Af ric. Dent.

Main Lib.

BIOLOGY
r LIBRAHK

XI A N l_J A.

HISTOLOCf AND BACTERIOLOGI

INCLUDING

A CONCISE STATEMENT OF THE IMPORTANT FACTS OF
MICROSCOPIC TECHNIQUE AND URINALYSIS,

A LABORATORY COURSE OF SEVENTY PRACTICAL EXERCISES

PROVISION FOR NOTES AND DRAWINGS.

BY

WILLIAM OSBURN, A. M.

Professor of Histology, Bacteriology, and Botany,
Meharry Medical College.

18W9,

PRESS OF THE MARSHALL & BRUCE COMPANY,
NASHVILLE, TENN.

COPYRIGHT, 1899,

BY

WILLIAM OSBURN.

TWO COPIES RECEIVED.

COPY,

CONTENTS.

PAGE.

PREFACE 5

INTRODUCTION 7

PART 1.— MICROSCOPY.

CHAPTER I. — Microscope and Accessories 8

CHAPTER II. — Microscopic Technique 16

CHAPTER III. — Reagents and Stains 30

PART 2.— HISTOLOGY.

CHAPTER IV.— The Cell 35

CHAPTER V. — Tissues and Organs 53

CHAPTER VI.— The Blood 55

CHAPTER VII. — Epithelial Tissues and Endothelium .. 61

CHAPTER VIII. — Connective Tissues 66

CHAPTER IX. — Muscular Tissues 75

CHAPTER X. — Nervous Tissues and Systems 79

CHAPTER XI. — The Circulatory System 92

CHAPTER XII. — The Lymphatic System 96

CHAPTER XIII. — Membranes and Glands 100

CHAPTER XIV.— The Skin . . .... . 106

CHAPTER XV. — The Alimentary Canal Ill

CHAPTER XVI. — The Liver 118

CHAPTER XVII.— The Tongue and the Teeth 121

CHAPTER XVIII. — The Respiratory System 127

CHAPTER XIX. — The Kidney and Urinary Tract 131

CHAPTER XX. — The Genital Organs 135

CHAPTER XXL— The Eye, Ear, and Nose 141

PART 3.— BACTERIOLOGY.

CHAPTER XXII. — Characteristics and Classification of

Bacteria 143

[3]

268471

4 CONTENTS.

CHAPTER XXIII. — Morphology, Kinds, and Products. . 145

CHAPTER XXIV. — Size, Numbers, and Distribution. . . 149
CHAPTER XXV. — Cultivation and Systematic Study of

Bacteria 151

CHAPTER XXVI. — Microscopic Technique 156

CHAPTER XXVII. — Non-Pathogenic Bacteria 160

CHAPTER XXVIII. — Pathogenic Bacteria 164

CHAPTER XXIX. — Toxins, Immunity, Germicides, etc. . 170

PART 4.— URINALYSIS.

CHAPTER XXX. — Physical, Chemical, and Microscopic

Urinalysis 172

PREFACE.

This modest manual has been prepared by the writer for his
classes in Histology and Bacteriology. The condensed statement of
many important facts of these subjects will be appreciated by those
who have a limited amount of time for their study. The absence
of diagrams may be a disappointment to some and, at first thought,
appear as a disadvantage; but the study of nature is primarily the
study of objects, and not of books and diagrams, though these are ad-
mitted helps. Its end should be the interpretation of facts and the
demonstration of truth, and this is accomplished by going direct to
nature, the source of facts and the embodiment of truth. A fact
is any reality, and truth is the correspondence between a proposition
and a reality — a quality rather than an essence, the substantive sug-
gested by the adjective true. Not every proposition is true, but
every reality in nature embodies a truth. When we prove the agree-
ment between a proposition and the real thing at issue we demon-
strate the truth. The same thing is accomplished,, and doubt-
less a higher discipline attained, when we accurately observe a re-
ality of nature and then frame a proposition that truthfully ex-
presses that reality. One of the highest acts of the human mind is
correctly to observe a fact and accurately state the truth embodied
in that fact. A diagram may embody the truth. When a student
correctly interprets nature and then prepares a diagram that truth-
fully represents that interpretation, he has performed an act of the
highest disciplinary and practical value. Nothing will convey to the
mind of the teacher a student's conception of a subject so fully as
an effort on the part of that student to represent by a diagram that
which he observes. It is well, therefore, to encourage students
to copy nature rather than the conceptions of others, even though
their delineations may at times appear crude. The motto of the
teacher should be : " Nothing goes in this laboratory without draw-

ings."

[5]

6 PREFACE.

The provision made for drawings in this manual will greatly facil-
itate that work. The foot-notes will indicate what the student is
to observe and illustrate, and by lettering the structures drawn, as
indicated in the descriptive foot-note, time and labor will be saved.
In connection with this work, black-board diagrams, hand-made
charts, and lantern projections can be used, that the student may
have the clearest possible conception of what the microscope reveals
before beginning his task with pencil or pen.

A word to the student will not be amiss. The faithful student
will not be content to let another do his work. He will be deter-
mined to make every demonstration count. He will strive to be ac-
curate in his observations and painstaking in his notes and draw-
ings. Blots, finger marks and erasures will be studiously avoided.
In the laboratory he will keep everything in its place and clean up
after each exercise. He will not be satisfied with the statements
of one author, but will seek information from every available source.
These seem minor things, but they enter into character. Like
straws, they show the direction of the current.

The writer desires to acknowledge his gratitude to kind friends
for encouragement, and especially to Dr. G. W. Hubbard, Dean
of Meharry Medical College, and J. H. Holman, M.D. , Instructor
in Histology and Bacteriology. He is under obligation to many
sources for the materials herein presented, but more especially to
the valuable texts of Stirling and Piersol on Histology, and of Mc-
Farland and Williams on Bacteriology. The student who would in-
vestigate these subjects more thoroughly is advised to secure one or
more of these works. The writer is aware that no new facts are
herein presented, and is fully conscious of the imperfections and
shortcomings of this manual, but hopes that the plan proposed will
be of service to some, and with this hope sends it forth to accom-
plish its purpose among others of kindred nature.

WILLIAM OSBURN.
NASHVILLE. TENX., Aug-ust, 1899.

INTRODUCTION.

The scope of this manual is intended to cover a brief statement of
the important facts of Microscopy, Histology, Bacteriology, and
Urinalysis.

Microscopy, in a liberal sense, is the microscopic study of natural
objects. In a more restricted sense, it is the study of the microscope,
its structure and manipulation, and of microscopic technique.

Histology is that department of Biology which treats of the mi-
nute anatomy of plants and animals. Animal Histology deals with
the microscopic structure of animals ; Vegetable Histology, with that
of plants. Animal Histology consists of two departments — name-
ly, Normal Histology and Pathology. Normal Histology deals with
cells and tissues in their normal, or healthy, state. Pathology deals
with these structures as affected by disease. There is an intimate
relation between Normal Histology and Pathology. Disease affects
the cells, and the student must understand the character of the cells
in a condition of health before he can adequately comprehend their
pathological condition.

Bacteriology is that department of Botany which treats of bac-
teria— minute, unicellular, chlorophylless fission-plants.

Urinalysis is the examination of the urine by physical, chemical,
and microscopical tests, by means of which its normal or patholog-
ical condition is determined.

[7]

I.

MICROSCOPY.

CHAPTEE I.
THE MICROSCOPE AND ACCESSORIES.

The microscope is a lens or combination of lenses designed to aid
the eye in the examination of minute objects.

KINDS OF MICROSCOPES.

There are two kinds of microscopes, simple and compound. A
simple microscope is a single lens (or group of lenses) which is so
used that the object to be examined is between the focus and the
lens. It produces an erect virtual image. A compound microscope
is a combination of lenses, by means of which an inverted image is
produced, and this is viewed by the eye, not the real object.

STRUCTURE OF THE COMPOUND MICROSCOPE.

The following parts should be carefully studied, and the use of
each part thoroughly understood:

The base rests upon the table and supports all the other parts.

The pillar is the upright column which supports the arm.

The arm is attached to and works upon the pillar by means of
the hinge-joint.

The reflector is the mirror by which the object to be examined is
illuminated.

The stage is the platform upon which rests the slide containing
the preparation to be studied. Clips are springs attached to the
stage to hold the slide in position.

The aperture is the circular opening in the stage.

The diaphragm is the circular disk which regulates the amount
of light required for illumination.

The body is the cylindrical attachment supported by the arm.

The draw-tube is the tube which moves within the body.
[8]

THE MICROSCOPE.

9

The nose-piece is attached to the lower end of the body and bears
the objectives.

The objective is the lens attached to the body or nose-piece. It
often consists of several pieces of glass cemented together.

The objectives commonly used are the two-thirds, one-sixth, and
one-twelfth inch. By a two-thirds inch objective is meant one whose
magnifying power is equal to that of a lens whose focal length is
two-thirds of an inch.

The eye-piece comprises the lenses which fit into the upper end
of the draw-tube. It contains a field-glass and eye-glass, each a
piano convex lens, with the convex surface downward.

The coarse-adjustment consists of the two vertical milled-heads
and the rack and pinion.

The fine-adjustment is secured by the horizontal milled-head.

Laboratory exercise No. 1. — Examine a compound microscope and
make out each part named above. Make a study of the diagram on page
10.

Substage Attachment with. Condenser.

Bausch «k Lomb Optical Co., Rochester, N. Y.

MICROSCOPE, SHOWING PARTS.

Bausch & Lomb Optical Co., Rochester, N. Y.

Parts: A, base; B, pillar; C. arm; D, body; E, nose-piece; F. ojectives; G-,
eye-piece; H, draw-tube; I, collar; J, coarse-adjustment; K, milled-heads; L,
fine-adjustment; M, stage; N, clips; O, mirror; P, mirror-bar; Q, substage; R,
substagebar; S, diaphragm.

THE MICROSCOPE.

11

PHYSICAL PRINCIPLES.

The image produced by a compound microscope is a magnified
inverted real image. Imagine an innumerable number of lines
proceeding from the object to be examined in a direction perpen-
dicular to the long axis of the objective. These lines represent the
rays of light proceeding from all points of the object. As they pass
through the objective they are bent, or refracted, and converged to
a common point called the principal focus. No image is produced
at this focus. The accompanying diagram illustrates how this focus
is produced.

A B, object; C, lens; F, principal focus.

It is at the conjugate foci that the image is formed. There are
as many conjugate foci as there are emergent points on the sur-
face of the object. They are situated between the principal focus
and the eye-piece. Let us suppose an innumerable number of emer-
gent rays of light to have proceeded from any point of the object.
These rays, striking the lens of the objective upon every point
of its surface, are refracted and converged to a point called the
conjugate focus. The following diagram will illustrate how the

A B, object; O, objective; A and B', conjugate foci; E, eye-piece; A B', in-
verted image produced by the objective; A" B" magnified inverted image viewed
by the eye.

12 MICROSCOPY.

image is formed at the conjugate focus and hew this image is mag-
nified by the eye-piece, thus producing the magnified, inverted, real
image which is viewed by the eye of the observer.

MANIPULATION AND CARE OF A MICROSCOPE.

Handling.

The microscope should be handled with more than ordinary care.
In moying it from place to place it should be caught firmly by the
pillar. Reagents of any kind should not be allowed to come in con-
tact with it. Alcohol will destroy the lacquer, and acids will pro-
duce corrosion of its surface. The hands, therefore, should be kept
perfectly clean.

Cleansing.

The microscope may be cleaned with a linen cloth. Reagents
should not be used in cleansing the objectives and eye-piece without
the direction of the teacher. To remove balsam from the objective,
alcohol or xylol may be used, but should be quickly removed with
Japanese paper, a soft paper especially used for cleaning lenses.

Obtaining a Focus.

To obtain a focus, place the slide upon the stage so that the ob-
ject to be examined appears in the center of the aperture; adjust the
reflector so as to illuminate the object. Lower the objective by
means of the coarse-adjustment until it is below the focal point;
then, with the eye at the eye-glass, work upward until the object ap-
pears, making the focusing perfect by means of the fine-adjustment.

Cautions.

To save harm to the eyes in the use of the microscope it is a good
plan to keep both eyes open; let the eye be used as though viewing
some distant object; there should be no conscious strain to obtain a
focus, but let the hand with fine-adjustment aid the eye ; do not use
the microscope long at a time, so as to produce an aching sensation
in the eye.

Allow nothing to touch the lenses, except Japanese paper or soft
linen, which may be used in cleaning them.

THE MICROSCOPE. 13

ACCESSORIES.

The sub-stage. — This is an attachment supported beneath the
stage and is designed to receive the iris diaphragm, Abbe condenser,
.etc.

Iris diaphragm. — This is supported by the sub-stage and is so
constructed that the aperture for admitting light may be regulated
by turning a milled-head.

Abbe condenser. — This is an apparatus containing a lens of very
short focus, and is capable of producing intense illumination. It
is supported by the sub-stage.

Mechanical stage. — This is attached to the microscope so as to
work above the stage, and is designed to hold the slide and so change
its position as to bring every part of the object into the field of view.

Camera Lucida. — This is an apparatus which is attached to the
tube of the microscope, and is designed to assist in making diagrams
of the object .studied.

Polariscope. — Polarization consits in reducing vibrations of light
to one plane. This is accomplished by the polariscope, which con-
sists of a polarizer and an analyzer. The polarizer consists of a
crystal of Iceland spar, which by double refraction separates the or-
dinary from the extraordinary ray. The analyzer generally used is a
Nicol's prism, which consists of a crystal of Iceland spar split diag-
onally and the pieces then cemented together with Canada balsam.
The Canada balsam produces the total reflection of the ordinary ray,
while the extraordinary ray passes through. The analyzer is used
to detect polarized light.

Micrometer. — There are two kinds ofmicrometers — the stage mi-
crometer and the eye-piece micrometer. The stage micrometer is
a small glass slide, upon which is a graduated scale, the graduations
being in millimeters and tenths of a millimeter. It is used in de-
termining the magnifying power of the microscope.

Laboratory exercise No. 2. — To obtain a focus. Place upon the stag-e
a prepared slide; adjust the reflector so as to illuminate the object;
using- first the low power, by means of the coarse-adjustment lower
the objective until it is below the focal point. If the objective be a
two-thirds inch, the focal point will be somewhat less than two-thirds
of an inch from the object. Now, with the eye at the eye-piece work
upward until the object appears in view^ Perfect the focusing- by using-

14 MICEOSCOPY.

the fine-adjustment. When using- the microscope it is always a good
plan to keep the hand upon the fine-adjustment, using- it constantly
to bring- different planes of the object into the field of vision.

To determine the magnifying power. Place upon the stage a stage-mi-
crometer and focus with both eyes open. The lines upon the microm-
eter will also be seen by the eye not in use. Place under the microscope
or upon the stage a sheet of white paper. Now, with a pencil mark
the apparent, or magnified, distance between two lines. Knowing the
real distance, one-tenth of a millimeter, the magnification can readily
be determined. For example, should the magnified distance between
two lines be thirty millimeters, the real distance being one-tenth of
a millimeter, the magnification would therefore be ten times thirty,
or 300.

Microtome. — The microtome is an apparatus employed in cutting
microscopic sections of tissues. It is provided with a microtome
knife, a knife-carrier, and the milled-head which operates a mechan-
ism for regulating the thickness of the sections. The student micro-
tome manufactured hy the Bausch & Lomb Optical Company, of
Eochester, N. Y., is a most excellent instrument for all ordinary
work.

Paraffin Bath. — This is designed for use in infiltrating and em-
bedding tissues in paraffin. The heat should be so regulated as
to keep the paraffin as near the melting point as possible. Where
gas is available this may be accomplished by means of a thermostat.

Cornet Forceps. — This is a forceps especially useful in holding
cover-glasses when staining preparations of sputum, bacteria, etc.

Centrifuge. — This apparatus utilizes the centrifugal tendency
and is employed to separate substances of different specific gravity.
It is provided with two important attachments, the sedimentation
tubes and carrier and the haematokrit. The sedimentation tube
contains fifteen cubic centimeters and is graduated into 100 equal
parts, up to ten cubic centimeters, and above that each cubic centi-
meter is graduated into four equal parts for the measurement of re-
agents employed. Tty means of these the solid matter in urine,
water, etc. may be precipitated and the exact per cent determined.

The haematokrit is provided with graduated tubes; each tube is
fifty millimeters in length and is divided into 100 equal parts. The
diameter of the bore is 0.5 millimeter. These tubes are used in deter-
mining the percentage composition of the blood. By revolving the
handle of the centrifuge seventy-seven times in a minute the haema-

THE MICROSCOPE. 15

tokrit is caused to rotate 5,000 times. This rapid rotation precipitates
to the outer end of the tube the red blood corpuscles, which are of
the highest specific gravity. Next to these will be arranged the white
corpuscles, which are heavier than the plasma, while the plasma
fills the remaining portion of the tube. A tube is also provided for
sputum, by means of which bacteria may be precipitated, thus in-
creasing the accuracy of a microscopic analysis.

Slide and Cover-glass. — The slide consists of a piece of glass one
inch wide and thige inches long, and is used to receive the object
to be examined. The cover-glass is a thin piece of glass, rectangular
or circular in shape. In cleaning slides and cover-glasses, tissue paper
or a linen towel may be used. They should always be seized by their
edges, never allowing the fingers to touch the flat surfaces.

Student Microtome.

Bausch & Lomb Optical Co., Rochester, N. Y.

NOTE. — Nearly all the illustrations of this manual are from electro-
types kindly loaned the author by the Bausch & Lomb Optical Company,
of Rochester, N. Y. Students and others desiring to purchase micro-
scopes and microscopic supplies will find this firm courteous in its deal-
ing's. The goods sent out by this house are reasonable in price and first-
class in quality.

16 MICROSCOPY.

CHAPTER II.

MICROSCOPIC TECHNIQUE.
I. THE HISTORY OF THE SLIDE.

The history of a slide from the crude tissue to the finished mount
includes the following processes : Fixing, hardening, infiltrating, em-
bedding, sectioning, fixation, staining, dehydrating, clearing,
mounting, labeling.

1. Fixing.— This process consists in so killing the cells as to pre-
serve them in their natural form and structure. The reagents com-
monly used for this purpose are alcohol, corrosive sublimate, chromic
acid, Perenyi's fluid, etc. To fix tissues in absolute alcohol, they
should be allowed to remain from one to six hours, according to the
character of the specimen. Objects are left in Perenyi's fluid from
three to twelve hours and then transferred to seventy per cent al-
cohol. Specimens hardened in corrosive sublimate solution should
be removed in one to three hours, according to size.
To fix tissue in chromic acid requires from a few days
to a few weeks. After fixing in the last reagent, the tissue should
be thoroughly washed with water and then run through increasing
strengths of alcohol in the dark. Picro-sulphuric Acid, Erlicki's
Fluid, Muller's Fluid, and Flemming's Solution are also commonly
used for this purpose.

2. Hardening.— This consists in dehydrating the tissues so as to
make them rigid and suited for sectioning with the microtome. For
this purpose alcohol is commonly used. The tissue should be run
through increasing strengths — seventy per cent, eighty per cent,
ninety per cent, ninety-five per cent, and absolute alcohol. Objects
should not be allowed to remain long in absolute alcohol (from one
to five hours), as this renders the tissue brittle and causes it to crum-
ble under the knife of the microtome. The objects may remain in
the other strengths of alcohol about twenty-four hours for each.

3. Infiltrating. — This process consists in removing the hardening
agent and filling up the pores of the tissue with an embedding me-

MICROSCOPIC TECHNIQUE. 17

drum. As soon as the object is removed from absolute alcohol it
should be thoroughly dried with blotting paper. If it is desired to
embed with paraffin, the specimen should be placed in xylol, chloro-
form, turpentine, or cedar oil for at least twelve hours, and then
transferred to a solution of paraffin and xylol, allowing it to remain
twelve to twenty-four hours. It may now be transferred to melted
paraffin, which should be kept as little above the melting point as
possible. After remaining until it becomes thoroughly saturated
with the paraffin, which usually requires from twelve to twenty-
four hours, it may then be embedded. To infiltrate with celloidin,
two solutions are necessary, a thin and a thick. The celloidin is dis-
solved in equal parts of absolute alcohol and ether. To make the
thin solution, use five grams of celloidin in 100 cc. of the mixture.
The second solution should have the consistency of thick sirup. The
dehydrated tissue is placed in a mixture of equal parts of absolute
alcoHol and ether from twelve to forty-eight hours, then in the thin
solution for about the same period. It may remain in the thick
solution twenty-four hours, or longer if desired. It is then ready for
embedding.

4. Embedding in paraffin — Embedding L's or paper boxes may be
used. To accomplish this process, the following method may be
pursued: Place upon a pane of glass a clean piece of paper. Ar-
range the embedding L's so as to form a receptacle of the required
size. Pour into this a small quantity of melted paraffin. Now ar-
range the tissue in the position desired and fill the receptacle with
paraffin. As soon as the paraffin becomes sufficiently hardened the
embedding L's may be set in a vessel containing ice-cold water. Care
should be taken that the water does not run over the top of the
paraffin.

To Embed with Celloidin. — A cork or block of wood which has
been soaked in equal parts of absolute alcohol and ether may be
used. Place upon the cork or block a small quantity of thick cel-
loidin.. Then place in position the piece of tissue and cover it with
the celloidin, adding a little at a time, layer after layer as each
hardens, until the tissue is completely embedded. The whole may
now be transferred to chloroform for one or two hours, and then
to seventy-five per cent alcohol, where it may be left indefinitely.
2

18 MICROSCOPY.

5, Sectioning. — This consists in cutting thin sections of the ob-
ject to be examined. It is accomplished by the use of a razor, or mi-
crotome knife, which may be used free-hand or with a microtome.
To cut paraffin sections, first pare the block to the right size and then
fasten it in the clamp of the microtome. The paraffin should be
kept at the right temperature. This may be accomplished by using
cold or hot water, applying it with a camelVhair brush, or with the
heat of the hand or a flame. The knife should be drawn at a slight
angle. If sections curl, they may be placed upon the surface of
moderately warm water to flatten them. Curling may be prevented
by holding the sections in place with a cameFs-hair brush as they
are cut.

Celloidin sections are cut in the same way, with the exception
that the knife and celloidin block must be kept constantly flooded
with seventy-five per cent alcohol. The sections when cut may be
removed to a vessel containing seventy-five per cent alcohol, and
there kept indefinitely.

6. Fixation. — This consists in attaching sections to the slide.
Paraffin sections may be affixed with collodion mixture, or with egg-
albumen and glycerine. To affix with collodion, make a thin layer
with camelVhair brush upon the slide. Then apply the section,
flattening it out with finger or brush; now apply the heat of a spirit
or Bunsen flame until the paraffin melts, being careful to avoid
excessive heating, such as would injure the tissue. To affix with
egg-albumen and glycerine, a thin coating is made with a camel's-
hair brush, and the section is then transferred to the center of the
slide, care being taken to flatten it out with finger or brush. Heat
is then applied to coagulate the albumen. To avoid overheating,
the slide should be frequently applied to the surface of the hand.
When the paraffin becomes thoroughly melted the section is usually
properly affixed.

If desired to affix celloidin sections, a drop of ether may be ap-
plied to each section after placing it in the desired position, or they
may be affixed with the collodion and clove-oil mixture in the fol-
lowing manner : Apply a thin layer of collodion mixture to center of
slide ; when the collodion is dry apply the section, together with the
thin piece of paper upon which it has been placed, and press upon

MICROSCOPIC TECHNIQUE. 19

the whole with a dry blotting paper. The section will now adhere
and the paper may be removed. Now cover the section with a thin
layer of collodion mixture, and it will be thoroughly affixed.

Centering. — The process of fixation should also include the cen-
tering of the section. This may readily be accomplished by means
of a diagram of the slide, which may be drawn upon the under sur-
face of the cover of a mailing box. See laboratory exercise No. 3.

7. Staining. — This process consists in tinting the structures of the
section with certain stains, so as to produce a differentiation of the
different elements and render them more readily studied. It de-
pends upon the principle that certain structures have an affinity for
certain stains, but not for others. For example, a stain that will
affect the protoplasm and nucleus may have no effect upon the cell-
wall. A stain that will affect certain cells may have no effect upon
others. Haematoxylin will stain the leucocytes, but not the red cor-
puscles. Eosin will stain the red corpuscles, but not the white.
Staining should always be preceded by certain processes so as to
prepare the tissue to receive it. First, if a paraffin section is to be
stained, the paraffin must be removed. This is accomplished by
immersing it in xylol, turpentine, chloroform, or benzole. These
reagents dissolve out the paraffin. The xylol, etc., may then be re*
moved by applying alcohol. Should an aqueous solution of any
stain be used, the section should be washed with water before ap-
plying the stain, and followed with the same. If the stain be alco-
holic, its application should be preceded and followed by alcohol of
the same strength. The different staining methods are given on
page 23.

8. Dehydrating. — This consists in the removal of water from the
specimen, water being generally the enemy of the histologist. It
is accomplished by running the section through increasing strengths
of alcohol, using first an alcohol of the same strength as the stain-
ing solution. The object of this is to prevent the precipitation of the
stain, by which the preparation becomes filled with dark granular
masses.

9. Clearing.— This consists in the removal of the alcohol so as to
prepare the sections for balsam and in so clearing up the section as
to render it transparent. By closely observing the change in color

20 MICROSCOPY.

or by placing the finger nail beneath the section, the student can de-
termine whether the process is complete. The reagents commonly
used for clearing purposes are creosote, cedar oil, xylol, benzole,
clove oil, and aniline oil.

10. Mounting consists in permanently attaching the cover-
glass for the protection of the specimen. Balsam and glycerine-
jelly are generally used for this purpose. For laboratory work the
balsam method will be found the most convenient. Place upon the
cover-glass, while holding it between the fingers, a drop of balsam,
and then (balsam down) let it fall gently upon the section. After
centering the cover-glass, apply gentle pressure by means of a dis-
secting needle, so as to force the balsam out to the edges of the glass.
Should too much balsam be used, it may be removed (when thor-
oughly dried) with a pen-knife. This method will be found more
satisfactory than to undertake its removal with cloth or brush by
means of xylol. The safest plan is to use just enough balsam, no
more, no less.

11, Labeling. — Two labels should be used, one on each end of the
slide, and they should be so applied that the edges of the labels will
be the same distance from the edges of the slide. The left hand label
should indicate the number of the preparation, the staining fluid,
the mounting medium, the date, and the name of the student. The
right hand label should indicate the kind of tissue, the character of
the section (whether transverse, longitudinal, vertical, or oblique),
the condition of the specimen (whether normal or abnormal), and
the animal from which it has been obtained. After labeling, the
preparation should be placed in the slide-box in a horizontal posi-
tion, with the cover-glass up, and kept in that position until the bal-
sam hardens.

II. SPECIAL TREATMENT OF TISSUES AND ORGANS.

The structures required for microscopic work may be obtained
from some animal, such as the cat, rabbit, or guinea pig. Should a
cat be used, it may be killed by placing it under an inverted bowl
(resting upon a heavy sheet of paper upon a table or floor), and then
inserting a sponge saturated with chloroform. In twenty minutes
the animal will be dead and ready for injection.

Injecting. — To inject the animal, the following process may be

MICROSCOPIC TECHNIQUE. 21

pursued: Sever the costal cartilages on each side of the sternum;
lift up the sternum and bend it forward so as to expose the heart.
Make a slit into the right auricle to allow the escape of the blood.
Snip off the end of the heart and slit open the left ventricle- Insert
the canula of the injecting syringe into the aorta, carefully tying the
same upon the end of the canula. Now, having filled the syringe
with normal saline solution at body temperature and having filled
the canula with the same, using pipette, attach the two, and with
a gentle pressure force the liquid through the system until the ar-
teries and veins have been thoroughly relieved of blood. Eepeat the
same process, using Carter's Carmine Mass. By observing the lips
and other structures it can be determined when the circulatory sys-
tem is filled with the injecting fluid. ISTow, make a ligature around
the aorta, just beyond the canula, and the syringe can be removed.
In fifteen minutes the tissues can be cut up into small blocks (these
blocks should be in the form of cubes or rectangles from 1 cc. to 2
cc. in size), and placed in the fixing fluids.

Epithelium. — For purposes of study epithelium may be obtained
from the casts of a frog or newt, from the scrapings of the human
lip, from the throat of a frog, and the scrapings of the trachea of a
pig. This material may be readily obtained by macerating the ob-
ject in weak alcohol. Keep the specimens in eighty per cent al-
cohol, and use when required.

Cartilage. — Fix in absolute alcohol; harden with increasing
strengths of alcohol, and embed in paraffin. Stain with carmine.

Mucous Tissue. — Fix small pieces of the umbilical cord with ab-
solute alcohol, harden with alcohol, embed in celloidin, and stain
with hsematoxylin.

Bones and Teeth. — Fix in ninety-five per cent alcohol three days;
decalcify in a saturated aqueous solution of picric acid or in a ten
per cent solution of nitric acid. This process will require from five
to ten days. When the bone or tooth is thoroughly softened, trans-
fer to ninety-five per cent alcohol, changing in three days to fresh
alcohol. Embed in celloidin. Specimens embedded in paraffin
should not be overheated.

Muscle. — Fix in absolute alcohol; harden with increasing
strengths of alcohol ; embed in paraffin ; stain with lithium carmine.

22 MICROSCOPY.

The muscle of a salamander will be found excellent for demonstrat-
ing the structure of the fibers.

Brain and Spinal Cord. — Fix and harden in Muller's fluid or
Erlicki's fluid, two weeks for the former and fifteen days for the
latter. Wash thoroughly in water before embedding, which may be
done in paraffin.

Heart. — Fix in absolute alcohol; harden with alcohols; embed in
paraffin; stain with haematoxylin.

Blood Vessels. — Fix and harden with alcohol; embed in paraffin
or celloidin; and stain with lithium carmine or haematoxylin and
eosin.

Lymphatic Glands. — Fix and harden1 with alcohol ; embed in cel-
loidin ; and stain with haematoxylin and eosin.

Skin. — Fix and harden with alcohol; embed in paraffin; and
stain with haematoxylin and eosin.

The Spleen. — Fix and harden with alcohol; embed in paraffin;
stain with haematoxylin and eosin.

(Esophagus. — Fix with corrosive subliniate or Perenyi's fluid;
harden with alcohol ; embed in paraffin ; and stain with haematoxy-
lin and eosin.

Stomach. — Fix with corrosive sublimate; harden with alcohol;
embed with paraffin or celloidin ; stain with haematoxylin.

Intestine. — Fix with corrosive sublimate; harden with alcohol;
embed in celloidin ; stain with hgematoxylin and eosin.

Tongue. — Fix with absolute alcohol ; harden with alcohols ; embed
in paraffin : and stain with haematoxylin and eosin.

Trachea. — After filling the trachea and lungs with a two-tenths
per cent solution of chromic acid, suspend them in a large volume of
the same for two days ; then cut into small pieces and place in two-
tenths per cent of chromic acid for two or three weeks ; wash thor-
oughly with water; embed in celloidin; and stain with haematoxylin.

Lungs. — These may be treated as the trachea; embed in par-
affin or celloidin; and stain with lithium carmine or haematoxylin
and eosin.

Liver. — Fix with corrosive sublimate, one per cent solution, twen-
ty-four hours; harden with alcohol; embed in paraffin: and stain
with hsematoxvlin and eosin.

MICROSCOPIC TECHNIQUE. 23

Kidney. — Fix and harden with alcohol; embed with paraffin; and
stain with haematoxylin and eosin.

Ovary. — Fix and harden with alcohol; embed in paraffin; and
stain with haematoxylin and eosin. The Fallopian tube may be
treated in the same way.

Uterus. — Fix and harden with alcohol; embed in paraffin; and
stain with haematoxylin and eosin.

Testis. — Fix with corrosive sublimate, and harden with alcohol;
embed in paraffin ; and stain with lithium carmine.

Eye. — Cut across the eye so as to partly divide it into an anterior
and posterior half; suspend in 150 cc. of chromic acid (0.25 per
cent) for twenty-four hours; sever the halves and renew the fluid;
after several days' wash in water, and harden in alcohol in the dark ;
embed in paraffin ; and stain with haematoxylin and eosin.

Pancreas. — Fix with Flemming's solution, twenty-four hours;
harden with alcohol ; stain with lithium carmine ; embedding may be
done in paraffin.

III. STAINING METHODS.

Sections to be stained may be fresh specimens or those that have
been cut from embedded tissue. They may be free — that is, unat-
tached to the slide, or affixed. The following schemes for staining
are intended to be sufficiently comprehensive to include all of these
conditions :

No, 1. METHOD FOR STAINING FRESH VEGETABLE
SECTIONS.

( 1 ) Apply section to slide and add rosanilin violet, one to five min-
utes.

(2) Wash in water to remove excess of stain.

(3) Dry with blotting paper and add glycerine to dehydrate.

(4) Remove excess of glycerine and add glycerine again to thor-
oughly dehydrate.

(5) Wipe off excess of glycerine and add xylol twice.

(6) Apply to cover-glass a drop or two of xylol-balsam, and, hav-
ing wiped off the excess of xylol from the slide, drop it gently (bal-
sam down) upon the section. Then apply gentle pressure with dis-
secting needle to spread out the balsam.

24: MICROSCOPY.

(7) Label and keep in a horizontal position until the balsam is
hardened.

Vegetable Sections. — To stain paraffin or celloidin sections of
plant structures, the methods are practically the same as those given
below for animal objects.

Methods for Animal Sections.

No. 2. CARMINE METHOD FOR FREE SECTIONS.

(1) Apply section to slide and wash with thirty-five per cent al-
cohol.

(2) Add lithium carmine sufficient to cover section., one to five
minutes.

(3) If necessary, remove excess of stain with acid alcohol, five
to ten seconds.

(4) Dehydrate with increasing strengths of alcohol — thirty-five
per cent, seventy-five per cent, ninety-five per cent, and absolute.

(5) Wipe off excess of alcohol, and when section is partly dry
add creosote to clear up, five to ten minutes.

(6) Wipe off excess of creosote and mount with balsam.

(7) Center cover-glass and apply pressure to spread out the bal-
sam.

(8) Label and lay aside in horizontal position, cover-glass up,
until the balsam hardens.

No. 3. CARMINE METHOD WITH AFFIXED PARAFFIN

SECTIONS.

(1) Apply to the center of the slide a thin layer of collodion-
clove-oil mixture.

(2) Center and attach the section, applying the heat of a spirit
or Bunsen flame.

(3) Immerse in xylol two minutes and in turpentine ten min-
utes to remove paraffin. Sections immersed in turpentine alone
should remain twenty minutes.

(4) Wash with alcohol, decreasing strengths, using thirty-five
per cent alcohol last.

MICROSCOPIC TECHNIQUE. 25

(5) Apply lithium carmine, one to ten minutes.

(6) Remove excess of stain with acid alcohol.

(7) Dehydrate with alcohol, increasing strengths.

(8) Dry and clear up with creosote, five to ten minutes.

(9) Wipe off excess of creosote and mount in balsam.

(10) Center cover-glass.

(11) Label and lay aside in horizontal position until balsam
hardens.

No. 4. CARMINE METHOD FOR AFFIXED CELLOIDIN
SECTIONS.

(1) Center section and affix with collodion mixture.

(2) Stain with lithium carmine, one to five minutes.

(3) Remove excess of stain with acid alcohol, five to ten seconds.

(4) Apply seventy per cent alcohol.

(5) Apply eighty per cent alcohol.

(6) Apply ninety-five per cent alcohol a few seconds.

(7) Clear up with creosote.

(8) Remove excess of creosote with blotting paper.

(9) Mount with balsam and center cover-glass.

(10) Label and lay aside in a horizontal position.

No. 5. H^IMATOXYLIN METHOD FOR FREE SECTIONS.

