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Histology and Pathology.

By JOHN B. NICHOLS, M. D., Assist-
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HISTOLOGY AND

A MANUAL FOR STUDENTS AND PRACTITIONERS.

JOHN BENJAMIN NICHOLS, M.D.,

Demonstrator of Histology, Medical Department Columbian University,
Washington, D. C.,

AND

FRANK PALMER VALE, M. D.,

Assistant in Pathology, Medical Department University of Georgetown,
Washington, D. C.

SERIES EDITED BY

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Columbia University, New York; Visiting Surgeon, Bellevue Hospital, New York.

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PREFACE.

IT is the purpose of this work to present all the essential
facts relating to the normal histology and the pathological
anatomy and histology of man in a systematic and concise
way. In subjects so well established as these, originality
of data is little to be expected, and the chief object to be
aimed at is arrangement and treatment of the subject in a
manner convenient and clear to students and practitioners
of medicine, for whom this treatise is intended. It is
attempted to present the subject up to the most recent dis-
coveries and developments, avoiding points unsettled and in
doubt.

The part on normal histology is written entirely by Dr.
Nichols, that on pathology entirely by Dr. Yale. Each is
fully responsible for the statements in his own part, and for
those only.

J. B. NICHOLS.
FKANK P. VALE.
WASHINGTON, D. C.

180257

CONTENTS.

NORMAL HISTOLOGY.

CHAPTER I.

PAGE

INTRODUCTION 17

CHAPTER II.

CELLS AND EXTRA-CELLULAR ELEMENTS 22

CHAPTER III.
REPRODUCTION AND DEVELOPMENT 33

CHAPTER IV.
THE TISSUES 42

CHAPTER V.
GLANDS ; Mucous AND SEROUS MEMBRANES ; ORGANS 67

CHAPTER VI.
THE CIRCULATORY SYSTEM 75

CHAPTER VII.

THE LYMPHATIC SYSTEM 82

CHAPTER VIII.
BLOOD AND LYMPH 91

CHAPTER IX.

BLOOD-GLANDS AND DUCTLESS GLANDS 104

6 CONTENTS.

CHAPTEE X.

PAGE

THE ALIMENTARY SYSTEM Ill

CHAPTEK XL
THE RESPIRATORY SYSTEM 141

CHAPTER XII.
THE SKIN 151

CHAPTER XIII.
THE URINARY ORGANS 158

CHAPTER XIV.
THE REPRODUCTIVE SYSTEM 172

CHAPTER XV.
MUSCULAR AND SKELETAL STRUCTURES 198

CHAPTER XVI.
THE NERVOUS SYSTEM 202

PATHOLOGY.

INTRODUCTORY ...'.. 243

GENERAL PATHOLOGY.

CHAPTER I.
PATHOLOGY OF THE BLOOD AND CIRCULATION 247

CHAPTER II.
PATHOLOGY OP NUTRITION 274

CONTENTS. 7

SPECIAL PATHOLOGY.
CHAPTEK III.

PAGE

DISEASES OF THE BLOOD 309

CHAPTER IV.
DISEASES OF THE CIRCULATORY SYSTEM . . . . . . ... . . . . 318

CHAPTEK V.
DISEASES OF THE RESPIRATORY ORGANS . . . ,,. ., : 332

CHAPTER VI.
DISEASES OF THE GASTRO-JNTESTINAL TRACT 359

CHAPTER VII.

DISEASES OF THE URINARY ORGANS 403

CHAPTER VIII.

DISEASES OF THE NERVOUS SYSTEM .... . 420

NORMAL HISTOLOGY.

CHAPTER I.
INTRODUCTION.

Histology (from the Greek f<jroc, tissue, and ^0/07, discourse)
is a branch of anatomy treating of the minute or microscopi-
cal structure of living organisms. In its full significance it
relates to the entire organic kingdom, all plants and animals
alike. Within large classes of animals or plants the structure
of the tissues is quite uniform ; but on comparing one large
group of organic types with another, differences in the structure
appear, although there are a fundamental unity and similarity
throughout.

The histologic structure of man, with which the present
treatise deals, is substantially the same as that of all the mam-
malia, the points of variation being few and slight; hence
human histology and mammalian histology are almost identi-
cal. In passing to the classes of birds and reptiles, however,
marked differences begin to appear, as in the forms of the red
blood-corpuscles, while the general structure remains similar.

Analysis of histologic structures : In analyzing the organism
into its anatomic and histologic elements we find that they
are arranged in an ascending series of aggregations. The
ultimate elements of all are the atoms and molecules ; as the
scope of histologic science does not extend beyond the limits
of microscopic vision, the atomic and molecular structure of
tissues and cells does not come within its field, but is covered
by organic chemistry and physics, with different methods of
investigation.

The smallest elements with which histology deals are masses:

20 INTRODUCTION.

hence chemistry and physics cover the atomic and molecular
structure ; histology, the minute molar structure of organisms.

The ultimate and smallest perceptible histologic elements
of distinct individual character may be divided into two
classes, cells and non-cellular or extracellular elements. By
the union of these elements tissues are formed, as fibrous tis-
sue, muscular tissue ; by the union of tissues organs are
formed ; a combination of organs all working together for
the accomplishment of some general function constitutes a
system or tract, as the reproductive system, the alimentary
tract; while all the systems together make up the complete
organism.

The ascending grades of aggregation in organic structure
are, then, after atoms and molecules, cells and extracellular
elements, tissues, organs, systems, the organism.

The subject will here be elaborated in the order correspond-
ing to this analysis, beginning with the fundamental elements,
cells, etc., then taking up their aggregations in tissues, and
finally studying the structure of the organs making up the
various systems of organic activity.

Histologic technique : The histologic examination of tissues
is carried out entirely by microscopic methods. To gain an
adequate idea of histology, actual examination of the tissues
under the microscope is necessary. The use of the microscope
and the preparation of specimens of tissues for microscopic
examination involve numerous delicate procedures, the mastery
of which requires much special study and experience. Objects
cannot be examined in bulk under the microscope, but require
special treatment before their structure can be made visible.
For one thing they have to be very thin, so thin as to be
transparent; hence, solid tissues have to be cut into thin
slices, or sections, about yj-^th millimetre thick. In their
natural state most tissues are colorless, so that the details of
the structure cannot well be made out. To make the details
more visible it is customary to stain the sections with certain
dyes, of which a considerable number are available for vari-
ous purposes. Some stains have an affinity for some parts of
the tissues, other stains for other parts ; thus by the employ-
ment of various materials and methods different structures can
be brought plainly into view and differentiated. The nuclear

HJSTOLOGIC TECHNIQUE. 21

dyes, for instance, such as hsematoxylin, carmine, methylene-
blue, constitute a class of stains very much used, which
impart to the cell-nuclei a deep color, while they leave the
bodies of the cells uncolored ; the general stains, as eosin, on
the contrary, stain the cell-protoplasm, but not the nuclei.
There are numerous other processes to be carried out ; but the
limits of this work do not permit the consideration of practi-
cal methods, for which reference may be made to the numer-
ous special works on that subject.

CHAPTER II.
CELLS AND EXTRACELLULAR ELEMENTS.

Elements of tissues : The ultimate elements of which tissues
are composed are cells and extracellular (or intercellular) sub-
stances. Of these the cells comprise by far the bulk of the
tissues and play the chief part in the phenomena of life. The
body protoplasm, which is the seat and source of all vital
phenomena, is located in the cells.

The non-cellular elements, produced by the vital activities
of the cells, provide a connection, support, and framework for
the cells, which, composed as they are of semifluid protoplasm,
have little consistency of their own and are scarcely capable
of self-support. The cells are alive and the seat of life ; the
function of the extracellular elements is merely mechanical,
and they do not possess any real vitality of their own.

The cell : A cell is the smallest perceptible organization of
protoplasm having a definite and complete individuality, struct-
ure, and vitality of its own. It manifests in miniature all
the characteristics of life exhibited by the entire organism.
It is a unit of organic structure and organic activity. It is
the source and the seat of vital manifestations.

The name "cell" literally means a small inclosed space.
This meaning does not express a correct conception of the
nature of cells. The term arose from the fact that vegetable
cells, with their prominent walls and their transparent though
vital contents, appear like a mass of cavities separated by
partitions. The term "corpuscle," often used synonymously
with cell, better expresses the idea.

Classes of cells: All cells have a fundamental similarity in
origin, structure, and nature ; but as they actually occur they
vary much in form and function in different situations. Two
classes, in general, can be distinguished :

1 . Generalized or undijferentiated, independent, free-living
22

STRUCTURE OF CELLS. 23

cells, each endowed with all the attributes of vitality and
capable of complete existence singly and by itself. They are
typical cells. Of this kind are (a) the single cells of which
some of the lowest (unicellular) forms of living beings con-
sist, as the bacteria, desmids, and diatoms among plants ; and
the protozoa — amrebse, foraminifera, infusoria — among animals ;
(6) the ova and spores from which all the higher organisms
develop, each being an independent and undifferentiated cell,
and derived from the union of two other free though not typi-
cal cells, the female ovule and the male sperm-cell ; (c) cer-
tain actively vital cells living free in the fluids and tissues of
the highest organisms, exemplified by the white blood-corpuscle,
or leukocyte.

2. Differentiated or specialized cells. In unicellular animals
and plants the single cell carries on all the operations of life.
In the forms that through evolution have become more highly
developed, instead of a single cell the organism is composed
of many cells ; and instead of each cell in the multicellular
organism carrying on all the functions of life, those operations
are divided among different sets of cells, some serving one
purpose, some another. This is differentiation, or specializa-
tion ; it is a true division or organization of labor, and by it a
maximum result is accomplished with the minimum and most
economical expenditure of energy. In such a differentiated
organism the cells in various situations and devoted to various
purposes vary accordingly in form, structure, and function.
Each great class of plant and animal forms has its own char-
acteristic types of cells.

The specialized fixed cells of mammalian tissues may be in
general divided into four classes : epithelial cells, connective-
tissue cells, nerve-cells, and muscle-cells.

It is worthy of note that the young or embryonal forms of
cells that are specialized when mature often partake of the
more generalized character, thus exemplifying the principle
that the different phases through which an organism passes
in the course of its genesis and development are indicative
of the different forms through which its species passed in the
course of its evolution.

Structure of cells : All cells have a body of protoplasm,
which in most cases contains a nucleus (Fig. 1). The centra-

CELLS AND EXTRACELLULAR ELEMENTS.

FIG. 1.

Diagrammatic representation of an am-
reboid cell, showing the nucleus, nu-
clear reticulum, nucleolus, the cen-
trosome and attraction-sphere, the
spongioplasm, hyaloplasm, and pseu-
dopodia.

some is an important feature of most cells. Many cells are
surrounded by a cell-wall, while some have processes and other
special features.

The cell-body, or cytosome : As a general thing, the body or

main (non-nuclear) portion of
cells is composed of typical
and active protoplasm. The
protoplasm of cell-bodies is
often called cytoplasm. In typ-
ical cells, like the leukocyte,
two parts can be distinguished
in the protoplasm : the hyalo-
plasm, a clear, semifluid, motile
portion similar in appearance
to the white of an egg ; and the
granuloplasm, or spongioplasm.,
which in the living cell presents
a granular appearance, but is
supposed by many to be made
up of fibres or a sponge-like
reticulum. The granular portion usually occupies the central
portion of the cell, when it is called the endoplasm, or endo-
sarc ; the hyaline portion then forms the outer part of the
cell, and is called the ectoplasm, or ectosarc.

Sometimes the protoplasm contains granules, as of pigment,
or foreign particles which have been taken into the soft sub-
stance of the cell from without, as bacteria and other bodies
absorbed by leukocytes, or food- particles taken in by the
small unicellular organisms. Some cells contain vacuoles,
minute rounded cavities or spaces ; in some of the protozoa
these are contractile, being alternately distended with fluid
and then emptied by the contraction of the surrounding pro-
toplasm, thus accomplishing some sort of circulatory process;
certain human cells are vacuolated. Cells often contain sub-
stances elaborated by their own activity and stored up in
their bodies in granules or small masses. One of the com-
monest of these is fat ; cells, as in the liver, secreting mam-
mary gland, the vitelhis of the ovum, often contain small
fatty globules. In some cases, as in adipose tissue, this proc-
ess is carried to an extreme degree and the cell becomes com-

CELL-GRANULES. 25

pletely filled and distended with a solid mass of fat, the
original protoplasm remaining only as a thin atrophied shell.
In plant-cells the body of the cell is largely occupied by sap,
starch-granules, and the like. In some cases the protoplasm
becomes transformed, so that little vitality is left to the cell ;
as in the horny layer of the skin, in which the cells have been
converted into a tough horny substance well adapted to pur-
poses of protection.

Cell-granules : The granules which occur in the bodies of
many cells are of various kinds. Some are particles of pig-
ment produced by the action of the cell or absorbed from
without. Some are produced artificially by the reagents em-
ployed in the preparation of the specimen, not occurring in
the natural state ; even water will cause the appearance of
granules in some cells. Other granules, which are colorless,
appear to be specializations of the body-protoplasm. Among
such granules important distinctions are made out, especially
by their behavior with staining-reagents ; these distinctions
are especially serviceable in the study of leukocytes. Some
granules will become stained by one kind of dye, others by
another kind, these staining-peculiarities corresponding to dif-
ferences in the chemical constitution of the granules.

Stains in which the coloring-agent is the acid part of the
compound, as eosin, are called acid stains ; those in which the
basic portion of the dyestuff is the staining-principle, as
methylene-blne, are called basic stains; while stains composed
of a mixture of acid and basic dyes are called neutral stains.

Granules which are colored by neutral stains are called
" neutrophile " ; those that take basic stains are called " baso-
phile " ; those that take acid stains are best called " oxyphile "
f oc'JC, acid, and ydeco, to love), though they are most com-
monly called "eosinophile " (eosin being one of the most potent
acid stains), also sometimes " acidophile " (a barbarous term).

Ehrlich's much-quoted division of the granules of leuko-
cytes and other cells into five classes is as follows: ^.-granules,
coarse oxyphilic or eosinophilic granules, found in certain
human leukocytes; /2-granules, amphophilic granules (taking
both acid and basic stains), occurring in the blood of some
animals ; y-granules, coarse basophilic granules, found in mast-
cells ; ^-granules, fine basophilic granules, at times found in

26 CELLS AND EXTRACELLULAR ELEMENTS.

human leukocytes ; and e-granules, fine neutrophilic granules
(by some considered oxyphilic), very common in human leu-
kocytes.

The nucleus : Most cells contain in their interior a nucleus,
a rounded structure distinctly marked off from the cell-body.
It appears especially prominent when stained by nuclear and
basic dyes, which impart to the nucleus a deep color, while
the body of the cell is colored little or not at all. Nuclei are
inclosed and separated from the rest of the cell by a mem-
brane, the nuclear membrane. The nucleus consists of two
portions: the nuclear fibrils, or reticulum, a network of fibers;
and the nuclear matrix, a semifluid substance in the meshes
of the reticulum.

The fibrillar substance, again, is composed of two parts, a
homogeneous ground-substance called linin, supported in
which are granules, fibres, and filaments of a substance called
chromatin. In stained specimens the deep color shown by the
nucleus is taken by the chromatin (whence the name), while
the ground-substance, or limn, and the nuclear matrix are less
colored.

From the phenomena of karyokine&is, the chromatin is sup-
posed to be of the highest significance and importance in vital
phenomena, especially in connection with reproduction and
heredity. Chromatin has been conjectured to be identical
with nuclein, a chemical constituent of cells which is regarded
from physiological and chemical considerations as playing a
highly important part in the economy of cell-activity.

In many cases, as in ova and nerve-cells, the nucleus con-
tains a little nucleus of its own, or more than one, called the
nucleolns. Most cells are uninucleated, or contain but a single
nucleus each ; certain classes of cells, however, arc multinu-
cleated, containing several or numerous nuclei each, as the
voluntary muscle-cells, osteoclasts, and the giant cells present
in certain pathological processes.

In shape, the nuclei are usually spheroidal, oval, or discoid ;
but in different cases the shape varies greatly, and may be ex-
ceedingly irregular.

The location of the nuclei in the cells varies, being some-
times in (he centre, sometimes excentric, sometimes at the very
periphery of the cell.

CILIA AND FLAG ELL A. 27

Their size, in proportion to that of the entire cell, also
varies; usually the nucleus comprises but a small part of the
corpuscle ; but in some cases, as in the mononuclear leukocyte,
the nucleus occupies the largest part of the cell.

Most animal and vegetable cells are nucleated. Nuclei
have not been demonstrated in some of the unicellular organ-
isms, however, though they are probably present. Among
mammalian cells one important class, the red blood- corpuscles,
is not nucleated. The nucleus seems such an essential feat-
ure in the life and reproduction of cells that cells, like the red
blood-corpuscles, that are not nucleated are probably lacking
in the full attributes of vitality.

The precise function of the nucleus is not clear ; but it is
evidently of high importance, especially in connection with
reproduction and heredity. It is probably the most vital
part of the cell, the body largely serving nutritive and me-
chanical purposes.

The centrosome, or polar corpuscle, is a minute round re-
fractive body or point, situated in the interior of the cell.
The protoplasmic granules around it are arranged in delicate
radiating lines, forming the attraction-sphere. In resting or
non-dividing cells it may be within the nucleus, or just out-
side ; but in this stage it is not conspicuous and is usually in-
visible. During the process of karyokinetic cell-division it
appears prominently in the protoplasm of the cell-body, and
it plays an important part in this process, apparently exercis-
ing some sort of polar, or directive, or attractive influence in
the division.

The cell-wall, or cytolemma : Many cells are surrounded with
a covering or wall, which gives support and protection to the
soft protoplasm. This may be a distinct membrane, or a con-
densation and hardening of the outermost layer of protoplasm.
Some of the lower unicellular organisms secrete around them-
selves a silicious or calcareous covering. The cell-walls of
plants consist of cellulose, a firm substance belonging to the
starch group, to which the hardness of wood is due. Some
cells, as the leukocytes, appear to be devoid of a distinct cell-
wall.

Cilia and flagella : Certain kinds of cells have fine, hair-like
processes or filaments projecting from their surface, capable

28 CELLS AND EXTRACELLULAR ELEMENTS.

of active vibratory or undulatory movements. They are
composed of protoplasm like that of the cell-body, and their
motility is of the same nature as that of protoplasm generally.
When they are comparatively short and thickly crowded on
the surface, or a part of the surface, of the cell, they are called
cilia; when they are long and occur singly or only in small
numbers on the cell, they are called flagella. They occur not
only on low organisms, like bacteria and infusoria, but are of
wide distribution and great importance in the human body;
e. <?., where cilia occur extensively on ciliated epithelium, and
flagella on the spermatozoa.

The motion of cilia is vibratory, and, as they act in unison,
a wave-like motion results, which, acting from a fixed surface,
as in mammalia, carries particles along the surface or creates
currents in the fluids adjacent.

The motion of flagella is undulatory, and when attached to
free cells this movement rapidly propels the cells through the
fluid in which they occur, acting in the same manner as the
tail of a tadpole or fish. Flagella therefore are a means for
rapid locomotion of spermatozoa, monads, and other free-
swimming cells provided with them.

Other cell- processes : Besides motile processes like those just
described, some cells possess permanent and non-motile pro-
jections, which may be very various in form and size, coarse
or fine, long or short, branching or very irregular. Good ex-
amples are furnished by nerve-cells, bone-cells, connective-
tissue cells.

Forms of cells : Cells vary widely in shape, according to
the situation in which they occur and the purposes they serve.
The typical shape is perhaps spheroidal or oval. The leuko-
cytes, which are typical active cells, are spherical when at
rest. Many cells which when mature are of diverse shapes
are spheroidal when young. In a differentiated multicellular
organism there is a great diversity of form in different locali-
ties. On exposed surfaces they become flattened or disk-
shaped ; in other situations they are spheroidal, or columnar,
or elongated, or branching, sheath-like, or tubular, or alto-
gether irregular. But however diverse their form, their
fundamental type is identical throughout ; they are all definite
protoplasmic bodies, usually nucleated.

VITAL PROPERTIES AND FUNCTIONS OF CELLS. 29

Size of cells : The size of cells varies much. Some of the
bacteria are only about 1 micrornillimetre l in diameter ; these
are very small cells. The diameter of ordinary vegetable
cells ranges from 20 to 100 //; while some plant-cells are
fairly visible to the naked eye, nearly 1 mm. in diameter.
The mammalian ovum is a very large cell, about 0.2 mm.
(200 //) in diameter. Human red blood-corpuscles are about
7 or 8 IJL in diameter, and leukocytes 7 to 15 //. Human vol-
untary muscle-cells range from 10 to 40 fj. in diameter, and 2
to 4 cm. in length. The ordinary cells of human tissues
range from about 5 to 40 fj. in diameter.

Vital properties and functions of cells : The study of func-
tion pertains especially to the science of physiology ; in his-
tology it is, however, necessary to pay some regard to func-
tions, since function and structure are intimately related, and
a consideration of the former throws light on the latter, as a
full understanding of the latter is essential to an adequate
understanding of the former. The function expresses the
meaning of the structure.

The properties and manifestations of life and organisms in
general reside in the individual cells. The functions and ac-
tivities of cells are the same as those of life itself. These
activities are usually divided into three classes, nutrition, sensi-
bility, and motion.

Nutrition broadly comprehends the ingestion of food-ma-
terial ; its elaboration and assimilation into the organic struct-
ure ; the rejection of waste ; the formation of the structural
organization ; the preserving of it intact ; development to
maturity ; reproduction ; decline ; the passage through a
definite life-cycle.

Independent free-living cells, as the unicellular organisms,
leukocytes, etc., carry on all these vital operations alone —
nourish themselves through their life-cycle, manifest irri-
tability, and possess the power of quasi-spontaneous move-
ment. The specialized cells of differentiated organisms each
devote their respective energies to some particular part of the
work of life, instead of each performing all the vital functions.

xThe linear unit employed in microscopic measurements is the micro-
millimetre, or micron, briefly designated by the Greek letter /*; it is J^QQ th
of a millimetre, or about 2 sibo tn of an

30 CELLS AND EXTRACELLULAR ELEMENTS.

Thus the functions of such cells become distributed and dif-
ferentiated: one set of cells, in the muscular system, exercises
the power of contractility ; others, in the nervous system, are
specially arranged as seats of sensibility and consciousness ;
other cells have chemical functions, in the secretory appara-
tus ; some build up the framework of the body, some serve as
a covering to the surface, others provide for reproduction.

Movements of cells : The chief visible vital movements, of
automatic or quasi-spontaneous character, of which cells are
capable are: 1, amoeboid movement; 2, contraction; 3, cili-
ary movement ; 4, cyclosis, or internal circulation. These are
all probably varying manifestations of one fundamental mode
of motion. Besides these, a purely physical, not vital, micro-
scopic motion is sometimes observed in cells, namely, 5,
Brown ian movement.

Amoeboid movement : Many free cells, as the leukocytes in
the blood and some of the protozoa, possess the power of
spontaneously protruding and withdrawing processes of the
body-protoplasm. These processes are called pseudopod ia ;
and this kind of movement is called amoeboid, from the fact
that it is characteristic of the protozoon known as the amoeba.
At rest, the cells capable of amoeboid movement are usually
spheroidal ; but when in motion their shape may become very
irregular.

The pseudopodia have no definite forms or size, but are very
variable and irregular. They may be broad, or they may be
slender and filamentary ; they are always temporary and capa-
ble of retraction, unlike permanent cell-processes. By means
of them the cells are enabled to seize food-particles, or to
move themselves about, extending a pseudopodium in one
direction, and then by enlarging it the body gradually follows.

The hyaloplasm, or clear outer part of the protoplasm, is
the more actively concerned in the amoeboid movements ; it is
the first to be protruded in the pseudopodia, while the granu-
lar portion of the protoplasm more slowly follows. The
throwing out of the pseudopodia is said to be due to currents
of the fluid protoplasm, which, impinging on the periphery
of the cell, unbounded by a stiff wall, cause it to bulge and
protrude at that point.

Contraction is a mode of movement, closely allied to amce-

INTIMATE STRUCTURE OF CELLS. 31

bold movement, which is manifested by many cells. The
protoplasm surrounding contractile vacuoles exhibits it. It is
especially the function of muscle-cells, which decrease in
length and at the same time increase in thickness. This
movement is also said to be accomplished by the flowing of
the fluid protoplasm.

Ciliary movement : The vibratory movement of cilia and the
undulatory movements of flagella have been already described.
It is a vital protoplasmic movement.

Cyclosis : In certain vegetable cells currents of liquid and
minute particles are observable coursing about in definite
channels entirely within the cell. This movement is called
cyclosis, or internal cell-circulation, and is perhaps due to
spaces and channels in the cell-substance, along which the con-
tained fluid is forced by contractions of the protoplasm.

Brownian movement: Fine microscopic particles of solid
matter, if mixed with water or certain slightly viscid fluids,
exhibit under the microscope a characteristic constant dancing
or oscillating movement. This was first described in 1826,
by Robert Brown, from whom it has been called the Brownian
movement ; it is also called pedesis. Its cause is not under-
stood. It is a purely physical phenomenon, not vital ; but
granules within cells sometimes exhibit this movement.

Intimate structure of cells : The description of cells above
given covers the features observable by means of the micro-
scope. When we contemplate how from a single microscopic
cell, the ovum, a large organism can develop, composed of
millions of cells of a highly differentiated and vastly compli-
cated structure ; and how ova indistinguishable from one
another, though belonging to different species, produce their
own kind with unerring fidelity : we are forced to conclude that
the germ-cells must contain elements or mechanisms corre-
sponding to and capable of developing all the various parts of
the full grown organism — that is, that they have a vastly com-
plex structure that is hidden from us beyond the limits of micro-
scopic vision, and that what we see are but the coarsest feat-
ures of their construction. Structural elements not ordinarily
visible become manifest during karvokinesis. Between the
atomic and molecular structure of which we gain some idea
through chemical science, and the elements visible to us,

32 CELLS AND EXTRACELLULAR ELEMENTS.

there is in cells a large field of structural factors that is beyond
our powers of observation. If we could penetrate within this
invisible field, we might find much of histologic and structural
organization that would be of the greatest interest and im-
portance in explaining the mysteries of vital phenomena.
But we cannot as yet penetrate it, and the various vital struct-
ures and units which eminent biologists have assumed as
entering into the structure of cells, such as the hypothetical
pangenes, plasomes, plastidules, biophors, determinants, and
the like, have at present little more than a speculative value.

Extracellular elements: The non-cellular, intercellular, or
extracellular constituents of tissues serve to connect, support,
and provide a mechanical framework for the cells, which of
themselves do not possess the firmness requisite for a large
organism. These elements are not the seat of any real vitality,
which pertains exclusively to the cells ; they are produced by
the vital activities of the latter.

The intercellular substances exhibit considerable variety,
and in different tissues occur in varying proportions to the
total amount of the cells.

The simplest form is the intercellular cement, a scanty sub-
stance which cements cells together. The plasma of the blood
and the serum of lymph may be regarded as a fluid intercel-
lular substance in which the cells are suspended.

The greatest variety and quantity of extracellular elements
occur in the connective tissues, where the fibres, the hyaline
matrix of cartilage, and the mineral matter deposited in bones
are of this character.

CHAPTER III.

REPRODUCTION AND DEVELOPMENT.

Origin of cells : Every cell is produced by a preexisting cell
— omnis ceUula e celhila. A generation ago it was supposed
that under certain circumstances some of the lower organisms,
as the bacteria, could develop directly out of non-living mat-
ter. The generation of life de novo in such a manner was
called abiogenesis, or spontaneous generation. The incorrect-
ness of that supposition has been shown, and it is now uni-
versally believed that abiogenesis never occurs. Under all
circumstances life is always produced by preexisting life —
omne vivurn e vivo; all protoplasm is elaborated by preexisting
protoplasm.

Modes of reproduction of cells : There are several modes in
which cells reproduce themselves, namely : 1, direct division ;
2, budding, or gemmation ; 3, segmentation ; 4, indirect di-
vision, or karyokinesis.

FIG. 2.

Direct cell-division (Flemming).

Direct division : In this mode of cell-division a constriction
appears in the nucleus and in the cell-body ; this constriction
gradually deepens, until the two parts become completely

3— Hist. 33

34 REPRODUCTION AND DEVELOPMENT.

separated, and the one parent-cell has become two daughter-
cells. This process is called direct or amitotic division or
fission (Fig. 2). This method of division sometimes occurs
with some cells, but it is believed to be far less common than
the indirect or karyokinetic method.

Budding, or gemination: Occasionally this mode of cell-
reproduction occurs among the protozoa. A small protrusion
of protoplasm appears at the margin of the cell, gradually
enlarges, and is finally separated from the parent and becomes
independent.

Segmentation : This consists in the simultaneous breaking
up of the parent-cell into a number of small rounded cells,
which separate, and in their turn develop to maturity. It
occurs among some protozoa, and in human medicine is easily
observed in the parasite of malaria, which at the end of its
life-period rather abruptly breaks up into from eight to twenty
minute hyaline spheres.

Indirect division, karyokinesis, or mitosis, is the usual and
chief mode by which all cells reproduce themselves. The
process is accomplished by a series of definite changes, affect-
ing especially the chromatin-filaments and centrosomes (Figs.
3-8.) The stages of typical karyokinesis may for purposes
of description be capitulated as follows :

1. Resting stage.

2. Continuous convolution/ "> c!ose s,ke.in'

{ 6, open skein.

3. Segmented convolution.

4. Equatorial or aster stage.

5. Division of chromosomes and metakinesis.

6. Diaster stage.

7. Double segmented convolution.

8. Double continuous convolution.

9. Division of cell-body.
10. Resting stage.

In the intervals between karyokinetic division, or the rest-
ing stagef the chromatin of the nucleus is arranged in gran-
ules, filaments, or a network, but not in any definite manner.

The mitotic process begins with an enlargement of the
nucleus and an increase of the chromatin ; at the same time
the centrosome appears in the body- protoplasm and enlarges.

KAR YOKINESIS.
FIG. 3. FIG. 4.

Continuous convolution.
FIG. 5.

Metakinesis, earlier stage.

FIG. 7.

Equatorial or aster stage.
FIG. 6.

Metakinesis, later stage.
FIG. 8.

Diaster stage. Double segmented convolution.

Diagrammatic representation of stages of karyokinesis (Flemming).

36 REPRODUCTION AND DEVELOPMENT.

The chromatin develops into an apparently continuous and
single long filament in a tangled skein, or dense convolution, or
" spirem." This is the stage of the continuous convolution. At
first the chromatin-filament is fine, and is arranged in close,
crowded turns ; this formation is called the close skein. Later,
the filament becomes coarser, and the loops and windings of
the convolution more open, forming the open skein. The
nuclear membrane and nucleoli become gradually transformed
into the chromatin-filament and absorbed into the skein, and
thus disappear, so that no wall now separates the nucleus from
the cell-body.

The chromatin-filament, which heretofore has apparently
been one continuous thread, then breaks up into segments,
forming the segmented convolution. Each of these segments is
called a chromosome. The chromosomes form V-shaped or
U-shaped loops, and tend to arrange themselves with the

FIG. 9.

Cell (ovum of ascaris megalocephalus) undergoing karyokinetic division (Kostanecki
and Siedlecki). a, centrosome ; b, chromosomes.

angles toward a common centre and the arms radiating out-
ward. The number of chromosomes in different species is
usually from four to thirty-six in each cell ; one crustacean,
artemia, has 168. Human cells contain about sixteen chromo-
somes each. The number of chromosomes is uniform in all
the cells of the same species. In the meantime, during the

INDIRECT DIVISION. 37

segmentation of the spirem, the centrosome has divided into
two, which have separated and become located at opposite
points or poles, one on each side of the nucleus.

In the equatorial or aster stage the process is at its height.
The achromatic spindle has developed, consisting of delicate
striae, uncolored by the stain (whence the term achromatic),
which are arranged in the form of two cones having their
apices in the two centrosomes, and their bases directed toward
each other ; or, in other words, the achromatin-fibres form a
fusiform spindle, with the extremities in the centrosomes or
poles (Fig. 9). The chromosomes become arranged in the
equatorial plane of this spindle — that is, in the plane bisect-
ing at right angles the axis or line connecting the two poles ;
their loops are directed inward toward the common centre;
their arms and free extremities extend outward in a radiating
manner, presenting the appearance, from the side, of a star,
or aster.

The next stage is the division of the chromosomes and migra-
tion of their segments, or metakinesis. The chromosome-fila-
ments split in two longitudinally, beginning at the apex or
bend, and the apices of the separated halves then travel along
the threads of the achromatic spindle toward the two cen-
trosomes.

Thus the double aster or diaster stage develops. Around
each centrosome the daughter-chromosomes become arranged
in radiating or the aster form. The chromatin of the single
original nucleus has been divided into two equal parts, to
form two new da lighter- nuclei ; and it is to be observed that
the number of chromosomes in the daughter-cells is precisely
the same as in the parent-cell, and remains constant through-
out for each species.

The free ends of the chromosome-fibers become connected
by achromatic filaments, and the chromatin-fibers now undergo
a change precisely the reverse of that of developing karyo-
kinesis. The double segmented convolution, or disconnected
chromosomes, is succeeded by the double continuous convolu-
tion: first the open skein appearing, then the close skein.
The nuclear membrane and nucleoli appear, and ultimately
the nuclei resume the condition of the resting stage. Simul-
taneous with these retrograde processes in the nuclei, division

38 REPRODUCTION AND DEVELOPMENT.

of the cell-body occurs ; the body has become indented, a line
of cleavage has appeared across it, and it divides entirely into
two parts. Thus the original cell has divided into two cells,
each like the parent in all respects.

Conjugation : In contrast to the division of one cell into two,
the contrary process occurs, namely, the coalescence of two
cells to form one. This is called conjugation. It is observed
among some of the protozoa, two of these organisms becoming
completely fused to form one individual. A form of conju-
gation also occurs throughout the greater part of the entire
animal and plant kingdoms in connection with sexual repro-
duction. The fusion of the female and male gerrn-cells, the
ovum and spermatozoon in animals, the ovule and pollen in
plants, is a case of conjugation, although here the uniting cells
are somewhat different from each other. This form of conjuga-
tion is evidently of profound significance in the vital economy,
though not well understood. Even in the protozoa conjuga-
tion is perhaps connected with reproduction.

Sexual reproduction : Multicellular animals are developed
from a female and a male cell, which coalesce and form a
single cell, the fecundated ovum. The spores from which
cryptogamous plants develop are likewise fertilized single
cells. Phenogamous plants are developed in essentially the
same way ; the fully formed seeds are, however, multicellu-
lar, though they can be traced back to a single fertilized ovule-
cell. The female element before fecundation is termed the
ovule; after union with the male element it becomes the ovum.
The male elements in animals are the spermatozoa ; in flow-
ering plants, the pollen.

The ovule : The mammalian ovule, as fully developed in
the female ovary, is a comparatively large spherical cell about
0.2 millimetre in diameter. It is surrounded by a delicate
membranous wall, the vitelline membrane. The body of the
cell consists of protoplasm infiltrated with a large number of
minute fat-globules, for the early nourishment of the develop-
ing embryo ; this is the vitellus, or yolk. Within the vitellus,
located excentrically, is the nucleus of the cell, or the germi-
nal vesicle ; within this, again, is the nucleolus, or germinal
spot.

Maturation of the ovule : Before or while the ovule receives

FERTILIZATION OF THE OVUM. 39

the male element it undergoes certain changes, called matura-
tion. The nucleus of the ovule divides and gives off a portion
of its substance, which forms a small body, the polar body,
which proceeds to the surface of the cell and is there ex-
truded. This process is repeated, a second polar body being
given off from the nucleus and expelled from the cell in the

FIG. 10.

Maturing ovum of physa (fresh-water snail) (Kostanecki and Wierzejski). Above
is the first polar body extruded from the ovule and dividing into two bodies.
Just beneath it is the nucleus of the ovule, dividing to form the second polar
body. At the centre of the ovule is the male pronucleus with its centrosome
and attraction-sphere, derived from the spermatozoon.

same way. By this process the nucleus is " reduced/' or
divested of a portion of its chromatin, so that when the chro-
matin of the spermatozoon, also reduced, is united with it the
number of chromosomes normal to the cells of the species is
present. The portion of the original nucleus now remaining
in the ovule is called the female pronucleus.

Fertilization of the ovum: The ovule is not capable of under-

40 REPRODUCTION AND DEVELOPMENT.

going further development until the male element, or sperm-cell,
is added to it. This process is called the fertilization, impreg-
nation, or fecundation of the ovum. During or after the proc-
ess of maturation the spermatozoon finds its way to the surface
of the ovule, passes through the vitelline membrane, or through
a small opening in it called the micropyle, and enters the proto-
plasm, where it forms a nucleus, the male pronudeus (Fig. 10).
The male and female pronuclei then coalesce, or at least be-
come apposed, and temporarily disappear, reappearing when
the cell undergoes division. The ovum is now fully formed
and capable of further development. It is a typical cell,
endowed potentially with all the attributes of vitality, and
contains within its minute compass almost inconceivable pow-
ers of definite and intricate expansion and evolution. It
might seem at first view that the largest part of the substance
of the fertilized ovum was contributed by the female parent,
while the contribution of the male was comparatively insig-
nificant ; but of the really vital substance, the chromatin, the
male element furnishes as much as the female, and hence makes
an equal impression on the offspring. To explain the ina-
bility of the unimpregnated female ovule to undergo division,
it has been suggested that it has no centrosome, and that this
is supplied by the spermatozoon, the addition of which there-
fore supplies all the conditions necessary for division.

Development of the embryo : The further development of
the embryo proceeds by mitotic cell-division. The ovum
divides into two cells ; each of these into two more, and so
on. Thus a mass of cells is formed, constituting the blasto-
derm. Soon the cells of the blastoderm develop so as to
form two layers, the outer being called the epiblast, the in-
ner the hypoblast. Later another layer of cells appears
between these two, and is called the mesoblast. Up to a cer-
tain point the cells produced by repeated cleavage are similar
to one another ; but afterward differences of form and purpose
appear in different situations according to the organs and tis-
sues into which they are about to develop. This development
of cells having similar origins into dissimilar cells is the proc-
ess of differentiation. By the continued production and dif-
ferentiation of the cells of the epiblast, hypoblast, and meso-
blast, the embryo develops, and the various organs gradually

DEVELOPMENT OF THE EMBRYO. 41

come into existence. The details of this process it is the
province of the science of embryology to consider.

Well-defined tracts of the adult body may be traced back to
the three primary blastodermic layers, and the distinctions of
origin thus made are commonly emphasized as of importance.
Without entering into minutiae, the tissues derived from the
primary layers are in general as follows :

From the epiblast are derived the epithelium of the epider-
mis ; the nerve-centres and axis-cylinders, and the enamel of
the teeth.

From the hypoblast is derived the epithelium of the mucous
membranes lining the alimentary and respiratory tracts and
bladder, and of the glands tributary thereto.

From the mesoblast are derived the corium of the skin and
the tunica propria of mucous membranes ; the connective-tissue
structures ; cartilage, bone, the vascular and lymphatic sys-
tems, the blood, the muscular tissues, the reproductive organs,
and the kidneys and ureters.

CHAPTER IV.

THE TISSUES.

Classes of tissues : Cells and intercellular elements make
up tissues ; tissues make up organs. A full knowledge of the
different varieties of tissues is essential to an adequate and
easy understanding of the structure of organs. The simple
tissues of the human body may be divided into five classes :

Epithelium and endothelium ;

Connective tissue ;

Muscle ;

Nerve-tissue ;

Free cells and body-fluids.

Of these the first four are made up of fixed elements ; the
last comprises the free and fluid parts of the organism. These
classes are sharply distinguished from one another by morpho-
logical and functional characters and by the fact that each
class, in general, is developed from and in turn produces its
own kind of cell and tissue exclusively.

Endothelium and Epithelium.

Location : The cells lining the exposed surfaces of the body
form the class of epithelium and endothelium.

Those lining the closed internal cavities, as the vessels and
serous sacs, and derived from the mesoblast, are called endo-
thelial cells.

Those lining the " external " surface of the body and the
channels and tracts continuous with it (that is, those lining the
skin, mucous membranes, and tributary glands), also the
closed thyroid and other ductless glands, central canal of the
spinal cord, and ventricles of the brain, are called epithelium.

Epithelium consists almost entirely of cells, there being only
a slight amount of intercellular substance to cement them to-
gether. It is derived from the epiblast and hypoblast, except

STRATIFIED SQVAMOUS EPITHELIUM.

the epithelium of the kidneys, ureters, and sexual organs,
which is mostly of mesoblastic origin.

Its function is, over large areas, protective ; in the glands
it is secretory ; in some tracts, as the intestine, it is not only
protective, but has absorbent functions; while ciliated and
other epithelium serve special purposes.

Varieties of epithelium: Epithelium-cells may be divided
into the following classes : squamous, columnar, ciliated, gob-
let, glandular, and specialized epithelium. Some of these,
again, are divisible into simple epithelium, in which the cells
form a single layer; and stratified, in which they are arranged
in several layers.

Simple squamous epithelium : Squamous epithelium-cells are
large, thin, flat, disc-shaped cells, each with a large discoid
nucleus. In simple squamous epithelium the cells form but
a single layer, and meet edge to edge. It is not extensively
distributed, occurring in the alveoli of the lungs, the capsule
of the Malpighian bodies of the kidney, and a few other situa-
tions. Endothelium is very similar to it.

FIG. 11.

Stratified squamous epithelium, oesophagus of rabbit (Dunham), a, deeper layers
of rounded germinal cells ; b, more superficial layers of flattened cells ; c, sur-
face layer of horny cells ; d, underlying fibrous tissue ; e, papillary projection
from the fibrous layer.

In stratified squamous epithelium the cells form several
layers (Fig. 11). Those on the surface are flattened and
squamous, overlapping one another at the edges. The cells
of the lower layers are cuboidal or spheroidal ; they become

44 THE TISSUES.

gradually flattened toward the surface, and are germinal cells
which ultimately become squamous. This variety is of exten-
sive distribution, forming the epidermis of the skin and the
epithelial layer of the conjunctiva, mouth, part of the pharynx
and larynx, oesophagus, vagina, and portions of the urethra.

The 'epithelium lining the bladder, ureters, and pelvis of
the kidneys is a variety of stratified squamous epithelium
sometimes called transitional epithelium (Fig. 12). The num-
ber of layers of cells is few, forming a sort of intermediate

FJG. 12.

Transitional epithelium, bladder of mouse (Dogiel).

or transitional variety between the simple and stratified types.
The lower cells become quickly changed into the flattened
surface cells.

Columnar epithelium — non-ciliated: Columnar epithelium-
cells are elongated, columnar, or prismatic in shape, arranged
on a basement-membrane perpendicular to it, with one end di-
rected outward. Sometimes they are shorter and more
cuboidal.

When they form a single layer they constitute simple col-
umnar epithelium (Fig. 13), which occurs throughout the
stomach and intestine, in some gland-ducts, covering the ovary,
and in portions of the male urethra and seminal tracts.

Non-ciliated stratified columnar epithelium, in which the cells

GLANDULAR EPITHELIUM.

are in several layers (the outer only being columnar), occurs
in the olfactory nasal membrane and a portion of the vas
deferens.

Columnar epithelium — ciliated : A variety of epithelium in

FIG. 13.

Simple columnar epithelium and goblet cells, from the intestine, Shows the stri-
ated free cuticular margin of the cells in this situation.

which the exposed surfaces or ends of the cells are covered
with cilia, which in life are in characteristic wave-like motion.

Simple ciliated epithelium occurs in the Fallopian tubes,
uterus, central canal of the spinal cord, and brain ventricles.

In stratified ciliated epithelium (Fig. 14) the cells form seve-
ral layers. Only those of the outer layer are columnar and
ciliated ; those of the lower
layers, the germinal cells, are FIG. 14.

rounded or pear-shaped, be-
low and between the columnar
cells, into which they ulti-
mately develop. This variety
covers the respiratory tract,
Eustachian tubes, and epidid-
ymis.

Goblet epithelium-cells (Fig.
13) are large elliptical or pyri-
form cells, with their larger ciliatedcolumnar epithelium (stratified))

ends outward and their nuclei from trachea, showing ciliary wave.

near their bases. They occur

scattered among columnar epithelium-cells. Their bodies
have a clear unstained, distended appearance, being filled with
a mucinous substance which they secrete and discharge on the
surface of the mucous membrane.

Glandular epithelium is that which forms the secreting

46 THE TISSUES.

portion of glands. The cells are in general spheroidal or
polyhedral, but vary in shape in different situations.

Specialized epithelium : In some situations epithelium-cells
become modified in various ways different from those above
mentioned, as the pigmented epithelium of the retina and else-
where, and the so-called neuro-epithdmm occurring in certain
sensory organs, the retina, ear, tongue, and olfactory mem-
brane.

Endothelium : The closed internal cavities of the body —
the vascular channels, serous cavities (as the pleura, peri-
toneum, and pericardium), synovial membranes, and lymph-
spaces — are lined with endothelium (Fig. 15). Endothelium

FIG. 15.

.-,•

Endothelial lining of small vein and capillary (Engelmann).

is distinguished from epithelium mainly in being of meso-
blastic origin. Morphologically it is similar to simple
squamous epithelium, consisting of a single layer of polygonal
flat nucleated cells, smooth and shiny, which meet edge to
edge by oftentimes sinuous or serrated margins. Endothelium-
cells merge into the flattened type of connective-tissue cells,
with which they are genetically related.

CONNECTIVE TISSUE. 47

Connective Tissue.

Connective tissue is distributed everywhere throughout the
body beneath the outer epithelial layer. It forms a support-
ing and connecting framework for the parts of the organism,
and to this end it envelops and penetrates all the interior
organs and structures. It permeates the organism so com-
pletely that if all the other tissues were removed the connec-
tive-tissue framework would still form a complete mould of
the body and its organs. It originates from the mesoblast,
except the neuroglia of the nerve-centres, which is epiblastic.
Like other tissues, it is made up of cells and non-cellular
elements, but is peculiar in that the non-cellular portions
largely predominate, as naturally follows from their constitut-
ing the main framework of the body.

The connective-tissue cells, while differing in various situa-
tions, have a fundamental morphological and genetic simi-
larity.

The extracellular elements serve mechanical purposes, and
are not endowed with vitality ; they are produced by the
connective-tissue cells. The most specialized and generally
distributed of the extracellular elements are certain fibres,
which are of two kinds, white fibres and yellow elastic fibres.
Other intercellular materials are an interstitial mucinous or
gelatinous substance especially found in young connective
tissues (as mucous tissue), the matrix of hyaline cartilage,
and the mineral matter in bone.

Connective -tissue cells are of one general type, though
varying much in different situations. The forms associated
with fibrous tissues are sometimes called "fibroblasts."
Connective-tissue cells are sometimes round or spherical,
small and prominently nucleated ; such cells occur only in
young, growing, or embryonal forms of connective tissues.

The mucous cell is another form of young or embryonal
connective-tissue cell ; it is a fiat nucleated cell of irregular
stellate shape, with its pointed processes, three or four in
number, prolonged into fine filaments which anastomose with
similar processes from neighboring cells.

In some situations, especially in fibrous tissues, the connec-
tive-tissue cells are fusiform in shape ; in some they are
stellate ; in others, as in basement-membranes and the cells

THE TISSUES.

lining retiform tissue and lymph-spaces, they are flattened like
endothelium, with which they are closely related ; sometimes
they are lamellar, as in tendon-cells ; or they may -be altogether
irregular.

In general, connective-tissue cells are small flattened or
elongated cells, with prominent nuclei and relatively small
bodies, and often wirh processes ; they are polymorphous and
adaptable to the situations in which they are placed. Some-
times they are pigmented, such cells, stellate or irregular,
occurring in the choroid, pia mater, and in amphibia.
Some connective-tissue cells are granular, as precursors of fat-
cells.

Fat-cells are large spherical connective-tissue cells distended
with fat. Odontoblasts, cartilage-cells, and bone-cells are
forms of connective-tissue cells, and neuroglia-cells differ
chiefly in their epiblastic origin.
Plasma-cells occurring in areo- FIG. 17.

lar tissue contain numerous
vacuoles and vary in form.

Mast-cells are large cells

FIG. 16.

White fibres, teased to show indi-
vidual nbrillse (Dunham).

Yellow elastic fibres from subcutane-
ous areolar tissue (Schafer).

twenty to thirty micromillimetres in diameter, containing
coarse basophile (y) granules, and irregular pale-staining
nuclei ; they are occasionally found in areolar tissue.

MUCOUS TISSUE. 49

Wandering cells, cells which are free and capable of moving
about in areolar tissue, are really leukocytes or lymph- eel Is,
and belong to the class of free cells.

The white fibres consist of very fine colorless fibrillae
cemented together in coarser fibres (Fig. 16). They may be
arranged in an interlacing network or parallel in bundles, and
often present a wavy appearance. The fibrils do not branch.
They swell and become indistinct when treated with acetic
acid, often showing constrictions. They yield gelatin on
boiling. They are characterized by unyielding strength, and
occur in tendons, ligaments, etc., where tenacity and firmness
are required.

The yellow elastic fibres (Fig. 17) are yellowish, highly
refractive, branching fibres, fine or coarse, forming bundles or
membranous interlacing networks. They yield elastin, not
gelatin, and stain differentially with orcein. When divided, the
freed ends curl up. They are characterized by elasticity, and
are widely distributed, occurring in especial abundance in the
ligamentum nuchae of animals, ligamenta subflava, blood-
vessels, and in yellow elastic cartilage.

Two theories are held as to the development of the fibres,
white and yellow : one is that they are produced by a
transformation of the protoplasm of the connective-tissue
cells ; the other, probably more generally true, is that they
are not transformed cells, but develop in the mucinous inter-
cellular matrix by a sort of secretory process, under the
agency of the cells.

Varieties of connective tissues: According to the varving
forms and proportions of the constituent elements, there are
many varieties of connective tissues, merging imperceptibly
into one another without sharp dividing lines. The following
best-marked types may be mentioned :

Mucous tissue; Tendons; *

Areolar tissue ; Retiform tissue ;

White fibrous tissue ; Cartilage ;

Yellow elastic tissue ; Bone ;

Membranes ; Dentine ;

Adipose tissue ; Neuroglia.

Mucous tissue (Fig. 18) consists of mucous cells, flattened

4— Hist.

THE TISSUES.

stellate cells with fine anastomosing processes, forming an
open reticulum, the meshes of which are filled with a semi-
fluid mucinous matrix. It is a soft gelatinous tissue. It is
an embryonal or early stage of connective tissue, becoming
later more firm by the development of fibres in the intercel-
lular substance. It occurs in the umbilical cord and other

FIG. 18.

if ^'-ir *r&> -^m t

Mucous or embryonic connective tissue (Bohm and Davidoff ).

situations in the early embryo, but in the adult only in the
vitreous body of the eye and in mucous tumors.

Areolar tissue (often somewhat ambiguously called "cellular
tissue ") is unloose network of white and yellow fibres con-
taining connective-tissue cells, fat-cells, wandering cells, and
blood and^ymphatic vessels (Fig. 19.) The open spaces, or
areolse (whence the name of the tissue), are filled with lymph.
It is a loose delicate shining tissue, widely distributed, found
ecially beneath the skin and mucous membranes, and
pjjrts to move somewhat upon each other.
of one or another constituent it passes

YELLOW ELASTIC TISSUE.

gradually into fibrous, adipose, or other varieties of connec-
tive tissue.

White fibrous tissue is that in which the white fibres pre-
dominate, forming a tough, dense, inelastic tissue. Connec-
tive-tissue cells, fusiform, or flat and clasping the fibrous
fasciculi, are scattered among the wavy fibres, more numerous

FIG. 19.

Subcutaneous areolar tissue, from rabbit, showing white and elastic fibres and
connective-tissue cells (Schafer). c, developing fusiform and stellate cells;
c', flattened cell ; /, elongated cell ; g, wandering cell ; p, plasma-cells.

when the tissue is young, less numerous or even almost
absent in old tissues. It is widely distributed, forming tough
fascia?, aponeuroses, ligaments, capsules and trabeculse of
organs, and the like.

Yellow elastic tissue is that in which elastic fibres predomi-
nate, as in the ligamenta subflava and bloodvessels, structures
characterized by elasticity and resiliency. The l*gamentum
nuchae of certain animals consists mainly of coarse. polygonal
yellow fibres, with a few scattered white fibres or cells.
Arteries contain much elastic tissue, largely in the form of
elastic plates, fibrous networks, or perforated membranes.

Membranes: Connective tissue often forms distinct mem-

THE TISSUES.

FIG. 20.

branes, as in the capsules surrounding organs and the corium
of the skin. These are often fibrous tissue, made up of inter-
lacing fibers ; in other cases, especially in the basement-mem-
branes which support epithelium, they consist of flattened
connective-tissue cells joined edge to edge in a single layer.

Adipose or fatty tissue (Fig. 20) occurs in large masses
under the skin, in the omentum, about the viscera, especially
the kidneys and heart, and elsewhere. The cells are large,

distended spheres of fat, which
has been accumulated in the
cell-body until the original pro-
toplasm has been compressed
into a thin atrophied membrane
enveloping the fat, and the
nucleus has been pushed out into
the periphery. The cells are
spherical in shape, and are
packed together in masses, with
inconspicuous fibres between.
Fatty tissue merges into areolar
tissue in which the connective-
tissue cells become filled with
fat and crowded together.

Retiform tissue (Fig. 21) con-
sists of a reticulum of fine interlacing fibres, covered, espe-
cially at the intersections, with flat stellate endothelioid con-
nective-tissue cells. This tissue forms the framework of lym-
phoid or adenoid tis&ue, as in lymph-follicles and glands, in
which the open spaces of the reticulum are filled with lymph
and lymphoid corpuscles, which crowrd the meshes and obscure
the network ; these lymphoid corpuscles belong to the class
of free cells and are not fixed in the spaces. The framework
of the spleen is of a similar character. Retiform tissue may
be regarded as an open sustentacular tissue for containing
lymph-corpuscles and lymph. The term "retiform" as here
used applies only to the connective-tissue framework, and is
not taken to include the lymph-corpuscles or as a synonym of
lymphoid tissue.

Cartilage is a specialized form of connective tissue consist-
ing of cartilage-cells, which are modified connective-tissue

Adipose tissue. Crystals of fatty
acids are represented in two of
the cells.

HYALINE CARTILAGE.

cells, imbedded in an abundant matrix. .According to the
nature of the matrix, cartilage is of four kinds, hyaline carti-

FIG. 21.

Retiform tissue (Ribbert).

lage, white fibro-cartilage, yellow elastic cartilage, and cellu-
lar cartilage.

FIG. 22.

Hyaline cartilage.

Hyaline cartilage (Fig. 22) occurs in the costal cartilages,
the articular ends of bones, the nasal cartilaginous septum,

THE TISSUES.

the larger cartilages of the larynx, the trachea and bronchi,
and in the embryo is the precursor of most of the bones. The
cells are prominent and rounded, with large nuclei and dis-
tinct capsules, and are imbedded in an apparently homogeneous,
hyaline, tough matrix, which yields chondrin. Instead of
being really homogeneous, the matrix is said to have a delicate
fibrillar structure. The means or channels by which nutrient
fluids can penetrate to the interior of hyaline cartilage for its
nutrition are not known. The cartilage-cells divide in two
within the capsule of the parent-cell, which is thus as it were
cast off, and each daughter-cell then acquires a new capsule.
By the repetition of this process t\vo or three generations of
cells may sometimes be found within the remains of the cast-
off capsule of the single original parent-cell. The capsules
thus cast off are gradually transformed into the matrix, which
is partly developed in this way. The ground-substance near
the cells stains differently from that more remote. Owing to
their mode of division the cells in costal cartilage tend to
occur in groups ; in articular cartilage they form rows perpen-
dicular to the surface.

Some of the cartilages are surrounded by a fibrous mem-
brane, the perichondrium j containing fusiform or flattened con-
nective-tissue cells. The lowermost of these cells take on the
characters of cartilage-cells, become thicker and more rounded,
and the edge of the cartilage shows a gradual transition from
these cells to the typical cartilage-cells in the interior. In
this manner the cartilage is produced or grows from the lower
layer of the perichondrium.

FTO. 23.

Fibro-cartilage, from human inter vertebral disc (Schaferj.

White fibre-cartilage (Fig. 23) forms the intervertebral discs
and other cartilages entering into the construction of certain

CELLULAR CARTILAGE.

joints. It consists of a dense white fibrous matrix in which
cartilage-cells are imbedded. According to the character of
the cells, it exhibits all gradations to ordinary white fibrous
tissue.

Yellow elastic cartilage (Fig. 24) occurs in the auricles,
Eustachian tubes, epiglottis, portions of the arytenoid carti-
lages, and the small cartilaginous bodies near the latter. It

Elastic cartilage, from human auricle (Bohm and Davidoff).

is characterized by elasticity and resiliency. Its matrix
mainly consists of a network of elastic fibres the meshes of
which contain the cartilage-cells.

Cellular cartilage is a primitive form of cartilage, and con-
sists of cartilage-cells cemented together in a dense cellular
mass with scarcely any intercellular matrix. It occurs in
man only at an embryonic period, making up the primitive
vertebras; it is found in the ear of mice and some other animals.

THE TISSUES.

Bone (Fig. 25) is another specialized form of connective
tissue, made up of bone-cells or corpuscles and an intercellular
matrix impregnated with calcareous salts. It occurs in two
forms, compact, making up the greater part of long bones and
the outer part of all bones, dense and solid ; and cancellous, in
the ends and lining the medullary canal of long bones and in
the interior of all other bones ; it is loose and spongy, consisting
of spaces (cancelli) separated by thin osseous walls.

The material of which bone is composed is divisible into
two kinds, organic and mineral. By burning, the organic
portion is destroyed, leaving the mineral portion ; while on

FIG. 25.

Cross-section of compact bone, showing Hayersian systems, bony lamellae,
lacunae, and canaliculi (Klein).

treatment with acid the mineral matter is removed, or the
bone is " decalcified," the organic material remaining as a
tough flexible substance.

The bone-cells are modified connective-tissue cells, of a
flattened shape, with numerous fine processes projecting from
them in all directions. The bodies of the cells occupy the
spaces called the lacunce, while the processes occupy the
canaliculi. •

The matrix consists of dense fibrous organic matter (such as
appears in decalcified bone) impregnated with calcareous salts.
It is arranged in series of concentric lamella1, which form four

BOXE-MARRO W. 57

kinds of systems — Haversian, peripheral, peri-medullary, and
intermediate.

A Havcr*ian system consists of a series of concentric
lamellae surrounding a Haversian canal, a small round canal
containing blood- and lymphatic-vessels and marrow, running
generally lengthwise the bone, and communicating and con-
tinuous with the interior marrow- cavity. Between the
adjacent lamellae at short intervals are spaces called lacunae,
occupied by the bone-cells; connecting the lacunae are numer-
ous minute passages called canaliculi, occupied by the processes
of the cells. The canaliculi afford communication for the
passage of nutrient fluids from the Haversian canals through-
out the adjacent lamellae.

The peripheral or circumferential lamella? are a series of
subperiosteal lamellae, similar to the Haversian lamellae,
surrounding the entire bone. In places there are fibres
piercing the peripheral lamellae at right angles — perforating
fibres, or fibres of Sharpey.

The peri-medullary lamella? are a similar series surrounding
the marrow-cavity.

The intermediate or interstitial lamella? are scattered irreg-
ularly about in the bone substance, and are the remains of old
systems that in the course of the growth of the bone have
been partially removed.

The periosteum, the covering membrane of bone, is com-
posed of two layers: an outer firm fibrous protective layer;
and an inner loose layer well supplied with blood and connec-
tive-tissue cells (or osteoblasts), which has important functions
in the growth of bone and is hence called the osteogenetic
layer.

Bone-marrow : The cavities in bone — the cancelli of spongy
bone, the medullary or marrow-cavities of long bones, and
the Haversian canals — contain a soft vascular tissue, the
ni<trroir. which is of two kinds, red and yellow.

Red marrow occurs in cancellous bone in the adult, in all
bone in the young. It consists of delicate connective tissue,
a rich vascular network including large venous sinuses,
quantities of cells called marrow-cells, and fat-cells. The
marrow-cells are of several kinds, chief among which are : («)
plastic rounded connective-tissue cells, many of \vhich in

58 THE TISSUES.

growing bone become osteoblasts and aid in bone-formation ;
(b) large multinucleated giant cells, or inyeloplaxes, which are
probably osteoclasts and effect bone- absorption ; (c) crytkro-
blasts, free nucleated cells, colored by and containing haemo-
globin, probably connected with the development of red blood-
corpuscles ; and (d) cells containing oxyphile granules, re-
sembling the eosinophile leukocytes of normal blood;
other cells resembling the myelocytes which appear in the
blood in certain abnormal conditions ; and other forms of leuk-
ocytes.

Yellow marrow occurs in the medullary cavities of long
bones and larger cancelli of the adult. It is similar to red
marrow, except that it contains large quantities of fat-cells, or
marrow-cells distended with fat, to which it owes its oiliness
and straw color.

The function of marrow is partly to form bone-substance,
partly to form red blood-corpuscles. Genetically the marrow
is a continuation or offshoot of the osteogenetic periosteal
layer.

The development of bone takes place by two methods, carti-
laginous and membranous.

Cartilaginous bone-formation (Fig. 26) : Most of the bones,
especially the long bones, are in the embryo first formed of
hyaline cartilage. The conversion of this cartilage into bone
constitutes the cartilaginous method of bone-formation. In
these embryonic cartilages bone-formation begins at definite
points, the " centres of ossification." The cartilage-cells
enlarge and proliferate abundantly, and arrange themselves in
longitudinal rows, with septa between the rows composed of
the hyaline matrix. The longitudinal spaces inclosed by these
septa and filled with cartilage-cells are called the primary
areolce. These septa soon become calcified by the deposition
in them of lime salts. From the osteogenetic layer of the
periosteum loops of bloodvessels then grow into the cartilage,
accompanied by connective-tissue cells, and by large multi-
nucleated cells called osteoclasts, which have the power of
absorbing the cartilage and bone-substance and thus open
passages and spaces. The cartilage-cells filling the primary
areolse disappear, and communications are made between the
areolse by perforations through their calcified walls, though

MEMBRANOUS BONE-FOEMATIOy.

FIG. 26.

these walls are only partially absorbed. The larger spaces
thus formed are termed secondary areolce. Connective-tissue
cells now deposit themselves on the calcified walls of the
secondary areolse and become osteoblasts, or bone-formers.
They secrete a layer of bony -
substance, in which they and
their processes become buried ;
they thus become bone-cells,
in lacuna?, with their proc-
esses in canal iculi. When
one layer of bone is thus de-
posited, other osteoblasts be-
come fixed on the new sur-
face and form another layer.
This process proceeds from
the periphery of the spaces
inward, until only a small
passage is left, the Haversian
canal, the surrounding lamellae
constituting a Haversian sys-
tem. The formation of bone
proceeds in this manner away
from the centres of ossification;
hence there are layers of grow-
ing cartilage intervening be-
tween the different ossifying
areas, as between the shaft
and the epiphyses of long
bones. .Not until the ^ bone Development of bone cartilaginous

attains its lull growth are method ( Klein).

these intervening cartilagi-
nous portions fully converted into bone. The bone formed
by the cartilaginous method is temporary, being subsequently
removed and renewed by the membranous method ; while
the interior of long bones becomes excavated to form the
marrow cavities.

Membranous bone-formation : Some of the bones, as the flat
bones of the skull, are preceded in the embryo by white
fibrous membranes. The conversion of these into bony tissue
(intramembranous bone-formation) and the formation of bone

60 THE TISSUES.

by the osteogenetic layer of the periosteum (subperiosteal bone--
formation), which are substantially identical processes, con-
stitute the membranous method of bone-formation. All per-
manent bone is formed in this way. The process begins with
a deposition of osseous matter upon some of the fibres, a por-
tion of the connective-tissue cells assuming the function of
Gsteoblasts. A bony reticulum is thus formed, in the meshes
of which bone-formation is continued by the osteoblasts.
Along with the formation of bone, absorption, replacement,
and remodelling of the bone constantly go on. Osteoclasts
excavate spaces in the bone previously laid down, in which
new Haversian systems are formed. The remains of old
Haversian and peripheric lamella thus partially destroyed
constitute the interstitial lamellae. The spaces occupied by
osteoclasts are called Howship's lacunce. In the bones which
develop from membrane a membranous portion persists and
continues to grow between the ossifying areas or at the
margins, until the bones attain their full growth, when they
are completely ossified.

Muscle.

The muscle-cells are specialized cells having the property of
contractility highly developed. Their function is motor, to
effect the motions of the body. Muscle is derived from the
mesoblast. Muscular tissue is mainly made up of the cellular
elements, the intercellular substance being scanty and incon-
siderable. There are three varieties of muscle-cells :

Striated, or voluntary ;

Cardiac ;

Involuntary, or non-striated.

Striated or striped muscle (Figs. 27, 28) makes up all the
voluntary muscles of the body. The cells are very much
elongated protoplasmic fibers, generally 10 to 50 micromilli-
metres in diameter, and 20 to 40 millimetres long, or even
longer. In shape the cells or fibres are cylindrical or pris-
moidal, slightly fusiform, with tapering or blunt rounded
extremities ; in cross-section they are usually rather polygonal.
Each cell is inclosed in a delicate homogeneous separable
envelope, the sarcolemma. The fibres are usually straight and

STRIATED OR STRIPED MUSCLE. 61

unbranched,but in occasional situations they branch and anasto-
mose. Each cell has many oval nuclei, arranged with their long
axis longitudinal to the cell, situated in mammals just under-
neath the sarcolemma. The body .of
the cell under moderate magnification FIG. 27.

exhibits characteristic transverse striae
or stripes, consisting of delicate alter-
nately dark and light lines.

The fibres are arranged parallel to
one another, with overlapping ends. Portiou oi str
They are grouped in bundles or fas-
ciculi, all of which bound together in fibrous sustentacular
tissue make up an entire muscle. The connective tissue
surrounding and enclosing the entire muscle is called the epi-
mysium; that enveloping the separate fasciculi is called the
perimysium ; while the delicate and scanty connective tissue
within the fasciculi among the individual muscle-cells is the
endomysium.

The sarcolemma of each fibre is connected with the endo-
mysial tissue, and through this with the tendon. Thus each
cell when it contracts exerts more or less direct traction on
the tendon. The muscle-fibres are richly supplied with blood
by a capillary network in the endomysium. On the surface
of each fibre is a flattened nerve-terminal.

The minute structure of striated muscle is very difficult to
make out and has not been satisfactorily determined, and
authorities are not agreed in their interpretations of the ap-
pearances presented.

The appearance of cross-striation is produced by alternating
dark and light discs or segments in the substance of the
muscle-cells. By treatment with weak acids these segments
can be separated from one another in the form of transverse
discs. The individual fibres also exhibit a longitudinal striation
as well as transverse, and by treatment with alcohol and teas-
ing can be broken up into fine longitudinal fibrillce ; these
fibrillse are arranged in bundles, called fields of Cohnheim.
The protoplasm of the muscle-cell is made up of two parts,
a dark sarcous substance (" anisotropic," or doubly refracting)
and a colorless, hyaline, probably semifluid substance (" iso-
tropic," or singly refracting), sometimes called sarcoplasm.

THE TISSUES.

FIG. 28.

These two substances make up the dark and light portions,
respectively, of voluntary muscle. On close examination the
light or clear transverse segments are found to be divided
into two discs by a delicate transverse line, by some consid-
ered to be a definite membrane and called the membrane of
Krause, and by others regarded as a row of minute granules,
called Dobie?s granules.

The transverse discs separated by the " membrane of
Krause" are called sarcous discs or compartments; each is

composed of a dark segment with
half of the adjacent light segment
on each side. The dark portion of
each sarcous disc, again, is not
homogeneous, but is made up of
minute dark longitudinal rods, or
sarcous elements, separated by the
light substance, or sarcoplasm. The
sarcous elements of adjacent discs
correspond to one another and with
the intervening granules of Dobie,
so as to form the continuous lon-
gitudinal fibrillse. The appear-
ances above described are those
of relaxed or extended muscle.

When the muscle contracts the fibres become shorter and
thicker; the sarcous elements seem to divide in their middle,
forming a clear transverse line or segment, called the line of
Hensen ; while the ends of the elements approach the ends of
the corresponding elements of the adjacent discs, and tend to
obliterate the clear segment between. Thus, in contracted
muscle the light and the dark stria3 seem to occupy positions
precisely reverse to those of relaxed muscle. The mechanism
of muscular contraction is not, however, well made out.

Cardiac muscle : The muscular substance of the heart has
an individual character of its own (Fig. 29). The individual
cells, much shorter than those of the striated variety, are
cylindrical in shape with square or serrated ends; they send
off branches which unite with neighboring cells. Adjoining
cells meet end to end, the. ends being so closely cemented
together that the points of junction cannot be detected with-

Striated muscle-cells in
section (Klein).

INVOLUNTARY OR NON-STRIATED MUSCLE. 63

FIG. 30.

out special preparation of the specimen. Laterally the cells
are not closely crowded, but are separated
by slight intervals filled with delicate con-
nective tissue and vascular channels. The
cells have no separable sarcolemma. Each
cell has a single nucleus, situated in the
centre of its protoplasm. The cells are
somewhat striated both longitudinally and
transversely.

Involuntary or non- striated muscle (Fig. 30)
is widely distributed throughout the viscera,
being found in especial abundance in the
alimentary canal, bloodvessels, bladder, and
uterus. Its movements are not under the
control of the will, but are of an automatic
nature and are more slow and continuous
than those of the voluntary muscles.

Involuntary, non-striped, or smooth mus-

Fio. 29.

Cardiac muscle (Dunham), a. nucleus ;
6, c, cytoplasm ; d, cement at junction
of cells; e, areolar or "interstitial"
tissue between the cells ; /, capillary.

Involuntary muscle-
cell (Schafer.) The
nucleus is not repre-
sented sufficiently
long.

cle-cells are slender and fusiform in shape, each with a single

64 THE TISSUES.

characteristic elongated or rod shaped nucleus in its centre.
The cells have a parallel and overlapping arrangement, held
together by a scanty cement-substance, and form sheets, rings,
or tubes of muscle. Indistinct longitudinal and transverse
markings are sometimes observed, the latter being probably
folds in the cell-walls. The cells have an envelope but no
separable sarcolemma. Some authorities describe involuntary
muscle-cells as having longitudinal ridges, or " intercellular
bridges," on their surface, which unite with the ridges of the
adjacent cells.

Nerve -tissue.

The elements of the nervous structures are greatly extended
cells, called neurons, which for practical convenience may be
divided into nerve-cells, nerve-fibres, and nerve-terminals.
Their description will be deferred to that of the nervous
system in general.

Free Cells and Body-fluids.

The tissues considered hitherto are all fixed. The present
class is a somewhat miscellaneous assemblage of those body-
elements that are not fixed, but free or fluid.

They may be grouped as follows : 1 . Unattached cells, free
in the solid tissues. 2. Cellular fluids — that is, fluids in
which free living cells are suspended, as the blood. 3. Simple
homogeneous fluids, mainly secretions. 4. Emulsions.

The free cells, situated for the most part in the solid tissues,
but not attached to them, are represented mainly by the
wandering cells, the lymphoid cells of lymphoid tissue, and
ova. The so-called wandering cells are leukocytes or lymph-
corpuscles which have escaped from the bloodvessels or
lymphatic structures and exist free and migratory, especially
among the meshes of the opener or areolar forms of connec-
tive tissue. The small spherical lymphoid cells, with large
prominent nuclei, which occur crowded in the meshes of
retiform or lymphoid tissue, are very similar to and closely
related to the corpuscles of lymph. Some of the cellular
elements of bone-marrow might also perhaps be included in
this group. The ova of the lower animals are free cells ; and

SIMPLE OR HOMOGENOUS FLUIDS. 65

in mammals they are free from their departure from the ovary
until their attachment to the uterus, and even afterward they
are in a sense independent.

The cellular fluids of the body are the blood, lymph, and
semen. They consist of actively vital cells free in a fluid
matrix. They can be regarded as liquid tissues analogous in
all respects to the solid tissues, being composed of cells and
an abundant intercellular substance, which in this case is fluid.
The latter differs from the matrix of the solid tissues, how-
ever, in that it is not produced by the vital activities of the
cells suspended in it.

The blood consists of cells or corpuscles of three kinds, red
corpuscles, white corpuscles or leukocytes (of which there are
several varieties), and blood-plates.

Lymph consists of a fluid portion, or serum, containing
lymph-corpuscles, which are similar to or identical with some
forms of leukocytes. Leukocytes and lymph-corpuscles often
find their way into the fixed tissues or on mucous surfaces.

Semen is a thick opaque fluid containing large numbers of
spermatozoa, together with some loosened cells and granules.

The simple or homogeneous fluids are mainly the secretions of
the various glands, consisting usually of clear, transparent solu-
tions without any proper cellular or formed elements. Under
the microscope they exhibit no structural features, and the
study of their composition is a matter for chemical or micro-
chemical methods. Among them may be mentioned the urine,
perspiration, saliva, bile, gastric juice, etc. ; also the fluids
moistening the mucous surfaces, of which mucus is a promi-
nent constituent.

Although these fluids contain no cellular elements as proper
or essential ingredients, yet they sometimes, notably the saliva
and urine, contain a few adventitious cells derived from the
mucous membrane lining the surface of the cavities where
they occur. The chief cells thus found are leukocytes or
lymph-cells (as the "salivary corpuscles") which have worked
their way through the mucous membrane to the surface ; also
ordinary epithelium-cells cast off from the epithelial covering ;
and "mucous corpuscles," or " mueocytes," young germinal
epithelium-cells from the lower epithelial layers (especially in
the bladder) which have grown rapidly and been thrown off

5— Hist.

66 THE TISSUES.

prematurely as free spherical corpuscles, usually larger than
leukocytes.

Emulsions : Milk and chyle are emulsions, as are also the
yolk of birds' eggs and the milky juice of certain plants. By
means of certain substances, as albumin, oil may be caused to
form a permanent mixture, or emulsion, with water. The oil
forms minute spherules or granules enveloped in a viscid sub-
stance, which causes them to retain their shape, and suspended
in the watery vehicle. Milk and chyle contain large numbers
of such fat-granules, which are very minute and are sus-
pended in an abundant aqueous fluid. Their opacity and
whiteness are due to the reflection of the rays of light from
the granules. In artificial emulsions the spherules of fat are
much coarser and the proportion of water that can be intro-
duced far less than is the case with these natural emulsions.

CHAPTER V.
GLANDS; MUCOUS AND SEROUS MEMBRANES; ORGANS.

BEFORE beginning the consideration of the organs and sys-
tems in detail, it will be convenient to consider briefly : (1)
certain composite structures of wide distribution, namely,
glands, mucous membranes, and serous membranes ; and (2)
organs in general.

Glands are of two entirely distinct types : (a) lymphoid and
blood-glands ; and (6) secretory or epithelial glands.

The lymphoid glands, as the lymphatic glands, thymus,
tonsils, and lymphoid tissue generally, consist of an open net-
work of retiform tissue the meshes of which are filled with
lymph-corpuscles and lymph. The lymph-stream passes
directly through them. They have no proper secretion,
possess no outlet-ducts, and communicate only with lymphatic
vessels. Their function is not completely understood, but
they partly serve to develop some of the corpuscular elements
of the blood and lymph, and partly to arrest noxious sub-
stances in the circulation.

The blood-glands, as the spleen, bear the same relation to the
blood-stream that the lymphoid glands do to the lymph-
stream. In general structure they resemble the lymphoid
glands.

The secretory glands remove or secrete from the blood
various substances and fluids needed for special purposes.
The active agent in this process is the glandular epithelium,
which forms a layer supported on a basement-membrane ;
beneath and in close relation with the epithelium is a rich
capillary blood-supply ; on the free surface of the epithelium
is an open space or cavity in which the secreted product col-
lects and is carried away. Such is the general structure of
all secretory glands : a sac of epithelium with blood-supply
on the outside and a collecting cavity inside. The epithelium

68 GLANDS; MUCOUS AND SEROUS MEMBRANES.

of the secreting portion of glands is usually different from
that of the ducts.

Secretory glands are of two kinds : closed or ductless glands ;
and the ordinary open glands with ducts.

The secretory ductless glands are the thyroid, parathyroids,
adrenals, pituitary body, and pineal body. They have no
outlets nor ducts, and hence their secretions are not discharged
elsewhere except by reabsorption into the blood or lymph cir-
culation. The lymphoid and blood-glands are also " duct-
less."

The open glands are the ordinary variety, as the kidney,
salivary glands, pancreas, with outlet-ducts through which
their secretions are discharged.

In addition to these secreting bodies, certain endothelial
structures may be mentioned, as bursse, synovial sacs, etc.,
which contain glairy lubricating fluids produced by the
endothelium also by a true secretory process.

Internal and external secretions : The purpose and mechan-
ism of the ductless glands, closed as they are, have long been
obscure, but recent theories afford some explanation of the
subject. According to these theories, the secretions elaborated
by glands are of two kinds, internal and external.

The external secretions are those of the ordinary kind, dis-
charged through the ducts of the glands and conveyed to the
places where their functions are carried out, as the tears, the
bile ; their action is easily comprehensible.

The internal secretion, however, is not discharged by gland-
ducts, but is absorbed into the circulation and there serves
purposes useful in the animal economy. This is the only
kind of secretory activity which the ductless glands manifest.
The secretion of the thyroid, for instance, when in the blood,
increases oxidation, promoting metabolism, and increasing the
rapidity of cell-life ; stimulates cerebral activity, makes the
heart action more rapid, causes palpitation, and dilates the
bloodvessels. That of the suprarenals is a powerful vaso-
motor constrictor and probably serves to maintain vascular
tone.

The effects of these internal secretions are most markedly
manifested when they are absent from the blood, as when the
glands producing them are removed or impaired by disease ;

INTERNAL AND EXTERNAL SECRETIONS.

thus, removal or impairment of the thyroid causes myxoedema ;
of the suprarenals, Addison's disease ; of the pituitary body,
acromegaly. It would seem as if the presence of the internal
secretions in the blood afforded stimuli necessary to preserve

FIG. 31.

FIG. 32.

Simple tubular gland.
FIG. 33.

Compound tubular gland.
FIG. 34.

saccular gland.
Morphologic types of secretory glands (Dunham).

Compound or racemose saccular
gland.

a certain tonus and produce definite reactions of the bodily
cells.

Some of the glands with ducts, moreover, seem to produce

70 GLANDS,- MUCOUS AND SEROUS MEMBRANES.

internal as well as external secretions. Thus, the glycogenic
and urea-forming functions of the liver and the relation of the
pancreas to glycosuria are instances of internal secretory action.
Morphology of secretory glands (Figs. 31-34) : The secret-
ing glands, according to their form, are divisible into two
classes: tubular and saccular ; each of these, again, may be
simple or compound.

Simple tubular glands consist of single tubes lined with
epithelium, with one end closed and blind and the other
opening on the skin or mucous surface. The glands of
Lieberkiihn and some of the gastric and uterine glands are
typical examples ; the sweat-glands are single tubes, modified
in having the secreting portion much coiled.

In compound tubular glands the tubular structure is still
present, but the tubes branch and divide, discharging into a
common duct. Some of the gastric and uterine glands
exhibit the simplest gradations into this type. The kidneys,
testicles, and liver are compound tubular glands.

Simple saccular glands consist of a single rounded or
spherical cavity or glandular sac with a small outlet to the
surface. Some of the simplest sebaceous glands may be of
this type, but they scarcely occur otherwise in mammals.

Compound saccular or racemose glands, as the salivary,
mucous, lachrymal, sebaceous, and mammary glands, consist
of numbers of saccules opening into common ducts, and these
again uniting in larger ducts, much like a bunch of grapes.
In compound glands the ultimate saccules or alveoli which
communicate with common ducts form well-marked groups,
so that a division of the gland into lobes and lobules is easily
recognizable. The lobular divisions of glands are usually
separated by distinct partitions of connective tissue, inter-
lobular^ septa. Well-marked divisions of the ducts are also
recognizable, corresponding to their degree of division and to
their situation and relation to the lobules. Within a lobule is
a small division of the ducts, the. intralobulur dud, into which
the ultimate alveoli of that lobule all empty. The short duct
by which each individual saccule or alveolus empties into the
intralobular duct is called an intermediate duct; the union of
the intermediate ducts forms the intralobular ducts. The
intralobular ducts unite to form the interlobular ducts, which

MUCOUS GLANDS.

are larger and lie in the connective tissue separating the
lobules. By the union of the interlobular ducts the large
common duet or ducts of the whole gland are formed.

According to the nature of their secretion and corresponding
characteristics of the gland-cells, most secretory glands are
divisible into serous glands, mucous
FIG. 35. glands, and fatty glands.

Serous glands (Fig. 35), as the parotid
and pancreas, secrete limpid watery fluids
or solutions. The secreting-cells are
spheroidal or polyhedral, granular, dark
and opaque, stain deeply, and have rounded
nuclei nearly centrally located. The ap-

Alveolusof serous gland J

(Schieflerdecker). pearance ot the cells varies somewhat
according to the stage of secretion. When,
after resting for a time, they are charged with secretion, they
are distended, clearer, less opaque, stain less deeply, and contain
an abundance of granules. After being exhausted by pro-
longed secretion they are shrunken or diminished in size ;
darker, more opaque, and more deeply
stained (from condensation of the pro-
toplasm) ; and less granular, having
discharged their granular contents into
the lumen of the gland.

Mucous glands (Fig. 36), as the sub-
lingual, secrete a viscid, mucinous
fluid, wrhich lubricates the mucous sur-
faces. Goblet epithelium-cells secrete
a similar substance, and the character- Alveolus
istics of these cells are very similar
to those of the cells of mucous glands. Small racemose
mucous glands are widely distributed in mucous membranes,
having their alveoli in the submucosa and their ducts opening
on the surface. The secreting-cells of mucous glands, when
in the resting stage and distended with their mucinous secre-
tion, are large and swollen, unstained, clear, and transparent,
especially in the superficial portion ; their nuclei and body-
protoplasm are crowded well toward the bases of the cells.
When exhausted by continued activity they are smaller, less
clear, and more granular in appearance.

FIG. 36.

0m KP°US gland'

72 GLANDS; MUCOUS AND SEROUS MEMBRANES.

Fatty glands : The sebaceous and mammary glands produce
the fatty constituents of their secretions by a fatty degenera-
tion or infiltration of the protoplasm of the gland-cells. The
cell-bodies become swollen and infiltrated with globules of
fat, which are later discharged into the lumen.

Mucous membranes : The mucous membranes are those
lining the spaces within the body that communicate directly or
indirectly with the exterior. There are three distinct continu-
ous tracts of mucous membrane : the respiratory-alimentary,
the genito-urinary, and the mammary. At the orifices and
along portions of these tracts the mucous membrane is a con-
tinuation of and similar in structure to the skin. In some situ-
ations the function of mucous membrane, like that of the skin, is
chiefly protective, and in these places it most resembles the
skin. In other situations mucous membrane has special
functions, and its structure varies accordingly.

Mucous membrane is usually described as being, in general,
composed of two layers, the mucosa and the submucosa,
which are commonly situated on a muscular or fibrous bed.

The mucosa consists of : (a) a superficial layer of epithelium,
stratified squamous, columnar, or ciliated, corresponding to
the epidermis of the skin. Beneath the epithelium is (6) the
tunica propria, a layer of connective tissue, white-fibrous or
elastic, corresponding in general to the corium of the skin, but
varying greatly in different situations. Its upper or outer
surface is condensed to form a basement-membrane for the
support of the overlying epithelium. Beneath the tunica
propria in many places is (c) the muscularis mucosce, a thin
sheet of involuntary muscle-cells, some longitudinally arranged,
some transverse ; it separates the mucosa from the submucosa,
and has no analogue in the skin.

The submucosa is a layer of areolar tissue underneath the
mucosa, corresponding to the areolar subcutaneous tissue ; it
contains the larger vascular, lymphatic, and nerve branches,
which send smaller twigs and capillaries into the tunica
propria. The looseness of the subrtiucosa permits some play
or movement of the mucous layer on the layers beneath.
Lymphoid tissue, diffuse or circumscribed, is present in many
situations in the submucosa or tunica propria.

SEROUS MEMBRANES. 73

Secretion : Mucous membranes are bathed and lubricated
in a mucinous fluid, secreted mostly by goblet-cells or special
small mucous glands. Most mucous membranes lined with
stratified squamous or stratified ciliated epithelium are pro-
vided with large numbers of mucous glands ; in the stomach
and intestines (lined by simple columnar epithelium) mucus
is secreted by large numbers of goblet-cells, no mucous glands
being present. Some mucous membranes lined with stratified
squamous epithelium, however, lack both goblet-cells and
mucous glands, as in the vagina and bladder, whose mucous
secretion is ^produced by the. mucinogenous action of the
squamous cells themselves. The mucous glands when present
have their alveoli in the submucosa and their ducts penetrate
the mucosa to empty on the surface ; the cells of the secreting
portions of these glands are of the mucous glandular type,
while the ducts are lined with a different form of cell, usually
cuboidal or columnar cells similar to or merging into those of
the epithelial surface.

These are the general features of the structure of mucous
membranes, but the details vary greatly in different situations.

Serous membranes, as the pleura, pericardium, peritoneum,
tunica vaginalis, and the allied synovial membranes, line
certain closed cavities or sacs. The portion of serous mem-
branes covering the viscera is called the visceral portion, that
reflected over the outer walls of the cavity being the parietal
portion. Serous membranes consist of an interlacing fibrous
connective-tissue membrane or basis, lined on the free surface
by endothelium, while beneath is a variable amount of areolar
and often adipose tissue, the subserous tissue, connected with
the subjacent structures and analogous to the submucosa.
They contain blood and lymphatic vessels. Between the
endothelium-cells in some localities are occasional minute
orifices or lymph-stomata, guarded by small spheroidal cells ;
these open into lymphatic vessels within the membrane. Thus
the serous sacs form large lymph-spaces, communicatingdirectly
with the lymphatic channels. The function of serous mem-
branes is partly associated with that of the lymphatic system,
and is largely to obviate friction and to permit and facilitate
the gliding movement of viscera upon opposing surfaces.

74 GLANDS; MUCOUS AND SEROUS MEMBRANES.

Organs are aggregations of the elementary cells and tissues
in varying proportions and varying modes of arrangement.
The tissues of many organs can be conveniently divided into
parenchymatous tissue and sustentacular tissue.

The parenchyma of organs consists of the cells or portions
that are the active and essential agents in carrying on the
functions of the organ, such as the glandular epithelium of
glands, the air-vesicles of the lungs, etc. The sustentacular
tissue (often called interstitial tissue) of organs consists of
their connective-tissue framework, permeating and supporting
all their parts. It is usually a fibro-elastic or condensed
areolar tissue. Different parts or divisions of the sustentacu-
lar tissue can often be distinguished, such as the membranous
envelopes or capsules surrounding organs; trabeculie or septa
(interlobular tissue) traversing the interior of organs and
dividing them into lobes and lobules ; tracts of fibrous tissue
(perivascular tissue, etc.) surrounding and supporting the
vascular and nerve branches, and ducts, in their ramifications
through the organ ; and a delicate all-pervading network of
fibrous tissue (intralobular tissue) embracing and sustaining
the minutest subdivisions of the visceral and parenchymatous
substance. In addition to their sustentacular and parenchy-
matous elements organs possess as a matter of course a blood,
lymphatic, and nerve supply.

CHAPTER YL
THE CIRCULATORY SYSTEM.

THE apparatus by which the circulation of the blood
throughout the body for the nourishment of the tissues is
accomplished consists of the heart, covered by the pericar-
dium ; and the bloodvessels : arteries, veins, and capillaries.

The heart is a hollow muscular organ, whose walls are made
up of a thick mass of muscle, the myocardium, lined on the
inside by a delicate endothelial membrane, the endocardium ;
and on the outside by a serous membrane, the visceral portion
of the pericardium.

The endocardium, which lines the interior of the heart, is
similar to the lining of the bloodvessels, of which it is a
continuation. It is thinner than the pericardium. Its free
surface is lined by polygonal endothelium-cells, which lie on
a firm connective-tissue basis of interlacing white and elastic
fibres. The lowermost tissue of the endocardium merges
gradually into the delicate connective tissue which occupies
the interstices between the muscle-cells of the myocardium.

The valves of the heart and arterial orifices consist of folds
or reduplications of the endocardium, fortified and strength-
ened by additional white and elastic fibrous tissue. The tis-
sues at the bases of the valves are strengthened into well-
marked fibrous rings, which serve as a basis for the attach-
ment or insertion of the valves and muscular bundles of the
myocardium.

The myocardium is a muscular mass making up the main
substance of the heart. The cardiac muscle-cells of which it
is composed are of a kind peculiar to the heart, and have been
already described (Fig. 29). The muscular fibres are arranged
in bundles or layers which in different places run in different
directions, transverse, longitudinal, oblique, spiral, in an intri-
cate manner.

THE CIRCULATORY SYSTEM.

Cardiac muscle-tissue is not compact, but the sides of the
muscle-cells are separated by slight intervals or interstices
through which delicate connective tissue (the interstitial tissue),
capillaries, lymphatics, and nerves permeate the entire myo-
cardium. The blood-supply of the heart, including the endo-
cardium and visceral pericardium, is derived from the coronary
vessels; the muscle-cells are richly supplied with capillaries.

The pericardium is a typical serous sac, consisting of a fibro-
elastic membrane (fibrous pericardium) lined on the free interior
surface by a single layer of polygonal endotheli urn-cells (serous

FIG. 37.

Cross-section of artery (Dunham), a, endothelial lining ; 6, internal elastic lamina ;
c, tunica media ; d, tunica adventitia ; e, adipose tissue ; /, small nerve.

pericardium) ; beneath which is the subserous or subpericardial
areolar tissue, which in this situation often includes masses of
fatty tissue. The visceral portion of the serous pericardium,
sometimes called the epicardium, envelops the outside of
the heart, while its parietal portion is reflected on and lines
the inner surface of the fibrous pericardium. Under the portion
of the pericardium which covers the heart the subpericardial
tissue, areolar and fatty, is continuous with and merges into
the interstitial connective tissue of the myocardium.

ARTERIES. 77

Arteries : The arteries vary in structure somewhat — that is,
in the relative proportions of their several constituents — ac-
cording to their size and degree of subdivision (Fig. 37). The
coats of arteries are usually described as consisting of three
divisions, the tunica intima, tunica media, and tunica adven-
titia. The structure of medium-sized arteries, or all but the
largest and the smallest, is as follows :

The tunica intima, or internal coat, consists of three layers.
It is lined internally by endothelium, a single layer of flat
sqtiamous cells uniting by somewhat sinuous edges, oval and
elongated in shape and with oval nuclei ; the cells and nuclei
lie with their long axes parallel with the course of the
artery. These cells present a smooth surface to the blood-
stream.

Beneath the endothelium is the subendothelial connective
tissue, a thin delicate layer of white and elastic fibrous tissue
with stellate connective-tissue cells. In the smallest arteries
this layer becomes thinner and finally disappears.

The lowest layer of the tunica intima, separating it from
the tunica media, is the internal elastic lamina, a thin but
prominent layer of interlacing yellow elastic fibres forming a
perforated or sometimes almost continuous membrane ; it is
sometimes called the afenestrated membrane of Henle." In
empty and contracted arteries this elastic lamina is thrown
into longitudinal folds, and in cross-sections of arteries it con-
sequently presents a very conspicuous and characteristic ap-
pearance as a clear sinuous yellow line surrounding the lumen
of the vessel.

The tunica media is a thick middle coat, between the intima
and adventitia, consisting chiefly of intermingled yellow elastic
fibres and involuntary-muscle cells, along with a small amount
of white fibres. The muscle-cells are for the most part ar-
ranged circularly or transversely, but in a few arteries longi-
tudinal cells also occur sparingly. The elastic tissue occurs
as sinuous fibres, networks, and plates. In relative quantity
the elastic and muscular elements vary inversely to each other
according to the size of the artery.

* In the large arteries the elastic tissue greatly predominates
in amount over the muscle ; as the arteries decrease in size
these proportions are gradually reversed, until in the small

78 THE CIRCULATORY SYSTEM.

arteries the media is mainly composed of muscle-cells, with
elastic tissue only scantily represented.

This arrangement confers great elasticity on the largest
arteries, so that they convert the spurts of blood intermittently
pumped from the heart into a more even and continuous cur-
rent ; while the smaller arteries, by the action of the vaso-con-
strictor and vaso-dilator nerves upon their muscular walls and
their calibre, are kept well under the control of the nervous
system, which in this way exercises a full and highly coordi-
nated control over the circulation and amount of blood-supply
in all parts of the body.

In some arteries an external elastic lamina, similar to but
less well marked than the internal elastic membrane, can be
distinguished, marking the outer limit of the tunica media and
separating it from the tunica adventitia.

The tunica adventitia, the outer coat of the arterial wall, is
a layer of fibrous and elastic tissue, containing perivascular
lymphatics and the vasa and nervi vasorum, or the small
bloodvessels and nerve-filaments that supply the walls of the
artery itself. The adventitia is of indefinite and variable
thickness in different situations ; the portion next to the
media is a firm, strong tissue, while the more remote portions
become looser and more areolar and merge gradually into the
neighboring connective tissues.

In the largest arteries, as the aorta and pulmonary artery,
the subendothelial tissue is thick and firm, and the internal
elastic lamina is ill defined. The tunica media is made up
mainly of elastic plates and reticula, the muscle-cells being
present in relatively small proportion.

As the arteries decrease in size, the subendothelial tissue and
the elastic elements of the media diminish and ultimately
disappear, the muscle-cells become fewer and scattered, the
adventitia decreases in amount, and the internal elastic lamina
becomes thinner and finally absent. The endothelium persists
throughout.

