THE MICROSCOPIST.

•IOLOGY
LIBRARY

ZENTMAYER'S AMERICAN CENTENNIAL STAND

THE

MICROSCOPIST:

MANUAL OF MICROSCOPY,

AND

COMPENDIUM OF THE MICROSCOPIC SCIENCES; MICRO-
MINEKALOGY, MICKO-CHEMISTEY, BIOLOGY, HIS-
TOLOGY, AND PRACTICAL MEDICINE.

FOURTH EDITION,
GREATLY ENLARGED,

WITH

TWO HUNDRED AND FIFTY-TWO ILLUSTRATIONS.

BY

J. H. WYTHE, A.M., M.D.,

PROFESSOR OF MICROSCOPY AND HISTOLOGY IN THE MEDICAL COLLEGE OP THE
PACIFIC, SAN FRANCISCO, CAL.

PHILADELPHIA:
LINDSAY & BLAKISTON.

1880.

Entered, according to Act of Congress, in the year 1880,

By LINDSAY & BLAKISTON,
In the Office of the Librarian of Congress, at Washington, D. C.

SHERMAX & CO., PRINTERS,
PHILADELPHIA.

•* 4T,

KESPECTFULLY DEDICATED

TO THE

SAN FRANCISCO MICROSCOPICAL SOCIETY,

AS A TESTIMONY

TO THE

ZEAL AND INDUSTRY OF ITS MEMBERS

IN

THE PROSECUTION

OF

MICROSCOPIC SCIENCE.

PREFACE.

THE first and second editions of this work, in 1851 and
1853, were intended to furnish a manual on the use of the
microscope for physicians and naturalists. The third and
present editions aim to be also a compendium of the micro-
scopic sciences, but as microscopy reaches its climax in prac-
tical medicine this branch of study receives the largest
attention. Matters of mere curiosity have been but briefly
referred to, while every necessary fact or principle relating to
the microscope has been carefully stated and classified.

By the liberality of the publishers, the chapters on the use
of the microscope in Pathology, Diagnosis, and Etiology,
which have been added to this edition, have been largely illus-
trated with woodcuts from Kindfleisch.

The Index and Glossary have been combined in this edition
so as to be a source of valuable information, and notices of
recent additions to the microscope, together with the genera of
microscopic plants, have been given in an Appendix.

No pains have been spared to render this manual a useful
companion to the student of Nature, and an aid to the progress
of real science.

July, 1880.

CONTENTS.

CHAPTER I.
HISTORY AND IMPORTANCE OF MICROSCOPY.

Application of the Microscope to Science and Art — Progress of Micros-
copy, 17-21

CHAPTER II.
THE MICROSCOPE.

The Simple Microscope — Chromatic and Spherical Aberration — Compound
Microscope — Achromatic Object-glasses — Eye-pieces — Mechanical Ar-
rangements— Binocular Microscope, ..... 21-32

CHAPTER III.
MICROSCOPIC ACCESSORIES.

Diaphragms— Condensers — Oblique Illuminators — Dark-ground ditto — Il-
lumination of Opaque Objects— Measuring and Drawing Objects —
Standards of Measurement — Moist Chamber — Gas Chamber — Warm
Stage — Polariscope — Microspectroscope — Nose-piece — Object-finders —
Micro-photography, . 32-48

CHAPTER IV.

USE OF THE MICROSCOPE.

Care of the Instrument— Care of the Eyes — Table — Light — Adjustments —
Errors of Interpretation — Testing the Microscope, . . . 48-58

X CONTENTS.

CHAPTEE V.

MODERN METHODS OF EXAMINATION.

Preliminary Preparation of Objects — Minute Dissection — Preparation of
Loose Textures — Preparation by Teasing — Preparation by Section —
Staining Tissues — Injecting Tissues — Preparation in Viscid Media —
Fluid Media — Indifferent Fluids — Chemical Eeagents — Staining Fluids
— Injecting Fluids — Preservative Fluids — Cements, . . 58-76

CHAPTEE VI.

MOUNTING AND PRESERVING MICROSCOPIC OBJECTS.

Opaque Objects — Cells — Dry Objects — Mounting in Balsam or Dammar —
Mounting in Fluid— Cabinets — Collecting Objects — Aquaria, 76-83

CHAPTEE VII.

THE MICROSCOPE IN MINERALOGY AND GEOLOGY.

Preparation of Specimens — Examination of Specimens — Crystalline Forms
— Crystals within Crystals— Cavities in Crystals — Use of Polarized
Light — Origin of Eock Specimens — Materials of Organic Origin —
Microscopic Palaeontology, 84-98

CHAPTEE VIII.
THE MICROSCOPE IN CHEMISTRY.

Apparatus and Modes of Investigation — Preparation of Crystals for the
Polariscope — Use of the Microspectroscope — Inverted Microscope —
General Micro-chemical Tests — Determination of Substances — Al-
kalies— Acids — Metallic Oxides — Alkaloids — Crystalline Forms of
Salts, 98-115

CHAPTEE IX.
THE MICROSCOPE IN BIOLOGY.

Theories of Life — Elementary Unit or Cell — Cell-structure and Formation
— Phenomena of Bioplasm — Movements of Cells — Microscopic Dem-
onstration of Bioplasm — Chemistry of Cells and their Products — Va-
rieties of Bioplasm — Cell-genesis — Eeproduction in Higher Organisms
— Alternation of Generations — Parthenogenesis — Transformation and
Metamorphosis — Discrimination of Living Forms, . . 116-127

CONTENTS. XI

CHAPTEK X.

THE MICROSCOPE IN VEGETABLE HISTOLOGY AND BOTANY.

Molecular Coalescence — Cell-substance in Vegetables — Cell-wall or Mem-
brane— Ligneous Tissue — Spiral Vessels — Laticiferous Vessels — Sili-
ceous Structures — Formed Material in Cells — Forms of Vegetable Cells
— Botanical Arrangement of Plants — Fungi — Protophytes — Desmids —
Diatoms — Nostoc — Oscillatoria — Examination of the Higher Crypto-
gamia — Examination of Higher Plants, .... 128-157

CHAPTER XL

THE MICROSCOPE IN ZOOLOGY.

Monera — Rhizopods — Infusoria — Rotatoria — Polyps — Hydroids — Acalephs
— Echinoderms — Bryozoa — Tunicata — Conchifera — Gasteropoda —
Cephalopoda — Entozoa — Annulata — Crustacea — Insects — Arachnida —
Classification of the Invertebrata, . . . , . . 158-182

CHAPTER XII.

THE MICROSCOPE IN ANIMAL HISTOLOGY.

Histo-chemistry — Histological Structure — Simple Tissues — Blood — Lymph
and Chyle — Mucus — Epithelium — Hair and Nails — Enamel — Connec-
tive Tissues — Compound Tissues — Muscle — Nerve — Glandular and
Vascular Tissue — Development of the Tissues — Digestive and Circu-
latory Organs — Secretive Organs — Respiratory Organs — Generative
Organs — Locomotive Organs — Sensory Organs — Organs of Special
Sense— Suggestions for Practice, 182-226

CHAPTER XIII.

THE MICROSCOPE IN PATHOLOGY.

Preparation of Specimens — The Appearance of Tissues after Death — De-
generation of Tissues — The Metamorphoses — The Infiltrations — In-
flammation— Resolution and Organization — Pathological New Forma-
tions— New Formation of Pathological Cells — Pathological Growths of
Higher Animal Tissues — Pathological Growths of Connective Tissue
Origin— Pathological Growths of Epithelial Origin, . . 226-295

Xll CONTENTS.

CHAPTER XIV.
THE MICROSCOPE IN DIAGNOSIS.

The Blood in Disease — Examination of Urine — Urea — Chlorides — Bile —
Albumen — Sugar — Urinary Deposits — Epithelium-^Mucus and Pus —
Blood — Spermatozoa — Bacteria, Fungi, etc. — Tube-casts — Crystalline
and Amorphous Deposits — Pus and Mucus in Diagnosis — Examination
of Milk — Saliva and Sputum — Vomited Matters — Intestinal Discharges
— Vaginal Discharges, 295-320

CHAPTEE XV.

THE MICROSCOPE IN ^ETIOLOGY.

Examination of the Air — Examination of Soil and Water — Examination
of Food, etc. — Parasites— Vegetable Parasites or Epiphytes— Fungi —
Dust or Germ Fungi, Conio or Gymnomycetes — Filamentous Fungi,
Hyphomycetes — Cleft Fungi, Schizomycetes — Mould Diseases— Fungi
of True Parasitic Diseases of the Skin and Mucous Membranes —
Fungi as Excitors of Fermentation and Putrefaction and Causes of
Disease — Animal Parasites — Protozoa — Vermes — Arthropoda — Dis-
ease Germs, 321-344

APPENDIX — Improvements in Microscopes and in Preparations — Genera
of Cryptogamia, 345-399

INDEX AND GLOSSARY, . . . . . , 401-434

THE MICROSCOPIST.

CHAPTER I.

HISTORY AND IMPORTANCE OF MICROSCOPY.

THE term microscopy, meaning the use of the micro-
scope, is also applied to the knowledge obtained by this
instrument, and in this "sense is commensurate with a
knowledge of the minute structure of the universe, so far
as it may come under human observation. Physics and
astronomy treat of the general arrangement and motions
of masses of matter, chemistry investigates their constitu-
tion, and microscopy determines their minute structure.
The science of histology, so important to anatomy and
physiology, is wholly the product of microscopy, while
this latter subject lends its aid to almost every other
branch of natural science.

To the student of physical phenomena this subject un-
folds an amazing variety developed from most simple
beginnings, while to the Christian philosopher it gives the
clearest evidence of that Creative Power and Wisdom
before whom great and small are terms without meaning.

In the arts, as well as in scientific investigations, the
microscope is used for the examination and preparation of
delicate work. The jeweller, the engraver, and the miner
find a simple microscope almost essential to their employ-
ments. This application of the magnifying power of lenses
was known to the ancients, as is shown by the glass lens

2

18 THE MICROSCOPIST.

found at Mneveh, and by the numerous gems and tablets
so finely engraved as to need a magnifying glass to detect
their details.

In commerce, the microscope has been used to detect
adulterations in articles of food, drugs, and manufactures.
In a single year $60,000 worth of adulterated drugs was
condemned by the New York inspector, and, so long as
selfishness is an attribute of degraded humanity, so long
will the microscope be needed in this department.

In agriculture and horticulture microscopy affords valu-
able assistance. It has shown us that mildew and rust in
wheat and other food-grains, the " potato disease," and
the " vine disease," are dependent on the growth of minute
parasitic fungi. It has also revealed many of the minute
insects which prey upon our grain-bearing plants and fruit
trees. The damage wrought by these insects in the United
States alone has been estimated by competent observers
as not less than three hundred millions of dollars in each
year. The muscardine, which destroys such large num-
bers of silk-worms in France and other places, is caused
by a microscopic fungus, the Botrytis bassiana.

The mineralogist determines the character of minute
specimens or of thin sections of rock, and the geologist
finds the nature of many fossil remains by their magnified
image in the microscope.

The chemist recognizes with this instrument excessively
minute quantities and reactions which would otherwise
escape observation. Dr. Wormley shows that micro-
chemical analysis detects the reaction of the 10,000th to
the 100,000th part of a grain of hydrocyanic acid, mer-
cury, or arsenic, and very minute quantities of the vege-
table alkaloids may be known by a magnified view of their
sublimates. The micro-spectroscope promises still more
wonderful powers of analysis by the investigation of the
absorption bands in the spectra of different substances.

In biology the wonderful powers of the microscope find

HISTORY AND IMPORTANCE OF MICROSCOPY. 19

their widest range. If we see not life itself, we see its
first beginnings, and the process of its development or
manifestation. If we see not Nature in her undress, we
trace the elementary warp and woof of her mystic drapery.

In vegetable and animal physiology we see, by its
means, not only the elementary unit^the foundation-stone
of the building — but also chambers and laboratories in
the animated temple, which we should never have sus-
pected— tissues and structures not otherwise discoverable
— not to speak of species innumerable which are invisible
to the naked eye.

In medical science and jurisprudence the contributions
of microscopy have been so numerous that constant study
in this department is needed by the physician who would
excel or even keep pace with the progress of his profes-
sion. Microscopy may be truly called the guiding genius
of medical science.

Even theology has its contribution from microscopy.
The teleological view of nature, which traces design, re-
ceives from it a multitude of illustrations. In this de-
partment the war between skeptical philosophy and theol-
ogy has waged most fiercely ; and if the difference between
living and non-living matter may be demonstrated by the
microscope, as argued by Dr. Beale and others, theology
sends forth a paean of victory from the battlements of this
science.

The attempts made by early microscopists to determine
ultimate structure were of but little value from the im-
perfections of the instruments employed, the natural mis-
takes made in judging the novel appearances presented,
and the treatment to which preparations were subjected.
In late years the optical and mechanical improvements in
microscopes have removed one source of error, but other
sources still remain, rendering careful attention to details
and accurate judgment of phenomena quite essential. Care-
ful manipulation and minute dissection require a knowledge

20 THE MICROSCOPIST.

of the effects of various physical and chemical agencies, a
steady hand, and a quick-discerning eye. Above all,
microscopy requires a cultured mind, capable of readily
detecting sources of fallacy, and such a love of truth as
enables a man to free himself from all preconceived no-
tions of structure and from all bias in favor of particular
theories and analogies. What result is it possible to draw
from the observations of those who boil, roast, macerate,
putrefy, triturate, and otherwise injure delicate tissues,
except for the purpose of isolating special structures or
learning the effects of such agencies ? Yet many of the
phenomena resulting from such measures have been de-
scribed as primary, and theories of development have been
proposed on the basis of such imperfect knowledge.

Borelli (1608-1656) is considered to be the first who
applied the microscope to the examination of animal
structure. Malpighi (1661) first witnessed the actual cir-
culation of the blood, which demonstrated the truth of
Harvey's reasoning. He also made many accurate obser-
vations in minute anatomy. Lewenhoeck, Swammerdam,
Lyonet, Lieberkuhn, Hewson, and others, labored also in
this department. When we remember that these early
laborers u;ed only simple microscopes, generally of their
own construction, we must admire their patient industry,
skilful manipulation, and accurate judgment. In these
respects they are models to all microscopists.

Within the last quarter of a century microscopic ob-
servers may be numbered by thousands, and some have
attained an eminent reputation. At the present day, in
Germany, England, France, and the United States, the
most careful and elaborate investigations are being made,
older observations are repeated and corrected, new discov-
eries are rapidly announced, and the most hidden recesses
of nature are being explored.

It is proposed in this treatise to give such a resume of
microscopy as shall enable the student in any department

THE MICROSCOPE. 21

to pursue original investigations with a general knowl-
edge of what has been accomplished by others. To this
end a comprehensive view of the necessary instruments
and details of the art, or what the Germans call technol-
ogy, is first given, and then a brief account of the appli-
cation of the microscope to various branches of science,
especially considering the needs of physicians and stu-
dents of medicine.

CHAPTER II.

THE MICROSCOPE.

The Simple Microscope. — The magnifying power of a
glass lens (from lens, a lentil ; because made in the shape
of its seeds) was doubtless known to the ancients, but only
in modern times has it been applied in scientific research.

The forms of lenses generally used are the double convex,
with two convex faces ; piano convex, with one face flat
and the other convex ; double concave, with two concave
faces ; plano-concave, with one flat and one concave face ;
and the meniscus, with a concave and a convex face.

In the early part of the seventeenth century very mi-
nute lenses were used, and even small spherules of glass.
Many of the great discoveries of that period were made
by these means. A narrow strip of glass was softened in
the flame of a spirit-lamp and drawn to a thread, on the
end of which a globule was melted and placed in a thin
folded plate of brass, perforated so as to admit the light.
Some of these globules were so small as to magnify sev-
eral hundred diameters. Of course, they were inconve-
nient to use, and larger lenses, ground on a proper tool,
were more common.

The magnifying power of lenses depends on a few simple

22 THE MICROSCOPIST.

optical laws, concerning refraction of light, allowing the
eye to see an object under a larger visual angle ; so that
the power of a simple microscope is in proportion to the
shortness of its focal length, or the distance from the lens
to the point where a distinct image of the object is seen.
This distance may be measured by directly magnifying
an object with the lens, if it be a small one, or by casting
an image of a distant window, candle, etc., upon a paper
or wall. The focus of the lens is the point where the
image is most distinct. Different persons see objects
naturally at different distances, but ten inches is consid-
ered the average distance for the minimum of distinct
vision. A lens, therefore, of two inches focal length,
magnifies five diameters ; of one inch focus, ten diameters ;
of one-half inch, twenty diameters ; of one-eighth inch,
eighty diameters ; etc.

Simple microscopes are now seldom used, except as
hand magnifiers, or for the minute dissection and prepa-
ration of objects. They are used for the latter purpose,
when suitably mounted with a convenient arm, mirror,
etc., because of the inconvenience of larger and otherwise
more perfect instruments.

Single lenses, of large size, are also used for concentra-
ting the light of a lamp on an object during dissection, or
on an opaque object on the stage of a compound micro-
scope.

There are imperfections of vision attending the use of
all common lenses, arising from the spherical shape of the
surface of the lens, or from the separation of the colored
rays of light when passing through such a medium.
These imperfections are called respectively spherical and
chromatic aberration. To lessen or destroy these aberra-
tions, various plans have been proposed by opticians. For
reducing spherical aberration, Sir John Herschel pro-
posed a doublet of two plano-convex lenses, whose focal
lengths are as 2.3 to 1, with their convex sides together ;

THE MICROSCOPE. 23

and Mr. Coddington invented a lens in the form of a
sphere, cut away round the centre so as to assume the
shape of an hour-glass. This latter, in a convenient set-
ting, is one of the best pocket microscopes. Dr. Wollas-
ton's doublet consists of two plano-convex lenses, whose
focal lengths are as 1 to 3, with the plane sides of each
artd the smallest lens next the object. They should be

FIG. 1.

Holland's Triplet.

about the difference of their focal lengths apart, and a
diaphragm or stop — an opaque screen with a hole in it —
placed just behind the anterior lens. This performs ad-
mirably, yet has been further improved by Mr. Holland
by making a triplet of plano-convex lenses (Fig. 1), with
the stop between the upper lenses.

The Compound Microscope consists essentially of two
convex lenses, placed some distance apart, so that the
image made by one may be magnified by the other.
These are called the object-glass and the eye-glass. In
Fig. 2, A is the object-glass, which forms a magnified
image at c, which is further enlarged by the eye-glass B.
An additional lens, D, is usually added, to enlarge the
field of view. This is called the field-glass. Its office, as
in the figure, is to collect more of the rays from the
object-glass and form an image at F, which is viewed by
the eye-glass.

Owing to chromatic aberration, an instrument of this
kind is still imperfect, presenting rings of color round the
edge of the field of view as well as at the edge of the
magnified image of an object, together with dimness and

24 THE MICROSCOPIST.

confusion of vision. This may be partly remedied by a
small hole or stop behind the object-glass, which reduces
the aperture to the central rays alone, yet it is still un-

FIG. 2.

Compound Microscope.

satisfactory. Some considerable improvement may result
from using Wollaston's doublet as an object-glass, but the

THE MICROSCOPE.

25

achromatic object-glasses now supplied by good opticians
leave nothing to be desired.

Objed-glasses. — A general view of an achromatic object-
glass is given in Fig. 3. It is a system of three pairs of
lenses, 1, 2, 8, each composed of a double convex of crown
glass and a plano-concave of flint, a, 6, c, represents the
angle of aperture, or the cone of rays admitted. It is
unnecessary to consider the optical principles which un-
derlie this construction. Different opticians have different
formulae and propose various arrangements of lenses, and
there is room for choice among the multitude of micro-
scopes presented for sale. For high powers, the German

FIG. 3.

FIG. 4.

Achromatic Object-glass.

Huygenian Eye-piece.

and French opticians have lately proposed a principle of
construction which is known as the immersion system.
It consists in the interposition of a drop of water between
the front lens of the objective and the covering glass over
the object. This form of object-glass is corning into gen-
eral use. For the more perfect performance of an objec-
tive, it is necessary that it should be arranged for correct-
ing the effect of different thicknesses of covering glass.
This is accomplished by a fine screw movement, which
brings the front pair of lenses (1, Fig. 3) nearer or further
from the object. In this way the most distinct and accu-
rate view of an object may be obtained.

26 THE MICROSCOPIST.

Eyepieces. — The eye-piece usually employed is the Huy-
genian, or negative eye-piece (Fig. 4). This is composed
of two plano-convex lenses, with their plane sides next
the eye. Their focal lengths are as 1 to 3, and their
distance apart half the sum of their focal distances.
Several of these, having different magnifying powers, are
supplied with good microscopes. It is best to use a weak
eye-piece, increasing the power of the instrument by
stronger objectives when necessary. Kellner's eye-piece
has the lens next the eye made achromatic. The peri-
scopic eye-piece of some of the German opticians has both
lenses double convex. This gives a larger field of view
with some loss of accurate definition. For high powers,
I have used a strong meniscus in place of the lower lens
in the Huygenian eye-piece. Dr. Royston Pigott has
suggested improvements in eye-pieces by using an inter-
mediate Huygenian combination, reversed, between the
objective and ordinary eye-piece. This gains power, but
somewhat sacrifices definition. Still better, he has pro-
posed an aplanatic combination, consisting of a pair of
slightly overcorrected achromatic lenses, mounted mid-
way between a low eye-piece and the objective. This
has a separating adjustment so as to traverse two or
three inches. The focal length of the combination varies
from one and a half to three-fourths of an inch. The
future improvement of the microscope must be looked for
in this direction, since opticians seem to have approached
the limit of perfection in high power objectives, some of
which have been made equivalent to g'gth or T^th of an
inch focal length. As an amplifier, I have used a double
concave lens of an inch in diameter and a virtual focus of
one and a half inches between the object-glass and the
eye-piece. If the object-glass be a good one, this will
permit the use of a very strong eye-piece with little loss
of defining power, and greatly increase the apparent size
of the object.

THE MICROSCOPE. 27

Meclianiml Arrangements. — The German and French
opticians devote their attention chiefly to the excellence
of their glasses, while the mechanical part of their instru-
ments is quite simple, not to say clumsy. They seem to
proceed on the principle that as little as possible should be
done by mechanism, which may be performed by the hand.
It is different with English and American makers, some
of whose instruments are the very perfection of mechan-
ical skill. The disparity in cost, however, for instruments
of equal optical power is quite considerable.

Certain mechanical contrivances are essential to every
good instrument. The German and French stands are
usually vertical, but it is an advantage to have one which
can be inclined in any position from vertical to horizontal.
There should be steady and accurate, coarse and fine ad-
justments for focussing ; a large and firm stage with ledge,
etc., and with traversing motions, so as to follow an object
quickly, or readily bring it into the field of view ; also a
concave and plane mirror with universal joints, capable
of being brought nearer or farther from the stage, or of
being turned aside for oblique illumination. Steadiness,
or freedom from vibration, is of the utmost importance in
the construction, since every unequal vibration will be
magnified by the optical power of the instrument.

Among so man}7 excellent opticians it would be impos-
sible to give a complete list of names whose workmanship
is wholly reliable, yet among the foremost may be men-
tioned Tolles, of Boston ; Wales, of Fort Lee, ST. J. ; Gru-
now, of New York ; and Zentmayer, of Philadelphia ;
Powell & Leland, Ross and Smith, Beck & Beck, of London ;
Hartnack and Cachet, of Paris ; Merz, of Munich ; and
Gundlach, of Berlin. The optical performance of lenses
from these establishments is first class, and the mechanical
work of their various models good. The finest instru-
ments from these makers, with complete appliances, are
quite costly, except the Germans and French, whose ar-

W THE MICROSOOPIST.

rangements, as we have said, are more simple. Cheaper
instruments, however, are made by English and American
opticians, some of which are very fine.

Opticians divide microscopes into various classes, ac-
cording to the perfection of their workmanship or the
accessories supplied. The best first-class instruments have

FIG. 5.

Wenham's Prism for the Binocular Microscope.

a great variety of objectives and eye-glasses, mechanical
stage with rack-work ; a sub-stage with rack for carrying
various illuminators : a stand of most solid construction ;
and every variety of apparatus to suit the want or wish
of the observer. They are great luxuries, although not
essential to perfect microscopic work. The second class,
or students' microscopes, have less expensive stands, but
equal optical powers, with first-class instruments. The

FIG. 6.

Collins's Harley Binocular Microscope.

30 THE MICROSCOPIST.

third or fourth classes of instruments are intended for
popular and educational use, and are fitted not only with
stands of more simple workmanship, but with cheaper
lenses, although often very good. Some French achro-
matic objectives, adapted to this class, are suitable for all
but the very finest work.

Binocular Microscopes. — The principle of the stereoscope
has been applied to the microscope, so as to permit the
use of both eyes. The use of such an instrument with
low or medium powers is very satisfactory, but is less
available with objectives stronger than one-half inch focus.
There are two ways of accomplishing a stereoscopic effect
in the microscope. The first and most common is by
means of Wenham's prism (Fig. 5), placed above the ob-
jective, and made to slide so as to transform the binocular
into a monocular microscope.

The second mode is to place an arrangement of prisms
in the eye-piece, so as to refract one-half the image to the
right and the other half to the left, which are viewed by
the corresponding eyes. In either construction there is a
provision made for the variable distance between the eyes
of different observers. In the frontispiece is a representa-
tion of Zentmayer's grand American microscope, which
will afford a good idea of the external appearance of a
first-class binocular microscope. Students' and third-class
microscopes, as before said, are less complicated and of
more moderate cost. The mechanical and optical per-
formance of Zentmayer's large instrument leaves scarcely
anything to be desired. Instead of the more expensive
rack-work stage, a simple form, originally invented by Dr.
Keen, of Philadelphia, and copied by Nachet and others,
is often employed. It consists of a rotating glass disk, to
which is attached a spring, or a V-shaped pair of springs,
armed with ivory knobs, which press upon a glass plate
in the object-carrier. The motion is exceedingly smooth
and effective.

FIG. 8.

Beck's Large Compound Microscope.

Fio. 9.

Hartnack's Small Model Microscope.

Nachet's Inverted Microscope.

32 THE MICROSCOPIST.

Fig. 6 shows Collins's Harley binocular microscope, a
good second class instrument.

Fig. 7 represents Beck's large compound miscroscope
(monocular) ; and Fig. 8, Hartnack's small model micro-
scope, with the body made to incline.

Fig. 9, Cachet's inverted microscope, invented by Dr.
Lawrence Smith for chemical investigations.

CHAPTER III.

MICROSCOPIC ACCESSORIES.

IN addition to the object-glasses, eye-glasses, mirror,
and mechanical arrangement of the microscope, to which
reference was made in the last chapter, several accessory
instruments will be useful and even necessary for certain
investigations.

The. Diaphragm, for cutting off extraneous light when
viewing transparent objects, is generally needed. In some
German instruments it consists of a cylinder or tube, whose
upper end is fitted with a series of disks having central
openings of different sizes. The disk can be adjusted to
variable distances from the object on the stage so as to
vary its effects. English and American opticians prefer
the rotary diaphragm, which is of circular form, perforated
with holes of different sizes, and made to revolve under
the stage. The gradual reduction of light can be accom-
plished by the cylinder diaphragm, since when it is pushed
up so as to be near the stage it cuts off' only a small part
of the cone of rays sent upwards by the concave mirror,
but, when drawn downwards, it cuts off more.

Collins's Graduating Diaphragm, which is made with
four shutters, moving simultaneously by acting on a lever

MICROSCOPIC ACCESSORIES.

33

handle, so as to narrow the aperture, accomplishes the
end most perfectly. (Fig 10.)

Collins's New (jr. dilating Diaphragm.

Beck's Iris Diaphragm is a further improvement of this
sort.

Condensers. — The loss of light resulting from the em-
ployment of high powers has led to several plans for con-
densing light upon the object. Sometimes a plano-convex
lens, or combination of lenses, is made to slide up and
down under the stage. A Kellner's eyepiece, or some

FIG. 11.

Smith and Beck's Achromatic Condenser.

similar arrangement, especially if fitted with a special
diaphragm, containing slits and holes, some of the latter
having central stops, is of very great use. First-class in-
struments are fitted up with achromatic condensers (Fig.
11), carrying revolving diaphragms, some of whose aper-

3

34 THE MICROSCOPIST.

tures are more or less occupied by stops, or solid disks, so
as to leave but a ring of space for light to pass through.
The effect of these annular diaphragms is similar to an
apparatus for oblique illumination.

The Webster condenser is similar in its optical parts to
the Kellner eye-piece, and is provided with a diaphragm
plate, with stops for oblique illumination, as well as a

Webster's Condenser, with Graduating Diaphragms.

graduating diaphragm for the regulation of the central
aperture. This is a most useful accessory. (Fig. 12.)

Oblique Illuminators — Certain fine markings on trans-
parent objects can scarcely be made out by central illumi-
nation, but require the rays to come from one side, so as
to throw a shadow. Sometimes this is well accomplished
by turning the mirror aside from the axis of the micro-
scope, and sometimes by the use of one of the condensers
referred to above. Amici's prism, which has both plane
and lenticular surfaces, is sometimes used on one side and
under the stage, in lieu of the mirror. For obtaining
very oblique pencils of light the double hemispherical con-
denser of Mr. Reade has been invented. It is a hemi-
spherical lens of about one and a half inch diameter, with
its flat side next the object, surmounted by a smaller lens
of the same form, the flat side of which is covered with a
thin diaphragm, having an aperture or apertures close to

MICROSCOPIC ACCESSORIES.

35

its margin. These apertures may be V-shaped, extending
to about a quarter of an inch from the centre.

If the microscope has a mechanical stage, with rack-
work, or is otherwise too thick to permit the mirror to
be turned aside for very oblique illumination, Nachet's
prism will prove of service. I have also contrived a useful
oblique illuminator for this purpose, by cementing with
Dammar varnish a plano-convex lens on one face of a to-
tally-reflecting prism, and near the upper edge of the
other side (at 90°) an achromatic lens from a French trip-
let. The prism is made to turn on a hinge, so that an
accurate pencil of light may fall on the object at any
angle desired.

Dark-ground Illuminators. — Some beautiful effects are
produced, and the demonstration of some structures aided,
by preventing the light condensed upon the object from
entering the object-glass. In this way the object appears

FIG. 13.

FIG. 14.

Nobert's Illuminator.

Parabolic Illuminator.

self-luminous on a black ground. For low powers this
can be easily done by turning aside the concave mirror as
in oblique illumination, or by employing Noberfs illumi-
nator, which is a thick plano-convex lens, in the convex

36

THE MICROSCOPIST.

surface of which a deep concavity is made. The plane
side is next the object. This throws an oblique light all
round the object. A substitute for this, called a spot lens,
is often used, and differs only from Robert's in having a
central black stop on the plane side instead of a concavity
(Fig. 13). A still greater degree of obliquity suitable for
high powers must be sought by the use of the parabolic
illuminator (Fig. 14). This is usually a paraboloid of glass,
which reflects to a focus the rays which fall upon its inter-
nal surface, while the central rays are stopped.

Illuminators for Opaque Objects. — Ordinary daylight is
hardly sufficient for the illumination of opaque objects,

FIG. 15.

Bull's-eye Condenser.

so that microscopists resort to concentrated lamplight, etc.
Gas, paraffine, and camphene lamps, have been variously
modified for this purpose, but few are better than the Ger-

MICROSCOPIC ACCESSORIES. 37

man student's Argand lamp for petroleum or kerosene
oil, as it is called. To concentrate the light from such a
source a condensing lens is used, either attached to the
microscope or mounted on a separate stand. Sometimes
a bull's-eye condenser is used for more effective illumination
(Fig. 15). This is a large plano-convex lens of short focus,
mounted on a stand. For such a lens the position of least
spherical aberration is when its convex side is towards
parallel rays ; hence, in daylight, the plane side should be
next the object. But, if it is desired to render the diverg-

FIG. 16.

Parabolic Speculum.

ing rays of a lamp parallel, the plane side should be next
the lamp, and rather close to it. The use of this con-
denser will also commend itself, when used as last referred
to, in microscopic dissection. It will throw a bright light
from the lamp directly on the trough, watch-glass, etc., in
which the specimen is being prepared. The Lieberkuhn,
or a concave speculum attached to the object-glass, and
reflecting the light from the mirror directly upon the
object, is one of the oldest contrivances for the illumina-
tion of opaque objects ; but the most convenient instru-
ment is the parabolic speculum (Fig. 16), a side mirror with

38 THE MICROSCOPIST.

a parabolic surface attached to the objective. For
powers, a lateral aperture above the objective has been
made to throw the light down through the object-glass
itself by means of a small reflector, as devised by Prof.
Smith, or a disk of thin glass, as in Beck's vertical illumi-
nator. This latter is attached to an adapter interposed
between the objective and the body of the microscope.

Instruments for Measuring and Drawing Objects. — Screw
micrometers are sometimes used with the microscope, as
with the telescope, for the measurement of objects ; but
the less expensive and simpler glass micrometers have
generally superseded them. The latter are of two sorts,
the stage and the ocular micrometer. The stage micrometer
is simply a glass slide, containing fine subdivisions of the
inch, line, etc., engraved by means of a diamond point.
Jn case the rulings are TJi)ths and f ^ths of an inch, it
is evident that an object may be measured by comparison
with the divisions ; yet, in practice, it is found incon-
venient to use an object with the stage micrometer in this
way, and it will be found better to combine its use with
that of the drawing apparatus, as hereafter described.
The ocular, or eye-piece micrometer, is a ruled slip of glass
in the eye-piece. Its value is a relative one, depending on
the power of the objective and the length of the micro-
scope tube. By comparing the divisions with those of the
stage micrometer their value can be readily ascertained.
Thus, if five spaces of the eye-piece micrometer cover one
space of the stage micrometer, measuring T01(JIJth of an
inch, their value will be ^J^th of an inch each.

Different standards of measurement are used in different
countries. English and American microscopists use the
inch. In France, and generally in Germany, the Paris
line or the millimetre is used. The millimetre is 0.4433 of
a Paris line and 0.4724 of an English line ( ,!2th of an
inch).

In the French system the fundamental unit is the metre,

MICROSCOPIC ACCESSORIES.

39

which is the ten-millionth part of the quadrant of the
meridian of Paris. The multiples are made by prefixing
Greek names of numbers, and the subdivisions by prefix-
ing Latin names. Thus, for decimal multiples, we have
deco, hecto, kilo, and myrio ; and, for decimal subdivisions,
deci, centi, and milli. The following may serve for con-
verting subdivisions of the metre into English equiva-
lents :

A millimetre equals 0.03937 English inches.

A centimetre " 0.39371 "

A decimetre " 3.93708 "

One inch = 2.539954 centimetres, or 25.39954 millimetres.

'For drawing microscopic objects the camera lucida will
be found useful. This is a small glass prism attached to
the eye-piece. The microscope is inclined horizontally,

FIG. 17.

Oberhauser's Drawing Apparatus.

and the observer, looking into the prism, sees the object
directly under his eye, so that its outlines may be drawn
on a piece of paper placed on the table. Some practice,
however, is needed for satisfactory results. For the up-
right stands of German and French microscopes, the camera
lucida of Chevalier & Oberhauser is available. This is a
prism in a rectangular tube, in front of which is the eye-
piece, carrying a small glass prism (c, Fig. 17), surrounded

40 THE MICROSCOPIST.

by a black metal ring. 'A paper placed beneath is visible
through the opening in the ring, and the image reflected
by the prism upon it can be traced by a pencil. It is neces-
sary to regulate the light so that the point of the pencil
may be seen.

Dr. Beale has recommended, in lieu of the camera lucida,
a piece of slightly tinted plate glass (Fig. 18), placed in a
short tube over the eye-piece at an angle of 45°. This is
a cheap and effective plan. A similar purpose is served

Fio. 19.

Beale's Tint-glass Camera. Sceminering's Steel Disk.

by a little steel disk, smaller than the pupil of the eye,
placed at the same angle (Fig. 19).

The most simple method of measuring objects is to
employ one of the above drawing instruments, placing
first on the microscope stage an ordinary micrometer, and
tracing its lines on the paper. Then the outline of the
object can be traced and compared with the lines. The
magnifying power of an object-glass can also be readily
found by throwing the image of the lines in a stage
micrometer upon a rule held ten inches below the eye-
piece, looking at the magnified image with one eye and
at the rule with the other. Dr. Beale strongly urges
observers to delineate their own work on wood or stone,
since they can do it more exactly and truthfully than the

MICROSCOPIC ACCESSORIES. 41

most skilled artists who are unfamiliar with microscopic
manipulation.

Other accessory apparatus, such as a frog-plate, for more
readily observing the circulation in a frog's foot ; an
animalcule cage, or live box ; a compressorium, for apply-
ing pressure to an object ; fishing tubes ; watch-glasses ;
growing-slides, etc., will commend themselves on personal
inspection.

For preventing the evaporation of fluids during obser-
vation, Recklinghausen invented the moist chamber (Fig.
20), consisting of a glass ring on a slide, to which is fas-
tened a tube of thin rubber, the upper end of which is
fastened round the microscope tube with a rubber band.

FIG. 20.

JLiecklJiJgluuisen's Moist (. dumber.

A simpler form of moist chamber may be made by a
glass ring cemented on a slide. A few drops of water
cautiously put on the inner edge of the ring with a brush,
or a little moist blotting-paper may be placed inside. The
object (as a drop of frog's blood, etc.) may then be put on
a circular thin cover, which is placed inverted on the ring.
A small drop of oil round the edge of the cover keeps it
air and water-tight-
Somewhat similar to the above is Strieker's gas chamber
(Fig. 21). On the object-slide is a ring of glass, or putty,
with its thin cover. Through this ring two glass tubes
are cemented, one of which is connected with a rubber

42

THE MICROSCOPIST.

tube for the entrance of gas, while the other serves for
its exit.

For the study of phenomena in the fluids, etc., of warm-
blooded animals, we need, in addition to the moist cham-
ber, some way of keeping the object warm. This may be
roughly done by a perforated tin or brass plate on the
stage, one end of which is warmed by a spirit-lamp. A
piece of cocoa butter or wax will show by its melting
when the heat is sufficient. Schultze's warm stage is a
more satisfactory and scientific instrument. It is a brass
plate to fit on the stage, perforated for illumination, and
connected with a spirit-lamp and thermometer, so that

FIG. 21.

Strieker's Gas Chamber.

the amount of heat may be exactly regulated. Other
arrangements have been proposed to admit a current of
warm water, or for the passage of electricity through an
object while under observation, which are scarcely neces-
sary to describe.

The Polariscope. — The nature and properties of polarized
light belong rather to a treatise on optics or natural phi-
losophy than to a work like the present, yet a very brief
account may not be out of place. We premise, then, that
every ray or beam of common light is supposed to have
at least two sets of vibrations, vertical and horizontal.
As these vibrations have different properties, the ray when

MICROSCOPIC ACCESSORIES.

43

divided is said to be polarized, from a fancied resemblance
to the poles of a magnet. The division of the vibrations
may be effected (i. <?., the light may be polarized) in vari-
ous ways. For the microscope the polarizer is a Nichol's
prism, composed of a crystal of Iceland spar, which has
been divided and again cemented with Canada balsam, so
as to throw one of the doubly refracted rays aside from
the field of view (Fig. 22). Such a prism is mounted in
a short tube and attached to the under side of the stage.
In order to distinguish the effects of polarized light, an
analyzer is also needed. This usually consists of another

FIG. 22.

FIG. 23.

Nichol's Prism.

Polarizer and Analyzer.

similar NichoPs prism, attached either to the eye-piece or
just above the objective. The latter position gives a
larger field, but the former better definition. Fie;. 23
shows the polarizer and the analyzer. The polarizer is
improved by the addition of a convex lens next the object.
Hartnack has also improved the eye-piece analyzer by
adding a graduated disk and vernier.

When the polarizer and analyzer have been put in place,
they should be rotated until their polarizing planes are
parallel, and the mirror adjusted so as to give the most
intense light. If now the polarizing planes are placed at
right angles, by turning one of them 90°, the field is ren-

44

THE MICROSCOPIST.

dered dark, and doubly refracting bodies on the stage of
the microscope appear either illuminated or in colors. If
a polarized ray passes through a doubly refracting film,
as of selenite, it forms two distinct rays, the ordinary
and the extraordinary ray. Each of these will be of dif-
ferent colors, according to the thickness of the film. If
one be red, the other will be green, these colors being
complementary. By using the analyzer one of these rays
is alternately suppressed, so that on revolving the appa-
ratus the green and red rays appear to alternate at each
quarter of a circle. Films of selenite are often mounted
so as to revolve between the polarizer and the stage.
Darker's selenite stage is sometimes used for this purpose
(Fig. 24). With such a stage a set of selenites is usually

Fio. 24.

Darker's Selenite Stage.

supplied, giving the blue, purple, and red, with their com-
plementary colors, orange, yellow, and green. By this
combination all the colors of the spectrum may be ob-
tained. The selenite disks generally have engraved on
them the amount of retardation of the undulations of
white light, thus: J, }, and J. If these are placed so
that their positive axes (marked PA) coincide, they give
the sum of their combined retardations.

The Microspectroscope.— Ordinary spectrum analysis, by
determining the number and position of certain narrow
lines in the spectra of luminous bodies, called Fraunhofer's

MICROSCOPIC ACCESSORIES.

45

lines, enables the chemist to identify different substances.
The object of the microspectroscope is different. It en-
ables us to distinguish substances by the absence of cer-
tain rays in the spectrum, or, in other words, to judge of
substances by a scientific examination of their color. The
color of a body seen with the naked eye is the general
impression made by the transmitted light, and this may
be the same although the compound rays may differ

ii

The Sorby-Browning Microspectroscope.

greatly, so that colors which seem absolutely alike may
be distinguished by their spectra. Many solutions are
seen to absorb different colors in very definite parts of the
spectrum, forming absorption bands or lines, varying in
width and intensity according to the strength of the so-
lution. The instrument usually employed consists of a
direct-vision spectrum apparatus attached to the eye piece
of the microscope, which shows the principal Fraunhofer

46

THE MICROSCOPIST.

lines by daylight, or a spectrum of the light transmitted
by any object in the field of view. A reflecting prism is
placed under one-half of the slit of the apparatus so as to
transmit from a side aperture a standard spectrum for
comparison. In Fig. 25, A is a brass tube carrying the
compound direct-vision system of five prisms and an
achromatic lens. This tube is moved by the milled head

Fre. 2G.

Spectroscope with Micrometer.

B, so as to bring to a focus the different parts of the
spectrum. This is important when the bands or lines to
be examined are delicate. D is the stage on which objects
for comparison are placed. The light passing through
them from the mirror i, goes through a side opening to a
reflecting prism which covers a part of a slit in the bot-
tom of the tube A. This slit is opened and shut by means
of the screws c and H. Fig. 26 shows the internal ar-

MICROSCOPIC ACCESSORIES. 47

rangement of the prisms and lens, together with a microm-
eter for measuring the position of lines or absorption
bands. To use the microspectroscope, remove the tube
A, with the prisms, and insert the tube G in the place of
the eye-piece of the microscope. With the lowest power
object-glass which is suitable, and the slit opened wide by
the screw H, the object on the stage of the microscope,
illuminated by the mirror or condenser, is brought to a
focus, the tube A replaced and adjusted for focus by the
screw B, while the slit is regulated by c and H until a well-
defined spectrum is seen. To determine the position of
the absorption lines, remove the upper cover of the tube
A and replace it with that carrying the micrometer repre-
sented in Fig. 26. The mirror illuminates a transparent
line or cross, whose image is refracted by a lens c, mov-
able by a screw B, and reflected at an angle of 45° from
the upper surface of the prisms, so as to be seen upon the
spectrum. By means of the micrometer screw M, this is
made to move across the spectrum, so that the distance
between the lines may be determined. In order to com-
pare the results given by different instruments, the
observer should measure the position of the principal
Fraunhofer lines in bright daylight, and mark them on
a cardboard scale, which may be preserved for reference.
By comparing the micrometric measurement of lines in
the spectrum of any substance observed by artificial light
with such a scale, their position may readily be seen.

In using the microspectroscope some objects require a
diaphragm of small size, and others, especially with the
1J or 2-inch objective, a cap with a hole ,'gth of an inch
in diameter over the end of the microscope, to prevent
extraneous light from passing through the tube.

Nose-piece. — For the purpose of facilitating observations
with objectives of different powers a revolving nose-piece
has been contrived, carrying two, three, or four objectives,

48 THE MICROSCOPIST

which may he brought quickly into the axis of the instru-
ment.

Object-finders. — It is sometimes tedious to find a small
object on a slide, particularly with high powers, and a
number of contrivances, as Maltwood's finder, have been
proposed for this end. A very simple method, however,
may serve. Mark on the stage two crosses, one like the
sign of addition -}-, and the other like the sign of multi-
plication x , and, when the object is found, mark the slide
to correspond with the marks below. If the stage be a
mechanical one it will be necessary to arrange it in the
previous position.

Microscopic Photography. — Many European experimen-
ters have succeeded in taking microscopic photographs,
but a great advance in this direction has been made under
the direction of the medical department of the United
States army at Washington. Lieutenant-Colonel Wood-
ward has succeeded in furnishing permanent records of
many details of structure, which exhibit the very perfec-
tion of art. In a work like the present a full account of
the apparatus and methods employed would be out of place.
Dr. Beale's How to Work with the Microscope, and the re-
ports issued from the Surgeon-General's office at Wash-
ington, will give the details.

CHAPTER IV.

USE OF THE MICROSCOPE.

Care of the Instrument. — But little satisfaction will be
secured in microscopic work for any length of time with-
out scrupulous care of the lenses, etc., belonging to the
instrument, and habits of this kind should be early ac-
quired. When in frequent use the microscope should be

USE OF THE MICROSCOPE. 49

seldom packed away in its case, as a certain necessary
stiffness of motion in its various parts might thereby be
lessened. Yet it should be kept free from dust and damp.
A bell-s;lass cover, or glass case, or a cabinet which will
admit the reception of the instrument in a form ready for
immediate use, is desirable. Before using, the condition
of objective and eye-piece should be examined as well as
of the mirror, and dust or dampness removed. Another
examination should be made before the microscope is put
away.

Stains on the brass-work may be removed by a linen
rag, and dust on the mirror and lenses by a fine camel's-
hair brush, or very soft and clean chamois skin. Frequent
wiping will injure the polish of the lenses.

The upper surfaces of the lenses in the eye-pieces and
the mirror will need the most frequent attention The
objectives, if carefully handled and kept in their boxes
when not in use, will seldom require cleaning. If the front
of the objective becomes accidentally wet with fluid it
should be at once removed, and, when reagents are used,
great care should be taken to prevent contact with the
front of the lens.

Care of the Eyes.— Continuous observation, especially by
lamplight, and with high powers, has doubtless a ten-
dency to injure the sight. To cease work as soon as
fatigue begins is, however, a simple but certain rule for
protection. This time will vary greatly, according to the
general tone and vigor of the observer. It is also impor-
tant to use the eyes alternately if a monocular instrument
is employed, as otherwise great difference both in the
focus and in the sensitiveness of the eyes will result. The
habit of keeping the unemployed eye open is a good one,
and, though troublesome at first, is not difficult to ac-
quire. It is well to protect the eye from all extraneous
light, and to exclude every part of the object except that
which is under immediate observation. The diaphragm

4

50 THE MICKOSCOPIST.

will serve this end as well as modify the quality of the
light. For very delicate observations a dark shade over
the stage, which may be fastened by an elastic ring to
the microscope-tube, so as to shut off extraneous light,
will be useful.

Table, etc. — The microscopist's work-table should be
large and massive, so as to be convenient and free from
vibration. Drawers for accessories and materials used in
preparing and mounting objects are also desirable, as well
as a few bell-glasses for secluding objects from dust. Re-
agents should always be removed from the table after use
and kept in another place.

Light. — Dr. Carpenter has well said, " Good daylight is
to be preferred to any other kind of light, but good lamp-
light is preferable to bad daylight." A clear blue sky
gives light enough for low powers, but a dull white
cloudiness is better. The direct rays of the sun are too
strong, and should be modified by a white curtain, reflec-
tion from a surface of plaster of Paris, or, still better, by
passing through a glass cell containing a solution of am-
monio-sulphate of copper.

Various kinds of lamps have been contrived for micro-
scopic use ; among the best are the German and French
" student's reading lamps," which burn coal oil or petro-
leum. It is often useful to moderate such a light by the
use of a chimney of blue glass, or by a screen of blue glass
between the flame and the object. Dr. Curtis contrived
a useful apparatus, consisting of a short petroleum lamp
placed in an upright, oblong box. On one side of the box
is an opening occupied with blue glass ; on another side
the opening has ground-glass, as well as a piece colored
blue, and a plano-convex lens so placed as to condense the
light thus softened to a suitable place on the table.

As a general rule the light should come from the left
side, and that position assumed or inclination given to the
instrument which is most comfortable to the observer.

USE OF THE MICROSCOPE. 51

English and American microscopists prefer an inclined
microscope, while the German and French instruments
being usually vertical do not permit this arrangement.

Adjustment. — The details of microscopic adjustments
are only to be learned by practice, yet a few directions
may be instructive. The selection of the objectives and
eye-pieces depends on the character of the object. As a
general rule, the lowest powers which will exhibit an
object are the best. It is best to use weak eye-pieces with
the stronger objectives, yet much depends on the perfec-
tion of the glasses employed.

The focal adjustment can be made with the coarse ad-
justment or quick motion when low powers are employed ;
but for higher powers the line adjustment screw is essen-
tial. Care must be taken not to bring the objective into
close or sudden contact with the thin glass cover over the
object, and, in changing object-glasses, the microscope
body should be raised from the stage by the coarse adjust-
ment.

•The actual distance between the object and object-glass
is much less than the nominal focal length, so that the
1 inch objective has a working distance of about J an
inch, the Jth of about ^th of an inch, while shorter ob-
jectives require the object to be covered with the thinnest

Sometimes, in high powers, and especially with immer-
sion-lenses, an adjustment of the object-glass is necessary
in order to suit the thickness of the glass cover. With
thick covers the individual lenses must be brought nearer
to each other, and, with very thin covers, moved farther
apart.

If immersion-objectives be employed a drop of water is
placed on the glass cover with a glass rod or camel's-hair
pencil, and a second drop on the lens. The lens and object
are then approximated till the drops flow together and the
focus is adjusted. By turning the ecrew of the objective

52 THE MICROSCOPIST.

and using the fine adjustment the best position will be
shown by the sharper and more delicate image of the
object.

For other details respecting adjustment the reader is
referred to the chapter on Microscopic Accessories.

Errors of Interpretation. — True science is hindered most
of all by speculation and false philosophy, which often
assume its garb and name, but it is also retarded by im-
perfeet or false observation. It is much less easy to see
than beginners imagine, and still less easy to know what
we see. The latter sometimes requires an intellect of sur-
passing endowments. The sources of error are numerous,
but some require special caution, and to these we now
refer.

The nature of microscopic images causes error from
imperfect focal adjustment. We see distinctly only that
stratum of an object which lies directly in focus, and it is
seldom that all parts of an object can be in focus together.
Hence we only recognize at once the outline of an object,
but not its thickness, and, as the parts which are out of
focus are indistinct, we may readily fall into error. Glasses
vary much in this respect. Some have considerable pene-
trating and defining power even with moderate angular
aperture, and are better for general work than those more
perfect instruments which give paler images and only re-
veal their excellencies to the practiced microscopist.

Sometimes the focal adjustment leads to error on ac-
count of the reversal of the lights and shadows at differ-
ent distances. Thus the centres of the biconcave blood-
disks appear dark when in focus, and bright when a little
within the focus ; while the hexagonal elevations of a dia-
tom, as the Pleurosigma angulatum,&vs light when in focus,
with dark partitions, and dark when just beyond the
focus. From this we gather a means of discrimination,
since a convex body appears lighter by raising the micro-
scope, and a concave by lowering it.

USE OP THE MICROSCOPE. 53

The refractive power of the object, or of the medium in
which it lies, is sometimes a source of error. Thus a
human hair was long thought to be tubular, because of
the convergence of the rays of light on its cylindrical con-
vexity. A glass cylinder in balsam appears like a flat
band, because of the nearly equal refractive powers of
object and medium. The lacunae and canaliculse of bone
were long considered solid, because of the dark appear-
ance presented on account of the divergence of the rays
passing through them. Their penetration with Canada
balsam, however, proves them to be cavities. Air-bubbles,
from refraction, present dark rings, and, if present in a
specimen, seldom fail to attract the first attention of an
inexperienced observer. The difference between oil-globules
in water and water in oil, or air-bubbles, should be early
learned, as in some organized structures oil-particles and
vacuoles (or void spaces) are often interspersed. A globule
of oil in water becomes darker as the object-glass is de-
pressed, and lighter when raised ; while the reverse is the
case with water in oil, since the difference of refraction
causes the oil particles to act as convex lenses, and those
of water like concave lenses.

Other errors arise from the phenomena of motion visible
under the microscope. A dry filament of cotton, or other
fabric absorbing moisture, will often oscillate and twist
in a curious way.

If alcohol and water are mixed, the particles suspended
acquire a rapid motion from the currents set up, which
continues till the fluids are thoroughly blended. Nearly
all substances in a state of minute division exhibit, when
suspended in fluid, a movement called the " Brownonian
motion," from Dr. Robert Brown, who first investigated
it. It is a peculiar, uninterrupted, dancing movement, the
cause of which is still unexplained. These movements,
as all others, appear more energetic when greatly magni-
fied by strong objectives. It requires care to discriminate

54 THE MICROSCOPIST.

between such motions and the vital or voluntary motions
of organized bodies.

The inflection or diffraction of light is another source
of error, since the sharpness of outline in an object is thus
impaired. The shadow of an opaque object in a divergent
pencil of light presents, not sharp, well-defined edges, but
a gradual shading off, from which it is inferred that the
rays do not pass from the edge of the object in the same
line as they come to it. This is in consequence of the
undulatory nature of light. When any system of waves
meets with an obstacle, subsidiary systems of waves will
be formed round the edge of the obstacle and be propagated
simultaneously with the original undulations. For a cer-
tain space around the lines in which the rays, grazing the
edge of the opaque body, would have proceeded, the two
systems of undulation will intersect and produce the phe-
nomena of interference. If the opaque body be very small,
and the distance from the luminous point proportionally
large, the two pencils formed by inflection will intersect,
and all the phenomena of interference will become evident.
Thus, if the light be homogeneous, a bright line of light
will be formed under the centre of the opaque object, out-
side of which will be dark lines, and then bright and dark
lines alternately. If the light be compound solar light, a
series of colored fringes will be formed. In addition to
the results of inflection, oblique illumination at certain
angles produces a double image, or a kind of overlying
shadow, sometimes called the "diffraction spectrum,"
although due to a different cause. No rules can be given
for avoiding errors from these optical appearances, but
practice will enable one to overcome them, as it were,
instinctively.

Testing the Microscope. — The defining power of an in-
strument depends on the correction of its spherical and
chromatic aberrations, and excellence may often be ob-
tained with objectives having but a moderate angle of

USB OF THE MICROSCOPE. 55

aperture. It may be known by the sharp outline given
to the image of an object, which is not much impaired by
the use of stronger eye pieces.

Resolving power is the capability an instrument has of
bringing out the fine details of a structure, and depends
mainly on the angle of aperture of the objective, or the
angle formed by the focus and the extremities of the
diameter of the lens. On this account the increase of the
angle of aperture has been a chief aim with practical
opticians.

Penetrating power is the degree of distinctness with
which the parts of an object lying a little out of focus
may be seen. Objectives which have a large angle of
aperture, and in consequence great resolving power, are
often defective in penetration, their very perfection only
permitting accurate vision of what is actually in focus.
Hence for general purposes a moderate degree of angular
aperture is desirable.

Flatness of field of view is also a necessity for accurate
observation. Many inferior microscopes hide their im-
perfection in this respect by a contracted aperture in the
eye-piece, by which, of course, only a part of the rays
transmitted by the objective are available.

Object-glasses whose focal length is greater than half
an inch are called low powers. Medium powers range
from one-half to one-fifth of an inch focal length, and all
objectives less than one-fifth are considered high powers.

For definition with low power objectives, the pollen
grains of hollyhock, or the tongue of a fly, or a specimen
of injected animal tissue, will be a sufficient test. The
aperture should be enough to give a bright image, and
the definition sufficient for a clear image. A section of
wood, or of an echinus spine, will test the flatness of the
field.

Medium powers are seldom used with opaque objects
unless they are very small, but are most useful* with

56 THE MICROSCOPIST.

properly prepared transparent objects. A good half-inch
objective should show the transverse markings between
the longitudinal ribs on the scales of the Hipparchia
janira, butterfly (Plate I, Fig. 27), and the one-fourth or
one-fifth should exhibit markings like exclamation points
on the smaller scales of Podura plumbea (Plate I, Fig. 28)
or Ijepidocyrtis.

High power objectives are chiefly used for the most
delicate and refined investigations of structure, and are
not so suitable for general work. It is with these glasses
that angular aperture is so necessary to bring out striae,
and dots, and other delicate structures, under oblique
illumination. For these glasses, the best tests are the
siliceous envelopes of diatoms, as the Pleurosigma angu-
latum, Surirella gemma, G-rammataphora subtilissima ; or
the wonderful plates of glass artificially ruled by M. Ro-
bert, and known as Nobert's test.

The latter test is a series of lines in bands, the distance
between the lines decreasing in each band, until their
existence becomes a matter of faith rather than of sight,
since no glass has ever revealed the most difficult of them.
The test plate has nineteen bands, and their lines are
ruled at the following distances: Band 1, y^^th of a
Paris line (to an English inch as .088 to 1.000, or as 11 to
125). Band 2, T^O^- Band 3, s^th. Band 5,
Band 9, I0'^th. Band 13, ^th. Band 17,
Band 19, TI,i^th.

It is said that Hartnack's immersion system ~No. 10
and oblique light has resolved the lines in the 15th band,
in which the distance of lines is about ^T J^th of an inch.

The surface markings of minute diatoms are also ex-
cessively fine. Those of Pleurosigma formosum. being from
20 to 32 in y^^th of an inch ; of P. hippocampus and P.
attenuatum about 40 ; P. angulatum 46 to 52 ; Navicula
rhomboides 60 to 111 ; and Amphipleura pelludda 120 to
130. * This latter has been variously estimated at 100,000

PLATE I.

FIG. 28.

FIG. 27.

Scale of Hipparchia Janira.

Scales of Fodura plumbea :— A, large
strongly marked scale; B, small scale
more faintly marked; c, portion of an
injured scale, showing the nature of the
markings.

FIG. 29.

,

* 0 • » I

•**.•

Pleuroxigma angtilntum :— A, entire frustule, as seen
under a power of 500 diam.; B, hexagonal aerolation,
as seen under a power of 1300 diam.; c, the same,
as seen under a power of 15,000 diam.

USE OF THE MICROSCOPE.

57

to 130,000 in an inch. It has been resolved by Dr. Wood-
ward with the y'gth immersion of Powell and Lealand,
using oblique sunlight through a solution of airnnonio-
sulphate of copper.

The longitudinal lines (between the transverse) of the

FIG. 30.

Valve of Surirella Gemma.
a. Transverse ridges. 6. Longitudinal lines, c. The same, resolved into areolations.

Surirella gemma are estimated at 30 to 32 in T^o^n °f a
millimetre, and the markings on Grammataphora subtilis-
sima Sit 32 to 34 in the same distance.

FIG. 31.
a.

Grammataphora Subtilissima.
a. Valve. 6. Transverse lines.

J. D. Moller has produced a very excellent test-plate,
containing twenty diatoms, with descriptions, according
to their value as tests.

58 THE MICROSCOPIST.

The Pleurosigma angulatum (Plate I, Fig. 29), with suit-
able power and illumination, should show distinct hexag-
onal areolations. The Surirella gemma (Fig. 30) shows a
series of fine transverse lines across the ridges which run
from the edge to the central line. The finest of these
ridges are not always readily seen, and the transverse
ones are only to he mastered by toil and patience.

The Grammatapliora subtilissima (Fig. 31) shows trans-
verse lines (or rows of dots) along the edge, and sometimes
a double series of oblique lines.

CHAPTER Y.

MODERN METHODS OF EXAMINATION.

MICROSCOPY does not limit its researches to optical
enlargement, but seeks to comprehend elementary struc-
ture, and its methods vary according to the object imme-
diately in view. It may seek merely to discern the form
or morphology of the elementary parts or their peculiar
functions. It may be concerned with inorganic forms,
normal or pathological anatomy, or with physiology.
Each department of pursuit will suggest some variation,
yet a general plan of operation is possible.

Coarse, and moderately large objects, as a small insect,
a piece of vegetable tissue, etc., may be observed by plac-
ing it in the forceps, or on the stage of the instrument,
under an objective of low power, but ordinarily a consid-
erable degree of preparation is needed in order to acquire
a true idea of structure.

Most of the tissues to be examined are in a moist con-

MODERN METHODS OF EXAMINATION. 59

dition, and many require to be dissected or preserved in
fluid. This has much to do with the appearance of the
object in the microscope. If fibres or cells are imbedded
in connective tissue or in fluids, of which the refractive
power is the same as their own, they cannot be perceived
even with the best glasses, and artificial means must be
resorted to that they may become visible. The refractive
power of different media causes different appearances.
Thus a glass rod lying in water is easily seen, but in
Canada balsam, whose refractive power is nearly the same
as glass, it is barely seen as a flat band, and in the more
highly refractive anise oil it. presents the appearance of a
cavity in the oil.

During life the cavities and fissures in animal tissues,
in consequence of the different refractive power of their
contents and the change which takes place soon after
death, exhibit a sharpness and softness of outline which
is seldom seen in preparations.

There are two methods of microscopic investigation or
of preparation preliminary to direct observation: 1. Me-
chanical, for the separation and isolation of the elemen-
tary parts. 2. Chemical, which dissolve the connecting
material, or act on it differently than on other elements.

For minute dissection a great variety of instruments
have been proposed, but by practiced hands more can be
accomplished in shorter time by simple means than with
complicated ones. Two or three scalpels, or small ana-
tomical knives, a pair of small scissors, such as is used in
operations on the eye, and fine-pointed forceps, will be
found useful. But the most serviceable instruments are
dissecting-needles, such as the microscopist may make for
himself. A common sewing-needle, with the eye end
thrust into a cedar stick about three inches long and one-
fourth of an inch diameter, will answer the purpose. The
point should not project so far as to spring, and if desired,
a cutting edge can be given to it by a hone.

60

THE MICROSCOPIST.

The light should be concentrated on the work by means
of a bull's-eye condenser, and as far as possible, the dis-
section should be carried on with the unassisted eye.
Very often the work is so fine that a magnifying glass,
or simple microscope, fixed to a suitable arm, will be
needed. A large Coddington lens, an inch and a half in
diameter, such as is used frequently by miners, will be
useful. Sometimes it is necessary to resort to the dissect-
ing microscope, which is a simple lens, of greater or less
power, arranged with rack and pinion, mirror, etc.

The specimen may be dissected under water, in a glass
or porcelain dish, or a trough made of gutta-percha, etc.
Dr. Lawson's binocular dissecting microscope (Fig. 32) is

FIG. 32.

Lawson's Binocular Dissecting Microscope.

a most useful form, as both eyes may be used. Loaded
corks, with sheet lead fastened to their under surface,
may be used to pin the subject on for greater facility in
dissection. Rests, or inclined planes of wood, one on each
side of the trough, will give steadiness to the hands.
Camels'-hair pencils for the removal of dust and extrane-

MODERN METHODS OP EXAMINATION. 61

ous elements, and for spreading out thin and delicate tis-
sues or sections, are indispensable. Pipettes, or glass
tubes, one end of which can be covered with the end of
the finger, may serve to convey a drop of fluid or a small
specimen from a bottle.

Preparation of Loose Textures. — If the formed elements
of tissue do not combine in a solid mass, it is only neces-
sary to place a small quantity on a glass slide and cover
it with a plate of thin glass. If the elements are too close
for clear definition under the microscope, a drop of fluid
may be added. The nature of this fluid, however, is not
a matter of indifference. Some elements are greatly
changed by water, etc., and it becomes important to con-
sider the fluid which is most indifferent. Glycerin and
water, one part to nine of water, will serve well for most
objects. Animal tissues are often best treated with aque-
ous humor, serum, or iodized serum. A weak solution of
salt, 7.5 grains chloride of sodium to 1000 grains of dis-
tilled water, serves for many delicate structures. (See
section on Fluid Media.)

Preparation by Teasing. — A minute fragment of tissue
should be placed in a drop of fluid on a slide, and torn or
unravelled by two sharp needles. This is accomplished
more easily after maceration, and sometimes it is neces-
sary to macerate in a substance which will dissolve the
connecting material. This picking or teasing should be
slowly and accurately performed. Beginners often fail
of a good preparation by ceasing too soon, as well as by
having too large a specimen. The most delicate manipu-
lation is required to isolate nerve-cells and processes.

Preparation by Section. — A section of soft substance may
be made with a sharp knife or scalpel, or with a pair of
scissors curved on the upper side. A section cut with the
latter will taper away at the edges so as to afford a view
of its structure.

62 THE MICROSCOP1ST.

Valentin's double knife (Fig. 33) is used for soft tissues
where only a moderate degree of thinness is needed. The
blades should be wet, or the section made under water.

Soft substances often require hardening before sections
can be made The most simple and best method is that
of freezing, by surrounding the specimen with a freezing
mixture, when it may be cut with a cold knife. Small
pieces of tissue may be hardened in absolute alcohol, fre-
quently renewed. Chromic acid, in solution of one-fourth
to two per cent., is often used for animal tissues, or bichro-
mate of potash of the same strength. A solution of one-
fifth to one-tenth per cent, of perosmic acid or of chloride
of palladium is also recommended.

Soft tissues often require imbedding in a concentrated
solution of gum or of wax, spermaceti, or paraffin tem-
pered with oil. In this case sections may be made readily
by means of a section-cutter. For imbedding in wax, etc.,

FIG. 33.

Valentin's Knife.

the specimen must be hardened in alcohol, then treated
with oil of cloves or turpentine, and the section should be
mounted in Canada balsam or Dammar varnish.

Sections of hard substances, or of those imbedded, are
often made by machines invented for the purpose. One
of the simplest is (Fig. 34) an upright hollow cylinder,
with a kind of piston, pushed upwards by a fine screw.
The upper end of the cylinder carrying the specimen ter-
minates in a flat table, along which a sharp knife or flat
razor is made to slide. At one side of the tube is a
binding-screw for holding the specimen steady. A sec-

MODERN METHODS OF EXAMINATION. 63

tion may be cut by such an instrument after inserting
the structure desired in a piece of carrot, etc., which may
be placed in the tube ; or the tube may be filled with wax,
etc., and the specimen imbedded. Bones, teeth, shells,
corals, minerals, etc., require to be cut with fine saws, or
a disk of thin iron on a lapidary's wheel, and filed or
ground down to the requisite thinness, then polished with
emery, rouge, etc. The green oxide of chromium has
been suggested to me as a useful polishing powder for
hard substances. For calcareous substances, files and
hones will suffice to reduce the thickness, and putty

FIG. 34.

Section-Cutter.

powder or jewellers' rouge for polishing. They should
be mounted in Canada balsam.

Staining Tissues. — Certain elements, not previously visi-
ble, can often be made evident by certain coloring matters,
by wrhich some constituents become more quickly or more
thoroughly stained than others. The " germinal matter,"
or "bioplasm" of Dr. Beale, identical with the "proto-
plasm " or " sarcode " of other observers, may thus be dis-
tinguished from the " formed materials " or " tissue ele-

64

THE MICROSCOPIST.

ment," which are the products of its activity. Carmine,
auilin, haematoxylin, and picric acid, are used for staining
by imparting their own color to tissues ; while nitrate of
silver, chloride of gold, chloride of palladium, and peros-
mic acid stain, by their chemical action, often under the
reducing influence of light. (See Fluid Media.}

Injecting Tissues. — Injections of the vessels in animal
tissues are resorted to either to exhibit their course or the
structure of the vascular walls. For the latter purpose a
solution of nitrate of silver is commonly employed, for the
former either opaque or transparent coloring matter. (See
Fluid Media.}

The injecting syringe (Fig. 35) is made of brass or Ger-

FlG. 35.

Injecting Syringe.

man silver. One of the pipes should be inserted into the
principal vessel, as the aorta of a small animal, the um-
bilical vein of a fetus, or the artery, etc , of an organ,
and should be securely fastened by a thread. All other
open vessels should be tied. The solution of gelatin, or
other matter used, should be strained, so as to be free
from foreign particles, and should be forced into the ves-
sels with a gentle, steady pressure on the syringe.

Injections should be made soon after the death of the
animal, or else after the rigor mortis has subsided.

MODERN METHODS OF EXAMINATION. 65

Sometimes the syringe is substituted by a self-acting
apparatus, consisting of a Wolfe's bottle, containing the
fluid, which is pressed upon by a column of air from
another source, and driven through a flexible tube to the
pipe in the bloodvessel.

The older anatomists used colored plaster or wax to
demonstrate the arteries and veins, but modern histology
requires finer materials. Isinglass or gelatin, colored, and
injected warm, or a solution of colored glycerin, are now
resorted to. The former serves for opaque, and the latter
for fine, transparent injections.

The art of injecting can only be learned by practice,
yet perseverance, in despite of many failures, will insure
success.

The liver, kidney, etc., may be injected separately, and
it is often desirable to use various colors for the different
sets of vessels. After injection thin slices may be cut off
and mounted in fluid or balsam.

Preparation in Viscid Media. — Dr. Beale has proposed a
method of preparing animal and vegetable tissues for ex-
amination with the very highest powers, which has led to
valuable results. It consists in using pure glycerin or
strong syrup, instead of watery solutions. In this way
an amount of, pressure may be applied to sections, in order
to render them thin enough for examination, which would
be destructive to specimens in water, while the preserva-
tive action of the media prevents change in the structure.
It is necessary to soak the specimen some time, and the
strength of the fluid should be gradually increased until
the tissue is permeated by the strongest that can be ob-
tained. Dr. Beale has found that minute dissection is
much more readily performed in such fluids, and that
even very hard textures, as bone and teeth, may be softened
by them, especially if acetic acid is added, so as to permit
thin sections to be made with a knife. He recommends

5

66 THE MICROSCOPIST.

vessels to be first injected, as with fine, transparent blue,
and the germinal matter to be stained with carmine. A
few drops of a solution of chromic acid, or bichromate of
potash, so as to impart to the glycerin a pale straw color,
serves to harden even the finest nerve-structures. Acetic
acid, and other reagents also, are much more satisfactorily
used with glycerin than with water. If syrup is used,
camphor, carbolic acid, etc , must be employed to prevent
the growth of fungi, but pure glycerin is free from this
inconvenience.

A great advantage of this mode of investigation con-
sists in the fact that a specimen thus prepared is already
mounted, and needs but a proper cement to the glass cover
and a finish to the slide, when it is ready for the cabinet.

FLUID MEDIA.
1. INDIFFERENT FLUIDS.

The vitreous hnmor, amniotic liquor, serum, etc., which
form the usual fluids termed indifferent, always contain
what Prof. Graham designated colloid and crystalloid
substances. In 1 000 parts there are about 4 parts of col-
loid (albumen) and 7.5 of crystalloid substance (chloride
of sodium).

The iodine serum of Schultze consists of the amniotic
fluid of the embryo of a ruminant, to which about 6 drops
of tincture of iodine to the ounce is added A small piece
of camphor will preserve this from decomposition a long
time. A substitute for this is composed of 1 ounce of
white of egg, 9 ounces of water, 2 scruples chloride of
sodium, with the corresponding quantity of tincture of
iodine.

MODERN METHODS OF EXAMINATION. 61

2. CHEMICAL REAGENTS.

The greatest care should be used with these, that the-
instruraent and glasses may be preserved. A small drop,,
applied by a glass rod drawn out to a point to the edge of
the glass cover, will suffice in most cases.

Sulphuric Add. — Concentrated is used to isolate the-
cells of horny structures, as hair, nails, etc. Dilute (1 part
to 2-3 of water) gives to cellulose, previously dyed with,
iodine, a blue or purple color, and, when mixed with
sugar, a rose-red to nitrogenous substances and bile. 0.1
to 1000 of water, at a temperature of 35-40° C., resolves
connective tissue into gelatin and dissolves it, so as to be
useful in isolating muscular fibres.

Nitric Acid. — Diluted with 4 or 5 parts water, separates
the elementary parts of many vegetable and animal tis-
sues when they are boiled or macerated in it. With chlo-
rate of potash it is still more energetic, but caution is
needed in its use.

Muriatic Acid, Strong. — Used for dissolving intercellular
substance, as in the tubes of the kidney, etc. Dilute for
dissolving calcareous matter.

Chromic acid, J to 2 per cent, solution for hardening
nerves, brain, etc.

Oxalic acid, to 15 parts water, causes connective tissue
to swell and become transparent, while albuminoid ele-
ments are hardened. Preserves well delicate substances,
as rods of retina, etc.

Acetic acid makes nuclei visible and connective tissue
transparent, so as to exhibit muscles, nerves, etc., other-
wise invisible.

Iodine (\ grain of iodine, 3 grains iodide of potassium,
1 ounce of water) turns starch blue and cellulose brown.

Caustic potash or soda renders many structures trans-
parent.

68 THE MICROSCOPIST.

Lime-water or baryta-water is used for investigating con-
nective structures, especially tendon, as maceration en-
ables the needle to divide its fibril! a.

Chloride of Sodium. — Solutions of this salt for indifferent
media should always have some colloid, as albumen or
gum-arabic added (7.5 grains in 1000 grains of water for
delicate structures).

JBicfoomate of potash is used in stronger solution for the
same purposes as chromic acid.

Mutter's eye-fluid for hardening the retina, and preserv-
ing delicate embryos, etc., consists of bichromate of potass.,
2 grammes ; sulphate of soda, 1 gramme ; distilled water,
100 grammes.

Alcohol dissolves resins and many vegetable coloring
matters ; renders most vegetable preparations more trans-
parent, and albuminous animal tissues more opaque.

Acetic acid and alcohol, 1 part of each to 2 of water,
renders connective tissue transparent, and albuminoid tis-
sue prominent. The proportions can be varied.

Alcohol and soda (8-10 drops of strong solution of caustic
soda to each ounce) renders many tissues very hard and
transparent. Beale recommends it for embryonic struc-
tures.

Ether dissolves resins, oils, and fat.

Turpentine renders dried animal sections transparent.

Oil of cloves acts as turpentine.

Solution of chloride of zinc, iodine, and iodide of potassium,
is recommended by Schacht as a substitute for iodine and
sulphuric acid to color vegetable cells, etc. Zinc is dis-
solved in hydrochloric acid, and the solution is evaporated
to syrupy consistence in contact with metallic zinc. This
is saturated with iodide of potassium, iodine added, and
the solution diluted with water. Wood cells, after boiling
in caustic potash, are stained blue by it.

Boracic acid, used by Prof. Brucke to separate the ele-
ments of red blood-corpuscles.

MODERN METHODS OF EXAMINATION. 69

3. STAINING FLUIDS.

Thier setts Carmine Fluids.
a. RED FLUID.

1. Carmine, 1 part.

Caustic ammonia, . . . . . 1 "

Distilled water, 3 parts. Filter.

2. Oxalic acid, 1 part.

Distilled water, 22 parts.

1 part of carmine solution to 8 parts of the acid solution, add 12 parts
absolute alcohol. Filter. After staining wash in 80 per cent, alcohol.

b. LILAC FLUID.

Borax, . . ..: • • • • 4 parts.

Distilled water, 56 "

Dissolve and add,

Carmine, . . . . . . .1 part.

Mix with twice the volume of absolute alcohol and filter.

Beetle's Carmine Fluids.

Carmine, ....... 10 grains.

Strong liquor ammonia, £ drachm.

Glycerin, ....... 2 ounces.

Distilled water, . . . . 2 "

Alcohol, £ ounce.

Dissolve the carmine in the ammonia in a test-tube by aid of heat ; boil
it and cool and add the other ingredients. Filter.

Acid Carmine Fluid. — Mix ammoniacal solution of car-
mine with acetic acid in excess and filter. This is said
to stain diffusely, but adding glycerin with muriatic acid
(1 : 200), concentrates the color in the cell-nucleus.

Anilin (or Magenta] Red Fluid.

Fuchsin (crystal), 1 centigramme.

Absolute alcohol, .... 20-25 drops.
Distilled water, ..... 15 cubic centim.

Anilin Blue Fluid. — Anilin blue, treated with sulphuric
acid and dissolved in water till a deep cobalt color is
obtained.

70 THE MICROSCOPIST.

Blue Fluid from Indigo Carmine.

Oxalic acid, ....... 1 part.

Distilled water, . . . . . 20-30 parts.

Indigo carmine to saturation.

Logwood Violet Fluid.

1. Ha3matoxylin, . . . . .20 grains.
Absolute alcohol, . . . . . £ ounce.

2. Solution of 2 grains of alum to 1 ounce of water.

A few drops of the first solution to a little of the second in a watch-
glass, etc.

Picro-Carmine Fluid. — Filter a saturated solution of
picric acid, and add, drop by drop, strong ammoniacal
solution of carmine till neutralized.

Nitrate of Silver Fluid. — Fresh membranous tissues,
exposed to 0.5 to 0.2 per cent, solution of nitrate of silver,
washed and exposed to light, often show a mosaic of epi-
thelium, etc.

Osmie Acid. — y^th to 1 per cent, solution stains the
medulla of nerves, etc., black.

Chloride of Gold. — The solution should be similar to that
of nitrate of silver. Exposure to light stains the nerves,
etc., a violet or red color.

Prussian Blue. — After immersing a tissue in 0.5 to 1
per cent, solution of a protosalt of iron, dip it in a 1 per
cent, solution of ferrocyanide of potassium.

Other Staining Fluids. — Marked effects are often pro-
duced by the use of the violet, blue, and other inks in the
market. Thus I succeeded in some demonstrations of
nerve plexuses in muscle better than in any other way.
I suspect the particular ink employed contained a large
per cent, of soluble Prussian blue.

4. INJECTING FLUIDS.

For opaque injection several plans have been devised.
Eesinous and gelatinous substances, variously colored, are

MODERN METHODS OF EXAMINATION. 71

most usual. Lieberkuhn used tallow, varnish, and tur-
pentine, colored with cinnabar ; and Hyrtl, whose prepa-
rations have been much admired, follows a similar plan.
He evaporates pure copal or mastic varnish to the consis-
tence of syrup, and grinds one-eighth as much cinnabar
and a little wax with it on a slab. For fine injections this
is diluted with ether.

For a bright red, the cinnabar may be mixed with a
little carmine

For a yellow color, the chromate of lead, prepared by
mixing solutions of acetate of lead (36 parts to 2 ounces
of water), and red chromate of potash (15 parts).

White may be made with zinc-white or carbonate of
lead — 4J ounces of acetate of lead in 16 ounces of water,
mixed with 3 J ounces carbonate of soda in 16 ounces.

For gelatinous injections the coloring matter is com-
bined with jelly, prepared by soaking fine gelatin in cold-
water for several hours, then dissolving in a water-bath
and filtering through flannel.

By injecting gelatinous fluid solutions of various salts,
the coloring matter may be left in the vessels by double
decomposition.

A red precipitate, with iodide of potassium and bichlo-
ride of mercury.

A blue, by ferrocyanide of potassium and peroxide of
iron, etc.

Dr. Goadby's formula for a yellow color is :

Saturated solution of bichromate of potassium, . 8 ounces.
Water, . . . ... . .';* . 8 "

Gelatin, . ,| .. ,.«., 2 "

Saturated solution of acetate of lead, . . .8 ounces.

Water, . .' ff 8 "

Gelatin, .... . . . . ; . 2 "

For gelatinous injections, both the fluid and the subject
should be as warm as may consist with convenience.
Camphor also should be added to prevent mould.

72 THE MICROSCOPIST.

For transparent injections, gelatin may be used combined
with colored solutions, or still better, glycerin, which may
be used cold.

Thiersch's Blue. — Half an ounce of warm concentrated
solution (2: 1) of fine gelatin is mixed with 6 cubic centim-
etres of a saturated solution of sulphate of iron. In
another vessel, 1 ounce of the gelatin solution is mixed
with 12 cubic centimetres of saturated solution of ferro-
cyanide of potassium, to which 12 cubic centimetres of
saturated solution of oxalic acid is added. When cold,
add the gelatinous solution of sulphate of iron drop by
drop, with constant stirring, to the other. Warm it,
still stirring, and filter through flannel.

Gerlach's Carmine. — Dissolve 5 grammes (77 grains) of
fine carmine in 4 grammes (70 grains) of water and J
gramme (8 drops) of liquor ammonia. Let it stand sev-
eral days (not airtight), and mix with a solution of 6
grammes of fine gelatin to 8 grammes of water, to which
a few drops of acetic acid are added.

Thiersch's Yellow. — Prepare a solution of chromate of
potash (1 : 11), and a second solution of nitrate of lead, of
same strength. To 1 part of the first add 4 parts of solu-
tion of gelatin (about 20 cubic centimetres to 80), and to
2 parts of the second add 4 parts of gelatin (40 cubic cen-
timetres to 80). Mix slowly and carefully, heat on a
water-bath, and filter through flannel.

Equal parts of Thiersch's blue and yellow carefully
mixed and filtered make a good green.

COLD TRANSPARENT INJECTIONS.

Beale's Blue.

Glycerin,. . . > . . 1 ounce.

Alcohol, . ., 1 "

Ferrocyanide of potassium, .... 12 grains.
Tincture of perchloride of iron, . . . 1 drachm.

Water, 4 ounces.

MODERN METHODS OF EXAMINATION. 73

Dissolve the ferrocyanide in 1 ounce of water and glyc-
erin, and the muriated tincture of iron in another ounce.
Add the latter very gradually to the other, shaking often ;
then gradually add the alcohol and water.

Scale's Finest Blue.

Price's glycerin, ...... 2 ounces.

Tincture of perchloride of iron, . . . 10 drops.
Ferrocj^anide of potassium, .... 3 grains.

Strong hydrochloric acid, ..... 3 drops.

Water, . . . . . . . .1 ounce.

Mix the tincture of iron with 1 ounce glycerin and the
ferrocyanide, after dissolving in a little water, with the
other ounce. Add the iron to the other solution gradu-
ally, shaking well. Lastly, add the water and hydro-
chloric acid. Sometimes about 2 drachms of alcohol are
added.

Mutter's Blue. — This is made by precipitation of soluble
Prussian blue from a concentrated solution by means of
90 per cent, alcohol.

Beale's Carmine. — Mix 5 grains of carmine with a few
drops of water, and when well incorporated, add 5 or 6
drops of liquor ammonia. To this add J ounce of glyc-
erin, and shake well. Another J ounce of glycerin con-
taining 8 or 10 drops of acetic or hydrochloric acid is
gradually added. It is then diluted with J ounce of glyc-
erin, 2 drachms of alcohol, and 6 drachms of water.

Nitrate of Silver Injection. — For demonstrating the struc-
ture of the bloodvessels, the animal is bled, and a solution
of 0.25 to 1 per cent, of nitrate of silver, or a mixture of
gelatin with such a solution, is used.