(1) With section on slide, apply alcohol of the same strength as
staining solution. ,

(2) Stain with diluted ha3matoxylin, one to ten minutes.

(3) Remove excess of stain with thirty-five per cent alcohol.

(4) Dehydrate with alcohols, increasing strengths.

(5) Clear up with creosote or cedar oil.

(6) Center section and apply balsam and cover-glass.

(7) Center cover-glass.

(8) Label and lay aside in horizontal position until balsam
hardens.

No. 6. KffiMATOXYLIN METHOD FOR AFFIXED PARAF-
FIN SECTIONS.

(1) Apply to slide a thin layer of egg-albumen and glycerine.

26 MICROSCOPY.

(2) Center section and flatten it by gently touching with end of
finger.

(3) Apply heat of flame until paraffin melts (sections that have
been flattened upon water should be heated much longer than
others).

(4) Eemove paraffin with xylol or turpentine.

(5) Eemove xylol, etc., with alcohol, decreasing strengths.

(6) Stain with diluted haematoxylin, one to ten minutes.

(7) Remove excess of stain with thirty-five per cent alcohol.

(8) Dehydrate with alcohol.

(9) Clear up with creosote, five to ten minutes.

(10) Wipe off excess of creosote and mount with balsam.

(11) Center cover-glass.

(12) Label and keep in horizontal position until balsam hardens.

No. 7. HJEMATOXYLIN METHOD FOE AFFIXED CELLOIDIN

SECTIONS,

(1) Center section and affix with collodion mixture.

(2) Stain with diluted hgematoxylin, one to ten minutes.

(3) Remove excess of stain with acid alcohol.

(4) Apply seventy per cent alcohol.

(5) Apply eighty per cent alcohol.

(6) Apply ninety-five per cent alcohol a few seconds.

(7) Clear up with creosote, five to ten minutes.

(8) Remove excess of creosote with blotting paper.

(9) Mount with balsam and center cover-glass.

(10) Label and lay aside in a horizontal position until balsam
is hardened.

No. 8. KEMATOXYLIN-EOSIN METHOD.

( 1 ) If desired, affix section to slide with egg-albumen and glyc-
erine or collodion and clove-oil.

(2) If a paraffin section, remove paraffin with xylol or turpen-
tine or both; remove xylol, etc., with alcohol.

(3) Apply thirty-five per cent alcohol.

(4) Stain with diluted hsematoxylin, one to five minutes.

(5) Apply thirty-five per cent alcohol to remove excess of stain.

MICROSCOPIC TECHNIQUE. 27

(6) Stain with alcoholic eosin about five minutes.
(?') Apply ninety-five per cent alcohol to remove excess of stain
and dehydrate.

(8) Clear up with creosote.

(9) Eemove excess of creosote and mount with balsam.

(10) Center cover-glass and label.

(11) Lay aside in horizontal position until balsam hardens.

Staining Unicellular Organisms.

It is often desirable to examine material without staining. This
is accomplished by placing upon the glass slip a drop of the ma-
terial to be examined and applying cover-glass. A hair placed un-
der the cover-glass will prevent the object from being crushed and
allow of free motion in the case of living organisms. Should it
be desired to stain such preparations, two methods may be pursued,
irrigation and cover-glass staining.

No. 9. IRRIGATION AND STAINING MICRO-ORGANISMS.

(1) Place upon the slide a drop of material to be studied.

(2) Apply cover-glass.

(3) At the edge of the cover-glass, by means of a pipette, place
a drop or two of the reagent or stain.

(4) By means of a triangular piece of blotting paper applied at
the opposite edge of the cover-glass, absorb the moisture from the
preparation, thus drawing under the stain.

No. 10. COVER-GLASS PREPARATIONS.

(1) Make a thin spread of the substance to be examined upon a
sterilized cover-glass.

(2) Using a Cornet forceps, dry the preparation by holding it
between the fingers above a flame.

(3) When dry pass the cover-glass three times through a flame,
keeping the preparation up.

(4) Apply stain.

(5) Wash in distilled water by dipping the cover-glass in the
water two or three times.

(6) Examine as a water mount or, if desired, dry and mount
in balsam.

28 MICROSCOPY.

(7) Label and lay aside in a horizontal position until balsam
hardens.

Note. — The above method may be used for all simple staining.
Special methods, however, are often used, and they will be given
as required.

Laboratory Exercise No. 3. — Centering and labeling. Upon the under
side of your box-cover make an outline of a slide. The pencil should
have a needle point. Connect opposite angles and place over the inter-
section of the lines a cover-glass. Be sure that the center of the cover-
glass coincides with the center of the diagram. Now, carefully make
an outline of the cover-glass. This outline may be used for centering
both the sections and the cover-glass. Make a drawing of this outline
on page 29, also a drawing of a slide with labels and cover-glass in situ.
Fill in the forms of labels in second diagram, using the following data:
A transverse section of the muscle of a normal cat was stained with
lithium carmine and mounted in balsam on October 1, 1891, by John
Smith.

Drawings. For this work the student should provide himself with a
No. 5 or a No. 6 H Faber pencil, a small rule or triangle and a sheet of
thin blotting paper. The pencil should be kept sharpened to a needle
point. The majority of students will say: I cannot draw. An honest
and faithful effort will often produce gratifying results. Let every
line mean something. Be scrupulously neat in all your work. Remem-
ber that this work will furnish a better exhibit of character and abil-
ity than any other task of the laboratory.

Abbreviations. The following abbreviations are employed in this
text:

Transverse section — T. S.
Longitudinal section — L. S.
Vertical section — V. S.
Low power — L. P.
High power — H. P.
Cubic centimeter — c. c.
Micro-millimeter — /z.
Millimeter — mm.
Gram — g.

MICROSCOPIC TECHNIQUE.

Diagram of Slide and Cover Glass.

Diagram for centering: (a) Slide; (b) Cover Glass; (c) Center.

Labels in situ.

Labeling: (a) Label properly filled out for reagents, etc. ; (b) Label descriptive
of section.

30 MICROSCOPY.

CHAPTEE III.
REAGENTS AND STAINS.

In preparing the following reagents it is well to remember that
the weight of a cubic centimeter of water is one gram, and that a
liter contains 1,000 cubic centimeters. The formulae that are given
are those most commonly used and are briefly stated :

NORMAL FLUIDS.

Distilled water.— A supply of distilled water should be constantly
at hand for the preparation of the reagents and stains.

Normal saline. — This is prepared by dissolving one part, by
weight, of sodium chloride in 150 parts of distilled water.

MACERATING FLUIDS,

Dilute alcohol. — This may be prepared by mixing one part of
ninety-live per cent alcohol with two parts of distilled water. Other
fluids used for this purpose are solutions of potassium bi-chromate,
two per cent, and caustic potash, twenty-five per cent.

DECALCIFYING FLUIDS.

Picric acid. — Make a saturated aqueous solution of picric acid.
This is an excellent fluid for decalcifying bones, serving at the same
time as a staining reagent. Crystals should be added from time to
time, so that some undissolved crystals will always remain in the
bottom of the vessel.

Nitric acid.— Use a ten per cent volumetric solution in water.
Decalcification occurs in five to ten days.

FIXING REAGENTS.

Absolute alcohol. — Specimens should remain in this reagent from
one to six hours, according to size.

Perenyi's fluid —

Nitric acid (ten per cent) 40 cc.

Chromic acid (0.5 per cent) 30 cc.

Alcohol . . . 30 cc.

REAGENTS AND STAINS. 31

A good reagent for embryos and adult tissues. Time, three to
twelve hours ; dehydrate with alcohol.

Erlicki's fluid —

Potassium bi-chromate 2.5 grams.

Cupric sulphate 0.5 grams.

Water 100 cc.

A good reagent for general use, for embryos and nervous tissues.
Time, ten to fifteen days ; dehydrate with alcohol.

Corrosive sublimate —

Aqueous Solution —

Corrosive sublimate 1 gram.

Water 95 cc.

Alcoholic Solution —

Corrosive sublimate 1 gram.

Alcohol (ninety-five per cent) ...... .99 cc.

Used for general purposes, and specially for alimentary tract.
Time, twenty-four hours, hardening in alcohol, to which a few
crystals of iodine have been added.

Chromic acid. — Use a 0.5 per cent solution, dehydrating with
alcohol in the dark.

Muller's fluid-
Potassium bi-chromate 25 grams.

Sodium sulphate 10 grams.

Water 1,000 cc.

Pulverize the solids before adding water, and use a piece of cam-
phor in the solution to prevent the formation of fungi. Good for
general use and especially valuable for central nervous system. Re-
quires from two to six weeks. Wash in water for several days, and
dehydrate with alcohol.

Flemming's fluid —

Chromic acid (one per cent solution) ... .46 cc.

Osmic acid (two per cent solution) ...... 12 cc.

Glacial acetic acid.. . 3 cc.

32 MICROSCOPY.

Especially valuable for delicate tissue. Time, two to twenty-four
hours ; dehydrate with alcohol.

HARDENING REAGENTS.

Muller's fluid, corrosive sublimate solution, chromic acid, and
others of the reagents named above may be used for hardening pur-
poses. For general use, alcohol will be found invaluable. The tis-
sue should be passed through increasing strengths of alcohol, seven-
ty per cent, eighty per cent, ninety per cent, ninety-five per cent,
and absolute. It should be allowed to remain twenty-four hours in
each, except that one to six hours will suffice for absolute alcohol.
Ethyl alcohol should be used, or, in lieu of this, methyl alcohol makes
a good substitute. To prepare absolute alcohol, dehydrated copper
sulphate may be added to the ethyl or methyl alcohol. This will ab-
sorb the water present.

EMBEDDING MEDIA.

Paraffin and celloidin are extensively used for embedding tissue.
The process for each has been fully explained in the chapter on
" Microscopic Technique."

FIXATIVES.

Collodion and clove oil mixture. — Mix one part of collodion with
three parts of clove-oil.

Egg-albumen and glycerine. — Filter the whites of several eggs
and add to the filtrate an equal volume of glycerine. To the mix-
ture add a few drops of carbolic acid or a small piece of thymol to
prevent putrefaction.

PARAFFIN SOLVENTS.

Xylol, turpentine, chloroform, and benzole are commonly used
to remove paraffin from sections. A good plan is to immerse the
slide containing the section for a few moments in xylol, and then
transfer to turpentine for ten minutes.

STAINING SOLUTIONS.

The following staining preparations are those most frequently
used, and will be found adequate to the work required by this text.
Should others be needed, the formulae can be obtained from more
advanced works.

REAGENTS AND STAINS. 33

Hanstem's rosanilin violet —

Methyl violet 1 gram.

Fuchsia 1 gram.

Distilled water 100 cc.

Note. — This is a valuable stain for vegetable sections. It should
be diluted for use as desired.

Lithium carmine —

Carmine 2.5 grams.

Lithium carbonate (saturated solu-
tion) 100 cc.

The carmine should be dissolved in cold solution. Sections stain
rapidly, and should be decolorized with acid alcohol.

Dalafield's haematoxylin —

1. Hasmatoxylin 1 gram.

2. Absolute alcohol 6 cc.

3. Ammonia alum (saturated sol.)... 100 cc.

4. Glycerine 25 cc.

5. Methyl alcohol 25 cc.

Process.— Dissolve (1) in (2) ; add this solution to (3) ; expose
to air and light for a week; filter and add (4) and (5) ; allow it to
stand for a long time exposed to air and light.

Eosin —

Alcoholic Eosin for Sections. — Make a saturated alcoholic solu-
tion. This is used as a ground stain in connection with haematoxy-
lin; also as a blood stain.

Magenta for hlood, etc. —

Magenta •. 1 gram.

Alcohol (eighty-five per cent) 50 cc.

Water 150 cc.

Glycerine 200 cc.

Methylene blue for hlood —
Make a saturated aqueous solution.

34 MICROSCOPY.

Carter's carmine mass for injecting —

Carmine 3 grams.

Strong ammonia 6 cc.

Glacial acetic acid 6 cc.

Coignet's French gelatin 7 grams.

Water 80 cc.

Process. — " Place the finely cut gelatin in 50 cc. of water for five
hours ; dissolve the carmine in a mortar with a little water, and add
the ammonia; let stand for two hours and then pour into a bottle,
rinsing the mortar with the remainder of water; place the gelatin
and water on a water-bath until the gelatin melts. To the carmine
fluid add the acetic acid, a few drops at a time (rinsing mortar thor-
oughly) until the fluid becomes crimson. To the melted gelatin add
the crimson carmine, little by little, with continual stirring. Keep
in a cool place with surface covered with methylated spirit. When
wanted for use, dissolve on water-bath and filter through flannel
wrung out of hot water." (Fearnley's Method.)

CLEARING AGENTS.

Those commonly used are cedar oil, creosote, clove-oil, xylol, and
aniline oil. Clove-oil cannot be used with celloidin sections.

MOUNTING MEDIA.

Glycerine jelly and Canada balsam are commonly used for mount-
ing purposes. For the laboratory balsam will be found a satisfactory
medium. Should xylol be used for clearing, the balsam should be
dissolved in xylol. Chloroform balsam may be used in sections cleared
with chloroform.

For the formulae of reagents and stains required for work in bac-
teriology and urinalysis, the reader is referred to the chapters in
which is discussed the micro-technique of these subjects.

NORMAL HISTOLOGY. 35

PART II.

NORMAL HISTOLOGY.

This brief discussion of the facts and principles of normal histol-
ogy is applied chiefly to animal structures, with special reference to
the human body. The animal body is composed of organs. Organs
are constituted of tissues, and tissues consist of cells and intercellu-
lar substances. The histologist has to do chiefly with cells. There-
lore, a thorough knowledge of the nature, structure, and functions
of the cell is necessary to an adequate comprehension of this sub-
ject.

CHAPTEE IV.

THE CELL.

The cell is a mass of protoplasm containing a nucleus and gen-
erally enclosed in a thin membrane called the cell-wall. The nu
cleus is believed always to be present, though there are some in-
stances in which no nucleus has yet been discovered. The cell-wall
is not an essential part, and is often absent ; example, leucocytes and
amcebaB.

Miller's Paraffin Bath..

Bausch & Lomb Optical Co., Rochester, N. Y.

NORMAL HISTOLOGY.

OUTLINE OF THE CELL.

Structure

f Cell wall.

Protoplasm

Centrospheres.
Nucleus j

Vacuoles •!

/

f C h r o m a t o -

Nucleolus.
Chromatin.

Water vacuoles.
Food vacuoles.

Chloroplasts.

Cell contents... -

phores ....... < Leucoplasts.

salts. I Chromoplasts.

Volatile oils.

Alkaloids.

Ferments.

Kinds of cells.. | Sr

Support.
Reservoirs of
nutriment.

Cell multiplica-

Functions

-•

• - < Free cell forma-
tion.
[ Karyokinesis.

Asexual •{

' Normal fission.
Budding1.
Free cell forma-
tion.

Reproduction of
individuals. . . -j

1 Sexual

Rejuvenescence
Spore forma-
tion.

1 Conjugation.
Parthenogen-

,,.,,. ( Anabolism.
, Metabolism . . . . | Katabolism.

esis.
Fertilization.

THE CELL. 37

STRUCTURE OF THE CELL.

The parts of a cell are the cell-wall, protoplasm, controspheres,
nucleus, and vacuoles.

(1) The cell- wall. — This is the thin membrane inclosing the
protoplasm. With animals, the cell-wall consists of protein; with
plants, it is composed of cellulose. Protein is a compound possess-
ing the same elements as starch, but with nitrogen added. Cellu-
lose, C6H10O6, is an isomeric form of starch, having the same com-
position, but differing from it in being homogeneous in structure,
not granular, and in being less easily dissolved and less readily con-
verted into dextrin.

(2) Protoplasm, — This is the living substance of the cell, the or-
ganic basis of life. It contains carbon, hydrogen, oxygen, nitrogen,
sulphur, and sometimes phosphorus, iron, and other elements. No
chemical formula can be given for its composition, but it consists
of unstable, constantly changing molecules. When dead, its chem-
ical nature is changed, and it consists of protein, f carbo-hydrates,
water, and mineral salts. Of these, protein alone possesses nitrogen.
Living protoplasm is irritable, unstable, deoxidizing ; has the power
to eliminate carbon di-oxide, and can reproduce itself, and, by as-
similation, manufacture the innumerable products characteristic of
plants and animals. The protoplasm of adjacent cells is sometimes
connected by delicate threads, which pass through their walls.
Protoplasm is a viscid, transparent substance resembling egg-al-
bumen. It is never completely fluid. It is not homogeneous, but
somewhat complicated in structure. It consists of two parts, the
cytoplasm and the nucleoplasm. The cytoplasm constitutes the
bulk of the protoplasm in the cell. It consists of an outer, dense
film, the ectoplasm, and an inner, semi-liquid portion, the ento*
plasm, containing a fibrous sponge-work holding in its threads the
microsomes, centrosplieres, and nucleus. Microsomes are minute
spherical masses supposed to contain nutrition for the growing cell,
but their real functions are not well understood. The neucleoplasm
enters into the structure of the nucleus and nucleolus.

(3) The centrospheres. --These are minute bodies associated
with the nucleus and scarcely larger than the microsomes. Each
centrosphere consists of an outer, hyaline film of cytoplasm, within

38 NORMAL HISTOLOGY.

which is a fibrous sponge-work containing a dense body, the centro-
some. The centrosphere multiplies by division, and thus initiates
the complicated processes by which one cell develops into two.

(4) The nucleus. — This is the larger, rounded, dense portion of
protoplasm. Its protoplasm is styled nucleoplasm. Its structure is
similar to that of the cytoplasm, consisting of an outer, dense ecto-
sarc and an inner sponge- work containing one or more nucleoli and
the chromatin, a substance very susceptible to stains. The nucleus
and centrospheres constitute the centers of vitality, the sources of
growth and vital phenomena.

(5) The valcuole. — This is the cell cavity and contains a watery
fluid or food masses for the nourishment of the cell. There may
be several vacuoles in a cell. In very young cells there is no vacuole,
the protoplasm filling the entire space. Old cells lose their proto-
plasm and may be empty or filled with the products of assimilation.

With plant cells the cytoplasm often forms a layer within the
cell-wall, called the primordial-utricle.

CELL CONTENTS.

Besides the structures above named, the cell contains the chromat-
ophores, starch, mineral salts, proteids, fat, volatile oils, alkaloids,
ferments, and pigments.

(1) The chromatophores are the color bearers. Among plants
there are three kinds — the chloroplasts, leucoplasts, and chromo-
plasts. The chloroplasts contain the green coloring matter, called
chlorophyl. Some animals contain chlorophyl, as, for example, the
Green Euglaena. Chlorophyl has the power to decompose carbon-
di-oxide. Its chemical composition is unknown. It is soluble in
alcohol. The chromoplasts are the proteid products which contain
the coloring matter that gives the color to flowers and fruits. The
leucoplasts, or amyloplasts, are corpuscles which engage in the
manufacture of starch granules. They are found in portions of a
plant removed from light.

(2) Starch, C6H10O5, is found in the cell and is produced
within the chloroplasts by the union of carbon (obtained from C02)

and water. Reaction :

C02=C+20

6C + 5ff20=C6H1005

THE CELL. 39

This process is carried forward under the influence of sunlight.
Thus the plant stores up the energy of the sunbeam in complex
molecules to be utilized by man and other animals.

Other carbo-hydrates often occurring in a cell are dextrin, glu-
cose, cane sugar, etc.

(3) Mineral salts. — These often occur in a cell in crystalline
form. Crystals in plant cells are called raphides.

(4) Proteids. — These occur in plant cells as crystalloids and
aleurone grains. Crystalloids are protoplasmic bodies, crystalline in
form, but not in character. Aleurone grains are proteid granules
generally associated with crystalloids.

(5) Fat occurs in the cell as globules. It contains the same ele-
ments as starch, but the hydrogen and oxygen are not in the pro-
portion of water. It serves as a reserve food supply.

(6) The volatile oils, such as turpentine, bergamot, and asa-
fetida, occur especially in plant cells, and give to plants their per-
fumes.

(7) The alkaloids are organic bases bearing nitrogen. The solid
alkaloids contain oxygen, whereas those that are liquid and volatile
do not. When reacting with acids they form soluble salts. They
furnish many powerful poisons and useful medicines, and are char-
acteristic of plants.

(8) The ferments are nitrogenous compounds which have the
power to bring about important chemical changes in organic sub-
stances.

KINDS OF CELLS.

The important kinds of plant cells are parenchymatous and
prosenchymatous cells, traclieids, and vessels. Some of the varieties
of animal cells are leucocytes, epithelial cells, cartilage cells, bone
corpuscles, marrow cells, lymphoid cells, etc.

FUNCTIONS OF CELLS.

The cell is the laboratory of the body in which are manufactured
all those complex products which enter into its structure. The
processes by which these products are elaborated are andbolism
(building up) and Jcatabolism (breaking down). The two proc-

40 NORMAL HISTOLOGY.

esses together constitute metabolism, the former being constructive
metabolism and the latter destructive metabolism.

The cell, by the rigidity of its walls or its contents, gives support
to the structures of the body.

The cell often serves as a reservoir for the products of assimila-
tion.

The cell is the agent by which new cells are formed and by which
the plant or animal is reproduced.

The method by which new cells are formed is a process of divi-
sion. There are four forms of cell division — viz., normal fission,
budding, free cell formation, and karyokinesis.

Normal fission is the simple division of a cell in which the proto-
plasm divides and a partition is formed between the two halves.
Sometimes it takes place by a constriction of the cell-wall.

Budding. — This consists in the formation of a rounded projec-
tion, or bud, on the wall of the parent cell. This bud develops to
normal size, becomes cut off by a partition, and generally separates
from the original cells ; example, yeast.

Free cell formation takes place when the protoplasm of the cell
separates into one or more distinct masses, each mass forming for
itself a cell-wall. The new cells are finally set free by the bursting
of the wall of the parent cell.

Karyokinesis. — This is a form of fission in which the cell under-
goes a cycle of changes, eventually producing two cells from one. It
is more common among animals than plants.

For the study of karyokinesis the growing- tips of onions and the
larvae of salamanders may be used. The cells may be fixed with Flem-
ming's solution or chromic acid. Stain by the usual methods.

The different stages through which the cell passes in karyoki-
nesis are : "Resting nucleus, the skein, the rosette, the aster, the di-
aster, daughter rosettes, daughter skeins, and daughter nuclei.

REPRODUCTION.

Plants and animals reproduce asexually and sexually.

(1) Asexual reproduction. — This method is usually accom-
plished by the individual cell, and there are, therefore, no distinc-
tions of sex, the new cells formed being exactly like the parent cell.

THE CELL. 41

Often spores are formed which differ from the parent cell, but the
spores are evidently asexual, neither being produced by sexual or-
gans nor presenting sexual characteristics.

The varieties of asexual reproduction are the following :
(a) Normal fission, in which a unicellular animal simply divides
into two ; example, bacteria and amoeba?.

(6) Budding. — In this the unicellular organism produces a bud
wlncl. eventually becomes cut off, forming a new individual; ex-
ample, yeast.

(c) By endospores.—In this method new cells are formed with
in a large cell; example, lichens.

(d) Rejuvenescence. — By this process the protoplasm assumes a
rounded mass, escapes from the cell-wall, and forms for itself a
new cell-wall; examples, spirogyras and diatoms.

(e) Spore-reproduction. — The spore is a modified cell, whose
function is to perpetuate and reproduce the species. Spores are
generally formed in a spore case, or sporangium. The structural
elements of the spore are the exosporium,, or outer coat; endospo-
rium, or inner coat ; and the protoplasm. . .

(2) Sexual reproduction. — This occurs when one or two sexual
cells engage to reproduce a plant or animal. Among plants the
sexual elements are the spermatazoids and the oospheres. The
sexual elements of animals are the spermatazoa and the ova. The
varieties of sexual reproduction are conjugation, parthenogenesis,
and fertilization.

(a) Conjugation. — This consists in the union of two like cells.
In some cases the protoplasm of one cell is discharged into that of
another, the resulting cell being called a zygospore, or auxospore;
example, Spirogyra. It may occur, also, by the union of the proto-
plasm of two distinct cells which have previously discarded their
cell-walls. In this method the cells are structurally the same, but
as the process is analagous to that of the sexual method — that is,
cytoplasm fusing with cytoplasm, and nucleus with nucleus, it is
considered by the best authorities as sexual in character ; examples,
diatoms and animalcules.

(#) Parthenogenesis. — This occurs when one sex alone pro-
duces a new individual. A single sexual cell may be concerned or

42 NORMAL HISTOLOGY.

two cells of the same sex. It is illustrated among aphides and cer-
tain of the humbler lepidoptera.

(c) Fertilization. — This occurs when two sexual cells unite to
produce a new individual. It is a process common to higher plants
and animals.

It is evident, therefore, that each individual plant or animal has
its origin in a single cell, and that its organism is developed by a
process of cell-multiplication. For example, by the fusion of the
sexual elements the primordial cell of the animal body is formed.
This cell divides by a process of karyokinesis and forms two cells.
Each of these divides, similarly, forming four cells; the four like-
wise produce eight ; and the eight produce sixteen. This gives what
is called the morula, or mulberry stage. By rearrangement of these
cells in the form of a pouch there is formed the gastrula, the cells
disposing themselves in two layers. From these layers is produced
a middle layer, thus forming the blastoderm, consisting of three
distinct layers, — epiblast mesoblast, and hypoblast. From these
layers, by cell-multiplication, growth and differentiation, all the
structures of the body are produced.

Laboratory exercise No. 4.. — The structure of a cell. Peel from the
outer surface of a scale of an onion bulb a piece of the epidermis. Ap-
ply to a slide and stain for a few moments with rosanilin violet. Wash
with water, apply cover-glass, and examine. Observe first the form of
the cells and their relative positions, then the structure of each cell.
Make out the cell-wall, the nucleus with its nucleolus, and the gran-
ular protoplasm surrounding it. Do you observe any vacuoles? Make
a drawing of several cells, exhibiting the structures above named.

Laboratory exercise No. 5. — To demonstrate protoplasm and cellulose.
Make a preparation similar to the above and apply a drop of iodine
solution. Examine. The protoplasm will be stained brown, but the
cell-wall is not stained. Now remove cover-glass and apply a small
drop of sulphuric acid. This changes the cellulose into soluble dex-
trin, which is attacked by the iodine and turned blue or black. This
is the iodine test for starch. Look for crystals of iodine and for the
Brownian movement among the molecular particles.

THE BROWNIAN MOVEMENT.

This is a molecular movement purely physical in character. It
occurs amoiur bacteria and may be mistaken for independent mo-
tion due to vitality.

THE CELL. 43

A STUDY OF CELLS.

In the following studies it is designed to illustrate the different
forms of cells and the methods of cell-multiplication. Types are
presented which are believed to have a special bearing on the work
of the histologist. Yeast, Protococcus, and Spirogyra have been
selected to illustrate plants, and the Amoeba, Green Euglaena, and
Slipper Animalcule, to illustrate animals.

STUDY OF THE YEAST PLANT.

The Yeast Plant is a unicellular, chlorophylless saprophyte, which
reproduces by budding and ascospores.
Classification:

Kingdom — Vegetable.

Series — Cryptogamia.

Sub-kingdom — Thallophyta.
Class — Fungi.

Sub-class — Ascomycetes.

Life History and Morphology. — The Yeast Plant, Saccharomyces
cervisice, is the common species used by brewers and bakers. It con-
sists of cells, round or oval in outline. Each plant, or cell, is called
a torula; when the cell produces spores the term gonidia, or asco-
spores, is applied to them, while the term ascus is applied to the
cell. The cell-wall is transparent and composed of cellulose. The
protoplasm contains one or more clear spots (vacuoles), and is be-
lieved to contain a nucleus. Multiplication occurs by budding. A
spherical projection, or papilla, is produced on the wall of the parent
cell, which forms for itself a cell-wall, and, eventually, by a parti-
tion, becomes separated and assumes an independent existence. Be-
fore separation occurs, however, owing to rapid growth, the daugh-
ter cells often throw out buds, thus forming a colony or chain. Ee-
production also occurs by the formation of endospores. The proto-
plasm of the parent cell divides into four masses, each of which
forms a new cell-wall. These are called ascospores and have the
power to perpetuate the plant under unfavorable conditions. By
the dissolution of the wall of the parent cell the ascospores are set
free and, under favorable conditions, reproduce the plant.

In size, the yeast plant ranges from T(TVir to *iW inc^ *n diame-

44 NORMAL HISTOLOGY.

ter. In form, the torula is spherical or ovoidal. It has the power

to produce fermentation, thus changing sugar into alcohol and C02.

C6H1206=2C2H5OH + 2C02.

Some of the sugar breaks up into glycerine and succinic acid
Yeast contains no chlorophyl, and, therefore,, has not the power to de-
compose C02. The elements necessary to form its protoplasm, cel-
lulose, fat, etc., are carbon, oxygen, hydrogen, nitrogen, sulphur,
phosphorus, potassium, magnesium, and calcium. These are ob-
tained chiefly from complex substances, which are broken up by
its action, and their elements appropriated to form the new com-
pounds required for its growth and reproduction.

Saccharomyces cervisice is used in making bread, the 00^ formed
permeating the dough and making it spongy. Several species are
used in making beer and other fermented liquors, different flavors
being produced by different species.

Laboratory exercise No. 6. — Teast. Place in a test tube, half filled
-with water, a small portion of a cake of Fleischman's yeast, and let
stand for a few hours in a warm place. Place a drop of the liquid upon
the slide; cover and examine with H. P. Look for single cells; then for
a large cell with a small one attached; the small cell is a bud. Find
a group of cells; this is a colony. Look also for a chain. Irrigate with
magenta, and search for protoplasm and a nucleus.

Upon the freshly cut surface of a potato sow some yeast cells. In a
day or so examine some of the growth and search for ascospores. They
will appear as rounded masses within the larger cells. Make drawings
to illustrate a single cell, a colony, a chain, buds, and ascospores.

PROTOCOCCTJS.

Protococcus is a unicellular, chlorophyl-bearing plant which re-
produces by normal fission and by endospores.
Classification :

Kingdom — Vegetable.
Series — Cryptogamia.

Sub-kingdom — Thallophy ta .
Class — Algaa.

Sub-class. — Chlorophyceae.
Order — Protocaccales.

Family — Protococcaceae.
Genus — Protococcus.

Species — Protococcus vulgaris.
Protococcus pluvialis.
Protococcus nivalis.

THE CELL. 45

Life History and Morphology. — Protococcus vulgaris, Green Pro-
tococcus, is a spherical organism ranging in size from 1-10,000 to
1-350 of an inch in diameter. It consists of a cell-wall (cellulose),
protoplasm, nucleus, and nucleolus. Within the cell the protoplasm
is in green-colored masses containing chlorophyl. These are the
cliromato'phores, or ehloroplasts. Multiplication takes place by fis-
sion. The protoplasm divides first; then a partition is formed be-
tween the two portions, and the cells thus formed separate.
Often, however, before the new cells separate, one or both
may again divide, thus forming groups of three or four cells; these
also may be subject to fission, so that groups of six, eight, etc., may
occur, the number generally being some multiple of two. There are
two states of protococcus: The quiescent, just described; and the
motile form, which is ovoidal in shape and is provided with two
ftagella which, by their contraction, give to the cell a whirling mo-
tion. This state of protococcus is called a zoospore. In course of
time the zoospore loses its flagella and becomes a quiescent cell.

Protococcus pluvialis is found in the gutters of houses, and dif-
fers from the foregoing in possessing a small amount of red pig-
ment. It, also, reproduces by endospores. The protoplasm of the
resting cell divides into four portions or into many portions, in the
former case producing megazoospores, and in the latter, microzo-
ospores. These are set free by the bursting of the wall of the parent
cell.

Protococcus nivalis is the so-called red snow of Arctic regions.

Habitat. — Protococcus vulgaris is found on brick, rocks, fences,
houses, and the bark of trees.

Laboratory exercise No. 7.— Protococcus. From the north side of a
tree or fence obtain some bark or wood containing' a coating' of green
Protoccecus. Moisten and place under a bell jar or in a Petri dish for
twenty-four hours in a warm place. When the cells have begun to vege-
tate, apply the surface of a cover-glass. Some of the cells will adhere.
Add a small drop of water if necessary, and examine with H. P. Ob-
serve the shape, color, and size of the cells. Find a single cell; then
one with a partition showing normal fission. Find also a triplet and
groups of four, eight, etc. Search now for motile forms. These are the
zoospores. Irrigate your preparation with acetic acid, and discover, if
possible, a nucleus. Make drawings illustrating a single cell, doublets,
triplets, and groups of four or more; also zoospores.

46 NORMAL HISTOLOGY.

SPIROGYRA.

Spirogyra is a unicellular, chlorophyl-bearing plant which repro-
duces by normal fission and by conjugation.

Classification :

Kingdom — Vegetable.
Series — Cryptogamia.

Sub-kingdom — Thallophyta.
Class — Algas.

Sub-class — Chlorophyceae.
Order — Conjugatales.

Family — Zygnemacese.
Genus — Spirogyra.

Species — Spirogyra nitida.

Spirogyra maxima.

Life History and Morphology. — Spirogyra maxima, commonly
called Brook Silk, consists of a cylindrical cell, longer than broad.
The cells, placed end to end, are united into long filaments by a
gelatinous secretion. They contain chlorophyl bodies arranged in
spiral form, hence the generic name. These are the cliromato-
phores, or chloroplasts. A nucleus is always present, but not easily
seen. Fission occurs by the normal method and may take place in
any cell of a filament. Eeproduction also takes place by conjuga-
tion— i. e., two adjacent cells of filaments lying near, or in contact
with each other, unite by the protoplasm of one being discharged into
that of the other. This is accomplished by tubular projections being
thrown out from each cell, which meet and form a passageway be-
tween the cells. In this case the cells are alike and distinction of sex
has not yet been discovered. The new cell produced by the conju-
gation is called a zygospore. The encysted zygospore becomes em-
bedded in the mud and preserves the life of the plant through the
winter. If develops into a new plant by the protrusion of the in-
ner coat through the broken outer coat, when fission takes place, and
a filament is produced by the vegetative process. By some, spirogyra
is supposed to illustrate sexual reproduction, the conjugating cells
being the gametes and producing by their union the zygospores. The
sexual character of the cells may yet be proven, for there may be

THE CELL. 47

sexual differences (physiological at least) of which we are yet ig-
norant. The chromatophores often contain bright spots, called
pyrenoids, and are instrumental in producing starch, which, as
minute granules, occurs surrounding the pyrenoids. The cell ex-
hibits cell-wall, primordial-utricle, protoplasm, nucleus, chromato-
phores, starch grains, pyrenoids, and chlorophyl.

Habitat. — Spirogyra may be found in ponds and slow-running
creeks, and is widely distributed. It is somewhat smooth and slimy
to the touch.

Laboratory exercise No. 8. — Obtain from some pond or brook a quan-
tity of Sphogyra, placing it in a large jar with water. Examine with
H. P., observing the filaments composed of cells attached end to end.
Make a study of a single cell. Observe the spiral arrangement of the
chloropiusts. Use the 1-12-inch objective and search for the pyrenoids
and starch granules. Find cells in the process of fission. This is to be
observed where the cells are much shorter than normal size. Irrigate
with a drop of acetic acid, and search for a nucleus. Make drawings
to illustrate filaments and a single cell containing nucleus, chloroplasts,
and cell-wall.

A STUDY OF ANIMAL CELLS.

AMCEBA.

The Amoeba is a unicellular animal devoid of a cell-wall, having
the power to produce pseudopodia, and reproducing by normal .fis-
sion.

Classification:

Kingdom — Animal.

Series — Protozoa.

Sub-kingdom — Protozoa.
Class — Monera.

Order — Amoebea.