The smallest terminal arteries, then, are lined with endo-
thelium, resting on the thin remnants of the subendothelial
connective-tissue and elastic layers; outside of this are trans-
verse involuntary muscle-cells in a single layer or scat-
tered and separated by intervals ; and surrounding all is

VEINS. 79

scanty connective tissue representing the remains of the
adventitia.

In small arteries, viewed longitudinally (or from the side),
the transverse muscle-cells, with their conspicuous rod-shaped
nuclei, present a very characteristic appearance by which
vessels of this size are easily recognized.

When, finally, all the coats have disappeared except the
endothelium, the artery has merged into a capillary.

Veins : The structure of veins is much the same as that of
arteries ; but they have a larger calibre, thinner walls, more
white fibrous tissue, and less muscle than the corresponding
arteries, and they are provided with valves.

The walls of veins, as of arteries, consist of three coats,
the tunica intima, tunica media, and tunica adventitia.
These coats, however, are often indistinctly marked off
and merge into one another without well-marked dividing-
lines.

The tunica intima is lined internally with a single layer of
endothelium-cells, which are more polygonal and less elongated
in shape than are those of arteries. The subendothelial layer
consists of white and elastic tissue. The internal elastic
lamina in veins is often poorly defined.

The tunica media consists of white and elastic fibrous tissue
and involuntary muscle-cells, which are mostly arranged
circularly, but in some situations partly longitudinally also.
The media is much thinner and contains less muscle than in
arteries.

The tunica adventitia is a fibro-elastic outer sheath, often
thick and well marked, containing vasa vasorum and in some
situations longitudinal non-striated muscle-cells.

The valves of veins are folds of the tunica intima, strength-
ened bv additional connective tissue.

At the junction of the large rein* with the cardiac auricles
the peculiar muscle of the heart is continued for a short dis-
tance in the venous walls. The walls of the veins of the
lower extremities are thicker and more muscular than those of
the upper part of the body.

The venous N/////.NVX of the interior of the skull consist
of an endothelial layer resting on fibrous tissue, and occupy

80 THE CIRCULATORY SYSTEM.

spaces formed by separation of the layers of the dura
mater.

Some veins are devoid of muscle-tissue.

Capillaries : The capillaries are minute tubes formed of a
single layer of elongated flat squamous nucleated endothelium-
cells, with their long axes arranged longitudinal to the course
of the vessels. They are, therefore, continuations of the
endothelial linings of the arteries and veins, but divested of
all other coverings, except that whatever traces of connective
tissue may surround the endothelial tubes may be regarded as
vestiges of the adventitia.

At the junction of the endothelial cells in places are small
points, which are perhaps stomata or openings, by which the
escape or migration of leukocytes through the wall of the capil-
lary is effected or facilitated.

The capillaries form a system of exceedingly numerous short
minute passages connecting the terminal arteries on the one
side with the initial veins on the other. They branch and
anastomose so as to form reticula or networks, varying in the
closeness, form, and arrangement of the meshes in different
organs and situations, according to the blood supply locally
required. The capillaries lie in intimate relation with all the
tissues, and nearly all parts of the body are closely permeated
by these channels. From the capillaries the blood accom-
plishes its metabolic and nutritional action on the body-tissues.
The capillaries are therefore the ultimate active functional
elements of the circulatory system, to which all the rest of
the circulatory apparatus serves a subordinate and tributary
purpose.

The thin walls of the capillaries are highly endowed with
the vital properties of protoplasm, and are well fitted for the
exosmosis of nutrient fluids ; the endosmosis of carbon dioxide
and other waste products of tissue-katabolism ; and the passage
of leukocytes through them.

Vascular sinuses : In some situations the vascular passages
are dilated or distended in the form of cavernous spaces or
sinuses (often called venous sinuses), lined with endothelium
and communicating with arteries and veins, and with one

VASCULAR SINUSES. 81

another. Such sinuses may be interposed between the terminal
arteries and the commencing veins, taking the place of capil-
laries, as in the spleen and bone-marrow.

The erectile tissue of the male and female genitals consists
of similar vascular sinuses so arranged that when the exit of
the blood is checked by muscular compression of the outlet-
veins the spaces are distended with blood and the organ be-
comes turgid and erect.

6- Hist.

CHAPTER VII.
THE LYMPHATIC SYSTEM.

Tx the main the lymphatic system consists of a series of ves-
sels or channels distributed throughout the entire organism and
serving chiefly for draining away superfluous fluids in the
tissues and returning them into the blood.

The fluid contained in these channels is the lymph.

The absorptive action of the lymphatics, as in the intestinal
walls and the removal of substances introduced hypodermi-
cally, is allied to their drainage function. In some situations,
as in the cornea and bone, lymph-channels afford the only
passages by which fluids can permeate the tissues for the
purpose of nourishing them.

In the course of lymphatic vessels are also interposed gland-
ular structures, which among other functions have the power
of arresting noxious and toxic bodies in the lymphatic circu-
lation.

The morphologic elements of the lymphatic system may be
stated to be lymph-spaces and origins, lymphatic vessels,
lymphoid tissue, and lymphatic glands.

Lymph-spaces : The interstices or empty spaces in tissues,
especially connective tissues, form cavities which may contain
lymph and communicate directly or indirectly with lymphatic
vessels. Cell-spaces, the intervals between (connective-tissue)
cells and their processes and the walls of the cavities or
lacunae in which they are situated (as in bone and the cornea),
often afford sufficient room for the passage of lymph. In
some instances separations or fissures in tissues form lymph-
spaces, without any specialization of the walls; in other cases
the walls of the spaces are lined partially or whollv with
flattened connective-tissue cells or endothelium. The lacunae
and canal iculi of bone, the cell-spaces and channels in the
cornea, the minute intervals between the prickle-cells of the
epidermis, form communicating passages by which lymph can

ORIGINS OF THE LYMPHATIC VESSELS. 83

percolate through these tissues, which are not supplied by
blood-capillaries, and afford pabulum for their nutrition which
would otherwise be unprovided.

Cell-spaces are also especially observable in the fibrous
tissue of the central tendon of the diaphragm, irregular stellate
lymph-spaces corresponding to connective-tissue cells, with
branches communicating with one another and perhaps with
lymph-vessels.

The spaces in areolar tisane also serve as lymph-spaces,
communicating freely with the lymph-vessels, and from their
looseness are capable of holding large accumulations of lymph
and fluid, as in oedematous conditions and subcutaneous injec-
tions. These spaces are simply fissures in the substance of
the connective tissue, without any specialized walls.

In certain regions, notably the nervous centres, occur well-
marked perivascular and perineurial lymphatics, consisting of
longitudinal passages or clefts in the tunica adventitia of the
bloodvessels and fibrous tissue surrounding the nerves ; these
passages when well developed may be lined with endo-
thelium.

The open meshes of lymphoid tissue also constitute lymph-
spaces, partially lined with flat connective-tissue or endo-
thelioid cells.

The serous sacs, as the pleura, pericardium, peritoneum,
sy no vial sacs, bursse, etc., may be regarded as representing
highly developed lymph-spaces. They are large cavities
completely and definitely lined by serous membranes, which
have been already described as fibrous membranes lined on
the free surface by endothelium. The cavity of the serous
sacs communicates with the lymph- vessels by stomata. The
function of serous membranes is, however, apparently more
to obviate friction and facilitate motion between opposing
surfaces than to serve as components of the lymphatic system.
Ordinarily the serous sacs contain only a small amount of
fluid, which acts as a lubricant ; in the synovial sacs and
bursse this fluid is much different from ordinary lymph, being
glairy and viscid and having the character of a special secre-
tion.

Origins of the lymphatic vessels: The lymph-spaces just
considered constitute the chief portion of the ultimate origins

84 THE LYMPHATIC SYSTEM.

of the lymph-vessels. The nutritive fluids, after exuding
from the blood-capillaries and bathing the tissues, accumulate
in the interstices between the cells and in the spaces in the
tissues. These spaces open directly into the smallest radicles
or capillaries of the lymphatic vessels ; or the fluids may
enter the vessels by osmosis through their thin walls. The
lacteals form another important class of lymphatic origins ; as
elsewhere described, they are small blind tubes occupying the
axis of the villi of the small intestine, and emptying into the
larger lymphatic vessels in the submucosa. They are really
lymphatic radicles or capillaries, and their special function is
to absorb into the circulation the fatty and other food-mate-
rials digested and elaborated in the alimentary canal. The
lymph-stomata, minute openings guarded by small spheroidal
cells, occurring at the points of junction of the endothelium-
cells of serous membranes, also form a sort of origin or open-
ing into lymph- vessels.

Lymphatic vessels : The lymph-vessels form a series of
channels ramifying through the entire body. The fluids from
the lymph-spaces and lacteals are taken up by the small
lymphatic branches, these combine to form larger channels,
and finally they are all united into two vessels, the thoracic
duct and the smaller right lymphatic duct, which empty into
the blood at the junction of the jugular and subclavian veins
on each side.

The smallest lymphatic vessels, the so-called lymph-capil-
laries, including the lacteals, are delicate protoplasmic tubes
made up of a single layer of polygonal endothelium-cells.
As these vessels unite and become somewhat larger, their
endothelial lining, now made up of more elongated cells,
becomes surrounded with a certain amount of connective
tissue. The smaller lymphatic channels are very delicate,
inconspicuous structures difficult to distinguish.

The larger lymph- vessels have thicker walls, and in structure
somewhat resemble the veins. Their walls are composed of
three coats. The inner coat is lined with elongated endothelium-
cells, beneath which is a thin layer of connective and elastic tis-
sue. The middle coat consists mainly of elastic tissue and in-
voluntary muscle-cells arranged transversely. The external coat,
or adventitia, is an investment of fibrous and areolar tissue.

LYMPHOID OR ADENOID TISSUE. 85

Lymphatic vessels contain numerous valves, formed by
transverse folds of the inner tunic. Associated with the valves
are alternate dilatations and constrictions of the lymphatic
vessels, which give them a characteristic beaded appearance.

The thoracic duct is the largest and best developed of the
lymphatic vessels. Its inner tunic contains a considerable
amount of subendothelial connective tissue and longitudinally
arranged elastic fibres. Its outer coat contains scattered
bundles of longitudinal involuntary muscle.

Lymphoid or adenoid tissue consists of an open connective-
tissue network, the meshes of which are crowded with free
cells, called lymphoid cells, the whole communicating with
lymphatic vessels. The connective-tissue reticulum which
forms the basis of typical lymphoid tissue has already been
described under the name retiform tissue; it consists of fine
interlacing fibrils covered or lined at their intersections with
flat stellate connective-tissue or eudothelioid cells. The
meshes formed by this structure are filled with lymphoid cells,
small free spherical cells with relatively large and prominent
deeply staining round nuclei and small cell-bodies. These are
ofteu packed in so densely as to obscure and hide the reticular
basis. The meshes communicate freely with one another and
with the interior of entering or afferent and departing or
efferent lymphatic vessels, so that the tissue forms a lymph-
space, and through it lymph constantly flows. Adenoid tissue
is also supplied with blood-capillaries.

Lymphoid tissue exhibits all gradations from diffuse masses
without definite boundaries to sharply circumscribed nodules.
Diffuse lymphoid tissue occurs imbedded in connective tissue,
and merges insensiblv into the surrounding tissues. It pre-
sents all grades from ordinary connective or areolar or even
epithelial tissue infiltrated scantily or densely with wandering
lymphoid cells to typical dense adenoid tissue with a retiform
basis.

In other cases lymphoid tissue forms well-defined nodules,
more or less spherical in shape, often quite sharply circum-
scribed by a condensation of the surrounding fibrous tissue.
Such nodules are often called lymph-follicles (Fig. 38). The
afferent lymph-vessels are said to open into the periphery
of such nodules or follicles. The tissue in the centre of the

86 THE LYMPHATIC SYSTEM.

follicles is often less dense than that at the periphery.
Lymphatic glands may be regarded as highly specialized or
compound lymph-follicles.

Fio. 38.

•

Lymph-follicle (Flemming).

Lymphoid tissue is widely distributed through the body. In
a diffuse form it is common in mucous membranes in many
situations, especially the alimentary canal. Circumscribed
lymph-follicles are most typically represented by the solitary
and agminate glands of the intestines ; also by the tonsils and
Malpighian corpuscles of the spleen. The lymphatic glands
and t hymns are also composed of lymphoid follicles.

Lymphatic glands : Interposed in the course of the lymph-
atic vessels in many situations, notably in the mesenteries,
mediastina, and under the skin in certain parts, are numerous
lymphatic glands. These are oval or kidney-shaped bodies,
of small size, with a depression at one side, the hilum, where
the bloodvessels and efferent lymph-vessels enter and leave
the gland.

The elements of lymphatic glands are sustentacular tissue,

MEDULLARY LYMPH-SINUSES. 87

afferent lymph-vessels, lymph-sinuses, dense lymphoid tissue,
efferent lymph-vessels, and bloodvessels. Two regions can be
distinguished in them, a dense peripheral region, the cortex,
and an opener central region, the medulla, which is continuous
with the hilum.

The sustentacular tissue forms a firm fibrous capsule envel-
oping the gland, which sends trabeccil&e or septa inward
toward the centre, dividing the gland into a number of radiat-
ing rounded lobules. Delicate retiform tissue, also a portion
of the sustentacular framework, fills the entire gland and
forms the basis of the lymphoid structures.

The afferent lymph-vessels are a number of vessels or
branches which enter the gland at scattered points over the
periphery, emptying into the peripheral Ivmph-sinuses.

The cortical portion of the gland is mainly made up of typical
lymphoid tissue, densely packed with lymphoid cells. It is
divided into lobules by the trabeculse, and each lobular mass
of lymphoid tissue is surrounded by a lymph-sinus. The
adenoid tissue in the outer or cortical part of the lobules
forms dense continuous masses ; but toward the centre it
breaks up into branches or columns of lymphoid tissue, called
lymph-cords, which project into the medulla and are sepa-
rated by the medullary lymph-sinuses and vessels.

The lymph-sinuses are open channels and spaces in the
retiform tissue where the lymph is more free to flow than in
the dense adenoid tissue. They consist of the same open
reticulum which forms the basis of the lymphoid tissue; but
very few lymphoid cells are contained in the meshes, so that
the lymph is afforded free passage through the open network.
Into these sinuses the afferent and efferent lymph-vessels
freely open.

These sinuses may be divided into two groups, the periph-
eral sinuses and the medullary sinuses.

The peripheral lymph-sinuses surround the periphery of the
lymphoid tissue which makes up the various lobules, and the
afferent lymph vessels open into them. They consist of a
narrow space intervening between the capsule and trabeculse
and the dense lobular adenoid tissue.

The medullary lymph-sinuses are located in the central por-
tion of the gland, and consist of branching open sinuses in-

88 THE LYMPHATIC SYSTEM.

tervening between the columns or cords of dense lymphoid
tissue, and uniting in the centre to empty into the efferent
lymph- vessels.

The cortex of lymphatic glands consists of the lobules of
dense lymphoid tissue surrounded by their lymph-sinuses.

The medulla is a smaller region in the centre, continuous
with the hilum, in which the tissue is opener. It is composed
of the medullary lymph-sinuses, the columns or cords of
lymphoid tissue, the branching bloodvessels and efferent
lymph-vessels, and some connective tissue.

The efferent lymph-vessels form in the medulla by union of
the smaller channels continuous with the medullary lymph-
sinuses, and leave the gland by the hilum.

The bloodvessels enter and leave mostly by the hilum, and
in the medulla break up into networks ; some vessels also lie
in the trabeculae.

The course of the circulation through lymphatic glands is as
follows : the lymph enters by the afferent vessels at various
points in the periphery, passes into the peripheral lymph-
sinuses, then percolates through the lymphoid tissue, is col-
lected in the medullary lymph-sinuses, and is carried away by
the efferent lymph-vessels. At the same time the blood circu-
lates through the gland, and the serum which transudes through
the capillary walls also joins the efferent stream of lymph.

Thymus gland (Fig. 39) : This is an infantile organ, situ-
ated at the base of the neck and in the upper mediastinum.
In the embryo it first appears as a downgrowth of hypoblastic
epithelium, which, dividing and subdividing, takes on the
character of a compound or racemose epithelial gland. Around
this epithelial structure soon develops from the mesoblast a
mass of lymphoid tissue in such abundance as to encroach on
the epithelial growths, causing them to atrophy and cutting
them off in detached masses, which in the mature state of the
gland appear as scattered rudimentary epithelial nodules, the
concentric corpuscles. The organ usually reaches it maximum
development at the second or third year of age, and then in
the course of ten or fifteen years gradually atrophies and
finally disappears, being in its turn replaced by fatty and
fibrous tissue

The thymus exhibits a medullary and a cortical region,

THYMVS GLAND.

and consists of a sustentacular framework, lymphoid tissue,
the concentric corpuscles of Hassall, and blood and lymphatic
vessels.

The sustentacular tissue consists of a fibrous capsule envel-
oping the gland, trabeculae extending inward dividing the
cortical portion into lobes and lobules, and a retiform frame-
work filling the entire organ as a basis for the lymphoid
tissue.

The body of the gland consists throughout of lymphoid

FIG. 39.

Lobule of thym us gland (Schafer). a, cortex; tr, trabeculae; 6, bloodvessels in the
medulla ; c, corpuscles of Hassall.

tissue, open and clearer in the central portion, thus constitut-
ing the medullary region, and dense in the outer or peripheral
portion forming the cortex.

The cortical region is divided into lobes and lobules by the
trabeculae extending inward from the capsule.

The lobular divisions do not extend into the medulla,
which thus forms a common core from which all the lobules
project.

Scattered about in the medulla are the concentric corpuscles,
or corpuscles of Hassall, small spherical bodies having a gran-
ular core surrounded concentrically by flat squamous epi-

90 THE LYMPHATIC SYSTEM.

thelioid cells, remains of the original epithelial structure of
the gland. The thyraus is abundantly supplied with blood
and lymphatic vessels.

The tonsils and solitary and agminate glands of the intes-
tines are lymphoid glands, and are described in connection
with the alimentary system.

The functions of lymphoid tissue and glands are not entirely
understood, but some important purposes which they serve
are known. They are the source of the lymph-corpuscles
and leukocytes of the blood. The lymphoid cells of adenoid
tissues, after undergoing enlargement and certain changes,
enter the efferent lymph-stream as lymph-corpuscles, and
after passing into the blood they form leukocytes. Lymphatic
glands also serve to arrest toxic and foreign bodies which
enter the lymph-stream ; their tissue acts as a sort of filter in
this respect. Thus, in cases of vaccination, carcinoma,
chancre, and many similar conditions, the virus from the
affected spot is taken up by the lymph-vessels, but is arrested
in its passage at the next group of lymphatic glands, which
swell up and become inflamed, thus for a time retarding the
progress of the disease. The interchange between the blood
and lymph circulations in the lymphatic glands may also be
associated with some sort of internal secretory process. The
special purpose of the thymus is obscure.

CHAPTER VIII.
BLOOD AND LYMPH.

The blood and lymph are the cellular fluids circulating
about the body in the circulatory and lymphatic systems and
providing for body-nutrition. They convey to the tissues
the gaseous, fluid, and solid pabulum required in their ana-
bolism or upbuilding, and bear away from them the waste-
products of their katabolism or downbreaking.

Blood: On examining fresh blood under the microscope
we observe large numbers of free straw-colored cells, with
here and there a colorless cell, suspended in a clear homo-
geneous fluid. The blood, then, consists of two portions — a
fluid .portion, the plasma, and free blood-cells or corpuscles
suspended in it.

The corpuscles, again, are of three kinds — red blood-corpus-
cles, white blood-corpuscles, and blood-plates.

The plasma comprises about three-fifths of the blood ; the
corpuscles about two-fifths.

The blood may be regarded as a fluid tissue, the corpuscles
being the cellular elements and the plasma the intercellular
substance. It differs from other tissues, however, in that the
intercellular portion is not produced by the activity of the
blood-cells themselves, but is derived from absorption. The
blood belongs to a class of tissues that is sui generis, different
from and coordinate with the classes of epithelium, connec-
tive tissue, etc., which make up the fixed tissues. Owing to
the facility with which it can be examined and the significant
changes which it exhibits in various diseases, the histology of
the blood is a matter of great importance in practical medi-
cine.

Blood-plasma, or liquor sftnguinis: This is a clear, homogene-
ous, colorless fluid comprising about three-fifths of the volume
of the entire blood. It consists of water holding in solution

92 BLOOD AND LYMPH.

about 9 per cent, of albuminous substances, mineral salts,
and other constituents. These substances serve as pabulum
for the nourishment of the tissues. It readily undergoes
coagulation, separating into clot and serum. The plasma
originates by absorption from the alimentary tract. Being
homogeneous, it ordinarily exhibits no structural features to
the microscope; its composition is a matter for chemical
study.

Under certain circumstances, however, substances or par-
ticles visible to the microscope appear in the plasma. After
standing for some time specimens of fresh blood exhibit in
the plasma numerous delicate colorless straight filaments of
fibrin interlacing and running in different directions; they
often radiate from points or centres, and at these centres
blood-plates are often situated. These filaments consist of
fibrin which has undergone coagulation. The plasma under
the microscope often has a yellow tinge, due to haemoglobin
dissolved out of the red corpuscles.

Rhombic crystals of haemoglobin appear in blood under
proper conditions or treatment. Small particles of fat are
sometimes present in the plasma, especially after a fatty
diet.

In the blood-plasma are frequently to be seen minute
granules, or "blood-dust," both in normal and abnormal
conditions. Ordinarily they are not numerous, but occur
singly here and there. Some of these may be particles of
fat, or foreign particles accidentally introduced. In most
cases, however, they seem to be minute bits of protoplasm,
or neutrophile or oxyphile granules extruded from leuko-
cytes ; their nature is not yet fully determined. These are
very minute in size, variable in shape, colorless and refractile,
and are in constant very active oscillating or Brownian move-
ment.

Red blood-corpuscles (Fig. 40) are also called erythrocytes,
and, most appropriately, colored blood-corpuscles.

The red blood -corpuscles of man are circular disc-shaped
cells, between 7 and 8 /j. in diameter (averaging 7.5 /./), and
about 2 p. thick. They are biconcave, and thinner in 'the centre
than at the edges, so that their color is lighter and paler in
the middle and deepens toward the periphery. In appearance

RED BLOOD-CORPUSCLES. 93

they are homogeneous throughout, and they possess no cell-
envelope. They contain no nuclei, except in early embryonic
life and in abnormal conditions. Their color, when seen
singly or in thin layers, is not red, as the name indicates, but
a characteristic pale yellow with a slight greenish tinge ; it is
only in mass that they produce the effect of red color. They
are soft, elastic, pliable, almost gelatinous. As they flow
through the capillaries or move in currents in the micro-
scopical specimen they change shape with the least pressure,
and may become greatly distorted ; but on release from re-
straint they resume their normal discoid shape.

The number of red corpuscles in given volumes of blood
under similar normal conditions is practically constant, and
near the sea-level in adult males
is about 5,000,000 in each cubic FIG. 40.

millimetre of blood ; in females,
about 4,500,000. In very vigor-
ous individuals the number of
red corpuscles may be increased,
even up to 6,000,000; while
with increase of altitude above
sea-level there is a very marked
increase in their number.

When a drop of blood is
placed under the microscope the
red corpuscles are observed to

i ., ., l (> ,. i Red blood-corpuscles of man. a, sur-

exhlblt, for a time, a tendency face view of normal corpuscles;

to form rouleaux-that is, they kgg^&SSr&S?^
become arranged or adherent —; &££» ;<— ^g

together evenlv Side DV Side, of broken corpuscles ; g, bent and

Ti «T /» . distorted corpuscles: h. swollen

like a pile OI COins. and decolorized corpuscle.

Crenation : The red corpuscles

are so delicately adjusted to the blood-plasma that they are
very easily affected as to shape by any alteration in the
density and composition of the medium in which they occur.
One of the commonest of these change's is crenation. This
consists of a shrinkage of the corpuscle, which loses its dis-
coid shape and becomes spheroidal or irregularly distorted,
while at the same time minute rounded or spiny projections
appear on the surface ; of these spines there may be only one

O-C ; •

94 BLOOD A.\D LYMPH.

on the entire corpuscle, or only a few ; or a large number
studding the surface of the much-shrivelled spherical cell.
The more the cell is contracted the greater is the number of

spines.

Crenation is caused by contraction of the corpuscle from
loss of part of its fluid contents through osmosis, and occurs
when the density of the plasma is increased by evaporation
from exposure to the air or by the addition of saline or other
substances.

Other changes of form : When the density of the plasma
is diminished, as by the addition of water, the red corpuscles
through osmosis absorb fluid, swell, and become spherical, and
at the same time lose their color, the haemoglobin in the
corpuscles leaving them and passing into solution in the
plasma outside.

Sometimes the substance of the corpuscles shrinks, leaving
artificial empty spaces or vacuoles.

In squeezing blood from a puncture in the skin, portions of
the corpuscles are often broken off, and, assuming a rounded
form, appear like diminutive corpuscles.

At other times the corpuscles appearyferer?, twisted, or doubled
up in the form of a hemispherical bowl.

Familiarity with the changes of form which red corpuscles
undergo under changed conditions is necessary to avoid mis-
taking them for morphologic or pathologic abnormalities.

In various disease-conditions interesting variations from the
normal are exhibited by red corpuscles, as the presence of
nuclei, and abnormalities in size, coloration, and consistency.

The function of the red blood-corpuscles is to convey oxygen
from the lungs, whSre it is taken up by the hemoglobin, to
the tissues, where it is given out for nutritive purposes.

In structure they appear to consist of a pliable and elastic
colorless proteid stroma, in which haemoglobin is suspended in
solution ; the form and consistency of the cells are due to the
stroma, the color, to the haemoglobin. They do not exhibit
ameboid movement or cell division. Considering their lack
of nuclei, and of other vital properties, the red blood-corpus-
cles must be regarded as a very degenerate form of cell,
exhibiting few characteristics of vitality and serving the
purely mechanical purpose of carrying oxygen.

DEGA Y OF RED BLOOD-CORPUSCLES. 95

The origin of red blood-corpuscles is not fully determined.
The earliest red corpuscles of embryonic life originate along
with the bloodvessels from mesoblastic cells (" angioblasts ")
which form a protoplasmic network, in the substance of
which, and especially at the intersections, nuclei proliferate
and accumulate. These masses of multinucleated protoplasm
break up, becoming converted into cavities filled with sepa-
rated cells; the peripheral protoplasm and nuclei form an
endothelial lining to the cavity, which is now an incipient
bloodvessel, while the central mass of nucleated protoplasm
separates into amoeboid nucleated cells, which then acquire
haemoglobin and become nucleated red blood-corpuscles.
From these fi blood-islands " the process of vessel and cor-
puscle formation proceeds along the protoplasmic strands.

Thus the earliest embryonic red corpuscles are nucleated,
and capable of self-reproduction by indirect division ; these,
however, soon disappear, and are replaced during the remain-
der of life by non-nucleated corpuscles.

The most probable source of red corpuscles in the adult
seems to be the bone-marrow. As described above, bone-
marrow contains an ample network of expanded vascu-
lar sinuses, and one class of the cells of the marrow
consists of the erythroblasts, small nucleated haBmoglobin-
containing cells capable of amoeboid movement. The red
corpuscles are probably produced from these cells, but in
what manner is not known ; the erythroblasts themselves may
perhaps be descendants of the nucleated red corpuscles of the
embryo, continued in existence by repeated division.

Other theories of the origin of red corpuscles have been
presented, as that they are produced from leukocytes, or blood-
plates, or in the spleen, lymphatic glands, or thy m us, but
these suppositions have not been well substantiated. There
is a constant destruction of erythrocytes, and a means some-
where in the body by which they can be actively renewed.
They cannot reproduce themselves by division ; and the only
known seat for their formation supported by any great
probability is the bone-marrow.

Decay of red blood-corpuscles : Erythrocytes, like all other
living cells, pass through a life-cycle of development, matur-
ity, decay, and death. The red corpuscles seen in normal

96 BLOOD AND LYMPH.

blood are all perfect and show no visible signs of degenera-
tion. What becomes of them when they decay and how they
are removed from the circulating blood is not entirely known,
but it is supposed that the spleen and liver, especially the
former, are important agents in their removal and destruc-
tion.

Differences in vertebrate red blood-corpuscles : Red corpus-
cles occur only in the blood of vertebrates, that of inverte-
brates containing only colorless corpuscles. The different
classes of vertebrates exhibit differences in the characters of
the erythrocytes with regard to shape, nucleation, and size.
All mammals, like man, have non- nucleated biconcave circu-
lar red corpuscles, except the camel family, in which they are
elliptical (and non-nucleated). In the birds, reptiles, am-
phibians, and fishes, the red corpuscles are elliptical, nu-
cleated, and biconvex (the nucleus causing an expansion of
the corpuscle), except in the cyclostomata or lampreys among
fishes, whose corpuscles are circular.

As to size, the erythrocytes of mammals are the smallest,
those of amphibians the largest.

Among mammals the red cell of the elephant is the largest
(9.2 // in diameter), that of the musk-deer the smallest ; and
it is the smallest known of all animals (2.5 //). Human
erythrocytes are among the largest of those of mammalia.
The erythrocytes of birds and fishes are much the same in
size; the corpuscle of the fowl is about 12 /j. long, of the
pigeon 15 //, of the carp 13 p. The frog's red corpuscles are
about 16 by 22 /Jt; those of the amphibian proteus 35 by 58
//. ; while those of the amphibian amphiuma are about 46 fj.
wide by 77 // long, the largest known, and visible to the
naked eye.

The number of the erythrocytes is in general in an inverse
proportion to their size, the smaller cells occurring in greater
numbers ; thus, the red corpuscles of the frog number only
404,000, those of the proteus 36,000 to the cubic millimetre.
Owing to this inverse relation of number and size the total
mass of corpuscles in equal volumes of blood is somewhat
equalized ; but the greater the number of corpuscles the
greater is their total surface ; and the greater their surface (as
in birds) the more active is the metabolism.

STRUCTURE OF LEUKOCYTES. 97

White blood-corpuscles (Fig. 41) or leukocytes, are most
appropriately, perhaps, called colorless blood-corpuscles. The
leukocytes of man are of several varieties, differing in some
particulars but similar in their general characteristics.

In shape when at rest they are spherical, but during their
amoeboid movements they are irregular and changing in
form.

In size the different varieties range from about 7 to 15 /u in
diameter, averaging about 10 fj. ; they are thus somewhat
larger than the erythrocytes. They are colorless, refractile,
and granular in appearance.

Their surface is somewhat adhesive (unlike the red corpus-
cles), so that they adhere to the glass in microscopical prepa-
rations, and in the blood-current they roll slowly along at
the edge of the stream on the wall of the bloodvessel.

Thev are of firmer consistency than the red corpuscles, and
their form is not so easily affected by mechanical influences
or changes in their environment. If the density of the fluid
in which they occur be much increased, as by the addition of
salts, they shrivel somewhat; while if the density be dimin-
ished by dilution with water, they assume the resting spheri-
cal form, become swollen, and within them appear coarse
protoplasmic granules which often exhibit the Brownian
movement.

The number of leukocytes under normal conditions is about
7500 or 8000 in each cubic millimetre of blood ; the number is
greater in young children and during pregnancy ; and during
digestion, as three or four hours after a proteid meal, their
number is normally increased about one-third (the "digestion
leukocytosis "). The leukocytes are therefore far less numer-
ous than the red corpuscles, the ratio being normally about 1
white to 600 red. In pathological conditions the number of
leukocytes may vary widely. Leukocytes do not occur in
circulating blood alone, but are also met with as lymph-cor-
puscles in the lymphatic system ; as wandering cells in the
connective tissues ; in enormous accumulations in pus as pus-
corpuscles, etc.

The structure of leukocytes is that of typical actively vital
cells. They have a cell-body of active protoplasm, well-
marked nuclei, and are said to be provided with centrosomes,

7— Hist,

98 BLOOD AND LYMPH.

They have no observable cell-wall, other than some condensa-
tion of the peripheral protoplasm.

The nuclei vary in the different varieties of leukocytes as
to number, form, size, and staining properties. The " mono-
nuclear" leukocytes contain a single nucleus each. Other
varieties when stained appear to contain about three separate
rounded nuclei ; but some authorities at present consider that
in the living state these nuclei are in most cases connected by
strands of the nuclear substance, thus forming a single very
irregular nucleus rather than three separate nuclei. The
possession by a leukocyte of several distinct (or multiple)
nuclei is indicated by the term " polynuclear " ; while the
possession of single variable and irregular (or multiform)
nuclei is designated by the term " polymorphonuclear."

Inform the nuclei range from spherical, through horseshoe-
shaped forms, to exceedingly irregular and variable coiled and
twisted shapes. Their size varies from those that are large
and occupy the largest part of the cell to those that are rela-
tively smaller.

The nuclei take nuclear and basic stains with more or less
avidity ; the smaller nuclei, in which the chromatin is more
concentrated, usually stain intensely ; \vhile the larger nuclei,
whose chromatin is more diffused, are less deeply colored.

The cell-bodies of leukocytes consist of actively vital pro-
toplasm. Sometimes, especially during amoeboid movement,
two parts can be distinguished in the body-protoplasm, a clear
homogeneous hyaline peripheral portion, the hyaloplasm, and
a less clear granular portion in the interior of the cell, the
granuloplasm. Well-marked granules are present in the
bodies of some varieties of leukocytes, absent from others.
The granules mostly found are fine neutrophile granules and
coarse oxyphile granules (e and « granules of Ehrlich's classi-
fication) ; fine basophile (8) granules also occur but are incon-
spicuous. In the living state the granular appearance of the
leukocytes often obscures the nuclei ; but on treatment with
acetic acid the granules disappear, the cell-body becomes clear,
and the nuclei stand out prominently as about three spherical
bodies.

Varieties of leukocytes : According to variations in size,
nuclei, granules, and staining-properties, the leukocytes of

TRANSITIONAL LEUKOCYTE.

normal human blood are divided into five classes, namely :
small mononuclear, large mononuclear, transitional, poly-
nuclear (or polymorphonuclear), and eosinophile.

FIG. 41.

Leukocytes of human blood, a, small mononuclear leukocyte, stained; 6, large
mononuclear leukocyte, stained; c, transitional leukocyte, stained; d, e, , poly-
morphonuclear or ne'utrophile leukocyte, living appearance, showing distinc-
tion of hyaloplasm and granuloplasm and amoeboid movement ; /, polymorpho-
nuclear leukocyte, in fresh state, treated with acetic acid ; g, h, i, polymorpho-
nuclear leukocyte, stained; k, eosinophile leukocyte, living appearance; I,
eosinophile leukocyte, stained.

The small mononuclear leukocyte, or small lymphocyte, is
about 6 to 8 micromillimetres in diameter (about the same as
red corpuscles), and has a single large spherical, deeply stain-
ing nucleus, surrounded by a small amount of faintly-stain-
ing non-granular protoplasm, which forms a small cell-body.
Morphologically and genetically it is similar to or identical
with lymph-corpuscles.

The large mononuclear leukocyte, or large lymphocyte, the
largest corpuscle of normal blood, is 12 to 15 micromillimetres
in diameter, contains a single, very large, rounded nucleus
that does not stain very deeply, and has a large body of non-
granular, faintly staining protoplasm. Sometimes no sharp
line can be drawn between this and the preceding class, all
intermediate gradations of size and coloration being present.

The transitional leukocyte is like the large mononuclear

100 BLOOD AND LYMPH.

form, except that its single large nucleus, instead of being
spherical, is more or less indented at one side, tending toward
a horseshoe shape ; the body-protoplasm also sometimes con-
tains a few fine granules. In the shape of its nucleus it is an
intermediate form between the large mononuclear and the
polymorphonuclear variety. It is, however, closely related to
the former, all gradations being present so that a sharp line
can scarcely be drawn between the large mononuclear and the
transitional ; on the contrary (especially with respect to the
absence of granules), there is a sharp gap between the transi-
tional and polymorphonuclear varieties not filled by inter-
mediate gradations. Transitional leukocytes are often to
be regarded simply as a variety of the large mononuclear
group.

The polymorphonuclear, polynuclear , or neutrophile leukocyte
is about 10 micromillimetres in diameter, has a large cell-
body of active protoplasm, containing large numbers of fine
neutrophile (s) granules, and a very variable, irregularly
shaped, deeply staining nucleus. Often, especially after the
action of reagents, the nucleus appears to consist of about
three separate, rounded nuclei ; whence until recently the term
polynuclear was the prevalent designation of this leukocyte.
At present the opinion is gaining ground that in most cases,
instead of three separate nuclei, the living corpuscle contains
one long twisted and irregular nucleus, so that the name poly-
morphonuclear is now considerably used. This is the most
active and much the most abundant variety of leukocyte in
the blood, and is also the form found in pus. It exhibits
active amoeboid movements, and the distinction of hyaloplasm
and granuloplasm in its body can often be made out.

The eosinophile (or oxyphile) leukocyte is about 10 /2 in
diameter; its nucleus, except that it stains less deeply, is
similar to that of the polymorphonuclear variety, being poly-
morphous and irregular, or perhaps multiple ; the body-proto-
plasm is crowded with conspicuous coarse spherical oxyphile
or eosinophile (a) granules. In microscopical specimens the
granules surround but do not overlie the nuclei, leaving the
latter as clear spaces. This leukocyte has a striking appear-
easily recognized, both in the living and stained
fe^the least common variety in the blood. Its

i :_.
BRA

PROPERTIES AND FUNCTIONS OF LEUKOCYTES. 101

wall is weak and easily ruptured, as the granules often ap-
pear spreading out into the surrounding plasma without any
definite boundary. Intermediate forms between the eosino-
phile, the polymorphonuclear, and the mononuclear leukocytes
are conspicuously absent from the blood.

These different varieties of leukocytes occur in normal
blood in tolerably constant proportions to one another, aver-
aging about as follows :

Small mononuclear leukocytes 22 per cent.

Large mononuclear and transitional leukocytes 6 " "

Polymorphonuclear leukocytes 70 " "

Eosinophile leukocytes 2 " "

100

Occasionally a stray mast-cell finds its way into the blood.
Variations from the normal occur in morbid conditions ; the
total number of leukocytes and the relative number of the
different varieties may be altered, or entirely new forms of
leukocytes (myelocytes) may appear.

Vital properties and functions of leukocytes : Leukocytes are
typical cells, undifferentiated and independent, actively en-
dowed with all the essential attributes of vitality. They are
capable of undergoing division, direct and indirect. They
(especially the polymorphonuclears) exhibit active auioaboid
movements, which enable them to make their way through
the walls of the capillaries and wander about in the tissues.
By means of their amoeboid movements they also have the
power of surrounding and engulfing within their protoplasm
foreign particles and living parasites, bacteria and protozoa.
This process is called phagocytosis, and cells which engage in
it are called phagocytes.

The act of phagocytosis can sometimes be observed under
the microscope, as in connection with the malarial protozoon,
and is a remarkable and interesting sight. The leukocyte
seems capable of recognizing the presence and whereabouts
of the parasite at a distance of many times its own diameter,
and moves upon it directly and with distinct purpose, pushing
the red corpuscles aside. By protruding pseudopodia toward

102 BLOOD AND LYMPH.

the parasite and drawing itself up behind, it advances with a
mode of locomotion resembling that of a snail. Finally, it
sends processes around the parasite and engulfs the latter in
its body, where it is disintegrated. The leukocyte seems en-
dowed with intelligence, purpose, and a separate individuality
of its own, vividly analogous to the psychic manifestations of
macroscopic animals.

Chemical substances are supposed to have an influence on
leukocytes, some attracting them, others repelling them ; this
is called chemotaxis. Positive chemotaxis consists in the attrac-
tion of leukocytes toward certain substances, negative chemo-
taxis in their repulsion from other substances.

The functions of leukocytes are not entirely understood.
One important purpose which they are believed to subserve
is the removal and destruction of foreign noxious substances
and parasites, by phagocytosis; they also play an active part
in the repair of injuries, in immunity, and the resistance and
reaction of the body to morbid processes.

Origin and development of leukocytes : The small mononu-
dear leukocytes are doubtless derived from the free lymphoid
cells which crowd adenoid tissues ; these undergo development,
enter the lymph-stream, and are thence carried into the blood.

The large mononuclear and transitional leukocytes appear to
develop from the small mononuclears, as intermediate grada-
tions between them are to be found in the blood.

The source of the polymorphonuclear and eosinophile leuko-
cytes is not so obvious. They may develop from the mononu-
clear variety — or, as has been suggested, the eosinophiles
(" old " forms) may develop from the polynuclears, and the
latter ("adult" forms) from the mononuclears (" young "
forms) ; as, however, there are no intermediate forms between
these varieties in the circulating blood, their development
from one another must take place, if at all, somewhere in the
viscera. Or perhaps the polynuclear and eosinophile leuko-
cytes originate independently in some of the viscera, as the
spleen or bone-marrow.

The eosinophiles, especially, may not improbably develop
in the marrow, as in the latter are found similar cells contain-
ing oxyphile granules. Division of the developed leukocytes
themselves may be a partial means of their production.

LYMPH. 103

Blood-plates are also called blood-plaques or platelets, cor-
puscles of Bizzozero, and haeruatoblasts (Fig. 42). These are
small, colorless, hyaline,
homogeneous bodies, of
spherical or discoid shape, -.%::

between 2 and 4 micromil-
limetres in diameter, num-
bering 200,000 to 400,000
in each cubic millimetre of
normal blood. On exposure
to the air they quickly dis-
integrate and disappear, so
that special precautions are Q

necessary in taking a speci- Blood-plates.

men of blood to preserve

them. They occur singly, or often grouped together, in the
vicinity of granular matter, probably the debris of disinte-
grated ""plaques. They often form centres from which fila-
ments of coagulating fibrin radiate, and they may have some
relation to the coagulation of the blood. They have been
called hnematoblasts under the idea that they are developing
forms of red blood-corpuscles, a supposition that has not been
confirmed. Their origin, purpose, and significance are not
definitely known.

Lymph, the fluid which flows in the lymphatic system, con-
sists of a fluid, the serum or plasma, suspended in which are
free cells, the lymph-corpuscles, and particles of fat. The
plasma, or liquor lymphae, is similar to that of the blood.
The lymph-corpuscles are leukocytes, like those of the blood.
Some of them are white corpuscles that have migrated from
the capillaries and been taken up from the tissues by the
lymph-stream ; large numbers of them, however, are of the
small mononuclear type, and are lymphoid cells carried out
of the adenoid tissues through which the lymph-currents pass.
The chyle is that portion of the lymph that is collected in the
lacteals and intestinal lymphatics ; it is of the nature of an
emulsion, opaque and white, from the presence in the plasma
of large numbers of minute particles of fat absorbed from
the intestines.

CHAPTER IX.
BLOOD-GLANDS AND DUCTLESS GLANDS.

THE lymphoid glands pertaining to the lymphatic system
(lymphatic glands, tonsils, thymus, solitary and agminate
glands, etc.), are described elsewhere.

Other structures, "blood-glands," bear the same relation to
the blood-stream that lymphatic glands do to the lymph stream.

Of these the chief representative is the spleen, an important
gland partaking somewhat of the lymphoid type. In some
mammals other blood-glands occur, the " haemal glands."
Bone-marrow, in structure and function, forms a sort of u blood-
gland." Of similar nature, perhaps, are the small coccygeal
and carotid glands.

The active ductless glands of the secretory or epithelial
type are the thyroid, parathyroid, adrenal, and pituitary bod-
ies ; besides these are the ovary (which is. of unique type), the
rudimentary pineal body, and certain atrophic foatal structures
about the genital organs, as the paradidymis and parovarium.

The functions of all these structures are more or less obscure,
but (especially if the theory of internal secretion is true) they
may be considered as probably belonging, in common, to the
haemapoietic (blood-forming) and hsemolytic (blood-destroying,
blood -purifying) system, contributing corpuscular and chemi-
cal constituents to the blood or removing from it effete
materials.

The Spleen.

General structure : The spleen (Fig. 43) consists of a pulpy
parenchyma supported in a reticular sustentacular tissue ;
contains numerous lymphoid follicles (Malpighian corpuscles),
and is freely supplied with bloodvessels opening directly into
the reticular spaces. The outermost covering of the spleen
is formed by the peritoneum.

104

THE SPLEEN.

105

The sustentacular or connective-tissue framework of the
spleen consists of a firm fibrous capsule enveloping the organ ;
of fibrous trabeculse or septa, continuous with the capsule,
traversing the organ in all directions and dividing it into small
compartments or lobules ; and of an open reticular tissue
filling these compartments. This reticular tissue, which is
of similar character to the retiform basis of lymphoid tissue,
consists of fibres interlacing to form open communicating
spaces or sinuses, wrhich are incompletely lined with stellate
flat endothelioid connective-tissue cells. These spaces open
directly into the bloodvessels, and, filled with free cells of
various kinds, form the splenic pulp.

Scattered involuntary muscle-cells occur in the capsule and
larger trabeculae.

The ample bloodvessels of the spleen enter at the hilum,

FIG. 43.

Portion of spleen, a, capsule ; 6, trabecula ; c, splenic pulp; </, Malpighian
corpuscle ; e, portion of artery.

and the larger branches lie in the trabecular tissue as they
ramify through the organ. The terminal arteries and veins,
instead of being connected by capillaries, open into the reti-
form sinuses making up the splenic parenchyma, so that the
blood-current percolates through this spongy tissue in its pas-

106 BLOOD-GLANDS AND DUCTLESS GLANDS.

sage from artery to vein. Toward the terminations of the
bloodvessels, openings appear in their walls, and the vessels
become lost in the sinuses, the endothelium of the tunica
intima merging into the flat connective-tissue cells incom-
pletely lining the reticulum.

The parenchyma of the spleen is mostly made up of the
splenic pulp. This consists of the open network of sinuses
filled with plasma and free cells, some of which are peculiar
to this situation, others derived from the blood-stream passing
through. The free elements of the pulp are : red blood-cor-
puscles in great abundance ; lymphoid cells and leukocytes of
all kinds ; large multi nucleated amoeboid granular cells ; and
pigment-granules, free or within the leukocytes and amoeboid
cells, derived from the disintegration of the hemoglobin of
broken-down red blood-corpuscles.

The spleen is supplied with lymphatic vessels, which are
much less conspicuous than the blood-supply.

Scattered about through the substance of the spleen are
numerous spherical or oval nodules or follicles of typical
lymphoid tissue, the Malpighian corpuscles. These occur sur-
rounding small-sized arteries, which pierce them at or near
their centres.

The function of the spleen is not thoroughly understood ;
it is concerned with the formation or purification of the blood.
It may be a seat for the removal of worn-out red blood-cor-
puscles. Whether it contributes any corpuscular elements to
the blood has not been settled.

The coccygeal gland (Luschka's gland) is a small, round
pea-sized body, near the tip of the coccyx, in which the
middle sacral artery terminates. It consists of a plexus of
dilated capillaries, or even cavernous blood-sinuses, which
are surrounded by masses of granular polyhedral connective-
tissue cells. The gland is enveloped by a fibrous capsule,
from which trabeculaB pass into the interior. It is plentifully
supplied with nerves. Its function is unknown.

The carotid glands are small bodies situated in the bifurca-
tion of the common carotid arteries, one on each side. Their
structure is similar to that of the coccygeal gland.

THE THYROID GLAND.

The Thyroid Gland.

107

At an early embryonic period this gland opens into the
pharynx by an outlet-duct ; but this soon disappears, leaving
the alveoli isolated and ductless.

The sustentacular connective tissue of the gland consists of
a firm fibrous capsule enveloping the organ ; trabeculce or septa
(interlobular), of similar fibrous tissue, which divide the gland
into lobes and lobules ; and a delicate inter alveolar or intra-
lobular tissue between and supporting the secretory alveoli.

The glandular alveoli are spherical or oval saccules, without

FIG. 44.

Alveoli of thyroid gland (Dunham).

outlet-ducts and entirely closed and isolated from one another
(Fig. 44). They are lined with a single layer of cuboidal
epithelium-cells with prominent nuclei. The cavities or
lumina within the alveoli are of considerable size, are filled
with secreted colloid substance, and their margins often have a
scalloped appearance.

The bloodvessels of the thyroid are exceedingly ample, and
distribute a rich capillary network about the saccules.

108 BLOOD-GLANDS AND DUCTLESS GLANDS.

The lymphatics are also abundant, and through them the
secretion of the gland is probably removed.

The function of the thyroid, as indicated by its rich blood-
supply and by the serious consequences of loss of the organ,
is of great importance. Its secretion is entirely " internal/'
and by its action metabolism and cell-life are stimulated and
hastened, obesity diminished, circulation is affected, and the
cerebrum stimulated.

The parathyroids are small oval ductless glands about 6 to
10 mm. long, situated near the thyroid, usually two on each
side. They are enveloped by delicate fibrous tissue, and the
epithelial columns and alveoli are separated by delicate tra-
beculaB of similar tissue. The connective tissue is very vascu-
lar. The parenchyma of the parathyroid bodies consists of
polyhedral glandular epithelium-cells arranged in branching
solid columns or hollow tubes, some of which occasionally
contain secreted colloid material. The epithelium consists
mainly of clear cells with large nuclei, not dissimilar to the
cells of the thyroid gland. A few of the epithelial alveoli,
however, consist of larger cells with granular oxyphile bodies,
which look much like liver-cells ; these cells are altogether
different from those in the thyroid, and would seem to estab-
lish the individuality of the parathyroids as structures inde-
pendent and distinct from the thyroid.

Little has yet been definitely ascertained as to the functions
of the parathyroids, nor their genetic or vicarious relations to
the thyroid.

The Adrenal or Suprarenal Glands.

General structure : These are ductless bodies made up of
columns and" masses of epithelium supported in sustentacular
tissue, and abundantly supplied with bloodvessels and nerves
(Fig. 45). The substance of the gland exhibits two parts,
the cortex or peripheral portion, and the medulla or central
portion.

The sustentacular connective tissue consists of a fibrous
capsule enveloping the gland, and more delicate connective
tissue permeating the interior and lying between the epithelial
masses and vessels.

THE ADRENAL OR SUPRARENAL GLANDS.

109

FIG. 45.

The cortex consists of columns or nodules of epithelium
(mostly without lamina), separated by delicate vascular con-
nective tissue. The epithelium-cells are polyhedral, granular,
and sometimes contain fat-
particles. According to the
arrangement of the epithelial
masses, the cortex is divided
into three zones : the zona re-
ticularis, zona fasciculata, and
zona glornerulosa, from with-
in outward.

The zona reticularis, the
innermost zone, consists of a
network of epithelial columns
anastomosing with one an-
other. In the zona fascicu-
lata, which comprises the
largest part of the cortex, the
epithelial columns are straight,
parallel, radiating, and sepa-
rate from one another. In
the zona glomerulosa, w7hich is
next to the capsule, the epi-
thelial columns are apparently
coiled and convoluted, ap-
pearing on section as separate
rounded nodules.

Capillaries and lymph-pas-
sages are abundant in the inter-
columnar cortical tissue, in
close relation with the epi-
thelium-columns, which pos-

, Section of

sess no basement-membranes. (Eberthi.

The medulla of the adrenals

is quite distinct from the cortex and consists of epithelial
masses and abundant bloodvessels, lymphatics, and nerves,
supported in delicate connective tissue. The epithelium is
arranged in branching and anastomosing nodules and columns
or closed tubes ; the cells are polyhedral or columnar. Capil-
laries are numerous and large venous sinuses are present.

human adrenal gland
(Eberth). 1, cortex; 2, medulla.

110 BLOOD-GLANDS AND DUCTLESS GLANDS.

Nerve-fibres and small nerve-cells are abundant in the
medulla.

The medullary portion of the adrenals is said to be of epi-
blastic origin, an outgrowth from the primitive spinal cord,
while the cortex is derived from the mesoblast.

The internal secretion of the adrenals seems to be a power-
ful constrictor of the bloodvessels and is also probably a
nervous stimulant. The organ is by some regarded as a part
of the nervous system.

The pituitary body (hypophysis cerebri) : The posterior lobe
of this body is a nervous and fibrous structure, derived from
and a part of the brain. The anterior lobe of the pituitary is
of the nature of an epithelial ductless gland, being embry-
onically an epithelial outgrowth from the primitive pharynx,
which is afterward cut off. It consists of columnar, closed
tubular, or rounded acini of polyhedral epithelial cells, sepa-
rated by fibrous septa. The acini are solid or a few may
possess lumina containing colloid material. Most of the cells
have clear bodies, but some are granular and oxyphile.

The pituitary is supposed to produce an internal secretion
which has some influence on metabolism, as disease of it
seems to be associated with peculiar anomalies of growth
(acromegaly).

The pineal body (epiphysis cerebri), a small body near the
corpora quadrigemina, has the structure of a ductless gland,
but is probably a rudimentary sense-organ. It consists of a
number of rounded acini lined by epithelium cells, separated
by and embedded in fibrous tissue. The acini contain gritty
particles of earthy phosphates, the " brain-sand," or " acer-
vulus cerebri.7'

CHAPTER X.
THE ALIMENTARY SYSTEM.

THE alimentary tract is an apparatus in which food, the
crude material of which the organism is built up, is received
and digested by the action of various secretions, the elab-
orated products absorbed into the circulation, and the
detritus discharged. It is a complex mechanism with many
varied parts and functions, all working harmoniously to-
gether. It consists essentially of a long coiled muscular
tube, the alimentary canal, opening at each end on the surface
of the body, the walls of which contain glandular structures
which secrete fluids and pour them into the canal to act on the
raw food-materials, so as to fit them for absorption and nutri-
tion. They also contain absorbent vessels by which the
digested and elaborated food is introduced into the circulation.

The different parts and organs of this system are the mouth ;
teeth ; tongue ; salivary glands ; tonsils ; pharynx ; oesophagus ;
stomach ; small intestine ; large intestine ; rectum and anus ;
peritoneum ; liver and gall-bladder, and pancreas.

The Mouth.

The lining of the mouth consists of mucous membrane,
which over the lips, floor of the mouth, cheeks, and soft
palate rests upon the voluntary muscles in those situations ;
and over the bony parts, the maxillary and palate bones, rests
upon the periosteum.

The mucous membrane of the mouth is continuous with that
of the pharynx and tongue and with the skin, and in structure
is similar to the latter. It consists of an epithelial lining, a
tunica propria, and submucosa.

The epithelial layer is the representative of the epidermis
of the skin, and consists of stratified squamous epithelium.

ill

112 THE ALIMENTARY SYSTEM.

The lower or germinal cells are rounded and spheroidal, but
as the layers approach the surface the cells become gradually
flatter and more squamous in character. This layer is very
similar to the Malpighian layer of the skin. On its free
surface the squamous cells approach a hard and horny condi-
tion and form an imperfect representative of the stratum
corneum of the epidermis.

The epithelial layer rests on the tunica propria, a firm
fibrous connective-tissue structure entirely analogous to the
corresponding layer of the cutis vera. The outer surface of
the tunica propria, as in the skin, is thrown up into numerous
small rounded elevations, or papUlce, projecting upward into
the epithelium ; the intervals between the papillae are filled
with epithelium-cells.

The submucosa consists of a variable amount of areolar and
connective tissue extending from the tunica propria to the
underlying structures. It contains numerous small racemose
mucous glands, whose ducts open on the surface of the
mucous membrane. Diffuse h/mphoid tissue is present in the
submucosa in places, especially in the vicinity of the fauces.

The Teeth.

General structure : The teeth present three divisions : the
crown, projecting above the gum;- the fane/, buried in
the gum; and the neck, at the junction of the two (Figs. 46
and 47).

Each tooth is made up chiefly of dentine, which is covered
on the crown by enamel and on the fang by crusta petrosa or
cement. The interior of the tooth is a cavity inclosed by the
dentine, called the pulp-cavity, filled with a soft tissue
or pulp.

The enamel is of epiblastic and epithelial origin ; the den-
tine and crusta petrosa are forms of connective tissue and are
of mesoblastic derivation.

The fangs of the teeth rest in sockets of the jaw-bones
lined by the periodontal membrane, which thus separates
the tooth from the bone. This membrane is a vascular
fibrous structure continuous with and similar in structure to
the periosteum of the maxillary bones ; it possesses transverse

THE TEETH.

113

fibres, like the fibres of Sharpey, which penetrate both the
boiK.- and the crusta ]- i short distance and hold the

teeth firmly in place.

The enamel of the teeth is a very hard mineral (calcareous)

. 46.

tiou of tooth in situ (Waldo. wl ; 2, dcntint ; ; ^fta petrosa ;

xillarybone; c, pulp-ca\it>.

8— Hi?t.

114

THE ALIMENTARY SYSTEM.

which

substance, almost entirely free from organic matter, win
invests the crown. It is disposed in slender stra.ght or
slightly wavy rods or prisms, of about six sides each, which
are in general perpendicular to the surface of the dentine, and

. Jo, rr<i _ ._J, ,«l,:UU £nn ^T-ancvprsP

are held together by cement.

FIG. 47.

The rods exhibit fine transverse
markings. At eruption and
until worn off by attrition the
enamel is covered with a thin
epithelial cuticle, the mem-
brane of Nasmyth, the remains
of the enamel-organ.

The crusta petrosa is a thin
layer of bone formed over the
surface of the fang of the
tooth by the osteogenetic action
of the periodontal membrane
which invests it. It is made
up of bony lamellae of the
peripheric type, with the char-
acteristic lacunae and canal i-
culi.

The dentine, or ivory, which
forms the bulk of the tooth, is
a connective-tissue structure,
impregnated and hardened by
calcareous salts. It contains
large numbers of minute chan-
nels or passages, the dentinal
tubules, straight or slightly
wavy, with short lateral
branches ; they are parallel to
one another, run perpendicular
to the surface of the dentine,
and open into the pulp-cavity.
Each tubule contains a dentinal
fibre, a process from one of the
odontoblasts or connective-
tissue cells in the pulp- cavity.

Surrounding each tubule is a dentinal sheath, a membranous
portion of the calcified matrix especially resistant to the action

Section of portion of tooth ^Valdeyer).
1, crusta petrosa, showing bony
lacunae and lamellae ; 2, interglobu-
lar spaces— granular layer of Pur-
kinje; 3, dentinal tubules.

DEVELOPMENT OF THE TEETH. 115

of acid. The curves or undulations of the various tubules
correspond to one another, and appear macroscopically as con-
centric lines, the lines of Schreger.

The peripheral portion of the dentine contains numerous
stellate spaces communicating with the tubules, and in the
fang with the canaliculi of the crusta petrosa; these are
called interglobular spaces or dent'mal lacunce, and from its
granular appearance the zone where they occur is called the
granular layer of Purkinje. These lacunae are spaces left by
incomplete calcification, and contain (at least at an early
period) stellate connective-tissue cells.

The incremental lines of Salter are, roughly, concentric lines
formed by interglobular spaces filled with an imperfectly
calcified material ; they indicate successive zones of calcifica-
tion of the dentine.

The pulp-cavity is a space in the interior of the tooth en-
tirely enclosed by the dentine, except at the apices of the
fangs, where the vessels and nerves enter from the dental
canals in the maxillary bones. The pulp consists of delicate
connective tissue intermingled with bloodvessels and nerves.
About the periphery of the pulp-cavity, lining the dentine
which forms its wall, is a layer of modified connective-tissue
cells, called odontoblasts, long columnar or pyramidal cells
lying perpendicular to the dentine and sending processes, the
dentinal fibres, into the dentinal tubules.

Development of the teeth: The enamel is developed from
epithelium, the remainder of the tooth from the subepithelial
connective tissue. Morphologically teeth are usually regarded
as modifications of the papillae of the mucous membrane. At
the beginning of the development of the teeth, the epithelium
of the mucous membrane on the edge of the jaw grows down-
ward into the submucous tissue, dividing into a process for
each tooth. These processes expand below and narrow above,
forming hemispherical epithelial masses, called enamel-organs,
whose connection with the surface-epithelium finally becomes
entirely cut off or reduced to a mere thread of epithelial cells.
Meantime beneath each enamel-organ the connective tissue
becomes vascular and rich in cells, forming a papilla, which
grows upward, pushing its way into and invaginating the
lower surface of the enamel-organ, so that the latter forms a

116 THE ALIMENTARY SYSTEM.

sort of hood over it. The connective-tissue cells at the
periphery of the papilla become modified and arranged in a
layer of odontoblaste, which then produce the dentine.

The enamel-organ consists of epithelium cells at first like
those of the lower or germinal layers of the mucous mem-
brane. The outermost layer of cells of the enamel-organ
become of a columnar or cuboidal type, while the interior
cells degenerate into a pulpy mass of branched cells with
anastomosing processes; the cells (a adamantoblasts ") on the
lower surface of the enamel-organ become especially long and
columnar, and these cells secrete, or become transformed into,
columns of enamel resting on the surface of the dentine.

The crusta petrosa is bony matter subsequently deposited
on the fangs by the osteogenetic action of the periodontal
membrane.

The permanent teeth are formed in a similar manner to the
temporary teeth, their enamel-organs being developed from
buds given off from the epithelial processes which form the
enamel-organs of the temporary teeth.

The Tongue.

General structure : The tongue consists of a mass of volun-
tary muscle, covered with mucous membrane, and contains
small glands, lymphoid tissue, blood and lymphatic vessels,
the terminals of the special sense of taste, and other nerves.

The muscular substance of the tongue is made up of fas-
ciculi of voluntary muscle-fibres interlacing and running in
all directions, supported and bound together by connective
tissue. A vertical fibrous septum divides the tongue into two
lateral halves.

The mucous membrane, which is continuous with that of
the mouth and pharynx, is made up of the usual three layers,
of surface-epithelium, tunica propria, and submucous tissue.

The epithelial covering consists of stratified squamous epithe-
lium, the surface-cells becoming rather horny ; it is very
similar to that lining the mouth and to the Malpighian layer
of the skin. The tunica propria is a firm fibrous membrane
supporting the epithelium and giving strength to the mucous
membrane. The submucosa consists of areolar tissue con-

PAPILLA OF THE TONGUE.

117

tinuous with the connective tissue investing the muscle-fas-
ciculi in the interior. The glands of the tongue are of two
kinds, mucous and serous.

The mucous glands are small racemose glands, occurring in
considerable numbers, and situated in the submucosa and
between the muscular fasciculi.

The serous glands, or glands of Ebner, are small racemose
glands occurring in the vicinity of the circumvallate papillae
and discharging their watery secretion into the furrows sur-
rounding these papillae.

Nodules and masses of lymphoid tissue are abundant, under-

FIG. 48.

FIG. 49.

Papilhe uf human tongue (Heitzmann).

Fig. 48.— Filiform papillae.

Fig. 49.— Fungiform papilla. E, epithelium ; C, tunica propria, showing capillaries ;
L, lymphoid tissue ; .)f, muscle.

neath the epithelium, at the base of the tongue, forming the
so-called lingual tonsil. The tongue is amply supplied with
blood- and lymph vessels and nerves of motion, general sensa-
tion, and special taste-sense.

Papillae of the tongue (Figs. 48, 49, 50) : On the upper sur-

118

THE ALIMENTARY SYSTEM.

face of the tongue the epithelium and tunica propria are thrown
up into papilla?, which are of three or four kinds — filiform,
fungiform, circumvallate, and foliate.

The filiform papilla are most numerous and thickly stud
the upper surface of the tongue. They consist of slender
papillary processes of the tunica propria, surmounted by
slender conical projections of epithelium, the cells of which at
the apex are horny and worn by attrition.

The fwngiform papillce are larger and much less numerous
than the filiform, and are scattered about among the latter as
visible red points. They are lower, broader, and have blunt

FIG. 50.

Circumvallate papillse, of rabbit (Ranvier).
p, fibrous core of papilla ; g, taste-buds ; n, nerves ; a, gland of Ebner.

rounded tops. They consist of a connective-tissue core pro-
jecting from the tunica propria, with minute secondary pro-
jections from its surface, all covered with a layer of epithelium.
The circumvallate papillce are eight to twelve large broad
papillse arranged in a V shape at the base of the tongue. The
papilla? are similar to the fungiform. but are larger, and each
is surrounded by a deep furrow or ditch,, so that the papillse

TASTE-BUDS OF THE TONGUE. 119

themselves do not project much above the surrounding sur-
face, but are depressed.

Scattered about in the epithelial covering of the sides of the
furrow are numerous taste-buds or taste-goblets, oval bodies
made up of modified epithelium and containing the terminals
of the nerves for the special sense of taste.

The serous glands of Ebner open into the bottom of the
furrows, their watery secretions apparently aiding the solu-
tion and dissemination of substances acting on the taste-termi-
nals.

The foliate papillae consist of a few parallel folds of the
mucous membrane on each side of the base of the tongue,
forming alternate ridges and furrows rather than papilla?.
They are better developed in some of the other mammals, as
the rabbit, than in man. The sides of their furrows contain
taste-buds.

The taste-buds are terminals for the special sense of taste,
and occur in the sides of the furrows of the circumvallate
and foliate papillae, with a few scattered about in the epithe-
lial layer of the base of the tongue, the lingual surface of the
epiglottis, and the soft palate. They are oval or egg-shaped
bodies, with the long axis extending through the entire thick-
ness of the epithelial layer, perpendicular or slightly oblique
to the surface. They are made up of two kinds of modified
epithelial cells, the external cortical cells, and the internal
gustatory cells. The outer or cortical cells, also variously
called protective, sustentacular, supporting, and tegmental
cells, are long, slender, flattened, and fusiform cells, each
with a prominent nucleus near its middle.

These cells are arranged longitudinally so as to form an
oval body or covering for the gustatory celte, which lie in the
axis of the taste-bud. The latter are very slender linear
neuro-epithelium cells, with large nuclei near their middle
causing a bulging at that point. They extend the entire
length of the taste-bud, surrounded by the cortical cells.
Their outer ends terminate in fine hairs, reaching the surface
of the mucous membrane through a minute opening or pore
at the apex of the taste-bud ; their inner ends are slender or
branched, and are supposed to communicate with fibres of the
special nerves of taste.

120 THE ALIMENTARY SYSTEM.

The Salivary Glands.

The salivary glands are the parotid, sublingual, and submax-
illary, besides the numerous small mucous glands (labial,
buccal, lingual, and palatal) distributed over the mucous mem-
brane of the mouth and tongue.

General structure : They are racemose glands, consisting of
saccules and ducts supported in sustentacular tissue, divided
into lobes and lobules, and well supplied with bloodvessels,
lymphatics, and nerves.

The sustentacular connective tissue consists of a firm fibrous
capsule enveloping the entire gland, sending in trabeculse
(interlobular septa) which separate the various lobules and
bear the larger vessels and nerves and the interlobular ducts,
and of delicate intralobular tissue penetrating among the indi-
vidual saccules, and forming basement-membranes for their
support.

The ultimate saccules or alveoli, the secreting portions of
the glands, are lined with polyhedral or spheroidal glandular
epithelial cells of the serous or mucous type.

The interlobular ducts are lined with simple columnar
epithelium-cells, which toward their attached bases are marked
with longitudinal stria? or rods.

In the intralobular and intermediate ducts the epithelium-
cells forming the lining become lower and more flattened.

The salivary glands are amply supplied with bloodvessels, a
capillary plexus surrounding the various saccules. The lym-
phatics consist of lymph-spaces between the alveoli, and a
system of vessels. Fine terminal nerve-filaments are supplied
to the secretory-epithelium cells in great abundance, significant
of the well-known great powrer which nervous influences
exert on the secretary action of these glands.

The different salivary glands vary essentially only in the
character of their secretory elements. The parotid is a serous
gland, the sublingual is mucous, the submaxillary mixed.

In the parotid gland the secreting epithelium and alveoli
are of the serous type. The saccules are lined with a single
layer of spheroidal, granular, deeply staining, opaque cells,
with rounded, central nuclei. In the resting stage, when
charged with secretion, the cells are more distended, encroach

SUBLINQUAL GLAND. 121

on and tend to fill the lumen, contain more granules, and stain
less deeply. In the exhausted condition, when the secretion is
discharged, the cells are somewhat contracted and smaller,
leaving the lumen larger, and appear darker, more opaque,
and more deeply stained from the condensation of the proto-
plasm.

In the sublingual gland, which is of the mucous type, the
alveoli are rather larger than in the serous parotid, and have
a prominent basement-membrane. The cells lining the alveoli
are of two kinds, the ordinary mucin-secreting (central) cells
and the peripheral or demilune cells.

Mucous alveoli from submaxillary gland, showing mucinogenous cells and demi-
lunes of Heidenhain (Ranvier).

The former make up much the larger part of the gland and
form a single layer of spheroidal epithelium-cells lining the
lumen, and (except where the demilunes are situated) resting
upon the basement-membrane. These cells are of the type
characteristic of mucous glands ; when resting and distended
with secretion they are swollen, and except where their body-
protoplasm and nuclei are pressed toward the attached bases
the cell-bodies are clear, transparent, and do not stain deeply.
After exhaustion and discharge of the secretion by prolonged
activity, the cells become smaller, less clear and transparent,
and the more concentrated protoplasm stains more deeply.

In places between the mucinogenous or central cells are

122 THE ALIMENTARY SYSTEM.

situated wedge-shaped, pyramidal, or crescentic bodies called
the crescents of Gianuzzi or demilunes of Heidenhain, each of
which is made up of a few opaque granular deeply staining
dark cells. The significance of these demilune cells is quite
unknown, though several views as to their nature have been
propounded, some regarding them as younger germinal cells
destined to develop into mucinogenous cells, others as old and
exhausted cells which have not taken part in the secretory
process, others still as being of the serous type.

The submaxillary gland is mixed, some of its alveoli being
serous, like the parotid, others mucous and with demilunes,
like the subliugual.

The Tonsils.

The tonsils (Fig. 52) are lymphoid glands located between
the pillars of the fauces on each side. They consist of aggre-
gations of lymphoid tissue enveloped by a fibrous capsule
formed by a condensation of the submucous connective tissue.
They are covered by the oral mucous membrane, and rest on
the superior constrictor muscles of the pharynx.

The mucous membrane forming the surface of the tonsil
dips down into a number (ten to fifteen) of blind depressions,
or crypts, or follicles, each of which is lined with a continua-
tion of the stratified squamous epithelium and surrounded by
adenoid tissue.

Mucous glands are present, which discharge into the crypts.
The lymphoid cells infiltrate the tunica propria of the mucosa
so densely as to obscure it ; they even penetrate among the
epithelial cells, often making the boundary between the epithe-
lial layer and the subjacent lymphoid tissue indistinct. The
lymphoid cells make their way entirely through the epithe-
lium in some number, and appear in the mouth as salivary
corpuscles.

The lymphoid tissues in the tonsils, base of the tongue,
palate, and pharynx form an adenoid ring about the fauces and
pharynx. These structures in the tongue and pharynx are
sometimes called the lingual and pharyngeal tonsils.

The saliva as secreted by the salivary glands, is a homo-

THE SALIVA.

123

geneous muco-serous fluid not exhibiting any features to the
microscope ; but as it occurs in the mouth it contains a few
adventitious elements, those derived from the local tissues
being epithelium-cells, leukocytes, and salivary corpuscles;
while bacteria, fungi, food-particles, and other foreign objects

FIG. 52.

Section through crypt of tonsil (Stohr). e, epithelium ; /, lymphoid follicles ; «,
material within the crypt, composed partly of escaped lymphoid cells.

of extraneous origin may be present. The epithelial cells
present are large transparent squamous cells with prominent
nuclei and coarse granules in the body of the cell ; their edges
are often curled. The leukocytes that may be present are
such as have wandered from the bloodvessels. The salivary
corpuscles are lymphoid cells escaped into the mouth from the

124 THE ALIMENTARY SYSTEM,

vicinity of the tonsils ; after exposure to the saliva with its
low specific gravity they become swollen and granular.

The Pharynx.

The walls of the pharynx consist of three layers, mucous
membrane, a fibrous coat, and a muscular layer. The upper
part of the pharynx, above the palate, belongs to the respira-
tory tract and is lined with ciliated epithelium ; the lower
part belongs to the alimentary tract and is lined with squamous
epithelium.

The mucous membrane of the pharynx is continuous with
that of the adjacent cavities, and consists of three layers,
epithelium, tunica propria, and submucosa, and contains
mucous glands and lymphoid tissue.

The epithelial lining in the upper or respiratory portion of
the pharynx consists of stratified ciliated epithelium, con-
tinuous with that of the nasal fossae and Eustachian tubes ;
in the lower or alimentary portion it consists of stratified
squamous cells.

The tunica propria is a well-marked fibrous membrane,
which in the lower part of the pharynx has papillae projecting
among the squamous epithelium.

The submueosa is a layer of areolar tissue connecting the
mucosa with the fibrous and muscular tissues beneath, and
containing numerous small racemose mucous glands and nod-
ules of lymphoid tissue.

The lymphoid nodules often have crypts, like those of the
tonsils. There is a special collection of lymphoid tissue on
the posterior surface of the pharynx between the Eustachian
tubes, called the pharyngeal tonsil.

The fibrous coat, or pharyngeal aponeurosis, is a firm fibrous
membrane lying underneath the mucous membrane, thicker
above, and becoming thinner below. Posteriorly it is thick-
ened to form the median raphe.

The muscular layer, beneath the fibrous, is a sheet of volun-
tary muscle made up by the three constrictors and other
muscles of the pharynx.

The soft palate consists of a thin layer of the voluntary
palate muscles with fibrous aponeu roses, lined on each side by

THE (ESOPHAGUS. 125

mucous membrane like that of the mouth and pharynx, of
whose walls it forms a portion. The epithelial covering con-
sists of squarnous epithelium, except at the upper part of the
posterior surface, where it is ciliated. Mucous glands and
lymphoid tissue are abundant.

The (Esophagus.

The oesophagus is a tube whose walls consist of four coats,
mucous, submucous, muscular, and fibrous, from within out-
ward.

The mucous membrane, which when the oesophagus is col-
lapsed is thrown into longitudinal folds, consists of the epithe-
lial covering, the tunica propria, and the muscularis mucosse.

The epithelium lining the lumen of the tube (Fig. 11) is
composed of stratified squamous cells, flattened on the surface
and gradually becoming thicker and more spheroidal in the
lower layers; it is similar to and continuous with the epithe-
lium of the pharyngeal mucous membrane.

It is underlaid by the tunica propria, a dense fibrous layer
from the surface of which papillae project upward into the
epithelium.

The muscularis mucosce is a thin layer of involuntary
muscle-cells, longitudinally arranged, separating the mucosa
from the submucosa. It is not present in the upper part of
the oesophagus, but appears below in scattered strands, gradu-
ally increases downward, and in the lower part of the tube
forms a well-marked complete ring.

The submucosa, next below, is a layer of loose areolar tissue,
which permits the longitudinal folding of the mucous mem-
brane. It contains small racemose mucous glands, discharg-
ing on the surface, blood and lymphatic vessels, and nerves.

The muscular layer, which lies beneath or outside of the
submucous coat, is composed of two coats, an inner, in which
the muscle-cells are arranged circularly or transversely ; and
an outer, in which they are longitudinal. In the upper portion
of the oesophagus the muscle is striated and voluntary, in the
lower portion non-striated and involuntary ; in the middle it
is mixed and exhibits a gradual transition from one kind to
the other.

126

THE ALIMENTARY SYSTEM.

The outer or fibrous investment of the oesophagus consists
of areolar tissue continuous with that surrounding the adja-
cent structures.

FIG. 53. The Stomach.

The walls of the stomach (Fig.
53) may be divided into four
coats, which are, from within
outward, the mucosa (containing
two kinds of glands, peptic and
pyloric), the submucosa, the
muscular layer, and the serous
or peritoneal covering.

The mucosa consists of the
epithelial covering, subepithelial
connective tissue, muscularis
miicosa?, lymphoid tissue, and
the peptic and pyloric glands.
The epithelial lining of the
stomach consists of a single layer
of long columnar epithelium-
cells, with their nuclei situated
near their attached bases ; among
the columnar cells goblet-cells
are abundant. The surface of
the stomach dips down into
closely crowded tubular depres-
*sions, the gastric glands, which
arc perpendicular to the surface
and occupy the entire thickness
of the mucosa. They are of two
kinds, peptic and pyloric.

The peptic or cardiac glands
occupy the cardiac portion and
fund us of the stomach, yielding
to the pyloric glands' at the
pyloric extremity. The peptic
glands are simple or slightly
divided tubular glands, often
with the lower blind ends some-

Diagrammatic section through coats
of stomach (Mall). TO, mucosa- e
epithelium; d, outlet of peptic
gland; mm, muscularis mucosse;
am, submucosa ; cm, inner circular
muscular layer; lm, outer longi-
tudinal muscular layer- « neri-
toneum.

THE STOMACH.

127

FIG. 54.

what bent and coiled. The ducts of these glands are short,
and lined with a continuation of the surface columnar
epithelium ; the secreting portions of the tubules join the
ducts at the necks of the glands. Besides occasional goblet-
cells, the fundus or secretory part of the peptic glands
is lined with glandular epithelium of two kinds, central or
chief cells, and parietal cells. The
central or chief cells are rather pale,
faintly granular, columnar cells,
which form a complete lining to
the lumen of the glands ; they are
supposed to secrete- pepsin. Be-
tween them and the basement-
membrane, and often causing slight
bulging of tire latter, are scattered
numerous larger oval prominent
cells, the parietal cells, supposed
to be connected with the secretion
of hydrochloric acid ; they do not
form a complete layer, not coming
into contact with one another, and
do not usually abut on the lumen.
Differences in the appearance of
the cells when charged with secre-
tion and when exhausted after di-
gestion occur, analogous to the
similar changes in other serous
glands.

The pyloric glands (Fig. 54) oc-
cupy the pyloric end of the stom-
ach. They are compound tubular
glands, and are similar to the pep-
tic glands, but have longer and
wider ducts and shorter secreting
portions, their lumen is opener
and greater in diameter, they are
more branched (more compound),

and they contain no parietal cells, being lined with central
cells only.

The subepithelial connective tissue of the gastric mucosa, the

Pyloric glands (Bohm and David-
off).

128 THE A LIMENTA R Y S YSTEM.

representative of the tunica propria, is a loose and delicate
connective tissue extending between the glands and providing
basement-membranes and sustentacular tissue for their sup-
port. It contains a rich capillary plexus enveloping the
glands. Lymphoid cells are scattered about and diffuse
lymphoid tissue occurs in places in the subepithelial tissue ;
lymphpid nodules occur especially in the pyloric region, where
they are called lenticular glands.

The mmcularis mucosce consists of two thin layers of in-
voluntary muscle-cells, the outer longitudinal, the inner cir-
cular ; it separates the mucosa from the submucosa, also send-
ing muscular branches up among the gland-tubes. When
the stomach is contracted the mucosa is thrown into folds
or rugaB, permitted by the loose nature of the submucosa.

The submucosa is a loose areolar tissue lying beneath the
mucosa. It contains the larger blood and lymphatic vessels.
The muscular coat of the stomach, lying beneath the sub-
mucosa, is a thick layer of involuntary muscle, divided in
general into two parts, an inner arranged circularly and an
outer longitudinal. At the pyloric orifices the circular muscle
is thickened to form a sphincter.

Outside the muscular layer, and covering the outer surface
of the stomach, is the serous or peritoneal coat, a portion of
the peritoneum reflected over the surface of the organ. It
consists of a thin fibrous membrane covered with endo-
thelium.

The stomach is richly supplied with blood and lymphatic
vessels, the larger trunks lying in the submucous tissue and
giving off capillaries to form a rich network in the mucosa.

The gastric juice consists of a homogeneous serous secretion,
containing leukocytes and epithelium-cells partly digested,
" snail-shell-like " granules probably formed by the action of
the juice on mucin, and extraneous food-particles and
bacteria.

The Small Intestine.

The walls of the small intestine are composed of four layers,
mucous, submucous, muscular, and peritoneal, from within
outward. They are studded with papillary structures called

THE SMALL INTESTINE. 129

villi, and contain two kinds of secretory glands, intestinal and
duodenal, lymphoid structures, bloodvessels, lymphatics, and
nerves.

The mucous membrane is thrown into transverse and
oblique folds, the valvulce conniventes. Its free surface is
raised in papillary projections, called vitti, between the bases
of which the intestinal glands dip down. The mucosa con-

FIG. 55.

f -^--^

««*» rt in • i B ; M

- -

m \ i.&o1

Axial section of villus (Kultschitzky). a, epithelium ; b, gob'.et-cell ; d, C9nnective-
tissue cell of basement-membrane ; e, smooth muscle-cells ; /, reticulum of
tunica propria ; g, central lacteal.

sists of a lining of simple columnar epithelium, which differs
somewhat in the villi and the glands ; subepithelial connec-
tive tissue ; adenoid tissue ; blood and lymph vessels, and
the muscularis mucosse.

The villi (Fig. 55) are minute club-shaped papillaB about a

9— Hist.

130 THE ALIMENTARY SYSTEM.

(millimetre long, which thickly stud the inner surface of the
/entire small intestine. In places they exhibit slight constric-
tions, called Watney's nodes. They are covered with a single
flayer of long columnar epithelial cells (Fig. 13), with their
f nuclei near their attached bases. The protoplasm of the free
ends of these cells contains fine parallel longitudinal striae,
giving the appearance of a narrow striated border. Goblet-
cells are numerous among the columnar cells.

The epithelium-cells rest on a basement-membrane, and the
framework in the interior of the villi is made up by an open
connective-tissue reticulum, the meshes of which contain free
lymphoid cells, forming a diffuse lymphoid tissue. The core
or axis of the villas is formed by a small lacteal, a lymphatic
capillary or radicle ; this is a tube or sac formed by a single
layer of endothelium-cells, with a blunt or slightly expanded
blind extremity above (toward the lumen of the intestine), and
emptying below into the larger lymphatic vessels of the sub-
mucosa. A minute artery enters each villus and breaks up
into a rich capillary network which surrounds the lacteal.
Muscular projections from the muscularis mucosae extend up
into the villi, and apparently serve by periodical contraction
to empty them of their contents. The Junction of the villi is
to absorb the digested food-materials from the intestinal ogcnal
into the blood and lymph circulations. They especially
absorb the insoluble and indiffusible fatty matters, which pass
through the epithelium-cells in small granules, through the
reticulum of the villus, and make their way into the lacteal.

The intestinal glands, or Jollities of Lieberkahn, are straight
simple tubular glands between the bases of thePvilli, ard dip
down to the muscularis mucosse. They, and the surface between
their orifices, are lined with a single layer of short granular
columnar epithelial cells, with nuclei near their bases, which
rest on a basement-membrane. Goblet-cells are interspersed
among these columnar cells. These glands occur throughout
the small and large intestines ; they secrete the intestinal juice
and also perhaps have absorptive functions.

The subepithelial connective tissue of the mucosa, the ana-
logue of the tunica propria, consists of a delicate reticular
tissue, embracing the glands and projecting up to form the
framework of the villi, the surface condensed into a basement-

LYMPHOID GLANDS. 131

membrane. It contains numerous lymphoid cells and diffuse
lymphoid tissue, and is richly supplied with lymphatics and
blood-capillaries. The muscularis mucosce consists of two thin
layers of involuntary muscle, the inner circular, the outer
longitudinal. It lies just below or outside of the extremities
of Lieberkiihn's glands, and separates the mucosa from the
submucosa. It sends fibres up into the villi.

The submucosa of the small intestine is a loose areolar
layer, permitting some play between the mucous and muscular
coats. It contains the larger blood and lymphatic channels,
which send capillaries into the mucosa, and a nerve-plexus, the
plexus of Meissner.

The, duodenal glands, or glands of Brunner, are rounded
compound racemose or perhaps tubular glands, of the s&&wT
type, located in the submucosa of the duodenum. Each
empties by a long outlet-duct which pierces the muscularis
mucosa? and traverses the mucosa to the surface, parallel to the
glands of Lieberkiihn. Their cells are similar to those of the
intestinal glands.

The lymphoid glands of the small intestine are definite and
dense masses of lymphoid tissue, which occur in addition to
the diffuse adenoid tissue of the mucosa ; they are of two
kinds, solitary and agminate. The solitary glands are spherical
nodules or follicles of lymphoid tissue, occurring singly, and
circumscribed by a condensation of the surrounding connective
tissue. They are situated in the submucosa, or may extend
into the mucosa and even to the epithelial covering. They
occur throughout the small and large intestines, but are more
numerous toward the lower part of the ileum and the begin-
ning of the colon.

The agminate glands, or Pgz^ris patches, are aggregations
of a number of solitary lymph-follicles placed in juxtaposi-
tion, and sometimes surrounded by looser adenoid tissue.
They occupy the submucosa, some of the follicles in places
also piercing the muscularis mucosaB and extending into the
mucosa and to the surface-epithelium. They form longitudi-
nal patches two to eight centimetres long opposite the
mesenteric attachment of the intestine, and are most abundant
in the lower portion of the ileum.

The muscular coat of the small intestine comprises two

132 THE ALIMENTARY SYSTEM.

layers of involuntary muscle, a thick inner circular layer, and
a thinner outer longitudinal layer. Between these two is the
nerve-plexus of Auerbach.

The serous or peritoneal coat is the portion of the peri-
toneum reflected over the intestine to form its outer covering.

The intestine is wrell supplied with blood and lymphatic
vessels, the larger channels of which are in the submucosa and
send capillary plexuses into the mucosa. The lacteals con-
stitute an important origin of the lymphatic system.

The intestine is also supplied with two plexuses of nerves ;
the plexus of Auerbach is a network of fibres with minute
ganglia at their intersections, situated between the two layers
of the muscular coat ; the plexus of Meissner, situated in the
submucous coat, is connected with and similar to that of
Auerbach, but is made up of finer fibres and finer meshes.

The Large Intestine.

The large intestine has four coats, mucous, submucous,
muscular, and serous, and contains glands of Lieberkiihn and
solitary glands. It resembles the iletim in structure, but has
no villi or Peyer's patches, and the outer muscular coat is dif-
ferently arranged.

Its mucosa, lined with simple columnar epithelium, is every-
where studded with Lieberkiihn's follicles, supported in a
delicate subepithelial retiform tissue, which is well supplied
with diffuse lymphoid tissue, capillaries, and lymphatics.

The glands of Lieberkuhn are rather larger than in the
small intestine, but are lined with similar cells, among which,
however, goblet-cells are much more abundant.

The muscularis mucosce, vascular and nervous plexuses, sub-
mucous and peritoneal coats are much the same as in the small
intestine, and solitary glands are abundant.

The muscular coat has the usual inner circular layer, rather
thin in most places. The outer layer of longitudinal, non-
striated muscle, however, instead of forming a complete sheet,
is limited to three longitudinal bands, which are shorter than
the other structures, and thus cause the colon to be puckered
or sacculated.

THE LIVER. 133

The appendix vermiformis is similar in structure to the
colon. The raucosa contains well- formed glands of Lieber-
kiihn, and it and the loose submucosa contain numerous lym-
phoid follicles and diifuse lymphoid tissue. The muscular
coat and peritoneal covering form the outer layers.

The rectum has a mucous and submucous layer similar to
that of the large intestine. The covering of simple columnar
epithelium changes at the anus into the stratified squamous
variety.

The internal circular muscular layer is thickened to form
the internal (involuntary) sphincter, over which the longitudinal
muscular layer spreads out to form a complete investment
(instead of consisting of three bands only). The external
sphincter is a thin voluntary muscle surrounding the anus.
The lower portion of the rectum has no peritoneal covering.

The peritoneum is a large serous or lymph sac, formed by a
typical serous membrane covering the walls of the abdomen
(parietal layer) and the abdominal viscera (visceral layer). It
enables the latter to move freely.

It is mainly made up of & fibrous membrane containing lym-
phatics and bloodvessels, lined on the free surface with poly-
gonal endothelium-cells, between which in places are lymph-
stomata.

Beneath it is a variable amount of areolar subserous or sub-
peritoneal tissue, in which, especially in the parietal layers,
mesenteries, and omenta, masses of fatty tissue often accumu-
late.

The blood, lymphatic, and nerve trunks which supply the
intestines are situated in the mesenteries, which also contain
numerous lymphatic glands.

The Liver.

The liver is usually classed as a gland, producing the bile
as a secretion (external). It is much more than this.

All the venous blood from the stomach and intestines, con-
taining the products of digestion absorbed from the alimentary
canal, is collected in the portal vein, redistributed in capillaries
and passed through the liver as through a sieve, and is acted

134

THE ALIMENTARY SYSTEM.

on by intimate contact with the liver-cells before being again
collected in the hepatic vein and discharged into the general
circulation.

In its passage through the liver the constituents of the
blood are, in ways not well understood, altered by the action
of the liver-cells for purposes useful to the animal econ-
omy. This action on the blood, of which the glycogenic
and urea-forming functions are known instances, partakes of
the nature of " internal " secretion. The liver also serves as
a storehouse for certain substances. As a gland the liver is of
the compound tubular type ; but in mammalia it is constructed
more with reference to its functions bearing on the blood, and
its glandular structure is masked and obscure.

General structure : The liver consists of masses of epithelial
cells divided into small lobules or acini, supported in susten-
tacular tissue, and contains a network of outlet bile-ducts and

FIG. 56.

Lobules qf liver of pig, showing interlobular septa and a portal tract (Klein).

three systems of bloodvessels : the hepatic artery, portal vein,
and hepatic vein ; besides scanty lymphatics and nerves.

The sustentacular or connective tissue of the liver consists
of the capsule (of Glisson), interlobular septa, and the " portal
tracts."

The capsule of Glisson is a fibrous envelope investing the
liver, beneath the peritoneum. The interlobular septa

are

THE LIVER. 135

delicate partitions, poorly marked in the normal human liver,
which separate the hepatic lobules. The portal tracts are well-
marked processes of fibrous tissue passing into the liver with
the portal vein, hepatic artery, and bile-ducts, and surround-

FIG. 5'

Diagram of portion of a lobule of the liver (Dunham), a, intralobular vein, receiv-
ing intralobular capillaries ; b, branches of portal vein ; c, branches of hepatic
artery ; d, bile-ducts ; e, lymph-vessel ; /, liver-cells ; g, junction of two lobules.

ing, accompanying, and supporting these vessels in all their
subdivisions and ramifications throughout the organ. These
tracts are situated at the junction of three or four lobules, and
send lamellae between the adjacent lobules continuous with
their interlobular septa, indeed forming the only portions of
these septa conspicuous in the normal liver.

In cross-section the portal tracts are therefore triangular or
stellate, and in each may be seen three or more vessels, the
largest a branch of the portal vein ; and a branch of the hepatic
artery and a bile-duct, which are much smaller. Within the
lobules of the liver connective-tissue elements are very scanty,
being represented only by the endothelium of the capillaries.

136 THE ALIMENTARY SYSTEM.

The hepatic artery is a small vessel, the branches of which
accompany those of the portal vein in the portal tracts. It
supplies blood for the nourishment of the connective tissue
and vessels of the liver.

The bile-ducts collect and convey the bile from the secreting
lobules to the hepatic duct, the general outlet-duct of the liver.
They lie in the portal tracts. The smaller ducts are lined
with simple columnar epithelium (by which they may be dis-
tinguished from the accompanying arteries of corresponding
size), resting on a basement-membrane. As the ducts unite
and become larger the connective tissue by which they are
surrounded forms a thicker layer, in which elastic elements
and involuntary muscle-cells appear.

The portal vein is the main afferent bloodvessel of the
liver, conveying into it the venous blood from the digestive
organs. Its branches follow the portal tracts, and are the
largest and thinnest- walled of the vessels in the latter. As its
branches lie always in the septa between the lobules, they are
called the interlobular veins. They divide into capillaries,
which penetrate and converge to the interior of the lobules,
and there empty into the radicles of the hepatic vein.

The hepatic veins are the efferent bloodvessels of the liver.
They begin by the blind hepatic radicles or intralobular veins,
which lie in the centre or axis of the lobules and receive the
intralobular capillaries. The intralobular veins empty into
larger branches, the sublobular veins, the union of which forms
the hepatic veins.

The lobules or acini of the liver are polyhedral in shape
from mutual pressure, and about a millimetre in diameter.
They are separated from one another by the interlobular septa
of the sustentacular tissue, though in man these septa are
incomplete and the boundaries of individual acini often diffi-
cult to determine. In cirrhosis of the liver and in some mam-
mals the septa are complete and well marked.

Each lobule is made up of liver-cells, intralobular capilla-
ries, bile-passages between the cells, and an intralobular
vein in the centre or axis of the lobule. The acini are built
around the intralobular veins as axes, and their bases abut on
the sublobular veins into which these veins empty.

The liver-cells are polyhedral, nucleated, glandular epithe-

INTRALOBULAR CAPILLARIES.

137

Hum-cells, which often contain granules and fat-particles.
Differences as to granularity, etc., occur in the appearance of
these cells in the various stages of digestion, as between fast-
ing periods and after eating. The liver-cells fill the acini in
a mass interrupted only by the radiating blood- capillaries and

FIG. 58.

Vessels and bile-ducts of hepatic lobule (Cadiat). a, intralobular vein; 6, inter-
lobular veins, breaking up into intralobular capillaries : c, bile-duct with bile-
capillaries (shown only at periphery of lobule).

the bile-passages. They are in contact with one another, and
are not intermingled with connective tissue.

The intralobular veins, the ultimate radicles of the hepatic
veins, occupy the centre or axis of the lobules.

The intralobular capillaries converge toward the intralobular
vein from the periphery of the lobule, where they are formed
by the breaking up of the intfrlobvlor or portal veins; in
section they appear as conspicuous empty spaces or channels

138 THE ALIMENTARY SYSTEM.

between rows of liver-cells, radiating from the intralobular
vein in the centre. They are so arranged that each liver-cell
abuts on at least one capillary. Through these capillaries
the blood passes from the portal vein to the hepatic vein,
coming into close relation with the liver-cells on the way.
The capillaries and the intralobular veins are lined with deli-
cate endothelium-cells which rest on the liver-cells.

