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LINDSAY &  BLAKISTON,  PUBLISHERS. PHILADELPHIA. 
w 
 
THE  MICROSCOPIST. 
THE  CURIOSITIES  OF  THE  MICROSCOPE
ILLUSTRATIONS  OF  MINUTE  PARTS OF  CREATION.
                                  WITH
                MOTEG3®(!!JQ DILILIBISTiSATJ'O®!!!!©-

          BY  THE REV.  JOSEPH  II.  WYTHES, M.D.
                  AUTHOR OP "THE MICROSCOPIST," ETC., ETC.

     "Every grain of sand is an immensity—every leaf a world,"—Lavater.

                A neat  16mo. volume.  Cloth, gilt,  $1  00.
  "This is a beautiful little book—beautiful in its printing, its colored plates, and
its whole getting up, and is well adapted to instruct and amuse those for whom it is
intended.  There  are twelve plates, containing numerous figures, drawn with much
care, even  to minute details.  The spirit of the work is excellent, and we wish it in
the hands of all the children of the land."—SiUiman's Journal.

  "It communicates substantial knowledge in the most entertaining way, and opens
to the young intellect the whole subject  of  natural philosophy.   The colored  en-
gravings greatly  illustrate these instructions.   We haye  seen no book written  for
young  people that we  can  more cordially recommend."—Christian  Advocate and
Journal.

  "The revelations of the microscope are truly astonishing; and the effort to unveil
the minute parts  of creation visible to youthful eyes by its amazing power, is worthy
of praise.  The style of this volume is adapted to the class for which it is prepared!
and the numerous illustrations, beautifully colored,  not only add to its beauty, but
also to its usefulness."—Recorder.

  " The style of the book is simple, yet comprehensive;  and there are few men and
women who will not, as well as the young, find pleasure and instruction in its pages.
The colored plates, showing the  appearance of a variety of things, animate and in-
animate, as they  appear when subjected to the microscope, are well  executed, and
form not the least attractive feature in the volume."—Home Gazette.

  "For children who have any germs of a taste for scientific investigations, this little
book would be highly attractive, and would encourage in all whom curiosity might
tempt to its perusal, that love of Nature which forms one of the purest and richest
sources of pleasure through life."—Saturday Post.

  " No more beautiful present can be given to our children, nor one better calculated to
enlarge their views of the wonders of creation.  It will also furnish much knowledge
to children of a larger growth."—State Banner.

                       LINDSAY  &   BLAKISTON,
                                                             Publishers. 
 
PLATE- 2
T Smdairs ItA.'i 
THE
     MICROSCOPIST:
                OR,       vii    »
         %  (fcnntiiUh Hlitittntt;*
               ON THE       V.

USE  OF THE MI CEO SCOPE:
       PHYSICIANS, STUDENTS,

              AND ALL

   LOVERS OF NATURAL SCIENCE.

SECOND EDITION, IMPROVED AND ENLARGED.

         WITH ILLUSTRATIONS.
JOSErH H. WYTHES, M.D.<V^'
                   vi:
       PHILADELPHIA:
LINDSAY AND  BLAKISTON.
         LONDON:
     TRUBNER & CO.
          1853.
v ^_______ I 
            Entered, according to Act of Congress, in the year 1853,





                      BY LINDSAY AND  BLAKISTON,





In the Clerk's Office of the District Court for the Eastern District of Pennsylvania.
C. SHERMAN, PRINTER. 

                  TO

      PAUL  BECK  GODDARD, M.D.,
              DISTINGUISHED BY
HIS ARDENT AND SUCCESSFUL PROSECUTION
                  OP
         THIS AND KINDRED STUDIES,

              €$n Wnk
      IS RESPECTFULLY INSCRIBED
                  BY
            THE AUTHOR. 
 
         PREFACE
TO  THE  SECOND  EDITION.
   The rapid  sale of the first edition of this work, both in
England and  the United States, proves  its adaptation to the
wants  of the scientific community, and justifies the care and
extra expense with which this second edition has been prepared.
   Although the  first edition  was unusually large, it is not at
all probable that  the demand has been exhausted.  But a little
more than a year  has elapsed since its appearance, yet sufficient
time has been afforded for the author  to  make a  number of
important additions, which increase the value of the work to
the student of nature.
   The facts relating to microscopic science are not the result
of one  man's  labors, or of a  single generation, but have been
gradually accumulating for many years; yet at the present the
number of indefatigable observers is very considerable, and the
author is presumptuous enough to think that  the  preparation
of this manual has increased that number, by  diminishing the
difficulty of the  study, and pointing out the most judicious
methods of observation. 
viii
PREFACE.
  For  the flattering notice taken of this work by the medical
and scientific journals, the author is under many obligations,
many prominent periodicals having spoken of it in terms of the
highest praise.
  It has formed no part of the design of this book to describe
the mechanical arrangements of different instrument-makers)
yet sufficient directions have been given  to enable any one pos-
sessed of a microscope, of any mechanical  form and  arrange-
ment,  to use  it  to  the  best  advantage.  Whatever be the
favorite pursuit of  the  student, whether  Botany, Zoology,
Anatomy, Physiology, or Pathology, the present manual gives
information, by means of which  the microscope may be profit-
ably employed.  In addition to  this, the chapters on Minute
Dissection, Injection, &c, will be of interest to many. 
CONTENTS.
                                                        PAQE
Chapter I.  The History and Importance of Microscopic In-
             vestigation,    .      .      .       .      .13
       II.  The Microscope,     ....       22
       III.  Adjuncts to the Microscope,   .       .      .41
       IV.  How to  Use the Microscope,      .       .       51
       V.  On Mounting and Preserving Objects for Exa-
	MINATION, . . . . .	55
VI.	On Procuring Objects for the Microscope,	67
VII.	Test Objects, . . . . .	110
VIII.	On Dissecting Objects for the Microscope,	118
IX.	The Cell-Doctrine of Physiology,	129
X.	Examination of Morbid Structures, Etc.,	139
XI.	On Minute Injections,	158
XII.	Examination of Urinary Deposits,	169
XIII.	On Polarized Light, .	188
XIV.	Miscellaneous Hints to Microscopists,	196
1 
 
THE  MICROSCOPIST.
                    CHAPTER  I.

 THE HISTORY AND  IMPORTANCE OF  MICROSCOPIC
                   INVESTIGATION.

   From the earliest period of scientific research, the magnify-
 ing 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 minutiae which it displays,
feeling 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 I"
  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  function of the dif-
ferent 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 especially 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 ulti-
mate  structure and composition of the different textures  of
organized bodies.   It  is derived from  !<r<ro<r, a tissue or web,
and Xoyos, a discourse. 
            HISTORICAL  INVESTIGATION.          15

   The attempts made by the early microscopic observers to de-
termine ultimate structure,  were in general  of  little  value,
partly on  account of the imperfections in the instruments em-
ployed, 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  re-
garded 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 struc-
ture.
   Borelli was born in 1608, and lectured as professor in the
University of Pisa in 1656.   In his day a general idea pre-
vailed, that diseases were occasioned by animalculae existing in
the animal  tissues and fluids.  An examination  of abnormal
fluids with the  microscope favored 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 the 
16               THE MICROSCOPIST.
minute  anatomy of the kidneys, spleen, liver, membranes of
the brain, &c, and several of the structures still retain his name.
He also paid attention to the anatomy and transformations of
insects,  the development of the chick in the egg, and the struc-
ture 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 develop-
ment of all organized tissues from cells.
  Lewenhoeck has sometimes been called the father of micro-
graphy.  He 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 improve-
ments 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 contribu-
tions 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 labored 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 ex-
tremely accurate.
  Hewson is  celebrated for  his accurate  observations on the
blood and  lymph corpuscles.  He first demonstrated  that the
blood-globules were flat, 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 re-
sulted.   Optical illusions were mistaken  for  natural  appear-
ances, as was the case with Monro.   In his discoveries respect-
ing the brain  and nerves, he describes them as  being formed
of convoluted fibres, and in his examination of other  textures
ho 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 Jed  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 ele-
mentary 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 ab-
sence of bias in favor  of  certain theories, or strained analogies.
The history of science affords but too many instances of the
baneful influence of  the idola speeds  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 pur-
suits.  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 well-
known names of Ehrenberg, Miiller, Schwann, Schulz, Wagner,
Weber, and Valentin, principally depends on the  discoveries
they have made by means of the microscope.
  In England, 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  Boyal  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 Phila-
delphia College of Medicine, and at other places, were well
attended;  as likewise were his  private  classes.   Of his valu-
able suggestions I have frequently availed myself.
  The advantage of a practical  acquaintance with  the micro-
scope 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 mem-
 branes ? 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 ab-
 scess 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  corpus-
cles, 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 after-
wards  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  Schonlein and Zimmerman in Ger-
 many."
   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- 
HISTORICAL 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 tumors, &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 color of the  hair.  With the micro-
scope, M. 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
length,  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-con-
cave.   D, double concave.  E, a meniscus.
  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 micro-
scopes 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 piano 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 propor-
 tion 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—f ths of an  inch, 15
 diameters—\ inch, 20  diameters—i inch, 40 diameters—gth
 inch, 80 diameters—J^th 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, ac-
 cording  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, d, e, are rivet-
ted.   The middle plate, 6, 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, some-
times carries a mirror, for reflecting the light of a candle or of
the sky through any transparent  object  which may be placed
on the stage.  Into  the  stage  a dissecting knife, h, a pointed
Fig. 2.
instrument, /, 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 
THE  MICROSCOPE.
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.
blood in small fish, while the other two are flat, 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, H,
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  con-
                             3 
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, 6, which is connected to the back-
plate, 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, 7c, highly polished, to the centre
of which, at I, the magnifying glass is adapted.   This is screwed
into the ring i, and  so held that a bright light, as from a can-
dle 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
microscope of Mr.  Slack,  with the improvements of Dr. H.
Goadby, F.L.S., is  the most efficient.   The following is a de-
scription 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 repre-
sented by A, Fig. 5.   The upper surfaces r, r, 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 atttached 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) micro-
scope 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 be-
tween 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. Cod-
dington 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 Stanhope lens, seen at B,


                           Fig. 6.
which is  more easily  made  than the  Coddington lens, but is
inferior to it.  C and D are doublets proposed by Sir John
Herschell;  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.   Wbllaston'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 behind the
Fig. 7.
anterior lens.   The stop was not employed by Dr. Wollaston
as his lenses were of such high power that they nearly touched 
THE  MICROSCOPE.
31
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 dia-
phragm over to the margin of B,  and  those nearest the margin
of A,  pass next the centre of B; and so become  nearly cor-
rected :  the imperfection of one being made to counteract that
of the other.
   An  improvement was made upon this by Mr. Holland, and
is called Holland's Triplet.  It consists of a doublet in  place
of the  first lens,  A, in  the last  figure; retaining the  stop  be-
tween  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 im-
possible 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.
additional lens,  D, is usually added; for  the  purpose of en- 
THE  MICROSCOPE.                33
larging the field of  view.   It is  called the  field-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  color round  the  edge of
the field of view, and also  similar colors around the edges of
the object he is viewing.   These defects arise from the decom-
position  of common white  light;  and are called chromatic
aberration or dispersion.  The  colors 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  refer-
red 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  35° 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 double-
convex  crown  glass lenses, cemented together.   Three  com-
pound lenses  form  the object-glass for a microscope, as repre-
sented 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 color, but
is finally corrected by using the Huygenian 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  dia-
phragm or stop, C.   The  proportions of the  focal lengths of
these lenses should be as 3  to 1, and their distance apart, one-
half 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,
c
   Sometimes, when a very flat 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  ad-
justments 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 diame-
ter,  with a universal joint, and capable of being brought nearer
or farther from the stage, as likewise of reflecting a side-light. 
36
THE  MICROSCOPIST.
  A variety of forms have been given to the mechanism of the
compound  microscope, many  of which are very good,  while
others are exceedingly objectionable.   Suffice it to say respect-
ing 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 conse-
quence.  A microscope body containing the lenses, screwed by
its lower extremity to a horizontal arm, is the worst form con-
ceivable.
  The compound microscope consists of three parts—the opti-
cal part, containing the object-glasses and eye-piece;  the stage
for holding the object; and the illuminating apparatus, which
is either a mirror  below the  stage for transparent objects, or
an illuminating lens  for those which  are  opaque.   Whatever
form may  be given to the mechanical  arrangement,  the parts
alluded to  are found in all, and the principles of their manage-
ment are the same.
  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 repre-
sented in the opposite cut.
  The body slides by a rack and pinion, moved by the milled
head, a, on a strong  dovetailed bar;  and has also a  slow mo-
tion 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,  d, d', d", 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 
 
 
THE  MICROSCOPE.
37
to each other and to the axis of the body, given by the milled-
heads, e, e'; it has also a sliding and revolving plane, /, with
a ledge, g, for resting object-slips upon, and a sliding-picce, h,
with springs for clamping them.   An  upright rod, i, is fixed
on this plane  for  mounting the forceps, v, or for the  spring-
holder, y, when  a glass  trough, u,  is used.   A profile  of  the
glass  trough, with its diagonal plate of glass for conforming an
object, is seen at u'.  At z, is a three-pronged forceps.
  A large double mirror, Jc, concave on one side and plane on
the other, is supported by the  cylindrical  bar, I, and  may be
moved upon it vertically and sideways.
  A movable diaphragm, m, is fixed under the stage for vary-
ing the quantity and  direction of the light when transparent
objects are viewed.   The illuminating lens, n, is used for con-
densing  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 collar, 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 eye-
piece  when its cap is removed.
  The  three Lieberkuhns, o, o',  o",  adapted to the  object-
glasses 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, p, may be slid in its
                             4 
38
THE  MICROSCOPIST.
place, with one of the three dark wells or stops, p, p',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
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 cast-
iron, 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 micro-
scopes used in this country are of French or German manufac-
ture.   Chevalier and Oberhauser  have furnished  some excellent
instruments; but the  mechanism not  allowing  the mirror  to
turn aside from the axis of the instrument, so as to give a side
light, is a serious objection to them, although the optical part
is often very little inferior to the English.
  Dr. Bennet, of Edinburg, highly recommends Oberhauser's
instruments  to  medical men.   He advises the employment of
the No. 3 and  No. 7  object-glasses, answering  to  the £  inch
and 1 inch lens of the  London opticians.
  Hitherto, 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 
THE  MICROSCOPE.                39
procure an achromatic object-glass with shallow magnifiers, not-
withstanding the decided advantage to be derived from their use.
   The microscopes of M. Nachet, and  M. Brunner, of Paris,
have been highly recommended.  Those of the former which I
have seen, are about on a par with the instruments made by
Oberhauser, with the advantage of a larger stage.
   Mr. C. A. Spencer, of Canastota,  New York, has succeeded
in manufacturing object-glasses, which are said to  have an
angle of aperture  even greater than the best English achro-
matics.  With them he succeeded in resolving the fine markings
on the Navicula Spencerii,  since adopted as one of the most
difficult test objects.
   A  communication  from  Dr. J.  L.  Smith, to Silliman's
Journal, describes the results of an examination of three micro-
scopes by different makers.   From this  it would seem that for
high powers, the  object-glasses of Ross  are the best, Spencer's
rank next, while Nachet's are not much inferior.
   The best  defining object-glass I have yet seen is one I have
made by combining two of Oberhauser's with one of Chevalier's,
so as to make a triple objective.   With this the sets of markings
on the Navicula Angulata are beautifully seen by oblique light.
   Such are the practical difficulties attending the production of
such delicate  instruments,  that there must be  a very  great
difference in the glasses even of the same maker, so that before
purchasing an instrument, it  is always  best to examine  it by
means of some of the test objects hereafter described.

             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. 
40
THE  MICROSCOPIST.
  A, Fig. 11, represents a brass ring, one-thirtieth of an inch
thick,  whose  inner  diameter is about  two-fifths of  an inch.
Having dissolved a  globule  of quicksilver  in  one  part nitric
acid and ten  parts water, he rubbed with it the inner surface
Fig. 11.
  G
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 acces-
sory instruments are  needed by those who would devote atten-
tion to  microscopic researches.  The most necessary or useful
of these we proceed to describe.
  TJie  Diaphragm,  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.
   TJie Condenser.—This  is an arraugement  under the stage
                             ■1* 
42
THE  MICROSCOPIST.
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. Wollas-
ton employed a long tube with a stop between the lens and the
mirror, but Dr. Goring found  it  better  to have the stop be-
tween  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 pass-
ing 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.
                              a
i Wpi	
"^lH	■ 1
is equal to what can be viewed  by the  microscope, and  no
larger.   Below is a sliding tube, b, 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.
   Condensers for oblique illumination.—As the lines on some
test objects require an illumination at a considerable angle from
the axis of the  microscope, various plans have  been suggested
for the purpose.  The most simple mode is  to  turn aside  the 
ADJUNCTS TO THE  MICROSCOPE.        43
 concave mirror from the axis of the instrument, but in this
 way the illumination is confined to one side of the object while
 the other side is  in  shadow.   M.  Nachet has  contrived  an
 oblique prism which can be  revolved  so  as  to throw oblique
 light successively  on  all parts of the object.   Mr. Wenham's
 illuminator consists of a truncated parabolic mirror (somewhat
 the shape of the half of an egg-shell with about half an inch of
 the apex  cut  off)  fastened beneath  the stage  plate.   At  the
 bottom of this mirror  is  a  circular stop of the size of  the
 opening at the other end.  This carries a dark well up nearly
 to the stage plate.   When this illuminator is  used the light
 is thrown  up by means of the plane mirror,  and  by  reflexion
 from the  parabola  is made to  pass behind and around  the dark
 well.  Direct  light is prevented by the  circular disc or stop.
 This is  a most admirable contrivance.   The  objects appear
 brilliantly illuminated on  a  dark  ground.   The illuminator
 usually has a meniscus at the small end  to correct the aber-
 ration of  the slip of glass which carries the object.
   Nobert's  illuminator,  like  the   last,  throws  an  oblique
 light all  round an object,  and of course  there is no shadow.
 It consists simply  of  a  thick plano-convex lens,  in the centre
 of the convex  surface  of  which a deep concavity is made.   The
 plane side is turned towards the object, and  it is placed in a
 manner  similar to the Wollaston Condenser.  The concavity
 in the lens is equivalent to  a dark spot on the convex surface,
 so that a hollow cone of light  is obtained, in the apex of which
 the object  is placed.   It is necessary to have lenses of different
 sizes for object-glasses of different focal lengths.
  Polarizing Apparatus  (Fig. 14), for viewing objects by
polarized  light.  It consists  usually of two  prisms of  calca-
reous 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. 
44                THE  MICROSCOPIST.

