The preparation & mounting of microscopic objects

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1 ^^„%rvA^.^^/i^:y^^,

TBB

PREPARATION AND MOUNTING

OF

MICEOSCOPIC OBJECTS.

<5^

THE

PREPAEATION & MOUNTING

OF

^MICEOSCOPIC OBJECTS.

Br
THOMAS DAVIES.

Sittmd (K)nim.—§xtutlia (ffniarjtb*

Edited by JOHN MATTHEWS, M.D., F.R.M.S.
Vice-Fre». Q^€^ett Microse<^ic(d Club.

NEW YORK:

G. P. PUTNAM'S SONS,

FOURTH AVENUE AND TWENTY-THIRD STREET.

1874.

'the N£w

[PUBLIC

VORK

UBKARY

163209

ASTOR
TILDEN

. LENOX AND
FOUNDATIONS.

1899.

* •

" •• •• ...

PREFACE TO THE SECOND EDITION.

rPHE reception accorded to this work has been so
favourable as to indnco tlie Publisher to issue
a second edittonj in which such new matter ebould
be embodied as the progress of Microscopic science
might require. He therefore applied to the Author,
but he found to hig regret that the state of Mr.
Daviea's health was such aa to forbid his under-
taking the labour. He had, however, collected
many valuable notes and memoranda, which he
was willing to place at the disposal of any gentle-
man who might be selected to edit the work. The
Publisher then consulted the present Editor, who,
after some hesitation, consented not only to use
his best efforts with the ample materials placed at

Tl PEEFACE TO THE SECOND EDITION.

his disposal^ but also to make such additions as his
experience might suggest in extension of the use-
fulness of the book to a new class of readers, — the
Medical Student, and the Junior Medical Practi-
tioner. To this end, besides other matter, a brief
prefatory chapter has been added, embracing the
elements of preliminary histological manipulation.
While claiming the indulgence of the elders of his
profession, — ^the Editor feels that the best and truest
apology for this treatise, its raison d^etre — ^in fact,
may be found in the words of its concluding para-
graph, to which the reader is now courteously
referred.

4, Mtlne I^teeet, Mtddelton Squabe, E.G.
October, 1873.

PREFACE TO THE FIRST EDITION.

TN bringing this Handbook before the public, the
Author believes that he is supplying a want which
has been long felt. Much information concerning
the '^ Preparation and Mounting of Microscopic
Objects ^' has been already published ; but mostly
as supplementary chapters only, in books written
professedly upon the Microscope. From this it is
evident that it was necessary to consult a number
of works in order to obtain anything like a com-
plete knowledge of the subject. These pages,
however, will be found to comprise most of the
approved methods of mounting, together with
the results of the Author^ s experience, and that
of many of his friends, in every department of

Tiii PREFACE.

microscopic manipulation; and as it is intended
to assist the beginner as well as the advanced
student, the very rudiments of the art have not
been omitted.

As there is a diversity of opinion as to the best
mode of proceeding in certain cases, numerous
quotations have been made. Wherever this has
been done, the Author believes that he has acknow-
ledged the source from which he has taken the
information; and he here tenders his sincere
thanks to those friends who have so freely allowed
him to make use of their works. Should, however,
any one find his own process in these pages
unacknowledged, the Author can only plead over-
sight, and his regret that such should have been
the case.

Warrington

THE

PREPARATION AND MOUNTING

OP

MICROSCOPIC OBJECTS.

CHAPTEE I.

INTRODUCTION.

Tms work having been written chiefly to help studentp,
the writer does not venture to affirm of it that it is bj any
means complete or exhaastive. The art of microscopic
manipulation is progressive, and it is scarcely possible,
therefore, to say of a work on the subject, that it holds all
that is known at any given time. It is an art, too, which
is BO inextricably mixed up with the highest branches ri
scientific inquiry, that new modes of investigation are daily
devised by the acntest intellects, and with these it is very
difficult for a writer to keep pace.

It is a well-nigh hopeless task to attempt to teach encli
modes of inquiry by precept, yet it is felt that some short
account of them may reasonably be expected here. Befci r
ence is now made more particularly to the practical part of
human and comparative histology. As this is not a treatise
on histology, but is devoted mainly to the methods of pre-
serving the results of researches in that science, it is scarcely
possible to indicate to the student how he shall proceed in
any given case ; yet there are certain tests, reagents, ani
staining matters employed, with the uses and effects of

B

2 FBEPARATION AND MOUNTING

whicli be slionld be familiar, so as to be able to speak with
some degree of certainty of the natare of the tissues demon*
strated by them.

It is now, therefore, intended to give the reader a list of
these aids, arranging them according to the effects which it
is desired to produce. Strieker observes, ** that it is to be
borne in mind that it is impossible to say of any fiaid that
it constitutes an indifferent, i,e., neutral, medium for fresh
tissues of all kinds. In all instances we must be prepared
for changes taking place." He gives, however, a list of
fluids to which structures are generally most indifferent, i.e.,
in which least alteration may be detected under examina-
tion while fresh, viz. : —

1st. Fluid of the aqueous humour.

2nd. The senim of the blood.

3rd. Amniotic fluid, very fresh, in which a little iodine
has been dissolved, making it of a faint yellow tint.

4th. Very dilute solutions of neutral salts, such as phos-
phate and acetate of soda and potash, &c.

It is scarcely within the power of any one -observer to
have largely used or tested the whole of the processes here-
inafter to be mentioned. The writer therefore freely admits
his obligations to the treatises of Drs. Beale and Carpenter,
Mr. Qnekett and Mr. Fownes, as well as to those of Strieker,
Frey, Klein, Schultze, Kiihne, Deiters, Leber, and others,
many of whose processes he has personally verified, and of
whose manuals, especially those of Beale, Strieker, and Frey,
the student is advised to possess himself. He believes also,
from his own early experiences, that some short rationale
of the intentions of the processes and means of investigation
used by well-known workers may be acceptable to the stu-
dent, in repeating their experiments before embarking in
any of his own.

These materials and methods may be divided, then, and
described according to their effects somewhat as follows ;
and it is in the judicious selection of each one or more of
them that the tact and discretion of the student will best

ECTs. a

1m bIiowh. Ke slionld boar !□ luind, too, that tho same
Btrncture may well be snbmilted to sarious modes of in-
qniry. and tbut poasiblj new iDodt^s maj occar to bim wbich,
thonj;h they may not aerre to prove anything directly, may
jet beoome negative proofs.

lit. Bach tests and agents as render transparent oi
translucent some tissueB but not others adjacent, or malia
(Ome mare eonspieuous than othera without colouring them,
ir at least hat faintly.

Sod. Staining materials or flnide, which colour either all
the tisanes to ba displayed, or some particular part nr pirta
of them, thns making such tiiisaea or parts more conspicuous
when anbaequently eiamined or preserved in a colaurlese

3rd. Hardening egcnts or aolationa, by the effect of
trbich tiesuea naturally ao soft aa to break down or be other-
tnageable under maoipnlation, are made firm
enough for aectioo, or for BQoh eiaraination as may suffice to
to discriminate (Or "differentiate") their parte, without
either diatnrhing or confusing thtir structnral relations.
4th. Softening agents of animal and vegetable tissues.
Bth. SotvuntB of the same.
6th. Solvents of ealcareous matter.
7th. Solvents of silioeona matter.
8th. Solvents of oily and fatty matters.
fltb. Polarized light, by the agency of which atrncturea
and organs may often be optically differentiated as a pre-
UminBry to other modes of investigation,
10th. Eltctricity and heat.
11th. The moist chamber.

In dealing with stracinres by means of the agenta com-
prised under the firet division of oar list, a very frequent
■nd necesBBi'y preliminary is the teasing out or separation
f fibres by means of two abarp needles set in convenient
AiidleB. Bat it must he rememliori^d that an appearance
of Btractore, where it does not really enist, may easily be
B produced. It is often necessary, also, that the object
b2

4 PKEFARATION AND IIOUNTIHG

shall have been macerated in water, or some other agent,
for 80 long a time as may be required to loosen or dissolve
the connective tissue. Tt is of these agents that we shall
presently have to speak in detail, greater or less according
to their relative importance. Boiling or steaming may
often be employed with advantage. It mnst not be too
hastily concluded that, because there is nothing at first
visible, there is therefore nothing to be seen. There are
many important tissues which are apparently structureless,
or homogeneous, which yet are possessed of such diverse
elements as absolutely to require some process by which
they may be optically or visually differentiated, if one may
nse such a phrase, i.e., discriminated from the neighbouring
tissues or organs. It is thus that their proper uses and
purposes in relation to the whole organism may be correctly
indicated or inferred, their histological nature decided, and
their physiological relations and connections established be-
yond doubt.

The student is also very emphatically cautioned against
the use of objectives of very wide angle, as well as of
deep eye-pieces. In the former case, the relations of
structures to each other can never be well made out, since
it is impossible to get a focus of any depth (i.e., of all the
structures involved), in one view, because the objects in one
plane only can be clearly seen, the rest, either above or below,
being more or less out of focus, and therefore hazy and
indistinct. This objection applies far less to those of lesser
angle, which are therefore the beat for histological purposes.
In the latter case, we have nearly the same defect to con-
tend with, viz., that surface markings only, or mostly, can
be seen clearly (not to speak of the loss of light). The use
of the draw-tube is the true remedy for this.

OF MICEOSCOPIC OBJECTS. 5

lar DiviMoN,
TToder i^nr first tea.! may be raageiJ the following ; —
Acetic acid.
Iiiquor potaat^Ee and sodro.

icentrateii sulphuric and hjdroclilorio acids {the latter
saturated nit^ dilorine).
Tansia.

Lime and barjta water.
Oxalic acid.

Nitric acid witli cblorate of potasb.
Ammonia.
Aleohol.
Iodine.
Gljcerine (?)
Pbospborio acid (tribaflic).

Acetic acid mora or lesa dilate, e.g. one part to fi^e of
water, after a aofScieotlj prolonged immersion, reoderB
iran^arent tbfl following tiesnes, without in geDeral des-
trojiing their connective tissue: — some tnusdes (of the frog
(EKlliber),) cell-walls generally (ont the oucleas), epithelial
fltmotaree, while Bbroua tissue. Dr. Beaie sajs that yellow
flbrouH tisane is uuallered hy it. Many kinds of formed
tnalerial, acctiona of preparations which have been hardened
by alcohol. Dr. Beale also aaya that it dissolvea granular
matter compoi^ed of albuminous material, and that many
tiuDea are quite insoluble in it, though they are not ren-
dered opaque by it. Acetic acid renders some tissuea trans-
parent by dissolving out the phosphate or CEirbonate of lime,
vhioh they may oontaiD, but it bas no similar snkent power
over oxalate of lime. Farts which are unaffected by this
arad are then made more conapicuous.

Liquor polas^is and liquor sodte act in much the same
way, according to the degree of their dilution, but on different
Btrnctnrea. Albumiuona tissuea, cpitbulinm, &c., are either
dlBiotved by them or rendered ao traneparent aa not to
, obslmct the view of the aubjacent stmctaves,

6 PREPARATION AND MOUNTING

Concentrated snlpburic and lijdrocliloric acids, used cold,
cause epidermic stractares to swell up, so that their cells
may be easily separated.

Tannin, dissolved in water or rectified spirit of wine,
hardens gelatinous and albuminoid tissues : it also makes
them shrink. Its solution in water has been used, as men-
tioned in another part of this treatise, as an injection pre-
liminary to one of coloured gelatine, to prevent extravasation
through the walls of the blood-vessels. It also colours the
tissues a fawn-colour, or a very faint brown.

Lime water and baryta water, especially the latter, will,
according to Kullet, dissolve the animal cement by which the
fibres of connective tissue are held together. After a few
days' soaking such tissue, as well as tendon, may easily be
teased out by needles.

Oxalic acid, in a cold saturated solution (I acid, 15
water), according to Schultze, " causes connective tissues to
swell up and become transparent, while those formed of al-
buminous substances become hardened and isolated. Ex-
tremely delicate elements of the body, such as the rods of
the retina, &c., are thus well preserved."

Strong nitric acid mixed with chlorate of potash destroys
connective tissue in a short time, and is therefore a good
.medium for isolating muscular fibres (Kiihne).

Sulphuric acid, highly diluted (1 to 1,000 parts of water),
used warm, gelatinizes connective tissue, and is also useful
for the isolation of muscular fibres.

Strong hydrochloric acid dissolves the intercellular sub-
stances of organs abounding in connective tissue.

Ammonia acts on animal matters much in the same way
as potash and soda.

Alcohol coagulates albuminous tissues, and makes them
opaque. It corrugates most transparent membranes, and
thus renders them more visible.

Finally, it may be affirmed that there often exists a need
of making objects which are too dark more transparent by
means of a fluid which permeates them uruqually, bo thsit

OF Micftoscopic oBJKcrs. 7

10 tiBsaea are ttereby aa it were " differentiated," jet nob
altered in any material degree. This maj be effected by
so1utioD8 of gun), pugar, glycerine, aod crensute, if the
tisBueB are moist. If dry, then turpentine, Canada balsam,
benzine or benzole, and the essential oils of clovee, aniee,
and caBHia, may be employed.

2nd DiYisioB.

tJnder the secaDd divieioa of our subject oome ataining
floida.

Many of theae wilt be found mentioned in the body of this
worlc. They comprise carmine Bolutione, botli acid and
alkaline; aniline coloora, indigo, carmine, baimatox^linc,
&c, formnltB for the nee of which are given. To these Prey
adds, bine tingeing by moljbdate of ammonia, and doublo
staining by carmine and picric acid.

A neutral solntion of the molybdate of ammonia of the
atrength of 5 per cent, gisea a bloe tint to nBrTe-tisBna.
lymphatic glands, and ciliated rpitht'lial cdls, after macera-
tion for 24 hours iu the light.

For double staining by carmine and piorio acid he recom-
mends a mixture containing —

1 part creosote,
10 parte acetic a<
20 parts water.

;ld.

Soak the tiesnes in this eolation while boiling for about a.
minute, then dry for two days. Wake thin sectioDS of them,
imiaerse fur an hour in irater fuiutly acidulated with
acetic acid, and then waah in distilled water, Next place
tbem in a very dilute watery Hiilution of ammoniacal car-
mine, waeb again iu water, and place in a sulutioa tif picrio
acid in water, the strength of which will vary according to
circnmHtancuii. The sectiona are then to be placed on a
dlide, super&uoDB acid allowed to drain off, and a mixture ol
4 parta creosote to 1 of old resinous torpcntine dropped on

8 PREPARATION AND MOUNTING

them. In about half an hoar thej will become transparent,
and may be monnted in Canada balsam.

*' A peculiar effect is thus obtained. Epithelial and
glandalar cells, muscles, and the walls of vessels show a
yellowish colour, with reddened nuclei, while the connective
tissue is not coloured by the picric acid, and only presents
the carmine colour."

Another mode of effecting the above is by adding to a
saturated and filtered solution of picric acid in water, a
strong ammoniacal solution of carmine, drop by drop, nntil
neutralization takes place. Sections may be soaked in this
solution, more or less dilute, for a sufficient time, and
treated as in the previous method.

The other staining agents are : — nitrate of silver, osmic
acid, chloride of gold, chloride of gold and potassium, proto-
chloride of palladium. These are to be made into weak
solutions in distilled water, in which the tissues, in section
or otherwise, are to be placed, and then exposed to light for
a sufficient time.

L'ber recommends a mode of staining by Prussian blue,
as follows : — Immerse the specimen in a weak solution
of a protosalt of iron for five minutes, more or less,
according to size or the thinness of the section. Then
wash and move it to and fro for a few minutes in a
1 per cent, solution of ferro-cyanide of potassium until it
assumes an intense and uniform blue colour. Then wash
in water, soak in alcohol, and mount as usual. The effect
is that of partial tingeing ; the colour penetrates very
deeply, and the tissue may be subsequently stained with
iodino, carmine, or fuchsine. This method has been used for
the cornea of the frog.

Iodine 1 part, with 3 of iodide of potassium, dissolved in
600 of water, may be used for tingeing of a brown colour
animal cells, as well as all amjloid substances, animal or
vegetable, sulphuric acid being added.

OF mCILOSCOPIC OBJECTS. 9

3aD Division.

Under the third diviBiOD of oar list maj be ranged the
followiog agenta : — alcobol, solotioDS of chromic acid, bi-
chromate of potaah, hjperosmic acid, chloride of palladium,
bichloride of raercnry (in Goadbj's aolulion). and tannin, or
the Bubstaoce may be dried in thin layers or small pieccB,
either epoDtaneoDsly or in vacao, or by oarerully regolated
heat ; in sDDie Cases it may be boiled, or it may be frozen.

Alcohol is, on the whole, the beat and raoat cooceuient of
the hardening agents. It acts by abatraoling water and
coagolating atbumcn, and its nses aa a presorrative fluid
per se are well known. It enters also into many of the
preserTative fluids, and ia eapecially convenient and useful
when it ia deaired to mount apecimens quickly out of watery
flaids in Canada balsain, without drying them previonaly.
After a longer or shorter soaking in it, according to their
aiie or thioneas, preparations may be at once placed in tnr-
pentine, and then easily and speedily pot op for eiaraina-
tion in balsam.

Dr, Beale recommenda a mixture of alcohol and a soln-
tlon of caustic soda for the preserTation of delicate tiasnes.
He observes, " that alcohol alone tends to coagulate albn-
minouB textures and rendor them opaque, at the same time
that it hardens them. The alkali, on the other hand, will
render them soft and transparent, and wonid dissolve them
if time were allowed. These two fluids, in conjunction,
harden the texture, and at the same time make it clear and
transparent."

Chromic acid in solntion, 025 — 0-5 to 1 and 2 per cent.
of distilled water ia much used. On acconot of its deli-
qnescence, it is most convenieotly kept in a saturated sola-
tion, which may be dilated as desired ; and very often the
weaker this aolutioo the better. When it baa had the de-
sired effect on the tissue, the preparation should be removed
iota dilated alcohol, on accooat of the readineGs with which
fangi and confeivoid growths are formed in chromic acid

10 PREPARATION AND MOUNTING

BolatioDS. There are some precautions needed for perfect
saccess with this agent, for which the reader is referred to
Frey's " Microscopic Technology."

Bichromate of potash, in solutions of similar strength to
those of chromic acid, may be used in the same way, but is
far slower in producing its effect, and therefore inferior in
the opinion of many. Strieker, however, says, '* that it has
the great advantage that tissues saturated with it do not
become friable, and that the time occupied by this agent,
as well as by the preceding, may be much shortened by re-
moving the preparation into alcohol for twenty-four hours."

It is always advisable to divide the substances to be har-
dened into portions as small as convenient, since the larger
often putrefy in the centre, though they harden at the sur-
face. It is quite certain that many of the more delicate
structures, such as the rods of the cochlea of the ear
(Pritchard), those of the eyes of insects, &c., are better
prepared with this than by the preceding agent. One great
element of success in these two processes is, that the volume
of the solution should be very large in proportion to the
size of the object; another, that the action should be
commenced with a weak solution, and continued with a
stronger.

It sometimes happens that objects may be hardened too
much by these solutions, though there is less risk by the
bichromate of potash. In such cases Frey recommends that
they be soaked in glycerine for a few days, and even that it
be added to the solutions at first. He, with Deiters, Arnold,
Scholtze, and Kiihne, claims for these solutions an effect of
the most important kind, viz., that of " preserving the finest
textural relations, while exerting a somewhat macerating
action on them, so that very delicate organizations, especially
in nerve tissues, may be made visible which were previously
hidden, or not visible in examination of the fresh tissue."

Hjperosmic acid and chloride of palladium are sometimes
used for this purpose also. Their solutions may contain
from one-fifth to one-tenth per cent, of distilled water.

or MicEtttfonc objects. 11

Bichloride of meTenrj acts, in hardeoiiig tis.*u«a (like
most of the preceding, probablj), ty conibiciiig and forming
ftn inaoluble compound with their albuminoid elements. It
is Dot mnch employed for this purpoee, bnt is principallj
of use in certain preaervatiTe Bolalioiis mentioned elsvwhero
in these pages.

Tannic acid forma inaolnble componnda trith a great
Tariety of organic and especially animal substanceB, as bii1u<
tions of starch and gelatine, solid maacular fibre and skin,
&c., which then acquire the power of resisting putrcfdo-
tion. It Bcaroely oolonra animal membrane. Dr. Benle
Bays that its action upon red blood corpasclea is " Tt'rj
pecnliar." The Eolation need is three grains to an oanoe of
water. Other nsea of tannin (tannic acid) will be found
elsewhere in this work, and the intelligent student wilt easily
tbence infer its action and properties.

Drying may be effected either in a current of warm dry
air, or under a bell-glasa oier sulphuric acid, or over a lajfer
of parched oatmeal ; or a cheap form of water hath may be
employed, auch as will be found described in thia work.
Another very speedy method is to soak tfae speuimen in
strong alcohol for a sufficient time, remove it, and expose to
a corrent of warm dry air.

Boiling. — Tiasnea may he hardened by boiling in a. fluid
conaiating of 8 parts water, 1 part creosote, and 1 part
Tinegar, for two or three minutes. They may then be kid
out to dry. After two or three days they acquire a firm-
nesa admirably adapted for section ; bat if they remain too
long uncut they become of a consistence unfit for that pnr>
pose. On the whole, boiling is not to be recommeDded,
though Strieker says that it baa ita occasional uacs.

Freezing may be employed for otherwise unmanageable
etrnctures, auch as brajn, spinal cord, &a. (though there
BeeniB to be an oltjuction of a theoretical kind to this use of
it, Tiz., that it may iojare or alter the cells), or other tfssuea
wliich will notadmit the u»e of chromic acid, or which it may
be desired to view usder other aspects.

13 FKErABATIOS ASn UOCKtDi<3

Tbe writer has little or oo ei[>erieiiee of this pIoD, he
therefore qnotea from Frey as folIowB : —

'■ Tne preparation ia allowed to freeee (by contact, it ia
preBomed, with a freezing miitare or solution) nntil it as-
■umeB a oonBistencj which will permit fina lectionB to bs
inaJe with a cooled razor. The ol^ect is more coDreuietit to
handle if it ia allowed to freete on a piece of uorV. Nerrea
and mDBclea have been treated in this manner with good
results. Glands (aalivarj), livers, spleeaB, the Innga, sMa,
and the bodiea oF embryoii (see Beoile's process for the b:
in this work), also ganglia, afibrd excellent appearances.
Indifierent (or neutral) media, each as iodine serum, s
be used in examining auch sections. Or the preparation may
be held in paraffins wax (dilated or not with oil), or talloWi
which have been melted, and the ohject saapended or
plunged in them until they cool, and tbe cooling may be
carried fiirtlier, if nocdcd, by freezing."

In reference to this subject, Mr. Kesteven informi
author tbet he has foand tbe paiaffine composition mora
nstful for brain than spinal cord. Tbe former can be oat
into any angnlar shape, and be so held steady for slicing;
but the cord, being round, becomes loosened in its setting of
wax (or paraffine), and resolves with the pressure of the knife,
For either brain or cord he prefers hand-cutting with a vary
sharp razor, after the manner of Lockhart Clarke (see Mr.
K>-Bteven'B paper in 6t. Bartholomew's Hospital Beports).
If many eeotions are to be made from a brain, machine-
cutting saves much time. The razor should have t
spirit of wine dropped on it, bo ae to prevent the 8eotLon»
adhering. The cutting machines are generally graduated
(by a screw and index) on the upward movement, so as to
enable one to judge of the thickness of the section ; bnt aa
the brain substance and paraSne are both yielding to a cer-
tain extent, the reading mnst be taken with allowance.

