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THE
OR,
ON THE
USE OF THE MICROSCOPE:
FOR
PHYSICIANS, STUDENTS,
AND ALL
LOVERS OF NATURAL SCIENCE.
WITH ILLUSTRATIONS.
BY
JOSEPH H. WYTHES, M.D.
PHILADELPHIA:
LINDSAY AND BLAKIS TON.
1851.




Entered, according to Act of Congress, in the year 1851,
BY LINDSAY AND BLAKISTON,
In the Clerk's Office of the District Court for the Eastern District of Pennsylvania.
C. SHERMIAN, PRINTER.




TO
PAUL BECK  GODDARD, M.D.,
DISTINGUISHED BY
lIIS ARDENT AND SUCCESSFUL PROSECUTION
OF
THIS AND KINDRED STUDIES,
IS RESPECTFULLY INSCRIBED
BY
THE AUTHOR.








PR P E F A C E.
SINCE the employment of achromatic instruments, microscopic research has ceased to be merely an amusement, but has been elevated to the dignity of a science;
yet, so far as the author knows, no book has been issued
from the American press which would serve as a guide
to those desirous of applying themselves to such studies.
The present work aims to supply this deficiency.  In
its preparation the author has aimed less at style than
at information.  Its matter has been condensed into the
smallest possible space, so that it may be, what its title
professes,'.A Complete Manual on the Use of the Microscope."  It does not supersede the necessity of more
elaborate works, especially in the departments of Minute
Anatomy and Pathology, but gives directions by which
such works may be more profitably employed by the student. The multiplied labours of many observers have
been classified and arranged, and free use has been made




X                    PPRE EAC 1,E.
of English authorities, so as to bring the work up to the
present standard of information; at the same time the
opinions and experience of the author have been stated
without hesitation.
Respecting the construction of the Microscope itself,
a brief description is all that was deemed necessary; nor
could it have been much more extended without being
liable to serious objection.  As to the employment of
the instrument upon the various objects of science, as
full an account has been given as was consistent with
brevity; and to make this department more complete,
reference has been made to the doctrines and discoveries
of modern Physiology and Pathology.
The work is committed to the notice of the scientific
community with the hope that it may prove of service in
the study of the wonderful works of the Great Creator,
who is " all in all, and all in every part;" whose Power
and Wisdom are seen as well in the minutest atom as in
the most gigantic masses; and whose government embraces not only intelligent free agents, but also the
smallest animalculke existing in a drop of stagnant water.




CON T ENT S.
PAGE
CHAPTER I. THE HISTORY AND IIPORTANCE OF MICIOSCOPIC
INVESTIGATION,....   13
II. THE-I MICROSCOPE,....       22
III. ADJUNCTS TO TIHE MICROSCOPE,..   40
IV. How TO USE THE MICROSCOI'E,..       49
V. ON MOUNTING AND PRESERVING OBJECTS FOR
EXAMINATION,...          53
VI. ON PROCURING OBJECTS FOR THE MICROSCOPE,       64
VII. TEST OBJECTS,....   98
VIII. ON DISSECTING OBJECTS FOR THE MICROSCOPE,   105
IX. THE CELL-DOCTRINE OF PHYSIOLOGY,..  114
X. EXAMINATION OF MORBID STRUCTURES, ETC.,    124
XI. ON MINUTE INJECTIONS,..      134
XII. EXAMINATION OF URINARY DEPOSITS,.      143
XIII. ON POLARIZED LIGHT,.162
XIV. MISCELLANEOUS HINTS TO MICROSCOPISTS,.       170








THE MICIROSCOPIST.
CHAPTER I.
THE HISTORY  AND IMIPORTANCE OF MICROSCOPIC
INVESTIGATION.
FRoM the earliest period of scientific research, the magnifying properties of lenses have been used to penetrate the arcana
of nature, and with most striking results.. A vast amount of
information, which could have been obtained in no other way,
has been added, by microscopic observation, to almost every
branch of natural science.
To the Christian philosopher, the microscope reveals the
most amazing evidence of that Creative Power and Wisdom
before which great and small are terms without meaning. He
rises from the contemplation of the. minutie which it displays,
fe-eling more strongly than ever the force of those beautiful
words —" If God so clothe the grass of the field, which to-day
is, and to-morrow is cast into the oven, shall he.not much more
clothe you?  0 ye of little faith 1"
To the geologist, it reveals the striking, yet humbling fact,
that the world on which we tread is but the wreck of ancient
2




14                THE  MICROSCOPIST.
organic creations.  The large coal beds are the ruins of a
luxuriant and gigantic vegetation; and the vast limestone
rocks, which are so abundant on the earth's surface, are the
catacombs of myriads of animal tribes which are too minute
to be perceived by the unassisted vision.  It exhibits, also,
that metallic ore, as.the Bog Iron Ore, and immense layers of
earthy and rocky matter, are formed merely by the aggregation
of the skeletons or shields of Infusoria; while beds of coral
rocks are still in the process of formation, the architects being
tiny marine polypi. Further, by this instrument, the nature
of gigantic fossil remains is often determined, and by it they
are assigned their true place in the classification of the
naturalist.
To the student of vegetable physiology, the microscope is an
indispensable instrument. By it he is enabled to trace the
first beginnings of vegetable life, and the functions of the different tissues and vessels in plants.
The zoologist finds it also a necessary auxiliary. Without
it, not only would the structure and functions of many animals
remain unknown, but the existence of numerous species would
be undiscovered.
It is to the medical student and practitioner, however, that
the microscope commends itself for its utility.  A new branch
of medical study-histology-has been created by its means
alone; while its contributions to morbid anatomy and physiology, or pathology, are indispensable to the student or physician who would excel, or even keep pace with the progress of
others, in his profession. To such the following remarks will
doubtless be interesting.
Histology is that science which treats of the minute or ultimate structure and composition of the different textures of
organized bodies. It is derived from  erops, a tissue or web, and
Xo0yo, a discourse,




HISTORICAL INVESTIGATION.                    15
The attempts made by the early microscopic observers to
determine ultimate structure, were in general of little value,
partly on account of the imperfections in the instruments employed, and partly from the mistakes they made in judging of
the novel appearances presented to their view. This last cause
of error still exists, and inexperienced observers may very
readily be led astray.  By such, a fibre of cotton upon the
stage of the microscope,  moving in obedience to the hygrometric
influence of the breath or of a moist atmosphere, might be regarded as a living animal; or the influence of various reagents
on pus, mucus, blood, or other matters, might lead to error.
This last was the case with the celebrated Borelli, who was
the first to apply the microscope to the examination of structure.
Borelli was born in 1608, and lectured as professor in the
University of Pisa in 1656.  In his day a general idea prevailed, that diseases were occasioned by animalcule existing in
the animal tissues and fluids.  An examination of abnormal
fluids with the microscope favoured this idea, as the globules
were immediately taken for living beings.  Borelli described
the pus globules as animalcules, and even says he has seen them
delivering their eggs. It will be seen that this was a very
natural mistake, when we remember that these globules contain
several minute granules, which make their escape when the
external envelope is broken or dissolved.  In this way we
often find the germs of truth in the curious speculations of
the early microscopists.
Malpighi was the first to witness the most beautiful sight
which the microscope can reveal,-the actual circulation of the
blood, thereby demonstrating the reasoning of Harvey to be
true. The first work he published, in 1661, comprises his
microscopic observations relative to the structure of the lungs.
Between this period and 1665, he published other tracts on




16               THE MICROSCOPIST.
the minute anatomy of the kidneys, spleen, liver, membranes
of the brain, &c., and several of the structures still retain his
nanme. I-e also paid attention to the anatomy and transformations of insects, the development of the chick in the egg, and
the structure of plants.  It will be perceived from  the last
remark, that the intimate connexion between animal and vegetable physiology was even then acknowledged. This connexion
has led to the establishment of the cell doctrine, or the theory
of the development of all organized tissues from cells.
Lewenhoeck has sometimes been called the father of micrography.  HIe was born at Delft, in Holland, in 1663, and
appears to have received a rather indifferent early education.
He first brought himself into notice by the skill with which
he ground glasses for microscopes and spectacles, and for improvements in those instruments; thus affording a good model
for microscopic observers: first attending to the optical and
mechanical construction of the instrument he was to employ. In
1690 he discovered and demonstrated the capillary blood-vessels.
He opposed the chemical doctrines which then reigned in medicine, which attributed disease to fermentation in the blood.
He objected; that if fermentation existed, air bubbles would be
seen in the vessels, which was not the case.  He showed that
the blood-globules were of different sizes and forms in various
tribes of animals; examined the brain and nerves, the muscles, the crystalline lens, the milk, and numerous other textures
and fluids; and made the interesting discovery of the spermatozoa, which he conceived to be of different sexes.  There can
be no doubt that he made numerous errors, but the whole subject being new, his errors were excusable; and his contributions
to science are still of the highest interest.
Swammerdam, Lyonet, and Ellis, after this period, greatly
extended our knowledge of the lower tribes of animals; while




HISTORICAL INVESTIGATION.                   17
Lieberkuhn, Fontana, and Hewson laboured successfully in the
department of histology.
To Lieberkuhn we owe the first good account of the anatomy
of the villi, and of the minute tubular glands of the small
intestine, which still bear his name. As a minute injector he
has never been surpassed.
Fontana examined the brain, nerves, muscles, and several
other textures, with great care, and his observations were extremely accurate.
iHewson is celebrated for his accurate observations on the
blood and lymph corpuscles.  He first demonstrated that the
blood-globules were fiat, with a central nucleus, and not round,
as had been previously supposed.
Nearly all the celebrated men alluded to, made use of the
simple microscope.  At this period the compound microscope
was very defective.  It was more of a toy than a scientific
instrument.
From an ignorance of many phenomena connected with the
microscope which are now well understood, many errors
resulted.  Optical illusions were mistaken for natural appearances, as was the case with Monro.  In his discoveries respecting the brain and nerves, he describes them  as being formed
of convoluted fibres, and in his examination of other textures
he saw the same fibres and always mistook them for nerves.
The fact was, that he made his observations while the direct
rays of the sun were transmitted through the substance under
examination, and the optical phenomena which were produced
led to the mistake.  He afterwards found them on the surface
of metals, and then frankly acknowledged his error.
Another source of early errors was the treatment to which
their preparations were subjected before examination. It is
now well known that animal tissue should be examined while
fresh and transparent. What result is it possible to draw from




18               THE MICROSCOPIST.
the observations of those who boil, roast, macerate, putrefy,
triturate, and otherwise injure the delicate tissues?  Most of
the tissues contain albumen, which, so treated, gives origin to
globules, and flakes of different forms; a circumstance which
has led several anatomists to conceive the basis of animal
structures to be globular.  Several late observers have also
made this mistake.
Messrs. Todd and Bowman, the learned authors of "The
Physiological Anatomy and Physiology of Man," present the
following sensible remarks respecting this subject,-" To make
microscopical observation really beneficial to physiological
science, it should be done by those who possess two requisites:
an eye, which practice has rendered familiar with genuine
appearances as contrasted with those produced by the various
aberrations to which the rays of light are liable in their passage through highly refracting media, and which can quickly
distinguish the fallacious from  the real form; and a mind,
capable of detecting sources of fallacy, and of understanding
the changes which manipulation, chemical reagents, and other
disturbing causes may produce in the arrangement of the elementary parts of various textures.  To these we will add
another requisite, not more important for microscopical than
for other inquiries; namely, a freedom  from  preconceived
views or notions of particular forms of structure, and an absence of bias in favour of certain theories, or strained analogies.
The history of science affords but too many instances of the
baneful influence of the idolca speck2s upon the ablest minds;
and it seems reasonable to expect that such creatures of the
fancy would be especially prone to pervert both the bodily and
the mental vision, in a kind of observation which is subject to
so many causes of error, as that conducted by the aid of the
microscope."
The invention of the achromatic object-glasses for micro



HISTORICAL INVESTIGATION.                  19
scopes formed the beginning of a new epoch in histological pursuits. Since that period, the confusion and opposition which
formerly existed among observers have diminished, and at
present only those differences remain which are incident to the
pursuit of any other branch of scientific study.
In our own times, the Germans seem to have taken the lead
in histological observations; and the reputation of the wellknown names of Ehrenberg, Miiller, Schwann, Schulz, Wagner,
Weber, and Valentin, principally depends on the discoveries
they have made by means of the microscope.
In Englandcl, the names of Carpenter, Todd, Bowman, Owen,
Cooper, Busk, Quekett, Bowerbank, and others, are connected
with microscopic research.
In our own country, a spirit of emulation seems excited,
which promises great advantage. Professor Bailey of West
Point, and our townsmen, Drs. Leidy and Goddard, may be
mentioned among others who have contributed to this result.
The recent lectures of Dr. Goadby (late minute dissector to
the Royal College of Surgeons, England), on microscopic
science, have done much to increase a desire on the part of
medical students and others to become practically acquainted
with this subject.  His lectures to the students of the Philadelphia College of Medicine, and at other places, were well
attended; as likewise were his private classes. Of his valuable suggestions I have frequently availed myself.
The advantage of a practical acquaintance with the microscope by medical men may be easily seen, and is readily
acknowledged.  Dr. Bennet, of Edinburgh, to whom  I am
indebted for much of the histological part of this introduction,
says-" I have lately had many opportunities of satisfying
myself that death may be occasioned by structural changes in
the brain, which are altogether imperceptible to ordinary vision,
and which have escaped the careful scrutiny of the first morbid




20               THE MICROSCOPIST.
anatomists in this city. Again, who would have imagined that
porrigo favosa, mentagra, aphtha, and other diseases, consist of
cryptogamous plants growing on the skin or mucous membranes? Surely facts like these hold out a strong inducement
to the histologist who prosecutes pathological inquiries."  In
another place he relates the following circumstance, which tends
to illustrate the same point: "A gentleman who had an abscess in the arm, observed one morning his urine to be turbid,
and to deposit a considerable sediment.  The practitioner who
attended him thought it looked like purulent matter, but before
finally forming his diagnosis, he asked me to examine it with
the microscope. I did so; but instead of finding pus corpuscles, discovered a large quantity of irregularly formed granules,
which I recognised to be fibrinous.  I immediately suggested
that the abscess was on the point of resolution, and I afterwards learned, that from  that time it rapidly disappeared.
The fact that fibrin, exuded into the tissues, and, subsequently
absorbed, passes off by the kidneys, was determined by the
microscopic observations of Schinlein and Zimmerman in Germany."
Many other instances might be adduced, were it necessary,
to show the importance of the microscope in diagnosis and in
practical medicine. It is not too much to hazard the assertion,
that in a few years the practitioner will find it as essential in
finding out the nature of disease, and the state of the system,
as the most valuable articles of the materia medica are useful
in medical treatment.  The following example will illustrate
the delicacy as well as utility of this mode of investigation.
A few evenings since, while entertaining a friend with some
microscopic views, he expressed a wish to see the red globules
of the blood; so, pricking the tip of his finger with a lancet, a
drop was extracted, which, after covering with thin glass, was
placed upon the stage of the microscope.  Observing the glo



IIISTORICAL INVESTIGATION.                  21
bules, with a greater tendency than usual, to run together into
rows, like piles of coin, I remarked to him, that his blood
assumed an inflammatory or a feverish appearance. He replied,
that he had been for about thirty-eight hours without sleep,
having sat up with a sick friend the night before, and having
some gastric irritation in addition, he had felt feverish all the
evening.  Observations on pus, mucus, the urine, and the
various forms of malignant tumours, &c., all exhibit the value
of this instrument to medical science.
In medico-legal researches the microscope has already proved
a valuable auxiliary. It has several times been employed to
ascertain the true nature of spots suspected to be blood-stains,
&c.; and in cases where human life was suspended upon its
decision.
In 1837, M. Ollivier was directed to ascertain whether any
human hair was attached to the blade of a hatchet seized in
the house of a person suspected of murder, and if this were
the case, to determine the colour of the hair. W~ith the microscope, Il. Ollivier ascertained that the filaments attached to
the hatchet were the hairs of an animal, and not of a human
being; and this was afterwards fully proved.




CHAPTER II.
THE MICROSCOPE.
THOSE who have examined a common magnifying glass (or
lens) know that it is necessary to hold it exactly at a certain
distance from the object viewed through it, in order that such
object may be seen with distinctness.  The point at which the
object must be placed is called the focus of the lens, and the
distance from the middle of the lens to the focus is the focal
lenfgth, or focal distance of the lens.
The cut represents sections of the different forms of lenses.
A, is a plano-convex lens.  B, double convex.  C, plano-concave.  D, double concave.  E, a meniscus.
Fig. 1.
A         B         a        D          E
The effect of the convex lens or of the meniscus is to cause
the rays of light which pass from any object through them, to
converge towards a point or focus; and the eye receiving those




THE  MICROSCOPE.                      23
rays after passing through the lens, sees the object apparently
magnified.  This principle is the basis upon which all microscopes are constructed.
The concave lens produces a precisely contrary effect to that
described above.  The rays of light diverge on passing through
it, and the object appears diminished in size.
SIMPLE  MICROSCOPES.
A plano or double convex lens, especially when mounted, or
arranged with conveniences for viewing objects, is called a
simple microscope.
The magnifying power of a simple microscope is in proportion to the shortness of its focal length. Thus, a lens of 2
inches focal distance, magnifies 5 diameters (or the superficies
25 times)-of 1 inch focus, 10 diameters —ths of an inch, 15
diameters-  inch, 20 diameters-i inch, 40 diameters — th
inch, 80 diameters-vloth inch, 100 diameters.
This table of magnifying powers is not invariably correct,
owing,to the difference of vision in different individuals, but it
is sufficient for all practical purposes.
Simple microscopes are mounted in a variety of ways, according to the purposes for which they are intended. Some
are made to turn upon a hinge into a case, so as to carry in the
pocket; and others are fixed on a handle, with a pin or small
pair of forceps in the focus, on which a small object, as an
insect, &c., may be placed.
The cut, Fig. 2, exhibits the arrangement of Dr. Withering's
Botanical Microscope, which is valuable from  its simplicity.
It consists of three brass plates, a, b, c, parallel with each other,




24                THE MICROSCOPIST.
to the upper and lower of which the stout wires, ct, e, are rivetted. The middle plate, b, which forms the stage for carrying
the objects, is made to slide up and down on these wires. The
upper plate, a, carries the lenses, i, and the lower one, c, sometimes carries a mirror, for reflecting the light of a candle or of
the sky through any transparent object which may be placed
on the stagQe. Into the stage a dissecting knife, A, a pointed
Fig. 2.
instrument, f, and a pair of forceps, g, are made to fit, and can
be readily taken out for use by sliding the stage down nearly
to the mirror.
A very useful kind of simple microscope was that invented
by Mr. Wilson; an early form of which is represented by Fig.
3. The body, A, A, A, A, which was made either of ivory, brass,
or silver, was cylindrical, and about two inches in length, and
one inch in diameter.  Into the lower end, B, the magnifiers
are screwed, and into the upper end screws a piece of tube, D,
carrying at the end, C, a convex glass, and on its outside a
male screw. Three thin plates of brass, E, are made to slide




THlE  MICROSCOrE.                   25
easily in the inside of the body to form the stage. One of
these plates, F, is bent semicircularly in the middle, for the
reception of a tube of glass, for viewing the circulation of the
Fig. 3.
A iigi   
O
blood in small fish, while the other two are fiat, and between
these last the object-sliders, K, are introduced. Between the
stage and the end of the body, B, is a bent spring of wire, HII,
to keep the stage and object steadily against the screw-tube.
The object is adjusted to the focus by turning the screw D.
This instrument was held in the hand in such a position that
the light of a lamp or candle might pass directly into the con3




26                THE MICROSCOPIST.
densing glass.  It was afterwards improved by the addition of
a handle placed at right angles to its body.
The best form of the simple microscope for viewing opaque
Fig. 4.
objects, is that represented by Fig. 4: a is a flat piece of brass
attached to the handle, p; it supports the lens-holder, i, and
through it passes the screw, b, which is connected to the backplate, c; a spring, e, keeps the plates, a, c, apart, and the nut,




THE  MICROSCOPE.                      27
d, adjusts the lens to the focus of the object, either on g or h.
But the chief merit in its construction consists in a concave
speculum or mirror of silver, kc, highly polished, to the centre
of which, at 1, the magnifying glass is adapted. This is screwed
into the ring i, and so held that a bright light, as from a candle or white cloud, is received upon the speculum (called a
Lieberkuhn, from  the name of its inventor).  The light so
received is concentrated upon the object, which is brightly
illuminated; and is adjusted to the focus of the lens by turning the nut d.
For minute dissection of animal or other tissues, which is
generally performed under water, as hereafter described, the
Fig. 5.
a Z
A
microscope of Mr. Slack, with the improvements of D)r. H.
Goadby, F.L.S., is the most efficient. The following is a description of the instrument employed by the latter gentleman
in his microscopic researches; and with which he has made a




28               THE MICROSCOPIST.
great number of beautiful preparations in minute anatomy,
entomology, &c. It consists of a box or case, which is represented by A, Fig. 5. The upper surfaces i, r1, are sloped off to
form arm-rests.  The front of the case (which is not seen in
the cut) is furnished with a flap or door, which has hinges at
the bottom and a lock at the top; so that the various parts of
the instrument may be packed up inside.
In the top of the box is a round hole, B, into which fits the
short piece of tube attached to the tin box, C, which is designed to hold the water in which the dissection is made. The
ring, D, is the lens-holder, which is adjusted to the proper
focus by means of the milled head, E, which moves the rack,
F, up and down, working inside the box A.  The lens-holder
has also a horizontal motion, by means of the rack and pinion,
G. Another horizontal motion is produced by a swivel joint
attached to F. Inside the box is a mirror, directly under the
hole B, so that the light can be directed upwards through any
transparent object at B.
When moderate power only is needed, a simple microscope
is the best instrument which can be used; and for the purpose
of making minute dissections it is also the most convenient;
but when a very high magnifying power is needed, combined
with distinctness of observation, a single (or simple) microscope is found to be imperfect: although very small lenses
have been made, which magnify exceedingly-quite enough
for all useful purposes.  Good lenses, of a high magnifying
power, may be made by drawing out a very narrow strip of
glass in the flame of a spirit lamp, and upon the end of the
thread thus formed, running a small globule by means of the
flame, which may be detached from its thread and placed between two thin plates of metal in which a small hole has been
drilled.




THE  MICROSCOPE.                     29
Optical Improvements in the Simple Microscope.-There
are imperfections of vision attending the use of all common lenses; arising either from the shape of the lens, or
from the nature of light itself when passing through a refracting medium. These imperfections are termed respectively,
spherical and chromatic aberrations. To lessen or destroy these
aberrations various plans have been proposed, with various
success. Mr. Coddington proposed a lens in the form of a
sphere, cut away round the centre, as at A, Fig. 6. This is
an excellent form for a hand lens, but is not often to be procured in this country; opticians preferring to dispose of the
Fig. 6.
C                                         A
Stanhope lens, seen at B. which is more easily made than the
Coddington lens, but is inferior to it.  C and D are doublets
proposed by Sir John Ierschell; the first of which consists of
two plano-convex lenses, a, b, whose focal lengths are as 2'3
to 1, with their convex sides together; the least convex next
the eye, D, consists of a double convex lens, a, next the eye,
and a meniscus, b. When these lenses are used for forming
images the lenses marked a should be next the object.
Other forms of doublets have been proposed, but by far the
3*




30                THE  MICROSCOPIST.
best arrangement of this kind is Dr.  Vollaston's Doublet,
which consists of two plano-convex lenses, whose focal lengths
are as 1 to 3; the plane sides of each, and the smallest lens,
placed towards the object. The lenses are set in separate cells
so as to adjust their proper distance apart, which is best done
by experimenting on their performance, although their distance is about the difference of their focal lengths.  Between
them  is a diaphragm  or stop, generally placed immediately
Fig. 7.
C
0
behind the anterior lens.  The stop was not employed by Dr.
Wollaston, as his lenses were of such high power that they




THE  MICROSCOPE.                     31
nearly touched each other; yet it is, nevertheless, found to be
essential to a good doublet.
A, C, Fig. 7, represent the lenses of the doublet, and B is
the diaphragm or stop. The manner in which the light is
refracted by this instrument, is shown by the lines proceeding
from each end of the object, 0. The dotted lines represent
the blue or most refrangible rays of the spectrum; the others
are the red rays. Those rays which pass through the centre
of the lens, A, are caused to pass through the hole in the diaphragm over to the margin of B, and those nearest the margin
of A pass next the centre of B; and so become nearly corrected: the imperfection of one being made to counteract that
of the other.
An improvement was made upon this by Mr. Holland, and
is called Hfollctnd's Tiplet.  It consists of a doublet in place
of the first lens, A, in the last figure; retaining the stop between it and the lens C. This form is the highest stage of
perfection which the simple microscope has ever yet attained.
The great objection to its use, however, is, that it must be
brought into such close proximity to the object, that it is impossible to cover such object except with the thinnest mica,
which  is objectionable  on  account of its liability to be
scratched.
Before dismissing the subject of single microscopes, it may
be well to remark, that for a low magnifying power, a double
convex lens is the best to use; but for medium or high powers,
a plano-convex lens, with the convex side towards the object;
or one of the doublets just described; is preferable.
THE COMPOUND  MICROSCOPE
Consists essentially of two convex lenses; an object-glass and
an eye-glass; as represented in Fig. 8.




32               THE MICROSCOPIST.
A is the object-glass, which forms a magnified image of the
object at C, which is further enlarged by the eye-glass B. An
Fig. 8.,/1 \;z z i77
VPadialsD I!sal'ded \ l / hIu~le'I       I I   \   \'R,'
I         If   -
I         /
I'
\1 I
i~ ~ i 
I\ ~I t 
x t/xlitI i/
additional lens, P, is usually added; for the purpose of en



THE  MICROSCOPE.                     33
larging the field of view.  It is called the feld-lens.  An
inspection of the dotted lines in the figure will show that many
of the rays pass beyond the reach of the eye-glass, B: an
image from these rays is represented at E. These rays are
intercepted by the field-glass D, and form an image at F, which
is viewed by the eye-glass.
In looking through a common microscope of this kind, the
observer will probably see rings of colour round the edge of
the field of view, and also similar colours around the edges of
the object he is viewing. These defects arise from the decomposition of common white light; and are called chromatic
aberration or dispersion.  The colours round the field of view
are produced by the defects of the eye-piece; and those round
the object, by the object-glass.  Again: if the object be
looked at through the instrument as before, its outline or
edges will be observed, not sharp and distinct, but thick and
confused. This is caused by the rays not being collected into
a perfect point as they were on the object itself.  This defect
is called  spherical aberration.  When an instrument has
neither its chromatic nor spherical aberration removed, it is
said to be uncorrected.
To conceal these defects there is generally a small hole or
stop behind the object-glass.  This is injurious to correct
vision, as it prevents a large portion of light from entering the
eye, and makes the objects appear dark, so that their true
structure cannot be made out.  When this is the case, the
instrument is said to want angular aperture. The stop referred to, however, is essential even to the moderate performance
of a common instrument.
To obviate all these difficulties, improvements have been made
both in the object-glasses and the eye-pieces. Wollaston's
Doublet has been found capable, when used as an object-glass
with the Huygenian eye-piece (hereafter described), of trans



34                THE MICROSCOPIST.
mitting a large pencil of light with great distinctness, having
an angular aperture of from  350 to 50~.  Mr. Holland's
Triplet, used in the same way, is capable of transmitting a
pencil of 65~ with distinctness and correctness of definition.
The achromatic object-glasses, as first proposed by Mr. Lister,
have however superseded all other attempts to improve the
compound microscope, and have raised it from the condition of
a mere toy, to be the most valuable instrument of scientific
research. They are made of plano-concave flint, and doubleconvex crown glass lenses, cemented together.  Three compound lenses form the object-glass for a microscope, as represented by Fig. 9, a, b, c. In object-glasses of a high power,
Fig. 9.
the anterior compound lens, a, has sometimes an adjustment to
render it suitable for objects either uncovered or covered with
glass of various thickness. The object-glass, thus made, is not
quite achromatic, being rather over-corrected as to colour, but
is finally corrected by using the iHuygenian eye-piece, shown in
Fig. 10.
This eye-piece consists of two plano-convex lenses, A, B, with
their plane sides next the eye. In the focus of A is the diaphragm or stop, C. The proportions of the focal lengths of
these lenses should be as 3 to 1, and their distance apart, onehalf the sum of their focal distances. Thus, if B be three




THE  MICROSCOPE.                    35
inches focus, A should be one inch, and their distance apart
two inches.
Fig. 10.
Sometimes, when a very fiat field of view is required, as in
the use of a micrometer eye-piece, the convex sides of the
lenses face each other.  It is recommended that for this kind
of eye-piece the lenses should be nearly of the same focal
length, and at a distance equal to two-thirds the focal length of
either.
A good compound microscope should be furnished with
many mechanical conveniences, in addition to the optical part
just described.  It should be capable of being steady in any
position from vertical to horizontal-have coarse and fine adjustments for focus-have a large and firm  stage, with ledge,
clips, &c.; and with traversing motions, so as to follow an
object quickly, or readily bring it into the field of view,-and
should have a concave and plane mirror, of two inches diameter, with a universal joint, and capable of being brought nearer
or farther from the stage, as likewise of reflecting a side-light.
A variety of forms have been given to the mechanism of the




36                THE  MICROSCOPIST.
compound microscope, many of which are very good, while
others are exceedingly objectionable.  Suffice it to say respecting them, that steadiness, or freedom  from  vibration, and
particularly freedom from any vibrations which are not equally
communicated to the object under examination and to the
lenses by which it is viewed, is a point of the utmost consequence. A microscope body containing the lenses, screwed by
its lower extremity to a horizontal arm, is the worst form conceivable.
The most celebrated artists in the manufacture of these
instruments are Powell and Lealand; Ross; and Smith and
Beck, of London. A microscope from the latter firm is represented in the frontispiece.
The body slides by a rack and pinion, moved by the milledhead, a, on a strong dovetailed bar; and has also a slow motion for delicate adjustment of focus, given by the milled-head
b. It is furnished with a sliding tube, c, for varying its length;
and with three sliding Huygenian eye-pieces, c, cd', id", of
successive powers.
The erecting glasses, y, are to be screwed, when employed,
into the other end of the sliding tube.  They rectify the
image, which is inverted when seen in the usual way.  Their
chief advantage is in microscopic dissection.
The stage has two steady rackwork motions, at right angles
to each other and to the axis of the body, given by the milledheads, e, e'; it has also a sliding and revolving plane, f, with
a ledge, g, for resting object-slips upon, and a sliding-piece, h,
with springs for clamping them.  An upright rod, i, is fixed
on this plane for mounting the forceps, v, or for the springholder, j, when a glass trough, In, is used. A profile of the
glass trough, with its diagonal plate of glass for confining an
object, is seen at u'.  At z, is a three-pronged forceps.
A large double mirror, k, concave on one side and plane on




THE  MICROSCOPE.                     37
the other, is supported by the cylindrical bar, 1, and may be
moved upon it vertically and sideways.
A movable diaphragm, in, is fixed under the stage for varying the quantity and direction of the light when transparent
objects are viewed.  The illuminating lens, n, is used for condensing light upon opaque objects; and a silver side-reflector
is for the same purpose. The bull's-eye lens, for increasing the
illumination, is seen at r.
An achromatic condenser, x, slides into the place of the
diaphragm, to give the utmost refinement to the illumination of
transparent objects.
The live-box, s, is for observing living objects between two
glass plates; and a second live-box, s', with screw collars for
objects in water. The screw is for regulating the depth of
water, and the degree of pressure employed.
A plate of glass, t, with a ledge, has a separate piece of thin
glass to lie upon it, for viewing animalcules, &c., in water.
The camera lucida, w, has its prism fixed on a short tube
with a slight side motion for adjustment, and fits on each eyepiece when its cap is removed.
The three Lieberkuhns, o, o', o", adapted to the objectglasses 2, 3, and 4, are applied by sliding them in front of
each respectively.  When one of these is used, the diaphragm
is to be removed, and the dovetailed piece, 2, may be slid in its
place, with one of the three dark wells or stops, p, 2p' p", which
will make a dark background. If the objects are mounted on
circular discs, g, the well will not be needed.
The object-glasses comprise four powers. No. 3 and No. 4
have the tube of their front lens movable for adjusting their
performance with objects either uncovered or covered with thin
glass. The graduated screw collar, by which the adjustment is
made, is seen at 5.
The high price of these instruments must necessarily put
4




38                THE MICROSCOPIST.
them out of the reach of those whose means are limited, and
our opticians seldom import them, except to order.  Of late,
however, a praiseworthy effort has been made to simplify the
construction of the mechanical parts, so as to bring the price
within the control of the generality of medical men and other
students of nature.  Mr. J. B. Dancer, Manchester, England,
furnishes a very complete microscope, with two object-glasses
and the necessary apparatus, for ~10.  Messrs. Powell and
Lealand have also fitted up an instrument with a stand of castiron, whose cost, exclusive of the object-glasses, is ~9. Other
manufacturers are also pursuing the same course.
From  the cause above referred to, the majority of microscopes used in this country are of French or German imanufacture. Chevalier and Oberhauser have furnished some excellent
instruments; but the construction of most of those used or
exposed for sale, is far inferior to the English. Hitherto, also,
the fashion in this country in regard to microscopes, has led
to the almost universal employment of high powers, to the
neglect of the others, so that it is exceedingly difficult to procure an achromatic object-glass with shallow magnifiers, notwithstanding the decided advantage to be derived from their
use.
REFLECTING MICROSCOPES,
In which the image was formed by a concave mirror instead
of a lens, are not now so much used as formerly. They are
generally complicated in structure, and are surpassed and
therefore superseded by the achromatic microscope.
The following is a simple reflecting microscope, invented by
Mr. S. Gray, and may be of some interest from its singularity.
A, Fig. 11, represents a brass ring, one-thirtieth of an inch
thick, whose inner diameter is about two-fifths of an inch.




