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THE    MICROSCOPIST. 
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USE OE  THE MICROSCOPE
PHYSICIANS, STUDENTS,
LOVERS OF NATURAL SCIENCE.
WITH ILLUSTRATIONS.
          BY

    JOSEPH H-QJP^ES, M.D.



      PHILADELPHIA:
LINDSAY AND BLAKISTON.
          1851. 
OH





 : 6 G'l
           Entered, according to Act of Congress, in the year 1851,




                    BY LINDSAY AND BLAKISTON,




In the Clerk's Office of the District Court for the Eastern District of Pennsylvania.
C. SHERMAN, PRINTER. 
TO
     PAUL BECK GODDARD, M.D.,






              DISTINGUISHED BY






HIS  ARDENT AND SUCCESSFUL PROSECUTION




                 OF




         THIS AND KINDRED STUDIES,













      IS  RESPECTFULLY INSCRIBED




                 BY





            THE AUTH01'.. 
 
PREFACE.
  Since the employment of achromatic instruments, mi-
croscopic  research has ceased to be merely an amuse-
ment, but has been elevated to the dignity of a science;
yet, so far as the author knows, no book has been issued
from the American press  which Avould  senre  as a guide
to those desirous of applying themselves to such studies.
  The present work  aims  to supply this deficiency.  In
its preparation the  author has aimed less at style than
at information.  Its  matter has been condensed into the
smallest possible space, so that it may be, what its title
professes, "A Complete Manual on the Use of the Micro-
scope."  It does not  supersede  the necessity of more
elaborate  works, especially in the  departments of Minute
Anatomy and Pathology,  but gives directions by which
such works may be more profitably employed by the stu-
dent.   The multiplied labours of many observers have
been classified and arranged, and  free use has been made 
X
PREFACE.
of English authorities, so as to bring the work up to the
present standard of information;  at the same  time the
opinions and experience of the author have been stated
without hesitation.
  Respecting  the  construction of the  Microscope itself,
a brief description  is all that was deemed necessary; nor
could it have  been much more  extended without being
liable to serious objection.   As to the employment of
the instrument upon the  various objects of science, as
full an  account has been given as was  consistent  with
brevity; and to make this department more complete,
reference has been made to the doctrines and discoveries
of modern Physiology and Pathology.
  The work is committed  to the notice of the  scientific
community with the hope that  it may prove of service in
the study of the wonderful works of the Great Creator,
who is "all in all, and all in every  part;" whose Power
and Wisdom are seen as well in the minutest atom as in
the most gigantic  masses; and whose government  em-
braces not only intelligent free  agents,  but  also the
smallest animalculse existing in a drop of stagnant Avater. 
CONTENTS.
Chapter I.  The History and Importance of Microscopic
            Investigation,      .      •       ■      .13
       II.  The Microscope,   .                          22
       III.  Adjuncts to the Microscope,       .      .    40
       IV.  How to Use the Microscope,     .      •       49
       V.  On Mounting and  Preserving  Objects for
            Examination,       .      •       •      .53
       VI.  On Procuring Objects for the Microscope,      64
      VII.  Test Objects,  .      .      •      •      .98
     VIII.  On Dissecting Objects for the Microscope,    105
       IX.  The Cell-Doctrine of Physiology,  .      -   114
       X.  Examination of Morbid  Structures, etc.,      124
       XI.  On Minute Injections,       •      •       •   134
      XII.  Examination of Urinary Deposits,     .       143
     XIII.  On Polarized Light,  .       •      •       .162
     XIV.  Miscellaneous Hints to Microscopists, .      170 
 
THE   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 G-od 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!"
  To the geologist, it reveals the striking,  yet humbling fact,
that the world on which we tread is but the wreck of ancient
                            2 
14
THE  MICROSCOPIST.
organic creations.  The large coal beds  are  the ruins of a
luxuriant and  gigantic  vegetation;  and  the  vast limestone
rocks, which are so abundant on the earth's surface, are the
catacombs  of myriads of animal tribes which  are too  minute
to be perceived by the unassisted vision.  It exhibits, also,
that metallic ore, as the Bog  Iron Ore, and immense layers of
earthy and rocky matter, are formed merely by the aggregation
of the skeletons or shields of Infusoria;  while  beds of coral
rocks are still in the process of  formation, the architects being
tiny marine polypi.  Further, by this instrument, the nature
of gigantic fossil remains  is often  determined, and by it they
are  assigned  their true  place  in the  classification  of the
naturalist.
   To the student of vegetable physiology, the microscope is an
indispensable  instrument.   By it he is enabled to trace  the
first beginnings of  vegetable life, and the  functions of  the 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 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 physi-
ology, or  pathology, are indispensable  to the student or phy-
sician 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 io-rojr, a tissue or web, and
 Xoyof, a discourse. 
HISTORICAL INVESTIGATION.          15
  The attempts made  by the early microscopic observers to
determine ultimate structure, were  in general of little value,
partly on account of the imperfections in the instruments 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 Avas  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 animalculse existing in
the animal tissues  and  fluids.   An examination  of abnormal
fluids with the microscope favoured this idea, as the globules
were immediately taken for  living  beings.  Borelli described
the pus globules as animalcules, and even says he has seen  them
delivering their  eggs.   It will  be  seen that this was a very
natural mistake, when we remember that these globules contain
several minute granules, which make  their escape when the
external envelope  is  broken or dissolved.   In this  way we
often  find the germs of truth  in the curious speculations of
the early microscopists.
   Malpighi was the* first to witness the most beautiful  sight
which the microscope can reveal,—the actual circulation of the
blood, thereby demonstrating the reasoning  of Harvey to be
true.  The first work  he  published, in 1661, comprises his
microscopic observations relative to the  structure of the lungs.
Between this  period and 1665, he published other tracts on 
16
THE  MICROSCOPIST.
the minute anatomy of the kidneys, spleen, liver, membranes
of the brain, &c, and  several of the structures still  retain his
name.  He also paid attention to the anatomy and transforma-
tions of insects,  the development of the chick in the egg,  and
the structure of plants.  It  will be perceived from the  last
remark, that the intimate connexion between animal and vege-
table physiology was even then acknowledged.  This connexion
has led to the establishment of the cell doctrine, or  the theory
of the development of all organized tissues from cells.
   Lewenhoeck has sometimes been called the father of 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 im-
provements 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 medi-
cine, 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  mus-
cles, the crystalline lens, the milk, and numerous other textures
and fluids; and  made the interesting discovery  of the sperma-
tozoa, which he  conceived to be of different sexes.   There can
be no doubt that he made numerous errors, but the  whole  sub-
ject being new, his errors were excusable; and his contributions
to science are still of  the highest interest.
   Swammerdam,  Lyonet, and Ellis, after this  period, greatly
extended our knowledge of the lower tribes of animals; while 
HISTORICAL INVESTIGATION.         17
Lieberkuhn, Fontana, and Hewson laboured successfully in the
department of histology.
   To Lieberkuhn we owe the first good account of the anatomy
of the villi, and of the minute  tubular glands of  the small
intestine, which still bear his name.   As a minute injector he
has never been surpassed.
   Fontana examined the brain, nerves, muscles, and several
other textures, with great care, and his observations were 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
resulted.  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
he saw the same fibres  and always mistook them for nerves.
The  fact was, that  he made his  observations while the  direct
rays of  the sun  were transmitted through the substance  under
examination, and the optical  phenomena which were  produced
led to the mistake.   He afterwards found them on the surface
of metals, and then frankly acknowledged his error.
  Another source of early errors was the treatment to which
their preparations were  subjected before examination.  It is
now  well known that animal tissue should be examined while
fresh and transparent.  What result is it possible to draw from
                            2* 
18
THE  MICROSCOPIST.
the observations of those who  boil, roast, macerate, putrefy,
triturate, and otherwise  injure the delicate tissues ?   Most of
the tissues contain albumen,  which, so treated, gives origin to
globules, and flakes of different forms;  a circumstance which
has led several anatomists  to conceive  the  basis of  animal
structures  to be  globular.   Several  late observers have also
made this mistake.
   Messrs. Todd and  Bowman, the learned authors of " The
Physiological Anatomy and Physiology of Man," present the
following sensible remarks respecting this subject,—"To make
microscopical observation really beneficial  to  physiological
science, it should be done by those who possess two requisites:
an eye, which  practice has  rendered familiar with genuine
appearances as contrasted with those produced by the various
aberrations to which  the rays of light are liable in their pas-
sage 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 favour of certain theories, or strained analogies.
The history of science affords but  too many  instances of the
baneful influence of the idol a 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, Muller, 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  Royal College of Surgeons, England),  on  microscopic
science, have done  much to increase  a desire  on the part of
medical students and others to  become practically acquainted
with this subject.   His lectures to the students of the 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 Schbnlein 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 tumours, &c, all exhibit the value
of this instrument to medical science.
   In medico-legal researches the microscope has already proved
a valuable auxiliary.  It has several  times been employed to
ascertain the true nature of spots  suspected to be blood-stains,
&c.; and in  cases where human life was suspended upon its
decision.
   In 1837, M. Ollivier  was directed to ascertain whether any
human hair was attached to the blade of  a  hatchet seized in
the  house of a person suspected of murder, and  if this were
the  case, to determine the colour of the hair.  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—i inch, 20  diameters—i inch, 40  diameters—ith
inch, 80 diameters—y^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, I, 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, b, which forms the stage  for carrying
the objects, is made to slide up and down on these wires.  The
upper plate, a, carries the lenses, i, and the lower one, c, 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- 
26
THE  MICROSCOPIST.
densing glass.  It was afterwards improved by the addition of
a handle placed at right angles to its body.
  The best form of the simple microscope for viewing opaque
Fig. 4.
objects, is that represented by Fig. 4 :  a is a flat piece of brass
attached to the handle, p; it supports the  lens-holder, i, and
through it passes the screw, b, which is connected to the 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, k, 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 turn-
ing the nut d.
   For  minute dissection of animal or  other tissues, which is
generally performed  under water, as hereafter described, the

                            Fig. 5.
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  attached to the tin  box, C, which is de-
signed 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 com-
mon lenses; arising either from the shape  of the lens,  or
from the nature of light itself when passing through a refract-
ing medium.   These  imperfections  are termed respectively,
spherical and chromatic aberrations. To lessen or destroy these
aberrations  various  plans  have  been proposed, with various
success.  Mr. Coddington proposed a lens in  the form  of a
sphere, cut  away round the centre, as at A, Fig. 6.   This is
an excellent form for a hand lens, but is not often to be pro-
cured in this country;  opticians preferring to  dispose of the


                            Fig. 6.
Stanhope lens, seen at B, which is more easily made than the
Coddington lens, but is inferior to it.   C and D are doublets
proposed by Sir John 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. Wollaston'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  dis-
tance  is about the difference of their focal lengths.  Between
them  is a  diaphragm or  stop, generally placed immediately

                           Fig. 7.
behind the anterior lens.  The stop was not employed by Dr.
Wollaston, as his  lenses were  of such  high power that they 
THE  MICROSCOPE.
31
nearly touched each other;  yet it is, nevertheless, found to be
essential to a good doublet.
   A, C, Fig. 7, represent the  lenses of the doublet, and B is
the  diaphragm  or stop.  The manner  in  which the light is
refracted by this instrument, is shown by the lines proceeding
from each end of the object, 0.   The  dotted lines  represent
the blue or most refrangible rays of the spectrum;  the others
are the red rays.   Those rays which pass through  the centre
of the lens, A, are caused to pass through the hole in the 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 colour round the edge  of
the field of view, and also  similar colours around the edges of
the object he is viewing.  These defects arise from the decom-
position of  common  white light; and are  called chromatic
aberration or dispersion.  The  colours round the field of view
are produced by the defects of the eye-piece;  and those round
the  object,  by  the object-glass.   Again:  if the  object  be
looked at through the instrument  as  before, its outline  or
 edges will be observed, not sharp and distinct, but thick and
 confused.   This is caused by the rays not  being collected into
 a perfect point  as they  were on the  object itself.   This  defect
 is called  spherical aberration.   When  an  instrument  has
 neither its chromatic nor  spherical aberration removed, it is
 said to be uncorrected.
   To conceal these defects there is generally a small hole or
 stop  behind the object-glass.   This is  injurious to correct
 vision, as it prevents a large portion of light  from entering the
 eye, and  makes the  objects appear dark, so that their true
 structure  cannot be  made out.   When this is  the  case, the
 instrument  is said to want angular  aperture.  The stop 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 colour, 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
B
  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.
   A variety of forms have been given to the mechanism of the
35408�79�53���561424712�13067999 
36                THE  MICROSCOPIST.
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 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 frontispiece.
  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
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-piece, 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, j, when a  glass trough,  u, is used.  A profile of the
glass trough, with its diagonal plate of glass for confining an
object, is seen at u'.  At z, is a three-pronged forceps.
  A large  double mirror, k, concave on one side and plane on 
THE  MICROSCOPE.
37
the other, is supported by the cylindrical bar, 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
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. 8 and No. 4
 have the tube of their front  lens movable for adjusting their
 performance with objects either uncovered or covered with thin
 glass.  The graduated screw collar, by which  the adjustment is
 made, is seen at 5.
   The high price of these  instruments must necessarily put
                              4 
38
THE  MICROSCOPIST.
them out of the reach of those whose  means are limited, and
our opticians seldom  import  them, except  to order.   Of late,
however, a praiseworthy effort  has been made  to simplify the
construction of the mechanical parts, so as to bring the price
within the  control of  the generality of medical  men  and other
students of nature.   Mr. J. B. Dancer, Manchester, England,
furnishes a very complete  microscope,  with two object-glasses
and  the necessary apparatus, for  £10.  Messrs.  Powell and
Lealand have also fitted up an instrument with  a stand of 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 construction of most  of those  used  or
exposed for sale, is far inferior  to the English.  Hitherto, also,
the fashion in  this country in  regard  to microscopes,  has led
to the almost universal employment  of high  powers, to the
neglect of the  others, so that it is  exceedingly  difficult to pro-
cure an achromatic object-glass with  shallow magnifiers, not-
withstanding the decided  advantage to be derived from their
use.

             REFLECTING MICROSCOPES,

  In which the image was formed  by a concave mirror instead
of a lens, are not  now so much used as formerly.  They are
generally  complicated in  structure,  and  are  surpassed and
therefore superseded by the achromatic microscope.
  The following is a simple reflecting microscope, invented by
Mr. S. Gray, and may be of some interest from  its singularity.
  A, Fig. 11,  represents a brass ring, one-thirtieth of  an inch
thick,  whose inner diameter is about two-fifths  of an  inch. 
THE  MICROSCOPE.
39
Having dissolved a globule of quicksilver in one part nitric
acid and ten parts water, he rubbed with it the inner surface
Fig. 11.
of the ring, which became silvered;  having wiped it dry, he
put a drop of quicksilver within it, which, when pressed with
the finger, adhered to the ring, and formed a convex speculum.
When the ring was taken up carefully, and laid on the margin
of the cylinder,  B, the mercury sank  down,  and formed a
concave reflecting speculum.   The cylinder, B, is supported by
a pillar, which is attached to the foot,  D.  The stage, G, is
for holding the object, and is adjusted to the focus by the screw
at C. 
CHAPTER  III.
           ADJUNCTS  TO  THE  MICROSCOPE.