07 KiCKosconc oBJict*. 13

4t[i DivisiOH.

lUa inclades gljcerins, liqnor potoMffi and «odit>, hfni (u
regards »ome Babstances), maceTntiou (carried lii inoipient
pntrescence), nitrio and oblor-hjdrio aaids, elllior pura ur
dilate (ia the cose of bones, nails, &<:.).

The writer is in donbt whether glycerine onglit nr not to
be indnded under this aection or the first, ill u*pii niid
effects being ao varioaa and interealing. ladrcd, tbprii it
Bcarcel; an; agent tn which hiiitologjr in mora iudvbtnd for
its present status and progress, since there is now no donbt
that elementary tisane can he more readily didwiiniufttnd lo
this medium — perhaps, too, hij it — -than any otlier. Tt has
also the valonble property of preseniug tho tiKsuen, if it he
not too much diluted, and even then it is geoprally eHoutiiat
if camphor water be employed as the diluent. Tho ntrongest
and beat glycerine should always be employed, The flrit
effect on tisanes immersed in it is that they shrink, owinj}
to the abatraction of their water; bnt Dr. ISi'ulo upeiiUs in
the highest terms of its nnes and advuntagcn, nnd declare*
that the tissues gradually regain their original Tolunio it'
left in it for a sufSuient time. They then soften, and eTeti
swell up. nia practice is first to immerse the Npcciinen in
tueak glycerine solntion, and then gradually to Incrciinc the
density of the fluid. Ho recommends, also, " in ordi^r thul
tiasnes may be oniformly permeated nith a HuJd wilhiri n
very short time after the death of an animal, tliab thn llniil
shonld come quirkly in contact with every part of the texture.'*
This, he saf a, may be effected in two ways, by

a. Soaking very thin pieces in the fluid;

S. By injecting the tloid into the f esselfi of the animftl.

He thinks that these properties more particulnrlj np]ier-
tftio to glycerine than to any other medium, and afSrnil
tliat"cerebral tissues, delicate nervoon tisinea liho tho retin*
or the nerTe-teitarcs of tbs internal car, may he aatarkl«4
with it,anii dii»ection then earruxl la a degree of v '

14 PESriRAIlOK ASD SIOUNTING

impas^ihh -in any other inediiim. All that ii required is,
that the streogth of the fluid should bo increased very
gradaally natil the whole tisane is thoronghly penetrated bj
the stroDgest that caa be obtained;" and " that thus very
hard iexluree may be softened, eo that b; gradaally increas-
ing preseore and careful manipulation esceediogly thia
layers can be obtained, without the relation of the anatomic
cal elements to each other beiug mach altered, or any of tba
tisBuea destroyed." He also takes ocoaaion to ohaerve, "that
tissues immersed in water are destroyed by even moderate
pressure-, but that iu a viscid medium (such as glycerine or
Bjrnp) the requisite pressure can be borne not only without
injury or impairment of the discrimination of their parts,
hut with advantage to their detail." One very great advan-
tage which results from the use of glycerine for the prepara*
tion of texturfS ia, that however they may swell in it after
prolonged immersion, a aofflcient soaking in water will
always restore them to their normal condition, Anoth
that on account of its very high refractive power, it ia
peculiarly fitted for the preparation of struoturea to be ii
veetigated by polarized light, with the same advantage as i
the preceding caae, that they are still amenable to all other
modes of inquiry.

The caustic alkalies — potash, soda, and ammonia
solvents of all animal textarea except chjtine, and perhaps
bone. As in nearly all caaea a softening action, with little
or no alteration of tissue, precedes the solvent action, theae
agents, end especially the first two, have tlieir uses. Under
their influence " a condition is induced very favourable tO'
the imbibition of water, which afterwards penetrates very
rapidly, so that cells swell np and burst." T bey may bo
used either with or without beat, and more or lesa dilute.
There is one disadvautage attending their nee, that objects
can with difficulty be preserved after soaking in them.

Heat, applied either by the aid of hot water or steam, o
the aand-bath, or a bath of fusible metals, or of melted lei:d,
is a very efficient means of softening horny substanaeB, whale-

Ot MICROSCOPIC OBJECTS. 15

Tjone, Ac, and rendering them plastic. Very thin laminw of
these Bnbstannes luaj also be procared by the employ m I'll t
of a well-sharpened scraper, each as that need by cabinet-
mabera. This plan applies laore to longitndinal than to
transverse sections^ yet even the latter may be obtained by
finog the object while soft in a piece of hard wood, and
Gcraptng both together. Long continued slow boiling softens
and eventnally disintegrates nearly all aninial and vegetable
tissDes. Muscular fibre aod many other textores may thas
he isolated, such as spiral vessels, &e., in vegetables.

Prolonged maceration in water, for the preparation of
anatomical stroctnres, generally bony, is a process too well
known to need description here. The addition of very
dilate nitric, hydrochloric, and acetic scids is much em-
ployed for the separation of mnscular fibres, both striated
and smooth. Two or three days are required, or even more.

^ails may be softened very qoickly by hot concentrated
Bolphoric acid — or, still better, by liqoor potaspEB, strength
about 25 to 27 per cent.~so as to show isolated and dis-
tended cells by solution of the intercellular aubatance.

Bones are softened, i.e. decalcified, by boiling or, atill
better, by slow maceration in weak solutions of nitric and
hydrochloric acids, by the action of which the phosphate
and carbonate of lime may be entirely removed. This pro-
cess isolates the animal matter, i.e. the osaeine— sometimes
miscalled gelatine — with all its peculiar fibres and processeSi
Bat bones may be treated in another way, so as to ahuw or
isolate the hone corpuscles with their processes, by removal
or destruction of the intercellular sobataDca. Though this
can scarcely be called softening them, yet it may be most
fitly mentioned here. For this purpose, a Papin'a digester
ia DMeseary. When the boiling of bones has been for a long
|time carried on by means of one of these machioes, they
^seetn to be dissolved ; hut on examination a coarse powder,
COBBiHting of the isolated corpuscles and their processes, ia
fotmd at the bottom of the vessel, which wilt amply repay
the trouble of eiamicatioQ,

16 PHEPAJLATION AND MOUNTING

Teeth may be treated in the same manner as bone0, except
for the examiDation of the enamel, which is best effected by
sections and grinding. For that purpose developing teetii
sbould be chosen, as in them the enamel prisms are most
easily isolated.

5th Division.

As the solution of animal and vegetable tissues generally
means the confusion or destruction of their histological
elements, not much can or need be said of it here, except
that it may be as well to indicate the special solvents and
tests of the special components of all tissues, since it is upon
a correct knowledge and appreciation of the degrees and
differences of the action of these, that effective histological
research must chiefly depend.

Albumen, when pure, is nearly insoluble in water, wholly
80 when coagulated by heat. In dilute caustic alkali it
dissolves with facility. Solution of nitrate of potash, acetic
and tri-basic phosphoric acids, and pepsine, dissolve the pur-
est form of albumen procured from white of egg.

Fownes observes, " that it must be remembered that a
considerable quantity of alkali and very minute quantities
of the mineral acids, prevent coagulation by heat, and that
the addition of acetic acid, indispensable to the test by mer-
cury, produces the same effect."

Fibrin e of blood is insoluble in both hot and cold water,
but is partly dissolved by long-continued boiling. Fresh
fibrin e, wetted with concentrated acetic acid, forms after
some hours a transparent jelly, which slowly dissolves in
water. Yery dilute caustic alkali dissolves fibrins completely.
Phosphoric acid produces a similar effect. Fibrine of flesh,
which is not identical with that of blood (Liebig), is soluble
in cold water containing one-tenth of hydrochloric acid.

Casein is only soluble in water in the presence of free
alkali in very small quantities. It is partly soluble also in
very dilute acids.

OJ KICHOSCOPIC c

17

Gelatin, chondrin, and OBseine are the result of tlie bolliog
of animal membranca, Btin, tendonp. and bonea, respectively
1 high temperatare for a sufficient time. Thej aru
inaoloble in cold water, but easily diasolved bj the nse of
heat. Alcohol, corrosive Bnblimate in eicesB, nitrate of
mercnry, and, most characteristically, tannin, precipitate
gelatine — -the latter when it is very largely dilnted.

" Sliin and tendons contain aGnbstaacu which resists the
action of boiling water for many hours. It is iosoloble in
cold concentrated acetic acid, bat by long- eon tinned boiling
in it, ia ^adnally dissolved, and more easily in hydrochloric
acid." (Fowoes.)

Horny aobstance — ieratin, fonnd ia hair, nails, feathers,
and epithelium, is obtained by finely dividing them, treat-
ing them with hot water, and afterwards by boiling alcohol
and ether. The horny substance is then Tery Bolnble in
canBtic potash.

Of bonas we have already spoken.

It baa been mentioned elsewhere in this work, that all
tie internal organs of insects may easily be dissolved out by
Iwiling in liquor potastie, leaving their external cbitinoaa
stractnres, limbs, &c., unaffected. Bat this is a proceediDg
mncb. to be deprecated, for various reasons which it ia
scarcely necessary to give here. It ia far better to treat
them in another way, by which these organs may be cr-
amined w aifv, at least to a Tery great extent, as will
presently be shown.

The parenchyma of leaves and many other vegetable
stmcturea may be decomposed by prolonged maceration in
watar, and then easily be washed away. Nitric acid, vary-
inglj dilated, will pradace the same effect more speedily, the
objeota not r^quiricg the same amount of bleaching snhse-
qnently. But by far the best and most speedy method is,
to place them in the liqnid manure tank of the gardener
for a sufficiently long maceration. The results of this plan
■re eiqnisitely beautifol.

6th Div'aioN.

The proper eolventa of cakareona animal matters ars
nitric, bydrochlocio. and Bnlphuric acida. The earth of
bones conaista of a combination of two tribaeic phoaphatM
of lime, both of which are entirely soluble in nitric aoS
hydrochloric acids. Salphnric acid abstracta a part of thi
lime of bones, learing a aaperpboaphate — -a aabatance mnoli
nsed in agricultare aa a manure. Flaoride of calcium,
existing in small quantity in bones, bot ia larger ii
enamel of teeth (and of the ganoid acalea of fish P), ia do-
composed by Bnlphario acid, which combines with the cal<
cium, allowing the hydrodaoric acid to 9y off in a, gaseous
state. Carbonate of lima diasolvea in nitric and hydro*
chloric acids. The abella of mollusca, and testte of echino-
dermata, oonsiating principally of carbonate of lime, ari
Bolublo in the same acids, as well as those of nnmmnliteS
foraminifera, &a., which have been infiltrated with eiliceoas
matter. These present the most beautiful " casta," whioli
are exactly of the shape of the Sarcode body and canal sys-
tem, thns enabling their internal organa to be atudied witi
much accuracy. Dr. Carpenter aaja that they are of "
derfnl completeness."

7th Divbiok,

Silica is nearly altogether insoluble id water, but dissolTe*
freely in strong alkaline solntions. Its only acid solvent ii
hydrofluoric acid. Its combinationa with a larger proporti
of alkali are soluble in water, and from such solutions ailioc
may be precipitated in a gelatinous or colloid form bf
Bcida, or separated by dialysis, in the form of colloid silica.
This Bubstance may be used for procuring certain modifica-
tions of cryatala of aalta for the polariacope, anch as anlphats
of magnceia, sulphate of copper, boracic acid, sulphate of
&c. In its combination with a smaller proportion of alkali,
forming glass, it is attacked by hydrofiuorio acid and Jla
vapour, and advantage may be taken of this property ta

ECTS. 19

engrave tiBmea, nitnibera, tc., neaUj opon sUdea, far dassifi-
c^on in tbe cabinet. The g-Issa to be eogrsTed must be
ooftted wilL in etching pronnd of oily varnish or wax. and
the upceasajj writing efiecl^d upon it bj a point, which
UQst pierce tfarongh the prot«cIJ*e dat^rial. A ehallow
bauD, made bj l^sdiiig up the edges of a piece of sbeet-lead,
is then prepared, a little powdered £iior epar placed in it,
and enoagb salphnric acid added to form a thin paste. The
g]aet is then placed in any oonvenient way over the basin,
the waxed side don^wards. A gentle heat ta next applied,
whereby the vaponr of hjdroflooric acid is disengaged. This
acta upon the glass exposed by the point in a very few
minatee, removing a portion of ite surface. The icai most
thea be removed by tnrpentJiie. If the lioes which result
are then robbed over with any colonred vamish, and the
Tarnish gently wiped off bj a soft piece of rag, a sufficient
portion will most probably remain in the etched marks to
render them easily visible and legible. Of conrae it will be
as well to prepare eaaoy slides in this way at once. It is not
neceBBar; to coat the whole sarf&ce of the slides with the
jirotectiTe varnish, if the leaden basin be covered with a
thin piece of wood or sheet-lead perforated with holes
slightly larger than the sarface to be etched, over which
holes Uie slides mnst be inverted for a snffiuicnt time. This
latter hint applies more particularly to finished slides requir-
to be labeUed.

8th Ditisios.

The proper solvents of the fiiod oily and fatty matters
lie ether, benzole (or benzine), turpentine, and the essen-
tial oils generally. Castor oil is nearly the only one which
18 Milnble in aleofaol, the rest being only slightly so, Tbey
are all capable of saponification with oaaetio alkalis, and so
become indirectly soluble in soft or distilled water, other-
wise tbey are wholly insoluble in it.

The volatile or essential oils mix in all proportions w
&tty oils, and are wholly soluble in ether and ale
c2

20 PBEPABATION AND MOUNTING

Campbor dissolves in a only very small proportion in water,
but freely in alcohol, ether, and strong acetic acid.

9th Division.

It is by no means intended to speak here of the general
properties and uses of polarized light. Bat in relation to
its special powers in the ** differentiation " of tissues, there
is very mnch to be learned. To be fitted for examination
by this method, objects must be made more or less trans-
parent or translucent ; and in effecting this it is advisable,
perhaps necessary, to employ media of high refractive power.
Even when so prepared, it may be further necessary in some
cases to employ seleoite or mica films, still more to enhance
their colour. Not the least indication can be afforded to the
observer as to what colours he should employ generally, yet
it is a matter of frequent observation that what are called
•* neutral tints *' are to be preferred, such as result from the
judicious use of compound selenite stages adjusted properly
for that special effect.

The media mof^t suitable for the preparation of objects to
be examined in this way are glycerine, syrup, turpentine,
dammar and benzole — or the latter alone, Canada balsam,
and the essential oils. Of course sections must be made of
.tissues otherwise too thick. Of the advantages of employing
the first of these we have already spoken ; but to these must
be added this important one, that it does not spoil the object
for examination by other methods, if the gljcerine be soaked
out by maceration in water; and this is true also of syrup,
though it is far less useful. For preparation by the other
methods, tissues must have been soaked in alcohol, and then
removed into the turpentine, &c.

For the examination of insects by polarized light, two
preliminaries are necessary. Firstly, that they be made
transptirent or translucent by prolonged soaking in one of
the above-named media, preferably in turpentine or the
essential oils, or benzole. Secondly, that as in (mostP)
many of them their chitinous case is too deeply coloured for

or MICROSCOPIC OBJECTS. 21

any araannt of soaking to render them BnfficiEntl; trans-
parent, same hleaching prooesa ahoalJ l>e premised, A for-
mnla for such a process may be fiionil ia another part of

~ a work, where the preparation of the autennKt of iasecta
is dpSDribed. If that shoald not prove Bucoositfiil, some
raodificattoQ will easilj occur to tlie student. Of coiirae it
at all insects that can he treatiid in this way, the siaie
and deep colonr of very many quite preventing a good
result; bat when they have been BncceaBfully prepared by
any of the methods of which we have apoken, it ia thea
possible to discrimioate their internal organs by the differ-
ences of colour which they preaent. The nse of the binoonlar
microscope, and of objectives of low angnlar aperture, will
also iDQab facilitate thia mode of examination, by i[
the depth of focus, and enabling the organs to be ai
or leas in connection with each other, even if they be super-
posed, lb is also poasible to eramine the mnaclus of the
limbi and bodies of insects, so as to decide upon their forma-
tion, origin, and insertion, and probable mode of astioti; and
is only one of many sach nsea. What a mistake most
it be, then, to prepare insects for monnting by boiling in
liqaor potassro, and so disaolving out their viscera, and
squeezing them flat!

In the case of living insects, especially those of the mora
tranaparent salt and fresh water species, the reaalts of their
examination by polarized light are exqnisiti^ly beautiful and
interestiug, becanse their organs and circulation may be

nore olearly discriminated while in motion.

10th DivisiOK.

Eleotrioity has been employed in histology partly for its
electrolytic effecta, but chieQy as a means of producing
Mitain variations of temperature in objects under eiamina-
tion, Strieker saya " that the tiasues become altered by it
aa they wonld be were they subjected to the action of weak
acids or alkalius," and ho describes a rather complicated
apparatus for thia purpose, of which it is impoBsible to giva

22 PSErAfliTioN ASD MOUKTtso

an account here ; bnt the anthor believea that moat, if not
aX, of tbe Bame effects maj be prodnced b; (he emplojmeQt
either of a thick plate of metal placed upon the stage, o
a thin water-bath, which may be heated by a spirit or _
flame, after the glass slide shall have been placed on it.
Tbey sliODld both be properly fitted with therm ometere.

Of the decomposition of salts by electricity, and their n
daction to the metallic state, it is not necessary to speak
here, bat such effects are very hcautifal, and the resulting,
crystal ization may easily be watched.

Dr. Beale speaks very favoarably of the inverted i
Hcopa devised by Dr. Lawrence Smith, TJ.SA., by whidi
objects may be viewed from their ander instead of from their
upper suiface, and at Iho same time heated (or re-agents
applied to them) withont any risk of dimming or ioj
the object-glass by vaponrs thns raised. The optical part
ia so fitted to tbe base that in may be drawn away from be-
neath the stage (to make room for the application of the
lamp, or) for the sake of changing the powers.

IIth Division.

It is evident that in all theKe plans an amoant of evapo-
ralioQ is constantly going on, nhich will eventually dry and
80 spoil the objpct, unless obviated. Frey, therefore, desoribei
a "moist chamber" invented by Eecklinghansen for this
purpose. It consists of a glass ring, more or less high,
which has been cemented by its edge to a broad glass slide.
A tube of thin rnbber is then firmly fastened about the nog.
Tbe upper end of this tnbe is also fastened around the tuhfl-
of tbe microscope. In order to keep the place thus enclosad
saturated with moisture, some small pads of wetted bibulooa
paper, or pieces of elder pith also saturated with fluid, i
be enolosed with the object, which in this ease need not be
covered with thin glass in the usual manner. It is
ceivable &lso that this apparatus may easily be converted
into a gaa chamber, by fixing two small, light valoanizsil

OP HICBOSCOPIC OBJ£CTS« 23

tnbes into tbat which embraces the glass ring and the end
of the microscope tube — one for the entrance, the other for
tbe exit of the gas. This is a simpler and less costly plan
than that devised bj Strieker, Frey observes that it is
most advantageous to nse immersion lenses and the moist
chamber v^ith the hot stage.

2-4 PHEPAJULTION AND MOUNTING

CHAPTER II.

APPABATUS.

Before entering into the subject of the setting of Objects
for the Microscope, the student must be convinced of the
necessity of cleanliness in everything relating to the use of
that instrament. In no branch is this more apparent than
in the preparation of objects ; becanse a slide which would
be considered perfectly clean when viewed in the ordinary
way is seen to be far otherwise when magnified some hun-
dreds of diameters ; those constant enemies, the floating
particles of dust, are everywhere present, and it is only
by unpleasant experience that we fully learn what deanU'

71688 is.

An object which is to be viewed under the microscope
must, of course, be supported in some way — this is now
usually done by placing it upon a glass slide, which on
account of its transparency has a great advantage over
other substances. These ** slides " are almost always made
of one size, viz., three inches long by one broad, generally
having the edges ground so as to remove all danger of
scratching or cutting any object with which they may come
in contact. The glass must be very good, else the surface
will always present the appearance of uncleanliness and dust.
This dusty look is very common amongst the cheaper kinds
of slides, because they are usnally made of " sheet " glass ;
but is seldom found in those of the quality known amongst
dealers by the name of " patent plate." This latter is more
expensive at first, but in the end there is little difference in
the cost, as so many of the cheaper slides cannot be used
for delicate work if the mounted object is to be seen in per-
fection. These slides vary considerably in thickness j care

ot MICROSCOPIC OBJECTS. £5

bIioqU, tberefare, be taken to sort tLem, bo that tlie more
delicate objectH with which the higher powers are to be
TiBed maj be mounted apon the Ihhiuest, an the light em-
ployed in the illumination ia then less interfered with. To
aid the microscopiat in this work, a metal circle may be pco-
cored, having a number of different sized openings on the
oater edge, by which glasa slides ciin be measured. These
(^ninga are numbered, a.nd the slides may be sepiiruted
tUKMirding to these nambersj so that whea mouctitig any
object there will he no need of a. long search for that gkse
which is best saited to it,

When fresh from the dealer's bands, these slides are
generally covered with dual, &<;,, which may be removed by
well washing in clean rain-water; bat if the imparity is
obstinate, a little washing soda may he added, care being
taken, however, that every trace of this ia removed hy aub-
saqnent waters, other<iviee, crystals will afterwards form npon
the Borface. Sometimes, however, a certain greaaiaeBa ia
very ohatinate opoii the glaaa. It ia then necessary to uae
B little liqnor potaasao with a small piece of linen, rubbing
tfae slide with some pressure, and then washing as before to
remove all remains. A clean linen cloth should be used to
dry the slides, after which they may be laid by for nee.
Immediately, however, hufore being naed for the reception of
ohJeetB by any of the following proceaaea, all dust must be
removed by rubbing the surface with clean wash-leather or
B piece of cambric, and, !/ needful, breathing npon it, and
then Dsing the leather or cambric nntil perfectly dry. Any
Bmftll particles left upon the surface may generally be
removed by blowing gently upon it, taking care to allow no
clarop to remain. A very efficient remedy, also, is a mixture
of equal parts of sulphuric ether and alcohol, with which
the glass must be rubbed by the aid of a tuft of clean
eottoQ-wool until no stain oppeara after breathing upon it,
A strong infusion of nutgalls may be used in the same way,
and is preferred by many to all other applications; or, a
mutture of equal parts ot alcohol, benzole, and liquor sodw

Pi RATION AND MOUKTIXG

may be employed, irhicb tborongbl; and speedily cleaneec
glass from all traces of greaae or bulaam.

We ha»e before said thftt any olgVct to be viewed in tbi
TDicroGCope miat have its snpport; bat if this object is to
be preeerved, care mnat be takea that it ih di^fended boat
daat and other imparities. For this pnrpoBe it ia necee
to nae aome transparent cover, the most uenal at one
being a plate of mica, on account of its thinneBS; this
stance ia now, however, never naed, tbiti glaes being Bubsti^
toted, which anawers admirably. Some^mfa it ia required
to " lake lip " aa little apaoe aa posBible, owing to the short
neBB of focna of the object-glaasea. It can be procured a
any thiulcness, from one-fiftietb to one-two-bnndred-aiid'
fiftieth of an incb. On a:Cconnt of its want of etrengtb, aw
probable defect of due annealing, it is diScoIt to cnt, as i
ia very liable to "fy" from the point of the diamond. Ti
overcome this tendency as much as possible, it must be laij
upon a thicker piece, previonalj made wet with water, nbioh
caasea the thin glass to adhere more firmly, and oonso
qnently to bear the pressnre required in cutting the d
The proceaa of catting being so difSeult, especially with tU
thinner kinds, little or nothing ia gained by cutting tho*
which can be got from the dealers, as the loss and breafcag
ia necessarily greater in the bauds of an amateur. It i
convenient, however, to have on hand a few larger pieoeK
from which nnusnal sizes may be cat when required.