5. PRESERVATIVE FLUIDS.

Canada Balsam. — This is perhaps the most common
medium used. When an object is not very transparent,
and drying will not injure it, balsam will do very well,

74 THE MICROSCOPIST.

but it is not adapted to moist preparations. Colonel
Woodward, of Washington, uses a solution of dried or
evaporated Canada balsam in chloroform or benzole.

Dammar Varnish. — Dr. Klein and other German his-
tologists prefers this to Canada balsam. Dissolve J to 1
ounce of gum Dammar in 1 ounce of turpentine ; also }
to 1 ounce of mastic in 2 ounces of chloroform. Mix and
filter.

Glycerin. — This fluid is universally useful to the micros-
copist. (See Preparation in Viscid Media, page 65.) Vege-
table and animal substances may be preserved in glycerin,
but if it is diluted, camphor or creasote must be added
to prevent confervoid growths. It is said, however, to
dissolve carbonate of lime.

Gelatin and Glycerin. — Soak gelatin in cold water till
soft, then melt in warm water, and add an equal quantity
of glycerin.

Gum and Glycerin. — Dissolve 1J grains of arsenious
acid in 1 ounce of water, then 1 ounce of pure gum arabic
(without heat), and add 1 ounce of glycerin.

Deane's Compound. — Soak 1 ounce of gelatin in 5 ounces
of water till soft ; add 5 ounces of honey at a boiling heat.
Boil the mixture, and when cool, add ti drops of creasote
in | ounce of alcohol; filter through flannel. To be used
warm.

Carbolic Acid. — 1 : 100 of water is a good preservative.

Thwaite's Fluid.— To 16 parts of distilled water, add 1
part of rectified spirit and a few drops of creasote ; stir in
a little prepared chalk, and filter. Mix an equal measure
of camphor-water, and strain before using. For preserva-
tion of algse.

Solution of Naphtha and Creasote. — Mix 3 drachms of
creasote with 6 ounces of wood naphtha ; make a thick,
smooth paste with prepared chalk, and add gradually,
rubbing in a mortar, 64 ounces of water. Add a few
lumps of camphor, and let it stand several weeks before

MODERN METHODS OP EXAMINATION. 75

pouring off or filtering the clear fluid. Dr. Beale recom-
mends this highly for the preservation of dissections of
nerves and morbid specimens.

Ealfs Fluid.— As a substitute for Thwaite's fluid in
the preservation of algae. 1 grain of alum and 1 of bay
salt to 1 ounce of distilled water.

Goadby's Solution. — Bay salt, 4 ounces; alum, 2 ounces;
corrosive sublimate, 4 grains ; boiling water, 4 pints.
This is the strength most generally useful, although it
may be made stronger or more dilute. It is a useful
fluid. If the specimen contain carbonate of lime, the
alum must be left out, and the quantity of salt may be
quadrupled.

Dr. Beale discards all solutions containing salts for
microscopic purposes, as they render the textures opaque
and granular.

Soluble Glass, or a solution of silicate of soda or potash,
or of both, has been proposed, but it is apt to render
specimens opaque.

Chloride of Calcium in saturated aqueous solution has
been much recommended, especially by botanists.

Acetate of Potash, a nearly saturated solution, is useful
for vegetable preparations and for specimens of animal
tissue which have been stained with osmic acid. The
latter do not bear glycerin.

Pacinian Fluid.— This is variously modified, but may
consist of corrosive sublimate, 1 part ; chloride of sodium,
2 parts; glycerin, 13 parts; distilled water, 113 parts.
Sometimes acetic acid is substituted for chloride of so-
dium.

6. CEMENTS.

Gold Size is recommended by Dr. Carpenter as most
generally useful for thin covers. It is made by boiling
25 parts of linseed oil for three hours with 1 part of red
lead and J of as much umber. The fluid part is then
mixed with yellow ochre and white lead in equal parts,

76 THE MICROSCOPIST.

so as to thicken it, the whole boiled again, and the fluid
poured off for use.

Bell's Cement is said to be best for glycerin specimens.
It appears to be shellac dissolved in strong alcohol.

Brunswick Black is asphaltum dissolved in turpentine.
A little india-rubber dissolved in mineral naphtha is some-
times added.

Canada Balsam in chloroform or Dammar varnish (page
74) is often used as a cement.

Marine Glue. — This is most useful in building glass
cells, etc. It consists of equal parts of shellac and india-
rubber dissolved in mineral naphtha by means of heat.

Electrical Cement is made by melting together 5 parts
of rosin, 1 of beeswax, and 1 of red ochre. 2 parts of
Canada balsam added make it more adhesive to glass.

White, hard Varnish, or gum sandarac, dissolved in
alcohol and mixed with turpentine varnish, is sometimes
colored by lampblack, sealing-wax, etc.

White Zinc Cement. — Oxide of zinc rubbed up with
equal parts of oil of turpentine and 8 parts of solution of
gum Dammar in turpentine of a syrupy consistence, or
Canada balsam, chloroform, and oxide of zinc.

CHAPTER VI.

MOUNTING AND PRESERVING OBJECTS FOR THE MICROSCOPE.

FOR the permanent preservation of specimens, various
means are employed, according to the nature of the object
and the particular line of investigation desired. Few, if
any, objects show all their peculiarities of structure or
adaptation to function, and for scientific work it is often

MOUNTING AND PRESERVING OBJECTS. 77

necessary to have the same structure prepared in different
ways.

Opaque Objects have sometimes been attached by thick
gum to small disks of paper, etc , or to the bottom and
sides of small pill-boxes, or in cavities in slides of bone or
wood, but they are better preserved on glass slides, as
hereafter described.

The most convenient form of slide for microscopic pur-
poses is made of flattened crown or flint glass, cut into
slips of three inches by one inch, and ground at the edges.
Some preparations are mounted on smaller slips, but they
are less convenient than the above, which is regarded as
the standard size.

On such slides objects are fixed, and covered by a square
or round piece of thin glass, varying from g^th to 2J5th
of an inch in thickness. Both slides and thin glass can
be procured at opticians' stores. Laminae of mica or talc
are sometimes used for lack of better material, but are too
soft. For object-glasses of the shortest focal length, how-
ever, it is necessary at times to resort to this sort of cov-
ering.

Great care should be taken to have both slide and cover
clean. With thin glass this is difficult, owing to its brit-
tleness. Practice will teach much, but for the thinnest
glass two flat pieces of wood covered with chamois leather,
between which the cover may lie flat as it is rubbed; will
be serviceable.

Very thin specimens may be mounted in balsam, glyc-
erin, etc., covered with the thin glass cover, and then
secured by a careful application of cement to the edges of
the cover. If, however, the pressure of the thin glass be
objectionable, or the object be of moderate thickness, some
sort of cell should be constructed on the slide.

The thinnest cells are made with cement, as gold size,
Brunswick black^ etc., painted on with a camel's-hair pen-
cil. For preparing these with elegance, Shadbolt's turn-

78

THE MICROSCOPIST.

table has been contrived (Fig. 36). The slide is placed
between the springs, and while rotated, a ring of varnish
of suitable breadth is made on the glass.

A piece of thin glass (or even of thick glass) may be
perforated and cemented to the slide with marine glue by

FIG.

Shadbolt's Turntable for making Cement-Cells.

the aid of heat; or vulcanite, lead, tin, gutta percha, etc.,
may be made into a cell in a similar way as seen in Fig.
37.

The perforation of thin glass may be easily performed
by cementing it over a hole in a brass plate, etc., with
marine glue, and punching it through with the end of a

FIG. 37.

Cell of Glass, Vulcanite, etc.

file. The edges may then be filed to the size of the hole,
and the glass removed by heating the brass. Thicker
glass may be bored with a file by moistening it with
turpentine.

Dry objects, especially if they are transparent, as dia-
toms, thin sections of bone, crystals, etc., may be attached
to the slide with Canada balsam, etc., covered with thin

MOUNTING AND PRESERVING OBJECTS. 79

glass, which should be cemented at the edges, and gummed
over all a strip of colored or lithographed paper, in which
an aperture has been made with a punch.

Mounting in Balsam, or Dammar Varnish is suitable for
a very large proportion of objects. It increases the trans-
parency of many structures, tilling up interstices and cavi-
ties, and giving them a smooth, beautiful appearance.
Very delicate tissues, as fine nerves, etc., are rendered in-
visible by it, and require other fluids, as glycerin.

Before mounting in balsam, the object should be thor-
oughly dry, otherwise a milky appearance will result. It
should then be placed in oil of cloves or of turpentine to
remove greasiness and increase the transparency. A clean
slide, warmed over a spirit-lamp or on a hot plate, should
then have a little balsam placed on its centre, and the
object carefully lifted from the turpentine is put into the
balsam and covered with another drop. The slide should
then be gently warmed, and any air-bubbles pricked with
a needle-point or drawn aside. The thin glass cover should
be warmed and put on gently, in such a way as to lean
first on one edge and fall gradually to a horizontal posi-
tion. The slide may be warmed again, and the superflu-
ous balsam pressed from under the cover by the pressure
of a clean point upon it.

If the object is full of large air-spaces and is not likely
to be injured by heat, the air may be expelled by gently
boiling it in the balsam on the slide. If the object be one
which will curl up, or is otherwise injured by heat, the
air-pump must be resorted to. A cheap substitute for the
air-pump may be made by fitting a piston into a tolerably
wide glass tube closed at one end. The piston should
have a valve opening outwards. The preparation in bal-
sam may be placed at the bottom of the tube, and a few
strokes of the piston will exhaust the air.

To fill a deep cell with Canada balsam, it may be well
to fill it first with turpentine and place the specimen in

80 THE MICROSCOPIST.

it. Then pour in the balsam at one end, the slide being
inclined so that the turpentine may run out at the other.
Lay the cover on one edge of the cell and gradually lower
it till it lies flat. In this way air may be excluded.

The solution of balsam in chloroform needs no heat,
and has little liability of air-bubbles.

The excess of balsam round the edge of the glass cover
may be removed with a knife and cleaned with turpentine
or benzine, etc.

For animal tissues, the oil of cloves is sometimes used
instead of turpentine to increase the transparency, and a
wet preparation, as a stained or injected specimen, may
be mounted in balsam or Dammar by first placing it in
absolute alcohol to extract the water, then transferring
to oil of cloves or turpentine, and lastly, to the balsam.
In a reverse order, a specimen from balsam may be cleaned
and mounted in fluid.

Mounting in Fluid is necessary for the preservation of
the most delicate tissues and such as may be injured by

FIG. 38.

Spring Clip.

drying. Glycerin is perhaps the most generally useful
fluid. (See Preservative Fluids, page 73.)

For mounting in fluid, it is safer to have a thin cell of
varnish prepared first than to risk the running in of the
cement under the cover, as will be likely to occur other-
wise.

The air-pump is sometimes needed in mounting in fluid
to get rid of air-bubbles. A spring clip (Fig. 38) is also

MOUNTING AND PRESERVING OBJECTS. 81

a useful instrument for making moderate pressure on the
glass cover until the cement on its edge is dry. A drop-
ping-tube with a bulbous funnel, covered with thin india-
rubber, for taking up and dropping small quantities of
fluid, wrill also be of service.

Superfluous fluid may be removed from the edge of the
cover by a piece of blotting-paper, care being used not to
draw away the fluid beneath the cover.

As soon as objects are mounted, the slides should be
labelled before cementing is finished, otherwise time will
be lost in searching for a particular object among others,
or the name may be forgotten.

Boxes of wood or of pasteboard, with grooved racks at
the sides, are occasionally used for preserving a collection
of specimens. It is better, however, to have a cabinet
with drawers or trays so that the specimens may lie flat,
with their ends towards the front of the drawer. A piece
of porcelain on the end of the drawer is convenient for
the name of the class of objects contained, to be written
on with lead-pencil.

Collecting Objects. — The methods pursued by naturalists
generally will suffice for a large proportion of the objects
which are matters of microscopic inquiry, but there are
others wrhich, from their minuteness, require special search.
Many fresh-water species of microscopic organisms inhabit
pools, ditches, and streams. Some attach themselves to
the stems and leaves of aquatic plants, or to floating and
decaying sticks, etc. Others live in the muddy sediment
at the bottom of the water. A pond stick has been con-
trived for the collection of such organisms, consisting of
two lengths, sliding one within the other, so that it may
be used as a walking-cane. In a screw socket at one end
may be placed a curved knife for cutting portions of plants
which contain microscopic parasites; or a screw collar for
carrying a screw-topped bottle, which serves to bring up
a sample of liquid ; or it may have a ring for a muslin net.

82 THE MICROSCOPIST.

The net should be confined by an india-rubber band in a
groove, so as to be slipped off readily and emptied into a
bottle. The collector should have enough bottles to keep
organisms from each locality separate, and when animal-
cules are secured enough, air should be left to insure their
safety.

Marine organisms may be obtained in a similar way if
they inhabit the neighborhood of the shore, but others
can only be secured by means of the dredge or tow-net.
The latter may be of fine muslin sewn to a wire ring of
twelve inches diameter. It may be fastened with strings
to the stern of a boat, or held by a stick so as to project
from the side. For the more delicate organisms, the boat
should be rowed slowly, so that the net may move gently
through the water. Firmer structures may be obtained
by attaching a wide-mouthed bottle to the end of a net
made conical, and double, so that the inner cone may act
as a valve. The bottle may be kept from sinking by a
piece of cork. Such a net may be fixed to the stern of a
vessel, and drawn up from time to time for examination.

Minute organisms may be examined on the spot by
fishing them out of the bottle with a pipette, or small
glass tube, and placing them on a slide. A Coddington
or other pocket lens will suffice to show which are desir-
able for preservation.

Many of the lower animals and plants may be kept
alive in glass jars for some time. Frogs, etc., may be
kept under wire covers with a large piece of moist sponge.

Aquaria of various sorts may be procured and stocked
at small expense, and will afford a constant source of in-
struction. For fresh-water aquaria the bottom of the jar,
etc , should be covered with rich black earth, made into
a paste, and this should be surmounted with a layer of
fine washed sand. Roots of Valisneria, Anacharis, or
Ckara may then be planted in the earth and the vessel
filled with water. As soon as the water is clear, put a

MOUNTING AND PRESERVING OBJECTS.

few fresh-water molluscs in to keep clown the growth of
confervse, especially such as feed on decayed vegetable
matter, as Planorbis carinatus, Paludina vivipara, or Am-
phibia glutinosa. When bubbles of oxygen gas appear,,
fish, water insects, etc., may be introduced.

Marine aquaria require more skill than those for fresh
water, but for temporary purposes, the plan described by
Mr. Highley, in Dr. Beale's How to Work with the. Micro-
scope, is excellent. He fills a number of German beaker
glasses with fresh sea-water, and places them in a sunny
window. He then drops in each one or two limpet shells-
from which the animals have been removed, and upon
which small plants of Enteromorpha and Ulva are growing.
In a short time the sides of the jars next the light become
coated with spores. He keeps the other sides clean with
a piece of wood or sponge, so as to observe the small
marine animals which may now be placed in the beakers.
In this way a collection will keep healthy for months.
After the sides are covered with spores, the sea-weeds
may be removed, and the jars placed on a table at such a
distance from the window that the light impinges only
on the coated half, taking care that there is sufficient light
to stimulate the spores to throw off bubbles of oxygen
daily.

Prawns, fish, actiniae, etc., may be fed on shreds of beef
which has been pounded and dried, and then macerated
in sea-water for a few minutes. All dead animals, slime,
or effete matter should be removed by wooden forceps,
etc , as soon as noticed.

84 THE MICROSCOPIST.

CHAPTER VII.

THE MICROSCOPE IN MINERALOGY AND GEOLOGY.

MICROSCOPIC examination of minute fossil organisms, as
Diatoms, Foraminifera, spicules of sponge, etc., has long
been a subject of interest. Latterly, however, the micro-
scope has been found to be essential to the study of phys-
ical geology and petrology. How many crude and verbose
theories respecting cosmogony will disappear by this means
of investigation time must reveal, but the animal nature
of the Eozoon Canadense found in the Serpentine Lime-
stone of the Lauren tian formation of Canada, parallel with
the Fundamental Gneiss of Europe, and the discovery by
Mr. Sorby* of minute cavities filled with fluid in quartz
and volcanic rocks, are indications that speculations based
upon a merely external or even chemical examination of
rock structures are immature and inadequate.

The systematic study of microscopic mineralogy and
geology will require a large outlay of time and patience,
and the field is one which is scarcely trodden. The plan
of this work will only permit a brief outline, sufficient to
aid a beginner, and indicating the value and the methods
of minute investigation.

Preparation of Specimens. — Examination of the outer
surface of a mineral specimen, viewed as an opaque body
with a low power and by condensed light, is sometimes
useful. The metals and their alloys, with most of their
combinations with sulphur, etc , admit of no other method.
Occasionally, as in iron and steel, the microscopic structure
is best seen by polishing the surface, and then allowing
the action of very dilute nitric acid. Mr. Forbesf states

* See Beale's How to Work with the Microscope.

f The Microscope in Geology, Popular Science Review, No. 25.

THE MICROSCOPE IN MINERALOGY AND GEOLOGY. 85

that many vitreous specimens (quite transparent) show no
trace of structure until the surface has been carefully acted
on by hydrofluoric acid.

It is generally necessary to have the specimens flat and
smooth, and thin enough to transmit light. Sometimes
fragments may be thin enough to show structure when
mounted in balsam, as in the case of quartz, obsidian, pitch-
stone, etc., but usually thin sections must be ground and
polished.

Chip off a fragment of the rock as flat and thin as pos-
sible, or cut with a lapidary's wheel, or a toothless saw of
sheet-iron with emery. Grind down the specimen on an
iron or pewter plate 'in a lathe until perfectly flat. Then
grind with finer emery on a slab of fine-grained marble or
slate, and finish with water on a fine hone, avoiding all
polishing powders or oil. When. perfectly smooth, cement
the specimen on a square of glass with Canada balsam,
and grind the other side until as thin as necessary, finish
as before, remove it from the glass, and mount on a glass
slide in balsam.

In this way, most silicates, chlorides, fluorides, carbo-
nates, sulphates, borates, many oxides, sulphides, etc., may
be prepared for examination by transmitted light. Very
soft rocks may be soaked in turpentine, then in soft balsam,
and afterwards heated until quite hard. The deep scratches
on hard minerals, like quartz, left by the use of coarse
emery, may be removed by using fine emery paper held
flat on a piece of plate glass, and finally polished with
rouge on parchment. Perhaps oxide of chromium from
its hardness will be found the best polishing material.
Crystals of soluble salts may be ground on emery paper
and polished with rouge. Sometimes much may be learned
by acting on one side only of a specimen with dilute acid.

Examination of Specimens. — The object of microscopic
examination of minerals is to determine not only the nature
of the material of which they are composed, but also, and

86 THE MICROSCOPIST.

chiefly, their structure, whether homogeneous, derived
from the debris of previous rocks, or from the agency of the
organic world. Ordinary mineral ogical characteristics, as
to hardness, specific gravity, color, lustre, form, cleavage,
and fusibility, and above all, chemical composition, may
•suffice to show the material, but the microscope will give
valuable assistance to this end, and is essential to a knowl-
edge of structure.

Crystalline Forms. — The laws of crystallography teach
that each chemical combination corresponds to a distinct
relation of all the angles which can possibly arise from
the primary form, so that the angular inclination of the
facets of a crystal is a question of importance. This can
be ascertained by a microscope having a revolving stage,
properly graduated, or by the use of a goniometer, which
is a thread stretched across the focus of the eye-lens, and
attached to a movable graduated circle and vernier. The
eye piece attached to the polariscope of Hartnack is thus
arranged, so as to act also as a goniometer.

Crystals are assumed to possess certain axes, and the
form is determined by the relation of the plane surface to
these axes. Although the forms of crystals are almost
infinitely varied, they may be classified into seven crystal-
lographic systems.

1. The Regular Cubic or Monometric System (Fig. 39). —
These crystals are symmetrical, about three rectangular
axes. The simplest forms are the cube and octahedron.
Examples, diamond, most metals, chloride of sodium, fluor
spar, alum.

2. The Quadratic or Dimetric System (Fig. 40). — Crystals
symmetrical, about three rectangular axes, but only two
axes of equal length. Examples, sulphate of nickel, tung-
state of lead, and double chloride of potassium and cop-
per.

3. Hexagonal or Rhombohedral System (Fig. 41). — Crys-
tals with four axes ; three equal in length, in one plane,

FIG. 39.

Principal or Vertical Axes. Secondary or Lateral Axes,

FIG. 41.

Principal Axes. Secondary Axes.

FIG. 42.

Principal Axes, Secondary Axes.

FIG. 43.

Principal Axes. Secondary Axes.

FIG. 44.

Principal Axes.

Secondary Axes.

88 THE MICROSCOPIST.

and inclined 60° to each other, and a principal axis at
right angles to the plane of the others. Examples, quartz,
beryl, and calc-spar.

4. RhomJbic or Trimetric System (Fig. 42). — Three rec-
tangular axes, all of different lengths. Examples, sulphate
of potassium, nitrate of potassium, sulphate of barium,
and sulphate of magnesium.

5. Oblique Prismatic or Monodinic (Fig. 43). — Two axes
obliquely inclined, and a third at right angles to the plane
of these two ; all three being unequal. Examples, ferrous
sulphate, sugar, gypsum, and tartaric acid.

6. Diclinic System. — Two axes at right angles, and a
third oblique to the plane of these ; the primary form
being a symmetrical eight sided pyramid.

7. Doubly Oblique Prismatic or Triclinic (Fig. 44). — Three
axes all inclined obliquely and of equal length. Example,
sulphate of copper.

Crystalline structure being inherent in the nature of
the mineral, becomes perceptible by the manner of divi-
sion. A slight blovv on a piece of calc-spar will separate
it into small rhombohedrons or parallelopipeds, or produce
internal fissures along the planes of cleavage, which will
suffice to determine their angles.

Crystals are often found in groups, with various modes
of arrangement. Cubes are sometimes aggregated so as
to form octahedra, and prismatic crystals are often united
together at one extremity. But the most singular groups
are those called hemitropes, because they resemble a crys-
tal cut in two, with one part turned half round and re-
united to the other.

In all the numerous forms, however, we find in the same
species the same angles or inclination of planes, although
the unequal size of the faces may lead to great apparent
irregularity, as in distorted crystals of quartz, where one
face of the pyramid is enlarged at the expense of the rest.

THE MICEOSCOPE IN MINERALOGY AND GEOLOGY. 89

An apparent distortion may also be produced by an oblique
section.

The following examples may be of service, as showing
the value of angular measurement in minerals:

Quartz. Rhombohedral system. Inclination of two
adjoining faces 94° 15'.

Felspar. Monoclinic. Cleavage planes at right angles.

Albite or soda felspar. Triclinic. Angle 93° 36'.

Mica. Oblique prisms.

Magnesian mica. Right, rhombic, or hexagonal prisms.

Garnet. Dodecahedrons or trapezohedrons.

Idocrase. Square prisms.

Epidote. Oblique prisms.

Scapolite. Square and octagonal prisms.

Andalusite. Prisms of 90° 44'.

Staurotide. Rhombic prisms of 129° 20'.

Tourmaline. Three, six, nine, or twelve-sided prisms.

Topaz. Rhombic prisms of 124° 19'.

Beryl. Six-sided prisms.

Hornblende. Monoclinic. 124° 30'.

Augite or pyroxene. Monoclinic. 87° 5'.

Calcite or carbonate of lime. Forms various, but 105°
5' between the cleavage faces.

Magnesite. Angle 107° 29'.

Dolomite. 106° 15'.

Gypsum. Monoclinic.

Crystals within Crystals. — Many specimens which appear
perfectly homogeneous to the naked eye are shown by the
microscope to be very complex. The minerals of erupted
lavas are often full of minute crystals, leading to very
anomalous results of chemical analysis. Some care is
needed at times to distinguish such included minerals
from cavities filled with fluid. The use of polarized light
will sometimes determine this point.

Cavities in Crystals. — Mr. Sorby has shown that the
various cavities in minerals containing air, water, glass,

90 THE MICKOSCOPIST.

or stone will often indicate under what conditions the
rock was formed. Thus crystals with water cavities were
formed from solution ; those with stone or glass cavities
from igneous fusion ; those with both kinds by the com-
bined influence of highly heated water and melted rock
under great pressure ; while those that contain no cavi-
ties were formed very slowly, or from the fusion of homo-
geneous substance.

Use of Polarized Light. — Mr. Sorby states that the
action of crystals on polarized light is due to their double
refraction, which depolarizes the polarized beam, and
gives rise to colors by interference if the crystal be not
too thick in proportion to the intensity of its power of
double refraction. This varies much, according to the
position in which the crystal is cut, yet we may form a
general opinion, since it is the intensity and not the char-
acter of the depolarized light which varies according to
the position of the crystal. There are two axes at right
angles to each other, and when either of them is parallel
to the plane of polarization, the crystal has no depolariz-
ing action, and if the polarizing and analyzing prisms are
crossed, it looks black. On rotating the crystal or the
plane of polarization, the intensity of depolarizing action
increases until the axes are at 45°, and then diminishes
till the other axis is in the plane. If, therefore, this takes
place uniformly over a specimen, we know that it has one
simple crystalline structure, but if it breaks up into de-
tached parts, we know it is made up of a number of sepa-
rate crystalline portions.

The definite order that may occur in the arrangement
of a number of crystals may indicate important differences.
Some round bodies, for example, like oolitic grains, have
been formed by crystals radiating from a common nu-
cleus ; whilst others, as in meteorites, have the structure
of round bodies which crystallized afterwards.

Sir .D. Brewster discovered that many crystals have

THE MICROSCOPE IN MINERALOGY AND GEOLOGY. 91

two axes of double refraction, or rather axes around which
double refraction occurs. Thus nitre crystallizes in six-
sided prisms, with angles of about 120°. It has two axes
of double refraction inclined about 2J° to the axes of the
prism, and 5° to each other, so that a piece cut from such
a crystal perpendicular to the axes, shows a double system
of rings when a ray of polarized light is transmitted.
When the line connecting the axes is inclined 45° to the
plane of polarization, a cross is seen, which gradually
assumes the form of two hyperbolic curves on rotating
the specimen If the analyzer be revolved, the black cross
will be replaced by white, the red rings' by green, the yel-
low by indigo, etc. These rings have the same colors as
thin plates, or a system of rings round one axis. Mica
has two sets of rings, with the angle between the axes of
60° to 75°. Magnesian mica gives an angle of 5° to 20°.
Determination of the Origin of Rock Specimens. — Mr.
Forbes has shown that the primary or eruptive rocks,
consisting chiefly of crystallized silicates, with small
quantities of other minerals, are developed as more or
less perfect crystals at all angles to one another, indicat-
ing the fluid state of the mass at some previous time.
The secondary or sedimentary rocks consist of rocks
formed by the immediate products of the breaking up of
eruptive rocks, or are built of the debris of previous erup-
tive or sedimentary rocks, or composed of extracts from
aqueous solution by crystallization, precipitation, or the
action of organic life. The accompanying figures, selected
from Mr. Forbes's article in the Popular Science Review,
well illustrate this method of investigation. Plate II,
Fig. 45, is a section of lava from Vesuvius, magnified
twrelve diameters, showing crystals of augite in a hard
gray rock. Plate II, Fig. 46, is a volcanic rock from
Tahiti, consisting of felspar, with olivine and magnetic
oxide of iron, and numerous crystals of a pyroxenic min-
eral. Plate II, Fig. 47, is pitchstone from a dyke in new

92 THE MICROSCOPIST.

red sandstone, magnified seventy-five diameters. Exter-
nally it resembles dirty green bottle-glass, but shows in
the microscope an arborescent crystallization of a green
pyroxenic mineral in a colorless felspar base. Plate II,
Fig. 48, shows auriferous diorite from Chili, consisting of
felspar, with hornblende and crystals of iron pyrites, mag-
nified thirty diameters. Plate II, Fig. 49, is a section of
granite from Cornwall, with crystals of orthoclase, hexag-
onal crystals of brown mica, and colorless quartz, which
a higher power shows to contain fluid cavities, magnified
twenty-five 'diameters. Plate II, Fig. 50, a volcanic rock
from Peru, composed of felspar, dark crystals of augite,
hexagonal crystals of dark mica, and a little magnetic
oxide of iron, magnified six diameters. Plate II, Fig.
51, lower Silurian roofing-slate, cut at right angles to the
cleavage, showing that the latter is not due to crystalline
but to mechanical arrangement, magnified two hundred
diameters. Plate II, Fig. 52, is an oolitic specimen from
Peru, regarded as an eruptive rock by D'Orbigny, but
shown in the microscope to be a mere aggregation of
sand, etc., without the crystalline character of eruptive
rocks.

Materials of Organic Origin. — Rocks and strata derived
from plants or animals may be arranged in four groups :
1. The calcareous, or those of which limestones have been
formed, as corals, corallines, shells, crinoids, etc. 2. The
siliceous, which have contributed to the silica, and may
have originated flints, as the microscopic shields of dia-
toms and siliceous spiculae of sponges. 3. The phosphatic,
as bones, excrement, etc. Fossil excrements are called
coprolites, and those of birds in large accumulations,
guano. 4. The carbonaceous, or those which have afforded
coal and resin, as plants.

To examine the structure of coal, it is necessary to have
very thin sections. From its friability, this is a process
of great difficulty. The Micrographic Dictionary recom-

PI ATE II.

Tig. 51x200

52 x 30

THE MICROSCOPE IN MINERALOGY AND GEOLOGY. 93

mends the maceration of the coal for about a week in a
solution of carbonate of potassium, when thin slices may
be cut with a razor. These should be gently heated in
nitric acid, and when they turn yellow, washed in cold
water and mounted in glycerin, as spirit and balsam ren-
der them opaque. Sometimes, as in anthracite, casts of
vegetable fibres may be obtained in the ash after burning
and mounted in balsam.

The lignites of the tertiary period show a vegetable
structure similar to the woods of the present period, but
the older coal of the palaeozoic series is a mass of decom-
posed vegetable matter chiefly derived from the decay of
coniferous wood, analogous to the araucarise, as is seen
from the peculiar arrangement of the glandular dots on
the woody fibres. Traces of ferns, sigillarise, calamites,
etc., such as are preserved in the shales and sandstones of
the coal period, are also met with, but their structure has
not been preserved.

Professor Heer, of Zurich, has described and classified
several hundred species of fossil plants from the rniocene
beds of Switzerland by the outlines, nervation, and micro-
scopic structure of the leaves and character of sections of
the wood. Several hundred kinds of insects also have
been found in the same strata. It is remarkable that a
great part of this fossil flora is such as is now common
to America, ^as evergreen oaks, maples, poplars, ternate-
leaved pines, and the representatives of the gigantic
sequoise of California.

The researches of palaeontologists have brought to light
nearly two thousand species of fossil plants, of which
about one-half belong to the carboniferous and one-fourth
to the tertiary formations.

The rapid multiplication of the minute microscopic
organisms called diatoms, is such that Professor Ehren-
berg affirms it to have an important influence in blocking
up harbors and diminishing the depth of channels. These

94 THE MICROSCOPIST.

organisms, now generally regarded as plants, are exceed-
ingly small, and are usually covered by loricse or shields
of pure silica, beautifully marked, as if engraved. These
loricse or shells having accumulated in great quantities,
have given rise to very extensive siliceous strata. Thus
the "infusorial earth" of Virginia, on which Richmond
and Petersburg are built, is such a deposit eighteen feet
in thickness. The polishing material called Tripoli, and

FIG. 53.

Fossil Diatomacese, etc., from Mourne Mountain, Ireland: a, a, a, Gaillomlla (Melo-
seira) procera, and G. granulata; d, d, d, G. biseriata (side view); 6, 6, Surirella plieata ;
c, S, craticula; k, S, calodouica; e, Gomphonema gracile; /, Cocconenia fusidium; g,
Tabellaria vulgaris; h, 1'innularia dactylus; i, P. nobilis; /, Synedra ulna. (From
Carpenter.)

the deposit called in Sweden and Xorway berg-mehl or
mountain flour, because used in times of scarcity to mix
with flour for bread, are similarly composed. Strata of
white rock in the anthracite region of Pennsylvania, and
from the sides of the Sierra Nevada and Cascade ranges
in California and Oregon, have also been found to consist
of such remains (Fig. 53).

THE MICROSCOPE IN MINERALOGY AND GEOLOGY. 95

The lowest type of animal life, consisting of minute
portions of sarcode or animal jelly, having the power of
putting forth prolongations of the body at will, contain
some forms which cover themselves with shells, usually
many-chambered, of carbonate of lime. From the pores
in these shells, through which the root-like processes of
sarcode are protruded, they are called Foraminifera.

FIG. 54.

Fossil Polycystina, etc., from Barbadoes: a, Podocyrtis mitra; 6, Rhabdolithus scep-
trutn ; c, Lychnocanium falciferum; d, Encyrtidium tubulus; e, Flustrella concentrica;
/, Lychnocanium lucerna; g, Encyrtidium elegans; h, Dictyospyris clathrus; i, Encyr-
tidium mongolfieri; A;, Stephanolithis spinescens; /, S, nodosa; m, Lithocyclia ocellus;
n, Cephalolithis sylvina; o, Podocyrtis cothurnata; p, Rhabdolithes pipa. (From Car-
penter.)

Another class, the Pofycystina, secrete a siliceous shell,
usually of one chamber. The accumulations of the Fo-
raminifera have formed our chalk beds, while the Polycys-
tina have contributed to siliceous strata, like the Diato-
macece (Fig. 54).

The origin of white chalk strata has been illustrated

96 THE MICROSCOPIST.

by the deep-sea soundings made preparatory to laying
the telegraph cable across the Atlantic Ocean. Professor
Huxley found the mud composing the floor of the ocean
to consist of minute Rhizopods or Foraminifera, of the
genus Glohigerina, together with Polycystina and Dia-
toms, and a few siliceous spiculse of sponges. These were
connected by a mass of living gelatinous matter, to which
he has given the name of Bathybius, and which contains
minute bodies termed Coccoliths and Coccospheres, which
have also been detected in fossil chalk. It is said that
95 percent, of the mud of the North Atlantic consists of
Globigerina shells.

To examine Foraminifera in chalk, rub a quantity to
powder in water with a soft brush, and let it settle for a
variable time. The first deposits will contain the larger
specimens, with fragments of shell, etc. ; the smaller fall
next, while the amorphous particles suspended in the
water may be cast aside. After drying such specimens
as may be selected by the use of a dissecting microscope
or Coddington lens, etc., they may be mounted in balsam.

The flint found in chalk often contains Xanthidia,
which are the sporangia of Desmidiacese, as well as speci-
mens of sponge, Foraminiferal shells, etc. They must be
cut as other hard minerals.

There are other deposits besides chalk which are seen
by the microscope to consist of minute shells, corals,
etc. A section of oolitic stone will often show that each
rounded concretion is composed of a series of concentric
spheres inclosing a central nucleus which may be a forami-
niferal shell. The green sand formation is composed of
the casts of the interior of minute shells which have them-
selves entirely disappeared. The material of these casts,
chiefly silex colored with iron, has not only filled the cham-
bers of the shells, but has penetrated the canals of the
intermediate skeleton.

The more recent discovery by Drs. Dawson and Carpen-

THE MICROSCOPE IN MINERALOGY AND GEOLOGY. 97

ter of the organic nature of those serpentine limestones
in the Laurentian formations of Canada and elsewhere,
which are products of the growth of the gigantic forami-
niferal Eozoon Canadense, over immense areas ©f the
ancient sea-bottom, is one of still greater interest both to
the student of Geology and of Biology.

This immense rhizopod appears to have grown one layer
over another, and to have formed reefs of limestone as do
the living coral-polyps. Parts of the original skeleton,
consisting of carbonate of lime, are still preserved, while
certain interspaces have been filled up with serpentine and
white augite.

Microscopic Paleontology. — As a general rule it is only
the hard parts of animal bodies that have been preserved
in a fossil state.

It will often occur that the inspection of a microscopic-
fragment of such a fossil will reveal with certainty the-
entire nature of the organism to which it belonged. Thus
minute fossil corals, the spines of Echinodermata, the
eyes of Trilobites, etc., will determine the position to
which we should ascribe the specimen, or a section of tooth
or bone will enable the rnicroscopist to assign the fossil to
its proper class, order, or family. Thus Professor Owen
identified by its fossil tooth, the Labyrinthodon of War-
wickshire, England, with the remains in the Wittemberg
sandstones, and declared it to be a gigantic frog with some
resemblances both to a fish, and a crocodile. This predic-
tion the subsequent discovery of the skeleton confirmed.

The minute structure of teeth differs greatly in differ-
ent animals. In the shark tribe of fishes the dentine is
very similar to bone, excepting that the lacunae of bone
are absent. In man and in the Garni vora the enamel is a
superficial layer of generally uniform thickness, while in
many of the Herbivora the enamel forms with the cemen-
tum a series of vertical plates which dip into the substance
of the dentine. Enamel is wanting in serpents, Edentata,

98 THE MICROSCOPIST.

and Cetacea. Such differences make it quite possible to
distinguish the affinities of a fossil specimen from a small
fragment of tooth.

In a similar way the microscopic characters of bone vary.
The bones of reptiles and fishes have the cancellated struc-
ture throughout the shaft, while the lacunse present very
great varieties, so that an animal tribe may be determined
by their measurement. In this way many contributions
have already been made to palaeontology.

CHAPTER VIII.

THE MICROSCOPE IN CHEMISTRY.

THE value of microchemical analysis, and the simplicity
of its processes, commend this department of microscopy
to general favor.

A large proportion of the actions and changes produced
by reagents may be observed as satisfactorily in drops as
in larger quantities. The decompositions effected by a
galvanic battery far smaller than that contained in a lady's
silver thimble, which deflected the mirror at the other end
of the Atlantic Telegraph Cable, may be readily observed
with a microscope.

Apparatus and Modes of Investigation.— A. few flat and
hollow glass slides, thin glass covers, test-tubes, small
watch-glasses, a spirit-Jamp or Bunsen's burner, constitute
nearly all the furniture which is essential.

Dr. Wormley* directs that a drop of the solution to be
examined should be placed in a watch-glass, and a small
portion of reagent added with a pipette. The mixture

* The Microchemistry of Poisons, by Dr. Worraley.

THE MICROSCOPE IN CHEMISTRY. 99

may then be examined with the microscope. If there is
no precipitate, let it stand several hours and examine again.
Dr. Beale prefers a flat or concave slide, and suggests that
if a glass rod be used for carrying the reagent, it must be
washed each time, or a portion may be transferred' from
the slide to the bottle. He also advises the use of small
bottles with capillary orifices for reagents. Dr. Lawrence
Smith uses small pipettes with the open end covered by
india-rubber.

If heat be required, the drop may be boiled on the slide
over a spirit-lamp, or a strip of platinum-foil or mica may
be held with forceps so as to get a red or white heat from
the lamp or a Bunsen burner. This is especially needed
to get rid of organic matters.

For the examination of earthy materials, as carbonate
or phosphate of lime, phosphate of ammonia and magne-
sia, sulphates or chlorides, a small fragment may be placed
on a slide and covered with thin glass. A drop of nitric
acid is then put near the edge of the cover. If bubbles
escape a carbonate is indicated. Neutralize the acid with
ammonia ; let the flocculent precipitate stand awhile ;
cover and examine with the microscope. After a time,
amorphous granules and prisms will show phosphates of
ammonia, magnesia, and lime. Sulphates are shown by
adding to the nitric acid solution nitrate of barytes, and
chlorides by nitrate of silver.

Dr. Beale recommends adding glycerin to the test solu-
tions. The reactions are slower but more perfect, and the
crystalline forms resulting are more complete.

If a sublimate be desired, a watch-glass can be inverted
over another, and the lower one containing the material,
as biniodide of mercury, etc., heated over a spirit-lamp,
or the sublimation may be made in a reduction-tube.

Preparation of Crystals for the Polariscope. — Many speci-
mens may be prepared by concentrating the solution with
heat and allowing it to cool. It should not be evaporated

100 THE MICROSCOPIST.

to dryness. Many salts may be preserved in balsam, but
some are injured by it, and need glycerin or castor oil as
a preserving fluid.

The method of crystallization may be modified in vari-
ous ways so as to obtain special results. Thus if a solu-
tion of sulphate of iron is suffered to dry on a slide, the
crystals will be arborescent and fern-like, but if the liquid
is stirred with a glass rod or needle while evaporating,
separate rhombic prisms will form, which give beautiful
colors in the polariscope. Pyrogallic acid also crystallizes
in long needles, but ai little dust, etc., as a nucleus, brings
about a change of arrangement resembling the "eye" of
the peacock's tail.

A saturated solution dropped into alcohol, if the salt is
insoluble in alcohol, will produce instantaneous crystals.

To obtain the best results, some crystals, as salicin,
should be fused on a slide over the lamp, and the matter
spread evenly over the surface. This may be done with
a hot needle. The temperature greatly affects the char-
acter of the crystallization. If very hot, the crystals run
in lines from a common centre. A medium temperature
produces concentric waves.

Many new forms result from uniting different salts in
different proportions. The knowledge of these different
effects can only be attained by experience.

Sections of crystals, as nitrate of potash, etc., to show
the rings and cross in the polariscope, are difficult to
make. After cutting a plate with a knife to about one-
fourth of an inch thick, it may be filed with a wet file to
one-sixth of an inch, smoothed on wet glass with fine
emery, and polished on silk strained over a piece of glass,
and rubbed with a mixture of rouge and tallow. The
nitre must be rubbed till quite dry, and the vapor of the
fingers prevented by the use of gloves.

For a general account of the use of polarized light, see
Chapter YI.

THE MICROSCOPE IN CHEMISTRY. 101

The Use of the Microspectroscope. — We have already de-
scribed this accessory in Chapter III. It promises im-
portant results in chemical analysis, but requires delicate
observation and exact measurements, together with a
careful and systematic study of a large number of colored
substances.

In using the microspectroscope, much depends on the
regulation of the slit. It should be just wide enough to
give a clear spectrum without irregular shading. As a
general rule, it should be just wide enough to show Frau-
enhofer's lines indistinctly in daylight. The slit in the
side stage should be such that the two spectra are of
equal brilliancy. No light should pass up the microscope
but such as has passed through the object under exam-
ination. This sometimes requires a cap over the object-
glass, perforated with an opening of about one-sixteenth
of an inch for a one arid a half inch objective.

The number, position, width, and intensity of the ab-
sorption-bands are the data on which to form an opinion
as to the nature of the object observed, and Mr. Sorby
has invented a set of symbols for recording such observa-
tions. (See Dr. Beale's How to Work with the Microscope.}
These bands, however, do not relate so much to the ele-
mentary constitution as to the physical condition of the
substance, and vary according to the nature of the solvent,
etc., yet many structures give such positive effects as to
enable us to decide with confidence what they are.

Colored beads obtained by ordinary blowpipe testing,
sections of crystals, etc., cut wedge-shaped so as to vary
their thickness, often give satisfactory results. But
minute quantities of animal and vegetable substances, as
blood-stains, etc., dissolved and placed in short tubes
fastened endwise on glass slides, or in some other conve-
nient apparatus, offer the most valuable objects of re-
search.

To measure the exact position of the absorption-bands,

102

THE MICROSCOPIST.

the micrometer already described may be used, or Mr.
Sorby's apparatus, giving an interference spectrum with
twelve divisions, made by two Mcol's prisms, with an
intervening plate of quartz of the required thickness.

The value of this mode of investigation in medical
chemistry, and for purposes of diagnosis or jurisprudence,
may be seen by the following illustrations:*

Pettenkofer's Test for Bile (Fig. 55).— To a few drops of
bile in a porcelain dish, add a drop of solution of cane-

A a P C

H TT

Pettenkofer's Bile-Test.

sugar, and then concentrated sulphuric acid drop by drop,
with agitation. The mixture becomes a purple-red color,
and shows a spectrum as in the figure. The color will
be destroyed by water and alcohol.

Tests for Blood. — Haematocrystalline, or cruorin, com-
posed of an albuminoid substance and hsematin, generally
crystallizes in tetrahedra or octahedra. In blood from

A a B C

H IT

Blood.

the horse and from man only an amorphous deposit is
found. The watery solution of this substance properly
diluted, shows two remarkable bands of absorption, and
obscuration of the blue and violet end of the spectrum
(Fig. 56). As the blood of all vertebrates shows the same

* See Thudichum's Manual of Chemical Physiology. New York, 1872.

THE MICROSCOPE IN CHEMISTRY.

103

bands, it is judged that hamate-crystalline is present in it
as such, and not formed from it. By treating a solution
of blood which exhibits the two absorption-bands with
hydrogen, or with a solution of ferrous sulphate contain-
ing tartaric acid and excess of ammonia, taking care to

A a E C

H H1

Reduced Haeiuatoerystalline.

exclude the air, the color of the solution changes to pur-
ple, and the spectroscope shows only one broad band in-
stead of two (Fig 57). Shaking with air will restore the
two bands. By treating blood with hydrothion or am-

FIG. 58.

A a B C

E 1)

H FT

TI

1

51

_.

Blood treated with. Amni

monium sulphide, three bands make their appearance, as
in Fig. 58.

Hsematin is seen by the microscope to consist of small

A n 7? fl

Four-banded Hsematin.

rhombic crystals. Dissolved in alcohol and a little sul-
phuric acid, the spectrum shows four, and under some
circumstances five, bands (Fig. 59). Rendered alkaline

104

THE MICROSCOPIST.

by caustic potash, one broad band appears (Fig. 60\
Acid will restore the former spectrum.

Dissolve haernatin in water with a little caustic potash.

A a 7?

JT 77'

iilii

Alkaline liaeuialin.

To a solution of ferrous sulphate, add tartaric acid and
then ammonia till alkaline. Pour a little of the clear
mixture into the hsematin solution. The spectrum of re-

A a B C

Reduced Haematin.

duced hsematin will show two bands (Fig. 61). Shaking
with air will restore the former spectrum.

Liutein Spectra. — The juice of the corpora lutea, to which
sulphuric acid and a little sugar is added, gives a fine

A a E C

Juice of Corpora Lutea with Sulphuric Acid.

purple color, and shows in the spectroscope one band in
the green (Fig. 62). Its chloroform solution, examined
with lime-light, shows two bands in blue (Fig. 63). An
alcoholic or ethereal solution gives a third one in the
violet.

THE MICROSCOPE IN CHEMISTRY.

105

Cysto lutein, or the yellow fluid of an ovarian cyst,
shows with the lime-lio;ht three bands in blue, in the

A a Ji

H IT

Chloroform Solution of Corpora Lutea.

same position as the chloroform solution of lutein (Fig.
64).

The serum of blood, etc., shows the bands of hsemato-

A a B C

Cysto-Luteiu from au Ovarian Cyst.

crystalline and one or two doubtful bands, as in the figure
(Fig. 65).

Dr. Richardson, of Philadelphia, gives the following
directions for examining blood-stains: Procure a glass
slide with a circular excavation, and moisten the edges
of the cavity with a small drop of diluted glycerin. Lay

A a B C

Sero-Lutein.

a clean glass cover, a little larger than the excavation, on
white paper, .and put on it the smallest visible fragment
of blood-clot. "With a needle, put on the centre of the
cover a speck of glycerin, not larger than a full stop (.),

106 THE MICROSCOPIST.

and with a dry needle push the blood to the edge that it
may he just moistened with the glycerin. Place the slide
on the cover so that the glycerin edges of the cavity may
adhere, and turning it over, transfer it to the stage of the
microscope. Thus a minute quantity of a strong solution
of hsemoglobulin is obtained, the point of greatest density
of which may be found by a one-fourth objective, and
tested by the spectroscopic eye-piece and with high powers.
The tiny drop may be afterwards wiped off with moist
blotting-paper, and a little fresh tincture of guaiacum
added, showing the blue color of the guaiacum blood-test.
Inverted Microscope of Dr. Lawrence Smith. — In ordinary
chemical investigations there is some risk of injuring the
polish of the lenses, as well as the brass work of the mi-
croscope, without very great care. This is particularly
the case in observing the effects of heat or of strong acids.
To obviate this difficulty, Dr. Lawrence Smith contrived
a plan for an inverted microscope, which has been con-
structed by Nachet of Paris. The optical part of the in-
strument is below the stage, and is furnished with a pecu-
liar prism, by which the rays from the objective are bent
into a conveniently inclined body. The illuminating ap-
paratus is above the stage. This construction renders the
instrument well adapted to chemical investigations.

GENERAL MICROCHEMICAL TESTS.

Dr. Wormley has directed attention to some necessary
cautions. He shows that many substances which may
readily be detected in a pure state, even in very minute
quantities by the microscope, are difficult to detect when
mixed with complex organic materials. This is especially
applicable to the alkaloids, which should be separated
from such mixtures by the use of the dialyzer — a hoop
with a bottom of parchment-paper, etc. — or extracted
with ether or chloroform.

THE MICROSCOPE IN CHEMISTRY. 107

The purity of all reagents should be carefully estab-
lished, and they should be kept in hard German glass
bottles, and only distilled water used in all our researches.

The true nature of a reaction that is common to several
substances may often be determined with the microscope.
Thus a solution of nitrate of silver becomes covered with
a white film when exposed to several different vapors, but
hydrocyanic acid is the only one which is crystalline.
This will detect 100,000th of a grain of the acid. A slip
of clean copper boiled in a hydrochloric acid solution of
arsenic, mercury, antimony, etc., becomes coated with the
metal, but when heated in a reduction-tube, arsenic only
yields a sublimate of octahedral crystals, and mercury
only will furnish metallic globules.

A solution of iodine produces distinct reaction with
100,000th of a grain of strychnine in solution in 1 grain
of water, but as this is common to other alkaloids, other
tests are needed. Yet the absence of such a reaction
shows the absence of the alkaloid.

The degree of dilution is important. Thus bromine with
atropin yields a crystalline deposit from 1 grain of a
20,000th or stronger dilution, but not with diluter solu-
tions. A limited quantity of sulphuretted hydrogen
throws down from corrosive sublimate a white deposit,
while excess produces a black precipitate.

Blue and Reddened Litmus Paper are used as tests for
acids and alkalies. It is a bibulous paper dyed in infu-
sion of litmus. The red is made by adding a little acetic
acid to the infusion. Dry substances and vapors require
the paper to be moistened with distilled water. If the
acid reaction depends on carbonic acid, warming the paper
on a slide over a lamp will restore the color. So if a
volatile alkali, ammonia or carbonate of ammonia, have
made the red paper blue, its color will be restored by a
gentle heat. Sometimes the infusion of litmus is more
convenient than the paper.

108 THE MICROSCOPIST.

Alcohol coagulates albuminous matter.

Ether dissolves fat.

Acetic Acid will dissolve phosphate or carbonate of lime,
but not the oxalate.

Nitrate of Barytes in cold saturated solution is a test for
sulphuric and phosphoric acids. The precipitated sulphate
of baryta is insoluble in acids and alkalies. The phosphate
is soluble in acids arid insoluble in ammonia.

Nitrate of Silver. — A solution of 60 grains to the ounce
of water is a convenient test for chlorides and phosphates.
Chloride of silver is white, soluble in ammonia and insolu-
ble in nitric acid. The tribasic phosphate of silver is yel-
low, and soluble in excess of ammonia or of nitric acid.

Oxalate of Ammonia is a test for salts of lime. Dissolve
the material in nitric acid, and add excess of ammonia.
Dissolve the flocculeut precipitate in excess of acetic acid,
and add the oxalate of ammonia. Oxalate of lime is in-
soluble in alkalies and acetic acid, but soluble in strong
mineral acids.

Iodine is a test for starch, coloring it blue. Albuminous
tissues are colored yellow, and vegetable cellulose a brown-
ish-yellow. The addition of sulphuric acid turns cellulose
blue.

DETERMINATION OF SUBSTANCES.
ALKALIES.

Bichloride of platinum precipitates from salts of potash
or ammonia a yellow double chloride, which crystallizes
in beautiful octahedra. It has no precipitating effect on
solutions of soda. Polarized light will distinguish the
800,000th of a grain of double chloride of sodium and
platinum by its beautiful colors from the chloride of
potassium and platinum, or of platinum alone. The
double chloride of platinum and potassium may be dis-
tinguished from that of ammonia by heating to redness,
treating with hot water, and acting on with nitrate of

THE MICROSCOPE IN CHEMISTRY. 109

silver. The ammonium compound after ignition leaves
only the platinum, which gives no precipitate with nitrate
of silver, while the potassium chloride yields a white pre-
cipitate of chloride of silver.

Antimoniate of potash throws down from solutions of
soda and its neutral salts a white crystalline antimoniate
of soda, the forms of which vary according to the strength
of the solution ; generally they are rectangular plates and
octahedra.

ACIDS.

Sulphuric. — In solutions acidulated with hydrochloric
or nitric acid, the chloride or nitrate of baryta produces
a white precipitate. Yeratrin added to a drop of concen-
trated sulphuric acid produces a crimson solution, or de-
posit if evaporated.

Nitric. — Heated with excess of hydrochloric acid elimi-
nates chlorine, which will dissolve gold leaf. A blood-
red color is produced when nitric acid or a nitrate is mixed
with a sulphuric acid solution of brucin.

Hydrochloric. — Nitrate of silver precipitates amorphous
chloride of silver; soluble in ammonia, but insoluble in
nitric and sulphuric acid.

Oxalic. — Nitrate of silver precipitates amorphous oxa-
late of silver ; soluble in nitric acid and also in solution
of ammonia.

Hydrocyanic. — Put a drop of acid solution .in a watch-
glass, invert another over it containing a drop of solution
of nitrate of silver, and a crystalline film will form. A
solution of hydrocyanic acid treated with caustic potash
or soda and then with persulphate of iron yields Prussian
blue.

Phosphoric. — A mixture of sulphate of magnesia, chlo-
ride of ammonium, and free ammonia produces in solu-
tions of free phosphoric acid and alkaline phosphates
white feathery or stellate crystalline precipitate of ammo-

110 THE MICROSCOPIST.

nio-phosphate of magnesia. A slower crystallization gives
prisms.

METALLIC OXIDES.

These may usually be determined by treating a small
portion of solution, acidulated with hydrochloric acid, by
sulphuretted Irydrogen ; another, and neutral portion with
sulphuret of ammonium ; and a third with carbonate of
soda.

Antim.ony. — Sulphuretted hydrogen throws down or-
ange-red precipitate from tartar-emetic solutions, etc.

Arsenic yields white octahedral crystals of arsenious
acid when sublimed. Arsenious acid may be reduced to
metallic arsenic by heating to redness in a tube with
charcoal and carbonate of soda. A solution of arsenious
acid yields octahedral crystals by evaporation, so as to
determine with the microscope 1000th to 10,000th of a
grain.

Ammonio-nitrate of silver throws down from an aque-
ous solution of arsenious acid a bright yellow precipitate,
arnmonio-sulphate of copper a green precipitate, and sul-
phuretted hydrogen a bright yellow.

Mercury. — Bichloride of mercury, moistened with a drop
of solution of iodide of potassium, assumes the bright
scarlet color of biniodide of mercury. A strong solution
of caustic potash or soda turns bichloride of mercury yel-
low from the formation of protoxide ; but calomel or chlo-
ride of mercury is blackened from formation of suboxide.
Heated in a reduction-tube with dry carbonate of soda,
the sublimate shows under the microscope small, opaque,
spherical globules of mercury. Dr. Wormley states that
a globule of mercury or "artificial star" may be discrim-
inated by the one-eighth objective if it be but the
25,000th of an inch in diameter, weighing about the
9,000,000,000th of a grain; globules of ^^th of an inch
diameter weigh about 70,000,000th of a grain.

THE MICROSCOPE IN CHEMISTRY. Ill

Lead. — Sulphuretted hydrogen gives a hlack amor-
phous deposit. Sulphuric and hydrochloric acids yield a
white precipitate. Chloride of lead crystallizes in needles.
Iodide of potassium gives a bright yellow precipitate, sol-
uble in boiling wrater, and crystallizing in six-sided plates.
Bichromate of potassium yields a bright yellow amor-
phous deposit.

Copper. — Sulphuretted hydrogen gives a brown or black-
ish deposit ; ammonia a blue or greenish-blue amorphous
precipitate, or in dilute solutions a blue color to the liquid ;
caustic alkali, a similar precipitate, which on boiling in
excess of reagent becomes black, bttt if grape-sugar, or
some other organic agents, be present, a yellow or red
precipitate of suboxide of copper occurs. Arsenite of
potassium produces a bright green.

Zinc. — Sulphuretted hydrogen gives a white amorphous
deposit — the only white sulphuret. Alkalies produce a
white hydrated oxide of zinc.

ALKALOIDS.

The editors of the Micrographic Dictionary refer to a paper
of Dr. T. Anderson, in the Edinburgh Monthly Journal,
where he shows that the microscope readily distinguishes
the more common alkaloids from each other by the form
of their crystals and of their sulphocyanides. The alka-
loids are first dissolved in dilute hydrochloric acid, then
precipitated on a glass plate with a solution of ammonia,
or if the sulphocyanide is required, with a strong solution
of sulphocyanide of potassium. It may then be placed
under the microscope. The solution should not be too con-
centrated. This branch of investigation has been greatly
promoted by the elegant work of Dr. Wormley, already
referred to, on the Microchemistry of Poisons.

Atropin. — Ammonia throws down an amorphous pre-
cipitate. One grain of a T^th grain solution yields to

112 THE MICROSCOPIST.

caustic potash or soda a precipitate which, when stirred
with a glass rod, becomes a mass of crystals, as in Plate
til, Fig. 66. The Sulphocyanide of potassium gives no
precipitate.

Aconitin. — No characteristic test, except the physiologi-
cal one; yo^th of a grain produces on the end of the
tongue a peculiar tingling and numbness, lasting for an
hour; TJotn grain in alcohol, rubbed on the skin, pro-
duces temporary loss of feeling.

Brucin or Bruda. — Potash or ammonia produces stellar
crystals. Sulphocyanide of potassium, feathery, or sheaf-
like. (Plate III, Fig. 67.) Nitric acid produces a blood-
red color, changing to yellow by heat. On cooling the
latter and adding protochloride of tin, it becomes a beau-
tiful purple. Ferricyanide of potassium, with T ^ Oth grain
of brucin yields the most brilliant polariscope crystals.
(Plate III, Fig. 68).

Cmchonine. — Ammonia produces granular radiating
crystals. (Plate III, Fig. 69.) Sulphocyanide of potas-
sium six-sided plates, some irregular. (Plate III, Fig. 70.)

Conine. — This alkaloid and nicotin are distinguished
from other alkaloids by being liquid at ordinary tempera-
tures, and by their peculiar odor. Conine may be known
from nicotin by its odor and sparing solubility in water,
by yielding crystalline needles to the vapor or solution of
hydrochloric acid, a white precipitate with corrosive sub-
limate, and a dark-brown precipitate with nitrate of silver.

Codein. — Ammonia or alkalies give a white amorphous
deposit. Sulphocyanide of potassium, crystalline needles.
A solution of iodine in iodide of potassium, a reddish-
brow^ precipitate, which becomes crystalline. This is
soluble in alcohol, from which it separates in plates (Plate
III, Fig. 71), which appear beautiful in the polariscope.

Daturin. — According to Dr. Wormley, this is identical
with atropin.

Narcotin. — In its pure state crystallizes in rhombic

PLATE III.

FIG. 66.

FIG. 67.

* *

FI0.71.

^
\>

FIG. 72.

**

FIG. 73.

FIG. 74.

FIG. 70.

o , O

O

FIG. 75.

THE MICROSCOPE IN CHEMISTRY. 113

prisms, or oblong plates. Ammonia, the alkalies, and their
carbonates produce tufts of crystals (Plate III, Fig. 7^).
A drop of aqueous solution of a salt of narcotin, exposed
to vapor of ammonia, is covered with a crystalline film if
it only contains g^^th of its weight of alkaloid.

Morphine. — When pure crystallizes in short rectangular
prisms. Sulphuric acid dissolves them, and if bichromate
of potash be added, green oxide of chromium results. Con-
centrated nitric acid turns it orange-red, and dissolves it.
A strong solution treated with a strong solution of nitrate
of silver and gently heated, decomposes the latter and pro-
duces a shining crystalline precipitate of metallic silver,
In dilute solutions, alkalies precipitate a crystalline form
(Plate III, Fig. 73). No precipitate with sulphocyanide-
of potassium unless highly concentrated.

Quinine. — Amorphous precipitate with ammonia. Su'l-
phocyanide of potassium gives irregular groups of acicu^
lar crystals, like those produced by strychnine, but longer
and more irregular (Plate III, Fig 74\ The solution
should be dilute, and twenty-four hours allowed for the
crystals to form.

The iodo-disulphate, or Ilerapathite, gives crystals of a
pale olive-green color, which possess a more intense polar-
izing power than any other known substance. Dr. Hera-
path proposed this as a delicate test for quinine. A drop
of test-liquid — made with 3 drachms of acetic acid, 1
drachm of rectified spirits, and 6 drops of dilute sulphuric
acid — is placed on a slide and the alkaloid added. When
dissolved a little tincture of iodine is added, and after a
time the salt separates in little rosettes. By careful manip-
ulation crystals of this salt may be formed large enough
to replace Nicol's prisms or tourmaline plates in the polar-
izing apparatus. When the crystals of Ilerapathite cross
each other at a right-angle, complete blackness results.
Intermediate positions give a beautiful play of colors.

Strychnine. — Ammonia gives small prismatic crystals,

8

114 THE MICROSCOPIST.

some crossed at 60° (Plate III, Fig. 75). Sulphocyanide
of potassium produces flat needles, often in groups. Iodine
in iodide of potassium gives a reddish-brown amorphous
precipitate, crystalline in dilute solutions. When pure,
strychnine appears in colorless octahedra, lengthened
prisms or granules. To a solution of the alkaloid or its
salts in a drop of pure sulphuric acid, which produces no
-color, add a small crystal of bichromate of potash, and
•stir slowly with a pointed glass rod. A blue color will
appear, passing into purple, violet, and red. The bright
yellow crystals of chromate of strychnia, if dried and
touched with sulphuric acid, will also show the color test.
This is said to be delicate enough to show Y^n'ooTj^ °*' a
grain of strychnine. The tetanic convulsions of frogs im-
mersed in a solution of strychnine, or after injections of
the solution in lungs or stomach, etc , is also a very deli-
cate test.

Veratrin and its salts treated in the dry state with con-
centrated sulphuric acid, slowly dissolve to a reddish-yel-
low, or pink solution, which becomes crimson-red. The
process is accelerated by heat.

Narcein, touched with the cold acid, becomes brown,
brownish-yellow, and greenish-yellow, and if heated, a
dark purple-red.

Solanin turns orange-brown, and later purplish-brown.

Piperin turns orange-red to brown.

Salicin gives to the acid a crimson pink, changing to
black.

Papaverin gives a fading purple.

CRYSTALLINE FORMS OF VARIOUS SALTS.

Our limits forbid extended description, yet a few forms
of frequent recurrence will be useful to the student. For
crystals in plants or from animal secretions reference may
be made also to succeeding chapters.

Salts of Lime. — The carbonate sometimes occurs in ani-

PLATE IV.

FIG. 76.

I

FIG. 80.

\

FIG. 77.

FIG. 81.

8*

FIG. 78.

'

FIG. 82.

FIG. 79.

FIG. 83.

FIG. 84.

THE MICROSCOPE IN CHEMISTRY. 115

mal secretions in the form of little spheres or disks, con-
sisting of groups of radiating needles. In otoliths it is
often in minute hexagonal prisms with trilateral summits.
It is deposited from water in irregular forms, all of which
are grouped needles. Sometimes it assumes the rhombo-
hedral form, as in the oyster shell (Plate IV, Fig. 76).
In any doubtful case, test as described at pages 99 and
108.

Lactate of Lime gives microscopic crystals, consisting of
delicate radiating needles (Plate IV, Fig. 77).

Oxalate of Lime occurs as square flattened octahedra,as
square prisms with quadrilateral pyramids, as fine needles,
and as ellipsoidal flattened forms, sometimes constricted
so as to resemble dumb-bells (Plate IV, Fig. 78).

Phosphate of Lime is usually in the form of thin rhombic
plates (Plate IV, Fig. 79).

Sulphate of Lime rapidly formed, as in chemical testing,
gives minute needles or prisms (Plate IV, Fig. 80). When,
more slowly formed, these are larger and mixed with
rhombic plates.

Soda Salts. — Chloride of Sodium or common salt gener-
ally forms a cube, terminated by quadrangular pyramids
or depressions (Plate IV, Fig. 81). The crystals do not
polarize light.

Plate IV, Fig. 82, represents crystals of oxalate of soda,
and Plate IV, Fig. 83, those of nitrate.

Magnesia Salts. — Ammonio-phosphate, or triple phosphate,
is often found in animal secretions. The most common
form is prismatic, but sometimes it is feathery or stellate
(Plate IV, Fig. 84).

Sulphate of Magnesia forms an interesting polarizing
object.

A most instructive series of salts may be made by
rapidly crystallizing some on glass slides, and allowing
others to deposit more slowly. In this way a set of speci-
mens may be prepared for comparison.

116 THE MICROSCOPIST.

CHAPTER IX.

THE MICROSCOPE IN BIOLOGY.

THE science of biology (from /9<«c, life), which treats of
the forms and functions of living beings, would be crude
and imperfect without the aid of the microscope. What-
ever might be learned by general observation, we should
miss the fundamental laws of structure and the unity
•which we now know pervades distant and ap'parently
different organs, as well as distinct species, if we were
deprived of the education which microscopy gives the
eye and hand.

The evident differences between living and non-living
bodies led to ancient theories of life which are still influ-
ential in modern thought, but neither microscope nor
scalpel nor laboratory have revealed the mystery which
seems ever to beckon us onward to another and entirely
different sphere of existence. Hippocrates invented the
hypothesis of a principle (<pu<ns, or nature) which influences
the organism and superintends it with a kind of intelli-
gence, and to which other principles (tuvape^ powers) are
subordinated for the maintenance of various functions.
This was also the theory of Aristotle, who gave the name
of soul (<f'u%y) to the animating principle.

Paracelsus and the chemical philosophers, from the
fifteenth to the seventeenth century, maintained that all
the phenomena of vitality may be explained by chemical
laws. To these succeeded the mathematical school under
Bellini (A.D. 1645), who taught that all vital functions
may be explained by gravity and mechanical impulse.
These theories were supplanted by those of the physiolo-
gists. Van Helmont revived the Hippocratian idea of a
specific agent, which he called archeus. This was more
fully elaborated by Stahl, who taught that by the opera-

THE MICROSCOPE IN BIOLOGY. 117

tion of an immaterial animating principle or soul (anima\
all vital functions are produced. The vis medicatrix na-
tures of Cullen was an attempt to compromise between
the rival theories of a superadded principle and a special
activity in organized matter itself.*

Harvey, Hunter, Miiller, and Prout proposed hypotheses
similar to those of Aristotle and Hippocrates, and many
modern scientific men accept similar views. The recent
doctrine of the correlation of physical forces has, however,
revived the mechanical and chemical theories, and the
industry with which these views have been propagated
has gained many adherents.

It is to be regretted that philosophy should assume the
name of science and dogmatize under that appellation.
The object of science is to state facts, and not to dream,
yet such is the nature of man's intellect that it will seek
to account for facts, and is thus drawn into metaphysical
speculation. If the age-long controversy between the
physicists and the vitalists is ever to cease, it will prob-
ably be through the microscopic demonstration of the
absolute difference between living and non-living matter.

In the present chapter it is designed to set forth briefly
the principal facts of elementary biology as they have
been brought to light by microscopy. For further illus-
trations in vegetable and animal histology, reference may
be made to following chapters.

1. All biologists agree that the elementary unit in living
bodies is the cell. This, according to the most recent in-
vestigations, is a soft, transparent, colorless, jelly-like par-
ticle of matter, which may be large enough to be just dis-
cernible to the naked eye, or so small as to be invisible
with our best instruments. The simplest or most elemen-
tary forms of vegetable or animal life consist of single
cells, while the more complex organisms are built up of

* Compare Bostock's History of Medicine.

118 THE MICROSCOPIST.

great numbers of these cells with the materials which
they have produced and deposited.

Haller, who has been called the father of modern physi-
ology, seems first to have conceived, though vaguely
(A.D. 1766), the idea of the essential unity of vital struc-
ture.

In 1838, Schleiden and Schwann wrote on the elemen-
tary cell, the former treating of the vegetable, and the
latter of the animal cell. From this time may be dated
the origin of the cell doctrine. Much importance was
assigned to the distinction between cell-wall, cell-con tents,
nuclei, and nucleoli.

In 1835, Dujardin discovered in the lower animals a
contractile substance capable of movement, to which he
gave the name of sarcode.

In 1861, Max Schultze showed that sarcode is analo-
gous to the body or contents of animal cells, and that on
this account the infusorial animalcules possessed of inde-
pendent life were simple or compound.

Examinations of this structure were made by numerous
observers, and the identity of many of its properties in
animals and vegetables established. To this structure
the name of protoplasm, rather than sarcode, has been
assigned. As this term has been somewhat loosely used,
so as to refer to it either in the dead or living state, Dr.
Beale has proposed the term bioplasm for elementary struc-
ture while living, and has given a generalization from
observed facts which has attracted much attention. He
distinguishes in all organic forms three states of matter:
First. Germinal matter or bioplasm, or matter which is
living. Second. Matter which was living, or formed mate-
rial. Third. Matter about to become living, or pabulum.

Schleiden and Schwann considered the cell as a growth
from a nucleus, and to consist of a cell-wall and cavity.
In vegetable cells there seemed to be an external wall of
cellulose, within which was another, the primordial utri-

THE MICROSCOPE IN BIOLOGY. 119

cle. But it has since been shown that the appearance of
the primordial utricle is caused by the protoplasm or bio-
plasm lying in apposition with the inner surface of the
cell-wall. In the cryptogamia, cells are known to occur
in which no nucleus is visible. Max Schultze and Hackel
have also discovered non-nucleated forms of animal life.
The idea of nucleus and cell-wall as essential to a cell is
therefore abandoned. Nuclei are regarded as new centres
of living matter, or minute particles of such matter capa-
ble of independent existence. Some of these masses are
so small as to be barely visible with the one-fiftieth objec-
tive under a magnifying power of five thousand diameters.

2. The structure and formation of a simple cell may be
illustrated by Plate V, Figs. 85 to 89, after Beale.* The
earliest condition of such a living particle is shown in
Plate Y, Fig. 85. If the external membrane of a fully
developed spore or any of the growing branches (Plate Yy
Figs. 86 to 89) be ruptured, such particles would be set
free in vast numbers.

The surface of such a particle becomes altered by con-
tact with external agencies. A thin layer of the external
surface is changed into a soft membrane or cell-wall,
through which pabulum passes and undergoes conversion
into living matter, which thus increases. The increase
of size is not owing to the addition of new matter upon
the external surface, but to the access of new matter in-
teriorly. The thickness of the formed material depends
on external circumstances, as temperature, moisture, etc.
If these be unfavorable to the access of pabulum, layer
after layer of living matter will die or be deposited, as in
Plate Y, Figs. 87 and 88. If such a cell be exposed to
circumstances favorable to growth, the accession of fresh
pabulum will cause portions of living matter to make

* Physiological Anatomy and Physiology of Man, by Drs. Todd, Bow-
man, and Beale. New edition.

120 THE MICROSCOPIST.

their way through natural pores or chance fissures and
protrude, as in the figures.

3. The peculiar phenomena of living cells or bioplasms
may be classified as follows: Active or spontaneous move-
ment, nutrition and growth, and the power of reproduc-
tion. These vital actions, according to Dr. Beale, occur
in the bioplasm only, while the formed material, or non-
living matter, is the seat of physical and chemical changes
exclusively. Physical processes, as diffusion and osmose,
occur in bioplasmic particles, but the peculiar phenomena
referred to, and which are properly termed vital, do not
occur in non-living matter.

Movements of Cells. — Granules imbedded in the bioplasm,
either formed material or accidental products, enable our
microscopes to observe internal movement, while change
of form and of place exhibit the movement of the entire
cell.

The granular movement is either vibratory or continu-
ous. The vibrations of the granules appear similar to the
molecular movement described by Dr. Robert Brown in
1827, and which is common to all small masses of matter,
organic or inorganic. Minute cells may thus dance in
fluid as well as fine powders, etc. Such movements occur,
however, in the interior of living cells, and may possibly
be connected with vitality. In the salivary corpuscles,
the dancing motion ceases on the addition of a solution
of one-half to one per cent, of common salt, while such
addition has no influence of the kind on fresh pus or
lymph.

The continuous granular motion is either a relatively
slow progression, corresponding to the change of form in
the cell, or a swifter flowing movement. Max Schultze
thus describes this motion in the threads of sarcode pro-
jected from the apertures of a Foraminiferal shell: " As
the passengers in a broad street swarm together, so do
the granules in one of the broader threads make their

PLATE V.

FIG. 85.

Minute particles of Bioplasm. From
Mildew, sVth in. Obj.

FIG. 88.

Passage of Germinal-matter through
pores in the formed material. X 1800.

FIG. 86.

FIG. 89.

m

Production of formed-material on
surface of Bioplasm. X 1800.

Production and accumulation of
Formed-material on Bioplasm. Epi-
thelium of cuticle. X 700.

FIG. 87.

FIG. 90.

Further production of formed-
material. At a is the budding
Bioplasm, passing through pores
in the formed-material. X 1800.

Amoebce from organic infusion.

THE MICROSCOPE IN BIOLOGY. 121

way by one another, oftentimes stopping and hesitating,
yet always pursuing a determinate direction correspond-
ing to the long axis 'of the thread. They frequently be-
come stationary in the middle of their course, and then
turn round, but the greater number pass to the extreme
end of the thread, and then reverse the direction of their
movement." No physical or chemical action with which
we are acquainted will account for such motions, which
have no analogy in unorganized bodies.

Changes of form are most strongly marked in the lower
forms of animal life, although occurring also in the sim-
pler vegetables, as the volvox. The Amoeba or Proteus is
typical of such changes, which have hence been termed
Amoeboid (Plate V, Fig. 90). When an Amoeba meets
another animal which is too slow to escape, it sends out
projections which encircle its prey; these coalesce, and
invest the whole mass with its bioplasm. It maintains
its grasp till it has abstracted all the portions which are
soluble, and then relaxes its hold.

Amoeboid cells in higher animals rarely move so rapidly
as the Amoeba itself. Their motions are limited to a
gradual change of form or to the protrusion of processes
in the form of threads, or tuberosities, or tufts, which
either drag the rest of the body after them or are again
withdrawn.

Cells of bioplasm rnay not only change their form, but
may wander from place to place by protruding a portion
of their mass, which drags the rest after it. The discov-
ery of wandering cells in the higher organisms, as man,
has opened quite a new and important field of physiologi-
cal and pathological research.

The movements of bioplasm may be changed, acceler-
ated, retarded, or stopped by a variety of stimuli, mechani-
cal, electrical, chemical, and nervous. Gentle warmth and
moisture are necessary to their perfection.*

* See Strieker's Manual of Histology.

122 THE MICROSCOPIST.

The nutrition and growth of the living cell has already
been described as the conversion of pabulum into bioplasm
or living matter. The subject of reproduction will be ex-
amined below under the head of cell-genesis.

4. The microscopic demonstration of bioplasm may be
effected by the use of an alkaline solution of coloring

'matter, as carmine. (See Chapter Y.) As bioplasm pos-
sesses an acid reaction, the alkali is neutralized and the
color retained. This process, however, is rather a dem-
onstration of the protoplasm which was recently alive.
For living cells or bioplasm, we must depend on supplying
them artificially with colored food. Thus indigo, carmine,
etc., in fine particles, added to the pabulum of cells or
liquid media in which they float, will be taken into the
interior of the bioplasm by the nutritive process. In this
way Recklinghausen showed the migration of pus-corpus-
cles.

"Welcker and Osborne were the first to use a solution
of carmine in order to stain the nuclei of tissues. They
were followed by Gerlach and Beale, the latter of whom
has greatly improved the process and shown its signifi-
cance.

5. The chemistry of cells and their products is an essential
part of biology, but would lead us too far from our subject
to discuss, yet a few points may not be irrelevant.

The chemical composition of bioplasm consists essen-
tially of oxygen, hydrogen, nitrogen, and carbon. Other
elements are often present and important, but not essen-
tial. Of the relation of these elements we know nothing,
save that they are in a state of constant vibration or
change. Dr. Beale considers it doubtful if ordinary chemi-
cal combination is possible while the matter lives. Analy-
sis in the laboratory is only possible with the compounds
resulting from the death of the cell.

When living or germinal matter is converted into formed
material, a combination of its elements takes place, often

THE MICROSCOPE IN BIOLOGY. 123

with very complex results, the nature of which has hitherto
baffled the efforts of chemists to determine. When the
life of germinal matter, however, is suddenly destroyed,
or rather when the matter is first transformed, the com-
pounds resulting from various species have similar chemi-
cal composition and properties, and an acid reaction is
developed. Fibrin, albumen, water, and certain salts may
thus be obtained from every kind of germinal matter.
Fatty matters also result, which continue to increase in
quantity for some time after death. In slow molecular
death, a certain amount of oxygen is taken into combina-
tion, which gives rise to different results from those which
occur when life is suddenly destroyed. Still other com-
binations are due to vital actions which are not yet under-
stood. Thus some bioplasm produces muscle; other par-
ticles originate nerve structure, cartilage, bone, connective
tissue, etc. Many chemical changes occur also in formed
material after its production. It may become dry or fluid,
or split up into gaseous or soluble substances as soon as
produced. Imperfect oxidation may lead to the formation
of fatty matters, uric acid, oxalates, sugar, etc. At the
earliest period of development, the formed material con-
sists principally of albuminous and fatty matters, with
chlorides, alkaline and earthy phosphates. At a later
period gelatin, with amyloid or starchy matter, is pro-
duced.*

6. Varieties in the form and Function of Bioplasm.. —
Mutability of shape is characteristic of amoeboid cells,
and no conclusions can be drawn from their appearance
after death. Where numbers of them are accumulated,
they are flattened by mutual pressure so as to appear
polyhedral, laminated, or prismatic. The upper layers of
laminated epithelium are usually flattened. Where cells
line the interior of cavities in a single layer, they form

* See Physiological Anatomy, by Todd, Bowman, and Beale.

124 THE MICROSCOPIST.

plates of different shape (endothelial cells), or cells in which
the long axis predominates (cylindrical epithelium), or
forms which are intermediate between plates and cylin-
ders. Some cells appear ramified or stellate, as in the
cells from the pith of a rush, bone-cells, and corpuscles of
the cornea. Others may become extraordinarily elongated,
as in the formation of fibre, muscle, etc. Some cells are
provided with cilia, which are limited to one portion of
the surface, and project their free extremities into the
cavity which they line. Dr. Beale considers the cilia to
be formed material, and their movements not vital, but a
result of changes consequent on vital phenomena.

Every living organism, plant, animal, or man, begins
its existence as a minute particle of bioplasm. Every
organic form, leaves, iiowers, shells, and all varieties of
animals ; and every tissue, cellular, vesicular, hair, bone,
skin, muscle, and nerve, originates by subdivision and
multiplication and change of bioplasm, and the trans-
formation or metamorphosis of bioplasm into formed ma-
terial. It is evident, therefore, that there are different
kinds of bioplasm indistinguishable by physics and chem-
istry, but endowed with different powers.*

7. Cell-Genesis. — Schleiden first showed that the em-
bryo of a flowering plant originates in a nucleated cell,
and that from such cells all vegetable tissues are devel-
oped. The original cells were formed in a p&sma or blas-
tema, commonly found in pre-existing cells, the nuclei first
appearing and then the cell-membrane. These views were
applied by Schwann to animal structure. The latter be-
lieved that the extra-cellular formation of cells, or their
origin in a free blastema, was most frequent in animals.
The researches of succeeding physiologists have, however,
led to a general belief that all cells originate from other
cells.

* Beale's Bioplasm.

THE MICROSCOPE IN BIOLOGY. 125

The doctrine of spontaneous generation or aUogenesis
has been the object of considerable research, but the bril-
liant experiments of Pasteur have shown that when all
access of living organisms into fluids is prevented, no de-
velopment of such organisms can be proved in any case
to occur. If the access of air, for instance, to a liquid
which has been boiled, is filtered through a plug of cotton-
wool, no living forms will appear in the liquid, but on
examination, such forms will be found in considerable
numbers in the cotton-wool, proving the presence of these
forms or their germs in the external air. Recent experi-
ments also render it probable that some cell-germs are
indestructible by a heat far exceeding that of boiling
water.

There are three forms of cell-multiplication, by fission,
by germination or budding, and by internal division. The
latter mode is termed endogenous. In it new cells are
produced within a parent-cell by the separation of the
bioplasm into a number of distinct masses, each of which
may become a new cell, as in the fecundated ovum.

Fission, or the division by cleavage of a parent-cell- into
two or four parts, may be regarded as a modification of
endogenous cell-multiplication. A good example of it
may be seen in cartilage.

Budding or germination consists in the projection of a
little process or bud from the mass of bioplasm, which is
separated by the constriction of its base, and becomes an
independent cell.

8. Reproduction in the higher organisms consists essen-
tially of the production of two distinct elements, a. germ-
cell or ovum, and a sperm-cell or spermatozoid, by the
contact of which the ovum is enabled to develop a new
individual. Sometimes these elements are produced by
different parts of the same organism, in which case the
sexes are said to be united, and the individual is called
hermaphrodite, androgynous, or monoecious. In other in-

126 THE MICROSCOPIST.

stances the sexes are distinct, and the species are called
dioecious.

9. The alternation of generations is a term given in bi-
ology to express a form of multiplication which occurs in
some of the more simple forms of life. It consists really
of the alternation of a true sexual generation with the
phenomenon of hudding. Thus a fern spore gives rise, by
budding and cell-division, to a prothallium ; this produces
archegonia and antheridia, as the sexual elements are
called, and the embryo which results from sexual union
produces not a prothallium but a fern. This phenomenon
is better seen in the Hydrozoa. In these the egg produces
a minute, ciliated, free-swimming body, which attaches
itself, becomes tapering, develops a mouth and tentacles,
and is known as the Hydra tuba. This multiplies itself,
and produces extensive colonies by germination, but under
certain circumstances divides by fission and produces
Medusce, which develop ova.

10. Parthenogenesis designates the production of new
individuals by virgin females without the intervention of
a male. It has also been applied to germination and
fission in sexless beings. In the Aphides, ova, are hatched
in spring, but ten or more generations are produced vi-
viparously and without sexual union throughout the sum-
mer. In autumn, however, the final brood are winged
males and wingless females, from whose union ova are
produced in the ordinary manner.

11. Transformation and metamorphosis relate to certain
changes or variations of development in the structure and
life history of an individual. Thus an insect is an egg or
ovum, a caterpillar or larva, a pupa or chrysalis, and an
imago or perfect insect, and these changes of condition
and structure constitute its development. Much difficulty
is caused by the phenomena of metamorphosis in assign-
ing the place of different species, transformations being
often mistaken for specific differences. It was formerly

THE MICROSCOPE IN BIOLOGY. 127

supposed that every animal passed through, in its devel-
opment, a series of stages in which it resembled the infe-
rior members of the animal scale, and systems of zoology
were proposed to be founded on this dream of embryology.
Careful research, however, has shown that larval changes
present many variations. In some the young exhibit the
conditions of adults of lower animals. Thus the Eolis, a
univalve shell fish, in its young state has all the charac-
teristics of a Pteropod, a free-swimming mollusk. Some-
times development is retrograde, and the adult is a de-
graded form as compared with the larva, thus setting at
nought all our theories, and teaching us that it is better
to observe than to imagine.