  In addition  to  the mirror, object-glasses, eye-glasses,  and
the parts constituting the stand of a microscope, several 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.
  The 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.
   The Condenser.—This  is an arrangement  under the  stage 
ADJUNCTS  TO THE MICROSCOPE.        41
for condensing the light upon the object.  The best instruments
employ an arrangement of achromatic glasses, similar to  the
object-glasses, but its value is scarcely equal to its cost.  The
Wollaston Condenser is a short tube, in which a plano-convex
lens of three-fourths of  an inch focal length, with its flat side
towards the object, is made to slide up and down. Dr. 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.
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.
   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.
                             4* 
42
THE  MICROSCOPIST.
  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

                          Fig. 14.
the end of the eye-piece towards the object-glass.   It  is only
used when it is  desired to dissect with the compound 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.        43
which turns upon its axis, and slides up and down a stout wire
affixed to a steady foot.   B, is the smaller lens, whose handle

                           Fig. 15.
slides through a socket, working on a hinge joint.  Sometimes
a lens of this  kind is  affixed to the stage of the microscope.
C, is the object upon which the light is concentrated.  D, the
lamp.  To condense the light on the mirror, the lens, A, alone
is used.  The lamp is of  the kind called a fountain lamp, and
slides up and  down a stem, on which it  can be fixed at any
height by the screw F.  E represents a section of a shade,
which should always be used with the lamp. As it is a matter 
44
THE  MICROSCOPIST.
of much consequence to our observations that we should have
a steady, intense light, it is not immaterial what kind of oil,
&c, we employ.  After many trials and disappointments, I am
convinced that pure sperm oil is the pleasantest,  cheapest, and
best.
  Lieberkuhn, or Silver Cup.—This is a most useful 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, /.  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. 
          ADJUNCTS TO  THE MICROSCOPE.        45

  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 ith and y'jth
inch object-glasses).   This  is performed by  two reflections.
The rays from a lamp, rendered parallel by a condensing lens,
are received on an elliptic reflector, the end of which is cut off
a little  beyond the focus;  the rays of light converging from
this surface are reflected down on the object by a plain mirror
attached to the object-glass, and  on a level with the outer sur-
face.   By these means the structure of the scale of the podura,
and the different characters of the inner and outer surfaces, are
rendered  distinctly visible."  I have not had an opportunity
of  testing this plan, but have little doubt of its success.
    Camera Lucida.—By which  drawings are  made from the
microscope.  This is generally formed by placing a small prism
of  glass, inclined at the proper angle, in front of the eye-piece.
In Fig. 17, a, represents the camera, formed of highly-polished

                           Fig. 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. 
46
THE  MICROSCOPIST.
  Frog-plate; Fig. 18; on which frogs or fish are tied to ex-
amine the circulation of blood in their vessels.   The frog, &c,


                         Fig. 18.
                       o         o


                       •O
                       c         °
                       c         o
                       o         0

                       °         c
                       O        o
                       O         0

                      w

must first be  enclosed in a bag, and fastened on the plate  by
the holes in either side of it.  Then  thread  is tied to about
four of its toes, and the web is spread out over the large hole
by fastening the ends of  the thread through the smaller holes
in the plate.
   The Stage Micrometer consists of a  slip of glass, pearl, &c,
having a line  finely divided  into  parts of an inch, &c.   To
obtain with this the power of  a compound microscope, compare
the divisions seen with one eye through the  instrument, with
a rule held ten inches off, and looked at with the other eye.
Suppose, for instance, the micrometer be divided into youths
of an inch, and one of these  divisions covers an inch of the
rule seen  with the other eye, the magnifying power of the
instrument is  100  diameters.    If it should cover five  inches, 
ADJUNCTS TO  THE  MICROSCOPE.        47
it  is  magnified  500  diameters.  By sketching the object  by
means of the  camera, and then putting in  its place a stage
          Fig. 19.
ABC         D
Fig 20.
micrometer, and  marking the  divisions  over the sketch, they
can again be  subdivided, and  so  the measure of an object
be accurately taken. 
48
THE  MICROSCOPIST.
  Animalculee Cage is a round cell with a glass  bottom and
top, for confining a drop of water with animalculae.
   Watch- Glasses and Fishing Tubes, are useful adjuncts.  The
latter, Fig. 19, are glass tubes of various sizes, by which when
one end is closed with the finger a quantity of water, &c, may
be lifted from a phial, as seen at Fig. 20, and put in a 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.
                             5 
50
THE  MICROSCOPIST.
  2. Delicate observations should not be made when the fluid
which lubricates the cornea of the eye is in a viscid state.
  3. The best  position for microscopic  observations is when
the observer is  lying  horizontally on his  back.   This arises
from the perfect  stability of the head, and from the equality
of the lubricating film of  fluid which covers the cornea.   The
worst of all positions is that in which we look downwards 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 dimi-
nished,  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 
HOW TO  USE THE MICROSCOPE.        51
bull's-eye lens is not  used, the illuminating body should not
be more than  five or six inches from the mirror.  The latter
is seldom required  to  be more than  three  inches from the
object, the details of which are usually best  shown when the
rays from the mirror  fall upon  it before crossing, and the
centre  should  (especially by lamp-light) be in the  axis of the
microscope.   For obscure  objects, seen by transmitted light,
and for outline, a full  central illumination is commonly best;
but for seeing delicate lines, like those  on the scales of insects,
it should be made to fall obliquely, and in a direction at right
angles  to the lines to be viewed.
  " The  diaphragm is often of great use in modifying the light,
and stopping such rays as would confuse the image (especially
with low or moderate powers), but many cases occur when the
effects  desired are best produced by admitting the whole from
the mirror.
  " If an achromatic condenser is  employed instead of the 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." 
52
THE  MICROSCOPIST.
  The management of the light  with opaque  objects must
depend in a great degree  upon their  size, and  the  manner  in
which they are mounted.  If the object is small, and so 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.
  Next to the proper illumination of the object, the adjust-
ment of the focus is the most important thing to be  attended
to.   With a low power, the coarse  adjustment  is usually suffi-
cient 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.
                             5* 
54
THE  MICROSCOPIST.
  2dly. In some preservative fluid.
  3 dry. 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
coloured tissues, such as some of the smaller fungi, and found
that  salt and water, 5 grains to the ounce of  water, to which
acetic acid had been added, answered very well.   A few drops
of creosote or of camphor will prevent the growth of confervas.
  One part alcohol to 5 of distilled  water—1  ounce to 4  of
water—will preserve even very delicate colours.  This  is the
basis of the Gannal process for preserving animal  structures.
There is, however, the same objection to the use of this fluid
as to the salt and water.
  A weak solution of chromic acid is a good preserving fluid.
  Pure glycerine is prepared  by  the  London opticians as a
preservative fluid, and  is used in the proportion  of 1 part to 2
of water.  Its oily nature, however, often causes much diffi-
culty  in cementing the thin glass cover upon it. 
MOUNTING AND  PRESERVING OBJECTS.
55
  Dr. Goadby has devoted much attention to this subject, and
has succeeded in supplying to the microscopist a ready, cheap,
and effectual means for mounting animal structures with  the
greatest possible ease and  security.  Dr. G. received a gold
medal  from the  Society of Arts for his invention.   He  has
kindly  furnished me  with the  following  description of his
different preserving fluids.

                "A 1.  Bay salt (coarse sea-salt), 4 ounces,
                      Alum, 2 ounces,
                      Corrosive sublimate, 2 grains,
                      Boiling water, 1 quart.
                 " A 2.  Bay salt, 4 ounces,
                      Alum, 2 ounces,
                      Corrosive sublimate, 4 grains,
                      Boiling water, 2 quarts.

   " The A 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  1448,  which  is made by adding  more salt
  (about 2 ounces) to  the above.
    " The corrosive sublimate is used to prevent vegetation grow- 
56                THE MICROSCOPIST.
ing in the fluid, and  no greater  quantity should be used than
2 grains per quart of fluid; but, as it coagulates  albumen, it
must be left out when ova are to be preserved, or when it is
desired to maintain the transparency of certain tissues."
  A paragraph has recently been published in the  newspapers,
to the effect, that " a couple  of French savans  have simulta-
neously discovered that chloroform is an antiseptic of marvel-
lous virtue, preventing  animal  decomposition after death, or
promptly checking it if already  commenced.   All animal
tissues  when  subjected to its action become fixed for a long
period of time in the precise form and condition  in which they
may happen to be at the  moment of application, and natural
colours, even  to the  slightest and  most delicate  shades, are
preserved without  the slightest  change."   If this be so, the
desideratum in this respect will be supplied.   I have  not had
an  opportunity of testing it, but look  upon it as quite pro-
bable.*

  * Since the above was written, the following extract, confirming
the  alleged discovery,  appeared in the Medical Examiner:—"M.
Augend has communicated  to the French Academy of Sciences the
following experiments, which establish a marked line of demarcation
between ether and chloroform, and  point out in the latter a remark-
able property which has hitherto escaped the attention  of chemists.
  " If three wide-mouthed, ground-stoppered bottles are taken, and
into one we put  a few drops of ether, into another a few drops of
chloroform, and  leave  the third in statu quo; then place in each a
piece of beef, secure the stoppers, and leave them  during summer
weather, the following phenomena are observed:—The flesh, natural-
ly of a reddish-brown colour, passes at once to a vermilion-red, under
the  influence of the vapour  of chloroform  mixed with  air,  whilst it
undergoes no change in the  ether.   Such are the immediate effects,
but  at the end of a week the results are  still more distinct.  The
flesh preserved in the air has changed its colour slightly, that which
is preserved in the ether has become brown, whilst  that in the chlo-
roform has acquired the appearance of boiled meat.   On opening the
bottles, the meat  in the air has become offensively putrid, and the 
      MOUNTING  AND PRESERVING  OBJECTS.     57

  Mounting in Fluid.—The most minute structures, such as
the vessels of plants, and the muscular and other  tissues of
animals, requiring in all cases  high powers for their proper
exhibition, must of necessity be preserved in  very thin  cells
with a small amount of fluid.
  On a  slip of glass, 3 inches  by 1, cleaned  by a solution of
caustic  potash to remove all grease, lay a drop of  the fluid;
put the  object in this  and  spread it out with the point  of a
needle,  &c.  Select a thin and flat glass cover, clear  it likewise
from  grease,  &c, touch its  edges with cement,  and drop it
gently over the object.   Press it lightly, to exclude  the excess
of fluid, which 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

same  thing occurs in the presence of the ether, whilst  there  is no
change in the flesh kept in the chloroform,  apart from the sweet taste
and peculiar odour of the latter.
  " These antiseptic properties of chloroform have furnished interest-
ing results  to M. Augend.  He has found that 1-2000th part of it (?)
suffices to preserve a mass of  muscular  flesh.  Not less  remarkable
is the facility with  which the vapour permeates the densest tissues.
Chloroform has this advantage over creosote, that it does not coagu-
late  the albumen; nor  is it  on its part  decomposed by  muscular
 fibre.
   " The  most apparent action of the chloroform, not only on muscu-
lar substance, but also on the  fleshy pericarps of fruits and seeds, is
an immediate  contraction of the fibre or the parenchyma, which
causes the  watery juices to flow out on the bottom of the vessel in
which the experiment is made.—Gazette Medicate."
   From the foregoing account, it would  seem proper to expose  many
delicate  tissues to the vapour  of the chloroform before mounting in
balsam; or they may be preserved in the  chloroform itself, although
it would be diflicult, in such  case, to find a proper cement for the
 glass cover. 
58
THE  MICROSCOPIST.
best to make a thicker cell.  This may be made by painting a
round  or square ring on  the  slip with some sort of cement
which will not be acted  upon by the fluid employed.—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.
  Pieces of gutta  percha  tubes, cemented on to the slips by
heat, may sometimes be used for cells, and answer a good pur-
pose.   I have  made excellent cells by using narrow slips of
glass for the sides, cementing them with marine glue.   They
are square, and are well suited for the larger class of objects.

                        CEMENTS.

  Japanners' Gold-size, or Severe Dryer, is a mixture of boiled
linseed oil, dry red lead,  litharge, copperas, gum animi, and
turpentine.   The first and  last ingredients are its principal
constituents.   Mr. Williams, Artists'  Furnishing Store, Sixth
Street above Market, Philadelphia, has it for sale.
   Sealing-wax Varnish consists of small pieces of sealing-wax
dissolved in alcohol.
   Asphaltum,  dissolved in  turpentine, has this  advantage,
that spirit may be  employed as the preserving, fluid if desired.
   Marine Glue is a mixture  of shell-lac, caoutchouc, and naph- 
      MOUNTING AND PRESERVING OBJECTS.     59

tha.   It is melted by heat.   Caustic potash  will remove its
traces from glass.
  Gum 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.
  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.

                MOUNTING IN  BALSAM.

   Before objects are mounted in Canada balsam they should
be perfectly clean and free from moisture.   They are commonly
soaked in turpentine, especially opaque objects, as it renders
them more transparent.  Grease may be removed by sulphuric
ether.
   Very thin and transparent  objects become indistinct in 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.
 When objects of a cellular nature have to be  mounted, if they
 are such as heat will not much injure, they may be boiled in the 
60
THE  MICROSCOPIST.
balsam;  otherwise  numbers of air-bubbles will be left in  the
cells, and the true structure cannot then be made out satisfac-
torily.  The extra degree of heat  will  expand the  air and
cause it to escape, and the balsam will take its  place.
   Some  objects of a tubular nature, such as  the  tracheae of
insects, are better seen if air be contained in the tubes ; they
will then exhibit the spiral fibre in their interior; but a 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 flat piece  of iron, over a spirit-lamp; yet with careful
management a spirit-lamp will do alone.
   Some persons keep their balsam in a tin vessel that can be
warmed so as to melt it.   A drop of the fluid can then be
taken out and put on the object upon the slide.  This plan is
attended with  little  or no risk  of air-bubbles.   The  cover
should be warmed  on its under surface  before it is  laid on
the balsam, and if  necessary, a small amount of heat  applied
to the under side of the slide, to make the balsam flow more
readily.
   When animal structures, such as parts of insects, or  injec-
tions, have to be mounted, the heating of the balsam must be
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 
      MOUNTING AND PRESERVING OBJECTS.     61

in it  and covered in  the  usual way.   By pursuing this plan
(for which, with  many other suggestions, I  am  indebted  to
Mr. Quekett's admirable work on the Microscope), I have suc-
ceeded in making some excellent preparations at the expense of
but little time and trouble.
   If  the heat applied to the slide be great, the object will be
sure to curl up, and  bubbles will appear in all parts.   It will
most  likely be rendered useless, as no manipulation, however
carefully applied, will restore an overheated specimen of ani-
mal structure to its former beauty.

             MOUNTING  IN THE  DRY WAY.

   For objects which require a high magnifying power, they
may be placed on a slide and covered with thin glass, whose
edges may be touched with  cement.  Objects which  do  not
require an object-glass of short focus, may be placed between
two slips of glass whose edges have been levelled so as to form
a groove, which may be filled up with cement or sealing-wax.

             MOUNTING OPAQUE OBJECTS.

   These must necessarily be viewed by light reflected in some
manner from their surface..  Some transparent objects, however,
may  be viewed as opaque ones by using the dark well or stop,
e, Fig.  16.   When  mounted with  this  design  they may be
placed  on the slip of glass with a little gum-water, and 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.
   a, Fig. 21, represents a disc of leather, felt,  or other suitable
material, about three-eighths or half an inch in diameter, with a
                             6 
62
THE  MICROSCOPIST.
pin passing through it.  The side for holding the object is to be
blackened;  the other side is covered with white  paper  on
Fig. 21.
which the name is written,  b represents another plan, for very
minute  objects; the  pin is  encased with  blackened wax or
cement, or passes lengthwise  through a  small  cork cylinder.

                           Fig. 22.
Another method is seen at c, which consists of a small cylinder
of cork or felt with  a  pin passing transversely.   These  must
be blackened with common lacquer (shell-lac dissolved in alco- 
     MOUNTING  AND  PRESERVING  OBJECTS.     63

hol) and  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
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 colours, the worst which can be
employed, unless the object is totally black.


    MOUNTING CRYSTALS TOR 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, ^th
of an inch thick, exhibit a rich  motley colouring 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, 
PROCURING  OBJECTS.
65
solution of gelatine, &c, upon a  slide, put  into it a drop of
some strong solution of salts, as Epsom salts, hydrochlorate of
ammonia, tartaric acid, &c.   Hold the slide over the 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 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 J
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 of sand; 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 colour in this salt
 is a beautiful object.   If a little of it be placed in a watch-
                              6* 
66
THE  MICROSCOPIST.
glass, having another inverted over it, and then the lower one
heated over the  flame of a  spirit-lamp, the salt will be  sub-
limed.  Placed on the  stage of the microscope, with a power
of 30 diameters adjusted to  focus at the inner surface of the
upper glass, minute crystals will  be seen to form of a bright
yellow colour, which, as they cool, return to the original red.


                  VEGETABLE TISSUES.