Genus — Amoeba.

Species — Amceba proteus.

Life History and Morphology. — The Amoeba is an animal which
appropriates food without a mouth, digests without a stoimich,
breathes without lungs, and has sensation without a nervous sys-
tem. It is simply a mass of protoplasm consisting of cytoplasm and

48 NORMAL HISTOLOGY.

nucleoplasm. The C3^toplasm consists of two layers, the ectoplasm,
or dense, outer hyaline layer, and the endoplasm, or inner layer,
containing the microsomes. The nucleoplasm constitutes the nu-
cleus and contains masses of chromatin, which is very susceptible to
staining reagents.

The animal has the power to throw out protrusions, or pseudo-
podia, from its body. A bulb is formed on the surface of the cyto-
plasm, and then all the protoplasm flows in this direction until,
often, the whole animal has passed into the pseudopodium. In the
meantime,, other pseudopodia are produced. The movement exhib-
ited by the leucocytes of the blood is similar to this and is called the
amoeboid movement. Food is obtained by flowing around it. There
nre two kinds of vacuoles, food vacuoles and water vacuoles. The
contractile vesicle serves the function of excretion. The Amoeba
reproduces by normal fission — that is, the nucleus and protoplasm
divide into two masses, without undergoing any process of mitosis.
There are two stages of this animal, the active stage, just described,
and the encysted, or quiescent, state. When the animal is placed
under unfavorable conditions it contracts into a sphere, forms an
enclosing tough membrane, and in this condition may be wafted by
the air from place to place. Under favorable conditions the proto-
plasm breaks through the enclosing wall, and the animal again en-
ters the active stage.

Habitat. — The Amoeba may be found in ponds or brooks upon
submerged leaves and stems, or in the ooze which collects at the
bottom. To obtain material for laboratory use, collect some grass
and leaves from the side of a stream, also some submerged plants
and ooze from the bottom of a pond or stream, and place in glass
jars for five or six weeks. At the end of this period amoebas should
be obtained in numbers.

Laboratory exercise No. 9. — Amccbce. From the infusion, prepared
as directed, carefully pick out a submerged leaf, and apply some
of the ooze upon its surface to a slide. Cover and examine with
L. P. and H. P. Observe the ectoplasm, endbplasm, and nucleus. Make
out the vacuoles and contractile vesicles. Observe the formation of
pseudopodia. Make drawing's to illustrate protoplasm, nucleus, pseu-
dopodia, and encysted stage.

THE CELL. 49

THE SLIPPER ANIMALCULE.

The Slipper Animalcule may be found in hay infusion. It is a
unicellular animal, provided with a cell-wall, and reproduces by
normal fission.

Classification:

Kingdom — Animal.
Series — Protozoa.

Sub-kingdom — Protozoa.
Class — Infusoria.
Order — Ciliata.

Genus — Paramoecium.

Species — Paramcecium candalum.

Life History and Morphology. — The Slipper Animalcule is a sin-
gle cell provided with cell-wall, protoplasm, a double nucleus
(macro-nucleus and micro-nucleus), two contractile vesicles, and
food and water vacuoles. It receives its food through a mouth.
Leading to the mouth is an cesophagus which terminates near the
middle of the body surface in a depression called the vestibule. This
depression, as well as the whole surface of the cell, is provided with
cilia. The cilia are minute, hair-like, protoplasmic projections
which by their rapid motion enable the animal to move from place
to place. Excretion is accomplished by means of an anal spot. This
is not a permanent opening, but a thin place in the cell-wall through
which the excretions are forced by means of the contractile vesicles.
Reproduction occurs by normal fission, and is accomplished by the
division of the nucleus and protoplasm into two halves and the con-
striction of the cell-wall.

Laboratory exercise No. 10. — Slipper Animalcule. Examine some of
the scum which forms on the surface of hay infusion. Examine with
the high power, and, having- found a specimen of the animalcule in a
quiet condition, observe the following structures: Cell- wall, cilia, vesti-
bule, oesophagus, mouth, protoplasm, double nucleus, food masses, the
water vacuoles, and the contractile vesicles. Make a drawing to illus-
trate the structures thus named.
4

50 NORMAL HISTOLOGY.

GREEN EUGL^INA,

Green Euglsena is a unicellular animal which possesses chloro-
phyl, secures its motion by means of flagella, and reproduces b^
normal fission.

Classification:

Kingdom — Animal. 1

Series — Protozoa.

Sub-kingdom — Protozoa.
Class — Infusoria,

Order — Flagellata.

Genus — Euglsena.

Species — Euglcena viridis.

Life History and Morphology. — Euglwna viridis is an interesting
animal because of the fact that its cell- wall is composed of cellulose
and because it possesses chlorophyl. The cell is fusiform in shape,
and is provided with cell-wall, mouth,, flagellum (extending from
an anterior depression), an eye spot of red pigment situated near
the mouth,, and protoplasm, chloroplasts, and nucleus. It has a
rotary motion. Fission takes places in a longitudinal direction in-
stead o'f transversely, as with the Slipper Animalcule.

Habitat. — The Green Euglsena may be found in damp soil, in
sewerage, and upon the surface of stagnant water.

Laboratory exercise No. 11. — Green Euglaena. Obtain some Green
Euglsena, preferably from the surface of water. Examine with the
high power. Make out carefully the structures mentioned above. Do
you find any evidences of cilia? In what two respects does Euglaena re-
semble a plant? What is your conclusion as to its nature? Drawings.

VEGETABLE CELLS.

Onion Cell. B. Yeast.

A. Onion cell : (a) Cell-wall : (b) Cytoplasm ; (c) Primordial utricle ; (d) Nu-
cleus; (e) Nucleolus; (f) Vacuoles.

B. Yeast plant: (a) Single cell; (b) Cell wall; (c) Protoplasm; (d) Buds; (e)
Colony ; (f) Chain ; (g) Ascospores.

A. Protococcus. B. Spirogyra.

A. Protococcus: (a) Single cell; (b) Cell wall; (c) Chloroplasts ; (d) Cell di-
vision; (e) Groups of three, four, six, etc.; (f) Zoospores; (g) Flagella.

B. Spirogyra: (a) Single cell; (b) Cell wall; (c) Spiral of chloroplasts ; (d)
Nucleus; (e) Pyrenoids; (f) Starch granules ; (g) Cell division ; (h) Conjugation.

[51]

ANIMAL CELLS.

Amoeba.

Amoeba: (a) Active stage; (b) Cytoplasm; (c) Nucleus; (d) Pseudopodia ;
(e) Food vacuoles; (f) Water vacuoles; (g) Contractile vesicle ; (h) Microsomes;
(i) Normal fission ; (j) Encysted stage.

A. Slipper Animalcule. B. Green Euglsena.

A. Slipper Animalcule: (a) Cell-wall; (b) Cilia; (d) Vestibule; (e) CEsophagus;

(f) Mouth; (g) Protoplasm; (h) Macronucleus; (i) Micronucleus; (j) Food masses;

(g) Vacuoles; (h) Contractile vesicles; (i) Normal fission.

B. Green Euglaena: (a) Cell-wall; (b) Chloroplasts ; (c) Mouth; (f) Eye-spot;
(g) Flagellum.

[52]

NORMAL HISTOLOGY. 53

CHAPTEE Y.
TISSUES AND ORGANS.

A tissue consists of intercellular substance and an aggregation of
cells of common origin which usually exhibit a common form, struc-
ture, and function. The intercellular substance may be very slight in
quantity (merely a delicate layer of cement between the cells, as in
epithelial tissue), or it may make up the bulk of the tissue, as illus-
trated in the calcareous deposit of osseous tissue. It is deposited by
the cells and is usually formed by their agency. In some tissues the
cells vary in form; for example, in epithelial tissue, the newly-
formed cells are almost spherical and are rich in protoplasm, while
the old cells are merely flattened scales devoid of protoplasm. In
osseous and nervous tissues the young cells may be spherical or
oval, while the older cells are provided with protoplasmic processes.

An organ is a single tissue which exhibits a special function or a
group of tissues so associated as to accomplish some .definite pur-
pose in the plant-or animal economy. It is often the case that an
organ may serve several purposes; as, for example, the tongue, which
aids in mastication, deglutition, and articulation, and is an organ of
taste and secretion. There is usually, however, one function which
is preeminent. In the structure of an organ it is not the rule that
all its tissues are derived from the same source. The tissues of
the stomach, for example, are derived from the epiderm, mesoderm,
and hypoderm.

As has been suggested in the preceding chapter, all the organs and
tissues of the animal body are derived from a single cell. This cell
is produced by the fusion of a sperm nucleus with a germ nucleus.
From this primordial cell, by a process of segmentation, there is
produced, first, the morula; then the gastrula, with its two
layers — epiblast and hypoblast. From these layers is de-
rived a third layer, the mesoblast. We now have the blastoderm,
consisting of three distinct layers of cells — epiblast, mesoblast, and
hypoblast. From these layers are produced the primitive layers of
the embryo — epiderm from the epiblast, mesoderm from the meso-

54: TISSUES AND ORGANS.

blast, and hypoderm from the hypoblast. From these primitive tis-
sues are derived all the structures of the body.

From the epiderm are developed the nervous system, the epithe-
lium, covering the surface of the body, the enamel, the nails, the
hair, the organs of special sense, and all glands except those which
open into the alimentary tract from the oesophagus downward.

From the mesoderm are derived the blood, blood-vessels, all the
connective tissues (cartilage, bones, tendons, etc.), the muscles, the
dentine, and cementum.

From the hypoderm are developed the epithelial lining of the
alimentary canal and the glands opening into it.

Tissues may be classified into four groups : (1) Epithelial tissues,
(2) Connective tissues, (3) Muscular tissues, (4) Nervous tissues.
The organs of the body are constituted of these tissues. For ex-
ample, the tongue consists of epithelial, muscular, connective, and
nervous tissues. In the following studies tissues and organs are
treated in the order considered most convenient for practical work.
The first structure to be considered is the blood.

MEMORANDA.

NORMAL HISTOLOGY.

55

CHAPTER VI.

THE BLOOD.

The blood is a tissue of mesodermic origin. It consists of cells,
called corpuscles, and an intercellular substance — the plasma, or
liquor sanguinis. The following outline will exhibit its composi-
tion as well as its structural elements :

OUTLINE OF THE BLOOD.

Corpus-
cles . .

Colored

Color- j
...1

Nucleated and bi-convex (amphibia, etc.).
Non-nucleated and bi-concave (mammalia).
( Platelets.

f Lymphocytes.
T Polynuclear elements.

I Leucocytes j Eosinophilous leucocytes.

[ Phagocytes.

Fibrinogen.

Plasma.

Serum.

f Fibrin-ferment..
Serum-globulin.
Serum-albumin.

Serosity

Water.

.Fibrin.

Mineral salts. . .

NaCl.

Na2CO3.

Na3P04.

Ca3(P04)2.

Mg3(P04)2.

Sulphates.

The corpuscles are the cellular elements of the blood. In man
the red corpuscles, being devoid of protoplasm, are not alive, but
the leucocytes exist in the blood as so many distinct amoeboid ani-
mals. They can produce pseudopodia, and have the power of re-
producing themselves by normal fission and karyokinesis. The red

56 NORMAL HISTOLOGY.

corpuscles occupy about fifty per cent of the volume of the blood
in man,, thirty-five per cent in woman. The volume of the white
corpuscles is about two per cent.

Colored corpuscles, — In the blood of man these are usually
styled red discs ; as seen on edge, they appear to bulge at the ex-
tremities and have concave centers. They are devoid of cell-wall,
and on account of their flexibility are capable of crowding through
very narrow spaces.

In the fish, salamander, reptile, and. bird the red corpuscle is
nucleated and bi-convex. Among mammals, including man, it is
bi-eoncave and non-nucleated. Under the microscope the color ap-
pears jrellowish. The red corpuscles are smooth and flexible. Their
color is due to the Ji&maglobin, which is suspended in the pores of
the stroma, or ground substance, of the corpuscle. The haBmaglobin
contains iron, which has a strong affinity for oxygen, forming with
that element oxyk&maglobin, which gives to the blood its bright red
tinge. The dark color of the venous blood is due, therefore, to
the haBmaglobin. The chief function of the red corpuscles is to
serve as a carrier of oxygen. When exposed to the air the red discs
arrange themselves in rows or stacks, which is called the formation
of rouleaux. Water will remove the haemaglobin. Sirup causes the
corpuscles to shrivel. Normal saline produces crenation, due to the
fact that the salt has an affinity for the stroma and produces con-
tractions upon the surface by exosmosis. The red corpuscles are
manufactured in the liver, spleen, and red marrow of the bone. When
first formed they are nucleated, but afterwards lose their nuclei by
mitosis.

The size of the red disc in man is ^Vir of an inch, or about
7.5 p. It would require 40,000 of them to cover the head of a pin.
There are about 350 colored discs to one leucocyte.

Colorless corpuscles. — The white corpuscles consist of the pla-
telets and leucocytes. The platelets are colorless elements, about
TTJVfr °^ an mc^ m diameter. They are sometimes very abundant.
In man the leucocytes are spherical in shape, nucleated, and
larger than the platelets and red disks. They are alive and ex-
hibit the amoeboid movement, throwing out pseudopodia, by means
of which they move from place to place. There are four impor-

THE BLOOD. 57

tant varieties. The lymphocytes are the mono-nucleur elements, and
may be large or small, according as the nucleus more or less than
half fills up the space of the cell. The polynucleur leucocytes pos-
sess more than one nucleus, sometimes four or five nuclei. The
eosinophilous leucocytes are those which take the eosin stain. They
do not act as scavengers in the system. The phagocytes comprise all
leucocytes which are not stained by eosin, or about seventy-five per
cent. They serve as scavengers in the body, removing fat and for-
eign substances from the blood and attacking and destroying ob-
noxious microbes. The leucocytes also assist in the process of anab-
olism, migrating through the stigmata of the capillaries to build up
worn-out tissues and going to the relief of diseased structures. Leu-
cocytes have no cell-wall.

The plasma is the liquid part of the blood and consists of the
fibrinogen and the serum. The fibrinogen is a proteid compound
\\hich under the stimulus of the fibrin-ferment forms the fibrin.
The fibrin is formed when the blood is exposed to air, heat, etc.,
solidifying in slender fibres which collect in their meshes the cor-
puscles, forming a clot. This process is known as coagulation. The
liquid which oozes from the clot is the serum. The serum contains
the fibrin-ferm.ent, the serum-globulin, the serum-albumen, and the
serosity. The first three of these are proteids and contain nutritive
material for the growing cells. The serosity consists of the water
and the mineral salts. The mineral salts commonly found in the
blood are sodium carbonate, sodium chlorid, sodium phosphate, mag-
nesium phosphate, calcium phosphate, and a small amount of sul-
phates.

The microscopic study of the blood is an important aid in de-
termining the condition and relative number of its structural ele-
ments and the presence of invading parasites. The serum of the
blood is believed to be germicidal, but under abnormal conditions
it becomes infested with certain species of bacteria. A species of
Vermes, Distoma Hwmatobium, and a protozoan, Plasmodium
malariw, are two important animal parasites which infest the blood.

Plasmodium malariae. — This parasite is considered by some au-
thorities to be a plant; by others it is placed (with other organisms)
in a separate kingdom, called Protista. The view here adopted (that

58 NORMAL HISTOLOGY.

it is an animal) is the one generally accepted. This organism at-
tacks the red corpuscles, destroying the haemaglobin. It may be
stained with methylene-blue, aqueous or alcoholic solution, and can
be detected as a minute body, irregular in shape, filling about one-
fourth of the corpuscle. Its life history includes five distinct stages :
(1) The spore; (2) the protoplasmic, or fission, stage; (3) the
amoeboid form; (4) the plasmodium, consisting of several amoeboid
forms united; (5) the encysted stage, containing a cell- wall within
which the cell contents break up into spores. This cycle of changes
through which the organism passes accounts for the fact that per-
sons afflicted with malaria experience a recurrence of the symptoms
at stated intervals.

Laboratory exercise No. 12. — Corpuscles., rouleaux, and fibrils of
fibrin. Clean a slide and cover-glass. This step should precede nearly
all the exercises that follow. Wrap the ring finger with a kerchief
from the base to the first joint. Apply a few drops of alcohol to cleanse
the exposed surface, and then, with a lance or sterilized needle, with a
quick motion puncture the skin just above the root of the nail. Wipe
off the first drop of blood, and to the next apply the surface of a cover-
glass. Place this upon a slide, blood down. Now examine with H. P.,
observing first the red corpuscles, which will be found to be collecting
by their flat surfaces into rows, called rouleaux. Examine one of the
discs on edge, then in profile. With fine adjustment focus up and down.
Why does the center of the disc appear alternately dark and light?
Examine now the platelets and leucocytes. They may be found in the
clear spaces between the red discs, and, as they adhere to the glass, do
not float about in the serum. Lay aside this preparation until the next
period and examine for the fibrils of fibrin, which will appear as deli-
cate threads beneath the cover-glass.

Crenation and Amoeboid Movement. Make a second preparation by
the method above described. Add to the blood a small drop of normal
saline. Examine and observe the crenated appearance of the colored
discs. This is due to exosmosis. Gently warm the slide and look for
the amoeboid movement of the leucocytes. To observe this may re-
quire that the slide be kept warm for a considerable period.

Acetic acid brings into view the nuclei of leucocytes. Water removes
the ha?maglobin from red corpuscles, while sirup causes the disc to
shrivel.

Laboratory exercise No. 13. — Preparation of a blood slide. Secure a
drop of blood by the method described, and apply a clean cover-glass.
To this apply a second cover-glass, and with gentle pressure spread out
the blood. Then, with a quick motion, keeping the cover-glasses paral-
lel, draw them apart so as to leave a thin film of blood on each. Select
the best preparation, lay it upon a piece of writing paper, blood up, and

THE BLOOD. 59

hold it over a flame, being careful not to ignite the paper, until the film
turns brown. The blood is now properly affixed, and may be stained
by the following method:

No. XL Scheme for Staining Blood Preparations.

(1) Make a cover-glass preparation and affix by the method given
above.

(2) Using Cornet forceps, stain with alcoholic or glycerine eosin,
thirty minutes to one hour.

(3) Wash off eosin by dipping cover-glass vertically into distilled
water one or two times.

(4) Apply Delafield's haematoxylin fifteen minutes.

(5) Wash in water, dry with gentle heat, and mount in balsam.

(6) Label and study.

Observe that the colored discs are stained red by the eosin, while the
nuclei of the leucocytes are stained blue by the haematoxylin. Find sev-
eral lymphocytes and compare the sizes of their nuclei. Study the poly-
nuclear elements. How many nuclei do you find? Make drawings to
represent the red corpuscles on edge and in profile, rouleaux, crenation,
fibrils of fibrin, lymphocytes, and polynuclear elements.

Laboratory exercise No. 14. — Staining for Plasmodium malariae.

(1) Make a cover glass preparation from a malarial patient by the
usual method.

(2) Stain with alcoholic methylene blue, fifteen minutes.

(3) Wash in water and examine.

(4) Dry, mount and label, if a good specimen.

Search for the organism in the red corpuscles, also in the plasma.
It has no definite form, but may be semi-lunar, spindle-shaped, spher-
ical, etc. It can be recognized by its color, the discs not taking the
blue stain.

Laboratory exercise No. 15.— Counting the Uood corpuscles. Probably
the most satisfactory device for counting the corpuscles is by means of
the centrifuge. Pursue the following method: Attach to the graduated
blood tube a piece of rubber tubing. Having secured a large drop of
blood, fill the graduated tube by gentle suction, and then place it in the
ha3matokrit, making the bearings secure. Revolve the handle of the
centrifuge seventy-seven times in one minute. This will give 5,000 rota-
tions of the haematokrit, resulting in the precipitation of the red cor-
puscles to the outer end of the tube, the leucocytes being arranged next,
and the plasma filling the other end. If the red corpuscles fill half the
tube, standing at the graduation marked " fifty," it indicates that there
are 5,000,000 corpuscles in a cubic millimeter of the blood; if it stands
at the mark " thirty-five," there are 3,500,000 in a cubic millimeter. The
numbers given above indicate the normal amount of corpuscles for man
and woman respectively. Should there be less than the normal number,
it indicates anaemia. Should there be the required number of red disks,
but too many leucocytes, there is an indication of leukaemia. What
other method may be employed for counting corpuscles?

BLOOD.

Structural Elements.

Blood: (a) Red discs in profile showing dark and light centers; (b) Disc on
edge; (c) Rouleaux; (d) Crenation ; (e) Platelets; (f) Leucocytes; (g) Nucleus;
(h) Amoeboid movement; (i) Fission; (j) Fibrils of Fibrin: (k) Crystals of hae-
matin.

A. Leucocytes. B. Plasmodium malarise.

A. Leucocytes : (a) Large lymphocyte ; (b) Small lymphocyte ; (c) Polynuclear
elements.

B. Plasmodium malarias : (a) Corpuscle ; (b) Plasmodium; (c) Spores.

[60]

NORMAL HISTOLOGY. 61

CHAPTER VII.

ENDOTHELIUM AND EPITHELIAL TISSUES

Endothelium, — This structure is of mesodermic origin and con-
sists of a single layer of very thin polyhedral cells united edge to
edge by a cement substance. It lines surfaces not directly ex-
posed to the external atmosphere, such as the surfaces of serous
and synovia! membranes, forming the linings of the heart, blood
tubes, and other organs.

EPITHELIUM.

Epithelium is derived from the epiderm and hypoderm of the
embryo. It consists of cells of various shapes, which are united by
cement and are devoid of blood-vessels. The important functions of
epithelium are protection, secretion, and elimination. The shape
of the cells depends upon the amount and kind of pressure exerted
upon them. As a rule, when first formed, they are spherical. New
cells are produced by karyokinesis. Blood vessels being absent,
nourishment takes place by absorption.

The following are the important varieties :

Squamous. — Simple and Stratified.

Columnar. — Simple and Stratified.

Ciliated. — Simple and Stratified.

Modified. — Goblet, Pigmented, and Transitional.

Specialized. — Glandular and N euro-epithelium.

Squamous epithelium. — This structure consists of irregular,
polyhedral, flattened cells, united edge to edge in the form of a pave-
ment. The cells, when seen on edge, are found to be somewhat bi-
convex. The nucleus is somewhat eccentric. Squamous epithelium
is found wherever surfaces are subjected to considerable friction.
There are two varieties — viz., simple and stratified. Simple
squamous epithelium consists of a single layer of cells and is found
lining the air cells of the lungs, the capsule of the Malpighian body,
the descending limb of Henle's arch, parts of the brain-ventricles,
and a few other places.

The stratified variety consists of several layers and is found cov-

62 NOKMAL HISTOLOGY.

ering the skin, mouth, tongue, lower half of pharynx, oesophagus,
epiglottis, upper part of larynx, pelvis of kidney, ureter, bladder,
beginning and end of male urethra, and the whole female urethra.

The deeper layers of this tissue have cells more nearly spherical,
which are often connected with each other by slender processes.
These procesess give rise to the so-called prickle cells of the deeper
layers of the epidermis. The cells of the outer layer become much
flattened., lose their protoplasm, and by constant friction are worn
away and cast off. This process is called desquamation.

Columnar epithelium. — This form of epithelial tissue is consti-
tuted of cells which are colummar in shape as seen from the side,
but from above they appear hexagonal. The first layer, resting
upon the membrana propria, consists of spherical cells, but those
of the next layer are oval. Simple colummar epithelium is found
lining the mucous membrane of the alimentary tract from the car-
diac orifice downward. The stratified variety is found in the ex-
cretory ducts of glands leading into the alimentary tract and in a
portion of the male urethra. This tissue is of hypodermic origin.

Ciliated epithelium, — This resembles columnar epithelium, but
the outermost layer of cells is provided with cilia. Cilia are delicate
protoplasmic projections which by their motion produce outward
currents of mucus and other products. The cells are nucleated and
rest upon a basement membrane. Ciliated epithelium occurs in the
nasal cavities, the Eustachian tubes, larynx, trachea, bronchi, a por-
tion of the uterus, Fallopian tubes, vasa efferentia (partly), the ven-
tricles of the brain, and the central canal of the spinal cord.

Modified epithelium. — This is represented by modifications of
the types given above. The important varieties are goblet cells,
pigmented epithelium, and transitional epithelium.

Goblet cells are modifications of columnar or ciliated cells. Each
cell is generally isolated from others of like character and is formed
by the elaboration of mucin from the protoplasm, which so fills up
the cell as to cause it to become swollen and elliptical in. shape.
Eventually the cell bursts, discharging its contents upon the surface
of the membrane. This is one source of mucus, and hence the term
mucous membrane.

Pigmented epithelium. — This is represented by cells of the squa-

ENDOTHELIUM AND EPITHELIAL TISSUES. 63

mous type which have become impregnated with melanin, a dark
pigment that gives coloration to the structure. The pigmeiited
epithelium of the retina is the best illustration.

Transitional epithelium. — This occurs in the urinary tract and is
illustrated by modifications of squamous and columnar cells, where
the one kind merges into the other. It occurs in the pelvis of the
kidney, ureter, bladder, and urethra. The cells are round, spindle-
shaped, cuboidal, or pear-shaped, and often exhibit one or more
slender processes.

Specialized epithelium. — This form of epithelial tissue consists
of cells so specialized as to engage in the elaboration of secretions ;
or to perform some special function. There are two varieties —
glandular epithelium and neuro-epithelium.

Glandular epithelium. — The terms cuboidal and secretory also
apply to this tissue, the former arising from the general shape of
the cells, the latter from their functional character. It occurs in
the intestinal, gastric, and salivary glands, the pancreas, and liver.

Neuro-epitlielium. — This comprises highly specialized cells which
aid in nerve sensation. They are found at the terminations of the
nerves of special sense. The cells are generally elongated and con-
tain an inner nuclear part and an outer part directed toward the
periphery, which is often provided with hair-like processes. The
rods and cones of the retina and the olfactory and taste cells are
illustrations.

The following ten characteristics of epithelial cells should be
carefully considered: (1) The cells are superficially disposed; (2)
they are united by cement; (3) they contain no blood-ves-
sel? : (4) they vary greatly in shape ; (5) they perform various func-
tions, those of protection and secretion being the more common;
(Cl) the cells multiply by karyokinesis ; (7) they are nourished by
absorption; (8) they have eccentric nuclei; (9) they rest upon a
ba?emenl membrane, or membrana propria; (10) the cells contain
mucin, melanin, etc. It should be borne in mind that all these char-
acteristics are not universally present.

Laboratory exercise No. 16. — Study of epithelial cells. Collect upon
the end of the tongue a quantity of saliva and apply the same to the
center of a slide. Cover and examine with high power. Observe the

64 NORMAL HISTOLOGY.

cells, scarcely visible, and note the protoplasm, nuclei, and nucleoli,
also the cell-wall. View a cell on edge. Is it perfectly flat? Find a
group of cells and notice how they are joined together. Search for
small spherical bodies. These are the salivary corpuscles, and are in
reality escaped lymphoid cells from the adenoid tissue at the root of
the tongue.

Place upon the slide some of the scrapings from the pharynx (upper
part) of a frog. Examine with H. P. and observe the elongated cells
with cilia in motion. Ciliated cells may also be demonstrated from
scrapings of the macerated trachea of a pig or ox.

Examine the scrapings of the stomach of some animal. Observe the
columnar cells. Scrape the cut surface of a liver with a scalpel and
mix the scrapings with normal saline. Examine and search for hepatic
cells, representing glandular epithelium.

Epithelium of a frog. Macerate the larva of a frog or salamander in
dilute alcohol, cut the casts from, the skin into small pieces, and apply
one of these to a slide and stain with haematoxylin, method No. 5.

MEMORANDA.

EPITHELIAL TISSUE.

A. Squamous epithelium. B. Columnar epithelium.

A. Squamous epithelium: (a) Squamous cell; (b) Cell -wall; (c) Protoplasm;
(d) Nucleus; (e) Nucleolus; (f) Cell on edge; (g) Group of cells; (h) Salivary cor-
puscle ; (i) Epithelium of a frog.

B. Columnar epithelium : (a) Columnar cells from stomach showing cell -wall
and nucleus— flat surface ; (b) Columnar cells— end view.

A. Ciliated epithelium. B. Glandular epithelium.

A. Ciliated cells: (a) Cells, showing cell- wall and nucleus; (b) Cilia; (c) Gob-
let ceUs; (d) Section of stratified ciliated epithelium.

B. Glandular epithelium: (a) Cuboidal cells from liver; (b) Nucleus.

5 [65]

NORMAL HISTOLOGY.

CHAPTER VIII.

CONNECTIVE TISSUE.

Connective tissue is derived from the mesoblast and consists of
cells and intercellular substance. It is found between the skin and
mucous membranes. It differs chiefly from epithelial tissue in
having a greater amount of intercellular substance. Its functions
are to connect different structures and furnish support to the or-
gans of the body. The cells entering into it are of two kinds, fixed
and wandering. The fixed cell is a flattened plate with nucleus,
protoplasm, and enclosing membrane. Sometimes there are projec-
tions of the cell-wall which give a stellate appearance. Wandering
cells (such as leucocytes) are those which migrate from place to
place in the tissue.

There are ten important kinds of connective tissues — viz., white
fibrous tissue, yellow elastic tissue, areolar tissue, adipose tissue,
mucous tissue, retiform tissue, basement membranes, cartilage, bone,
and dentine.

I. WHITE FIBROUS TISSUE.

This form is composed of delicate fibrils, often collected into bun-
dles. The bundles may run parallel with each other or interlace,
forming a mesh-work. This tissue is found in tendons, the omen-
turn, subcutaneous tissues, etc. In a tendon the fibrils compose
parallel primary bundles, and these unite to form secondary bun-
dles, each of which is enveloped in a delicate sheath. All are bound
together to form the tendon, which is encased in a tough sheath of
connective tissue, septa from which extend inward, enclosing the
secondary bundles.

laboratory exercise No. 17. — Tendon. Embed a piece of tendon in
celloidin. Stain sections with carmine, method No. 2. Make out the ex-
ternal sheath and the septa of connective tissue. Observe the branched
spaces for tendon cells. Demonstrate, if possible, the primary bundles
and the ends of the fibrils. Label and preserve. Drawing's.

II. YELLOW ELASTIC TISSUE.

This consists of highly refracting fibres which form a network
and are often associated with the preceding tissue. The fibres, when

CONNECTIVE TISSUE. 67

free from their attachments, become bent or coiled, and, when boiled,
yield elastin, and not gelatin, as is the case with white fibres. This
structure occurs in the ligamentum nuchw, ligamenta subflava,
walls of bronchioles and alveoli of lungs, arteries, vocal cords, and
in connective tissue generally. This and the preceding form of con-
nective tissue are intercellular in character and are, therefore, asso-
ciated with cells in the formation of tissues. For the practical
study of elastic fibres,, the ligamentum nuchw of an ox may be used.

III. AREOLAR TISSUE.

Areolar tissue is composed of cells and an intercellular substance
which consists chiefly of white and elastic fibers. It lines the un-
der surface of the skin, forms the muscle sheaths, and is found in the
mammary gland and other structures.

IV. ADIPOSE TISSUE.

Adipose tissue is almost wholly cellular. The cells are probably
formed from connective tissue corpuscles, in which fat globules ap-
pear, increase in size, and finally coalesce. Thus is formed one large
globule of fat, which distends the cell-wall, crowding the protoplasm
and nucleus outward. The cells are well supplied with blood capil-
laries. They are bound together by areolar tissue into lobules, and
the lobules into lobes. For practical study, a section of the tongue
will be found satisfactory. It is widely distributed, occurring al-
most everywhere that connective tissue is found.

V. MUCOUS TISSUE.

This occurs in the umbilical cord and comprises cells and a gel-
atinous intercellular substance called the jelly of Wharton. The
cells are stellate in form, and the protoplasmic processes anasto-
mose with each other, forming a mesh- work throughout the struc-
ture. This tissue contains but few fibrous elements, except as the
cord approaches full time.

Laboratory exercise No. 18. — Umbilical cord. Embed pieces of a
three-months' umbilical cord in celloidin. Stain with haematoxylin,
method No. 5. Observe (1) a thin layer of superficial cells; (2) the
blood-vessels, two arteries and one vein, surrounded by the mucous
tissue, the jelly of Wharton, or mucin, containing- the stellate cells;
(3) look also for white or elastic fibres. In what other structure is
mucous tissue found?

68 NORMAL HISTOLOGY.

VI. ADENOID TISSUE.

Adenoid tissue consists of a network of fibrils holding in their
meshes lymphoid cells and leucocytes. The fibrils are supposed to
be derived from cell-processes, which anastomose with each other.
The nuclei of the cells appear at the intersections of the fibrils. It
occurs in lymphatic glands, tonsils, solitary glands, and Peyer's
patches, many mucous membranes, spleen, and thymus gland.

VII. BASEMENT MEMBRANE, OR MEMBRANA PROPRIA.

The basement membrane, or membrana propria, consists of a
delicate homogeneous membrane, composed of flattened plates of
cellular origin, and occurs as a supporting base for the epithelial
cells which line mucous membranes and the acini and ducts of
glands.

VIII. CARTILAGE.

Cartilage is a dense tissue made up of an enclosing sheath, the
perichondrium, a somewhat hyaline matrix, either homogeneous or
fibrous, and cells.

The perichondrium is the enclosing sheath of connective tissue,
and consists of two layers, an outer layer of dense fibrous tissue and
an inner, looser layer. The terms fibrous and chondrogenetic apply
respectively to these layers. The latter is so called because it is
chiefly engaged in the formation of cartilage. It contains cells ar-
ranged in parallel rows, which multiply by mitosis.

The matrix is a dense, intercellular substance of a white, bluish,
or yellowish color. It may be homogeneous or more or less supplied
with white or yellow fibres.

Embedded in the matrix are the cartilage cells. These cells are
usually oval in outline, but are sometimes flattened on one side, the
flattened surface being toward the periphery. They are arranged
in pairs and groups, and are seldom crowded, except toward the
perichondrium. Each cell is enclosed by a capsule. The space
within the capsule, which is filled up by the cell, is called a lacuna.
There are three varieties of cartilage, determined by the presence
or absence of white and yellow fibres. They are hyaline cartilage,
elastic cartilage, and fibro-cartilage.

CONNECTIVE TISSUE. 69

(1) HYALINE CARTILAGE.

THis is characterized by a bluish- white, semi-transparent matrix,
free from fibres It occurs in costal cartilages, the articular ends of
bone, the trachea, bronchi, larynx, the auditory meatus, and in the
early cartilage of the foetus.

Laboratory exercise No. 19. — Hyaline cartilage. Harden pieces of
costal cartilage, or of the sternum of a newt, in picric acid; embed in
celloidin; stain with hsematoxylin, method No. 5, or carmine, method
No. 2. Examine with L. P. and note the following- structures: (1) The
perichondrium with its fibrous and chondrogenetic layers; (2) the
matrix, free from fibres, in which are embedded the cells; (3) the cells,
lying in their lacunaB with inclosing capsule, and arranged in groups
of two or more. Compare the form, size, and disposition of the more
centrally located cells with those toward the surface. Do you observe
nucleoli? Drawings.

(2) ELASTIC CARTILAGE.

This form is characterized by the presence of yellow elastic fibres
in the matrix, They first appear as minute granules, which arrange
themselves in linear rows and, coalescing, form the fibres. The
color of the matrix is yellowish. Elastic cartilage occurs-:- in the
epiglottis, the external ear, the Eustachian tube, etc.

Laboratory exercise No. 20. — Elastic cartilage. Harden portions of
the ear of a pig in picric acid, embed in celloidin, and stain with hsema-
toxylin, method No. 5. Observe, as in the preceding preparation, the
perichondrium, matrix, and cells. Note also the yellow, interlacing
fibres, which extend from the matrix into the perichondrium. Minute
granules of elastin will also be seen with the high power. Make out
the capsule, lacuna, and cell structure. Prepare drawings to illustrate
all of these structures.