THE MICROSCoPE.                      39
Having dissolved a globule of quicksilver in one part nitric
acid and ten parts water, he rubbed with it the inner surface
Fig. 11.
of the ring, which became silvered; having wiped it dry, he
put a drop of quicksilver within it, which, when pressed with
the finger, adhered to the ring, and formed a convex speculum.
When the ring was taken up carefully, and laid on the margin
of the cylinder, B, the mercury sank down, and formed a
concave reflecting speculum. The cylinder, B, is supported by
a pillar, which is attached to the foot, D.  The stage, G, is
for holding the object, and is adjusted to the focus by the screw
at C.




CHAPTER  III.
ADJUNCTS TO THE MICROSCOPE.
IN addition to the mirror, object-glasses, eye-glasses, and
the parts constituting the stand of a microscope, several accessory instruments are needed by those who would devote attention to microscopic researches.  The most necessary or useful
of these we proceed to describe.
The Diaplhr7agnm, for cutting off extraneous light when
Fig. 12.
viewing minute transparent objects, consists of a plate of brass
perforated with several holes of different sizes.  This revolves
on a pivot, so as to bring each hole in succession under the
object-glass. It is adapted under the stage of the instrument,
and is so essential in practice that few microscopes are made
without it.
The CEondenser.-This is an arrangement under the stage




ADJUNCTS  TO  THE  MICROSCOPE.                41
for condensing the light upon the object. The best instruments
employ an arrangement of achromatic glasses, similar to the
object-glasses, but its value is scarcely equal to its cost.  The
Wollaston Condenser is a short tube, in which a plano-convex
lens of three-fourths of an inch focal length, with its flat side
towards the object, is made to slide up and down. Dr. Wollaston employed a long tube with a stop between the lens and the
mirror, but Dr. Goring found it better to have the stop between the lens and the object, and a little out of the axis of
the lens.
A substitute for the achromatic condenser is found in Mr.
Varley's dark chamber. This is sometimes preferable to the
Wollaston Condenser, as the light is not decomposed by passing through a lens.
c, Fig. 13, is a plate of brass adapted to the stage, in which
is a short tube having a diaphragm or stop, a, whose aperture
Fig. 13.
is equal to what can be viewed by the microscope and no
larger. Below is a sliding tube, b6, with an aperture rather
larger than that at a. This last can be moved up and down
until the light at a is of the greatest intensity.  The aperture
at a is always in proportion to the object-glass employed.
Polarizing ApparatZus, (Fig. 14,) for viewing objects by
polarized light. It consists usually of two prisms of calcareous spar, in proper tubes; one below the stage, and the
other in the eye-piece. Sometimes a thin piece of tourmaline
is used in place of the prism in the eye-piece.
4*




42                THE  MICOROSCOPIST.
Erector. —This is sometimes supplied with the best instruments. It consists of a pair of lenses acting like the erecting
eye-piece of the telescope.  It is applied to the draw tube at
Fig. 14.
the end of the eye-piece towards the object-glass. It is only
used when it is desired to dissect with the compound microscope, as, without it, the position of the object appears reversed.
(Yondensirng Lens and Lamnp. —The Wollaston Condenser,
&c., is designed to concentrate the light which comes from the
mirror, directly upon the object; but the condensing lens and
lamp is used either for opaque objects, or to condense the light
upon the mirror itself. Two such lenses, as in the figure, are
generally used.  Dr. Goadby informed me, that after many
experiments he has found a bull's-eye lens, of three inches
focal length, the most efficient for the larger lens; and after
several trials with different sorts of lenses I am disposed to
agree with him.  Fig. 15 illustrates one mode of using the
condensers upon opaque objects. A, is the bull's-eye lens,




ADJUNCTS TO THE MICROSCOPE.                 43
which turns upon its axis, and slides up and down a stout wire
affixed to a steady foot. B, is the smaller lens, whose handle
Fig. 15.
sid/ s t                   k               n       e    e
slides through a socket, working on a hinge joint. Sometimes
a lens of this kind is affixed to the stage of the microscope.
C, is the object upon which the light is concentrated. D, the
lamp. To condense the light on the mirror, the lens, A, alone
is used. The lamp is of the kind called a fountain lamp, and
slides up and down a stem, on which it can be fixed at any
height by the screw F. E represents a section of a shade,
which should always be used with the lamp. As it is a matter




44                THE MICROSCOPIST.
of much consequence to our observations that we should have
a steady, intense light, it is not immaterial what kind of oil,
&c., we employ. After many trials and disappointments, I am
convinced that pure sperm oil is the pleasantest, cheapest, and
best.
Lieberkuhn, or Silver Cup.-This is a most useful instrument for viewing opaque objects.  It is attached to the objectglass in the manner represented by Fig. 16, where a is the
lower end of the body of the microscope, b the object-glass,
Fig. 16.
to which the Lieberkuhn, c, is attached.  The rays of light
reflected from  the mirror, are brought into a focus upon an
object, d, mounted in the usual way upon glass, or held in
the forceps, f. When the object is transparent, or is too small to
fill up the entire field of view, the dark well or stop, e, is used.
This is generally fixed into the centre of the stage, a little
below the upper surface. Sometimes, instead of a Lieberkuhn,
a side-reflector is used, and from the greater obliquity of its
reflection, is of great advantage in exhibiting delicate structures.




ADJUNCTS TO  THE  MICROSCOPE.                  45
It has hitherto been considered impracticable to use very
high powers with opaque objects, but the Athenneum informs
us that " at one of Lord Rosse's recent scientific soirees, Mr.
Brooke showed his new method of viewing opaque objects
under the highest powers of the microscope (the ith and Ulth
inch object-glasses).  This is performed by two reflections.
The rays from a lamp, rendered parallel by a condensing lens,
are received on an elliptic reflector, the end of which is cut off
a little beyond the focus; the rays of light converging from
this surface are reflected down on the object by a plain mirror
attached to the object-glass, and on a level with the outer surface. By these means the structure of the scale of the podura,
and the different characters of the inner and outer surfaces, are
rendered distinctly visible." I have not had an opportunity
of testing this plan, but have little doubt of its success.
camera Lucida.-By which drawings are made from the
microscope. This is generally formed by placing a small prism
of glass, inclined at the proper angle, in front of the eye-piece.
In Fig. 17, a, represents the camera, formed of highly-polished
Fig. r7.
steel, smaller than the pupil of the eye, inclined at an angle
of 45%, and fixed to a clip, b, which embraces the eye-piece.




46                THE  MICROSCOPIST.
Frog-plate; Fig. 18; on which frogs or fish are tied to examine the circulation of blood in their vessels.  The frog, &c.,
Fig. 18.
0
o  
o
o        o
must first be enclosed in a bag, and fastened on the plate by
the holes in either side of it. Then thread is tied to about
four of its toes, and the web is spread out over the large hole
by fastening the ends of the thread through the smaller holes
in the plate.
The Stage Micrometer consists of a slip of glass, pearl, &c.,
having a line finely divided into parts of an inch, &c. To
obtain with this the power of a compound microscope, compare
the divisions seen with one eye through the instrument, with
a rule held ten inches off, and looked at with the other eye.
Suppose, for instance, the micrometer be divided into ~l1oths
of an inch, and one of these divisions covers an inch of the
rule seen with the other eye, the magnifying power of the
instrument is 100 diameters.  If it should cover five inches,




ADJUNCTS TO THE MICROSCOPE.                  47
it is magnified 500 diameters.  By sketching the object by
means of the carmera, and then putting in its place a stage
Fig. 19.                      Fig. 20.
A    B    C         D
micrometer, and marking the divisions over the sketch, they
can again be subdivided, and so the measure of an object
be accurately taken.




48                THE  MICROSCOPIST.
Animalculee  Cage is a round cell with a glass bottom  and
top, for confining a drop of water with animalculse.
Watch- Glasses and Fishing Tubes, are useful adjuncts. The
latter, Fig. 19, are glass tubes of various sizes, by which when
one end is closed with the finger a quantity of water, &c., may
be lifted from a phial, as seen at Fig. 20, and put in a watchglass.  By their aid, too, with a little practice, an animalcula
may be caught in a phial, when it is visible to the naked eye.
With the finger on one end of the tube, approach the other
end to the place where the animal is, then suddenly lifting off
the finger, the current will carry it into the tube.
A  Comnpressorium, for applying pressure to an object; a
trough for chara and polypi; aphial-holder, &c.; will also be
found useful.




C HAPTER IV.
HOW  TO USE THE MICROSCOPE.
MANY persons imagine that the value of a microscope is in
proportion to the apparent size of an object seen through it.
This, however, is a mistake.  The greater the magnifying
power of an instrument, all other things being equal, the
greater is the difficulty of finding a minute object on the stage,
and of adjusting the focus.  The light, too, transmitted from
the mirror, becomes less intense, and the view less satisfactory
with the use of high powers. For the majority of objects, a
low or medium power is always preferable, on account of the
greater extent of the field of view. The test objects, however,
and the minute structure of any delicate tissue, &c., require
very considerable amplification in order to exhibit them satisfactorily.  When this is the case, the increase of power should
be given by the employment of an object-glass of shorter focal
length, in preference to the use of a more powerful eye-piece.
Sir David Brewster gives the following rules for microscopic
observations.
1. The eye should be protected from all extraneous light,
and should not receive any of the light which proceeds from
the illuminating centre, excepting what is transmitted through
or reflected from the object.-This rule will illustrate the use
of the diaphragm under the stage of the microscope.
5




50               THE- MICROSCOPIST.
2. Delicate observations should not be made when the fluid
which lubricates the cornea of the eye is in a viscid state.
3. The best position for microscopic observations is when
the observer is lying horizontally on his back.  This arises
from the perfect stability of the head, and from the equality
of the lubricating film of fluid which covers the cornea. The
worst of all positions is that in which we look downwards vertically.  The most common and easy position is generally with
the instrument inclined at an angle of 45 degrees.
4. If we stand straight up and look horizontally, parallel
markings or lines will be seen most perfectly when their direction is vertical; viz., the direction in which the lubricating
fluid descends over the cornea.
5. Every part of the object should be excluded, except that
which is under immediate observation.
6. The light which illuminates the object should have a
very small diameter. In the day-time it should be a single
hole in the window shutter of a darkened room, and at night
an aperture placed before an Argand lamp.
7. In all cases, particularly when high powers are used, the
natural diameter of the illuminating light should be diminished, and its intensity increased, by optical contrivances.
The following remarks by Mr. James Smith, copied from
the Microscopic Journal, vol. i., are recommended to the consideration of all who are in the habit of using microscopes.
"Much of the beauty of the objects seen depends upon the
management of the light that is thrown upon or behind them;
which can only be fully mastered by practice. It may be
remarked, however, as a general rule, that in viewing those
which are transparent, the plane mirror is most suitable for
bright daylight; the concave for a lamp or candle, which
should have the bull's-eye lens, when that is used, so close to
it that the rays may fall nearly parallel on the mirror. If the




HOW  TO USE THE  MICROSCOPE.                 51
bull's-eye lens is not used, the illuminating body should not
be more than five or six inches from the mirror.  The latter
is seldom  required to be more than three inches from  the
object, the details of which are usually best shown when the
rays from  the mirror fall upon it before crossing, and the
centre should (especially by lamp-light) be in the axis of the
microscope.  For obscure objects, seen by transmitted light,
and for outline, a full central illumination is commonly best;
but for seeing delicate lines, like those on the scales of insects,
it should be made to fall obliquely, and in a direction at right
angles to the lines to be viewed.
" The diaphragm is often of great use in modifying the light,
and stopping such rays as would confuse the image (especially
with low or moderate powers), but many cases occur when the
effects desired are best produced by admitting the whole from
the mirror.
" If an achromatic condenser is employed instead of the diaphragm, its axis should correspond with that of the body; and
its glasses, when adjusted to their right place, should show the
image of the source of artificial light, or, by day, that of a
cloud or window bar in the field of the microscope, while the
object to be viewed is in focus.
" The most pleasing light for objects in general, is that reflected from a white cloud on a sunny day; but an Argand's
lamp or wax candle with the bull's-eye lens is a good substitute.' A large proportion of opaque objects are seen perfectly well
(especially by daylight) with the side reflector, and the dark
box as a backgroundcl; and for showing irregularities of surface, this lateral light is sometimes the best; but the more
vertical illumination of the Lieberkuhn is usually preferable,
the light thrown up to it from the mirror below being, with
good management, susceptible of much command and variety."




52               THE MICROSCOPIST.
The management of the light with opaque objects must
depend in a great degree upon their size, and the manner in
which they are mounted. If the object is small, and so mounted as not to intercept much of the light from the mirror, the
mode illustrated by Fig. 16 is the best; in other cases, that
shown in Fig. 15 is preferable.
Next to the proper illumination of the object, the adjustment of the focus is the most important thing to be attended
to. With a low power, the coarse adjustment is usually su-ficient if the workmanship be good; but with a high power it
becomes necessary to resort to the more delicate arrangement
of the fine adjustment.  Great care must be taken, however,
lest the glass on which the object is mounted be broken, or
the object-glass injured, by too sudden or too close a contact.




CHAPTER V.
ON MOUNTING AND PRESERVING OBJECTS FOR
E XAMINATION.
IF a low power is used, and the object be one not necessary
to be preserved, it can be well seen if placed in the forceps or
on a slip of glass, but if it be desired to keep it for future
examination, some method of preserving it from decay, dust,
&c., must be resorted to; and the method will vary according
to the nature of the object.
TRANSPARENT OBJECTS.
Transparent objects are mounted on slips of glass, the size
of which, as adopted by the Microscopic Society of London, is
3 inches by 1 inch, or 3 inches by 11 inches.  The French
opticians, however, prepare many of their slides 21 inches by
Iths of an inch, and this size is most frequently imported into
the United States; indeed, a larger size is unsuitable for many
of the French instruments, although to be preferred on other
accounts.
There are three methods of mounting transparent objects.
Ist, in the dry way-in which the object is simply placed
upon the slip of glass, and covered with a thin glass cover,
cemented by its edges to the under piece, with sealing-wax
varnish, &c.




54                THE MICROSOOPIST.
2dly. In some preservative fluid.
3dly. In Canada balsam.
The glass slides should be clear, free from veins and bubbles, of uniform  length and breadth, and should have their
edges ground smooth by rubbing them on a flat cast-iron plate
with emery and water.
Sections of teeth and bone, and of some kinds of wood,
hairs of animals, scales of butterflies, test objects from the
infusoria, &c., are best mounted dry; but all very delicate
animal and vegetable tissues, to exhibit their structure clearly,
should not be mounted in the dry way, nor in Canada balsam,
but in some preservative fluid.
PRESERVING FLUIDS.-A very considerable number have
been recommended by different observers.  A mixture of salt
and water was used by Dr. Cook for this purpose; there is an
objection to it, however, owing to the development of a confervoid vegetable.
Mr. J. T. Cooper, some years since, made some experiments
with a view to determine the best fluid for preserving vegetable
coloured tissues, such as some of the smaller fungi, and found
that salt and water, 5 grains to the ounce of water, to which
acetic acid had been added, answered very well. A few drops
of creosote or of camphor will prevent the growth of conferve.
One part alcohol to 5 of distilled water-1 ounce to 4 of
water —will preserve even very delicate colours.  This is the
basis of the Gannal process for preserving animal structures.
There is, however, the same objection to the use of this fluid
as to the salt and water.
A weak solution of chromic acid is a good preserving fluid.
Pure glycerine is prepared by the London opticians as a
preservative fluid, and is used in the proportion of 1 part to 2
of water. Its oily nature, however, often causes much difficulty in cementing the thin glass cover upon it.




MOUNTING AND PRESERVING OBJECTS.   55
Dr. Goadby has devoted much attention to this subject, and
has succeeded in supplying to the microscopist a ready, cheap,
and effectual means for mounting animal structures with the
greatest possible ease and security. Dr. G. received a gold
medal from the Society of Arts for his invention. He has
kindly furnished me with the following description of his
different preserving fluids.
"A 1. Bay salt (coarse sea-salt), 4 ounces,
Alum, 2 ounces,
Corrosive sublimate, 2 grains,
Boiling water, 1 quart.
"' A 2. Bay salt, 4 ounces,
Alum, 2 ounces,
Corrosive sublimate, 4 grains,
Boiling water, 2 quarts.
"The A I fluid is too strong for most purposes, and is only
to be employed where great astringency is required to give
form and support to delicate structures.
" The A 2 fluid may be very extensively used, and is best
adapted for permanent preparations; but neither of these fluids
should be used in the preservation of animals possessing any
carbonate of lime (all the Mollusca), as the alum  becomes decomposed, and the sulphate of lime is formed and precipitated,
and the animal spoiled. For such use the
"B. fluid. specific gravity 1-100.
Bay salt, 8 ounces,
Corrosive sublimate, 2 grains,
Water, 1 quart.
" Marine animals require a stronger fluid of this kind, viz.,
specific gravity 1'148, which is made by adding more salt
(about 2 ounces) to the above.
" The corrosive sublimate is used to prevent vegetation grow



56                 THE  MICROSCOPIST.
ing in the fluid, and no greater quantity should be used than
2 grains per quart of fluid; but, as it coagulates albumen, it
must be left out when ova are to be preserved, or when it is
desired to maintain the transparency of certain tissues."
A paragraph has recently been published in the newspapers,
to the effect, that "a couple of French savans have simultaneously discovered that chloroform is an antiseptic of marvellous virtue, preventing animal decomposition after death, or
promptly checking it if already commenced.  All animal
tissues when subjected to its action become fixed for a long
period of time in the precise form and condition in which they
may happen to be at the moment of application, and natural
colours, even to the slightest and most delicate shades, are
preserved without the slightest change." If this be so, the
desideratum  in this respect will be supplied.  I have not had
an opportunity of testing it, but look upon it as quite probable.*
* Since the above was written, the following extract, confirming
the alleged discovery, appeared in-the Medical Examiner: —"M.
Augend has communicated to the French Academy of Sciences the
following experiments, which establish a marked line of demarcation
between ether and chloroform, and point out in the latter a remarkable property which has hitherto escaped the attention of chemists.
"If three wide-mouthed, ground-stoppered bottles are taken, and
into one we put a few drops of ether, into another a few drops of
chloroform, and leave the third in statu quo; then place in each a
piece of beef, secure the stoppers, and leave them during summer
weather, the following phenomena are observed:-The flesh, naturally of a reddish-brown colour, passes at once to a vermilion-red, under
the influence of the vapour of chloroform mixed with air, whilst it
undergoes no change in the ether. Such are the immediate effects,
but at the end of a week the results are still more distinct. The
flesh preserved in the air has changed its colour slightly, that which
is preserved in the ether has become brown, whilst that in the chloroform has acquired the appearance of boiled meat. On opening the
bottles, the meat in the air has become offensively putrid, and the




MOUNTING  AND  PRESERVING  OBJECTS.    57
MOUNTING IN FLUID.-The most minute structures, such as
the vessels of plants, and the muscular and other tissues of
animals, requiring in all cases high powers for their proper
exhibition, must of necessity be preserved in very thin cells
with a small amount of fluid.
On a slip of glass, 3 inches by 1, cleaned by a solution of
caustic potash to remove all grease, lay a drop of the fluid;
put the object in this and spread it out with the point of a
needle, &c. Select a thin and flat glass cover, clear it likewise
from grease, &c., touch its edges with cement, and drop it
gently over the object. Press it lightly, to exclude the excess
of fluid, which call be removed by strips of blotting-paper.
Then cement the edges of the cover to the bottom glass. Care
must be taken to exclude all air-bubbles from  between the
glasses. Objects mounted thus do not keep long, and it is
same thing occurs in the presence of the ether, whilst there is no
change in the flesh kept in the chloroform, apart from the sweet taste
and peculiar odour of the latter.
"c These antiseptic properties of chloroform have furnished interesting results to M. Augend. He has found that 1-2000th part of it (?)
suffices to preserve a mass of muscular flesh. Not less remarkable
is the facility with which the vapour permeates the densest tissues.
Chloroform has this advantage over creosote, that it does not coagulate the albumen; nor is it on its part decomposed by muscular
fibre.
"' The most apparent action of the chloroform, not only on muscular substance, but also on the fleshy pericarps of fruits and seeds, is
an immediate contraction of the fibre or the parenchyma, which
causes the watery juices to flow out on the bottom of the vessel in
which the experiment is made.-Gazette ledicale."
From the foregoing account, it would seem proper to expose many
delicate tissues to the vapour of the chloroform before mounting in
balsam; or they may be preserved in the chloroform itself, although
it would be difficult, in such case, to find a proper cement for the
glass cover.




58                THE MICROSCOPIST.
best to make a thicker cell. This may be made by painting a
round or square ring on the slip with some sort of cement
which will not be acted upon by the fluid employed.-WVhite
lead worked with 1 part linseed oil and 3 of spirits of turpentine is well adapted for this purpose. —In this ring, the fluid
and object are placed and the cover put on.
Pieces are also cut off the ends of glass tubes and cemented
on the slips with marine glue, so as to form very neat cells. A
square piece of glass, with a hole drilled in it, cemented on
the slip, forms an excellent cell.  Such cells, ready prepared,
are imported and kept by McAllister & Co., Chestnut Street
above Second, Philadelphia; together with slips, thin glass for
covers, mounted preparations, a good variety of instruments
themselves, and other things interesting or useful to the microscopist.
Pieces of gutta percha tubes, cemented on to the slips by
heat, may sometimes be used for cells, and answer a good purpose. I have made excellent cells by using narrow slips of
glass for the sides, cementing them with marine glue.  They
are square, and are well suited for the larger class of objects.
CEMENTS.
Japanners' Gold-size, or Severe Dryer, is a mixture of boiled
linseed oil, dry red lead, litharge, copperas, gum  animi, and
turpentine. The first and last ingredients are its principal
constituents.  Mr. Williams, Artists' Furnishing Store, Sixth
Street above Market, Philadelphia, has it for sale.
Sealing-wax Varnish consists of small pieces of sealing-wax
dissolved in alcohol.
Asphaltum, dissolved in turpentine, has this advantage,
that spirit may be employed as the preserving, fluid if desired.
Marine Glue is a mixture of shell-lac, caoutchouc, and naph



MOUNTING AND  PRESERVING  OBJECTS.    59
tha.  It is melted by heat.  Caustic potash will remove its
traces from glass.
Gum MIastich and Caoutchouc, dissolved in chloroform, is an
excellent cement, and has the advantage of remaining fluid at
ordinary temperatures, while the rapid evaporation of the
chloroform enables the slide to be quickly prepared.
A solution of Canada balsam in ether or turpentine, evaporated to such a consistence that it can be laid on with a camnel'shair pencil, may be used like the last described, as a substitute
for marine glue.
Lampblack and white hard varnish, when laid on immediately, is a good cement.  Sealing-wax and white lead have
also been recommended.
For the thin glass covers, a mixture of the gum mastich
cement, above described, with asphaltum dissolved in turpentine, will be found very suitable.
MOUNTING IN BALSAM.
Before objects are mounted in Canada balsam they should
be perfectly clean and free from moisture. They are commonly
soaked in turpentine, especially opaque objects, as it renders
them more transparent. Grease may be removed by sulphuric
ether.
Very thin and transparent objects become indistinct in balsam; they should be made dark.  Vegetable matters may be
charred between two plates of glass over a lamp. Other
structures which cannot be charred, may be dyed by soaking
in a decoction of fustic or logwood, or a weak tincture of
iodine.
The balsam should be warmed on the slide to expel the air.
When objects of a cellular nature have to be mounted, if they
are such as heat will not much injure, they may be boiled in the




60               THE MICROSCOPIST.
balsam; otherwise numbers of air-bubbles will be left in the
cells, and the true structure cannot then be made out satisfactorily. The extra degree of heat will expand the air and
cause it to escape, and the balsam will take its place.
Some objects of a tubular nature, such as the tracheae of
insects, are better seen if air be contained in the tubes; they
will then exhibit the spiral fibre in their interior; but a tracheal tube filled with balsam does not show the fibre at all, the
balsam having made all the parts transparent.  Small insects,
such as fleas, and the parasites of animals, when not overheated, show the ramifications of the trachea, but those which
have been soaked long in turpentine, or have had the air expelled by heat, do not exhibit the spiral markings except under
polarized light.
When air is to be got rid of, the heat must be high; otherwise, the use of turpentine must be avoided, the heat of the
balsam kept low, and the mounting accomplished quickly.
The best way to heat the balsam on the slide is to place the
slide on a flat piece of iron, over a spirit-lamp; yet with careful
management a spirit-lamp will do alone.
Some persons keep their balsam in a tin vessel that can be
warmed so as to melt it. A drop of the fluid can then be
taken out and put on the object upon the slide. This plan is
attended with little or no risk of air-bubbles.  The cover
should be warmed on its under surface before it is laid on
the balsam, and if necessary, a small amount of heat applied
to the under side of the slide, to make the balsam flow more
readily.
When animal structures, such as parts of insects, or injections, have to be mounted, the heating of the balsam must be
carefully managed, and the balsam itself be very fluid to commence with.  It should be sufficiently warmed to expel all airbubbles, and, when nearly cold, the object should be placed




MOUNTING  AND  PRESERVING  OBJECTS.    61
in it and covered in the usual way.  By pursuing this plan
(for which, with many other suggestions, I am indebted to
Mr. Quekett's admirable work on the Microscope), I have succeeded in making some excellent preparations at the expense of
but little time and trouble.
If the heat applied to the slide be great, the object will be
sure to curl up, and bubbles will appear in all parts. It will
most likely be rendered useless, as no manipulation, however
carefully applied, will restore an overheated specimen of animal structure to its former beauty.
MOUNTING IN THE DRY WAY.
For objects which require a high magnifying power, they
may be placed on a slide and covered with thin glass, whose
edges may be touched with cement.  Objects which do not
require an object-glass of short focus, may be placed between
two slips of glass whose edges have been levelled so as to form
a groove, which may be filled up with cement or sealing-wax.
MOUNTING OPAQUE OBJECTS.
These must necessarily be viewed by light reflected in some
manner from their surface. Some transparent objects, however,
may be viewed as opaque ones by using the dark well or stop,
e, Fig. 16.  When mounted with this design they may be
placed on the slip of glass with a little gum-water, and surrounded with a rim  of card, paper, &c., sufficiently thick to
form  a proper cell, which may,be covered with thin glass.
Sometimes opaque objects are fixed on a round piece of black
paper stuck upon a slide.
a, Fig. 21, represents a disc of leather, felt, or other suitable
material, about three-eighths or half an inch in diameter, with a
6




62                 THE MICROSCOPIST.
pin passing through it.  The side for holding the object is to be
blackenedcl; the other side is covered with white paper on
Fig. 21.
which the name is written. b represents another plan, for very
minute objects; the pin is encased with blackened wax or
cement, or passes lengthwise through a small cork cylinder.!Fig. 22,
I///' II14.
Another method is seen at c, which consists of a small cylinder
of cork or felt with a pin passing transversely.  These must
be blackened with common lacquer (shell-lac dissolved in alco



MOUNTING  AND PRESERVING  OBJECTS.    63
hol) and lalnpblack, holding them  over a candle to dry.
Sometimes these cylinders are mlade of ivory, with the inside
turned hollow like a small box; the pin runs through them as
at c, and supports the object.  The ivory is dyed black and
the inner surface made as sombre as possible.  Mr. Quekett
reconnmmends to place the objects on pieces of cork glued to the
bottom, side, or cover, of small pill-boxes, as seen in Fig. 22.
Opaque objects should always be viewed with a black ground,
and the darker the object, the more sombre mlust be the
mounting.  White is, of all colours, the worst which can be
employed, unless the object is totally black.
MOUNTING CRYSTALS FOR POLARIZED LIGHT.
These must be so enclosed that the air is completely excluded, otherwise a change will take place, and the objects be
spoiled.  W~hen it can conveniently be dclone, it is well to
mount them in Canada balsam.  Sir David Brewster recommends mixing cold-drawn castor oil with the Canada balsam.
In this case the edges of the thin glass cover should be cemented, as the castor oil prevents the balsam. from becoming
hard.
Each preparation should be properly labelled, either with a
writing diamond on the glass slide, or on the paper cover of the
slide; and it may save trouble if this be invariably performed
as soon as imounted.