   Vegetable 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.
   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
in various directions, giving its  surface a reticulated appear-
ance.  The form of these  reticulations varies  in  different
plants: in some they  are hexagonal, in others prismatic  or 
PROCURING  OBJECTS.
67
irregular.  Cuticles may be mounted  dry or in fluid.  The
geranium, oleander, &c, afford good specimens.
  The cuticle  of the  under side of the  leaf of many plants,
exhibits under  the microscope  dark spots  among  their 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
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 tis-
sue ;  their brilliant colours arise from the fluid contained with-
in 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.
   Vascidar  Tissue, prepared  by  maceration and  dissection,
presents many interesting subjects.  Spiral vessels  consist of
membranous tubes with conical  extremities,  internally  fur-
nished with one or more spiral  fibres.   As the vessels grow,
the spiral fibre breaks into short pieces,  forming rings.   The
vessels are then called annular.  If the pieces of fibre are  still 
68
THE  MICROSCOPIST.
shorter they are called dotted or reticulated vessels.   The root
of the garden rhubarb, the stem of the hyacinth, the leek, &c,
furnish examples.
   A peculiar form of vessel  is met with in the common car-
rot ; it is obtained from the 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
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. 
PROCURING  OBJECTS.
69
   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,  cf-c,  from equisetum,  straw, cane, &c,
are prepared  by heat  in a covered crucible, or by boiling  and
digestion  in  nitric acid.   The most  favourable example  for
showing the form in which silica  occurs in plants,  is the husk
of the oat or wheat.   If a husk of oat be  examined under the
microscope, having been mounted in water or Canada balsam,
a series of bright parallel  columns,  serrated  on each  side, may
be observed among the cellular tissue : if  another specimen be
burned carefully between the glasses, and  the ashes be mount-
ed in balsam, the siliceous columns will still be seen.  In the
ashes of the  husk of wheat,  rows  of concave discs may be
observed, which are composed  of some metallic oxide.  In the
ashes of the  calyx and pollen of the mallow, organized lime
may be detected.  In the ashes of coal, a  variety of  vegetable
structures, as cellular tissue,  spiral vessels, &c, may be  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
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.
   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 
70
THE  MICROSCOPIST.
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, enclos-
ing a fine mealy powder.  It  may  be compared in  some re-
spects to a common pea, in which the legumen is enclosed in
a testa or skin.  Starch granules  are not soluble in cold water,
nor is iodine  capable of acting on them while the membrane
enclosing its contents remains whole.  If the granules be tritu-
rated or immersed in hot water, the membrane will be ruptured,
and  iodine will then turn them blue.   Starch is readily sepa-
rated from wheat, potato, arrow-root, &c.,by repeated washings
in cold water.  To  obtain it from  rice,  the grains  should be
macerated for a few days, and to  prevent the decomposition  of
the gluten, a  little  soda should be added to the macerating
water.   Under the  microscope, the  surface of  starch-grains
often appears  corrugated, and each of them has one or two
bright  spots,  called the hilum, which  is supposed  to be the
part where the starch adheres to the cell.   Under polarized
light they present  the  beautiful  phenomenon  of  the  black
cross.   They should be mounted dry, and protected from the
pressure of the upper glass by a  rim  of thin paper. 
PROCURING  OBJECTS.
71
   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.   By scraping  hickory, or
other bark,  on to a slide, moistening it with the breath, and
blowing off  the woody particles; or by placing  a  part of the
ashes of a burnt maple leaf, coat of an onion, &c, on a slide,
such crystals may be seen.   They may be mounted dry or in
balsam.
   Mosses, are supposed to be destitute  of woody fibre and vas-
cular tissue.  When a leaf is carefully  examined, the septa
which  divide the cells are  sometimes found to take a spiral
course.  To observe this structure, soak the moss in water, to
expand the cells.
   It is essential, in collecting mosses, to preserve the 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.
   Algse.—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 colour, are the most  valuable.
   Ferns.—The  genera are  mainly distinguished by the posi-
tion and arrangement of  the organs of reproduction.   These 
72
THE  MICROSCOPIST.
are mostly on the under side, or along the margin of the leaf
or frond.   They are best examined as opaque objects.  They
should be  collected before  they are quite ripe.   The spores
(seeds)  are usually enclosed in brown capsules, each having
an elastic ring  about its equator, which when ripe bursts, and
the spores are dispersed to a distance.  Spores may be mounted
either as transparent or opaque objects.   The development of
ferns may be  observed by placing  the  spores in  moistened
flannel and keeping it at a warm temperature.  At first a single
cellule is produced, then a second, and so on.   After this the
first cellule divides into two, and then the others, by which a
lateral increase takes place.
  Lichens and Fungi  afford interesting objects.   The various
kinds of mildew  upon  vegetable  substances  are  familiar ex-
amples of minute fungi.
   Organic Fabrics possess  much  interest  in a  commercial
point of view, in  addition  to the  curiosity  arising from the
manner in which the threads or bundles of fibres are woven or
interlaced.   For  this  purpose they should   be  examined as
opaque  objects on a black  ground, with a magnifying power
of from 30 to 60 diameters.   The fibres of cotton are readily
distinguished  under the microscope  from  those of linen, wool,
&c.  Cotton fibres are tubular,  and are 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
wounds.
   Circulation in Vegetables.—The circulation  in plants, termed
cyclosis, is  a revolution of the fluid  contained in  each cellule,
and is distinct from those surrounding it.  It can be observed
in all plants in which the circulating fluid contains particles of 
PROCURING  OBJECTS.
73
a different refractive power or intensity, and the cellules are of
sufficient size and  transparency.  Hence all  lactescent plants,
or those having a  milky juice, with the other conditions, 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 frag ills. 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.

                ANIMAL TISSUES, ETC.

   Infusoria.—These  minute animals,  some of  which are
 only the 55Vfiotn Part of 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.
                              7 
74
THE  MICROSCOPIST.
   The  following table  exhibits the  families   or  groups  into
which  this interesting department of animal life has been divi-
ded 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.
CLASS  I.  POLYGASTRICA.
	'
Body destitute of appendages. (Nofoot-like <	Form of body * constant.
processes.) Gymnica.	
	Form of body variable. '
  Self-
 division
complete.
illoricated or shell-less,
loricated or shelled,
Monadina.
Cryptomonadina.
                      self-divi-  f self-dividing on all    "1
                       sion in-    sides (globular),     J

                      Tence"  un"ate»nf ^"°"-ted,
                      formedin I ^liS   \^^,
                      clusters.  (^

                      illoricated, .....
                      loricated,    .....

                (illoricated,     ......
Foot-like processes I          f compound foot-like  process \
     variable.   ■{ loricated J  from one aperture,        ]
                I         ' ] simple foot-like process from
one or from each aperture,
  Hairy
Epitricha.
illoricated,
loricated, •
Volvocina.
Vibriona.
Closterina.
Astasiaea.
Dinobryina.
Amoebaea.
Arcellina.

Bacillaria.

Cyclinida.
Peridinaea.
One receiving and f
discharging orifice J illoricated,
only for nutrition. | loricated,  -
   Anopisthia.    (.

Two ditto orifices, f
   one at each    J illoricated,
    extremity.    1 loricated,  -
  Enantritena.   L
Vorticellina.
Ophrydina.
Enchelia.
Colepina.
Orifice^ situated |illoricate(1 5 ^S^f "* *»} TracheJi

   Allotreta.    ] ,  .   . .  ' m°"th anterior, tail present, Ophryoc
Orifices abdomi
     nal.
   Catotreta.
[ loricated,
illoricated, ! ^motive organs cilii,
             do.     do.   various,
> illoricated, i
( loricated,
Ophryocercina.
Aspidiscina.
Kolpodea.
Oxytrichina.
Euplota. 
PROCURING  OBJECTS.
75
CLASS  II.  ROTATORIA.
Witt,, ,:m„i„ ...  [margin of  cilii-wreath entire.  ( illoricated, Icthydina.
UnuousSIwrPeath0of      .   . ^roeha         loricated, Oecistina.
      cilii.      \ marSm of "ln-wreath lobed or C illoricated; Megalotrochaea.
   (Monotrocha.)    {        fl-W^o.        ^loricated, Floscularia.

                 with the cilii-wreath divided into) illoricated, Hydatinea.
                        several series.        ) loricated, Euchlanidota.
With a compound
or divided wreath of
(So7-otrocha.)
Polytrocha.
cilii.       ' with the cilii-wreath divided into
^        Zygotrocha.
u-wreain aivmeu i™  nioricated, Philodinaea.
two series.        < ,  ■„ „,.„,,  ■a-nr.\,\n-r,aoa
loricated, Brachionaea.
  In reference to obtaining  infusoria,  some  persons imagine
that if they procure a portion of fetid ditch-water, or  take
a few flowers, &c, and macerate them  in water, they will  be
furnished in a few days with all the varieties they may desire;
but this is not the case.   Infusoria  will  of course be  found,
but they will be only of the  most ordinary kinds.   To  obtain
those  of  higher  interest,  some  degree of  skill  is  required.
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 Vorticellse, 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 
76
THE  MICROSCOPIST.
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
proper depth, or in the neighbourhood 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 
PROCURING  OBJECTS.
77
the animalculae will be on the surface of the mud, from which
they can be removed with the fishing-tubes (see page 47), and
placed under the microscope.
  If the  creatures are too  minute to be seen easily with  the
naked eye, pour a little water from the vessel containing them
into a  watch-glass,  and place it on a piece of 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.
  In  order to show the stomachs,  cilia, &c, of animalculae
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  colouring
matter may be put into the water on the slide containing  the
animalculae.  If they be vorticellae or rotiferae, the particles of
colouring matter will show the vibratile  actions of the cilia,
whilst other particles, swallowed  by the animals, will give a
rich tint to the compartments of their alimentary canal.
   Fossil Infusoria.—A great number of infusorial earths may
be  mounted in balsam  (test  objects dry, however,) without
washing, &c, but others must be repeatedly washed or digested
in acid.  For the skeletons or shields in carbonate of lime, Pro-
fessor 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 slight-
ly  fluid, without froth.
    Siliceous Shields of  Infusoria,  such  as those   in guano,
 Richmond  earth, &c, require to be well washed, and boiled or
                              •7* 
78
THE  MICROSCOPIST.
digested  in  nitric or hydrochloric acid.  After  this, a  small
quantity  of the sediment in which they are contained should
be placed on a number of slides, and those containing the best
specimens laid aside for mounting.
   Sponges.—These lowly-organized bodies are found both in
salt and fresh water in all parts of the globe.  Many of them
are very  minute,  and  may  be  examined without much 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  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
objects for examination, as  there is scarcely a part of the body
of an insect that  does not exhibit some remarkable structure.
   Antennse.—The horns of insects not only vary  in form in
different  genera,  but  in the  male and  female of  the  same
species.  They may be  mounted as  opaque, or  in Canada
balsam. 
PROCURING OBJECTS.
79
  Eggs.—The eggs of insects are generally of an oval form,
the outer covering being sufficiently rigid  to  resist  ordinary
external impressions; others are, however, soft and pliant. In
some  species they  are  globose, as in many Lepidoptera; or
conical, as in the large white cabbage-butterfly; cylindrical,
pear-shaped, barrel-shaped,  &c.   They are for  the most  part
smooth;  but many are very beautiful, ornamented with 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
cinereci) 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 colour
is very various,  although   white, yellow,  and green are the
most prevalent tints.
   In many species the eggs are deposited singly;  in  others,
they are  discharged  en 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 chrysorrhcea),  wrap them in  a coating of down, which
 they pull off their own bodies;  and the lackey moth (Lasio-
 campa Neustrid), 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 coloured, and form the most brilliant of all opaque 
80
THE  MICROSCOPIST.
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 splendour by
being  so  treated.   In order to ascertain whether an elytron
will be improved by  the balsam, one of the legs, or some part
supplied with a few of the iridescent scales, should be touched
with turpentine; if  the brilliancy  be increased, it  may be
mounted in balsam, if otherwise,. dry.   The elytra  of  some
beetles, after having been softened in  caustic potash, may be
mounted between flat glasses, as ordinary objects.
   Eyes of Insects, 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.
   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. 
                 PROCURING OBJECTS.               81

  If the  eye of a fly, or other insect, properly prepared by
mounting in balsam, be held near  the eye of an observer who
looks through it at a distant candle, &c, the  interference of
light in the minute lenses will cause a number  of images to be
perceived, tinged with beautiful colours.
  The eyes  of spiders are single.   They have from four to
twelve, variously  arranged.  Some  insects  have  also  single
eyes in addition to the compound  eyes before noticed.
   peet,—The structure of the feet of those insects which sup-
port themselves on polished surfaces, and  against the force 01
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.
   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 
82                THE  MICROSCOPIST.
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.
   Sdme 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 colours 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
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 neighbourhood of the  little  black spot 
PROCURING  OBJECTS.
83
or pustule, so as to force out the sebaceous  or oily matter.
This should be  laid on a slide, and  a small quantity of oil
added to separate the insects 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.
   Tracheee 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 is  alluded to on page 60.
   Stings, Ovipositors,  &c, frequently require considerable care
in dissection.  They may be mounted in fluid or balsam.
   Shells  of Mollusca.—The structure  of shell  has  only
lately attracted  the  attention of microscopists, but since the
year 1842  the  subject has been scientifically investigated by
Mr. Bowerbank  and  Dr. Carpenter.   According to the 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 crystalline 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-organized structure.
   All  thin sections of recent shell  are translucent, except
when the colouring matter is opaque,  or  when the  calcareous
matter is deposited in  a chalky state between the true laminas
of the shell, as  in the oyster.
   Dr.  Carpenter classifies  shells, into—1. Prismatic cellular
structure, as exemplified in the Pinnae.   2. Membranous shell
substance, as  the My a, Anatina, and Thracia.   3.  Nacreous 
84
THE  MICROSCOPIST.
or  pearl structure,  as  the inner surface of some  species of
Ostrea and 3Iytilus.  4. Tubular structure,  as the outer layer
of Anomia Ephippium, Lima scabra, &c.   In some cases the
tubes run at  a distance  from each other obliquely through the
shell, as in Area Nose.  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:

                     Enamelled Scales.
   1. Placoldians.  Cartilaginous fishes, having prickly  or flat-
tened spines, as the  skates, dog-fish, and sharks.
   2. Ganoidians. 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. Ctenoid ians.  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 
PROCURING objects.
85
 from the under surface of the  skin with  a knife or a pair of
 forceps.
   Some scales when viewed by polarized light have a brilliant
 effect. They may be mounted in balsam.  Fossil scales, as well
 as others, may be examined as opaque objects.
   Hair of Animals, &c.—Hairs are composed of an aggre-
 gation of epithelium  cells, and the colour depends upon the
 quantity of pigment  deposited  in  or about  each cell.  Care
 should be taken to select both the hair and the wool from each
 animal, as they differ materially in their structure; the  finer
 kind, or what is known as wool,  being  endued with  the pro-
 perty termed felting, which  property is of considerable impor-
 tance 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 struc-
 ture is not very apparent, but may  frequently be seen in fine
 specimens from very young  infants.  These,  however, should
 not be mounted in balsam.
  The smaller kind of hair may  be mounted  dry or in fluid;
or, if of a  dark colour, in balsam.   Horizontal and vertical
sections should  be made of  large  hairs and spines, which may
be done after gluing a number together, in the 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
                             8 
86
THE  MICROSCOPIST.
drying rapidly on the  slide and  covering with the thinnest
glass.
  The red corpuscles in man are of a circular flattened  form.
If water be  added to them, they become  spherical by 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
nucleus or spot in the  centre, and in the other a thickened
edge, like a  ring.  In all air-breathing, oviparous, vertebrated
animals, the blood corpuscles are  oval, and a nucleus may be
observed within each of  them.   This nucleus is rendered very
distinct by the addition  of a drop of diluted acetic acid.
  The observations  of Professor Owen  on the blood-discs of
the Siren lacertina,  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 4yotn of
an  inch,  while the  diameter of human blood-discs  average
.g-^^th of an inch.
   Circulation of Blood  may be seen in the web of a  frog's
foot (see page 46); in the fin or tail of a fish;  and in the legs,
&c, of many  spiders and insects,  especially  aquatic  larvae.
There is nothing so wonderful and pleasing as the sight of the
blood corpuscles coursing through  the vessels in the web of a
frog's foot, when  seen with a power of about  200 diameters.
The researches of  Kaltenbrunner; a distinguished German pa-
thologist; on the circulation of blood in a frog's foot, and the
influence of various  irritants upon it, as seen under the micro-
scope; have added much to our knowledge respecting conges-
tion and  inflammation, and are.  of  the highest interest  to the
practitioner  and student  of medicine.  They are referred to by
Dr.  Watson  in his preliminary lectures on  the  Practice of
Medicine, and their  importance clearly shown.
  Bone  should be  cut into thin  sections, about  ^th of an
inch in thickness.  They can be cut with a fine saw, such as 
PROCURING  OBJECTS.
87
are made of watchspring.  They should then be cemented on
a piece of glass;  filed to the proper thinness; ground upon  a
hone ; and polished by a leather strap or piece of cloth charged
with putty powder (oxide of tin and lead), or carbonate of iron
(rouge)r  They may be mounted dry or in  balsam.   Both
transverse and longitudinal sections should be made.
   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
does not occur  in all the cells, as the bone requires to grow
and be nourished;  hence  arises its  peculiarity of structure.
Independently  of the  hollows,  or cancelli,  the hard part of
the bone is  traversed by canals, called Haversian, which run
in the direction of the 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.   Among these layers  dark
specks are dispersed.  These  dark specks (called lacunae;  or
corpuscles of Purl;inje), 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- 
88
THE  MICROSCOPIST.
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
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 -joVo^h 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 colouring matter by Dr. White, of Philadelphia.
On  the  ends of the dentine  tubuli are placed the ends  of  the
enamel  prisms, in the human tooth.  Dentine is now established
by Professor  Owen as an ossification of  the pulp of the tooth. 
PROCURING OBJECTS.
89
3. The Bone or 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.—In some animals, as fish, the skin is not very vascu-
lar, while in the mammalia, and, perhaps, in the human subject,
it attains the highest state of organization.  The skin performs
a function in the animal  economy second  only in importance
to that of the lungs, and for  the purpose  is supplied with a
very rich capillary  network;  and also provided with two or
more sets of glands, one for secreting the  perspiratory fluid,
the other an unctuous or sebaceous matter for lubricating  the
skin itself.  Taking the human skin as an example, we should
commence the study with vertical sections, made through parts
supplied both with hair and 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 rendered firm enough for vertical section by
hardening in a saturated solution of carbonate of potash  or in
strong nitric acid.  The capillary network of the cutis vera
may be seen in injected specimens when the  cuticle has been
removed, which will often  require the  aid of maceration  for
the purpose.   If the skin be that of  a black man, care should
be taken in  the  removal of the cuticle, as in it may be  ex-
amined the rete mucosum, or coloured layer, which consists of
a series of minute hexagonal cells, containing pigment.   The
same structure may be seen   in the  skins of animals whose
                            8* 
90
THE  MICROSCOPIST.
hairs are black; for this  purpose the lips of a black kitten,
when injected, should be  selected,  as in them the  mode  of
growth of the young whiskers, their copious supply of blood-
vessels and nerves, and various  other points of interest, may
be observed.  The papillae are best shown in the extremities of
the fingers and toes, when  injected; the cuticle which invests
them should also be mounted as an  object, with its attached or
papillary surface uppermost, as in  this  the  grooves for their
lodgment, together  with  the openings of  the sudoriferous
glands, can be well seen.
  Eyes.—Many objects of interest may be obtained  from the
eyes of various animals; as the crystalline lens, the  pigment,
the ciliary processes, the  retina, and the membrane of Jacob.
The structure of the  crystalline lens in  fish is best seen  after
the lens itself has been hardened by drying, boiling, or long
maceration in spirit.   After having peeled off the outside, the
more dense interior will be found  to split up into concentric
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 humour 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. 
PROCURING OBJECTS.
91
   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,
&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.  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, espe-
cially with polarized light, show a longitudinal arrangement of
cells.   Perhaps the true structure is a compound of both these
modes; the sheath being spiral, and the  ultimate fibre longi-
tudinal.
   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, in the  thin recti muscles of
the eyes of small birds.   By the use of the compressor,  these
latter,  if  seen soon after  death, will, without injection,  show
both nerves and capillaries.
   Nerve.—The dissection of nerves, to  show  their ultimate
structure, is  similar to that of muscle, above  described.   It
should be performed, however, in a little serum  or white of an
egg;  as water, &c, changes its  appearance.   As soon as the
true structure has been well seen; water, ether, &c.; may be 
92
THE  MICROSCOPIST.
 added, to show how much they change its original appearance.
 In all examinations of nerve or muscle; the more delicate the
 structure, the sooner after death should it be dissected.
   Fibrous and Areolar Tissue.—Nearly allied to 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 colour, the white fibrous
 tissue; a mixture  of the two is  known to  anatomists as the
 areolar tissue,  and  is largely used in the  animal  economy,
 as it forms a support  for all the vessels,  nerves,  and  mus-
 cles,  from  either  of which  it may be  easily procured.   The
 yellow tissue is  found in nearly an isolated condition in the
 ligamentum nuchas of the  necks of some  animals,  especially
 of the ruminating tribe; it also enters largely into the forma-
 tion of the  intervertebral discs.   A portion of the ligament
 from  the neck of  a sheep or  calf, even  after boiling, will ex-
 hibit  the elastic fibres  exceedingly well; they  are  of nearly
 uniform size, generally curled at their extremities, and  of a
 yellowish colour.   They may be prepared as muscle or nerve,
 with the needle points.
   If  any of the above tissues are  to be kept they should be
 mounted  in fluid, as spirit and water, or the creasote liquid.
   Mucous  Membrane.—This is  the  investment of all  the
internal parts of the body, continuous with the skin.  Every
cavity, organ, or gland, which opens on the surface, is lined by
it.  Shut sacs are  lined by serous membrane.
   The mucous membrane may be divided into two parts:  the
epithelium, and the basement membrane.  The external  skin
is  evidently a similar  structure,  somewhat  modified, and is
capable, under certain circumstances, of taking on  a similar
function.   The epithelium of skin is the cuticle or epidermis,
but the basement membrane, though  present, is not easily
 shown, except where the surface is raised into papillae. 
PROCURING OBJECTS.
93
  The epithelium  exists in three  varieties:  the  scaly, pris-
matic, and spheroidal.   The first kind is most largely deve-
loped in the skin; the cuticle, with its horns, hairs, hoofs, and
feathers,  &c, is  made up of it.  Detached scales may  be  ob-
tained from the inner side of  the mouth,  &c.   The prismatic;
or, according to Dr. Todd, the columnar; is abundant throughout
the stomach and intestines, and even the  lungs.  Each prism
is attached by its sides to its fellows, and  endwise to the base-
ment 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
intestines.  It is supported upon a submucous areolar  tissue,
in which both the blood vessels and nerves ramify, but do  not
in any case enter the  mucous membrane.
   In order to  examine the surface of  mucous  membranes,  the
mucus should  be washed off as gently as possible, by a small
stream of water or a  small syringe.  If the epithelium be 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 
94
THE  MICROSCOPIST.
form a layer of cuticle, it must be removed by maceration, in
order to see the mucous surface.
  The arrangement of the capillaries, as seen in the injected
mucous membranes, is exceedingly interesting, and forms a 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  will speedily  stop.   The  motion  and
structure of the  cilia is sometimes better  observed after the
lapse  of some hours, as the movement will then have become
sluggish.
  Injected Preparations.—We have  already  referred to
the arrangement of the capillaries in mucous membranes, mus-
cular tissue, the  eye, &c.   A collection of such preparations is
of considerable importance.
  There can be no doubt, but that the blood is, par excellence,
the vital fluid.  From it  is  derived the material for the deve-
lopment of each part of the organization ; nerve, as well as mus-
cle, bone, tendon, &c.   Even unnatural  and morbid growths
must have their origin in some alteration in this  all-pervading,
all-sustaining fluid.   " The life thereof is  the blood thereof."
  The capillary vessels of the  body form the vehicle of vital 
PROCURING  OBJECTS.
95
distribution and stimulus.  By them is conveyed the nutrition
of all the tissues;  and through them all foreign substances are
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
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
otherwise can we account for the different sensations  produced
by inflammation in different tissues; as for instance, the burn-
ing, 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, 
96
THE  MICROSCOPIST.
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
produce delirium, and illusions of  special  sense:—impressions
being made on  the sensorium independent of the action of
usual external stimuli.
  The theory above referred to,  in order to explain or account
for  these phenomena, may be expressed as follows:—The
principle of life, or the capacity for vital  action, is a property
impressed by the Great Creator upon the material organization
of both animals and vegetables.   In addition to  this,  the 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-
tions of volition  and sensation,  that  the nerves  should  be
supplied 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
remark.   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 electri-
city fail to discover it, when applied to nerve in action—that a
ligature to a nerve stops the propagation of nervous power, but 
PROCURING  OBJECTS.
97
not of electricity—that if a piece of nerve  be cut out  and be
replaced by an electric  conductor, electricity will be 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.
   It may be mentioned,  however, that this view will throw
great light upon the cause and cure of insanity, as well as other
diseases; and  upon the modus  operandi of many articles  of
the materia medica.  It is, indeed, a  question worthy to be
entertained,  whether diseases, which  are so  clearly divisible
into  sthenic and  asthenic, may not,  after all, chiefly result
from  an alteration of tone or capacity in the  capillaries of an
organ,  tissue,  or  of the whole  system.  Cullen's idea,  that
fever is caused by a spasm in the capillaries, may not be far
from  the truth, though it be but a theory.
   To sum up all which our  present  limits  will allow;  the
capillaries are the most interesting and important vessels of the
body, and  yet, perhaps, the  least studied.   A work specially
devoted  to them—their description and properties—would be
a valuable accession to physiological science.
9 
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 
TEST  OBJECTS.
99
small holes.  The various colours are seen according to the
order of their refrangibility,  by putting the object both within
and without the focus, as well as by viewing it at the focal point.
   Spherical aberration is most sensibly felt in viewing opaque
objects, especially if  of the brilliant class.   It shows itself in
a variety of ways: first, as a  diffused nebulosity over the whole
field of view; secondly, as  a  confined nebulosity, extending
only to a certain distance  from the object;  and thirdly, in a
want of sharpness and  decision  in the  outline  caused by a
penumbra or double  image, which can never be made to lap
perfectly over the stronger or true one.  Destitution of 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 colours.
   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 colour,  except  a
general blueness, which results from the irrationality of the
spectra  of  the different glasses of which the object-glass is
composed. 
100
THE  MICROSCOPIST.
  Power of definition  depends, in a great  measure, upon  the
angle of aperture of the object-glass.   A deficiency of angular
aperture is shown by a want of light, producing 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. 23 and 24, represent two objects,
in all respects  alike;  and suppose B, B, and b, b, to be  two
object-glasses of equal focal length;  the former a single lens,
of the best construction, such as was used in the old compound
microscope, and the latter a lens of  the newest form,  termed
an achromatic.   Now  these object-glasses will  form their 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.
101
  The angles B, A, B, and b, a, b, are the  angles of aperture
of the respective  object-glasses,  and  the  quantity of light
transmitted will be as  the squares of B, B, and b, b, their focal
length being equal.
  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.
                             9* 
102
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 instrument.
  Bat's Hair.—This is a most beautiful structure, presenting
a series  of scale-like projections arranged in  the form of a
whorl around the central part  or shaft.   They are least 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 colour 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
coloured should be  preferred.   Like the scales on insects, the
hair from different parts of the  same individual varies con-
siderably  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,
consisting of several  large filaments or spines,  which are 
TEST  OBJECTS.
103
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 com-
mon, the striae should be seen over the whole surface.  Some-
times the  scales  are damaged, the pigment having been re-
moved; in such cases the cross striae cannot be seen.   The pig-
ment,  under  very high powers,  exhibits a dotted  appearance
between the striae.
   Tinea Vestianella, or  Clothes Moth.—The scales of  these
insects 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 easy. 
104
THE  MICROSCOPIST.
  Poutia 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 ap-
pear to be composed  of rows of little squares or beads.
  Podura plumbea,  or Lead- Coloured Springtail.—The body
and legs of these tiny  creatures  are covered with scales of
great delicacy.   The surface of each,  under a power of 500
diameters,  appears  covered with numbers of delicate wedge-
shaped dots or scales, arranged so as to  form both longitudinal
and transverse wavy markings.  A very small scale is a good
test of the defining  power  of a one-twelfth or one-sixteenth-
inch object-glass.  The small scales may easily be rubbed  off
the scale to be examined, unless great care be taken in mount-
ing, &c, and, of course, it will be useless as a test objeet.
  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
projections from the surface.   The Navicula 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.
   As  it is always  a tedious matter with  the use of a high
power to find a  minute  object on the slide  under the stage, it
will be most convenient to bring it first into the centre of  the
field by the use  of a lower power, and afterwards substitute the
 high power object-glass. 
CHAPTER  VIII.
 ON  DISSECTING  OBJECTS  FOR THE MICROSCOPE.

   Reference has already been  made  in Chapter V. to the
manner of dissecting and preparing certain animal and vege-
table 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. 25.
blades are  kept open by a spring, a, Fig. 25, was much  used
by Swammerdam in his dissections.   One of the handles is 
106
THE  MICROSCOPIST.
attached to a piece of wood, b; the other is curved  as at c, in
order to be pressed upon by the thumb or forefinger in the act
of cutting.
  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. 26.
ney, a knife with two parallel blades, called Valentin's Knife,
Fig. 26, may  be used  with advantage.   Dissecting needles
may be straight or curved.   One of the latter, fixed in  a pro-
per handle, is represented in Fig. 27.  These are very service-
able instruments for separating or tearing asunder delicate
tissues.
                            Fig. 27.
  As most dissections are made under water, convenient troughs
are necessary.  They may be from  two inches to a foot long
and of a proportionate breadth  and depth.   Earthenware,  or
glass, is  the best material.
   Loaded corks are flat pieces of cork covered on their under
surface with sheet  lead, so that they may readily sink in the
water.   To these corks the subject to be dissected  is fastened
with pins. 
DISSECTING  OBJECTS.
107
  Bests 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.
  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- 
108
THE  MICROSCOPIST.
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
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  trachea, 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 pre-
serve 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 
DISSECTING OBJECTS.
109
them, with very little trouble, from the exuviae, or skins, with-
out any danger to the parts; so that  by this  contrivance the
pupa could be shown to be wrapped up in the  caterpillar, and
the butterfly in the pupa.
  Those who look into the works of Swammerdam, will be
abundantly gratified, whether  they consider his immense la-
bour and unremitting ardour 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.
  To render this section more perfect, a few further remarks
on the internal  anatomy of insects will not be out of place.
For the anatomy of other parts of the animal organization, the
reader is referred to Chapter V., and the usual text  books.
  1. Tracheae,  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. 28 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
                            10 
HO               THE  MICROSCOPIST.
small trough with water, and be securely fixed to a loaded cork.
The body being laid  open, next to the large viscera, the tra-
cheae  will become visible.  The stomach and intestinal canal,
if  large and transparent, will exhibit the minute ramifications

                          Fig. 28.
of 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 mount-
ing, 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 
DISSECTING OBJECTS.
Ill
dissection.   They may be cut from the body with a scalpel or
pair of scissors, and be mounted in fluid or in balsam.
  2.  The Digestive System consists of the pharynx;  the eso-
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  very great  variety in the  digestive apparatus of
insects.  In those which feed on flesh, the alimentary canal is
short, as in the higher animals, and in the vegetable  eaters it
                           Fig. 29.
is long.  There are also differences of  structure, which clearly
show the adaptation of means  to ends.  A, Fig. 29, is the
digestive system of Melolontha.   B, is that of  Blatta Ameri- 
112
THE  MICROSCOPIST.
 cana (American Cockroach), a is the esophagus, b the crop, at
 the  bottom of which is  the  gizzard, c,  consisting of several
 teeth arranged like a funnel, with  the  apices of the teeth in
 the centre.   Another view of the gizzard is seen at C.   The
 bile-tubes or liver are shown at d, and the salivary glands at e.
 Attached to  the  stomach, just below  the gizzard, are  eight
 blind sacs,/,  the  use  of which is  unknown, but  is  supposed
 to be analogous to the pancreas.
   The  salivary  glands, stomach,  &c,  should be generally
 mounted in  fluid.  Gizzards may be put up in balsam.   The
 gizzard of a cricket is an interesting object; it has  over  two
 hundred teeth.
   3. The Nervous System  consists  of two  medullary cords or
 threads, which run along the middle of the abdomen inside,
 exhibiting  a series of knots or ganglia.
   Fig.  30 exhibits the nervous system of a caterpillar, from a
 preparation of Dr. Goadby's.   The double ganglion, A, seems
 to occupy the place of the cerebellum, and B, also double, and
 transverse  to  the others, answers to the cerebrum.   C, C,  the
 two  cords  uniting them.   E, the  space through  which  the
 esophagus  passes.  F, F, F, the ganglia which  unite the  two
 cords.   The distribution of the  nerves  through the body is
 from the ganglia.  The  apparent exceptions to  this, as  at D,
 are proven,  by Dr. Goadby's investigations on the Limulus, to
 be, in fact,  arteries, as they have been  injected.  Coagulated
 insect blood is white, hence they appear like nerves.
  4. The Circulatory System is  placed  along  the back, and
 consists of  a heart or  dorsal vessel;  which is a tube divided
 into chambers, separated from each  other by valves.  There are
 also valves  at the sides  to receive the blood from the venous
sinuses  of the body.  But a single artery has been  seen, which
goes  to  the head, dividing into three branches.  It was thought
that the blood exuded through the  vessel and found its  way
through the body as it best could,  back to the  heart; but in 
DISSECTING OBJECTS.
113
dissecting a Limulus (king-crab), Dr. Goadby traced the artery
into certain large sacs or vessels, evidently answering the pur-
pose of veins (venous sinuses).   It is probable the same holds
Fig. 31.
\)A
good of insects.   Fig. 31 represents the dorsal vessel in the
larva of Ephemera.  The  arrows indicate  the current of the
fluid.
  The muscular system of insects  is very extensive.   Lyonet
dissected and described 4061 in the caterpillar of the goat moth
(Cossus ligniperda).
                            10* 
CHAPTER  IX.
        THE  CELL-DOCTRINE OF PHYSIOLOGY.

   Reference has already been made at  page 96 to the cause
of vitality; alluding to it as a peculiar  property impressed by
the Creator on all organized structure,—a property altogether
distinct from  Volition and Sensation, which exclusively belong
to animals, and which point out the existence of a special entity,
or being, resident in the organism, but whose  properties can-
not 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 reasonable to define it as a peculiar  property of organi-
zation ; as gravitation, electricity, &c, are  special properties of
matter under other circumstances, the essential nature of which
are just as mysterious as that of Life.
   Mysterious as this subject is, it is nevertheless interesting to
trace the origin and development of organized structures; and
the progress of modern science has  supplied us with the means 
       THE  CELL-DOCTRINE OF PHYSIOLOGY.   115

of instruction.   Chemistry teaches us that the ultimate ele-
ments 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 ob-
tained 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 Wbhler.
   " The simplest and most elementary organic form with which
we are acquainted, is that of a cell,  containing another within
it (nucleus), which again contains a granular body (nucleolus)."
See Fig. 32.
   " This  appears, from the interesting researches of Schleiden
and Schwarm, to be the  primary form which organic mat-
ter  takes when it passes from the  condition of a proximate 
116               THE  MICROSCOPIST.