(3) FIBRO-CARTILAGE.

Here we have the same structures as exhibited in hyaline carti-
lage, but the matrix is provided with many bundles of white fibres,
running in different directions and interlacing. It occurs In the
intervertebral disks, sesamoid bones, etc.

Laboratory exercise No. 21. — Fil)ro-cartilage. Decalcify and harden
with picric acid pieces of the vertebral column of a cat so as to include
the intervertebral disk, or use the intervertebral disk of an ox. Freeze
or embed in celloidin. Stain with lithium carmine, method No. 2.
Examine and note the numerous bundles of wavy fibres, between which

TO NORMAL HISTOLOGY.

are the cartilage cells, each inclosed in a thick capsule. Make drawings
of all cartilage structures.

IX. BONE.

Bone is a compact, hard form of connective tissue. It comprises
two varieties — spongy and compact. The spongy form occurs in the
v.'itebra* and the ends of the long bones. Compact bone is formed
from the spongy variety by the deposit of lamellae in the intrat rabec-
ular spaces. It is found chiefly in long bones between the articular
ends. A bone comprises three characteristic structures — viz., the
periosteum, the lone-proper, and the marrow.

The periosteum consists of two layers, the fibrous layer of dense
fibrous connective tissue which, as a protecting sheath, covers the
outer surface, and the osteogenetic layer, a somewhat loose struc-
ture, rich in cells and blood-vessels. This layer is so called because
it assists in forming bone. Its cells eventually become the osteo-
blasts, which are the bone builders. There are slender portions of
the periosteum which project into the bone proper. They are called
the perforating fibers of Sharpey. They are fibers of the periosteum
which have failed to ossify.

The bone-proper is composed of cartilage and the carbonate and
phosphate of lime. Structurally considered, it comprises the Haver-
sian systems, the inter-Haversian systems, and the fundamental
lamellce. A Haversian system comprises the Haversian canal, the
lamellw, lacunae, canaliculi, and the bone cells. The Haversian
canal is a minute channel, from 20 // to 100 >j. in diameter, extend-
ing longitudinally and opening upon both the inner and outer sur-
face of the bone-proper. It contains an extension of the marrow,
and is rich in blood-vessels, cells, and lymphatics.

The lamellae are plates of bone substance formed in the spaces
between the lacuna? and arranged concentrically around the canals.
The lacunae are the cavities which contain the bone cells. The cavi-
ties which are excavated by and contain the osteoclasts are called
How ship' s lacunw. The canaliculi are the slender tubes which ra-
diate from the lacuna? and serve as lymph channels, distributing nu-
trient fluids throughout the Haversian system. They anastomose
with each other and are connected with the canals. The bone cells
are the corpuscles within the lacunae. They send out processes into

CONNECTIVE TISSUE. 71

the canaliculi. They are derived from the osteoblasts by the in-
corporation of the latter within the bone matrix. Besides the Ha-
versian system (with its lamellae) just described, there are the inter-
Haversian, or interstitial lamella;, and the fundamental lamella?.
The fundamental lamella cover the free surfaces of the bone ad-
jacent to the periosteum and the marrow. The canals of these lamel-
lae are styled Volkman's canals.

The medulla, or marrow, occupies the central cavity. It is de-
rived from the osteogenetic layer of the periosteum. It is composed
of a connective tissue reticulum filled with cells and supplied with
an elaborate system of blood-vessels. The connective tissue cells,
or marrow cells, in young bone, become the osteoblasts; but, in old
bone, deteriorate into fat cells. Primary marrow is. red, but in the
adult bone it becomes yellow, owing to the formation of fat. The
marrow also contains certain large cells which are agents in the de-
struction of bone. They are called giant cells, osteoclasts, or my-
eloplaxes. They multiply by free cell-formation, and are also founl
in the osteogenetic layer of the periosteum. The marrow is con-
sidered an extension of this layer.

Bone formation. — Bone is formed by two methods — centrally,
within the cartilage., and superficially, by the periosteum. By the
first method a center of ossification is produced by the transforma-
tion of the cartilage cells into osteoblasts. By these cells a cen-
tral core of bone (or bone areas) is formed. At the same time a
layer of bone is formed beneath the periosteum, and trabecula? are
thrown out from the osteogenetic layer, which extend to the center
of ossification and absorb the endochondral bone, thus producing a
central cavity for the marrow. By means of the osteoblasts the
permanent bone is now produced between the marrow-cavity and
the periosteum. Spongy bone is constituted of periosteum, a mesh-
work of trabeculaa, and marrow, rich in osteoblasts, etc., filling up
thi- spaces.

Laboratory exercise No. 22. — Bone. Harden and decalcify pieces of
long bone in picric acid, freeze or embed in paraffin, and stain with
picro-carmine or hsematoxylin, method No. 5. Examine with L. P. and
H. P. Make a study of the periosteum, observing the fibrous layer, con-
sisting of dense fibrous tissue, and the osteogenetic layer, consisting of
a loose fibrous reticulum rich in cells and blood vessels. Search for

72 NORMAL HISTOLOGY,

lacunae in the bone proper and note their arrangement; also find Haver-
sian canals and make out, if you can, Haversian systems. Examine
the marrow and demonstrate marrow cells and osteoclasts. Prepared
specimens of dry bone should be examined to demonstrate lacunae and
canaliculi. The bone of a foetus may be prepared for the study of bone
development. The preparations need not be preserved unless especially
good. What is the average diameter of the canaliculi? Drawings.

X. DENTINE.

Dentine is one of the connective tissues, being derived from the
mesoderm. It is commonly known as ivory and is found in the
teeth. It differs from bone in composition and structure. Its inti-
mate structure will be given in the chapter on the teeth.

MEMORANDA.

CONNECTIVE TISSUES.

A. White Fibrous Tissue. B. Mucous Tissue.

A. Tendon: (a) Tendon sheath; (b) Septa; (c) Bundles; (d) Fibrils; (e)
Branched cell spaces; (f) Longitudinal section.

B. Umbilical cord: (a) Superficial cells from amnion; (b) Arteries; (c) Vein;
(d) Jelly ofWharton; (e) Stellate cells; (f) Connective tissue fibres.

Hyaline Cartilage.

Hyaline cartilage: (a) Fibrous layer of perichondrium; (b) Chondrogenetic
layer; (c)Matrix; (d) Capsule; (e) Lacuna; (f) Cartilage cell; (g) Group of cells.

[73]

CONNECTIVE TISSUES.

A. Elastic Cartilage. B. Fibro-Cartilage.

A. Elastic Cartilage (ear): (a) Ferichondrium; (b) Matrix; (c) Capsule; (d)
Lacuna and cell; (e) Interlacing elastic fibres.

B. Fibre-cartilage: (a) Matrix; (b) Bundles of fibres; (c) Capsule; (d) Cells
and osteoblasts.

Bone.

Bone: A. Periosteum: (a) Fibrous layer; (b) Osteogenetic layer; (c) Cells;
(d) Fibres of Sharpey.

B. Bone proper: (e) Haversian system: (f) Haversian canal; (g) Lamellae;
(h) Lacunae; (i) Canaliculi; (j) Bone cells; (k) In ter-Haversian systems; (1) Fun-
damental lamellae; (m) Howship's lacunae and osteoclasts.

C. Marrow: (n) Marrow cells; (o) Osteoclasts; (p) Osteoblasts.

[74]

NORMAL HISTOLOGY.

75

CHAPTER IX.

MUSCULAR TISSUE.

Muscle is a tissue derived from the mesoderm. It is composed of
cells and a small amount of intercellular substance, and is endowed
with the property of contractility.

OUTLINE OF MUSCULAR TISSUE.

1. Kinds.

3. Functions.

2. Structure. .

Smooth — in all involuntary muscle except heart and

pharynx.
Striated — in heart, O3sophag%us, and all voluntary muscle.

' Smooth
muscle . . J

Form.
Structure.

Striated
muscle. .

f Cells

Bundles.

Strata.

f Epimysium.
Sheaths . . <j

[_ Perimysium.

Fasciculi, composed of fibres.

f Sarcolemma.

f Cells <( Sarcoph

I

1 Nuclei.

Fibers. . . . \

( Fibrillae.

S a r c os -
tyles . . .

Discs.

Dark.
Lateral.

Interme-
diate.

There are two kinds of muscular tissue — (1) smooth, or vegeta-
tive; (2) striated, or animal.

Smooth muscle is associated with all involuntary muscles except
the heart and pharynx, and is found, therefore, in the digestive tract,

76 NORMAL HISTOLOGY

the digestive glands, urinary glands, generative organs, respiratory
tract, vascular system, lymphatic glands, skin, etc.

Smooth muscle is composed of spindle-shaped cells, each consist-
ing of a cell-wall, protoplasm, and a centrally-located nucleus. The
cells overlap by their extremities and are bound together into bun-
dles, each bundle being surrounded by a membrane of areolar con-
nective tissue, called the perimysium. The bundles are disposed in
layers, or strata, the whole muscle being covered by the epimysium,
a connective tissue sheath.

Striped muscle. — This is composed of elongated, somewhat cylin-
drical cells, each consisting of a cell-wall (sarcolemma), protoplasm
(sarcoplasm), and a superficially located nucleus. These cells are at-
tached end to end, thus constituting a slender filament, which is the
muscle fibre. The fibre, therefore, is encased by a delicate, closely-
fitting membrane, the sarcolemma. It exhibits striations, or alter-
nate bands of light and dark, called disks. The nucleus is to be
found upon the surface of the cell just beneath the sarcolemma.
Each fibre is composed of sarcostyles and sarcoplasm. Bach sarco-
style consists of a group of ultimate fibrillw, which are held together
by the surrounding sarcoplasm. Each ultimate fibril is believed to
consist of a prismatic body, a dot, and a delicate filament, the dot
dividing the filament midway between the prisms. This peculiar
structure is supposed to account for the striations of the fibre, the
band of prisms giving rise to the dark disks, the delicate filaments
producing the light lateral disks, and the dots forming the intermi-
date disks. It will thus be seen that a voluntary muscle is com-
posed of bundles, the bundles are composed of fibres, the fibres of
sarcostyles, the sarcostyles of fibrillse, and the fibrillse of peculr'ar
structural elements, sarcoplasm filling up the spaces between these
elements. The fibrillas are the contractile elements. Contraction
takes places in a longitudinal direction, not in every direction, as is
the case with naked protoplasm.

Enclosing each fibre is a sheath of areolar connective tissue, the
endomysium. This is not to be confounded with the sarcolemina,
which is a part of the fibre. Surrounding each fasciculus, or bun-
dle, is a larger sheath, the perimysium; while the sheath enclosing
the whole muscle is the epimysium.

MUSCULAR TISSUE.

77

The striated fibres of the heart differ from the voluntary stri-
ated fibres in being devoid of a sarcolemma and in having their nu-
clei centrally located.

Laboratory exercise No. 23. — Striated muscle. Harden pieces of vol-
untary muscle of salamander or cat in alcohol, embed in paraffin, and
stain with carmine, method No. 3. Make two sections, longitudinal and
transverse.

L.S. Observe the fibres running parallel with each other. Using the
high power, demonstrate the stria tions of the fibres — dark, lateral, and
intermediate. Examine the ends of the torn fibres and search for the
ultimate fibrils. Try and demonstrate the sarcolemma. The tissue of
a salamander will give the best results.

T.S. Examine a section of an entire muscle, if possible, and demon-
strate the epimysium, perimysium, and endomysium. Focus upon the
end of a fibre and locate the nucleus near the outer surface. What are
Cohnheim's areas?

Incubator.

Bausch & Lomb Optical Co., Rochester, N. Y.

MUSCULAR TISSUE.

Striated Muscle.

Striated muscle: T. S.: (a)Epimysium; (b) Pirimysium; (c)Endomysium; (d)
Fasciculus; (e) Fibre; (f) Nucleus; (g) Cohnheim's area.

L. S.: (h) Fibre; (i) Sarcolemma; (j) Dark disk; (k) Lateral disk; (1) Interme-
diate disk; (m) Nucleus; (n) Sarcostyle; (o) Ultimate fibril.

Smooth Muscle.

Smooth Muscle: (a) Single cells; (b) Nucleus; (c) Group of cells; (d) Perimy-
»ium; (e) Epimysium.

[78]

NORMAL HISTOLOGY.

79

CHAPTER X.
NERVOUS TISSUES AND SYSTEMS.

1. NERVOUS TISSUE.

Nervous tissue is derived from the epiderm of the embryo and en-
ters into the structure of the central, sympathetic and terminal sys-
tems, and is, therefore, very widely distributed. The following out-
line exhibits something of the more common characteristics of
nervous tissue :

OUTLINE OF NERVOUS TISSUE.

Cells

Ganglia

Fibres

Structure . .

Kinds .

Processes. . .

Cells.

Fibres.

Sheath.

Medullated.

Non-medul-
lated i

Nucleus.
Protoplasm.

Neuroblast.

Neuron.

Neuro-dendron.

Unipolar.

Bipolar.

Multipolar.

First-type.

Second-type.

Neuroglia-cell or glia-cell.

Axis cylinder.

Collaterals.

Dendrites.

' Structure

Nerve endings ,

( Neurilemma.
Medullary sheath.
Axilemma.
Axis cylinder.
Fibrils.

Nodes of Ranvier.
Internodes.
Nerve corpuscle.

Central.
Peripheral.

Nodes and internodes.

Nerve corpuscle and Neurilemma.

80 NORMAL HISTOLOGY.

Nervous tissue is composed of cells, ganglia, and nerve fibres.
A nerve cell is devoid of a cell-wall; its nucleus has a prominent
nucleolus, and its protoplasm sometimes contains yellowish gran-
ules of pigment. The cells are the most abundant in nerve centers —
the brain, spinal cord, and ganglia. The primitive nerve cells are
called neurollasts, and in the course of their development, by send-
ing out certain processes known as axis cylinders and dendrites, pro-
duce the different forms described as the dendron, neuro-dendron,
unipolar, bipolar, and multipolar cells, and first-type and second-
type cells. An axis cylinder is a slender protoplasmic growth from
the pointed end of a neuroblast. The dendrites are protoplasmic
growths which arise from other parts of the cell. The axis cylinder
attains considerable length, often as much as a meter; the dendrites
are short and slender. The axis cylinder gives off a few lateral
processes called collaterals; the dendrites branch dichotomously,
forming a dense network. The axis cylinder functions as a nerve
fibre; the dendrites possibly serve as a supporting framework for
the neuroplasm, and are supposed to be continuous with the ulti-
mate fibrils. A nerve cell with its axis cylinder is a neuron; a cell
with dendrites and an axis cylinder bearing collaterals is a neuro-
dendron, Cells are named also from the number of processes they
bear — unipolar, one process ; bipolar, two processes ; multipolar, sev-
eral processes. A first-type cell is one which has a long axis cylinder
that becomes a medullated nerve fibre. A cell of the second-type has
a short axis cylinder which divides and subdivides. The neuroglia-
cells are small bodies which give off a multitude of fibrils forming
a supporting network, serving as connective tissue elements, and
holding together the delicate structures which enter into nerve cen-
ters. They are called glia cells, and the reticulum produced by
them is neuroglia.

Ganglia are nerve centers consisting of groups of cells and fibres.
Some of the fibres which enter the ganglion terminate in its cells,
while others pass through to more distant points. The whole gan-
glion is invested with a connective tissue sheath, and each fibre is
enclosed with an endoneurium, which is continuous with the cap-
sule with which the fibre terminates. The brain and spinal cord
may be considered as groups of large ganglia.

NERVOUS TISSUES AND SYSTEMS. 81

Fibres. — A nerve fibre is derived from an axis cylinder of a gan-
glion cell. A ganglion cell is a cell of the first-type, producing a
medullated fibre. The sheath which invests the whole fibre is the
neurilemma, or primitive sheath. It is a thin, transparent, tough
membrane of areolar connective tissue. Directly beneath the neuri-
lemma is the medullary sheath, which consists of a semi-fluid, high-
ly-refracting substance, called myelin. Beneath the medullary
sheath and immediately surrounding the axis cylinder is a delicate
and very thin investment, the axilemma. The axis cylinder is the
essential part of the fibre. It may be naked, or covered with medullary
sheath alone, or with neurilemma alone, or with both. The medul-
lary sheath is absent in the nerves of the sympathetic system and
occasionally in those of the cerebro-spinal system. The neurilemma
is absent in the fibres which traverse the brain and spinal cord. It
is also absent in the fibres of the olfactory nerves. At certain reg-
ular intervals, the medullated fibres lose their medullary sheath, and
the neurilemma closes down upon the axis cylinder. These points
are called the nodes of Ranvier. The space between two nodes is
the internode. About midway of the internode, just beneath the
neurilemma, is the nerve corpuscle.

The non-meduliated fibres occur in the sympathetic system. Each
fibre consists of axis cylinder (composed of a bundle of fibrils), the
neurilemma, and an oval nucleus upon the surface of the fibre.

II. NERVOUS SYSTEMS.

There are three important nervous systems — central nervous sys-
tem, sympathetic system, and terminal system.

CENTRAL NERVOUS SYSTEM.

This is sometimes called the cerebro-spinal system. It consists
of the spinal cord and brain. Each of these is constituted of gan-
glion cells, nerve fibres, neuroglia, and connective tissue.

SPINAL CORD.

The spinal cord, located in the spinal column, consists of gray
and white nervous matter. The gray matter is in the center of the
cord, and the white matter surrounds it. The gray matter is made

82

NORMAL HISTOLOGY.

up of ganglion cells, neuroglia, and fibres, while the white matter
consists chiefly of medullated fibres and connective tissue.
OUTLINE OF THE SPINAL CORD.

Fissures .

White sub-
stance. . .

Gray sub-
stance. . ,

Neuroglia.

Investments.

Anterior median fissure.
Posterior median septum.
Anterior lateral column.

Posterior lateral ( Column of Goll.

column <

[ Column of Burdoch.

Anterior gray commissure.
Posterior gray commissure.
Central canal.

Lateral columns

f Anterior roots.
f Anterior cornua . . < .-

[ Posterior roots.

f Reticular pro-
| cess.

Posterior cornua . •{ Column of Clark.
Substantia gel-
atinosa.

Lateral cornua.

Multipolar
cells. . .

Structure

Motor cells

Nucleus and
nucleolus.

Nuclear mem-
brane.

Axis cylinder.

Dendrites.

f Antero-median
group.

j Postero-lateral
group.

Column cells.

f Ependymal cells.
[ Deiter's cells.

Dura mater.

Arachnoid membrane.

Pia mater.

Septa from pia mater.

NERVOUS TISSUES AND SYSTEMS. 83

The surface of the spinal cord comprises four areas : Anterior,
posterior, and two lateral areas. The cord is divided vertically into
two lateral halves by the anterior median fissure and the posterior
median septum. These fissures do not extend through the com-
missures,

Each half of the spinal cord is divided into the anterior column,
posterior column, and lateral column. These divisions are marked
by furrows indicating the exit of the anterior and posterior roots of
the spinal nerves. In the upper thoracic and lower cervical regions,
two divisions appear in the posterior column, a median portion,
called the column of Goll, and a lateral portion, the column of Bur-
dock.

The white matter is held together by septa of connective tissue
which proceed from the pia mater. Under the microscope it appears
to be made up of a vast number of nerve fibres, exhibiting an axis
cylinder, as a central dot, surrounded by a lighter substance, the
medullary sheath.

The gray substance of the spinal cord is centrally located, and
appears in the form of the letter H — i. e., two irregular bands con-
nected by a bridge. The bridge consists of the anterior gray com*
missure and the posterior gray commissure. Between the two com-
missures is the central canal. This extends through the cord longi-
tudinally, and is lined with ciliated epithelium. It is about 1mm
in diameter. The commissures consist of fibres derived from the
commissure cells. The white commissure is immediately in front of
the anterior gray commissure. Each lateral column of the gray
substance consists of three well-marked divisions — the anterior,
posterior, and lateral cornua. From the anterior cornua emerge the
anterior roots, while the posterior roots enter the posterior cornua.
The reticular process, column of Clark, and the substantia gela-*
tinosa enter into the structure of a posterior cornu. The reticular
process is a net-like mass of gray substance at the base of the cornu.
The column of Clark is on the median side, near the gray com-
missure. The substantia gelatinosa covers the horn and immedi-
ately surrounds the central canal. The substantia gelatinosa Neuro-
landi; zona spongiosa, and zona terminalis are also found in the
posterior cornu.

84 NORMAL HISTOLOGY.

In its intimate structure the gray matter consists of multipolar
cells, neuroglia, and medullated fibres. The multipolar cells are of
two kinds — motor cells and column cells. The motor cell has a
large body with long protoplasmic processes, the dendrites, and an
axis cylinder, which, emerging from the anterior cornu, becomes in-
vested with a medullary sheath, thus producing the axis cylinder
of a nerve fibre. The fibres of the anterior roots originate from the
motor cells. The column cells are smaller than those of the motor
type and have fewer dendrites. The axis cylinders from these cells
largely make up the white substance of the cord. The axis cylinders
of column cells send out many collaterals which penetrate the gray
matter. After entering the white matter, each cylinder divides into
two stem-fibres, ascending and descending, which extend longitudi-
nally through the cord, giving off many collaterals, which return
to the gray matter and terminate in tufts of fibrils, the stem-fibres
eventually terminating in the same way. The axis cylinders which
originate in Clark's column do not divide when they^ reach the white
substance, as do those of the column cells, but proceed upward to
the cerebellum.

The supporting framework of the gray matter consists of neu-
roglia, which is composed of gliq cells and their processes. There
are two kinds of glia cells — the ependymal cells and Deiter's cells.
Ependymal cells are of the epithelial type and line the lumen of the
central canal. They are provided with cilia and send out processes
into the surrounding tissues. Deiter's cells are found in the gray
matter, and afterwards in the white. They send out delicate proc-
esses, which form a supporting framework for the delicate nerve
structures.

The investments of the spinal cord are the dura mater, on the
outside; the arachnoid membrane, centrally located; and the pia
mater, immediately surrounding the cord. From the pia mater,
septa of connective tissue extend inward.

There are thirty-one pairs of nerves springing from the spinal
cord. The motor nerves are anterior, while the sensory nerves are
posterior. These nerves are distributed to the muscles, skin, a^d
other parts of the body, where they are provided with special ter-
minations adapted to receive impressions.

NERVOUS TISSUES AND SYSTEMS. 85

BRAIN.

The brain comprises the medulla oblongata, the cerebellum, and
the cerebrum. It is directly connected with the spinal cord, and,
thus, with the nerve structures of all parts of the body. It sends
forth twelve pairs of cranial nerves, which supply the organs of
sense, lungs, heart, etc. It possesses two kinds of nervous mat-
ter, gray and white. The arrangement of these substances is the re-
verse of that exhibited in the spinal cord, except that in the me-
dulla oblongata the gray matter is centrally located. The gray mat-
ter is found in the cerebral cortex, the corpora striata, optic thai ami,
corpora quadrigemina, cerebral ganglia, the lining of the ventrielos,
and the cerebellar cortex.

The whole brain is encased with three characteristic membranes,
the dura mater on the outside, next to this the arachnoid membrane,
and on the inside, immediately investing the brain, the pia mater.

The dura mater is a dense, elastic, fibrous membrane. It sends
three processes into the brain for its protection and support, and also
penetrates the skull. The arachnoid membrane lies between the
dura and pia, and is extremely thin and delicate. Between the
arachnoid and pia is a space filled with the cerebro-spinal fluid. The
membrane is composed of white fibres and elastic tissue. The pia
mater consists of a plexus of blood vessels held together by delicate
areolar tissue.

OUTLINE OF THE BRAIN.

Medulla ob-
longata

Anterior median.
Fissures. . . . \ Posterior median.

Two lateral fissures.

Anterior.
Surfaces ..A Lateral.

Posterior.
f White matter.

Substances. •{

[_ Gray matter.

f Cerebellar f Molecular layer.

n , ,, cortex . . . < Layer of Purkinji's cells.

Cerebellum . . j | Granular layer.

I Medulla, or

white mat- f Medullated fibres,
ter.

Connective tissue.

86

NORMAL HISTOLOGY.

Cerebral
cortex

Cerebrum <j Medulla.

Ventricles.

Brain invest-
ments .

f Granular layer.

Layer of small pyramidal cells.
<{ Layer of large pyramidal cells.
I Layer of irregular cells.
t Layer of fusiform cells.

Medullated fibres.
Connective tissue.

f Multipolar ganglion
Gray matter.

White matter.

Medullated fibres.
Medullated fibres.
Connective tissue.

Dura mater.
Arachnoid membrane.
Pia mater.

MEDULLA OBLONGATA.

The structure of the medulla oblongata is virtually the same as
that of the spinal cord. The chief difference consists in the arrange-
ment of the structural elements.

CEREBELLUM.

The cerebellum consists of the cerebellar cortex and medulla.

The cerebcllar cortex comprises three layers — the molecular layer,
of Purkinji's cells, and granular layer. The molecular layer
is composed of large and small multipolar ganglion cells. The small
cells are disposed toward the surface. The large cortical cells are in
the deeper portion of the cortex and send out protoplasmic processes
toward the surface. Purkinji's cells are large, somewhat pear-
shaped ganglion cells, which send out two large protoplasmic proc-
esses from one pole of each cell into the molecular layer. The axis
cylinder proceeds from the opposite pole, becomes a medullated fibre,
and enters the white matter of the cerebellum. The granular layer
is the innermost, and is composed of large and small cells provi-M
with large nuclei. The whole layer presents a rusty appearance.
Each cell is provided with dendrites and a non-medullated nerve
process, which extends into the molecular layer.

NERVOUS TISSUES AND SYSTEMS. 87

The white matter consists of meduttated fibres and neuroglia.
There are two kinds of neuroglia cells in the cerebellum: First,
small rounded cells, which occur in the granule layer and send a
few processes downward and many longer processes outward to the
molecular layer; second, stellate cells, which are found in all the
layers.

CEREBKTJM.

The cerebrum comprises the cerebral cortex, medulla, and ventri-
cles.

The cerebral cortex is composed of five layers which merge im-
perceptibly into each other. They are :

( 1 ) Molecular Layer. — This is superficial, and is finely granular,
with an interlacing of medullated fibres and a reticulum of neu-
roglia. The cells of Caji are found in this layer.

(2) Layer of Small Pyramidal Cells. — This is composed of gan-
glion cells which are pyramidal in form. They send out several
apical and lateral dendrites, which penetrate the molecular layer
and, by continuous division, produce a complicated network. The
axis cylinder proceeds from the basal end of the cell and, after send-
ing out a few collaterals, enters the medulla.

(3) Layer of Large Pyramidal Cells. — This differs from the pre-
ceding in the size of its cells. The axis cylinder process enters the
medulla to become a medullated fibre.

(4) Layer of Irregular Cells. — This is composed of cells, oval or
polygonal, which are devoid of apical dendrites. Each axis cylinder
sends out collaterals and then enters the medulla to become one or
two nerve fibres.

(5) The Layer of Fusiform Cells. — This lies adjacent to the
medulla and is composed of a few spindle-shaped cells with ner^e
fibres between them. The cells are arranged parallel with the course
of the fibres.

The medulla. — This comprises the white matter of the cerebrum,
and is composed of medullated fibres and connective tissue struc-
tures.

The ventricles. — The gray matter of the ventricles, like that of
the cerebral cortex, is composed of multipolar ganglion cells, neu-

88 NORMAL HISTOLOGY.

roglia, and medullated fibres. The cells give rise to axis cylinders
which produce the cranial nerves. The white matter of the ven-
tricles consists of medullated fibres and neuroglia.

THE SYMPATHETIC NERVOUS SYSTEM.

The sympathetic system consists of a double chain of ganglia
(about twenty-four pairs) extending along the anterior portion of
the spinal column and connected together by intervening cords,
three great plexuses (cardiac in cervical region, epigastric in ab-
dominal region, and hypogastric in pelvic region), smaller ganglia,
and many non-medullated nerve fibres. The nerve fibres are of two
kinds — communicating and distributory. They are non-medullated,
and by some authorities are supposed to be without a neurilemma.

TERMINAL NERVOUS SYSTEM.

The peculiar modifications of nerve endings may appropriately
be considered as constituting a third nervous system, the terminal
system, often styled the peripheral system.

Every nerve has central and peripheral terminations. The cen-
tral ending is in the cell with which it originates. There are three
important varieties of peripheral endings for sensory nerve fibres — •
viz., free nerve endings, terminal corpuscles, and neuro-epithelial
cells.

1. Free nerve endings occur in the skin, mouth, cornea, and
spinal cord. By this method the nerve fibre loses its neurilemma
and medullary sheath, and the axis cylinder breaks up into deli-
cate fibrils, which sometimes anastomose with each other. In the
skin the fibrils are confined to the stratum Malpighii.

2. Terminal corpuscles occur in the skin. Stirling and Piersol
give four kinds of peripheral corpuscles — (1) simple tactile cells,
(2) compound tactile cells, (3) end bulbs, (4) touch corpuscles.

Simple tactile cells occur in the stratum Malpighii. The fibre
breaks up into fibrils by the usual method, but each fibril terminates
in a tactile disk, above which lies the tactile cell.

In compound tactile cells, the tactile disk forming the termination
of the axis cylinder lies between two tactile cells.

End bulbs occur in mucous membranes, the cutis, and other

NERVOUS TISSUES ANE SYSTEMS. 89

places. The bulbs vary in shape, round to cylindrical, and consist
of a fibrous capsule and a central core in which terminates an axis
cylinder. The Pacinian corpuscle, which occurs in the subcutaneous
tissue of certain localities, is a variety of the same and is peculiar in
exhibiting many concentric fibrous Iamina3.

Touch, corpuscles occur in the papillae of the skin. The nerve
fibre as it enters the corpuscle breaks up into fibrils, which form a
coil, giving a striated appearance.

3. Nemo-epithelium. — This occurs in the perceptive organs and
consists of highly specialized cells, such as the rod and cone cells of
the retina, and olfactory and gustatory cells. These cells receive
the stimuli from external sources, the nerve-fibres conveying them
onward to the. nerve centers.

Laboratory exercise No. 24. — The spinal cord. Harden pieces of the
spinal cord of a cat in Muller's fluid, embed in paraffin, and stain with
hsematoxylin and eosin, method No. 8. Examine first with L. P., then
with H. P. Study the structure of the inclosing membranes. Observe
the septa of connective tissue extending- from the pia mater into the
underlying tissue. Find the posterior median septum, and the anterior
median fissure. How can you always distinguish the posterior from
the anterior surface of the cord? Note the difference in appearance
between the white matter and gray matter. Make a study of the white
matter, noting the axis cylinders with their medullary sheaths. Find
the posterior and anterior lateral columns. Make a study of the gray
matter, observing the anterior and posterior lateral cornua. Look for
the anterior and posterior roots of the spinal nerves. Observe the cen-
tral commissure inclosing the central canal. Multipolar ganglion cells
should be found in the gray matter. Follow out an axis cylinder until
it enters the white matter. Look for neuroglia. Drawings.

Laboratory exercise No. 25. — The cerebrum. Harden in Muller's fluid,
embed in paraffin, and stain with ha3matoxylin and eosin, method No. 8.
In examining the cerebrum, search first for the pia mater; then demon-
strate the cerebral cortex with its five layers made up of cells of differ-
ent forms and sizes; and, finally, the medulla, consisting chiefly of me-
dullated fibres. The layers of the cerebral cortex, beginning externally,
will be arranged in the following order: Granular layer, layer of small
pyramidal cells, layer of large pyramidal cells, layer of polymorphous
cells, and the layer of fusiform cells. Demonstrate the axis cylinders
and their collaterals; observe the bundles of medullary fibres extend-
ing between the cells. Drawings.

Laboratory exercise No. 26. — The cerebellum. Harden in Muller's
fluid, embed in paraffin, and stain with haBmatoxylin and eosin, method

90 NORMAL HISTOLOGY.

No. 8. An examination of the cerebellar cortex will exhibit three layers
— the molecular layer, the layer of Purkinji's cells, and the granular
layer, located internally. The white matter will be found to be made
up of medullated fibres and neuroglia. Observe the primary and sec-
ondary convolutions. Notice the cells of Purkinji and their proto-
plasmic processes. Note also the pia mater. Drawings.

NERVOUS TISSUE.

A. Cells. B. Fibres.

A. Cells: (a) Neuroblast; (b) Neuron; (c) Neuro-dendron ; (d) Unipolar cell;
(e) Bipolar cell; (f) Multipolar cell; (g) First-type cell; (h) Second-type cell; (i)
G-liacell; (j) Axis cylinder process; (k) Collaterals; (1) Dendrites.

B. Fibre: (a) Neurilemma; (b) Medullary sheath; (c) Axilemma; (d) Axis cyl-
inder; (e) Nodes of Ranvier; (f) Internode: (g) Nerve corpuscle.

C. Q-anglion, exhibiting cells and fibres and sheath.

D. Nerve: (a) Fibres; (b) Epineurium; (c) Perineurium; (d) Endoneurium.

Spinal Cord.

Spinal cord: (a) Pia mater; (b) Septa; (c) Anterior median fissure; (d) Poste-
rior median fissure; (e) Anterior lateral column; (f) Posterior lateral column; (g)
Column of Q-oll; (h) Column of Burdoch; (i) Anterior gray commissure; (j) Poste-
rior gray commissure ; (k) Central canal; (1) Anterior Cornu; (m) Posterior Cornu;
(n) Lateral Cornu; (o) Motor cells; (p) Column cells; (q) Neuroglia.

NERVOUS TISSUE.

Cerebrum.

Cerebrum: (a) Dura mater; (b) Arachnoid; (c)Pia mater; (d) Septa; (e) Cere-
bral cortex; (f) Medulla; (g) Molecular layer; (h) Layer of small pyramidal cells;
(i) Large pyramidal cells; (j) Layer of irregular cells; (k) Layer of fusiform cells;
(1) Medullated fibres; (m) Axis cylinder; (n) Neuroglia.

Cerebellum.

Cerebellum: (a) Pia mater; (b) Cerebellar cortex; (c) Molecular layer; (d)
Layer of Purkinji's cells; (e) Granular layer; (f) Medulla; (g) Medullated fibres;
(h) Neuroglia; (i) Primary convolutions; (j) Secondary convolutions; (k) Pur-
kinji's cells and processes.

[91]

NORMAL HISTOLOGY.

CHAPTER XI.

THE CIRCULATORY SYSTEM.

The circulatory system includes the heart, arteries, veins, and
capillaries. It is derived from the mesoderm of the embryo. Its
nervous supply is received from the sympathetic system. The fol-
lowing outline exhibits the structural elements which enter into
its various organs :

OUTLINE OF CIRCULATORY SYSTEM.

Heart

r Layers .

,

Annul!
fibrosi. 1,

Arteries

Veins

Cavities . . .

Valves

Tunica ad-
ventia. . .

Tunica me-
dia. .

Tunica in-
tima . .

Visceral endo-
thelium.

Pericardium <j Fibrous tissue.

| Areolar tissue.
[ Parietal endo-

thelium.

Muscular layer, or
myocardium •{ Striated fibres.

Endocardium. .

Auricles.
Ventricles.

Elastic fibres.
Substantia pro-

pria.
Endothelium.

Tunica ad-
ventia. .

Tunica me-
dia..

Tunica in-
tima . .

( Fibrous connective tissue.
( Endocardium.

j Fibrous connective tissue.
( Elastic fibres.

j Involuntary muscle.
( Elastic tissue.

T Internal elastic membrane.
< Sub-endothelial tissue.
I Endothelium.

f Connective tissue.
<j Elastic fibres.
^ Smooth muscle.

f Involuntary muscle.
I Elastic tissue.