12. Discrimination of Living Forms. — We have seen,
section 6, that there are different kinds of living matter
endowed with different powers. We have also seen, sec-
tion 7, how varied are the forms of multiplication. Yet
when we come to discriminate between animal and vege-
table life, we find it exceedingly difficult, especially in
their more simple forms. Neither form, nor chemical
composition, nor structure, nor motive power, affords suf-
ficient grounds for discrimination. Yet when we consider
the functions of bioplasm in its varied forms, we may con-
veniently group all living beings in three great divisions,
viz.,/im#i, plants, and animals.

The bioplasm of the plant finds its pabulum in merely
inorganic compounds, while that of the animal is prepared
for it, directly or indirectly, by the vegetable. The func-
tion of fungi appears to be the decomposition of the formed
material of plants and animals by the means of fermenta-
tion or putrefaction, since these latter processes are depen-
dent on the presence of fungi. Thus by bioplasm are the
structures of plants and animals reared from inorganic
materials, and by bioplasm are they broken down and
restored to the inanimate world.

128 THE MICROSCOPIST.

CHAPTER X.

THE MICROSCOPE IN VEGETABLE HISTOLOGY AND BOTANY.

HISTOLOGY (from faros, a tissue) treats of formed mate-
rial, or the microscopic structure resulting from the trans-
formation of germinal or living matter. The nature of
this transformation is partly physical and partly vital,
and, as already stated, is often so complex as to baffle all
chemical analysis. Some light, however, has been thrown
on this subject by the modification of ordinary crystalline
forms when inorganic particles aggregate in the presence
of certain kinds of organic matter. To this mode of form-
ation the name of molecular coalescence has been given.
Mr. Rainey and Professor Harting contemporaneously
experimented with solutions of organic colloids, and found
that the crystallization of certain lime salts, as the car-
bonate, was so modified by such solutions as to resemble
many of the calcareous deposits found in nature. These
researches leave little doubt but that a majority of calca-
reous and silicious organic forms may be thus accounted
for. Such changes are rather physical than vital.

Cell-substance in Vegetables. — The protoplasm or bio-
plasm in vegetable-cells cannot be distinguished from ani-
mal usarcode" or protoplasm except by the nature of the
pabulum or aliment necessary to its nutrition. The vege-
table, under the stimulus of light, decomposes carbonic
acid, and acquires a red or green color from the compounds
which it forms, while the animal requires nutriment from
pre-existing organisms. Yet this definition fails to apply
to fungi, which resemble primitive animals even in this
respect. So difficult is it to discriminate that the simpler
forms of vegetables have often been classed by naturalists
among animals, and vice versd. Amoeboid movements
have been observed in the bioplasm of vegetable-cells,

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 129

especially in the Volvox, and some have considered it
probable that an organism may live a truly vegetable life-
at one period and a truly animal life at another.

Analogous to amoeboid movements, is the motion of
bioplasmic fluid in the interior of undoubtedly vegetable
cells. This movement is called cydosis, and may be de-
tected under the microscope by the granules or particles
which the current carries with it in the transparent cells
of Chara,Vallisneria, etc., and in the epidermic hairs of
many plants, as Tradescantia, Plantago, etc. (Plate VI,,
Fig. 91).

The bioplasm of plants may be stained with carmine
solution without affecting the cell-wall or other formedi
material.

Cell-wall or Membrane. — Plants, whether simple or
complicated in structure, are but cells or aggregations of
cells. In the simplest vegetables or Protophytes, each cell
lives as it were an independent life, performing every
function; while in the higher plants, as the palm or oak,
the cells undergo special modifications, and serve various
functions subsidiary to the life of the plant as a whole.

Cell-membrane, or the envelope of formed material, was
formerly thought to be composed of two layers, to the
inner one of which the name of primordial utricle was
given, but this is now considered to be but the external
surface of the bioplasm or germinal matter.

The chemical nature of cell-membrane is nearly identi-
cal with starch, being composed of cellulose. The presence
of cellulose may be shown by the blue color which is
produced by applying iodine and sulphuric acid, or the
iodized solution of chloride of zinc.

Endosmose will take place in cell-membrane, allowing
solutions to pass through, as pabulum, and the manner of
this passage may in some instances determine the subse-
quent deposit of formed material. Sometimes actual pores
are left in the membrane, as in Sphagnum (Plate VI, Fig.

130 THE MICROSCOPIST.

92). The walls of vegetable-cells are often thickened by
deposit. If this is in isolated patches, the cells are called
dotted (Plate VI, Fig. 93), and it is sometimes difficult to
distinguish them from porous cells. Many cells have a
spiral fibre (Plate VI, Fig. 94), which appears to have
been detached from the outer membrane. In the seeds of
Collomia, etc., the cell-wall is less consolidated than the
deposit, so that on softening the cells by water, the spiral
fibres suddenly spring out, making a beautiful object for
a half-inch object-glass (Plate VI, Fig. 95).

The tendency of formed material to arrange itself in a
spiral is seen in the endochrome of many of the simpler
plants, as Zygnema, and the cell-wall sometimes tears most
readily in a spiral direction.

If the spiral deposit is broken and coalesces at some of
its turns, it forms an annulus or ring. Some cells show
both rings and spirals.

For the production of a spiral movement or growth,
another force is needed in addition to the centripetal and
centrifugal forces which are necessary for curvilinear mo-
tion. The centripetal point must be carried forward in
space by a progressive force. When we consider that a
spiral form is so frequently seen in morphology, that the
secondary planets move in spirals round their primaries,
and that even in distant nebulae the same law prevails,
we are struck with the unity of plan which is exhibited
throughout the universe, and can scarcely fail to observe
that even a microscopic cell shows the tracings of the same
divine handiwork which swings the stars in their courses.

Sderogen — Ligneous Tissue. — Sometimes the deposit
within the cell-wall is of considerable thickness, and often
in concentric rings, through which a series of passages is
left so that the outer membrane is the only obstacle to
the access of pabulum, as in the stones of fruit, gritty tis-
sue of the pear, etc. (Plate VII, Fig. 96). The nature of
this deposit is similar to cellulose, although often contain-

PLATE VI.

FIG. 91.

FIG. 93.

Dotted cells— pith of Elder.

Fio. 94.

Circulation of fluid in hairs of Tradescantia
Virginica.

Spiral cells : — A, Balsam ; B, c,
Pleurothallis.

FIG. 92.

FIG. 95.

Portion of the leaf of Sphagnum.

Spiral fibres of seed-coat of Collomia.

THE MICB.OSCOPE IN HISTOLOGY AND BOTANY. 131

ing resinous and other matters. Woody fibre or ligneous
tissue is quite similar, save that the cells have become
elongated or fusiform, and when completely filled up with
internal deposit, fulfil no other purpose than that of me-
chanical support (Plate VII, Fig. 97). The woody fibres
of the Coniferce exhibit peculiar markings, which have
been called glandular (Plate VII, Fig. 98). In these the
inner circle represents a deficiency of deposit as in other
porous cells, while the outer circle is the" boundary of a
lenticular cavity between the adjacent cells. This ar-
rangement is so characteristic as to enable us to determine
the tribe to which a minute fragment, even of fossil wood,
belonged.

Spiral Vessels. — If spiral cells are elongated, or coalesce
at their ends, they become vessels, some of which convey
air and some fluid (Plate VII, Fig. 99). As in cells, the
want of continuity in the spiral fibre sometimes produces
rings, when the duct is called annular. In other instances
the spires are still more broken up by the process of growth,
so as to form an irregular network in the duct, which is
then said to be reticulated. A still greater variation in
the deposit produces dotted ducts. Not infrequently we
find all forms in the same bundle of vessels.

Laticiferous Vessels (Plate VII, Fig. 100).— These con-
vey the milky juice or latex of such plants as possess it,
as the Euphorbiacese, india-rubber plant, etc., and differ
from the ducts above described by their branching, so as
to form a network, while ducts are straight and parallel
with each other.

The laticiferous vessels resemble the capillary vessels of
animals, while the spiral ducts remind us of the trachea
of insects.

Siliceous Structures. — The structures of many plants,
especially the epidermis, often become so permeated with
a deposit of silica, that a complete skeleton is left after
the soft vegetable matter is destroyed. The frustules of

132 THE MICROSCOPIST.

Diatoms have in this way been preserved in vast numbers
in the rocky strata of the earth. The markings on these
siliceous shells are so delicate as to be employed as a test
of microscopic power aud definition. In a species of
Equisetum or Dutch rush, silica exists in such abundance
that the stems are sometimes employed by artisans as a
substitute for sand-paper. If such a stem is boiled and
macerated in nitric acid until all the softer parts are de-
stroyed, a cast of pure silica will exhibit not only the
forms of the epidermic cells, but details of the stomata or
pores. The same also is true of the husk of a grain of
wheat, etc., in which even the fibres of the spiral vessels
are silicified. The stellate hairs of the siliceous cuticle
from the leaf of Deutzia scabra forms a beautiful polari-
scope object.

FORMED MATERIAL WITHIN VEGETABLE CELLS.

1. Raphides. — These are crystalline mineral substances,
principally oxalate, citrate, and phosphate of lime. They
occur in all parts of the plant, sometimes in the form of
bundles of delicate needles, sometimes in larger crystals,
and sometimes in stellate or conglomerate form. Mr. E.
Quekett produced such forms artificially by filling the
cells of rice-paper with lime water under an air-pump, aud
then placing the paper in weak solutions of phosphoric or
oxalic acid.

2. Starch. — This performs in plants a similar function
to that of fat in animals, and is a most important ingre-
dient in human food, since two-thirds of mankind subsist
almost exclusively upon it. It is found in the cells of
plants in the form of granules or secondary cells. Each
granule under the microscope shows at one extremity a
circular spot or hilum, around which are a number of
curved lines, supposed to be wrinkles in the cell-membrane.
When starch is boiled in water, this membrane bursts and

PLATE VII.

Gritty tissue— Pear.

Spiral vessels: — A, reticulated; B, old
vessel, with perforations; c, D, spiral
vessels, becoming annular.

FIG. 97.

FIG. 100.

Wood-fibre-flax.

Lactiferous vessels.

FIG. 98.

FIG. 101.

Section of Coniferous Wood in the
direction of the fibres.

Cubical parenchyma, with stellate cells,
from petiole of Nuphar lutea.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 133

the amylaceous matter is dissolved. Iodine stains starch
blue. Starch shows in the polariscope a black cross in
each grain, changing to white as the prism is revolved.

3. Chlorophyll is the green coloring matter of plants.
It is usually seen in the form of granules of bioplasm in
the interior of cells. These green granules yield their
chlorophyll to alcohol and ether. It seems to be neces-
sary to nutrition, since green plants under the stimulus
of light break up carbonic acid into oxygen and carbon,
the latter of which is absorbed.

The red and yellow color of autumn leaves is owing to
the chemical metamorphosis of chlorophyll, as also is the
red color of many of the lower Algse, etc. In the latter
it seems to be in some way connected with the vital pro-
cesses.

4. The coloring matter of flowers is various, and ordinarily
depends on the colored fluid contained in cells subjacent
to the epidermis, although sometimes it is in the form of
solid corpuscles. White patches on leaves, etc., arise from
absence of chlorophyll.

5. Milky juices are true secretions contained in the lati-
ciferous ducts. The juice of the dandelion, caoutchouc
or india-rubber, which is the concrete juice of the Ficus
elastica, and gutta-percha, from Isonandra gutta, are exam-
ples.

6. Fixed oils are found in the cells of active tissues, and
notably in seeds, where they serve to nourish the embryo.
Cocoanut, palm, castor, poppy, and linseed oils are exam-
ples.

7. Volatile oil, sometimes called essential oil, is chiefly
found in glandular cells and hairs of the epidermis.
Many of them yield a resinous substance by evaporation.

8. Camphor is analogous to volatile oil, although solid
at ordinary temperatures. It abounds in the Lauracese.

9. Resin, wax, and tallow are also found in plants. The
bloom of the plum and grape is due to wax.

134 THE MICROSCOPIST.

10. Gum is a viscid secretion. What is called gum
tragacanth, is said to be partially decomposed cell-mem-
brane, and is allied to amyloid matter.

Forms of Vegetable Cells. — From the account given in
the chapter on biology, page 123, it is evident that the
form of cells is quite varied, and often depends on the
amount of pressure from aggregation, yet function also
has much to do in the determination of shape. Thus
while most elongated cells are lengthened in the direction
of plant-growth, in which is least resistance, the medul-
lary rays of Exogenous stems are elongated in a horizon-
tal direction. Some cells are cubical, as in the leaves of
the yellow water-lily, Nuphar lutea (Plate VII, Fig. 101).
Others are stellate, as in the rush (Plate VIII, Fig. 102).
In many tissues are large cavities or air-chambers alto-
gether void of cells, and in leaves such cavities communi-
cate with the external air by means of stomata or pores
(Plate VIII, Fig. 103), which are usually provided with
peculiar cells for contracting or widening the orifice.

The Botanical Arrangement of Plants. — Considered with
reference to their general structure, plants are divided by
botanists into cellular and vascular. The first of these
classes is of greatest interest to the microscopist, as em-
bracing the minuter forms of vegetable life.

The classification and natural grouping of plants is yet
far from being perfect, although microscopic examinations
have largely contributed to an orderly arrangement of the
multitudinous varieties in this field of research. In the
present work we propose only a brief outline of typical
subjects of interest, with the methods of microscopic ex-
amination.

Fungi. — At page 127 it was stated that all living beings
may be grouped in three divisions, fungi, plants, and
animals. Botanists generally class fungi among cellular
flowerless plants. They cannot assimilate inorganic food
as other plants, but live upon the substance of animal or

PLATE VIII.

FIG. 102.

Section of cellular parenchyma of Rush.

Portion of the cuticle of the leaf of the Iris
Germanica, torn from its surface.

FIG. 104.

Cells from the petal of the Geranium
( Pelargonium ).

^Cuticle of leaf of Indian Corn (Zeamais).

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 135

vegetable tissue. They also differ from ordinary vegeta-
bles by the total absence of chlorophyll or its red modifi-
cation. A large number of this strange class are micro-
scopic, and require high powers for their observation.
Recent investigations show that individual fungi are de-
veloped iu very dissimilar modes, and are subject to a
great variety of form, rendering it probable that those
which seem most simple are but imperfectly developed
forms. Amoeboid motions also in the cell-substance of
certain kinds of fungi, and the projection of threads of
bioplasm, show a great resemblance to some of the lower
forms of animal life, as the Rhizopods.

All fungi exhibit two well-defined structures, a myce-
lium or vegetative structure, which is a mass of delicate
filaments or elongated cells ; arid a fruit or reproductive
structure, which varies in different tribes. In Torula, one
or more globular cells are produced at the ends of fila-
ments composed of elongated cells; these globules drop
off and become new mycelia. The " yeast plant," or Torula
cerevisia (Plate IX, Fig. 107), receives its name from its
habitat. Fermentation depends upon its presence, as pu-
trefaction does upon the minute analogous bodies called
Bacteria and Vibriones. Bacteria are minute, moving,
rod-like bodies, sometimes jointed ; and vibriones are
moniliform filaments, having a vibratile or wriggling mo-
tion across the field of view in the microscope. The re-
searches of Madame Luders render it probable that the
germs of fungi develop themselves into these bodies when
sown in water containing animal matter, and into yeast
in a saccharine solution. The universal diffusion of spor-
ules of fungi in the atmosphere readily accounts for their
appearance in such fluids, and Pasteur's experiments are
quite conclusive.

The minute molecules called microzymes, present in va-
rious products of disease, as the vaccine vesicle, fluid of
glanders, etc. ; the minute corpuscles which cause the dis-

136 THE MICROSCOPIST.

ease among silkworms called "pebrine;" etc.; have a
strong analogy in their rapid multiplication to the yeast-
cells.

The sporules of any of the ordinary moulds, as Penidl-
lium, Mucor, or Aspergillus, will develop into yeast-cells
in a moderately warm solution of cane-suga», showing
how differently the same type of bioplasm may develop
under different conditions. The term polymorphism has
been given to this phenomenon. Very many species, and
even genera, so called, may after all be only varieties of
the same kind of organism.

In many morbid conditions of the skin and mucous
membranes, there is not only an alteration or morbid
growth of the part, but a vegetation of fungi. Thrown-
off' scales of epithelium from the mouth and fauces exhibit
fibres of leptothrix, and the false membrane of diphtheria,
as well as the white patches of aphtha or thrush, show
the rnycelia and spores of fungi. The disease in silkworms
called muscardine is due to a fungus, the Botrytis bassiana
(Plate VIII, Fig. 104), whose spores enter and develop in
the air-tubes. The filamentous tufts seen about dead flies
on window-panes, etc., arise from a similar growth of
Achyla. In certain Chinese or Australian caterpillars,
this sort of growth becomes so dense as to give them the
appearance of dried twigs. Even shells and other hard
tissues may become penetrated by fungi. The dry rot in
timber is a form of fungus.

The mildew which attacks the straw of wheat, etc.,
arises from the Puccinia gmminis, whose spores find their
way through the stomata or breathing pores of the epi-
dermis. Rust, and smut, and bunt, originate in varieties
of Uredo. The "vine disease" and the "potato disease,"
as they are called, have similar origin.

Various methods have been proposed to destroy fungi
in growing plants, but it must be remembered that the
function of these organisms is chiefly to remove formed

FIG. 107:

PLATE IX.

FIG. 109.

Germ and Sperm-cells in Achyla.

TO;-M/O Cerevisice, or Yeast-Plant,

FIG. 108.

Development of fungi: A, mycelium; B, hypha; c, conidiophores; D, a magnified branch.

FIG. 110.

Various phases of development of Palmoglaea macrococca.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 137

material in a state of decay, which is more or less com-
plete. The prevalence of atmospheric changes, variations
in light, heat, moisture, and electricity, etc., have much
to do in predisposing vegetable as well as animal tissues to
disease and producing epidemics. The agriculturist, there-
fore, as well as the physician, must discriminate between
those diseased conditions which provide a habitat for
fungi, and the effects produced by the fungi themselves.

Impregnating wood with corrosive sublimate or chlo-
ride of zinc has been used to prevent dry rot in wood, and
soaking seeds in alkaline solutions or sulphate of copper
is said to remove smut and similar fungus spores.

The development of fungi is from spores or conidia.
Plate IX, Fig. 107, represents the Torula vegetating by
the budding of its spores. These buds rapidly fall off and
become independent cells. In other varieties self-division
gives rise to the mycelium, a mass of fibres often inter-
laced so as to form a sort of felt. Some branches of this
mycelium (hyphce) hang down, while others rise above the
surface (conidiophores) and bear conidia, which fall off and
develop into new hyphse (Plate IX, Fig. 108). In the
"blight" of the potato the mycelium is loose, and the
hyphre ramify in the intercellular spaces and give off pro-
jections into the cells of the plant. The conidia germinate
by bursting the sac which contains them, putting forth
cilia, moving awhile, then resting and enveloping them-
selves with membrane and growing into hyphse. In the
autumn, parts of the hyphse assume special functions.
One part develops a spherical mass called oogonium, while
another becomes a smaller mass or antkeridium. When
the first is ripe, it is penetrated by the latter, and the
bioplasms of each are fused together. The antheridium
then decays, while the oogonium grows and becomes an
oospore, in which the bioplasm divides and subdivides.
Next season each segment escapes ciliated, and moves
about till it finds a place to germinate. In Achyla two

138 THE MICROSCOPIST.

sacs are formed, one of which contains "germ-cells," and
the other aniherozoids or "sperm-cells." When both are
ripe the sac opens, and the ciliated antherozoids pass into
the neighboring sac and fertilize its contents (Plate IX,
Fig. 109).

In other fungi the reproductive cells are undistinguisb-
able from the rest, and the coalescence takes place in a
new cell formed by the union of the other two.

Mr. Berkeley divides fungi into six orders, as follows :

1. Hymenomycetes or Agaricoidece (Mushrooms, etc.). —
Mycelium flocuose, inconspicuous, bearing fleshy fruits
which expand so as to expose the hymenium or sporifer-
ous membrane to the air. Spores generally in fours on
short pedicles.

2. Gasteromycetes or Lycoperdoidece (Puff balls, etc.). —
Fruit globular or oval, with convolutions covered by the
hymenium, which bears the spores in fours on distinct
pedicles. The convolutions break up into a pulverulent
or gelatinous mass.

3. Coniomycetes or Uredoidece (Smuts, etc.). — Mycelium
filamentous, parasitic. Microscopic fructification of ses-
sile or stalked spores in groups, sometimes septate.

4. Hyphomycetes or Botrytoidete (Mildews, etc.). — Micro-
scopic. Mycelium filamentous, epiphytic, with erect fila-
ments bearing terminal, free, single, simple, or septate
spores.

5. Ascomycetes or HelvelloidecB (Truffles, etc.). — Myce-
lium inconspicuous. Fruit fleshy, leathery, horny, or ge-
latinous, lobed, or wrarty, with groups of elongated sacs
(asci or theece) in which the spores (generally eight) are
developed.

6. Physomycetes or Mucoroidece (Moulds). — Mycelium
(microscopic) filamentous, bearing stalked sacs containing
numerous minute sporules.

Protophytes, or primitive plants, afford many forms and
groups of great interest to the microscopist as well as to

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 139

the biologist. The plan of the present work permits us
only to indicate a few particulars, the details of which
would form a volume of considerable size.

The Algae are divided into three orders: I. JRhodosper-
mecB or Florida? (Red-spored Algce). Marine plants, with
a leaf-like or filamentous rose-red or purple thallus. II.
Melanosporece or Fucoidece (Dark-spored Algce). Marine.
Thallus leaf-like, shrubby, cord-like, or filamentous, of
olive-green or brown color. III. Chlorosporece or Confer-
voidece (Green-spored Algce). Plants marine or fresh water,
or growing on damp surfaces. Thallus filamentous, rarely
leaf-like, pulverulent, or gelatinous. These have been
subdivided into families, viz. :

I. Rhodospermece. — 1. Rhodomelaceae. 2. Laurenciaceae.
3. Corallinaceae. 4. Delesseriaceae. 5. Rhodymeniaceae.
6. Cryptonemiaceae. 7. Ceramiaceae. 8. Porphyraceae.

II. Melanosporece. — 1. Fucaceae. 2. Dictyotaceae. 3.
Cutleriaceae. 4. Laminariaeeae. 5. Dictyosiphonaceae. 6.
Punctariacese. 7. Sporochnacese. 8. Chordariacese. 9.
Myrionemacese. 10. Ectocarpacese.

III. Chlorosporece. — 1. Lemaneeae. 2. Batrachospermeee.
3. Choetophoraceee. 4. Confervaceae. 5. Zygnemace?e.
6. Q-Cdogoniaceae. 7. Siphonaceae. 8. Oscillatoriaceae. 9.
Nostochacese. 10. Ulvaceaa. 11. Palmellacese. 12. Des-
midiaceae. 13. Diatomaceae. 14. Yolvocineae.

For fuller information, we refer to the Micrographic
Dictionary by Griffith and Henfrey.

In the family of Palmellacece we find the simplest forms
of vegetation in the form of a powdery layer of cells, or a
slimy film, or a membranous frond. The green mould on
damp walls and the red snow of alpine regions are exam-
ples.

In the green slime on damp stones, etc., is found the
Palmoglcea macrococca. The microscope shows it to con-
sist of cells containing chlorophyll, surrounded by a ge-
latinous envelope. These cells multiply by self-division.

140 THE MICROSCOPIST.

Sometimes a conjugation or fusion of cells occurs, and the
product is a spore or primordial cell of a new generation
(Plate IX, Fig. 110). During conjugation oil is produced
in the cells, and the chlorophyll disappears or becomes
brown, and when the spore vegetates, the oil disappears
and green granular matter takes its place. This is analo-
gous to the transformation of starch into oil in the seeds
of the higher plants.

Most of the lower forms of vegetable life pass through
what is called the motile condition, which depends on the
extension of the bioplasm into thread-like filaments, whose
contractions serve to move the cell through the water.
Many of these forms were formerly mistaken for animal-
cules, and the transformation of a portion of green chlo-
rophyll into the red form was represented as an eye. The
multiplication of the "still" cells is by self-division, as in
Palmogl&p,, but after this has been repeated about four
times, the new cells become furnished with cilia and pass
into the "motile" condition, and their multiplication goes
on in different ways, as by binary or quaternary segmen-
tation, or the formation of a compound, mulberry-like
mass, the ciliated individual cells of which, becoming free,
rank as zoospores (Plate X, Fig. 111).

The Volvox is a beautiful example of the composite
motile form of elementary vegetation. It is found in
fresh water, and consists of a hollow pellucid sphere,
studded with green spots, connected together often by
green threads. Each of these spots has two cilia, whose
motions produce a rolling movement of the entire mass.
Within the sphere there are usually from two to twenty
smaller globes, which are set free by the bursting of the
original envelope. Sometimes one of the masses of endo-
chrome enlarges, but instead of undergoing subdivision
becomes a moving mass of bioplasm, which cannot be dis-
tinguished from a true Amoeba or primitive animal cell.

The DesmidiacecB are a family of minute green plants

PLATE X.

FIG. 111.

Various phases of development of Protococcus pluviulis.

Formation of Zoospores in Phyeoseris glgantea(Ulva latissima).

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 141

of great interest. Generally the cells are independent,
but a filament is sometimes formed by binary subdivision.
Their symmetrical shape, and frequently spinous projec-
tions and peculiar movements, render them beautiful ob-
jects. By conjugation a spore-cell or sporangium is pro-
duced, which in some species is spinous, and resembles
certain fossil remains in flint, which have been described
as animalcules under the name of Xanthidia.

The family of Diatomacece affords more occupation to
microscopists than other protophytes. Like the Desmids,
they are simple cells with a firm external coating, but in
Diatoms this coating is so penetrated with silex, that a
cast of the frustule is left after the removal of the organic
matter. Reference has already been made to the number
of these organisms in a fossil state, as well as to their
utility as tests of the defining power of microscopic object-
glasses.

Some species inhabit the sea, and others fresh water.
They are so numerous that scarcely a ditch or cistern is
free from specimens, and they multiply so rapidly as to
actually diminish the depth of channels and block up
harbors. They may be sought for in the slimy masses
attached to rocks and plants in water, in the scum of the
surface, in mud or sand, in guano, in the stomachs of
molluscs, etc., and on sea- weeds.

To separate the shields or siliceous frustules from foreign
matter, either fresh or fossil, they should be washed sev-
eral times in water, and the sediment allowed to subside.
The deposit should then be treated in a test-tube with
hydrochloric acid, sometimes aided by heat. This should
be repeated as often as any effect is produced, and then
the sediment should be boiled in strong nitric acid, and
washed several times in water. They may be mounted
dry or in balsam.

The classification of Diatoms is not yet perfected, but
Muller's type slides, containing from one hundred to five

142 THE MICROSCOPIST.

hundred characteristic forms, is a valuable assistance.
The following table, from the Micrographic Dictionary,
gives an analysis of tribes and genera : Fr. denotes the
frustules in front view; v. the valves; granular striae
means striae resolvable into dots ; and continuous striae
signify costae or canaliculse.

A. Frustules not contained in a Gelatinous Mass or Tube.

TRIBE I. STRIAT.E. — Frustules usually transversely stri-
ate, but neither vittate nor areolate.

t Valves without a Median Nodule.

COHORT 1. EUNOTIE.E. — Fr. arcuate, single, or united
into a straight filament.

1. Epithemia. — Fr. single or binate, with transverse or
slightly radiant striae, some continuous ; no terminal nod-
ules; aquatic and marine.

2. Eunotia. — Fr. single or binate; v. with slightly ra-
diant granular striae and terminal nodules; aquatic.

3. Himantidium,. — Fr. as in Eimotia, but united into a
filament; striae parallel, transverse ; aquatic.

COHORT 2. MERIDE^:. — Fr. cuneate, single, or united
into a curved or spinal band; v. with continuous or gran-
ular striae.

4. Meridian. — Fr. cuneate, united into a spiral band;
striae continuous ; aquatic.

5. Eucampia. — Fr. united into an arched band ; v. punc-
tate; marine.

6. Oncosphenia. — Fr. single, cuneate, uncinate at the
narrow end; striae granular; aquatic.

COHORT 3. FRAGILLARIEJE. — Fr. quadrilateral, single, or
united into a filament or chain ; v. with continuous or
granular striae.

7. Diatom a. — Fr. linear or rectangular, united by the

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 143

angles so as to form a zigzag chain; striae continuous;
aquatic and marine.

8. Asterionella.—^v. adherent by adjacent angles into
a. star-like filament; v. inflated at one or both ends;
aquatic.

9. Fragillaria. — Fr. linear, united into a straight, close
filament ; striae granular, faint ; aquatic and marine.

10. Denticula. — Fr. linear, simple, or binate, rarely more
united ; striae continuous ; aquatic.

11. Odontidium. — As Denticula, but fr. forming a close
filament; aquatic and marine.

COHORT 4. MELOSIREJE. — Fr. cylindrical, disk-shaped or
globose; v. punctate, or often with radiate continuous
or granular striae.

12. Cyclotella. — Fr. disk-shaped, mostly solitary; v.
with radiate marginal striae ; aquatic.

13. Melosira. — Fr. cylindrical or spherical, united into
a filament; v. punctate, or with marginal radiate granu-
lar striae ; aquatic and marine.

14. Podosira. — Fr. united in small numbers, cylindrical
or spherical, fixed by a terminal stalk; v. hemispherical,
punctate; marine.

15. Mastogonia. — Fr. single; v. unequal, angular, mam-
miform, circular at base, without umbilical processes ;
angles radiating; fossil.

16. Pododiscus. — Fr. single or united, with a marginal
stalk ; v. circular, convex.

17. Pyxidicula. — Fr. single or binate, free or sessile;
v. convex ; aquatic and marine.

18. Stephanodiscus. — Fr. single, disk-shaped; v. circu-
lar, equal, punctate, or striate, with a fringe of minute
marginal teeth ; aquatic.

19. Stephanogonia. — Fr. as in Mastogonia, but ends of
valves truncate, angular, and spinous; fossil.

20. Hercotheca. — Fr. single, turgid laterally; v. with
marginal free setae.

144 THE MICROSCOPIST.

21. Goniothedum. — Fr. single, constricted in the middle,
suddenly attenuate and truncate at the ends (hence appear-
ing angular).

COHORT 5. SURIRELLE.E. — Fr. single or binate, quadri-
lateral, oval, or saddle-shaped, sometimes constricted in
the middle; v. with transverse or radiating continuous
or granular striae, interrupted in the middle, or with one
or more longitudinal rows of puncta; often keeled.

22. Badllaria. — Fr. prismatic, straight, at first forming
a filament ; v. with a median longitudinal row of puncta ;
marine.

23. Campylodiscus. — Fr. single, free, disk-shaped; v.
curved or twisted (saddle-shaped); aquatic and marine.

24. Doryphora. — Fr. single, stalked ; v. lanceolate or
elliptical, with transverse granular striae.

25. Podocystis. — Fr. attached, sessile; v. with a median
line, transverse continuous, and intermediate granular
striae.

26. Nitzschia. — Fr. free, single, compressed, usually elon-
gate, straight, curved, or sigmoid, with a not-median
keel, and one or more longitudinal rows of puncta;
aquatic and marine.

27. Sphinctocystis(Cymatopleura). — Fr. free, single, linear,
with undulate margins ; v. oblong or elliptical, sometimes
constricted in the middle; aquatic.

28. Surirella. — Fr. free, single, ovate, elliptical, oblong,
cuneate, or broadly linear ; v. with a longitudinal median
line or clear space, margins winged, and with transverse
or slightly radiating continuous stride ; aquatic and marine.

29. Synedra. — Fr. prismatic, rectangular, or curved ; at
first attached to a gelatinous-lobed cushion, often becom-
ing free; v. linear or lanceolate, usually with a median
pseudo-nodule and longitudinal line ; aquatic and marine.

30. Tryblionella. — Fr. free, linear, or elliptical ; v. plane,
with a median line, transverse striae, and submarginal or
obsolete alse ; aquatic and marine.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 145

•

31. Raphoneis.—Doryphora without a stalk.

COHORT 6. AMPHIPLEURE^E. — Fr. free, single, straight,
or slightly sigrnoid ; v. lanceolate, or linear-lanceolate,
with a median longitudinal line.

32. Amphipleura. — Characters as above.

ft Valves with a Median Nodule.

COHORT 7. COCCONEID^:. — Fr. straight or bent, attached:
by the end or side; v. elliptical, equilateral.

33. Cocconeis. — Fr. single, compressed, adnate; v. ellip-
tical, one of them with a median line.

COHORT 8. ACHNANTHE.E. — Fr. compressed, single, or
rarely united into a straight filament, curved, attached
by a stalk at one angle; uppermost v. with a longitudinal
median line, lower v. the same, and a stauros or transverse
line; marine.

35. Achnanthidium. — Fr. those of Achnanthes, but free ;
aquatic.

36. Cymbosim. — Fr. as Achnanthes, solitary or binate,
stipitate, and attached end to end ; marine.

COHORT 9. CYMBELLE^E. — Fr. straight or curved, free or
stalked at the end ; v. inequilateral, not sigmoid.

37. Cymbella. — Fr. free, solitary; v. navicular, with a
subcentral and two terminal nodules, and a submedian
longitudinal line ; aquatic.

38. Cocconema. — Fr. as Cymbella, but stalked; aquatic.
COHORT 10. GOMPHONEME.E. — Fr. wedge-shaped, straight,

free, or stalked ; v. equilateral.

39. Gomphonema. — Fr. single or binate, wedge-shaped,
attached by their ends to a stalk; v. with a median line,
and a median and terminal nodules; aquatic.

40. Sphenella. — Fr. free, solitary, wedge-shaped, invo-
lute; aquatic.

10

146 THE MICROSCOPIST.

41. Sphenosira. — Fr. united into a straight filament; v.
wedge-shaped, at one end rounded, suddenly contracted
and produced; aquatic.

COHORT 11. NAVICULE^;.— Fr. free, straight; v. equilat-
eral, or sometimes sigmoid.

42. Navicula. — Fr. single, free, straight ; v. oblong, lan-
ceolate, or elliptical, with a median line, a central and two
terminal nodules, and transversely or slightly radiant lines
resolvable into dots ; aquatic, marine, and fossil.

43. Gyrosigma (Pleurosigma). — Fr. as Navicula, but v.
sigmoid ; aquatic and marine.

44. Pinnularia. — Fr. as Navicula, but transverse lines
continuous ; aquatic and marine.

45. Stauroneis. — Fr. as Navicula, but the median line
replaced by a stauros; aquatic and marine.

46. Diadesmis. — Fr. as Navicula, united into a straight
filament; aquatic.

47. Amphiprora. — Fr. free, solitary, or in pairs, con-
stricted in the middle; v. with a median keel, and a
median and terminal nodules, often twisted ; marine.

48. Amphora. — Fr. plano-convex, elliptical, oval or ob-
long, solitary, free or adnate, with a marginal line, and a
nodule or stauros on the flat side ; aquatic and marine.

TRIBE II. VITIATE. — Fr. with vittee.

t Valves without a Median Nodule.

COHORT 12. LICMOPHORE.E. — Fr. cuneate; vittfe arched.

49. Licmophora.- — Fr. cuneate, rounded at the broad
end, radiating from a branched stalk; vittse curved (by
inflection of upper margins of valves) ; marine.

50. Podosphenia.—Fr. as Licmophora, but single or in
pairs, sessile on a thick but little branched pedicle; ma-
rine.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 147

51. Rhipidophora. — Fr. as Licmophora, single or in pairs,
on a branched stipes ; marine.

52. Climacosphenia. — Fr. cuneate, rounded at broad end,
divided into loculi by transverse septse or vittse ; marine.

COHORT 13. STRIATELLE^;. — Fr. tabular or filamentous;
vittee straight (not arched).

53. Striatella. — Fr. compound, stalked at one angle;
vittse longitudinal and continuous ; v. elliptic-lanceolate,
not striated ; marine.

54. Rhabdonema. — Fr. as Striatella, but vittse inter-
rupted ; v. with transverse granular strise ; marine.

55. Tetracydus. — Fr. compound, filamentous ; vittee al-
ternate, interrupted ; v. inflated at the middle ; striae trans-
verse, continuous ; aquatic.

56. Tabellaria. — Fr. united into a filament, subsequently
breaking up into a zigzag chain ; vittoe interrupted, alter-
nate ; v. inflated at middle and ends ; aquatic.

57. Pleurodesmium. — Fr. tabular, united into a filament,
and with a transverse median hyaline band ; marine.

58. Hyalosira. — Fr. tabular, fixed by a stalk at one
angle ; vittse alternate, interrupted, bifurcate at the end ;
marine. .

59. Anaulus. — Fr. rectangular, single, compressed, with
lateral inflections, giving the valves a ladder-like appear-
ance ; marine.

60. Biblarium. — Fr. as Tetracydus, but single ; fossil.

61. Terpsinoe. — Fr. tabular, obsoletely stalked, subse-
quently connected by isthmi ; vittse transverse, short, in-
terrupted, and capitate ; aquatic and marine.

62. Stylobiblium. — Fr. compound ; v. circular, sculptured
with continuous strise ; fossil.

ft With a Median apparent (pseudo) Nodule.
63. Grrammatophora. — Fr. at first adnate, afterwards

148 THE MICROSCOPIST.

forming a zigzag chain ; vittse two, longitudinal, inter-
rupted, and more or less figured ; marine.

TRIBE III. AREOLAM. — Valves circular, with cell-like
(areolar) markings, visible by ordinary illumination.

SUB-TRIBE 1. DISCIFORMES. — Valves alike, without ap-
pendages or processes.

COHORT 14. COSCINODISCE.E. — Valves circular.

64. Actinocydus. — Fr. solitary; v. circular, undulate,
the raised portions like rays or bands radiating from the
centre, which is free from markings ; marine and fossil.

65. Actinoptychm. — Fr. as Actinocydus, but radiating
internal septae, as well as rays.

66. Coscinodiscus . — Fr. single ; v. circular, areolar all
over ; marine and fossil.

67. Aracknoidiscus. — Fr. single ; v. circular, not undu-
late, with concentric and radiating lines, and intermediate
areola absent from the centre (pseudo-nodule); marine
and fossil.

68. Asterolampra. — Fr. single ; v. circular, finely areolar,
except in the centre and at equidistant clear marginal rays
radiating from the centre, which is traversed by radiating
dark lines (septa), alternating with the marginal rays ;
fossil.

69. Aster omphalos. — As Asterolampra, but two of the
central dark lines parallel, and the corresponding mar-
ginal ray obliterated ; fossil.

70. Halionyx. — Fr. single ; v. circular, without septa,
with rays not reaching the centre, and with intermediate
shorter rays ; between the rays transverse areolar lines ;
fossil.

71. Odontodiscus. — Fr. single, lenticular ; v. covered
with puncta (areolee), arranged in radiating rows on ex-
centrically curved lines, and with erect marginal teeth ;
fossil.

72. Omphalopelta. — As Actinoptychus, but upper part of
margin of valves with a few erect spines ; fossil.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 149

73. Symbolophora. — Fr. single, disk-shaped ; v. with in-
complete septa radiating from the solid angular umbili-
cus, and intermediate bundles of radiating lines ; marine
and fossil.

74. Systephania. — Fr. single ; v. circular, areolar, with-
out rays or septa, with a crown of spines or an erect
membrane on the outer surface of each valve ; fossil.

COHORT 15. ANGULIFERA. — Valves angular.

75. Amphitetras. — Fr. at first united, afterwards sepa-
rating into a zigzag chain, rectangular; v. rectangular,
the angles often produced ; marine.

76. Amphipentras. — Fr. solitary ; v. pentangular ; fossil.

77. Lithodesmium. — Fr. united into a straight filament ;
v. triangular, one side plane, the others undulate ; marine.

TRIBE IY. APPENDICULAT^E. — Valves with processes or
appendages, or with the angles produced or inflated.
COHORT 16. EUPODISCEJE. — Fr. disk-shaped ; v. circular.

78. Eapodiscus. — Fr. single, disk-shaped ; v. circular,
with tubular or horn-like processes on the surface ; aquatic
and marine.

79. Auliscus. — As Eupodiscus^but processes obtuse and
more solid ; fossil.

80. Insilella. — Fr. single, fusiform ; v. equal, with a
median turgid ring between them ; marine.

COHORT 17. BIDDULPHIE^E. — Fr. flattened; v. elliptical
or suborbicular.

81. Biddidphia. — Fr. rectangular, more or less united
into a continuous or zigzag filament ; the angles inflated
or produced into horns ; v. convex, centre usually spinous ;
marine.

82. Isthmia. — Fr. rhomboidal or trapezoidal, cohering
by one angle ; angles produced ; marine.

83. Chcetoceros. — Fr. compressed ; v. equal, with a long
spine or filament on each side ; marine.

150 THE MICROSCOPIST.

84. Rhizoselenia. — Fr. elongate, subcylindrical, marked
with transverse or spiral lines, ends oblique or conical,
and with one or more terminal bristles ; marine.

85. Hemiaulus. — Fr. single, compressed, rectangular;
angles produced into tubular direct processes, those on
one valve longer than on the other ; fossil.

86. Syringidium. — Fr. single, terete, acuminate at one
end, two-horned at the other ; marine.

87. Periptera.—Fr. single, compressed ; v. unequal, one
simply turgid, the other with marginal wings or spines ;
fossil.

88. Didadia. — Fr. single; v. unequal, one turgid and
simple, the other two-horned ; fossil.

COHORT 18. ANGULAT^E. — Valves angular.

89. Triceratium. — Fr. free ; v. triangular, each angle
with a minute tooth or horn ; marine.

90. Syndendrium. — Fr. single, subquadrangular ; v. un-
equal, slightly turgid, one smooth, the other with numer-
ous median spines, or little horns branched at the ends.

B. Frustules enveloped in a mass of Gelatin, or contained in
Gelatinous Tubes, forming a Frond.

91. Mastogloia. — Frond mammilate ; fr.Jike Navicula,
but hoops with loculi ; aquatic and marine.

92. Dickieia: — Frond leaf-like ; fr. like Namcula or
Stamoneis ; marine.

93. Berkeley^. — Frond rounded at base, filamentous at
circumference ; fr. navicular ; marine.

94. Homoeocladia. — Frond sparingly divided, filiform ;
fr. like Nitzschia ; marine.

95. Colletonema. — Frond filamentous, filaments not
branched ; fr. like Namcula or Gyrosigma ; aquatic.

96. Schizonema. — Frond filamentous, branched ; fr. like
Namcula; marine.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 151

97. Encyonema. — Frond filamentous, but little branched ;
f'r. like Cymbella ; aquatic.

98. Syncydia. — Fr. those of Cymbella, united in circular
bands, immersed in an amorphous gelatinous frond ; ma-
rine.

99. Frustulia. — Fr. as Navicula, irregularly scattered
through an amorphous gelatinous mass ; aquatic.

100. Micromega. — Fr. as Navicula, arranged in rows in
gelatinous tubes, or surrounded by fibres, these being in-
closed in a filiform branched frond ; marine.

The family of Nostochince is allied to the Palmellacece.
It consists of beaded filaments suspended in a gelatinous
frond. The gelatinous masses of Nostoc often appear quite
suddenly in damp places, and have been called "fallen
stars." They attracted the notice of the alchemists, and
enter into many of their recipes for the transmutation of
metals. What have been termed showers of flesh or of
blood, originated in all probability in the rapid develop-
ment of similar masses. Many botanists regard them as
the " gonidia " of Collema and other lichens.

The Oscillatoria, so called from the singular oscillatory
motion of their filaments, consist also of cells which mul-
tiply in a longitudinal direction by self-division. The
Ulvacece, to which the grass-green sea-weeds belong, in-
crease in breadth as well as length by the subdivision of
cells, so as to produce a leaf-like expansion (Plate X, Fig.
112). An illustration of the simpler forms of reproduction
in Protophytes is seen in Zygnema,&Q called from the sin-
gular manner in which the filaments are yoked together
in pairs. In an early stage of growth, while multiplica-
tion of cells proceeds by subdivision, the endochrome is
generally diffused, but about the time of conjugation it
arranges itself usually into a spiral. Adjacent cells put
forth protuberances, which unite and form a free passage
between them, and the endochrome of one cell passes over

152 THE MICROSCOPIST.

into the other and forms the spore. In Sphoeroplea the
endochrome of the " oospore " breaks up into segments,
which escape as " microgonidia." Each of these have
two vibratile filaments, which elongate so as to become
fusiform, and at the same time change from red to green.
Losing their motile power they become filaments, in which
the endochrome, by the multiplication of vacuoles, be-
comes frothy. After a time the particles of endochrome
assume1 a globular or ovoid shape, and openings occur in
the cell- wall. In other filaments the endochrome is con-
verted into antherozoids, each of which is furnished with
two filaments, by means of which they swim about and
enter the openings of the spore-cells, in which they seem
to dissolve away. The contents of the spore-cell then
becomes invested with a membranous envelope ; the color
changes from green to red ; a second investment is formed
within the first, which extends itself into stellate projec-
tions. When set free the mass is a true oospore, and
ready to repeat the process above described. In GEdogo-
nium the antherozoids are developed in a body called an
" androspore," which is set free from a germ-cell, and
which being furnished with cilia resembles an ordinary
zoospore. This androspore attaches itself to the outer
surface of a germ-cell, a sort of lid drops from its free
extremity, which sets free its contained antherozoids.
These enter an aperture formed in the cell- wall of the
oospore, and fertilize the contained mass by blending
with it.

Examination of the Higher Cryptogamia. — It would en-
large this volume far beyond its proposed limits to refer
to the particular instances of form or function which the
microscope reveals to the systematic botanist or physiolo-
gist, nor is this necessary, since well-written treatises on
structural botany are quite available. We content our-
selves, therefore, in the remainder of this chapter, with
pointing out the methods of examination by which the

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 153

views of other observers may be verified, or additions
made to our knowledge of vegetable life.

The lower forms of algae and fungi, to which we have
already referred, need scarcely any preparation, save the
disentanglement of twisted threads under the simple mi-
croscope, or a gentle teasing with needles, or rinsing with
water. The solution of iodine, and of iodine and sulphuric
acid, will suffice to exhibit the nature of the cell-wall and
cell-contents. In more highly developed plants it will be
necessary to take thin sections from different parts, a'nd
in different but definite directions. These sections may
be made by hand, or between pieces of pith or cork by
means of a section cutter. In some instances some of the
methods of staining will also be useful. Dr. Hunt, of
Philadelphia, has proposed a plan of staining which is
well adapted to all vegetable tissues. He first soaks the
part or section in strong alcohol to dissolve the chloro-
phyll, then bleaches it in a solution of chlorinated soda.
It is then placed in a solution of alum, and afterwards in
one of extract of logwood. By transferring it to weak
alcohol and afterwards to stronger, it is deprived of its
water, and after being made transparent with oil of cloves,
it is ready for mounting in balsam or dammar varnish.
Care must be taken to wash it well after each of the
preliminary steps before staining.

In the higher algse, the layers of cells assume various
sizes and shapes, and the nature of their fructification is
of great interest. Sections may be made of the " recep-
tacles " at the extremities of the fronds, which contain
filaments, whose contents become antherozoids. The pear-
shaped sporangia in the receptacles subdivide into clusters
of eight cells, called octospores, which are liberated from
their envelopes before fertilization.

The red sea-\veeds, or Rhodospermece, afford many beau-
tiful forms for the microscope. The " tetraspores " are
imbedded in the fronds.

THE MICROSCOPIST.

In lichens, the apothecia form projections from the thal-
lus, or general expansion produced by cell-division. A
vertical section shows them to contain asci or spore-cases
amid straight filaments, or elongated cells called para-
physes.

The fronds of Hepaticce or liverworts bear stalks with
shield-like disks, which carry antheridia, and others with
radiating bodies bearing archegonia, which afterwards
give place to the sporangia or spore-cases. The spores
are associated with elaters, or elastic spiral fibres, which
suddenly extend themselves and disperse the spores.

The Characece are often inc rusted with carbonate of
lime, which may be removed with dilute sulphuric acid.
The motion of the bioplasm in the cells of the stem is
often well seen. The cells in which the spiral filaments
or antheridia are developed, are strung together like a
row of pearls. The position and construction of the spores
also should be examined, as well as the mode of growth
in the plant by division of the terminal cell (Plate XI,
Fig. 113).

Stems of mosses and liverworts should be examined by
means of transverse and longitudinal sections. Similar
sections through the half-ripe fruit of a moss will show
the construction of the fruit, the peristome, the calyptra,
etc. The ripe spores may be variously examined dry, in
water, in oil of lemons, and in strong sulphuric acid. The
capsules or urns of mosses are not now regarded as their
fructification, but its product.

The true antheridia and pistillidia are found among the
bases of the leaves, close to the axis. The fertilized " em-
bryo-cell " becomes gradually developed by cell-division
into a conical body or spore-capsule, elevated on a stalk.
The peristome, or toothed fringe, seen around the mouth
of the urn when the calyptra or hood, and operculum or
lid, are removed, furnishes a beautiful object for the bi-
nocular microscope.

PLATE XI.

FIG. 113.

Antheridia of Chara fragilix:— A, antheridium or "globule" developed at the base of pistillidinm or
"nucule;" B, nucule enlarged, globule laid open by the separation of its vaivos; c, one of the valves,

with its group of antheridial filaments, each composed of a linear series of cells, within every ono of
which an antherozoid is formed ; in D, K, and F, the successive stages of this formation are seen ; and at
G is shown the escape of the mature autherozoids, 11. (From Carpenter.)

Development of Prothalium of Plerix serruJnta: — A, spore set free from the theca; B, spore beginning
to germinate, putting forth the tubular prolongation n, from the principal cell b; c, fi-st formed linear
series of cells ; D, prothaliinm taking the form of a leaf-like expansion ; a first and b second radical
fibre ; c, </, the two lobps. and e the indentation between them ; /, /', first-formed part of the prothallium ;
g, external coat of the original spore ; A, A, aiitheridia. (From Carpenter.)

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 155

The Sphagnum, or bog-moss, has large and elongated
leaf-cells, with loosely-coiled spiral fibres, and their mem-
branous walls have large apertures. Their spores are of
two kinds, and when germinating in water, produce a long
filament with root-fibres at the lower end and a nodule
at the upper, from which the young plant is formed. If
grown on wet peat, instead of a filament there is evolved
a lobed foliaceous protkattitttn, resembling the frond of
liverworts.

In ferns the structure approximates to true flowering
plants, while the reproductive organs are those of crypto-
gamia. Thin sections of the stem, cut obliquely, show
the scalariform or ladder-like vessels. The fructification
is usually found on the under side of the frond in isolated
spots called sori. Each of these contains a number of cap-
sules or thecce, and each capsule is surrounded by an an-
nidus or ring, whose elasticity opens the capsule when
ripe and permits the spores to escape. The spores are
somewhat angular, and when vegetating give rise to a
leaf-like expansion called a prothallium. In this the an-
theridia and archegonia, which represent the true flower
of higher plants, are developed. The ciliated anthero-
zoids from the antheridia penetrate the cavity of the
archegonium and fertilize the u germ-cell," which subdi-
vides and becomes a young fern, while the prothallium,
having discharged the functions of a nurse, withers away
(Plate XI, Fig. 114). The group of JSquisetacece or horse-
tails is interesting from the siliceous skeletons of the epi-
dermis, already referred to, page 131, as well as for the
elastic filaments attached to their spores.

EXAMINATION OF HIGHER PLANTS.

The elementary tissues described in the beginning of
this chapter are chiefly characteristic of phanerogamic
plants, yet some additional particulars remain to be no-

156 THE MICROSCOPIST.

ticed in connection with, the axis or stem, the leaves,
flowers, and fruit.

1. The Stem. — The arrangement of fibre-vascular bun-
dles, i. e.. woody fibres and ducts, differs widely in the
two botanical divisions of Monocotyledons and Dicotyle-
dons. In the first the growth is endogenous, and a section
exhibits the bundles of fibres and ducts disposed without
regularity in the mass of cellular tissue which forms the
basis of the fabric. In the second, or exogenous stems,
the fibro-vascular bundles are wedge-shaped, and inter-
posed between the bark and the pith, being kept apart by
plates of cellular tissue, called medullary rays, proceeding
from the pith.

The course of the vascular bundles in monocotyledons
should be carefully followed, either by maceration or
minute dissection. In the dicotyledonous stem, sections
must be made in three directions, transversely, longitu-
dinally across the diameter, and at a tangent from the
bundles of fibres. The section-cutter, described page 63,
will be serviceable, although a sharp razor or scalpel may
serve. The size, form, and contents of the pith-cells
should be noticed, and their transition to wood-cells.
The arrangement of the medullary rays, of the wood-cells,
and of the ducts must also be observed, and in the Coni-
ferae the position of the pits. The cambium layer, between
the bark and wood, may have its cells rendered more
transparent by weak alkalies, and their contents tested
with iodine solution. The course and construction of
laticiferous vessels in the bark, when present, and of the
cork-cells of the tuberous layer, may be noted.

Fossil woods may be cut with a watch-spring saw, and
ground on a hone like bone or teeth. Sometimes it is
best to break off small lamella by careful strokes with a
steel hammer. It is sometimes useful to digest fossil
wood in a solution of carbonate of soda for several days
before cutting.

THE MICROSCOPE IN HISTOLOGY AND BOTANY. 157

2. Leaves. — These should be examined by thin longitu-
dinal and transverse sections. The epidermis of both sides
should be detached, and the position and arrangement of
the stomata observed (Plate VII, Fig. 100). The hairs
of the epidermis, the arrangement of the parenchyma, and
the distribution of the vascular bundles in the form of
nerves, are also of importance.

3. Flowers. — For ascertaining the number and position
of the parts of the flower, transverse sections at different
heights through an unopened bud may be taken, together
with a longitudinal section exactly through the middle.
The general structure of sepals and petals corresponds with
that of leaves, but there are some peculiarities. Thus the
cells of the petal of the geranium exhibit when deprived
of epidermis, dried and mounted in balsam, a peculiar
mammillated appearance with radiating hairs (Plate VIII,
Fig. 102). Anthers and pollen grains are also interesting
microscopic objects. The protrusion of the inner mem-
brane through the exterior pores in pollen may be stimu-
lated by moistening with water, dilute acid, etc. The
penetration of the pollen tubes through the tissue of the
style may be traced by sections or careful dissection. The
heartsease, viola tricolor, and the black and red currant,
ribes nigrum and rubrum, have been recommended for this
purpose.

4. Seeds. — The reticulations or markings on various
kinds of seeds render them frequent objects for observa-
tion with the binocular microscope. Adulterations may
also be detected in this way, as well as imperfect seeds in
any sample, a subject of much importance to the practical
farmer.

153 THE MICROSCOPIST.

CHAPTER XL

THE MICROSCOPE IN ZOOLOGY.

WE have already seen that both animal and vegetable
structures originate in a jelly-like mass or cell, and that
in the simple forms it is difficult, if not impossible, to
determine whether the object is an animal or a vegetable.
The mode of alimentation, and not structure, is our only
guide in the discrimination of the Protozoa or elementary
animal forms from Protophytes or simple vegetables.

It has been proposed by Professor Heeckel to revive the
idea of a kingdom of nature intermediate between plants
and animals, but it does not appear that any gain to sci-
ence would result from such an arrangement.

I. MONERA. — The simplest types of Protozoa are mere
particles of living jelly (Plate XII, Fig. 115), yet they
possess the power of contraction and extension, and of
absorbing alimentary material into their own substance
for its nutrition. The Bathybius^ from the "globigerina
mud," referred to on page 9d, seems to have been an in-
definite expansion of such protoplasm or bioplasm.

II. RHIZOPODS. — This term (meaning root-footed) is ap-
plied to such masses of sareode or bioplasm as extend long
processes, called pseudopodia, as prehensile or locomotive
organs (Plate XII, Fig. 116). The Rhizopods are either
indefinitely organized jelly, like Monera, or attain a cov-
ering or envelope of membrane called ectosarc, while the
thin contents are termed endosarc. The first order of
Rhizopods, Reticularia, consist of indefinite extensions of
freely branching and mutually coalescing bioplasm. The
second order, Radidaria, have rod-like radiating exten-
sions of the ectosarc, which do not coalesce. The order
Lobosa are lobose extensions of the body itself, as in the

THE MICROSCOPE IN ZOOLOGY. 159

Amoeba prince ps already described. Some of this latter
order, as Arcella and Difflugia^&re testaceous. In Arcella
the test is a horny membrane, analogous to the chitine
which hardens the integuments of insects. In Difflugia
the test is made up of minute particles of gravel, shell,
etc., cemented together. From the opening the amosboid
body puts forth its pseudopodia (Plate XII, Fig. 117).
Connected with Rhizopods are three remarkable series of
forms, generally marine, and distinguished by skeletons
of greater or less density, which afford many objects of
interest to the microscopist. These are the Foraminifera^
the Polycystina, and the Sponges or Porifera. The shells
of the Foraminifera are calcareous, and those of Polycys-
tina siliceous ; both are perforated with numerous aper-
tures, which in Polycystina are often large. We have
previously referred to these forms as occurring in a fossil
state.

Some Foraminifera have porcellanous, and others vitre-
ous or hyaline shells, usually many-chambered, and of every
shape between rectilinear and spinal. Most of them are
microscopic, but some are of considerable size, as the Or-
bitolites, which are found in tertiary limestones in Malabar.
The Nummulitic limestone, which extends over large areas
of both hemispheres, and of which the pyramids of Egypt
are built, is composed of the remains of the genus Num-
mulina; and the Eozoon Canadense has been shown by
Drs. Dawson and Carpenter to belong to the Foramini-
feral type.

In some Foraminifera the true shell is replaced by a
sandy envelope, whose particles are often cemented by
phosphate of iron. Dr. Carpenter, whose researches have
largely extended our knowledge of this group, pertinently
remarks that "there is nothing more wonderful in nature
than the building up of these elaborate and symmetrical
structures by mere jelly specks, presenting no trace what-
ever of that definite 'organization' which we are accus-

160 THE MICROSCOPIST.

tomed to regard as necessary to the manifestations of
conscious life."*

The Polycystina, like the Foraminifera, are beautiful
objects for the binocular microscope, with the black-
ground illumination by the Webster condenser, the spot-
lens, or the paraboloid.

The Porifera or sponges begin life as solitary Amoeba,
and amid aggregations formed by their multiplication,
the characteristic spicules of sponge-structure make their
appearance. In one group, the skeleton is a siliceous
framework of great beauty. In Hyalonema, the silica is
in bundles of long threads like spun glass. Sometimes
sponge spicules are needle-like, straight or curved, pointed
at one or both ends ; sometimes with a head like a pin,
furnished with hooks, or variously stellate. Dr. Carpen-
ter thinks it probable that each spicule was originally a
segment of sarcode, which has undergone either calcifica-
tion or silicification (Plate XII, Fig. 118).

III. INFUSORIAL ANIMALCULES. — From the earliest his-
tory of the microscope, the minute animals found in vari-
ous infusions or in stagnant pools, etc., have attracted
attention. We owe to Professor Ehrenberg the first sci-
entific arrangement of this class, and although more ex-
tended observations have changed his classification, yet
many of his views are still accepted by the most recent
investigators. Ehrenberg divided this class into two
groups, which represent very different grades of organi-
zation. The first he called Polygastrica (many-stomached)
from a view of their structure, which subsequent examin-
ations have not confirmed. The other group is that of
JRotifera or Rotatoria, a form of animal life which is most
appropriately classed among worms. The term Infusoria
is now applied to those forms which Professor Ehrenberg

* The Microscope and its Revelations, by W. B. Carpenter, M.D.,
LL.D., etc.

PLATE XII.

FIG. 115.

FIG. 116.

Monera (Amoeba).

A, Difflugiaproteiformis; -B,Diffl,ugiaoblonga; c,Arcella
acuminata; D, Arcella dentata.

Gromiaoviformis^iih its pseudopodia extended.

FIG. 118.

Structure of Grantia compressa: B, small portion highly magnified.

THE MICROSCOPE IN ZOOLOGY. 161

called polygastric animalcules. . Yet a large section de-
scribed by him in this connection, including the Desmidi-
acece, Diatomacece, Volvocinece, and other protophytes, have
been transferred by naturalists to the vegetable kingdom.

The bodies of the Infusoria consist of sarcode or bio-
plasm, having an outer layer of firmer consistence. Some-
times the integument is hardened on one side so as to form
a shield, and in other cases it is so prolonged and doubled
upon itself as to form a sheath or cell, within which the
animalcule lies. The form of the body is more definite
than that of Amoeba, so as to be characteristic of species.
It may be oblong, oval, or round ; and some kinds, as
Vorticella, are attached to a footstalk, which has the power
of contracting in a spiral coil. ~No distinct muscular
structure can be detected in the Infusoria, yet the general
substance of the body is contractile. In most species
short hair-like filaments or cilia project from the surface,
sometimes arranged in one or more rows round the mouth,
and moving to all appearance under the influence of voli-
tion. In others there are one or two flagelliform filaments,
or long anterior cilia with vibratile ends. Others, again,
have setse or bristles, which assist in locomotion. The
motions of some are slow, and of others quite rapid.

The interior of the sarcode body exhibit certain round-
ish spots, sometimes containing Diatoms or other foreign
substances. They have been called gastric vesicles, cells,
spaces, or sacculi. They are only visible from their con-
tents, and seem to be mere spaces without a living mem-
brane. If a little indigo or carmine is diffused in the
water which contains the Infusoria, the cavities will soon
be filled and become distinct. If watched carefully they
will appear to move round the body of the animal, and as
the pigment escapes at some part of the surface, the spots
will disappear. Ehrenberg regarded these spots as so
many stomachs arranged about a common duct, but the
common opinion at present regards them as temporary

11

162 THE MICROSCOPIST.

digestive sacs made by the inclosure of food by the soft
bioplasm.

In addition to the "vacuoles" described, contractile
vesicles are seen which contract and dilate rhythmically,
and do not change their position. They have been con-
sidered to serve for respiration.

Most of the Infusoria multiply by self-division (Plate
XIII, Fig. 119), and at certain times undergo an encyst-
ing process, much resembling the " still " condition of Pro-
tophytes, and like that serving for preservation under
circumstances which are unfavorable to ordinary vital
activity. The gemmules or progeny which result from
the bursting of the cyst do not always resemble the parent
in form. The recent researches of Drs. Dallinger and
Drysdale have shown considerable variety in the life his-
tory of the Infusoria. In some instances the product of
the encysting process was not a mass of granules, but an
aggregation of minute germinal particles not more than
sWotJoth °f an incn in diameter, and capable of resisting
heat, either by boiling or by dry heating up to 300° F.

The observations of M. Balbiani show that in many of
the Infusoria, male and female organs are combined in
the same individual, but that a congress of two is neces-
sary for the impregnation of the ova, those of each being
fertilized by the spermatozoa of the other.

There is also a curious tribe of suctorial animalcules
called Acinetce, which put forth tubular prolongations
which penetrate the bodies of other species and grow in
their interior as parasites.

The systematic arrangement of the Infusoria is yet
unsettled. Ehrenberg's families, excluding those now
placed among Algse or Rhizopods, are as follows :

THE MICROSCOPE IN ZOOLOGY. 163

A. Intestinal tube absent.

Body variable, without cilia.

Carapace absent, . _ '. . " , . , . ASTASI^A.

Carapace present, . . ... DINOBRYINA.
Cilia or seta3 present.

Carapace absent, ... . :•-•.• CYCLIDINA.

Carapace present, . > ' . . . PERIDIN^A.

B. Intestinal tube present.

Orifice single.

Carapace absent, . # .. ;" . . VORTICELLINA.
Carapace present, . . .; . . . OPHRYDINA.
Two opposite orifices.

Carapace absent, .... . . ENCHELIA.

Carapace present, . . ., . . COLEPINA.
Orifices differently placed.
Carapace none.

No tail, but a proboscis, .> . TRACHELINA.
Tail present, mouth anterior, . OPHRYOCERCINA.
Carapace present, . . .••/... ASPIDISCINA.
Orifices ventral.

Carapace absent.

Motion by cilia, .... COLPODEA.

Motion by organs, .... OXYTRICHINA.

Carapace present, . . . . . EUPLOTA.

IV. ROTATORIA OR WHEEL ANIMALCULES. — These are
microscopic, aquatic, transparent animals, of a higher
organization than the Infusoria, and belonging in all
probability to the class Vermes. Their chief interest to
the microscopist is derived from the possession of a more
or less lobed, retractile disk, covered with cilia, which,
when in motion, resemble revolving wheels. They have
also a complicated dental apparatus, and generally a dis-
tinct alimentary canal, and are reproduced by ova. Some
are more or less covered by a carapace, and in most there
is a retractile tail-like foot, sometimes terminated by a
suctorial disk or a pair of claw-like processes. The ner-
vous and vascular systems are not well known, although
traces of them are seen. The young of some possess an
eye which often disappears in the adult. They are re-

164 THE MICROSCOPIST.

markably tenacious of life, having in some instances re-
vived after having been kept dry for several years.

M. Dujardin divides the Rotifera into four groups or
natural families :

1. Those attached by the foot, which is prolonged into
a pedicle. It includes two families, the Floscularians and
the MdicertianS) in the first of which the sheath or cara-
pace is transparent, and in the other composed of little
rounded pellets (Plate XIII, Fig. 120).

2. The common Rotifer and its allies, which swim freely
or attach themselves by the foot at will (Plate XIII, Fig.
121).

3. Those which are seldom or never attached, the Bra-
chionians and the Furcularians. The former are short,
broad, and flat, and inclosed in a sort of cuirass ; the latter
are named from a bifurcated, forcep-like foot (Plate XIV,
Fig. 122).

4. The Tardigrada or water bears. These have no
ciliated lobes, but are in other respects like their allies,
and seem to be a connecting link between the Rotifers
and worms. The segments of the body, except the head,
bear two fleshy protuberances furnished with four curved
hooks.*

Y. POLYPS. — The animals of this class were formerly
called Zoophytes, or animal flowers. They are the most
important of coral-making animals, although the Hydroids
and Bryozoa, together with some Algae, as the Nullipores,
share with them the formation of coral, which is a secre-
tion of calcareous matter. Dana's work on corals gives a
classification, of which we present a summary.

A good idea of a polyp may be had from comparison
with the garden aster, the most common form of a polyp
flower being a disk fringed with petal-like organs called
tentacles.

The internal structure, like the external, is radiate, and

* Carpenter on the Microscope.

PLATE XIII.

FIG. 119.

Fissiparous multiplication of Chilodon cucullvlus.

FIG. 120.

FIG. 121.

B A

Rodifer vulgaris, as seen at A, with
the wheels drawn in, and at B with
the wheels expanded; a, mouth; 6,
eye-spots; c, wheels; d, calcar (an-
tenna?); e, jaws and teeth; /, ali-
mentary canal ; g, glandular (?) mass
enclosing it; h, longitudinal mus-
cles ; i, i, tubes of water vascular
system; k, young animal; /.cloaca.

Stephanoceros Eichornii.

THE MICROSCOPE IN ZOOLOGY. 165

the cavity of the body is divided by septa into narrow
compartments. The walls contain circular and longitu-
dinal muscles, which serve for contraction of the body,
which is afterwards expanded by an injection or absorp-
tion of water by the mouth.

The most interesting part of the structure of these
animals, to the microscopist, is the multitude of lasso-cells,
called also nettling -cells, thread capsules, and cnidce, which
stud the tentacles and other parts of the body, and by
means of which the prey of the polyp is at once pierced
and poisoned. A small piece of the tentacle of a sea
anemone placed in a compressorium under the microscope,
and subjected to gentle pressure, will show the protrusion
of many little dart-like processes attached to thread-like
filaments. Many observations indicate the injection of a
poison through these darts, which is instantly fatal to
small animals (Plate XIV, Fig. 123).

The polyp has no circulating fluid but the results of
digestion mixed with salt water, no bloodvessels but the
vacuities among the tissues, and no passage for excrements
except the mouth and the pores of the body. Reproduc-
tion is both by ova and by buds.

I. Actinoid polyps are related to the Actinea or sea
anemone. The number of tentacles and interior septa
is a multiple of six.

II. Cyathophylloid polyps have the number of tentacles
and septa a multiple of four.

III. Alcyonoid polyps have eight fringed tentacles. The
Alcyonium tribe are among the most beautiful of coral
shrubs. The Gorgonia tribe has reticulated species like
the sea fan, and bears minute calcareous spicules, often
brilliantly colored. The Pennatula tribe is unattached,
and often rod-like, with the polyps variously arranged.

VI. HYDROIDS. — The type of this class is the common
Hydra, which is often found attached to leaves or stems
of aquatic plants, etc. It is seldom over half an inch long.

166 THE MICROSCOPIST.

It has the form of a polyp, with long slender tentacles.
Besides these tentacles with their lasso-cells, it has no
special organs except a mouth and tubular stomach. Like
the fabled Hydra, if its head be cut off another will grow
out, and each fragment will in a short time become a per-
fect animal, supplying whatever is wanting, hence its name
(Plate XIV, Fig. 124). The Hydra has the power of lo-
comotion, bending over and attaching its head until the
tail is brought forward, somewhat after the manner of a
leech.

Compound Hydroids may be likened to a Hydra whose
buds remain attached and develop other buds until an
arborescent structure, called a polypary, is produced. The
stem and branches consist of fleshy tubes with two layers,
the inner one having nutritive functions, and the outer
secreting a hard, calcareous, or horny layer. The indi-
viduals of the colony are of two kinds, the pdypite or
nutritive zooid, resembling the Hydra, and the gonozooid,
or sexual zooid, developed at certain seasons in buds of
particular shape.

To mount compound Hydrozoa, or similar structures,
place the specimen alive in a cell, and add alcohol drop
by drop to the sea-water ; this will cause the animals to
protrude and render their tentacles rigid. Then replace
the alcohol with Goadby's solution, dilute glycerin, or
other preserving fluid.

VII. ACALEPIIS, or sea-nettles, are of all sizes, from an
almost invisible speck to a yard in diameter. They swarm
in almost every sea, and are frequently cast upon the
beach by the waves. They are transparent, floating free,
discoid or spheroid, often shaped like a mushroom or um-
brella, and their organs are arranged radiately round an
axis occupied by the pedicle or stalk. They are furnished
with muscular, digestive, vascular, and nervous systems.
They were formerly divided into

1. Pulrnonigrada, from their movements being effected

PLATE XIV.

FIG. 122.

Nolens quadricornis :— A, dorsal view ; B, side view.

Hydra jusca in gemmation.

Filiferous capsules of Helianthoid Polypes :— A,B,
Corynactis Allmanni; c, E, F, Caryophyllia Smithii ;
D, G, Actinia crass icornis; H, Actinia Candida.

THE MICROSCOPE IN ZOOLOGY. 167

by a rhythmical contraction and dilation, as in Rhizistoma,
etc. 2. Cilograda, moving by narrow bands of vibratile
cilia variously disposed over the body. In Beroe the cilia
are transformed into flat fin-like shutters, arranged in
eight longitudinal bands. InVenus's girdle, Cesium Ve-
neriS) the margins of a gelatinous ribbon are fringed with
cilia. 3. Physograda, which move by means of an expan-
sile bladder, as the Physalia, or Portuguese man of war.
4. Cirrigrada, possessing a sort of cartilaginous skeleton,
and furnished with appendages called cirri, serving as oars
and for prehension, as Porpita and Velella. In the latter
there is also a subcartilaginous plate rising at right angles
from the surface supporting a delicate membrane, which
acts as a sail.

This classification has been laid aside since the micro-
scopic discovery of the close relationship between the
Hydrozoa and the Medusoid Acalephs, and the latter are
now subdivided into the " naked-eyed " and the " covered-
eyed " Acalephs. The alternation of generations, page
126, is fully illustrated in this class. The embryo emerges
as a ciliated gemmule, resembling one of the Infusoria.
One end contracts and attaches itself so as to form a foot,
while the other enlarges and becomes a mouth, from which
four tubercles sprout and become tentacles. Thus a Hy-
dra-like polyp is formed, which acquires additional tenta-
cles. From such a polyp many colonies may rise by gem-
mation or budding, but after a time the polyp becomes
elongated, and constricted below the mouth. The con-
stricted part gives origin to other tentacles, while similar
constrictions are repeated round the lower parts of the
body, so as to divide it into a series of saucer-like disks,
which are successively detached and become Medusae
(Plate XV, Figs. 125, 126).

VIII. ECHINODERMS. — This class includes the star-fishes,
the sea-urchins or sea-eggs, the sea-slugs, and the crinoids
or stone lilies of former ages. If we imagine a polyp with

168 THE MICROSCOPIST.

a long stem to secrete calcareous matter, not merely exter-
nally, but in the substance of its body and tentacles, such
polyp when dried would present some such appearance as
the fossil Encrinoid Echinode'rms of past times. The im-
agination of such a polyp without a stem, and having
sucker-like disks on its arms, will give us the picture of
a star-fish (Asterias). Imagine the rays diminished and
the central part extended, either flat or globular, and we
have the form of Echini with the spines removed. The
Holothurice have elongated membranous bodies, with im-
bedded spiculse.

The structure of Echinoderms is quite complex, and
belongs to comparative anatomy rather than microscopy,
yet some directions for the study of these forms is essen-
tial to our plan.

Thin sections of the shells, spines, etc., may be made by
first cutting with a fine saw, and rubbing down with a
flat file. They should be smoothed by rubbing on a hone
with water, cemented to a glass slip with balsam, and
carefully ground down to the required thickness. They
may be mounted in fluid balsam.

Many Echinoderms have a sort of internal skeleton
formed of detached plates or spiculse. The membranous
integument of the Holothurise have imbedded calcareous
plates with a reticulated structure, and they are often
furnished with appendages, as prickles, spines, hooks, etc.,
which form beautiful microscopic objects.

The larva of an Echinoderm is a peculiar zooid, which
develops by a sort of internal gemmation. One of the
most remarkable of these larvae has been called Bipin-
naria.

IX. BRYOZOA OR POLYZOA. — Microscopic research has
removed this class from the polyps, which they resemble,
to the molluscan sub-kingdom. They have a group of
ciliated tentacles round the mouth, but have a digestive
system far more complex than polyps. They form delicate

PLATE XV.

FIG. 125.

FIG. 127.

•

Development of Medusa buds in Syn-
choryna Snrsii.

FIG 126.

A, Portion of Cellularia ciliata, enlarged ; B,
one of the " bird's-head " of Bvgula avicularia,
more highly magnified, and seen in the act of
grasping another.

FIG. 128.

Successive stages of development of Medusa
buds from Slrobila larva.

Sertularia cupressina :— A, natural size;
B, portion magnified.

THE MICROSCOPE IN ZOOLOGY. 169

corals, either membranous or calcareous, made up of minute
cabin-like cells, which are either thin crusts on sea-weeds,
rocks, etc., or slender moss-like tufts, .or groups of thin
curving plates, or net-like fronds, and sometimes thread-
like lines or open reticulations. The cells of a group have
no connection with a common tube, as the Hydroids, but
the alimentary system of each little Bryozoon is indepen-
dent.

Many of the Polyzoa have curious appendages to their
cells, of two kinds ; the first are called birds'-head pro-
cesses or avicularia. They consist of a body, a hinge or
lower jaw-like process, and a stalk. The lower portion is
moved by an elevator and depressor muscle, and during
life the motion is constant. The second kind, or vibracula,
is a hollow process from which vibratile filaments project
(Plate XV, Figs. 127, 128).

X. TUNICATA. — These molluscs are so named from the
leathery or cartilaginous tunic which envelops them, and
which often contains calcareous spicula. Like the Bryo-
zoa they tend to produce composite structures by gemma-
tion, but they have no ciliated tentacles. They are of
most interest to the microscopist from the peculiar actions
of their respiratory and circulatory organs, which may be
seen through the transparent walls of small specimens.
The branchial or respiratory sac has a beautiful network
of bloodvessels, and is studded with vibratile cilia for dif-
fusing water over the membrane. The circulation is re-
markable from the alternation of its direction.

The smaller Tunicata are usually found aggregate, in-
vesting rocks, stones and shells, or sea-weeds ; a few are
free.

Synopsis of the Families.

A. Attached ; mantle and test united only at the ori-
fices.

1. Botryllidce. — Bodies united into systems.

170 THE M1CROSCOPIST.

2. Clavelinidce. — Bodies distinct, but connected by a
common root thread.

3. AscidiadcB. — Bodies unconnected.

B. Free ; mantle and test united throughout.

4. Pelonceadce. — Orifices near together.

5. Salpadce. — Orifices at opposite ends.

XI. CONCHIFERA. — This class consists of bivalve mol-
luscs, and is chiefly interesting to the microscopist from
the ciliary motion on their gills and the structure of the
shell.

The ciliary motion may be observed in the oyster or
mussel, by detaching a small piece of one of the bands
which run parallel with the edge of the open shell, placing
it on a glass slide in a drop of the liquid from the shell,
separating the bars with needles, and covering it with
thin glass ; or the fragment may be placed in the live box
and submitted to pressure. The peculiar movement of
each cilium requires a high magnifying power. It appears
to serve the double purpose of aeration of the blood and
the production of a current for the supply of aliment.

Dr. Carpenter has shown that the shells of molluscs
possess definite structure. In the Margaritacece, the exter-
nal layer is prismatic, and the internal nacreous. The
nacreous or iridescent lustre depends on a series of grooved
lines produced by laminae more or less oblique to the plane
of the surface. The shells of Terebratulce are marked by
perforations, which pass from one surface to another.
The rudimentary shell of the cuttle-fish (of the class
Cephalopoda), or "cuttle-fish bone," is a beautiful object
either opaque or in the polariscope. Sections may be
made in various directions with a sharp knife, and
mounted as opaque objects or in balsam.

XII. GASTEROPODA. — These molluscs are either naked,
as the slug, or have univalve shells, as the snail, the lim-
pet, or the whelk. As in the other classes referred to,
the details of anatomical structure are full of interest ;

PLATE XVI.

FIG. 130.

FIG. 129

A, female of Cyclops quadricornis ; — a, body ; 6, tail ;
c, antenna; d, antennule; e, feet; /, plumose setae of
tail ;— B, tail, with external egg-sacs ; c, D, E, F, G,
successive stages of development of young.

FIG. 131.

Metamorphosis of Carcinus mcenas: — A, first stage ; B, second stage ; c, third stage,
in which it begins to assume the adult form ; D, perfect form.

THE MICROSCOPE IN ZOOLOGY. 171

but to the microscopist the palate, or tongue as it is called
— a tube which passes beneath the mouth, opening ob-
liquely in front, and which is covered with transverse
rows of minute teeth set upon plates — presents characters
of great value in classification. These palates require
careful dissection, and when niounted in balsam become
beautiful polariscope objects (Plate XVI, Fig. 129).

XIII. CEPHALOPODA. — The crystalline lens in the eye of
the cuttle-fish is said to be of the same form as the well-
known " Coddington lens." The skin of this class con-
tains a curious provision for changing its hue, consisting
of large pigment-cells containing coloring matter of vari-
ous tints.

The suckers, or prehensile disks, on the arms of cephal-
opods often make interesting opaque objects when dried.

XIY. ENTOZOA. — These are parasitic animals belonging
to the class of worms. They are characterized by the
absence or low development of the nutritive system, and
the extraordinary development of their reproductive or-
gans. Thus the Tcenia or tapeworm has neither mouth
nor stomach, the so-called " head" being merely an organ
for attachment, while each segment of the " body " con-
tains repetitions of a complex generative apparatus.

Among the Nematoid or roundworms, the Anguillulce,
or little eel-like worms, found in sour paste, vinegar, etc.,
as well as the Trichina spiralis, inhabiting the voluntary
muscles, are generally classified.

ORDER I. STERELMINTHA. — Alimentary canal absent or
indistinct.

FAMILY 1. Cestoidea. — Tapeworms; body strap-shaped,
divided into transverse joints ; alimentary canal indistinct.
The cystic Entozoa (Echinococcus, etc.) are nurse or larval
forms of Cestoidea.

FAMILY 2. Trematoda. — Body mostly flattened ; alimen-
tary canal distinct ; branched.

172 THE MICROSCOPIST.

FAMILY 3. Acanthocephala. — Body flattened, transversely
wrinkled ; sexual organs in separate individuals.

FAMILY 4. Gordiar.ea (Hairworms). — Body filamentous,
cylindrical ; alimentary canal present ; sexes distinct.

FAMILY 5. Protozoidea or Gregarinida. — Probably larval
forms.

ORDER II. C^LELMINTHA. — Alimentary canal distinct.

FAMILY 1. Nematoidea (Roundworms). — Body cylindri-
cal, hollow ; sexes separate.

The Enoplidce tribe is distinguished by an armature of
hooks or styles round the mouth. Most of them are
microscopic.

XY. ANNULATA (Red-blooded Worms). — Some of these,
as the Serpula, etc., are inclosed in tubes formed of a shelly
secretion, or built up of grains of sand, etc., agglutinated
together. Many have special respiratory appendages to
their heads, in which the microscope will exhibit the cir-
culation. The worms of the Nais tribe, also, are so trans-
parent as to be peculiarly fitted for microscopic study of
structure. The dental apparatus of the leech consists of
a triangular aperture in a sucking disk, furnished with
three semicircular horny plates, each bordered with a row
of eighty to ninety teeth, which act like a saw.

ORDER 1. TURBELLARIA. — Body bilateral, soft, covered
with vibratile cilia, not segmented ; eyes distinct ; sexless
or hermaphrodite.

ORDER 2. SUCTORIA (Apoda). — Body elongate, ringed,
without bristles or foot-like tubercles; locomotion by
sucking-disks ; no external branchiae.

ORDER 3. SETIGRADA (Choetopoda). — Body ringed, elon-
gate, with feet or setigerous rudiments of them ; external
branchise usually present.

XVI. CRUSTACEA. — In the family of Isopoda the micros-
copist will find the Ascellus vulgaris, or water wood-louse,
of great interest, as readily exhibiting the dorsal vessel
and circulating fluids.

THE MICROSCOPE IN ZOOLOGY. 173

The family of Entomostraca contains a number of gen-
era, nearly all of which are but just visible to the naked
eye. They are distinguished by the inclosure of the body
in a horny or shelly case, often resembling a bivalve shell,
though sometimes of a single piece. The tribe of Lophy-
ropoda (bristly -footed), or " water-fleas," is divided into
two orders, the first of which, Q&tracoda, is characterized
by a bivalve shell, a small number of legs, and the absence
of an external ovary. A familiar member of this order,
the little Cypris,\$ common in pools and streams, and may
be recognized by its two pairs of antennae, the first of
which is jointed and tufted, while the second is directed
downwards like legs. It has two pairs of legs, the poste-
rior of which do not appear outside the shell.

The order Copepoda has a jointed shell, like a buckler,
almost inclosing the head and thorax. To this belongs
the genus Cyclops (named from its single eye), the female
of which carries on either side of the abdomen an egg
capsule, or external ovarium, in which the ova undergo
their earlier stages of development (Plate XVI, Fig. 130).

