tubes into the air cells, would seem in itself to imply that
the mucous membrane also lined them, at least in a modi-
fied condition, which is contrary to the opinion expressed by
Mr. Rainey.

VASCULAR APPARATUS.

The vascular apparatus of the lungs consists of arteries
and veins : these vessels, after numerous ramifications in the
interlobular spaces, unite together on the surface of the air

* Observations on the Anatomy of the Lungs, by Thomas Addison,
MD., 1841. Transactions, Medico-Chirurgic Society.

f On the Minute Structure of the Lungs, and on the Formation of
Pulmonary Tubercle, by George Rainey. Transactions, Medico-Chirurgic
Society, 1845.

H H 2

382 THE SOLIDS.

v cells, through the medium of a beautiful and elaborate system
of plexuses, each air cell being furnished with its own sepa-
rate plexus.

The manner in which the vessels, either arteries or veins,
are distributed throughout each lobule is as follows : — first,
large branches, after having reached the lobule through the
interlobular spaces, extend over an area of several cells (See
Plate XL VII. Jig. 2) ; from these, secondly, a number of
smaller vessels proceed, which run in the spaces between
the cells, forming loops around them (See Plate XL VII.
Jig. 3) ; third and last, from these intercellular vessels the
capillaries constituting the plexuses are given off. (See
Plate XLIX. Jig. 3.) This distribution of the vessels is
especially evident on the pleural surface of the lung.

From the preceding description it does not appear that
the capillary plexus belonging to each air cell is compounded
of both venous and arterial capillaries, but that in most cases
it consists entirely of capillaries derived exclusively either
from a vein or an artery.

It is thus evident that an air cell with its investing plexus
of capillaries contains all the essential constituents of an en-
tire lung, and therefore that each air cell may be regarded as
a lung in miniature.

It is well known that it is frequently a matter of great
moment, in a medico legal respect, to discriminate between a
lung naturally inflated and one artificially so : the test pro-
posed and ordinarily employed and relied upon, seems to me
to be unworthy of full confidence. I allude to the hydrostatic
test : it is stated that, by firm pressure, all the air contained
in a portion of lung artificially inflated may be expressed, so
that it will sink in water ; but that this cannot be done in
the case of a lung naturally inflated ; a portion of air will
always remain unexpressed sufficient to keep it afloat. I see
no good reason for this constant difference, since it is perfectly
certain that a lung may be most completely and entirely in-
jected with air or fluid, far more completely, I should be in-
clined to say, than occurs with air naturally inspired, except
perhaps during a forced inspiration. Notwithstanding the

ORGANS OF RESPIRATION. 383

uncertainty which seems to me to be attached to this test,
I yet consider that by a careful examination of the con-
dition of the blood vessels in the two lungs, the question
may in most cases be satisfactorily determined, whether has
the lung been artificially or naturally extended with air ?

Previous to birth, it is known that the circulation of blood
through the lungs is of a very limited character, and that it
is only after that period, and during the first act or acts of
respiration that the great mass of vessels, principally capil-
laries, become carriers of blood.

The vessels then, in the one case, viz. before respiration,
will be almost devoid of blood, and, in the other, after that
act, replete with that fluid.

Dependent upon this difference in the condition of the
vessels, we shall notice certain distinctive features, both
general and microscopical, in the case of the artificially and
the naturally inflated lung. The former, after inflation, will
be observed to collapse to nearly its previous size on the
escape of the air ; it will present a pale appearance, especially
evident if the lung be cut into, and when examined with a
lens, it will be seen that the interspaces between the lobules
and cells are pale, not being occupied with red vessels. Now,
on the other hand, the latter will be characterized by appear-
ances the very reverse : it, after inflation, will not collapse to
nearly its previous size ; it will be somewhat red, and the in-
tervals between the lobules and cells will be seen to contain
red vessels, in which, as well as in the capillaries, the higher
powers of the microscope will reveal the existence of red
blood discs.

PATHOLOGY*

Now that the normal anatomy of the lungs is well under-
stood, the several pathological conditions of those organs
admit of a precise and satisfactory explanation. The prin-
cipal diseases of the lungs, upon the exact nature and seat of
which the microscope affords, directly or indirectly, satisfac-

H II 3

384 THE SOLIDS.

tory information, are Emphysema, Asthma, Pulmonary'Apo-
plexy, Pneumonia, and Tubercle.

Emphysema. — The essential pathological and microscopical
characters of Emphysema consist in an enlargement and rup-
ture of a greater or less number of air cells, whereby the
cavities of several distinct cells become thrown into one, with
sometimes tho, escape of air from the ruptured air cells into
the interlobular cellular tissue. When the air cells are sim-
ply dilated and ruptured, without any escape of air from
them, the Emphysema is lobular; when, on the contrary, the
air passes from the cells into the cellular tissue, which unites
the lobules to each other, the Emphysema is termed inter-
lobular. It cannot be doubted but that this condition of the
lungs interferes very greatly with the efficiency of these
organs ; the extent of surface over which the air and blood
are brought into contact being very considerably diminished.

Asthma. — The microscope has revealed the fact that the
smaller bronchial tubes and air cells are principally consti-
tuted of a form of elastic tissue, which, possessing marked
physical properties, is yet, to a certain extent, under the
control of the nervous system. It is then the irregular
action and contraction of this tissue, determined partly by
physical causes and partly by irregular and unequal impres-
sions arising from internal causes conveyed to this tissue by
the nerves, which occasion and account for the distressing
and peculiar symptoms of Asthma.

Pulmonary Apoplexy. — Pulmonary apoplexy is simply a
highly congested condition of the vessels, ^Yhich are prin-
cipally capillary, of the lungs. A congested vessel is of
greater diameter than an uncongested one, and, therefore, is
capable of containing, and really does contain, a far larger
quantity of blood than the vessel in its normal state. There
are many stages or degrees of congestion and of pulmonary
apoplexy : the congestion may be slight, may engage only
one lung or a portion of one ; the dilatation of the vessels
may be but trifling, and therefore the increased quantity of
blood conveyed by them will be but small ; or, on the other
hand, the congestion may be very great, both lungs may be

ORGANS OF RESPIRATION. 385

affected^ and the dilatation of the vessels may be considerable ;
the quantity of blood also contained in such vessels will be
very great. In cases of trivial or partial congestion a slight
retardation in the progress of the blood only occurs ; in the
more severe and complete cases the blood accumulates in the
vessels to such an extent as that the circulation is totally
annihilated, death being the necessary result of such a con-
dition of things.

In what way may the occurrence of this congestion be
explained, and what is the cause of the cessation of the cir-
culation ? The capillary vessels of the lungs are, of course,
incapable of conveying beyond a certain quantity of blood :
any causes, therefore, and there are several, which drive in
upon the lungs a greater amount of the vital fluid than its
vessels are capable of circulating would produce congestion ;
the first effect of which is an accumulation of blood in the
vessels ; the second, an enlargement of those vessels, the coats
of which are highly elastic, as a necessary consequence of the
first ; third, a total cessation of the circulation, arising from
the rapid aggregation of the blood corpuscles in the vessels.
The various degrees of congestion may be followed out with
the microscope in the most satisfactory manner in the tongue
of the frog, or in the web of the feet of that creature. Some
of the vessels will be but slightly dilated ; other capillaries
which, in their normal state are capable of conveying only a
single row of corpuscles, will now be observed to contain two
or three rows ; in others, again, the blood will have ceased to
move altogether.

These several changes in the condition of the blood and

O

its vessels during congestion, are all unaccompanied by
structural alterations, by which character congestion may be
distinguished from inflammation.

Pneumonia. — The phenomena of congestion precede those
of pneumonia, of which indeed it may be considered as the
first, stage ; the second stage of pneumonia consists in the
rupture of some of the capillary vessels, and the escape of a
portion of their contents (whence proceeds the characteristic
rust-coloured expectoration), as well as the effusion without

n II 4

386 THE SOLIDS.

rupture of coagulable lymph through the walls of the vessels,
the consolidation of which in the air cells constitutes the con-
dition of the lung known by the name of hepatization : these
results are probably necessary consequences of the protracted
congestion : the third stage of pneumonia is attended by the
formation and excretion of granular cells in large quantities,
imbedded in a fibrinous fluid: the excreted matter may be
either mucus, constituting the stage of resolution, or it may
be pus, when the pneumonia is said to terminate in puru-
lent infiltration : the difference between the two excre-
tions is one of degree rather than of kind. With respect to
the nature and origin of the granular corpuscles, some phy-
siologists will have it that they are the white corpuscles of
the blood escaped from the vessels — an opinion completely
untenable: they doubtless have an origin external to the
blood vessels, and are to be regarded as of an epithelial cha-
racter, representing as a rule the peculiar epithelium of the
surfaces or parts from which they emanate.

Tubercle. — The earlier microscopic observers approached
the investigation of tubercle, especially of tubercle in the
lungs, with the expectation of finding in tubercular matter
some peculiar element or structure which should account for
the fatality and apparent malignity of that fearful affection,
not knowing fully the true structure of the organs of respira-
tion, and therefore not perceiving clearly that this fatality is
occasioned rather by the peculiar structure of the lungs them-
selves, than by any malignity in the character of the tuber-
culous formation. Some of these observers have even fancied
that they have discovered in the matter of tubercle peculiar
and characteristic cells : it is now scarcely necessary to re-
mark, that careful and extended microscopic investigation
does not warrant any such conclusion.

One of the most accurate views with which I am ac-
quainted respecting the nature of tubercle, is that put forth
by Dr. Addison.*

" Tubercles of the lungs," he writes, " are composed of

* Experimental Researches. Transactions of Provincial Medical, and
Surgical Association, vol. xi. pp. 287, 288.

ORGANS OF RESPIRATION. 387

objects originating from blood corpuscles, which have been
arrested in their circulation through the minute vessels of
the structure of the air cells. So long as this retardation is
confined to the colourless corpuscles, the morbid actions
which ensue are strictly those of an abnormal nutrition, and
various forms of imperfect and degenerated epithelium are
the results ; but if it extend, so as to interfere with the free
circulation of the red corpuscles, we then have all the phe-
nomena of inflammation. No new elementary particles are
formed to constitute a tubercle, and although from the in-
sidious nature of the primary actions, from the delicacy of
the structure, and the important character of the function of
the lungs, the treatment of tubercular diseases must always
be attended with more than common difficulties, still there is
every reason to believe that they are susceptible of preven-
tion and cure, especially if our efforts for the attainment of
these ends be enforced previous to the appearance of a cough,
which is not a concomitant of the first stages of tubercular
deposition in the lungs."

My own views of the nature of tubercle in the lungs differ
in one important respect from those of Dr. Addison ; that is,
with reference to the precise origin of the imperfect and de-
generated epithelial cells. Dr. Addison conceives that they
are derived immediately from the blood itself, while I con-
sider that they proceed from the epithelium, which has been
described as lining the air cells themselves.

A tubercle then I would define as an accumulation of epi-
thelial scales, the imperfect and degenerate representatives of
the true epithelial cells of the organ or part in which the
tubercle is itself developed.

A tubercle of the lungs, at the earliest period of its form-
ation, is exceedingly small, occupying a single cell only;
when this cell becomes filled with tubercular matter, a rup-
ture of its membrane occurs, and thus the extension of the
tubercle takes place from cell to cell; this extension at the
same time being accompanied by a destruction and displace-
ment of numerous of the capillary plexuses.

After the above description, it need scarcely be observed
that tubercles of the lungs are not vascular.

388 THE SOLIDS.

ART. XXI. GLANDS.

MUCH uncertainty has until recently prevailed as to what
really constitutes a gland : some have considered those only
as true glands which are furnished with distinct openings or
excretory ducts ; others again have regarded those organs
only as glands which give forth a secretion : the former view
of a gland would exclude the vascular glands as well as some
others, and the latter, although it would include these, and,
doubtless, also every other glandular structure, is not a suffi-
ciently obvious or structural character, the secreted product
of glands in many cases being furnished in small and scarcely
appreciable quantities, and which again are immediately on
their formation, absorbed, in some cases, into the circulation.
Again, secretions are supplied by parts and extended surfaces
to which, although they are essentially glandular, the term
gland would scarcely be applicable ; of this nature are the
free surfaces of all membranes covered by epithelium, as the
mucous, serous, synovial, &c.

We have still then to inquire, first, what are the essential
structural elements of which all glandular organs or parts are
constituted ? and, second, what is the exact definition to be
given of a gland ?

The researches of modern microscopists have indisputably
proved the fact, that, the only essential elements of a secreting
structure are granular cells and a circulating fluid, the se-
creted product being formed out of the latter by the vital
endowments resident in the former.

According to this definition, the blood itself is to a con-
siderable extent glandular, inasmuch as it contains a vast
number of granular cells to which the elaboration of the
fibrin is, in all probability, due.

Again, the free surfaces of all membranes are glandular;
the epithelium covering them constituting the one essential
glandular element : the varieties in the size and form of the

GLANDS. 38 (J

cells representing this epithelium have been already described
in a former chapter of this work.

Following up this general definition of glandular structure,
a gland may be denned as a collection or aggregation of gra-
nular cells placed in close approximation with a formative
fluid, contained, ordinarily, but not essentially, in the blood
vessels.

This definition of a gland embraces not merely those
glands which are provided with orifices or excretory ducts,
but also those which have no such external or apparent chan-
nels of excretion, as the vascular and other glands.

While it is certain that secretion takes place in the cavities
of the granular cells, as may be actually shown to occur in
the hepatic, renal and sebaceous cells, there is much reason to
believe from the rapid and continual development and dissolu-
tion of successive generations of cells as especially evident in
the case of those of the stomach and small intestines, that this
secretion is liberated in many instances only by the dissolu-
tion of cells themselves. From this view of the relation
existing between the secretion and the cells, it would ap-
pear that the secretive process is accompanied by an en-
dosmotic action.

In the case of fat cells, the secretion is rarely eliminated,
the secretive process is exceedingly slow, and the oleaginous
matter is stored up and retained within the cavities of the
cells themselves, the growth of the cell membrane keeping
pace with the increase in the amount of its fatty contents.

The idea of fluidity is almost inseparably connected with
our notions of a secretion : secretions, however, are not
essentially fluid, for there are solid secretions as well as fluid ;
the sebaceous matter of the glands of the prepuce is a solid,
and the urine of many serpents, as the boa, is also stated to
be solid. There is little doubt, however, but that most and
perhaps all secretions are fluid during the act of their forma-
tion, and that the solidity acquired by certain of them occurs
after their perfection and elimination.

In a strictly systematic arrangement of structures, the
majority of the glands might well be described in connexion

390 THE SOLIDS.

with the internal and external integuments of the body,
the skin, and mucous membrane, since in very many glands,
the secreting structure is contained within, but most probably
not developed from inverted processes of these tissues. Such
an arrangement of the glands, although a very natural one as
far as it goes, would yet not embrace all the glands ; the
vascular and some others would be excluded from it.

The proof of the position that very many glands, and even
the most complex ones, are contained in offsets of the various
modifications of mucous membrane and outer integument,
observers have stated to be derived from an examination of
these organs in an embryonic condition, when even, it has
been affirmed, the most elaborate and varied of them may
be seen as simple follicles or sacks springing from the general
membrane covering the skin or lining the internal cavities.

It would appear, however, from recent and trustworthy
observations, that the principal glandular organs of the body
have each a separate development, and that it is only after
they have been more or less completely formed that they
become attached to the surface of the skin or mucous mem-
brane, upon which their secretions are poured.

Numerous divisions of glands have been proposed by dif-
ferent writers: the majority of these do not require any
special notice : there is one, however, originating with Mr.
Goodsir, which would appear to be ingenious and philo-
sophical, which deserves especial mention. That gentleman
divides glands into two types or classes ; the distinctions
existing between which are founded upon observations de-
rived from the study of the early development of these organs.

In the first type of glandular structure, the follicles which
are at first distinct from the excretory duct, but which sub-
sequently become united with it, are regarded as parent cells,
the granular cells contained within them being secondary
formations, which are continually in process of development,
springing from a germinal spot situated either at the bottom
of the follicle, if this be short, or over its entire surface, if the
follicle be tubular : in this class the follicle is a permanent
structure. •

G LAN PS. 391

In the second type, the follicle is also a parent cell, but is
not a permanent structure, and having attained its maturity,
it bursts, discharges the secondary cells contained within it,
and finally shrivels up, its place being supplied by other
similarly organized cells.

In this type but one gland is included — the testis.

The arrangement of glands proposed below in a tabular form
would appear to be one of the least objectionable as well as
the most practical for purposes of description.

CLASSIFICATION OF GLANDS.

a. UNILOCULAR GLANDS.

Follicles. Soliary Glands.

Stomach Tubes. Aggregated Glands.

b. MULTILOCULAR GLANDS.

Sebaceous Glands. Mucous Glands.

Mcibomian Glands. Labial Glands.

Glands of Hair Follicles. Buccal Glands.

Caruncula Lachrymalis. Gingival Glands.

Glands of Nipple. Lingual Glands.

Glands of Prepuce. Tonsellitic Glands.

Stomach Glands.

Tracheal Glands.

Vaginal Glands.

Uterine Glands.

C. LOBULAR GLANDS.

Salivary Glands. Mammary Glands.

' Pancreas. Liver

Parotid Glands. Prostate Gland.

Submaxillary Glands. Cowper's Glands.
Lachrymal Glands.

392 THE SOLIDS.

d. TUBULAR GLANDS.

Brunner's Glands. Ceruminous Glands.

Sudoriferous Glands. Kidneys.
Axillary Glands. Testes.

€. GANGLIONARY GLANDS.

Compound. Simple.

Brain and Cerebellum. Ganglia of Encephalic Nerves.

Medulla Oblongata and Spinal Ganglia of Sympathetic
Cord. Nerves.

/. ABSORBENT GLANDS.

Lacteal Glands. Lymphatic Glands.

g. VASCULAR GLANDS.

Spleen. Thyroid.

Supra-renal Capsules. Pituitary Body.
Thymus. Pineal Gland.

h. GERMBEARING GLANDS.

Ovaries.

It is doubtful whether the glands admit of any strictly
natural and at the same time convenient classification. The
more simple glands pass by almost insensible gradations into
the more complex, thus leaving but few salient points avail-
able for purposes of division. The separation of the multi-
locular from the lobular glands is to a great extent arbitrary,
and is adopted simply from its convenience. Perhaps the
best division which could be proposed of those glands which
are provided with excretory ducts or openings, is into follicu-
lar and tubular glands.

It is very probable that one of the organs introduced into
the division of lobular glands, viz. the liver, will hereafter
have to be removed from that division and placed by itself
near to the vascular glands, should some recent researches in
reference to the termination of the biliary ducts be confirmed.

GLANDS- 393

It is also probable that further research will disclose the
fact that certain of those glands arranged as mucous glands
do not all possess precisely the same structure.

UNILOCULAR GLANDS.

FOLLICLES.

Crypts and follicles are inverted, and sometimes tubular
prolongations of one variety of mucous membrane termed
compound, and to which that of the alimentary canal, the
gall bladder, the uterus and the Fallopian tubes belong.

In the stomach and in the large intestines these follicles
are so closely set in the membrane, that from the mutual
compression exercised upon each other, they assume a more
or less angular figure ; in the small intestines there are fewer
follicles in consequence of the great number of villi present
in these, and they are not angular, but round. These fol-
licles, which, in the small intestines, are called the follicles
of Lieburkiihn, are met with under two very different con-
ditions; in each of which they present a very distinct ap-
pearance, being in the one case, that is, in their perfect state,
lined by epithelium, and in the other being destitute of this
epithelium. (See Plate Ii.figs. 1. 6.)

The epithelium lining the follicles of the alimentary canal,
is of the same kind as that which covers the interspaces be-
tween the follicles, and is of the conoidal variety. It lines
the entire follicle with a beautifully regular layer of united
epithelial scales, which are so large that they nearly fill up
the cavities of the follicles, a small circular channel only being
visible in each ; this is usually occupied by the mucus
secreted by the cells, and appears at the mouth of each follicle
as a mere depression, surrounded by a circle of radiating
epithelial scales.

To see the epithelium in the follicles of the human stomach,
and even to see the follicles in the mucous membrane of this
organ at all, requires that it should be examined immediately
after death, as the lapse of a few hours is sufficient to allow

394 THE SOLIDS.

of the action of the gastric juice to such an extent as to dis-
solve the follicles entirely.

The follicles dip into the thickness of the mucous mem-
brane to a variable extent in the small and large intestines ;
their extremities reach nearly to the submucous cellular tissue,
and in the lower part of the rectum they are much elongated,
and continued for some distance into the submucous fibrous
tissue between the mucous and muscular coats ; the follicles
usually terminate in rounded and sometimes even in dilated
and bifurcated extremities. (Plate L. fig. 7.)

The object attained by these innumerable follicular inver-
sions of the mucous membrane of the stomach and intestines
is obvious, viz. a greatly extended surface for secretion.

The mucus with which the intestinal canal is so abun-
dantly provided, is chiefly secreted by the epithelium con-
tained in these follicles.

Todd and Bowman thus describe the epithelium of the
stomach cells in the Physiological Anatomy : " They (the
epithelial particles) seem to . lie in a double series, the
deeper being in course of development, while the more su-
perficial is in course of decay. It has appeared to us that
each particle when arrived at maturity has, besides the
nucleus, granular contents enclosed, and that at a subsequent
period the granular contents escape at the free extremity by
a debiscence or opening of the wall, at that part, having the
transparent husk with its nucleus subsisting for some time
longer. The clear structureless mucus which is almost always
found occupying the cells and covering the surface of the
membrane seems to be the altered contents of these particles
after their escape, for the uniform existence of a minute
cavity in the centre of it, when it fills the cells, shows that it
has oozed out from every part of their wall so as gradually
to fill them up."

The ridges or spaces between the follicles of the stomach
and large intestines in the human subject are occupied with
a plexus of vessels larger than capillaries (see Plate \j\..Jig.
1.); these are situated on the deep surface of the basement
membrane, while the epithelial scales are upon its superficial

STOMACH TUBES. 395

surface : in the cat, and many other animals, the interfollicular
spaces, instead of being occupied by a plexus of vessels, con-
tain only a single vessel, which freely inosculates with the
neighbouring vessels, thus mapping out the spaces between
the follicles into somewhat irregular hexagons. (See Plate
LI. fig. 2.)

STOMACH TUBES.

The tubes of the stomach are prolongations of the base-
ment mucous membrane lining the follicles of that organ.
(See Plate L. Jigs. 3, 4, 5.)

These tubes take a parallel course, end in irregularly dilated
extremities, are arranged in sets of three, four, or five tubes,
each of which corresponds with a follicle, and represents the
number of tubes which open into that follicle : it is only,
however, near their entrance into the follicles that they are
thus parcelled out : at their termination they would appear
to be independent of each other, and to be separated by
equal intervals, as represented in Plate L. Jig. 3.

The stomach tubes, unlike the mucous follicles, are filled
with spheroidal or glandular epithelial cells : these cells,
however, do not quite fill up the cavity of the tubes, but
leave in the centre of each a channel or canal, along which
the fluid secreted by the cells flows, until, at last, it reaches
the follicle into which it is poured.

The fluid secreted by these cells is, doubtless, the true
polvent or gastric fluid.

The tubes I find to exist not merely in the stomach, to
which they are generally described as exclusively belonging,
but also in the upper part of the duodenum, which shows
that in the human subject, this portion of the intestine is
to be regarded as a kind of second stomach. I have ob-
served the occurrence of these tubes more than once both in
the duodenum of man, as well as of other mammalia.

The fact of the mucous membrane lining the duodenum
being frequently dissolved some hours after death in the same

I I

396 THE SOLIDS.

manner as that of the stomach would in itself lead to the in-
ference that these tubes were present in the upper part of
that division of the alimentary canal.

Messrs. Todd and Bowman figure the tubes as more or less
branched previous to their entrance into the follicles, an
observation which I can confirm : these gentlemen also thus
describe a modification of the follicles and tubes near to
the pylorus. " Here, in many of the lower animals which
we have examined, for example, in the dog, and it may
with probability be inferred, in man also, a change occurs
in a very gradual manner, but evidently of an important
kind. The membrane is of a paler tint, and its cells
seem not to terminate at once in the true stomach cells
already described, but are prolonged into much wider cy-
lindrical tubes, lined with the same columnar epithelium,
and descending nearly or altogether to the deeper surface of
the compound membrane. For the most part, these pro-
longations of the cells — or, as we shall term them, pyloric
tubes — end, at length, in very short and diminutive true
stomach tubes ; but we have likewise found them terminating
In either flask-shaped or undilated extremities, lined through-
out with the subcolumnar variety of epithelium."

The stomach tubes are each surrounded by a plexus of
vessels.

FALLOPIAN AND UTERINE TUBES.

Tubes somewhat similar to those of the stomach exist, ac-
cording to the observations of Mr. Bowman, in the mucous
membrane of the Fallopian tubes and stomach.

" The lining membrane of the Fallopian tubes, as well as
that of the uterus, is of a compound nature, especially during
gestation, and consists of tubules arranged vertically to the
general surface. It is to be observed that the cilia only
clothe the general surface, and that the epithelium lining the
tubules is spheroidal or intermediate between that and the

GLANDS. 397

prismatic. It is a form of the glandular variety, and bears no

cilia." *

SOLITARY GLANDS.

The solitary glands are scattered irregularly over nearly
the whole surface of the small and large intestines ; they vary
considerably in size, the larger glandulae being found prin-
cipally in the lower portion of the large intestines, and ad-
mitting of easy recognition without the aid of lenses, while
the smaller glands, situated in the lesser bowel, are scarcely
visible, except in states of disease, when their cavities are filled
with secretion. Plate LIT. fig. 6. is a drawing of these
glands as they appeared in a case of muco-enterite in one
of the small intestines, while Plate LI. Jig. 6. is a repre-
sentation of them as found in the larger bowel in a case of
English cholera in a child.

These glands are simple sacks or cells filled with a fibrinous
fluid, containing imbedded in it innumerable spheroidal and
granular cells somewhat smaller than ordinary mucous cor-
puscles.

I have observed these glandule both with and without
central orifices ; these have been more frequently absent than
present ; hence it is very probable that their normal condition
is that of a closed cell, and that when these cavities become
filled with secretion, they rupture, and thus permit their con-
tents to escape, the orifice subsequently closing up again.

Not unfrequently, these glands in certain animals, but not
generally in man, are observed to be surrounded by a circle of
short and tubular cascae ; these by some observers are re-
garded as follicles of Lieburkuhn, and it is uncertain whether
their bases communicate with the cavities of the glands or
not, but it is generally stated not to communicate with the
interior of the glandulse.

The distribution of the vessels around these glands presents
nothing remarkable.

* Cyclopedia of Anatomy and Physiology, Art. " Mucous Membrane,"
vol. iii.

398 THE SOLIDS.

AGGREGATED GLANDS.

The aggregated, agminated or Peyers glands are present in
the lower portion of the ilium only.

They occur in patches of various sizes, each of which
is made up of a considerable number of distinct glandule,
having much the same structure, form and volume, as the
solitary glands, an aggregation of which they may be con-
sidered to be. These patches may be readily recognised
without the assistance of glasses.

In the " glandulae aggregate," central apertures are occa-
sionally present, and they are not unfrequently surrounded
by the short tubular ca3ca3 already spoken of : the interspaces
between the glandulse in the human subject are very generally
covered with villi. The size and limits of these glands may
be best determined by injection.

When examined with glasses as they lie in the mucous
membrane in situ, they appear rounded and flat, presenting
many dark spots, the nature of which is not understood : when
viewed sideways, they are seen to be really of a flask-shape,
the narrow extremity of the flask being turned towards the
surface of the mucous membrane. (Plate LI I. Jigs, 3, 4.)

In inflammation of the mucous membrane of the ilium, a
frequent concomitant of low fevers, these glands are often
found to be entirely eaten away, but sometimes they are
only so far eroded as to present in place of closed glands, a
number of open cells or follicles.

MULTILOCULAR GLANDS.

*

SEBACEOUS GLANDS.

The sabaceous glands are very generally distributed over
the surface of the body, probably not less so than the sudo-
riferous glands, there being but two situations in which they

GLANDS. 399

are stated to be absent, viz., the palms of the hands and
the soles of the feet. On all other surfaces of the body
the two kinds of glands are constantly associated together,
the sudoriferous being much more numerous than the seba-
ceous glands.

They are found especially more or less deeply imbedded in
those portions of integument which are copiously clothed with
hair, as the scalp, whiskers, beard, axilla, pubis, scrotum, and
perineum. They also exist, however, in abundance in certain
situations not usually invested with hair, as in the integument
of the forehead, face, and nose, in the meatus auditorius ex-
ternus of the ear, and for a certain distance up the anterior
openings of the nares : those situated around the nipple of
the female are particularly large, while those of the prepuce
are not merely of considerable size, but yield a solid and
unctuous secretion of a peculiar and penetrating odour.

Those glands which exist in situations which are naturally
clothed with hair always open into the hair follicles, while
those present in parts not furnished with such a covering, yet
nevertheless open into follicles which, although from the ab-
sence of hairs they cannot be called hair follicles, must yet not
be regarded as essentially distinct from hair follicles, since they
in some cases do really contain hairs.

As there are varieties of sebaceous matter, so are there
sebaceous glands which differ structurally from each other ;
thus the cerumen glands of the ear present a conformation
typically distinct from all other sebaceous glands, belonging
to the tubular type of glands, with which they will be de-
scribed.

There are characters, however, in the possession of which
all sebaceous glands agree, save, perhaps, the cerumen glands,
and these are in the semi-solid nature of their secretion and
in the mode of its formation and elimination.

The secretion of the sebaceous glands, like other secretions,
is formed within the cells, which are very large, and in which
it exisis in the form of little spherical and shining particles
of various sizes ; these cells, when filled with the secreted
matter, are thrown off without rupture from the glands in

K K

400 THE SOLIDS.

which they have been formed probably by the development of
fresh cells behind them, so that in general the sebaceous
secretion consists of an aggregation of such eliminated cells.
Some few of the cells, however, do burst and allow of the
escape of their contents.

The sebaceous cells, like other secreting cells in an early
stage of development, are granular and nucleated.

In the character of their secretion, the sebaceous glands
exhibit considerable affinity with the mammary glands. The
milk globules, however, are formed without the cells, and
not within them, as is the case in the sebaceous glands.

The sebaceous glands, exclusive of the ceruminous, manifest
considerable variety in size, form, and arrangement. They
may be thus arranged : first, The Meibomian glands ; second,
The glands of the Hair Follicles, the hairs being in some cases
present in the follicles, and in others absent from them ;
third, The glands of the Nipple ; fourth, The glands of the
Prepuce ; and fifth, The glands of the Carunculae Lachry-
males.

Meibomian Glands.

The Meibomian glands are situated on the inner surface
of the eyelids, between the conjunctiva and the tarsal car-
tilages ; they are of an elongated form, and disposed in a
vertical manner.

The number of these glands in the two eyelids is usually
not less than forty ; in one instance I counted eighteen in the
upper eyelid, and twenty-two in the lower. Their general
form and arrangement differs somewhat in the two eyelids ;
thus, in the lower, they are of nearly equal length, and are
arranged in a parallel manner, while in the upper they are
much longer, almost as long again, their origins describing
an arc ; and in place of being disposed parallelly, they radiate
from each other. These differences depend upon the cor-
responding differences in the size and form of the two eyelids.

Each gland consists of a number of follicles or sacks which
open into a central canal, which pierces the conjunctiva!

GLANDS. 401

membrane at the margin of the tarsal cartilages. The fol-
licles are usually filled with cells, which may be seen through
their walls. These cells present a bright and shining appear-
ance from the oily nature of their contents. (See Plate LIU.

fig. 2.)

Glands of Hair Follicles.

The external surfaces of the body, with few exceptions, the
palms of the hands and soles of the feet being the principal
of them, are covered with the hair follicles, which are placed
at tolerably regular distances from each other, and the aper-
tures of which are visible even without the aid of glasses.

The hairs which issue from these follicles differ in character
according to their situation; those of the scalp being long
and fine ; those of the beard, &c. short and thick ; while those
clothing the general surface of the body are not merely short,
but also exceedingly slender.

In certain situations the hair follicles are frequently with-
out hairs, as on many parts of the face ; this, however, is the
exception rather than the rule, as very fine hairs are gene-
rally present over the entire surface of the face.

It is into these hair follicles that almost all, if not all, seba-
ceous glands open.

The sebaceous glands of the hair follicles consist of several
distinct cells or sacculi, each of which has a separate ex-
cretory duct ; two or more of these ducts, there being some-
times three, four, or five, open into one common duct, which
last opens upon the sides of the hair follicles : there are usually
two, but sometimes more of these common ducts, and very
frequently several of the primary excretory tubes open directly
into the hair follicle. The ducts are large, and usually straight ;
but occasionally, like those of the sudoriferous glands, they arc
slightly spiral. (See Plate LIU. fig. 1. 3.)

Those sacculi which open into the hair follicles by distinct
ducts Are to be regarded as separate glands. In the hair
follicles of the scalp the glands are usually binary.

The glands of the hair follicles arc not confined to the ex-
it K 2

402 THE SOLIDS.

ternal surfaces of the body, but are continued for a certain
distance along several of the outlets. Thus, they occur in
the lower part of the anterior openings of the nares, in the
meatus auditorius externus, in the palpebral conjunctiva, in
the caruncula lachrymalis, in the vulva, and on the interior
surface of the prepuce.

The sebaceous glands vary greatly in size, being, in certain
situations, much larger than in others, as in the eye-lids, ears,
nose, around the nipples, especially of the female, and on the
inner surface of the prepuce.

The cells contained within the ordinary sebaceous glands
differ, in 110 respect, from those of the Meibomian glands
already described. It is in the hair or sebaceous follicles
that the well-known parasite, the Steatozoon Folliculorum,
whose economy has been so well described by Mr. Wilson, is
found, it being placed in these in an inverted position, the
head being turned inwards, as though the animalcule had
crept into the follicles from without. Many of the follicles
frequently contain more than one parasite.

Caruncula Lachrymalis.

The caruncula lachrymalis is usually described as formed
of a single large sebaceous gland : it is not so, however, but
is constituted of a considerable quantity of mixed fibrous
tissue and of blood-vessels, in the midst of which several,
usually four or five, distinct sebaceous glands are imbedded.

These glands, like other sebaceous glands, also open into
follicles, which are certainly hair follicles, although, in the
human subject, they do not usually contain hairs. That they
are really hair follicles, however, is proved by the fact that
in the sheep minute hairs do constantly issue from them.

Glands of Nipple.

The sebaceous glands imbedded in the integument which
forms the areola around the nipple so conspicuous in the
female, differ from other sebaceous glands principally in their
larger size, which allows of their being readily perceived
without the assistance of glasses.

GLANDS* 403

f

Glands of Prepuce.

The glands of the prepuce are also remarkable for their
large size, as well as for the peculiar characters of the secre-
tion which they furnish ; one of these being its semi-solid
consistence ; a second,, its penetrating and remarkable odour.

MUCOUS GLANDS.

The great agents in the secretion of mucus are the cells
contained in the follicles with which all compound mucous
membranes are furnished ; there is, nevertheless, a descrip-
tion of gland very generally distributed, differing anatomi-
cally from the follicles, also called mucous, and which is, in
like manner, supposed to furnish a mucous secretion. It is,
however, very probable that as there are structural differences
between the two, so are there differences in the nature of the
secretion elaborated by them.

Before entering into a description of the mucous glands,
it will not be out of place to present to the reader the
results of some additional researches on the structure of
mucous membranes : at a former page of this work it was
stated that mucous membranes may be divided into simple
and compound according as they contain follicular involutions,
or are destitute of such inverted processes ; and that the com-
pound membranes were that of the alimentary canal from the
cardia downwards, of the gall bladder, and of the uterus
and Fallopian tubes, according to Bowman. Further observ-
ations have, however, shown me that on the one side the
mucous membranes of the mouth (including that which lines
its roof, which invests the tongue, and which covers the tonsils,
uvula, and epiglottis), of the resophagus down to the cardia, of
the vagina and neck of the uterus, of the vesicuke seminales,
as well as the Schneiderian membrane, are also compound ;
while, on the other, the mucous membranes of the Eustachian
tubes, of the trachea, and bronchial tubes, of the bladder,
and of the unimpregnated uterus, and Fallopian tubes, are
simple mucous membranes.

The follicles of the mouth are somewhat large, scattered,

K K 3

404 THE SOLIDS.

and mostly simple ; those of the oesophagus are small, and not
unfrequently divided into branches near their extremities;
the follicles of the vagina resemble somewhat those of the
oesophagus, but are much more branched, very many of the
follicles terminating in several offsets, and becoming in fact
perfect multilocular glands : the follicles of the Schneiderian
membrane are the largest hitherto noticed, and appear to be
simple inversions of the membrane.

It has been stated that the mucous membrane of the uterus
and Fallopian tubes is simple, in which respect there is a
difference between the observations of the author and those
of Mr. Bowman. Considerable pains have, however, been
taken to arrive at the truth ; and it is conceived that the
mucous membrane of the parts cited affords one of the best
examples which could be given of a simple and delicate mucous
membrane. The membrane covering the lips of the uterus
and lining the orifice of that organ is, however, like that of
the vagina follicular, the follicles in the latter situation being
particularly large ; and it is these follicles which yield the
thick and tenacious mucus which usually more or less com-
pletely plugs up the uterine orifice.

Mucous glands occur in very many and different localities,
in several of which they have received distinct names taken
from the parts or situations in which they have been found.
Thus we have labial, buccal, tonsillitis lingual, and tracheal
glands : following up a similar kind of nomenclature for these
glands, we might add to this list Eustachian, palatine, pha-
ryngial, and bronchial glands, also glands of the uvula.

In the roof of the mouth the mucous glands are very
numerous, forming almost one continuous glandular layer,
provided with many orifices disposed at tolerably regular dis-
tances from each other : they are also numerous in the tonsils,
but much less so in the uvula : on the dorsum of the tongue
mucous glands occur but very sparingly, and mostly near the
root of this organ.

There are some few situations in which mucous glands
have been described as present, in which they would appear
to be entirely absent ; as on the margins of the gums, where

GLANDS. 405

they have been called gingival, in the uterus and vagina, where
they have been named uterine and vaginal glands : in the
stomach, also, where they are known as the lenticular glands,
they are very frequently wanting.

There are also certain glands which have not been gene-
rally placed in the category of mucous glands, which, never-
theless, are really structurally identical with them : of this
nature, are Brunner's and Cowper's glands.

From the preceding observation, it follows that Brunner's
and Cowper's glands should be described with the other mu-
cous glands : it will, however, be seen hereafter that the
former present certain resemblances to the tubular and the
latter to the lobular glands.

Messrs. Todd and Bowman * regard the mucous glands as
identical in structure, and probably in function also, with the
salivary glands : that they are not salivary glands, however,
may be shown, first, by the anatomical differences which may
be pointed out as existing between mucous and salivary glands,
as well as, secondly, by the fact that mucous glands occur in
situations — as in the trachea, &c. — where they could serve
no purpose as salivary glands. Mucous glands occur in two
forms : a simple and compound form. In its simple or sim-
plest form, a mucous gland consists of a single duct in com-
munication, at its origin, with a saccated membrane, each
sacculus of which forms an imperfect follicle. In its com-
pound form, it consists of several ducts, each of which, at its
origin, is in like manner in connection with a bunch of in-
complete follicles.

The chief anatomical characters which distinguish mucous
glands from the salivary, to which, indeed, they bear con-
siderable resemblance, depend upon the fact that, in the
mucous glands, the follicles are incomplete ; that is, they
open into each other and into a common central cavity, from
which the single efferent duct proceeds ; while in the salivary
glands each follicle is a distinct body of a rounded or oval
form, and provided with a small primary efferent duel.

* Physiological Anatomy, page 182.
K K 4

406 THE SOLIDS.

Independent of the important differences indicated in the
preceding paragraph, there are others, viz. the larger size of
the follicles of the mucous glands and the coarser and firmer
texture of the membrane which constitutes their parietes.

That the follicles do really communicate with each other
is proved by the numerous circular apertures which they fre-
quently present, and which reminds one of those of the air-
cells of the lungs. (Plate LIILjfy. 4.)

The epithelium contained within the follicles is very small,
the majority of the cells being spherical.

The membrane of the follicles would appear to be fibrous,
and is sufficiently resisting to preserve their form under or-
dinary pressure and manipulation.

These glands have been already referred to under the
head of mucous glands, with which they are structurally
identical.

I was led, for a short time, into the error of arranging them
with the tubular glands, in consequence of observing that each
of the larger glands of Brunner was generally furnished with
several tubular ducts ; and this led me at first to infer that
they were formed entirely upon the tubular type, which is
not the case.

In those instances in which more than one duct proceeds
from what appears to be a single gland, this gland is not
really simple, but compound ; that is to say, it is formed of
several clusters of follicles held together by fibrous tissue,
and from each of which a separate efferent duct proceeds.

The glands of Brunner occur only in the duodenum, and
occupy usually the upper two thirds of that intestine : their
number and extent of distribution vary, however, in dif-
ferent subjects.

For further particulars, see the description of the (( Mucous
Glands."

GLANDS. 407

COWPER'S GLANDS.

Cowper's, or the antiprostatic, glands are, as already men-
tioned, mucous glands, being the largest examples of this
description of gland met with in the human body.

The description given of these glands by authors in general,
their large size and their apparent constitution of lobules,
were the reasons which led to their being temporarily classi-
fied with the lobular glands.

The description given of the mucous glands applies in
every respect to these.

A knowledge of their true structure and relationship ex-
plains their use, concerning which many vague conjectures
have been hazarded.

LOBULAR GLANDS.

SALIVARY GLANDS.

The salivary glands include the parotid, submaxillary, and
lingual glands, together with the pancreas.

These several glands resemble each other very closely in
structure, as well as in the characters of the secretions
furnished by them.

The salivary glands consist of lobes and lobules, on the
surface of which the blood-vessels ramify ; the lobes are made
up of the lobules, and the lobules themselves consist of fol-
licles of a rounded or oval form, and each of which is fur-
nished with a minute efferent duct, which, uniting with the
other ducts of the same size, forms other larger ducts, and
these, uniting again with others of still larger calibre, at
length form, by their union, the main excretory tube of these
organs. (Plate lAV.figs. 1, 2, 3, 4, 5.)

The follicles contain numerous minute granular cells ; and
those of the pancreas, in addition, frequently many shining
globules of an oleaginous character.

408 THE SOLIDS.

Such is a brief description of the salivary glands in their
adult form : in their embryonic condition, however, they do
not consist of lobes and lobules, but the terminal efferent
ducts end in single follicles, which afterwards become mul-
tiplied, until at length clusters of them appear, — the incipient
lobules. (Plate lAV.figs. 1, 2.)

The structure of these glands may be readily followed out
without the aid of injection.*

LACHRYMAL GLANDS.

These glands resemble the salivary in all essential structural
particulars : they are, however, separated from them in con-
sequence of the difference in the character of the secretion
which they furnish.

MAMMARY GLANDS.

The mammary glands do not require any lengthened de-
scription, since they also are formed upon precisely the same
type as the salivary and lachrymal glands.

The principal structural difference has reference to the ef-
ferent ducts. Each salivary gland is furnished with but a
single excretory duct, while to each mammary gland there
are as many as eight or ten ducts which open on the apex of
the nipple : the ducts of the mammary gland are also re-
markable for their great capacity, for it is in them that the
milk principally collects when it is allowed to accumulate.

* It will be observed, that the above description of the salivary
glands agrees closely with that ordinarily given. An examination of these
glands instituted since this description was in type, has convinced me
that they approach in organization very nearly to the mucous glands of
which they are to be considered as a variety. The salivary glands differ
indeed from the mucous in the particulars already mentioned, viz. in the
less size of the follicles, and in their more complete shape, but neverthe-
less are formed upon a similar type of organization. The efferent duct
with which each of the follicles of the salivary glands is said to be fur-
nished is so short, that it in very many instances scarcely deserves the
name of such ; the general arrangement is that of a number of follicles
almost sessile, clustering around the terminations of the salivary ducts.

GLANDS. 409

When the follicles of a mammary gland in an active state
are examined, vast numbers of milk globules of various sizes
will be perceived within them ; and lying in the midst of
these, the small granular secreting cells will be seen : these,
however, do not contain milk-globules, from which it follows
that the milk corpuscles are not formed within the granular
cells, but external to them, although still within the cavity
of the follicles. (Plate lAV.figs. 3, 4, 5.)

Mammary glands exist in the human male as well as
female breast, the essential structure being the same in both,
as proved by the many cases now on record, in which infants
have been suckled by men.

In childhood and old age the mammary glands consist of
white fibrous tissue in the midst of which traces only of the
follicles can be perceived.

Numerous lacteals arise from the neighbourhood of the fol-
licles ; by these, the more watery parts of the milk are absorbed
when this is retained for any length of time within the breast,
and in this way the distension of that organ is from time to
time relieved.

LIVEK.

The liver has been described as consisting, like the other
glands of the lobular form, of lobes, lobules, and follicles or
acini; and indeed in some of the lower animals, this organ has
such a constitution. It has, nevertheless, recently become a
matter of very great doubt whether in the Mammalia, at least,
the same type or organization prevails, and whether the struc-
ture of this gland in this class of animals is not of a totally
different kind.

The mammalian liver consists indeed of lobes and lobules,
but the question is as to the existence of the follicles or acini
furnished with their efferent ducts.

In the adult liver, the division into lobes, even, is essen-
tially arbitrary, so that, in fact, it is of lobules alone that the
liver is entirely composed.

Lobules. — The lobules of the liver are aggregations or

410 THE SOLIDS.

masses of granular or secreting cells, of a more or less angular
form, first resting upon, and then traversed by, branches of
the hepatic vein, and enclosed on all sides by a process of the
capsule of Glisson. The intervals separating the sides of two
lobules from each other are called interlobular fissures, and
those which exist where three or more lobules touch each
other, interlobular spaces.

These lobules, for the most part, are perfectly distinct from
each other ; nevertheless not unfrequently two of them are
more or less united together, as is seen especially on the sur-
face of the liver, and in preparations in which the hepatic
system of vessels has been injected. (Plate LIV. fig. 6.
Plate LY./^. 1.)

The lobules of the liver are of sufficient size to be easily
recognized with the unassisted sight : they vary, however, in
dimensions, not merely in the liver of different animals, but like-
wise in that of the same : in some animals, also, as in the rabbit
and pig, their form, as well as their size, may be clearly defined;
and in these they are evidently angular. (Plate \Jf.fig. 1.)

Such is a brief description of the lobules of the liver : the
supposed follicles or acini are nothing more than the intervals
between the meshes of the capillary vessels which ramify
through the substance of the lobules, and the outlines of which
vessels may be readily followed, even without the aid of injec-
tion, their course being indicated by a number of dark lines.

Mr. Kiernan supposed that the acini were really follicles,
and that they occupied the spaces which he conceived existed
between the meshes of his lobular plexus of biliary ducts.

The secreting apparatus of the liver consists not only of
lobules and their component cells, but also of biliary ducts
and gall bladder.

Biliary Ducts. — In his admirable paper on the liver, in-
serted in the Philosophical Transactions for 1833, Mr. Kier-
nan describes the biliary ducts as terminating in the substance
of the lobules in a complicated network of minute biliary
vessels, which he termed the lobular biliary plexus. Much
doubt, however, has recently been cast upon the accuracy of
this description, notwithstanding that it has received the

GLANDS. 411

confirmatory testimony of very many high microscopical au-
thorities.