CHAPTER VI.
ON PROCUOJRING OBJECTS FOR THE MICROSCOPE.
THE topic suggested by the title of this chapter is almost
endless; for the microscopist may claim  contributions from
every department of natural science. The animal, vegetable,
and mineral kingdoms, all offer him interesting objects of investigation.  We shall content ourselves with noticing some
of the most important or attractive in each department.
I N O R G A N I C.
Agate.-This form of silica is often found imperfectly crystallized, and thin plates, prepared by the lapidary's wheel, -1-th
of an inch thick, exhibit a rich motley colouring when viewed
by polarized light.
Cacrbonate of Lime.-Small spherules of this substance are
sometimes found in the urinary deposits of the horse.  They
are often composed of concentric layers; at other times the
fibres are radial. Illuminated by polarized light under a power
of 100 diameters, they are splendid objects.
Crystaclization of Salts.-Independently of the beautiful
forms assumed by different salts during their crystallization, a
great variety of forms may be obtained by mixing small quantities of the different solutions in a little weak gelatine, starch,
mucus, &c. To procure specimens, put a drop or two of water,




PROCURING  OBJECTS.                      65
solution of gelatine, &c., upon a slide, put into it a drop of
some strong solution of salts, as Epsom salts, hydrochlorate of
ammonia, tartaric acid, &c.  Hold the slide over the spiritlamp until evaporation is perceived, when it should be removed
and placed under the microscope.  If the evaporation is too
rapid, the crystals will not be well formed.  They may be
mounted dry, or in balsam.  A  power of 30 diameters is
generally sufficient.  Crystals of salts form  interesting and
splendid objects under polarized light.
Ice.-A plan for observing the crystallization of water is as
follows.  Mis some water with a little charcoal, chalk, &c., in
such manner that a number of fine particles may be mechanically suspended in it; then take a glass slide, place it on a
cold night in an exposed situation, as outside of a window-sill;
pour upon it as much water as it will support without running
over the edge, and let it remain all night. The next morning,
if -the weather has been sufficiently cold, and the atmosphere
dry, neither water nor ice will be seen on the slide; but the
particles of charcoal will be found arranged in the various
forms which they assumed while the water crystallized.  The
slide may be carefully prepared with Canada balsaml for preservation.
Crystals of lI/on Pyrites, and other substances; Ooiites; and
various sorts of sand; are interesting objects.  The sand from
Turkey sponge, and friom the sea, often contains minute shells
of various kinds, as the foramin'ifera, &c., corallines, and other
zoophytes.
Sections of Gr.~anite, Limestone, &c., are also of considerable
interest; but sections of coal, made very thin, so as to be viewed
by transmitted light, develope clearly its vegetable origin, and
are therefore of special importance.
Deut-Iodunret of Mercury.-The change of colour in this salt
is a beautiful object.  If a little of it be placed in a watch6*




66                THE MICROSCOPIST.
glass, having another inverted over it, and then the lower one
heated over the flame of a spirit-lamp, the salt will be sublimed.  Placed on the stage of the microscope, with a power
of 30 diameters adjusted to focus at the inner surface of the
upper glass, minute crystals will be seen to form of a bright
yellow colour, which, as they cool, return to the original red.
VEGETABLE TISSUES.
Vegetable Tissutes are prepared by tearing, making thin sections, maceration in water, dissection, or are examined in their
natural state.
The spiral, dotted, and reticular vessels of plants require
generally to be dissected out, which is to be done under a
shallow magnifier. A single lens of one inch focus will answer very well for this purpose.  Having procured a piece of
asparagus, or the petiole of the garden rhubarb, &c., cut out a
piece about an inch long; split it open with a sharp knife or
scalpel, examine it under the magnifier, and separate with a
needle-point any of the vessels you require from the surrounding cellular tissue. This process is facilitated by dropping a
little water on the specimen. To prevent it moving, the specimen may be fixed with beeswax during the dissection.  Vessels, ducts, and cellular tissue, when prepared, should be kept
in spirits of wine until mounted.
tCuticles.-The external covering of plants, or cuticle, consists of a thin membrane, adherent to the cellular tissue beneath it. Under the microscope it appears traversed by lines
in various directions, giving its surface a reticulated appearance.  The form  of these reticulations varies in  different
plants: in some they are hexagonal, in others prismatic or




PROCURING  OBJECTS.                     67
irregular. Cuticles may be mounted dry or in fluid. The
geranium, oleander, &c., afford good specimens.
The cuticle of the under side of the leaf of many plants,
exhibits under the microscope dark spots among their reticulations.  These are called stomnata, and are the orifices by
which a function analogous to respiration in animals is effected.
They also serve for the exit of water from the plant by means
of evaporation. Plants destitute of stomata, as the South
American Cacti, &c., will remain in a hot and dry atmosphere
without losing their moisture.  The form, number, and arrangement of the stomata vary in different plants.
Cellular Tissue is the first and most generally developed
simple form of vegetable life. Its primary development may
be seen by examining a small portion of yeast at intervals
under the microscope. No plant is without cellular tissue,
and many are destitute of any other kind of tissue, as the
lichens, and some fresh-water algae. A section of the pith of
elder, pulp of peach, &c., will afford specimens.
The petals of flowers are mostly composed of cellular tissue; their brilliant colours arise from the fluid contained within the cellules. These form excellent microscopic objects, and
when mounted in balsam  are permanent.  The pelargoniums
and geraniums are among the most interesting.
The petal of the anagallis, or scarlet chickweed, is a beautiful object.  The spiral vessels diverging from the base, and
the singular little cellules which fringe the edge, are worthy
of notice.
Vascular Tissue, prepared by maceration and dissection,
presents many interesting subjects.  Spiral vessels consist of
membranous tubes with conical extremities, internally furnished with one or more spiral fibres.  As the vessels grow,
the spiral fibre breaks into short pieces, forming rings.  The
vessels are then called annular. If the pieces of fibre are still




68                 THE MICROSCOPIST.
shorter they are called dotted or reticulated vessels.  The root
of the garden rhubarb, the stemn of the hyacinth, the leek, &c.,
furnish examples.
A peculiar form of vessel is met with in the common carrot; it is obtained from the root in a layer between the yellow
central portion and the red annulus.
Sections of  fCood.-These are cut thin, so as to allow them
to be viewed as transparent objects.  IHard woods, containing
gum, resin, &c., should be soaked in essential oil, alcohol,
ether, &c., before mounting.  By transverse slices, a variety
of beautiful lace-like objects may be obtained, but little information is acquired from  them of the real structure of the wood.
For this purpose, if the tree is- of the endogenous and branchless kind —which grow by additions to the interior-a vertical
section is also necessary.  If the tree be an exogen, two vertical sections will be required in addition to a transverse one.
The exogens grow by annual layers exteriorly under the bark,
and are branched.  In these one of the vertical sections should
be radial and the other tangental.  The radial vertical section
will show the number and size of the medullary rays; that is,
the small portions of pith which proceed horizontally from the
centre, enclosed in a sheath of woody fibres.  The frecquency
and size of the medullary rays determine the number and
strength of the branches of the tree. This section also exhibits in coniferous trees (as the pine, &c.), the beautiful disclike glands which adhere to the woody fibres.  These are
beautiful objects, and sometimes require a power of 200 or 300
diameters.  The tangental vertical section is a slice across the
medullary rays; it exhibits the form  and arrangement of the
cellular tissue within them. All the vertical sections showthe
form, size, and connexion of the woody fibres; spiral, reticulated, and dotted vessels, &c.; and are far more instructive than
the transverse sections.




PRO  U RIN G OBJECTS.                   69
Chaarcoal.-Thin sections of charred wood are very interesting and instructive.
Fossil Woods.-Thin sections must be made by grinding on
a lapidary's wheel.  They should be polished.
Siliceous Cuticles, &c., from  equisetum, straw, cane, &c.,
are prepared by heat in a covered crucible, or by boiling and
digestion in nitric acid. The most favourable example for
showing the form in which silica occurs in plants, is the husk
of the oat or wheat.  If a husk of oat be examined under the
microscope, having been mounted in water or Canada balsam,
a series of bright parallel columns, serrated on each side, may
be observed among the cellular tissue: if another specimen be
burned carefully between the glasses, and the ashes be mounted in balsam, the siliceous columns will still be seen.  In the
ashes of the husk of wheat, rows of concave discs may be
observed, which are composed of some metallic oxide. In the
ashes of the calyx and pollen of the mallow, organized lime
may be detected. In the ashes of coal, a variety of vegetable
structures, as cellular tissue, spiral vessels, &c., may be discovered.  In these experiments it is necessary to render the
ashes transparent by immersion in balsam.
flai'rs,  Down, cc., from  leaves and stems, are generally
opaque objects. In the plants which produce cotton, the hairs
are attached to and envelope the seeds.  Hairs are composed
of cellular tissue. Their functions are said to be either lymphatic or secreting.  They offer great varieties in form, some
being stellated, others forked or branching.
Pollen may be mounted in Canada balsam; or, if rather
transparent, in fluid; or dry.  Sometimes the grains are interesting opaque objects.  The common form of the pollen or
farina of flowers is spherical, with a smooth, punctured, or
spiny surface; but some are square, others cylindrical, oval with
attenuated extremities, or triangular with convex sides.  The
pollen of the passion flower is very curious, and if immersed




70                THE  MICROSCOPIST.
in very diluted sulphuric acid opens and disperses the grains.
The pollen of Dac6'ra str'aon40ow'min?, or Jamestown weed, and
others, when immersed in a few drops of weak acid placed
upon a slide under. the microscope, emits a tube of some
length.  The granular matter in the pollen may then be seen
to pass along the tube until the pollen is emptied. The diameter
of the pollen varies considerably in different plants; among the
smallest are those of the Sensitive Plant.
Starch.- The granules of starch (not the ordinary impure
starch of the laundress) obtained from  different plants, are
found, when examined under the microscope, to differ in size
and form.  Solme are spherical, others elliptical, flask-shaped,
polyhedral, &c.  Hence this method of examination affords
a ready means of detecting fraud in the substitution of one
kind of grain for another.  Starch granules, although so very
mn3inute, are composed of a fine and delicate membrane, enclosing a fine mealy powder.  It may be compared in some respects to a common pea, in which the legumen is enclosed in
a testa or skin.  Starch granules are not soluble in cold water,
nor is iodine capable of acting on them while the membrane
enclosing its contents remains whole. If the granules be triturated or inmmersed in hot water, the membrane will be ruptured,
and iodine will then turn them blue.  Starch is readily separated from wheat, potato, arrow-root, &c., by repeated washings
in cold water.  To obtain it from  rice, the grains should be
macerated for a few days, and to prevent the decomposition of
the gluten, a little soda should be added to the macerating
water.  Under the microscope, the surface of starch-grains
often appears corrugated, and each of them  has one or two
bright spots, called the hilum, which is supposed to be the
part where the starch adheres to the cell.  Under polarized
light they present the beautiful phenomenon of the black
cross.  They should be mounted dry, and protected from the
pressure of the upper glass by a rim of thin paper.




PROCURING  OBJECTS.                      71
Seecds are generally opaque objects, and present a great
variety of beautiful and interesting forms.
ftcctd Tissues, the stones and shells of nuts, &c., are prepared like bone, &c., by cutting and grinding.  Some require
the lapidary's wheel.
tRclhicles, or crystals from  the interior of plants.  If the
leaf or bulb of a common hyacinth be wounded, a discharge of
fluid ensues; if this be received on a slide and submitted to
the microscope, a number of minute acicular bodies will be
observed floating in the liquid.  They are called raphides.
They are common in many plants.  By scraping hickory, or
other bark, on to a slide, moistening it with the breath, and
blowing off the woody particles; or by placing a part of the
ashes of a burnt maple leaf, coat of an onion, &c., on a slide,
such crystals may be seen.  They may be mounted dry or in
balsam.
Jlfosses, are supposed to be destitute of woody fibre and vascular tissue.  When a leaf is carefully examined, the septa
which divide the cells are sometimes found to take a spiral
course.  To observe this structure, soak the moss in water, to
expand the cells.
It is essential, in collecting mosses, to preserve the thece, or
seed-vessel, for without it the genera cannot be determinedcl;
while this part, with the calyptra and operculum, are the most
valuable for the microscope.
Agyw.-Are interesting objects.  The green, muLous, slimelike matter in damp garden walks, and the hair-like weeds in
ditches, are examples of fresh-water algae. The sea-weeds of
our coast are marine algw, and are often found having zoophytes adhering to them; they are then splendid opaque objects.  For mounting in balsanm, the smaller kinds, of a bright
scarlet colour, are the most valuable.
Ferns.-The genera are mainly distinguished by the position and arrangement of the organs of reproduction.  These




72                TH E MICROSCOPIST.
are mostly on the under side, or along the margin of the leaf
or frond.  They are best examined as opaque objects.  They
should be collected before they are quite ripe.  The spores
(seeds) are usually enclosed in brown capsules, each having
an elastic ring about its equator, which when ripe bursts, and
the spores are dispersed to a distance. Spores may be mounted
either as transparent or opaque objects.  The development of
ferns may be observed by placing the spores in moistened
flannel and keeping it at a warm temperature. At first a single
cellule is produced, then a second, and so on. After this the
first cellule divides into two, and then the others, by which a
lateral increase takes place.
Lichens and Fungi afford interesting objects.  The various
kinds of mildew  upon vegetable substances are familiar examples of minute fungi.
Organic FcTbrics possess much interest in a commercial
point of view, in addition to the curiosity arising from the
manner in which the threads or bundles of fibres are woven or
interlaced. For this purpose they should be examined as
opaque objects on a black ground, with a magnifying power
of from 30 to 60 diameters.  The fibres of cotton are readily
distinguished under the microscope from those of linen, wool,
&c. Cotton fibres are tubular, and are fornned of pure cellular
tissue. These tubes, from the thinness of their sides, often
collapse and appear like fiat ribbons or bands. The reason
assigned for the preference given to linen (flax) over cotton
for lint, for surgical purposes, is that the fibres of the former
are solid cylinders of woody fibre, while the edges of the
flattened bands of the latter are supposed to irritate the
wounds.
Circulation in  Vegetables.-The circulation in plants, termed
cyclosis, is a revolution of the fluid contained in each cellule,
and is distinct from those surrounding it.  It can be observed
in all plants in which the circulating fluid contains particles of




PROCURING  OBJECTS.                     73
a different refractive power or intensity, and the cellules are of
sufficient size and transparency.  Hence all lactescent plants,
or those having a milky juice, with the other conditions, exhibit this phenomenon.  The following aquatic plants are
generally transparent enough to show the circulation in every
part of them: —  tella hyal7ina, Nitellct translucens, Ccharc6
vulzgatris, and Caulinica facgilis. In the Frogbit (Hyclrocharis),
it is best seen in the scales surrounding the leaf-buds, with a
power between 60 and 200 diameters.
The jointed hairs of the filament of the anther in Tranclescantica virgiqnica (Spiderwort); the delicate hairs on the leafstalk of Senzecio vulgaris (Groundsel); and a section of the
leaf of Vallisnerica spiralis, will show the circulation, especially
when viewed with a high power.
ANIMAL TISSUE5S  ETC.
INFisOORIA.-These minute animals, some of which are
only the 251000th part of an inch in diameter, are extremely
numerous.  Between  700  and 800 different species have
been discovered and described.  Dr. Ehrenberg, to whom we
are indebted for much of our knowledge respecting the animalcule, divides them into two classes, i. e., Polygastrica and
Rotatoria.  The first class is so named from their possessing a
digestive apparatus composed of many globular vesicles, which
perform  the functions of stomachs.  The Rotatoria are so
called from their possessing rotary organs about their mouth.
These are much more highly organized than the others.  The
Polygastrica increase by self-division, or by the growth of
gemmules or buds upon their bodies; the IRotatoria are hermaphrodite, and oviparous.  Many animalculh  are loricated; or
protected by a shell, or shield, which is generally siliceous:
others are destitute of such an appendage.
7




74                      THE MICROSCOPIST.
The following  table  exhibits  the  families  or  groups into
which this interesting department of animal life has been divided by  Ehrenberg.   Those  who wish  further information  respecting  them   are  referred  to his work  "Die Infusionsthierchen,"  or to  Pritchard's  " History  of Infusoria, Living  and
Fossil."   Dr. Mantell's  work  on  Animalcules  contains also
much valuable information.
CLASS I. POLYGASTRICA.
Selfclivisn   illoricated or shell-less, Blonadina.
complete loricated or shelled,    Cryptomonadina.
Bod    y            /complete.
c    Bocdy
destitute of    Form    self-divi-  (self-dividing on all
C-  appendages.  of body ( sion in-    sides (globular),
s   (No foot-like e  constant.  complete,  self-dividing tilloricated Vibriona
processes.)                 hence    unilateally.
lence    unilaterally      1oricated, Closterina.
Gpymneica.  |             formed in  (filiform).
clusters. L
Form..
For      illooricated, cated               Astasiaea.
of body
o x          variable.  loricated,..           Dinobryina.
Fo                    f illoricated,                            Amoebaea.
Foot-like processes I            (compound foot-like process  Arcellina.
variable.       loricated  from one aperture,
o Pseudo-poda.  I' simple foot-like process from   Bacillaria.
one or from each aperture,
Hairy    (   illoricated,                             Cyclinida.
T   El~tricha.     loricated,                                Peridinaea.
One receiving and f
4  dischargingorifice  illoricated,                              Vorticellina.
g  only for nutrition.  loricated, -                            Ophrydina.
c lzopisthia.    [
Two ditto orifices, 
one at each     illoricated,.                 Enchelia.
extremity.         loricated,..- Colepina.
/ Enantritenza.   [
mouth furnished with pro]     oblique.        rieated} boscis, tail absent,
- A' lloreta.iaed.     mouth anterior, tail present, Ophryocercina.
[ loricated,  --- Aspidiscina.
N   Orifices abdo   oricat-   locomotive organs cilii,     Kolpodea.
nal.       illoricate      do.     do.  various,   Oxytrichina.
Catotreta.     loricated,.               Euplota.




PROCURING OBJECTS.                              75
CLASS II. ROTATORIA.
With a simple con- [margin of cilii-wreath entire.   illoricated, Icthydina.
tinuous wreath of             esHolotrocha.     loricated, Oecistina.
cliii.      margin of cilii-wireath lobed or{ illoricated, Megalotrochaea.
onotroc7ia.)   Scotchds.      loricated, Floscularia.
(with the cilii-wreath divided into illoricated, Hydatinea.
With a compound           several series.       loricated, Euehlanidota.
or divided wreath of I      Polytrocha.
cilii.      - with the cilii-wreath divided into illoricated, Philodinaea.
(Ssrs.)ZygI otrocha se.       loricated, Brachionaea.
In  reference to obtaining  infusoria, some persons imagine
that if they  procure a portion of fetid  ditch-water, or take
a few flowers, &c., and macerate them  in water, they will be
furnished in a few days with all the varieties they may desire;
but this is not the case.  Infusoria will of course be found,
but they will be only of the most ordinary kinds.  To obtain
those of higher interest, some degree of skill is required.
MIany remarkable species have been taken in mleadow-trenches
in the slowly running water, after a summer shower, especially
about the time that the first crop of hay was mown.  Among
healthy water-plants, the various kinds of Vorticellina (Stemntors and Forticells, or trumpet and bell-shaped infusoria), and
Rotatoria (wheel-animalcules), may be sought for with success.
The stems of aquatic plants have often the appearance, to the
naked eye, of being encased with mouldiness, or Enrucor, which
on being examined with the microscope, proves to be an extensive  colony  of  arborescent animalcules.   The  dust-like
stratum   sometimes  seen  on  the  surface of ponds, and  the
shining film  which sometimes covers water-plants, assuming
various hues of red, brown, yellow, green, and blue, is caused
by the presence of infusoria, some of which are very beautiful.
Many species live in the clean fresh water of rivers, lakes, and
springs; and the brine of the ocean, likewise, as well as the




76               THE MI0RpOSCOPIST.
mould on the surface of the earth, has its microscopic inhabitants.
In order to procure animalcule, provide yourself with a
number of clean, wide-mouthed, glass phials, fitted with proper
corks, not glass stoppers, so that the air may have access to
them, at least to some extent.  Have also a rod, or walkingcane, which may be prepared with a spring-hook and ferule for
fastening a phial on its end, although a piece of twine is a
good substitute.  On reaching the pond, &c., carry the phial
(attached to the rod) in an inverted position, and when at
proper depth, or in the neighbourhood of water-plants, it should
be turned quickly, when anilnalculic, &c., will run into it.
Water-fleas and Daphniae should be frightened away by shaking the phial before turning. If in the phial, they go quickly
to the bottom, and the upper water can be poured off. Examine the water with a pocket lens, and preserve the animalcu le.
The indications of the presence of infusoria are specks moving about in the water, or an apparent imouldiness around the
stalks of the water-plants, &c., which may have been caught
in the phial.  If these appearances be not discerned by the
magnifier, the water may be thrown away, and another place
resorted to.  A small portion only of vegetable matter should
be preserved in the phial, as its decay may soon kill the animalcules.
Small newts and many larva should be preserved; the former especially, as they eat up the [Daphnie, MIonoculi, &c.,
that destroy the Vorticellke. In the branchise of young newts,
too, and in their feet, the circulation of the blood is beautifully
seen.
The phial should sometimes be laid horizontally on the bottom of the pond, and scrape the surface of the mud.  This
should be put in a large jar with water, and in a day or two




PROCURING  OBJECTS.                     77
the animalculse will be on the surface of the mud, from which
they can be removed with the fishing-tubes (see page 47), and
placed under the microscope.
If the creatures are too minute to be seen easily with the
naked eye, pour a little water from the vessel containing them
into a watch-glass, and place it on a piece of cardl-board, rendered half black and half white. The white ground will make
the dark specimens apparent, and vice versa.  They can then
be seen with the pocket lens, and taken out with the fishingtubes.
In order to show the stomachs, cilia, &c., of animalcuhle
under the microscope, rub some pure sap-green or carmline on
a palette or plate of glass, and add a few drops of water. If
the glass be now held on one side, a portion of the colouring
matter may be put into the water on the slide containing the
animalculhe. If they be vorticell-e or rotiferoe, the particles of
colouring matter will show the vibratile actions of the cilia,
whilst other particles, swallowed by the animals, will give a
rich tint to the compartments of their alimentary canal.
_Fossil Infusoria.-A great number of infusorial earths may
be mounted in balsam  (test objects dry, however,) without
washing, &c., but others must be repeatedly washed or digested
in acid. For the skeletons or shields in carbonate of lime, Professor Ehrenberg has directed to place a drop of water on the
slide, and put into it as much scraped chalk as will cover the
fine point of a knife, spreading it out, and leaving it to rest a
few seconds; then withdraw the finest particles, which are
suspended in the water, together with most of the water, and
let the remainder become perfectly dry. Cover this with
Canada balsam, and hold it over a lamp until it becomes slightly fluid, without froth.
Siliceous Shields of ]izfusorict, such as those in guano,
Richmond earth, &c., require to be well washed, and boiled or
7*




78                THE  MICROSCOPIST.
digested in nitric or hydrochloric acid.  After this, a small
quantity of the sediment in which they are contained should
be placed on a number of slides, and those containing the best
specimens laid aside for mounting.
Sponges.-These lowly-organized bodies are found both in
salt and fresh water in all parts of the globe.  Many of them
are very minute, and may be examined without much preparation, but others require to be burned, or acted on by acid,
to show the small masses of flint, called spicula, which form
their rudimentary skeleton, as well as other masses of the
same material, which enter largely into the framework of the
young sponges or gemmules.
Corals are best examined by horizontal and vertical sections. If the animal matter only is required, the sections may
be macerated in hydrochloric acid, to which five or six times
its bulk of water has been added.
Zoo2hy/tes.-lResidents at the sea-sile, or occasional visitors,
when provided with a microscope, have frequent opportunities
of examining some of these most elegant of animal forms.
Scarcely a piece of sea-weed or fragment of shell will be
found, that does not afford a habitation for soime member
of this interesting family.  The animals are generally found
in clusters, or compound, sometimes comlllunicating at a coinmon centre; at other times distinct and only connected by
the solid matter of which their polypidoms are formed. Some
few, as the common fresh-water polype, do not secrete any
hard substance either around or within them.
INSECTS.-These afford the most numerous and beautiful
objects for examination, as there is scarcely a part of the body
of an insect that does not exhibit some remarkable structure.
Antenna.-The horns of insects not only vary in form in
different genera, but in the male and female of the same
species. They may be mounted as opaque, or in Canada
balsam.




PROCURING  OBJECTS.                     79
Eggs.-The eggs of insects are generally of an oval form,
the outer covering being sufficiently rigid to resist ordinary
external impressions; others are, however, soft and pliant. In
some species they are globose, as in many Lepidoptera; or
conical, as in the large white cabbage-butterfly; cylindrical,
pear-shaped, barrel-shaped, &c.  They are for the most part
smooth; but many are very beautiful, ornamented with symmetrical ridges, canals, dots, &c., giving them, as Reaumer observed, the appearance of embossed buttons.  Some are furnished with appendages for peculiar purposes.  Thus the eggs
of the dung-fly (Scatophagcc  ittPris) has two obliqcue props at
one end, to prevent it sinking too deep in the matter upon
which it is deposited, while those of the water-scorpion (Nepa
cizcerea) are furnished with a coronet of spines, forming a receptacle for the egg which is deposited immediately afterwards.  Sometimes, one end of the egg is provided with a
sort of cap or lid; at other times the egg is in one piece, and
the enclosed larva must gnlaw or burst through it.  The colour
is very various, although white, yellow, and green are the
most prevalent tints.
In many species the eggs are deposited singly; in others,
they are discharged en mcasse.  Somen arrange them  symme.
trically, and others enclose them  in a mass of gluten, especially those whose larvT inhabit the water. Many species employ a gummy matter to attach them firmly to the substances
on which they are placed; while some, as the yellow-tail moth
(Arctia chrlysorrlicea), wrap them in a coating of down, which
they pull off their own bodies; and the lackey moth (Lasioca2npa \c eustria), deposits her eggs in a spiral coil round the
stellas of fruit trees.
Most varieties require to be viewed as opaque objects under
a power of 30 to 60 diameters.
Elytra, or wing-cases of insects, are often singularly engraved and coloured, and form the most brilliant of all opaque




80                THE  MTICROSCOPIST.
objects.  Some are covered with beautiful iridescent scales,
and others are furnishecd with branched hairs.  Some of them
are much improved by being mounted in a thick cell with
Canada balsam, while others lose much of their splendour by
being so treated.  In order to ascertain whether an elytron
will be improved by the balsam, one of the legs, or some part
supplied with a few of the iridescent scales, should be touched
with turpentine; if the brilliancy be increased, it may be
mounted in balsam, if otherwise, dry.  The elytra of some
beetles, after having been softened in caustic potash, may be
mounted between flat glasses, as ordinary objects.
Eyes of Insects, Arachrnidcl, &c.-The structure, number,
and form of the eyes of insects may be ranked among the
most curious parts of natural history.  They are generally
hemispherical, on each side of the head, but sometimes they
are oval or kidney-shaped.  When closely examined, they are
found to consist of a vast number of minute lenses, generally
hexagonal, but sometimes quadrangular or circular.  In the
ant there are 50 of such lenses in each eye; in the common
house-fly 4000; in the dragon-fly 12,500; and, according to
Geoffroy, in the eye of a butterfly 34,650.  When one of the
eyes is detached -from  the head and cleaned, the lenses are
found to be as clear as crystal.  If a cluster of eyes be placed
under the microscope, at a distance without its focus equal to
their focal length, the lens of each eye will exhibit a distinct
image of a candle, &c., placed before it.
The external form of the eye may be seen in situ in all insects when viewed as opaque objects, but the layer of lenses
requires the aid of maceration and dissection to free them
from a considerable amount of pigment.  They may then be
mounted dry, in fluid, or in balsam.  If required to be flat,
they must be made so by pressure while soft, otherwise they
are liable to split.