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. 32.
produced by the simple solidification of the plastic  or organi-
zable fluid :  this fluid is, however, prepared by cells, and is set
free  by their rupture.  This  seems  to be  the case with the
delicate membrane known as the Basement or Primary Mem-
brane, beneath the  epidermis or epithelium.  According to
Dr. Carpenter, in many specimens  of this membrane, no ves-
tige  of cell-structure can be  seen,  and it  resembles that of
which the walls of the  cells are themselves constituted.  In
other cases it presents a granular appearance under the  micro-
scope, 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  exist-
ing,  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 xu<ro£, a vesicle, and /3Aaso?,
a germ), or cell-germ.   From  the side of this  nucleus a  thin
transparent membrane  projects  like a watch-crystal from the 
       THE  CELL-DOCTRINE OF PHYSIOLOGY.    117

dial, and gradually enlarges till at last the nucleus is seen only
as a spot on its wall.  The whole  is then  called a nucleated
cell, or germinal cell. The fluid in which the granules are first
deposited is called 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 haematodes, which infest the body,
are owing to the same agencies. In short, the nucleated cell is
the agent of most of the organic processes, both  in the plant
and animal, from the  dawn  of their existence to their full
maturation and decline.
   The forms of cells are various;  some being spheroidal, others
cubical, prismatic, polygonal, or cylindrical.  They are subject
also to  various  transformations.   Sometimes  a  number  of
cylindrical cells are  laid end to end,  and  by the absorption of
the transverse  partitions  form a continuous tube; as  in the
sap vessels of  plants, muscular and nervous fibre,  &c.
   At other  times  the cells are elongated and  fusiform, as  in 
118
THE  MICROSCOPIST.
woody fibre; or they may  send forth prolongations, assuming
a stellate or irregular appearance, as  in the  pigment  cells of
the Batrachia and Fishes, or some of the vesicles in the  gray
matter of the nervous  system.   Further, the original  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. 33.
nium-petal, Fig. 33;  this seems  also to be the case with the
nuclei of the bone cells.  In other  cases it seems  to resolve
itself into a fasciculus of fibres; and  this Henle conceives to be
the origin of  the yellow fibrous tissue.   Further, it may sepa-
rate into a number of distinct fibres, each composed of a linear
aggregation  of granules; in  this manner, the dental tubuli
appear  to be  formed.  Lastly, Dr.  Carpenter thinks it  may
disperse itself still more completely into its  component gra-
nules ; by the reunion of which certain peculiar vibrating fila-
ments (the so-called spermatozoa) may be formed. 
      THE CELL-DOCTRINE  OF  PHYSIOLOGY.    119

  " In the lowest and  simplest forms of living beings," says
Dr. Carpenter, " such as we meet with among the humblest
cellular  plants, we find  a single  cell making up the  whole
fabric.  This cell grows from its germ, absorbs and assimilates
nutriment, converts a  part  of this into  the substance  of  its
own  cell-wall, secretes another portion  into  its cavity, and
produces  from  a  third  the  reproductive germs that are  to
continue the race; and having  reached its  own term of life,
and completed the preparation  of these germs, it  bursts and
sets them  free—every one of these being capable, in its turn,
of going through the  same  set of operations.   In  the highest
forms of vegetable life, we find but a multiplication of similar
cells; amongst which  these operations are  distributed, as it
were, by  a division of  labour;  so that, by  the  concurrent
labours  of all, a more  complete and permanent effect may be
produced."
  Of the  development of animal tissues, Todd and  Bowman
present  the following interesting account, in their  "Physiolo-
gical Anatomy 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. 32, page
116), has  been described and delineated as the simplest  which
organization produces.   It  consists of a vesicular body filled
by a fluid, and enclosing another, within which is a third, 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,
or the germinal vesicle of the egg, is the nucleus of the first:
and the third, which is called by  embryologists the germinal 
120
THE  MICROSCOPIST.
spot, is  a nucleolus to the second.   It appears, from  the  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  takes
place.  The granules  cohere to each other in separate groups
here  and there, to form nuclei,  and around each  of  these a
delicate membrane is formed, which is the  cell-membrane.
   " In  every part of  the embryo the formation of  nuclei  and
of cells goes on in one  or  both of the ways above mentioned;
and, by and by, ulterior changes take  place, for the production
of the  elementary parts of the tissues."
   The  mode of development just referred to may be illustrated
by the  following cuts.   Fig. 34  exhibits a section of one of
the branchial  cartilages of  the  young  tadpole.   Within the
large parent-cells, that  are held together by intercellular sub-
stance, a,  b, c, we observe secondary cells in various  stages of
development: at d, the nucleus is single; at e,  it is  dividing
into two;  in  the adjoining cell, the  division into  two nuclei,
d' and  e', is complete;  at h, two such nuclei are enclosed within
a common cell-membrane; at i, we see three new cells (one of 
THE  CELL-DOCTRINE  OF  PHYSIOLOGY.
121
them elongated, and probably about to subdivide) within the
parent; and in each of the  two groups at the top and bottom

                           Fig. 34.
of the figure, we have four cells, separated by partitions of in-
tercellular substance, but  having manifestly originated from
one parent cell.
   Fig. 35 represents endogenous cell-growth in cells  of a me-
liceritous tumour; a, cells presenting nuclei in various stages
of development  into  a new generation;  b, parent-cell filled
with a new  generation of young cells, which have originated
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
principal character is extension, but  its ultimate  structure de-
fies the highest powers of the microscope.—Examples are seen
in the  posterior layer of the cornea, capsule of the lens, sar-
colemma of muscle, &c.
                            11 
122
THE  MICROSCOPIST.
  2. Simple  fibrous tissues, including the white  and yellow
fibrous tissue, and  the  areolar tissue, which is formed from

                          Fig. 35.
them.  Ilenle 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 epi-
dermis) ; or of areolar tissue and epithelium; as mucous mem-
brane, skin, secreting glands, serous and synovial membranes.
   6.  Simple  isolated cells,  forming  solid  tissues  by their
aggregation;  as fat cells, the vesicles of gray nervous  matter, 
       THE CELL-DOCTRINE  OF PHYSIOLOGY.   123

absorbent cells of the villi, and the cellular parenchyma of the
spleen.   In these cases the cells are held together by the blood-
vessels  and areolar tissue, which  pass  in between  them; in
cartilage, and other tissues allied to it in structure, the cells are
united by intercellular substance, either homogeneous, or of a
fibrous character.
   7.  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
characteristically 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 ab-
normal  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, dissect-
ing needles, and Valentin's knife, will be useful.
  If  the subject  for  examination  be fluid, as blood, pus, mu-
cus, &c, a very small quantity should be put on a clean slide,
and covered with a piece of thin glass.  A fishing-tube (page
47) will be of service for this purpose.
  If there be sediment in the  fluid, it should be allowed to 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 
              MORBID  STRUCTURES,  ETC.          125

each other so nearly in many of their characters, it becomes
of importance  to  have some test whereby they may be dis-
tinguished from  each other.  The  fluid employed  for this
purpose is acetic  acid.  When this  is  added to a fluid where
pus is present, the globules swell  up, and several large, trans-
parent nuclei make their appearance;  but when it is added to
a fluid where  mucus is present, the  globules  also enlarge and
show their nuclei, but not so plainly as the pus, and the liquid,
termed liquor muci, in which  the globules float, is instantly
coagulated into a semi-opaque corrugated membrane.
   The  presence  of  fatty matter  is ascertained  by  sulphuric
ether, which  readily dissolves the  oily part, and  leaves the
membranous cell-wall untouched.
   Earthy matters require the aid of the acids  for  their solu-
tion ; these should  be added in a dilute form, so that  their
solvent action may be more easily witnessed.
   Solid  parts, as tumours, &c,  that are to be examined as
transparent objects, with  high powers, require to be cut into
very  thin slices,  and separated,  if necessary, by the  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 inad/nissible.
   It is necessary to state, that the examination of all  morbid
structures should be made as  soon as convenient  after  their
removal from the body,  as changes of form in the  softer sub-
stances  speedily  take place;  but if some  time  has elapsed,
the part from which the sections  are  taken should  be at some
distance from  the surface, in order that they may be as  little
altered as possible by  the action of the air.
   The foregoing directions have been condensed from those of
                             11* 
126
THE  MICROSCOPIST.
Mr. Quekett, to whose book we have already been much in-
debted during the progress of  this work.
  It was at one time  " fondly hoped"  (says Dr. McClellan),
" that by the aid of powerful microscopes we could be able to
detect  the  pre-existing germs of all organic diseases in the
general circulation, and decide not  only as to the species  of
affection, but also concerning the  degree of constitutional 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 practi-
cal  knowledge from the use of the  microscope than what is
connected with the minute anatomy of  the morbid structures
after they have been elaborated."   With  all  deference  to the
opinion of so truly a great mind  as the lamented McClellan,
we may be permitted to remark, that notwithstanding much
has been done by the labours of European and other observers,
minute pathological observation is still  in its infancy; yet it
has made a deep impression upon  the study of medical science.
When  "the minute anatomy of the  morbid structures" shall
be fully known, our  knowledge of organic diseases will have
advanced  to  a great  degree of perfection.   Dr. McClellan is
not himself  insensible  of the  advantages to be derived from
microscopic  investigations, although we  think  he places too
little value  upon them.   He  says,  " Chemical analyses and
microscopic researches  have lately proved that a great  number
of cases (of tumours) which were  once thought to be scirrhous,
or cartilaginous, or osteo-sarcomatous, are really composed of
condensed fibrine of the blood, sometimes partially altered into
albumen or gelatin." 
MORBID STRUCTURES,  ETC.          127
  The microscopic appearance of a fibrous tumour is exhibited
in Fig. 36 (after Vogel).  It shows interlacing fibres, C. Pri-

                           Fig. 36.
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.
   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 some-
times in  the substance of the lungs and spleen.  Fig. 37 shows
the microscopic appearance of typhous matter from the mesen-
teric glands.   A, an amorphous, slightly granular  mass, of a 
128
THE  MICROSCOPIST.
brownish-white colour, with an immense number of cells depo-
sited;  B, the amorphous mass  treated with  acetic acid, by
which  it was rendered transparent, and gradually dissolved,
Fig. 37.
upon which  many minute cells with a sharp outline came into
view, being unaffected by the acid (Vogel).
  There seems no distinction between tuberculous matter and
that of scrofula  or  typhus.   Fig.  38  exhibits  tubercles  in
various stages of development.  A, B, C,  tubercles from the
lungs of a young man who  died of tuberculosis pulmonum.
  A, B, nuclei in an  amorphous cytoblastema;  most of the
nuclei  contain nucleoli.  At C  the cytoblastema has 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. 
MORBID STRUCTURES,  ETC.           129
  2. Carcinoma.   In  cases  of  true scirrhus, the  matrix or
stroma is constituted either by a new development of cellular
texture, or by an induration and enlargement of the original
areolar tissue of  the part.   The larger and coarser fibres  and
Fig. 38.
lamellae of this tissue become converted into  dense and firm
ligamentous  bands,  which  intersect  each  other  in various
directions.
  Vogel,  and some other writers, describe  a  second kind of
fibres, which occur in a reticulated form, cross-barred, or in
irregular meshes.   They are distinguished from the first-men-
tioned whitish  or  ligamentous bands, by being insoluble in
acetic acid.   Fig. 39  (from Vogel, after Miiller),  shows the
Fig. 39.
fibrous  stroma of scirrhus, as  seen  in the microscope.  The 
130
THE  MICROSCOPIST.
meshes  are formed by bundles of carcinoma reticulare of the
breast, as they appear after the globules have been removed.
   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. 40.   Small masses that had been pared from
a recent section of the  tumour, 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. 
MORBID STRUCTURES,  ETC.           131
The greater number exhibited nuclei, a, b, and in some a nu-
cleolus was visible in the nucleus, c, h;  few were devoid  of

                           Fig. 40.
nuclei; on  some  fat  globules were  observed,  g.   Between
these cells were perceived  nuclei with or without nucleoli, d.
(Vogel.)
   3.  Encephaloid  disease or  fungoid  tumour,  differs from
scirrhous  cancer chiefly in the great predominance of its transi-
tory or morbidly developed  cells over the fibrous and other
elementary  textures which constitute the  stroma (matrix) of
the tumour.  In carcinomas, the  fibrous tissue  predominates
and gives  solidity and firmness to the whole mass.  The morbid
or cancer  cells never tend to  develope organized fabrics,  but
always  to disintegration  and softening  down of the tumour.
Their great predominance in encephaloid, therefore, gives  the
character  of brain-like softness and yielding, which is the  dis-
tinguishing characteristic of  this form of malignant growth.
   Fig. 41 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. 
132
THE  MICROSCOPIST.
Here and there some  nuclei were  seen in an amorphous cyto-
blastema.
Fig. 41.
  Although the  cells of encephaloid belong to  the  class of
effete or transitory cells which  also occur in cancer, yet there
is a difference in the proportions of various kinds of these cells
in the two classes of tumours.   The predominating cells of this
kind in fungoid tumour are the very large parent cells, with
numerous young cells or cytoblasts in their interior.  They are
often as large  as -j^th of a line in diameter;  and the caudate
cells are always irregularly caudate or ramifying.
  There are seldom  any of the regular caudate or elongated
cells of small size, such as  go  to the formation  of the cellular
and  fibrous tissue, and of true cancers.   The fat cells and
granules are perhaps more  abundant than in scirrhus.  Fig.
42 is the microscopic appearance of encephaloid,  consisting of
cells of different size and form;  round, oval, and caudate, but
no one form predominating over the rest.  Some are very large,
a, enclosing several minute cells with  nuclei.  Isolated cells,
although in a proportionately small  number, contained dark
granules, b.   For further observations on  microscopic  patho- 
              MORBID  STRUCTURES, ETC.          133