The bile-passages are exceedingly fine canals formed by
slight separations or grooves between adjacent liver-cells ;
short lateral blind branches sometimes also enter the bodies
of the cells themselves. These passages unite to form a fine
capillary network, which empties into the bile-ducts in the
interlobular septa. Each bile-capillary is separated from the
blood-capillaries by at least a portion of a liver-cell. These
passages collect the bile secreted by the liver-cells, and though
atypical they are the same in principle as the lumina of
tubular glands. In some animals, as the frog, the tubular
type is more apparent.

The gall-bladder and hepatic, cystic, and common ducts
are lined with mucous membrane, consisting of simple long
columnar epithelium with intermingled goblet-cells, and sub-
epithelial connective tissue, in which mucous glands are
present. In the gall-bladder this coat forms intersecting rugae.

Beneath the mucosa is a fibro-muscular coat, composed of
firm fibrous tissue containing involuntary muscle-cells. Out-
side of this coat, over the greater portion of the surface, is
an external serous or peritoneal covering.

The bile in the gall-bladder is a dark opaque homogeneous
secretion, thick and viscid from the presence of mucin, and is
devoid of formed elements.

The Pancreas.

The pancreas (Fig. 59) is a racemose gland, which secretes
the pancreatic fluid. It is made up of secreting alveoli and
ducts, supported in connective or sustentacular tissue, which
divides it into lobes and lobules, and is supplied with blood-
vessels, lymphatics, and nerves.

The sustentacular or connective tissue consists of an areolar
or fibrous capsule enveloping the gland ; of trabeculse or

SECRETING ALVEOLI. 139

septa (interlobular) of similar tissue which traverse the pan-
creas and divide it into lobes and lobules ; and of delicate
connective tissue penetrating between the individual alveoli
which make up the lobules, and providing them with base-
ment-membranes.

The larger vessels, ducts, and nerves are conveyed through
the organ in the interlobular connective tissue.

The larger (or interlobular) divisions of the ducts are lined

FIG. 59.

Portion of pancreas (Bohm and Davidoff). a, large duct: 6, beginning ducts;
c, d, e, secreting alveoli ; g, sustentacular connective tissue.

with simple columnar epithelium ; the small ductules with flat-
tened epithelium-cells.

The secreting alveoli are rather tubular in form, of the
serous type, and are lined with a single layer of spheroidal
or columnar glandular epitheli urn-cells. The lumen of the
alveoli also sometimes contains small cells, called centro-acinal
cells.

The cells lining the alveoli vary according to the stage of
secretion. Before secretion these cells are distended, and the
zone toward the lumen is clear and contains coarse zymogen-

140 THE ALIMENTARY SYSTEM.

granules, while the protoplasmic zone toward the attached
bases of the cells, where the nuclei are situated, is dark, more
opaque, and less (or more finely) granular. During secretion
the zymogen-granules and clear material distending the cells
are discharged ; when exhausted by prolonged activity the
cells are thus left shrunken, darker, opaque, and non-granular
(or only finely granular).

Bodies of Langerhans : Between the lobules in places are
rounded vascular aggregations of small cells, more open and
less dense than the secreting alveoli which make up the bulk
of the gland ; these are called the bodies of Langerhans, and
are perhaps imperfectly developed lobules, though their nature
is not entirely understood.

CHAPTER XI.
THE RESPIRATORY SYSTEM.

GENERAL CONSIDERATIONS.

The lungs : One function of the lungs, analogous to that of
the alimentary system, is to furnish to the circulation material
(in this case oxygen) required in the nutrition of the body.
Their other function, the excretion of carbon dioxide, is a
glandular process, and in view of it the lungs can be regarded
as a gland ; they certainly approach the glandular type as
closely as does the liver.

The structure of the lungs is strikingly that of racemose
glands ; the main departure from the ordinary glandular type
is that the substances interchanged are gaseous rather than
liquid or solid, and the medium of excretion consists not of
spheroidal cells, but of squamous cells adapted to the ex-
change of gases.

The analogy of the lungs to a gland is increased if their
alimentary or oxygen-furnishing function be regarded as a
sort of internal secretory process, in which the separated
product is discharged into the blood.

The other portions of the respiratory apparatus, the nose,
pharynx, larynx, trachea, and bronchi (the ducts or air-pas-
sages of the lungs), and the pleura, for the most part simply
serve tributary and subordinate purposes to the lungs.

The Nasal Fossae.

The mucous membrane lining the nasal fossae rests upon the
periosteal and perichondrial coverings of the surrounding
bones and the hyaline cartilaginous septum, and is continuous
with the skin and the mucous membrane of the nasal ducts,
pharynx, and Eustachian tubes. It is composed of two dis-
tinct areas, the respiratory and the olfactory. The olfactory
area comprises the upper part of the fossaB, namely, the upper

141

142 TEE RESPIRATORY SYSTEM.

third of the septum, the roof of the nose, the superior and part
of the middle turbinated bone, and the ethmoid in front of
them. The remainder of the nasal fossae and the accessory
sinuses (maxillary, ethmoidal, sphenoidal, frontal) are covered
by the respiratory portion of the mucosa.

The respiratory portion of the nasal mucous membrane, like
the air-passages in general, is lined with stratified ciliated
epithelium, among which are occasional goblet-cells. The
epithelium rests on a firm tunica propria, beneath which is a
variable amount of loose submucous areolar and connective
tissue. The submucosa contains abundant and ample blood-
vessels, nodules and diffuse masses of lymphoid tissue, and
small racemose mucous glands with ducts lined by columnar
epithelium, gradually merging into the ciliated cells of the
surface. The vascularity of this region explains the fre-
quency of nosebleed. Over the septum and turbinated bones
the mucous membrane is thick, very vascular, and contains
large numbers of the glands ; in the accessory sinuses it is
thin and less glandular and vascular.

The olfactory portion of the nasal mucous membrane con-
tains the nerve-terminals for the sense of smell. It is thick,
and mostly pigmented, of a yellowish color. Its superficial
layer is composed of stratified columnar non-ciliated epithe-
lium. The surface-cells are of two kinds, sustentacular and
olfactory.

The sustentacular or supporting cells are long columnar cells,
with deeply placed oval nuclei ; their deep portions are
branched and irregular, their free extremities are granular
and exhibit the appearance of a superficial covering cuticle.

The olfactory cells are slender, elongated, linear cells, with
large spherical nuclei which cause a marked bulbous swelling
of the cell-body. They lie between the supporting cells, and
are a form of neuro-epithelium, or, perhaps, actual nerve-
cells. Their lower extremities are continuous with, or at least
in intimate relation with, terminal filaments of the olfactory
nerve. Their prominent round nuclei form a zone in the
lower portion of the epithelial layer. The lowest epithelium-
cells are spheroidal and germinal.

The epithelium rests upon a connective-tissue layer, the
tunica propria and submucosa, which contain the terminal

THE LARYNX. 143

filaments into which the olfactory nerves divide, and large
numbers of small mucous glands.

The pharynx : The upper portion of the pharynx, which
has been already described (page 124), belongs to the respira-
tory tract, and is lined with ciliated epithelium, while the
lower portion, lined with squamous epithelium, pertains rather
to the alimentary canal.

The Larynx.

The larynx is a cartilaginous box surmounting the trachea
and containing the vocal apparatus.

Its main cartilages, the thyroid, cricoid, and larger portions
of the arytenoids, are of the hyaline variety, tending in old
age to become ossified. The other cartilages, those of the epi-
glottis, certain processes of the arytenoids, the cornicula
laryngis, and cuneiform cartilages (cartilages of Santorini and
Wrisberg), are elastic cartilage.

The ligaments and membranes (thyro-hyoid and crico-
thvroid) which complete the framework of the larynx are
fibro-elastic structures.

The interior of the larynx is lined with mucous membrane,
consisting of an epithelial layer, tunica propria, and sub-
mucous tissue.

The epithelial lining of the larynx above the ventricles and
over the true vocal cords consists of stratified squamous
epithelium, continuous with that of the pharynx ; the ventri-
cles and the portion of the larynx below the vocal cords are
covered with stratified ciliated epithelium, like that of the
trachea.

The tunica propria is a fibrous membrane, containing numer-
ous elastic fibres.

The submucosa consists of areolar tissue, extending down
to the periehondrial coverings, and containing the larger
blood and lymphatic vessels, small racemose mucous glands,
occasional masses of lymphoid tissue, and the intrinsic volun-
tary muscles of the larynx.

The epiglottis contains a basis of elastic cartilage in its
centre, covered on each side by submucous areolar tissue and

144 THE RESPIRATORY SYSTEM.

a mucosa. The mucous membrane on the anterior (or lingual,
or upper) surface of the epiglottis is a continuation of that of
the tongue and is very similar to it.

The vocal cords are folds of the mucous membrane, with
the tunica propria reinforced and strengthened by additional
elastic fibres.

The Trachea.

The trachea is a rigid tube extending from the larynx to
the upper part of the chest, where it divides into the two
bronchi. Its walls are made up, from within outward, of
mucous membrane, submucous tissue, cartilage and muscle,
and fibrous tissue.

The mucous membrane of the trachea is lined with stratified
ciliated epithelium-cells (Fig. 14), among which are occasional
goblet-cells. The tunica propria underlying the epithelium is
a firm supporting connective-tissue layer ; its most superficial
layer forms a basement-membrane for the epithelium ; below
this the tunic is infiltrated with numerous lymphoid cells,
and its deepest portion contains numerous longitudinal elastic
fibres.

Outside the tunica propria is the submucosa, a layer of
areolar and elastic tissue ; it contains the alveoli of numerous
small racemose mucous glands, occasional lymphoid tissue, and
the larger blood and lymphatic vessels.

Next outside the submucosa is a series of incomplete rings
or horseshoe-shaped bodies of hyaline cartilage, defective
posteriorly, which makes up the rigid incollapsible framework
of the trachea. The connective tissue on the surfaces of the
cartilage is condensed to form a perichondrium.

The hiatus at the posterior part of the cartilages is filled up
partially by fibrous tissue, but chiefly by the trachealis muscle,
a bridge of involuntary muscle which connects the ends and
posterior surfaces of the cartilages ; the larger portion of this
muscle is arranged transversely, but externally there are a few
longitudinal fibres.

There are some mucous glands located posterior or external
to the trachealis muscle, whose ducts pierce the muscle and
find their way to the lumen of the trachea.

THE LUNGS. 145

Outside of the cartilaginous layer the trachea is surrounded
by fibrous and areolar tissue continuous with that of the
adjacent structures.

The Lungs.

The lungs are made up of air- vesicles or alveoli, the ulti-
mate functional divisions of the organ ; bronchial tubes, the
air-passages leading to the air-vesicles ; connective sustentacu-
lar tissue ; an ample system of bloodvessels, besides lymph-
atics and nerves; and a serous covering derived from the
pleura.

The lung-substance is more or less distinctly divided into
pyramidal lobules, consisting of the groups of alveoli cor-
responding to terminal divisions of the bronchi and blood-
vessels ; the lobules are to a greater or less extent marked off
from one another by septa, although closely packed together.

The connective tissue of the lung, its sustentacular frame-
work, may be divided into the superficial investment of the
organ and the interalveolar, peribronchial, and interlobular
tissues. The surface of the lung is surrounded by elastic and
areolar tissue, lying beneath the pleura and continuous with
its subserous layer.

The free surface is covered by the visceral portion of the
pleura.

The interalveolar connective tissueis a delicate tissue, mostly
elastic, between, surrounding, and forming a supporting frame-
work for the air-vesicles ; it comprises the larger part of the
pulmonary connective tissue, and to it are due the well-known
elasticity and contractile tendency of the lungs.

The peribronckial connective tissue is a firmer tissue of the
white-fibrous variety which forms definite sustentacular tracts
accompanying, supporting, and surrounding in a single sheath
the bronchi and their concomitant bloodvessels in all their
ramifications and subdivisions throughout the lungs.

The interlobular connective tissue consists of more or less
definite thin fibrous septa separating the lobules of the organ.

Pigment, usually black, is often abundantly deposited in
patches in the interalveolar and interlobular tissue ; it con-
sists of particles inspired into the air- vesicles and removed
into the interior by the lymphatics.

10— Hist.

146

THE RESPIRATORY SYSTEM.

The bloodvessels of the lungs comprise two distinct sets of
arteries, capillaries, and veins : the pulmonary vessels and the
bronchial vessels.

The pulmonary vessels are far the larger of the two sets
and carry out the respiratory function of the lungs. The
pulmonary arteries convey the venous blood from the right
ventricle of the heart, and break up into capillaries which

General appearance of lung under low magnification (Dunham), a, bronchus;
b, muscularis mucosae of bronchus: c, pulmonary veins ; d, e, infundibula.

surround the air-vesicles in a close mesh work. The blood,
aerated and arterialized in these capillaries, is collected from
them and returned in the pulmonary veins to the left auricle.
The pulmonary arteries and veins accompany the bronchi
in their course throughout the lungs, lying in the same
sustentacnlar tract of peribronchial connective tissue, the
bronchus in the centre, a pulmonary artery on one side, and
a pulmonary vein, larger and with thinner walls than the

THE BRONCHI.

147

artery, on the other. The size of the pulmonary vessels
always corresponds to that of the accompanying bronchus,
being not far from equal to it.

The bronchial vessels are much smaller than the pulmonary,
and serve for the nutrition of the substance of the lung.
The bronchial arteries are branches of the aorta. The capil-
laries from these arteries empty chiefly into the bronchial
veins, but partly also into the pulmonary veins. The bron-
chial veins empty ultimately into the vena cava.

The bronchial vessels lie in the peribronchial connective
tissue and accompany the bronchi and pulmonary vessels in
their ramifications.

The lymphatics of the lungs comprise small channels origin-

FIG. 61.

Portion of bronchiole (pig) in cross-section (Schultze). a, submucosa; b, mus-
cularis mucosae ; c, tunica propria ; d, epithelium ; /, portions of neighboring
air-vesicles.

atingfrom stomata in the air- vesicles, in the sustentacular and
perivascular tissue, and from the pleural stomata.

The nerves of the lungs are small branches lying in the
peribronchial tissue.

The bronchi are continuations of the trachea, and within
the lung divide and subdivide dichotomously down to the
terminal bronchioles (Fig. 61). They are the air-passages to

148 THE RESPIRATORY SYSTEM.

the ultimate alveoli of the lungs, and are analogous to the
ducts of glands. They are surrounded by a considerable
amount of firm fibrous connective tissue, the peribronchial
tissue ; each bronchus is accompanied in the same peribron-
chial sheath by correspondingly large pulmonary vessels, the
artery on one side, the vein on the other, and by the smaller
bronchial vessels and nerves, usually a bronchial artery, vein,
and nerve being on each side of the bronchus.

The structure of the bronchi gradually changes as they vary
in size. At the beginning they are about the same in struct-
ure as the trachea.

The medium-sized bronchi are made up, from within out-
ward, of an epithelial layer, a tunica propria, muscularis
mucosse, and a submucosa, which contains plates of cartilage,
mucous glands, and lymphoid tissue, and extends to the peri-
bronchial tissue.

The bronchi are lined with stratified ciliated, epithelium, un-
derlying which is the tunica propria, consisting largely of
elastic tissue. These two layers are thrown into longitudinal
folds.

The muscularis mucosce is a thin but well-marked layer or
ring of involuntary muscle, arranged circularly ; it separates
the tunica propria from the submucosa, and is not included
in the longitudinal folds of the mucosa.

The submucosa consists of areolar tissue, merging into the
firmer peribronchial connective tissue. It contains small
racemose mucous glands, whose ducts discharge on the epithelial
surface; occasional nodules of lymphoid tissue; and unequal
curved plates of hyaline cartilage, the representatives of the
tracheal rings, which in cross-sections appear as arcs incom-
pletely surrounding the bronchi.

Terminal bronchioles : As the bronchi decrease in size the
cartilaginous plates diminish and finally disappear entirely ;
the stratified ciliated epithelium becomes reduced to a single
layer of ciliated cells, and still later to a layer of low columnar
non-ciliated cells; the connective-tissue layers become dimin-
ished in thickness, and the peribronchial tissue and mucous
glands disappear. Thus, the terminal bronchioles are lined
with a single layer of low columnar non-ciliated or flattened
polygonal epithelium-cells, a slight amount of fibro-elastic

THE AIR-VESICLES. 149

connective tissue, and a thinned and interrupted muscularis
mucosse.

The infimdibula : At their termination the bronchioles open
into clusters of large elliptical cavities, called infundibula, the

/
FIG. 62.

Diagram of air-vesicles and termination of bronchi (Miller). B, terminal bronchi-
ole (the line leads from a terminal artery); A, P, alveolar passages; S, infundi-
bulum; C, air-vesicle ; T, beginning vein.

walls of which are beset with air-vesicles. These infundi-
bula branch off from the sides and ends of the final portions
of the bronchioles, which are here somewhat expanded and
lined with flattened polygonal epithelium-cells, and which are
often called alveolar passages.

Each infundibulum is a blind elliptical sac, opening at one
point into an alveolar passage, and with its walls formed
entirely of air-vesicles.

The air-vesicles (air-sacs, air-cells, or alveoli) are small
hemispherical recesses forming the walls of the infundibula
and opening into the cavity of the latter. They make up the
great bulk of the lung-substance, and are the ultimate June-

150 THE RESPIRATORY SYSTEM.

tional divisions of the lungs, where the admission of oxygen
into and the expulsion of carbon dioxide from the blood take
place. They are lined with a single layer of large polygonal
squamous epithelium-cells, at the junction of which appear
occasional small intervals or stomata opening into lymph-
passages. Among the squamous cells lining the vesicles occur
here and there small spheroidal cells ; in the foetal lung, before
it is expanded with air, the cells lining the air-vesicles are all
spheroidal.

Underneath the epithelial lining is a thin network of elastic
tissue (the interalveolar connective tissue), which forms the
framework and support for the vesicles. The walls of the
alveoli also contain a close meshwrork of blood-capillaries
derived from the pulmonary artery, in close relation with the
squamous lining of the vesicles, thus affording favorable con-
ditions for the exchange of gases between the venous blood
and the air in the alveoli. Adjacent air- vesicles are separated
from each other only by thin septa, each of which contains
but a single set of capillaries, the loops of which lie in relation
with the epithelial lining on both sides.

The pleura is a serous sac, the parietal portion of which
lines the thoracic wall, and whose visceral portion forms a
covering for the lung. It facilitates the movements of the
lungs over the opposing surfaces. In structure it is a serous
membrane, consisting of a fibrous stratum covered with poly-
gonal endothelium-cells on the surface. Beneath it is the sub-
serous or subpleural areolar tissue, which in the visceral
portion of the sac is continuous with the superficial connec-
tive tissue of the lung.

CHAPTER XII.

FIG. 63.

THE SKIN.

THE skin serves integumentary and protective purposes, is
an important excretory organ, is the seat of sensory terminals,
and possesses other functions. It consists of two parts, a
thin outer epithelial layer, the epidermis or cuticle, and a
thicker, lower connective-tissue layer, the cutis vera, or corium.
Beneath it is a variable layer of subcutaneous tissue. The
skin contains numerous glands of two kinds, sudoriparous
and sebaceous, and also the hairs and nails; these are all
derived from, or modifications of, the epidermis.

The epidermis, the thinner outer layer of the skin, consists
of stratified squamous epithelium, and is of epiblastic origin.
It varies in thickness and the
development of its parts in
different situations. It is
divisible, in the first place, into
two sharply distinct layers, an
outer, hard, horny, layer, and
a lower, soft protoplasmic
layer, the " rete mucosum."
Each of these is again divisi-
ble into other strata, which
are, from the surface down-
ward, the stratum corneum
and stratum lucidum, making
up the horny portion, the
stratum granulosum and stra-
tum Malpighii, making up the
rete mucosum. In addition,
the lowermost layer of (co-
lumnar") cells in the Mai- Section of skin, showing sweat-gland, a,

,7 stratum corneum; 6, rete mucosum;

pighian Stratum IS almost dlS- c, corium ; d, subcutaneous tissue.

tinct enough to be differen-
tiated as a special layer. These layers may be exhibited thus :

151

152 THE SKIN.

,. . -, f Stratum corneum.

Horny portion of epidermis j Stn!t/um lucidum.

( Stratum granulosum.
Retemaconim | Stratum Malpighii.

Of these layers the strata corneum and Malpighii are the
thickest, most prominent, and always present; the strata
lucidum and granulosum are much thinner, less conspicuous,
and where the epidermis is thin may be quite indistinguish-
able. There are no bloodvessels or capillaries in the epider-
mis, but lymph is probably able to percolate between the cells.

The stratum Malpig-hii (or stratum germinativum) consists
of about ten to twenty-five layers of .deeply staining sphe-
roidal epithelium-cells resting on the corium. Into this
stratum project the papillae which stud the surface of the
corium, the intervals between the papillse being filled with
epithelial cells. The lowermost cells of the Malpighian
stratum form a single layer of tall columnar cells arranged
perpendicular to the surface of the papilla and corium ; this
layer forms a quite distinct stratum. The other cells of the
Malpighian layer, larger than the columnar cells, are spheroi-
dal in shape, or polyhedral from mutual pressure, becoming
somewhat flattened above. They are disposed irregularly, not
in uniform layers, and have characteristic " vesiculated nuclei " ;
that is, their nuclei are surrounded by or seem to lie in a clear
vesicular space. The surfaces of these cells are closely beset
with ridges, or " intercellular bridges," causing the cells to
appear in cross-section as if studded with projecting prickles
or spines, whence they are often called prickle- cells. The
ridges of adjacent cells unite edge to edge, and the minute
communicating channels left between them probably enable
lymph to pass between these cells for the nourishment of the
non-vascular epidermis. The cells of the deeper portion of
the stratum Malpighii contain pigment, which gives color to
the skin, especially in freckles and dark-skinned races. The
Malpighian layer contains terminal nerve-fibrils and tactile
cells.

The stratum granulosum rests upon the stratum Malpighii,
the two merging together without sharp dividing-lines. It is
not always very distinct, but in thick epidermis it appears

SUBCUTANEOUS TISSUE. 153

very prominently as consisting of three or four layers of
flattened, lenticular, or (in cross-section) fusiform cells, which
are dark, stain very deeply, and contain coarse granules of a
substance called eleidin, supposed to be a precursor of the
horny substance of the more superficial cells of the epidermis.

The stratum lucidum is a thin, translucent layer of horny,
flattened cells, lying on the stratum granulosum, and forming
the lowest layer of the horny portion of the epidermis. It
is often indistinct.

The stratum corneum consists of numerous layers of flat,
squamous cells, and forms the thick, outer, horny layer of the
epidermis. The cells consist of a hard, horny substance, or
keratin, into which the protoplasm of the underlying cells has
become converted. There is practically no vitality left in
these cells, but they are well adapted to protective purposes.
In vertical section the cells appear as a succession of wavy
lines, with occasional indistinct traces of the degenerated
nuclei.

The corium, cutis vera, or dennis, is the connective-tissue
portion of the skin, of mesoblastic derivation. It is a firm
fibrous layer, corresponding to the tunica propria of mucous
membranes, and is thicker than the epidermis ; to it the firm-
ness of the skin is due. It consists of an interlacing network
of white and some elastic fibres, among which are scattered
fusiform connective-tissue cells ; mingled with these are numer-
ous capillaries, small lymph-vessels, and nervous elements.

The upper surface of the corium presents numerous oval
papiUce projecting upward into the stratum Malpighii, which
fills the intervals between them. Some of the papillae are
occupied by capillary loops, others by tactile nerve-terminals.
In some situations the papilla? are closely crowded, in others
more sparsely. The arrangement of the papilla? gives rise to
the lines of the palm and sole, and to other superficial mark-
ings elsewhere.

The lower surface of the corium is plane and merges into
the subcutaneous tissue.

The subcutaneous tissue (or superficial fascia) is a layer of
loose areolar and adipose tissue which underlies the corium
and extends to the subjacent structures. It varies in thick-
ness in different parts of the body, and corresponds to the

154 THE SKIN.

submucous layer of mucous membranes. This tissue contains
the larger vascular and nervous branches, and Pacinian cor-
puscles ; the hair-follicles and sweat-glands project down into
it. Next to the corium the subcutaneous tissue is mostly
loose and areolar, while deeper is a variable and often thick
layer of fatty tissue, the pannieulus adiposus.

The sudoriparous or sweat-glands (Fig. 63) occur in great
abundance over the entire skin, and are derived from down-
growths of the epidermic epithelium. They are simple tubu-
lar glands of the serous type, consisting of single tubes lined
by epithelium resting on a basement-membrane, and sup-
ported in the surrounding connective tissue. They extend
from the surface downward into the subcutaneous tissue or
lowest part of the corium, and their deeper portions are much
convoluted. They consist of two parts, a secreting portion
and an outlet-duct. The secreting portion consists of the
lower part of the tube, sometimes somewhat branched, and is
coiled and convoluted into a rounded nodule situated in the
subcutaneous tissue. Its calibre is larger than that of the
outlet portion, and it is lined with a layer of columnar
epithelium. Between the epithelium-cells and their basement-
membrane occur scattered involuntary muscle-cells.

The outlet-duet is a narrow tube of uniform size lined with
two layers of spheroidal epithelium-cells. After leaving the
convoluted secretory portion of the tube it pursues a straight
or slightly wavy course to the epidermis, which it enters be-
tween the papillae. In the stratum Malpighii its lining is
formed by the cells of that layer. Through the stratum
corneum the duct passes to the surface in a spiral or cork-
screw course through the horny substance. The ceruminous
glands of the ear are modified sweat-glands.

The hairs occur in the skin over nearly the entire surface,
being especially numerous and well developed in certain
regions. They are composed of horny cells derived from the
epidermis. The lower end of each hair exhibits a rounded
enlargement, the bulb.

The root of the hairs, the portion imbedded in the skin,
extends into the subcutaneous tissue, and is supported in and
grows from a sheath, the hair-follicle, formed by a downgrowth
of the epidermis and corium.

HAIR-FOLLICLES.

155

A human hair is round or flat-
tened an.i made up of three parts,
a cuticle, a cortex, and a medulla.

The cuticle is a thin outer cov-
ering composed of thin non-
nucleated horny plates or cells,
imbricated or overlapping ; their
edges form irregular transverse
markings on the surface of the
hair.

The cortex,, making up the
bulk of hair, consists of slender,
elongated, fusiform, horny nu-
cleated cells, arranged longi-
tudinally and closely packed and
cemented together.

The medulla is not always
continuous or present ; it con-
sists of nucleated polyhedral cells
loosely aggregated in the axis of
the hair; these cells often con-
tain air, giving them an opaque
appearance.

Hairs often contain pigment,
deposited in the cortex ; to this
pigment and the air in the med-
ulla the color of hair is due.

The hair-follicles (Fig. 64),
which support the hairs and pro-
vide for their growth, are sheaths
formed by downward projections
of the epidermis and corial tis-
sue. They lie perpendicular or
oblique to the surface, and into
their upper half the sebaceous
glands open. A small band of
involuntary muscle extends from
the lower part of the follicle to
the corium across the obtuse-
angled side, forming the erector

FIG. 64.

Longitudinal section of hair-follicle
(Biesiadecki). r. bulb of hair ; d, e,
sheaths derived from the corium ;
/, outer root-sheath ; <7, inner root-
sheath ; h, hair ; k, medulla of hair ;
n, erector pili muscle ; p, papilla of
hair : .*. rete mucosum ; ep, stratum
corneum ; t, sebaceous gland.

156 THE SKIN.

pili muscles, which elevate the hairs and cause projections of the
skin at their bases (cutis anserina). The hair-follicles consist
of two parts — an outer fibrous sheath derived from the coriuni,
and an inner epithelial portion continuous with the epidermis.

The outer fibrous sheath is a supporting investment of fibrous
tissue, longitudinally and circularly arranged, continuous with
the coriuni ; its innermost layer, next to the epidermic sheath,
is a translucent basement-membrane, the hyaline layer. At
the lower end of the follicle the corial tissue sends a cellular
and vascular projection, the papilla, into the hair-bulb.

The inner and more conspicuous epithelial portion of the
hair-follicle is formed by a dipping clown of the epidermis
about the root of the hair. It corresponds mainly to the rete
mucosum, the stratum corneum extending inward only a short
distance near the mouth of the follicle. The epidermic por-
tion of the follicle is usually described as consisting of two
parts, an outer root- sheath and an inner root-sheath.

The outer root-sheath is a continuation of the stratum Mal-
pighii, and consists of several layers of cells similar to those
of that layer in the epidermis. The outermost layer of col-
umnar cells, resting on the hyaline membrane, is very well
marked. Alongside the expansion of the bulb of the hair
the outer or Malpighian sheath becomes thinner. At the
lower portion of the bulb this sheath curves around, upward,
and inward, resting on the papilla, and becomes continuous
with the cells of which the hair is composed, which are thus
formed by gradual transition from the Malpighian cells ; the
innermost cells in this situation, next the papilla, become
cuboidal and merge into the medulla of the hair, while the
outer cells become gradually converted into the elongated
horny cells of the hair-cortex.

The inner root-sheath lies between the hair and outer sheath
along the lower half of the follicle ; above it changes to a
homogeneous sheath which fades gradually away, while be-
low, in the lower part of the bulb, the inner sheath is gradu-
ally lost. It consists of three layers — Henle's layer, Hux-
ley's layer, and the cuticular layer, from without inward.

The layer of Henle is a thin, translucent stratum composed
of a single layer of flattened cells, next to the Malpighian
sheath. Next within is the layer of Huxley, consisting of

THE NAILS. 157

three or four strata of polyhedral cells, which stain deeply
and are perhaps analogous to those of the stratum granu-
losum. The innermost layer is the cuticular layer, composed
of a stratum of overlapping cells lying in close association
with the cuticle of the hair.

The sebaceous glands are oval glandular saccules lying
alongside the upper part of the hair-follicles, into which they
empty. Some are simple or single ; others divided into a few
saccules. Their secretion, the sebum, is of a fatty nature, and
serves to oil and soften the skin and hair. In some situations,
as the labia minora and glans penis, they occur unassociated
with hairs and open directly on the surface. Sebaceous glands
are supported in the surrounding fibrous tissue, have short
outlet-ducts, and are solid masses of cells without open lumina.
The peripheral cells are smaller, spheroidal, and darker col-
ored ; the cells in the centre of the glands are much larger
and clearer, being infiltrated with numerous droplets of fat.
All the cells have well-marked nuclei.

The nails are modifications of the epidermis, consisting
essentially of a much-thickened stratum lucidum. The lay-
ers on which the nail rests and to which it is attached form its
bed. The nail grows only from the posterior or proximal
part of the bed, or the matrix, the pale, visible convex por-
tion of which is the lunula. The posterior edge of the nail,
its root, rests in a groove formed by a fold of rete mucosum.
The corium beneath the nail exhibits the usual fibrous struct-
ure ; its surface anterior to or beyond the matrix forms longi-
tudinal ridges, representing papillae ; over the matrix are
papillae of the ordinary form. On the corium rests a stratum
Malpighii of the usual type, filling the depressions between
the ridges, and overlaid by a stratum granulosum. Upon this
is the body of the nail (corpus unguium), a thick, horny layer
derived from cells which have been transformed into keratin ;
it represents a highly developed stratum lucidum, and is
formed only over the matrix, where continual growth keeps
forcing it onward over the remainder of its bed. There is no
stratum corneum over the nails.

CHAPTER XIII.
THE URINARY ORGANS.

THE action of the urinary organs is excretory, serving to
remove from the blood waste katabolic products and super-
fluous ingested substances. The urinary apparatus consists
of the kidneys, ureters, bladder, and urethra, the latter in the
male being also utilized in the genital function.

The Kidneys.

General structure : The kidneys are compound tubular
glands. They exhibit two parts, the parenchyma or secreting
portion, and the sinus, a cavity containing the calices of the
ureter in which the urine collects and is discharged into the
ureter, which is the outlet-duct of the kidney. The sinus is
situated within the kidney, of which the concave inner mar-
gin constitutes the hilum of the organ, where the ureter, renal
artery, vein, lymphatics, and nerves enter. The renal paren-
chyma is arranged in a radiating manner about the sinus, and
consists of two well-marked zones, an outer or cortex, and an
inner or medulla.

The structural elements of the kidney are the uriniferotis
tubules (beginning with prominent rounded bodies, the Mal-
pighian bodies), bloodvessels, and sustentacular connective
tissue, besides inconspicuous lymphatics and nerves and the
lining of the sinus. The kidneys, being derived from the
foetal Wolffian body, are developed from the mesoblast, thus
forming a notable exception to the usual epiblastic origin of
epithelium.

The medulla of the kidney is composed of a number (eight
to eighteen) of conical bodies, called the pyramids of Mal-
pighi. These radiate about and from the renal sinus, with
their bases outward, resting against the cortex, and their
apices pointing in toward the renal pelvis (of the ureter),

158

MEDULLA OF THE KIDNEY.

159

into the cavities of the subdivisions of which (calices) their
apices project as papillae. The pyramids (or the renal medulla)
have a light- colored, shining, striated appearance, the striae
being radiating or nearly parallel. Two zones in the medulla
are sometimes distinguished, an outer "boundary layer7' and

FIG. 65.

Lobe

Diagrammatic sketch of structure of kidney (Dunham), a, 6, epithelium lining
the calix ; c, column of Berlin ; d, interlobular artery; e, arcuate artery.

an inner " papillary layer." The substance of the pyramids

consists chiefly of straight urinary tubules converging to the

apices ; these produce the striated appearance of the pyramids.

The pyramids are often separated from one another by

160 THE URINARY ORGANS.

walls or processes of the cortical substance dipping down
between them, called the columnar Bertini; in these columns
the bloodvessels pass into the substance of the kidney.

The adult human kidney is not normally divided into
lobes ; but in some mammals and in early human life the
kidney is lobed, each Malpighian pyramid with the adjacent
cortical substance forming a distinct lobe separated from other
lobes by clefts in the renal substance.

The cortex of the kidney is a dark-red granular zone, much
narrower than the medullary region, and forming the periph-
ery, just underneath the capsule. It also sends processes
down between the Malpighian pyramids, the columnar Bertini
mentioned above. The substance of the cortex is divided
into the pyramids of Ferrein and the interpyramidal regions,
which alternate with one another.

The pyramids of Ferrein, or medullary rays, or cortical
pyramids, are narrow bundles or sheaves of straight tubules
which radiate from the outer boundary of the Malpighian
pyramids through the cortex nearly to the periphery. These
cortical pyramids consist of straight portions of the uriuifer-
ous tubules, which are continuations of the radiating tubules
of the Malpighian pyramids, each of the latter giving off a
number of pyramids of Ferrein from its base. The tubules
in the centre are longer than those on the outside of each
pyramid of Ferrein, giving it the shape of a cone with a
narrow base.

The intervals between the cortical pyramids are occupied
by the interpyramidal substance (or labyrinth) of the cortex.
This consists of the coiled and irregular portions of the
uriniferous tubules, twisting in all directions, studded and
intermingled with the numerous prominent round Malpighian
bodies, which give the cortex its granular character.

The interpyramidal cortical regions comprise the active
secretory parts of the kidney; the pyramids of Ferrein and
Malpighi simply contain conducting tubules.

The sustentacular connective tissue of the kidney consists
of the capsule, the intertubular or interstitial tissue, the peri-
vascular tissue, and the connective tissue lining the wall of
the renal sinus and continuous with the pelvis (ureter).

The capsule is a firm fibrous membrane enveloping the

SUSTENTACULAR CONNECTIVE TISSUE.

161

gland ; it is connected with the delicate intertubular tissue
of the interior ; but as it does not send any firm trabeculae

FIG. 66.

Diagrammatic representation of uriniferous tubules (Klein). A, cortex of kidney;
B, boundary zone, and C, papillary portion of Malpighian pyramid ; a, subcap-
sular portion, and a', inner portion of cortex destitute of Malpighian bodies;
], Malpighian body, capsule of Bowman, and glomerulus; 2, neck ; 3, proximal
convoluted tubule; 4, spiral tubule; 5, descending limb of Henle's loop;
6, Henle's loop; 7, 8, 9, ascending limb of Henle's loop; 10, irregular tubule;
11, distal convoluted tubule; 12, curved tubule; 13, 14, collecting tubule.

11 — Hist.

162 THE URINARY ORGANS.

into the gland it can normally be easily stripped off from the
surface.

The connective tissue permeating the renal parenchyma
(the intertubular or interstitial tissue) is a delicate tissue, very
small in quantity, penetrating between and supporting the
uriniferous tubules and vascular channels ; it consists chiefly
of the basement-membranes on which the tubules rest. Some
connective tissue also accompanies the vessels entering at the
hilurn, and in and beneath the lining of the renal sinus are
considerable quantities of fibrous, areolar, and adipose tissue.

The uriniferous tubules (Fig. 66) are the secreting or gland-
ular elements of the kidney. They consist of long tubes,
which (except the larger collecting- ducts) are single and un-
branched. They are lined with a single layer of epithelium-
cells resting on a basement-membrane, and in different parts
of their course exhibit different divisions varying in arrange-
ment, form, and structure. The parts into which the tubules
are divided are, in their order, as follows : Malpighian body ;
neck ; proximal or first convoluted tubule ; spiral tubule ;
the loop of Henle (consisting of a descending limb and ascend-
ing limb) ; irregular tubule ; distal or second convoluted
tubule ; curved or arched tubule ; straight collecting tubule,
and tube of Bellini.

The Malpighian body is a hollow spherical structure or ex-
panded sac forming the beginning of each uriniferous tubule.
Its wall is formed by a membrane called the capsule of Bow-
man, and into its cavity, but covered by its epithelium, pro-
jects a tuft of capillary bloodvessels called the glomerulus.

The capsule of Bowman consists of a single layer of squam-
ous epithelium resting on a basement-membrane. It forms a
hollow spherical sac, the cavity of which at one point opens
into the proximal convoluted tubule through a small neck.
The layer of squamous epithelium is invaginated into the
cavity so as to form a complete covering for the glomerulus
(Fig. 67).

The glomerulus is a tuft of capillaries coiled into a spherical
mass nearly filling the interior of the Malpighian body.

The capillaries arise from a single afferent vessel, and unite
to form a single slightly smaller efferent vessel; these two ves-
sels enter and leave the glomerulus together, forming a sort

MALPIGHIAN BODIES.

163

of stalk for the tuft, at a point opposite the neck or junction
of the body with the uriniferous tubule.

The surface of the glomerulus is covered with a layer of
squamous epithelium ("tuft-cells")? dipping down into the
depressions between the capillary-loops ; this epithelium is a

FIG. 67.

Sketch of Malpighian body (Dunham), a, interlobular artery; 6, afferent vessel:
c, capillary ; d, capsule of Bowman ; e, cavity of the capsule ; /, beginning of
proximal convoluted tubule ; g, portions of convoluted tubules.

reflection of that lining the capsule of Bowman, with which
it is continuous at the stalk of the glomerulus.

Thus the glomerulus is "outside" the capsule of Bow-
man just as the heart is outside the cavity of the pericardium.

Malpighian bodies — arrangement and function: The Mai-

164 THE URINARY ORGANS.

pighian bodies are all situated in the interpyraraidal portions
of the cortex, which they stud as prominent granular points.
The arrangement of the Malpighian body is adapted to
secretory action ; the expanded glomerulus affords a large
surface over which fluid may transude from the blood cir-
culating in the capillaries into the cavity of the capsule and
uriniferous tubule. The slightly smaller size of the efferent
vessel is explainable on the ground that the blood entering
by the afferent vessel loses a portion of its fluid through the
walls of the glomerulus.

The neck of the uriniferous tubule is a constricted portion
at the junction of the Malpighian body with the proximal
convoluted tubule. At this point the squamous cells of the
capsule of Bowman become thicker and merge into the
cuboidal cells that line the convoluted tubule.

The proximal convoluted tubule, the first portion of the
uriniferous tube, is much twisted, contorted, and bent. It is
lined with a single layer of columnar or spheroidal epithe-
lium-cells, which are striated toward their attached bases ;
these cells are opaque, granular, somewhat irregular in shape
and unequal in size, and of glandular type. The proximal
convoluted tubules have a greater calibre than most portions
of the uriniferous tubules; they are situated in the inter-
pyramidal portions of the cortex, are surrounded by abundant
capillaries, and are active secretory portions of the tubules.

The spiral tubule is the term applied to the portion of the
uriniferous tubule that succeeds the proximal convoluted por-
tion. It is straighter than the latter, having only a slight
spiral twist, and lies in a pyramid of Ferrein, passing down to
the medulla. It is lined with simple columnar epithelium
resembling that of the convoluted tubule, but rather lower
and less striated.

The descending limb of Henle's loop begins at the junction
of the cortex and medulla, where the spiral tubule merges
into it, and lies in a Malpighian pyramid, passing downward
to the loop of Henle. At the latter point the uriniferous
tubule makes a sharp U-shaped bend on itself, turning upward
in an ascending limb.

The descending limb is a straight, narrow tube lined with
a single layer of flattened or lenticular epithelial cells, the

BLOODVESSELS OF THE KIDNEY. 165

nuclei of which cause a slight bulging at the centre of the
cells. As the nuclei and bulging portions of the cells alter-
nate on opposite sides of this tubule its lumen appears slightly
sinuous.

The ascending limb of Henle's loop is situated partly in the
Malpighian pyramid and partly in the pyramid of Ferrein.
It is straight, parallel with the descending limb, and is lined
with a single layer of columnar epithelium.

The irregular tubule is the portion of the uriniferous tubule
succeeding the ascending limb, and is situated in the inter-
pyramidal cortical substance. It pursues an irregular angular
course, and is lined with striated, simple columnar epithelium.

The distal convoluted tubule succeeds the irregular portion,
is situated in the interpyramidal cortex, and is similar in all
respects to the proximal convoluted portion of the uriniferous
tubule.

The curved or arched tubule is a short, curved tube, in which
the distal convoluted tubule terminates. It passes into a
pyramid of Ferrein and empties into one of the straight col-
lecting tubules. It is lined with low cuboidal epithelium
resembling that of the straight tubes.

The straight collecting tubes begin in the pyramids of Fer-
rein and pass in straight lines through the medulla of the
kidney to the apices of the Malpighian pyramids, where, hav-
ing successively united into a smaller number of ducts, of
larger size, they empty into the calices as above stated.
These largest discharging ducts are called the tubes of Bellini.
Into each collecting tube opens, in the pyramids of Fer-
rein, a number of the curved tubules by which the secretory
portions of the uriniferous tubules are connected with the col-
lecting tubes.

In this manner the urine secreted by the secretory tubules
is collected and discharged into the pelvis of the kidney.

The collecting tubes have large open lumina, and are lined
with a single layer of clear columnar epithelium cells, which
are shorter in the cortical portion of the kidney and become
longer in the papillary region and tubes of Bellini.

The bloodvessels of the kidney (Fig. 68) are branches of
the renal artery and vein. These vessels enter the kidney
at its hilum and pass into the areolar tissue within and lin-

166

THE URINARY ORGANS.

FIG. 68.

Course of bloodvessels in the
kidney (Ludwig). a, inter-
lobular artery; b, inter-
lobularvein;c, Malpighian
body, with afferent and
efferent vessels and glom-
erulus; d. stellate vein;
e, arterise rectrc ; f, venae
rectae ; g, capillaries about
mouths of outlet-ducts.

ing the sinus. They give off twigs
which supply this region and divide
into a number of branches, the arterice
and venae proprice renales, which pass
outward in the columnse Bertini, be-
tween the Malpighian pyramids.

On reaching the bases of these pyra-
mids they divide into the arcuate ar-
teries and veins, which follow the
boundary between the cortical and
medullary regions and, anastomosing
with one another, form complete ar-
terial and venous arches over the bases
of the Malpighian pyramids. From
these arches two sets of small vessels
are given off, one the interlobular, pass-
ing radially outward into the cortex ;
the other, the vasa recta, converging
inward to supply the medulla.

The interlobular arteries,1 or cortical
arteries, are small straight branches
from the arterial arches passing radially
outward in the interpyramidal cortical
regions, midway between the pyramids
of Ferrein. They give off a small
twig to each of the Malpighian bodies
along their course, which enters the
glomerulus as its afferent vessel. In
the glomerulus the afferent vessel
breaks up into a capillary tuft; the
capillaries then reunite to form a single
efferent vessel leaving the glomerulus.
These efferent vessels then mostly

1 Each pyramid of Ferrein, with the tributary
interpyramidal tubules in its vicinity, may be
regarded as a distinct section or physiological
lobule of the renal cortex, though they are not
marked off' from one another by definite bound-
aries into distinct lobules. The cortical arteries
pass between these sections or lobules, whence
the term interlobular.

SECRETION OF THE URINE. 167

break up into another capillary network enveloping the uri-
niferous tubules in the pyramids and interpyramidal regions
of the cortex. These capillaries then unite again and empty
into the interlobular veins, which occupy a situation corre-
sponding to that of the interlobular arteries, and empty into
the venous arches. The capillaries beneath the capsule unite
in venous branches, the stellate veins, which meet in a star-
shaped manner and empty into the interlobular veins.

The arteriae rectas are small straight arterioles which arise
in large numbers from the concave sides of the arterial arches
and pass into the Malpighian pyramids, converging to the
apices of the latter. They divide into elongated capillary
meshes embracing the uriniferous tubules of the medulla.
A few arteriolae recta? are also derived from afferent vessels
of some of the glomeruli, which pass into the medulla, instead
of breaking up into capillaries in the cortex. The blood from
the medullary capillaries is collected by the vence rectce, which
are arranged similarly to the arteriae recta? and empty into
the venous arches.

The structures composing the different parts of the kidney
may be recapitulated as follows : the interpyramidal portions
of the cortex contain the Malpighian bodies, the proximal
and distal convoluted tubules, the irregular tubules, the curved
tubules, and the interlobular vessels.

The pyramids of Ferrein contain the spiral tubules, part of
the ascending limbs of Henle's loops, and portions of the
straight collecting tubes.

The medulla contains the descending and part of the
ascending limbs of Henle's loops, part of the straight collect-
ing tubes, the tubes of Bellini, and the vasa recta.

The secretion of the urine is accomplished somewhat as fol-
lows : In the Malpighian bodies fluid transudes or filters from
the blood through the thin capillary- walls and squamous cells
into the cavity of the capsule of Bowman. The fluid thus
separated is supposed to be mainly water, with very little
solids. The glandular epithelium of other portions of the
tubules, the convoluted tubules especially, then remove from
the blood in the surrounding capillaries the solid constituents
of the urine by a true secretory process ; these solids are dis-
solved by the fluid passing down the tubules.

168 THE URINARY ORGANS.

The pelvis of the kidney, centrally situated at one side, is
continuous with or forms the upper extremity of the ureter.

This expanded upper end of the ureter divides into two or
three divisions or infundibula, and these into calices into
which the apices of the Malpighian pyramids project as
papillce.

The wall of the renal pelvis consists of three layers, mucous
(composed of epithelium and a tunica propria), muscular, and
fibrous or areolar. The superficial layer of the mucosa con-
sists of stratified squamous epithelium, of the variety called
transitional, made up of a few layers of cells rapidly changing
from the deeper spheroidal to the superficial squamous form.
The epithelium rests on a fibrous tunica propria, beneath which
is a fibro-muscular layer, containing involuntary muscle-cells.
Underneath the latter is a broad layer of fibrous tissue.
Within the renal sinus is a variable amount of areolar tissue,
extending to the kidney-parenchyma, and usually containing
considerable masses of adipose tissue. In this areolar tissue
the larger arteries and veins of the kidney are situated and
subdivide. The mucosa is said to contain a few small race-
mose glands, though the presence of such glands in the urinary
tract is disputed.

The ureter is continuous with the renal pelvis, and its walls
consist of three coats, mucous, muscular, and fibrous.

The mucous coat, which in the contracted ureter is thrown
into longitudinal folds, consists of a lining of transitional
epithelium, resting on a fibrous layer which represents a
tunica propria and submucous layer. The mucosa is said to
contain a few small racemose mucous glands.

Outside the mucosa is the muscular coat, composed of in-
voluntary muscle in three layers, an inner longitudinal, a mid-
dle circular, and in the lower portion of the ureter a thin
outer longitudinal layer. Surrounding the muscular coat is
an areolar or fibrous layer.

The Bladder.

The walls of the bladder consist of three coats — mucous,
muscular, and fibrous, from within outward.

The mucous coat, which is thrown into folds when the organ

THE URETHRA. 169

is contracted, consists of an epithelial layer, tunica propria, and
submucosa.

The epithelium lining the bladder consists of a few layers of
stratified squamous or transitional epithelium (Fig. 12), con-
tinuous with and similar to that lining the ureters and renal
pelvis. The superficial layer of cells in the epithelium is a
stratum of thick, squamous, or lenticular cells, possessing
sometimes more than one nucleus each ; the lower surfaces of
these cells exhibit indentations into which the underlying cells
project. The cells beneath this outermost layer are oval or
pyriform and perpendicular to the surface ; the two or three
layers beneath these are spheroidal or irregular germinal epi-
thelial cells.

The epithelium rests on a firm fibrous tunica propria ; be-
neath this is a layer of loose or areolar submucous tissue con-
tinuous with the fibrous tissue permeating the muscular coat.
A few small racemose mucous glands are said to be present in
the mucosa of the base of the bladder.

Outside the submucosa is the thick muscular layer, composed
of fasciculi of involuntary muscle supported in fibrous tissue.
The arrangement of the muscular fasciculi is rather indefinite,
but in general three layers can perhaps be distinguished : an
inner longitudinal layer ; a middle circular layer, thickened
at the neck of the bladder to form the sphincter vesicse ; and
an outer longitudinal layer.

Outside of the muscular coat is a fibrous layer, of areolar
tissue, which over a large portion of the fundus of the bladder
is covered by peritoneum.

The Urethra.

The female urethra is lined internally with epithelium, strati-
fied squamous, or sometimes, it is said, simple columnar. The
epithelium rests on a firm tunica propria, which, especially
toward the meatus, has papillae projecting into the epithelium.
Beneath the tunica propria is a loose submucosa, which con-
tains expanded venous sinuses forming an erectile tissue.
Small racemose mucous glands (urethral or Littre's glands)
also occur in the submucosa, most numerous at the meatus.
The mucosa, consisting of the above-mentioned layers, lies in

170 THE URINARY ORGANS.

longitudinal folds. Outside the submucous tissue is a well-
marked non-striated muscular coat, having an inner longitudi-
nal and outer circular layer, and intermingled with elastic
tissue. Outside the muscular coat is fibrous tissue, in which
the urethra is imbedded.

The male urethra : The walls of the male urethra are com-
posed of epithelium resting on a tunica propria (forming a
mucous coat), submucous tissue, and muscular tissue, and con-
tain numerous mucous glands.

The epithelium lining the male urethra is of the transitional
variety at the vesical end, then changes to stratified columnar ;
throughout the middle and longest portion (penile) it is sim-
ple columnar, and for a short distance back of the meatus is
of the stratified squamous type.

The epithelial layer rests on a fibrous tunica propria which
toward the meatus sends papillae into the epithelium.

These layers form the mucosa, which in the flaccid condition
of the canal lies in longitudinal folds.

Outside the tunica propria is the submucous layer of areolar
and loose fibrous tissue.

In the penile portion of the urethra the submucous tissue
merges into the cavernous or erectile tissue of the corpus
spongiosum, which is enveloped in a strong fibrous sheath.

The submucosa along the entire course of the male urethra
contains small racemose mucous glands, the urethral glands or
glands of Littre, lined with columnar epithelium and opening
into the urethral canal ; in the penile portion these glands are
scattered throughout the erectile tissue.

The muscular coat of the urethra lies outside or within the
submucous coat. In the prostatic and membranous portions
the muscular layer lies beneath the submucosa, and consists of
inner longitudinal and outer circular fasciculi of non-striated
muscle.

Outside these muscular layers in the membranous urethra
is an additional muscle, the voluntary compressor urethrse.

In the penile portion of the urethra the muscular layer is
imbedded in the submucous tissue. Near the bulb the inner
longitudinal and outer circular layers of smooth muscle are
still present ; but anteriorly the circular layer disappears and
the longitudinal fasciculi become thinned and scattered.

URJNE. 171

The urethra is surrounded in its prostatic portion by the
prostate ; in its penile portion by the corpus spongiosum ; be-
tween these two portions is a short interval, the membranous
portion, in which the urethra is supported in fibrous tissue.

The urine is a clear, homogeneous, serous secretion, contain-
ing a slight amount of mucus. A very few adventitious ele-
ments may be normally present — detached epithelium-cells,
mucous corpuscles, stray leukocytes, and spermatozoa. In
abnormal conditions a variety of organic formed elements and
crystalline or amorphous solid substances may appear.

CHAPTER XIV.

THE REPRODUCTIVE SYSTEM.

THE consideration of the organs of reproduction naturally
falls into two parts, those of the male and those of the female.

MALE GENITAL ORGANS.

The male genital organs consist of the testicles, the epidid-
ymis, the vas deferens, the seminal vesicles, the prostate,
Cowper's glands, and the penis, besides vestiges of foatal
structures. The main portion of these, the testes and seminal
ducts, are derived from the embryonic Wolffian body, and
their epithelium is therefore of mesoblastic origin.

The scrotum, the pouch containing the testicles, is covered
externally with skin, thin and plicated. Beneath, and closely
connected with the skin, is the dartos, a layer of vascular
contractile tissue composed of areolar tissue and involuntary
muscle. A septum from the dartos divides the scrotum into
lateral halves. Beneath the dartos are strata of areolar and
fibrous tissue — the intercolumnar fascia, cremasteric fascia, and
fascia propria ; the cremasteric fascia also contains strands of
striated and non-striated muscle. Beneath these layers is the
parietal layer of the tunica vaginalis, a closed serous sac
derived from the peritoneum and invaginated into itself to
form a covering for the testicle.

The Testicle.

The testicle is a compound tubular gland in which the
spermatozoa are generated. Attached to the posterior aspect
of the testicle is the epididymis, which consists of a body, an
expanded upper extremity, or head, called the globus major,
and a smaller lower extremity, or tail, the globus minor.
The testicle is essentially a congeries of tubules, secretory
172

SEMINIFEROUS TUBULES. 173

and conducting, called the seminiferous tubules, supported in
a connective-tissue framework. It is well supplied with
bloodvessels, and also has lymph-channels; its nerve-supply is
inconspicuous and obscure.

The surface of the testis is covered with a serous membrane,
the visceral layer of the tunica vaginalis ; this sac is invagi-
nated over the testis from behind, leaving a hiatus or hilum
for the entrance of the elements of the spermatic cord.

The sustentacular connective tissue of the testis consists of
the tunica albuginea, mediastinum testis, and interlobular and
intertubular tissue.

The tunica albuginea is a dense fibrous capsule enveloping
the organ, lying underneath and merging into the visceral
layer of the tunica vaginalis. At the posterior part of the
testis the tunica albuginea is thickened, forming a longitudinal
ridge or mass called the mediastinum testis, or corpus of High-
more; this contains a system of communicating spaces, the
rete testis.

In infancy numerous well-marked fibrous partitions (inter-
lobular septa) radiate from the mediastinum testis and, extend-
ing across toward the tunica albuginea opposite, divide the
testicle into a number of conical compartments or lobules,
with their apices directed toward the mediastinum.

The adult and fully developed testicle, however, is often
less completely and less conspicuously divided into lobules,
the interlobular septa being occasional rather indefinite fibrous
laminae, a little thicker than the intertubular septa.

Lining the interlobular septa and the inner surface of the
tunica albuginea is the tunica vasculosa, a layer of areolar
tissue containing abundant bloodvessels.

The individual seminiferous tubules are separated from one
another by the intertubular tissue, thin connective tissue parti-
tions containing capillaries and providing basement-membranes
for the tubules. In places within the intertubular tissue are
situated groups of large spheroidal epithelioid (?) cells, inter-
stitial cells.

The seminiferous tubules exhibit several divisions, which are,
from their beginning onward, as follows : convoluted tubules,
tubuli recti, rete testis, vasa efferentia, and epididymis. The
convoluted portions generate the spermatozoa, the remaining

174 THE REPRODUCTIVE SYSTEM.

seminal ducts are conducting-channels or secrete fluid constit-
uents of the semen.

The convoluted tubules are single or branched tubes, of
large diameter, coiled, bent, and twisted in intricate convolu-
tions, closely packed together so as to fill practically the entire
testicles. They are surrounded by well-marked basement-
membranes, and their coils are separated from one another by
the thin intertubular connective tissue. The tubules are lined
by several layers of epithelium, from which the spermatozoa
are generated.

The deepest or parietal layer of epithelium consists of large
spheroidal spermatogenic cells (" spermatogonia ") resting on
the basement-membrane, among which are occasional long
sustentacular cells (" cells " or "columns of Sertoli") projecting
inward among the other cells toward the lumen.

Upon these parietal cells rests a layer or two of large
spheroidal cells, mother-cells, derived from the " spermato-
gonia." Next internal to these are a greater number of
smaller spherical-cells ; these are called daughter-cells (also
called " spermatids " and " spermatoblasts "), and are derived
from the mother-cells.

The daughter-cells elongate and develop into the sperma-
tozoa, (described below), which are located in clusters, their
heads (until they become separated) being attached to the
daughter-cells and their tails projecting into the lumen. The
lumen of the tubules contains, besides the spermatozoa, a
broken-down granular material.

Spermatogenesis : The development of the successive layers
and generations of spermatogenic cells and the spermatozoa
takes place by karyokinesis.

All parts of the seminiferous tract are not simultaneously
engaged in active cell-division, but the different stages of the
process are observable in different regions at the same time.
While karyokinesis and the production of spermatozoa are
actively going on in some places, in others the cells are
quiescent and spermatozoa absent. Some of the details of
the process of generation of the spermatozoa are still undeter-
mined or in dispute. It is supposed that during their
generation the number of chromosomes of the spermatozoa

TUUULE RECTI OR STRAIGHT TUBULES. 175

becomes " reduced " to half the number characteristic of the
cells of the species (page 36), so that when joined to the
female element, likewise reduced (page 39), the fertilized
ovum possesses the normal number of chromosomes (sixteen
in man).

As the spermatozoa are endowed with the power of transmitting to
the offspring the characteristics of the parent, the process of spermato-
genesis is a link in the chain of heredity. The mode by which the
parent implants or involves his own characteristics within the minute
compass of a spermatozoon, so that the latter in its further develop-
ment reproduces its kind, is a biological question of great importance.

The characters of the parent are either congenital (racial, inherited)
or acquired; the latter few in number, the former multitudinous.
Many biologists contend that characteristics acquired by an individual
subsequent to his conception and birth cannot be transmitted to his
offspring; but supposing it possible, what mechanism exists in the
genital organs by which the features of a distant part of the body can
be impressed upon spermatozoa developing in the testicle so as to be
carried on to the progeny ? Obviously the only channels by which
impressions or influences from other parts could be conveyed to the
testicle are the circulation and the nerves. The testes are amply sup-
plied with bloodvessels; not so well, perhaps, with nerves. We can
conceive how, in conditions of toxaemia or generally lowered vitality,
an impoverished or toxic blood could alter or lower the vitality of the
spermatogenic cells and thus convey a deteriorating tendency to the
offspring; and we are also familiar with trophic nervous effects; but
aside from these, the manner in which bodily features might become
impressed on the spermatogenic cells through nervous or circulatory
influences is obscure.

Little is known likewise as to just how the congenital or inherited
features of the parent, the fixed and stable characters of the race, are
carried over from generation to generation. Amidst the vast multi-
tude and diversity of cells making up the body, what line of cellular
transmission of racial features connects the 'ovum, from which an
organism develops, with the ovules or spermatozoa of the next genera-
tion which after a time appear in the body of the parent ?

Many biologists regard the cells into which an ovum develops as of
two fundamentally different kinds : somatic cells, making up the body
generally ; and germ-cells, to which the developmental powers of the
ovum are transmitted. According to this theory, the spermatogenic
cells of the testicle and the corresponding cells of the ovary are direct
descendants of the ovum through a succession of germ-cells (located
in the sexual glands), which have carried on, in isolated continuity as
it were, the reproductive potentialities inherent in the ovum.

The tubuli recti or straight tubules: The convoluted tubules
converge toward the mediastinum testis, and at their proximal

176 THE REPRODUCTIVE SYSTEM.

ends terminate in short straight tubules which empty into the
channels forming the rete testis. These tubuli recti are nar-
rower in calibre than the convoluted portions, and are lined
with a single layer of low columnar or cuboidal epithelium-
cells.

The rete testis is a network of anastomosing channels and
sinuses formed by the union of the tubuli recti. These chan-
nels are situated in the substance of the mediastinum testis,
and are lined with a single layer of flattened epithelial cells
resting on the surrounding fibrous tissue.

The vasa efferentia : The seminiferous channels of the rete
testis at its upper end continue upward in the form of ten to
fifteen efferent vessels, the outlet-ducts of the testis, which
pass through the tunica albuginea and enter the globus major,
where they form the coni vasculosi. These vasa efferentia are
lined with stratified columnar epithelium, partly ciliated • the
epithelium cells are thrown up into ridges and papilla? which
project into the interior of the tubules and give the free
surface a sinuous and undulating character. The epithelium
rests on a basement-membrane and thick fibrous A
taining involuntary muscle-cells arranged transversely.

In the globus major the efferent tubules are coiled and con-
volu£ed, making up the coni vasculosi (or lobuli epididymidis\
each tube forming a conical mass or lobule. The globus major
is made up of these lobules.

The several tubes forming the coni vasculosi unite ulti-
mately into one tube which continues downward and onward
as the canal of the epididymis.

The epididymis consists macroscopically of a body, a head
or globus major above, and a globus minor below7. The globus
major is intimately connected with the testis by the vasa
efferentia ; the globus minor is attached to the testis by fibrous
tissue ; the body of the epididymis mainly by the tunica
vaginalis.

The body and globus minor of the epididymis are made
up of the windings of the canal of the epididymis, which is
the continuation of the united vasa efferentia. The canal of
the epididymis is a single long continuous tube, coiled, con-
voluted, and packed into small compass ; it is lined with strat-
ified ciliated epithelium, resting on a basement-membrane and

SEMINAL VESICLE. 177

surrounded by fibrous tissue containing transverse involuntary
muscle-cells. The coils of the canal are imbedded in and
separated by areolar tissue, and the whole epididymis is
enveloped in a fibrous capsule. At the lower end of the
epididymis its canal becomes and continues onward as the
vas deferens.

Various remnants of foetal structures (vestiges of the AVolf-
fian body) are found about the testicle.

The paradidymiSj or organ of Giraldes, is situated in the
connective tissue of the epididymis, and consists of a few
closed convoluted tubules lined with epithelium. The vas
aberrans is a tube similar to the vas deferens, and is some-
times found branching^ off from the lower part of the latter,
or canal of the epididymis, passes up the spermatic cord for
a variable short distance, and has a blind upper end. The
hydatids of Morgagni are small pedunculatecl bodies, contain-
ing areolar, epithelial, or vascular tissue, attached to the upper
part of the testis or epididymis.

The vas deferens, the continuation of the lower end of the
canal of the epididymis, forms one of the constituents of the
spermatic cord, and extends to the base of the bladder, where
it becomes dilated (forming the "ampulla") and unites with
the outlet of the seminal vesicle. It is a firm cordy tube,
and its walls consist, from within outward, of a mucous, sub-
mucous, muscular, and fibrous coat.

The mucous coat is lined with stratified columnar epithe-
lium, ciliated for a short distance at the beginning of the vas,
but non-ciliated in the remaining greater portion of the canal ;
the epithelium rests on a tunica propria, which is surrounded
by submucous areolar tissue. The mucosa is thrown into
longitudinal folds in the va§, and in the ampulla into irregular
ruga? and plications. Small glands occur in the mucosa in
the ampulla.

The muscular coat is composed of an inner circular and outer
longitudinal layer of involuntary muscle, intermingled with
fibrous tissue. Outside the muscle is a layer of fibrous and
areolar tissue.

The seminal vesicle is a sacculated pouch, largely of glandu-
lar character, branching off from the vas deferens. Its outlet

12— Hist.

178 THE REPRODUCTIVE SYSTEM.

unites with the vas deferens to form the ejaculatory duct. Its
walls are similar in structure to those of the vas. It is lined
with columnar epithelium, which rests on a tunica propria,
beneath which is submucous areolar tissue. Its mucosa is
thrown into interlacing rugae and plications, which form sac-
cular and somewhat gland-like recesses ; the mucous coat also
contains small glands. Beneath the submucosa is an inner
circular and outer longitudinal layer of involuntary muscle,
outside of which is areolar tissue.

The ejaculatory ducts, one on each side, are formed by the
union of the vasa deferentia with the outlets of the seminal
vesicles. They are situated partly within the prostate, and
empty into the prostatic urethra. They are lined with simple
columnar epithelium, resting on connective tissue ; outside the
latter are thin inner circular and outer longitudinal layers of
involuntary muscle.

The prostate gland is a compound tubular gland, the mu-
cous secretion of which enters into the composition of the
semen. It surrounds a portion of the urethra and ejaculatory
ducts. It is made up of sustentacular connective tissue, invol-
untary muscle, and secreting alveoli, besides vessels and nerves.

The sustentacular connective tissue consists of a firm fibrous
capsule, septa traversing the organ in various directions, and
interalveolar tissue. Intermingled with and accompanying
the connective tissue throughout the organ, forming in many
places the greatest part of its framework, is a large amount
of involuntary muscle, in the capsule and septa, between the
alveoli, and surrounding the urethra.

The glandular alveoli of the prostate are of a racemose or
compound tubular character, and are lined with columnar
epithelium.

Their ducts unite to form twelve to twenty outlet-ducts
opening into the urethra — •/. f., the " prostatic sinus" on each
side ; the epithelium lining the ducts merges into the squa-
mous type of the urethra. Many of the alveoli contain minute
round, concentrically marked calculous granules, or prostatic
concretions. From the lower surface of the urethra a short
small cul-de sac extends into the prostate ; this is called the
sinus pocularis or uterm masculinus, and is homologous to the
female uterus.

CORPORA CAVERNOSA.

179

Cowper' s glands, situated beneath the membranous urethra
between the layers of the deep perineal fascia, are two small
racemose glands emptying into the urethra. The alveoli are
lined with columnar epithelium apparently of the mucous
type, though the purpose of the secretion is not well under-
stood.

The Penis.

The penis consists of three longitudinal cylindrical com-
partments surrounded by fibrous sheaths — two corpora caver-
nosa filled with erectile tissue, and the corpus spongiosum con-
taining erectile tissue and the urethra — all covered with skin

FIG. 69.

Cavernous or erectile tissue of penis (Cadiat). a, fibrous trabeculae ; b, cavernous
sinuses ; c, smooth muscle in cross-section.

and subcutaneous tissue. The skin is thin and movable. The
subcutaneous areolar tissue is free from fat, contains vascular
and nerve trunks, and by its looseness allows the skin much
play.

The corpora cavernosa are surrounded by a common sheath
of dense fibrous tissue, the tunica albuguinea. Each corpus

180 THE REPRODUCTIVE SYSTEM.

cavernosum is also enveloped by a dense fibrous sheath of
its own, lying just within the common sheath J the septum
(u pectiniform ") thus formed between the two corpora is, how-
ever, incomplete and interrupted. From these sheaths fibrous
trabeculse are given off which traverse the interior of the
corpora in all directions, branching and anastomosing so as
to divide them into a spongy system of spaces or sinuses com-
municating freely with one another. The fibrous trabeculce con-
tain some involuntary muscle and elastic tissue, and convey
vessels and nerves. The sinuses formed by the septa are lined
with endothelium, and into them open the bloodvessels, so
that they form a system of cavernous spaces or vascular
sinuses, through which the blood flows, from the arteries and
into the veins (Fig. 69). This arrangement constitutes erectile
tissue. When the venous outflow is cut off by muscular action
blood accumulates in the sinuses, causing the penis to become
turgid and erect.

The corpus spongiosum is a compartment filled with erectile
tissue and containing the urethra. Its posterior end, slightly
expanded, forms the bulb ; its anterior end, the glans penis. It
is enveloped in a firm fibro-elastic sheath containing a small
amount of involuntary muscle. From the sheath fibro-elastic
trabeculge, containing occasional non-striated muscle, traverse
the corpus and divide it into vascular sinuses, forming erectile
tissue like that of the corpora cavernosa. Along the axis of
the corpus spongiosum passes the urethra (more fully de-
scribed above) surrounded by the erectile tissue, which merges
into the submucous tissue of the urethra. The urethra is
lined with columnar epithelium and into it open numerous
mucous urethral glands (the " glands of Littre), which are
scattered about in the erectile tissue of the corpus spongiosum.

The glans penis is an expansion of the anterior extremity
of the corpus spongiosum, covered by closely adherent mucous
membrane. The mucous membrane, continuous with that
of the urethra, is lined with stratified squamous epithelium,
resting upon a tunica propria, the surface of which is studded
with papilla3 containing numerous special sensory nerve-ter-
minals. At the corona and base of the glans the mucous
membrane contains abundant sebaceous glands, the glandulm
odoriferce or glands of Tyson, unassociated with hairs, the

SPERMATOZOA.

181

— c

odorous secretion of which enters into the formation of the
smegma. The raucous covering of the glans is reflected over
the inner surface of the prepuce and at its margin merges
into the skin.

The semen, as finally ejaculated, consists of an immense
number of special cellular elements (spermatozoa) suspended
in fluid (liquor seminis), together with granular, crystalline,
and adventitious matter. The liquor seminis is derived from
various parts of the seminal tract,
especially the seminal vesicles, pros- FIG. 70.

tate, and Cowper's glands. It is a
muco-al numinous fluid containing
various chemical ingredients. It
exhibits fine granular matter (cel-
lular and protoplasmic debris), and,
in small number, cast-off epithelium-
cells, stray leukocytes, clear " hyaline
bodies" from the seminal vesicles,
fat and lecithin particles, and the
small prostatic concretions or " amy-
loid bodies." After standing, crys-
tals are deposited in the semen, es-
pecially characteristic slender octa-
hedral crystals of spermin phosphate.

The spermatozoa of different species
of animals exhibit characteristic dif-
ferences though the general structure
remains similar ; the same is the case
with the homologous pollen of plants.

The spermatozoon of man (Fig. 70)
is made up of a head 3 to 5 fj. long,
a middle piece 5 or 6 // long, and a
tail 40 to 50 // long. The head is
of a flattened oval or pyriform shape,
to the large end of which the middle
piece or tail is attached. The middle piece is a cylindrical
segment more or less distinctly marked off from the tail. The
tail is a long fine filament or flagellum, tapering to a point ; it
possesses an "axial fibre" surrounded (except for a short dis-

— d

— e

Human spermatozoa (Bohm and
Davidpff ). The left figure is a
side view ; the middle figure
a top view, a, head ; 6, cen-
trosome (?) ; c, middle piece ;
d, sheath about axial fibre (e).

182 THE REPRODUCTIVE SYSTEM.

tance at the end) with a protoplasmic sheath. The tail ex-
hibits rapid vibratory movements, by means of which the
spermatozoon is propelled forward.

Spermatozoa are real cells, though of unusual type. The
head is of the nature of a nucleus, while the tail and a pos-
sible protoplasmic envelope about the head may be taken to
be cytoplasm. The chromosomes are " reduced." A very
minute round body detected by some observers just posterior
to the head is perhaps a centrosome.

FEMALE GENITAL ORGANS.

The female genital organs are the ovaries, oviducts, uterus,
vagina, vulva, vestiges of foetal structures, and mammary
glands. The pelvic organs are developed from the embryonic
Wolffian body and duct of Miiller and their epithelium is of
mesoblastic origin.

The Ovary.

The ovary (Fig. 71) consists of a connective-tissue mass or
stroma, in which are imbedded large numbers of developing

FIG. 71.

Section of ovary of cat (Schron). 1, epithelial covering; 1', hilnm; 2, medulla;
8, stroma of cortex ; 4, bloodvessels ; 5, undeveloped ovisacs : 6, 7, 8, developing
Graafian follicles; 9, mature Graafian follicles; 10, corpus luteum.

ova, each in a structure called an ovisac or Graafian follicle ;
the whole organ being covered by an epithelial investment.

OVA. 183

The ova and Graafian follicles occupy the peripheral or cor-
tical portion of the ovary (the " oophoron "), leaving in the
interior a medullary region continuous with the hilum, where
the vessels enter.

The epithelial covering of the ovary is a single layer of
cuboidal or low columnar cells, called " germinal epithelium "
from the fact that the ova are developed from it during fetal
life. This epithelium is continuous with the peritoneal endo-
thelium, the glistening squamous cells of the latter being
here replaced by columnar cells of less lustre.

The stroma of the ovary is a mass of connective tissue,
made up in the cortical region largely of fusiform connective-
tissue cells with scanty intercellular elements. On the surface,
just beneath the epithelial covering, this tissue is condensed
into a layer called the tunica albuginea, continuous and inti-
mately connected with the stroma.

The medullary region and hilum contain the larger vessels,
imbedded in connective tissue of a more ordinary kind, in
which fibrous elements are more abundant.

Scattered about in the stroma (more abundantly in certain
animals than in the human species) are large epithelioid (?)
cells, the interstitial cells, similar to those of the testis. The
ovary is well supplied with bloodvessels, and also possesses
lymphatics and nerves.

The ova (called ovules before impregnation), which occupy
the peripheral zone of the ovary, originate during foetal life
from processes of the germinal epithelium which grow down-
ward and are then cut off, leaving isolated nodules of epithe-
lial cells in the stroma. In each of these nodules one cell,
destined to become the ovum, enlarges, while the other ac-
companying (indifferent) epithelial cells form a capsule about
it and 'develop ultimately into the tunica granulosa of the
mature Graafian follicle. The cortex of the ovary contains
large numbers (estimated by some observers at about 70,000
in both ovaries) of these primitive ovisacs imbedded in the
stroma, each consisting of a large ovule surrounded by a
more or less definite envelope of small epithelial cells. In
the course of ovulation and menstruation these primitive
ovisacs develop as Graafian follicles, and successively mature
and discharge the ovules from the ovary, leaving the remains

184 THE REPRODUCTIVE SYSTEM.

of the follicles visible for a time as corpora lutea. At any
one time the active ovary exhibits a number of Graafian fol-
licles and corpora lutea in different stages of development,
along with a large number of undeveloped ovisacs.

Graafian follicles (or vesicles) : As the primitive ovisacs
develop they enlarge and sink deeper into the ovary. The
fully developed Graafian follicles are spherical or oval cysts
about 4 to 10 mm. in diameter. Each is surrounded by a
condensation of the stroma in which it is imbedded, forming
a vascular connective-tissue investment called the theca fol-
liculi; this is usually described as consisting of two layers, an
outer, called the tunica fibrosa, and an inner, called the tunica
propria. The theca, be it noted, is not really a part of the
Graafian follicle, but is a condensation of the ovarian stroma
surrounding it.

The outer layer of the follicle proper, lying next to the
tunica propria, is the membrana or tunica granulosa, com-
posed of a few layers of small spheroidal nucleated epithelial
cells. This tunic encloses a large cavity which is filled with
an albuminous fluid, the liquor folliculi.

At one point in its circumference the tunica granulosa is
thickened, having a mass projecting inward composed of cells
identical with those which make up the tunic elsewhere ; this
mass or heap of cells is called the discus proligerus, or
cumulus ovigerus. Within this cumulus the ovule is im-
bedded ; the cells in a layer immediately surrounding the
ovule are columnar and arranged in a radiating manner, form-
ing the corona radiata.

The ovule, or ovum (Fig. 72), is a large spherical cell about
.2 mm. in diameter; each Graafian follicle contains one ovule,
rarely two or three. The wall of the ovule is a thin clear
hyaline membrane, showing indistinct radial markings ; it is
variously called the vitelline membrane, zona pellucida, zona
radiata, and oolemma. The cell-body of the ovule, or vitellus,
is a mass of protoplasm infiltrated with fat-particles. The
nucleus of the ovule is a spherical body, often called the
germinal vesicle; within it is a nucleolus, the germinal spot.

Ovulation : The Graafian follicle, when mature, makes its
way to the surface of the ovary, causing a bulging at that
point. The tissues overlying the follicle become thinned,

CORPORA LUTE A. 185

and finally the vesicle ruptures, permitting the ovule to escape
from the ovary and pass into the oviduct. The discharge of
an ovule in this manner takes place regularly and periodically,

FIG. 72.

Human ovule and its surroundings in the ovary (Nagel). a, g, vitelline mem-
brane (zona pellucida and zona radiata) ; b, c, vitellus or cytoplasm of ovule ;
d, nucleus or germinal vesicle ; e, corona radiata ; /, cells of cumulus ovigerus.

comprising the process called ovulation, which stands in a
definite relation with menstruation.

Corpora lutea : The ruptured Graafian follicle after ovula-
tion undergoes a series of retrograde changes, the resulting
structure being called a corpus hiteum.

The wound or cavity of the emptied Graafian follicle
becomes filled with blood from the ruptured vessels, and the
cells of the tunica granulosa proliferate abundantly. From
the fatty degeneration of cells or the transformation of haemo-
globin into haematoidin the structure acquires a yellow color,
whence its name. Into the mass of epithelial cells and blood-
clot grow, from the ovarian stroma, vascular processes of
connective tissue (granulations), giving the body a lobed or
radiate appearance. By the continued growth and contrac-

186 THE REPRODUCTIVE SYSTEM.

tion of the connective tissue, forming a sort of scar or cicatrix,
the corpus luteum is finally obliterated.

The whole process is similar to that by which wounds in
general undergo repair.

The corpora lutea which result when the discharged ovules
are fecundated (the so-called "true" corpora lutea) attain a
larger size and continue in existence a much longer time (for
many months) than do those (the " false " corpora lutea)
when pregnancy does not result.

Obgenesis : The ovary is similar in development to the testicle and
complementary to it in function. Both are organs of high vital
importance, being the essential genital glands and seats of repro-
duction.

The observations made above with respect to spermatogenesis
apply also, mutatis mutandis, to oogenesis, the development of ovules.

The ovary, like the testicle, has an ample blood-supply and a less
conspicuous innervation. These two channels, circulatory and nervous,
are the only apparent means of communication by which conditions
in other parts of the maternal body can influence the ovary and
hence be transmitted to the offspring. That the ovary can in such
way act in sympathy with organs not directly connected with it
is shown by the relations between ovulation, menstruation, and
pregnancy.

As to the transmission of racial and hereditary characteristics from
the ovum of one generation to the ovules of the next through a suc-
cession or continuity of special germ-cells, the same considerations
apply in oogenesis as in spermatogenesis. Some differences in action
of the female and male genital glands may be noticed. All the ovules
discharged by the human female exist in the ovary preformed from
birth ; consequently any acquired characters in the mother, if trans-
mitted to offspring, would have to be impressed upon cells already
formed rather than upon cells to be subsequently developed. The
spermatozoa and spermatogenic cells, on the contrary, are being
continually renewed and developed de novo. Of all the primitive
ovules in the ovaries only a few hundred come to maturity in the life-
time of the human female ; in contrast to this the male produces and
disseminates millions of spermatozoa.

The oviducts, or Fallopian tubes, are conical tubes opening
into the uterus by the small end and into the peritoneal cavity
by the large end, which is fimbriated. The wall of the ovi-
duct consists, from within outward, of mucous, submucous,
muscular, and serous coats. The mucous coat is formed by a
single layer of columnar ciliated epithelium-cells resting on a
firm tunica propria. At the margins of the fimbria3 the

UTERINE MUCOUS MEMBRANE. 187

ciliated cells meet the squamous endothelium -cells lining the
peritoneum. The mucosa is thrown into broad folds or
plications, mostly branching, which project radially into the
lumen of the tube. Between the mucosa and submucosa is a
thin layer of involuntary muscle representing a muscularis
mucosae. The submucous coat is made up of areolar tissue
containing the larger vessels. The oviducts contain no glands.
Outside the submucous coat is a muscular coat, composed of a
thick inner circular layer and a thinner outer longitudinal
layer of involuntary muscle. The outermost or serous cover-
ing of the oviduct is formed by the peritoneum and subperi-
toneal tissue.

Remnants of foetal structures : The parovarium is a series
of tubules lined with simple columnar epithelium, situ-
ated in the broad ligament near the hilum of the ovary
and between the latter and oviduct; they are remains of
tubules of the embryonic Wolffian body. Other similar
tubules, which have received special names, are also sometimes
found in the broad ligament. Pedunculated hydatids (hydatids
of Morgagni), small epithelial sacs, are sometimes attached to
the ovary, parovarium, or a h'mbria of the oviduct.

The Uterus.

The uterus is a hollow, muscular organ, the wall of which
is composed chiefly of involuntary muscle, lined internally
by mucous membrane and externally by serous membrane
(Fig. 73).

The uterine mucous membrane consists of epithelium resting
on a tunica propria which contains numerous tubular glands.
The epithelium lining the uterus is a single layer of short
columnar or cuboidal ciliated cells. The tunica propria is a
layer of connective tissue of an embryonal or growing type,
containing fusiform connective-tissue cells and lymphoid cells
or leukocytes in abundance, with scanty intercellular ele-
ments; it contains abundant bloodvessels, extends downward
to the muscular coat, and in it are imbedded the uterine
glands.

The embryonic character of the connective tissue of the
tunica propria is apparently due to the fact that the latter in

188

THE REPRODUCTIVE SYSTEM.

the course of menstruation is at short intervals cast off and
grows anew.

The uterine glands are numerous tubular glands, mostly
simple and unbranched, extending perpendicularly from the
surface of the mucosa to the muscular coat. Their deeper
portions are convoluted, their superficial portions more

FIG. 73.

Section throrugh wall of a rabbit's \iterus (Schiifer). m, mucosa (the cilia of the
epithelium are not shown) ; a, muscular coat ; s, peritoneum.

straight. They are lined by a continuation of the simple
ciliated epithelium of the mucous surface. Their function is
not so much secretory as to serve as foci for the regeneration
of the epithelium after menstruation.

The muscular coat makes up the bulk of the uterine sub-
stance. It consists of layers and fasciculi of non-striated

PREGNANCY. 189

muscle, imbedded in connective tissue and intermingled with
numerous large arterial and venous channels. The muscular
tissue is arranged in general in three strata, an inner and an
outer longitudinal and a middle circular layer ; but these
divisions are not very distinct and the arrangement is not very
definite.

The outer surface of the uterus is covered with serous mem-
brane, consisting of the folds of the peritoneum reflected over
it. The bloodvessels of the uterus are unusually large,
abundant, and tortuous.

The cervix of the uterus has a thicker mucosa, which is
thrown into rugae, and a more regular arrangement of the
three muscle-layers than the body of the organ.

The upper portion of the cervical canal is covered with
simple ciliated epithelium ; but the loiter poiiion is lined with
stratified squamous epithelium, and the underlying tunica
propria presents numerous projecting papillae.

In the lower part of the cervix mucous glands are present,
in addition to the uterine glands. From the closure of their
outlet-ducts these mucous glands often become distended with
secretion, forming small cysts called ovula of Naboth. The
outer surface of the cervix uteri is lined by the vaginal
mucous membrane.

During menstruation the mucous lining of the uterus be-
comes much thickened ; the epithelium cells swell, the tunica
propria becomes very vascular and increases in thickness, and
the uterine glands enlarge. The mucosa becomes softened
and degenerated, and is finally cast off, mingled with blood,
as the menstrual discharge. After menstruation is over the
mucous membrane is rapidly renewed, the surface epithelium
being regenerated from the portions of the uterine glands
remaining in the depths of the tunica propria.

During pregnancy there is a great hypertrophy or increased
development of the mucous and muscular coats and the vascu-
lar system of the uterus. The mucosa undergoes special
changes and to it become attached the placenta and foatal en-
velopes; it exhibits fusiform connective-tissue cells, large
numbers of decidual cells (large brown pigmented, round, or
polymorphous cells, sometimes multinucleated), dilated and
compressed lumina of the uterine glands, and an increase of

190 THE REPRODUCTIVE SYSTEM.

vascular channels, while the superficial and glandular epithe-
lium becomes disintegrated or much altered. Its inner surface
becomes intimately connected with the placenta and the chorion.
Two layers are distinguished in the mucosa, a superficial
"compact layer'7 and a deeper "cavernous" or "spongy
layer" ; the latter lies next to the muscular wall of the uterus,
and is characterized by containing the distended deeper por-
tions of the uterine glands.

This specially developed mucosa of the pregnant uterus is
called the decidua, and is cast off with the placenta and mem-
branes at the birth of the foetus. The decidua exhibits three
divisions : the decidua serotina, which enters into the forma-
tion of the placenta ; the decidua vera, which lines the non-
placental portion of the inner surface of the uterus, and is
cast off, united to the chorion, as part of the foetal membranes ;
and the decidua reflexa, which in the early part of pregnancy
grows out from the mucosa into the cavity of the uterus and
surrounds the ovum and foetus, but at a later period degener-
ates and disappears. After labor takes place the hypertro-
phied uterus undergoes retrogressive changes and involution
to its ordinary size, and its mucous lining is regenerated from
the remnants of the tunica propria and epithelium left after
the casting off of the decidua.

Foetal Appendages.

The primitive appendages of the foetus are the amnion, chorion,
allantois, and umbilical vesicle, all derived from the embryo, together
with the decidua, which is of uterine origin. The umbilical vesicle is
a rudimentary structure and soon disappears. The amnion, chorion,
and decidua form, in general, from within outward, three envelopes
about the foetus. As fully developed, at term, these structures form the
"after-birth" or " secundines," consisting of the foetal membranes, the
placenta, and the umbilical cord ; these are delivered with the foetus
at birth.

The (internal or true) amnion, the innermost foetal envelope, is a
thin membranous closed sac filled with fluid in which the foetus is im-
mersed. It originates as an outgrowth from the embryo, and consists
of two layers, the innermost (toward the foetus) an epithelial and epi-
blastic layer ; the outer, a mesoblastic (somatopleural) connective-tissue
layer. It is at first separate from the chorion, but afterward becomes
united to it and lines the inner free surface of the foetal membranes and
placenta.

The chorion, the middle envelope, in man originates chiefly from the

FCETAL MEMBRANE. 191

external or "false" amnion (composed of epiblast and somatopleure)
and over a small area from the allantois — besides the vitelline mem-
brane of the ovum, which early disappears. The chorion exhibits
externally (toward the uterine wall) an epiblastic epithelial layer, de-
rived from the external amnion ; and internally a connective-tissue
layer of mesoblastic origin, derived from the amnion and allantois.
The chorion is connected with the foetus by a vascular mesoblastic stalk
(the umbilical cord) made up mainly of the allantois.

The allantois is a saccular outgrowth from the primitive intestine,
extending to the chorion and uniting with the latter over a greater or
less area. It consists of mesoblast (splanchnopleure) externally and
internally has a cavity lined with hypoblast ; in man the portion of
the allantoic cavity beyond the abdominal wall consists only of a small
tube extending into the umbilical cord. The umbilical bloodvessels
are derived from the allantois. The mesoblastic tissues of the allantois
enter into the formation of the chorion and umbilical cord.

At a very early period numerous vascular tufts, chorial villi, grow
out from the chorion on all sides, projecting toward the uterine wall.
A portion of the chorion, called the " chorion frondosum," enters into
the formation of the placenta, the villi of this region undergoing great
development and becoming intimately united with the corresponding
portion of the decidua (the decidua serotina). Over the remainder of
the choriou, the " chorion laeve," the villi disappear, this portion of
the chorion becoming united with the decidua vera to form (with the
amnion) the foetal membranes.

The decidua, already described, is the modified uterine mucosa in
three divisions — the serotina, vera, and reflexa.

The umbilical vesicle, or " yolk sac," in the higher mammals has
little functional value, and soon disappears. It consists of a sac or
vesicle situated between the amnion and chorion, and a pedicle or
stalk in the umbilical cord. In origin it is continuous with the primi-
tive intestine, and consists of a vascular mesoblastic (splanchnopleural)
layer externally, and is lined with hypoblast internally.

The foetal membrane (" bag of waters ") is a thin, translucent mem-
brane given off from the margin of the placenta, forms a closed sac
about the foetus, and is closely applied to the inner surface of the
uterus. It is filled with a quantity of serous fluid, the liquor amnii,
in which the foetus is immersed. It is formed, from within outward,
of the amnion, chorion, and decidua vera.

The amnion is a thin, non-vascular membrane, lined on its free sur-
face (that directed toward the foetus) by simple squamous epithelium,
beneath which is a connective-tissue stratum composed of connective-
tissue cells (chiefly flat, stellate or irregular, many with anastomosing
processes), fibres, and gelatinous intercellular substance. In places the
outer surface exhibits small hexagonal endothelioid cells. The amnion
is loosely connected with the underlying chorion by fibrous strands,
or very delicate muco-fibrous tissue, so that it has some play over the
latter and can be stripped off.

The liquor amnii, which surrounds the foetus and fills the amniotic
sac, is a serous fluid holding proteid and other substances in solution.

192 THE REPRODUCTIVE SYSTEM.

The chorion, the middle constituent of the foetal membrane, exhibits
two layers, an inner fibrous and an outer cellular layer. The fibrous
layer is next to the amnion, with which it is loosely united ; it is of
mesoblastic origin and composed of fibrous tissue. The outer or " cel-
lular layer " consists of several layers of large spheroidal prominently
nucleated cells, apparently of epiblastic origin and epithelial nature.

Externally the chorion is closely united to the decidua vera (the
decidua reflexa degenerating and disappearing by about the seventh
month) ; the decidua vera, the mucosa of the pregnant uterus, at labor
is cast off with the foetal membrane as its outermost lamina.

The placenta is formed by the union of the chorion frondosum and
xiecidua serotina, and hence consists partly of foetal and partly of
maternal tissues. It is essentially an intimate interlacement of foetal
and maternal blood-channels, serving alimentary, respiratory, and
excretory purposes for the foetus. The placenta consists of four layers,
which are, from the foetal surface outward, the amnion, the chorion, a
broad layer of chorial villi separated by maternal blood-sinuses, and
the decidua serotina.

The portion of the amnion lining the foetal surface of the placenta is
continuous with that lining the foetal membranes, and is similar to the
latter in its structure, having a superficial epithelial and deeper con-
nective-tissue layer, and being connected with the chorion by delicate
muco-fibrous tissue.

The placental portion of the chorion (chorion frondosum) presents
toward the amnion a fibrous layer, and beneath this the epithelioid
"cellular layer," as in the chorion Iseve, with which it is continuous;
beneath the cellular layer is a coagulum-like stratum containing pas-
sages and spaces, called the " canalized fibrin."

The substance of the placenta is composed of a mass of "chorial
villi," with intervening maternal blood-spaces, interposed between the
chorion and decidua serotina. On following the foetal membranes into
the margin of the placenta, the chorion and decidua separate, the
interval between them being filled with the villi and sinuses. The
umbilical vessels on reaching the placenta divide and subdivide and
spread over its surface, running in the fibrous layer of the chorion.
The branches of these vessels pass outward from the chorial mem-
brane, toward the uterine wall, forming branching vascular tufts, the
chorial villi, which are covered with an epithelioid investment from
the outer epiblastic layer of the chorion.

The villi begin as large coarse trunks passing from the chorion
toward the decidua; these divide into a great profusion of small
cylindrical branches and twigs. The ends of some of the villi become
attached to the decidua serotina, but most of the branches end in free
or floating blunt, round extremities. The villi are composed of arterial
and venous channels and capillary loops, imbedded in a loose connec-
tive tissue, with their surface covered with tissue of epithelial origin.
The foetal vessels are closed, and nowhere open into the maternal
blood-channels.

The epithelioid tissue lining the surface of the villi consists variously
of distinct cells, a protoplasmic lamina containing numerous nuclei,

VAGINA. 193

or projecting clusters of cells ; this epithelioid investment is derived —
its deeper part at least — from the epiblastic outer layer of the chorion ;
partly also, perhaps, from the epithelium of the uterine mucosa. The
twigs of the villi are separated by open spaces, " intervillous spaces,"
into which the maternal arteries and veins in the decidua open
directly; these spaces thus form an extensive system of blood-sinuses,
filled with maternal blood, into which the chorial villi project. By
interchanges between the foetal blood circulating in the villi and the
maternal blood which surrounds the villi the alimentary and excretory
needs of the foetus are provided for.

The decidua serotina, which is continuous with the decidua vera,
forms the deepest stratum of the placenta ; it is a thin lamina, and
has been already described as the mucosa of the pregnant uterus.
Among its constituents the abundant " decidual cells " are notable.
Septa from the decidua pass part way into the placenta and divide it
into lobes or cotyledons. At the margin of the placenta these
septa mav reach the chorion and form in places a " subchorial decidual
layer."

The umbilical cord is a vascular cord connecting the foetus with the
placenta. It is formed by the stalk of the chorion and allantois,
covered on the surface by the amnion. It consists of two arteries and
one vein, twisted spirally, surrounded by gelatinous embryonic or
young connective tissue (" Wharton's jelly"), and lined superficially
with epithelium. The epithelium covering the surface of the cord is
of the squamous variety, stratified or simple, and is continuous with
the epithelium lining the amnion, also with the foetal epidermis.

In the earlier part of pregnancy the jelly of Wharton or connective
tissue surrounding the umbilical vessels is a mucous tissue, composed
of anastomosing mucous cells with the meshes and interstices between
them filled with a soft mucinous or gelatinous intercellular substance;
toward the close of pregnancy fibrous elements develop abundantly in
the interstices of this tissue. The umbilical vessels possess thick walls,
made up mainly of laminae of involuntary muscle-cells arranged longi-
tudinally, obliquely, and transversely ; elastic fibres are scanty in the
vessel-walls, and the ad ventitia merges into the surrounding Wharton's

Jell.v-

At an early period the cord also contains the cavity of the allantois
and the stalk of the umbilical vesicle, both being tubules lined with
hypoblast ; these structures later disappear, though traces of them
may sometimes remain visible as columns or canals of epithelioid cells.

The vagina : The walls of the vagina are composed of
mucous, submucous, muscular, and fibrous layers, from within
outward. The inner surface is disposed in transverse rugae.
The mucosa consists of stratified squamous epithelium resting
on a tunica propria. The latter contains abundant elastic
fibres and diffuse lymphoid tissue, and its surface exhibits
papillae projecting into the epithelial layer. No glands are

13— Hist.