PROCURING  OBJECTS.                     81
If the eye of a fly, or other insect, properly prepared by
mounting in balsam, be held near the eye of an observer who
looks through it at a distant candle, &c., the interference of
light in the minute lenses will cause a number of images to be
perceived, tinged with beautiful colours.
The eyes of spiders are single.  They have from  four to
twelve, variously arranged.  Some insects have also single
eyes in addition to the compound eyes before noticed.
Feet. —The structure of the feet of those insects which support themselves on polished surfaces, and against the force oi
gravity, is very remarkable, and it is doubtful if it be yet perfectly understood.  Some suppose them to act as suction-pads,
others that they secrete a viscid fluid by means of which they
stick with sufficient force to enable them to walk.  The latter
theory is rendered most probable by microscopic researches.
The number of pads on each foot is variable.
The anterior and middle pairs of feet of the male Dytiscus
are furnished with curious disc or cup-shaped appendages on
the inside of the leg.  They may be viewed as opaque and in
balsam.
Hrutes of Insects, &c., may be mounted dry, in fluid, or in
balsam. In some spiders the hairs are branched; in the larve
of many insects they are covered with spines, as the hairs of
caterpillars, &c.; and in the crustacea they are provided with
spines, or plumed like a feather. The hairs and scales of insects will be further treated of in the chapter on Test Objects.
Heads, Mlfouths, &c.-The manducatory apparatus of insects
is a subject of great interest to the entomologist.  The division of insects into Mandibulata and H-austellata are founded
thereon; the first having jaws, the latter a proboscis or sucking instrument.  Some of them require but little preparation,
and may be mounted as opaque objects; others, as the probosces and lancets of flies and bees, demand considerable skill




82                THIE  MICROSCOPIST.
to display them to the best advantage.  When thin and transparent, they should be mounted in fluid, but if thick and opaque,
in balsam. Before mounting in the latter way, they should be
dissected while soft, and laid out on a slide to dry.
Pcarasitic Insects should be placed in spirit and water in
order to kill them.  They may be mounted in fluid or balsam.
Some of the large kinds may be examined as opaque objects.
The term Epizoa has been applied to them because occurring
on the exterior, in contradistinction to those occurring within
animals, which are called Entozoa.  Some of them are classed
with insects, as having six legs; while others, having eight, are
called Acari, and are included in the class Arachnida.
Some very minute insects, called Aphides, are abundant on
plants, the leaves, &c., of which they destroy.  Others, called
Cynips, are the cause of the excrescences on the leaves, &c.,
of trees, termed galls.  The well-known oak-apple is produced
by the CKzynis qutercus, which is a most elegant object when
examined by reflected light.  The same may also be said of
the insect from  the gall of the rose.  Gather the galls when
ripe, and place them in a box covered with gauze.  In a few
days or weeks numbers of insects will escape from  the gall,
and those exhibiting beautiful colours may be selected.
Among the Acari, may be mentioned the cheese-mite, A.
dogesticus, and the itch-insect, A. sccbiei.  To obtain the
latter, the operator must examine carefully the parts surrounding each pustule, and he will generally find in the early stage
of the disease, a red spot or line communicating with it; this
part, and not the pustule, must be probed, and the insect, if
present, be turned out.  It is often, however, difficult to detect its haunts.
To obtain the Entozoo  jfollicudorumn, which is a parasite
occurring in the sebaceous follicles of the skin of the forehead,
nose, &c., squeeze the neighbourhood of the little black spot




PROCURING  OBJECTS.                      83
or pustule, so as to force out the sebaceous or oily matter.
This should be laid on a slide, and a small quantity of oil
added to separate the insects fronm the nidus in which they are
imbedded.  They may then be transferred by a pencil-brush
to a clean slide, covered with thin glass and mounted.
Another species of Acarus, the harvest-bug or tick, A. antumnnalis, is a very painful source of irritation to the skin
wherein they may have insiluated themselves.  They may be
dislodged with a needle, and mounted in fluid or balsam.
Tracheac ancd  Spiracles of Insects.-The respiratory system
of insects will be described in the chapter on Dissections, together with their nervous, digestive, and circulatory systems.
The manner of mlounting them is alluded to on page 60.
Stings, Ovijositors, &c., frequently require considerable care
in dissection.  They may be -mounted in fluid or balsam.
SI-HELLS OF'IOLLUsA.-The structure of shell has only
lately attracted the attention of microscopists, but since the
year 1842 the subject has been scientifically investigated by
Mr. Bowerbank and Dr. Carpenter.  According to the experiments of the latter gentleman, undertaken at the request and
expense of the British Association, the calcareous matter in
all shells is nearly equally crystalline in its aggregation, and
the particular forms which their fracture presents are determined chiefly, though not entirely, by the arrangement of the
animal basis of the shell, which possesses a more or less
highly-organized structure.
All thin  sections of recent shell are translucent, except
when the colouring matter is opaque, or when the calcareous
matter is deposited in a chalky state between the true laminve
of the shell, as in the oyster.
Dr. Carpenter classifies shells, into-1. Prismatic cellular
structure, as exemplified in the Pinn;w.  2. M3embranous shell
substance, as the J/yca, Anatina, and Thraciac.  3. Nacreous




84                 THE  MICROSCOPIST.
or pearl structure, as the inner surface of some species of
Ostrea and MJtilus.  4. Tubular structure, as the outer layer
of Anomia Ephifpimrn, Lima scabra, &c.  In some cases the
tubes run.at a distance from each other obliquely through the
shell, as in Area Now.  5. Cancellated structure.  Examples
of this latter division, which somewhat resemble the cancelli
of bone, are only imet with in certain fossil shells.
Shell should be examined microscopically in three ways: by
reflected, transmitted, and polarized light.  For the first, fragments of shell will suffice; for the others, thin sections, cut
both vertically and transversely, are necessary. To exhibit the
animal basis of shell, specimens may be treated in the manner
recommended for coral.
ScALEs  or FIsI.-M. Agassiz has arranged the class of
fishes into four orders, according to the structure of their
covering, as follows:
E/cnamelled Scales.
1. Placoidclans. Cartilaginous fishes, having prickly or flattened spines, as the skates, dog-fish, and sharks.
2. Ganoidians. TWith angular scales composed of horny or
bony plates covered with enamel, as the sturgeon, and bony
pike.  Fifty out of sixty genera are extinct.
Scales not Enaimelled.
3. Utenoidians. Scales notched or serrated on their posterior
free edges, as the perch.
4. Cycloid  fishes, with smooth scales, more or less circular,
and laminatedl, as the herring, salmon, &c.
Among the various kinds of fish-scales selected for microscopic objects, those of the eel are much prized, as it was formerly considered that it had no scales.  They may be obtained




PROCURING  OBJECTS.                    85
from the under surface of the skin with a knife or a pair of
forceps.
Some scales when viewed by polarized light have a brilliant
effect. They may be mounted in balsam. Fossil scales, as well
as others, may be examined as opaque objects.
HAIR OF ANIMALS, &c. —Hairs are composed of an aggregation of epithelium cells, and the colour depends upon the
quantity of pigment deposited in or about each cell.  Care
should be taken to select both the hair and the wool from each
animal, as they differ materially in their structure; the finer
kind, or what is known as wool, being endued with the property termled felting, which property is of considerable importance in a manufacturing point of view.
The felting property is owing to the imbricated scales on
the outside of each hair. In the adult human hair this structure is not very apparent, but may frequently be seen in fine
specimens from very young infants. These, however, should
not be mounted in balsam.
The smaller kind of hair may be mounted dry or in fluid;
or, if of a dark colour, in balsam.  Horizontal and vertical
sections should be made of large hairs and spines, which may
be done after gluing a number together, in the samle way that
sections of wood, &c., are made.
Sections of horns, hoofs, quills, whalebone, spines of echini,
&C., are all interesting objects.
ANATOMICAL OBJECTS AND PREPARATIONS.
BLOOD.-To examine this vital fluid, it is necessary to place
upon a glass slide a small drop recently taken, and cover it
with a thin glass or piece of mica.  The blood corpuscles may
also be preserved in Dr. Goadby's A 2 fluid, or prepared by
8




86                THE MICROSCOPIST.
drying rapidly on the slide and covering with the thinnest
glass.
The red corpuscles in man are of a circular flattened form.
If water be added to them, they become spherical by endosmose.  Their appearance varies as they are viewed a little in
or out of the focus of the microscope; in one place showing a
nucleus or spot in the centre, and in the other a thickened
edge, like a ring.  In all air-breathing, oviparous, vertebrated
animals, the blood corpuscles are oval, and a nucleus may be
observed within each of them.  This nucleus is rendered very
distinct by the addition of a drop of diluted acetic acid.
The observations of Professor Owen on the blood-discs of
the bSiren lacerticna show that the nucleus consists of a cluster
of nucleoli enclosed in a capsule in the centre of the oval
bloocd-disc.  The length of the disc in the Siren is 4j-,th of
an inch, while the diameter of human blood-discs average
Io th of an inch.
Circulation of Blood may be seen in the web of a frog's
foot (see page 46); in the fin or tail of a fish; and in the legs,
&c., of many spiders and insects, especially acquatic  larvm.
There is nothing so wonderful and pleasing as the sight of the
blood corpuscles coursing through the vessels in the web of a
frog's foot, when seen with a power of about 200 diameters.
The researches of Kaltenbrunner; a distinguished German pathologist; on the circulation of blood in a frog's foot, and the
influence of various irritants upon it, as seen under the microscope; have added much to our knowledge respecting congestion and inflammation, and are of the highest interest to the
practitioner and student of medicine.  They are referred to by
Dr. Watson in his preliminary lectures on the Practice of
Medicine, and their importance clearly shown.
BONE should be cut into thin sections, about Joth of an
inch in thickness.  They can be cut with a fine saw, such as




PROCURING  OBJECTS.                     87
are made of watchspring.  They should then be cemented on
a piece of glass; filed to the proper thinness; ground upon a
hone; and polished by a leather strap or piece of cloth charged
with putty powder (oxide of tin and lead), or carbonate of iron
(rouge).  They may be mounted dry or in balsam.  Both
transverse and longitudinal sections should be omade.
When animal tissues are consolidated by the deposition of
earthy matter within their cells and fibres, a hard, solid substance is produced.  Sometimes the earthy matter crystallizes,
as in the teeth; at other times it combines chemically with
the gelatine of the cells, as in bone.  This deposition in bone
does not occur in all the cells, as the bone requires to grow
and be nourished; hence arises its peculiarity of structure.
Independently of the hollows, or cancelli, the hard part of
the bone is traversed by canals, called Haversian, which run
in the direction of the lamint; these are connected by transverse communications.  In a thin transverse section of bone,
the solid matter may be observed arranged around the Haversian canals in concentric rows.  Amnong these layers dark
specks are dispersed.  These dark specks (called lacmnw; or
coirpuscles of Puckidje), when magnified about 200 diameters,
are observed to be cavities of an irregular, oval form, from
which emanate numerous minute branch canals.  These cavities appear dark for the same reason as a minute air-bubble
does in Canada balsam-lnamely, the difference of refraction of
the two media.  By means of these branches (canamicvfi),
lacunmi, and Haversian canals, the bone is nourished with
proper fluids.
It has been shown by Mr. J. Quekett, that there are differences in the form and size of the lacunm, in the various classes
of animals, sufficiently characteristic to allow of the assignment
of miinute fragments of bone, with the aid of the microscope,
to their proper class.  The lacune of reptiles are distinguish



88                THE  M1ICROSCOPIST.
able by their large size, and long oval form; and those of fish,
by their angular form and the fewness of their radiating canaliculi.  The lacunue of the bird may be distinguished from
those of the malnmmal, partly by their smaller size, but chiefly
by the remarkable tortuosity of their canaliculi.  It is worthy
of remark, also, that the sizes of the lacuna in the four classes
of vertebrata, bear a close relation to the sizes of their blood
corpuscles.
SECTIONS Or TEETH may be made in the same way as bone.
Some should be soaked in hydrochloric acid, to destroy the
earthy matter, and others in caustic potash, to get rid of animal
matter.  These should be mounted in fluid, the others dry, or
in balsam.
A tooth consists of three distinct structures, the relative proportions and arrangement of which constitute the chief differences in the teeth of various animals.  1. Enamel.  This is
crystallized phosphate of lime, deposited in the form of long
prisms, each about S-O th of an inch in diameter, produced in
animal cells, which are almost obliterated when the tooth is
fully formed.  In human teeth a coating of enamel is formed
over the crown of each.  In the teeth of some animals the
enamel is disposed in vertical layers among the other structures of the tooth.  This is especially the case with the grindcling teeth of large herbivorous animals.  2. Dentine, or Ivory.
This forms the principal substance of which the teeth are composed.  The amount of animal gelatine in it is often very
considerable. The earthy matter is usually deposited in the
form of fine branching cylindrical tubuli, radiating from  the
centre of the tooth.  These tubules have been successfully
injected with colouring matter by Dr. White, of Philadelphia.
On the ends of the dentine tubuli are placed the ends of the
enamel prisms, in the human tooth. Dentine is now established
by Professor Owen as an ossification of the pulp of the tooth.




PROCURING  OBJECTS.                     89
3. The Bone or Cemnentunm, of, teeth, is composed of a mass
of earthy matter and cartilage, having minute cavities or bone
corpuscles and calcigerous canals.
Sometimes a vertical section is made of a tooth?in situ, exhibiting a section of the jaw with its cavities for the nerves
and vessels, as also the manner in which the alveolar process
which forms the socket is constructed. Both vertical and transverse sections should be made.
SKIN.-In some animals, as fish, the skin is not very vascular, while in the mammalia, and, perhaps, in the human subject,
it attains the highest state of organization. The skin performs
a function in the animal economy second only in importance
to that of the lungs, and for the purpose is supplied with a
very rich capillary network; and also provided with two or
more sets of glands, one for secreting the perspiratory fluid,
the other an unctuous or sebaceous matter for lubricating the
skin itself.  Taking the human skin as an example, we should
commence the study with vertical sections, made through parts
supplied both with hair and papille.  The perspiratory glands
are best seen in the soles of the feet, and palms of the hands;
the sebaceous glands should be examined in parts about the
face or chest, where hairs are numerous; these latter sections
will also show the roots of tlie hairs and the hair follicles.
The skin may be rendered firm enough for vertical section by
hardening in a saturated solution of carbonate of potash or in
strong nitric acid.  The capillary network of the cutis vera
may be seen in injected specimens when the cuticle has been
removed, which will often require the aid of maceration for
the purpose.  If the skin be that of a black man, care should
be taken in the removal of the cuticle, as in it may be examined the rete mucosum, or coloured layer, which consists of
a series of minute hexagonal cells, containing pigment.  The
same structure may be seen in the skins of animals whose
8*




90                THE MICROSCOPIST.
hairs are black; for this purpose the lips of a black kitten,
when injected, should be selected, as in them  the mode of
growth of the young whiskers, their copious supply of bloodvessels and nerves, and various other points of interest, may
be observed. The papillae are best shown in the extremities of
the fingers and toes, when injected; the cuticle which invests
them should also be mounted as an object, with its attached or
papillary surface uppermost, as in this the grooves for their
lodgment, together with the openings of the sudoriferous
glands, can be well seen.
EYEs.-Many objects of interest may be obtained from the
eyes of various animals; as the crystalline lens, the pigment,
the ciliary processes, the retina, and the membrane of Jacob.
The structure of the crystalline lens in fish is best seen after
the lens itself has been hardened by drying, boiling, or long
maceration in spirit.  After having peeled off the outside, the
more dense interior will be found to split up into concentric
lamina, and each lamina will also be found to be composed of
an aggregation of toothed fibres; these are best seen when
mounted in fluid, but if dyed, they] will show very well'in
balsam.  The pigment is easily obtained by opening a fresh
eye under water. It umay then be detached as a separate layer,
and parts of it floated on slides to dry, after which they may
be mounted in balsam. The ciliary processes are best seen
when injected; they should be mounted in a convenient cell
with fluid, and viewed as opaque objects.  The retina should
be examined from  a very fresh eye, between glasses, and a
little serum or aqueous humour addedl, to allow the parts to
be well displayed; but water must be avoided, as the nervous
matter will be considerably altered by it; the membrane of
Jacob will also require the same precautions, but the vascular
layer of the retina, when injected, may be well seen after
having been dried.




PROCURING OBJECTS.                      91
MUSCULAR FIBRE.-3Muscles are of two kinds, voluntary
and involuntary; from their functions. The voluntary muscles
of all the vertebrata, and the articulate animals (as insects,
&c.), have their fibres marked with transverse strive.  The involuntary muscles are not so marked.  These marks are supposed to point out the ultimate corpuscles or cells of which
the fibrillse are composed. The general opinion is, that the
juxtaposition of cells is the true form of the ultimate fibre.
Several microscopists, however, of some note, believe the fibre
to be spiral, and enclosed in a membranous sheath.  In my
own examinations I have met with cases where the structure
appeared to be a bead-like fibre wound spirally into a tube, or
around a central unmarked fibre; yet other observations, especially with polarized light, show a longitudinal arrangement of
cells. Perhaps the true structure is a compound of both these
modes; the sheath being spiral, and the ultimate fibre longitudinal.
A small portion of muscle, freed from  cellular tissue, may
be put on a slide with some kind of fluid, placed under the dissecting microscope, and the fibres torn asunder with fine needles.
It should be preserved in fluid under a thin glass cover.
The nerves of muscle may be displayed in a thin layer of
delicate fibres which form  a part of the abdominal wall of a
frog, by employing a comlpressorium. The capillary bloodvessels may be seen when injected, in the thin recti muscles of
the eyes of small birds. By the use of the compressor, these
latter, if seen soon after death, will, without injection, show
both nerves and capillaries.
NERVE. —The dissection of nerves, to show their ultimate
structure, is similar to that of muscle, above described.  It
should be performed, however, in a little serum or white of an
egg; as water, &c., changes its appearance. As soon as the
true structure has been well seen; water, ether, &c., may be




92                THE  MICROSCOPIST.
added, to show how much they change its original appearance.
In all examinations of nerve or muscle; the more delicate the
structure, the sooner after death should it be dissected.
FIBROUS AND AREOLAR TIssuE.-Nearly allied to involuntary muscular fibre is a fibrous tissue termed the yellow or
elastic; this is often found in connexion with another, finer
and less elastic, and called from  its colour, the white fibrous
tissue; a mixture of the two is known to anatomists as the
areolar tissue, and is largely used in the animal economy,
as it forms a support for all the vessels, nerves, and muscles, from  either of which it may be easily procured.  The
yellow tissue is found in nearly an isolated condition in the
ligamentum nuchke of the necks of some animals, especially
of the ruminating tribe; it also enters largely into the formnation of the intervertebral discs.  A  portion of the ligament
from the neck of a sheep or calf, even after boiling, will exhibit the elastic fibres exceedingly well; they are of nearly
uniform  size, generally curled at their extremities, and of a
yellowish colour. They may be prepared as muscle or nerve,
with the needle points.
If any of the above tissues are to be kept they should be
mounted in fluid, as spirit and water, or the creasote liquid.
MU[cous MEMBRANE.-This is the investment of all the
internal parts of the body, continuous with the skin. Every
cavity, organ, or gland, which opens on the surface, is lined by
it.  Shut sacs are lined by serous membrane.
The mucous membrane may be divided into two parts: the
epithelium, and the basement membrane.  The external skin
is evidently a similar structure, somewhat modified, and is
capable, under certain circumstances, of taking on a similar
function.  The epithelium of skin is the cuticle or epidermis,
but the basement membrane, though present, is not easily
shown, except where the surface is raised into papillhc.




PROCURING  OBJECTS.                    93
The epithelium exists in three varieties: the scaly, prismatic, and spheroidal.  The first kind is most largely developed in the skin; the cuticle, with its horns, hairs, hoofs, and
feathers, &e., is made up of it.  Detached scales may be obtained from the inner side of the mouth, &c.  The prismatic;
or, according to Dr. Todd, the columnar; is abundant throughout
the stomach and intestines, and even the lungs.  Each prism
is attached by its sides to its fellows, and endwise to the basement membrane. The attached extremity is generally pointed,
the free one wide and fiat, and covered with vibratile cilia,
which may be often observed in rapid motion, some time after
the death of the animal.  The third variety, or spheroidal, is
to be met with in all glandular structures, as the tubes of the
stomach and kidney, and the secreting structure of the liver.
The basement membrane is structureless, and is not supplied
in any way with vessels.  The best places for viewing it are
the tubes of the kidney and stomach, and the villi of the small
intestines.  It is supported upon a submucous areolar tissue,
in which both the blood vessels and nerves ramify, but do not
in any case enter the mucous membrane.
In order to examine the surface of mucous membranes, the
mucus should be washed off as gently as possible, by a small
stream of water or a small syringe.  If the epithelium be required, it may be detached from  the surface with a scalpel,
placed on a glass slide, and viewed as a transparent object, with
a power of 200 diameters.  The mucous membrane itself may
be seen by reflected light while under water; a mlovable dissecting microscope being brought over it.  In order to obtain
a correct idea of the external surface, sections, both horizontal
and vertical, should be taken and submitted to high powers.
When the membrane cannot be well cut into thin slices, it
may be separated with the needles, or by slight pressure in
the compressorium. Where epithelium is so abundant as to




94                TIEE MICROSCOPIST.
form a layer of cuticle, it must be removed by maceration, in
order to see the mucous surface.
The arrangement of the capillaries, as seen in the injected
mucous membranes, is exceedingly interesting, and forms a numerous class of preparations.
CILIARY MOVEMENT. —If the roof of the mouth of a living
frog be scraped with the end of a scalpel, and the detached
mucous matter placed on a glass slide, and examined with a
power of 200 diameters, the epithelium cells, and the movement of their cilia, may be well seen.  The most common
method is, however, to cut off with a pair of fine scissors a
small portion of the gills (branchire) of an oyster or mussel;
lay it on a slide or on a tablet of an animalcule cage, with a
drop or two of the fluid from  the shell.  With the needlepoints separate the filaments from  each other, and cover it
lightly with a thin piece of glass.  The cilia may then be seen
in several rows, beating and lashing the water with amazing
activity.  If fresh water be added instead of that friom the
shell, the movement will speedily stop.  The motion and
structure of the cilia is sometimes better observed after the
lapse of some hours, as the movement will then have become
sluggish.
INJECTED PREPARATIONS.-We have already referred to
the arrangement of the capillaries in mucous membranes, muscular tissue, the eye, &e.  A collection of such preparations is
of considerable importance.
There can be no doubt, but that the blood is, parc excellence,
the vital fluid.  From  it is derived the material for the development of each part of the organization; nerve, as well as imuscle, bone, tendon, &c.  Even unnatural and morbid growths
must have their origin in some alteration in this all-pervading,
all-sustaining fluid.  " The life thereof is the blood thereof."
The capillary vessels of the body form  the vehicle of vital




PROCURING  OBJECTS.                      95
distribution and stimulus. By them is conveyed the nutrition
of all the tissues; and through them all foreign substances are
extractedl, and the blood thus rendered pure and vital.  By
endosmotic action through their thin coats in the lungs, oxygen unites with the carbon, and probably the iron of the blood,
and carbonic acid gas is expelled; and from their peculiar arrangement in the kidney, lobules of the liver, &c., effete matters are strained, as it were, from the circulation, and carried
off.
But there is another function, of equal, if not superior, importance with those just mentioned, which, in the judgment of
the author of this work, the capillaries are destined to subserve.
They are, doubtless, the cause, perhaps the sole cause, of the
difference in the sensations experienced in the various organs
and tissues of the animal frame, under the stimulus of the
varied excitants to which the organization is subject in health
and disease.  The nervous cords may transmit impressions to
the sensoriumn, but it is the stimulus of the blood —the vital
fluid-variously modified by the capillaries, which determines
the character of those impressions.  Hence we find that those
parts which are but slightly supplied with capillary vessels
are comparatively dull of sensation, and vice versca.  How
otherwise can we account for the different sensations produced
by inflammation in different tissues; as for instance, the burning, pungent pain of inflamed skin, contrasted with the dull,
aching sensation of inflammation in the fibrous tissue.
MIay not the peculiar and delicate arrangements of the capillaries in the different coats of the eye; the ear; the papillke
of the skin; and other organs of special sense; be referred to
the same design?
Other physiological facts also tend to establish this view.
"If the abdominal aorta be tied, the muscles of the lower
extremities will be paralysed, and on removing the ligature,




96                THE MICROSCOPIST.
and allowing the blood to flow, the muscles will recover themselves." (Todd and Bowman.)  WVe know, too, that the
stimulus of too much, or too rapid, blood on the brain, will
produce delirium, and illusions of special sense':-impressions
being made on the sensorium  independent of the action of
usual external stimuli.
The theory above referred to, in order to explain or account
for these phenomena, may be expressed as follows: —The
principle of life, or the capacity for vital action, is a property
impressed by the Great Creator upon the material organization
of both animals and vegetables. In addition to this, the properties of sensation and volition have been imparted to all animals.  These properties point out the existence of a spiritual
being or entity (distinct from vital organization), which holds
its connexion with each part of the animal frame by means of
the nervous system. It is, however, essential to the integrity
of this connexion, and to the proper performance of the functions of volition and sensation, that the nerves should be
supplied with the proper vital stimulus of the organizationthe blood-and the mode in which this stimulus is supplied,
will determine the character of the impressions made upon, or
received by, the entity or being referred to.
This entity, which some have confounded with the vital
principle, acts through the nerves in a manner peculiar to itself.
The force or material by which it holds connexion with the
bodily frame is not electricity, although in some respects its
properties are analogous.  Messrs. Todd and Bowman present
the following arguments, which prove conclusively the last
remark.  They show that the electric fluid could not be sufficiently insulated in the minute nerve-tubes to enable them to
be proper conductors-that the most delicate tests of electricity fail to discover it, when applied to nerve in action-that a
ligature to a nerve stops the propagation of nervous power, but




PROCURING  OBJECTS.                     97
not of electricity-that if a piece of nerve be cut out and be
replaced by an electric conductor, electricity will be transmitted when applied, but no nervous force excited by stimulus
above the section will pass to the parts below-and that both
nerve and muscle are infinitely worse conductors of electricity
than copper or other metals.  These facts are clearly opposed
to the present popular theory of the identity of nervous force
and electricity.
3More extended remarks upon our theory of the cause of
sensations would be out of place in a work of this kind; yet as
the varied shapes and arrangement of the capillaries must be
demonstrated by means of the microscope, and as we have
seen no theory which attempts to explain the design of such
variations, an allusion to this seemed to be appropriate.
It may be mentioned, however, that this view will throw
great light upon the cause and cure of insanity, as well as other
diseases; and upon the mocdus operandi of many articles of
the materia medica.  It is, indeed, a question worthy to be
entertained, whether diseases, which are so clearly divisible
into sthenic and asthenie, may not, after all, chiefly result
from an alteration of tone or capacity in the capillaries of an
organ, tissue, or of the whole system. Cullen's idea, that
fever is caused by a spasm in the capillaries, may not be far
from the truth, though it be but a theory.
To sum up all which our present limits will allow; the
capillaries are the most interesting and important vessels of the
body, and yet, perhaps, the least studied. A work specially
devoted to them-their description and properties-would be
a valuable accession to physiological science.
9




CHAP'TER VII.
TEST OBJECTS.
THE discovery of this class of objects by Dr. Goring, a full
account of which may be found in Mr. Pritchard's works on
the Microscope, was the chief cause of the modern improvements in the achromatic compound microscope.
Mr. Pritchard, following Dr. Goring, divides test objects
into two classes, viz., tests of the penetrating power, and tests
of the defining power of the instrument; the first showing its
destitution of spherical and chromatic aberration, and mlechanical imperfection; and the other class showing  its angle of
aperture.
This distinction is not now necessary, as few persons, save
those engaged in the manufacture of object-glasses, attend to
the former, the improvement in achromatic object-glasses having been so extensive that a good instrument, in this respect,
is readily procurable.  Still, it may be well to give an outline
of the means by which the presence or absence of achromaticity may be known.
Chromatic aberration is rendered sensible by almost any
transparent object, when the light falls upon it obliquely; but
more especially by such as are not transparent, but only illuminated by intercepted light, of which a very good example
may be seen in a piece of fine wire sieve, treated like a diaphanous object, also in a thin plate of metal perforated by very




TEST OBJECTS.                       99
small holes.  The various colours are seen according to the
order of their refrangibility, by putting the object both within
and without the focus, as well as by viewing it at the focal point.
Spherical aberration is most sensibly felt in viewing opaque
objects, especially if of the brilliant class.  It shows itself in
a variety of ways: first, as a diffused nebulosity over the whole
field of view; secondly, as a confined nebulosity, extending
only to a certain distance from the object; and thirdly, in a
want of sharpness and decision in the outline caused by a
penumbra or double image, which can never be made to lap
perfectly over the stronger or true one. Destitution of spherical aberration is evinced by the absence of these appearances,
and by the vanishing of the image immediately that the object
is put out of focus either way.
To ascertain the defects alluded to above, a minute globule
of mercury on a black ground, known as an " artificial star,"
is used.  It presents a very minute point of light.  Very minute globules of mercury, spread over a blackened surface, are
viewed as opaque objects, being illuminated by the light from
a window or lamp thrown on them by a condensing lens.
Wrhen one of these globules is in the focus of a single lens
object-glass, a strong coma surrounds the miniature image of
the window seen in the globule, and when within or without
the focus, the light of the window swells out into a circular
disc.  These appearances are more or less accompanied by
prismatic colours.
When an achromatic combination, perfectly corrected for
both kinds of aberration, is employed, the globule should exhibit similar appearances both within and without the best
focus; and when at the focus, the point of light should be seen
as a minute disc, free from  irradiations and colour, except a
general blueness, which results from the irrationality of the
spectra of the different glasses of which the object-glass is
composed.




100               THE  MICROSCOPIST.
Power of definition depends, in a great measure, upon the
angle of aperture of the object-glass.  A deficiency of angular
aperture is shown by a want of light, producing nnsatisfactory
vision, which is rather increased than ameliorated by augmenting the intensity of the artificial illumination; by an incapacity of showing lined objects, except such as are of the lowest
class; and by giving very large spurious discs with artificial
stars; also by showing easy test objects with the lines faint,
while the spaces between them  are darker and more opaque
than they ought to be.
When the aberrations are properly corrected, and the angle
of aperture considerable, the lines on test objects become fine,
sharp, and dark, and the spaces between them  bright, provided the illumination has been properly conducted; they
moreover become visible in a very faint light; the outline and
the lines are seen at once; and the spurious discs of all brilliant points are very sharp and small.
In order to explain more fully what is meant by angular
aperture, let A and a, Figs. 23 and 24, represent two objects,
in all respects alike; and suppose B, B, and b, b, to be two
object-glasses of equal focal length; the former a single lens,
of the best construction, such as was used in the old compound
microscope, and the latter a lens of the newest form, termed
an achromatic.  Now these object-glasses will form their respective images at I and i, and they will be of equal dimensions.  But if the number of rays proceeding from  A and
falling upon the single lens B, B, is not enough, when collected at I, sufficiently to stimulate the eye, any minute pore,
stria or other marking at A, will not be rendered visible;
while from  the increase of aperture in b, b, allowing much
more light to be transmitted, every mark at a will be represented at i, and the eye being powerfully acted on by the
increase of light, will be highly sensible of it.