The Daphnia pulex, or arborescent water-flea, belongs to
the order Gladocera and tribe Branchiopoda. The other
order of this tribe, the Phyllopoda, has the body divided
into segments, furnished with leaf-like members or " fin
feet."

When first hatched, the larval Entomostraca differ
greatly from the adult. The larval forms of higher
Crustacea resemble adult Entomostraca.

The suctorial Crustacea, order Siphonostoma, are gener-
ally parasitic, mostly affixed to the gills of fishes by means
of hooks, arms, or suckers, arising from or consisting of
modified foot-jaws. The transformations in this order, as
in the Lerncea, seem to be a process of degradation. The
young comes from the egg as active as the young of
Cyclops, which they resemble, and pass through a series
of metamorphoses in which they cast off their locomotive

174 THE MICROSCOPIST.

members and their eyes. The males and females do not
resemble each other.

The order Cirrhipeda consists of the barnacles and their
allies. In their early state they resemble the Entomos-
traca, are unattached, and have eyes. After a series of
metamorphoses they become covered with a bivalve shell,
which is thrown off; the animal then attaches itself by
its head, which in the barnacle becomes an elongated
pedicle, and in Balanus expands into a disk. The first
thoracic segment produces the "multivalve" shell, while
the other segments evolve the six pairs of cirrhi, which
are slender, tendril-like appendages, fringed with ciliated
filaments.

In the order Amphipoda, the Gammarus pulex, or fresh-
water shrimp, and the Talitrus saltator, or sandhopper,
may be interesting to the microscopist.

The order Decapoda, to which belong the crab, lobster,
shrimp, etc., is of interest, from the structure of the shell
and the phenomena of metamorphosis. The shell usually
consists of a horny structureless layer exteriorly, an areo-
lated stratum, and a laminated tubular substance. The
difference between the adult and larval forms in this order
is so great that the young crab was formerly considered
a distinct germs, Zoea (Plate XVI, Fig. 131).

For the preservation of specimens of Crustacea, Dr.
Carpenter recommends glycerin jelly as the best medium.

XVII. INSECTS. — Many insects may be mounted dry,
as opaque objects. They may be arranged in position by
the use of hot water or steam. Those which are trans-
parent enough may be mounted in balsam, and very deli-
cate ones in fluid. To display the external chitinous cov-
ering of an entire insect, it may be soaked in strong liquor
potassse, and the internal parts squeezed out in a saucer
of water by gently rolling over it a camel's-hair brush.
It may be put on a slide, and the cover fastened by tying
with a thread. It should then be soaked in turpentine

THE MICROSCOPE IN ZOOLOGY. 175

until quite transparent, when it may be removed, the tur-
pentine partially drained off, and a solution of balsam in
chloroform allowed to insinuate itself by capillary attrac-
tion. Gentle heat from a spirit-lamp will be useful at this
stage of the mounting.

Small insects hardly need soaking in caustic potash, as
turpentine or oil of cloves will render them after awhile
quite transparent, and their internal organs are beautifully
seen in the binocular microscope. Thin sections of insects
are instructive, and maybe made with a section-cutter by
first saturating the body with thick gum mucilage, and
then incasing in melted paraffin.

Many insects and insect preparations are well preserved
in glycerin.

The eggs of insects are often interesting objects, and
should be mounted in fluid.

Wing cases of beetles are often very brilliant opaque
objects. Some are covered with iridescent scales, and
others have branching hairs. Many are improved by
balsam, and this may be determined by touching with
turpentine before mounting.

Scales of Lepidoptera, etc., may be exhibited in their
natural arrangement by mounting a small piece of wing
dry. If desired as test objects, a slide or thin cover, after
having been breathed on, may be slightly pressed on the
wing or body of the insect. The scales are really flattened
cells, analogous to the epidermic cells of higher animals.
Some have their walls strengthened by longitudinal ribs,
while others, as the Podurce, show a beaded appearance
under high powers from corrugation. Dr. Carpenter be-
lieves the exclamation marks in the scales of the latter to
be the most valuable test of the excellence of an objective.

Hairs of insects are often branched or tufted. The hair
of the bee shows prismatic colors if the chromatic aberra-
tion of the object-glass is not exactly neutralized.

Antennce vary greatly in form, and are often useful in

176 THE MICROSCOPIST.

classification (Plate XVII, Fig. 132). Thus in the Cole-
optera we have the Serricornes, or serrated antennae; the
Clavicornes, or clubbed ; the Palpicornes, with antennae no
larger than palpi ; the Lamellicornes, with leaf-like appen-
dages to the antennae ; 'and the Longicornes, with antennae
as long or longer than the body. Nerve-fibres, ending in
minute cavities in the antennae, have been traced, which
are supposed to be organs of hearing. The antennae should
be bleached to exhibit them. The bleaching process is
also useful for other parts of insects. The bleaching fluid
consists of a drachm of chlorate of potass in about two
drachms of water, to which is added about a drachm of
hydrochloric acid.

Compound eyes of insects are always interesting. They
are quite conspicuous, and often contain thousands of
facets, or minute eyes, called ocelli (Plate XVII, A B, Fig.
133). Besides these, insects possess rudimentary single
eyes, like those of the Arachnids. These are at the top
of the head, and are termed stemmata (Plate XVII, a,
Fig. 133). To display the " corneules," or exterior layer
of the compound eye, the pigment must be carefully
brushed away after maceration. A number of notches
may then be made around the edge, the membrane flat-
tened on a slide, and mounted in balsam. Vertical sec-
tions may be made while fresh, so as to trace the relations
of the optic nerve, etc. The dissecting microscope arid
needles will be found useful (Plate XVII, Fig. 132).

Mouths of insects present great varieties. In the beetles
the mouth consists of a pair of mandibles, opening later-
ally ; a second pair, called maxillae ; a labrum or upper
lip ; an under lip or labium ; one or two pairs of jointed
appendages to the maxillae, termed maxillary palpi ; and
a pair of labial palpi. The labium is often composed of
distinct parts, the first of which is called the mentum or
chin, and the anterior part the ligula or tongue. This
latter part is greatly developed in the fly, and presents

PLATE XVII.

Tongue of common Fly.

Foot of Fly.

FIG. 136.

Traeheal system of Nepa (Water-scorpion).

THE MICROSCOPE IN ZOOLOGY. 177

a curious modification of tracheal structure, which is
thought to serve the function of suction (Plate XVII,
Fig. 134). The tongue of the bee is also an interesting
object. In the Diptera the labrum, maxillae, mandibles,
etc., are converted into delicate lancets, termed setae, and
are used to puncture the epidermis of animals or plants,
from which the juices may be drawn by the proboscis.
In the Lepidoptera the labrum and mandibles are reduced
to minute plates, while the maxillae are greatly elongated,
and are united to form the haustellum, or true proboscis,
which contains a tube for suction.

Feet. — These organs vary with the habits of life in dif-
ferent species. The limb consists of five divisions: the
coxa or hip, the trochanter, the femur or thigh, the tibia
or shank, and the tarsus or foot. This last has usually
five joints, but sometimes less. The Coleoptera are subdi-
vided into groups, according as the tarsus consists of five,
four, or three segments. The last joint is furnished with
hooks or claws, and in the fly, etc., the foot is also
furnished with membranous expansions, called pulvilli.
These latter have numerous hairs, each of which has a
minute disk at its extremity. By these, probably by the
secretion of a viscid material, the insect is enabled to
walk on glass, etc., in opposition to gravity (Plate XVII,
Fig. 135). In the Dytiscus, the inner side of the leg is
furnished with disks or suckers of considerable size.
They may be mounted as opaque objects. Stings and
Ovipositors also present a great variety of structure, and
may be best mounted in balsam.

The alimentary canal in insects presents many diversi-
ties. As in higher animals, it is shorter in flesh-eaters
than in feeders on vegetables. It consists of: 1. The
oesophagus, which is sometimes dilated to form a crop.

2. The muscular stomach, or gizzard, whose lining mem-
brane is covered with plates, or teeth, for trituration.

3. A cylindrical true stomach, in which digestion takes

12

178 THE MICROSCOPIST.

place. 4. The small intestine, terminating in 5, the large
intestine or colon. The colon of most insects in the
imago or perfect state, never in larvae or pupse, contains
from four to six organs of doubtful nature arranged in
pairs. They are transparent, round, or oval tubercles
projecting inside the colon, traversed by tufts of tracheae,
and sometimes with a horny ring at the base.

The salivary glands are sacs or tubes of variable form
and length, terminating near the mouth. A distinct liver
is absent, its function being performed by glandular cells
in the walls of the stomach. Many insects, however,
have ceecal appendages to the stomach which secrete bile.
Some have tubular cseca appended to the small intestine,
probably representing a pancreas. In the interspaces of
the various abdominal organs, is found a curious organ
called the fatty body, which attains its development at
the close of the larval period, and appears to form a res-
ervoir of nourishment for the pupa. It consists of fat-
cells imbedded in a reticular tissue, and is traversed by
slender tracheae.

The Malpighian vessels are slender, mostly tubular
glands, caecal or uniting with each other, w^hich open into
the pyloric end of the stomach, and as uric acid has been
found in them, are thought to serve the functions of a
kidney. Some consider the renal organ to be represented
by certain long vessels convoluted on the colon, and open-
ing near the anus.

Other glandular organs occur in insects, as cysts in the
integument, called glandulse odoriferse ; poison glands,
attached to the sting in many females ; and silk-secreting
glands, coiled in the sides of the body and opening out-
side the mouth.

The heart is a long contractile vessel situated in the
back. It is constricted at intervals. The posterior part
acts as a heart, and the anterior represents an aorta, and
conveys blood to the body. From the anterior end the

THE MICROSCOPE IN ZOOLOGY. 179

olood passes in currents in all directions, without vascular
walls, running into the antennae, wings, extremities, etc.,
and returning as a venous current, forming two lateral
currents towards the end of the abdomen, it is brought
by the diastole of the heart through lateral fissures ex-
isting in it.

The respiration is effected by means of tracheae, two
or more large vessels running longitudinally, giving off
branches in all directions, and opening to the air by short
tubes, connected at the sides of the body with orifices
called spiracles. Aquatic larvae often have branchiae in
the form of plates, leaves, or hairs, through which the
tracheae ramify (Plate XVII, Fig. 136).

The nervous system consists of a series of ganglia ar-
ranged in pairs, one for each segment of the body. They
are situated between the alimentary canal and the under
surface of the body, and are usually connected by longi-
tudinal nervous cords. From the ganglia nerves are dis-
tributed to all parts.

The muscular system of insects is quite extensive. Ly-
onet dissected and described more than four thousand in
the caterpillar of the goat-moth (Cossus ligniperda].

XVIII. ARACHNIDA. — This class of animals includes
mites, ticks, spiders, and scorpions. They are destitute
of antennae ; the head and thorax are united ; they have
simple eyes (ocelli), and eight jointed legs.

The cheese-mite, the u ticks," the itch-insect (Sarcoptes
scabies), and the Demodex folliculorum, which is parasitic
in the sebaceous follicles of the skin of the face, are com-
"mon examples of Acari. They are best mounted in fluid.

The respiratory apparatus in spiders differs from that
of insects, the spiracles opening into respiratory sacs, which
contain leaf-like folds for aeration of blood! The spinning
apparatus is also interesting.

The minute anatomy of vertebrated animals affords the

180 THE MICROSCOPIST.

microscopist numerous specimens, but the details will be
best understood from the following chapter.

As the classification of the Invertebrata is subject to
great variation, the following table, after Nicholson, is
added for the sake of comparison :

INVERTEBRATE ANIMALS.

SUB-KINGDOM I. — PROTOZOA.

CLASS I. GREGARINIDJE. — Parasitic Protozoa, destitute
of a mouth, and destitute of pseudopodia. Ex., Gregarina.

CLASS II. RHIZOPODA. — Simple or compound ; destitute
of a mouth ; capable of putting forth pseudopodia.

CLASS III. INFUSORIA. — Generally with a mouth ; no
pseudopodia ; with vibratile cilia or contractile filaments.

SUB-KINGDOM II. — CCELENTERATA.

CLASS I. HYDROZOA. — Walls of the digestive sac not
separated from those of the body cavity ; reproductive
organs external.

Sub-class 1. Hydroida. — Ex., Hydra. Tubularia (pipe-
coralline). Sertularia (sea-fir).

Sub-class 2. Siphonophora. — Ex., Diphyes. Physalia
(Portuguese man-of-war).

Sub-class 3. Discophora. — Ex., Naked-eyed Medusae, or
Jelly-fish.

Sub-class 4. Lucernarida. — Ex., Sea-nettles, or " Hidden-
eyed " Medusae.

CLASS II. ACTINOZOA. — Digestive sac distinct from the
general cavity, but opening into it ; reproductive organs
internal.

Order 1. Zoantharia. — Ex., Sea- Anemones (Actinia).
Reef-building corals.

Order 2. Alcyonaria. — Ex., Sea-pen. Red coral.

Order 3. Ctenophora. — Ex., Cestum (Venus's girdle).

THE MICROSCOPE IN ZOOLOGY. 181

SUB-KINGDOM III. — ANNULOIDA.

CLASS I. ECHINODERMATA.. — Integument calcareous or
leathery ; adult radiate.

Order 1. Crinoidea. — Ex., Comatula.

Order 2. Blastoidea. — (Extinct.)

Order 3. Cystoidea. — (Extinct.)

Order 4. Ophiuroidea. — Ex., Brittle-star.

Order 5. Aster oidea. — Ex., Star-fish.

Order 6. Echinoidea. — Ex., Sea-urchins.

Order 7. Holothur oidea. — Ex., Sea-cucumbers.

CLASS II. SCOLECIDA — Soft-bodied, cylindrical, or flat ;
nervous sj^stem not radiate ; of one or two ganglia.

Order 1. Tceniada. — Ex., Tapeworms.

Order 2. Trematoda.—Ex., Flukes.

Order 3. Tarbellaria — Ex., Planarians.

Order 4. Acantkocephala. — Ex., Echinorynchus.

Order 5. Gordiacea. — Ex., Hairworms

Order 6. Nematoda. — Ex., Round worms.

Order 7. Rotifera. — Ex., Wheel animalcules.

SUB-KINGDOM IV. — ANNULOSA.

DIVISION A. ANARTHROPODA. — Locomotive appendages
not distinctly jointed or articulated to the body.

CLASS I. GEPHYREA. — Ex., Spoon-worms.

CLASS II. ANNELIDA. — Ex., Leeches (Hirundinidse).
Earth-worms (Oligochseta). Tube-worms (Tubicola).
Sand-worms and Sea-worms (Errantia).

CLASS III. CH^ETOGNATHA. — Ex., Sagitta.

DIVISION B. ARTHROPODA — Locomotive appendages
jointed to the body.

CLASS I. CRUSTACEA. — Ex., Decapoda. Isopoda. Xi-
phosura. Cirri pedia.

CLASS II. ARACHNIDA. — Ex., Podosomata (sea-spiders).
Acarina (mites). Pedipalpi (scorpions). Araneida (spi-
ders).

182 THE MICROSCOPIST.

CLASS III. MYRIAPODA.— Ex., Centipedes.

CLASS IV. INSECTA.— Ex., Anoplura (lice). Mallophaga
(bird lice). Thysanura (spring-tails). Hemiptera. Or-
thoptera. Neuroptera. Diptera. Lepidoptera. Hyme-
noptera. Coleoptera.

SUB-KINGDOM V. — MOLLUSCA.

DIVISION A. MOLLUSCOIDA. — A single ganglion, or pair
of ganglia ; heart imperfect, or none.

CLASS I. POLYZOA. — Ex., Sea-mats (Flustra).

CLASS II. TUNICATA. — Ex., Ascidia (Sea-squirts).

CLASS III. BRACHIOPODA. — Ex., Terebratula.

DIVISION B. MOLLUSCA PROPER. — Three pairs of gan-
glia ; heart of at least two chambers.

CLASS I. LAMELLIBRANCHIATA. — Ex., Oyster. Mussel.

CLASS II. GASTEROPODA. — Ex., Buccinium. Helix.
Doris.

CLASS III. PTEROPODA. — Ex., Cleodora.

CLASS IY. CEPHALOPODA.

Order 1. Dibranchiata. — Ex., Poulp. Paper Nautilus.

Order 2. Tetrabranchiata. — Ex., Pearly Nautilus.

CHAPTER XII.

THE MICROSCOPE IN ANIMAL HISTOLOGY.

IN Chapter IX we described the elementary living
substance, or bioplasm, from which all organized struc-
tures proceed, with an outline of its morphology, chemis-
try, and physiology. In Chapter X we treated of Vege-
table Histology, or the elementary tissues and organs
which pertain to vegetable life. We now consider the

THE MICROSCOPE IN ANIMAL HISTOLOGY. 183

structure of formed material in animals, with special
reference to the minute anatomy of the human body.
Following the generalization of Dr. Beale, page 118, we
may classify histological structures as follows :
\

A. INORGANIC AND ORGANIC ELEMENTS OR PABULUM.

Eesulting in

B. BIOPLASM ; or, O. II. C. and K, with other chemical

elements, plus, The cause of life.
From this results :

C. FORMED MATERIAL, consisting of,

I. CHEMICAL PRODUCTS ; Organic Compounds, etc.

II. MORPHOLOGICAL PRODUCTS. 1. Granules; 2. Globules;

3. Fibres ; 4. Membrane.
Forming Tissues. 1. Simple ; 2. Compound.
Arranged in Organs. 1. Vegetative ; 2. Animal.

I. THE CHEMICAL PRODUCTS of Bioplasm are very nu-
merous, and belong to the science of Histo-Chemistry.
Our plan allows us to do little more than to enumerate
the principal groups. It has already been stated that the
true chemical- structure of bioplasm, or living sarcode,
(protoplasm in a living state) is unknown, since it is only
possible to analyze the dead cell substance. Of the rela-
tion of the oxygen, hydrogen, carbon, and nitrogen, etc.,
which constitute its "physical basis," we can only specu-
late, or imagine. See Chemistry of Cells and their Products,
page 122.

The chemical transformations of cell-substance into
" formed material " consist chiefly, with water and min-
eral matter, of certain groups of organic principles, some-
times called albuminous or " protein " substances, and
their nearer derivatives, as glutin-yielding and elastic
matter, with fat and pigments. These materials are sub-
ject to constant secondary changes or transformations,

184 THE MICROSCOPIST.

since they are not laid down in the living body once for
all. They are also subject to constant decay, or ultimate
decomposition. Histo-Chemistry must, therefore, be always
a difficult study, since we can rarely isolate the tissues for
examination, nor always tell when a substance is super-
fluous aliment, formative or retrogressive material. From
a limited number of formative or histogenic materials, we
have a host of changed or decomposition products.

Frey's Histology and Histo-Chemistry, Strieker's Hand-
Book of Histology, and Beale's Bioplasm, are among the
most useful books to the student in this department.

Frey subdivides the groups of organic principles as fol-
lows :

I. Albuminous or Protein Compounds. — Albumen. Fi-
brin. Myosin. Casein. Globulin. Peptones. Ferments ?

II. Hwmoglobulin.

III. Formative (Histogenic) Derivatives from Albuminous
Substances. — Keratin. Mucin. Colloid. Glutin-yielding
substances. Collagin and Glutin. Chondrigen and Chon-
drin. Elastin.

IY. Fatty Acids and Fats. — Glycerin. Formic acid.
Acetic acid. Butyric acid. Capronic acid. Palmitic acid.
Stearic acid. Oleic acid. Cerebrin. Cholesterin.

V. Carbohydrates. — The Grape-sugar group, Cane-sugar
group, and Cellulose group ; or Glycogen. Dextrin.
Grape-sugar. Muscle-sugar. Sugar of milk.

VI. Non-Nitrogenous Acids. — Lactic. Oxalic. Succinic.
Carbolic. Taurylic.

VII. Nitrogenous Acids. — Inosinic. Uric. Hippuric.
Glycocholic. Taurocholic.

VIII. Amides, Amido Acids, and Organic Bases. — Urea.
Guanin. Xanthin. Allantoin. Kreatin. Leucin. Ty-
rosin. Glycin. Cholin (KeurinX Taurin. Cystin.

IX. Animal Coloring Matters. — Hsematin. ILemin.
Hrematoidin. Urohsernatin. Melalin. Biliary pigments.

X. Cyanogen Compounds. — Sulpho-cyanogen.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 185

XI. Mineral Constituents. — Oxygen, Nitrogen, Carbonic
acid. Water. Hydrochloric acid. Silicic acid. Calcium
compounds (Phosphate, Carbonate, Chloride, and Fluor-
ide). Magnesium compounds (Phosphate. Carbonate.
Chloride). Sodium compounds (Chloride. Carbonate.
Phosphate. Sulphate). Potassium compounds (Chloride.
Carbonate. Phosphate. Sulphate). Salts of Ammonium
(Chloride. Carbonate). Iron and its Salts (Protochloride.
Phosphate). Manganese. Copper.

The subject of Histology relates properly to cell-struc-
ture (already described, Chapter IX), and its morpho-
logical products, yet its close connection with Histo-chem-
istry renders the foregoing list of substances valuable to
the student.

II. HISTOLOGICAL STRUCTURE is due to the formative
power of bioplasm, or living cell-substance, and is not mere
selection and separation from pabulum, or aliment, since
from the same pabulum, and, so far as we can see, under
the same circumstances, result tissues having different
physical and chemical properties.

In our classification we have arranged the microscopic,
or histological, elements of the tissues as Granules, Glob-
ules, Fibre, and Membrane.

Granules are minute particles of formed material.

Globules are small, homogeneous, round, or oval bodies.
If composed of albuminous matter they are rendered trans-
parent by acetic acid, and are dissolved by potash and
soda. If consisting of fat they are soluble in ether and
unaltered by acetic acid. If they are earthy matters they
are dissolved by acids and unchanged by alkalies.

Fibres appear as fine lines, cylindrical threads, or flat-
tened bands, parallel, or at various angles.

Membrane is an expansion of material. It may be trans-
parent and homogeneous, and may be recognized by plaits
or folds, which sometimes simulate fibres, or it may be
granular, or bear earthy particles.

186 THE MICROSCOPIST.

From these elements result the simple and compound
tissues.

The Simple Tissues may be divided into

1. Cells with intermediate fluid, as Blood, Lymph,
Chyle, Mucus, and Pus.

2. Epithelium and its appendages.

3. Connective Substances. — Cartilage. Fat. Connec-
tive tissue. Bone. Dentine.

The Compound Tissues are Muscle, Nerve, Gland, and
Vascular tissues.

These are formed into Organs.

1. Vegetative. — The Circulatory, Respiratory, Diges-
tive, Urinary, and Generative organs.

2. Animal. — The Bony, Muscular, Nervous, and Sensory
apparatus.

We shall attempt a brief description of these tissues
and organs, as illustrated by the microscope and modern
methods of research.

I. SIMPLE TISSUES.
1. CELLS WITH INTERMEDIATE FLUID.

I. The Blood.

The microscope shows blood to consist, especially in
man and the higher animals, of red corpuscles, colorless
corpuscles, and the fluid in which they are suspended.

1. Blood Plasma, or Liquor Sanguinis. — This is a color-
less and apparently structureless fluid, but when removed
from the body, fibrin separates from it in solid form. In
small quantities of blood this is seen in delicate fibres
crossing each other at various angles.

2. Red-Uood Corpuscles. — These were first discovered by
Svvammerdam, in 1658, in frog's blood, and in that of man
by Lewenhoek, in 1673. Malpighi is said to have first
seen the actual circulation of blood in the web of a frog's

THE MICROSCOPE IN ANIMAL HISTOLOGY. 187

foot. The circulation may be readily observed by ether-
izing a frog, and expanding its foot by means of pins or
thread, upon the stage of the microscope (Plate XVIII,
Fig. 137). The circulation may also be seen in the lung,
mesentery, or extended tongue, of the frog.

The red corpuscles of blood are flattened disks, which
are circular in Mammals, except the camel and lama,
which have elliptic disks. In birds, amphibia, and most
fishes, the disks are elliptic. In a few fishes (the cyclos-
tomata) they are circular. Their color depends on hsemo-
globulin, which plays an important part in the exchange
of respiratory gases. In man the disks are usually double-
concave, with rounded edges. Out of the body they have
a tendency to adhere, or run together, in chains, like rolls
of coin (Plate XVIII, Fig. 138). In the elliptic disks of
birds, etc , there is a distinct nucleus. The size of the
disks varies. In man they are from 0.0045 to 0.0097 mil-
limetre. The smallest disks are in the Moschus Javanicus,
and the largest in Siren lacertina. In the latter they are
from Jg to g'o millimetre.

It is estimated that in a cubic millimetre (about o^th
of an inch) of human blood there are 5,000,000 red cor-
puscles, having a surface of 643 millimetres.

After a variable time from their removal from the ves-
sels they suffer contraction, and assume a stellate, or
mulberry form (Plate XVIII, Fig. 139). This occurs
more rapidly in feverish states of the system. On the
warm stage they suffer still greater alterations. Inden-
tations appear, which cause bea.d-like projections, some
of which become fragments, having molecular motion
(Plate XVIII, Fig. 139). The substance of red corpuscles
is elastic and extensible, and may be seen in the vessels to
elongate and curve so as to adapt themselves to the calibre
of the vessels.

Electric discharges through the red corpuscles produce
various changes of form. Alkalies dissolve, and acids

188 THE M1CROSCOPIST.

cause a precipitate in them. They are tinged by neutral
solutions of carmiuate of ammonia. One-half to 1 per
cent, of salt added to the staining fluid causes the nuclei
only of Amphibian corpuscles to be stained. Chloroform,
tannin, and other reagents, produce various changes,
which suggest a wide field of research connected with
Therapeutics.

The old opinion of the structure of red corpuscles rep-
resented them as vesicles consisting of a membrane and its
contents, but Max Schultze, in 1861, showed that a mem-
brane was not constant. This may be verified by break-
ing them under pressure.

Briicke's experiment on the astringent action of boracic
acid on the blood of Triton, repeated by Strieker and Lan-
kester, shows the red corpuscles to possess a double struc-
ture. There is a body, called (Ecoid ; a porous, non-con-
tractile, soft, transparent mass ; and a retractile substance,
or Zooid, containing the heemoglobulin, which fills the in-
terspaces of the CEcoid. The Zooid seems identical with
simple cell-substance, or bioplasm.

3. Colorless, or White Corpuscles. — These appear to be
simply masses of bioplasm of various sizes. Some are
quite small, and many are larger than the red corpuscles.
Their number is much smaller than the red disks, being
about 1 to 350, or even less. In leucaemia and other dis-
eases their relative number is much greater. In the blood
of cold-blooded animals, and in that of vertebrata, if the
normal temperature is continued by means of a warm
stage, the amoeboid motions are quite perceptible with a
high magnifying power (Plate XVIII, Fig. 139). They
may also be seen to take up small particles of matter into
their interior, such as cinnabar, carmine, milk-globules,
and even portions of the red globules.

Both red and white cells are forced through the unin-
jured walls of small vessels by impeded circulation, but
the white cells thus migrate, by virtue of their vital con-

PLATE XVIII,

FIG. 137.

Capillary circulation in a portion of the web of a Frog's foot.
FIG. 138. FIG. 139

Alterations in form in blood-discs : — 1, Stellate or mul-
berry form; 2, On warm stage; 3, Amoeboid white-cell
forms.

FIG. 140.

Blood-discs : — 1, Eliptic Discs of Amphibia ;
2, Human red-corpuscles ; 3,White or lymph-
corpuscle; 4, Rouleaux of red-discs.

FIG. 141.

Pus-corpuscles: — o, with acetic acid.
FIG. 142.

Mucous corpuscles and epithelium.

Varieties of Epithelium ; — a, Tessalated ; 6, Squamous;
c, Glandular; d, Columnar ; e, Ciliated.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 189

tractility, in the healthy body, and in greater numbers in
diseased states ; in some cases re-entering the lymphatic
circulation, and in others penetrating into various tissues.
The pus-corpuscles appearing in the vicinity of inflamed
parts are shown by this discovery, made by Waller and
Cohnheim, to be nothing but migratory lymphoid or
white cells of the blood. The change of form and place
of these amoeboid cells is readily seen by placing a drop of
frog's blood on a glass cover, and inverting it over a moist
cell. As it coagulates, a zone of serum extends round the
clot, in which the migrated cells will be found.

The colorless cells originate in the chyle and lymph-
systems, although some may come from the spleen and
the medulla of bones, multiplying in the blood itself, and
they pass into red corpuscles. Transitional forms have
been found in the general mass of blood, in the spleen, and
in the marrow of bones.

The white or colorless cells of blood are identical writh
the cells of chyle, lymph, pus, mucus, and saliva. They
are often described under the term leucocytes (white cells.)

The leucocytes of saliva (salivary corpuscles) and of pus
contain granules or globules of formed material, which
exhibit for some time a peculiar dancing movement (see
page 120).

When at rest, or in a lifeless condition, the white cells
are of spheroidal form, and generally exhibit granules and
globules of fat. Acetic acid develops a nucleus, and some-
times splits it into several (Plate XVIII, Fig. 140).

II. Lymph and Chyle.

The vessels of the lymphatic or absorbent system re-
ceive the liquid part of the blood which has passed from
the capillaries, together with the products of decomposi-
tion in the tissues, and return them to the circulation.
The lymphatics of the intestinal canal receive during

190 THE MICROSCOPIST.

digestion a mixture of albuminous and fatty matters,
which is known as chyle, and these vessels have obtained
the name of lacteals. The cells in this fluid are leucocytes,
identical with white cells in blood. They originate in the
lymphatic glands and "Peyer's patches" of the intestine,
and are the corpuscles of these organs which have been
carried off by the fluid stream.

III. Mucus.

Is a tenacious semifluid substance which covers the
surface of mucous membranes. It contains cast-off epi-
thelial and gland-cells, and the mucus corpuscle, which, as
we have before said, is identical with other leucocytes.
Synovial fluid is of similar nature. It is now regarded as
a transformation product of the epithelial cells, and not
to originate as a secretion from special glands (Plate
XVIII, Fig. 141).

2. EPITHELIUM AND ITS APPENDAGES.

Epithelium (from e-i, upon, and Oattw, to sprout) is so
called since it was formerly supposed to sprout from mem-
brane. It is a tissue formed of cells more or less closely
associated, which is found in layers upon external and
internal surfaces. The cells are generally transparent,
with vesicular, homogeneous, or granular nuclei, the lat-
ter being the remains of the original leucocyte or bio-
plast. In the older cells the nucleus is absent, the entire
mass having been transformed.

The forms of epithelial cells vary according to situation
or function. The original form is spheroidal, but changes
by compression, etc.

1. Tessellated or pavement epithelium (Plate XVIII,
a, Fig. 142). These are cells whose formed material is
flattened, and which are united at their edges. They are
sometimes hexagonal, and often polyhedral, in form.

Examples : Serous and synovial membranes ; the pos-

THE MICROSCOPE IN ANIMAL HISTOLOGY. 191

terior layer of the cornea ; the peritoneal surface ; the
interior of bloodvessels, and shut sacs generally.

2. Squamous or scaly epithelium. The cells are flat,
and overlap each other at the edges (Plate XVIII, 6, Fig.
142).

Examples : Epidermis ; many parts of mucous mem-
branes, as the mouth, fundus of bladder, vagina, etc.

3. Glandular epithelium (Plate XVIII, c, Fig. 142).
The cells are round or oval bioplasts, often polyhedral
from pressure, and the formed material is often soft.

Examples : Liver cells, convoluted tubes of kidney, and
interior of glands generally.

4. Columnar epithelium (Plate XVIII, d, Fig. 142).
Cells cylindrical or oblong, arranged side by side. A
bird's-eye view shows them similar to the tessellated form,
hence they should be seen from the side.

Examples : Villi and follicles of intestine, ducts of
glands, urethra, etc.

Some of the columnar or cylinder-cells have a thickened
border or lid perforated with minute pores (Plate XVIII,
/, Fig. 142). They are found in the small intestine, gall-
bladder, and biliary ducts.

5. Ciliated epithelium (Plate XVIII, e, Fig. 142).
These are cylindrical cells having vibratile cilia, whose
motions produce a current in the surrounding fluid.

Examples: The upper and back nasal passages, the
pharynx, bronchi, Fallopian tubes, etc.

The Hair. — Hairs are filiform appendages, composed of
a modified epithelial tissue of rather complex structure.
They originate in a follicle, which is a folding in of the
skin. The shaft of the hair is the portion projecting
above the skin, and the root is concealed in the hair-fol-
licle. The bulb of the root is the rounded terminal part,
which is hollow below, and rests on a papilla which rises
from the floor of the follicle (Plate XIX, Fig. 143). Be-
tween the follicle and hair is a sheath, W7hich is divided

192 THE MICROSCOPIST.

into an external and internal portion. The cells of the
hair may be isolated by sulphuric acid or solution of soda.
They overlap each other like tiles, so as to present undu-
lating or jagged lines across the surface of a fresh hair.
The felting property of wool depends on the looseness of
this overlapping. Air-bubbles are often found in hair,
especially in the medullary or axial portion, and give a
silvery appearance to white hair. The granules of pig-
ment are generally found in the cortical portion.

Nails are nothing more than modified cuticle, depen-
dent for their growth on the vessels of the matrix or bed
of the nail. Their epithelial cells may be demonstrated
by soaking in caustic soda or potash.

Corns, warts, and horn have similar origin.

Enamel of the Teeth. — The minute structure of dental
tissue will be described hereafter, but as the enamel is
generally considered to be of epithelial origin, some ac-
count of it belongs here.

CD

The edge of the jaw is first marked by a slight groove,
known as the dental groove, and is covered with a thick
ridge of epithelium, called the dental ridge (Plate XIX,
Fig. 144, 1 a, 2 a}. The epithelium grows down in a
process which has been called the enamel germ (1 d}.
This becomes doubled by the upward growth of the
dental germ (2, 3,/), which originates from connective
tissue. The epithelial cells become transformed into
enamel columns or prisms.

3. CONNECTIVE SUBSTANCES OR TISSUES.

The term connective tissue has been given to a variety
of structures which probably start from the same rudi-
ments, and have a near connection with each other. It
is unfortunate that a name descriptive of function should
be applied to structure, yet the present state of histology
requires an account of substances thus called.

Connective tissues are all those which may be regarded

PLATE XIX.

FIG. 144. a.

Structure of Human Hair.

FIG. 145.

Connective-tissue elements. From the Frog's Thigh :—
a, contracted cell; ft, ramified ; c, d, motionless gran-
ular cells; /, fibrilise; g, connective-tissue bundle;
«, elastic fibre net-work.

Development of the enamel:— a, dental ridge;
6, young layer of epithelium; c, deep layer; dt
enamel germ ; e, enamel organ ; /, dental germ.

FIG. 146.

White Fibrous Tissue, from Ligament.

FIG. 147.

Yellow Fibrous Tissue, from Ligamentum Nuchse
of Calf.

FIG. 148.

Fatty Tissue.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 193

as basement-membranes, supporting layers or investments
for epithelial structures, blood, lymph, muscle, and nerves.
It includes ordinary connective tissue (white and yellow
fibrous tissues), cartilage, bone, corneal tissue, dentine,
and fatty tissue.

Most of the difficulty found in the consideration of
these tissues arises from discussions relative to the inter-
cellular substance. Max Schultze and Beale agree in re^
garding it to originate from the protoplasm or bioplasm
of cells.

The cells are, according to Frey, originally spheroidal,
with vesicular nuclei, and between them is an albuminous
intercellular substance — a product of the cells, or trans-
formed cells— which usually undergoes fibrillation, while
the cells become stunted, or develop into spindle-shaped'
or stellate elements. Calcification of the intercellular sub-
stance occurs in some of these tissues, as bone and dentine.

The cells of connective tissue present many varieties,
Recklinghausen first observed migrating lymphoid cells
or bioplasts in the cornea of the eye, the tail of the tad-
pole, the peritoneum, and in various other places. The
exit of white corpuscles from the vascular walls renders
it probable that these amoeboid cells originate in the blood.
Granular cells, of various forms — rounded, fusiform, and
stellate — are also observed. Some of the stellate cells
give off anastomosing branches. Pigment cells, filled with
granular pigment, are also met with (Plate XIX, Fig.
145).

In its earliest stages, connective tissue consists of closely-
compressed cells, but in the adult two principal forms
have been distinguished ; first, those networks and trabec-
ulfe, developed from cells, which do not yield gelatin on
boiling, and, secondly, fibrillar connective tissue composed
of a gelatin-yielding substance. Of the first kind we notice
the following varieties :

1. Independent masses of gelatinous or mucous tissue,

13

194 THE MICROSCOPIST.

consisting of nucleated cells, giving off smooth anasto-
mosing trabeculee, as in the early stage of the vitreous
humor of the eye and of the gelatinous tissue of the um-
bilical cord, etc.

2. Very delicate reticular tissue found in the eye and in
the interior of nerve-centres.

3. A network filled with lymphoid cells (adenoid or
cytogenous tissue) in the glands of the lymphatic system,
and around the fasciculi of fihrillar connective tissue.

4. A coarser network in the ligamentum pectinatum
of the human eye.

5. A tissue formed of fusiform and stellate cells, as in
the interior of the kidneys

The second form referred to, or the fibrillar connective
tissue, was the only form to which the term connective
tissue was formerly applied. It is composed of gelatin-
yielding fibrillse, which may be split into skein-like por-
tions of various breadth. (Plate XIX, Fig. 146.) Per-
manganate of potash stains it brown. Acetic and dilute
mineral acids cause the tissue to swell so that the appear-
ance of fibrillation is lost through compression, and the
cells, or nuclei, are made manifest. Chloride of gold
staining exhibits both fibrillre and cells.

Elastic fibres (yellow elastic) (Plate XIX, Fig. 147) are
apparent in all forms of connective tissue which have been
made transparent by boiling, or acetic acid. They are
non-gelatinizing, cylindric, slightly branched, or forming
plexuses. In some fasciculi of fibrillar connective tissue, as
seen after the action of acetic acid, elastic fibres appear in
hoops, or spirals, around them. In the ligamentum nu-
cleae of the giraffe the elastic fibres are marked by trans-
verse striae, or cracks. Elastic fibres often form flattened
trabeculae, or are fused into elastic plates, or membranes,
with foraminae. as in arterial tunics.

The ligaments of the skeleton, the periosteum, peri-
chondrium, aponeuroses, fasciae, tendons, and generally all

THE MICROSCOPE IN ANIMAL HISTOLOGY. 195

the tunics of the body, afford examples of the fibrillar
connective tissue.

Fatty Tissue. — The loose connective tissue contains in
various parts great numbers of cells filled with fat. Their
form is round, or oval, and are often divided into groups,
or lobules, by trabeculse. (Plate XIX, Fig. 148.) Each
lobule has its own system of bloodvessels, which divide
into such numerous capillaries that the smaller groups,
and even individual fat-cells, are surrounded by vascular
loops. Sometimes the contents of the cells appear in*
needle-shaped crystals, often collected in a brush-like form.
Fat-cells seem to be chiefly receptacles for the deposit of
superabundant oleaginous nutriment, and are analogous
to the starch-cells in vegetables.

Cartilage. — This is formed of cells in an originally homo-
geneous intercellular substance. The only difference be-
tween what was formerly distinguished as cartilage and
fibre-cartilage is that the matrix or intercellular substance
of the latter is fibrous.

The cells, or cartilage-corpuscles, are nucleated, and lie
in cavities of various sizes and form in the matrix (Plate
XX, Fig. 149). Two nuclei often appear in one cell. It
is yet a question whether the capsule and matrix are the
secretion of the cells which has become solid, or a part of
the body of the cell which has undergone metamorphosis.

The multiplication of cartilage-cells is endogenous. By
segmentation, two, four, or a whole generation of daughter-
cells, so called, may lie in the interior of a capsule. In this
way growing cartilage may acquire a great number of
elements.

In the ear of the mouse, etc., wre observe a form of car-
tilage which is wholly cellular, and possesses no matrix
(Plate XX, Fig. 150).

Bone, or osseous tissue, is formed secondarily from meta-
morphosed descendants of cartilage or connective-tissue
cells, and is the most complex structure of this group. It

196 THE MICROSCOPIST.

consists essentially of stellate ramifying spaces containing
cells, and a hard, solid, intermediate substance. The latter
is composed of glutinous material rendered hard by a mix-
ture of inorganic salts, chiefly of calcium.

As all bones are moulded first in cartilage it was natural
to conceive that they were developed by a transformation
of cartilage. Much variety of opinion still exists respect-
ing the process, but it is generally conceded that although
cartilage may undergo calcification, true bone is not formed
until the cartilage is dissolved. New generations of stel-
late cells appear in a matrix, which is first soft and then
calcified. New bone may also grow from the periosteum
by means of a stratum of cells called osteoblasts. The de-
tails of the process are too extensive for a treatise like the
present. If sections of growing bone are decalcified with
chromic acid and treated with carmine, the osteoblastic
layers and adjacent youngest bony layer acquire an in-
tensely red color, while the rest of the tissue, except the
bone-corpuscles, remains uncolored.

Fine sections cut from a long bone longitudinally and
transversely will show the microscopic structure, consist-
ing of the Haver sian canals (Plate XX, Fig. 151, a] sur-
rounded with concentric lamellae of compact structure (6, b).
There are also intermediate and periosteal lamellae (c, d).
The cavities containing the bone-cells, or bioplasts (e, e,)
are of various sizes, from 0.0181 to 0.0514 millimetres
long, and from these lacunce run the canaliculi in an irregu-
lar radiating course (/,/)• In a balsam-mounted specimen
these hollows sometimes retain air, by which the structure
is rendered more apparent.

Dentine is the structure of which the teeth are most
largely composed. It consists of minute tubes filled with
bioplasm, which radiate from the central cavity of the
tooth, the interspaces between the tubes being solidified
by earthy salts so that the tissue is harder than bone.

Histologically a tooth may be said to be made of three

PLATE

FIG. 149.

'O

FIG. 150.

Cellular Cartilage of Mouse's Ear.

Section of the Branchial Cartilage of Tadpole.

^~^<£

Longitudinal and transverse section of Bone: — a, Haver-
sian canals; 6, concentric lamellae; c, intermediate; d,
periostial lamellae; e, bone-cells; /, canaliculi.

FIG. 152.

J? ".•,"'.; \>

Striated Muscular-fibre, separated into fibrillie

Vertical section of Human
Molar Tooth:— 1, enamel; 2,
cementumorcrustapetrosa ;
3, dentine, or ivory; 4, osse-
ous excrescence,arising from
hypertrophy of cementum ;
5, pulp-cavity; 6, osseous
lacunae at outer part of den-
tine- Involuntary Muscular-fibre

Sarcolemma.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 197

kinds of tissue: the cement, a bony substance, coating the
root of the tooth, containing bone-cells and canaliculi,but
no Haversian canals, the pulp in the central cavity of the
tooth serving for the nutrition of the organ, as a large
Haversian canal ; the dentine, or ivory, constructed as
above described; and the enamel, covering the crown, arid
consisting of columns or prisms, often hexagonal, which
are the hardest and densest structures of the body (Plate
XX, Fig. 152).

The development of enamel from epithelium has been
referred to on page 192. The dental germ corresponds to
a papilla of the mucous membrane, and in an early stage
is covered by delicate stratified cells — the dentine cells,
or odontoblasts — which produce dentine. Teeth are thus
produced abnormally in other situations besides the jaws,
as in ovarian cysts, etc.

Before the development of the 'first, or milk teeth, the
rudiments of the permanent teeth exist as a fold or leaf
of epithelium springing from the enamel germ.

II. COMPOUND TISSUES.

1. Muscle. — This is the tissue by which the principal
movements of the body are performed. It consists of
fibrin, which is endowed with special contractile power.
It is of two kinds, the voluntary, pertaining to organs of
voluntary motion, and the involuntary, found in situa-
tions which are not under the control of volition, as the
coats of bloodvessels, alimentary canal, uterus, and blad-
der. The fibres of voluntary muscles are marked with
transverse striae. Involuntary muscular fibres are smooth,
except in a few instances, as the fibres of the heart and
some of those in the oesophagus, which are striated.

The fibres are connected with and invested by connec-
tive tissue, and arranged in parallel sets, with vessels and
nerves in the intervals, and are attached to the parts they

198 THE MICROSCOPIST.

are designed to move by tendon, aponeuroses, or some form
of fibrous tissue. The organs or muscles thus formed are
generally solid and elongated, but sometimes expanded.

Involuntary or unstriped muscular fibres are flat bands
or spindle-shaped fibres with nuclei, which may be re-
garded as the remains of the formative bioplasm (Plate
XX, Fig. 153). They are usually transverse, or interlace
with each other on the walls of cavities and vessels. In
the heart the fibres, though involuntary, are striped and
branching. Striped fibre varies from g'0th to ^o^th inch
in diameter. It is largest in insects, in which individual
fibrils may be readily obtained, especially from the thoracic
muscles. They are generally found in bundles of fibrils,
splitting longitudinally or in disks, and each bundle is
inclosed in a sheath or sarcolemma (Plate XX, Fig. 154).

The transverse striation of muscle is subject to much
variation, and the precise nature of the sarcous elements
which produce the appearance is yet a matter of dispute,
but in all probability the ultimate elements are sarcous
prisms or particles imbedded in a homogeneous mass, and
by their mutual attraction, excited by various stimuli,
the contraction of the fibre takes place.

For the purpose of observation, the connective tissue
may be removed from muscular fibre by gelatinizing it
with dilute sulphuric acid, and dissolving it at a temper-
ature of 104° F. The nuclei of muscular fibre are seen
after treating with acetic acid, and may be stained with
carmine fluid, etc.

2. Nerve-tissue. — The term nerve was applied by the
ancients to tense cords, as bow-strings, musical strings,
etc., and was appropriated to the fibres now called nerves,
because they deemed them to operate by tremors, vibra-
tions, or oscillations, another instance of wrong naming
of structure from an opinion respecting function. Hip-
pocrates, Galen, and others, however, thought nerves were

THE MICROSCOPE IN ANIMAL HISTOLOGY. 199

hollow tubes, conveying fine ethereal fluids, termed ani-
mal spirits.

Nervous matter is soft, unctuous, and easily disturbed,
hence it is necessary to examine it while fresh. Histo-
logically it is divided into fibres and cells, imbedded in
connective tissue.

Nerve-fibres are of two kinds, the medullated, or dark-
bordered threads, and the pale, or non-medullated. Med-
ullated fibres consist of a delicate envelope of connective
tissue, called the neurilemma or primitive sheath, an axis-
cylinder or albuminous portion, extending down the cen-
tre, and a portion composed of a mixture of albumen,
cerebral matter, and fat, surrounding the axis-cylinder
(Plate XXI, Fig. 155, A, B, c). This latter is the medul-
lary sheath, or white substance of Schwann. It changes
rapidly, so as to coagulate and become granular. Alka-
lies render it fluid, so as to exude in fat-like drops. Ab-
solute alcohol, chromate of potass and collodion, contract
the sheath, so as to permit the axis-cylinder, which is the
essential part of the nerve, to protrude (Plate XXI, E,
Fig. 155). Anilin, carmine, nitrate of silver, and chloride
of gold stain the axis, while osmic acid blackens only the
medullary sheath.

Non-medullary or pale nerve-fibres are regarded as em-
bryonic or developmental forms (Plate XXI, D, Fig. 155).
The ganglionic fibres of the sympathetic (Remak's fibres)
are flat, homogeneous bands, with round or oval nuclei.
Some have considered them as formed of connective tis-
sue, but their nervous character is generally conceded.

Schultze and others regard the axis-cylinder as made up
of extremely delicate fibrillee.

. Nerve-cells, or ganglion corpuscles, are of two kinds,
those without and those with processes. The first are
called apolar, and the latter unipolar, bipolar, or multi-
polar, according to the number of ramifications. The
cells are nucleated, and inside the nucleus is usually

200 THE MICROSCOPIST.

another, the nucleolus. Dr. Beale discovered certain gan-
glion-cells in the sympathetic of the tree-frog (in the au-
ricular septum of the heart), one of whose poles is encir-
cled spirally by the others (Plate XXI, Fig. 156).
' The ultimate structure of ganglia or nervous knots,
and the relation of the fibres to the cells, opens a wide
field of research. In the muscle of the heart, etc., many
of these ganglia seem to form special nervous systems.
Dr. Beale has described the nerves ramifying on the capil-
laries and involuntary muscular fibrils of the terminal ar-
teries as a self-regulating mechanism for the distribution
of blood (Plate XXI, Fig. 157). Thus, if a tissue receives
excess of pabulum, the capillary nerve-fibre is disturbed
and transmits a change to the ganglion, and thence
through the efferent nerve to the muscular fibres of the
artery, and vice versa.

Meissner has shown many ganglionic plexuses in the
submucous coat of the alimentary canal. Another system
of the same kind, called the plexus myeniericus, was dis-
covered by Auerbach between the muscular layers of the
intestinal tube. Similar plexuses exist in other organs.

As to the peripheral termination of nerve-fibres, there
is still considerable discussion. Most of the German his-
tologists consider the nerves of voluntary muscles to ter-
minate in end plates, in which the neurilemma becomes
continuous with the sarcolemma of the muscular fibre.
Dr. Beale maintains that there is a plexus of minute nerves
over the fibrils. In some of my own preparations, espe-
cially some stained with soluble Prussian blue, a disk
formed of a plexus of excessively minute nerve-fibres is
observed, from which tortuous branches go to other mus-
cle-fibres.

In the cornea, Cohnheim and Klein have traced fine
nerve-fibres to the epithelial cells of the conjunctiva, by
means of chloride of gold staining.

3. Glandular tissue consists of a fine transparent mem-

PLATE XXI.

FIG. 155.

FIG. 156.

\

Various Ganglionic Nerve-cells.

FIG. 157

Nerve-fibres.

Self-regulating System of Ganglia — nerves,
arteries, and capillaries.

Glandular Tissue.

FIG. 160.

Layers of Blastoderm.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 201

brane, through which the plasma transudes, and cells of
glandular epithelium. A vascular network exists on the
surface of the membrane, from which the material of the
secretion is obtained. This membrane may be a simple
follicle, or tube, as in the mucous membrane, or system of
tubes, as in the kidneys, a convoluted tube, a simple open
vesicle, a racemose aggregation of vesicles, or a close cap-
sule which discharges itself by bursting. (Plate XXI,
Fig. 158).

4. Vascular Tissue. — The smallest bloodvessels and lym-
phatics, called capillaries, are minute tubes, consisting of a
series of flattened epithelial cells, and containing stomata,
or openings through which white or red blood-corpuscles
may occasionally pass (Plate XX, Fig. 159, a, b). The
larger trunks have, in addition to the cellular layer, one
of longitudinally striated connective tissue, a middle coat
containing transverse muscular fibres, and an external coat
of connective tissue (Plate XXI, Fig. 159). The distribu-
tion of the capillary bloodvessels is various, according to
the nature or function of the organ or tissue in which they
are found.

DEVELOPMENT OF THE TISSUES.

It has been stated, page 125, that reproduction in the
higher animals consists of an ovum fecundated by contact
with a sperm-cell, or spermatozoid. The ovum consists
of a germinal vesicle, containing one or more germinal spots,
and included within a vitellus (a yelk) which is surrounded
by bvitelline membrane, which may have additional invest-
ments in the form of layers of albumen and of an outer
coriaceous or calcified shell.

The first step in the development of the embryo is the
division of the vitelline substance into cleavage-masses, at
first two, then four, then eight, etc. This process of yelk-
division may affect the whole yelk or a part of it, and re-
sults in the formation of a blastoderm, or embryogenic

202 THE MICROSCOPIST.

tissue. This rudimentary embryonic tissue consists of
three layers of cells, or germinal plates. The upper is the
corneous layer, or epiblast, the middle one the intermediate
plate, or mesoblast, and the lower the intestinal glandular
layer, or hypoblast (Plate XXI, Fig. 160). From these
the various tissues and organs are developed.

The outer plate produces the epithelium of the skin and
its appendages, with the cellular elements of the glands of
the skin, mammae, and lachrymal organs. By a peculiar
folding over the axis this plate also produces the elements
of the brain and spinal cord, and the internal parts of the
organs of special sense. The physiological significance of
this layer is, therefore, very great.

The lower stratum of the blastoderm supplies the epi-
thelium of the digestive tract, and the cellular constituents
of its various glands, together with the liver, lungs, and
pancreas.

The middle layer supplies the material for many struc-
tures. The whole group of connective substances, or
tissues of support; muscular tissue; blood and lymph,
with their containing vessels ; lymph-glands, including
the spleen, etc., all arise from this. The epithelial cells
of such tubes and cavities as originate in this layer are
regarded as different from those of true glands, and are
more permeable to fluids. They have been termed false
epithelium, or endothelium.

The following description, by Professor Huxley, will
enable the student to form an idea of the general process
of development. A linear depression, the primitive groove,
makes its appearance on the surface of the blastoderm,
arid the substance of the mesoblast along each side of this
groove grows up, carrying with it the superjacent epiblast.
Thus are produced the two dorsal lamince, the free edges
of which arch over toward one another, and eventually
unite, so as to convert the primitive groove into the cere-
bro-spinal canal. The portion of the epiblast which lines

THE MICROSCOPE IN ANIMAL HISTOLOGY. 203

this, cut off from the rest, becomes thickened, and takes
on the structure of the brain, or encephalon, in the region
of the head ; and of the spinal cord, or myelon, in the
region of the spine. The rest of the epiblast is converted
into the epidermis.

The part of the blastoderm which lies external to the
dorsal laminae forms the ventral lamince; and these bend
downward and inward, at a short distance on either side
of the dorsal tube, to become the walls of a ventral or
visceral tube. The ventral laminae carry the epiblast on
their outer surfaces, and the hypoblast on their inner sur-
faces, and thus, in most cases, tend to constrict off the
central from the peripheral portions of the blastoderm.
The latter, extending over the yelk, incloses it in a kind
of bag. This bag is the first formed and the most con-
stant of the temporary, or fostal appendages of the young
vertebrate, the umbilical vesicle.

While these changes are occurring, the mesoblast splits,
throughout the regions of the thorax and abdomen, from
its ventral margin, nearly up to the notochord (which has
been developed, in the meanwhile, by histological differen-
tiation of the axial indifferent tissue, immediately under
the floor of the primitive groove) into two lamella. One
of these, the visceral lamella, remains closely adherent to
the hypoblast, forming with it the splanchnopleure, and
eventually becomes the proper wall of the enteric canal ;
while the other, the parietal lamella, follows the epiblast,
forming with it the somatopleure, which is converted into
the parietes of the thorax and abdomen. The point of
the middle line of the abdomen at which the somato-
pleures eventually unite, is the umbilicus.

The walls of the cavity formed by the splitting of the
ventral laminae acquire an epithelial lining, and become
the great pleuroperitoneal serous membranes (Huxley's
Anatomy of Vertebraled Animals).

In addition to the umbilical vesicle, above described as

204 THE MICROSCOPIST.

a temporary appendage, the foetus has other special struc-
tures, derived from the blastoderm. Thus the somato-
pleure grows up over the embryo arid forms a sac filled
with clear fluid, the amnion. The outer layer of the sac
coalesces with the vitelline membrane to form the chorion.
The attantois begins as an outgrowth from the mesoblast.
It becomes a vesicle, and receives the ducts of the primor-
dial kidneys or Wolffian bodies, and is supplied with blood
from the two hypogastric arteries which spring from the
aorta. The allantois is afterwards cast off by the contrac-
tion of its pedicle, but a part of its root is usually re-
tained, and becomes the permanent urinary bladder. In
the Mammalia the allantois conveys the embryonic ves-
sels to the internal surface of the chorion, whence they
draw supplies from the vascular lining of the uterus.

Foster and Balfour recommend that the study of em-
bryonic development should commence with the egg of a
fowl taken at different times from a brooding hen, or an
artificial incubator. The egg should be placed on a hol-
low mould of lead in a basin, and covered with a warm
solution of salt (7.5 per cent.). It should be opened with
a blow, or by filing the shell. With the naked eye or
simple lens, lying across the long axis of the egg, may be
seen the pellucid area, in which the embryo appears as a
white streak. The mottled vascular area, with the blood-
vessels, and the opaque area spreading over the yelk, may
be observed. The blastoderm may be cut out with a sharp
pair of fine scissors, floated into a watch-glass, freed from
vitelline membrane and yelk, and removed (under the salt
solution) to a glass slide. A thin ring of putty may then
be placed round the blastoderm, which is covered with
salt solution, and the thin glass cover put on. With a
low-power objective many of the details of structure may
be seen in an embryo of thirty-six to forty-eight hours
incubation, as the heart, the neural tube, the first cere-

THE MICROSCOPE IN ANIMAL HISTOLOGY. 205

bral vesicles, the folds of the somatopleure and splanch-
nopleure, the provertebne, etc.

To prepare sections of the embryo, it must be first hard-
ened by placing the slide containing it in a solution of 1
per cent, chromic acid for twenty-four hours. From this
it should be removed to one of 3 per cent, for twenty -four
hours more ; then for a similar time in alcohol of 70 per
cent., then in alcohol of 90 per cent., and lastly in abso-
lute alcohol, where it may remain till required for section.
Sometimes picric or osmic acid is used for hardening.
The embryo may be stained by placing it in Beale's car-
mine fluid for twenty-four hours, and then replacing it in
absolute alcohol for a day before it is cut. It may also
be stained with hsematoxylin if preferred. The specimen
may be imbedded in paraffin, wax, and oil, or a mixture
of four parts of spermaceti to one part of cocoa butter or
castor oil. If there are cavities in the object, it is best
to saturate it first with oil of bergamot. A little melted
spermaceti mixture is poured on the bottom of a small
paper box, and when solid the embryo is placed flat on
it, the superfluous oil removed as far as possible, and the
warm mixture poured on. Bubbles can be removed with
a hot needle. A mark should be made of the exact posi-
tion of the embryo. Sections may be cut with the sec-
tion-cutter or a sharp razor, and if the spermaceti mix-
ture is used, the razor should be moistened with olive oil.
The sections should be floated from the razor to the slide,
and treated with a mixture of four parts turpentine and
one of creasote. They may then be mounted in balsam
or dammar varnish.

The most instructive transverse sections of an early
embryo will be through the optic vesicles, the hind brain,
the middle of the heart, the point of divergence of the
splanchnopleure folds, the dorsal region, and a point where
the medullary canal is still open. For the unincubated
blastoderm only one section, through the centre, is re-

206 THE MICROSCOPIST.

quired to show the formative layers. In the later stages
dissection is required, and is best performed with embryo
preserved in spirit. If living embryos are placed in spirit,
a natural injection of the vessels may be obtained.

III. OKGAKS OF THE BODY.

Anatomists usually group the organs into systems, as
the osseous, muscular, nervous, vascular systems, etc., but
for histological study a classification based on physiologi-
cal considerations may be more convenient for the student.

I. VEGETATIVE ORGANS.

1. Nutritive, or organs pertaining to the absorption and
distribution of pabulum, including the digestive and cir-
culatory organs.

The mucous membrane of the intestinal canal contains
many follicles and glands, whose secretions serve impor-
tant offices in the preparation of the food. These will be
referred to in the next section. The epithelium of the
intestinal canal is columnar, except in the oesophagus,
where it is laminated. Beneath the glandular layer of
the stomach is a stratum of fibrous connective tissue and
muscle fibres in two layers, an internal with transverse,
and an external with longitudinal fibres. The tissue of
the small intestine beneath the epithelium is reticular
connective, entangling lymphoid cells. The structure of
the large intestine is similar to that of the stomach. The
villi of the small intestine begins at the pylorus, flat and
low at first, but becoming conical, and finally finger-like
in shape. The epithelium of the villi are columnar, with
a thickened and perforated edge (Plate XXII, Fig. 161).
Between the epithelial cells of the villi, peculiar "goblet-
cells" are often found, which Frey supposes to be decay-
ing cells. The reticular connective tissue of each villus
is traversed by a vascular network, a lymphatic canal or
lacteal, and delicate longitudinal muscular fibres. If the

THE MICROSCOPE IN ANIMAL HISTOLOGY. ; 207

villus is unusually broad, there may be more than one
lacteal. The lacteals absorb the fluid known as chyle.
They are blind ducts, and nitrate of silver injections show
them to have the same structure as other lymphatics.

The lymphatic radicles are widely disseminated through
all the tissues and organs of the body. They take up nu-
tritive fluids, either from the alimentary canal, or such as
have transuded from the capillaries into the interstices of
the body, mingled with the products of decomposition,
and convey them into the general circulation. Hyrtl's
method of demonstrating these radicles is by passing a
fine canula into the tissue containing lymphatics and forc-
ing the injection by gentle pressure. They are either net-
works, analogous to capillaries, or blind passages which
unite in reticulations. The structure of the vessels has
already been described, page 201. Lymphatics and capil-
laries do not communicate directly. A lymph-canal may
be surrounded by capillaries, or run alongside of a capil-
lary, or a lymphatic sheath may envelop a bloodvessel.
This latter plan is seen in the nervous centres, and has
been called by His the perivascular canal system.

The larger lymphatic trunks are interrupted by nodular
and very vascular organs, the lymphatic glands. These
consist of the reticular connective tissue already described,
surrounded by an envelope of ordinary fibrous tissue. One
or more afferent lymphatic vessels penetrate the capsule,
or envelope, and similar efferent vessels make their exit
from the other side. Frey describes these glands as con-
sisting of a cortical portion, follicles, and a medullary
portion composed of the tubes and reticular prolongations
of the follicles (Plate XXII, Fig. 1«2). There is a corn-
plicate system of communication between the follicles.
The afferent vessel opens into the investing spaces of the
follicle. These lead into the lymph-passages of the med-
ullary portion, from the confluence of which the radicles
of the efferent vessels are formed. The lingual follicular

208 THE MICROSCOPIST.

glands and tonsils, the solitary and agminated glands of
the intestine (Peyer's patches), the thymus, and the spleen
have a similar structure, and are called lymphoid organs.

In the thoracic duct the epithelium is inclosed in several
layers of fibrous membrane. The latter contains trans-
verse muscular fibres. The heart, although an involuntary
muscular organ, has striated muscular fibres. These fibres
are not, like other striped muscles, collected into bundles,
but are reticular. The heart, like other organs, is supplied
with lymphatics and bloodvessels. The cardiac plexus of
nerves consists of branches from the vagus and sympa-
thetic. Numerous microscopic nervous ganglia also occur,
especially near the transverse groove and septum of the
ventricles. It is thought that these are the chief centres
of energy, so that the heart pulsates after its removal from
the body. It has also been shown recently that the sym
pathetic and vagus filaments are in antagonism, so that
stimulation of the vagus interrupts the motor influence of
the sympathetic, and may bring the heart to a standstill
in a condition of diastole.

The structure of bloodvessels has been described under
the head of vascular tissue. JSTo special boundary exists
between capillaries and the arteries and veins. The ar-
rangement of the capillaries, however, is various, and
often so characteristic that a practiced eye can generally
recognize an organ or tissue from its injected capillaries.
(Plate XXII, Figs. 163 to 1G8.) For methods of inject-
ing, see page 64. Capillaries form either longitudinal or
rounded meshes. The muscular network, etc., is extended,
while fat-cells, the alveoli of the lungs, lobules of liver,
capillary loops of papillae in skin and mucous membranes,
outlets of follicles, etc., present a more or less circular in-
terlacement. The capillary tube lies external to the ele-
mentary structure, and never penetrates its interior.

2. Secretive Organs. — True secretions serve important
offices in the organism : as the materials of reproduction ;

PLATE XXII.

FIG. 161.

FIG. 162.

Intestinal Villas.

FIG. 163.

Lymphatic Gland.
FIG. 164.

Capillary net-work around Fat-cells.
FIG. 165.

Capillary net-work of Muscle.
Via. 166.

Distribution of Capillaries
in Mucous Membrane.

FIG. 167.

Distribution of Capillary bloodvessels
in Skin of Finger.

FlG. 168.

Villi of Small Intestine of Monkey.

Arrangement of the Capillaries of the air-cells of
the Human Lung.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 209

milk from the mammary gland; saliva, gastric juice and
pancreatic fluid for digestion ; mucus, sebaceous matter,
tears, etc. Excretions result from waste or decomposi-
tion, and are incapable of further use; as carbonic acid,
separated by the lungs ; urea, uric acid, etc., by the kid-
neys ; saline matters, from kidneys and skin ; lactic acid,
portions of bile, and some of the components of faeces.

The sweat glands in the skin are simply convoluted tubes
lined with glandular epithelium and surrounded by a
basket-like plexus of capillaries. The sebaceous glands are
racemose, and often open into the hair-follicles.

The salivary glands are complex mucous glands, anc}
the saliva secreted by them is a complex mixture. The
terminal nerves of the submaxillary gland have been traced
to the nuclei of the gland-cells.

The lingual glands, and parotid, partake of the nature
of lymphoid organs. The glands of the oesophagus are
racemose. In the stomach there are two kinds, the peptic,
and gastric mucous glands. The peptic glands are blind
tubes closely crowded together over the mucous mem-
brane, lined with columnar epithelium near their open-
ings, and gland-cells below. The mucous glands are nu-
merous near the pylorus, and are usually branching tubes.
The capillaries are arranged in long rneshes about the
peptic glands, and form a delicate network in the submu-
cous tissue. Numerous lymphatic radicles communicate
with lymph-vessels below the peptic glands.

The small intestine contains the racemose glands of
Brunner and the tubular follicles of Lieberkuhn, together
with the lymphoid follicles known as the solitary and
agminated glands of Peyer. The glands of Brunner are
confined to the duodenum, and their excretory duct and
gland vesicle are lined by columnar epithelium. Lieber-
kuhn's follicles are found in great numbers all over the
small intestine. Peyer's patches are most numerous in
the ileum. They are accumulations of solitary glands,

14

210 THE MICROSCOPIST.

and their structure is similar to the follicles of a lymphatic
gland. The gland vesicles of the pancreas are roundish,
and like other salivary glands it is invested with a vascu-
lar network with rounded meshes.

The liver is the largest gland connected with nutrition.
Few animals are without a liver or its structural equiva-
lent. In polyps the liver is represented by colored cells
in the walls of the stomach cavity. In annelids the biliary
cells cluster round ceecal prolongations of the digestive
cavity. In Crustacea the liver consists of follicles, and in
insects of tubes, opening into the intestine. In all cases
the essential elements are glandular cells containing col-
oring matter, oil, etc. In vertebrates some parts of the
structure have not been decided upon without controversy.

In man the liver is a large, solid, reddish-brown gland,
about twelve inches across, and six or seven inches from
anterior to posterior edge, and weighing three or four
pounds, situated in the right hypochondrium, and reach-
ing over to the left. It is divisible into right and left
lobes by the broad peritoneal ligament above, and the
longitudinal fissure beneath. From the latter a groove
passes transversely on the right side, lodging the biliary
ducts, sinus of the portal vein, hepatic artery, lymphatics,
and nerves, which are enveloped in areolar tissue, called
the capsule of Glisson. From this groove ramifications
of the portal canal extend through the liver, so numerous
that no part of the hepatic substance is further than one-
thirtieth of an inch from them. These ramifications
carry the branches of the portal vein from which the
capillary plexus surrounding the lobules begin, together
with the bile-ducts, hepatic artery, etc.

The hepatic lobules are readily distinguished by the
naked eye in many mammals, as the hog, but less easily
in human liver. They consist essentially of innumerable
gland-cells, and a complex network of vessels which tend
towards the centre of the lobule, where their confluence

PLATE XXIII.

Fio. 169.

FIG. 170.

Lobule of Liver.

FIG. 171.

Uriniferous Tubes of Kidney.

FIG. 173.

Blood-vessels of Kidney.

Tactile Papillse.

FIG. 174.

FIG. 172.

Alveoli of Lung.

Taste-buds.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 211

forms the radicle of the hepatic vein ; while externally
the lobules are bounded by branches of the portal vein
and biliary canals (Plate XXIII, Fig. 169). The hepatic
artery nourishes the proper connective tissue of the organ,,
and its venous radicles return the blood to the portal
vein. The liver or bile-cells lie between the meshes of
the capillaries, and are irregularly polyhedral from pres-
sure, soft, granular, and nucleated. Brown pigment-graiv
ules and fatty globules are also found in the cells, and in*
disease in increased quantity. These bile-cells are inclosed
in a delicate reticulated membrane, and Hering considers-
them to have a plexus of fine bile-ducts around them.

The kidneys are two large bean-shaped organs, each
covered with a thin but strong fibrous envelope or tunic,
which is continuous round the organ to the hilus, where
the ureter leaves the gland and the bloodvessels enter.
Even with the naked eye we may distinguish in a section
of kidney the external granular cortex and the fibrous or
striped medullary portion. The lines of the latter con-
verge towards the hilus, and generally in a single conoid
mass ; but in man and some other animals this is divided
into sections, called the pyramids, and between them the
cortical substance is prolonged in the form of septse, while
both portions contain interstitial connective tissue. Both
the cortical and medullary portions contain long branch-
ing glandular tubes, called the uriniferous tubes. In the
medullary part these tubes are straight and divide at
acute angles, while in the cortex they are greatly convo-
luted and terminate in blind dilatations, the capsules of
Bowman. Staining with nitrate of silver shows the cap-
sules to be lined with delicate pavement-epithelium. The
convoluted tubes proceeding from the capsules, containing
thick granular gland-cells, after numerous windings in the
cortex, arrive at the medullary portion, where each pur-
sues a straight course, and is lined with flat pavement-
epithelium similar to the endothelium of vascular tissue.

212 THE MICROSCOPIST.

the base of the pyramids these tubes curve upwards,
forming the looped tubes of Henle. The recurrent tubes
enlarge, and exhibit the ordinary cubical gland-cell.
These tubes also become more tortuous, and empty into
others of larger calibre, called collecting tubes. These
are lined with low columnar epithelium, and uniting with
similar tubes at acute angles, give exit to the urine at the
apex of the papillae in the pyramids (Plate XXIII, Fig.
170).

The bloodvessels of the kidney are as complex as the
glandular tissue. Both vein and artery enter at the hilus
of the kidney, and after giving twigs to the external
tunic, proceed between the pyramids as far as their bases.
Here they give off curving branches, forming imperfect
arches among the arteries, and complete anastomosing
rings on the veins. From the arterial arcbes spring the
branches which bear the glomeruli of the cortical sub-
stance or Malpighian tufts (Plate XXIII, a, Fig. 171).
The afferent vessel of the glomerulus subdivides, and after
coiling and twisting w7ithin the capsule of Bowman, gives
origin to the efferent vessel, by the union of the small
branches thus formed. This efferent vessel breaks up into
a network of fine capillaries, with elongated meshes sur-
rounding the straight uriniferous canals. From the periph-
ery of this network somewhat wider tubes are given off,
which surround with rounded meshes the convoluted tubes
of the cortex.

The long bundles of vessels between the uriniferous tubes
of the medulla, communicating in loops or forming a deli-
cate network round the mouths of the canals at the apex
of the papillse are called the vasa recta.

The ureters, like the pelvis of the kidney, consist of an
external fibrous tunic, a middle layer of smooth muscular
fibres, and an internal mucous membrane with a layer of
epithelium. The bladder is covered externally with a
serous membrane, the peritoneum. The female urethra is

THE MICROSCOPE IN ANIMAL HISTOLOGY. 213

lined by mucous membrane, with vascular walls full of
folds, and containing, near the bladder, a number of mu-
cous glands.

3. Respiratory Organs. — The lungs receive air by the
trachea and venous blood from the right side of the heart
to transmit to the left side. They may be compared, as
to form and development, to racemose glands. The ex-
cretory ducts are represented by the bronchial ramifica-
tions, and the acini by the air-vesicles.

The ciliated mucous membrane of the bronchial twigs
gradually loses its laminated structure until only a single
layer remains. Their muscular layer also ceases before
arriving at the air-cells. At the end of the last bronchial
tubules we find thin-walled canals called alveolar passages.
These are again subdivided and end in peculiar dilatations
called primary pulmonary lobules, or infandibula (Plate
XXIII, Fig. 172). The air-cells, vesicles, or alveoli, are
sacciilar dilatations in the walls of the primary lobules,
opening directly into a common cavity. Their walls con-
sist of delicate membrane of connective tissue, often con-
taining black pigment, probably from inhalation of car-
bonaceous matter, or a deposit of melanin.

The pulmonary artery subdivides, and follows the rami-
fications of the bronchi to the pulmonary vesicles. Here
a multitude of capillary tubes form a network over the
alveoli, only separated from the air by the most delicate
membrane (Plate XXII, Fig. 168). In the frog we find
the whole respiratory portion lined with a continuous
layer of flattened epithelia. A similar lining is found in
the mammalian foetus, but in the adult the number and
character of the epithelial scales is greatly changed. Large
non-nucleated plates are seen with occasional traces of the
original bioplasm. In inflammatory affections, however,
these may multiply, giving rise to catarrhal desquamation.

4. G-enerative Organs. — The histology of the organs of
reproduction is quite elaborate, and the plan of this work

214 THE MICROSCOPIST.

only permits us to glance at the essential structures,
which are the seminiferous tubules for the secretion of
spermatozoa, in the male, and the ovary for the production
of the germ, or ovum, in the female.

The tubuli seminiferi are a multitude of fine and tortuous
tubules contained in the testis, with its accessory epididy-
mis. They lie in the interstices of sustentacular connec-
tive tissue, and consist of membranous tubes filled with
cells, which are said to possess amoeboid motion. During
the virile period these glandular tubes generate the sper-
matozoa, or microscopic seminal filaments. The shape of
these spermatozoa is filiform in all animals, but vary in
different species. In man they consist of an anterior oval
portion, or head, and a posterior flexible filament, or tail.
Different observers have taken different views as to the
origin of these structures. Some suppose them the product
of special cells, others trace them to the nuclei of the
glandular epithelium, while others regard them as ciliated
elements formed by the metamorphosis of entire cells.
Their motions baffle all attempts at explanation, although
quite similar to those of ciliated epithelium. The sperma-
tozoa penetrate by their movements into the interior of
the ovum, in order to impregnate it, and in the mammalia
in considerable numbers.

The ovary may be divided into two portions : a medul-
lary substance, which is a non-glandular and very vascular
connective tissue, and a glandular parenchyma enveloping
the latter. • The surface of the ovary uncovered by peri-
toneum is coated with a layer of low columnar cells, called
the germinal epithelium. Immediately under this is a
stratum called the zone of the primordial follicles, or cor-
tical zone. Here the young ova lie crowded in layers.
They consist of granular bioplasm, containing fatty mol-
ecules and a spherical nucleus. They are probably de-
veloped by a folding in of the germinal epithelium. To-
ward the internal portion of the ovary the follicles become

THE MICROSCOPE IN ANIMAL HISTOLOGY. 215

more highly developed, and the ovum contained in them is
also increased in size and enveloped in a distinct mem-
brane. There are from twelve to twenty mature follicles
in the ovarium, named, from their discoverer, Graafian
follicles. Each has an epithelial lining, in which the ovum
is imbedded. The capsule of the ovum is known as the
zona pellucida, or chorion, and the albuminous cell-body is
the vitellus. The nucleus is situated excentrically, and is
called the vesicula germinativa, or germinal vesicle of Pur-
kinje. "Within it is a round and highly refractive nucle-
olus, the macula germinativa, or germinal spot of Wagner.
A Graafian vesicle bursts and an ovum is liberated at
every menstrual period. During the progress of the latter
down the Fallopian tube to the uterus, impregnation may
take place by the penetration of spermatozoa into its yelk.
Then the inherent vital energies of the cell are aroused,
and the process of segmentation begins. Unimpregnated
ova are destroyed by solution. The ruptured and emptied
Graafian vesicle becomes filled up with cicatricial connec-
tive tissue, which constitutes what is called the corpus
luteum, after which it gradually disappears.

II. ORGANS OF ANIMAL LIFE.

1. Locomotive. — The microscopic structure of bone and
muscle has been described in connection with elementary
tissues. Tendons and fascias belong to the connective
tissues.

2. Sensory. — The nervous apparatus of the body, whose
histological elements were treated of on a previous page,
has been classified physiologically into:

1. The sympathetic system, consisting of a chain of gan-
glia on each side of the vertebral column, with commu-
nicating cords or extensions of ganglia, visceral nerves,
arterial nerves, and nerves of communication with the
cerebral and spinal nerves. The chief structural differ-

21(3 THE MICROSCOPIST.

ence between tins and the cerebro-spinal system is that in
the latter the nerve-cells form large masses, and the union
of its parts is effected by means of central fibres, while in
the sympathetic the cells are more widely separated, and
union between them and with the cerebro-spinal axis is
by means of peripheral fibres. The sympathetic is con-
sidered a motor and sensitive nerve to internal viscera,
and to govern the actions of bloodvessels and glands.

2. The cerebro-spinal system, divided into :

(1.) A system of ganglia subservient to reflex actions,
the most important of which is the spinal cord, where the
gray or vesicular nervous matter forms a continuous tract
internally.

(2.) A ganglionic centre for respiration, mastication,
deglutition, etc., writh a series of ganglia in connection
with the organs of special sense: the medulla oblongata,
with its neighboring structures; the mesocephalon, cor-
pora striata, and optic thalami.

(3.) The cerebellum, a sort of offshoot from the upper
extremity of the medulla, for adjusting and combining
voluntary motions.

(4.) The cerebrum, cerebral hemispheres, or ganglia,
which are regarded as the principal organs of voluntary
movements. In the lower vertebrates the hemispheres
are comparatively small, so as not to overlap the other
divisions of the brain ; but in the higher Mammalia they
extend over the olfactory lobes and backward over the
optic lobes and cerebellum, so as to cover these parts,
while they also extend downward toward the base of the
brain. In the lower vertebrates,' also, the surface of the
hemispheres is smooth, while in the higher it is compli-
cated by ridges and furrows.

(5.) The cerebral and spinal nerves. The spinal nerves
arise in pairs, generally corresponding with the vertebrae.
Each has two roots, one from the dorsal, and one from
the ventral region of its half of the cord. The former

THE MICROSCOPE IN ANIMAL HISTOLOGY. 217

root has a ganglionic enlargement, and contains only sen-
sory fibres ; the latter has no ganglion, and contains only
motor fibres.

The cerebral nerves are those given off from the base
of the brain. Some of these minister to special sensation,
as the olfactory, optic, auditory, part of the glosso-pha-
ryngeal, and the lingual branch of the trifacial nerves.
Some are nerves of motion, as the motor oculi, patheti-
cus, part of the third branch of the fifth pair, the abdu-
cens, the facial and the hypoglossal nerves. Others are
nerves of common sensation, as the fifth, and part of the
glosso-pharyrigeal nerves. Others, again, are mixed, as
the pneurnogastric and spinal accessory nerves.

The minute structure of the central organs of the ner-
vous system is excessively complicate and full of details.
Hardening with chromic acid and bichromate of potash
is generally advisable before examination. This should
be done with small pieces in a large quantity of the fluid.
One-eighth to one-half grain of bichromate, or 0.033 to
0.1 grain of chromic acid, to the ounce of water should
be used, the strength gradually increased from day to
day. After such maceration for several days, a drop of a
28 per cent, solution of caustic potash may be added to
one ounce of water, and the specimen soaked in it for an
hour, to macerate the connective tissue. After again soak-
ing in graduated solutions of the bichromate, up to two
grains to the ounce, the tissue may be carefully picked
apart under the dissecting microscope. In such manner
Deiters discovered the two kinds of processes in the multi-
polar ganglion-cells. Gerlach placed thin sections for two
or three days in 0.01 to 0.02 per cent, solutions of bichro-
mate of ammonia, and picked them apart after staining
with carmine.

Lockhart Clarke placed parts of the spinal cord in equal
parts of alcohol and water for a day, then for several days
in pure alcohol, till thin sections could be made. These

218 THE MICROSCOPIST.

were immersed for an hour or two in a mixture of one part
acetic acid and three parts alcohol, to render the gray
matter transparent and the fibrous elements prominent.

Sections may he stained with carmine and mounted in
glycerin or balsam (see Chapter Y).

(6.) Organs of special sense :

a. Organs of Touch. — The tactile papillae of the skin
and Pacinian corpuscles may be studied in thin sections
of fresh or dried skin. Treatment with dilute acetic
acid, or acetic acid and alcohol, and staini-ng with car-
mine, or chloride of gold, is recommended. The papillae
are made up of connective tissue, into which nervous fila-
ments enter, and end in peculiar tactile corpuscles (Plate
XXIII, Fig. 173). The structure of the skin itself, with
its various layers and sudoriparous glands, may be seen
in such sections.

b. Organs of Taste.— The terminations of the gustatory
nerves of the tongue are yet imperfectly known. In the
circumvallate papillae, on the side walls, certain structures
are found, called gustatory buds or taste-cups (Plate XXIII,
Fig. 174). They consist of flattened lanceolate-cells, ar-
ranged like the leaves of a flower-bud, and containing
within them fusiform gustatory cells, which end in rods,
and filaments projecting from the rods above the buds
are seen in some animals. Underneath is a plexus of pale
and medullated nerve-fibres. The mode .of nervous ter-
mination in the fungiform papillae is not known. For pri-
mary examination, sections of the dried tongue may be
softened in dilute acetic acid and glycerin, or hardened in
osmic acid. For the finer structure, maceration in iodine
serum, and immersion in one-half per cent, chromic acid,
with an equal quantity of glycerin, is recommended.
Careful picking under the simple microscope is necessary.
Sections may also be stained with chloride of gold.

c. Organs of Smell. — In the olfactory regions, which are
patches of yellowish or brownish color on the upper and

THE MICROSCOPE IN ANIMAL HISTOLOGY. 219

deeper part of the nasal cavity, we find nucleated cylin-
drical cells taking the place of ordinary ciliated epithe-
lium, and sending processes downward, which communi-
cate with each other, forming a delicate network (Plate
XXIV, Fig. 175). Between these cells we find the olfac-
tory cells, spindle-shaped nucleated bodies, extending up-
ward into a fine rod and downward into a varicose fila-
ment. In hirds and amphibia these rods are terminated
by delicate hairs, some of which have ciliary motion.
Beneath these structures are peculiar glands, consisting
of pigmented gland-cells. They are called Bowman's
glands. The branches of the olfactory nerve proceed be-
tween these glands and branch out into fine varicose fila-
ments, which are supposed to communicate with the
olfactory cells. Hardening in chromic acid, or Muller's
fluid, or a concentrated solution of oxalic acid, or one-
half to one per cent, solution of sulphuric acid, is neces-
sary for the preservation of these delicate structures.

d. Organs of Sight. — As in the sense of touch certain
tactile papillae detect deviations from the general surface ;
and in that of taste special rod-like end organs and their
covering bulbs distinguish the solutions of different sapid
substances ; and as in smelling, not the whole organ but
olfactory regions, with peculiar cells and nervous rods,
discriminate mechanical or chemical odors, so in vision a
special apparatus is provided to perceive the wonderful
variety of colors and forms. The minute structure of
organs becomes more complex in proportion as they serve
the higher functions of mind.

The various tunics and accessory structures of the eye
are described in most text-books ; we here limit ourselves
to a brief reference to those refracting and receptive struc-
tures whose office it is to translate the phenomena of light
into those of nervous conduction.