                           Fig. U.
   Erector.—This is sometimes supplied with the best instru-
ments.   It consists of a pair of lenses acting like the erecting
eye-piece of the telescope.  It is applied to the draw tube at
the end of the eye-piece towards the object-glass.   It is only
used when it is desired to dissect with  the compound micro-
scope,  as, without it,  the position  of  the object  appears  re-
versed.
   Condensing Lens  and  Lamp.—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.        45
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.
slides  through a socket, working on a hinge-joint.  Sometimes
a  lens of this kind is affixed to the stage of the microscope,
when it  can be used in combination with the bull's-eye lens,
or alone.   C, is  the  object upon  which the light is concen-
trated.  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 a screw.   A shade should always
be used with the lamp, in order to screen the eye as much as
possible from any light save that which  proceeds through the
instrument.   As  it is a  matter 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.   Camphene,  burning-
fluid, and gas give out a very intense  light, but there  is a
tremulous motion in the flame, which is  somewhat unpleasant. 
46
THE  MICROSCOPIST.
  Lieberkuhn, or Silver Cup.—This is a most useful  instru-
ment for viewing opaque objects.   It is attached to the object-
glass 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  struc-
tures.
   It has  hitherto been considered  impracticable to use very
high powers with opaque objects,  but  the Athenaeum 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 £th and Ath 
          ADJUNCTS  TO  THE  MICROSCOPE.        47

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, as in  Wenham's illuminator  for
oblique light; 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 surface, 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. 17.
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.
   Frog-plate;  Fig.  18;  on which frogs or  fish are tied to ex-
amine the circulation of blood in their vessels.  The frog, &c,
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 
48
THE MICROSCOPIST.
four of its toes, and the web is spread out over the large hole
by fastening the ends of the thread through the small holes
in the plate.
                        Fig. 18.
                        o~ o ri
                      O         o

                      •o
                      c         o
                       O        o


                      \J

   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 Tfoths
 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
 it is magnified 500  diameters.   By sketching the object by
means of  the camera, and  then putting in its  place a stage
micrometer, and marking the  divisions over the sketch, they
can again  be subdivided, and so  the  measure  of an object
be accurately taken. 
ADJUNCTS TO THE  MICROSCOPE.
49
  Animalcules, Cage is a round cell with a glass bottom and
top, for confining a drop of water with animalculae.
Fig. 20.
   Watch-Glasses and Fishing Tubes, are useful adjuncts.   The
latter, Fig. 19, are glass tubes of various sizes, by which  when
                              5 
50
THE  MICROSCOPIST.
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 watch-
glass.  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 Compressorium, for applying  pressure to  an  object; a
trough for chara and polypi; a phial-holder, &c.; will also be
found useful. 
CHAPTER  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 satis-
 factorily.  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.
  2.  Delicate observations should not be made when the fluid
which lubricates the cornea of the eye is in a viscid state. 
52
THE  MICROSCOPIST.
  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 ver-
tically.   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  direc-
tion 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 con-
sideration 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
bull's-eye lens  is not  used, the illuminating body should  not
be more than five or  six inches from  the mirror.   The latter 
HOW TO  USE THE MICROSCOPE.        53
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 dia-
phragm, 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 re-
flected 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 substi-
tute.
   " A large proportion of opaque objects are seen perfectly well
(especially by daylight) with  the side-reflector, and  the  dark
box as  a  background; and for showing irregularities of sur-
face, 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."
   The management  of the light with  opaque objects  must
depend in a great degree upon  their size,  and  the manner in
                             5* 
54
THE  MICROSCOPIST.
which they are mounted.  If the object is small, and so mount-
ed 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.
  The transmission  of light obliquely,  as  near as possible at
right angles to the axis of vision, which is recommended in the
foregoing extract, for viewing delicate lines, has a very fine
effect, the field of view being dark, while the objects are bril-
liantly illuminated.   The lines on the most difficult test objects,
as some species of Naviculae, &c, are to be seen in this manner
of illumination, even  when otherwise invisible.   For producing
this  oblique illumination in the best manner, several ingenious
pieces of mechanism have been invented; see page 42.
  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 sufficient
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
                     EXAMINATION.

   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 1£ inches.   The French
opticians, however, prepare  many of their slides  2| inches by
fths 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.
1st, 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. 
56                THE  MICROSCOPIST.
        i
  2dly. In some preservative fluid.
  3dly. In Canada balsam.
  The glass slides should be clear, free from veins and bub-
bles, 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 con-
fervoid vegetable.
  Mr. J.  T. Cooper, some years since, made some experiments
with a view  to determine the best fluid for preserving vegetable
colored 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  confervae.
  One part alcohol to 5 of distilled water, will  preserve even
very delicate colors.  There is, however, the same objection to
the use of this fluid as to the salt and water.  When this is used,
asphaltum cement  may be employed for  securing the  thin glass
cover to the cell.
  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 diffi-
culty  in cementing the thin glass cover upon it.
  A weak solution of chromic acid,—one  part to twenty of 
       mounting  and  preserving  OBJECTS.    57

water—is a good preserving fluid.   It is also recommended for
hardening soft tissues, as the brain, liver, &c, for future dis-
section.  Dr. Vanarsdale, in his introduction to the American
edition of  Hassall's Microscopic Anatomy, speaks highly of it
in this respect.
   One part of naphtha to seven or eight of water is said to be
employed by Messrs. Hett, Topping, and  others, in their in-
jected  preparations.
   One part alum to sixteen of water preserves animal structures
for some time, though bone is injuriously affected by it.
   A saturated solution of  sulphate of zinc is said  to preserve
animal tissues well, with the advantage of hardening cerebral
substance, but it dissolves albumen so as to  cloud the  liquid.
Mr. Straus  Durkhein  says it destroys all parts of caterpillars,
save the teguments, while the perfect insects are well preserved
in it.
   Tulk and Henfrey state that 26 drops of creosote in  a wine-
glassful of distilled water, preserves well, but renders the pre-
parations brown.
   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. 
58
THE  MICROSCOPIST.
  " The A 1 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  de-
composed, 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-
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."
   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 ex-
hibition, 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 fiat 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 
      MOUNTING  AND  PRESERVING OBJECTS.    59

of fluid, which  can  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
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.—White
lead worked with 1 part  linseed oil and: 3 of spirits of turpen-
tine 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 micro-
scopist.
   Holes may be drilled in square pieces of glass,  when a num-
ber of them are cemented together with marine glue, by means
of a copper tube (or drill)  on a  lathe, which is used  with  fine
sand or emery and water.   This form  of cell, as well as the
built-up cell, as it is  called (which is a glass box, the edges of
whose sides are cemented with marine glue), was first contrived
by Dr.  Goadby.
   Pieces of gutta-percha tubes, cemented  on to  the slips by
heat, may  sometimes be used for cells, and answer a good pur-
pose.  Excellent cells may be made by using narrow slips of
glass for the sides, cementing them  with  marine glue.  They
are oblong or square, and are well suited for the larger class of
objects.
   The thin glass cell, which is  made by cutting or drilling a 
60
THE  MICROSCOPIST.
hole in a square piece of thin glass, such as is used for covers,
and cementing it to the slide, will be found of use in mounting
delicate structures.  For the  thicker class of objects the tube
cells, or those built up with strips of glass, are most suitable.

                       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-
tha.  It is  melted  by  heat.   Caustic potash will remove its
traces from glass.   Tulk  and Henfrey give the following recipe
for its preparation:  Dissolve  1 pound of caoutchouc in 4 gal-
lons of coal naphtha; 1 pint of this solution is  mixed with 2
pounds of shell-lac;—it is a most useful preparation for building
up glass cells, &c.   Powdered gum  arabic, made into a mucilage
with distilled vinegar, is said to  be a very powerful cement.  If
greater consistence is required a little calomel may be added.
   Gum Mastich 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.   This was
suggested by Dr.  Goddard.   The  caoutchouc should first be
dissolved in the chloroform, by the application of gentle  heat,
to the consistence of thick mucilage, gum mastich should then
be added until it becomes  sufficiently liquefied. 
       MOUNTING AND PRESERVING  OBJECTS.    61

   A solution of Canada balsam in ether or turpentine, evapo-
rated to such a consistence that it can be laid on with a camel's-
hair pencil, may be used like the last described, as a substitute
for marine glue.
   Lampblack and  white  hard varnish,  when  laid on  imme-
diately, 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  turpen-
tine, will be found very suitable.   Dr. Goadby recommends for
the same  purpose, a mixture  of equal parts  of gold size and
asphaltum dissolved in camphene.   This should be applied in
layers, which should be isolated from each other by coating with
a solution of gum arabic or of marine glue dissolved in white-
wood naphtha.   The object of this isolation is  to prevent  the
cement from  penetrating between the glasses.   Some very
valuable preparations have been ruined from this cause.


               MOUNTING  IN   BALSAM.

   Before  objects  are mounted in Canada balsam  they should
be perfectly clear 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 bal-
sam ; 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.
                             6 
62
THE  MICROSCOPIST.
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
balsam; otherwise numbers of air-bubbles  will be left in the
cells, and the true structure cannot then be made out satisfac-
torily.   The extra degree of heat will expand  the air and
cause it to escape, and the balsam will take its place.
   Some object  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 tra-
cheal 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  over-
heated, show the ramifications of the  trachea, but those which
have been soaked long in turpentine, or have had the air ex-
pelled 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; other-
wise, 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 small table  made of  iron or tin, to which  a spirit-
lamp is applied, as first suggested by  Dr. Goadby;  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
rapidly.
   When animal structures, such as parts  of insects, or injec-
tions, have to be mounted, the heating of the balsam  must be 
      MOUNTING  AND  PRESERVING  OBJECTS.    63

carefully managed, and the balsam itself be very fluid to com-
mence with.   It should be sufficiently warmed to expel all air-
bubbles, and, when  nearly cold, the object should be placed
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 suc-
ceeded in making some excellent preparations at the expense of
but little time  and trouble.   Some operators, after covering
the object with balsam,  if it is one that heat is likely to injure,
as an injected specimen, &c, leave the slide for a day or two, to
allow the air-bubbles to escape before  putting on  the  glass
cover.   But  by careful  management, the plan  above referred
to will serve the purpose more readily.
   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.
   After the slide has been prepared as above, the superfluous
balsam may be removed with  the  point  of a knife previously
warmed in the flame of a spirit-lamp, &c.   The remaining traces
of balsam may be removed by an  old linen rag dipped in tur-
pentine  or sulphuric ether.

         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.
   If the object be too thick to allow the cover to approach the 
64
THE  MICROSCOPIST.
slide, the intervening space may be filled with paper, paste-
board, &c, in which a hole has  been  cut.   Such intervening
substance is very useful  to  prevent pressure upon the object.
If desirable, the name of the specimen, &c, may be written on
this paper, especially if  the cover and slide be equal in size.

          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 sur-
rounded 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.
Fig. 21.
  a, Fig. 21, represents a disc of leather, felt, or other suitable
material, about three-eighths or half an inch in diameter, with a
pin passing through it.  The side for holding the object is to 
      MOUNTING  AND  PRESERVING  OBJECTS.    65

be blackened; the other side is  covered with white paper, on
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
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-
hol) and lampblack,  holding them over  a  candle  to  dry.
Sometimes these cylinders are made 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
recommends  to place the objects on pieces of cork glued to the

                           Fig. 22.
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 must  be the
mounting.   White is, of all colors,  the  worst which can be
employed, unless the object is totally black.
                            6* 
66
THE  MICROSCOPIST.
  MOUNTING  CRYSTALS  FOR  POLARIZED  LIGHT.

  These must be so enclosed  that  the air is  completely ex-
cluded, otherwise a change will take place, and the objects be
spoiled.  When it can conveniently be  done,  it  is  well  to
mount them in  Canada  balsam.  Sir David Brewster recom-
mends mixing cold-drawn  castor oil with the Canada balsam.
In this case the  edges of the  thin  glass cover should be ce-
mented, 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 mounted. 
CHAPTER  VI.
ON PROCURING  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 in-
vestigation.   We shall content ourselves with noticing some of
the most important or attractive in each department.

                       INORGANIC.

   Agate.—This form of silica is often found imperfectly crys-
tallized, and thin plates, prepared by the lapidary's wheel, g^th
of an inch thick, exhibit a rich motley coloring when  viewed
by polarized light.
   Carbonate 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.
   Crystallization 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 quan-
tities of the different solutions  in a little weak gelatine, starch,
mucus, &c   To procure specimens, put a drop or two of water, 
68
THE  MICROSCOPIST.
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  spirit-
lamp 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.   Mix some water with a little charcoal, chalk, &c, in
such a manner that a number of fine particles may be mechani-
cally 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 balsam for pre-
servation.
   Crystals of Iron Pyrites and other substances; Oolites ; and
various sorts oisand; are interesting objects.   The sand  from
Turkey sponge, and from the sea, often contains minute shells
of various kinds,  as the foraminifera, &c, corallines, and  other
zoophytes.     '
   Sections of Granite, 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-Ioduret of Mercury.—The change of color  in this salt
is a beautiful object.  If a  little of it be placed in a watch- 
PROCURING  OBJECTS.
69
 glass, having another inverted over it, and then the lower one
 heated over the flame of a spirit-lamp,  the salt will be  sub-
 limed.  Placed on the stage of a  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 color, which, as they cool, return  to the original red.


                 VEGETABLE TISSUES.

    Vegetable Tissues are prepared by tearing, making thin sec-
 tions, 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 an-
 swer 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 surround-
 ing cellular tissue.  This  process  is  facilitated by  dropping a
 little water on the specimen.   To prevent it moving, the speci-
 men may be fixed with beeswax during  the  dissection.   Ves-
 sels, ducts, and cellular tissue, when prepared, should be kept
 in spirits of wine until mounted.
   Fig. 23 represents  the  tissues in  a longitudinal section of
 Italian Reed;  a,  are  cells of the pith; b, annular ducts; c,
 spiral duct; d, dotted duct; e, woody  fibre; /,  cells of the
integument.
   Cuticles.—The  external covering of plants, or  cuticle, con-
sists of a thin membrane,  adherent to the cellular  tissue be-
neath  it.   Under the microscope it appears traversed  by lines 
70
THE  MICROSCOPIST.
in various  directions, giving its surface a reticulated appear-
ance.   The form  of these  reticulations  varies  in  different

                           Fig. 23.
plants: in  some they are hexagonal, in others prismatic or
irregular.   Cuticles may be mounted dry  or in fluid.  The
geranium, oleander, &c, afford good specimens.  See Fig. 40.
   The cuticle of the under side  of the leaf of many plants,
exhibits  under the microscope  dark spots among their reticu-
lations.  These  are called  stomata,  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 ar-
rangement of the stomata vary  in different plants.
   Cellular  Tissue is the first  and  most generally developed 
PROCURING  OBJECTS.
71
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 colors 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 beauti-
ful object.   The  spiral  vessels diverging from the base,  and
the singular little cellules which fringe the edge, are worthy of
notice.
  Cells differ in form according to the mode in which  they are
aggregated,  a,  Fig.  24,  represents  the  dodecahedral  and

                           Fig. 24.
dotted cells in the pith of elder.  Cells are either surrounded
by a simple membrane, or by thickened walls.   The  thicken-
ing of the wall  takes  place by a  deposit of woody matter on
the inside.  Occasionally, portions of the cell-wall are left un-
 
72                TEK MICROSCOPIST.
covered by deposits, giving rise to porous cells (b, Fig. 24), or
dotted cells (a, Fig. 24); at other times the thickening matter
is in  the form of a ring or spiral coil, constituting annular (c,
Fig. 24) and spiral cells (d, Fig. 24).
   Vascular  Tissue,  prepared  by maceration and  dissection,
presents many interesting subjects.   Spiral vessels, c, Fig. 23,
consist of membranous  tubes with  conical extremities, inter-
nally 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,  b, Fig. 23.  If the pieces
of fibre are still shorter, they are called dotted or  reticulated
vessels, d,  Fig. 23.  The  root of  the garden rhubarb, the
stem of the hyacinth,  the leek, &c, furnish examples.
   A peculiar form of vessel is  met with in the common carrot;
it is obtained from a root in a  layer between the yellow central
portion and the red annulus.
   Sections of Wood.—These  are cut thin, so  as to allow them
to be viewed as transparent objects.   Hard 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 infor-
mation is acquired from them of the real structure of the wood.
For this purpose, if the tree is of the endogenous and branch-
less kind—which grow by additions  to the interior—a vertical
section is also necessary.  If the tree be an exogen, two verti-
cal 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 frequency
and  size of the  medullary rays determine the number  and 
PROCURING  OBJECTS.
73
strength of the branches  of the  tree.   This section also ex-
hibits in coniferous trees (as the pine, &c), the beautiful disc-
like  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 show the
form, size, and connexion of the  woody fibres; spiral,  reticu-
lated, and dotted vessels, &c.; and are far more instructive than
the transverse sections.
   Charcoal.—Thin sections of charred wood are very interest-
ing 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  favorable  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
maybe detected.   In the ashes of coal, a variety of vegetable
structures, as cellular  tissue, spiral  vessels, &c, may  be dis-
covered.  In  these experiments it is necessary  to render the
ashes transparent by immersion in balsam.
   Hairs,  Down, &c,   from leaves  and stems,  are generally
opaque objects.   In the plants which produce cotton, the hairs
                             7 
74
THE  MICROSCOPIST.
are attached to and envelope the  seeds.  Hairs  are composed
of cellular  tissue.   Their functions are said to be either lym-
phatic or secreting.   They offer great varieties in form, some
being stellated, others forked or branching.   The hairs of Vir-
ginian spiderwort (Tradescandia  Virginicd), the sting of the
Nettle (JJrtica  dioica), and  the  radiating scale or  hair  in
Eloeagnus,  the Oleaster, are interesting specimens.
   Pollen may be mounted in Canada balsam;  or, if rather
transparent, in fluid; or dry.   Sometimes the grains are inte-
resting 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
in very diluted  sulphuric acid  opens and disperses the grains.
The  pollen of Datura stramonium,  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.   Some 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 minute,
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 
PROCURING  OBJECTS.               75
iodine capable of acting on them while the membrane enclos-
ing its contents  remains whole.   If the granules be triturated
or immersed 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 mace-
rated 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.   See Fig.  25.   a, represents starch
cells of the pea, showing grains of starch in the interior; b,
separate grains  of  starch,  with  striae and hilum; c, granules
of wheat-starch; d,  sago  meal;  e,  rice-starch;  f potato-
starch ; g, isolated cells of rhubarb, containing starch-granules.
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. 
76                THE  MICROSCOPIST.
  Seeds  are  generally  opaque objects,  and  present  a great
variety of beautiful and interesting forms.
  Hard  Tissues, the  stones and  shells of nuts,  &c,  are pre-
pared like bone, &c, by cutting and grinding.  Some require
the lapidary's wheel.
  Raphides,  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.   Fig. 26, a, represents cells of

                           Fig. 20.
the beet-root, containing conglomerate raphides;  b, octohcdral
and prismatic  crystals  of oxalate  of lime in the cells  of an
onion.  By scraping hickory, or  other bark,  on to a slide,
moistening it with the breath, and blowing off the woody par-
ticles; 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.
  Mosses are supposed  to be destitute of woody fibre and vas-
cular tissue.  When a  leaf is carefully examined,  the  septa 
PROCURING  OBJECTS.
77
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 theca or
seed-vessel, for without it the genera cannot be determined;
while this  part, with the calyptra and operculum, are the most
valuable for the microscope.
   Algae.—Are interesting objects.   The green, mucous, slime-
like 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 algae, and are  often found having zoo-
phytes  adhering to them; they'are  then splendid opaque  ob-
jects.   For mounting in balsam, the smaller kinds, of a bright
scarlet color,  are the most valuable.
   Ferns.—The genera are mainly distinguished by  the posi-
tion and arrangement  of the  organs of reproduction.   These
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  ex-
amples of minute fungi.
   Organic Fabrics possess much interest  in  a commercial
point  of view, in addition  to  the curiosity arising from  the
                            7* 
78
THE  MICROSCOPIST.
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 formed of pure cellular
tissue.  These tubes, from the thinness of  their  sides, often
collapse and  appear  like  flat 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

                            Fig. 27.
wounds.   Fig. 27 exhibits the different  appearance of these
fibres under the microscope; a, fibres of flax; b, cotton fibres;
c, filaments of silk ; d, wool of sheep.
   Circulation in Vegetables.—The circulation in plants, termed
cyclosis, is  a revolution of the fluid contained in each  cellule,
 