If the pieces required are rectangular, do other apparatni
will be required aave a diamond and a flat role ; but I
inVc'es are wanted, a machine for that purpose ahould b
used (of which do descriptiou is necessary here). There aro)
however, other contrivances which answer tolerably well
Ono method is, to cat out from a thick pipce of cardboard i
circle rather larger than the aize wanted. Dr. CiirpeotSI
recommeuds metal rings with a piece of wire soldered on
either side ; and this, perhaps, ia the best, aa cardboard is
apt to become rough at the edge when much used. A friea^
of mine Dses thin brass plates with circlea of varioas eieet'

OP SaCEOSCOPIC OBJECTS.

27

" turned " throagli them, and a smiLlI raised handle placed
at one end. The diamood muet be passed rouod the inner
edge, and so managed as to meet again in the same line, in
order that the circle may be trne, after which it may be
readilj diaeogaged. The sizee naaally kept in atock by the
dealers &re one-hair, Sve-eighthB, and three-quarters inch
diameter ; but other sizes may be had to order.

For the JDformation of the beginner it raay be mentioned
here that the price of the circles ia a little more than that
of the eqoares; but this is modified in some degree by the
circles being rather lighter. If appearance, however, is
cared for at all, the circles look mnch neater upon the slides
when not covered with the ornamental papers ; but if these
last are naed (a« will shortly be described) the squares are
equally serviceable.

As before mentioned, the thin giaas \e made of various
thicknesses, and the beginner will wish to Icnoiv which to
nae. For objects requiring no higher power than the one-
inch object-glaes, the thicker kinds serve well enongh ; for
the half-inch the medium thickness will be required ; while,
for higher powers, the thinnest covers must be used. The

' " test-objects " for the highest powers require to be brought
so near to the objeot-glaas that they admit of the very
thinnest covering only, and are usually mounted betwixt
glasses which a beginner would not be able to use without
ft-eqnent breakage ; but if these objects were mounted with
the common covers, they would be really worthless with the
powers which they require to show them satisfactorily.

It may be desirable to know how such small difTerencea
as those betwiit the various thin glass covers caa be
measured. For this purpose there are two or three sorts of

J apparatue, all, however, depending npon the same principle.

I The description of one, therefore, will be snfScient. Upon a

1 Hoall stand is a short metal lever (as it may be termed)
which returns by a spring to one certain position, where it
ia in contact with a fised piece of metal. At the other end
tbis lever ia connected with a " Eager," which moves round

28 PBEPARATION AND MOUNTING

a dial like tliat of a watcb, whereupon are figures at fixed
distances. When the lever ia separated from the metal
which is stationary, the other end being connected with the
" finger," of the dial, that " finger " is moved in proportion
to the dintance of the separation. The thin glass is, there-
fore, thrust betwixt the end of the lever and fixed metal, and
each piece is measared by the figures on the dial in stated
and accurate degrees. This kind of apparatus, however, is
expensive, and when not at our command, thin glass may
be placed edgewise in the stage forceps, and measured very
accurately with the micrometer, or by the calliper eye-
piece described by Dr. Matthews in No. 8, for October, 1869,
of the Journal of the Quekett Microscopical Club.

Cleanliness with thin glass is, perhaps, more necessary
than with the sides, especially when covering objects which
are to be used with a high power ; but it is far more difficult
to attain, on account of the liability to breakage. The
usual method of cleaning these covers is as follows : — Two
discs of wood, about two inches in diameter, are procured,
one side of each being perfectly flat and covered with clean
wash-leather. To the other side of these a small knob is
firmly fixed as a handle, or where practicable, the whole
may be made out of a solid piece. In cleaning thin glass,
it should be placed betwixt the covered sides of the discs,
and may then be safely, rubbed with a sufficient pressure,
and so cleaned on both sides by the leather. If, however,
the glass be greasy, as is sometimes the case, it must be
first washed with a strong solution of potash, infusion of
nutgalls, or any of the commonly used grease-removing
liquids; and with some impurities water, with the addition
of a few drops of strong acid, will be found very useful, but
this last is not often required.

This method of cleaning thin glass should always be used
by beginners ; but after some experience the hand becomes
80 sensitive that the above apparatus is often dispensed
with, and the glasses, however thin, may be safely cleaned
betwixt the fingers and thumb with a cambric handkerchief.

OF MicROsconc OBJECTS. 29

haTing Erst Blightlj danipod the enda of the fingers employed
lo obtain firm bold. When the dirt is very obstinate,
breathing npon the glaea greatly faoililatea ita removal, and
the sense of touch becomes ho delicate that the breakage is
iocon aid arable ; but tbia method cannot be recom mended lo
tmricea, as nothing bnt time apeiit in dolicate maQipaltktioa
can give the aeoaitiveneas required.

It has been before mentioaed that ordinary glass sidesi aro
Bometiniea wortblesa, etpeciallij for fine obj-cig, from having
a rough snrfuce, whicb preaents a dasty appearance nnder
the microaeope. Tbia imperfection eiists in some tkiii glass
bIbo, and ia irremediable; so that it is tiaelesa to attempt to
cleanse it; nevertheless, care ehonid be taken not to miatake
dirt for this ronghness, lest good glass be laid aside for a
&iilt which does not really belong to it.

When any object whicb it is desired to mount ia of eon-
riderable thickness, or will not bear pressure, it is evident
tLat a wall must be raised aronnd it to sopport the ttiin
g'aea — thia is naually termed a "cell," There are various
deacriptiona of these, according to the class of objei:ts they
are required tn protect; and here may be given a description
Cif those which are most generally used in mounting "dry"
objects, leaving those reqnirpd for the preservation of liquids
until we come to the consideration of that mode of mounting.
Uany havB need the following slides. Two pieces of hard
wood of the naual size (3 in. by \ in.), not exceedini{ one-
sixteenth of an inch in thiekness, are taken, and a hole ia
Qien drilled in the middle of one of these of the size required.
The two pieces are then onited by glcie or other cement,
and left under pre.isnre until thoroughly dry, when the cell
is fit for use. Others substitnte cardboard for the lower
pieae of wood, which is less tedious, and is strong enough
for every purpose. This class of "' cell " is, of conrse, fitted
for opaque objects only where no light ia required from
below i and aa almoat all such are lietter seen when on a dark
backgrODud, it is usual to fix a amull piece of black paper
ftt the bottom of the cell upon which to place them. For

30

reiy Rmall objectB the grain whicli all each paper h
vfaen magnified detracts a little from the merit of tl
backgraand; and latelir I have used a small piece of thiA
glaea covered on the back with black varoish, and placed thl
object upon the smooth □□toacbed aide; but a Bolution of
the best Egyptian asphalt ia benzole of moderate thick*
neiB msj be painted on with this further advantaga,
that in mountiog Buch opaque objeuts aa fursmioifera, iiA,
it will be Buffioient to arrange them in the positiooa thef
are to occupy, when by elightly narmiog the slide thsf
will adhere to the asphalt.

Another method of making these cells ia aa followa ;— ^
Two puncbeR, similar to those nsed fur cutting gun-wadSi^
are procured, of such sizes that with the smaller mav be cati
out the centre of the larger, leaving a riug whose side is i
less than an one-eighth of an incli wide. Tbeae rings ma/^
be readily made, the only difficulty being to keep the side*,
parallel ; but a little care will make this easy enough. ~~
this purpose close-grained cardboard may be coaTeniently
DHed. It moat have a well-glazed surface, else the y
t t>r cement used in affixing the thin glass cover ainks into tbfl
■'Substance, and the adherence is very imperfect. When tbil
I takes place it is easily remedied by brushing overt"
face of the cardboard a strong solution of gum c
glass ; and tliia application, perhaps, closes also the porefl
of the card, and so serves a doubI(3 purpose. Bat, oC
course, the gum must be perfectly dried before the ring i

For cardboard, gutta-percha baa beeu substituted, bi)|
cannot be recommended, as it always become brittle aft4
a certain time, never adheres to the gloss with the required
firmness, and its shape is altered when worked with e
little beat. Leather is often used, and is very convenient)
it should be chosen, however, of a close textnre, and frei
ii-oni oil, grease, and all those snbstances ivhich are loii
upon it by the dressers.

Bings of cardboard, Ac, have beeu rejected by persons oi

ot aiCBosconc objects. 31

great esperieoce, beoaaaa they are of suuh a nature tliat
dampneas can penetrate them. This faalt can be almoat, if
not totally, removed by imraeraing tbem in aome strong
vamiah, each as the aaplialt Tarnish hereinafter mentioned;
but they must be left long enongh when affixed to the glasa
alide to become peifectly dry, and this will rec[uire a maoh
longer time than at Qrst would be BUppoaed.

There haa, however, been lately brought ont what ia
termed the ivory cell. Thla is a ring of irory-lilcQ subatiince,
vhicb may be easily and firmly fixed to the glaaa alide by
any of the commonly need cements, and ao forma a beautiful
cell for any dry objects. They are made of different Bizea,
andarenot expcnaive. Flat rings of brass torned down to the
eizea of the oircular diaca of covering glasa and of varying
tbiokneas are very neat and useful for monnting opaque
objects: they can also be obtained in tin and zinc.

Some of our beat microacopio men have stated that they
have bean freqnuntly diaappointed by an accumulation aC
enorUBted matter npon the inner surface of thin gliias uaed
to cover the cell enclosiag any dry object, and therefore nae
a shallow pillbox, made exprsaaly for thia pnrpoao, which
maat be atroogly cemented to the alide. For examination,
the lid must be removed, whilst it must be closed to proteob
the object from dust when laid aside. Another worker of
experience reoommenda a cell in a mahogany slide, over
which, by aid of a atud aa on a pivot, a bone disk can be
turned: thia ia termed, "Pipec'a Revolving Cover Slide,"
and can be procured at the opticiana'.

Sometimes slides are used which are made by talcing a
thin alip of wood of the usual size (3 in. by 1 in.), in the
centre of which ia cnt a circular hole large enough to
receive the object. A piece of thin glass ia Gxed underneath
the shde forming a cell for the object, which may then be
covered and finished like an ordinary slide. This hiia the
advantage of serving for transparent objecta for which the
before- mentioned wooden alides are unsuitable. A alight
modification of this plan ia often used where the thickueas

32 PEEFABATION AND MOXTNTniO

of the objects is inconsiderable, especially with some of tlie
Diatomaceas, often termed "test-objects." The wooden
slide is cut with the central opening as above, and two
pieces of thin glabs are laid npon it, betwixt which the
diatoms or other objects are placed, and kept in their proper
position by a paper cover. This arrangement is a good
one, insomach as the very small portion of glass through
which the light passes on its way to the microscope from
the reflector causes the refraction or interference to be
reduced to the lowest point.

A novice would naturally think the appearance of some
of the slides above mentioned very slovenly and nnfinished ;
but they are often covered with ornamental papers, which
may be procured at almost every optician's, at a cost
little more than nominal, and of innumerable patterns and
colours. How to use these will be described in another
place.

It is very probable that a beginner would ask his friend
what kind of slides he would advise him to use. Almost
all those made of wood are liable to warp more or less, even
when the two pieces are separate or of different kinds ; those
of cardboard and wood are generally free from this fault,
yet the slides, being opaque, prevent the employment of
the Lieberkuhn. To some extent glass sides, when covered
with ornamental papers, are liable to the same objection,
as the light is partly hindered. And sometimes dampness
from the paste, or other substance used to affix the papers,
penetrates to the object, and so spoils it, though this may
be rendered less frequent by first attaching the thin glass to
the slide by some harder cement. Much time, however,
is taken up by the labour of covering the slides, which is a
matter of consideration with some. Certainly the cost of
the glass slides was formerly great; but now they are
reasonable enough in this respect, so that this objection is
removed. It is, therefore, well to use glass slides, except
where the thin glasses are employed for tests, &c., as above.
When the thin glass circles are placed upon the slides, and

scTS. 33

the edge ia varaislied witli black or coloared rings, the
ftppearance of fiaisfa. is perfect. The trouble is mach less
Uiau with most of the other metliods, and the iUamiuation
of the object very slightly impaired.

To TBrniBh the edges of these coTers, make circles of any
liqnid upon the glass slide, and perforoi aoj other circalar
work mentioned hereafter, the little instrument known as
Shadbolt'a .turntable " is almost indiEpensable. It ia made
9 follows ; — At one end of a Bmall piece of hard wood is
fixed an iron pivot about one-eighth ioch thick, projecting
lialf an inch from the wood, which serves as a centre npon
which a ronnd brass table three inches in diameter revolves.
On the snrf^ce of this are two springs, abont one and a half-

■h apart, under which the slide is forced and so kept in
position, whilst the ceutral part is left open to be worked
npon. The centre is marked, and two circles half an inch
inch in diameter are nsuallj deeply engraved npon
the table to serve as gnides in placing the slide, that the
ling may be drawn in the right position. When the slide
is placed npon the table underneath the spricgs, a camel-
lair pencil is filled with the varniHli, or other medium used,
and applied to the surface of the glass; the table is then
made to revolve, and a circle is consequently produced, the
diameter of which it is easy to regulate, Mr. Hislop places
two equidistant pins at opposite sides of the centre of
revolving plate, against which the opposing edges o<
the slip are made to bear, so tbiit the instrument is self-
centering. The springs are turned in contrary directions anil
ore screwed on the plus, or the screws are made into tho
pins against which the sides of the slide bear.

The form of this " turntable " bus been modified by many

anipulators to anit their several wants. Almost all slides
nsed are of nearly the same size — 3 in. by 1 in. ; and therefore
the centres of all are equidistant from the edge. On this
account one of my friends has a thin brass bar screwed upon
the side of his turntable in such a position that the centres
of the slides and table alsvays coincide. The rings of varnish

S4

upon the slides and tbia glass upon the cell are thus Vept
■uniform. Dr. MatthewB, u gentleman of no little eiperience,
has giTenuB an improTemont as followB ;■ — Take two " '
of tlie average thickneaa of a glaas slide, f inch wide, 2^
long. Each of theae ia pivoted on the face of the tomtable
by a screw throagh its centre, each screw being placed
esactly eq^nidiatant from the centre of the tnrntable, so tHat
the jaws are separated by a space aa wide aa'an average
elide ; i.e. a full inch. Oatside of that space, on one aide of
the centre of one of the jawe, is a wedge fixed by a acre
Buch a way as to bo capable of motion in the direction of
its length by a alotted hole. This is all the machinery,
AB and CD are the two j'awB, E is the wedge. On placiDg
a, slip between the jaws they probably at first do not toaeh
it. If the wedge be then pashed so as to approximate B to
C, the jawB move on their centres, so that, however far B
may be pnahed towards (and moving) C, the other end of
— i.e. J) — is moved exaMy as much in the opposite direC'
tion nntil they approach near enough to grasp the slide by
its edges. The length of the wedge mnat, of oonrae, be such
BS to provide for about \ inch variation in the width of
elides. It will readily be seen that the slip may be pushed
in either direction eicentricaliy lengthwise, bo aa to allow of
the formation of any nnmber of cells, all of which mast
needs be central as regards their width, if the instrament
has been accnrately made, which is a very easy matter.
have added also a rest for the hand, F, which may be turned
aside on a centre at will, and which I have found to be a
j^reat convenience.

:•*

OT^

;CBOSCOn^

OTiJl'^^^'

\

36

PBEPABATION AND MOUNTING

Mr. SpeDcer sliglitlj modifies tlie aboTo, using wood
jaws and wedge, which the following engraving will best
explain.

DE. MATTHEWS* TURNTABLE, TWO-THIKD SIZE.

Many objects for the microscope may be seriously injured
by allowing the fingers to touch them — many more are so
minute that they cannot be removed in this way at all, djA
often it is necessary to take from a mass of small grains, as
in sand, some particular particle. To accomplish this, there
are two. or three contrivances recommended : one by means
of split bristles, many of which will readily be found iB
any shaving-brush when it has been well used. The bristles
when pressed upon any hard surface, open, and when the
pressure is removed close again with a spring ; but the use
of these is limited. Camel-hair pencils are of great service
for this, and many other purposes, to the microscopist.
In very fine work they are sometimes required so small that
all the hairs, with the exception of one or two finer pointed

OF MICROSCOPIC OBJICTS, 37

inea, are reni07ei]. A few of Tarioug Bizea should alwaje be
:ept on hand.

Equally ncocflaary ai'e fioe-pointed neeillea. They are
very readily put np for nae by thrusting the eye end into
a penholder, bo as to he firm. The points may be
readily renewed, when iojared, on a common whetstone ;
of aae they may be protected by being thruat
into a piece of eorV.

la laying oat animal tieanes that have been stained by
iiitrate of silver or chloride of gold, it is advisable to employ
I Hmal! rod of glass drawn out to a point, as the use of a
ooetallio point eauaes a deposit of gold or ailver at the place
>f contact, which diafigares the preparation.

~ ' ' rarious iiinds are required ia some branches

of microscopic work ; but these will be described where
3isBectioD, &c., in treated at some length, as aleo various
forma of scisaors. In the most simple objects, however,
Bcisaors of the usual kind are necessary. Two or three
jizea should always be kept at hand, sharp and in good

A set of glass tubes, kept in a case of some sort to
prevent breakage, sboald form part of our fittings, and
be always cleaned immediately after nee. Tbese are
generally from six to ten inches long, and from one-eighth
to a quarter of an inch in diameter. One of these should
be straight and equal in width at both ends ; one should be
drawn out gradually to a fine point; another should be
pointed as the last, bnt slightly curved at the compressed
' ir to reach points otherwise nuattainable. It ia
well to have these tubes of various widths at the pointa, as
e waters the finer would be inevitably stopped. For
other purposes the fine ones are very useful, especially in
■ the transfer of preservative liquids which will come under
notice in another chapter.

Porceps are required in almost all microscopic manipu-
lations, and consequently are scarcely ever omitted From the
, microscopic box, even the most meagrely furnislied ; but of

38 PKEPARATION AND MOUNTIXG

these there are varioas modifications, which for certain
purposes are more convement than the nsaal form. The
ordinary metal ones are employed for taking op small
objects, thin glass, &c. ; but when slides are to be held over
a lamp, or in any position where the lingers cannot con*
veniently be used, a different instrument mnst be found.
Of these there are many kinds ; but Mr. Page's wooden
forceps serve the purpose very well. Two pieces of elastic
wood are strongly bound together at one end, so that they
may be easily opened at the other, closing again by their
own elasticity. Through the first of these pieces is loosely
passed a brass stud, resembling a small screw, and fastened
in the second, and through the second a similar stud is
taken and fixed in the first — so that on pressure of the stnds
the two strips of wood are opened to admit a slide or other
object required to be held in position. The wood strips are
generally used three or four inches long, one inch wide, and
about one-eighth inch thick.

Again, some objects when placed upon the glass slide arc
of such an elastic nature that no cement will secure the
thin glass covering until it becomes hard. This difficulty
may be overcome by various methods. The following are
as good and simple as any. Take two pieces of wood about
two inches long, three-quarters wide, and one-quarter thick;
and a small rounded piece one inch long, and one-quarter in
diameter; place this latter betwixt the two larger pieces.
Over one end of the two combined pass an india-rubber
band. This will give a continual pressure, and may be
opened by bringing the two pieces together at the other
end ; the pressure may be readily made uniform by paring
the points at the inner sides, and may be regulated by the
strength of the india-rubber band. These bands may be
made cheaply, and of any power, by procuring a piece of
india-rubber tubing of the width required, and cutting off
certain breadths. Another very simple method of getting
4ihis pressure is mentioned in the "Micrographic Dictionary."
Two pieces of whalebone of the length required are tied

Cr inrrp.nKiTrqr eEXrzs. I^

together firmlj at each eni. Ii s mdecx lih&i £xt Diiifizrt
placed betwixt ihem. wO be Bcipfici uS saTirmfcZ proEcnL
The power of this msj be r&rxLL&:«i Ij line r.V i^jrwro azL^
length of the whaleboine. Tnis Kim^"^ cacizfrcjkK je tctj
nsefnL

Almost ererj mnmmi^-^^. xnsn. Lowers', L&e lie rvrs m^ifl,
and it maj be as wdl to ezamizie oiifr or xwj x tbezc ICr.
Goode uses the foillowizLg: A, a yi^sx of itdic ^ ix. l:aig
and i in. thick. B. a fprzuz zziade ^vriih iiizi irjin "vire.
The end of the fpiing is diiTezi ilio ^be idtlilf::, as a* C. A
piece of ^-in. iron nire is then ran ihiZ'^zh tie Fprlr.gs, irr.icih
fonns an axis to woik upon, ani &Iso keeps iLezi ir ibeir
places. He incerU a pin ai iLe siie cf u.e spiisz, bj that
it will fall on a gxren spot, and zjot r::^ tike i-iTer friiia siie
to Bide. The springa are made Lj bin-^Tng the ih'.Ti wire
round the j-in. rod about fonr or f re l:ipe».

40

VTUB CLIP.

OF MICROSCOPIC OBJECTS.

41

Mr. J. B. Spencer's model is made thtiB : — It is formed
of thio sbeet steel (obtainable at any instium!?nt mater's), acd
cnt ont in one piece, of the form above, with a stoat pair of
SOTS, and then bent the required shape with a pair of
Ts. "When nsed, the fore and middle lingers are applied
the under side, and the thnmb on the spring. If great
pressure la required, two clipa may be nsed, — HDne at each
end of the slide, — -and for any delicate work the tindth of
the steel can be reduced.

I

^

The American wooden epring clips are occasionallj verj
asefol, and wire clips of the kind described by Dr. Carpenter
>n now commonly sold and are indispensable.

Common watch-glasses should always be kept at hand.
Thpy are certainly the cheapest, and their transparency
makes them very convenient reserroirs in which objects may

42 PKEPARATION JlSD MOUNTING

be steeped in any liquid ; and the use of tliem saves mucli
trouble in examining carsorily under the microscope, whether
the air-bubbles are expelled from insects, Sue, &c. They are
readily cleaned, and serve very well as covers, when tamed
upside down, to protect objects from dust. For this latter
purpose Dr. Carpenter recommends the use of a number of
bell-glasses, especially when one object must be left for a
time (which often happens) in order that another may be
proceeded with. Wine-glasses, when the legs are broken,
may thus be rendered very useful.

As heat is necessary in mounting many obejects, a lamp
will be required. Where gas is used, the small lamp known
as "Bansen's" is the most convenient and inexpensive. It
gives great heat, is free from amoke, and is readily affixed
to the common gas-burner by a few feet of india-rubber
tubing. The light from these lamps is small, but this is
little or no drawback to their use. Where gas is not avail-
able, the common spirit-lamps may be used, as they are very
clean and answer every purpose.

