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Modern microscopy; a handbook for beginners, in two parts online

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FIG. 1. A Topical Modern Microscope. Made by W. Watson and Sons
to the specification of Dr. Henri Van Heurck, Antwerp,
for Photo-Micrographic and High Power work.



MODERN MICROSCOPY.



A HANDBOOK FOR BEGINNERS,

IN TWO PARTS.



I. THE MICROSCOPE, AND INSTRUCTIONS FOR ITS USE,

BY

M. T. CROSS.






II. MICROSCOPIC OBJECTS: HOW PREPARED AND MOUNTED,



MARTIN -J. COLE,

LECTURER ON PRACTICAL MICROSCOPY, BIRKBECK INSTITUTION, LONDON ; LECTURER IN
HISTOLOGY AT MR. COOKE's SCHOOL OF ANATOMY.




LONDON :
BAILLIERE, TINDALL AND COX,

20 & 21. KING WILLIAM STREET, STRAND.

[PARIS AND MADRID.]

1893.

[All rights reserved.]



PREFACE.



THIS handbook is not intended as a treatise on the micro-
scope, nor to give particulars of the various patterns of
instruments made, details of which can be seen in the
makers' catalogues, but to afford such information and
advice as will assist the novice in choosing his microscope
and accessories, and direct him in his initial acquaintance
with the way to use it.

The directions for preparing microscopic objects by Mr.
Martin J. Cole are the outcome of a very long experience
as a preparer of Microscopic Object^ of the highest class,
and cannot fail to be of the greatest service to the working
microscopist.

M. I. CROSS.




CONTENTS.

PART I.

CHAPTER I.

THE MICEOSCOPE-STAND.

PAGE

On choosing a microscope -stand Designation of the parts of a
microscope Different forms of feet compared The stage Sub-
stage and underfitting Fine adjustment to sub-stage Coarse
and fine adjustments The limb Lengths and diameters of
body tubes The Eackwork draw-tube Tailpiece and mirrors
blique illumination Testing a microscope Binocular micro-
scopes High-power prisms Dissecting microscopes - - 16-37

CHAPTER II.

OPTICAL CONSTRUCTION.

Magnifying power, how produced Objectives, apochromatic and
achromatic compared Angular and numerical apertures Im-
mersion lenses Abbe apertometer Aperture and power
Corrections for thickness of cover-glass Test objects Huy-
ghenian eyepieces Kelner eyepieces Projection eyepieces
Binocular eyepieces Illuminating apparatus The Abbe illumi-
nator and Abbe achromatic condenser Webster condenser
Swift's condenser Powell and Lealand's apochromatic con-
denserHow to work with the condenser How to produce a
dark background Spot lens Paraboloid Polariscope
Darker's selenites - Mica selenite stage Stand condenser
Nelson's aplanatic bull's eye The microscope lamp Nose-
piece Drawing apparatus Dr. Beale's neutral tint reflector
The Abbe camera lucida The measurement of objects by
mechanical stage By camera lucida and stage micrometer



viii Contents.



TACK

Eyepiece micrometer and stage micrometer Jackson's micro-
meter Rarnsden screw micrometer Botterill's trough
Rousselet's live-cage Stage forceps Text-books recommended 38-68



P ART II.
LESSON 1.

HARDENING ANIMAL TISSUES FOR MICROSCOPICAL EXAMINATION.

Absolute alcohol Chromic acid and spirit Potassium bichromate
Ammonium bichromate Miiller's fluid Methylated spirit
Decalcifying fluid General directions for hardening - - 69-71

LESSON 2.

EMBEDDING TISSUES AND SECTION-CUTTING.

Cutting sections with a razor by hand Embedding in paraffin,
wax and lard Infiltrating a tissue with paraffin Cole's micro-
tome and embedding in carrot Cathcart microtome for freezing
Embedding in celloidin Cambridge rocking microtome - 72-77

LESSON 3.

STAINING ANIMAL SECTIONS AND MOUNTING IN CANADA BALSAM.

The preparations of borax carmine Logwood or haematoxylin
Staining processes Double staining with logwood and rosin
Mounting in Canada balsam - - 77-80

LESSON 4.

STAINING BLOOD AND EPITHELIUM, TEASING OUT TISSUES AND
MOUNTING IN AQUEOUS MEDIA.

Double staining nucleated blood corpuscles Preparing blood of
mammals Non-nucleated corpuscles Epithelium Teasing
out muscle, fibrous tissue, yellow elastic tissue, nerve fibres, and
non-striped muscle Farrant's medium and glycerine jelly,
how prepared and used -' 80-83

LESSON 5.