logy, the reader is referred  to Vogel's Pathological Anatomy,
and other similar works.
   The Monthly  Journal of Medical Science for May, 1847,
contained an account of a new instrument for the diagnosis of
tumours.   It was presented to  the  Medical Society of 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 tumour to any depth, we can extract a minute
portion of the tissue of which its various layers are  composed.
In this manner a microscopic examination  of the tumour  can
be practised on the living subject, and its nature ascertained
before having recourse to an operation."
   With  respect  to  the  Morphology of various  pathological
fluids, a great deal has been effected by microscopic 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,  31.D., which are worthy of careful
perusal and experimental  verification.  The  results  of  Dr.
Gruby's researches may be found in a tabular form  at  the  end
of this volume.
                            12 
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 colouring  matter as
may be desirable,  as 3  ounces vermilion,  2 ounces King's
yellow, 10 ounces blue verditer, or 5 J ounces flake-white.
   This, injected into the blood-vessels by a proper  syringe,
having its pipe fastened in one of the largest of those vessels,
is  abundantly sufficient to show the course of the  principal
 arteries and  veins.   The  parts so injected may then be dis- 
ON MINUTE  INJECTIONS.
135
sected for this purpose, dried, and varnished, and form excellent
illustrations of anatomical lectures.
  When, however, it is desired to demonstrate the capillaries,
a finer injection  and more delicate manipulation is  required.
Indeed, it is so difficult an art, and success is so dependent on
the combination  of various  circumstances, that the  most 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. 43 represents a syringe, with which I have succeeded
in making some excellent  preparations.  A is the cylindrical
brass  body, on the  top of which  screws the  cap, B, a leather
washer being  interposed to render it more air-tight.   C is the
piston,  which  is  of brass, covered with wash-leather.   The
bottom  of the syringe, 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
forwards.  A half-dozen  pipes, at least, are necessary to ac-
company 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.
  To prepare  the  material for injecting:—Take of the finest 
136
THE  MICROSCOPIST.
and  most  transparent  glue, one pound; break it into small
pieces, put it into an earthen pot,  and pour on it three pints
of cold water;  let it stand twenty-four  hours, stirring it  now
Fig. 43/
and then with a stick ;  then set it over a slow fire for half an
hour, or until all the pieces are perfectly dissolved; skim off 
ON MINUTE  INJECTIONS.
137
the froth from  the surface, and strain through  a flannel for
use.  Isinglass, and cuttings of parchment make an excellent
size, and are preferable for very particular injections.
   The size thus prepared  may be coloured with any of the
following:
   Red.—To 1  pint of size, 2 ounces of Chinese vermilion.
   Yellow.—Size, 1 pint,—chrome yellow, 2 J 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 colouring matter
is employed, must be very finely levigated before it is mixed
with the injection.   This is a matter of great  importance, for
a small lump or mass of colour, dirt, &c, will  clog the minute
vessels, so that the injection will not pass into them, and the
object will be defeated.
   The mixture of size and colour should be frequently stirred,
or the colouring matter will sink to the bottom.
   Respecting the choice of a proper  subject  for injecting, it
may be remarked, that the injection will usually go farthest
in young subjects; and the more  the creature's fluids  have
been exhausted in life,  the greater will be the success of the
injection.
   To prepare the subject, the principal points to be aimed at
are, to dissolve the fluids, empty the vessels of them, relax the
solids, and  prevent the  injection from coagulating too  soon.
For this purpose it is necessary to place the animal, or part to
be injected, in warm water, as  hot as the operator's hand will
bear.  This should be kept at nearly the same temperature for
some time  by occasionally adding hot water.   The length of
time required is  in proportion to the size of the part, and the
amount of its rigidity.   Ruysch (from whom the art of inject-
ing has been called the Ruyschian art,) recommends a previous
maceration  for a day or two in cold water.
                            12* 
138
THE  MICROSCOPIST.
  When the size and the subject have both been properly pre-
pared, have the injection as hot as the finger can well  bear.
One of  the pipes, G, Fig. 43, must then be  placed in the
largest  artery of the part, and securely tied.  Put the 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.
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.
   As  the method of injecting  the minute  capillaries with
coloured size is often attended with doubtful  success, various
other plans have been proposed.   Ruysch's method, according
to  Rigerius, was to employ melted  tallow, coloured with ver-
milion,  to which, in  the summer, a  little  white  wax  was
added.
    Mr.  Rauby's material, as published by Dr. Hales, was resin
 and tallow, of each two ounces,  melted and strained through
 linen;  to which was added three ounces of vermilion, or finely
 ground indigo, which was first well rubbed  with eight  ounces
 of turpentine varnish.
    Dr.  Monro recommended coloured oil of  turpentine for  the
 small vessels, after the use of which he threw in the common
 coarse  injection.
    Professor Breschet frequently employed  with success milk,
 isinglass,  the alcoholic  solution of gum-lac,  spirit varnish, and
 spirit of turpentine; but  he  highly commends  the colouring
 matter extracted  from campeachy,   fernambone,  or  sandal
 woods.  He  says, " The  colouring matter of  campeachy wood 
ON MINUTE  INJECTIONS.
139
easily dissolves in water and  in  alcohol; it  is so penetrating
that it becomes rapidly spread through the vascular networks.
The sole inconvenience of this kind of injection is, that it can-
not 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 pro-
cess,  was published  in the  Comptes Rendus,  1841,  as  the
invention of M. Doyere.  According to  this, an aqueous solu-
tion of bichromate of potass is propelled into the vessels;  and
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 colour.
  Dr. Goadby has improved  upon the process last named by
uniting to the chemical solutions a  portion of gelatine.  The
following is his formula, originally published in the London
Lancet, and again in the 31edical Examiner,  March, 1850.
  Saturated  solution of bichromate  of potash, 8 fluid ounces;
water, 8  ounces; gelatine, 2 ounces.
  Saturated solution of acetate of lead,  8 fluid ounces; water,
8 ounces; gelatine, 2 ounces.
  Dr. G. gives the following  remarks respecting this process  :
__" The majority of preparations, thus injected, require to be
dried,  and  mounted  in Canada  balsam.  Each preparation,
when placed on  a slip of glass, will  necessarily possess more
or  less of the coloured infiltrated  gelatine, (by  which, he
alludes to the gelatine, coloured by the blood, which, together
with the acetate of potash resulting from the chemical decom-
position, may have transuded through the coats of the vessel,)
which, when dry, forms, together with the different  shades of 
140
THE  MICROSCOPIST.
the chromate of lead, beautiful objects, possessing depth and
richness  of colour.   The  gelatine also separates  and  defines
the different  layers of vessels.   By this injection the arteries
are always readily distinguishable by the purity and brightness
of the chromate of lead within them, while the veins are de-
tected by the altered colour imparted by the blood.
   "Those preparations which require to be kept wet,  can  be
preserved perfectly in my B  fluid—specific gravity  1-100;
the A fluid destroys them.
   " I would recommend, that the  slips of glass employed for
the dry preparation be instantly inscribed  with the name of
the preparation, written with a  diamond, for, when dry, it is
very difficult to recognise  one preparation from another, until
the operator's eye be  educated to  the effects of this 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.
   " The  bichromate of potash is greatly superior in colour to
the chromate, which yields too pale a yellow; and subsequent
experience has convinced me that the acetate  of potash  fre-
quently effects its liberation by destruction of the capillaries,
and this, even long after the preparations have been mounted
in Canada balsam; perhaps this may be owing to some chemical
action of  the acetate of potash upon them.
   " I would  suggest  the  substitution of the nitrate for the
acetate of lead, as we should then  have, in  the  liberated
nitrate of potash, a valuable auxiliary in the process  of pre-
servation.
   "Although  highly  desirable, as  the demonstrator  of the 
ON MINUTE  INJECTIONS.
141
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 mis-
lead 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 potassae  would have answered this purpose better.
   "When size injection is to be employed, coloured 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  colouring matter.
Hence the difficulty of procuring good injections of the human
subject.
   "But with the 'chemico-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-
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 plan has been suggested (as I am informed)
by  Dr.  Goddard of Philadelphia.  It   consists  in adding  a
quantity of sulphuric  ether  to the  finely levigated colouring
matter,  which is also first ground or  mixed with linseed oil, in
the manner employed by painters.   Upon this plan (as well as
upon the last-named) I have succeeded in  making some beau-
tiful injections of the  smallest capillaries, yet I  have  some-
times failed, owing to the too rapid  evaporation of the ether,
and the clogging  up of the vessels from the early deposition of
the solid colouring matter.  Perhaps a solution of gum mas- 
142
THE  MICROSCOPIST.
tich, &c, in ether, coloured with fine vermilion, &c, will answer
the indications better.
   A foetus may be injected by the umbilical vein; a uterus,
by the hypogastric arteries; the  head,  by the carotids;  the
liver, mucous membrane of the  intestines, &c, by the portal
vein; an extremity, by the principal artery; &c.
   Many parts, after injection, require to be macerated in water,
or corroded by dilute muriatic acid, &c, in order to exhibit the
ramifications  of the small vessels.   They should be very 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 coloured  material, on  account of the mercury  fre-
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
coloured  wax, mixed with nut-oil,  for the injection. 
CHAPTER  XII.
      EXAMINATION  OF  URINARY  DEPOSITS.

  The chemical composition of the urine and urinary deposits
has within a few years past attracted much attention, and  has
contributed much to our  knowledge  respecting the nature of
diseases and their diagnosis. To examine these, the microscope
is often an essential instrument.
  Deposits of uric acid and  its  combinations (called red, or
yellow-sand sediments), occur  in fever; in acute inflammation;
in rheumatism; in phthisis;  in  all the grades of dyspepsia;
in all or  most stages  of diseases  attended with arrest of 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 
144
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 neighbouring 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 re-
mainder  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, how-
ever, it is necessary to use high powers, a  drop of the sediment
should be placed on a glass slide and covered with thin glass.
   If  it is desired to  mount the object for future  examination,
it can be covered, when dry, with a drop of Canada  balsam,
and surmounted with the thin glass.  Very transparent objects
should be kept  in fluid, as weak spirit, water  saturated  with
creasote, or Goadby's fluid.
   Healthy Urine  holds in solution a variety of substances,
both organic and inorganic.   Chemists have not yet succeeded
in insulating all its ingredients  for examination, but the most
important of its solid materials are  urea, uric acid, hippuric
acid,  vesical mucus  and epithelial  debris, animal  extractive,
ammoniacal salts, fixed  alkaline  salts, and earthy salts. 
      examination of  urinary deposits.   145

  The amount passed by an individual during each twenty-four
hours, varies from twenty to fifty ounces, holding in solution
from  six  hundred  to  seven  hundred grains of solid matter.
When kept for some time it gradually becomes  turbid, and de-
posits a sediment  of earthy phosphates,  previously  held in
solution  by the slight  excess of acid present.  If  kept still
longer, it gradually putrefies, and, becoming concentrated by
evaporation,  deposits small  crystals of chloride  of sodium,
phosphates, and other salts,  and eventually becomes  covered
with a grayish-coloured mould.
   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 crystals of oxalate of urea  thus
obtained, a, Fig. 44, should be dissolved in hot water, and the
solution treated with  pulverized chalk as long as effervescence
is produced.   The urea remains in solution, and may be 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. 44, by
concentrating urine to about one-half its bulk, and  adding an
equal quantity of nitric acid.  If urea be suspected in excess,
a drop of the urine, without concentration, may be  treated with
nitric acid under the microscope.
  The proportion of uric acid in the healthy secretion varies
from 0-3 to 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
                             13 
146               THE  MICROSCOPIST.

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

                           Fig. 44.
  Hippuric Acid  is generally present in a small quantity in
healthy urine, and in certain forms of disease, especially where
a vegetable diet has been adopted.   Fig. 45 represents some
Fig. 45.
of its forms;  a are  deposited from an alcoholic solution, and
b 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  OF URINARY DEPOSITS.   147

may be examined with  the microscope, when the tufts will
probably be seen, coloured 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 coloured than usual,  a large proportion  of
what is termed  extractive, consisting  of colouring 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 kinds of fever, it
increases considerably.
   Fixed Alkaline  Salts may be obtained by incinerating the
evaporated residue  of urine, when a white  ash  will  be left,
consisting of a mixture of alkaline  and  earthy salts;  the 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.  46.  The cross- 
148
THE  MICROSCOPIST.
lets consist of chloride of sodium; the more plumose crystals
are probably phosphate of soda.

                           Fig. 46.
   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.
   When urinary deposit is examined with the  microscope,  it 
       EXAMINATION  OF  URINARY  DEPOSITS.   149

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. 47.  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 Na 03), 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
colour, owing  to the formation of murexide (C^ N5 H6 08).
                            13* 
150               THE  MICROSCOPIST.

  The crystalline forms of uric acid are various, but appear to
be modifications of the rhombic prism.
Fig. 47.
  Fig. 48 represents some of its forms.
  Oxalate of Lime often exists in the form of minute octahe-
dral crystals, varying  from  yjoth to -g-gV^th of an inch in
diameter,  a, Fig. 49.   When allowed to dry on the glass, each 
      EXAMINATION OF URINARY DEPOSITS.   151




crystal appears under the microscope like a black cube, having
Fig. 48.
in the centre a small white square opening, as  shown at b. 
152
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. 49.
assumes the forms  represented at c, more or less resembling
dumb-bells.*   This form, like the crystals of uric acid, the

  * Dr.  Fricke,  in the American Journal of Medical Science, July,
1850, states as his opinion that the dumb-bell  forms of crystals are
not oxalate of lime, but  disintegrated crystals of uric acid. 
examination of URINARY DEPOSITS.   153
triple phosphate, &c, is beautifully coloured when examined
by polarized light; the octahedral variety has little or no effect
upon it, being  invisible, or nearly  so, when the field is dark.
If the " dumb-bells" are kept in liquid for any length of time,
they gradually pass into octahedra.
  As the crystals of oxalate of lime are very transparent, and
about the same specific gravity as the urine, they may readily
escape detection,  unless some considerable  time is allowed for
deposition, or the urine is passed through a filter.
  Oxalate of lime is  insoluble  in water, in  acetic and oxalic
acids, and in  solution of potash; but it is  readily soluble in
dilute nitric and  hydrochloric acids.
  Cystine has occasionally  been found as a crystalline deposit
and in the form of small calculi.   It may be distinguished by
being insoluble, or nearly so,  in water  and dilute  acids, but
soluble in ammonia, from which small hexagonal crystals are
deposited on evaporation.  The usual microscopic appearance
is represented at  a, Fig.  50.  At b is the form left from the
ammoniacal solution.
                           Fig.50.
o   ®
  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 mag-
nesia.   It is thrown down, together with the triple phosphate 
154               THE  MICROSCOPIST.
(before noticed), on the addition of ammonia.   The crystalline
shape of the triple  phosphate,  however, readily distinguishes
it under the microscope from the amorphous particles of phos-
phate of lime with which it is usually mixed.  The  earthy
phosphates are readily soluble in dilute acids,  from which they
are precipitated by ammonia. They are insoluble in a solution
of potash.
   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
perceived with the microscope.  In such cases, the urine may
be agitated with a little ether, which will dissolve the fat, and 
       EXAMINATION  OF  URINARY DEPOSITS.   155

the solution so formed will separate  from the watery liquid,
and form a distinct stratum on the surface.
   Chylous 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 colourless 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  appear-
ance 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 proba-
bly be  entangled in  the coagula, and may  be  forced out by 
156
THE  MICROSCOPIST.
gentle pressure  under a  strip of thin  glass.  If there is no
coagula, the liquid may rest for a short time, and a drop  from
the  bottom  examined.   The urine may  also  be tested for
albumen after separating the solid matter by filtering.  When
the colouring matter of the blood is present, it will coagulate
with the albumen, giving it a red or brown colour.  When the
fibrin, in  its  soluble form,  is present,  it usually coagulates
spontaneously on cooling, causing the urine  to become gelati-
nous.  The coagulum of fibrin, when pressed between glasses,
is  generally composed of minute amorphous particles, with a
few  red blood corpuscles, quite  different from  the  granular
mucus corpuscles,  for which it  might be mistaken without
microscopic examination.
   Bile or purpurine in  urine has  nearly the  same colour as
when blood is present; hence, unless the blood corpuscles are
present, we should apply the tests for the detection  of those
substances before finally deciding.  Purpurine will be  dissolved
by treating with warm alcohol, or may be precipitated by add-
ing a little warm aqueous solution of urate of ammonia, which
on cooling will fall down, carrying with it the  colouring  mat-
ter.   Bile  may be tested by  pouring a few drops of urine on a
white plate, and adding  carefully a drop or two of nitric acid.
When bile is present in any considerable quantity, the liquid
becomes  successively pale-green,  violet,  pink, and  yellow, the
colour rapidly changing  as  the  acid  mixes with the urine.
When only slight  traces of bile  are present, the urine should
be concentrated  by evaporation.
   When semen is  present in urine, it may easily be  detected
under the  microscope, by the appearance of  minute 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.   157

  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 phosphates, 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-coloured
granular powder.
  Moore s Test is made by mixing a little suspected urine with
half its volume of liquor  potassae 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 bv which it becomes  converted into alcohol and carbonic
      J                       14 
158
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. 51, which, in

                          Fig. 51.
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 3Ianuals of
Drs. Golding Bird, Griffith, 3Iarkwick, and Rees.  The works of
the latter three gentlemen have been published in Philadelphia,
in one convenient volume.  The " Analysis"  of Dr.  Rees con-
tains  also a valuable  essay on the  treatment of urinary dis-
eases. 
      EXAMINATION  OF  URINARY  DEPOSITS.   159


                        TABLE  I.
FOR  THE  CHEMICAL  EXAMINATION  OF  URINARY
                        DEPOSIT S.
   1. The sediment  dissolves when warmed.    Urate  of Am-
monia.
   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,
hexagonal crystals.   Cystine?
   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. 
 160               THE  MICROSCOPIST.

   3. Precipitate  formed  on boiling;  soluble in nitric  acid.
 Excess of Earthy Phosjjhates.
   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.  Ilippuric Acid.
   If the  urine is  highly coloured,
   7. Dark coagulum formed on boiling.   Blood?
   8. Red colour with hydrochloric acid.   Excess of Colouring
 Matter.
   9. Pink precipitate with warm solution of urate of ammonia.
 Purpurine.
   10. Change of  colour with nitric acid.  Biliary Matter.


                       TABLE  III.

  FOR  MICROSCOPIC  EXAMINATION OF DEPOSIT.

                       If Crystalline.

  1.  Lozenge-shaped, &c.   Uric Acid.
  2.  Stellae, or three-sided prisms (after  saturating  with am-
monia).   Triple Phosp>hate.
  3.  Octahedra, or dumb-bells.   Oxalate of Lime.
  4.  Rosette-like tables.   Cystine.

                       If Amorjilious.

  5.  Soluble when warmed.  Urate of Ammonia.
  6.  Soluble in acetic acid.  Phosphate of Lime.
  7.  Yellowish grains.  Urate of Soda? 
    EXAMINATION OF URINARY DEPOSITS.    161

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.
14* 
CHAPTER XIII.
            ON POLARIZED LIGHT.

  " If we transmit," says Dr. Brewster, " a beam of the sun's
light through a circular aperture into a dark room, and if we
reflect it from any crystallized or uncrystallized body, or 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 colour.
  " The same property belongs to light emitted from a candle,
                    Fig. 52.
                       O.o.       E.c.