TES T OBJECTS.                    101
The angles B, A, B, and b, a, b, are the angles of aperture
of the respective object-glasses, and the quantity of light
transmitted will be as the squares of B, B, and b, b, their focal
length being equal.
Fig. 23.                  Fig. 24.
It may be supposed, that if we throw more light upon an
object, so that more may be collected by the object-glass, we
shall be better able to define its structure; and this would
probably be the case if we could throw light only upon those
minute parts which we wish to examine, and not upon the
whole object, but as we cannot increase the relative proportions of light, the advantages proposed cannot be derived.
98




102               THIE MICROSCOPIST.
In examining test objects it will be well to remember that
there are generally some very easy ones, even among samples
of the most difficult kind. The darker the specimen, the more
easily is it made out; and the more transparent the tissue, the
greater difficulty there is in developing its structure.  Great
attention too should be paid to the proper illumination of the
object, or a superior instrument will be undervalued.
The following list affords an account of those objects most
frequently used as tests of the defining power of the instrument.
BAT'S HAIR. —This is a most beautiful structure, presenting
a series of scale-like projections arranged in the form  of a
whorl around the central part or shaft.  They are least numerous at the base of the hair, and increase towards the apex.
BMOUSE HAIR differs materially from the other in size and
structure. Their internal structure is cellular, there being
three or more rows of cells in each hair, the colour of the hair
depending on the pigment within the cells.  Under the microscope all hairs should have their light or transparent parts
clearly and distinctly separated from the darker portions, and
it is from  the sharpness with which the parts are separated
that a correct opinion of the value of an instrument can be
obtained.
In selecting hair of animals for examination, the lightest
coloured should be preferred.  Like the scales on insects, the
hair from  different parts of the same individual varies considerably in structure.
H-AIR OF THE I)ERMESTES.-This very remarkable hair is
obtained from the larva of a small beetle, which preys on dried
animal substances, as bacon and lhams.  It is covered with
brownish hairs, the longest of which are selected.
The shaft of this hair is covered with whorls of close-set
spines, and at the head is invested with a curious arrangement,
consisting of several large filaments or spines, which are




TEST  OBJECTS.                    103
pointed at their distal extremities, and provided with a protuberance at their proximal ends.
This object, with the others above noticed, is a good test of
the defining power of a half-inch object-glass.
SCALEs OF INSECTS.-The dust on the wings and bodies of
butterflies, moths, and other insects, prove, on microscopic examination, to be scales or feathers, overlapping each other like
the shingles on the roof of a house. They vary much in form
and size; and from the difficulty of developing their structure,
they form excellent test objects.  In the present list the most
easy are first named.
Lel2isma Sacchcarina.-These silvery-scaled insects frequent
closets, book-shelves, &e., and are very common.  Their scales
are very pretty objects, but are so easily made out as hardly to
deserve the name of test objects.  The longitudinal strim
appear to stand out in bold relief, like the ribs of a shell. A
good glass should show well the contrast between the stripe and
the interspaces.
_Molfopo  lfenelaus.-The pale blue scales from  the upper
surface of the wing of this splendid butterfly form  a good
test for the half-inch object-glass, which should show clearly
the transverse as well as the longitudinal strife, giving it a
brickwork appearance.  If the scale be flat, which is not common, the strive should be seen over the whole surface.  Sometimes the scales are damaged, the pigment having been removed; in such cases the cross strive cannot be seen. The pigment, under very high powers, exhibits a dotted appearance
between the strie.
Tinea Vestianelza, or Clothes Moth.-The scales of these
insects are very delicate, and require some tact in the management of the illumination to resolve their lines distinctly. The
small scales from the under side of the wing should be taken;
the others are easy.




104               THIE nMICRO SOPIST.
-outia Bracssicce, or Common (YcLbbacge Butltery.-The pale,
slender, double-headed feathers, having brush-like appendages
at their insertion, are good test objects. The specimens which
are easily resolved are short, broad, and more opaque.  The
strie are longitudinal, and with a power of 500 diameters appear to be composed of rows of little squares or beads.
Podura p~lumbea, or Lead- Colourecd Springtail.-The body
and legs of these tiny creatures are covered with scales of
great delicacy. The surface of each, under a power of 500
diameters, appears covered with numbers of delicate wedgeshaiped dots or scales, arranged so as to form both longitudinal
and transverse wavy markings.  A very small scale is a good
test of the defining power of a one-twelfth or one-sixteenthinch object-glass.  The small scales may easily be rubbed off
the scale to be examined, unless great care be taken in mounting, &c., and, of course, it will be useless as a test object.
SHELLS OF INFUSORIA.-Several delicate species serve as
test objects.  The so-called longitudinal and transverse striec
are resolved by superior instruments into dots or bead-like
projections from the surface.  The lcaviculct h]IfpCoccan2eIus, N.
angtultct, N. 8i2encervii, &c., have been recommended as tests.
A  species marked N-avicdlca atteLnuata, is a good object, requiring delicate illumination under a high power, in order to
show the longitudinal stria or dots.  Several kinds of Tripoli
may also be used for the purpose.
As it is always a tedious matter with the use of a high
power to find a minute object on the slide under the stage, it
will be most convenient to bring it first into the centre of the
field by the use of a lower power, and afterwards substitute the
high power object-glass.




CHAPTER VIII.
ON DISSECTING  OBJECTS FOR THE MICROSCOPE.
REFERENCE has already been made in Chapter V. to the
manner of dissecting and preparing certain animal and vegetable tissues, yet much has been omitted, which may perhaps
be more fully appreciated under the present head.
The instruments required in microscopic dissections; or minute anatomy; are various kinds of forceps, scissors, scalpels,
needles, troughs, loaded corks, and arm-rests.
The forceps, in addition to the ordinary forceps used in
coarse or rough dissection, may be made with closely-fitting,
sharp points. The scissors are similar to those used for surgical purposes.  It is useful to have a pair with the point of one
of its blades blunt and truncated, for cutting open tubular
parts, as the alimentary canal.  Scissors with curved blades
are also of service.  A  pair of very small scissors, whose
Fig. 25.
- ___ _ _ _ _ _ _
blades are kept open by a spring, a, Fig. 25, was much used
by Swammerdam in his dissections.  One of the handles is




106               THE  MICROSCOPIST.
attached to a piece of wood, b; the other is curved as at c, in
order to be pressed upon by the thumb or forefinger in the act
of cutting.
T''he ordinary scalpels or knives are usually too large for all
purposes; those, however, which are used in operations on the
eye will be of service.
For making fine sections, a scalpel or a razor may be employed, but for soft substances, as the liver, spleen, and kidFig. 26.
ney, a knife with two parallel blades, called Valentin's Knife,
Fig. 26, may be used with advantage.  Dissecting needles
may be straight or curved.  One of the latter, fixed in a proper handle, is represented in Fig. 27. These are very serviceable instruments for separating or tearing  asunder delicate
tissues.
Fig. 27.
As most dissections are made under water, convenient troughs
are necessary.  They may be from  two inches to a foot long
and of a proportionate breadth and depth.:IEarthenware, or
glass, is the best material.
Loadcecd corks are fiat pieces of cork covered on their under
surface with sheet lead, so that they may readily sink in the
water.  To these corks the subject to be dissected is fastened
with pins.




DISSECTING  OBJECTS.                    107
Rests are inclined planes of wood; one on each side of the
trough holding the specimen.  If the Dissecting Mieroscope
represented by Fig. 5, is used, neither rests nor troughs will
be required, other than are furnished with the instrument;
unless it be troughs for specimens not imluediately under examination.
In addition to these instruments, a small syringe, camel'shair pencil brushes, &c. &c., will be found useful.
The following account of Swammlerdam's dissections commends itself to all microscopists.  It is condensed from  an
extract in Adams's Essays, from Boerhaave's Life of Swammerdclam.
In the preparation of objects, no man was ever more successful or more indefatigable than Swammnerdam.  His chief
art seems to have been in constructing very fine scissors, and
giving them an extreme sharpness; these he made use of to
cut very minute objects, because they dissected them equally,
whereas knives and lancets, if ever so fine and sharp, are apt
to disorder delicate substances. His knives, lancets, and styles,
were so fine that he could not see to sharpen them without a
magnifying glass.
I-He was also dexterous in the management of small glass
tubes, which were no thicker than a bristle, and drawn to a
fine point at one end, but thicker at the other. These he made
use of to show and blow up the smallest vessels discoverable
by the microscope; to trace, distinguishI and separate their
courses and communications, or to inject them  with subtile
liquors.
He used to suffocate insects in spirits of wine or turpentine,
and likewise preserved them  some time in these liquids; by
which means he kept the parts from decomposition, and added
to them such strength and firmness as rendered the dissections
more easy.  When he had divided transversely the little
creature he intended to examine, and carefully noted every



108               TlHE  MICROSCOPIST.
thing that appeared without further dissection, he then proceeded to extract the viscera in a very cautious and leisurely
manner; first taking care to wash away and separate, with
fine pencils, the fat with which insects are plentifully supplied.
Sometimes he put into water the delicate viscera of the
insects he had suffocated; and then shaking them  gently, he
procured himself an opportunity of examining them, especially
the air-vessels and trachea, which by this means he could
separate fromn all the other parts.  Again, he has frequently
made punctures in other insects with a needle, and after
squeezing out all their moisture through the holes made in
this manner, he filled thlem with air, by means of slender glass
tubes, then dried them in the shade, and anointed them with oil
of spike, by which means they retained their proper forms for a
long time. He had a singular secret whereby he could preserve the nerves of insects as limber and perspicuous as ever
they had been. Some insects he injected with wax instead of
air.
Ile discovered that the fat of all insects was perfectly soluble in oil of turpentine; thus he was enabled to show the
viscera plainly, only after this operation he used to cleanse and
wash them  well and often in water.  He frequently spent
whole days in thus cleansing a single caterpillar of its fat, in
order to discover the true construction of this insect's heart.
His singular sagacity in stripping off the skin of caterpillars
that were on the point of spinning their cones dCeserves notice.
This he effected by letting them  drop by their threads into
scalding water, and suddenly withdrawing them; for by this
means the epidermis peeled off very easily; and when this was
done, he put them  into distilled vinegar and spirit of wine,
mixed together in equal proportions, which, by giving a proper
firmness to the parts, afforded an opportunity of separating




DISSECTING  OBJECTS.                    109
them, with very little trouble, from the exuvie, or skins, without any danger to the parts; so that by this contrivance the
pupa could be shown to be wrapped up in the caterpillar, and
the butterfly in the pupa.
Those who look into the works of Swammerdam, will be
abundantly gratified, whether they consider his immense labour and unremitting ardour in these pursuits, or his wonderful devotion and piety.  On one hand, his genius urged him
to examine the miracles of the Great Creator in his natural
productions; while, on the other, the love of that same Allperfect Being, rooted in his mind, struggled hard to persuade
him that God alone, and not his creatures, was worthy of his
researches, love,, and attention.
To render this section more perfect, a few further remarks
on the internal anatomy of insects will not be out of place.
2For the anatomy of other parts of the animal organization, the
reader is referred to Chapter V., and the usual text books.
1. TJacheae, or Respimratory System of Insects.-IRespiration
in insects is effected by means of two great longitudinal vessels or canals called trachem, running along the sides of the
body beneath the outer integuments and muscles, terminating
in breathing pores (spiracles or stigmata).  These pores or
spiracles are placed along each side of the body in terrestrial
insects, and are furnished with a beautiful mechanism to prevent the admission of foreign particles.  The trachem emit an
infinite number of ramifications, extending to all parts of the
body, so that air circulates freely in every part.  The trachea
consist of an elastic spiral cartilage rolled up into a tube,
lined on each side with cellular tissue. In Fig. 28 the trachea
of the larva of the Cossts ligniperda, or willow moth, is represented. Along each side of the caterpillar are seen the
spiracles.
To obtain the tracheae, &c., the insect should be placed in a
10




110               THE MICROSCOPIST.
small trough with water, and be securely fixed to a loaded cork.
The body being laid open, next to the large viscera, the tracheae will become visible.  The stomach and intestinal canal,
if large and transparent, will exhibit the minute ramifications
Fig. 28.
of the trachee the best; for this purpose, after being slit
open and well washed, they should be either mounted in fluid
or be placed on a slide to dry. If care be taken in the mounting, they will show very well in balsam.  When the entire
tracheal system is required to be dissected from the larva of
an insect, all the viscera should be taken out; the main
trunks with their tufts of branches, will then be seen running
down on either side of the body, and if care be taken in the
dissection, the whole system may be removed from the cavity,
and laid out, or rather floated on, a slide to dry, previous to
being mounted in balsam.  The spiracles require ver  little




DISSECTING  OBJECTS.                  111
dissection.  They may be cut from the body with a scalpel or
pair of scissors, and be mounted in fluid or in balsam.
2. The Digestive Systegm consists of the pharynx; the esophagus, or gullet; the craw, or crop; the gizzard, or ventriculus; the stomach, or duodenum; the intestines; and a
number of slender memlbranous tubes filled with a fluid
analogous to bile. In addition to these, the salivary glands
may be mentioned.
There is very great variety in the digestive apparatus of
insects.  In those which feed on flesh, the alimentary canal is
short, as in the higher animals, and in the vegetable eaters it
Fig. 29.
is long. There are also differences of structure, which clearly
show the adaptation of means to ends.  A, Fig. 29, is the
digestive system of J{elolontha.  B, is that of Blatta Ameri



112              TiE MlICROSCOPIST.
cana (American Cockroach), a is the esophagus, b the crop, at
the bottom of which is the gizzard, c, consisting of several
teeth arranged like a funnel, with the apices of the teeth in
the centre. Another view of the gizzard is seen at C. The
bile-tubes or liver are shown at ci, and the salivary glands at e.
Attached to the stomach, just below the gizzard, are eight
blind sacs,f, the use of which is unknown, but is supposed
to be analogous to the pancreas.
The salivary glands, stomach, &c., should be generally
mounted in fluid.  Gizzards may be put up in balsam.  The
gizzard of a cricket is an interesting object; it has over two
hundred teeth.
3. The Nervous System consists of two medullary cords or
threads, which run along the middle of the abdomen inside,
exhibiting a series of knots or ganglia.
Fig. 30 exhibits the nervous system of a caterpillar, from a
preparation of Dr. Goadby's.  The double ganglion, A, seems
to occupy the place of the cerebellum, and B, also double, and
transverse to the others, answers to the cerebrum.  C, C, the
two cords uniting them.  E, the space through which the
esophagus passes.  F, F, F, the ganglia which unite the two
cords. The distribution of the nerves through the body is
from the ganglia.  The apparent exceptions to this, as at D,
are proven, by Dr. Goadby's investigations on the Limulus, to
be, in fact, arteries, as they have been injected.  Coagulated
insect blood is white, hence they appear like nerves.
4. Th/e Circulcttory SIystem is placed along the back, and
consists of a heart or dorsal vessel; which is a tube divided
into chambers, separated from each other by valves. There are
also valves at the sides to receive the blood from the venous
sinuses of the body. But a single artery has been seen, which
goes to the head, dividing into three branches. It was thought
that the blood exuded through the vessel and found its way
through the body as it best could, back to the heart; but in




DISSECTING  OBJECTS.                     113
dissecting a Limulus (king-crab), Dr. Goadby traced the artery
into certain large sacs or vessels, evidently answering the purpose of veins (venous sinuses). It is probable the same holds
Fig. 30.                           rig. 31.!                                  XC
good of insects.  Fig. 31 represents the dorsal vessel in the
larva of Ephemera. The arrows indicate the current of the
fluid.
The muscular system of insects is very extensive.  Lyonet
dissected and described 4061 in the caterpillar of the goat moth
(Cossus ignijpi2erdcT).
10*




CHAPTER IX.
THE  CELL-DOCTRINE  OF PHYSIOLOGY.
REFERENCE has already been made at page 96 to the cause
of vitality; alluding to it as a peculiar property impressed by
the Creator on all organized structure, —a property altogether
distinct from Volition and Sensation, which exclusively belong
to animals, and which point out the existence of a special entity,
or being, resident in the organism, but whose properties cannot properly be referred either to matter or its organization.
Respecting the essential nature of the vital principle, much
speculation has been uselessly employed.  Some have confounded it with the entity, or being, in the animal, which
rerceives and wills.  But this is manifestly an error, inasmuch
as it pertains also to vegetables.  Very many parts of the
organization, also, have  an  independent vitality  (without
special sensibility), separate from that of other parts, as we
shall see in the progress of this chapter.  It seems, therefore,
most reasonable to define it as a peculiar property of organization; as gravitation, electricity, &c., are special properties of
matter under other circumstances, the essential nature of which
are just as mysterious as that of Life.
Mysterious as this subject is, it is nevertheless interesting to
trace the origin and development of organized structures; and
the progress of modern science has supplied us with the means




THE  CELL-DOCTRINE  OF PHYSIOLOGY.   115
of instruction.  Chemistry teaches us that the ultimate elements of organized bodies are identical with the elements of
other bodies; and the microscope detects the earliest forms
produced by the vital process, and the part sustained by them
in the development of each species.
Chemical analysis shows, that what are termed simple elements, as oxygen, hydrogen, carbon, nitrogen, sulphur, &c.,
are peculiarly arranged in all organized bodies; having special
affinities which they do not possess in unorganized substances,
or bodies destitute of life. These peculiar affinities form a
class of compound substances called proximate principles, or
organic compountcis or organizable substances.  They are obtained by the analysis of organized textures: such are albumen,
fibrin, starch, gluten, &c.
Owing to the feeble affinity of the simple elements in the
organic compounds, there is a great tendency in them to enter
into new  combinations, forming what are called secondary
organic coSnpouncls.  Such are ureaC uric acicd, pepsine, sugar
osf  illc, &c.
Hitherto, no one has succeeded in producing the true proximate principles by chemical synthesis, and it is doubtful if
they will ever be produced elsewhere than in the living organism.
Some of the secondary organic compounds have, however, been
formed in the laboratory of the chemist; as the production of
urea from cyanate of ammonia through the action of heat,
which has been effected by W6hler.
" The simplest and most elementary organic form with which
we are acquainted, is that of a cell, containing another within
it (nucleus), which again contains a granular body (nucleolus)."
See Fig. 32.
"This appears, from the interesting researches of Schleiden
and Schwarm, to be the primary form which organic matter takes when it passes from  the condition of a proximate




116               THE  MICROSCOPIsT.
principle to that of an organized structure." (TIodd and Botwmtan.)
There are some animal tissues, however, which seem to have
a lower grade of organization than cells, being apparently
Big. 32.
produced by the simple solidification of the plastic or organizable fluid: this fluid is, however, prepared by cells, and is set
free by their rupture.  This seems to be the case with the
delicate membrane known as the Basement or Primary3/  iembrcane, beneath the epidermis or epithelium.  According to
Dr. Carpenter, in many specimens of this membrane, no vestige of cell-structure can be seen, and it resembles that of
which the walls of the cells are. themselves constituted.  In
other cases it presents a granular appearance under the microscope, and is then supposed by -Ienle to consist of the coalesced
nuclei of cells, whose development has been arrested. Other
specimens of basement membrane, however, described by
Goodsir, present a distinctly cellular structure, the cells being
polygonal, and each having its own granular nucleus.
Cells are formed in two ways; either in a previously existing, structureless fluid called a blastemna, or within the interior
of previously existing cells. In the first method, the plastic
fluid becomes opalescent from  the deposition of a number of
nucleoli; several of these become aggregated, and form  the
nucleus, within which the nucleolus can still be seen.  This
nucleus is called the cytoblast (from xuTos, a vesicle, and /3Xa 
a germ), or cell-,germ.  From the side of this nucleus a thin
transparent membrane projects like a watch-crystal from the




THE  CELL-DOCTRINE  OF PHYSIOLOGY.   117
dial, and gradually enlarges till at last the nucleus is seen only
as a spot on its wall.  The whole is then called a nucleated
cell, or ygerinal cell. The fluid in which the granules are first
deposited is called the cytoblastevma.
In the second method of development, each granule of the
nucleus has the power of developing a cell, so that the parent
cell becomes filled with one or more generations of new cells,
which may either disappear entirely, or by the rupture of the
original cells the contents may be scattered and undergo an
independent development.
Sometimes several nucleoli are seen within one nucleus, and
several nuclei within one cell.
Each cell is an independent organ, living for itself, and by
itself, and depending upon nothing but a proper supply of nutriment and of the appropriate stimuli for the continuance of
its growth and for the performance of its functions, until its
term of life is expired.
The development of cells goes on at every period during the
life of the organism.  They are found floating in immense
numbers in the blood, chyle, and lymph; and even in diseased secretions, as pus. In the inflammatory process they
are produced in great quantities; and the malignant growths,
such as cancer and fungus hmmatodes, which infest the body,
are owing to the same agencies. In short, the nucleated cell is
the agent of most of the organic processes, both in the plant
and animal, from the dawn of their existence to their full
maturation and decline.
The forms of cells are various; some being spheroidal, others
cubical, prismatic, polygonal, or cylindrical.  They are subject
also to various transformations.  Sometimes a number of
cylindrical cells are laid end to end, and by the absorption of
the transverse partitions form a continuous tube; as in the
sap vessels of plants, muscular and nervous fibre, &c.
At other times the cells are elongated and fusiform, as in




118               THE  MICROSCOPIST.
woody fibre; or they may send forth prolongations, assuming
a stellate or irregular appearance, as in the pigment cells of
the Batrachia and Fishes, or some of the vesicles in the gray
matter of the nervous system.  Further, the original boundaries of the cells may be altogether lost, from their coalescence
with each other; or their cavities be so occupied by internal
deposits that they may be mistaken for solid fibres.
The nuclei are also subject to change of form. In some
instances we find it sending out radiating prolongations, so that
it assumes a stellate form, like that of the cells of the GeraFig. 33.
nium-petal, Fig. 33; this seems also to be the case with the
nuclei of the bone cells.  In other cases it seems to resolve
itself into a fasciculus of fibres  and this Henle conceives to be
the origin of the yellow fibrous tissue. Further, it may separate into a number of distinct fibres, each composed of a linear
aggregation of granules; in this manner, the dental tubuli
appear to be formed.  Lastly, Dr. Carpenter thinks it may
disperse itself still more completely into its component granules; by the reunion of which certain peculiar vibrating filaments (the so-called spermatozoa) may be formed.




THE CELL-DOCTRINE  OF PHYSIOLOGY.    119
" In the lowest and simplest forms of living beings," says
Dr. Carpenter, " such as we meet with among the humblest
cellular plants, we find a single cell making up the whole
fabric.  This cell grows from its germ, absorbs and assimilates
nutriment, converts a part of this into the substance of its
own cell-wall, secretes another portion into its cavity, and
produces from a third the reproductive germs that are to
continue the race; and having reached its own term of life,
and completed the preparation of these germs, it bursts and
sets them free —every one of these being capable, in its turn,
of going through the same set of operations.  In the highest
forms of vegetable life, we find but a multiplication of similar
cells; amongst which these operations are distributed, as it
were, by a division of labour; so that, by the concurrent
labours of all, a more complete and permanent effect may be
produced."
Of the development of animal tissues, Todd and Bowman
present the following interesting account, in their "' Physiological Anatomy and Physiology of M~[an."'
"t The prevailing mode, in which the development of animals
takes place, is by the formation, within the parent, of a body
containing the rudiments of the future being, as well as a store
of nutrient material sufficient to nourish the embryo for a
longer or shorter period. This body is called the ovu, or egg.
It is of that form which, in a former page (see Fig. 32, page
116), has been described and delineated as the simplest which
organization produces.  It consists of a vesicular body filled
by a fluid, and enclosing another, within which is a third, consisting of one or more minute, but clear and distinct granules.
The first, or vitelline membrane of the ovum, is the wall of a
cell; it is composed of homogeneous membrane: the second,
or the germinalt vesicle of the egg, is the nucleus of the first:
and the third, which is called by embryologists the germinal




120               THE  MICROSCOPIST.
spot, is a nucleolus to the second.  It appears, from  the researches of Wagner and Barry, that the nucleus or germinal
vesicle precedes the formation of the vitelline membrane, but
the precise relation, as to the period of its formation, of the
nucleolus or germinal spot to the nucleus, has not yet been
satisfactorily made out. The germinal vesicle and spot become
the seat of a series of changes, which give rise to the development of new cells, for the formation of the emlbryo.
" At this period the embryo consists of an aggregate of cells,
and its further growth takes place by the development of new
ones. This may be accomplished in two ways: first, by the
development of new cells within the old, through the subdivision of the nucleus into two or more segments, and the formation of a cell around each, which then becomes the nucleus of
a new cell, and may in its turn be the parent of other nuclei:
and, secondly, by the formation of a granular deposit between
the cells, in which the development of the new cells takes
place. The granules cohere to each other in separate groups
here and there, to form nuclei, and around each of these a
delicate membrane is formed, which is the cell-membrane.
"In every part of the embryo the formation of nuclei and
of cells goes on in one or both of the ways above mentioned;
and, by and by, ulterior changes take place, for the production
of the elementary parts of the tissues."
The mode of development just referred to may be illustrated
by the following cuts. Fig. 34 exhibits a section of one of
the branchial cartilages of the young tadpole.  Within the
large parent-cells, that are held together by intercellular substance, a, b, c, we observe secondary cells in various stages of
development: at d, the nucleus is single; at e, it is dividing
into two; in the adjoining cell, the division into two nuclei,
d' and e', is complete; at h, two such nuclei are enclosed within
a common cell-membrane; at i, we see three new cells (one of




tHE  CELL-DOCTRINE  OF PIHYSIOLOGY.   121
them elongated, and probably about to subdivide) within the
parent; and in each of the two groups at the top and bottom
Fig. 34.
of the figure, we have four cells, separated by partitions of intercellular substance, but having manifestly originated from
one parent cell.
Fig. 35 represents endogenous cell-growth in cells of a meliceritous tumour; a, cells presenting nuclei in various stages
of development into a new generation; b, parent-cell filled
with a new generation of young cells, which have originated
froml the granules of the nucleus.
The following arrangement of animal tissues is based upon
that adopted by Dr. Carpenter.
1i. Simple membrane; homogeneous, or nearly so, employed
alone, or in the formation of compound membranes.  Its
principal character is extension, but its ultimate structure defies the highest powers of the microscope.-Examples are seen
in the posterior layer of the cornea, capsule of the lens, sarcolemnma of muscle, &c.
11




122             TTHE MICROSCOPIST.
2. Simple fibrous tissues, including the white and yellow
fibrous tissue, and the areolar tissue, which is formed from
Fig. 35.
them.  Henl6 believes the white fibrous tissue to be formed
by cells; the yellow, by nuclei.
3. Simple cells, floating separately and freely in the fluids,
as corpuscles of the blood, lymph, and chyle.
4. Simple cells developed on the free surfaces of the body,
as epidermis and epithelium.
5. Compound membranes; composed of simple membrane,
and a layer of cells, of various forms (epithelium and epidermis); or of areolar tissue and epithelium; as mucous membrane, skin, secreting glands, serous and synovial membranes.
6. Simple isolated cells, forming solid tissues by their
aggregation; as fat cells, the vesicles of gray nervous matter,




THE  CELL-DOCTRINE  OF PHYSIOLOGY.   123
absorbent cells of the villi, and the cellular parenchyma of the
spleen. In these cases the cells are held together by the bloodvessels and areolar tissue, which pass in between them; in
cartilage, and other tissues allied to it in structure, the cells are
united by intercellular substance, either homogeneous, or of a
fibrous character.
7. Selerous or hard tissues, in which the cells have been
more or less consolidated by internal deposit, and mnore or less
completely coalesced with each other; as the hair, nails, &c.
These instances may be more properly ranked under the epidermic tissues; the result of consolidated deposit is more
characteristically seen in bones and teeth.
8. Tubular tissues; formed by the coalescence of the cavities of cells; as in the capillary blood-vessels, muscular fibre,
tubuli of nerves, &c.
In some of these, as muscle and nerve, a deposit has taken
place subsequently to the coalescence of the original cells.
To these we may add,-9. Compound tissue; formed of
areolar tissue and cartilage; as fibro-cartilage.




CHAPTER X.
EXAMIINATION  OF MORBID  STRUCTURES, ETC.
FOR the purpose of making a microscopic analysis of abnormal or other fluids, certain chemicals will be required; as
liquor potasse, ammonia, ether, and alcohol, acetic, nitric,
hydrochloric and sulphuric acids; together with a few testtubes and watch-glasses.
In the case of solids, the various kinds of scalpels, dissecting needles, and Valentin's knife, will be useful.
If the subject for examination be fluid, as blood, pus, mucus, &c., a very small quantity should be put on a clean slide,
and covered with a piece of thin glass.  A fishing-tube (page
47) will be of service for this purpose.
If there be sediment in the fluid, it should be allowed to subside, when it can be transferred by the fishing-tube to the
slide.  A  small quantity of any reagent which may be desired, may be brought in contact with one of the sides of the
thin glass cover, when it will gradually insinuate itself between
the glasses, and act slowly on what is contained there.  In
other cases, the cover may be lifted up, and the reagent
added.
In the case of blood, the fluids that require to be added are
generally ordinary water; serum; and sugar or salt, dissolved
in water; but in the case of pus and mucus, which approach




MORBID  STRUCTURES, ETC.                   125
each other so nearly in many of their characters, it becomes
of importance to have some test whereby they may be distinguished from each other. The fluid employed for this
purpose is acetic acid.  When this is added to a fluid where
pus is present, the globules swell up, and several large, transparent nuclei make their appearance; but when it is added to
a fluid where mucus is present, the globules also enlarge and
show their nuclei, but not so plainly as the pus, and the liquid,
termed liquor muci, in which the globules float, is instantly
coagulated into a semi-opaque corrugated membrane.
The presence of fatty matter is ascertained by sulphuric
ether, which readily dissolves the oily part, and leaves the
membranous cell-wall untouched.
Earthy matters require the aid of the acids for their solution; these should be added in a dilute form, so that their
solvent action may be more easily witnessed.
Solid parts, as tumours, &c., that are to be examined as
transparent objects, with high powers, require to be cut into
very thin slices, and separated, if necessary, by the needlepoints. The sections should be placed on a slide, and a little
serum, or white of egg in water, added, in order to float out
certain of the parts, and to lessen the refraction of the light
at the edges of the object.  Water will answer the purpose
for some of the hard tissues, but where nucleated or other
cells, and nervous matter, are present, its use is inadmissible.
It is necessary to state, that the examination of all morbid
structures should be made as soon as convenient after their
removal from the body, as changes of form in the softer substances speedily take place; but if some time has elapsed,
the part from which the sections are taken should be at some
distance from  the surface, in order that they may be as little
altered as possible by the action of the air.
The foregoing directions have been condensed from those of
11*




126              THE MIICROSCOPIST.
Mr. Quekett, to whose book we have already been much indebted during the progress of this work.
It was at one time " fondly hoped" (says Dr. McClellan),
"that by the aid of powerful microscopes we could be able to
detect the pre-existing germs of all organic diseases in the
general circulation, and decide not only as to the species of
affection, but also concerning the degree of constitutional contamination.  It was even thought that cancers could thus be
distinguished from  scrofula and all other more innocent diseases; while, at the same time, we could form a conclusive
opinion as to the propriety of attempting or declining a surgical operation, or of instituting any mode of local treatment
for the purpose of affording relief.  But all such attempts
have proved to be illusory, and we can gather no other practical knowledge from the use of the microscope than what is
connected with the minute anatomy of the morbid structures
after they have been elaborated."  With all deference to the
opinion of so truly a great mind as the lamented MeClellan,
we may be permitted to remark, that notwithstanding much
has been done by the labours of European and other observers,
minute pathological observation is still in its infancy; yet it
has made a deep impression upon the study of medical science.
When "the minute anatomy of the morbid structures" shall
be fully known, our knowledge of organic diseases will have
advanced to a great degree of perfection.  Dr. McClellan is
not himself insensible of the advantages to be derived from
microscopic investigations, although we think he places too
little value upon them.  He says, " Chemical analyses and
microscopic researches have lately proved that a great number
of cases (of tumours) which were once thought to be scirrhous,
or cartilaginous, or osteo-sarcomatous, are really composed of
condensed fibrine of the blood, sometimes partially altered into
albumen or gelatin."