STAINING AND MOUNTING MICRO-ORGANISMS.

Staining and mounting micro-organisms Staining bacteria on
cover-glass Ehrlich's method of double -staining - 83-85



Contents. ix

LESSON 6.

INJECTION OF BLOODVESSELS.

PAUE

How to make carmine and gelatine injecting mass Prussian or
Berlin blue and gelatine mass Watery solution of Berlin blue
Directions for injecting Injection of lymphatics (puncture
method) Injection of lymph-sinuses of glands - 85-87

LESSON 7.

CUTTING, STAINING, AND MOUNTING VEGETABLE SECTIONS.

Bleaching Staining in borax carmine Haematoxylin Formula
for acid green and carmine stains and double-staining in same
Eosin stain - 87-90

LESSON 8.

PREPARING AND MOUNTING IN GLYCERINE JELLY, ACETATE OB-
COPPER, ETC.

Epidermal tissues ,for stornata Annular vessels Scalariform
vessels Spiral vessels Yeast Preserving fluid for green algae
and mounting in same Protococcus Volvox Bed algae
Antheridia and archegonia of mosses Fertile branch of
chara - - 90-93

LESSON 9.

CUTTING, GRINDING, AND MOUNTING SECTIONS OF HARD TISSUES.

Bones Kock sections - 93, 94

LESSON 10.

PREPARING AND MOUNTING ENTOMOLOGICAL SPECIMENS FOR THE
MICROSCOPE.

Preparation for mounting an insect with pressure in Canada
balsam Mounting without pressure in Canada balsam and
glycerine - 94-97

LESSON 11.

CRYSTALS AND POLARISCOPE OBJECTS.

Crystals, how prepared and mounted Starches Cuticles con-
taining raphides Fish scales Palates Hairs Horns, hoofs,
and whalebone - - - - - - - 97-99



xii The Illustrations.

*!<;. PAGE

25. R. and J. Beck's Ramsden Screw Micrometer - 66

26. Botterill's Trough 67

27. Rousselet's Live-cage - - 67

28. Cole's Microtome, by Watson and Sons 78

29. The Cathcart Freezing Microtome - - 74
80. The Cambridge Scientific Instruction Company's Rocking

Microtome - - - - - - 76



ERRATUM.

Page 30, line 10, for 'page 41 ' read 'page 4f>. '



MODERN MICROSCOPY.



INTEODUCTION.

THE history of the development of the microscope is exceed-
ingly interesting, and itself would fill a small volume :
suffice it to say that it was but sixty-eight years ago, or in
1824, that Tully made the first achromatic microscope.
Since that time, step by step, such progress has been
made in its construction as would be scarcely realizable
to those w r ho have not followed it. Ten years ago the
President of the American Society of Microscopists, in
his annual address, remarked ' that lenses which were
believed to have so nearly reached the limit of perfection
fifteen years ago are antiquated now r , and the theoretical
limit of perfection has moved forward like the horizon, and
is as far off as ever.' The same statement applies to-day,
and even within the last five years lenses have been placed
at our disposal by the leading opticians giving results that
our microscopical predecessors of fifteen or twenty years
ago would never have dreamed of ; and still further experi-
ments are going forward, with the view of giving greater
advantage in microscopical research. What has been done
in the lens part of the microscope has also been effected
in the mechanical, and a far better microscope can be
purchased to-day for a given sum than a few years ago
could be obtained at nearly double the cost, bringing that



14 Modern Microscopy.

which was a luxury, and acquirable only by the wealthy,
within the reach of the slenderest purse. This is largely
due to the work of enthusiastic amateurs. At leading
microscopical societies, notably the Eoyal Microscopical
Society and the Quekett Club, which meet in London, are
to be found men whose recreation is in the microscope,
and whose suggestions, as the result of personal practical
experience and research, are of such weight and value that
manufacturers, rivalling one another, have taken advantage
of the ideas of these workers. Also in the medical world its
advantages have become appreciated, and necessitated the
introduction of reliable and high-class instruments at a
moderate price. Not many years ago a hospital rarely
possessed more than one or two microscopes, and these
were generally kept under a glass shade, more for ornament
than use ; but to-day every student has to provide himself
with one, and become practically acquainted with the ulti-
mate structure of every organ and tissue both in health
and disease. The chemist finds it indispensable, and our
medical officers of health employ it for detecting adultera-
tions, entozoa, etc. ; so that not only is it one of the most
intelligent means of recreation, but it is also invaluable in
many duties affecting our immediate comfort and welfare.