In applying the required heat to the slides, covers, &c., it
is necessary in all cases to ensure uniformity, otherwise
there is danger of the glass being broken. For this purpose
a brass plate at least three inches wide, somewhat longer,
and one-eighth of an inch thick must be procured. It
should then be affixed to a stand, so that it may be readily
moved higher or lower, in order that the distance from the
lamp may be changed at will, and thus the degree of heat
more easily regulated. This has also the advantage of
enabling the operator to allow his slides, &c., to cool more
gradually, which, in some cases, is absolutely necessary, —
as in fusing some of the salts, &g.

In order to get rid of air-bubbles, which are frequently
disagreeable enemies to the mounter of objects, an air-pump
is often very useful. This is made by covering a circular
plate of metal with a bell-glass, both of which are ground so
finely at the edges that greasing the place of contact renders
it air-tight. The pump is then joined to the metal plate

OF MICEOSCOPIC OBJECTS.

tiQiIcmeatb, acid worked wttli a email handle lilce a
Bjricge. By tnrning a sraall milled head the air may be
ttllnwed to re-enter when it is reqnired to remove the bell-
glaas and eiamine or perform any operalion uppn the ohject.
The mode of using this instrument will be described here-
after, bnt it may be liere stated that sabstituteB hare been
devised for this naefcil appftratus; hat as it is now to be
obtained at a low cost, it ia hardly worth while to consider
them. Much time is, in many inetaiices, certainly saved by
its use, as a very long iminersiou in the liquids would be
reqnired to eipel the bobbles, where the air-pump would
remove them in an hoor.

The next thing to be considered is what may be termed
Cements, some of which are neeeasary in every method of
monnting objects for the microscope. Of these will be given
the oompoailion where it ie probable the young student can
use it ; but many of them are so universally kept as to be
obtainable almoet anywhere; and when small quantities
only are required, economy suffers more from home maou-
faotnre than from paying the maker's profit.

Amongst these, Cakada Balsam may, perhaps, be termed
the most necessary, as it is generally used for the preserva-
tion of many transparent objects. It ia a thick liquid resin
of B light amber-eolonr, which ou exposure to the atmosphere
becomes dry and hard even to brittleness. For this reason

~s seldom used as a ceiiient alone where the surface of
contact ia small, us it would be apt to be displaced by any
sodden shock, especially when old. In the ordinary method
of naing, however, it serves the double purpose of preserring
the object and fixing the thin glass cover; whilst the com-
paratively large space npon which it lies lessens the risk of
displacement. By keppiog, this substance becomes thicker!
a very little warmth will render it liquid enough to use,
eren when to some extent this change has taken place.
When heated, however, for some time and allowed to cool, it
hecomes hardened to any degree, which may be readily
Kgnlated by the length of time it has been eipoaed, and

PJIEPAKATION iSD MOCNTISO

the Bmoant of heat to which it has been, subjected. Oa
aceouDt of this property it is oftea used with chloroform :
the bftleam ia exposed to heat until, on cooling, it assatneB
a, glaaay appearance. This will be most readily done by
baking it iu what we should call a " cool oven." Tho time
required will most likely be 20 or 30 lioura. Care muat be
taken that the heat ia not too great, elae the balsaoi will be
discoloured. It muat then be dissolved in pure cblorofonn
or benzole (the latter ia preferable) until it becomes of the
couustence of thick varnish. This liquid is very couvenieot
in some casea, as air-bnbbles are much more easily diapelled
than when nndilnted Canada balsam is used. It also dries
readily, aa the chloroform evaporates very quickly, for which
reason it must be preserved in a closely -stoppered bottle.
It baa been said that this mixture becomes cloudi/ with loQg
keeping, bnt I have not found it bo in any caaes where I
have used it. Cloudiness is most freqnently, if not alnkys,
caused by dampness in the object, as mentioned in Chapter
IT. Shoald it, however, become so, a little heat will gene-
rally dispel the opacity. The ordinary balsam, if exposed
mnch to the air whilst being used, becomes thicker, as baa
been already stated. It mity be reduced to the required
consistency with common turpentine; but I have often found
this in Bouie degree iojuriooB to the transparency of the
balsam, and the amalgamation of the two by no means
perfeol;. (See also Cbaptor IT.) Its cheapoesB renders it
no extravagance to use it always undiluted i and when pre-
served in a bottle with a hollow cover fitting tightly around
the neck, both surfaces being finely gronnd, it remains fit
for use much longer than in the ordinary jar, Canada bal-
sam may now be procured in collapsible tin tubes, like those
used by artists ; and its manipulation is thus rendered muoh
more easy, cleanly, and convenient, as well as economical.
Chloroform ia, however, frequently used for dilution, and is
perhaps the safest solvent we can employ.

Dauhak Taenish. — Some complain that thia varnish la
not easily procurable in a pure transparent statfi. It is
e^^ nsed by oar American friends in moantiug diatoms

ECT3. 45

and other fine work. It is very liquid, and ia tbougbt by
soma to be more easily worked than Canada balsam.
Dammar may be eaai]y dissolved in benzole to any extent.
Tiie lumps should previously be scraped nntil they are freed
from dnst and other impurities, and then rongbly crashed.

AspHALTUM. — This substance ia dissolved in linseed oil,
turpentine, or naphtha, and is oflen termed " Brunswick
black." It is easily worked, but is not generally deemed a.
Irtutworlhij cement, as after a time it is readily loosened
from its gronnd. It is, however, very useful for some pur-
poses (gneh as " finishing" the slides), as it dries quickly.
I shall, bowerer, mention a modidoation of this cement a
little farther on.

MiEINK Glue, — Uo cement ia more useful or trustworthy
for certain purposes than this. It is made in various pro-
portions; but one really good mixture is — equal parts of
india-rubber and gum shellac; these are dissolved in mineral
naphtha with heat. It is, however, mnoh better to get it
from the opticians or others who keep it. It requires heat
in the application, aa will be ouplained in Chapter V. ; hot
is soluble in few, if any of the liquids used by the microscopist,
&nd for that reason ia serviceable in the manufacture of
cells, Ac. Where two pieces of glass are to be firmly
cemented together, it is almost always employed ; and in all
glass troughs, plates with ledges, &c., the beginner may find
examples of its use.

Gold Size. — This substance may always be procured at
any coloarman's shop. The process of itii preparation is
long and tedious. It is therefore not necessary to describe
it here. Dr. Carpenter says that it is very durable, and
may be need with almost any preservativB liquids, aa it is
acted upon by very few of them, turpentine being its only
true solvent. If too thin, it may be exposed for awhile to
the open air, which by evaporation gradually thickens it.
Oare must he taken, however, not to render it too thick, as
it will then be useless. A small quantity should be kept on
hand, as it is much more adhesive when old.

GnH Dasimak Cejiekt.— An excellent cement may 1

46 PREPAEATIOX AND MOUNTIXO

made bj dissolving gum dammar in benzole, and adding
abont one-third of gold size : it dries very readily, and is
especially useful when mounting objects in fluid, taking care
that no moisture extends beyond the coYering glass, which
would prevent the complete adhesion of the cement. In
those cases where glycerine is employed as the mounting
medium, a ring of liquid glue put round the cover first, and
when that is dry, a second coat of gum dammar will keep
the cover very secure, and no leakage take place.

Liquid Glue is another of these cements, which is made
by dissolving gum shellac in naphtha in such quantity that
it may be of the required consistency. This cement appears
to me almost worthless in ordinary work, as its adherence
can never be relied upon ; but it is so often used and recom-
mended that an enumeration of cements might be .deemed
incomplete without it. Even when employed simply for
varnishing the outside of the glass covers, for appearance's
sake alone, it invariably chips. Where, however, oil is used
as a preservative liquid, it serves very well to attach the
thin glass ; but when this is accomplished, another varnish
less liable to chip must always be laid upon it, (See
Chapter Y.) Yet it makes excellent cells.

Black Japan. — This is prepared from oil of turpentine,
linseed oil, amber, gum anime, and asphalt. It is trouble-
some to make, and therefore it is much better to procure it
at the shops. It is a really good cement, and serves very
well to make shallow cells for liquids, as will be described in
Chapter IV. The finished cell should be exposed for a
short time to the heat of what Is usually termed a " cool
oven." This renders it very-tkirable, and many very cajreful
manipulators use it for their preparations.

Electeical Cement. — This will be found very good for
some purposes hereinafter described. To make it, melt
together —

5 parts of resin.
I „ beeswax.
1 „ red ochre.

OF mcBOsconc owecis, 47

It mnst be nsed whilst hot, and as long aa it retains even
slight warmth cSiTi be readily moulded into anj form. It is
often emplojed is making ahalloir cells for hqniJj, aa before
mentioned.

Grjt'WiTEB )B an article which nobody Bhould ever Uo
without; but labelp, or indeed any sobatanoe, affiled to
glass with common gam, are ao liable to leave it spon-
taneously, especially when kept very dry, that I base lately
added £ve or six drops of glycerine to an oance of the gam
Bolntion. This addition has rendered it very trustworthy
oven on glass, and now I never use it without. Ten grains
of moist sDgar to each oance of gum solution will also
answer eqnalty well. This solation cannot be kept long
without undergoing fermentation, to prevent which the
addition of a small quantity of any essential oil (as oi! of
cloves, &c.), or one-fourth of its volume of alcohol, may be
inade, which will not interfere in any way with its use.

There is what is sometimes termed an exlra adhesive
[fnm-water, which is made with the addition of isinglass,
thns : — Dissolve two drachms of isinglass in four ouaces of
distilled vinegar; add as mnch gnm arabic as will give it
the required consistency. This will keep very well, but is
apt to become thinner, when a little more gnm tnuy bo
added.

I may here mention that Messrs. Marion Imvo lately
broaght out a cement for the purpose of mounting photo-
graphs, which is very adhesive, eten to glass. I find it
naeful in all case? where certainty is requisite ; as gnmmed
paper ia liable in a dry piace to curl from tlie slides, as
*ieibre mentioned.

All these, eicept one or two, are liqoiil, and must be kept
n stoppered bottles, or, at least, as free from the action of
he air as possible.

When any two substances are to be nnifed Brmly, I have
termed the medium employed "a cement;" but often the
Eppearance of the slides is thought to bo improved by
Irawing a coloured ring npon them, eitending partly on the

48 PSEPiBATIOK iSD MOUNTIKO

cover and partly on the slide, liidlng the junction of tlie twa
The medium need in these casea I term a Tajikish, a
heroin urtcr mention one or two. Of course, the tenocitj ii
not required to be ao perfect as in the cements.

Sealing-'VVax Vaekisb is prepared by coarselj- powder
sealing-wax, and adding spirits of wine; it is then digested
at a gentle beat to the required tbicliness. This is Teif
fieqnentlj nsed to finish the elides, as before mentioned
and can easily be made of any colour by employing diSereot
liinda of aealing-wai; but ia very liable to chip
leave the glass. The best qualitiea, however, will be lesi

Black VA.E^"lSH — Is readily prepared by adding a amalt
quantity of lampblack to gold-size and mixing intimatelj.
Dr. Carpenter recommends this as a good finiahiug vamiBfa,
drying quickly and being free from that brittleneas whicli
renders some of the otliers almost worthless ; but it ahoold
not be used in the first process when mounting objects u
fluid.

Amongst these different cements and varnishea I worVed
a long time without coming to any decision as to thai
comparative qualities, though making innumerable erperij
ments. Tlio harder kinds were continually cracking, \
the Bofter possessed but little adhesive power. To fine
hardness and adhesiveness united was my object, aad the
following possesses these qualities in a great degree \—

India-mbber J drachm,

Aspbaltum 4 02.

Mineral naphtha 10 „

Dissolve the india-rubber in the naphtha, then ad
aspbaltum — if necessary, heat must be empluyod.

Some scientific friends have complained that they have
been unable to dissolve either the india-rubber c
aspbaltum in mineral naphtha. The frequency with whieli
I have seen this solution thoroughly accompHehed convince?

OF mcBoscopio OBJECTS. 49

me that one of tliese things baa occurred — either the india-

Fmbber or the aBpliHltom has not been pare, or the naphtha

' eon leoad iiiBtead of taineral. In the early photo-

rapiiio dajB everj artist made a form of this varnisK to

.ae with glass positives, and I never heard a complaint of

This ia often need bj photographers as a bla.cb Tarnish
IT glaas, and never crackii, nliilat it is very adbesive. Dr.
brpenter, however, states that his experieoce haa not been
tTODrable to it; bat I have used it in great qiiaatitiea and
lave never found it to leave the glass in a single inatance
rfaen used in the above proportions. The objections to it
re, however, I think easily explained, when it ia known
hat there are many kinds of pitch, &c., from coal, Bold by
he n&me of asphaltom, eome of which are worthksa iu
laking a microscopic cement. When used for this purpose,
he tiBphaltnm moat be genuine and of the best qaality
bat can he bought. The above niii:tare eervea a double
inrpose — to unite the cell to the slide, and aUo as a "finiah-
Dg " vamiah. But it is perhaps more convenient to have
fro bottles of this cement, one of which is thicker than
ommon varnish, to nso for uniting the cell, Ac.; the other
quid enough to flow readily, which may be employed ae a
NUrfaee varuiah in flniiihing the alides.

The brushes or camel-hair pencils ahonld always be
dwned after nse; hot with the asphalt varnish above
bentioned it is anffioient to wipe off aa carefully as posaible
2le snperflaous quantity which adheres to the pencil, aa,
irhen again nsed, the Tarnish will readily soften it; bot, of
tonrBe, it will be necessary to keep separate brashes for
jbertain purposes.

Here it may he observed that every ohject ahonld be
labelled with name and any other descriptive item as aoon
IB mounted. There are many little diflerences in the
nethods of doing this. Some write with a diamond upon
be slide itself; but this haa the disadvantage of being not
S eBBlly Been. For this reason a small piece of paper _is

50 PREPAKATIOD AND MOUNTINO

usaallj affixed to one end of the slide, on wbich is written
what is required. These labels may be bought of different
colours and designs ; bat the most simple are quite as good,
and very readily procured. Take a sheet of thin writing
paper and brush over one side a strong solution of gum,
with the addition of a few drops of glycerine, or grains of
moist sugar, as above recommended ; allow this to dry, and
then with a common gun-punch stamp out the circles,
which may be affixed to the slides by simply damping the
gummed surface, taking care to write the required name,
&o., upon it before damping it, or else allowing it to become
perfectly dry first.

There is one difficulty which a beginner often experiences
in sorting and mountiog certain specimens under the micro-
scope, viz., the inversion of the objects; and it is often
stated to be almost impossible to work without an erector.
Bat this difficulty soon vanishes, the young student becoming
used to working what at first seems in contradiction to his
sight.

Let it be understood, that in giving the description of
those articles which are usually esteemed necessary in the
various parts of microscopic manipulation, I do not mean to
say that without many of these no work of any value can
be done. There are, as all will allow, certain forms of
apparatus which aid the operator considerably; but the
cost may be too great for him. A little thought, however,
will frequently overcome this difficulty, by enabling him to
make, or get made, for himself, at a comparatively light
expense, something which will accomplish all he desires.
As an example of this, a friend of mine made what he terms
his " universal stand," to carry various condensers, &q, &c,,
in the following way : — Take a steel or brass wire, three-
sixteenths or one-quarter inch thick and six or eight inches
long ; *' tap " into a solid, or make rough and fasten with
melted lead into a hollow, ball. (The foot of a cabinet
or work-box answers the purpose very well.) In the centre
of a round piece of tough board, three inches in diameter,

tcrs. 11

snabe a hamiaplierieal cavity to fit balf of the ball, and bore
a hole through from the middle of tKia cavitj. to allow the
to paas. Take anoCher piecD of board, abont four inches
in diameter, ei'her roand or aquarp, and one and a half or
two inches thick, make a eioiilar cavitj in its centre to
a the other half of the ball, bat only bo deep as to
the ball to fit tightly when the two piecea of board
rewed together, nhich last operation mtiat be done with
or four BcrewB. Let the hole for the wire in the upper
part be made conical (baae opwards), and so large as ouly
to prevent the ball from escaping from ita socket, in order
that ibe shaft may move ahiut as freely as poaeiblo. Turn
cavity, or make holes, in the bottom of the Doder piece,
>d fill wiih lead to give weight ani eteadineaa. Thl?,
painted green bronze and varniahed, looks neat; and by
having piei^es of giilta-percha tabiag to fit the ahafl;, a great
Tftriety of apparatns may be attached to it.

Mr. Loy employs the following arrangement for diaseotinf;
insects or picking ont Poraminifera, &a. : he fits an upright
brass rod into a heavy leaden foot, this rod carries a hori-
Eonlal arm bearing at ita end a ring for holding a watch-
maker'a eye-glass; in foaussing it to hia work, he presses
the eye-glass down with his head, the weight of the ItaJen
foot^ keeping it in its place, and allowing it to follow hia
every movement.

Agaio, a " condenser " ia often required for the illomina-
tioD o( opaque objects. My ingenioua friend uses an
"engraver's bottle" (price 6d.), fills it with water, and
BDSpends it betwiiit the light and the object. Where the
lijjht ia very yellow, he tints the water with indigo, and ao
removes the objectionable colour.

I merely mention these as ciamplea of what may he
done by a little thoughtful contrivance, and to remove the
idea tbat nothing is of much valne eave that nhich ia the
work of profeasioDBl workmen, and consequently expensive.

52 PRSPARATIOK AND MOUKTIKO

CHAPTEB III.

TO P££PAB£ AND MOUNT OBJECTS **DBT.'

The term " dry" is used when the object to be moanted is
not immersed in any liquid or medium, but prefseryed in its
natural state, unless it requires deaniug and drying.

I have before stated that thorough cleaDlioess is necessary
in the mounting of all microscopic objects. I may bere add
that almost every kind of substance used by the microscopist
suffers from careless handling. Many leaves with fine hairs
are robbed of half their beauty, or the hairs, perhaps, forced
into totally different shapes and groups ; many insects lose
their scales, which constitute their chief value to the micro-
scopist ; even glass itself distinctly shows the marks of the
fingers if left uncleaned. Every object must alno be
thoroughly dry, otherwise dampness will arise and become
condensed in small drops upon tbe inner surface of the thin
glass cover. This defect is frequently met with in slides
wbich have been mounted quickly; the objects not being
thoroughly dry when enclosed in the cell. Many cheap
slides are thus rendered worthless. Even with every care
it is not possible to get rid of this annoyance occasionally.
A good plan is to fix the covers on to the cells temporarily
by dropping on two sides of them a composition of equal
parts of wax and resin : this allows of the easy removal of
the cover at any time, while the object thoroughly dries
and is protected from dust and damage.

For the purpose of mounting opaque objects " dry "
discs were at one time very commonly used. These are
circular pieces of cork, leather, or other soft substance, from
one*quarter to half an inch in diameter, blackened with varnish

or HicaoscoFic ouects. £3

or cavcred with black paper, on whiob the abject is &xt<i bj
gnm or eome other adbrsive Babstance. Tbej are oauallj

]iiereed loDgituJinally b; a strong pin, which aervea for the
forcepa to laj hiiid of when being plaoed under the micro-
scope for examination. Sometimea objects are affixed to
both Bides of the diso, nhich ia readilj tnined vhcn under
the objtfct- glass. The advantage of Ihia method of mount-
ing ia the ea^e with nhich the disc ma; be moved, au>I so
preeent every part of the object to the eye, fflive that by
which it ia fastened to the disc. On this account it is ot^en
used when some particular subject is undergoing iinestigft-
tioQ, aa a number of specimens may bo pWcd upon the
discs with very little labour, displayiog all tlieir parte. But
where eiposnre to the atmosphere or small partiuica of duat
will injure an object, no advantage nlitch dmcs may possess
should he considered, and an ordinary covered cell ahonld
be employed. Small pili-boxea have been used, to the l>ot-
torn of nhich a piece of cork haa been glued to alTord a
ground For the pin or other aiaSe of attachment ; but this
ia liable to scim« of the aame faults aa the diac, and it would
be nnwiae to use these for permanent objects.

Ueaara. Smith and BkcIi have lately invented, und are
noir making a beautiful small apparataa. by means of
which the diac supporting- the object can be worked with
little or no trouble into any position that may prove moat
ooQTenient, whilst a perforated cylinder aerves for the ri:cup-
tioB of the diaca when ont of uae, and fits into a oa«e tO
protect them from dust. A pair of forceps ia made for the
express purpoae of removing them from the onsa and placing
tliem in the holder.

All dry objects, however, which are to be preserved should
1m moauted on glass slides in one of the cella (described in
Chapter II.) best suited to them. Where the object is to be
free from pressure, care must be taken that the cell is deep
enoogh to enaure this. When tbe depth required is but
■mall, it ia often sufGciont to omit the card, leulher, or
oth«r circlea, and with the " turntable " before described by

t>4 FREPARATION AND MOUNTING

means of a thick varnisli and camel-liair pencil, to form a
ring of the desired depth ; bat should the yarnish not be of
sufficient substance to give such *' walls " at onne, the first
application may be allowed to dry, and a second made upon
it. A number of these may be prepared at the same time,
and laid by for use. When liquids are used (see Chapter V.),
Dr. Carpenter recommends gold-size as a good varnish
for the purpose, and this may be used in dry mountings
also. I have used the asphaltum and india-rubber (men-
tioned in Chapter IL), and found it to be everything I could
wish. The cells, however, must be thoroughly dt-y, and when
they will bear the heat they should be baked for an hour at
least in a tolerably cool oven, by which treatment the latter
becomes an excellent medium. All dry objects which will
not bear pressure roust be firmly fastened to the slide,
otherwise the necessary movements often injure them,
by destroying the fine hairs, &c. For this purpose thin
varnishes are often used, and will serve well enough for
large objects, but many smaller ones are lost by adopting
this plan, as for a time, which may be deemed long enongh
to harden the varnish, they exhibit no defect, but in a while
a ** wall " of the plastic gam gathers around them, which
refracts the light, and thus leads the student to false
conclusions. In all finer work, where it is necessary to
use any method of fixing them to the slide, a solution of
common gum, with the addition of a few drops of glycerine
(Chapter II.), will be found to serve the purpose perfectly.
It must, however, be carefully filtered through blotting-
paper, otherwise the minute particles in the solution interfere
with the object, giving the slide a dusty appearance when
under the microscope.

When mounting an object in any of these cells, the glass
mnst be thoroughly cleaned, which may be done with a
cambric handkerchief, after the washing mentioned in Chap-
ter II. If the object he large, the point of a fine camel-hair
pencil should be dipped into the gum solution, and a minute
quantity of the liquid deposited in the cell where the object

OF MICROSCOPIC OWECTS. 55

be plaaed, but not to cover a greater surface tbaa the
object will totally hide from eight. This drop of gum must
be allowed to dry, irbi^h will take a few minutes. Breatlie
then upon it two or tbree timea, holding the elide not far
from the month, which will render the surface adheBive.
Then draw a, camel-hair pencil throutjb the Hpa, bo aa to
moistea it Blightly (when anything small will adhere to
it quite firmly enoagh), tonch the object and place it
npoQ the gum ia the desired position. This must be dona
immedialely to ensure perfect stability, oilierwiae the gnm
will become at least partially dry and only retain the object
imperfectly.

When, however, the olijects are bo minnfe that it would
! be impossible to deposit atoms of gum amall enongh for
each one to cover, a. different method of proceeding must be
adopted. In this case a BmuU portion of Iba same gum
solution ahonld be placed npon the slide, and by means of
any email inatvoment — a long needle will serve the parpoae
Tery well — spread over the surface which will be required.
The quantity thus extended will be very small, but by
treatbing npon it may be prevented drying whilst being
dispersed. This, like the forementinoed, should be then
I allowed to dry; and whilat the olijects are being placed on
the prepared surface, breathiog upua it as before will restore
the power of adherence. A small patch of gold-si^.e — -or
gam dammar aolution which has been allowed to became
"taekey" — la very uaeful in many caaes.