MORBID  STRUCTURES, ETC.                   127
The microscopic appearance of a fibrous tumour is exhibited
in Fig. 36 (after Vogel).  It shows interlacing fibres, C. PriFig. 36.
mary cells with nuclei and nucleoli, A, and the same cells
elongated and becoming caudclate, B. The interlacing fibres
appear to be identical with the fibres of coagulated lymph.
Malignant growths may be divided into three classes of
disease. 1. Scrofula, and its varieties. 2. Carcinoma, or
scirrho-cancer.  3. Encephaloid disease, or medullary fungus.
1. Scrofulous growths present three forms of manifestation.
In the lymphatic ganglia and in the conglomerate glands; in
well-defined spherical tubereles, which appear first as small
points or grayish granules; and depositions which appear
during the progress of typhus fever, between the muscular
and mucous coats of the intestines, in the mesenteric glands,
in and under the mucous membrane of the trachea, and sometimes in the substance of the lungs and spleen. Fig. 37 shows
the microscopic appearance of typhous matter from the mesenteric glands.  A, an amorphous, slightly granular mass, of a




128             THE MIcROscOPIST.
brownish-white colour, with an immense number of cells deposited; B, the amorphous mass treated with acetic acid, by
which it was rendered transparent, and gradually dissolved,
Pig. 37.
o
0A 
upon which many minute cells with a sharp outline came into
view, being unaffected by the acid (Vogel).
There seems no distinction between tuberculous matter and
that of scrofula or typhus. Fig. 38 exhibits tubercles in
various stages of development.  A, B, C, tubercles from the
lungs of a young man who died of tuberculosis pulmonum.
A, B, nuclei in an amorphous cytoblastema; most of the
nuclei contain nucleoli.  At C the cytoblastema has disappeared and the cells are in contact. D, tubercular cells from
the lungs of another young man. Here the cytoblastema has
also disappeared, and the nuclei are enclosed in a cell-wall; no
nucleoli are present.




MORBID  STRUCTURES, ETC.                     129
2. Carcinoma.  In cases of true scirrhus, the matrix or
stroma is constituted either by a new development of cellular
texture, or by an induration and enlargement of the original
areolar tissue of the part. The larger and coarser fibres and
Fig. 38.
lamelloe of this tissue become converted into dense and firm
ligamentous bands, which  intersect each  other in various
directions.
Vogel, and some other writers, describe a second kind of
fibres, which occur in a reticulated form, cross-barred, or in
irregular meshes. They are distinguished from the first-mentioned whitish or ligamentous bands, by being insoluble in
acetic acid.  Fig. 39 (from Vogel, after Muiller), shows the
Fig. 39.
fibrous stroma of scirrhus, as seen in the microscope. The




130               THE  M1ICROSCOPIST.
meshes are formed by bundles of carcinoma reticulare of the
breast, as they appear after the globules have been removed.
The dense, firnm, bluish-white, or yellowish and amorphouslooking substance which fills the interstices of the stroma is
rendered transparent by acetic acid, and by ammonia and other
caustic alkalies.  This, though deposited in a fluid state, acquires its solidity by coagulation, after which it is thought
that the peculiar cancer cells, or fibres, which constitute the
malignant character of the disease, are developed.
The principal forms of cells which enter into the composition of cancerous growths are —1. The irregularly caudate or
ramifying cells; 2. Larger cells filled with nuclei; and 3.
Granular cells filled and covered with granules. Besides these
Vogel describes cells with a thick wall, exhibiting a double
contour; double cells formed by the division of one or the
fusion of two cells; and pigment cells, enclosing dark, granular
pigment.
The above are transitory or effete cells. The persistent or
fibre cells are fusiform, such as occur in the development of
areolar tissue, and of simple muscular fibre. They occur in
the firm, rarely in the soft forms of cancer, and seem destined
for the formation of the areolar tissue, and the intersecting
ligamentous bands.  In  addition to all these, there appear
numerous particles or granules of broken-down lymph and fat;
large fat granules and globules; and a viscid, gelatinous fluid.
These latter, however, may be considered adventitious and not
essential formations.
The microscopic appearance of scirrhus (220 diameters) is
exhibited in Fig. 40.  Small masses that had been pared from
a recent section of the tumnour, and moistened in water, consisted entirely of an accumulation of cells. These were very
pale, varying in size and form, being sometimes roundish, a,
sometimes oval, b, or caudate, f, or again of irregular form.




MORBID  STRUCTURES, ETC.                   131
The greater number exhibited nuclei, a, b, and in some a nucleolus was visible in the nucleus, c, h; few were devoid of
Fig. 40.
nuclei; on some fat globules were observed, g. Between
these cells were perceived nuclei with or without nucleoli, d.
(Vogel.)
3. Encephaloid disease or fungoid tumour, differs from
scirrhous cancer chiefly in the great predominance of its transitory or morbidly developed cells over the fibrous and other
elementary textures which constitute the stroma (matrix) of
the tumour.  In carcinomas, the fibrous tissue predominates
and gives solidity and firmness to the whole mass. The morbid
or cancer cells never tend to develope organized fabrics, but
always to disintegration and softening down of the tumour.
Their great predominance in encephaloid, therefore, gives the
character of brain-like softness and yielding, which is the distinguishing characteristic of this form of malignant growth.
Fig. 41 represents encephaloidl, from  the liver, under the
microscope.  It appeared wholly composed of cells, which
showed distinct nuclei and nucleoli. The cells were mostly
roundish or oval, but some were caudate.  Acetic acid rendered them full and brought the nuclei plainly in view, a.




132               THE MICROSOPI ST.
Here and there some nuclei were seen in an amorphous cytoblastema.
Fig. 41.
I
Although the cells of encephaloid belong to the class of
effete or transitory cells which also occur in cancer, yet there
is a difference in the proportions of various kinds of these cells
in the two classes of tumours. The predominating cells of this
kind in fungoid tumour are the very large parent cells, with
numerous young cells or cytoblasts in their interior. They are
often as large as - th of a line in diameter; and the caudate
cells are always irregularly caudate or ramifying.
There are seldom  any of the regular caudate or elongated
cells of small size, such as go to the formation of the cellular
and fibrous tissue, and of true cancers. The fat cells and
granules are perhaps more abundant than in scirrhus.  Fig.
42 is the microscopic appearance of encephaloid, consisting of
cells of different size and form; round, oval, and caudate, but
no one form predominating over the rest. Some are very large,
a, enclosing several minute cells with nuclei.  Isolated cells,
although in a proportionately small number, contained dark
granules, b. For further observations on microscopic patho



MORBID  STRUCTURES, ETC.                 133
logy, the reader is referred to Vogel's Pathological Anatomy,
and other similar works.
Fig. 42.
The 3Monthly Journal of Medical Science for May, 1847,
contained an account of a new instrument for the diagnosis of
tumours.  It was presented to the Medical Society of Strasbourg, by M. Kiin, Professor of Physiology in that city.
"It consists in an exploring needle, having at its extremity
a small depression with cutting edges.  On plunging this instrument into a tumour to any depth, we can extract a minute
portion of the tissue of which its various layers are composed.
In this manner a microscopic examination of the tumour can
be practised on the living subject, and its nature ascertained
before having recourse to an operation."
-With respect to the Morphology of various pathological
fluids, a great deal has been effected by microscopic investigation.  In the Microscopic Journal, vol. ii., is a series of essays
on this subject, by Dr. David Gruby, translated from  the
Latin by S. J. Goodfellow, M.D., which are worthy of careful
perusal and experimental verification. The results of Dr.
Gruby's researches may be found in a tabular form at the end
of this volume.
12




CHAPTERI XI.
ON MINUTE INJECTIONS.
MERE dissection, with the most artful management of the
scalpel, cannot make a full exhibition of the true structure
of animal bodies.  The arteries are found, after death, to be
emptied of their contents, and the blood is coagulated in the
veins, which appear much collapsecl; hence anatomists, in
order to examine the circulatory apparatus, are under the
necessity of filling these vessels by means of injection, in
order to distend them as much as possible, that their ramifications may be clearly seen.  iMore especially is this necessary
when it is desired to make an exhibition of the minute
capillaries, which are so variously arranged in the different
textures and organs of the body.  These small vessels, too,
require the aid of the microscope to show their size, form, and
arrangement.
The ordinary coarse injection, may be made by melting together 16 ounces of bees'-wax, 8 ounces of resin, and 6 fluidounces of turpentine varnish, adding such colouring matter as
may be desirable, as 3 ounces vermilion, 2 ounces King's
yellow, 10 ounces blue verditer, or 5~ ounces flake-white.
This, injected into the blood-vessels by a proper syringe,
having its pipe fastened in one of the largest of those vessels,
is abundantly sufficient to show the course of the principal
arteries and veins. The parts so injected may then be dis



ON  MINUTE  INJECTIONS.                   135
sected for this purpose, dried, and varnished, and form excellent
illustrations of anatomical lectures.
When, however, it is desired to demonstrate the capillaries,
a finer injection and more delicate manipulation is required.
Indeed, it is so difficult an art, and success is so dependent on
the combination of various circumstances, that the most experienced are often defeated in their efforts.  Yet some of the
finest injections I have ever seen were made by those who
attempted it for the first time.
For minute injection (as it is called), the most essential instrument is a proper syringe.  This should be made of brass,
of such a size that the tip of the thumb may press on the
head or handle of the piston-rod when drawn out, while the
body is supported by two of the fingers of the same hand.
Fig. 43 represents a syringe, with which I have succeeded
in making some excellent *preparations.  A is the cylindrical
brass body, on the top of which screws the cap, B, a leather
washer being interposed to render it more air-tight.  C is the
piston, which is of brass, covered with wash-leather. The
bottom of the syringe, ID, also unscrews, for convenience of
cleaning.  E is a stop-cock, on the end of which another stopcock, F, fits closely.  On the end of this, one of the injectionpipes, G, which are of different sizes, may be placed.  The
transverse wires, across the injection-pipes, are designed for
the better security of the pipe in the vessel into which it is
fixed; the thread being tied behind them so that it cannot slip
forwards. A. half-dozen pipes, at least, are necessary to accompany each instrument.
In addition to the syringe, a large tin vessel to contain hot
water, with two or three lesser ones fixed in it for the injections, will be found useful.
To prepare the material for injecting:-Take of the finest




136                TIHE  MICROSCOPIST.
and most transparent glue, one pound; break it into small
pieces, put it into an earthen pot, and pour on it three pints
of cold water; let it stand twenty-four hours, stirring it now
Fig. 43.
-A
and then with a stick; then set it over a slow fire for half an
hour, or until all the pieces are perfectly dissolved; skim off




ON  MINUTE  INJECTIONS.                  137
the froth from  the surface, and strain through a flannel for
use. Isinglass, and cuttings of parchment make an excellent
size, and are preferable for very particular injections.
The size thus prepared may be coloured with any of the
following:
Red.-To P1pint of size, 2 ounces of Chinese vermilion.
Yellow.-Size, 1 pint,-chrome yellow, 2~ ounces.
White.-Size, 1 pint,-flake-white, 31 ounces.
Blue. —Size, 1 pint,-fine blue smalts, 6 ounces.
It is necessary to remember that whatever colouring matter
is employed, must be very finely levigated before it is mixed
with the injection.  This is a matter of great importance, for
a small lump or mass of colour, dirt, &c., will clog the minute
vessels, so that the injection will not pass into them, and the
object will be defeated.
The mixture of size and colour should be frequently stirred,
or the colouring matter will sink to the bottom.
Respecting the choice of a proper subject for injecting, it
may be remarked, that the injection will usually go farthest
in young subjects; and the more the creature's fluids have
been exhausted in life, the greater will be the success of the
injection.
To prepare the subject, the principal points to be aimed at
are, to dissolve the fluids, empty the vessels of them, relax the
solids, and prevent the injection from  coagulating too soon.
For this purpose it is necessary to place the animal, or part to
be injected, in warm water, as hot as the operator's hand will
bear.  This should be kept at nearly the same temperature for
some time by occasionally adding hot water. The length of
time required is in proportion to the size of the part, and the
amount of its rigidity.  Ruysch (from whom the art of injecting has been called the Ruyschian art,) recommends a previous
maceration for a day or two in cold water.
12*




138                THE  MICROSCOPIST.
When the size and the subject have both been properly prepared, have the injection as hot as the finger can well bear.
One of the pipes, G, Fig. 43, must then be placed in the
largest artery of the part, and securely tied.  Put the stopcock), F, into the open end of the pipe, and it is then ready to
receive the injection from successive applications of the syringe,
A. The injection should be thrown in by a very steady and
gentle pressure on the end of the piston-rod.  The resistance
of the vessels, when nearly full, is often considerable, but it
must not be overcome by violent pressure with the syringe.
When as much injection is passed as may be thought advisable, the preparation may be left (with the stop-cock closed in
the pipe) for twenty-four hours, when more material may be
thrown in.
As the method of injecting the minute capillaries with
coloured size is often attended with doubtful success, various
other plans have been proposed. Ruysch's method, according
to Rigerius, was to employ melted tallow, coloured with vermilion, to which, in the summer, a little white wax was
added.
Mr. Rauby's material, as published by Dr. Hales, was resin
and tallow, of each two ounces, melted and strained through
linen; to which was added three ounces of vermilion, or finely
ground indigo, which was first well rubbed with eight ounces
of turpentine varnish.
Dr. Monro recommended coloured oil of turpentine for the
small vessels, after the use of which he threw in the common
coarse injection.
Professor Breschet frequently employed with success milk,
isinglass, the alcoholic solution of gum-lac, spirit varnish, and
spirit of turpentine; but he highly commends the colouring
matter extracted  from  campeachy, fernambone, or sandal
woods. He says, " The colouring matter of campeachy wood




ON  MINUTE  INJECTIONS.                 139
easily dissolves in water and in alcohol; it is so penetrating
that it becomes rapidly spread through the vascular networks.
The sole inconvenience of this kind of injection is, that it cannot be made to distend any except most delicate vessels, and that
its ready penetration does not admit of distinguishing between
arteries, veins, and lymphatics."  He also recommends a solution of caoutchouc.
Another process, which may be termed the chemical process, was published in the Coomptes Rendus, 1841, as the
invention of M. Doyere.  According to this, an aqueous solution of bichromate of potass is propelled into the vessels; and
after a short time, in the same manner and into the same vessels an aqueous solution of acetate of lead is injected.  This is
an excellent method, as the material is quite fluid, and the
precipitation of the chromate of lead, which takes place in
the vessels themselves, gives a fine sulphur-yellow colour.
Dr. Goadby has improved upon the process last named by
uniting to the chemical solutions a portion of gelatine. The
following is his formula, originally published in the London
Lancet, and again in the Medical Examiner, March, 1850.
Saturated solution of bichromate of potash, 8 fluid ounces;
water, 8 ounces; gelatine, 2 ounces.
Saturated solution of acetate of lead, 8 fluid ounces; water,
8 ounces; gelatine, 2 ounces.
Dr. G. gives the following remarks respecting this process:
— " The majority of preparations, thus injected, require to be
dried, and mounted in Canada balsam.  Each preparation,
when placed on a slip of glass, will necessarily possess more
or less of the coloured infiltrated gelatine, (by which, he
alludes to the gelatine, coloured by the blood, which, together
with the acetate of potash resulting from the chemical decomposition, may have transuded through the coats of the vessel,)
which, when dry, forms, together with the different shades of




140              THE MICROSCOPIST.
the chromate of lead, beautiful objects, possessing depth and
richness of colour.  The gelatine also separates and defines
the different layers of vessels. By this injection the arteries
are always readily distinguishable by the purity and brightness
of the chromate of lead within them, while the veins are detected by the altered colour imparted by the blood.
"Those preparations which require to be kept wet, can be
preserved perfectly in my B  fluid-specific gravity 1'100;
the A fluid destroys them.
" I would recommend, that the slips of glass employed for
the dry preparation be instantly inscribed with the name of
the preparation, written with a diamond, for, when dry, it is
very difficult to recognise one preparation from another, until
the operator's eye be educated to the effects of this chemicogelatinous injection.  Where so much wet abounds gummed
paper is apt to come off.
"When dry, it is sufficient for the purpose of brief examination by the microscope, to wet the surface of a preparation
with clean oil of turpentine; immediately after examination,
it should be put away carefully in a box, to keep it from the
dust, until it can be mounted in Canada balsam.
" The bichromate of potash is greatly superior in colour to
the chromate, which yields too pale a yellow; and subsequent
experience has convinced me that the acetate of potash frequently effects its liberation by destruction of the capillaries,
and this, even long after the preparations have been mounted
in Canada balsam; perhaps this may be owing to some chemical
action of the acetate of potash upon them.
" I would suggest the substitution of the nitrate for the
acetate of lead, as we should then have, in the liberated
nitrate of potash, a valuable auxiliary in the process of preservation.
"Although highly desirable, as the demonstrator of the




ON  MINUTE  INJECTIONS.                   141
capillaries of normnal tissues, I do not think this kind of injection fitted for morbid preparations, the infiltrated gelatine
producing appearances of a puzzling kind, and calculated to mislead the pathologist.
" In preparing portions of dried, well-injected skin, for examination by the microscope, I have tried the effect of dilute
nitric acid, as a corroder, with very good results. But, probably, liquor potasspe would have answered this purpose better.
I" When size injection is to be employed, coloured either with
vermilion or the chromate of lead, the animal should be previously prepared by bleeding, to empty the vessels: for if
they be filled with coagulated blood, it is quite impossible to
transmit even size, to say nothing of the colouring matter.
Hence the difficulty of procuring good injections of the human
subject.
I"But with the Ichemico-gelatinous' injections no such preparation is necessary; and success should always be certain, for
the potash liquefies the blood, while constant and long-continued pressure by the syringe drives it through the parietes of
the vessel into the cellular tissue. The large quantity of infiltrated blood-the invariable, concomitant of my process —
characterizes this from all other modes of injecting, and is a
distinctive feature of these preparations."
Still another plan has been suggested (as I am informed)
by Dr. Goddard of Philadelphia.  It consists in  adding a
quantity of sulphuric ether to the finely levigated colouring
matter, which is also first ground or mixed with linseed oil, in
the manner employed by painters. Upon this plan (as well as
upon the last named) I have succeeded in making some beautiful injections of the smallest capillaries, yet I have sometimes failed, owing to the too rapid evaporation of the ether,
and the clogging up of the vessels from the early deposition of
the solid colouring matter. Perhaps a solution of gum mas



142               THE  MICROSCOPIST.
tich, &c., in ether, coloured with fine vermilion, &c., will answer
the indications better.
A fcetus may be'injected by the umbilical vein; a uterus,
by the hypogastric arteries; the head, by the carotids; the
liver, mucous membrane of the intestines, &c., by the portal
vein; an extremity, by the principal artery; &c.
Many parts, after injection, require to be macerated in water,
or corroded by dilute muriatic acid, &c., in order to exhibit the
ramifications of the small vessels. They should be very carefully handlecl, or moved, in the macerating liquor, as the slightest force may break the vessels.  When corroded, the pulpy
flesh is to be carefully washed away by placing it under a
stream of water, flowing very slowly; or by the use of a syringe
with water.
The lymphatics are usually injected with quicksilver, but
M. Rusconi and Professor Breschet, have abandoned this method for the coloured material, on account of the mercury frequently rupturing by its weight the thin, lymphatic vessels
and reservoirs.  The first-named gentleman, in his researches
on the lymphatics of reptiles, employs in place of the usual
injecting tube of Walter (used with the mercury), a small
silver syringe, together with a kind of trocar, of which the
canula is formed from the quill of the wing-feather of the quail
or partridge, the trocar being a tolerably large-sized needle,
the point of which has three facets.  When desirous of injecting the lymphatic system of a lizard, tortoise, &c., he remarks:-I I seize with a small pair of forceps the mesentery,
close to the vertebral column, where the reservoir of the chyle
is situated, and I introduce into it the point of the trocar; I
then retain the quill and withdraw the needle from the tube.
This done, I seize with the small forceps the quill, and introduce into it the small extremity of the syringe, and push the
piston with a force always decreasing."  He recommends
coloured wax, mixed with nut-oil, for the injection.




CHAPTER X I.
EXAMINATION  OF URINARY  DEPOSITS.
THE chemical composition of the urine and urinary deposits
has within a few years past attracted much attention, and has
contributed much to our knowledge respecting the nature of
diseases and their diagnosis. To examine these, the microscope
is often an essential instrument.
Deposits of uric acidc and its combinations (called red, or
yellow-sand sediments), occur in fever; in acute inflammation;
in rheumatism; in phthisis; in all the grades of dyspepsia;
in all or most stages of diseases attended with arrest of perspiration; in diseases of the genital apparatus; from  blows
and strains of the loins; from excessive indulgence in animal
food; or from too little exercise.
The deposition of earthy phosphates (white deposit), should
be regarded as of serious importance, always indicating the
existence of important functional, and frequently of organic
disorder.  According to Dr. Bird, they always exist simultaneously with a depressed state of nervous energy, often
general, rarely more local, in its seat.
Deposits of oxalate of lime are regarded by Dr. G. Bird as
by no means so rare as is generally supposed.  He believes
that it owes its origin to sugar, and is caused by derangement
of the digestive organs.
The urine may contain all or any of the elements of the




144               THE MICRPOSCOPIST.
blood.  The serum  may be effused alone, or be accompanied
with the red globules.
Whenever the elements of blood appear in the urine, there
is ample proof of the existence of active or passive hemorrhage
of the kidneys, or urinary tract.
Albumninous urine occurs in Bright's disease, dropsy after
scarlatina, &c.
Pats is met with in the urine as the result of suppuration of
the kidney, or of some part of the genito-urinary mucous membrane, or of abscesses of the neighbouring viscera, opening
into the urinary passage.
The presence of sugar is not uncommon in dyspepsia, and
when excessive is diagnostic of diabetes mellitus.
Kiesteim is a whitish, greasy, opalescent pellicle, sometimes
found on the urine of pregnant women.
To examine urinary deposits with the microscope, allow the
urine to stand; decant the supernatant fluid; pour the remainder into a watch-glass; draw off the small quantity of
fluid remaining after a short repose, by means of a pipette;
and then place it on the stage of the microscope. When, however, it is necessary to use high powers, a drop of the sediment
should be placed on a glass slide and covered with thin glass.
If it is desired to mount the object for future examination,
it can be covered, when dry, with a drop of Canada balsam,
and surmounted with the thin glass. Very transparent objects
should be kept in fluid, as weak spirit, water saturated with
creasote, or Goadby's fluid.
HEALTHY URINE holds in solution a variety of substances,
both organic and inorganic.  Chemists have not yet succeeded
in insulating all its ingredients for examination, but the most
important of its solid materials are urea, uric acid, hippuric
acid, vesical mucus and epithelial debris, animal extractive,
ammoniacal salts, fixed alkaline salts, and earthy salts.




EXAMINATION  OF URINARY  DEPOSITS.  145
The amount passed by an individual during each twenty-four
hours, varies from twenty to fifty ounces, holding in solution
from  six hundred to seven hundred grains of solid matter.
When kept for some time it gradually becomes turbid, and deposits a sediment of earthy phosphates, previously held in
solution by the slight excess of acid present. If kept still
longer, it gradually putrefies, and, becoming concentrated by
evaporation, deposits small crystals of chloride of sodium,
phosphates, and other salts, and eventually becomes covered
with a grayish-coloured mould.
iUr-ea appears to be the vehicle by which nearly the whole of
the nitrogen of the exhausted tissues of the body is removed
from the system. The proportion of urea in healthy urine
averages fourteen or fifteen parts in the one thousand. Pure
urea may be obtained by first converting it into the oxalate,
which is done by adding a strong solution of oxalic acid in hot
water, to urine previously concentrated to about one-eighth its
bulk, and filtered to free it from the insoluble sediments of
phosphates and urates.  The crystals of oxalate of urea thus
obtained, a, Fig. 44, should be dissolved in hot water, and the
solution treated with pulverized chalk as long as effervescence
is produced.  The urea remains in solution, and may be purified by boiling with animal charcoal, after which it may be
crystallized, in four-sided prisms, by careful evaporation.
Nitrate of urea may be obtained in crystals, b, Fig. 44, by
concentrating urine to about one-half its bulk, and adding an
equal quantity of nitric acid. If urea be suspected in excess,
a drop of the urine, without concentration, may be treated with
nitric acid under the microscope.
The proportion of uric acid in the healthy secretion varies
from 0'3 to 1P0 in 1000 parts.  Its forms will be represented
when we treat of the examination of urinary deposits. It may
be obtained from urine concentrated to half its bulk, by adding
13




146               THE  MICROSCOPIST.
a few drops of hydrochloric acid, and allowing it to stand a
few hours in a cool place.
Fig. 44.
Hippuric Acid is generally present in a small quantity in
healthy urine, and in certain forms of disease, especially where
a vegetable diet has been adopted.  Fig. 45 represents some
Fig. 45.
of its forms; aC are deposited from an alcoholic solution, and
b from a hot aqueous solution.
When an excess is suspected in urine, it should be evaporated to the consistence of syrup and mixed with half its bulk
of strong hydrochloric acid. After a few hours the crystals




EXAMINATION  OF URINARY  DEPOSITS.   147
may be examined with the microscope, when the tufts will
probably be seen, coloured pink by the admixture of purpurine.  If it be present only in small quantity, a few detached
needle-like or branched crystals may be seen.  It is readily
soluble in alcohol and hot water, but not in cold water.
Tesical Mucus and Epithelial Scales, which may be present,
are derived from the internal surface of the bladder and urinary passages. The quantity is so small in healthy urine as to
be scarcely visible, until, after standing, it has subsided to the
bottom of the liquid in the form of a thin cloud.
Extractive Mlgatter, includes all the uncrystallizable organic
matter found in the residue of evaporated urine, which is
soluble in water or alcohol.  When in excess, the urine appears more highly coloured than usual, a large proportion of
what is termed extractive, consisting of colouring matter, as
purpurine, &c.
Atnmoniacal Salts appear to consist chiefly of the muriate
and the urate, the latter salt being the form in which the uric
acid present in the urine appears to be held in solution.
The proportion of ammonia in healthy urine is quite small,
but in some diseases, especially in certain kinds of fever, it
increases considerably.
Fixed Alkaline Salts may be obtained by incinerating the
evaporated residue of urine, when a white ash will be left,
consisting of a mixture of alkaline and earthy salts; the former may be separated from the latter by dissolving in water,
in which the earthy salts are insoluble.
The alkaline salts, which in the healthy secretion usually
amount to thirteen or fourteen parts in one thousand, consist
of the sulphates of potash and soda, chloride of sodium, chloride of potassium, and phosphate of soda.  The crystallized
residue, after slowly evaporating a few drops on a piece of glass,
usually has the appearance represented in Fig. 46. The cross



148              THE MICROSCOPIST.
lets consist of chloride of sodium; the more plumose crystals
are probably phosphate of soda.
Fig. 46,
a              ~''o           O- d v
C+loot
VThe Ea#rthy -Salts which form  the insoluble portion of the
ash, and which usually amount in healthy urine to about 1
part in 1000, consist of the phosphates of lime and magnesia,
together with a small trace of silica.  These appear to be retained in solution in the urine by the small excess of acid
(probably phosphoric) usually present, and may be precipitated
from it by supersaturating with ammonia. The precipitate
thus formed consists of a mixture of phosphate of lime, and
the double phosphate of ammonia and magnesia, which is
also called triple phosphate. These, with the abnormal ingredients found in morbid urine, &e., will be treated of when we
come to the examination of urinary deposits.  It must be
borne in mind, however, that a spontaneous precipitate of
earthy phosphates is not of itself a proof that they are present
in excess, for when the urine is acid, as in health, a considerable quantity may be retained in solution, while if it be neutral
or alkaline, a comparatively small proportion may be precipitated.
When urinary deposit is examined with the microscope, it




EXAMINATION OF URIN ARY DEPOSITS. 149
will be found either crystalline, antorphous, or organized.
When, as is frequently the case, the deposit consists of a
mixture of different forms, each of them in succession should
be examined, until the nature of the whole deposit is clearly
understood.
CRYSTALLINE DEPOSITS, will probably be either uric acid,
phosphate of lime and magnesia (from which the triple phosphate is formed), oxalate of lime, or perhaps cystine.
Triple Pklos2hate.-This salt (called also the double phosphate of ammonia and magnesia) is formed by supersaturating
with ammonia. Phosphate of lime is also precipitated by the
same means, but may be distinguished by the microscope.
The crystals of the triple phosphate are stellate or triangular
prisms, as seen in Fig. 47.  They disappear on the addition of
acetic acid.
Uric (or Lithic) Acicl.-This salt, like the earthy phosphates, exists in a small quantity in healthy urine, but as the
proportion varies considerably in many forms of disease, its
determination when in abnormal quantity, affords much assistance in diagnosis.
It is insoluble in alcohol, and nearly so in dilute hydrochloric and sulphuric acid; but it combines with the alkalies,
forming salts, which are insoluble or very sparingly soluble in
water.
The action of nitric acid upon uric acid is characteristic. It
will gradually dissolve it, carbonic acid and nitrogen being
given off with effervescence, leaving behind a mixture of
alloxan (CQ NM IH 01,,), alloxantine (C4 H a N  0,3), and other
compounds. This may be evaporated nearly to dryness, when
a red residue will be left, which, when cold, should be moistened with ammonia, which will develope a beautiful purple
colour, owing to the formation of murexide (C,, N, H1  08)*
13*




150               THE  MICROSCOPIST.
The crystalline forms of uric acid are various, but appear to
be modifications of the rhombic prism.
Fig. 47.
Fig. 48 represents some of its forms.
Oxalate of Limne often exists in the form of minute octahedral crystals, varying from Bath to 5-61th  of an inch in
diameter, ac Fig. 49.  When allowed to dry on the glass, each




EXAMINATION  OF URINARY  DEPOSITS.  151
crystal appears under the microscope like a black cube, having
Fig. 48.
alt       o0
in the centre a small white square opening, as shown at b.