The demand for microscopes caused by their large
employment by professional men and students caused a
corresponding competition among manufacturers to produce
the best possible instruments at the lowest price, suitable
for the purposes for which they were required, and this has
been an important factor in the present state of good
quality at low cost.

Some people hesitate in taking up the microscope at all,
not caring to use it merely as an amusement, and thinking
they have no special genius for science, or the ground has
been gone over so repeatedly that there are no new worlds
to conquer, and that it is perfectly hopeless for them to
discover any new organism, or for any novel idea to cross
their minds. This is quite a mistake, and it will surprise



Introduction. 15

any microscopist who uses his instrument thoughtfully how
the love for the work will grow upon him, and how gradu-
ally he will become master of some special line which he
has adopted as his own. On this point we would echo the
words of a well-known microscopist : ' It needs no mar-
vellous intellect, no special brilliancy, to succeed in a
scientific study ; work at it ardently and perseveringly, and
success will follow.'

We will now proceed to consider the microscope itself,
apart from its optical relations, which will follow in another
chapter.




PART I .



CHAPTEE I.
THE MICROSCOPE-STAND.

As one looks through the catalogues of the various dealers,
and notices the microscope- stands varying in price from 2
to 40, a bewilderment as to what is essential and what is
not is the first feeling. We will, then, examine the parts,
describe their uses and advantages, and state what is
essential to a beginner.

Here let us advise intending purchasers not to buy a
microscope unless it bears the name of a manufacturer : a
good workman is never ashamed of his handiwork. There
are many very inferior instruments that look tempting, but
a practical acquaintance with them soon discovers their
weak points and inefficiency. Happening to attend the
conversazione of a well-known microscopical society some
little time since, at which there were exhibited over one
hundred instruments, it was surprising to note the many
makeshifts of microscopes belonging to some of the exhi-
bitors and many of them had probably cost a fair price,
too. A manufacturer remarked to the writer that he was
some time since in a provincial town, when an auctioneer
asked him whether he could not make him up a job lot of
microscopes for sale by auction, as he was very successful
in disposing of a certain class of pictures in this way. The
disgust of the scientific workman can be better imagined
than described. The microscopes often seen in the novice's
possession seem to be of this genus. This kind of instru-




17



FIG. 2. Edinburgh Student's Microscope, Stand B, by Watson and

Sons.

ment is soon discarded, and little pride is felt in its posses-
sion after seeing a well-made one.



18 Modern Microscopy.

Although good second-hand instruments may be occasion-
ally met with, great discretion is required in purchasing,
owing to the improvements that have been introduced in
the first place, and that some damage may have occurred to
the optical parts in the second place. If it be obtained from
a respectable dealer who understands his business and will
give a guarantee of condition, there is some inducement ;
but a friend who is up to date in microscopy is generally
the best to advise. In all cases, before purchasing, a cata-
logue should be obtained from the maker whose name the
instrument bears, so that it may be ascertained whether the
pattern is still made or is antiquated and out of date. It is
much better to buy a good stand capable and worthy of
receiving additional apparatus from time to time, rather
than a complete cheap instrument. These latter rarely
engender pride of ownership, and are often relegated to
some obscure corner after a short acquaintance ; whereas if
a good instrument be purchased, with even only one objec-
tive to start with, there is always a pleasure in working with
it, and a peculiar fascination from its quality a satisfaction
in feeling that one has something superior.

There are several very cheap microscopes on the market,
and although it is sometimes claimed that they foster the
scientific spirit and educate the microscopical beginner, it is
very doubtful whether they do not do more harm than good
from dissatisfaction with their performance on comparison
with those of superior make : possessors of such become dis-
heartened, often attributing want of success to themselves,
and not to the instrument.

To make the different parts quite clear, on page 17 is
figured a student's microscope, of which the following is a
description :

FIG. 2. A is the stand or foot.

B is the tailpiece carrying the mirror (C) with which light
is thrown upon the object.

D is the under-fitting, into which are fitted the sub-stage
condenser, polarizer, etc.



The Microscope-stand. 19

E is the stage on which the ohject is placed.

F is the limb carrying the body (G).

At the lower end of the body is a screw, into which the
objective (H) is fitted.

At the upper end of the body is a sliding fitting called the
draw-tube (J), by means of which additional magnification
may be obtained, and into this draw-tube the eyepiece or
ocular (K) fits.