194 THE REPRODUCTIVE SYSTEM.

present. The submncosa is a layer of loose connective tissue
containing rich vascular plexuses, a sort of erectile tissue.
The muscular coat consists in general of an inner circular
and an outer longitudinal layer of involuntary muscle. The
outermost coat is fibrous, or areolar, connecting the vagina
with the bladder anteriorly and with the peritoneum, rectum,
and perineum posteriorly. Among the nervous elements of
the vagina are special sensory terminals.

The vulva is covered with an integument continuous with
the mucous membrane of the vagina and urethra and with
the external skin. This integument consists of stratified
squamous epithelium, in places pigmented, resting on a papil-
lated tunica propria, beneath which is a loose areolar sub-
mucous layer.

Opening on the surface are numerous small glands, both
mucous and sebaceous ; the latter occur not only on the hairy
portions of the labia majora, but also on the iabia minora
unassociated with hairs.

The glands of Bartholin are two macroscopic racemose
glands, corresponding to Cowper's glands of the male, situated
in the labia minora, one on each side of the outlet of the
vagina. Special sensory nerve-terminals occur in the mucous
membrane in this region.

Beneath the integument of the labia majora are masses of
adipose, areolar, vascular, and muscular tissue ; beneath that
of the labia minora and vestibule is an especial abundance of
vascular plexuses and sinuses, forming an erectile tissue. In
the deeper strata of the genitalia are fasciculi of muscle, both
striated and non-striated, variously arranged.

The hymen is a fold of the vaginal mucous membrane.
The clitoris repeats in a rudimentary way the cavernous and
erectile structure of the penis.

The Mammary Glands.

The mammary glands are fully developed only during their
periods of functional secreting activity, the periods of lacta-
tion; at other times they are in an atrophic non-secreting
condition.

When in the state of active secretion the mammary

SUSTENTACULAR CONNECTIVE TISSUE.

195

is a compound racemose gland, of the fatty type (secreting
also a serous and albuminous fluid), and is situated in the
subcutaneous tissue. It is divided by septa into fifteen to

FIG. 74.

Secreting alveoli of mammary gland of guinea-pig during lactation (Michaelis).

twenty lobes, and these again into lobules, each of which is
made up of a number of the ultimate alveoli (Fig. 74).

Each of the lobes has a separate outlet-duct opening at the
nipple, each lobe thus being essentially a distinct gland.

The sustentacular connective tissue consists of interlobar
septa, interlobular septa, and a small amount of interalveolar
connective tissue lying between the alveoli. Adipose and
areolar tissue is also abundant, filling the intervals between
the lobes and lobules.

The ultimate secreting alveoli are large oval or elongated
saccules, with large open lumina, and are lined with a layer
of granular spheroidal epithelium-cells, which secrete the
milk. Within these cells globules of oil develop and are
discharged into the lumen to form the fat-particles of the
secreted milk.

The alveoli empty into ducts, called lactiferous or galac-

196 THE REPRODUCTIVE SYSTEM.

tophorous ducts, which are lined with a layer of low columnar
epithelium and gradually increase in size as they unite. The
ducts in each lobe unite to form a large outlet-duct, which
pursues a separate course to the nipple, distinct from the other
lobar ducts. These large lobar outlet-ducts have well-marked
walls of fibrous tissue and some unstriped muscle ; toward
the nipple they are dilated so as to form ampullce or sinuses,
which serve as temporary receptacles for the milk, and open
at the nipple by constricted orifices; they are lined with
simple columnar epithelium nearly to the nipple, where the
lining changes to stratified squamous.

The nipple is covered with a sort of mucous membrane,
rosy or pigmented, lined with stratified squamous epithelium,
and containing numerous special sensory nerve-terminals.
Within the nipple is involuntary muscle, to which its erec-
tility is due. Scattered about the base of the nipple and the
surrounding areola are the small racemose glands of Mont-
gomery, especially developed during lactation, which corre-
spond to small projections on the surface.

When not in a condition of active secretion, the alveoli are
smaller, less numerous, rudimentary or atrophic ; instead of
having a cavity their lumen is filled with cells, so that they
are represented by small solid nodules of epithelium.

The system of ducts is present and well formed.

Areolar and adipose tissue is more abundant, taking the
place of the undeveloped or degenerated alveoli, which are
imbedded in this increased amount of connective tissue.

Such is the rudimentary and undeveloped structure of the
mamma in females before the first pregnancy, and in males.

During pregnancy the gland undergoes active development,
especially the secretory alveoli, which increase in number and
size, while the intervening connective tissue is reduced, and
the cells in the centre of the solid alveolar epithelial masses
undergo fatty degeneration and at the beginning of lactation
are perhaps cast oif in the first milk as colostrum-corpuscles.

After lactation is over the gland undergoes retrogressive
changes or involution to its former condition, the alveoli
atrophying and being replaced by adipose and areolar tissue.

Milk, the secretion of the mammary gland, consists micro-

THE ADRENAL OR SUPRARENAL GLANDS. 197

scopicallv of a homogeneous transparent liquid in which are
suspended large numbers of minute round or oval globules
of fat, varying in size from two to five /A These globules
cause the opacity and white color of the milk ; they are sup-
posedly surrounded and kept intact by albuminous (casein)
envelopes.

The milk secreted at the beginning of lactation, the colos-
trum, contains, in addition to the constituents of ordinary
milk, larger spherules of fat and colostrum-corpuscles. The
latter are large cells filled with particles of fat, and are re-
garded by some as epithelium-cells; by others, as wandering
cells which have undergone fatty degeneration.

CHAPTER XV.

MUSCULAR AND SKELETAL STRUCTURES.

IN a logical analysis of the systems of the body, the motor
structures (voluntary) and the framework of the body deserve
equal and coordinate rank and consideration with the other
systems. The elemental tissues which make up the greatest
part of the muscular and skeletal structures have, however,
been already described (Chapter IV.), so that only a few fur-
ther points need attention.

The voluntary muscles are made up of striated muscle-cells
or fibers, united by sustentacular connective tissue into fas-
ciculi, and these again into entire muscles. They are richly
supplied with capillaries. That portion of the sustentacular
tissue enveloping the entire muscle is called the epimysium ;
that investing the several fasciculi is the per imy slum ; the deli-
cate connective tissue within the fasciculi, among the indi-
vidual muscle-cells, is the endomysium.

Tendons consist of white connective-tissue fibres cemented
together in parallel non-vascular dense bundles ; these are
bound together into entire tendons by trabeculse and sheaths
of sustentacular tissue, which contains the vascular supply.
In rows between the white fibres are the tendon-cells, special-
ized connective-tissue cells ; they send flat lamellar projections
between adjacent fibres, thus having a rectangular appearance
from the side, stellate in cross-section. The nuclei of adjoin-
ing cells are often situated near each other, forming pairs.
The surface of tendons is often lined with endothelium.

The connection between the tendons and the muscle-cells is
in general established by the fibres of the endomysium ; these
are united on the one hand to the sarcolemma at the extremi-
ties of the muscle-cells, and on the other are connected with
tendon-fibres. At the junction of muscles and tendons their
connective-tissue elements are continuous and merge into
each other.

198

TEND ON-SHEA THS. 199

Tendons and ligaments at their insertion into bones become
intimately blended with the periosteum, and their fibres often
meet the bony substance obliquely or perpendicularly. Some
of the fibres penetrate the bone for a short distance after the
manner of Sharpey's fibres, so that the osseous tissue and the
tendon-fibres dovetail into each other, affording a very firm

FIG. 75.

Cross-section of portion of tendon (Schafer).

union. These fibrous insertions can be stripped from the
bone only with difficulty, more so than the periosteum else-
where, and the surface of the denuded bone at such points is
rough and uneven.

Synovial membranes, allied to serous membranes, are thin
fibrous membranes more or less completely covered on their
free surface with flat connective-tissue or endothelium cells.
They form sheaths or sacs in connection with moving surfaces,
of three kinds — articular, vaginal, and bursal. The arricular
synovial membranes inclose joints ; the vaginal form tendon-
sheaths ; the bursal line the bursse. They secrete, by a sort
of glandular action, a glairy fluid which lubricates the opposed
surfaces that move on each other.

Tendon-sheaths : The tendons in some situations, in the
vicinity of joints, notably in the hand and foot, are sur-

200 MUSCULAR AND SKELETAL STRUCTURES.

rounded by synovial sheaths or sacs in which they smoothly
glide.

Bursae are small synovial sacs situated at points exposed to
friction ; they facilitate movement by the gliding of their
opposite surfaces over each other, lubricated by their glairy
contents. They occur at exposed points underneath the skin,
as over the patella, and interposed between tendons and bones,
as over the bicipital tuberosity of the radius.

The structure of bones and cartilages, which make up the
chief part of the skeletal framework, has been already suf-
ficiently considered.

The ligaments, which bind the parts of the skeleton together,
mostly consist of dense white fibrous tissue, and are character-
ized by firm, unyielding strength ; a few ligaments, however,
the ligamentum nuchse of animals and the ligamenta subflava
of the spine, consist of elastic tissue and are serviceable by
virtue of their elasticity.

Fasciae are chiefly composed of interlacing white fibrous
tissue.

The articulations of the bones with one another are of three
kinds — synarthroses, in which the joint is immovable ; amphi-
arthroses, in which there is limited motion ; and diarthroses,
in which motion is more or less free.

The synarthroses, or immovable joints, are exemplified by
the bones of the skull and face, immovably united or dove-
tailed together by sutures.

In the amphiarthroses a layer of fibro-cartilage is interposed
between the uniting bones (forming a " synchondrosis "), the
articulation being reinforced by ligaments. There is no synov-
ial joint-cavity and no surfaces moving on each other, the
limited amount of motion possible being effected by the flexi-
bility of the cartilaginous junction. The inter vertebral junc-
tions and the pubic and sacro-iliac symphyses are amphiar-
throdial joints.

The intervertebral discs contain in their centre a pulpy
reticular mass, the remains of the chorda dorsalis ; outside
of this is a broad zone composed of lamina? of fibro-carti-
lage, which merges at the periphery into dense white fibrous
tissue.

The diarthroses, or ordinary joints, are characterized by the

DIARTHROSES. 201

possession of synovial cavities and the movement of the ends
of the bones on one another.

The articular ends of the bones entering into the formation
of the joint are covered with a layer of hyaline cartilage, which
takes the place of a periosteum. The articular surface of this
cartilage is smooth, polished, and naked, not being covered by
perichondrium, synovial membrane, or endothelium ; the
superficial cartilage-cells are flattened, the deeper ones often
arranged in rows perpendicular to the surface; the deepest
stratum of the cartilage is calcified.

At the margins of the joint the articular cartilages are con-
tinuous with synovial membrane, which closes the sides of the
joint, and together with the cartilages completely incloses and
lines the joint-cavity.

Beneath the synovial membrane is areolar and fatty tissue,
filling in the spaces between the bony parts.

The synovial membrane in places projects into the cavity as
vascular, fatty, or fibrous ridges, fringes, or villi.

The exterior of the joint, outside the subsynovial tissue, is
firmly bound together by ligaments. In some joints the mar-
gins of the articulating surfaces are deepened by rims ofjibro-
cartilage, as in the shoulder (glenoid ligament), hip (cotyloid
ligament), and knee (semilunar cartilages).

CHAPTER XVI.

THE NERVOUS SYSTEM.

THE nervous system is the seat and apparatus of sensation,
consciousness, coordination, and volition, and its elements are
distributed throughout all parts of the body. Nervous tissues
are of epiblastic origin and constitute a class of tissues sui
generis.

Division : The nervous system can for practical convenience
be divided into the nerve-centres, nerve-trunks, and distal
nerve-terminals ; and the tissue-elements corresponding to
these respectively are nerve-cells, nerve-fibres, and nerve-
terminals.

The cells and centres are concerned with the distribution
and storage of nervous energy; the fibres conduct nervous im-
pulses; and the terminals are connected with the transfor-
mation of nervous force into other forms of energy, and vice
versa.

According to present prevailing conceptions, the structural
and functional units of the nervous system are elements called
neurons, and the subject is here presented from this stand-
point. A neuron is a single nerve-cell with all its parts and
processes. The nerve-fibres are regarded as greatly elongated
processes of nerve-cells, so that a neuron would include the
body of the nerve-cell, its nearby processes, the nerve-fibre
connected with it, perhaps extending a long distance to the
periphery of the body, and the peripheral terminations of the
nerve-fibre. A neuron therefore simply represents a single
complete nerve-cell with all its parts.

Nerve -cells.

Nerve-cells (or ganglion-cells) : In the full sense of the term
" cell," a nerve-cell is the same as a neuron ; but as ordinarily

202

NERVE-CELLS. 203

used the terra nerve-cell is conveniently applied to the main
body of these cells, regardless of the extended processes.
Such a term as neurosome would, perhaps, be a better desig-
nation for the nerve-cell body. Nerve-cells are ordinarily of
large size, and are situated in the ganglia and cerebro-spinal
centres. Their cytoplasm usually consists of a network of
fibrils (spongioplasm), in the meshes of which is a more fluid,
homogeneous protoplasm (hyaloplasm), sometimes called
neuroplasm.

The cell-bodies often contain granules (chromophilic gran-
ules) which stain deeply with various dyes, especially basic
stains ; pigment is also sometimes present. There is no definite
cell-envelope.

Nerve-cells possess each a large vesicular nucleus, usually
poor in chromatin, and hence not staining deeply ; within the
nucleus is a large nudeolus. In shape nerve-cells vary, being

FIG. 76.

Body of multipolar nerve-cell from spinal cord (Nissl's stain), showing details of
the structure (Ramon y Cajal). a, neurite; 6, c, cytoplasm, containing coarse
chromophilic granules ; d, nucleus, with nucleolus ; e, dendrite.

spherical (ganglia), oval, fusiform, pyramidal (cerebrum), or
stellate (spinal cord).

204

THE NERVOUS SYSTEM.

Nerve-cells are strongly characterized by the possession of
processes, often greatly prolonged and very complex, ranging
in number from one to many ; at least one process is always
present. The processes consist largely of prolongations of
the spongioplastic fibrils of the cytoplasm.

Nerve-cells are classed as unipolar, bipolar, and multipolar
according as they possess one, two, or several processes re-
spectively. Another variety of ganglion-cell, which may

FIG. 77.

Nerve-cells from cerebral cortex (Ramon y Cajal). A, small pyramidal nerve-cell ;
B, large pyramidal nerve-cells; C, D, polymorphous nerve-cells; G, neurite; E
and F, fibres in white matter. The arrows indicate directions of nerve-impulses.

be called pseudo-unipolar, is apparently unipolar, but prac-
tically bipolar; it possesses a single process which soon
divides like a T into two processes ; embryonically this cell is
bipolar.

NEURITES. 205

The processes of nerve-cells are of two very distinct kinds,
dendrites or protoplasmic processes, and neurites or axis-
cylinder processes.

The dendrites, or protoplasmic processes, are long slender ex-
tensions or processes from the body of the nerve-cells, usually
dividing and subdividing into branches like a tree, forming
extensive "arborizations" in the vicinity of the cell. As
they divide, the branches decrease in size to fine terminal
twigs, which have either pointed or rounded ends. The ter-
minals of dendrites have been called teledendrites. The num-
ber of dendrites given off by each nerve-cell varies ; there may
be none or several. The cerebro-spinal nerve-cells possess the
most numerous and best developed dendrites, each having a
number of such processes, while the cells of the ganglia are less
abundantly supplied with them, and unipolar cells lack them
altogether. The dendrites of neighboring nerve-cells inter-
lace and lie in close relation with one another ; but according
to the neuron theory they are not actually united or structu-
rally continuous together.

The neurites, axis- cylinder processes, or neuraxons, are
slender filamentary processes from nerve-cells, which are pro-
longed as, and become continuous with, the axis-cylinders of
nerve-fibres, and as such are greatly prolonged, often extend-
ing to the periphery of the body. They acquire medullated
envelopes at a short distance from the cells, and thus become
converted into nerve-fibres. Sometimes, within the substance
of the nerve-centres, neurites give off delicate, short lateral
branches, the collateral fibres, but aside from these and except
at their distal ends neurites do not branch, and their diameter
is uniform throughout. All nerve-cells possess one neurite,
sometimes more than one ; if a cell has but one process, that
process is a neurite.

At their distal ends neurites or nerve-fibres usually termi-
nate in fine branches; these distal terminations have been
called teleneurites. According to the length of the neurites
and the situation of the teleneurites, two types of nerve-cells
or neurons are recognized.

Nerve-cells of the first type have long neurites extending
to the visceral, distal, or peripheral portions of the body,
where their terminals or teleneurites are situated.

206 THE NERVOUS SYSTEM.

Those of the second type have a short neurite which does
not emerge from the nerve-centres, but not far from its
origin divides into its terminal branches or fibrils, — some-
times forming a basket-like network enveloping another
nerve-cell. Neurons of the second type are situated entirely
within the nerve-centres, those of the first type partly within
the nerve-centres, partly without, in the general body-struct-
ures.

A neuron typically consists of a nerve-cell or cell-body, one
or more dendrites, and a neurite prolonged as the axis-cylinder
of a nerve-fibre to the distal part of the body (or to
another part of the nerve-centres), where it has a special
termination.

From the nature of nervous action, as we conceive it, a
neuron must have a mechanism both for receiving nervous
impulses and for sending them out again. Each neuron is
supposed to be complete in itself, and to have no anatomical
connection or continuity with other neurons ; the processes of
one nerve-cell are believed not to be united to those of
other cells.

As it is evident that some communication of nervous impulses
takes place from one neuron to another, it is supposed that
such communication occurs through contact of the processes
or other parts of different cells with one another. If the cell-
processes are retracted (as by amoeboid movement) or diseased,
the communication may be cut off and altered nervous condi-
tions result.

Another conceivable mode of transfer of nervous impulses
from one cell to another, possible without direct contact or
continuity, might be by a sort of induction, analogous to
electric induction.

Function of dendrites and neurites : It is by some supposed
that the dendrites are afferent or centripetal (cellulipetal) in
their action, conducting impulses to the nerve-cell, and that
the neurites are efferent or centrifugal (cellulifugal), convey-
ing impulses from the cell and degenerating when their con-
nection with the cell is severed ; this supposition is clear
enough with respect to motor and other efferent nerve-cells
and fibres, but it is not so obvious in the case of sensory and
afferent fibres,

AXIS-CYLINDER.

207

FIG. 78.

Nerve-fibres.

Nerve-fibres are regarded as processes of nerve-cells, being
the continuations of neurites, enveloped
by certain sheaths. They connect nerve-
cells with nerve-terminals, and their func-
tion is the conduction of nervous impulses.
Nerve-fibres are situated both within and
without the cerebro-spinal centres, with
certain differences in their envelopes in the
two situations. In their passage through
the body the fibres are united by sustentac-
ular tissue into bundles, the nerves or nerve-
trunks. Nerve-fibres are of two kinds,
medullated and non-medullated.

Medullated nerve-fibres (Fig. 78), also
called myelinic or white fibres, make up the
chief part of the cerebro-spinal nerves and
occur also in large numbers in the cerebro-
spinal structures. Where most developed
they consist of three parts — axis-cylinder,
medullary sheath, and neurilemma. Within
the cerebro spinal centres there is no neuri-
lemma, and at the terminations of the fibres
both neurilemma and medullary sheath are
wanting.

The axis-cylinder, or axon, the prolonga-
tion of a neurite, is a fine continuous fila-
ment, uniform in size, occupying the centre
or axis of the fibres. In medullated fibres
the axis-cylinder does not branch except for
the " collateral fibres," and near its distal
termination, where it may divide at a node
of Ranvier. It exhibits fine longitudinal
striations, apparently representing spongio-
plastic fibrilla? bound together by cement or
protoplasm. It is the essential and conduct-
ing portion of the fibres, the medullary sheath and neurilemma
serving as coverings for it. [&J. its central end the axis-
cylinder emerges as a process from a nerve-cell, and at its

Segment of a medul-
lated nerve-fibre, a,
node of Ranvier;
6, neurilemma : c,
medullary sheath ;
rf, axis-cylinder; e,
incisure of Schmidt;
/, nucleus of neuri-
lemma.

208 THE NERVOUS SYSTEM.

distal extremity usually breaks up into branches or fibrils
connected with terminal structures. Axis-cylinders are of
epiblastic origin, developing as outgrowths from the primitive
nerve-cells.

The medullary sheath, or white substance of Schwann, is
an envelope of semisolid material investing the axis-cylinder,
the presence of which is the main feature distinguishing
medullated from non-medullated nerve-fibres. It begins near
the exit of the neurite from the nerve-cell and extends nearly
to the distal termination of the fibre. It protects and per-
haps insulates the axis-cylinder. The medullary substance
consists of an oily, refraetile, semifluid substance called
my din, supposed to be supported in a reticulum or sheath of
a horny substance termed neurokeratin.

At regular intervals the nerve-fibres exhibit constrictions,
the nodes of Ranvier, dividing the fibres into internodal seg-
ments. At these nodes the continuity of the medullary sheath
is interrupted, the neurilemma and axis-cylinder coming
together at these points. In each internodal segment the
medullary sheath exhibits a number of oblique or conical
markings or divisions, called the incisures of Schmidt or of
Lantermann; the nature of these is not definitely known.

The neurilemma, or sheath of Schwann, is a thin homo-
geneous membrane forming the outer covering of the nerve-
fibre. It is present only in the portion of the fibres included
in the nerve-trunks, being absent in the cerebro-spinal centres,
where its place is taken by neuroglia. It also disappears
at the nerve-terminations. At the nodes of Ranvier it comes
into contact with and is cemented to the axis-cylinder, inter-
rupting the continuity of the medullary sheaths at those
points. At the middle of each internodal segment a nucleus
surrounded by a small amount of protoplasm is situated
beneath the neurilemma. This nucleus apparently belongs
to the neurilemma, and each nucleated segment of the neu-
rilemma is commonly regarded as a specialized single connec-
tive-tissue cell.

Non-medullated nerve-fibres, also called amyelinic or gray
fibres, or fibres of Remak (Fig. 79), possess no medullary
sheath. The sympathetic nerves are made up chiefly of this
kind of fibres. They consist in general of axis-cylinders

NEUROGLIA.

209

covered apparently by a neurilemma which exhibits numerous
nuclei. The axis-cylinders are similar to those of medullated
fibres, except that they freely divide
and anastomose with one another, FlG; 79-

forming plexuses. On their surface
at intervals rest nuclei ; these prob-
ably belong to a neurilemma, which,
however, is so thin and delicate as to
be difficult to distinguish.

Nerve-centres.

The nerve-centres are the cerebrum,
cerebellum, and spinal cord, making
up the cerebro-spinal structures ; and
the numerous ganglia in different parts
of the body.

The characteristic elements making
up the central nervous structures are
nerve-cells and processes, nerve-fibres,
and a peculiar sustentacular tissue
called neuroglia.

The pia mater also contributes a
certain amount of ordinary connec-
tive tissue to the sustentacular frame-
work.

Through differences in the distri-
bution of these elements two parts
are distinguishable in the substance
of the cerebro-spinal structures, gray
matter and white matter.

The gray matter consists of neu-
roglia, nerve-cells, ramifying den-
d rites, and scattered nerve-fibres, with and without medullary
sheaths.

The white matter is an almost solid mass of parallel medul-
lated fibres, supported by neuroglia.

Neuroglia, the chief sustentacular tissue of the cerebro-
spinal structure, "is a sort of connective tissue, but is of
epiblastic origin and derived from epithelial elements. It
14— Hist.

Non-medullated nerve-fibres
(Key and Retzius). n, nu-
clei of neurilemma; m, a
fibre which has a partial
medullary sheath.

210 THE NERVOUS SYSTEM.

forms a framework supporting the nervous elements. It

KIG. 80

Spider-cell.
Neuroglia-cells, Golgi stain (Andriezen).

consists of numerous cells (" glia-cells "), possessing very

GRAY MATTER OF THE CEREBRAL CORTEX. 211

many fine processes which interlace with one another to
form a network. Some glia-cells, the "spider-cells," have
long, fine unbranched processes ; others, the " mossy cells,"
have shorter, thicker, and branching processes (Figs. 80, 81).
A homogeneous intercellular cement-substance is perhaps also
present, contributing to the sustentacular framework.

The cerebro-spinal meninges are the dura mater, arachnoid,
and pia mater.

The dura mater is a dense fibrous membrane forming the
outer covering of the brain and spinal cord ; its inner surface
is lined with endothelium. Within the cranium it is closely
applied to the cranial bones, forming their inner periosteum.

The arachnoid is a delicate connective-tissue lamina and
reticulum. Externally it presents a continuous free surface
lined with endothelium ; this surface is opposed to the dura
and separated from it by a large lymph-space, the subdural
space. The deeper portion of the arachnoid is a network of
delicate fibrous lamina? and cords, lined on their free surfaces
with endothelium ; this network is connected and continuous
with the pia mater, and the cavities enclosed in it form a
system of communicating lymph-spaces, called the subarach-
noid space.

The pia mater intimately invests and follows the surface of
the brain and cord ; it consists of delicate vascular connective
tissue, often containing irregular pigment-cells. At intervals
it sends supporting fibrous trabecula? inward into the sub-
stance of the brain and cord.

The Cerebrum.

The cerebrum consists of aggregations of white and gray
matter.

The ivhite matter is composed of radiating masses of medul-
lated nerve-fibres, and occupies the interior and central por-
tions of the organ.

The gray matter, containing the nerve-cells, covers the sur-
face of the cerebrum and also occurs in the central and basal
ganglion ic tracts.

The gray matter of the cerebral cortex in general (though
with variations in some situations) exhibits the following

212

THE NERVOUS SYSTEM.

FIG. 82.

layers (Fig. 82), which are not sharply marked off from one
another. Beneath the pia mater on the surface is a narrow molec-
ular zone, consisting of neuroglia, glia-cells, terminal branches

of nerve- cell processes, and fine
medullated fibres running tan-
gentially or parallel to the surface.
Beneath this is a zone character-
ized by the presence of small
pyramidal nerve-cells. These are
long pyramidal cells, with their
apices directed toward the sur-
face. Each cell gives off an axis-
cylinder process from its base,
running (for the most part) into
the white matter beneath. From
the angles at the apex and base
of the cell are given off dend rites
which divide into branches in the
vicinity. This layer merges be-
low into a broad zone character-
ized by large pyramidal nerve-
cells, similar to those just de-
scribed, but of larger size. Be-
neath this zone is a layer contain-
ing polymorphous nerve-cells of
various shapes — stellate, irregu-
lar, and fusiform. Neuroglia-
cells are scattered about among
the nerve-cells in the various
zones.

The foregoing layers comprise
the cortical gray matter. Be-
neath them is the white matter of the interior, which at regu-
lar intervals sends slender, tapering bundles of medullated
fibres radiating into the lower layers of the gray matter.

The ganglionic parts of the cerebrum, as the corpus striatum,
optic thalamus, corpora quadrigemina, olfactory bulb (or
nerve), consist of gray and white matter variously distributed,
with nerve-cells of various forms — multipolar, stellate, fusi-
form, etc.

Nerve-cells of cerebral cortex (Ca-
jal). 1, molecular zone ; 2, small
pyramidal nerve-cells ; 3, large
pyramidal cells ; 4, polymor-
phous cells ; 5, white matter.

GRAY MATTER OF THE CEREBELLAR CORTEX. 213

The crura cerebri, pons, and medulla oblongata are composed
largely of white matter, or bundles of nerve-fibres passing
into the cerebrum and cerebellum, intermingled with tracts of
gray matter.

The ventricles of the brain, continuous with the central
canal of the spinal cord, are mostly lined with " ependyma" a
single layer of columnar epithelium, ciliated (especially in
youth), resting upon a neurogliar basis. The columnar cells
are related to the glia-cells.

In various parts of the brain are found corpora amylacea,
minute rounded granules with concentric markings, resembling
starch-granules in appearance and chemical reactions.

The Cerebellum.

The central portion of the cerebellum is a mass of white
matter, within which is an irregular nodule of gray matter,
the dentate body. Other nodules of gray matter occur in the
upper part of the organ.

The superficial portion of the cerebellum is divided into
branching laminae, which in cross-section appear like the
branches of a tree, whence they are called the arbor vitse.
These Iamina3 consist of a central core or axis of white matter,
covered on each side with gray matter.

The gray matter of the cerebellar cortex exhibits two well-
marked layers, the nuclear layer and the molecular layer,
between which is a stratum formed by the bodies of the cells
of Purkinje.

The nuclear or granule layer is a broad zone lying next to
and on each side of the central white matter, and contains a
crowded mass of small multipolar nerve-cells with prominent
deeply staining nuclei and small cell-bodies. Scattered about
among these cells are a few larger multipolar nerve-cells and
glia-cells, while mednllated nerve-fibres passing into the cen-
tral white matter are numerous throughout the nuclear layer.

The cells of Purkinje, or " antler-cells/' are conspicuous
nerve-cells, the bodies of which, separated by intervals, are
disposed in a single layer at the junction of the nuclear and
molecular layers. Their bodies are very large, rounded or
flask-shaped, nucleated, nucleolated, and from their superficial

214 THE NERVOUS SYSTEM.

aspect (that directed toward the surface) give off coarse proto-
plasmic processes which divide and subdivide (in narrow
transverse planes) into extensive arborizations occupying the
entire thickness of the molecular layer; from the deeper
aspect each cell gives off an axis cylinder process which passes
inward through the nuclear layer.

The mokcular layer is the superficial stratum of the cere-
bellar cortex, and consists chiefly, besides neuroglia, of the
extensive interlacing ramifications of the dendrites of the cells
of Purkinje and of the processes of other nerve-cells in the
vicinity. This layer also contains scattered small multi polar
nerve-cells ; the neurites of some of these cells (" basket cells")
run parallel to the surface and give off branches which break
up into terminal basket-like networks of fibrils that surround
the bodies of Purkinje's cells.

The Spinal Cord.

The spinal cord is divided into symmetrical lateral halves by
the deep and narrow posterior median " fissure " (really a
fibrous septum) and the broad but shallower anterior median
fissure.

The periphery of the cord is formed by white matter, con-
sisting of a dense mass of longitudinal medullated nerve-
fibres, supported by neuroglia and narrow connective-tissue
extensions from the pia mater passing radially inward. The
narrow layer of white matter intervening between the gray
commissure and the fundus of the anterior median fissure con-
stitutes the "anterior" or "white commissure."

From physiological and pathological considerations the
white fibres of the cord are divisible into definite longitudinal
tracts, but these divisions are only partially apparent to sight
in the normal cord (Fig. 84).

The interior of the cord is occupied by gray matter, which
consists of two lateral parts, curved outward, joined by a
transverse portion (the "gray commissure"), thus in cross-
section roughly exhibiting an H shape.

The gray matter is composed of neuroglia, interlacing den-
drites, nerve-fibres (with and without medullary sheaths), and
nerve-cells.

NERVE-CELLS.

215

The portions of the gray matter which approach the surface
of the cord anteriorly and posteriorly are called the anterior
(or ventral) and posterior (or dorsal) horns or cornua ; the
anterior horns are broader and shorter ; the posterior longer
and narrower.

From these horns at intervals proceed the posterior (sensory)
and anterior (motor) roots of the spinal nerves.

Cross-section of the spinal cord of a newborn child, showing the distribution within
the gray matter of the collaterals from the neurites of the white matter (R. y
Cajal ). a, anterior fissure ; B, pericellular branches of the collaterals from the
anterior column ; C, collaterals of the anterior commissure ; D, posterior bundle
of collaterals in the posterior commissure ; E, middle bundle of the posterior
commissure ; /, anterior bundle ; G, collaterals from the posterior column ; H,
senso-motory collaterals from the posterior column ; I, pericellular terminations
of collateral's in the posterior horn ; J, collateral terminations in the column of
Clarke.

The nerve-cells of the cord (Fig. 76) are arranged in definite
longitudinal series or columns, as follows : (a) in the anterior
horn are numerous very large stellate multipolar motor cells ;

216

THE NERVOUS SYSTEM.

in the posterior horn are smaller and less numerous nerve-
cells ; (c) the vesicular column of Clarke is a column of medium-
sized nerve-cells, not continuous along the entire cord, on the
inner sides of the posterior cornua ; (d) the intermedio-lateral
column is a series of small nerve-cells laterally situated (in the
" lateral horn ") in the dorsal portion of the cord.

FIG. 84.

Cross-section of human spinal cord, middle dorsal region (Rchafer). a, 5 c, nerve-
cells of anterior horn ; d, intermedio-lateral column of nerve-cells ; /, nerve-
cells of Clarke's column ; g, nerve-cells of posterior horn ; cc, central canal ; ac,
anterior white commissure.

The central canal is a small tube in the middle of the gray
commissure extending the whole length of the cord and con-
tinuous with the ventricles of the brain ; it is lined with a
single layer of columnar epithelium-cells, ciliated in youth,
surrounded by neuroglia.

The neuroglia capping the posterior horns and surrounding
the central canal — the " substantia gelatinosa " — is somewhat
homogeneous and glistening.

Ganglia.

Ganglia are small macroscopic to microscopic aggregations
of nerve cells and fibres, occurring abundantly in various
parts of the body. Since they contain nerve-cells, their

ARRANGEMENT OF NERVES. 217

nature and function are essentially those of nervous centres.
Some of them belong to the cerebro-spinal system of nerves
— e. f/.j most of the ganglia connected with the cerebral nerves
and those on the posterior roots of the spinal nerves ; others
pertain to the sympathetic system, as the lateral and anterior
spinal and the visceral ganglia.

Typical ganglia are enveloped in a fibrous capsule continu-
ous with the epineurium of the tributary nerves. The nerve-
ceils in the ganglia are aggregated in elongated or rounded
clusters, separated by bundles of (rnedullated or non-medul-
lated) nerve-fibres. Each nerve-cell is surrounded by a
membranous nucleated capsule, composed of connective-tissue
cells, continuous with the neurilemma of the issuing nerve-
fibre.

The ganglia of the posterior roots of the spinal nerves con-
sist of medullated fibres and large globular encapsulated
nerve-cells, nucleated and nucleolated. In man these nerve-
cells when mature possess a single process which at a short
distance from the cell divides like a T into two branches
going in contrary directions ; these cells are practically bipolar,
as they actually are morphologically in some animals and
the human embryo.

The sympathetic ganglia similarly consist of nerve-fibres
(non-medullated and medullated) and nerve-cells. The latter
are encapsulated, multipolar, often pigmented, occasionally in
man (regularly in some animals) possessing two nuclei. Many
of the sympathetic ganglia are very minute, imbedded in the
substance of the viscera, as the heart and the intestines.

The Nerves.

The nerves, or nerve-trunks, consist of bundles of nerve-fibres
bound together by sustentacular connective tissue.

The cerebro-spinal nerves consist mainly of medullated
fibres ; the sympathetic nerves chiefly of non-medullated fibres.

The arrangement of nerves (especially the cerebro-spinal)
corresponds to that of voluntary muscle. The individual
fibres are grouped in bundles or " funiculi " ; and these again
into the entire nerve-trunks (except in small nerves consisting
of single funiculi). The entire nerve is enveloped in a con-

218 THE NERVOUS SYSTEM.

nective-tissue sheath, called the epineurium. The separate
funiculi are surrounded by similar fibrous sheaths, the
perineuriwn, continuous with the epineurium. Within the
funiculi is a delicate connective tissue, the endoneurium, pene-
trating among the individual nerve-fibres.

The larger blood and lymphatic vessels are situated in the
perineurium and send capillaries into the endoneurium. In
the small terminal nerves the epineurial covering consists of
a layer of flattened connective-tissue or endothelioid cells,
called the " sheath of Henle."

Nerve-terminals.

The axis-cylinders of nerve-fibres at their distal terminations
lose their coverings and divide into fine terminal fibrils, or
" teleneurites." Some of these terminals are situated in the
gray matter of the nerve-centres, and are distributed in a
manner analogous to the dendrites ; others are distributed
throughout the tissues of the body (somatic terminals), and
are often associated with special structures exhibiting great
diversity and specialization of function and form ; some of
them being highly developed and complex organs, such as the
eye and ear.

From a functional standpoint these somatic terminals can
be divided into two classes, afferent and efferent.

The afferent nerve-terminals have sensory functions and
initiate nerve-impulses which travel along the fibres to the
nerve-cells.

The efferent terminals receive impulses (motor, secretory,
trophic, etc.) from the nerve-cells and impart them to the
organs with which they are associated.

In general, the function of the somatic terminals is con-
nected with the transformation of other forms of energy into
the particular mode of molecular energy which constitutes
nervous force ; and with the retransformation of the latter into
ordinary modes of motion.

Classes of nerve-terminals: Only the nerve-endings found
in man are here considered ; other terminals of similar gen-
eral type occur in other animals.

The first division of teleneurites is into those situated in

TERMINAL FIBRILS. 219

the nerve-centres (which do not here require further consider-
ation), and those situated outside the nerve-centres (somatic).
The somatic nerve-terminals of man may be classified thus :

Efferent:

Terminal fibrils ;

Motor end-plates of voluntary muscle.

Afferent :

Terminal fibrils ;

Tactile cells;

Tactile corpuscles of Wagner (or Meissner) ;

- Touch, etc.

End-bulbs of Krause ;

Corpuscles of Pacini (or Vater) ;

Taste-terminals ;

Olfactory terminals;

Eye;

Ear.

Terminal fibrils constitute the simplest form of nerve-end-
ings, and are widely distributed, penetrating among the cells
of the tissues involved (Fig. 85). They are continuations of
the axis-cylinders of the nerve-fibres, which lose their cover-
ings and break up into fine naked terminal fibrils. They
often exhibit bulbous enlargements at intervals, and end in
bulbs or points. They divide and branch, and in some places
anastomose to form plexuses. They are either efferent or af-
ferent.

The chief examples of efferent fibrillar nerve-endings are
found in involuntary muscle, the heart, and secretory glands.

Non-striated muscle (as in the intestine and arteries) is usu-
ally associated with plexuses (sometimes gangliated) of non-
medullated fibres, delicate fibrils from which innervate the
muscle-cells.

The heart-muscle is similarly innervated.

In many glands, as the salivary, delicate plexuses surround
the acini and probably send fibrils (apparently efferent and
stimulant to secretion) among the individual epithelium-cells.

Afferent (sensory) terminal fibrils occur in the epidermis,

220

THE NERVOUS SYSTEM.

mucous membranes, voluntary muscle, and doubtless in many
other situations.

In the epidermis fibrils enter from the corium and are dis-
tributed among the cells of the Malpighian layer. Similar
endings have been found in the epithelium of the mucous mem-

FIG.

Terminal nerve-fibrils in epithelium of mucous membrane (bladder of rabbit)

(Retzius).

brane of the mouth, and occur in mucous membranes else-
where.

The cornea contains delicate terminal plexuses sending
fibrils into the overlying conjunctival epithelium.

In voluntary muscles fine terminal nerve-fibrils of sensory
nature have been demonstrated.

Motor end-plates of voluntary muscle (Fig. 86) : The motor
innervation of striated muscle is derived through " end-plates,"
which are terminals of medullated nerve-fibres.

The end-plate, of which each muscle-cell possesses one, ex-
ceptionally more, is closely attached to the surface of the

TACTILE CORPUSCLES OF WAGNER. 221

muscle-fibre, in intimate relation with the muscle-protoplasm ;
whether it lies underneath or external to the sarcolemma is
unsettled. The end-plates are flattened and elliptical in form,
and are made up of terminal branches of the axis-cylinder
supported by a protoplasmic plate or " sole." The sole is a
mass of granular protoplasm containing a number of nuclei,
and forms a bed or basis for the terminal nerve-branches.

The nerve-fibre concerned, on reaching the end-plate, loses
its medullary sheath, and its axis-cylinder divides into branches,
enlarged and club-shaped, which ramify in an arborescent
way over the end-plate, supported on or imbedded in the sole.

FIG. 86.

End-plate of striated muscle-fibre of a squirrel's tail (Galeotti and Levi).

Tactile cells occur scattered about in the lower part of the
Malpighian layer of the epidermis, and have a tactile function.
Each of them consists of an oval nucleated cell with its lower
surface resting in a meniscus, a concavo-convex or saucer-shaped
expansion of the end of a terminal nerve-fibril. Terminals of
this type are sometimes called " simple tar-tile cells," in con-
tradistinction to " compound tactile cells " (corpuscles of
Merkel and of Grandry), not found in man, in which two
or more cells are together associated with terminal nerve-
plates.

The cells of Langerham, stellate cells occasionally found in
the epidermis, are by some regarded as nerve-terminal cells,
by others as wandering leukocytes.

Tactile corpuscles of Wagner (or Mdssner] : These are ellipti-
cal structures situated in some of the papillae of the corium of

222

THE NERVOUS SYSTEM.

the skin (Fig. 87). They are associated with the sense of
touch, and are most numerous in the hands and feet, where
the tactile sense is delicate. The details of their structure are
obscure. They are elongated, elliptical bodies, lying in the
axis of the papillae, and exhibit transverse or spiral markings.
At their lower extremity they are joined by a medullated nerve-
fibre (or sometimes more than one), the axis-cylinder of which,
losing its coverings, enters the corpuscle, within which it winds

FIG.

FIG. 87.

Tactile corpuscle of Wagner, from
human corium (Bohm and
Davidoff).

End-bulb of Krause, from human
conjunctiva (Dogiel).

about and sends off lateral branches. Some authorities regard
these corpuscles as aggregations of transverse flat tactile cells,
others consider them connective-tissue structures with trans-
verse septa.

End-bulbs or tactile corpuscles of Krause (Fig. 88) : These
are small spherical structures in which medullated fibres ter-
minate, and pertain to the sense of touch. They occur in the
conjunctiva and adjacent portion of the cornea, in the corium

CORPUSCLES OF PACINI.

223

of the glans penis and clitoris (genital corpuscles), in the
vicinity of joints (articular corpuscles), and have been found
in mucous membranes in other situations, as the lips, mouth,
colon. They are enveloped in a delicate fibrous capsule con-
taining nucleated endothelioid cells. Within the capsule is a
core, of uncertain nature, in which the axis-cylinder of the
tributary nerve fibre forms an intricate convolution or divides
into branches.

Corpuscles of Pacini (or Voter) (Fig. 89) : These are oval or

FIG. 89.

Pacinian corpuscle from mesentery of cat (Klein).

ellipsoidal structures, of tactile functions, two or three milli-
metres long and half as broad. They occur in the subcuta-
neous tissue (especially of the palms and soles), joints, peri-
osteum, peritoneum, mesentery (especially near the solar
plexus), and other situations; they are located especially
along the course of nerves. They consist of the terminal axis-
cylinder, surrounded by a cylindrical core, and this again
enveloped in a series of numerous concentric lamellae or cap-
sules containing lymph. The axis-cylinder pursues a straight
course, lying in the long axis of the corpuscle ; sometimes it

224 THE NERVOUS SYSTEM.

forks, or at its distal extremity may end in a bulb or divide
into fibrils. The axis-cylinder is surrounded by a granular
or perhaps multinucleated substance, which forms a cylindri-
cal core or " inner bulb."

The bulk of the Pacinian corpuscle is chiefly made up of a
series of twenty-five to fifty concentric lamellce, which envelop
the core. Each lamella consists of a delicate connective-
tissue membrane lined by endothelioid cells, the nuclei of
which appear prominently in sections. The lamellae are de-
rived, partly at least, from the perineurial sheaths of the
entering nerve-fibre, and they are separated by lymph-spaces
filled with serum.

Taste-terminals : The taste-terminals are associated with
specialized neuro-epithelial structures in the tongue, the "taste-
buds" which are described at page 119. The nerves of taste
end in terminal fibrils which are distributed through the epithe-
lial lining of the mucous membrane in the vicinity of the taste-
buds ; some of the fibrils (intragemmal) ramify through the
taste-buds ; others (intergemmal) are distributed between them.

Olfactory terminals : The olfactory nerve-terminals consist
of fine terminal fibrils distributed in the mucous membrane
lining the upper part of the nasal fossa?, in association with
specialized neuro-epithelial or neural elements, the " olfactory
cells," which are described on page 142.

The Eye.

The eye (Fig. 90) is a highly specialized camera-like organ
associated with the termination of the optic nerve. Its parts
are : the conjunctiva, the sclerotic coat and cornea (tunica
externa), the choroid coat, ciliary body and iris (tunica media
or uveal tract), the aqueous humor, the crystalline lens and sus-
pensory ligament, the vitreous body, the retina (tunica interna),
optic nerve, and certain subsidiary structures.

The conjunctiva is a mucous membrane covering the front
of the eye and inner surface of the eyelids. It consists of a
tunica propria covered with stratified columnar epithelium,
except that over and near the cornea the epithelium is of the
stratified squamous variety and over the cornea there is no
tunica propria.

THE SCLEROTIC.

225

The sclerotic is the outermost tunic of the eye. Its anterior
portion is modified to form the cornea. It is a thick, dense
capsule, made up of lamina? of white fibres, between which are

Iris

FIG. 90.

Cornea

Anterior Chamber

Posterior Chamber
Ciliary Body
Ciliary Processes

Canal of.
Petit

Canal of
Schlemm

BY VITREOUS HUMOUR

Nerve sheath

Nerve

Canal for central
Artery

Horizontal section through eye (Allen).

flattened stellate connective-tissue cells and a few elastic
fibres. Its vascular supply is scanty, but the communicating
pericellular spaces form a network of lymph-passages.

15— Hist.

226 THE NERVOUS SYSTEM.

Between the sclerotic and choroid coats is a layer of loose
fibro-elastic tissue containing irregular pigmented connective-
tissue cells ; the portion of this tissue applied to the sclerotic
is called the lamina fusca, that next to the choroid the lamina
suprachoroidea ; in the midst of this tissue are ample lymph-
spaces (subscleral or perichoroidal) lined with endothelium.
Externally the sclerotic rests in a sort of synovial sac, the
capsule of Tenon.

The cornea is the modified transparent anterior portion of
the sclerotic. It consists of five layers, which are, from before
backward : epithelium, anterior elastic membrane, corneal
substance proper, posterior elastic membrane, and posterior
endothelium.

The epithelial layer covering the cornea anteriorly consists
of a few layers of stratified squamous epithelium, and is the
corneal portion of the conjunctiva; the lowermost cells are
columnar.

The anterior elastic lamina (or " membrane of Bowman") is
a thin, hyaline, apparently homogeneous layer, forming a
basement-membrane for the epithelium.

The substantia cornece propria makes up the main part of
the cornea, and consists of transparent lamina? of white fibres
bound together by cement-substance. Between the lamina?
are numerous stellate connective-tissue cells with anastomosing
branches. These cells and their processes lie in spaces form-
ing a network of passages through which lymph can perco-
late for the nutrition of the cornea, which possesses no blood-
vessels.

Behind the substantia propria is the posterior elastic lamina
(or " membrane of Descemet "), a thin, homogeneous, hyaline
layer like the anterior one. Upon the free posterior surface
of this membrane is a single layer of endothelium-cells, con-
tinuous with those lining the anterior surface of the iris.

The cornea contains plexuses and terminals of nerve-fibrils.
At the junction of the cornea and sclerotic, in the substantia
propria, is a venous or lymph-passage, the canal of Schlemm,
encircling the cornea.

The choroid is the thin, middle vascular tunic of the eye.
Anteriorly it is continuous with the ciliary body and iris.
The outermost layer of the choroid is the lamina supra-

THE CHOROID.

227

choroidea, similar to the lamina fusca of the sclerotic, from
which it is separated by lymph-spaces. Next to this layer is
the main stroma of the choroid, or vascular layer, which con-
sists of an abundance of lymphatics and large bloodvessels
imbedded in fibro-elastic tissue containing numerous pig-
mented stellate connective -tissue cells.

FIG. 91.

Section through ciliary body and tunics of eye at corneo-sclerotic junction (Wal-
deyer). A, epithelium of conjunctiva ; B, tunica propria of conjunctiva; C,
sclerotic; A laminae fusca and suprachoroidea ; E, F, choroid ; G, pars retinae
ciliaris and iridica; H, cornea; /, iris : K. M, radial and meridional portions
of ciliary muscle ; L, circular portion of ciliary muscle ; N, ligamentum pectina-
tum; 0. margin of anterior chamber; 1, anterior elastic lamina of cornea; 2,
posterior elastic lamina and endothelial layer of cornea : 3, spaces of Fontana ;
4, canal of Schlemm ; 5, 6, vessels tributary to canal of Schlemm ; 7, 8, 9, fibrous
bundles of sclerotic cut transversely; 10, origin of meridional ciliary muscle ;
11, 12, bloodvessels.

Next within this is the thin choriooapillary layer, a dense
capillary network. Next to this is a thin, hyaline homo-
geneous vitreous layer (lamina basalis, membrane of Bruch),
the innermost layer of the choroid and separating it from the
retina.

228 THE NERVOUS SYSTEM.

The ciliary body is a thickening of the choroid anteriorly,
at its junction with the cornea, sclerotic, and iris. Its sub-
stance is similar to that of the choroidal stroma, consisting of
vessels imbedded in connective tissue ; the choriocapillary
layer is wanting, the capillaries being more generally dis-
tributed.

Its posterior surface is thrown up into radiating processes,
the ciliary processes, increasing in height toward the iris, at
the periphery of which they abruptly terminate. The vitreous
membrane is continued over the surface of these processes.

Upon the posterior or inner surface of this membrane rests
a layer of pigmented epithelium, and then a single layer of
columnar epithelium ; these two layers are an anterior con-
tinuation of the retina (pars ciliaris retince).

In the substance of the ciliary body is the ciliary muscle,
fasciculi of involuntary muscle arising near the corneo-
sclerotic junction and extending thence radially or meridion-
ally outward and backward, together with some circular
fasciculi.

The ciliary body at the margin of the iris is united to the
corneo-sclerotic junction by fibrous processes, the ligamentum
pectinatum, the interstices of which form the lymph-spaces of
Fontana.

The iris is attached by its peripheral margin to the ciliary
body at the corneo-sclerotic junction. It consists of six layers :
from before backward, endothelium, anterior boundary layer,
stroma, posterior boundary layer, pigment-layer, and limit-
ing membrane.

The endothelium covering the anterior surface of the iris is
continuous with that on the posterior surface of the cornea.

The anterior and posterior boundary layers and stroma of
the iris are continuations of choroidal tissue.

The anterior boundary layer is a loose connective tissue
containing lymphoid cells ; it merges into the stroma.

The stroma, or main portion of the iris consists chiefly of
radiating bloodvessels and circular and radiating fasciculi of
involuntary muscle imbedded in connective tissue. The con-
nective-tissue cells of the stroma and anterior boundary layer
contain pigment in varying amount, to which the color of
the iris is partly due.

THE SUSPENSORY LIGAMENT. 229

The posterior boundary layer is a thin hyaline layer corre-
sponding to the vitreous layer of the choroid.

The pigment-layer is a continuation of the retina (pars
iridica retinae), and consists of densely pigmented epithelium-
cells, fusiform anteriorly, polygonal posteriorly.

The membrana lirnitans iridis is a delicate cuticular mem-
brane covering the pigment-layer posteriorly.

The aqueous humor consists of lymph, containing a few
leukocytes ; it occupies the anterior chamber of the eye, which
is essentially a large lymph-space communicating with the
ocular lymphatics and is lined with endothelium, the same
layer which covers the posterior surface of the cornea and
anterior surface of the iris.

The crystalline lens consists of a mass of epithelioid lens-
fibres covered by a layer of epithelium anteriorly ; the whole
enveloped in a capsule.

The anterior epithelium is a single layer of low columnar
cells covering the anterior surface of the lens beneath the
capsule.

The lens-fibres, composing the bulk of the lens, are long
curved hexagonal fibres cemented together, arranged some-
what concentrically and meridionally. Oval nuclei are pres-
ent near the middle of the fibres at the equator of the lens,
and in all the fibres when young. The lens-fibres are greatly
elongated epithelium-cells, derived from the posterior epithe-
lium of the embryonic lens. At the equator of the lens a
transition from the anterior epithelium into the posterior
epithelial fibres is observable.

The capsule is an elastic cuticular membrane enveloping
the lens.

The suspensory ligament (zone of Zinn, zonula ciliaris) en-
circles and supports the lens, being attached to the capsule of
the latter near the equator. It is a fibrous structure, radially
plicated ; it is connected posteriorly with the hyaloid mem-
brane of the vitreous body, and with the ciliary body and
processes, so that contraction of the ciliary muscle relaxes it
and permits the elastic lens to increase in convexity and re-
fractive powrer. At its union with the lens it splits into two
layers, anterior and posterior, with a lymph -space between
thenx, called the canal of Petit.

230 THE NERVOUS SYSTEM.

The vitreous body fills the large cavity of the eye. It con-
sists of a soft gelatinous substance, scattered about in which
are stellate connective-tissue cells and scanty fibrous elements
— a sort of mucous tissue. It is surrounded by a homogene-
ous membrane, the hyaloid membrane, which separates it from
the retina and lens.

The retina, the inner tunic of the eye, lies between the
choroid and the vitreous. It is divisible into three parts, the
optical, ciliary, and iridic portions ; the two latter being rudi-
mentary anterior portions.

The pars retince iridica covers the posterior surface of the
iris, and consists of densely pigmented epithelium-cells covered
by a limiting membrane.

The pars retince ciliaris covers the posterior surface of the
ciliary body and processes, and consists of layers of pigmented
and columnar epithelium and an internal limiting membrane.

A short distance behind the ciliary body the pars retince
optica or main functional portion of the retina, the retina
proper, begins by an abrupt thickening or fold, the ora serrata.

The retina proper exhibits the following layers, from within
outward (Fig. 92) : internal limiting membrane ; nerve-fibre
layer ; ganglion-cell layer ; inner reticular layer ; inner nuclear
layer ; outer reticular layer ; outer nuclear layer ; external
limiting membrane ; layer of rods and cones, and pigment-
layer.

The elements making up the retina are nervous, neuro-
epithelium, pigmented epithelium, and sustentacular.

Conspicuous among the sustentacular elements are the
radiating fibres of MiQler, specialized neuroglia-cells. Their
inner ends are expanded and by their junction form the so-
called internal limiting membrane of this portion of the retina ;
from these pyramidal ends the cells or fibres, more attenuated,
pass perpendicularly outward through the various layers to
the external limiting membrane, giving off lateral sustentacular
branches and reticula ; in the inner nuclear layer the fibre ex-
hibits a nucleus, and externally the fibres terminate in fine
processes which pierce the external limiting membrane and
lie among the bases of the rods and cones. Other branched
neuroglia-cells lie in the outer reticular layer.

The nerve-fibre layer is made up of non-medullated nerve-

THE INNER EETICULAR LAYER.

231

fibres derived and radiating from the optic nerve and also
connected with the retinal nerve-cells.

The ganglion-cell layer consists of rather scattered large
rounded nerve-cells with numerous branched processes.

FIG. 92.

Diagrammatic section of human retina (Schultze).

The inner reticular (or molecular) layer is a broad non-
nucleated zone formed by a delicate fibrous reticulum derived

232 THE NERVOUS SYSTEM.

from the neuroglia-elements and the processes of neighboring
nerve-cells.

The inner nuclear (or granular) layer is a narrower zone
crowded with nerve-cells having prominent nuclei ; the nuclei
of Miiller's fibres are also in this layer.

The outer reticular (or molecular) layer is a narrow reticu-
lum of neuroglia- fibres and nerve-cell processes.

The outer nuclear (or granular) layer is a broad zone crowded
with the nuclei and the lower portions of the rod and cone cells.

The external limiting membrane is a thin perforated mem-
brane, through the openings of which pass the rod and cone
cells.

The layer of rods and cones is composed of the portions of
the rod and cone cells external to the limiting membrane.
The rod and cone cells are elongated neuro-epithelium cells,
arranged perpendicularly, divided into two zones by the limit-
ing membrane, their nucleated portions occupying the outer
nuclear layer and their terminal portions forming the layer of
rods and cones.

The portion of the rod-visual cells in the nuclear layer is a
slender fibre, the " rod-fibre," with a bulbous expansion con-
taining the transversely banded nucleus. The portion external
to the limiting membrane, or " rod," consists of two segments,
the inner one continuous with the rod-fibre being fusiform,
and granular or fibrillated (especially in its outer part) ; while
the outer segment is a slender cylinder containing rhodopsin
and possessing special staining properties.

The portion of the cone-visual cells outside of the limiting
membrane, or the "cone," also consists of two segments, an
outer part similar to the corresponding portion of the rods ex-
cept that it is shorter, conical, and contains no rhodopsin; and
an inner broad fusiform portion, fibrillated or granular exter-
nally. The portion of the cone-cell within the outer nuclear
zone consists of a slender " cone-fibre" with an expansion,
containing the nucleus, next to the limiting membrane and
uniting with the fusiform segment. The rod-cells consider-
ably outnumber the cone-cells.

The pigment-layer of the retina, lying next to the vitreous
membrane of the choroid, consists of a single layer of hex-
agonal columnar epithelium-cells, with their nuclei next to the

THE EAR. 233

cboroid, and their inner portions, adjoining and between the
rods and cones, studded with pigment-granules.

In the macula lutea the rods are absent and some of the
retinal layers are thickened and pigmented yellow. At the
fovea centralis only the layer of cone-cells is present in full
development, the layers in front of it — i. e., toward the centre
of the globe — being greatly thinned and nearly abolished.

The eyelids (upper) are covered anteriorly with thin skin,
beneath which is areolar subcutaneous tissue containing little
or no fatty tissue. Next to this is a layer of striated muscle,
the orbicularis palpebrarum. Posterior to this is a zone of
loose connective tissue, the fascia palpebr alls, into which the
insertion of the levator palpebra? merges. Posterior to this
and next to the conjunctiva is a dense fibrous plate, the
tarsus, in which are imbedded a number of modified seba-
ceous glands, the Meibomian glands, each consisting of an
elongated series of follicles opening into a duct which dis-
charges at the margin of the lid.

In the upper part of the tarsal plate, especially toward the
nose, are small accessory lachrymal glands. The posterior
surface of the lid is covered by conjunctiva, composed of
stratified columnar epithelium on a tunica propria, which lies
next to the tarsus.

At the margin of the lid is a row of stiff hairs, the eye-
lashes, the follicles of which separate the margin of the
orbicularis palpebrarum from the main portion of the muscle ;
behind the lashes are modified sweat-glands (Moll's glands) ;
and still farther posteriorly are the openings of the Meibomian
glands.

The lachrymal gland is a racemose gland of the serous type,
the saccules of which empty into a number of independent
and separate outlet-ducts. The lachrymal canals are tubes
lined with mucous membrane connecting the conjunctive with
the nasal fossa?.

The Ear.

The ear is a complicated structure associated with the term-
ination of the nerves of hearing, and \vith the sense of
position. It is divided into the external, middle, and internal
ear.

234 THE NERVOUS SYSTEM.

External ear : The auricle consists of a basis of elastic
cartilage covered with subcutaneous tissue and skin — except
the lobule, whose interior is occupied by fibrous tissue.

The outer (cartilaginous) portion of the external auditory
canal is lined with skin, which is very thick and contains
hairs, their sebaceous glands, and ceruminous glands, a modi-
fied form of sweat-gland. This portion of the canal has a
basis of elastic cartilage beneath the subcutaneous tissue.

The inner (bony) portion of the auditory canal is mostly
lined with thin skin containing no glands or hair.

The middle ear (or tympanum) is a cavity filled with air,
communicating with the Eustachian tube anteriorly and the
mastoid sinuses posteriorly, and crossed by a chain of ossicles
connecting the tympanic membrane with the fenestra ovalis.

Its walls are formed by bone, the tympanic membrane, and
the secondary tympanic membrane, all lined with mucous
membrane.

The mucous membrane is thin and closely connected with
the underlying periosteum ; it is reflected over the surface of
the ossicles and mastoid sinuses and is continuous with the
mucous lining of the Eustachian tube. Its superficial layer
consists of low columnar epithelium, in places ciliated, in
other places non-ciliated. Anteriorly are scattered tubular
glands.

The tympanic membrane is made up of an intermediate
fibrous lamina covered externally with skin and internally
with a portion of the mucosa lining the middle ear; the sur-
face epithelium-cells of the latter are low and non-ciliated.

The secondary tympanic membrane closes the fenestra
rotunda, and consists of an intermediate fibrous lamina,
covered externally with mucous membrane (having non-ciliated
low epithelium) continuous with the mucosa of the middle ear,
and internally with endothelium and subendothelial tissue
continuous with that lining the internal ear.

The Eustachian tube is an open canal connecting the middle
ear with the pharynx. Its walls are formed of bone, cartilage
(partly hyaline, partly elastic), and fibrous tissue, lined with
mucous membrane continuous with that of both the middle
ear and pharynx. The surface cells of this mucosa are strati-
fied ciliated epithelium. In its upper portion the mucous

THE UTRICLE AND SACCULE. 235

lining is thin ; in the lower or pharyngeal portion it is thicker,
underlaid with areolar submucous tissue, and contains mucous
glands and lymphoid tissue.

The internal ear (or labyrinth) contains the terminal appa-
ratus of the auditory nerve, and occupies a tortuous bony
cavity (the " bony labyrinth") in the temporal bone.

The bony labyrinth has three divisions — the cochlea, semi-
circular canals, and vestibule, the latter connecting the two
others.

Within the bony labyrinth is a membranous sac, the " mem-
branous labyrinth" containing " endolymph" and correspond-
ing in general to the windings of the bony labyrinth.

The membranous labyrinth is separated from the bony
walls in most places by a peripheral lymph-space, lined with
endothelium and filled with "perilymph."

The bony labyrinth is lined with periosteum, covered in
general with endothelium.

The membranous labyrinth consists of the utricle and
saccule, situated in the vestibule, the membranous semicircular
canals, and the scala media of the cochlea.

The neuro-epithelial terminals of the auditory nerve are
situated on the inner surface of the membranous labyrinth,
and consist of the maculce acusticce of the utricle and saccule,
the cristce acusticce of the ampullae of the semicircular canals,
and the organ of Corti.

The vestibule is a bony chamber connecting the semicircular
canals with the cochlea. It contains the utricle and saccule,
which are separated from the bony walls by the perilymph-
space. This space is in relation with the middle ear by the
fenestra ovalis, which is closed by the base of the stapes.

The utricle and saccule are rounded membranous sacs, com-
municating with each other by a small indirect canal, the
" ductus endolymphaticus." Their walls are formed by a
fibrous membrane lined internally with simple squamous epi-
thelium, altered to columnar in the maculae acustica3 ; exter-
nally they are covered with endothelium. They are connected
with the periosteum of the bony walls by fibrous bands, which
cross the peri lymph-space and convey vessels and nerves.
The utricle opens into the semicircular canals; the saccule
communicates through the small " canalis reuniens" with the

236 THE NERVOUS SYSTEM.

scala media, or cochlear portion of the membranous laby-
rinth.

The utricle and saccule each possesses on its inner surface
a neuro-epithelial terminal, called the macula acustica.

The macula is an area covered with columnar epithelium-
cells of two kinds : (a) " sustentacular" or " fibre-cells," long,
slender cells, between which are situated (6) " hair-cells," pyri-
form cells with filamentary processes or cilia projecting from
their free ends. Terminal nerve-fibrils from the auditory
nerve are in relation with the bases and sides of the hair-cells.
The surface of the macula is covered with a matrix or layer
containing minute calcium-carbonate crystals, or "otoliths."

The semicircular canals, opening from the utricle, are mem-
branous tubes formed of a fibrous membrane lined internally
by simple squamous epithelium (except over the cristas) and
externally with endothelium, and separated from the bony
walls by the perilymph-space. Each membranous canal has
an enlargement or ampulla at one of its junctions with the
utricle, and on the inner surface of each of the three ampulla;
is situated a neuro-epithelial structure called the crista acustica.

These cristce are ridges covered with columnar epithelium-
cells of two kinds, similar to those of the maculae acusticse :
(a) "sustentacular" or " fibre-cells," long, slender columnar
cells, between which are (6) " hair-cells," shorter cells with
long hairs or cilia projecting from their free ends into the
ampulla?. Nerve-fibrils terminate among the hair-cells. There
is no layer of otoliths over the cristaB.

The cochlea consists of three passages, the scala vestibuli,
scala media, and scala tympani, wound spirally two and a
half turns around a central column or "modiolus" (Fig. 93).

The scala media is the cochlear portion of the membranous
labyrinth ; the other two scalse represent the perilymph-spaces.

The scala vestibuli and scala tympani are lined with endo-
thelium, and are separated from each other externally by the
scala media and internally by the "lamina spiralis," a spiral
bony ledge projecting from the modiolus.

The scala vestibuli is the uppermost of the three cochlear
passages, and opens below into the perilymph-space of the
vestibule; at the apex of the cochlea it communicates with
the scala tympani. The lower end of the latter is blind, but

THE SCALA MEDIA.

237

communicates with the middle ear by the fenestra rotunda,
closed by the secondary tympanic membrane.

The scala media (canalis or ductus cochlearis) is the middle
passage of the cochlea ; it ends blindly above, and communi-
cates below with the saccule by the small canalis reuniens.

FIG. 93.

Radial section of portion of cochlea of guinea-pig (Klein), a, scala vestibuli ; 6,
scala tympani : c, scala media ; d, rnembrana tectoria ; h, membrane of Reiss-
ner ; j, organ of Corti, resting on basilar membrane ; k, stria vascularis ; I, liga-
mentum spirale; m, limbus ; n, nerve-fibres in lamina spiralis ; o, spiral gan-
glion ; p, nerve-fibres in modiolus ; s, bony wall.

The upper wall of the scala media, separating it from the
scala vestibuli, is formed by the membrane of Reissner, a very
thin fibrous membrane lined on the vestibular surface with
endothelium, and on the surface within the scala media with
simple squamous epithelium.

238 THE NERVOUS SYSTEM.

The outer wall of the scala media is lined with a single
layer of epithelium-cells, varying from squamous to columnar,
which rest on the ligamentum spirale, a fibrous cushion lying
against the bony walls on the outer side of the cochlea; a
portion of this outer wall (" stria vascularis ") is very
vascular.

The floor or lower wall of the scala media is formed by the
margin or limbus of the lamina spiralis, the basilar membrane,
and columnar and neuro-epithelium (the organ of Corti) rest-
ing on the latter. The margin of the bony spiral lamina is
thickened by the development on its upper surface of a mass
of fibrous tissue, the whole forming the limbus.

The outer projecting aspect of the limbus is hollowed
into a groove, the sulcus spiralis, the upper lip of which
is called the labium vestibulare, the lower lip the labium tym-
panicum.

The labium vestibulare is divided by clefts into fine proc-
esses called the " auditory teeth."

The membrana basilaris is a connective-tissue lamina ex-
tending from the labium tympanicum of the limbus across to
the ligamentum spirale on the outer wall, shutting off' the
scala media from the scala tympani ; it is lined underneath
(within the scala tympani) with endothelium, while its upper
surface is covered with columnar epithelium and the neuro-
epithelium constituting the organ of Corti.

The upper surface of the limbus is lined with simple squam-
ous epithelium continuous with that lining the membrane of
Reissner.

The sulcus spiralis is lined with a layer of columnar epithe-
lium-cells, which extend to the inner hair-cells or inner margin
of the organ of Corti.

The organ of Corti (Fig. 94) : These inner hair-cells
comprise a single row of columnar epithelium-cells, with a
number of filaments or hairs projecting from their free ends ;
they are adjacent to and on the inner side of the pillars of
Corti, their attached ends not extending to the basilar mem-
brane.

The pillars or rods of Corti are two rows of elongated
epithelial elements, the lower ends of which rest on the basilar
membrane some distance apart, and whose upper ends are

THE ORGAN OF CORTI.

239

articulated together, meeting like the rafters of a roof; they
inclose a lymph-space or passage, the "tunnel of Corti,"
which follows the spiral windings of the cochlea.

These pillar-cells, inner and outer, have slender shafts of a
firm substance, with enlarged extremities, and with nuclei and
some ordinary protoplasm at their lower ends.

External to the pillars of Corti are three or four rows of
outer hair-cells, columnar epithelium-cells with hairs projecting
from their exposed ends. They extend from the upper sur-

Fio. 94.

Organ of Corti, human, in cross-section (Retzius).

face of the organ of Corti only about half-way to the basilar
membrane.

The outer hair-cells alternate with and are supported by the
cells of DeiterSj long columnar sustentacular epithelium-cells,
somewhat like the pillar-celis, and with their bases separated
by slight intervals, the "spaces of Nuel."

The upper ends of the pillar-cells and cells of Deiters

240 THE NERVOUS SYSTEM.

exhibit a cuticular structure (the "membrana reticularis "),
with openings for the ends of the hair-cells.

External to the outer hair-cells is a zone of long colum-
nar epithelium-cells (cells of Hensen), which externally be-
come shorter and merge into a zone of low columnar epi-
thelium (cells of Claudius)} the latter occupy the outermost
part of the basilar membrane and are continuous with
the squamous epithelium lining the outer wall of the scala
media.

Attached to the labium vestibulare of the limbus is a soft
structure, the membrana tectoria, which extends outward over
the organ of Corti.

Nerve-fibrils from the cochlear branch of the auditory nerve
terminate among the hair cells of the organ of Corti. The
cochlear nerve lies in the modiolus, and sends branches
laterally into the lamina spiralis, where they are associated
with nerve-cells to form the spiral ganglion; from the
ganglion the nerve-fibres pass out into the organ of Corti
at the labium tympanicum.

PATHOLOGY.

INTRODUCTORY.

Pathology (nado^, disease, and ^oc, discourse) is the science
which treats of animal and vegetable life under abnormal
conditions — i. e., the science of disease. It is that branch
of medicine which considers abnormalities of structure and
function, the causes thereof, and the relation of these changes
to the clinical aspects of disease produced thereby.

Human pathology then includes the study of etiology or the
causes of disease ; morbid anatomy — macroscopical and micro-
scopical ; and morbid or pathological physiology. With these
must always go hand in hand clinical observation, in order
that a true conception may be formed of disease-processes. As
our knowledge of anatomy is more advanced than that of
physiology, so our knowledge of morbid anatomy is more
perfect than that of morbid physiology.

The importance of this branch of medicine cannot be over-
estimated by the student ; it is the one sure basis for diag-
nosis, prognosis, and rational therapeusis. Some of the
greatest additions to medical knowledge have been made by
the study of morbid anatomy in conjunction with clinical
observation. Apoplexy was supposed to be due to the inter-
ruption of certain imaginary spirits till Wepfer showed cere-
bral hemorrhage to be the cause in a large number of cases.
In this manner Bright demonstrated the relation between
certain alterations in the kidneys, and albnminuria and dropsy.
Typhoid and typhus fevers were regarded as identical until
1836, when a post-mortem study of the lesions present proved
the contrary. The mediaeval physician rarely endeavored to
locate the seat of a disease — certainly not beyond assigning
it to one of the larger cavities of the body, i. e., the head,

243

244 INTRODUCTORY.

chest, or abdomen. In fact, but little was added to the teach-
ings of Hippocrates (460 B. c.) and Galen (130-200 A. D.)
until about 1500, when the first post-mortems began to be
made.

During the sixteenth century Vesalius, Sylvius, and their
successors laid the foundation of modern medicine by the
systematic study of anatomy, to which was added by Harvey
and others during the seventeenth century such essential
physiological data as the function of the heart, circulation of
blood, and the mechanism of respiration.

Morgagni (1682-1771) was the first to attempt to localize
a disease-process in a particular organ and wrote the first
great treatise on morbid anatomy. The first illustrated work
on the subject was by Baillie (1799), who drew his inspiration
and material from John Hunter. It was not until the early
part of this century, however, that there was a real beginning
in its study. But there were limitations to gross morbid
anatomy.

Histology received its first impulse from Bichat, to whom
is due also a step in advance in pathology ; he declared that
the ultimate seat of a disease might be a particular tissue
of an organ. Though the microscope had been employed
in the seventeenth century by Leuweenhoeck and Malpighi,
it was as recent as 1847 that the foundation of normal his-
tology was laid by the work of Schleiden on "Vegetable
Pathology/' and later of Schwann on the " Comparison of
the Cellular Structure of Vegetables and Animals."

Modern or cellular pathology dates from the teachings of
Virchow (1858), to whom credit is due, more than to any
other one man, for elevating the study of disease to a place
in the science of biology. The cellular theory of life led
naturally to the cellular theory of disease. A comparison of
the lower forms of animal and vegetable life with the cells
of higher ones convinced Virchow that if the former are in-
dividuals, the latter must be so regarded also. For the axiom
of Harvey, "Omne vivum ex ovo," he substituted the dictum
" Omnis cellula a cellula " ; he applied the histological dis-
coveries of Schleiden and Schwann to pathology and showed
that the essence of disease is the altered cell, — the histological
and vital unit of all organized tissue, — and called attention to

INTRODUCTORY. 245

the minute changes which it undergoes in disease. The cellu-
lar theory has done for pathology what the atomic theory has
for chemistry.

Medical knowledge has been advanced more in recent
years by experimental pathology than by any other method of
investigation. Though Galen is said to have used living
animals for pathological experimentation, the foundation of
these methods and the revival of pathology in general were
due to John Hunter in the latter part of the last century. To
bacteriology, one branch of experimental pathology, we owe
our knowledge of the microbic cause of many of the infec-
tious diseases — the germ-theory, in its practical results having
almost revolutionized medicine and surgery within a quarter
of a century.

Disease is a deterioration in or deviation from the normal
standard called health. Probably all deviations of function
from normal are dependent on some alteration in structure ;
when our present methods fail to discover such anatomical
changes the disease is said to be functional, in contradistinction
to organic disease, in which such alterations can be demon-
strated. There is no sharp line of demarcation between
health and disease, the one passing imperceptibly into the
other.

Heredity plays a most important part in the causation of
disease ; it is not uncommon to see reproduced in a family the
same infirmities or diatheses for many generations — and the ill
results of consanguineous marriage are a matter of common
knowledge.

Susceptibility to various diseases varies greatly in different
individuals— the determining factors being inherited in some
cases and acquired in others, and temporary or permanent in
their duration. The susceptibility of children of tubercular
parents to tuberculosis is observed with great frequency ;
without such inherited tendencies however, during some tem-
porary impairment of health, there may be an acquired
susceptibility to the disease, which, for instance, is especially
common after measles in children — the attack either preparing
a soil particularly inviting to the tubercle bacilli or reducing
the patient's resisting powers to such an extent that they are
not able to cope with the invasion of these micro-organisms

246 INTRODUCTORY.

successfully, as would be the case wer6 they not temporarily
so reduced.

The well-known insusceptibility of the negro to yellow fever
and malaria are examples of the comparative immunity
which a race may enjoy ; and among the lower animals the
same thing is noted of different species — for instance, the frog
is immune against infection with anthrax, while the mouse,
guinea-pig, and many other animals are extremely susceptible.

The comparative insusceptibility of an individual to a
second attack of such diseases as smallpox, scarlet fever, and
measles is an example of acquired immunity. Such immunity
may be conferred artificially, as is witnessed daily in the
practice of vaccinating against smallpox.

Equally striking is the varying susceptibility of an indi-
vidual at various times in his life to the same disease.

Exciting causes are those immediately responsible for the
onset of the disease ; among these may be mentioned trauma,
exposure to heat and cold, poisons, and, by far the most
important of all, animal and, more especially, vegetable
parasites — of which latter bacteria are the most important.

But a discussion of these topics would lead far beyond the
limits assigned us and must be thus dismissed. The study of
bacteriology has grown within a few years to large propor-
tions— and volumes have been written concerning animal
parasites.

Pathology, or pathological anatomy, with which the following
pages are more especially concerned, may be divided for con-
venience into two sections — one, the general aspects of disease-
processes without reference to any individual part ; and the
other, diseases of special organs and systems.

GENERAL PATHOLOGY.

CHAPTER I.

PATHOLOGY OF THE BLOOD AND CIRCULATION.

INFLAMMATION.

Inflammation is undoubtedly the most important and most
common phenomenon in pathology. It is convenient to con-
sider it as an entity rather than a series of morbid phenomena.
Ko subject in medicine is more deserving the student's atten-
tion. It underlies a majority of the diseases to which man is
heir. In all ages its consideration has so dominated the doc-
trines and medical philosophy of the time that it might well
be said to form the basis of the theory and practice of medi-
cine and surgery.

The term " inflammation " was created in the very infancy
of science, indicating that the part involved seemed to
burn — to be inflamed. The cardinal symptoms which are
familiar to all to-day were described two thousand years ago
by Celsus — tumor, rubor, calor, and dolor. The interpretation
of these symptoms and conception of the underlying processes
varied as this or that symptom was considered of the greatest
importance. Humoral doctrines perished with Harvey's
discovery of the circulation of the blood, the advances made
in chemistry, and the systematic study of morbid anatomy.
Since then the study of inflammatory lesions has followed step
by step the progress in the biological sciences.

Definition : We may attempt to define inflammation as the
ensemble of the degenerative and reactionary phenomena oc-
curring in living tissues as the result of mechanical, infectious,
and toxic injuries.

Early experiments : John Hunter, a century ago, was the
first to throw experimental light upon this subject of in-

247

248 PATHOLOGY OF THE BLOOD AND CIRCULATION.

flammation. He froze the ear of a rabbit and then allowed it
to thaw, thus exciting considerable inflammation. The animal
was killed when the process was at its height, the bloodves-
sels of the head injected, and the ears removed and dried.
The unin flamed ear was clear and transparent, and the blood-
vessels easily seen ; the inflamed ear was thick and opaque,
and the arteries much enlarged.

A few years later very numerous indeed are the papers and
monographs describing the changes in the size of the blood-
vessels in an inflamed animal membrane studied under the
microscope. A frog was restrained in a muslin bag and to
the web of the foot — less frequently to its mesentery — or to
the web of the foot of a young duck similarly restrained —
various irritants were applied and the results noted under the
microscope. The increased size in the capillary bloodvessels
was thus observed in the affected area, and further a marked
slowing in the rapidity of the blood-current.

By 184-0 we find the description much more complete.
Addison and others carefully described, in addition, an axial
stream of red blood-cells and a much more slowly moving
peripheral stream in which were found the leukocytes ; and
as the velocity of the circulation became less and less the
great accumulation of the latter along the inner wall of the
vessels was noted. Addison maintained the identity of the
leukocyte and pus-cell ; and even the passage of the leukocytes
through the bloodvessel-walls was described, but failed to at-
tract much attention ; a phenomenon which, since the work
of Cohnheirn, twenty-eight years later, has been studied with
great interest.

The experiments of Cohnheim (1867), though they simply
duplicated the experimental studies of earlier observers on
living animal membranes, were of the greatest importance, for
to him undoubtedly all credit is due for our knowledge of the
migration of the leukocytes, the announcement of which came
as a surprise to all.

Microscopical appearances of inflamed animal membranes :
First stage: Dilatation of vessels; acceleration of blood-current.
When the mesentery of a curarized frog is exposed under the
microscope there is soon noted a dilatation of the arteries and
then of the veins, and to a very much less degree of the capil-

IX FLA MM A TION.

249

laries ; by the end of fifteen or twenty minutes it may be very
decided, most apparent, however, in the arteries. At the same
time there is a marked acceleration of the blood-current, equally
pronounced in arteries, veins, and capillaries. The stage of

POSITIONS OF THE CORPUSCLES IN CIRCULATING BLOOD (EBERTH AND SCHIMMELBUSCH).

FIG. 95.

Appearance when the velocity of the circulation is normal, a, axial column
of corpuscles, both red and white, in such rapid movement that individual
corpuscles cannot be distinguished. Occasionally a white corpuscle is thrown
from the axial mass and appears in the plasmic zone 6.

FIG. 96.

Appearance when the velocity of the circulation is moderately reduced. The zone
b contains numerous leukocytes.

FIG. 97.

lYS---

Appearance when the current of blood is sluggish, a, red corpuscles, still in the
axis ; b, peripheral zone, containing leukocytes, d, and blood-plates, c.

When stasis is fully established the red corpuscles also invade the peripheral zone.
The figures are from observations made on the vessels of a dog's omentum

during life.

acceleration in the blood-current will never last more than one
or two hours, by the end of which time the vessels have be-
come twice their normal diameter.

Second stage: Retardation of blood-current; margination

250 PATHOLOGY OF THE BLOOD AND CIRCULATION.

of the leukocytes. The acceleration of the blood-current,
which may be only transitory, is followed by its progressive
retardation until the vessels are engorged with blood. The
current becomes slower and slower, until finally each individual
red blood-cell can be recognized, and every heart-beat causes
sudden jerks in the flow.

But soon one's attention is fixed upon tine veins. Normally
there are only a few leukocytes to be seen in the periphery of
the current, where they are occasionally driven from the axial
stream of red blood-cells by reason of their lower specific
gravity. But now the number of leukocytes in this peripheral
stream is rapidly increasing. They lag behind the still quite
rapidly moving axial stream of z*ed blood-cells, momentarily
clinging from place to place as they are carried on. This same
tendency is also seen in the capillaries.

In the arteries, with each cardiac diastole a number of leu-
kocytes roll into the peripheral stream, only to be swept back
into the axial stream with the next systole. Finally the inner
surface of the walls of the veins is almost lined by a layer
of leukocytes. This phenomenon of margination was described
by all the earlier observers (Figs. 95, 96, and 97).

Third stage: Diapedesis; interstitial exudation. Margina-
tion is followed, sometimes immediately, sometimes only after
an hour or more, by diapedesis or migration of the leukocytes.
There appears on the external surface of the vessel- wall,
usually on a vein, but sometimes on a capillary, a small but-
ton-like elevation or hump, which little by little grows gradu-
ally larger. This colorless protuberance is seen to undergo
manifold variations in form, to throw out and retract little
finger- like processes; it finally becomes pear-shaped with its
point toward the vessel. The tapering end is gradually en-
larged into a slender pedicle, which finally separates from the
vessel-wall and is retracted into the body of the leukocyte,
for this separated mass of protoplasm is now readily recog-
nized as such. The migration of a leukocyte takes some-
times two hours. The same process is repeated at a large
number of points around the veins and capillaries, so that
by the end of six or eight hours an immense number of
leukocytes have accumulated along the external surface of the
vessel-walls. In the arteries this phenomenon is not noted.

INFLAMMATION, 251

It does occur to a very considerable extent in the capillaries,
and from them emigration of the red corpuscles also takes
place. The leukocytes, as their number increases, do not re-
main in the neighborhood of the vessels from which they
migrated ; while the red globules, which have no power of
amoeboid movement, remain near the vessel from which they
escaped. The migration of the leukocytes continues to such
an extent that, as there is no room for them in the interstices
of the tissue, some reach the free surface of the mesentery.
By the end of six or seven hours the phenomenon is no longer
to be seen.

The serous membrane becomes opaque, due to an exudate of
serum from the bloodvessels, which, by coagulating and en-
tangling in its meshes of fibrin white and red blood-cells,
forms on the surface of the mesentery a sort of a pseudo-
membrane.

These blood- vascular changes have been observed in warm-
blooded animals ; in the wing of a bat and the mesentery of
a rabbit.

The dilatation of the bloodvessels was supposed by Cohn-
heim to be due to the direct injury of the vascular walls by
the trauma, producing chemical and molecular changes of the
greatest importance. These changes in the vascular walls, he
suggested, caused an increased friction of the blood against
the walls, which was supposed to explain the retardation of
the current. A further consequence was the greatly increased
permeability of the vessel-walls, permitting cellular and serous
exudations. We cannot state with certainty the exact cause
of the dilatation of the vessels. That it is not due to vaso-
motor paralysis is shown by the fact that w7hen inflamma-
tion occurs in a part in which the vaso-motor nerves have
been cut the vessels still further dilate.

The slowing of the current is an important factor in the sub-
sequent phenomena of margi nation and diapedesis. This
importance has been experimentally shown by the fact that
artificial acceleration of the current induced by the intra-
venous injection of a 6 per cent, salt solution materially re-
tards the development of these phenomena ; and directly so
in proportion to the degree of this acceleration.

An increased permeability of the vessel walls has been ex-

252 PATHOLOGY OF THE BLOOD AND CIRCULATION.

periraentally demonstrated. A colloid liquid injected into
the vessels traverses their walls even under feeble pressure.
The microscope fails to find any lesion, though it is claimed
by some that an increase in the size of the natural stomata
between the endothelial cells can be made out.

Diapedesis : The demonstration of the migration of leuko-
cytes threw a flood of light upon a very important question —
the source of inflammatory cells. The formation of pus-cells
from connective-tissue cells had never been seen by any one.
It became very evident that at least the great majority were
migrated leukocytes, the resemblance of which to the cells
crowding all inflammatory tissues had been commented upon
by Virchow and other observers many years before. It is
quite probable that their number is greatly augmented by their
multiplication subsequent to migration. As an explanation
of the phenomena of diapedesis two theories mainly are
invoked — the theory of chemotaxis and the theory of phago-
cytosis.

Chemotaxis : It has been known for a number of years that
vegetable plasmodia are attracted by certain substances and
repelled by others : if placed on a surface at a little dis-
tance from a nutrient material, such as a decoction of dead
leaves, the organism moves toward it ; while numerous other
materials, such as a solution of salt and sugar, repel it. To
these phenomena Stahl gave the name positive and negative
trophotropism, for which Pfefler substituted the terms positive
and negative chemotaxis.

A similar chemotactic sensibility has been demonstrated on
the part of the white blood-cells toward various substances.

It has been shown that whereas some materials, such as
quinine, alcohol, chloroform, repel the leukocytes, cultures of
various micro-organisms and proteid substances which can be
separated therefrom attract them. So, it has been suggested,
the leukocytes are attracted by substances formed at the site
of inflammation.

Phagocytosis : Metschnikoff, studying the phenomena of in-
flammation from the standpoint of a biologist, assigns to the
leukocytes the main role. He attempts to elucidate these
complex phenomena by producing them, as far as possible, in
organisms of the most simple structure. We find that unicel-

INFLAMMATION. 253

lular organisms which abound in media surrounding us are
subject to infectious diseases. Infection, which is one of the
most important causes of inflammation, is simply a struggle
between a parasite and its host. We must regard the sum
total of the phenomena of inflammation in human beings as
simply the efforts of nature to offset the effects of an injury.
However simple the phenomena resulting from similar injury
to a unicellular organism — though not constituting inflamma-
tion as we are clinically familiar with it — yet their significance
is the same, and represents a primitive condition of this proc-
ess which undergoes a slow evolution as we ascend in the
animal scale. The power of locomotion and intracellular
digestion is the amoeba's mode of defence.

Metschnikoff says : " If we take a specimen (such as the
yellow plasmodium of Physarum) on our object-glass and
touch its central part with a minute glass rod previously
heated in a flame, we shall produce thermal excitation. Im-
mediately after being touched the central part of the plas-
modium dies and may be clearly distinguished from the living
peripheral portions, which remain motionless as if nothing
has occurred, and are unaffected by the necrosed portion. A
few hours later, however, the plasmodium awakes from its

passive condition and creeps away from the dead part

We thus see the irritating agencies excite in the plasmodium
either a course of events similar to those which accompany the
taking of solid nutriment, or a more or less marked repulsion.
In attempting to produce a reaction which should correspond
to inflammation in the higher animals, we have brought about
the phenomena of attraction or repulsion which occur so fre-
quently in the lives of plasmodia and the inferior animals
generally/7

In embryo sponges there are stages in which the organism is
composed of but two layers, the inner of which is formed of
amoeboid cells, which have the power of englobing various
solid bodies for the purpose of obtaining nutriment and for
defence.

In adult sponges there are three layers — ectoderm, mesoderm,
and entoderm, and now the function of digestion devolves
entirely upon the entoderm, and the amoeboid cells of the
mesodern alone possess a phagocytic power.

251 PATHOLOGY OF THE BLOOD AND CIRCULATION.

"It is apparent that the inflammation of vertebrates, in
which the defending phagocytes emigrate from the vessels to
proceed against offending bodies, is distinguished only quanti-
tatively from the analogous phenomena in invertebrates, and
must, therefore, be regarded as a reaction of the organism
against deleterious agents. We must conclude that the essen-
tial factor, the primum movens of inflammation, consists in a
phagocytic reaction on the part of the animal organism. All
other phenomena are merely accessory, and may be regarded
as a means to facilitate the access of phagocytes to the injured

part The morbid phenomena, properly speaking,

such as the primary lesion or necrosis, as well as the processes
of repair, do not form part of the inflammation, and must not
be confounded with it."

Function and fate of the cellular exudate : The phagocytic
power of leukocytes is well recognized, though all varieties
do not possess this function to the same degree; it devolving
mainly upon the mononuclear and poly nuclear forms, espe-
cially the neutrophiles. The lymphocytes are too young and
have too little extranuclear protoplasm ; nor are the eosino-
philes, the protoplasm of which seems to be undergoing pos-
sibly a retrogressive change, ever seen to englobe red blood-
cells, micro-organisms, or other foreign bodies. Young con-
nective-tissue cells — fibroblasts — and endothelial cells of
bloodvessels and perhaps of lymphatics, especially when
rapidly proliferating, possess this function to a marked de-
gree. Giant-cells are also occasionally phagocytic.

In acute inflammations the neutrophiles are the most active
phagocytes, while in chronic inflammation the large mono-
nuclear leukocytes are the most active. Besides this function
as phagocytes at the site of inflammation, the migrated leuko-
cytes undoubtedly aid in the restoration of the tissue. Ziegler
has long maintained that they develop into connective-tissue
cells, and Metschnikoff states that in the wounded tail of a
batrachian tadpole, if watched for several days, he has seen
the polynuclear cells converted by fusion of their nuclei first
into mononuclear cells and then into typical branched con-
nective-tissue cells. Also in rabbits all the transitional stages
in the conversion of mononuclear leukocytes into epithelioid
and giant-cells have been noted.

VARIATIONS IN THE TYPE OF INFLAMMATION. 255

The function of the serous exudate is quite probably pri-
marily nutritive. Further, it frequently possesses bactericidal
properties, and may be of value in diluting any bacterial
poison present at the site of inflammation. On the other
hand, however, the serum is often an extremely good culture-
medium for various varieties of micro-organisms, so that its
presence may not always result advantageously to the tissue.

Connective-tissue changes : l We have noted that in addition
to their phagocytic function the migrated leukocytes are
capable of playing an important part in repair, by developing
into connective-tissue elements; and further, on the other
hand, that young connective-tissue cells and endothelial cells
of bloodvessels, active proliferative changes in which are
always noted from the very onset of all inflammatory processes,
are markedly phagocytic, though this certainly cannot be
looked upon as their sole function. It would seem that these
are good arguments to extend our conception of inflammation
beyond a simple phagocytic reaction on the part of the animal
organism. There are examples of non-infectious inflamma-
tion where the leukocytic migration is most marked, though
not necessarily phagocytic in its nature, in the sense in which
the term is usually employed.

Synchronous with the blood-vascular alterations at the
outset of inflammation, to which are always added more or
less marked degenerative changes in, or even complete destruc-
tion of, certain of the cellular elements according to the
severity of the irritant, active proliferative changes in the
fixed connective-tissue cells occur, which must be regarded
as a restorative as well as a defensive manifestation, and hence
should be included in our conception of inflammation. We
conclude that inflammation is a purposive reaction, having
for its object the neutralization of the effects of an injury.
In this sense, then, we should include under the head of in-
flammation the phenomena of repair. Undoubtedly their
significance is the same ; but in speaking of inflammation we
have in mind a well-defined clinical picture which here is
absent — the only difference in the phenomena, however, being
one of degree.

Variations in the type of inflammation: In every inflamma-

1 See under head of Repair,

256 PATHOLOGY Of1 THE BLOOD AND CIRCULATION.

tion there are vascular and tissue changes ; but there is a
great variability in the character of inflammations resulting
from differences in the nature of the irritants, their persist-
ence, and in the tissues on which they act.

Irritants may be divided into organized and unorganized,
the former including animal and vegetable parasites, and the
latter mechanical, physical, and chemical influences. The
migrating leukocytes play the more important part when the
irritant is organized. There is a very considerable difference
between a blister in which there is an enormous serous exu-
date containing but few leukocytes, and the slight serous but
enormous cellular exudate produced by pyogenic cocci.

Though this property of inducing the migration of a large
number of leukocytes is well recognized as belonging to cer-
tain micro-organisms, yet the various other factors concerned
in bringing about such a result are not fully understood. In-
tense cold produces an inflammation which is accompanied by
an excessive migration of leukocytes, while the inflammation
produced by heat is accompanied by the emigration of but
very few leukocytes.

Purulent or suppurative inflammation is a variety character-
ized by an excessive migration of polymorphonuclear leuko-
cytes or neutrophiles, and a tendency to liquefaction of affected
areas — i. e.9 by the formation of pus.

Pus is a creamy fluid, of specific gravity about 1030, and
usually alkaline in reaction. If it be allowed to stand, it
separates into two layers. The upper — the liquor puris — is
a clear fluid, yellowish in tint, and resembling blood-serum.
If a drop from the opaque lower layer be examined under
the microscope, one will find suspended therein a great num-
ber of colorless, granular, round cells (see Fig. 98). Their
peculiar horseshoe-shaped nuclei identify them as polymor-
phonuclear leukocytes. If the specimen is from an acute
abscess, in a large number of the cells amo?boid movements
may be noted, especially if examined on a warm stage.

A circumscribed collection of pus in any tissue is known
as an abscess. In addition to the excessive migration of
leukocytes which characterizes purulent inflammation, there
are also a necrosis and liquefaction of the tissue at a given
point, setting free, as it were, the migrated cells within this

PURULENT OR SUPPURATIVE INFLAMMATION. 257

area. In other words, an abscess is simply a liquefied in-
flammatory focus containing a large number of migrated

FIG. 98.

Pus from virulent abscess-formation (Grawitz). The leukocytes show marked ne-
crotic changes, chromolysis. c, c, well-preserved leukocytes; EK, connective-
tissue cells from the neighboring granulations ; z, similar cells necrosed.

leukocytes. In the greater number of cases the liquefaction
of the tissues is a sort of peptonization brought about by fer-

FIG. 98J.