PROCURING  OBJECTS.               79
and is distinct from those surrounding it.   It can be observed
in all plants in which the circulating fluid contains particles of
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, ex-
hibit  this phenomenon.   The following  aquatic plants are
generally transparent enough to show the  circulation in every
part of them:—Nitella hyalina, Nitella  translucens,  Chara
vulgaris, and Caulinia fragilis.  In the Frogbit (Hydrocharis),
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  Trandes-
cantia Virginica (Spiderwort);  the delicate hairs on the leaf-
stalk  of  Senecio vulgaris (Groundsel); and a section  of the
leaf of Vallisneria spiralis, will show the circulation, especially
when viewed with a high power.
   For the following recapitulatory list of plants, which  may be
used  in  microscopic examinations,  the  author is indebted to
Balfour's Class Book of Botany, Edinburg, 1852.
   1.  Cells and Cellular Tissue.—Sea-weeds; rice-paper; inde-
pendent cells  with nuclei, in yeast plant  (Torula Cerevisiae);
cells with nuclei and nucleoli in ripe fruit of strawberry, in the
onion bulb, and in ovules or very young seeds; cells united in
a linear series in common mould,  conferva, and  many hairs;
branching  cells  in   many  hairs,   and in some  moulds, as
Botrytis; cells united in fours in pollen of Acacia, and  in some
species of sea-weeds; cells thickened by deposit of lignin, in the
shell  of the Cocoanut, and Attalea funifera or Piacaba palm, in
the stone of the peach,  cherry, and  nut, in the  seed  of the
Ivory palm and Date, in the gritty matter of the Pear; cells
with siliceous covering  in Diatomaceae.  Porous cells in  Elder
pith,  in stem  of common garden Balsam  (Balsamina  horten-
sis), in the outer covering of the seeds of  Gourd and Almond, 
80
THE  MICROSCOPIST.
in the wing of the seed of Lophospermum erubescens, and  in
Calempelis scaber.  Spiral cells  in leaves and stems of many
orchids, as Onicidium and Pleurothallis ruscifolia, in garden
Balsam, in the  leaf of Sphagnum, the fructification of Liver-
worts, the winged seed of Sphenogyne speciosa.  Annular cells
in Opuntia.  Filamentous cells in Mushrooms and Agarics.
Hexagonal  cells  in  pith of Elder.   Stellate  cells in Rush.
Ciliated moving cells in  Vaucheria, Fuci, andChara. Professor
F. Schulze states, that  by means of nitric acid and phosphate
of potash,  the cells of plants, young  or old, hard  or soft, may
be perfectly isolated  for microscopic examination.
   2.  Vessels and Vascular Tissue.—Woody tissue  in the  stem
of ordinary trees; the  fibres may be separated by maceration
from the inner bark of  the Hemp-plant, Flax-plant, New Zea-
land Flax, Mallows,  &c, Disc-bearing woody tissue in Scotch
Fir, Weymouth  Pine, Araucaria,  Altirigia  excelsa,  Cycas,'
Winter's bark tree, Ulicium. Dotted vessels in stem of Willow,
Sugar-cane, Pitcher-plant.  Spiral vessels in Oncidium bicolor,
Banana,  and Plantain;  most liliaceous plants  (as Hyacinth,
Lily, and Crinum), leaf of Geranium and Strawberry, Cabbage,
Lettuce,  Asparagus shoot; branched spirals in Long-leek and
Anagallis. Annular vessels in Opuntia vulgaris, Leek, Equise-
tuml Telmateia.  Reticulated vessels in garden Balsam.   Sca-
lariform  vessels  in  Tree  Ferns, Diplazium seramporense, As-
plenium  pubescens, Osmunda.   Lactiferous vessels in various
species of Ficus, as the India-rubber fig (Ficus  elastica), Gutta-
percha plant (Isonandra Gutta), Euphorbias, Lettuce, Dande-
lion, Celandine,  Goatsbeard.
   3.  Contents of Cells.—Starch-cells  in Potato, angular starch-
granules  in  Rice, compound starch-granules  in  Arrow-root,
peculiar  starch-grains in  the milky juice of Euphorbia.   Air-
cells and lacunae in  the Rush, Sparganium ramosum,  Lim-
nocharis   plumieri,  and  other  aquatic  plants.    Cells  with 
PROCURING  OBJECTS.
81
 raphides of oxalate of lime in Rhubarb root, cells with acicular
 crystals in Hyacinth, cells with octohedral and prismatic crys-
 tals  in Onion and  Squill.  Oil-cells in rind of Orange and
 Lemon, in leaves of Hypericum, and of the Myrtle  order.
 Chlorophyll cells in  Mosses, Vallisneria, Chara;  cells with
 coloring matter in leaf of Rottlera tinctoria, and in petals.


                ANIMAL  TISSUES,  ETC.

   Infusoria.—These  minute animals, some of which are
 only the 2g3outn Part 0I" an incn 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 ani-
 malculae, 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 Rotatoria are herma-
 phrodite, and oviparous.  Many animalculae are loricated;  or
 protected by a shell, or shield, which is generally siliceous:
 others are destitute of such an appendage.
   The following table  exhibits  the  families or  groups into
 which this  interesting department of  animal life has been di-
 vided by Ehrenberg.   Those who  wish  further information re-
 specting them are referred to his work "Die Infusionsthier-
 chen," or to Pritchard's "History of Infusoria, Living and
Fossil."   Dr.  Mantell's work on Animalcules contains also
much valuable information. 
82
THE  MICROSCOPIST.
CLASS  I.   POLYGASTRICA.
   Body
destitute  of
appendages.
(No foot-like
 processes.)
  Gymnica.
      ^ illoricated or shell-less,  Monadina.
1Rlon  "i loricated or shelled,      Cryptomonadina.
plete. (
' self- dividing on all     /
   sides (globular),      j
 self-dividing J1Uoricated.
 unilaterally horicated
   (filiform).  )         '
Vibriona.
Closterina.
 Astasiaea.
 Dinobryina.

 Amoebaea.

• Arcellina.

 Bacillaria.
                Form
               of body
              variable. „
                   f illoricated,......
Foot-like processes             f compound  foot-like  process
     variable     <  ■,  •  (J  J    from one aperture,
   Pseudo-poda.    |  lorlcated> ) simple foot-like process from
                               (   one or from each aperture, ,

      Hairy       I illoricated,.......Cyclinida.
    Epitricha.     } loricated,......Pendmaea.



^hSToV^filloricated,.......Vortjcellina.
only for nutrition, j loricated,......Ophrydina.
    Anopisthia.    (.

Two ditto orifices, f                                          v„„v,0i;<,
    one at each    J illoricated,.......J:«*f*
    extremity.     \ ldricated,......Colepina.
   Enantritena.    \
Orifices situated
    oblique.
   Allotreta.
u
illoricated.
(^ loricated,
•{
mouth furnished with pro- ) Trachelina.
  boscis, tail absent,         )
mouth anterior, tail present,  Ophryocercina.
  ......Aspidiscina.
                               ,  locomotive organs cilii,       Kolpodea.
Orifices abdominal.) illoricated, |      do       do   -various,    Oxytnchina.
     Catotreta.    ) ,„„;„„+„,,   '.!..--    Euplota.
t
loricated,
                         CLASS II.   ROTATORIA.


                     fmarein of  cilii-wreath entire,   j illoricated, Icthydina.
With a  simple con-      °      Holotrocha.           \ loricated,  Oecistina.
 tinuous  wreath of ,, marg;n 0f  cilii-wreath lobed or J i]]oricated) Megalotrochaea.
    C1U1.
(Monotrocha.)
  notched.
Schizotrocha.
\ loricated,  Floscularia.
With a compound
  divided  wreath
        cilii.
    {Sorolrocha.)
     fwi
1 or
 of  {
illoricated, Hydatinea.
loricated,  Euchlanidota.
 with the cilii-wreath divided into
          several series,.
            Pulytrocha.
{ with the cilii-wreath divided intof i]ioriCatea, Philodinaea.
I           two series.            < ioricated,  Brachionaea
            Zygotrocha.           ( 
PROCURING  OBJECTS.
83
  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.
Many remarkable species have been taken in meadow-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  (Sten-
tors and  Vorticellae, 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 mucor, which
on being examined with  the  microscope, proves to be an ex-
tensive  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
mould on the surface  of the earth, has its microscopic inhabi-
tants.
  In  order  to procure animalculae,  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 walking-
cane,  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 
84                THE MICROSCOPIST.
proper depth, or in the neighborhood of water-plants, it should
be  turned  quickly, when animalculae, &c, will  run  into it.
Water-fleas and  Daphniae should be frightened away by shak-
ing the phial before turning.  If in the phial, they go  quickly
to the bottom, and the upper  water  can be poured off.  Exa-
mine  the water  with a pocket lens,  and preserve the  animal-
culae.
  The indications of the presence of infusoria are specks mov-
ing about in the water, or an apparent mouldiness  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 ani-
malcules.
   Small  newts and many larvae should be preserved;  the for-
mer especially,  as they eat up the Daphniae, Monoculi, &c,
that destroy the  Vorticellae.   In the  branchiae 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 bot-
tom 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
the animalculae will be on the surface of the mud, from which
they can be removed with the fishing-tubes (see page 49), 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  card-board, ren-
dered 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  fishing-
tubes. 
PROCURING  OBJECTS.
85
   In order to show the  stomachs, cilia,  &c,  of animalcula?
 under the  microscope, rub some pure sap-green or carmine 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 coloring
 matter may be put into the water on the slide  containing the
 animalculae.  If they be  vorticellae or rotiferae, the particles of
 coloring 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,
 consisting  mostly of Polythalamia, or many-chambered shells,
 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  Infusoria,  such  as those  in guano,
Richmond  earth, &c, require to be well washed and  boiled or
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.  In  guano and Richmond
earth  are  found most beautiful saucer-shaped shells,  having
hexagonal  markings, which have received  the  name  of Cosci-
nodiscus, or sieve-like disc.   They  vary in  size  from T£<jth to
TtfWu °f  an iQCn *n diameter.
  The polishing slate of Bilin, which is found in strata fourteen
                             8 
86               THE MICROSCOPIST.
feet thick, consists almost entirely of the siliceous shells  of
Infusoria, so small that forty thousand millions are contained
in a single cubic inch.
   The eatable earth of Sweden and Lapland is likewise com-
posed mostly of such shells.  A layer of this earth occurs in
the province  of Luneberg, Saxony, which is twenty-eight feet
thick.   It contains a beautiful species of minute, oval, figured
shell called the Campilodiscus.
   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  prepa-
ration, 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 sec-
tions.   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.
   Zoophytes.—Residents at  the sea-side, 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 a fragment of shell  will  be
found,  that  does  not afford a  habitation for  some member
of this interesting family.   The animals  are  generally found
in clusters or compound; sometimes communicating at a com-
mon 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 
PROCURING  OBJECTS.
87
 objects for examination, as there is scarcely a part of the body
 of an insect that does not exhibit some remarkable structure.
   Antennae.—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.
   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 symme-
 trical ridges, canals, dots, &c, giving them, as Reaumer  ob-
 served, the appearance of embossed buttons.   Some are  fur-
 nished with appendages for  peculiar purposes.  Thus the eggs
 of the dung-fly (Scatophaga putris) has two oblique 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
 cinered) are furnished with  a coronet of spines, forming a re-
 ceptacle  for the egg  which is  deposited immediately after-
 wards.   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 gnaw or  burst through it.  The color
 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 masse.   Some arrange them symme-
 trically, and others  enclose them  in a mass of gluten, espe-
 cially those whose larvae inhabit the water.  Many species  em-
ploy  a gummy matter to attach them firmly to the substances
on which they are placed; while some,  as the yellow-tail moth
(Arctia chrysorrhaea),  wrap  them in a coating of  down, which 
88
THE  MICROSCOPIST.
they pull off their own bodies;  and the lackey moth  (Lasio-
campa Neustria), deposits  her eggs in a spiral coil round  the
stems 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  en-
graved and colored, and form the  most brilliant of all opaque
objects.   Some are  covered with  beautiful iridescent  scales,
and others are furnished 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 splendor  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, Arachnida, &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. 
PROCURING  OBJECTS.
89
   The external form of the eye may be  seen in situ in all in-
 sects 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.
   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 colors.
   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 sup-
 port themselves on  polished surfaces, and against the  force of
 gravity, is very remarkable, and it is doubtful if it be  yet per-
 fectly 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.
   Hairs of Insects, &c, may  be mounted  dry, in fluid, or in
 balsam.   In  some spiders the  hairs are branched; in the larvae
 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 in-
sects will be  further treated of in  the chapter on Test  Objects.
                             8* 
90
THE  MICROSCOPIST.
  Heads, Mouths, &c.—The manducatory apparatus of insects
is a subject of great interest to the entomologist.   The  divi-
sion of insects into  Mandibulata and  Haustellata are  founded
thereon; the first having jaws, the latter a proboscis or suck-
ing instrument.   Some of them require  but little preparation,
and may be  mounted  as  opaque  objects; others, as the pro-
bosces and lancets of flies and bees, demand considerable skill
to display them to the best advantage.   When thin and trans-
parent, 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.
   Parasitic  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 Cynips quercus, 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 colors  may be selected.
   Among the Acari,  may be mentioned  the cheese-mite,  A.
domesticus,  and the itch-insect,  A.   scabiei.  To  obtain the
latter, the operator must examine  carefully the parts surround-
ing each pustule, and  he will generally  find in the early  stage 
PROCURING  OBJECTS.
91
 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  de-
 tect its haunts.
   To obtain the Entozoon folliculorum, which is a parasite
 occurring in the sebaceous follicles of the skin of the forehead,
 nose, &c, squeeze  the neighborhood of the little black spot
 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 from 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.  au-
 tumnalis,  is a very painful  source  of  irritation  to the skin
 wherein they may have insinuated themselves.  They may be
 dislodged with a needle, and mounted in fluid or balsam.
   Trachea? and Spiracles of Insects.—The respiratory system
 of insects  will be described  in the chapter on Dissections, to-
 gether with their nervous, digestive, and circulatory systems.
 The manner of mounting them has been described.
   Stings,  Ovipositors, &c, frequently require considerable care
 in dissection.   They may be mounted in fluid or balsam.  In
 order to prepare them, the abdomen  should be laid open by a
 slit along the back  of the insect,  in  order to obtain a view of
 the relations of the  various parts; then the  posterior segment
 should be fixed to a loaded cork under water and dissected  be-
 neath a  shallow magnifier.   The  dissection should  be  made
 from right to left, proceeding from without towards  the interior,
 as far as the median line, when  it should be continued from
within outwards.  This mode of dissection may also be advan-
tageously employed  to display or procure other objects of inte-
rest.  See  the chapter on Dissecting Objects.
   Shells  of  Mollusca.—The  structure of  shell  has only 
92
THE  MICROSCOPIST.
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 experi-
ments  of  the latter gentleman, undertaken at the request and
expense  of the  British Association, the calcareous matter in
all shells is nearly equally crystaline in its aggregation, and
the particular forms which  their fracture  presents are deter-
mined chiefly, though not entirely, by the arrangement of  the
animal basis of the shell, which possesses a more or less highly-
jorganized structure.
   All  thin  sections of recent  shell are  translucent,  except
when  the coloring matter is  opaque, or when the calcareous
matter is deposited in a chalky state between the  true laminae
of the  shell, as in the oyster.
   Dr.  Carpenter  classifies  shells, into—1. Prismatic cellular
structure, as exemplified in the Pinnas.   2. Membranous shell
substance, as the My a, Anatina, and  Thracia.   3. Nacreous
or pearl structure, as the inner surface of some species of Ostrea
and Mytilus.  4.  Tubular structure, as the outer layer of Ano-
mia Epliippium,  Lima scabra,  &c.  In some  cases the tubes
run at a distance  from each other obliquely through the shell,
as in Area N003.   5. Cancellated structure.   Examples of this
latter  division, which somewhat  resemble the cancelli of bone,
are only met with in certain fossil shells.
   Shell should be examined microscopically in three ways : by
reflected, transmitted, and polarized light.   For the first, frag-
ments 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 of Fish.—M. Agassiz has  arranged  the  class of
fishes  into four  orders,  according  to  the  structure of their
covering, as follows: 
PROCURING  OBJECTS.
93
                     Enamelled Scales.
  1. Placoidians.   Cartilaginous fishes, having prickly or flat-
tened spines, as the skates, dog-fish, and sharks.
  2. Gano'idians.   With 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 Enamelled.
  3.  Ctenoidians.   Scales notched or serrated on their posterior
free edges, as the perch.
  4. Cycloid fishes, with smooth scales, more  or less circular,
and laminated, as the herring, salmon, &c.
  Among the  various kinds of fish-scales  selected for micro-
scopic objects, those of the eel  are  much prized, as it was for-
merly considered that it had no scales.  They may be obtained
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, etc.—Hairs are composed of an aggre-
gation of epithelium cells, and the color  depends upon  the
quantity of pigment deposited in or about each cell.  They may
therefore be called elongated developments of the epidermis.   A
transverse  section is  not always round, but  may be oval, flat-
tened, or reniform.   Henle has shown that the curling  of hair
depends  upon  its  form,  and that  the flatter the  hair  the
more  it curls,  the  flat side being  directed towards the curve
described.   P. A. Browne, Esq., of Philadelphia, has attempted
to show a specific difference in the races of men from the shape
of the transverse sections of their hair, but we think without
success.  It is not  likely that scientific investigation will ever 
94
THE  MICROSCOPIST.
.overthrow the assertion of Scripture,  "God hath made of one
 blood all nations of men."
   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  termed 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 color, 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 same 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
 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 endos-
 mose.  Their appearance varies  as  they are viewed a little in
 or out of the focus of  the microscope; in one  place showing a 
PROCURING  OBJECTS.
95
nucleus or spot in the centre,  and in the other a thickened
edge, like a ring (a, Fig. 28).   In all air-breathing, oviparous,
vertebrated animals,  the blood-corpuscles are  oval, and a nu-
cleus 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 Siren  acertina, b, Fig.  28,  show that the nucleus consists
of a cluster of nucleoli enclosed in a  capsule in the centre of
the oval blood-disc.  The  length of the disc  in  the  Siren is
?^th of  an  inch,  while the diameter  of human blood-discs
average ^no^b. of an inch.