The first observer who, I believe, expressed doubts of the
existence of a lobular biliary plexus was Mr. Bowman, to
whose numerous microscopical researches, science is so much
indebted.

More recently still Dr. Hanfield Jones, in a paper " On the
secretory Apparatus of the Liver * " has not merely expressed
the same doubts, but has entered fully into the reasons on
which his opinion is based.

Dr. Jones founds his belief of the non-existence of a lobular
biliary plexus upon the following observations : —

" First, the non-existence of basement membrane in the interior of the
lobules which, in common with Mr. Bowman," he writes, " I have been
unable to detect ; yet were this simplest constituent of a duct present it
could hardly escape notice, especially as in other glands it admits of being
readily demonstrated ; at the broken margin of a lobule it may be well seen
that the broken extremities of the linear series are quite free, and exhibit
no trace of any containing membrane. Secondly, if the margin of a
lobule be carefully examined, where it forms the sides of a fissure, the
basement membrane may often be clearly seen, and through its transpa-
rent texture the terminal cells of the linear series are easily distinguished,
resting against and contained by it. Now were the membrane inflected
to form lobular ducts, surely some indentation or irregularity would be
visible at the margin of the lobule, but I have often traced the outline
carefully without observing any such. A third proof is supplied by the
result of some experiments which I made on rabbits. I tied the duct,
com. choled., and shortly after death, which took place at periods varying
from two to four days, I examined their livers : these organs were
found to be beset on the surface and throughout their substance with
numerous spots of deep yellow colour, evidently produced by accumu-
lation of bile : a section of these spots, examined under the microscope,
showed that they were very partial, never extending throughout the
whole of a lobule, but frequently situated in two or more adjacent ; their
outline was always well defined, and not the slightest appearance of a
distended plexus of ducts could be observed. This last evidence appears
to me conclusive. I can hardly conceive, that if any plexus of anastomosing
ducts existed, the accumulation of bile should take place in definite
spots,, and those not always situated in a single lobule, but in two or
three adjacent."

Philosophical Transactions, 1846.

412 THE SOLIDS.

Of the proofs of the existence of a lobular biliary plexus,
supposed to be derived from injection, it may be remarked,
that these are, in all probability, fallacious, the injection es-
caping from the extremities of the biliary ducts, and passing
into, generally, branches of the portal vein, from which it
extends irregularly into the lobular capillary plexus, and it is
this plexus filled with injection from the biliary duct, that
Mr. Kiernan, it appears to me, took for a lobular biliary plexus.
It still, however, must be regarded as a singular circumstance
that the injection should so generally pass, after its escape
from the ducts, into blood vessels, in place of becoming extra-
vasated around the apertures of the ducts from which the in-
jected material has escaped.

Presuming it, then, to be concluded that there is no lo-
bular biliary plexus, let us next inquire in what manner the
biliary ducts do really terminate.

From the further researches of Dr. Hanfield Jones, con-
tained in a recent paper communicated to the Royal Society,
and entitled " On the Structure and Development of the
Liver," it would appear that the biliary ducts terminate in the
vertebrate series of animals in the interlobular fissures and
spaces in closed and rounded extremities. (Plate LVIL

fig- 1.)

If a branch of the hepatic duct be taken up with the forceps,
it may, by delicate manipulation, be dissected out from the
surrounding parenchymatous tissue. A branch thus prepared,
when placed under the microscope, will be seen to be com-
posed of numerous ramified biliary ducts of various sizes : the
extremities of the majority of these are even broken off; but
several are evidently entire, and these are rounded, as repre-
sented in Plate LVII. fig. 1.

These ducts are not simple tubes, formed of basement meni-
brane, but are lined by a regular layer of epithelial scales :
these serve to secrete the mucus, which partly occupies them ;
and their presence accounts for the great difficulty expe-
rienced in getting the injection to flow along the ducts.

The experiment of dissecting out a branch of the hepatic
duct from the parenchymatous tissue of the liver is most readily

GLANDS. 413

performed in the soft livers of most fish ; as the plaice, sound,
&c. ; but it may be also effected in the livers of the various
mammalian animals.

The author has repeatedly examined branches of the he-
patic duct thus prepared, and his own independent observa-
tions fully corroborate those of Dr. Hanfield Jones, to whom,
for his very carefully conducted inquiries on the intimate
structure of the liver, physiological anatomists are much in-
debted.

The mucous membrane lining the larger hepatic duct is,
according to the observations of Mr. Kiernan, follicular.

Secreting Cells. — The secreting structrue of the liver, as
of all other truly glandular organs, is cellular, the majority of
the cells being perfect, and consequently nucleated, but some
few consisting of nuclei only, the most essential element of
the cell. Each cell may contain more than one nucleus.

These cells are disposed in series, which radiate from the
centre of each lobule, occupied by the lobular hepatic vein :
the radii are not formed of single rows of cells placed
simply end to end, but the cells frequently partially overlap
each other. (Plate LIY./^. 6.)

This linear disposition of the cells would appear to be de-
termined by the radiated arrangement of the vessels which
proceed on all sides from the central hepatic vein.

Dr. Jones considers that this arrangement of the cells is
connected with the secretion of the bile, and that it facilitates
the transmission of this fluid from the centre to the circum-
ference of the lobules : when it has reached this it is discharged
into the interlobular fissures and spaces, to be absorbed into
the ducts by an endosmotic action determined by the denser
mucoid fluid contained within them.

Dr. Hanfield Jones has also observed that frequently the
cells are not merely disposed in linear series, but that they
likewise coalesce with each other by their opposed margins,
whereby the cavities of several cells are made to communicate
with dach other. This union of the cells Dr. Jones considers
to be intended to facilitate still further the transmission of

4:14 THE SOLIDS.

the bile along the series of cells ; and he seeins disposed to
regard it if not absolutely essential to this transmission, yet
as of very general occurrence. There can be no question,
however, but that, in the great majority of cases, the bile is
passed from cell to cell independent of any such union :
this is proved by the exceeding rarity of the occurrence of
rows of cells united in the manner described and figured by
Dr. Jones.

The same accurate observer considers that the first secre-
tion of bile takes place in the most central cells of the lobule,
and that this fluid is accumulated in the greatest quantity,
and its elaboration perfected, in the marginal cells of the lo-
bule. These opinions are founded upon the following ex-
periments and observations: thin sections of the liver of a
rabbit being examined, the ductus communis choledochus of
which had been tied twenty-four hours before death, it was
manifest, in almost every instance, that accumulation of bile
had taken place in the centres of the lobules, as indicated by
a yellow zone of some width surrounding the intralobular
vein. Now this case, in the opinion of Dr. Jones, presents
the earliest effect of interruption to the flow of the secretion ;
and the appearance described seems to point out the exact
spot where the secretion had its origin, viz. in the commence-
ment of the rows of cells surrounding the central axis of the
lobule, as represented by the lobular hepatic vein : again, in
many livers, a remarkable difference may be observed in the
condition of the marginal cells and those placed more cen-
trally ; while the latter have appeared of their usual pale or
light yellow colour, and have contained but one or two minute
oil globules, the former have presented a darker and more
opaque appearance, arising from the presence of numerous oil
globules.

These observations, especially when considered in connec-
tion with the mode of termination of the bile ducts, render it
almost certain that the secreting process reaches its termina-
tion near the margin of the lobule.

Dr. Jones recognises an active and a passive condition of
the lobules of the liver, and thus describes the differences in

GLANDS. 415

the appearances of the margins of the lobules in the two

states : —

" The appearance which the margin of a lobule presents when the pro-
cess of secretion has been proceeding actively, differs much from that
which is observed when the lobule, so to speak, is quiescent: in the
Litter case, as I have described it, the margin is well denned, and bounded
by a distinct basement membrane ; while the terminal cells of the linear
series contain few and minute oil globules, and do not appear to project
outwards in any degree : in the other case the margin of the lobule has
an opake cloudy appearance from the multitude of oil-globules. Several
cells are seen projecting into the cavity of the duct, giving the wall oc-
casionally a tuberculated appearance : these cells contain oil-globules, and
their wall is sometimes so extremely delicate as to be barely perceptible
even under a high power. Very many oil-globules are also seen, which
lie evenly in contact with the sides and floor of the duct : it is difficult to
determine whether these have escaped from their cells or not : it seems
probable, however, that they are for the most part free, having recently
been liberated by the solution of their cell wall. The margin of a lobule,
in the condition now described, presents no trace of basement mem-
brane ; the cells themselves form the wall of the ducts, preserving still the
general outline : it seems, therefore, certain that the basement membrane
is only a temporary structure, which disappears when the cells are actively
discharging their contents. A forcible and instructive contrast to the
above condition was exhibited by a liver which I examined, which was in
an advanced state of fatty degeneration : in this the linear arrangement
of the cells was lost; they lay confusedly together; and were gorged
with their fatty contents ; the margin of the lobule, far from exhibiting
any tendency to discharge the retained secretion, was invested, and, as it
were, closely bound by a membrane, not of the delicate transparent tex-
ture of the basement tissue, but much more opake, and closely resem-
bling the semi-fibrous aspect of thin layers of false membrane."

With respect to the dissolution of the membrane sur-
rounding the lobules at the period of the most active secre-
tion of the bile, it may be remarked that it is a matter of
very great question whether this is either a constant and
necessary occurrence, or even a very frequent one.

Gall Bladder. — The gall bladder is composed of an outer,
strong, fibrous tunic, and an inner mucous one : this latter
has a honeycomb arrangement, and is of the follicular type :
the larger meshes, which are plainly visible to the unaided
sight, are divided by ridges of membrane into four or five
other spaces or depressions of irregular size and form, also

L L

416 THE SOLIDS.

discernible without glasses ; and these again are still further
subdivided into other cells very numerous, and which are
only to be seen with the aid of the microscope. It is these
last which constitute the follicles of the mucous membrane
of the gall-bladder, which differ, however, greatly from the
ordinary tubular follicles of compound mucous membranes,
being simple cells or depressions formed by the plaited and
ridged arrangement of the membrane of the gall-bladder. The
follicles in the hepatic duct, and also in the inner tunic of the
vesiculae seminales, would appear to be of the same character.

If air be inserted, by means of the blow-pipe, beneath the
mucous coat, the latter will be thrown up into lobes, each
of which corresponds with one of the larger honeycomb cells:
this fact shows that the mucous membrane of the gall-
bladder is bound down to the fibrous tissue beneath, prin-
cipally in the intervals between the cellular depressions
alluded to.

Injection thrown into the ductus communis choledochus
very frequently reaches the coats of the gall-bladder : this
fact affords an interesting and striking proof that the vessels
ordinarily injected from the common hepatic duct are not
biliary, for it is generally acknowledged that biliary ducts do
not exist in this situation, — a conclusion to which one, with-
out hesitation, arrives, on reflecting that in such a situation
they could serve no possible purpose.

General Remarks. — Should the foregoing account of the
mode of termination of the biliary ducts be correct, of which
scarcely a reasonable doubt can be entertained, it is evident
that in the vertebrate class of animals, at least, the liver is
not of the follicular type, and that in them this organ should
be separated from those glands formed on the follicular type.
In the fact of the secretion making its way into closed vessels,
the liver clearly manifests an intimate and essential relation-
ship with the vascular glands.

The liver, then, in the vertebrate series, is the only excep-
tion, with which we are at present acquainted, of an organ
which, being furnished with an excretory duct, is yet not
formed on the follicular plan of development.

GLANDS. 417

In all follicular glands, the secreting cells are situated on
the internal surface of the basement membrane : in the liver,
however, they are placed upon its external surface, the true
basement membrane terminating with the termination of the
biliary vessels.

Mr. Bowman regards the innumerable series of secreting
cells as representing the continuation of the biliary ducts,
and a rudimentary condition of which he considers them to
be ; in the same manner as linear series of granular cells re-
present, according to some observers, the rudimentary form of
other vessels and tissues ; as, for example, the muscular fibre
and the primitive nerve tubule.

Vascular Apparatus.

The vascular apparatus of the liver has been well under-
stood since the period of the publication of Mr. Kiernan's
Researches. This apparatus consists of hepatic veins, portal
vein, and hepatic artery.

Hepatic Veins. — The venas cavse hepatica? commence in
the centre of each lobule of the liver by a plexus of capil-
laries, which penetrates it in all directions ; these uniting,
form larger vessels, and which, again, join together, to con-
stitute the central lobular vein : this escaping from the lobule
altogether, becomes what has been termed the sublobular
vein, and it next unites with other sublobular veins to f(5rm
the main branches of the hepatic veins. (Plate LY.^. 1, 2.)

Portal Veins. — The portal vein is mainly formed by the
union of the inferior and superior mesenteric veins; and
these, again, have their origin principally in the confluence of
the capillary vessels of the villi of the small intestines.

The portal vein enters the substance of the liver at the
transverse fissure. After numerous ramifications, many of its
branches are spread over the outer surface of the lobules :
these Jbranches are called the interlobular veins : from these
branches others still smaller proceed ; these, penetrating the
substance of the lobules, break up into capillaries, which unite
with the capillaries of the lobular hepatic veins, already spoken

L L 2

418 THE SOLIDS.

of; and it is the capillaries of both hepatic and portal veins,
thus united, that constitute the lobular capillary plexus,
(Plate LV.^. 4.; Plate Irfl.fig. 1.)

The lobular plexus may be completely injected either from
the portal or hepatic veins, as might be supposed from the
fact of its being constituted of vessels derived from both.
This plexus, however, is not always fully injected : it is
only when the operation of injection has been very success-
fully performed that this result is secured : sometimes, in
injecting from the portal vein, the injection fills only those
vessels which ramify on the surface of the lobules, viz. the in-
terlobular veins, as represented in Plate ILV.Jig. 4. ; in other
instances, the injection will penetrate further, and fill that
portion of the lobular plexus which is formed by the capil-
laries which belong especially to the portal vein ; in this case
a zone of capillaries surrounds each lobule, as figured in
Plate LVI. fig. 1. In others, again, the injection will fill
the entire lobular plexus, and extend even to the central
lobular hepatic vein (Plate LVI. fig. 4) ; in this latter case,
the entire section of the liver appears but a mass of capillaries,
the size and form of the lobules being indicated merely by
the cut extremities of the larger lobular and interlobular
vessels.

On the other hand, in injecting from the hepatic veins, the
injection may reach only the central lobular vein and its
principal ramifications, as shown in Plate LV.^. 1. ; or it
may fill that portion of the lobular plexus especially formed
by the capillaries of the hepatic veins, in which case each
lobule will appear to be the centre of a separate injection
(Plate LV.^. 2.) ; lastly, the entire lobular capillary plexus
is sometimes injected from the hepatic veins in the same
manner as from the portal vein.

In those instances in which two lobules are seen to be
united together, the vessels are also observed to proceed
directly from one to the other ; this communication is es-
pecially evident in injections of the hepatic veins. (Plate L Y.

fig- 2-)

The form of the portal vein, from its origin in the villi of

GLANDS.. 419

the intestines to its termination in the lobules of the liver, may
then be compared either to two trees joined by their trunks,
or to a single uprooted tree. The preceding account renders
it evident that it is from the blood contained in the portal
vein that the secretion of bile takes place.

In those cases in which the blood-vessels become injected
from the biliary ducts, it is usually the portal system which
receives the greater part of the injection ; and this is thrown
into it at different points irregularly, so that there are no
definite zones of capillaries marking out the lobules ; but
masses of capillaries are seen here and there arranged without
any certain order.

Hepatic Artery. — The hepatic artery is the nutritious
vessel of the liver; it supplies the vessels of the hepatic
ducts, the vasa vasorum, and the capsule of the liver.

It is distributed principally, however, to the capsules
covering the lobules, and to the general capsular investment
of the liver.

Some of the interlobular or lesser capsular branches pene-
trate the substance of the lobules, and terminate in the portal
capillaries of the lobular plexus. (See Plate LVI.j^. 2.)

The outer capsular branches are remarkable for their great
length, and the simple manner in which they divide and sub-
divide.

The hepatic artery does not anastomose with the hepatic
vein.

Pathology.

The pathology of the liver may be divided into two sec-
tions, according as the seat of the disease affects its secreting
or vascular apparatus.

Secreting Apparatus.

Two abnormal conditions of the secreting cells of the liver
have Ijeen noticed : in the first, biliary engorgement, the cells
are seen to contain a greater quantity of biliary matter, in
the form of globules of various sizes, than ordinary ; in the
second, fatty degeneration of the liver, the cells are laden

L L 3

420 THE SOLIDS.

with innumerable globules of an oleaginous character ; this
condition of the cells, of course, impairs, to a very great
extent, their secretory powers. (See Plate LVII. Jig. 2,)

Livers thus laden with oleaginous particles have been
termed fatty ; this term, although expressive, is certainly
incorrect. Fat is a distinctly organised cellular constituent
of the higher forms of animal organisation ; and each true
fat globule is a perfect cell, constituted of nucleus and cell
wall. The minute globules of oil existing in the cells of
the liver and of some other glands, especially in disease, have
none of the attributes of cells ; they are merely globular col-
lections of an oily fluid, similar to those which exist in the
cells of cartilages.

It is, therefore, evident that the term fatty applied to
organs affected in the manner described, is scientifically and
fundamentally improper: the appellation of oily would be
more correct.

The truly fatty liver and kidney do, certainly, occasionally
present themselves to our notice ; in these, there is an ac-
cumulation of true fat cells, not, indeed, within the epithelial
particles, but in the interspaces between the lobules and
tubules, and also beneath the capsules to a less degree.

The microscopic characters of the disease called cirrhosis
do not appear to have been as yet satisfactorily determined.

Vascular Apparatus.

A knowledge of the distribution of the blood-vessels in the
lobules of the liver, has enabled the Pathologist to explain
satisfactorily various abnormal appearances connected with its
vascular apparatus.

The lobules of the liver of persons or animals that have
bled to death, or that have died in an exceedingly anaemic
condition resulting from disease, present a pale and exsanguine
appearance, arising from the small quantity of blood contained
within the blood-vessels.

A second very common appearance of the lobules of the
liver, after death, is that in which they arc red in the centre
and pale around the margin. This condition arises from the

GLANDS. 421

presence, in the venous hepatic vessels, of a considerable
quantity of blood, the portal vessels being at the same time
almost destitute of this fluid ; it has been called by Mr.
Kiernan the first stage of hepatic venous congestion, and is
said to be clue to the continuance of capillary action in the
vessels after the general circulation has ceased.

In the second stage of hepatic venous congestion, not
merely the centres of the lobules are red, but also the portal
plexus in parts ; the parts of the lobules which are most free
from congestion are those surrounding the interlobular spaces;
so that the non-congested portions appear in the form of isolated
and irregular patches, in the midst of which are situated the
interlobular fissures and spaces. The second stage of hepatic
venous congestion commonly attends disease of the heart and
other disorders in which there is an impediment to the venous
circulation, and it also gives rise, in combination with accumu-
lation of bile in the secreting cells, to those various appearances
which characterise the nutmeg or dram-drinker's liver.

A third form of venous congestion is that which affects
the portal veins alone ; in this the margins of the lobules are
red, while their centres are pale ; it is the very reverse con-
dition to hepatic venous congestion in its first stage, arid has
been distinguished by Mr. Kiernan, by the name of portal
venous congestion. This form of congestion is rare, and has
hitherto been noticed to occur in children only.

The fluid of the liver, the bile, has already been described
in this work ; in addition to the epithelial scales derived from
the mucous membrane lining the gall-bladder, the bile fre-
quently contains, when inspissated, concrete masses of biliary
matter, which have been mistaken for true cells, also crystals
of cholesterine, gall-stones, and the parasite called the fluke
with its ova.

Hydatids are frequently developed in the substance of the
liver ; these often attain a very large size.*'

* On one occasion I noticed the liver to be thickly studded throughout
with numerous cysts, the largest of about the twelfth or eighth of an
inch in diameter. These cysts contained a gaseous fluid only ; the se-
creting cells included a greater quantity of oil than natural.

L L 4

422 T1IE SOLIDS.

Development of the Liver.

" With respect to the development of the liver, the author * considers
the opinion of Ileichart to be decidedly the correct one, namely, that its
formation commences by a cellular growth from the germinal membrane,
independently of any protrusion of the intestinal canal. On the morn-
ing of the fifth day, the oesophagus and stomach are clearly discernible,
the liver lying between the heart which is in the front, and the stomach
which is behind ; it is manifestly a parenchymal mass, and its border is
quite distinct and separate from the digestive canal at this period ; the
vitelline duct is wide, it does not open into the abdominal cavity, but
its canal is continued into an anterior and posterior division, which are
tubes of homogeneous membrane, filled, like the duct, with opaque oily
contents ; the anterior one runs forwards, and forms behind the liver a
terminal expanded cavity, from which then passes one offset, which
gradually dilating opens into the stomach ; a second, which runs in a
direction upwards and backwards, and forms apparently a csecal prolon-
gation ; and a third and fourth, which are of smaller size, arise from the
anterior part of the cavity and run to the liver, though they cannot be
seen to ramify in its substance ; at a somewhat later period, these offsets
waste away, excepting the one which is continued into the stomach, and
then the mass of the liver is completely free and unconnected with any
part of the intestine. As the vitelline duct contracts, the anterior and
posterior prolongations of it become fairly continuous and form a loop of
intestine, the posterior division being evidently destined to form the
cloaca and lower part of the canal. The final development of the hepatic
duct takes place about the ninth day, by a growth proceeding from the
liver itself, and consisting of exactly similar material; this growth ex-
tends towards the lower part of the loop of the duodenum, which is now
distinct, and appears to blend with the coats of the intestine ; around it, at
its lower part, the structure of the pancreas is seen to be in process of
formation. The further process of development of the hepatic duct will,
the author thinks, require to be carefully examined ; but the details he
has given in this paper have satisfied him of the correctness of the
statement that the structure of the liver is essentially parenchymal."

PROSTATE GLAND.

This gland belongs to the compound follicular division, and
not to the lobular class of glands ; its structure consisting of
clusters of follicles, united by ducts : these follicles are usually
of an oval form, of large size, and frequently communicate
with each other.

* Dr. Hanfield Jones, Abstract of Paper in Philosophical Magazine,
September, 1847.

GLANDS. 423

The follicles cannot be exhibited separately as such, being
mere excavations or cells which exist in the substance of the
gland, and which are lined by prolongations of the mucous
membrane of the urethra.

That the follicles constituting the essential structure of the
prostate gland are simply inversions of the genito-urinary
membrane, is proved by the fact that the epithelium which
lines them is of the clavate form, which has been elsewhere
described as appertaining to the bladder.

In consequence of the large size of the follicles, and of the
fact of the epithelium which lines them forming on their in-
terior but a single arid even layer of cells, a considerable
space or cavity exists in the centre of each follicle.

The tissue out of which the follicles are formed, and to the
presence of which the prostate owes much of its size and
nearly all its firmness, is a good example of the nucleated
variety of fibro-elastic tissue, approaching in its characters
very closely to the muscular fibre of organic life.

The increase which so generally takes place in the size of
the prostate in old age is due to an increased development of
the above-named tissue.

From the preceding description, it would appear that the
office of the prostate is simply to secrete mucus, and that it
does not, as has been conjectured, furnish any peculiar secre-
tion necessary, as some even have supposed, to fecundity.

The most curious circumstance about the prostate is the
almost constant occurrence, in considerable numbers, of con-
cretions or calculi formed of concentric lamella?. These calculi
are situated in the follicles already described; they differ
from each other very greatly in size, form, and colour, and in
the number, arrangement, and strength of the concentric
capsules. Ordinarily, the concentric lamella) are disposed
around a single nucleus of granular and amorphous matter ;
sometimes, however, there are two or even three separate
nuclei within each calculus ; in these cases, each nucleus
will be encircled by its own lamella, the entire of them
being also included in a greater or less number of larger
lamella}. The form of the calculi, although various, has a

424 THE SOLIDS.

tendency to the triangular ; and the colour, although dif-
fering in different glands, depends upon their size and age,
the younger and smaller being transparent and almost free
from colour, the older and larger being of a deep orange or
ochre tint. (Plate LVII. jftyb &.)

The prostatic calculi have been noticed by several ob-
servers ; by Cruveilhier, Dr. Jones, Mr. Quekett, Mr. Adams,
of the London Hospital, Dr. Letheby, and myself.

Dr. Jones* describes them as originating in oval or rounded
nucleated and organic vesicles, which enlarge and then have
their amorphous contents arranged into concentric Iamina3.
Dr. Letheby believes that " they are concretions which arise
exactly like those of the kidney and bladder, viz., by a suc-
cession of external deposits ; " this view is most probably the
correct one.

Dr. Letheby has favoured me with the following observa-
tions on the chemistry of these bodies : " You will find," he
says |3 " that they consist of phosphate of lime, which is
mixed up with a large quantity of nucleated fat cells and
inspissated mucus ; the whole being generally tinted with
some shade of yellow or red."

" They are slowly soluble in strong acetic and muriatic
acids; more quickly when heated, and they then leave nu-
merous fat globules and remnants of cells. They are not dis-
solved by potash or strong ammonia. Heated before the
blow-pipe, they char and leave a small residue of earthy
matter."

The smaller calculi resemble closely the concentric corpus-
cles or bodies described by Mr. Gulliver as occurring in fibrin-
ous clots, and many of them do not present concentric lamella.

TUBULAK GLANDS.

SUDORIFEROUS GLANDS.

The sudoriferous are the most numerous class of glands
in the body, their apertures thickly studding the entire ex-

* Medical Gazette, 1847. f In litt.

GLANDS. 425

ternal surface, and far outnumbering the sebaceous glands,
which have a somewhat similar distribution.

They consist of convoluted tubes of nearly equal diameter,
which unite, at irregular intervals, with each other, forming
looped meshes, all of which terminate in a single excretory
duct. (See Plate LVIL/*/. 4.)

The excretory duct is either straight or coiled spirally, and
it always terminates in a raised and rounded mammillary pro-
cess, evident on the surface of the epidermis. (See Plate
XXIII. fig. 1.) It is straight where the epidermis which it
has to pass through is thin, and where, in consequence, its
course to the surface is short ; on the other hand, it is coiled
in spires which are remarkable for their extreme regularity,
where this membrane is thick, as in the palms of the hands
and soles of the feet (see Plate XXIV. fig. 3.), and where
as a result its course is prolonged. The acting cause which
determines this spiral arrangement is probably the gradual
flattening to which the outer and older layers of epidermic
cells are continually subject from pressure.

The duct of the sudoriferous glands is formed by an inver-
sion of the epidermis itself, similar to that which forms the
lining of the hair follicles. The sudoriferous glands never
open into the hair follicles, but in the intervals between them
and also between the sensory papillae with which the true skin
is covered.

The palms of the hands and soles of the feet, being entirely
free from the sebaceous glands, are occupied exclusively with
the sudoriferous ; they are placed in lines or rows, which are
variously curved, and which correspond with the arrangement
of the sensory papillae of the true skin. The apertures of the
sudoriferous glands on the ridges of the skin are just perceptible
with the naked eye, but they become very evident and con-
spicuous with a lens of moderate power. (Plate XXI V.,/%. 1 . )

The secreting cells of the sudoriferous gliUids are small.

The tubes are formed like those of the testes of a nucleated
variety of fibro-elastic tissue, and are surrounded by a similar
plexus of capillaries. These vessels, as well as the tubes
themselves, are held in position by bands of fibrous tissue.

426 THE SOLIDS.

The following calculations by Mr. Wilson will serve to
convey some idea of the extent and importance of the sudori-
ferous system : —

" To arrive at something like an estimate of the value of the perspira-
tory system in relation to the rest of the organism, I counted the per-
spiratory pores on the palm of the hand, and found 3528 in a square
inch. Now, each of these pores being the aperture of a little tube of
about a quarter of an inch long, it follows, that, in a square inch
of skin on the palm of the hand, there exists a length of tube equal
to 882 inches, or 73£ feet. On the pulps of the fingers, where the
ridges of the sensitive layer of the true skin are somewhat finer than
in the palm of the hand, the number of pores on a square inch a
little exceed that of the palm ; and on the heel, where the ridges are
coarser, the number of pores on the square inch is 2268, and the length
of the tube, 567 inches, or 47 feet. To obtain an estimate of the length
of tube of the perspiratory system of the whole surface of the body, I
think that 2800 might be taken as a fair average of the number of pores
in the square inch; and 700, consequently, of the number of inches in
length. Now, the number of square inches of surface in a man of ordi-
nary height and bulk is 2500 ; the number of pores, therefore, 7,000,000 ;
and the number of inches of perspiratory tube, 1,750,000, that is 145,833
feet, or 48,600 yards, or nearly twenty-eight miles." *

AXILLARY GLANDS.

These glands, first described by Professor Horner and M.
Robin, are probably but a variety of the ordinary sudoriferous
glands.

They are situated in the axillae, are similar in organisation
to the sudoriferous glands, but are much larger than these.

They doubtless furnish the peculiar and odorous secretion,
which characterises the region of the axillse.

This odorous principle, it is said, exists in the blood
ready formed, and the glandular merely separate it from that
fluid. It is also stated that its presence may be detected,
in dried blood, on the addition of sulphuric acid, and that
its odour is different in the male and female, also that even
the blood of different animals may be distinguished by means
of it ; assertions which are very doubtful, f

* Diseases of the Skin, p. 18.

| Annales d'llygiene, vol. i. ii. x. &c.

GLANDS. 427

CERUMINOUS GLANDS.

The ceruminous glands are situated beneath the integu-
ment of the deeper part of the external meatus of the ear.
They occur mixed up with numerous sebaceous glands, but
have no direct communication with these, as they open on the
surface by distinct apertures.

They resemble very closely in structure the sudoriferous
glands just described, consisting, like them, of convoluted
and looped tubes, which unite together and end in a single
slender duct. They differ, however, from the sudoriferous
glands in the fragile character of the tubes, which renders it
somewhat difficult to procure a perfect preparation of one of
them ; this difference seems to arise principally from the ab-
sence, in a great measure, of fibrous tissue, whereby, in the
sudoriferous glands, the tubes are bound together, as well as
of also enveloping plexuses of blood-vessels. ( See Plate L VII.

fig- 5.)

In the external ear of the sheep, in which these glands
may be studied to great advantage, the tubes appear of a pale
straw colour, transparent and glossy, with but few apparent
granular cells, and these totally different from the character-
istic cells of the sebaceous glands, filled with innumerable
globules of oil. The granular cells filling the tubes, and
which are usually concealed by a quantity of oily fluid, may
be made apparent by the addition of acetic acid. The mem-
brane of the tubes is composed of a nucleated form of elastic
tissue. *

From the fact of the ceruminous glands coexisting with
numerous sebaceous glands, it seems probable that the ceru-
men is the mixed production of the two descriptions of glands.

KIDNEYS.

The substance of the kidney, like that of the other large
glands, may be divided, for the purposes of description, into
two orders or systems of structure or apparatus : the glan-

* It seems doubtful, after all, whether the ceruminous are any thing
more than a variety of the sudoriferous glands.

428 THE SOLIDS.

dular or secretory, which is the most important and charac-
teristic ; and the vascular, which is but subordinate.

Secreting Apparatus.

The secreting apparatus of the kidney consists of the tubes ;
their enlarged and globular extremities, which, in part, con-
stitute those peculiar and interesting structures, the Mal-
pighian bodies, and their contained granular cells. (See Plate
LVIII. Jigs. 1. 6., Plate LX. figs. 2, 3.)

Tubes. — The substance of the kidney is divided into an
outer cortical and an inner or medullary part. The former
is generally conceived to be the secreting portion of the
kidney, and the latter merely the tubular or conducting por-
tion through which the urine passes in its way to the ureter.
This notion of the nature of the two parts and of their mutual
relation is certainly erroneous, as is proved by the facts that
both portions of the kidney are alike formed of tubes, and
that all these tubes are abundantly furnished with secreting
cells.

The secreting structure of the cortical part of the kidney
is distinguished by the large size of its tubes ; their tortuous
course ; the loops formed by them, not merely on the surface
of the kidney, but also in its interior ; by the globular en-
largements in which they terminate ; and by the larger size
£c. of their contained cells.

The medullary part of the kidney is characterised by the
smaller calibre of its tubes, their straight course, the absence
of dilated extremities, and the frequency of the union of the
tubes with each other.

The tubes then of the kidney, describing their course from
without inwards, commence in dilated extremities (see Plate
LX. Jigs. 2, 3.), which form part of the structure of the
Malpighian bodies ; they afterwards take a tortuous course,
describing loops on the surface of the organ, as Avell as in its
interior (see Plate LIX. fig. 2. and Plate LYIII. fig. 1.),
until they reach the medullary part, when their course be-
comes straight, and where they frequently unite, especially
near its lower portion, in a dichotomous manner, thus forming

GLANDS. 429

a number of larger tubes, which terminate in the mammillary
processes which dip into the midst of the chambers called
chalices.

According to the above description of the course and origin
of the tubes of the kidney, which is now the generally re-
ceived one, each tube commences in a single dilated extremity ;
it seems to me, however, to be probable that many of the
tubes have their origin in loops ; the fact of the occurrence of
loops throughout both the medullary and the cortical parts of
the kidney, the universal formation of loops on the surface of
that organ, and the non-existence of dilated extremities of
tubes on that surface, all tend to prove the correctness of the
view just mentioned.

The tubes of the kidney, wherever encountered, consist of
a strong and structureless basement membrane (see Plate
LVIII. Jig. 1.); it is worthy, however, of especial notice
that these tubes, as well as their globular terminations, are all
inclosed in a framework constituted of a nucleated form of
elastic tissue. This framework is seen to most advantage in
cross-sections ; this it is which keeps the tubes distinct from
each other, and which explains the occurrence of intervals
between the tubes, seen especially in longitudinal sections.
(See Plate LVIII. fig. 2.)

Malpighian Dilatations. — It is certain that some, if not
all, of the tubes terminate in enlarged extremities. These
dilatations constitute the Malpighian bodies in part only ;
they are of a globular form, and their diameter exceeds
five or six times that of the tube itself. (See Plate LX.
ficjs. 2, 3.) They vary, however, considerably in size, in all
parts of the cortical substance of the kidney ; and Mr. Bow-
man states that they are largest near to the point of junction
between the cortical and medullary portions.

The best way to obtain a satisfactory view of these bodies
is to tear up with needles a fragment of the cortical sub-
stance of the kidney, and to search amongst the divided
shreds for the Malpighian dilatations which are there met
with in all possible conditions. Some will be seen entirely
detached, lying loose in the water in which the fragment has

430 THE SOLIDS.

been torn up, others will be observed to be attached to the
tubes which take their origin from them. All of these, how-
ever, whether attached or loose, will occur in one of two
states ; either the surface of each will be seen to be constituted
of convoluted and branched tubes, the vessels of the Malpig-
hian plexus ; or it will appear perfectly smooth and even.
The former condition is the more frequent ; the latter is by
far the less common, and is explained by the fact that in this
case the Malpighian dilatation is inclosed in a capsule of
fibro-elastic tissue of considerable thickness, a continuation of
that which invests the tubes themselves. (See Plate LX.
figs. 2, 3, and Plate LVIII. fig. 2.)

The Malpighian dilatations rarely, if ever, extend to the
surface of the kidney ; they have been, in all the instances in
which they have been noticed by the Author, covered by con-
volutions of the tubes.

Epithelium. — The epithelium of the kidney presents several
well-marked modifications, in different localities of that organ.
The epithelium of the tubes of the cortical part of the
kidney, save within a short distance of their junction with the
Malpighian dilatations, is composed of large and angular scales
or cells, which are coarsely granular, and which form a regular
layer of pavement epithelium lining the tubes ; the centres of
these are unoccupied with cells, and are thus left pervious for
the passage of the urine. (See Plate LVIII. fig. 6.)

The cells forming the epithelium of the tubes of the me-
dullary part of the kidney are of much smaller size than those
contained in the tubes of its cortical substance, consisting of
nuclei, surrounded by a very narrow border. (See Plate
LVIII. fig. 6.)

The cells situated at the neck of the Malpighian dilatations
are of the ciliated kind : these were first noticed by Mr. Bow-
man in the kidney of the frog, and that gentleman conjectured
their existence in the higher animals ; the Author has seen
them in action in the sheep, rabbit, and horse. (See Plate
LX. fig. 3.)

Lastly, the cells which invariably line the Malpighian
dilatations of the tubes are small and furnished with oval

GLANDS. 431

nuclei. (See Plate LX. fig. 3.) Mr. Bowman considered
that epithelium was not constantly present in these bodies ;
and that, when it was so, it only lined that portion of them in
connection with the tubes. This statement arose in a mis-
apprehension of the real structure of the Malpighian body.

Vascular Apparatus.

The vessels of the kidney consist of the renal artery and
vein, also of a vein which may be called portal : we will first
trace the course of the artery.

Renal Artery. — The renal artery, after its entrance into the
substance of the kidney, divides into numerous branches,
some of them pass between the medullary cones, others tra-
verse these in sets : arrived at the cortical part of the kidney,
many undergo a further subdivision, and some, passing to-
wards the Malpighian dilatations, form in part, upon its ex-
ternal surface, the Malpighian tuft or plexus of vessels (see
Plate LIX.J&7S. 1. 5.) ; others continue onwards to the surface
of the kidney, and there terminate in capillaries. (See Plate
LIX. fig. 2.) Such is a brief sketch of the course of the
renal artery.

The branches of the renal artery take, through the cortical
part of the kidney, a straight and parallel course ; some of
these branches give off lesser vessels on each side, which pass
towards, and are expended upon the Malpighian dilatations,
as also is, ultimately, the terminations of the main vessels from
which the lesser ones proceeded. Others, again, of the larger
and parallel branches, in like manner give off Malpighian
twigs ; but their terminations, in place of being exhausted
upon the Malpighian dilatations, reach the surface, and there
form, with the branches of the renal vein, an interlobular
plexus. It is seldom that a branch of the artery reaches
the surface of the kidney, without first communicating with
the Malpighian dilatations.

Renal Vein. — The renal vein has two origins : one in the
capillaries on the surface of the kidney; these capillaries,
uniting with those of the renal artery, form the plexus, which

M M

432 THE SOLIDS.

ramifies in the interstices left between the terminal loops of
the tubes (see Plate LIX. Jig. 2.) : the second origin is in
the plexus of capillaries surrounding the tubes formed by
the junction of the capillaries of both artery and vein ; from
these two origins and plexuses branches proceed; these,
uniting with each other, form larger vessels, which also pass
through the medullary part of the kidney in sets. (See Plate
LVIII.j^*. 4, 5.)

Portal Vein.' — Each Malpighian tuft or plexus of vessels
is formed, like other plexuses, of capillaries derived in part
from an artery and in part from a vein. As a single arterial
twig proceeds to each Malpighian dilatation — the afferent
vessel, so a single venous twig departs from it — the efferent
vessel ; this vessel is usually of much smaller size than the
artery, and terminates in the capillaries which encircle the
uriniferous tubes. (See Plate LX. fig. 2.)

The efferent vessel of the Malpighian tuft resembles in its
origin and distribution the portal vessel of the liver, being
in connection with capillaries, at both its origin and its
termination : in consequence of this resemblance it has been
termed by Mr. Bowman the portal tein of the kidney ; and
as each Malpighian plexus has a separate efferent vessel,
to the aggregate of these that gentleman applies the term
te portal system " of the kidney.

The above description of the vascular distribution belong-
ing to the kidney differs, in some important respects, from
that given by Mr. Bowman, as we shall now proceed to
make apparent.

In the first place, Mr. Bowman describes the afferent vessel
of the Malpighian tuft as piercing the membrane of the en-
larged extremity of the tube, and as forming within this,
by its numerous subdivisions, the Malpighian plexus : the
efferent vessel, in like manner, perforating the membrane of
the dilatation, or proper capsule.

This view of the position of the Malpighian plexus is un-
doubtedly incorrect; this plexus, like every other plexus
belonging to glands formed on the tubular or follicular types,
is situated on the external surface of the basement membrane,
that is, embracing the globular head of the tubes, and lying

GLANDS. 433

between this and the framework of elastic tissue already de-
scribed. Analogy, therefore, is entirely opposed to the de-
scription of the author of the paper in the Philosophical
Transactions to which reference has been made more than
once.

In the second place, Mr. Bowman describes the renal artery
as being spent upon the Malpighian bodies, with the excep-
tion of a few branches given off to the coats of the excretory
ducts and of the larger vessels; while, according to the
Author's observations, only a proportion of the branches of
the renal artery are thus disposed of.

The accuracy of the foregoing account of the distribution
of the blood-vessels of the kidney is borne out, to a very great
extent, by the results furnished by injection.

1st. The Malpighian plexus can be injected with great
facility by the artery, but not by the vein : the reason of this
will be obvious on a little reflection ; the branches of the
renal artery pass directly to the Malpighian plexus ; those of
the renal vein, commencing from the larger or terminal trunks,
end either in the plexus surrounding the tubes of the kidney,
or in that which lies on its surface between the convolutions
of those tubes ; and it is in one or other plexus that the
efferent or portal vein of the Malpighian tuft terminates ; so
that between the terminal branches of the renal vein and the
origin of the efferent vessel, a complicated plexus is inter-
posed— that surrounding the uriniferous tubes ; the injection,
therefore, before reaching the Malpighian tuft, would have to
traverse the plexus already spoken of; and it is this which
accounts for its being so difficult, if not impossible, to inject
the Malpighian plexus from the renal vein.

2nd. The plexus surrounding the tubes may be injected
with care, from both the artery and vein ; but especially from
the latter.

3rd. The plexus, ramifying between the loops of the tubes
on the surface of the kidney, may also be readily injected
from either artery or vein.

Occasionally, the injection will pass from the blood-vessels,
and escape into the tubes, or their Malpighian extremities.

M !M 2

434 THE SOLIDS.

The tubes themselves, and very rarely their globular ter-
minations, may be injected from the ureter : this is accom-
plished more readily in the kidneys of some animals, as the
horse, than in those of man.

A complete Malpighian body, then, consists of the globular
enlargement of the tube, over which is spread the Malpighian
plexus, formed by branches of the renal artery and portal vein ;
this plexus does not consist entirely of capillary meshes, but
of vessels of different diameters ; the artery divides and sub-
divides : its terminal branches are, however, capillary in size,
but, in place of forming distinct meshes, follow a serpentine
and convoluted course. (See Plate LX. fig. 2.)

Mr. Bowman conceived, as already noticed, that the Mal-
pighian plexus was situated within the globular enlargement
of the uriniferous tube ; and, reflecting on the remarkable
structure of the Malpighian bodies, and on their singular con-
nection with the tubes, was led to consider that the tubes
and their plexus of capillaries are the parts concerned in the
secretion of that portion of the urine to which its character-
istic properties are due (the urea, lithic acid, &c.), while the
Malpighian bodies are an apparatus destined to separate from
the blood the watery portion of the urine.

" It would indeed be difficult," Mr. Bowman writes, " to conceive a
disposition of parts more calculated to favour the escape of water from the
blood than that of the Malpighian body. A large arterj breaks up, in a
very direct manner, into a number of minute branches, each of which
suddenly opens into an assemblage of vessels of far greater aggregate
capacity than itself, and from which there is but one narrow exit. Hence
must arise a very abrupt retardation of the velocity of the current of
blood. The vessels in which this delay occurs are uncovered by any
structure. They lie bare in a cell from which there is but one outlet,
the orifice of the tube. This orifice is encircled by cilia, in active
motion, directing a current towards the tube. These exquisite organs
must not only serve to carry forward the fluid already in the cell, and
in which the vascular tuft is bathed, but must tend to remove pressure
from the free surface of the vessels, and so to encourage the escape of
their more fluid contents. Why is so wonderful an apparatus placed at
the extremity of each uriniferous tube, if not to furnish water, to aid in
the separation and solution of the urinous products from the epithelium
of the tube?" P. 75.

GLANDS. 435

My view of the nature of the Malpighian body differs, in
some respects, from that entertained by Mr. Bowman. The
proper Malpighian capsule is invariably lined by innumerable
granular cells ; for this single and simple reason, therefore, I
regard this body as a secreting organ as much as the urini-
ferous tubes themselves, which present an organisation essen-
tially the same. I differ, therefore, from Mr. Bowman, who
considers the epithelium of the tubes as the sole true secreting
agents of the urine. I conceive that this fluid is formed in
every part of the tubular and- Malpighian surface of the
kidney, and I dissent from the opinion that the Malpighian
body is an apparatus destined for the simple separation of the.
watery parts of the urine apart from any act of secretion.

Nevertheless, I so far agree with Mr. Bowman in his
theory, as to consider that the greater portion of the more
watery parts of the urine proceed from the Malpighian bodies ;
not, however, by an act of simple separation, but by one of se-
cretion. The peculiar arrangement of the blood-vessels, and
the presence of ciliated epithelium at the entrance to the
tubes, are facts in themselves sufficiently conclusive of the
accuracy of this view : as, on the other hand, I conceive the
great extent of secreting surface presented by the tubes to
be in itself sufficient to prove that at least a portion of the
aqueous constituent of the urine emanates from this surface.

An accurate knowledge of the pathology of the kidney
and urine would, doubtless, furnish arguments conclusive as
to the relative functions and importance of the tubes, and
their enveloping plexus and the Malpighian bodies.

The reader will at once observe that one of the arguments
in favour of Mr. Bowman's theory, urged in the preceding
exposition, does not hold good, in consequence of its want of
accordance with the true structure. I allude to the supposed
entrance of the plexus into the cavity of the proper Malpighian
capsule.

In birds and reptiles, the Malpighian plexus is not formed
of a number of convoluted vessels, resulting from the repeated
subdivision of the afferent artery, as is the case in all the
Mammalia, but simply consists of a single coiled vessel, so

436 THE SOLIDS.

that the afferent and the efferent vessels of each tuft are one
and the same by direct continuity. In these classes, the ef-
ferent vessel readily admits of being injected from the artery,
and this in consequence of the simplicity of the plexus sur-
rounding the Malpighian enlargement.

The size of the Malpighian bodies varies, not merely in the
same kidney, but also to a still greater extent in the kidneys
of different animals: they are largest in the elephant and
horse, and smallest in birds.

Development of the Kidney.

According to Dr. Carpenter, " The first appearance of any thing re-
sembling a urinary apparatus in the chick, is seen in the second half of
the third day. The form at the time presented by it is that of a long
canal, extending on each side of the spinal column, from the region of the
heart towards the allantois ; and the sides of these present elevations and
depressions, indicative of the commencing development of coeca.