{Internal elastic membrane.
Sub-endothelial tissue.
Endothelium.
Valves.

THE CIRCULATORY SYSTEM. 93

Capillaries 4 Cement

[ Sti

f Endothelial cells.
Cement.
Stigmata.

THE HEART.

The heart is composed of three distinct layers — pericardium;
muscular layer, or myocardium; and endocardium.

The pericardium is lined on its outer and inner surfaces with a
single layer of endothelium. Between these layers are fibrous and
areolar tissues, which send out septa into the myocardium.

The muscular layer, or myocardium, is composed of striated
fibres which branch, and the branches anastamose with each other.
The fibres run in all directions, interweaving with each other, thus
making possible the peculiar contraction of the heart. The fibre is
without a sarcolemma and has centrally-located nuclei.

The endocardium, or inner layer, is composed of elastic fibres,
the substance proper, and endothelium. The substance proper con-
tains smooth muscle fibres, which are surrounded by a delicate peri-
mysium.

The annuli fibrosi consist of ligaments which lie between the
auricles and ventricles, and form an attachment for numerous
muscle fibres.

The valves of the heart are modified endocardium. They consist
of endocardium and fibrous connective tissue which is continuous
with that of the annuli fibrosi.

THE ARTERIES.

Arteries comprise three coats — Tunica adventitia, tunica media,
and tunica intima. The tunica adventitia is the external layer and
consists of bundles of connective tissue and elastic fibres, longitudi-
nally disposed. The tunica media is composed of involuntary mus-
cle ancl elastic tissue, circularly disposed. The tunica intima con-
sists of the internal elastic membrane, which is structureless in
character ; the subendothelial tissue, which consists of flattened cor-
puscles and elastic fibres ; and the endothelium, consisting of a sin-
gle layer of cells lining the internal cavity of the artery.

94 NORMAL HISTOLOGY.

VEINS.

A vein also consists of three coats similarly named to those of
the artery. A vein differs from an artery in being thinner, and in
having a preponderance of connective over muscular and elastic tis-
sues.

The tunica adventitia is composed of bundles of connective tissue,
elastic fibres, and involuntary muscle, which intercross, the general
arrangement being longitudinal. In the tunica media, the smooth
muscle fibres are circularly arranged and are associated with fibro-
elastic tissue. The tunica intima comprises the internal elastic
membrane, the subendothelial tissue, and a single layer of polyhe-
dral endothelial cells.

The valves of the veins are produced by an infolding of the in-
tima. Their surfaces are lined with endothelial cells.

CAPILLARIES.

A capillary consists of a single layer of endothelial cells united
to each other by a cement substance and exhibits at intervals open
spaces, the stigmata. It is through the stigmata that the leucocytes
migrate on their mission to build up the worn-out tissues of the
body. Capillaries which supply nutrition to blood-vessels are called
vasa vasorum. The diameter of a capillary averages about 8 /*.

Laboratory exercise No. 27. — The heart. Fix and harden with alco-
hols, embed in paraffin, and stain with haematoxylin, method No. 6.
In examining your preparation, search first for the pericardium, and
demonstrate its endothelial lining- and fibrous connective tissue; then
examine the myocardium, observing the course of the fibres, their
branching and anastomosing, and the centrally located nuclei; finally,
examine the endocardium, composed of fibrous tissue, elastic fibres,
and endothelium. If possible, examine the structure of a valve. Search
for blood-vessels. Drawings.

Laboratory exercise No. 28. — Arteries and veins. Harden the great
aorta in alcohol, embed in paraffin, and stain with haematoxylin and
eosin, method No. 8. Examine with H. P. and make out the three coats
— the tunica adventitia on the outside, tunica media in the middle, and
tunica intima on the inside. Name the structures which enter into
these coats. A study of veins may be made from sections of the um-
bilical cord, the lungs, or the tongue. Drawings.

CIRCULATORY SYSTEM.

Heart.

Heart: (a) Pericardium, exhibiting endothelial layers and intervening fibrous
tissue; (b) Myocardium: (c) Endocardium, with its elastic fibres, substantia pro-
pria and endothelium; (d) Annuli flbrosi; (e) Anastomosing striated fibres; (f)
Nucleus; (g) Valve.

A. Artery. B. 'Capillary and Vein.

A. Artery: (a) Tunica adventitia; (b) Tunica media: (c) Tunica intima.

B. Vein : (a) Tunica adventia; (b) Tunica media; (c) Tunica intima; (d)
Capillary.

[95]

96

NORMAL HISTOLOGY.

CHAPTER XII.

THE LYMPHATIC SYSTEM.

The lymphatic system includes lymphatic tissues, vessels, organs.
Lymphatic tissue is immediately concerned in the production of
lymph corpuscles. The yellowish fluid contained in the lymphatic
vessels is the lymph. The structures of this system are derived from
the epiderm and mesoderm.

OUTLINE OF THE LYMPHATIC SYSTEM.

Lymphatic tissue . .

Lymphatic vessels.

Adenoid tissue, or connective tissue reticulum.
Lymphoid cells.

Outer coat.
Middle coat.
Inner coat.

( Simple nodules ,

Lymphatic follicles •{

f Capsule.

[ Adenoid tissue and lym-
phoid cells.

f Capsule and trabeculae.

f Corticalfollicles.

Compound lymphatic
follicles

Cortex

I Germinal center.

Medulla.
Hilum.
Sinuses.
Reticulum.

Spleen .

Capsule

Splenic
pulp. .

Derivation

Thymus body <j Capsule.

Lobes . . .

Serous coat.
Fibrous coat.
Trabeculse.

[ Lobes...]

Divisions .

Structure

Septa.
Lobules . .

Loose adenoid tissue.

Dense adenoid tissue, or
Malpighian corpuscles.

Connective tissue reticu-
lum.

{Leucocytes.
Red corpuscles.
Lymphoid cells.
Pigment granules.

Cortex.

Medulla.

Hassal's corpuscles.

THE LYMPHATIC SYSTEM. 97

f Capsule.
Adenoid tissue.

Tonsils Mucous g-lands.

[ Blood and lymph corpuscles.

LYMPHATIC TISSUE.

Lymphatic tissue is composed chiefly of two structures: (1) A
connective tissue reticulum. This is commonly known as adenoid,
or retiform tissue. (2) The lymphoid cells, which are held in the
meshes of the reticulum. These escape into the lymphatic vessels
and are there known as the lymph corpuscles. They eventually
become the leucocytes of the blood.

LYMPHATIC VESSELS.

The lymphatic vessels are irregular in outline, due to folds in
the endothelium, which serve as imperfect valves. The wall of each
vepsel exhibits three coats. The inner coat consists of endothelium,
the middle of smooth muscle, and the outer of connective tissue.

LYMPHATIC FOLLICLES.

These have been classified as simple .nodules and compound lym-
phatic nodes. The simple nodule consists of a capsule and adenoid
tissue with enclosed lymphoid cells. The compound lymphatic
node exhibits capsule, reticulum of connective tissue, cortex, and
medulla. The capsule is the sheath of connective tissue which cov-
ers the node and from which septa, or trabeculas, extend into its
substance. The cortex is the outer zone of the body, and consists
of the cortical follicles and the germinal center. The cortical folli-
cles are the laboratories in which are manufactured the leucocytes.
The germinal center is a light spot within the follicle, characterized
by the presence of kinetic figures. The medulla is the central por-
tion of the gland. It contains the medullary bands, which are sim-
ply extensions of the trabeculae into its substance. TJhis mesh- work
formed by the subdivision of the trabeculae constitutes the reticulum.
The Jiilum is an infolding of the capsule upon a blood-vessel or
lymph channel at its point of entrance into the gland. Sinuses are
the open spaces between the adenoid tissue and trabeculae.

98 NORMAL HISTOLOGY.

THE SPLEEN.

The spleen has the structure of a large lymphatic node. It con-
sists of a capsule and splenic pulp. The capsule consists of two
coats — an outer serous and inner fibrous coat. Extending from
the capsule into the piilp are trabeculw, which divide and subdi-
vide, forming a reticulum of connective tissue. The splenic pulp
comprises the loose adenoid tissue and the dense adenoid tissue. The
dense adenoid tissue is disposed in spherical masses which are situ-
ated in the forks of the arteries. Each mass is pierced by an ar-
tery. These dense spherical masses of the pulp are called Malpighi-
an corpuscles. Their structure does not differ materially from that
of the loose tissue. The pulp, as with other lymphatic structures,
consists of a connective tissue reticulum, holding in its meshes leu-
cocytes, red corpuscles, lymph oid cells, and pigment granules.

THYMUS BODY.

This structure is derived from the hypoderm, and in its early
development is chiefly epithelial in character, but later becomes in-
vaded with mesodermic tissues, until it assumes a lymphatic type.
After the second }rear it loses its characteristic structure, and its
tissues are replaced by fibrous tissue and fat. It consists of a cap-
sule and a pulp, which is divided into lobes. The lobes are separated
from each other by septa derived from the capsule. The lobes are
divided into lobules, each lobule consisting of adenoid tissue, the
outer, looser portion being called the cortex, while the inner, denser
portion is the medulla. Hassal's corpuscles are masses of em-
bryonic epithelial cells found in the medulla,

TONSILS.

The tonsils are composed of diffuse adenoid tissue, containing
from ten to eighteen lymph follicles. There is a fibrous capsule, be-
neath which are the connective tissue reticulum, the lymphatic fol-
licles, mucous glands between the follicles, and lymphoid cells.

Laboratory exercise No. 29.— The spleen. Harden in Erlicki's fluid
or alcohol, embed in paraffin, and stain with haematoxylin and eosin,
method No. 8. Examine, first, the capsule, and its extensions, or tra-
beculae, penetrating the splenic pulp. Distinguish between the loose
and dense adenoid tissue. Examine the structure of a Malpighian cor-
puscle with H. P., noting the connective tissue reticulum and the
lymphoid cells. Describe the disposition of arteries, veins, and lym-
phatics in the spleen. Has the spleen a duct? Drawings.

LYMPHATIC SYSTEM.

Lymphatic Follicle.

Compound lymphatic node: (a) Capsule; (b) Cortex; (c) Cortical follicle; (d)
Germinal center; (e)Mudulla; (f) Hilum; (g) Sinus; (h) Reticulum; (i) Lymphoid
cells.

Spleen.

Spleen: (a) Capsule— serous coat; (b) Fibrous coat; (c) Trabecula; (d) Loose
adenoid tissue; (e) Malpighian corpuscle; (f) Reticulum; (g) Lymphoid cells;
(h) Leucocytes; (i) Blood vessels.

[99]

100 NORMAL HISTOLOGY.

CHAPTEE XIII.

MEMBRANES AND GLANDS.
I. MEMBRANES.

Membranes are disposed upon surfaces in the interior of the body.

OUTLINE OF MEMBRANES.

f Serous membranes proper.

I
Serous membranes -{ Synovial membranes.

Endothelium.
Epithelium.

Mucous membranes

Basement membrane.

( Fibrous connective tissue.
Stroma .......... <J

t Elastic fibers.
Muscular is mucosee.

p .-,•,

(_ Occasional structures ....... <J Glands.

{ Lymphoid cells.

There are two kinds of membranes — serous and mucous. Serous
membranes cover the outside surfaces of the alimentary tract and
respiratory organs, as well as the articular ends of bones and other
structures. They include three varieties — serous membranes proper,
synovial membranes, and endothelium. Serous membranes proper
are composed of fibrous tissue and elastic fibres, with a superficial
layer of endothelium. Synovial membranes include the capsules
which envelop the ends of joints and the sheaths in which tendons
glide. They are characterized by the viscid fluid — the synovia —
which they secrete. Endothelium consists of a single layer of flat-
tened endothelial cells.

Mucous membranes line all surfaces which are directly or indi-
rectly in communication with the external atmosphere. The struc-
ture of the mucous membrane exhibits the following elements:
(1) The epithelium. This may be simple or stratified. It may be
squamous, columnar, or ciliated. Columnar and ciliated epithelia

MEMBRANES AND GLANDS. 101

are usually provided with goblet cells, whose function is to produce
mucus. With squamous stratified epithelium,, the mucus is usually
produced by glands located in the stroma, (2) Basement mem-
brane. This occurs as a mere line beneath the epithelial layer. It
is sometimes called the membrana propria, It is made up of flat-
tened cells, either united edge to edge, or held together by anasta-
mosing processes. On one side, this membrane supports the epithe-
lium ; while on the other, it is in close connection with the capil-
laries. (3) The stroma. This structure lies directly beneath the
basement membrane, and is composed of fibrous connective tissue
and elastic fibres, and is provided with a rich supply of blood-vessels
and lymphatics. (4) The Muscularis mucosce. This is a shallow,
muscular sheath, which forms the lower limit of the mucous
membrane. It is composed of circular and longitudinal strata
of involuntary muscle fibres. (5) Occasional structures. In. addi-
tion to the structures above named, papilla?, villi, glands, and lym-
phoid cells occur in the mucous membrane. Papillce are conical ele-
vations of the stroma, which are supplied with blood-vessels and
nerves, and covered with epithelium. They occur in the tongue,
oesophagus, etc. The villi occur chiefly in the small intestine.
They are provided with blood capillaries and lacteals, and are de-
signed to increase the absorbing surface of the intestine. The
glands which occur are of two varieties — tubular and sacular. The
mucous glands are located in the epithelial layer and stroma of
mucous membranes, and are concerned in the elaboration of mucin.

IT. GLANDS.

Glands are of two kinds — serous and mucous. A serous gland is
characterized by spherical, granular cells, with central nuclei, which
are readily stained by carmine. Mucous glands are not readily
stained by carmine. The nuclei are usually upon the cell surface.

OUTLINE OF GLANDS.

f Serous glands.

Kinds \

[ Mucous glands.

102 NOKMAL HISTOLOGY.

f Simple.

(Tubular. . .. <
{ Compound.
f Simple.

^ Saccular <

[ Compound, or race-
mose.

(Basement membrane.
Secretory cells.
Structure . . . <j Lumen.

Duct.
Development.

There are two characteristic forms of glands — tubular and sac-
ular — either of which may be simple or. compound. A simple tu-
bular gland is cylindrical and elongated/ consisting of a basement
membrane lined internally with cuboidal or columnar cells which
constitute the fundus, the opening from the gland being styled the
duct. The empty space within the gland is the lumen. When the
lumen becomes divided by one or more partitions,, producing a clus-
ter of simple glands, we then have a compound tubular gland. The
saccular gland resembles in structure that of the tubular variety, but
in form it is broader, becoming inflated like a sac. A group of
simple saccular glands gives rise to the compound saccular, or race-
mose, variety. The chief function of glands is that of secretion.
The salivary glands, pancreas, and intestinal glands are illustra-
tions.

III. PAROTID GLAND.

The Parotid gland is a compound saccular gland of the serous
type. Its tissues are derived from the mesoderm and epiderm. Its
function is to produce saliva, a watery substance containing mi-
nute granules.

OUTLINE OF THE PAROTID GLAND.

f Secretory cells.
Acini. Basement mem-

Ductules.

Lobes <! Connective tissue.

Stenson's duct.
Ducts

Salivary tubes.

MEMBRANES AND GLANDS. 103

Structure, — There is an investing capsule of fibrous connective
tissue which sends out septa into the substance of the gland; these
septa divide the gland into lobes and lobules. Each lobule is com-
posed of acini, each acinus consisting of a basement membrane lined
with secreting cells. The lumen of the acinus, or alveolus, leads to
the alveolar ductule, the ductules discharging into the salivary
tubes; the salivary tubes into the intermediate tubes; and these into
Stenson's duct, which is the large excretory duct. Stenson's duct is
composed of fibro-elastic tissue lined internally with a single layer
of columnar epithelium.

Laboratory exercise No. 30. — Parotid gland. Harden in alcohol, em-
bed in paraffin, and stain with carmine, method No. 3. It is well in
demonstrating- most structures to begin with the external, simpler
parts, and work inward to those that are more complex. In this case
demonstrate first the capsule and its penetrating1 septa. Note how the
giand is diyided into lobes and lobules by the subdividing- septa. Ob-
serve an acinus, and note the form of the cell. Find Stenson's duct and
note its structure. Drawings.

IV. THE PANCREAS.

The pancreas is a compound tubular giand of the serous type.
The following outline exhibits its structure:

OUTLINE OF THE PANCREAS.

Capsule.
Septa.

f Acini.

Lobes < Gland cells.

{ Bodies of Langerhans.
Pancreatic Duct.

Intermediate tubules.

Structure, — The pancreas has the usual investing capsule of con-
nective tissue, from which extend numerous septa dividing the or-
gan into lobes. The lobes consist of acini, whose basement mem-
branes are lined with short cylindrical or conical cells. Each
cell is characterized by two zones — a clear peripheral zone contain-
ing the nucleus, and the zone next the lumen which contains the
so-called zymogen granules. The bodies of Langerhans are imper-

104: NORMAL HISTOLOGY.

feet acini which appear as less dense rounded areas among the ordi-
nary tissue. For the elimination of the products of secretion, the
pancreas is provided with ductules, intermediate tubules, and the
pancreatic duct. The last is composed of fibrous connective tissue
lined internally with epithelium and provided with minute mucoas
glands.

Laboratory exercise No. 31. — Pancreas. Harden with alcohol, embed
in paraffin, and stain with carmine. Make out the following structures:
The capsule, septa, lobes, acini, basement membrane, secretory cells,
containing nuclei and granules, intermediate tubules, and pancreatic
duct. Drawings.

MEMORANDA.

GLANDS.

Forms of Glands.

A. Simple tubular gland: (a) Basement membrane; (b) Secretory cells; (c)
Lumen; (d) Duct.

B. Compound tubular gland: (a) Basement membrane; (b) Cells; (c) Duct-
ule; (d) Duct.

C. Simple saccular gland.

D. Compound saccular gland.

A. Parotid Gland. B. Pancreas.

A. Parotid gland: (a) Capsule; (b) Septa; (c) Lobe; (d) Lobule; (e) Acinus;
(f) Secretory cells; (g) Basement membrane; (h) Lumen; (i)Ductule; (j)Stenson's
duct; (k) Connective tissue.

B. Pancreas: (a) Capsule; (b) Septa; (c) Lobe; (d) Acinus; (e) Gland cells;
(f) Bodies of Langerhans; (g) Pancreatic duct; (h) Intermediate tubules.

[105]

106

NORMAL HISTOLOGY.

CHAPTEK XIV.

THE SKIN.

The epidermis of the skin is derived from the epiderm of the
embryo, while the corium is largely of mesodermic origin. Its chief
functions are protection, respiration, and excretion.

OUTLINE OF SKIN.

Derivation.

Structure

Epidermis

Stratum corneum.
Stratum lucidum.
Stratum granulosum.
Stratum malpighii. . . .

Pigment granules.
Prickle cells.

Appendages

Coriuni

Glands

Nails

f Fibrous connective tissue.
. . . . •) Elastic fibres.

L Blood vessels, nerves, etc.

{Sebaceous.

Sudoriferous.

( Body

j Free edge.

1 Nail wall.

. . { Root . .

\ Nail fold.

Nail bed.
Matrix.

Cuticle.
Shaft <! Cortex.

Medulla.

{ Bulb.

Root <| Papilla.

I Follicle.

Structure, — The skin consists of two layers — the epidermis, or
cuticle, and corium, or cutis. The epidermis is constituted of strati-
fied squamous epithelium disposed in four layers. These are the
stratum corneum, stratum lucidum, stratum granulosum, and
stratum Malpighii. The stratum corneum is superficial and is com-
posed of flattened corneous cells which have lost their protoplasm
and, by desquamation, are continually cast off. The stratum luci-
dum, occurs next, and comprises a narrow zone in which the cells
exhibit an approach to the flattened scales of the outer stratum.

THE SKIN. 107

The stratum granulosum contains cells more flattened than those of
the succeeding layer, and possesses granular particles, called eleidin,
which have an affinity for carmine. In the stratum, Malpighii, the
cells are rounded, or even columnar, in shape. Some of the cells
are connected by protoplasmic processes, which give rise to the so-
called prickle cells. In this layer occur the pigment granules that
give color to the skin. Beneath the epidermis is a basement mem-
brane. The corium comprises all that part of the skin underlying
the epidermis. It consists of two layers — the stratum papillare and
the stratum reticulare. The stratum papillare contains the papillae,
which are conical elevations of the corium into the epidermis. They
are supplied with blood-vessels and nerves, a nerve-ending occurring
at the summit of each papilla. The corium is composed of fibrous
connective tissue, elastic fibres, blood-vessels, nerves, glands, and a
small amount of muscular tissue. The sebaceous glands are lo-
cated in the corium papillare, while the sudoriferous glands occur
in the corium reticulare or subcutaneous tissue. The corium rests
upon a subcutaneous structure, which consists chiefly of areolar,
adipose, and fibrous connective tissues.

APPENDAGES.

The nails. — Nails are derived from the epidermis, and are com-
posed of horny cells. The structure of the nail comprises the body,
root, nail-bed, and matrix. The body, or exposed part, terminates
in a free-edge, while its sides are protected by the nail- walls. The
groove which receives the root is the nail-fold. That portion of the
epidermis upon which the nail rests is the nail-bed, and the basal
portion of the nail-bed upon which the root rests is the matrix. The
matrix and nail-bed are constituted of the stratum Malpighii, while
the body and root represent the stratum lucidum, the stratum cor-
neum being absent. The portion which is actively engaged in pro-
ducing the nail-body is the matrix. The nail, therefore, grows in
length, thickness, and width by the formation of new cells by the
matrix. The body consists of horny plates.

The hair. — Hair is a modification of the epidermis, and is pro-
duced by an infolding of the epidermis and a differentiation of the
lower cells of the follicle thus produced. The hair consists of two

108 NORMAL HISTOLOGY.

parts, the shaft and the root. The shaft comprises the cuticle, or
outer, imbricated layer of epithelial cells ; the cortex, or middle lay-
er, composed of elongated, horny, epithelial cells, which contain
the pigment granules that give color to the hair; and the medulla.
which constitutes the central cylinder and is composed of cuboidal
cells filled with minute air vesicles which appear as dark granules.
These air vesicles also contribute to the color of the hair. The
follicle is the receptacle of the hair, produced by the infolding of
the epidermis. Above the sebaceous glands it consists of a fibrous
coat, stratum lucidum, and stratum corneum, but beneath them the
stratum corneum disappears. The root and bulb of the hair exhibit
a continuation of the same essential structures as found in the shaft.
The papilla is a conical elevation of the corium into the base of the
follicle and hair bulb. It contains pigment cells and blood-vessels,
which provide nourishment.

A transverse section of a hair varies in outline with different
races. The hair of the Mongolian (Japanese) exhibits a circular
outline ; that of a German is oval ; that of a Negro is flattened-ovate ;
while that of the Papuan is still more flattened and crescent-shaped.
The hair is provided with sebaceous glands, which are of the simple
and compound saccular type. These open into the hair follicles near
their upper extremity. The sebum, or secretion, which they dis-
charge upon the surface of the hair is designed to oil it and keep it
in a healthy condition. Each hair is also provided with a muscle,
ihearrector pili (composed of smooth muscle fibre), which extends
obliquely from the deeper portion of the follicle to the upper por-
tion of the corium.

Sebaceus glands. — These are of the simple or compound sac-
cular type, and are located in the stratum papillare of the corium.
They consist of acini, with secreting cells, and a short duct.

The sudoriferous glands. — The sweat glands are of the simple
tubular variety. The coil of the gland is located in the subcu-
taneous tissue, and consists of a basement membrane lined with se-
creting cells. The excretory duct extends through the corium and
epidermis by a sinuous course until it reaches the stratum corneum,
when it becomes spiral, terminating upon the surface of the skin
in a rounded pit.

THE SKIN. 109

Laboratory exercise No. 32. — The skin. Harden portions of the scalp
and palm of the hand in alcohol, embed in paraffin, and stain with
haematoxylin and eosin, method No. 8. Make a study of the structures
described above, noting1 especially the stratum corneum, stratum luci-
dum, stratum granulosum, and stratum Malpigiiii of the epidermis.
Observe the membrana propria which forms a supporting- base for the
squamous cells. Note the difference in form of the cells of the different
layers. In the corium, observe the conical elevations, or papillae, and
the hair follicles which extend into its structures. The corium is made
up chiefly of connective tissue filled with blood-vessels and nerves. In
the subcutaneous tissue, search for sweat glands and trace the excre-
tory duct to the surface. Make a study of the hair, both T.S. and L.S.,
and demonstrate the shaft, root, bulb, papilla, hair follicle, cuticle, cor-
tex, and medulla. Drawing's.

MEMORANDA.

THE SKIN AND ITS APPENDAGES.

The Skin.

Skin: (a) Epidermis; (b) Stratum corneum; (c) Stratum lucidum; (d) Stratum
granulosum: (e) Stratum malpighii: (f) Prickle cells; (g) Corium; (h) Fibres of
connective tissue; (i) Blood vessels; (j) Nerve endings; (k) Papilla; (1) Sweat
gland; (m) Duct of same; (n) Subcutaneous tissue.

Hair.

Hair: (a) Follicle: (b) Shaft; (c) Cuticle; (d) Cortex; (e) Medulla; (f) Root;
(g) Bulb; (h) Papilla; (i) Sebaceous gland; (j) Hair muscle; (k) Hair of German;
(1) Hair of Negro; (m) Hair of Japanese; (n) Hair of Papuan.
[110]

NOKMAL HISTOLOGY. Ill

CHAPTEE XV.

THE ALIMENTARY CANAL.

The alimentary canal is derived from the hypoderm and meso-
derm. The squamous epithelium which lines the oesophagus is of
epidermic origin. The columnar epithelium which lines the ali-
mentary tract from the cardiac orifice onward is derived from the
hypoderm. The connective tissue and muscles of the tract are of
mesodermic origin. A careful study of the subjoined outlines will
indicate to the student the very close analogy between the different
structures of the canal. The chief differences will be found in the
pharynx and oesophagus. The upper half of the pharynx is lined
with ciliated epithelium, its lower half and the whole course of the
oesophagus being provided with stratified squamous epithelium. The
stomach and intestine have, instead, columnar epithelium. The
pharynx and oesophagus are provided with striated muscle fibre,
whereas the stomach and intestine have only smooth muscle. The
four coats which are present in all these structures are the mucosa,
sub-mucosa, muscular coat, and serous, or fibrous, coat. The mouth
is lined with stratified squamous epithelium, beneath which is the
tunica propria, or connective tissue stroma, which consists of inter-
lacing bundles of fibrous connective tissue containing elastic fibres.
There are numerous papillae in the tunica propria, and a large sup-
ply of small mucous racemose glands.

ALIMENTARY CANAL.

f Squamous epithelium.
,., ! Membrana propria.

Mucosa Stroma.

Muscularis mucosse.

Fibrous connective tissue.

Sub-mucosa <! Elastic fibres.

Glands.
(Esophagus.

f Circular muscle layer.

Muscular coat

\ Longitudinal muscle layer.
Fibrous connective tissue.

Serous coat.

Elastic fibres.

112

NORMAL HISTOLOGY.

f Mucosa.

Columnar epithelium.

Membrana propria.

Stroma.

Peptic and pyloric glands.

Muscularis mucosee.

f Connective tissue.

Stomach «{ L Vessels.

f Circular muscle layer.

Muscular coat <(

[_ Longitudinal muscle layer.

( Connective tissue.

Serous coat -j

I Endothelium.

f Columnar epithelium.
Basement membrane.
Stroma.

f Mucosa <{ Capillaries and lacteals.

Muscularis mucosse.

Villi.

Glands of Lieberkuhn.

f Connective tissue.

Sub-mucosa <| Vessel.

Small intestine. .. <{ f Brunner's glands.

(. Glands. \ Solitary glands.
[ Peyers' patches.

f Circular layer.

Muscular coat \

[ Longitudinal layer.

Serous coat.

Columnar Epithelium.
Basement membrame.
Glands of Lieberkuhn.

Muscularis mucosee.
Vessels.

Solitary glands.

Sub-mucosa <{ Peyers' patches.

Large intestine. . . •{ t Connective tissue.

f Circular layer.

Muscular coat <

1^ Longitudinal layer.

Serous coat.

THE ALIMENTARY CANAL. 113

THE (ESOPHAGUS.

The oesophagus contains four characteristic coats — the mucosa,
the sub-mucosa, the muscular coat, and the fibrous coat.

The mucosa consists of stratified squamous epithelium resting
upon a tunica propria, or connective tissue stroma, beneath which
is a thin layer of involuntary muscle, the muscularis mucosw. The
tunica propria is composed of fibrous connective tissue and contains
blood-vessels and lymphatics.

The sub-mucosa lies beneath the muscularis mucosas, and con-
sists of loose connective tissue, containing blood-vessels, nerves, and
glands of the racemose variety.

The muscular coat, in the upper end of the oesophagus, is com-
posed of striated fibres ; in the lower end, of smooth muscle ; while
the middle portion contains both smooth and striated fibres.

The fibrous coat envelops the muscular coat, contains elastic tis-
sue, and forms an attachment to the adjacent areolar tissue.

Laboratory exercise No. 33. — Tfie (Esophagus. Harden in corrosive
sublimate, embed in celloidin, and stain with carmine, method No. 3.
Examine with L. P. Demonstrate the epithelial layer, stroma and mus-
cularis mucosse of the mucosa. Search for blood-vessels, nerves, and
glands in the sub-mucosa. Examine the muscular coat, and determine
from your preparation the part of the ossophagus from which the tissue
was obtained. Note the structure of the fibrous coat. Is there an endo-
thelial layer? Do you find any investing areolar tissue?

THE STOMACH.

Tlie stomach has the usual coats — mucosa, sub-mucosa, muscular
coat, and serous coat.

The mucosa is lined superficially with a single layer of columnar
epithelium, the squamous epithelium of the oesophagus having ended
abruptly at the cardiac orifice. Besides the epithelial layer the
mucosa contains the basement membrane, the stroma, the muscularis
mucosce, and the gastric glands. The gastric glands are of two kinds
— peptic and pyloric. The peptic glands are of the simple tubular
variety, consisting of basement membrane, secreting cells, and duct.
The mouth of the duct is marked by a slight depression upon the
surface of the mucous membrane. These glands are found on the
cardiac and middle thirds of the stomach, and are provided with

114: NOKMAL HISTOLOGY.

acid cells. The pyloric glands are distributed upon the pyloric third
of the stomach and are of the compound tubular variety. They are
not provided with acid cells. They have a wide duct which leads
to the narrow lumens of the tubular branches. The stroma consists
of connective tissue supplied with capillaries and lymphatics. The
muscularis mucosw consists of a double layer of smooth muscle, an
inner circular, and an outer longitudinal.

The sub-mucosa is composed of loosely-woven bundles of elastic
tissue, containing blood-vessels and nerves. Upon its outer surface
there are alternate elevations and depressions. These give rise to
the so-called rugae and depressions of the stomach wall.

The muscular coat consists of an inner circular layer and an
outer longitudinal stratum of smooth muscle. At the cardiac end
there is also a middle oblique layer.

The serous coat consists of fibrous tissue and elastic fibres, lined
superficially with a single layer of endothelium.

Laboratory exercise No. 34. — The stomach. Fix in corrosive sublimate
solution, embed in celloidin, and stain with hsematoxylin and eosin,
method No. 8. Use H. P. and L. P. First demonstrate the four coats;
then observe the internal lining- of columnar cells with their basement
membrane. Locate and study the peptic and pyloric glands. Observe
the stroma and muscularis mucosse; also distinguish between the circu-
lar and longitudinal muscle layers. How does the serous coat differ in
appearance from the sub-mucosa? Drawings.

THE SMALL INTESTINE.

The small intestine comprises the duodenum, jejunum, and ileum.
These parts differ but slightly in general structure. There are the
four characteristic coats — mucosa, sub-mucosa, muscular coat, and
serous coat.

The mucosa consists of the following structures: (1) A single
layer of columnar epithelial cells, which cover the surfaces of conical
elevations which stud the intestine, the villi; (2) the basement
membrane, which supports the epithelium; (3) the stroma, or
tunica propria, which forms conical projections, the villi. It con-
sists chiefly of connective tissue. Each villus is supplied, superfi-
cially, with a capillary network, and through its center extends a
lacteal. (4) The muscularis mucosw consists of a longitudinal layer
with occasional circular fibres of smooth muscle.

THE ALIMENTARY CANAL. 115

The sub-mucosa consists chiefly of fibro-elastic bundles and pene-
trating blood-vessels and nerves.

The muscular coat is in two layers, an inner circular and an outer
longitudinal, separated b}r connective tissue.

The serous coat consists of connective tissue and endothelium.

There are four varieties of glands which occur in the intestinal
wall. The glands of Lieberkuhn occur in the mucosa and are dis-
tributed along the whole course of the small and large intestine,
being found between the villi. They are simple tubular depressions
provided with basement membranes and secreting cells. The
glands of Brunner are of the same type as the pyloric glands of the
stomach, but owing to repeated division they have more the appear-
ance of the compound sacular than of the tubular variety. They are
serous, and not of the mucous type. They occur in the duodenum.
The solitary glands are to be found in the sub-mucous coat and con-
sist of isolated lymph follicles. They occur in the small and large
intestines. Peyer's patches are compound glands of the racemose
variety. They occur in the mucosa and sub-mucosa. They should
be sought in the small intestine, more especially in the ileum.
Goblet cells are of frequent occurrence in the stomach and intestine.
The nerve supply of the alimentary tract is from the cranial and
sympathetic nerves.

Laboratory exercise No. 35. — Small intestine. Fix in corrosive sub-
limate, embed in celloidin, and stain with haematoxylin and eosin. Ex-
amine with L. P. and H. P., and demonstrate the following structures:
Columnar epithelium, goblet cells, membrana propria, villi, tunica
propria, capillaries, glands of Lieberkuhn, Brunner's glands, Peyer's
patches, solitary glands, muscularis mucosse, sub-mucosa, circular mus-
cle layer, longitudinal muscle layer, serous coat, and endothelium. An
injected specimen should be examined to demonstrate the capillary net-
work. Drawings.

LARGE INTESTINE.

The large intestine differs chiefly from the small intestine in
possessing thicker walls and fewer glands. It is supplied with soli-
tary follicles and the glands of Lieberkuhn, the latter containing
many goblet cells. There are the usual coats — mucosa, sub-mucosa,
muscular coat, and serous coat.

116 NORMAL HISTOLOGY.

Laboratory exercise No. 36. — Large intestine. Fix in corrosive sub-
limate, embed in celloidin or paraffin, and stain with haBmatoxylin and
eosin, method No. 8. Search for the lacteal in the center of a villus.
Demonstrate the different coats and name their structural elements.
Find the glands of Lieberkuhn and solitary follicles. Drawings. State
the functions of the various glands of the alimentary tract. How are
capillaries and lacteals distributed ? What of the nerve supply and
nerve endings?

(Esophagus.

(Esophagus: (a) Mucosa; (b) Squamous epithelium; (c) Membrana propria;
(d) Stroma; (e) Muscularis mucosae; (f) Sub-mucosa; (g) Connective tissue; (h)
Glands; (i) Circular muscle layer; ( j ) Longitudinal muscle layer; (k) Serous
coat; (1) Endothelium.

Stomach.

Stomach: (a) Mucosa; (b) Columnar epithelium; (c) Membrana propria; (d)
Stroma; (e) Peptic glands; (f) Pyloric glands; (g) Muscularis mucosae; (h) Sub-
mucosa; (i) Connective tissue; (j ) Bloodvessels; (k) Nerve; (1) Circular muscle
layer; (m) Longitudinal muscle layer; (n) Serous coat.

ALIMENTARY TRACT.

Small Intestine.