152                THE  MICRO SCO PIST.
This is owing to the rays of light being mostly refracted beyond the field of vision. On again moistening them, the crystals reappear in their octahedral form.  Sometimes this salt
Fig. 49.
o a
assumes the forms represented at c, more or less resembling
dumb-bells.*  This form, like the crystals of uric acid, the
* Dr. Fricke, in the American Journal of Medical Science, July,
1850, states as his opinion that the dumb-bell forms of crystals are
not oxalate of lime, but disintegrated crystals of uric acid.




EXAMINATION OF URINARY DEPOSITS. 153
triple phosphate, &c., is beautifully coloured when examined
by polarized light; the octahedral variety has little or no effect
upon it, being invisible, or nearly so, when the field is dark.
If the " dumb-bells" are kept in liquid for any length of time,
they gradually pass into octahedra.
As the crystals of oxalate of lime are very transparent, and
about the same specific gravity as the urine, they may readily
escape detection, unless some considerable time is allowed for
deposition, or the urine is passed through a filter.
Oxalate of lime is insoluble in water, in acetic and oxalic
acids, and in solution of potash; but it is readily soluble in
dilute nitric and hydrochloric acids.
Cystine has occasionally been found as a crystalline deposit
and in the form of small calculi.  It may be distinguished by
being insoluble, or nearly so, in water and dilute acids, but
soluble in ammonia, from which small hexagonal crystals are
deposited on evaporation. The usual microscopic appearance
is represented at a, Fig. 50.  At b is the form left from the
amimoniacal solution.
Fig.50.
o c) 0,                        J
AMORPHOUS DEPOSITS consist probably of phosphate of
lime, urate of ammonia, urate of soda, fat, or chylous matter.
Phosphate of Limne.-This salt has already been described
as existing in urine in conjunction with the phosphate of magnesia.  It is thrown down, together with the triple phosphate




154              THIE  MICROSCOPIST.
(before noticed), on the addition of ammonia. The crystalline
shape of the triple phosphate, however, readily distinguishes
it under the microscope from the amorphous particles of phosphate of lime with which it is usually mixed. The earthy
phosphates are readily soluble in dilute acids, from which they
are precipitated by ammonia. They are insoluble in a solution
of potash.
C:rate of Amm}onia constitutes one of the most common
urinary deposits. It is gradually deposited as the urine cools,
in the form of an amorphous precipitate, which, with a high
magnifying power, appears to consist of minute rounded particles, occasionally adhering together, frequently mixed with
small crystals of uric acid, and occasionally with the earthy
phosphates.  A deposit of urate of ammonia readily dissolves
when the urine containing it is gently warmed, and is precipitated again when the liquid cools.  (The earthy phosphates
and uric acid are nearly as insoluble in hot as cold water.)
When urate of ammonia is treated with dilute acetic or
hydrochloric acid, it is decomposed, and uric acid is formed.
Urate of Soda is often met with in the urine of patients
taking medicinally the carbonate or other salts of soda. It resembles the urate of ammonia in being soluble in hot water,
and in most of its chemical characters, but may be generally
recognised without difficulty under the microscope, forming
minute globular or granular aggregations, with, occasionally,
irregular and curved protuberances.
Fat may be recognised by the particles being minute round
globules, with dark and well-defined outlines, which dissolve
when agitated with ether.
Sometimes this substance is mixed with albuminous matter,
forming a kind of emulsion, so that no trace of fat can be
perceived with the microscope. In such cases, the urine may
be agitated with a little ether, which will dissolve the fat, and




EXAMINATION  OF URINARY  DEPOSITS.  155
the solution so formed will separate from the watery liquid,
and form a distinct stratum on the surface.
Chylous actter may be known by the urine being opaque
and milky in appearance, yielding fatty matter when agitated
with ether, and containing minute, amorphous, albuminous
particles, and perhaps also colourless globules, which may
possibly be mistaken for oil globules, from which their insolubility in ether distinguishes them.
ORGANIZED DEPOSITS may either be mucus, usually mixed
with epithelium; pus; blood; or semen.
_Gitcus.-If the particles observed with the microscope are
round, or nearly so, and granulated on the surface, entangled
in tenacious, stringy masses, which do not break up and mix
uniformly with the liquid on agitation, it is probably mucus.
Epithelial debris may be recognised by the peculiar form of
its particles.  Mucous urine generally contains a considerable
amount of earthy phosphates and other matters.
Pus may be known by the particles not being held together
by any tenacious matter, but floating freely in the liquid. The
granules of pus and mucus present almost the same appearance under the microscope, although the latter may probably
be rather smaller and less distinctly granular.  Acetic acid
renders the interior nuclei visible in both, but it coagulates
the fluid portion of the mucus.
Even this test may be uncertain, on account of the dilution
of the mucous fluid, and also because the coagulation may
have been already occasioned by the presence of the large
quantity of water.  When the quantity of mucus is abundant,
however, this test will be sufficient.
Blood.-When this is suspected in the urine, it may be
examined under the microscope for any blood corpuscles that
may be in it.  If the blood has coagulated, they will probably be entangled in the coagula, and may be forced out by




156              THE  MICROSCOPIST.
gentle pressure under a strip of thin glass. If there is no
coagula, the liquid may rest for a short time, and a drop from
the bottom  examined.  The urine may also be tested for
albumen after separating the solid matter by filtering.  When
the colouring matter of the blood is present, it will coagulate
with the albumen, giving it a red or brown colour. When the
fibrin, in its soluble form, is present, it usually coagulates
spontaneously on cooling, causing the urine to become gelatinous. The coagulum of fibrin, when pressed between glasses,
is generally composed of minute amorphous particles, with a
few red blood corpuscles, quite different from the granular
mucus corpuscles, for which it might be mistaken without
microscopic examination.
Bile or purpurine in urine has nearly the same colour as
when blood is present; hence, unless the blood corpuscles are
present, we should apply the tests for the detection of those
substances before finally deciding. Purpurine will be dissolved
by treating with warm alcohol, or may be precipitated by adding a little warm aqueous solution of urate of amlmonia, which
on cooling will fall down, carrying with it the colouring matter. Bile may be tested by pouring a few drops of urine on a
white plate, and adding carefully a drop or two of nitric acid.
When bile is present in any considerable quantity, the liquid
becomes successively pale-green, violet, pink, and yellow, the
colour rapidly changing as the acid mixes with the urine.
When only slight traces of bile are present, the urine should
be concentrated by evaporation.
When semen is present in urine, it may easily be detected
under the microscope, by the appearance of minute animalcules, always found in the spermatic fluid, and hence called spermatozoa.  They are oval in shape, with long and delicate tails.
Traces of albumen may generally be detected in urine containing semen.




EXAMINATION  OF URINARY  DEPOSITS.  157
DIABETIC  AND ALBUMINOUS UrINE. —AlbumTen may be
tested by boiling the suspected urine gently in a test-tube,
when it will be coagulated.  As, however, a white precipitate
results on boiling, from an excess of earthy phosphates, it will
be necessary to add a few drops of nitric acid, which will redissolve the phosphates but leave the coagulated albumen unaffected.  Nitric acid also will coagulate albumen.  If both
heat and nitric acid throw down a white precipitate from urine
in separate portions, there can be no doubt of the presence of
albumen.
The peculiar casts of urinary tubes found in the urine of
patients suffering from Bright's disease, consist of fibrinous or
albuminous matter and entangling blood-corpuscles, epithelium,
and fatty globules.
Diabetic Sugar has the same chemical composition as that
contained in most kinds of fruit, known as grape sugar.  Several tests have been proposed for its detection in urine.
Troqmnere's Test is founded on the circumstance that when a
solution of diabetic or grape sugar is boiled with a mixture of
potash and sulphate of copper, the oxide of copper contained
in the latter is reduced to the state of suboxide, which is precipitated in the form  of a reddish-brown or ochre-coloured
granular powder.
/lMoore's Test is made by mixing a little suspected urine with
half its volume of liquor potasso and boiling gently for about
five minutes.  If sugar is present, the liquid assumes a brown
or bistre tint.
Thfe Fermenztationl Test is made by filling a test-tube with
the suspected urine, to which a little yeast has been added.
The tube is then inverted over a saucer containing some of the
urine, and set aside in a warm  place for about twenty-four
hours.  If sugar is present it undergoes the vinous fermentation by which it becomes converted into alcohol and carbonic
14




158              TIHE MICROSCOPIST.
acid. The latter rises in the tube and displaces the liquid. If
no sugar be present, no fermentation will take place, and no
gas will be formed in the tube.
Test fr'om the Growth of the Torula. — During the process of
the vinous fermentation of a liquid containing sugar, a delicate
white scum collects on the surface, which when examined with
a magnifying power of four or five hundred diameters, will be
found to consist of small, oval vesicles, a, Fig. 51, which, in
Fig. 51.
b
the course of a few hours, rapidly change their form, becoming
longer and more tubular, and give rise to new vesicles, which
shoot out from the parent body, forming an irregular jointed
confervoid stem, b.  These again break up into a great number of oval vesicles, which separate, and fall to the bottom,
where they may be detected by the microscope.
The following tables for facilitating the examination of
urine and urinary deposits, are modified from Bowman's Medical Chemistry.  The reader may also consult the Manuals of
Drs. Golding Bird, Griffith, Markwick, and Rees. The works of
the latter three gentlemen have been published in Philadelphia,
in one convenient volume.  The " Analysis" of Dr. Rees contains also a valuable essay on the treatment of urinary diseases.




EXAMINATION  OF URINARY  DEPOSITS.  159
TABLE I.
FOR TIIE CHEMICAL EXAMINATION  OF URINARY
DEPOSIT S.
1. The sediment dissolves when warmed.  Uriate of Amnonica.
2. Not soluble when warmed, but soluble in acetic acid.
Earthy PhospIhates.
3. Insoluble in acetic, but soluble in dilute hydrochloric
acid.  Oxalate of Limne.
4. Insoluble in dilute hydrochloric acid. Purple with nitric
acid and ammonia.  5ric Acid.
If neither of these, it may be,
5. Greenish-yellow  deposit, easily diffused on agitation.
Pus?
6. Ropy and tenacious.  Mucus?
7. Red or brown; not soluble when warmed; the fluid portion coagulable by heat and nitric acid.  Blood?
8. Soluble in ammonia; the solution leaving, on evaporation,
hexagonal crystals.  (ystine?
9. Yellowish sediment, soluble when warmed.  UM'ate of
Soda?
10. Ether yields, after agitation, an oily or fatty residue.
lattty Maltter.
11. 3Milky appearance.  Chylous Matter.
TABLE II.
FOR THE EXAMIINATION OF TIIE CLEAR LIQUID
PORTION.
1. Crystals with nitric acid. Excess of Ui'ea.
2. Fermentation, or Trommer's test.  Sugar.




160              Tie MICROS COPIST.
3. Precipitate formed on boiling; soluble in nitric acid.
Excess of E arthy Phos27Wctes.
4. Precipitate formed on boiling; insoluble in nitric acid.
Albzumen.
5. Precipitate formed by nitric acid.  Excess of Uric Acid,
or Albumen.
6. Concentrated urine yields needle-shaped crystals with
hydrochloric acid. HItppuric Acid.
If the urine is highly coloured,
7. Dark coagulumn formed on boiling.  Blood?
8. Red colour with hydrochloric acid.  Excess of Colourging
Matter.
9. Pink precipitate with warm solution of urate of ammonia.
Purpumrine.
10. Change of colour with nitric acid. Biliary Matter.
TABLE III.
FOR MICROSCOPIC  EXAMINATION  OF DEPOSIT.
If (Jrystallineo
1. Lozenge-shaped, &c.  Uric Acid.
2. StellT, or three-sided prisms (after saturating with ammonia).  Triple Phospchate.
3. Octahedra, or dumb-bells.  Oxalate of Lime.
4. Rosette-like tables.  Cystine.
If Amoli2rhous.
5. Soluble when warnmed.  Urate of A2nmonia.
6. Soluble in acetic acid.  Phospwhate of Lime.
7. Yellowish grains.  Urate of sSoda?




EXAMINATION  OF URINARY  DEPOSITS.   161
8. Round globules with dark edges. _Fatty Matter.
9. White and milky.  Cktylous Matter?
If Oqganizecd.
10. Granulated corpuscles, in stringy aggregations. MiNcus.
11. Irregularly shaped scales.  Epithelitnz.
12. Detached granulated corpuscles.  Puts.
13. Blood-corpuscles.  Blood.
14. Spermatozoa.  Semeen.
14*




CHAPTER XIII.
ON  POLARIZED  LIGHT.
" IF we transmit," says Dr. Brewster, " a beam of the sun's
light through a circular aperture into a dark room, and if we
reflect it from any crystallized or uncrystallized body, or transmit it through a thin plate of either of them, it will be reflected and transmitted in the very same manner and with the
same intensity, whether the surface of the body is held above
or below the beam, or on the right side or left, or on any other
side of it, provided that in all these cases it falls upon the
surface in the same manner, or, what amounts to the same
thing, the beam of solar light has the same properties on all
its sides; and this is true, whether it is white light as directly
emitted from the sun, or whether it is red light, or light of
any other colour.
" The same property belongs to light emitted from a candle,
Fig. 52.
0o. o.c.
C                       C
-B        -B
or any burning or self-luminous body, and all such light is
called commton light.  A section of such a beam of light will




ON POLARIZED  LIGHT.                   163
be a circle, like A, B, C, D, Fig. 52, and we shall distinguish
the section of a beam of common light by a circle with two
diameters, AB, CD, at right angles to each other.
"If we now allow the same beam of light to fall upon a
rhomb of Iceland spar, as in Fig. 53, and examine the two
Fig. 53.
A      -a
circular beams, O o, E e, formed by double refraction, we shall
find,
" 1. That the beams O o, E e, have different properties on different sides; so that each of them differs, in this respect, from
the beam of common light.
"' 2. That the beam O o differs from E e in nothing, excepting
that the former has the same properties at the sides A' and B'
that the latter has at the sides C' and I)', as shown in Fig. 52;
or, in general, that the diameters of the beam, at the extremities of which the beam has similar properties, are at right
angles to each other.
"These two beams, O o, E e, Fig. 53, are therefore said to be
polarizecd, or to be beams of polarized light, because they have
sides or poles of different properties.
"Now it is a curious fact, that if we cause the two polarized
beams, O o, E e, Fig. 53, to be united into one, we obtain a
beam which has exactly the same properties as the beam A, B,
C, D, Fig. 52, of common light. Hence we infer, that a beam




164               THIE  MICROSCOPIST.
of common light consists of two beams of polarized light,
whose planes of polarization, or whose diameters of similar
properties, are at right angles to one another."
There are other mleans of polarizing light besides that of
double refraction, just mentioned.  Me. iMalus discovered, in
1810, that a beam of common light, reflected fiom glass at an
angle of 560, or fromt water at an angle of 530 became polarized.
In order to explain the phenomena of polarized light when
produced by reflection from glass, let C, D, Fig. 54, represent
Pig. 54.
two tubes, one turning within the other. A, B, are plates of
glass capable of turning on their axis, so as to form different
angles with the axis of the tube.
If a beam of light, r s, from a candle or hole in the windowshutter, fall upon A at the polarizing angle of 56~ 45', it will
be reflected through the tubes, and will fall upon the second
plate, B, also at an angle of 56~ 45'. If, however, this plate
be so placed that its plane of reflection is at right angles to
the plane of reflection of the first plate, A, the ray of light
will not staffer reflectioln from  B, or will be so faint as to be
scarcely visible.  If we now turn round the tube, D, carrying
the plate, B, without moving the tube, C, the reflected ray, E,
will become brighter and brighter till the tube has been turned
round 90~, when the plane of reflection from B is coincident with




ON  POLARIZED  LIGHT.                   165
or parallel to that from A. In this position the reflected ray, E,
is brightest. If the tube be turned again, the light will grow
more and more faint, until another 900 are arrived at, when it
will again undergo reflection. Thus, changes will take place in
every quadrant of 90~ until the starting-point is again reached,
the ray of light being alternately faint and visible.
The same effect will be produced if we cause a ray of light,
R. Fig. 55, to pass through bundles of glass plates, A, B11, inFig. 55.
A        B
clined at the proper angle.  If the bundle of plates, B, be
placed as in the figure, the ray, s t, polarized by passing
through the bundle, A, will be incident on B at the polarizing
angle, and not a particle will be reflected, but it will be transmitted, as seen at v,w.  If B  is now turned round its axis,
the transmitted light, v iv, will gradually diminish, and more
and more light will be reflected by the plates of B, till, after
a rotation of 90~, the ray, v As, will disappear, and all the
light will be reflected.  Alternate transmissions and reflections
will thus take place in each quadrant, as in the former case.
lFor the ray passing through the tube in Fig. 54, or the ray,
s t, in the last figure, we may substitute one of the polarized
rays formed by double refraction in a rhomb of Iceland spar,
as seen in Fig. 53, or we may employ with even greater advantage the single image y 2rism of Mr. Nicol, who employed a
rhomb of calcareous spar divided into two equal portions, in a
plane passing through the acute lateral angles, and nearly
touching the obtuse solid angles. The cut surfaces having been
carefully polished, were then cemented together with Canada




166              THE MICROSCOPIST.
balsam, so as to form a rhomb of nearly the same size and
shape as it was before cutting.
By this arrangement, of the two rays into which a beam of
common light would be separated, only one is transmitted, the
other being rendered too divergent. Two of these prisms form
the usual polarizing apparatus of the microscope, being used in
the same manner as the bundles of glass plates, Fig. 55, just
described. One of the prisms is adapted to the under surface
of the stage, and is called the plolarizer; the other, called the
anal'ze'r, is placed above the eye-glass.
Dr. Brewster recommends that the analyzing prism be placed
immediately behind the object-glass, next the eye, having a
rotation independent of the body of the microscope.
Another method of polarizing light, is to disperse or absorb
one of the oppositely-polarized beams which constitute common
light, and leave the other beam polarized in one plane. These
effects may be produced by thin plates of agate, tourmaline,
&c.
Many persons employ a thin plate of tourmaline as an
analyzer in place of a Nicol's prism, and if its colour be not
objectionable, it may be used to advantage, as the field of
view is not so much contracted as when a prism is used. A
tourmaline of a neutral tint is an excellent analyzer.
The splendid colours, and systems of coloured rings, produced by transmitting polarized light through transparent
bodies that possess double refraction, are the most brilliant
phenomena that can be exhibited.  They were discovered
simultaneously by M. Arago and Dr. Brewster.
To see these colours:-having the polarizing apparatus so
placed that no light can be seen through it, place a thin film
of mica or sulphate of lime (between the twentieth and fiftieth
of an inch thick), so that the polarized beam may pass through
it perpendicularly.  It should be placed between the polarizer




ON POLARIZED  LIGHT.                   167
and the anal2yzer, as on the stage of the microscope.  If now
the eye is applied to the polarizing apparatus, as before, the
surface of the film of sulphate of lime, &c., will be seen
covered with the most brilliant colours. If the film be turned
round, still keeping it perpendicular to the polarized ray, the
colours will become less or more bright, and two positions will
be found, at right angles with each other, wherein no colours
at all are perceived.  If the analyzer be turned round, the film
retaining its position, complementary colours will alternate,
together with points of invisibility, during each revolution.
The colours of the film vary with its thickness, so that by
making grooves or lines of various depths, the most beautiful
patterns may be produced.  Drawings of figures and landscapes are thus executed, and being mounted between glasses
in Canada balsam, are invisible, or nearly so, till exposed to
polarized light, when they are seen distinctly, arrayed in most
gorgeous colours.
Various crystals exhibit, round their axes of double refraction, beautiful systems of coloured rings, often intersected by
a black cross. Complementary colours may be produced in
them  by turning round the analyzer.  In large crystals, as
rhombs of Iceland spar, certain angles must be ground down
and polished in order to exhibit the rings.
In those crystals having two axes of double refraction, a
double system of rings will be seen. A transverse section of
a prism of nitre will exhibit this phenomenon.
The great advantage of employing the microscope in viewing
the colours of crystals, &c., by polarized light, arises from the
fact that, when crystallized on a slip of glass, many of the
small crystals will be arranged with their axes of double refraction in the direction of the polarized beam. All such,
therefore, will exhibit colours, as will those also in which the
thickness of the crystal is not below the proper standard.




168               THE  MICROSCOPIST.
After the polarizing apparatus is adjusted, as before described, the crystals, properly mounted, may be placed on the
stage, in the same way as ordinary objects. Some few vegetable structures may be exhibited in the same manner, as the
siliceous cuticle of equisetunm, starch, &c.  Biany animal
structures, as feathers, slices of quill, horn, &c., are best shown
by placing a film of selenite or mica beneath them, by which
they become intensely coloured.  If the film be of unequal
thickness, the colours will vary.
"The application," says Mr. Quekett, "of this modification
of light to the illumination of very minute structures has not
yet been fully carried out, but still there is no test of differences in density between any two or more parts of the same
substance that can at all approach it in delicacy.  All structures, therefore, belonging either to the animal, vegetable, or
mineral kingdom, in which the power of unequal or double
refraction is suspected to be present, are those that should especially be investigated by polarized light.  Some of the most
delicate of the elementary tissues of animals, such as the tubes
of nerves, the ultimate fibrillm  of muscle, &c., are amongst
some of the most striking subjects that may be studied with
advantage -under this method of illumination."
To Prepare Crystals fo' Poclarized Li7ht. -  Pour a few
drops of a saturated solution of the salt on a glass slide
gently warm  it over a spirit lamp, so as to evaporate the
excess of fluid, taking care not to apply too much heat, lest
the water of crystallization be driven off and the salt become
opaque. The more slowly the crystallization is effected the
better.
The crystals should then be examined, and the best of them
mounted, either in the dry way (interposing a cell of paper,
&c., to preserve them from injury by the pressure of the glass
cover), or in Canada balsam. If it be desired to examine the




ON POLARIZED  LIGHT.                   169
crystals during their formation, the crystallization should be
carried on in a glass that is slightly concave.  All those crystals that are so thin as not to exhibit colour, may have colour
given them by placing a film of mica or selenite under them
on the stage of the microscope.
According to Mr. Fox Talbot, who first applied the microscope to the examination of polarized light, sulphate of copper,
crystallized from a solution to which a little nitric ether has
been added; oxalate of chromium and potash, from an aqueous
solution; and borax, crystallized in dilute phosphoric acid, are
especially beautiful.




CHAPTER XIV.
MISCELLANEOUS HINTS TO  MICROSCOPISTS.
ON CLEANING THE GLASSES.-"'When you clean the eyeglasses (a point of great importance to pure vision), do not
remove more than one at a time, and be sure to replace it before you begin another; by this means you will be sure to
preserve the component glasses in their proper places; recollect that if they become intermingled, they will be useless.
Keep a piece of well-dusted chamois leather, slightly impregnated with some of the finest putty or crocus powder, in a
little box to wipe themn with-for it is of consequence to preserve it from dust and damp; the former will scratch the
glasses, and the latter will prevent you from  wiping them
clean. As to the object-glasses, endeavour to keep them as
clean as possible without wiping, and merely use a camel's-hair
pencil to brush them  with; for wiping them hard with anything has always a tendency to destroy their adjustment,
unless they are firmly burnished into their cells."-Dr. Goring.
ON STOPPING FALSE LIGHT IN MICROSCOPE5s.-This is one
of the most important requisites in an instrument; for however perfect it may be, if there is the least light reflected from
the mountings of the glasses, or within the tubes, the fog and
glare produced will materially deteriorate their performance;
it is therefore necessary that all their surfaces be made as
sombre as possible.  The usual method of effecting this is to




MISCELLANEOUS HINTS TO  MICROSCOPISTS. 171
cover the parts while hot with a black lacquer, made by mixing lampblack in a solution of shell-lac in strong spirits of
wine.  A more elegant methodl, and better suited for delicate
work, is to wash the surface, previously freed from grease and
tarnish, with a solution of platina in nitro-muriatic acid
(chloride of platinum); after remaining on the work a few
minutes it is wiped off, the surface having assumed a deep
brown or black colour.  If these are not at handcl  a strong
solution of muriate of ammonia will answer for temporary
purposes.  Another method of stifling false light is by stops or
diaphragms in the body of the instrument; these have already
been referred to.
CABINET FOR MICIROSCOPIC OBJECTS. —The author of l Microscopic Objects" recommends a cabinet with shallow drawers-twelve of themn occupy a depth of four and a half inchesthe most convenient width from front to back being six inches.
Into these shallow drawers the slides containing the objects
are laid flat in double rows.  The outer ends of the slides are
made to fit into a ledge in the front and back of each drawer.
The inner ends of the sliders meeting in the middle of the
drawer are kept down by a very thin slip of wood covered with
velvet.  In this way the sliders do not shake when the cabinet
is moved from  place to place; every object is seen without
removal, and no loss of time is occasioned in making a selection.
Some persons have their sliders arranged edgewise, in boxes
made in imitation of books; the ends of the sliders being held
by a sort of rack. This may sometimes be convenient, but the
other form is preferable.
BREWSTER' S MIETIIOD OF ILLUMINATING OBJECTS. —Considering a perfect microscope as consisting of two parts, viz.,
an illuminating apparatus, and a magnifying apparatus, Sir
D. Brewster states, that it is of more consequence that the




172              THE  MICROSCOPIST.
illuminating apparatus should be perfect, than that the magnifying one should be so; and the essential part of his method
consists in this:-That the rays which form  the illuminating
image or disc shall have their foci exactly on the part of the
microscopic object to be observed, so that the illuminating
rays may radiate as it were from the object, as if it were luminous.  Now this can only be well attained by illuminating
with a single lens, or a system of lenses, without spherical or
chromatic aberration, whose focal length, either real or equivalent, is less than the focal length of the object-glass of the
microscope. The smaller the focal length of the illuminating
lens, or system of lenses, the more completely do we secure
the condition that the illuminating rays shall not come to a
focus, either before they reached the object, or after they have
passed it.
MODE OF OBTAINING THE-I  WIEEL ANIMALCULIE (V'o'rticelia rotatorni,).-"- Early in the spring I fill a three-gallon jug
with pure rain water (not butt-water, because it contains the
larvoe of the great tribe).  This qutantitylmore than suffices to
fill a half-pint mug, and to keep it at the same level during the
season. I then tie up a small portion of hay, about the size
of the smallest joint of the little finger, trimming it so that it
may not occupy too much room in the mug, and place it in the
water; or about the satne quantity of green sage leaves, also
tied and trimmed.  About every ten days I remove the decayed portion with a piece of wire, and substitute a fresh supply. A much greater number of animalcules are raised by the
sage leaves; but I have sometimes been obliged to discontinue the use of it, on account of its producing mouldiness. I
take them out with an ear-picker, scraping up the sides of the
mug near the surface (imncluding the dirt which adheres to
them by the tail), or under the hay or sage."-J. Fomord.
SUBSTITUTE FOR THE CONCAVE SPECULUM.-Mr. G. Jackson employs a plano-convex lens of about two inches in diame



MISCELLANEOUS  HtINTS TO  MICROSCOPISTS. 173
ter, and of four and a half inches focus, silvered on the plane
side, and backed with a plate of brass.  This lens, when so
treated, becomes a reflector of about two and a quarter inches
focus, and forms one of the best instruments that can be desired for throwing light upon an object viewed as opaque. We
have used such an arrangement for some time in place of the
concave mirror, and deemed it peculiar to ourselves till reading
an account of the above.
APPARATUS TO PREVENT TILE EVAPORATION OF LIQUIDS
UNDER THE MICROSCOPE. —apours arising from the liquids
under observation would, by condensing on the under surface
of the object-glass, form there round drops, which act as so
many lenses, and which, arresting the rays of light in their
progress, would scatter them in every direction, and thus completely destroy the image before it could reach the object-glass.
This effect takes place not only when the temperature of the
liquid is raised by the application of heat, either directly or
in consequence of chemical action, but also when, in studying
any body by the microscope, a fuming acid is used, such as
the hydrochloric.  This inconvenience  is prevented by enclosing the frame of the object-glass in a small glass tube, shut
at one end, whose inner surface is closely applied to the surface
of the object-glass.  This end is then plunged into the liquid,
which is thus prevented from either beclouding the surface of
the lens or finding its way into the interior of the microscope
and there producing the same effect.-Rasypail's Organic
Chenistry.
DROPPING TUBES, for placing on the object-holder or slide
any reagent whose action is to be examined, may be easily
made by softening a piece of glass tube in the flame of a lamp,
and drawing it out till it becomes capillary, after which it may
be broken to a convenient length. Fishing-tubes for animalculse may also be made in the same way.
1.6'