                           Fig.  28.
   Very frequently, under the microscope, the blood-corpuscles
unite by  their flat surfaces, so as to form rows, like  piles of
coin; the disposition to which is proportionate to the quantity
of fibrin in the blood.
   When the corpuscles are observed in a drop of blood spread
out between two plates of thin glass, they will often be seen to
present a  tuberculated or mulberry appearance, which is sup-
posed by Donne to depend upon commencing desiccation, and to
arise  from deficiency of serum.   Others ascribe it to evapora-
tion from the edge of the slide.   In many of my own observa- 
96
THE  MICROSCOPIST.
tions the globules presented a compound appearance, consisting
of several granules, one in the centre, with the others disposed
around it; the regularity of which appearance seems to intimate
its connexion with the structure of the corpuscle.
   Circulation of Blood may be seen in the web of a frog's foot
(see page 47); in the fin or tail of a fish; and in the legs, &c,
of many spiders and insects,  especially aquatic larvae.  There
is nothing so wonderful and pleasing as the sight of the blood-
corpuscle coursing through the vessels in the web of a frog's foot,
when seen  with a power of about  200  diameters.  The re-
searches of Kaltenbrunner,  a distinguished German patholo-
gist, on the circulation of blood in a frog's  foot, and the influence
of various irritants upon it, as seen under the microscopejv have
added  much to our knowledge respecting congestion and  in-
flammation, 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.
  Hassal remarks, that the circulation of blood is seen  to the
greatest advantage in the tongue of a frog.   For this purpose the
frog should  be secured by a bandage to a thin flat piece of cork,
&c, which is perforated at one extremity by a square aperture.  To
this aperture the mouth of the frog should be secured, and the
soft, pulp-like tongue being drawn out by a pair of forceps, and
spread out over the aperture, may be retained in position by pins.
The piece of cork (answering instead of the frog-plate) should
then be fastened to the stage of the microscope.
  In  the view of this structure, we have displayed in  action
various parts of the animal organization; arteries, veins, nerves,
muscular tissue,  epithelial cells, and glands.   \_Microscopic Ana-
tomy.']
  Bone should be cut into thin sections, about g^th of an inch
in thickness.  They can  be cut  with a fine saw,  such  as are 
                 PROCURING OBJECTS.               97

made of watch-spring.  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 made.
  The sections may be cleaned from grease by soaking in sul-
phuric ether.
  The bloodvessels of bone when  injected are  rendered more
conspicuous if the  earthy parts of the bone are  removed by
means of an acid.   They may then be kept in oil of turpentine,
which renders the tissue more transparent.

                           Fig. 29.
  When animal tissues are consolidated by the deposition of
earthy matter within  their cells  and fibres, a hard, solid sub-
stance 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
                             9 
98
THE  MICROSCOPIST.
 does not occur in  all the cells, as the bone requires to grow
 and be nourished;  hence arises its  peculiarity of structure.
 Independently of its hollows, or  cancelli, the hard part of
 the bone is .traversed by canals,  called Haversian,  which  run
 in  the direction of the laminae ;  these are connected by trans-
 verse communications.  In a  thin  transverse section of  bone,
 the solid matter may be observed arranged around  the Haver-
' sian canals in concentric rows (Fig. 29).   Among  these layers
 dark specks are dispersed. These dark specks (called  lacunae,
 or corpuscles of Purkinje), when magnified about 200 diameters,
 are observed  to be  cavities  of an  irregular, oval  form, from
 which emanate numerous minute  branch canals.   These cavi-
 ties appear dark for the  same reason as  a  minute  air-bubble
 does in  Canada balsam,—namely, the difference of refraction
 of  the two media.   By means of  these branches (canaliculi),
 lacunae,  and  Haversian  canals,  the bone  is nourished with
 proper fluids.
   It has been shown  by Mr.  J.  Quekett,  that  there are diffe-
 rences in the  form and size of the lacunae, in the various classes
 of animals, sufficiently characteristic to allow of the assignment
 of  minute fragments of bone, with the aid of the  microscope,
 to their proper class.  The lacunae of reptiles are distinguish-
 able by their  large size, and long oval form; and those of fish,
 by their angular form and the fewness of their radiating cana-
 liculi.  The  lacunae of the  bird may be distinguished from
 those of the mammal, 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 lacunae in the  four classes
 of  vertebrata, bear  a close relation to the sizes of their blood-
 corpuscles.
   Sections of 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 
procuring  objects.
99
matter.  These should  be mounted in fluid, the others dry, or
in balsam.
   A tooth consists of three distinct structures, the relative pro-
portions and arrangement of which constitute the chief differ-
ences in the teeth of various  animals.   1.  Enamel.   This is
crystallized phosphate of lime, deposited in the form of long
prisms each about 3 (/^^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 struc-
tures  of the tooth.  This is especially the case with the grind-
ing teeth of large herbivorous  animals.   2. Dentine, or Ivory.
This forms the principal substance of which the teeth are com-
posed.  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 coloring matter by soaking the tooth in a solution
of Saunder's wood, &c.  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.   3.  The bone  or  Cementum, 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,  ex-
hibiting 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 trans-
verse  sections should be made.
   Skin.—The  skin 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 
100
THE  MICROSCOPIST.
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 papillae.  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 the hairs and the hair follicles.   The skin may be ren-
dered firm enough for  vertical section by hardening in a satu-
rated solution of carbonate of potash or in strong nitric acid.
   The epidermis may be separated by maceration  in water, or
by plunging the  skin into water nearly boiling  hot.   Great
care must be taken  in  separating it  in order to see the coecal
prolongations sent by  it to line the sebaceous crypts, bulbs of
the hairs, &c.
   The capillary network of the cutis  vera may be seen  in in-
jected 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
colored layer, which consists of a series of minute  hexagonal
cells, containing pigment.  The same structure may be seen
in the skins of animals whose 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 inject-
ed;  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 open-
ings of the sudoriferous glands, can be well seen.
   The two layers of integument in insects, &c, may be sepa- 
PROCURING OBJECTS.
101
rated mechanically, or by maceration in  dilute hydrochloric
acid.
   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
laminae, 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 may 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 humor added,  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.
   For the dissection of the eye, the plaster mould, described in
the chapter on Dissecting Objects, will be  found useful.  The
eye may be fixed  to the plaster  by  bent pins while it is yet
fluid,  as otherwise  it would not remain firm.   Sometimes the
eye is frozen, to facilitate dissection.
   Muscular Fibre.—Muscles  are of two kinds,  voluntary
and involuntary; from their functions.   The voluntary muscles
of all  the vertebrata, and  the articulate animals  (as insects,
                           9* 
102
THE  MICROSCOPIST.
&c), have their fibres marked with transverse striae.   The in-
voluntary muscles are not so marked.   These marks are sup-
posed to point out the ultimate corpuscles  or cells of which
the fibrillae 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.   Others
have thought the  transverae striae  to be due to a corrugation
of the fibre.  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 lon-
gitudinal arrangement of cells.  Perhaps the true structure is
a compound of both these modes;  the sheath being spiral, and
the ultimate  fibre longitudinal.  If we should state that the
ultimate granules or cells of muscular  substance  are arranged
in fibres, and that a number of such fibrillae are enclosed in a
spirally corrugated sheath,  a number of such bundles being
united together;  the description would  correspond  with the
majority of observations.
   A small portion of muscle, freed from cellular tissue, may
be put on a slide with some kind of fluid, placed under the dis-
secting 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  compressorium.  The capillary blood-
vessels may be seen when injected.  By the use  of the com-
pressor, the  thin  recti muscles of the eyes of small birds, 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 
PROCURING  OBJECTS.
103
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
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.  Dr.
Stilling recommends to place the spinal cord in weak  spirit for
twenty-four hours, after  which  it may be successfully steeped
in stronger spirit,  before sections are made.   He directs the
sections to be made with a razor whose surface  is moistened
with alcohol.
  Fibrous and Areolar Tissue.—Nearly allied to involun-
tary 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 color, 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 ligamen-
tum nuchae of the necks of some animals, especially of the
ruminating tribe;  it also enters largely into the  formation 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 color.
They may  be prepared as muscle  or nerve, with the needle
points.
  Cartilage.—Consists of  cells, contained in cavities which
are  formed  in  a  solid  and hyaline intercellular  substance.
(Fig. 41).  In fibro-cartilage, instead of homogeneous intercel-
lular substance we meet  with elastic  fibres.  The structure is
easily examined by making thin sections. 
104
THE  MICROSCOPIST.
   If any of the above tissues are to be kept, they should be
 mounted in fluid, as spirit and water, or the creasote liquid.
   Mucous and  Serous Membrane.—Mucous membrane is
 the investment of all the internal parts of the body, continu-
 ous  with the skin.  Every cavity,  organ,  or  gland, which
 opens on the surface, is lined by it.  Shut  sacs are lined by
 serous membrane.
   These  membranes 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 papillae.
   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,
 &c,  is made up of it.   Detached scales may be obtained from
 the inner side of the mouth or by  scraping any of the serous
 membranes gently with  a knife.   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 flat, 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
intestine.   It is supported upon a submucous areolar tissue, in 
PROCURING  OBJECTS.
105
 which both the bloodvessels  and nerves ramify, but do not in
 any case enter the membrane itself.
   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 re-
 quired,  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  movable dis-
 secting  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 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 nu-
 merous 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 move-
 ment 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 (branchiae) 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 needle-points 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 from the shell, the movement 
106
THE  MICROSCOPIST.
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.
  Sometimes  the ciliary  movement  may  be  witnessed on
epithelial scales found in the mucus taken from the nasal pas-
sages during a slight catarrh.
  Injected Preparations.—For the mode of making these
preparations, the reader will  refer to the  chapter on Minute
Injections.
  There can be no doubt but that the  blood is, par excellence,
the vital fluid.  From it is derived the material for the develop-
ment of each part of the organization ; nerve as well as muscle,
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
distribution and stimulus.   By them is conveyed  the nutrition
of all the tissues; and through them all foreign substances are
extracted, and the blood  thus rendered  pure and vital.  By
endosmotic  action through their thin coats in the lungs, oxy-
gen  unites with the carbon, and probably the iron  of the blood,
and  carbonic acid gas is expelled; and from their peculiar ar-
rangement  in the kidney, lobules of the  liver, &c, effete mat-
ters  are strained, as it were, from the circulation, and carried
off.
   But there is another function, of equal, if not  superior, im-
portance 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 
PROCURING  OBJECTS.
107
the sensorium, 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 versa.   How other-
wise 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.
  May not the peculiar and delicate arrangements of the capil-
laries in  the different coats of the eye;  the ear;  the papillae
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,
and allowing the blood to flow, the muscles will recover them-
selves."   (Todd  and Bowman.)   We know, too,  that the
stimulus  of too much, or too rapid, blood on the brain, will pro-
duce delirium, and illusions of special sense :—impressions being
made  on  the sensorium independent  of the action  of  usual ex-
ternal stimuli.
  The theory above  referred to, in order to explain or account
for these phenomena, may be expressed as follows :—The prin-
ciple of life, or the capacity for vital action, is a property im-
pressed by the Great Creator upon  the  material  organization
of both animals and vegetables.   In addition to this, the pro-
perties of sensation and volition have been imparted to all ani-
mals.  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 func- 
108
THE  MICROSCOPIST.
tions of volition and  sensation, that the nerves should be sup-
plied with  the proper vital stimulus  of  the  organization—the
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 re-
mark.   They show that the electric fluid could not be suffi-
ciently 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
not of electricity—that if a piece of nerve be  cut out and  be
replaced by an electric conductor, electricity will be transmit-
ted 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.
  More  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.
  Hassall, in his Microscopic  Anatomy, records an instance of
the capillary circulation being maintained for hours in a muti-
lated  portion of a frog's tongue, which had been entirely sepa- 
PROCURING  OBJECTS.
109
 rated  from  the  rest.  A  similar  instance  came  under  the
 author's own observation, in a thin slice from the kidney of a
 mouse, which had been dead for some  hours.   An  account of
 it was published  in the Philadelphia  Medical Examiner  for
 December, 1851, pp. 767-770.
   The frontispiece represents some of  the forms  in which the
 capillaries are  arranged.  Fig. 1, represents the injected  capil-
 laries of muscular tissue, after Gerber,  and a preparation of the
 author's.
   Fig. 2. Injected lobules of adipose tissue, from the  skin of
 a  pigeon: the  lower part  of the figure shows a portion of the
 same, magnified 200 diameters, from Quekett's Histology.
   Fig. 3, is a vertical section  of the  injected  skin of a  dog's
 foot, showing the vessels  of the  sensitive papillae, and of  the
 adipose tissue beneath.   From an injection by Topping, in the
 author's possession.
   Fig. 4, exhibits a small piece of injected mucous membrane,
 from the small intestine of man.   The  villi appear to  lie flat,
 on account of the preparation being mounted in balsam and
 covered with thin glass.   This is one of the  most beautiful of
 the author's preparations.   Not only are the  villi well injected,
 but a conglomeration of flask-like coeca,  or glands, are well seen,
 having the m inute vessels which ramify upon their sides exhibited.
   Fig. 5,  is from a specimen of injected liver, by Topping.
   Fig. 6,  represents the capillary vessels which ramify among
 the air-cells (sections of bronchial tubes ?) in the  human  lung.
   Fig. 7.  Injected papillae of the tongue.
   Fig. 8.  Injected ciliary processes of the eye.
   Fig. 9.  Injected Malpighian bodies from the  kidney.
   Fig.  10.  The  muscular  coat  of the  small  intestine,  from
 Gerber, after Lieberkuhn.
   Figures 11 and 12, represent the most  common modes of termi-
nation of the arteries, either looped or branching—after Gerber.
                             10 
CHAPTER   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 improve-
ments 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 mechani-
cal  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 hav-
ing  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  achromati-
-city 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 illu-
minated by intercepted light, of  which a very  good  example
may be seen in a piece of fine wire sieve,  treated like a dia-
phanous object, also in a thin plate  of metal  perforated by very
small  holes.  The various colors  are  seen according to  the 
TEST  OBJECTS.
Ill
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 spheri-
cal 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 mi-
nute 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.
When 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 colors.
   When an  achromatic combination, perfectly corrected for
both kinds of  aberration, is employed, the globule should ex-
hibit  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 color, except a
general blueness, which results from  the irrationality of the
spectra of the different glasses of which the object-glass is
composed. 
112               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 unsatisfactory
 vision, which is rather increased than ameliorated by augment-
 ing the intensity of the  artificial  illumination;  by an incapa-
 city 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, pro-
 vided  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 bril-
 liant points are very sharp and small.
   In order to explain more fully what is meant by angular
 aperture, let A and a, Figs. 30 and 31, 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  re-
spective  images at I and i, and they will be of equal dimen-
sions.   But if  the  number of rays  proceeding  from A and
falling upon the single lens B, B, is not enough,  when col-
lected 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 repre-
sented  at i,  and the  eye  being powerfully acted on by the
increase of light, will be highly sensible  of it. 
TEST  OBJECTS.
113
  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. 30.                          Fig. 31.
  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 propor-
tions of light, the advantages proposed cannot be derived.
                            10* 
114
THE  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  instru-
ment.
  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 nume-
rous at the base of the hair, and increase towards the apex.
  Mouse 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 color of  the hair
depending on the pigment within the cells.  Under the micro-
scope  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
colored should be preferred.   Like  the  scales on insects, the
hair from different parts of the  same individual varies consi-
derably in structure.
  Hair  of  the  Dermestes.—This very remarkable hair is
obtained from the larva of a small beetle, which preys on dried
animal substances, as bacon and  hams.   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, 
TEST  OBJECTS.
115
 consisting of  several  large  filaments  or spines,  which  are
 pointed at their distal  extremities, and provided with  a pro-
 tuberance 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 ex-
 amination, 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.
   Lepisma Saccharina.—These silvery-scaled insects  frequent
 closets, book-shelves, &c, 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  striae
 appear to  stand out in  bold relief, like  the ribs of a shell.   A
 good glass should show  well the contrast between the striae and
 the interspaces.
   Morpho  Menelaus.—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 striae, giving it a brickwork
 appearance.  If the scale  be flat, which  is  not common, the
 striae should be seen over  the whole surface.   Sometimes the
 scales are damaged, the  pigment having been removed; in such
cases the  cross striae cannot  be seen.   The   pigment,  under
very high  powers,  exhibits a dotted appearance between the
striae.
   Tinea Vestianella, or Clothes Motli.—The scales of these in-
sects are very delicate,  and require  some  tact in the  manage-
ment of the illumination to resolve their lines distinctly.   The
small scales from the under side of the wing  should be taken ;
the others are eas}r. 
116              THE microscopist.
   Pontia Brassica, or Common Cabbage Butterfly.—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
striae are longitudinal,  and  with a power  of 500  diameters
appear to be composed of rows of little squares or beads.
   Podura plumbea, or Lead- Colored Springtail.—The body
and legs of this tiny creature are covered with scales of great
delicacy.  The surface of each, under a power of 500  diameters,
appears covered with numbers  of delicate  wedge-shaped dots
or scales, arranged  so as to form both longitudinal and trans-
verse wavy markings.   A very small scale is a good  test of the
defining power of a one-twelfth or  one-sixteenth  inch  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 striae
are resolved by superior instruments into dots or bead-like pro-
jections from  the surface.   The Navicida  hippocampus,  N.
angulata, N  Spencerii, &c, have been recommended as tests.
A species marked Navicula attenuata, is a good object,  re-
quiring delicate illumination under a high  power, in order to
show the longitudinal striae or  dots.  Several kinds of  Tripoli
may also be used for the purpose.
   For examining the striae on infusorial shells it is often very
necessary to have an oblique  illumination.
   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.
  Artificial Objects.—M. Robert, a Konigsberg optician, 
TEST  OBJECTS.
117
has prepared glass plates, on which are ruled, with a diamond,
systems of a hundred lines, which, 10 by 10, approach' closer to-
gether, according to a certain  standard.  Ordinary instruments
make out the 6th and 7th systems as separate lines.  Superior
instruments reach the 8th and  9th.   No  instrument  has yet
unfolded the 10th system of lines.   This  is certainly  a  great
triumph of art. 
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 vegeta-
ble tissues, yet much has been omitted, which may perhaps be
more fully appreciated under the present head.
   The instruments required in microscopic dissections, or mi-
nute 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 surgi-
cal 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. 32.
blades are kept open by a spring, a, Fig. 32, was much used by
Swammerdam in his dissections.  One of the handles is attached 
DISSECTING  OBJECTS.
119
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.
  The Microtome of M. Straus-Durekheim is constructed on a
similar principle, but more simple in form.   Its appearance is
somewhat like  the common shears, used for shearing  sheep;
the cutting blades being kept apart by their union in the handle,
the distance being regulated by a screw and nut.  By pressing
with the fingers upon  the Microtome it will  close, and open
when they  are removed.  The length of the cutting blades is
ljinch.
   The 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 em-
ployed, but for soft substances, as the liver, spleen, and kid-

                           Fig. 33.
ney, a knife with two parallel blades, called Valentin's Knife,
Fig.  33, may  be used  with advantage.  Dissecting needles
may be  straight or curved.   One of the  latter fixed in a pro-