When gum or other liquid cement baa been used to fis
the objects to the glass, the tbio coverfl must not be applied
until the slide has been thvTOugldy dried, and all fear of
dampness arising from the use of the solation done away
with. Warmth may be safely applied for the purpose, aa
olgeots fastened by this method are seldom, if ever found to
be loosened by it. As objects are rnet with of every tbicli-
nesa, the cells will be requirnd of different depths. There
18 no difficulty in accommodating oursdves in this — the
deeper cells may bo readily cut out of thick leather, card, or

56 FREPABATION AHD MOXTNTDTG

other snbstance preferred (as mentioned in Chapter II.)*
Cardboard is easily procured of almost any thickness ; bat
sometimes it is convenient to find a thinner substance even
than this. When thin glass is laid upon a drop of any
liquid npon a slide, every one mast have observed how
readily the liqaid spreads betwixt the two : jnEt so when
any thin varnish is nsed to snrroand an object of little snb-
stance, excessive care is needed lest the varnish shonld
extend betwixt the cover and slide, and so render it worth-
less. The slightest wall, however, prevents this from taking
place, so that a ring of common paper may be used, and
serve a double purpose where the objects require no deeper
cell than this forms.

Many objects, however, are of such tenuity — as the leaves
of many mossep, some of the DiatomacesB, scales of insects,
&o. — that no cell is requisite excepting that which is neces-
sarily formed by the medium used to attach the thin glass
cover to the slide ; and where the slide is covered by the
ornamental papers mentioned in Chapter IL, and pressure
does not injure the object, even this is omitted, the thin
glass being kept in position by the, cover ; but slides mounted
in this manner are frequently injured by dampness, which
soon condeoses upon the inner surfaces and interferes both
with the object and the clearness of its appearance.

The thin glass, then, is to be united to the slide, so as to
form a perfect protection from dust, dampness, or other
injurious matter, and yet allow a thoroughly distinct view
of the object. This is to be done by applying to the glass
slide round the object some adhesive snbstance, and with the
forceps placing the thin glass cover (quite dry and clean)
upon it. A gentle pressure round the edge will then
ensure a perfect adhesion, and with ordinary care there will
be little or no danger of breakage. For this purpose gold-
size is frequently used. The asphalt and india-rubber
varnish also will be found both durable and serviceable.
Whatever cement may be used, it is well to allow it to
become in some measure fixed and dried; but where no

or MICKOSCOEIC OBJECTS. 57

■ wall ia npon the elidp, this ia quUe neeegsaiy,
otherwise the varniah will be mnst certain to estend, as
before mentioDed, and rata the object. It may be stated
I that gold-size diffdra greatl; in ita drring powers,
Bccordiug to ita age, mode of preparation, &::, (Chapter Y.) :
liere gum dammar Rolntioii laid od ia a verj thin coating
will be foond moat n^erul, aa it dries so rapidlj ibat it caauot
an in Dnless laid on nilh an nufiparicg band.

Shonid any object be encloaed nbich reqairea to be lept
fiat dariog tbe drying of the cement, it wilt be ueceiiaarj to
e of tbe contriTances mentioned iu Chapter 11.
1 tbe slide is thas far advanced, there remains the
finiahing only. Should tbe atuJenf, however, have no
time to complete bia work at once, be may saMy leave it at
this stage nntil he have a number of slides which be may
fiaisU at the same time. There are ditferent methods of
> doing thia, some of nhich may he here described.

If ornamental papers are preferred, a small circle mnat
be cut ant from the centre a little lens that) the thin glass
which covera the object. Another piece of coloured paper
18 made of tbe same size, and a similar circle taken from ita
centre alao, or both may be cut at the same time. The
, ilide ia then covered roond tbe edges with paper of any
pluD coloor, BO that it may extend about one-eigbtb of an
inch over the glass on every side. Tbe ornamental paper
ia then posted on tbe " object " sarfaee of the glaaa, so that
the circle shows the object aa nearly in tbe centre as ponaible,
and covers tbe edt;ea of the thin glass. Tbe other coloured
paper ia then a£ied nnderneath with the circle coinciding
■with that above. And here I may observe, that when this
method ia need there is no necessity for the edges of the
■lide to be groond, as all danger of scratching, &c., is
obiritttcd by the paper cover.

Many now nse paper oovers, abont one and a half inch
long, on the upper side of the slide only, with the centre
cat out aa before, with no other pnrpoue than that of
hiding the edge of tbe thin glass where it is united to the elide.

58 PHEPAJtiTlOS iKD MOTINTISO

The melbod of fi.aifili!ti^, however, trhich ia moatlj used
6.i the [ireaetit time, ie to laj a coating of varnish upoa tha
edge of the Ihin glaaa, and extend it some little way on the
alide. When a black circle ia reqaired, nothinff acrves the
purpose bett«r than the goU-siza and lampblack, or tiifl
BBpbalt and inditi-rubber TartiiHh, neither of which ia liabla
to chip; but nhen uaed for thia. the lutler aboald be rather
thinner, aa bsrore adviaed. Soriie of these varaishea ara
preferred of different colonra, which loaj be mai'e by using
the different kiniia of aeHliu[{-wai, aa described in Chapter II.;
but they are alnaja liable to the dufucts th-re meutiooed.
' Tbia oiruls cannot be mude in any other nay than by one of
thoae coatrivancea called torntablea. A very litde praotioe
wilt enable the young student to place his slide eo that tlia
circle may be nuiform with the edge of the thin glaaa.

The alide ia now conipletp, except the addition of tlie
name and any oiher partlculHra which may be desirable.
For this purpose one of the methoda deacribed in Chapter XL
must be employed.

Amongst the various claaseB of microscopic objects noir
receiciog general attention, the DlatomacPSB may ha plooed
in a prominent position. They afford endlesB opportnnitiM
of rcBearch, and some very eldborate worta have already
been isHoed concerning them. Professor Smith's may lie
mcntion<;d as one aontaioing, perhaps, the beet illustratioiia.
The yniing atadent may wish to know what a diatom ia.
The ''Micrograpbic Diclionarj" gives the foUowiog defi-
nition; — "A family of confervoid AlgEB, of very pecnliu
character, eonsistio^ of microscopic brittle organlBOiB."
They are now looked upon by almont all of our acientifie
men as belonging to the vegetable kingdom, though some
few still af'Hign them to the animal. They are almost
invariably bo exceedingly email, that the anaided eys oan
perctivB nothing on a prepared slide of these orgaoisma but
minute dnst. Each srparate portiou, which ia usoally seen.
when mounted, is termed a "frustule," or " tectiile :" this
consista of two bimilar p&rta, composed of silica, between and

OF MtCKOSCOnC OBJECTS. 53

BOmetimea around whieh, is a mass of vistid matter ailed
the " eadochrome." Thej are found in almost every doaerip-
tion of water, according to the varietj; some prefer Bfla-
vater, others fruah, and manj are eeen nowhere liut !□ tbat
vhich is a mistiire of both, as the luocths of rivers, &e.
Ditches, ponds, cisterns, and indeed almost everj reservoir,
jfield ahoodance of these forms. They are not, however,
confined to "present" life; bat, owing to the almost in-
deetructible nature of their eilJceoua coveriog, they are
found in a fossil atate in certain earths in great abundance,
and are often termed " fossil Infasoria," Upon these frua-
tnles are generally to be aeea lines, or markings, of
different degrees of minuteness, the delicacy of which often.
BBrvea the purpose of testing the deBning power of object-
glasses. Some of the frustules arc triangular, others circular,
and, indeed, of almost every conceivable shape, many of
them presenting us with exquisitely beautiful designs.

Tbe markings, however, are seldom seen well, if at all,
until the frustulea are properly prepared, the differeot
methods of accomplishing which will be givea a little
farther on.

The collection of fresh diatoms is so closely connected
with, their preservation, that a few notes may be given opoii
it. before vie pass on. For this purpose a number of small
bottles mnst be provided, which may be placed in a tin box,
with a separate compartment for each, so that all chance of
lireakage may be done away with. The diatoms are generally
of B. light brown colour; and where they are observed in the
water, the bottle may be so plated, with the moulh closed
by the finger, that when the finger is withdrawn the wat«r
will rush in, carrying the diatoms also. If thej are seen
upon plants, stones, or any other substance, they may
generally be detached and placed in the bottle. When
there is a green covering npon the surface of the water, a
great quantity of diatoms is usually found amongst it; as
also npon the surface of tbe mud in those ponds where they
abound. In these cases, a broad fiat spoon will be found

CO rnEPiHiTiON *SD siocnting

yery nBefnl, and one U now made with a wiTeriog npon Iha
liroader portioa of it to protect the eoclosed matter from
Wag BO readily carried dIF whilst bringing it to the s-
again. Where there ia any depth of nater, and the spoon
will not reach the sarface of the mud, the bottle must be.
united to a long rod, and being then carried through Ihs
upper portion with the oiouth downwards, no water will bc
received into it; bat on reaching the spot required, :'
bottle-mouth may be tnrned ap, and thus become tilled witll
what IB nearest.

Prom tbe storaacba of common fish — as the cod, eole, hadf
docb, &a. — many specimens of Diatomaccaj may be obtained
but eepecially frnm the crab, oyster, mussel, and other si
fish. Professor Smith states that from these cnrii
tacles be hail taken some with which he has not elaewha
met. To remove them from any of the small shell-fish, it i
neoesaary to take the fish or stomach from the shall, m
immerse it in strong hot auid (nitric is the beat) until tl
animal matter is disBolTed, when tbe residue mnst
washed and treated as the ordinary Diatomaccco hereinafbi
described.

Many diatoms are Been best when mounted
state, the raiuute markings becoming moch more indistioi
if immersed io liquid or balsam; and for this reason th
which are used as teat objects are nsnally mounted o
Many kinds are also now prepared in this way aa opaqi
objects, to be examined with the lieberknhn, and ara ■
quisitely beantiful. Others, however, are almost invarial
mounted in balsam ; but as these will be again referred I
in Chapter IV., and require the same treatment to fit the)
for the slide, it will not be out of place to describe t'
cleaning aad preparation of them here. As before stati
there is miich matter surrounding them which mast 1
got rid of before the iiliceous covering caa be show
perfectly. As, however, we may first wish to becon
acquainted in some degree with what we have to do, it :
well to take a small piece of talc, and pluce a few of th

or MiCBoscoric objects. ^1

o it. TliiB may be teld over the flwno of Ui«

■^rit-lamp until mil tie snrroandicg matter is hnrnt avay,
aitd A tolerable idea may Uiub be obUuned as to tliii iiuditjr
r treasore.

Mm« cases it ia well to ttse tbis barnioff 0|)«ration

■lone in mcunting specimens of diatoms, when thej luaj bo
placed in tbeir natural state upon thin glass, burnt for
airhile upon the platinam plate, heretnaftei' d<iscrib«tl, and
motinted dry or in balsam.

In the preparation and cleaning of Diatoniaoew, tlioro js
little satisfaction unless these operatiooa bavo boon suooras-
fttUy performed, as a very email portion of foreign matter
serionely interferes with the object. The mode of proparinK
them varies even amongst the most experienced. It will ho
fbnnd, therefore, moat Batisfaotory to examine tho prinolpal
of these separately, although it may be at the risk of sumo
little repetition.

The method which ia moet freqnontly employed is the
following; — Place the gntheriog oontaiiiiiig the Dinto-
macece in a small glues or porcelain Teenol, add strong
nitric acid, and, by the aid of a Bunaen's burner or spirit'
lamp, boil for some minuteH. From time to time a drop of
the mixture may be put open ii slide, and examined uiidor
the microscope to see if all foreign matter bo got rid of,
When the ralves are clean, the vessel contuiuing thpm must
be filled with water, and the whole left fur an hour or two,
BO that all the diatoms may boIUb perfectly. Tho liquid
mnst then be poored off carefully, or drained away by the
■jd of a Bj-pbon, so that none of the diatoms are ramovod
with it. Indeed, it is well to examine the liquid drsined oft
each time with the microsccpo, as tho finer forma aro
frequeutly lost in the washings. The vei^sol most th*n be
refilled with pure water, allowed to settle, and drained aa
before. This washing must bo repeated until a drop befng
placed opon a slide and evaporated leaviai no etjmUU,
When it is desirable to preserve the diat/jms in thia atat*
Woie moantiog (which proceai will be described in aootJ

plact'), they maj be placed in a amall phial with a litthl
diatilled water.

There are many caaea in whiah the shore method will n
eOect a perfect cleaDsing, as certain gnhatances with whl
diatoiDs are frtiqaently mixed are not soluble in nttrti: ne\
For thia reaflOD the following method ia reenrted to :— Ta
a qaantitj of the matter containiiig the Diatomaceis ana
wash first with pare water, to get rid of all the impnritid
poaaible. Allow this to sellle perfectly and decant tba
■water. Add hjdrochlorio aoid gradually, and when alt
eServeaccnce has sobsided, boil for aome minDtcs hy aid oi
the lamp. Wben cool and the particles have sabBtdecl
decant the hydrochloric and add nitric acid. Tbe boilinj
mnat then be repeated until a drop of the liquid whet
placed nnder the microscope shows the tbItus or " frnatnleH'
clean. After allowing tbe diatoma to settle, the aoid n
he decanted, and pure water anbatituted. Tbe waahinj
mnat he repeated aa in the former proceaa until all t
lemains of crystals or acid arc removed, when tbe apecimenj
may be preserved in amall phials.

Snch are the nenal modea of treating the Diatomacefla
hut there are certain cases in which particular methods ar
required to give anything like perfect naults. Persons a
great experience combine a variety of treatmenta, and thw
obtain better and more nniform apecimens. Perhaps it wil
he advantageous to give the yonng atudent the proces
adopted by one of the moat saoceBsfol preparers of f
objeota ; but I will Brat state the different methods a
mounting the cleaned diatoms dry : how to employ Canadt
balsam and fiuid in their preaervation will be elsewhert
described.

It was before stated that diatoms when cleansed migh
be preserved in small pbials of distilled water. When
quired for monnttng, shake the phial, and with athin glaa
tube or rod take op a drop of the Suid and Bpread it npol
the snrfnce of the alide in tbe desired position. Thii
then be allowed to dry gradually, or by the aid of tbe lsin|

itiioat being shaken or iaterrered with, otlier-
wise Dniformity of dispersioo will be prpveoteii. When
titorougMy d'j, a thin ring of one of the adhenife varnirhea
' — gold-^ise will be round as good as ao; — 'oaj "be druwn
ronnd the djatomR, and allowtd to drj in a slight degree.
The slide and tbio glass cover should then be warmed and
the latter gentlj pressed opon the riog of TarQisb aotil iha
BdhesioD all round is cotDplet«.

As some of the diatoms require object- glasses of eitremely
high power, and cnaeqDeDtlj short focos, to show them,
they mnst be an close to the onter sarfaee of the cover aa
possible. For this reasoD thej are BOmetimes placed upon
the nnder side of the thio glass, aa follows. Clean the
BQifacee of the elide and cover, and with the rod or pipe
place the liqnid containing the diatoms upoo the thio g'ass,
and dry as beFore. Trace the ring to receive the cover upon
the slide, and when almost dry. warm both and proceed as
■.bove. Whichever of these methods is employed, the outer
ring of coloured varnidh may be applied as elsewhere descrilwd
and the slide finished.

Diatoms are also sometimes mounted betwist two thin
glasses, as deacribed in Chapter II.. so that the light by
vhiah they are examined njay receive as little interference as
poaMble, and that an achromatic condenser may be brooght
into focns under the slide.

Of the various modes of cleaning and moanting Dinto-
niacero, I believe that the following may be safely recom-
. mended, as affording results of the bent quality. My friend,
I Mr. T. O, Bylands, gave it to me as that which he prefers,
and I can salcly say that his numerous slides are at least
equal to any I have ever aeen. I will give it just aa I
received it from him, though there may be some little
repetition of what has been said elsewhere, hb he does not
appropriate any part of it as his own. He says ; — In this
branch of mountini;, general rules alone can be laid down,
because the gatherings may contain iron, lime, fine silt, or
vegetable matter under conditione for special treatment, and

I ;

ft

cotiaeqacntlj the first step shonld ba to experiment on

Id leathering diatomE raDch laLonr is saved by jndgmeBl
and care; hence il is desirable to get acqnaiuted with then
in their growiD^ conditioD, ao that when recognised npa
the sand or otber spotfl, thej maj be carefnllj remavecl fa
the aid of the spoon or small tin scoop before deaoribet
When growing upon algiB or other plants, the plante ui
diatoms together ma; ha carried home, in nhich case thi^
mntit be simplj drained and not nashed or pressed, in ordfl
that the diatomn be not lost. As it is atwajs desirable t
examine the gathering on the gronnd, a " Gulrdner's hftm
micro B cop e " with powers from 80 to 200 diameters will b
fonnd very useful. The beat gatherings are those whid
represent one species abundantlj. Those which are nixei
maj be rfjected, unless they are seen to contain somethiog
falaahle or important, as the object shonld be not so mnci)
loBopply microBCopical curiosities as to collect material whioh
is availsbte for the study of nature.

The gathering when carried home should always he (i
fnlly Biamined before anything ia done with it ; not only oft
account of the additional information thns acqnired, bnl
also because it often happens that a specimen sboiild b
mounted in Quid (see Chapter Y.) in the condition in whiol
it is gathered, as well as cleaned and mounted in ball
(Cbspter IV.) and dry.

Where the gathering ia taken from sand, the whole it
be shaken up in water as a preliminary operation, whel
much of the sand will be separated bj its own weight. Thi
lime test, however, should be applied; viz. — a small pottim
of hydrochloric acid, aod if there be effervescence, it most bl
dissolved out by this means. From Algie and other wee
diatoms may be detached by agitating the whole t«getfa«
wealc solution of nitris acid — about one of pare acid to
twenty or thirty of water, as it must be sufSciently weak to
free the diatoms without destroying the matter to which
they adhere. The diatoms may then be separated by

ECTS. 65

Bifting thtOQgh coarae muslin, which will retain the Algm,
&a. The prOBesa of cleaning will vary aocordiog to circom-
BtaooeB. Some gatherings rec[iiire to be boiled only a few
mittuteB Id nitric acid; but tiie more general plan, where
they are nixed with organic or other foreign matter, is to
hoil them in pare salphurio acid until they cease to grow
darter in colonr (usually from a half to one minate), and then
to add, drop by drop to avoid eiplosioaa, a cold saturated
Bolntion of chlorate of potaah nntil the colouris disobftrgea,
or, in cose the colour does not disappear, the quantity of
the Bolntion need is at least eqaal to that of the acid.
This operation is beet performed in a wide-mouthed ordinary
beaker glass,* a test-tube being too narrow. The mixture
whilst boiling should be poured into thirty times its bulk of
cold water, and tho whole allowed to subside. The fluid
most then be carefully decanted and the vessel re-Buppli«d
once or twice with pure water, ao as to get rid of all the
acid. The gathering may then he transferred to a smalt
boiiing-glass or test-tube, and — the water being carefully
decanted — boiled iu the a mall est available quantity of
nitric acid, and washed aa berore. Thia laat process has
been found necessary from the frequent appearance of
niinote crystals, which cannot otherwise be readily dis-
posed of without the loss of a considerable proportion of
diatoms.

I may here mention that the washing-glaaaes used by
Mr, Rjlanda are stoppered conical bottles varying in
capacity from two ounces to one quart; the conical form
being employed to prevent the adherence of anything to the
side ; they are stoppered, to render them available in the
shaking process about to be described.

The gathering, freed from acid, is now put into two inches
depth of water, shaken vigorously for a minute or two, and
allowed to subside for half an hour, after which the tuibiJ

* Ttieia glBEaee are round, atiDut six inches high, and usnally contain
about eight ounces. Tlis; are rather wider at the bettuui, tapering
gradually to t^ top, and may be generally procured at the chemists, do.

*

66 PBEPAEATION AND KOrSTING

fluid iniiat be care fullj decanted. This operation mnet Iw
repeated until all the matter is removed nhicli will not
settle in half an honr. The fluid removed ehoold be ei*
amined by a drop being put upon a slide, aa in some
very light diutoma have been found to come off almoat
pare in one or more of these earlier waibings. The quan-
tity of water and time of sabsideuce giveu may be taken
generally, but may reqaire to be modified according to
rircumstances and the judgment of the operator. By th»
repetition and variation of this proceBS — the akakiny hwtgi
the moat important part — the gathering, if a pwre one, will
ifficientlj clean. If, however, it contain a variety <^
ipeciea and forma, it may reqnire to be divided into differerd
den fU if a.

le oases, however, it ia beat to divide the gathering
as A preUminary operation, which may be done by s^tating

in a qnantity of water and decanting what does i
readily anbaide. The heavier and the lighter portions ara
then to be treated as two aeparate boilings. Bat when tb^
cleansing has been carried to the above stage and thit
division ie required, the plan most be somenbat as follows : —
The gathering mnst be Bhalen in a test-tvbe with six inohOI
of water, and then allowed to eubside until one iach at the
top remains pure. About three inchca are then to be care-
fnlly withdrawn by a pipette, when the tube may be fillrft
up and the operation repeated. The three lower inches e^»
may then be decanted and examined. Tbe gathering i
thus divided into three portions; viz. — that which w»
withdrawn by the pipette, that which remained floating
in the lower three inches of water in the tnbe, and!
that which bad settled at the bottom. An examination of:
these will inform tbe operator how to obtain that partienlar
density of gathering which he desires, and how far it il
wQrtk while to refine thia procesa of elutriatiau ; li
cases of neuesRity any one, or all three, of these densititt
may be operated upou in the same way to separate b
particular diatom.