RESULTS OF DR. GRUBY'S OBSERVATIONS ON PATHOLOGICAL MORPHOLOGY.                                                  -
TIANSLATED BY S. J. GOODFELLOW, M. D.
A. OF MUCUS.
Healthy mucus and nucus generated by irritation and normal inflammation, are composed of an amorphous
ductile substance (proper muceus), globules, and epithelium.
Icus PRODCED BY N- MUBICUS PRODUCED BY        MUCUS PRODUCED BY A  MUCUS PRODUCED FROM
HEALTHEY MUCUS.      MAL IRRITATION         SLIGT NORMALINFLAM-   MIOE INTENSE NORMAL    CHRONIC NORMAL INMATION.                 INFLAMMATION.          FLAMMATION.
Very few globules      Very few globules      Globules more nume-  Globules very nume- Globules very abundant
rous                   rous
Much of an amorphous  Very much of proper  Less mucus                Much less mucus         Very little mucus'         2
substance (proper      mucus
mucus)
Contains but little epi-  Contains but little of  Contains more epithe-  Contains very little epi-  Contains verylittle epithelium                epithelium             lium                   thelium                thelium
Globules from 2-4times  Globules from 4-5 times  Globules 6-8 times lar-  GlobLlesfrom 6-8 times  Globules 6-8 times larlarger than the blood    larger than the blood    ger than the blood    larger than the blood    ger than the blood
particles              particles              particles              particles              particles
No molecules, or the  The smallest molecules  The smallest molecules  Filled with the small-  Filled with the smallsmallest, fill the glo-   fill the globules   (filled with), and a    est molecules and a    est molecules and a
bules                                         central vesicle        central vesicle        central vesicle
Very thin envelope to  Very thin smooth en-  Smooth envelope         Smooth envelope         Smooth or no envelope
the globules           velope
Not changed in water   Globules swell in dis-  Swell in distilledwater  Globules swell in dis-  Swell in distilled water
tilled water                                  tilled water
Envelopes easily broken  Envelopes easily'broken  Envelopes easily broken
in water




X~i'         UV.L tuJNJlLjN'        UN l                       -AlV
0NORMAL MUCUS, OTHER FORMS.
MUCUS GENERATED FROM TUBERCULOUS IN-              DYSENTER   MUCUS.                    MUCUS OF URTHRAL BLENNORREA.
FLIAMMATION OF THE LUNGS.
Besides the products of catarrhal in-  Contains globules with central vesicles   Contains from the beginning a very few
ammation contains yellow lenticular     and molecules, round or ovate greenish       loules exceeding four times the diaspheres 1-8 times larger than the glo-    corpuscles endowed with the smallet    meter of the particles of th  blood, and
bus of pus, concentrically  striated,    molecules, symmetrically disposed, and     provided with the smallest molecules
composed of concentric lamelle, which  also products of catarrhal inflamma-    and an envelope
are dissolved in caustic potash         tion                                      On the third day it is compos  of many
They are in-                                                    gloules, the smallest molecules  an
In nitric acid     I creased 5 timesenvelope, and etral vesicle
- solution of nitrate of- in volume and                                            On th  tenth day   l the vesicles are ensilver               become transpa-                                                dowe  with central vesicles
rent                                                           They swell and arent  easily boen inwater
Some pulmonal cells and muscular fibres                                            On the fortieth day very few globules are
are seen in it                                                                      found
1. OF PUS.
Pusis composed of a certis  white pelhicid fluid and globules; sometimes othe' substasces are mixed with these.
PUS GENERATED MY NORMCAL INFLAMMATION.0
PUS FROM A RECENT WOUND. PUS FROM ARECENT AnSCESS. PUS FROM AN OLD AnSCESS. Pus FROMI AN OLD WOUND. PUS FROMN THEOSURAE COFTI
NUTTY IS UNIN5JURED.       0
Few globules              Many globules             Many globulss              Fewer globules            Fewer globules0
Contains more fluid       Contains but little fluid  Contains but little fluid  But little fluid         Mc  li
Globules from 4-6 times  Globuales -1- times lar ger  Globules 3-4I times larger  Globules 1'-4: times larger  Globules S-S times larger
larger than those of    than those of the blood    than those of the blood    than those of thG blood    than those of the blood
the blood                                                                   Contains a good deal of  Contains but little epiepitheliumn               thelium
With very small, and lar- With very small, and lar-  With very small, and lar- With very small, and lar-  With very small and larger molecules             ger molecules             ger molecules             ger molecules              g-er molecules or none,
Hlave one central vesicle  One or two central vesi-  With a central vesicle    No central vesicle        composed of a central
and an envelope           clss, seldom  without                                                          vesicle full of molecuone                                                                           leo, or none at all in it
Globules swell, and en-  Globules swell, and en-  Swell but little in dis-  Does not swell in die-  Sometimes swell in disvelope bursts in dis-    velope broken in dis-   tilled water                 tilled -water              tilled -water
tilled water              tilled water




PUS FROM  SPECIFIC INFLAMMATION. 
1. GENERATED DURING THE VARIOLOUS PROCESS.
2. GENERATED IN THE TUBERCULOUS PROCESS.
A. DURING THE FORMATION OF    B. DURING THE FORMATION OF    C. DURING THE FORMATION OF
PAPULE.                         VESICLES.                       PUSTULES.
The pellucid fluid  extricated  On the 4th day a little limpid  Onthe 6th day the thicker yel-  See-Mucus produced from 
offers an alkaline reaction     serum                            low  fluid has but a slight        Specific Inflammation. 
Is composed of a white pellucid  Contains globules endowed with    alkaline reaction
fluid and a few free molecules    the smallest and larger mole-  The globules 4 times larger than
of the larger and smallest    cules, and a central vesicle       those of the blood, many with
kind, and animalcules         The envelopes are not easily    an  envelope  easily  to  be 
On the third day after the erup-    broken                         broken or without one
tion larger molecules and a  Vehement molecular motion         Filled with the smallest or the 
few  white almost pellucid  Animalcules, and free  very    larger molecules, and some- 
globules 2-3 times larger than    small globules                 times provided with a central
those of the blood            On the 5th day the turbid serum    vesicle 
Filled with the smallest mole-    has an alkaline reaction       The molecular motion  dimicules                         Contains globules of the larger    nished 
Molecular motion scarcely to be    yellow molecules              On the 7th day and beyond, 
seen                          The envelopes are easily broken    the yellow  thick fluid conAnimalculn are found in it      The molecular motion and ani-   tains many globules adhering
malcules are well seen          together
The envelopes are very easily
broken, the molecules dissipated without order
Cells of epithelium and drops
of fat are frequently seen in
it
N.B.-In some individuals the globules are 3-4 times larger than those of the blood, perfectly or partly empty, also spheres
twice or six times larger than the pus globules, consisting of smaller spherules.




C. OF SEROUS EXUDATION.
WITE, OR  REENISH-WHITE, LIMPID, EXUDATED, SEROUS FLUID IS COMIPOSED OF A PELLUCID FLUID AND   LOBULES.
~SERO~U S EEXDA- SERO     EuD- SEROUS EXUD.A- SEoUS EXUDA- SEROUS EXLDA- SRROUS EXUDA- SOUS EXUDA- SEROS ExUDAION OF A BLAD- TION FROM CRUDE TION EXTIRICATED  TION EXTRACTED  TION FROMI A HY- TION FROM (DE- TI   EXTRACTED  ION FROM THE
ER RODUCED     INFILTRATION OF FROM THE PAPU- FROM  THE  FI- DROCYST.           MA OF THECUTIS. FROM          SU- VAGINAL ISE~LISTER   INTESTINAL  TY- LIE OF MODIFIED  ERINE OF A VIL-                                      STANCE OF AN IN- CHARGE ON THE
US.           VARIOLA.          LOUS HEART.                                        FLAM   HUMAN  TIRD  ERIOD OF
FLACENTA.       F -ENANCY.
Contains whit  Contains white  Contains white  Contains white  Contains  per- Containswhite, Contains whit  Contains white 
gloules with   globules with   globules with   globules, con-   fectly  round   or yellowish-   gloules, with   globules, with
a  very  thin    envelope   a very  thin   sisting  of a   white globules   white  stella-   an         velope   an   evelpe 
overig flled   filled with the   covering filled   very thin en-   destitute   of   ted  globule,    led with the   filled with the
with the small-  smallest mole-  with the small-  velope, filled   molecules    scarcely larger   smalletmole   smallest molest molecles,    les          est molecules    with the small- Scarcely larger   than those of   cules              ule
or destitute of 1-2larger than  1-4timeslarger   est molecules    than the glo-  the blood      -2tieslarger Once to twice
all covering  the blood glo-  than the blood  1-2 timeslarger   bules of the  Here and thre   than those of  larger  than
1-2 larger than   bules       globules         than those of  blood              provide  with   the blood         the blood disws
~~the blood glo-   ~the blood                                           a  small nu~~~~~b nu~~~~~~~~~~~~~~les                                      cone____ ___ ___lesus
D. THE MORPHOLOGY OP THE GLOBULES GENERATED DURING THE PATHOLOGICAL PROCESS.
1.THOSE WHICH OCCUR FE MTUCOUIS MIEMBRANE.
Ie HEALTHY MIUCOCS SeEM-    IN IRRITATED MUCOUS    IN SLIGHTLY IRRITATEH MU-  MNATO noF MUCOUSE  MELM- IN CHIRONIC INFLAMMSATION
BRANE.                   MEMBRANE.               CODES MEMBRANE.          MTNOFUCS   M    OF A MUCOUS MEMBRANE.
DEItA NE.
Very few yellowish-white  Very few yellowish-white  More copious or abundant  The yellow~ globulee are  The yellow globules a-re 
globules are generated    globules are generated    yellowish-white globu-    generated  in  greater    generated in the grreatprovided with a cover-  They are provided with    lee are generated- They    abundance, S times lar-    cot abundance, are S
ing, and enclosing none    an envelope, enclosing    are, provided with an        ger than the blood glo-    times larger than the
or very few of the email-   the smallest molecules,    envelope, filled with the    bules, endowed with an   blood globules, endowed
er moleules                and are 4 times larger    emallest molecules and    envelope,'fihlld with the    with  an envelope, or
They are -not changed in    than the blood globu-    a central -vesicle, and    smallest molecules, and    an envelope with the
water, and are from 2-4    lee, and swell in water    swell, and are broken       a central vesicle          emalleet molecules, and
times lareor than those                               in water. They are S  They swell, and are bro-    a central vesicle
of the blood                                          times larger than the    ken, in water
blood globulees____________




2. THOSE WHICH ARE GENERATED IN THE SKIN.
BY THE APPLICATION OF A  BY THE VAPRIOLOUS PROCESS  BY THE VARIOLOUS PROCESS  BY THE VARIOLOUS PROCESS  BY THE VARIOLOUS PROCESS
BLISTER.            UNDER THE FORMATION OF   DURING THE FORMATION OF    DURING THE FORMATION OF   DURING THE FORMATION OF
PAPUL] -.                  VESICLES.                  PUSTULES.                   CRUSTS.
A very few white globu-  A very few white globu-  Numerous    yellowish-  Very  numerous yellow   A few yellow whole gloles, 2-3 times larger    lus, 2-3 times larger    white  globules,  3-4    globules, 4-5 times lar-    bules, 4-5 times larger
than the blood globu-    than those of the blood,    times larger than those    ger than those of the    than those of the blood:
les, endowed with no    pellucid, endowed with    of the blood, endowed    blood, provided  with             many  lacerated, furenvelope, or one filled    a very thin covering,    with an envelope, filled    the smallest andlarger    nished with no envewith the smallest mole-    enclosing the smallest    with the smallest and        molecules, and the cen-    lope, or with one filled 
cules                      molecules                  larger molecules, and a    tral vesicle                with the different mole- 
Water does not change  They swell in water              central vesicle           They swell in water, and    cules 
them                                                They swell, and are bro-    are easily broken          They are easily broken
ken, in the water 
3. THOSE WHICH ARE GENERATED IN SEROUS MIEiIBRANE.                                                        2
O TIRE PERICARDIUM UNDER   OF AN INFLAMED PERITO-    OF AN INFLAMIED PERITO-         OF A VERY ACUTELY
]~IYDl%0CYSTS. THXE FORI~ATION 0F THE[
HvDROOSvTS.     THE FORMATION OF THE                NEUM.                  NEUMI NEONATI.         INFLAMED PERITONEUM..
VILLOUS HEART.
White, pellucid, perfectly  White globules, 2-3 times Yellowish-white globules, Yellowish-white globules, Yellow globules, 4-8 tinmes
round globules are form-  larger than those of the   3-6 times larger than   4-S times larger than   larger than those of the
ed, scarcely larger than   blood, endowed with a   those oftheblood, formed   those of the blood, cornm-  blood, either with avery
those of the blood, with   very thin envelope, filled   with an envelope, filled   posed of a very fine en-  thin envelope partly or
an envelope destitute of  with the smallest mole-  with  the smallest and   velope, with a few very   entirely filled with the
all molecules              cules                      larger molecules           small molecules or none,  smallest or larger moleThey are not changed in  They swell in water          They swell in water          and with a central vesi- cules, or with no enve~~~~~~~~~~~~~~~water   ~~~cle, either filled with the   lope
wateri~~~~~~~ ~smallest molecules, or They are not changed by
possessing none            water
They are not changed by
water




TIIHOSE WHICE ARE GENERATED  IN  PATHOLOGICAL  (DISEASED) PARENCHYMA.
OF CRUDE, RECENT INFILTRATION  OF THE RED INFILTRATED MIESEN-  IN THE PROCESS OF PURULENT IN-   IN THE SOFTENED  MESENTI
OF THE ILEU.        TERIC GLANDS IN ABDOMINAL    FILTRATION OF THE CELLULAR    GLANDS IN ABDOMINAL  TYPI
TYPHUS.                           TISSUE. 
The globules are white, diapha- Yellowish-white diaphanous glo- Roundyellowish-white globules, Round yellowish-white globules
nos, scarcely  exceeding the   bules exceeding from  2-4 the   exceeding 4 times the magni-  4-8 times larger than those of 
diameter of the blood globules,  globules of the blood, composed   tude of those of the blood, com-   the blood, composed of an enwith a smooth envelope filled   of an envelope filled with the   posed of an envelope filled with   velope with  the smallest or
with the smallest molecules   smallest molecules, or 6 times   the smallest molecules             larger molecules
11They swell but little in water  larger than those of the blood, They  swell but little in water   They swell in water
with an envelope filled with 
the smallest molecules and a
central vesicle, are many molecules
IN THE EXUDATION OF PLASTIC
ATIZED 1RECENT PLACE                                               LYMPH IN CROUP.
LYMPH IN CROUP.
White globules scarcely exceed-                                     Round yellowish-white globules
ingrthose of the blood, composed                                    exceediog 38 or 4 times the size0
of an envelope, filled with the                                     of those of the blood, composed
smallest molecules                                                  of an envelope filled with very
small molecules
____________________________                       ~~They  are  -not changed  by  water________
Os A HEPATIZED SPLEEN.
White globules equalling in
magnitude the globules of the
blood, or twice as large, with
or without an envelope, but if
with one it is filled with the
smallest molecules
They are not changed by wateT




THOSE WHICH  ARE GENERATED  ON THE SURFACE OF A PATHOLOGICAL (DISEASED) ORGAN.
oo
EXP   SED.
IN TE TNTH    OF A  EENT  OF   S OF A RECENT WOUND 2   OF PUS IN THE SEVENTH WEEK OF  FROM'AN OLD WOUND SUPPURATING
WOUND.     MOURS AND BEYOND.                  A RECENT WOUND.                     BUT LITTLE.
A few round, white, tranparent   ound  yellowish-white  abun-   ery numerous round yellowish  A few yellow roundish globules
globules 1-3 time  larger than   dant globule 4-6 time larger   globules 5-8 times larger than   2-4 times larger than those of
thse of the blood, composed of  than those of the blood, en-  those of the blood, composed of  the blood, composed of a dense
a very thin envelope filled with   dowed with a very thin enve-   an envelope with the smallest  envelope full of the smallest
th  smallest molecules  lope with the smallest and the   molecules and a central vesicle   molecules
They swell but little in water  larger molecules, and also a They swell and their envelopes They are not changed by water
central vesicle          are broken in water
They swell in water               _________
SHUT.
A~sCESSUS IDIPATHICI RECENIS-  OF IDIOPTHIC ABSCESS F THE                OF AIIETASTATIC AB3SCESS OF SIX
SIMI FRELI AEDOMINALIS.                  LIVER.                Or, AN OLD IDIOPATHIC ABSCESS.          DAYS' STANDING 
Round or oblong yellow globules  Round  yellow  globules  3 - 4 Yellow round globules 4-6 times  Hound globules 1-3 times larger
4-6 times larger than those of  times larger than those of the   larger than those of the blood,  than those of the blood, com.the blood, composed of a very   blood, composed of a thin enve-  composed of a, very thin enve-   posed of the smallest molecules,
thin envelope, -with the very   lope full of the larger and a   lope, endowed with the small-   but seldom of an envelops
small and larger molecules,  few of the largest molecules        set molecules: soms have no  Are not changed by water
either with or without a cen- They are changed but little in   envelope
tral. vesicle, or a simple or   water                            They swell in water
double one
They swell in water and their
envelopes burst                                                  _______________




COMIPARISON BETWEEN  BMUCUS AND  PUS GENERATED FROM  N0ORMAL INFLAMMIATION.
=~~~~~~e n  mo   0,  5s p~5  CCC.< Sme   
bloo~   6    S Coi-hit sSL~- osil Sn Is  ~lh.    P~a-f:  PDs- IQuick<  Corru- Corru-|Gerru-| First |No  |No  |  oi- |Con
a Itimes   o~r          or i   err  1 i- l s    j  s  solves ly die-  gates  gates   gates    dio-  change changle olves tra'r,      mlarger-cellowi  ao ub.e  mall -',obe  }the en -! the en- solves the en-I the en- the glo- ool es,the   the
~         than i"          I            and  broreri'~elope s velopes the en -velopes'velopes bules, the en-                 globu- gloh
m              d! the  ladthe! and  velopes,          and   velopes,                 ies;   is
a   t of thlne  ] j!      I la~oze^      E rery  6 ti-e    the!                 tinges   more                    the
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I- the;   g blood   S'      |              l snlail | very   wlte |        |        them   slowly                  white
mole-  sos 11  vesicle                  of a    the                    mu0  i                                                      csles  mole- remain,         yellow   very                    cous
c;: l   l  l  l'      N      I  -    ~rciles.   i                     colour  small                   fluid 
gRou-od I       I~hitc Smoot]-II s  in-le Th         D I t     is-   Quick- Corru- Corru- Co         First   No    No imole  r- e-    nand                          ~~~~0
of tire           ar-er       Ivery    thcl~   theu                    tingesrmo   morms                th




V   i i.            Q     0 |~
e-dis-    the  the -the    glo-                            the    the
0  C                                     0~~~~~~~~~~~~~~0
a,  Round  3-4  White ~~~ SmohOeoEh -y-De                  i- Vr    or-Cro or- Ro-                      N        o    Di       o
hal m an   ep,         es  solves  enve-enve- globu-  bules                      glo-  globuthosenoc  tI..ente2-t  2-5  the loe   l               Gopes l pe and trane-Pb.lse,  lee
5 00~~~~~~~~~~~~~~~~~~~~~~~~E: 
Rond34h                hteSoohOn rdh                 rnemaDin remin  VoperyCru              themu  a the eon-              muN Ds   form    Z
loglogryelwnoea --                   l    Ial          Proth e- throe-   Pro-  torm   torm    orme    igo                  log    th
thn      al    AJuad        cr- eoes. duelps ducves  enode-  enofi- nlobul- nodla-                     glCgo
those     none  the  k note2 h no5  noe  montes  monte  mesandtr mnts-                             uel
~~ ~.... —...                change change change                              ___K..  _ __ _tine___l~us   flud   1cc ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~rmi-                                                       rean nce




INDEX.
A.
Achromatic object-glasses, their invention an epoch in histology, 18
description of, 34
Animal tissues, to be examined while fresh, 17
on procuring, 73
Accessory instruments, 40
Animalculn cage, 37, 48
Asphaltum cement, 58
Agate, 64
Algam, 71
Aphides, 82
Acari, 82
Anatomical preparations, 85
Areolar tissue, 92
Artificial star, as a test object, 99
Angle of aperture, explained, 100
Arm rests, 107
Albuminous urine, 144, 157
Alkaline salts in urine, 147
Advantage of polarized light in examination, 168
Apparatus to prevent evaporation, 173
B.
Bog iron ore, from infulsoria, 14
Borelli, his observations on pus, &c., 15
Blood corpuscles, 85
Blood discs of siren, 86
Bone, 86
Basement membrane, 92, 93, 116




184                           TNI)EXn
Bat's hair, 102
Branchial cartilage of tadpole, 120
B31ood in urine, 144, 155
Bile in urine,.156
Brewster's mode of illuminating objects, 171
C.
Causes of error in observation, 15
Coal beds, from vegetation, 14
Coddington lens, 29
Compound microscope, 31
defects of the comon, 3
improvements in the, 3
mechanical conveniences necessary to the, 5
forms of the, 3
most celebrated makers of the
Smith and Beck's, 6
efforts to reduce t   price of te, 8
Condenser, 37, 40, 49, 50
Condensing (or bull's-eye) lens, 37, 42, 50
Camnera bIacida, 387, 45
Compressorium, 48
Cook's preserving fluid, 54
Cooper's preserving fluid, 54
Chloroform a)s a preservattive, 56
Cells for mounting, 59
Cements, 58
Canada balsamn cement, 59
Charring vegetable matters, 59
Carbonate of lime, 64
Crystallization of salts, 64
water, 65
Cuticles, 66
Cellular tissues, 67
Charcoal, 69
Circulation in vegetables, 72
Corals, 78
Circulation of blood, 86




INDEX.                            185
Capillaries, their functions, 95
of skin, 89
of mucous membrane, 94
Crystalline lens in fish, 90
Ciliary processes of the eye, 90
movement, 94
Chromatic aberration, 33
mode of observing, 98
Circulatory system of insects, 112
Chemical constitution of organized bodies, 115
Cell-growth in a meliceritous tumour, 121
Classification of animal tissues, 121
malignant growths, 127
Carcinoma, 129
Cheinico-gelatinous injection by Dr. Goadby, 139
Cystine in urine, 153
Colours exhibited by polarized light, 166
Cleaning the glasses of microscopes, 170
Cabinet for microscopic objects, 171
D.
Dissecting microscope of Mr. Slack, 27
Dark wells, 37
Diaphragm, 37, 40, 49, 51
Deut-ioduret of mercury, 65
Dissecting needles, 106
troughs, 106
Digestive system of insects, 111
Development of cells, 116
a.nimal tissues, 119
Diabetic urine, 144, 157
E.
Erector, 36, 42
Entozoon folliculorumn, 82
Epithelium, 92, 93
Examination of morbid structure, 124
its importance, 126
16i.




186                          I N 1) E X.
Encephaloid, 131
Earthy phosphates in urine, 143, 148, 159
Eyes of animals, 90
F.
Fossil remains determined by the microscope, 1.4
Fontana, histological observations of, 17
Frog plate, 46
Fishing tubes, 48, 173
Fossil wood, 69
Ferns, 71
Fibrous and arcolar tissue, 92
Forms of nuclei, 118
Form of fibrous tumour, 127
G.
Geology, use of microscope in, 13
Goadby's fluids, 55
Gum mastich cemnent, 59
Gannal process, 54
Glycerine, 54
1.
Histology, created by the microscope, 14
RIewson on the blood globules, 17
Herschell's doublets, 29
Holland's triplet, 31
Huygenian eye-piece, 34
Hairs, down, &c., of plants, 69
Hlard tissues, 71
Hair of animals, 85
Horn, hoofs, quills, &c., 85
Human blood, 86
Hair of Dermestes, 102
Hippuric acid, 1.46
Importance of the microscope to zoology, 14
Inorganic objects, 64




INDEX.                              1.87
Illuminating, lamp, 43, 50.
Iron pyrites, 65
Infusoria, classification of, 74
on procuring, 75
to observe the strucGture of, 77
fossil, 77
Insects, antennn3 of, 78
eggs, 79
elytra, 79
eyes, 80
feet, 81
hairs, 81
mouths, &c., 81
parasitic, 82
trachea, 83
stings, ovipositors, &c., 83
internal anatomy of, 109
Injected papillse of skin, 90
preparations, 94
Instruments for minute dissection, 105
Internal anatomy of insects, 109
Injecting materials, 134, 137, 138, 141
Instrument for diagnosis of tumnours, 138
Injection of the lymphatics, 142
Japanner's gold size, 58
K.
Kiesteinll 144
L.
Lenses, different for ms and effects of, 22
simple mode of making, 28
imperfections in, 29
Lewenuhoeck, his discoveries, 16
Lieberkuhn, his anatomical researches, 17
concave reflector, so called, 44
Lamp-black cement, 59




188                          I NDEX.
Lichens and fungi, 72
Loaded corks, 106
Lepisma saccharina, 103
M.
Malpighi, microscopic researches of, 15
Modern observers, 19
Medico-legal inquiries with the microscope, 21
Micrometer eye-piece, 35
Magnifying powers, hints respecting, 49
table of, 23
to obtain the power of a compound microscope, 46
Mirror, use of the, 50
Management of the light, 50
Mounting transparent objects, 53
in the dry way, 53, 54, 61
in fluid, 57
in balsam, 59
Marine glue, 58
Mounting cellular structures, 60
opaque objects, 61
crystals for polarized light, 630, 168
Mosses, 71
Muscular fibre, 91
Mucous membrane, 92, 903
Mouse hair, 102
Morpho Menelaus, 103
Muscular system of insects, 113
Morphology of pathological fluids, 1033, 174
Method of injection, by Ruysch, 138
Rlanby, 138
Monro, 138
Professor Breschet, 138
Mv. Doyere, 139
Dr. Goddard, 141
Mucus in urine, 1.55
N.
Nervous structure, examination of, 91




INDEX.                              189
Nerves and capillaries of muscle, 91
Nervous system of insects, 112
0.
Organic remains in limestone, 14
Optical illusion to be guarded against, 17
Opaque objects, mounting of, 61
how viewed, 51, 52
Mr. Brooke's mode of viewing, 45
Oolites, 65
Organic fibres, 72
Oxalate of lime in urine, 1438, 150, 159
P.
Polarizing apparatus, 41
Preparation of glass slides, 54, 57
Preserving fluids, 54
Pollen, 69
Pigment cells of skin, 80
of the eye, 90
Pontia brassica, 104
Podura plumbea, 104
Proximate principles, 115
Primary form of organic matter, 115
Pus in urine, 144, 155
distinction between it and mucus, 125
Polarization of light, 162
Q.
Qualifications of a microscopist, 18
it.
Religious sentiment, microscope conducive to, 18
Reflecting mnicroscope superseded, 38
a curious form of, 38
Rules for microscopic observations, 49
Raphides, 71
Retina of the eye, 90
Respiratory system of insects, 109




190                          INDEX.
Simple microscopes, construction of, 23
magnifying powers of, 23
mode of mounting, 23
form of, for opaque objects, 26
Stanhope lens, 29
Silver cup or Lieberkuhn, 87, 44
Side reflector, 37, 44
Stage micrometer, 46
Size of glass for mounting, 58
Sealing-wax varnish, 58
Sand, 65
Sections of granite, &c., 65
coal, 65
wood, 68
Siliceous cuticles, &c., 69
Starch, 70
Seeds, 71
Sponges, 78
Shells of mollusca, 83
Scales of fish, 84
Skin, 89
Spherical aberration, 33, 99
Scales of insects, 103
Shells of infuLsoria, 104
Swanmmerdani's scissors, 105
mode of dissection, 107
Secondary organic compounds, 115
Scrofulous growths, 127
Syringe for minute injection,.135
Stopping false light in microscopes, 170
Substitute for the concave speculum, 172
T.
Trough for chara, &c,, 36, 48
Thin cells for delicate tissues, 57
Teeth, 88




INDEX.
Theory of life and sensation, 96
Test objects, Dr. Goring's discovery of, 98
character of, 102
Tinea vestianella, 103
Tables for examination of urinary deposits, 159
of results of Dr. Gruby's observations, 174
U.
Utility of the microscope in medicine, 19
Urinary deposits, 143
Urea, 145
Uric acid, 143, 145, 159
V.
Vegetable physiology, microscope indispensable in, 14
Varley's dark chamber, 41
Vegetable tissues, dissection of, 66
Vascular tissue in plants, 67
Vitality and electricity not identical, 96
Valentin's knife, 106
Vital principle, theories respecting the, 96, 114
W.
Withering's Botanical Microscope, 33
Wilson's Pocket Microscope, 24
Wollaston's doublet, 30
condenser, 41
Watch-glasses useful, 48
White fibrous tissue, 92
Wheel animalcule, mode of obtaining, 172
Y.
Yellow fibrous tissue, 92
Zoophytes, 78




No. 48 CHESTNUT STREET, PHILADELPHIA,
Have for Sale a very large Assortmrent of
COMPOUND  Wq OROS.OPES.
Neatly mounited in Brass, of a power ranging from 15 to 60 diameters, from                                           $2 50 to $10
An Achromatic Microscope, cylinder brass body, with rack-work
and condenser-power 50 times.  Price,                       $16 00
Ditto, with power ol 120 to 135 times,                   $22 and $23
A still better Microscope, also Achromatic, to screw upon top of
the box, which makes it firmer-large stage, rack-work, condenser, dissecting instruments, &c.-power 120 times. Price, $26 00
The same Instrument, with extra Lenses, so as to increase the
power from 160 to 250 times.  Price,              W33 00 to $37 00
The very best Achromatic Microscopes, with movable lever or
rack-work stage-ilicroscope to be placed either vertical or
horizontal-bull's eye condenser-frog plate, &e.; cost from
~1'0 to,$650
Sets of Achromatic Lenses, of various powers,. separllte from the
Microscopes,                                $4 50 to ~9 00 per set.
Eye-pieces, of various powers, separate from   the Microscopes,
{2 25 to $3 O00 each.
Glass slips for Mlicroscopic slides or preparations,    50 cts. per doz.
Glass dishes and covers for Microscopic slides, and wet preparations,                                     $1 25 to $3 00 per doz.
Thin glass for covering Microscopic objects.
Microscopic sliders, in sets of 12, 24, and 36, of portions of insects, sections of wood, guano, feathers, &e.  Prices from
$2 to $6 50 the set.
Finely prepared objects, parts of insects, &e.,   19 to 50 cents each.
"     "       "    anatomical as injections,      75 cents each.
Also, Magnifying Glasses in horn cases, for the pocket; Microscopes
to examine the ear; Urinometers, I Thermometers, Hydrometers,
Weighing Scales, Magnets, Mathematical Instruments, Spy -GTlasses;
Camera L, lidas, Stainhope Lenses,  n.