L is a rackw r ork, by means of which the body (G) is raised
and lowered in order to focus the objective (H) upon the
object which is placed on the stage (E).

M is the milled head controlling the fine adjustment,
which imparts a delicate motion to the body, in order that
the objective may be more exactly adjusted than would
be possible with high magnifying power with the rack-
work (L).

N is a fitting for forceps, or side silver reflector ; and
are the springs with which the object is held in position.

We have selected the instrument (Fig. 2) as, from prac-
tical acquaintance with it, we are able to strongly recommend
it for a beginner's microscope, worthy of receiving additions
from time to time as means may permit, especially as it
may be had on a tripod form of foot similar to that shown
in Fig. 1, instead of the horseshoe form. Still, it should be
only considered as a typical one.

THE FOOT.

We would very strongly advise the beginner to purchase
an instrument with a tripod foot, as shown in the instru-
ment Fig. 1 (frontispiece). This is the most rigid form of
foot in the market, and is in this respect a long way in
advance of the horseshoe stand with a single pillar, so
largely adopted on the Continent.

If the horseshoe foot be made in proper proportion, it is
not so condemnable ; but unfortunately it rarely is, and at
the best is not nearly so firm as the true tripod foot recom-
mended. This is a most important feature; and though



20 Modern Microscopy.

perhaps inappreciable to the novice, yet as he advances all
these minor details come up as very real ghosts, haunting
him in his work and causing him to avoid that which would
have been useful to him. If the foot of the microscope be
shod with cork, so much the better, as vibration is thereby
partly insulated,, and the annoyance caused by scratching
tables is avoided. It must be clearly understood, however,
that even if this form of foot be not made in proper propor-
tion its advantages will be annulled.

Next to this foot in point of convenience and rigidity we
would place the Jackson model, as shown to the instrument
on page 29. This, if properly made, is but little inferior to
the tripod, but it is heavier.

There are many others made, mostly modifications of the
Jackson model, and then* rigidity can be tested by placing
the instrument in a horizontal position, racking the body
out, and then observing whether there is any tendency to
topple over. If so, have nothing to do with it. The double-
pillar form, with flat tripod foot, as shown on page 34, is a
very good and convenient one. It is adopted by several
firms for largest size instruments, and is certainly hand-
some.

Last on our list of feet we should place the horseshoe
pattern, as shown on page 17. The great advantage this
possesses over all others is its compactness for portability.
It originated on the Continent, and is preferred both there
and in English medical schools, etc., before any other.
It is usual in laboratories to work with the microscope
in a vertical position, and while the instrument is so
placed the horseshoe foot is quite firm. If it be placed
horizontally, however, as the amateur usually employs it,
even with a well-made foot there is a tendency to side-
falling. It would be well, therefore, not to select this form
of foot when choosing a microscope. The order of prefer-
ence for the foot of the microscope would be :

1. The tripod foot, as shown to instruments page 81 and
frontispiece.



The Stage., 21

2. The Jackson form of foot, as shown to instrument
on page 29.

3. The flat tripod and upright pillars, as shown to instru-
ment on page 34.

4. The Continental or horseshoe form.



THE STAGE.

It will be noted, on reference to the typical instruments
shown in this book, that the stage of the instrument on
page 17, on which the object is placed, is perfectly plain,
while those on pages 29, 31, etc., have screws, by means of
which plates move in dovetailed grooves one over the other
in rectangular directions, carrying the object with them.
In a first-class microscope it is well to choose ah instru-
ment having this convenience in fact, there is no means
so suitable for systematically examining an object as is
afforded by it. In addition to these mechanical movements,
if a sliding bar be fitted to slide on the top plate the con-
venience is greater. For plain stages beyond the springs
nothing is really necessary, and it is surprising how with a
little education the fingers will do the work of the mechanical
screws, so that the object may be carefully examined under
high powers. A sliding movement or some form of carrier
on a plain stage is preferred by some.