Small Intestine: (a) Mucosa; (b) Columnar epithelium; (c) Basement mem-
brane; (d)Stroma; (e)Muscularismucosse; (f)Villus; (g) Capillaries; (b) Lacteal;
(i) Gland of Lieberkuhn; (j) Sub-mucosa: (k) Connective tissue; (1) Brunner's
gland; (m) Solitary gland; (n) Peyer's patch; (o) Circular muscle layer; (p) Lon-
gitudinal muscle layer; (q) Serous coat.

Large Intestine.

Large Intestine: (a) Mucosa; (b) Columnar epithelium; (c) Basement mem-
brane; (d) Glands of Lieberkuhn; (e) Stroma; (f) Muscularis mucosse; (g) Ves-
sels; (h) Sub-mucosa; (i) Solitary gland ; (j) Peyer's Patch; (k) Connective tissue;
(1) Circular muscle layer; (m) Longitudinal muscle layer; (n) Serous coat.

[117]

118 NORMAL HISTOLOGY.

CHAPTEE XVI.
THE LIVER.

The liver is derived from the epiderm and mesoderm. It is de-
veloped as a compound tubular gland, but afterwards loses that type.
Its functions are secretion and excretion.

OUTLINE OF THE LIVER.

Investment.

Lobes. f Capsule of Glisson.

Intralobular vein.
Interlobular veins, arteries, and

Lobules •{ bile ducts.

Hepatic cells.
Bile capillaries.
^ Blood capillaries.

f Mucous membrane.

Gall cyst <{ Muscular coat.

[_ Fibrous coat.

The liver is invested with a capsule of fibrous connective tissue,
which sends prolongations into the substance of the organ, produ-
cing a framework for the support of the vessels and cells. The or-
gan is composed of lobes, and these are subdivided into lobules.
Each lobule is surrounded by a sheath of connective tissue, called
the capsule of Glisson. This capsule contains the interlobular veins
(branches of the portal vein), which send capillaries into the sub-
stance of the lobule. These converge in the center of the lobule and
form the intralobular vein, and this unites with others to form sub-
lobular veins, and these, in turn, form the hepatic vein, which con-
veys the blood from the liver. Between the capillaries are to be
found the hepatic cells, devoid of cell membranes and containing
granular protoplasm and one or two nuclei. The bile-capillaries
are between the liver cells and distinct from the blood-capillaries.
They are continuous with the interlobular bile-ducts, the latter form-
ing larger ducts which are lined with columnar epithelium. The
lobule also contains a small amount of areolar tissue. In the cap-

THE LIVER. 119

snle of Glisson, therefore, are to be found the interlobular veins,
arteries (from the hepatic artery), and bile-ducts. A thorough
knowledge of the liver lobule gives the key to a knowledge of the
whole organ.

The gall cyst, which receives the contents of the hepatic bile-duct,
is composed of mucous, muscular, and fibrous coats The larger
bile-ducts have a fibrous adventitia and a mucous membrane which,
with that of the gall cyst, is lined with columnar epithelium.

Laboratory exercise No. 37. — The liver. Harden in alcohol, embed in
paraffin, and stain with haematoxylin and eosin. Observe upon the sur-
face the fibrous investment and note the prolongations of its structure
into the interior. Focus upon a single lobule and note the following-
parts: The interlobular vein, centrally located; the network of ra-
diating blood capillaries, which is easily demonstrated in injected speci-
mens; the bile capillaries between the hepatic cells, which receive the
bile elaborated within the lobule and convey it to the larger bile ducts;
the hepatic cells, noting their form and arrangement and granular
appearance; the capsule of Glisson, containing bile ducts and branches
of the portal vein and hepatic artery. Search for bile ducts and the gall
cyst, noting their structure. Drawings.

MEMORANDA.

THE LIVER.

Liver Structures.

Liver: (a) Capsule; (b) Lobe: (c) Lobules; (d) Capsule of G-lisson; (e) Blood
•vessels; (f ) Hepatic cells.

A. Liver Lobule. B. Gall Cyst.

A. Lobule: (a) Capsule of G-lisson; (b) Interlobular vein; (c) Interlobular
arteries; (d) Interlobular bile duct; (e) Capillary network; (f) Bile capillaries;
(g) Hepatic Cells; (h) Intralobular vein.

B. Gall Cyst: (a) Mucous coat; (b) Columnar cells; (c) Muscular coat; (d)
Fibrous coat.

[120]

NORMAL HISTOLOGY.

121

CHAPTER XVII.

TONGUE AND TEETH.
I. TONGUE.

The tongue is derived from the epiderm and mesoderm. It con-
sists chiefly of a mucous membrane and bundles of muscle fibers as-
sociated with connective tissue. It is the organ of taste, this sense
being derived especially from the taste-buds which are located in
the squamous epithelium which lines its surface.

OUTLINE OF THE TONGUE.

Mucous coat.

f Squamous epithelium.

Membrana propria.

Papillae

Taste buds.
[ Furrows and ridges.

Fibres. . .

Filiform.

Fungiform.

Circumvallate.

f Branched.
1 Striated.

Muscular tissue

Adenoid tissue

Vertical.

•{ Bundles •{ Transverse.

Longitudinal.
Septum lingualae.

Interfascicular spaces f Connective tissue.

containing < Fat.

I Glands.
Reticulum.

Lymphoid cells.
Blood vessels, lymphatics, and nerves.

The tongue is constituted of a mucous coat, muscular tissue, ade-
noid tissue, blood-vessels, lymphatics, and nerves. The mucous coat
contains a superficial layer of stratified squamous epithelium. With-
in this layer are located the taste-buds, conical bodies which are the
seat of the sense of taste and are found upon the fungiform and
circumvallate papillae, and in the epithelium of the dorsum and sides
of the tongue. Beneath the squamous epithelial layer is the mem*

122 NORMAL HISTOLOGY.

brana propria. The elevations of the stroraa of the mucosa give rise
to the papillae. These are of three forms, filiform, or narrow ; fungi-
form, or club-shaped; and circumvallate, or broad and flat. The
circumvallate papilla are confined to the posterior part of the dor-
sum. The fungiform varieties occur upon the dorsum. Often sec-
ondary papilla? are present.

Glands occur in the stroma and are of the mucous and serous
types. The mucous glands are of the compound tubular variety,
and occur at the base and edges of the tongue. The serous glands
are of the saccular form, and occur near the circumvallate papillae
and taste-buds.

The muscular tissue of the tongue consists of striated muscle
fibres arranged in bundles which run vertically, transversally, and
longitudinally. The spaces between the bundles are filled up with
connective tissue, fat-cells, and glands. There is a connective tis-
sue partition, called the septum lingualce, which passes vertically
through the middle of the tongue, dividing the muscular tissue into
two portions.

The adenoid tissue at the base of the tongue is found in the
crypts, or depressions, of the mucosa, and consists of a connective
tissue reticulum and lymphoid ceils. The tongue is richly supplied
with blood-vessels, lymphatics, and nerves.

Laboratory exercise No. 38. — The tongue. Harden with alcohol, em-
bed in paraffin, and stain with carmine, method No. 3. Study first the
mucosa, demonstrating the epithelial layer, basement membrane, tunica
propria, and the filiform, fungiform, and circumvallate papillae. Make
a search for taste buds. Observe the loose fibrous structure of the
tunica propria and demonstrate, if possible, mucous and serous glands.
Notice the disposition of the bundles of striated fibres. Focus upon a
fibre with H. P. and demonstrate its striations. In the inter-fascicular
spaces observe connective tissue and fat-cells. A section prepared from
the base of the tongue should exhibit adenoid tissue in the crypts of the
mucosa. Does your section show the septum lingualae? Drawings.

II. THE TEETH.

The teeth are derived from the epiderm and mesoderm. The most
important structure of the tooth is the pericementum, or peridental
membrane, for upon its healthy action the condition and usefulness

TONGUE AND TEETH. 123

of the tooth depend. It serves to hold the tooth in place, as well as
to manufacture the cementum. The cavity which contains the tooth
and is lined by the pericernentum is called the alveolus. The layer
produced by the pericementum and covering the root of the tooth
is the cementum. The corresponding layer upon the crown of the
tooth is the enamel. The enamel and cementum enclose the den-
tine, commonly called ivory. In the cavity of the tooth, which is
surrounded by the dentine, is the pulp. The blood and nerve supply
of the tooth is conveyed through an opening at the extremity of each
root. A single nerve fibre enters each tooth and its branches follow
the course of the blood-vessels.

The enamel is derived from the epiderm ; the dentine and ce-
mentum. from the mesoderm. A tooth is developed from the dental
ridge, which forms the enamel organ, and from the dental papilla,
which consists of mesodermic connective tissue. The latter grows
up toward the enamel organ, so that the two are in contact. The
enamel organ produces the enamel, and the dental papilla produces
the dentine.

OUTLINE OF THE TEETH.

Alveolus.
Pericementum .

( Fibers.
| Fibroblasts.
1 Cementoblasts.
| Osteoblasts.
| Osteoclasts.
[Glands.

Dentine

f Fibrous reticulum.

Matrix ]

\ Calcareous salts.

Dentinal tubules.

fDentinal sheaths.

L Dentinal fibers.
Interglobular spaces.
Schreger's lines.
Lines of Salter.

C Membrane of Nasmyth.

Enamel < Enamel prisms.

[ Stripes of Retzius.

f Lamellae.

Cementum J Lacunae.

1 Canaliculi.
[ Corpuscles.

124 NORMAL HISTOLOGY.

f Connective tissue matrix.
-r, , I Stellate and spindle cells.

U1P 1 Odontoblasts.

[ Blood vessels and nerves.

Pericementum. — The structural elements of this membrane are
the fibres, the fibroblasts, the cementoblasts, the osteoblasts, osteo-
clasts, and glands. The -fibres are of the white fibrous variety, and
their chief function is to hold the tooth in position. The fibroblasts
are spindle-shaped cells which occur between the fibres. The osteo-
blasts are the bone formers, and are exactly like those of the peri-
osteum. The osteodasts are the giant cells which have the power
to dissolve calcareous matter. Cementoblasts engage in the forma-
tion of the cementum.

The cementum. — This covers the root of the tooth and differs
from bone in having no Haversian canals. It is thin at the neck,
but becomes thicker toward the extremity of the root. It is made
up of lamellae, lacunas, cement corpuscles, and canaliculi. The
canaliculi are supposed to communicate with the dentinal tubules.

Enamel. — The enamel exhibits the membrane of Nasmyth, the
enamel prisms, and the stripes of Eetzius. The membrane of Nas-
mytli is a tough epithelial sheath which covers the crown during its
earliest development. The enamel prisms are five or six-sided rods,
which extend out perpendicularly from the dentine. When enamel
is attacked by acids, it is completely dissolved, which is not true of
dentine and cementum.

Dentine.. — Some of the structures of dentine are the dentinal
tubules, interglobular spaces, lines of Salter, etc. The dentinal
tubules are minute canals, which extend from the pulp to the outer
surface of the dentine. Each tubule consists of a sheath called the
sheath of Neumann, within which is a dentinal fibril, a prolonga-
tion from an odontoblast of the pulp. The lines of Salter are lines
which appear in dried specimens, and are probably due to a shrink-
age of the tooth. The dentine is composed of twenty-eight per cent
of organic matter and seventy- two per cent of inorganic matter.
The interglobular spaces consist of uncalcified portions of the ma-
trix. They appear as irregular spaces and are sometimes quite abun-
dant.

TONGUE AND TEETH. 125

The pulp — This fills the cavity of the tooth within the dentine.
It consists of a connective tissue matrix, stellate and spindle cells,
round cells, and odontoblasts. The outer surface of the pulp is
covered with a layer of odontoblasts. Most of the cells beneath the
odontoblasts are stellate and spindle-shaped. The protoplasmic
processes of the odontoblasts, which extend into the dentinal tubules,
are called the fibres of Tomes. The odontoblasts are directly con-
cerned'in the manufacture of dentine.

Laboratory exercise No. 39.— The teeth. Decalcify in dilute nitric
acid, harden in alcohol, embed in celloidin, and stain with kaematoxylin.
Examine a longitudinal section and demonstrate as far as possible the
cementum with its lamellae, lacuna?, cement corpuscles, and canaliculi;
also the dentine, exhibiting dentinal tubules, sheath of Neumann, den-
tinal fibrils, and inter-globular spaces; also the enamel, showing the
enamel prisms, matrix, and membrane of Nasmyth. Drawings. The
demonstrations of enamel must be made from dry sections, as acids
completely dissolve this structure.

MEMORANDA.

TONGUE AND TEETH.

Tongue.

Tongue: (a) Mucous coat; (b) Squamous epithelium; (c) Taste buds; (d)
Membrana propria; (e) Filiform papilla; (f) Fungiform papilla; (g) Circumvallate
papilla; (h) Submucous tissue; (i) Muscular tissue; (j) Vertical fibers; (^Trans-
verse fibers; (1) Longitudinal fibers; (m) Septum lingualae; (n) Interfascicular
connective tissue; (o) Fat cells; (p) Adenoid tissue.

Teeth.

Teeth: (a) Pericementum— showing fibers, cementoblasts, etc.; (b) Cementum
—showing lamella, lacunae, canaliculi, and corpuscles; (c) Enamel — exhibiting
enamel prisms; (d) Dentine; (e) Dentinal tubule — showing dentinal sheath and
fibers; ( f ) Interglobular spaces; (g) Pulp; (h) Odontoblasts; (i) Stellate cells; (j)
Spindle cells.
[126]

NORMAL HISTOLOGY. 127

CHAPTEE XVIII.

THE RESPIRATORY SYSTEM.

The respiratory system includes the air passages of the nose,
mouth and pharynx, and the epiglottis, larynx, trachea, bronchi,
lungs, and pleura. Its structures are derived wholly from the epi-
derm and mesoderm. Its nerve supply is from the cerebro-spinal
and sympathetic systems.

Epiglottis. — This structure consists chiefly of yellow elastic car-
tilage. Its mucosa possesses many taste-buds and leucocytes.

Larynx. — The thyroid, cricoid, and arytenoid cartilages make up
the bulk of the larynx. These are united by fibrous tissue and liga-
mentous membranes and are covered internally with a mucosa, and
externally with fibrous tissue.

THE TRACHEA.

The trachea comprises a mucosa, a sub-mucosa, and fibrous coat.
It is largely a mesodermic structure.

OUTLINE OF THE TRACHEA.

f Ciliated epithelium.
1 M

Mucosa < Membrana propria. f Inner layer.

^ Tunica propria •{

[ Outer layer.
f Connective tissue.

Sub-mucosa 1 glood vessels? iymphatics, and nerves.

Smooth muscle.

f Perichondrium.

Hyaline cartilage < Matrix.

Fibrous coat <{ [ Cells.

Connective tissue.

The mucosa presents a superficial layer of stratified ciliated epi-
thelium supported by a basement membrane and a tunica propria
which possesses a large amount of elastic tissue and is disposed in
two layers : An inner layer of loose fibrous tissue containing elastic
fibres, nerve fibres, etc., and an outer layer, consisting of a dense
network of longitudinal elastic fibres. Of the epithelium, only the

128 NORMAL HISTOLOGY.

outer layer of cells possesses cilia. Among these occur the goblet
cells.

The sub-mucosa is made up of loose connective tissue containing
glands, blood-vessels, lymphatics, and nerves.

The fibrous coat invests the outer surface of the trachea and
has embedded in its tissue the incomplete rings of hyaline cartilage.
These rings in transverse section appear fusiform in outline, extend
over three-fourths, or less, of the circumference, overlap by their
edges, and exhibit pcrichondrium, matrix, lacunas, and cells. At-
tached to the perichondrlum upon the inner surfaces of the cartilage
are transverse bundles of smooth muscle, while across the intervals
between the rings are other bundles, the whole contrivance serving
to contract the tube. There are but few longitudinal muscular bun-
dles.

Laboratory exercise No. 40.— Trachea. Fix with ehromic acid, harden
with alcohol, embed in cello idin, and stain with hsematoxylin, method
No. 7. Make out the structures of the mucosa, observing especially the
layer of ciliated epithelium containing* a few goblet cells, the membraria
propria, and the two layers of the tunica propria. Search for glands,
blood-vessels, etc., in the sub-mucosa. Study the form and structure of
the hyaline cartilage in the fibrous layer. Note the disposition of the
bundles of smooth muscle. Demonstrate the loose areolar tissue which
unites the fibrous coat to adjacent structures. Drawings.

The bronchi. — These do not differ materially in structure from
the trachea. As the bronchial tubes decrease in size there are cer-
tain modifications in structure, such as: (1) The epithelium be-
comes reduced until in the smallest tubes there is but a single layer
of ciliated cells. (2) The elastic tissue disappears from the mu-
cosa and is replaced by a smooth muscle layer that corresponds to
the muscularis mucosae. (3) The cartilage gradually decreases and
totally disappears in the terminal bronchioles.

THE LUNGS.

The lungs are derived chiefly from the mesoderm. They resem-
ble in structure racemose glands. Their nerve supply is received
from the central and sympathetic systems.

THE RESPIRATORY SYSTEM.

129

OUTLINE OF THE LUNGS.

r Bronchial tubes.

Ducts •{ Bronchioles.

Alveolar ducts.

Spaces ^

' Infundibula.

. Alveoli.
r Lobes

i

Lobules <j

Infundib-
ular septa.
Alveolar

Pulmonary paren-
chyma . . . 4

i

Interlobular

walls.

Pleura

L Blood vessels, lymphatics, and nerves.

(" Endothelium.

<( Connective tissue.

[ Subpleural tissue.

The hings are invested with a connective tissue sheath, the pleura,
which is made up of endothelium, a connective tissue matrix, con-
sisting of fibrous tissue bundles and elastic fibres, and the sub-
pleural tissue, composed of areolar tissue and elastic fibres. Each
lung is comprised of lobes ; each lobe, of lobules ; and each lobule con-
sists of ducts, air spaces, and pulmonary parenchyma.

The smaller bronchial tubes, or bronchioles, become the terminal
bronchioles when their diameter does not exceed 1 mm. They end
in the alveolar ducts, which are lined with alveoli, or air sacs; and
extending from these ducts are irregular cavities, the infundibula,
which are also studded with alveoli.

The pulmonary parenchyma comprises the walls of blood-vessels,
lymphatics, bronchioles, and alveolar ducts, the alveolar walls, and
the infundibular septa. A bronchiole may be distinguished from
a blood-vessel under the microscope by the crenated appearance of
its inner surface. The terminal bronchioles are lined with a single
layer of ciliated epithelial cells, and their walls consist of elastic
fibres and smooth muscle. Each alveolar duct is lined with cu-
boidal cells, and its wall otherwise resembles that of a bronchiole,
but is much thinner. The wall of an alveolus is lined with simple
squamons epithelium and comprises also a connective tissue frame-
work and a dense capillary network. The connective tissue frame-

130 NORMAL HISTOLOGY.

work of elastic fibres surrounds each air sac and forms the septum
between adjoining alveoli.

Laboratory exercise No. 41.— Lungs. Fix in chromic acid, dehydrate
with alcohol, embed in celloidin, and stain with lithium carmine,
method No. 4. Make a careful study of the structures above named.
Demonstrate arteries, veins, and bronchioles. Distinguish between an
alveolus and an infundibulum. With H. P., make out the structure of
different portions of the pulmonary parenchyma. Drawings.

Trachea.

Trachea: (a) Mucous coat; (b) Ciliated epithelium; (c) Membrana propria; (d)
Tunica propria; (e) Submucous tissue ; (f) Hyaline cartilage— showing perichon-
drium, matrix, and cells; (g) Muscular coat; (h) Fibrous 'coat; (i) Serous coat.

Lungs.

Lungs: (a) Bronchiole; (b) Alveolar duct; (c) Alveolus; (d) Infundibulum; (e)
Infundibular septa; (f) Alveolar wall; (g) Artery; (h) Vein; (i) Pleura.

NORMAL HISTOLOGY.

131

CHAPTER XIX.

THE URINARY TRACT.

The organs of the urinary tract are the kidney, ureters, bladder,
and urethra. Their tissues are derived from the epiderm and meso-
derm. The nervous supply is obtained from the cerebro-spinal and
s}onpathetic systems.

THE KIDNEY.

The kidney is one of the parenchyinatous organs of the body, il-
lustrating a compound tubular gland and functioning as an organ
of excretion. The urine is secreted from the blood in the Mal-
pighian bodies and uriniferous tubules, and contains the products
of destructive metabolism.

OUTLINE OF THE KIDNEY.

Cortex

Medulla.

Sinus . .

Capsule.

Muscular
coat.

Malpighian i
bodv . . . . <

Labyrinth. . «

Column of
Bertini.

Medullary
rays.

Blood

vessels.

^ Urineriferous
tubule •

Stroma.

Malpighian
pyramids. <

' Base.

Tubules.

Hilum.
Pelvis.
Calices.

Papilla.

( Capsule of Bowman.
1 Glomerulus.

Neck.

Lumen.

Proximal convoluted tubule.

Spiral tubule.

Descending limb of Henle's

loop.

Henle's loop.
Ascending limb of Henle's

loop.

Irregular tubule.
Distal convoluted tubule.
Arched collecting tubule.
Straight collecting tubule.
Excretory duct, or tube of

Bellini.

The outside investment of the kidney is a capsule of fibrous tis-
sue, within which is a thin layer of smooth muscle. The cortex of

132 NOKMAL HISTOLOGY.

the kidney occupies the outer one-third and contains the labyrinth,
medullary rays, and blood-vessels. The labyrinth comprises the Mal-
pighian bodies and uriniferons tubules. The Malpighian body con-
sists of the capsule of Bowman and the glomerulus. The capsule
is lined with a single layer of flattened epithelial cells. The glom-
erulus consists of a coil of capillaries. Entering each capsule is an
afferent artery, and passing from it an efferent vein. The urinif-
erous tubule, which proceeds from the pole of the capsule opposite
the entrance of the artery, comprises the following parts : (1) The
neck, lined with low cuboidal cells; (2) the convoluted tubule,
which is lined with low columnar cells ; (3) the spiral tubule, similar
in structure to the convoluted portion; (4) the descending limb of
Henle's loop, lined with simple squamous epithelium; (5) Henle's
loop, composed of polyhedral cells with flattened nuclei; (6) the
ascending limb of Henle's loop, with structure resembling that of
the loop; (7) the irregular tubule, composed of striated epithe-
lium; (8) the distal convoluted tubule, consisting of granular
epithelium; (9) the arched collecting tubule, lined with low cu-
boidal cells; (10) the straight collecting tubule, which possesses
columnar cells; (11) the excretory duct, or tube of Bellini, which
is lined with tall columnar epithelial cells.

The columns of Bertini constitute the masses of the kidney be-
tween the Malpighian pyramids; they extend to the pelvis.

The medullary rays are tapering bundles of straight tubules,
which extend from the medulla into the cortex.

The blood-vessels of the kidney enter at the hilum. The renal
artery passes through the sinus, gives off twigs, which extend
through the columns of Bertini to the cortex, and enters the Mal-
pighian body by the afferent artery, which splits up into capillaries
to form the glomerulus ; these unite to form the efferent vein, which
unites with similar veins to form the interlobular vein.

The stroma constitutes the connective tissue structures, which in-
vest the blood-vessels and tubules.

The medulla is composed of from eight to twenty Malpighian pyr-
amids. Each pyramid is made up of tubules, its base corresponding
with the line of juncture between the medulla and cortex; and its

THE URINARY TRACT. 133

apex rests upon the sinus, and by its encroachment upon this .struc-
ture produces a papilla. The base of the pyramid is capped by the
cortical arch.

The sinus is the cavity at the basal portion of the kidney. The
opening into this cavity is the hilum. The cavity itself is formed
by a union of the excretory ducts, thus producing one large lumen,
and is invested with a coat which is continuous with the capsule
of the kidney, and within this is the wall, which is continuous with
that of the ureter. The space within this capsule is the pelvis.

THE URETER.

This structure is composed of three coats — mucous, muscular,
and fibrous. The mucous membrane is lined with the so-called tran-
sitional epithelium, which consists of few layers, the deeper layers
being columnar, and those next the lumen, squamous.

THE BLADDER.

The bladder has three coats — mucous, muscular, and fibrous. The
mucous coat is lined with stratified transitional epithelium, the cells
presenting considerable irregularity in shape, and often possesssing
more than one nucleus.

THE URETHRA.

The urethra consists of mucous and muscular coats. The mucous
coat of the female urethra is lined throughout with stratified squa-
mous epithelium. In the male urethra the prostatic portion is lined
with transitional epithelium, the intermediate part with stratified
columnar cells, while these are succeeded in the penile portion by
simple columnar cells.

Laboratory exercise No. 42. — The kidney. Harden with alcohol, em-
bed in paraffin, and stain with haematoxylin and eosin. Upon the onter
surface of your section observe the capsule, and beneath this a delicate
layer of smooth muscle. Distinguish between the cortex and medulla.
Observe the Malpighian pyramids of the medulla. Their apices form
the papillae, and their bases extend toward the periphery. What ele-
ments enter into their structure? The spherical, deeply-stained masses
in the medulla are the Malpighian bodies. Demonstrate the capsule of
Bowman and glomerulus; also the structure of a tubule, noting its
basement membrane, epithelial cells, and lumen. Make a study of
other structures enumerated in the outline of this organ. Drawings.

KIDNEY.

Cortex and Medulla.

Kidney: A. Cortex: (a) Capsule; (b) Muscular layer; (c) Labyrinth; (d) Malpighian body;
(e) Capsule of Bowman; (f) Glomerulus; (g) TJriniferous tubule; (h) Column of Bertini; (i)
Medullary ray; ( j ) Blood vessels; (k) Stroma.

B, Medulla: (1) Malpighian pyramid; (m) Base; (n) Apex, or papilla; (o) Tubules; (p)
Sinus — exhibiting hilum, pelvis, and calices,

Uriniferous Tubule.

TJriniferous Tubule: (a) Neck; (b) Lumen; (c) Proximal convoluted tubule; (d) Spiral
tubule; (e) Descending limb of Henle's loop; (f ) Henle's loop; (g) Ascending limb of Henle's
loop; (h) Irregular tubule; (i) Distal convoluted tubule; (j) Arched collecting tubule; (k)
Straight collecting tubule; (1) Excretory duct, or tube of Bellini.
[134]

NORMAL HISTOLOGY. 135

CHAPTEE XX
THE GENITAL ORGANS.

The reproductive organs are derived from the epiderm and meso-
derm. As among many plants, they exhibit sexual characteristics.
The function of the male organs is the production of semen, which
contains the spermatozoa, or male elements. The female organs
produce the ova, female elements, as well as contribute to the de-
velopment of the fertilized ova and the resulting embryos.

I. MALE REPRODUCTIVE ORGANS.

The male reproductive organs comprise the testis, prostate gland,
Cowper's glands, and penis.

THE TESTIS.

The testis is a compound tubular gland whose function is to pro-
duce the spermatazoa. It is enveloped in a fibrous capsule and is
divided into lobules.

OUTLINE OF THE TESTIS.

Tunica vaginalis.

Tunics •{ Tunica albuginea.

Tunica vasculosa.

Mediastinum, or corpus Hig-hmori.

Septa. C Parietal cells.

(Convoluted tubul^ ! Mother cells.

Tubili recti. ] Spermatoblasts.

Rete testis. [ Spermatozoa.

f Vasa efferentia.
j Coni vasculosi.
Vessels •{ Tube of epididymus.

Vas deferens.

Vas aberrans.

The testis is suspended in a sac, the scrotum, and is immediately
invested with three coats — the tunica vaginalis, or serous coat, de-
rived from the peritoneum; the tunica albuginea, or dense fibrous
coat, which on the posterior border of the testis forms by an inver-

136 NOKMAL HISTOLOGY.

sion of the capsule a much thickened mass, the mediastinum, or
corpus Highrnori; and the tunica vasculosa, containing a plexus of
blood-vessels invested by delicate areolar tissue. The septa, which
extend from the mediastinum to the tunica albuginea on the oppo-
site side, thus dividing the testis into lobules, are continuous with
tunica vasculosa. Each lobule is composed of tubules of three kinds
— convoluted tubules, tubuli recti, and those of the rete testis. The
convoluted tubule consists of a basement membrane lined with the
sustentacular cells, or parietal layer. Just within this layer are the
mother cells, which grow into large cells and multiply by mitosis.
Then follow the daughter cells, or spermatoblasts. Within these
are to be found the spermatozoa. These tubules are supported by
connective tissue derived from the septa, arc provided with blind
extremities, and each has a membrana propria. The tubuli recti
comprise the straight tubules formed by the union of the convoluted
tubules near the apex of the pyramidal lobule, and possess a base-
ment membrane lined with columnar cells. The rete testis consists
of anastomosing tubules forming a network within the mediastinum.

The vessels, or ducts, associated with the tubules are the vasa ef-
ferentia, coni vasculosi, epididymis, vas deferens, and vas aberrans.
The tubules of the rete testis emerge from the mediastinum in fif-
teen or twenty ducts, the vasa efferentia. These soon become con-
voluted in their course, forming conical masses, the coni vasculosi,
which together constitute the head of the epididymis, or globus
major. The tube of the epididymis is formed by the union of the
ducts of the coni vasculosi. This tube is greatly convoluted, and
when unraveled measures upward of twenty feet. The vas aber-
rans is a narrow tube, which extends from the lower part of the
tube of the epididymis and is closed by a blind extremity. The vas
deferens is continuous with the epididymis, and is the excretory duct
of the testis. It consists of three coats — epithelial, muscular, and
mucous.

THE PROSTATE GLAND.— This is composed largely of
smooth muscle, within which are a number of tubular glands, whose
ducts open into the urethra. The fibrous capsule is thin, but firm.

COWPER'S GLANDS. — These are two in number, and in

THE GENITAL ORGANS.

137

structure are of the compound tubular variety. The excretory duct
from each opens into the urethra.

THE PENIS. — The two corpora cavernosa and the corpus
spongiosum enter into the structure of this organ. The corpus
cavernosum consists of a fibrous sheath, trabeculae of connective tis-
sue, and smooth muscle. The corpus spongiosum resembles in struc-
ture the corpus cavernosum, but its connective tissue is more deli-
cate.

Laboratory exercise No. 43. — Testis. Harden in alcohol, embed in
paraffin, and stain with lithium carmine, method No. 3. Demonstrate
from your section the investing tunics (vaginalis, albuginea, and vascu-
losa), lobules, septa, interlobular connective tissue, parietal cells,
mother cells, spermatoblasts, and spermatozoa. Drawings.

II. FEMALE REPRODUCTIVE ORGANS.

The female reproductive organs are the ovary, parovarium, Fal-
lopian tubes, uterus, vagina, genitalia, and mammary glands

THE OVARY.

The ovaries correspond to the testes, are oval -shaped, and are
situated one on each side of the uterus. The following outline ex-
hibits their structure :

OUTLINE OF THE OVARY.

Cortex . .

Medulla. .

{ Tunica albuginea.

Strom a.

Graafian follicles. \

f Theca folliculi.
Membrana granulosa.
Discus proligerus.

Corpus luteum.
Stroma.
Blood vessels.

f Zona pellucida.

I Vitelline membrane.

t Ovum \ Vitellus.

I Germinal vesicle.
[ Germinal spot.

The tunica albuginea is a serous coat derived from the peri-
toneum. The cortex includes the outer one-third of the ovary ; and
the medulla, the inner two-thirds. The stroma is the connective tis-
sue ground substance. It contains numerous spindle-cells and occurs
in both medulla and cortex. The characteristic structures of the

138 NORMAL HISTOLOGY.

cortex are the Graafian follicles, each of which consists of the theca
folliculi, composed of an outer and inner coat; the membrana granu-
losa, comprising several layers of polyhedral cells; the discus pro-
ligerus, the zone of cells surrounding the ovum ; and the ovum, com-
prising the zona pellucida, an investing memhrane; vitelline mem-
brane, the cell-wall of the ovum; vitellus, the protoplasm of the ovum,
which occupies the space between the vitelline membrane and the
nucleus; germinal vesicle, which corresponds to the nucleus; and
the germinal spot, or nucleolus.

The number of Graafian follicles in the two ovaries of a child
is estimated to be 70,000. The liquid substance within the follicle
is the liquor folliculi. When the ovum is ripe it escapes by the
bursting of the wall of the follicle, which has gradually approached
the surface of the ovary. This makes it possible for the ovum to
reach the outside of the ovary, and pass thence to the Fallopian
tube. The ovum and Graafian f pllicle are developed from the germ
epithelium upon the surface of the ovary. As they develop, they
gradually pass into the deeper portion of the cortex. Upon the
escape of the ovum, the ruptured follicle becomes filled with poly-
hedral cells, which are penetrated by capillaries, and this stage is
the corpus luteum.

The medulla comprises the connective tissue stroma and blood-
vessels.

THE PAROVARIUMisof foetal origin, and is a remnant of
the Wolffian body.

THE FALLOPIAN tubes, or oviducts, convey the ova from
the ovary to the uterus. Each tube is composed of three coats — (1)
the mucous coat, comprising a single layer of ciliated epithelial cells,
a tunica propria of connective tissue, muscularis mucosa?, and a
small amount of sub-mucous tissue; (2) muscular coat, comprising
circular and longitudinal layers; (3) serous coat, derived from the
peritoneum, and composed of loose bundles of connective tissue.

THE UTERUS. — This is a continuation of the Fallopian tubes
and presents three coats — mucous, muscular, and serous. The mu-
cous coat consists of a fibrous tunica propria and a simple layer
of ciliated epithelium. Toward the cervical end, however, the mu-

THE GENITAL ORGANS. 139

cosa is thicker, is beset with papillae,, and its surface is lined with
stratified squamous epithelium. The muscular coat is dense and ia
disposed in three layers — inner, middle, and outer — with an inter-
mingling of blood-vessels, nerves, lymphatics, and areolar tissue.

THE VAGINA. — This structure possesses a mucosa, sub-mucosa.
and muscular and serous coats. The mucosa is studded with papil-
lae, and is lined with stratified squamous epithelium ; the sub-mucosa
consists of fibrous bundles and elastic fibres; the muscular coat is
in two layers; the serous coat comprises elastic fibres and endo-
thelium.

The mammary glands are sebaceous racemose glands, consisting
of lobes, lobules, and acini, with ducts, connective tissue, and areolar
and adipose tissues.

Laboratory exercise No. 44. — The ovary. Harden in alcohol, embed
in paraffin, and stain with haematoxylin and eosin. Demonstrate the
following-: Cortex, composed of tunica albuginea, stroma, Graafian folli-
cles, and corpus luteum; the medulla, consisting1 of the stroma and
blood-vessels. Make a study of a Graafian follicle, noting the theca
folliculi, membrana granulosa, discus proligerus, and ovum. Focus with
H. P. upon a ripe ovum and observe the vitelline membrane, vitellus,
germinal vesicle, and germinal spot. Drawings.

Laboratory exercise No. 45. — Fallopian tube and uterus. These may
be hardened in alcohol, embedded in paraffin, and stained with lithium
carmine, method No. 3. Make out (and illustrate in your diagrams) four
characteristic differences between these organs. How are the cilia dis-
posed?

MEMORANDA.

GENITAL ORGANS.

A. The Testis. B. The Ovary.

A. Testis: (a) Tunica albuginea; (b) Mediastinum; (c) Septa; (d) Lobules; (e) Convoluted
tubule; (f ) Parietal cells; (g) Mother cells; (h) Spermatoblasts; (i) Spermatozoa; (j) Basement
membrane; (k) Tubuli recti; (1) Rete testis.

B. Ovary: (a) Tunica albuginea; (b) Medulla, containing stroma and blood vessels: (c)
Cortex; (d) Stroma; (e) Graafian follicle; (f) Theca folliculi; (g) Membrana granulosa; (h)
Discus proligerus; (i) Ovum; (j) Corpus luteum,

Ovum: (a) Zona pellucida; (b) Vitelline membrane; (c) Vitellus; (d) Germinal vesicle; (e)
Germinal spot.