                           Fig. 34.
per handle, is represented in Fig. 34.   These are very service-
able instruments  for  separating or  tearing  asunder delicate
tissues. 
120               THE MICROSCOPIST.
  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.   Earthenware, or
glass, is the best  material.   One may be prepared with a flat
piece of cork cemented to  the bottom, inside, by marine glue.
  Loaded corlcs are flat pieces of cork with sheet lead cemented
to their under surface with Burgundy pitch, so that they may
readily sink in the water.  To these corks the subject to  be
dissected is fastened with  pins.
  For vermiform animals, long, narrow,  semicylindrical plates
are best; to the convex surface of which  they maybe fastened,
with the legs (if any, as in Myriopoda) hanging along the sides.
  Rests are inclined planes of wood; one on  each side  of the
trough holding the specimen.  If the Dissecting  Microscope,
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 immediately under exa-
mination.
  In addition to  these instruments, a small syringe, camel's-
hair pencil brushes, &c. &c,  will be found useful.
 . For some objects, which are with difficulty kept in place for
dissection, a little plaster may be mixed  to  the consistence of
thin cream, and by means of a brush may be coated over those
parts which are desirable  to  be fixed;  then, by placing it in a
small box or other suitable mould,  the plaster may be  poured
round it, and allowed to  harden.   In this case a loaded cork
is unnecessary, the weight of the plaster being generally suf-
ficient.   The plaster may  be  colored with ink, &c, if its white-
ness is fatiguing to the eye.
  Before dissection, a good light should  be thrown upon the
object by means of the condensing lens (Fig. 15).
  A dissecting microscope is also  generally necessary.  This
may be one specially designed for the purpose, as Fig. 5; or the 
DISSECTING OBJECTS.
121
compound microscope with an erector, page 44; or a lens 2 or
3 inches focal length, or even smaller, fastened to a stem, so as
to be adjustable over the object.
   The following account of Swammerdam's  dissections com-
mends itself  to  all microscopists.  It is condensed from an
extract in Adams's Essays, from Boerhaave's Life  of Swam-
merdam.
   In the preparation of objects, no man was ever more  suc-
cessful or more  indefatigable  than  Swammerdam.   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.
   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,  distinguish,  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-
thing that appeared without further dissection,  he  then  pro-
ceeded to extract the viscera in a very cautious and leisurely
manner; first taking care to wash away  and separate,  with
                             11 
122
THE  MICROSCOPIST.
fine  pencils,  the fat with  which insects are plentifully sup-
plied.
  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 tracheae, which  by this means  he could
separate from  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 them 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.
  He discovered that the fat of all insects  was perfectly solu-
ble 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 deserves 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
them, with very little trouble, from the exuviae, or skins,  with-
out any danger  to the parts;  so that by this contrivance  the 
DISSECTING  OBJECTS.             123
 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 labor
 and  unremitting  ardor in  these  pursuits,  or his  wonder-
 ful 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  All-
 perfect 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.
   In addition to the chapter on procuring objects, a few further
 remarks on the internal anatomy  of insects  will not be out of
 place.  For the microscopic anatomy of other parts of the  ani-
 mal organization, the reader is referred to Chapter V.
   1.  TracJieae, or Respiratory System of Insects.—Respiration
 in insects  is effected  by means  of two great longitudinal  ves-
 sels or canals called tracheae, 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 pre-
 vent the admission of  foreign particles.  The  tracheae emit an
 infinite  number of  ramifications, extending to  all parts of the
 body, so that air circulates freely  in every part.  The  tracheae
 consist  of an  elastic  spiral  cartilage rolled up  into  a  tube,
 lined on each side with cellular tissue.  In Fig. 35 the tracheae
 of the larva of  the Cossus ligniperda, or  willow moth, is re-
 presented.   Along each side of  the caterpillar are seen  the
 spiracles.
  To obtain the tracheae, &c, the insect should be placed in  a
small trough with water, and be securely fixed to a loaded cork.
The body being laid open, next to  the  large viscera, the  tra- 
124
THE  MICROSCOPIST.
chese will become visible.  These  vessels, naturally filled with
air, are of a beautiful metallic white color, which produces a
very pretty effect upon the darker grounds of the other organs
upon which  they run.   The stomach and intestinal  canal, if
large and transparent, will exhibit the minute ramifications of

                           Fig. 35.
the tracheae 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 very little dissection.   They 
DISSECTING OBJECTS.
125
may be cut from the body with a scalpel or pair of scissors, and
be mounted in fluid or in balsam.
  2. The Digestive System consists of the pharynx; the oeso-
phagus, or gullet; the craw, or crop;  the gizzard,  or ventri-
culus;  the  stomach, or duodenum;  the intestines; and  a
number of  slender  membranous  tubes, filled with  a  fluid
analogous to bile.  In  addition to  these,  the  salivary glands
may be mentioned.
  There is a 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. 36.
is long.  There are also differences of structure which clearly
show the adaptation of means to ends.  A, Fig. 36, is the
                            11* 
126
THE  MICROSCOPIST.
digestive system of Melolontha.  B, is that of Blatta Ameri-
cana (American Cockroach), a is the oesophagus, 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 d, 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.   They may be  prepared by making a longitu-
dinal incision and spreading out to dry; or by inflating, after
the gizzard has been cleaned  of its contents,  by means  of a
small syringe.  After drying in the latter mode it may be cut
in two, so as to show  the parts in their natural position.
   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.  37 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
oesophagus 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 exception 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.  The Circulatory System is  placed along the  back,  and
consists of a heart or dorsal vessel; which  is  a tube divided 
DISSECTING  OBJECTS.             127
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 a Limulus (king crab), Dr. Goadby traced the artery
into certain large sacs or vessels, evidently answering the pur-
pose of veins (venous sinuses).  It is probable the same holds

         Fig. 37.                        Fig. 38.
good of insects.  Fig. 38  represents the  dorsal  vessel in the
larva of Ephemera.   The  arrows  indicate the current of the
fluid.
 
128
THE  MICROSCOPIST.
  In dissecting the heart or dorsal vessel,  the body  must be
opened from the ventral surface, all the viscera removed, and
the vessel left with its ligaments attached to the upper rings of
the body.   Or  the  superior segments of the body may be re-
moved by cutting with scissors along the lateral membranous
bands and removing all the upper part of the abdomen.   The
dorsal vessel may then be slit  open.   This  dissection requires
much care and great steadiness of hand.
  5. The muscular system of insects is very extensive.   Lyonet
dissected and described 4061 in the caterpillar of the goat moth
(Cossus  ligniperda).  M. Straus-Durekheim and others recom-
mend that the insect should be cut in two  a  little to the right
or left of the median line, so that the half to be examined shall
be a little larger than the other, that the azygos muscles, &c,
in the centre be not injured.  Beginning then with the internal
profile, layer after layer of muscles should be dissected.
  By previous maceration in dilute  alcohol  the  muscles are
slightly hardened.  If left too long, however, they will become
detached from the integument. 
CHAPTER  IX.
      THE  CELL-DOCTRINE  OF  PHYSIOLOGY.


   Reference has already been made at page 107 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 con-
founded  it  with  the  entity,  or being, in the  animal, which
perceives 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 rea-
sonable 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
of instruction.  Chemistry teaches us that the ultimate elements 
130
THE  MICROSCOPIST.
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 ele-
ments, 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
compounds, 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 compounds.   Such are urea, uric acid, pepsine, sugar
of milk, &c.
   Hitherto, no one has succeeded in producing the true proxi-
mate  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 Wohler.
   " 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. 39.
   " This appears, from the  interesting researches of Schleiden
and Schwann, to be the primary form  which organic matter
takes  when  it  passes from  the condition  of a proximate 
       THE  CELL-DOCTRINE OF PHYSIOLOGY.    131

principle to that of an organized structure."  (Todd and Bow-
man.)
  There are some animal tissues, however, which seem to have
a lower  grade  of organization  than cells, being apparently
Fig. 39.
produced by the simple solidification of the plastic or organiza-
ble fluid:  this fluid is, however, prepared by cells, and is set
free by their rupture.  This seems to be the case with the  deli-
cate membrane known as the Basement or Primary Membrane,
beneath the epidermis or epith^ium.  According to Dr.  Car-
penter, in many specimens- of this membrane, no vestige of cell-
structure can be seen, and it resembles that of which the walls
of the cell are themselves constituted.  In other cases it pre-
sents  a granular appearance under the microscope, and is  then
supposed  by  Henle 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 blastema, 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  xutost, a vesicle, and  (3\*sog, a germ), or
cell-germ.  From  the side of this nucleus a thin transparent
membrane projects,  like  a watch  crystal from  the  dial, and 
132
THE  MICROSCOPIST.
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 ger-
minal cell.   The fluid in which the granules  are first deposited
is ealled the cytoblastema.
  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 nu-
triment, 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 dis-
eased secretions, as  pus.   In the  inflammatory  process they
are produced in great quantities; and  the  malignant growths,
such as cancer and fungus hcematodes, 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 (see Fig. 24); some being sphe-
roidal,   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, 
       THE CELL-DOCTRINE OF PHYSIOLOGY.    133

  At other times the cells are elongated and  fusiform, as  in
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 bounda-
ries 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 Gera-
Fig. 40.
nium-petal, Fig. 40;  this seems also  to  be the case with the
nuclei of the bone cells.  In vegetables,  the wall of the  cell
always remains, while in bone it disappears, and the canaliculi
anastomose.  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 aggre-
gation of granules;  in this manner, the dental  tubuli appear
                             12 
134
THE  MICROSCOPIST.
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.
  " 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  pro-
duces 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 labor;
so that, by the concurrent labors  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 " Physiolo-
gical x\natomy and Physiology  of Man."
  " 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 ovum or egg.
It is of that form which, in a former page (see  Fig. 39,  page
131), 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,  con-
sisting 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, 
        THE  CELL-DOCTRINE OF PHYSIOLOGY.    135

 or the germinal vesicle of  the egg, is the nucleus of the  first;
 and the  third, which is called by embryologists the germinal
 spot, is a nucleolus to  the  second.   It  appears  from the  re-
 searches 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 develop-
 ment of new cells,  for the  formation of the embryo.
   " 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 subdivi-
 sion of the nucleus into two or more segments, and  the forma-
 tion 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  take
 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. 41 exhibits  a section of one of
 the branchial  cartilages  of the  young tadpole.   Within  the
large parent-cells, that are held together  by intercellular  sub-
stance, a, b, c, we observe secondary cells in various  stages of
development:  at  (/, 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 li, two such nuclei are enclosed within 
136              THE MICROSCOPIST.
a common cell-membrane;  at i, we see three new cells (one of
them elongated, and probably  about to  subdivide) within the
parent; and in each of the two groups at the top and  bottom
of the figure, we have four cells, separated by partitions of in-
tercellular  substance, but having manifestly originated from
one parent  cell.
  Fig. 42 represents endogenous cell-growth in cells of a me-
liceritous tumor; 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 from the
granules of the nucleus.
  The following arrangement of animal tissues is based upon
that adopted by Dr. Carpenter.
  1. Simple membrane;  homogeneous, or nearly  so, employed
alone, or in the formation of compound membranes.  Its prin-
cipal  character in  extension, but its ultimate  structure  de-
fies the highest powers of the microscope.—Examples are seen 
       THE  CELL-DOCTRINE  OF  PHYSIOLOGY.   137

in the posterior layer of the cornea, capsule of the lens, sarco-
lemma of muscle, &c.
  2. Simple  fibrous tissues, including the white and yellow
fibrous tissues, and the  areolar tissue, which is formed from
them.  Henle 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.
                           12* 
138
THE  MICROSCOPIST.
   6.  Simple  isolated  cells,  forming  solid  tissues  by  their
aggregation;  as fat cells, the vesicles  of gray nervous matter,
absorbed cells of the villi, and the cellular parenchyma of the
spleen.   In these cases the cells are held together by the blood-
vessels and areolar tissue, which pass in between them; in car-
tilage, and other tissues allied to it in structure, the  cells are
united by intercellular substance, either homogeneous, or of a
fibrous character.
   7.  Sclerous or  hard tissues,  in which the cells have  been
more or less consolidated by internal deposit, and more or less
completely coalesced with each other; as  the hair, nails, &c.
These instances may be more properly ranked under the epi-
dermic tissues; the result of consolidated deposit is more cha-
racteristically seen in bones and teeth.
   8.  Tubular tissues;  formed by the coalescence of the cavi-
ties 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.
  EXAMINATION  OF  MORBID  STRUCTURES,  ETC.

   For the purpose of making a microscopic analysis of abnor-
mal or other fluids, certain chemicals will be required; as liquor
potassae, ammonia, ether, and alcohol, acetic, nitric, hydrochloric
and sulphuric acids; together with a few test-tubes 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 49)
will be of service for this purpose.
   If there be sediment in the fluid, it should be allowed to sub-
side, when  it can be transferred by the  fishing-tube  to  the
slide.  A small  quantity  of any reagent  which may  be de-
sired, 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
each other so nearly in many of their characters, it becomes of
importance to have some test whereby they may be distinguished 
140
THE  MICROSCOPIST.
 from  each  other.   The  fluid  employed for  this purpose  is
 acetic acid.   When  this is  added to a fluid where pus is  pre-
 sent, 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 nu-
 clei, 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 membran-
 ous cell-wall untouched.
   Earthy matters require the aid of  the  acids for their solu-
 tion ;  these should be added in a dilute form, so that their sol-
 vent action may  be more easily witnessed.
   Solid parts, as tumors,  &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 needle-
 points*.  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 re-
 moval from the  body, as changes, of form  in  the softer sub-
 stances speedily take place;  but if  some  time  has  elapsed,  the
 part from which the sections are  taken should be at some dis-
tance  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
Mr. Quckett, to  whose book we have already been much in-
debted during the progress of this work. 
              MORBID  STRUCTURES, ETC.          141

   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 con-
 tamination.   It was even thought that cancers  could thus be
 distinguished from scrofula  and all other more innocent dis-
 eases; while, at the same time, we could form a  conclusive
 opinion as to the propriety  of attempting or  declining a sur-
 gical 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 con-
 nected 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 McClellan, we may be
 permitted to remark, that notwithstanding much has  been done
 by the labors of European and other observers, minute patho-
 logical 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 in-
 vestigations, although we  think he places  too little value upon
 them.   He says, " Chemical  analyses  and microscopic re-
 searches  have  lately proved  that a great number of cases (of
 tumors)  which  were once thought to  be  scirrhous,  or cartila-
 ginous, or osteo-sarcomatous,  are really composed.of  condensed
 fibrine of the blood, sometimes partially altered  into albumen
 or gelatin."
  The microscopic appearance of a fibrous tumor is  exhibited
in Fig. 43 (after Vogel).  It shows interlacing fibres, C.  Pri- 
142
THE  MICROSCOPIST.
mary cells with nuclei  and nucleoli, A, and the same cells
elongated  and becoming caudate, B.   The  interlacing fibres
appear to be identical with the fibres of coagulated lymph.

                          Fig. 43.
   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 tubercles, 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. 44 shows the
microscopic appearance of typhous matter from the mesenteric
glands.   A, an  amorphous,  slightly granular  mass,  of a
brownish-white color,  with an immense number of cells depo-
sited ; B, the amorphous mass treated with acetic acid, by which 
MORBID STRUCTURES,  ETC.          143
it was rendered transparent, and gradually dissolved, upon which
many minute cells with  a  sharp outline came into  view, being
unaffected by the acid (Vogel).
Fig. 44.
  There seems no distinction between tuberculous matter and
that of scrofula or typhus.  Fig. 45 exhibits tubercles in vari-
ous 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 disap-
peared 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.
  2. Carcinoma.  In cases of  true  scirrhus,  the matrix  or
stroma is constituted either by a new development of  cellular 
144               THE  MICROSCOPIST.^

texture, or by an induratkm  and enlargement of the original
areolar tissue of the part.  The larger and coarser fibres and

                          Fig. 45.
^
lamellae of this tissue beefime converted  into dense  and firm
ligamentous  bands,  which,, intersect  each otWer  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-men-
tioned whitish or ligamentous  bands, by being  insoluble in
acetic acid.  Fig. 46 (fronl Vdjgel, after Muller), shows the
Fig. 46.

fibrous stroma  of scirrhus,  as  seen in the microscope.  The
meshes are formed by bundles of carcinoma reticulare of the
breast, as they  appear after  the globules have been removed. 
MORBID STRUCTURES,  ETC.          145
   The dense, firm, bluish-white, or yellowish and amorphous-
looking 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,  ac-
quires 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  composi-
tion 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.  47.   Small masses that had been pared from
a  recent section  of the tumor, and moistened  in water,  con-
sisted entirely of an accumulation of  cells.   These were very
pale, varying in size and  form, being sometimes  roundish,  a,
sometimes oval, b,  or caudate, /, or  again of irregular form.
The greater number exhibited nuclei,  a, b, and in some a nu-
cleolus was visible  in the nucleus, c, h; few were  devoid  of
                            13 
146
THE  MICROSCOPIST.
nuclei;  on  some, fat globules  were observed, g.   Between
these cells were perceived nuclei with or without nucleoli, d.
(Vogel.)
                          Fig. 47.
  3. Encephaloid disease or fungoid tumor, differs from scir-
rhous cancer chiefly in the great predominance of its transitory
or morbidly developed cells over the fibrous and other elemen-
tary textures  which  constitute  the stroma (matrix) of the
tumor.  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 tumor.
Their great predominance in encephaloid, therefore, gives the
character of brain-like softness and yielding, which is the dis-
tinguishing characteristic  of this form of malignant growth.
  Fig. 48  represents encephaloid, 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 ren-
dered them full  and brought the  nuclei  plainly in view, a.
Here and there some  nuclei were  seen in an amorphous cyto-
blastema.
  Although the  cells of  encephaloid  belong  to the class  of 
MORBID  STRUCTURES,  ETC.          147
effete or transitory cells which also occur  in cancer, yet  there
is a difference in the proportions of various kinds of these cells
Fig. 48.
in the two classes of tumors.  The predominating cells of this
kind in  fungoid tumor are  the very large parent cells, with
numerous young cells or cytoblasts in their interior.   They are
often  as large  as g^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.
49 is the microscopic appearance  of encephaloid, consisting of 
148
THE  MICROSCOPIST.
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-
logy, the reader is referred to Vogel's Pathological  Anatomy,
and other similar works.
  The Monthly Journal  of  Medical Science for  May,  1847,
contained an account of a  new instrument for the diagnosis of
tumors.  It  was presented  to the Medical Society of  Stras-
bourg, 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 in-
strument into a tumor 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 tumor 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  investiga-
tion.   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 are appended. 
RESULTS OF DR.  GRUBY'S OBSERVATIONS ON  PATHOLOGICAL MORPHOLOGY.
TRANSLATED  BY S. J. GOODFELLOW, M.D.
A.  OF  MUCUS.
Healthy mucus and mucus generated by irritation and normal inflammation, are composed of an amorphous ductile
                              substance [proper mucus), globules, and epithelium.
Healthy Mucus.
Very few globules

Much of an amorphous
  substance  (proper
  mucus)
Contains but little epi-
  thelium
Globules from 2-4 times
  larger than the blood
  particles
No  molecules,  or  the
  smallest,  fill the glo-
  bules
Very thin  envelope to
  the globules
Not changed in water
MUCUS PRODUCED BY  NOR-
     MAL Irritation.
Very few globules

Very much of proper mu-
  cus

Contains  but  little  of
  epithelium
Globules from 4-5  times
  larger than the  blood
  particles
The smallest molecules fill
  the globules

Very  thin smooth en-
  velope
Globules swell in distilled
  water
MUCUS  PRODUCED BY
 SLIGHT NORMAL INFLAM-
 MATION.
Globules   more   nume-
  rous
Less mucus
Contains more epithelium

Globules 6-8 times larger
  than the blood particles

The  smallest  molecules
  (filled with), and a cen-
  tral vesicle
Smooth envelope

Swelled in distilled water

Envelopes easily broken
  in water
mucus  produced  by  a
 more  intense  normal
 Inflammation.
Globules   very   nume-
  rous
Much less mucus
Contains  very little epi-
  thelium
Globules  from%6-8  times
  larger  than the  blood
  particles
Filled with the smallest
  molecules and a central
  vesicle
Smooth envelope

Globules swell in distilled
  water
Envelopes easily broken
MCCUS   PRODUCED   FROM
 CHRONIC NORMAL INFLAM-
 MATION.
Globules very abundant

Very little mucus


Contains  very little  epi-
  thelium
Globules  6-8 times larger
  than the blood particles

Filled with  the  smallest
  molecules and a central
  vesicle
Smooth or no envelope

Swell in distilled water

Envelopes easily broken
CO 
MUCUS  PRODUCED  FROM  SPECIFIC OR ANOMALOUS INFLAMMATION CONTAINS, BESIDES  SUBSTANCES  PECULIAR TO

                                           NORMAL MUCUS,  OTHER  FORMS.
MUCUS GENERATED FROM TUBERCULOUS IN-
       FLAMMATION OF THE LUNGS.
Besides  the  products of  catarrhal in-
  flammation contains yellow lenticular
  Bpheres 1-8 times larger  than the glo-
  bules  of pus, concentrically striated,
  composed of concentric lamellae, which
  are dissolved in caustic potash
                      f They are in-
In nitric acid           creased 5 times
—solution of nitrate of  < in volume and
  silver               j become trans-
                      it parent
Some pulmonal cells and muscular fibres
  are seen in it
Dysenteric mucus.
Contains globules with central vesicles
  and molecules, round or ovate greenish
  corpuscles endowed with the smallest
  molecules, symmetrically disposed, and
  also  products  of catarrhal  inflamma-
  tion
Mucus of urethral blennorrhea.
Contains from the beginning a very few
  globules exceeding four times the dia-
  meter of the particles of the blood, and
  provided with the smallest  molecules
  and an envelope
On the third day it is composed of many
  globules, the smallest  molecules, an
  envelope, and central vesicle
On the tenth day till the vesicles  are en-
  dowed with central vesicles
They swell and are easily broken in water
On the fortieth day very few globules are
  found
                                                  B.  OF PUS.