Externally, we have in front of the eye the transparent
cornea. This is made of connective tissue with cells, bun-

220 THE MICROSCOPIST.

dies of fibres, and cavities containing cells. Its tissues are
in layers, as follows : 1. External epithelium, flat and
laminated. 2. Anterior basement-membrane or lamina.
3. True corneal tissue. 4. Membrane of Descemet or
Demours. 5. Endotbelium witb flat cells (Plate XXIY,
Fig. 176). The cells of corneal tissue are of two forms.
The first are wandering or amoeboid cells, and may be
seen in a freshly extirpated frog's cornea placed underside
up, with aqueous humor in a moist chamber, on the stage
of the microscope. If a small incision be made at the
margin of the cornea of a living frog a few hours before
its extraction, and vermilion, carmine, or anilin blue is
rubbed in, the cells which have absorbed the coloring
matter will be found at some distance afterwards, having
wandered like leucocytes or pus-cells elsewhere. Their
origin may be from blood or true corneal corpuscles, or
both. The second form, or corneal corpuscles, are im-
movable, flat, with branching or stellate processes. They
may be demonstrated by staining with chloride of gold
or nitrate of silver. The bundles of fibrillar substance in
the cornea pass in various directions, and the natural
cavities in it contain the corneal cells. As stated, the
nerves of the cornea have been traced to the external
epithelium, which sometimes contains serrated (riff or
stachell) cells.

The aqueous humor is structureless, but the vitreous
humor is supposed to have delicate membranous septa.
The crystalline lens consists of a capsule inclosing a tissue
of fine transparent fibres or tubules, which are of epithe-
lial origin. These fibres are flat, and often have serrated
borders, especially in fishes.

The retina, or nervous portion of the eye, is the most
important, as its delicacy and liability to decomposition
render it the most difficult object of microscopic exami-
nation.

"We must dismiss the popular notion of minute images

THE MICROSCOPE IN ANIMAL HISTOLOGY. 221

produced on the retina by the lens to be viewed by the
mind. The lens does, indeed, form an image on the mem-
brane, so it would on glass or paper, but the real action
of the vibrations of light upon the nervous conductors is
not thus to be explained.

The complex structure of the retina is only recently
known, and it may be that many laws of light yet un-
known are to be exhibited by its means, as well as much
that relates to the connection of the perceiving thinking
mind and the external world.

Muller's fluid, concentrated solution of oxalic acid, 0.6
per cent, solution of sulphuric acid, and 0.1 to 2 per cent,
solutions of osmic acid, may be used for hardening, but
very delicate dissection is required for demonstration.
Rutherford recommends chromic acid and spirit solution,
1 gramme of chromic acid in 20 c.c. of water, and 180 c.c.
of methylated spirit added slowly.

The retina consists of the following layers : 1. The
columnar layer, or layer of rods and cones. 2. Membrana
limitans externa. 3. External granular layer. 4. Inter-
granular layer. 5. Internal granular layer. 6. Molecular
layer. 7. Ganglionic cell layer. 8. Expansion of optic
nerve. 9. Membrana limitans interna. To these may be
added : 10. The pigment layer, often described as the
pigmented epithelium of the choroid, into which the rods
and cones project. These layers are composed of two
different elements, mutually blended, a connective-tissue
framework of varying structure in the different layers,
and a complex nervous tissue of fibres, ganglia, rods, and
cones. Plate XXIV, Fig. 177, is a diagram of these
separate structures, after M. Shultze, in Strieker's Man-
ual of Histology.

The structure of the rods and cones is complex, and
varies in different animals. The rods readily decompose,
becoming bent and separated into disks, but examination
of well-preserved specimens shows them to have a fibril-

222 THE MICROSCOPIST.

lated outer covering. In addition, certain globular or
lenticular refractive bodies, of different shape and color
in different animals, are found in these structures (Plate
XXI Y, Fig. 178), which doubtless are designed to give
the rays of light such a direction for final elaboration in
the outer segment as they could not receive from the
coarser refractive apparatus in the front of the eye.

e. Organs of Hearing. — These are most intimately con-
nected with mental functions, because of language, which
is the highest sensual expression of mind. Hence the
structure of these organs is most delicate and complex.

The labyrinth is the essential part of the organ, con-
sisting in man of the vestibule, the semicircular canals,
and the cochlea. Sonorous undulations are propagated
to the fluid in the labyrinth through the tympanum and
chain of otic bones.

The auditory nerves are distributed to the ampullae and
sacculi of the vestibule, and to the spiral plate of the
cochlea. At the terminal filaments in the sac of the
vestibule, crystals, called otoliths, of shapes differing in
various animals, are inclosed in membrane. Hasse con-
siders them to be vibrating organs, but Waldeyer regards
their function to be that of dampening sound.

As we distinguish in sounds the various qualities of
pitch, intensity, quality, and direction, it is probable that
there is a special apparatus for each, but histology has
not yet established this fully. Kolliker thinks the gan-
glionic termination of the cochlear nerve renders it proba-
ble that it only receives sonorous undulations. The ex-
periments of Flourens seem to show that the semicircular
canals influence the impression of direction of sound.

In the sacs of the vestibule and ampullae, the nerve-
fibres are confined to a projection of the walls called the
septum nerveum. Here are found cylinder- and fibre-cells,
with rods, basal-cells, and nerves. But it is in the lamina
spiralis.of the cochlea that the. most elaborate organ,

PLATE XXIV.

FIG. 175.

FIG. 176.

Olfactory cells.

Section of Cornea.

FIG. 177.

FIG. 179.

Connective-tissue and nerve-elements of Retina.
Showing rods and cones.

Section of Cochlea:— v, seal a vestibuli; T, scala
tympani; c, canal of Cochlea; R, Reissner's mem-
brane, attached at a to the habenula sulcata; 6,
connective-tissue layer ; c, organ of Corti.

FIG. 178.

FIG. 180.

Refractive bodies in the rods and cones.

FIG. 181.

Corti's organ, from above.

Section of Corti's organ.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 223

called from its discoverer the organ of Corti, is found.
Kolliker considers the free position of the expanded por-
tion of the nerve, and the extent of surface over which
its terminal fibres are spread, to constitute it an organ of
great delicacy, enabling us to distinguish several sounds
at once and to determine their pitch. There is a striking
analogy between the visual and auditory apparatus in the
ganglionic structure of the nerve-structure. Plate XXIV,
Fig. 179, represents a vertical section through the tube
of the cochlea; and Plate XXIY, Figs. 180 and 181, the
vestibular aspect and a vertical section of Corti's organ.

Waldeyer recommends examination of the cochlea in a
fresh state and in aqueous humor. Preparations in osmic
acid and chloride of gold are also useful. For sections he
removes much of the bony substance of large cochleae with
cutting pliers, opens the membrane in several places, and
places the specimen in 0.001 per cent, of chloride of palla-
dium, or 0.2 to 1 per cent, osmic acid solution for twenty-
four hours, then for the same time in absolute alcohol.
It is then treated with a fluid composed of 0.001 per cent,
chloride of palladium with one-tenth part of J to 1 per
cent, muriatic or chromic acid, to deprive it of earthy
salts. It is then washed in absolute alcohol, and inclosed
in a piece' of marrow or liver, and placed to harden in
alcohol again. The hollows of the cochlea may be filled
with equal parts of gelatin and glycerin before they are
inclosed. Sections must be cut with a sharp knife.

Rutherford advises the softening of the bone and hard-
ening of other tissues by maceration in chromic acid and
spirit (1 gramme of chromic acid in 20 c.c. of water, and
180 c.c. of methylated spirit slowly added). For sections
he commends Strieker's mode of imbedding in gum. Place
the cochlea in a small cone of bibulous paper, containing
a strong solution of gum arabic, for four or five hours ;
then immerse the cone in methylated spirit for forty-eight

224 THE MICROSCOPIST.

hours, or until the gum is hard enough. The sections
may be stained with carmine, logwood, silver, or gold.

The following suggestions from Rutherford's Outlines
of Practical Histology, will be of service to the student in
this department :

Most of the tissues required may be obtained from the
cat or guinea-pig. Feed the cat, and an hour or so after
place it in a bag; drop chloroform over its nose until it is
insensible. Open the chest by a linear incision through
the sternum, and allow the animal to bleed to death from
a cut in the right ventricle.

Divide the trachea below the cricoid cartilage and in-
ject it with | per cent, chromic acid fluid ; tie it to prevent
the escape of fluid, and place the distended lungs in the
same fluid, and cover them with cotton-wool. Change
the fluid at the end of eighteen hours. Allow them to
remain in this fluid for a month, then transfer to methy-
lated spirit till needed for mounting.

Open by a linear incision the oesophagus, stomach, large
and small intestines, and wash them with salt solution (£•
per cent.). Place a portion of small intestine in chromic
and bichromate fluid (1 gramme chromic acid and 2
grammes potassium bichromate in 1200 c.c. water) for two
weeks (change the fluid at the end of eighteen hours), and
then in methylated spirit till required. Act similarly
with parts of oesophagus, stomach and large intestine, in
J per cent, chromic acid for three or four weeks. A por-
tion of stomach may be placed in Muller's fluid till re-
quired for preparation of non-striped muscle, and of the
gastric follicles.

The bladder may be treated as the small intestine.
• Divide one kidney longitudinally, and the other trans-
versely, and place in Muller's fluid. Change the fluid in
eighteen hours, and after four weeks transfer to methy-
lated spirits. They will be ready for use in two weeks
after.

THE MICROSCOPE IN ANIMAL HISTOLOGY. 225

'Cut one-half of the liver into small pieces and prepare
as the kidneys. The tongue, divided transversely into five
or six pieces, the spleen, uterus, and thin muscles from
limbs or abdomen, in J per cent, chromic acid. Change as
before, and in a month to methylated spirit.

Testis of dog, freely incised, and ovaries of cat or dog,
in Muller's fluid, and after three weeks to methylated
spirits.

Divide the eyes transversely behind the lens. Remove
the vitreous. Place posterior halves in chromic and spirit
solution. Change in eighteen hours. Transfer to methy-
lated spirit in ten days. Place the lens in Muller's fluid
for five weeks, and then in methylated spirits. The cor-
nea may remain in J per cent, chromic acid for a month,
and then in methylated spirit.

Cautiously open the cranial and spinal cavities. Re-
move brain and cord, and strip oft' arachnoid. Partially
divide the cord into pieces a half inch long. Partially
divide the brain transversely into a number of pieces.
Place in a cool place in methylated spirits for eighteen
hours. Transfer cord to \ per cent, chromic acid for six
or seven weeks. Change in eighteen hours. Prepare the
sciatic nerve in the same manner. Place the brain in
chromic and bichromate fluid. Change in eighteen hours,
and then once a week, until the brain is hard. If not
leathery in six weeks place in J per cent, chromic acid for
two weeks, and then in methylated spirits. Support the
brain and cord on cotton-wool in the hardening fluid.

Remove muscles, but not periosteum from bones of
limbs, and both from the lower jaw. Divide the bones
transversely in two or three places, and put them in chro-
mic and nitric fluid (chromic acid, 1 gram ; water, 200
cc. ; then add 2 cc. nitric acid). Change the fluid often
until the bone is soft enough, and transfer to methylated
spirits. If not complete in a month, double the quantity
of nitric acid in the fluid.

15

226 THE MICROSCOPIST.

Place a piece of human scalp, skin from palmar surface
of finger, and skin of dog (for muscles of hair-follicles) in
chromic and spirit fluid. In a month transfer to methy-
lated spirit.

Remove the petrous portion of temporal bone, open the
tympanum, pull the stapes from the oval fenestra, and
place the cochlea in chromic and spirit fluid. Change in
eighteen hours, and at the end of seven days, if a brown
precipitate falls, change fluid every third day. On the
tenth or twelfth day transfer to chromic and nitric fluid.
Change frequently till the bone is soft. Then place it in
methylated spirit. The cochlea of the guinea pig pro-
jects into the tympanum, and is, therefore, convenient for
enabling the student to see how the cone is to be sliced
when sections are made.

Too long exposure to chromic acid renders tissues fria-
ble, and prevents staining with carmine.

Methylated spirit is ordinary alcohol containing 10 per
cent, of wood-naphtha, and is used in England as a sub-
stitute for alcohol, since it is free of duty for manufactur-
ing purposes.

CHAPTER XIII.

THE MICROSCOPE IN PATHOLOGY.

PATHOLOGICAL histology treats of the minute anatomy
of the tissues and organs in disease, and is essential to a
knowledge of structural changes in the body. Since the
old method of judging solely by symptoms has given place
to the more rational observation of the actual changes
produced, the microscope has become an indispensable aid
to practical medicine. As anatomy would be coarse and
imperfect without histology, so pathological histology

THE MICROSCOPE IN PATHOLOGY. 227

perfects pathology, and guides to right conclusions the
seeker after positive truth in medicine.

Our plan forbids an extensive outline of the facts of
morbid anatomy. We propose merely such a classifica-
tion of the microscopic appearances of diseased structures
as may serve to guide the student and busy practitioner
in actual observation.

PREPARATION OF SPECIMENS.

Much may be learned by the examination of a patho-
logical specimen without any preparation whatever, or
with the use of indifferent fluids (see Chapter V). A thin
section may be made under water with a Valentin's knife,
or a small portion may be snipped off with curved scis-
sors and teased with fine needles. The freshly-cut sur-
face of tumors may be gently scraped with a knife and
the separated elements examined in glycerin and water.

For a thorough examination it will be necessary to
harden, stain, and make thin sections, as described in
Chapter V and at page 224. Mtiller's fluid, page 68, will
be found most generally useful for morbid specimens.
After small pieces have lain some time in this they can be
still further hardened by absolute alcohol. Before cut-
ting thin sections, either by hand or with a section-cutter,
the specimen will require to be imbedded so as to be
readily held and cut without tearing. A mixture of wax
or paraffin and olive oil is generally used of such consist-
ence as will indent readily with the thumb-nail when
cold. For very delicate tissues, saturation in a mixture
of glycerin and gum arabic, made perfectly clear and vis-
cid, so as to be easily drawn out into threads, is useful.
After saturation the specimen is thrown into alcohol,
which hardens the gum and fixes the tissues so as to be
readily cut. The thin section can be thrown into water,
or carmine solution, to dissolve the gum, and the stained

228 THE MICROSCOPIST.

preparation can be mounted in glycerin, balsam, or dam-
mar (Chapter YI). In fixing the cover to specimens
mounted in glycerin it may be useful to apply liquid glue
or strong gelatin solution to the edges, using the turn-
table or otherwise, and after it is dry to cover it with
some other cement. Any glycerin which may accident-
ally be on the cover had better be left until the glue has
dried, when it can be removed by a camel's hairbrush and
water.

Dr. Beale recommends that nitrate of silver, chloride
of gold, osmic acid, etc., when used for staining fine tis-
sues, should be dissolved in glycerin. Less than J per
cent, solution of gold, etc , will thus bring out details
which are scarcely attained otherwise. The time of soak-
ing and strength of the solution varies according to the
tissue and effect desired.

The most delicate sections are made by freezing speci-
mens after they have been well saturated with a strong
solution of gum arabic. For this purpose Professor
Rutherford's freezing microtome has been invented, in
which the cylinder of the ordinary section-cutter, page
63, is surrounded by a reservoir for powdered ice and salt,
so as to freeze the tissue. Dr. Beale recommends freez-
ing by the use of nitrous oxide gas, and Dr. Pritchard
has suggested a metallic cylinder with a wooden handle,
which can be cooled below the freezing-point by salt and
ice. A small piece of tissue will immediately freeze on
the metal so as to be cut into thin sections by hand. If
thawing sets in it may be covered with thin gutta-percha
and plunged into the ice and salt.

Dr. S. Marsh, in an excellent little treatise on section-
cutting, recommends that the knife should not be ground
flat on one side, but be slightly concave on each side. In
cutting it is necessary to keep the blade well flooded with
spirit, except in using the freezing microtome. The sec-
tions are best transferred to a basin of water, and lifted

THE MICROSCOPE IN PATHOLOGY. 229

to the staining fluid, etc., not with a camel's hair brush,
but with a little slip of tin, copper, etc., with a bent and
perforated end, making a sort of lifter or flat spoon. In
making sections, either by hand or with the section-cut-
ter, the razor or knife must be kept always sharp, and
drawn from heel to point so as to cut with a single stroke
the thinnest possible slice.

THE APPEARANCE OF TISSUES AFTER DEATH.

Formation and decomposition, or progression and retro-
gression, coexist in most morbid structures, so that it is
necessary for the student not only to be familiar with
normal histology, but also with the products of decay and
death and the varied appearances in disease.

The death of the individual parts of the organism is
called necrosis, mortification, or gangrene. Various changes
follow it, depending chiefly on moisture, producing dry or
moist gangrene.

Necrosis depends on the cessation of the nutritive pro
cess from abolition of the normal supply of blood, or from
mechanical or chemical violence.

Living tissues bathed in suitable fluids dissolve albumi-
nates and their derivatives, but when life departs they no
longer withstand solution themselves.

1. Protoplasm. — It has been shown, page 118, that the
term bioplasm has been appropriated to elementary or
germinal structure during life, and at page 188 we re-
garded the leucocytes, or white corpuscles of the blood,
chyle, etc., as simply bioplasts. After death, or in order
to designate their physical constitution, the most suitable
term for them is protoplasm. In necrosis this colorless
protoplasm dissolves after slightly swelling, and entirely
disappears.

2. Blood. — Decomposes very rapidly. The coloring
matter leaves the red corpuscles and is diffused through

230

THE MICROSCOPIST.

FIG. 182.

the tissues (hence the dark color of a scab), then the cor-
puscle disintegrates and breaks up into granules. Some-
times there is found an aggregation of brownish-colored
blood-corpuscles undergoing disintegration at the edges as
in Fig. ] 82.

3. Nucleated Cells.— In these the
protoplasm coagulates, forming a
solid albuminate, which becomes
cloudy and breaks up into gran-
ules.

4. Cell membrane resists de-
composition in proportion as it
has become horny. Hence the
outer layers of epithelium last
longer than the inner ones.

The gangrenous disintegration of 5" Smooth MuSOldar Fibre.—

tissues, a. Aggregation of biood-cor- Minute dusty granulations first

puscles. 6. Smooth muscular fibres. , .

c. striated muwuiar fibres. & Break- make their appearance, which

ing up of same into Bowman's disks. unite go t^at t]ie f^re Seems
1-300.— After EINDFLEISCH.

transversely striated. As decay

goes on the muscle changes into a slimy granular substance
which may be drawn into threads.

6. Striated Muscular Fibre. — The muscle-juice coagu-
lates to a solid albuminate, giving rise to rigor mortis in
from twelve to fourteen hours after death, except in death
from charcoal or sulphuretted hydrogen vapor, lightning,
or from putrid fevers, or long debility. This stiffness of
muscle lasts about twenty-four hours. In the necrosed
fibres under the microscope the transverse striae and nu-
clei disappear amid a cloud of minute granulations, then
fat-globules and reddish pigment-granules show them-
selves, the fibres melt away from the edges and become
gelatinous. If gelatinous softening is marked the fibres
may disintegrate into Bowman's disks, or disks produced
by transverse cleavage (Fig. 182).

7. Nerve-tissue. — Little is known of the process of de-

THE MICROSCOPE IN PATHOLOGY.

231

FIG. 183.

cay in nerves save that the thicker nerve-trunks maintain
themselves for a comparatively long time, while the finer
ramifications soon dissolve. The white substance of
Schwann (page 199) first coagulates, then there is a col-
lection of drops of myelin within the neurilemma, produc-
ing varicosity before complete dissolution.

8. Adipose Tissue. — The fluid fat leaves the cells and
gives an appearance of emulsion to the mass. Crystals of
margarin, etc., sometimes appear on the cell-walls.

9. Loose connective tissue fibres swell, become stained
with the coloring matter of blood, granulate, and liquefy ;
or they may desiccate by evaporation.

10. Elastic fibres and fi-
brous networks resist longer
than the last. Hence, elastic
fibres may be found in expec-
torated matter from gangre-
nous lungs, etc. Later they
break into granular strise, then
into molecules and vanish.

11. Cartilage lasts long, but
melts away at the edges, first
becoming transparent and red-
dish. The cells fill with fat-
globules from fatty degenera-
tion of the bioplasm.

12. Bone retains its struc-
ture long, so as to be recog-
nized by the surgeon in seques-
trse, yet it decays in patches.
The bioplasm changes to fat
in the cells, acid fluids dissolve

the lime salts, and the remaining structure disintegrates
like cartilage.

The chemical products of decomposition are but par-
tially known. Some are volatile, some soluble in water,

Products of gangrenous disintegra-
tion, a. Leucin ; 6. Tyrosin; c. Fat-
crystals ; d. Ammoniaco-magnesian
phosphate ; e. Gangrene particles (blacfe
pigment);/. Vibriones. 1-300,— After

KlNDFLEISCH.

232 THE MICROSCOPIST.

and others more solid, producing a new series of micro-
scopic objects after the disappearance of the histological
forms (Fig. 183).

Leucin (Fig. 183, a) forms partly homogeneous drops
or globules, partly bodies of concentric layers, and partly
stellate spheres of minute crystalline needles.

Tyrosin (b) generally found along with leucin, forms
satiny white needles, isolated, or in sheafs or rosettes.

Margarin (c) a mixture and crystalline separation of
the solid fats, stearin, and palmitin, occurs quite fre-
quently.

Ammoniaco-magnesian phosphate (d) is only found in
alkaline or neutral ichor.

Pigment-bodies (e) are very small, and have a variety of
forms. As characteristic of necrosis the small, black,
irregular particles, resisting most reagents, must be dis-
tinguished from hsematin pigments, though they are
probably identical with melalin.

Living Organisms (/). — In addition to minute fungi, or
moulds (aspergillus, oidium, etc.), vibriones are quite com-
mon. Pasteur regards them as the visible elements of
decay (see page 135).

DEGENERATION OF TISSUES.

Degenerations are usually divided into two classes, true
degenerations, or metamorphoses, and the infiltrations.

1. The true degenerations or metamorphoses are char-
acterized by the direct change of the albuminoid constitu-
ents of the tissues into new material. The metamor-
phoses include fatty, mucoid, and colloid degenerations.

2. The infiltrations differ from the true degenerations,
since the new material which exists in the tissues is not
derived from their albuminoid constituents, but is de-
posited in them from the blood. The anatomical char-
acters are much less altered than in the metamorphoses,

THE MICROSCOPE IN PATHOLOGY.

233

FIG. 184.

and function is usually less interfered with. They include
fatty, amyloid, calcareous, and pigmentary infiltration, etc.

THE METAMORPHOSES.

1. Fatty Degeneration.

The metamorphosis of the protoplasm of the cell is
marked by the occurrence of fat-
globules in its interior. Its pro-
gress may be illustrated by de-
generating epitheliun in dropsy
of the pericardium (Fig. 184).

The granular corpuscles were
formerly known as the " inflam-
matory " or u exudation corpus-
cles," or " corpuscles of Gluge."
They are identical in structure
with colostrum-corpuscles thrown
off by the mammary gland after
parturition, and the last act of
fatty degeneration is considered

as a lactification. The fatty detritus may be absorbed as
milk, or if not absorbed it is partly saponified and partly
separated in solid form, as margarin, etc. Finally there is
an abundant deposition of crystals of cholesterin (Fig. 185).

This substance is found nor-
mally in the brain and spinal
marrow in quite large propor-
tions, and in solution in the
bile. It forms rhombic tablets,
lying in heaps, with their long
sides parallel.

In some cases when the fatty
detritus is not absorbed it
undergoes a change into a
crumbling material somewhat
resembling cheese, and hence called 'caseation. This ap-

The fatty metamorphosis. Epi-
thelium of the pericardium in
dropsy of pericardium, a. Cells
which still show the normal form
and arrangement. First appear-
ance of fat-globules, b. Granular
globules, the one with a nucleus
still visible, c. Granular globules
disintegrating to fatty detritus. —
After KINDFLEISCH.

FIG. 185.

Crystals of cholesterin.— After VIR-
cuow.

234

THE MICROSCOPIST.

pears to be owing to desiccation of the substance from de-
ficient vascular supply. It is most frequent in parts which
contain but few vessels, or in those in which the vessels
are obliterated by new growths. It was formerly believed
to be the product of tuberculosis, and regarded as the
separation of morbid matter (crude tubercle) from dis-
eased blood. Tubercle may undergo fatty degeneration
and caseation, but it is by no means true that all cheesy
masses are tubercular.

Fatty degeneration in the arteries may be illustrated
by atheroma, beginning as a fatty metamorphosis of con-
nective tissue, and ending in calcification or impregnation
with lime salts. In the fibres of voluntary muscle the al-
buminous matter of the fibre is converted into fat, which
is seen in rows of minute globules, like strings of pearls
in the long axis of the primitive bundles, while the trans-
verse striae become indistinct (Fig. 186).

In advanced stages of infantile spinal
paralysis, perhaps from inaction as well
as innutrition, the atrophied muscles are
subject to fatty degeneration, which may
be observed by removing small portions
of muscular tissue by Duchenne's trocar,
a sort of double needle, one part of which
slides upon the other, jutting against a
steel shoulder, so as to catch and detach
a small piece from a muscle into which it
is inserted. A microscopic examination
of the detached fibre will show the
amount of degeneration, and thus from
time to time the progress of disease or
the effects of treatment may be noted.

In pulmonary emphysema the epithe-
lium is so changed by fatty degeneration
that the degenerated elements are better

FIG. 186.

Fatty degeneration
of striated muscular
fibres. 1-300.— After

RlNDFLEISCH.

seen than the normal (Fig. 187).

TUB MICROSCOPE IN PATHOLOGY.

235

Softening of the brain, as it is termed, is largely due to
fatty degeneration. Whatever interferes with nutrition,
by preventing a proper supply of blood, will produce fatty
degeneration and softening. Acute cases may be pro-
duced by embolism or thrombosis. White softening is
generally a chronic condition of old age, and owes its

FIG. 187.

From the inner surface of a larger emphysema vesicle. Fatty remains of the lung-
tissue, containing elastic fibres, smooth muscular fibres, and covered with fatty degen-
erated epithelia. 1-500. — After RINDFLEISCH.

color to the gradual diminution of blood-supply. Yellow
and red softening depend on larger proportions of blood-
pigments. A vertical section of a specimen of yellow
softening shows accumulations of fatty granules between
the nerve-fibres, and their formation into larger granular
corpuscles (Fig. 188).

2. Mucoid Degeneration.

This is a transformation of albuminoid tissues into
mucin, a material of a soft jellylike consistence. This is

236

THE MICROSCOPIST.

the embryonic condition of most tissues, and in the um-
bilicus and the vitreous humor of the eye this character
persists after birth.

The mucus which normally covers the mucous mem-
branes is largely, if not wholly, derived from the swell-
ing and softening of epithelial cells, but in mucoid degen-

FIG. 188.

Yellow softening of the white substance of the brain. A. Border of the depot of soft-
ening, S, and of the brain-substance, C, not yet softened. D. A fatty degenerated ves-
sel. 1-300.— After RINDFLEISCH.

eration the change chiefly pertains to the intercellular
elements. Thus cartilage softens (Fig. 189).

The matrix first exhibits strise which afterwards split
into fibres. The ends of the fibrils taper to a point and
are dissolved by mucoid metamorphosis. In bone the
solution of the lime salts and the liquefaction of the basis-
substance are generally simultaneous, but in some cases,
as in Fig. 190, the difference between? the two is quite
apparent.

3. Colloid Degeneration.

In this the cells, rather than the intercellular structure,
are especially involved. Colloid resembles mucin in ap-

THE MICROSCOPE IN PATHOLOGY. 237

pearance, but unlike it contains sulphur and is precipi-

FIG. 189.

Softening of cartilage. Vertical section of an articular cartilage in malum senile ar-
ticulorum. 1-300.— After RINDFLEISCH.

FIG. 190.

Softening of bone. Fragment of bone from the spongy substance of an osteomala-
cious rib. a. Normal osseous tissue ; 6. Decalcified osseous tissue ; c. Haversian canals ;
d. Medullary spaces; d*. A medullary space filled with red medulla. 1-300.— After
RINDFLEISCH.

238

THE MICROSCOPIST.

tated by acetic

FIG. 191.

Colloid degenerat-
ing cells from a colloid
cancer — After RIND-

FLEISCH.

acid. It resembles jelly or half-set glue.
It first appears as a small globule in the
cell, which grows, pushing aside the nu-
cleus, until it not only fills the cell but
swells largely , communicating with neigh-
boring cells so as to form cystlike cavi-
ties containing the gelatinous substance.
Here it may afterwards undergo lique-
faction (Fig. 191).

The colloid change is most common in
enlargements of the thyroid gland, in the
lymphatic glands, and in many of the
new formations. Colloid or mucoid tu-
mors, or tumors which have undergone
these forms of transformation, are some-

FIG. 192.

Colloid degeneration in the stronia of an ovarian cystoid. a, a. Larger cysts, whose
walls bear an incomplete epithelium of low cylindrical cells whose contents after hard-
ening is split up radiating. 6. Younger cysts without epithelium permeated by remains
of connective tissue fibres, c. The same with a wreath of loose epithelia d. Colloid
infiltration of the connective tissue which has not yet attained any cystoid appearance
and inclosure. «. Small-celled infiltration of the stroma. 1-200.— After EINDFLEISCH.

THE MICROSCOPE IN PATHOLOGY. 239

times called colloid cancers, when their structure may be
altogether different from cancer.

Some forms of multilocular ovarian cysts depend, ac-
cording to Rindfleisch, upon a colloid degeneration of the
stroma of the ovary, wherein an epithelial proliferation
furnishes the foundations of the cysts. Such a case may
be termed a cystic colloid cancer of the ovary (Fig. 192).

THE INFILTRATIONS.

1. Amyloid Infiltration.

This is known also as lardaceous or waxy degeneration
and vitreous swelling. It consists of the infiltration of
some sort of albuminate from the blood, which is charac-
terized by its becoming brownish-red or violet color by
treatment with iodine. It sometimes exhibits concentric
layers, like starch, which with the color phenomena led
Virchow to call it amyloid.

The amyloid infiltrated cell (Fig. 193) is distinguished
from the normal by its greater circumference, together

FIG 193

Amyloid infiltrated liver-cells, a. Isolated cells, b. A fragment of the liver-cell net-
work, in which the dividing lines of the individual cells are no longer visible. 1-300.
—After RINDFLEISCH.

with a certain rounded irregularity. If several are in
contact they often coalesce into elongated lumps, in which
the individual elements connot be recognized.

The walls of small arteries and capillaries are the first
to be attacked in all infiltrations, and this is especially
observable in amyloid infiltration. Fig. 194 represents
partial amyloid infiltration of a Malpighian tuft of the
kidney. The blue injection, and of course the blood dur-

240

THE MICROSCOPIST.

ing life, penetrates only the capillary loops which are free
from deposit. The addition of iodine, staining the amy-
loid matter red, gives an alternation of blue and red loops.

FIG. 194.

Amyloid infiltrated Malpighian vascular coil of the kidney. 1-300.— After RINDFLEISCH.

Amyloid infiltration impairs the nutrition of a part
both by the obstruction of the circulation and by its
direct influence. Hence atrophy and fatty metamorphosis
are often found associated with it.

In lardaceous liver, or amyloid infiltration of the liver,
the minute branches of the hepatic artery are first affected,
then the region of the hepatic vein, and afterwards the

FIG. 195.

Amyloid liver. A. Interlobular artery with amyloid walls. G, G. Biliary ducts.
p,p. Portal vessels. V, V. Interlobular veins. The liver-cells in the central zones of
the acini are infiltrated with amyloid substance. 1-300.— After BINDFLEISCH.

THE MICROSCOPE IN PATHOLOGY.

241

hepatic cells in the region of the portal vein, until the
whole organ may ultimately have twice as much solid
albuminous substance as normal, and becomes pale gray
in color, translucent, and of vvaxlike consistence (Fig. 195).

2. Calcification.

Calcification is the infiltration of tissue with solid phos-
phate or carbonate of lirne. Free carbonic acid is solvent
of these salts, and by its capacity for diffusion it escapes,
leaving the insoluble salts in the nutritive fluid.

Thus cartilage normally becomes bone, and under pecu-
liar circumstances other tissues ossify. True osseous tis-
sue, however, differs greatly from mere calcification by

FIG. I9fi.

Arthritis uratica. Vertical section through a superficial articular body infiltrated with
urate of lime. a. The surface. 6. Cartilage cavities with tufts of crystals, c. Cartilage
cells not yet infiltrated, in division, d. Isolated needles of crystals in the basis-substance.
— After CORNEIL ET EANVIER.

the arrangement of its solid particles (see page 195).
Calcification of arteries is a secondary affection, succeed-
ing to fatty degeneration of the connective tissue.

Analogous to calcification is the arthritic deposit of

16

242

THE MICROSCOPIST.

FIG. 197.

urates into articular cavities, and the parenchyma of the
cartilage, bones, and membranes of the joints of gouty
persons. It is most common in the cartilage cells (Fig.
196).

The uric acid infiltration acts as a mechanico-chemical
agent to the affected parts, producing oedema, suppura-
tion, caries, etc.

3. Pigmentation.

All true pigments are derived from the coloring matter
of the blood. Many of them are elimi-
nated by the kidneys and liver, but some
are deposited in the tissues, as the choroid
coat of the eye and the rete Malpighii of
the skin. Some pathological cases may
be ascribed to extravasation or some local
stasis in the circulation ; others may be
caused by wandering leucocytes (page
188). The brown atrophy of the muscu-
lar tissue of the heart, which is often as-
sociated with marasmus, is caused by the
deposit of yellow granular pigment in the
muscular fibre (Fig. 197).

The dark pigment of the lungs owes
its origin chiefly to the respiration of
carbon in the shape of particles of soot,
coal-dust, etc., floating in the atmosphere. These parti-
cles are first taken up by the mucous corpuscles (leuco-
cytes) of the trachea and bronchi, and many of them are
expectorated. Some, however, make their way to the
air-vesicles, and penetrate the alveolar walls and inter-
lobular tissue (Fig. 198).

In the case of coal-miners the lungs often become uni-
formly black. Workers in iron-dust are liable to have
the lungs stained red from oxide of iron, and stonecutters,
etc., to inhale and deposit silicic acid or fine sand. Such

Brown atrophy of
heart-muscle. Frag-
ment of a membrane
of muscular fibres,
with pigment-gran-
ules in the interior
of the primitive bun-
dles. 1-300. — After

RlNDFLEISCH.

THE MICROSCOPE IN PATHOLOGY.

243

particles produce irritation and inflammatory phenomena,
accompanying which is a formation of true pigment from
the blood, whose deposit increases the darkness of tint in

FIG. 198.

FIG. 199.

Anthracosis. Coal-dust inhaled into the alveolar septa of the lung. 1-3)0.— After

ElNDFLEISCH.

the lungs. Many morbid conditions, also, are attended
with formation of pigment.

4. Fatty Infiltration.

In this form of degeneration the fat is derived from the
food, and must be distinguished from
that metamorphosis called fatty degen-
eration. In fatty infiltration the fat
occurs in the cells as distinct drops of
oil (Fig. 199).

The vitality and functions of the cells
are but little impaired by the^ accumu-
lation, which may be again reabsorbed,
while in fatty metamorphosis the ele-
ments are destroyed. Fatty infiltra-
tion of muscle is seen in the connective
tissue between the fasciculi, and not in
the muscular fibres themselves as in fatty degeneration.

Fatty infiltrated liver-
cells. 1-300. — After

RlNDFLEISCH.

244

THE MICROSCOPIST.

The " fatty liver," as it is called, is due to infiltration.
The ingestion of fatty aliments is followed by temporary
accumulation of fat in the portal blood, which is apt to be
deposited in the portal capillaries of the liver, which is
gradually conveyed to the central or hepatic capillaries of
the lobules, and thus to the general circulation. In mor-
bid conditions, as in tuberculosis and heart disease, we
find the morbidly fatty liver first infiltrated in the portal
zone as in Fig. 200.

FIG. 200.

Fatty liver of moderate degree, serai-diagrammatic. V. Lumina of the central veins.
p. Interlobular branches of the vena portae. A. Arterial branches. G. Biliary ducts. —
After RINDFLEISCH.

In more advanced cases all the liver-cells become filled
and the bounds of the acini are effaced. Fat may occur
in the liver in connection with general obesity, or from a
failure of the oxygenating power of the blood, in which
case there may be general emaciation.

5. Albuminous Infiltration.

Albuminous infiltration, or cloudy swelling, consists in
filling the tissues with molecular albumen. It is regarded
by Virchow as a nutritive irritation, or an in citation of

THE MICROSCOPE IN PATHOLOGY.

245

cells to take up an abnormal amount of nutritive mate-
rial. It occurs after local and general irritations, which
bring to the part an increased supply of blood, and is es-
pecially important in the muscles and the large glands, as
the liver and kidneys. In the latter it is often associated
with fatty degeneration and fibrinous exudation, as in
Fig. 201.

FIG. 201.

1. Cloudy swelling and commencing fatty degeneration of the epithelia of the convo-
luted urinary tubuli. 2. Advanced fatty degeneration. 3. Formation of fibrinous cyl-
inders, a. Cross-cut of a urinary tubulus, with a gelatinous cylinder filling the lumen.
b. Epithelium, c. Tunica propria. d. Renewed production of colloid at the surface of
the epithelial cells, which elevates the older. 1-500.— After RINDFLEISCH.

6. Serous Infiltration.

This is an infiltration of the tissues with a serous or
sero-mucous substance producing oedema, and seems
analogous to mucoid degeneration. Under the micro-
scope bright spots appear in various cells, of which Wag-
ner declares it to be uncertain whether they are artificial
or diseased products, and if the latter, whether they are
serous, mucous, or colloid.

246 THE MICROSCOPIST.

INFLAMMATION.

Inflammation is a complex process, beginning with an
increased flow of blood into or towards the part affected,
and generally leading to exudation or suppuration, some-
times healing by resolution or leading to new formations,
to various metamorphoses, or to destruction of tissues,
with a disturbance of the function of the part affected.

Inflammation of the various tissues or organs are dis-
tinguished by adding the termination itis to the Latin or
Greek term, as encephalitis, pleuritis, nephritis, etc. ; or a
special name is given, as pneumonia, for inflammation of
the lungs, erysipelas, for inflammation of the skin, etc.

Inflammations of serous coverings of organs receive the
prefix peri, as perihepatitis, perimetritis, etc. (except peri-
bronchitis, and peri phlebitis, which refer to inflammation
of the exterior of the bronchial or venous wall). Inflam-
mations of the surrounding connective tissue or appen-
dages of an organ are known by the prefix para, as para-
nephritis, paraeystitis, parametritis, etc.

Inflammation is the result of some kind of injury to
the tissue affected, either direct, as from mechanical or
chemical agents, or indirect, as from specific contagions,
exposure to cold, etc.

The first phenomenon of inflammation is congestive
hypersemia, or an increased flow of blood. There is first
a dilatation of the vessels, with an acceleration of the
current, which is soon followed by a retardation of the
current, producing stagnation or cessation of circulation.
Several theories have been advanced to explain this phe-
nomenon. According to the paralytic theory the irrita-
tion affects only the sensitive nerves, e. g., of the skin,
and produces an antagonistic paralysis in the vasomotor
nerves. The vessels then relax, dilate, and receive more
blood. According to Virchow and Beale, it is the cell in

THE MICROSCOPE IN PATHOLOGY.

247

itself without the intervention of the nerves or the blood,
which is excited to increased nutritive activity, to greater
metamorphosis, and to new formation ; and the more
quickly this takes place, the more it runs the danger of de-
struction, the more is the process to be looked on as in-
flammatory. There may be truth in both these views,
since the nutrition of the cell is so greatly influenced by
nerve action.

The second phenomenon of inflammation is exudation
and suppuration. The most disputed point respecting in-
flammation has been the genesis of pus-corpuscles. We
have seen, page 189, that they are identical in the living
state wuh leucocytes, or white blood-cells. In other words,
they are merely particles of bioplasm. Their migration

FIG. 202.

Cohnheim's experiment, a. Vein, b b. Contiguous connective tissue, permeated by
migrating colorless blood-corpuscles, c. Column of red blood-corpuscles. 1-500.— After

RlNDFLEISCH.

through the walls of bloodvessels was first described by
Dr. Addison in 1842, and afterwards, in 1846, by Dr.
Waller. These observations w^ere forgotten, however, un-
til 1867, when Professor Cohnheim, of Berlin, showed the

248 THE MICROSCOPIST.

importance of this migration to the pathology of inflam-
mation. His experiment consisted in stretching the mes-
entery of a living frog, paralyzed by the subcutaneous in-
jection of I per cent, solution of curare, over a ring of cork,
and placing it under the microscope. The veins are seen to
dilate, and the colorless blood-corpuscles first cling to the
inner surface of the wall of the vessel, then a process from
the bioplast passes through the wall, which swells up out-
side, and in this wray a bridge is formed upon which the
whole substance of the cell creeps over. By their amoeboid
motions the cells wander further, and accumulate at the
irritated part of the tissue which becomes the point of de-
parture for future changes (Fig. 202).

Strieker has shown, by experiments on the tongue and
cornea of the frog, that the migratory cells, or pus-cor-
puscles, in inflammation increase by division.

Dr. Beale holds the opinion that although some of the
pus-corpuscles may be derived from the division of colorless
blood-cells, yet the great mass of them results from the
bioplasts of the tissues in which the pus-formation takes
place. In this he follows the earlier teaching of Virchow,
which supplanted the older view that pus-corpuscles origi-
nated in a structureless exudation. Dr. Beale recommends
the examination of a portion of cuticle raised by a small
blister, which may be stained with carmine, or examined
fresh in the serum of the blister. The bioplasm of the
inflamed epithelial cells will be found larger than in the
normal state, and in some instances will be seen to project
beyond the formed material of the cells, and the free
portions divide and subdivide in the exudation poured
out from the bloodvessels.

In Chapter IX we have referred to Dr. Beale's views
respecting the elementary histological unit or cell, which
seem to agree with the phenomena recorded by Max
Schultze, Cohnheim, Strieker,* etc. So influential have

* Strieker's Manual of Histology, chap. i.

THE MICROSCOPE IN PATHOLOGY. 249

been these views in pathology, that we quote from him
the following abstract concerning the changes in the cell
in disease :

" Of the different constituents of the fully formed cell,
the germinal matter is alone concerned in all active
change. This is, in fact, the only portion of the cell
which lives, while at an early period of development the
parts of the cell usually regarded as necessary to cell ex-
istence are altogether absent. The ' cell ' at this period
is but a mass of living germinal matter, and in certain
parts of the body, at all periods of life, are masses of
germinal matter, destitute of any cell-wall, and exactly
resembling those of which at an early period the embryo
is entirely composed. White, blood, and lymph corpus-
cles, chyle corpuscles, many of the corpuscles in the spleen,
thy m us, and thyroid, corpuscles in the solitary glands, in
the villi, some of those upon the surface of mucous mem-
branes, and minute corpuscles in many other localities,
consist of living germinal matter. There is no structure
through which these soft living particles may not make
their way. The destruction of tissue may be very quickly
effected by them, and there is no operation peculiar to
living beings in which germinal or living matter does not
take part. Any sketch of the structure of the cell would
be incomplete without an account of some of the essential
alterations which take place in disease, and it is therefore
proposed to refer very briefly to the general nature of
some of the most important morbid changes.

"If the conditions under which cells ordinarily live be
modified beyond a certain limit, a morbid change may re-
sult. For instance, if cells, which in their normal state
grow slowly, be supplied with an excess of nutrient pabu-
lum, and increase in number very quickly, a morbid state
is produced. Or if, on the other hand, the rate at which
multiplication takes place be reduced in consequence of
an insufficient supply of nourishment, or from other causes,

250 THE MICROSCOPIST.

a diseased state may result. So that, in the great majority
of cases, disease, or the morbid state, essentially differs
from health, or the healthy state, in an increased or re-
duced rate of growth and multiplication of the germinal
matter of a particular tissue or organ. In the process of
inflammation, in the formation of inflammatory products,
as lymph and pus, in the production of tubercle and can-
cer, we see the results of increased multiplication of the
germinal matter of the tissues or of that derived from the
blood. In the shrinking, and hardening, and wasting
which occur in many tissues and organs in disease, we see
the effects of the germinal matter of a texture being sup-
plied with too little nutrient pabulum, in consequence
sometimes of an alteration of the pabulum itself, some-
times of an undue thickening and condensation of the
tissue which forms the permeable septum intervening be-
tween the pabulum and the germinal matter.

" The above observations may be illustrated by reference
to what takes place when pus is formed from an epithelial
cell, in which the nutrition of the germinal matter, and
consequently its rate of growth, is much increased. And
the changes which occur in the liver-cell in cases of cir-
rhosis may be advanced in illustration of a disease which
consists essentially in the occurrence of changes more
slowly than in the normal condition, consequent upon less
than the normal freedom of access of pabulum to the
germinal matter.

" The outer hardened formed material of an epithelial
cell may be torn or ruptured mechanically, as in a scratch
or prick by insects, or it may be rendered soft and more
permeable to nutrient pabulum by the action of certain
fluids which bathe it. In either case it is clear that the
access of pabulum to the germinal matter is facilitated, and
the latter necessarily 'grows' — that is, converts certain
of the constituents of the pabulum that come in contact
with it into matter like itself at an increased rate. The

THE MICROSCOPE IN PATHOLOGY. 251

mass of germinal matter increases in size and soon begins
to divide into smaller portions. Parts seem to move away
from the general mass. These at length become detached,
and thus several separate masses of germinal matter,
which are imbedded in the softened and altered formed
material, result. In this way the so-called inflammatory
product pus results.

"It will be seen how easily the nature of the changes
occurring in cells in inflammation can be explained if the
artificial nomenclature of cell-wall, cell-contents, nucleus
be given up. In all acute internal inflammations a much
larger quantity of inanimate pabulum is taken up by cer-
tain cells and converted into living matter than in the
normal state. Hence there is increase in bulk; cells of
particular organs, wrhich live slowly in health, live very
fast in certain forms of disease. More pabulum reaches
them, and they grow -more rapidly in consequence.

"In cells which have been growing very rapidly and
are returning to their normal condition, in which the access
of nutrient pabulum is more restricted than in the abnormal
state, as is the case in normal cells passing from the em-
bryonic to the fully formed state, the outer part of the
germinal matter undergoes conversion into formed mate-
rial, and this last increases as the supply of pabulum be-
comes reduced.

" We will now inquire what alterations can be observed
in cells, the ''formed material' of which, under normal con-
ditions, becomes quickly resolved into other soluble con-
stituents if these cells be placed under circumstances
which caused the formed material to become harder and
less permeable to nutrient matter than in health. The
formed material which enters into the formation of the
liver-' cell' is soft, moist, and readily permeable to certain
nutrient matters. There is no cell-wall, but the outer
part of the formed material is gradually resolved into
soluble biliary matters, which pass down the ducts, and

252 THE MICROSCOPIST.

•

into amyloid and saccharine matters, which permeate the
walls of the vessels and enter the blood. To make up for
the disintegration of the outer part of the formed mate-
rial, new formed material is produced in the interior of
the cell from the germinal matter, and the germinal mat-
ter which undergoes this change is replaced by new germi-
nal matter produced from the pabulum that is absorbed.
If such cells and their descendants are bathed with im-
proper pabulum, and especially with substances which
render albuminous matters insoluble, or possess the prop-
erty of hardening them (as alcohol), they necessarily di-
minish in size, in consequence of the formed material be-
coming less permeable, less nutrient matter is taken up;
and, of course, as the formed material becomes hardened,
less disintegration takes place, the quantity of secretion,
which really consists of the products resulting from dis-
integration, is much diminished, and the amount of work
performed by the cell is reduced. Under the supposed
conditions the cells shrink in size and become more firm
in texture. Many gradually waste, and not a few die,
and at length disappear. These seem to be the essential
changes which slowly take place in the liver-cells in cir-
rhosis, and to these changes in the cells the striking
shrinking and condensation of the whole liver, so charac-
teristic of this disease, are due.

" From these observations it follows that disease may
result in two wrays — either from the cells of an organ
growing and multiplying faster than in the normal state,
or more slowly. In the one case the normal restrictions
under which growth takes place are diminished ; in the
other the restrictions are greatly increased. Pneumonia,
or inflammation of the lung, may be adduced as a strik-
ing example of the first condition, for in this disease mil-
lions of cells are very rapidly produced in the air-cells of
the lung, and nutrient constituents are diverted from
other parts of the body to this focus of morbid activity.

THE MICROSCOPE IN PATHOLOGY. 253

Contraction and condensation of the liver, kidney, and
other glands, hardening, shrinking, and wasting the mus-
cular, nervous, and other tissues, are good examples of
the second. The amount of change becomes less and less
as the morbid state advances, the whole organ wastes,
and the secreting structure shrinks, and at last inactive
connective tissue alone marks the seat where most active
and energetic changes once occurred. It is easy to see
how such a substance as alcohol must tend to restrict the
rapid multiplication of the cells if the process is too ac-
tive, and howr it would tend to promote the advance of
disease in organs in which rapid change in the cells char-
acterizes the normal state."*

Non-living pus-corpuscles are round and granular, about
•g^Q-oth of an inch in diameter. Dilute acetic acid renders
them transparent, and brings into view one or more nu-
clei, bright and sharply defined. Neutral alkaline salts
shrivel the pus-globules and caustic alkalies destroy them-
Besides the globules, pus often contains free nuclei, red
blood-corpuscles, epithelium, remains of connective tissue,
crystals of the triple phosphates, infusoria, etc. The in-
spissation of pus sometimes results in a cheesy metamor-
phosis or cassation, which has been called tuberculization of
pus (see the section on Fatty Degeneration, page 233).

In addition to pus-cells, there is in inflammation always
more or less fluid exudation, or inflammatory effusion.
This differs from the ordinary liquor sanguinis of the ves-
sels in health by containing a larger proportion of albu-
men and fibrinogenous substance, as well as an excess of
phosphates and carbonates. This exudation may be in-
terstitial when between the tissues and parts, parenchym-
atous if seated within the tissues so as to enlarge them,
or free if on free surfaces or natural cavities.

Serous exudations on free surfaces are called flux or

* The Physiological Anatomy and Physiology of Man, by Todd,
Bowman, and Beale. Part I.

254 THE MICROSCOPIST.

serous catarrh ; into serous cavities inflammatory dropsy ;
into tissues, inflammatory oedema ; under the epidermis,
serous vesicles, etc. A serous exudation containing albu-
men is found in many inflammations of the kidneys (al-
buminuria), and of the intestine (dysentery), etc.

Mucous exudation, or mucous catarrh, occurs oftenest
on mucous membranes, from the mingling of the epithe-
lial cells with the increased flow from the vessels. The
term " catarrh " came from the ancient idea that in a cold
liquid flows from the ventricles of the brain through the
ethmoid bone and nose.

In catarrhal inflammation of the mucous membrane
there is first hypersemia, then swelling of the membrane
and lymph-follicles with an increased production of epi-
thelial and mucous elements. The excessive growth of
bioplasm in these elements, according to Beale, changes a
simple mucous catarrh into a purulent one (Fig. 203).

FIG. 203.

Catarrh (purulent) of conjunctiva, a. Epithelium. 6. Connective tissue stratum of
the mucosa.— After EINDFLEISCH.

In catarrhal (lobular or broncho) pneumonia there is a
proliferation of the alveolar epithelium of lobules or
groups of lobules connected with those bronchial tubes in
which the catarrhal changes first began (Fig. 204).

If the patient recover, but the retained substances are
incompletely removed, a thickening of the walls may re-
sult, with the formation of a caseous nodule.

THE MICROSCOPE IN PATHOLOGY.

255

Desquamative catarrh of the kidneys, Fig. 205, hegins
with a granular cloudiness and falling off of the epithe-

FlG. 204.

Catarrhal pneumonia. One and a half of an alveolus. The tortuous capillaries of
the septa injected. Filling of the lumina with epithelial cells of the walls which
multiply by division. 1-300.— After BJNDFLEISCH.

lial lining of the uriniferous tubules, and an active prolif-
eration of the cells.

FIG. 205.

Transveise and oblique sections of catarrhal urinary tubuli. 1-500. — After EIND-

FLEISCH.

Rindfleisch calls vesicles and pustules produced by in-
flammation of the skin, an acute purulent catarrh of the
skin, in which a primary serous catarrh (vesicle) became
a purulent one (pustule). Eczema he terms a chronic

256

THE MICROSCOPIST.

catarrh of the skin, having its origin in hypersemia of the
papillary layer (Fig. 206).

FIG. 206,

^_ A

Vertical section through the skin after chronic eczema, a. Horny layer, b. Mucous
layer of epidermis, c. Pigmented stratum of cylindrical cells, d. Papillary layer, e.
Cutis pervaded by stripes of pigment. — After EINDFLEISCEI.

The stratum of Malpighi in the skin is analogous to
the softer epithelium of mucous surfaces, but catarrhal
processes in the skin are modified by the horny layer,
which is first destroyed in the instances referred to, and
then the multiplying epithelium cast off.

Fibrinous exudation consists of fluid from the hyperse-
mic vessels, which coagulates into fibres between whose
meshes serum is confined. Pus-corpuscles are generally
mixed with the exudation, constituting a fibrino-purulent
exudation. These occur principally on the surface of serous
membranes. The coagulated fibrin either glues the two
surfaces of the membrane together, or forms a slightly
adherent layer of membrane, in which the exuded cells
develop a true connective tissue (Fig. 207).

The false membranes which occur in pleuritis or peri-
carditis, generally of rheumatic origin, are examples of

THE MICROSCOPE IN PATHOLOGY.

257

this result. The formation of pus in serous cavities (em
physema, etc.) is well illustrated in Fig. 208.

FIG. 207.

,„,•,.••"

Adhesive inflammation. Diaphragmatic pleura, a. Contiguous muscular structure of
diaphragm, b. Subserosa. c. Serosa. d. Boundary of the serosa and the exudation, e.
Exudation. 1-400.— After RINDFLEISCH.

Croupous exudation differs from fibrinous by having its
origin in a peculiar metamorphosis of epithelium (Fig.

FIG. 208.

Purulent inflammation upon the serosa of the uterus, a. Serosa infiltrated with color-
less blood-corpuscles. 6. Surface secreting pus-corpuscles, c. Muscular structure. 1-500.
—After RINDFLEISCH.

209). Wagner has shown that this change in the cells re-

17

258

THE MICROSCOPIST.

suits in a delicate network, forming by its accumulation
a flat grayish-white croupous membrane, or isolated de-
posits. According to this view, the network of croup-

FIG. 209.

Fibrinous degeneration of pavement cells. — After E. WAGNER.

membrane occupies the place of epithelium. Other pathol-
ogists regard the network as analogous to the fibrinous
network of inflamed serous membranes. Croup of the

FIG. 210.

Croup of the trachea, a. The undermost layer of pseudo-membrane. 6. The base-
ment membrane, c. The subepithelial germinal tissue, d. Excretory duct of a mucous
gland, from which a clear mucus is evacuated and lifts off the pseudo-membrane. 1-1000.
— After RINDFLEISCH.

larynx and trachea shows a combination of catarrh and
pseudo-membranous exudation (Fig. 210).

THE MICROSCOPE IN PATHOLOGY. 259

Croupous pneumonia is generally an independent affec-
tion, while the catarrhal and interstitial forms of inflam-
mation of the lungs usually result from preceding bron-
chial or pulmonary lesion. The first stage is that of
engorgement, in which the capillaries dilate and coil so
as greatly to diminish the air capacity of the alveoli. In
the second stage, that of red hepatization (Fig. 211), the

FIG. 211.

Recent croupous pneumonia, a. Alveolar septa with injected capillary vessels. 6. The
exudation. 1-300.— After RINDFLEISCII.

exuded contents of the capillaries of the air-cells, red and
white corpuscles, and serum, are coagulated by the fibrin
into a solid body. The third stage is that of yellow or
gray hepatization, characterized by a greater proportion
of white blood-cells and their progeny, mingled with the
results of commencing fatty metamorphosis. Purulent
infiltration, or resolution, is sometimes called the fourth
stage of this disease. Here the fibrin melts down to a
soft amorphous gelatin, and the young cells undergo fatty
degeneration. Granular pigment also is mixed with the

260

THE MICROSCOPIST.

softened matters, and appears in the expectoration (Fig.
212). Instead of resolution, in which the exudation is
absorbed or cast out by the sputum, abscess, or gangrene,
or chronic pneumonia may result, though rarely.

Diphtheritic exudation accompanies a greater hyperremia
of the mucous surface than croupous inflammation, and
even of the submucous tissue, with a gangrenous separa-
tion of the infiltrated parts. Between the croupous and
diphtheritic forms of exudation there is every possible
transition.

FIG. 212.

Croupous pneumonia in a later stage of development. Melting down of the exudation.
Catarrhal desquamation of the alveolar walls. 1-300. — After RINDFLEISCH.

Buhl regards diphtheritis as a general disease, which
may be termed acute tissue necrosis, and is different from
inflammatory, typhous, scarlatinous, or other forms of
tissue necrosis.

The occurrence of fungi in diphtheritic exudation is
almost constant. The leptothrix buccalis is the most com-

THE MICROSCOPE IN PATHOLOGY.

261

mon form. Similar forms occur in croup-membrane.
Some suppose the fungus to be the primary cause of the
disease, but the decaying morbid matter may merely form
the habitat (see page 136).

RESOLUTION AND ORGANIZATION.

If the injury sustained by the tissue is not severe, or
by medical skill the vascular activity is lessened, the in-

Fic. 213.

0 O

f

Section through the border of a healing surface of granulation, a. Section of pus.
b. Tissue of granulation (germinal tissue) with capillary loops, whose walls consist of a
longitudinal layer of eel Is, decreasing in thickness from within outwards, c. Beginning
of the cicatricial formation in the deep layers (spindle-cell tissue), d. Cicatricial tissue.
e. Complete epithelial covering. The central layer of cells consists of serrated cells.
/. Young epithelial cells, g. Zone of differentiation. 1-300.— After RINDFLEISCH.

flammation may gradually subside or terminate in reso-
lution. The congestion diminishes, the emigration ceases,

262 THE MICROSCOPIST.

some of the cells undergo fatty degeneration and are ab-
sorbed, others are removed by the lymphatics, and the
tissue returns to its normal condition.

If the inflammation does not end in resolution, after a
diminution of intensity, there may be an organization of
many of the new cells into a form of fibrillated tissue, as
in the healing of wounds by uthe first intention," and in
many chronic inflammations of the liver, kidney, etc. In
this cicatricial tissue the cells become spindle-shaped or
elongated, with tapering ends. Sometimes, according to
Green, a sort of adenoid tissue results, consisting of
meshes of fibrillated material inclosing lyrnphoid cells.

After suppuration, organization takes place by granu-
lation or the "second intention" It takes place wherever
the injured tissue presents a free surface to the air, as in
an ulcer, or in a wound left open, etc. (Fig. 213). The
young cells of the superficial layer develop into granula-
tion tissue, which forms little papilliform nodules or granu-
lations. The form of these granulations seems determined
by the new capillary bloodvessels which grow rapidly in
the new tissue. The deeper layers of the tissue gradually
develop into fibrillated tissue, while the cells on the sur-
face of the granulations and transuded liquid from the
vessels are discharged as pus. The first formation of epi-
thelium seems to consist of pus-corpuscles not thrown off,
yet the influence of the neighboring normal epithelium is
seen in the proliferating margins, as w^ell as in the effect
of skin-grafting, as it is called, on the surface of an ulcer.
The new epithelium alwa3Ts remains thin and dry.

PATHOLOGICAL NEW FORMATIONS.

Increased nutrition leads not only to the enlargement
of the component elements of a tissue, but also to the
production of new elements by proliferation of bioplasm
constituting new formations. These may be either in-
flammatory or non-inflammatory growths, occurring as

THE MICROSCOPE IN PATHOLOGY. 263

tumors, infiltrations, or numerical hypertrophies, the lat-
ter differing from simple hypertrophies, or increased size
of the elements of tissues, by increase in the number of
the elements, as of the muscular fibres in hypertrophied
muscle, etc.

New formations are in all cases the direct product of
pre-existing cellular elements, and their development re-
sembles more or less the normal tissues. In other words,
every pathological growth has its physiological prototype.
If it is similar in structure and development to the tissue
from which it originates, or in which it is situated, it is
called homologous ; when it differs, heterologous.

The elements from which new growths most frequently
originate are those of the common connective tissue with its
bloodvessels and lymphatics. This tissue must be distin-
guished from formed connective substances, as bone, ten-
don, cartilage, etc. Two kinds of cells are found in this
tissue, — the connective tissue cells, which are stable, and
the mobile cells, which are probably wandering leucocytes.

The first result of the abnormal activity of these cells is
to produce a new tissue, — embryonic or indifferent tissue, —
composed of small roundish cells, about o-o'or tb of an inch
in diameter. This tissue afterwards develops into tissue
of permanent growth, resembling the immature connective
tissue of the embryo, and like that capable of becoming
fibrous tissue, cartilage, bone, etc.

Next to common connective tissue, the epithelia, surface
and glandular, are the elements from which new forma-
tions most frequently originate, and such growths gener-
ally resemble epithelium.

From the higher animal tissues, muscle and nerve, new
growths are rare, if, indeed, they really occur at all.
Beale says "the fully formed anatomical elements of a
normal tissue could not give origin to a morbid growth."

The term malignancy is applied to a property possessed
by many tumors of recurring after removal, of infecting

264 THE MICROSCOPIST.

neighboring lymphatic glands, and of reproducing them-
selves in distant organs. It is not confined to carcinomas
or cancers, since many sarcomas are just as malignant.

Pathological new formations are subject to retrogressive
changes similar to those of physiological tissues. Deficient
supply of blood is followed by fatty degeneration, with its
varied terminations, — softening, caseation, and calcifica-
tion. Pigmentary, colloid, and mucoid degeneration may
also occur, or inflammation. In addition, one form of
tissue may be transformed into another, especially of the
same group, as of connective tissue elements. Thus can-
cers may form in cicatrices and tumors of various kinds,
sarcomas in fibromas, etc.

Pathological new formations have been variously classi-
fied. For convenience of the student we divide them as
follows:

1. Pathological formation of cells

2. Pathological growth of higher animal tissues.

3. Pathological growths of connective tissue origin.

4. Pathological growths of epithelial origin.

I. NEW FORMATION OF PATHOLOGICAL CELLS.

We have already stated that proliferating cells, either
tissue-cells or wandering leucocytes, produce abnormally,
first, an embryonic or indifferent tissue. This seems iden-
tical with granulation tissue (page 262). From it various
new growths proceed. The cells multiply as in normal
tissues, by division, budding, or endogenous formation
(page 125). Cell division affects the entire cell nucleus,
nucleolus, and bioplasm. It is generally accomplished
quickly, judging from experiments on the warm stage of
the microscope (page 42). Budding is a variety of self-
division, in which a small portion of bioplasm is protruded
and separated so as to become an independent cell. In
exogenous cell formation the nucleus, after previous di-
vision of the nucleolus, divides into two or more nuclei.

THE MICROSCOPE IN PATHOLOGY.

265

In the giant cells, so called, the nuclei number ten to fifty
or more. Physiologically these occur in bone marrow,
where they are regarded as transformed osteoblasts, and
pathologically in granulation tissue and many tumors.
In soft, yielding tissues their form is roundish, but in
fibrous tissues the giant cells have peripheral processes
(Fig. 214).

FIG. 214.

Giant cells, a. Koundish (Virchow). b. With processes. From a muscular tumor
(Billroth).— After BJNDFLEISCH.

Rindfleinch has pointed out a cell-formation in nucleus-
bearing protoplasm, where apparently free nuclei are im-
bedded in homogeneous substance, but
reagents show a differentiation of the FlG- 215-

protoplasm, so that to each nucleus
belongs a small round cell. This is
different from giant cells, and occurs
in many sarcomata and cancers (Fig.
215).

Most cells are capable of increase.
The movable and fixed cells of con-
nective tissue, young bone, and carti-
lage cells ; the youngest layers of epi-
thelial cells, either of the surface or
glandular; the nuclei of capillaries, of the sarcolemma,

Nucleated protoplasm.
Fragment from a granula-
tion.

266 THE MICROSCOPIST.

etc., may any of them become points of departure for
pathological new formations. The youngest formed, or
embryonic cells, may be developed like the tissues of the
embryo, may become connective tissue cells, bone-corpus-
cles, muscle-fibres, and, according to some, true epithe-
lium, etc., or cancer-cells, sarcoma-cells, etc. The cells,
however, which rise from various tissues usually give
origin to definite new formations. Thus epithelial forma-
tions arise from epithelial tissue ; connective tissue forms
from connective tissue, etc.

II. PATHOLOGICAL GROWTHS OF HIGHER, ANIMAL TISSUES.

1. Muscular Tissue. — a. Striated. Virchow, and after
him Billroth and others, have shown that the elements
of the more highly organized tissues, as the nervous and
muscular, are rarely imitated pathologically.

Systematic writers term striated muscular tumors rhab-
domyoma, or true myoma. The few instances referred to
consist of a few fibres mixed with other tissues in cystic
tumors of the ovary, testicle, etc.

b. Smooth muscular-fibre tumors, or leiomyoma, — fibroid,
in the narrower sense, — occurring most frequently in the
body of the uterus, either as submucous, intramural, or
subperitoneal tumors, are so similar in their elements to
the ordinary fibroma as not to be distinguished from it.

2. Nervous Tissue. — The term neuroma is applied to a
fibrous tumor on a nerve. It is quite doubtful if the term
is applicable. The cases recorded are small, roundish,
hard tumors, occurring in the course of nerves, and nod-
ules on nerves at the end of amputation stumps. They
consist, however, of increased vascular connective tissue
separating the nerve-fibres. Rindfleisch refers to a case
which he deems a true neuroma. He says it is the first
example of a genuine one, yet states that it may be a
hypertrophied ganglion of the sympathetic.

THE MICROSCOPE IN PATHOLOGY.

267

III. PATHOLOGICAL GROWTHS OF CONNECTIVE TISSUE
ORIGIN.

a. Common Connective Tissue Type.

1. Fibroma is a generally innocent growth, consisting
essentially of fibrous tissue (Fig. 216). Fibromata are

FIG. 216.

Transverse section of a fibroma of uterus. 1-300. a. Isolated cellular elements, b. An
unravelled fasciculus of the fibroma. 1-500.— After RINDFLEISCH.

usually circumscribed, rarely diffused, and are composed
of interlaced fibres and cells, like cicatricial tissue. The
common fibroid is so dense that in cutting it creaks under
the knife.

Fibromata occur on the trunk and extremities, proceed-
ing .from the skin (as elephantiasis tuberosa, etc.), from the
subcutaneous and intermuscular connective tissue, from
fascia, periosteum, bones, and bone-marrow ; in the uterus
and its vicinity, in subserous tissue, in submucous tissue,
especially of the nose and throat ; in nerves (as common
neuroma and the subcutaneous painful tumor, or irritable
tumor, as it is called) ; in glandular organs, as the mammae
and kidneys, etc. For the most part fibromata grow very
slowly, but they are often combined with other forms.

268

THE MICROSCOPIST.

2. Areola fibroma, or fibro-cellular tumor, consists of
bundles of connective fibres with spaces containing serous
or mucous fluid. It occurs in circumscribed or diffuse
form. The circumscribed is found in the skin and sub-
cutaneous tissue, especially of the scrotum, labia majora,
around the vagina, in internmscular connective tissue,
periosteum, uterus, mammae, etc. The diffuse occur of ten-
est in the skin as soft warts (fibroma molluscum, Fig. 217);

FIG. 217.

Fibroma inolluscum. J. Completed tissue, after Virchow. 2. Immature condition.
Formation of clefts in the parenchymatous islands. 1-200. At a, the lumen of a vessel.
—After RINDFLEISCH. •

as elephantiasis of the scrotum, prepuce, labia, clitoris, of
the extremities, nose, etc. ; and as polypi in the submu-
cous tissue of the pharynx, nose, uterus, etc.

. • , ;. b. Mucous Tissue Type.

1. Myxoma, or mucous tumor, occurs either pure or
mixed with other tissues. It consists of a mucous basis-
substance, with stellate or spindle-shaped anastomosing
cells (Fig. 218), or in young myxomas, of small round
cells, like mucous corpuscles. Myxoma form rapidly-
growing, soft, knotty swellings, which may be mistaken
for soft cancers. They may be classed with benign tu-
mors, and do not return after thorough extirpation.

THE MICROSCOPE IN PATHOLOGY. 269

Myxomata occur in subcutaneous and intermuscular
connective tissue, in fasciae, medulla of bones, and in the
interior and vicinity of glands. A myxoma of the pla-
centa has been described as a vesicular mole, consisting
in a hypertrophy of the mucous tissue of the tufts of the
chorion, producing tumors, varying to the size of a cherry

FIG. 218.

Hyaline inyxoma of the subcutaneous connective tissue in the neighborhood of the
angle of the jaw. 1-300.— After RINDFLKISCH.

or larger ; the whole mass may attain the size of a man's
head. The fetal development in such a case varies ac-
cording to the mass of the tumors.

c. Vascular Connective Tissue Forms.

1. Angioma, or vascular tumor, is composed of blood-
vessels held together by a small amount of connective
tissue. The angiomata include the various forms of nsevi,
the erectile tumors, and aneurism by anastomosis.

(1.) Capillary angioma, nsevus vasculosus, or teleangiec-
tasia, is generally congenital. It occurs oftenest on the
skin, in the papillary layer (mole, mother's mark, etc.),
although it may occur in other structures. It may vary
in size from that of a millet-seed to the occupancy of the
entire face or extremity. It is flat, lobed, generally bluish
or dark red, arid consists of tortuous, varicose, or aneuris-
mal capillary vessels and wavy connective tissue.

270

THE MICROSCOPIST.

(2.) Cavernous or venous angioma, erectile tumor, or
aneurism by anastomosis, is generally round, from the
size of a bean to that of a walnut. It is similar in struc-
ture to the erectile cavernous tissue of the penis and clit-

FIG. 219.

The substance of the cavernous tumor in full development. 1-300. From a cavernous
tumor of orbit.— After RINDFLEISCH.

oris, consisting of a network of fibres containing blood
(Fig. 219). They are generally of a bluish color. Venous
angiomata, consisting mainly of enlarged and tortuous
veins, are often seen as internal or external heernorrhoidal
tumors.

(3.) Arterial angioma is sometimes met with, especially
in the branches of the temporal and occipital arteries.

(4.) Lymphatic angioma is a similar dilatation of the
lymphatic vessels, and has been principally noticed in
connection with elephantiasis. Lymphangiomata of the
kidneys and of the skin have also been described.

2. Thrombosis is a coagulation of the blood in the ves-
sels during life, from impeded blood-flow or changes (as
inequalities) in the, walls of the vessels. It depends on
separation of the fibrin from the blood. Dr. Schmidt has
shown that the blood-corpuscles contain an albuminoid

THE MICROSCOPE IN PATHOLOGY.

271

substance (globulin, fibrino-plastic substance), which en-
ters into union with a similar (fibrinogenous) substance,
so as to form fibrin, the molecules of which have a great
attraction for each other, producing a characteristic mi-
croscopic network of round filaments.

Thrombi must not be confounded with the coagula
found in the dead. If the death-struggle has been long
coagula are generally found in the right side of the heart,
often extending into the pulmonary artery. A thrombus
is lighter, firmer, and drier than a coagulum, and is often
made up of concentric layers.

Cross-section through a thrombus by ligation of the crural artery, thirty-seven days
old ; hardened in alcohol, treated with dilute acetic acid, and then with a little ammonia-
a. Capillaries, b. The cell-net of the colorless blood-corpuscles. In the basis-substance
the contours of the red blood-corpuscles. — After RINDFLEISCH.

A thrombus once formed either organizes or softens.

If it organizes, the thrombus is gradually changed into
connective tissue. This is by virtue of the vital power
of the bioplasts, or white corpuscles. Thrombi have been
produced in animals by ligation, and cinnabar injections
into the blood have shown the wrandering leucocytes,
carrying cinnabar, at work in the blood-clot. They send
out processes in various directions, which touch each
other and form a more delicate net with nuclei at the
points of intersection (Fig. 220).

272

THE MICROSCOPIST.

SOOD after vessels are formed in the thrombus, which
give it an organlike connection with the body, as other
pathological new formations. These vessels may widen
and become cavernous, as in Fig. 221, and as the walls
become thinner and finally disappear the thrombus ceases
to exist.

FIG. 221.

a

From the cross-section of an arterial thrombus of three months, a. Media, only the
innermost layers. 6. Boundary lamella of the media and intiuia. c. Intinia. d. Bound-
ary of intiiaa towards the thrombus, e. Thrombus, /. Lurnina of vessels. Distinct
epithelium. 1-300.— After RINDFLFISCH.

The softening of the thrombi is a dangerous process.
Fragments may be carried from the radicles of the vena
cava through the right heart to the lungs ; from the radi-
cles of the pulmonary veins through the left heart to the
various organs of the body ; or from the radicles of the
portal vein to the liver. Such particles may occlude the
vessel in which they are found, producing embolism,, the
results of which may depend on the mechanical obstruc-
tion to the circulation (anaemia and softening), or on
the irritating or infective properties of the emboli (pyae-
mia).

a. Adenoid or Eeticular Connective Type.

1. Lymphoma. — This is a new formation of lymphatic
or adenoid tissue, and is generally found as small tumors
or infiltrations, consisting of rounded bright nuclei, and

THE MICROSCOPE IN PATHOLOGY.

273

small cells, like leucocytes, lying in semifluid or fibrous
intermediate substance. Lymphomata occur in typhoid
fever in the small intestine, in the mesenteric glands, and
liver. Lymphatic tissue always consists of a reticulum of
branched cells, within the meshes of which the lymphatic
corpuscles are contained. It is closely allied to embry-
onic tissue, and is easily influenced by any irritation
whatever to excessive development. Inflammatory states

FIG. 222,

From the section of the cervical gland of a dog, swollen to the size of a hazolnut after
artificially produced inflammation of the lips. 1-500. After Billroth. Connective tissue
septum. Sinus termiualis. Border of lymph alveoli.— After RINDFLEISCH.

of the organs from which the glands receive their lymph
produce suppurative, cheesy, and indurated lymphade-
nitis (Fig. 222).

18

274 THE MICROSCOPIST.

The adenomata are generally innocent. The glands
which are most prone to increased growth are the cervical,
submaxillary, axillary, inguinal, and abdominal glands.
Sometimes several glands unite so as to form large lobu-
lated tumors. The enlargement of the spleen in ague is
probably of this nature. Leucocythgemic new formations
occur generally in the spleen, the lymph glands, and per-
haps the medulla of bones.

2. Tubercle is an infiltrated or nodular new formation,
generally multiple, or miliary, non-vascular, round or ir-
regular, made up of large and small nuclei, indifferent
cells, and giant cells, imbedded in reticular tissue. After
long induration it passes into cheesy atrophy, or into soft-
ening, and produces not only local affections but also con-
stitutional disease (tuberculosis and scrofulosis). It was
formerly considered to be a specific non-inflammatory
growth originating spontaneously, and characterized by a
regular succession of changes, first gray and translucent,
then opaque, and finally caseous. Modern histologists re-
gard it as due to infection from the absorption of the
products of inflammatory processes. Caseation after fatty
degeneration (page 233) may become a focus of self-infec-
tion, so that caseation and tuhercle may occur side by
side. The nodules of tubercle are sometimes microscopic
in size, as in the liver or meninges of the brain. When
they reach the size of a millet-seed they are termed mili-
ary tubercles (gray tubercle, semi-translucent granulation).
If as large as a pea, cherry, egg, etc., they are large, tuber-
cles or conglomerate nodules. Still later they are known
as yellow tubercles, from their being yellow and cheesy in
the centre.

In Fig. 223 is a view of two broncho-pneumonic depots,
the size of a millet-seed, illustrating a pseudo-tuberculous
condition.

See also page 254, where catarrhal pneumonia is stated
to precede a caseous nodule.

THE MICROSCOPE IN PATHOLOGY.

275

In contrast with this Fig. 224 shows the deposit of
miliary tubercle as it occurs in tubercular meningitis.

FIG. 223.

Two smallest broncho-pneumonic depots. Tubercle granulation of Laennec. a, a.
The luminaof two adjacent small bronchi, the caseous secretion partially fallen out;
the walls infiltrated with cells and directly going over into catarrhal infiltration of the
surrounding parenchyma. By the course of the elastic fibres we may recognize every-
where how large the number of infiltrated alveoli is. 6, 6, b. Bloodvessels. 1-100 mm. —
After EINDFLEISCH.

The inflammatory growth originates in the perivascular
lymphatic sheaths which inclose the small arteries of the

276

THE MICROSCOPIST.

pia mater. The cells of the sheath multiply, and numer-
ous gray nodules are produced around the vessel.

Microscopically, Wagner describes fresh miliary tuber-
cle as consisting of one or more (from four to six gener-
ally) rounded follicles or nodules, each composed of a

Vertical section through the pia mater and the contiguous portion of the cortex of
brain in tubercular meningitis, a, a. A larger vessel of the pia mater whose entire
sheath is intiaiumatorily infiltrated. 6,6. Lymph-spaces of the pia mater with com-
mencing tubercular proliferation of the endothelia. c. Miliary tubercle of the pia mater.
d. Outermost layer of cortex of brain infiltrated with round cells, e. Normal brain-sub-
stance. /,/. Proper cerebral vessels in a state of tuberculous degeneration. — After RIND-

FLEISCH.

reticulum and cellular elements. The latter are free nu-
clei, cells like leucocytes with one or two nuclei, and in
the centre of the follicle one or more polynuclear giant
cells. The latter are granular and branching, with 20 to
100 rounded and comparatively large nuclei. In addition
there are cells of intermediate size, epithelial-like, rounded,
and finely granular. Tubercle always occupies the place
of normal tissue, which is either wasted or pushed aside
by it.

There may be atrophy or necrosis of the elements of
tubercle, after which cornification may transform it into
a hard horny mass. Eesorption rarely occurs, but calci-

THE MICROSCOPE IN PATHOLOGY. 277

fication will sometimes produce stony masses, which are
occasionally laminated. Most often softening or liquefac-
tion occurs simultaneously with cheesy metamorphosis,
leading on mucous surfaces to tuberculous ulcers, and in
the parenchyma of organs to tuberculous cavities or ab-
scesses.

e. Neuroglia or Nerve-cement Type.

1. Glioma is an increase of the elements of the finely
granular and reticular tissue or connective substance of
nerve. The nervous elements do not participate in it.
Glioma formerly went under the name of sarcoma, being
considered a variety of round-celled sarcoma, but the lo-
cality and origin of these tumors entitle them to separate
consideration. They are generally cerebral, and produce
symptoms of pressure or irritation. In the retina they
may begin as a white nodule, which grows until it may
project from the orbit as a large fungous tumor. Accord-
ing to the relative proportion of cells, intermediate sub-
stance, and vessels, they are divided into soft, hard, and
teleangiectatic gliomas. Gliomas are of very slow growth,
and may become metamorphosed by haemorrhages, fatty
degeneration, and cystoid softening. Healing may be
possible through fatty metamorphosis.

/. Type of Fatty Tissue.

1. Lipoma. — A general formation of new adipose tissue,
hereditary or acquired, is termed obesity. A local and cir-
cumscribed formation is a lipoma or fatty tumor. The
connective tissue unites the fat-cells in masses and lobules,
and forms a distinct capsule. Lipomata are sometimes
pedunculated. Their growth is slow, and although they
may attain considerable size they are perfectly benign
tumors.

Xanthoma, or xanthelasma, are small yellowish fatty
tumors of the skin, generally of the face or eyelids. They

278 THE MICROSCOPIST.

are sometimes nodular, like millet-seeds or grains of wheat,
isolated or in groups.

g. Cartilage Type.

1. Enchondroma or Cartilaginous Tumor. — Like carti-
lage, this consists of cells and intercellular substance, the
latter being hyaline, fibrous, or mucoid. The cells are
often spindle-shaped or stellate. Enchondromata rarely
develop from cartilage, but from bone and connective tis-
sue. A large majority have their seat upon bones, espe-
cially at the diaphyses of the long bones. They are usu-
ally single, except on the fingers and toes, where they are
often multiple. An ossifying enchondronia is called osteo-
chondroma. The enchondromata, especially those which
originate from cartilage, may be regarded as benign, yet
encapsulated forms originating from bone or connective
tissue are often injurious from the rapidity of their growth.
The softer forms, such as occur in the medulla of bone,
are sometimes malignant.

h. Type of Bone Formation.

1. Osteoma. — An osseous or bony tumor. An outgrowth
from pre-existing bone is an exostosis or osteophyte. Such
outgrowths proceed from the periosteum, the articular
cartilage, or the medulla. In the latter case they might
be properly termed enostoses. These are homologous tu-
mors, since they are similar in structure to the tissue in
which they are found. The osteomata, however, may be
heterologous, as growing from connective tissue or carti-
lage apart from bone. They are of two kinds : 1. The
ivory or hard tumors, in which there is a marked absence
of cancellated bony tissue. 2. The soft or cancellous,
which are spongy. The medullary cavities are sometimes
quite large.

Osteomata are innocent tumors. Those osseous growths

THE MICROSCOPE IN PATHOLOGY.

279

which exhibit malignancy are ossified sarcomata or ossi-
fied cancers.

i. Other Forms Analogous to Connective Tissue Type.

1. Sarcoma. — Fibro-plastic or fibro-cellular tumor. It-
belongs to the group of connective substance tumors by
some of its affinities, but is to be distinguished by the
greater development of its cellular elements. All the
sarcomata consist of embryonic connective tissue, and the

FlG. 225.

Round-celled sarcoma, a. Vascular lumina. 6. Parenchyma partly brushed out, so
that the hardened basis-substauce appears as an elegant network. 1-300.— After RIND-
FLEISCH.

several varieties are dependent on the size and shape of
the cells and the nature of the intermediate substance.
They include what are termed recurrent, fibroid , and mye-
loid tumors.

(1.) Round-celled sarcoma is allied to granulation and
embryonic tissues (page 262).

a. The granulation-like round-celled sarcoma, of soft con-
sistence, containing embryonic cells in a homogeneous or
finely granular intercellular substance.

280

THE MICROSCOPIST.

b. The lymphatic glandlike round-celled sarcoma exhibits
round cells in a delicate network of fibres among wide
thin-walled capillaries (Fig. 225).

There are several varieties of these lymphadenoid sar-
comas, as the lipomatous sarcoma, in which the cells by
infiltration are transformed into fat; the mucoid sarcoma,
from mucoid metamorphosis ; and the large-celled round-
celled sarcoma, which seems almost epithelial in its char-
acter of cells, with a large-meshed network. This tumor
is soft and brainlike, and may be easily confounded writh
the following:

c. The Alveolar Round-celled Sarcoma. — This has a great
resemblance to cancer, and has been called sarcoma carci-
nomatodes. It consists of groups of cells not connected

FIG 226.

Alveolar round-celled sarcoma, pigraented. b. Alveolus from which the ball of round
cells has fallen out. c. Vessel with pigmented eridothelia. d. Piginented round cells.
e. Spindle cells forming a stroma.— After RINDFLEISCH.

by basis-substance, but held in alveoli or clefts of connec-
tive tissue. The cells resemble epithelium. An exceed-
ingly malignant variety has been called pigmentary cancer
(Fig. 226).