" On the fourth day, the Corpora Wolffiana, as they are termed, are dis-
tinctly recognised, as composed of a series of caeca! appendages, which are
attached along the whole course of the first-mentioned canal, opening
into its outer side. On the fifth day, these appendages are convoluted ;
and the body which they form acquires increased breadth and thickness.
They evidently then possess a secreting function ; and the fluid which
they separate is poured by the long straight canal into the cloaca.
Between their component shut sacs numbers of small points appear,
which consist of little clusters of convoluted vessels exactly analogous to
the Corpora Malpighiana of the kidney. The Corpora Wolffiana, how-
ever, have only a temporary existence in the higher Vertebrata, although
it seems that in fishes they constitute the permanent kidney. The
development of the true kidneys commences in the chick about the
fifth day. They are seen, on the sixth, as lobulated greyish masses, which
sprout from the outer edges of the Wolffian bodies ; and they gradually
increase, the temporary organs diminishing in the same proportion. The
sexual organs, as will be hereafter explained, also originate in the
Wolffian bodies ; and at the end of foetal life, the only vestige of the
latter is to be found as a shrunk rudiment situated near the testes of the
male. The progress of development in the human embryo seems closely
conformable to the foregoing account. The Wolffian bodies begin to
appear towards the end of the first month ; and it is in the course of the
seventh week that the true kidneys first present themselves. From the
beginning of the third month, the diminution in the size of the Wolffian
bodies goes on pari passu with the increase of the kidneys ; and at the

GLANDS. 437

time of birth, scarcely any traces of them can be found. At the end of
the third month, the kidneys consist of seven or eight lobules, the future
pyramids ; their secreting ducts still terminate in the same canal, which
receives those of the Wolffian bodies and of the sexual organs. And
this opens with the rectum into a sort of cloaca, or sinus urogenitalis,
analogous to that which is permanent in the oviparous Vertebrata.
The kidneys are at this time covered by the supra-renal capsules,
which are very large ; about the sixth month, however, these have de-
creased, whilst the kidneys have increased, so that their proportional
weight is as 1 to 4|. At birth, the weight of the kidney is about three
times that of the supra-renal capsules, and they bear to the whole
body the proportion of 1 to 80 ; in the adult, however, they are no
more than 1 to 240. The Corpora Wolffiana are, when at their greatest
development, the most vascular parts of the body next to the liver ;
four or five branches from the aorta are distributed to each, and two
veins are returned from each to the vena cava. The upper veins and
their corresponding arteries are converted into the renal and emulgent
vessels ; and the lower, into the spermatic vessels. The lobulated appear-
ance of the kidney gradually disappears ; partly in consequence of the
condensation of the areolar tissue, which connects the different parts ;
and partly through the development of additional tubuli in the inter-
stices."

It is only necessary to observe, in addition to the descrip-
tion of Dr. Carpenter, that, although the development of the
kidney commences near to the Wolffian body, it is yet not
formed out of it, but has an independent origin in its own
proper blastema or primordial matter. In its earliest condi-
tion in the Mammalia, it consists of tubes proceeding from
the hilus outwards towards the circumference in bundles ;
these tubes afterwards separate and become contorted, yet
all terminate in enlarged and vesicular extremities, — the
Malpighian bodies. In the earliest state in which the kidney
can be examined, the caeca alone exist in connection with
short tubes ; the central or proximal extremities are free,
and not yet united to the ureter. This fact proves that the
kidney is not an involution of the genito-urinary mucous
membrane, but an independent formation, as is, probably,
every other gland.

Such is a simple, concise, and, it is believed, in all essen-
tial particulars, a correct account of the normal tmatomy of
the kidney.

438 THE SOLIDS.

Reference to the various discrepant, contradictory, and
often erroneous statements of many writers on this subject has
been hitherto purposely avoided, lest such should obscure the
simplicity of the description just given. A few of the more
remarkable statements and opinions advanced respecting the
anatomy of the renal organs may now, however, be noticed
with advantage and interest.

Every statement, without exception, made by Mr. Bowman,
one of the earliest and very best writers on the minute
anatomy of the kidney has been from time to time contra-
dicted by different observers ; by others, again, the descrip-
tions of that gentleman have been confirmed, and not
denied. As might be readily imagined, the truth lies not
exclusively with either the denying or the confirming ob-
servers.

Thus the reality of any connexion existing between the tube
and the Malpighian body has been questioned and denied,
and still continues to be so ; as also the existence of a vibratile
epithelium in the upper portion of the uriniferous tube. The
first particular has been denied by Muller *, Reichert f, Ger-
lach and Bidder ; and the second has been doubted or denied
by Huschke, Reichert, and Bidder. On the other hand, the
observations of Schumlansky J, and A. Koelliker of Zurich
accord with those of Mr. Bowman on the first particular, and
those of BischofF, Valentin, Pappenheim, Gerlach, and Koel-
liker §, on the second, the latter observer describing the entire
epithelium of the tubes as ciliated.

It is so easy9 however, to satisfy ourselves, in the kidney of
every animal, of the reality of a connexion between the tube
and the Malpighian body, as well as of the presence of a cili-

* De Glandularum Secernentium Structura Peinitiori, Earumque
prima formatione in Homine atque Animalibus, Commentatio Anatomica.
Cum Tabulis sen. incisis xvii. Leipsiae, 1830.

f Bericht tiber die Fortschritte der Mikroscopischen Anatomie in dem
Jahre 1842 ; von K.B. Reichert, Prof, in Dorpat, Muller's Archiv, 1843.

j De Structura Renum, 8vo. 1788.

§ Ueber Flimmerbeweg-ungen in den Primordial Nieren, Archiv fur
Anatomie, Physiologic, und Wissenchaftliche Medicin, Heft V. S. 518
1845.

GLANDS. 439

ated epithelium, in the upper portion of the uriniferous tubes,
that it would be perfectly unjustifiable for observers again to
call these two points in question.

The statement of Mr. Bowman, which has met with most
opposition, is that made as to the entrance of the Malpighian
capillary plexus into the cavity of the true capsule. Some
observers have denied the correctness of this description, on the
simple ground of the anomalous position in which the blood
vessels would be placed, were such an arrangement the true
one. This objection, however, is insufficient to disprove the
accuracy of Mr. Bowman's explanation, since in the liver
there is every reason to believe that the vascular and se-
creting elements of glands are intimately associated. Again,
some observers, not satisfied with Mr. Bowman's description,
have given others.

Thus Gerlach * says that the Malpighian capsule is not, as
Mr. Bowman described it, a blind termination of a uriniferous
duct, but a retraction or introversion, a diverticulum of the
same structureless membrane which forms the uriniferous
tubes ; — also, te that when the Malpighian capillary network
is closely examined, after the capsule has been entirely de-
tached from it, we see it in its whole extent covered by a
thick layer of nucleated cells, which are continued from the
inner wall of the capsule upon the Malpighian vessels ; and
the latter lie introverted within a layer of cells, like an in-
testine within the peritonaeum." f

Gerlach 's description is assuredly incorrect : the views of
the structure of the Malpighian body, entertained by Bidder J,
although they approach more nearly to the truth, are also in-
accurate : he considers that the glomerulus, or vascular plexus,
is inserted or pushed into the expanded portion of the urini-
ferous canal ; this on its part embracing and surrounding the
glomerulus. According to this view the glomerulus would still

* Beitrage zur Stmcturlehre der Niere, von Dr. Joseph Gerlach, prakt
in Mainz (Mayence), Muller's Archiv, 1845.

t Edinburgh Medical and Surgical Journal, Oct. 1847.

I Ueber die Malpighischen Korper der Niere, von F. Bidder in Dorpat;
Muller's Archiv, 1845.

N N

440 THE SOLIDS.

be external to the cavity of the dilated extremity of the tube,
the relation between the two being comparable to the head
within the double night-cap.

The correct view of the structure of the Malpighian body
is, however, much more simple than either of those just de-
scribed. A Malpighian body, as already stated, consists of
the dilated extremity of a uriniferous tube, over which is
spread the Malpighian plexus : these two structures, viz. the
dilatation of the uriniferous tube, and the vascular plexus,
constitute all that is essential in the anatomy of the Mal-
pighian body : both are inclosed in a thick capsule : this is
not, however, a structure peculiar to the Malpighian body,
but a mere envelope, similar to, as well as a continuation of,
that which invests the tubes themselves.

A little reflection will show, that this view reconciles
many of the conflicting statements, made in reference to the
anatomy of the Malpighian body. The outer capsule referred
to, which is that spoken of by most other observers as the
true Malpighian capsule, is evidently that which Mr. Bow-
man had in view as the dilated extremity of the uriniferous
tube, and it is this which he described as being pierced by
the Malpighian artery, — a description literally and positively
correct.

The common envelope, which, however, as already stated,
forms no necessary part of the Malpighian body, is really
pierced by both the afferent and efferent vessels of that body,
as well as by the tube. (See Plate 60. fig. 3.) Mr. Bow-
man's error consists in having regarded this mere outer cover-
ing as the true dilated extremity of the uriniferous tube, which
it most certainly is not, and in having necessarily, as a conse-
quence, overlooked the true extremity of the uriniferous tube
with its contained epithelium.

Again, the confounding of this common envelope with the
true Malpighian capsule accounts for the assertions of those
observers who state that the uriniferous tube has no con-
nexion with that capsule: it has, indeed, no connexion by
continuity; it simply pierces it: of the inner or true capsule,
the uriniferous tube is absolutely a continuation.

441

The common envelope of the entire and perfect Malpighian
body differs structurally from the true capsule ; the latter is
thin and structureless, the former, thick, and constituted of a
delicately fibrous and nucleated form of elastic tissue.

Mr. Toynbee * is the only writer, with whose observations
I am acquainted, who understands the true character of what
is ordinarily regarded as the " capsule of the Corpus Malpi-
ghianum : " this he correctly describes as being a distinct glo-
bular investment, and not, as was supposed, an expansion of
the tube.

Notwithstanding, however, the knowledge of this fact, Mr.
Toynbee's views of the structure of the Malpighian body
appear to me to be far from correct.

Thus Mr. Toynbee describes the Malpighian body as " com-
posed of two distinct elements — a plexus of blood-vessels,
and a membranous capsule, which completely surrounds and
envelopes the plexus."

Each Malpighian body is indeed composed of two distinct
and essential elements, the dilated extremity of the uriniferous
tube embraced and surrounded by the Malpighian plexus :
the outer investment, called by Mr. Toynbee and others " the
capsule," is not a structure essential to the Malpighian body,
since it alike invests this and the uriniferous tube for its
whole length attached to it.

Again, Mr. Toynbee describes the uriniferous tube, after
penetrating the capsule, as twisting into a coil, and, after being
in contact with the ramifications of the corpus, as emerging
from the capsule.

This last statement shows that Mr. Toynbee was unac-
quainted with the proper character of the most important and
essential of the two elements of the Corpus Malpighianum,
viz. the dilated extremity of the uriniferous tube, filled with
its secreting cells.

* On the Intimate Structure of the Human Kidney, and on the changes
which its several parts undergo in Bright's Disease. By Joseph Toynbee,
F.R.S. June, 1846. Medico Chirurgical Transactions.

442 THE SOLID^.

Pathology.

The kidney would appear to be more liable to morbid
alterations than any other organ in the body ; nevertheless,
its pathology is still far from being completely understood,
notwithstanding that several observers have paid especial at-
tention to the subject. Several of the pathological conditions
of this organ appear to have been confounded together under
the common term " Bright's Disease."

A very frequent pathological condition of the secreting
cells of the kidney is that in which they are laden with glo-
bules of an oily fluid> similar to those which occur in the
hepatic cells in the affection commonly called fatty liver, or
fatty degeneration of the liver, but which would be more
correctly distinguished by the appellation of oily liver ; the
corresponding affection in the renal organ being known by
the name of oily kidney.

It is this condition of the renal cells which, in Dr. George
Johnston's* opinion, constitutes the true Morbus Brightii.

The large, smooth, and mottled kidneys are those in which
the oily matter abounds ; the smoothness, according to Dr.
Johnston, depending upon the uniform distribution of the
tubes in the cortical portion of the kidney with the oily
matter.

The wasted and granular kidneys, according to the same
observer, are those in which the accumulation of fat takes
place less rapidly and less uniformly; certain of the convoluted
tubes becoming distended with fat, forming prominent granu-
lations ; and these, pressing upon the surrounding tubes and
vessels, occasion their obliteration and atrophy, a wasting and
contraction of the entire organ being the -result. This con-
dition attends the more advanced stages of Bright's Disease,
and is the sequence of the first described form of the affection.

Dr. Johnston, from numerous examinations, has arrived at

* On the Minute Anatomy and Pathology of Bright's Disease of the
Kidney, and on the relation of the Renal Disease, to those Diseases of the
Liver, Heart, and Arteries with which it is commonly associated. George
Johnston, M.D. Medico-chirurgical Transactions, 1846.

GLANDS.. 443

the interesting and important conclusion, that the oily dis-
ease of the kidney is generally co-existent with a similar affec-
tion of the liver, and even with steatomatous deposition in
the coats of the arteries, and to a less extent with tubercular
deposit in the lungs.

Dr. Johnson also maintains the opinion, that the oily de-
position is not preceded by any inflammatory or congestive
stage : congestion accompanies the disease ; but this may be
either active or passive, and when the latter, is produced by
the pressure to which the vessels are subject in consequence
of the distention of the epithelial cells, and which pressure
gives rise to the effusion of serum and blood within the tubes.
These results are, however, the effects, and not the cause of
the disease.

The dropsy ensuing on scarlet fever, Dr. Johnson con-
siders, does not depend upon the presence of oil in the cells
of the kidney ; this dropsy, he regards as the result partly of
the cutaneous disease, and partly of the effort made by the
kidneys to relieve the skin, the circulation and functions of
which are so much impaired.

From experiments made on cats, it appears that confine-
ment in dark chambers has the effect of inducing granular dis-
ease of the kidney, accompanied by deposition of oil in the urine.

Dr. Johnson regards the existence of albuminous urine as
quite a secondary effect.

The results of Mr. Toynbee's investigation on the pathology
of Bright's disease are very different, as we shall presently
perceive, from those of Dr. Johnson: both observers, however,
agree in the statement that there can be no doubt that albu-
minous urine often exists, without any deposition of fat in the
epithelial cells of the kidney ; as in dropsy after scarlatina.

The following is Mr. Toynbee's own exposition of his re-
searches on the pathology of Bright's Disease : —

" The First Stage of the Disease. — In this stage the kidney is enlarged,
and innumerable black points are visible, which are the corpora Malpi-
ghiana dilated, and their vessels distended with blood, seen through the
capsule. The white spots which derive their appearance from the col-
lection of fatty matter, begin to be perceptible.

O O

444 THE SOLIDS.

" The peculiar features of this stage consist of an enlargement of the
arteries entering the corpora Malpighiana ; the dilatation of the vessels
of the tuft, the capillaries and the veins ; an increase in the size of the
capsule of the corpus and of the tubuli, and a large addition to the
quantity of the parenchyma of the organ.

" The condition of the arteries is visibly changed, even at this early
period ; the artery entering the corpus being actually twice or thrice its
natural size ; which is the case also with the Malpighian tuft, and the
capillary vessels which spring from the tuft. An injection, in this stage,
cannot very easily be made to pass through the tuft and fill the capsule
of the corpus, — a circumstance which almost always attends injection in
the later stages of the disease.

" The capillaries and veins are greatly enlarged, giving to the surface
of the organ the resemblance of net-work. This is the commencement of
the stellated condition, which is so marked a characteristic of the next
stage of the complaint.

" The tubuli in this stage are also much increased in their dimensions ;
but the fat which is found in them is soft and white.

" The Second Stage of the Disease. — The organ in this stage is very
greatly increased in size, its surface is smooth, and presents numerous
white spots ; the capsule is but slightly adherent to the surface, and the
tissue of the organ is flabby.

" The structural changes exhibited during this stage are the fol-
lowing : —

" 1st. The artery of the corpus Malpighianum becomes so greatly
enlarged that frequently it equals the dimensions of the tube itself, and
is eight or ten times its natural size. It is tortuous and dilated, and
sometimes, previously to entering the capsule of the corpus, presents swell-
ings analogous to those of varicose veins. The primary branches of it, in
forming the tuft, are also distended to ten or fifteen times their natural
size, and are not unfrequently discovered external to the capsule of the
corpus, as though thrust out by some internal force. The vessels
forming the tuft are likewise enormously enlarged, and very often the
minutest branches are fully as large as the main artery of the corpus in a
healthy state.

" Occasionally the tuft is broken up, and, instead of forming a compact
mass, exhibits its individual branches separated from each other. At
other times the branches of the tuft are actually larger than the primitive
artery of the corpus. Under these circumstances it is singular that Mr.
Bowman should have made the following remarks : — ' Though I have
examined, with great care, many kidneys at this stage of the complaint,
I have never seen, in any instance, a clearly dilated condition of the
Malpighian tuft of vessels :' he adds, 'on the contrary, my friend Mr. Busk,
an excellent observer, has specimens which undoubtedly prove these
tufts not to be dilated in the present stage: and I possess injected
specimens showing them in all stages, but never above their natural size.'

GLANDS. 445

It is very possible that the peculiar injection used by Mr. Bowman may
account for the fact which he mentions ; and this conjecture is rendered
extremely probable, as in the later stages of the disease, the Malpighian
tuft becomes pressed upon by the adipose accumulation within, and,
after undergoing compression, will permit the fluid used in the pro-
cess of double injection to pass through rather than yield and distend.
There are instances, again, in which the tufts are not enlarged, but appear
healthy, even in organs otherwise extensively diseased : but it is im-
portant to add that these tufts, both in the second and third stages, when
but slightly enlarged, or even not enlarged at all, will offer free passage
to the injection, on the most gentle pressure, without even distending the
whole of their vessels, and thus indicate their diseased condition.

" An enlargement of the renal arteries and dilatation of their branches,
are also observable in this stage of the disorder.

" The capsule of the corpus, too, is in this stage very greatly increased
in size, and during the process of injection becomes frequently filled with
the injection thrown into the arterial system.

" The tubuli differ considerably from their healthy condition, being en-
larged to two or three times their natural size, and aggregated together
in masses, so as to lie in contact with each other, and form definite,
roundish bodies : they are also extremely convoluted with numerous
dilatations ; frequently they are varicose. At other times they present
distinct aneurismal sacs, which bulge out from one part of the wall of the
tube, to which they are attached by a small neck or pedicle. Occasionally,
some of the vessels of a convolution are smaller than the others, and their
size nearly natural. The tubuli in the masses are so closely packed that
the blood-vessels are evidently compressed, and rendered incapable of
admitting an injection. At times, a tube, even at some distance from the
corpus, becomes very convoluted and knotted into a mass.

" Parenchyma. — In cases where the kidney is much enlarged, the pa-
renchymatous cells will be found not merely increased in size, but adi-
pose deposition will be visible throughout them.

" The Third Stage of the Disease. — The kidneys are smaller than their
natural size ; hard, white granules are prominent on their surface, which
is more or less lobulated ; the capsule is adherent ; vesicles of large size
are frequently everywhere interspersed, and numbers of smaller ones stud
the whole surface. On making a section, the organ is found to be de-
prived of blood ; the cortical part contracted, the blood-vessels large and
their walls thick.

"Arteries. — The arteries are in a more contracted condition than that
described in the second stage; and the Malpighian tuft is often so
changed from its natural state, that the greater part of its vessels are
not capable of being injected.

" The capsule of the corpus has assumed a more contracted appear-
ance.

o o 2

446 THE SOLIDS.

" The arteries in this stage are so difficult to inject, that some ana-
tomists have denied the possibility of the operation. The difficulty has its
origin in the great pressure, which is exerted on the whole of the arterial
system, by the contraction and hardening of the organ.

" Veins. — The veins in this stage present, on the surface of the organ,
the well-known stellated aspect which arises from the gradual pressure
exerted on the trunks, and the contraction of the organ.

Tubuli. — The tubuli are larger than in the preceding stage, and are
gathered into rounded masses, which form the granules on the surface of
the organ. The latter are of a white hue, and are most commonly fully
distended with fatty depositions ; though not unfrequently they appear
like dark spots ; the tubuli, in that case, being full of blood. A rounded
appearance is generally characteristic of the granules, in each of which
the component tubule forms innumerable convolutions. It is extremely
difficult to inject the tubuli from the ureter ; indeed, it is very rarely that
it is possible to distend them from this source ; nor is it an easy matter
to fill them from the artery, though, as will be seen by the drawings, my
efforts have not been without success.

The tubuli are filled with oily cells, granular matter, particles of various
sizes, and blood globules.

" Parenchyma. — The parenchyma is hard, and is composed of elongated
stellated cells, from the angles of which fine threads proceed, and com-
municate with each other."

The researches of Mr. Simon and Dr. Johnson, which ap-
peared simultaneously in the Transactions of the Medico-
Chirurgical Society for 1847, have brought to light other
facts in the pathology of the kidneys. It is proposed in the
next place to give an abstract of the observations of each of
these observers, couched, as far as possible, in the language of
the authors.

Mr. Simon's paper is entitled " On Subacute Inflammation
of the Kidney."

" Without dwelling on those excessively rare cases, where idiopathic
nephritis (independent of tubercles or of calculus) may, by its mere in-
tensity, have ended in large suppuration or (almost uniquely) in gan-
grene, I may state that, in an infinite majority of instances, inflammation
of the kidneys is subacute. It depends on some humoral derangement
of the entire system, and commences as functional excitement manifest
in an act of over-secretion. The morbid material which thus stimulates
the kidney in its struggle for elimination will sometimes consist of pro-
ducts of faulty digestion, — the lithates or the oxalates; sometimes of
matters cast upon the kidney in consequence of suppressed function in

GLANDS, 447

other organs — the skin, or the liver; sometimes will be the mysterious
ferment of a fever poison — typhus, or scarlatina. In these several cases,
whatever variety may exist in the detail of their causation, the essential
symptoms during life, and the essential anatomical changes, are strictly
identical in kind. They vary only in degree. The materies morbi seeks
to affect its discharge by means of an increased activity in the secreting
functions of the kidney : it stimulates it ; and the result of the stimula-
tion is not so much an increase of the watery secretion as it is an aug-
mented cell growth in the tubules of the gland. This acceleration of
function is incompatible with maturity of the secreted products; the
epithelial cells undergo various arrests or modifications of development,
and become more or less palpably imbued with evidences of inflam-
mation.

" If attention happen to be directed to the state of the urine, that
fluid will be found to present manifest signs of derangement. Micro-
scopical examination will show in it numerous nucleated cells, which, in
the hurry of over-secretion, have descended from the urinary tubules.
Many free cytoblasts will likewise generally present themselves, together
with a variety of those indefinite shapes, which are known to the Mor-
phologist as abortions of cell-growth, and which constitute a series of
connecting forms between the pus-globule and the healthy gland-cell.
Mingled with these, in greater or less quantity, will be noticed also those
remarkable fibrinous threads first described by Dr. Franz Simon in con-
nection with renal disease. They are seen as exceedingly delicate, almost
perfectly transparent and colourless cylinders, often containing in their
mass some of the cell-forms just enumerated, or, not unusually, a few
blood discs, resulting from haemorrhage into the tubules.

" On several occasions, where the renal irritation has been gouty, I
have seen crystals of lithic acid thus entangled in fibrin : in other cases,
though far less frequently, I have distinguished crystals of oxalate of lime
similarly enveloped. It is well known that these little cylinders are
fibrinous moulds of the inflamed urinary tubules, some of the other con-
tents of which they bring with them in their descent. They are thus
quite as characteristic of the disease they attend as croupy expectoration
is of tracheitis ; and the cells or crystals included in them often afford the
most valuable therapeutical indications.

" If patients chance to die while their urine is first furnishing the signs
enumerated, it will often happen that the kidneys, in their general ap-
pearance, present no marked deviation from healthiness. Their cortical
substance may, indeed, show the minute blood dots of intra-tubular
haemorrhage ; or, more rarely, may present here and there a pin-head
abscess. But often, perhaps most often, a superficial observer would pro-
nounce the kidneys healthy ; and, unless previous knowledge of the albu-
minuria had existed, they would receive no farther attention ; or the Case-
Book might contain that vaguest of all vague records — * slight con-
gestion of the'kidney.'

o o 3

448 THE SOLIDS.

" On minuter analysis, however, the microscope will reveal a large
amount of disease. The ultimate tubules are found, as one might antici-
pate, gorged with an uneliminable excess of crude and vitiated secretion.
Blood and amorphous matter, and an infinite range of cell-growth, from
pus globules to the healthy germination of the gland, present themselves
in various combinations ; and among them shape or colour will sometimes
enable us to discern the specific cause of the derangement — crystals of
lithic acid or of oxalate of lime, or the ochreous tinting of bile. By pro-
ducts such as these the tubes are plugged, irregularly distended, and
not unfrequently burst and annihilated. So close is the compaction of
material, even in many of those tubes, that have no shaped inflammatory
products within them, that they are plainly impervious ; and it is only
by artificial means, — by further tearing of the fragment, or by use of
chemical agents, that we can satisfy ourselves that the dense plug in
question consists but of agglomerated gland-cells.

" Now in the post mortem examination of these chronic cases, we may
or 'may not find the kidneys materially contracted and deformed. It
happens, to say the least, very frequently that the organ has preserved
its full size and presents the ordinary colours. Perhaps it may have a
cyst or two on its surface. Between such kidneys, and those which are
all knobbed and puckered and wrinkled, there is not the essential differ-
ence which first sight would suggest. I shall first detail the changes
which are latent in the healthier-looking kidney, and subsequently shall
consider the anatomy of the contracted specimens, and analyse the cir-
cumstances which determine that apparent atrophy of the gland.

" In the first instance, then ; In commencing the microscopical exami-
nation of the cortical substance, we partially find a similar state of tubes
to that described in connection with the sub-acute attack — a state,
namely, of unequal distention and of blocking up by their own accumu-
lated products. In the cases which have lasted a long time, these pro-
ducts will often be found to have undergone material alterations, from
the combined effects of pressure and absorption. The contents of the
epithelial cells will have lost much of their natural fine granularity ; so
that the cells will appear, even when viewed singly, to have acquired a
marked increase of solidity and substance. But, more than this — in
many parts hardly a trace of tubularity will be found ; the tubes have
been burst ; their contents have been interfused amid the matrix and
blood vessels ; and their debris may be found on opposite sides of a pre-
paration, — here black and bloated, there pale and collapsed.

" Betwixt these trophies of disease there is a new manifestation. The
interspace is crowded with a profuse development of cysts, apparently
foreign to the healthy structure of the part. They are of all sizes ; some
are visible to the naked eye ; some are of the magnitude of normal gland-
cells, Tg/w) 1000 ' kufc ^e maJOI>ity are °f an intermediate bulk,

GLANDS. 449

^i. Even where smallest, they are distinguished by their sharp
300 — oOO

outline ; and the larger ones are conspicuous by their roundness and
transparency, for all above r^; have predominantly fluid contents.

" To explain this very remarkable phenomenon, I take leave to digress
for a moment from the straightforward pursuit of the inflammatory
changes. Any one who has made a dozen post-mortem examinations must
have observed cysts in the kidney ; and there can be few pathologists
who have not speculated on the origin of these growths. Their connection
with chronic obstructive diseases of the kidney being notorious, some ob-
servers have supposed them to originate in dilatation of the Malpighian
capsules ; while others have referred them to distention of the urinary
tubules. They exhibit great variety in size ; they are seen every day as
small as mustard seeds ; they have been seen as large as cocoa nuts.
Thus, they obviously range from a very conspicuous largeness to a size at
which the naked eye loses them. On microscopical examination of
cysted kidneys, the same uninterrupted gradation of size is seen to repeat
itself. The larger vesicles fill the field of the microscope ; the smaller
ones diminish progressively, so that scores of them may be in the field
at the same time.

" A section of cysted kidney, carefully examined with a sufficient
magnifying power, may show an astonishing number of these minute
vesicles ; a number quite disproportionate to that of the larger cysts
visible to the naked eye ; so that, sometimes, by a single one of the latter
class seen on the surface of the kidney, I have found myself guided to a
disease which is substantially a vesicular transformation of the ultimate
structure of the gland. The smallest cysts are simple nucleated cells, of
the same size (or rather within the same limits of size) as the common
secretory, or epithelial cells of the gland. From these cells they seem to
be distinguished by their very definite outlines, and by their transparent
fluid contents : but a step further in microscopical analysis shows that the
distinction ceases at this point. They show no signs of a specific origin ;
no germs can be found for them other than might equally belong to
epithelial development ; it seems as though from the same germs — ac-
cording, no doubt, to varying influences — healthy gland-cells might
grow, or these fluid-holding cysts.

" Fuller investigation of the specimen reveals the following very sug-
gestive fact : — the copious formation of cells occupies the place of tubes,
holding their relation to the vascular plexus of the gland ; and, as one
gets to the periphery of the portion of gland thus transfigured, one finds
the broken extremities of the original tubules, — some empty and collapsed,
others^ obstructed and often dilated with morbid accumulation. In some
cases this obstructive material contains a large proportion of fat, or con-
sists of it almost entirely.

" In short, in pursuing the minute anatomy of the cysted kidney, we

o o 4

450 THE SOLIDS.

are conducted back to that same structural change which we found in
connection with sub-acute nephritis, and demonstrably dependent on
inflammatory processes ; or sometimes we are led to a change in some
respects similar to this, associated with what is known as the mottled
condition of the kidney.

" The pathology of cysted kidney may accordingly be traced in either
of two directions ; from its first causation, or from its extreme pheno-
mena. Following the latter course, we have ascended to a period in the
history of cysts, in which they lie with numberless gland-germs amid the
remnants of broken tubules. The unbroken tubules around show no
growth of such cysts in their interior ; many are distended, it is true,
but not with cysts ; their distention is of a kind that we have already
investigated, — inflammatory, or perhaps fatty. From the smallness at-
tained by the cysts, it seems quite obvious to me, that they cannot com-
mence in any transformation of the tubes themselves, or of the Malpighian
capsules. Accordingly, I find the same theory suggested by this method
of inquiry, as when the morbid change had been traced descensively
from its causes ; viz. that certain diseases of the kidney (whereof sub-
acute inflammation is by far the most frequent) tend to produce a
blocking up of the tubes ; that this obstruction, directly or indirectly,
produces rupture of the limitary membrane ; and that then, what should
have been the intra-tubular cell-growth continues with certain modifi-
cations as a parenchytic development.

" During the growth of the cysts, they frequently exhibit an endo-
genous formation of cells which line them as an epithelium.

" If I am right in my statement of facts, and if my theory of the cyst-
growth is sound, then the early stages of the process are certainly points
of great interest. For no one accustomed to the interpretation of nature,
can doubt the reparative tendency of these acts. The effused gland-
germs are the last phenomena of the original disease, and the first of the
attempted compensation. The transparent nucleated cysts, with their
clear sharp outlines, are not mere dropsical epithelia ; but are organised
for secretion into their own cavities, so as at least to withdraw from the
blood, if they cannot eliminate from the body, the materials which fill
them.

" Returning now to the traces of inflammation in an uncontracted
kidney, we have yet to ascertain the condition of its blood vessels.
Numbers of the Malpighian bodies are extinct for all purposes of secre-
tion ; their vessels obliterated, their capsules wrinkled round them ; they
are dwindled, opaque, and bloodless. Sometimes the contraction of the
Malpighian bodies is secondary on that rupture of their capillaries which
Mr. Bowman has indicated as the source of intra-tubular haemorrhage ;
which rupture, of course, may have arisen either in an augmented im-
pulse of the arterial stream which fills them, or in an impeded circu-
lation through the venous plexus into which they discharge themselves.
But rupture of the capillaries is not the only cause of atrophy, to which

GLANDS. 451

these bodies are liable in the disease under consideration. The vascular
tufts may be exposed to injurious pressure from materials accumulated in
their capsules. Thus I have seen them flattened into a fourth of their
natural compass, while the remaining larger portion of the capsule (pro-
bably continuous with an obstructed tubule) has been distended with a
colourless and transparent fluid.

" Such is the minute anatomy of a kidney, which, having suffused from
sub-acute inflammation, has undergone, in consequence, no noticeable
alteration of volume, although having in its interior a very considerable
new development.

" If the pathology of the uncontracted kidney be rightly understood,
that of the contracted specimen will follow it naturally. It seems to me
that, in the mere destruction and absorption of tissues, there is abundant
explanation of the shrunken dimensions of a kidney which has passed
through inflammatory changes. The tubes have burst, and a great
portion of their contents has been removed by absorption ; the Mal-
pighian bodies have dwindled to a few ; what, then, remains to make
bulk ? In the uncontracted specimen a false appearance of size is main-
tained by the adventitious cyst-growth, which I have described as filling
the interstices of the organ. But the cysts are so much over and above the
real kidney-structure ; and if that succulent surplus could be removed,
the result, as I have suggested, would be the falling together of wasted
textures into a comparatively small compass. The cause of shrinking in
the gland is the gradual absorption of spoiled material. This cause
operates equally in all chronic cases, and its effects are to be traced in
the uncontracted, as in the contracted specimen. The main difference
between these two lies in the more or less of interstitial cyst- development ;
the most dwindled are those in which least of the new growth has arisen
or has survived.

" I see no reason for believing that the interstitial effusion of lymph
effects much towards the final contraction of the kidney. There are not
wanting, I know, some pathologists who will assert it to be the great
agent in the change ; and who conceive they have seen the whole process
of fibre-formation, according to the most approved foreign cell-theories.
But I suspect that the observers of new fibre will often have confounded
cause and effect. Coincidently with atrophy of the kidney, there occurs
a contraction of the reticular matrix ; but that contraction is, probably,
consequent on a prior absorption of the intervening tissue. The meshes
of the matrix come nearer together, and, in a given space, there is an
excess of fibrous tissue, only because the material is withdrawn, which
originally expanded that matrix through three times the space it now
occupies.

" Up to the present point, I have studiously avoided introducing the
ambiguous and controversial name of ' Bright's disease.' And now it
will probably be asked, what relation to Bright's disease is borne by the
malady I have treated of. Is it the same thing under another name ? This

452 THE SOLIDS.

question can be answered in a word, only when it shall have been settled
what Bright's disease really is. The history of the complaint or com-
plaints, included under that title, was, perhaps, originally systematised
with too much haste. Starting from dropsy with albuminuria, and noticing
that two chief forms of morbid appearance corresponded to that symptom
(one, namely, where the kidney was large and mottled ; the other, where
it was contracted and knobbed, or irregularly granular), pathologists have
considered these two forms as representing the extreme stages of one and
the same disease.

" I must venture to express a doubt as to the justice of this generalisa-
tion. After investigating both classes extensively, I am convinced that
the mottled and the contracted kidney do, in almost every instance, belong
to different morbid actions, not to different stages of the same.

" The mottled kidneys, in an infinitely large proportion of cases, remain
large and mottled to the end.

" I have now little further to add : with respect to the symptoms of
sub-acute inflammation of the kidney, I will make one observation in
addition to those already embodied in my paper. The descent of epithe-
lium and its germs with the urine ; the presence of albumen there, and
sometimes of blood ; the little casts of the tubules, — sometimes wrought
of fibrin, sometimes of compressed epithelium; — these signs belong
equally to the sub-acute inflammation and to the scrofulous disease.
They are signals simply of renal irritation, whether from one cause or
the other, and I suspect they only attend the scrofulous disease at that
stage of its progress in which sub-acute inflammatory action is super-
added to the primary fatty degeneration. Dr. Johnson's accurate ob-
servation has enabled us, under most circumstances, to diagnose the two
classes from each other ; for, in the scrofulous disease there will be al-
ways seen, as he describes, more or less oil entangled in the fibrin ous
casts, or gorging the cells which descend in the urine ; a phenomenon
which does not belong to the pure sub-acute inflammation."

The following pages embrace the more important portions
of Dr. Johnson's communication, which is entitled, " On the
Inflammatory Diseases of the Kidney."

" In a paper published in the last volume of the ' Society's Trans-
actions,' I gave some account of fatty degeneration of the kidney, and
declared my intention to make the inflammatory diseases the subject of a
separate communication. On the present occasion, I purpose to bring
before the Society the result of some observations on this very interest-
ing and important subject.

" In the paper before alluded to, when referring to the condition of
the kidney, which occurs as a consequence of scarlatina, I stated that " it
is, in fact, an inflammation of the kidney, excited, like the inflammation
of the skin which constitutes the eruption of scarlatina, by the passage

GLANDS. 453

through the part of the peculiar fever poison ; and as the inflammation
of the skin terminates in an excessive development of epidermis, and a
desquamation of the surface, so the inflammation of the kidney excites
an increased development of the epithelium which lines the urinary
tubules : this material partly accumulates in and chokes up the tubes,
while part of it becomes washed out with the urine, and may be detected
in large quantities in that fluid by the aid of the microscope.

" To the account then given, which I believe to be essentially correct,
subsequent observations enable me to make some important additions.

" On a microscopical examination, the convoluted tubes are seen filled
in different degrees with nucleated cells, differing in no essential character
from those which line the tubes of the healthy gland. The chief differ-
ence between these cells, which are the product of inflammation, and those
which exist in health, consists in the former being generally of smaller
size and more opaque and dense in their texture. It is very interesting
and important to observe that, while the convoluted tubes are rendered
opaque by this accumulation of cells in their interior, the Malpighian
bodies are transparent and apparently quite healthy. The straight tubes
which form the pyramids also contain an increased number of cells ; but
there is reason to believe, that these cells are not formed in these portions
of the tubes, but that they are lodged there in their passage from the
convoluted through the straight tubes; the latter being merely ducts
leading into the pelvis of the kidney. Some of the tubes contain blood,
which has, doubtless, escaped from the gorged Malpighian vessels lying
within the dilated extremities of the tubes. There is no deposit outside
the tubes. The essential changes in the kidney are an increased ful-
ness of the blood-vessels, and an abundant development of epithelial
cells, differing slightly in general appearance, size, and consistence, from
the normal renal cells ; this increased cell-development occurring in those
portions of the urinary tubules, the office of which, as Mr. Bowman has
suggested, is to excrete the peculiar saline constituents of the urine,
while the Malpighian bodies, whose office is the separation of the water,
are unaffected.

" The condition of the urine in these cases, is clearly indicative of the
changes occurring in the kidney. After the urine has been allowed to
stand for a short time, a sediment forms, and, on placing a portion of this
under the microscope, there may be seen blood corpuscles, with epithelial
cells in great numbers, partly free and partly entangled in cylindrical
fibrinous casts of the urinary tubes ; and, very commonly, numerous
crystals of lithic acid are present. As the disease subsides, which, under
proper treatment, it usually does in a few days, the blood, fibrinous casts,
and epithelial cells, dimmish in quantity, and finally disappear; but
traces 'of the casts and cells are still visible some days after the urine
has ceased to coagulate on the application of heat or nitric acid.

" The casts and cells which appear in the urine, when the disease is sub-
siding, are such as have remained some time in the urinary tubes before

454 THE SOLIDS.

they have become washed out by the current of fluid poured into the
tubes from the Malpighian bodies : many of the cells entangled in these
casts have, consequently, become disintegrated and broken up into amor-
phous granular masses ; thus presenting appearances which I shall pre-
sently show are characteristic of the casts occurring in cases of chronic
nephritis. Such is the morbid anatomy of the kidney, and such are the
characters of the urine occurring as a consequence of scarlatina.

" To the form of renal disease here described as occurring in connection
with scarlatina, I propose to give the name of ' acute desquamative
nephritis?

" The next form of inflammatory disease, to which I would direct at-
tention, is one of great interest and importance. Two drawings by
Mr. Westmacott represent the disease in two different stages : one re-
presents a kidney in the earlier stage ; the other shows a more advanced
stage of the same disease. The kidney is never much enlarged ; in the
earlier stage, the size of the organ is natural, and the structure of the
cortical portion appears confused, as if from the admixture of some
abnormal product : there is also some increase of vascularity. As the
disease advances, the cortical portion gradually wastes ; the entire organ
becomes contracted, firm, and granular ; the pyramidal bodies remaining
comparatively unaffected even in the most advanced stages : simultaneously
with the diminution in size of the kidney, there is a decrease of vascu-
larity. These changes occur very gradually : the disease is essentially
chronic, having a duration in most cases of many months, and in some
even of several years. It is almost confined to persons who are in the
habit of partaking freely of fermented liquors ; it is very commonly seen
in those who have suffered from gout, and is not uncommon in those
who, having indulged freely in the use of fermented liquors, have yet
never had an attack of gout. It is sometimes, but I believe rarely,
met with in those whose mode of life has been strictly temperate and
abstemious. The symptoms usually attending the disease, are the fol-
lowing : — dropsy, which commonly is not excessive, often coming on
only in the most advanced stages, and sometimes being entirely absent
throughout the entire progress of the disease. The urine is commonly
albuminous: it seldom, however, contains a very large quantity of
albumen, and sometimes there is no coagulation on the addition of heat
or nitric acid. The urine is sometimes high-coloured and scanty ; but
in most cases, it is rather abundant, pale, and of low specific gravity —
from 1005 to 1010. In some instances, the quantity of urine is much
greater than in health, and this increased quantity of urine is secreted by
kidneys which are found after death to be contracted to one-third of
their original bulk. In urine of such low specific gravity, there is, of
course, a deficiency of the solid constituents, while the blood, which is
much changed and impoverished, contains an excess of these materials.

" On a microscopical examination of the kidney, the nature of the above-
mentioned changes is very clearly revealed, and, at the same time, the

GLANDS. 455

attending symptoms are satisfactorily explained. My account of these
phenomena will be rendered more intelligible, if I give the facts and their
explanation at the same time.

" On placing thin sections of the kidney under the microscope, some of
the tubes are seen to be in precisely the same condition as in a case of
acute desquamative nephritis ; they are filled and rendered opaque by
an accumulation within them of nucleated cells, differing in no essential
respect from the normal epithelium of the kidney : this increase in the
number, and this slight alteration in the character, of the epithelial cells,
are the result of the elimination by the kidney, of mal-assimilated pro-
ducts, which are being continually developed in these gouty and intem-
perate subjects, and which are not normal constituents of the renal
secretion.

" There must evidently be a certain limit to the number of cells which
can be formed in any one of the urinary tubes ; for, although some of
the cells escape with the liquid part of the secretion, and so may be seen
in the urine, as in a case of acute desquamative nephritis, yet, in many
of the tubes, the cells become so closely packed, that the further forma-
tion of cells is impossible, and the process of cell-development, and, con-
sequently, of secretion within that tube, are arrested. The cells, thus
formed and filling up the tube, gradually decay and become more or less
disintegrated. While these changes are going on in the convoluted
portions of the tubes, the Malpighian bodies remain quite healthy, the
Malpighian capsules for the most part transparent, and the vessels in
their interior are perfect. From these vessels, water, with some albumen
and coagulable matter, is continually being poured into the tubes ; and,
as a consequence of this, the disintegrated epithelial cells are washed out
by the current of liquid flowing through the tubes, so that, on examining
the sedimentary portion of the urine, we find in it cylindrical moulds of
the urinary tubes, composed of epithelium in different degrees of dis-
integration, and rendered coherent by the fibrinous matter which coagu-
lates amongst its particles. The appearance of these casts are quite
characteristic of this form of ' chronic desquamative nephritis.'

" There is reason to believe, that when the process of cell-development
and of secretion have once been arrested, by the tube becoming filled
with its accumulated contents, it never recovers its lining of normal
epithelial cells ; but, when the disintegrated epithelium has become washed
away from the interior of the tube, the basement membrane may be seen,
in some cases, entirely denuded of epithelium ; in other cases, a few
granular particles of the old decayed epithelium remain : and again, in
other instances, the interior of a tube, which has been deprived of its
proper glandular epithelium, is seen lined by small delicate transparent
cells, very similar to those which may sometimes be seen covering the
vessels of the Malpighian tuft.

"It now becomes interesting to ascertain what further change the
tube undergoes, after having lost its normal epithelium. It is quite

456 THE SOLIDS.

certain that, as a general rule, the Malpighian bodies remain unaffected,
both in structure and in their office of secreting the watery constituents
of the urine, until the whole of the disintegrated epithelium has been
washed out of the tubes. Of this there are two proofs ; the first is the
fact of a very long convoluted tube having its contents completely washed
out, and its basement membrane left quite naked : this could happen
only as a consequence of a current of liquid passing through the tube,
and there is no known source of such a current but the Malpighian
vessels : the second proof is still more convincing and satisfactory, and it
is this, — that a tube may often be seen entirely denuded of its epithelial
lining, and continuous with a Malpighian body, in the interior of which
the vessels are quite perfect.

" Now, a tube of this kind deprived of its lining of normal epithelium
has manifestly lost its power of separating from the blood the solid con-
stituents of the urine, while, the Malpighian vessels remaining unaffected,
the power of secreting water remains. Further, it appears probable not
only that the Malpighian body continues to secrete water, but that the
whole length of a convoluted tube thus deprived of its proper epithelium,
and either remaining naked or lined by delicate nucleated cells, such as
those which cover the Malpighian vessels — that the entire length of such
a tube becomes a secretor of water, which it abstracts from the portal
plexus of vessels on its exterior. This is rendered probable by the
appearance of the tube itself; and the probability is still further increased
by the fact of the tubes becoming, in some cases, dilated into cysts, which
usually contain a simple serous fluid, without any of the solid constituents
of the urine.

" It has long been supposed that the simple cysts, which are so com-
monly seen in connection with some forms of renal disease, are, in fact,
dilatations of the urinary tubes. I am not aware that any satisfactory
evidence has been adduced in confirmation of this opinion, but there are
some facts and arguments which appear to me abundantly sufficient to
prove the accuracy of the notion.

" 1st. The tubes thus denuded of their epithelium are often seen much
dilated. I have repeatedly seen them three or four times exceeding
their normal diameter. In some cases the dilatation is very sudden, so
that the tube assumes a globular form, and appears to bulge in the
intervals of the nbro-cellular tissue, in which the tubes are packed : in
some cases, too, the basement membrane appears thickened in proportion
to the dilatation of its cavity. Now, this process of dilatation having
once commenced, and the lower end of the tube becoming closed by a
deposit in its interior, or by pressure from without, there is no reason to
suppose that the process may not continue until a cyst as large as a pea
or a walnut is formed.

" 2ndly. But there are other facts which afford a very interesting and
remarkable confirmation of this notion. In a case of simple acute or
chronic nephritis, the quantity of oil in the secreting cells of the kidney is

GLANDS. 457

very small ; sometimes, indeed, none can be detected. But it frequently
happens that, after a tube has been stripped of its secreting cells in the
manner before mentioned, an accumulation of fatty matter occurs in its
interior, the denuded basement membrane becomes scattered over with
separate oil-globules, and these increase in size until they form masses of
fatty matter, having much the appearance of adipose tissue ; and such a
mass is frequently washed out from the tube, and may be detected in the
urine. This occasional filling of the tube with fatty matter is very in-
teresting in connection with the fact, that in some cases the cysts, which
are supposed to be dilated tubes, are also found filled with the same
material. In two cases, I have found a cyst as large as a hazel-nut, quite
full of oil, presenting all the characters of that seen in the tubes which
have lost their epithelium in consequence of chronic inflammation.

" The evidence, then, of the simple serous cysts being dilated tubes, is
the following: — 1st. That tubes are often seen much dilated and
thickened. 2d. As the inner surface of the tubes has the appearance of
being endowed with the power of secreting water, so the cysts usually
contain a simple serous fluid. 3d. As an accumulation of oil occasionally
occurs in the tubes, so the cysts are in some instances filled with the same
material. 4th. There is no reason to suppose that these cysts have any
other origin. It appears probable that the Malpighian bodies could not
become dilated into cysts, because an accumulation of liquid within the
Malpighian capsule would necessarily compress and obliterate the ves-
sels of the Malpighian tuft, and so would cut off the further supply of
fluid.

" Another change consequent upon the destruction of the cells which
line the urinary tubes is, a diminished supply of blood, and a gradual
wasting of the tube. I have already shown that there must be a close
connection between an increased development of epithelial cells, and an
increased afflux of blood to the part. This is well seen in a case of acute
desquamative nephritis, and, vice versa, a more or less complete de-
struction of the epithelial cells will be attended by a corresponding
diminished afflux of blood, and a consequent atrophy of the part affected.
In every kidney which has been the subject of chronic inflammation,
there may be seen tubes contracted in different degrees, as a consequence
of the destruction of their epithelial lining : in some instances, the base-
ment membrane becomes folded, and presents an appearance not very
unlike white fibrous tissue. As a consequence of this wasting of succes-
sive sets of tubes, there is a gradual diminution in the bulk of the cortical
portion of kidney, until, at length, the entire organ becomes small,
contracted, and granular. When a thin section of a kidney, thus atro-
phied, is placed under the microscope, there may be seen an abundance
of fibrous tissue ; and this has often been described as new fibrous tissue
developed during the progress of the disease ; whereas it is, in reality,
nothing more than the atrophied remains of the basement membrane of
the tubes, with the healthy fibrous tissue arranged in the form of a

458 THE SOLIDS.

net-work in which the tubes are packed, and which now appears more
abundant in consequence of the wasting of the tubes.