0? Micaojcopic OBJXCTS. 67

Aa an occasional aid, it may be remarked, tliat io some
casea liquor ammoiii^e may be nsed io one of tlte later
^aahinga in place of water, aa it often Beparatea fine dirt,
-wbtcli is not otberwiBe easily removed. Ammonia aleo dis-
solves R BoccnUot matter whicb iometimea remains ; and
tbia method does not injure diat«tas like some «troDg alkalies.
Some foasil deposits require to be treated with a boiling
eolntion of carbonate of soda to disintegrate them ; bat
this operation reqnirea great care, lest the alkali ahontd
deatroy the diatoms. Yegetable ailicatcs also sometimes
require to be removed by a aolotion of carbonate of soda;
bnt as the frnstulea of the diatoms themaelvea are bnt
vegetable silka, even more care is required ia tbia case. It
may be well to mention, that some diatoms are so imperfectly
ailiceons that they will not bear boiling in acid at all. Soma
of tbese may be allowed to stand in cold nitric acid some
time, whilst others of a smaller and more delicate character
should, when possibie, bo treated with distilled water

We will now consider the mode of monnting the prepared
diatoms, which, if nsed dry (aa described in this chapter),
Bhonld be carefolly washed two or three tlmea with the
pnrest distilled water. In this branch, as in ever; other,
each collector gives preference to that method in which he
is an adept. Thus the diatoms may be placed on the
nnder side of the cover, to be as near to the object-gUas
as possible, or npon the slide itself; and each plan has
its adrocates. Whichsoever of these is nsed, nothing seems
more simple to the novice than a. tolerably equal dispersion
of the objecta opou the slide or cover ; but this is by no
means ao readily accomplished; coDEcqnently I give Mr.
Bylands' method, as his slides are perfect in thia respect
also. He always places the diatoms upon the thin glass
cover. It is not sufficient, aa is freqnently thought, to
take a drop of liquid containing the cleansed material and
spread it npon the cover or slide, as without some additional
precaution that uniform and regular distribution of the

63 FBEF^XA.Tios AXD liovsTisa

specimens, which ia deiirablp, 19 not obtaioed. In order to
effect this, let a drop of the cleanced gathering be dilnt«d
lufficifotlj for the porpose — hot* macb must be deteriniiied
in each ease bj experiment — and let the covers to ba
Tnoanted be cle&ued and liud upon the brass plate. (9f
Chapter IL) By means of a glass tube, abont one-twelfth of
an. inch in diameter, stopped by the wetted finger at ths
upper end, take np as mnch of the dilated material as wiQ
form a moderately conres drop eitending over the whole
cover. When all the coverB required are thaa prepared,
apply a lamp belotr the brass plate, and raiee the tent'
peratnre to a point jnst short of boiling. By this meant
the covers will be dried in a few minutes, and the specimena
eqoally distributed over the whole area. The spread of'
the Said npon the covers is facilitated by breathing npoa
them ; and, to insure oniformity, care mnst be takea to
avoid shaking them whilst drying. The beat pit
mount at least half a dozen at once.

Before mounting, Mr. Aylands always bums the diatom^
npon the glass at a dull red fae.at, whether they are nsej
with balsam or dry. This burning, he saya, is not only
an additional cleaning process, bnt it effectually fixee the
diatoms, and prevents them floating out if moanted mtll
balBam. The thinnest covers may be bnrnt without damag
if they are placed npon a small piece of platinam foil (
the size required, which should be about one-hundredth (
an inch thicb, perfectly flat, and having three of its edge*
slightly bent over, so ae to prevent its warping with th^
heat. The graall flame of a spirit-lamp, or, where ther" '""
gas, a Bunsen'R burner, may be employed. The 1
should be shaded from direct daylight, that the action t
the flame may be obaerved more perfectly. Care must then
be taken to raise the temperature only to the dull red heat
before mentioned. The cover will then be in a fit state fl
moan ting as required.

It has been stated in another place that it is assnoied
that the operator is not mounting diatoms simply aa □

n t4

or siicBOsconc objects. C9

e«pic objects, bat as iustractive Fpecimecs. It i« not,
lltirref<are, enfficient to lai'e a EiGgle elide as all tJiat is
reqnired, but to bave tbe sajne diatom prepaied in as manj
ways BH poMible. Tbe following are tbe principal: —

1. Itoanted crude in fluid (see Chapter T.)

2. Burnt cmde apon tbe cover, and muncled drj or in

3. Mounted drj or in balsam (see Chapter IV.), after

the cleansing prooesa alreadj described.

I will brre give Mr. fijianda' method of mounting tbem
{try, the Said and balaam preparations being noticed in
Iheir respective chapters. Tbe slide, with the ring of
asphalt, or black TaraiEh, should bave been prepared soma
weeks previously, in order to allow it to dry thoroughly.
When required, it must be held over tbe spirh-lamp or
SuDsen's burner until the ring of varniab is softened. The
bamt cover, having been heated at tbe same time, must
then be taken in tbe forcepa and pressed upon the softened
vamiBb DDtil it adhere all round. When cold, an outer
ring of asphalt completes the elide.

Saob is tbe method which my friend Mr. T. G. RyUnda
employs in the preparation of diatoms for the microscope.
I bave said enough concerning his resnlts. It is to be
feared, however, that to some these several modes of opera-
tion may appear lengthy and complicated ; but if read
carefully, and the experiments tried, they will be found to
be simple enough in practice, and to occupy much less time
than an intelligible description would lead the novice to
believe necessary.

The minute nature of diatom forms, and tbe high micros-
copic powers by which they are eiamiuad, render a very
shallow cell necessary when they arc mounted upon a dry
slide. Many early atitempts, on this account, have been
ruined by tbe cement used to fix the thin cover tiproading
underneath. A correspondent of the " Monthly MicroBOopio
Journal " thus gives his mode of avoiding this : — " There it
a very simple means of avoiding this danger, and I will

70

now deecribi) it. A oirele of bituman about one third
Bmaller than the coveriog glasa ia drawn befarehai
slides. When I wish to maka a preparailioo, instead c
GoattDg, a9 formerly, the first circle with a aecotid lajer
bitniueo, I form a aecood circle of it ootside the first, and
as Dear as posaihle to it, and each of the two cirolea has its
own advantage ; the first, in fact, while forming the celli
eei'res as a support for the covering glass, and thna prft<'
serves the Diatomaceffi from anj breakage ; it offers, hesideB,
a aeriotia obstacle to the epreaditsg of the tnore liquid bitn-
men of which the oater circle is oorapoaed ; and the li
closes the cell by fixing the cover, which, when the prepara^
tion is drj, may be covered with a fioal circle of bitnmenl
lb is of course understood that I am speaking of prepaid
tiooa made in the drj way onlj, and Dot <vith halsam."

One of the most fertile as well as the most curioua maga^
zioes of DiatoraaceiB is guano. The siliceona forma i
taioed tfaerein have been devoared bj sea-birds a
through the stomach aninjared, and after Ijiog for
may be cleaned and classified. Many of these ere not e]se<
where met with, so that the student who ia deairooa to entel
into the study of DJatomaceio must be instructed as to the
best mode of obtaining them from thia sonrce. The parr
ticnlars to be observed ao closely resemble those before n
tloned in the treatment of the ordinary diatoms, that it n
be sofficiently explicit to give the ontlines of the procesK
The guano must be first washed in pure water, allowed t"^^
subside perfectly, and the liq^uid then poured off. Thi
must be repeated until the top Qaid is clear, and care takeii
not to decant the Hqaid until perfect subsidence haa takeq
plaoB. Tlie deposit must then be treated with hydrooblorii
acid with a gentle beat for an hour or two, adding a little
fresh acid at intervals as long as it excites any effervescencei
After thia tjitrio acid must be aabatituted for the hydro-
ohloiie, and the heat kept up to almost boiling-point fo(
another hour at least, adding a little fresh acid as beforai
When thia ceasca to act, the deposit mnat be allowed t

OF Micaoscopic OBJECTS. "1

settle perfectly and the acid poured off. All traces of the
acid must now be washed away witii pure water, wian the
remaias will be Diatomace;:e, the sand cod tain ed in the
gnano, and a few other forma. Some of these may he
moanted dry, as before meotioned, hat the greater portion
ahonld he put up in Canada balsam aa described in
Chapter rV.

Such is the ordinary method for the treatment of guano ;
but Mr, Ejlanda' mode of proceeding with ordinary Diato-
macem (before given) nill be found equally suocessful with
theae deposits.

The compoaition, however, of guano is more complei than
the Bobstances by which we Sod most of the Diatomaccie
surrounded, and therefore a, different method of treatment
is puraned by many. The following by Mr. A, J. Eoberta
is B good one : " Guano should be first well washed with
Ijoiling water, either on a paper filter or by repeated affu-
BioDH until the liquid come off tasteless. Boiling water is
preferable to cold, for the heat espels air-bubbles and causes
the deposit to settle down into a smaller space; then the
deposit mast be subjected to the action of the acids aa
directed for the preparation of earths, to get rid of the lime
salts. The partially cleaned deposit, which is now much
smaller in bulk, must he separated as much as possible
irom the liquid, strong sulpharia acid, in sufficient quantity
to cover it, poured on to about the depth of half an inch,
and heat applied and contioucd for sometime, but the liquid
mast not be made to boi!. The result will be an almost im-
mediate blackening of the liquid, which gradually becomes
deeper, and a dirty, inky-looking compound is ultimately
produced. When this has taken place, chlorate of potash
in fine powder must be dropped into the hot misturo very
graduaily until the black colour disappear. This must be
dona cautiously, for the action is bo violent, that much
spurting is occasioned ; and the liquid being very corrOBive,
a tolerably capacious vessel should be uued in order to keep
the splashes within reasonable bounds, or serious damage to

73

tbe operator'a clothea laay ensile. Tbe nearly decoloi
IJqaid must now be dilated witb a considerable qnaatitj a
water, and tlie deposit allowed to subside, the enpernatanl;
liquid ponred off, and the procesa of heating with snlpliDriafl
acid and addition of chlorate of potash repeated until ihsfl
Bulpburic acid occasion no further blackening; then tlittl
cleaning may be finished in the usoal waj by waBhing."

I have had many complaints from mj frieude that witltj
all their care they have found nothing fit for moDuting ii
gnano. This is readily acconnted for by one fact, that noi
one sairple in twenty of what 18 called guano in tbe mark^
haa an atom of guano in it. Procure real guano, and JOitfl
will get real returna.

Tbe foBBil Infusoria (as they were formerly called) are Dowfl
termed Diatomaceio, and are found in various parts of the J
world ; such as Bermuda earth, Berg-roehl from Norway, tlio
depoait from Monrne Mountain in Ireland, &c. They are
found in imnenae quantities, and afford the microecopiat
innumerable objecta. The same treatment as that UBoallj
employed for tbe Diatomaceie must be followed nith t*
deposita; but as they are sometimes obtaiopd in hard mai
diaiatpgration is first necessary. To effect this, they a
usually boiled for a sbort time in diluted Uqiuir j
which will soon cause the maas to fall into a n
deposit. Water muat then be iramedialely added, i
that all further action of the liqaor potasea; may be stoppofljij
otherwiae tbe objeota aearched for will be disaolTed. For tl '
reaaon it ia neoeaaary to understand what aubatauce is being J
dealt witb, because aome depoaita are much finer and ara ■
acted upon more readily than others.

In moanting these objeete, some are so delicate that t
are almoat invisible when balsam is used with them ; t
ore therefore nanally moonted dry. Othera, however, a
much coarser, and rnay be nonnted in balaam like tbe D
macesa mentioned in Chapter IV.

The common Infuaoria cannot be mounted dry with, k
great success, though a few may be placed upon the glai

riiile and allowed to dry oatDrally, vihen ibeit cbaractera
will be rery well ahomn. To obtain anytbing like a natural
appearance, they mnat be put up in fluid aa iu Chapter V.

Next to the DiatomaceEB, no class of microscopic objeota
has been more looked into of late than the Forarainifera.
These animala are almost all marine, having a jelly -lite body
encloBed in one or more chambeTB of shell, which ia generally
composed of carbonate of lime. The sbella are made with
mintite orificea, throogh which the psendnpodia (falae feet)
are extended by which the animal is enabled to lay hold of
anything to draw itself along. From the possession of these
orifices they derive their name, aa foramnt means a- door or
opening. They have been found in every depth of aea
hitherto eoaoded, each depth being abundant in certain
ipecies; the lowest beds containing the greatest namber of
fpeoimens, though with less variation of kinds. In chalk
they are found in a fossil state, and may readily be shown
(seo Chapter IV.) ; in limestone and other hard stones thoy
are abandant, and some monDtaioH are composed principally
of these shells.

The methods of obtaining Foreminifera are various. Many
may be found upon seaweeds, which should always be ex-
amined as soon as possible after gathering. They are foand
in maases upon some coaata where the wavea have carried
and left them ; but they are to be found the most abundantly
in sand or mud dredged from the bottom of the sea. They
mnst, however, be cleaned and separated from the mass of
impurity with which they are usually mistd. This may be
done in various ways, according to the natnre of the accom-
panying matter. If sand alone, as ia frequently the caae,
the whole mass mnst be thorough!!/ dried, and then stirred
np in clean water. The sand will soon eabside by ita ovn
weight, but the chambers of the Foraminit'era, being filled
with air, will flont upon the Burfaoe, and may be skimmed
off. There u, however, one objection to this mode of pro-
ceeding—some of those objects are so minute, the chambers
containing comparatively so small a quantity of air, that

74

they sink and are caat awaj with the refuse eand. On thi
acooant it is preferable to take the trouble uf searchin
certain soundings ncder the microicope, i
hflir pencil, or some other contrivance before mentioned, 1
extract tboBs objects which are required.* To clean tliBl
Foramiaifera, FroresBor Williamson adviaes tbe transfer of^
the specimens to an evaporating dish containing a weak |
solntioa of caustic potash. This must be boiled for f
moDieats, nben the organic matter will be entirely dissolved, I
and the calcareoas shells lefl free from imporitf. They J
moHt con be well washed in water, so that all alkaline'^
matter may be entirely removed.

If the specimens are in mud, we most proceed in a dif- I
ferent way; — Stir up the whole maaa in water, and alloT f
it to stand nntil the heavier portion has sunk to the bottom;'
the water may then he ponred off and examined to e
tbere are any objects contained in it. This process mnst ba 1
repeated nntil the water come off qnite clear, when (if the m
search is for ForamiDifera only] the solution of canstio^
potash may he used as before mentioned. However th
soundings, &o., are cleaned. It is necessary to assort tiien

* In Hearching any earth or sounding: in order to take objects tbero-
from, DO methnd pre«:nt9 the Eame fndlitioa aa the uaa of Ihe GneHt
camel-hair pencil, to whiah, after being drawn through tha lips, any
forma will adhere, and yet be readily detached upon tbe slide. AFtOT
Imailest objects may be separated. Captain Ijang,

dip pi

led ii

power. With Bi rcrj fine hi
about 1,1(10 Blidea, eaob
h had from

Ita adh^va
iring one winter I mounteit
t of sea soundinga, roany gf
upon them. The rendineas
lint and were detaohod. »'

wibh which the objects adhered to the
required, Teadcredtheproaeasmuch mc
with gum. As to the numbers of objet
ing, even imagination often faila. Plaiious, it is said, onlleoted 6,1
shells of Foruminifera from ftn ounue of sand fiom the shore of L
Adriatic. Soldani oollected from lesa than an ounce and a. hail
roElc from the hills of the Ca^-eiana, in Tuseatiy, 10,46i tonal Bbi
Several of these were ao minute that 500 weighed only a grain, j
D'Orbigiiy found :!,81D,0D0 epeoimena in an ounce of sand from
Bhures uf the Antilles.

OF MICROSCOPIC OBJECTS. 75

der the microBCope with the camel-hair pencil or other
eontrivaiice, as it is impossihie to oLtaiu them fit for mount-
iog without Dodergoiog thia proceBS.

The Bea soandings taken by order of Govertitnent are
drawn from the bottom in a Itind of apparataa ingeniooBlf
made for the porpose, and the sand, mud, &c., are brought
in their original state. Common Booodiugs, however,

I taken hj loneriug a heavy piece of lead coated with
tallow, which conseqaentlj brings np a small portion of the
matter from the bottom, Mr. George Mosley, the late
Secretary of the Manchester Microscopic Society, obtained
numbers of the " scrapinga " from the soonding leada. To
inalie any use of these it is, of oonrae, neceaaary to free them
from all traces of the tallow. Mr. Dancer places the sound-
ing in a basin aud pours boiling water opon it, which causes
the melted grease to rise to the surface. When cold, thia
may be removed, and the water carefully decanted. The
operation may be repeated until no grease appears, when
the water may bo withdrawn and liquor avimonim naed,
which will form a soapy solution with any remaining grease.
Thia must be treated with hot water for the final waahlag.
Care most be taken leat the finer forms be carried away in
decanting the washing liquid. Should it be wished to make
certain as to this point, each washing should be examined
under the microscope. In some cases the process of Mr,
Dancer will prove sufficient. Mr. Dale, however, gives a
method of acoomplishiog the same result, which is much
more readily completed; and as no fault can be found with
these results, I will here give it in foil ; It is now well known
that one of the products obtained from the naphtha of coal-
tar ia a volatile, oily substance, termed henzole (or, by
Prench ohemista. benzine), the boiliog-point of which, when
pure, is about 180° Fahrenheit, and which is a perfect
solvent of fatty substances. In a capsule, previously
warmed on a sand-bath, Mr. Dale mixes with the tallow
Eonndinga aome of thia benzole, ontil diluted so as to rnn
freely, pressing the lumpa with a glnas rod until thoroughly

AJID MOCNTISG

mingled ; the solation and its contents are tlien ponred ioti
a paper filter, placed in a gla,ae funnel ; the capsule ia aga.iii
washed with banzole, until the whole of the gritty particlei
are retnoved into the filter. A watthing-hottle ia then sup-
plied with benzole, and the eontenta of the filter washed to-
the bottom nntil the liquid passes off pare, which maj bel
tested hf placing a drop from the point of the funnel
warm alip of glae» or bright pUtinum, when, if pure, thQ'
benzole will evaporate without reaidae or tarnish ; if greawJ
he present, the washing mnat be continned nntil thej ars,
free from it. After riaaing through weak acid, or alcohol,
for final purification, the calcareoQa forms will be read; for
mounting.

Tha filter audita contents maybe left to dry spontaneously,
when the latter can be examined by the microscope. Should
time be an object, rapid drying may be effected by any of
the naual methods ; one of which, recommended by Mr,
Dale, is to blow a stream of hot air through a glass tnbe
held in the flame of a. Baasen'a burner, The loner the
boiling-point of the benzole, the more readily can the
gpecimena be freed from it. A commoner quality may ba
nsed, bnt it ia more difficult to dry afterwards.

Pare benzole being coatly, this may appear an expenaiTa
process ; bnt, with the exception of a trifling loss by
evaporation, the whole may be recovered by simpli
tillation. Tho mixture of tallow and benzole being placed
in a retort in a hot-water, a steam, or a sand bath, ths
benzole will pass into the receiver, and the tallov or other
impnritiea will remain in the retort. When the whole of
the benzole baa distilled over, which is ascertained by its
ceasicg to drop from the condenser, the heat iswithdrann.
and the retort allowed to coot before the addition of freah.
materia!. Half a dozen to a dozen filters, each with itt
specimen, can be in process at the aame time ; and the dia--
tillation of the recovered benzole progreasea as quickly
the filtration, which was practically proved on
^ named. The process is very dangerous and great caution

OF MiCROscoric OBJECTS. (7

ia to be naed In the approaoii of light to the inflammaLle
vapnur.

After the Foraminifera and calcareoaa formg have been
removed, the residue may be treated viith acids and leviga-
tion in the usual manner, to obtain siliceoas TormH aud
discB, if there be any present ; bnt to facilitate their
depoaitioB, and to avoid the loaa of any minute atoms
Guspeniled in the washings, I would suggest the nee of
filtiatioD. The conical filter is nusnitable, aa the particles
would spread over too great a Borface of paper ; but glass
tnbea open at both ends (such as broken teat-tubes) will be
found to answer, the broad end covered with filtering -paper
and over that a slip of muslin tied on with a thread to
facilitate the paasage of the water and prevent the risk of
breaking the paper. Snapend the tobe over a snitable
vessel throngh a hole cut in thin wood or cardboard, pour
in the washings, which can be thns filtered aud then dried.
The cloth must be carefully removed, the paper cut ronnd
the edges of the tube, and the diatoms on the paper disc
may be removed by a camel-hair pencil or otherwise, ready
for monnting. Thus many objects may be preserved which
nonld he either washed away or only be obtained by a mori.
tedions proceBS.

Such is Mr. Dale's method of cleaning the aoundinga
from tallow, and as it thoroughly accomplishes its end, and
ia alike efFentive and not injurious to Foraminifera and dia-
toms, it maybe safely reaommended. The weak solation of
oattstic potaah before advised for Foraminifera, must not be
naed where it is desired to preserve the diatoms, as they
Tvoold certainly be injured, or destroyed altogether, if this
agent were employed.

In filing the Foraminifera upon the slide, no better plan
can be followed than the dry cells and gum recommended
in the early parts of this chapter. Owing to their thiotnesa
and composition, moat of them are opaque objects only ; but
they are eiqniailely beautiful, and require no particniar care,
except in allowing the cell to be perfectly dry when

L Cli&

78 PREPiRAnoN ABD MOCSTISO

the oover is placed upon it, or tbe damp will certaiolj
become condeaaoJ apan tbe inner side, and the examinatioii
Berionaty hindered.

Many of the ForamiDiferai require catting into sections if
it ia wished to examine their internal atTnctnre ;— -" decal-
cifying" ie alao desirable ia some cnaee : botb of thea
procesaea will be roonil described at lengtb ia tbe chapter oa
Sectiona and DisBecttona.

When more than one apccimen of some particnlar a'
obtained, it is better to place them npon the elide i
fereot positiona, ao as to show aa much of the Btractore a.
poaaibie. I will cooclade this subject by quotjag a
I from T. Eymer Jones: "It is, therefore, by no meana Bn&
I ficieut U) treat these ahells as ordinacj objects by sitnpljf
laying them on a glaas alide, ao as to aee them only from
one or two points of view ; thej mnat be carefully examined
in every direction, for each ia the di»eraity of farm thi
nothing short of this will be at all satisfactory. For th}
purpose, they should be attached to the point of a ~
needle, ao that they may be turned in any direction, i
eiamined by reflected light condensed npon them by □
of a Jena or side reflector. In many of the thick-shell
speeiea it will be neceaeary to gi-ind them down o
[aee Chapter VI.] before the number and arrangement s
the internal chambers is discemible ; and in order 1
inveatigate satisfactorily the miantiie of tbeir Btrnctara^
a variety of Sectiona, made in various wayi
■ pen^able."

A viaitor to the seasiJe may with little trouble procnra
)ne of the most beautiful objects which can ornament B
cabinet. On turning over atones which have been ft
by the last tide, a very small species of starfish will often b
met with. From a small circular centre f
project, each of which ia covered with spines beautifully
arraoged. When found, they should be dropped into fredl
water with a little spirit added. This tillEs them instantly,,
elaa many of tbeir long arms get broken by their struggles.

fW SICSOCCOFIC OBJECTS, 70

B; poUang Oan into wster the arma sre rendend, toft and
Mtsf tbas be ^nad in forms beat saiud to mitxroBOO{ilo
■Hdcii, nod tliiu nSowcd to drj. They are be*alifuUx
ddicat« in ooloar, needing no preparatioD to lil«a«h tlicni,
Dviing tme mraning'a walk at Llaadudiio I pruciirod aboul

Plants aSbid an almost ioeihanstiblo trcnsiiry for tho
Hiicroscope, and maoj of tbem ehon their b«autii>s best wk^ii
moanted drj. When aoj of these are to be uouDtad, e»n
mnat be taken that they are tbornaglily dr?, otliervriin Ihd
damp will certaiulj aii^e in the cell, aad iujiiru the objoctt
and it may here be mentioned that long utter n luaf hiiM
erery appearance of dryness, the interior ia hUII dikni[>, and
no waj can bo recommeDded of getting rid of tliis by any
qnicker process than that of keeping thou in a wnrnt room,
aa many leaves, &c., are ntterly spoiled by using n hot irou
or other contrivance. The safest way is to jirrsii ihcin
gently betwist blotting-paper, which inny bt! rfniuTt-iI niid
dried at abort intervals; and though this uiay tipiH'ur u
tedioos operation, it is a so/s one.