Typhoid ulcer of intestine, second week. A, mucosa and submucosa \B, muscularis ;
C, serous coat ; a, villi ; b, slough, on both sides the broad infiltrated border.
X 12 (Schmaus).

ments the product of bacterial growth. The organisms most
frequently concerned in purulent inflammations are the pyo-
genic staphylococci and streptococci, though the bacillus

17— Hist.

258 PATHOLOGY OF THE BLOOD AND CIRCULATION.

coli, gonococcus, and others occasionally prove pyogenic.
Around the central fluid mass, the pus, there is first a layer
which is soon to become pus, next a zone of inflammation and

FIG. 99.

Parenchymatous nephritis, a, cross-section of a convoluted tubule of the kidney,
the lining epithelium of which is the seat of albuminoid degeneration. The
cells are swollen and their bodies filled with abnormally coarse granules. The
cells to the left are so far disintegrated that the nuclei 'have lost most of their
chromatin. Such cells cannot recover. The cells to the right are less pro-
foundly altered and their nuclei retain sufficient chromatin to stain slightly.
These cells might, perhnps, recover. Other convoluted tubules similarly
affected are represented in oblique section, b, tubule with low, unaffected
epithelium, the nuclei of which stain deeply ; c, round-cell infiltration of the
interstitial tissue in the neighborhood of a Malpighian body, the edge of which
is just above the line c. Section stained with hsematoxylin and eosin.

repair, and then healthy tissue. If such an inflammatory
process occurs on the skin or a mucous membrane, the result-

REPAIR. 259

ing superficial destruction of tissue and loss of substance
constitute an ulcer (see Fig. 98J).

Parenchymatous and interstitial inflammation : In inflamma-
tion of glandular structures, in some instances, the degenera-
tive or proliferative changes in the epithelial cells may be the
more marked, while in others the changes in the interstitial
tissue are the more pronounced, suggesting the term parenchy-
matous for the former and interstitial inflammation for the
latter condition, though they cannot be strictly separated from
each other (see Fig. 99). The same terms are sometimes
employed in a somewhat similar manner in inflammations of
muscle and nerve-tissue.

Productive inflammation (see Fig. 100) is a term occasion-
ally employed when the proliferative changes predominate
over the exudative and degenerative, due either to the nature
of the cause or the extent of the injury. In the viscera, when
the action of an irritant is long continued, such proliferative
activity of the connective-tissue cells may lead to a marked
increase in the sustentacular tissue and a secondary atrophy
of the parenchyma, the term chronic interstititial inflammation
being applied to the condition. Productive inflammation is
well illustrated in the process of repair.

REPAIR.

Healing by first intention : Immediate reunion of an aseptic
wound takes place with scarcely any vascular phenomena.
The prompt juxtaposition of the lips of the wound leaves no
opportunity for an exudation of any great extent. There is
more or less hemorrhage, a small amount of the blood coagu-
lating between the edges of the wound. The filaments of
fibrin which form constitute a sort of scaffolding between the
wounded surfaces.

By the end of twenty-four hours there is evidence of a
superactivity on the part of the injured connective-tissue cells.
They become hypertrophied, their divided prolongations
grow and new ones are protruded, extending along the fibrin
scaffolding, uniting with similar prolongations from other cells,
and thus forming a second scaffolding firmer than the first.
The cells then complete the formation of the cicatrix by the

260 PATHOLOGY OF THE BLOOD AND CIRCULATION.

development of white fibrous and yellow elastic fasciculi.
Though the migration of leukocytes may have been a little
exaggerated, they have taken no active part in the reparative
process.

We might say that the phenomena of inflammation have
been reduced to their simplest terms — complete or partial
destruction of some cells, and a marked functional super-

Chronic interstitial myocarditis, late stage, a, dense fibrous tissue, the final result
of the interstitial inflammation; b, b'-, b", atrophied cardiac muscle-cells;
6', vacuolation of a less atrophic cell ; b", section showing anastomotic branch
joining two cells ; c, partially obliterated bloodvessels.

activity of other connective-tissue elements having for its
object the complete restoration of the injured part.

When the irritant is greater the reparative process pro-
gresses with greater energy.

Healing by second intention : When the surfaces of a wound
are not in apposition or are septic — i. c., infected by bacteria —
the reactionary and reparative phenomena progress with
greater energy because of the greater call upon the reparative
efforts of the organism, or the greater severity of the irritant.

HEALING BY SECOND INTENTION.

261

The wound is said to heal by second intention, and with pus-
formation if it is septic. It is a much slower process, either

FIG. 101.

Healing of an incised wound of the skin united by suture, sixth day. a, epider-
mis ; 6, corium; c, fibrinous, d , hemorrhagic exudate; d, newly formed epithe-
lium, containing numerous karyokinetic figures and showing epithelial plug
projecting into exudate lying beneath ; e, karyokinetic figures at some distance
from line of incision ; /, new connective tissue growing from connective-tissue
spaces and containing cells with karyokinetic figures and bloodvessels with
growing walls ; g, growing new connective tissue with leukocytes ; h, collection
of leukocytes at the lower angle of the wound : i, fibrinoblasts lying inside the
exudate ; k, sebaceous gland ; I, sweat-gland. X 80 (Ziegler).

because the wound must heal in from the sides and bottom or
because tissue-destruction is greater by reason of the injurious

262 PATHOLOGY OF THE BLOOD AND CIRCULATION.

effects of highly noxious chemical products of bacterial
growth on the new proliferating cells.

If we examine an open wound — i. e., one which is healing
by second intention — it will be noted that its surface is covered
by papillary elevations about the size of pin-points. This
is the type of tissue concerned in the repair of all such lesions,
and on account of its appearance is called :

FIG. 102.

Phagocytes from granulations infected with virulent anthrax bacilli (Afanassieff).
a, thread of bacilli, partly within and partly outside of a phagocyte ; both por-
tions show a vacuolation of the bacilli, indicative of their degeneration, d,
thread almost entirely incorporated. Within the cell the incorporated bacilli
lie in vacuoles in the cytoplasm, probably digestive vacuoles. In b and e simi-
lar appearances are presented, c, degenerating thread of bacilli from the fluid
of the granulations. Vacuolation has also taken place in this thread,
showing that the fluids of the granulations have a destructive influence upon
the bacilli.

Granulation-tissue : On microscopical examination one finds
these little elevations to be composed of loops of newly formed
bloodvessels (see Fig. 101) surmounted by a mass of rapidly
proliferating connective-tissue cells and migrated leukocytes.
In addition there may be present certain larger cellular ele-
ments. One variety, the giant-cell, is often many times the
size of a leukocyte, its chief characteristic being a variable
number of nuclei — sometimes as many as one hundred,
usually, however, from five to twenty — irregularly arranged,
sometimes around the periphery of the cell, evenly distributed

GRANULA TION-TISSUE.

263

through the cell-protoplasm or clustered in one spot. These
cells are markedly phagocytic, englobing and removing
bacteria, fragments of the red blood-corpuscles and proto-
plasmic debris generally (see Figs. 102 and 103). Another
variety is large and fusiform with an elongated nucleus.

In the midst of these innumerable cellular elements run
newly formed capillary bloodvessels, the walls of which are
formed of a single layer of cells scarcely differentiated from
those surrounding. The exact method of the formation of
these new bloodvessels is as yet obscure.

As the reparative process progresses the young spherical
connective-tissue cells become more angular and later fusiform.
As they often resemble the epithelial cells of mucous mem-

FIG. 103.

Phagocytes from aseptic granulations (Nikiforoff ). C, phagocytes with pseudopodia ;
E, without pseudopodia; F, proliferating, the daughter-nuclei in the spirem
phase of karyokinesis ; A, B. D, with leukocytes, fragments of tissue, and red
corpuscles in their cytoplasm.

branes they are sometimes called epithelioid. To these cells,
which are especially consecrated to the restoration of connec-
tive tissue, Ziegler applies the term fibroblasts; or chondro-
blasts or osteoblasts if concerned in the regeneration of
cartilage or bone. Still further changes in shape take place,
until finally they become fully developed flat and slender
connective-tissue cells.

Having thus rapidly attained their full development,

264 PATHOLOGY OF THE BLOOD AND CIRCULATION.

evidences of advancing senile degeneration manifest them-
selves with equal rapidity, the numerous new bloodvessels
undergoing atrophy in a similar manner, and thus is formed
the cicatrix.

The formation of new fibrous tissue and regeneration of
other connective tissues occur in much the same manner,
their differentiation occurring secondarily.

THE INFECTIVE GRANULOMATA.

Under this head are usually described a number of infec-
tious diseases all characterized by the formation of tumor-like
nodular masses, microscopically somewhat resembling granu-
lation-tissue in the number and character of their cells, which
have, however, but little tendency to develop into a perma-
nent tissue, and are very liable to undergo degenerative
changes. They are forms of subacute inflammation.

Tuberculosis.

The term tubercle was at one time applied to any nodular
growth. By Laennec it was employed mainly in connection
with the large caseous yellow nodules observed in phthisical
lungs. Baillie (1794) was the first to call attention to the
small, gray, millet-seed-sized tubercles found in the lungs, and
which are now regarded as the anatomical basis of the larger
yellow nodules. But even the smallest " miliary tubercle "
is found microscopically to be made up of still smaller cellular
tubercles.

Though the histology of these cellular tubercles is quite
distinctive, since the discovery of the specific microbic cause
by Koch in 1882, the presence of this bacillus must be re-
garded as the essential characteristic of the disease : this then
is the criterion, whatever the macroscopic or microscopic
character of the lesion (see Figs. 104, 105).

Histological tubercle : The first effect of the presence of the
tubercle bacillus in a tissue is the multiplication of its fixed
connective-tissue cells, resulting in the formation of cells
termed epithelioid on account of the resemblance to epithelial
cells in their abundance of protoplasm. There is also

TUBERCULOSIS. 265

excited a migration of leukocytes, and surrounding the epi-

FIG. 105.

FIG. 104.

Tubercle bacilli in giant-cell (from tuber- Tubercle bacilli (from a colony on
culosis of horse). X 600 (Cheyne). blood-serum), showing the wavy

parallel lines. X 500 (after Koch).

FIG. 106.

A tubercle from a case of tuberculosis of the liver. A multinucleated giant-cell
occupies the centre. Around is an area of commencing caseation and outside
this a zone consisting principally of fibroblasts, and, to a less extent, of leuko-
cytes. The leukocytes are most numerous on the side where caseation is
most advanced. X 250.

thelioid cells we find a layer of smaller lymphoid cells, both
often being supported by a fine connective-tissue reticu-

266 PATHOLOGY OF THE BLOOD AND CIRCULATION.

him. Such an arrangement of epithelioid and lymphoid
cells, with often a large multi nucleated giant-cell in their
centre, constitutes the typical histological tubercle (see Fig.
106).

The structure of these tubercles, however, varies consider-
ably ; in some instances the leukocytic migration is so great
as almost to hide the epithelioid cells. If properly stained, the
tubercle bacillus may be found between the epithelioid cells
first formed ; later they are more numerous, many being
within the cells, especially- within the giant-cells.

The giant-cell was at one time supposed to be typical of
tuberculosis, but it is now known to be frequently found in
other chronic inflammatory processes, and in some tumor-
formations, though neither so abundant nor so conspicuous.
They often have as many as fifteen to twenty nuclei arranged'
around the periphery of the cell or at either of its poles. By
some observers the giant-cells are supposed to result from
the rapid multiplication of the nuclei of the epithelioid cells
without division of the cell-protoplasm ; according to Metsch-
nikoif and others, they result from the running together of
the phagocytic leukocytes and epithelioid cells, combining, as
it were, for a common weal.

Caseation is a most characteristic change affecting the tuber-
cle. It consists in the transformation of its centre, often, in
fact, of the whole tubercle — depending on the abundance and
virulence of the bacteria — into a structureless, opaque, and
granular material, macroscopically resembling cheese. In
part this is due to toxins resulting from the growth of the
tubercle bacilli ; and in part is due to the entire absence of
blood-supply, which can be demonstrated in properly injected
specimens, the capillaries being traceable to the margin of the
tubercle only.

Fibroid transformation : When the inflammatory process is
very chronic, and the bacilli few in number, in place of a
necrotic and destructive process — caseation — the tissues seem
to gain the upper hand, and by the active proliferation and
development of the connective-tissue cells a new fibrous tissue
is formed and thus the disease is limited ; the tubercle is said
to have undergone a fibroid change, and is replaced by scar-
tissue.

FEVER.

267

FIG. 107.

Syphilis.

The lesion which places syphilis among the infective granu-
lomata is the gumma, which occurs in the late or tertiary stage
of the disease.

Though the cause of the disease is not definitely determined,
no one doubts the living nature of the contagium.

The gumma occurs in almost all the tissues of the body,
most frequently, however, in the skin and subcutaneous cellu-
lar tissue ; in bone (tibia, sternum, and skull) ; in the brain
and its membranes (less frequently in the spinal cord) ; and in
the liver, kidneys, and lungs. It presents as a firm yellowish
white nodular mass varying in size from that of a hemp-seed
to that of an apple. On section it
has a gelatinous or gummy appear-
ance. The centre is often yellow
and cheesy from the necrosis it is
prone to undergo. If the nodule
is superficially situated, this necrotic
softening frequently results in the
formation of deep excavated ulcers.

Microscopically the gumma is
composed of migrated leukocytes
and proliferating connective-tissue
cells of various forms. Epithelioid
and giant-cells are less frequently
seen than in tuberculosis. If casea-
tion has begun, in the centre is
found an opaque, homogeneous, and
granular material. At the periphery there is a vascular
newly-forming connective tissue (Fig. 107).

Leprosy, glanders, actinomycosis, and rhinoscleroma are also
characterized by the formation of nodular masses of granula-
tion-like tissue.

FEVER.

Accompanying inflammation there is often very consider-
able constitutional disturbance. The body-temperature may
be elevated ; the pulse and respirations accelerated ; glandular
secretions, altered ; metabolism disturbed ; definite anatomical

Gummy growth from liver, a,
central portions of growth,
consisting of granular debris ;
6, peripheral granulation-tis-
sue ; r, a bloodvessel. X 100
(Cornil and Ranvier).

268 PATHOLOGY OF THE BLOOD AND PECULATION.

changes in various tissues likewise accompanying these phe-
nomena— all of which are included in the clinical term fever.

Rise of body-temperature is the most essential phenomenon
to the existence of fever.

The normal constant temperature of the body depends on
an equilibrium between the processes of heat-production and
heat-dissipation, which is maintained through the influence
of the nervous system ; the exact nature of this mechanism,
however, is not yet fully understood. In fever this equilib-
rium is disturbed, so that the processes of heat-dissipation
and heat-production do not bear a normal relation to each
other.

Etiology : Clinically fever has been observed to follow con-
siderable extravasations of blood ; experimentally it occurs
after transfusion of blood from one animal to another and
also after intraperitoneal injections of blood.

The demonstration of the fibrin-ferment as the pyogenic
substance capable of exciting such a rise of temperature
suggested the investigation of other ferments, and it was
found that the intravenous injection of pepsin, trypsin, and
papoid produced a well-defined fever. This type of fever
corresponds to that observed by surgeons after extensive
aseptic wounds, as a subcutaneous fracture, the pyogenic
material resulting from the disintegration of the injured
tissues.

Most morbid processes with which fever is associated are
due to micro-organisms, and it is consequently quite natural to
turn to these elementary forms of vegetable life in endeavor-
ing to elucidate this subject. Early investigators, less than
fifty years ago, demonstrated that injections of putrefactive
materials into the blood of animals were capable of producing
marked febrile reactions, and a knowledge of the part played
by micro-organisms in the production of putrefaction made
quite evident the importance of their rdle in fever.

In 1863 Davaine described a rod- shaped organism in the
blood of animals sick with splenic fever, and found that in a
healthy animal, if inoculated with the blood of an animal so
affected, the disease was reproduced. Subsequently Pasteur
showed that if these organisms were removed by filtration
through earthen cylinders, though the disease could not then

THE CIRCULATORY APPARATUS. 269

be reproduced by inoculation, there resulted a febrile reaction,
which could only be attributed to chemical poisons — called
ptomains or toxins — the result of the growth of the bacteria.

These chemical substances may be the product of organisms
which are not capable of existing in the living body, but only
in dead vegetable or animal tissues — i. e., saprophytic bacteria,
to which class belong the poisonous alkaloids which have
been isolated from putrefying fish, meat, sausage, cheese, etc.
But of far greater clinical importance in the etiology of
fever are the products of pathogenic bacteria.

Undoubtedly febrile rise of temperature may be produced
by other agencies, such as fear and affections of the nervous
system ; but here grave functional and anatomical disturb-
ances are entirely absent.

The significance of fever is not known, though modern ex-
perimental evidence supports the theory that it is a conserva-
tive effort on the part of nature to combat the noxious sub-
stances which give rise to it. In animals rendered hyperther-
mic by external heat or cerebral puncture and inoculated with
various organisms — pneumococcus and others — the increase
in body-temperature seemed to exert a most favorable influ-
ence on the course of the infection.

The anatomical changes in fever, due to the increased tem-
perature alone, are few. It is difficult to separate the results
produced by the high temperature from those produced by its
exciting cause. Cloudy swelling and fatty degeneration of the
heart, liver, and kidneys, are probably in part due to the fever
itself, though in part undoubtedly to toxic substances circu-
lating in the blood.

THE CIRCULATORY APPARATUS.

Hyperaemia is an increase in the amount of blood in a part :
and is either actual, due to an increase of the flow to the
part ; or passive, due to an obstruction of the outflow.

Active hyperaBmia : Blushing is a physiological example.
Pathologically it is hardly met except associated with some of
the phenomena characteristic of inflammation. A variety
due to vaso-motor paralysis, as seen in experimental section of
the cervical sympathetic in animals, is occasionally met with
clinically, as after gunshot-wound of the same nerve.

270 PATHOLOGY OF THE BLOOD AND CIRCULATION.

Passive hypersemia is produced locally by thickening of
venous walls, external pressure on the veins of a part by a
tumor, gravid uterus, etc. Cardiac weakness produces a gene-
ral venous congestion finally, if severe enough, of all the tis-
sues of the body.

The consequences of venous congestion are more important
than those of active congestion — the blood-serum transudes in
greater quantities than can be removed by the lymphatics, and
the tissues become cedematous and swollen. In the internal
organs there may result pressure-atrophy of the true paren-
chyma-cells and an increase of the connective-tissue elements.

FIG. 108.

Section of white thrombus containing few leukocytes, a, granular masses ; &, granu-
lar threads of fibrin arranged in a network ; c. parallel arranged threads of fibrin.
X 200 (Zeigler).

Local anaemia or ischaemia : This occurs where there is inter-
ference with the blood-supply of a tissue, and results in atrophy
or some degenerative change, or if long continued in necrosis.
It is produced by thrombosis or embolism, atheroma of the
vessel-walls, arterial spasm, or external pressure.

Thrombosis is the coagulation of blood within the heart or
bloodvessels during life.

The appearance and structure of a thrombus depend on the
rapidity with which it is formed ; if slowly, it is composed of

EMBOLISM. 271

layers of fibrin containing blood- plates and leukocytes in its
meshes and is of a grayish-white color ; if rapidly, as the result
of the almost complete stoppage of the circulation, it is com-
posed of fibrin and all the elements of the blood, is soft and
red, resembling a post-mortem clot (Fig. 108).

The cause of thrombosis is found either in alterations in
structure of the vessel-walls, in the composition of the blood
or the rapidity of its flow. If the circulation is arrested
at any point, coagulation ensues as the result of the altered
nutrition of the vessel-wall, producing structural changes
incompatible with preservation of the normal fluidity of the
blood. Inflammatory and degenerative changes in the vas-
cular walls, as well as alterations in the composition of the
blood, for instance after a prolonged illness like typhoid fever,
favor the same result.

The fate of a thrombus may be organization, calcification
forming phleboliths, or fatty degeneration and liquefaction.

Embolism is the process of plugging or stopping up of a
bloodvessel by foreign bodies of various description, carried
in the blood-stream and too large to pass through the vessel
at that point.

The plug or embolus may be a portion of a thrombus ; of
a diseased heart-valve or of a tumor; masses of bacteria
and other parasites, and also pigment, as in malaria ; parti-
cles of fat ; and in wounds of large veins, air, which may
have gained entrance (Fig. 109). Its point of lodgement
depends on its source ; if from the systemic veins, it will be
arrested by branches of the pulmonary artery ; if from the
pulmonary veins or left side of heart, it will occlude some
systemic artery, most frequently in the spleen, kidneys, or
brain ; if from tributaries of the portal vein, it will be
arrested by branches of that vein within the liver. If the
obstructed artery is terminal — i. e., has no free anastomoses —
an infarct is the result.

Infarcts may be anemic or hemorrhagic. The circulation
beyond the embolus is arrested — a wedge-shaped anaemic area
is produced in which later occur coagulative necrosis and
caseation, the degenerated tissue being finally absorbed.

In some cases, however, the affected wedge-shaped area is

272 PATHOLOGY OF THE BLOOD AND CIRCULATION.

engorged with extravasated blood supposed possibly to be
due to a back flow from the veins, in which case the final
remaining scar is pigmented (Fig. 110).

(Edema: Normally a certain amount of fluid transudes
from the capillary bloodvessels into the interstices of con-
nective tissues and the various serous cavities of the body ;
when the amount of this fluid is increased or its removal by

FIG. 109.

A thrombus in the saphenous vein,
showing the projection of the
conical end of the thrombus into
the femoral vessel. S, saphenous
vein; T, thrombus; C, conical
end projecting into femoral vein.
At v, v, opposite the valves, the
thrombus is softened (Virchow).

Diagram of a hemorrhagic infarct. a, artery
obliterated by an embolus (e) ; v, vein filled
with a secondary thrombus (th); I, centre
of infarct which is becoming disintegrated ;
2, area of extravasation ; 3. area of col-
lateral hypersemia (O. Weber).

the veins and lymphatics is lessened the condition is known
as oedema or dropsy. The increased transudation may be
caused by arterial or venous hypersemia, hydrsemic states of
the blood, and possibly by alterations in the walls of the
bloodvessels.

Obstruction of the lymphatic circulation is never a power-
ful factor in the production of dropsy ; but venous obstruction
is a most important mechanical cause.

Clinically the chief varieties of cedema are cardiac, renal,
cachectic, and angioneurotic. Cardiac dropsy is an example
of increased transudation from passive hypersemia, due to the

(EDEMA. 273

inability of the heart to maintain the normal force of the cir-
culation. Renal dropsy results from alterations in the blood
as a consequence of its loss of albumin and possibly also
from degenerative changes in the vascular walls. Cachectic
oedema is associated with almost any condition of impaired
health accompanied by anaemia. Localized cedemas are some-
times associated with lesions of the nervous system, as those
attending neuritis, neuralgia, and occasionally hemiplegia.

18-Hist.

CHAPTER II.

PATHOLOGY OF NUTRITION.

ALL pathological processes are primarily nutritive ; but
the term is usually restricted to necrosis, the degenerations
and infiltrations, hypertrophy, atrophy, and tumors.

Local Death.

Necrosis is a local death of simple cells or groups of cells,
in contradistinction to general or somatic death. It is due to
mechanical, chemical, and thermic injuries ; interference with
the blood-supply ; and to lesions of the central nervous sys-
tem— i. e., trophic disturbances.

The mechanical causes of necrosis are numerous, such as
the crushing of a finger by violence. External pressure, as
from bandages or splints on bony prominences, may cause
necrosis, as may also tension, or pressure from within, pro-
duced by inflammatory exudates. It is often difficult to dis-
tinguish between the direct injurious effect of mechanical,
chemical, or thermic trauma on the tissue-cells and their
indirect effect through circulatory disturbances, as the blood
also undergoes changes resulting in coagulation and stasis in
the capillaries. A temperature of 50° to 68° C., if continued
for any length of time, causes necrosis and higher temperatures
more quickly.

Obstruction of the circulation by a thrombus, embolus, or
atheroma of the vessel-walls produces necrosis. A number of
these causes may act together. If the vitality of a tissue has
been reduced by long-continued passive hypersemia, for exam-
ple as the result of uncompensated valvular disease of the heart,
it succumbs much more rapidly. A slight injury may suffice
in the aged or in conditions like typhoid fever, where the vital
forces are greatly depressed. In senile gangrene, to the
lowered vitality of the tissue are added a weak heart and
274

NECROSIS.

275

atheromatous vessels. In the so-called neuropathic necroses
occurring in diseases of the nervous system an important part
is undoubtedly played by trauma and circulatory disturbances.
Under the microscope it is noted that the cell-nucleus loses
its affinity for nuclear dyes — " chromolysis" — or the chroma-
toplastic substances are broken up into fragments — " karyo-
lysis" — and the nucleus finally disintegrates and disappears, the
cell-protoplasm becoming homogeneous in appearance. There

FIG. 111.

Fat-necrosis. The abrupt transition from the healthy cells on the left to the ne-
crosed cells on the right is well marked. The contents of the affected cells are
finely granular. (From a specimen by Dr. Rolleston.)

is always more or less inflammatory reaction in the surround-
ing tissues. Complete regeneration or cicatrization, calcifica-
tion, or cystic formation may follow.

Several varieties of necrosis are usually described : Coagala-
tion-necrosis is a variety in which there is coagulation of the
fluids normally present — lymph — or of inflammatory exudates,
and the cellular protoplasm of the tissue. Fibrin is deposited
in the form of granules or fine fibrillae ; the cells lose their
nuclei and their protoplasm becomes granular. The necessary
ferment to produce this coagulation is derived either from the
degenerating and disintegrating cells or from bacterial prod-

276 PATHOLOGY OF NUTRITION.

ucts. Macroscopieally the affected area is pale, opaque, waxy,
and, later, gray in appearance. On mucous surfaces a false
membrane is formed, as seen in diphtheria.

In liquefaction-necrosis there is a kind of peptonization of
the tissue-elements, which break down and become fluid, the
active agent being some bacterial or non-bacterial ferment.

The term caseation is used to describe a degenerative change
where the tissue macroscopically has the appearance of hard
or soft cheese, and is most frequently seen in connection with
tubercular and syphilitic inflammations. Microscopically one
finds simply a fine granular debris.

Fat-necrosis is a variety which affects fatty connective
tissues. It is most frequently noted in the abdominal cavity
in the subperitoneal fat, and generally is associated with
some pathological change in the pancreas. It is character-
ized by the formation of opaque, white areas about the size
of a pea. Microscopically the cell-contents are crystalline,
opaque, or granular (Fig. 111).

Gangrene is the death of tissue en masse. There are two
varieties, dry or mummification and moist or sphacelus. The
former occurs when the part is so situated that rapid evapora-
tion of the fluids present takes place, especially when the
necrosis has been caused by interference with the blood-supply.
The latter occurs where evaporation is hindered and where
the blood reaching the part cannot escape owing to venous
obstruction. The presence of moisture favors the multiplica-
tion of micro-organisms, resulting in putrefactive changes, the
tissue becoming dark brown or a mottled greenish-black in
color (due to disorganized blood-pigment), and distended with
gases produced by the organisms.

The Infiltrations and Degenerations.

Though theoretically there is a difference between a degene-
ration and an infiltration — the former indicating a conversion
of the cell-protoplasm into a less highly organized substance,
rendering it less suited for the performance of its functions,
while in the latter there is a substitution or deposit of some
new substance in the cell — practically it is often difficult to
distinguish between the two.

FATTY INFILTRATION.

277

Fatty infiltration may be a physiological or a pathological
process. It occurs physiologically under the skin, between
muscles and surrounding organs ; pathologically in abnormal
places, as between individual muscle- fib res, and in normal
situations in great excess, as in general obesity. It is due
to either the over-production of fat or its deficient consump-
tion. Fatty infiltration of the liver may be produced experi-
mentally in the lower animals by an excess of fatty food and
restriction of oxidation by preventing muscular movement.
In phthisis, cancer, and severe anaemias the explanation seems
to be found in lessened oxidation. In chronic alcoholism the
change often occurs, the alcohol being oxidized in place of the
fat.

The fat-drops are larger than in fatty degeneration, and are
found either between the tissue-elements or within the cells,

FIG. 112.

Fatty infiltration of muscle from a case of stiffening of the ankle by an epithelioma
of the skin over it. The muscular fibres are narrowed, and adipose tissue ap-
pears between them. X 80 (Coats).

the nucleus and protoplasm being pushed one side until the
cell is like a vesicle filled with fat (Fig. 112). The liver
is frequently affected in advanced phthisis. On section oil
accumulates on the knife or may be scraped from the cut
surface. The affected organ is enlarged, heavy but of less
specific gravity, soft, less elastic and doughy, and of a light
yellow color, or mottled, if the change is not uniform through-
out. In the liver the change is particularly noted in the
periphery of the acini, giving them a pale yellow margin.

278 PATHOLOGY OF NUTRITION.

In fatty infiltration of the heart the muscle-fibres are not
necessarily affected, and consequently there is little or no func-
tional impairment, though by interfering with the local blood-
supply the condition may become one of fatty degeneration.

Fatty degeneration is caused by local interference with the
blood-supply, anaemias, and high temperature. Poisons such
as mercury, arsenic, lead, phosphorus, ether, chloroform, and,
of still greater interest clinically, the toxins of micro-organ-
isms are frequent causes. The cell is shrunken, not swollen,
its outline irregular, and the nucleus destroyed. The oil-drops
are smaller and do not tend to run together as in fatty infiltra-
tion, appearing in the cell first as small shining granules near
the nucleus. There is a gradual liquefaction of the cells, end-
ing in their death.

Any tissue in the body, with the exception, in the blood,
of the red globules, may be affected ; but the parenchyma-
cells of the liver, kidney, heart, and central nervous system
most often — the interstitial tissue being possibly later affected.

The fat-drops are distinguished chemically by their insolu-
bility in acetic acid and weak solutions of sodium and potas-
sium hydroxide ; and by their solubility in alcohol, ether, and
chloroform, and by staining black with osmic acid. Fine needles
in rosettes, sheaves of margaric acid, and rhombic plates of
cholesterin are often found.

The organ affected is pale yellow or mottled, very anaemic,
and feels greasy and soft.

Amyloid, lardaceous, or waxy degeneration is a very fre-
quent retrograde change and next to fatty degeneration is the
most common. It signifies the presence in the tissue of a
colorless, firm, translucent, homogeneous, inelastic material of
about the consistency of wax or solidified lard, to which, on
account of its behavior toward iodine, the term " starch-like"
has been given ; though we now know that it is not a carbo-
hydrate, but a nitrogenous compound (Fig. 113). If a solu-
tion of iodine and iodide of potassum (LugoPs) be applied to the
freshly cut surface of an affected area, there results a mahogany-
brown coloring, the surrounding normal tissue being stained a
canary-yellow. The addition of a 1 per cent, solution of sulphu-
ric acid gives the amyloid material a bluish color. For micro-
scopical sections a much more satisfactory staining reaction is

AMYLOID, LARDACEOUS, OR WAXY DEGENERATION. 279

found on the addition of methyl- or gentian-violet, producing
a beautiful rose-pink, while the normal tissue stains blue.

The changes are frequently so extensive in all the organs
in the body and the resulting symptoms so numerous that it
is often referred to as lardaceous disease. The organs most

FIG. 113.

Amyloid infiltration in the liver (Thorna). a, lumen of an intralobular capillary,
surrounded by the endothelial wall of the vessel ; b, amyloid substance imme-
diately beneath the endothelium ; c. epithelial cells of the hepatic parenchyma,
some of which show a fatty infiltration.

frequently affected however are the liver, kidney, spleen,
lymphatic glands, intestinal tract and suprarenal capsules.
The changes begin in the inner coat of the smaller capillaries,
and later affect the cells and interstitial substance of the sur-
rounding tissue, extending along the course of the blood-
vessels. If extensively infiltrated, the organ is increased in
size ; is pale, firm, and glistening in appearance. The change
may be quite extensive and yet only noted on microscopical
examination. The parenchyma-cells of the organ swell and
become less angular.

280

PATHOLOGY OF NUTRITION.

The function of the part is impaired by reason of the inter-
ference with the blood-supply and displacement of the proper
tissue-elements. The spleen is usually the earliest organ
involved, beginning in the Malpighian follicles, which become
large, pale and translucent; and resemble grains of sago — hence
the term sago-spleen.

The condition occurs most frequently in connection with
long-continued suppurative processes ; with syphilis and tuber-
culosis ; and not so frequently with other cachexias — cancer,
leukaemia, dysentery, and malaria, and in a few instances with-
out any apparent cause.

Colloid, mucoid, and hyaline degenerations are all closely
allied and but little understood.

a. Colloid: The prototype of this variety is the colloid
material of the thyroid gland (Fig. 114), somewhat similar

FIG. 114.

Section of thyroid gland, showing colloid degeneration, a, colloid ; b, secreting
cells with granules ( after Pozzi).

in appearance to mucus, but firmer. The change affects mainly
epithelial cells and is most often seen in cystic goitre and in
new growths — e. g., colloid cancer — giving rise to a gelatinous
appearance. In ovarian cysts the loculi are sometimes filled
with colloid masses.

b. Mucoid : The physiological type of this change is found

CLOUDY SWELLING.

281

in the mucous secretions of many glands. The change affects
both epithelial and connective-tissue structures, but the latter
is of the greater importance
pathologically. The affected
area has a translucent, gelati-
nous, and swollen appearance.

The most remarkable condi-
tion in which it is found is in
what is known as myxcedema,
the chief clinical characteristic
of which is a peculiar swelling
of the skin and subcutaneous
connective tissue, which differs
from ordinary anasarca in not
pitting on pressure.

c. Hyaline degeneration is
very closely allied to amyloid.
It occurs in connective tissue
and the walls of bloodvessels.
The material has a glistening
waxy appearance but is less
translucent than amyloid, the
staining reactions of which are
also absent.

Cloudy swelling, parenchyma-
tous or granular degeneration,
are terms used to describe a re-
trograde change in which the
elements affected, especially epi-
thelial and muscle cells, are
swollen and cloudy and filled
with minute albuminous gran-
ules. The outline of the cell
becomes indistinct and distorted,
the nucleus however remaining
often but little altered. These
granules are insoluble in ether,
but soluble in dilute acids and
caustic potash. The whole organ is swollen, less translucent,
dull grayish, cloudy, and anaemic — looking as if it had been

Calcareous infiltration of cardiac mus-
cle (Langerhans). a, degenerated
cardiac muscle; 6, muscular fibres
impregnated with lime-salts. The
specimen was taken from a case of
chronic lead-poisoning. The cells
which are the seat of the calcareous
infiltration must have been dead for
a considerable time before the death
of the individual.

282 PATHOLOGY OF NUTRITION.

boiled. The change may occur in any organ in the body, but
is most frequent in the liver, kidney, heart-muscle, and mucous
membrane of the gastro-intestinal tract. It occurs in all
inflammations, in acute infectious diseases, fever, after burns;
and in poisoning from phosphorus, arsenic, and mineral acids.
The cells either soon recover or the process quickly passes on
to fatty degeneration.

Calcareous infiltration, or calcification, is the impregnation of
tissues with the salts of lime in the form of the insoluble
carbonate and phosphate. All parts are alike susceptible,
both the cells and intercellular substance, though the latter to

FIG. 116.

Melanotic alveolar sarcoma of the skin, a, mononuclear ; a', polynuclear sarcoma-
cells with epithelial character ; b, pigment-cells ; c, stroma with bloodvessels
and pigment. X 300 (Ziegler).

the greater degree. The reason of this deposit is not clear,
but it is always connected with a lowered state of nutrition.
The tissue appears dusted with little fine granules, which in
the earliest stage might be mistaken for fat ; but they dissolve
on the addition of hydrochloric acid — and with effervescence
if the carbonate is present (Fig. 115).

PIGMENTARY INFILTRATION. 283

These minute refractive granules enlarge and extend, and so
form dark, opaque, granular patches — white, grayish, or yel-
low in color rnacroscopically. Physiologically the condition
occurs in the pineal gland, choroid plexus, in cartilage in old
age, and notably in the development of bone. The most
frequent pathological sites are the valves of the heart, arterial
walls, caseous lymph-glands, and in myoma uteri when the
blood-supply is poor. It may be noted in necrotic tubercular
foci and infarcts.

Pigmentary infiltration, or abnormal pigmentations, depend
on both intrinsic and extrinsic sources of supply, the former
being either hsematogenous or non-hsematogenous.

1. Intrinsic: a. Hsematogenous. There are twro varieties
of pigment derived from haemoglobin when red blood-cells are
destroyed : hsemosiderin, which contains iron, and hsematoidin,
which does not.

Hsemosiderin gives the characteristic chemical reactions
of iron, and occurs in minute granules in the liver-cells in

FIG. 117.

Pigmentation of the lung (from a woman, set. sixty-five, with slight emphysema),
showing the situation of the pigment in the thickened alveolar walls and around
the bloodvessel, v. The walls of the latter are also thickened and its lumen
diminished. X 75 (Green).

pernicious ana?mia; and is found also in the spleen, renal
epithelium, and medulla of bone in this disease, in leuka?mia,
malaria, severe cachexias, in poisons, and septic processes.

284 PATHOLOGY OF NUTRITION.

Ha3matoidin is found in rhombic crystals or granular in old
blood-clots, free or within leukocytes and other cells.

b. Of non-hsematogenous pigments, melanin is the most
important. It is elaborated by living cells, and contains no
iron. Granules of melanin vary in color from yellow to black.
It is noted, among other instances, in melanotic sarcoma (Fig.
116).

2. Extrinsic : Extrinsic sources of pigment are very numer-
ous, the material being absorbed either through the lungs or
gastro-intestinal tract. Carbon is one of the most common
varieties of extrinsic pigment. When coal-dust is inhaled it
gives rise to deposits of pigment in the lungs, the condition
being known as coal-miners' lung, or anthracosis (Fig. 117).
Siderosis is similarly produced by the inhalation of fine parti-
cles of iron, the lungs becoming rusty in color. In chalicosis,
stonemasons7 lung, the particles are white and the lung con-
sequently abnormally pale.

In argyria silver is absorbed from the gastro-intestinal
tract and afterward deposited in the tissues as an albuminate.
The condition was more often seen when silver was popular
in the treatment of epilepsy and other diseases of the nervous
system.

Atrophy.

The term atrophy means literally want of food. The af-
fected organ undergoes a more or less uniform reduction in size
and weight. It may be congenital — agenesia — or acquired.
In true atrophy there is a decrease only in the size of the cells
of the tissue, their number remaining normal. A decrease in
the number of cells is sometimes spoken of as aplasia, or
more generally as numerical atrophy. Hypoplasia is a failure
of the cells to reach their natural size.

The condition is seen physiologically in the thy m us gland
in the second year of life, in the generative organs at the
climacteric, and in the general atrophy of old age.

Pathologically deficient blood-supply, if long enough con-
tinned but not too severe, is an important cause. Under this
head would come pressure-atrophy, — e. g., the absorption of
the bodies of dorsal vertebrae by an aortic aneurism — and

HYPERTROPHY. 285

also atrophies from disease, as, for example, the gut below a
lumbar colotomy, which becomes the size of one's little finger.
There are many instances of atrophy due to disturbances of
normal nerve-influences, as that resulting in the salivary gland
after cutting off its nerve-supply.

Atrophy is usually associated with other degenerative
changes, especially fatty degeneration and calcification. Ac-
companying the atrophy of the cells proper of a tissue there
is often an increase in its connective tissue, as, for instance, in
pseudohypertrophic paralysis. In the liver and kidney this
increase in connective tissue — cirrhosis— is often looked upon
as an evidence of chronic interstitial inflammation in contra-
distinction to parenchymatous inflammation.

Hypertrophy.

The term hypertrophy, which properly means over-feeding
or over-nourishment, is applied to an overgrowth of an organ,
without marked alteration from the normal structure. It
implies more than mere enlargement. A carcinomatous liver
is enlarged, but not hypertrophied.

In true hypertrophy there is an increase only in the size of
the cells. Hyper 'plasia, or numerical hypertrophy, is an in-
crease in their number, their size not being increased but
even diminished. Physiologically this condition is seen in the
enlargement of the uterus following impregnation, and gigan-
tism is a remarkable example of general hypertrophy. Patho-
logically, in leukaemia, the spleen is found hypertrophied to
several times its normal size and weight.

Causes : Increased functional activity, which means also in-
creased nourishment, is a most important factor in the pro-
duction of many hypertrophies. When increased work is
thrown upon the heart, for example as the result of valvular
disease, it becomes hypertrophied. Stricture of the urethra
causes hypertrophy of the walls of the bladder. When one
kidney is removed there is a compensatory hypertrophy of its
fellow. So also when part of a secreting gland, like the liver
or pancreas, is removed there is often a hypertrophy of the
remaining portion.

286 PATHOLOGY OF NUTRITION.

Fibrosis.

In fibrosis, or fibroid substitution, there is a wasting of the
true parenchyma-cells and an increase in the connective tis-
sue. It is not, strictly speaking, a degeneration except in
that the new material is considered inferior to the original.
When the change takes place in the central nervous system
it is spoken of as a sclerosis ; in the liver and kidney, as cirrho-
sis. It is often regarded as an evidence of chronic inflamma-
tion, for we know that there often results a great increase
in the amount of connective tissue in an area so affected. But
the change often occurs where there has been no inflammation.
In pseudohypertrophic paralysis, which is not usually re-
garded as an inflammatory process, the true muscle-cells are
almost entirely atrophied, yet by reason of the increase in the
connective tissue the calves of the legs are greatly enlarged.
In fibroid heart and the various scleroses of the central
nervous system there is considerable doubt about the inflam-
matory nature of the change. In the liver and kidneys, how-
ever, it is undoubtedly a frequent sequel of long-continued
inflammations.

TUMOES.

Definition : A tumor is a non-inflammatory, circumscribed
swelling which has no function.

Etiology : Though a great many theories have been ad-
vanced, we actually know but little as to the causation of
tumors. The older authors referred to a peculiar constitu-
tional dyscrasia in this connection. Yirchow laid great stress
upon some unusual irritant as the exciting cause, as, for in-
stance, cancer of the breast following a blow or other injury
to the part; or the development of an epithelioma of the
tongue at the site of chronic irritation produced, for instance,
by a jagged tooth. Cohnheim advanced the theory that " in
an early stage of embryonic development more cells are pro-
duced than are required for building up the part concerned,
so that there remains a certain number unappropriated, which,
owing to their embryonic character, are endowed with a
marked capacity for proliferation." Some irritant or injury
causes a flux of blood to the part and determines the multk

TUMORS. 287

plication of the cells, which until that time have remained
dormant.

With regard to the parasitic origin of malignant tumors,
the many points of similarity in their clinical history and
that of certain infectious diseases, such as tuberculosis, are at
least very suggestive. Should their parasitic origin be demon-
strated they would no longer be classed with tumors, but with
the infective granulomata, which they closely resemble in many
respects. The parasite of cancer is described as a protozoon.
The true significance of the bodies so described is as yet sub
judice. An epithelioma has been successfully transmitted
from one animal to another by artificial inoculation.

The predisposing influence of age is an undoubted factor,
some tumors only occurring at an advanced age, while others
occur preferably in the young.

Heredity plays a doubtful role, the importance of which has
been greatly overestimated.

Classification : Tumors have been variously classified.

Clinically they are divided into benign find malignant. The
former are not dangerous except by reason of pressure they
may exert on vital structures, or by mechanically interfering
with the function of a part, as, for instance, by a tumor of the
brain or larynx.

The latter threaten life and are characterized by certain
well-recognized criteria of malignancy :

First, a tendency of the rapidly multiplying cells of the
tumor to break through normal barriers and spread locally,
infiltrating surrounding tissues. This is especially true of the
malignant variety of epithelial tumors — carcinoma — and to a
less extent of sarcoma, the malignant variety of the con-
nective-tissue group. An adequate explanation of this charac-
teristic is entirely lacking. The imagination of one author
goes so far as to enable him to see in the infiltrating cells of a
carcinoma only a host of invading parasites. In a child
some irritant, as dirty hands, may excite the multiplication
of epithelial cells, which, piling up and cornifying, constitute
a benign wart ; while in one advanced in years a similar irri-
tant induces a rapid multiplication of epithelial cells, which,
instead of piling up on the surface, invade the underlying
tissues, thus constituting a most malignant tumor, a carci-

288 PATHOLOGY OF NUTRITION.

noma — e. g., chimney sweeps' cancer, which seems to result
from the accumulation of soot upon the scrotum.

Non-malignant tumors are circumscribed, often encapsu-
lated— facilitating their complete removal. The absence of
capsule in malignant tumors and their extensive infiltration
of surrounding tissues make their complete removal impossi-
ble, which explains an important clinical characteristic — their
tendency to recur locally.

Second, metastasis, or the occurrence of secondary growths
in various parts of the body, is but an extension of the ten-
dency of malignant tumors to spread locally. Tumor-cells
are carried by way of the lymphatics or bloodvessels to
distant parts, where they multiply, yet retaining all their
original characteristics, such as the tendency to horny degene-
ration of the epidermic cells in some varieties of carcinoma.
The number of these secondary nodules is often so great as to
remind one of the lesions of general miliary tuberculosis.
Benign tumors are usually single.

Third, cachexia: A condition of anaemia, feebleness, and
general impairment of nutrition, which is quite comparable to
that noted in tuberculosis and other chronic infectious dis-
eases, is an evidence of malignancy.

Fourth, rapid growth.

Fifth : It may be said that the more cellular a tumor and
the less its histological structure follows any given type of
tissue — i. e. the more atypical — the greater the probability of
its being malignant.

Histological classification : Inasmuch as the microscopical
study of tumors shows them to be composed of no new tissue-
elements, and to conform more or less closely to types of tissue
normally present in the body, it is quite natural to classify
them according to their microscopic structure. In the study
of normal histology we become acquainted with four types of
tissue — connective, epithelial, muscle, and nervous — and with
these four varieties correspond four types of tumors. ,

In the connective-tissue group there are the fibroma, composed
of fibrous tissue ; the chondroma, of cartilage ; theosteoma, of
bone ; the lipoma, of fatty tissue ; the myxoma, of mucoid tissue
similar to that of Wharton's jelly of the umbilical cord ; the
glioma of neuroglia ; the angeioma of bloodvessels ; and the

TUMORS. 289

lymphangeioma of lymphatics. Corresponding to the two
types of muscle-tissue — the tinstriped and the striped — we have
the leiorayoma and the rhabdomyoma.

The neuromata find their physiological prototype in the
nerve-fibres and ganglion-cells of the central nervous system.

Whereas connective-tissue tumors contain DO epithelial

tissue, in another — the epithelial — group, the neoplasm is

formed almost entirely of epithelial elements, only supported

by & framework of connective tissue. This group includes the

apilloma, the microscopical structure of which closely resem-

es the papillae of the skin or the villi of the intestines ; and
the adenoma, in which the epithelial cells are arranged in such
a manner as to imitate normal glandular structures with a
certain degree of exactitude.

On the other hand the microscopical structure of the malig-
nant tumors— the sarcomata and carcinomata — does not
correspond with any normal type of tissue, but is entirely
atypical.

The sarcoma is a very cellular and highly vascular connec-
tive-tissue tumor which histologically resembles one or another
stage of granulation-tissue, several varieties being described
according to the character of the cells of which it is formed ;
the small round-celled sarcoma having the microscopical ap-
pearances of the earliest stage of granulation-tissue ; and the
spindle-celled sarcoma, that of a later stage of granulation-
tissue as its development approaches fully formed fibrous-
tissue.

The carcinoma, which is composed of epithelial cells atypi-
cal ly arranged in a more or less dense connective-tissue
stroma, is likewise described according to the character of the
epithelial cells of which it is composed, viz., the squamous-
celled carcinoma, or epithelioma ; the columnar-celled, or
adeno-carcinoma, and the sphei^oidal-celled, or carcinoma
simplex.

AVhen a benign tumor becomes malignant it still conforms
to its own type of tissue ; that is to say, one of the connective-
tissue group becomes sarcomatous and not carcinomatous, and
one of the epithelial group becomes carcinomatous and not
sarcomatous.

19— Hist.

290 PATHOLOGY OF NUTRITION.

Table :

1. Of Connective Tissue:

Fibroma,

Lipoma,

Chondroina,

Myxoma,

Osteoma,

Angeioma.

Malignant — Sarcoma :

Small and large round cell,

Spindle-cell,

Myeloid,

Melanotic,

Alveolar,

Angeiosarcoma.

2. Of Muscle-tissue :

Leiomyoma,
Ehabdomyoma.

3. Of Nervous Tissue:

Neuroma.

4. Of Epithelial Tissue :

Papilloma,

Adenoma.

Malignant — Carcinoma :

Squamous-celled — Epithelioma,
Cylindrical-celled — Adenocarcinoma,

Spheroidal-celled — Carcinoma Simplex j J2ncephal

A fibroma is a tumor of fibrous connective tissue, according
to the density of which hard and soft varieties are distin-
guished. The former is composed almost entirely of dense
interlacing bundles of fibres and may be as hard as cartilage
(Fig. 118). Between the fibres are a few compressed or
spindle-shaped cells. In the soft variety round, spindle, and
branching cells are numerous, and the fibres few in number
with wider meshes. All gradations, however, are met with
between the two, and in its cellular richness it may approach a
fibrosarcoma.

These tumors always grow from preexisting connective
tissue. Their most frequent seats are the skin and subcutane-
ous connective tissue, the sheaths of nerves and tendons, and
the periosteum of bones. They are also found growing from
the connective-tissue framework of the mammae, ovaries,

MYXOMA.

291

uterus, and kidneys. They are liable to undergo mucoid and
fatty degeneration.

FIG. 118.

Section of a nodular fibroma (Birch-Hirschfeld). The dense fibrous tissue is in
irregular nodules, between which are bands of less dense fibrous tissue con-
taining bloodvessels.

'- ?

A lipoma is a tumor composed of fatty tissue, similar to
normal adipose tissue, except that the fat-cells are larger,
contain more oil, and are not so regularly arranged. They
are tabulated, often grow to enormous size, and sometimes are
multiple (Fig. 119). They are most common in the sub-
cutaneous fatty tissue of the back, shoulders, and buttocks.
They are liable to myxomatotis and cystic degeneration and
calcification.

A myxoma is a tumor composed of mucous tissue — similar
to that of AVharton's substance of the umbilical cord and the
vitreous humor of the eye, which consists of a gelatinous,
homogeneous, or slightly granular matrix crossed by fine
fibrilla?, in which are imbedded irregular branching and

292

PATHOLOGY OF NUTRITION.

anastomosing stellate or spindle-shaped connective-tissue cells
(Fig. 120).

But few tumors are entirely myxomatous, being combined
with other forms of connective tissue, constituting fibromyxoma,
lipomyxoma, chondromyxoma, myxosareoma, etc.

FIG. 119.

Lipoma of the kidney (Birch-Hirschfeld). The boundary between the adipose
tissue of the tumor and the renal tissue is not sharply defined. The former
occupies the middle of the section and extends to its lower edge.

They are found in submucous and subcutaneous tissue, in
the mammary and parotid glands, and marrow of bone.

A chondroma is a tumor composed of hyaline, elastic, or
fibro-cartilage or more frequently of a combination of these
varieties of normal cartilage, differing therefrom in that the
cells are much less regularly arranged. Hyaline cartilage is
the form most frequently found (Fig. 121). If they occur
in situations in which cartilage normally exists, they are called
ecchondromata, or cartilaginous outgrowths. When they occur

OSTEOMA.

293

in other situations, as in the testicle, parotid and mammary
glands, they are called enchondromata. They are liable to
calcification and retrograde changes.

FIG. 120.

FIG. 121,

Myxoma (from the arm), showing the
characteristic branched anastomos-
ing cells, a few leukocytes, and one
or two spindle-cells. X 200 (Green).

Hyaline chondroma.
(Green).

X 200

FIG. 122.

Ivory exostosis

ne, natural size (Ziegler).

An osteoma is a tumor composed of bone, and may be of
either the dense or cancellons variety. It is said to be
heterologus when occurring in organs unconnected with bone,

294 PATHOLOGY OF NUTRITION.

as in the skin, lungs, meninges, testicle, and parotid gland. If
occurring as an outgrowth from bone, they are known as ex-
ostoses (Fig. 122).

Angeioma,

An angeioma is a tumor composed mainly of bloodvessels.
There are two varieties — simple and cavernous. In simple
angeioma, or leleangiectasis, there is an abundant plexus of ar-
teries, veins, and capillaries as found in the skin in ncevi.
They also occur on mucous surfaces and rarely in the internal
organs.

Cavernous angeioma, which is the more common variety, re-
sembles microscopically the tissue of the corpus cavernosum
of the penis, being made up of large, irregularly shaped, in-
tercommunicating spaces filled with blood, lined by endothe-
lium, and separated from each other by connective-tissue par-
titions. They are most common in the liver, but are found
also in the spleen, kidney, and uterus.

Lymphangeiomata are formed of dilated lymphatic vessels
identical in structure with the hsemangeiomata. Cavernous
lymphangeiomata have been occasionally found in the kidneys
and lymphatic glands. In congenital enlargement of the
tongue — macroglossia, and of the lips — macrocheilia, and in
elephantiasis, there is a diffuse dilatation of lymphatic struct-
ures.

Sarcoma.

A sarcoma is a richly cellular malignant tumor of the con-
nective-tissue group, which, histologically, resembles granula-
tion— i. e.j embryonic or undeveloped connective tissue. The
cells, round and spindle-shaped, are greatly in excess of the
intercellular substance. The more cellular its structure the
greater the malignancy of the growth. Though the amount
of the intercellular substance may be very scant, yet it may
be of such quantity and character as to give rise to special
varieties — fibrosarcoma, myxosarcoma, chondrosarcoma, and
osteosarcoma. The bloodvessels, which in some instances are
extremely abundant, are simple channels lined with a single
layer of cells.

ROUND-CELLED SARCOMATA.

295

Sarcomata are liable to retrograde metamorphoses — fatty
degeneration, caseation, liquefaction, and liberation. Accord-

FIG. 123.

Small round-celled sarcoma of the neck. Section only moderately magnified, show-
ing the extremely cellular character of the growth ; the great friability of the
tissue is owing to the minimal amount of intercellular substance it contains and
the intimate relations between the tissue of the tumor and the walls of rela-
tively large, thin-walled bloodvessels (Dunham).

ing to the character of the predominant cells, several varieties
are described :

Round-celled sarcomata have their prototype in the early

FIG. 124.

«fc*^/«»:A *A*

Large round-celled sarcoma of the tongue, a, large round cell containing three
nuclei ; b, delicate fibrous stroma supporting the cells of the growth. At the
point b this stroma contains a collapsed capillary bloodvessel. The large round
cells are probably of endothelial origin. The growth occurred in a man aged
sixty -one years, and in the course of eight mouths had attained the size of a
hickory -nut (Dunham).

296 PATHOLOGY OF NUTRITION.

stage of granulation-tissue. The cells are about the size of
leukocytes, with large nuclei and but little cytoplasm, though
sometimes they are formed of larger spherical cells. There
is scarcely any stroma between the cells (Figs. 123 and 124).
The tumor is gray or pink in color, usually quite soft, and is
found most commonly in the skin, testicle, eye, ovary, perios-
teum, bone, and subcutaneous connective tissue. When they
occur in lymph-glands and adenoid tissue of mucous mem-
branes they are designated lymphosarcomata, on account of the
appearance of their supporting stroma. Metastasis takes
place through the bloodvessels, secondary growths occurring
most frequently in the lungs.

Spindle-celled sarcomata have their prototype in a more
advanced stage of granulation-tissue — the transitional stage
between granulation-tissue and young cicatricial tissue; the

FIG. 125.

Large spindle-celled sarcoma (Birch-Hirschfeld).

cells are elongated or spindle-shaped and often irregular
and provided with several processes (Fig. 125). They grow
from dense connective tissues, as periosteum, intermuscular
septa, fasciae, and tendons, are firmer in consistency, and grow
less rapidly than the round-celled variety. The amount and
character of the intercellular substance in this and other types

ANGEIOSARCOMATA. 297

of sarcoma vary ; they may be such as to suggest the term
fibrosarcoma, myxosarcoma, chondrosarcoma, etc.

Giant-celled or myeloid sarcomata are characterized by the
presence of large, flat, irregularly shaped, multinucleated cells,

FIG. 126.

Giant-celled sarcoma of the superior maxilla : epulis. a, large giant-cell, with numer-
ous nuclei ; b, tangential section of a similar cell. Aside from the giant-cells,
the growth is composed of spindle-cells and a moderate amount of a fibrous in-
tercellular substance. The tumor was removed from a man forty-one years of
age, and was of slow growth, having attained the size of a filbert in two and a
half years (Dunham).

and arise most frequently from the marrow or periosteum
of bone (Fig. 126). They are of slow growth and less
malignant than the other varieties, though metastasis may
occur.

Alveolar sarcoma is a very malignant variety, which bears a
close resemblance to cancer in that the cells are arranged in
an alveolar fibrous stroma. The cells, however, are not of an
epithelial type, and are separated from each other by fine tra-
becula? extending in from the alveolar walls (Fig. 127). They
are most frequent in the skin, occurring also in lymphatic
glands and serous membranes.

Angeiosarcomata arise from the adventitia of bloodvessels,
which are surrounded by the masses of proliferating round

298

PATHOLOGY OF NUTRITION.

cells. They occur in serous membranes, skin, brain, breast,
and salivary glands. They are relatively benign, metastasis
being very rare.

Endothelial sarcomata, or endotheliomata, are composed
of concentrically arranged cells, strongly resembling the

FIG. 127.

Melanotic alveolar sarcoma of the skin, a, mononuclear ; a', polynuclear sarcoma-
cells with epithelial character ; b, pigment-cells ; c, stroma with bloodvessels
and pigment. X 300 (Ziegler).

endothelial cells lining the lymph-vessels and spaces from
which they have developed (Fig. 128). Degenerative changes
and subsequent calcareous infiltration give origin to the
so-called psammomata or "sand tumors" of the brain.
They occur in the pleura, peritoneum, and meninges of the
brain.

Melanotic sarcoma is an exceedingly malignant variety
arising from pigmented tissues, such as the skin, choroid coat
of the eye, and pia mater. Its structure may be that of any of
the above varieties, though it is usually spindle-celled. The
secondary metastatic growths are likewise pigmented and
of similar structure.

PAPILLOMA.

299

Papilloma and Adenoma.

A papilloma is a wartlike excrescence composed of papillae
resembling those of the skin and mucous membranes or the

FIG. 128.

Endothelioma from the floor of the mouth (Earth). Older portion of the growth.
This has a general alveolar structure, the alveoli being separated by a vascular-
ized areolar tissue, n, n, necrosed groups of endothelial cells ; h, h, similar ne-
crosed masses that have undergone hyaline degeneration.

FIG. 129.

Section of wart of skin, a, coriuni; b, enlarged papillae; c, stratified horny layer.

X 40 (Ziegler).

300

PATHOLOGY OF NUTRITION.

villi of the intestines, and surmounted by epithelium. It may
be a simple, smooth elevation, or have a cauliflower appear-
ance (Fig. 129). They occur especially in the bladder, gastro-
intestinal tract, larynx, and nose.

An adenoma, as its name implies, is a tumor which, histo-
logically, more or less closely resembles normal, tubular, or
acinous glandular structures (Fig. 130). The absence of

FIG. 130.

Adenoma of mamma, a, acini ; 6, ducts ; c, well-marked connective-tissue stroma.

X 30 (Ziegler).

excretory ducts often leads to cystic dilatation of the tubules
or acini, from the accumulation of the secretions of the
glandular elements, giving rise to the term cysto-adenoma.
From the walls of such cysts papillary outgrowths may
occur.

Adenomata are benign, though in some cases there may be
metastasis. Their most frequent situations are the skin, mu-
cous membranes, mammae, kidneys, ovaries, liver, thyroid, and
prostate gland. In the ovaries they are supposed to be the
origin of ovarian cysts, which often reach an enormous size.

CARCINOMA. 301

Adenoma of the liver probably arises from the bile-ducts, as
its epithelial elements differ "in structure from the hepatic
cells.

Carcinoma.

A carcinoma, or cancer, is the malignant variety of the epi-
thelial-tissue group of tumors. The arrangement of the rap-
idly multiplying epithelial cells, of which the tumor is mainly
composed, with reference to the connective-tissue stroma is
atypical, peculiar to carcinoma — not seen in any other tissue
in the body, though often suggestive of glandular structures.
The cells originate from surface or glandular epithelium ;
breaking through normal anatomical boundaries, they infiltrate
the surrounding connective tissue, which in its turn thus pro-
liferates, and thus their mutual interpenetration gives rise to
the microscopical structure which is always diagnostic of carci-
noma—epithelial cells in an alveolar stroma. The cells are very
apt to retain to a certain extent the characteristics of those
from which they originated : if from one of the glands of the
stomach, the new-formed cells also are cylindrical, and often
seem to attempt to reproduce glandular tissue — i. e., there are
variously shaped spaces more or less regularly lined by epi-
thelium. If from the epidermis, the newly-formed squamous
cells may show the same tendency to cornification.

The amount of the stroma varies ; if considerable, the
growth is hard — scirrhous; if scanty, it is soft and brain-like
— encephaloid; further, it is often quite cellular from the
presence of infiltrating leukocytes or newly-formed connective-
tissue cells. Metastasis occurs through the lymphatics, while
in sarcoma it occurs through the bloodvessels. The secon-
dary growths have the same general structure as the primary.

Carcinoma occurs most frequently between the ages of
forty-five and sixty-five, and is found most frequently in the
uterus, gastro-intestinal tract, skin, mammary gland, ovary,
and occasionally in the liver, kidney, thyroid, and prostate
gland. It is quite liable to retrograde changes — fatty and
colloid degeneration, necrosis, and ulceration.

Several varieties are described according to the character
of the epithelial elements — squamous, cylindrj^*.
— which compose the tumor :

LI BR ARY

302

PATHOLOGY OF NUTRITION.

Carcinoma simplex, or spheroidal-celled cancer, arises in
glands with spheroidal epithelium, as, for example, the mam-
msa. The acinous or glandular arrangement of the tissue
from which it grows is soon obscured and replaced by the
perfect alveolar structure typical of cancer. In the earliest
stage of its growth there would be simply noted at a given
point within an acinus a proliferation and piling up of the
epithelial cells. Soon they break through the basement-mem-
brane and infiltrate the surrounding connective tissue. The
cells are generally spheroidal unless altered by mutual press-
ure. According to the density of the connective-tissue stroma,
two varieties are distinguished, the scirrhous and encephaloid.

In the scirrhous variety the epithelial element is relatively
small ; the tumor is hard and grows slowly (Fig. 131). In

FIG. 131.

Scirrhous of mamma. X 100 (Ziegler).

encephaloid the stroraa is scanty, the tumor of soft consis-
tency and rapid growth (Fig. 132).

Cylindrical-celled cancer, or adenocardnomaf arises from
surfaces covered with cylindrical epithelium, as from the
glands of the gastro-intestinal tract. Especially in the early

SQUA MO US-CELLED CANCER. 303

stage of development, its general structure is distinctly gland-
ular, consisting of tubular or rounded gland-like spaces or
alveoli lined with cylindrical epithelium. It is distinguished
from simple adenoma, however, which it greatly resembles,
by the irregular arrangement of the marginal epithelium, by
the masses of epithelial cells which often completely fill the
lumen of the alveoli, especially in the older parts of the

FIG. 132.

Medullary carcinoma of the mammary gland (Hansemann). The stroma of the
tumor is here reduced to a minimal amount of areolar tissue containing the
vascular supply of the growth.

tumor, and by epithelial cells which have broken through the
basement-membrane and infiltrated the connective-tissue
stroma between the alveoli.

Squamous-celled cancer, or epithelioma, arises from surfaces
covered by stratified squamous epithelium, as from the skin,
oesophagus, larynx, lips, etc. The proliferating epithelial
cells show the characteristic tendency noted in all cancers to
extend beyond normal limits and infiltrate adjacent tissues.
The tumor is found to be composed of masses of flat epithelial
cells grouped in conical or irregularly shaped processes or
columns of variable length and breadth, simple or branching,
and separated from one another by a scanty connective-tissue
stroma. At many places in the deeper parts of the tumor, as

304

PATHOLOGY OF NUTRITION.

the result of the pressure exerted by the rapid cell-prolifera-
tion and the lack of space, the flat cells are found on edge
and concentrically arranged in whorls, which often have a
glistening appearance as the result of a horny transformation
or cornification — constituting the so-called " pearly bodies"
(Fig. 133).

Epitheliomata appear as elevated nodular masses or diffuse
infiltrations of rather slow growth, very prone to ulceration

FIG. 133.

Epithelial pearl-body from an epithelioma of the lip. a, pearl-body ; b, surrounding
epithelium, forming one of the epitheliomatous tongues or co'lumns ; c, round-
celled infiltration of the contiguous fibrous tissue (Dunham).

and great destruction of tissue. Metastasis may occur, but is
not common. The term colloid cancer is applied to any of
the above forms which has undergone a colloid degeneration.

Myoma.

A myoma is a tumor composed of muscle-tissue. There are
two varieties, corresponding to the two varieties of muscle-
tissue — rhabdomyoma, formed of striped, and leiomyoma, of
unstriped muscle-tissue.

Rhabdomyomata are exceedingly rare. In a few instances

LEIOMYOMATA.

305

such tumors have occurred congenitally in the heart and caused
death. Such tumors have also been found in the kidney,
mixed with sarcomatous tissue and malignant in proportion to
the amount of the latter (Fig. 134).

Leiomyomata are of much more common occurrence — the
most frequent seat being the uterus, though they may occur
wherever unstriped muscle-tissue is normally found. They are
formed of bundles of muscle-cells, closely packed and inter -

FIG. 134.

Rhabdomyosarcoma of the kidney, a, a, a, imperfectly developed striated muscle-
fibres ; b, tissue composed of small round and spindle-shaped cells, separated by
considerable delicate fibrous intercellular substance. In other parts of the growth,
which was the size of the fist, this tissue was more distinctly sarcomatous and
the amount of muscular tissue smaller. The child from which this tumor
was removed was about two years old.

lacing in every direction. When there is a large amount of
connective tissue between the bundles they are termed fibro-
myomata. On account of the wavy course of the muscle-
cells, in microscopical section they seldom are seen in their
entire length, though they may be isolated by teasing out a
portion of the tumor. The characteristic feature is the
presence of the long rod-shaped nuclei — circular, however,
if cut transversely (Fig. 135). Their appearance suggests
spindle-celled sarcoma, but in the latter the cells are not

20— Hist.

306

PATHOLOGY OF NUTRITION.

arranged in regular bundles and their nuclei are not oblong,
but oval ; sarcomatous transformation, however, may occur.
Myxomatous degeneration and calcification are the most fre-
quent retrograde changes to which they are liable.

FIG. 135.

Leiomyoma of the uterus (Birch-Hirschfeldj.

Neuroma and Glioma.

A true neuroma is a very rare tumor, composed of nerve-
fibres and ganglion-cells. The so-called false neuromata are
usually fibromata occurring in the course of a nerve and
found also as bulbous swellings of the cut ends of the nerves
in amputated limbs.

A glioma is a tumor composed of tissue similar to neuroglia,
occurring in the brain and less frequently in the spinal cord
and the retina of the eye. They are formed of a very delicate
network of fibres, imbedded in which are numerous round
or oval cells with very large nuclei. They are benign, though
liable to undergo sarcomatous transformation.

CYSTS.

Teratoma.

307

Teratomata are tumors of complex structure, sometimes
consisting of a mingling of several types of tissue as gland,
nervous, muscle, and connective tissue ; sometimes being com-
posed of more or less complete organs, as breasts, nerves,

FIG. 136.

Dermoid cyst of the ovary, showing all the structures of true skin except sweat-
glands— viz., epithelium, rudimentary papillae, fibrous tissue or cutis vera, hair-
follicles, large sebaceous glands. X 18 (Boyd;.

muscles, portions of intestine — constituting so-called dermoid
tumors, which, however, usually present themselves as cysts
filled with hair, teeth, and occasionally bone, muscle- and
nerve-tissue. Teratomata also include certain malformations
and monstrosities (Fig. 136).

CYSTS.

A cyst is a cavity, usually with a distinct membranous wall,
which contains a fluid or semifluid material. They are not
really tumors, though usually considered in connection with
the latter. They are generally classified according to the
method of their formation.

308 PATHOLOGY OF NUTRITION.

Retention-cysts result from the accumulation or retention of
the natural secretion of a gland, due to the obstruction of its
duct. As examples may be mentioned sebaceous cysts or
wens ; and ranula, which results from obstruction of the ducts
of the salivary gland. As the result of obstruction of a ureter
the whole kidney may be converted into a cyst.

Disintegration-cysts result from degenerative softening and
disintegration of normal or pathological tissues. This may
occur after hemorrhage into the brain — apoplectic cyst. Para-
sitic cysts might be included under this head — for example,
hydatid cysts. Tumors, especially sarcomata and chondro-
mata, are liable to cystic degeneration.

SPECIAL PATHOLOGY.

CHAPTER III.
DISEASES OF THE BLOOD.

PLETHORA.

THE condition of plethora, by which is understood an excess
of blood in the body, was regarded by the older writers as of
great importance, and most serious consequences were at-
tributed to it. Clinically, its presence was supposed to be
indicated by redness of the face and a vigorous circulation
occurring in high livers.

Experimental evidence goes to show that if the amount of
blood in the vessels is artificially increased the result is but
temporary, as the excess is carried off by the kidneys in a few
hours.

OLIGEMIA.

The term oligemia indicates a diminution in the total quan-
tity of blood. This undoubtedly does occur after profuse
hemorrhages, severe vomiting, and diarrhoea. There is rea-
son to believe it exists in starvation and certain cachectic
conditions.

QUALITATIVE CHANGES IN THE BLOOD.

Alterations in the plasma: The amount of fibrin formed
from the blood was carefully investigated in the days of
frequent venesection. It is greatly increased in certain acute
inflammations, as pneumonia, pleurisy, and peritonitis. In
some infectious diseases, as typhoid and smallpox, the amount
of fibrin is not increased ; though if a pneumonia or pleurisy
occurs as a complication such an increase is immediately
noted. A reduction of the fibrin-forming property of the
blood has been occasionally observed, as in purpura and

309

310 DISEASES OF THE BLOOD.

scurvy. Our knowledge regarding chemical changes in the
plasma is exceedingly meagre.

Alterations in the red corpuscles : Polycythcemia or erythro-
cytosix, in which there is an actual increase in the number of
red-cells in a given bulk of blood, is of relatively rare occur-
rence. Hay era states that they may be increased from the
normal five million to six and a half million per cubic milli-
metre in the algid stage of cholera.

Oligocythamta, in which there is a reduction in the number
of red cells, is very frequently noted. It may occur tempo-
rarily from a considerable loss of blood, or permanently as
the result of interference with the formation of the red
globules in the body. According to Hay em, if the condition
is brought about rapidly, as by hemorrhage, a reduction in
their number beyond one million per cubic millimetre is almost
certain to prove fatal. When this reduction is progressive the
body seems to adapt itself to these new conditions, patients
being seen active and earning their living with less than two
million red blood-cells per cubic millimetre. Extreme and
fatal cases have been recorded in which there were less than
three hundred thousand per cubic millimetre.

Alterations in the size and shape of the red corpuscles are
frequent. Their normal average diameter is seven and a half
microns — 7.5 p. (IJL= ToVfr millimetre).

Microcytes are dwarf corpuscles two to five microns in
diameter. Macrocytes, or megalocytes, are giant-cells nine to
twenty microns in diameter. Poikilocytes are oval, pear-
shaped, or variously distorted corpuscles. Erythroblasts are
nucleated red blood-cells, which are termed, according to their
size, normoblastSj microblasts, and megaloblasts.

While the normoblasts occur normally in bone-marrow, and
would seem to be present in the circulation in this immature
form as the result of an unusual effort on the part of the
blood-making organs to improve the blood, the megaloblasts
are never present in healthy adult marrow, and, as they do
not develop into mature corpuscles, they are looked upon as a
degenerative type.

The microblasts are not so frequently met with as the other
two varieties. Karyokinetic figures are sometimes seen in
the nuclei of erythroblasts.

CHANGES IN THE BLOOD. 311

Red blood-corpuscles have an especial affinity for eosin and
other acid stains, and in a mixture of dyes, such as haema-
toxylin and eosin, stain only with one of them, the eosin,
which property is termed monochromatophilia. Pathologi-
cally, however, they may develop an affinity also for basic
dyes ; when stained with haematoxylin and eosin mixture they
present a violet or purple color, instead of the normal pink —
this is termed polychromatophilia.

Alterations in the leukocytes : Hypoleukocytosis or letiko-
penia — a deficiency in the number of leukocytes — is associated
with certain conditions, as, long-continued fevers, like typhoid,
when uncomplicated by inflammatory processes ; with tuber-
culosis and inanition.

Leukocytosis — a transient increase in the number of leuko-
cytes above the normal ten thousand per cubic millimetre — is
noted in connection especially with inflammatory processes
and infectious diseases. The degree of the leukocytosis in
pneumonia and most inflammatory affections is regarded as
an index of nature's power to combat the disease, its entire
absence being an ill-omen. In typhoid fever, malaria, in-
fluenza, and acute miliary tuberculosis the leukocytes are not
increased, which fact may at times be of some diagnostic
value. Usually it is the poly nuclear variety of leukocyte
which is increased. Malignant tumors, especially sarcomata,
are accompanied by an increase in the number of leukocytes
— even to the extent of fifty thousand per cubic millimetre or
more — the small mononuclear being the variety mainly affected.
In syphilis, rickets, and other cachexias there may be a similar
leukocytosis. There is also an increase in the number of
leukocytes after hemorrhage.

In leukaemia there is an enormous and permanent increase
in the number of leukocytes — one to three hundred thousand
per cubic millimetre in moderate cases.

Alterations in the blood-plates are as yet but little under-
stood.

The amount of haemoglobin contained in each red globule
varies normally with the size of the corpuscle, though patho-
logically this relation does not exist. In most cases the
amount of haemoglobin in each globule is diminished ; in some
cases, however, there is an actual increase in the amount of

312 DISEASES OF THE BLOOD.

haemoglobin per red corpuscle — ascertained by comparing the
number of red cells per cubic millimetre with the percentage
of haemoglobin.

THE ANAEMIAS.

The term anaemia includes a variety of conditions in which
there are qualitative alterations in the blood, the most con-
spicuous evidence of which, clinically, is pallor of the skin
and mucous membranes, due to a reduction in the amount of
haemoglobin, whether from a reduction in the amount of
blood, in the number of red corpuscles, or in the coloring-
matter alone.

Reduction in the number of red corpuscles — oligocythcemia,
and of the amount of haemoglobin — oligochromcemia, are usu-
ally associated, though the latter may be present without
alteration in the number of red cells, as is seen especially in
chlorosis.

The anaemias are usually divided into two classes clinically
— the primary or essential, and the secondary or symptomatic.

The former include simple primary anaemia, pernicious
anaemia, chlorosis, leukaemia, and Hodgkin's disease, neither
of which is dependent on any preceding affection.

The latter include those anaemias produced by disturbances
outside of the haemopoietic system — e. g., tuberculosis, malig-
nant disease, etc.

Primary Anaemias.

Chlorosis is a primary anaemia, occurring principally in girls
about the time of puberty, characterized by an excessive reduc-
tion in the amount of haemoglobin and, in most cases, a peculiar
sallow complexion having a somewhat greenish tinge, which
has won for it the term green-sickness. The red corpuscles may
be normal in number, but generally in prolonged cases there
is a considerable reduction — never so great, however, as the
percentage-reduction of haemoglobin ; in other words, the
amount of coloring-matter in each individual corpuscle — la
valeur globulaire — is reduced. This difference may be as
great as 30 per cent. ; while the number of corpuscles in a
given case may be reduced to only two or three million per
cubic millimetre, the quantity of haemoglobin may be less
than 20 or 30 per cent, of normal.

PRIMARY ANAEMIAS. 313

When the red blood-corpuscles are reduced in number they
are usually more or less altered in shape, according to the
degree of the oligocythsemia. Poikilocytes, microcytes, and
polychromatophiles are frequently present, and, when the con-
dition is very severe, megalocytes may be quite numerous;
nucleated red blood-corpuscles — usually normoblasts — are
sometimes seen. The number and variety of leukocytes are
normal in uncomplicated cases.

The only associated organic lesion which has been noted
is a congenital smallness of the heart, bloodvessels, and
genital organs.

Progressive pernicious anaemia is a severe anaemia which has
no apparent cause and tends uninterruptedly toward a fatal
issue. The number of red blood-corpuscles is reduced to a
greater degree than in any other condition, sinking below five
hundred thousand per cubic millimetre, even to one hundred
and forty-three thousand in one case which has been recorded.

A characteristic feature is the average increase in size of
the red corpuscles. Microcytes may occur, but are not com-
mon. Erythroblasts, poikilocytes, and polychromatophiles are
frequently noted. The haemoglobin is always reduced, but
never to the same extent as the red blood-corpuscles. The
leukocytes undergo no important change.

In some cases it has been possible to assign a cause.
Atrophy of the gastro-intestinal mucous membrane and certain
intestinal parasites, especially the anchylostoma duodenale,
produce a secondary anaemia, often not distinguishable from
progressive pernicious anaemia. The anaemia is usually looked
upon as resulting from the excessive destruction of blood
rather than from its defective formation. The pigmentation
of various organs, the jaundice often present, and the excess
of coloring-matter in the urine suggest this conception of its
nature.

The various viscera are pale and bloodless, and in a more or
less advanced stage of fatty degeneration.

A simple primary anaemia arising without any apparent
cause is not recognized by many writers, yet cases do occur in
which the characteristic features of both chlorosis and per-

314 DISEASES OF THE BLOOD.

nicious anaemia are absent. The red blood-corpuscles and
haemoglobin are usually reduced to the same degree ; the leuko-
cytes undergo no important change either in number or kind.

Leukaemia or leukocythsemia : The term leukaemia — white
blood — was first proposed by Virchow7, in 1845, for cases in
which there was an enormous increase in the number of leuko-
cytes in the blood, associated with enlargement of the spleen
and lymphatic glands. The condition had previously been
regarded as an inflammation or suppuration of the blood.

The disease is well named, for at times the blood is so
white it resembles milk or pus. The older writers were
accustomed to speak of the relations existing between the
number of white and red corpuscles ; but as this depends also
on fluctuations in the number of red corpuscles, it is more im-
portant to know the exact number of leukocytes per cubic
millimetre. Instead of one leukocyte to five or six hundred
red cells, the proportion is frequently one to eight, even one
to two or three ; in cases of moderate severity there are one
to three hundred thousand per cubic millimetre — five hundred
thousand per cubic millimetre not being infrequent.

Yet it is not so much the number of leukocytes, which is
characteristic of this disease, as the character of the predomi-
nant variety ; for the proportion of one to eight has been
noted in non-leukaemic anaemias, and in some cases of leuko-
cytosis there may be as many as one hundred thousand white
blood-corpuscles per cubic millimetre.

Virchow recognized two forms of the disease, one character-
ized by enlargement of the spleen, in which the blood showed
an excessive number of large white cells ; and another charac-
terized by enlargement of the lymphatic glands, in which the
small variety of leukocyte predominated.

A third form of the disease was later described by Neu-
mann, in which there were marked changes in the marrow of
the bones.

Though it is customary to speak of lymphatic, splenic, and
myelogenous varieties of the disease, these different forms are
often associated. There is some doubt as to a pure splenic
variety existing without accompanying changes in the bone-
marrow.

LEUKEMIA OR LEUKOCYTHJEMIA. 315

The spleno-medullary variety of leukaemia is especially recog-
nized by the presence in the blood of numbers of large-sized
leukocytes, which have been called myelocytes on account of
their supposed origin in bone-marrow. These cells are rarely
if ever seen in normal blood ; they are usually 1 Q/JL to 20/j in
diameter, though occasionally not much larger than a red
corpuscle, when they can only be distinguished from the
mononuclear leukocytes by the presence of neutrophilic gran-
ules in their protoplasm, or sometimes of eosinophilic granules
— eosinophile myelocytes. When the blood is stained with
haematoxylin and eosin these neutrophilic granules cannot be
seen ; but if Ehrlich's triple stain is employed they are readily
recognized. In this variety of leukaemia the myelocytes often
make up 30 to 50 per cent, of the total number of leuko-
cytes, while in other diseases in which they rarely occur they
never exceed 2 to 9 per cent.

The relative number of eosinophiles — normally constituting
2 to 4 per cent, of the white blood-cells — is not usually in-
creased, though there is always an absolute increase in their
number — 50 to 80 per cent, of which are eosinophile mye-
locytes. It was formerly supposed that a relative increase
in the eosinophiles was diagnostic of leukaemia ; they are in-
creased to a much greater extent, however, in some other
affections — notably in asthma and diseases of the skin — and
often are even diminished in leukaemia. The number of poly-
nuclear neutrophiles is relatively diminished, making up but 50
per cent. — in some cases even less than 10 per cent, of the total
number of white blood-cells ; an increase would suggest some
inflammatory complication. The small lymphocytes are also
relatively reduced in number, constituting but 3 to 5 per cent.,
instead of 15 to 25 per cent, of the total number of leukocytes.

Basophilic myelocytes and small leukocytes are occasionally
noted, their protoplasm containing granules which have a
selective affinity for basic dyes.

The red blood-corpuscles are usually reduced to two or three
million per cubic millimetre, and proportionally likewise
the haemoglobin. Alterations in the size, shape, and stain-
ing properties of the red cells may be noted ; and erythro-
blasts are always found at some stage of the disease —
mostly normoblasts, though some megaloblasts and micro-

316 DISEASES OF THE BLOOD.

blasts. The presence of these nucleated red blood-cells is
especially characteristic when the oligocythsemia is slight-
in fact, it is the only disease in which they are present under
that condition. The manner in which this excessive accumula-
tion of leukocytes is brought about, whether due to an increased
proliferation or a diminished destruction of these elements, is
not known. Some maintain that it is primarily a disease of
the blood-making organs — the spleen, lymphatic glands, and
bone-marrow — while others believe the changes in these
organs to be secondary to the alterations in the blood. The
enlargement of the spleen, which is nearly always present, is
the result of an enormous increase of the lymphatic elements.
The marrow of spongy and long bones becomes yellowish in
color; microscopically the marrow-cells are found to be
greatly increased in number. The lymphatic glands are also
sometimes involved ; in fact, any lymphatic tissue in the body
may be affected.

In the lymphatic variety of leukaemia, which is of much
less frequent occurrence, the enlargement of the lymphatic
glands is especially marked. A pure lymphatic form is rare,
usually there being some involvement of the spleen and bone-
marrow. The leukocytes are never increased to the same
extent, the large and small mononuclear elements making up
95 per cent, of their number. Myelocytes are present in very
small numbers only, if at all ; the eosinophiles and polynu-
clear neutrophiles are relatively and absolutely reduced.

The oligocythaBmia is much more marked than in the spleno-
myelogenous variety ; nucleated red blood-corpuscles, how-
ever, are extremely infrequent.

Hodgkin's disease, malignant lymphoma, lymphosarcoma , or
pseudoleukcemia, resembles leukaemia in all respects except in
that there is no increase in the number of leukocytes in the
blood. The lymphatic glands throughout the body are
enlarged as a result of a hyperplastic proliferation of the lym-
phatic elements. As in leukaemia, the spleen, bone-marrow,
tonsils, lymphatic follicles of the intestinal mucous membrane,
and all the other lymphatic tissues in the body may be affected.
Nodules, from the size of millet-seed to that of a walnut,
composed of lymphoid cells, may occur in the liver, kidneys,

SECONDARY ANAEMIAS. 317

lungs and serous membranes ; also, rarely, in the ovaries, tes-
ticles, heart, and brain.

At the beginning of the disease the blood is found to be
normal, but soon the anaemia and cachexia become prominent.
When the anemia is pronounced, alterations in the size and
shape of the red blood-corpuscles occur, and a few nucleated
erythrocytes — usually normoblasts — may be noted, as in other
severe anaemias.

The percentage-reduction in hemoglobin is often greater
than that of the red corpuscles — a so-called chlorotic con-
dition of the blood.

Cases are sometimes observed in which the spleen alone is
involved, and are described under the term splenic anemia.

Secondary Anaemias.

Whatever the cause of secondary or symptomatic anaemias,
they have certain common characteristics. There is usually
a greater percentage- reduction of hemoglobin than of red
blood-corpuscles ; in mild cases the number of red cells is not
reduced, though the haemoglobin varies from 60 to 75 per cent,
of normal. The individual corpuscular richness in hemo-
globin is never above par, as in pernicious anemia. In severe
cases the oligocythemia may be almost as great as in the latter
disease. Alterations in the size and form of the red cells
occur ; microcytes and megalocytes are sometimes noted, the
former more frequently, however.

Poikilocytosis and degenerative changes — vacuolation and
polychromatophilia — occur in the red blood-corpuscles; nor-
moblasts, the presence of which may be regarded as evidence
of a regenerative effort on the part of the blood-making organs,
are likewise to be seen.

The number of leukocytes varies considerably ; if there is
a leukocytosis, it consists of an increase in the polynuclear
neutrophiles.

CHAPTER IV.

DISEASES OF THE CIRCULATORY SYSTEM.

FIG. 137.

HEART AND PERICARDIUM.

ATROPHY.

Hypoplasia of the heart — a congenital smallness — is often
associated with a similar malformation of the aorta and other
bloodvessels, and of the generative organs. This condition
has been noted especially in connection with chlorosis. The
heart is uniformly affected in all its parts.

Brown atrophy, an acquired change associated with pigmen-
tation, is seen in cases of wasting diseases, as tuberculosis and

cancer ; and especially also in old
age. The heart is dark brown in
color, and quite small, often not
weighing more than a third of
normal ; its walls are thin and
cavities contracted. The epicar-
dium is frequently wrinkled, the
coronary arteries prominent and
tortuous, due to the loss of subperi-
cardial fat. On microscopical
section the muscle-fibres are found
to be thinner than normal, and in
the centre of each is a brown spot
of pigment (Fig. 137). Similar
pigmentation is also often asso-
ciated with cardiac hypertrophy.
The resulting symptoms are not
usually serious, as the lessened
power of the cardiac muscle is but commensurate with the
decreased demand made upon it,

318

Brown or senile atrophy of the
heart (Ribbert). The muscle-
fibres are reduced in diameter;
at the ends of the nuclei are col-
lections of pigment-granules.

HYPERTROPHY.

319

HYPERTROPHY.

Three varieties of cardiac hypertrophy are usually described,
according to the size of the cavities associated with the
increased thickness in the muscle-walls; simple, in which the
cavities are of normal size ; concentric, in which they are
smaller than normal ; and eccentric, in which they are dilated.
In x'nnple dilatation also the heart is enlarged, but not hyper-
trophied.

Causes : The hypertrophy is the result of increased demands
made upon the heart-muscle. Stenotic and incompetent valves
are a very frequent cause. General arterio-sclerosis, often

--LV

Hypertrophy of left ventricle (front view). Heart is elongated. Septum occupies
middle of anterior surface. (From a case of granular kidney from a specimen
in Charing Cross Hospital Museum (Green).)

associated with interstitial nephritis, greatly increases the work
of the left ventricle and leads to its hypertrophy (Figs. 138
and 139). Obstruction to the pulmonary circulation, as, for
instance, in fibroid phthisis and emphysema, leads to hyper-
trophy of the right ventricle (Figs. 140 and 141). Simple
functional overactivity, as in hysteria and exophthalmic goitre,
may lead to a uniform hypertrophy of the whole heart.

Dilatation occurs where the heart-muscle is exhausted and
unable to overcome the impediment.

Microscopically is noted an increase in the size of the
muscle-fibres ; there is also probably an increase in their

320

DISEASES OF THE CIRCULATORY SYSTEM.

number. Fibroid and fatty degenerative changes are usually
associated with dilatation. The size and weight of the organ

A —

•~LV

Hypertrophy of right ventricle (front view). Heart is quadrilateral and septum is
displaced to the left. Right auricle is dilated. (From a case of chronic bron-
chitis and emphysema; specimen in Charing Cross Hospital Museum (Green).)

FIG. 141.

-RV

LV-

Anterior half of heart (Fig. 138), seen
from behind. Left ventricle forms
the whole of apex. Wall of LV :
wall of RV: : 10 : 2 (normal pro-
portion, 5 : 2) (Green).

Anterior half of heart (Fig. 139), seen
from behind. Right ventricle is seen
to take greater share in formation of
apex than left ventricle does. Wall of
RV is much thickened, but not so
thick as that of the left. Tricuspid
orifice and RA are dilated (Green).

FATTY INFILTRATION. 321

are often so greatly increased as to justify the term " cor bovi-
nuni". As long as the hypertrophy is compensatory there are
no symptoms ; but when the cardiac muscle can no longer
meet the demands made upon it, the results are most serious.
If the left ventricle is at fault, there is a passive congestion
of the pulmonary circulation. When the right ventricle is
at fault, or in turn becomes involved, there occur passive con-
gestion of the general systemic circulation and dropsy.

DEGENERATIVE CHANGES.

Cloudy Swelling.

Cloudy swelling occurs either as an early stage of inflamma-
tion or as a precursor of fatty degeneration. It is noted
especially in the course of diphtheria, smallpox, scarlet fever,
and other infectious diseases; also in rheumatism and after
severe burns.

The myocardium is soft — even friable, pale, and looks as
if it had been slightly boiled.

Microscopically the muscle-fibres are seen to be swollen — the
spaces between the individual muscle-fibres being smaller than
normal — and their transverse striations are indistinct. The
fibres appear as though seen through ground glass or a layer
of dust, due to the presence of innumerable fine albuminous
granules.

Fatty Infiltration.

Normally there is a certain amount of adipose tissue beneath
the epicardium, especially along the course of the coronary
arteries, lower border of the left ventricle, and at the apex.

Pathologically the adipose tissue may not only form a thick
coating over the entire surface, but even extend into the walls
of the heart between the muscle-fibres, deposits even appear-
ing at places under the endocardium. The muscle-fibres
themselves are not involved, except that they are often
atrophied as the result of pressure, when the accumulation of
adipose tissue is excessive. Besides the cardiac weakness thus
resulting, a fatty degeneration of the muscle-fibres may be
induced.

21— Hist.

322 DISEASES OF THE CIRCULATORY SYSTEM.

Fatty Degeneration.

In fatty degeneration the individual muscle-fibres are in-
volved, the cell-protoplasm being replaced to a great extent by
small globules of fat. These droplets appear first in the
neighborhood of the nucleus ; but may finally occupy the
whole fibre, giving rise to an appearance somewhat resembling
cloudy swelling; the granules are larger than in the latter
condition, however, dissolve in alcohol, chloroform, or ether,
and stain black with osmic acid (Fig. 142). The main factor

FIG. 142.

Mmm?

W: PflP'IV'f ^;v;'!^ilu^
fc;llli:l|l^;ipil!i

/ * * , • / t ,.. •(

WRi***

Well-marked chronic fatty degeneration of heart, a, healthy ; b, fatty degeneration
of muscle-fibres. X 80 (Ziegler).

in its production is either a general or a local anaemia. The
local anaemia may be brought about by sclerosis of the coro-
nary arteries, or an improper circulation of the blood through
them as the result of a valvular lesion. The condition is

MYOCARDITIS. 323

frequently associated with pernicious anemia, leukaemia,
phthisis and other wasting diseases ; and with arsenic- and
phosphorus-poisoning.

The macroscopic appearance of the heart is quite character-
istic. It is usually pale, flabby, and dilated. The degene-
rative change generally occurs in patches, the matted appear-
ance produced thereby being most readily seen from within,
beneath the endocardium. When the process is diffuse the
cardiac muscle has a uniform yellowish hue.

Myomalacia cordis is a localized softening — a necrosis — of
the heart-wall due to embolic or thrombotic obstruction of the
coronary arteries. The area from which the blood is cut off
is often wedge-shaped, pale yellow in color, and depressed
below the surface.

Amyloid and hyaline degenerations are sometimes noted.
Calcareous infiltration of the myocardium occurs, but is ex-
tremely rare.

INFLAMMATIONS.

Myocarditis.

Inflammation of the heart-muscle may be primary, but is
much more frequently secondary to a peri- or endocarditis.
It occurs in the course of acute infectious fevers, as typhoid,
diphtheria, scarlet fever, smallpox, and puerperal septicaemia.
The heart-muscle is friable and has a yellowish-red and
matted appearance ; the cavities are usually dilated. Micro-
scopically, there is noted in addition to the cloudy swelling
of the muscle-fibres a round-celled infiltration of the sup-
porting connective-tissue framework ; some are proliferated
connective-tissue cells, the majority, however, being migrated
leukocytes. Abscesses, appearing macroscopically on section
of the heart-wall as yellowish-white spots, may occur. They
are most frequent in the anterior wall of the left ventricle, and
vary from the size of a pinhead to that of a cherry.

In fibrous or chronic myocarditis there is a great increase in
the interstitial connective tissue. This fibroid change -or
substitution may be diffuse or circumscribed. Diffuse inter-
muscular sclerosis is often associated with general arterio-

324 DISEASES OF THE CIRCULATORY SYSTEM.

sclerosis and fibroid change in the kidneys and other organs.
As a result, the heart may be hypertrophied by the increased
work imposed upon it, but much more frequently the muscle-
fibres are atrophied by the mechanical pressure of the newly
formed fibrous tissue, and are found to have undergone
granular and fatty degeneration. Circumscribed areas of
fibroid substitution are often consecutive to degenerative
changes produced by obstruction of the coronary arteries. A
saccular dilatation — aneurism — may result from the thinned
heart-wall giving way to pressure from within at such a
point.

Endocarditis.

Inflammation of the endocardium usually aifects the valves ;
when affecting the cavities of the heart it may be designated
specially as mural endocarditis.

Acute endocarditis is rarely a primary affection. The most
frequent cause is acute articular rheumatism. It occurs also

FIG. 143.