" It has already been stated that the Malpighian bodies are unaffected
in the progress of this disease ; and this is true, in so far as they re-
main, for the most part, free from any deposit or accumulation in their
interior : but they must necessarily be affected by the changes occurring
in other parts of the organ. Thus the destruction of many of the Mal-
pighian bodies is a necessary consequence of the simultaneous wasting of
the vessels and tubes which occurs in the advanced stages of chronic
nephritis : and, during the progress of the disease, the vessels of the
Malpighian tuft will be in a state of more or less active congestion, in
proportion to the rapidity of secretion and of cell development in the
tubes ; and one consequence of this congestion of the Malpighian bodies
will be the escape of serum into the tubes, and the mixture of albuminous
matter with the urine. The quantity of albumen in the urine will be
great in proportion as the disease approaches in activity to that form
which I have called * acute desquamative nephritis.' When the disease
is chronic and inactive, there may be no albumen in the urine, or, it
may be present in quantities so small as not to be detected by the
ordinary chemical tests. In such cases, as, indeed, for the accurate
discrimination of all forms of renal disease, the microscope will be
found an invaluable aid. It must be remembered that the essential
change in this disease is a destruction of the epithelial cells in the
manner already described ; the best evidence of this change being in
progress is, the presence in the urine of moulds of the urinary tubes,
composed of more or less disintegrated epithelium ; and such evidence
I have repeatedly obtained, when no albumen could be detected by the
ordinary heat and nitric acid tests.

"A sufficient explanation has already been given of the small quantity
of the saline constituents excreted by the kidneys in cases of chronic
nephritis. It is manifest, that, if the epithelial cells are the agents by
which the solid constituents of the urine are separated from the blood,
a deficient excretion of these materials will be a necessary consequence
of the greater or less destruction of the epithelial cells.

" Before concluding this communication on the inflammatory diseases
of the kidney, it appears desirable to allude very briefly to the subject
of my last paper, — viz. ' Fatty Degeneration of the Kidney ; ' my object
being to show how essentially distinct are the two forms of disease ;
and, at the same time, to explain the manner in which they are some-
times combined.

" For some months past, I have been aware that fatty degeneration of
the kidney occurs in two distinct forms.

" In the simple fatty degeneration of the kidney, all the tubes be-
come almost uniformly distended with oil. In a slight degree and in the
earlier stages, it is often found, after death, in cases where there is no
reason to suspect that it has been productive of any mischief during life :

GLANDS* 459

it is not until the fatty accumulation has attained a certain amount,
that the functions of the kidney are interfered with. It is this form
of fatty degeneration of the kidney which occurs in animals, as a con-
sequence of confinement in a dark room. In the human subject, al-
though in the earlier stages it is a very common occurrence, yet in the
more advanced stages it occurs less frequently than the second form
of fatty degeneration. This form of the disease is represented in the
5th figure of Dr. Bright's 3d plate, as well as in the 1st, 2d, 5th, and
6th figures of Rayer's 8th plate. The cortical portion of the kidney, to
use the words of Dr. Bright, is soft and pale, and interspersed with
numerous small yellow opaque specks. The kidney is generally en-
larged ; sometimes it is even double the natural size. In some cases, the
cortical portion is somewhat atrophied and granular; but neither in
this, nor in the first form of fatty degeneration of the kidney, does that
extreme wasting with granulation occur, which is so frequent a conse-
quence of chronic nephritis.

" On a microscopical examination, the convoluted tubes are found
filled in different degrees with oil ; some tubes being quite free, while
others are ruptured by the great accumulation in their interior. The
opaque yellow spots scattered throughout the kidney, are neither more
nor less than convoluted tubes distended, and many of them ruptured
by their accumulated fatty contents ; just as the red spots are found to
be convoluted tubes filled with blood. The cells which contain the oil
are for the most smaller, more transparent, and less irregular in their
outline than the ordinary healthy epithelium; they are increased in
number, and many of them are so distended with oil as to appear quite
black. In parts of the same kidney, there may commonly be seen some
of the appearances already described as indicative of desquamative
nephritis. This form of disease is very commonly combined with fatty
degeneration of the liver ; but less frequently than is the first form of
fatty degeneration of the kidney.

" The peculiarities of the second form of fatty degeneration of the
kidney result from a nephritic condition of the organ, dependant on the
presence of some irritating material in the blood being associated with a
tendency to fatty degeneration ; this tendency resulting from the pre-
sence in the blood of mal-assimilated fatty matter. The nephritic con-
dition is manifest by an increase in the number of epithelial cells ; the
tendency to fatty degeneration, by a filling of many of these with oil.
Although the two conditions are combined in this and in similar cases, it
must be remembered that they are essentially distinct in their nature and
origin. Each cell which escapes from the kidney carries with it a por-
tion of the morbid material. The oil is in the form of visible globules ;
while the cells which contain no oil doubtless contain some other
material which is invisible, or less readily seen than the oil globules.

" I have now distinguished and described four conditions of the
kidney : —

P P

460 THE SOLIDS.

" 1st. Acute desquamative nephritis :

" 2d. Chronic desquamative nephritis :

" 3d. Simple fatty degeneration : and

u 4th. A combination of fatty degeneration with desquamative nephritis.

" The diagnosis of each of these conditions of the kidney, during the
life of the patient, is a matter of the greatest importance with reference
to prognosis and treatment ; and the diagnosis may be made with ease
and certainty by a microscopical examination of the urine."

The most recent researches in this country into the patho-
logical anatomy of the kidneys are those of Dr. Gairdner *,
who has evidently devoted to the elucidation of this subject
not a little time and attention ; and the results of these in-
vestigations will now be given in as concise a form as
possible.

Dr. Gairdner treats of his subject under the three following heads : —
1. Exudation: 2. Lesions affecting chiefly the vascular system: and
3. Lesions of the tubes and epithelium — an arrangement which will here
be followed.

Exudation.

Exudations into the substance of the kidney give rise to a great
variety of external appearances, which have been well figured and de-
scribed in the works of Bright and Rayer.

Exudations from the blood-vessels may have their seat in any, or all
the tissues of the kidney ; their usual situation, however, is in the in-
terior of the tubes, but it also occurs frequently within and around the
Malpighian bodies, and in the intertubular tissue, the tubes being quite
clear ; it is also seen infiltrated through all the tissues in the form of a
homogeneous mass, which contained within it the whole of the anatomical
elements of the kidney.

The appearance of the kidney, as altered by the presence of exudation
in the tubes, is subject to variations depending on the amount of the
deposition, and its partial or general character : one almost invariable
effect of the repletion of the tubes, is a corresponding diminution in the
fulness of the vessels of the cortical substance, particularly of the Mal-
pighian vessels, and the capillaries surrounding the tubes. This effect is
evidently the result of pressure.

It is thus evident that Dr. Gairdner does not ascribe the albuminous
urine of Bright's disease to secondary congestion, or rupture of the
Malpighian bodies, caused by the distention of the tubes from accu-

* Contributions to the Pathology of the Kidney, by William T. Gaird-
ner, M.D. Monthly Journal of Medical Science, 1848.

GLANDS. 461

mulated fat ; and in this particular his views differ from those already
cited of Dr. George Johnson.

The volume and weight of kidneys containing exudation in the tubes
are frequently much increased.

The exudation may be diffused throughout the organ, or it may be
confined to certain portions of it. " It then tends," writes Dr. Gairdner,
" to accumulate in certain sets of the convolutions in which the urinary
current is least active. These becoming partially blocked up, and ceasing
entirely to secrete, are thrown aside from the outward current of se-
cretion, and become a centre of attraction for further deposit, just as
the eddies arid still waters at the sides of a rapid stream receive from
it the foam and floating bodies brought, down from above. In this way,
more and more of the adjacent loops of tubuli are filled with the ab-
normal deposit, and become added to the former nucleus, until the
masses of exudation, thus imprisoned within tubules through which no
secretion passes, form irregularly rounded bodies in the cortical sub-
stance, visible to the naked eye, more or less prominent on the surface of
the organ, and usually of an opaque -yellowish colour. These are the
granulations first described by Dr. Bright."

Intratubular exudations, excluding tubercular and cancerous deposits,
may be considered under three heads : «, crystalline or saline matters
deposited from the urine ; b, oleo-albuminous, or granular exudations
from the blood plasma ; c, exudations forming pus.

a. The most common saline deposit met with in the tubes of the
kidney is the amorphous urate of ammonia ; inasmuch as this salt is a
constituent of healthy urine, its presence in moderate quantities is
merely a normal post-mortem appearance, the deposition of the salt
resulting from the cooling of the urine after death. In some instances,
however, it is present in such large quantities ; and in these it occasions
such an alteration in the appearance of the kidney, that it might, unless
discriminated by means of the microscope, be attributed to disease.

Under the microscope, the urate of ammonia presents the appearance,
when within the tubes, of a fine molecular shading, which entirely ob-
scures the nuclei ; the distinguishing character of this deposit is its
ready solubility in the dilute acids, as the acetic or nitric.

In one case Dr. Gairdner detected the presence of crystals in the tubes,
which, from their appearance and colour, he entertained little doubt
were of uric acid, although, from their minute quantity, they could not
be submitted to chemical examination.

In this case the urine was of low specific gravity, and albuminous,
although there was no apparent exudation within the substance of the
gland.

b. Dr. Gairdner includes under the term " oleo-albuminous exuda-
tions from the blood plasma," those exudations which are fatty in their
nature, as well as the inflammation globules, granular corpuscles, or
exudation granules, and corpuscles of different writers.

p p 2

462 THE SOLIDS.

The facts connected with the presence of fatty exudations in the
kidney, have been almost exhausted by the excellent researches of Dr.
Johnson ; one additional fact of interest has been added by Dr. Gairdner.
This observer finds that the fatty granules or globules are not confined
to the epithelial cells, but also that they may be freely disseminated
throughout the tubes : the tubes containing the fatty granules sometimes
appear distended, at other times smaller than natural, as if they had
contracted around the fat.

It is probable that the presence of the fatty globules in the tubes
results from the rupture and disorganisation of the cells which first con-
tained them, and that, therefore, their location in the tubes themselves
indicates a more advanced condition of this form of renal disorganisation.

c. The occurrence in the cortical substance of deposits of pus is not
very uncommon : their most usual form is that of small abscesses, rarely
exceeding the size of a pea, and frequently much smaller ; sometimes con-
fluent, and irregularly disseminated throughout the cortical substance.

The granular (oleo-albuminous) form of exudation is frequently found
occupying the tubes of the kidney, and occasionally also within the
capsules of the Malpighian bodies : when in large quantity in the
latter situation, the tuft of vessels becomes compressed, shrunk, and, in
most cases, invisible.

Under the heading " Partial distribution of the oleo-albuminous ex-
udation," Dr. Gairdner describes, in the following terms, a peculiar
pathological condition of the kidney: — "I have already described the
formation of granulations as dependant on the accumulation of deposit
in particular groups of tubules in the cortical substance. In such cases,
however, the affection is probably, at first, general ; they are very dif-
ferent from the form now to be described, in which the deposit is quite
limited in extent, and isolated.

" There are occasionally met with, on removing the capsule from
the surface of a kidney, irregular patches, of a paler colour than the
rest of the organ, sometimes a little elevated, sometimes depressed below
the general surface. Their boundary is quite abrupt, and they are fre-
quently surrounded by a well-marked rose-coloured areola, extending
more or less into the surrounding substance. On making a section of
these patches, they are found to penetrate into the cortical substance,
and sometimes even a certain way into the pyramids. The vascular
areola, when present, extends round them in every direction, and is
found, on examination, to consist of highly-injected Malpighian bodies
and capillaries, with or without extravasation ; the colour of the patches
varies from yellowish-grey to gamboge-yellow : their consistence is ge-
nerally firm. On microscopic examination, they present a large amount
of exudation, varying from the molecular to the large granular form.
In some cases the tubes may be seen filled with exudation ; in others
they appear to be in great part obliterated. In one case I found the
Malpighian bodies quite free of exudation ; they preserved their usual

GLANDS. 463

arrangement, and were readily discoverable by a simple lens on the sur-
face of the section. The parts of the kidney not involved in the deposit,
generally present no abnormal appearance."

Lesions affecting chiefly the vascular system.

Variations in the vascular condition of the kidney may, and frequently
do exist, totally unconnected with organic change : thus this organ, like
all other vascular structures, may be either in a hyperemic or anaemic
state ; and these conditions may effect either the entire vascular system,
or they may be local only, or they may involve respectively the venous or
arterial vessels. The veins of the kidney are disposed chiefly in two
situations, viz., on its surface, and in the substance of the pyramids, the
cortical substance containing but few veins. On the surface the larger
vessels follow a somewhat stelliform arrangement, while the capillaries
themselves form a meshwork, the meshes describing small pentagonal or
hexagonal spaces, in each of which a single convolution of a tube is
situated. The state of these vessels is subject to much variation ; they
may be in an anaemic condition, and scarcely visible, or they may be
gorged with blood ; in some instances this engorgement is general, and
in others it is confined to the stelliform vessels just referred to. These
conditions, as already observed, may be totally unconnected with dis-
ease ; when, however, there is great irregularity of injection, amounting
to marbling of the surface, and great increase in the size of the stellar
vessels, these are generally pathological, and result either from partial
obliteration of the venous network, or of the extrusion of the blood from
it, through over-distention of the loops of tubuli which form the inter-
vening pale spaces.

" The engorgement of the capillaries and Malpighian tufts gives rise
to two conditions : first, a generally diffused heightened colour of the
cortical substance ; and second, increase and greater distinctness of the
vascular striae, running from the base of the pyramids to the external
surface. This latter species of injection often exists to a great extent,
without any corresponding injection of the rest of the kidney, and in
some instances the red points composing the striae are so much increased
in size as to form considerable petechiae (one line in diameter, or up-
wards), in which case the petechiae usually extend to the surface, oc-
cupying the intervening spaces of the venous polygons above mentioned.
This appearance was supposed by Rayer to occur from simple hyper-
trophy and vascular injection of the Malpighian bodies ; but Bowman *,
who has shown that the Malpighian bodies do not exist on the surface
of the kidney, has also given a better explanation of such petechiae,
which he holds to arise from rupture of the Malpighian tuft, with extra-
vasation of blood into the surrounding tubes. He argues that the

* Philosophical Transactions, 1842.
p r 3

464 THE SOLIDS.

petechias are of irregular form, and of much larger size than the Mal-
pighian bodies have ever been observed to acquire. He gives, also, a
figure representing the occurrence of a similar appearance, from artificial
injection, at the surface of the kidney. In this figure the loops or
knuckles of the tubuli are seen filled with injection, presenting them-
selves at the surface, and surrounded by the venous network."

The correctness of this explanation cannot be doubted ; and it is
therefore evident that the occurrence of these petechiae must be con-
sidered as invariably morbid.

The anaemic condition of the kidney, when the result of disease, is
generally accompanied by increase in the size of the tubes from contained
secretion ; and it is the pressure of these on the surrounding vessels that
occasions their empty condition, and, in some instances, even obliteration.
The vessels of the Malpighian tufts likewise become involved, and the
Malpighian corpuscles themselves, thereby altered in form, from being
globular they become angular and compressed.

Under the heading " Congestion followed by permanent obliteration of
the Capillaries," Dr. Gairdner has described a lesion of the kidney, which
he has designated by the term " waxy degeneration" in contradistinction
to the "fatty degeneration"

" The appearances most characteristic to the naked eye of this form of
lesion, are those so admirably figured and described by Rayer as the
second form of his * nephrite albumineuse.' The kidneys are generally
increased in size, sometimes very remarkably so. Their consistence
varies : they are sometimes more flaccid than in the natural condition,
but always preserve considerable tenacity. The surface is either quite
smooth, or more or less depressed and furrowed. The venous vascu-
larity assumes, to a considerable extent, the stellate form ; the polygons
are mostly absent ; and the extreme irregularity and abruptness of dis-
tribution of the superficial veins gives to the surface a variegated or
' marbled ' appearance, which is quite characteristic of this stage of the
affection. (See Rayer, Plate VI. figs. 2, 3. 5 ; Bright, Plate II. fig. 1.)
Occasionally, also, amid this unequal injection, there are to be found
scattered petechiae, indicating recent extravasations of blood into the
tubes. On section, the cortical substance has considerable volume, and
presents a smooth, glistening, almost semi-transparent appearance, which
cannot be better distinguished than by the term waxy. It may partake
in a slighter degree of the variegated character of the surface ; more com-
monly it is of uniform appearance, and of a yellowish or fawn colour,
sometimes verging into a pale flesh tint. The vascular strias of the cor-
tical substance are generally to be traced by a more or less distinct in-
jection, and a few injected Malpighian bodies, or petechise of extrava-
sation, are sometimes dispersed through the section. (See Rayer, Plate X.
fig. 3.) In other cases, a little further advanced, both the strise and the
Malpighian bodies are nearly destitute of blood. (Rayer, Plate X. fig. 1 ;
Bright, Plate Tl.fg. 1.) The pyramids frequently retain their normal

GLANDS. 465

vascular! ty ; sometimes, however, they are of a pale colour and their
bases are indistinctly marked, — a condition which indicates the progress
towards a further disorganisation.

" When a kidney in this condition is carefully and minutely injected,
the greater proportion of the cortical substance remains impervious ;
the injection, however, can frequently be made to penetrate as far as the
cortical stria?, and even to some of the Malpighian bodies. (See Rayer,
Plate X.Jig. 2 ; Bright, Plate II. Jig. 3.)

" From these circumstances it is obvious, that the lesion above described
consists in an obliteration or obstruction of the capillary system of vessels
throughout the organ, and a partial obliteration of the veins on its surface.
There is also every probability that this condition is secondary to one in
which there is a high degree of congestion of the organ. The extrava-
sations, the occasionally injected Malpighian bodies, and the highly in-
jected though partially distributed stellar veins, leave no doubt that the
state of congestion described as tha first form of albuminous nephritis by
Rayer, is really the antecedent of the present or second from.

" To any one who is familiar with the marbled and waxy kidney here
described, there can be no difficulty in recognising a further stage of the
same lesion, in which the organ is perfectly pale both on the surface and
on section, with the exception perhaps of a very few stellated superficial
veins. The kidney in this stage (the transition to which seems to be re-
presented in Rayer, Plate VI. Jig. 4.) is still heavy and voluminous ; it
acquires additional firmness and elasticity, and assumes much of the
general appearance of a true non- vascular texture. It varies from a
light yellow to a fawn colour, which extends to the pyramids, the bases
of which become still more confused and intermingled with the cortical
substance than in the marbled kidney. The capsule is frequently more
firmly adherent to the external surface than in health.

" From the pale and yellow appearance of the kidney in this stage, it
is very apt to be mistaken, even by a practised eye, for an extreme de-
gree of the fatty degeneration. A well-marked example, indeed, will
hardly give rise to this error, if attention be directed to the degree of
firmness of the organ, the peculiar lustrous character of the cut surface,
and the entire absence of the opaque granulations of Bright, or of that
dull tint which distinguishes the excessive degrees of the fatty disease.
The appreciation of these characters is, however, more difficult where, as
sometimes happens, exudation is also present ; and the distinction which
has escaped the acute observation of M. Rayer, has undoubtedly been
overlooked by many other observers.

" The microscopic characters of this lesion are chiefly negative. There
is not unfrequently an entire absence of exudation ; indeed, in the most
market! cases of the lesion I have seldom found even the slightest trace
of any abnormal deposit. Occasionally, however, there is a very minute
quantity of fatty exudation in the tubes, generally in very small granules,
and scattered throughout the organ. The tubes are either natural, or in

p p 4

466 THE SOLIDS.

the advanced stages pass into some of the states hereafter to be described.
The capillary vessels surrounding the tubes are not visible, and in their
place there is fibrous tissue, which in this form of lesion always appears
somewhat exaggerated. The Malpighian bodies are also frequently seen
in process of obliteration, and surrounded by dense capsules of fibrous
tissue. The epithelium is frequently altered in character, but its changes
follow no fixed rule.

" The absence or scantiness of exudation, taken in connection with the
extent of degeneration appreciable by the naked eye, are amply sufficient
characters to distinguish this lesion from the extreme stages of the fatty
disease."

Lesions of the Tubes and Epithelium.

Some of these lesions have been already described under the head of
exudation ; but there are others which are not less important than those
formerly alluded to, and which are very frequently found in connection
with them.

Imperfect Development of the Epithelium Cells and Nuclei. — The epi-
thelium cells and nuclei vary in size and characters within certain limits
even in healthy kidneys ; the nuclei less so than the cells themselves ; but
in all kidneys, whether healthy or diseased, the nuclei which are most
closely adherent to the basement membrane are less perfectly circular,
and of considerably smaller size, than those lining the tubes and sur-
rounded by complete cellrwalls.

Those acquainted with the normal anatomy of the kidney will be able
to determine the limits of variations in the epithelium and nuclei com-
patible with a state of health.

In very many pathological conditions of the organ, the nuclei occur in
various places almost wholly devoid of cell-walls. They may be more
abundant or more scanty than usual ; and often appear in great profusion,
huddled together in confused masses, and mixed with shreds of membrane
and amorphous molecular matter, not soluble in acetic acid. This ap-
pearance of debris, which no doubt results from disintegration of the
cell-walls, most frequently occurs in kidneys which are abnormally soft
and large, and from the cut surface of which an unusually large quantity
of turbid whitish juice may be scraped. Such softened and altered kid-
neys occur frequently in fever and other diseases.

A more unequivocal pathological change (often occurring along with
the above) is the small size and altered form of the nuclei throughout
the organs, these not being more than half the usual size and always des-
titute of cell- walls. Sometimes they float scattered and solitary in the field
of the microscope ; at other times they appear aggregated together either
by twos or threes, or in much greater numbers, the connecting medium
being a transparent and filmy substance, the nascent or undeveloped
cell-membrane which has separated from the basement membrane, along

GLANDS. 467

with the hall-developed or young nuclei above described. These aggre-
gations of young nuclei are sometimes mingled with the amorphous debris
of effete epithelium or with granules and molecules of oleo- albuminous
exudation, or of lithate of ammonia, which communicate to them a dark
and confused appearance : not unfrequently, also, these masses, when
freed from the tubes, retain more or less of their form, and present so
exactly the appearance of the casts of the tubuli seen by Franz Simon,
and many other observers, in the urine, as to leave no doubt of their
identity with these bodies.

Desquamation of the Epithelium. — The changes above described are
generally accompanied by an extremely rapid generation of nuclei, which
are separated from the basement membrane in an imperfect state, and
carried away along with the urine, in which they may be readily detected.

In some cases of desquamation of the epithelium, it is scarcely possible
to recognise any departure from the usual condition of the kidney, either
with or without the assistance of the microscope. The degree of vascu-
larity is very various in different specimens, and the epithelium thrown
off is so quickly resupplied, that there is no very observable change in
the microscopic condition of the tubules. In one very intense case, in
which ten pounds of very watery urine loaded with an epithelial sediment
were passed daily for some weeks before death, the kidneys were small,
flaccid, and bloodless ; many of the tubes were quite full of nuclei closely
heaped together ; some of the nuclei were under-sized ; the cells, when
entire, were much compressed and angular. In another instance where
urine was passed in large quantity and full of epithelial debris, during
the last two months of life, the kidneys were found in an opposite condi-
tion, viz. large and congested, and with a firmness and smoothness of
section like the first stage of the waxy degeneration formerly described.
In this case, the condition of the tubuli was in most parts quite natural;
in some, however, there was extravasated blood, and in others the epi-
thelium had accumulated in abnormal quantity. In both these cases
there was imperfect development of the epithelium, but cases have
occurred to me in which this character was by no means well marked :
the crowding of the tubes with nuclei, although frequently found in the
earlier stages of desquamation, is not invariably present ; and the tubes
were even seen to be gorged with epithelium in a case where none had
been separated from the urine for weeks before death.

So long, therefore, as the epithelium is freely regenerated, the kid-
neys may present a tolerably healthy appearance, even on minute
examination : after prolonged disease, however, further changes take
place ; the epithelium becomes more sparingly generated, and is thrown off
in the Coherent masses above described, leaving the basement membrane
in portions bare, or with a few scattered oval nuclei, much smaller than
those cast off, adhering to its inner surface. In the microscopic examin-
ation of organs in this condition, there are frequently seen films of such
exceeding delicacy and transparency as to be only visible by very care-

468 THE SOLIDS.

ful management of the light : they preserve the shape of the tubules,
and contain no nuclei or structures of any kind. Similar films are
occasionally seen in the sediment of urine. They are probably thrown off
from the denuded basement membrane.

" Obliteration of the Tubes. — The basement membrane, which, with the
few closely adherent oval nuclei above described, is now the sole remain-
ing structure of the tubes, soon undergoes a change. It loses the
cylindrical form proper to it in the fresh and natural kidney, and becomes
flattened by the pressure of the surrounding parts. Its cavity is thus
obliterated, and what was a tube assumes the appearance of a transparent
riband, dotted here and there with small oval nuclei, which, when seen
at the edges, appear to be inclosed between two layers of membrane.
These riband-shaped portions of membrane appear to present consider-
able tenacity and elasticity ; by their greater density, and by the con-
stant presence of the small oval nuclei so often mentioned between their
layers, they are in most cases readily distinguished from the delicate
films which have been referred to above. They are very various in
diameter, but are always inferior in this respect to the normal tubes ;
and they appear to break up spontaneously into smaller portions-, each
of which contains from one to six or more nuclei : these portions are of
various sizes ; they are usually broadest in the middle, and taper to a
point at both ends. The smallest of them contain only a single nucleus,
and present an appearance in every respect like that of young fibres of
areolar texture, or those fusiform cells, which have been called fibro-
plastic. I think it probable that the whole of the diseased basement
membrane ultimately splits up into fibres of this kind. While these
changes are proceeding, the capillary vessels, which have ceased to be
subservient to secretion, are usually obliterated: the consequence of
this double obliteration of vessels and tubes is a considerable degree of
atrophy in the diseased parts ; and as the atrophy takes place at first
chiefly in the cortical substance, great irregularities of the surface
generally supervene : thence arises the appearance so well described and
figured by Dr. Bright (Plate III. fig. 2.), in which, from the atrophy
of the cortical substance, the bases of the pyramids ' are drawn towards
the surface of the kidney.'

" When oleo-albuminous exudation supervenes on the above derange-
ment of the tubes, or when desquamation supervenes on the former
(circumstances which I conceive to be of very common occurrence), the
exudation most commonly takes the form of the granulations of Bright,
which are deposited chiefly in the diseased tubes ; and the atrophy pro-
ceeding around these, they become salient, and the surface generally
irregular, giving rise to the tuberculated state of the surface so common
in all the later stages of the granulated kidney. (Bright, Plate III.
fig. 1 ; Rayer, Plate VII. fig. 6. Plate IX. fig. 8.) As the atrophy,
however, proceeds, the granulations are gradually absorbed ; and when

GLAN£>S. 469

the kidney lias become extremely contracted and irregular, they often
in part disappear.

" The atrophied portions of the kidney are usually exsanguine, and
of a tawney or drab colour : they have considerable hardness and
toughness. Examined microscopically, they appear to consist of fibres
and fusiform cells in great abundance, and more or less granular exuda-
tion, according to circumstances. According to Henle, Eichholtz, Gluge,
and others, these fibres are in great part new formations ; Johnson and
Simon consider them as nothing more than the compressed parenchyma
of the gland, from which all the other normal elements have disap-
peared. I look upon them as formed in great part by the breaking
up of the basement membrane of the tubes (as above described), as well
as from the parenchyma and obliterated capillaries. It is not im-
probable, however, that, in addition to these elements, some new fibrous
tissue is formed.

" The extreme stage of the atrophied kidney is nearly the same,
whether exudation have existed or not.

*' Microscopic Cyst-formation. — It occasionally happens, on examining
the section of a kidney with the microscope, that we see scattered through
some parts of the section a few small clear vesicles, of nearly circular or
oval form : they are either of a very pale straw colour, or nearly colour-
less, and are perfectly clear and translucent, with a very distinct sha-
dowed margin, which causes them to stand out in bold relief from the
other textures composing the section. Their diameter is usually from
^th to -^th of a millimetre, but in this respect they vary considerably ;
sometimes they appear to lie in the tubular areolae, and at other times to
be unconnected with these. Very rarely they have appeared to contain
a few granules ; most commonly, even when there is granular exudation
around them on every side, they contain nothing but clear fluid. Their
refractive power is not so great as that of oil, while it is much greater
than that of the spherical cells of the tubes : hence their distinct and
characteristic shadowed outline.

" These bodies (which, however, have never appeared to me to present
distinct nuclei) are probably the same with the " nucleated cells or
vesicles" described by Mr. Simon as resulting from the extravasation
of the epithelial cells into the intertubular tissue, and as progressively
enlarging, so as to form the cysts visible to the naked eye, which are so
common in diseased kidneys. To these structures he attaches great
importance in the pathology of the kidney, conceiving them to be the
invariable result of the desquamative disease when of long standing ;
the kidney being, in Mr. Simon's opinion, changed more or less into an
aggregation of microscopic cysts, which either undergo absorption and
lead to atrophy of the organ, or increase in size and monopolise its
texture. Thus, according to Mr. Simon, the serous cysts so common in
the kidney result from an enormous development and hypertrophy of
extravasated epithelium cells, which assume the character of the vesicles

470 THE SOLIDS.

he describes, and acquire the power of increase and endogenous de-
velopment.

" Whether the bodies described by me above are the same with the
vesicles of Mr. Simon, I have some difficulty in determining : but they
are the only objects I have seen which correspond at all closely with his
description ; unless, indeed, it were possible to suppose, as Dr. Johnson
appears to hint, that he may have mistaken the normal disposition of
the tubuli for a cystic structure.

" However this may be, I am satisfied that the vesicles above described
are exceptional productions, and by no means invariably connected,
as Mr. Simon describes his vesicles to be, with the progress of the
desquainative degeneration. They are seen in comparatively few cases :
on referring to four, of which I have drawings or memoranda, I find two
to have been congested and waxy kidneys, with slight exudation, one to
have been a soft and desquamating kidney, also with slight exudation,
and one a granular kidney with numerous cysts, from the size of a pea
to that of a hazel-nut. On the other hand, I have examined organs
in every stage of desquamative disease without finding these bodies, the
production of which cannot therefore be an essential step in the degener-
ation and atrophy of kidneys so affected.

" The origin and progress of these vesicles is very obscure. It is not
improbable that, as Mr. Simon asserts, they are transformed into the
larger cysts visible to the naked eye : though I confess that I have not
been able to trace the intermediate steps of their progress in a satisfac-
tory manner. On the other hand, their origin from extravasated
epithelial cells seems exceedingly improbable ; indeed I have already
stated, that I do not think the epithelium ever becomes extravasated.
Moreover, the vesicles in question have all the appearance of being
formed within the tubes, although they afterwards become separated
from them.

" From the occasional appearances of alternate distention and constric-
tion presented by the tubes when undergoing obliteration, I am induced
to believe that cysts may be formed by the occlusion and isolation of por-
tions of tube which have not yet lost their power of secretion. Whether
the vesicles in question are formed in this way, can only be determined
by close and repeated observation : and I have not been able to obtain
demonstrative evidence on this point.

" The larger cysts in the kidney present very strong evidence of being
formed in connection with the secreting membrane. In one instance I
found their inner surface to be lined at some points with tessellated
epithelium, in the form of pentagonal or hexagonal flattened cells, with
circular nuclei ; in another case there were oval nuclei without any dis-
tinct cells, and a large number of free oil-globules of considerable size.
The existence of oil in these cysts has also been observed by Dr. Johnson.
Other products of secretion are also occasionally found. On one occa-
sion I found several cysts in a kidney, otherwise healthy in appearance,

GLANDS. 471

which contained a turbid ochrey-coloured liquid, presenting under the
microscope numerous minute crystals of uric acid. Mr. Simon mentions
having found on two occasions xanthic oxyde in considerable proportion.
I have more than once observed them to contain blood in large quantity ;
and I have likewise found them full of a matter like stiff glue.

" The occurrence of cysts in kidneys presenting a generally healthy
structure is so frequent, as to lead to the idea that they must be in such
cases the result of disease which has been arrested before any consider-
able disorganisation has taken place. Many of the cases of partial
atrophy of the kidneys figured by Rayer are probably due to the rup-
ture or obliteration of these cysts.

*' Before leaving the subject of cyst-formation I may state, that in one
instance I have observed the Malpighian capsules to be occupied by
distinct cysts.*

" Dilatation and Thickening of the Tubes. — This condition, although by
no means a very frequent one, is important as being characteristic, so
far as I have observed, of the extreme stage of what I have called the
4 waxy degeneration.' I have scarcely ever seen it unaccompanied by
entire obliteration of the vessels, and by enlargement and increased
density of the kidney. The organ has the dense resistant feeling of
fibro-cartilage, and both cortical and tubular portions have the light
yellow colour, and the appearances described above as those of the
waxy degeneration in its last stage. The strke of the pyramids appear to
radiate indefinitely towards the surface, and meet the cortical substance
in digitations, instead of being marked off by a sharp semicircular line,
as occurs in the healthy kidney. When examined with a simple lens, or
even the naked eye, the pyramidal strias are seen to pursue an unusually
sinuous course : this is peculiarly the case where they pass into the cor-
tical substance. Moreover, the pyramids are unusually broad at the
bases ; and the length of the straggling digitations is sometimes so great,
that I have measured fully an inch and a half between the extreme end
of the striae and the corresponding papilla. Nevertheless, the cortical
substance is not usually diminished in quantity, being developed to a
great extent between the pyramids.

" This condition I have ascertained to proceed from dilatation and
thickening of the tubuli uriniferi throughout the organ. The dilated
tubes are usually twisted and varicose, as may be seen by inspecting a
section of the pyramids with a low power. When examined with a
higher power, the section presents an appearance very similar to some
tumours (of the fibrous or nbro-cystic kinds); viz. a number of com-
pressed areolae, enclosed by fibrous tissue, and presenting an appearance
of irregular concentric rings, of various distinctness, (an effect appa-

* Obs. In one case of cystic disease of the kidneys which fell under
the notice of Mr. Quekett, the formation of the cysts evidently commenced
in the corpora Malpighiana beneath the capillary plexus.— A. II. H.

472 THE SOLIDS.

rently due to the peculiar refraction of light by the thickened mem-
brane). The nuclei are obscured or invisible, owing to the thickness of
the intervening wall, but nevertheless exist in considerable numbers.
The Malpighian bodies and capillaries are usually obliterated. The
kidney has in fact become, like the tumours whose structure it resembles,
a true non- vascular texture.

" The explanation of the peculiar extension of the pyramidal striae
towards the surface in these cases, is to be found in the fact, that even in
the normal condition the convoluted tubuli have a general disposition
from the bases of the pyramids towards the surface, in the direction of
the striae of the cones. This is evident from the facility with which the
gland tears in that direction ; although in the normal state this dispo-
sition is masked by that of the vessels, which, passing in strait lines
through the cones, break into a complicated network of capillaries at
the bases of the pyramids. In the present lesion, the vessels having dis-
appeared, and the course of tubes being strongly marked, their disposi-
tion towards the surface becomes manifest, and the abrupt line of
demarcation between the cortical and pyramidal substance, caused by
the presence of the vessels, is obliterated."

CONCLUSION.

WITH the view of enabling the reader to place the foregoing observa-
tions in relation with the descriptions found in systematic pathological
works, Dr. Gairdner subjoins the following short remarks on the principal
physical characters usually ascribed to diseased kidneys.

" Increase of Size and Weight : Hypertrophy. — Enlargement of the
kidney occurs chiefly in consequence of three conditions : — 1st. from
sanguineous engorgement ; 2d. from distention of the tubes by secretion
or exudation ; 3d. from permanent dilatation and thickening of the tubes.
Of all these causes, the second is by far the most common. The last is
characteristic of the waxy degeneration formerly described.

" The quantity of liquid in the tubes is, at all times, subject to so much
variation, that it is difficult to say what amount of increase of weight
may be thereby occasioned without the existence of any positively morbid
condition. It is not very uncommon to find kidneys otherwise not differ-
ing from the healthy standard, about double the usual weight, or between
seven and eight ounces each. I have more than once found them to
weigh nine ounces each, with very slight marks of disease. When the
weight much exceeds this, it is probable it arises from the rare combina-
tion of vascular and tubular engorgement.

"In kidneys containing oleo-albuminous exudation, the greatest increase
of size is attained, when the exudation is universal, and unaccompanied
by desquamation.

GLANDS. 473

"Cystic degeneration of the kidneys, dilatation of the pelvis and ureters
(Hydronephrose, Rayer), &c., also give rise to great increase of size and
weight.

"Diminution of Size and Weight: Atrophy. — This condition sometimes
occurs to a certain extent, in emaciated subjects, without any disor-
ganisation, owing to the diminished activity of secretion. More fre-
quently, however, it is the result of separation of the epithelium, followed
by contraction and obliteration of the tubular structure.

" Atrophy, from this cause, is liable to supervene in all other varieties
of renal lesion, except the waxy degeneration, which appears to lead to
a permanently hypertrophied condition of the organ. In kidneys en-
larged from exudation, the occurrence of desquamation and its conse-
quences is frequent ; and the diminution of size in such cases is often
not followed by a return to the natural condition, but by permanent
atrophy.

" The course of all disorganising diseases of the kidney is to produce
first, enlargement, and then contraction of the organ. In the extreme
stages of the atrophy which results from exudation, exudation is often
nearly absent. When exudation, therefore, even in very sparing
quantity, accompanies a contracted condition of the kidney, there is a
probability that it has been abundant at some former period.

" Irregularities of Surface : Tuberculated and Granulated Kidneys. —
The smoothness of the surface in the kidney is destroyed either by un-
equal dilatation or unequal contraction of the tubuli of the cortical
substance. The former takes place in the waxy degeneration ; the latter,
in the desquamative processes.

" The most frequent irregularities of surface are formed in connection
with the granulations of Bright. These are invariably formed when
exudation is deposited in kidneys tending to the desquamative lesion ;
and, as this runs its usual course, the granulations become prominent
from the destruction of the tubes around them. An extreme degree of
the irregularities thus produced constitutes the tuberculated kidney.

" The puckering and partial atrophy occasionally seen in kidneys, other-
wise not morbid, or comparatively slightly diseased, are probably, in
many instances, the result of the obliteration of cysts.

" The more remarkable changes in colour and consistence are described
very fully in many parts of the preceding memoir."

On reviewing the whole of the preceding observations, Dr. Gairdner is
induced to regard the following conclusions as especially important in
relation to the pathology of renal diseases : —

"1. By far the greater part of the pathological lesions of the kidney
arise from, or are connected with, the exudation of oleo-albuminous
granules into the interior of the tubes and epithelial cells.

" 2. The oleo-albuminous exudation is, probably, often preceded, and,
certainly, occasionally accompanied, by vascular congestion ; but when
the quantity of exudation is considerable, more or less complete depletion

474 THE SOLIDS.

of the vascular system invariably occurs. This is a secondary result of
the obstruction of the tubuli uriniferi.

" 3. The oleo-albuminous exudation occurs in two chief forms : viz.
first, universal infiltration of the tubes throughout the organ ; and, second
infiltration of peculiar sets of tubules : the rest remaining free, or nearly
so. In the latter mode arise the granulations of Bright.

"4. There is no essential anatomical difference between the exuda-
tions in the kidney, which are the result of chronic processes, and those
which have been considered as the result of inflammation.

"5. The capillary vessels of the kidney are subject to spontaneous
obliteration (unaccompanied, in the first instance, by any visible lesion of
the tubes), giving rise to the peculiar affection which I have called the
waxy degeneration. This obliteration of the vessels is probably, in all
cases, preceded by a stage of congestion.

" 6. The consequence of the waxy degeneration is thickening and
varicose dilatation of the tubuli throughout the organ.

".7. The tubes of the kidney are subject to contraction and oblitera-
tion, in consequence of the desquamation of their epithelium ; a condition
resulting in atrophy, and complete disorganisation of the organ.

" 8. The desquamation of the epithelium occurs very frequently in all
the other diseased conditions of the kidney. When sufficiently long-
continued and extensive, it produces contraction, and this indifferently,
whether exudation be present or not. It is sometimes accompanied by
vascular congestion in every stage of its progress.

" 9. The earlier stages of the exudations can only be discovered by
means of the microscope. The progress of the waxy degeneration, on
the contrary, is best traced by the unaided eye. The desquamation of
the epithelium is only to be discovered with certainty by means of the
microscope, and is particularly apt to escape attention, under all circum-
stances, if the kidney only, and not the urine, be looked to. It results
that careful investigation, both by the microscope and the naked eye,
both of the kidney after death and the urine during life, are indispens-
able, to enable the pathologist to determine with exactitude the presence
or absence of disease."

I have been induced to dwell thus largely on the micro-
scopic pathology of the kidney : first, on account of the great
importance and interest attached to the lesions of that organ ;
secondly, from the great number of interesting facts which the
microscope has already brought to light in reference to its
pathology ; and, thirdly, in the hope of inducing other ob-
servers to follow out more completely the enquiry which has
already led to such successful and striking results.

GLANDS. 475

TESTIS.

The testis, the last of the tubular glands in the human
subject, agrees more closely in structure with the sudoriferous
and ceruminous glands than with the kidney ; there being this
in common between the three first- mentioned, viz., that the
tubes, of which they are principally constituted, are convo-
luted, and are not enclosed in a dense framework of fibro-
elastic tissue, as is the case with those of the kidney.

The testis is invested by a tunic of white fibrous tissue ;
this sends down, into the substance of the gland, nume-
rous dissepiments, which divide the tubes of which it is
composed into parcels, each of which may be called a lobe.

The tubes of the testes are remarkable for their large size,
great tortuosity, and exceeding and ready extensibility.
(See Plate LX. figs. 1. 4.)

When viewed as opaque objects, the tubes appear of a
delicate and semi-transparent whiteness ; and, when seen by
transmitted light, they are almost black ; this arises from
the fact of the interception of the luminous rays by the cells
contained within the tubes.

The membrane of the tubes is totally distinct from that of
most other tubular glands ; it is very thick and fibrous, being
constituted of a well-marked form of nucleated fibro-elastic
tissue. (See Plate LX.y^. 4.)

The constitution of the tubes of elastic tissue explains satis-
factorily their ready extensibility and variable diameter ;
this variation, in specimens prepared for microscopic examin-
ation, is very obvious, and arises from the displacement of
contained cells, occasioned by unequal external pressure ;
where these cells are accumulated in the greatest number,
there the tubes are thickest ; and where there are but few
cells, or even where the tubes are destitute of cells, they are
thinnqst, and frequently even entirely collapsed.

These facts show that the tubes are highly expansive ; and
there is no doubt that their diameter varies, during life, in
accordance with the amount of seminal fluid contained within

Q Q

476 THE SOLIDS.

the testis ; this expansive property being especially designed
to allow of the accumulation of that fluid within the semeni-
ferous organ.

The tubes of the testis contain a vast number of granular
cells of various sizes (see Plate LX. jig. 4.), some being
several times larger than others, especially in the testis of
the adult. Most of these cells contain but a single nucleus ;
in others, however, and these the larger cells, there are as
many as from two to seven, or even more, distinct nuclei.
(See Plate X VI. jig. 1.)

In the testes of a child, the granular cells present great
uniformity of size, and contain, for the most part, but a
single nucleus. These cells, as in other tubular glands, form
a regular epithelium on the walls of the tubes, the central
channel being free ; this arrangement is very evident in the
tubes of immature testes ; but far less so in those of the
adult organ ; the manipulation to which the latter are subject,
when being prepared for microscopical observation, readily
displacing the cells.

It is in these cells, according to the observations of nu-
merous observers, that the spermatozoa are developed. For
further particulars on the development of the spermatic
animalcules, see the article " Semen."

The tubes of the testes are loosely bound together by
bands of fibrous tissue ; it is this tissue which contains the
tortuous blood-vessels with which this organ is so copiously
supplied.

That the tubes are not furnished with a distinct external
envelope, like those belonging to the kidney, is proved
by the fact that they admit readily of being separated from
each other, as also of being drawn out to a great length : this
last circumstance shows the extent to which the tubes are
convoluted, the few anastomoses which take place between
them, and their extraordinary elasticity.

GLANDS. 477

VASCULAR GLANDS.

The vascular glands all agree with each other in the absence
of excretory ducts or channels for the discharge of their
secretion, a deficiency which involves as a necessary conse-
quence the reception of the secreted fluids by the blood-
vessels.

From the differences in the size and structure of these
several glands, it is very doubtful whether any other resem-
blance besides that just pointed out exist between them, and
it is most probable that each has a separate purpose to fulfil
in the animal economy.

THYMUS.

The thymus, although usually spoken of and described as a
single organ, is in reality double, and consists of two distinct
glands united to each other in the middle line by cellular
tissue only.

Each separate adult thymus is constituted of numerous,
probably some hundred follicles, which vary in size from a
pin's head to, in some cases, that of a pea, and the wralls of
which are made up of mixed fibrous tissue.

These follicles are usually more or less rounded, but some-
times polygonal in shape from pressure ; they are loosely held
together by fibrous tissue, and by the blood-vessels which
supply them ; they each contain in their interior a cavity
which is more or less filled with a milky fluid. (See Plate LXI.
Jig. 8.)

Several of these follicles open into each other and into a
common receptacle or " pouch," and this last again opens into
the internal cavity of the gland, the face of which is thickly
studded with similar openings.

On its exterior each follicle may be seen, even without
injection, to be invested with a very beautiful plexus of blood-
vessels, represented in Plate LXI. fig. 8.

QQ 2

478 THE SOLIDS.

When unravelled by the removal of the interlobular cellular
tissue, the whole gland is seen to consist of a straight tube,
with the follicles arranged around it in a spiral manner.

The central cavity, " reservoir of thymus," is lined by a
delicate mucous membrane, which is raised into ridges by a
layer of ligamentous bands situate beneath it ; these proceed
in various directions, an'd encircle the apertures of the pouches :
their use is to keep the lobules together, and to prevent the
injurious distention of the cavity.

The whole organ is enclosed in a dense capsule of fibrous
tissue, the blood-vessels contained in which are remarkable
for their disposition in threes, an arrangement which is not
uncommon in the capsular investments of glands. (See
Plate LXI. fig. 7.)

The " milky fluid " contained in the follicles and reservoir
is made up, to a great extent, of an immense number of
granular nuclei, as well as numerous cells of large size, which
do not appear hitherto to have been either described or figured
in a satisfactory manner, and which are probably to be re-
garded in the light of parent cells. (See Plate LXI.
fig. 10.)

Many of these cells contain several granular nuclei, each of
which is surrounded by one or more concentric lamellae ; they
thus resemble the cartilage cells found in the intervertebral
substance, and also certain species of Microcystis, a genus of
Freshwater Algae.

Mr. Simon, in his " Prize Essay," makes the following
observations on the above-described cells : — " In specimens
taken from animals past that period of life when the thymus
is most active, I have found cells in which these dotted cor-
puscles occupied the relation of nuclei. The cells are at first
little larger than the corpuscles themselves, and contain a
perfectly pellucid material ; but as they grow, their contents
become molecular, and they develope themselves into perfect
fat cells, which lie in the cavities of the glands, and in some
instances completely fill them. During the period in which
these cells are being developed, the application of acetic acid
to the preparation as it lies under the microscope shows

GLANDS. 479

them to have great affinity to embryonic cells ; for the acid
dissolves the cell-membrane completely away, and leaves
the nucleus of the cell (the dotted corpuscle) unaffected by its
action."