(2.) Spindle-celled sarcomata are divided into — a, small-
celled spindle^elled sarcomata (Fig. 227), which resembles

THE MICROSCOPE IN PATHOLOGY. 281

the spindle-celled tissue of recent cicatrices ; b, large-celled
spindle-celled sarcomata, in which the cells attain an ex-
cessive development (Fig. 2i!8); and c, the pigmentary sar-
comata.

FIG. 227.

Spindle-celled scarcoma. Gaping vascular lamina. The cell lines are divided partly
longitudinally, partly transversely. 1-300. — After RINDFLEISCH.

(3.) The giant-celled sarcomata, called also myelo-plastic
and myeloid sarcomas, contain large cells, with numerous
nuclei and nucleoli in a finely granular substance (Fig.
229). These occur usually on bones.

Sarcomata are rarely found in internal organs. They
usually arise from common connective tissue, and the
influence of locality on them is obvious. Thus on the
surface of bone we have osteoid sarcomata, pigmented
sarcomas in the skin and choroid, soft and gelatinous
sarcomata in the glands, etc. Complete cure sometimes
follows extirpation, but at other times there is a recur-
rence in the cicatrix, giving rise to the term recurring
fibroid. Like other tumors they may inflame or become
atrophied, or fatty metamorphosis, calcification, etc., may
occur in them.

2. Syphiloma. — Gumma-syphiliticum. Gummy tumor.

282

THE MICROSCOPIST.

This is a new formation, depending on constitutional
syphilis. Its essential elements resemble leucocytes im-
bedded in connective tissue which is poor in vessels.
It exhibits many transitional forms to granulation tissue

FIG. 228.

Large-celled spindle-celled sarcoma. — After VIRCHOW.

and sarcomata. Atrophy or fatty metamorphosis of the
cells may produce cavities or caverns and cicatricial marks
on the surface, leading to deformities (Fig, 230).

THE MICROSCOPE IN PATHOLOGY.

283

3. Lupus consists of nuclei and cells, forming a diffuse
or nodular infiltration of the corium of the skin, generally

FIG. 229.

Giant cells, a. Roundish (Virchow). 6. With processes. From a muscular tumor
(Billroth).— After RINDFLEISCH.

of the face, and sometimes of the bordering mucous mem-

FlG. 230.

Syphilis ot liver, a. Left. b. Right lobe of liver, cc. Connective tissue sheath, which
penetrates the organ in the direction from the porta to the lig. suspensorium, and con-
tains gummata. 2-1.— After RINDFLEISCH.

brane. Rindfleisch considers it to begin with a luxuriant

284 THE MICROSCOPIST.

cell proliferation in the interstitial and encapsuling con
nective tissue of the sebaceous and sweat glands (Fig.
231). If the skin appears normal, or there is a moderate
scaling till the lupus elements are resorbed, and there
is left behind a smooth or radiating cicatrix, it is called
lupus non exedens. Lupus exedens, or rodens, is ulcerative.
4. Lepra — Elephantiasis Grcecorum. — Leprosy formerly
prevailed all over Europe, but is now confined in that di-
vision of the globe to Iceland, Norway, the northern

FIG. 231,

Lupus. Section showing the transition of the healthy skin into the highest degree of
infiltration, a. Acinous alveoli, b. Germinal tissue of the lupus nodule, c. Metaplastic
hair-follicle and sebaceous gland. 1-10.— After RINDFLEISCH.

provinces of Russia, and the borders of the Caspian and
Mediterranean seas. It still remains in Asia Minor,
Arabia, Egypt, India, China, and the Hawaiian Islands.
It is rarely cured, and generally destroys life by some sec-
ondary affection, as anaemia, diarrhoea, pneumonia, menin-
gitis, etc.

L. tuberculosa, the common form, is characterized by a
nodular formation in the skin and other organs. The
microscope shows these to consist usually of round granu-
lar cells with granular albuminous intercellular substance
(Fig. 232).

These nodules soften and form ulcers, yielding a thin
sanious pus, which dries to a brownish crust.

In L. ancesthetica the nodules are absent, but there is

THE MICROSCOPE IN PATHOLOGY.

285

found on the spinal cord a thick yellow dense mass of a
diffuse leprous new formation, producing first paralysis of
sensation, and later of motion, with mummification and
necrosis of the skin, gangrene of fingers and toes, etc.
Sometimes both forms are combined in the same patient.

FIG. 232.

a. Lepfa tissue, after Virchow. Cells in division.— After RINDFLEISCH.
IV. PATHOLOGICAL GROWTHS OF EPITHELIAL ORIGIN.

1. Papilloma — Papillary or Villous Tumor. — Papillom-
ata are analogous to the vascular papillee of the skin,
villi of the intestine, etc., and are composed of a vascular
connective tissue body or basis, covered with epithelium
(Fig. 233).

They form therefore a connecting link between the epi-
thelial and connective tissue types. The quantity of epi-
thelial growth varies in different papillomata In the
skin it is abundant, and the superficial layers are hard
and stratified, but in mucous membranes it is thinner and
softer, while in serous membranes it is only a single layer.
Papillomata of the skin include warts and horny growths ;

286

THE MICROSCOPIST.

those of mucous membranes are often classed as mucous
polypi. The latter occur on the tongue, in the larynx
and nose, on the cervix uteri, etc. In the bladder and
intestine they are very vascular and produce profuse

FIG. 233.

A hyperplastic papilla of the cutis, together with epithelium, from the environs of
cancroid of the lip. — After RINDFLEISCH.

haemorrhage. Here they are often mistaken for villous
epithelioma, since the symptoms are similar and scarcely
distinguishable till after death. In the papillomata the
epithelium is homologous, being situated only on the sur-
face, and in no case growing within the connective tissue
basis. In the epitheliomata it is heterologous and is met

THE MICROSCOPE IN PATHOLOGY. 287

with in the subjacent connective tissue. Yet a simple
papilloma may develop into an epithelioma.

2. Adenoma, or Glandular Tumor. — This forms sharply
defined, and generally encapsuled, knots of new-formed
glandular tissue. Its structure resembles that of race-
mose or tubular glands, and consists of numerous saccules
or tubes lined with squamous or cylindrical epithelial
cells. These are grouped together, being separated by a
small amount of vascular connective tissue.

As sarcomata, myxomata, etc., occurring in glandular
organs, have more or less glandular tissue, it is often dif-
ficult to see which predominates, hence the terms adeno-
sarcoma, adeno-myxoma, etc.

Adenomata of the skin vary in size to that of an egg,
and originate from sweat or sebaceous glands. Rlnd-
fleisch considers lupus to be of this nature (see Lupus).

Adenomata of mucous membranes form mucous polypi,
which are usually broad, rarely pedunculated, and grow
from the size of a bean to that of a hen's egg. The sur-
face of such tumors is like that of the mucous membrane,
but internally it may be fibrous and vascular, or even
cystic. They occur on all mucous membranes, but often-
est in the nasal cavity, rectum, and uterus. The conse-
quences of these adenomata depend on their size and
anatomical relations. Thus they may form obstructions
and give rise to catarrh and haemorrhage.

Adenomata of glands occur more especially in the
mamma, parotid, prostate, liver, and thyroid. Adenoma
of the thyroid is known as goitre. Adenoma of the
mamma (Fig. 234) is called by Bill roth a " true epithelial
glandular carcinoma." The only difference between it
and a genuine epithelioma or carcinoma appears to be
that the proliferatien of the epithelium is confined to the
dilated glandular cavities, instead of infiltrating the sepa-
rating walls, as in cancer.

Some ovarian cysts — myxoid or colloid cystomata —

288 THE MICROSCOPIST.

(page 239) belong to the adenomata. They proceed from
the rounded or elongated saccular epithelial masses which
form the processes of the Graafian follicles.

Adenomata are usually benign formations, but have a
tendency to pass into cancer.

3. Carcinoma, or Cancer. — The term cancer is applied
to an epithelial new formation which rnay occur as a
tumor or infiltration in any tissue or organ, which is quite

Adenoma mammae. Genuine epithelial carcinoma (Billroth). 1-300.— After RINDFLEISCII.

malignant, but which is generally (not always) chronic in
its course. Its cells are not peculiar, being similar to
other physiological cells, but by their rapid multiplication
and metamorphoses are followed by destruction of the
affected parts of the organ, and finally of the organ itself.
It usually returns after extirpation, or it may secondarily
affect internal organs. We have seen, page 264, that ma-
lignancy is by no means an exclusive property of cancers,
since other new formations may be equally malignant.

Cancer occurs in various forms, as scirrhus, encephaloid,
and colloid. Some consider epithelioma also to be a form
of cancer, but as it is not as malignant as other forms,
and is characterized by its local growth, it may be best
considered separately as cancroid rather than true cancer.

THE MICROSCOPE IN PATHOLOGY. 289

Histologically, the forms of cancer resemble each other
in consisting of cells of an epithelial type, without inter-
cellular substance, grouped in irregular nests within the
alveoli of a fibroid stroma (Fig. 235).

The differences between various forms of carcinoma
are chiefly dependent on the greater or less proportion of
cello and fibrous stroma. The deposit of pigment, form-
ing melanotic cancer, as it is termed, may also be a cause

FIG. 235.

a

Brushed-out stroma of soft glandular cancer, a. Section of cylinder of cancer-cells.
b. Trabecuhe of the stroma. c. A single spindle-cell, which extends from one trabecula
to another, and by the separation of basis-substance along its protoplasm gives the im-
pulse to the formation of a new trabecula of the stroma. d. Round-celled infiltrate in
the interior of the trabeculae of the stroma. 1-300.— After RINDFLEISCH.

of variety ; so also ossification of the stroma (osteoid cancer)
and the multiplication and enlargement of the vessels, as
in fungus hcematodes ; but for the purposes of study the
three forms referred to are sufficiently characteristic.

A difference of opinion exists as to the origin of the
epithelial-like cells in cancers. Billroth and others regard
them as starting only from pre-existing epithelium, while
Yirchow, Bindfleisch, etc., consider that they may be also

19

290

THE MICROSCOP1ST.

derived from connective tissue. It is not at all improba-
ble that any kind of bioplasts, as Beale maintains, may
form such growths by rapid proliferation, although the
weight of evidence justifies us in regarding epithelial
structure as the most frequent origin. The two follow-
ing figures from Rindfleisch shows two different forms of
origin in carcinoma of the liver. Fig. 236 shows the nor-

FlG. 236.

Carcinoma hepatis. The production and structure of pigmented radiary cancer. The
liver-cell net forms the first foundation of the stroma, while the cancer-cells are de-
posited in the lumen of the vessels. 1-400.— After RINDPLEISCH.

mal liver-cell as furnishing the first foundation of the
strorna, while the cancer-cells are found in the vessels.
The liver-cells are generally pigmented. The spindle-
formed and stellate cells which are also seen in the more
delicate trabeculse of the stroma have nothing to do with
the liver-cells. In common cancer of the liver the vessels
form the origin of the stroma, while the cancer-cells come
from the liver-cells (Fig. 237).

THE MICROSCOPE IN PATHOLOGY.

291

(1.) Scirrhus. — Hard, fibrous, or chronic cancer. This is
characterized by the large amount of its stroma and its
chronic growth. At the external surface of a scirrhus
tumor the microscope shows cells of indifferent, or granu-
lation, tissue infiltrated among the muscular or adipose
tissue of the part affected. At a little greater distance
within these cells have developed into nests of cancer-

FIG. 237.

Carcinoma hepatis. The production and structure of diffuse medullary cancer. The
vascular network forms the first foundation of the stroraa, while the liver-cells are con-
verted into cancer-cells, a. Normal liver-cells, c. Parenchymatous inflammation, b.
Nests of cancer-cells, v. Vena centralis. 1-400. — After EINDFLEISCH.

cells, while the interstitial inflammation has produced an
abundant stroma from the growth of pre-existent connec-
tive tissue, the trabeculae of which are pressed asunder
by the advancing cell-formation. Nearer the centre we
find the cancer-cells in a state of retrogressive metamor-
phosis, producing a diminution in the size of the alveoli,
and leading to a puckering of the external surface of the
tumor. Fig. 238 exhibits each of these stages.

292

THE MICROSCOPIST.

Scirrhus is generally met with in the mammse and in
the alimentary canal. It is quite hard previous to pass-
ing into the ulcerative stage, and on section the tumor
exhibits a grayish-white glistening surface with occasion-
ally fibrous interlacing bands. Scraping the juice from
such a tumor may suffice for a cursory microscopic exami-
nation of its cells.

FIG. 233.

Carcinoma simplex mammae, a. Development of nests of cancer-cells. 6. Fully formed
carcinoma tissue, c. Commencing cicatrization ; at the same time a representation of
the relations of stroma and cells in scirrhus. d. Cancer cicatrix. 1-300. — After RIND-

FLEISCH.

(2.) Encephaloid. — Medullary or acute cancer differs from
scirrhus in the rapidity of its growth, and consequent
softness of its structure. It is generally so soft as to be
brainlike, hence the term encephaloid. There are, how-
ever, all intermediate stages of hardness in cancers be-
tween the extremes of scirrhus and encephaloid. In the
latter epithelial growth is very rapid, and the proportion
of stroma small, while the abundance and softness of the
bloodvessels produces frequent haemorrhages.

Encephaloid occurs generally in the internal organs as
a secondary growth after extirpation of a cancerous

THE MICROSCOPE IN PATHOLOGY.

293

tumor, although it may occur primarily also, as in the
articular ends of bones, in the eye, in the testicles, etc.

(3.) Colloid. — Alveolar or gelatinous cancer. This form
depends on the metamorphosis of one of the preceding
forms, the cells of which undergo a mucoid or colloid
change. It is exceedingly malignant, and may occur in
the stomach, large intestine, liver, ovary, or mammary
gland (Fig. 239).

Fir. 239.

Carcinoma gelatinosum. 1-300. — After RINDFLEISCH.

4. Epithelioma. — Cancroid, or epithelial cancer, always
grows in connection \vith a cutaneous or mucous surface,
and its epithelial elements resemble the squamous variety
of epithelium so as scarcely to be distinguished from the
normal cell. They sometimes have more than one nu-
cleus, and are often flattened and distorted by mutual
pressure. They are not so ready to undergo fatty degen-
eration as the cells of other varieties of carcinoma. As
the cells multiply they have a marked tendency to be ar-
ranged concentrically in groups, forming globular masses
— " epithelial pearls," "bird's-nest bodies," etc. (Fig. 240).

There is little doubt as to the epithelial origin of the

•294

THE MICROSCOPIST.

cells in epithelioma. It may be said of this structure, as
well perhaps of all varieties of carcinoma, that it is com-
posed of epithelium run mad, — epithelium become heterol-
ogous, — extending beyond its normal limits into subjacent
tissues. Epithelioma is first seen as a small foul ulcer
with indurated edges, or as an induration or nodule which

Section of a cylinder of epithelial cells, under a magnifying power of 500. a. The
cylinder itself, with the characteristic stratification of its cells, a younger and an older
pearly globule. 6. The stroma, very rich in cells at c, and contributing directly to the
enlargement by apposition of the cylinder. — After RINDFLEISCH.

subsequent^ ulcerates. The surface of the ulcer is often
villous, and the cut surface yields on pressure a small
quantity of turbid fluid, or a thick curdy material like
the sebaceous matter of the glands of the skin. This is
composed of epithelium. Epithelioma often occurs on
the lower lip at the junction of skin and mucous mem-
brane. It may also grow on the tongue, scrotum, etc.,
and by its development may involve any tissue whatever.
Wagner describes three varieties of epithelioma : the
papillary, or warty pavement-cell cancer, whose surface

THE MICROSCOPE IN DIAGNOSIS. 295

is similar to warts or pointed condylomata ; cicatricial,
occurring usually in the skin of the face of old people as
a superficial slowly growing cancer, presenting a cicatri-
cial contraction of the stroma from gradual retrogression
and reabsorption of the cells ; and the mucous cancroid,
or cylindroma, characterized by cylindrical or arborescent
masses of mucous substance.

The term cylindrical epithelioma has been given to those
forms which appear on mucous membranes with columnar
or cylindric epithelium. The tumors present the same
epithelial elements as the tissues whence they grow. The
walls of the alveoli show columnar epithelium, so that
the distinction between such tumors and simple adenom-
ata is very difficult. A variety of this form occurs as a
villous growth on mucous membranes, as the bladder,
uterus (cauliflower excrescence), and stomach.

CHAPTER XIV.

THE MICROSCOPE IN DIAGNOSIS.

IN diagnosis the microscopical observer is necessarily
confined to an examination of the various fluids and dis-
charges of the body. Dr. Pritchard's microscope for ex-
amining the circulation of blood in the frseiwm of the
human tongue, described by Dr. Beale, is an ingenious
attempt to investigate the actual condition of the living
subject, and indicates a direction which may hereafter be
profitably pursued, but as yet is too refined for the pur-
poses of the practical student.

I. THE BLOOD IN DISEASE.'

The normal structure of blood has been sufficiently de-
scribed at page 186. It remains now to point out briefly

296 THE MICROSCOPIST.

the methods of examination and considerations useful in
diagnosis.

The presence of too large a proportion of white corpus-
cles (leucocytes) in the blood constitutes what is known
as leucaemia, and is usually associated with morbid changes
in the spleen and lymphatic glands. But the relative
numbers of white and red corpuscles vary in different
persons, at different times, and in different morbid states,
so that great care is needed in forming an opinion. Thus
in anaemic and cancerous patients the proportion of white
corpuscles is increased.

Prick the skin of the finger with a needle after moderate
compression, and place the drop of blood thus obtained on
a perfectly clear slide, and cover with thin glass in the
usual way. No more blood should be taken than is suffi-
cient to fill the capillary space between the slide and cover.
The white corpuscles in the field of the microscope should
then be counted, or an estimate made of the proportion
of white to red corpuscles.

Several "fields" should be averaged before arriving at
an opinion. This is but a rough method, and for more
accurate determination a variety of tubes and slides have
been devised. The capillary apparatus of Dr. Malassez
is so constructed that one volume of blood diluted with
one hundred volumes of a ten per cent, solution of sul-
phate of soda, to facilitate enumeration and prevent co-
agulation, is placed in a capillary tube adjusted on a glass
slide so as to indicate a definite cubic capacity for a given
length, which relation is marked on the slide by the in-
strument-marker. Then, by means of an eye-piece mi-
crometer, divided into squares, the actual number of cor-
puscles, white and red, can be counted, and on multiplying
by one hundred for the dilution used, we have the figure
desired. Hayem and Nachet employ a slide having a
glass ring one-fifth of a millimeter in depth cemented on
it. A drop of blood diluted as above is placed in the cell

THE MICROSCOPE IN DIAGNOSIS. 297

and covered with a flat glass cover. As soon as the cor-
puscles have settled to the bottom, the number in a defi-
nite area is counted. If the area chosen is one-fifth of a
square millimeter, we have, of course, one-fifth of a cubic
millimeter of diluted blood ready for enumeration by aid
of the ocular micrometer divided into squares as before.

Changes in the appearance of the globules, white or
red, should be noted, even though such changes are due
to physical causes, as crenated margins, not running to-
gether in rouleaux, etc. Minute particles of bioplasm (mi-
crocy tes) are sometimes seen, appearing as granular debris,
whose significance is unknown. In pernicious anaemia
globular cells, deeper in color and smaller than ordinary
red globules, have been observed. In a case reported by
Dr. Mackenzie the number of red disks was but 18.6 per
cent, or 930,000 to the cubic millimeter, instead of 5,000-
000 (page 187).

In the disease known as malignant pustule, splenic
fever, anthrax, etc., a short, straight, motionless rod,
about as long as the width of a blood-corpuscle, has been
found in the blood, and is definitely related to the activity
of the virus. It is called Bacillus anthracis, and resembles
a common and harmless one found in infusions of hay,
etc., the Bacillus subtilis, although the latter is endowed
with motion.

In relapsing fever, during the paroxysm and relapse,
but not in the interval, Spirilla are found in the blood.
They are minute spirals of great tenuity, and are from
two to six times the breadth of a blood-corpuscle.

The Filaria sanguinis hominis is found in the blood and
urine of persons affected with a certain form of chyluria.
It is about the breadth of a blood-cell, and ^gth of an
inch in length. It exhibits active wriggling movements.*

* Finlayson's Clinical Diagnosis.

298 THE MICROSCOPIST.

Dr. Cobbold states that its larval state is passed in the
stomach of the mosquito.

Dr. Beale has found cells similar to white corpuscles,
but larger, in cases of cholera and of pyaemia. Many of
these were too large to pass the capillaries.

The tendency of cells to adhere is thought by Beale to
depend on a reduction of the amount of water. He ob-
served such tendency to be increased after watery evacua-
tions by Epsom salts.

Dr. Coupland described corpuscles, of a red color, ^^th
of an inch in diameter in blood from a case of Addison's
disease. They disappeared as the patient improved.

Dr. Lostorfer, of Vienna, professed to be able to distin-
guish syphilitic blood by the presence of peculiar bright
bodies in from one to five days after it had been taken
from the patient. The drop of blood on a slide, covered
with thin glass, is placed under a bell-glass arranged as a
moist chamber. In from one to five days, in addition to
vibriones, bacteria, and sometimes sarcina, there appeared
these bright bodies, some at rest and some vibratile.
Many of the larger ones were seen to increase by budding.
He calls them syphilitic corpuscles.

Epithelial elements from the lining of the bloodvessels
have been seen in the blood. Cancer-cells may in this
way be transferred to distant parts. Epithelial cells be-
coming impacted in the smaller vessels may give rise to
thrombosis and abscesses, as in puerperal and pysemic
fever.

Dr. Beale's researches upon the cattle-plague led him
to believe that particles of germinal matter (contagium)
introduced from without into diseased blood, and the
products of their decay, may give rise to local congestions
and various eruptions, as boil, carbuncle, and pustule.

Dr. Salisbury thinks that rheumatism may be detected
long before the appearance of active symptoms by the
excess of fibrin deposited in a drop of blood. He states

THE MICROSCOPE IN DIAGNOSIS. 299

that cholesterin or nerve-fat may be seen in blood which
has been kept from one to three days, and that variations
in this, seen under the microscope, may throw light upon
disordered mental and nervous functions. He claims that
carbuncle, intermittent fever, enteric fever, and small-pox
are produced by fungi in the blood, which he names re-
spectively Crypta carbunculata, Gemiasma viridis, Byoly-
sis typhoides, and Ivy variolosa.

The examination of blood in disease requires patient
care and the employment of high powers, not less than
1000 diameters. As a field for original investigation, this
subject affords a most tempting opportunity to those who
have the leisure and skill to pursue it. The time may
come when more may be known of a patient's disease by
an examination of a drop of blood under the microscope
than is possible in any other way.

In medico-legal inquiries the decision whether a blood-
stain is of human blood or of one of the lower animals is
one requiring exceptional skill, if, indeed, it is at all
practicable. The differences given on page 187 are easily
enough seen, but the red disks in a dog, a rabbit, etc., so
nearly approach those of human blood in size, and the
appearance of corpuscles in the same drop varies so much
under high powers, as to lead to doubtful testimony before
a jury. Dr. J. G. Richardson believes it quite possible to
distinguish human blood, but at present few microscopists
agree with him. In a doubtful case it would be well to
scrape off from the slide half of the drop of suspected
blood, replace it with undoubted human blood, and pho-
tograph the disks, so that one-half in the field of view
would be known and ready for comparison with the other
half.

To detect the red corpuscles in a blood-stain, it is well
to soften the clot with glycerin diluted with water to the
specific gravity of serum, or a one per cent, solution of
salt may be used. If this fails, an attempt may be made

300 THE MICROSCOPIST.

to obtain haemin crystals. A portion of the supposed
blood-clot is placed on the slide, and a drop of water con-
taining a trace of salt is added. A thin glass cover is
applied, and a little glacial acetic acid is allowed to flow
in and mix with the blood. Heat is applied until the
mixture almost boils. The slide is then placed under the
microscope, and the rhomboidal crystals may be observed
with a J-inch objective.

For microspectroscope appearances, etc., see page 102.
The guaiacum test, as it is called, depends upon the ozone
of the hsemaglobulin of the blood causing a bluish tint
in the solution of guaiacum. The tincture is made by
dissolving one part of the resin in six parts of alcohol of
eighty per cent. The bottles are to be only half filled, so
that the tincture may be in contact with the air. Strips
of white blotting-paper are soaked in this and the alcohol
allowed to evaporate. A weak solution of blood dropped
on the paper produces a blue color. This is only valuable
as a negative test, since other substances give the same
reaction. If no color is obtained, blood is not present.

II. EXAMINATION OF URINE.

Healthy urine contains a variety of organic and inor-
ganic substances, as urea, uric acid, alkaline and earthy
salts, animal extractive, vesical mucus, and epithelial
debris. A drop or two evaporated on a glass slide will
show the crystalline matters, consisting of urea, urate of
soda, chloride of sodium, phosphates, and sulphates.

Before examining urine for the purpose of diagnosis, it
is necessary to be familiar with the appearance of the
contents of healthy urine, as well as of accidental sub-
stances which are likely to be met with, as fragments of
hair, wool, feathers, cotton, silk, and flax, particles of
starch, breadcrumbs, sand, vegetable fibres, etc. Igno-

THE MICROSCOPE IN DIAGNOSIS. 301

ranee of the microscopic appearance of these common
things has led to ludicrous mistakes.

The amount of urine passed in each twenty-four hours
varies from 20 to 50 ounces, holding in solution from 600
to 700 grains of solid matter. The amount, both of solids
and fluids, varies according to the amount of fluids im-
bibed, the action of the skin, etc. The quantity of urine
should be considered in relation with its specific gravity,
since diminished urine with greater specific gravity may
occur in diarrhoea, etc., and imbibed fluids may cause
greater quantities with lessened specific gravity.

The average specific gravity of healthy urine is 1.020.
It may be measured by means of the specific gravity bot-
tle, or with the urinometer, a loaded glass bulb with
graduated stem. According to Dr. G. Bird, each degree
of the urinometer represents 2.33 grains of solids in 1000.
Thus specific gravity 1.020 represents 46.60 grains solid
matter, and 953.40 water in 1000 of urine.

Another table of Dr. Bird's shows that the specific
gravity figures indicate nearly the amount of solids in
each fluid ounce. Thus 1010 shows 10 grains of solids,
1020 about 20 grains, etc. Yet this is only approximate.

High specific gravities (above 1025) are found in dia-
betes (from sugar), in concentrated urine from fevers or
other causes, in acute renal dropsy, and sometimes from
large quantities of albumen in solution. Low specific
gravities (below 1015) occur when the quantity is exces-
sive, especially in diabetes insipidus,in lardaceous disease
of the kidney, and chronic cases of Bright's disease.

UREA.

Urea is the vehicle by which nearly all the nitrogen of
the exhausted tissues is removed from the system, and
its retention is often attended with fatal ursemic poison-
ing of the blood. The quantity naturally eliminated de-

302 THE MICROSCOPIST.

pends largely upon the amount taken in as food, but may
be stated generally as from 400 to 500 grains a day, or
3J grains per pound weight of the body. The specific
gravity of the urine usually gives an indication of the
quantity of urea excreted, since it is about one-third of
the amount of solid matter.

If urea be suspected in excess, a drop of urine (concen-
trated and cold) may be put on a slide and a drop of nitric
acid added. On covering with thin glass and placing
under J-inch objective, the characteristic rhomboidal crys-
tals of nitrate of urea will be seen (Plate XXVI, Fig.
240).

Volumetric analysis is the best means of ascertaining
the quantity of urea as of other chemical ingredients, but
this falls rather within the province of the professional
chemist than of the microscopist. The practitioner may
estimate approximately by weighing the crystals of nitrate
of urea formed by adding nitric acid to double the quan-
tity of urine \vhich has been concentrated to half its bulk.

CHLORIDES.

The chlorides are always present in normal urine. They
are diminished, and sometimes nearly suppressed, in sev-
eral febrile diseases, especially in pneumonia. The quan-
tity may be roughly estimated by acidulating the urine
with a few drops of nitric acid, and then adding a strong
solution of nitrate of silver. The density or abundance
of the precipitate, as compared with a sample of normal
urine, indicates the quantity; or the precipitate maybe
weighed after being dried and fused in a porcelain capsule.
Albumen, if present, must be separated before testing for
chlorides, as it is also thrown down by nitrate of silver.

PLATE XXVI.

FIG. 240.

£._/

CVyX^-00

Qj\ O £7/s,

I'A ^g/ (.J

Q
Nitrate of Urea.

FIG. 242.

V

Urate of Ammonia.

FIG. 244.

Uric Acid.

FIG. 241.

Tube-casts.

FIG. 243.

Uric Acid.

FIG. 245.

Uric Acid— re-precipitated.

THE MICROSCOPE IN DIAGNOSIS. 303

BILE.

Bile in urine, if present in large quantity, can be recog-
nized by the eye. In testing for albumen by nitric acid,
the greenish color produced by bile will also attract notice.
A more delicate test consists in placing a drop or two of
urine and a drop or two of strong nitric acid near together
on a white plate and allowing one to run into the other.
As the acid mixes with the fluid, a play of colors, com-
mencing in* green and terminating in red, passing through
various shades, will be observed.

Bile in urine indicates jaundice, and may aid in the
differential diagnosis of discolorations of the skin and
conjunctiva due to other causes. It may show an incipi-
ent jaundice before the tissues are generally affected, and
its disappearance may afford evidence that the attack is
passing off when the effects of jaundice may be visible
elsewhere.

ALBUMEN.

In suspected albuminuria, samples should be examined
which were passed at different times of the day, as before
eating in the morning, and after eating in the evening.
Care should be taken to have clean bottles, test-tubes, etc.
The urine should be subjected to a double test, by boiling
in a test-tube and the subsequent addition of a drop or
two of nitric acid, and by the addition of strong nitric
acid to a separate portion of the cold urine. In the latter
test a cloudy ring of albumen appears at the junction of
the two fluids.

The quantity of albumen may be estimated sufficiently
for clinical practice by allowing the precipitate formed on
boiling to subside for a definite time, — twelve to twenty-
four hours, — and observing how much of the tube is occu-
pied, as a half, a fourth, an eighth, etc.

304 THE MICROSCOPIST.

Sometimes albumen is due to the presence of blood, pus,
etc., as revealed by the microscope, and its significance
must be considered under these terms. Many acute febrile
diseases give rise to albuminuria, which may be regarded
as one feature of the general disturbance rather than of
local importance.

After the primary fever of scarlatina, and occasionally
after small-pox, enteric fever, and erysipelas, albuminuria
is present. It is not infrequent in pregnancy and the
puerperal state, and though not necessarily, yet often in-
dicates possible danger of convulsions during labor, chronic
renal disease, etc.

Chronic chest complaints are often complicated with
albuminuria, which has an important bearing on progno-
sis. In such cases it may be only one of the indications
of a temporary general venous congestion, or it may indi-
cate a nephritis established through long-continued con-
gestion, or the renal disease shown by the albuminuria
may be primary and the thoracic affection a complication.
In all dropsies the presence of albumen is important.
Genuine renal dropsy rarely occurs without it, yet it may
be secondary and due to pressure on the renal veins

Albuminuria in acute or chronic renal disease must be
considered in connection with other urinary contents, as
tube-casts, epithelium, etc., and with alterations in quan-
tity, specific gravity, etc.

The significance of albuminuria in nervous diseases is
variable. It may be an effect of nervous disturbance, as
after a convulsion or from some lesion of the brain, or the
renal disease may be the cause of the nervous affection,
as in urcemic coma or convulsions, etc.

We must look for albumen in the urine in many chronic
and constitutional affections, and transiently after the use
of blisters, etc. Where there are so many sources of
albuminous urine we must be guided by the general
symptoms, and particularly the presence of microscopic

THE MICROSCOPE IN DIAGNOSIS. 305

deposits, derangements of quantity, and density in the
urine.

SUGAR.

Urine should be tested for sugar when diabetes is sus-
pected, or when the quantity is excessive, or the specific
gravity is high (above 1030). In some cases of cerebral
disease, also, sugar appears in the urine. The urine should
first be examined for albumen, since its presence is a serious
complication of diabetes, and it may interfere with the
reactions by the copper test. If present it should be re-
moved by boiling and filtration. Boiling albuminous urine
with crystals of sulphate of soda is said to render it suit-
able for the copper test, but the other way is best.

Copper Test — Trommer's Test. — The urine is mixed with
a few drops of a solution of sulphate of copper in a test-
tube; excess of liquor potassee is then carefully added,
enough to just dissolve the precipitate it first throws
down ; the mixture is then boiled, and if sugar is present
a red precipitate of suboxide falls down. As errors occur
from not using the proper proportions, the following test
is preferred:

Fehling's Test Solution.— Sulphate of copper, 90 J grains ;
neutral tartrate of potash, 3tf4 grains; solution of caustic
soda (of specific gravity 1.12), 4 fluid ounces; add water
to make up 6 fluid ounces. (Or 40 grams of sulphate of
copper in crystals, 160 grams neutral tartrate or potash,
750 grams caustic soda, specific gravity 1.12; add water
up to 1154.5 cubic centimeters. Each 10 cubic centimeters
correspond to 0.05 gram of grape-sugar.)

A little of the test fluid is first boiled in a test-tube to
see if it remains unchanged in color, since it is apt to alter
by age. If unaffected, add a drop or two of the suspected
urine. If sugar be present in quantity the color changes,
and a yellowish or reddish precipitate falls. If no reac-
tion occurs, add a little more urine, but less than the

20

306 THE MICROSCOPIST.

volume of test fluid, boil it and cool; if no yellow or red
suboxide falls, it is free from sugar. Prolonged boiling
must be avoided, as well as boiling the urine before add-
ing the test.

To determine the quantity of sugar by the copper test
Fehling's solution is made of such strength that 200 grains
(by measure) are completely reduced by one grain of dia-
betic sugar. The test fluid is boiled in a flask, etc., and
a quantity of pure water equal to one or two volumes of
test fluid poured in also. The saccharine urine, diluted
with one volume urine to nine of water if suffar is abun-

Z3

dant, is placed iu a burette, graduated to grains, and is
gradually added to the boiling copper solution till the
blue color is quite discharged. The number of grains of
urine consumed — representing one grain of sugar — is
read off, and it is then a matter of calculation how many
grains are contained in the ounce of urine, making allow-
ance for the degree of dilution.

fermentation Test. — This is sometimes more convenient
or preferred from uncertain results of the copper test. A
small tube is filled with suspected urine, a little fluid or
solid (German) yeast is added, and the tube is inverted
over a saucer containing urine and placed in a warm situ-
ation for twenty -four hours. If sugar is present it under-
goes fermentation, yielding alcohol and carbonic acid.
The latter rises in the tube and displaces the liquid. The
quantitative test by fermentation consists in determining
the specific gravity of the urine before and after complete
fermentation. It has been found, empirically, that one
degree of specific gravity lost by fermentation corre-
sponds with one grain of sugar per fluid ounce of urine.

Bismuth Test. — Mix an equal volume of suspected urine
with a solution of carbonate of soda — one part of the
crystals to three parts water (or with half as much liquor
potassae). Put in a little basic nitrate, or subnitrate of
bismuth, and boil. If sugar be present the bismuth be-

THE MICROSCOPE IN DIAGNOSIS. 307

comes grayish or blackish from the formation of the sub-
oxide or of metallic bismuth.

URINARY DEPOSITS.

Deposits from urine are either organic or precipitates
from solution. The urine should be put in a conical glass
of four or five ounces capacity, and kept free from dust
for about twelve hours. A small portion of the sediment
should then be taken up with a clean pipette and ex-
amined under the microscope on a glass slide covered in
the usual way (page 77). A quarter of an inch objective
will be found most generally useful.

To facilitate microscopical examination and diagnosis
we add the following table from Richardson's Medical
Microscopy :

I. A distinct deposit is seen in the urine.

A. This deposit is light and flocculent.

a. It occurs in albuminous urine, one yielding a coagu-
lum with heat, and nitric acid.

a. The microscope shows casts of the uriniferous tubules
(transparent or granular cylinders ^-g-th to ^-^ih of an
inch in diameter), either granular, epithelial, or hyaline, —
Bright' 's disease of the kidney.

p. The microscope shows red blood-corpuscles (non-nu-
cleated disks 35V<jth of an inch in diameter), mixed with
mucus, — hcematuria.

y. Leucocytes only are seen (nucleated corpuscles, — pus-
corpuscles, — jjsg-Q-th of an inch in diameter), — nephritis,
cystitis, etc.

b. The urine is not albuminous.

a. Leucocytes, epithelial cells from the bladder, and per-
haps mucous casts of the tubules appear, — irritation of
urinary tract.

P. Spermatozoa, — if numerous, spermatorrhoea,
Y- Fungous growths (cellular bodies ^Vo^1 to

308 THE MICROSCOriST.

of an inch in diameter, often arranged in chains, still, or
vibratile), — pathological significance uncertain.

d. Hyaline and pale tube-casts (rare in non-albuminous
urine), — Bright9 s disease.

B. Deposit dense, opaque, bulky.
a. Urine non-albuminous.

a. Microscopic deposit, granular simply, — urates or phos-
phate of lime. The former dissolve on heating.

ft. Microscopic crystals, triangular prisms and their de-
rivatives,— triple phosphates.

b. Urine albuminous.

«. Leucocytes only, — nephritis, cystitis, etc.
ft. Crystals of triple phosphates, with leucocytes, —
chronic cystitis, perhaps calculus.

C. Deposit granular or crystalline; small.
a. Urine albuminous.

a. Red blood-disks, — h&maiuria.

ft. Cancer-cells (irregular, caudate, and oval, with large
nuclei), — carcinoma. Mistake not epithelial for cancer
cells.

f. Tubercle corpuscles (non-nucleated, granular, oval
bodies, about j^^thof an inch in diameter), — tuberculosis.

b. Urine not albuminous.

a. Oxalate of lime crystals (brilliant octohedra, show-
ing as squares marked with diagonal crosses, or more
rarely as dumb-bells), — oxaluria.

ft. Uric acid crystals (yellowish, lozenge-shaped, oval,
barrel-shaped , e tc . ) , — lithuria .

Y Microscopic spherules and dumb-bells, soluble in
acetic acid with effervescence, — carbonate of lime.

S Hexagonal crystals of cystin, — cystinuria.

e. Sediment resembling uric acid, but soluble in hot
water and mineral acids, — xanthin.

C. Sheaflike bundles or globular masses of acicular crys-
tals, tyrosin and leucin, — acute atrophy of liver?
f). Hydatids, etc., — entozoa.

THE MICROSCOPE IN DIAGNOSIS. 309

II. Urine turbid, without distinct deposit.

A. Turbidity disappears on warming, — amorphous
urates.

B. Cloudiness remains while heating.

«. Yibriones and bacteria present, — putrefactive fermen-
tation.

p. Numerous minute molecules, — chylous urine.

III. A film on surface of urine.

A. Prisms of triple phosphates, usually with granular
phosphates and spherules of urate of soda, — phosphuria.

B. Numerous small oil-globules, with triple phosphates,
— kiestin.

EPITHELIUM.

The character of the epithelial scales will often show
the locality of disease in the urinary tract (Fig. 142).
JRenal epithelium, lying loose in the deposit is somewhat
globular, and may sometimes be compared with that in
the tube-casts in the same specimen It bears quite a re-
semblance to pus-cells. It occurs in desquamative nephri-
tis, and undergoes various changes, appearing atrophied,
granular, or fatty. Sometimes large granular corpuscles
occur with fatty epithelium, being altered cells them-
selves.

Cells from the bladder occur often as groups of tessellated
cells of circular form — sometimes pyramidal. Caudate
epithelium is found in the ureter and pelvis of the kidney,
and may be caused by calculous pyelitis. Large scaly
epithelium comes from the vagina.

MUCUS AND PUS.

Mucus is deposited as a flocculent cloud, entangling a
few round or oval delicately granular cells, a little larger
than a red blood-globule. In disease this increases and
contains numerous ill-defined cells. A very thick glairy

310 THE MICROSCOPIST.

deposit in disease of the bladder may be mistaken for
mucus when it is pus altered by the action of carbonate of
ammonia.

Pus is formed often from the germinal matter of epi-
thelium, so that a small quantity in urine is not neces-
sarily a sign of serious disease. In large quantities pus
forms an opaque cream-colored deposit, which becomes
glairy and tenacious by the addition of liquor potassae.
The addition of the latter will dissolve white urates, and
serves to distinguish pus from them as well as from phos-
phates, which are little affected by it. The microscope,
however, is the best test.

Purulent urine is usually acid if of renal origin (if tested
immediately), and is alkaline and ammoniacal in suppura-
tion from the bladder. Coexisting epithelium, etc., is
often of value in determining the origin of pus. Pus-
globules under the microscope, if long removed from the
body, are granular and show from one to four nuclei when
treated with acetic acid. In fresh pus-corpuscles, espe-
cially in warm weather, amoeboid motion is often seen.
In a late period of catarrh of the bladder but little epi-
thelium may accompany the discharge, but crystals of
triple phosphates occur generally in pus derived from the
bladder.

The clinical significance of pus in the urine is quite
varied. It may follow renal inflammation, and often ap-
pears in alburninuria following fevers and in renal em-
bolism. Abscesses opening into the urinary tract, cysti-
tis, cancer of the bladder, suppuration of the prostate,
gonorrhoea, and gleet may all give rise to purulent urine.
Accidental mixture from lochial or leucorrhoeal discharges
is also possible.

BLOOD.

Blood may sometimes be recognized by the eye in urine
from its smoky or dingy tint, especially in blood from the

THE MICROSCOPE IN DIAGNOSIS. 311

kidney. ' Blood-disks usually form a reddish-brown de-
posit. The microscope will generally exhibit the disks,
unless they are greatly disintegrated, when we must be
guided by the quantity of albumen and other tests.
Blood in urine may proceed from some general disease af-
fecting the bloodvessels generally, or from some poisonous
agent acting on the kidneys, as cantharides, turpentine,
creasote, and alcohol, or from some local affection of the
urinary organs and passages. Of course the general symp-
toms of the patient must be considered, but sometimes
the kind of epithelium present may be a guide to the
source of the haemorrhage.

SPERMATOZOA.

Spermatozoa, resembling tadpoles with elongated tails,
are not uncommon in perfect health, but nervous patients
are often deluded by quacks on account of them. Of
course, when present habitually and in large numbers
they may afford evidence of spermatorrhoea.

Bacteria and vibriones often appear in alkaline and
decaying urine. The sugar fungus (Torula), or yeast plant,
is developed when there are even minute traces of sugar.
Other fungi with branching growths are also frequent.
Some of these may resemble tube-casts. Spores of globular
shape may be mistaken for blood-corpuscles. Sarcime, or
minute cubic organisms, dividing into groups of four and
its multiples, are sometimes found in the urine of dyspep-
sia.

TUBE-CASTS.

In many cases of congestion and inflammation a coagu-
lable material is effused into the tubes of the kidney,
forming a cast or mould of the tube. This may be ejected,
bringing with it pus, blood, epithelium, or other material

312 THE MICROSCOPIST.

with which it is associated. In Bright 's disease these
casts, in addition to albuminous urine, assume consider-
able clinical importance. In the acute form of the disease
the cylinders or casts are fibrinous, with blood, mucus,
or pus cells, and epithelium. Towards the close the casts
become homogeneous or hyaline. In chronic desquama-
tive nephritis the cylinders are without blood, arid to-
wards the end waxy or fatty, often containing many oil-
globules (Plate XXVI, Fig. 241). The specimen of urine
examined for casts should have settled for several hours, and
the drop of sediment examined should be carefully focussed
and illuminated. The casts are of various sizes, those of
very large diameter indicating dilation of the renal tubules.
In bloody or purulent urine tube-casts point out a renal
element in the case. They do not always indicate Bright's
disease, as they may be associated with the irritation of
a calculus, and are sometimes found in jaundice without
serious renal trouble or albuminuria.

CRYSTALLINE AND AMORPHOUS DEPOSITS.

Uric Add. — Crystals of uric acid may often be recog-
nized as a red sand, lying at the bottom or on the sides
of the vessel, or entangled in mucus. They may be yel-
low, red, or brown, from coloration by urinary pigment.
Their microscopic forms are various, but are usually some
modification of the rhomb. Thus they may be rhomboid
tablets with obtuse angles, or the shape of a whetstone
(Plate XXVI, Fig. 242). When slowly precipitated, uric
acid may form druses of four-sided prisms (Plate XXVI,
Fig. 243). When precipitated from fresh urine by the
addition of muriatic acid, the crystals are large and often
of various shapes. They may be tested by dissolving in
potassa and reprecipitating by muriatic acid, when they
assume the shape of Fig. 244, Plate XXVI. Crystals of
uric acid may occur as a film as well as a deposit. They
originate from tissue-waste, excess of nitrogenous food,

THE MICROSCOPE IN DIAGNOSIS. 313

defective assimilation, congestion of the kidney, or chronic
disease of the respiratory organs.

Unties or lithates are salts of uric acid combined with
soda, potash, or ammonia, the exact composition being
difficult to determine. Such sediments are very common.
They are generally amorphous, but sometimes crystalline
(Plate XXVI, Fig. 245). The urate of soda presents the
form of globules with projecting spiculse. The color is
various, from a light pink to brickdust color. It is de-
posited in all concentrated urine, and is often a "critical
discharge " in fevers, etc. It is found in gouty concretions,
and dissolves with heat and acids.

Phosphates appear in two forms, crystalline and amor-
phous. The crystalline are the crystallized phosphate of
lime, and the ammonio-magnesian (or " triple") phosphate.
The latter is most common, and may appear in any de-
composing urine. It may be precipitated from fresh urine
in stellate crystals (Plate XXVII, Fig. 246) by adding
ammonia. More slowly deposited from alkaline urine, or
in disease, the crystals are prismatic, generally triangular,
with truncated ends. Sometimes the truncated ends are
bevelled, and the various lengths of the prisms give rise
to a variety of forms (Plate XXVII, Fig. 247).

Triple phosphates are generally thought to proceed
from disintegrated albuminous, and chiefly nervous mat-
ter, but their clinica limportance is riot fully settled.
They are found in cases of nervous depression, various
forms of dyspepsia, shock of the spinal cord, irritation of
the bladder, etc.

In highly alkaline urine the triple phosphates are often
accompanied with pus and phosphate of lime. The latter
occurs as minute granules or dumb-bells, or in groups of
crystals (Plate XXVII, Fig. 248). They are dissolved by
acetic acid, which distinguishes them from uric acid.

Oxalate of lime is deposited in small octohedra, gener-
ally appearing under the microscope as minute squares
with crossed lines proceeding from the angles, the upper

314 THE MICROSCOPIST.

angle being next the eye (Plate XXVII, Fig. 249).
Dumb-bell forms and circular 'or oval crystalline masses
are sometimes seen.

Oxalate of lime is found as a urinary deposit in various
conditions, as in pulmonary and dyspeptic affections. It
is usually associated with hypochondriasis, and in cases
of overfatigue, particularly from mental work, it is com-
mon. The train of nervous and dyspeptic symptoms with
which it is associated have been supposed to indicate an
"oxalic acid diathesis," and have been named "oxaluria."
Its association with calculi renders it interesting to the
surgeon.

Chloride of sodium never crystallizes from fluid urine.
On evaporation it occurs in stellar form or in cubes (Plate
XXVII, Fig. 250). The presence of urea sometimes dis-
poses it to assume the form of a regular octahedron. The
amount of this excretion in typhoid fever and in inflam-
mations of the respiratory organs is greatly diminished.
It is absent in commencing hepatization of the lung, but
returns on resolution of the inflammation (see Chlorides,
page 302).

Cystin crystallizes in characteristic six-sided plates
(Plate XXVII, Fig. 251). It contains twenty-six per
cent, of sulphur, and is considered a product of decompo-
sition. It is often associated with calculus. Some regard
it as indicating a strurnous and ill-nourished system.

Carbonate of lime occurs rarely in human urine, but is
common in that of the horse. Its form is that of a
spherule made up of acicular crystals. It effervesces in
acetic acid.

Tyrosin, in sheaflike or globular masses, sometimes
occurs in typhus and in atrophy of the liver.

III. PUS AND MUCUS IN DIAGNOSIS.

"We have already considered the bioplasts of pus and
mucus as identical in character with other leucocytes, as

PLATE XXVII.

FIG. 246.

Ammonio-phosphjvte of Magnesia.

Ammonio-phosphate of Magnesia.

FIG. 248.

&^=> w^x —

* ^-fe *f7

. «U$^ jr^A

Phosphate of Lime.

FIG. 250.

%s£

1

FIG. 249.

J?

CO c?

Chloride of Sodium.

Oxalate of Lime.

FIG. 251.

I oO

/^\ rsjCfcl

Cystine.

FIG. 252.

Salivary corpuscles, epithelial scales and granules.

THE MICROSCOPE IN DIAGNOSIS. 315

the white blood-cells (see pages 189 and 309). They
are easity seen by the microscope in a drop of purulent
matter placed on a slide and covered by thin glass. Pus-
corpuscles shrink in size on being placed in liquid of
greater specific gravity than serum, and are destroyed by
the action of caustic alkalies so as to be changed into a
tenacious glairy mass. Dilute acetic acid causes them to
swell and become transparent, exhibiting from one to four
nuclei. Bacteria and their germs (microzyrnes) are often
seen with pus, and indicate commencing decomposition.

According to Dr. Beale, the figures and descriptions
generally given of pus represent dead, not living pus. He
recommends a little pus to be taken from suppurating
skin or mucous membrane and examined at once, in order
to see the projections from the bioplasts, by the detach-
ment of which they multiply. He considers the " mucous
corpuscle" to be nothing more than an imperfect epithe-
lial cell surrounded by the viscid mucus formed by it.
This may grow rapidly, and the resulting particles become
true pus-corpuscles.

Richardson regards the difference between pus and
mucus to be that "the liquor muci is a secretion, which,
having been acted upon by the germinal matter of the
epithelial cells covering the basement mucous membrane,
is not albuminous, while the liquor puris is an exudation,
which contains albumen, that may be recognized by ap-
propriate tests."

IV. EXAMINATION OF MILK.

Examination of human milk may sometimes aid in
diagnosis, as in contusions of the breast, incipient mastitis,
and in the diarrhoea and innutrition of infants. The origin
of milk may be elucidated by the remarks on lactification
on page 233.

A thin stratum of milk should be examined with a
power of from 200 to 400 diameters, and an estimate

316 THE MICROSCOPIST.

made of the milk-globules, as in the ease of the blood-
corpuscles (page 296); or the sample may be compared
with a specimen known to be healthy.

Impoverished milk is known by the small number and
size of the globules. Colostrum or " exudation " corpus-
cles are numerous shortly after childbirth. In engorge-
ment of the breast the globules aggregate in masses, and
sometimes from inflammation, blows, etc., blood and pus
may be found. Starchy adulteration may be detected by
the addition of iodine. Richardson speaks of fibrinous
casts of the lacteal ducts occurring after puerperal masti-
tis, and Beale of minute particles of contagious bioplasm
in the milk of a cow suffering from cattle-plague, and
considers it possible that typhoid fever, etc., may be thus
propagated.

Y. SALIVA AND SPUTUM.

Besides the epithelium of the mouth, saliva holds in
suspension certain oval or spherical bodies, probably de-
rived from the glandular follicles, called " salivary cor-
puscles " (page 189).

Dr. Richardson considers them identical with leuco-
cytes. Beale supposes them to be concerned with the con-
version of starch into sugar, which occurs from the action
of the saliva. The peculiar dancing movement of the
granules of these corpuscles needs a y^th of an inch object-
glass, or one even higher, to see them well.

In examining sputum a small piece should be placed on
a slide and teased out with needles, if necessary, in glyc-
erin and water, or some indifferent fluid. We may ex-
pect to find mucus entangling air-bubbles and pavement
epithelium from the mouth (Plate XXVII, Fig. 252). The
observer should, however, be familiar with the appear-
ance of fragments of food, starch, epithelium from the
various parts of the air-passages, fungi, etc.

In catarrhal affections ciliated epithelium from the

THE MICROSCOPE IN DIAGNOSIS. 317

nasal or respiratory passages may be seen, and perhaps
molecules of fat, pus-globules, blood, and " inflammatory
corpuscles." In phthisis the decaying lung may be early
detected by the fibres of elastic tissue from the walls of the
pulmonary vesicles. The sputa should be first liquefied
by boiling a little while in an equal bulk of caustic soda,
then allowed to settle in a conical glass, when a small
quantity may be removed to a glass slide, covered with
thin glass, and placed under the microscope.

The occurrence of fungi in sputum is to be expected
whenever there is decay. The Leptothrix buccalis, one
form of penicillium, is common on old epithelial scales of
the mouth, and in the latter stages of phthisis the sputa
will often show fungi in various forms of development.

In catarrhal pneumonia we may find fibrinous casts of
the alveoli of the lungs and epithelial elements, chloride
of sodium, etc. Hydatids are sometimes expectorated in
sputum, the appearance of the booklets of the echinococci
being quite characteristic. Scales of cholesterin and
blood-crystals may also occur, as well as calcareous con-
cretions and dark melanotic masses.

Richardson states that associated matters may indicate
the source of blood in sputum. Thus associated salivary
corpuscles might show haemorrhage within the mouth,
amoeboid leucocytes, haemorrhage in the fauces or trachea,
starch -granules and particles of food, hsematemesis, and
coagulated casts, pulmonary hsemorrhage.

VI. VOMITED MATTERS.

Microscopic examination of vomited matters reveals
muscular fibres, starch-granules, oil-globules, and shreds
of vegetable tissue, according to the diet of the patient.
Crystals of margarin, etc., are often seen. Blood, pus,
etc., may be recognized if their structure be not destroyed
by the digestive fluids.

Isolated specimens should be picked out with forceps

318 THE MICROSCOPIST.

and scissors, or the vomit should stand some time in a
conical glass and a little of the deposit removed with a
pipette.

Torula and other forms of fungi are often seen in vom-
ited matters. The vomit containing the sarcina ventrlculi
generally ferments like yeast.

The color of the " coffee grounds vomit" is due to dark-
brown pigment, probably the altered coloring matter of
blood.

Some specimens of cholera vomit showed numerous
flocculi, consisting of epithelium. The clear fluid of py-
rosis contains only a little epithelium and a few small oil-
globules. The green vomit depending on bile contains
cylindrical epithelium from the gall-ducts, scaly epithe-
lium, flakes and masses of biliary coloring matter, and fat-
globules.

Dr. Beale records a case of the detachment of flakes of
stomach epithelium in a case of scarlet fever.

Biliary matters, as cholesterin, etc., and even small gall-
stones, have been rejected by vomiting.

VII. INTESTINAL DISCHARGES,

Microscopists are not unfrequently called upon to ex-
amine dubious matters passed from the bowels. Dr. Ben-
net describes one case of yellowish pulpy masses passed
with the stools as consisting of undigested potato skins,
and another made up of a network of confervoid growths
developed in the intestinal canal. In one case, seen by
the author, tormina, etc., were produced by skins of grapes ;
another case exhibited the skin or testa of a large seed,
as the tamarind. These instances show the necessity of
the observer being familiar with various botanical and
histological appearances.

Blood-globules in feeces retain their natural appearance
in inverse proportion to the distance of the hsemorrhagic
point from the anus, so that quite fresh blood will indicate

THE MICROSCOPE IN DIAGNOSIS. 319

hsemorrhoids, fistula, etc., while more disintegrated disks
indicate effusion further up the intestinal tube.

Mucous casts or coagula of albuminous matters are not
very uncommon, either in flakes or tubular casts. The
mucus entangles epithelial cells, usually from the large
intestine. In typhoid fever crystals of triple phosphates,
altered blood, bacteria, and various fungi may be found
in the faeces, and the stools of cholera patients contain
large quantities of cylindrical epithelium, so that the
white flocculi are almost entirely composed of it.

Elastic fibres, exhibiting transverse striae like those of
the ligamentum nuchse of the giraffe, are sometimes found
arising, in all probability, from incipient decomposition
of ingesta.

Larvae of insects may sometimes be passed alive from
the bowels, as well as be ejected from the stomach. The
various forms of intestinal worms in their various stages
of development may also be met with. In some instances
the microscope is needed to distinguish between suspected
worms, or portions of worms, and accidental products.
Fatty matter in the stools, sometimes semisolid, is usually
attributed to derangement of the pancreas.

VIII. VAGINAL DISCHARGES.

The diagnostic value of discharges from the vagina,
either uterine or vaginal in their origin, has been yet but
little studied, and presents a field of special interest in
gynaecology. The discharge should be examined while
fresh and without the addition of water or other fluids if
possible. Should fluid menstrua be really necessary, in-
different fluids only should be used.

The menstrual discharge will be likely to contain young
and old epithelial scales and blood-globules. In dysrnenor-
rhoea considerable patches of the epithelial membrane
desquamate, and even entire casts of the uterus or vagina

320 THE MICROSCOPIST.

have been separated. The diagnosis between dysmenor-
rhoea and abortion may be determined by a microscopic
examination of such fragments, since the villi of the
chorion can be thus recognized if present.

In leucorrhoea old epithelial cells, loaded with fat, will
be seen, with imperfectly formed epithelium and pus
globules. Beale states that the development of pus-cor-
puscles from the bioplasts of epithelium may be success-
fully studied in leucorrhceal discharges. Sometimes blood-
globules will be seen altered by exosmosis, etc.

The white gelatinous discharge from the os uteri, often
seen in uterine catarrh, consists of mucus with epithelial
elements.

Fibrous, epithelial, and cancerous tumors or ulcers may
sometimes be recognized by their microscopic elements,
yet it must be remembered that altered epithelium may
be readily mistaken for the elements of cancer, etc.

The Trichomonas vaginalis (Donne) is common in the
yellow acrid mucus of vaginal blennorrhoea. It is a round-
ish ciliated animalcule, and may be distinguished from
ciliated epithelium by the elongation of the anterior end,
which is sometimes drawn out into a long filament or
flagellum.

The epithelium from the Fallopian tubes and uterus is
columnar and ciliated, while that of the vagina is squa-
mous, with large cells.

Accidental products may also be discharged from the
vagina, as well as from other cavities. In one case I found
a number of living Crustacea (Gammara-pulex}, which oc-
casioned great pruritus, but were dislodged by injections
of sweet oil.

Dr. Sims has shown how the microscope may aid in the
cure of sterility, since the uterine cervical mucus needs to
be slightly alkaline. If habitually acid it destroys the
spermatozoa.

THE MICROSCOPE IN ETIOLOGY. 321

CHAPTER XV.

THE MICROSCOPE IN ETIOLOGY.

THE study of aetiology, or the knowledge of the causes
of disease, although so important a branch of practical
medicine, needs the careful and united efforts of many
observers to be classified and recorded before approaching
perfection. Here, also, the microscope will be found an
important aid. The numerous external causes of disease,
such as physical or organic impurities in the atmosphere,
soil, water, and food, vegetable or animal parasites, and
"disease germs," with their relation to epidemic or en-
demic disorders, all require skilful use of the microscope.

I. EXAMINATION OF THE AIR.

The pressure, temperature, moisture, and electricity of
the air, all of which are important in considering causes
of disease, require other modes of investigation, but the
microscope maybe reasonably expected to aid in inquiries
concerning mechanical, chemical, o'r organic impurities.

Many methods have been proposed for collecting mat-
ters suspended in the atmosphere. A shallow dish con-
taining distilled water, or a clean glass vessel containing
ice, so as to condense the atmospheric moisture with its
impurities on the outside, and allow7 it to trickle into a
conical receiver, have been used. Glass plates moistened
with glycerin and exposed to the air are still better. The
aeroscope of Dr. Maddox is a funnel-shaped tube turned
to the wind by a vane. The narrow end of the tube is
opposite a slide moistened with glycerin.

Many absurd " discoveries " have been paraded respect-
ing matters in air and water, yet careful observation will

21

322 THE MICROSCOPIST.

reveal valuable facts. Solid fragments of carbon or silex,
etc.. starch grains, filaments of cotton, flax, wool, silk,
etc., spores of fungi, animal and vegetable debris, etc., all
require considerable familiarity with microscopic objects
in general, without which no one should undertake such
investigations.

Minute living particles of bioplasm, either ordinary pus
or what Dr. Beale calls "disease germs," should be dili-
gently sought for under high objectives.

Pollen-grains are often found in the air. In Schuylkill
County, Pa., in the summer of 1858, after a rain-shower,
a yellow scum of pollen covered all the pools, and was
traced over a tract of fifty by twelve miles. Showers of
"flesh" or "blood" have been described in newspapers,
which were probably varieties of Nostoc (page 151), or pig-
ment bacteria (page 326).

The subject of bacteria germs in the air has lately ac-
quired great interest from the success of the antiseptic
method now generally pursued in large surgical opera-
tions, and first introduced by Mr. Lister. This will be
considered under the head of disease germs.

The examination of the breath of men or animals may
be made by means of glycerin on glass slides, or by breath-
ing through a glass tube containing cotton-wool, which
may afterwards be washed with dilute glycerin. Epithe-
lial cells, oil-globules, fragments of food, soot, fungi, etc.,
may thus be detected, or the expired air may be tested
for ammonia with hydrochloric acid.

II. EXAMINATION OF SOIL AND WATER.

The soil may be examined both chemically and micro-
scopically according to the methods given on former pages
of this work. The importance of such examination will
be plain in many cases of local diseases. It is stated that
the mortality caused by murderous epidemics in England

THE MICROSCOPE IN AETIOLOGY. 323

has been greatly diminished since the systematic building
of sewers and the prohibition of pitlike privies in towns.

Dr. Salisbury's observations on the growth of certain
fungi as the cause of malarious fevers, although requiring
further confirmation, suggest a very pertinent line of in-
quiry.

Drinking-water may be vitiated by organic matter and
its chemical products, as ammonia, chlorine, and the ni-
trates. Wagner states that to be drinkable it must not
contain in 100,OuO parts more than 0.4 parts of nitric acid,
0.8 parts of chlorine, and 5 parts of organic matter. Boil-
ing does not improve such water. It is generally made
impure by sewage, and produces gastric and intestinal
diseases, arid perhaps typhoid fever.

III. EXAMINATION OF FOOD, ETC.

The adulteration of food has long been a question of
interest, and has been investigated by a host of observers.
Dr. Hassall's voluminous researches, however, leave little
to be desired. He states that "in nearly all articles,
whether food, drink, or drugs, my opinion is that adul-
teration prevails. And many of the substances emplo37ed
in the adulterating process were not only injurious to
health, but even poisonous." Dr. Hassall's work, Food
and its Adulterations, should be used by all who inquire
into this subject, which is too voluminous to be considered
here in detail. Familiarity, however, with the subjects
already discussed in this work will qualify the observer
for such examinations. Wheat-flour may be examined
by adding a little water, and then a few drops of a solu-
tion of potash (one part liquor potassse to three of water).
Granules of potato-starch swell by this means to three or
four times their natural size, while those of wheat-starch
are scarcely affected by it. Comparisons of different kinds
of starch under the microscope will guide in many other

324 THE MICROSCOPIST.

investigations. Adulteration of flour with alum, etc.,
may be detected by dissolving the alum and recrystalliz-
ing under the microscope.

Coffee is adulterated with chiccory, wheat, corn, etc. ;
tea with foreign leaves, Prussian blue, clay, etc. ; choco-
late with brickdust, peroxide of iron, animal fat, etc.

IV. PARASITES.

Parasites are animal or vegetable organisms which live
temporarily or permanently upon or within another or-
ganism for their nourishment and development. Casual
visitors for the sake of moisture, warmth, or products of
decomposition (as many fungi and infusoria) are called
pseudo-parasites. Van Beneden distinguishes between
messmates which are nourished in common, mutualists
which live on and serve each other, and parasites which
live at others' expense.

In this department of science the student will do well
to consult Cobbold's magnificent work on Entozoa, and
two of the recently published international scientific series
of books, viz., Fungi^y Cooke and Berkely, and Animal
Messmates and Parasites, by Van Beneden.

The plan of Wagner, in his Manual of General Pathol-
ogy', is followed in the present outline, so far as classifica-
tion is concerned.

I. VEGETABLE PARASITES OR EPIPHYTES.
I. FUNGI.

The general character and development of fungi have
been described at page 136. The subject of polymor-
phism also has been referred to as indicating the uncer-
tainty of distinguishing genera and species. Cooke re-
minds us, however, that polymorphism can only be based
upon actual organic continuity, the observance of which
in such minute, organisms is necessarily difficult.

THE MICROSCOPE IN ETIOLOGY. 325

A. DUST OR GERM FUNGI, CONIO OR GYMNOMYCETES.

1. Mycoderma (Cryptococcus). — The beer-yeast (Micro-
coccus, or Torula cerevisice) consists of round or oval color-
less cells containing one, and sometimes two bright nuclei
resembling oil-globules. New cells arise from these by
budding. No proper filament or mycelium is formed.

The milk-yeast (Oidium lactis] can grow fungus-like if
submerged, while on the surface is a mycelium of articu-
lated filaments from which shoots grow up, wrhose cells
separate easily.

Schwann, Pasteur, etc., consider the yeast-fungi as or-
ganisms produced by specific germs, while others regard
them as spores, which in the atmosphere fructify in other
forms.

B. FILAMENTOUS FUNGI, HYPHOMYCETES.

The mycelia of these are lengthened tubular cells, often
branching. The spores originate within or at the end of
filaments. Here belong the fungus of the muscardine of
the silkworm (Botrytis bassiana), the potato disease (Fusi-
porium solani), the grape disease (Oidium tuckerii), mould,
and the fungi occurring in diseases of skin and mucous
membranes.

1. Penicillium glaucum, common mould or pencil mould,
forms most of the mould occurring upon vegetable de-
composing substances. The fruit-bearers rise from a
branched colorless mycelium. The points are tufted and
bear spherical conidia.

2. Aspergillus glaucu?, or green mould, is often found
with the foregoing. The fruit-filaments expand into club-
shaped basidia. The spores are greenish.

3. Mucor mucedo and Mucor racemosus are found on
excrement arid old articles of food. The bladder-like
swollen fruit-hyphen (columella) rises from a branched

326 THE MICROSCOPIST.

filamentous mycelium, which becomes septate with age.
The spores are set free by breaking of the wall of the
sporangium.

C. CLEFT FUNGI, SCHIZOMYCETES (bacterium, micrococcus).

The term schizomycetes is given from the great fra-
gility of the formation. They are cells without chloro-
phyll, of various forms, which increase exclusively by
transverse division. The cell-membrane is not destroyed
by potassa, nor by acids, and resists decomposition for a
long time.

1st Group. Spherobacteria. — Globular bacteria (Pas-
teur's Monas or Mycoderma. Ehrenberg's Monas corpus-
culum and prodigiosa. Hallier's Micrococcus).

Spherical or oval cells, without granular contents, pos-
sessing a double contour, and becoming moniliform by
division. Often difficult to distinguish from granular
detritus.

1st Genus. Micrococcus (Cohn). — Bells colorless or nearly
so, very small, united into short moniliform filaments of
two or more members (mycrothrix, torula-forms), or into
many-celled families, balls, or colonies, or into mucous
masses (zoogloa-forms, mycoderma-forms). No movement.

(1.) Pigment bacteria. Appearing in colored jellylike
masses.

a. Coloring matter, insoluble, red and yellow.

1. Micrococcus Prodigiosus (Palmella prod.). — Cause of
the seeming blood-spots which sometimes appear during
moisture on wafers, bread, potatoes, etc.

2. M. luteus.

b. Coloring matter, soluble. M. aurantiaceus, chlorinus,
etc.

(2.) Zymogenic globular bacteria.

3. Microccocus Urea. — Ferment of urine.

THE MICROSCOPE IN AETIOLOGY. 327

(3.) Pathogenic globular bacteria. " Ferments of con-
tagion."

4. M. vaccines.

5. M. diphthericus

6. M. Septicus. — Some deem it the cause of pyaemia.

7. M. Bombycis. — A destructive epidemic among silk-
worms of Southern France, but different from muscardine
and gattine.

2<f Group. Microbacteria. — Rodlike bacteria, resemble
globular bacteria in the small size of cells and their tem-
porary union into mucous masses, but are distinguished
by their short cylindrical forms and spontaneous move-
ments.

2d Genus. Bacterium.

1. Bacterium Termo. — Cells short, cylindrical, oblong.
They turn on their axis and swim forward, then return a
little or travel in curved lines as if trembling, or spring-
ing forward and then becoming quiet.

2. B. Lineola. — Cells cylindrical, broad, straight, with
refractive soft contents, and fatlike granules. Single or
in pairs.

%d Group. Desmobacteria — Filamentous B. — Filaments
not constricted at the joints, but throughout cylindrical
(leptothrix filaments). May form swarms but not zoogloa-
form masses.

1st Genus. Bacillus. — Filaments straight.

1. B. Subtilis. — Butyric acid ferment.

2. B. Anthracis. — Bacteridia of gangrene of the spleen.

3. B. Ulna.

2d Genus. Vibrio. — Filaments wavy, thick, with single
curve ( V. rugla), or thin, with many curves ( V. serpens).

4th Group. Spirobacteria. — Screw bacteria. Distin-
guished from vibrio by the closer regular permanent spiral
of the filament.

1st Genus. Spirochceta.

1. 8. Plicatilis. — In tartar from the teeth.

328 THE MICROSCOPIST.

2d Genus. Spirillum. — Shorter and more distant spiral.

5th Group.

1st Genus. Leptothrix.

1 L. Buccalis. — Long, brittle, slender filaments, divided
by partition-walls. Occurs on products of decomposition
within the mouth ; papillse of tongue, tartar, etc. Also
in the intestine, vagina, etc. It is thought by some to
produce caries of the teeth.

2d Genus. Sarcina.

1. S. Ventriculi. — Four-fold flat cubical cells, generally
with nuclei. Occurs in vomited fluid, urine, etc.

In addition to the above (provisional) arrangement,
Wagner classifies vegetable parasites with respect to their
pathological relations as follows :

I. MOULD DISEASES.

These are conditional upon the above-mentioned mould
fungi. They occur chiefly upon parts affected with ne-
crosis or other lesions, particularly ulcers of the skin and
mucous membranes. On free surfaces they present an
appearance resembling mould. Perhaps in this connec-
tion belongs the foot-fungus, or Mycetoma Carterii, which
is endemic in India.

II. FUNGI OF TRUE PARASITIC DISEASES OF THE SKIN
AND MUCOUS MEMBRANES.

1. Trico^hyton Tonsurans. — This consists of round trans-
parent spores, or spore-rows. They develop in the roots
of the hair and pass into the shaft, so that the latter is
destroyed and breaks off. It occurs also in the sheaths
of the hair-roots and surrounding epidermis, seldom in
the nails. It causes several diseases, especially of the
scalp and beard, as herpes tonsurans, porrigo scutellate, men-

THE MICROSCOPE IN AETIOLOGY. 329

tagra (sycosis], eczema marginatum, etc. It is thought by
some to proceed from aspergillus.

In examining hair, skin, etc., for fungi, the specimens
should be soaked in liquor potassae long enough to become
transparent.

2. Achorion Schonleinii — Favus Fungus. — Mjcelia com-
posed of small, simple, or branching tubes divided by par-
titions. Spores round or oval, sometimes grouped in
masses. The cause of tinea favosa of the scalp. .

3. Mwrosporon Audouinii. — Undulating forked filaments
on which spores are directly placed. Found round the
shaft of the hair after its exit from the follicle, so thick
that the hair breaks off and causes baldness. Porrigo de-
calvans.

4. Microsporon Furfur. — Masses of large, round, mostly
nucleated spores, and long or branched cells. Sometimes
with numerous broad filaments. Developed in the horny
layer of the epidermis, commonly round the opening of
hair follicles of the breast and back, producing yellowish
discoloration and branlike scales, with itching, — Pityria-
sis versicolor.

5. Oidium Albicans — Thrush Fungus — Tubular fila-
ments, branching stems, and minute spores. Ends of fila-
ments lost in masses of spores, with a large, often divided
spore-cell. Found in aphthae of the mouth, tongue, throat,
vagina, etc.

III. FUNGI AS EXCITORS OF FERMENTATION AND PUTRE-
FACTION AND CAUSES OF DISEASE.

At page 137 the distinction between diseased conditions
which invite fungi and the effects produced by fungi
themselves was stated. ' That fungi are the cause of spe-
cific fermentations (acetic, alcoholic, lactic, butyric, etc.),
is rendered very probable by modern researches, especially
those of Pasteur. In decay, or oxidation, and in putre-

330 THE MICROSCOPIST.

faction of organic bodies, fungi are important agents.
In the former vibrios are found, and in the latter monads
and bacteria. Decay is arrested if access of fungus germs
is prevented. Putrefaction is as dependent on bacteria as
the fermentation of non-nitrogenous bodies upon yeast-
fungi.

Many acute infectious diseases are considered to pro-
ceed from fungi, although the reasons for such an opinion
are chiefly theoretical, arising from the presence of fungi
in those diseases. Such are diphtheria, pyaemia, puer-
peral fever, small-pox, etc. Many experiments have been
made, by inoculation, etc., but thus far with little results.
Observers differ greatly concerning the same disease, the
specific fungus of one being disavowed by another. Still,
much light may be expected respecting aetiology from ob-
servations of this kind.

II. ANIMAL PARASITES.

These inhabit either the external surface (epizoa) or
internal organs (entozoa).

I. PROTOZOA.

GREGARINIDJE. — See page 180. Gregarinidce are para-
sitic animals, generally regarded as the lowest of the pro-
tozoa, although this opinion is doubtful. They usually
consist of a single cell, with an illy-defined membrane
filled with granular and fatty sarcode, with nucleus and
nucleolus. They are developed much like protophytes,
page 140. The gregarina becomes motionless, globular,
and encysted. The nucleus then disappears and the sar-
code breaks up into little masses which become pointed
at each end (pseudo-navicellse). These masses escape as
amoeba, page 121, and develop new gregarince.

Globular psorospermice, as they are called, have been

THE MICROSCOPE IN ETIOLOGY. 331

found in the liver and intestines of rabbits and of man,
and are regarded as the resting stage of yregarince.

INFUSORIA. — Family, Heterotricha. — Body covered with
cilia, often in longitudinal rows. Stronger cilia about
the mouth.

Balantidium Boli. — A common parasite in the rectum
of hosrs. Found sometimes in human intestine.

o

FLAGELLATE. — Infusorial organisms with lashlike cilia.
— .Family, Monadina. Round or oval. Transparent. A
single or few whiplike hairs on anterior extremity.

Cercomonas. — With caudal filament and generally a
single thin and long lash.

C. Intestinalis. — Found in the stools of cholera and
typhoid fever, and on catarrhal mucous membrane of
children.

C. Urinarius. — Urine of cholera and in alkaline albu-
minous urine.

C. Saltans. — On the dirty surface of ulcers.

Trichomonas. — With two or three short cilia near the
anterior lash.

T. Vaginalis. — In the yellow acrid mucus of vaginal
blennorrhoea.

II. VERMES ( Worms).

1st Class. Platodes — Platyelmia. — Flat worms. Bodies
flat, appendages, when present, of suckers and hooks.
Generally hermaphrodite. Many without mouth or in-
testine, nourished by absorption.

1st Order. Cestodes. — Tapeworms. Long, articulated,
flat, without mouth or alimentary canal. Prehensile or-
gans anterior. The anterior part or head is small and
somewhat globular. The neck is thinner. The joints
lengthen and broaden in continuous succession until they
reach their greatest circumference at the posterior ex-
tremity, where they may separate and live independently

332 THE MICROSCOPIST.

as proglottides. The cellular connective parenchyma in-
dexes in its periphery, especially on the head, small chalky
concretions, in all parts the ramifications of a water-vas-
cular system, and in the central parts the sexual organs.
Each segment has its special male and female organs of
generation.

Human tapeworms exhibit a complicated metamorpho-
sis connected with alternate generation. Generally the
ova with the proglottides pass from the intestines and
are conveyed with food into the stomach of an animal.
The embryos become free in the stomach, and by their
movable booklets bore their way into the bloodvessels
and are deposited in various organs, as the liver, muscles,
brain, etc. Here they become encapsulated and grow into
larger vesicles, each of which is a cystworm. From its
covering one (cysticercus) or several (echinococcus) nodu-
lar depressions grow into the interior, on the bottom of
which is the armament of the tapeworm's head, in form
of suckers and hooks. The transportation into the human
stomach is effected by means of food, especially measled
meat. The cyst is digested and the head of the tapeworm
set free as a Scolex. This enters the small intestine, be-
comes fixed, and develops by gradual formation of seg-
ments the tapeworm body.

Family. Tceniadce. — Head pear-shaped or conoidal, with
four round suckers. A rostellum or wreath of hooks be-
tween the suckers or anterior part of head. Proglottides
distinctly separate and generally longer than broad.

A. Vesicular tapeworms, Cysticce. Head rarely un-
armed (T. mediocanellata\ generally with rostellum and
hooks. Middle stern of uterus gives off ramifying side-
branches. Openings of sexual apparatus on the border,
alternate on each side.

a. Vesicular tapeworms, whose heads are formed in
the embryonal state.

1. Tania Solium. — Single, or several together in small

THE MICROSCOPE IN AETIOLOGY. 333

intestine. Develops to from two to three meters long, and
its proglottides ten mm. long and six mm. broad. Head
the size of a pin, globular, with tolerably prominent suck-
ers. Filamentous neck, almost an inch long. The cyst worm
(Cysticercus celluloses] of this species has a preference for
the muscles of the hog, but is found in other animals and
in man.

2. Tee nia Mediocanellata. — Larger than the T. solium.
Head without a circle of hooks and rostellum, but with
powerful suckers. The cystworm inhabits the muscles of
cattle, but has not been found in man.

3. T. Acanthotrias. — The vesicle only is known. Found
in muscles, subcutaneous tissue, and brain of man. Hook
apparatus a triple circle of slender claws.

4. T. Marginata. — Mature tsenioe are like T. solium, but
found in the dog and wolf. The larva abides in the
omentum or liver of ruminants and swine, and sometimes
of man. One extremity of the vesicle is drawn out in a
necklike process, which contains the tapeworm.

b. Cyst tapeworms, whose heads bud from the embry-
onic capsules of the inner surface of 'the vesicle.

5. Tcenia echinococcus consists of only three or four seg-
ments, the last of which exceeds in bulk all the others.
It is three to four mm. long, and its thirty or forty hook-
lets are on a prominent rostellum. It lives in the intes-
tine of the dog. The young state of this Tsenia (echino-
coccus) is an almost motionless vesicle on the inner sur-
face, of which numerous little heads bud in vesicles the
size of a millet-seed. These are sometimes compound
(daughter, granddaughter vesicles\ inclosed one within the
other. In this form they are found in man and cattle
(especially in the liver). Other animals harbor generally
single vesicles.

B. Common tapeworms, Cystoidece. They represent no
peculiar larv?e. Their larvae occur only in cold-blooded
animals or invertebrates. Thus the cysticercoid of T.

334 THE MICROSCOPIST.

elliptica or cucumerina of the dog live in the lice which
infest dogs, and the dogs are infected by eating these lice.
Clinical ly, they are less important than cyst tapeworms.
Head small and hook apparatus imperfect.

a. Head prominence with a single circle of small hooks.

6. Tcenia Nana. — Small. Anteriorly filamentous, but
larger near the middle. Once found in the duodenum of
a boy.

7. T. Flavo Punctata. — 33 cent. long. The anterior half
of immature joints 0.2 to 0.5 mm. long and 1 mm. broad,
which show behind the middle a large yellow spot. The
receptaculum filled with sperm. Head unknown.

b. Papilla with multiple circle of hooks.

8. T. Elliptica. — Usually in dogs and cats.

Family Bothriocephalidce. — Head flattened. Two deep
fissure-like suckers. Articulations imperfectly marked.

9. Bothriocephalus Latus. — The largest human tape-
worm. Sometimes 5 to 8 meters long arid from 3000 to
4000 short and broad joints, seldom more than 3.5 mm.
long, but 10 or 12 mm. broad. The last joints are nearly
square. Anterior end threadlike. Proglottides pass away
in lengths (from 2 to 4 feet). Ova oval, with transparent
shells, and a lid at one end through which the embryo
slips into the water. The six-hooked embryo is developed
several months after the ova are passed.

10. B. Cordatus. — Smaller than B. latus. Head short
and broad, heart-shaped.

2d Order. Trematodes. — Suckerworms. Parasitic solitary
flat worms, with inarticulate leaf-shaped bodies ; with
mouth and bifurcated intestinal canal, without anus,
with abdominal prehensile apparatus. Male and female
organs mostly in the same individual. The distomata
go through a complicated alternate generation and
metamorphosis. The embryos escape from the ova
into water and seek a new animal habitat, mostly
snails. Here they develop into cyst-germs, which are the
parents of the Cercarice, which have a rudder-like tail and

THE MICROSCOPE IN ETIOLOGY. 335

move freely in the water. These enter a new aquatic
animal, snail, worm, crab, or fish, pierce into the tissues
and form a cyst. Thus the young, encysted, sexless disto-
mata arise from the Cercariae, the former received with
the flesh of their supporters into the stomach, and thence
freed from their cyst they enter other organs of another
animal, where they become sexually mature.

Gen. Distomum. — Two suckers on the anterior part.
Genital pores near the abdominal sucker.

a. Body broad and leaf-shaped.

11. Distomum Hepaticum. — Liver-fluke. The Cercarise
are probably encapsuled in fresh- water snails, and eaten
by sheep infect them.. The perfect D. hepaticum inhabits
numerous herbivorous mammals and occurs in man.

b. Body more regular in form, without branched in-
testinal canal.

12. D. crassum.

13. D. Lanceolatum. — Both extremities pointed. Asso-
ciated with D. hepaticum in the bile-ducts.

14. D. Ophthalmobium. — Once found in the crystalline
lens.

15. D. heterophyes.

c. With separate sexual apparatus. Body long and
slender. Female almost cylindrical.

16. D. Hcemalobium. — Oral and abdominal suckers equal
in size. Color white. Is frequent in Egypt, in the veins
as well as intestinal canal and bladder. Feeds on the
blood.

Gen. Monostomum. — Has no abdominal sucker.

17. Monostomum Cutis. — Found once in the lens.

2d Class. Nematelmia. — Roundworms. Bodies rounded,
pouched, or filamentous, without rings or segments.
Sometimes with papillee or hooks on anterior pole Sexes
distinct.

1st Order. Acanthocephali — Vertex bearing hooks. No
mouth or intestine.

336 THE MICROSCOPIST.

18. Echinorrhynchiis. — Inhabits the intestine of several
vertebrates. One found in a leucaemic child.

2d Order. Nematodes. — Threadworms. Bodies round,
threadlike, with mouth and intestine. Armament, when
present, of papillae or spikelets and hooks within the
mouth. Development by single metamorphosis, yet many
young forms have an abode altogether different from that
of their parents, and often the young and sexually mature
inhabit different organs or different animals. Some live
parasitically in plants.

\st Sub- order. Strong yloidce. — JSTernatodes with anus.

1st Family. Ascarides. — Mouth with three lips or pa-
pillae. Sometimes teeth in the throat. Most lay hard-
shelled eggs.