FIG. 144.

Inflammation of aortic valves, the ear-
lier stage of the process, showing the
situation of the inflammatory gran-
ulations (Green).

Inflammation of mitral valve, the ear-
lier stage of the process. Valve seen
from the auricular surface, showing
the situation of the inflammatory
granulations (Green).

in the course of pneumonia, puerperal septicaemia, scarlet fever,
typhoid fever, gonorrhoea, and, in fact, in any acute infectious
disease. It occurs also in Bright's disease, cancer, and diabetes.
The most characteristic lesions are the so-called warty
vegetations formed along the line of contact of the valves,
especially on the auricular aspect of the mitral, and in a row

CHRONIC ENDOCARDITIS. 325

of bead-like elevations on the ventricular surface, some little
distance from the margins of the cusps of the aortic (Figs.
143 and 144). These small warty elevations are less fre-
quently seen on the tricuspid and pulmonary valves, and on
the chordae tendinese and parts of the mural endocardium.
They crumble and can be easily detached by the finger,
leaving behind a slightly roughened surface, or possibly a
small ulcer the size of the base of the vegetation. The change
in the endocardium produced by the inflammatory process
and the extra irritation and friction at the line of contact of
the valves on closure, invite the deposition of fibrin ; there
is an active proliferation of the endothelial cells, which,
together with migrating leukocytes, infiltrate the layers of
fibrin and tend to bring about the organization of the clot
which has formed.

In some cases the inflammatory process is especially severe
and there is a tendency to suppuration and ulceration. Small
collections of pus may be seen at the base of the valves. The
masses of fibrinous deposit are more abundant and irregular,
occurring indiscriminately over the endocardial surface of the
valves and heart-wall. Where there has been actual destruc-
tion of tissue there will be noted on section, microscopically,
at the bases of these vegetations, typical granulation-tissue,
to which the clot is firmly adherent. If the section is prop-
erly stained, micro-organisms may usually be seen in the
superficial layers of the endocardium. The vegetations are
liable to be broken off and carried in the circulation, as emboli,
to distant parts. If the micro-organisms are likewise trans-
ported, metastatic abscesses in various organs are produced.

Chronic endocarditis results in various distortions of the af-
fected leaflets of the valves, and, in consequence, serious dis-
turbances in the circulation. The vegetations become fibrous
and have a broad base. As in all chronic inflammations, there
is a tendency toward the overproduction of connective tissue.
The proliferating endothelial and connective-tissue cells and
infiltrating leukocytes become organized into fibrous tissue.
The valves are thickened, rigid, and eventually retracted and
distorted. The opposed inflamed leaflets of the valve may
become agglutinated or firmly adherent to the adjacent heart-
wall and cause still further deformity. The chordae tendinese

326 DISEASES OF THE CIRCULATORY SYSTEM.

also become thick and rigid, and interfere with the function of
the valves. The dense cicatricial connective tissue may be-
come infiltrated with lime salts.

In some cases the inflammatory process may be chronic
from the first. This is especially liable to occur in persons of
advanced years, and also in connection with chronic alcoholism,
syphilis, and gout, which are active factors also in producing
general arterio-sclerosis. The alterations in the valves lead to
stenosis, an obstruction to the flow of blood ; or insufficiency,
when the valves cannot close, and thus prevent the regurgita-
tion of the blood. A valve may be both stenotic and insuf-
ficient.

Either condition necessarily leads to imperfect circulation
of the blood through the heart. The natural result of the in-
creased work thrown upon the heart-muscle is hypertrophy.
When this compensatory hypertrophy fails, most serious
changes occur in the various organs. The lungs become
cedematous and gradually indurated, as the result of an in-
creased proliferation of the interstitial connective tissue. The
pulmonary vessels are distended, even varicose ; thrombi may
form, as the result of the sluggish circulation. The liver,
spleen and kidneys are enlarged by reason of their passive
congestion. The countenance becomes cyanosed from the
stagnation of the circulation and lessened oxidation ; there
are serous effusions into the peritoneal, pleural, and pericardial
sacs and general oedema of the subcutaneous tissue and skin.
The mucous membrane of the gastro-intestinal tract is swollen
and redematous.

Pericarditis.

Inflammation of the pericardium may be a primary affection,
occurring in connection with rheumatism and Bright's disease,
and various acute infectious fevers, as pneumonia, typhoid,
scarlet fever, influenza, and puerperal septicaemia; or much
less frequently it may be a secondary affection resulting from
the extension of an inflammatory process from neighboring
structures to the pericardium.

The membrane first becomes dull and lustreless. The
character of the exudate varies, usually purely serous, but
sometimes hemorrhagic or seropurulent. The opposed sur-

ARTERITIS. 327

faces of pericardium often look as if the two layers had rubbed
together, while the more or less marked deposit of fibrin was
still in a soft plastic condition, giving them a rough, ragged,
or hairy appearance, suggesting the term "cor villosum."

The parietal and visceral layers may become agglutinated,
constituting what is known as adherent pericardium, which
may lead to hypertrophy of the heart, by reason of the in-
creased work thus imposed upon it.

Sclerotic areas, known as white spots, or milk-spots, are
probably the result of a chronic localized inflammation ; they
are noted in about 50 per cent, of all post-mortems. They
may be quite small, or large enough to cover the anterior sur-
face of the heart. They occur most frequently on the right
ventricle, next on the left ventricle, near the apex, and also
on the posterior surface of the heart, near its base. They are
formed simply of dense connective tissue, covered by endothe-
lium. Their exact significance is not fully understood.

THE BLOODVESSELS.

DEGENERATIONS.

Fatty degeneration : Not infrequently there are seen in the
aorta and other parts of the arterial system yellow spots or
streaks slightly raised above the internal surface ; under the
microscope it is found that the endothelial cells of the intima
have undergone fatty degeneration. The degeneration may
involve also the muscle-cells of the media. The affected areas
may soften and small superficial erosions result.

Calcareous infiltration most frequently affects the middle
coat of the artery, occurring by preference in vessels of me-
dium size. The greatly increased rigidity of the radials, often
noted clinically, is generally due to this cause.

Amyloid degeneration usually begins in the capillary walls
of the organ affected. The entire wall is involved.

ARTERITIS.

Acute inflammation of the walls of an avtery, independent of
any neighboring inflammatory process, is very rare.

328 DISEASES OF THE CIRCULATORY SYSTEM.

Chronic arteritis, atheroma, or arterio-sclerosis, however, is
of frequent occurrence. The aorta alone may be affected, but
more commonly the whole arterial system is more or less uni-
formly involved ; the veins even may be involved ("angio-
sclerosis "). It is usually associated with sclerotic changes in
the heart and internal organs, and seems to be dependent upon
the same causes — syphilis, gout, rheumatism, lead-poisoning,
chronic alcoholism, Bright's disease, and old age. It some-
times follows acute infections, as typhoid and scarlet fever,
and occasionally seems to be dependent on the cachexia of
cancer and tuberculosis.

In the aorta at an early stage of the process there are pale
pinkish, rounded, or oval patches or nodules beneath the
smooth and unaltered intima, varying in size from a mere
point to half an inch in diameter. On cutting into one of
these patches it is found to be firm and fibrous ; in the centre
there may be a yellow focus of fatty degeneration. Micro-
scopically the patch is composed of dense fibrous tissue which
seems to have been produced by a proliferation of the subendo-
thelial connective-tissue cells ; at first many round, oval, and
stellate cells can be readily seen, but later the structure of the
affected area may be quite indefinite from advancing fatty
degeneration. The calcareous plates often met with in the
aorta are the result of the infiltration of such patches with
the salts of lime ; these plates may be so numerous as to alter
completely the appearance of the vessel.

In the smaller vessels the changes are somewhat different.
Similar patches of opaque and firm tissue, one-sixth to one-
third of an inch in length, may occur at irregular intervals
along the course of the vessels. On cross-section of the artery
its lumen is seen to be considerably encroached upon at one side.

In other cases — endarteritis obliterans — these patches are en-
tirely absent ; the lumen of the vessel is uniformly encroached
upon, sometimes almost obliterated by the increased thickness
of the intima produced by an active proliferation of the endo-
thelial and subendothelial connective-tissue cells. The muscle-
fibres of the media are atrophied, and there is usually a marked
thickening of the adventitia, the result of a round-celled in-
filtration which becomes more or less fully developed into
fibrous tissue.

ANEURISM. 329

Serious consequences may follow these changes in the arterial
walls. In the coronary arteries the obstruction of the circu-
lation may be the immediate cause of fatty degeneration of
the heart-muscle and death. In the brain the anaemia result-
ing from such an obstruction may result in areas of softening.
In the aorta, aneurismal dilatation is a frequent result. The
heart is generally hypertrophied in consequence of the obstruc-
tion to the circulation offered by the thickened and rigid
arterial walls.

Aneurism.

An aneurism (Fig. 145) is a localized dilatation of an artery,
resulting from any cause which weakens its walls — as arter-
itis and injury, and from increased arterial pressure. Aneur-
isms may be classified according to their shape into fusiform,
cylindrical, and saccular.

In fusiform and cylindrical aneurisms there is a general dila-
tation of all the coats of the artery. A cirsoid aneurism is one
in which the vessel is rendered tortuous and convoluted as the
result of its elongation and unequal dilatation of different
parts.

In sacculated aneurisms, the most important variety, there
is a unilateral dilatation of the vessel. First, the media gives
way, and then there is a dilatation of the intima and adven-
titia, and thus is formed a sac which communicates writh the
artery by a narrow opening. As the sac increases in size it
may finally rupture. The blood may be retained subsequent
to rupture by the surrounding tissues ; the term false aneurism
is used to designate such a cavity, communicating with an
artery and containing blood, the walls of which are not formed
by the coats of the vessel. A dissecting aneurism is one in
which rupture of the intima occurs and the blood burrows a
false passage between the coats of the artery.

The results of the continued presence of the aneurism may
be extensive necrosis of neighboring tissues. Erosion of the
vertebrae and pressure of the aneurism on the spinal cord have
been the unsuspected cause of a paraplegia. In a similar
manner the sternum and ribs may be eroded and the aneurism
project beneath the skin.

330 DISEASES OF THE CIRCULATORY SYSTEM.

FIG. 145.

Aneurism of the ascending aorta (woman, agred 30). A, aorta ; B, orifice of commu-
nication ; C, aneurismal sac; D, rib adherent to the sac; E, shrunken aortic
valves (Ziegler).

PHLEBITIS.

Acute inflammation of a vein occurs either in connection
with the formation of a thrombus — thrombophlebitis, or is
associated with an inflammatory process in surrounding tis-
sues, which may produce thrombosis also, secondarily.

PHLEBITIS. 331

Chronic phlebitis may occur in association with arterio-
sclerosis, the changes being of the same character, but rarely
so marked. Calcareous infiltration of the affected areas is
much less common.

Varix is a dilatation of veins analogous to the aneurismal
dilatation of arteries. The essential factor in its production
is an increase in blood-pressure within the veins, as by passive
hypersemia due to heart disease, pressure of a tumor or the
gravid uterus.

The veins are not only dilated but elongated, and thus
become tortuous and convoluted ; the circulation through
them is greatly slowed, and it is not infrequent for thrombosis
to occur in consequence.

CHAPTER Y.

DISEASES OF THE RESPIRATORY ORGANS.

THE NASAL PASSAGES.

Acute rhinitis, or coryza, inflammation of the mucous mem-
brane of the nose, occurs most frequently as a simple "cold in
the head " due to exposure ; it may also accompany influenza,
measles, typhoid fever, and other infectious diseases. Diph-
theria may primarily involve, or extend to, the nasal passages.
The inflammatory hypersemia gives rise to a feeling of stuffi-
ness in the nose, and the subsequent exudation to the muco-
purulent discharge.

Chronic rhinitis supervenes as the result of repeated acute
attacks. The mucous membrane becomes thickened and the
nasal passages obstructed — hypertrophic rhinitis. Later there
may be complete atrophy of the mucous membrane ; in such
cases there is usually an extremely foetid, purulent discharge
— atrophic rhinitis or ozcena.

Syphilis may affect the nose, in the tertiary stage, in the
form of gummata, beginning in the mucous membrane,
periosteum, or perichondrium. There may be extensive nice ra-
tion and destruction of tissue, resulting in serious deformities.

THE LARYNX.

Acute inflammation of the larynx — laryngitis — may be due
to exposure to cold or inhalation of irritating vapors; and
accompanies measles, whooping-cough, smallpox, typhoid fever,
and other infectious diseases. In some cases there is such an
oedematous infiltration of the loose submucous tissue over
the aryepiglottic folds and at the base of the epiglottis as
to give rise to serious, even fatal, obstruction.

The severe inflammatory process excited by the diphtheria
bacillus is especially characterized by an exudate rich in
fibrin, which coagulates and adheres to the larynx as a grayish

332

THE BRONCHIAL TUBES. 333

or yellowish psendomembrane. Microscopically this pseudo-
membrane is found to consist mainly of the fibrillae of fibrin
and migrated leukocytes.

Chronic laryngitis may follow repeated acute attacks, or re-
sult from overuse of the voice ; or it may be secondary to dis-
eases of the nasopharynx. The mucous membrane is thick-
ened, due mainly to an increase of connective tissue, which is
characteristic of all chronic inflammations ; it has quite fre-
quently a granular appearance as a result of enlargement of
the racemose glands of the larynx, and often there are super-
ficial ulcerations or erosions.

Tuberculosis of the larynx is generally secondary to pulmo-
nary tuberculosis, occurring in about 30 per cent, of these
cases. The mucous membrane is thickened from the presence
of characteristic tubercles or a diffuse infiltration ; to this suc-
ceed caseation and ulceration, which may result in destruction
of the vocal cords.

Syphilis also may cause deep infiltrations, necrosis, and
ulceration ; secondarily serious deformities may arise from
contraction of the newly formed connective tissue.

Papillomata constitute more than one-half the tumors of the
larynx. They are especially common in people whose pro-
fession requires the constant use of the voice. They grow
most frequently from the squamous epithelium of the vocal
cords.

Epithelioma is the variety of cancer generally met in the
larynx. It appears first in the form of a nodular thickening
of the mucous membrane, which later undergoes ulceration.

Sarcoma of the larynx, which is usually of the spindle-
celled variety, is not of frequent occurrence.

The Bronchial Tubes.

Acute inflammation of the bronchial tubes — bronchitis —
results frequently from the extension of a simple inflamma-
tory process in the upper air-passages ; it is also almost a
constant manifestation of certain acute infectious diseases, as
typhoid fever, measles, scarlet fever, whooping-cough, and in-
fluenza. The larger and medium-sized bronchi are involved ;
in children, however, the terminal bronchioles and surround-

334

DISEASES OF THE RESPIRATORY ORGANS.

ing lung tissue, are specially liable to be affected, constituting
lobular or catarrhal pneumonia.

The mucous membrane of the bronchi is intensely red and
swollen. Upon the character of the inflammatory exudate

FIG. 146.

Catarrhal bronchitis, a, areolar tissue of the submucosa. infiltrated with serum
and leukocytes ; 6, alveolus of a mucous gland, infiltrated at the periphery by
leukocytes. The epithelium is undergoing colliquative necrosis, and in the
centre of the lumen are a few leukocytes with fibrin, c, c', blood vessels; c', shows
an infiltration of the wall by emigrating leukocytes ; d, muscularis mucosse ;
e, subepithelial areolar tissue of the mucous membrane, infiltrated with serum
and leukocytes; /, columnar epithelium of the surface in a state of colliquative
necrosis : g, exudate within the bronchus. In this portion of the bronchus the
destructive processes are so acute that the epithelium is destroyed, instead of
stimulated to the production of excessive mucus (Dunham).

depends the appearance of the sputum. At first it is a glairy,
tenacious fluid containing a few leukocytes — simply an exag-
geration of the normal secretion of the glands of the mucous
membrane. Later it becomes yellowish in color, muco-

FIBRINOUS BRONCHITIS. 335

purulent or purulent, and less tenacious, histologically resemb-
ling pus by reason of the large number of leukocytes present.
When the amount of this secretion is excessive, especially in
more chronic cases, the condition is known as bronchorrhoea ;
in some instances the odor of the sputum is very offensive —
foetid bronchitis.

Microscopically the bloodvessels are found to be dilated, and
surrounding them and infiltrating the walls of the bronchi are
numerous migrated leukocytes and young connective-tissue
cells. The epithelial cells of the mucosa are degenerated and
in many places desquamated (Fig. 146).

Chronic bronchitis occurs most commonly in the aged, who
are often predisposed by reason of a passive congestion of the
lungs, due to some form of cardiac weakness. It may follow
a neglected acute attack or gradually develop after repeated
subacute attacks. It is also frequently associated with
emphysema or other diseases of the lungs, with gout and
Bright's disease, and, in children, with rickets.

The bronchial walls are usually greatly thickened from new
connective-tissue formation in the outer fibrous coat. The
mucous membrane is generally atrophied ; the epithelial cells
are no longer columnar, but rounded or polygonal. In some
cases, however, the mucous membrane is swollen and hyper-
femic, and dotted with little gray points — the mucous glands,
which are greatly enlarged.

The cartilages of the bronchi and the muscular coat may be
so far supplanted by newly forming connective tissue as greatly
to weaken their walls. This in connection with increased
pressure from within, due to the increased expiratory efforts
of coughing, may cause fusiform or saccular dilatation of the
bronchi in places, bronchiectasis.

Fibrinous bronchitis is a variety of chronic bronchitis in
which there are expectorated at intervals, during months or
years, branching fibrinous casts of the bronchi of a lobe. The
exact pathology of the affection is not understood. Similar
casts of the larger tubes may result from an extension of a
diphtheritic inflammation of the larynx or trachea.

336 DISEASES OF THE RESPIRATORY ORGANS.

THE LUNGS,

ATELECTASIS.

Atelectasis is a condition in which the lung is compressed
or collapsed, so that there is an absolute absence of air from
the air- vesicles.

Congenitally it occurs, especially posteriorly and at the
base of the lungs, from some mechanical obstruction of the
air-passages, as the presence of meconium ; or an inability to
take a full inspiration, as the result of extreme weakness.
Under these circumstances the term apneumatosis is some-
times applied. The affected areas are bluish, and so solid
that if a portion is thrown into water it sinks.

Later in life a large pleuritic effusion, or a Avound in the
chest-wall, may result in the collapse of a whole lung. A
lobular collapse occurs in broncho-pneumonia, and is supposed
to result from a valve-like obstruction of a bronchiole by a
plug of mucus, which cannot be dislodged by inspiration, but
permits the air to escape from the lobules supplied. The
tissue is dry and tough, has a firm, flesh-like feel, does not
crepitate, and sinks if placed in water. If the condition per-
sists, there is finally an entire and permanent obliteration of
the air-vesicles by an overgrowth of connective tissue.

EMPHYSEMA .

Interstitial emphysema is a condition analogous to emphysema
of subcutaneous tissues ; there is an accumulation of air in
the connective-tissue septa between the lobules of the lung as
the result of rupture of an air-vesicle. It occurs most fre-
quently in the course of whooping-cough or broncho-pneu-
monia in young children ; and from excessive straining-efforts
in parturition, defecation, coughing, etc.

By vesicular emphysema we understand a dilatation of the
air-vesicles which occurs as the result of a weakened condi-
tion of the lung-tissue from inflammatory or degenerative
processes, lessening its ability to resist increased pressure
within, from such causes as chronic cough, blowing of wind-
instruments, etc. The lungs are considerably larger than
normal j there is a gritty feeling on section, and the dilatation

PASSIVE HYPER^EMIA. 337

of the air-spaces may be so great as to be apparent to the
naked eye.

Microscopically the air-vesicles are found to be rounded in-
stead of polygonal, and are increased in diameter. The

FIG. 147.

Section from an emphysematous lung (Ribbert). The pulmonary alveoli are en-
larged; their walls are stretched and thinned; atrophied because of repeated
excessive air-pressure within the alveoli. In more extreme cases of emphysema
the atrophy of the alveolar walls may lead to their total destruction in places,
so that the cavities of neighboring alveoli communicate. (Compare with Fig.
149.)

alveolar walls are thinned (see Fig. 147) ; and the bloodvessels,
being stretched over a larger surface, are narrowed, the
anaemia of the lung-tissue thus produced further favoring the
atrophy and degenerative changes in the alveolar septa. As
a remote consequence of the increased pulmonary blood -pressure
there is hypertrophy of the right heart.

PASSIVE HYPER^SMIA.

Passive hypersemia, brovm induration, or brown oedema, re-
sults from some obstruction to the outflow of blood from the
lungs, most frequently from some myocardial degeneration, or
valvular lesion, especially mitral; though it may occur in
connection with aortic stenosis, or regurgitation.

22-Hist.

338 DISEASES OF THE RESPIRATORY ORGANS.

The lungs are heavy and somewhat larger than normal.
On section they are dark red in color, and on pressure a
brownish-red serum exudes, frothy from admixture of air —
oedema. In other and more chronic cases the lung-tissue is
dry and indurated.

Microscopically, in cases in which the brown induration is
marked, there is considerable increase in the connective tissue
of the lung ; the pleura, interlobular septa, and alveolar walls
are thickened and pigmented. The alveolar walls have a
beaded appearance, due to the passive engorgement of the
capillary bloodvessels. Within the air-spaces are red blood-

FIG. 148.

Brown induration of lung, d, prominent capillaries in alveolar wall ; a, cells con-
taining pigment in lumen of alveolus; 6, c, alveolar epithelium. X 250
(Schmaus).

corpuscles, numerous leukocytes, and desquamated epithelial
cells — many of which contain pigment derived from the
altered red blood-corpuscles which they have englobed and
digested (see Fig. 148). Later, these cells having been taken
into the lymphatic system, the pigment is thus distributed.

(Edema of the lungs may also result from active congestion,
produced by inhalation of very hot or cold air, irritating
gases, etc. Microscopically the alveoli are found to contain a
few leukocytes, desquamated epithelial cells, and a granular
debris representing the coagulated serous exudate.

LOBAR PNEUMONIA. 339

HEMORRHAGIC INFARCT.

Infarctions are usually multiple, and occur in the centre of
the lower lobe, or near the root of the lung ; when superficial
they form a slight elevation beneath the pleura. They are
wedge-shaped, firm, brown in color, and are separated by a
distinct line of demarcation from the surrounding lung-tissue.

FIG. 149.

Hemorrhagic infarct of the lung (Kaufmann). The section contains a portion of
the plugged vessel beyond the site of the embolus. It and the pulmonary
alveoli are filled with blood, which, in the latter, has passed through the capil-
lary walls, rendered pervious by malnutrition. This blood may be derived
from the pulmonary vein and also from the bronchial artery, which communi-
cates with the capillaries of the alveolar walls.

Microscopically the air-spaces are found to be crowded with
red blood-corpuscles (see Fig. 149).

Pneumonia is the term employed to designate inflammation
of the lung, in contradistinction to inflammation of the bronchi
or pleura. Histologically and clinically there are several
well-defined varieties of pneumonia :

LOBAR PNEUMONIA.

Lofcar pneumonia is an acute, infectious, self-limited disease,
with a definite clinical course, and characterized pathologic-
ally by an extensive inflammation of the lung, involving an
entire lobe.

340 DISEASES OF THE RESPIRATORY ORGANS.

Etiology : The diplococcus pneumonice is found in the inflam-
matory exudates and in the sputum ; it is the micro-organ-
ism most frequently associated with the disease, though the
pneumococcus of Friedlander, streptococcus, staphylococcus,
typhoid bacillus, and bacillus of influenza seem to be capable
of producing similar lesions.

The lower lobe of the right lung is most frequently affected.

Division of process : The inflammatory process may be di-
vided into three stages : engorgement, red and gray hepati-
zation.

In the stage of engorgement, or congestion, the affected area
is deep red in color, crepitates less and is somewhat firmer
than normal, but is not solidified, does not sink if placed in
water ; the overlying pleura is dull and lustreless. On sec-
tion a bright red, frothy fluid exudes on pressure.

Microscopically the capillary bloodvessels of the alveolar
walls are greatly distended with blood and encroach some-
what upon the air-spaces, within which are a large number of
red blood-corpuscles, and a few leukocytes and desquamated
epithelial cells. A similar exudate is seen in the smaller
bronchi.

In the stage of red hepatization the inflammatory exudate
which has poured into the air-spaces has coagulated and com-
pletely solidified the lung-tissue, giving it a liver-like consis-
tency. On pressure the affected area does not crepitate, is
firm to the touch, yet friable, and if placed in water sinks.
It is swollen, and upon the external surface the ribs have left
an imprint. The pleura is often coated with a fibrinous exu-
date. On section the surface is bright red, smooth and
glistening ; later, as the fibrinous plugs within the air spaces
contract, the surface, especially if torn, has a granular appear-
ance, and with a little care the projecting alveolar plugs may
be lifted or scraped from the air-spaces, of which they form a
perfect mould.

Microscopically the air-vesicles are completely filled, even
distended, with the inflammatory exudate. The exuded blood-
serum has coagulated, and the fine fibrillse of fibrin entangle
within their meshes a large number of red blood-corpuscles
and migrated leukocytes and a few epithelial cells derived
from the swollen and proliferating epithelium of the alveolar

LOB AM PNEUMONIA.

341

walls. The exudate in the bronchioles and on the pleural
surface is composed of similar elements. The capillary blood-
vessels of the delicate walls of the air-spaces are much less

FJG. 150.

Section from lung in the second or exudative stage of croupous pneumonia, a, en-
dothelial wall of a small vein : 6, blood within the vein, unusually rich in leu-
kocytes, which have collected during the slowing of the circulation. The line
6 points to the nucleus of a leukocyte. Part of the blood has fallen out of the
section during its preparation, c, leukocytes beneath the endothelium of the
vascular wall; d, oedematous fibrous tissue surrounding the vessel. The fibres
of the tissue have been separated by the exuded serum. This tissue is also
moderately infiltrated with leukocytes that may have passed through the walls
of the vein, and contains a few red blood-corpuscles, e, wall separating two
pulmonary alveoli. This is also somewhat infiltrated with leukocytes. /, exu-
date within an alveolus, consisting of serum, fibrin, leukocytes, and red blood-
corpuscles ; it also contains a few epithelial cells desquamated from the alveolar
wall, g.

prominent than in the first stage, but are surrounded by
migrated leukocytes and proliferating connective-tissue cells,
forerunners of the hyperplasia of connective-tissue which
occurs in some chronic pneumonic processes (see Figs. 150
and 151).

In the stage of gray hepatization the lung- tissue still re-
mains solid, but becomes mottled in appearance, and finally
a uniform gray in color.

Microscopically it is found that the red blood corpuscles
have become decolorized or have disappeared, and the fibrin
filaments are broken down and granular. The exudate does

342 DISEASES OF THE RESPIRATORY ORGANS.

not now entirely fill the air-spaces ; it is composed mainly
of leukocytes, which have greatly increased in number and
are now undergoing a fatty degeneration (see Fig. 152).

If the patient survives, the inflammatory process may
terminate in resolution, abscess formation or gangrene.

FJG. 151. .

Croupous pneumonia— red hepatization. Three alveoli filled with fibrinous ex-
udate. In the latter a mesh-work of fibrin (/), desquamated alveolar epithelium
(e), leukocytes (I), and red blood-corpuscles, a, alveolar septa with capillaries.
X 250 (Schmaus).

Resolution is the most frequent termination, and is brought
about by a fatty degeneration and liquefaction of the exudate,
which is finally absorbed by the lymphatics, or expectorated.

Abscess-formation as the result of secondary infection with
pyogenic micro-organisms is a rare termination. It occurs
most frequently in the upper lobes.

Gangrene also is a rare termination. It is especially liable
to occur in the drunkard, and in cases in which the circulation
is exceedingly weak.

Associated lesions : Although the inflammatory process in
the lungs is the characteristic feature of lobar pneumonia, not
infrequently there are widespread pathological changes due to
the general systemic intoxication. Circulatory failure due to

LOEULAR PNEUMONIA.

343

degenerative changes in the myocardium is the most frequent
cause of death.

FIG. 152.

Croupous pneumonia — gray hepatization — showing the large accumulation of cellu-
lar elements within one of the pulmonary alveoli, which in some parts have
undergone such extensive fatty degeneration that their distinctive outlines are
no longer visible. X 200 (Green).

LOBULAR PNEUMONIA.

In lobular or bronchopneumonia the inflammatory process
does not involve large areas of lung-tissue, though the coales-
cence of the smaller lobular areas of consolidation, which are
more or less widely distributed throughout both lungs, may
simulate a lobar pneumonia.

Etiology : Lobular pneumonia may be a primary affection ;
but it is much more frequently secondary, occurring in the
course of influenza, wThooping-cough, measles, and other infec-
tious diseases. In animals it can be experimentally produced
by causing them to inhale steam or other irritating vapors;
or by section of both vagi — the glottis being rendered insen-
sitive, saliva and portions of food carrying harmful micro-
organisms are brought to the finer bronchi by inspiration.

344 DISEASES OF THE RESPIRATORY ORGANS.

Bacteria play an important part in the production of
catarrhal pneumonia, though no one organism is recognized
as the specific cause. In a large percentage of cases FriinkePs
pneumococcus is found.

Lesions: The inflammatory process seems always to begin
in the terminal bronchioles, and to extend by contiguity and
continuity to surrounding lung-tissue.

Scattered through both lungs there is a variable number
of solid patches, some of which are due to collapse of the air-
vesicles, while some are the result of inflammatory exudation.
The collapsed areas vary from one -tenth to one-fifth of an
inch in diameter, and are depressed below the surface of the
lung-tissue. The pneumonic patches vary from the size of a
pea to that of a hazelnut or walnut, and are raised above the
surface ; the overlying pleura may be somewhat opaque from
inflammatory exudation ; the surrounding pulmonary tissue
is often more or less emphysematous.

As a whole the lungs are congested but crepitant ; the solid
patches, however, are airless and sink in water. On section
the areas of collapse are found to be more or less conical in
outline, with the apex directed toward the bronchi with which
they are connected. The pneumonic patches are soft and
friable, at first dark red, and later grayish-yellow in color ;
they are not separated by a sharp line of demarcation from
the surrounding tissue. By the coalesence of such patches
nearly a whole lobe may be involved, in which case it is often
difficult to distinguish from the consolidation of a lobar
pneumonia. The cut surface of such an area is smooth, how-
ever, not granular ; irregular in outline ; and there are
neighboring smaller areas which have not as yet become fused
to the larger one.

The inflammatory process is sometimes divided into two
stages, red and gray splenization. corresponding to red and
gray hepatization of the lobar variety.

Microscopically , in the early stage of red splenization, if a
single lobule is examined, we note in the centre a small
bronchus with infiltrated, thick walls ; its lumen may be
filled with leukocytes and desquamated epithelial cells. The
interlobular connective tissue and alveolar walls are also
infiltrated and thickened by proliferating connective-tissue

CHRONIC INTERSTITIAL PNEUMONIA. 345

cells and migrated leukocytes. The air-spaces immediately
surrounding the bronchus are filled with a fibrillary network
of fibrin, a variable number of red and white blood-corpus-
cles, and epithelial cells. A little further from the bronchus
the air-spaces contain only the large, flat, rounded or oval cells
derived from the proliferating epithelium which lines the
alveolus.

In the later stage of gray spleiiization there are fatty degene-
ration and liquefaction of the alveolar exudate, part of which
is finally expectorated and part absorbed by the lymphatics.

Resolution is the usual termination. With the absorption
of the alveolar exudate the round-celled infiltration of the
walls disappears ; the whole process takes much longer, how-
ever, than in lobar pneumonia.

CHRONIC INTERSTITIAL PNEUMONIA.

Chronic interstitial pneumonia, or fibrosis, is characterized by
an excessive formation of new fibrous tissue, involving the
alveolar walls and the supporting connective-tissue frame-
work of the lungs. It may be secondary to lobar or lobular
pneumonia, or due to the inhalation of solid irritating patches
— pneumokoniosis.

The affected lung is generally smaller than normal, and
feels firm, fibrous, and elastic ; bronchiectatic cavities are fre-
quently met. When due to the inhalation of particles of coal
or carbon — anthracosis — the lungs are deeply pigmented ;
similar lesions occur in artificers in iron and steel — siderosis —
only the coloration is brown instead of black ; silicosis is the
term applied to an analogous condition in quarry men, in
which the lungs have a marble-like or slate-like appearance,
produced by inhalation of the dust-particles of dry silicious
stone.

Microscopically there is noted thickening of the pleura,
the interlobular septa continuous with its deeper layer, the
peribronchial and peri vascular tissue, and the interalveolar
septa. The air-vesicles are compressed, their walls thickened
and fibrous (Fig. 153). Following lobar pneumonia, cases
have been described in which, in addition to the thickening
of the walls of the air-spaces, there was organization of the

346

DISEASES OF THE RESPIRATORY ORGANS.

alveolar exudate in places; appearing even a few days after
the onset of the disease, were intra-alveolar plugs of newly

FIG. 153.

<**' •••

Interstitial pneumonia (from a case of unilateral " cirrhosis" of the lung). The
bronchi were much dilated, and there was a complete absence of any caseous
change. The drawing shows the new fibre-nucleated growth both in the alveolar
walls and in the interlobular tissue, also the pigmentation. At a a divided
vessel is seen. With a higher power a delicate reticulum is visible between the
cell-elements. X 100 (Green).

formed fibrous tissue, well supplied with bloodvessels com-
municating with those of the alveolar walls.

GANGRENE.

Gangrene of the lungs occurs as the result of obstruction
of the pulmonary or bronchial arteries, and in the course of
typhoid and other infectious diseases. It may follow a pneu-
monia ; result from a wound of the lungs ; or be due to press-
ure, as by an aneurism or by some foreign body in a bron-
chus. It may also result from the extension of necrotic proc-
esses from neighboring structures. There are two varieties :
the circumscribed and the diffuse.

In the circumscribed variety there are usually one or more
small foci in each lung, blackish, even greenish in appearance.
These foci have a most offensive odor, are soft and pultaceous,
and are surrounded by congested or hepatized lung-tissue.

Diffuse gangrenous areas may result from the coalescence

TUBERCULOSIS OF THE LUNGS. 347

of smaller foci, or may be diffuse from the first and involve
even an entire lung.

The sputum is usually intensely foetid.

THE INFECTIVE GRANULOMATA.
TUBERCULOSIS OF THE LUNGS.

The pathological changes in the lungs produced by the
tubercle bacillus vary somewhat with the different modes of
infection, whether through the respiratory passages, the blood
or lymph channels ; also with the number and virulence of the
bacilli, and more especially with the ability of the patient to
withstand their invasion. This last depends not only on the
state of one's general health, but also on one's inherited ten-
dencies toward the disease, the importance of which cannot be
overestimated. Just what is transmitted to an individual
who inherits a predisposition to tuberculosis cannot be stated
further than that there is a soil markedly favorable to the
growth of the germ.

Besides the characteristic lesion — the histological tubercle
— which is distinctive of the pathological changes produced
by the tubercle bacillus, these organisms are capable of excit-
ing tissue-changes quite similar to those of ordinary simple
inflammation. As in simple inflammations, the more intense
the irritant the more prominent the phenomena of cellular and
serous exudation, while in inflammations of longer duration
and less intensity the characteristic feature is the tendency
toward organization and production of new fibrous tissue; so
some tubercular inflammations are characterized by exudations
and others by proliferative changes.

When the bacilli gain access by, and are distributed through
the medium of the bronchial tubes in large numbers, the lesions
are not so sharply circumscribed as they are when the organ-
isms are deposited from the bloodvessels here and there in the
pulmonary tissue in small numbers • nor are they of the same
productive type, but are characterized by more extensive
exudation and a greater tendency to coagulation-necrosis,
caseation, and the involvement of larger areas.

In the bronchogenic tubercular inflammations of the lungs,
in some instances there is a tendency for the areas of pneu-

348 DISEASES OF THE RESPIRATORY ORGANS.

raonic consolidation to conform to the distribution of the
smaller bronchi — histologically the alveolar exudate resembling
that of lobular pneumonia ; in others there is a diffuse hepatiza-
tion of one or more entire lobes, the exudate consisting of fibrin,
leukocytes, and epithelial cells, as in lobar pneumonia.

To those cases in which there is extensive pneumonic con-
solidation and subsequent caseation and destruction of lung-
tissue the term phthisis pulmonalis is often restricted. Origi-
nally the term was employed to designate a wasting of the
whole body associated with disease of the lungs. The
pulmonary lesions, later recognized as characteristic of such
cases, were both " ulcerative " and nodular ; gradually, how-
ever, smaller nodules — tubercles — were noted, and finally
regarded as the starting-point of the older destructive lesions.
In its modern acceptation the term phthisis has come to be
used in connection with the wasting or destruction of the lung-
tissue rather than with the general wasting and emaciation of
the whole body; so wre find most authors describe separately
phthisis pulmonalis and miliary tuberculosis.

In these bronchogenie forms of pulmonary tuberculosis the
factors concerned in the production of a lobular distribution
and catarrhal exudation at one time, and a lobar distribution
and fibrin cms exudate at another, may not be understood ; the
character of the associated secondary infection is, however,
quite possibly one explanation. The histological tubercles
which are often noted in connection with these pulmonic con-
solidations, especially at their borders, might be assumed to
be due to the penetration of stray individual organisms between
the epithelial cells to the perialveolar and peri bronchial con-
nective tissues. These pneumonic consolidations most fre-
quently begin in the apices of the lungs, probably as the result
of some impairment in the nutrition of the lung-tissue at this
point, by reason of lessened aeration of the blood due to
diminished range of the respiratory movements at the apices ;
general feebleness and cardiac weakness still further favoring
the same results.

It has been stated that when the tubercle bacilli are
deposited in small numbers in the pulmonary tissue from the
bloodvessels, the lesions are different from those produced by
the entrance of large numbers through the respiratory pas-

ACUTE MILIARY TUBERCULOSIS. 349

sages. It might be assumed that where each organism is
deposited from the blood there results the accumulation of
epithelioid and lymphoid cells, with possibly a giant-cell in
their centre, which constitutes the typically histological
tubercle ; and that the " system " of such histological tubercles,
of which even the smallest gray miliary tubercle visible to the
naked eye is formed, results from the presence of as many
organisms. Secondarily are noted the exudations into the
surrounding air-spaces. The conditions which hold in the
lungs differ from those in other organs of the body on account
of the accessibility of the former not only to the tubercle
bacilli in larger numbers, which is regarded as an explanation
of the greater prominence of inflammatory exudations, but
also to streptococci and other secondarily infecting organisms,
which play a most important part in pulmonary tuberculosis.

Acute Miliary Tuberculosis.

Acute miliary tuberculosis occurs usually as part of a gene-
ral miliary tuberculosis, which not infrequently results from
the rupture of some tubercular focus — such as a caseous
lymph-gland — into a bloodvessel ; or follows operations upon
tubercular joints or bones. Clinically the disease has always
had a peculiar interest on account of its resemblance to
typhoid fever at certain stages.

The lungs are congested and studded throughout with small
grayish, gelatinous-looking nodules about the size of millet
seeds or small shot; at first they may be so small and trans-
lucent as to be scarcely visible to the naked eye, though
finally becoming quite large, especially in the lungs of chil-
dren. They may be widely separated or so closely set as to
solidify the whole lung. Some may be yellowish from ad-
vancing caseation. Microscopically it is noted that these
nodules are situated in the intorlobular or interalveolar septa,
and are composed of several histological tubercles (Fig. 154).
In these acute processes giant-cells are not often seen, the
centre and often the entire tubercle being caseous. The sur-
rounding air-spaces may be more or less completely filled
with inflammatory exudates, and the interalveolar septa con-
siderably thickened.

350 DISEASES OF THE RESPIRATORY ORGANS.

In more chronic cases, in which perhaps the bacilli are less
virulent or are admitted more slowly to the lungs, the nodules
are larger and not so numerous ; the areas of caseous degen-
eration are much more extensive.

FIG. 154.

Acute miliary tuberculosis of the lungs, a, a1, a2, a3, tubercles with central caseation,
in part in parenchyma on alveolar tubes (b, bl), in part situated on bloodvessels.
In many tubercles giant-cells. X 40 (Schmaus).

Acute Phthisis.

As has already been pointed out, the main features of
phthisis are the lobar and lobular consolidations, which are
wont speedily to undergo caseation. The size of these pneu-
monic areas may vary greatly.

In the earlier stages grayish miliary patches, one-twelfth to
one-sixth of an inch in diameter, stand out prominently be-
neath the pleura or upon the congested cut surface of the
lungs, in greatest number at the apices. Microscopically the
patches are found to have each a caseous centre, which is
structureless and granular in appearance — the outline of the
air-spaces may, however, be faintly discernible; further away

ACUTE PHTHISIS.

351

from this central zone the alveoli are filled with catarrhal or
fibrinous exudations (Figs. 155 and 156). Near the centre
of the patch may be noted a bronchiole, its lumen filled with
desquamated epithelial cells and a granular debris. The walls
of the air- vesicles and bronchioles are infiltrated and somewhat
thickened.

At a later stage these areas of consolidation reach the size
of a hazelnut or walnut, or they may involve an entire lobe or
even the whole lung. Although such a diffuse consolidation

FIG. 155.

A small soft gray tubercle from the lung in a case of acute tuberculosis. The whole
of the tubercle is shown in the drawing, and is largely constituted of intra-
alveolar products. X 100, reduced to £ (Green).

may appear quite as uniform as that of lobar pneumonia, mi-
croscopically there is usually evidence of an original lobular
character of the inflammatory process.

On section the surface of the affected areas, which have
become yellowish in color as the result of extensive caseation,
is generally smooth, though it may have a granular appear-
ance when the character of the inflammatory exudate is fibrin-
ous. The lungs may be fairly riddled with small, irregular

352 DISEASES OF THE RESPIRATORY ORGANS.

cavities with cheesy walls, resulting from the breaking down
and evacuation of the caseous material. The pleura is gener-
ally thickened, especially over the apices.

Microscopically it is noted that the areas of consolidation
are formed of the smaller patches just described, each with a
caseous centre and an outer zone of air-spaces filled by inflam-
matory exudations. The peribronchial connective tissue and
alveolar septa are infiltrated as in lobular pneumonia, and
occasionally typical histological tubercles may be seen here
and there, especially at the periphery of the pneumonic areas.

FIG. 156.

Section of lung from a case of acute phthisis, showing that the consolidation con-
sists almost exclusively of products accumulated within the alveoli. In some
parls a free space is seen between the alveolar walls and their contents; this
is due simply to the shrinking of the latter caused by hardening of the speci-
men. X 50 (Green).

Besides the cases whicli conform to a lobular type of pneu-
monia, others have been described which resembled lobar
pneumonia, not only in the character of the inflammatory
exudate, but also in its lobar distribution. In some instances
of acute phthisis, tubercles may be entirely absent, or at least
indistinguishable in consequence of the extensive caseous de-
generation; though they can generally be found, if not in the
lungs, on the pleura, or peritoneum, or elsewhere.

CHRONIC PHTHISIS.

353

Chronic Phthisis.

Chronic phthisis is the common form of pulmonary tuber-
culosis. The primary lesions are generally found in the apices
of the lungs. In the great majority of cases the inspired air
is the source of the infection, though occasionally without
doubt the tubercle bacilli are introduced through the blood or

FIG. 157.

K 'Mig-r •

mm v

Wall of a tubercular cavity, c, cavity ; k, cheesy wall ; c', c", small recent cavi-
ties ; t, tubercle. To the left, fibrous tissue in which are, 6, bronchi ; g, vessels.
X 100 (Schmaus).

lymph channels — the further extension of the disease result-
ing from rupture of a caseous focus into a bronchus and aspira-
tion of the infected material into other parts of the lungs.

The lungs are firmly adherent to the chest-wall ; the pleural
cavities may be thus entirely obliterated. The pleurae are

23— Hist.

354 DISEASES OF THE RESPIRATORY ORGANS.

greatly thickened — even as much as a quarter of an inch at the
apices — and fibrous, and may be studded with gray gelatinous
nodules. On sections, most characteristic lesion is noted : the
cavity, which results from liquefaction of caseous areas (Fig.
157). They are most frequent in the upper lobes, and vary in
size from that of a hazelnut to that of a small orange, or even
much larger, and have glistening, firm fibrous walls. Espe-
cially numerous in the upper part of the lungs are noted
irregularly rounded, opaque, grayish or yellowish areas of
consolidation.

The histological changes are similar to those in acute
phthisis, except as modified by the longer duration of the
inflammatory process. In the centre of these areas the
tubercles cannot be distinguished on account of the caseous
degeneration which has taken place ; at the periphery, however,
they may be. Here and there are nodules which are found to
be composed of several histological tubercles. The centre of
such a system of tubercles is generally caseous, though it may
be firm and fibrous. These tubercles are situated in the inter-
alveolar and interlobular septa, and may be seen in various
stages of development. They are generally surrounded by
patches of catarrhal or fibrinous exudation.

Fibroid Phthisis.

In fibroid phthisis, which is the most chronic form of the
disease, the reparative efforts on the part of nature predomi-
nate over the destructive effects produced by the tubercle
bacilli. An area of caseation is often found to be surrounded
by a capsule of more or less fully developed fibrous tissue, and
thus its further extension is arrested. There is always an
especially marked increase in the amount of interalveolar and
interlobular connective tissue, which leads to extensive indu-
ration of the lung-tissue.

Tuberculosis is often engrafted upon simple chronic inter-
stitial pneumonia.

The complications of phthisis are numerous and important.
The pleura is nearly always implicated. In acute cases,
over pneumonic areas, it is usually the seat of a seropurulent
or fibrinous exudation, as in lobar pneumonia ; or a diffuse

SYPHILIS OF THE LUNGS. 355

acute inflammation may result from rupture of a tubercular
focus into the pleural cavity. In more chronic cases there
are almost constantly, extensive adhesions between the parietal
and visceral layers.

Extension of the tubercular process in the lung itself is
caused by the aspiration of material from caseous foci to
other parts. Sputum loaded with tubercle bacilli is very
apt to infect the upper air-passages, and, if swallowed, the
gastro-intestinal tract. A general miliary tuberculosis may
result from secondary infection of the blood — through tuber-
cular infiltration of the vessel- wall or rupture of a caseous
focus into its lumen.

Pneumothorax is due to perforation of the pleura. The
pleura is very liable to undergo necrosis at a given point as
the result of an underlying focus of caseation in which are
involved the bloodvessels which nourish it. If this occurs
before pleuritic adhesions have been formed, perforation occurs.
In this manner are explained many cases in which an acute
pleurisy seems to precede the development of the pulmonary
affection.

Fatal hemorrhage may result from erosion of one of the
branches of the pulmonary artery.

Anaemia, emaciation, and fever are constant accompaniments
of phthisis.

Widespread amyloid changes in the viscera are present in
a large number of cases.

SYPHILIS OF THE LUNGS.

Syphilitic inflammation of the lungs in adults is rare; though
gummata, appearing as grayish or yellowish rounded nodules,
are sometimes observed. They may undergo central necrosis,
and thus result in the formation of cavities.

In congenital syphilis there is sometimes a consolidation of
extensive areas of lung-tissue, to which the term white pneu-
monia has been given, on account of the pale and anaemic
appearance of the affected areas. Microscopically there is
noted a great increase in the connective tissue, as in chronic
interstitial pneumonia, and a catarrhal exudate within the
alveoli.

356 DISEASES OF THE RESPIRATORY ORGANS.

OTHER GRANULOMATA AND TUMORS.

Actinomycosis is a rare affection of the lungs which clini-
cally and pathologically may closely resemble tuberculosis.
There are nodules of lobular pneumonia varying in size from
that of a pea to a cherry, which later become confluent and
undergo softening, resulting possibly in cavity-formation.
Microscopically the fungus is readily recognized within these
areas and in the sputum.

Glanders also rarely affects the lungs, producing either dif-
fuse inflammation with abscess-formations or isolated charac-
teristic nodules which microscopically are found to consist of
masses of round cells.

In leprosy the lungs are frequently affected, the lesions
resembling very closely those of tuberculosis.

Tumors : Fibromata, lipomata, chondromata, sarcomata, and
carcinomata are sometimes observed in the lungs. Secondary
sarcoma is quite common, and occurs much more frequently
than primary. Secondary carcinoma is not so common as
secondary sarcoma.

THE PLEURA.

Hsemothorax is a term indicating blood in the pleural cavity.
It may result from rupture of an aneurism, or fracture of the
ribs or other injury to the chest.

Hydrothorax signifies a non-inflammatory accumulation of
serum in the pleural cavity. It is usually bilateral, occurring
in the course of a general dropsy due to some chronic heart
or kidney disease, or to changes in the composition of the
blood. A slight serous effusion is not infrequent just before
death. If the amount of the effusion is considerable, it may
greatly interfere with respiration.

Pneumothorax : Air alone is rarely present in the pleural
cavity. It is usually associated with a serous or purulent
effusion — hydropnetimothorax or pyopneumothorax. It may
result from traumatic rupture or penetrating wounds of the
pleura ; 90 per cent, of all cases, however, are due to pulmon-
ary tuberculosis.

PLEURITIS. 357

PLEURITIS.

Pleuritis, pleurisy or inflammation of the pleura, is nearly
always secondary to an adjacent inflammatory process, as
pericarditis, pneumonia, gangrene or tuberculosis of the lungs.
It may occur in the course of some general disease, as pyaemia,
septica3mia, typhoid fever, influenza, and other infectious dis-
eases, rheumatism, gout, and Bright's disease.

Several varieties are usually described according to the char-
acter of the inflammatory exudate : fibrinous, serofibrinous,
and purulent.

The fibrinous variety is generally confined to circumscribed
areas, though it may involve the entire pleura on one side.
At first the membrane is congested and its normal glistening
appearance is lost, due to the cloudy swelling of the endo-
thelial cells, the exudations and other phenomena character-
istic of the early stage of inflammation. The serous exudate,
rich in fibrin, coagulates in the form of a thin white pellicle
on the surface, varying in thickness in different cases. Where
opposed surfaces have become agglutinated, on separation
there is often a shaggy appearance somewhat similar to that
produced by pressing together the buttered surfaces of two
pieces of bread — " bread-and-butter" pleurisy.

Microscopically may be noted the dilated bloodvessels, sur-
rounding which and infiltrating the connective tissue are
numberless migrated leukocytes. The thin pellicle on the
surface of the pleura consists of a delicate network of fibrin-
filaments, containing in its meshes migrated leukocytes, red
blood-corpuscles, and possibly a few desquamated endothelial
cells, resembling thus very closely the alveolar exudate in the
stage of red hepatization of pneumonia. At this stage opposed
pleural surfaces, which are found adherent, can readily be sep-
arated. Later, however, on this temporary scaffolding of
fibrin a new connective tissue is built, through the agency of
the leukocytes and proliferating endothelial cells, which
results finally in firm fibrous adhesions.

The serofibrinous variety may be simply a more advanced
stage of the inflammatory process. The quantity of the
serous exudate which accumulates in the pleural cavity varies
ereatly — it may exceed four litres.

358 DISEASES OF THE RESPIRATORY ORGANS.

Microscopically the serous exudate is found to contain a few
white and red corpuscles and desquamated endothelial cells.
In chemical composition and physical appearances it resembles
blood-serum. When the effusion is excessive the lung is
compressed against the vertebral column, airless and almost
bloodless.

Empyema: A purulent effusion into the pleural cavity
results either primarily from the presence of some pus-pro-
ducing micro-organism, or from secondary infection of a simple
serous effusion. The micro-organisms most frequently found
are the pneumococcus, streptococcus, staphylococcusand tuber-
cle bacillus; occasionally the bacillus coli, typhoid and others.
The pleura is greatly thickened, and on its surface are more
or less abundant granulations. A localized necrosis may
result in perforation of the pleura and discharge of the effu-
sion externally through the thoracic wall, into the lungs, or
through the diaphragm into the peritoneal cavity.

CHAPTER VI.
DISEASES OF THE GASTROINTESTINAL TRACT.

THE MOUTH.

To inflammation of the mucous membrane of the mouth
the term stomatitis is applied.

Catarrhal stomatitis is a simple inflammation unattended by
ulceration. It occurs most frequently in children, and results
from a great variety of causes, such as food which is too hot
or too cold, lack of cleanliness, etc. The mucous membrane
is congested and swollen, and either unduly dry or there is
an increased production of its mucous secretion.

Croupous or pseudomembranous stomatitis is nearly always
due to the extension of a similar inflammation in thepliaryrix,
produced by the bacillus of diphtheria.

Ulcerous stomatitis occurs most frequently between the ages
of four and ten years; though it may occur in adults in local-
ized epidemics, in camps and garrisons. Certain drugs, espe-
cially mercury, are capable of producing similar lesions. The
inflammatory process begins on the border of the gums
and extends to the lips, cheeks, and edges of the tongue. The
ulcers which form on the lips and cheeks may become quite
large. Suppuration and destruction of tissue around the
teeth may be so great that they finally become loosened and
fall out.

Aphthous stomatitis also occurs most frequently in children.
Bad hygiene, and debility resulting from prolonged illness, are
predisposing causes. It is characterized by the presence of
small yellowish-white patches (aphthce), lying on an inflamed
base, and varying in size from that of a hemp-seed to that of
a split pea. The lesion first appears as a small red papule with
a whitish centre. By the end of twenty-four hours this white
central area of degenerated epithelial cells involves the whole
patch. The inflammatory process seldom leads to liberation.

359

360 DISEASES OF THE GASTRO-INTESTINAL TRACT.

Gangrenous stomatitis, noma, or canerum oris, is a rare affec-
tion, characterized by a spreading gangrene of the cheek, gen-
erally involving one side only ; it is nearly always fatal. It
occurs most frequently in weakly, ill-nourished children,
especially after some exhausting acute infectious disease. The
earliest lesion usually noted is a sloughing ulcer on the inside
of the cheek, near the corner of the mouth. The mucous
membrane becomes black and gangrenous, and soon the proc-
ess involves the entire thickness of the cheek and extends in
all directions.

Thrush, or muguet, is a mycotic stomatitis, due to a fungus,
the oi'dium albicans, occurring especially in infants. It is
characterized by the presence of white patches, resembling
curdled milk, upon the mucous membrane. There is a ten-
dency for these patches to extend and involve the pharynx,
and even the gastro-intestinal tract. If a white patch is re-
moved, the underlying mucous membrane is red, eroded, and
may bleed. Microscopically the white deposit is found to be
composed of the delicate filaments of the parasite and degen-
erated epithelial cells.

All the infectious granulomata may affect the mucous mem-
brane of the mouth.

Tuberculosis is not often noted. It may be primary or sec-
ondary. The nodular masses undergo caseation, often result-
ing in the formation of ulcers closely resembling those of
tertiary syphilis.

Syphilis affects the mouth either in the form of mucous
patches in the secondary stage ; or gummata varying in size
from that of a pea to that of a hazelnut, in the tertiary. The
gummata may break down and leave deep ragged ulcers in
their site.

Tumors : Flat-celled carcinomata, epitheliomata, are of quite
frequent occurrence. They appear first as a small nodule, or
circumscribed infiltration, which soon tends to ulcerate and
spread rapidly.

Sarcomata usually affect the gums, sarcomatous epulis.

DIPHTHERIA. 361

THE PHARYNX.

Simple catarrhal inflammation of the pharynx, or simple an-
gina, is due to exposure to cold, or occurs in the course of
acute infectious fevers. A more chronic inflammation may
result from the excessive use of the voice, or be secondary to
some disease of the nasal cavities. The mucous membrane is
red and swollen. In some cases vesicles form, which burst
and leave behind small superficial erosions. Not infrequently
there are granulation-like projections above the surface of the
mucous membrane, due to hypertrophy, or distention of the
mucous glands, or to hyperpfasia of the lymphatic follicles.

At first the mucous membrane is thickened, but later it
often becomes atrophic.

Pseudomembranous pharyngitis is in most instances produced
by the Klebs-Loffler bacillus diphtherise. Lesions in every
other way similar are sometimes produced by other micro-
organisms, notably the streptococcus pyogenes. Such " diph-
theritic" pseudomembranes are especially frequent in scar-
latina and other acute infectious diseases, and may also follow
the application of various irritants to the mucous membrane.

Diphtheria is an acute infectious disease characterized by a
severe toxaemia, giving rise to an irregular fever, great pros-
tration, often followed by cardiac and other localized or gene-
ral paralyses ; and locally by the formation of a pseudomem-
brane at the point of lodgment of the diphtheria bacilli, either
on an abraded surface or a mucous membrane, generally that
of the pharynx and upper air-passages.

The pseudomembrane is grayish-white, later yellowish-
white in color. Small patches appear on the posterior pharyn-
geal wall, the tonsils, soft palate, or nares, which tend rapidly
to extend and coalesce, and thus may cover the whole pharynx ;
less frequently on the buccal walls, the oesophagus, stomach,
vagina, uterus, and on surface abrasions. The pseudomem-
brane is more or less adherent, and if removed a raw7 bleeding
surface may be left behind. The formation of this membrane
is the result of the severe inflammatory process set up by the
diphtheria bacilli. The serous exudate coagulates and entangles
the other inflammatory products. Microscopically it is found

362 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

to be composed of a network of fine fibrillse, in the meshes of
which are red blood-corpuscles, migrated leukocytes, des-
quamated epithelial cells, and masses of micro-organisms. The
underlying mucous membrane is congested and infiltrated with
leukocytes; its epithelial cells are undergoing granular de-
generation or coagulation-necrosis (Fig. 158).

FIG. 158

Edge of a diphtheritic membrane. Section from the human uvula (Ziegler). a,
normal stratified epithelium ; b, subepithelial fibrous tissue of the mucous mem-
brane ; c, epithelium that has undergone coagulation-necrosis. Only remnants
of cells remain in the coarse fibrinous meshwork. d, oedematous subepithelial
fibrous tissue containing fibrin and leukocytes ; e, bloodvessels ; /, hemorrhage ;
g, g, groups of the bacteria causing the necrosis.

The associated lesions are the result of the absorption of
toxins — the bacilli themselves do not gain entrance to the
circulation. The neighboring lymphatic glands are usually
greatly swollen ; «the kidneys are nearly always aifected, as
shown clinically by the albuminuria which is present in the
majority of cases — the renal epithelium becomes cloudy and
swollen, and minute hemorrhages are sometimes seen. Not
infrequently there are necrotic foci in the liver, and in nearly
all cases some myocardial degeneration. The diphtheritic
paralyses are due to degenerative changes in the nerve-centres
and peripheral nerves.

TONSILLITIS.

363

In tonsillitis the inflammation rnay be superficial and in-
volve only the mucous membrane of the tonsil as part of a
general pharyngitis. In other cases — lacunar or follicular
tonsillitis — it involves, in addition, the mucous membrane
lining the crypts, which become distended with inflammatory
products and project above the surface as small yellow spots.
The exudations at the mouth of adjacent lacuna? may coalesce,

FIG. 159.

FIG. 160.

Cicatricial stricture of oesophagus (War-
ren Museum).

A very tisht stricture of the oesophagus
of many years' duration, apparently
the result of chronic inflammatory
action; small abscess on the left
(Warren Museum).

and the resulting yellow patch somewhat resembles diphther-
itic membrane. Ulceration of the walls of the crypts may pro-
duce quite extensive destruction of tonsillar tissue. In other
cases the inflammatory process ends in the formation of an

364 DISEASES OF THE GASTEO-IXTESTINAL TRACT.

abscess — phlegmonous tonsillitis or quinsy — the tonsil becom-
ing so large as to project beyond the median line. The uvula
and epiglottis are often cedematous, and the submaxillary and
cervical lymphatic glands enlarged.

FIG. 161.

FIG. 162

Traction diverticulum which
was adherent to a cheesy
bronchial gland. The cut
shows the external oesoph-
ageal wall with the diver-
ticulum artificially distend-
ed (Warren Museum).

Congenital malformation
of the oesophagus. Up-
per portion ends in a
cul-de-sac ; the lower
portion opens into the
trachea (Harvard Med.
School, Warren Muse-
um).

Chronic hypertrophy may follow repeated attacks of acute
tonsillitis ; usually, however, it is associated with hyper-
trophy of the lymphoid tissue of the naso-pharynx — " aden-
oids." Microscopically there is noted an increase in the con-
nective-tissue stroma and of the lymphoid elements.

THE (ESOPHAGUS.

365

THE SALIVARY GLANDS.

Inflammation of the salivary glands may occur in the course
of various acute infectious diseases, as septicaemia, typhoid,
etc. ; or result from a special
infection, when it is known as FIG. 163.

mumps — the parotid gland being
most frequently affected.

Mumps rarely terminates in
the formation of an abscess in
the affected gland, while this is
the characteristic tendency in
the secondary infections, or
metastatic mumps.

THE (ESOPHAGUS.

Inflammation of the oesophagus
may be due to ingestion of acids
or alkalies, food or drink too
hot or too cold, the lodgment
of foreign bodies, etc. The in-
flammatory process may end in
ulceration and cicatricial stenosis
(Figs. 159 and 160).

Cylindrical dilatation of the
oesophagus results from long-
continued stenosis. Sacculated
dilatations result either from,
pressure from within or traction
from without, as by contracting
adhesions (Figs. 161 and 162).

Squamous-celled carcinoma is
the most frequent affection of
the oesophagus (Fig. 163). It generally occurs in the lower
third, though it may be found in any part, and gradually
produces a complete stenosis.

Cancer of oesophagus (Warden Mu-
seum).

366 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

THE STOMACH.

ALTERATIONS IN POSITION AND SIZE.

Gastroptosis, or total descent of the stomach, is the most fre-
quent displacement. It may be associated with similar dis-
placements of the other abdominal organs — enteroptosis, or
Glenard's disease.

Gastrectasia, or dilatation of the stomach, may result from
pyloric obstruction produced by the cicatrix of a healing
ulcer, carcinoma, pressure of a tumor, etc. ; or may occur in
consequence of simple atony of the muscular walls brought
about by overfeeding, inflammatory or degenerative changes.
The resulting stagnation of the stomach-contents leads to ab-
normal fermentations and a train of symptoms due to auto-
intoxication. When due to pyloric obstruction the dilatation
may be enormous. At first there may be compensatory hyper-
trophy of the muscle-walls of the stomach ; but later they
become thin and atrophied, and the mucous membrane non-
absorptive.

SIMPLE ACUTE GASTRITIS.

Simple acute gastritis is an exceedingly common condition.
In most cases it results from dietetic errors — excessive in-
dulgence, ingestion of food which has undergone partial de-
composition, or is too hot or too cold. It may also be pro-
duced by various chemical irritants, as arsenic, the iodides and
salicylates, even in therapeutic doses. The mucous membrane
is found to be congested, swollen, covered with a film of
glairy mucus, especially in the pyloric region, and punctated
here and there by small hemorrhagic patches. The gastric
secretion is reduced in quantity and quality, a fact first ob-
served by Beaumont, through a gastric fistula, in the case of
the Canadian, Alexis St. Martin. The clinical opportunities
for noting the marked change in the quality of the gastric
juice — the hypochlorhydria, etc. — are numerous, through the
use of the stomach-tube.

Microscopically both the parietal and the central cells of the
gastric tubules are swollen and granular ; the bloodvessels of
the interglandular connective tissue are distended and sur-

ACUTE TOXIC GASTRITIS. 367

rounded by migrated leukocytes. At a later stage the leuko-
cytic migration becomes more, marked, either as a diffuse
round-celled infiltration of the mucosa, and often also of the
submucosa, or confined to more or less sharply circumscribed
patches. The lymph-follicles are often hyperplastic.

PURULENT GASTRITIS.

Purulent or phlegmonous gastritis is a rare and almost in-
variably fatal affection. It occurs in the course of puerperal
fever, pyaemia, smallpox and similar infections ; or it may be
a primary condition. The inflammatory process is either cir-
cumscribed or diffuse. In the former case there is generally
but one abscess — most frequently situated near the pylorus,
and varying in size from that of a hazelnut to that of a goose
egg. In the latter case there is a diffuse purulent infiltration
most marked toward the pylorus, involving first the sub-
mucosa ; later the mucosa becomes riddled with perforations,
through which pus wells up. The muscle and serous coats
may be involved, and the serous surface covered with a puru-
lent exudation.

ACUTE TOXIC GASTRITIS.

Acute toxic gastritis, or gastritis venenata, results from the
ingestion of such poisons as alcohol, arsenic, phosphorus,
bichloride of mercury, organic and inorganic acids, and
caustic alkalies.

The lesions produced vary with the kind and quantity of
the poison taken and the length of time elapsing before death ;
they are associated with similar changes in the esophagus,
and, below the stomach, in the small intestine, even to the
ileocrecal valve.

The inflammatory process excited by dilute adds and alka-
lies may resemble that in simple acute gastritis. When con-
centrated they produce local death of the tissues ; and if the
patient survives, most serious deformities of the stomach
may result. The slough involves the mucosa and often also
the other coats of the stomach, frequently producing a perfo-
ration. Adjacent organs, especially the liver and spleen, are
often corroded and discolored in a like manner.

368 DISEASES OF THE GASTRO-INTESTINAL TRACT.

The sloughs produced by sulphuric and hydrochloric acids
are dry and brittle, and ashy-gray in color, or black and
charred in extreme cases ; those of nitric acid are yellow. The
surrounding tissue is the seat of an intense hemorrhagic in-
flammation. The sloughs produced by the caustic alkalies
are not brittle but soft, and have somewhat the appearance of
a soft membrane. Phosphorus, arsenic, and antimony in large
doses produce more especially a fatty and mucoid degeneration
of the epithelial cells of the gastric tubules, resulting in an
opaque, yellowish-white appearance of the mucous membrane.

CHRONIC GASTRITIS.

The systematic clinical use of the stomach-tube for the pur-
pose of obtaining the gastric secretions for study, within recent
years, has thrown much light upon the pathological physiology
of digestion. And the microscopical examination of pieces of
the gastric mucosa found in the washings from the stomach
has added greatly to our knowledge of the anatomical lesions
associated with the well-defined fundamental types of chronic
gastritis recognized clinically.

The character of the exciting cause seems to bear no relation
to the resulting lesion. Evidences of chronic gastritis are
found so frequently at autopsy that a terminal gastritis must
be looked upon as an almost constant accompaniment of the
final stages of all chronic diseases.

More or less pronounced inflammatory changes are asso-
ciated with organic lesions of the stomach, as ulcer and cancer.
They are secondary also to dilatation and atony of the muscle-
walls, and the irritation produced by the resulting stagnation
of the stomach-contents and abnormal fermentations which
take place. In fact, the possible causes of gastritis are so
numerous that it is surprising a normal stomach should be
found after middle life.

The most frequent causes of chronic gastritis as an inde-
pendent and primary affection of the stomach are dietetic —
not only improper food, but improper methods of eating it;
bolting the food, with insufficient mastication, and large
draughts of liquid which are often unduly hot or cold ; the
excessive use of condiments, etc.

GASTRITIS GLANDULARIS PROLIFERA. 369

Gastritis Mucipara.

As in acute gastritis, the changes are most marked in the
region of the pylorus. In early stages of the inflammatory
process there is a diffuse redness of the mucous membrane,
which later becomes a mottled pale gray. The mucosa is
swollen and covered by a tenacious layer of tough mucus.
Here and there are small cysts, produced by occlusion of the
gastric tubules. Occasionally it is studded with papillary
projections about the size of a pea. As in other chronic in-
flammations, there may be a marked increase in the connec-
tive-tissue stroma, wrhich results finally in atrophy of the gland-
ular tissue.

It is only on microscopic examination, however, that the
distinctive features of this variety of chronic gastritis can be
noted. The number of gastric tubules in a given field is
much less than normal. Most characteristic is the mucoid
degeneration of the chief and border cells of the tubules,
extending to the fundus of the gland. In addition to these
parenchymatous changes, there is a more or less pronounced
cellular infiltration of the interglandular connective tissue.
As would naturally be expected, the gastric secretions are
greatly reduced in quantity and quality, and in late stages
even entirely wanting.

Gastritis Glandularis Prolifera.

This variety of chronic gastritis stands in marked contrast
to the one just described. The distinctive feature here is the
proliferative activity of the chief and parietal cells lining the
gastric tubules, the parietal or acid-producing cells especially
being greatly increased in size and number and lying in close
juxtaposition. These oxyntic or parietal cells may also be
found in the tubules of the pyloric region, where they are not
normally present. In some cases there seems to be a pro-
liferation of the glandular tubules, the entire gland becoming
elongated and tortuous. There may be associated with these
parenchymatous changes more or less cellular infiltration of
the interglandular connective tissue.

The cylindrical surface-epithelium is often desquamated

24— Hist.

370 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

over quite extensive areas, and ulcer is not an infrequent com-
plication.

As might be expected, the secretory activity of the gastric
tubules is greatly increased. Not only is the quantity of the
gastric juice augmented, but it is much richer in pepsin and
hydrochloric acid.

Gastritis Glandularis Atrophica.

Gastritis glandularis atrophica may occur as a terminal
stage of other varieties of chronic gastritis, as a senile change,
or complicating various chronic diseases, and rarely as a
primary aifection. It is characterized by a degeneration of
both the cylindrical cells of the surface of the mucous mem-
brane and vestibular alveoli, and the cells lining the gastric
tubules. The former undergo a mucoid, and the latter a
granular and fatty degeneration. In the tubules it becomes
impossible, by reason of their loss of staining properties and
indistinctness of outline, to distinguish between the chief and
parietal cells.

Macroscopically the mucous membrane presents a smooth,
thin, white surface. In addition to the glandular elements,
the submucosa and muscular coats may be involved by the
atrophic changes, a thin layer of fibrous tissue taking the
place of the latter. In other cases a similar destruction of
glandular tissue is the result of a proliferation of the inter-
glandular connective tissue. Instead of a thinning of the
stomach-wall, it may be greatly thickened by an overgrowth
of connective tissue beneath the mucosa — often resulting in
great reduction of the size of the organ, even to a capacity
of a few ounces.

The natural result of these lesions is a total abolition of the
secretory functions of the stomach. In spite of this, however,
the patient may remain well nourished and free from other ill
consequences as long as intestinal digestion is normal. The
evil results produced are often alone due to a failure of such
compensation on the part of the small intestine.

A purely interstitial inflammation of the stomach indepen-
dent of lesions of the parenchyma is described by Hayem ; but

ULCER OF THE STOMACH. 371

clinically has no distinctive feature by which it can be
recognized.

ULCER.

Ulcer of the stomach may occur in the course of acute and
chronic gastritis; or independently ; not infrequently it is found
post-mortem when no symptoms had existed during life to
indicate its presence. It is stated that in 5 per cent, of
deaths from all causes either an open ulcer or a resulting
cicatrix can be found.

It is rare before the age of ten years, though it has been
met with in infants at birth ; it is much more frequent in the
female than male.

Circulatory disturbances — arteriosclerosis, thrombosis, and
embolism — are undoubtedly important etiological factors, as are
likewise general anaemia and malnutrition. The frequent asso-
ciation clinically of hydrochloric-acid superacidity — in 80 or
90 per cent, of cases — is suggestive of autodigestion, and it is
maintained by many that without this excessive acidity of the
gastric secretions ulcer does not occur. At least it must be
admitted that it could make the production of ulcer easier
when factors interfering with the nutrition of the stomach-
wall, at a given point, are present; and also might subse-
quently seriously interfere with the healing of such a lesion.
At first it was asserted by Rigel that this superacidity was
constantly present in ulcer. The small percentage of cases in
which it is not, might be accounted for by an associated gastritis
that has gone on to glandular atrophy. On the other hand,
it is intelligible that the superacidity may be excited by the
ulcer — in a manner possibly analogous to the hypersecretion
of tears produced by a corneal ulcer.

Trauma alone cannot produce gastric ulcer ; other factors
are necessary. It is generally conceded that gastric ulcer
artificially produced in lower animals heals promptly; and in
man pieces of the mucous membrane have been torn away by
suction of the stomach-tube, the lesion healing without the
formation of an ulcer. But if a high degree of anemia is
first produced in dogs by the gradual withdrawal of blood,
ulcers can be produced by various irritants, which heal very
slowly ; and so, clinically, ulcer is especially frequent in chlor-

372 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

otic young girls, in whom, in addition to the anaemia, a hyper-
chlorhydria is often present.

There is generally but one ulcer, though there may be
several, often developing successively.

FIG. 164.

Two ulcers in the small curvature of the stomach,
coat (Warren Museum).

FIG. 165.

formed by muscular

Perforating ulcer of the stomach (Warren Museum).

Gastric ulcers — macroscopic description: The lesion occurs
most frequently along the lesser curvature and on the posterior

ULCER OF THE STOMACH.

373

wall near the pylorus (Fig. 164). In size it varies from one-
quarter of an inch to four or five inches in diameter; generally,
however, from a half to two inches. In shape it is usually
rounded or oval, and has a characteristic punched-out appear-
ance, especially if the mucous membrane alone is involved.
If it is deeper, the excavation may be somewhat funnel-shaped
by reason of its sloping edges.

FIG. 166.

An ulcer of the stomach, showing at its base the open orifice of a vessel: death
from hemorrhage (Warren Museum).

If all the coats of the stomach-wall are involved, as often
happens, inflammatory adhesions may bind it to an adjacent
organ, as the liver or pancreas, which thus comes to form the
floor of the ulcer.

Microscopically, there is noted some round-celled infiltration
in the immediate neighborhood of the ulcer. The walls of
the adjacent bloodvessels are greatly thickened by an obliter-

374 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

ating endarteritis — a state of affairs which protects largely
against hemorrhage.

The dangers in gastric ulcer, which are always imminent,
are perforation and hemorrhage.

FIG. 167.

Hour-glass contraction of stomach (Warren Museum, Harvard Medical School).

Perforation (Fig. 165) and the escape of the stomach-
contents into the peritoneal cavity cause death immediately
from shock ; or in a few days from a general peritonitis. This
accident occurs most frequently when the ulcer is situated on

TUMORS OF THE STOMACH.

375

the anterior wall of the stomach. It may also take place into
the liver, spleen, or pancreas, with resulting abscess-forma-
tions; or into the pleura, pericardium, or lungs.

Hemorrhage, when a large vessel is eroded, may prove
rapidly fatal (Fig. 166).

Cicatrization and consequent contractions of portions of
the stomach-wall may cause considerable deformity — hour-
glass contraction, or pyloric or cardiac stenosis (Fig. 167).

TUMORS.

Carcinoma is the most common and most important tumor
of the stomach. It is almost invariably a primary affection.

FIG. 168.

'•

Cancer • a large fungous growth at the pylorus, with dilatation and hypertrophy of
the walls (Warren Museum).

Secondary cancer is rare, though it may result by extension
from adjacent organs ; and in a few instances there seems to

376 DISEASES OF THE GASTRO-INTESTINAL TRACT.

have been a direct implantation of cancer-cells upon the gastric
mucosa from a primary lesion above — cesophageal, lingual, or
facial.

It rarely occurs before thirty years of age, though in a few
instances it has been noted in infants. From the age of fifteen
years on, it rapidly increases in frequency, three-fourths of all
cases occurring between the ages of forty and seventy years.

FIG. 169.

Cancer of the cardiac end of stomach and oesophagus (Warren Museum).

In women, cancer affects primarily the stomach in 20 to
30 per cent, of cases ; aud in men in 40 to 50 per cent. In
about one-half the cases the neoplasm is situated at the pylo-
rus, the posterior wall and lesser curvature coming next in
frequency.

The position and shape of the stomach are often altered.

TUMORS OF THE STOMACH. 377

When there is pyloric obstruction its capacity may be greatly
increased (Fig. 168); or much diminished if such a con-
dition exists at the cardia, or if there is a diffuse carcinoma-
tous infiltration of the walls of the organ (Fig. 169). If
the pylorus is not supported by adhesions, it may sink to the
pelvis.

Metastases occur in one-half the cases ; the liver is in-
volved in over one-third of them. The neighboring lym-
phatic glands, especially those behind the lesser curvature of
the stomach, become converted into large cancerous nodules,
and the peritoneum is often involved by direct extension of
the tumor-formation.

Histologically several varieties of the neoplasm are recog-
nized :

Scirrhus is the most common, constituting about 75 per cent,
of the cases. There may be a ring-like contraction at the
pylorus, or a diffuse infiltration of the walls of the stomach
without any nodular prominences, which condition might be
confounded with a hyperplastic interstitial gastritis. Occa-
sionally small, flat nodules occur on the serous surface over
the region of the tumor. If the mucous membrane ulcerates,
which is rare, it is only superficial. Scirrhus is almost in-
variably situated at the pylorus.

Encephaloid grows very rapidly, and forms large, soft, gray-
ish-white, irregular, papillomatous masses, which project into
the cavity of the stomach. It is so prone to undergo necrosis
that it generally presents at the autopsy as a bowl-shaped,
ulcerating depression, with irregular, ragged walls of varying
height and thickness, formed by the surrounding tumor-mass.
Perforation may result from extensive ulceration.

Adeno-carcinoma in general appearance resembles encepha-
loid, and tends to undergo extensive ulceration in a similar
manner.

Squamous-celled cancer affects the region of the cardia, tak-
ing its origin from the flat cells of the resophagus.

Colloid carcinomata have a transparent jelly-like appear-
ance, due to the degenerative change they have undergone.
This degeneration may affect any form of cancer, but more
especially adeno-carcinoma.

378 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

THE INTESTINES.
Congenital Deformities and Displacements.

Absence of the whole, or large parts, of the intestinal tract
is sometimes met with in monstrosities. Lesser developmental
defects are not uncommon. The anus may be wanting —
imperforate anus — and likewise the rectum and lower part of
the colon. MeckeVs diverticulum (Fig. 170) is a remnant of

FIG. 170.

Meckel's diverticulum (Dennis).

the omphalo-mesenteric duct of foetal life. It is a cylindrical
appendage, of the same structure as the small intestine, and
arises from the latter, opposite the mesenteric attachment,
about a meter above the ileo-csecal valve. Such diverticula
are sometimes the cause of intestinal obstruction (Fig. 171).
The caecum and ascending colon are sometimes situated on

ACQUIRED DEFORMITIES AND DISPLACEMENTS. 379

the left side, and the descending colon and sigmoid flexure on
the right. The transverse colon may be entirely absent, the
ascending and descending colon lying side by side.

FIG. 171.

Internal strangulation by a diverticulum (Warren Museum).

Acquired Deformities and Displacements.

Hernia is a term by which is generally understood a pro-
trusion of the intestine through a natural but abnormally
dilated opening in the abdominal wall. It pushes in front of
itself the peritoneum, which thus forms the sac of the hernia.

Strangulation is the most serious result of hernia, and occurs
when the gut is so constricted or compressed that it is no longer

380 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

pervious. By reason of the interference with its blood-
supply, if the constriction is not relieved, gangrene sooner
or later ensues.

Volvulus is another frequent cause of intestinal obstruction.
There is either a twist of the bowel on its long axis, or, more
frequently, a loop of intestine is twisted around its mesenteric
attachment. The sigmoid flexure is the most frequent seat
of its occurrence.

Intussusception, or invagination, is more frequent in chil-
dren than in adults, occurring usually at the ileo-csecal valve.
One part of the intestine slips over another, the length of the
invagination, which is nearly always downward, varying from
a few inches to several feet (Fig. 172). Thus the caecum and

FIG. 172.

" • I —-*"••• ""••- . _'; ,;• ^.^"^

Ileo-csecal intussusception of minor degree. To the right is seen the appendix
vermiformis just about to be swallowed (Hutchinson).

lower part of the ileum may be pushed into the colon until
the ileo-csecal valve even reaches the rectum. Gangrene and
a fatal peritonitis are the usual termination.

Inflammations.

Inflammatory processes may involve more or less the entire
length of the intestinal tract — entero-oolitis — or be more par-
ticularly limited to one of its subdivisions, suggesting the
terms duodenitis, colitis, ileo-colitis, typhlitis, proctitis, etc.

Enteritis — inflammation of the small intestine — is an

ACUTE COLITIS. 381

exceedingly frequent affection, the most prominent clinical
feature of which is diarrhoea. The watery consistency of the
stools is due, not so much to the inflammatory serous exuda-
tion, as to the increased peristalsis, which permits of less time
for the abstraction of the fluid constituents of the intestinal
contents.

The inflammatory process is caused by improper food, espe-
cially that in which poisonous alkaloids have been formed
during putrefactive changes ; also by inorganic poisons, like
arsenic and antimony ; and it may occur secondarily in the
course of various infectious diseases.

Lesions : The mucous membrane is red and swrollen, often
covered with mucus; and here and there maybe small hemor-
rhagic spots. The solitary and agminated lymphatic follicles
are swollen, and appear as small, dull gray prominences upon
the mucous surface ; small pitted, so-called follicular ulcers
result if these lymphatic glands undergo necrosis. In severe
cases the raesenteric glands are enlarged. When the inflam-
matory process becomes chronic, the rnuscularis is in-
volved, as in gastritis, and often much hypertrophied. Some-
times polypoid elevations are produced by proliferation of
glandular elements. In the later stages there may be atrophy
of the mucous membrane alone, or involving, in addition, the
muscularis.

A duodenitis may be associated with an inflammation of the
stomach. It is exceedingly liable to produce an obstruction
of the common bile-duct by inflammatory swelling of the
mucosa and accumulation of mucus, thus giving rise to reten-
tion of bile and an obstructive or catarrhal jaundice.

Acute colitis is, in the great majority of instances, associated
with the condition recognized clinically as dysentery. Sporadic
cases result from ingestion of tainted food, from mercury and
other poisons. The infectious nature of the epidemic form
naturally suggests itself. The amoeba coli, a unicellular amoe-
boid body, measuring twenty to fifty microns in diameter, is
found not only in the stools, but also in the intestinal wall
adjacent to the dysenteric ulcers, and in the pus in hepatic
abscesses secondary to dysentery. Typical dysentery has

382 DISEASES OF THE OASTRO-INTESTINAL TRACT.

been produced in lower animals by the injection of dysenteric
stools into their intestines.

The severity of the lesions noted varies greatly. In mild
cases the mucous membrane is swollen and hypersemic, and

FIG. 173.

Appendix containing biliary calculus (Museum, Carnegie Laboratory). 1, biliary

calculus.

covered with tenacious mucus. The solitary follicles are
enlarged, and petechial hemorrhages are often seen. At a
later stage and in more severe cases these follicles undergo

ACUTE COLITIS.

383

necrosis ; the resulting ulcers may be superficial, or deep and
ragged in outline, spreading rapidly, so that there is but little
of the mucous membrane unaffected. In many cases the

FIG. 174.

Appendix containing two fecal concrements : case of perforative appendicitis, the
perforation opposite the distal concrement (Museum, Carnegie Laboratory).

mucous membrane is covered with a grayish or brownish
pseudo-membrane, either in isolated patches or less frequently
as a uniform coating — diphtheritic or croupous dysentery.

384 DISEASES OF THE GASTRO-INTESTINAL TRACT.

Fi«. 175.

Suppurative appendicitis, abscess of appendicular wall, perforation, localized sup-
purative peritonitis; 2, ruptured abscess of wall ; 3, extension of a suppurative
focus (Museum, Carnegie Laboratory).

Sloughs of varying depth and sometimes of very considerable
size may form, and, on separating, leave behind ragged ulcers.

APPENDICITIS.

385

Chronic inflammation may succeed the acute. In some cases
the inflammatory process is limited to the rectum — proctitis.
Appendicitis — inflammation of the vermiform appendix — is
now recognized as the cause of the set of symptoms which
were at one time attributed to inflammation of the caecum —
typhlitis. On laying open the appendix, faecal concretions
are sometimes found, to which an etiological significance has
been attributed (Figs. 173 and 174); but they are quite as

FIG. 1

Funnel-shaped csecum and appendix, gangrenous appendicitis : 1, fecal concre-
ment; 2, mesenteriolum ; 3, appendix, situated behind and to inner side of
caecum ; 4, ilio-csecal junction (Hartley).

likely the result as the cause of the condition, and formed by
accumulations of mucus, desquamated epithelial cells and
other inflammatory products. Undoubtedly the common colon
bacillus, which is normally present, plays an important part,
multiplying rapidly and gaining new virulence in the favor-
able nidus produced by the inflammatory process. The entire
wall of the appendix may be involved, or the lining mucous
membrane alone. Necrosis and ulceration may result

25— Hist.

386 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

perforation and localized purulent collections, or a general
septic peritonitis. Not infrequently the whole organ becomes
almost immediately gangrenous (Figs. 175 and 176).

Specific Inflammations of the Intestines.

Asiatic cholera is an acute infectious disease characterized
by an intense inflammation of, and a copious serous exudate
from, the small and large intestine ; due to the spirillum
cholera?, first described by Koch. Clinically, also, the main
features of the disease are referable to the intestinal tract, the
constitutional disturbances being due to the absorption into
the general circulation of toxins produced by the micro-
organisms there localized. The mucous membrane, particu-
larly in the lower part of the ileum, is swollen, congested, and
frequently the seat of ecchymoses ; the solitary and agminated
lymphatic follicles are often swollen, as may be likewise the
mesenteric glands. The bowel is distended as if paralyzed,
and filled, often with large quantities, of a serous transuda-
tion containing small white flakes of desquamated and de-
generated epithelial cells, similar to the characteristic " rice-
water" dejections.

Later in the disease, in some epidemics, the mucous mem-
brane may be ulcerated or covered by a pseudo-membrane,
the colon presenting an appearance similar to that in dysen-
tery— possibly the result of secondary infections. Outside of
the intestinal tract one of the most marked features of the
disease is the pronounced thickening of the blood due to the
enormous serous transudations.

The heart, liver, spleen, and kidneys may be the seat of
parenchymatous degenerations characteristic of other toxaemias
as well, however, and in no way distinctive of this disease.

Typhoid fever is an acute infectious disease produced by the
bacillus of Eberth, the characteristic lesions being almost
entirely confined to the lymphadenoid structures of the lower
part of the ileum and upper part of the colon. Contaminated
water or milk is the chief source of infection.

The morbid changes in typhoid fever may begin as a diffuse
inflammation of the intestinal mucosa, but almost immediately,
at least within twenty-four hours, the solitary follicles and

TYPHOID FEVER.

387

a quarter of an inch thick.

FIG. 177.

Swelling of Peyer's patches and solitary
glands of the intestine, as seen in
typhoid fever (Green).

Peyer's patches become infiltrated, intensely congested, swollen,
and project into the lumen of the intestine. The largest
patches may be as much as
The solitary follicles vary in
size from that of a pin point
to that of a pea (Fig. 177).
By the end of the first week
the number of patches and
follicles involved is about as
large as it will probably be-
come, and the stage of in-
flammatory infiltration and
hypet-plasia has reached its
height. These changes may
affect only a few patches and
follicles in the neighborhood
of the caecum or involve the
entire intestinal tract.

Generally the swollen solitary follicles are not so numerous
as the swollen Peyer's patches, though in some cases they are
more prominent, the patches being but little affected. Cases
of undoubted typhoid have been reported in which all intesti-
nal lesions were absent.

Resolution now slowly takes place through the absorption
of the inflammatory products ; or a greater or less number of

patches, according to the severity
of the case, undergo necrosis as the
result of interference with the blood-
supply by the pressure of the sur-
rounding excessive infiltration. The
patches become less congested, gray-
ish in color, with possibly a yel-
lowish or brownish necrotic centre.
When the slough separates there is
left behind a large ragged ulcer,
which generally involves only the
mucous membrane, but may extend
even through the muscularis and
rarely through the serosa, thus producing perforation.
Hemorrhage may also occur with the separation of the slough.

FIG. 178.

A typhoid ulcer of the
intestine (Green).

388 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

The resulting ulcers usually conform to the size and shape
of the patch involved (Figs. 178 and 179) ; especially in the

FIG. 179.

A typical ulcer of the intestine (diagrammatic), showing the undermined edges of
the ulcer and the slough still adherent : a, epithelial lining; b, submucous
tissue ; c, muscular coat ; d, peritoneum (Green).

lower part of the ileum, however, the ulcers are liable to
coalesce, and thus involve extensive areas of the mucous
membrane. The solitary follicles undergo necrosis in a similar
manner, resulting in the formation of rounded ulcers. By
the end of the third week this stage of ulceration is generally
complete, and during the fourth week cicatrization is in prog-
ress, finally leaving behind thin, transparent, flexible scars,
which often can be recognized years afterward ; the lymph-
atic elements are not replaced.

Microscopically the swelling of the patches and follicles is
found to be due mainly to an active proliferation of their
lymphoid cells; a few larger epithelioid cells are usually
present.

Coincident with these intestinal lesions of typhoid, the
mesenteric glands, in relation to the areas most affected,
become swollen from a similar inflammatory hyperplasia, and
to an extent in proportion to the severity of the intestinal
lesion.

Enlargement of the spleen is also almost constantly present —
produced by its congestion and an increase of its lymphoid
elements ; large epithelioid cells are often present, as in the
intestinal lesions and mesenteric glands, which are actively
phagocytic, frequently having encysted within them fragments
of red corpuscles.

The spleen, as well as the liver and kidneys, are often the
seat of necrotic foci. The typhoid, bacilli can usually be
demonstrated in large clumps, in properly stained sections of
the spleen (Figs. 180 and 181), though the whole organ may
possibly be cut up in a vain search for them. They are also
present in the intestinal lesions, mesenteric glands, liver and
kidneys, in the dejecta, and can sometimes be found in the

TYPHOID FEVER.

FIG. 180.

389

; ..^ ^ ^

Human spleen, tenth day of enteric fever (Charcot).
FjG. 181.

VX5N

Human liver, tenth day of enteric fever (Charcot).

blood. In the absence of a leukocytosis, the blood of typhoid
presents a marked clinical contrast to the blood in other acute
infectious diseases.

390 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

The lesions of other organs are in no way characteristic of
the disease. Parenchymatous or granular degenerations are
found in all toxaemias of sufficient degree and duration ; the
liver, kidneys, and heart-walls are so affected.

Inflammation of the pericardium, endocardium, or myo-
cardium is not uncommon.

A peculiar waxy or hyaline degeneration, which may occur
also in other infectious diseases, involves the voluntary muscles,
the fibres being converted into a homogeneous, colorless, shin-
ing mass resembling amyloid degeneration, but not giving its
characteristic reaction with iodine and sulphuric acid, and
affecting most frequently the abdominal muscles, adductors
of thighs, the pectorals, the diaphragm, and sometimes the
myocardium.

Bronchitis, lobar and lobular pneumonia are frequent com-
plications ; gangrene of the lungs a rare one. Occasionally
there is an inflammation of the parotid gland, which tends to
terminate in abscess-formation. A grave peritonitis is gener-
ally the result of perforation, though it may have its starting-
point in a deep ulcer which involves, but does not perforate
the serosa ; or it may be due to the inflammation involving
the mesenteric glands.

An obliterating endarteritis may occur, especially during
convalescence, leading to thrombosis and necrosis of the tissue
supplied. Thrombosis may also occur in the veins, especially
the femoral, rarely in the cerebral sinuses.

An orchitis occurring during convalescence, and frequently
terminating in suppuration, has been described.

Tuberculosis, though scarcely ever noted in the oesophagus
or stomach, very frequently affects the intestinal tract — in fact,
is one of the most common pathological conditions met in the
intestine. While not necessarily confined to the lymphadenoid
tissue, these structures are especially involved, the lesions
being most numerous in the lower part of the ileum and in
the colon. It may be primary — rarely in adults, though some-
what more frequently in infants ; generally it is secondary to
tuberculosis of the lungs, and the result of swallowing infected
sputum.

The tubercle appears beneath the mucous membrane

SYPHILITIC ULCERATION. 391

as a grayish nodule ; soon it becomes yellowish from rapidly
advancing caseation, and finally breaks down completely.

The resulting ulcer generally involves the muscularis ; its
floor is rough and nodular, from the presence of small tuber-
cles, which can be seen beneath the serosa externally (Fig.
182). The ulcers at first resemble somewhat those of

FIG. 182.

Tubercular ulcer of the intestine (Kaufmann). The cavity of the ulcer was formed
through disintegration and removal of the cheesy matter formed in the earlier
tubercles. Now the base of the ulcer is formed by necrosed and cheesy ma-
terial, beneath which eight or nine distinct tubercles are distinguishable, those
in the centre extending into the muscular coat of the intestine. The infection
has also extended into the lymphatics beneath the serous coat, where three
tubercles can be seen.

typhoid fever ; but soon, as the result of breaking down of
other newly-forming tubercles at their margins, the ulceration
extends beyond the limits of the lymphoid tissue, no longer
conforming to the size and shape of these structures. Fresh
tubercles being formed in this way along the line of the lym-
phatic vessels, which run toward the mesentery, the long axis
of the ulcer becomes transverse, a complete ring of mucous
membrane being destroyed, in some cases, in this manner —
annular ulcer. The border of the ulcer, like its base, is infil-
trated here and there with small tubercular nodules. On the
external serous surface radiating lines are noted, extending
from the base of the ulcer around the intestine toward the
mesentery, marking the tubercular infiltration of the subserous
lymphatics. Perforation is rare, owing to this infiltration and
thickening of the tissues. The corresponding mesenteric
glands are generally affected. If the ulcer heals, which is
infrequent, a puckered scar and possibly cicatricial deformities
remain.

Microscopically -, the characteristic feature is the presence of
small tubercles in the floor and walls of the ulcer.

Syphilitic ulceration of the solitary follicles and Fever's
patches of the small intestine sometimes occurs in infants.

392 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

In adults, though the small intestine and colon may rarely be
involved, the rectum is the part of the intestinal tract most
frequently affected.

TUMORS.

Carcinoma is the most important and most frequent tumor
affecting the intestinal tract, though not nearly as common as

FIG. 183.