Lining each follicle, Mr. Simon has detected a delicate and
homogeneous structure, which he has termed the " limitary
membrane : " this structure is identical with the basement
membrane of Bowman, and is probably common to all glands,
especially the follicular ones.

Mr. Simon has likewise described a lobular arrangement
of the follicles. The structure of the gland resolves itself, he
says, " into masses ranged round an axis. Each mass con-
stitutes a sort of cone of glandular substance, its apex pointing
to the axis or mesial line of the gland ; its base directed to
the surface, where it presents innumerable vesicles ; while
its intermediate part contains those successive branchings of
the follicle which terminate superficially in the vesicular
form."

THYROID GLAND.

The anatomy of this gland is best studied in a specimen
which has undergone a slight enlargement of its several parts :
a portion of such a gland, when viewed with the inch object-
glass, bears so close are semblance to a mass of fat, that, except
by a practised microscopist, it would be impossible to dis-
tinguish it therefrom with such a low power ; even when
viewed with the half-inch, the illusion would scarcely be dis-
pelled, and it is only on the application of the quarter-inch
glass, that misgivings would begin to be entertained in re-
ference to its identity with fat.

The resemblance borne by a portion of thyroid gland thus
slightly enlarged by disease to a mass of fat, arises from the
form of the vesicles or closed cells of which the gland is com-
posed, and from the manner in which they reflect the light,
the centre of each vesicle being clear and bright, and the cir-
cumference dark and almost black; here, however, the re-

QQ 3

480 THE SOLIDS.

semblance ceases, as the thyroid vesicles are most satisfac-
torily distinguished from fat globules by their larger size,
the fibrous texture of their parieties, and the nature of their
contents.

Such is the general character and appearance of a portion
of thyroid examined microscopically ; the entire gland, how-
ever, consists of two lobes, which are placed one on each side
of the trachea, and which are connected with each other by a
narrow slip or isthmus of the gland, and these lobes are
further divisible into numerous lobules, many hundreds to
each lobe. Now it is these lobules which, so far as the
descriptions hitherto given of this gland are to be under-
stood, have been regarded and described as the mem-
branous cavities of the thyroid (see Plate LXI. fig. 1.),
the true and ultimate cellular structure being in general
overlooked.

Thus the lobules are further divisible, each into many small
cavities, the ultimate divisions of which the gland is suscep-
tible. (See Plate LXI. figs. 2, 3, 4, 5.) These in the slightly
enlarged gland are circular, and comparable to fat vesicles
(see Plate LXI. figs. 2, 3.) ; but in the gland in its normal
state, they are compressed and angular, being also very liable
to be altogether overlooked, their size and form being indicated
only by certain light-coloured spaces traversing the lobule.
(See Plate LXI. fig. 6.)

Over the surface of each lobule, the blood-vessels form a
plexus, from which branches proceed inwards, encircling the
vesicles much in the same way as the blood-vessels do the
fat corpuscles. (See Plate LXI.jft/. 1.)

The cavity of each vesicle is perfectly distinct, and does
not communicate with that of any other of the vesicles by
which it is surrounded : the fibrous tissue, however, of which
its walls are so evidently composed (see Plate LXI. fig. 4.)
does communicate with and run into that of the neighbouring
vesicles, at certain points, however, only. These fibres may
frequently be traced from the wall of one cell into that of
another ; and it is this fibrous union of the vesicles which
renders it impossible completely to isolate any one of the

GLANDS. 481

cells, and accounts for the fact, that when the vesicles are
broken up with needles, they are entirely reduced to fibrous
tissue.

The contents of the vesicles consist of a fluid, containing
numerous granular nuclei of a rounded or oval form, as well
as of a few perfect cells, two or three times larger than the
nuclei, and the granules contained in which are very large,
presenting an oily aspect; between these two extremes of
size, other cells intermediate are met with : the larger are evi-
dently parent cells. (See Plate LXL figs. 9. and 4.)

The fluid of the vesicles contains a good deal of oil, which
when the gland is slightly decomposed, is apt to collect in
them in the form of one or two large circular discs.

The increase in the size of the gland in goitre is due to
an increased development of the vesicles and of their con-
tents.

It is evident that each vesicle contains all the elements of
the gland, and that the entire organ is made up of an assem-
blage of many thousands of such vesicles or glands. (See
Plate LXL fig. 2.)

SUPRA-RENAL CAPSULES.

The supra- renal capsule bears some resemblance in structure
to the kidney, being divisible like it into a cortical and medul-
lary substance.

It is made up of numerous simple and cylindrical tubes
closed at both ends, and formed of structureless basement
membrane ; these tubes are disposed in a vertical manner, one
extremity forming the surface of the organ, and the other
extending in an opposite direction, as far as the inner cavities
or Iacuna3 situated in the centre of each supra-renal capsule.
(See Plate LXII. fig. 3 a.)

These tubes enclose elements of three kinds ; first, innu-
merable circular particles or molecules, which reflect the light
strongly, and which are of an oily nature ; of these the greater
part is free in the tubes, but a lesser proportion is en-

Q Q 4

482 THE SOLIDS.

closed in certain of the cells which are met with in the
tubes ; second, granular nuclei in large quantities ; and, third,
parent cells of considerable size, containing each several
nuclei intermingled with, and in part very frequently ob-
scured by a considerable number of the bright molecules
previously referred to. These parent cells do not appear to
have been hitherto characterised with any degree of precision.
(See Plate LXII. fig. 3 b.)

The differences between the cortical and medullary portions
of the supra-renal capsule, depend principally upon the irre-
gular disposition of the tubes in the latter, the plexiform
arrangement of the vessels, and on the presence of numerous
parent cells containing more or less of colouring matter in
their interior. It is these cells which impart to sections
of the gland the dotted appearance so commonly observed in
its medullary portion. (See Plate LXII. fig. 3.)

The vascular distribution in the supra-renal is very simple.
On the surface of the organ we have a very beautiful plexus
of capillaries, the pentagonal and hexagonal meshes of which
lie in the intervals between the extremities of the tubes ; in
the tubular part the vessels, both veins and arteries run in
straight lines between the tubules, terminating, on the one
hand, in the plexus on the surface, and, on the other, in the
central plexus. (See Plate LXII. fig. 1. 5.)

The supra-renal is an organ which varies greatly in dif-
ferent subjects ; in some the proportion of granules is much
greater than in others ; in others again, the central lacunas
are occupied with a whitish-looking substance, which, on
examination, is found to consist of granular nuclei arranged
in irregular masses, but in which sometimes we can detect a
tubular disposition : in these cases we encounter from without
inwards, three substances ; cortical, medullary, and then lastly,
the central substance just described.

The capsule of the supra-renal is often laden with fat,
which totally obscures the plexus on the surface of the
organ.

The parent cells, when filled with oily molecules, bear a
close resemblance to the cells of a sebaceous gland, between

GLANDS. 483

which and the supra-renal capsule one would hence be dis-
posed to suspect a degree of affinity.

SPLEEN.

The spleen consists of a fibro- elastic capsule which sends
down from its inner surface septa, which penetrate the
organ in all directions, and divide it into compartments ; of
an immense assemblage of blood-vessels which compose its
chief substance, and which impart to it the character and ap-
pearance of an erectile tissue ; and, thirdly and lastly, of a
small quantity of secreting structure, consisting of nuclei
only, and which appears to lie in the intervals between the
blood-vessels. (See Plate LXII. fig. 2.)

The above comprehends all that can be readily made out
of structure in the " spleen : the examination, however, of
this organ is by no means satisfactory or easy on account of
the impossibility of fully injecting it, a difficulty which arises
from causes but imperfectly understood.

Dr. Julian Evans, however, describes a very elaborate
structure and arrangement of the tissues in the spleen, as will
be seen from the perusal of the following abstract of his paper
taken from the 3d edition of Carpenter's " Principles of
Human Physiology."

" According to the account of Dr. Julian Evans *, whose
researches appear to have been more successful than those
of any other anatomist, the spleen essentially consists of a
fibrous membrane, which constitutes its exterior envelope,
and which sends prolongations in all directions across its
interior, so as to divide it into a number of minute cavities or
lacuna? of irregular form. These splenic lacunce communicate
freely with each other, and with the splenic vein ; and they
are lined by a continuation of the lining membrane of the
latter, which is so reflected upon itself, as to leave oval or
circular foramina by which each lacuna opens into others, or

* Lancet, April 6th, 1844.

484 THE SOLIDS.

into the splenic vein. The lacunae, whose usual diameter is
estimated by Dr. E. at from half to one third of a line, are
generally traversed by filaments of elastic tissue, imbedded in
which a small artery and vein may be frequently observed ;
over these filaments, the lining membrane is reflected in folds ;
and, in this manner, each lacuna is incompletely divided into
two or more smaller compartments. There is no direct com-
munication between the splenic artery and the interior of the
lacunas ; but its branches are distributed through the inter-
cellular parenchyma (which will be presently described) : and
the small veins which collect the blood from the capillaries of
the organ, cqnvey it into these cavities, from which it is
conveyed away by the splenic vein. The lacunae may be
readily injected from the splenic vein with either air or liquid,
provided they are not filled with coagulated blood ; and they
are so distensible, that the organ may be made to dilate to
many times its original size with very little force. This is
especially the case in the spleen of the Herbivora ; for the
spleen of a sheep weighing four ounces, may be easily made
to contain thirty ounces of water. That of man, however, is
less capable of this kind of enlargement. According to Dr.
Evans, the lacunae of the spleen never contain any thing but
blood ; and he notices that a frequent condition of the human
spleen after death, which is sometimes described as a morbid
appearance, consists in the filling of the lacunae with firmly
coagulated blood, which gives a granular appearance to the
organ.

" The partitions between the lacunae are formed, not only
by the membranes already mentioned, but by the peculiar
parenchyma of the spleen ; which constitutes a larger part of
the organ in man, than in the Herbivorous Mammalia. It
presents a half-fluid appearance to the eye ; but when an
attempt is made to tear it, considerable resistance is expe-
rienced, in consequence of its being intersected by what ap-
pear to be minute fibres. When a small portion of it is
pressed, a liquid is separated ; which is that commonly known
as the Liquor Lienis, or splenic blood ; which is usually de-
scribed (but erroneously, according to Dr. E.) as filling the

GLANDS. 485

lacunae of the spleen. This liquid, when diluted with serum
and examined under the microscope, is found to contain two
kinds of corpuscles, — • one sort being apparently identical
with ordinary blood-corpuscles, — and the other with the
globules characteristic of the lymph and abundant in the
lymphatic glands. The remaining fibrous substance consists
entirely of capillary blood-vessels and lymphatics, with minute
corpuscles, much smaller than blood-corpuscles, varying in
size from about l-6000th to 1 -7000th of an inch, of spherical
form, and usually corrugated on the surface. These lie in
great numbers in the meshes of the sanguiferous capillaries ;
and the minute lymphatics are described by Dr. E. as con-
nected with the splenic corpuscles, and apparently arising
from them. Lying in the midst of the parenchyma, are
found a large number of bodies, of about a third of a line in
diameter, which are evidently in close connection with the
vascular system ; these have been long known as the Mal-
pighian bodies of the spleen, after the name of their dis-
coverer ; but since his time, their existence has been denied,
or other appearances have been mistaken for them.

" According to Dr. E., they in all respects resemble the
mesenteric, or lymphatic glands in miniature, consisting as
they do of convoluted masses of blood-vessels and lymphatics,
united together by elastic tissue, so as to possess considerable
firmness : and they further correspond with them in this —
that the lymph they contain, which was quite transparent in
their afferent lymphatics, now becomes somewhat milky,
from containing a large number of lymph globules."

Dr. Hanfield Jones has noticed the occurrence of certain
peculiar corpuscles in the spleen of various animals, including
that of fishes, mammals, and man; these corpuscles he de-
scribes as follows * : —

" In the spleens of various animals there may often be seen
ii number of minute corpuscles of a yellow colour, varying
from' a dark to a pale hue ; they occur sometimes singly, but
mostly in groups, which I have sometimes thought were

* Medical Gazette, 1847, p. 141.

486 THE SOLIDS.

aggregated, especially along the larger blood canals. These
groups are made up of corpuscles of very various size ; they
do not appear to have any special connexion with the sur-
rounding substance, which occasionally, however, has a de-
cided yellow tinge.

" In the animal series, I have found these corpuscles most
highly developed in fishes. In the human subject they are
rarely to be found. I have, however, observed them distinctly
in six instances, in one of which they were very large and
numerous. In most of the cases in which they were found
there had been considerable interruption to the respiratory
process. The spleen was generally much enlarged, soft, and
of rather a pale colour, quite an opposite condition to that
often observed in cases of f Bright's disease,' where the
organ is found small and contracted : in such spleens I have
never found any of the yellow corpuscles."

For a description of the Pineal and Pituitary glands,
placed in the classification under the heading " Vascular
Glands," the reader is referred to the Appendix.

ABSORBENT GLANDS.

The absorbent system of vessels is divisible into lacteals
and lymphatics, the glands attached to the former being
called mesenteric, and those to the latter, lymphatic glands.

The lacteal absorbents commence in a plexiform manner in
the villi of the small intestines, while the lymphatic absorbents
originate all over the body, in the same manner, in each of the
several tissues and organs of which it is composed : they are
minute, delicate, and transparent vessels, remarkable for their
uniformity of size, a knotted appearance due to the presence
of numerous valves, the dichotomous divisions which occur
in their course, and their separation into several branches im-
mediately before entering a gland.*

* See the Article " Lymphatic System," by Mr. Lane, in the Cyclo-
paedia of Anatomy and Physiology.

GLANDS. 487

In the mesentery, the lacteals become variously coiled and
knotted, these aggregations of coils, together with fibrous
tissue and blood-vessels, forming the mesenteric glands ; the
lymphatic glands have a similar structure and origin, being
placed in certain determinate regions of the human body.

The lymphatics which enter a gland, or the afferent lym-
phatics, vary in number from two to six ; they divide at a
short distance from the gland into several smaller vessels,
and enter it by one of the flattened surfaces: while those which
leave it, or the efferent lymphatics, escape from the gland on
the opposite, but not unfrequently on the same surface ; they
also consist, at their junction with the gland, of several small
vessels, which unite after a course of a few lines and form
from one to three trunks, often twice as large as the afferent
lymphatics.

The afferent lacteals and lymphatics, as they enter the
gland, become somewhat dilated ; and the epithelium, in place
of forming a single layer of flattened cells firmly adherent to
the walls of the tubes, consists of several layers of rounded
and glandular cells, which are very readily displaced.

These cells are doubtless more or less concerned in the
elaboration of the fibrin of the chyle ; and there is much
reason to believe that from time to time the more mature
cells become detached from the walls of the lacteals, and are
conveyed along with the chyle into the blood, where they
become the white or granular corpuscles of that fluid.

Such is a very brief outline of the minute anatomy of the
mesenteric and lymphatic glands.

This is probably the most fit place to introduce a few re-
marks on the structure of the villi themselves, the chief agents
in the absorption of the chyme, and the parts in which the
lacteals themselves take their origin.

The Villi of the Intestines.

The villi exist in the whole extent of the small intestines,
but it is in the lower part of the duodenum and the whole

488 THE SOLIDS.

of the jejunum that they are best developed, and the lacteals
most readily detected.

Several distinct structures have to be noticed and described
entering into the constitution of each villus : these are the
epithelium resting upon the outer surface of the villus, the
basement membrane, the intra-villous nuclear contents, the
fatty intra-villous contents, the blood-vessels of the villus
and its lacteals ; these several parts will be described in the
order of their enumeration. •

The epithelium investing the villi (see Plate LIT. Jig. 1.),
is of the conoidal variety already fully described and figured.
It not merely clothes the villi from base to summit ; but
also the interspaces between them, as well as the numerous
follicles of Lieberkuhn, situated in the whole length of the
small intestines.

According to the observations of Professor Goodsir, this
epithelium is shed on each recurrence of the process of
chymefication, the cells first absorbing the partially elabor-
ated chyme, effecting a further elaboration of it, and finally
becoming ruptured and dissolved, set free the fluid absorbed,
at the same time adding their own substance to augment its
amount and nutritive qualities.

The accuracy of this view is in the main admitted by
most observers ; Professor Weber and Dr. Jones, however,
do not consider that the shedding of the epithelium is neces-
sary to enable the villi to perform their function ; and the
latter observer makes the following remarks on this point :
" I have certainly seen the villi clad with their epithelium
when the lacteals have seemed to be every where filled
with chyle : however, I think there can be little doubt that,
when the absorbing process is most actively performed, the
villus does throw off its protecting covering ; certainly, this
is the case in a great number of instances."

The basement membrane of the villi is a continuation of
that of the general surface of the mucous membrane, and is,
as far as has yet been ascertained, perfectly structureless.

* Medical Gazette, Nov. 17th, 1848.

GLANDS. 489

The granular, or, more correctly speaking, the nuclear,
contents of the villi have been noticed by several observers
(See Plate LII. fig. 1,2.). Dr. Jones, however, in the com-
munication already referred to, has pointed out the fact that
the nuclear and granular contents of one villus are con-
tinuous with those of another, and that the granules and
nuclei form a continuous stratum lying beneath the base-
ment membrane, extending not merely from villus to villus,
but also throughout the large intestines, where it is very
easily seen in the spaces between the follicles.

Professor Goodsir has described these granular nuclei, as
enlarging during the process of absorption, and as forming
a number of enlarged and very evident cells at the apex of
the villus. These supposed cells, however, are nothing
more than oil drops, usually of a brown colour, and of
various sizes. (See Plate LII. fig. 2.) At this conclusion I
arrived many months since, and gave a figure of these oil
drops in the villi in the 13th Part of the Microscopic
Anatomy, published in April 1848 ; and I am glad that
Dr. Jones entertains a similar opinion of their nature. I
may at the same time remark, that the cells delineated in
the original figure given by Professor Goodsir, have all the
characters of oil drops, being round, smooth, and reflecting
the light strongly.

The use of these oil drops in the villi is by no means
evident : they are formed, in all probability, by the cohesion
of the smaller oily granules which are scattered throughout
the villi during the process of absorption, and which con-
tribute so greatly to their opacity ; in the end they are most
probably absorbed by the lacteals.

Notwithstanding, however, the non-existence of the pecu-
liar cells described by Professor Goodsir, the leading idea of
that observer of the elaboration of the chyme within the
villus is still correct, the agents in this Avork being the
nuclei already described.

The presence of these nuclei throughout the whole length
of the villus seems to point to the inference that it is not
the apex only which absorbs.

490 THE SOLIDS.

Each villus is copiously supplied with blood-vessels ; an
artery ascends one side of the villus, a vein descends along
the opposite side, and between these two principal vessels a
very complicated and beautiful plexus of capillaries is ex-
tended. (See Plate LI. Jigs. 3, 4, 5.).

The lacteals are described as originating in the villi in a
plexiform manner.

In the rabbit I have observed a very curious construction
of the villi, their surfaces being studded with numerous
mucous follicles; the portion of intestine exhibiting these
characters was most probably taken from near the junction
of the large and small intestines; and I have little doubt
but that the villi of the human intestine, in a corresponding
position, would exhibit the same combination of the structural
peculiarities of both small and large intestines.

The anatomical characters of the mucous membrane of
the stomach, and large intestines, have already been de-
scribed. (See page 393. et seg.)

ORGANS OF THE SENSES. 491

ART. XXII. ORGANS OF THE SENSES.

TOUCH.
Papillary Structure of the Skin.

THE sense of Touch is the simplest as well as the most
universally diffused of the senses, it not merely extending
over every portion of the external surface of the body, but
also over certain of the internal mucous surfaces, as those of
part of the mouth, nose, &c.

Over the general surface of the body this sense exists
under the form of common sensation ; and it is only in
certain parts, as on the palmar and plantar surfaces of the
hands and feet, that it becomes so highly developed as to
assume the importance of a distinct sense, and to deserve
the name of Touch.

This sense has its seat in the papillary structure of the
skin, and the degree of the development of this structure,
as shown by the size and number of the papilla?, is always
proportionate to the degree of perfection of the sense : thus
the papillae over the general surface of the body are much
less numerous and less perfect in form than they are in the
palms of the hands and soles of the feet.

The papilla? in the natural state are of course invested by
the epidermis, which indeed conceals them to a great extent
from view ; this requires to be removed by maceration be-
fore their form, size, and arrangement can be clearly as-
certained.

After the removal of the epidermis, it will be seen that
the papilla? on the general surfaces of the body do not follow
any definite arrangement, but are scattered here and there
without apparent order, more or less thickly according to
the degree in which the part of the integument upon
which they are seated is endowed with sensation, but every

R R

492 THE SOLIDS.

where they are less numerous than on the palmar and plantar
surfaces of the hands and feet, (See Plate LXIII. Jig. 4.)

On the palms of the hands and soles of the feet, the
papillae are arranged, as may be seen with the naked eye, in
lines or ridges, each ridge being made up of two rows of
papillae in single file, and between each pair of which a further
line of separation may be traced : such is the general dispo-
sition of the papillae in each ridge ; the ducts of the sudori-
ferous glands pass through its centre, and between the
rows of papillae, the number of these glands and ducts to
that of the papilla being in the proportion of one to four.
( See Plate LXIII. Jig. 3.)

The arrangement just described can be well seen on the
palms of the hands by the aid of a lens, even while the
epidermis is still attached to the cutis ; the ridges are seen
to be disposed here and there in beautiful curves, some
abruptly coming to a termination, and others dividing into
two distinct ridges, this disposition enabling them to adapt
themselves more accurately to the varying nature of the
surface over which they are extended : along the middle of
each ridge, the apertures of the numerous sudoriferous glands
may be seen for the most part crossed in the direction of
the diameter of the ridge by a faint groove, which indicates
the line of separation of the papillae into pairs. (See
Plate LXIII. fg. 1.)

Each papilla appears to consist of a prolongation of base-
ment membrane, and contains in its interior granular and
nuclear contents and a single looped blood-vessel, (see
Plate LXIII. Jigs. 3. 7.) : these points of structure are all
made out readily enough ; the chief difficulty consists in the
determination of the manner in which the nerve filaments,
with which the papillae are undoubtedly supplied, terminate
in them. On this subject, Messrs. Todd and Bowman*
have the following observations: — "In regard to the pre-
sence of nerves in the papillae themselves, we can affirm
that we have distinctly traced solitary tubules ascending

* Physiological Anatomy, p> 412.

ORGANS OF THE SENSES. 493

among the other tissues of the papilla about half way to
their summits, but then becoming lost to sight, either by
simply ending, or else by losing the white substance of
Schwann, which alone enables us to distinguish them in
such situations from other textures. Thin vertical sections of
perfectly fresh specimens are essential for this investigation,
and the observer should try upon them the several effects of
acetic acid and solution of potass. In thus describing the
nerves of the papilla? from our own observations, we do not
deny the existence of true loop-like terminations as figured
by so respectable an authority as Gerber ; but neither do we
feel entitled to assent to it. ... We incline to the belief
that the tubules, either entirely or in a great measure, lose
the white substance when within the papillae."

Messrs. Todd and Bowman further observe, in reference
to the structure of the papilla? : — " Within the basement
membrane it is difficult to distinguish any special tissue,
except by artificial modes of preparation. A fibrous struc-
ture, however, is apparent, having a more or less vertical
arrangement; and with the help of solution of potass, fila-
ments of extreme delicacy, which seem to be of the elastic
kind, are generally discoverable in it."

The blood-vessels of the papilla? consist of single loops ;
each of these is made up of an artery and a vein : the former,
derived from the arterial plexus of the cutis, ascends the
papilla on one side, and on reaching its summit gradually
merges into the vein which descends along its opposite side,
and terminates in the venous plexus of the cutis. In an
injected preparation, and where the villi are large, the turn
of the loop is seen to be very abrupt, the two vessels, the
artery and the vein, coiling round each other, and resembling
a piece of twine which has been bent upon itself and afterwards
twisted in a spiral manner. This disposition of the vessels
seems intended to delay somewhat the passage of the blood
through the papillae. (See Plate LXIILjfy. 7.)

The thickness of the epidermis which so closely invests
the papillae, does not appear to have any direct relation to
the sense of touch: thus, over the general surface of the body,

R R 2

494 THE SOLIDS.

where this sense exists only as common sensation, the
epidermis is very thin, while over the palmar surface of the
hands it is very thick ; the epidermis must not be too thick,
however, even in this situation, as is shown by the fact, that
where it has been greatly thickened by manual labour,
touch is totally obscured.

The density of the epidermis in certain situations is
evidently due to pressure, and may be explained by the fact
that such pressure induces an increased determination of
blood to the part, which is followed by increased nutrition
and development. Between the sense of touch and the
number of sudoriferous glands, there would appear to be a
certain relation : thus on the palmar aspect of the hands,
where this sense exists in its highest perfection, the number
of sweat glands is very great.

The use of these glands in this situation in such increased
numbers, may readily be conceived to be to keep the epidermis
in a moist and flexible condition, whereby impressions would
be more readily conveyed to the papillae and more distinctly
felt, the acuteness of the entire sense being thus greatly aug-
mented.

The epidermis is very accurately adapted to the papillae,
so that when detached and viewed upon its under surface,
it is seen to contain exact impressions of each and all of
them ; it is in this manner that their form, size, number,
and arrangement are best studied, and it will then be noticed
that, in all these particulars, considerable variations exist.

(See Plate LXIII. figs. 5, 6.)

•

TASTE.
Papillary Structure of the Mucous Membrane of the Tongue.

The mucous membrane of the tongue, the principal if not
the sole seat of the sense of taste, is divisible, like the skin,
into a chorion, a papillary structure, and an epidermis or epi-
thelium.

The chorion is a firm and tough membrane, formed of
mixed fibrous tissue, and containing in its substance the

ORGANS OF THE SENSES. 495

blood-vessels and nerves, arranged in a plexiform manner,
from which the papilla? are supplied: to its under surface
the extremities of the muscular fibres of the muscles of the
tongue are firmly attached ; this arrangement imparts to the
whole organ a considerable power of movement and of nice
adaptation.

The papillary structure, which is the real seat of the sense
of taste, is constituted of an immense number of papillae,
which occasion a somewhat flocculent appearance of the whole
surface of the tongue.

The papilla? are divisible into simple and compound, and
the latter again into filiform, fungiform, and calyciform ; be-
sides these several compound forms, however, others exist of
no very definite shape, but approaching more or less closely
in their characters to either the fungiform or calyciform
papillae.

The simple papillae exist principally on the sides and under
surface of the tongue, but also, though more sparingly, on its
upper surface, as between the filiform papillae, in the space
around the base of each fungiform papilla, and for a short
distance behind the calyciform papilla?, and to either side of
them. (See Plate LXV. fig. 10.)

They vary somewhat in size, form, and structure in dif-
ferent situations ; in general they are much pointed at their
extremities : behind the calyciform papilla? they are obtuse
and pyriform in shape, (see Plate LXV.^^. 11.) while on
the under surface of the tongue their extremities are very
frequently perforated, and they appear to serve the double
purpose of a papilla and mucous follicle. (See Plate LXV.

fg- 2.)

They each consist of, in addition to their epithelial invest-
ment, a layer of basement membrane, a single looped blood-
vessel, filaments of nerves, and granular and nuclear contents.
(See Plate LXV. fig. 6. and Plate LXVI. fig. 5.)

The compound papilla? are confined to the upper surface
and edges of the tongue, and do not extend, except for a
short distance at the sides, over the space bounded in front
by the calyciform papillae, and behind by the epiglottis.

R R 3

496 THE SOLIDS.

This chain of papillae forms the extreme boundary of the
space over which the sense of taste extends, the surface be-
hind it being smooth, non-papillary, and exhibiting numerous
openings of mucous glands ; thus then it would appear we
have a true gustatory region.

Each compound papilla is made up of numerous simple
papillae, arranged differently in the case of the three forms
of these already enumerated.

The filiform papillae are by far the most numerous, being
more than in the proportion of twenty to one ; when freed
from epithelium they are seen to be more or less cylindrical
in form, and to consist of a variable number of simple pa-
pillae from sixteen to twenty or more to each, arranged in a
single circular series, forming the top and margin of the
cylinder. (See Plate LXIV./#. 3.) The sides of the simple
papillae are more or less united together, but the tips are free
and pointed, some more so than others.

The length of the cylinder which each filiform papilla
describes, the degree of acumination of the apices of the
secondary papillae, and the extent of these which is free,
varies in accordance with the position of the papillae on the
tongue.

The circular disposition referred to is best seen in the pa-
pillae placed near the tip and sides of the tongue, for in those
situations the secondary papillae are short, blunt, and nearly
of equal lengths. (See Plate LXIV. Jig. 3.) In the centre
of the organ the simple or secondary papillae are much longer,
and more slender, so that they fall together and variously inter-
mix with each other, and thus it is that the circular disposi-
tion in them is usually more or less concealed from view.
(See Plate LXIV. fig. 4.)

This disposition of the secondary papillae includes of course,
as a consequence, a corresponding arrangement of the blood-
vessels, (a single looped vessel proceeding to each), and of the
nerve filaments, which are in like manner arranged in circles.
(See Plate LXVI. fig. 4.)

The centre of each filiform papilla is hollowed out, and is
to be regarded as a large mucous follicle, and thus the com-

ORGANS OF THE SENSES. 497

parison of these papilla? to a cylinder is rendered almost com-
plete. (See Plate LXIY. Jig. 3.)

We shall presently see that the same circular arrangement
extends to the filiform epithelial appendages hereafter to be
described, and one of which corresponds to each secondary
papilla.*

The fungiform papilla? are seated principally on the tip
and sides of the tongue, at least they are most evident in
those situations, and around each a space or shallow fossa,
dotted with numerous simple papillae, may be observed ; they
are distinguished from the filiform papillae by which they are
surrounded, by their form, being narrow at the base, and di-
lated near the summit, by being clothed all over with simple
papillae, which are usually a good deal compressed in form,
and by the tenuity of the epithelium, destitute of filiform
appendages, which covers them, and which allows of the
blood in the vessels being seen through it. (See Plate
LXIV. Jig. 5.)

At the edges of the tongue, and at the sides behind the
calyciform papilla?, compound papilla? exist, which bear some
resemblance to the fungiform papilla?, of which they may be
described as modifications ; they differ from ordinary fungi-
form papilla?, however, in being sessile and simply rounded; in
the form of the simple papilla? which clothes them, and which
usually are not compressed, but swollen at the extremity, or
pyriform. (See Plate LXV. Jig. 11.)

The calyciform papilla? bound the true gustatory region
posteriorly ; they are seven or eight in number, and arranged
in two rows, which meet behind in the foramen ca?cum, and
enclose a V-shaped space, the concavity of which looks for-
ward.

They each consist of a depression or cup, out of which 'a
large papilla, sometimes more or less adherent to the rim of
the cup, arises, and the level of which it but little exceeds;
the central papilla, as well as the sides and margin of the

* The form and structure of the filiform papillae, as above detailed, was
first described by me in the Lancet of 3rd March, 1 849.

R R 4

498 THE SOLIDS.

cup, are closely set with very many simple papillae, which are
short, obtuse, and dilated at their extremities. A calyciform
papilla, perfectly freed from epithelium, and with all the
secondary papillae visible, forms a very beautiful object. (See
Plate LXVI. fig. 1.)

The foramen ccecum usually contains one and sometimes
two large papilla, similarly clothed with secondary papillae,
and according as it includes one or two papilla, it is to be
regarded as a single or double modified calyciform papilla.

In front of the calyciform papillae, in some tongues, a
number of large and irregular papilla exist, invested with
secondary papillae similar to those of the calyciform papillae,
but not, like the latter, seated in cups.

On the edges and under surface of the tongue numerous
mucous follicles are observed : it is sometimes, however, diffi-
cult to distinguish between these and simple papillae, in
consequence of the latter being frequently perforated in the
centre, and thus combining the characters of both follicles
and papillae. (See Plate LXV. figs. 1, 2, 3.)

The epithelial investment of the tongue adheres very
closely to the papillae, and generally requires one or two
weeks' maceration for its complete removal; even then, in
but few instances in the human subject, can it be removed in
entire pieces, it in most cases crumbling away into its con-
stituent cells.

It adapts itself accurately to the papillary structure of the
tongue, and is of sufficient thickness to conceal effectually
the simple papillae, whether these exist by themselves or con-
stitute by their aggregation the compound papillae. For the
satisfactory study of the papillae, therefore, it is absolutely
necessary that the epithelium should be entirely removed.

The epithelium of the tongue presents all the characters of
the epidermis of the skin, consisting, like it, of numerous
layers of large and nucleated cells, those forming the outer
layers being flattened and membranous, while the deeper-seated
cells are rounded and granular. (See Plate LXV. fig. 6.)

The thickness of the epithelium of the tongue in the human
subject varies very considerably in different cases, and would

ORGANS OF THE SENSES. 499

appear to be much affected by disease ; it in some cases even
being entirely absent.

It is thickest over the simple papilla, which are usually
entirely concealed by it ; over the fungiform and calyciform
papillae it is very thin and delicate, while over the filiform
papilla3 it is prolonged into long filiform processes, which cor-
respond in number and arrangement with the secondary
papillae themselves. (See Plate LIV.^. 1, 2.)

These filiform appendages vary much in length, being very
short upon the sides and near the tip of the tongue, but three
or four times as long near its centre (see Plate LIY. fig. \,
2.) ; at the very tip they are often entirely wanting, the
papillae in this situation presenting the appearance of large open
follicles with slightly spinous rims. (See Plate ~LV.Jiy. 4.)

Each filiform process is constituted of flattened epithelial
scales, which lie in the direction of their length, and fre-
quently contains a canal in its centre.

Tubular nerve filaments, terminating in loops, have been
discovered in the fungiform and filiform papillae, but not
hitherto in either the simple or calyciform papillae, although
nerve filaments, in some form or other, doubtless exist in these
also.

The internal minute structure of. the three principal forms
of compound papillae requires a careful and searching examin-
ation, with a view to the determination of their respective
functions. From a consideration of their outward configura-
tion, they would all appear to be well adapted to receive
gustatory impressions. The fungiform papillae seem to be so
by their prominence and the delicacy of the epithelium by
which they are invested, the calyciform papillae also by the
tenuity of their epithelial covering and by their cupped form,
and the filiform papillae, by reason of the cavity which oc-
cupies the centre of each, and the regular disposition of the
secondary papillae around this.

An additional, and to my mind, indeed, an almost con-
clusive reason in favour of the subserviency of the filiform
papillae to the reception of gustatory impressions, is derived
from the consideration that they cover nineteen- twentieths of

500 THE SOLIDS.

the mucous membrane of the tongue ; and it is but natural
to suppose that the principal portion of this is destined
to the discharge of the function for which it has so evidently
been designed.

The filamentary papillae have generally been considered
to be ill adapted to the reception of gustatory impressions in
consequence of the character of the epithelial processes in
connection with them ; and it has been supposed that they
are to be regarded as tactile rather than gustatory organs.
This opinion has, however, been entertained in the absence
of a full knowledge of the real form and structure of these
papilla?, as already shown.

It has occurred to me that these filamentary processes act
as absorbents of the nutrient juices, and that collectively they
constitute an absorbent surface of considerable power, con-
veying directly to the papilla those fluids, and keeping them
in contact with the papilla? for a time, thus prolonging the
duration of the gustatory impression. . This idea would appear
to gather confirmation from the fact that it is in these fila-
mentary epithelial prolongations that the variable coating
known as the fur of the tongue has its seat.

SMELL.
Structure of the Mucous Membrane of the Nose.

The anatomical characters of the mucous membrane of the
nose differ in different regions ; for a short distance within
the anterior nares, the mucous membrane presents many of
the characters of the skin, it being divisible into chorion,
papillary structure, and epidermis ; the papilla? resemble in
every respect those of the sense of touch, and the epidermis
consists of flattened epithelial scales analogous to those of the
same structure in the skin. This, the commencement of the
nasal mucous membrane, may be called the tactile region of
the nose, and it is abundantly furnished with hairs, which
guard the entrances of the nares, and the roots of which are

ORGANS OF THE SENSES. 501

in connection with the ordinary sebaceous glands of the hair
follicles.

Higher up the mucous membrane of the nose, losing its
papillae and scaly epithelium, becomes thick and soft, and
presents more completely the ordinary appearances of a
mucous membrane ; imbedded in its substance are numerous
mucous follicles of large size, having but small apertures,
which are best seen thickly studding the surface of the mem-
brane after slight maceration and the removal of the epithe-
lium. Between and around these the blood-vessels are dis-
posed, the veins being particularly large, and forming a very
evident plexus, each mesh of which corresponds with a follicle.
(See Plate LXIX.y^. 2.)

The large size and considerable numbers of the mucous
follicles explain the copious secretion which proceeds from
this portion of the mucous membrane, when suffering from
irritation, while the venous plexuses sufficiently account for
the disposition of this part to hemorrhage.

This is by far the largest of the three nasal regions, and
may be denominated the pituatory ; the epithelium which
clothes it is of the ciliated kind, and several of the cavities
in connection with the meatuses are invested by a similar
epithelium, as the fontal and sphenoidal sinuses, the antrum
maxillare, and the Eustachian tubes. In the sinuses, how-
ever, the mucous membrane, losing its follicles, becomes much
reduced in thickness, and presents the characters of a fibrous
rather than of a mucous structure.

Still higher up in the nose we come upon the third region,
which has been particularly defined and described by the
authors of the Physiological Anatomy as follows under the
name of the olfactory region : —

" The olfactory region is situated at the top of the nose,
immediately below the cribriform plate of the ethmoid bone,
through which the olfactory nerves reach the membrane ;
and it extends about one third or one fourth downwards on the
septum, and over the superior and part of the middle spongy
bones of the ethmoid. Its limits are distinctly marked by a
more or less rich sienna-brown tint of the epithelium, and by

502 THE SOLIDS.

a remarkable increase in the thickness of this structure, com-
pared with the ciliated region below ; so much so, that it
forms an opaque soft pulp upon the surface of the membrane,
very different from the delicate, very transparent film of the
sinuses and lower spongy bones. The epithelium, indeed,
here quite alters its character, being no longer ciliated, but
composed of an aggregation of superposed nucleated particles,
of pretty uniform appearance throughout ; except that in
many instances a layer of those lying deepest, or almost
deepest, is of a darker colour than the rest, from the brown
pigment contained in the cells. These epithelial particles,
then, are not ciliated ; and they form a thick, soft, and
pulpy stratum, resting on the basement membrane. The
deepest layer often adheres after the others are washed away.
On looking on the under surface of this epithelium, when it
has been detached, we observe projecting tubular fragments
similar to the cuticular lining drawn out of the sweat-ducts of
the skin, when the cuticle is removed after maceration. In
fact, glands apparently identical with the sweat-glands exist
in this region in great numbers. They dip down in the re-
cesses of the submucous tissue, among the ramifications of
the olfactory nerves ; and their orifices are very easily seen,
after the general brown coat of epithelium has been detached,
lying more or less in vertical rows ; the arrangement is pro-
bably determined by the course of those nerves beneath.
They become more and more sparing towards the limits of
the olfactory region. The epithelium of these glands is
bulky, and, like that of the sweat-glands, contains some pig-
ment. As the duct approaches the epithelium of the general
surface, its wall becomes thinner and more transparent, and,
in its subsequent course upwards, it is difficult to be traced,
for it does not appear to be spiral, or its particles to differ
from those which they traverse. We have sometimes seen
rods of epithelium, apparently hollow, left projecting from
the basement membrane, after the brown epithelium has been
washed away, and these are perhaps portions of the excretory
ducts of these glands."

In the propriety of the discrimination of this region, and

ORGANS OF THE SENSES. 503

in the accuracy of much of the description of it given above,
the author fully concurs. He does not, however, hesitate to
affirm that no glands at all analogous to sweat-glands exist
in it ; the membrane of this region is indeed thickly studded
with mucous follicles, apparently in no respect dissimilar to
those of the pituatory region, except that they are smaller in
size, and more delicate in structure.

The chief characteristics of the olfactory region consist,
then, in its glandular epithelium, in the presence of pigment
cells lying beneath this, in its more delicate structure, in the
presence of gelatinous nerve filaments, and in a somewhat
different arrangement of the blood-vessels. (See Plate LXIX.

fig- !•)

In the sheep this region is rendered almost black by the
presence of very many pigment cells which are of the stellate
form.

Mr. Quekett pointed out, some years ago, the very curious
fact that the blood-vessels of the olfactory region of the
human foetus, and that of mammalia in general, are disposed
in loops, the convexity of each of these presenting a decided
dilatation. (See Plate LXIX./^. 12.)

Much interest is attached to the existence of these loops,
since they appear to indicate the presence of true papillae in
the seat of smell of the mammalian foetus ; if such be the
case, however, it is very certain that neither the papillae nor
loops exist in the olfactory region in the adult condition of
the nasal organ.

The most rigorous search has failed to detect the presence
in the olfactory region of cells, which could be decidedly pro-
nounced to be nervous or ganglionic.

The nerves of the nose are the first pair, branches of the
fifth, and motor filaments from the seventh pair. The first
pair are, doubtless, the proper nerves of smell, while the fifth
gives common sensibility to the nose.

The olfactory lobes are prolongations of the white or
fibrous portion of the brain, and consist, like it, of slender
tubular nerve filaments, intermixed with the delicate trans-
parent cells, described in a previous division of this work.

504: THE SOLIDS.

" The olfactory filaments are from fifteen to twenty-five in
number, and passing through the apertures of the cribriform
plate, may be seen invested with fibrous sheaths derived from
the dura mater, upon the deep or attached surface of the
mucous membrane of the olfactory region. They here branch,
and sparingly reunite in a plexiform manner, as they descend.
They form a considerable part of the entire thickness of the
membrane, and differ widely from the ordinary cerebral nerves
in structure. They contain no white substance of Schwann,
are not divisible into elementary fibrillas, are nucleated, and
finely granular in texture ; and are invested with a sheath of
homogeneous membrane, much resembling the sarcolemma,
or, more strictly, that neurilemma which we figured from the
nerves of insects in a former volume. These facts we have
repeatedly ascertained, and they appear to be of great im-
portance to the general question of the function of the several
ultimate elements of the nervous structure, especially when
viewed in connection with what will be said on the anatomy
of the retina. We are aware that some anatomists deny the
existence of the white substance of Schwann as a natural
element of the nerve fibre in any case, pretending that it is
formed by artificial modes of preparation. We hold it to be
a true structure, but however that may be, these nerves
never exhibited it, however prepared. They rather corre-
spond with the gelatinous fibres. Now there is no kind of
doubt that they are a direct continuation from the vesicular
matter of the olfactory bulb. The arrangement of the capil-
laries in well-injected specimens is a convincing proof of this,
as these vessels gradually become elongated on the nerve
assuming a fibrous character as it quits the surface of the
bulb ; and, further, 110 tubular fibres can ever be discovered
in the pulp often left upon the orifices of the cribriform plate
after detachment of the bulb. It must be remembered that
a few tubular fibres from the nasal nerve of the fifth here
and there accompany the true olfactory filaments ; but these
only serve to make the difference more evident by contrast."
— Physiological Anatomy.

ORGANS OF THE SENSES. 505

VISION.
Structure of the Globe of the Eye.

The structure of the several appendages of the globe of
the eye : as the eye-lids, with their lashes, and Meibomian
glands, the caruncula lacrymalis, the lachrymal gland, muscles,
&c., have already been fully described in previous sections of
this work ; we have now to enter upon the description of the
numerous parts which compose the essential portion of the
organ of vision, the globe of the eye ; each of these may be
examined in much the same order in which they would
naturally present themselves to the notice of an ordinary
dissector, and which would be somewhat as follows. Schle-
rotic and cornea ; choroid, ciliary processes, and iris ; retina ;
crystalline lens ; hyaloid membrane, &c.

Schlerotic.

The schlerotic is composed, to a great extent, of white
fibrous tissue, intermixed with a small proportion of a nu-
cleated form of elastic tissue.

These tissues are disposed in a laminated manner, the fibres
of one layer crossing those of another more or less at right
angles ; an arrangement evidently designed to render this the
protecting tunic of the eye more firm and unyielding. The
inner surface of the schlerotic is rough, and connected with
the choroid by the lamina fusca of that membrane, to be
described hereafter.

The nutrition of the schlerotic is provided for by small
vessels, which ramify on its outer surface, and which are
sparingly continued into its substance.

Anteriorly, the schlerotic is strengthened by the tendinous
expansion of the four recti muscles, known as the tunica
albuginea, or white of the eye.

506 THE SOLIDS.

Cornea.

The cornea, although in a state of health as clear as
crystal, yet possesses a complicated and beautiful organis-
ation, plainly demonstrable with the aid of the microscope.

Notwithstanding also the definite line of demarcation by
which the limits of the cornea and schlerotic are marked out,
these two parts are yet inseparably united to each other ;
this indissoluble union depending upon the circumstance of
the existence of a structural connection between them, the
nature of which will shortly be rendered evident.

The cornea is clearly divisible into four, and, according to
some observers, even five laminae ; these are, reckoning from
before backwards, conjunctival epithelium, cornea proper,
posterior elastic lamina, and the epithelium of the aqueous
humour ; the fifth layer has been described in the " Physio-
logical Anatomy " under the title of the " anterior elastic
lamina." These several layers will be separately noticed, and
in the order mentioned. (See Plate LXVII. Jig. 1.)

The conjunctival epithelium forms a distinct membrane of
appreciable thickness and capable of separation as such shortly
after death. It consists of several layers of superimposed
cells, which partake of many of the characters of ordinary
epidermic scales or cells.

Those cells which constitute the outer or more superficial
layers are large, flat, and membranous ; whilst those nearest
to the cornea proper, and which appear to rest directly upon
it, are baton-shaped, and disposed vertically to the surface of
the cornea. (See Plate LXVIII./^. 3. 5., and Plate LXVII.
fig. 1.)

After death this epithelium becomes whitish and opaque,
and it then forms the film of the eye.

The second lamina, according to the observations of the
author, is the cornea proper ; and it is this which constitutes
the principal bulk of that structure.

Externally, the cornea proper is firm and dense in texture,
but becomes more lax and soft gradually as we approach the

ORGANS OF THE SENSES. 507

interior ; it is this external and firmer portion which exhibits
the lamellar arrangement so generally described, the fibres
following a less regular course internally, and being separated
by wider intervals.

The tissue of the cornea has been recently described as a
peculiar modification of the wrhite fibrous element of the
schlerotic. It would appear, however, that the fibrous tissue
of which it is constituted is of a kind totally distinct from
that which enters so largely into the composition of the cornea
proper ; a conclusion derived from its examination, for which
we might be prepared, simply by the consideration of the
very opposite physical characters of the two parts, the schle-
rotic and cornea, the former being white and opaque, and the
latter clear and diaphanous.

If we tear up with needles a small portion of the schlerotic,
and examine it with the microscope, we then see that it is
made up, for the most part, of bundles of wavy and distinct
fibres, presenting scarcely a nucleus, and reflecting a yellowish
hue ; if now we carry our examination still further, and apply
acetic acid to these bundles, they swell up, the fibres be-
coming indistinct, and finally converted into a jelly-like
substance.