Pus is composed of a certain white pellucid fluid and globules;  sometimes other substances are mixed with these.

                                 PUS  GENERATED BY NORMAL INFLAMMATION.
Or
©
Pus from a recent Wound. Pus from a recent Abscess. Pus from an old Abscess.  Pus from an old Wound.
Few globules
Contains more fluid
Globules from 4-6 times
  larger than those of
  the blood

With  very small  and
  larger molecules
Have one central vesicle
  and an envelope

Globules swell, and en-
  velope bursts in dis-
  tilled water
Many globules
Contains but little fluid
Globules 3-4 times larger
  than those of the blood
With very small and lar-
  ger molecules
One  or two central vesi-
  cles,  seldom without
  one
Globules  swell, and en-
  velope  broken  in dis-
  tilled water   _______
Many globules
Contains but little fluid
Globules 3-4 times larger
  than those of the blood
With very small and lar-
  ger molecules
With a central vesicle
Swell but  little in dis-
  tilled water
Fewer globules
liut little fluid
Globules 3-4 times larger
  than those of the blood
Contains a good  deal of
  epithelium
With very small and  lar-
  ger molecules
No central vesicle
Does not swell in distilled
  water
PU.H FROM THE SURFACE OF
 AN ORGAN WHOSE CONTI-
  NUITY IS UNINJURED.
Fewer globules
Much fluid
Globules 6-8 times larger
  than those of the blood
Contains but little epithe-
  lium
With very small and lar-
  ger molecules or none
Composed  of a central
  vesicle full of molecu-
  les, or none at all in it
Sometimes swell in dis-
  tilled water 
PUS FROM  SPECIFIC INFLAMMATION.
1. Generated during the Variolous Process.			2. Generated in the Tuber-
A. During TnE formation of papula.	B. During the formation of vesicles.	c. durino the formation op pustules.	culous Process.
The pellucid fluid extricated offers an alkaline reaction. Is composed of a white pellucid fluid and a few free molecules of the larger and smallest kind, and animalcules On the third day after the erup-tion larger molecules and a few white almost pellucid glo-bules 2-3 times larger than those of the blood Filled with the smallest mole-cules Molecular motion scarcely to be seen Animalculae are found in it	On the 4th day a little limpid serum Contains globules endowed with the smallest and larger mole-cules, and a central vesicle The envelopes are not easily broken Vehement molecular motion Animalcules, and free very small globules On the oth day the turbid serum has an alkaline reaction Contains globules of the larger yellow molecules The envelopes are easily broken The molecular motion and ani-malcules are well seen	On the 6th day the thicker yel-low fluid has but a slight al-kaline reaction The globules 4 times larger than those of the blood, many with an envelope easily to be broken or without one Filled with the smallest or the larger molecules, and some-times provided with a central vesicle The molecular motion dimi-nished On the 7th day and beyond, the yellow thick fluid contains many globules adhering to-gether The envelopes are very easily broken, the molecules dissi-pated without order Cells of epithelium and drops of fat are frequently seen in it	See—Mucus produced from Specific Inflammation.
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.
WHITE, OR GREENISH-WHITE, LIMPID, EXUDATED, SEROUS FLUID IS COMPOSED OF A PELLUCID FLUID AND GLOBULES.
Serous Exuda-tion OF A BLAD-DER produced BY BUSTER.	Serous Exuda-tion FROM CRUDE INFILTRATION OF INTESTINAL TY-PHUS.	Serous Exuda-tion EXTRACTED FROM THE PAPU-LA OF MODIFIED VARIOLA.	Serous Exuda-tion EXTRACTED FROM THE FI-BRINE OF A VIL-LOUS HEART.	Serous Exuda-tion FROM A HY-DR0CY8T.	Serous Exuda-tion FROM OSDE-MA OF THE CUTIS.	Serous Exuda-tion EXTRACTED FROM THE SUB-STANCE OF AN IN-FLAMED HUMAN PLACENTA.	Serous Exuda-tion FROM THE vaginal dis-charge IN THE THIRD PERIOD OF PREGNANCY.
Contains white globules with a very thin covering filled with the small-est molecules, or destitute of all covering 1-2 larger than the blood glo-bules	Contains white globules with an envelope filled with the smallest mole-cules. 1-2 larger than the blood glo-bules	Contains white globules with a very thin covering filled with the small-est molecules 1-4 times larger than the blood globules	Contains white globules, con-sisting of a very thin en-velope, filled with the small-est molecules 1-2 times larger than those of the blood	Contains per -fectly round white globules destitute of molecules. Scarcely larger than the glo-bules of the blood	Contains white or yellowish-white stella-ted globules, scarcely larger than those of the blood Here and there provided with a small nu-cleus	Contains white globules, with an envelope filled with the smallest mole-cules 1-2 times larger than those of the blood	Contains white globules, with an envelope filled with the smallest mole-cules Once to twice larger than the blood discs
D. THE MORPHOLOGY OF THE GLOBULES GENERATED DURING THE PATHOLOGICAL PROCESS.
1. THOSE WHICH OCCUR IN MUCOUS MEMBRANE.
IN HEALTHY MUCOUS MEM-BRANE.	In irritated mucous membrane.	In slightly irritated mu-cous MEMBRANE.	In a more intense inflam-mation OF MUCOUS MEM-BRANE.	In chronic inflammation of a mucous membrane.
Very few yellowish-white globules are generated provided with a co-vering, and enclosing none or very few of the smaller molecules They are not changed in water, and are from 2-4 times larger than those of the blood	Very few yellowish-white globules are generated They are provided with an envelope, enclosing the smallest molecules, and arc 4 times larger, than the blood globules, and swell in water	More copious or abundant yellowish-white globules are generated. They are provided with an enve-lope, filled with the smallest molecules and a central vesicle, and swell, and are broken in water. They are 8 times larger than the blood globules	The yellow globules are generated in greater abundance, 8 times lar-ger than the blood glo-bules, endowed with an envelope, filled with the smallest molecules, and a central vesicle They swell, and are bro-ken, in water	The yellow globules are generated in the great-est abundance, are 8 times larger than the blood globules, endowed with an envelope, or an envelope with the small-est molecule*, and a cen-tral vesicle
 
2. THOSE WHICH ARE GENERATED IN THE  SKIN.
By the application of a BLISTER.	By the'variolous process under the formation of PAPULE.	By the variolous process during the formation OF vesicles.	By the variolous process during the formation of pustules.	By THE VARIOLOUS PROCESS DURING THE FORMATION OF CRUSTS.
A very few white globu-les, 2-3 times larger than the blood globu-les, endowed with no envelope, or one filled with the smallest mole-cules Water does not change them	A very few white globu-les, 2-3 times larger than those of the blood, pellucid, endowed with a very thin covering, enclosing the smallest molecules They swell in water	Numerous yellowish-white globules, 3-4 times larger than those of the blood, endowed with an envelope, filled with the smallest and larger molecules, and a central vesicle They swell, and are bro-ken, in the water	Very numerous yellow globules, 4-5 times lar-ger than those of the blood, provided with the smallest and larger mole-cules, and the central vesicle They swell in water, and are easily broken	A few yellow whole glo-bules, 4-5 times larger than those of the blood: many lacerated, fur-nished with no envelope, or with one filled with the different molecules. They are easily broken.
3. THOSE WHICH ARE GENERATED IN SEROUS MEMBRANE.
Hydrocysts.	OF THE PERICARDIUM UNDER THE FORMATION OF THE VILLOUS HEART.	OF AN INFLAMED PERITO-NEUM.	OF AN INFLAMED PERITO-NEUM NEONATI.	Of a very acutely inflamed peritoneum.
White, pellucid, perfectly round globules are formed scarcely larger than those of the blood, with an envelope desti-tute of all molecules They are not changed in water	White globules, 2-3 times larger than those of the blood, endowed with a very thin envelope, filled with the smallest mole-cules They swell in water	Yellowish-white globules, 3-6 times larger than those of the blood,formed with an envelope, filled with the smallest and larger molecules They swell in water	Yellowish-white globules, 4-8 times larger than those of the blood, com-posed of a very fine en-velope, with a few very small molecules or none, and with a central vesi-cle, either filled with the smallest molecules, or possessing none They are not changed by water	Yellow globules, 4-8 times larger than those of the blood, either with a very thin envelope partly or entirely filled with the smallest or larger mole-cules, or with no enve-lope They are not changed by water
 
THOSE WHICH ARE GENERATED IN PATHOLOGICAL  (DISEASED)  PARENCHYMA.
Or CRUDE, RECENT INFILTRATION OF THE ILEUM.	OF THE RED INFILTRATED MESEN-TERIC GLANDS IN ABDOMINAL TYPHUS.	IN THE PROCESS OF PURULENT IN-FILTRATION OF THE CELLULAR TISSUE.	IN THE SOFTENED MESENTERIC GLANDS IN ABDOMINAL TTPHU3.
The globules are white diapha-nous, scarcely exceeding the diameter of the blood globules, with a smooth envelope filled with the smallest molecules They swell but little in water	Yellowish-white diaphanous glo-bules exceeding from 2-4 the globules of the blood, composed of an envelope filled with the smallest molecules, or 6 times larger than those of the blood, with an envelope filled with the smallest molecules and a central vesicle, of many mole-cules	Bound yellowish-white globules, exceeding 4 times the magni-tude of those of the blood, com-posed of an envelope filled with the smallest molecules They swell but little in water	Round yellowish-white globules 4-8 times larger than those of the blood, composed of an en-velope with the smallest or larger molecules They swell in water
Of a hepatized recent placenta.		IN THE EXUDATION OF PLASTIC LYMPH IN CROUP.	
White globules scarcely exceed-those of the blood, composed of an envelope, filled with the smallest molecules		Bound yellowish white globules exceeding 3 or 4 times the size of those of the blood, composed of an envelope filled with very small molecules They are not changed by water	
OF A HEPATIZED SPLEEN.	•		
White globules equalling in mag-nitude the globules of the blood, or twice as large, with or with-out an envelope, but if with one it is filled with the smallest molecules They are not changed by water			
 
THOSE  WHICH ARE GENERATED ON THE  SURFACE OF A PATHOLOGICAL (DISEASED) ORGAN.
EXPOSED.
IN THE TENTH HOUR OF A RECENT WOUND.	Of pus of a recent wound 24 hours and beyond.	Of pus in the seventh week of a recent wound.	From an old wound suppurating but little.
A few round, white, transparent globules 1-3 times larger than those of the blood, composed of a very thin envelope filled with the smallest molecules They swell but little in water	Bound yellowish-white abun-dant globules 4-6 times larger than those of the blood, en-dowed with a very thin enve-lope with the smallest and the larger molecules, and also a central vesicle They swell in water	Very numerous round yellowish globules 5-8 times larger than those of the blood composed of an envelope with the smallest molecules and a central vesicle They swell and their envelopes are broken in water	A few yellow roundish globules 2-4 times larger than those of the blood, composed of a dense envelope full of the smallest molecules They are not changed by water
SHUT.                                                   <3
Of a recent idiopathic abscess of the abdomen.	Of idiopathic abscess of the LIVER.	Of an old idiopathic abscess.	Of a metastatic abscess of six days' standing.
Bound or oblong yellow globules 4-6 times larger than those of the blood, composed of a very thin envelope, with the very small and larger molecules, either with or without a cen-tral vesicle, or a simple or double one They swell in water and their envelopes burst	Round yellow globules 3-4 times larger than those of the blood, composed of a thin envelope full of the larger and a few of the largest molecules They are changed but little in water	Yellow round globules 4-6 times larger than those of the blood, composed of a very thin enve-lope, endowed with the small-est molecules: some have no envelope They swell in water	Round globules 1-3 times larger than those of the blocd, com-posed of the smallest molecules, but seldom of an envelope Are not changed by water
 
Mucus IS composed
2. Of the thick pellucid
    ductile fluid.
3. Of Epithelium.
1. Of Globules.
	Round 6-8 times larger than those of the blood	FORM OF THE GLOBULES.
		MAGNITUDE.
		
White or yellow		COLOR.
	CO B o o E?	ENVELOPE.
	COB o"-< <2, re- re	CENTRAL VESICLE.
	The very 'small and the larger	MOLECULES.
	Enve-lopes are broken	DISTILLED WATER.
No change pro-duced	Dis-solves the en-velopes and the very small mole-cules. The nuclei 1-6 re-main clearly to be seen.	ACETIC ACID.
No change pro-duced	Dis-solves the en-velopes and the very small mole-cules	OXALIC ACID.
No change pro-duced	Quick-ly dis-solves the en-velopes, the white vesicle remain-ing.	TARTARIC ACID.
p JsTg	Corru-gates the en-velopes	NITRIC ACID.
i»2	Corru-gates the en-velopes	MURIATIC ACID.
	Corru-gates the glo-bules, and tinges them of a yellow color	SOLUTION OF THE NITRATE OF SILVER.
Forms fila-ments, which are more slowly dis-solved in it	First dis-solves the en-velopes, more slowly the very small mole-cules and nuclei	CONCENTRATED SOL. OF NITRATE OF SILVER.
	re g a S. ° re	PURE AMMONIA.
	B" s, °	LIME WATER.
	Dis-solves the globu les; the white mu-cous fluid re-mains	PURE POTASH.
	Con-tracts the globu-les	SPIRITS OF WINE.
'ISiaOQSOHOIH   3HI
991 
ss,
HH <W *3
r-ici
S ° -1
9i_, S>
	H ™ H g			M	«3 S2	H	a	3	g	o	p	o	°5«	5 2 «		(3	a	6.
	§ o	eh -<	M o o	o .J w > H		i o S3	3 M S EH & ■< 3*	M	■4 o o	9a eh	o 3	B "<	as * H h *= 3 IBs	« H S a &, s §°*	n o	Eh 1 2	Eh O P. W B CM	
(	Round	3-4	White	Smooth	One or	The	Enve	Dis-	Dis-	Very	Corru-	Corru-	Corru-	Ren-	No	No	Dis-	
\	or ob-	times	or	or	two,	very	lopes	solves	solves	quickly	gates	gates	gates	ders the	change	change	solves	
)	long	longer	yellow	none at	sel-	small	are	the en-	the en-	dis-	the	the	the	glo-			the	the
<,		than		all	dom	and	bro-	velopes,	velopes,	solves	enve-	enve-	globu-	bules			glo-	globu-
J		those			none	the	ken	the 2-5	the 2-5	the	lopes	lopes	les, and	trans-			bules,	
/		of the				larger		nuclei	nuclei	enve-			gives	parent,	.		the	
		blood						remain	remain	lopes			them a yellow tinge	the con-tracted nucleus remain-			mu-cous fluid remain-	forms from 1-5 nuclei
									1					ing			ing	
f								Pro-	Pro-	Pro- 1 Forms		Forms	Forms	Forms				
i								duces	duces	duces no fila-		no fila-	no fila-	no fila-				
1								no	no	no ments		ments	ments	ments				
		t					change change change'											
 