A very great convenience to the mechanical stage is the
rotation, and this in a best instrument should be con-
centric ; some stages are fitted to rotate by rackwork, but
this is rarely necessary : it is often found convenient for
preventing the stage from rotating accidentally, especially in
photography, and should always have the pinion wheel so
fitted that it may be disengaged from the rack and replaced
instantly. Centring screws to the concentric rotating
stage, by means of which the rotation of the stage may be
made true with any objective, will be found a useful
addition. Divisions to the rotation of stages are not very
advantageous for ordinary purposes, but for geological work

2



22 Modern Microscopy.

are a necessity. A scale, reading to parts of a millimetre or
inch on the plates of the mechanical stage, will be found
useful, as important parts of an object can be noted and
refound. For instance, supposing a specimen were being
examined, and any important feature observed to which
future reference would be convenient, the reading of the
divisions on the stage would be marked on the slide say,
horizontal, 24 ; vertical, 20. On future occasions it would
only be necesteary to set the stage readings at the same
points and place the object in the same position on the
stage (for which purpose nearly all mechanical stages have
a stop-pin for the slide to be set against), and the special
feature will be in the field of view. If a mechanical stage
be selected, it should be a good one, as if badly made it is
worse than a plain stage ; also the frictional parts should
be fitted with adjusting screws to compensate for wear and
tear.

For a stage for a microscope we would therefore place
our choice as follows :

For a first-class microscope : Mechanical movements ;
concentric rotation ; screws to make the rotation quite true
with any objective; sliding-bar to top plate and stop-pin for
object to go against ; divisions to plates of stage reading
to parts of millimetre or inch ; rackwork rotation to stage ;
and divisions to outer circle (optional).

For a second-class microscope : Mechanical movements ;
sliding-bar to top plate.

For a third-class microscope : Plain stage, with springs
to hold object in position ; if provided with sliding-bar or
plate as object-carrier, so much the better.

THE SUB-STAGE OR FITTING UNDER THE
STAGE TO CARRY CONDENSER, ETC.

The sub-stage consists of a ring of what is termed the
' society size,' 1J inches full internal diameter, which
carries illuminating apparatus for condensing the light on



The Sub-Stage. 28

the objects, polarizing prism, etc., referred to on a later
page. It is adjusted in a vertical direction towards the
under surface of the stage by means of a rack and pinion,
and the ring carrying the apparatus is provided with screws,
by means of which the condenser, etc., can be made exactly
central with the objective with which it is working. This
central fitting is made to rotate by rack and pinion in some
instances for using the polarizer, etc., but this is so rarely
needed that it is hardly necessary except for special work.
It is essential that this should be substantially made, as it
is a most important fitting, often too little appreciated.
For the sake of economy, some makers fit a sub-stage with-
out a rackwork, merely sliding up and down in the dove-
tailed fitting ; this is not desirable. If a sub-stage be had,
it should have a rackwork, or nearly all its value is lost.
A fine adjustment, so that the most exact focus can be
obtained with the condenser, is often provided with the best
stands, and is very useful if high-power work is intended to
be done. It is surprising the convenience this fine adjust-
ment affords. Often it is wished to just altei the position
of the light and sub-stage condenser a little. In so doing
the tension on the sub-stage milled head is apt to cause
vibration, so that thle best point of adjustment cannot be at
once observed. By communicating this small amount of
motion with the fine adjustment the focus is obtained to a
nicety.

In the cheaper instruments, instead of the sub-stage as
above described, an ordinary plain tube is fitted into the
under part of the stage, and in this tube the condenser or
other apparatus is moved up and down to focus. This
must be truly centred with the optical tube, and it is well
to test it by putting a small diaphragm into the under tube,
and with an objective in the body to focus the diaphragm.
If it be not central its practical importance is annulled.
The additional convenience of the centring sub-stage is well
worth the extra outlay. The instrument in Fig. 1 has a
rackwork ; Fig. 2 has a plain tube only.



24



Modern Microscopy.



A great convenience will be found in many instruments
of being able to lift the sub- stage aside out of the optical
axis of the instrument on a jointed fitting. It saves a deal
of time to students, especially where two or three powers




F IG . 3._View of diagonal Kackwork attached to one of Watson and
Sons' Microscopes, showing Dovetailed Fittings to receive Fine
Adjustment Slide and Adjusting Screws (marked A).

are constantly being changed, and the condenser may not
be required for all of them. Where this arrangement



Arrangements for focussing. 25

exists, it should be fitted in a workmanlike manner, and a
proper support given to the fitting when in the optical axis
to make it perfectly rigid.

The choice with regard to a sub-stage would therefore be

In a first-class microscope : Hackwork and centring
adjustment and fine adjustment ; rackwork rotation, if for
examination of crystals or petrology.

Second-class instrument : Eackwork and centring adjust-
ments, and means of lifting aside out of the optical axis.

, Student's instrument : The same as the second-class or
the plain tube fitting.

ARRANGEMENTS FOR FOCUSSING.


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