On the other hand, if we submit a portion of the cornea
to the same examination, and the same treatment by acetic
acid, we shall encounter different appearances and results. In
the first place, we shall not perceive distinct and separate
bundles of fibrous tissue free from nuclei, but we shall merely
notice an indistinct fibrous character in the mass, with here
and there elongated nuclei imperfectly seen ; on the applica-
tion of acetic acid, however, the fibres become much more
evident, and multitudes of nuclei are brought into view.
Thus, then, it is evident that the tissue of the cornea is some-
thing more than a modification of the white fibrous element
of the ,schlerotic. The nucleated fibres just described are
often, in the neighbourhood of the nuclei themselves, ex-
panded and membraneous ; and it is remarkable that they do
not lie in direct apposition with each other, but interlace in
such a manner as to describe elongated spaces, several of

3 S

508 THE SOLIDS.

which are extended in the same line. These spaces are oval
in the cornea, and round in that portion of the schlerotic
where the two structures are in connection with each other.*
(See Plate LXVII. fig. 3.)

This arrangement was first pointed out by the authors of
the " Physiological Anatomy," and is thus described by them.
" On the cornea proper or lamellated cornea, the thickness
and strength of the cornea mainly depend. It is a peculiar
modification of the white fibrous tissue, continuous with that
of the schlerotic. At their line of junction, the fibres, which
in the schlerotic have been densely interlaced in various di-
rections, and mingled with elastic fibrous tissue, flatten out into
a membraneous form, so as to follow in the main the curva-
tures of the surfaces of the cornea, and to constitute a series
of more than sixty lamella?, intimately united to one another
by very numerous processes of similar structure, passing from
one to the other, and making it impossible to trace any one
lamella over even a small portion of the cornea. The result-
ing areola?, which in the schlerotic are irregular, and on all
sides open, are converted in the cornea into tubular spaces,
which have a very singular arrangement, hitherto undescribed.
They lie in superposed planes, the continuous ones of the
same plane being, for the most part, parallel, but crossing

* A subsequent examination of the cornea renders it necessary that
the views above expressed of its structure should be modified to some
extent. I find that a considerable amount of a tissue, very closely re-
sembling the white fibrous tissue of the schlerotic, does enter into the
construction of the cornea ; in sections, however, whether treated or
not with acetic acid, this tissue is scarcely to be traced, the nuclear form
of fibrous tissue already described, and which is so very abundant, being
alone visible, and appearing to constitute the entire of its substance.
If, however, a small piece of the inner and softer part of the cornea be
torn up with needles, and then examined, bundles of fibrous tissue, very
analogous to those of the white fibrous form, will be plainly seen ; these
are of considerable diameter, reflect a greenish shade, and are, in many
parts, transversely striated, each filament bearing a resemblance to a minute
Conferva ; they are rendered nearly, though not quite, invisible by the
action of vinegar. Considered altogether, the cornea resembles very
closely, in structure, a tendon, which also contains a very large quantity
of a similar nuclear fibrous tissue.

ORGANS OF THE SENSES. 509

those of the neighbouring planes at an angle, and seldom
communicating with them. The arrangement and size of
these tubes can be shown by driving mercury, or coloured
size, or air into a small puncture made in the cornea. They
may also be shown under a high power by moistening a thin
section of a dried cornea, and opening it out by needles."
In addition to the above it may be remarked, that the spaces
may be seen without injection, or any other preparation even
in perfectly fresh eyes.

In vertical sections of the cornea, after the application of
acetic acid, the nucleated fibres in its outer and denser por-
tion are seen to follow the curved form of the cornea itself,
while in its inner and softer part they are variously disposed ;
horizontal sections of the cornea, even taken from the surface,
exhibit a curved and interlaced arrangement of the fibres ;
fibres also nucleated pass from the surface of the cornea
deeply into its substance: the use of these is doubtless to
assist in preserving its convexity. (See Plate LXVIL fig. 1.)

The posterior elastic lamina is the third layer of the
cornea: it is a perfectly transparent membrane of appreci-
able thickness, so that it may be readily recognised with
the unaided sight, and is but slightly attached to the cornea
proper.

It is usually described as structureless, and in most cases
it certainly is so, but in the human eye it frequently exhibits
peculiar markings, portrayed in Plate LXVII. Jigs. 11, 12.
These, however, would appear to proceed from definite in-
equalities of the surface rather than from any distinct fibrous
or cellular tissue ; nevertheless, the appearances observed are
remarkable and worthy of record.

This lamina preserves its transparency even in boiling water
and acetic acid ; and a further peculiarity is, that although it
may be torn in any direction, it is so hard that it can be bitten
through, only with difficulty. It extends to the margin of
the cornea only, where it comes into connection with certain
elastic fibres to be described hereafter.

The epithelium of the aqueous humour is the fourth layer

ss 2

510 THE SOLIDS.

of the cornea : this is of such delicacy and tenuity as to be
readily overlooked ; it consists of angular cells which form a
tesselated epithelium, and rests upon the posterior surface of
the elastic lamina above described. (See Plate L XVIII.
Jig. 11.) This epithelium is doubtless concerned in the
secretion of the aqueous humour, but it does not appear to
extend beyond the limits of the elastic lamina.

The fifth layer, to which reference has already been made,
is the anterior elastic lamina, which is described in the third
part of " Physiological Anatomy " as follows : — " This is a
transparent homogeneous lamina co-extensive with the front
of the cornea, and forming the anterior boundary of the
cornea proper. It is a peculiar tissue, the office of which
seems to be that of maintaining the exact curvature of the
front of the cornea ; for there pass from all parts of its pos-
terior surface, and in particular from its edge into the sub-
stance of the cornea proper, and schlerotic, a multitude of
filamentous cords, which take hold, in a very beautiful arti-
ficial manner, of the fibres and membranes of those parts, and
serve to brace them and hold them in their right configura-
tion. These cords, like the elastic lamina of which they are
productions, appear to be allied to the yellow element of the
areolar tissue. They are unaffected by the acids. The an-
terior elastic lamina sustains the conjunctival epithelium
which covers the cornea, and is very probably a representa-
tive of the basement membrane of the mucous system, as it
occupies the corresponding position in regard to the epithe-
lium."

The writer has made diligent and repeated search for
this lamina, or for any structure resembling it, without
success however ; and he has no hesitation in asserting
his disbelief in the existence of any membrane in the
slightest degree analogous to the posterior elastic lamina in
the situation indicated : he is not prepared, however, to deny
the presence of an exceedingly thin layer of structureless
basement membrane, although of this even he has not yet
discovered any evidence, but conceives it possible that it
may exist. Its detection has been attempted in several ways ;

ORGANS OF THE SENSES. 511

namely, by vertical and horizontal sections, and by the use of
re-agents, but to no purpose.

In a representation of a vertical section of the human
cornea given in the " Physiological Anatomy," this anterior
elastic lamina is represented as being three or four times the
thickness of the posterior lamina, so that there ought to be
but little difficulty in its detection were it present on the
face of the human cornea.

The " elastic cords " mentioned would appear to be nothing
more than the nucleated fibres already described as passing
in a curved manner from the surface of the cornea, and
extending deeply into its substance. (See Plate LXVII.

fig. i.) '

Choroid.

The next membrane met with in the usual order of dissec-
tion, is the choroid : this adheres intimately to the schlerotic
in the neighbourhood of the larger trunks of the venae vor-
ticosaj; but more slightly in the intervals between, being
united to it only by the lamina fusca.

The choroid forms a thick membrane, externally of a
chocolate colour, flocculent and rough, but internally of a
bluish-black colour and smooth; its substance is made up
of numerous blood-vessels, and of an immense quantity of
pigment in connection with a peculiar form of fibrous tissue.

The tissue of which the choroid is composed, has been
hitherto stated to resemble the fibrous tissue of the schlerotic :
this is not the case, however, as indeed might have been in-
ferred from the ease with which it tears, especially in the
course of the vessels, and the absence of bundles of fibres on
the torn and divided margins : the fibrous element of the
choroid is of a peculiar kind, to be more fully described here-
after, and unlike any other form existing in the human body.

The blood-vessels of the choroid are usually described as
forming two layers, and this they may be fairly considered
as doing, although the two lamellse are not perfectly distinct
from each other, being connected by numerous blood-vessels
which pass between them.

s s 3

512 THE SOLIDS.

These laminae may be designated in general terms sepa-
rately as arterial and venous : the inner or arterial lamina,
known as the tunica Ruyschiana, consists of a dense and
beautiful plexus of vessels, which are so closely applied to
each other as scarcely to leave any intervening spaces or
meshes. (See Plate LX VII. Jig. 4.) The main arteries which
supply this tunic, and the veins which carry off its blood,
leave it by numerous points on its outer surface only ; the
veins are particularly large and numerous, and disposed in
beautiful curves, whence they are called vencR vorticosce. (See
Plate LXVIII. fig. 2.) Before leaving the choroid they
converge to form four or five principal trunks which enter
the schlerotic ; the arteries, fewer in number and much smaller
in size, run between the veins.

An immense number of granular nuclei are visible in the
walls of the venae vorticosae.

Stellate choroidal epithelium. — Such is the distribution of
the blood-vessels of the choroid: the next most important
element in its constitution are the pigment cells ; these exist
in vast quantities and make up much of its substance ; they
are of various forms and sizes ; but being furnished with two,
three, or more arms or radii, they may be aptly termed stel-
late. The nucleus in each cell is large and particularly clear,
appearing almost like a hole in its centre : this is owing to
the absence of the colouring matter contained in each cell
in that situation.

The existence of the stellate form of pigment cells in the
human subject appears to have been generally overlooked : it
was described and figured in Parts 7 and 8 of the Microscopic
Anatomy published in February and March, 1847, and its
arrangement in rows was at the same time pointed out ; its
position in the choroid, as well as its structure, have since
been examined with more care, and with the following re-
sults.

This pigment is situated beneath the tunica Ruyschiana,
and in the intervals between the venae vorticosae, which it
accurately fills up, some of the arms of the cells, as well as
occasionally a few of the scattered cells, intrenching upon

ORGANS OF THE SENSES. 513

the veins : thus, then, its disposition is a counterpart of
that of the venae vorticose, the dense rows of cells exhibit
the same curves, the same mode of branching, and viewed
altogether with a low object-glass in the eyes of some
animals, as the sheep, nothing can exceed the beauty and
elegance of the object thus presented to our examination.
(See Plate LXVIII. fig. 1.)

With regard to structure, it is remarkable that each radius
or arm of the cells is prolonged into a colourless fibre, in the
course of which several other cells may be included. (See
Plate LXVIII. fig. 13.)

This structure is best seen in the lamina fusca, the fibres
of which are all of this nature, and are exceedingly dia-
phanous, often membranous, much disposed to curl up, and
unaffected by distilled vinegar, beyond undergoing a degree
of contraction. All the fibres met with in the choroid, ex-
cept those entering into the constitution of the blood-vessels,
are of this peculiar nature.

The inner surface of the choroid is so smooth as to convey
the impression of the existence of a distinct membrane : of
this, however, no satisfactory evidence has yet been obtained,
although portions of membrane apparently devoid of struc-
ture have been seen on the margins of torn portions of
the choroid. If a membrane does really exist in this situ-
ation, it is possible that it is nothing more than the vessels
of the tunica Ruyschiana united into a membrane by the
fibres above described.

Hexagonal choroidal epithelium. — On the inner surface of
the choroid a layer of cells of a regularly pentagonal or
hexagonal form, filled with pigmentary granules, exists :
these cells are so coherent that they form a distinct layer
much more evident in the eyes of some animals, as the sheep
and pig, than in those of man. (See Plate LXVIII. fig. 12.)

This layer extends over that peculiar structure common
to the eyes of many quadrupeds and fishes, the tapetum luci-
dum ; but in that situation its component cells are of smaller
size, and almost entirely deprived of colouring matter.

In albinoes the colouring matter is deficient, not only in

s s 4

514 THE SOLIDS.

the cells of tapetum lucidum, but also in those of the hexa-
gonal and stellate choroidal epithelium.

The tapetum lucidum is a layer of fibrous tissue implanted
upon the choroid, possessing the remarkable property of re-
fracting unequally the rays of light which fall upon it, and
hence its brilliancy and metallic lustre : acetic acid destroys
to some extent this peculiarity ; the stellate pigment is con-
tinued behind the tapetum lucidum, which singular and
beautiful structure acts as a concave reflector, its use being to
economise light and to cause the rays to traverse the retina a
second time, by which means animals possessing it are enabled
to discern objects in a light which would be insufficient for
the purpose in the absence of such a provision.

The description of the choroid now given includes that
portion of it only which corresponds to the retina, and
which ceases at a line known as the ora serrata ; about the
eighth of an inch behind the margin of the cornea, in front
of this line as far as the iris, the choroid is known as the
ciliary body ; this is covered behind by a layer of non-striated
muscular fibre, the ciliary muscle (see Plate L XVIII. Jig. 4.),
and from it the ciliary processes descend.

Ciliary processes. — These processes, usually reckoned at
about sixty in number, are received into corresponding folds
or plaitings of the hyaloid membrane, called the secondary
ciliary processes, and which taken altogether form a circle
around the crystalline lens named after their discoverer the
Zone of Zinn : they are each composed of numerous blood-
vessels (see Plate LXYII. fig. 4.), fibrous tissue, irregular
pigment cells ; and " on their inner surface is a tough colour-
less lamina, composed of ill-defined nucleated cells continuous
with the border of the retina, but clearly not composed of
nervous matter, by means of which they are immediately con-
nected with the hyaloid membrane."

The iris may be regarded as an extension of the choroid,
although it does not exhibit all the anatomical characters of
that membrane ; it is made up of a considerable quantity of
pigment cells, of blood-vessels, and of fibres of unstriped
muscle. (See Plate LXVIII. fig. 9.)

ORGANS OF THE SENSES. 515

The pigment cells constituting the posterior layer of the
iris, and called uvea, are irregular in size and form, as are
those also situated amongst the fibres of the iris ; upon the
varieties in the colouring matter contained in these last, many
of the differences observable in the iris of different persons
and animals depend. (See Plate LXVIII.jfy. 14.)

The muscular fibres of the iris in the human subject are
of the uristriped kind and follow two courses, a radiating and
a circular ; in birds, however, the radiating fibres consist of
striped muscular fibres, and they surround immediately the
pupil ; the one set of fibres dilates the pupil, the other con-
tracts it.

The blood-vessels of the iris are very numerous, and are
derived chiefly from the two long ciliary arteries, which on
approaching the iris bifurcate and form an arch around it,
whence pass inwards a number of branches which form
loops near the pupillary margin.

" On the anterior surface, near the pupil, a vascular circle
marks the line from which in the foatus the membrana pu-
pillaris stretched across in front of the pupil. This membrane
at that early period divides the posterior from the anterior
chamber, and receives from several parts of the circular vessel
last mentioned small branches, which approach the centre
and then return in arches after inosculating sparingly across
the central point." The membrana pupillaris is almost ab-
sorbed at birth.

The iris, according to the authors of the Physiological
Anatomy, " is attached all round at the junction of the
schlerotic and the cornea, so near indeed to the latter that its
anterior surface becomes continuous in the following manner
with the posterior elastic lamina. This lamina, near its border,
begins to send off from its anterior surface, or that towards
the laminated cornea, a network of elastic fibres, which
stretch towards the border, becoming thicker as they ad-
vance, until at length the entire thickness of the lamina is
expended by being converted into them. These fibres then
bend backwards from the whole circumference of the cornea
to the circumference of the front of the iris, and are there

516 THE SOLIDS.

implanted, passing in this course across the line of the an-
terior chamber and through the aqueous humour. They are
seen more easily in some animals than in others, forming a
regular series of pillars around the anterior chamber."

It would appear, however, that these fibres, which may be
readily detected in the human eye, should rather be described
as proceeding from the schlerotic, and passing, some on the
anterior surface of the elastic lamina, and others on the front
of the iris, thus assisting in uniting these parts to that tunic ;
it is very doubtful whether they have any structural connec-
tion with the posterior elastic lamina. (See Plate LXVIII.
fig. 8.)

The ciliary nerves pierce the ciliary muscle on their way
to the iris.

Retina.

We come in the next place to the description of the most
interesting and important of the many structures which
enter into the composition of the globe of the eye, namely,
the retina. This membrane may be regarded as the expan-
sion of the optic nerve, to which certain other structures
are superadded, and, like most of the other membranes of
the eye, is divisible into distinct lamellae ; these, reckoning
from without inwards, are, tunica Jacobi, or " stratum bacil-
losum," the granular or nuclear layer, the ganglionary layer,
the vesicular layer, the fibrous expansion of the optic nerve,
and, lastly, the vascular expansion of the arteria centralis
retinae.

The tunica Jacobi is composed of a single stratum of cells of
very remarkable form. They are minute in size, several times
longer than broad, having their long axes disposed vertically
to the general surface of the retina, and they each consist of
a body or head of a more or less globular or oval shape, and
of a prolongation or tail, four or five times longer than the
head, and not more than a third of its diameter. By their
coherence these cells form a distinct membrane, the heads of
the cells all being directed one way, namely, towards the

ORGANS OP THE SENSES. 517

surface of the choroidal epithelium, and the tails disposed in
an opposite direction. Although these cells adhere together
with sufficient firmness to constitute a distinct membrane, it
would appear that they possess a certain power of movement
upon each other, for it is only on such a supposition that we
can explain satisfactorily the fibrous appearance which this
membrane frequently presents when viewed in extenso. (See
Plate LXYII. fig. 9.)

The tunica Jacobi, although certainly not a nervous struc-
ture, is yet properly enumerated as one of the layers of the
retina, since it never adheres on the removal of the latter to
the choroidal epithelium, but always to the second or granular
layer of the retina itself : on account of its extreme frailty
and delicacy, this membrane is only to be satisfactorily
studied in extremely fresh eyes. A few hours after death
the cells separate from each other, and the heads of the cells
become disjointed from the tails, so that in the course of a
short time not a vestige of the membrane remains.

Each cell of the stratum bacillosum bears not an inexact
resemblance to a human spermatozoon, than which it is how-
ever less considerable in size.

The granular layer consists not of granules merely, as the
name implies, but of numerous nuclei imbedded in granular
matter, and each of which contains several dark spots which
reflect the light strongly. This layer is of considerable thick-
ness, and is described in the "Physiological Anatomy" as being
divided into two, of which the inner is much the narrower,
by a pale stratum which can only be seen by very careful
manipulation. The nuclei of which it is composed bear much
resemblance to those which occur in the convolutions of the
brain, and are most probably of the same nature. (See Plate
LXVII. figs. 5, 6.)

The next is the ganglionary layer: this appears to have
been hitherto altogether overlooked ; its discovery supplies a
desideratum in the anatomy of the eye, and clearly shows
the really nervous character of the granular and vesicular
strata of the retina, which many persons have been much
disposed to doubt.

518 THE SOLIDS.

This layer is exceedingly thin and delicate, hardly indeed
to be considered as a distinct stratum, but yet consisting of
numerous caudate ganglionary globules, in every respect
similar in point of structure to those which have been de-
scribed as occurring in so many of the ganglia of the human
brain.

These caudate cells differ considerably in size, but yet are
all referable to one of two standards, the larger very much
exceeding the smaller in dimensions. (See Plate LXVIL
fig. 8.) .

It is in the human retina only that these cells have as yet
been detected.

The fourth or vesicular layer lies immediately on the outer
surface of the fibrous layer, the cells composing it are several
times larger than the nuclei of the granular layer ; a few of
the most external of them are granular and nucleated, but
the majority, and these the larger cells, are clear and trans-
parent as water, perfectly globular, and without appreciable
nuclei. The cells of the vesicular layer resemble very closely
the delicate cells which have been described in a previous
part of this work, as found in the fibrous portions of the
human brain. (See Plate LXVIL fig. 7.)

The fibrous gray layer is best seen and most strongly
marked in the retina near to the optic nerve. If a portion of
this membrane be cut off and spread out upon glass, it will
be seen to present, viewed with the inch or half-inch object-
glass, a number of parallel or rather radiating flattened bands,
two of which occasionally divide or bifurcate.

If, in the next place, these bands or bundles, having been
separated somewhat from each other by means of needles,
and as much, of the granular layer which so obscures them
washed away with a camel's hair brush as possible, be then
examined, they will each be observed to present a fibrous
appearance, and on a prolonged and careful examination it
will become apparent that they are made up, first, of a small
quantity of nucleated fibrous tissue, and, secondly, and prin-
cipally, of gray gelatinous, nerve fibres. (See Plate LXVIII.
Jig. 6.)

ORGANS OF THE SENSES. 519

That these gelatinous fibres constitute the principal portion
of the fibrous layer of the retina, and that no tubular nerve
fibres exist in the retina itself, are points upon which not the
smallest doubt can be entertained.

Of the reality of the transformation of the tubular into
the gelatinous nerve filament, that is, the conversion of a
tubular, unbranched, and unnucleated structure into a
branched, and nuclear tissue, great misgivings might be well
entertained ; an attentive study of the structure of the fibrous
gray layer of the retina renders it very difficult, however, to
deny the reality of such a structural transition.

The vascular lamina is the last of the layers of the retina :
it would appear to be entirely distributed upon the inner
surface of the fibrous layer ; for if we take a perfectly fresh
eye and spread the retina out with its inner surface upwards,
we can readily see the larger blood-vessels filled with blood
corpuscles, and having the fibrous layer situated immediately
behind them. (See Plate LXVII. fig. 2.)

The optic nerves consist of several bundles of nerve tubules :
these are very slender and brittle, and interspersed with deli-
cate globular cells ; in these last two particulars these nerves
correspond with the white fibrous portions of the brain.

The transparent media of the eye are the vitreous body and
the crystalline lens with its capsule.

Vitreous Body.

The vitreous humour is enclosed in a perfectly structureless
and exceedingly delicate membrane called the hyaloid mem-
brane : this does not enclose the whole of the vitreous
humour, but is deficient behind the crystalline lens, it being
inserted into the side of the capsule of that body.

From all points of the inner surface of this membrane
fibres proceed; these interlace with each other in such a
manner as to form a cellated structure.

The size and structure of these cells may be readily seen
with an inch or half-inch object-glass ; and the best view of

520 THE SOLIDS.

them is obtained in the neighbourhood of the zona ciliaris.
(Plate LXVIII. fig. 7.)

Granular nuclei of large size are seen on the walls of the
cellated spaces ; these are most probably concerned in the
secretion of the vitreous humour. That these several cellated
spaces communicate with each other, seems proved by the fact
that if the hyaloid membrane be ruptured, the whole of the
vitreous humour will gradually escape through the aperture.

A layer of cells of large size and of such extreme trans-
parency as to be discovered only with great difficulty, are
described in the " Physiological Anatomy " as situated on the
hyaloid membrane between it and the retina : these have not
fallen under the observation of the writer.

The vitreous body, then, consists of the hyaloid membrane,
cellated fibrous structure, the zone of Zinn, and of the vitreous
humour. Through the centre of this body a branch of the
central artery of the retina passes in early life, destined for
the posterior part of the capsule of the lens.

Crystalline Lens.

The crystalline lens is composed of capsule and body.

The capsule is formed of a thin lamella of elastic tissue,
much thicker before than behind, but in all essential par-
ticulars similar to the posterior elastic lamina of the cornea.
The manner in which it is attached to the hyaloid membrane
has been already pointed out ; it now remains to observe
that the cellated fibres of the vitreous body are also inserted
into its posterior part. It is perfectly closed on all sides, so
that in the adult condition of the eye neither vessels nor
nerves pass through it to the lens.

The body of the lens, transparent and jelly-like as it ap-
pears to the unaided sight, is yet full of elaborate and elegant
structure. It consists of very many layers or concentric
lamellae of flattened fibres, which radiate from the centre and
are disposed in a parallel manner with reference to each
other; the fibres, however, have a more complicated ar-
rangement than this, as will be evident from what follows.

ORGANS OF THE SENSES. 521

In the Mammalia in general there are visible on the front
surface of the lens, when this has slightly lost its trans-
parency, three radiating grooves or lines, the points of which
terminate at about one-third from the border of the lens.
On the opposite surface of the lens there exist three similar
lines, occupying an intermediate position. From these lines
the fibres pass from the one surface on to the other ; thus a
fibre which starts from the point of one of the lines in front,
passes over the border of the lens, advances midway between
two lines on the opposite surface, and is inserted in the
angle of division of those lines ; another fibre starting from
between two lines in front, is lost on the extremity of a line
situated posteriorly : the rest of the fibres occupy positions
intermediate to these. If, in the next place, we bear in
mind the fact that these lines, seen on the surface of the
lens, are but the edges of planes which pass through the
centre of the lens, affording points of divergence and con-
course for all the fibres, deep as well as superficial, we shall
readily comprehend what, without this explanation, would
have appeared an intricate arrangement ; and we shall per-
ceive why it is that the lens, when hardened in spirit or
boiled in water, is prone to separate into concentric lamella
and into three triangular segments. From the above ar-
rangement it results, also, that all the fibres, whether super-
ficial or deep-seated, decrease in width as they approach the
centre of the lens on either surface, and also that the super-
ficial are longer and larger than the deeper seated. (See
Plate LX VII. fig. 13.)

The edges of the fibres are most beautifully toothed and
dovetailed together, as was first pointed out by Sir David
Brewster. This toothing is best seen in the eyes of fishes ;
it is also clearly manifest, although on a smaller scale, in the
fibres of the lens of most mammalia and of man. (See
Plate LXVIL^. 10.)

On the surface of the lens beneath the capsule, and occu-
pying the space between these, a delicate epithelium exists,
very similar to that on the posterior elastic lamina. (See

522 THE SOLIDS.

Plate LXVIII. fig. 10.) After death, this space is occupied
by a small quantity of fluid, the liquor Morgagni.

Beneath this epithelium, again, other small oval granular
cells are encountered ; from these possibly the fibres of the
lens take their origin.

The lens is of less density externally than internally ; this
is also one of the results of the peculiar form and arrangement
of the fibres.

In the adult eye the lens is entirely destitute of blood-
vessels, although during its development in the foetus it is
copiously supplied with them.

THE ORGAN OF HEARING.

ELABORATE as is the organisation of the ear, it yet presents
less to interest the microscopical anatomist than many other
of the organs which enter into the composition of the human
fabric. The ear is divisible into three portions — the limits
of each of which are well defined — an external, a middle, and
an internal: the external portion is an apparatus for the
collection of sound ; the middle is designed for its convey-
ance to the internal or true and essential division of the
organ of hearing.

The External Ear.

The external ear consists of the expanded part or auricle,
and the external meatus.

The auricle. The auricle presents several eminences and
depressions, many of which have received distinct names ; it
is made up of integument, cartilages, and fat ; the integu-
ment is thin and delicate, and is furnished with but few seba-
ceous glands ; the cartilages are of the fibrous kind, and are
three in number, — the larger forming the pinna, being sepa-
rated from that of the tragus and antitragus, by grooves
filled up with fibrous tissue ; lastly, the fat is situated
chiefly in the lobe of the ear. Ligamentous bands bind the

ORGANS OF THE SENSES. 523

auricle to the bone, while its movements are effected, in part,
by muscular fibres which pass between the prominent parts of
its constituent cartilages, but mainly, by three small muscles
of the striped variety, and each of which has received a dis-
tinct name.

The Auditory Canal. — The auditory canal consists of two
parts, — a cartilaginous and an osseous ; the first is formed
by the prolongation inwards of the cartilages of the auricle ;
these form a tube, deficient at the upper and back part,
where the place of cartilage is supplied by a fibrous mem-
brane ; this tube is inserted into the auditory process of
the temporal bone : the osseous part of this canal is formed
by the auditory process already alluded to ; this process in
the adult is nearly three-quarters of an inch long, and to its
outer margin the tympanum is attached, the bone being
grooved for its reception : in the foetus, the auditory process
is a detached ring of bone, into which, however, the tym-
panum is inserted.

The orifice of the rneatus is defended by hairs, the bases
of which are in connection with sebaceous glands ; still
further inwards, but limited to the cartilaginous part of the
passage, the ceruminous glands are encountered : these have
already been described.

According to some observers, muscular fibres exist in the
external meatus, which becomes shortened by their con-
traction.

The Middle Ear.

The middle ear consists of the tympanum, tympanic cavity,
and the ossicles with their muscles.

The tympanum, or tympanic membrane, is divisible into
three laminas — an external or cuticular, a middle or fibrous,
and an internal or ciliated ; the external is a continuation of
the cuticle which lines the external meatus, and may be
separated as a distinct membrane; the fibrous tissue, of
which the internal lamina of the tympanum is composed, is
strong and dense, and is arranged in a radiated manner ; into

T T

524 THE SOLIDS.

this the handle of the malleus is inserted : the blood vessels
which supply the tympanum pass along the handle of the
above-named bone, and follow the same radiated course as the
fibres themselves ; the inner and third lamina is composed of
cells of ciliated epithelium, similar to those lining the tym-
panic cavity.

* The tympanic cavity is lined by a fibrous membrane, divisi-
ble into two layers ; the fibres entering into the composition
of one of these follow a longitudinal course, while those of
the other layer are circularly disposed ; these fibres are, for
the most part, nucleated, and would appear to be of the
elastic kind : in the longitudinal layer, the fibres are dis-
posed in bundles, and are possibly contractile : on the surface
of this membrane and lining immediately the tympanic
cavity, is a layer of ciliated epithelium, continuous on the
one hand with that of the tympanic membrane ; and on the
other, with that clothing the interior surface of the Eusta-
chian tube.

Posteriorly, the tympanic cavity exhibits the openings of
the mastoid cells ; anteriorly, the orifice of the Eustachian
tube may be noticed, while the internal wall of the tym-
panum presents two orifices which communicate with the
internal ear: these are the fenestra ovalis, leading into the
vestibule ; and the fenestra rotunda, opening into the cochlea.

The whole length of the tympanic cavity is traversed by a
chain of three bones, united to each other by muscles of the
striped kind ; one extremity of this chain is attached, as
already noticed, to the tympanum, while the other, formed by
the base of the stapes, is in connection with the fenestra
ovalis.

In the tympanic cavity of the ear of the sheep, cells, con-
taining pigment, may very generally be observed ; amongst
these, I have noticed the occurrence of numerous delicate
transparent cells, similar to those of the white substance of
the brain and spinal marrow.

ORGANS' OF THE SENSES 525

The Internal Ear or Labyrinth.

The internal ear, which is the essential portion of the
organ of hearing, consists of three parts : — the vestibule, the
semicircular canals, and the cochlea : these are cavities im-
bedded in the petrous bone, communicating with the tym-
panic cavity on the one side, by the fenestne ovalis and ro-^
tunda ; and on the other, with the internal auditory canal.
The dense bone immediately surrounding these cavities is
termed the osseous labyrinth, in contradistinction to the
membranous labyrinth contained within them. The descrip-
tion of the form, &c. of the osseous labyrinth belongs rather
to descriptive than to general or microscopic anatomy, and
therefore will not here be entered upon.

The osseous labyrinth contains a fluid which has been
called the perilymph, from its surrounding, though in the
vestibule and semicircular canals only, a hollow membranous
apparatus — the membranous labyrinth, which itself contains
a fluid, the endolymph.

The following account of the structure of the spiral lamina ;
of the cochlea ; the cochlear muscle ; the cochlear nerves ;
the membranous labyrinth; the vestibular and auditory
nerves, is copied from the " Physiological Anatomy."

Of the Structure of the Spiral Lamina of the Cochlea. —
" We shall term the two surfaces of this lamina, tympanic and
vestibular, as they regard, respectively, the tympanic or ves-
tibular scala. The osseous portion of the spiral lamina ex-
tends more than half way from the modiolus towards the
outer wall, and is perforated, as already described, by a series
of plexiform canals, for the transmission of the cochlear
nerves ; these canals, taken as a whole, lie close to the lower
or tympanic surface, and open at or near the margin of this
zone. The vestibular surface of the osseous zone presents, in
about the outer fifth of its extent, a remarkable covering,
more resembling the texture of cartilage than anything else,
but having a peculiar arrangement, quite unlike any other
with which we are acquainted. Being uncertain respecting
the office of this structure, we shall term it the denticulate

TT 2

526 THE SOLIDS.

lamina (Plate LXIX. Jig. 3.), from a beautiful series of
teeth, forming its outer margin, which project far into the
vestibular scala, and, in the first coil, terminate almost on a
level with the margin of the osseous zone, but more within
this margin towards the apex of the cochlea. They thus con-
stitute a kind of second margin to the osseous zone, on the
vestibular side of the true margin, and having a groove
beneath them, which runs along the whole lamina spiralis, in
the vestibular scala, immediately above the true margin of
the osseous zone. The intervals between the teeth, are to be
seen on their upper surface, on their free edge, and also
within this groove, so that the teeth are wedge-shaped, and
their upper and under surfaces, traced from the free edge,
recede. The free projecting part, or teeth of the denticulate
lamina, form less than a fourth of its entire breadth, and in
the remainder of its extent, it appears to rest on the osseous
zone ; seen from above, after the osseous zone has been ren-
dered more transparent by weak hydrochloric acid, rows of
clear lines may be traced from the teeth at the convex edge,
towards the opposite or concave edge of the lamina. These
lines appear to be a structure resembling that of the teeth
themselves, and they are separated from one another by row8
of clear, highly refracting granules, which render the inter-
vals very distinct. These intervals are more or less sinuous
and irregularly branched.

" The denticulate lamina, thus placed on the vestibular
surface of the osseous zone, is above, and at some distance
from the plexus of the cochlear nerves, which lies near its
tympanic surface. The vestibular surface of the osseous zone,
including the denticulate lamina, is convex, rising from the
free series of teeth towards the modiolus.

" In the groove already mentioned, there is a series of elon-
gated bodies, not unlike columnar epithelium, in which the
nuclei are very faint.

" These bodies are thick and cubical at one end, and taper
much towards the other. They are united in a row, and it
is possible they may have some analogy to the club-shaped
bodies of Jacob's membrane. We can assign them no use.

ORGANS OF THE SENSES. 527

" Continuous with the thin margin of the osseous zone is
the membranous zone. (Plate LXIX.^. 4.) This is a trans-
parent glassy lamina, having some resemblance to the elastic
laminas of the cornea, and the capsule of the lens. A narrow
belt of it, next the osseous zone, is smooth, and exhibits no
internal structure, while, in the rest of its width, it is marked
by a number of very minute straight lines, radiating out-
wards from the side of the modiolus. These lines are very
delicate at their commencement, become more strongly
marked in the middle, and are, again, fainter ere they cease,
which they do at a curved line on the opposite side. Beyond
this, the membranous zone is, again, clear and homogeneous,
and receives the insertion of the cochlearis muscle. The
inner clear belt of the membranous zone is little affected by
acids : it seems hard and brittle. The middle or pectinate
portion is more flexible, and tears in the direction of the lines.
The outer clear belt is swollen, and partially destroyed by the
action of acetic acid. Along the inner clear belt, and on its
tympanic surface, runs a single, sometimes branched vessel,
which would be most correctly called a capacious capillary,
as it resembles the capillaries in the texture of its wall, but
exceeds them in size. It is the only vessel supplied to the
membranous zone, and seems to be thus regularly placed,
that it may not mar the perfection of the part as a recipient
and propagator of sonorous vibrations.

Of the Cochlearis Muscle. — "At its outer or convex
margin, the membranous zone is connected to the outer wall
by a semitransparent structure. This gelatinous-looking
tissue was observed by Breschet, and is, indeed, very obvious
on opening the cochlea ; but we are not aware of any one
having hinted at what we regard to be its real nature. The
outer wall of the cochlea presents a groove, ascending the
entire coil, opposite the osseous zone of the lamina spiralis,
and formed principally by a rim of bone, which, in section,
looks like a spur, projecting from the tympanic margin of the
groove, the opposite margin being very slightly or not at all
marked. This groove diminishes in size towards the apex
of the cochlea. It gives attachment to the structure in

T T .3

528 THE SOLIDS.

question, by means of a firm dense film of tissue, having a
fibrous character, and the fibres of which run lengthwise in
the groove, and are intimately united to it, especially along
the projecting rim. From this cochlear ligament, the coch-
learis muscle passes to the margin of the membranous zone,
filling the groove and projecting into the canal, so as to assist
in dividing the tympanic and vestibular scalae from one
another, and thus forming, in fact, the most external or the
muscular zone of the spiral laminae. Thus the cochlear
muscle is broad at its origin from the groove of bone, and
slopes above and below to the thin margin in which it termi-
nates, so that its section is triangular, and it presents three
surfaces, one towards the groove of bone, and one to each
of the scala3. The surface towards the vestibular scala is
much wider than that towards the tympanic scala, and pre-
sents, in a band running parallel to and at a short distance
from the margin of the membranous zone, a series of arched
vertical pillars with intervening recesses, much resembling
the arrangement of the musculi pectinati of the heart. (Plate
LXIX. Jig. 5.) These lead to, and terminate in, the outer
clear belt of the membranous zone, which forms a kind of
tendon to the muscle. This entire arrangement is almost
sufficient of itself to determine the muscular nature of the
structure. If its fibres were of the striped variety, no doubt
would remain ; but its mass, evidently fibrous, is loaded with
nuclei, and filled with capillaries, following the direction of
the fibres, and in almost all respects it has the closest simi-
larity to the ciliary muscle of the eye.

" The capillaries of the ciliary muscle are derived from
vessels meandering over the walls of the scala before en-
tering it, and those from above and below do not anastomose
across the line of attachment of the membranous zone ; thus
indicating that the continuation of this zone enters as a plane
of tendon into the interior of the muscle, dividing it into two
parts, and receiving the fibres in succession.

" The scalar of the cochlea are lined with a nucleated
membrane, or epithelium, which is very delicate and easily
detached, usually more easily seen in the vestibular than in

ORGANS OP THE SENSES. 529

the tympanic scala, and in many animals containing scat-
tered pigment.

Of the Cochlear Nerves. — " These enter from the internal
auditory meatus through the spirally • arranged orifices at the
base of the modiolus, and turn over in succession into the
canals hollowed in the osseous zone of the spiral lamina, close
to its tympanic surface. In this distribution the nervous
bundles subdivide and reunite again and again, forming a
plexus with elongated meshes, the general radiating arrange-
ment of which may be readily seen through the substance of
the bone when it has been steeped in diluted hydrochloric
acid. (Plate LXIX.jfy. 6.) Towards the border of the
osseous zone, the bundles of the plexus are smaller and more
closely set, so as at length almost to form a thin uniform layer
of nervous tubules. Beyond the border, and partially on or
in the inner transparent belt of the membranous zone, these
tubules arrange themselves more or less evidently into small
sets, which advance a short distance and then terminate much
on the same level. These terminal sets of tubules are cone-
shaped, coming to a kind of point ere they cease. The white
substance of Schwann exists in them throughout, but is
thrown into varicosities and broken with extreme facility, and
they are interspersed with nuclei, so that it is very difficult
to discover the precise disposition of the individual tubules.
They seem to cease one after another, thus causing the set
to taper; and at least it appears certain that evidence of
loopings such as have been described by some, is wanting.
In the cochlea of the bird, however, we have seen at one
end a plexiform arrangement of nucleated fibres ending in
loops ; but this is a peculiar structure.

" The capillaries of the osseous zone are most abundant on
the tympanic scala, in connection with the nerves now men-
tioned, and form loops near the margin, with here and there
an inosculation with the large marginal capillary already
mentioned.

Of the Membranous Labyrinth. — " This has the same
general shape as the bony cavities in which it lies, but is
considerably smaller, so that the perilymph intervenes in

T T 4

530 THE SOLIDS.

some quantity, except where the nerves passing to it con-
fine it in close contact with the osseous wall. Its vestibular
portion consists of two sacs, viz. a principal one of trans-
versely oval figure and compressed laterally, called the utri-
culus, or common sinus, occupying the upper and back part
of the cavity, in contact with the fovea semi-elliptica, and
beneath this a smaller and more globular one, the sacculus,
lying in the fovea hemisph erica, near the orifice of the ves-
tibular scala of the cochlea, and probably communicating
with the utriculus.

" The membranous semicircular canals have the same names,
shape, and arrangement as the osseous canals which enclose
them, but are only a third of the diameter of the latter. As
the osseous canals open into , the vestibule, so the membranous
ones open at both ends into the utriculus, there being,
however, a constricted neck between this sac and the ampul-
lated extremity of each canal. The auditory nerve sends
branches to the utriculus, to the sacculus, and to the am-
pulla of each membranous canal. These nerves enter the
vestibule by the minute apertures before described, and tie
down, as it were, both the utriculus and sacculus to the
osseous wall at those points, the membrane being much
thicker and more rigid at those parts. The branches to the
ampulla of the superior vertical and the horizontal semi-
circular canals enter the vestibule with the utricular nerve,
and then cross to their destinations, while that to the am-
pulla of the posterior vertical canal traverses the posterior
wall of the cavity and opens directly into the ampulla.

" The wall of the membranous labyrinth is translucent,
flexible, and tough. When withdrawn from its bed and ex-
amined, it appears to present three coats, an outer, middle,
and internal. The outer is loose, easily detached, somewhat
flocculent, and contains more or less colouring matter disposed
in irregular cells exactly resembling those figured at page 22.,
from the outer surface of the choroid coat of the eye. We
have not found a true epithelium on this surface. The
middle is the proper coat, and seems more allied to cartilage
than any other tissue ; its limits are well marked, it is trans-

ORGANS OF THE SENSES. 531

parent, and exhibits in parts a longitudinal fibrillation ; treated
with acetic acid, it presents numerous corpuscles or cell nuclei.
Where it is thinnest it has a near resemblance to the hyaloid
membrane of the eye. The internal coat is composed of nu-
cleated particles, closely opposed, and but slightly adherent ;
the nuclei are often saucer-shaped, and when seen edgeways
have the uncommon appearance of a crescent. They easily
become detached and fall into the endolymph. Minute
arteries and veins, derived chiefly from a branch of the ba-
sillar accompanying the auditory nerve, enter the vestibule
from the internal meatus, and ramify on the exterior of the
membranous labyrinth, apparently bathed in the perilymph.
A beautiful network of capillaries, forcibly reminding the
observer of that belonging to the retina, is spread out on the
outer surface and in the substance of the proper coat. These
vessels have the simple homogeneous wall interspersed here
and there with cell nuclei, that characterises the capillary
channels in many other situations. There is an abundant
network of capillaries in the interior of the utriculus and
sacculus, about the terminal distribution of the nerves, which
evinces the activity of the functions of these parts.

" The membranous labyrinth, or its simple representative
the auditory sac, contains in all animals either solid or pulve-
rulent calcareous matter in connection with the termination of
the vestibular nerves. This has been called by Breschet
otolith or earstone, when solid, as in the osseous fishes, and
otoconia or ear-powder, when in the form of minute crys-
talline grains, as in Mammalia, birds, and reptiles ; but the
former term may be conveniently employed to designate both
varieties. In the Mammalia, including man, it is found ac-
cumulated in small masses about the termination of the nerves,
both in the utriculus and sacculus, and we have found it also
sparingly scattered in the cells lining the ampulla? and semi-
circular canals. In the vestibular sacs it appears to be en-
tangled in a mesh of very delicate branched fibrous tissue, in
connection with the wall, and it is most probably held in place
by cells within which, according to Krieger *, its particles

* De Otolithis. Bcrol, 1840.

532 THE SOLIDS.

are deposited. It has a regular arrangement, and is not free
to change its place in the endolyraph. Otolithes consist
always of carbonate of lime.

Of the Vestibular Nerves. — t( In consequence of the thick-
ness of the wall of the membranous labyrinth where the
nerves enter, and the presence there of the calcareous and
fibrous matter, it is not easy to ascertain with certainty the
precise manner in which the nerves terminate. In the utri-
cule and saccule, they appear to spread out from one another
as they enter, and then to pass, some to mingle with the
calcareous powder, others to radiate for a small extent on the
inner surface of the wall of the cavity, where they come into
connection with a layer of dark and closely set nucleated
cells, and presently loose their white substance. We have
seen a fibrous film on the inner surface of these parts which
we are disposed to consider as formed, like the inner surface
of the retina, by the union of the axis-cylinders of the nerve
tubes, but confirmatory observations are required. Those
that traverse the calcareous clusters have appeared to us, in
the most lucid views we have succeeded in obtaining, to
terminate by free, pointed extremities, without losing their
white substance. In the frog this has been evident enough.
(t The nervous twigs belonging to the semicircular canals
do not seem to advance beyond the ampullae, in which they
have a remarkable distribution, entering them, as Steifen-
sand has well shown, by a transverse or forked groove, on
their concave side, and which reaches about a third round.
Within this, the nerve projects so as to form a sort of trans-
verse bulge within the ampulla. Their precise termination
c"an be best seen in the osseous fishes, and has been de-
scribed by Wagner to be loop-like. We believe we have
seen this mode of termination, though certainly never so
plainly as the figure given by this excellent author would
indicate ; and we may add that we have found free extrem-
ities to the nerve tubes, as well as loopings, in the ampulla
of the cod. The difficulty in these cases of ascertaining the
exact truth arises from the curves formed by the nerve tubes

ORGANS OF THE SENSES. 533

in proceeding to their destination, and which are liable to be
mistaken for terminal loopings.

Of the Auditory Nerves. — '.' At the bottom of the meatus,
the portio mollis divides into two branches, one to the ves-
tibule and semicircular canals, the other to the cochlea.

" The vestibular nerve divides into three branches ; — the
largest is uppermost, and penetrates the depression which
is immediately behind the orifice of the aqueduct of Fallo-
pius to be distributed to the utriculus, and to the ampulla? of
the superior vertical and horizontal semicircular canals. The
second branch of the vestibular nerve is distributed to the
sacculus ; and the third to the posterior vertical semicircular
canal.

" The cochlear nerve penetrates the funnel-shaped de-
pression at the bottom of the auditory canal, and proceeds
from it through the numerous foramina, by which its wall is
pierced in a spiral manner, to the lamina spiralis of the
cochlea.

" The mode of distribution of these nerves has been already
described.

" The labyrinth receives nerves from no other source but
the portio mollis, unless we suppose the portio intermedia to
consist of filaments from the facial which accompany the
ramifications of that nerve into that part of the ear."

534

APPENDIX.

Pituitary Gland.

THE pituitary body, inasmuch as it presents the usual cha-
racteristics of glandular structures, would be more accurately
denominated the pituitary gland, a term which conveys its
real nature.

The pituitary gland, in the absence of an excretory duct—
unless indeed the infundibular process attached to it is to
be considered as such — would appear to be allied to the
vascular glands, while in some other respects it resembles
the ganglia of the sympathetic, which also are glandular
organs.

It consists of two lobes, an anterior and a posterior, which
differ from each other in size, colour, and consistence ; the
former is considerably the larger of the two, is of a yellowish
grey colour, and of much firmness and density ; while the
latter is grey and soft, and scarcely differs in consistence
from the grey matter of the cerebrum.

As the two lobes differ in colour and consistence, so are
they somewhat different in structure also; the anterior or
denser lobe is made up of numerous granular cells, very
various in form and size, and many of which are in some
cases of very considerable dimensions ; these cells lie in
meshes of fibrous tissue which separate and parcel them out,
each of the larger cells occupying separately an entire mesh.
(Plate LXIX. fig. 8.) The posterior lobe differs from the
anterior in the smaller size of its cells, and the less amount
of fibrous tissue which enters into its composition.

The pituitary gland is connected with the brain by means
of the infundibulum, the small extremity of which is attached

APFENDIX. 535

to the superior concave surface of the gland, and is united
principally to the posterior lobe, which it also resembles
in structure, containing very many grandular cells in its
parieties.