        <3XDO
            B       B'
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.
163
be a circle, like A, B, C, D, Fig. 52, and we shall distinguish
the section of a beam of common light  by a circle with two
diameters, AB, CD, at right angles to each other.
   "If we now allow the  same beam of light to fall upon a
rhomb of Iceland  spar, as in  Fig. 53, and examine the two
Fig. 53.
circular beams, 0 o, E e, formed by double refraction, we shall
find,
   " 1. That the beams 0 o, E c, have different properties on dif-
ferent sides; so that each of them differs, in this respect, from
the beam 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. 52;
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, Oo, Ee, Fig. 53, 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,  O o, E e, Fig. 53, to  be united  into  one, we  obtain a
beam which has exactly the same properties as the beam A, B,
C, D, Fig. 52,  of common light.  Hence we infer, that a beam 
164
THE  MICROSCOPIST.
of common  light  consists of two beams  of polarized  light,
whose  planes of polarization, or whose diameters of similar
properties, are at right angles to one another."
  There are other 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. 54, represent

                            Fig. 54.
two tubes, one turning within the other.   A, B, are plates of
glass capable of turning on their axis, so  as to form different
angles with the axis of the tube.
   If a beam of light, r s, from a candle or hole in the 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,
will become brighter and brighter till the tube has been turned
round 90°, when the plane of reflection from B is coincident with 
ON POLARIZED LIGHT.
165
or parallel to that from A.  In this position the reflected ray, E,
is brightest.   If the tube be turned again, the light will grow
more and more faint, until another 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. 55,  to pass through bundles of glass  plates, A, B, in-

                           Fig. 55.

                 &-JWL   Ml
                   ^Mm—md-ip

clined at the proper angle.  If the bundle  of  plates, B, be
placed as in the figure,  the ray,  s t,  polarized by  passing
through the bundle,  A, will be  incident on B  at the polarizing
angle, and not a particle will be reflected, but it  will be 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 each quadrant, as in the former case.
For the ray passing  through the  tube  in Fig. 54, or the ray,
s t, in the last figure, we may substitute  one  of  the polarized
rays formed  by double  refraction  in a rhomb  of  Iceland spar,
as seen  in Fig. 53,  or we  may  employ with even greater  ad-
vantage the  single image prism  of 3Ir. Nicol,  who employed a
rhomb of  calcareous  spar divided into two equal portions,  in a
plane passing through the acute lateral angles, and nearly
touching the obtuse solid angles. The cut surfaces having been
carefully polished, were then cemented together with  Canada 
166
THE  MICROSCOPIST.
balsam, so  as  to  form a rhomb  of nearly the same size  and
shape as it was before cutting.
  By this arrangement, of the  two rays into which a beam of
common light would be separated, only one is transmitted, the
other being rendered too divergent.   Two of these prisms form
the usual polarizing apparatus of the microscope, being used in
the same  manner as the bundles of  glass plates, Fig. 55, just
described.  One of the prisms is adapted to the under surface
of the stage, and  is called  the 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 colour be not
objectionable, it  may be  used  to advantage,  as the field  of
view is not so much contracted as when a prism is used.   A
tourmaline of a neutral tint is  an excellent analyzer.
   The splendid colours,  and systems of coloured  rings, pro-
duced  by  transmitting polarized light through transparent
bodies  that possess double refraction, are the  most brilliant
phenomena that  can  be exhibited.  They were discovered
simultaneously by M.  Arago and Dr. Brewster.
   To see these colours:—having the polarizing apparatus  so
placed that no light can be seen through it, place  a thin film
of mica or sulphate of lime (between the twentieth and fiftieth
of an inch thick), so that  the polarized beam may pass through
it perpendicularly.  It should be placed between the polarizer 
ON POLARIZED  LIGHT.
167
 and the 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 colours.  If the film be turned
 round, still keeping it perpendicular to the polarized ray, the
 colours will become less or more bright, and two positions will
 be found, at right angles with each other, wherein no colours
 at all are perceived.  If the analyzer be turned round, the film
 retaining its position,  complementary colours will  alternate,
 together with points of invisibility, during each revolution.
  The colours of the film vary with  its thickness, so that by
 making grooves or lines of various depths, the most beautiful
 patterns may be  produced.  Drawings of figures  and  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 colours.
  Various crystals exhibit, round their axes of double refrac-
 tion, beautiful systems of coloured rings, often intersected by
 a black cross.   Complementary colours may  be  produced  in
 them by  turning  round  the analyzer.  In large  crystals,  as
 rhombs of Iceland spar, certain angles must be ground down
 and polished in order to exhibit the rings.
  In  those crystals having two axes  of  double  refraction, a
 double system of rings  will  be seen.   A transverse  section of
a prism of nitre will exhibit this phenomenon.
  The great advantage of employing the microscope in viewing
the colours of crystals, &c, by polarized light, arises from the
fact  that, when crystallized on  a slip of glass, many of the
small crystals will  be arranged with their axes of double  re-
fraction  in  the  direction of the polarized beam.   All such,
therefore, will exhibit colours, as will those also in which the
thickness of the crystal is not below the proper standard. 
168
THE  MICROSCOPIST.
   After the polarizing  apparatus  is  adjusted, as before 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.   31any  animal
structures, as feathers, slices of quill, horn, &c, are best shown
by placing a film of selenite or mica beneath them, by which
they become intensely  coloured.   If  the  film  be  of  unequal
thickness, the colours will vary.
   "The application," says Mr. Quekett, "of  this modification
of light to the  illumination of very minute structures has not
yet been fully carried out, but still there  is  no test of 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,
&c, to preserve them from injury by the pressure of the glass
cover), or in Canada balsam.  If it be desired to examine the 
ON POLARIZED  LIGHT.
169
crystals during their formation,  the crystallization should  be
carried on in a glass that is  slightly concave.   All those crys-
tals that are so thin as not to exhibit colour, may have colour
given them  by placing a film of mica  or selenite  under them
on the stage of the  microscope.
  According to Mr. Fox Talbot, who first  applied the 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.
15 
CHAPTER  XIV.
   MISCELLANEOUS  HINTS  TO  MICRO SCOPISTS.

  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 pre-
serve  it  from  dust  and damp; the  former will  scratch  the
glasses, and the latter  will prevent you from wiping them
clean.  As to  the  object-glasses, endeavour to  keep them as
clean as possible without wiping, and merely use a camel's-hair
pencil to brush them with; for wiping them hard with any-
thing 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 how-
ever perfect it may be, if there is the least light reflected from
the mountings of the glasses, or within the tubes, the fog and
glare produced will materially deteriorate their performance;
it is  therefore necessary that all their surfaces be made  as
sombre as possible.   The usual method of effecting this is  to 
  MISCELLANEOUS  HINTS  TO  MICRO SCOPIST S. 171

cover the parts while hot with a black lacquer, made by mix-
ing lampblack 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 platinum);  after remaining  on  the work  a  few
minutes it  is wiped  off,  the  surface having  assumed a deep
brown or black colour.  If these are not at hand, a  strong
solution  of muriate of ammonia will answer  for temporary
purposes.   Another method of stifling false light is by stops or
diaphragms in the body of the instrument; these have already
been referred to.
  Cabinet for Microscopic Objects.—The author of "Mi-
croscopic  Objects" recommends  a  cabinet with shallow draw-
ers—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 sliders meeting in the middle of the
drawer are kept down by a very thin slip of wood covered with
velvet.  In this way the sliders do not shake when the cabinet
is moved  from place to place;  every object is seen without
removal, and no loss of time is occasioned in making a selec-
tion.
  Some persons have their sliders arranged edgewise, in boxes
made in imitation of books; the ends of the  sliders being held
by a sort of rack. This may sometimes be convenient, but the
other form is preferable.
  Brewster's Method of  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 
172
THE  MICROSCOPIST.
 illuminating apparatus should be perfect, than that the magni-
 fying one should be so;  and the essential part of his method
 consists in this :—That the rays which form the illuminating
 image or disc shall have  their foci exactly on the part  of the
 microscopic  object to be observed, so that the illuminating
 rays may radiate as it were from the object, as if it were lumi-
 nous.  Now this can only  be well attained  by illuminating
 with a single lens, or a system of lenses, without spherical or
 chromatic aberration, whose focal length, either real or equiva-
 lent, is less than the focal length of the  object-glass  of the
 microscope.  The smaller the focal length of the illuminating
 lens, or system of  lenses,  the more  completely do we  secure
 the condition that the illuminating rays shall not  come to a
 focus, either before they  reached the object, or after they have
 passed it.
   Mode of Obtaining the  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 de-
 cayed portion with a piece of wire, and substitute a fresh sup-
 ply.  A much greater number of animalcules are raised  by the
 sage leaves; but I have sometimes been obliged to discon-
tinue 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. 173

ter, and of four and a half inches focus, silvered on the plane
side, and backed with a plate  of brass.   This  lens, when so
treated, becomes a reflector of about two and a quarter inches
focus, and forms one of the best  instruments that can be de-
sired for throwing light upon an object viewed as opaque.  We
have used such an arrangement for some  time in place of the
concave mirror, and deemed it peculiar to ourselves till reading
an account of the above.
  Apparatus  to Prevent the  Evaporation of Liquids
under the Microscope.—Vapours 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.
                           15* 
    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.
	MUCUS PRODUCED BY NOR-MAL Irritation.	MUCUS PRODUCED BY	MUCUS PRODUCED BY A	MUCUS PRODUCED FROM
Healthy Mucus.		slight normal Inflam-	MORE INTENSE NORMAL	CHRONIC NORMAL IN-
		mation.	Inflammation.	FLAMMATION.
Very few globules	Very few globules	Globules more nume-rous	Globules very nume-rous	Globules very abundant
Much of an amorphous	Very much of proper	Less mucus	Much less mucus	Very little mucus
substance (proper	mucus			
mucus)				
Contains but little epi-	Contains but little of	Contains more epithe-	Contains very little epi-	Contains very little epi-
thelium	epithelium	lium	thelium	thelium
Globules from 2-4 times	Globules from 4-5 times	Globules 6-8 times lar-	Globules from 6-8 times	Globules 6-8 times lar-
larger than the blood	larger than the blood	ger than the blood	larger than the blood	ger than the blood
pai tides	particles	particles	particles	particles
No molecules, or the	The smallest molecules	The smallest molecules	Filled with the small-	Filled with the small-
smallest, fill the glo-	fill the globules	(filled with), and a	est molecules and a	est molecules and a
bules		central vesicle	central vesicle	central vesicle
Very thin envelope to	Very thin smooth en-	Smooth envelope	Smooth envelope	Smooth or no envelope
the globules	velope			
Not changed in water	Globules swell in dis-tilled water	Swell in distilled water	Globules swell in dis-tilled water	Swell in distilled water
		Envelopes easily broken	Envelopes easily^broken	Envelopes easily broken
		in water		
 
MUCUS PRODUCED FROM SPECIFIC OR ANOMALOUS INFLAMMATION CONTAINS, BESIDES SUBSTANCES PECULIAR TO

                                         NORMAL MUCUS, OTHER FORMS.
MUCU8 GENERATED  FROM TUBERCULOUS IN-
        FLAMMATION OP THE LUNGS.
Besides  the products  of catarrhal in-
  flammation contains yellow  lenticular
  spheres 1-8 times  larger than  the glo-
  bules  of pus,  concentrically striated,
  composed of concentric lamella:, which
  are dissolved in caustic potash
                      f They are in-
In nitric acid          | creased 5 times
— solution of nitrate of \ in  volume and
    silver             | become transpa-
                      rent
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 intlamma-
  tion
Mucus of urethral blennorrhoja.
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 all 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.
				PUS FROM THE SURFACE OF
PUS FROM A RECENT WOUND.	PCS FROM A RECENT ABSCESS.	PUS FROM AN OLD ABSCESS.	PUS FROM AN OLD WOUND.	AN ORGAN WHOSE CONTI-NUITY IS UNINJURED.
Few globules	Many globules	Many globules	Fewer globules	Fewer globules
Contains more fluid	Contains but little fluid	Contains but little fluid	But little fluid	Much fluid
Globules from 4-6 times	Globules 3-4 times larger	Globules 3-4 times larger	Globules 3-4 times larger	Globules 6-8 times larger
larger than those of	than those of the blood	than those of the blood	than those of the blood	than those of the blood
the blood			Contains a good deal of epithelium	Contains but little epi-thelium
With very small, and lar-	With very small, and lar-	With very small, and lar-	With very small, and lar-	With very small and lar-
ger molecules	ger molecules	ger molecules	ger molecules	ger molecules or none
Have one central vesicle	One or two central vesi-	With a central vesicle	No central vesicle	Composed of a central
and an envelope	cles, seldom without one			vesicle full of molecu-les, or none at all in it
Globules swell, and en-	Globules swell, and en-	Swell but little in dis-	Does not swell in dis-	Sometimes swell in dis-
velope bursts in dis-	velope broken in dis-	tilled water	tilled water	tilled water
tilled water	tilled water			
 
PUS FROM  SPECIFIC INFLAMMATION.
1. Generated during the Variolous Process.
During the formation of
      papule.
During the formation  of
      vesicles.
During the formation of
      pustules.
2. Generated in the Tuber-
      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
  globules 2-3 times larger than
  those of the blood
Filled with the smallest mole-
  cules
Molecular motion scarcely to be
  seen
Animalculas 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 5th 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
See—Mucus produced  from
   Specific Inflammation.
                                                          On the 6th day the thicker yel-
                                                            low  fluid  has but  a slight
                                                            alkaline 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  con-
                                                            tains many globules adhering
                                                            together
                                                          The  envelopes are  very easily
                                                            broken, the molecules  dissi-
                                                            pated without order
                                                          Cells of epithelium and  drops
                                                            of fat are frequently seen in
                                                            it
N.B.—In some individuals the globules are 3-4 times larger than those of the blood, perfectly or partly empty, also spheres
                    twice or six times larger than the pus globules, consisting of smaller spherules. 
                                          C.   OF SEROUS  EXUDATION.

WHITE, OR GREENISH-WHITE, LIMPID, EXUDATED, SEROUS  FLUID IS COMPOSED OF A PELLUCID FLUID AND GLOBULES.
Serous Exuda-	Serous Exuda-	Serous Exuda-	Serous Exuda-	Serous Exuda-	Srrous Exuda-	Skrous Exuda-	Serous Exuda-
tion OF A BLAD-	tion from crude	tion EXTRICATED	tion EXTRACTED	tion FROM A HY-	tion FROM C3DE-	tion EXTRACTED	tion FROM THE
DER PRODUCED BY	infiltration of	FROM THE PAPU-	FROM THE FI-	DR0CYST.	MA OF THE CUTIS.	FROM THE SUB-	VAGINAL DIS-
BLISTER.	INTESTINAL TY-	LM OF MODIFIED	ERINE OF A VIL-			STANCE OF AN IN-	CHARGE ON THE
	PHUS.	variola.	LOUS HEART.			FLAMED HUMAN PLACENTA.	THIRD PERIOD OF PREGNANCY.
Contains white	Contains white	Contains white	Contains white	Contains per-	Contains white,	Contains white	Contains white
globules with	globules with	globules with	globules, con-	fectly round	or yellowish-	globules, with	globules, with
a very thin	an envelope	a very thin	sisting of a	white globules	white stella-	an envelope	an envelope
covering filled	filled with the	coveiing filled	very thin en-	destitute of	ted globules,	filled with the	filled with the
with the small-	smallest mole-	with the small-	velope, filled	molecules	scarcely larger	smallestmole-	smallest mole-
est molecules,	cules	est molecules	with the small-	Scarcely larger	than those of	eules	cules
or destitute of	1-2 larger than	1-4 times larger	est molecules	than the glo-	the blood	1-2 times larger	Once to twice
all covering	the blood glo-	than the blood	1-2 times larger	bules of the	Here and there	than those of	larger than
1-2 larger than	bules	globules	than those of	blood	provided with	the blood	the blood discs
the blood glo-			the blood		a small nu-		
bules					cleus		
D.  THE MORPHOLOGY OF THE  GLOBULES GENERATED DURING  THE  PATHOLOGICAL PROCESS.