On the sarfacB of leaves, haira aod scales of vuriuiiB and
very beantiful forms are found, most of which display their
beauties beat when removed from the leaf, uiid usoj with
the polarizer. These will be noticed in another plaoii-, but
a portion of the leaf should always he prepared iti its nuturnl
form, to show the arrangement of the hair or seules uj>on it i
and this must almost invariably he mounted diy vrltvn UKi'd
for this purpose. Many of them rer[oire very iJelii!Uto
handling. The epidermis, or, as it is by some tornieil, tho
cuticle, is the onter skin which lies upon the surfiine of tbu
leaves and other parts of moat plaots. This ia compaaud of
cella closely connected, often bearing the appnurunuo of a
rude network. In many plants, by scraping up the surface
of tbe leaf, a tbin coating is detached, which may be tatu
off by takiag bold of it with forceps. The piece may thou
be washed and Soated upon a glaas slide, where, on dry-
ing, it will be firmly Eied, and may usually ho mounted

80 PREPARJTIOS AND UQUSTISH

drj. AmoDgat the most beaatifu) and ea,ei\j prepared (
these maj be meatioDed the petal of tlie geraaiam, ths
cells of nhich are well de&aed and amoDgst the most
in te resting.

Sometirnea this ciitifle is removed b; maceration oE
leaf in water or by a quicker method — boiling in nitric acid
Perhaps it will be aa well to gi»B Mr. Arnold's experience
"A leaf of a rhododendron which bad been drj sodh
months, and a freBh I; -gathered leaf of an azalea, were put inbl
a teat-tube, and covered with undiluted nitric acid of oon
marce of, I believe, about 1'3'2 specific gravitj ; the tobe ml
held over a, Bpirit-Iamp nntil the acid just boiled, a«
the contents were then throtrn into a basin of cold watef
The cuticle of tbo rhododendron leaf partially aeparatat
spontaneonaly ; that of the azalea came off without thi
least difficulty. The whole operation did not occupy mon
than five minutes. Undoubtedly many leaves, according ti
their texture, will require different strengths of acid, o-bA
longer or shorter periods of boiling."

Closely connected with the leaves are the anthebs an^
FOLLBN, of which a great uambor are beautiful and intereating
sahjeota for the microscopiat.

The mallaw tribe will faroish some exquisite objeet^f
beariug the appearance of masses of costly jewels. The«a
are usually dried witb pressure, but the natural form ma
be more accarately preserved by allowing them to dry i
they are taVeu from the flower, with no ioterferenoe except
thoroughly protecting them from all dust. Sometimes the
anther is divided, so that the cell required to receive them
may be of as little depth as possible. The common mallow
is a beautiful object, but I tbink the lavatcra is a better, as
it shows the polleo-chambera well, when dried unpressed.
The pollen is often sat alone, and is well worth the trouble,
as it then admits of more close examination. Oftou it is
convenient to have the anilier and pollen as seen io natore
on one slide, and the poUtn alooe upon another. The
former sboald be taken Jrom the fiovrers before their full

OF MICBOSCOFIC OBJECTS. gl

deTelopment ia attained, aa, if overgrown, they lose ninch of
their beanty. Some pollens are naturally ao dark that it is
necesHary to moant them in Canada balsam or Said, as
deBcribed in other plaoea; but they are better mounted dry
when they are not too opaque.

Here we may also mention the seeds of many plants as
most interesting, and some of tbeni very beantifnl, objects,
requiring for the greater part bot a low power to show them.
Most of these are to be monnted dry, as opaque object?, in
cells suited to them, but some are best seen in balsam, and
will be mentioned in Chapter IT.

The CoBALLiSES, many of which arc foond on almoafc every
coast, afford some very valuable objects for the microscope.
They mast be well washed when first prociired, to get rid of
all the salts of the sea-water, dried and mounted in cells
deep enough to protect them from all danger of pressure,
e of them are exceedingly fragile. The white ivory
appearance which some of them present is given to them by
1 covering of carbonate of lime ; and shoiild it be
desired to examine the structure of these more closely, it
may be accomplished by keeping them for some time in
vinegar or dilute muriatic acid, which will remove the lime
and allow of the substance being sliced in the same way aa
oOier Algfe. {" Miorographic Dictionary," p. 183.)

Tkb Scales op Insects. — The fine dust upon the wings
)f moths and butterflies, which is so readily removed when
they are bandied carelessly, is what is called the scales. To
these the wing owes the magnificent colours which so often
are seen npon it ; every particle being what may be termed a
distinct £at feather. Row these are placed (somewhat like
tiles upon a roof) may be easily eeen in the wing of any
butterfly, a few being removed to aid the investigation,
" Their form is naually that of the battledore with which
the common game is played, but the handle or base of the
scale ia often short, and the broad part varits in propor-
tionate length and breadth in different specimens. The
markings upon these also vary, some being mostly composed

82 PBEFAEATION AND HOUKTIKG

of lines rnnning from the base to the apex, others reminding
ns of network — bead-like spots only are seen in some —
indeed, almost endless changes are fonnd amongst them.
These scales are not confined to batterflies and moths, nor
indeed to the icings of insects. The different gnats sapplj
some most beautiful specimens, not onl^ from the wings,
bat also from the proboscis, &c. ; whilst from still more
minate insects, as the podura, scales are taken which are
esteemed as a most delicate test. The gorgeoas colours
which the diamond beetles show when under the microscope
are produced by light reflected from minute scales with
which the insects are covered.

In mounting these objects for the microscope it is well to
have the part of the insect from which the scales are nsaallj
taken as a separate slide, so that the natural arrangement
of them may be seen. This is easily accomplished with the
wings of butterflies, gnats, &o. ; as they require no extra-
ordinary care. In mounting the scales they may be placed
upon slides, by passing the wings over the surface, or by
gently scraping the wing upon the slide, when they mnst be
covered with the thin glass. Of course, the extreme tenuity
of these objects does away with the necessity of any cell
excepting that formed by the gold-size or other cement nsed
to attach the cover. The scales of the podura should be
placed upon the slide in a somewhat different manner. This
insect is without wings, and is no longer than the common
flea. It is often found amongst the sawdust in wine-cellars,
continually leaping about by the aid of its tail, which is
bent underneath its body. Dr. Carpenter says : — " PodursB
may be obtained by sprinkling a little oatmeal on a piece
of black p^er near their haunts ; and after leaving it there
for a few hours, removing it carefully to a large glazed basin,
so that, when they leap from the paper (as they will when
brought to the light), they may fall into the basin, and may
thus separate themselves from the meal. The best way of
obtaining their scales, is to confine several of them together
beneath a wine-glass inverted upon a piece of fine smooth

or jocBOTCOPic QftrecTS. 83

paper ; for the scales will become delated hj Uieir leipB

against the glaaB, aad wiQ Ml gpon Uia p^to-." Thno
seales are removed to the elide, and moaoted ta those frcna
goats, &c. When the podara has been caoght withoat the
aid of meal, tt maj be placed upon the shde, under a test-
tnbe, or by anj other mode of confiDemeut, and thus save
the tronbla of transfer from the paper before meolioned.
Another method is to seize the insect bj the leg with the
forceps and drag it across the slide, when a Eufficient qnan-
tit; of scalea will probably be left npon it.

Mr. Mclntyre procnrea the scales in the foUowing man-
ner : — He makes what he l*rms a breeding-e^e, by taking
a piece of plate-glass four inches long by two iochei wide,
and over this places a few sheets of blotting-paper. Upon
these he lays a aheet of cork about a quarter of an inch
thick, with a circle cot out of the centra one inch wide.
This gives a kind of box, which he covers with gla^s, kept
firm by two elastic bandB. He says ; — " After capturing
the insect by means of a tnbe and a camel-hair pencil, I let
it remain for some days in one of the breeding-cages, into
which I always transfer the newly -cnnght podura, until it
has changed its skin ; then I stupefy it with chloroform,
and drop it out on to a thin glass cover (previously cleaned)
and with a very clean needle-point roll it backwards and
forwards npon the cover till enfficieut scales are removed.
A very light pressore is indispensable, so as not to sqaeeze
out any of the insect's fluids."

These scales are usually mounted dry ; but Hogg re-
commends the use of Canada balsam (Chapter IV.) as ren-
dering their structure more definite when illuminated with
Wenham's parabolic reflector. Some advise other methods,
which will be mentioned in Chapter T. As most insedg
when undissected are mounted in Canada balsam, the dif-
ferent moiies of treatment which they require will be stated
in another place.

In mounting blood of any kind to show the corpuaeles,
or, as they are often called, glahvXee, which are round or

81 PIlEPillAIlOK iSD

oval discs, it is but necessary to cover the alide on tlie spot
required with a coatiog as thin as possible and ailon it to
dry before covering nith tliin glass. There is a slight con-
traction in the globules v>heii dried, but not enough to in-
jure them for the mioroacope. The shape of these varies in
different cIbsbcb of auimalB, bat the size varies much more,
some being mainy times larger than others. Perhaps it nil!
not be out of place to say a few words concerning the detec-
tion of blood. Wherever the stains are, they must be care-
fully scraped avay and immersed for a few bonrs in a wesik
Bolutioa of bichloride of mercury. With a thin tuba tie
more solid portion may tlien be removed toa glass slide and
examined with a somewhat high power. A slight knowledge
of the microscopic appearance of blood-discs will show m
whether the suspicion of blood is correct.

Some of the skins of lamtB are beantifol objects ; bot, Uka
many sections of animal and other fragile matter, are diffl-
cult to extend upon the elide. This difficulty is easily OTei>'
come by floating the thin object in dear water, immersing,
the slide, and when the object is evenly spread gently lifting-
it. Allow it then to dry by slightly raising one end oi
the slide to aid the drainage, and cover with thin
other objects. The tails and fins of many small fiah ma,f

a similar i
trouble.

A few objects which ai
may be here mentioned e

)ogh some of them '1

1 well worth Iht'

re best shown by mounting drf'
a a slight guide to the beginner
e been before noticed. Many of.
the Foraminifera, as elsewhere described. Some cnjsialg are
Bolnble in almoet any UuJd or balsam, and should be monnted
diij; a few, however, deliquesce or effloresce, which renderf
them worthless as microscopic objects.

The wings of botterflies, gnats, and moths will affoni
many specimens wherewith to supply the cabinet of ti^
young stodent. A great variety of scales also may be ft
amongst the ferns \ indeed, these aloue will afford 1
student occupation for a long time. On the nndei

p Kicuoscopic c

65

the leaTBB are the reservoirs for the aparea, which in maoy
inBtancea aomewhat reaemble green velvet, and are arranged
in atripeB, round maases, and other forms. The aporea are
QSQEill; covered with a thin akin, nhich ia oariouBlj marked
in some specimens, often very like pollen-graina. The man-
ner in which these spores with all their accompaDiments
are arranged, their changes and developments, afford almoBt
endleaa anbjects for atudj; different ferns presenting uh with
maoj variationa in this reapeot totally inviaiblo withont the
aid of the microscope. The hymenophylloma (of which two
only belong to England) are particularly interesting, and
the alroctare of the leaves when dried makea them beantifnl
objects, often requiring no balaam to aid thoir transparency.
Portions of the fronds of ferna should be mounted aa opaque
objects, after having been dried between blotting-paper,
when they are not injured by pressure ; bat care must be
tahen to gather them at the right time, aa thej do not show
their beaotj before they are ripe, and if over-ripe the ar-
THugemeut of the apores, &•:., ia altered. The aporea may
be mounted aa separate objecta in the aame manner as
pollen, before mentioned, and are exquisitely beautiful when
viewed with a tolerahly high power. The number of foreign
ferns now cnltivatcd in this country baa greatly widened
the field for reaearch in this direction ; and it may also be
mentioned that the under-sides of many are found to be
covered with scales of very beantifnl forme. A small
piece of the frond of one of these may be mounted in its
natural state, but the removal of the scales for eiamina-
tiou by polarized light will be deacribed in another place.
The moaaea alao are quite a little world, requiring but a low
power to show their beantiea. The leaves are of varioua
forma, aome of which reaemble beautiful net-work ; the
" urns" or reaervoira for the spores, however, are perhaps
the most interesting parts of these objects, aa alao of the
liverworts which are closely allied to the moasea. These
nrna are generally covered by lida, which fall off when
the fruit is ripe. At this period they are well fitted for the

86 PBEPiBATION ASD MonSTISQ

microscope. The common Bcrew-moss may be foond in
great abuudance, and sbows this denudation of the Hporea
very perfectly. Many of these may be easily dried without
roncli injury, but they shoald also be examined in thnc
natural state.

The Btudent should nob omit from his cabinet a loaf d
the nettle and tlie allied foreign Bpecies, the mystery
which the microscope will make plain. The bairs or uting
may also bo removed, and viewed nitb a higher power thai
when on the leaf, being so transparent as to require a
sam or other preservative.

There are few more interesting objects than the raphido
or plant-crystale. These are far from being i
Bome plants they are very minute, and oonsoqoeiitly reqnin
care in tbe mounting, as well as a high magnifying powa
to render them viaible; in others they are so largo that
about twenty-five of them placed point to point would reach
one inch. Some of these crystals are long and compara-
tively very thin, which suggested the name (raphie, a
needle); others are etar-lil<:e, with long and slender rays]
while others again are of a somewhat similar form, e
being solid and short. If tho stem of rhubarb, or
any of the hyacinth tribe, be bruised, so that the jni
flow upon tho slide, in all probability same of these cryo'
tals will be found in the fluid. To obtain them olean,
they must be freed from all vegetable matter by maceration^
After this they must be thoroughly washed and moant«d
dry. They are also good polarizing objects, giving bril-
liant colours; but when used for this purpose they muit
be mounted as described in Chapter IV. A few plantii
which contaia thetn may be mentioned here. The Cao-i
taeeiB are very proliBc ; the orchids, geraniams, tulips, aai
the outer coating of the onion, furnish tho more unnsnat
forms.

The Fungi are generally looked upon as a very difficult
elaas of objects to deal with, but amongst them some oL
the most available may be fonnd. The forms of many ara

OP MicEoacopic OBJECTS. 87

very beantiful, bnt are so minute as to require a liigh mag-
nifying power to show them. The mould which forms on
man; HubBtaoces is a fungua, and in some cases may he
dried and preserved ia ita nataml state. A friend of mine
broaght rae a roae-bush completely covered with a white
Wight. This was found to be a fnogus, whioh required a
high magnifying power to show it. Being a very interesting
object, it was desirable to preserve it, and this was perfectly
effected without injury to the form by simply drying the
leaf in a room nsnally occupied. Amongst the fungi are
many objects well worth looking for, one of which is the
Diack^EO, elegnnB. This, tlie only Bpeoies, says the Micro-
grapbia Dictionary, ia found in England upon the living
leaves of the lily-of-tlie -valley, &c. Theae little plants grow
ia moases, reminding one of mould, to a height of a quarter
of an inch, and each " stem " is covered with a aheatb, in
shape somewhat like an elongated thimble. When ripe the
sheath falla oS aod reveals the same shaped column, made
up of beautifully fine networi, with the spores lying hero and
there. This dries well, and ia a good object for the middle
powers. Amongst tbe fnngi the blights of wheat and of
other articles of food may be included. Many of them may
be mounted dry; othCTS, however, cannot be well pre-
served except in liquids, and will be referred to in Chap-
ter V. When rambling in a wood during the sammer I sat
down upon the fallen trunk of a tree, and here and there a
few minute white spots caught my eye. I toot my Cod-
dingtoD Ions from my side-pocket and applied it to these.
Judge of my surprise when I fnund each white speck a
diatinotly formed fnngos resembling in Biie and form, to an
amusing similarity, a disc of the atachnoidiaous. They were
already dry, and I monnted them aa ordinary dry objects ;
and hitherto no change has taken place which I can detect.
Amongst the Eoophytes and eea-mats, commonly called
sea-weeda, may be found very many iuteresting objects to
be monnted dry. WUen this mode of preservation is used,
it ia necessary that all the sea-aalt be thoroughly waahed

S3 rKEPARiTion axd mountikg

from them. As tbej are, however, moat frequently rooonted 1
in balaam or liquid, tbej will he mora fully noticed in other f
places.

The scales of fishes are generally mountad dry when
nsed as ordinary objects; but for polarized light, balsam o
liquid must be need, bb noticed in Chapter IV. To nionnt
a fish-scale, however, in q satiafactory manner, cara roust be
taken that it ia perfectly clean. Tbia can be accompliahed
only by careful washing, in which proceas soft cnmel-hair
pencils will often be useful. When the Blime or mucas haa
once dried, it ia very difficult to remove. Tbe variety and ,
beauty of these are quite surprising to the novice,
also very interesting to procure tbe sbin of tbe fish ^
poaeible, and mount it on a separate slide to ahow hon
scales are arranged. The sole ia oue of the most unasnal |
forma, the projecting end of each scale being covered witk I
spiuen, wbicli radiate from a common centre, while those at 1
tbe eitremity are carried out aomewbat TOaembling the raya I
of a star. One of the akatee has a spine projecting from tba 1
centre of each scale, wliich ia a very curious opaque object, I
eapecially when the skin ia mounted in tbe manner deBcribed.
The perch, roach, minnow, and others of the common fishes i
give the student good objects for-his cabinet, and may be <
procured without difficulty, Tbe scale of tbe turbot is a
splendid object for the pol aria cope when mounted in balsam.

Insects wbich are very transparent, or have tbe " metallio
lustre" with wbich any medium would interfere, a
dry. The diamond -beetle, before mentioned, is a splendid J
example of this ; tbe back is generally used, but the legs, ,
showing the curious feet, are very interesting o' '
deed, amongat the legs and feet of insects there ia a wide- f
field of interest. When they are of a horny nature, it ie
heat to dry them in any form preferred, but to use nt
pressure; when, however, they are wanted fiat, so as it
show the feet, &c., eitended, they must be dried with a J
gentle pressure betwixt blotting-paper if possible. But this J
will be treated more fully in Chapter IV.

ehonld i

of crabs. You c
deceived when yi

e aicKoscopic objects. 89

syrm ofiiucctg are Hometimes allowed to dry in their
natural shape, and mounted as opaqne ohjecte ; but generallj
they are naed aa tran spares c lea in balsam or liquid, ho the
description of the treatment which they require will be
deferred to Chapter IV.

Hairs, when not too dark, are sometimes transparent
enough when monnted dry, hot are usoally moanted in
baleam. These will be more fully noticed in another place,
but there are some without which no cabinet ia deemed in
anynise complete. Many different species of bats, English
and foreiftn, present us with hairs the form of which we
dared to imagine without microscopic
s objects are found in the anteunm
also readily know whether you are beiug
bny what you deem a. real sealskin or
sable, from some of the common caterpillars I have ob-
tained exquisitely beautiful slides, and a kangaroo is a true
friend to an object -gatherer.

The hair of the ornithorhynohns is a very cnrions object,
baving- a thin place in the middle of its length, and so pre-
senting somewhat the appearance of a flail.

These are a few of the objects which are often monnted
dry, but some of them sbonld he shown in balsam or liquid
also, and there is much difference of opinion as to the best
way of preserving others. This, however, is eiplained by
the fact, that the transparency which balsam gives, inter-
feres with one property of the object, and yet develops
another which wonld have remained invisible if preserved
dry. The only method of overcoming this difficulty is to
keep the object mounted in botli ways, which is comparatively
little trouble.

I may here mention that many prefer the lieberkuhn
for the illumination of opaque objects; and a good back-
ground is gained by putting opon the undor-side of the
elide, immediately beneath the object, a spot of black varnish,
which does not interfere materially with the light,

90 PBEFABAIIOK AND MOUNTIKO

CHAPTER IV.

HOUNTINO m CANADA BALSAM.

The natare and use of this substance lias been before spoken
of, so that the method of working with it may be at once
described.

Perfect dryness of the objects is, if possible, more neces-
sary in this mode of mounting than any other, as dampness
remaining in the object will assuredly cause a cloudiness to
make its appearance in a short time after it is fixed. Where
pressure does not injure the specimens, they are most suc^
cessfuUy treated when first dried betwixt the leaves of a
book, or in any other way which may prove most convenient,
as noticed in Chapter III.

Before describing the methods of proceeding with par-
ticular objects, general rules may be given which should be
observed in order to succeed in this branch of mounting.

As the object is to be thoroughly immersed in the balsam,
it is evident that when it has once been covered, so it must
remain, unless we again free it by a process hereafter men-
tioned, which is very troublesome ; and on this account there
must be nothing whatever in the balsam except the object.
The inexperienced may think this an unnecessary caution;
but the greatest difficulty he will meet with is to get rid of
minute bubbles of air, perhaps invisible to the naked eye,
which appear like small globules when under the microscope,
and render the slide unsightly, or even worthless. Balsam
dissolved in benzole will be found invaluable in mounting
without air-bubbles ; if a few are left in the specimen, by
the next morning they will have entirely disappeared. In
making this solution the balsam should be first boiled
gently till on dropping a small quantity into water it is

OF MICKOSCOPIC OBJECTS. 91

ibimd to he aa hard aa tesio, the Boftened and warm Eolution
may be now poured into a bottle, and when cool the benzolo
added in sufficient qnantity to make it of a desirable thick'
nesB. Ten objects oat of eleven contain air, or at least aio
fall of minute holes which are necessarily tilled with it ; so
that if they shonld be immersed in any liquid of thick
consiatency, these cella of air wonld be imprisoued, and
become huhhles. The air, then, must be remored, and this
IB nsaally accomplished by fioabing for ioma time iu tarpen-
yne, the period required differing according to the nature of

9 object. In some cases, the turpentine acta upon tho
colour, or even removes it altogether, so that it must be
watched carefally. Often, bonever, this ia an advantage,
as where the structure alone ia wanted, the removal of the
colouring matter rendera it more transparent. There arc
objeetB, however, which retain the air with snch tenacity
that Boaking alone will not remove it. If these will bear
beat without being injured, they may be boiled in turpentine,
' I balaam, when the air will be partly or totally
erpelled. Uut where heat is objectionable, they muat be
immersed in the turpentine, and so submitted to the action
of the air-pump. Even with this aid, sometimes daja are
required to accomplish it perfectly, during whieh time the
air should be eihanated at intervals of five or aii hours, if
convenient, and the objecta turned over now and then.

Many complainta are made concerning turpentine, both
u to ita cleanliness and penetrating power. Most of these
spring from the fact that few substances in the market vary
a mnch as turpentine in purity ; all aorta of rubbish are
Bold nnder this name, and now benzole is employed by many
'n alt cases where turpentine aloae was once used.

Sometimes the objects are so minute that it is impossible
to anbmit them to any soaking, and in this case they must
be laid upon the slide at once, and the turpentine applied
to them there. But it mnst not be forgotten that there are
- Borne few which are much better mounted in such a way
that the balsam may thoroughly surround, and yet not

90 PEEPAEATION AKD MOUNTING

CHAPTER IV.

HOUKTINO m CANADA BALSAM.

The natare and use of this substance has been before 6pok<
ofy 80 that the method of working with it may be at on
described.

Perfect dryness of the objects is, if possible, more nec<
sary in this mode of mounting than any other, as dampn>
remaining in the object will assuredly cause a cloudiness
make its appearance in a short time after it is fixed. Wl.
pressure does not injure the specimens, they are most !^
cessfuUy treated when first dried betwixt the leaves o
book, or in any other way which may prove most oonvenit
as noticed in Chapter III.