This gland resembles a ganglion of the sympathetic in the
large size of its cells, and in the arrangement of its fibrous
constituent ; but differs from it in the irregular form of the
cells, and in the absence, so far as has been yet ascertained,
of tubular nerve fibres.

Pineal Gland.

Notwithstanding the interest which exists in the minds of
most persons in reference to this body, and which has arisen
in consequence of the strange physiological speculations of
which it has been the subject, its structure yet does not
appear to have been examined with that amount of care
which has now been bestowed upon most of the other organs
which enter into the constitution of the human fabric ; not,
however, that its organization is uninteresting or difficult to
be understood, for this, while it is complex and singular, yet
admits of easy determination.

The chief bulk of the pineal gland is made up of innu-
merable minute granular cells which, when carefully ex-
amined in a perfectly fresh subject, are seen to be of the
caudate form, the rays of the cells being exceedingly delicate
and slender, and apt, therefore, to be entirely overlooked.

Imbedded in this cellular matrix, and, for the most part,
collected in the centre of the organ, there may be noticed
numerous particles of stony hardness of various sizes, and
mostly of a rounded form, and the larger of which are plainly
visible to the naked eye. Of these bodies, I have never en-
countered any satisfactory description; they are not, as
generally considered, mere inorganic and earthy particles,
but structures of a definite and complex organization, con-
stituting an essential element in the composition of the pineal
gland. When viewed with the half or quarter inch object-
glass, the larger of these bear much resemblance to masses of

536 APPENDIX.-

fat, each being composed of numerous distinct and aggre-
gated lesser pieces or particles which reflect light strongly,
and it is in this circumstance as well as in their large size,
that the resemblance borne by these bodies to masses of fat
consists. (Plate LXIX. fig. 7.)

In the natural condition, these bodies are hard and brittle ;
after, however, the application of dilute nitric acid, they
become soft, the earthy matter being dissolved away, and
nothing remaining but their animal constituent ; this, if the
acid employed has not been too strong, still retains, to a
great extent, the size, form, and appearance of these bodies,
previous to its action, and will now readily be seen to exhibit
a cellular structure, a cell corresponding to each of the bright
constituent pieces above described. If, however, the acid
employed be somewhat stronger, these bodies undergo a
singular change in form and appearance, the cellated spaces
become almost lost to view, and these compound structures
assume the characters of large and spherical cells exhibiting
numerous concentric lamellae. The earthy matter, then, is
contained in these cells or cellated spaces ; the acid dissolves
this away, and the entire body becomes so soft, as to admit
readily of being torn to pieces with needles ; in this state, its
structure may be easily determined, and is seen to consist of
membranous elastic tissue.

These bodies originate in exceedingly small and bright
circular discs, which when seen with the quarter inch object
glass, are less in size than the head of a pin ; in these appear
first, one, and, afterwards, other divisions, indicating the
compound and cellular character, which they ultimately more
completely exhibit.

The earthy matter entering into their composition, consists
of phosphate of lime, a small portion of phosphate of mag-
nesia, and a trace of carbonate of lime.

Minute sandy particles have been described connected with
the choroid plexuses, and that portion of the velum inter-
positum which invests the pineal gland ; whether these
bodies are of the same nature as those occurring in the gland

APPENDIX. 537

itself, I am unable to say, not having myself detected them
in either of the above situations.

These bodies, which are almost peculiar to the human
subject, are stated not to occur in the pineal gland, until
after the age of seven years.

In addition to the above described essential elements of
every fully formed human pineal gland, I encountered on one
occasion two large round cells or bodies containing dark
nuclei of a compound character ; these appeared to be some
modification of the sabulous bodies already described.

The pineal gland is copiously supplied with blood vessels,
is traversed sparingly with delicate nerve tubules, and con-
tains a small quantity of an exceedingly slender form of
fibrous tissue, which possibly proceeds from the caudate cells
already noticed.

The Pia Mater.

The pia mater, the vascular membrane of the brain, is
composed of fibrous tissue and blood-vessels ; over the surface
of the brain and its convolutions, this membrane is delicate
and highly vascular, while over the spinal marrow, it is thicker
and less freely supplied with vessels.

In the ventricles, this membrane forms the choroid plexuses
and velurn interpositum ; in the former, it is thrown up into
numerous processes or villi, each of which is furnished with a
large looped blood-vessel, and its outer surface, like the villi
of the intestines, is clad with a very evident epithelium.
(Plate LXIX. fig. 9.)

This epithelium, according to many observers, is of the
ciliated kind; the cells composing it, are polygonal, some-
what flattened, and as Henle * long since noticed, furnished
at their angles with spinous processes ; these are only to be
seen in perfectly fresh subjects, and it is probable that in
some cases, they have been mistaken for cilia ; not, however,
since the fact has been attested by several witnesses, that I

* Anat. Gen. t. i. p. 233.

538 APPENDIX.

would deny the existence of ciliary processes on the cells of
this epithelium.

The Pacchionian Glands.

The Pacchionian Glands are found among the vessels of
the pia mater on the edges of the cerebral hemispheres, and
are described as granulations composed of an albuminous
material ; they push before them the arachnoid membrane,
project into the longitudinal sinus, and, in some cases, even
occasion absorption of the parietal bones, lying imbedded in
little pits or recesses. They are stated not to occur in early
life, and they are frequently absent in the adult.

I have encountered on the surface of different portions of
the pia mater, usually near to the sulci of the convolutions,
little masses or bodies of two forms, apparently very distinct ;
in the first, these were opaque and whitish, and consisted of
a capsule of fibrous tissue, enclosing a number of minute
granular cells ; in the second, the masses appeared to lie free
amongst the vessels of the pia mater, and each broke up
readily on being touched into several other smaller granula-
tions of the same character : these examined with the micro-
scope, were seen to be made up of numerous dark looking
bodies very irregular in form and size, and which appeared
to be of a fatty nature.

Observations on the Development of the Fat Vesicle*

f( WHEN the difficulty of determining the exact structure of
the fat vesicle is considered, — a difficulty arising from the
extreme tenuity of its cell- wall, and the opacity of its con-
tents, — it is scarcely surprising that we should yet be with-
out any consistent account of the modes of development and
growth of the fat vesicle.

* By the Author. " Lancet," January 20th, 1849.

APPENDIX. 539

" This hiatus in the structural history of that peculiar
animal tissue, fat, the present brief remarks are intended in
some measure to fill up.

" When the little fatty masses which are met with so abun-
dantly in the neck, in the neighbourhood of the thyroid and
thymus glands, as also in some other situations in a foetus
nearly or quite arrived at maturity, are examined, it will be
observed, by the use of a lens only, that these masses are
each composed of a number of distinct and opaque bodies of
various sizes, presenting a smooth outline, having a more or
less rounded or oval form, and held loosely together by fibro-
cellular tissue, the extension of which forms the envelope
which invests each of these bodies. It will also be further
noticed, that each mass of fat is supplied with one or more
blood-vessels, and that these break up into numerous lesser
branches, one of which goes to each of the previously-de-
scribed bodies, being conveyed to it by the connecting fibrous
tissue ; and that, having reached this body, it undergoes a
further subdivision, the branches extending over its entire
surface.

" In continuation of these observations, it will be remarked,
that each of these peculiar bodies bears a close resemblance,
in its general aspect, to a lobe of a sebaceous gland — a
resemblance, which, as will be seen almost immediately, ex-
tends even to its internal structure.

" If a number of these bodies be torn into fragments with fine
needles, and be examined with a half or quarter-inch object-
glass, it will be observed that the cavities of some of them are
filled with cells of a large size, and which again are occupied
with numerous globules of various dimensions, presenting many
of the characters of oil globules, but being of greater consist-
ence. ( Plate L XI X.^/?^. 10.) These cells, save by their some-
what larger size, it is impossible to distinguish from the perfect
cells of -sebaceous glands ; so complete indeed is this resem-
blance, that at first sight I did not hesitate to regard them as
belonging to some sebaceous gland, and which I was much
astonished to encounter in such a situation. Others of these
peculiar bodies, which may be termed f fat cysts,' contain a

u u

540 APPENDIX.

mixture, in variable proportions, of these compound cells and
of free globules, which, however, it is to be observed, are
generally of larger size than those contained within the com-
pound or parent cells. Lastly, others of these bodies enclose
no compound cells, but are filled with globules of still larger
size. (Plate LXIX. fig. 11.)

" Now the curious part of this history is, that it is these
globules which go on increasing in size, and, bursting the
envelopes which contain them, ultimately become what are
ordinarily regarded as the true fat vesicles.

" In the article Fat, in an early number of the s Microscopic
Anatomy,' I noticed the fact, that the fat vesicles of children
are not so large as those of the adult ; this fact it then ap-
peared to me had an evident relation to the growth of the
fat vesicle, and it suggested the idea that the fat corpuscle
was of very slow growth, not attaining its full dimensions
until near the adult age ; and that it was permanent in its
character, enduring throughout life. This idea gathers in-
creased weight, and, indeed its correctness is rendered almost
certain, by the additional observations just cited on the deve-
lopment and growth of the fat vesicle.

" It would appear, therefore, taking into consideration all
the foregoing particulars, that the principal development of
fat vesicles takes place in the advanced foetus, and in the
early years of life (for I now remember having met with e fat
cysts' in the great omentum of children of five and six years
of age, although at the time of observing them I did not know
their nature and meaning), that what are usually regarded as
the true fat vesicles or cells, are first contained in parent
cells, and lastly, that they are slow in their growth, and per-
sistent throughout life.

" I infer also further, from the foregoing facts, that the
ordinary fat vesicles are incapable of acting as parent cells and
of reproducing their like ; an inference which might be fairly
entertained on other grounds — viz., the difficulty, not to
say impossibility, of detecting nuclei in them, and the ab-
sence of those granules amongst their contents which are so
characteristic of true cells, and which there is so much reason

APPENDIX. 541

to believe are the real germs of the future generations of
cells.

" From comparative observations it would appear that the
development and growth of fat proceed at different rates in
different localities of the same body, it being more advanced
in one situation than in another ; and also in the same parts
in different children of the same age ; so that an exactly
similar condition of things to that which I have described as
existing in the masses of fat which occur in the region of the
neck in the mature foetus, must not in all cases be looked
for.

" The structural resemblance which I have shown to exist
between fat cells in an early condition of their development,
and the cells of sebaceous glands is most interesting, the
latter appearing to be, in fact, simply fat in a rudimentary
and imperfect state of its development."

On the Structure and Formation of the Nails.

Since the publication of the article contained in this work
on the structure of nail, some further observations by
Mr. Rainey, on the same subject, have appeared ; the more
important of these are contained in the following ex-
tracts * : —

" The object of this paper is to show that the nails consist of at least
two distinct structures : one proper to them, the horny structure, and
the other the cuticular one ; and also, that their matrix possesses one set
of vessels expressly for the secretion of the horny part of the nail, and
another set for the formation of the cuticular portion ; and that besides
these, there are other vessels differing in their characters and arrange-
ment from the preceding, and probably intended to furnish a material,
intermediate in some of its properties between horn and cuticle ; and
destined to blend these together, and thus to preserve their union
during the growth and protrusion of the nails. However far this idea
may be correct, the anatomical fact of there being these three different
arrangements of vessels is indisputable.

* On the Structure and Formation of the Nails of the Fingers and
Toes. By G. Rainey, Esq., M.R.C.L. Transactions of the Microscopical
Society, March, 1849.

u u 2

542 APPENDIX.

Structure of the Nails.

" If a thin vertical section be made lengthways through a finger-nail
from its posterior to its anterior or free margin, the external or dorsal
surface of that portion of it which was lodged in the groove between
the matrix and the semilunar fold of skin projecting from the dorsum of
the finger, is seen covered by a thin layer of cuticle, which extends
backwards as far as its posterior border, which is generally jagged and
uneven, and forwards upon its dorsum. This portion of cuticle is im-
mediately continuous with that overhanging the root of the nail, and
although it is not inseparably blended with its horny substance, yet it is
sufficiently adherent to be carried forward with it during its growth and
to remain intimately attached to its dorsal surface until it is worn off by
friction or some other mechanical cause. The palmer surface, near to its
free border, is also- seen covered by cuticle, which in like manner divides
into two parts, the one becoming continuous with the cuticle covering
the end of the finger ; the other passing backwards along the palmer
surface of the nail as far as the lunula, where it imperceptibly terminates.
This portion of cuticle gradually diminishes in thickness as it extends
backwards, and is more intimately connected with the horny part of the
nail than was the cuticle on its dorsal surface. Between these layers of
cuticle the proper or horny matter of the nail can be distinguished, pre-
senting fine, nearly parallel, and generally semi- elliptical lines, with their
concavity looking in different directions in different parts of the same
section, and also a multitude of darkish-looking corpuscles, when viewed
by transmitted light, of various forms and sizes. These compose the
substance of the horn of the nail, and the lines are the cut edges of the
lamina? of which it is made up. The horny part of the nail does not
increase in thickness after it has extended beyond the lunula, the ap-
parent increase of the nail anterior to this point being derived from the
cuticle formed upon the anterior part of the matrix.

The Matrix of the NaiL

" A mere inspection, even in the living subject, of the parts situated
beneath the nail, is, in consequence of its transparency, sufficient to give
a general idea of the relative vascularity of the various parts of its
matrix. The upper part of the matrix is seen to present a pale, semi-
lunar space, called the lunula. The greater part of the lunula is con-
cealed by the semilunar fold of integument which projects over it ; but
extending a little below this fold the lower portion of the lunula is
visible, presenting a curved border, with its convexity looking down-
wards^. Immediately below the lunula, and circumscribing its inferior

APPENDIX. 543

limit, the matrix has a reddish colour, which gradually becomes fainter
towards the free margin of the nail, but which deepens considerably
where the nail becomes detached from the integument.

" When the matrix is fully injected and the nail removed, the part
corresponding to the lunula presents several rows of convoluted capil-
laries : the individual convolutions have different degrees of complexity,
from a simple loop a little twisted round itself, to a complex tuft of
vessels. These rows have their direction from above to below, they are
all slightly curved, being concave towards the median line of each nail,
and the most external ones are nearly parallel with its lateral margins.
These, being the vessels which secrete the horny part of the nail, may
be called the horn-vessels. Superiorly these vessels are separated from
the rich plexus on the fold of integument which overhangs the nail, by
a fibrous and almost non-vascular groove, in which the free border of the
nail was lodged, and where the cuticle covering its root terminates. A
few vessels, however, pass across this groove from the horn- vessels to the
plexus just mentioned. Inferiorly the horn-vessels, communicate with
quite a different arrangement of capillaries, which run in a more
straight course, and are much more crowded together than the horn-
vessels. These vessels run nearly parallel with one another, in a direc-
tion from behind forwards, and being very near together, render this the
most vascular part of the matrix ; and produce that redness immediately
below the lunula upon which the form and degree of distinctness of its
lower border is dependent. Just below these vessels the surface of the
matrix begins to be raised into numerous plications or folds, passing
directly forwards, and increasing in depth as they approach the free
extremity of the nail, where they become continuous with the raised
lines observable on the ends of the fingers. These plicae consist each of
a fold of basement membrane, enclosing a series of loops of vessels. At
first these loops are small and simple, but they become larger and more
complex, as they advance towards the end of the finger, where they arc
continued from the ridges of the matrix of the nail into those of the
skin of the finger, in which they are generally very complex. When the
nails are in situ, these ridges are received into corresponding grooves in
their inferior surface. Near the part of the matrix where the plica?
commence, several distinct circular or oval openings are sometimes seen
passing for some depth beyond the surface, and appearing like follicles
or lacuna?. These are frequently closed by the opposition of the adja-
cent plica?, and thus their presence is rendered doubtful, but they can be
seen very distinctly either when some of the material which they contain
has been recently removed, or still remains within them in the form of
whitish, globular masses. The situation of these lacunae, where the open-
ings themselves are not apparent, can be distinguished by the plexus of
capillaries in their vicinity, in the areola3 of which their openings are
situated."

u u 3

544 APPENDIX,

On the Ganglionic Character of the Arachnoid Membrane.

The following extracts contain the more important por-
tions of Mr. Bainey's observations " On the Ganglionic Cha-
racter of the Arachnoid Membrane of the Brain and Spinal
Marrow " * : —

" The first idea which suggested to me the resemblance of the arach-
noid to the sympathetic, was from the examination of a piece of the
former taken from the inferior and lateral part of the medulla oblongata,
when I observed, at the meeting of two of the chords situated between
the arachnoid and pia mater (called by Mengendie " Tussu Cellulo-vas-
culaire sub-Arachnoide "), a triangular body of the form and general
appearance of a ganglion, very similar to such as I had seen in small
animals.

" This resemblance appeared more striking on observing a branch going
from the chord connected with this body, to the arachnoid membrane,
along which it ran for a considerable distance, dividing and sub- dividing
in its course, in the manner of a nerve ; the successive sub-divisions be-
coming more and more minute, and at the same time interlacing and
enclosing small areolse filled with corpuscular matter. These corpuscles
were so blended with the ultimate filaments of this chord as to render
indistinct their exact mode of termination.

" Such was the connexion of one extremity of one of these chords.
The next point to be determined was the structure to which the other
extremity of the same chord had been attached. As, in this case, it had
been separated from its connexion, this could only be ascertained by
examining similar chords in other portions of membrane. This examin-
ation being made, I found that the end in question terminated either on
an artery or on a cerebro-spinal nerve. In the former case a chord, as
soon as it comes in contact with an artery, divides into branches which
ramify upon it, and run along its external coat, just as, to all appear-
ance, the branches of the solar plexus do on the small arteries supplying
the viscera in the abdomen. If the cerebral artery be rather large, and
situated between the arachnoid and pia mater, some of the branches
going from a chord form upon it a plexus, and others proceed on-
wards to the vessels of the pia mater.

" In some instances a chord passes from an artery to the arachnoid
without dividing in its course, as just described ; but more frequently on
approaching the latter it sends off three or four large branches, which
pass to different parts of the membrane, and ramify in it, as before ex-
plained ; however, sometimes one of these branches either itself expands
into a large dense plexus, or joins other branches to form one, from

* Medico-Chirurgical Transactions, 1846.

APPENDIX. 545

which plexus two, three, or more chords pass into the substance of the
arachnoid. The shape of these plexuses is either square or triangular,
according to the number of branches which join them, and the number
they give off. Besides consisting of interlacing fibres, they also contain
corpuscular matter.

" The arachnoidal extremity of some of the chords connecting the
vessels with the arachnoid of the cauda equina expands, close to the
membrane, into a large oblong and rather oval bulb, the axis of which
is occupied by a continuation of the chord, extremely convoluted and
bent upon itself; whilst, inferiorly, its fibres are blended with those of
the membrane.

" The chords which pass from the vessels of the pia mater, at the
upper portion of the brain, to the arachnoid, terminate in the latter by
fibres having a stellate arrangement. There are also some large triangular
plexuses like those at the base of the brain, from which branches descend
between the convolutions to the vessels within the sulci.

" In the lower animals, as in the sheep, in which the cerebral convolu-
tions are small, the stellate fibres are the best seen. They can even be
distinguished by the naked eye, appearing like minute opaque points. At
their centre, the fibres of which they are composed, seem to be blended
into an irregular confused mass, from which other fibres radiate, and lose
themselves in the cerebral surface of the arachnoid. Some fibres go from
one stellate body to another, and others can be traced into the coats of
the vessels : these latter are by no means numerous. Branches also de-
scend (still having somewhat the stellate disposition) between the con-
volutions to the deep-seated vessels; these filaments are much more
numerous upon some vessels than upon others, and they do not appear to
extend so far as the capillaries, no fibres of any kind being visible upon
this system of vessels.

" It appears, from what has been stated, that the disposition of the
ramifying filaments of the arachnoidal chords, and the form and size of
the gangliform plexuses connected with them, bear some proportion to
the number and size of the vessels in their vicinity. Hence, about the
base of the brain, where the branches of the arteries are large, the
plexuses are also large, and of an irregular shape, whilst on its upper
surface, where the vessels are comparatively small, and more equal in
size, and have a more uniform distribution, the plexuses also are smaller,
more numerous, and more regular in their shape and volume.

" Besides the plexuses situated in the course of .the chords of the
arachnoid, there are others which are more intimately connected with its
cerebral surface, and which, in some situations, appear to compose the
entire thickness of the membrane.

" In these plexuses, the filaments interlace very much in the same
manner as the nerves do in the plexuses of the cerebro-spinal and sym-
pathetic systems. A chord, for instance, when traced into one of them,
will be observed to break up into its component filaments, the adjoining

u u 4

546 APPENDIX.

bundles of which interlace, yielding to one another one or more bundles,
and the chords which emerge from the plexuses deriving their component
filaments from different bundles : these bundles, and their component
threads, during their interlacing, will be seen to preserve their indi-
viduality.

" When a chord going from the arachnoid, terminates on a cerebral
nerve, it divides in the same manner as an artery, some filaments ascend-
ing and others descending, along with the nerve tubules. In some in-
stances this extremity terminates in a sort of membranous expansion,
which encloses several nerve tubules."

Mr. Rainey, in the next place, enters upon the consideration of the
nature of the above-described apparatus of ramifying chords and
plexuses, and arrives at the conclusion, derived from their relations and
intimate structure, that they are composed essentially of gelatinous or
sympathetic nerve filaments.

" In the chords of the arachnoid (he writes) I could distinguish three
different kinds of filaments, all which exist in the branches of the sym-
pathetic.

" One species, generally considered the most characteristic, is the
nuclear fibre described by Henle ; it is a flat, clear fibre, with oval, nearly
equidistant nuclei, and each having its long axis corresponding to that of
the fibre. I have found these fibres in the arachnoid, but they are very
rare. I have seen such going from the arachnoid to the coat of the in-
ternal carotid, the trunks being blended with the membrane, and the
branches connected with the artery. I also found, that as the fibres
branch off from these 'trunks, and intermix with others, they lost their
nuclei, became more pale and clear, and differed in no respect whatever
from the other fibres of the membrane. Besides, I have seen these
fibres in other parts of the membrane, and they exist chiefly on the ex-
terior of the larger chords. This species of fibre I have also found to be
very uncommon in the smaller branches of the nerves confessedly sym-
pathetic, especially in those most remote from the ganglia and larger
trunks. The next kind of fibre is one consisting of bundles, for the most
part rather smaller than nerve tubules, of very minute wavy filaments, in-
termixed with small particles of granular matter, having no definite form,
size, or position in respect to the filaments. Some of the chords of the
arachnoid are made up entirely of fibres of this description ; in others
they exist chiefly on their surface, being most abundant near their at-
tachment to the arachnoid, upon which they are continued. This kind
of fibre exists abundantly in all the branches of the nerves undoubt-
edly sympathetic ; and also, more or less, in those connected with the
ganglia. The third kind of fibre occurs in the form of roundish, though
sometimes flat chords, composed of extremely minute wavy filaments,
either collected or not into bundles, but apparently interwoven some-
what together, so that, generally, a filament of only an inconsiderable
length will admit of being detached mechanically from the rest, and,

APPENDIX. 547

when thus separated, its breadth is very unequal, and its contour ill-
defined. These filaments are often totally destitute of granular matter.

" This last species of fibre is very common among the chords com-
posing the plexuses of the arachnoid; it is also sometimes situated in the
centre of the larger ones, surrounded by the second species of fibre ; this
can be detached mechanically, and exhibited separately under the mi-
croscope.

" In the nerves obviously sympathetic, this kind of fibre exists in con-
siderable abundance in those branches of the solar and other plexuses
which are most remote from the ganglia.

" Thus far my observations have been confined to the structure of the
fibres of the arachnoid, and their supposed use. I will now consider the
corpuscular or ganglionic part of this membrane. Some of the plexuses
on its cerebral surface have the interstices formed by their interlacing
fibres, completely filled up with small roundish corpuscles, about the size
of blood-discs ; whilst, in others, these fibres are covered with irregularly-
oval masses of them. On this surface also, in various situations, there
are well defined round or oval bodies, having in their centre a granular
nucleus surrounded by fibrous tissue, intermixed with more or less cor-
puscular matter. Some of these bodies are connected to the fibres of the
arachnoid by a very fine thread, others are situated at the conflux of
two or more fibrous chords, and their diameter varies from that of two to
seven blood-corpuscles. They are generally solitary and not numerous ;
but as they have been present in the arachnoid of every human subject
which I have examined (a number exceeding twenty), they cannot be
regarded as accidental or adventitious. At present I cannot decide as to
their nature or office, not having seen anything which they exactly re-
semble in other parts of the body ; at any rate, they look more like small
ganglia than anything else I have seen.

" Besides these corpuscles, which, as before stated, exist on the cerebral
surface of the arachnoid, I have met with some of a very different cha-
racter, situated in its substance, though nearer to the cranial than to the
cerebral surface. The most ordinary appearance which these present,
when seen by transmitted light, is that of a section of an urinary calculus
made through its centre, appearing, like it, to be made up of concentric
layers. When viewed by reflected light, these bodies seem to be vesi-
cular, and filled with fluid, the quantity of which appears to diminish as
the number of layers increases, so that those in which the laminae have
extended as far as the centre, are almost flat. Although the most fre-
quent form of these bodies is circular, yet some are oval ; occasionally
they are connected with a fibre of the arachnoid, in such a manner as to
resemble small Pascinian corpuscles. One remarkable fact connected
with these bodies is that they occur in the arachnoid of almost every sub-
ject which I have had an opportunity of examining, and that no part of
the membrane is exempt from them ; generally they are solitary, and very
sparingly distributed ; but sometimes they are in clusters. I have found

548 APPENDIX,

them in the internal Pacchionian glands mixed with granular matter, and
the same kind of fibre as exists in most parts of the arachnoid membrane.
Their diameter varies from 75,000 to 39,800 of an inch. I have observed
on some parts of the arachnoid, in the vicinity of a cluster of these bodies,
cavities of a similar shape and size, from which the corpuscles themselves
appear to have been dislodged. From this circumstance, as well as from
the general aspect of these bodies, they seem to me either to be structures
altogether adventitious, or the result of an abnormal deposition in diseased
corpuscles. The tendency which they may be observed to have to co-
alesce when several smaller ones occur together, evident by the oblite-
ration of those portions which seem pressed against one another, and
the union of the remote segments to form a single outline enclosing an
area whose figure clearly indicates the number of corpuscles which have
united to form it, proves them to be something more than mere earthy
deposits, such as are sometimes found in the choroid plexuses, or even
than mere scrofulous tubercles. Vogel has found bodies similar to these
in the choroid plexuses ; in these, and in the pia mater, Dr. E. Harless
has also seen them, and given a very minute account of their structure
in a number of Muller's Archives, 1845. This author seems to think that
their seat is in the arteries, and that they are somewhat allied to ossifi-
cation of these structures ; but their occurrence in all parts of the arach-
noid, in some of which there are probably no vessels, is opposed to this
view."

Mr. Rainey regards the corpuscles constituting the epithelium of the
choroid plexuses as ganglionary, and details his reasons for this opinion ;
hese, h owever, cannot be admitted to be decisive on this point.

" As respects the supply of vessels and cerebro-spinal nerves to the
arachnoid, I may observe, that the arteries are few, but rather large,
almost sufficiently so to receive a small injection tube ; (I have prepar-
ations of these ;) and that cerebro-spinal nerves may be traced into its
visceral portion, and, with the microscope, their tubules can be seen run-
ning along with the arachnoid fibres, into which they appear, from the
gradual loss of their tubular contents, to degenerate."

Structure of the Striped Muscular Fibrilla.
At page 341., doubts were expressed as to the correctness
of the view entertained by Drs. Carpenter and Sharpey, in
reference to the structure of the striped muscular fibrilla,
At that period, the author had not seen any of Mr. Lealand's
preparations, on the examination of which the above-named
gentlemen founded their opinion ; he has since, however,
been favoured by Dr. Carpenter with the examination of his
own specimen, and this would certainly appear to bear out
fully their opinion of its cellular constitution.

APPENDIX. 549

Structure of the Bulb of the Hair.

Further opportunities of examination have satisfied the
author that the vesicle which he has described as forming
a portion of the bulb of the hair has no existence, and that
this rests immediately upon a compound vascular and nervous
papilla.

The Synovia! Fringes.

The synovial fringes consist of branched and elongated
threads or filaments, which taper to a point, and each of
which is supplied with one or more, according to its size,
contorted and looped blood-vessels ; these, however, do not
reach the whole length of each thread, but terminate at
one third or one half its length. It is in the termina-
tions of these filaments, according to the observations of
Mr. Rainey, that those cartilage- like bodies sometimes found
loose in the joints, especially the knee joint, are first formed.
The threads or filaments of which the synovial fringes are
constituted are of such length and so much branched, that
they might, at first sight, be mistaken for those of some con-
ferva of the genus Cladophora.

On the Anatomy of the Sudoriparous Organs.

Mr. Rainey * describes the duct of the sudoriparous glands
as consisting of two distinct portions, an epidermic and
dermic.

The epidermic portion is of a conical form, the base being
directed towards the surface, and the apex situated in the
midst of the cells which form the deep layer of the epidermis ;
it is constituted of cells which are flattened and elongated,
and the long axes of which are disposed in the direction of
the length of this portion of the duct : below, near its ter-
mination, the cells arc thicker and less flattened.

* On the Minute Anatomy of the Sudoriparous Organs. By
G. Rainey. Royal Med. and Chirur. Society. See "Lancet," 1849.

550 APPENDIX.

The dermic portion of the duct is also of a somewhat co-
nical shape, its base being in like manner directed upwards,
and its parieties being continuous with the basement mem-
brane of the dermis ; this portion, therefore, is of a totally
different structure from the former; it is described by
Mr. Rainey as being lined by a layer of epidermic scales,
which get gradually indistinct towards the gland, and its
upper or expanded part as receiving the termination of the
epidermic division of the duct.

This description of the duct of the sudoriparous gland, so
far as I have been able to follow it, would appear to be in
its main particular correct, it consisting, as stated, of two
portions, an epidermic and a dermic ; the former is scarcely
to be regarded, however, as anything more than an appendage
to the dermic part, which is the true duct, it being little more
than a definite channel through the epidermis.

It seems to me, however, to be incorrect to describe the
epidermic portion of the duct as commencing in the deep
layer of the epidermis ; it extends beyond and far deeper
than this, for it lines the whole length of the true duct, and
this not merely with loosely aggregated cells, but these are
so united together as to form a distinct tubular membrane,
which by maceration may be exhibited as such (see Plate
XXIII. fg.2.)\ the epidermic cells become, in fact, con-
tinuous with those of the sudoriparous gland itself.

Mr. Rainey has noticed the fact that the secretion of the
sudoriparous glands in the palms of the hands and soles of
the feet, where the sebaceous glands are entirely wanting, is
of a greasy character ; from this circumstance he draws the
conclusion that these glands secrete both sweat and sebaceous
matter, the former in their more active state, the latter in
their less active condition.

It is only in the hands and feet, where the epidermis is
thick, that the epidermic portion of the sudoriparous duct
assumes importance.

INDEX.

Page
ADAMS, Mr. On the calculi of

the prostate - 424

ADDISON, Dr.

His belief in the existence of a
nucleus in the red blood disc 30

Views on the structure of the
red blood corpuscle - -32

Observations on the white cor-
puscles of the blood - 42

Further observations on the
same 45. 52

His opinion that milk, mucus,
and bile are the visible fluid
results of the first dissolution
of the cells - - 46

His opinion that the white cor-
puscles are the foundations of
the tissues and the special
secreting cells - 47

On the presence in increased
quantities of the white cor-
puscles in the hard and red
basis of boils and pimples,
and in the skin in scarlatina 50

His opinion that mucous and
pus globules are altered co-
lourless blood corpuscles - 129

His opinion that out of the
white corpuscles of the blood,
all other corpuscles met with
in the body are formed - 130

On the action of liq. potass, on
pus - - 144

On epithelial scales in the air
cells of the lungs - - 381

On tuburcles of the lungs - 386
AGGREGATED or FEVER'S glands - 398
ALBINOES, state of pigmentary

cells in - 259

Hair of 276

Page
ALBINUS. The first describer of

the nail - 254

ALPACO, blood of - - 27

AN SELL. On the increased quan-
tities of white corpuscles in
the blood in inflammatory
affections - 5O

ANDRAL and GAVARRET.

On the mammillated appear-
ance of the red blood discs - 85
Important researches on the pa-
thology of the blood - 90
ANDRAL, A. G. CAMUS, and LA-
CROIX. On the pacinian bo-
dies - - 368
ANELID^E, blood of - 14
ARACHNOID MEMBRANE - - 544
Ganglionary character of - ib.
AREA VASCULOSA - - 75
AXILLA. New tubular gland in

Plate LVII.
AXILLARY glands. Structure of - ib.

BALY. His opinion that the
white globules are red blood
corpuscles in process of form-
ation - - 53
BARRY, Dr.

His belief in the existence of a
nucleus in the human red
blood disc - - - 30

Views on the structure of the
red blood corpuscle - 32

Views on the white blood cor-
puscle - 47

His opinion that the tissues are
formed by direct apposition
of the blood corpuscles - ib.

His discovery of spermatozoa
on the ovary - - 200

552

INDEX.

Page

BAT. Hair of - - - 279

BEAR. Spermatozoa of - - 188

BECLARD. On the disappearance

of the fat vesicle - -231

BEQUEREL and RODIER. Re-
searches on the blood - 109
BERZELIUS. Analysis of healthy

urine - - - 214

BIDDER.

On the perephral distribution
of the gelatinous nerve fila-
ments - - 363
On the structure of the kidney 438
On the structure of the malpi-

ghian body - - 439

BILE. - 210

Epithelium in - - 211

Cell-like bodies in - - ib.

Corpuscles of liver in - - ib.

Meconium - ib.

BIRDS, fat of - 223

Malpighian bodies of - - 455

BISCHOFF.

His discovery of living sperma-
tozoa in the rabbit eight days
after intercourse - - 192

His discovery of spermatozoa
on the ovary itself -

- 200

On the structure of the kidney 438
BLOOD - - 13

Definition of - - - ib.

Red blood - - - 14

Colourless blood - - ib.

Composition of - ib.

Coagulation of without the body ib.
Death of - ib.

Quantity of in the body - ib.

Blood of annelidae - - ib.

Clot - - 15

Coagulation of blood within

the vessels after death - 21

Motling of - - 22

Fluid state of after death - 23

Globules of - - 24

Red - - 25

White - - - 39

Venous and arterial blood - 80
Causes of inflammation - 87

Exciting cause - - ib.

Proximate causes - - 88

Pathology of blood - - 89

Blood in the menstrual fluid - 1 1 1
Transfusion of blood - - 112

Importance of a microscopic

examination of the blood in

criminal cases - -110

Blood stains, how detected by

the microscope - - ib.

BONE - 294

Structure of - - - ib.

Cancellous structure - - ib.

Lamellee of - - ib.

Medullary cells of - ib.

Communications of - - 295

Contents of - - ib.

Canal icular structure of - ib.

Haversian canals of - - 296

Contents of ditto - - ib.

Arterial and venous haversian

canals - - - 297

Lamellse - ib.

Number and arrangement of

ditto - ib.

Structure of ditto - - 298

Bone cells - 299

Differences of opinion as to na-
ture of - ib.
Form of - 300
Canaliculi of - - - ib.
Size of bone cells in different

animals ... ib.
Development of ditto - - 309

Comparison of to stellate pig-
ment - 310
Marrow of bones - - 301
Periosteum of ditto - - ib.
Vessels of ditto - - ib.
Nerves of ditto - -302
Growth of ditto - - 303
Development of ditto - - 304
Intra-membranous form of ossi-
fication - - ib.
Intra-cartilaginous form of ditto 305
Formation of medullary cavity 310
Ditto of medullary cells -312
Ditto of haversian canals - ib.
Accidental ossification - 313
BOWERBANK, Mr. On the size of

the human blood disc - - 27

BOWMAN, Mr.

On the lining membrane of the

fallopian tubes - 396

His doubts as to the existence

of a lobular biliary plexus - 41 1
His opinion that the series of
secreting cells represent the
continuance of the biliary
ducts - - - 417

On the ciliated epithelium at
the neck of the malpighian
dilatations - 430

His opinion that the afferent
vessel of the malpighian tuft
pierces the dilated extremity
of the tube - - 432. 439

On the termination of the renal

INDEX.

553

Page

artery on the malpighian bo-
dies - - 433
On the uses of the malpighian

body - - - 434

BRANCHIOSTOMA LUBRICUM - 14. 58
BRESCHET.

On the presence of Pigment in
the membranous labyrinth of
the ear of mammalia - 258

On imbibition of cartilages - 289
On the communication of the

medullary cells of bone - 295
On a system of osseous canals

in flat bones - - 302

BREWSTER, Sir David, on the fibres

of the crystalline lens -521

BRONCHIAL GLANDS - - 404

BRONCHIAL tubes - - 379

Structure of - - - ib.

Larger tubes - ib.

Smaller ditto - ib.

Mucous mambrane of - - ib.

Epithelium of- - - ib.

Muscular fibre of - ib.

BRUNNER'S glands - 405, 406

Structure of - - - 406

Distribution of. (Vide Mu-
cous Glands.)
BRUNS.

On the membrane lining the

cavities of the true cartilages 282
On the nature of bone cells - 300
BUCCAL glands - 404

BUFFY COAT OF BLOOD, conditions

favourable to the formation of 20

CADAVERIC RIGIDITY - - 350

CAPYBERA, blood of - 28, 29

CAMELIDJE.

Blood of - - 27

Of dromedary - ib.

Ofalpaco ... ib.

Of vicugna - il.

Of llama - ib.

CARNIVOKA, blood of - 28

CARPENTER, Dr.

On the structure of the striated
muscular fibrilla - - 311

On the analogy between striped
and unstriped muscular fibres 354

On the analogy between certain

cartilage cells andcertain algae 29 1
CARTILAGE.

General structure of - - 281

Division of, into true and false - ib.

True cartilages - ib.

Enumeration of - ib.

Structure of - - - 282

Matrix of
Cavities of
Primary cells of
Secondary cells of
Nuclei of

Page

- 282

- ib.

- ib.

- ib.

- ib.

Distinction of cartilage into true
and false or fibro cartilages,

to some extent artificial - 285

Conversion of true into fibro

cartilage - - ib.

Union of true cartilage with li-
gament - - - ib.

Fibro-cartilages - - ib.

Structure of - - - ib.

Cells of 286

Fibres of - - ib.

Enumeration of ib.

Nutrition of cartilage - - 287

Pericondrium of - 288

Vessels of cartilage - - ib.

Pathology of - - - ib.

Ossification of ib.

Ulceration of - - - ib.

Atrophy of - - - 289

Growth and development of car-
tilages - ib.

Of the cells - - - ib.

By division of ditto - - ib.

By cytoblasts - ib.

By parent cells - 290

Comparison of cartilage cells to

certain alga? - - ib.

Growth and development of the

intercellular substance - 291

By a deposit of new layers - ib.

By thickening of the walls of

the cavities - - ib.

Enchondroma - 292

Uses of cartilage - - ib.
CARUNCULA LACHRYMALIS, struc-
ture of 402
CAT, bulb of hair of - - 27&

Blood vessels of stomach of - 395

CEREBELLUM, ganglion cells of

arbor vitas - 357

Ditto of corpus dentatum - ib.

CERUMINOUS glands - - 426

Structure of - - - 427

CHYLE - - - - 3

Analysis of - 5

Molecular base of - ib.

Granular corpuscles of - ib.

Chylous blood - - ib.

Oil globules of chyle - - 6

Minute spherules of - - ib.

Coagulum of - - - ib.

Serum of - - ib.

Nature of - ib.

554

INDEX.

Page

Contrasted with lymph - 6

Colour of in thoracic duct - 7
CILIA - - - -239

CIRCULATION, capillary - - 69

In embryo of the chick &c. - 74
(Extremities of young spiders,
fins of fishes, gills of tad-
pole and newt, tail of water
newt, web of frog's foot and
tongue of frog.)
CLOT.

Formation of - - - 1 5

Ditto in blood after freezing - ib.
Constitution of - 16

Length of time for formation of ib.
Characters of in health and dis-
ease - - - 17
Ditto of in diseases of a sthenic

character - - 17, 18

Ditto in diseases of an asthenic

character - ib.

Softening of fibrum - - 1 8

Buffy coat of clot - - ib.

Mode of formation of - - ib.

Adherence of red corpuscles in
roles in clot of inflammatory
blood - - - 19

Conditions favourable to the

formation of clot - -20

Clipping of - - - ib.

To what owing - - ib.

Condition of red globules in - ib.
COLOSTRUM - 160

Corpuscles of - - 161

Disappearance of ditto - 162

Colostrum corpuscles peculiar

to the human subject - ib.

Purgative qualities of colos-
trum - 163
Division of pregnant women
into three classes founded on
its characters - 168
COMPARETTI. On the presence of
pigment in the membranous
labyrinth of the ear of mam-
malia - - - 258
COPPIN, Mr. J. On the circula-
tion in the tongue of the frog 73
CORPORA WOLLFIANA - - 436
CORPUSCLES.
Of the blood.

lied corpuscles - - - 25

Colouring matter of - - 34

Uses of - - - 35

Causes of colour of 36

Iron in - ib.

Origin of - - - 57

Phases of the development of - 58

Page

Final condition of - 62

Blood globules of reptiles, fishes

and birds - - - 66

Ditto of camelidae - - 67

Ditto of the embryo of fowl - 76
Ditto of young frog - - 77

Blood corpuscles, dissolution of 78.
Blood corpuscles of adult fowl ib.'
Ditto of tritons and frogs - 79
Effects of reagents on the red

corpuscles - - 81

Modifications the results of dif-
ferent external agencies - 85
Ditto the effect of commencing

dessication - - ib. •

Ditto the result of decomposi-
tion occurring in blood aban-
doned to itself, without the
body - - 86

Ditto the effect of decomposi-
tion in the blood within the
body, after death - - 87

Effects of certain remedial
agents upon the constitution
and form of the red blood
corpuscle - - 114

Effects of iodine on ditto - 116

Peculiar concentric corpuscles

in blood - - 64. 66

White corpuscles of blood - 39

Number of - - ib.

Size of ib.

Form of - 40

Structure of - - ib.

Nucleus of - - 41

Properties of - - 42

Position of in capillaries - 43

Motion of in ditto - - ib.

Uses of connexion with secre-
tion - 45
Ditto in connexion with nutri-
tion - - 47
Aggregation of in capillaries - 48
Increased quantities of in dis-
ease - - - 49
Processes by which they may
be separated from the red
globules - - - 50
Origin of - 51
Opinions concerning - - ib.
Different names for - 52, 53
("Central Particles" of Hew-
son ; " Escaped Nuclei ; "
" Parent Cells " of Barry ;
" Tissue Cells " of Addison ;
" Fibrinous Globules " of
Mandl ; " Granule Cells "
of Wharton Jones j " Exuda-

INDEX.

555

Page

tion Corpuscles " of Gcrber ;
" Lymph Corpuscles " of
Miiller.;

Of Mucus - - -126

Structure of - - - ib.

Nuclei of, single and compound ib.
Form of 127

Size of - - - 128

Properties of - - - ib.

Nature of - - 129

Identity of with the pus cor-
puscle - - ib.
Mucous corpuscles, young epi-
thelial scales - 132
. Of Pus. Identity of pus with

mucous corpuscles - - 137

Nature, origin and formation of

pus corpuscles - 138

COWPER'S glands - - 405. 407

CRUSTACEA, fat of 223

CRUSTA PETROSA - - 314

CRUVEILHIER, on the calculi of the

prostate - - 424

DAW, Dr.

On the increased quantities of
white corpuscles in the blood
in inflammatory affections - 49

On the presence of spermatozoa
in the fluid of the urethra
after stool in a healthy man 202
DEATH. Signs of - • 21

Real and apparent. - 22

Coagulation of the blood, the

most certain sign of - - ib.

DELLA TORRE. On the annular

form of the red blood disc - 30
DONNE.

His disbelief in the existence of
a nucleus in the red blood
disc - - - 16.

On the increased quantities of
white corpuscles in the blood
in disease - - - 50

Opinions in reference to the
blood globules - 53

His opinion that the white glo-
bules, are red blood corpus-
cles in process of formation - ib.

His observations on the conver-
sion of milk globules into
white corpuscles - - ib.

On the transition of white glo-
bules to red corpuscles - 54, 55

Reasons in favour of the opinion
that the red globules are
formed out of the white - 75

Opinion of, as to the cause of

Page

the mammillated appearance
of the red blood discs - 85

Vaginal tricho-monas of - 134

Vaginal vibrios of - - 135

Opinions as to the nature of pus

globules - 141

Venereal vibrios of - - 150

On cheese globules - - 154

The discoverer of colostrum

corpuscles - - 161

His statement that the colos-
strum corpuscles are soluble
in ether - ib.

On the recurrence of colostrum 164
Condition of milk after confine-
ment, inconstant relation with
its state during gestation - 168
His division of pregnant women
into three classes, founded on
the characters of the colo-
strum during the last months
of gestation "* ib.

Lactoscope of - - - 173

On the formation of butter - 1 77
His detection of the spermatozoa

in the vagina on the second day 1 92
DROMEDARY. Blood of - - 27

DUJARDIN.

On the human spermatozoon 187, 188
His statement that spermatozoa
lived thirteen hours in the
testicle after death - - 192

EAR, structure of. See Hearing,
organ of - - - 522

EBLE.

On the hair at its full terra of

development - 272

On nerves in the bulb of the
hair of the cat - 279

ELEPHANT. Blood of - 28, 29

Malpighian bodies of - - 436

ENCHONDROMA - - 292

EPIDERMIS.

Form, size, and structure of

cells of - 247

Correspondence of to epithelium ib.
Disposition of - 248

Ditto of lines on the surface of 249
Effects of water on - ib.

Epidermis of white and co-
loured races - - 25G
Destruction and renewal of - ib.
Uses of - - 251
Pathology of - - 249

EPITHELIUM.

Constitution of 233

Distribution of 234

X X

556

INDEX.

Different forms of

Tesselafed variety

Form of cells of

Size of

Structure of -

Distribution of

Conoidal variety

Form and size of cells of

Structure of -

Naked conoidal variety

Distribution of

Ciliated variety

Distribution of

Development and mu
tion of epithelium -

Nutrition of ditto

Destruction and ren<
ditto

Uses of

EUSTACHIAN glands
EVANS, Dr. Julian. (

structure of the spleen
EYE. See Vision

FAT.

Vesicles of -

Contents of ditto

Form of ditto -

Size of ditto -

Colour of ditto

Consistence of ditto

Structure of ditto

Distribution of fat

Quantity of -

Disappearance of

Uses of

Distinction of fat vesicles from
oil globules -

Development of the fat vesicle
FIBRIN. Softening of

Fibrillation of-
FIBROUS TISSUE

White Fibrous Tissue -

Enumeration of parts
tuted of -

Morphous form of

Amorphous form of

Condensed form of

Reticular form of

Areolar form of

Structure of -

Action of acetic acid on

Yellow fibrous tissue

Enumeration of parts consti
tuted of

Structure of -

Varieties of

Peculiar arrangement of

Page
- 235
- 16.
- ib.
- ib.

Page
Mixed fibrous tissue - - 336
Nuclear form of fibrous tissue - 331
Development of white fibrous
tissue - 335

- ib.
- 236
- 237

Ditto of yellow fibrous tissue - ib.
FISHES. Bone cells wanting in
bone of 300

- ib.

FLUIDS.

- ib.
- 238
- ib.
- 239

Organised - - 1
Lymph - - 3
Chyle- - - - ib.
Blood - - - 13

- 241

Mucus - - - 122

tiplica-

Pus - - 137

- 242

Semen . - - 181

- 243
val of

Unorganised - 207
Saliva ... 208

- ib.