Alv

Section showing degenerative changes in carcinoma of the rectum : Me, mucosa ;
Smc, submucosa ; M. int, inner muscular fibres (circular) ; M. ext, outer muscular
fibres (longitudinal); V, bloodvessels ; Ad, margin of growth, showing hyper-
trophied follicles and submucous tissue infiltrated with new adenoid tissue ;
X, mucus; Ca, ulcerated portion of the superficial surface of the growth ; XX,
remains of gland-follicles still recognizable ; Alv, glandular recesses dilated into
distinct alveoli; Col, large alveoli filled with mucoid or colloid material; Str.
stroma; Met, adenoid proliferation infiltrating deeper layers of bowel-wall
(Esmarch).

in the stomach. In the small intestine it is rare, the duode-
num near the opening of the bile-duct being the point at
which it usually is situated. More frequently it occurs in the

LIVER — ACUTE YELLOW ATROPHY. 393

rectum, the caecum, and flexures of the colon. It usually pre-
sents as a solitary, soft, often ulcerating, fungous mass, which
projects into the lumen of the intestine (Fig. 183).

Microscopically, the adeno-carcinoma or cylindrically-celled
cancer is the variety most frequently noted.

Connective-tissue tumors are not often found in the intestinal
tract.

THE LIVER.

PASSIVE HYPER^IMIA.

Passive hyperaemia is produced by some obstruction to the
circulation through the hepatic vein, as by a large pleuritic
effusion; intrathoracic tumors, cirrhosis of the lungs; and
especially valvular disease of the heart. At first the liver is
often considerably enlarged ; on section, it has a peculiar
mottled or nutmeg appearance, the darker congested areas
around the central hepatic vein of the lobule contrasting
markedly with the lighter periphery, which may be yellowish
or yellowish-white from advancing fatty degeneration. At a
later stage the liver is decreased in size, from atrophy of the
parenchyma-cells produced by the excessive pressure of the
blood ; and there may be very considerable hyperplasia of the
connective tissue, giving the organ a slightly roughened or
uneven surface.

Microscopically, the central hepatic vein and surrounding
capillaries are greatly dilated and engorged with blood. In
the centre of the lobule the rows of liver-cells between the
dilated capillaries are entirely atrophied. In the peripheral
zone of the lobule there is often an advanced fatty degenera-
tion.

ACUTE YELLOW ATROPHY.

Acute yellow atrophy of the liver occurs as an independent
specific disease ; or secondarily to phosphorus-poisoning,
typhoid fever, puerperal septicaemia, and other infectious
diseases. As an independent affection, however, it is ex-
ceedingly rare.

Anatomically, the characteristic feature of the disease is the

394 DISEASES OF THE GASTRO-TNTESTINAL TRACT.

rapid diminution of the liver to one-half, even one-quarter its
natural size, as the result of extensive degenerative changes
of the parenchyma. This reduction in size affects mainly its
vertical diameter, the organ being flattened out against the
spinal column to a few centimetres in thickness, and almost
concealed by the diaphragm and superimposed coils of intes-
tine. It is ochreous-yellow in color, soft and flabby, in
places almost pulpy ; or the yellow alternates with relatively
firmer red patches — so-called red atrophy — giving the surface
a mottled appearance, especially on section. The capsule is
wrinkled to such an extent that it can be picked up by the
fi ngers.

Microscopically, the outlines of the lobules are indistin-
guishable. The liver-cells are in various stages of degenera-
tion or necrosis ; in the yellow areas their outlines may be
preserved, but their protoplasm contains numerous fat-globules
and granules of yellow pigment ; or the cells may be entirely
replaced by a detritus of yellow pigment ; and irregular col-
lections of fat- globules, only the connective- tissue framework
of the liver remaining. In the red areas the cells are entirely
wanting, the tissue being colored by an infiltration with hema-
togenous pigments.

INFLAMMATIONS.

Acute purulent inflammation (Fig. 184) of the liver results
in the formation of one or more circumscribed collections of
pus. The avenues open to infection by the invasion of va-
rious micro-organisms are numerous : the hepatic artery,
portal vein, bile-duct, arid the patent umbilical vein in infants ;
or infection may extend from neighboring organs through the
lymphatics. The bacillus coli communis, staphylococci, and
streptococci are the organisms which have been most frequently
found associated with these purulent inflammations of the
liver; in cases following dysentery the amoeba coll is fre-
quently found in the pus.

The single large so-called tropical abscess is a very common
affection in the torrid zone, often as a sequela of dysentery.
It may be associated with the presence of tumors or parasites
in other cases. The abscess is generally situated in the right
lobe, and varies in size from a man's fist to that of a child's

LIVER— TROPICAL ABSCESS.

395

head ; an entire lobe or even the whole organ may be in-
volved. It may rupture into the pleural or peritoneal cavi-
ties, into the stomach, intestine, or externally through the

FIG. 184.

Abscess of liver in a case of pysemic infection through a wound in the appendix
vermiformis caused by lodgement of a pin (Loomis and Thompson).

abdominal wall. As to the mode of their formation, but little
is known ; undoubtedly they often result from the confluence
of smaller abscesses.

The walls of the abscess are ragged — shreds of necrotic liver-

396 DISEASES OF THE GASTRO-INTESTINAL TRACT.

tissue projecting into the cavity ; there is no trace of a mem-
brane. The contents of the cavity have an offensive, sickly
odor ; are thick and creamy like pus, or thin and reddish-
brown from the admixture of extravasated blood.

Microscopically, this fluid is found to contain pus-cells, frag-
ments of degenerated liver-cells, shreds of connective tissue,
and red blood-corpuscles. The abscess-wall shows but little,
if any, inflammatory infiltration.

Small metastatic abscesses, varying in size from a pin-head
to that of a walnut, are sometimes present to the number of
forty or fifty, scattered throughout the liver. They occur in
the course of pyaemia and septic inflammations of parts tribu-
tary to the portal vein.

Microscopically : In the early stage of their formation there
is noted an area of necrosis, the centre of which may have
become simply a granular detritus arising from the disinte-
gration of the liver-cells. Surrounding the necrotic area is a
zone of more or less marked inflammatory infiltration.

Chronic interstitial inflammation or cirrhosis of the liver is
also known as " gin-drinkers' " liver, for at least two-thirds
of the cases are due to chronic alcoholism. Certain acute in-
fectious diseases, chiefly cholera, typhoid, and intermittent
fever, are supposed by some to be important etiological fac-
tors. Among chronic infectious diseases, syphilis is an un-
doubted cause of cirrhosis. Gout and rheumatism seem to be
responsible for some cases. Experimentally, the condition has
been produced in lower animals by chronic poisoning with
phosphorus and cantharides. Though in most instances
hematogenous in its origin, in some it is biliary, due to an
obstruction of the bile-ducts.

In the early stages the liver may be considerably hyper-
trophied ; finally, however, in the great majority of cases it is
reduced in size even to one-third the normal. The longer the
duration of the disease the greater the atrophy, and the tougher
and more leathery the consistence of the organ. Its surface
is rendered irregular by numerous nodular projections vary-
ing in size from a millet-seed to that of a hazclnut. The
yellow color of these granulations suggested to Lacnnec the
term cirrhosis (from xifipoz, yellow). On section a grating
sound is emitted, and the almost cartilaginous consistence of

HYPERTROPHIC OR BILIARY CIRRHOSIS. 397

the organ may be noted ; a network of connective-tissue bands,
running in all directions — extensions from the thickened
fibrous capsule of Glisson — is seen, which divides the paren-
chyma into small islets corresponding in size to the surface-
granulations. The yellow bile-stained groups of lobules and
pink interlobular fibrous tissue gives the cut surface a mot-
tled and granular appearance.

Microscopically, the chief characteristic is the chronic diffuse
inflammatory hyperplasia of the interstitial connective tissue,
and resulting atrophy of the parenchyma of the liver, at least
a numerical atrophy, as the hepatic cells which remain in the
projecting granulations or nodules frequently undergo a com-
pensatory hypertrophy to twice their normal size. As long
as the hyperplasia is in excess of the atrophic changes the
organ is enlarged. As the newly formed connective tissue
becomes more sclerotic, compressing the cells of the lobules
and the vessels from which they obtain their nourishment,
the atrophy which is produced, both by direct pressure and
interference with the blood-supply, sooner or later results in
a reduction in the size of the organ. The yellow appearance
of the nodules is in part due to the obstruction, produced by
the hyperplastic connective tissue, to the discharge of bile
from the bile-capillaries into the interlobular ducts; and in
addition there is generally an excessive accumulation of fat
in the liver-cells, resulting not only from the lessened blood-
supply, but also probably from the fact that there are fewer
cells in which to store the fat normally present in the liver.

The pathological changes begin as a round-celled infiltra-
tion of the interlobular connective tissue. Through the fur-
ther development of these migrated and proliferating cells
dense fibrous tissue is formed, the cellular character of which
is finally almost entirely lost, so that it comes to resemble
cicatricial tissue (Fig. 185). The result of the obliteration of
the portal capillaries is engorgement of the portal circulation,
the most important aspect of which clinically is the enormous
serous transudation into the peritoneal cavity, which is called
ascites.

Hypertrophic or biliary cirrhosis differs from the ordinary
atrophic variety, in that the connective-tissue hyperplasia,
which is interlobular or monolobular, does not have the same

398 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

tendency toward sclerosis and contraction, and as a result the
atrophic changes in the parenchyma are not so marked. The
term biliary is suggested by the fact that it generally arises

Atrophic cirrhosis of liver, a, acini, in parts much diminished in size; b, inter-
acinous bands of connective tissue. X 250 (Schmaus).

in connection with inflammation or obstruction of the bile-
ducts.

The inflammatory hyperplasia begins around the inter-
lobular bile-ducts, instead of around the branches of the portal
vein. Experimentally, a monolobular cirrhosis can be pro-

LIVER— PRIMARY CARCINOMA. 399

duced by obstruction of the bile-ducts, though in man it is by
no means a constant accompaniment of such an obstruction.
In some cases formation of new bile-capillaries is observed.
The organ is enlarged, its surface finely granular, and on
section yellow to dark green bile-stained patches are noted.
Clinically, jaundice is nearly always present, due to the
obstruction of the bile-ducts by the newly forming connective
tissue; the portal vein is not obstructed as in the atrophic
variety, so that ascites is generally absent.

The specific granulomata : Syphilitic lesions of the liver
occur generally as a diffuse cirrhosis, resembling the ordinary
atrophic cirrhosis, except that the bands of newly formed
connective tissue are much heavier. Characteristic gummata
may be present also, or they may occur unassociated with
connective-tissue hyperplasia ; they appear as yellowish or
grayish, firm rounded masses, with necrotic, cheesy centres,
varying in size from a pea to that of a hen's egg.

Tubercular lesions of the liver are rarely primary. Diffuse
miliary tubercles frequently occur, however, in the course of
general miliary tuberculosis ; in some instances there are a
few large foci only. A diffuse interstitial connective-tissue
hyperplasia is sometimes associated with the miliary tubercles.

TUMORS.

Primary connective-tissue tumors do not often occur in the
liver ; angiomata more frequently than any other. Melanotic
sarcoma has been observed, the black nodules of the neoplasm
scattered through the organ, varying in size from a millet-
seed to that of a man's fist; much more frequently, how-
ever, the tumor is secondary to melanotic sarcoma of the eye.

Primary epithelial tumors of the liver are also rare.

Primary carcinoma is exceedingly infrequent as compared
with the secondary. It occurs either as a large mass, gener-
allv in the right lobe, with secondary nodules throughout the
organ ; or it may occur as a diffuse infiltration, which resem-
bles atrophic cirrhosis of the liver by reason of the nodular
appearance of the surface, and the anastomosing bands of
fibrous tissue noted on section. But in the islets between

400 DISEASES OF THE OASTRO-1NTESTINAL TRACT.

them, however, there is seen under the microscope the atypical
structure characteristic of the neoplasm, and not liver-tissue.
Secondary carcinoma of the liver is quite common, occurring
generally in the form of rounded and umbilicated, pinkish
nodules, varying in size from a pea to that of an apple, and
often so numerous as to produce an enormous enlargement
of the organ. The liver- cells surrounding such a nodule
are greatly flattened and atrophied. Microscopically, their
structure usually recalls that of the primary tumor.

Echinococcus cyst is the most important parasitic disease of
the liver, and is produced by the larvaB of the tsenia echino-
coccus. There may be one or more cysts, varying in size up
to that of a man's head. They consist of a connective-tissue
capsule, inside of which is the parasitic cyst-wall proper, from
which originate smaller vesicles — brood- capsules — and the
heads of the immature tapeworms. As long as the parasite is
alive the cyst contains a clear non-albuminous fluid, in which
are found scolices, the size of a millet- seed, and characteristic
booklets.

THE BILE-DUCTS AND GALL-BLADDER.

Inflammation of the bile-ducts is generally secondary to an
inflammation affecting the mucous membrane of the duodenum.
It may also be produced by the presence of a gall-stone or an
intestinal parasite which has crept into the common duct.
The result is an obstruction to the outflow of bile, and conse-
quent absorption of bile-pigment, giving rise to the condition
known as obstructive jaundice. (A non-obstructive jaundice
may arise from increased haemolysis in various severe infec-
tious diseases — as yellow fever.)

Inflammation of the gall-bladder is quite common, and has a
tendency to end in suppuration. It may result from extension
of an inflammation from the bile-ducts, or be due to the
presence of gall-stones or retained bile.

Stenosis of the bile-ducts may arise from the pressure ex-
ternally of an aneurism, a tumor, or an inflammatory proc-
ess around the duct. Congenital atresia sometimes occurs.

Primary carcinoma of the gall-bladder is occasionally met ;
the irritation produced by the presence of gall-stones is looked
upon as a possible cause.

THE PERITONEUM. 401

THE PANCREAS.

Atrophy of the pancreas is not infrequently found in connec-
tion with diabetes mellitus.

Inflammation of the pancreas is a rare condition. Citrhosis
is generally secondary to an inflammatory process in some
adjacent tissue ; occasionally it is seemingly due to alcohol
and syphilis.

Carcinoma is the most important tumor found in the pan-
creas. It is generally situated at the head of the gland, though
the whole organ may be in\7olved.

THE PERITONEUM.

Inflammation of the peritoneum, or peritonitis, but rarely
occurs as a primary affection, as compared to the frequency of
this condition in the other large serous sacs, the pleural and
pericardial ; nearly always it is secondary. It may be acute
or chronic ; circumscribed or diffuse. So-called idiopathic cases
occur at times in which there is no demonstrable cause. In a
great majority of instances bacteria play a most important
part in exciting the inflammatory process. They may gain
direct access to the peritoneum from the blood in septicaemia,
pyaemia, and other infectious diseases. Much more frequently,
however, there is a local septic inflammation of some organ
which the peritoneum covers — as of the uterus and its appen-
dages, and of the appendix vermiformis. The bacillus coli
communis has frequently been found in cases associated with
affections of the intestinal tract. Micro organisms met with
in other instances are the streptococcus and staphylococcus
pyogenes, diplococcus pneumonia?, and gonococcus.

When the infection takes place gradually and the organisms
are in small numbers, the inflammatory process may be local-
ized— as in connection with appendicitis and affections of the
pelvic viscera. The entire peritoneum may subsequently
become involved, as the result of extension of the inflamma-
tion ; in other cases it is immediately involved by the intro-
duction of a large amount of infective material — as
perforation of the stomach, or intestine,
abscess into the peritoneal cavity.

26— Hist.

\\\\\i i//"///

402 DISEASES OF THE G ASTRO-INTESTINAL TRACT.

Chronic peritonitis is characterized by thickening of the
peritoneum, and the formation of adhesions between opposed
inflamed serous surfaces, as in pleurisy.

Tuberculosis, primarily affecting the peritoneum, is rare.
The most frequent sources of infection secondarily are tuber-
cular affections of the mesenteric and retroperitoneal lymph-
atic glands, of the vertebrae, and of the pelvic organs in the
female ; miliary tubercles may occur in general miliary tuber-
culosis.

CHAPTER VII.
DISEASES OF THE URINARY ORGANS.

THE KIDNEYS.
PASSIVE HYPER.EMIA.

Passive hyperaemia occurs in conjunction with valvular disease
of the heart, and diseases of the lungs, which seriously impede
the circulation — as fibroid phthisis and severe emphysema.

The kidneys are generally enlarged in the earlier stages,
are firm and elastic ; the capsule, which is not adherent, may
readily be removed, exposing a smooth surface. On section,
the cortex is found to be congested and swollen ; the Mal-
pighian bodies may be enlarged and stand out prominently ;
the pyramids are deeply congested, and have a striated ap-
pearance, produced by dilatation of their bloodvessels.

At a later stage, there may be a very considerable hyper-
plasia of interstitial connective tissue, and the organ conse-
quently more or less decreased in size and dense — cyanotic
induration.

Microscopically, the prominent features are the dilatation
and overfilling of the bloodvessels ; atrophy of the epithelium
of the tubules, and a marked increase in the amount of inter-
stitial connective tissue. Quite often there are small extrava-
sations of blood within the capsule of the Malpighian bodies.

BRIGHT'S DISEASE

To bilateral inflammations of the kidneys, in which the
irritant has gained access through the blood, the generic term
Bright's disease is applied, after the clinician who first ex-
plored this important field of pathology, and called attention
to the relation of certain structural changes in these organs —
the inflammatory nature of which was later recognized — to
albuminuria and general dropsy.

403

404 DISEASES OF THE URINARY ORGANS.

There is nothing distinctive of inflammatory processes in
the kidneys. As in other organs, though inflammation affect-
ing either the parenchyma or interstitial connective tissue
alone does not occur, the changes may be so much more con-
spicuous in one or the other as to suggest the term parenchy-
matous or interstitial inflammation.

In acute inflammation produced by intense irritants, the
glomeruli and epithelium of the secreting tubules are mainly
affected ; while in other instances in which the irritant is less
intense and acts over a prolonged period, the inflammatory
changes predominate in the interstitial connective tissue.

Casts.

Casts of the uriniferous tubules have been objects of very
considerable interest in connection with these pathological

FIG. 186.

a, epithelial casts ; 6, opaque granular casts (from a case of acute Bright's disease ;

Roberts).

changes since 1842, when attention was first directed to them
by Henle. They are found in the urine, and in the urinif-

CASTS.

405

erous tubules at the site of their formation, in nearly all
inflammations of the kidneys, and are but rarely present in
normal urine.

The method of their formation is not perfectly understood
— some probably by a species of secretion from the tubular
epithelium, and others by coagulation of serous exudations
into the tubules.

In size they vary according to the part of the kidney in
which they are formed, measuring from 0.01 to 0.05 milli-

FIG. 187.

Granular casts (Musser).

metre in diameter, and one-tenth to a millimetre and more
in length. Several varieties are distinguished.

Hyaline casts are homogeneous, transparent, and colorless.
They are found in the urine from simply congested kidneys,
and in transient albuminuria ; often, moreover, in chronic
parenchymatous and interstitial nephritis.

Granular casts are composed of a granular material re-
sulting from the breaking down of the epithelial cells of the
tubules. They are found especially in the urine from chronic-
ally inflamed kidneys.

406 DISEASES OF THE URINARY ORGANS.

FIG. 188.

Fatty casts from a case of chronic parenchymatous nephritis (Musser).
FIG. 189.

Hyaline casts from a case of acute nephritis: 1, plain hyaline cast- 2 eranular
deposits (hyaline casts;; 3, cellular deposit (blood and epithelium) (MufsS

Cellular casts occur when epithelial cells, or red and white
blood-corpuscles cling to either of the above varieties.

ACUTE PARENCHYMA TO US NEPHRITIS.

407

Waxy casts have a peculiar glistening appearance, which
distinguishes them from the hyaline variety. The last two
varieties occur in both acute and
chronic nephritis (Figs. 186-190). FIG. 190.

ACUTE PARENCHYMATOUS
NEPHRITIS.

Acute parenchymatous nephritis
may be a primary affection, occur-
ring often without discoverable cause ;
or secondary, as a rather frequent
complication of scarlet fever, diph-
theria, and other acute infectious
diseases, and of pregnancy.

Clinically, the condition is charac-
terized by acute onset, scanty, albu-
minous, and often bloody urine,
dropsy, and uremia ; the most
prominent features are headache,
coma, and possibly convulsions, due
to retention in the blood of noxious
substances, normally eliminated by
the kidneys.

Anatomically, the appearance of
the kidney varies considerably, ac-
cording to the duration and intensity
of the affection.

Macroscopically, in some instances of acute parenchymatous
nephritis, especially where the inflammatory process is limited
to the glvmeruli — glomerulo-nephritis — further than a slight
hyperaemia and swelling of the cortex, there may be but
little evidence of the changes which have taken place. Gen-
erally, however, the organ is enlarged, often to twice its natural
size, flabby and friable ; its capsule is tense, gaping widely on
being incised, and is easily detached, exposing a perfectly
smooth surface. In the early stages the organ may be deeply
congested ; but later it is often pale— in proportion to the
swelling and degenerative changes in the tubular epithelium,
and the inflammatory cellular and serous exudations which
express the blood from the interlobular vessels.

Different forms of waxy casts
(v. Jaksch). •

408

DISEASES OF THE URINARY ORGANS.

On section, the swollen and rounded appearance of the
kidney is seen to be due mainly to a marked increase in the
thickness of the cortex. The cortex may be intensely hyper-

FIG. 191.

Parenchymatous nephritis, a, cross-section of a convoluted tubule of the kidney,
the lining epithelium of which is the seat of albuminoid degeneration. The
cells are swollen and their bodies filled with abnormally coarse granules. The
cells to the left are so far disintegrated that the nuclei have lost most of their
chromatin. Such cells cannot recover. The cells to the right are less pro-
foundly altered and their nuclei retain sufficient chromatin to stain slightly.
These cells might, perhaps, recover. Other convoluted tubules similarly
affected are represented in oblique section, b, tubule with low, unaffected
epithelium, the nuclei of which stain deeply ; c, round-cell infiltration of the
interstitial tissue in the neighborhood of a Malpighian body, the edge of which
is just above the line c. Section stained with hsematoxylin and eosin.

semic, with here and there small punctiform hemorrhages, the
distended glomeruli standing out prominently as dark red
points ; or mottled in appearance by yellow patches of fatty

ACUTE PARENCEYMATOUS NEPHRITIS. 409

degeneration ; or of a uniform gray color in advanced stages,
when the leukocytic infiltration has been excessive — contrast-
ing strongly with the pyramidal portion, which is generally
deeply congested.

Microscopically, also, the appearances presented in acute
parenchymatous nephritis differ greatly both in the extent
and character of the lesion. In some instances the changes
are almost entirely confined to the tubular epithelium ;
resembling rather an acute degeneration than an inflammation.
At other times there is a diffuse inflammatory infiltration, in
addition to more or less marked changes in the tubular epi-
thelium (Fig. 191) ; in still other cases, to which the term
glomerulo-nephritis has been applied, the inflammatory changes
begin in and are most marked around the glomeruli, though
sooner or later becoming more general.

Just what the essential differences are, in the character of
the exciting cause, which are factors in producing the varied
lesions noted above, is not kno\vn ; though it might be argued
that, when the poisonous substance or irritant is being elimi-
nated by the epithelial cells of the secreting tubules, the
changes may be most marked there ; but if of such a character
as to be more readily eliminated with the watery constituents
of the blood by wray of the glomeruli, the primary inflamma-
tory changes may be excited at that point.

The changes in the uriniferous tubules, most marked in the
convoluted portions in the cortex, consist of a granular and
fatty degeneration of the epithelial cells, some of which
become desquamated and distend the tubules ; at the same time
the epithelial cells in places may show proliferative changes.
The epithelium of the glomeruli may undergo similar degen-
erative and proliferative changes, and the whole tuft become
enlarged from engorgement of its bloodvessels. Migrated
leukocytes, and small masses of extravasated red blood -cor-
puscles, are often seen in and around the tubules and glomeruli.
To this class of cases, in which the parenchymatous changes
are the most marked feature, the term catarrhal or desqua-
mative nephritis has been applied.

As has been noted, in some cases, especially those occurring
in the course of scarlet fever, the inflammatory changes begin
in the Malpighian bodies — glomerulo-nephritis. The glomeruli

410 DISEASES OF THE URINARY ORGANS.

are swollen and infiltrated with leukocytes, and their capillary
bloodvessels engorged. Bowman's capsule is thickened ; its
cells swollen, degenerated, and desquamated. The interlobular
arteries are more prominent than normal, and are surrounded by
migrated leukocytes. The leukocytic migration may be slight
or excessive — occurring in foci or as a diffuse infiltration of
the cortex. In some cases, even at an early date, there is noted
a beginning organization of these migrated and proliferating
cells into more or less highly developed connective tissue.

CHRONIC NEPHRITIS.

Chronic nephritis may follow an acute attack, but in the
great majority of cases it arises insidiously as an independent
affection. Clinically and anatomically, two varieties of
chronic nephritis are recognized : one in which the changes
are most marked in the parenchyma of the organ, and asso-
ciated clinically with general dropsy and the passage of small
quantities of urine of low specific gravity, loaded with albu-
min and casts — chronic parenchymatous nephritis; and the
other, in which the increase in connective tissue is the most
marked feature anatomically, and characterized clinically by
the absence of dropsy, and passage of large amounts of pale
urine containing comparatively small quantities of albumin
and but few casts — chronic interstitial nephritis. These two
varieties may be different stages of one affection, but, on the
contrary, many cases of chronic parenchymatous nephritis
never go on to cirrhosis ; and often, in other instances, the
connective-tissue hyperplasia is the most prominent feature
from the earliest stages of the inflammatory process.

In chronic parenchymatous nephritis the kidney is generally
enlarged, usually to a greater extent even than in acute nephri-
tis. The capsule is readily removed, exposing a smooth sur-
face, except, at a somewhat later stage, for slight irregularities
here and there, where bits of the parenchyma have become ad-
herent to the capsule and caused small lacerations on tearing it
away. The surface is mottled and anaemic, its pale appear-
ance earning for it the term large white kidney, though this
term is applied to amyloid degeneration, and other conditions
not included under the head of chronic parenchymatous
nephritis. In consistency the organ is doughy.

CHRONIC INTERSTITIAL NEPHRITIS. 411

On section, the cortex is found to be two or three times
its normal thickness, its mottled appearance being due to
patches of fatty degeneration in the tubular epithelium.

The microscopical lesions are the same as in acute parenchy-
matous nephritis, only more marked. The most prominent
feature is the degenerative changes in the epithelium of the
convoluted tubules ; the epithelial cells are swollen, granular,
and many are in an advanced stage of fatty degeneration,
finally breaking down completely, and filling the lumen of the
tubule with a granular and fatty debris, the lining epithelium
being entirely destroyed. Within the tubules may be also
hyaline, granular, and fatty casts. There is generally some
increase in the intertubular connective tissue. The changes
in the glomeruli are equally marked, increased thickness of
Bowman's capsule and of the connective tissue between the
capillaries tending to convert them into atrophied fibrous
bodies.

In chronic interstitial nephritis the kidney is usually greatly
reduced in size — to less than two ounces in extreme cases — and
is remarkably tough in consistency ; its surface is of a reddish-
gray tint, and uneven from the presence of small nodules or
granulations, fairly regular in size — about that of a millet-
seed. The capsule is thickened, opaque, and firmly adherent.

On section , the most noticeable feature is the marked atrophy
of the cortex, appearing as a narrow rim but a few millimetres
in thickness. The pyramids are also reduced in size, the
atrophy of the intervening glandular tissue giving them the
appearance of being closely packed together.

Microscopically, the prominent features are the atrophy of
the glomeruli and uriniferous tubules, the tubular epithelium
having undergone granular and fatty degeneration ; and great
increase in the connective-tissue stroma. The majority of
glomeruli have become dense and fibrous nodules, but one-
half their normal size. Here and there may be well-preserved
tubules and glomeruli. Occasionally tubules are met which
seem to have undergone a sort of complementary dilatation,
as the result of obliteration of tubules in other areas, becom-
ing so exaggerated in some instances as to form cysts, large
enough to be seen with the naked eye. Sometimes these
cysts occur in rows, suggesting their origin from a single

412 DISEASES OF THE URINARY ORGANS.

tubule ; they may also result from the dilatation of Bowman's
capsules, and are often filled with a colloid material. Hya-
line and granular casts may be found within the tubules. At
an early stage of the inflammatory process the interstitial
tissue may be quite cellular, but the longer the duration of the
affection the more fibrous and the greater the increase in the
stroma ; from its contraction results the granular appearance
of the surface. The walls of the bloodvessels are almost
invariably thickened by an obliterating endarteritis

Associated with these lesions in chronic interstitial nephritis
are nearly always a general arterio-sclerosis and a hypertro-
phied heart.

DEGENERATIONS.

Parenchymatous degeneration, or cloudy swelling of the kid-
neys, occurs in the course of diphtheria, scarlet fever, cholera,
and other infectious diseases ; and in poisoning from phospho-
rus, arsenic, and mercury. There is no sharp line of demarca-
tion between this condition and acute parenchymatous nephri-
tis, in which it is liable to terminate, the changes varying with
the virulence of the poison. The kidney is enlarged, rounded,
and soft in consistency. On section, the cortex is thicker than
normal, and pale or yellowish in appearance.

Microscopically, the principal changes are noted in the
tubules of the cortex. The tubular epithelium is granular
and swollen ; the lumen of the tubule almost entirely oblit-
erated, often appearing as little more than a stellate fissure.
The cell outline is indistinct and its nucleus obscured.

Fatty degeneration very frequently follows cloudy swelling ;
it often occurs also in the course of long-continued wasting
diseases, as cancer, tuberculosis, diabetes, and pernicious
anemia. The kidney is pale and extremely flabby, and
often smaller than normal ; on section the cortex is found to
be of normal thickness, and of a diffuse yellowish or mottled,
and greasy appearance.

Microscopically, the convoluted tubules are especially af-
fected ; the cells are swollen, and near their bases are droplets
of fat of various size.

Amyloid degeneration of the kidneys occurs in tuberculosis.

KIDNEYS—THE SPECIFIC GRANULOMATA. 413

syphilis and other cachexias ; and is associated with similar
changes in the liver, spleen, and abdominal lymphatic glands.
It is generally accompanied by albumin uria, and in advanced
stages by general dropsy.

At an early stage the kidney may appear perfectly normal
to the naked eye. Later, however, it is enlarged, often to
twice its normal size, pale, anaemic, and very firm and tough.
The capsule can be readily removed, exposing a surface
smooth, polished, and glistening. On section, the cortex is
thickened and has a peculiar transparent, homogeneous, bacony
appearance.

Microscopically, the changes are found to begin in the walls
of the bloodvessels as in other organs, and hence are most
readily recognized at an early stage in the Malpighian bodies,
which appear, unstained, as prominent, transparent or trans-
lucent, polished clumps. The rose color imparted to the
amyloid material by the use of methyl violet as a stain, gives
the capillaries of the tufts the appearance of being injected.
Later the changes are noted in the afferent and efferent vessels
of the tufts, and arterise recta?. Not infrequently the base-
ment-membrane of the uriniferous tubules may be similarly
affected — the lining epithelium being in various stages of
granular and fatty degeneration. This degenerative change
is often associated with parenchymatous and interstitial ne-
phritis.

THE SPECIFIC GRANULOMATA.

Syphilis in its early stages may give rise to a nephritis
similar to that produced by other infectious diseases. In its
later stages it is a very frequent cause of amyloid degenera-
tion, and may also produce a chronic interstitial nephritis.
Syphilitic gummata of the kidneys are very rare.

Tuberculosis occurs as a part of an acute miliary or chronic
general tuberculosis, though cases are seen in which the disease
starts primarily in the kidneys ; infection may take place
also along the ureters, secondarily to tuberculosis of the tes-
ticles, seminal vesicles, and bladder. The disease is generally
more marked in one kidney than in the other, or may be
entirely confined to one. In primary tuberculosis of the
kidneys, at an early stage, the tubercular foci — small yellow

414 DISEASES OF THE URINARY ORGANS.

caseous nodules — may be confined to the bases of the pyra-
mids. Discharge of the necrotic tissue often occurs into the
pelvis of- the kidney, which is generally also involved — a
tubercular pyelo-nephritis. At a later stage the whole organ
is sometimes converted into a large sac, with caseous and ul-
cerating walls.

TUMORS.

Fibromata are not infrequently found in the kidney in the
form of small, firm, white nodules about the size of a millet-
seed, though sometimes much larger.

Lipomata are rare, but the fatty external capsules of the
kidney may be so greatly increased in thickness as to form
practically a fatty tumor (Fig. 1 1 9).

Simple adenoma has been met with in the kidney, but is
very rare. Small tumors sometimes occur, which are formed
of a displaced remnant of the suprarenal capsule, and histologi-
cally resemble that gland.

Leiomyomata occasionally occur in the kidney, and are
generally situated near the apices of the papillae. A rare
tumor, which is usually congenital, is the rhabdomyosarcoma,
histologically found to be composed of round and spindle-
cells mixed with striated muscle-cells.

Primary sarcoma of the kidney is more frequent than
primary carcinoma. Microscopically, it varies considerably
in size and appearance. Microscopically, the varieties most
frequently met are the round and spindle-celled, the myxo-
sarcoma, and myosarcoma.

Primary carcinoma of the kidney is rare. It generally be-
gins in the cortex as an adeno-carcinoma.

Cysts occur frequently in the course of chronic interstitial
nephritis, and even in the otherwise normal kidney, as the
result of obliteration and dilatation of the uriniferous tubules
and Bowman's capsule, and may attain sometimes a very con-
siderable size. They may be so numerous as to cause sur-
prise that the kidney should have been able to perform its
functions at all. Congenitally, both kidneys may be trans-
formed into masses of innumerable cysts of varying size,
these organs being so greatly enlarged in some cases as even

PELVIS OF THE KIDNEY. 415

to interfere with parturition. Dermoid cysts are also found ;
echinococcic cysts are of occasional occurrence.

PELVIS OF THE KIDNEY.

In inflammation of the pelvis of the kidney — pyelitis — and
the associated lesions in the kidney itself, infection takes place
most frequently by way of the ureter, in connection with
urethral stricture, enlarged prostate, vesical calculus, and
cystitis. Though pyelitis may occasionally occur in the course
of infectious diseases and in non-infectious cases, for example,
as the result of the mechanical irritation produced by the pres-
ence of calculi, calculous pyelitis ; yet in the majority of
cases it is a septic or suppurative inflammation produced by
micro-organisms. Sooner or later there generally follows a
suppurative inflammation of the kidney itself — pyelo-nephritis.

FIG. 192.

Hydronephrosis with granular atrophy of the kidney. The other kidney showed a
marked compensatory hypertrophy (Virchow).

In pyelo-nephritis the kidney is swollen, soft, and friable,
its surface dotted with small yellow elevations which contain
pus. In size and number these abscesses may vary greatly.
They may be few and confined mainly to the cortex, or the
whole kidney may be fairly riddled with larger confluent ab-
scesses, communicating with the pelvis of the kidney, the
whole organ in some instances being converted into a large
pus-sac— pyo-nephrosi*. When obstruction of the ureter causes

416 DISEASES OF THE URINARY ORGANS.

dilatation of the pelvis and calices of the kidney, hydroneph-
rosis is the descriptive term (Fig. 192).

Calculi not infrequently occur in the pelvis of the kidney,
sometimes attaining quite large dimensions; the term renal
gravel is applied to the smallest gritty particles. During
their formation the calculi often become more or less accu-
rately moulded to the shape of the pelvis and the calices.
They may be composed of uric acid, oxalate of lime, and
phosphates, and rarely of cystin and xanthin. The results
of their presence may be very serious. The smallest particles
may pass through the ureter from time to time and give rise
to attacks of excruciating pain— renal colic; larger ones, by
obstructing the ureter and the outflow of urine, may cause
hydronephrosis. The continued irritation produced by a
large calculus results generally in a pyelitis, and in some cases
seems to be the exciting cause of cancer.

URINARY BLADDER.

Fissure of the bladder — a congenital malformation — is
rather common, occurring as the result of a failure of the
visceral arches to coalesce in front. The absence of the
anterior wall of the abdomen and bladder exposes to view,
protruding and filling the cleft, the inflamed mucous mem-
brane of the posterior wall of the bladder which has been
pushed forward by the abdominal viscera — exstrophy. The
extent of such a fissure varies greatly. It may involve the
pubic bones, and in the female, the vagina, clitoris, and urethra;
or the bladder may be perfectly formed and the cleft confined,
in the male, to the urethra, constituting an epispadms.

Hypertrophy of the muscle- walls of the bladder results
from some obstruction either of the neck of the bladder or of
the urethra — as by enlargement of the middle lobe of the
prostate or a urethral stricture.

The mucous membrane of the bladder is raised into trabec-
ulse by the bundles of hypertrophied, interlacing muscle-
fibres, giving rise to an appearance somewhat similar to the
inner surface of the ventricle of the heart.

Inflammation of the bladder — cystitis — may be acute or

URINARY BLADDER— TUMORS. 417

chronic, and varies considerably in its severity. The inflam-
matory process may extend from the urethra in gonorrhoea ; or
result from the presence of vesical calculus ; or occur in the
course of acute infectious diseases. The introduction of
septic matter during catheterization is of common occurrence ;
and the decomposition of urine consequent upon the retention
of urine in urethral stricture or hypertrophied prostate is also
a frequent cause.

The mucous membrane in acute cases may be greatly swollen,
and congested, and present numerous punctate hemorrhages
and, at times, superficial sloughs ; its surface is covered with
a muco-purulent exudate, and in some cases a pseudo-mem-
brane.

In chronic cases the mucous membrane is greatly thickened,
and is often the seat of extensive ulceration ; if there be some
obstruction to the outflow of urine, the hypertrophied trabec-
ulae of muscle-fibres may give the surface a ribbed appear-
ance.

In other cases, as the result of the organization and subse-
quent contraction of the inflammatory infiltration of its walls,
the bladder is often much diminished in size. Incrustations
of phosphates deposited from the alkaline urine may cover
the surface of the mucous membrane.

The thick, tenacious, gelatinous material often present in
the urine, in addition to large quantities of migrated leuko-
cytes, is not due to the presence of mucin, but is the result of
the action of the alkaline urinary salts on the purulent exu-
date. Infection is liable to extend along the ureters to the
kidneys.

Tuberculosis of the bladder may occur in phthisis, but is
much more frequently secondary to tuberculosis of the kidney,
uterus, prostate, epididymis, or seminal vesicles.

The lesion generally presents as a single large, or numerous
small ulcers, most abundant at the base of the bladder and
around the orifices of the ureters.

Tumors : Papillomata, varing in size from a pea to that of
a pigeon's egg, and often having a cauliflower-like appear-
ance, are of rather frequent occurrence. They are quite
vascular and bleed readily. Carcinoma is nearly always

27— Hist.

418 DISEASES OF THE URINARY ORGANS.

secondary ; the bladder is generally involved as the result
of the extension of the new growth from the uterus, vagina,
or rectum, or rarely by metastasis.

Calculi are frequently found in the bladder, varying greatly
in size and number. In some cases there is a single calculus
four or five inches in diameter ; in others, small gravel-like
particles.

The appearance of the larger stones varies according to
their composition. The uric-acid calculus is generally round
and hard, its surface smooth, and from a yellow to a red
color. Mixed or triple-phosphate calculi are also frequent.
They are white, soft, and friable, with roughened surfaces; or
occur as incrustations on the mucous surface of the bladder-
walls. Caldum-oxalate or mulberry calculi are brownish in
color, hard, and rounded, with irregular nodular surfaces.

THE URETHRA.

Inflammation of the urethra, which is in most instances due
to the gonococcus of Neisser, is a frequent and especially
serious disease, in its consequences, in the male. In the great
majority of cases the inflammatory process involves the entire
extent of the urethra, though it may be confined to that por-
tion anterior to the cut-off-muscle — anterior urethritis. The
gonococci rapidly penetrate between the epithelial cells beyond
the reach of antiseptics and astringents.

The mucous membrane is intensely congested and swollen,
and from it comes a thick, purulent exudate.

If the posterior urethra is involved, the gonococci are very
apt to invade the vas deferens, and excite an acute inflamma-
tion of the epididymis ; the prostate gland may be likewise
involved ; the bladder, however, is but rarely affected.

The inguinal lymphatic glands are frequently enlarged, the
inflammatory process sometimes terminating in suppuration.

Rarer complications of gonorrhoeal urethritis are arthritis
and inflammations of the pericardium and endocardium, and
even at times of the pleura and the spinal meninges.

Chronic urethritis not infrequently follows the acute. Gono-
cocci have been found as long as six years after an original

URETHRA— TUMORS. 419

infection in the purulent discharge from the urethra. Even
after the disappearance of these organisms, lesions — post-
gonococci — remain, which may give rise to serious conse-
quences. Chronic posterior urethritis is often responsible for
functional derangements of the nervous system — sexual neuras-
thenia. In this chronic stage the inflammation is no longer
diffuse, but circumscribed. The lesions consist of localized
areas of submucous infiltration and erosions, or even definite
ulcerations of the mucous membrane ; at times some patches
of granulation-tissue are noted.

Strictures often result at the site of these lesions from the
formation of cicatricial tissue. As they gradually encroach
upon the lumen of the canal and impede the outflow of urine,
the bladder-walls become hypertrophied ; but later this organ
is dilated, as likewise may be the ureters and pelvis of the
kidneys.

Tumors : Carcinoma of the urethra may result from exten-
sion of the new growth from adjacent organs, as the vulva,
vagina, and glans penis ; it is rarely primary, taking its origin
from Cowper's gland.

Sarcoma of the urethra does occur, but is very rare.

CHAPTER VIII.

DISEASES OF THE NERVOUS SYSTEM.
THE MENINGES.

Inflammation may involve both the cerebral and spinal
meninges, or either separately. The dura alone may be affected
— pachymeningitis ; the pia and arachnoid are usually affected
together — leptomeningitis, or simply meningitis.

In the cord, however, all three membranes are commonly
involved at the same time, together with the periphery of the
white matter of the cord itself, with which the meninges are
intimately connected.

Pachymeningitis : In the brain inflammation of the outer
layer of the dura — pachymeningitis externa — is generally
secondary to disease or injury of the bones of the skull, of
which it forms the periosteum. The inflammatory process is
usually suppurative and confined to limited areas, though it
may extend to the other membranes and the brain.

A suppurative pachymeningitis interna is generally asso-
ciated with a leptomeningitis or a pachymeningitis externa.

In chronic pachymeningitis there is a diffuse or circum-
scribed thickening of the membrane, which is abnormally
adherent to the cranium and to the arachnoid, and not infre-
quently an ossification of the outer layers of the membrane
takes place.

Hemorrhagic pachymeningitis, or hsematoma of the dura,
occurs especially in chronic alcoholics and the insane. The
condition is looked upon as a hemorrhagic inflammation of
the dura. There first forms a highly vascular subdural
pseudo-membrane, extending over the greater part of one or
both hemispheres, the hsematoma resulting secondarily from
rupture of its vessels. This pseudo-membrane presents the
appearance, microscopically, of granulation-tissue, and contains
many thin-walled bloodvessels.

420

LEPTOMEN1NGIT1S.

421

Leptomeningitis : In leptomeningitis the inflammatory proc-
ess nearly always involves the arachnoid and pia of both brain
and cord*. The condition may occur as an epidemic cerebro-
spinal meningitis; or in the course of smallpox, scarlet fever,

FIG. 193.

Hydrocephalus interims ; dilated ventricles (U. S. A. Museum, No. 8233).

pneumonia, septicaemia, and other infectious diseases. The
pneumococcus is the organism most frequently found asso-
ciated with the disease, having been met with in 60 per cent,
of all cases.

422

DISEASES OF THE NERVOUS SYSTEM.

In some cases the macroscopieal changes are not marked,
consisting simply of congestion, loss of normal lustre, and
slight oedema. In more severe cases the exudate, which may
be serous, sero-purulent, or purulent, becomes more marked,
and even distends the subarachnoidal space, the cerebral con-
volutions being flattened and the brain compressed to such
an extent as to give rise to coma. The ventricles may be like-
wise distended (Fig. 193). In some cases the exudate pre-

FIG. 194.

Fibrinous leptomeningitis. a, cerebral cortex ; 6, serum, with detritus, separating
the brain from the pia mater ; c, bloodvessel of the pia mater, the walls of whicn
are infiltrated with emigrating leukocytes ; d, fibrinous exudate ; e, smaller ves-
sel of the pia (Dunham).

sents as an extensive, thick, opaque, fibrinous deposit on the
under surface of the arachnoid. In other instances a green-
ish-yellow, purulent exudate may cover the surface of the
brain to such an extent as to conceal almost entirely the con-
volutions of the cortex (Figs. 194 and 195). The inflamma-

TUBERCULAR MENINGITIS.

423

tory process may extend to the substance of the brain, vary-
ing from slight oedema of the cortex to abscess-formation.

Tubercular inflammation of the meninges is more common
in children than in adults, and is usually part of a general
miliary tuberculosis or secondary to tuberculosis of other

FIG. 195.

- a

6 —

Serous leptomeningitis. a, cedematous fibrous tissue of the pia mater, the fibrous
elements of the tissue being separated by the serous exudate ; 6, group of leuko-
cytes, probably held together in part by fibrin ; c, granular fibrin and detritus : 6
and c and other similar masses, lie in the serum, which occupies the whole
field between the visible elements (Dunham).

regions of the body, most commonly the lungs. The miliary
tubercles are most numerous in the pia at the base of the
brain. The meninges are congested, and may be the seat of
exudations similar to those occurring in simple meningitis.
The ventricles of the brain are distended with a serous exu-
date and their walls studded with miliary tubercles. The

424 DISEASES OF THE NERVOUS SYSTEM.

cortex of the brain is congested and the convolutions flattened
by pressure from within.

At times large caseous nodules are found in the pia mater
and brain-tissue.

Syphilitic inflammation of the meninges is generally circum-
scribed. The gummata which form involve the pia and
the cerebral cortex, or they may extend outward and involve
the dura.

Tumors : Endothelioma is probably the tumor most fre-
quently met in the meninges. Lipomata, fibromata, and
myxomata are of rare occurrence.

THE BRAIN.

THROMBOSIS AND EMBOLISM.

The results of thrombosis and embolism in the brain may
be most serious, producing death, or more or less extensive
paralyses.

Emboli are brought most frequently from fibrinous vegeta-
tion on the cardiac valves, or from cardiac or aneurysmal
thrombi. They generally lodge in the left middle cerebral
artery.

Thrombosis is most frequent in the basilar artery, but may
occur anywhere, as the result of the presence of an embolus,
or some local inflammatory or degenerative alteration of the
vessel-wall at the site of its formation.

In either case the result of this obstruction of the blood-
supply is a rapid necrotic softening of the area affected —
encephalomalacia. The nerve-cells degenerate and lose their
axis-cylinder processes; the myelin-sheaths of the nerve-
fibres undergo fatty degeneration ; and later the neuroglia-
fibres a similar change. A more or less pigmented scar is
finally formed, composed mainly of neuroglia-tissue. In the
case of an infectious embolus, an abscess may form. These
areas of softening are usually red from the extravasation of
blood, as in infarcts in other organs ; at a later stage when
most of the pigment has been absorbed, or when little or no
blood has been extravasated, they are yellow or white.

CEREBRAL HEMORRHAGE. 425

ANEMIA.

Anaemia of the brain may depend on general anaemia, or in
acute cases be due to severe hemorrhage. The condition is
supposed to occur during sleep, in fainting spells and hysteri-
cal crises.

The gray and white matter on section appear much whiter
than normal, and the small puncta vasculosa are almost en-
tirely absent. A local anaemia may result from partial
obstruction of the blood-supply by a thrombus or embolus,
or the external pressure of a tumor.

HYPEKffiMIA.

An acute hyperaemia of the brain may be produced by ex-
cessive activity of the heart's action, and accompanies exces-
sive brain-work, sunstroke, acute delirium, and some infectious
diseases, as cholera and hydrophobia.

A passive hyperaemia may result from valvular disease of
the heart and from interference with the return circulation
through the jugular veins by pressure of a tumor, or by dis-
ease of the lungs — as extensive pneumonias and large pleuritic
effusions. The brain is enlarged, the bloodvessels of the pia
mater injected ; the gray matter may have a diffuse rosy tint,
and on section the puncta vasculosa are more conspicuous
than normal. In passive hyperaemia, however, the gray
matter has a slaty color and the sinuses and cortical veins are
widely distended. (Edema of the brain may result if the
condition is long continued.

CEREBRAL HEMORRHAGE.

The clinical term apoplexy is still used synonymously with
cerebral hemorrhage, of which it is the most striking symptom.

The most important factors in the production of cerebral
hemorrhage are increased blood-pressure and the degenerative
changes occurring in the bloodvessel-walls with advancing
years, and in the course of various diseases, notably syphilis.
The resulting clots vary greatly in size ; they may be as small
as a pea, or almost entirely occupy one hemisphere. Usually
there is but one clot. They occur most frequently in the

426 DISEASF:S OF THE NERVOUS SYSTEM.

corpora striata and optic thalami, and the brain-tissue imme-
diately surrounding.

If there is not a fatal termination of the hemorrhage, in a
short time the clot undergoes complete liquefaction, and, hav-
ing been surrounded by a fibrous-tissue capsule, a sort of cyst
results ; or later there may be simply a pigmented scar to
mark the site of the hemorrhage.

Secondary degeneration of the direct and crossed pyramidal
tracts results, when, as is often the case, the hemorrhage has
occurred in the region of the internal capsule; due, it is sup-
posed, to the separation of these motor-nerve fibres from their
trophic centres.

INFLAMMATION.

Acute inflammation of the brain — encephalitis — may occur
in the course of various acute infectious diseases, as typhoid
fever, septicaemia, and influenza. The condition is character-
ized by the formation of localized areas of softening, which are
red or yellow in color, according to the amount of extra vasa ted
blood present.

Microscopically, in these areas, and also in others where
softening is not yet manifest, the bloodvessels are dilated,
engorged with blood, and surrounded with migrated leuko-
cytes. The ganglion-cells and nerve-fibres undergo a granular
and fatty degeneration. In the centre of the area the neurog-
lia undergoes a similar change ; at the periphery, however,
may be noted the formation of new neuroglia cells and fibres.

Suppurative inflammation of the brain is most frequently
associated with a similar inflammation of the meninges. The
condition may also occur in the course of pyaemia, ulcerative
endocarditis, and other septic processes; and in influenza, pneu-
monia, and other infectious diseases ; or it may follow direct
injury, or septic inflammation of the bones of the skull.

The abscess-formations which characterize this condition
may be quite small, or large enough to contain, in one case,
as much as four hundred cubic centimetres of pus. In a large
proportion of cases the abscess is solitary ; multiple abscesses
are generally metastatic.

Chronic inflammation of the brain is characterized, like
chronic inflammation of other organs, by an increase of the

TUBERCULOSIS OF THE BRAIN.

427

connective-tissue elements — the neuroglia, cells and fibres;
and a partial or complete atrophy of the parenchyma — the
ganglion-cells and nerve-fibres. The lesion may be confined
to a lobe. In other cases, especially in drunkards and in
general paralysis of the insane, the greater part of the brain

FIG. 196.

Sarcoma of brain (TJ. S. A. Museum, No. 7983).

may be involved. In still other instances there are multiple
areas of sclerosis irregularly distributed throughout the brain
and cord, the grayish or grayish-pink plaques varying in size
from that of a pea to that of an almond.

Tuberculosis of the brain — the most frequent " tumor " for-
mation— is a common lesion, presenting usually as caseous,
circumscribed nodular masses the size of an egg or larger.

428 DISEASES OF THE NERVOUS SYSTEM.

The lesion exists most frequently in the cerebellum and is
more common in the young than later in life.

Syphilis: Gummata of the brain nearly always originate
primarily in the meninges. A syphilitic endarteritis may also
produce diffuse or circumscribed changes in the brain-tissue.

Tumors of the brain are of especial importance by reason of
the inflammatory and degenerative changes resulting from

FIG. 197.

Sarcoma developed between the hemispheres, posteriorly (U. S. A~TMuseum, No. 8400).

their pressure on the brain- tissue. The glioma is the tumor
most frequently met; it is generally solitary and grows always
from the neuroglia-tissue — never from the pia. fiarcoma oc-
curs next in frequency — generally the round-celled variety.
(Figs. 196 and 197.) Carcinoma may occur as a metastatic
growth in the brain, but never primarily.

DEGENERATIONS OF THE CORD.

429

THE CORD.

HEMORRHAGE.

Hemorrhage is of much less frequent occurrence and much
less extensive — the clot generally not more than one centi-
metre in diameter — than in the brain. The condition is
generally the result of trauma, though it may occur sponta-
neously. When the central canal of the cord is dilated and
filled with blood the term hcematomyelia is employed.

DEGENERATIONS.

FIG. 198. Secondary degenerations occur

in the brain and cord as the
result of any lesion interrupting
the course of nerve-fibres in the
brain, cord itself, or posterior
nerve-roots. These changes are
supposed to be due to the re-
moval of normal trophic influ-
ences arising in the ganglion-
cells from which the nerve-fibres
are cut off. The result is the
destruction of the medullary
sheaths of the fibres, to which is
due their opaque white appear-
ance. Tracts in the cord so

FIG. 199.

Descending degeneration in the pyr-
amidal tract following hemorrhage
into the internal capsule. The di-
rect tract is marked, and is repre-
sented at a lower level than it is
usually seen (F. W. Mott).

The ascending tracts of degeneration in
the cervical enlargement after experi-
mental hemisection of the spinal cord
in the mid-dorsal region. The section
shows well-marked degeneration of
Goll's column, of the direct cerebellar
tract, and of the antero-lateral tracts on
the same side as the lesion (F. W. Mott).

430

DISEASES OF THE NERVOUS SYSTEM

affected have a gray or yellowish-gray color in consequence,
and hence the condition is often spoken of as gray degenera-

FIG. 200.

FIG. 201.

PRIMARY DEGENERATIONS OF THE CORD. 431
FIG. 202.

Sections of the spinal cord at the cervical (Fig. 200), dorsal (Fig. 201), lumbar (Fig.
202), levels showing ascending degeneration, unilateral, in the posterior column
after a gumma involving the second and third lumbar nerve-roots. The relative
extent of the degenerated fibres at the different levels is shown in the sections
(Starr).

tion. In addition, microscopically, there is noted a reduction
in the number of nerve-fibres, and sometimes a new formation
of connective tissue.

A descending degeneration affecting the pyramidal tracts
occurs as the result of hemorrhage or other lesion in the brain,
interrupting the course of the motor fibres (Fig. 198).

Ascending degenerations occur after destruction of the cord
or posterior spinal nerve-roots, or from any cause interrupting
the course of the ascending sensory fibres of the cord, involv-
ing the column of Goll, direct cerebellar, and antero-lateral
tracts (Figs. 199-202).

Primary Degenerations.

Sclerosis of the posterior columns, or locomotor ataxia, is the
most important form of primary degeneration of the cord.
Though the macroscopic and microscopic changes are marked,
and have been carefully studied, the true nature of these

432

DISEASES OF THE NERVOUS SYSTEM.
FIG. 203.

Diagrammatic representation of the supply of the groups of anterior-horn cells by the
radicular branches of the anterior median arteries, showing one group of cells
completely destroyed by occlusion of one of these small vessels, and thus ex-
plaining why in poliomyelitis there is usually permanent loss of movement in
some one or more muscles (F. W. Mott).

FIG. 204.

The lesion in the posterior columns at the first dorsal region in a case of locomotor

ataxia (Starr).

PRIMARY DEGENERATIONS OF THE CORD. 433

alterations is not fully understood. By a majority of pathol-
ogists, however, they are regarded as secondary to disease of
the posterior roots or their ganglion-cells. By many, syphilis
is regarded as the most frequent cause of this condition.

Macroscopically, in well-advanced cases the cord usually
appears atrophied, especially in the region of the posterior
white columns, which are narrow and sunken, and gray or
grayish-yellow in color (Figs. 203 and 204). On trans-

FIG. 205.

€&. J

Section of spinal cord about the eighth dorsal segment (from a case of locomotor
ataxia). There is sclerosis of the postero-external column and atrophy of the
fine plexus of nerve-fibrils surrounding the cells of Clarke's column ; moreover,
a band of sclerosis is seen entering the column instead of the bundle of nerve-
fibres. The cells themselves are atrophied and their processes destroyed. This
case was of interest because, in connection with these lesions, the patient had
well-marked visceral symptoms— gastric crises, bladder troubles, and laryngeal
crisis— in addition to the ordinary ataxic symptoms. X 100 diameters (F. W.
Mott).

verse section these changes are found to be most marked in
the lumbar or dorsal regions — the central gray matter is not
generally affected.

28— Hist.

434 DISEASES OF THE NERVOUS SYSTEM.

Microscopically, the characteristic features are found to be
an increase of the neuroglia-tissue and destruction of the
myelin-sheaths, and later of the axis-cylinder — whether the
nervous tissue or the neuroglia-tissue is primarily affected is
not known (Fig. 205). Similar changes may occur in the
cranial nerves, especially in the optic, and in the spinal nerves.

The prominent clinical feature — inco-ordination — is due to
the interference with the centripetal, nerve-fibres, especially
those coming from the muscles. This explains also the early
loss of muscle-reflexes. Actual loss of muscle-power indicates
implication of the motor tracts in the lateral columns ; and

FIG. 206.

Photo-micrograph of a section of the cervical spinal cord (from a case of amyo-
trophic lateral sclerosis). Degeneration of the crossed pyramidal and direct
tracts and the antero-lateral ground-fibres. The direct cerebellar tracts, the
antero-lateral ascending tracts, and especially the posterior columns, are unaf-
fected. There was almost complete absence of cells and fine nerve-fibre retic-
ulum in the anterior horns; this is observable by the difference in color as
compared with the posterior horns (F. W. Mott).

localized atrophies, which may aifect certain groups of muscles,
if not due to such paralysis, results from the extension of the
disease to the anterior cornua.

Friedreich's disease, or hereditary ataxia, occurs at an early
age, generally in several members of the same family. Ana-
tomically, the characteristic features are degenerative changes
in the posterior and lateral columns, involving the pyramidal
and direct cerebellar tracts.

Spontaneous lateral sclerosis (Erb's spastic paraplegia) is a

PROGRESSIVE SPINAL MUSCULAR ATROPHY. 435

primary degeneration affecting the lateral columns, especially
the pyramidal tracts. The changes usually begin in the
lumbar cord, and are bilateral. The chief clinical character-
istics are paralysis, muscular spasms, and exaggerated muscle-
reflexes ; the first being of course readily accounted for, and
the two latter, in part at least, may be referred to the absence
of the control exercised by the higher centres upon those in
the cord, and transmitted normally through the tracts now
degenerated.

In some cases, to which the term amyotrophic lateral
sclerosis has been applied, the anterior cornua of gray matter
are also involved, adding muscular atrophy to the symptoms
already present (Figs. 206 and 207).

FIG. 207.

The same as previous figure, except that the section is of the seventh to eight dorsal
segments. The pyramidal tracts are sclerosed,and there is considerable degen-
eration in the intermedio-lateral tract (F. W. Mott).

Progressive spinal muscular atrophy (chronic anterior polio-
myelitis) is characterized by a gradual atrophy of the large
ganglion-cells of the anterior cornua ; and clinically by pro-
gressive atrophy and consequent paralysis of the muscular
system — commonly being first manifest in the hand. Though
the degenerative changes affect mainly the ganglion-cells of
the anterior cornua., the motor fibres arising from them, and

436 DISEASES OF THE NEEVOVS SYSTEM.

probably, in most cases, both the direct and crossed pyramidal
tracts are involved. In some instances the pyramidal tracts
in parts of their course may be affected before the anterior
cornua, which could account for the spasmodic rigidity in
localized muscle-groups sometimes seen. Generally, however,
there is no clinical evidence of the involvement of the pyram-
idal tracts.

INFLAMMATION.

Under the term myelitis — inflammation of the cord — is in-
cluded, according to different authors, a great variety of
affections. By many the primary degenerations just briefly
described are included under this heading. To those cases in
which the changes are limited in their longitudinal extent the
term transverse myelitis has been applied, in contradistinction
to others in which a considerable length of the cord is involved :
to which the term poliomyelitis (TTO^OC — gray) has been ap-
plied when the changes are confined to the gray matter alone ;
or leukomyelitis (huxb$ — white), when confined to the white
matter.

Acute transverse myelitis, resulting in softening of the cord
and characterized clinically by paralysis of motion and sensa-
tion below the site of the lesion, may arise without assignable
cause. It may be due to trauma, exposure to cold, or excessive
venery, and certain of the acute infectious diseases have been
regarded as exciting causes.

According to the color of the involved area, several stages
are described — as red and yellow softening, and gray degener-
ation.

At the first stage the tissue is pink from the engorgement of
the bloodvessels, and minute hemorrhages here and there.

Microscopically, the bloodvessels are dilated and surrounded
by migrated leukocytes, the neuroglia-tissue is swollen and its
cells sometimes increased in number. The ganglion-cells are
likewise swollen, and show a diminished staining capacity,
vacuolization, varicosity of their protoplasmic processes, and
dislocation of their nucleus toward the periphery of the cell.

At a later stage the tissue is yellow, pressure-anamia having

ACUTE TRANSVERSE MYELITIS.

437

given rise to fatty degeneration of the exudate and of the
myelin-sheaths of the nerve-fibres. Microscopically, the
nerve-fibres are found to be swollen and granular, and the
myelin-sheaths filled with droplets of fat. Everywhere are
numerous leukocytes, and possibly some neuroglia-cells which
have taken up the disintegrated myelin, and on account of
their appearance have been designated compound granular cells.
The myelitis rarely goes on to suppuration, though the
affected area may undergo complete liquefaction (Fig. 208).

FIG. 208.

a, changes on the eleventh day after section of
a frog's sciatic (Gray).

6, changes on the fifteenth
day after section (Gray).

Usually, however, the fat is absorbed, and, the myelin-
sheaths having been entirely destroyed, a condition of gray
degeneration or softening remains.

438

DISEASES OF THE NERVOUS SYSTEM.

FIG. 209.

Chronic transverse myelitis may follow an acute attack, the
chief characteristic being a marked increase in the neuroglia-
tissue in addition to the changes already noted. Similar
changes may also be produced by chronic compression of the
cord resulting, for instance, from the growth of a tumor in
the meninges (Fig. 209), or the bony deformity produced by
Pott's disease.

Acute anterior poliomyelitis is an acute inflammation of the
anterior cornua of the gray matter of the cord accompanied

by marked systemic disturbances.
On account of its greater frequency
in childhood, the condition is known
clinically as "infantile paralysis,"
though the disease does occur in the
adult, and is recognized as " acute
spinal paralysis." Nothing definite
is known as to its course, though
by many it is regarded as an infec-
tious disease, having a selective
action on the tissues which are
affected.

Macroscopically, characteristic
alterations, which are most marked
in the lumbar and cervical enlarge-
ments, may be entirely absent at an
early stage of the disease, though
the changes consecutive to the cessa-
tion of the acute inflammatory proc-
ess are quite obvious, consisting
of sclerosis and atrophy of the
anterior gray coruna and the
ante ro -lateral white columns.

Microscopically, at an early stage
the bloodvessels of the anterior
cornua are dilated and surrounded
by migrated leukocytes, and there
have also been noted swelling and granular degeneration of
the large ganglion-cells. At a later stage, even within a few
days of the onset of the disease, the ganglion-cells lose their

Meningitis and
pression

3 and beginning
-myelitis from an

dural tumor (Bock).

rom an extra-

ACUTE ANTERIOR POLIOMYELITIS.
FIG. 210. FIG. 211.

439

Anterior cornua from case of poliomyelitis, showing atrophy of the ganglion-
cells. For comparison the appearance of healthy cornua is shown. The small
black triangles represent the cells as they appear under a low magnification
(F. W. Mott).

FIG. 212.

Spinal cord at sixth cervical level, from a case of infantile paralysis. The atrophy of
the right anterior horn, the existence of sclerotic scar-tissue in the horn, as well as
the absence of groups of cells, are shown. The left anterior horn is normal (Starr).

440 DISEASES OF THE NERVOUS SYSTEM.

nuclei and protoplasmic processes, and the cell-body becomes
shrunken and finally entirely disappears. The nerve-fibres of
the anterior roots show fatty degeneration of the myelin-sheaths
and fragmentation of the axis-cylinders (Figs. 210-212).

FIG. 213.

Sarcoma of the spinal cord (Bock).

Of primary tumors the glioma and sarcoma are the types
most frequently encountered (Fig. 213).

INDEX.

Abscess of liver, 394
Acid stains. 25
Actinomycosis, 267

of lungs, 356
Adenocarcinoma, 302
Adenoid tissue, 52, 85
Adenoma, 299

simple, of kidney, 414
Adipose tissue, 52
Adrenal glands, 108
capillaries of, 109
cortex of, 109

zona fasciculata, 109
glomerulosa, 109
reticularis, 109
general structure of, 108
internal secretion of, 110
lymph -passages of, 109
medulla of, 109
sustentacular connective tissue

of, 108
Agminate glands of small intestine,

131

Air- vesicles, 149
Alimentary system, 1 11
Allantois, 191
Alveolar sarcoma, 297
Alveoli, 195
Amnion, 190

Amoeboid movement of cells, 30
Amphi-arthrosis, 200
Amyloid degeneration, 277, 323, 327

of kidney, 412
Anaemia, 312
of brain, 425
local, 270

pernicious, progressive, 313
primary, 312
simple, 313
secondary, 317

Aneurism, 329

cylindrical, 329

fusiform, 329

sacculated, 329
Angeioma, 294

cavernous, 294

lymphangeiomata, 294
Angeiosarcomata, 297
Aphthous stomatitis, 359
Apoplexy, 425
Appendicitis, 385
Appendix vermiformis, 133
Arachnoid, 211
Areolaf tissue, 50
Arteries, 77-79

terminal, 78

tunica adventitia, 78
intima, 77
media, 77

Arterio-sclerosis, 328
Arteritis, 327

chronic, 328
Asiatic cholera, 386
Atelectasis, 336
Atheroma, 328
Atrophy, 284

acute yellow, of liver, 393

of heart, 318

progressive spinal muscular, 435
Attraction-sphere, 27
Axis-cylinder, 207

processes, 205
Axon, 207

Bacillus of Eberth, 386
Bacteria, pathogenic, 269

saprophytic, 269
Basement membranes, 52
Basic stains, 25
Bile-ducts, 136 3

(441)

442

INDEX.

Bile-ducts, inflammation of, 400
-passages, 138
stenosis of, 400
Bladder, 168
calculi in, 418
coats of, 168
fibrous, 169
mucous, 168
muscular, 169
fissure of, 416
hypertrophy of, 416
inflammation of, 416
tuberculosis of, 417
tumors of, 417
Blastoderm, 40
Blood, 65, 91-103
circulation of, 75
-corpuscles, 91
red, 92

alterations in, 310
decay of, 95

difference of, in vertebrate,
functions of, 94
number of, 93
•origin of, 95
structure of, 94
white, 97

consistency of, 97
number of, 97
shape of, 97
size of, 97
structure of, 97
surface of 97
diseases of, 309
anaemias, 312
plethora, 309
oligemia, 309
glands, 67, 104
-plasma, 91
-plates, 103

alterations in, 311
qualitative changes in, 309
Bloodvessels, dilatation of, 251
diseases of, 327
degenerations, 327
arteritis, 327
phlebitis, 330
of kidney, 165
of lung, 146
of salivary glands, 120
of small intestines, 132
of spleen, 105

Bloodvessels of stomach, 128

of thyroid gland, 107
Bone, 56-60
areola>, 58, 59
primary, 58
secondary, 59
calcined, 56
cancellous, 56
-cells, 48, 56
compact, 56
decalcified, 56
development of, 58
cartilaginous, 58
membranous, 59
fibres of Sharpey, 57
lacunae, 57

Howship's, 60
marrow, 57
function, 58
red, 57

cells, 57
yellow, 58
matrix, 56
lamellae, 57
system, 57

Haversian, 57
intermediate, 57
peri-medullary, 57
peripheral, 57
perforating fibres, 58
tissues, 56
cancellous, 56
compact, 56

Bowman, membrane of, 126
Brain, diseases of, 424
ana?mia, 425

cerebral hemorrhage, 425
embolism, 424
hyperaemia, 425
acute, 425
passive, 425
inflammations, 426
acute, 426
chronic, 426
suppurative, 426
syphilis, 428
thrombosis, 424
tuberculosis, 427
tumors, 428
ventricles of, 213
Bright's disease, 403
Bronchi, 147

INDEX.

443

Bronchi, structure of, 148
Bronchial tubes, diseases of, 333
Bronchiectasis, 335
Bronchitis, 333

acute, 333

chronic. 335

fibrinous, 335
Bronchopneumonia, 343
Bronchorrhoea, 335
Brownian movements of cells, 31
Brunner, glands of, 131
Budding, 34
Bursae, 200

Cachectic oedema, 273
Calcareous infiltration, 282, 323,
Calcification, 282
Calculi in bladder, 418
Canal of Petit, 229
Cancrum oris, 360
Capillaries, 80

stomata, 80

Capillary bloodvessels, 263
Capsule of Glisson, 134
Carcinoma, 301

of bladder, 417

of brain, 428

cylindrical-celled, 302

of intestines, 392

of liver, primary, 399
secondary, 400

of mouth, 360

of pancreas, 401

primary, of gall-bladder, 400
of kidney, 414

simplex, 302

squamous-celled, 303

of stomach, 375

of urethra, 419
Cardiac dropsy, 272

hypertrophy, 319
Carotid glands, 106
Cartilage, 52

-cells. 48

cellular, 55

hyaline, 53

of larynx, 143

perichondrium, 54

white fibre-, 54

yellow elastic, 55

327

Casts, 404
cellular, 406
granular, 405
hyaline, 405
waxy, 407

Catarrhal stomatitis, 359
Cavernous angeioma, 294
Cells, 20, 22
body, 24

contents of, 24
bone-, 48
cartilage-, 48
classes of, 22

differentiated or specialized, 23
connective tissue, 23
epithelial, 23
muscle, 23
nerve-, 23
free-living, 22
generalized or undifferentiated,

leukocyte, 23
ova, 23
single, 23
independent, 22
of Claudius, 240

connective-tissue, 23
connective tissue, 47
bone-, 48
cartilage-, 48
fat-, 48
flattened, 48
fusiform, 47
granular, 48
irregular, 48
lamellar, 48
mast-, 48
mucous, 47
neuralgia-, 48
odontoblasts, 48
pigmented, 48
plasma-, 48
round, 47
spherical, 47
stellate, 47
wandering, 49
cortical, 119
cyclosis, 30, 31 -
definition of, 22
of Deiters, 239
epithelial, 23
fat, 48

444

INDEX.

Cells, forms of, 28

disc-shaped, 28

flattened, 28

oval, 28

spherical, 28
free, 64
functions of, 29

motion, 29

nutrition, 29

sensibility, 29
ganglion, 202
granules, 25
gustatory, 119
of Hen sen, 240
of Langerbans, 221
leukocytes, 23
lymphoid, 64
mast-, 48
movements of, 30

amoeboid, 30

Brownian, 31

ciliary, 31

contraction, 30
mucous, 47
muscle, 23, 60
nerve-, 23, 202

of cord, 215
neuralgia, 48
olfactory, 142
origin of, 33
ova, 23
plasma of, 48
processes, 28
properties of, 29
of Purkinje, 213
reproduction of, modes of, 33

budding, 34

direct division, 33

indirect division, karyokinesis or
mitosis, 34

segmentation, 34
single, 23
size of, 29
spaces, 82
spores, 23
structure of, 23

body, 23

cell-wall, 24

centrosome, 23

intimate, 31

nucleus, 23
tactile, 221

Cells, vital properties of, 29
wall, 27

wandering, 49, 64
Cellular cartilage, 55
casts, 406

exudate, function and fate of, 254
fluids, 65
blood, 65
lymph, 65
semen, 65

Cement intercellular, 32
Centrosome, 27

Cerebellar cortex, gray matter of, 213
Cerebellum, 213

superficial portion, 213
Cerebral cortex, gray matter of, 211

hemorrhage, 425
Cerebro-spinal meningitis, 211
Cerebrum, 211

gangl ionic parts of, 212
Chemotaxis, 252
negative, 102
positive, 102
Chlorosis, 312
Chondroma, 292
Chorion, 190
Choroid, 226
Chrematin, 36
Chromatin, 26
Chromophilic granules, 203
Chyle, 103
Cilia, 27

motion of, 28
Ciliary body, 228

movements of cells, 31
Circulatory apparatus, 269
anaemia, local, 270
embolism, 271
hypersemia, 269
active, 269
passive, 270
ischsemia, 270
oedema, 272
thrombosis, 270
system, 75
arteries, 77

tunica adventltia, 78, 79
intima, 77, 79
media, 77, 79
capillaries, 80
diseases of, 318
arteritis, 327

INDEX.

445

Circulatory system, diseases of, atro-
phy, 318

degenerations, 327
degenerative changes, 321
hypertrophy, 319
inflammations, 323
phlebitis, 330
heart, 75

vascular sinuses, 80
veins, 79

Circumvallate papillae of tongue, 118
Cirrhosis of liver, 396
Clitoris, 194

Cloudy swelling degeneration, 281
Coagulation-necrosis, 275
Coccygeal gland, 106
Cochlea, 236
Cohnheim, experiments of, 248

fields of, 61
Colitis, acute, 381
Colloid degeneration, 280
Colostrum, 197
Columnar epithelium, 44
Common ducts, 138
Conjugation, 38
Conjunctiva, 224
Connective tissue, 47
cells. See Cells,
changes, 255
distribution, 47
extracellular elements, 47
of lung, 145
varieties of, 49-60
Cord, spinal, degenerations of, 429
ascending, 431
descending, 431
primary, 431
secondary, 429
hemorrhage of, 429
inflammations of, 436
tumors of 440
Corium, 153
Cornea, 226

epithelial layer of, 226
Corpora cavernosa, 179

lutea, 185

Corpus spongiosum, 180
Corpuscles, concentric. 89
of Hassall, 89
of Krause, 222
of Meissner, 222
of Pacini, 223

Corpuscles, tactile, 221
Cortical cells, 119
Cowper's glands, 179
Crenation, 93
Croupous stomatitis, 359
Crura cerebri, 213
Crypts of tonsil, 122
Crystalline lens, 229
Cutis vera, 153
Cylindrical-celled cancer, 302
Cystic ducts, 138
Cystitis, 416
Cystosome, 24
Cysts, 307

disintegration, 308

of kidnev, 414

retention, 308
Cytolemma, 27
Cytoplasm, 2

Decidua, 191

Degenerations, amyloid, 277, 323, 327,
412

cloudy swelling, 281

colloid, 280

fatty, 277, 327, 412

granular, 281

hyaline, 281, 323

of kidneys, 412

lardaceous, 277

mucoid, 280

parenchymatous, 281, 412

of spinal cord, 429
ascending, 431
descending, 431
primary 431
secondary, 429

waxy, 277

Degenerative changes, 321
Dendrites, 205

functions of, 206
Dentinal fibre, 114

sheath, 114

tubules, 114
Derm is, 153
Development, 33-41

of embryo, 40
Diapedesis, 252
Diath roses, 200
1 Differentiation, 40

446

INDEX.

Diphtheria, 361
Disintegration cysts, 308
Ductless glands, 68, 104
Ducts, common, 71

ejaculatory, 378

interlobular, 70

intermediate, 70

intralobular, 70
Duodenal glands of small intestine,

131

Duodenitis, 381
Dura mater, 211

Ear, 233

external, 234

middle, 234
Eberth, bacillus of, 386
Echinococcus cyst of liver, 400
Ectoplasm, 24
Ectosarc, 24
Ejaculatory ducts, 178
Elements, extracellular, 20, 22, 32, 47

non-cellular, 20, 22

ultimate, 19, 22
Embolism, 271

of brain, 424

Embryo, development of, 40
Emphysema, 336

interstitial, 336

vascular, 336
Empyema, 358
Emulsions, 66
Encephalitis, 426
End-bulbs, 222
Endocarditis, 324

acute, 324

chronic, 325
Endocardium, 75

valves of, 75
Endomysium, 61
Endoplasm, 24
Endosarc, 24

Endothelial sarcomata, 298
Endothelioma of meninges, 424
Endothelium, 42, 46
Enteritis, 380

Eosinophile leukocytes, 100
Epiblast, 40

tissues developed from, 41
Epidermis, 151

Epididymis, 176

canal of, 176
Epiglottis, 143
Epimysium, 61
Epithelioma, 303
of larynx, 333
primary of liver, 399
Epithelium, 42-4(5
columnar, 44
ciliated, 45
simple, 45
stratified, 45
non-ciliated, 44
simple, 44
stratified, 44
function of, 43
glandular, 45
goblet, 45
location of, 42
neuro, 46
pigmented, 46
simple, 44
specialized, 46
neuro-, 46
pigmented, 46
squamous, simple, 43

stratified, 43
structure of, 42
transitional, 44
varieties of, 43
Erectile tissue, 81
Erythroblasts, 58
Erythrocytes, 92
Eustachian tube, 234
Exudate, cellular, function and fate

of, 254

serous, function of, 255
Eye, 224
Eyelids, 233

Fallopian tubes, 186
Fasciae, 200
Fat-necrosis, 276

Fatty degeneration, 277, 3'22, 327
of kidney, 412

glands, 72

infiltration, 177

tissue, 52

Ferrein, pyramids of, 160
Fertilization of ovum, 39

INDEX.

447

Fever, 267

anatomical changes, 269
etiology of, 268
significance of, 269
Fibres, 32

development of, 49
perforating, 57
of Sharpey, 57
white, 49
yellow elastic, 49
Fibroblasts, 47, 263
Fibroma, 290

of kidney, 414
Fibrosis, 286, 345
Filliform papillae of tongue, 118
Fissure of bladder, 416
Flagella, 27

motion of, 28

Fluids, body, 64

cellular, 65

emulsions, 66

chyle, 66

milk, 66

homogeneous, 65

Foetal membrane, 191

appendages, 190

allantois, 191

amnion, 190

chorion, 190

decidua, 191

foetal membrane, 191

placenta, 192

umbilical cord, 193

vesicle, 191
villi, 192

Foliate papillae of tongue, 119
Follicles of Lieberkiihn, 130
Fovea centralis, 233
Friedreich's disease, 434
Fungiform papillae of tongue. 118

Gall-bladder, 138

inflammation of, 400

primary carcinoma of, 400
Ganglia, "216

of posterior roots, 217

sympathetic, 217

typical, 217
Ganglion-cells, 202
Gangrene, 276

! Gangrene of lung, 346
circumscribed, 346
diffuse, 346

Gangrenous stomatitis, 360
Gastrectasia, 366
Gastric ulcers, 372

dangers of, 374
Gastritis, 366
acute toxic, 367
chronic, 368
glandularis atrophica, 370

prolifera, 369
mucipara, 369
purulent, 367
simple acute, 366

Gastro-intestinal tract, diseases of, 359
Gastroptosis, 366
Gemmation, 34
Genital organs, female, 182
mammary glands, 194
ovary, 182
oviducts or Fallopian tubes,

186

uterus, 187
vagina, 193
vulva, 194
male, 172

Cowper's glands, 179
epididymis, 176
penis, 179
prostate gland, 178
seminal vesicles, 177
testicle, 172
vas deferens, 177
Giant-celled sarcoma, 297
Giraldes, organ of, 177
Glanders, 267

of lungs, 356
Glands, 67

adrenal or suprarenal, 108
agminate, 90

of small intestine, 131
of Bartholin, 194
blood, 67, 104
of Brunner, 131
carotid, 106
coccygeal, 106
corpuscles of Hassall, 89
cortex, 89
Cowper's, 179
ductless, 104
functions of, 104

448

INDEX.

Glands, duo'denal, of small intestine,

131

fatty, 72
lachrymal, 233
Luschka's, 106
lymph oid, 67

of small intestine, 131
mammary, 194
medulla, 89
Meibomian, 233
mucous, 71

of tonsils, 122
parotid, 120
prostate, 178
saccular, compound, 70

simple, 70
salivary, 120

inflammation of, 365
sebaceous, 157
secretory, 67
closed, 68
ductless, 68
morphology of, 70
open, 68
saccular, 70
compound, 70
simple, 70
tubular, 70
compound, 70
simple, 70
serous, 71
solitary, 90
sublingual, 121
submaxillary, 122
thy m us, 88
thyroid, 107
of tongue, 117
tubular, compound, 70

simple, 70
of Tyson, 180
uterine, 188

Glandular epithelium, 45
Glioma, 306

of brain, 428
Glisson, capsule of, 134
Goblet epithelium, 45
Graafian follicles, 184
Granular casts, 405
degeneration, 281
Granulation tissue, 262
Granules, of cells, 25
basophile, 25

Granules, colorless, 25
Dobie's, 62
Ehrlich's division, 25
eosinophile, 25
neutrophile, 25
oxyphile, 25
pigmentary, 25
Granulomata, infective, 264
actino mycosis, 267
glanders, 267
leprosy, 267
rhinoscleroma, 267
syphilis, 267
tuberculosis, 264
Granuloplasm, 24
Gustatory cells, 119

Hsemaglobin, amount of, 311
Hsemothorax, 356
Hairs, 154
bulb, 154
cortex of, 155
cuticle, 155
follicle, 155
medulla, of, 155
roots, 154
Healing by first intention, 259

by second intention, 260
Heart, 75

and pericardium, diseases of, 318
atrophy, 318

degenerative changes, 321
hypertrophy, 319
inflammations, 323
valves of, 75

Hemorrhagic infarcts of lungs, 339
Henle, layer of, 156
Henle's loop, 164

ascending limb of, 165
descending limb of, 164
Hensen, line of, 62
Hepatic artery, 136
ducts, 138
veins, 136
Hernia, 379
Histologic structures, analysis of, 19

of man, 19
technique, 20
Homogeneous fluids, 65
Howship's lacunae, 60

INDEX.

449

Hyaline cartilage, 53

casts, 405

degeneration, 281, 323

matrix, 32
Hyaloplasm, 24
Hydronephrosis, 416
Hydrothorax, 356
Hymen, 194
Hypera?mia, 269

active, 269

of brain, 425
acute, 425
passive, 425

passive, 270, 337
of kidneys, 403
of liver, 393
Hypertrophy, 285

of bladder, 416

cardiac, 319
causes of, 319

causes, 285
Hypoblast, 40

tissues developed from, 41
Hypoplasia, 284, 285

of heart, 318

Infarcts, 271

Infective granulomata of lung, 347
Infiltration, calcareous, 282
and degenerations, 276
fatty, 277
pigmentary, 283

extrinsic, 284

intrinsic, 283
Inflammation, 247
of bile-ducts, 400
of bladder, 416
of brain, 426

acute, 426

chronic, 426

suppurative, 426
of cord, 436
definition of, 247
of gall-bladder, 400
interstitial, 259
of liver, 394

acute purulent, 394

chronic interstitial, 396
of meninges, 420
of pancreas, 401

Inflammation, parenchyinatous, 259
of pelvis of kidney, 415
of peritoneum, 401
productive, 259
purulent, 256
suppurative, 256
of urethra, 418
variations in type of, 255
Interlobular ducts, 70

septa, 70

Intermediate duct, 70
Interstitial emphysema, 336

inflammation, 259
Intestines, acquired deformities and

displacements of, 379
congenital deformities and displace-
ments of, 378
inflammations of, 380
acute colitis, 381
appendicitis, 385
duodenitis, 381
enteritis, 380
specific, 386

Asiatic cholera, 386
syphilis, 391
tuberculosis, 390
typhoid fever, 386
large, 132

muscular coat of, 132
small, 128 .

agminate glands of, 131
bloodvessels of, 132.
duodenal glands of, 131
lymphatic vessels of, 132
lymphoid glands of, 131
mucous membrane of, 129
muscular coat of, 131
muscularis mucosse, 131
nerves of, 132
subepithelial connective tissue,

130

submucosa, 131

serous or peritoneal coat of, 132
walls of, 128
tumors of, 392
Intralobular capillaries, 137
ducts, 70
veins, 137

Intussusception, 380
Iris, 228
Irritants, 256
Ischsemia, 270

450

INDEX.

Karyokinesis, 26, 34
Kidneys, 158

bloodvessels of, 165
cortex of, 160
diseases of, 403

Bright's disease, 403
cysts, 414
degenerations, 412
amyloid, 412
fatty, 412

parenchymatous, 412
granulomata, specific, 413
syphilis, 413
tuberculosis, 413
hypereemia, passive, 403
nephritis, acute parenchymatous,

407

chronic, 410
interstitial, 411
parenchymatous, 410
tumors, 414

general structure of, 158
medulla of, 158
pelvis of, 1 68
inflammation of, 415
wall of, 168
sustentacular connective tissue of,

160

uriniferous tubules of, 162
Krause, membrane of, 62
tactile corpuscles of, 222

Lachrymal canals, 233

gland, 233
Lactation, 194
Langerhans' bodies, 140

cells of, 221

Lardaceous degeneration, 277
Laryngitis, acute, 332

chronic, 333
Larynx, 143
cartilages of, 143

diseases of, 332

epithelioma, 333

laryngitis, 332

papillomata, 333

sarcoma, 333

syphilis, 333

tuberculosis, 333

Larynx, ligaments of, 143
mucous membrane of, 143
epithelial lining, 143
submucosa, 143
tunica propria, 143
Leiomyoma of kidney, 414
Lei )inyomata, 305
Leprosy, 267

of lungs, 356
Leptomeningitis, 421
Leukaemia, 314
Leukocyte, 23

Leukocytes, alterations in, 311
cell-bodies of, 98
nuclei of, 98
number of, 97

origin and development of, 102
structure of, 97
varieties of, 98
eosinophile, 100
large mononuclear, 99
polymorphonuclear or neutro-

phile, 100

small mononuclear, 99
transitional, 99
vital properties and functions of,

101

Leukocythsemia, 314
Leukocytosis, 311
Lieberkiihn, follicles of, 130
Ligament, suspensory, 229
Ligaments of larynx, 143
Linin, 26
Lipoma, 291

of kidney, 414
I Liquefaction-necrosis, 276
I Liquor sanguinis, 91

seminis. 181
Liver, 133
-cells, 136
diseases of, 393

atrophy, acute yellow, 393
hypersemia, 393
inflammations, 394
syphilis, 399
tuberculosis, 399
tumors, 399

general structure of, 134
lobules of, 136
sustentacular or connective tissue

134
Localized cedemas, 273

INDEX.

451

Locomotor ataxia, 431
Lungs, 145

bloodvessels of, 146
connective tissue of, 145
diseases of, 336
actinomycosis, 356
atelectasis, 336
emphysema, 336
gangrene, 346
glanders, 356
hemorrhagic infarct, 339
hypersemia, passive, 337
leprosy, 356
oedema, 338
pneumonia, chronic interstitial,

345

lobar, 339
lobular, 343
syphilis, 355
tuberculosis, 347
tumors, 356
lymphatics of, 147
nerves of, 147
pyramidal lobules of, 145
Luschka's gland, 106
Lymph, 65, 82, 103
-cords, 87
-corpuscles, 103
follicles, 85
-sinuses, 89
medullary, 87
peripheral, 87
-spaces, 82

of Fontana, 228
Lymphangeioma, 294
Lymphatic glands, 86
capsule of, 87
circulation through, 88
cortex of, 88
elements of, 86
functions of, 90
medulla, 88
origin of, 83
vessels of, 87
afferent, 87
efferent, 88
system, 82
action of, 82
lacteals of, 84

morphologic elements of, 82
origin of, 83
vessels of, 82, 84

Lymphatic system, vessels of, coats, 84

valves, 85
vessels, 84

of small intestine, 132
of spleen, 106
of stomach, 128
Lymphatics of lung, 147
of salivary glands, 120
of thyroid gland, 108
Lymphoid cells, 64

of tonsil, 122
glands, 67

of small intestine, 131
tissue of, 52, 85
cells of, 85
diffuse, 85
functions of, 90
meshes, 85
nodules, 85

Macula lutea, 233
Malpighi, pyramids of, 158
Malpighian body, 162

arrangement and function, 163
corpuscles, 106
Mammary glands, 194
secretion of, 196
sustentacular connective tissue

of, 195

Margination, 250
Marrow, function of, 58
red, 57
yellow, 58
Mast-cells, 48
Maturation of ovule, 38
Medulla oblongata, 213
Medullary sheath, 208
Medullated nerve-fibres, 207
Meibomian glands, 233
Meissner, tactile corpuscles of, 221
Melanotic sarcoma, 298
Membranes, 51
basement, 52
of Bowman, 226
distant, 51
of Krause, 62
mucous, 72
epithelium, 72
muscularia mucosae, 72
secretion, 73

452

INDEX.

Membranes, mucous, submucosa, 72

tunica propria, 72
of Nasmyth, 114
of Reissner, 237
serous, 73

connective tissue, 73
endothelium, 73
parietal, 73
subserous tissue, 73
visceral, 73

Meninges, diseases of, 420
leptomeningitis, 421
pachymeningitis, 420
chronic, 420
hemorrhagic, 420
syphilis, 424
tuberculosis, 423
tumors, 424
Mesoblast, 40
Metakinesis, 37
Micropyle, 41

Microscopical appearances of inflamed
animal membranes, 248
first stage, 248
second stage, 249
third stage, 250
Mineral matters, 32
Mononuclear leukocytes, large, 99

small, 99
Mouth, 111
diseases of, 359
stomatitis, 359
syphilis, 360
thrush, 360
tuberculosis, 360
tumors, 360

mucous membrane of, 111
of epithelial layer, 111
of submucosa, 112
of tunica propria, 112
Mucoid degeneration, 280
Mucosa, 72
Mucous cells, 47
glands, 71

of tongue, 117
membranes 72
of larynx, 143
of mouth, 111
of nasal fossae, 141
of oesophagus, 125
of pharynx, 124
of small intestine, 129

Mucous membranes of tongue, 116
of trachea, 144
of uterus, 187
Mumps, 365
Muscle cells, 60
cardiac, 62

involuntary or non-striated, 63
striated or striped, 60
voluntary, 198

motor end-plates of, 320
Muscular coat of large intestine, 132

of urethra, 170
structures, 198
substance of tongue, 116
Myelitis, acute transverse, 436

chronic transverse, 438
Myeloid sarcomata, 297
Myeloplaxes, 51
Myocarditis, 323
Myocardium, 75
Myoma, 304

leiomyomata, 305
rhabdomyomata, 304
Myomalacia cordis, 323
Myxoma, 291

Nails, 157

root of, 157
Nasal fossae, 141

mucous membrane of, 141
olfactory portion, 142
respiratory portion, 142
passages, diseases of, 332
rhinitis, 332
syphilis, 332

Nasmyth, membrane of, 114
Necrosis, 274
varieties of, 275
caseation, 276
coagulation, 275
fat, 276
gangrene, 276
liquefaction, 276

Nephritis, acute parenchymatous, 407
chronic, 410
interstitial, 411
parenchymatous, 410
Nerves, 217

arrangement of, 217
Nerve-cells, 202
of spinal cord, 215

INDEX.

453

Nerve-centres, 209

-fibres, 207

mednllated, 207
non-medullated, 208

filaments of salivary glands, 120

of lung, 147

of small intestine, 132

-terminals, 218
classes of, 218

-tissue, 64

Nervous system, 202
diseases of, 420
division of, 202
Neuraxons, 205
Neurilemma, 208
Neurites, 205

function of, 206
Neuro-epithelium, 46
Neuroglia, 209

-cells, 48

Neurokeratin, 208
Neuroma, 306
Neurons, 64, 206
Neuroplasm, 203
Neurosome, 203
Neutral stains, 25
Neutrophile leukocytes, 100
Nipple, 196
Nodes of Ranvier, 208
Noma, 360

Non-medullated nerve-fibres, 208
Nuclear fibrils, 26

matrix, 26

membrane, 26
Nuclei, 23, 26

function of, 27

location of, 26

shape of, 26

size of, 27

structure of, 26
Nucleolus, 203
Nutrition, pathology of, 274

Odontoblasts, 48
(Edema, 272
of lungs, 338
varieties of, 272
cachectic, 273
cardiac, 272
localized, 273

(Edema, renal, 273
(Esophagus, 125

inflammation of, 365

mucous membrane of, 125
epithelium, 125
submucosa, 125
tunica propria, 125

muscular layer, 125
Olfactory cells, 142

terminals, 224
Oligemia, 309
Oogenesis, 186
Organs, 74

cells of, 74

of Corti, 235, 238

parenchyma 74

sustentacular tissue, 74
Ossification, 58
Osteoblasts, 59
Osteoclasts, 58
Osteoma, 293
Ova, 23, 64, 183
Ovary, 182

epithelial covering of, 183

stroma of, 183
Oviducts, 186
Ovulation, 184
Ovule, 38, J84

fertilization of, 39

maturation of, 38

structure of, 38
Oxyphile leucocytes, 100

Pachymeningitis, 420

chronic, 420

hemorrhagic, 420
Palate, soft, 124
Pancreas, 138

atrophy of, 401

carcinoma of, 401

connective tissue of, 138

inflammation of, 401
Papilla? of tongue, 117

circumvallate, 118

filiform, 118

foliate, 119

fungiform, 118
Papilloma, 299

of bladder, 417
Papillomata of larynx, 333

454

INDEX.