19. Ascaris Lumbricoides. — Roundworm. Cylindrical
body. Male 250 mm. by 3 mm. Female 400 mm. by 5.5
mm. Tail of male conical and hooked.

20. A. Mysto.x. — Smaller than the preceding. Identical
with the common round worm of cats.

21. Oxyuris Vermicular is. — Threadworm. Body fila-
mentous, white. Three lips on the head. Inhabit chiefly
the rectum and large intestine, but may wander to vagina.

2d Family. Strongyloidce. — Mouth generally armed with
a horny surface or hooks.

22. Strongylus Gigas. — Long red worm. Viviparous.
In the pelvis of the human kidney.

23. S. Longevaginatus. — Filamentous, white.

24. S. Armatus. — Cause of the so-called colic of the
horse, which is really aneurism of the intestinal arteries.

25. S. Duodenalis. — -Body cylindrical. Mouth wide,
with two claw-shaped hooks. In Italy and Egypt found
in the intestines by thousands. Gives rise to anaemia, etc.

3d Family. Trichotrachelidce.— Moderately large, longi-
tudinally striated worms.

26. Trichocephcdas Dispar. — Long threadworm. Body
short, 2 cent, long by 1 mm. thick, with filiform neck,

THE MICROSCOPE IN AETIOLOGY. 337

20 to 25 mm. long, and head; in the male spiral, in the
female straight. Generally found in the colon of children
or adults.

27. Trichina Spiralis.—Ou the second day after eating
raw flesh containing trichinae, and after digestion of the
inclosing capsule, the worm is sexually mature Copula-
tion occurs, and on the sixth day after the females bring
forth each about 1000 filamentous embryos. These pierce
the intestinal wall and wander through the tissues to the
voluntary muscles, where they coil up spirally and be-
come encysted. The cysts may become hard and even
calcify. In this state they may remain for years capable
of development. The hog is considered the original
bearer of trichinae, whence they have infected other ani-
mals.

4. Family. Filaridce. — Long filamentous body.

28. Filaria Medicensis. — Threadworm. Guineaworm.
Inhabits the subcutaneous tissue of the foot. Found only
in tropical countries.

3d Class. Annelidce. — Ringed worms. Cylindrical or
flattened. Segmented body with brain, oesophageal ring,
chain of abdominal ganglia and bloodvessels.

Order Hirudinis. — Leech. Body with narrow rings
and terminal disk. No feet. Hermaphrodite.

Sub-order Gnathobdellce. — Gill-leach. Throat with three
often dentated gills. A sort of oval sucker disk in front
of the mouth. Blood mostly red.

29. Hirudo Medicinalis.—tiO to 90 fine teeth on the
free border of the gills. Is three years in arriving to
sexual maturity.

III. ARTHROPODA.

Animals laterally symmetrical. Bodies segmented.
Limbs articulate. Brain and abdominal ganglia present.
Propagation generally sexual.

22

338 THE MICROSCOPIST.

Class Arachnidce. — Air-breathing. Head and thorax
blended. No feelers. Two pairs of jaws and legs. Ab-
domen without members. Sexes distinct.

Order Linguatulidce (Pentastomidee). — Worm-shaped,
ringed. Mouth rounded, with horny border. Four legs,
hooklike and sheathed. Surface hard and pierced by
stigmata. Metamorphosis complete.

30. Pentastomum Tcenioides. — Inhabits the nasal cavities
of the dog and wolf. The larva have been found in man.

31. Pentastomum Denticulatum. — Encapsuled, curved,
calcified. On the surface of the liver, etc.

Order Acarince. — Mites. Body compact, inarticulate.
Mouth for biting, sucking, or stinging. Respiration by
tracheae.

Family Dermatophili. — Hair-follicle rnite. Elongated.
Worm-shaped, fringed abdomen. Suckers and stiletto-
shaped jaws. Four pairs of short bipartite feet.

32. Acarus Folliculorum (Dermodex Folliculorum). —
Found often in ear-wax and sebaceous glands of face.

Family Acaridce. — Mites. Microscopic, soft-skinned.
Legs short, with disks for prehension.

33. Acarus, or Sarcoptes Scabiei. — Itch-mite. Body
round, arched, with transverse striae covered with spines
and bristles. Young have but one pair of feet.

Family Ixodce. — Ticks. Larger, blood-sucking mites,
with firm back-shield and dentated mandibles. Live on
plants, and occasionally on man. The female inserts its
proboscis, and fills itself with blood, causing pain and
suppuration. There are several species.

Family Trombididce. — Running mites. Body brightly
colored, covered with hair. They live on plants, etc., but
sometimes on man. The Leptus autumnalis, gooseberry
or harvest mite, is often troublesome in summer.

Class Hexapoda. — Insects.

Order Rhynchota.

Sub-order Aptera. — Wingless insects, with short, turned-

THE MICROSCOPE IN .ETIOLOGY. 339

in, fleshy beak, and piercing bristles, or with rudimentary
biting mouth. Body has usually nine articulations.

Pediculus Capitis. — Head-louse.

P. Pubis or Phthirius Ingidnalis. — Crabs.

P. Vestimenti. — Clothes -louse.

Sub-order Hemiptera.

Cimex Lectularius. — Bed-bugs.

Order Diptera. — Insects with mouths for piercing or
sucking. Inarticulate thorax, with cuticular anterior
wings. Swing-bats for posterior wings. Complete meta-
morphosis.

Palex Irritans. — Flea.

Pulex or Dermatophilus Penetrans. — Sand-flea. Native
of South America. Breeds under the cutis, and the ova
develop in the sand.

(Estrus Hominis. — Gad-fly. May deposit ova in skin of
man, producing boils.

Musca Vomitoria. — Large, blue-bottle fly.

M. Sarcophaga. — Common flesh-fly.

M. Domestica. — House-fly.

All may deposit ova or fully formed larva in cavities
and wounds.

V. DISEASE GERMS.

The germ-theory of disease ascribes disease, particularly
infectious disease, to the introduction of minute parasitic
organisms into the tissues of the body, and their subse-
quent multiplication there. Many of the early natural-
ists entertained substantially this view, as Vallisneri,
Reaumur, and Linnaeus. It was considered, however, but
a mere hypothesis, until recent microscopic observations
have revived an interest in this direction. Liebermeister,
in his recent monograph on typhoid fever, says, " Within
the last ten years a great revolution has taken place with
regard to the popular signification of a contagium vivum.
New investigations on the appearance, mode of propaga-

340 THE MICROSCOPIST.

tion, and the significance of the low organisms, new facts
in regard to the extension of national diseases, and also a
number of quite positive discoveries by numerous investi-
gators, have removed the old opposition to the theory, or
even been the means of furnishing definite proof of its
correctness." This quotation expresses the most san-
guine views of the adherents of this theory.

We have already referred to the connection of mould
and yeast fungi with the process of fermentation, and it
is quite possible that the introduction of such germs into
the body may produce slight irritations and even inflam-
mations from the increase and multiplication of the fungi,
and the chemical changes induced by them. We have
also seen that fungi are causes of putrefaction as well as
of fermentation in organic bodies. Yet the diseases of
the human body, in which fungi have been proved to be
real causes, are but few. Among vegetable diseases
caused by fungi are the rust, smut, etc., of our grains, the
" vine disease," " potato disease," etc. Among animal
diseases of this kind are some affections of caterpillars,
flies, etc., and gangrene of the spleen in mammals. In
splenic gangrene, however, as well as in mycosis intesti-
nalis, pyaemia, diphtheria, etc., in which fungi occur, the
bacteria may be merely the carriers of the disease, or may
develop because of special pabulum furnished by the dis-
eased structure which is not present in the normal state.

Another theory of disease germs has been published by
Dr. Eeale, which regards them as minute masses of de-
praved bioplasm, originated probably in man's own body,
or in the bodies of some of the animals domesticated by
man.

Both theories may be true in reference to the cases to
which they are applicable. They do not even necessarily
exclude each other. Each kind of disease-germ, bioplastic
or fungoid, may have a range of action peculiarly its own.

Dr. Beale's views seem to apply to a much wider field

THE MICROSCOPE IN ETIOLOGY. 341

of research than the other, and are therefore given here
in abridged form.

Dr. Beale objects to calling disease-germs parasites,
since parasites are organisms themselves, and not mere
particles of living matter. He freely admits the great
variety and rapid growth of microscopic fungi and algae,
and the readiness with which they may enter and traverse
the textures of the body, but considers them to be but
seldom the cause of disease. He says, " In every part of
the body of man and the higher animals, and probably
from the earliest age, and in all states of health, vegetable
germs do exist. These germs are in a dormant or quies-
cent state, but 'may become active and undergo develop-
ment during life should the conditions favorable to their
increase be manifested. There is not a tissue in which
these gerrns do not exist, nor is the blood of man free
from them. They are found not only in the interstices of
tissues but they invade the elementary parts themselves.
Multitudes infest the old epithelial cells of many of the
internal surfaces, and grow and flourish in the very sub-
stance of the formed material of the cell itself. In many
very different forms of disease these germs of bacteria,
and probably of many fungi, are to be discovered in the
fluids of the body, but the evidence yet adduced does not
establish any connection between the germs and the mor-
bid process. The diseases known to depend upon the
growth and development of vegetable organisms are local
affections, and the structure of the organism can be made
out without difficulty, but contagions are general affec-
tions, and no such success attends our efforts to prove
that vegetable organisms are the active agents. In fact,
the fungi which commonly grow on the surface and in
other parts of the body do not produce disease. The germs
of fungi may remain perfectly passive in healthy textures,
growing and multiplying only in those which have already
deteriorated in consequence of disease or old age." .

342 THE MICROSCOPIST.

We have already considered Dr. Beale's views respect-
ing bioplasm — page 118 — as the forming material of the
tissues. At page 246 we have also referred to his doctrine
of inflammation, etc. These views will prepare us to
understand the theory of " disease-germs," considered as
degraded particles of bioplasm. " Degradation in power
is commonly associated with increased rate of growth, and
with remarkable vitality. The actively living degraded
bioplasm may retain its vitality although removed from
the living body, and it may grow and at length destroy
other living organisms to which it gains access." Animal
fluids and secretions, normal as well as those known to
have contagious properties, contain minute particles of
bioplasm, which are sometimes so small as to require the
highest microscopic powers to render 'them visible, yet
they are capable of growth and multiplication to a vast
extent, so that a minute particle of vaccine or other lymph
may originate important changes in a large number of
persons.

The virulent poison of dissection-wounds cannot be as-
cribed to vegetable germs, since it is most virulent shortly
after death of the subject of dissection, and when putre-
factive decomposition has taken place, and bacteria swarm,
the real contagious virus is dead. Such is the vitality,
however, of some forms of degraded bioplasm, that they
will not only multiply on mucous surfaces, but live long
after their removal, as in purulent ophthalmia, gonor-
rhceal pus, etc., so that they may be transported in vari-
ous ways from one place to another and still retain their
multiplying power. A very small portion of blood, serum,
or of the tissues of an affected animal is sufficient to
propagate cattle-plague. Even the breath of the diseased
organism contains numerous virulent particles. There is
reason, also, for thinking that a single epithelial cell may
contain multitudes of active particles in the case of syphi-
litic poison which may remain dormant, perhaps for years,

THE MICROSCOPE IN J3TIOLOGY. 343

or may from time to time give rise to changes peculiar to
it. Particles of living tubercle may be so minute as to be
carried in the atmosphere, although tubercle is not emi-
nently contagious. As to cancer germs, many circum-
stances render it improbable that they can be transmitted,
so that living disease germs differ remarkably in vital
power as well as forms of activity. Yet they resemble
each other in general appearance. Neither by its form,
chemical composition, or other demonstrable properties,
can the vaccine germ be distinguished from the small-pox
germ, or the pus germ from either. All are like the
minute particles of bioplasm of the blood, from which
they differ so remarkably in power. Of the conditions
under which these germs are produced, and of the manner
in which the rapidly multiplying matter acquires its new
and marvellous specific powers, we have very much yet
to learn. For the manner of detecting these germs in the
air, etc., see the former part of the present chapter. Mr.
Lister's excellent plan for the antiseptic treatment of
wounds, and especially the results of carbolic acid spray
in surgical operations, together with many posititive ex-
periments, show that carbolic acid has a powerful action
in arresting vital phenomena or destroying bioplasm. In
its presence embryonic life is impossible ; under its power-
ful influence all minute forms of life perish. Dr. Beale,
also, refers to the effects of carbolic acid, and sulpho-car-
bolates administered internally, in checking the too rapid
growth of bioplasm in the blood and tissues, as well as to
the importance of disinfectants, or the destruction of dis-
ease germs in the air, sewage, etc.

Among the strongest objections to the theorjr of fungoid
disease germs are those given by Dr. Bastian (a strong
supporter of spontaneous generation), that the theory de-
mands a belief in the existence of organisms never known
in their mature state, and whose existence is not demon-
strated but merely presumed ; that such germs have been

344 THE MICROSCOPIST.

experimentally shown to be incapable of producing the
diseases they are assumed to cause ; and that feeding on
putrid flesh, swarming with bacteria, as the Kalmucks do
habitually, produces no injurious consequences. These
objections do not apply to the theory of disease germs
advanced by Dr. Beale, while it will be found to accord
with the most careful and thorough investigation's in
biology and pathology. Yet Beale's views have received
less attention than they deserve, perhaps because of his
pronounced antagonism to the evolutional philosophy,
which is so commonly taught under the guise of natural
science.

APPENDIX. 345

APPENDIX.

RECENT ADDITIONS TO THE MICROSCOPE AND MICROSCOPIC
TECHNOLOGY.

OPTICIANS and microscopists strive continually after
absolute perfection in their instrumental means of re-
search, so that every little while some new piece of ap-
paratus or new method is announced. The most impor-
tant recent additions are named here.

«

IMPROVEMENTS IN MECHANISM.

Some notable improvements have been added to first-
class instruments. Zentmayer's "Centennial" model has
a peculiarly swinging mirror and sub-stage. The mirror-
bar is pivoted in the plane of the object on the stage, so
that illuminating appliances in the sub-stage may be
effected at every angle of inclination, and may even be
brought above the stage as a condenser for opaque objects.
Mr. Bullock, of Chicago, has also adopted a similar plan
in his first-class instruments, and the Bausch & Lomb
Optical Company, of Rochester, New York, place a swing-
ing-bar below the glass stage of their "Professional"
stand, which instrument has many excellent qualities,
although it does not reach the idea proposed by Zent-
mayer.

The latter optician has also adopted this mechanism in
a cheaper form for students in his " Histological Micro-
scope." The "Physician's Microscopes," of the Bausch
& Lomb Company, are also models of cheapness and ex-
cellence. Beck's "National" microscopes are among the
best educational stands.

346 THE MICROSCOPIST.

IMPROVEMENTS IN OBJECTIVES.

A laudable desire to place really good objectives in the
hands of students at a reasonable price has led to great
emulation among opticians. Spencer, Tolles, Wales, Gund-
lach, and the Bausch & Lomb Company, in addition to
their most perfect objectives, both dry and immersion,
which must necessarily demand a high price, have pre-
pared others at less cost for professional and students'
use, which are worthy of all praise. Some of them fall
but little below the performance of the very best glasses.

Test-objects, such as those referred to at page 56, and
which formerly required objectives of best workmanship
and highest power, are now resolved by a large number
of objectives. The J-inch of Spencer or Tolles, the ith of
Gundlach, and even a T40th of Bausch & Lomb, with proper
eye-pieces and illumination, will exhibit nearly all which
can be desired, yet powers of from Jth to T'6th are still
better. For refined histological work 2'gth or -^th, or
even ^gth inch (Tolles), will be found most useful.

The desire to obtain the largest angle of aperture possi-
ble has, however, led to a reduction of the working dis-
tance, or the distance between the object and front of the
objective, so that only the thinnest covers can be used.

For immersion objectives, also, a variety of fluid media
have been proposed, as glycerin, castor oil, oil of cedar,
and kerosene.

IMPROVEMENTS IN EYE-PIECES AND AMPLIFIERS.

Periscopic eye-pieces, consisting of a piano or double
convex field lens and an achromatic meniscus, have been
brought to great perfection by E. Gundlach and the Bausch
& Lomb Company. Solid eye-pieces by Tolles have also
found favor. I have made some improvement in field of
view and definition by substituting a meniscus for the

APPENDIX. 347

field-glass of the periscopic eye-piece. The amplifier re-
ferred to at page 26, or an achromatic concave meniscus,
is added to this form of eye-piece about three inches from
the field-glass. I find this to give better definition than
the amplifiers of Zentmayer and Tolles, which are placed
at the end of the draw-tube.

IMPROVEMENTS IN ILLUMINATORS.

Most of the improvements suggested in illuminators
have been connected with oblique light. In Amici's prism,
Nachet's prism, Reade's condenser, etc., the purpose is to
utilize oblique light and exclude central. In the illumi-
nator proposed at page 35 I have combined a condenser
with an illuminating prism. Mr. Edmunds (after Mr.
"YVenham) has contrived a paraboloid lens with the front
cut off flat and polished. This is in fluid contact with
the under side of the slide. Mr. Wenham's reflex con-
denser, although difficult to use, is capable of excellent
effects. A small lens (plano-convex) placed in immersion
contact with the under side of the slide is also used. Dr.
Woodward's prism, however, for effectiveness and cheap-
ness, bids fair to surpass them all. This is a small right-
angled prism, with its base in immersion contact with the
slide, receiving the light from the mirror or condenser at
right angles to the facet.

The hemispherical condenser and oblique illuminator of
Mr. Gundlach, attached to the "Professional" microscope
of the Bausch & Lomb Company, are also well adapted
for the purpose.

DOUBLE-STAINED PREPARATIONS.

Sections of vegetable tissues present a beautiful appear-
ance under the microscope when doubly stained. They
should first be soaked in alcohol, if green, to deprive them
of chlorophyll, then subjected to a solution of chloride of

348 THE MICROSCOPIST.

lime ( J- ounce to 1 pint of water) until thoroughly bleached.
Soak then in a solution of hyposulphite of soda (1 drachm
to 4 ounces water) for an hour, and after thoroughly wash-
ing in several changes of water transfer them to alcohol.
Prepare some red staining fluid by dissolving J a grain of
magenta crystals in 1 ounce of alcohol. Soak the speci-
men in this for thirty minutes, then rapidly rinse it in
alcohol and place in a blue fluid made by dissolving J
grain of anilin blue in 1 drachm of distilled water, adding
10 minims of dilute nitric acid and alcohol enough to
make 2 ounces. Let the specimen remain only two or
three minutes in this, rapidly rinse in alcohol, put in oil
of cajeput, thence into turpentine, and mount in balsam.
The principle of double staining depends on the affinity
which certain dyes have for certain cells. Thus, if sec-
tions stained in red or green anilin be soaked in alcohol,
and those stained by logwood in alum-water, the color
will leave the loose parenchyma and be retained by the
denser cells, while specimens stained in blue anilin if left
in alcohol, and those stained in carmine if left in water,
lose color more slowly in the parenchyma than in other
parts.

Eosin-staining . — Dilute solutions of eosin, an anilin
preparation, 1 part to 1000 of wTater, has been proposed
for animal tissues, since the different parts are differenti-
ated by different tints. Sections are stained in a minute
to a minute and a half, then washed in water acidulated
slightly with acetic acid, and examined in glycerin; or
they can be mounted in balsam after the water is removed
(see page 80).

CLASSIFICATION OF CRYPTOGAMIA.

In addition to the classification given in previous chap-
ters, the following, chiefly compiled from the Micrographic
Dictionary ', may be useful:

APPENDIX. 349

FERNS.

Order 1. POLYPODIACE.33.— Sporanges on lower sur-
face in groups, but never blended. Annulus present, but
variable.

Family I. POLYPODIODIDE^E.— Numerous sporanges in
sessile sori, divided equally by a vertical annulus.
A. No indusium.

Tribe 1. Polypodiece. — Sori at apices of veins.

* Veins pinnate.

f Margins of fertile fronds not revolute.

Gen. 1. Polypodium. — Sori globose on apex or back of
veins or venules.

Gen. 2. Marginaria. — Sori globose immersed deeply in
backs of veins or venules.

Gen. 8. Pleopeltis. — Sori globose on backs of veins or
venules, with peltate paraphyses concealing the sporanges.

t f Margin of fertile fronds revolute.

Gen. 4. Struthiopteris. — Sori globose on backs of veins
or venules.

* * Veins anastomosing. No free veins in the areolse.
Gen. 5. Dictyopteris. — Sori globose on anastomosing

venules. Venules anastomosing in irregular hexagonal
spots.

* * * Veins anastomosing. Free veins in areolse.
Gen. 6. Niphobolus. — Sori globose on apex of venules.

Venules branched, forming transverse rhomboid spots.

Tribe 2. Acrostichece. — Sporangia scattered over the
whole surface.

Gen. 1. Acrostichum. — Sori on all the veins and paren-
chyma. Veins branched and anastomosing.

Gen. 2. Campium. — Veins branched, with free venules.

350 THE MICROSCOPIST.

Gen. 3. Polybotrya. — Veins pinnate, scarcely anastomos-
ing.

Tribe 3. Tcenitidece. — Sori linear, extending to the areolse
of the leaves.

Gen. 1. Pleurogramma. Sori contiguous on each side of
the rib, parallel, linear, and continuous. Veins simple.

Gen. 2. Tcenitis. — Sori submarginal in middle of disk
of leaf, linear, elongated, and continuous. Veins anasto-
mosing into meshes.

Gen. 3. Notholcena. — Sori marginal, linear, continuous.
Veins pinnate.

Tribe 4. Grammitidece. — Sori linear, confined to the veins
or veinlets.

Gen. 1. Grammitis. — Sori linear or roundish, seated on
certain arms of the veins. Veins simple or forked, scarcely
anastomosing.

Gen. 2. Selligncea. — Sori linear or roundish, on certain
arms of veins. Veins much branched and anastomosing
without free veins.

Gen. 3. Synamnia. — Sori oblong, on back of lowest
venule. Veins branched, anastomosing, with free venules.

Gen. 4. Meniscium. — Sori reniform, on back of trans-
verse venules. Veins pinnate, anastomosing.

Gen. 5. Antrophyum. — Sori imbedded on the back of
all the veins and venules. Veins branched, anastomos-
ing.

Gen. 6. Hemionitis. — Sori on back of veins. Veins
branched, anastomosing in regular meshes.

Gen. 7. Gymnogramma. — Sori on back of veins. Veins
pinnate or forked, scarcely anastomosing.

Tribe 5. Vittariece. — Sori in the grooved margin, which
simulates an indusium.

APPENDIX. 351

Gen. 1. Vittaria. — Sori solitary. Fronds ribbonlike or
grassy.

B. With an indusium.

Tribe 6. Adiantece. — Sori linear, marginal, at apices of
veins. Indusium spurious, formed by revolute margin.

* Sori on the notches of the fronds.

Gen. 1. Lonchitis. — Veins anastomosing. Sori linear,
semilunate. Indusium marginal, semilunar.

Gen. 2. Hypolepis. — Veins primate. Sori sub-globose,
on inferior border of teeth of frond. Indusium margi-
nal, semilunar.

* * Sori on margin of the frond.

Gen. 3. Lomaria. — Veins primate, forked ; fertile fronds
narrower. Sorus linear, continuous.

Gen. 4. Pteris. — Veins primate. Sorus continuous.

Gen. 5. Amphiblestra. — Primary veins strong. Venules
anastomosing in hexagonal spots. Sorus linear.

Gen. 6. Litobrochia. — Veins anastomosing hexagonally.
Sorus linear.

Gen. 7. Allosorus. — Veins primate. Sori at first roundish,
then confluent and linear, covered by the reflected margin.

Gen. 8. Cassebeera. — Veins primate. Sori two under
each notched tooth of the leaf.

Gen. 9. Adiantum. — Veins fan-primate. Sori linear or
semilunar, free within.

. Gen. 10. Hewardia. — Veins reticulated. Sori linear.
Indusium linear or semilunar.

Gen. 11. Cheilanthes. — Veins primate. Sori sub-globose,
minute, covered by reflexed apex of tooth and the indu-
sium.

Tribe 7. Dicksoniece. — Sori globose, apical. Indusium
lateral, two-valved.

Gen. 1. Dicksonia. — Valves of indusium unequal.
Gen. 2. Cibotium. — Valves nearly equal.

352 THE MICROSCOPIST.

Gen. 3. Cystodium. — True indusium plane, false one
hood like.

Gen. 4. Thrysopteris. — Sori serniglobose. Indusium cup-
like. Sori on a thrjse (leaf without parenchyma).

Gen. 5. Deparia. — Sori as in 4. Parenchyma of leaf
developed.

Tribe 8. Dawttiete. — Sori apical, inframargiual. Indu-
sium one-valved.

Gen. 1. Davallia. — Sori globose. Indusium cup-shaped,
the mouth truncated. Veins primate.

Gen. 2. Lindscea. — Sorus linear, continuous. Indusium
parallel with leaf margin, free outside. Veins dichoto-
mous.

Gen. 3. Dictyoxyphium. — Sorus and indusium as in 2.
Veins anastomosing with free venules.

Gen. 4. Schizdoma. — Sorus and indusium as in 2. Veins
anastomosing in hexagonoid meshes.

Tribe 9. Aspleniece. — Sori on veins. Indusium persist-
ent, lateral, the margin free.

Gen. 1. Scolopendrium. — Veins primate. Sori linear, in
pairs on adjacent sides of two parallel veinlets.

Gen. 2. Antigramma. — Veins primate, veinlets anasto-
mosing. Sori linear, in pairs facing together.
. Gen. 3. Camptosorus.— Veins as 2. Sori elongated, di-
verging.

Gen. 4. Diplazium. — Veins primate, veinlets free. Sori
linear, in pairs back to back.

Gen. 5. Oxygonium. — Veins primate, veinlets anasto-
mosing at the ends. Sori as 4.

Gen. 6. Asplenium. — Veinlets free. Sori linear, single
on back of vein or veinlet.

Gen. 7. Ceterach. — Indusium replaced by scales. Sori
linear on back of veins.

Gen. 8. Neottopteris. — Veinlets anastomosing at ends.
Sori linear, single.

APPENDIX. 353

Gen. 9. Aihyrium. — Veins primate. Sori straight, curved,
or reniform, but attached by a linear edge.

Gen. 10. Bleehuwn. — Sori marginal, somewhat conflu-
ent. Indusium opening inwards.

Gen. 11. Doodia. — Veins parallel, anastomosing slightly.
Sori lunate or linear, in one or two rows parallel with
midrib. Indusium flat.

Gen. 1 2. Woodwardia. — Vein lets form hexagonal meshes.
Sori lunate or linear, parallel with midrib in one row.
Indusium convex, immersed.

Gen. 13. Cystopteus. — Indusium suborbicular, fixed by
a lateral inferior point.

Gen. 14. Onoclea. — Fertile pinme contracted into glob-
ules. Indusium lunate, attached on a short horizontal
veinlet.

40

Tribe 10. Aspidiece. — Sori subglobose. Indusium with
central or eccentric point of attachment, free all round.

Gen. 1. Lastrcea. — Indusium reniform. Yeinlets free
at ends.

Gen. 2. Nephrolepis. — Indusium reniform. Sori on tips
of upper veinlets. Petioles articulated with the rachis.

Gen. 3. Nephrodium.— Indusium reniform, veinlets in-
osculating.

Gen. 4. Aspidium. — Tndusium orbicular, peltate. Veins
branched, anastomosing hexagonally, with free veinlets.

Gen. 5. Polystickum. — Indusium orbicular, peltate. Sori
on middle of veins below the bifurcations.

Gen. 6. Sagenia. — Indusium orbicular, peltate. Vein-
lets anastomosing hexagonally without free ringlets.

Gen. 7. Fadyenia. — Indusium cordate. Sori apical, bi-
seriate. Veinlets reticulate.

Gen. 8. Didymochlcena. — Indusium oblong-elliptic, fixed
in the middle by a longitudinal crest.

Gen. 9. Matonia — Indusium orbiculate, peltate, umbo-
nate, the margins deflexed, covering about six sporanges.

23

354 THE MICROSCOPIST.

Tribe 11. Peranemece. — Indusium inferior, ultimately
lobed or ciliated.

Gen. 1. Peranema. — Sori pedunculate. Indusiura cup-
shaped, splitting into 2-4 lobes. Sporanges on punctiform
receptacle. Veins pinnate.

Gen. 2. Diacalpe. — Sori regular. Indusium sessile,
spherical, at first closed. Sori on a punctiform receptacle,
then bursting irregularly at the summit.

Gen. 3. Woodsia. — Sporanges pedicellate, inserted at
bottom of indusium which is cup-shaped and hairy at
margin. Veins pinnate.

Gen. 4. Bypoderris. — Sporanges on -almost obsolete axis-
Indusium cup-shaped, fringed at margin. Veins anasto-
mosing.

family II. CYATH^EJE. — Numerous sporanges, united
in sori on a salient axis, with a somewhat oblique annulus.

A. Sori without indusia.

Gen. 1. Alsophila. — Sori globose, regularly arranged.
Sporanges on globose axis and imbricated.

Gen. 2. Trichopteris. — Sori globose, regularly arranged,
laterally confluent. Sporanges on globose axis, areolate
and crinite with long hairs.

Gen. 3. Metaxya. — Sori globose, each fertile vein bear-
ing several, irregularly scattered. Sporangia on globose
axis, beset with long articulated hairs.

B. Sori indusiate.

Gen. 4. Hemitelia. — Sori globose, each solitary on a
pinnule. Indusium an ovate, concave, torn scale, at lower
side of the base.

Gen. 5. Cnemidaria. — Sori globose, regularly arranged.
Indusium forming an involucre, at length irregularly torn
or partite.

Gen. 6. Cyathea. — Sori hemispherical, regular. Indu-
sium first closed, then bursting and cup-shaped.

APPENDIX. 355

Gen. 7. Schizoccena. — Sori regular. Indusium of six
lobes surrounding the globose receptacle.

Family III. GLEICHENIE^I. — Sporanges united in fours
into sori, and surrounded by an oblique annulus, like a
turban.

Gen. 1. Gleichemia. — Sporangia in roundish sori. Indu-
sium absent. Leaves forking.

Gen. 2. Platyzoma. — Sporanges in pointlike sori. In-
dusium spurious, formed by revolute margin of leaf,

leaves undivided.
•

Family IV. PARKERLELE. — Sporanges ununited into sori,
and divided, equally by a vertical annulus.

Gen. 1. Ceratopteris. — Sporanges surrounded by a broad,
complete, articulated annulus, placed on longitudinal
veins. Spores globose, trifariously streaked.

Gen. 2. Parkeria. — Sporanges with almost obsolete
basilar annulus, or longitudinal veins. Spores three-sided,
concentrically streaked.

Family V. OSMUNDEJE. — Sporanges united in sori, and
covered on the back by a broad and imperfect annulus.

Gen. 1. Osmunda. — Sporangia on metamorphosed pin-
nules.

Gen. 2. Todea. — Sporangia on unchanged pinnules.

Family VI. SCHIZ^EE^:.: — Sporanges united in sori, and
annulus like a skull-cap with radiating streaks.

Gen. 1. Aneimia. — Sporangia twin, sessile in two rows,
on lateral lobes of leaf, contracted into a panniculate im-
marginate rachis, naked, splitting longitudinally outside.
No indusium.

Gen. 2. Schiz&a. — Sporanges sessile in two or four rows
in linear membranous-margined lobes, pectinately oppo-

356 THE MICROSCOPIST.

site or digitate at apex of leaf, set among hairs, splitting
longitudinally on the outside. No indusium.

Gen. 3. Lygodium. — Sporangia sessile, alternately bi-
seriate on marginal lobes of leaf, splitting longitudinally,
each veiled by a scalelike, hood-shaped indusium adhering
transversely to the nerves.

Gen. 4. Mohria. — Sporangia sessile in one row, close to
margin of leaf, splitting longitudinally on the outside. A
spurious indusium formed by revolute margin of leaf.

Order 2. MA RATTIACE^.— Sporanges on lower sur-
face, usually blended together, or very closely approxi-
mated. No annulus.

Gen. 1. Angiopetris. — Sporangia in two rows near apex
of transverse veins, distinct, forming linear sori, opening
by a slit on outer side. No indusium.

Gen. 2. Kaulfussia. — Sporangia on anastomoses of
veins, radiately connate, forming roundish sori, opening
by a slit at apex.

Gen. 3. Marattia. — Sporangia in two rows near apex of
transverse veins, connate, forming oblong sori, gaping
transversely by a vertical slit. Indusia connate with
sori.

Gen. 4. JEupotium. — Sporangia as 3, but pedicellate.

Gen. 5. Dancea. — Sporangia in two rows, near trans-
verse veins, connate into linear sori, opening by a pore.
Indusia superficial, encircling the sori.

Order 3. OPHIOGLOSSE^E.— Sporanges on lower sur-
face of leaf (reduced to mere ribs), never blended. No
annulus.

Gen. 1. Ophioglossum. — Sporanges dehiscing transversely,
connate on an undivided distichous spike.

Gen. 2. Botrychium. — Sporanges as last, on a distichous,
secund, bi-tri-pinnate spike.

Gen. 3. Helminthostackys. — Sporanges dehiscing exter-

APPENDIX. 357

nally, vertically, from base to middle, collected in whorls,
with crestlike appendages, and stalked, arranged distich-
ously on an elongated spike.

Order 4. HYMENOPHYLLE^E.— Sporanges attached
to a common stalk, prolonged from end of vein of leaf,
and contained in a kind of cup formed by a lobe of leaf
above and indusial lobe from lower surface of leaf.
Obliquely transverse annulus.

Gen. 1. Trichomanes. — Sporanges sessile around base of
an exserted filiform column projecting from margin of
leaf, surrounded by a cup shaped indusium continuous
with leaf.

Gen. 2. Hyme.nophyllum. — Sporanges sessile up to sum-
mit of a column projecting from the margin of the leaf,
sub-elevated, but not exserted beyond the indusium, which
is two-valved.

Gen. 8. Loxsoma. — Sporanges stalked, inserted up to
summit of a sub-elevated exserted column in margin of
leaf, surrounded by an indusium, with truncated mouth,
entire.

MICROSCOPIC FUNGI.

Order COKIOMYCETES.— The mycelium may be short
filaments converted into spores, or a flocculeut patch in
decaying matter or under the epiderm of plants, or more
completely organized into hollow conceptacles containing
spore-bearing filaments.

Family I. SPHJERONEMEI. — Conceptacles rising from mi-
croscopic mycelia growing beneath the epidermis of leaves,
stems, etc., containing a chamber lined by a perithecium
bearing single, often septate spores, and bursting by a pore
at the summit.

Gen. 1. Coniothyrium. — Conceptacle free, membranous,
opening by an irregular pore at the summit. Spores
globular.

358 THE MICROSCOPIST.

2. Leptostroma. — Conceptacle innate, subumbonate in
the centre, dimidiate, at length falling off, leaving a thin
disk.

3. Phoma. — Conceptacle ostiolate, very thin, innate,
immersed, rounded, with a simple pore. Spores oblong,
simple.

4. Leptothyrium. — Conceptacle operculate, innate, shield-
shaped, not radiate-fibrous. Spores spindle-shaped, simple.

5. Aetinothyrium. — Conceptacle operculate, innate, etc.,
as 4.

6. Microthecium. — Conceptacle indehiscent, membranous,
immersed, endophytic. Spores simple.

7. Cryptosporium. — Conceptacle membranous, opening
irregularly at summit. Spores spindle-shaped, simple.

8. Sphceronema. — Conceptacle horny, inn-ate-superficial,
produced into a neck, ostiole simple. Spores oblong,
simple.

9. Acrospermum. — Conceptacle leathery externally,
fleshy within, elongate-clavate, ostiole simple. Spores
stick-shaped, simple.

10. Diplodia. — Conceptacle horny, innate-superficial or
immersed, perforated by a pore or irregularly opened or
ostiolate, ostiole more or less produced. Spores ovoid or
ellipsoid, double, then halved into compressed-ternate
semi-ellipsoid sporules.

11. Hendersonia. — Conceptacle fleshy, innate superfi-
cially or immersed, perforated by a pore, opening irregu-
larly or ostiolate, ostiole produced. Spores globose, cylin-
drical or discoid.

12. Septoria. — Conceptacle horny, innate-immersed,
rounded, ostiole simple. Spores cylindrical, septate.

13. Vermieularia. — Conceptacle bristly, depressed,
bursting irregularly. Spores minute, linear.

14. Neottiospora. — Conceptacle immersed. Spores ap-
pendaged at one end with short hyaline threads.

15. Asteroma. — Conceptacle very small, slightly promi-

APPENDIX. 359

neut, close, subconfluent, seated on more or less radiating
fibrils.

16. Discosia. — Conceptacles innate, somewhat carbona-
ceous, at length collapsed and plicate, ostiole perforated.
Spores fusiform, produced at both ends into a threadlike
point.

17. Prosthemium. — Conceptacles horny, immersed, os-
tiole simple. Spores transversely septate, verticulate at
the apex of thin filaments.

18. Angiopoma.— Conceptacles free, membranous, some-
what horny, cup-shaped, dehiscing by a circular mouth,
provided with a fugarious epiphragm. Spores affixed at
base, stalked, septate.

19. Piggotia. — Conceptacles irregular, thin, obsolete be-
neath, confluent, bursting by irregular crack; spores on
short stalks, largish, obovate, somewhat constricted at
base.

20. Phlyctcena. — Conceptacle spurious, formed by the
blackened epidermis ; spores fusiform, cuspidate, septate,
accompanied by a gelatinous mass.

21. Glceosporium. — Conceptacle absent ; spores covered
by cuticle which separates ; spores stalked, elliptical, sim-
ple, exuding a gelatinous tendril.

22. Dilophosphora. — Conceptacle immersed in a spurious
stroma, covered, perforated by a pore ; spores cylindrical,
continuous, crowned at both ends with radiating filiform
appendages.

23. Sphceropsis. — Conceptacle spherical, immersed, sub-
innate, astomous, bursting by separation of epidermis or
irregularly. Spores simple.

Family II. MELANCONIEI. — Conceptacles as in the pre-
ceding, but without a proper perithecium ; spores elon-
gated.

Gen. \. Sporidia globose, simple, adhering to form a
nucleus, at length breaking out free. Color black.

360 THE MICROSCOPIST.

2. Papularia. — Sporidia quite simple, collected in groups
under epiderm of dead plants, set free in a pulverulent
patch by the decay of the epidermis.

3. Stilbospora. — Sporidia septate (septa evanescent), full
of sporidiola, adhering in a nucleus, at length breaking
out.

4. Didymosporium. — As the last, but the sporidia didy-
mous (septate in middle). Color black or fuscous.

5. Cytispora. — Sporidia simple, stick-shaped, minute, in
a multilocular nucleus, at length opening by a common
apical pore and emerging as a gelatinous tendril.

6. Melasmia. — Sporidia minute, stick-shaped, in a flat,
thin nucleus, which bursts at apex and extrudes the spores
in a gelatinous globule.

7. Micropera. — Sporidia linear, curved, formed in nu-
clei, bursting by distinct pores, and discharged mixed with

jelly.

8. Ceuthospora. — Sporidia simple, ovate, contained in
several globose nuclei in a common stroma, escaping by a
simple lancinate pore.

9. Nemaspora. — Sporidia simple, spindle-shaped, in nu-
clei in a common grumous stroma and opening by a com-
mon pore.

10. Discdla. — Sporidia elongated, simple or uniseptate,
stalked, in a nucleus with perithecium.

11. Cylindrosporium (Glceosporium). — Sporidia simple,
elliptical, stalked, in nucleus covered only by cuticle of
leaf, finally extruded in a gelatinous tendril.

12. Coryneum. — Sporidia spindle-shaped, multiseptate,
stalked, crowded, breaking out on surface as a pulvinate
disk.

13. Bactridium. — Sporidia spindle-shaped, multiseptate,
transparent at ends, tufted on a superficial creeping my-
celium.

14. Eriospora. — Sporidia filiform, originally attached in

APPENDIX. 361

fours upon sporophores, in groups of globose nuclei open-
ing by a common pore.

15. Cheirospora. — Sporidia simple, crowded in tufts at
apex of a filiform sporophore, in moniliform rows.

Family TIL PHRAGMOTRICHACE^E. — Conceptacles horny,
breaking through epidermis of leaves, etc., at first closed,
then bursting longitudinally ; spores septate, and in chain-
like series, with paraphyses on internal walls of concep-
tacles.

Gen. 1. Endotrichvm. — Conceptacle innate or immersed,
bursting by a longitudinal slit ; spores globular, simple.

2. Schizotkedum. — Conceptacle superficial, bursting
laterally; spores globular, simple.

3. Pilidium. — Conceptacles simple, sessile, rounded,
bursting by stellate fission ; spores spindle-shaped, simple.

4. Exdpula. — Conceptacle cup-shaped, membranous,
sessile, naked ; spores spindle-shaped.

5. Dinemasporium. — Conceptacle cup-shaped, membra-
nous, sessile, closed by villi, and at length open ; sporige-
nous layer discoid, dissolving, with cylindric, elongate,
filiform spores.

6. Myxormia. — Conceptacle thin, cup-shaped, open,
formed of elongated cells. Pedicels of spores delicate.
Spores oblong, chained together, at length free, involved
in mucus.

7. Cystotricha. — Conceptacle bursting by a longitudinal
slit ; pedicels of spores branched, articulate, somewhat
beaded.

8. Bloxamia. — Conceptacle delicate, hyaline, upper part
evanescent and forming a rim. Spores quadrate in crowded
tubules.

9. Phragmotrichum. — Conceptacle horny, carbonaceous,
at first closed, then splitting by longitudinal fissure ;
fertile filaments mixed with inarticulate paraphyses;
spores compound and chained in series.

362 THE MICROSCOPIST.

Family IV. TORULACEI. — Mycelium filamentous, grow-
ing on the surface of decayed vegetables, bearing erect
filaments, terminating in rows of simple or compound
spores.

Gen. 1. Torula. — Spores in beaded chains, simple, readily
separating, placed on short continuous or septate pedicel.

2. Bixpora. — Spores uniseptate.

3. Septonema. — Several transverse septa in the spores.

4. Alternaria. — Cellular spores connected by filiform
isthmus.

5. Sporidesmium. — Spores in tufts, straight, subclavate
or fusiform, shortly stalked or sessile, transversely sep-
tate or cellular.

6. Sporochisma. — Filaments erect, simple, external mem-
brane inarticulate. Spores articulate in fours.

7. Tetraploa. — Spores sessile, quadriseptate, in bundles
of four, each crowned with a bristle.

8. Coniothecium. — Spores without septa, in heaps, finally-
separating into a powder.

9. Echinobotryum. — Spores rounded apiculate, in fasci-
cles, or erect annulated filaments.

10. Sporendonema. — Erect filaments with single rows
of spores in the interior.

11. Spiloccea. — Spores globose, adhering together and to
the matrix, forming spots laid bare by separation of epi-
dermis.

12. Achorion. — Mycelium ramose, articulated, joints
terminating in round, oval, or irregular spores (conidia?).

13. 8peira. — Spores connate in concentric filaments,
forming horseshoe-like lamina, finally separating.

14. Trimmatostroma. — Spores curved, multiseptate, in
beaded rows, separating.

15. Gyrocerus. — Spores connate in spirally coiled fila-
ments, separating.

16. Dictyosporium. — Spores tongue-shaped, reticularly
cellular.

APPENDIX. 363

Family V. UREDINEI. — Mycelium a filamentous mass
growing in the interior of living vegetable structures,
finally breaking out on the surface in patches, margined or
naked, and bearing simple or compound spores, single or in
beaded series.

The following is Tulasne's synopsis of the family :

I. Albyginei (white or pale-yellow, heterosporous).

Gen. 1. Cystopus.

II. JEddinei (with a peridium, homcesporous).

2. Caeoma.

3. ^Ecidium.

4. Rsestelia.

5. Peridermium.

III. Melampsorei (solid, pulvinate, biform).

6. Melampsora.

7. Coleosporium.

IV. Phragmidiacd (pulverulent, biform, infuscate).

8. Phragmidium.

9. Triphragmidium.

10. Puccinia.

11. Uromyces.

12. Pileolaria.

Y. Pucdniei (fleshy, ligulate or tremelliform, naked,
and uniform in the fruits).

13. Podisoraa.

14. Gymnosporangium.

VI. Cronartiei (peridiate, biform, ligulate).

15. Cronartium.

Family VI. USTILAGINEI. — Similar to the last, but grow
in the interior of organs, especially ovaries and anthers,
of plants. Spores break up without bursting through to
surface, so as to leave a cavity full of dustlike spores.

I. Ustilagind Veri. — Stroma at first mucilaginous, en-
tire, or soon bro&en up into variously conglomerated

364 THE MICROSCOPIST.

masses, then into unappendaged spores ; few or no fila-
ments persistent.

1. Ustilago. — Spores simple.

2. Thecaphora. — Spores compound.

II. Tilletiei. — Stroma of interwoven fragile filaments ;
spores acrogenous on their ramules, often appendaged
when free.

3. Tittetia.

Order HYPHOMYCETES. — Mycelium filamentous,
growing as moulds over dead or living organic substances.
The erect filaments bear terminal, free, single, simple, or
septate spores.

Family I. ISARIACEI. — Receptacle clavately branched,
of filaments attached in their whole length. Spores sim-
ple, attached to simple pedicels.

Gen. 1. Isaria. — Receptacle of interwoven filaments,
or cellularly fleshy. Spores on simple sporophores arising
on all sides.

2. Anthina. — Receptacle of parallel filaments, feathery
or villous at the summit where they form the sporo-
phores.

8. Ceratium. — Receptacle horn-shaped, mucilaginous,
with filaments which collapse into granules (conidia), and
free sporidia.

Family II. STILBACEI. — Receptacle wartlike or clavate
above, stalked below, of filaments packed, coherent, ter-
minating singly in free spores.

Gen. 1. Stilbum. — Receptacle clavate or capitate at sum-
mit. Spores simple.

2. Pachnocybe. — Receptacle stipitate, clavate, floccose,
filaments twisted, head finally pruinose, with simple
spores.

3. Periconia. — Receptacle of coalescent crowded, paral-

APPENDIX. 365

lei filaments, or cellularly fleshy ; spores simple, crowded,
on simple sporophores arising at summit and on the
stalk.

4. Tiibercularia. — Receptacle fleshy, of continuous sterile
arid threadlike beaded fertile filaments. Finally indurated,
floccose, with spores scattered over it, or falling into
powder.

5. Periola. — Receptacle cellular , sessile, fertile filaments
abbreviated, torulose, mixed with septate lax sterile fila-
ments.

6. Volutella. — Receptacle cellular, compact, with long
rigid bristles ; spores spindle-shaped, septate, on continu-
ous short filaments, all over the receptacle.

7. Fusarium. — Receptacle cellular, gelatinous ; spores
spindle-shaped, simple, somewhat curved, on simple fila-
ments forming a discoid stratum.

8. Illosporium. — Receptacle sub-gelatinous, diffluent ;
spores simple, pellucid, generally with hyaline envelope
on short filaments.

9. Epicoccum. — Receptacle cellular, on effused patch ;
spores four-sided, cellular, singly to short filaments.

Family III. DEMATIEI. — Mycelium filamentous, spores
compound or simple, rising from apices of erect, solid, cor-
ticate, subopaque filaments, or produced from solution of
the plants.

Gen. 1. Cephalotrichum. — Fertile filaments stalklike,
erect, septate, terminating in a globose capitule formed
by radiating forked or ternate branches bearing globular
spores at the tips.

2. Sporocybe. — Filaments fibrous, subulate, capitate,
with simple spores conglobated into a terminal head.

3. (Edemium. — Filaments rigid, erect, almost continu-
ous, or annulated, bearing at the sides globular masses of
spores.

4. Myxotrichum. — Filaments erect, scarcely septate ;

366 THE MICROSCOPIST.

fertile branches crowned by globules of heterogeneous eon-
glutinated spores.

5. Bolacotricha. — Filaments simple, uniformly articulate
at apex; spores conglomerate, large, globular, shortly
stalked, contents granular.

6. Helminthosporium. — Filaments erect, simple, septate ;
spores transversely septate.

7. Triposporium. — Filaments erect, septate, sterile
branches solitary, more or less spreading ; fertile branches
shorter, at tips solitary, stellate, shortly stalked spores.

8. Helicosporium. — Filaments subulate, closely septate,
diaphanous at summit ; spores threadlike, septate, spirally
coiled, then expanding elastically.

9. Cladotrichum. — Filaments septate, branched, branches
and branchlets with septate spores at tips.

10. Dematium. — Filaments septate, with verticillate
branchlets below, simple and whiplike above ; spores
crowded on apices of ramules.

11. Cladosporium. — Filaments septate above, bearing
spores in rows forming short moniliform branchlets.

12. Macrosporium. — Filaments suberect, septate, deli-
cate, evanescent, with erect stipitate spores, with many
transverse and usually some longitudinal septa.

13. Arthrineum. — Filaments tufted, suberect, annulate
with opaque septa ; spores fusiform, septate, large.

14. Camptoum. — Filaments as preceding ; spores ovate,
curved, small.

Family IV. MUCIDINES. — Mycelium filamentous, spores
solitary, or crowded on articulated or branched tubular
and pellucid filaments, soon separating and mingling with
the mycelium or adherent in chained rows (moulds, mil-
dews, etc.).

A. Fertile filaments (pedicels) simple or branched, ter-
minating in single spores, or a short row.

* Spores simple.

APPENDIX. 367

1. Botrytis. — Pedicels erect, septate, branched ; branches
and branchlets septate ; spores solitary, on tips of branch-
lets, which are racemose, umbellate, cymose, etc.

2. Peronospora. — Like 1, but pedicels without septa.

3. Verticillium. — Pedicels erect, septate, with whorled
branches terminating in a solitary spore or a short row of
spores.

4. Acremomum. — Pedicels short, subulate, branches from
a horizontal filament, bearing single smooth spores.

5. Zygodesmus. — Like 4, but with echinulate spores.

6. Oidium. — Pedicels simple, short, erect, clavate, sep-
tate, with one, sometimes two, oval spores.

7. Pasidium. — Spores elongate, fusiform.

8. Menispora. — Pedicels erect, septate, with fusiform
or cylindric spores, at first joined in bundles.

9. Sceptromyces. — Pedicels erect, geniculate, verticil-
lately branched ; branches short, racemose ; spores in
grapelike bunches.

* * Spores septate.

10. Brachydadium. — Pedicels branched above, septate,
moniliform ; branches and branchlets forming a sporifer-
ous capital urn ; spores transversely septate.

11. Trichothedum. — Pedicels in tufts, the central erect,
fertile ; spores acrogenous, didymous, free, commonly
loosely heaped.

12. Cephalothecium. — Pedicels simple, continuous, with
terminal head of didymous spores.

B. Erect filaments (pedicels) terminating in strings of
spores.

* Spores simple.

13. Penicillium. — Pedicels erect, septate, penicillately
branched above ; branches and branchlets septate ; strings
of spores at tips of branches.

14. Sporotrichum. — Pedicels simple or slightly branched,
septate and articulate, articulations remote, inflated ;
spores simple, usually in heaps among the filaments.

368 THE MICROSCOPIST.

15. Briarea. — Pedicels septate, with terminal monili-
form chains of spores, crowded into a head,

16. Gonatorrhodum. — Pedicels septate, with chains of
spores in a terminal head, and in whorls at the joints.

* * Spores septate.

17. Dendryphium. — Pedicels septate, unbranched ;
strings of spores in a bunch at apex ; spores septate.

18. Dactylium. — Pedicels septate, branched above;
strings of septate spores singly or in pairs, at apices of
branches.

C. Fertile filaments (pedicels) inflated at the tips or at
various points in their length, with projecting points or
warts, on the inflations bearing

* Simple spores.

19. Aspergillus. — Pedicels continuous, erect, simple fila-
ments, inflated into a little head at the summit, bearing
moniliform chains of spores, crowded into a capitulum.

20. Rhinotrichum. — Pedicels erect, septate, sometimes
sparingly branched, the apices clavate, cellular, bearing
scattered points supporting simple spores.

21. Papuloespora. — Pedicels short lateral branches from
a creeping filament, terminating in cellular heads beset
with spores on the areolae.

22. Rhopalomyces. — Pedicels erect, not septate, termi-
nating in cellular heads, with simple spores on the areolre.

23. Stachylidium. — Pedicels articulate, whorled-branched
above ; branches geniculate and articulate ; spores sub-
pedicilate, in little heads inserted at tips of branches.

24. Gonatobotrys. — Pedicels septate, with joints swollen
at intervals, the swollen joints bearing globular heaps of
spores on short spines spirally arranged.

25. Acmosporium. — Pedicels septate, branched above ;
branches and branchlets forming a cyme, thickened at the
apex, and furnished with globular capitules covered with
points ; spores attached on the points of capitules.

APPENDIX. 369

26. Haplotrichum. — Pedicles septate, terminating in con-
tinuous, solitary, sporiferous head.

27. Actinodadium. — Pedicles septate, umbellately
branched at summit ; spores accumulated at tips of
branches.

28. Botryiosporium. — Pedicles septate, with short spine-
like branchlets above, spirally arranged, and terminating
in four or five short points which support globular heads
of spores.

* * Spores septate.

29. Arthrobotrys. — Pedicles simple, septate, with joints
swollen at intervals and clothed with spines bearing didy-
mous spores in globular heaps.

5. Family Sepedoniei.— Mycelium filamentous, spores
usually heaped together on the mycelium, and apparently
springing out of it, without erect pedicles.

1. Artotrogus. — Filaments creeping, persistent; spores
from middle of filaments, simple, at length free, spinous.

2. Sepedonium. — Filaments woolly, septate, evanescent;
spores globose, connate, scabrous, stipitate, solitary, at
length heaped together.

3. Fussisporium. — Spores fusiform or cylindrical, glued
in heaps on the gelatinous matrix.

4. Epoehnium. — Spores heaped, oblong, apiculate, sep-
tate, adnate to the matrix, interwoven with effused,
tangled, slender filaments of mycelium.

5. Psilonia. — Spores simple, pellucid, not glued together,
at first covered with conveying filaments of mycelium.

6. Monotospora — Eutophyte. — Filaments creeping, evan-
escent ; spores globose, solitary, terminal, at length free.

7. Asterophora. — Filaments creeping (over larger fungi) ;
spores on short ramules, vesicular, stellate.

8. Acrospeira. — Filaments creeping, ramuli branched,
the fertile terminating in a spiral coil of about three
joints, one of which swells into a rough-coated spore.

24

370 THE MICROSCOPIST.

9. Zygodesmus. — Filaments creeping, branched, with
short rarnuli bearing echinate spores, the pedicles with a
lateral indentation looking like a joint.

Order PHYSOMYCETES, or Mucoroidece (Moulds).—
Mycelium (microscopic) filamentous, bearing stalked sacs
(peridiola) containing numerous minute sporules.

Family I. ANTENNARIEI (doubtful). — Mycelium radiate
or erect, bearing sessile globular peridioles, filled with
ovate spores, discharged by rupture of sac at apex. Form
flocculent or byssoid patches on leaves or bark, and appear
to be merely states of other genera.

Family II. MUCORINI. — Mycelium filamentous, vague,
giving off erect simple or branched filaments terminating
in vesicular cells (peridioles) full of minute spores ; often
with central column in the interior. Form flocks and
clouds on decaying matters-

1. Phycomyces. — Peridiole pear-shaped, separated from
apex of pedicle by an even joint ; opening by an umbili-
cus. Spores oblong, large. Filaments tubular, continu-
ous, shining.

2. Hydrophora. — Peridiole subglobose, membranous, de-
hiscent, at first crystalline, aqueous, then turbid, and at
length indurated; bolumella absent; spores simple, con-
globated.

3. Mucor. — Peridiole subglobose, separating like a cap
(an annular fragment attached), from the erect, simple
pedicle, or bursting irregularly; columella cylindric or
ovate, spores simple.

4. Acrostalagmus (?). — Peridioles globose, with a colu-
mella; at the points of doubly- verticillate branches from
an erect pedicle.

5. JEgerita. — Peridiole spherical, very fugacious ; spori-
dia scattered like meal over the grumous receptacle.

APPENDIX. 371

6. Pilobolus. — Peridiole globular, separating like a cap
from the short stalk of a single cell, attached on a uni-
cellular ramified mycelium ; columella conical ; spores
numerous, free in the peridiole.

7. Syzygit.es. — Filaments erect, simple, branched above,
branches and branchlets di- or tri-chotomous, fertile
branches forcipate, bearing pairs of opposite internal cla-
vate branches which subsequently coalesce.

8. Eurotium. — Peridiole cellular, membranous, sessile,
at length bursting irregularly ; spores produced by a cen-
tral cellular nucleus, which breaks up into numerous pa-
rent cells (asci), in which four to eight minute spores are
formed, and finally set free ; filaments of mycelium ra-
diating from the base of the peridiole.

ALG^E— SEAWEEDS, ETC.

Order I. RHODOSPERMEJE or FLORIDE^E — Thal-
lus leaflike or filamentous, rose-red or purple. Fructifi-
cation consisting of: 1. Spores, mostly inclosed in concep-
tacles (ceramidia, coccidia, favellidia, etc.). 2. Tetraspores,
red or purple (a membranous sac containing, when ripe,
four spores). 3. Antheridia (pellucid sacs filled with
yellow corpuscles or spermatozoids).

Families I. RHODOMELACEJE. — Frond cellular, areolated
or articulated. Ceramidia external. Tetrapores in rows,
immersed in ramuli or contained in proper receptacles
(stichidia).

1. Odonthalia. — Frond flattened, linear, with obsolete
midrib, pinnatifid, alternately inciso-dentate.

0. dentata. — Color, wine-red.

2. Ehodomela. — Frond cylindric, inarticulate, opaque.
Tetraspores in podlike receptacles (stichidia).

R. lycopodioides. — Purplish-brown.
R. subfusca. — Brownish or reddish.

3. Bostrychia. — Frond cylindric, inarticulate, dotted.
The surface-cells quadrate. Tetraspores in terminal pods.

372 THE MICKOSCOPIST.

4 4. RytiphlcBa. — Frond cylindric, inarticulate, trans-
versely striate. Tetraspores in podlike receptacles.

5. Polysiphonia. — Frond cylindric, articulate in whole
or in part, the branches longitudinally striate. Tetraspores
in distorted ramuli.

6. Dasya. — Frond cylindric, the stem inarticulate, ra-
muli articulate, composed of a single string of cells. Te-
traspores in podlike receptacles (stichidia) borne by the
ramuli.

2. LAURENCIACE^. — Frond cellular, continuous. Cera-
midia external. Tetraspores scattered, immersed in the
branches and ramuli.

1. Bonnemaisonia. — Frond solid, filiform, rose-red.
Much branched ; branches margined with subulate dis-
tichous cilia.

2. Laurenda. — Frond solid, cylindric, or compressed
(purple or yellowish), pinnatifid. The ramuli blunt.

3. Chrysimenia. — Frond hollow, filled with mucus,
neither constricted nor chambered.

4. Chylodadia. — Branches hollow, filled with mucus,
constricted at intervals and chambered.

3. CORALLINACE^E. — Frond calcareous or crustaceous,
rigid. Ceramidia external, containing the tetraspores.

* Frond filiform, articulate.

1. Corallina. — Frond pinnated. Ceramidia terminal,
simple.

2. Jania. — Frond dichotomous. Ceramidia tipped with
two hornlike ramuli.

* * Frond crustaeeous or foliaceous, opaque, not articu-
late.

3. Melobesid. — Frond stony, forming a crustaceous ex-
pansion, or a foliaceous or shrublike body.

4. Hildebmndtia. — Frond cartilaginous, not stony.

APPENDIX. 373

* * * Frond plain, hyaline, composed of cells radiat-
ing from a centre. Fructification unknown.

5. Lithocystis (a minute parasite). — L. allmanni forms
minute white dots on Chrysimenia davelosa, consisting of
fanshaped fronds composed of square cells.

4. DELESSERICE^. — Frond cellular, continuous, areolated.
Coccidia external. Tctraspores collected into definite
clusters (sori).

1. Delesseria.- — Frond leafy, of definite form, with per-
current midrib.

2. Nitophyllum. — Frond leafy, of indefinite form. No
midrib (sometimes vague nerves).

3. Plocamium. — Frond linear or filiform, compressed.
Much branched, distichous, ramuli pectinate, secund.

5. RHODYMENIACE^:. — Frond cellular, continuous ; the
superficial cells minute. Coccidia external. Tetraspores
scattered through the frond or forming undefined, cloud-
like patches.

* Frond flat, expanded, leaflike, dichotomous or pal-
mate.

1. Stenogramme. — Conceptacles linear, riblike.

2. Hhodymenia. — Conceptacles hemispherical, scattered.

* * Frond compressed or terete, linear or filiform, much
branched.

3. Sphcerococcus. — Frond linear, compressed, two-edged,
distichously branched, with obscure midrib.

4. Gracilaria. — Frond filiform, compressed or flat, ir-
regularly branched ; the central cells very large.

5. Jdypnea. — Frond filiform, irregularly branched,
traversed by a fibro-cellular axis.

6. CRYPTONEMIACE.E. — Frond fibro-cellular, composed of
articulated fibres connected by gelatin. Favellidia im-
mersed in the frond or sub-external. Tetraspores immersed
in the frond.

374 THE MICROSCOPIST.

1. Sub-tribe COCCOARPEJE. — Frond solid, dense, cartilagi-
nous, or horny. Favellidia in semi-external tubercles or
swellings of frond.

1. Grateloupia. — Frond pinnate, flat, narrow, dense,
membrano-cartilaginous. Favellidia immersed in the
branches, communicating with the surface by a pore.
Tetraspores scattered.

2. Gelidium. — Frond pinnate, compressed, narrow,
horny. Favellidia immersed in swollen ramuli. Tetra-
spores forming subdefined sori in the ramuli.

3. Gigartina. — Frond cartilaginous, cylindric, or com-
pressed, its flesh composed of anastomosing filaments
lying apart in firm gelatin. Favellidia in external tuber-
cles. Tetraspores in dense sori sunk in the frond.

2. Sub-tribe SPONGIOCARPEJE.

4. Chondrus. — Frond fan-shaped, dichotomously cleft,
cartilaginous, dense. Tetraspores in sori immersed in sub-
stance of frond.

5. Phyllophora. — Frond stalked, rigid, membranaceous,
proliferous from the disk, dense. Tetraspores in distinct
superficial sori or in special leafletlike lobes.

6. Peyssonelia. — Frond depressed, expanded, rooting by
the under surface, concentrically zoned, membranous or
leathery. Tetraspores in superficial warts.

7. Gymnogongrus. — ^rondfiliform,dichotomous, horny,
of dense structure. Tetraspores strung together, contained
in superficial wartlike sori.

8. Polyides. — Root scutate. Frond cylindric, dichoto-
mous, cartilaginous. Favellce. in spongy external warts.
Tetraspores scattered in peripheric stratum of frond, cru-
ciate.

9. Furcellaria. — Root branching. Frond cylindric, di-
chotomous, cartilaginous. Favellce unknown. Tetraspores
imbedded among filaments of periphery, in swollen pod-
like upper branches of frond, transversely zoned.

3. Sub-tribe GASTROCARPE^I. — Frond gelatinously mem-

APPENDIX. 375

branous or fleshy, often of lax structure internally. Pavel-
lidia immersed in central substance of frond, very numerous.

10. Dumontia. — Frond cylindric, tubular, membranous.
Tufts of spores attached to wall of tube inside.

11. Halymenia. — Frond compressed or flat, gelatino-
membranaceous, surfaces separated by a few slender anas-
tomosing filaments. Masses of spores attached to inner
face of membranous wall.

12. Ginannia. — Frond cylindric, dichotomous, traversed
by a fibrous axis, walls membranous. Masses of spores
on inner face of wall.

13. Kallymenia. — Frond expanded, leaflike, fleshy-mem-
branous, solid, dense. Favellidia like pimples, half im-
mersed and scattered.

14. Iridea. — Frond expanded, leaflike, thick, fleshy-
leathery, solid, dense. Favellidia wholly immersed, densely
crowded.

15. Catanella. — Frond filiform, branched, constricted at
intervals into oblong articulations ; the tube filled with
lax filaments.

4. Sub-tribe GLOIOCLADIE^E. — Frond loosely gelatinous,
the filaments lying apart, surrounded by a copious gela-
tin. Favellidia immersed among filaments of periphery.

16. Cruoria. — Frond crustaceous, skinlike.

17. Naccaria. — Frond filiform, solid, cellular; ramuli
only composed of radiating free filaments.

18. Gloiosiphonia. — Frond tubular, hollow, walls com-
posed of radiating filaments.

19. Nemaleon. — Frond filiform, solid, elastic, filament-
ous, axis of a network of anastomosing filaments ; periph-
ery of moniliform free filaments.

20. Dudresnaia. — Frond filiform, solid, gelatinous, fila-
mentous, axis and periphery like the last.

21. Cronania. — Frond filiform, of a jointed filament,
whorled at the joints, with minute multifid, gelatinous
ramuli.

376 THE MICROSCOPIST.

7. CBRAMIACE^I. — Frond filiform, of an articulated fila-
ment, simple, or coated with stratum of small ceils. Fa-
vellce naked, berrylike masses. Tetraspores external or
partially immersed.

1. Ptilota. — Frond compressed, inarticulate, distichous,
pectinato-pinnate. Favellce pedunculate, involucrate.

2. Microcladia. — Frond filiform, inarticulate, dichoto-
mous. Favellce sessile, involucrate.

3. Ceramium. — Frond filiform, articulate, dichotomous ;
the joints opaque. Favellce sessile, mostly involucrate.
Tetraspores mostly immersed.

4. Spyridia. — Frond filiform, inarticulate ; the branches
clothed with minute, setiform, articulate ramelli. Favellce
pedunculate, involucrate. Tetraspores sessile on the ra-
melli.

5. Griffithsia. — Frond articulated, dichotomous, or
clothed with whorled, dichotomous ramelli, rose-red.
Favellce involucrate, sessile, or pedunculate. Tetraspores
sessile, or whorled ramelli.

6. Wrangelia. — Frond articulated, pinnate. Favellce
terminal, involucrate with tufts of pear-shaped spores.
Tetraspores sessile, scattered on the ramelli.

7. Seirospora. — Frond articulated. Tetraspores arranged
in terminal moniliform strings.

8. Callithamnion. — Frond, at least the branches and ra-
muli, articulate, mostly pinnated. Favellce terminal or
lateral, sessile without involucre (except in C. turneri).
Tetraspores sessile or pedicellate, scattered.

9. Trentepohlia. — Frond articulate, branched, cells in
single series. Favellce ? in terminal corymbs.

8. PORPHYRACEJE. — Frond plain and very thin, or tubu-
lar and filiform, purplish, with oval spores in sori and
tetraspores scattered over the frond.

1. Porphyra. — Frond plain, membranous, very thin,

APPENDIX. 377

purple ; oval spores in sori, and tetraspores (square) scat-
tered over frond.

2. Bangia. — Frond filiform, tubular, composed of radiat-
ing cells in transverse rows, in continuous hyaline sheath.

Order II. MELANOSPORE^E or FUCOIDEJE.— Ma-
rine. Thallus leaflike, or cordlike, or filamentous. Olive-
green or brown. Fructification varied. 1. In Fucaceee, mo-
noecious or dioecious conceptacles containing sporanges and
antheridia; the spores being fertilized by spermatozoids
after discharge of both from the parent. 2. In Lamina-
riacese, etc., of collections of clavate or filiform sporanges
producing zoospores, with antheridia-like Fucacese. 3. In
Cutleriacese similar. 4. In Dictyotacese three forms re-
sembling Floridese ; tetraspores, sporanges containing sim-
ple spores, and antheridia.

Family I. FUCACEJE. — Frond leathery or membranous,
cellular. Spores and antheridia together or separate in
spherical cavities imbedded in the frond.

* Air-vessels stalked.

1. Sarpassum. — Branches bearing ribbed leaves; air-
vessels simple.

2. Halidrys. — Frond linear, pinnate, leafless ; air-ves-
sels divided by transverse partitions.

* * Air-vessels immersed in substance of frond, or
absent.

3. Cytoseira. — Root scutate. Frond much branched,
bushy. Receptacles cellular.

4. Pycnophycus. — Root branching, Frond cy \mdr\Q. Re-
ceptacles cellular.

5. Fucus. — Root scutate. Frond dichotomous. Recep-
tacles filled with mucus, traversed by jointed threads.

6. Himanthalia. — Root scutate. Frond cup-shaped. Re-
ceptacles (frondlike) long, strap-shaped, dichoraotously
branched.

378 THE MICROSCOPIST.

3. DICTYOTACEJE. — Frond cellular, flat, compact. Spores,
antheridia (and tetraspores T) in spots or lines (sori) on sur-
face.

1. Haliseris. — Frond dichotomous with midrib.

2. Padina. — Frond ribless, fan-shaped, concentrically
streaked. Sori linear, concentric, bursting through the
epiderm.

3. Zonaria. — Frond ribless, lobed, concentrically striate.
Sori roundish, with spores and jointed threads.

4. Taonia. — Frond ribless, 'cleft irregularly, somewhat
fan-shaped. Sori linear, concentric, superficial, alternating
with scattered spores.

5. Dictyota. — Frond ribless^ dichotomous. Sori round-
ish, scattered, bursting through epiderm, or (on distinct
individuals) scattered spores.

3. CUTLERIACEJL — Frond cellular, compact, ribless.
Dotlike collections of sporanges divided into eight com-
partments, and antheridia (?) consisting of chambered fila-
ments in groups of curved jointed hairs.

1. Cutleria.

4. LAMINARIACE^:. — Frond leathery or gelatinous, cellu-
lar. Unilocidar sporanges in cloudlike patches, or cover-
ing the whole surface of frond ; or multilocular sporanges
clothing the whole surface of the frond like an epidermis.

* Frond stalked, the stalk ending in an expanded leaf-
like portion.

1. Alaria. — Leaf membranous, with cartilaginous per-
current midrib.

2. Laminaria. — Leaf (simple or cleft) without any
midrib.

* * Frond simple, leafless.

3. Chorda.— Frond cylindric, hollow, the cavity having
transverse partitions.

APPENDIX. 379

5. DICHTYOSIPHONACE.E. — Frond cylindric, branched,
filamentous in structure. Ovoid sporanges imbedded
lengthwise in substance of frond, opening by a pore on
the surface.

1. Dictyosiphon. — Root a minute naked disk. Frond
cylindric, branched. Oosporanges irregularly scattered,
solitary or in dotlike sori.

2. Striaria Oosporanges in transverse lines on surface of
frond.

6. PUNCTARIACEJE. — Frond cylindric or flat, unbranched,
cellular. Ovate sporanges in groups on the surface, inter-
mixed with clavate filaments (paraphyses}.

1. Punctaria. — Frond flat and leaflike. Sporanges scat-
tered or in sori.

2. Asperococcus. — Frond membranous, tubular, cylin-
dric, or compressed. Sporanges in dotlike sori.

3. Litosiphon. — Frond cartilaginous, filiform, subsolid.
Sporanges scattered, almost solitary.

7. SPOROCHNACE.E. — Frond leathery or membranous,
cellular, branched. Unilocular or multilocur sporanges at-
tached to external jointed filaments, free or collected in
knoblike masses.

* Sporanges on pencilled filaments issuing from the
branches (Arthrocladiese).

1. Demarestia. — Frond solid or flat, dichotomously
branched.

2. Arlhrocladia. — Frond traversed by a jointed tube,
filiform, nodose.

3. Stilophora. — Frond filiform, tubular or solid, branched.
Sporanges from necklace-shaped filaments in wartlike
groups on the frond.

* *• Sporanges in knoblike receptacles composed of
whorled filaments (Sporochnese).

4. Sporochnus. — Receptacles lateral on short peduncles.

380 THE MICROSCOPIST.

5. Carpomitra. — Receptacles terminal, at tips of the
branches.

8. CHORDARIACE.E. — Frond cartilaginous or gelatinous,
of horizontal and vertical filaments (jointed) interlaced.
Unilocular sporanges from the base of the vertical fila-
ments forming the epiderm of the frond, and multilocular
sporanges developed later from filaments surrounding the
former.

1. Chordaria. — Axis cartilaginous, dense, filaments of
circumference unbranched.

2. Mesogloia. — Axis gelatinous, loose, filaments of cir-
cumference branching.

9. MYRIONEMACE.E. — Frond tubelike, crustaceous or
spreading as a crust, of filamentous structure. Unilocu-
lar and multilocular sporanges attached to the superficial
filaments and concealed among them.

1. Leathesia. — Frond tuber-shaped.

2. Ralfsia. — Frond crustaceous.

3. Elachistea. Frond parasitic, of a tubular base, bear-
ing pencilled erect filaments.

4. Myrionema. — Frond parasitic, forming a flat base,
bearing cushionlike tufts of decumbent filaments.

10. ECTOCARPACE^I. — Frond filiform, jointed. Unilocu-
lar sporanges, ovate sacs at ends or intermediate joints of
the filaments and multilocular sporanges of minute jointed
filaments in similar situations. Antheridia with spermato-
zoids in Sphacelaria.

* Frond rigid, each articulation of numerous cells
(Sphacelariece).

1. Cladostephus. — Ramuli whorl ed.

2. Sphacelaria. — Ramuli distichous, primated.

* * Frond flaccid, each articulation of a single cell.

3. Ectocarpus. — Frond branching, ramuli scattered.

APPENDIX. 381

4. Myriotrichia. — Frond unbranched, ramuli whorled,
tipped with pellucid fibres.

Order III. CHLOROSPOKE^E or CONFERVOIDE^E.
— In sea or fresh water, or on damp surfaces, with fila-
mentous, or more rarely a leaflike thallus; microscopic
forms, sometimes pulverulent or gelatinous, consisting fre-
quently of definitely arranged groups of distinct cells,
with an ordinary structure, or with their membrane silici-
fied (Diatomacese). Fructification varied.

1. Resting spores produced from cell-contents after fer-
tilization either by conjugation or impregnation.

2. Spermatozoids produced from the contents of other
cells.

3. Zoospores. — Two, four or multiciliated active gonidia,
discharged from the vegetative cells without impregna-
tion and germinating directly.

The simple vegetative increase of unicellular forms is
analogous to cell division of filamentous forms.

The Yolvocinese pass the vegetative stage of existence
as ciliated zoospores collected within a gelatinous com-
mon envelope.

Family I. LEMANEJE. — Frond cartilaginous, leathery,
inarticulate, filamentous, hollow, with whorls of warts
at irregular distances, or necklace-shaped. Fructification
tufted, simple, or branched ; necklace-shaped filaments, at-
tached to inner surface of tubular frond, and breaking up
into elliptic spores. Grow* in fresh water.

1. Lemania. — Two species, L. torulosa and L.fluwatilis,
in clear running streams.

2. BATRACHOSPERMEJE. — Plants filamentous, articulated,
invested with gelatin. Frond of aggregated, articulate,
longitudinal cells, whorled at intervals, with short, hori-
zontal, cylindric, or beaded, jointed ramuli. Fructification

382 THE MICROSCOPIST.

ovate spores, and tufts of antheridial cells (?) attached to
the lateral ramuli, which consist of minute, radiating,
dichotomous, beaded filaments. Fresh-water plants.

1. Batrachospermum. — Lateral whorled ramuli, beaded
spores in globular knobs in the whorls.

1. B. moniliform. — Color various, vaguely branched.

2. B. giganteum. — Large, purple when dry, long, bifur-
cated branches.

3. B. affine.

4. B. coerulescens. — ^Eruginous, slender, branched.
Upper and lower whorls confluent.

5. B. vagum. — Dichotomously branched, equally thick
throughout ; whorls all confluent.

2. Thorea. — Stems continuous, whorled, articulated,
sometimes branched, ramuli cylindric, the spores at their

3. CH^ETOPHORACE^:. — In the sea or fresh water, coated
by gelatinous substance, either filiform or (connected fila-
ments) gelatinous, definitely formed or shapeless fronds
or masses. Filaments jointed, bearing bristlelike pro-
cesses. Fructification, zoospores from cell-contents of fila-
ments, resting spores from particular cells after impregna-
tion by ciliated spermatozoids produced in antheridial cells.

1. Draparnaldia. — Filaments free, primary nearly color-
less, with tufts of colored ramuli at the joints ; zoospores
formed singly in the joints of the ramuli.

2. Ch&tophora. — Filaments dichotomously branched,
aggregated into shapeless, incrusted or branched, gelati-
nous fronds, the joints bearing bristlelike branches.
Zoospores (four cilia) solitary in the articulations, mem-
branes of filaments very fugacious. (Little green protu-
berances on sticks, etc., in fresh water.)

C. endivicefolia. C. tuberculosa. C. elegans. C. pisiformis.
C. dilatata. C. longceva.

3. Coleoch(Ete. — Frond disk-shaped or irregularly ex-

APPENDIX. 383

panded, adherent to leaves, etc., of aquatic plants, formed
of jointed dichotornous filaments radiating from a centre,
more or less conjointed laterally, joints producing from
the back a slender truncate open tube from which a long
bristle is exserted. Spores and zoospores formed in the
joints.

4. Ocklochcete. — Frond discoid, appressed, filaments cyl-
indric, radiating, irregularly branched, of a single series
of cells, each of which is prolonged above into an inar-
ticulate bristle. 0. hystrix.

4. CONFERVACE^E. — In sea or fresh water, filamentous,
jointed, without evident gelatin. Filaments variable, sim-
ple or branched, cells more or less filled with green, or
rarely brown or purple, granular matter, sometimes ar-
ranged in peculiar patterns on the walls, and convertible
into spores or zoospores. Not conjugating.

1. Cladophora. — Filaments tufted, much branched. Sea
and fresh water. Zoospores minute, many in a cell.

C. cepagropila. — Dense balls in lakes, etc.
C. crispata. — Yellowish or dull-green strata.

2. Rhizoclonium. — Filaments decumbent, with small
rootlike branches. Zoospores minute, numerous. Sea,
brackish, and fresh water.

R. rivulare. — Filaments simple. Bright-green bundles,
two to three feet long, in streams.
JR. tortuosum. — In salt-water pools.
jR. arenosum. — Dirty-green strata, on sandy seashores.
R. obtusangulum. — Sandy, seashores.
R. riparium.

R. implexum. — On mountain rocks.
jR. arenicolum (ditto).

3. Conferva. — Filaments unbranched. Zoospores minute,
numerous in the cells. Sea, brackish, and fresh water.

C. bombycina. — Yellow-green cloudy stratum in stagnant
water.

384 THE MICROSCOPIST.

C.floccosa. — More robust, articulations once or twice
longer than broad.

C. cerea. — Yellow-green tufted filaments, thick as hog's
bristles.

C. melagonium. — Erect tufted filaments.

C. linum. — Long, tangled filaments.

4. Ulothrix (?). — Filaments simple, often fasciculated,
joints short. Zoospores four ciliated ; two, four, or more
in a cell. Fresh water.

5. Stigeodonium (?). — Filaments branched, ramules run-
ning out into slender points, cell-walls often dissolving to
emit zoospores. Zoospores four ciliated, one in a cell.

5. ZYGNEMACE.E. — Fresh-water filaments, no evident
gelatin, of a series of cylindric cells, straight or curved.
Cell-contents often arranged in elegant patterns on the
walls. Reproduction from conjugation followed by a true
spore, in some genera dividing into four sporules.

1. Zygnema. — Filaments simple, green contents ar-
ranged in two globular or stellate masses in each cell.
Conjugate by transverse processes. Spores in a parent
cell on cross branch.

* Spores in one of parent cells.
Z. cruciata. — Spores globose.

Z. stagnalis.
Z. insignis.
Z. bicornis.

* * Spores in cross branches.
Z. immersa.

Z. conspicaa.
Z. decussata.
Z. RalfsiL
Z. pectinata.

2. Spirogyra. — Filaments simple, green contents in one
or more spiral bands on cell-wall. Conjugate by trans-

APPENDIX. 385

verse processes. Spores in one of parent- cells (or occa-
sionally in both).

* Spiral band single.

8. tenuissima. S. longata. 8. inflata. S. communis. 8.
quinina.

* * Spirals two.

S. decemina. 8. elowgata.

* * * Spirals numerous.

S. nitida. 8. maxima. 8. bellis. 8. pellucida. 8. rivu-
laris. 8. curvaia.

3. Zygogonium. — Filaments simple or slightly branched ;
contents diffused or in two transverse bands. Conjugate
by transverse processes. Spores globose, in cross branches,
or in blind lateral pouches without conjugation. Z.
ericetorum.

4. Mesocarpus. — Filaments simple, with contents dif-
fused. Conjugate by transverse processes, from which the
filaments become recurved. Spores in cross branches.

M. scalaris. M. depressus.

5. Staurocarpus. — Filaments simple, contents diffused
(rarely in moniliforrn lines). Conjugate by transverse pro-
cesses, from which the filaments become recurved. Spores
(or sporanges) square or cruciate in dilated cross branches.

8. glutinosus. 8. ccerulescens. 8. quadratus. S. virescens.
8. gracillimus. 8. gradlis.

6. Mougeotia. — Filaments simple, soon bent at intervals ;
contents mostly diffused, sometimes in several serpentine
lines. Conjugate by the inosculation of filaments at the
convexity of the angles. Spores not known. M. genuflexa.

6. (EDOGONIACE^E. — Simple or branched, fresh-water
filamentous plants, attached, without gelatin. Cell-con-
tents uniform, dense. Cell-division accompanied by cir-
cumcissile dehiscence of parent-cell, producing rings on
the filaments. Reproduction by zoospores from contents
of a cell, with a crown of cilia ; resting spores in sporan-

25

386 THE MICROSCOPIST.

gial cells after fecundation by ciliated spermatozoids
formed in antberidial cells.

1. (Edogonium. — Filaments unbranched.

* Spores globular.

f Sporanges with valvular lid.
(E. rostellatum. — Monoecious,
f f Sporanges witb lateral orifice.
£ Monoecious.

(E. curvun. (E. tumidulum.
$ % Gynandrosporous.

(E. Rothii. (E. depressum. (E. Braunii. (E. eckino-
spermum,.

* * Spores oval.

f Sporanges witb valvular lid.

^ Gynandrosporous.

(E. dliatum.

f f Sporanges witb lateral orifice.

^ Gynandrosporous.

(E. apophysatum.

$ :f Dioecious.

(E. gemelliparum.

2. Bulbochceta. — Filaments brancbed and bearing bristle-
cells witb a bulbous base.

7. SIPHONACE.E.— Sea, fresb water, or on damp ground.
Membranous or borny hyaline substance, filled with green
(in Saprolegniese colorless) granular matter. Fronds con-
tinuous tubular filaments, free, or in spongy masses of
various shapes, crustaceous, globular, cylindric, or flat.
Zoospores single or numerous. Resting spores in spor-
angial cells after impregnation by contents of antheridial
cells of different form.

1. Codium. — Filaments green, branched, interwoven into
spongiform frond, producing biciliated zoospores in spor-
angial cells borne on the sides of the erect clavate branches.
Marine.

APPENDIX. 387

2. B'yopsis. — Filamentsgreen, free,primately branched ;
two or four ciliated zoospores in extremities of branches.
Marine. 1$. plumosa. B. hypnoides.