CHAPTER  XL
               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  collapsed; 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 ramifica-
tions may be clearly seen.   More 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 to-
gether 16 ounces of  bees'-wax,  8  ounces of resin, and 6 fluid-
ounces of turpentine varnish, adding such coloring 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.
159
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 are required.
Indeed, it is so difficult an art, and success is so dependent on
the combination  of various circumstances, that the most ex-
perienced 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 in-
strument 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.  50  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, D,  also unscrews, for convenience  of
cleaning.  E is a stop-cock, on the end of which another stop-
cock, F, fits closely.   On the end of this, one of the injection-
pipes, 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 for-
wards.   A  half-dozen pipes, at least, are necessary to accom-
pany 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 injec-
tions, will be found useful.
  For very minute injections,  as in the Mollusca,  &c, a caout-
chouc bottle,  with a capillary steel  tube mounted in wood, 
160
THE  MICROSCOPIST.
ivory, or iron, is recommended by Talk & Henfrey, after Straus
Durekheim.  The air should be pressed out of the bottle, and
Fig. 50.
the pipe placed in the liquid, which  will rush  in  to  fill the
vacuum, and it is ready for use.   They also recommend  a tube,
or pipette, with flexible stems, so constructed as to receive jets 
ON  MINUTE  INJECTIONS.
161
of various sizes.   This is used by placing the end of the pipette
in the mouth, and exhausting the air on forcing the fluid in the
vessels.
   To prepare the material for  injecting:—Take  of  the finest
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 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 the froth
from the surface, and strain through a flannel  for use.  Isin-
glass, and cuttings of parchment make an excellent size, and
are preferable for very particular injections.
   The size thus prepared may be colored  with any of  the fol-
lowing:
   Red.—To 1 pint of size, 2 ounces  of Chinese vermilion.
   Yellow.—Size, 1 pint,—chrome yellow, 2£ ounces.
   White.—Size, 1 pint,—flake-white, 3 J ounces.
   Blue.—Size,  1 pint,—fine blue smalts,  6 ounces.
   It is necessary to remember that whatever  coloring 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 color, 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 color should be frequently stirred,
or the coloring 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 injec-
tion.
   Owing to the contraction  of the  vessels, it is necessary to
wait from one to three days after death before attempting the
                             14* 
162
THE  MICROSCOPIST.
injection.  Yet it should not be deferred so long that the ves-
sels may become softened, or the injecting material will be ex-
travasated.
  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.
  When the size and the subject have both been properly pre-
pared, have  the injection as hot  as the finger  can well bear.
One  of the pipes,  Gr, Fig.  50, must  then be  placed in  the
largest  artery of the part,  and securely tied.   Put the stop-
cock, 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.
  If the  resistance suddenly ceases or diminishes, it indicates
that  some vessel is ruptured, and the process must be stopped.
If it  happens at  the commencement of  the operation, and the
vessel cannot be tied, the injection has failed.
  When as much injection is passed as may be thought advisa-
ble, the preparation may be  left (with  the stop-cock closed in
the pipe) for twenty-four hours, when more material may be
thrown  in.
  The first part of the injecting material forming about a third 
ON MINUTE  INJECTIONS.
163
 or  fourth part of the whole, should be very fluid, so as to be
 capable  of  penetrating the  smallest vessels;  afterwards the
 thicker or coarser portion should be thrown in so as to push the
 first before it.
   As  the method  of  injecting the minute  capillaries  with
 colored size  is often attended with doubtful success, various
 other plans have been proposed.   Ruysch's method, according
 to Rigerius, was  to  employ melted tallow, colored with vermi-
 lion, 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  colored 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  coloring
 matter extracted from campeachy, fernambouc, or sandal woods.
 He says, "The coloring matter of campeachy wood easily dis-'
 solves in water and  in alcohol; it is so penetrating that it be-
 comes 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 solu-
 tion of caoutchouc.
  Another process, which may be termed the chemical process,
was published in the Comptes Rendus, 1841, as the invention of
M. Doyere, though the credit of first suggesting it  is due to Dr.
 Goddard, of Philadelphia.  According to this, an aqueous solu-
tion of bichromate of potass  is propelled into the vessels; and 
161
THE  MICROSCOPIST.
after a short time, in the same  manner and into the same ves-
sels 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 color.
  A red precipitate is obtained by iodide of potassium and bi-
chloride of mercury; blue, by  the ferrocyanide of  potassium
and peroxide of iron ; &c.
  Dr. Gloadby 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. Gr. 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 colored  infiltrated  gelatine  (by   which,  he
alludes to the gelatine, colored by the blood, which, together
with the acetate of potash resulting from the chemical decom-
position, may have transuded through  the coats of the vessel),
which, when dry, forms, together with the different shades of
the chromate of lead, beautiful objects,  possessing  depth and
richness of color.  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 de-
tected  by the altered color imparted by the blood.
   " Those preparations which  require to be kept wet, can be 
ON MINUTE  INJECTIONS.
165
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 chemico-
gelatinous injection.   Where so much wet abounds gummed
paper is apt to come off.
   " When dry, it is sufficient  for the purpose of  brief exami-
nation 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.
   "Although  highly  desirable, as  the  demonstrator of the
capillaries  of normal tissues, I do not think this kind of injec-
tion  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 exa-
mination by the microscope, I have  tried the effect of dilute
nitric acid, as a corroder,  with  very good  results.   But, proba-
bly, liquor potassse would have answered  this purpose better.
   "When size injection is to be employed, colored either with
vermilion or the  chromate of lead, the animal should  be pre-
viously 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  coloring  matter.
Hence the difficulty of procuring good injections of the human
subject.
   "But with the 'cheniico-gelatinous'  injections  no such pre-
paration is necessary,  and success should  always be certain, for
the potash liquefies the blood, while constant and long-con? 
166
THE  MICROSCOPIST.
tinued pressure by the syringe drives it through the parietes of
the vessel into the cellular tissue.   The large quantity of  in-
filtrated  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, and in  some respects a more certain and con-
venient plan, has been employed by Dr. Goddard of Philadel-
phia.   It consists in adding a quantity of sulphuric ether  to
the finely levigated coloring  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 suc-
ceeded 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 coloring matter.   I have
also observed that  after  the ether has evaporated from the
vessels, the particles of coloring material cohere with too little
tenacity, so  that on  putting  a section of injected  tissue into
turpentine, &c, the  color has been washed out  from  the cut
ends of the larger vessels.  Perhaps  a  solution  of  gum mas-
tich, &c, in  ether, colored with fine vermilion, &c, will answer
the indications better.
   Whatever mode of injection be adopted, it is important that
the operator be supplied with  sufficient material.   The quantity
which can be  used will surprise any one unaccustomed to the
process.
   A foetus maybe 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.
   The liver, kidney, &c, may be well injected out of the body;
and it is  often desirable  to use various colors for the different
sets of vessels.  It will require some practice, however, to judge 
ON MINUTE  INJECTIONS.
167
 how much pressure is necessary to fill but a single set of vessels.
 After injection, a considerable time must  be allowed for dry-
 ing.   Thin slices may then  be cut  off,  and mounted either in
 balsam or fluid.
   The villi of the intestines  are  beautifully exhibited after in-
 jection.   They should be macerated a little while in water, or
 washed with a syringe, to remove the epithelium and mucus.
 Animals that feed chiefly on vegetables  have longer villi than
 others.
   The lungs may be injected by  the pulmonary artery or vein-
 In a foetus, however, all the  organs  may be injected from the
 umbilical vein.   The author's  injections and  specimens  of  in-
 jected lungs confirm the view  of Mr. Rainey, that the  essen-
 tial and only true organs of  the aeration of the blood  are the
 pulmonary capillaries.
   Injections of  the  skin may be  made  by the vein of an ex-
 tremity.   They  may then be mounted in fluid, or after drying,
 sections may be  made and put up in balsam.
   The vessels of the choroid  membrane and ciliary processes of
 the eye are often injected in a  foetus; or in the case of an animal,
 as a cat, rabbit,  &c, injected from the heart.  The preparation
 should be kept in fluid.
   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 care-
 fully handled, or moved, in the macerating liquor, as the slight-
 est 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 me-
thod for the  colored material, on account of the mercury fre- 
168
THE  MICROSCOPIST.
quently 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 in-
jecting the lymphatic  system of a  lizard, tortoise, &c, he re-
marks :—" 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 intro-
duce into it the small extremity of  the syringe, and push the
piston with a force always decreasing."   He   recommends
colored wax, mixed with nut-oil, for the injection. 
CHAPTER  XII.
      EXAMINATION OP  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  acid and its  combinations (called  red, or
yellow-sand sediments), occur in  fever; acute  inflammation;
in rheumatism;  in phthisis; in all the grades  of dyspepsia;
in all or most stages of diseases  attended  with  arrest  of per-
spiration ; 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 simul-
taneously  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
                             15 
170
THE  MICROSCOPIST.
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.
  Albuminous urine occurs  in  Bright's  disease, dropsy after
scarlatina, &c.
  Pus is met with in the urine as  the result of suppuration of
the kidney, or of some part of the genito-urinary mucous mem-
brane, or of  abscesses of  the neighboring  viscera, opening
into the urinary passage.
  The presence of  sugar  is not uncommon in dyspepsia, and
when excessive is diagnostic of  diabetes mellitus.
  Kiestein 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 remain-
der 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  OP  URINARY  DEPOSITS.   171

   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 de-
 posits a  sediment of  earthly 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-colored mould.
   Urea 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  crystal of oxalate of urea  thus
 obtained, a, Fig. 51, 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 puri-
 fied  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. 51, by
 concentrating urine  to about one-half its bulk, and adding an
 equal quantity of nitric acid.   If urea be suspected in excess,
 g, 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  1-0 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 
172               THE  MICROSCOPIST.

a few drops of hydrochloric acid, and  allowing it  to stand  a
few hours in a cool place.

                           Fig. 51.
  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.  52 represents some
Fig. 52.
of its forms; a are deposited from an alcoholic  solution, and
6 from a hot aqueous solution/
   When an excess is  suspected in urine, it should be  evapo-
rated to the consistence of syrup and mixed with half its bulk
of strong  hydrochloric acid.   After a few  hours the crystals 
       EXAMINATION  OP  URINARY  DEPOSITS.    173

 may be  examined with the microscope, when  the tufts  will
 probably be seen, colored pink by the  admixture of purpu-
 rine.  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.
   Vesical Mucus and Epithelial  Scales, which may be present,
 are derived from the internal  surface of the bladder and  uri-
 nary 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 Matter, 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 ap-
 pears more highly colored than usual, a large proportion of
 what is  termed extractive, consisting of coloring  matter, as
 purpurine, &c.
  Ammoniacal 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 ki^ds 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  for-
mer  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, chlo-
ride  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. 53.  The cross-
                            15* 
174               THE MICROSCOPIST.

lets consist of  chloride of sodium; the more plumose crystals
are probably phosphate of soda.

                           Fig. 53.
   The Earthy  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 re-
tained 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 ingre-
dients found in morbid urine, &c, 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 considera-
ble quantity may be retained in solution, while if it be neutral
or alkaline, a comparatively small proportion may be precipi-
tated. 
       EXAMINATION OP  URINARY  DEPOSITS.   175

   When urinary deposit is examined with the  microscope, it
 will  be found  either  crystalline,  amorphous,  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 phos-
 phate is formed), oxalate of lime, or perhaps cystine.  "
   Triple Phosphate.—This salt (called also the  double phos-
 phate 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.  54.   They  disappear on  the  addition
 of acetic acid.
   Uric (or  Lithic)  Acid.—This  salt,  like the earthy phos-
 phates, 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 assis-
 tance in diagnosis.
  It is insoluble in alcohol, and  nearly so in  dilute hydro-
 chloric  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 (C8 N2 H4 O10), alloxantine  (C4 H3 N3 0B),  and other
 compounds.   This may be evaporated nearly to dryness, when
a red residue will be left, which, when cold, should be moist-
ened with ammonia,  which will develope  a beautiful purple
color, owing  to the formation of murexide (Cu N5 H6 08 ). 
176               THE  MICROSCOPIST.

  The crystalline forms of uric acid are various, but appear to
be modifications of the rhombic prism.

                           Fig. 54.
  Fig. 55 represents some of its forms.
   Oxalate of Lime often exists in the form of minute octahe-
dral  crystals, varying from 75oth  to gg^th of an  inch in
diameter,  a, Fig. 56.   When allowed to dry on the glass, each 
      EXAMINATION  OP  URINARY  DEPOSITS.   177




crystal appears under the microscope like a black cube, having
Fig. 55.

o
0  ®
<o
in the centre a small white square opening,  as shown at b. 
178
THE  MICROSCOPIST.
This is owing to the rays of light being mostly refracted be-
yond the field of vision.   On again moistening them, the crys-
tals reappear in their octahedral form.  Sometimes  this salt
                           Fig 56.
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.     179

triple phosphate,  &c,  is  beautifully colored 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.  57.  At  b is the form left from  the
ammoniacal solution.
                           Fig. 57.
  Amorphous Deposits consist  probably  of phosphate  of
lime, urate of ammonia, urate of soda, fat, or chylous matter.
  Phosphate of Lime.—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 (before 
180
THE  MICROSCOPIST.
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  pre-
cipitated by ammonia.  They are  insoluble in a solution of
potash.
   Urate of Ammonia 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  par-
ticles, 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 preci-
pitated 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 re-
sembles 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 per-
ceived with  the microscope.  In such cases, the  urine may be
agitated with  a little  ether, which will dissolve  the fat,  and 
       EXAMINATION  OP  URINARY  DEPOSITS.   181

the solution  so  formed will separate from the watery liquid,
and form a distinct stratum on the surface.
   Chylous  Matter 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  colorless  globules,  which  may
possibly be mistaken for oil globules, from which their insolu-
bility in ether distinguishes them.
   Organized Deposits may either be mucus, usually mixed
with epithelium; pus; blood;  or semen.
   Mucus.—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 gentle
                             16 
182
THE  MICROSCOPIST.
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 bot-
tom examined.  The urine may also be tested for albumen after
separating the solid matter  by filtering.  When the coloring
matter of the blood is  present, it will  coagulate with the albu-
men, giving  it a  red or brown color.  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 color 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 treat-
ing with warm alcohol,  or  may be precipitated by adding a
little warm aqueous solution of urate of ammonia, which on cool-
ing will fall down, carrying with it the coloring 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,  piuk, and  yellow, the  color
rapidly  changing as the  acid mixes with the  urine.   When
only slight traces of bile are  present, the urine should be con-
centrated by evaporation.
  When semen is present in urine, it  may  easily be  detected
under the  microscope, by the appearance of minute animalcu-
les, always found in the spermatic fluid, and  hence called sper-
matozoa.   They are oval in shape, with long  and delicate tails.
Traces of albumen may generally be detected in urine contain-
ing semen. 
       EXAMINATION  OF URINARY DEPOSITS.    183

   Diabetic and Albuminous Urine.—Albumen  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 phosphate, it will
be necessary to add a  few drops of nitric acid, which will re-
dissolve the phosphates but leave the  coagulated albumen un-
affected.   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.   Se-
veral tests have been proposed for its detection in urine.
   Trommer'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 pre-
cipitated in the  form  of  a  reddish-brown or  ochre-colored
granular powder.
  Moore's Test is made by mixing a little  suspected urine  with
half its volume of liquor potassse and  boiling gently for about
five minutes.  If sugar is present, the liquid assumes a brown
or bistre tint.
   The Fermentation 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 fermenta-
tion, by which it becomes converted into  alcohol and carbonic 
184              THE  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 from 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. 58, which, in

                          Fig. 58.








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  num-
ber 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 Me-
dical 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 Philadel-
phia, in one convenient volume.   The "Analysis" of  Dr. Rees
contains also a valuable essay on the treatment of urinary dis-
eases.
 
EXAMINATION OF  URINARY DEPOSITS.   185
                        TABLE  I.

FOR  THE  CHEMICAL EXAMINATION  OF URINARY
                        DEPOSITS.
   1.  The sediment  dissolves when warmed.   Urate of Am-
monia. <*-^ &*~*-»-»-W  e<5-C<U*£w
   2.  Not soluble when  warmed,  but soluble in acetic  acid.
Earthy Phosphates.
   3.  Insoluble in acetic,  but soluble  in  dilute hydrochloric
acid.   Oxalate of Lime.
   4.  Insoluble in dilute  hydrochloric acid.   Purple with nitric
acid and ammonia.  Uric 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 por-
tion coagulable by heat and nitric  acid.  Blood ?
   8.  Soluble in ammonia; the solution leaving, on evaporation, y ;
hexagonal crystals.  Cystine? QvuJ^^^^^L/1^/,\ CZeuce^J^  >
   9.  Yellowish  sediment,  soluble  when warmed.    Urate of
Soda ?
   10.  Ether yields,  after  agitation, an oily or fatty  residue.
Fatty Matter.
   11.  Milky appearance.  Chylous Matter.

                        TABLE  II.

FOR  THE  EXAMINATION OF  THE  CLEAR  LIQUID
                        PORTION.

   1. Crystals with nitric acid.  Excess of Urea.
   2. Fermentation, or Trommer's test.   Sugar.
                            16* 
186               THE MICROSCOPIST.
  3.  Precipitate formed  on boiling; soluble in nitric acid.
Excess of Earthy Phosphates.
  4. Precipitate formed on boiling; insoluble in nitric acid.
Albumen.
  5. Precipitate formed by nitric acid.  Excess of Uric Acid,
or Albumen.
  6.  Concentrated urine yields needle-shaped crystals  with
hydrochloric acid.  Hippuric Acid.
  If the urine is highly colored,
  7. Dark coagulum formed on boiling.   Blood ?
  8. Red color with  hydrochloric  acid.  Excess of Coloring
Matter.
  9. Pink precipitate with warm solution of urate of ammonia.
Purpurine.
  10.  Change of color with nitric acid.  Biliary Matter.

                       TABLE III.

FOR  MICROSCOPIC  EXAMINATION  OF DEPOSIT.

                      If Crystalline.

  1. Lozenge-shaped, &c.   Uric Acid. O^v ^a^^^-J OAc^v
  2. Stellae, or three-sided  prisms (after  saturating with  am-
monia).   Triple Phosphate. (1y^~^?^^
  3. Octahedra, or dumb-bells.   Oxalate of Lime.  pvVu^iw'
  4. Rosette-like tables.    Cystine.   *^■ «*~\~Jlr *rf"**-fr c^t

                      If Amorphous.

  5. Soluble when warmed.   Urate of Ammonia.   "\\ Vl^vv^-M^ wi
  6. Soluble in acetic acid.   Phosphate of Lime.   *•   ?    T' ^ J « /
  7. Yellowish grains.   Urate of Soda ? fy/\ (]^\^4J^y^~oA^\^, 
    EXAMINATION OF  URINARY DEPOSITS.   187

8. Round globules with dark edges.   Fatty Matter.
9. White and milky.  Chylous Matter?

                    If  Organized.

10. Granulated corpuscles, in stringy aggregations.   Mucus.
11. Irregularly shaped scales.   Epithelium.
12. Detached granulated corpuscles.   Pus.
13. Blood-corpuscles.  Blood.
14. Spermatozoa.  Semen.
<6*J ^^/U^-i^^/er-^irkj^i^.i^^i^ Im^^Ju^jl^o^
<c.
JU^,^.                              —^—y »^«^«. «f*^*tr
-aeey A^^l^ ^^^f-d^t^jt—
^% 
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 trans-
mit it through a thin plate of either  of them, it will  be  re-
flected 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 color.
  " The same property belongs to light emitted from a candle,
or any burning or  self-luminous body, and all such light  is
called common light.  A section of such a beam of light will 
ON POLARIZED  LIGHT.
189
be a circle, like A, B, C, D, Fig. 59, and we shall distinguish
the section of a beam  of common light by a circle  with  two
diameters, A B, 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. 60, and  examine the  two
Fig. 60.
 circular beams, 0 o, E e, formed by double refraction, we shall
 find,
   " 1. That the beams 0 o, E e, have different properties on dif-
 ferent sides; so that each of them differs, in this respest, from
 the beams of common light.
   " 2. That the beam 0 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 D', as  shown in Fig. 59;
 or, in general, that the diameters of the beam, at the  extremi-
 ties of which  the beam has  similar properties,  are  at  right
 angles to each other.
   " These two beams, 0 o, E e, Fig. 60,  are therefore said to
 be polarized, 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, 0 o, E e,  Fig.  60, to be united into one, we obtain a
beam  which has exactly the same properties as the beam A, B, 
190
THE  MICROSCOPIST.
C, D, Fig. 59, of common light.   Hence we infer, that a beam
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  means of polarizing  light besides that of
double refraction,  just mentioned.   M.  Malus  discovered, in
1810, that a beam of common light, reflected from glass at an
angle of 56°, or from water at an angle of 53° became  polar-
ized.
  In order to  explain the phenomena of polarized light when
produced by reflection from glass, let C,  D, Fig.  61, represent

                           Fig. 61.
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 window-
shutter, 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 suffer reflection 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,
 
ON POLARIZED  LIGHT.
191  .
 will become brighter and brighter till the tube has been turned
 round 90°, when the plane of reflection from B is coincident with
 and 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 90° 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. 62, to pass through bundles of glass plates, A,  B,  in-
                           Fig. 62.

                 a_^f    JM__


 clined at the proper angle.   If the bundle of plates,  B,  be
 placed as [in  the  figure, the  ray  s r,  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 trans-
 mitted, as seen at  v w.   If  B  is now turned round its  axis,
 the transmitted light, v w, 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 w, will  disappear, and  all the
 light will be reflected.   Alternate transmissions and reflections
 will thus take place in every quadrant,  as in the former  case.
 For the ray passing through the tube in Fig. 61, or the ray,
s r, 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. 60, or we may  employ with even greater  ad-
vantage the single  image prism 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 
192
THE  MICROSCOPIST.
touching the obtuse solid angles.   The cut surfaces having been
carefully polished, were then  cemented  together with  Canada
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. 62, just
described.  One of the prisms is adapted to the under surface
of the stage,  and is called the polarizer; the other, called  the
analyzer, 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 color  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 colors, and systems of colored  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 colors:—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 
ON POLARIZED  LIGHT.             193
of an inch thick), so that the polarized beam may pass through
it perpendicularly.  It should be placed between the polarizer
and the analyzer, 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 colors.  If the film  be turned
round, still keeping it perpendicular to the polarized ray, the
colors will become less or more bright, and two positions will
be found, at right angles with each other, wherein no colors
at all are perceived.  If the analyzer be turned round, the film
retaining  its  position,  complementary colors  will   alternate,
together with points of  invisibility, during each revolution.
   The colors 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  land-
scapes 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 colors.
   Various crystals exhibit, round their axes of double refrac-
tion, beautiful systems of colored  rings,  often  intersected by
a  black cross.  Complementary colors  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 colors 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 re-
fraction in the direction of  the polarized beam.   All  such,
                             17 
194
THE  MICROSCOPIST.
therefore, will exhibit colors, as will those also in which the
thickness of the crystal is not below the proper standard.
   After  the polarizing apparatus  is adjusted, as before de-
scribed, the crystals properly mounted may be placed  on the
stage, in the same way as ordinary objects.   Some few vege-
table structures may be exhibited in  the same manner, as the
siliceous  cuticle  of  equisetum, starch,  &c.   Many  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 colored. If  the film be of  unequal
thickness, the colors 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 diffe-
rences in density between any two or  more parts of the same
substance that can at all approach  it in delicacy.  All struc-
tures, 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 es-
pecially be investigated by polarized light.    Some of the most
delicate of the elementary tissues of animals, such as the tubes
of nerves, the  ultimate  fibrillae 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 for Polarized  Light. — 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, 
ON POLARIZED  LIGHT.
195
&c, to preserve them from injury by the pressure of the glass
cover), or in Canada balsam.   If it be desired to examine  the
crystals during  their formation, the crystallization should be
carried on in a glass that is slightly concave.  All those crys-
tals that are so thin as not  to  exhibit  color, may have color
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 micro-
scope 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  MIC R 0 SC 0 P I S T S.