Parathyroids, 108
Parenchymatoufc. degeneration, 281

of kidney, 412
inflammation, 259
Parotid gland, 120
Pathogenic bacteria, 269
Pathology, human, 243

modern or cellular, 244
Pelvis of kidney, 168

wall of, 168
Penis, 179
Peptic or cardiac glands of stomach,

Pericarditis, 326
Pericardium, 76
fibrous, 76
serous, 76
Perimysium, 61
Periosteum, 57
Peritoneum, 133
inflammation of, 401
tuberculosis of, 402
Peritonitis, 401
chronic, 402
Peyer's patches, 131
Phagocytosis, 101, 252
Pharyngeal aponeurosis, 124

tonsil, 124

Pharyngitis, pseudomembranous, 361
Pharynx, 124, 143
diseases of, 361
diphtheria, 361
pseudomembranous pnaryngitis,

361
simple catarrhal inflammation,

361

tonsillitis, 363
mucous membrane of, 124
epithelial lining, 124
lymphoid nodules, 124
submucosa, 124
tunica propria, 124
walls of, 124
Phlebitis, 330
chronic, 331
Phthisis, acute, 350
chronic, 353
fibroid, 354
Pia mater, 211
Pigmentary infiltration, 283
extrinsic, 284
intrinsic, 283

Pigmented epithelium, 46
Pineal body, 110
Pituitary body, 110

anterior lobe of, 110
posterior lobe of, 110
Placenta, 192
Plasma-cells, 48
Plethora, 309
Pleura, 150
diseases of, 356
empyema of, 351
hsemothorax, 356
hydrothorax, 356
pleuritis, 357
pneumothorax, 356
Pleuritis, 357
fibrinous, 357
serofibrinous, 357
Plexus of Auerbach, 132

of Meissner, 132
Pneumonia, 339

chronic interstitial, 345
lobar, 339

division of process. 340
etiology of, 340
lobular, 343
etiology of, 343
lesions of, 344
Pneumothorax, 356
Polar body, 49
corpuscle, 27
Poliomyelitis, acute anterior, 438

chronic anterior, 435
Polymorphonuclear leukocytes, 100
Polynuclear leukocytes, 100
Pons, 213
Portal vein, 136
Productive inflammation, 259
Pronucleus, female, 39

male, 40
Prostate gland, 178

sustentacular connective tissue,

178

Protoplasm, 22
granules, 24, 25
vacuoles, 24

Protoplasmic processes, 205
Pseudomembranous pharyngitis, 361

stomatitis, 359
Purkinje, cells of, 213
Purulent inflammation, 256
Pyelitis, 415

INDEX.

455

Pyelo-nephritis, 415
Pyloric glands of stomach, 127
Pyonephrosis, 415
Pyramidal lobules of lung, 415
Pyramids of Ferrein, 160
'of Malpighi, 158

Quinsy, 364

230

33, 41

Radiating fibres of Miiller,
Ranvier, nodes of, 208
Rectum, 133
Red-marrow, 57
Renal calculi, 416

dropsy, 273
Repair, 259
Reproduction,

of cells, 33

sexual, 38

Reproductive system, 172
Respiratory organs, diseases of, 332

system, 141

general considerations of, 141
Retention cysts, 308
Retiform tissue, 52
Retina, 230
Rhabdomyomata, 304
Rhinitis, 332

acute, 332

chronic, 332
Rhinoscleroma, 267
Round-celled sarcomata, 295

Saccular glands, compound, 70

simple, 70
Saccule, 235
Saliva, 122
Salivary glands, 120

blo'odvessels of, 120

ducts of, 120

general structure of, 120

inflammation of, 365

lymphatics of, 120

nerve filaments of, 120

sustentacular connective tissue

of, 120
Salter, incremental lines of, 115

Saprophytic bacteria, 269
Sarcoleinma, 60
Sarcoma, 294

alveolar, 297

angeiosarcomata, 297

of brain, 428

endothelial, 298

giant-celled or myeloid, 297

of larynx, 333

melanotic, 298

of mouth, 360

primary, of kidney, 414

round-celled, 295

spindle-celled, 296

of urethra, 419
Sarcoplasm, 61
Sarcous discs. 62

elements. 62

substance, 61
Scala media, 237
Schreger, lines of, 115
Sclerosis, amy trophic lateral, 435

of posterior columns, 431

spontaneous lateral, 434
Sebaceous glands, 157
Secretions, external, 68

internal, 68
Secretory glands, 67

morphology of, 70
Segmentation, 34
Semen, 65, 181
Semicircular canals, 236
Seminal vesicle, 177
Serous exudate, functions of, 255

glands, 71

of tongue, 117

membranes, 73
Sertoli, columns of, 174
Sharpey, fibres of, 57
Sneath'of Schwann, 208
Simple fluids, 65
Sinuses-lymph, 87

vascular, 80

venous, 79

Skeletal structures, 198
Skin, 151
Soft palate, 124
Specialized epithelium 46
Spermatogenesis, 174
Spermatozoa, 181
Spheroidal-celled cancer, 302
Spinal cord, 214

,56

INDEX.

Spinal cord, hemorrhage of, 429

nerve cells of, 215
Spindle-celled sarcoma, 296
Spiral ganglion, 240
Spleen, 104

bloodvessels of, 105
function of, 106
general structure, 104
lymphatic vessels of, 106
sustentacular framework of, 105
Splenic pulp, 105
Spongioplasm, 24
Spores, 23
Squamous-celled cancer, 303

epithelium, 43
Stains, acid, 24
basic, 24
neutral, 25
Stomach, 126

bloodvessels of, 128
diseases of, 366
gastrectasia, 366
gastritis, 366
acute toxic, 367
chronic, 368
purulent, 367
simple acute, 366
gastroptosis, 366
tumors, 375
ulcers, 371

lymphatic vessels of, 128
mucosa of, 126

epithelial lining, 126
muscular coat, 128
peptic or cardiac glands, 126
pyloric glands, 127
serous or peritoneal coat, 128
subepithelial connective tissue of,

127

submucosa, 128
walls of, 126
Stomatitis, 359
aphthous, 359
catarrhal, 359
croupous, 359
gangrenous, 360
pseudomembranous, 359
ulcerous, 359
Stratum corneum, 153
granulosum, 152
lucidum, 153
Malpighii, 152

Sublingual gland, 121
Submaxillary gland, 122
Submucosa, 72

Suppurative inflammation, 256
Suprarenal glands. See Adrenal

glands.

Suspensory ligament, 229
Sustentacular tissue, 87
Sweat-glands, 154
Synarthrosis, 200
Synovial membranes, 199
Syphilis, 267

of brain, 428

of intestines, 391

of kidneys, 413

of larynx, 333

of liver, 399

of lungs, 355

of meninges, 424

of mouth, 360

of nose, 332

Tactile cells, 221
Taste-buds, 119

-terminals, 224

Technique, dyes, 20

general, 21

nuclear, 20

histological, 20

sections, 20
Teeth, 112

crusta petrosa, 114

dentine, 114

development of, 115

enamel of, 113

general structure of, 112

pulp-cavity, 115
Teledendrites, 205
Tendons, 198
Tendon-sheaths, 199
Teratoma, 307
Terminal bronchioles, 148
Testicle, 172

seminiferous tubules, 173

sustentacular connective tissue of,

173

Thoracic duct, 85
Thrombosis, 270

appearance and structure of, 270

of brain, 424

INDEX.

457

Thrombosis, cause of, 271
Thrush, 360
Thymus gland, 88
Thyroid gland, 107

bloodvessels of, 107
functions of, 108
lymphatics of, 108
sustentacular connective tissue of,

107

Tissues, 20, 22, 42
adenoid, 85
adipose, 52
areolar, 50
classes of, 42

connective tissue, 47
endothelium, 42, 46
epithelium, 42
free cells and body fluid, 64
muscles. 60
nerve-, 64

connective, varieties of, 49
adipose, 52
areolar, 50
bone, 56
cartilage, 52
membrane?, 51
basement, 52
distant, 51
mucous, 49
retiform, 52
white fibrous, 51
yellow elastic, 51
elements of, 21
erectile, 81
fatty, 52
lymphoid, 85
mucous, 49
nerve-, 64
retiform, 52
adenoid, 52
lymphoid, 52
sustentacular, 87
white fibrous, 51
yellow elastic, 51
To'ngue, 116

general structure of, 116
glands of, 117
mucous, 117
serous, 117

lymphoid tissue of, 117
mucous membrane of, 116
epithelial covering, 116

Tongue, mucous membrane, submu-

cosa, 116
tunica propria, 116

muscular substance of, 116

papilla? of, 117
circumvallate, 118
filiform, 118
foliate, 119
fungiform, 118
Tonsillitis, 363
Tonsils, 90, 122

crypts of, 1 22

lyraphoid cells of, 122

mucous glands of, 122
Trachea, 144

mucous membrane of, 144
Transitional epithelium, 44

leukocytes, 99
Tuberculosis, 264

of bladder, 417

of brain, 427

caseation, 266

fibroid transformation, 266

giant-cell, 266

histological tubercle, 264

of intestines, 390

of kidneys, 413

of larynx, 333

of liver, 399

of lungs, 347

acute miliary. 349

of meninges, 423

of mouth, 360

of peritoneum, 402
Tubular glands, compound, 70

simple, 70
Tumors, 286

of bladder, 417

of brain, 428

classification of 287
histological, 2S8

of cord, 440

definition of, 286

etiology of, 286

of intestines, 392

of kidneys, 414

of liver, 399

of lungs, 356

of meninges, 424

of mouth, 3(>0

of stomach, 375

of urethra, 419

458

INDEX.

Tunica adventitia, 78, 79

intima, 77, 79

media, 77, 79
Typhoid fever, 386
Tyson, glands of, 180

Ulcer of stomach, 371
Umbilical cord, 193

vesicle, 191
Ureter, 168

coats of, 168
fibrous, 168
mucous, 168
muscular, 168
Urethra, 169

female, 169

inflammation of, 418

male, 170

muscular coat of, 170

stricture of, 419

tumors of, 419
Urethritis, acute, 418

chronic, 418
Urinary bladder, 416

organs, 158

diseases of, 403
Urine, 171

secretion of, 167
Uriniferous tubule, 162

neck of, 1 64
Uterine glands, 188
Uterus, 187

cervix of, 189

mucous membrane of, 187

muscular coat of, 188
Utricle, 235

Vagina, 193

Varix, 331

Vas deferens, 177

Vasa eflerentia, 175

Vascular emphysema, 336

sinuses, 80
Veins, 79

valves, 79

tunica adventitia, 79
intima, 79
media, 79
Venous sinuses, 79
Ventricles of brain, 213
Vessel walls, increased permeability

of, 251

Vestibule of ear, 235
Villi, 129, 192

function of, 130
Vitreous body, 230
Volvulus, 380
Vulva, 194

Wagner, tactile corpuscles of, 221
Wandering cells, 49, 64
Watney's nodes, 130
Waxy casts, 407

degeneration, 277
White fibres, 49

tibro-cartilage, 54

fibrous tissue, 51

Yellow elastic cartilage, 55
fibres, 49
tissue, 51
marrow, 58

CATALOGUE OF PUBLICATIONS OF

LEA BROTHERS & COMPANY,

TOG, 708 & 710 Pansom St., Philadelphia.
1H Fifth Ave. (Cor. 18th St.), New York.

The books in the annexed list will be sent by mail, post-paid, to any Post-Office in the
United States, on receipt of the printed prices.

INDEX.

ANATOMY.__Gray, p. 11 ; Treves, 30 ; Gerrish, 11; Brockway, 4.

DICTIONARIES. Dunglison, p. 8 ; Duane, 8 ; National, 4.

PHYSICS. Draper, p. 8 ; Robertson, 24 ; Martin & Rockwell, 20.

PHYSIOLOGY. Foster, p. 10; Chapman, 5; Schofield, 25; Collins
& Rockwell, 6. [Luff, 19 ; Rerasen, 24.

CHEMISTRY. Simon, p. 26 ; Attfield, 3 ; Martin & Rockwell, 20;

PHARMACY. Caspari, p. 5. [Brace, 4 : Scbleif, 25.

MATERIA MEDICA. Calbretb, p. 6 ; Maisch, 19 ; Farquharson, 9 ;

DISPENSATORY. National, p. 21.

THERAPEUTICS. Hare, p. 13 ; Fothergill, 10 ; Whitla, 31 ; Hayem
& Hare, 14 ; Bruce, 4 ; Schleif, 25 ; Cashny, 6.

PRACTICE. Flint, p. 9 ; Loomis & Thompson, 19 ; Malsbary, 20.

DIAGNOSIS. Musser, p. 21 ; Hare, 12; Simon, 25; Herrick, 15; Hutchi-
son & Rainey, 16 ; Collins, 6.

CLIMATOLOGY. Solly, p. 26 ; Hayem & Hare, 14.

NERVOUS DISEASES. Dercum, p. 7 ; Gray, 11 ; Potts, 23.

MENTAL DISEASES. Clouston, p. 5 ; Savage, 24 ; Folsorn, 10.

BACTERIOLOGY. Abbott, p. 2 ; Vaughan & Novy, 30 ; Senn's
(Surgical), 25. Park, 22 ; Coates, 6. [Vale, 21.

HISTOLOGY. Klein, p. 17 ; Schafer's, 25 ; Dunham, 8 ; Nichols &

PATHOLOGY. Green, p. 12; Gibbes, 10; Coats, 6; Nichols & Vale, 21

SURGERY. Park, p. 22 ; Dennis, 7 ; Roberts, 24 ; Ashhurst, 3 ; Troves, 29 ;
Cheyne & Burghard, 5 ; Gallaudet, 10.

SURGERY— OPERATIVE. Stimson, p. 27 ; Smith, 26 ; Treves, 29.

SURGERY— ORTHOPEDIC. Young, p. 31 ; Gibney, 10.

SURGERY— MINOR. Wharton, p. 30. [BalleDger &

FRACTURES and DISLOCATIONS. Stimson, p. 27. [Wippern, 3.

OPHTHALMOLOGY. Norris & Oliver, p. 21 ; Nettleship, 21 ; Juler, 17;

OTOLOGY. Politzer, p. 23; Burnett, 5; Field, 9; Bacon, 4.

LARYNGOLOGY and RHINOLOGY. Coakley, p. 6 ;

DENTISTRY. Essig (Prosthetic), p. 9 ; Kirk (Operative), 17 ; Ameri-
can System. 2 ; Coleman, 6; Burchard 4.

URINARY DISEASES. Roberts, p. 24 ; Black, 4 ; Morris, 20.

VENEREAL DISEASES. Taylor, p. 28 ; Hayden, 14 ; Cornil, 6 ;
Likes, 19.

SEXUAL DISORDERS. Fuller, p. 10 ; Taylor, 29.

DERMATOLOGY. Hyde, p. 16 ; Jackson, 16 ; Pye-Smith, 24 ; Mor-
ris, 20 ; Jamieson, 16 ; Hardaway, 12 ; Grindon, 12.

GYNECOLOGY. American System, p. 3 ; Thomas & Maude", 29
Emmet, 9 ; Davenport, 7 ; May, 20 ; Dudley, 8 ; Crockett, 6.

OBSTETRICS. American System,' p. 3 ; Davis, 7 ; Parvin, 22 ; Play-
fair, 23 ; King, 17 ; Jewett, 17 ; Evans, 9.

PEDIATRICS. Smith, p. 26 ; Thomson, 29 ; Williams, 31 ; Tuttle, 30.

HYGIENE. Egbert, p. 9 ; Richardson, 24 ; Coates, 6.

MEDICAL JURISPRUDENCE. Taylor, p. 28.

QUIZ SERIES, POCKET TEXT-BOOKS and MANUALS.

Pp. 18, 25 and 27.
9.1.9

2 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

ABBOTT (A. C.). PRINCIPLES OF BACTERIOLOGY: a Practical
Manual for Students and Physicians. New (5th) edition thoroughly
revised and greatly enlarged. In one handsome 12mo. vol. of 585 pages,
with 109 engrav., of which 26 are colored. Just ready. Cloth, $2.75, net.

One of its most attractive charac-
teristics is that the directions are so
clearly given that anyone with a
moderate amount of laboratory train-
ing can, with a little care as to
detail, make his experiments suc-

cessfully. To those who require a
condensed yet nevertheless complete
work upon Bacteriology we most
cordially recommend it. — The Thera-
peutic Gazette.

AMERICAN SYSTEM OF PRACTICAL. MEDICINE. A SYS-
TEM OF PRACTICAL MEDICINE. In contributions by Various
American Authors. Edited by ALFRED L. LOOMIS, M.D., LL.D.,
and W. OILMAN THOMPSON, M. D. In four very handsome octavo
volumes of about 900 pages each, fully illustrated. Complete work
now ready. Per volume, cloth, $5; leather, $6; half Morocco, $7.
For sale by subscription only. Prospectus free on application.

Every chapter is a masterpiece of
completeness, and is particularly ex-
cellent in regard to treatment, many
original prescriptions, formulae,
charts and tables being given for the
guidance of the practitioner.

"The American Svstem of Medi-

cine" is a work of which every
American physician may reasonably
feel proud, and in which every prac-
titioner will find a safe and trust-
worthy counsellor in the daily re-
sponsibilities of practice. — The Ohio
Medical Journal.

AMERICAN SYSTEM OF DENTISTRY. In treatises by various
authors. Edited by WILBUR F. LITCH, M.D., D.D.S. In three very
handsome super-royal octavo volumes, containing about 3200 pages,
with 1873 illustrations and many full-page plates. Per vol., cloth,
$6; leather, $7 ; half Morocco, $8. For sale by subscription only. Pros-
pectus free on application to the Publishers.

AMERICAN TEXT-BOOKS OF DENTISTRY. In Contribu-
tions by Eminent American Authorities. In two very handsome
octavo volumes, richly illustrated :

PROSTHETIC DENTISTRY. Edited by CHARLES J. ESSIG, M.D.,
D.D.S., Professor of Mechanical Dentistry and Metallurgy, Department
of Dentistry, University of Pennsylvania, Philadelphia. 760 pages,
983 engravings. Cloth, $6 ; leather, $7. Net.

No more thorough production will I It is up to date in every particular.
be found either in this country or in It is a practical course on prosthetics
any country where dentistry is un- ; which anv student can take up dur-
derstood as a part of civilization. —
The International Dental Journal.

any student can take up
ing or after college. — Dominion Den-
tal Journal.

OPERATIVE DENTISTRY. Edited by EDWARD C. KIRK, D.D.S. ,
Professor of Clinical Dentistry, Department of Dentistry, University
of Pennsylvania. 699 pages, 751 engravings. Cloth, $5.50 ; leather,
$6.50. Net. Just ready.

Written by a number of practi-
tioners as well known at the chair
as in journalistic literature, many of
them teachers of eminence in our
colleges. It should be included in
the list of text-books set down as
most useful to the college student,—
The Dental News,

It is replete in every particular
and treats the subject in a progressive
manner. It is a book that every
progressive dentist should possess,
and we can heartily recommend it
to the profession, — The Ohio Dental
Journal,

LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK. 3

AMERICAN SYSTEMS OF GYNECOLOGY AND OBSTET-
RICS. In treatises by the most eminent American specialists. Gyne-
cology edited by MATTHEW D. MANN, A. M., M. D., a^d Obstetrics
edited by BARTON C. HIRST, M. D. In four large octavo volumes
comprising 3612 pages, with 1092 engravings, and 8 colored plates. Per
volume, cloth, $5 ; leather, $6 ; half Russia, $7. For sale by subscrip-
tion only. Prospectus free on application to the Publishers.

AMERICAN TEXT-BOOK OF ANATOMY. See Gerrish, page 11.

ALLEN (HARRISON). A SYSTEM OF HUMAN ANATOMY;
WITH AN INTRODUCTORY SECTION ON HISTOLOGY, by
E. O. SHAKESPEARE, M.D. Comprising 813 double-columned quarto
pages, with 380 engravings on stone, 109 plates, and 241 wood cuts
in the text. In six sections, each in a portfolio. Price per section, $3.50.
Also, bound in one volume, cloth, $23. Sold by subscription only.

A PRACTICE OF OBSTETRICS BY AMERICAN AU-
THORS. See Jeirett, page 17.

A TREATISE ON SURGERY BY AMERICAN AUTHORS.

FOR STUDENTS AND PRACTITIONERS OF SURGERY AND
MEDICINE. Edited by ROSWELL PARK, M.D. See page 22.

ASHHURST (JOHN, JR.). THE PRINCIPLES AND PRACTICE
OF SURGERY. For the use of Students and Practitioners. Sixth
and revised edition. In one large and handsome octavo volume of
1161 pages, with 656 engravings. Cloth, $6; leather, $7.

As a masterly epitome of what has j text-book, we do not know its equal,
been said and "done in surgery, as a It is the best single text-book of
succinct and logical statement of the surgery that we have yet seen in this
principles of the subject, as a model country. — New York Post- Graduate.

A SYSTEM OF PRACTICAL. MEDICINE BY AMERICAN
AUTHORS. Edited by WILLIAM PEPPER, M. D., LL. D. In five
large octavo volumes, containing 5573 pages and 198 illustrations. Price
per volume, cloth, $5 ; leather $6 ; half Russia, $7. Sold by subscrip-
tion only. Prospectus free on application to the Publishers.

ATTFIELD (JOHN). CHEMISTRY : GENERAL, MEDICAL AND

PHARMACEUTICAL. New (16th)' edition, specially revised by the
Author for America. In one handsome 12mo. volume of 784 pages,
with 88 illustrations. Cloth, $2.50, net.

It is replete with the latest inform- been adopted, bringing the work into

ation, and considers the chemistry of close touch with the latest United

every substance recognized officially States Pharmacopoeia, of which it is

or in general practice. The modern a worthy companion. — ThePittsburg

scientific chemical nomenclature has Medical Review.

BALLiENGER (W. L.) AND WIPPERN (A. G.). Shortly. A
POCKET TEXT-BOOK OF DISEASES OF THE EYE, EAR,
NOSE AND THROAT. In one handsome 12mo. volume of about
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Pocket Text-books, edited by BERN B. GALLAUDET, M. D. See p. 18.

BARNES (ROBERT AND FANCOURT). A SYSTEM OF OB-
STETRIC MEDICINE AND SURGERY. Octayo. 372 pages, with
CJoth, $5;

4 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

BACON (GORHAM). ON THE EAR. One 12mo. volume, 400 pages,
109 engravings and a colored plate. Cloth, net, $2.00. Just ready.

It is the best manual upon otology, dents of medicine — Cleveland Jour-
An intensely practical book for stu- nal of Medicine.

BARTHOLOW (ROBERTS). CHOLERA; ITS CAUSATION, PRE-
VENTION AND TREATMENT. In one 12mo. volume of 127 pages,
with 9 illustrations. Cloth, $1.25.

BARTHOLOW (ROBERTS). MEDICAL ELECTRICITY. A
PRACTICAL TREATISE ON THE APPLICATIONS OF ELEC-
TRICITY TO MEDICINE AND SURGERY. Third edition. In
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BELLi (F. JEFFREY). COMPARATIVE ANATOMY AND PHYS-
IOLOGY. In one 12mo. volume of 561 pages, with 229 engravings.
Cloth, $2. See Students' Series of Manuals, page 27.

BILLINGS (JOHN S.). THE NATIONAL MEDICAL DICTIONARY.
Including in one alphabet English, French, German, Italian and
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In two very handsome imperial octavo volumes containing 1574
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naif Morocco, $8.50. For sale by subscription only. Specimen pages
on application to the publishers.

BLACK (D. CAMPBELL). THE URINE IN HEALTH AND
DISEASE, AND URINARY ANALYSIS, PHYSIOLOGICALLY
AND PATHOLOGICALLY CONSIDERED. In one 12mo. volume
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Concise, practical, clinical, well
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A concise, yet complete manual,
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tical and clinical standpoint. — The
Ohio Medical Journal.

BLOXAM (C. L.). CHEMISTRY, INORGANIC AND ORGANIC.
With Experiments. New American from the fifth London edition.
In one handsome octavo volume of 727 pages, with 292 illustrations.
Cloth, $2 ; leather, $3.

BROCKWAY (F. J.). A POCKET TEXT-BOOK OF ANATOMY.
In one handsome 12mo. volume of about 400 pages, with many illus-
trations. Shortly. Cloth, $1.50, net. Lea's Series of Pocket Text-books,
edited by BERN B. GALLAUDET, M. D. See page 18.

BRUCE (J. MITCHELL). MATERIA MEDICA AND THERA-
PEUTICS. New (6th) edition. In one 12mo. volume of 600 pages.
Just ready. Cloth, $1.50, net. See Student's Series of Manuals,
page, 27.

PRINCIPLES OF TREATMENT. In one octavo volume. Pre-
paring.

BRYANT (THOMAS). THE PRACTICE OF SURGERY. Fourth
American from the fourth English edition. In one imperial octavo vol.
of 1040 pages, with 727 illustrations. Cloth, $6.50 ; leather, $7.50.

BURCHARD (HENRY H.). DENTAL PATHOLOGY AND THER-
APEUTICS. Handsome octavo, 575 pages, with 400 illustrations.
Just ready. Cloth, net, $5.00 ; leather, net, $6.00.

In the treatment of the subject
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js logical and sequential. The work

is a valuable text-book on a subject
which has heretofore not been ade-
quately rep resented. -Dental Cosmos,

LEA BROTHERS & Co., PHILADELPHIA AND NEW YOBK. 5

BURNETT (CHARLES H.). THE EAR : ITS ANATOMY, PHYSI-
OLOGY AND DISEASES. A Practical Treatise for the Use of
Students and Practitioners. Second edition. In one 8vo. volume of
580 pages, with 107 illustrations. Cloth, $4 ; leather, $5.

CARTER (R. BRUDENELL) AND FROST (W. ADAMS). OPH-
THALMIC SURGERY. In one pocket-size 12mo. volume of 559
pages, with 91 engravings and one plate. Cloth, $2.25. See Series of
Clinical Manuals, page 25.

CASPARI (CHARLES JR.). A TREATISE ON PHARMACY.
For Students and Pharmacists. In one handsome octavo volume of
680 pages, with 288 illustrations. Cloth, $4.50.

The author's duties as Professor student who cannot understand must

of Theory and Practice of Pharmacy be dull indeed. The book is full of

in the Maryland College of Phar- new, clean, sharp illustrations,which

macy, and his contact with students tell the story frequently at a glance,

made him aware of their exact The index is full and accurate. —

wants in the matter of a manual. National Druggist.
His work is admirable, and the 1

CHAPMAN (HENRY C.). A TREATISE ON HUMAN PHYSI-
OLOGY. New (2d) edition. In one octavo volume of 921 pages,
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In every respect the work fulfils
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mirable work of reference for the
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CHARLES (T. CRANSTOUN). THE ELEMENTS OF PHYSIO-
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CHEYNE (W. WATSON). THE TREATMENT OF WOUNDS,
. ULCERS AND ABSCESSES. In one 12nio. volume of 207 pages.
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One will be surprised at the
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need at any moment. The sections
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CHEYXE (W. W.) AND BURGH ARD (F. F.) SURGICAL
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CLARKE (W. B.) AND LOCKWOOD (C. B.). THE DISSECTOR'S
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CLELAND (JOHN). A DIRECTORY FOR THE DISSECTION OF
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CLINICAL MANUALS. See Series of Clinical Manuals, page 25.

CLOUSTON (THOMAS S.). CLINICAL LECTURES ON MENTAL
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6 LEA BBOTHEBS & Co., PHILADELPHIA AND NEW. YORK.

CLOWES (FRANK). AN ELEMENTARY TREATISE ON PRACTI-
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COAKLEY (CORNELIUS G.). THE DIAGNOSIS AND TREAT-
MENT OF DISEASES OF THE NOSE, THROAT, NASO-
PHARYNX AND TRACHEA. In one 12mo. volume of about 400
pages, fully illustrated. Preparing,

COATES (W. E., JR.). A POCKET TEXT-BOOK OF BACTE-
RIOLOGY AND HYGIENE. In one handsome 12mo. volume of
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Lea's Series of Pocket Text-books, edited by BERN B. GALLAUDET,
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COATS (JOSEPH). A TREATISE ON PATHOLOGY. In one vol.
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COLEMAN (ALFRED). A MANUAL OF DENTAL SURGERY
AND PATHOLOGY. With Notes and Additions to adapt it to Amer-
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handsome octavo vol. of 412 pages, with 331 engravings. Cloth, $3.25.

COLLINS (C. P.). A POCKET TEXT-BOOK OF MEDICAL
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COLLINS (H. D.) AND ROCKWELL (W. H.). A POCKET
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Lea's Series of Pocket Text-books, edited by BEEN B. GALLAUDET,
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CONDIE (D. FRANCIS). A PRACTICAL TREATISE ON THE DIS-
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CORNIL (V.). SYPHILIS: ITS MORBID ANATOMY, DIAGNO-
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J. HENEY C. SIMES, M.D. and J. WILLIAM WHITE, M. D. In one
8vo. volume of 461 pages, with 84 illustrations. Cloth, $3.75.

CROCKETT (M. A.). A POCKET TEXT-BOOK OF DISEASES
OF WOMEN. In one handsome 12mo. volume of about 350 pages,
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CROOK (JAMES K.) ON MINERAL WATERS OF THE
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CULBRETH (DAVID M. R.). MATERIA MEDICA AND PHAR-
MACOLOGY. In one handsome octavo volume of 812 pages, with
445 illustrations. Cloth, $4.75.

adopted as the text-book in all col-
leges of pharmacy and medicine.
It is one of the most valuable works

A thorough, authoritative and
systematic exposition of its most
important domain. — The Canada
Lancet.

This work ought to be at once

that have been issued. — The Ohi
Medical Journal.

CUSHNY (ARTHUR R.). TEXT-BOOK OF PHARMACOLOGY.

Handsome 8vo., 728 pages, with 47 illus. Just ready. Cloth, $3.75, net.

LEA BBOTHKBS & Co., PHILADELPHIA AND NEW YOEK. 7

DAI/TON (JOHN C.). A TKEATISE ON HUMAN PHYSIOLOGY.

Seventh edition. Octavo, 722 pages, with 252 engravings. Cloth,
$5 ; leather, $6.

DOCTRINES OF THE CIRCULATION OF THE BLOOD. In

one handsome 12mo. volume of 293 pages. Cloth, $2.

DAVENPORT (F. H.). DISEASES OF WOMEN. A Manual of
Gynecolpgy. For the use of Students and Practitioners. New
(3d) edition. In one handsome 12mo. volume of 387 pages, with 150
illustrations. Cloth, $1.75, net. Just ready.

DAVIS (EDWARD P.). A TREATISE ON OBSTETRICS. FOB
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plates in colors and monochrome. Cloth, $5 ; leather, $6.

This work must become the prac-
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A work unequalled in excellence.
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Decidedlv one of the best text-

books on the subject. It is exception-
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From a practical standpoint the
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DAVIS (P. H.). LECTURES ON CLINICAL MEDICINE. Second
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DE LA HECHE'S GEOLOGICAL OBSERVER. In one large octavo
volume of 700 pages, with 300 engravings. Cloth, $4.

DENNIS (FREDERIC S.) AND BHJLINGS (JOHN S.). A SYS-
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Complete work in four very handsome octavo volumes, containing
3652 pages, with 1585 engravings and 45 full-page plates in colors
and monochrome. Per volume, cloth, $6.00; leather, $7.00; half
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Full prospectus free on application to the publishers.

It is worthy of the pogition which ; American surgery and is thoroughly
surgery has attained in the great ! practical. — Annals of Surgery.
Republic whence it comes. — The ' No work in English can be con-
London Lancet. sidered as the rival of this. — The

It may be fairly said to represent American Journal of the Medical
the most advanced condition of; Sciences.

DERCUM (FRANCIS X., EDITOR). A TEXT-BOOK ON
NERVOUS DISEASES. By American Authors. In one handsome
octavo volume of 1054 pages, with 341 engravings and 7 colored
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Representing the actual status of The work is representative of the

our knowledge of its subjects, and best methods of teaching, as devel-

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of any of its class. — Jour, of Amer- of this country. — Alienist and Neu-

ican Med. Association. rologist.

The most thoroughly up-to-date The best text-book in any Ian-
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— American Journal of Insanity.

DE SCHWEINITZ (GEORGE E.). THE TOXIC AMBLYOPIAS.
Their Classification, History, Symptoms, Pathology and Treatment.
Very handsome octavo, 240 pages, 46 engravings, and 9 full-page
plates in colors. Limited edition, de luxe binding, $4. Net.

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DRAPER (JOHN C.). MEDICAL PHYSICS. A Text-book for Stu-
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DRUITT (ROBERT). THE PRINCIPLES AND PRACTICE OF
MODERN SURGERY. A new American, from the twelfth London
edition, edited by STANLEY BOYD, F. R. C. S. In one large octavo
volume of 965 pages, with 373 engravings. Cloth, $4 ; leather, $5.
DUANE (ALEXANDER). THE STUDENT'S DICTIONARY OF
MEDICINE AND THE ALLIED SCIENCES. New edition. Com-
prising the Pronunciation, Derivation and Full Explanation of Medi-
cal Terms, with much Collateral Descriptive Matter. Numerous Tables,
etc. Square octavo of 658 pages. Cloth, $3.00; half leather, $3.25;
full sheep, $3.75. Thumb-letter Index, 50 cents extra.

convenience and thoroughness. —
Medical Record.

The best student's dictionary. —
Canada Lancet.

Far superior to any dictionary for
the medical student that we know of.
— Western Med. and Surg. Reporter.

The book is brought accurately to

date. It is a model of conciseness,

DUDLEY (E. C.). THE PRINCIPLES AND PRACTICE OF
GYNECOLOGY. Handsome octavo of 652 pages, with 422 illustra-
tions in black and colors. Cloth, $5.00, net ; leather, $6.00, net. Just
ready.

The book can be safely recom-
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tice of modern gynecology. — Inter-
national Medical Magazine.

exposition of the principles and prac-

DUNCAN (J. MATTHEWS). CLINICAL LECTURES ON THE
DISEASES OF WOMEN. Delivered in St. Bartholomew's Hospital.
In one octavo volume of 175 pages. Cloth, $1.50.

DTJNGLJSON (ROBLJEY). A DICTIONARY OF MEDICAL SCI-
ENCE. Containing a full explanation of the various subjects and
terms of Anatomy, Physiology, Medical Chemistry, Pharmacy, Phar-
macology, Therapeutics, Medicine, Hygiene, Dietetics, Pathology, Sur-
gery, Ophthalmology, Otology, Laryngology, Dermatology, Gynecol-
ogy, Obstetrics, Pediatrics, Medical Jurisprudence, Dentistry, etc., etc.
Bv ROBLEY DUNGLISON, M. D., LL. D., late Professor of Institutes
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In one magnificent imperial octavo volume of 1225 pages. Cloth, $7 ;
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The most satisfactory and authori-
tative guide to the derivation, defini-
tion and pronunciation of medical
terms. — The CharlotteMed. Journal.

Covering the entire field of medi-
cine, surgery and the collateral

scarcely be measured. — Med. Record.
Pronunciation is indicated by the
phonetic system. The definitions are
unusually clear and concise. The
book is wholly satisfactory.— Uni-
versity Medical Magazine.

sciences, its range of usefulness can

DUNHAM (EDWARD K.). MORBID AND NORMAL HIS-
TOLOGY. Octavo, 450 pages,with 363 illustrations. Cloth, $3.25, net.
Just ready.
The best one- volume text or refer- 1 of published in America. — Virginia

ence book on histology that we know I Medical Semi-Monthly.

EDES (ROBERT T.). TEXT-BOOK OF THERAPEUTICS AND
MATERIA MEDICA. In one 8vo. volume of 544 pages. Cloth, $3.50 ;
leather, $4.50.

EDIS (ARTHUR W.). DISEASES OF WOMEN. A Manual for
Students and Practitioners. In one handsome 8vo. volume of 576 pages,
with 148 engravings. Cloth, $3 ; leather, $4.

LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK. 9

EGBERT (SENECA). A MANUAL OF HYGIENE AND SANI-
TATION. In one 12mo. volume of 359 pages, with 63 illustrations.
Just ready. Cloth, Net, $2.25.

It is written in plain language,
and, while primarily designed for

ligence. The writer has adapted it
to American conditions, and his

physicians, it can be studied with suggestions are, above all, practical,
profit by any one of ordinary intel- | — The NeivYork Medical Journal.

ELLIS (GEORGE VINER). DEMONSTRATIONS IN ANATOMY.
Eighth edition. Octavo, 716 pages, with 249 engravings. Cloth,
$4.25 ; leather, $5.25.

EMMET (THOMAS ADDIS). THE PRINCIPLES AND PRAC-
TICE OF GYNAECOLOGY. Third edition. Octavo, 880 pages, with
150 original engravings. Cloth, $5 ; leather, $6.

ERICHSEN (JOHN E.). THE SCIENCE AND ART OF SUR-
GERY. Eighth edition. In two large octavo volumes containing
2316 pages, with 984 engravings. Cloth, $9 ; leather, $11.

ESSIG (CHARLES J.). PROSTHETIC DENTISTRY. See American
Text-Books of Dentistry, page 2.

EVANS (DAVID J.). A POCKET TEXT-BOOK OF OBSTETRICS.
In one handsome 12mo. volume of about 300 pages, with many illustra-
tions. Cloth, $1.50, net. Shortly. Lea's Series of Pocket Text-books,
edited by BERN B. GALLATJDET, M. D. See page 18.

FARQUHARSON (ROBERT). A GUIDE TO THERAPEUTICS.
Fourth American from fourth English edition, revised by FRANK
WOODBURY, M. D. In one 12mo. volume of 581 pages. Cloth, $2.50.

FIELD (GEORGE P.). A MANUAL OF DISEASES OF THE
EAR. Fourth edition. In one octavo volume of 391 pages, with 73
engravings and 21 colored plates. Cloth, $3.75.

To those who desire a concise j It is just such a work as is needed
work on diseases of the ear, clear I by every general practitioner. —
and practical, this manual com- American Practitioner and News.
mends itself in the highest degree. '

FLINT (AUSTIN). A TREATISE ON THE PRINCIPLES AND
PRACTICE OF MEDICINE. Seventh edition, thoroughly revised
by FREDERICK P. HENRY, M. D. In one large 8vo. volume of 1143
pages, with engravings. Cloth, $5.00 ; leather, $6.00.

The work has well earned its lead- i medicine in the medical schools. —
ing place in medical literature. — Northwestern Lancet.
Medical Record. The best of American text-books

The leading text-book on general

A MANUAL OF AUSCULTATION AND PERCUSSION; of

the Physical Diagnosis of Diseases of the Lungs and Heart, and of
Thoracic Aneurism. Fifth edition, revised by JAMES C. WILSON, M. D.
In one handsome 12mo. volume of 274 pages, with 12 engravings.

A PRACTICAL TREATISE ON THE DIAGNOSIS AND

TREATMENT OF DISEASES OF THE HEART. Second edition
enlarged. In one octavo volume of 550 pages. Cloth, $4.

A PRACTICAL TREATISE ON THE PHYSICAL EXPLO-
RATION OF THE CHEST, AND THE DIAGNOSIS OF DIS-
EASES AFFECTING THE RESPIRATORY ORGANS. Second
and revised edition. In one octavo volume of 591 pages. Cloth, $4.50.

MEDICAL ESSAYS. In one 12mo. vol. of 210 pages. Cloth, $1.38.

ON PHTHISIS : ITS MORBID ANATOMY ETIOLOGY, ETC.

A Series of Clinical Lectures. In one 8vo. volume of 442 pages.
Cloth, $3.50.

10 LEA BEOTHEES & Co., PHILADELPHIA AND NEW YORK.

FOLSOM (C. P.). AN ABSTRACT OF STATUTES OF U. S.
ON CUSTODY OF THE INSANE. In one 8vo. vol. of 108 pages.
Cloth, $1.50. With Clouston on Mental Diseases (new edition, see
page 6) $5.00, net, for the two works.

FORMULARY, POCKET, see page 32.

FOSTER (MICHAEL). A TEXT-BOOK OF PHYSIOLOGY. New

(6th) and revised American from the sixth English edition. In one
large octavo volume of 923 pages, with 257 illustrations. Cloth, $4.50 ;
leather, $5.50.

Unquestionably the best book that j This single volume contains all
can be placed in the student's hands, i that will be necessary in a college
and as a work of reference for the j course, and all that the physician
busy physician it can scarcely be will need as well.— Dominion Med.
excelled.— ThePhila. Poly clinic. \ Monthly.

FOTHERGILL (J. MILNER). THE PRACTITIONER'S HAND-
BOOK OF TREATMENT. Third edition. In one handsome octavo
volume of 664 pages. Cloth, $3.75 ; leather, $4.75.

To have a description of the
normal physiological processes of an
organ and of the methods of treat-
ment of its morbid conditions
brought together in a single chapter,
and the relations between the two

clearly stated, cannot fail to prove
a great convenience to many thought-
ful but busy physicians. The prac-
tical value of the volume is greatly
increased by the introduction of many
prescriptions — New York Med. Jour.

FOWNES (GEORGE). A MANUAL OF ELEMENTARY CHEM-
ISTRY (INORGANIC AND ORGANIC). Twelfth edition. Em-
bodying WATTS' Physical and Inorganic Chemistry. In one royal
12mo. volume of 1061 pages, with 168 engravings, and 1 colored
plate. Cloth, $2.75 ; leather, $3.25.

FRANKLAND (E.) AND JAPP (F.R.). INORGANIC CHEMISTRY.

In one handsome octavo volume of 677 pages, with 51 engravings and
2 plates. Cloth, $3.75 ; leather, $4.75.

FULLER (EUGENE). DISORDERS OF THE SEXUAL OR-
GANS IN THE MALE. In one very handsome octavo volume of
238 pages, with 25 engravings and 8 full-page plates. Cloth, $2.

It is an interesting work, and one
which, in view of the large and
profitable amount of work done in
this field of late years, is timely and
well needed. — Medical Fortnightly.

tive and brings views of sound
pathology and rational treatment to
many cases of sexual disturbance
whose treatment has been too often
fruitless for good. — Annals of

The book is valuable and instruc- Surgery.

FULLER (HENRY). ON DISEASES OF THE LUNGS AND AIR
PASSAGES. Their Pathology, Physical Diagnosis, Symptoms and
Treatment. From second English edition. In one 8vo. volume of 475
pages. Cloth, $3.50.

GALLAUDET (BERN B.). A POCKET TEXT-BOOK ON SUR-
GERY. In one handsome 12mo. volume of about 400 pages, with many
illustrations. Cloth, $1.50, net. Shortly. Lea's Series of Pocket Text-
booh; edited by BERN B. GALLAUDET, M. D. See page 18.

GANT (FREDERICK JAMES). THE STUDENT'S SURGERY. A
Multum in Parvo. In one square octavo volume of 845 pages, with
159 engravings. Cloth, $3.75.

GLBBES (HENEAGE). PRACTICAL PATHOLOGY AND MORBID
HISTOLOGY. Octavo, 314 pages, with 60 illustrations. Cloth, $2.75.

G1BNEY (V. P.). ORTHOPEDIC SURGERY. For the use of Practi-
tioners and Students. In one 8vo. vol. profusely illus. Preparing.

LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK. 11

GERRISH (FREDERIC H.). A TEXT-BOOK OF ANATOMY.
By American Authors. Edited by Frederic H. Gerrish, M. D. In one
imp. octavo volume of 915 pages, with 950 illustrations in black and
colors. Just ready. Clth,$6.50; flexible waterproof, $7; leath., $7.50, net.

In this, the first representative treatise on Anatomy produced in America,
no effort or expense has been spared to unite an authoritative text with the
most successful anatomical pictures which have yet appeared in the world.

The editor has secured the co-operation of the professors of anatomy in
leading medical colleges, and with them ha8 prepared a text conspicuous
for its simplicity, unity and judicious selection of such anatomical facts as
bear on physiology, surgery and internal medicine in the most compre-
hensive sense of those terms. The authors have endeavored to make a
book which shall stand in the place of a living teacher to the student, and
which shall be of actual service to the practitioner in his clinical work,
emphasizing the most important subjects, clarifying obscurities, helping
most in the parts most difficult to learn, and illustrating everything by all
available methods.

GOULD (A. PEARCE). SUKGICAL DIAGNOSIS. In one 12mo.

vol. of 589 pages. Cloth, $2. See Student's Series of Manuals, p. 27.

GRAY (HENRY). ANATOMY, DESCRIPTIVE AND SURGICAL.

New and thoroughly revised American edition, much enlarged in text,
and in engravings in black and colors. In one imperial octavo volume
of 1239 pages, with 772 large and elaborate engravings on wood. Price
of edition with illustrations in colors : cloth, $7 ; leather, $8. Price
of edition with illustrations in black : cloth, $6 ; leather, $7.

This is the best single volume
upon Anatomy in the English
language. — University Medical Mag-
azine.

Gray's Anatomy affords the student
more satisfaction than any other
treatise with which we are familiar.
— Buffalo Med. Journal.

The most largely used anatomical
text-book published in the English
language. — Annals of Surgery.

Particular stress is laid upon the
practical side of anatomical teach-

ing, and especially the Surgical
Anatomy. — Chicago Med. Recorder.

Holds first place in the esteem of
both teachers and students. — The
Brooklyn Medical Journal.

The foremost of all medical text-
books.— Medical Fortnightly.

Gray's Anatomy should be the
first work which a medical student
should purchase, nor should he be
without a copy throughout his pro-
fessional career. — Pittsburg Medical
Review.

GRAY (LANDON CARTER). A TREATISE ON NERVOUS AND
MENTAL DISEASES. For Students and Practitioners of Medicine.
New (2d) edition. In one handsome octavo volume of 728 pages, with
172 engravings and 3 colored plates. Cloth, $4.75; leather, $5.75.
An up-to-date text-book upon measures which are often the phy si-

nervous and mental diseases com-

bined,
plicit,

A well-written, terse, ex-
and authoritative volume

treating of both subjects is a step in
the direction of popular demand. —
The Chicago Clinical Review.

"The word treatment," says the
author, " has been construed in the
broadest sense to include not only
medicinal and non-medicinal agents,
but also those hygienic and dietetic

cian's best reliance." — The Journal
of the American Medical Association.
The descriptions of the various
diseases are accurate and the symp-
toms and differential diagnosis are
set before the student in such a way
as to be readily comprehended. The
author's long experience renders his
views on therapeutics of great value.
— The Journal of Nervous and Men-
tal Disease.

12 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

GREEN (T. HENRY). AN INTRODUCTION TO PATHOLOGY
AND MORBID ANATOMY. New (8th) American from the eighth
London edition. In one handsome octavo volume of 582 pages, with
216 engravings and a colored plate. Cloth, $2.50, net. Just ready.

A work that is the text-book of

Srobably four-fifths of all the stu-
ents of pathology in the United
States and Great Britain stands in
no need of commendation. The work
precisely meets the needs and wishes
of the general practitioner. — The
American Practitioner and News.
Green's Pathology is the text-book

of the day — as much so almost as
Gray's Anatomy. It is fully up-to-
date in the record of fact, and so pro-
fusely illustrated as to give to eacli
detail of text sufficient explanation.
The work is an essential to the prac-
titioner— whether as surgeon or phys-
ician. It is the best of up-to date
text-books. — VirginiaMed. Monthly.

GREENE (WILLIAM H.). A MANUAL OF MEDICAL CHEM-
ISTRY. For the Use of Students. Based upon BOWMAN'S Medical
Chemistry. In one 12mo. vol. of 310 pages, with 74 illus. Cloth, $1.75.

GROSS (SAMUEL, D.)- A PRACTICAL TREATISE ON THE DIS-
EASES, INJURIES AND MALFORMATIONS OF THE URINARY
BLADDER, THE PROSTATE GLAND AND THE URETHRA.
Third edition. Octavo, 574 pages, with 170 illustrations Cloth, $4.50.

GRINDON (JOSEPH). A POCKET TEXT-BOOK OF SKIN
DISEASES. In one handsome 12mo. volume of 350 pages, with
many illustrations. Shortly. Cloth, $1.50, net. Lea?* Series of Pocket
Text-looks, edited by BERN B. GALLAUDET, M. D. See page 18.

HABERSHON (S. O.). ON THE DISEASES OF THE ABDOMEN
Second American from the third English edition. In one octavo vol-
ume of 554 pages, with 11 engravings. Cloth, $3.50.

HALL, (WINFIELD S.) TEXT-BOOK OF PHYSIOLOGY. Octavo
about 500 pages, richly illustrated. In press.

HAMILTON (ALLAN MCLANE). NERVOUS DISEASES. THEIR
DESCRIPTION AND TREATMENT. Second and revised edition.
In one octavo volume of 598 pages, with 72 engravings. Cloth, $4.

HARD A WAY (W. A.). MANUAL OF SKIN DISEASES. New (2d)
edition. In one 12mo. volume of 560 pages, with 40 illustrations and
2 plates. Cloth, $2.25, net. Just ready.
The best of all the small books to I day clinical experience. His great

recommend to students and practi-
tioners. Probably no one of our
dermatologists has had a wider every-

strength is in diagnosis, descriptions
of lesions and especially in treat-
ment.— Indiana Medical Journal.

HARE (HOBART AMORY). PRACTICAL DIAGNOSIS. THE
USE OF SYMPTOMS IN THE DIAGNOSIS OF DISEASE. New
(4th) edition. In one octavo volume of 623 pages, with 205 engravings
and 14 full-page colored plates. Cloth, $5.00, net. Just ready.

It is unique in many respects, and
the author has introduced radical
changes which will be welcomed by
all. Anyone who reads this book
will become a more acute observer,
will pay more attention to the simple
yet indicative signs of disease, and 1

he will become a better diagnosti-
cian. This is a companion to Prac-
tical Therapeutics, by the same
author, and it is difficult to conceive
of any two works of greater practical
utility. — Medical Review.

LEA BROTHERS & Co., PHILADELPHIA AND NEW YOBK. 13

HARE (HOBART AMORY). A TEXT-BOOK OF PRACTICAL
THERAPEUTICS, with Special Reference to the Application of Reme-
dial Measures to Disease and their Employment upon a Rational
Basis. With articles on various subjects by well-known specialists.
Xew (7th) and revised edition. In one octavo volume of 776 pages.
Cloth, $3.75, net; leather, $4.50, net.

Its classifications are inimitable, I it can be readily used in connection
and the readiness with which any- 1 with Hare's Practical Diagnosis.
thing can be found is the most won- 1 For the needs of the student and
derful achievement of the art of in- 1 general practitioner it has no equal,
dexing. This edition takes in all I — Medical Sentinel.
the latest discovered remedies. — The best planned therapeutic work

The St. Louis Clinique.

The great value of the work lies
in the fact that precise indications
for administration are given. A
complete index of diseases and
remedies makes it an easy reference
work. It has been arranged so that

of the century. — American Prac-
titioner and News.

It is a book precisely adapted to
the needs of the busy practitioner,
who can rely upon finding exactly
what he needs. — The National Med-
ical Review.

HARE (HOBART AMORY) ON THE MEDICAL COMPLICA
TIONS AND SEQUELJE OF TYPHOID FEVER. Octavo, 276
pages, 21 engravings and two full- page plates. Just ready. Cloth,
$2.40, net.

A very valuable production. One , read with great profit. — Cleveland
of the very best products of Dr. Journal of Medicine.
Hare and one that every man can >

HARE (HOBART AMORY, EDITOR). A SYSTEM OF PRAC-
TICAL THERAPEUTICS. In a series of contributions by eminent
practitioners. In four large octavo volumes comprising about 4500
pages,with about 550 engravings. Vol. IV., just ready. For sale by sub-
scription only. Full prospectus free on application to the Publishers.
Regular price, Vol. IV., cloth, $6 ; leather, $7 ; half Russia, $8.
Price Vol. IV. to former or new subscribers to complete work, cloth,
$5 ; leather, $6 ; half Russia, $7. Complete work, cloth, $20 ; leather,
$24 ; half Russia, $28.

The great value of Hare's System of Practical Therapeutics has led to a
widespread demand for a new volume to represent advances in treatment
made since the publication of the first three. More than fulfilling this
request the Editor has secured contributions from practically a new corps
of equally eminent authors, so that entirely fresh and original matter is
ensured. The plan of the work, which proved so successful, has been fol-
lowed in this new volume, which will be found to present the latest devel-
opments and applications of this most practical branch of the medical art.
The entire System is an unrivalled encyclopaedia on the practical parts of
medicine, and merits the great success it has won for that reason.

14 LEA BBOTHEES & Co., PHILADELPHIA AND NEW YORK.

HARTSHORNE (HENRY). ESSENTIALS OF THE PRINCIPLES
AND PRACTICE OF MEDICINE. Fifth edition. In one 12mo.
volume, 669 pages, with 144 engravings. Cloth, $2.75 .

— A HANDBOOK OF ANATOMY AND PHYSIOLOGY. In one
12mo. volume of 310 pages, with 220 engravings. Cloth, $1.75.

A CONSPECTUS OF THE MEDICAL SCIENCES. Comprising

Manuals of Anatomy, Physiology, Chemistry, Materia Medica, Prac-
tice of Medicine, Surgery and Obstetrics. Second edition. In one royal
12mo. vol. of 1028 pages, with 477 illus. Cloth, $4.25 ; leather, $5.

HAYDEN (JAMES R.). A MANUAL OF VENEREAL DISEASES.

New (2d) edition. In one 12mo. volume of 304 pages, with 54 en-
gravings. Cloth, $1.50, net. Just ready.

It is practical, concise, definite
and of sufficient fulness to be satis-
factory.— Chicago Clinical Review.

This work gives all of the prac-
tically essential information about
the three venereal diseases, gon-
orrhoea, the chancroid and syphilis.
In diagnosis and treatment it is par-

ticularly thorough, and may be
relied upon as a guide in the man-
agement of this class of diseases. —
Northwestern Lancet.

It is well written, up to date, and
will be found very useful. — Inter-
national Medical Magazine.

HAYEM (GEORGES) AND HARE (H. A.). PHYSICAL AND
NATURAL THERAPEUTICS. The Remedial Use of Heat, Elec-
tricity, Modifications of Atmospheric Pressure, Climates and Mineral
Waters. Edited by Prof. H. A. HARE, M. D. In one octavo volume
of 414 pages, with 113 engravings. Cloth, $3.

This well-timed up-to-date volume
is particularly adapted to the re-
quirements of the general practi-
tioner. The section on mineral
waters is most scientific and prac-
tical. Some 200 pages are given up
to electricity and evidently embody
the latest scientific information on
the subject. Altogether this work
is the clearest and most practical aid
to the study of nature's therapeutics
that has yet come under our obser-
vation.— The Medical Fortnightly.

For many diseases the most potent
remedies lie outside of the materia
medica, a fact yearly receiving wider

recognition. Within this large
range of applicability, physical
agencies when compared with drugs
are more direct and simple in their
results. Medical literature has long
been rich in treatises upon medical
agents, but an authoritative work
upon the other great branch of
therapeutics has until now been a
desideratum. The section on climate,
rewritten by Prof. Hare, will, for
the first time, place the abundant
resources of our country at the in-
telligent command of American
practitioners. — The Kansas City
Medical Index.

HERMAN (G. ERNEST). FIRST LINES IN MIDWIFERY.

one 12mo. vol. of 198 pages, with 80 engravings. Cloth, $1.25.
Student's Series of Manuals, page 27.

HERMANN (L.). EXPERIMENTAL PHARMACOLOGY. A Hand-
book of the Methods for Determining the Physiological Actions of
Drugs. Translated by ROBERT MEADE SMITH, M. D. In one J2mo,
volume of 199 pages, with 33 engravings, Cloth, $J,5Q,

LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK. 15

HERRICK (JAMES B.). A HANDBOOK OF DIAGNOSIS. In
one handsome 12mo. volume of 429 pages, with 80 engravings and 2
colored plates. Cloth, $2.50.

Excellently arranged, practical,
concise, up-to-date, and eminently
well fitted lor the use of the prac-
titioner as well as of the student—
Chicago Med. Recorder.

This volume accomplishes its ob-
jects more thoroughly and com-
pletely than any similar work yet
published. Each section devoted" to
diseases of special systems is pre-
ceded with an exposition of the
methods of physical, chemical and

microscopical examination to be em-
ployed in each class. The technique
of blood examination,including color
analysis, is very clearly stated.
Uranalysis receives adequate space
and care. — New York Med. Journal.
We commend the book not only to
the undergraduate, but also to the
physician who desires a ready means
of refreshing his knowledge of diag-
nosis in the exigencies of professional
life. — Memphis Medical Monthly.

HILJj (BERKELEY). SYPHILIS AND LOCAL CONTAGIOUS
DISORDERS. In one 8vo. volume of 479 pages. Cloth, $3.25.

HLLLIER (THOMAS). A HANDBOOK OF SKIN DISEASES.
Second edition. In one royal 12mo. volume of 353 pages, with two
plates. Cloth, $2.25.

HIRST (BARTON C.) AND PD3RSOL (GEORGE A.). HUMAN

MONSTROSITIES. Magnificent folio, containing 220 pages of text
and illustrated with 123 engravings and 39 large photographic plates
from nature. In four parts, price each, $5. Limited edition. For sale
by subscription only.

HOBLYN (RICHARD D.). A DICTIONARY OF THE TERMS
USED IN MEDICINE AND THE COLLATERAL SCIENCES.
In one 12mo. volume of 520 double-columned pages. Cloth, $1.50 ;
leather, $2.

HODGE (HUGH Li.). ON DISEASES PECULIAR TO WOMEN.
INCLUDING DISPLACEMENTS OF THE UTERUS. Second and
revised edition. In one 8vo. vol. of 519 pp., with illus. Cloth, $4.50.

HOFFMANN (FREDERICK) AND POWER (FREDERICK B.).

A MANUAL OF CHEMICAL ANALYSIS, as Applied to the
Examination of Medicinal Chemicals and their Preparations. Third
edition, entirely rewritten and much enlarged. In one handsome octavo
volume of 621 pages, with 179 engravings. Cloth, $4.25.

HOLMES (TIMOTHY). A TREATISE ON SURGERY. Its Prin-
ciples and Practice. A new American from the fifth English edition.
Edited by T. PICKERING PICK, F.R.C.S. In one handsome octavo vol-
ume of 1008 pages, with 428 engravings. Cloth, $6 ; leather, $7.

— A SYSTEM OF SURGERY. With notes and additions by various
American authors. Edited by JOHN H. PACKARD, M. D. In three
very handsome 8vo. volumes containing 3137 double-columned pages,
with 979 engravings and 13 lithographic plates. Per volume, cloth, $6 ;
leather, $7 ; fcalf Russia, $7.5Q, For tv4t by tubwriptivn only.

16 LEA BROTHEBS & Co., PHILADELPHIA AND NEW YORK.

HORNER (WILLIAM E.). SPECIAL ANATOMY AND HIS-
TOLOGY. Eighth edition, revised and modified. In two large 8vo.
volumes of 1007 pages, containing 320 engravings. Cloth, $6.

HUDSON (A.). LECTURES ON THE STUDY OF FEVER. In one
octavo volume of 308 pages. Cloth, $2.50.

HUTCHISON (ROBERT) AND RAINY (HARRY). CLINICAL
METHODS. A GUIDE TO THE PRACTICAL STUDY OF
MEDICINE. In one 12mo. volume of 562 pages, with 137 engrav-
ings and 8 colored plates. Cloth, $3.00.

A comprehensive, clear and re-
markably up-to-date guide to clinical
diagnosis. The illustrations are
plentiful and excellent. As exam-
ples of the more recent additions to

medical knowledge which receive
recognition, we mention Widal's
test for typhoid and the Neuron
theory of the nervous system. —
Montreal Medical Journal.

HUTCHINSON (JONATHAN). SYPHILIS. In one pocket-size 12mo.
volume of 542 pages, with 8 chromo-lithographic plates. Cloth, $2.25.
See Series of Clinical Manuals, p. 25.

HYDE (JAMES NEVINS). A PRACTICAL TREATISE ON DIS-
EASES OF THE SKIN. New (4th) edition, thoroughly revised.
In one octavo volume of 815 pages, with 110 engravings and 12 full-
page plates, 4 of which are colored. Cloth, $5.25 ; leather, $6.25.

This edition has been carefully re-
vised, and every real advance has
been recog n i zed . Theworkanswers
the needs of the general practitioner,
the specialist, and the student.— The
Ohio Med. Jour.

A treatise of exceptional merit
characterized by conscientious care
and scientific accuracy. — Buffalo
Med. Journal.

A complete exposition of our
knowledge of cutaneous medicine as
it exists to-day. The teaching in-
culcated throughout is sound as well

as practical. — The American Jour-
nal of the Medical Sciences.

It is the best one-volume work
that we know. The student who
gets this book will find it a useful
investment, as it will well serve him
when he goes into practice. — Vir-
ginia Medical Semi-Monthly.

A full and thoroughly modern
text-book on dermatology. — The
Pittsburg Medical Review.

It is the most practical hand-
book on dermatology with which we
are acquainted. — The Chicago Med-
ical Recorder.

JACKSON (GEORGE THOMAS). THE READY-REFERENCE
HANDBOOK OF DISEASES OF THE SKIN. New (3d) edition.
In one 12mo. volume of 637 pages, with 75 illustrations and a colored
plate. Just ready. Cloth, $2.50, net.

As a student's manual, it may be
considered beyond criticism. The
book is singularly full.— St. Louis
Medical and Surgical Journal.

Without doubt forms one of the
best guides for the beginner in der-
matology that is to be found in the
English language. — Medicine.

JAMIESON,(W. AJLL.AN). DISEASES OF THE SKIN. Third
edition. In one octavo volume of 656 pages, with 1 engraving and 9
double-page chromo-lithographic plates, Cloth, $6,

LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK. 17

JEWETT (CHARLES). ESSENTIALS OF OBSTETRICS. In one
12mo. volume of 356 pages, with 80 engravings and 3 colored plates.
Cloth, $2.25. Just ready.
An exceedingly useful manual for j ing it in attractive and easily tangi-

student and practitioner. The au- j ble form. The book is well illus-

thor has succeeded unusually well j trated throughout. — Nashville Jour.

in condensing the text and in arrang- 1 of Medicine and Surgery.

THE PRACTICE OF OBSTETRICS. By American Authors.

One large octavo volume of 763 pages, with 441 engravings in black
and colors, and 22 full-page colored plates. Just ready. Cloth,
$5.00, net ; leather, $6.00, net.

A clear and practical treatise upon I the book abounds. The work is
obstetrics by well-known teachers of i sure to be popular with medical
the subject. A special feature of ! students, as well as being of extreme
this work would seem to be the i value to the practitioner. — The
excellent illustrations with which | Medical Age.

JONES (C. HANDF1ELD). CLINICAL OBSERVATIONS ON
FUNCTIONAL NERVOUS DISORDERS. Second American edi-
tion. In one octavo volume of 340 pages. Cloth, $3.25.

JUL.ER (HENRY). A HANDBOOK OF OPHTHALMIC SCIENCE
AND PRACTICE. Second edition. In one octavo volume of 549
pages, with 201 engravings, 17 chromo-lithographic plates, test-types of
Jaeger and Snellen, and Holmgren's Color-Blindness Test. Cloth,
$5.50; leather, $6.50.

The volume is particularly rich in | color blindness, etc. The sections
matter of practical value, such as ' devoted to treatment are singularly
directions for diagnosing, use of full and concise. — Medical Age.
instruments, testing for glasses, for |

KING (A. F. A.). A MANUAL OF OBSTETRICS. Seventh edition.
In one 12mo. volume of 573 pages, with 223 illustrations. Cloth,
$2.50.

From first to finish it is thoroughly cyclopedias. The well-arranged
practical, concise in expression, well index renders the book useful to
illustrated, and includes a statement ! the practitioner who is in haste to
of nearly every fact of importance refresh his memory. — Virginia
discussed in obstetric treatises or | Medical Semi-Monthly.

KIRK (EDWARD C.). OPERATIVE DENTISTRY. Handsome
octavo of 700 pages, with 751 illustrations. Just ready. See American
Text- Books of Dentistry, page 2.

We have only the highest praise tempted. We can heartily recom-
for this valuable work. It is replete ; mend it to the profession. — The
in every particular, and surpasses Ohio Dental Journal.
anything of the kind heretofore at- )

KLEIN (E.). ELEMENTS OF HISTOLOGY. New (5th) edition. In
one 12mo. volume of 506 pages, with 296 engravings. Just ready.
Cloth, $2.00, net. See Student's Series of Manuals, page 27.

It is the most complete and con- This work deservedly occupies a
cise work of the kind that has yet first place as a text-book on his-
emanated from the press. — ThcMed- \ tology. — Canadian Practitioner,
ical Age.

18 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

LANDIS (HENRY G.). THE MANAGEMENT OF LABOR. In one

handsome 12mo. volume of 329 pages, with 28 illus. Cloth, $1.75.

LA ROCHE (R.). YELLOW FEVER. In two 8vo. volumes of 1468
pages. Cloth, $7.

LAURENCE (J. Z.) AND MOON (ROBERT C.). A HANDY-
BOOK OF OPHTHALMIC SURGERY. Second edition. In one
octavo volume of 227 pages, with 66 engravings. Cloth, $2.75.

LEA'S SERIES OF POCKET TEXT-BOOKS, edited by BERN
B. GALLATJDET, M. D. Covering the entire field of Medicine in a
series of 16 very handsome cloth-bound 12mo. volumes of 350-450
pages each, profusely illustrated. Compendious, clear, trustworthy and
modern, and issued at the very moderate price of $1.50, net, per
volume. The following volumes constitute the series.

COATES' Bacteriology and Hygiene. BROCKWAY'S Anatomy. COLLINS
and ROCKWELL'S Physiology. MARTIN and ROCKWELL'S Chemistry
and Physics. NICHOLS and VALE'S Histology and Pathology.
SCHLEIF'S Materia Medica, Therapeutics, Medical Latin, etc. MALS-
BARY'S Practice of Medicine. COLLINS' Diagnosis. POTTS' Nervous
and Mental Diseases. GALLAUDET'S Surgery. LIKES' Genito-
Urinary and Venereal Diseases. GRINDON'S Dermatology. BALLEN-
GER and WIPPERN'S Diseases of the Eye, Ear, Throat and Nose.
EVANS' Obstetrics. CROCKETT'S Gynecology. TUTTLE'S Diseases of
Children.

For separate notices see under various authors' names.

LEA (HENRY C.). A HISTORY OF AURICULAR CONFESSION
AND INDULGENCES IN THE LATIN CHURCH. In three
octavo volumes of about 500 pages each. Per volume, cloth, $3.00.

CHAPTERS FROM THE RELIGIOUS HISTORY OF SPAIN;

CENSORSHIP OF THE PRESS; MYSTICS AND ILLUMINATI-
THE ENDEMONIADAS; EL SANTO NINO DE LA GUARDIA;
BRIANDA DE BARDAXI. 12mo., 522 pages. Cloth, $2.50.

FORMULARY OF THE PAPAL PENITENTIARY. In one

octavo volume of 221 pages, with frontispiece. Cloth, $2.50.

SUPERSTITION AND FORCE; ESSAYS ON THE WAGER

OF LAW, THE WAGER OF BATTLE, THE ORDEAL AND
TORTURE. Fourth edition, thoroughly revised. In one hand-
some royal 12mo. volume of 629 pages. Cloth, $2.75.

STUDIES IN CHURCH HISTORY. The Rise of the Temporal

Power — Benefit of Clergy — Excommunication. New edition. In one
handsome 12mo. volume of 605 pages. Cloth, $2.50.

AN HISTORICAL SKETCH OF SACERDOTAL CELIBACY

IN THE CHRISTIAN CHURCH. Second edition. In one hand-
some octavo volume of 685 pages. Cloth, $4.50.

LEHMANN (C. G.). A MANUAL OF CHEMICAL PHYSIOLOGY.
Jn one 8vo. volume of 327 pages, with 41 engravings. Cloth, $2,25.

BROTHERS & Co., PHILADELPHIA AND NEW YORK. 19

LIKES (SYLVAN H.). A POCKET TEXT-BOOK OF GENITO-
URINARY AND VENEREAL DISEASES. In one handsome
12mo. volume of about 350 pages, with many illustrations. Shortly.
Cloth, $1.50, net. Lea's Series of Pocket Text-booh, edited by BERN
B. GALLAUDET, M. D. See page 18.

LOOMIS (ALFRED L.) AND THOMPSON (W. OILMAN,
EDITORS). A SYSTEM OF PRACTICAL MEDICINE. In

Contributions by Various American Authors. In four very hand-
some octavo volumes of about 900 pages each, fully illustrated in
in black and colors. Complete work now ready- Per volume, cloth,
$5 ; leather, $6 ; half Morocco, $7. For sale by subscription only.
Full prospectus free on application to the Publishers. See American
System of Practical Medicine, page 2.

LUFF (ARTHUR P.). MANUAL OF CHEMISTRY, for the use of
Students of Medicine. In one 12mo. volume of 522 pages, with 36
engravings. Cloth, $2. See Student's Series of Manuals, page 27.

LYMAN (HENRY M.). THE PRACTICE OF MEDICINE. In one

very handsome octavo volume of 925 pages, with 170 engravings.
Cloth, $4.75 ; leather, $5.75.

Complete, concise, fully abreast of Practical, systematic, complete and

the times and needed by all students well balanced. — Chicago Med. Re-

and practitioners. — Univ. Med. Mag. carder.

An exceedingly valuable text-book.

LYONS (ROBERT D.). A TREATISE ON FEVER.
volume of 362 pages. Cloth, $2.25.

In one octavo

MACKENZIE (JOHN NOLAND). ON THE NOSE AND THROAT.

Handsome octavo, about 600 pages, richly illustrated. Preparing.

MAISCH (JOHN M.). A MANUAL OF ORGANIC MATERIA
MEDICA. New (7th) edition, thoroughly revised by H. C. C. MAISCH,
Ph. G., Ph. D. In one very handsome 12mo. volume of 512 pages, with
285 engravings. Just ready. Cloth, $2.50, net.

Used as text-book in every college
of pharmacy in the United States
and recommended in medical col-
leges.— American Therapist.

Noted on both sides of the Atlantic
and esteemed as much in Germany as

in America. The work has no equal.
— Dominion Med. Monthly.

The best handbook upon phar-
macognosy of any published in this
country. — Boston Med. & Sur. Jonr.

20 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

MALSBARY (GEORGE E.). A POCKET TEXT-BOOK OF
THEORY AND PRACTICE OF MEDICINE. In one handsome
12mo. volume of about 350 pages. Cloth, $1.50, net. Shortly. Lea's
Series of Pocket Text-books, edited by BERN B. GALLAUDET, M. D.
See page 18.

MANUALS. See Student's Quiz Series, page 27, Student's Series of
Manuals, page 27, and Series of Clinical Manuals, page 25.

MARSH (HOWARD). DISEASES OF THE JOINTS. In one 12mo.
volume of 468 pages, with 64 engravings and a colored plate. Cloth, $2.
See Series of Clinical Manuals, page 25.

MARTIN (EDWARD). A MANUAL OF SURGICAL DIAGNOSIS.
In one 12mo. volume of about 400 pp., fully illustrated. Preparing.

MARTIN (WALTON) AND ROCKWELL (WM. H.). A POCKET
TEXT-BOOK OF CHEMISTRY AND PHYSICS. In one hand-
some 12mo. volume of about 350 pages, with many illustrations. Cloth,
$1.50, net. Shortly. Lea's Series of Pocket Text-books, edited by
BERN B. GALLAUDET, M. D. See page 18.

MAY (C. H.). MANUAL OF THE DISEASES OF WOMEN. For
the use of Students and Practitioners. Second edition, revised by L.
S. RATJ, M. D. In one 12mo. volume of 360 pages, with 31 engrav-
ings. Cloth, $1.75.

MEDICALi NEWS POCKET FORMULARY, see page 32.

MITCHELL. (S. WEIR). CLINICAL LESSONS ON NERVOUS
DISEASES. In one 12mo. volume of 299 pages, with 19 engravings
and 2 colored plates. Cloth, $2.50. Of the hundred numbered copies
with the Author's signed title page a few remain ; these are offered
in green cloth, gilt top, at $3.50, net.

The book treats of hysteria, recur-
rent melancholia, disorders of sleep,
choreic movements, false sensations
of cold, ataxia, hemiplegic pain,
treatment of sciatica, erythromelal-
gia, reflex ocularneurosis, hysteric

contractions, rotary movements in
the feeble minded, etc. Few can
speak with more authority than the
author. — The Journal of the Ameri-
can Medical Association.

MITCHELL (JOHN K.). REMOTE CONSEQUENCES OF IN-
JURIES OF NERVES AND THEIR TREATMENT. In one
handsome 12mo. volume of 239 pages, with 12 illustrations. Cloth, $1.75.

Injuries of the nerves are of fre-
quent occurrence in private practice,
and often the cause of intractable
and painful conditions, conse-
quently this volume is of especial
interest. Doctor Mitchell has had

access to hospital records for the last
thirty years, as well as to the
government documents, and has
skilfully utilized his opportunities.
— The Med. Age.

MORRIS (MALCOLM). DISEASES OF THE SKIN. New (2d)
edition. In one 12mo. volume of 601 pages, with 10 chromo-litho-
graphic plates and 26 engravings. Cloth, $3.25, net. Just ready.

MULLER (J.). PRINCIPLES OF PHYSICS AND METEOROL-
OGY. In one large 8vo. vol. of 623 pages, with 638 cuts. Cloth, $4.50.

Magazine.

His descriptions of the diagnostic
manifestations of diseases are accu-
rate. This work will meet all the
requirements of student and physi-
cian.— The Medical News.

From its pages may be made the
diagnosis of every malady that
afflicts the human body, including
those which in general are dealt
with only by the specialist.— North-
western Lancet.

LEA BROTHEBS A Co., PHILADELPHIA AND NEW YORK. 21

MUSSER (JOHN H.). A PRACTICAL TREATISE ON MEDICAL
DIAGNOSIS, for Students and Physicians. New (3d) edition, thor-
oughly revised. In one octavo volume of about 1000 pages, with about
220 engravings and 48 full-page colored plates. In press.
Notices of previous edition are appended.

We have no work of equal value i It so thoroughly meets the precise
English. — University Medical demands incident to modern research

that it has been adopted as a leading
text-book by the medical colleges
of this country. — North American
Practitioner.

Occupies the foremost place as a
thorough, systematic treatise.— Ohio
Medical Journal.

The best of its kind, invaluable to
the student, general practitioner and
teacher. — Montreal Medical Journa I.

NATIONAL* DISPENSATORY. See Stille, Maisch & Caspari, p. 27.

NATIONAL FORMULARY. See Stille, Maisch & Caspari' s National
Dispensatory, page 27.

NATIONAL MEDICAL DICTIONARY. See Billings, page 4.

NETTLESHIP (E.). DISEASES OF THE EYE. New (5th) American
from sixth English edition, thoroughly revised. In one 12mo. volume
of 521 pages, with 161 engravings, and 2 colored plates, test-types,
formulae and color-blindness test. Cloth, $2.25. Just ready.

By far the best student's text-book English language. — Journal of
on the subject of ophthalmology and ! Medicine and Science.
is conveniently and concisely ar- j The present edition is the result
ranged. — The Clinical Review. of revision both in England and

It has been conceded by ophthal- j America, and therefore contains the
mologists generally that this work latest and best ophthalmological

for compactness, practicality and ideas of both continents. — The Phy~
rness has no superior in the ; sician and Surgeon.

clearness

NICHOLS (JOHN B.) AND VALE (F. P.). A POCKET TEXT-
BOOK OF HISTOLOGY AND PATHOLOGY. In one handsome
I2mo. volume of about 350 pages, with many illustrations. In press.
Cloth, $1.50, net. Lea's Series of Pocket, Text-books, edited by BERN
B. GALLAUDET, M. D. See page 18.

NORRIS (WM. F.) AND OLIVER (CHAS. A.). TEXT-BOOK OF
OPHTHALMOLOGY. In one octavo volume of 641 pages, with 357
engravings and 5 colored plates. Cloth, $5 ; leather, $6.

A safe and admirable guide, well best, the safest and the most conir re-
qualified to furnish a working ! hensive volume upon the subject that
knowledge of ophthalmology. — has ever been offered to the Ainer-

Johns Hopkins Hospital Bulletin.

It is practical in its teachings.
We unreservedly endorse it as the

ican medical public. — Annals of
Ophthalmology and Otology.

22 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

OWEN (EDMUND). SURGICAL DISEASES OF CHILDREN.

In one 12mo. volume of 525 pages, with 85 engravings and 4 colored
plates. Cloth, $2. See Series of Clinical Manuals, page 25.

PARK (ROSWELL,). A TREATISE ON SURGERY BY AMERI-
CAN AUTHORS. New and condensed edition. In press. In one
royal octavo volume of about 1250 pages, with about 1000 engravings
and many full-page plates. ^g^-This work is also published in a
larger edition, comprising two volumes. Volume I., General Surgery,
799 pages, with 356 engravings and 21 full-page plates, in colors and
monochrome. Volume II., Special Surgery, 800 pages, with 430 engra-
vings and 17 full-page plates, in colors and monochrome. Per volume,
cloth, $4.50 ; leather, $5.50. Net.

The work is fresh, clear and practi- 1 way that they add great force to the
cal, covering the ground thoroughly text.— The Chicago Medical Ee-
yet briefly, and well arranged for corder.

rapid reference, so that it will be of j The various writers have em-
special value to the student and busy j bodied the teachings accepted at
practitioner. The pathology is ! the present hour.— The Nort h Amer-
broad, clear and scientific, while the ! ican Practitioner.
suggestions upon treatment are Both for the student and practi-
clear-cut, thoroughly modern and I tioner it is most valuable. It is
admirably resourceful.— Johns Hop- thoroughly practical and yet thor-
kins Hospital Bulletin. \ oughly scientific. — Medical News.

The latest and best work written j A truly modern surgery, not only
upon the science and art of surgery. • in pathology, but also in sound
Columbus Medical Journal. surgical therapeutics. — New Or-

The illustrations are almost en- ! leans Med. and Surgical Journal.
tirely new and executed in such a

PARK (WILLIAM H.). BACTERIOLOGY IN MEDICINE AND
SURGERY. 12mo., about 550 pages, fully illustrated. In press.

PARRY (JOHN S.). EXTRA-UTERINE PREGNANCY, ITS
CLINICAL HISTORY, DIAGNOSIS, PROGNOSIS AND TREAT-
MENT. In one octavo volume of 272 pages. Cloth, $2.50.

PARVIN (THEOPHELUS). THE SCIENCE AND ART OF OB-
STETRICS. Third edition. In one handsome octavo volume of
677 pages, with 267 engravings and 2 colored plates. Cloth, $4.25 ;
leather, $5.25.

In the foremost rank among the
most practical and scientific medical
works of the day. — Medical News.

It ranks second to none in the
English language. — Annals of Gyne-
cology and Pediatry.

The book is complete in every de-
partment, and contains all the neces-
sary detail required by the modern

practising obstetrician. — Interna-
tional Medical Magazine.

Parvin's work is practical, con-
cise and comprehensive. We com-
mend it as first of its class in the
English language. — Medical Fort-
nightly.

It is an admirable text-book in
every sense of the word. — Nashville
Journal of Medicine and Surgery.

LEA BBOTHEKS & Co., PHILADELPHIA AND NEW YORK. 23

PEPPER'S SYSTEM OF MEDICINE. See page 3.

PEPPER (A. J.). FORENSIC MEDICINE. In press. See Student's
Series of Manuals, page 27.

SURGICAL PATHOLOGY. In one 12mo. volume of 511 pages,

with 81 engravings. Cloth, $2. See Student's Series of Manuals, p. 27.

PICK (T. PICKERING). FRACTURES AND DISLOCATIONS.
In one 12mo. volume of 530 pages, with 93 engravings. Cloth, $2.
See Series of Clinical Manuals, page 25.

PLAYFAIR (W. 8.). A TREATISE ON THE SCIENCE AND
PRACTICE OF MIDWIFERY. Seventh American from the ninth
English edition. In one octavo volume of 700 pages, with 207
engravings and 7 plates. Cloth, $3.75 net ; leather, $4.75, net. Just
ready.

In the numerous editions which obstetrician. It holds a place among
have appeared it has been kept con- the ablest English-speaking authori-

stantly in the foremost rank. It is
a work which can be conscientiously
recommended to the profession. —
The Albany Medical Annals.

This work must occupy a fore-
most place in obstetric medicine as
a safe guide to both student and

ties on the obstetric art. — Buffalo
Medical and Surgical Journal.

An epitome of the science and
practice of midwifery, which em-
bodies all recent advances. — The
Medical Fortnightly.

THE SYSTEMATIC TREATMENT OF NERVE PROSTRA-
TION AND HYSTERIA. In one 12mo. volume of 97 pages.
Cloth, $1.

POCKET FORMULARY, see page 32.
POCKET TEXT-BOOKS, see page 18.

POLJTZER (ADAM). A TEXT-BOOK OF THE DISEASES OF THE
EAR AND ADJACENT ORGANS. Second American from the
third German edition. Translated by OSCAR DODD, M. D., and
edited by SIB WILLIAM DALBY, F. R. C. S. In one octavo volume of
748 pages, with 330 original engravings. Cloth, $5.50.

The anatomy and physiology of ment are clear and reliable. We
each part of the organ of hearing can confidently recommend it, for it
are carefully considered, and then contains all that is known upon the
follows an enumeration of the dis- subject. — London Lancet.
eases to which that special part of A safe and elaborate guide into
the auditory apparatus is especially every part of otology. — American
liable. The indications for treat- Journal of the Medical Sciences.

POTTS (CHARLES S.). A POCKET TEXT-BOOK OF NERVOUS
AND MENTAL DISEASES. In one handsome 12mo. volume of
about 450 pages. Cloth, £1. 50, net. Shortly. Lea's Series of Pocket
Text-books, edited by BERN B. GALLAUDET, M. D. See page 18.

PROGRESSIVE MEDICINE, see page 32.

PURDY (CHARLES WA BRIGHT'S DISEASE AND ALLIED
AFFECTIONS OF THE KIDNEY. In one octavo volume of 288
pages, with 18 engravings. Cloth, $2.

24 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

PYE-SMITH (PHELBP H.). DISEASES OF THE SKIN. In one
12mo. vol. of 407 pp., with 28 illus., 18 of which are colored. Cloth, $2.

QUIZ SERIES. See Student's Quiz Series, page 27.

RALFE (CHARLES H.). CLINICAL CHEMISTRY. In one

12mo. volume of 314 pages, with 16 engravings. Cloth, $1.50. See
• Student's Series of Manuals, page 27.

RAMSBOTHAM (FRANCIS H.). THE PRINCIPLES AND PRAC-
TICE OF OBSTETRIC MEDICINE AND SURGERY. In one
imperial octavo volume of 640 pages, with 64 plates and numerous
engravings in the text. Strongly bound in leather, $7.

REICHERT (EDWARD T.). A TEXT-BOOK ON PHYSIOLOGY.

In one handsome octavo volume of about 800 pages, richly illustrated.
Preparing.

REMSEN (IRA). THE PRINCIPLES OF THEORETICAL CHEM-
ISTRY. New (5th) edition, thoroughly revised. In one 12mo. vol-
ume of 326 pages. Cloth, $2.

A clear and concise explanation
of a difficult subject. We cordially
recommend it. — The London Lancet.

The book is equally adapted to the
student of chemistry or the practi-
tioner who desires to broaden his
theoretical knowledge of chemistry.
— New Orleans Med. and Surg. Jour.

The appearance of a fifth edition
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that the work has met with general
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lated into German and Italian. The
treatise is especially adapted to the
laboratory student. It ranks unusu-
ally high among the works of this
class. This edition has been brought
fully up to the times. — American
Medico- Surgical Bulletin.

RICHARDSON (BENJAMIN WARD). PREVENTIVE MEDI-
CINE. In one octavo volume of 729 pages. Cloth, $4 ; leather, $5.

ROBERTS (JOHN B.). THE PRINCIPLES AND PRACTICE OF
MODERN SURGERY. New (2d) edition. In one octavo volume of
about 800 pages, with about 500 engravings. Shortly.

THE COMPEND OF ANATOMY. For use in the Dissecting

Room and in preparing for Examinations. In one 16mo. volume of
196 pages. Limp cloth, 75 cents.

ROBERTS (SIR WILLIAM). A PRACTICAL TREATISE ON
URINARY AND RENAL DISEASES, INCLUDING URINARY
DEPOSITS. Fourth American from the fourth London edition. In
one very handsome 8vo. vol. of 609 pp., with 81 illus. Cloth, $3.50.

ROBERTSON (J. MCGREGOR). PHYSIOLOGICAL PHYSICS.
In one 12mo. volume of 537 pages, with 219 engravings. Cloth, $2.
See Student's Series of Manuals, page 27.

ROSS (JAMES). A HANDBOOK OF THE DISEASES OF THE
NERVOUS SYSTEM. In one handsome octavo volume of 726 pages,
with 184 engravings. Cloth, $4.50 ; leather, $5.50.

SAVAGE (GEORGE H.). INSANITY AND ALLIED NEUROSES,
PRACTICAL AND CLINICAL. In one 12mo. volume of 551 pages,
with 18_ typical engravings. Cloth, $2. See Series of Clinical Man-
ualt, page 25.

LEA BBOTHEES & Co., PHILADELPHIA AND NEW YOEK. 25

SCHAFER (EDWARD A.). THE ESSENTIALS OF HISTOL-
OGY. DESCRIPTIVE AND PRACTICAL. For the use of Students.
New (5th) edition. In one handsome octavo volume of 359 pages,
with 392 illustrations. Cloth, $3.00, net. Just ready.
Nowhere else will the same very I The most satisfactory elementary

moderate outlay secure as thoroughly text-book of histology in the Eng-

useful and interesting an atlas of j lish language. — The Boston Med. and

structural anatomy. — The American Sur. Jour.

Journal of the Medical Sciences.

A COURSE OF PRACTICAL HISTOLOGY. New (2d) edition.

In one 12mo. volume of 307 pages, with 59 engravings. Cloth, $2.25.

The book very nearly approaches
perfection. Methods are given with
an accuracy of detail and prevision
of difficulties which can hardly be

overpraised. It bears eloquent tes-
timony to the wide knowledge and
untiring industry of its author. —
The Scottish Med. and Surg. Jour.

SCHLEIF (WILLIAM). MATERIA MEDICA, THERAPEUTICS,
PRESCRIPTION WRITING, MEDICAL LATIN, ETC. 12mo.,
352 pages. Cloth, $1.50, net. Just ready. Lea's Series of Pocket
Text-books. Edited by BERN B. GALLAUDET, M. D. See page 18.

SCHMTTZ AND ZUMPT'S CLASSICAL SERIES. Advanced
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cises. Cloth, 50 cents. Sallust. Cloth, 60 cents. Nepos. Cloth, 60
cents. Virgil. Cloth, 85 cents. Curtius. Cloth, 80 cents.

SCHOFEELD (ALFRED T.). ELEMENTARY PHYSIOLOGY

FOR STUDENTS. In one 12mo. volume of 380 pages, with 227
engravings and 2 colored plates. Cloth, $2.

SCHREIBER (JOSEPH). A MANUAL OF TREATMENT BY
MASSAGE AND METHODICAL MUSCLE EXERCISE. Octavo
volume of 274 pages, with 117 engravings.

SENN (NICHOLAS). SURGICAL BACTERIOLOGY. Second edi-
tion. In one octavo volume of 268 pages, with 13 plates, 10 of which
are colored, and 9" engravings. Cloth, §2.

SERIES OF CLINICAL MANUALS. A Series of Authoritative
Monographs on Important Clinical Subjects, in 12mo. volumes of about
550 pages, well illustrated. The following volumes are now ready :
YEO on Food in Health and Disease, new (2d) edition, $2.50; CARTER
and FROST'S Ophthalmic Surgery, $2.25 ; HUTCHINSON on Syphilis,
$2.25; MARSH on Diseases of the Joints, $2; OWEN on SurgicalDis-
eases of Children, $2; PICK on Fractures and Dislocations, $2; SAVAGE
on Insanity and Allied Neuroses, $2.
For separate' notices, see under various authors' names.

SERIES OF STUDENT'S MANUALS. See page 27.

SIMON (CHARLES E.). CLINICAL DIAGNOSIS, BY MICRO-
SCOPICAL AND CHEMICAL METHODS. New (2d) edition. In
one very handsome octavo volume of 530 pages, with 135 engravings
and 14 full-page colored plates. Cloth, $3.50. Just ready.

This book thoroughly deserves its j In all respects entirely up to date,
success. It is a very complete, authen- 1 — Medical Record.
tic and useful manual of the micro- ; The chapter on examination of
scopical and chemical methods j the urine is the most complete and
which are employed in diagnosis, j advanced that we know of in the
Very excellent colored plates illus- i English language. — Canadian Prac-

trate this work.— New York Medical
Journal.

titioner.

26 LEA BROTHERS & Co., PHILADELPHIA AND NEW YORK.

SIMON (W.). MANUAL OF CHEMISTRY. A Guide to Lectures
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It is difficult to see how a better i the covers of this book. — The North-
book could be constructed. No man western Lancet.
who devotes himself to the practice Its statements are all clear and its
of medicine need know more about j teachings are practical. — Virginia
chemistry than is contained between | Med. Monthly.

SLADE (D. D.). DIPHTHERIA; ITS NATURE AND TREAT-
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SMITH (EDWARD). CONSUMPTION; ITS EARLY AND REME-
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i j.1 i_ *j-|_i«i ,1 t. ,• rt,i°

tory text-book with which we are
acquainted. — American Gynecologi-
cal and Obstetrical Journal.

It truly is the most evenly bal-
anced, clear in description and
thorough in detail of any of the
books published in this country on

any other work treating of the same
subj ect. — A merican Medico- Surgica I
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A safe guide for students and phy-
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For years the leading text-book on
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this subject.— Medical Fortnightly. \ Chicago Medical Recorder.
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The book is admirably planned,
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Every practitioner of medicine
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physician, and invaluable to the
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It, is the official guide for the Med-
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The readiness with which the vast

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STIMSON (LEWIS A.). A MANUAL OF OPERATIVE SURGERY.

New (3d) edition. In one royal 12mo. volume of 614 pages, with 306
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A useful and practical guide for
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STIMSON (LEWIS A.). A TREATISE ON FRACTURES AND

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to his conclusions an unimpeachable Pointed, practical, comprehensiv e,

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By long odds the best work on
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In the observation and treatment
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The clearest, most unbiased and
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TAYL.OR (ROBERT W.). A PRACTICAL TREATISE ON SEX-
UAL DISORDERS IN THE MALE AND FEMALE. In one
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$3. Net.

It is a timely, boon to the medical
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the female is presented in an exhaus-
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patients intelligently. Sterility in I Medical News.

A CLINICAL ATLAS OF VENEREAL AND SKIN DISEASES.

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TAYLOR (SEYMOUR). INDEX OF MEDICINE. A Manual for
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802 pages. Cloth, $3.75.

THOMAS (T. GAELL.ARD) AND MUNDE (PAUL P.). A PRAC
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The best practical treatise on the
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It will be of especial value to the
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This work, which has already gone
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satisfactory. Many of them are new | the most complete treatise upon the
and are particularly clear and attrac- j subject. — The Archives of Gynecol-
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THE PATHOLOGY AND TREATMENT OF STRICTURE

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THOMSON (JOHN). DISEASES OF CHILDREN. In one crown
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TODD (ROBERT BENTL.EY). CLINICAL LECTURES ON CER-
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TREVES (FREDERICK). OPERATIVE SURGERY. In two
8vo. vols. containing 1550 pp., with 422 illus. Cloth, $9 ; leath., $11.

A SYSTEM OF SURGERY. In Contributions by Twenty-five

English Surgeons. In two large octavo volumes. Vol. I., 1178 pages,
with 463 engravings and 2 colored plates. Vol. II., 1120 pages, with
487 engravings and 2 colored plates. Complete work, cloth, $16.00.

30 LEA BBOTHEES & Co., PHILADELPHIA AND NEW YOEK.

TREVES (FREDERICK). SURGICAL APPLIED ANATOMY. In
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Student's Series of Manuals, page 27.

TUTTL.E (GEORGE M.). A POCKET TEXT-BOOK OF DISEASES
OF CHILDREN". In one handsome 12mo. volume of about 300 pages,
with many illustrations. Cloth, $1.50, net. Shortly. Lea's Series of
Pocket Text-looks, edited by BERN B. GALLATTDET, M. D. See p 18.

VAUGHAN (VICTOR C.) AND NOVY (FREDERICK G.).

PTOMAINS, LEUCOMAINS, TOXINS AND ANTITOXINS,
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In one 12mo. volume of 603 pages. Cloth, $3.

The work has been brought down
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The most exhaustive and most re-
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American Jour, of the Med. Sciences.

The present edition has been not,
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VISITING L.IST. THE MEDICAL NEWS VISITING LIST for 1899.
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to advance-paying subscribers to THE MEDICAL NEWS or THE
AMERICAN JOURNAL OF THE MEDICAL SCIENCES, or both. See p. 32.

WATSON (THOMAS). LECTURES ON THE PRINCIPLES AND
PRACTICE OF PHYSIC. A new American from the fifth and
enlarged English edition, with additions by H. HARTSHORNE, M. D .
In two large 8vo. vols. of 1840 pp., with 190 cuts. Cloth, $9 ; leather, $1 1 .

WEST (CHARLES). LECTURES ON THE DISEASES PECULIAR
TO WOMEN. Third American from the third English edition. In
one octavo volume of 543 pages. Cloth, $3.75 ; leather, $4.75.

ON SOME DISORDERS OF THE NERVOUS SYSTEM IN

CHILDHOOD. In one small 12mo. volume of 127 pages. Cloth, $1.

WHARTON (HENRY R.). MINOR SURGERY AND BANDAG-
ING. New (4th) edition. In one 12mo. vol. of about 600 pages, with
about 500 engravings, many of which are photographic. Shortly.
Notices of previous edition are appended.

We know of no book which more
thoroughly or more satisfactorily
covers the ground of Minor Surgery
and Bandaging. — Brooklyn Medical
Journal.

Well written, conveniently ar-
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covers the field so fully as to render
it a valuable text-book, as well as a

work of ready reference for sur-
geons.— North Amer. Practitioner.
The part devoted to bandaging is
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subject in the English language. It
can be highly commended to the
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WHITLA (WILLIAM). DICTIONARY OF TREATMENT, OR
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WILLIAMS (DAWSON). THE MEDICAL DISEASES OF CHIL-
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Just ready. Cloth, $2.50, net.

The descriptions of symptoms are j diagnoses, prognosis, complications,
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each disease are given the symptoms, Medical Journal.

WILSON (ERASMUS). A SYSTEM OF HUMAN ANATOMY.

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We doubt whether any book on | work of Dr. Yeo's. The value of

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— New York Medical Journal.

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YOUNG (JAMES K.). ORTHOPEDIC SURGERY. In one 8vo.
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In studying the different chapters, surgical specialty and every page

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