Bile - 210

- 244

Sweat- - - - 211

- 404

Urine- - - - 213

n the

Pancreatic fluid - -239

- 483
- 505

Lacrymal ditto - ib.
Gastric ditto - ib.

FOLLICLES.

Of stomach - 393

- 222

Of small intestines - - ib.

- ib.

Of Lieberkiihn - - ib.

- ib.
- 223

Of large intestines - - ib.
Form of ib.

- ib.
- 224

Epithelium of - 393, 394
Blood-vessels of - ib.

- ib.

Follicles of uterus - -396

- 229
- 230
- 231
- ib.

Of fallopian tubes - - ib.
Of vagina - - 403, 404
Of oesophagus - - 403
Of neck of uterus - 403, 404

>s from

Of vesicula seminalis - - 403

- 232
vesicle 538
- 18

Of Schneiderian membrane 403, 404
FROG, tongue of. Mode of exhi-
bition of 70

- 335

•

- 327

GALL BLADDER. Structure of - 415

- 328
consti-

GALLING. Spermatozoa of - 183
GASTRIC JUICE - - - 219

- ib.

GERBER.

- ib.

On the relation between the

- ib.
- ib.

- ib.

size of the blood globules and
the capillaries * - 29
His belief in the existence of a

- ib.

nucleus in the red blood disc 30

- i':
- 329

- ib.
consti-

On the structure of the sperm-
atic animalculi of the guinea-
pig - - 188
On the stellate bodies observed

- 330
- 329
- 330

in decomposing fat vesicles - 228
His description of the epithe-
lium of the ventricles as a

- 332

tesselated ciliated epithelium 242

INDEX.

557

Page

On nerves in the bulb of the

hair of the guinea-pig - 279
On the nature of bone cells - 310

GERLACH.

On the structure of the kidney 438

On the structure of the mal-

pighian capsule - - 439

GINGIVAL glands - - 405

GLANDS.

Definition of - - - 389

Classification of - 390, 391

a. Unil ocular glands - - 393

Follicles of stomach - - ib.

Ditto of large intestines - ib.

Ditto of Lieberkiihn - - ib.

Stomach tubes - - 395
Fallopian and uterine tubes or

follicles - - - 396

Solitary glands - - 397
Aggregated or Peyer's glands - 398

6. Multilocular ditto - - ib.

Sebaceous ditto - - ib.

Meibomian ditto - - 400

Glands of the hair follicles - 401

Caruncula lachrymalis - 402

Glands of nipple - - ib.

Ditto of prepuce - - 403

Mucous glands - - ib.

Labial ditto - - - 404

Buccal ditto - ib.

Tonsillitic ditto - ib.

Lingual ditto - ib.

Tracheal ditto . - - ib.

Bronchial ditto - - ib.

Palatine ditto - ib.

Pharyngial ditto - - ib.

Glands of uvula - - ib.

Ditto of Eustachian tubes - ib.

Brunner's glands - ib. 406

Cowper's ditto - 405. 407

Gingival ditto- - ib.

Uterine ditto - - - ib.

Vaginal ditto - 405

Lenticular ditto - - ib.

c. Lobular ditto - 407
Salivary ditto - - ib.
Mammary glands - - 408
Liver - - - 409
Prostate gland - - 422

d. Tubular glands - - 424
Sudoriferous ditto - - ib.
Axillary'ditto - 426
Ceruminous ditto - - 427
New tubular gland in axilla:

kidneys • ib.

Teslis- - - - 475

g. Vascular glands « - - 477

Thymus gland - - ib.

Page

Thyroid gland - - 479

Supra-renal capsule - - 481

Spleen - 483

/. Absorbent glands - - 486

Lacteal or mesenteric glands - 487

Lymphatic glands - - ib.

Villi of intestines - - ib.

GLOBULES of milk - - 155

GOAT, blood of - - 28, 29

GOODSIR.

On the general development of
the teeth - - 321

On the classification of glands - 390

On the epithelium of the villi - 488

On the cells developed during

absorption in ditto - - 489

GRALLJE. Spermatozoa of - 183

GRUBY and DE LA FONT, M.M.

On blood discs in chyle - 7

GUETERBOCK. His opinion that
the colostrum corpuscles are
true cells - - 161

GUINEA-PIG, spermatozoa of - 183
GULLIVER, Mr.

Observations on the molecular
base of the chyle in the blood 5

On the lymphatics of the spleen 7

On the characters of the blood
discs in the chyle - 8

His opinion in favour of Hew-
son's views of the thymus - 9

On the blood of the Vicugna
and Llama - - - 27

On blood corpuscles in states of
disease - - - 28

On the relation in the size of
the blood corpuscles amongst,
the mammalia, and that of the
animal from which they pro-
ceed - ib.

On the dimensions of the red
blood discs of the elephant,
capybara, and napu musk-
deer - - - 29

His disbelief in the existence of
a nucleus in the red blood disc 30

His measurement of the human
colourless blood corpuscle - 39

His observations on the presence
of white corpuscles in the
blood in unusual quantities in
inflammatory affections - 49

His opinion that the white glo-
bules are red blood corpuscles
in process of formation - 53

His opinion that blood discs are
the escaped nuclei of the white
corpuscles - 60

xx 2

558

INDEX.

.Page
On the blood of birds after a

full meal - - - 61

On concentric corpuscles in the
blood, which he has styled
" Organic Germs," or " Nu-
cleated Cells " - - 65
GURLT. His statement that the fat
vesicles in lean animals con-
tain serosity, and not grease 251

HAIR .... 263

Form of ib.

Size of - 264

Structure of - - - ib.

Ditto of root of 265
Ditto of bulb of - - 265. 549

Ditto of sheath of - ib.

Ditto of shaft of - 267

Ditto of cortex of - ib.

Ditto of fibrous layer of - 268
Ditto of medullary canal of - 269

Ditto of follicle of - - 270

Growth of hair - - 271

Regeneration of 272

Nutrition of - - - 273

Distribution of - 274
Number of hairs in different

situations - ib.

Erection of - - 275

Colour of - - 276

Grey hair - - - 277

Properties of hair - - ib.
Hairs of different animals - 278
(Of the musk deer, sable,

mouse, bat, martin) - ib.

Uses of hair - 279

HAIR FOLLICLES. Glands of - 401

Distribution of ib.

Structure of - - - ib.

Binary arrangement of - ib.

Steatozoon folliculorum - 402

HAIULEN. Inorganic components

of milk of cow, according to 296

HAVERS. Glands of - - 230

HAVERSIAN CANALS - - 296

HEARING. Organ of - 522

External ear - ib.

Auricle, structure of - - ib.

Cartilages of - - - ib.

Muscles of - - - 523

Auditory canal - - ib.

Cartilaginous part of - - ib.

Osseous ditto - - ib.

Sebaceous glands of - - ib.

Ceruminous ditto - - ib.

Muscular fibres in - ib.

Middle ear - ib.

Tympanum - ib.

Page

Structure of - - - tb.

Tympanic cavity - _ 524

Structure of membrane of - ib.

Openings into - _ 524

Ossicles and muscles of - ib.

Transparent cells in - ib.

Pigment cells in - ib.

Internal ear - 525

Osseous labyrinth - - ib.

Membranous ditto - - ib.

Perilymph - . ib.

Endolymph - ib.

Structure of the spiral lamina
of the cochlea - - ib.

Denticulate lamina - - 526

Membranous zone - - 527

Structure of the cochlearis mus-
cle - - - - ib.

Cochlear ligament - - 528

Muscular zone - - ib.

Epithelium of scalse - - ib.

Structure of the cochlear nerves 529

Of the membranous labyrinth - ib.

Utriculus - - 530

Sacculus - - ib.

Membranous semicircular canals ib.

Otolith - - - 531

Otoconia - ib.

Of the vestibular nerves - 532

Of the auditory nerves - 533

HEDGEHOG. Structure of spines of 279
HENLE, M.

Theory of the changes of the
colour of the blood - - 83

Opinions as to the nature of the
white corpuscles of blood,
lymph, chyle, mucus, and pus 130

Opinions on the structure of the
milk globules - -156

On the application of acetic acid
to the milk globules - 157, 158

His opinion that the colostrum
corpuscles are aggregations of
granules in a mucoid sub-
stance - - 161

On the structure of spermatozoa 187

On the membrane of the fat
vesicle - 224

On the nucleus of the fat vesicle 225

On the stellate bodies observed
on decomposing fat vesicles - 228

On the presence of fat in the
blood after repeated bleedings 231

On the absence of epithelium
in the bursce - 234

His description of the epithe-
lium of th/e ventricles as a
cuneiform ciliated epithelium 242

INDEX.

559

Page

On the position of the pigment
granules in the cells - 259

On the fibres of the fibrous layer
of the hair - - 268

On the medullary canal of hair 269

On the arrangement of the cells
of articular cartilage - 283

On certain large cells, present-
ing in their interior a cavity
in the cartilage of the epi-
glottis - 287

On the membrane of the cavi-
ties of true cartilage - 288

On the increase of the inter-
cellular substance of carti-
lages by the thickening of the
membrane of the cavities - 291

On the structure of the lamellae
of bone ... 298

On the nature of bone cells - 310

On the structure of the inter-
tubular substance of dentine 316

On a peculiar arrangement of
the fibres of elastic tissue -332

On the disposition of gelatinous
nerve fibres - - - 362

On the proportions of gelatinous
nerve filaments in different
nerves - - 363

On the arrangement of the ge-
latinous nerve filaments in
ganglia ... 355

On the development of nerve
cells on the surface of the con-
volutions of the brain - 373

On the epithelium of the cho-

roid plexuses - - 537

HERBIVORA. Blood of - - 28

HEWSON.

On the lymphatics of the spleen 7

His opinion that the thymus is
an appendage to the lym-
phatic system, chyle globules,
or the corpuscles of the thy-
mus - 9

His belief in the existence of a

nucleus in the red blood disc 30
HODGKIN. His disbelief in the
existence of a nucleus in the
red blood disc - - ib.

H^EMATINE - - 33

HOOKE. On the hair - - 270

HORNER, Professor. On the ax-
illary glands - - 426

HUNTER. On the persistence of

fat vesicles - - 231

HUSCHKE. On the structure of

the kidney ... 438

Page

INFLAMMATION. Causes of 87,88
Exciting cause - - ib.

Proximate cause - - ib.

JACOBI. Experiments in fertilising

the ova of a carp - - 201

JOHNSON, Dr. G.

On fatty degeneration of the
kidney - - 442. 458

On the inflammatory diseases

of ditto - - - 452

JONES, Mr. Wharton.

On the presence of a nucleus in
the blood disc of the lamprey 27

On the mulberry or granulated
appearanceof the red blood disc 37

On the structure of the red
blood corpuscle - - ib.

Opinions concerning the white
blood corpuscles - - 52

Observation on the blood cor-
puscle, considered in its dif-
ferent phases of development
in the animal series - - 58

On the nuclei of mucous cor-
puscles - - 127

On the brown pigment of the
membranous labyrinth of the
ear of man - - 258

On the tubular character of the
gelatinous nerve filaments - 363

On the structure of the ganglion

csecum in the dog - - ib.

JONES, Dr. Hanfield.

Reasons for his non-belief in
the existence of a lobular bi-
liary plexus- -411

His investigations as to the ter-
minations of the biliary ducts 412

On the arrangement of the he-
patic cells in connection with
secretion - - - 413

On the union and consolidation
of the hepatic cells - - ib.

Description of the active and
passive conditions of the lo-
bules of the liver - - 415

On the development of the liver 422

On the calculi of the prostate - 424

On peculiar corpuscles in the
spleen - 485

On the epithelium of the villi 488

On the granular substratum in
ditto - 489

On oil drops in ditto - - ib.

KIDNEV.

Secreting apparatus of -

x x 3

- 428

560

INDEX.

Page

Tubes of - . -428

Tubes of, in cortical part - ib.

Tubes of, in medullary part - ib.

Basement membrane of - 429

Framework for the lodgment of
tubes - - ib.

Malpighian dilatations - ib.

Vessels of - - 430

Capsules of - ib,

Epithelium of the tubes - ib.

Ditto of Malpighian dilata-
tions - ib.

Ditto of neck of Malpighian di-
lations j - - ib.

Vascular apparatus of kidney - 431

Renal artery - ib.

Renal vein - ib.

Intertubular plexus - - ib.

Portal vein - 432

Portal system - - - ib.

Afferent vessel of Malpighian
tuft- - - ib.

Efferent vessel of Malpighian
plexus - ib.

Malpighian body, structure of,
when complete - - 434

Malpighian bodies of birds and
reptiles ... 435

Size of 436

In elephant and birds - - ib.

Development of the kidney - ib.

True capsule of the Malpighian
tuft - - 440, 44 1

Pathology of the kidney -442

KlERNAN.

His description of the biliary
ducts, and of the lobular bi-
liary plexus - - 410

On the acini of the liver - ib.

KIESER. On the pigmentary

membrane of the eye - 257

KCELLIKER.

On the absence of internal or-
gans in spermatozoa - 189
On the development of sperma-
tozoa - 196
On the structure of the kidney 438
LABIAL glands - 404
LACHRYMAL glands - - 405
LACHRYMAL fluid - - 219
LACTEAL or MESENTERIC glands - 487
LACTOSCOPE - - - 173
LALLEMAND. On the develop-
ment of spermatozoa - 195
LAMBOTTE. His disbelief in the
existence of a nucleus in the
red blood disc - 30
LAMINA FUSCA pigment, cells of - 260

Page

LAMPENHOFF. On living semen
in the vesiculae seminales of
dead men - - - 192

LAMPREY. Blood of - - 27

LANE, Mr.

Analysis of chyle - - 5

On blood discs in the chyle - 8
His belief in the existence of a

nucleus in the red blood disc 30
Views on the structure of the

red blood corpuscle - - 32

LLAMA, blood of - - - 27

LETHEBY, Dr. H.

On cell-like bodies in the bile - 210
On the calculi of the prostate 424
LEEUWENHOEK.

The first to describe the blood

globules in different animals 25
The discoverer of milk globules 155
His discovery of living sperma-
tozoa in the uterus and fal-
lopian tubes of a bitch, seven
days after connection 192, 199
On the discovery of sperma-
tozoa - - - 182
On the spermatozoa of the ram

and rabbit - - 188

The discoverer of epithelium
cells in the mucus of the va-
gina - 233
The first to observe that the
epidermis was composed of
scales - 247
On the hair - - - 270
LENTICULAR glands - - 405
LIEBIG.

On the condition of iron in the

blood - - - 36

LIQ. POTASS., action of, on pus 46, 144

LISTON, Mr. His disbelief in the

existence of a nucleus in the

red blood disc - - 30

LINGUAL glands - 404

LIVER - 409

Secreting apparatus of - - 41O

Lobules of - ib.

Form of ib.

Size of - ib.

Union of - ib.

Interlobular fissures - - ib.

Interlobular spaces - - ib.

Follicles, or acini - - ib.

Biliary ducts - ib.

Lobular biliary plexus - ib.

Doubts concerning - - 41 1

Mode of termination of - 412

Structure of - - ib.

Secreting cells - 413

INDEX.

561

Page

Structure of - - - 413

Linear and radiated disposition of ib.

Union of - - ib.

First secretion of bile in central

cells - - -414

Active and passive conditions of

the lobules of the liver - ib.

Dissolution of membrane of - 415

Gallbladder - - - ib.

Structure of - - ib.

Vascular apparatus of liver - 417
Hepatic veins - ib.

Central lobular veins - - ib.

Sublobular veins - - ib.

Portal veins - ib.

Jnterlobular veins - - ib.

Lobular capillary plexus - 418

Hepatic artery - - 419

Pathology of liver - - ib.

Development of - - 422

PROSTATE gland - - ib.

Structure of - - - ib.

Epithelium of 423

Calculi of - - ib.

Increase of in old age - - ib.
Locus NIGER. Ganglion cells of 357
LUNGS - 378

Aeriferous apparatus of - 379

Bronchial tubes - - ib.

Air cells - ib.

Form of ib.

Size of ib.

Structure - ib.

Communications of - 380

Models of - - ib.

Epithelium of ib.

Vascular apparatus of - - 381
Arteries ... ib.
Veins - ib.

Capillaries - - 382

Natural inflation of lungs - ib.

Artificial ditto - ib.
LYMPHATIC glands. Structure of 487
LYMPH - - - 3

Analysis of - - 4

Coagulum of - - - ib.

Granular corpuscles of 5

Serum of - - 6

LYMPHATIC system - 3

Structure of lymphatics - ib.

Ditto of lacteals - 4

Ditto^of lymphatic glands -487

Ditto of mesenteric glands - if>

Thoracic duct - 4

Blood in lymphatics of spleen - 7

MADDER. In bones of animals

fed with - ' - 303

Page
MAJENDIE.

His disbelief in the existence of
a nucleus in the red blood
disc - - 30

Experiments of, on the blood - 103
MALPHIGI. The discoverer of

the red globule - - 24

MAMMARY GLANDS - - 408

Structure of - - - ib.

Efferent ducts of - - ib.

Milk globules in follicles of - 409
Follicles of - - ib.

Existence of mammary gland

in the human male - - ib.

Epithelium of - - - ib.

Degeneration of mammary

gland in age - - ib.

Lacteals of - - ib.

MAN. Spermatozoa of - - 183

MANDL.

On the blood of the dromedary

and alpaco - • 27

His belief in the existence of a

nucleus in the red blood disc 30
Plis opinion that the formation
of the nucleus of the blood
corpuscles of reptiles takes
place subsequently to the re-
moval of the blood from the
system - - - 67

Opinion as to the nature of pus

and mucous globules -140

Opinion as to the structure of

milk globules - - 156

On the structure of the fat ve-
sicle - - - 225
On stellate bodies observed in

decomposing fat vesicles - 228
MARTIN. Structure of hair of - 279
MAYER, E. H. On the nature of

bone cells - - - 310

MEDULLA OBLONGATA. Ganglion

cells of - - - 357

MENOBRANCHUS. Bone cells of - 299

MEIBOMIAN glands - - 400

Number of - - - ib.

Form of ib.

Structure of - - ib.

MICKAUER. On the structure of

cartilage - - 287

MILK - - - 153

Inorganic components of - ib.

Organic constituents of - ib.

Analysis of - 170. 172

Serum of - 154

Cheese globules of * - - ib.

Fatty ditto of - - 1 55

Form, size and structure of - ib.

x x 4

562

INDEX.

Page
Opinions of observers as to the

structure of - 156

Action of boiling water, boiling
alcohol, the alkalies, acetic
acid, and aether on - - 159

Colostrum of - - - 160

Pathology of milk - - 163

Milk of unmarried women - 167
Ditto of women previous to

confinement - - ib.

Ditto of women who have been
delivered, but who have not
nursed their offspring - 169

Milk in the breasts of children ib.
Different kinds of milk - ib.

Relative proportions of the ele-
ments of milk in woman, the
cow, the goat, and the ass - 1 70
Good milk - - 171

Poor milk - - - 174

Rich milk - - - 175

Adulteration of milk - - 176

Formation of butter - - 177

Milk abandoned to itself - 1 78

Penicillum glaucum in - 179

Medicines in milk - - 180

MITSCHERLICH. Observations on

the saliva - 208

MONDINI. On the pigment of the

eye - 257

MOUSE. Spermatozoa of - 183

Structure of hair of - - 279

Mucus - 122

General characters of - - ib.

Ditto of true mucous mem-
branes ... 124
Ditto of false ditto • - 125
Ditto of mixed ditto - - ib.
Corpuscles of - - - 126
Mucus of different organs - 132
Vaginal and uterine ditto - 133
Effect of acid mucus on the

teeth - - ib.

Tricho-monas in vaginal mucus 134
Vibrios in ditto - 135

Distinctive characters of mucus

and pus - 141

Mucous MEMBRANES.

True or compound • 123.403

False or simple - - ib. ib.

Mixed - - - ib. ib.

Compound.

Alimentary canal from cardia

downwards - 403

Gall bladder - - - ib.

(Esophagus - - ib.

Vagina - - ib.

Neck of uterus - - ib.

Page

Vesicular seminales - - 4O3
Simple.

Eustachian tubes - - ib.

Trachea - ib.

Bronchial tubes - - ib.

Bladder - £6.

Unimpregnated uterus - ib.

Mixed.

Mouth

Nose -
Mucous GLANDS.

Structure of - - 405

Follicles of - - ib.

Epithelium of - 406

Membrane of - - - ib.

MULLER.

On blood discs in the chyle - 7
On the quantity of blood in

the system - - 14

On the coagulation of blood

after freezing - 15

On the blood of the frog - 1 6

His belief in the existence of a

nucleus in the red blood disc 30
His verification of the white

globules in the blood of a

frog - - 39

On spermatozoa - - 187

On the terminations of nerves

in the membrana nictitans - 368
On the kidney - 438

MUSCLE - 336

Voluntary - - ib.

Involuntary - ib.

Of animal life - - ib.

Of organic life - - ib.

Striped - 337

Unstriped « - ib.

General structure of muscle - ib.
Of unstriped muscular fibrilla - ib.
Nuclei of - - 338

Muscular structure of the

heart - - ib.

Of striped muscular fibre - 339
Size and form of - - 339, 340

Size of, in foetus - - 339

Ditto in adult - - ib.

Cause of striation of - 340, 34 1
Differences of opinion as to - ib.
Lacerti, or bundles of fibres - 340
Structure of fibrillas of fibres ib. 548
Nuclei of - - 342

Situation of, in the fibre - ib.

Sarcolemma - - 337. ib.

Cleavage of fibre -344

Blood-vessels of muscles - 338

Nerves of ditto - 345

Union of muscle with tendon - 346

INDEX.

563

Page

Muscular contraction - - 346

Active and passive contraction

of muscle - 347

Zigzag disposition of the fibres

in - - - - ib.

Approximation of the striae in 349
Increase in the diameter of the

fibre in 350

Rigor Mortis - ib.

Muscular sound - 351

Developments of muscle, three

stages of - - ib.

Differences of opinion as to

striation - - 341

MUSCULAR RIGIDITY. A sign of

death - -22

Music DEER. Structure of hair of 279

NAILS - - 253

Structure of - - - ib.

Development of 255

Pathology of - - 256

Modifications of in the animal
kingdom - ib.

Regeneration of ib.

Mr. Rainey on the structure

and formation of - - 541

NAPU MUSK DEER. Blood of 28, 29
NASMYTH Mr.

On the constitution of the Jin-
tertubular substance of den-
tine - - 316

On secondary dentine - - ib.

His opinion that the cementum
passes over the entire surface
of the enamel of the tooth 3 1 7. 325

On the development of dentine 321
NASSE, Professor.

On the adherence of the red
corpuscles in rolls - 19

On a mottled appearance cha-
racteristic of inflammatory
blood - - - 20

His opinion that the white glo-
bules are red blood corpuscles
in process of formation - 53

On the milk globules - - 159

On the speedy disappearance of
colostrum corpuscles in wo-
men who have borne many
children - - 162

NERVES,- ... 356

Cerebro-spinal system - - ib.

Sympathetic ditto - - ib.

Structure of nerves - - ib.

Of cerebro-spinal system - ib

Secreting, or cellular structure of ib.

Disposition of - - ib.

Page

Granular base of - 357

Granular cells of - ib.

Caudate ganglion cells - ib.

Distribution of ib.

Globular ganglion cells - 358

Distribution of ib.

Of the tubular structure - 359

Of the cerebrum - - ib.

Of nerves of special sense - ib.

Of cerebellum - - ib.

Of spinal cord - - ib.
Of posterior root of spinal

nerves - ib.

Of sympathetic system - ib.

Of motor nerves - - ib.
Varicose dilatation of the tubes ib.
White substance of Schwann

in - - - - 360

Axis cylinder - - - 361

Neurilemma - 360
Globules of white substance of

brain - - 361
Ditto of spinal marrow, and

nerves of special sense - ib.

Of sympathetic system - - 361

Structure of nerves of - - ib.

Gelatinous nerve fibres of - 362

"Where best seen - - ib.
Proportion of, in different

nerves - - ib.

Structure of ganglia - - 365
Tubular and gelatinous nerve

fibres in - - ib.

Arrangement of ib.
Ganglion globules and nerve

fibres in - - - ib.
Origin and termination of nerves 366
Origin in loops - - ib*
In ganglion cells - - 367
Termination in loops - - ib.
In definite extremities - 368
Blood-vessels of nerves - 366
Pacinian bodies - - 368
Development of nerve fibres - 371
Ditto of ganglionary cells - 372
Regeneration of nervous matter 373
Researches of M. Robin - 374
NESBETT. The first to distinguish
between the two forms of os-
sification - 304
NEURILEMMA ... 360
NIPPLE, glands of 402
NOSE. Structure of mucous mem-
brane of. See Smell.
NUTRITION, corpuscular theory of 37, 49

(ESOPHAGUS. Muscular fibres of,

striped and unstriped - 334

564

INDEX.

Page

OMNIVORA. Blood of - - 28

ORGANS of the senses - - 491

Touch - - - ib.

Taste - -494

Smell - 500

Vision - ib.

Hearing - 522

OWEN, Mr.

His disbelief in the existence of
a nucleus in the red blood
disc - - -SO

On the development of dentine 321

PACINI. On the Pacinian bodies 368

PACINIAN bodies - - ib.

Situation of - - - ib.

Structure of - - - ib.

Inner system of capsules of - 369

Termination of nerve in - ib.

Intercapsular ligament of - 370
Varieties in form and structure

of - - - - ib.

PACCHIONIAN glands - - 538

Situations of - - - ib.

Forms of - ib.

PALATINE glands - - 404

PALMIPEDES. Spermatozoa of - 183

PANCREATIC fluid - 219

PAPPENHEIM. On the structure

of the kidney - 438

PASSERES. Spermatozoa of - 183
PATHOLOGY.

Of the blood - - - 89
Of the red corpuscle - - 90
Increase of in plethora - 91
Decrease of in anaemia - 92
Increase of under the influence
of recovery and certain medi-
cinal agents - - 94
Effect of disease on the white

corpuscles - - - 95
Deficiency of fibrin in fevers,
typhus, small pox, scarlatina,

and measles - ib.
Increase of fibrin in inflamma-
tory affections, as pneumonia,
pleuritis, peritonitis, acute

rheumatism - - 98
Condition of the blood in h<z-

morrhages - - - 101
Decrease in the normal portion

of albumen - - - 104
Bequerel and Rodier's patho-
logical researches on the blood 109
Blood in ecchymoses - - 1 1 3
Of milk - - - 163
Persistence of, in the condition
of colostrum - - 163

Page

Recurrence of colostrum - 164

Influence of retention of milk - 164

Pus and blood in milk

The milk of syphilitic women - 166

The milk of women in case of

the premature return of the

natural epochs - 167

Of the semen - - - 201

Of the urine - - - 215

Albuminous urine - - ib.

Fibrinous ditto - - 21 6

Fatty ditto - - ib.

Chylous ditto - - - 217

Milky ditto - ib.

Excess of mucus in ditto - 218

Blood in ditto - ib.

Pus in ditto - - - 219

Of epidermis - - 249

Of nails - - - 256

Of pigment cells - - 258

Of cartilage - 288

Of the lungs - - - 383

Emphysema - 384

Asthma - - ib.

Pulmonary apoplexy - - ib.

Pneumonia - 385

Tubercles - - - 386

Of liver - - - 4 1 9

Secreting apparatus - - 419

Biliary engorgement of cells - ib.

Fatty engorgement of ditto - ib.

Vascular apparatus - - 420

Anaemic condition of lobules - ib

First stage of hepatic venous

congestion - - 421

Second stage of ditto - - ib.

Nutmeg or dramdrinker's liver ib.

Portal venous congestion - ib.

Hydatids of liver - - ib.

Cysts in liver - ib.

Of the bile - ib.

Of kidney ... 442

Fatty condition of - 442. 458

Pathology of" Bright's disease,"

according to Toynbee - 443

Sub-acute inflammation of the

kidney - 446

Cystic disease of ditto 448. 456

Inflammatory diseases of the

kidney - - 452

Acute desquamative nephritis - 453
Chronic ditto - 454

First form of fatty degeneration 458
Second form of ditto - - 459

Exudation - 460

Exudation within the tubes - ib.
A. Crystalline or saline de-
posits - - 461

INDEX.

565

Page

B. Oleo-alburninous exuda-
tion - - 461
c. Exudations in the form of

pus - 462

Exudation within the Malpi-

ghian bodies - - ib.

Exudation in the intertubular

tissue - ib.

Partial distribution of the oleo-

albuminous exudation - ib.

Lesions affecting chiefly the

vascular system - - 463

Congestion followed by per-
manent obliteration of the
capillaries of the cortical sub-
stance - 464
Waxy degeneration - - ib.
Lesions of the tubes and epi-
thelium ... 466
Imperfect development of the

cells and nuclei - - ib.

Disquamation of the epithelium 467
Obliteration of the tubes - 468

Microscopic cyst formation - 469
Dilatation and thickening of

the tubes - - - 471

Conclusion - - 472

Of thyroid gland. Condition of, in

goitre - 481

PA YEN. His analysis of the milk

of woman - - - 170

PEARSON. On the colouring mat-
ter of the lungs and bronchial
glands - - 259

PELIGOT, M. His observations
on milk retained for a long
time in the breast - - 164

PEYER'S glands - - 398

PHARYNGEAL glands - - 404

PIA MATER. Structure of - 537

Choroid plexuses of - - ib.

Velum interpositum of - ib.

Villi of - - ib.

Blood-vessels of ib.

Epithelium of - - ib.

PIG. Fat vesicles of - 223

Bulb of hair of - - 279

PIGMENT CELLS - - 257

Structure of - - - ib.

Situation of - - - 258

Pathology of - - - ib.

Freckles - ib.

Cells of the choroid - - 259

Of the iris and ciliary processes ib.
Of the lamina fusca - - 260

Pigment cells in the skin - ib.

Ditto of outer surface of cho-
roid - - - 261

Page

Pigment granules - - 261

PINEAL GLAND. 535

Caudate cells of - ib.

Compound and calcareous cells

of - - ib.

Earthy matter of - 536

Blood-vessels of 537

Nerve tubules of - - ib.

PITUITARY GLAND.

Lobes of 534

Structure of - - - ib.

Infundibulum of - - ib.

Comparison of, to a ganglion - 535

PORCUPINE. Bulb of spines of - 279

PREPUCE, glands of - - 403

PREVOST and DUMAS.

Their observations of living
spermatozoa seven days after
connection - - - 199

Experiments on the semen - 200
PROTEUS. Blood globules of - 67
Shape of bone cells of - - 299

PURKINJE. On the vibratile epi-
thelium of the ventricles - 241
PURKINJE and VALENTEN. On

ciliary motion - 239, 240

Pus - - 137

General characters of - - ib.

Distinctive characters of pus

and mucus - - 141

Action of liq. potass, and sol.

ammon. on pus - 46. 144
Distinctions between certain

forms of pus and mucus - 146
Detection of pus in blood - 147
False pus - - 149

Metastatic abscesses - - ib.

QUEKETT, Mr.

His disbelief in the existence of

a nucleus in the red blood disc 30
His opinion on the mammillated

appearance of the red blood

disc - - - 86

On bone cells ... SOO
On the calculi of the prostate 424
On looped blood vessels in the

olfactory region of the foetus 503

QUEVENNE, M.

On the cheese globules - 154

On the milk ditto - - 159

RAINEY, Mr.

On the structure and formation
of the nails - - - 541

On the ganglionic character of
the arachnoid membrane of
the brain and spinal marrow 544

566

INDEX.

Page

On healthy air cells - - 381

On the structure of the sudo-
riferous glands - - 549
On the synovial fringes - ib.

RAM. Spermatozoa of - - 188

RAPACES. Spermatozoa of - 183

RAPP.

On nerves in the bulb of the
hair of the seal, porcupine, &c. 279

RAT, spermatozoa of - 183

REES, Dr. G. O.

Analysis of lymph - 5

His belief in the existence of a

nucleus in the red blood disc 30
On the structure of the red

blood corpuscle - - 32

On the urine of persons taking
cubebs or copaiba - - 216

REICHART. On the kidney - 438

REPTILIA.

Blood globules of - 56

Form of ib.

Size of - 67

Structure of - - - ib.

Action of water on 68

Ditto of acetic acid on - ib.

White globules of - ib.

Plastic properties of red ditto - 69
Fat of reptiles - 223

Malpighian bodies of - - 426

RESPIRATION. Corpuscular theory

of - - 37

RHINOCEROS. Blood of - 28, 29

RIGOR MORTIS - - - 350

ROBIN, M. C.

Researches on the nervous sys-
tem - 374
On the axillary glands - 426

RODENTIA. Hair of - 279

SABLE. On the medullary canal

of hair of - - - 270

On the structure of the hair of 279
SALAMANDER. Spermatozoa of • 183
SALIVA - ... 2OS

Amount of - - ib.

Mitscherlich's observations on - ib.

Solid constituents of - - ib.

Salts of - 209

Acetic acid in - ib.

Admixture of saliva with mucus ib.

Uses of - 210

SALIVARY glands - 407

Structure of - - - ib.

Follicles of - - - ib.

Form of, in embryo - - 408

SARCOLEMMA .... 337
SCANSORES. Spermatozoa of - 183

Page

SCARPA. On the presence of pig-
ment in the membranous
labyrinth of the ear of Mam-
malia - - 258
SCHERER. On pigment cells in

the bile - - - 211

SCHULTZ.

Observations on the action of
oxygen and carbonic acid on
the form of the blood cor-
puscles - - - 82. 84

Ditto of iodine on ditto - 116

SCHUMLANSKY. On the structure

of the kidney - 438

SCHVVANN.

On the membrane of the fat vesicle 224

On the nuclei of the fat vesicle 225

On the motion of the pig-
mentary granules in the cells
of the choroid - - 259

On the membrane lining the
cavities of true cartilage - 282

On the nature of bone cells - 310

On the tubular nerve fibre in
the early stages of its deve-
lopment ... 364
SEBACEOUS glands - - 398

Distribution of - 399

Secretion of - - - ib.

Cells of - - ib.

Structure of - - 400

SEQUIN. On the amount of fluid

passing off by the skin - 211

SEMEN - - 181

Characters of - - ib.

Spermatozoa - - 182

Pathology of semen - - 201

Application of a microscopical
examination of the semen to
legal medicine - 204

SHARPEY, Dr.

On the structure of the lamella
of bone - - - 298

On intra-membranous ossifica-
tion - 304

On the striated muscular fibrilla 341
SIDDALL. On the increased quan-
tities of white corpuscles in
the blood of the horse in
influenza - - 50

SIEBOLD.

On the absence of internal
organs in the spermatozoa - 189

On the development of sper-
matozoa - ib.

On living ditto in the uterus

. and fallopian tubes eight days
after connection - - ib.

INDEX.

567

Page
Smox, M.

Organic constituents of human
milk, according to - 153. 170

Analysis of sweat - -212

SIMON, Mr.

On the thymus - 10. 478, 479

On subacute inflammation of

the kidney - - 446

SIREN. Blood globules of - 67

Bone cells of - - 299

SKEY. On the size of muscular

fibres of the heart - - 338

SKIN. See Touch - - 491

SMELL - 500

Structure of mucous membrane
of nose - ib.

Tactile region - ib.

Epidermis of - - - ib.

Papilla of - ib.

Hairs of ib.

Sebaceous glands of - - 501

Pituitary region - - ib.

Epithelium of - ib.

Mucous follicles of - ib.

Blood-vessels of ib.

Olfactory region - - ib.

Position of - - - ib.

Characters of - - - ib.

Epithelium of - 502

Glands of - ib.

Pigment cells of - 503

Blood-vessels of ib.

Looped ditto of in foetus - ib.

Gelatinous nerve filaments of - ib.

Olfactory lobes - - ib.

Olfactory filaments - - 504

SPALLANZANI.

The discoverer of the white glo-
bules in the blood of sala-
manders - - 39

Experiments of, on frogs with
spermatised water - - 200

Sl'RRMATOPHORI - - -193

SPERMATOZOA - - - 182
Form of (in man, the rat, the
mouse, guinea-pig, in birds,
tritons, and salamanders) - ib.
Size of - 184
Structure of - - 185
Motions of - - 189
Mode of progression of - 1 90
Duration of motion of - 191
Effects of re-agents on - 192
Spermatophori - - 193
Development of - 195
Spermatozoa essential to fer-
tility - 198
Condition of, in hybrids - 1 99

Page

SPINAL CHORD, ganglion cells of- 358

SPLEEN - - 483

Structure of - - {&.

Capsule of - - ib.

Blood-vessels of ib.

Secreting structure of - - ib.

Dr. Jullien Evans on - - ib.

Dr. Jones on - - 485

Peculiar corpuscles in - - ib.

Lymphatics of- - 7

SOLIDS - - - 221

Fat - 222

Epithelium - 233

Epidermis - 247

Nails - - - - 253

Pigment cells - 257

Hair - 263

Cartilages - - - 281

Bone - - 294

Teeth- - 314

Cellular or fibrous tissue - 327

Muscle - 336

Nerves - 356

Glands - 388

SOLITARY GLANDS - - 367

Distribution of - - 397

Structure of - - - ib.

Orifices of - - ib.

Follicles of Lieberkuhun - ib.

SUPRA-RENAL CAPSULE - - 481

Structure of - - - ib.

Tubes of ib.

Molecules of - - - ib.

Granular nuclei of - 482

Parent cells of - ib.

Differences in medullary and

cortical portions of - - ib.
Vascular distribution in - ib.
Capsule of - - - ib.
STEATOZOON FOILICULORUM - 403
STOMACH TUBES - - 395
Arrangement of ib.
Form of - ib.
Structure of - - - ib.
Epithelium of ib.
Existence of in the duodenum - ib.
Modification of, near the pylorus 396
SUDORIFEROUS GLANDS. Distribu-
tion of - 424
Structure of - - 425
Tubes of ib.
Ducts of - ib.
Secreting cells of - - ib.
Number of - - 426
Structure of, according to Mr.

Rainey - - 549

SWEAT - - 211

Quantity of - - ib.

568

INDEX.

Solid constituents of -
Scales of epidermis in -
Analysis of -
Crystals in -
Pathology of -
SYNOVIAL FRINGES

Page

- 211

- 212

- ib.

- ib.

- 213

- 5-19

TASTE - - - - 494

Structure of mucous membrane

of tongue - ib.

Chorium of - - ib.

Papilla of - 495

Simple ... ib.

Compound - ib.

Filliform - - - 496

Fungiform - 497

Variety of ditto - - ib.

Calieiform •••-•'«• ib.

Foramen caecum - - ib.

Mucous follicles of - ib.

Epithelium of ib.

Filliform appendages of - 499

Gustatory region of - - 496

TEETH - - - - 314

General structure of - - ib.

Dentine - - - 315

Modifications of - ib.

Tubes of ib.

Secondary formation of, in cavity

of tooth - - - 316

Constitution of ib.

Ditto of, intertubular substance

according to Nasmyth - ib.

Ditto, according to Henle - ib.

Peculiar globular formation in - ib.

Cementum - - - 317

Bone cells of - - - ib.

Haversian canals of - ib.

Hexagonal layer of - ib.

Granular layer of - ib.

Dentinal tubes in - - 318

Cementum and dentine, modifi-
cations of each other - ib.

Enamel - ib.

Fibres of - - ib.

Cells of ib.

Form of ditto - ib.

Arrangement of ditto - - ib.

Pulp of tooth - -319

Structure of ditto - - ib.

Development of teeth - - ib.

General particulars of - - ib.

Formation of dentine - - 321

Dentine pulp - - ib.

Membrane of ditto - - 322

Formation of enamel - - 323

Enamel pulp - ib.

Cells of . - - ib.

Page

Formation of cementum - 324

Cementum pulp - ib.

Caries of the teeth - - 325

Tartar on ditto - 326

TESTIS - 475

Structure of - - - ib.

Tubes of ib.

Cells of 476

THORACIC DUCT - 4

Fluid of 7

Red colour of ib.

Composition of - ib.

Blood corpuscles in - ib.

Granular ditto in 8

THYMCS - 477

Follicles of - - - ib.

Structure of - - ib.

Limitary membrane of - 479

Lobular arrangement of - ib.

Blood-vessels of 477

Reservoir of - - - 4T8

Mucous membrane of - - ib.
Capsule of - - ib.

Blood-vessels in ib.

Milky fluid of follicles of - ib.
Granular and nucleated cells

of - - 10 and ib.

THYROID - - - 479

Vesicles of - - ib.

Structure of - - - 480

Lobules of - - - ib.

Blood-vessels of ib.

Nuclei and cells of - - 481

TODD and BOWMAN, Messrs. On

two forms of Haversian canals 297
Experiments on bone cells, sug-
gested by - - 300
Their opinion that the nuclei
of cartilage cells become de-
veloped into bone cells - 308
On the granular blastema in the

cancelli of bones - •- 309

On the nature of bone cells - 310
On the structure of white fibrous

tissue - 329
On the muscular structure of the

heart - 338
On " sarcous elements " - 34 1
On the nuclei of striated mus-
cular fibre - 342
On the striated muscular fibre- 343
On muscular contraction - 347
On the development of muscle 354
On the neui-olemma - - 360
On the occurrence of gelatinous
fibres in parts where their
nervous character is indu-
bitable - 363

INDEX.

569

_ Page
On the termination of nerves in

loops in the papillae of the

skin and tongue - - 368

On the epithelium of the stomach

cells - - - 394

On a modification of the follicles

and stomach tubes near the

pylorus - - - 396

Opinions as to the mucous glands 405
On the termination of the nerve

tubules in the papilla? of the

tongue - 492

On a fibrous structure in the

papillae of the tongue - 493

On the olfactory region - 501

On the olfactory filaments - 504
On the tubular structure of the

cornea proper - 508

On the anterior elastic lamina of

cornea - - 510

On the membrana pupillaris - 515
On certain elastic fibres attached

to the posterior elastic lamina ib.
On the granular layer of the re-
tina - 517
On a layer of cells situated on

the hyaloid membrane - 520

TOMES, Mr.

On the development of bone - 308
His lectures on teeth - - 316

Description of granular layer of

cementum - - 317

On the development of dentine 322
On the cells of the cementum pulp 324
On the spaces between the fibres

of newly-formed enamel - ib,

On tubes of carious dentine - 326

TONGUE. Structure of. See Taste 494

Ditto of frog - - - 70

TONSILLITIC glands - 404

TOUCH - - 491

Seat of ib.

Papilla; of - - - ib.

Epidermis of - - ib. 493, 494

Distribution of - 491

Arrangement of 492

Structure of - - ib.

Basement membrane of - ib.

Nuclear contents of - ib.

Blood-vessels of - - ib. 493

Nerves of - 492

Fibre? in - - 493

TOYNBEE.

On the structure of the Mal-

pighian body - 441

On the corpus Malpighianum - ib.
On the pathology of " Bright's

disease" ... 443

Page

TRACHEAL glands - 404

TRICHO-MONAS - - - 134

TURPIN.

His opinion that the milk glo-
bules consist of two vesicles
enclosing fine globules and
buttery oil - - 156

His idea that the fungus, penicil-
lum glaucum, was developed
from the milk globules - 179

VAGINAL glands - -'05
VALENTIN.

On the quantity of blood in the

system - 14

On the supposed stomach of

spermatozoa - 187

On the spermatozoa of the bear 188

On the development of sperma-
tozoa - - - 195

On the ciliated epithelium of the

ventricles - - - 242

On the occurrence of pigmentary
ramifications in the cervical

portion of the pia mater - 258

On the disposition of nucleated

or gelatinous nerve fibres - 362

On the termination of nerves in

the pulp of teeth - - 368

On the structure of the kidney 438
VALENTIN and, SCHWANN. Their
researches on the development

of muscular fibre - - 354

VIBRIOS, vaginal -- - - 1 35

Ditto venereal - - 150

VICUGNA, blood of - - 27

VILLI - ... 487

Of the intestines - - ib.

Distribution of ib.

Structure of - - - 488

Epithelium of - - ib.

Basement membrane of - ib.

Nuclear contents of - - 489

Oil-drops in - - - ib.

Blood-vessels of 49O

Lacteals of - - ib.

Peculiar form of - ib.

Of the pia mater - 537

VISION - - - 505

Structure of globe of the eye - ib.

Schlerotic, structure of- - ib.

Tunica albuginea of - - ib.

Vessels of - - ib.

Cornea - 506

Structure of - - - ib.

Laminae of - - - ib.

Conjunctival epithelium - ib.

Cornea proper - ib.

5/0

INDEX.

Page

Posterior elastic lamina - 509

Epithelium of aqueous humour ib.
Anterior elastic lamina - 510

Choroid - - - 511

Blood-vessels of ib.

Tunica Ryuschiana - - 512

Venae vorticosa? - - ib.

Stellate choroidal epithelium - ib.
Lamina fusca - - - 513

Hexagonal choroidal epithelium Ib.
Tapetum lucidivn - - ib.

Ciliary processes - 514

Secondary ciliary ditto - ib.

Zone of Zinn - - - ib.

Iris - - ib.

Uvea - - - - 515

Membrana pupillaris - - ib.

Retina - - -516

Tunica Jacobi - ib.

Granular layer - - 517

Ganglionary ditto - - ib.

Vesicular ditto - - 518

Fibrous grey ditto - - ib.

Vascular ditto - 519

Optic nerves - - ib.

Vitreous body - ib.

Vitreous humour - - ib.

Hyaloid membrane - - ib.

Crystalline lens - - 520

Capsule of - ib.

Body of - - ib.

Fibres of ib.

Structure and arrangement of

ditto - - 521

VOGEL.

His opinion that the mucous
corpuscles are formed exter-
nally to the blood-vessels - 130
Ditto as to the nature of pus

and mucous globules - 139

On the stellate bodies observed

on decomposing fat vesicles - 228
VOLKMAN and BIDDER. On the
origin of gelatinous filaments
from the ganglia of the sym-
pathetic - - 363

URINE - - 213

Specific gravity of - -214

Analysis of - - - ib.

Solid organic constituents of,
viz., mucous corpuscles and
epithelial scales - - ib.

Page

Spermatozoa in - - 215

Pathology of - - - ib.

UTERINE glands - - 405

UTERINE and FALLOPIAN TUBES

396. 404
Spheroidal epithelium of - ib.

WAGNER.

On the blood of the lamprey - 27

His belief in the existance of a
nucleus in the red blood disc 30

His opinion that the white glo-
bules are red blood corpuscles
in process of formation - 5:?

On the milk globules - - 1 59

On the structure of human sper-
matozoa - - 188

His supposition that the motions
of spermatozoa were produced
by a ciliary apparatus - 191

His observation of spermatozoa
in motion at the end of twenty-
four hours - - 192

On the development of sperma-
tozoa - - 195

On the degeneration of the testes
of birds during winter - 198

On spermatozoa in male hybrids 1 99

On the coloration of the iris of
birds - - 223

On the development of nerves - 371
WALLER, Dr. A. On the tongue

of the frog - - - 70

WILLIAMS, Dr. T. On the air cells

of the lungs - - 380

WILLIS. His translation of Wagner's

Physiology - - - 371

WILSON, Mr. Erasmus.

On the anatomy of epidermis - 253

On the structure of the striated
muscular fibrilla - 341

Calculation of the extent of the

sudoriferous system - - 426

WITHOFF. On the number of hairs
existing on different surfaces
of the body - - 274

YOUNG. His disbelief in the exist-
ance of a nucleus in the red
blood disc - - - 30

ZINN, zone of

- 514

THE END.

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