                                  1.  THOSE WHICH OCCUR IN MUCOUS MEMBRANE.
In healthy mucous mem-
        brane.
Very few yellowish-white
  globules are  generated
  provided with a cover-
  ing, and enclosing none
  or very few of the small-
  er moleules
They are not changed in
  water, and are from 2-4
  times larger than those
  of the blood
IN IRRITATED MUCOUS
     MEMBRANE.
Very few yellowish-white
  globules are  generated
They  are  provided with
  an envelope, enclosing
  the smallest molecules,
  and are 4 times larger
  than the blood globu-
  les, and  swell in water
In slightly irritated mu-
    cous MEMBRANE.
More copious or abundant
  yellowish-white  globu-
  les are generated. They
  are  provided  with an
  envelope, 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
In a more intense inflam-
  mation OF MUCOUS MEM-
  BRANE.
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
In CHRONIC INFLAMMATION
 OF A MUCOUS MEMBRANE.
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
  smallest molecules, and
  a central vesicle 
2. THOSE WHICH ARE GENERATED IN THE SKIN.
BY THE  APPLICATION OF A
        BLISTER.
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
BY THE VARIOLOUS PROCESS
 UNDER THE FORMATION OF
 PAPULE.
A very few white globu-
  lus, 2-3  times larger
  than those of the blood,
  pellucid, endowed with
  a very thin  covering,
  enclosing the smallest
  molecules
They swell in water
BY THE VARIOLOUS PROCESS
 DURING THE FORMATION OF
 VESICLES.
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
By THE VARIOLOUS PROCESS
 DURING THE FORMATION OF
 PUSTULES.
Very  numerous  yellow
  globules, 4-5 times lar-
  ger than  those of the
  blood,  provided  with
  the smallest and larger
  molecules, and the cen-
  tral vesicle
They swell in water, and
  are easily broken
BY THE VARIOLOUS PROCESS
 DURING THE FORMATION OF
 CRUSTS.
A few yellow whole glo-
  bules, 4-5 times larger
  than those of the blood:
  many  lacerated,   fur-
  nished with  no enve-
  lope, or with one  filled
  with the different mole-
  cules
They are easily broken
3. THOSE WHICH ARE GENERATED IN SEROUS MEMBRANE.
White, pellucid, perfectly
 round globules are form-
 ed, scarcely larger than
 those of the blood, with
 an envelope destitute of
 all molecules
They are not changed in
 water
OF THE PERICARDIUM UNDER
  THE  FORMATION OF THE
  VILLOUS HEART.
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
OF AN INFLAMED PERITO-
        NEUM.
OF AN INFLAMED PERITO-
    NEUM NEONATI.
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
  Of a very acutely
inflamed peritoneum.
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.
OF 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 TYPHUS.
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 hut 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, are many mole-cules	Round 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-ing those of the blood, composed of an envelope, filled with the smallest molecules		Round 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 magnitude the globules of the blood, or twice as large, with or without an envelope, but if with one it is filled with the smallest molecules They are not changed by water			
 
THOSE  WHICH ARE GENERATED  ON  THE  SURFACE OF  A PATHOLOGICAL  (DISEASED)  ORGAN.


                                           EXP 0 SED.
IN THE TENTH HOUR OF A RECENT
           WOUND.
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
Of pus of A RECENT  WOUND 24
      HOURS AND BEYOND.
Round  yellowish-white  abun-
 dant globules 4-0 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___________
OF PUS IN THE SEVENTH WEEK OF
       A RECENT WOUND.
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
From an old wound suppurating
         but little.
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
ABSCESSUS IDIOPATHIC! RECENTIS-
    SIMI PRELI ABDOMINALIS.
Round 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
OF IDIOPATHIC ABSCESS OF THE
           LIVER.
Round  yellow  globules  3-4
 times larger than those of the
 blood, composed of a thin enve-
 lope full of the  larger and a
 few of the largest molecules
They are changed but little in
 water
Of an old idiopathic abscess.
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
Op a metastatic abscess of six
       days' standing.
Round globules 1-3 times larger
 than  those of the blood,  com-
 posed of the smallest molecules,
 but seldom of an envelope
Are not changed by water 
COMPARISON BETWEEN MUCUS AND  PUS GENERATED  FROM NORMAL INFLAMMATION.
	si PS >J o a		p o o	►J k r.	< s gg	o	3 Eg M ** a	<	Q o < 3 « o	< 9 OS S ■«! ^	B < H X	3	2 £ S p f. ID o W o	g H 5 « <* 2 f- H p* r* b-P * 5 Q O W o g	< gg p. « <	a H n is H s 3	K <l o Hi H P4 & ft.	o s £ ft.
	Round	6-8	White	Smooth	Single	The	I'luve-	Dis-	Dis-	Quick-	Corru-	Corru-	Corru-	First	No	No	Dis-	Con-
i		times	or		or	verv	lopes	solves	solves	ly dis-	gates	gates	gates	dis-	change	change	solves	tracts
1		larger	vellow		double	small	are	the en-	the en-	solves	the en-	the en-	the glo-	solves			the	the
&		than				and	broken	velopes	velopes	the en-	velopes	velopes	bules,	the en-			globu-	globu-
K 1		those				the		and the	and	velopes,			and	velopes,			les ;	les
3 1		of the				larger		very	the	the			tinges	more			the	
		blood						small	very	white			them	slowly			white	
								mole-	small	vesicle			of a	the			mu-	
o <f								cules.	mole-	remain-ing			yellow	very			cous	
o |								_	cules.				colour	small			fluid	
" 1								The nuclei						mole-cules			re-mains	
f								1-6 re-						and				
I								main						nuclei				
1								clearly		i								
\								) to be										
-3 >•								seen										
3		|			I			No | No		No	fcorms	Forms'		Forms			,	
-z • . (								change) change		change	fila-	fila-		fila-				
S.S s I	J							pro- , pro-		pro7	ments	ments		ments,				
■g£.2\	|							duced duced		duced				which				
£-,£>														are				
																		
														more				
alaj														slowly				
														dis-				
o or														solved				
<N CO \	1				1									in it				
 
182
THE  MICROSCOPIST.
•3NIA1 ao siiHias	Con-tracts the globu-les, and forms from 1-5 nuclei	
■HSvioa sana	Dis-solves the glo-bules, the mu-cous fluid remain-ing	
•aaxvAV awn	.a	
•vinonkv aand	£ a	
•H3A1IS ao aivaimao'ios aaivHi.MaonpD	Ren-ders the glo-bules trans-parent, the con-tracted nucleus remain-ing	Forms 1 Forms 1 Forms nofila- no fila- no fila-ments ments ments
•aaAiis ao aXVUIIM 3HI ao NOIIMOS	Corru-gates the globu-les, and gives them a yellow tinge	
•aiov onviann	Corru-gates the enve-lopes	
•aiov OIHILS	Corru-gates the enve-lopes	sis o o 2 fe a a
•aiov OIHVIHVI	Very quickly dis-solves the enve-lopes	Pro-duces no change
•aiov onvxo	Dis-solves the en-velopes, the 2-5 nuclei remain	Pro- 1 Pro-duces duces no no change [change
•aiov onaov	Dis-solves the en-velopes, the 2-5 nuclei remain	
•aaivAV aaiiusia	Enve-lopes are bro-ken	
•sainoaiow	The very small and the larger	
•310IS3A 1VUIN33	One or two, sel-dom none	1
•aaoiaAxa	Smooth or none at all	
•ano-ioo	White or yellow	
•aaniiNOvw	3-4 times longer than those of the blood	
•Bsinaoio am ao waoa	3 o a o u°	
      •pmg
ppnnad b jo 'Z
•sainqoTOJO'l
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INDEX.
                               a.
Achromatic object-glasses, their invention an epoch in histology, 18
                          description of, 34
Animal tissues, to be examined while fresh, 17
               on procuring, 73
Accessory instruments, 40
Animalcule cage, 37, 48
Asphaltum cement, 58
Agate, 64
Algae, 71
Aphides, 82
Acari, 82
Anatomical preparations, 85
Areolar tissue, .12
Artificial star, as a test object, 99
Angle of aperture, explained, 100
Arm rests,  107
Albuminous urine, 144, 157
Alkaline salts in urine, 147
Advantage of polarized light in examination, 168
Apparatus to prevent evaporation, 173
                                B.
Bog iron ore, from infusoria, 14
Borelli, his observations on pus,  &c, 15
Blood corpuscles, 85
 Blood discs of siren, 86
 Bone, 86
 Basement membrane, 92, 93, 116 
184
INDEX.
Bat's hair, 102
Branchial cartilage of tadpole, 120
Blood in urine, 144, 155
Bile in urine, 156
Brewster's mode of illuminating objects, 171

                               C.
Causes of error in observation,  15
Coal beds,  from vegetation, 14
Coddington lens, 29
Compound microscope, 31
                      defects of the common, 33
                      improvements in the, 33
                      mechanical conveniences necessary to the, 35
                      forms of the, 35
                      most celebrated makers of the, 36, 38
                      Smith and  Beck's, 36
                      efforts to reduce the price of the, 38
Condenser, 37, 40, 49, 50
Condensing (or bull's-eye) lens,  37, 42, 50
Camera lucida, 37, 45
Compressorium, 48
Cook's preserving fluid, 54
Cooper's preserving fluid, 54
Chloroform as a preservative, 56
Cells for mounting, 58
Cements, 58
Canada balsam cement, 59
Charring vegetable matters, 59
Carbonate of lime, 64
Crystallization of salts, 64
                 water,  65
Cuticles, 66
Cellular tissues, 67
Charcoal, 69
Circulation in vegetables, 72
Corals, 78
Circulation of blood,  86 
INDEX.
Capillaries, their functions, 95
           of skin, 89
           of mucous membrane, 94
Crystalline lens in fish, 90
Ciliary processes of the eye, 90
       movement, 94
Chromatic aberration, 33
                     mode of observing, 98
Circulatory system of insects,  112
Chemical constitution of organized bodies, 115
Cell-growth in a meliceritous tumour, 121
Classification of animal tissues, 121
                malignant growths, 127
Carcinoma, 129
Chemico-gelatinous injection by Dr. Goadby, 139
Cystine in urine, 153
Colours exhibited by polarized light, 166
Cleaning the glasses of microscopes,  170
Cabinet  for microscopic objects, 171

                               D.
Dissecting microscope  of Mr.  Slack,  27
Dark wells,  37
Diaphragm, 37, 40,  49, 51
Deut-ioduret of mercury,  65
Dissecting needles, 106
          troughs,  106
Digestive system of  insects, 111
Development of cells, 116
                animal tissues, 119
Diabetic urine, 144, 157

                                 E.

Erector, 36, 42
Entozoon folliculorum, 82
Epithelium, 92, 93
Examination of morbid structure,  124
                                 its importance, 126
                               16* 
186
INDEX.
 Encephaloid, 131
 Earthy phosphates in urine, 143, 148, 159
 Eyes qf animals, 90
                                F.
 Fossil remains determined by the microscope, 1 i
 Fontana, histological observations of, 17
 Frog plate, 46
 Fishing tubes, 48, 173
 Fossil wood, 69
 Ferns, 71
 Fibrous and areolar tissue, 92
 Forms of nuclei, 118
 Form of fibrous tumour, 127
                                G.
 Geology, use of microscope in, 13
 Goadby's fluids, 55
 Gum mastich cement, 59
 Gannal process, 54
 Glycerine, 54
                               H.
 Histology, created by the microscope, 14
 Hewson on the blood globules, 17
 Herschell's doublets, 29
 Holland's triplet, 31
 Huygenian eye-piece, 34
 Hairs, down, &c, of plants, 69
 Hard tissues, 71
 Hair of animals, 85
 Horn, hoofs, quills, &c, 85
 Human blood, 86
 Hair of Dermestes, 102
 Hippuric acid, 146

                               I.
 Importance of the microscope to zoology, 14
Inorganic  objects, 64 
181
Illuminating lamp, 43, 50
Iron pyrites, 65
Infusoria, classification of, 74
          on procuring, 75
          to observe the structure of, 77
          fossil, 77
Insects, antennae of, 78
        eggs, 79
        elytra, 79
        eyes,  80
        feet, 81
        hairs, 81
        mouths, &c, 81
        parasitic,  82
        trachea, 83
        stings, ovipositors, &c, 83
        internal anatomy of, 109
Injected papillae of skin, 90
        preparations,  94
Instruments for minute dissection, 105
Internal anatomy of insects, 109
Injecting materials, 134, 137, 138, 141
Instrument for diagnosis of tumours, 133
Injection of the lymphatics, 142
                                J.
Japanner's gold size, 58


Kiestein, 144
K.
Lenses, different forms and effects of, 22
        simple mode of making, 28
        imperfections in, 29
Lewenhoeck, his discoveries,  16
Lieberkuhn, his anatomical researches, 17
            concave reflector,  so called, 44
Lamp-black cement, 59 
188
INDEX.
 Lichens and fungi, 72
 Loaded corks, 106
 Lepisma saccharina,  103
                               M.
 Malpighi, microscopic researches of, 15
 Modern observers, 19
 Medico-legal inquiries with the microscope, 21
 Micrometer eye-piece, 35
 Magnifying powers, hints respecting, 49
                   table of, 23
                   to obtain the power of a compound microscope, 46
 Mirror, use of the, 50
 Management of the light,  50
 Mounting transparent objects, 53
                            in the dry way, 53, 54, 61
                            in fluid, 57
                            in balsam, 59
 Marine glue, 58
 Mounting cellular structures, 60
          opaque objects,  61
          crystals for polarized light, 63, 168
 Mosses, 71
 Muscular fibre, 91
 Mucous membrane, 92, 93
 Mouse hair, 102
 Morpho Menelaus, 103
 Muscular system of insects, 113
 Morphology of pathological fluids, 133, 174
 Method of injection, by Ruysch, 138
                      Ranby,  138
                      Monro,  138
                      Professor Breschet,  138
                      M. Doyere, 139
                      Dr. Goddard, 141
Mucus in urine,  155

                               N.
Nervous structure, examination of, 91 
INDEX.
 Nerves and capillaries of muscle, 91
 Nervous system of insects, 112

                                0.
 Organic remains in limestone, 14
 Optical illusion to be guarded against, 17
 Opaque objects, mounting of, 61
                how viewed, 51, 52
                Mr. Brooke's mode of viewing,
 Oolites, 65
 Organic fibres, 72
 Oxalate of lime in urine, 143, 150,  159

                               P.
 Polarizing apparatus, 41
 Preparation of glass nlides, 54, 57
 Preserving fluids, 54
 Pollen, 69
 Pigment cells of skin, 89
         of the eye, 90
 Pontia brassica, 104
 Podura plumbea, 104
 Proximate principles, 115
 Primary form of organic matter, 115
 Pus in urine, 144, 155
    distinction between it and mucus, 125
 Polarization of light, 162

                               Q.
 Qualifications of a microscopist, 18

                               R.
 Religious  sentiment, microscope conducive  to, 1
Reflecting microscope superseded, 38
          a curious form of,  38
Rules for  microscopic observations,  49
Raphides, 71
Retina of the eye,  90
Respiratory system of insects, 109 
190
INDEX.
                               S.
Simple microscopes, construction of, 23
                   magnifying poAvers of, 23
                   mode of mounting,  23
                   form of, for opaque objects, 26
Stanhope lens, 29
Silver cup or Lieberkuhn, 37, 44
Side reflector, 37, 44
Stage micrometer,  46
Size of glass for mounting, 53
Sealing-wax varnish, 58
Sand, 65
Sections of granite, &c, 65
           coal, 65
           wood, 68
Siliceous cuticles, &c, 69
Starch, 70
Seeds, 71
Sponges, 78
Shells of mollusca, 83
Scales of fish, 84
Skin, 89
Spherical  aberration,  33, 99
Scales of insects, 103
Shells of infusoria, 104
Swammerdam's scissors, 105
               mode of dissection, 107
Secondary organic compounds, 115
Scrofulous growths, 127
Syringe for minute injection, 135
Stopping false light in microscopes, 170
Substitute for the concave speculum, 172

                               T.
Trough for chara,  &c, 36, 48
Thin cells for delicate tissues, 57
Teeth, 88 
INDEX.
191
Theory of life and sensation, 96
Test objects, Dr. Goring's discovery of, 98
             character of, 102
Tinea vestianella, 103
Tables for examination of urinary deposits, 159
       of results of Dr. Gruby's observations, 174

                                U.
Utility of the microscope in medicine, 19
Urinary  deposits, 143
Urea, 145
Uric acid, 143, 145, 159
                                V.
Vegetable physiology, microscope indispensable in, 14
Varley's dark chamber, 41
Vegetable tissues,  dissection of, 66
Vascular tissue in plants, 67
Vitality  and electricity not identical, 96
Valentin's knife, 106
Vital principle, theories respecting the, 96,114

                                W.
 Withering's Botanical Microscope, 33
 Wilson's Pocket Microscope, 24
 Wollaston's doublet, 30
            condenser, 41
 Watch-glasses useful, 48
 White fibrous tissue, 92
 Wheel animalculae, mode of obtaining, 172

                                 Y.
 Yellow fibrous tissue, 92
Zoophytes, 78
Z. 
M'AiLZiXSTEB.  &  CO.,
 No.  48  CHESTNUT  STREET,  PHILADELPHIA,

                Have for Sale a very large Assortment of

           COMPOUND  MICROSCOPES.

 Neatly mounted in Brass, of a power ranging from 15 to 60 dia-
   meters, from                                       $2 50 to $10
 An Achromatic Microscope, cylinder brass body, with rack-work
   and condenser—power 50 times.  Price,                  $16 00
 Ditto, with power 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-woi'k, 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 $050
 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;  Microscopes
to examine  the ear;  Urinometers, Thermometers,  Hydrometers,
Weighing Scales, Magnets, Mathematical Instruments,  Spy-Glasses;
Camera Lucidas, Stanhope Lenses, kc. 
 
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