  On Cleaning the Glasses.—" When you clean the eye-
glasses (a point of great  importance to pure vision),  do not
remove more than one at  a time, and be sure to replace it be-
fore  you begin another; by this means you will be  sure to
preserve  the component glasses in their proper places; recol-
lect  that if they become  intermingled, they will be  useless.
Keep a piece  of well-dusted chamois leather, slightly impreg-
nated with some of the finest putty or crocus powder, in a little
box  to wipe them 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, endeavor 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 Microscopes.—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 cover the
parts while hot with a  black lacquer, made by mixing lamp- 
   miscellaneous hints to microscopists.  197

 black in a solution of shell-lac in strong spirits of wine.  A
 more elegant method, 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 plati-
 num) ; after remaining on the work a few minutes it is wiped off,
 the surface having assumed a deep brown or black color.  If
 these are not at hand, a strong solution of muriate of ammonia
 will answer  for temporary purposes.   Another method of sti-
 fling false light is by stops or diaphragms in the body of the in-
 strument ; these have already been referred to.
   Cabinet for Microscopic Objects.—The author of " Mi-
 croscopic Objects" recommends a cabinet with shallow drawers
 —twelve of  them  occupy a depth of four and a half inches—
 the 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 slides  meeting in the  middle of  the
 drawer are kept down by a  very thin slip  of wood covered with
 velvet.   In this way the slides 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  selec-
 tion.
   Some persons have their slides arranged edgewise, in  boxes
 made in imitation of books; the ends of the slides being held
 by a sort of rack.  This sometimes may be convenient, but  the
 other form is preferable.
   Goadby's Manipulating Box.—This is an exceedingly
 neat and useful article, represented by  Fig.  63.  No. 1, repre-
 sents  the box when open,  No.  2, a movable tray of peculiar
 form,  and No. 3, the box with  No. 2 removed.
   " No. 1.—a. Compartment to receive a bottle, 2 inches square,
3 \ high, to the top of the stopper, for  preserving  fluid.—b.
                          17* 
198
THE  MICROSCOPIST.
Space reserved for the spirit lamp.—c, c. A shelf of tin, perforat-
ed with six holes, to receive three stoppered, two-drachm bottles,
for liq. potassse, sulphuric acid, camphene (or turpentine), and

                           Fig. 63.
three glass jars, 2fths high, Iths diameter, made out of stout
glass, without a lip, and fitted with corks, for Canada balsam,
prepared asphaltum, lamp-black  and gold size.—d. A  slab of
porcelain, 2|ths square, resting upon a tin frame, and carried up
so as to be flush with the level of all the bottles, and the tray
(2),  when in its place.  Beneath the slab is e, a drawer, 2|ths
long, 2£ wide, and f ths deep, to  hold about three dozen of the
smallest slides I use, viz., 2£th by f ths.   Beneath  e is a deep
well, which occupies the space  from the drawer e to/, another
drawer, which runs the whole length of the box, from front to
back; it has the width and depth of e.
   No. 2.—gx. This compartment of the tray measures 8  inches
long, 2£ full wide,  1J deep.  It contains the iron plate, its
brass legs, and mahogany stand; a small cutting-board, kept for
thin  glass  only, measuring  6 inches by 2f ths, ith  thick, fur- 
   miscellaneous  hints to microscopists.  199

nished with a guide-board 5 inches long, % inch wide, and ith
thick, and a gauge, 6 inches  long, nearly f ths wide, and ith
thick.   A card-board box, 2 J by If ths, and iths deep, to hold
plates of thin glass; the small  brass square, already described;
mahogany square,  6  inches by 2J, ith  thick;  a  number  of
badger's-hair pencils in handles.—g2. Glazier's diamond; scratch
do.; marine  glue (cane)  brush;  knife and engraver's tool for
cleaning cells; small glass mules to grind the black cement on
the porcelain  slab,  and sundry  glass (dropping  and  other)
tubes.—g3. Pill-box with whiting; white wax for thread;  cot-
ton-wool; sundries.
   No.  3.—h. A fixed tray, 4  inches by 2 J, and fths deep, to
contain glass for covers to larger cells.—i. A well,  5 £ by 4
inches,  1? full deep, to hold  spare slides of the larger size,
with or without cells cemented to them, spare  cells, &c.—k.
A supply of the finest and other varieties of China three twist;
pill-box containing small pins,  so necessary in dissecting; pill-
box containing cells cut in the thinnest glass.—Drawer/, con-
tains several small palette-knives, in ivory handles, for mixing
the cement on the slab; the blades differ in length from 1J to
3ith, and from ith to fths at the point; drills for glass and
many little things.   Below the shelf c c, is a similarly perfo-
rated shelf, raised somewhat from the bottom,  the design being
to grasp the bottles at two points.   Should the  bottles  not be
sufficiently high to occupy all the depth allowed for them, they
must be raised by a shelf of tin, the intention being, that when
the box is closed, everything  should  be  more or less pressed
upon and kept in its place. The whole is japanned dead black
within, and lustrous black without."
  Brewster's Method  op Illuminating  Objects.—Con-
sidering  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 illumi- 
200
the  microscopist.
nating 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
disk 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 aberra-
tion, 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 reach the object, or after they have passed it.
  Mode of Obtaining the Wheel Animalcule (Vorti-
cella rotatoria).—" Early in the spring I fill  a three-gallon jug
with pure rain-water (not butt-water, because it contains  the
larvae of the great tribe).   This quantity more 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 same quantity of green sage  leaves,  also
tied and trimmed.  About every ten days I  remove the decay-
ed 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 (including the dirt which adheres to  them by the
tail), or under the hay or sage."—J. Ford.
   Substitute for the Concave Speculum.—Mr. G. Jack-
son employs a plano-convex lens  of about  two inches in diame- 
   miscellaneous hints to microscopists.  201

 ter, and of four and a half inches focus, silvered on the plane
 slide,  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 desir-
 ed for throwing light upon an object viewed as opaque.   We
 have used such arrangement for some time in place of the con-
 cave mirror, and deemed it peculiar to ourselves till reading an
 account of the above.
   Apparatus to Prevent ojjpe Evaporation op Liquids
 under the  Microscope.—Vapors  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 com-
 pletely 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  en-
 closing 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.—Raspail's  Organic
 Chemistry.
   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  animal-
culae may  also be made in the same way. 
 
INDEX.
Achromatic object-glasses, their invention an epoch in histology,
                         description of,
                         comparison of different makers,
Animal tissues, to be examined when fresh,
               on procuring,
Accessory instruments,  .
Animalcule cage,
Asphaltum cement,
Agate,      ....
Aphides,     ....
Acari,   .      .       .  '
Anatomical preparations,
Areolar tissue,
Artificial star, as a test object,
Angle of aperture, explained,
Arm rests,    ....
Albuminous urine,
Alkaline salts in urine,
Advantage of polarized light in examination,
Apparatus to prevent evaporation,  .
    FAQ I
      18
      34
      38
      17
      81
      41
  37,  49
      60
      67
      77
      90
      90
      94
    103
    111
    112
    120
170, 183
    173
 .   193
    201
                               B.
Bog iron ore, from infusoria,
Borelli, his observations on pus, &c,
Blood corpuscles,
14
15
95 
204
INDEX.
Blood disks of siren, .
Bone,    .
Basement membrane,
Bat's hair,       .
Branchial cartilage of tadpole,
Blood in urine,   .
Bile in urine,
Brewster's mode of illuminating objects,
    PAGE
     95
     97
104, 131
 .   114
    135
169, 181
    182
 .   199
Causes of error in observation,
Coal beds, from vegetation,
Coddington lens,    ....
Compound microscope,  .
                     defects of the common,
                     improvements in the,
                     mechanical conveniences necessary to the
                     forms of the,
                     most celebrated makers of the,
                     Smith and Beck's,
                     efforts to reduce the price of the,
Condenser,
          for oblique illumination,
Condensing (or bull's eye) lens, .
Camera lucida,
Compressorium, .
Cook's preserving fluid,
Cooper's preserving fluid,
Cells for mounting,   .
Cements, ....
Canada balsam cement,
Charring vegetable matters,
Carbonate of lime,   .
Crystallization of salts,  .
                 water,
Cuticles, .
Cellular tissues,     .       ,
   15
   14
   29
   31
   33
   33
   35
   36
36, 38
   36
   38
41, 53
   42
44, 52
37, 47
   50
   56
   56
   59
   60
   61
   61
   67
   67
   68
   69
   70 
INDEX.
205
	PAOB
Charcoal, .....	73
Circulation in vegetables, ....	78
Corals, ......	86
Circulation of blood, ....	96
Capillaries, their functions,	. 106
of skin, . . . . .	. 100, 109
of mucous membrane,	. 105, 109, 167
Crystalline lens in fish, ....	101
Ciliary processes of the eye,	. 101
movement, .....	105
Chromatic aberration, ....	33
mode of observing, .	110
Circulatory system of insects, .	. 126
Chemical constitution of organized bodies, .	130
Cell-growth in a meliceritous tumor,	. 137
Classification of animal tissues,	136
malignant growths,	. 142
Carcinoma, ......	143
Chemico-gelatinous injection by Dr. Goadby, .	. 164
Cystine in urine, .....	179
Colors exhibited by polarized light,	. 192
Cleaning the glasses of microscopes,	196
Cabinet for microscopic objects,.	. 197
                                D.

Dissecting microscope of Mr. Slack,
Dark wells,
Diaphragm,  .
Deut-ioduret of mercury,
Dissecting needles,   .
          troughs,
Digestive system of insects,  .
Development of cells,
               animal tissues,
Diabetic urine,  .
                                18
. . .		38
37,	41, I	51,53 68 119 120 125 131 134 70 185
 
206
INDEX.
                               E.

Erector,      .....
Entozoon folliculorum,  ....
Epithelium,   .....
Examination of morbid structure,
                               its importance,
Encephaloid,    .....
Earthy phosphates in urine,
Eyes of animals, .....

                               F.
Fossil remains determined by the microscope,
Fontana, histological observations of,
Frog plate,   .....
Fishing tubes,   .....
Fossil wood,  .....
Ferns,    ......
Fibrous and areolar tissue, .
Forms of nuclei, .....
Form of fibrous tumor,

                               G.
Geology, use of microscope in,  .
Goadby's fluids,      ....
         manipulating box,
Gum mastich cement,
Glycerine,       .....

                               H.

Histology, created by the microscope,
Hewson on the blood globules,  .
Herschell's doublets,
Holland's triplet,       ....
Huygenian eye-piece,
Hairs, down, &c, of plants, 
INDEX.
Hard tissues,
Hair of animals, .
Horn, hoofs, quills, &c,
Human blood,
Hair of Dermestes,  .
Hippuric acid,  .
 Importance of the microscope to zoology,
 Inorganic objects,
 Illuminating lamp,  .
 Iron pyrites,
 Infusoria, classification of,
          on procuring,
          to observe the structure of,
          fossil,  .
 Insects, antennaj of, .
        eggs,
        elytra,
        eyes,
        feet,
        hairs,
        mouths,  &c,
        parasitic,
        trachea,
        stings, ovipositors, &c,
        internal  anatomy of,
 Injected papillae of skin,
        preparations,
 Instruments for minute dissection,
 Internal anatomy of insects,
Injecting materials,
 Instrument for diagnosis of tumors,
Injection of the lymphatics,
Japanner's gold size, 
208
INDEX.
K.
Kiestein, .
PAGE
170
                               L.
Lenses, different forms and effects of,
        simple mode of making,
        imperfections in,
Lewenhoeck, his discoveries,
Lieberkuhn, his anatomical researches,
            concave reflector, so called
Lamp-black cement, .      .       .
Lichens and fungi,
Loaded corks,
Lepisma saccharina,
 22
 28
 29
 16
 17
 46
 61
 77
120
115
                               M.
Malpighi, microscopic researches of,                           [ 15
Modern observers,      .      .      .      .       .       .19
Medico-legal inquiries with the microscope,       .       .        21
Micrometer eye-piece,   .       .       .      .      .       .35
            stage,  ......        48
Magnifying powers, hints respecting,   .      .      .       .51
                   table  of,      ...       .        23
                   to obtain the power of a compound micro-
                     scope,   .       .      .      .       .48
Mirror, use of the,  ......        52
Management of the light,       .....    52
Mounting transparent objects,     ....        55
                            in the dry way,  .       .     55, 56,  63
                            in fluid,     ...        58
                            in balsam,      .      .       .61
Marine glue,.......        60
Mounting cellular structures,   .       ....    62
          opaque objects,   .....        64
          crystals for polarized light,   .      .      .       66, 194
Mosses,     .......        76 
INDEX.
 Muscular fibre,  ....
 Mucous membrane,  ....
 Mouse hair,      ....
 Morpho Menelaus,  ....
 Muscular system of insects,
 Morphology of pathological fluids,  .
 Method of injection, by Ruysch,
                      Rauby,
                      Monro, .
                      Professor Breschet,
                      M. Doyere,
                      Dr. Goddard,
 Mucus in urine, ....

                                N.
 Nervous structure, examination of, .
 Nerves  and capillaries of muscle,
 Nervous system of insects, .

                                0.
 Organic remains in limestone,  .
 Optical illusion to be guarded against,
 Opaque objects, mounting of,
               how viewed,
               Mr. Brooke's mode of viewing,
 Oolites,      .....
 Organic fibres,   ....
 Oxalate of lime in urine,

                               P.
Polarizing apparatus,   .
Preparation of glass slides, .
Preserving fluids,
Pollen,      .....
Pigment cells of skin,   .
        of the eye, .... 
210
INDEX.
Pontia brassica, .....
Podura plumbea,    ....
Proximate principles,   ....
Primary form of organic matter,
Pus in urine,    .....
    distinction between it and mucus,
Polarization of light,    ....

                               Q.
Qualifications of a microscopist,

                               R.
Religious sentiment, microscope conducive to, .
Reflecting microscope superseded,  .
          a curious form of,    .
Rules for microscopic observations,
Raphides,       .....
Retina of the eye,   ....
Respiratory system of insects,  .

                               S.
Simple microscopes, construction of,
                    magnifying powers of,
                    mode of mounting,
                    form of, for opaque objects,
Stanhope lens,      ....
Silver cup or Lieberkuhn,
Side reflector,       ....
Stage micrometer,      ....
Size of glass for mounting,  .
Sealing-wax varnish,   ....
Sand,        .
Sections of granite, &c,
           coal,     ....
           wood,       ....
Siliceous cuticles,   .... 
INDEX.
211
Starch,
Seeds,
Shells of mollusca,  .
Scales offish,
Skin, .
Spherical aberration,
Scales of insects,
Shells of infusoria,
Swammerdam's scissors,
               mode of dissection,
Secondary organic compounds,
Scrofulous growths,
Syringe for minute injection,
Stopping false light in microscopes,
Substitute for the  concave speculum
                                T.
Trough for chara, &c ,  .
Thin cells for delicate tissues,
Teeth,   .....
Theory of life and sensation,
Test objects, Dr. Goring's discovery of,
            character of,   .
Tinea vestianella,
Tables for examination of urinary deposits,
       of results of Dr. Gruby's observations,
                                U.
Utility of the microscope in medicine,
Urinary deposits,
Urea,        ....
Uric acid,
Urate of ammonia,
         soda,
1G9,
 19
169
171
171
180
180 
212
INDEX.
                                V.

Vegetable physiology, microscope indispensable in,
Varley's dark chamber, ....
Vegetable tissues, dissection of,    .
Vascular tissue in plants,
Vitality and electricity not identical,
Valentin's knife,  .....
Vital principle, theories respecting the,

                                W.
Withering's Botanical Microscope,
Wilson's Pocket Microscope,
Wollaston's doublet,    ....
           condenser,      .
Watch-glasses useful,   ....
White fibrous tissue,         .
Wheel animalculae, mode of obtaining,  .

                                 Y.
Yellow fibrous tissue,                     .

                                 Z.
Zoophytes,       .....
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MORFIPS   CHEMICAl7aNDThARM/EGEU-

               TICAL  MANIPULATIONS,
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 A  MANUAL  OF  THE MECHANICAL  AND  CHEMICO-MECHANICAL
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         ASSISTED  BY  ALEXANDER  MUCKLE,
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                     IN ONE VOLUME,  OCTAVO.

      Extract of a Letter from Prof. J. C. Booth, Practical and Analytical Chemist.
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experimental or manufacturing chemist; for, while the business of the former is wholly
experimental research, the latter is frequently forced to enter into the same field, in order
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vain in any of the professed treatises on Chemistry.  The author has had in his mind the
admirable treatise of Professor Farraday, and has given in a condensed form nearly all
that is valuable for ordinary use in that work, besides much original matter, and  much
collected from other sources—all of which has been rendered far more useful and intelli-
gible by the aid of excellent illustrations— American Journal of Pharmacy.

  To every one who desires to become familiar with the operations of the  laboratory, a"
«vith those of physical science in general, we recommend this work, as it will be founi
upon trial to recommend itself strongly. It contains descriptions of the newest apparatus
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               HAVE FOB SALE A VERY LARGE ASSORTMENT OF

      COMPOUND   MICROSCOPES.


Neatly mounted 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 fifty times.   Price,                 $16 00
Ditto, with power of 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, con-
  denser, 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, $33 00 to $37 00
The  very best Achromatic  Microscopes, with movable lever or
  rack-work stage—Microscope to be placed  either vertical or
  horizontal—bull's  eye condenser—frog-plate,  &c.;  cost from
                                                    $150 to $650
Sets  of Achromatic Lenses, of various powers, separate from the
  Microscopes,                             $4 50 to $9  00 per set.
Eye-pieces, of various powers, separate from the Microscopes,
                                             $2 25 to $3 00 each.
Glass slips for Microscopic slides  or preparations,     50 cts per doz.
Glass dishes and covers for Microscopic slides, and wet prepara-
  tions,                                    $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 in-
  sects,  sections of wood, guano,  feathers, &c.  Prices from
                                              $2 to $6 50 the set.
Finely prepared objects, parts of insects, &c,    19 to 50  cents each.
  "       "      "    anatomical as injections,      75  cents each.

  Also,  Magnifying Glasses, in horn cases, for the pocket;  Micro-
scopes to examine the ear; Urinometers, Thermometers, Hydrometers,
Weighing Scales, Magnets,  Mathematical Instruments, Spy-Glasses;
Camera  Lucidas, Stanhope Lenses, &c. 
 
 
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