A. Fallopian Tube. B. Uterus.

A. Fallopian Tube: (a) Mucosa; (b) Ciliated epithelium; (c) Tunica propria; (d) Muscularis
mucosae; (e) Submucosa; (f ) Circular muscle layer; (g) Longitudinal muscle layer; (h) Serous
coat.

B. Uterus: (a) Ciliated or squamous epithelium; (b) Tunica propria; (c) Uterine glands; (d)
Folds; (e) Muscular coat; (f) Serous coat; (g) Endothelium.

[140]

NORMAL HISTOLOGY. 141

CHAPTEE XXI.
EYE, EAR, AND NOSE.

The organs of special sense are developed from the epiderm.
Their nervous supply is received from the cerebro-spinal system.
Only a brief discussion of the eye, ear, and nose is here given.

THE EYE.

There are three coats of the eye — an external fibrous tunic, a mid-
dle vascular tunic, and an inner nervous tunic.

1. The external coat includes the cornea and sclerotic mem-
brane.

The cornea is composed of five layers — (-1) The anterior epithe-
lium; (2) the anterior limiting membrane; (3) the substance
proper; (4) the posterior limiting membrane; (5) the posterior
endothelium.

The sclerotic membrane, or sclera, resembles the substantia pro-
pria of the cornea and consists of two structures — (1) bundles of
white fibrous tissue; (2) a layer of loose connective tissue, the lam-
ina supra choroidea.

2. The middle tunic comprises the choroid, ciliary body, and iris.
The choroid consists of three layers — (1) the choroidal stroma,

containing blood-vessels; (2) the capillary networks; (3) the vit-
reous membrane.

The ciliary body comprises three portions — (1) the ciliary ring;
(2) the ciliary processes; (3) the ciliary muscles.

The iris comprises the following structures : (1) The anterior en-
dothelium; (2) the anterior boundary layer; (3) the vascular layer;
(4) the posterior boundary layer; (5) the pigment layer.

3. The nervous tunic. — This tunic comprises the retina, which
consists of ten layers — (1) the pigment layer; (2) the layer of rods
and cones; (3) the external limiting membrane; (4) the outer nu-
clear layer; (5) the outer reticular layer; (6) the inner nuclear
layer; (7) the inner reticular layer; (8) the ganglion-cell layer;
(9) the nerve fibre layer; (10) the internal limiting membrane.

142 NORMAL HISTOLOGY.

THE EAR.

The specialized nemo-epithelium of the ear is found in the in-
ternal ear. It comprises two kinds of cells — the sustentacular cells
and the hair cells.

THE NOSE.

The neuro-epithelium of the nose consists of elongated cells with
spherical nuclei.

Laboratory exercise No. 46. — The eye. Fix in chromic acid, harden
in alcohol, and stain with carmine, method No. 3. Make a study of the
structures above enumerated, and as far as possible demonstrate the
layers of each coat. What is the character of the crystalline lens?
The vitreous humor is the same in character as the jelly of Wharton —
i. e., mucous tissue.

MEMORANDA.

PART III.

BACTERIOLOGY.

Bacteriology deals with minute vegetable organisms known as
bacteria, microbes, germs, etc. The science is comparatively new,
and while it is suggested in some quarters that it has accomplished
naught of practical value except the discovery of the bacillus of
consumption, thereby emphasizing the importance of properly dis-
posing of tubercular sputum, yet this alone is adequate compensa-
tion for the labor thus far bestowed. But this is not all. The work-
ers in this field have discovered the specific cause of a number of
other diseases, the means of preventing the spread of these diseases,
and certain remedies of inestimable value — such as the antitoxin for
diphtheria. The results of future investigations will probably ex-
ceed the hopes of the most sanguine.

CHAPTER XXII.
CHARACTERISTICS AND CLASSIFICATION OF BACTERIA.

Characteristics. — Bacteria are unicellular, non-nucleated, vegeta-
ble organisms, which reproduce by normal fission and by endospores.
With but three exceptions, they are devoid of chlorophyl. They are
parasitic and saprophytic. Many infest the human body, some
producing infectious diseases, while others are supposed to aid in
the processes of digestion and assimilation. They assist in the de-
composition of dead organic substances, thus performing an inesti-
mable service to man. They reproduce by normal fission and the
formation of endospores. Normal fission is accomplished by the
division of the protoplasm and the formation of a partition between
the two halves. As the cells continue to multiply, they often co-
here, thus forming a filament. In other cases the cells are held
together in masses, called zeoglcece. An endospore is formed some-

[143]

144

BACTERIOLOGY.

times in the middle of the rod, which becomes swollen centrally,
and the spindle-shaped ceil is called a dostridium. Often the spore
occurs in the end of the cell; again the whole cell may assume the
function of a spore, giving rise to the so-called arthrospore. Spores
are designed to perpetuate the species and to this end offer great re-
sistance to external influences, such as cold, heat, antiseptics, etc.
Dr. Curtis says : "Bacillus antliracis retains its vitality for some
time in absolute alcohol and withstands boiling in nutrient solutions
for an hour, and has germinated after three years7 confinement in
dry air/'

Classification of bacteria. — The present system of classification
is considered imperfect. The outline given below, while not com-
plete, will give a fair idea of the scheme, of classification considered
most satisfactory by good authorities :
Classification:

Kingdom — Vegetable.

Series — Cryptogamia.

Sub-kingdonx — Thallophyta.
Class — Fungi.

Sub-class — Schizomycetes.

Sub-class.

Group.

Family.

f Coccaceae

(spherical)

Schizomycetes, or
Bacteria . .

Monomor-
phous . .

Genus.

f Micrococcus.
Streptococcus.
Diplococcus.
Tetracoccus.
Staphylococcus.
Ascococcus.
Sarcina.

Pleomorphous

f Spirillum.
I Vibrio.

iBaeteriaeea.J %%$£*•
(rod-shaped) { p^teus

^ Bacterium.

SpirulineaB <J Spirulina.

( Leptothrix.

Leptotrichese. j CrfiSthrix.

[ Phragmidiothrix.

Cladotricheae . \ Cladothrix.

BACTERIOLOGY. 145

CHAPTER XXIII.

MORPHOLOGY, KINDS, AND PRODUCTS.
MORPHOLOGY.

The present classification of bacteria depends largely upon their
forms. When a species assumes but one form, it is said to be mono-
morphous; but if it possesses several forms, it is pleomorphous.

Monomorphous bacteria are represented by three important di-
visions : Cocci, spherical cells ; Bacilli, or rod-shaped bacteria ; and
Spirilla, or curved bacteria. Cocci are represented by several gen-
era — Micrococcus, in which the cells occur singly; Diplococcus, in
which the cells occur in pairs, the result of binary division; Tetra-
coccus, in which the cells occur as tetrads; Sarcina, in which the
cells occur in cubes, or packets ; Streptococcus, where Jhe cells occur
in chains, or filaments, the result of fission in one direction ; StapJiy-
lococcus, in which the cells occur in masses, like a cluster of grapes :
Ascococcus, in which the cocci are in globular masses.

Spirilla include the genera Spirillum, Vibrio, and Spirochoete.
The elements are curved, sometimes comma-shaped, and again in
long spirals.

Bacilli are represented by the genera Bacillus, Proteus, and Bac-
terium. The species of these genera are illustrated by rod-shaped
cells. The rods may be pointed at the ends, as in the clostridium ;
truncate, as with anthracis; round, as with subtilis. Some form
filaments, as anthracis; others are always single, as pyocyanus.
Some are slender, as tuberculosis; others, large and thick, as sub-
tilis. Involution forms occur where the rod deviates from the char-
acteristic form, due to external conditions or the death of the cell.

Pleomorphus bacteria are represented by Spirulina, Leptothrix,
and Cladothrix. Among these the individuals of each species as-
sume more than one form.

KINDS OF BACTERIA.

The following are the important kinds of bacteria :

1. Parasitic, those depending for subsistence upon a living host.
10

146 BACTERIOLOGY.

2. Saprophytic, those subsisting upon dead organic matter.

3. Aerobic, those requiring oxygen.

4. Anaerobic, those subsisting without oxygen.

5. Facultative, those that are anaerobic, but may become
aerobic; and those saprophytic that may become parasitic.

6. Pathogenic, those producing diseases in man and animals.

7. Chromogenic, those producing pigments.

8. Zymogenic, those producing fermentations.

9. Motile, those having independent motion.

10. Liquefying, those that produce a ferment which liquefies
solid nutrient gelatin.

PRODUCTS.

Bacteria are powerful agents in breaking up complex chemical
substances into simple ones. They attack the tissues of living
organisms and produce the toxins and ptomaines which cause the
symptoms of destructive diseases. They assist animals in destroy-
ing dead organic matter, else the earth would be covered with
its dead. Thus, by their cooperation with other humble or-
ganisms, they make life upon the earth possible. They assist in
manufacturing articles of economic value, such as butter, cheese,
etc. They convert starch into sugar, dissolve cellulose, change al-
bumin from an insoluble to a soluble form, convert urea into am-
monium carbonate, produce lactic acid in milk, produce acetic acid
from alcohol, and manufacture bright pigments.

The pigment formed by Badllis prodigiosus was once supposed
by the superstitious to be blood formed by supernatuTal power. Cer-
tain gaseous products are sometimes evolved by the action of bac-
teria. The foul odors from putrefying bodies may be ascribed to
their action. Among the common gases which are liberated from or-
ganic substances by the agency of bacteria may be named nitrogen,
carbon di-oxide, and sulphuretted hydrogen. The demonstration of
gaseous products may be made by the growth of certain species in
nutrient media in a saccharometer. Indol is produced by some spe-
cies. The test for this substance is made by adding to the peptone
solution in which the bacteria have been vegetating for twenty-four
hours about ten drops of c. p. sulphuric acid. The development of a

MORPHOLOGY, KINDS, AND PRODUCTS. 147

rose-color indicates the presence of indol and nitrites. Should no
rose-color appear, another tube should be tested, adding, first, 1 c. c.
of .01 per cent solution of sodium nitrite, and then the sulphuric
acid. The formation of a rose-color indicates the presence of indol
alone.

Laboratory exercise No. 47. — Morphology. Make cover-glass prepara-
tions of species of cocci, bacilli, and spirilla. Note the peculiar form
of the individuals of each species. To demonstrate the different kinds
of cocci, the following species may be used: Micrococcus urese, Diplo-
coccus pneumonias, Sarcina lutea, Streptococcus pyogenes, Staphylococ-
cus pyogenes aureus, and Ascococcus Billrothii.

Apply to the surface of a cover-glass some of the scrapings obtained
from the teeth just under the gums. Cover this with another glass and
by pressure spread out the material so as to make a thin film. Dry, fix,
and stain. (See method No. 10.) Examine your preparation and ob-
serve cocci, spirilla, and bacilli. Note the large ribbon-like forms,
which probably represent LeptotJirix buccalis. Make drawings to illus-
trate a]l of these forms.

Laboratory exercise No. 48. — Motility. Apply to a clean slide some
of the scum upon the surface of hay infusion. Cover and note the slen-
der filaments made up of rod-like cells. Each cell represents an indi-
vidual of Bacillus subtilis. Observe the slow, gliding motion of the fila-
ments. How is this motion secured? Look for other bacteria. Some
may be found with a vibratory motion. If this motion is confined to
one place without producing any progress across the field of vision, it
is purely physical, the so-called Brownian movement.

Laboratory exercise No. 49. — Products. Fill the long arm of the Sac-
charometer with bouillon and inoculate the medium with some zymogenic
species. The formation of gases in the upper end of the arm indicates
the action of the bacteria. Make the test for indol, as described above,
using as a culture-medium Dunham's Peptone solution, which is pre-
pared by boiling, filtering, and sterilizing a mixture of 10 grams of pep-
tone, 5 grams of sodium chloride, and 1 liter of water.

FORMS OF BACTERIA.

A. Cocci. B. Bacilli.

A. Cocci: (a) Micrococcus; (b) Diplococcus; (c) Tetracoccus; (d) Sarcina; (e) Streptococcus;
(f) Staphylococcus; (g) Ascococcus; (h) Zob'gloea.

B. Bacilli: (a) Single cells; (b) Filaments; (c) Cells with round, pointed, and truncate ex-
tremities; (d) Polar spore; (e) Glostridium with central spore.

C. Spirilla. D. Pleomorphous Forms.

C. Spirilla: (a) Spiral filament; (b) Comma-shaped cells.

D. Pleomorphous forms: (a) Spirulina; (b) Leptothrix; (c) Cladothrix.

[148]

BACTERIOLOGY. 149

CHAPTER XXIV.

SIZE, NUMBERS, AND DISTRIBUTION.

Size and numbers. — The unit of measurement for bacteria is
the micromillimeter, which is the thousandth part of a millimeter.
It is represented by the Greek letter /*. The size of Bacillus tuber-
culosis is: Length, 1.5/ji to 4,u; diameter, 0.2,u to 0.5, a. Some
cocci are as small as 0.1 5 /A in diameter; others as large as 2.8^i
in diameter. Bacilli range from lxO.2// to 5xl.5,u. Some spirilla
are40/jt long. The number of known species is upward of 1,000
The individuals of any species are countless. Dr. Sternberg states
that a milligram of the pure culture of StapJiylococcus pyogenes
aureus contains 8,000,000,000 individuals. The weight of an av-
erage bacterium has been estimated by Nageli to be 1-10,000,000,000
milligram.

The following estimates, as given by Williams, will give some
conception as to the number of bacteria that form a part of the in-
visible world of teeming organisms. The number of individuals in
1 c. c. of virgin soil is estimated to be upward of 100,000. Ordinary
milk contains more than 20,000 to 1 c. c. The number of bacteria
in a milligram of human fecal matter will range from 70,000 to
33,000,000.

Distribution. — The estimates just given will suggest that bacteria
are very widely distributed. Their spores float upon the dust of the
atmosphere in untold millions ; they swarm in the water we drink :
they teem in the soil to the depth of three feet ; they abound in food
and in all decaying substances; and they take up their abode in
the human body, being present in the alimentary tract in large
numbers, except in new-born infants. It is believed that the air
upon the high seas and upon mountain tops, the deeper layers of the
soil, the water of uncontaminated springs, and tfye tissues and fluids
of the normal body which are not exposed to the external atmos-
phere are free from their presence.

The presence of bacteria in soil, air, water, milk, blood, urine,
and fecal matter may be demonstrated by making plate cultures

150 BACTERIOLOGY

from the substances to be tested. If properly prepared the plate
will exhibit as many colonies, approximately, as there were indi-
viduals in the known amount of the material used. This furnishes
a working basis for counting the number of specimens in a given
quantity of any substance. By exposing a sterilized Petri dish con-
taining agar media to the air for a few moments and then cover-
ing, in a day or so many colonies will appear, indicating the kinds
and number of species which occur in the atmosphere. By plating,
these can be isolated, studied, and classified.

While in normal condition the human body is comparatively
free from bacteria, yet the alimentary and respiratory tracts always
contain large numbers, and, under abnormal conditions, the tissues,
blood, lymph, and urine often become infested. The products of
the mucous membrane (especially the hydrochloric acid) and the
serum of the blood, which are germicidal, as well as the phagocytes,
are generally effectual checks to the invading hosts.

The outer layers of the skin furnish the abode of many species,
and it is claimed to be impossible to dislodge all the germs that
occur under the nails.

There are certain agencies which influence the growth and dis-
tribution of bacteria. Electricity arrests growth. Sunlight will
kill Bacillus tuberculosis and other species, a few hours of sunlight
being sufficient to kill the vegetative cells of Bacillus anthracis.
Acids and oils are usually antiseptic. Some species require oxygen,
while others will not grow in its presence. Many species can with-
stand severe cold> but quickly succumb to a high temperature. The
temperature at which a species dies is called its thermal death
point. The thermal death point of a considerable number of spe-
cies is about 60 degrees Centigrade. There is a certain temperature
most favorable to the growth of each species. This for many spe-
cies is about 35 degrees Centigrade.

Laboratory exercise No. 5Q.^-Bacteria in air, water, soil, etc. Expose
to the air the agar-agar in a sterilized Petri dish for a few moments.
Examine in a day or so and observe and count the colonies upon the
surface of the medium. Note that they differ in form and color. In-
oculate five test-tubes of agur-ag-ar, one with each of the following sub-
stances: Soil, ordinary drinking* water, milk, urine, and saliva. These
materials should be collected in sterilized containers. Label each tube,
and in a few days examine for any growths which may have appeared.

BACTERIOLOGY. 151

CHAPTER XXV.

CULTIVATION AND SYSTEMATIC STUDY OF BACTERIA.
CULTIVATION OF BACTERIA.

This is accomplished by the use of certain media upon which the
species to be cultivated will grow. Such are potato, blood serum,
gelatin, and agar-agar. The medium, when prepared, is placed in
cotton-stoppered tubes and then sterilized. In the case of gelatin
and agar-agar, a steam sterilizer can be used, and sterilization
should be made on three successive days, from fifteen minutes to
one hour each day.

CULTURE MEDIA.

The following formulas for the preparation of culture media will
be useful:

1. Meat broth. — To one liter of water add one pound of finely-
chopped lean meat,, free from all fat. Let stand over night, or heat
for one hour, but do not boil. Filter.

2. Bouillon. — To one liter of meat broth add ten grams of pep-
tone and five grams of sodium chloride. The peptone and sodium
chloride should be thoroughly mixed in a mortar with water, until
a thin paste is formed, before adding them to the meat broth. Cook
one hour, filter, and alkalize with a solution of sodium carbonate.
Sterilize.

3. Agar-agar. — To one liter of bouillon add fifteen grams of agar.
Cook in sterilizer, or double sauce-pan, until agar is dissolved, one
to three hours. Neutralize with solution of c. p. Na2 Co3. Filter.
Cool to body temperature and add the whites of two eggs, which
have been previously mixed with 100 c. c. of water. Cook one hour.
Filter with coarse 'filter to remove coagulated albumen. Heat again
and filter with best filter paper previously moistened with boiling
water. Should any of the medium fail to filter through the first
paper, it should be heated again, and a second paper used for that
portion. Fill tubes and sterilize on three successive days. Cool
with tubes in oblique position.

152 BACTERIOLOGY.

4. Nutrient gelatin.— To one liter of bouillon add 100 grams of
finest gelatin. Heat twenty minutes in steam sterilizer. Alkalize
with solution of c. p. sodium carbonate and filter with filter paper
in steam sterilizer. Fill tubes. Sterilize for three successive days,
fifteen minutes each day.

5. Blood serum. — Collect blood in a sterilized container. When
coagulated, loosen clot and let stand twenty-four hours in a cool
place. Remove clear serum and fill sterile test-tubes with the same.
Coagulate at 65 degrees to 75 degrees Centigrade. Sterilize at 58
degrees Centigrade, one hour each day for six days.

6. Potato medium. — After thoroughly washing potatoes in soap
and water and removing eyes and spots, immerse in mercuric chlo-
ride solution, 1 to 1,000, for ten minutes. Make cylinders of the
potatoes the size of tubes; bisect obliquely, placing each half in a
tube. Sterilize for three successive days, a half hour each day.

As already suggested, each medium, when prepared, is to be
placed in cotton-plugged tubes, and then sterilized. The cotton
proves a perfect filter for the bacteria. Agar-agar may be kept for
months without any indication of growth of any kind, the cotton
plug preventing all access of germs from the outside.

INOCULATION.

The inoculation of the media is accomplished by means of a ster-
ilized platinum wire. A small portion of the pure culture of the
species desired is caught upon the loop at the end of the wire and
then drawn over the surface of the medium. Care should be taken
to sterilize the wire both before and after using.

PLATING.

A pure culture of a species is obtained by plating. This is ac-
complished by gently heating, until melted, the nutrient gelatin, or
agar-agar, in three tubes. With a sterilized platinum wire, a small
portion of the substance containing the bacteria is transferred to
the liquefied gelatin, or agar-agar, in tube number one. Then, after
sterilizing the wire again, a small quantity of the contents of tube
one is transferred to tube two. In like manner, tube three is inocu-
lated from tube two. Then the contents of the tubes are trans-

CULTIVATION AND SYSTEMATIC STUDY OF BACTERIA. 153

ferred to three sterilized Petri dishes. After numbering and label-
ing, the dishes are set aside for future examination. If colonies oc-
cur on plates two and three, they are probably pure cultures of the
species desired. From these colonies tubes containing media can
be inoculated.

HANGING-DROP CULTURES.

It is often very desirable to make a microscopic study of bacteria
and other organisms in the process of growth. This is accom-
plished by resorting to the hanging drop culture. A small drop of
the liquid media containing the species to be studied is transferred
by a platinum loop to the center of a sterilized cover-glass. This is
then inverted upon a slide in the center of which a concavity has
been ground out. The edges of the cover-glass are then sealed with
a layer of vaseline applied with a camelVhair brush. Th<3 prepara-
tion may then be studied from time to time, the focusing being ap-
plied to the edges of the preparation, rather than the center, which
will generally be found opaque.

INOCULATION OF ANIMALS.

To save human life it is of 1 en quite necessary to sacrifice the lives
of lower animals. The experiments of bacteriologists, while ap-
pearing to the superficial observer as almost merciless, are in the
interests of the highest humanity and are destined not only to di-
minish in a large degree the sum of human suffering, but to bring
alleviation to lower animals, at whose expense the requisite knowl-
edge is sought. The life of man outweighs that of a mouse or
" many sparrows.*' For purposes of experimentation, such animals
as mice, rats, guinea pigs, and rabbits are generally employed. In-
oculations are made in the ear, at the root of the tail, and elsewhere.
The hair is first removed by cutting or searing. A V-shaped inci-
sion is then made, and the infected material inserted by means of a
platinum wire. Inoculation of the blood may be made with a bac-
teriological syringe.

SYSTEMATIC STUDY OF BACTERIA.

The identification of any species can only be made after a thor-
ough study of its characteristics. Even then the determination will

154 BACTERIOLOGY

sometimes be attended with considerable difficulty and doubt. In
the systematic study of an unknown species, the following outline
may prove of service: (1) Name, (2) habitat, (3) growth on me-
dia, (4) temperature, including that of most favorable growth and
the thermal death point, (5) relation of growth to oxygen, (6)
gas formation, (7) chemical reaction, (8) formation of indol, (9)
pigmentation, (10) pathogenesis, (11) aniline reaction, (12) mo-
tility. (13) morphology, (14) size, (15) spore formation.

When these tests have been made, the classification may be de-
termined by using analytic keys, such as are found in the valuable
works of Sternberg and Crookshank.

Laboratory exercise No. 51. — Culture Media. Let the student prepare
or assist the instructor in preparing1 the following media: Bouillon,
agar-agar, blood serum, nutrient gelatin, and potato medium. Make
inoculations upon agar-agar as directed above. The tubes should be
held in the left hand, between the thumb and forefinger, in such a way
that the palm of the hand will be vertical and the tubes but slightly
inclined. The cotton plugs, when removed, may be held between the
fingers. The greatest care should be exercised, always sterilizing the
platinum needle before and after using. .Make a stab-culture of some
anaerobic species. This is accomplished by holding the tube in a ver-
tical position, using a platinum wire with small loop, and plunging this
through the center of the medium from the surface to the bottom of the
tube.

Experiments with animals. Clip the hair from the base of the tail of
a mouse. Make a V-shaped incision and insert into the wound some of
the saliva of the mouth. Saliva often contains Diplococcus pneumoniae,
which will cause the death of an inoculated mouse in a few hours.
Other inoculations may be made as desired.

Laboratory exercise No. 52. — Hanging-drop Cultures. Prepire a hang-
ing-drop culture upon which have been sown some spores of any species
of mold, such as Penicillium glaucum. After a few days examine. The
spores of molds may sometimes be mistaken for cocci. The hyphae,
or slender filaments, which compose their structure, may, when broken
into fragments, have some resemblance to the cells of bacilli. The
hyphae develop from the spores, producing three characteristic por-
tions— the root hyphas; the mycelium, or prostrate portion; and the
aerial hyphae, upon the extremities of which the sporangia containing
the spores are developed. Also make hanging drop cultures of species
of bacteria, and study the same from time to time.

Laboratory exercise No. 53. — A systematic study of Bacteria. Make a
systematic study of Bacillus prodigiosus and other common species ac-
cording to the method suggested above. Fill out the outline on page 155
and make drawings of agar cultures and the microscopic elements.

OUTLINE FOR SYSTEMATIC STUDY.

Species ,

1. Habitat

2. Growth on media —

(1) Gelatin

(2) Agar-agar

(3) Blood-serum

(4) Potato

3. Relation to temperature —

(1) Best growth

(2) Thermal death-point

4. Relation to oxygen

5. Gas formation

6. Chemical reaction

7. Formation of indol 4

8. Pigmentation

9. Pathogenesis

10. Anilin reaction (Gram's method) .

11. Motility

12. Morphology

13. Size

14. Spore formation

15. Classification . .

[155]

156 BACTERIOLOGY.

CHAPTER XXVI.

MICROSCOPIC TECHNIQUE.

I. REAGENTS AND STAINS.

(1) DECOLORIZING SOLUTIONS.

Twenty-five per cent aqueous solutions of hydrochloric, nitric,
and sulphuric acids may be used for decolorizing.

(2) ACID ALCOHOL.

Hydrochloric acid 1 part

Alcohol (seventy per cent) 100 parts

(3) IODINE SOLUTION.

Iodine 1 gram

Potassium iodide 2 grams

Water 300 cc.

(4) CARBOL FUCHSIN.

Fuchsin 1 cc.

Alcohol 10 cc.

Dissolve and add 10 c. c. of five per cent solution of carbolic acid.
Filter.

(5) ACID METHYLENE BLUE.

Sulphuric acid 16 cc.

Water 90 cc.

Methylene blue 2 grams

This stain should be prepared fresh from time to time. The
carbol fuchsin improves with age.

(6) LOFFLER'S ALKALINE METHYLENE BLUE.

Concentrated alcoholic solution of methy-

lene blue 30 c.

Potassum hydrate (Aq. Sol., 1-10,000) 100 cc.

This is especially useful in staining the baccillus of diphtheria.

(7) ANILINE-WATER GENTIAN-VIOLET.

Aniline oil 5 cc.

Water.. ..100 cc.

MICROSCOPIC TECHNIQUE. 157

Mix, shake vigorously, filter; the fluid after filtration should be
perfectly clear; add

Alcohol 10 cc.

Alcoholic solution of gentian-violet 11 cc.

This solution should be freshly prepared about every two weeks.

(8) LOFFLER'S MORDANT FOR FLAGELLA.

Tannic acid 2 grams

Water 8 cc.

Saturated solution of ferrous sulphate 5 cc.

Saturated alcoholic solution of fuchsin 1 cc.

(9) ANILINE-WATER DYE FOR STAINING SPORES.

Saturated alcoholic solution of fuchsin or

gentian-violet <• 11 parts

Aniline oil water 100 parts

Abs. alcohol 10 parts

Keeps well for ten days.

(10) AQUEOUS STAINS.

Saturated aqueous solutions of fuchsin, gentian- violet, and
methyline blue will be found useful for all simple staining.

(11) ALCOHOLIC SOLUTIONS.

Saturated alcoholic solutions of fuchsin, gentian-violet, and
methyline blue should be kept on hand to be used in simple staining
and in connection with other stains.

II. STAINING METHODS,

(1) SIMPLE STAINING.

This consists in using a single stain. The process is given on
page 27, method No. 10.

(2) DOUBLE STAINING.

This consists in using two stains, one to stain spores, protoplasm,
etc., and the other as a ground stain. The following methods will
illustrate double staining:

158 BACTERIOLOGY.

Method No. XII. — Staining of Spores.

(a) Make a cover-glass spread, dry and pass three times through the
flame.

(b) Add aniline-water gentian-violet.

(c) Heat until the preparation begins to boil; remove for a minute.
Repeat this process six times.

(d) Wash in three per cent hydrochloric acid-alcohol one minute

(e) Wash in water.

(f) Counter-stain with aqueous methylene blue half a minute.

(g) Wash in water.

(h) Dry and clear up with xylol.
(i) Mount in balsam.

Method No. XIII.— Staining of Flagella.

(a) Mix upon the cover-glass a portion of the culture with a drop of
water, using care not to break off the delicate flagella.

(b) Dry and pass three times through a flame.

(c) Apply Loffler's mordant one minute, warming gently.

(d) Wash in water.

(e) Stain with aniline-water fuchsin.

(f) Wash in water.

(g) Dry and mount in balsam.

Method No. XIV.— Grain's Method for Bacteria.

(a) Make a cover-glass preparation by the usual method.

(b) Stain with aniline-water gentian-violet solution, two to five min-
utes, warming slightly.

(c) Add Gram's iodine solution one and one-half minutes.

(d) Apply alcohol, repeatedly, as long as stain continues to come
away from the preparation.

(e) Wash in water and examine as a water-mount.

(f ) If desired, dry and mount in balsam.

Method No. XV. — Gabbet's Method for Tuberculosis, etc.

(a) Make a cover-glass smear of the sputum, pus, blood, or urine to
be examined. After the preparation is dry, affix by passing three times
through the flame.

(b) Using a Cornet forceps, apply carbol-fuchsin five to ten minutes,
heating until steam appears.

(c) Wash in water.

(d) Apply alkaline methylene blue for one minute.

(e) Wash in water.

(f) Dry and mount in balsam.

MICROSCOPIC TECHNIQUE. 159

Staining Tissues for Bacteria.

Tissues may be stained by Gram's method or by the following
process :

Method No, XVI. — Method for Staining Bacteria in Sections,

(a) Using an aqueous solution of fuchsin, gentian-violet or methy-
lene blue, apply stain for about five minutes.

(b) Wash in water.

(c) Apply an aqueous solution of acetic acid, one per cent, for one
minute.

(d) Apply alcohol one to two minutes.

(e) Clear up with xylol.

(f ) Mount with balsam.

MEMORANDA.

160 BACTERIOLOGY.

CHAPTER XXVII.
NON-PATHOGENIC BACTERIA.

Material for the practical study of non-pathogenic species may
be obtained from air, water, soil, and other sources. The biological
characteristics of a few of the more common species are here given
to assist the student in experimental work.

I. Bacillus Prodigiosus.

This species is a chromogcnic, non-motile, facultative anaerobic
saprophyte. It produces a pigment-forming body, which becomes
red by the action of oxygen. The pigment gives rise to the " red
mould " of bread. The rods are short, often in filaments, without
spores. It grows rapidly upon agar-agar, or potato, at the room
temperature, and soon liquefies nutrient gelatin. It grows best at
25 degrees Centigrade. It may be obtained from the air.

II. Bacillus Acidi Lactici.

Bacillus acidi lactici occurs in sour milk, producing lactic acid.
It is a non-motile, facultative anaerobic saprophyte. It produces a
whitish growth on agar-agar, does not liquefy gelatin, ancl the rods
occur in pairs or short filaments, producing large shining polar-
spores. It causes milk to sour, changing its sugar into lactic acid
and CO 2, and precipitates casein. It will grow at 10 degrees Cen-
tigrade; but, when cultivated for several generations, it loses its
power to produce fermentation..

III. Bacillis Subtilis.

This species may be obtained from hay infusions, air, water, soil,
etc. It produces a grayish growth on agar, and liquefies gelatin. It
is a motile aerobic saprophyte, and grows rapidly at ordinary tem-
peratures. The rods are thick and stout, with rounded extrem-
ities, and provided with flagella. It produces motile spores.

IV. Bacillus Violaceus.

This bacillus is found in water. It is aerobic, motile, and chromo-
genic; grows at room temperature, and on agar produces a violet-

NON-PATHOGENIC BACTERIA. 161

colored covering which lasts for years. The rods are slender, with
rounded ends, and produce small oval spores. It grows upon agar
and liquefies gelatin.

V. Proteus Vulgaris.

Proteus vulgaris is found in putrefying animal matter; is a facul-
tative anaerobic motile saprophyte; has rods with rounded ends,
which grew into flexible filaments; produces a whitish growth on
agar, and liquefies gelatin; forms H2 S, and causes putrefaction, oc-
casionally being pathogenic to man.

VI. Micrococcus Urese.

This species may be obtained from cystitic and decomposing urine.
The cocci occur singly, in pairs, or in filaments. It is an aerobic
saprophyte, grows readily at room temperature, and does not liquefy
gelatin. Plate cultures appear like a drop of wax upon the sur-
face.

VII. Sarcina Lutea.

Sarcina lutea may be obtained from the air. It is an aerobic
chromogenic species, whose cocci occur in 'pairs, tetrads, and pack-
ets. The pigment is yellow. It liquefies gelatin slowly.

VIII. Spirillum Rubrum.

This is a motile chromogenic facultative anaerobic species. It
may be found in the putrefying cadaver of a mouse. The spirals
make three-quarter turns. It groAvs on agar, stab cultures, form-
ing a red pigment.

Laboratory exercise No. 54. — Bacillus subtilis. Prepare a pure cul-
ture of this species and inoculate tubes of agar and gelatin. Make a
study of the growths upon these media, describing- each. Make a water-
mount and demonstrate the motility of the rods and filaments. Make a
cover-glass preparation and stain with gentian-violet, method No. 10.
Demonstrate flagella, staining by method No. 13. Demonstrate spores
by method No. 12. Prepare an outline of this species as indicated on
page 155. Make drawings of cultures and rods.

Laboratory exercise No. 55. — Micrococcus ureae. Obtain plate cultures
from decomposing urine. Note the wax-like colonies. Make a cover-
glass preparation and stain with gentian-violet. Observe the spherical
cells arranged singly, in pairs, and in chains. How does this species
11

162 BACTERIOLOGY.

affect urea? Prepare an outline, as with the last species, and make
drawings of cultures and cells.

Laboratory exercise No. 5Q.—8arcina luted. Expose agar-agar in a
Petri dish to the air, and from the j^ellowish colonies which develop
prepare plates. Inoculate tubes (from the pure cultures thus obtained)
of agar and gelatin. Describe the growth in each tube. Stain by
method No. 10. Note the cocci, arranged singly, in pairs, in tetrads,
and in packets. Make drawings of cultures and cells.

Laboratory exercise No. 57. — Spirillum rubrum. Obtain a pure culture
of this species. Prepare a cover-glass spread, and stain with gentian-
violet, method No. 10. Note the spirals and count the turns in each.
Drawings.

Note. — Other species may be substituted for those given above, and
additional ones may be required.

MEMORANDA.

NON-PATHOGENIC BACTERIA.

A. Bacillus Subtilis. B. Micro-coccus Ureee.

A. Bacillus subtilis: (a) Culture tube; (b) Cells.

B. Micrococcus urese; (a) Culture tube; (b) cells.

A. Sarcina Lutea. B. Spirillum Bubrum.

A. Sarcina lutea: (a) Culture tube; (b) Cells.

B. Spirillum rubrum: (a) Culture tube; (b) Cells.

[163]

1 64: BACTERIOLOGY.

CHAPTER XXVIII.
PATHOGENIC BACTERIA.

In all practical work with pathogenic bacteria, more than ordi-
nary care should be used. While the danger attending such work
should not be unduly magnified, the student will do well to attend
carefully to any abrasions on the skin; he should be scrupulously
neat and cleanly, not allowing the material used to be carelessly scat-
tered; he should dispose of all material as soon as used, and care-
fully cleanse the hands at the close of each period. It is doubt-
less true that Bacillus mallei has caused the death of more bac-
teriologists from accidental infection than all other species to-
gether. The diseases known to be produced in man by bacteria are
tuberculosis, leprosy, glanders, anthrax, tetanus, erysipelas, gonor-
rhoea, pneumonia, influenza, diphtheria, typhoid fever, Asiatic chol-
era, relapsing fever, malignant edema, bubonic plague, and sup-
puration. It is believed that some kind of micro-parasite will be
found to be the specific cause of each of the following diseases — viz.,
syphilis, mumps, smallpox, chicken pox, measles, scarlet fever, yel-
low fever, whooping cough, and others. The limited space of this
Manual will allow but a brief discussion of a few of the more im-
portant species.