3. Vaucheria. — Filaments green, more or less branched,
continuous, producing in apices large solitary zoospores
covered with cilia, also bearing lateral, globose, sporangial
cells and hooklike antheridial cells (" horns "). Marine
or aquatic or on damp ground.

4. Botrydium. — Frond a spherical green vesicle on a
ramified filamentous base, the cavity of the whole con-
tinuous, the ramified base producing new vesicles (spor-
anges) by stoloniferous growth. Multiplied by granular
contents of vesicle discharged by rupture at the summit.
Damp grounds.

5. Hydrodictyon. — Frond a green baglike net, with
usually pentagonal open meshes, formed of cylindric cells
connected by their ends. Ciliated zoospores formed in
the " link "-cells, uniting and forming a miniature net be-
fore escaping from parent-cell.

6. Achyla. — Filaments colorless or light brownish (like
mycelia of fungi) ; free, slightly branched. Numerous
zoospores in apices of filaments, and spores in globose
lateral sporangial cells. On dead flies, fishes, or sometimes
on decaying vegetable matter in water. A. prolifera.

8. OSCILLATORIACE.E. — Sea, fresh water, or damp ground.
Gelatinous and filamentous. Filaments slender, tubular,
continuous, filled with colored, granular, transversely
striate substance, seldom branched, though often coher-
ing so as to appear branched ; usually massed in broad
floating or sessile strata ; very gelatinous ; occasionally
erect and tufted. More rarely in radiating series bound
by firm gelatin, and then forming globose, lobed, or flat
crustaceous fronds. Contents separate into roundish or
lenticular gonidia.

* In fresh water or damp earth.

388 THE MICROSCOPIST.

a. Stratum ceruginous or blue-green.

0. limosa. 0. tenius. 0. muscorum. 0. turfosa. 0.
decor ticans.

b. Stratum dull green inclining to purple, black, or
brown.

0. nigra. 0. autumnalis. 0. cortexta. 0. ochracea.
* * Marine or in brackish water.

0. littoralis.

The above are species of Oscillatoria.

A. OSCILLATORIE^E. — Filaments transversely striate or
moniliform, sometimes spirally curled, sheathed, or in the
minute forms without evident sheaths. Spontaneous
oscillating, creeping, or serpentine motion. Increase by
transverse division.

1. Bacterium. — Filaments colorless, very small, short,
wand-shaped, or longish-oval, with two to four cross
striae, exhibiting vibratory motion.

2. Vibrio. — Filaments colorless, very slender, monili-
form. Active serpentine motion.

3. Spirulina. — Filaments green, very slender, continu-
ous or moniliform, curled into a long helical or screw
form ; oscillating.

4. Didymohdix. — Filaments brown, very slender, con-
tinuous, curled spirally and twisted in pairs.

5. Oscillatoria. — Filaments colored, continuous, trans-
versely striated, readily breaking across ; a proper cellu-
lar sheath ; oscillating ; in strata imbedded in gelatin.

6. Microcoleus. — Filaments as in 5, but in bundles in a
common gelatinous sheath, tubular and dichotomously
branched. Filaments oscillating.

7. Cwnocoleus. — Filaments branched, contained in a
tough, more or less permanent sheath, which bursts ir-
regularly. Filaments annulated.

8. Symploca. — Filaments as in 5, but erect and tufted,
coherent at base, bristling above.

APPENDIX. 389

B. LYNGBYE.E. — Filaments motionless (?), oscillarioid,
inclosed in distinct sheath, tufted or forming strata, with
or without enveloping jelly.

9. Dasygloea. — Filaments unbranched. Older sheaths
broad, coalescent outside in amorphous gelatinous stratum.

10. Lyngbya. — Filaments elongated, articulated, un-
branched ; distinct convoluted cellulose tube ; no gelatin-
ous matrix ; articulations close.

11. Leibleinia. — Filaments short, erect, tufted, un-
branched ; distinct cellulose coat ; free ; no jelly.

C. SCYTONEME^;. — Filaments articulated, simple, or
branched, motionless ; distinct articulations and large in-
terstitial (propagative?) cells; sheaths soften and swell,
but no gelatinous matrix.

12. Scytonema. — Filaments ceespitose, or, more rarely,
fasciculate; a double (lamellar) gelatinous sheath, mostly
closed at apex ; branches continuous by lateral growing
out of primary filaments, with kneelike base.

13. Desmonema. — Filaments branched, more or less co-
herent ; primary branches with connecting cell at base ;
secondary branches without cell, annulated.

14. Arthronema. — Filaments articulated, simple, in short
lengths, overlapping at their ends in gelatinous sheath.

15. Petalonema. — Filaments branched; outer sheaths of
joints expanded upwards and outwards into funnel-shaped
bodies, each partly overlapping its successor, forming a
common obliquely lamellated and transversely barred
gelatinous cylinder.

16. Calothrix. — Filaments closely articulated, tufted,
with branches in apposition for some distance, here and
there cohering laterally; sheaths firm, often dark-colored.

17. Tolypothrix. — Filaments free, radiantly or fastigi-
ately branched, distinctly articulated at bases of branches,
which are continuous by ex-current, not in apposition ;
sheaths thin, hyaline.

390 THE MICROSCOPIST.

18. Sirosiphon. — Filaments single, double, or triple, in
distinct common sheath, articulated, branched by lateral
budding ; branches divergent.

19. Sehizothrix. — Filaments branched by division ;
sheaths lamellated, thick, rigid, curled, thickened below,
finally longitudinally divided.

20. Sympkyosipkon. — Filaments erect or ascending, in-
closed in lamellated hard sheaths, concreted laterally at
their bases, involved in jelly.

21. Rhizonema. — Sheath cellular, with branched and
anastomosing rootlets (?) ; filaments annulated, inter-
rupted here and there by a connecting cell ; branches in
pairs from protrusion of filament.

D. RIVULARIE^E. — Filaments articulated ; enlarged basal
cell, attenuated above, connected into definite or indefinite
fronds ; motionless.

22. Schizosiphon. — Basal cells globose; filaments simple,
sheathed; sheaths in groups, dark-colored, hard, open,
and expanded above, and overlapping so as to form a
succession of ochrese, which have the free borders slit up
into filaments or fringes; also displaying a spiral struc-
ture in dissolution.

23 . Physactis. — Filaments whip-shaped, torulose at base ;
sheaths simple, gelatinous, in a globose and solid, or sub-
sequently a bullose, vesicular frond ; in globose fronds
filaments radiate from centre, in vesicular from internal
(lower) surface of gelatinous matrix.

24. Ainactis. — Filaments branched, articulate ; thin
sheaths in solid pulvinate frond, which is concentrically
zoned by the dichotomous branching of filaments ; sheaths
more or less solidified by carbonate of lime ; sometimes a
spiral structure in dissolution.

25. Rivularia. — Filaments with an oval basal cell, suc-
ceeded by a cylindric manubrium, the remainder short,
attenuated upwards (whip-shaped) ; sheaths sometimes

APPENDIX. 391

saccate below, open (not fringed) above, forming a slippery
gelatinous frond.

26. Euactis. — Filaments whip-shaped, with repeated
ochreate sheaths, forming fronds in which they radiate,
and by superposition of successive generations form con-
centric layers ; the ochreate sheaths are cartilaginous,
lamellated, united laterally, funnel-shaped, fringed at open
edge.

27. Inomeria. — Filaments whip-shaped, vertical, paral-
lel ; obscure sheaths decomposed into slender filaments,
forming crustaceous fronds, becoming stony.

28. Petronema. — Densely csespitose, erect, somewhat
regularly branched ; branches free, with obtuse rounded
apices, and each with connecting cell at base ; filaments
annulated and growing thicker upwards.

E. LEPTOTHRICE.E. — Doubtful Oscillatoriacese.

29. Leptothrix. — Filaments very slender, neither articu-
lated, branched, concreted, nor sheathed.

30. Hypheothrix. — Filaments unbranched, inarticulate,
sheathed, interwoven in more or less compact stratum.

31. Symploca. — Filaments unbranched, sheathed, inar-
ticulate, concreted into branches, conjoined at their bases;
sheath a simple hyaline membrane.

9. NOSTOCHACE,B. — Gelatinous Fresh water, or in damp
mosses, etc. ; soft, or almost leathery, of variously curled
or twisted necklace-shaped filaments, colorless or green,
composed of simple (or double) rows of cells, contained in
a gelatinous matrix of definite form, or heaped without
order in a gelatinous mass. Some cells enlarge and form
vesicular empty cells or sporangial cells ; reproduce by
breaking up the filaments, and, by resting spores formed
singly in the sporanges.

1. Nostoc. — Phycoma, or general mass of plant in a film
formed by condensation of the surface ; globose, or spread

392 THE MICROSCOPIST.

out ; form variable, gelatinous or mucous, coriaceous, soft
or hard, elastic, slimy, containing simple, curved, and en-
tangled moniliform colorless or greenish filaments, com-
posed of cells, which seem solid, imbedded in amorphous
gelatinous matrix ; heterocysts globose, interstitial, larger
than ordinary joints of filaments.

N. commune. N. cceruleum. N. verruconum. N. minat-
issimum. N. lichenoides. N. vesicarium. N. sphcericum.
N. pruniforme. N.foliacum.

2. Monormia. — Frond or phycoma definite, gelatinous,
elongated, linear; spirally curled and convoluted sheath,
inclosing a single moniliform filament ; heterocysts inter-
stitial; sporanges from joints most distant from vesicular
cells. M. intricata.

3. Anabaina. — Filaments moniliform or cylindric, often
curled, in formless mucous matrix, often forming a float-
ing film, with vesicular cells (heterocysts) and sporangial
cells.

* Without a membranous sheath.

a. Trichormus. — Heterocysts interstitial and terminal ;
sporanges first from cells most distant from heterocysts.

b. Sphazrozyga. — Heterocysts interstitial ; sporanges
from nearest cells.

c. Cylindrospermum. — Heterocysts terminal ; sporanges
as last.

d. Dolichospermum. — Heterocysts interstitial ; sporanges
indefinite and unequal.

* * Filaments not included in membranous sheath.

e. Aphanizomenon. — Heterocysts none (?) ; sporanges
usually simple and unequal.

f. Sperm.osira. — Heterocysts interstitial, single or in
pairs ; sporanges as in Trichormus.

10. ULVACE^E. — Marine or fresh-water Algse, membra-
nous, flat, and expanded ; tubular or saccate fronds, com-
posed of polygonal cells firmly conjoined by their sides ;

APPENDIX. 393

zoospores formed from cell-contents and breaking out from
the surface, or motionless spores from the whole contents
of a cell.

1. Ulva. — Frond plane, simple, or lobed, of double layer
of cells, closely packed, producing zoospores. U. lactuca.
(latissima) U. Linza.

2. Enter omorpha. — Frond hollow, simple, or branched,
of a single layer of cells, closely packed, forming a sac or
tube, with zoospores. E. intestinalis.

3. Monostroma. — Frond flat or saccate, simple or lacer-
ate-lobed, forming a single layer of cells, which are scat-
tered in a homogeneous membrane, with zoospores. M.
buUosum.

4. Prasiola. — Frond membranous, lacerate-lobed, of sin-
gle layer of cells in simple or compound lines, or groups
multiple of four ; spores from whole contents of cells, mo-
tionless. P. callophylla, crispa, furfur acea, and stipitata.

5. Schizogonium. — Frond filiform, dilated here and there
into flat ribands, with two or four rows of cells ; spores
from whole contents, motionless. 8. percursum. S. Icete-
vireus. S. murale.

11. PALMELLACE^E. — Plants forming gelatinous or pul-
verulent crusts on damp surfaces of stone, wood, etc.
Masses of gelatinous substance, or pseudo-membranous
expansions or fronds, of flat, globular, or tubular form, of
one or numerous cells, with green, red, or yellowish con-
tents ; spherical or elliptical form, the simplest being iso-
lated cells (in groups of two, four, eight, etc.) ; others
formed of some multiple of four, the highest of compact,
numerous, more or less closely conjoined cells. Reproduce
by cell-division, by conversion of cell-contents into zoo-
spores, and, by resting spores formed sometimes after
conjugation, in other cases probably after fecundation by
spermatozoids.

394 THE MICROSCOPIST.

* Plants with a frond of colorless gelatinous substance.
f Frond amorphous.

1. Palmella. — Frond a slimy stratum, crowded with
large globular cells, multiplying by division ; green and
red. P. cruenta.

2. Microhaloa. — Frond mucoid, floating in water,
crowded with minute cells, multiplying by division ;
green and red.

f f Frond definite.

3. Glceocarpus. — Frond of cells in wide gelatinous coats,
inclosed in similar coats of parent-cells for several genera-
tions.

4. Botrydina. — Frond globose, the periphery of cells co-
hering into a sort of cellular epiderm, the inner cells free.

5. Clathrocystis. — Frond gelatinous, first globose, then
hollow, then broken by irregular expansion into a coarse
net, finally breaking up; frond crowded with minute cells,
multiplied by division.

6. Coccochloris. — Frond globose, gelatinous, containing
numerous distinct cells, all free.

7. Merismopoedia. — Frond very minute, flat, square, ge-
latinous ; cells in families of four, sixteen, and sixty-four.

8. Urococcas. — Frond of streaked gelatinous tubes,
formed of ensheathing parent-cell membrane in a single
row, with cells solitary or byinary (from division) in ends
of the tubes.

9. Hormospora. — Frond a wide, gelatinous, simple, or
branched sheath, with* single row of cells in twos or fours.

10. Tetraspora. — Frond gelatinous, more or less foliace-
ous ; cells in fours, ultimately becoming free as zoospores.

11. Hydrurus. — Frond toughly gelatinous, filiform, with
imbedded longitudinal rows of cells.

12. Palmodictyon. — Frond gelatinous, filiform, branched ;
branches dividing and anastomosing into a net, consisting
of large vesicular cells with colored contents, which escape
as zoospores.

APPENDIX. 395

* * Plants of single cells, solitary, or united in small
numbers into families. (Unicellular Algse.)
f Solitary cells.

13. Schizochlamys. — Cells free, globular, aggregated in
jelly, each dividing into two or four, set free by parent-
cell breaking into two or four segments ; green.

14. Chlorospkcera. — Unicellular, free; a large globose
cell with green contents, dividing into two, in each of
which is formed a new cell like the parent, set free by
lateral rupture of parent-cell membranes.

15. Charadum. — Unicellular ; a minute, attached, pyri-
form, fusiform, or subglobose sac, shortly stipitate, con-
taining green protoplasm, which by oft-repeated binary
division forms a swarm of active two-ciliated zoospores,
escaping by a lateral or terminal slit.

16. Apiocystis. — Simple attached sac with stout mem-
brane ; green contents ; at first groups of four still go-
nidia, which subdivide repeatedly, and as the parent-sac
grows become active zoospores, which move in parent-sac,
and then break out in a swarm.

17. Codiolum. — Attached, small, long, clavate sac, at-
tenuated below into a solid stipe, tilled with granular
green contents and starch granules, ultimately converted
at once into many gonidia, escaping by rupture of apex ;
gonidia globose.

18. Jrlydrocytium. — Attached minute oblong sac ; short
hyaline stalk ; green contents ; parietal starch-corpuscle ;
contents divided at once into many two-ciliated zoospores,
lying on the wall, then moving actively and breaking out
into a swarm.

19. Ophiocytium. — Minute, elongated, cylindric, curved
sac ; short stipe ; free or attached ; green contents scat-
tered ; finally eight gonidia in a single row, set free by
circumcissile rupture of end of sac.

20. Sciadium. — First a minute, solitary, attached, elon-
gate, tubular, stipitate sac, with eight gonidia in single

396 THE MICROSCOPIST.

row ; apex of sac opens by circumcision, and the gonidia
grow out into tubes like the parent in an umbel, their
stipes remaining inserted ; each new tube repeats this to
fourth or more generation, the last generation from the
compound umbel emitting its gonidia as two-ciliated zoo-
spores.

21. Chytridium. — Parasitic ; minute globular pyriform
or urceolate sac, attached by a foot which penetrates into
the supporting body (mostly a Confervoid) ; cell-contents
colorless, becoming two-ciliated zoospores, escaping by
dehiscence of a valvelike lid, or by simple rupture of sac.

22. Pythium. — Parasitic ; a globular sac in the interior
of cell of diseased Confervoids, often in groups ; contents
colorless ; sac grows to flasklike form, the neck perforat-
ing the wall of the nurse-plant and bursting to emit ac-
tive gonidia (?).

12. VOLVOCINE^E. — Microscopic, cellular; fresh-water
groups of bodies, like zoospores, connected into four by
enveloping membranes ; either assemblages of coated zoo-
spores by cohering membranes, or of naked zoospores in
a common membrane; the zoospore-like two-ciliated bodies
perforate the coat, and by conjoined action move the entire
group; reproduce by division (Gonium)^ or by single cells
becoming families (Pandorina, Volvoz), and, by resting
spores, formed after impregnation of some cells by sperma-
tozoids formed from contents of other cells.

Solitary :

No cilia, Gyges.

A pair of cilia, PROTOCOCCUS.

Grouped :

Square layer, gonidia of 2 cilia, GONIUM.

APPENDIX. 397

Forming a spherical body :
Cilium solitary.
With a tail, Uroglena.
Without a tail.
Without eye-spot.
With special coats, Syncrypta.
With eye-spot.

Gonidia dividing into clusters, Spharosira.
Cilia 2.

No eye-spot, Synura.
With eye-spot.
Common envelope spherical.
Gonidia numerous, all over periphery, VOL vox.
Gonidia 8, in a circle at the equator, STEPHANOSPH^RA.
Envelope ellipsoidal, gonidia 16 or 32, perhaps stages
of Volvox or Pandorina.

13. DESMIDIACE^;. — Microscopic, gelatinous, green; cells
without siliceous coat; forms varied, as oval, crescentic,
cylindric, etc., with a more or less stellate appearance,
having a bilateral symmetry, the junction being marked
by a division of the green contents ; individual cells free
or grouped. Reproduction by division and by resting
spores produced in sporangia formed after conjugation of
two cells and union of their contents, and by zoospores
formed in the vegetative cells or in the germinating rest-
ing spores.

I. CLOSTERIEJE. — Cells single, elongated, never spinous,
often not constricted in the middle ; sporangia smooth.

1. Closterium. — Cell crescent-shaped, or much attenu-
ated at the ends, not constricted in the middle.

2. Penium. — Cell straight, not, or very little constricted
in the middle, rounded at both ends.

3. Tetmemorus. — Cell straight, constricted, notched at
ends.

398 THE MICROSCOPIST.

4. Doddium. — Cell straight, constricted, truncate at
ends.

5. Spirotcenia. — Cell straight, not constricted ; endo-
chrome spiral.

IT. COSMARIEJE. — Cells single, distinctly constricted in

O ' »/

the middle ; segments seldom longer than broad ; sporan-
gia spinous or tuberculated.

6. Micrasterias. — Lobes of the segments incised or bi-
dentate.

7. Euastrum. — Segments sinuated, generally notched at
ends, and with inflated protuberances.

8. Cosmarium. — Segments neither notched nor sinuated,
end view elliptic, circular, or cruciform.

9. Xanthulium. — Segments compressed, entire, spinous.

10. Arthrodesmus. — Segments compressed, each with
only two spines.

11. Stturastrum. — End view angular, radiate, or with
elongated processes which are never in pairs.

12. Didymocladon. — End view angular, each angle with
two processes, one inferior and parallel with that of other
segment, the other superior and divergent.

III. DESMIDIE.E. — Cells united into an elongated jointed
filament ; sporangia spherical, smooth.

13. Hyalotheca. — Filament cylindric.

14. Didymoprium. — Filament cylindric or subcylindric ;
cells with two opposite bidentate projections.

15. Desmidium. — Filament triangular or quadrangular ;
cells with two opposite bidentate projections.

16. Aptogonum. — Filament triangular or plane, with
foramina between the joints.

17. Sphcerozosma. — Filament plane ; margins incised or
sinuate ; joints with junction glands.

APPENDIX. 399

IY. ANKISTRODESMI^E. — Cells elongate, entire, small,
grouped in fagot-like bundles.

18. Ankistrodesmus.

Y. PEDIASTRE.E. — Cells grouped in the form of a disk
or star, or placed side by side in one or two short rows.

19. Pediastrum. — Cells forming a disk or star, marginal
cells bidentate.

20. Monactinus. — Cells as in 19, but marginal cells uni-
dentate.

21. Scenedesmus. — Cells placed side by side in one or
two rows.

14. DIATOMACEJE. — For genera, see page 142.

INDEX AND GLOSSAEY

OF TEEMS USED IN THE MICROSCOPIC SCIENCES.

The figures refer to the page.

Aberration, 22 (Lat. ab, from, and erro, to wander). — Errors
resulting from imperfection of lenses.

Aberrant. — Differing from customary structure.

Abnormal (Lat. ab, and norma, a rule). — Contrary to usual
structure.

Abiogenesis, 125 (Gr. a, privative ; bios, life; and gennao, to
produce). — Spontaneous generation, or production without pre-
existing life.

Absorption Bands, 18, 45, 101. — Lines, more or less distinct,
produced in the spectrum by certain transparent substances.

Abranchiate (Gr. a, without ; bragchia, gills).

Acalephs, 166 (Gr. akalephe, a nettle). — Sea nettles, or jelly-
fish. Their power of stinging is caused by microscopic thread-
cells in the integument.

Acanthocephali, 335 (Gr. akantha, a spine, and Jcepliale, a
head). — An order of parasitic worms.

Acanthacese. — A natural order of plants. The seeds of many
genera have hygroscopic hairs with spiral fibres, which make
them interesting microscopic objects.

Acarinae, 179, 338 (Gr. akari, a mite). — An order of the
Arachnidae, of which the cheese-mite is the type.

Acephalocyst (Gr. a, kephale, kustis, a headless bladder). —
Simple sacs filled with transparent liquid, usually known as
hydatids. They are the cysts of Echinococci, in which the
animals have disappeared or have been overlooked.

26

402 INDEX AND GLOSSARY.

Acetic acid, 67.

Acetate of potass, 75.

Achyla, 136. — -Microscopic plants, either Algae or fungi,
found parasitically on the bodies of dead flies in water, also
on fish, etc.

Achorion Schcenleinii, 329. — A microscopic vegetation oc-
curring infavus (a skin disease).

Achromatic (Gr. a, and chroma, color). — Without chromatic
aberration.

Achromatic object-glasses, 25.
44 condenser, 33.

Acinetse, 162 (Gr. akinete, fixed). — Infusorial animals, for-
merly supposed to be intermediate stages in the development
of Vorticellae.

Accessories, microscopic, 32.

Actinia, 165 (Gr. aktin, a sun ray), — Sea anemones, or Ac-
tinoid polyps. Formerly called animal flowers.

Acids, tests for, 109.

Adenoma, 272, 287 (Gr. aden, a gland). — A glandular tu-
mor.

Adenoid Tissue, 194. — Glandular tissue.

Adulteration of food, 323.

Adjustment, 51.

JEcidium, 363 (Gr. wheel-like]. — Minute parasitic fungi
(Order, Coniomycetes or Uredoideae), like little cups with red-
dish or brownish spores when mature. Earlier they are mi-
nute spots on the plants they infest. Known as " blight,"
44 brand," etc.

^Etiology, 321 (Gr. treatise on causes'). — The doctrine of
the causes of disease.

JEroscope, 321.

Agriculture, microscope in, 18.

Air-pump, 79.

Albuminous infiltration, 244.
44 compounds, 184.

Albuminuria, 303.

Alcohol, 68, 108, 252.

44 and acetic acid, 68.
44 and soda, 68.

INDEX AND GLOSSARY. 403

Alkalies, tests for, 108.

Alkaloids, tests for, 18, 111.

Allantois, 204 (Gr. sausage-like). — An oblong sac developed
in the embryonic life of animals near the end of the intestine,
and serving for temporary respiration.

Alcyonium, 165. — A genus of Coralline polyps.

Algae, 139 (Lat. sea weeds}. — The great variety in form and
organization shown by this class of plants render it an inter-
esting field of microscopic research. The families of Desmids
and Diatoms have been particular favorites.

Alternation of Generations, 126. — This term denotes a form
of reproduction in which the }?oung do not resemble the parent
of the animal but the grandparent.

Alimentary canal in insects, 177.

Amides, 184. — A term used in chemistry to express a com-
pound ammonia, in which one, two, or three of the hydrogen
atoms are replaced by an acid radical.

Ammonia. — Volatile alkali. Used in preparing carmine
fluids, 69, 72. Test for ammonia, 107. Used as a test, 108,
111, 112. The crystals of ammoniacal salts are often beautiful
microscopic objects. The hydrochlorate forms cubes, octahe-
dra, and trapezohedra, but if crystallized rapidly makes pecu-
liar feathery crystals. It does not polarize. Crystals of oxa-
late, oxalurate, and purpurate of ammonia are beautiful objects
for the polariscope.

Ambulacra (Lat. ambulacrum, a place for walking). — Holes
or avenues in the shell through which the tube feet of Echino-
derms are protruded.

Amnion, 204 (Gr. amnos, a lamb). — One of the fetal mem-
branes of the higher vertebrates.

Amoeba, 121 (Gr. amoibos, changing). — Animals of simplest
form, composed of a glutinous living substance or bioplasm.

Amoeboid Cells, 121, 128. — Cells with movements similar to
Amoeba have been found in vegetables as well as animals. See
Bioplasm.

Amplifier, 26, 346.

Amphipleura Pellucida, 56. — A test diatom for high powers.
The valves are linear lanceolate, with a median longitudinal
line. No median nodule. The striae are exceedingly fine.

404 INDEX AND GLOSSARY.

Amylum, 132 (Gr. amuloa, starch). — Starch.

Amyloid. — A vegetable substance analogous to starch, but
turning yellow in water after having been colored blue by
iodine.

Amyloid Cell and Infiltration, 239. — A waxy or lardaceous
albuminate infiltrated among the tissues.

Analogy. — Resemblance in form but not in function, or in
function but not in form.

Analysis of urine, 300.

Analytic Crystals, 90, 113. — Crystals which analyze polarized
light, as tourmaline, nitrate of potass, boracic acid, uric acid,
iododisulphate of quinia.

Anatomy of insects, 17T.

Angioma, 269 (Gr. angion, a vessel). — Blood tumor.

Anguillula, 171 (Lat. anguis, a snake). — A genus of minute
animals, formerly classed among Infusoria, but now regarded
as nematoid Eutozoa. The t; eels " in sour paste and vinegar
belong here.

Angular Aperture, 25. — The angle measured by the arc of
a circle, the centre of which is formed by the focal point of the
objective, the radii being formed by the most extreme lateral
rays which the object-glass admits.

Anilin Staining -fluids, 69. Anilin Carmine, 69. — Anilin
colors are of great interest in chemistry and microscopy.
Anilin is a base, forming salts with various acids, as hydro-
chlorate, nitrate, and oxalate of anilin. The substitution deri-
vatives of anilin are very complex and their colors various.
Mauvine forms a purple solution ; rosanilin, known also as
fuchsin, magenta, etc., a deep red ; Hoffman's violet a rich
violet; anilin blues are numerous. There are also several ani-
lin greens, and chrysanilin dyes a golden yellow.

Animal parasites, 330.

Animalcule, 160. — (A little animal.) Usually applied to In-
fusoria, Rotatoria, etc., but formerly given also to many of the
lower Algae.

Animalcule cage, 41.

Animal histology, 182.

Annelidse, 337. — A gallicized form of Annulata.

Annulata, 172. — Ringed worms.

INDEX AND GLOSSARY. 405

Annual Rings, 156. — Concentric rings seen in sections of
Dicotyledonous stems. They probably indicate periods of foli-
age, and more than one may be produced in a year.

Androspore, 152 (Gr. a male seed). — A peculiar body set
free from a germ-cell during the development of (Edogonium,
and probably some other Confervacese.

Annulus of Ferns, 155. — The ring surrounding the capsule
which contains the spores.

Anomalous. — Irregular, contrary to rule.

Antennae, 175 (Lat, antenna, a yard-arm). — The jointed horns
or feelers of most Articulata.

Anther, 157 (Gr. anthos, a flower). — The case which contains
the pollen of a plant.

Antheridia, 154. — The so-called male organs of urn mosses
and similar plants.

Antherozoids, 152. — The fertilizing cells of some of the Con-
fervacese. Used also synonymously with Spermatozoids.

Aphides, 126. — Plant lice. Order, Hemiptera. Their pro-
duction is an example of the alternation of generation as well
as parthenogenesis,

Aphtha, 329 (Gr. to fasten upon). — Thrush, or muguet, a
disease of the mouth, etc., in children, or in adults towards the
fatal termination of chronic disease. Supposed to be the pro-
duct of Oidium albicans, or thrush fungus.

Aplanatic, 26 (Gr. without deviation). — Refers generally to
spherical aberration in lenses.

Apothecia, 154. — The shields of Lichens ; firm horny disks
arising from the thallus, etc., containing spores.

Aqueous humor, 220.

Arachnida, 338 (Gr, arachne, the spider). — The class of
animals containing spiders, scorpions, mites, etc.

Arachnoid Membrane, 225. — A delicate cobweb-like mem-
brane between the pia mater and dura mater of the brain.

Arachnoidiscus, 148. — A beautiful circular Diatom. The
markings vary. A. Ehrenbergii is common on the Pacific
coast.

Arcella, 159 (Lat. area, a chest). — A genus of Rhizopods.
The test of the common species, A. vulgaris, has delicate
markings like the valves of Diatoms.

406 INDEX AND GLOSSARY.

Archeus, 116. — In the theory of Yan Helmont, the specific
agent presiding over vital functions.

Archegonium, 155 (Gr. arche, beginning ; gone, seed). — The
early condition of the spore-case in mosses, ferns, etc. Also
called Pistillidium.

Arteries, 201. — Tubes conveying blood from the heart to the
capillaries. They have three coats, an outer, middle, and in-
ner coat. The inner is epithelial, the middle of unstriped
muscle, and the outer of fibrous connective tissue. Thej^ are
all supplied with nutrient bloodvessels, the vasa vasorum, and
have nerves from the ganglionic and spinal systems.

Arsenic, Tests for, 110. — Arsenious acid. The most com-
mon form of cr}Tstal is octohedral or tetrahedral, but a right
rhombic form may be obtained by sublimation. Protoxide of
antimony will also yield by sublimation similar crystals, re-
quiring discrimination in cases of poisoning.

Arthritic deposits, 241 (Gr. arthron. a joint).

Areolar fibroma, 268.

Ascaris, 336 (Gr. askeris, a round worm).

Asci, 154 (Gr. askos, a bottle). — A long or roundish spore-
case of fungi, containing spores. Called also thecse.

Ascomycetes, 138. — An order of fungi characterized by
asci.

Asellus, 172. — A. vulgaris, or water woodlouse, an Isopod
crustacean, is interesting to the microscopist since its trans-
parency permits a view of the circulation.

Aspergillus, 136, 325. — A genus of Mucedines, forming
moulds, as the blue mould on cheese, etc.

Asterias, 168 (Gr. aster, a star). — Star-fish.

Atheroma, 234 (Gr. porridge of meal). — A disease of the ar-
teries characterized by a pulpy deposit.

Atrophy of heart, 242 (Gr. a trophe, not nourishing).

Avanturine. — A mineral sometimes seen in cabinets consist-
ing of silex and scales of mica. Artificial avanturine is of
glass with crystals of metallic copper scattered through it.

Amcularia, 169 (Lat. avicula, a little bird). — The bird's-
head processes of the Potyzoa.

Bacillaria, 144 (Lat. bacitlum, a little staff). — A genus of
Diatomaceae.

INDEX AND GLOSSARY. 407

Bacillus, 297, 327. — A genus of Schizomycetous Fungi.

Bacterium, 135, 161, 315, 327 (Gr. bacterion, a staff). —
A genus of Schizon^cetous Fungi. These rodlike, moving '
filaments have been referred to the Algae as well as to the
animal kingdom. Their nature is very obscure. See p. 135.

Balsam (Canada), Liquid resin of Pinus balsamea, 73.

Balsam cement, 76.

Balsam mounting, 79.

Balanus, 174 (Gr. balanos, an acorn). — The acorn-shell, — a
family of Cirrhipeda.

Bathybius, 96, 158. — Gelatinous matter from the bed of the
Atlantic Ocean, supposed by Huxley to be of the family of
Rhizopods. Its animal nature is disputed.

Beale's generalization in biology, 118.

Beale on Inflammation, 248.

Beale's carmine fluid, 69.
" injecting fluids, 72.
" tint-glass camera, 40.

Beck's microscope, 32.

" economic microscope, etc., 345.
" iris diaphragm, 33.
" illuminator, 38.

Bedbug, 339. — Cimex Lectularius.

Bell's cement, 76.

Beroe, 167. — Formerly classed among the cilograde Acalephs,
now generally in the class (Ctenophora) of the sub-kingdom
Ccelenterata.

Bergmehl, 94. — Mountain flour. A powdery mineral, con-
sisting largely of the silicious valves of Diatoms. In times of
scarcity in some countries it is mixed with food.

Bile in urine, 303.

Binocular Microscope, 30 (Lat. binus, two ; oculus, eye).
" Eye-piece, 30.

Bichromate of Potash, 68.

Bipinnaria, 168. — The larval form of the star-fish, named
from the symmetry of its swimming organs. The star-fish is
developed around the stomach of the larva.

Biology, The Microscope in, 18, 116 (Gr. bios, life, and logos,
discourse).

408 INDEX AND GLOSSARY.

Bioplasm — living matter, 118, 122, 183.
as germs of disease, 339.

Bismuth test, 306.

Blastema, 124 (Gr, blastos, a bud). — A term given by the
early histologists to the fluid from which it was supposed cells
sprouted spontaneously.

Blastoderm, 201. — The membrane of the ovum from which
all the tissues sprout or originate.

Blight, 136. — A term loosely applied to a variety of diseases
in plants, as well as to the causes of such diseases, as insects
(animal blights) and parasitic fungi.

Bladder, 212.

Blood, 186.

Bloodvessels, 208.

Blood in disease, 295.

Blood-tests, 102, 105, 299.

Bone, 91, 195.

Boracic acid, 68,

Borax and carmine fluid, 69.

Botrytis, 18, 136.

Bowman1 s glands, 219.

Brain softening, 235.

Branchia (Gr. bragchia, the gill of a fish). — A respiratory
organ adapted to breathe air dissolved in water.

Brunswick black, 76.

Bread, 323. — Adulteration of flour is readily determined,
but the baking of bread affects the form of the starch-grains.
Various parasitic fungi and their spores may sometimes be
found on bread.

Brunonian movement, 53, 120. — Molecular motion of parti-
cles suspended in fluid.

Bryozoa, 168 (Gr. bruon, moss ; zoon, animal).

Buds, sections of, 157.

Bullseye condenser, 36.

Bunt, 136.

Cabinet, 81.

Calcium, chloride of, 75.

Calyptra, 154. — The hood of an urn-moss.

INDEX AND GLOSSARY. 409

Cambium. — The viscid fluid between the bark and wood of
Exogens, when new wood is forming.

Camera lucida, 39. — Used in microscopy for drawing the
optical image produced by it.

Calcification, 234, 241. — Infiltration of animal tissues with
salts of lime.

Camphor, 133.

Canada balsam, 73.

Cancer, 288 (Lat. cancer, a crab). — A malignant new for-
mation.

Canaliculi of bone, 196.

Capillaries, 201 — Minute vessels between the terminal ar-
teries and veins.

Carbolic acid, 74.

Carbo-hydrates, 184.

Carmine fluids, 69. — Carmine is a pigment made from cochi-
neal.

Cartilage, 195.

Catarrh, 254 (Gr. kata, down, and rheo, to flow).

Caseation, 233, 253. — Transformation of a fatty into a cheesy
substance.

Carbuncle, 298.

Carbonate of lime, 99, 314.

Caustic potash, 67.

Cauliflower excrescence, 295.

Cavernous tumor, 270.

Cavities in crystals, 89.

Cells, 77 (Lat. cellar, a little chamber).

Cell, 117, 118. — The elementary unit of organic structure.
" structure, 119.
" genesis, 124.
" wall, in plants, 129.

Cellulose, 67, 129. — The proximate principle of cell-mem-
brane in plants, and of the mantle of Tunicata.

Cellular plants, 134.

Cements, 75.

Cercomonas, 331 (Gr. kerkos, the tail ; monas, unity. — A
tailed infusorial monad.

410 INDEX AND GLOSSARY.

Cerebellum, 216.

Cerebral nerves, 216.

Cesium veneris, 167.

Cephalopoda, 171 (Gr. kephale, head ; poda, feet).

Characese, 154.

Chalk strata, 95.

Chemical reagents, 67.
" teste, 106.

products of decay, 231.

Chloride of sodium, 68.
" " gold, 70.

Chlorophyll, 133 (Gr. chloros, green ; phyllos, leaf ).— The
green coloring-matter of plants.

Cholesterin, 233 (Gr. cftofe, bile, and stear, suet).

Chlorides in urine, 302, 314.

Chromic acid, 66, 67.

Chloride of calcium, 75.

Chorion, 204 (Gr. chorion, skin).

C/M/fe, 190 (Gr. chulos, juice).

Cicatricial tissue, 262.

CWi'a, 124, 191 (Lat. cilium, an eyelash). — Minute, hairlike
bodies, on cells.

Ciliograda, 167 (Lat. cilium, and gradior, I walk).

Ciliated epithelium, 191.

Cirrigrada, 167 (Lat. cirrus, a curl or tendril).

Cirrhipeds, 174 (Lat. cirrus, and pes, a foot).

Cirrhosis of Liver (252). — Shrinking of the liver.

Circulation, 187.

Classes of microscopes, 28.

Ciliary motion, 161, 170.

Cleaning covers, 77.

Cleavage of yelk, 201.

Cloudy swelling, 244.

Coa/, 92.

Coccoliths, 96 (Gr. kokkos, a berry ; lithos, a stone).

Cochlea, 222 (Gr. kochlos, a spiral shell).

Coddington lens, 23, 82.

Colors of flowers, 133.

Coloring matter, 184.

INDEX AND GLOSSARY. 411

Collomia seeds, 130.

Colloid degeneration, 236 (Gr. holla, glue).
" tumors, 238.
" " of ovary, 239.

" cancer, 293.
Compressorium, 41.
Collinses Harley microscope, 32.

" graduating diaphragm, 32.
Compound microscope, 23.

" crystals, 89.

" tissues, 197.

" eyes, 176.
Condensers, Achromatic, 33.

" Webster's, 34.

" Readers, 34.

Condensing lens, 37.
Conifer se, 131.

Conidia, 137. — Reproductive granules of fungi and lichens.
Conjugation of cells, 140.

" in infusoria, 162.

Connective tissues, 67, 192.

Conchifera, 170 (Gr. concha, a shell ; /e-ro, I carry).
Contagium vivum, 339.
Condensing prism, 35, 347.
Correlation of force, 117.
Cornea, 220 (Lat. cornu, a horn).
Cora/, 164.
Corpus luteum, 215.
Cbssus ligniperda, 179.
Corti's organ, 223.
Corns, 192, 286.

Crinoids, 167 (Gr. krinos, a lily; etcfos, form).
Croupous exudation, 257.

" pneumonia, 259.
Cuttle-fish bone, 170.
Crystalline forms, 86, 114.
Crystallization, 100.
Crystallography, 89.
Crystalloid, 66. — Capable of crystallization.

412 INDEX AND GLOSSARY.

Cryptogamia, 152 (Gr. kryptos, hidden, and gamos, marriage).
— Plants with inconspicuous sexual organs.

Crustacea, IT 2.

Cyclops, 173.

Cypris, 173.

Cystin, 314.

Cryptococcus, 325.

Cyclosis, 129. — Fluid circulation in plant-cells.

Dammar mounting, 74, 79.

Barker's selenite stage, 44.

Dark-ground illumination, 35.

Daphnia, 173. — A genus of microscopic Crustaceans. The
water flea.

Deane's compound, 74.

Dead cells, 229.

" cell-membrane, 230.

Decapoda, 174 (Gr. deka, ten ; poda, feet).

Decaying protoplasm, 229.
" nerve, 230.
" fat-cells, 231.
" connective tissue, 231.
u elastic fibre, 231.
" cartilage, 231.
" force, 231.

Decomposing blood, 229.

Degeneration of tissues, 232.

Demodex folliculorum, 179.

Definition, 54. — Power to give a distinct image.

Dental tissue, 192.

Dentine, 196.

Development of tissues, 201.

Dentzia scabra, 132.

Development of fungi, 137.

Desmidiaceae, 140. — A family of Confervoid Algae. Micro-
scopic fresh-water organisms, generally green; epidermis not
silicious, as is the case with Diatoms. Reproduce by cell-
division, b}T zoospores, and by conjugation. The latter form
produces a sporangium, which is sometimes spiny, and has
been described as a species of Xanthidium.

INDEX AND GLOSSARY. 413

Family 1. Closterieae. — Cells single, elongated, never spi-
nous, frequently not constricted in 'the middle; sporangia
smooth.

Gen. — Closterium. Penium. Tetmemorus, Docidium.
Spirotsenia.

Family 2. Cosmariese. — Cells single, constricted in the mid-
dle ; sporangia spinous or tuberculated.

Gen. — Micrasterias. Euastrum. Cosmarium. Xanthidium.
Arthrodesmus. Staurastrum. Didymocladon.

Family 3. Desmidese. — Cells united into a filament , sporan-
gia spherical, smooth.

Gen. — Hyalotheca. Didymoprium. Desmidium. Aptogo-
num. Sphoerozosma.

Family 4. Ankistrodesmise. — Cells elongated, entire, small,
in fagot-like groups.

Gen. — Ankistrodesmus.

Family 5. Pediastreze. — Cells grouped in form of a disk or
star, or side by side in one or two short rows.

Gen. — Pediastrum. Monactinus. Scenedesmus.

Diabetic sugar, 305.

Diagnosis, microscope in, 295.

Diaphragm, Rotary, 32. — An instrument for intercepting
excessive rays of light.

Diaphragm, cylinder, 32.

u graduating, 33.

" iris, 33.

Diatomaceae, 56, 94, 141. — A family of Algae.

Diffraction of Light, 54. — Disturbance of the ray by the
edge of an opaque body.

Difflugia, 159.

Diphtheritic exudation, 260.

Discrimination of blood, 299.

Distomum, 335 (Gr. dis^ double ; stomata, mouths).

Disease germs, 339.

Dotted cells, 130.
" ducts, 131.

Double Refraction, 91. — The power some crystals have of
exhibiting two images.

Double staining, 347.

414 INDEX AND GLOSSARY.

Duchenne^s trocar, 234.

Dytiscus, 177 (Or. dytiskos, diving).

Ear, 222.

Earths, analysis of, 99.

Echinococcus, 171, 333 (Gr. echinos, a hedgehog; kokkus,
a berry). — Larval forms (scolices) of tapeworms, known as
" hydatids."

Echinodermata, 167 (Gr. echinos, and derma, skin). — Spiny-
skinned animals.

Ectosarc, 158 (Gr. ektos, outside ; sarx, flesh).

Eczema, 256. — A vesicular eruption on the skin.

Eggs of Insects, 175. — These are interesting microscopic ob-
jects from the variety of their forms, colors, and markings, and
the singular lids of many of them. The markings are analo-
gous to other unicellular organisms, as spores, pollen grains,
Desmids, and Diatoms.

Elastic fibres, 194.

Elaters, 154 (Gr. elater, an impeller), — In the Equisetacese,
elaters are four elastic filaments attached to the spore, which,
by their uncoiling, jerk the spore away from its position. They
seem to be formed by spiral fissures in the outer coat of the
spore. In liverworts (Hepaticeae) the}7 are elastic fibres coiled
in membranous tubes, and originate as spiral fibres of vessels.
They are supposed to assist in the dispersion of spores.

Elytra, 175 (Gr. elution, a sheath).

Electrical cement, 76.

Elephantiasis, 270. — A species of leprosy or skin disease.

Embryology, 204 (Gr. en, in ; bruo, I swell).

Embolism, 272. — Result of occluding clots in bloodvessels.

Embryonic cells, 263.

Enchondroma, 278. — Cartilaginous tumor.

Encephalon, development of, 203 (Gr. egcephalos, brain).

Encephaloid cancer, 292.

Endochrome, 152. — Used for cell-contents of Algae.

Endogenous stems, 156 (Gr. endon, within ; gennao, I bring
forth).

Endosmose, 129 (Gr. endon; otheo, I push). — The current
flowing inwards when diffusion of fluids occurs through a
membrane.

INDEX AND GLOSSARY. 415

Endothelium, 202 (Gr. endon; thallo, I bloom).
Entomostraca, 173. — A family of Crustacea.
Entozoa, 171, 330 (Gr. entos, within, and zoon, an animal).
Epiderm, development of, 203.

Epithelium, 190 (Gr. epi, upon; thallo, I bloom). — Cells
covering surfaces of animal bodies.
Epithelium in blood, 298.
" in urine, 309.
Epithelioma, 293. — A species of cancer.
Epizoa, 330. — Parasitic animals.
Eozoon, 84, 97 (Gr. eos, dawn ; zoon, animal),
Enamel, 192, 197.— Covering of teeth.
Equisetaceae, 155. — A family of Cryptogams.
Equisetum, 132 — A genus of Equisetacese.
Epiphytes, 324. — Parasitic plants.
Epiblast, 202. — Upper layer of blastoderm.
Errors of interpretation, 52.
Ether, 68, 108.
Eosin-staining, 348.
Eolis, 127.

Esophagus, 209 (Gr. oisophagus, the throat).
Examination of minerals, 85.

" of higher plants, 155.

u of sputum, 316.

" of the air, 321.

Excretions, 318. — Products of waste or decomposition in-
capable of further use in the body.
Exudation, 247, 253.

" corpuscles, 233.

Exogenous stems, 156 (Gr. exo, out, and gennao, to grow). —
Dicotyledonous plants.
Eyes, care of, 49.

" of insects, 176.
Eye-pieces, 26.
Eye-piece micrometer, 38.
Eye-glass, 23.

tissue, 1 95.
acids, 184.
degeneration, 233.

416 INDEX AND GLOSSARY.

Fatty infiltration, 243.

" " of liver, 244.

False membranes, 256.

Fermentation, 135.

" test for sugar, 306.

Feet of insects, 177.

Ferns, 155, 349.

Fehling's test for sugar, 305.

Fibres, 185.

Fibrillar connective, 194.

Fibrin, 253, 270 (Lat. ^6m, a fibre).

Fibrinous exudation, 256.

Fibro-cartilage, 195.

Fibroma, 267. — Connective tissue tumor.
" molluscum, 268.

Field-glass, 23.

Filaria in blood, 297, 337.

Fission of cells, 125.

Fixed oil in plants, 133.

Flannel, Natural. — Interwoven filaments of Confervae, re-
sembling coarse cloth, sometimes found in summer on the
margins of ponds.

Flatness of field, 55.

Flea, 339. Pulex Irritans. — The last segment of the abdo-
men of the female, called the pygidium, has disklike areolae,
which is sometimes used as a test-object.

Floscularia, 164. — A genus of Rotatoria.

Flint, 96.

Fluid media, 66.
" mounting, 80.
" cavities in minerals, 84, 89.

Flowers, 157.

Foraminifera, 95, 159. — Small calcareous shells full of pores
or foramina*

Formed Material, 118. — Structure produced by bioplasm.

Fossil plants, ^3, 156.

Food, examination of, 323.

Freezing specimens, 228.
" microtome, 228.

INDEX AND GLOSSARY. 417

Fraunhofer' 's Lines, 44, 101. — Dark lines in the solar spec-
trum, seen by the spectroscope.

Frog-plate, 41. — The common frog will afford means of
studying several kinds of structures. By scraping the roof of
the mouth with a scalpel, ciliated epithelium may be obtained
(page 191). The circulation of blood may be seen in the foot,
mesentery, lung, tongue, etc., by inclosing the frog in a wet
bag and extending the tissue over the aperture in the frog-
plate (page 187). The ova of the frog are frequently used in
the study of embryology, and the transparent parts of the
tadpole for observing the development of the tissues.

Fungi, 18, 121, 134, 138, 232, 324.
" in blood, 298.
" in urine, 311.

Galls. — Abnormal growths on vegetables produced by the
sting or eggs of Hymenopterous insects.

Gammarus pulex, 174, 320 (Gr. gammarou, a lobster, and
Lat. pulex, a flea).

Ganglia, 200. — Nervous knots.

Ganglionic Fibres, 199. — Remak's fibres.

Gas-chamber, 42.

Gasteropoda, 170 (Gr. gaster, belly ; podes, feet). — A class of
Mollusca.

Gelatinous injections, 71.

u connective tissue, 194.

Generative organs, 213.

Generations, alternation of, 126.

Germ-theory, 339.

" of Dr. Beale, 340. <

Germ-cell, 125. — Ovum.

Germinal Matter, 118, 122. — Another name for bioplasm —
living protoplasm or " cell-stuff."

Germinal vesicle, 201.
" spot, 201.
" plates, 202.

Germ-fungi, 325. — Gymnomycetes.

GerlacWs carmine injection, 72.

Geology, microscope in, 92.

Giant-cells, 265.

27

418 INDEX AND GLOSSARY.

Glass-covers, 77.
" slides, 77.
Glands of Brunner, 209. — Intestinal glands.

" u Lieberkuhn, 209. — Follicles of intestine.
Glandular Fibres, 131, — Woody fibres of Coniferse.

" Tissue, 200.— Gland structure.

" Epithelium, 191. — Lining of glands.
Globules, 185.

Glomeruli of kidneys, 212. — Arterial tufts of Malpighi.
Glioma, 277. — Tumor of nerve connective tissue.
Globigerina, 96. — A genus of Foraminifera.
Glycerin, 74, 228.— The sweet principle of fats.

" and gelatin, 74.
. " and gum, 74.

" mounting, 80, 228.
Goitre, 287. — Tumor of thyroid gland.
Goadby's solution, 75. »

Gold size, 75.

Goniometer, 86. — An instrument for measuring angles of
crystals.

Gonozooid, 166. — Sexual zooid of Hydroids.

Graduating diaphragm, 33.

Graafian Follicles, 215.— Follicles of the ovary.

Granules, 185.

Granulation, 262. — Mode of organization after suppuration.

" tissue, 262.

Grammataphora test, 57.

Gregarinse, 330 (Lat. gregarius, in flocks). — A family of
parasitic Protozoans.

Gundlach's objectives, 346.

" condenser, 347.

Gum, 134.

Gustatory Cells, 218.— Elements of organs of taste.
Guaiacum, test for blood, 300.
Hair, 191.

" of insects, 175.
" worms, 172.

Hardening tissues, 62, 224, 227.
Hartnach's microscope, 32.

INDEX AND GLOSSARY. 419

Haustellum, 177 (Lat. haustellum, a sucker).

Hsematin, 103 (Gr. haima, blood).

Heart, 208.

" i?i insects, 178.

Haversian Canals, 196. — Vascular canals in bone.

Hepaticse, 154. — Liverworts (Gr. hepar, the liver).

Hepatic Lobules, 210. — Elemental structures of the liver.

Herapathite, 113. — lododisulphate of quinia.

Heterologous Formation, 263. — A tumor differing from the
tissue it is found in.

HerscheVs doublet, 22.

High powers, 55.

Hipparchia Janira, 56. — A species of Lepidoptera.

Histo-chemis try, 185.

Histology, 128, 182 (Gr. histos, tissue, and logos, discourse).
— The science of tissues.

Histological preparations, 224.

Holotliuride, 168 (Gr. holos, the whole, and thura, a gate). —
An order of Echinodermata.

Holland's triplet, 23.

Homologous Formation, 263. — A tumor similar to the tissue
in which it is found.

House-fly, 339.

Huygenian eye-piece, 26

Hydroids, 165 (Gr. hydor, water, and eidos, resemblance). —
A class of Co3lenterata.

Hydrocyanic acid, test for, 107.

Hypersemia, 246 (Gr. hyper, excess ; haima, the blood).

Hypoblast, 202. — The lower layer of the blastoderm.

Illumination, 22.

Illuminators, oblique, 34.

11 dark-ground, 35.

Indigo-carmine fluid, 70.

India-rubber, 133.

Imbedding tissues, 62, 227.

Immersion Lenses, 25, 51. — Objectives requiring fluid between
them and the object.

Improvements in microscopes, 345.

420 INDEX AND GLOSSARY.

Indifferent Fluids, 61, 66.— Fluids which do not alter the
tissues.

Indifferent tissue, 264.

Infusoria, 160 (Lat. infusus, infused).
" families of, 163.

Infusorial earth, 94.

Inflammation, 246.

Inflammatory Corpuscles, 233. — Fatty degeneration of epi-
thelium.

Injecting, 64, 70.

Insects, 174, 177.

Intestinal canal, 206.
" worms, 331.
" discharges, 318.

Interpretation, errors of, 52.

Inverted microscope, 106.

Invertebrata, classes of, 180.

Involuntary muscle, 197.

lod-serum, 66. — Serum and iodine.

Iris-diaphragm, 33.

Ixodse, 338 (Gr. ia?o, to adhere).

Kellner's eye-piece, 26, 33.

Kidneys, 211, — Urinary glands.

Labyrinthodon, 97 (Gr. labyrinth, a labyrinth, and odontes^
teeth).

Labyrinth of Ear, 222. — Essential part of organ, consisting
of vestibule, semicircular canals, and cochlea.

Lacunsb of Bone, 196. — Cavities containing bioplasts.

Labium of Insects, 176. — Underlip.

Lactification, 233. — The last act of fatty degeneration.

Lardaceous Liver, 240. — Amyloid infiltration.

Lacticiferous Vessels, 131. — Containing milky juice, or latex,
of plants.

Lamps for microscopists, 50.

Lawson's dissecting microscope, 60.

Lasso-cells, 165. — Stinging cells of Polyps.

Leaves of plants, 157.

Leech, 172, 337. — Hirudo medicinalis.

Leiomyoma, 266. — Tumor of unstriped muscle.

INDEX AND GLOSSARY. 421

Lenses, 21.

Lerncea, 113. — Parasitic Crustacea.

Leptothrix, 136, 260, 328. — A fungus found on epithelium,
etc.

Lepidocurtis, 56. — An insect similar to Podura.

Lepra, 284. — A peculiar skin disease.

Leucocytes, 189 (Gr. leukos, white, and kytos, a cell). — White
cells.

Leucin, 232. — A chemical product of decay.

Lepidoptera, scales of, 175.

Leukaemia, 296. — Excessive number of white cells in
blood.

Lieberkuhn, 37.

Ligaments, 194. — Fibrous tissues connecting bones.

Light for microscope, 50.

Life, theories of, 116.

Living Bodies, Element of, 117. — Bioplasm or cell.

Litmus-paper, 107.

Ligneous Tissue, 130. — Sclerogen. Woody fibre,

Lichens, 154. — An order of Cryptogamous plants.

Liver, 210. — Largest gland connected with nutrition.

Lignites, 93. — Fossils of vegetable origin.

Liverworts, 154. — Hepaticese.

Ligula, 176. — Tongue of insects.

Lice, 339.

Lime water, 68.
" salts, 115.

Lipoma, 277. — Fatty tumor.

Liver-fluke, 335. — Distomum hepaticum.

Lister's antiseptic plan, 343.

Locomotive Organs, 215. — Bone, muscle, etc.

Low powers, 55.

Logwood staining fluid, 70.

Lungs, 213. — Organs of respiration.

Lutein Spectra, 105. — Spectra from juice of corpora lutea in
the ovary.

Lupus, 283. — A peculiar skin disease.

Lymphatics, 207. — Yessels of the lymph.

422 INDEX AND GLOSSARY.

Lymphatic glands, 207.
" radicles, 207.

Lymph, 189 (Lat. a stream). '

Lymphoid Organs, 208. — Having structure like lymphatic
glands.

Lymphangioma, 270. — Tumor of lymphatic vessels.

Lymphoma, 272. — Adenoid tumor.

Magnesia salts, 115.

Maltwood's finder, 48.

Magnifying power, 22, 40.

Margarine, 232.

Marine glue, 76.

Malignancy, 263.

Malpighian tufts of kidney, 212.
" vessels of insects, 178.

Measuring objects, 38.

Medium powers, 55.

Metric System, 38. — The French system of weights and
measures, based on the metre. The French unit of weight is
the gramme.

Metamorphosis, 126. — Change of form.

Mechanism of microscope, 27.

Medusse, 167. — Jelly-fish.

Melicertians, 164. — A family of Rotifera.

Membrane, 185.

Medullary Sheaths of Nerves, 199. — Sheath of axis.

" Eays, 156. — Cellular plates from the pith to the
bark in exogenous stems.

Mesoblast, 202. — The middle layer of the blastoderm.

Medulla Oblongata, 216.- — The upper part of spinal cord,
within the skull.

Metallic oxides, tests for, 110.

Microscope, compound, 23.
" testing the, 54.

Microspectroscope, 18, 44, 101.

Micromineralogy, 84.

Microchemistry, 98.

Microchemical analysis, 106.
" apparatus, 98.

INDEX AND GLOSSARY. 428

Microscopic accessories, 32.
" slides, 77.
" lamp, 37, 50.

" table, 50.

Micrometer, 38.

Microgonidia, 152. — Bodies resulting from segmentation of
motile cells in cryptogams.

Microcytes, 297. — Minute cells.

Microzymes, 135. — Minute molecules found in some diseased
products.

Migration of cells, 189.

Milk, 315.

Mites, 178, 338.— A famity of Arachnida.

Micrococcus, 325. — Minute vegetables, sometimes classed as
Algae.

Microsporon Audonini, 329. — Fungus of Porrigo decal-
vans.

Microsporon Furfur, 329. — Fungus of P^riasis.

Miliary tubercles, 274.

Moist-chamber, 41.

Holler's test-plate, 57.

Mounting objects, 76, 79.

Monera, 158. — A term given to the simplest forms of animal
life.

Mouths of insects, 176.

Molecular movement, 120.

" Coalescence, 128. — Action of chemical substances
on colloids in a nascent state.

Mosses, 154.

Moschus Javanicas, 187. — Musk deer.

Motions of objects, 53.
" of cells, 120.

Morbid anatomy, 226.

" changes in inflammation* 246.

Morphological products, 183.

Mould diseases, 328.

Mucus, 190,309, 314.

Mucous membrane, 206.
" exudation, 254.

424 INDEX AND GLOSSARY.

Mucoid degeneration, 235.

Mucous polypi, 287.

Mucin, 235.

Mucor, 136, 325. — Mould-fungus.

Muriatic acid, 67.

Mullens eye fluid, 68, 227.

Muscardine, 18, 136. — A fungous disease in silkworms.

Multipolar nerve-cells, 199. — Cells with many fibres.

Muscle, 197.

" in insects, 179.
Muscular tissue growths, 266.

Mycelia of Fungi, 135, 137. — Filaments of vegetative
cells.

Myelon, 203. — Spinal cord.
Myxoma, 268. — Gelatinous tumor.
Nachet's inverted microscope, 32.

" prism, 35.

Nais, 172. — A genus of Choetopodous worms.
Nails, 192.

Ndevus, 269. — A vascular tumor.
Naphtha and creasote, 74.
Navicula rhomboides, 56.
Necrosis, 229.— The death of tissue.
Necrosed muscle, 230.

Nematoid worms, 171 (Gr. nema, a thread, and eidos, form).
Nerve tissue, 198, 217.
" fibres, 199.
" cells, 199.
" preparations, 217.
Neurilemma, 199. — Sheath of nerve-fibre.
Neuroma, 266. — Tumor on nerve.
Nicholas prism, 43.
Nitrogenous substances, 67.
Nitric acid, 67.
Nitrate of silver fluid, 70, 108.

" " -injection, 73.

NoberVs lines, 56.

" illuminator, 35.
Nose-piece, 47.

INDEX AND GLOSSARY. 42$

Nostochinse, 151, 322.— A family of Confervoid Algae.

Notochord, 203. — The gelatinous column forming the pri-
mary state of spine in vertebrates.

Nucleus of Cells, 119.— New centres of living matter.

Nutritive organs, 206.

Numbering blood-corpuscles, 296.

Oberhauser's drawing apparatus, 39.

Object glasses, 25.
" finders, 48.

Oblique Illumination, 34. — Light thrown obliquety through
an object.

Ocular micrometer, 38, 296.

Ocelli, 176. — Facets of compound eyes of insects.

(Ecoid, 188. — A constituent of the red blood-corpuscle.

Octospores, 153. — Subdivisions of sporangia in certain
Algae.

Oidium Albicans, 329. — Thrush-fungus.

Oil of cloves, 68, 80.

Oolites, 90. — Rocks whose structure resembles eggs of fish.

Oospores, 152. — Reproductive cells of Oscillatoria.

Operculum, 154. — The lid of spore-capsules in mosses, etc.

Opaque injections, 65, 70.
" objects, 77.

Orbitalites, 159. — Foraminiferous shells in limestone.

Organic principles, 183. — Formative materials.

Organization after inflammation, 261.

Organ of Corti, 223. — A complicate apparatus in the inner
ear.

Organs of special sense, 218.

Origin of rocks, 92.

Oscillatorise, 151. — A family of Confervoid Algae.

Osmic acid, 70.

Osseous tissue, 195. — Bone.

Osteoblasts, 196. — Cells developing bone.

Osteoma, 278. — An osseous tumor.

Osteochondroma, 278. — An ossifying enchondroma.

Ovum, 201 — Egg.

Ovary, 214. — Essential organ of reproduction in the female.

Ovipositors, 177.

426 INDEX AND GLOSSARY.

Oxalic acid, 67.

Oxalate of ammonia, 108.
" " lime, 313.

Pabulum, 118, 183. — Nutritive material of cells.

Pacinian fluid, 75.

" corpuscles, 218.

Papilloma, 285. — Papillary tumor.

Palaeontology, 97. — Science of fossils.

Palmellacese, 139. — A family of Confervoid Algae.

Palate of Molluscs, 171. — Tube set with siliceous teeth.

Parasites, 324. — (Gr. para, by the side of, and sitos, nour-
ishment),

Paraphyses, 154. — Elongated cells in spore-cases of lichens-

Parasitic Crustacea, 173.

Parthenogenesis, 126. — Reproduction without sexual union.

Pathological histology, 226.
" specimens, 227.

" new -formations, 262.

Parabolic illuminator, 36.
" speculum, 37.

Pancreas, 210. — A salivary gland of the intestines.

Penetration, 55 — Exhibition of structure below the focal
layer.

Periscopic eye-piece, 26.

Perforating glass, 78.

Penicillium, 136, 325. — A species of mould-fungus.

Peristome, 154. — Toothed fringe or spore-capsule of mosses.

Pernicious anaemia, 297.

Perivascular Canals, 207. — Lymphatic sheaths of vessels.

Peyer's Glands, 209. — Aggregations of glands in the walls of
intestines.

Pigmentation, 242. — Infiltration of pigment.

Pigment bodies, 232.
" in lungs, 242.
" bacteria, 326.

Pistillidia, 154. — Female organs of mosses, etc.

Phosphates, 313.

Photography, microscopic, 48.

Plant-sections, 153, 347.

INDEX AND GLOSSARY. 427

Phanerogamia, 155 (Gr. phaneros, visible, and gamos, mar-
riage).

Physograda, 167. — An order of Acalephs, now referred to
Hydroida.

Physalia, 167. — Portuguese man-of-war. — A genus of Hy-
droida. Sub-class, Siphonaphora.

Pleurosigma, 56.

Polariscope, 42, 99.

Polycystina, 95, 160, — An order of Rhizopods.

Polymorphism, 136, 324. — Various forms produced by the
same germ.

Polyps, 164 (Gr. polus, many ; pous, foot).

Polyzoa, 168 (Gr. polus, many; zoa, animals).

Polypary, 166. — The arborescent structure or Hydroids.

Polypite, 166. — The nutritive zooid or compound.

Polygastrica, 160 (Gr. polus, many ; gaster, the stomach).

Pollen in air, 322.

Porifera, 160. — Sponges.

Porpita, 167. — A genus of Hydroida.

Pond-stick, 81.

Podura plumbea, 56, 175. — A species of insects.

Family Podurellde.

Order Thysanura.

Polishing-slate, 94. — Tripoli.

Potato disease, 136. — A species of fungus.

Powers of objectives, 55.

Preparation of objects, 58, 61, 65, 84, 99, 156, 204, 277.

Preservative fluids, 73.

Preserving objects, 76.

Primordial Utricle, 129. — The bioplasmic layer of the vege-
table cell-wall.

Protoplasm, Il8, 128.—" Physical basis of life," or the ele-
mentary cell-material.

Progressive force, 130 .

Prothallium of Ferus, 126, 155. — An intermediate form be-
tween the spore and the plant.

Protopliytes, 129. — Primitive plants.

Protozoa, 158. — Simplest forms of animals.

Professional microscope, 345.

428 INDEX AND GLOSSARY.

Primitive groove of ovum, 202,
Pier o-car mine fluid, 70.
Prussian blue fluid, 70.
Pneumonia, 259. — Inflammation of lung.
Pus, 189, 248, 314.
Pustules, 255.

Pysemia, 272, — Pus in blood.

Pulmonigrada, 166. — An order of Acalephs, now generally
referred to Discophora (Hydroida).

Eadiolaria, 158. — An order of Rhizopods.

Raphides, 132. — Crystals in vegetables.

Readers condenser, 34.

Red blood-corpuscles, 186.

Reproduction, 125. — Multiplication of higher forms of life.

Resolution, 55. — Exhibition of minute details.

" after inflammation, 261.

Resin, 133.

Reticulated Vessels, 131. — Irregular deposit on walls of ducts.
Respiratory organs, 213.
Retina, 221.

Retrograde metamorphosis, 127.
Resting stage of cells, 140. — See still-cells.
Receptacles of Algde, 153. — The part which bears reproduc-
tive filaments.

Reticularia, 158. — An order of Rhizopods.
Recurrent fibroid tumor, 279.
Refractive media, 53.
Rhodospermex, 153. — Red sea-weeds.
Rhizopods, 158. — Root-footed Protozoa.
Rotatoria, 163. — Wheel animalcules.
Ringed worms, 337. — Annelidse.
Rhabdomyoma, 266, — Muscular tumors.
Rotifera, 160, 163.— Wheel animalcules.
Round worms, 171, 336.
Rust, 136. — A species of fungus.
Sarcode, 118. — A synonym for protoplasm.
Salivary glands, 209.

" " of insects, 178.

" corpuscles, 189.

INDEX AND GLOSSARY. 429

Sarcoma, 279.— Fibro-plastic tumor.

Sarcina, 328. — A vegetable organism sometimes classed
among Algae.

Sarcoptes Scabiei, 338.— Itch-insect.

Sandhopper, 174. — An amphipod Crustacean.

Sclerogen, 130. — Woody tissue,

Scales of Lepidoptera, 175.

Section-cutter, 63.

Sections of hard tissues, 62.

Secretory Organs, 208. — Glands.

Section of skin, 218.
" " crystals, 100.
" " embryo, 205.
" knife, 228.

Sebaceous Glands, 209. — Glands of skin secreting fatty matter.

Sea nettles, 166.— Jelly-fish.
" slugs, 167. — Holothuria, etc.
" urchins, 169. — Echinus, etc.

Serpula, 172. — A genus of Annulata.

Seise, 177. — Lancets of Diptera.

Sensory Organs, 218. — Organs of special sense.

Selenite stage, 44.

Seeds, 157.

Serous infiltration, 245.
" exudation, 253.

Screw bacteria, 327.

Scolex of Tapeworm, 332. — The head set free from the csyt
in development.

Scirrhus, 288. — Hard cancer.

Schacht's staining fluid, 68.

Scalariform Vessels, 155. — Vessels of ferns.

Showers of Flesh and Blood, 322. — Gelatinous masses, of
vegetable origin.

ShadbolVs turntable, 78.

Shell structure, 170.

Steel Disk, 40. — A substitute for the camera lucida.

Spectra, 102. — Lines or bands seen with the spectroscope.

Soil and water, examination of, 322.

Somatopleure, 203. — Layers of the embryo which form the
walls of chest and abdomen.

430 INDEX AND GLOSSARY.

Softening of brain, 235.

Sort, 155. — Fructifying spots of ferns.

Soda, 115.

Side reflector, 37.

Simple microscope, 21.

Smut, 136. — A species of fungus.

Sperm-cell, 125. — A synonym for spermatozoid.

Spectrum Analysis. 101. — Analysis by means of the spectro-
scope.

Spiral Motion, 130. — From progression of the centripetal
point in space.

Spiral Vessels, 131. — A spiral deposit in ducts of plants.

Spot lens, 36.

Sphagnum, 155. — Bog-moss.

Spherical Aberration, 22. — Errors in lenses from spherical
shape of surface.

Splicer -oplea, 152. — A species of Cryptogamous plants.

Sponges, 160. — Poriferous Rhizopods. Some form of them
a sub-class, Polystomata.

Spontaneous Generation, 125. — The theory of life without
parentage.

Spring clips, 80.

Spiders, 179. — Class Arachnida.

Spermatozoids, 201, 214, 311. — The male elements of im-
pregnation.

Splanchnopleure, 203. — An embryonic layer forming the wall
of the intestinal canal.

Sporangia, 154- — Spore-cases of Cryptogams.

Spinal cord, 216.
" nerves, 216.

Splenic fever, 297.

Spirilla 297, 328.— Screw bacteria.

Sputum, 316. — Discharges from the mouth.

Specific gravity of urine, 301.

Stage micrometer, 38.

Staining cells, 122.
" tissues, 63.
" fluids, 69.

Starch, 132.

Stems of plants,' 156.

INDEX AND GLOSSARY. 431

Still-cells, 140. — A condition of cells of the unicellular Algse,
distinguished from the motile state.
Student's microscopes, 28.
Strieker's gas-chamber, 41.

Star-fish, 167. — Order Asteroidea, Class Echinodermata.
Stings, 177.

Stemmata, 176. — Solitary eyes of insects, etc.
Striped Muscle, 198. — Voluntary fibres.
Stomata, 157. — Openings in epiderm of leaves.
Squamous Epithelium, 191. — Edges of cells overlapping.
Sublimation, 99. — Dry evaporation and condensation.
Surirella Gemma, 56, 58. — A test Diatom.
Suppuration, 262. — One of the results of inflammation.
Sugar in urine, 305.

Sucker Worms, 334. — Order Trematodes. Class Yermas.
Sweat glands, 209.

Sympathetic Nerve, 215. — The nerve of the viscera and blood-
vessels.

Syphilitic blood, 298.

Syphiloma, 281. — A tumor of s}^philitic origin.
Synovial Fluid, 190. — Secretion from the synovial membrane
of joints.

Table, 50.

Tardigrada, 164. — Water-bears.

Tapeworm, 171, 381.

Tactile Papillae, 218. — Organs of touch in the skin.

Tallow, 133.

Tests, microscopic, 54.
" micro-chemical, 106.
" for alkalies, 108.
" for acids, 109.
" foroxides,llO.
" for blood, 102.

Talitrus Saltator, 174.— The sandhopper.

Teleology, 19. — Exhibition of evidences of design in nature.

Teeth, 97, 196.

Tetraspores, 153.— Quadruple spores of Algse.

Terebratula, 170.— A genus of fossil shell.

Tessellated Epithelium, 190. — The cells lying edge to edge.

Termination of nerves, 200.

432 INDEX AND GLOSSARY.

Thin cells, 77.

Thread-worms, 336.

" capsules, 165. — Netting or lasso-cells of polypi.

Thecse, 155. — Capsules inclosing spores of ferns.

Theories of life, 1 16.

Thoracic Duct, 208. — Reservoir of the lymph.

Thwaite's fluid, 74.

Thiersch's carmine fluid, 69.
" blue injection, 72.
" red " 72.

Ticks, 179, 338.— Family Ixodse. Order Acarinro. Class
Crustacea.

Tissue elements, 185.

Torula, 135, 325.— The " yeast-plant " fungus.

Tow-net, 82.

T&nia, 171. — The tapeworm, called also Cestodes. See p.
331.

Transformation, 126, 264. — Variations in development.

Transparent injections, 72.

Triple phosphates, 232, 240, 313.

Tradescantia, 129. — A genus of Commebynacese, known as
spider-worts.

Trichomonas, 320. — A genus of Infusoria.

Tricophyton Tonsurans, 328. — The parasitic fungus of syco-
sis, etc.

Trommels Test, 305. — A test for sugar in urine.

Trichina Spiralis, 171, 337. — A species of Nematoid worm.

Tripoli, 94. — Polishing slate containing Diatoms, etc.

Thrombosis, 270. — Coagula of blood in the vessels.

Turntable, 78.

Tunicata, 169. — A class of Mollusca.

Tube casts, 311.

Tubercle, 234, 274, 276.

Tubuli Seminiferi, 214.— Tubules of the testes.

Turpentine, 68.

Tyrosin, 232, 314. — A chemical product of decomposition.

Uric acid, 242, 312.

Uredo, 136. — A genus of fungi, producing rust, etc.

Urinary deposits, 307.
" examination, 300.

INDEX AND GLOSSARY. 433

Urates, 313.

Ureters, 212.

Urea., 301.

Uriniferous Tubes, 211. — Glandular tubes of kidney.

Unstriped Muscle, 198. — Involuntary fibres.

Unipolar Nerve-cell, 199. — Cells with one fibre.

Umbilical Vesicle, 203. — An appendage of the vertebrate
foetus.

Ulvaceae, 151. — A family of Confervoid Algae.

Varieties of bioplasm, 123.

Vascular tissue, 201.

Valentin's knife, 62.

Vacuoles, 162. — Spaces or watery vesicles in the bodies of
Infusoria, etc.

Vaginal Discharges, 319.

Vernier, 43. — A short graduated scale, sliding on a larger
scale, so as to show fractions of divisions.

Vegetable cells, 128, 134.

Velella, 167. — A genus of animals now referred to the Hy-
drozoa.

Ventral Laminse of Embryo, 203. — Parts of the blastoderm of
the ovum.

Vegetative Organs, 206. — Pertaining to nutrition, etc.

Vesicles, 254. — Products of inflammation of the skin.

Vibriones, 135. — See Vibrio.

Vinegar Eels, 171. — A kind of Nematoid worms.

Vine Disease, 136. — A species of fungus.

Vtbrio, 327. — A genus of filamentous Bacteria.

Vibracula, 169. — Appendages of Polyzoa, from which vibra-
tile filaments project.

Vitellus, 201.— The yolk of the ovum.

Vitelline Membrane, 201. — The membrane surrounding the
yolk in the ovum.

Visual organs, 219.

Vitreous humor, 220.

Vorticella, 161. — A genus of Infusoria. Bell-shaped animal-
cules.

Volatile oil, 133,

Volvox, 140. — A genus of Confervoid Algae.

28

434 INDEX AND GLOSSARY.

Voluntary muscle, 197.

Vomited matters, 31 7.

Warm stage, 42.

Wandering-cells, 121, 247. — Leucocytes which traverse the
tissues.

Water-bears, 164. — The Tardigrada, placed by some in the
class Arachnida.

Water-fleasy 173. — Several kinds of microscopic Entomos-
tracan Crustaceans.

Wax, 133.

Water woodlouse, 172. — An Isopod Crustacean.

Warts, 192.

Wenham's prism, 30.

11 reflex prism, 347.

Webster's condenser, 34.

White blood-cells, 188.
" varnish, 76,

Woolaston doublet, 23.

Working distance, 51.

Woodward's prism, 347.

Xanthidia, 96. — Sporanges of Desmidiaceae found in flint.

Xanthoma, 277.

Yeast-cells, 136. — The Torula or yeast fungus.

FeZ/ow tubercle, 274.
" elastic fibre, 194.

F0/A-, 201. — Contents of the vitelline membrane of the
ovum.

Zentmayer's microscope, 30,

" Centennial microscope, 345.

" histological " 345.

Zooid, 188. — One of the constituents of the red blood-disk.

Zoea, 174. — The larval form of the crab.

Zoospores, 140.— Ciliated cells of Algae, etc., produced by
segmentation, and producing new individuals after being en-
cysted.

Zoology, microscope in, 158.

Zoophytes, 161. — Animal flowers. A name formerly given
to Actinea and other Hydroids.

Zygnema, 151. — A genus of Confervoid Algae.

June 1, 1880.

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Naval Hygiene; or, Human Health and means of Preventing Disease,
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WOODMAN AND TIDY.

A Text-Book of Forensic Medicine and Toxicology. By
W. BATHURST WOODMAN, M.D., Assistant Physician and Lecturer on Physi-
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WYTHE (JOSEPH H.), A.M., M.D.

The Physician's Pocket Dose and Symptom Book. Contain-
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Price, in cloth, 1.00; in leather, tucks, with pockets, 1.25

WYTHE (JOSEPH H.), A.M., M.D.

The Mieroseopist: A Manual of Microscopy and Compendium of the
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Practical Minerology, Assaying, Mining. Tenth PJditon.

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A Manual for conducting Business in Town and Ward
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MEDICAL PUBLICATIONS. 13

MEDICAL TEXT-BOOKS

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LINDSAY & BLAKISTON, PHILADELPHIA,

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Aitken's Science and Practice of Medicine. Third American, from the Sixth
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Sanderson's Hand-Book for the Physiological Laboratory. Exercises for
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Cazeaux's Text-Book of Obstetrics. From the Seventh French Edition, Revised
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ROBERTS' TEXTBOOK of He THEORY and PRACTICE of MEDICINE.

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below they give extracts from the medical press, American and English,
attesting its superiority and value to both student and practitioner. The
present edition has been thoroughly revised and much of it re-written.

" The best Textbook for Students in the English language. We know of no work in the English
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" It is a remarkable evidence of industry, experience, and research." — Practitioner.

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The Clinic.

" We particularly commend it to students about to enter upon the practice of their profes-
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SECOND EDITION, ENTIRELY RE-WRITTEN.

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" To many an earnest student it will prove a light in darkness ; to many a practitioner cast
down with a sense of his powerlessness to cope with the rout and demoralization of Nature's
forces, a present help in time of trouble." — Philadelphia Medical Times.

"The work throughout is a masterpiece of graphic, lucid writing, full of good sound teaching,
which will be appreciated alike by the practitioner and the student." — Student's Journal.

" Dr. Fothergill's intention has rather been to present the natural history of heart disease as a
series of vivid pictures before the imagination of the reader, and to carry the doctor as a living
actor into the scene. For this purpose he has properly chosen to use academic detail, not ex-
haustively, but as a means to this end, and he has brilliantly succeeded." — Westminster Review.

" The most interesting chapter is undoubtedly that on the gouty heart, a subject which Dr.
Fothergill has specially studied, and on which he entertains views such as are likely, we think, to
be generally accepted by clinical physicians, although they have not before been stated, so far as
we are aware, with the same breadth of view and extended illustration." — British Med. Journal.

" Dr. Fothergill's remarks on rest, on proper blood nutrition in heart disease, on the treat-
ment of the sequelae of it, and on the actions of special medicine, all indicate that, in studying
the pathology of heart disease, he has earnestly kept in view the best means of mitigating suf-
fering and of prolonging life." — The Lancet.

MEDICAL PUBLICATIONS. 15

AMERICAN HEALTH PRIMERS.

Edited by W, W, KEEN, M,D,,

Fellow of the College of Physicians of Philadelphia ; Surgeon to
St. Mary's Hospital, etc.

This series of American Health Primers is prepared to diffuse as widely and cheaply as possible,
among all classes, a knowledge of the elementary facts of Preventive Medicine, and the bearings and
applications of the latest and best researches in every branch of Medical and Hygienic Science. They
are not intended (save incidentally) to assist in curing disease, but to teach people how to take care of
themselves, their children, pupils, employees, etc.

They are written from an American standpoint, with especial reference to our Climate, Sanitary
Legislation, and Modes of Life; and in these respects we differ materially from other nations.

The subjects selected are of vital and practical importance in every -day life, and are treated in as
popular a style as is consistent with their nature. Each volume, when the subject calls for it, is fully
illustrated, so that the text may be clearly and readily understood by any one heretofore entirely
ignorant of the structure and functions of the body. The object being to furnish the general or un-
scientific reader, in a compact form and at a low price, reliable guides for the prevention of disease and
the preservation of both body and mind in a healthy state.

The authors have been selected with great care, and on account of special fitness, each for his subject,
by reason of its previous careful study, either privately or as public teachers.

Dr. Keen has supervised the Series, as Editor; but is not responsible for the statements or opinions
of the individual authors.

I. Hearing, and How to Keep It. With Illustrations. By

CHAS. H. BURNETT, M. D., of Philadelphia, Consulting Aurist to the
Pennsylvania Institution for the Deaf and Dumb, Aurist to the Presby-
terian Hospital, etc.

II. Long Life, and How to JReach It. By J. G. RICHARDSON,

M. D., of Philadelphia, Professor of Hygiene in the University of
Pennsylvania, etc.

III. The Summer and its Diseases. By JAMES C. WILSON,

M. D., of Philadelphia, Lecturer on Physical Diagnosis in Jefferson
Medical College, etc.

IV. Eyesight, and How to Care for It. With Illustrations. By

GEORGE C. HARLAN, M. D., of Philadelphia, Surgeon to the Wills (Eye)
Hospital.

V. The Throat and the Voice. With Illustrations. By J. SOLIS

COHEN, M. D., of Philadelphia, Lecturer on Diseases of the Throat in
Jefferson Medical College.

VI. The Winter and its Dangers. By HAMILTON OSGOOD, M. D.,

of Boston, Editorial Staff Boston Medical and Surgical Journal.

VII. The Mouth and the Teeth. With Illustrations. By J. W.

WHITE, M. D., D. D. S., of Philadelphia, Editor of the Dental Cosmos.

VIII. Brain Work and Overwork. By H. C. WOOD, JR., M. D.,

of Philadelphia, Clinical Professor of Nervous Diseases in the University
of Pennsylvania, etc.

IX. Our Homes. With Illustrations. By HENRY HARTSHORNE, M. D.,

of Philadelphia, formerly Professor of Hygiene in the University of
Pennsylvania.

X. The Skin in Health and Disease. ' By L. D. BULKLEY, M.D.,

of New York, Physician to the Skin Department of the Demilt Dispensary
and of the New York Hospital.

XI. Sea Air and Sea Bathing. By JOHN H. PACKARD, M. D.,

of Philadelphia, Surgeon to the Episcopal Hospital.

XII. School and Industrial Hygiene. By D. F. LINCOLN, M. D.,

of Boston, Mass., Chairman Department of Health, American Social
Science Association.

The volumes are sold separately. Price 50 cents each, neatly bound in cloth, or the set
complete, put up in boxes, price $6.00 ; with a specially liberal discount to the Trade when
ordered by the dozen volumes assorted, or in larger quantities.

PRESLEY BLAKISTON, Publisher,

1013 Walnut Street, Philadelphia,

1(5 LINDSAY & BLAKISTON'S MEDICAL PUBLICATIONS.

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NEW FEATURES FOR 1880.

A New Table of Poisons and their Antidotes.

The Metric or French Decimal System of Weights and Measures.

Posological Tables, slewing the relation of our present system of

Apothecaries' Weights and Measures to that of the Metric

System, giving the Doses in both.

This is a most valuable addition and will materially aid the Physician. So
many writers now use the metric system, especially in foreign books and
journals, that one not familiar with it is constantly confused, and in many
cases unable to understand the measurements or doses.

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UNIVERSITY OF CALIFORNIA LIBRARY