I. Bacillus Tuberculosis.

This species is the recognized cause of consumption, or tubercu-
losis. It is a non-motile facultative saprophyte, and consists of
slender, beaded staves. It may be cultivated on glycerine agar-agar,
growing best at 37 degrees Centigrade. It -reproduces by fission,
and probably by spore-formation. It is also pathogenic to a num-
ber of animals. Man may become infected through wounds, through
nutrition — such as the milk of tuberculous cows — and by inhala-
tion. The sputum of the consumptive, if not properly destroyed,
dries and becomes pulverized. As dust, it floats in the atmosphere,
is inhaled, and under suitable conditions produces infection. It is
doubtful whether any one is immune from the disease.

PATHOGENIC BACTERIA. 165

Tuberculin is prepared by concentrating with heat the glycerine-
bouillon, containing an old growth of tuberculosis, and filtering
through unglazed porcelain. It is used for the detection of tuber-
culosis in animals. The suspected animal is injected with the
tuberculin,, and a sudden rise of temperature, or suppuration of
tubercular formations, may be considered as proof that the ani-
mal is infected with the disease.

II. Bacillus Typhosus.

The bacillus of typhoid fever is a motile parasite found in the
urine and fecal discharges of typhoid patients. The rods have
rounded ends, and sometimes grow out into long filaments. It pro-
duces a whitish growth on agar, growing best at 35 degrees Centi-
grade. Spore-formation has not been observed. It may be stained
with aqueous solutions of fuchsin, methylene blue and gentian-
violet.

The detection of typhoid in a patient may be made by adding to
some serum obtained from his blood a 'quantity of pure culture. It
the patient has the disease, the motile germs will soon cease their
movements. Flagella may be demonstrated by method No. 13.

III. Bacillus Pyocyanus.

This species is an actively-motile aerobic parasite, presenting
very short, slender staves. It is found in green pus, and produces a
greenish- white growth on agar-agar at the room temperature. It
may be stained with aqueous fuchsin.

IV. Bacillus Anthracis.

This bacillus is the specific cause of anthrax in cattle and the
so-called " wool-sorter's disease " in men. It occurs in rods, which
have truncate ends (slightly indented), and generally grow out
into long filaments. It produces a dry, easily-detached growth on
agar, and readily liquefies gelatin. Its movements are rotary. The
spores are ovoid, may be central or polar, and are very resisting,
having been known to live twenty years. It stains well with aque-
ous fuchsin or gentian- violet.

166 BACTERIOLOGY.

V. Bacillus Diphtherise.

This is found in diphtheretic membrane. It is a non-motile, aero-
bic species. On agar it produces a yellowish- white growth, with cre-
nated edges. The rods are straight, or curved, and, when stained,
often present the appearance of a dumb-bell, owing to the deeper
staining of the polar protoplasm. It grows best at 35 degrees Cen-
tigrade, and stains well with Loffler's methylene blue.

The antitoxin of diphtheria is produced by inoculating a horse
with a small amount of diphtheria toxin and following this up with
an increased dose every six days, until upwards of 1,000 c.c. can
be introduced at a time. As a result of this, the serum of the blood
becomes immune to the influence of the toxin. A portion of the
blood is then removed from the jugular vein of the horse, and, after
coagulation, the serum is tested, bottled, and sold in so-called units
of strength. A unit of antitoxin has been tersely denned by Mac-
Farland as "ten times the least amount of antitoxic serum that
will protect a standard (300-gram) guinea pig against ten times the
least certainly fatal dose of diphtheria toxin." A child of the writer
was supposed to have diphtheria, bacteriological tests made imme-
diately proving the suspicion to be well founded. Within twenty-
four hours of the first appearance of the diphtheretic membrane,
100 units of antitoxin were administered, and in three days the child
was considered well.

VI.. Staphylococcus Pyogenes Aureus.

This species occurs in suppurations. The cells are spherical in
form and occur singly, or in clusters resembling bunches of grapes,
called zooglcese. It is a non-motile anaerobic facultative parasite.
It produces a yellowish growth on agar, grows at the room tem-
perature, liquefies gelatin, and stains well with aqueous solutions.

VII. Streptococcus Pyogenes.

Streptococcus pyogenes is found in erysipeloid suppurations. The
cells are spherical, and occur in pairs and chains. It is a non-mo-
tile facultative anaerobe, growing best at 35 degrees Centigrade,
producing a grayish- white line on agar-agar. It stains well with
aqueous fuchsin, or gentian-violet.

PATHOGENIC BACTERIA. 167

VIII. Diplococcus Pneumoniae.

This is found in normal saliva and in the sputum of croupous
pneumonia. The cells are lance-shaped, occurring in pairs, sur-
rounded by a capsule. It is a non-motile facultative saprophyte, and
produces round, grayish- white colonies on nutrient gelatin, and is
non-liquefying. It may be stained by Gram's method or with the
aqueous solutions of aniline dyes. Injected into a mouse, it pro-
duces spetic93mia.

IX. Bacillus Coli Commune.

The colon bacillus is found associated with typhosus in typhoid
fever, and with Micrococcus urcw in cystitis. It is recognized as
the cause of most of the summer complaints among children, and is
almost invariably found in the feces of healthy persons. It is mo-
tile, grows luxuriantly on ordinary media; produces acids, gases,
and indol; coagulates milk, and does not react with typhoid blood.
It may be stained with fuchsin or gentian- violet.

X. Micrococcus Gonorrhoeae,

This microbe is the cause of gonorrhoea. It occurs in gonorrhceal
discharges from the urethra, the somewhat hemispherical cells oc-
curring on the surfaces of epithelial cells, or in pus-cells in pairs
or tetrads. It is a non-motile facultative anaerobe. The cocci do
not stain by Gram's method, but may be stained with Loffler's
methylene blue or aqueous solutions of fuchsin and gentian-violet.
It does not grow upon gelatin.

Other species which may be studied are the Bacillus tetani of
tetanus, Bacillus influenza of influenza, Baccillus leprce of leprosy,
Bacillus mallei of glanders, Spirillum cholerce of cholera.

Laboratory exercise No. 58. — StapJiylococcus pyogenes aureus. Make a
systematic study of this species and write out a full outline according*
to the form given on page 155. Stain by method No. 10. and study with
one-twelfth oil-immersion objective. Make out single cells and a zo-
oglcea.

Laboratory exercise No. 59. — Streptococcus pyogenes. Make a sys-
tematic study of this species, preparing an outline and making the
required drawings. Stain with aqueous or carbol fuchsin. Observe
single cells and slender bead-like filaments.

168 BACTERIOLOGY.

Laboratory exercise No. 60. — Micrococcus gonorrhaxv. Make a cover-
glass preparation from gonorrhceal discharges and stain with Loffler's
methylene bine or carbol fuchsin, method No. 10. The hemispherical
cocci will be found in pairs or tetrads on epithelial cells or within pus
cells.

Laboratory exercise No. 61. — Bacillus tuberculosis. Make a rather
thick smear of tubercular sputum upon a cover-glass, dry thoroughly,
and stain by method No. 15. Observe the slender, beaded, somewhat
curved rods. Find two attached by their extremities forming a V-shape.
Account for the beaded appearance.

Laboratory exercise No. 62. — Bacillus typhosus. Make a systematic
study of this species and prepare an outline of your work. Observe the
motility of vegetative specimens. Demonstrate flagella, method No. 13.
Make a permanent preparation, staining with gentian-violet. Look for
small oval spaces in the ends of some of the degenerated bacilli.

Laboratory exercise No. 63. — Bacillus anthracis. Make, a systematic
study of this species and prepare an outline. Stain a permanent prepa-
ration with gentian-violet. Make a study of the long filaments. Dem-
onstrate spores by method No. 12. Harden, embed, and section the
heart and lungs of a mouse that has been killed by Bacillus anthracis,
and stain by method No. 16. Search for bacteria.

Laboratory exercise No. 64. — Bacillus coli commune. Make a sys-
tematic study of the colon bacillus. State all the points of difference
between this species and Bacillus typhosus. Stain your permanent
preparation with fuchsin or gentian-violet. Make drawings of all spe-
cies studied.

Laboratory exercise No. 65. — Bacillus diphtheriae. Make a study of
cultures of the diphtheria bacillus on different media. Describe the
process of making a bacteriological diagnosis of diphtheria. Stain a
cover-glass preparation with Loffler's methylene blue and make a study
of the cells. Observe the dumb-bell forms. A good lens will always
exhibit complete rods, showing that the protoplasm of the polar ends
is connected. Search for involution forms, also for three or four cells
joined by their extremities, noting that no chains are formed. Draw-
ing.

PATHOGENIC BACTERIA.

Diagrams Showing Cells, Spores, etc.

A. Staphylococcus pyogenes aureus; B. Streptococcus pyogenes; C. Micrococcus gonorrhoeas;
D. Bacillus tuberculosis.

Diagrams Showing Cells, Spores, etc.

.

A. Bacillus typhosus; B. Bacillus anthracis; G. Bacillus coli commune; D. Bacillus cliph-
theriae.

1713 BACTERIOLOGY.

CHAPTEE XXIX.

IMMUNITY, TOXINS, ETC.— GERMICIDES, ANTISEPTICS, ETC.

Ptomaines. — This term applies to all compounds of a basic na-
ture produced by the agency of bacteria, They act upon the sys-
tem to produce the symptoms of the diseases ascribed to the species
through whose agency they are manufactured.

Toxalbumins. — These are proteid poisons produced by bacteria,
and they give rise to the symptoms of the larger number of infec-
tious diseases.

Leucomaines have been defined as " basic substances which re-
sult from tissue metabolism in the body/'

Toxins, — This is a general term applied to all poisons produced
by bacteria, and especially to those of unknown composition.

Antitoxins. — Bacteria also produce another class of compounds
known as antitoxins. These act upon the tissues in such a way
as to prevent bacterial infection.

Immunity. — This term is applied to the power of resistance to
bacterial infection which may be exerted by an individual man or
animal. This may be natural ; or it may be acquired by disease, ac-
climatization, vaccination, the injection of antitoxins, and other
means.

An antiseptic is a substance which simply retards the growth of
bacteria.

A germicide is a substance which will kill bacteria, The term
" disinfectant" has the same significance. Among the commonly used
and most effective germicides may be named the following: Car-
bolic acid, mercuric chloride, silver nitrate, formaldehyde, sulphur
dioxid, calcium hypochlorite, lime, potassium permanganate, and
copper sulphate.

For the destruction of the sputum of consumptives and the
evacuations of cholera and typhoid patients, Crookshank recom-
mends the use of carbolic acid, one in twenty, or a strong solution
of chloride of lime. Disinfection of the skin is often difficult, as a
number of species are of frequent occurrence upon its surface, such

IMMUNITY, TOXINS, ETC. 171

as Streptococcus pyogenes, Staphylococcus pyogenes aureus (also
albus and citrous), Bacillus tuberculosis, Bacillus pyocyanus, and
others. Staphylococcus epidermidis albus finds its normal habitat
in the skin. Under ordinary circumstances, sponging the skin with
carbolic acid, one in forty, or rinsing it in bichloride of mercury,
1 in 1,000, will give satisfactory results.

For the disinfection of wounds, hydrogen peroxide is recom-
mended. As a wash for the mouth and throat in cases of inflamma-
tion, abrasion, and suppuration, a weak solution of permanganate
of potash will be found very efficient when used as a gargle.

Fetri Dish.

Bausch & Lomb Optical Co.

MEMORANDA.

F=» A. « T I V.

URINALYSIS.

The clinical significance of urinalysis renders this subject of
paramount importance to the physician. Only a bare outline is
here given of some of the important processes of physical and chem-
ical urinalysis. ' In the preparation of this outline Purdy's " Prac-
tical Urinalysis and Urinary Diagnosis " has been consulted. Those
who may contemplate pursuing these investigations more exhaust-
ively will not be disappointed if they secure this admirable text.
The microscopical examination of urine is valuable in demonstrat-
ing pus, bacteria, animal parasites, blood, fat, epithelium, inorganic
crystals, and other products, thus affording very valuable assistance
in the detection of abnormal conditions. The few practical exer-
cises pointed out in this brief discussion are only suggestive of the
field which might be explored by the ambitious student.

CHAPTER XXX.

PHYSICAL, CHEMICAL, AND MICROSCOPICAL URINALYSIS.
1. PHYSICAL URINALYSIS.

The physical examination of urine includes the following deter-
minations :

1. The amount voided in twenty-four hours. — This determina-
tion is important as a basis upon which to estimate the quantity of
solid matter eliminated in a given period. It also indicates the
possible presence or absence of such diseases as uraemia, diabetes,
and Bright's disease. The normal quantity passed, in twenty-four
hours ranges from 1,000 c.c. to 2,000 c.c., the average in a healthy
person being 1,500 c.c.

2. Odor. — The odor may be aromatic, ammoniacaL, putrid, or
scarcely perceptible. The odor of freshly-voided normal urine is

[172]

PHYSICAL URINALYSIS. 173

slightly aromatic. A putrid odor indicates tissue degeneration or
the decomposition of the urine within the body.

3. Color. — The color of normal urine ranges from that of water,
through the yellows, to reddish brown, the average being straw,, or
amber, color. The color is due to certain pigments. Concentrated
urine is more highly colored than that of low specific gravity. Ab-
normal urine exhibits greater fluctuations in color than that of
health. Red may indicate the presence of blood; a black color in-
dicates a certain form of cancer; green indicates jaundice, and
occurs sometimes in diabetes ; blue occurs in cholera and typhus.

4. Transparency. — Normal urine is transparent when voided,
becoming cloudy after standing, owing to the action of bacteria.
Pathological urine is often cloudy when first obtained, due to the
action of bacteria, the presence of blood, pus, etc., and the precipi-
tation of salts. Heat removes cloudiness due to precipitated urates,
but not when caused by bacteria., pus, or precipitated phosphates.
Acids will clear up any cloudiness due to precipitated phosphates,
but will increase turbidity arising from bacteria, albuminous casts,
and pus.

5. Chemical reaction, — This test consists in finding the action of
urine on litmus, an acid urine turning blue litmus red, and that
which is alkaline changing red to blue. Normal urine is acid, the
acidity being due to the acid sodium phosphate. Excessive acidity
is calculated to irritate the urinary passages and favors the forma-
tion of uric acid concretions. Alkalinity of the urine may be due
to the presence of ammonium carbonate (resulting from the de-
composition of urea by the agency of bacteria) or to an alkali of
sodium or potassium. In the former case the litmus paper turns
red again upon drying ; in the latter case it remains blue upon dry-
ing.

6. Specific gravity. — Normal urine (1,500 c.c.) has a specific
gravity ranging from 1.015 to 1.025, the average being 1.020, water
being taken as the standard. Low specific gravity may indicate
nephritis and organic albuminuria, though in functional albuminu-
ria the specific gravity is above normal. High specific gravity is
suggestive of melituria, and when it reaches 1.030 there is indicated

174 URINALYSIS.

the probable presence of sugar. The determination of specific
gravity is made with a urinometer.

7. Solids. — Xormal urine, when freshly voided, is free from visi-
ble solids, save a few epithelial scales. The visible solids of abnor-
mal urine may be estimated by means of the centrifuge. The quan-
tity of invisible solids in normal or pathological urine may be esti-
mated by multiplying the last two figures of the number represent-
ing the specific gravity by 2.33. This gives the number of grams
in a liter of the sample. Thus, in urine whose specific gravity is
1.030, the number of grams of solids held in solution would be
30X2.33, or 69.9 grams. The amount of solids eliminated by the
urine, 1,500 c.c. in twenty-four hours, would be represented by the
equation : 20 X 2. 33 X 1 . 5 = 69. 9 grams. The quantity of solids for
twenty-four hours is affected by age, diet, exercise, etc., the average
quantity for a person of 145 pounds being 61 grams. A reduction
of solids indicates renal diseases (with a tendency toward uraemia)
and defective elimination. The importance of knowing the amount
of urine passed in twenty-four hours is evident.

Laboratory exercise No. 66. — Make a physical examination of some
sample of urine, performing* all the tests indicated above.

2. CHEMICAL URINALYSIS.

1. Urea, CO (NH2)2. — The normal quantity of urea in the urine
is about one-half of all the solid constituents, or about 35 grams.
It is formed in the liver as the result of destructive metabolism of
the tissues and the splitting up of nitrogenous food principles. An
excess of urea occurs in acute diseases, such as fevers, in some liver
affections, such as diabetes, and accompanies excessive physical and
mental exertion, and indicates tissue waste A deficiency occurs in
chronic diseases. The average elimination of urea for an adult for
twenty-four hours is estimated at 33 grams. The percentage in the
urine is estimated by means of the Doremus ureometer as indicated
in the following method : Fill the long arm of the ureometer with
hypobromite. By means of the graduated pipette add 1 c.c. of
urine by compressing the nipple gently and steadily. The hypo-
bromite causes the liberation of nitrogen gas, which collects in the

CHEMICAL URINALYSIS. 175

upper end of the cylinder. The readings on the ureometer will in-
dicate the number of milligrams of urea in 1 c.c. ; from this deter-
mination may be calculated the total amount eliminated in twenty-
four hours.

Hypobromite may be prepared as follows : To 250 c.c. of water
add 100 grams of sodium hydrate. When ready to make the test,
add to 10 c.c of the sodium hydrate 1 c.c. of bromine, and then a
quantity of water equal to this mixture.

2. Uric acid. — Uric acid is a nitrogenous compound supposed to
be formed in the liver by the union of ammonia and lactic acid.
The quantity eliminated in twenty-four hours by the healthy adult
is about 0.5 gram. An excess occurs in leukaemia, fevers, lung and
heart diseases, tumors, etc.; an absence of uric acid occurs in
Bright's disease, gout, and other affections.

A qualitative test may be made by strongly acidulating with hy-
drochloric acid a beakerful of urine. After standing twenty-four
hours, uric acid crystals will be deposited, which may be examined
with the microscope.

3. Glucose. — Sugar occurs temporarily in the urine with such
diseases as cholera, gout, intermittent fever, etc. Its presence be-
comes persistent in diabetes. It may be detected by Fehling's solu-
tion, Haynes' test, fermentation test, etc.

Fehling's solution is prepared by dissolving 6.9 grams of copper
sulphate in 100 c.c. of distilled water. Then a second solution is
prepared by dissolving 34 grams of potassium sodium tartrate and
25 grams of potassium hydrate in 100 c.c. of water. In making the
test, place about 5 c.c. of each of these solutions in separate test
tubes, heat to boiling, and, after adding one to the other, add a few
drops of the suspected urine. If a yellowish-red precipitate is
formed, it indicates the presence of sugar.

Hay lies' solution is prepared by mixing 30 grains of copper sul-
phate with one-half ounce of distilled water, then adding one-half
ounce of pure glycerine, and, after mixing, adding five ounces of
liquor potassse The test is made by boiling five to ten cubic centi-
meters of this solution in a test tube, and adding six to eight drops

176 URINALYSIS.

of the suspected urine. Boil again, and, if sugar be present, a yel-
lowish-red precipitate will be formed.

A quantitative test for sugar may be made with the fermentation
saccharometer as follows: To 10 c.c. of urine add one gram of
Fleischmann's yeast; shake thoroughly in a test tube; pour the
mixture into the saccharometer. The yeast produces the decompo-
sition of the sugar with the formation of carbonic acid gas. The
quantity of gas evolved indicates the amount of sugar present, and
may be determined by the readings of the graduated scale.

4. Albumin. — The presence of albumin in urine may be due to
degeneration of the kidney tissues, excessive blood pressure, or an
increased diff usibility of the serum-albumin of the blood. It is prob-
ably more often due to kidney degeneration, and in such cases is in-
dicative of chronic albuminuria, known as Bright's disease. It may
be detected by the following methods :

(1) Heat Test. — Pour into a test tube about 10 c.c. of the sus-
pected urine; heat the upper portion to boiling. If a cloudiness
appears, which is not removed by nitric acid, albumin is present.

(2) Nitric Acid Test. — Pour into a test tube 5 c.c. of nitric acid;
then, with a pipette, add, drop by drop, some of the suspected urine,
allowing it to run down the side of the tube. If albumin is present,
a white ring will be formed at the plane of juncture of the two
fluids.

(3) Quantitative Test. — Using Esbach's albuminometer, fill the
tube with urine to the graduation U; then add the test solution
(10 grams picric acid, 20 grams citric acid, water to make one liter)
to fill the tube to graduation E. Cover the end of the tube and
shake the contents thoroughly: close the tube with rubber stopper,
and set aside for twenty-four hours. The precipitated albumin can
then be estimated from the graduated scale, each graduation indi-
cating one gram of albumin in a liter of urine.

5. Chlorides. — The quantity of chlorides eliminated by the urine
in twenty-four hours is from six to ten grams. When the amount
becomes less than five grams, it indicates weakness of digestion.
An excessive excretion occurs in diabetes, and is considered a favor-

CHEMICAL URINALYSIS. ITT

able sign in dropsical conditions. The presence of chlorides may
be tested by acidulating with nitric acid and adding silver nitrate.
A white precipitate of chlorides is formed.

Quantitative test: Dilute 10 c.c. of urine with 100 c.c. of water;
add a few drops of potassium chromate solution; then add slowly
a solution of silver nitrate (17 grams to a liter of water) until the
color of the solution changes from yellow to red. Each c.c. of silver
nitrate (standard solution) used will precipitate 0.00354 gram of
chlorine, from which may be estimated the percentage by weight
of chlorine in the urine.

6. Phosphates. — The earthy phosphates are those of calcium and
magnesium; the alkaline phosphates are those of sodium and potas-
sium ; triple phosphate is ammonio-magnesium phosphate ; the acid
phosphates of the alkalies give the acid reaction to the urine, and
are represented by the formulas NaH2 P04 and KH2 P04. An
excess of phosphates occurs in diabetes. A diminution generally
occurs in nephritis, gout, rheumatism, and acute infectious diseases.

The earthy phosphates may be detected by adding ammonium
hydrate and gently heating; a white precipitate is formed, which
is dissolved by the addition of acetic acid. A quantitative deter-
mination may be made by filling a test tube whose diameter is two
centimeters with urine to the depth of 5.3 centimeters; to this add
a few drops of ammonium hydrate and heat until the phosphates are
precipitated; set aside and in fifteen minutes examine. If the
height of sediment be 1 centimeter, the quantity of earthy phos,-
phates is normal, but diminished or increased if the height should
be less or greater than 1 centimeter.

To determine approximately the quantity of alkaline phosphates,
proceed as follows : Kemove the earthy phosphates by precipitation
and filtration, and to 10 c.c. of the filtered urine add 3 c.c. of mag-
nesium mixture. Magnesium fluid is prepared by dissolving magne-
sium sulphate and ammonium chloride, one part each, in eight parts
of distilled water and one part of ammonium hydrate. The amount
of turbidity formed by the precipitate indicates the quantity of

alkaline phosphates present. If it is simply milky, the quantity is
12

178 URINALYSIS.

normal; if heavy, increased; and if no precipitate, there is a de-
crease.

7. Sulphates. — The total amount of sulphuric acid in combina-
tion excreted by an adult in twenty-four hours is between two and
three grams. An increase of sulphates occurs in serious stoppages
of the food in the intestines, the pus forming diseases, as in fetid
bronchitis, diphtheria, etc., and in acute fevers, meningitis, and
rheumatism. They may be detected by adding to a portion of the
urine one-third the amount of barium chloride acidulated with hy-
drochloric acid. A white, milky precipitate indicates the presence
of sulphates. An approximate quantitative determination may be
made as follows : To 10 c.c. of urine add 3 c.c. of barium chloride
solution, which is prepared by mixing four parts of barium chloride,
one part of hydrochloric acid, and sixteen parts of distilled water.
If a milky turbidity results, the quantity of sulphates is normal;
if the precipitate is heavy, having the consistency of cream, it is in-
creased.

Laboratory exercise No. 67.— Chemical examination. Make an analy-
sis of a sample of urine by the chemical tests suggested above. Write
out your analysis in systematic form.

3. MICROSCOPICAL URINALYSIS.

The microscopical examination of urine is of value in confirming
the results of physical and chemical analyses and in throwing light
upon certain pathological conditions — light obtainable from no
other source. The sediments of urine may be organized or unorgan-
ized. Organized sediments comprise epithelium, blood, pus, tubu-
lar casts, spermatozoa, bacteria, and vermes. The unorganized
sediments comprise crystals of the phosphates, urates, etc., amor-
phous compounds, and inorganic concretions.

UNORGANIZED SEDIMENTS.

Among some of the forms of crystals which may be demonstrated
by microscopical urinalysis are those of calcium oxalate (Fig. 1),
triple phosphate (Fig. 2), uric acid (Fig. 3), leucin and tyrosin
(Fig. 4), nitrate of urea (Fig. 5), calcium sulphate (Fig. 6), cal-
cium phosphate (Fig. 7), and hamiin (Fig. 8).

UNORGANIZED SEDIMENTS.

Fig. 1 Fig. 2

Calcium Oxalate.

Triple Phosphate.

Fig. 3

Fig. 4

Uric Acid.

Fig. 5

Nitrate of Urea.

Fig, 7

Calcium Phosphate.

Fig. 6

Calcium Sulphate.

Fig. 8

Haemin Crystals.

[179]

180 URINALYSIS.

Amorphous sediments, such as mates, phosphates, etc., are of
occasional occurrence.

Laboratory exercise No. 68. — Organic sediments. Obtain some cys-
titic urine by means of a pipette; apply a drop of the sediment to the
slide; cover and search for epithelium, noting- the forms of the cells;
search also for pus and bacteria. Of what significance are these ele-
ments ?

Bacillus coli commune, Micrococcus urece, and the species of
Staphylococcus invariably occur in cystitic urine. What other ele-
ments do you observe ? Make a cover-glass preparation, and stain
with gentian- violet. Mount in water, and make a search for pus,
bacteria, epithelium, blood, crystals, and other structures.

Obtain samples of urine from cases of nephritis, Bright ?s disease,
etc. Examine the sediments by the usual method, and demonstrate
epithelium, blood casts, bacteria, etc., such as may be present.
Patty, granular, epithelial, and blood casts may be easily demon-
strated. Hyaline casts should be precipitated by means of a centri-
fuge. A drop of the sediment is placed upon a slide containing
a cell, covered, and then examined. The casts are of small or large
diameter and transparent.

Laboratory exercise No. 69. — Crystals. Allow cystitic urine to stand
for twenty-four hours. Examine some of the sediment and determine
the kinds of crystals present by comparing their forms with those of
the illustrations on page 179.

Clean five slips; upon each place a drop of urine. Allow the
first to dry without adding any reagent; to the second add a
small drop of ammonium hydrate; to the third, a drop of hydro-
chloric acid; to the fourth, nitric acid; and to the fifth, dilute sul-
phuric acid. When these preparations are dry, or nearly so, cover
and examine. Preparation No. 1 may exhibit crystals of calcium
oxalate, leucin, tyrosin, and uric acid ; No. 2 will exhibit crystals of
triple phosphate (Fig. 2) and calcium phosphate (Fig. 7) ; No. 3
may illustrate crystals of uric acid (Fig. 3) ; No. 4 will exhibit
nitrate of urea (Fig 5) ; and No. 5 will show crystals of calcium
sulphate ( Fig. 6 ) . Determine any other forms which may be ob-
served.

ORGANIZED SEDIMENTS. 181

ORGANIZED SEDIMENTS.

1. Epithelium. — Epithelium occurs in urine as isolated cells; or,
occasionally, groups of attached cells may be demonstrated. In
normal urine there is always a limited number of epithelial cells
due to ordinary desquamation, but under pathological conditions
the number becomes greatly increased. This may be due to inflam-
mation, suppuration, friction, and the action of bacteria. The
elements from the renal tubules are generally small round cells,
columnar or cuboidal cells ; those from the excretory duct are of the
tall columnar variety ; and those from the pelvis, ureter, and blad-
der are of the transitional type, exhibiting irregular forms — spindle-
shaped, polyhedral, and large round cells, some having more than
one nucleus, and some exhibiting pointed processes ; cells from the
prostatic portion of the urethra are of the squamous type, while
those from the free portion are low columnar cells. In the female,
squamous epithelium lines the entire urethra.

2. Blood (Fig. 10). — Blood occurs only in pathological urine;
it may be detected microscopically by the presence of the red disks.
These are known by their form and the absence of nuclei ; they sel-
dom form in rouleaux, but often exhibit crenation. Tuberculosis
of the kidneys, pyelitis, cystitis, and other affections are suggested
by the presence of blood.

3. PUB (Figs. 9 and 14). — Pus consists of dead or dying leuco-
cytes, which have escaped from the vascular channels. Leucocytes
are concerned in repairing diseased tissues and the destruction of
microbes. \7ast numbers die in the conflict, and these constitute
pus. Pus cells may be distinguished from other elements by their
size, granular appearance, and nuclei. They often contain several
nuclei in each cell and occasionally exhibit amoeboid movement.
Pus is invariably present in cystitis, gonorrhcea, tuberculosis, etc.

4. Casts. — These originate in the renal tubules and comprise
several varieties : Blood casts, epithelial casts, granular casts, fatty
casts, and hyaline casts.

Blood casts (Fig. 13) are the result of hemorrhage in the urinary
tubules, and indicate such infections as haematuria, renal congestion,
and acute nephritis.

ORGANIZED SEDIMENTS.

Fig. 9

Fig. 10

o

Pus Cells.

1Z.4

Stf*« fi$f%

Blood.

Fig. 11

Fig. 12

Hyaline Casts.

Epithelial Casts.

Fig. 13

Fig. 14

Fig. 15

Blood Casts. Pus Showing Amoeboid Movement. Granular Casts.

[182]

ORGANIZED SEDIMENTS. 183

Epithelial casts (Fig. 12) result from the disintegration of the
epithelium of the renal tubules; their presence indicates nephritis
and other kidney infections.

Granular casts (Fig. 15) result from the disintegration • of pas,
epithelium, and blood, and are indicative of pathological conditions
of the kidney.

Fatty casts are the result of changes in the kidney which indicate
the destruction of the protoplasm of the cells.

Hyaline casts (Fig. 11) are probably produced by the coagulation
of certain elements of the blood which have gained access to the
renal tubules. They are almost colorless and difficult of demon-
stration; their presence indicates interstitial-nephritis.

5. Bacteria. — Normal urine is free from bacteria, The species
most commonly met with in pathological urine are Micrococcus
urece, Staphylococcus pyogenes aureus, albus, and citreus, Strepto-
coccus pyogenes and Bacillus coli commune. Bacillus tuberculosis
is of occasional occurrence. These organisms can be demonstrated
by the usual methods of staining.

6. Vermes. — Two species of vermes are of occasional occurrence
— namely, Distoma hwrnatobium and Filaria sanguinis Jiominis.

Laboratory exercise No. 70. — Make a complete analysis of some sam-
ple of urine, and fill out the form presented on pages 184-185.

MEMORANDA.

184

URINALYSIS.
ANALYSIS OF URINE.

Sample

Physical Tests.

f Normal urine

1. Amount in 24 hours. . <

^ Sample examined . .

f Normal urine

2. Odor j

(_ Sample tested

( Normal urine

3. Color •{

t Sample

f Normal urine

4. Transparency <^

t Sample

f Normal urine

5. Chemical reaction . . . -j

[ Sample

f Normal urine

6. Specific gravity «j

[ Sample

f Normal
f Visible... <|

[_ Sample

7. Solids <[

f Normal
^ Invisible . <

[ Sample

Chemical Tests.

f Normal

1. Urea <^

[ Sample

f Normal

2. Uric acid •{

t Sample

f Normal

3. Glucose <

[ Sample .

f Normal

4. Albumin <j

t Sample

ANALYSIS OF URINE.

185

5. Chlorides.

6. Phosphates.

7. Sulphates

Normal
Sample

Earthy ..

Normal

Sample

f Normal
I Alkaline . \

[ Sample

f Normal
[ Sample

Microscopical Tests.

Small round cells ,

Tall columnar

1. Epithelium •{ Transitional ,

Squamous

Low columnar

2. Blood

3. Pus

f Blood casts

Epithelial

4. Casts 4 Granular

Fatty

Hyaline....

5. Bacteria ,

6. Spermatazoa

7. Crystals

8. Amorphous sediments

Clinical Significance of Examination.

Respectfully,

Date

19.

INDEX.

PAGE

Abbreviations ............................ 28

Accessories ............................... 13

Adenoid tissue ........................... 68

Adepose tissue .................. ......... 67

Alimentary tract ......................... Ill

Amoeba ................................... 47

Areolar tissue ............. . .......... ____ 67

Arteries .................................. 93

Bacteria .................................. 143

Classification ........................ 144

Cultivation of ........................ 151

Distribution .......................... 149

Kinds ................................ 145

Morphology .......................... 145

Non-pathogenic .......... _____ ...... 160

Numbers ............................. 149

Pathogenic ........................... 164

Products ............................. 146

Size ..................... . ............ 149

Study of .............................. 153

Bacteriology ............... . ............. 143

Basement membrane ____ ........... . ..... 68

Balsam ................................... 34

Blood ..................................... 55

Bone ..................................... 70

Brain ..................................... 85

Brownian movement ..................... 42

Capillaries ............................... 94

Cartilage ................................. 69

Cell

35

Contents ............................. 38

Multiplication ....................... 40

Wall ................................. 37

Centering ................................ 19

Centrifuge ............................... 14

Cerebellum ............................... 86

Cerebrum .. ............. ____ ............. 87

Clearing .................................. 19

Connective tissue ..................... ... 66

Cowper's glands ......................... 136

Culture media ............................ 151

Dehydration ............................. 19

Dentine ......................... . ........ 72

Drawings ....................... . ........ 28

Ear ....................................... 142

Embedding ............................... 17

PAGE

Embryology 54

Endothelium 61

Epithelium 61

Euglsena 50

Eye 141

Fallopian tube 138

Fixation 18

Fixatives 32

Fixing 16

Germicides 170

Glands 101

Hair 107

Hanging-drop 153

Hardening 16

Heart 93

Immunity 170

Infiltrating 16

Injecting 20

Inoculation 152

Intestine 114

Irrigation 27

Kidney 131

Labeling 20

Leucocytes 56

Liver 118

Lungs 128

Lymphatic system 96

Medulla oblongata 86

Membranes 100

Micromillimeter 100

Microscope 8

Microscopic technique 16, 156

Microtome 20

Mould 154

Mounting 20

Muscle 75

Nails 107

Nerve endings 88

Nervous systems 81

Nervous tissues 79

Nose 142

(Esophagus 113

[1871

188

INDEX.

PAGE

Organs 53

Ovary 137

Pancreas 103

Parotid gland 102

Parovarium 138

Penis 137

Plasraodium malariae 57

Plating 52

Prostate gland 136

Protococcus 44

Protoplasm 37

Reagents 30

Reproduction 40

Sebaceous gland 108

Sectioning 18

Skin 106

Slipper animalcule 49

Spleen 98

Spinal cord 81

Spirogyra 46

Staining 19

PAGE

Staining methods 23, 157

Stains 30

Stomach 113

Sweat glands 108

Sympathetic system 88

Teeth 122

Testis 135

Thymusbody 98

Tissues 20, 53

Tongue 121

Tonsils 98

Toxins 170

Ureters 133

Urethra 133

Uterus 138

Urinalysis 172

Vagina 139

Veins 94

Yeast... .. 43

MEMORANDA.

MEMORANDA.

MEMORANDA.

MEMORANDA.

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