Before describing the methods of proceeding with -
ticular objects, general rules may be given which shoul
observed in order to succeed in this branch of mountin*^

As the object is to be thoroughly immersed in the bal
it is evident that when it has once been covered, so it i
remain, unless we again free it by a process hereafter .
tioned, which is very troublesome ; and on this acoouut
must be nothing whatever in the balsam except the i'
The inexperienced may think this an unnecessary cai
but the greatest difficulty he will meet with is to get .
minute bubbles of air, perhaps invisible to the nake«'
which appear like small globules when under the micro
and render the slide unsightly, or even worthless. E
dissolved in benzole will be found invaluable in mo:
without air-bubbles ; if a few are left in the specim'
the next morning they will have entirely disappear^-
making this solution the balsam should be first
gently till on dropping a small quantity into wati

V2 nT7\-tlTIfly JJD X0U5TU6

ffTMiivzti:, the tribetaisce more tliazi neeeasaxj. Sections of
tttth aT'^ &=ioagn these, bat thej will be notioed in another
place, ani some insects Caee Dr. Carpenter) when required
to ehow the ramincations of the tracheae.

Having freed the object, then, from these two enemies^
dampness and air — we now proceed to monnt it.

The slide mnst first be cleaned; then on the centre a
quantity of balsam most be placed with a blontlj-pointed
glass rod, according to the size of the object about to be
mounted. To this a slight heat must be applied, which
will cause anj bubbles to rise from the surfiioe of the slide,
so that they may be readily removed with a needle. The
object having been freed from all air by steeping in turpen-
tine, as before described, and then from superfluous liquid
by a short drainage, or touch upon blotting-paper, is to be
carefully laid upon, or where it is practicable thrust tnto,
the balsam just prepared on the slide. In the former
case, or where the balsam has not totally coyered the object,
a small quantity must be taken, warmed, and dropped upon
it, and any bubbles removed by the needle as before. To
cover this, the thin glass must be warmed, and beginning
at one side, allowed to fall upon the balsam, driving a
small *' wave " before it, and thus expelling any babbles
which may remain. This is quite as safely performed (if
not more so) by making a solution of balsam in turpentine
of the consistency of thick varnish or by the use of chloroform
and balsam, as mentioned in Chapter II. The thin glass oover
may bo slightly coated with this, and will then be much
loss liablo to imprison any air, which frequently happens
when the cover is dry. Babbles, however, will sometimes
make tlioir appearance in spite of all care ; but when the
object is comparatively strong, they may be removed by
keeping the slide rather warm, and working the cover, a
little, HO as to press them to one side, when they should be
iui mediately removed with a needle point, otherwise they
arc a^niu drawn under.

Wlicro the slide requires keeping warm for any length of

or MiCKOscoPic OBJECTS. 93

time, a. }ioi-toater hath ia sometimes mado nae of, wliich is
Guaplj B. flat tin, or other metal case, with a, moath at the
ude, that when the hot water is iatrodnced it may he closed
op, and BO retain its warmth for a long time. An escellent
bath may he made of an oriJinary water-plate — coating
al)ont 1b. 9d. Thia may bo filled either with hot water or
Band, and if to it be added a flat tta cover such ae ia naed
in eating-houses, costing about 6i. — a Tery effective OTen.
for baking alidea ia the result. It may he placed on the
hob, or over or near any eonroe of heat. It is easy to add
a thermometer if necessary. In working, tho sHde ia laid
upon it, and so admits of longer operations, when rec[uired,
withont growing cold. Sometimes a spirit-lamp is placed
under it to keep up an equal heat through escessively long
processes. Where the time required, however, is bnt abort,
a thick brasa plate is sometimes used (see Chapter II.),
which may be heated to any degree that is required, the aEde
being previously placed upon it.

Some objects, which are bo thin that they are uanally
Hoated upon the slide, as before stated, require no steeping
in tarpentine or other liquid. These are best mounted by
covering with a little dihiiM halaam, and after this has had
time to penetrate the anbatance, ordinary balsam is laid
npon it, and the slide finished in the usual manner.

I have stated that balsam is usually applied to the slide
and objecte with a blontly -pointed glass rod ; but for the
pnrpoae of drawing the halaam from the bottle, and convey-
ing it to the desired place. Dr. Carpenter nses a glass
syringe with a free opening. These are his instructions : —
"This (the syringe) is most readily filled with balaam, in
the firat instance, by drawing out the piston, and pouring
in balsam previously rendered more liquid by gentle warmth;
and nothing else is required to enable the operator at any
time to eipel precisely the amount of balsam be may require,
than to warm the point of the syringe, if the balsam should
have hardened in it, and to apply a very gentle heat to the
syringe generally, if the piston should not then be readily

Oi PREPAEATIOIf AKD MOrUTISO

pressed down. When a number of balHam objects are being
moDDted at one time, the advantage of this plan in regarct^
to facility and cleanliness (no anperdnoas balsam being'
cleposited on the slide) will make itself aensiblj felt," bat
the collapsible metal capsules are certainlj tbe best and
most easily managed.

When the mounting has been thns for accomplished,
the outer wall of balsam may be roughly removed after a
few hours have elapsed; but great care is necessary lest ^^
the covet be moved or disturbed in any way. In this ^^
state it may be left for the final cleansing nntil the balaam ^^r^a
becomes hard, which tales place aoouer or later, acoordiug "^^^g

td the degree of warmth to which it has been sabjected ^3.

Many advocate baking in a slow oven to accelerate thi^^ -ia
drying; bnt with some objects even this heat woold b^» oe
too great, and generally a mantel-piece, or other plac^^f^ce
about eqnal to it in temperature, is the best suited* ^d
to this purpose ; and when the rcqaisite hardness ii -i: is
attained, the slide may be finished as follows : — With s a

pointed knife the balsam mast be scraped away, taking car -r^c-re
that the thin glass be not cracked by the point getting ^trag
iinder it. If used carefully, the knife will render the slid^Earie
almost clean ; bnt any miunte portions which still adherri^Er are
to the glass must be rubbed with linen dipped in tnrpentiw — ^m e
or spirit. If the balsam is not very hard, these smtL^ ^H
fragments are readily removed by folding a piece of pap^ -^er
tightly in a triangular form with many folds, and dampil^^^^HD^ I
the point with which the glass is rubbed. As the pap
becomes worn with the friction, the balsam will be carri»-
off with it. In some cases I have found this simple e=
pediont very nseful.

Sometimes the object to be mounted is of such a thic:
neas as to require a cell. For this purpose glass rings e
used (as described in Chapter V.), and filled with bals^
The best mode of doing this is thus described by Mr. T- S
Kalph in the Microscopic Joiinial: — "The question vwaa
asked me when I was in England, if I hnevi how to EU a

ECTS. S!)

a lamp of fresli cbalk into pieces not larger than a walnut ;
then) crneh, but not grind, leat jou dtstroy the forma, into
& coarse powi^er that will pass a somewhat wide sieve. Tie
thia, as a pudding, in a, stout piece of calico. Drop into
nater and allow the bundle to become aatorated, and tlien
tnead with the hande. Thia will espel a quantity of milky
water. From time to time, after allowing the fluid to drain
off, the cloth should be untied, acd retied more closely to
the masB ; and when the contents are reduced to about one-
third of their originsl bulk, all large pieces of chalk, portious
of spinea of echini, &c., should be removed, lest tliey injure
the more delicate forma. Care mnat be taken in the
kneading when the greater portion of the chalk has
eacaped, and at last the bag only shaken until the water
fiowB from it almost clear. Tbs whole may then be trans-
ferred to a bottle ot clear water and treatL'd aa before
described. The reaulta, Mr. Bobertson saya, will be aatia-
fikctory, and the chalk must be Tery poor in foasils if 2 lb.
would not aatisfy any microacopic obaerver.

"When the Poraminifera are of a larger aize.thongh trana-
parent enongh to be monnted in balsam, the air must bo
first expelled from the interior, otherwise the objects will be
altogether unsatisfactory. To accomplish this they must
be immersed in turpentine and submitted to the action of
the air-pump. So difficult is it to get rid of this enemy,
that it is often necessary to employ three or four exhans-
tions, leaving Ihem for some time nnder each. When all
air haa given place to the turpentine, they nmst be mounted
in tbe ordinary way.

Of all objects which are commonly met with, few are such
general favourites as the Poltctbtin.e ; and deservedly so.
Their forms are most beantirul, and often peculiar — stars
' varying in design, others closely resembling crowns ; the
a Arielotdls like a croaa, and many whose shapes
1 words could deaeribe. The greater part, perhaps, of
1 those whicb are usoally sold, are from tbe rocky parts of
t Bermuda; but they are aleo found in Sicily, some parts of

163209

Afrits and America. Tfacr are DSamllj- moanted in ba]8«m.
bnt are eqaallj beaatiful moanted drj, and Deed with tha
IreberLnfao. Tbej require as mach care ia cleaning &■ the
CiatoiDacese. but tbe process is a different one, Sametinie*
tbia ia effected by simplj washing nntil thej are freed trom
nil ettraneouB matter ; bat this ia seldom as efiectnal as it
shoaid be. In the Mirratet^ie journal Mr. Farlong givea
tbe following method of treatment as tbe best be knowB : —
Procore—

A large glass Teasel with 3 or 4 qaarta of water.

XeiT tin saucepan holding 1 pint.

2 thio precipitating glasses holding 10 at. eaoh.
Take 3 or., of drj Barbadoes earth (lumps are best), and
brealc into rather Hmall fragments. Put 3 or 4 at. of uom.
lunn washing soda into the tin and half Gil it with water.
Boil strongljr, and having thrown in the earlh, boil it for
half an hour. Poor nine-tenths of this into the large glass
vessel, and gentlj crush the remaining lumps with a soft
brialle brash. Add aoda and water as before, and boil agaia ;
then pour o£r the liqnid ioto tbe large vessel, and repeat
until nothing of value remains, Stir tlie large vessel « '
an ivory spatula, let it stand for three minutes, and pour
gently off nine-tenths of the conteata, when the sheila will be
left, partially freed only, like sand.

2kd FjtocEsa, — Fat common washing foda and water into
the tin as before, and having placed the sheila therein, boil
for an hour. Transfer to tbe large vessel as before, and
after allowiog it to stand for one minute, pour off. Each
washing brings off a kind of '' Hock," nUiub seema to be

3iin Fkocess.— Pot the shells in a precipitating glass
drain off the water nntil not more than ^ oz. remains. Add
half a l^eaapoonful of bicarbonate of soda, dissolve, and then
pour in gently 1 oz.of strong sulpfanria acid. This liberate!
the " flock," etc., and leaves the shells beautifully trans-
parent. Wash well now with water to get rid of all soltl
and other aolable matter.

OF HICBOECOPIC OBJECTS. 101

Some of tbe large ebella are destrojed bj tbia method,
bat none tbat are lit for microacopic uBe. An obliqne light
ebowH theBe 0>ji;cts best.

Tbeae are Bomctimea treated in the manner described in
Chapter III., where the diutome are apoken of, but inaTij
foriDH are Hable to be injured by Ibis severe proceeB.

It baa been before stated that some of tbe znophjtea may
be mOQoted drj, and others eiamioed bs opaque or trana-
parent objrcta accordini; to their anbataDce. They are very
intereatidg when examined in the trongh whilst living, but
to pteaerte many of them for future eiaminiition they must
be mounted in aome preservative medium. Sooietimea thia
may be one of the liquids mentioned in Cliupter Y., but
if possible they sbonld be kept in balsam, as there is leas
danger of iojnry by accident to tbia kind of elide. This
method of mounling presents some difficnlties, but I think
that all agree as to the trnstworthtneas of Dr. Golding
Bird's information on tbe subject, which appeared in tbe
MicToecopie JuunwX. Of this, apace forbids me to give more
than a wmdeneed account, but I hope to omit nothing of
moment to the reader for whom these puj^es are written.

AfUr atating that there are few who are not familiar
with theae exquisite forms, and have nut regretted tbe great
losB of beanty they eostain in drying, he informs ns that
from their ho obstinately retaining air in tbe cells and tubes
when dried, it is hardly practicable to get rid of it ; and they
ftleo shrivel up very seTiooHly in the procees of drying The
following plan, however, he has found almost jaulilesa in
their preparation.

To preserve them with eitended tentacles, they ahoiild
be plunged in cold fresh water, winch kdls them ao quukly
that these are not often retracted.* The epecimena ehould
be preserved in spirit until there is leisure to prepare tbirm ,

• It b»i been stotert thHt the Ijeaf roBthod of killinff Koo|.hjte6 ia t«
drop Bluohol, French bramij, or benao!e into ibe baIi vMrr iu which
they are plHsed ; as ibia will uHuaa do retniutiou uE tentulus if ic be
dang gradually.

102 PREPABATIOX AND MOCNTING

if, however, they have been dried, they should be soaVed ii
cold water for a day or two before being Bubmitted to the
following proccaaee: —

1. After selecting perfect Bpeoimeos of snitsble aizi
roerse them in water heatifd to aboat 120°, nnd place them
under the reoeiver of an air-pnmp. Slowly exhaust the
air, when bubbles will rise and the water appear to be '
state of HCtire ebullition. AfXer a few miautea re-adnit thi
air and again exhaust, repeating the process three or four
tiroea. This will displace the air from most, if not all, of
the class.

2. Bemove the specimens and allow tbem to drain npon
blottiDg-paper for a few Beconds ; then place them in an
earthen vessel fitted with a cover, and preTJouEl; heated to
about 200°. This heat may be easily got by placing the
vessel for a short time in boiling water, wiping it im:
diately before nsing, with a thick cloth. The specimens
then dropped into this, aovered with the lid, and im:
diately placed under the receiver of the air-pump, and
tbe air rapidly exhausted. By this means they are dried
completely, and so quickly that the calls have no time to
wrinkle.

3. In an hoar or two remove them from the air-^
and drop them into a vessel of perfectly transparent cam'
phine. This may be qnite oo'd when the horny, tobuli
polypidoma, as those of the Sertnlarite, are used ; but should
be previonsly heated to 100° when tbe calcareous, cellular
Polyzoa are the objects to be preserved. Ttie vessel should
be covered willi a watch-glass and placed under th
oeiver, the air being exhausted aud re-adiuitted two or three

4. The slide which is to receive the specimen should be
well cleaned and warmed so as to allow tbe balsam to flotv
freely over it. This must be applied in good quantity, and
air-bubbles removed with the needle-point. Take the poly-
pidom from the camphgne, drain it a little, and with the
forceps immerse it fully in the balaam. Tbo glass to be

ECT9. 103

laid npon it should be warmed and its eurfaca covered with
a thin layer of halsam, and then lowered fjradiiallj npon
it, when no babbles sboald be imprisoned, A narrow-
piece of card-board at each end of the object, for the
cover to rest apOD, preventa anj danger of crushing tbo
specimen.

This mode of moonting poljpidoraa, &a., aeeraa to gire
aimoat the complete beauty of tlie fresh specimens. They
are very beautiful ohjeota when viewed wilh common light,
but much more so when the polarizer is used (in the tuauuer
described a little farther on).

To the above inetructioua there can be little to add ; but,
I may here mention that some young stadenta may uot be
posBeeaed of the air-pump, and on this account put aside all
search for those speoimtna which need litlle looking for at
the eeaaide. Many of these, however, though tbey lofe some
beauty by the ordinary mode of drying, will, by steeping for
Bome time in tarpeutine, not only be freed from the air-
bubbles, hot suffer so little contraction that they are a
worthy addition t^ the cabinet.

Another class of objects is the spkula met with in
sponges, &a. These are often g!a,sB-like in appearance and
of various shapes ; many are found resembling needles
(whence their name); some from tbe syn apt a are anchor-
like, wbiUt others are star-litte and of complex and almost
indescribable combinations. As some of these are composed
of silei and are consequently not injured by the nse.of nitric
acid, the animal substance may be removed by boiling them
in it. Those, however, which are calcareous must be treated
with a strong solution of potash instead ; but whiubever
way is used, of course they must afterwards be freed from
every trace of residue by careful washing.

These spicules may be often found amongst the sand
which generally accumnlates at the bottom of tiie jars in
which sponges are kept by those who deal in Ihfm, and
most be picked out wilh a camel-hair pencil. The speci-
mens obtained by this meana mill seldom if ever requite

any cleiLning prociige, as thej are quile free from a
matter.

In tbo former chapttr were noticed ttose insects or parti
of them whii-h are usaally mounted dry. When they are
large and too opaqne to admit of the diy treatment, thej
mast be preserved in Canada balaam or flaid. The first of
these may now be considered.

It may be here mentiooed, that with these objects maeh,
heat must not be employed, as it would in eoaie inatanoea
give rise to a cloodine^a, and almost invariably injure theiir>

In killing the insect it ia neoesHary not to rob or brealt
any part of it. This may be performed by placing it ii
Kmalt box half filled with fragments of fresh laurel-leave^
by immersion in turpentine or strong spirit, as also in boId-
t.ioDB of various poisonous salts. After which it may t
preserved for some time in tnrpentioe or other preservativs;
liquid (Chapter V.) until required. As an assistance to
Ktudent, I believe that I can do no better than give him
plan pursned by my friend Mr. Hepworth, wboeo epecimeoi
are in every nay satihfactory ; but when his method ia useft,
the insects mast not have been jjlaced in turpentine fot
preservation : —

"After destroying the innecta in chloroform or solphnr
ether (methylated being cheaper), wash them thoronghly il
a wide-neciied bottle, hair-filled, with two or three waters;
the delicate ones n quiring great care. Then immerse
in liquid potash (or Brandixh's solution, which ie strong^
than the usual preparation), and let them remain a loDger
«r shorter time according to their texture. When ready to
remove, put one by one into a small saucer of clear water,
and with a camel-hair pencil in each hand press thej
to the bottom, hofding the head and thorax with the leflr
hand brush, and apjilyingprtSKUre with the other from abovei.
downwards, giving the brush a rolling motion, which gene<
rally expels the contents of the abdomen from the thorax.
A minute roller of pith or cork might be used instead of the
brush. In larger objects, use the end of the finger to fiatten

or jtiCBOEconc objects.

105

them. Large objects reqaire more frequent wasliing', aa it ifl
desirable to remote the potash thoroughly, or crystals are
apt to form after mounting. Having placed them on the
Hlidea with thia glass coders, tied down willi thread,* dry
and immerse them in rectified apirits of terpentine ; place
the Teasel under the receiver of an air-pump, and keep it
eihansted until the turpentine has taken the place of tlio
air-hubhiea ; they are then ready for the application of the
balsaai. Larger ohjectB may often with advantage he trans-
ferred to a clean slide, as daring the drying there is con-
aiderahle contraction, and an outline showing this often
remains beyond the margin. When closely corked, tliey may
remain in the spirits two or three months. Aa you take
them from the hottle, wipe as moch turpentine off aa pnasi-
hle before removing the thread, and when untied carefolly
wipe again, placing the finger on one end of the cover whilst
you wipe the other, and vice versa. By this means yon
remove as mnch turpentine from nnder the cover as is
neoessary; then drop the balsam, thinned with chloroform
(aeo Chapter II.}, upon the slide, letting the fluid touch the
cover, when it will be taken in between the surfaces by
capillary attraction ; and after pressing the cover down, it
may be left to dry, or you may hold the sbde over a Bpirit-
lamp for a few seconds before pressing down the cover. If
heat is not applied, they are much longer in drying, hut are
more transparent. If made too hot, the boiling disarranges
the ohjectB, and if carried too far, will leave only the resin of
the baUam, rendering it so brittle that the cover is apt to
By off by a fall or any jar producing sufficient concussion.
Never lift the cover up, if possiljle, daring the operation, as
there is danger of admitting air. A few buiibles may appear
immediately after moon ting,bat they generally subside after a
few hoars, being only the chloroform or turpentine in a state
of Taponr, which becomes condensed."

D the

which «ill HI

106 PatPiBATIOS iKD MOCKTINQ

This metliod of preparing and mouoting inaecta I can
ntroDglj recommeod aa giving Grst-rate rcsulLs ; but n'
the specimpDH are Eioitll, they seldom need tlie soaking in
canatic potash ivhiah larger ones must hare. It ia oulf
Dfcesaary to leave them airhilH ia turpentine, especiallf
when the; have heen first dried nith gentle pressare between
tiro glas^^es. and then mount with balH&m in the ordinarf
way. Witli many, even of the larger iuseatB, by soakin;
them in turpentine or oil of cloves for a longer time, thej-
are made bo much more transparent and even colourleat,
us to exhibit their internal organs (which are visible in
layers, bj the aid of the binocular microsoopp), the mneclea
of the legs, &c. They become also very beautiful objects for
the polariacope.

Amongst the insect tribes there ia abundant employment,
enpecially for the lower powers of the microscope. Bat if
the deeper wonders and beauties of the animal eoonomjp
ere to be songht out and stndied, it ia desirable that thq
various parts should be set separately, in order that thej
may receive a more undivided attention, as wel! as 1:
dered capable of being dealt with under the higher powers^
We will therefore briefly consider the treatment which Dtft
different portions require.

The eyes of butterflies, and indeed of almost all iusectnl
afford materials for a study which ia complete in '
When examined with a tolerably high power, instead i
finding each eye with an nnbruken spherical surface, it il
seen that many are composed of thounnnds of heiagoual
divisions, each being the outer snrface of a separate portiol
termed the ocellus. In others these divisions are sqaarei
but in all there is a layer of dark pigment aurronnding th«
lower parts. The ocelli may be partly removed from th<
eye, which will show how their tapering forms are arranged
But here we have to consider how to place them in baJaait
for preservation. The eye being reruovcd from the inseoli
and the dark pigment removed by the use of a camel-h
pencil, muiit be allowed to remdin in tnrpenline at least tat

F UlCUOSCOPiC OBJECTS.

107

aome daya. The turpentine should then be mnev/ei and
the eje woU washed in it just before it ia to he mounted.
It may then be set in halsam in the sEUiio way as any other
object; — but here a difficolty is mot with. The eye being
spherical upon the aarface required, most necesaarily be
" folded " or brcteii in attemptiug to flatten it. This diffi-
cnlty may be ofttn OTeroome by catting a nainher of slita
ronnd the edges ; bnt some object to this mode of treatment,
and, where it ia practicable, it h much more aatisfactoi'y to
monct one in the natnral ronoded form and another flat.
Instead, however, of mounting the organ whole, foar or five
slides may be procured from each of the larger ones, snob as
those of the dragon-fly, &C,

The anterejHD also are often mounted on. separate slides,
aa being better snited for higher poncrs and more minute
examination than when connected with the insect. These
two projecting organs, issuing from the head, are jolntBd,
and moTi'able at will. They difler very much in form
amongst the varions species, and are well worth the atten-
tion of the microaoopist. They are nsually mounted with
the head attached, and perhaps they ace more interesting
when thus seen. Same few are very opaque ; to prepare
these the following method has been advised, though it ia
I'ar better to view them as opaque objects ; —

Bleach the antenuEo by soaking iu the following solution
for a day or two : —

Hydrochloric acid, 10 drops.

Chlorate of potash, g draohra,

Water, 1 oz.

This will render them tranaparent. Wash well, dry, and
mount in Canada balsam. Instead of the above, a weak
solution of chloride of lime may be used, by which means
the nerves will be well shown. Many, however, are rendered
transparent enough by simply soaking in tarpentine for a
longer or shorter time. Where the antenna;, however, are
"Plumose," or feathec-Hke, estreme care ia required in

moQD ting, though tha difficalty is not so great as so:

to think. If they are first dried with gentle press

then anbjected to the action of the air-pamp in a. emaJL ]

qnantitj of tarpentine until the air is thoroughly expelled,

tbey can be easily finished npon the slide, especially nhen i

balsam and chloroform are used.

Insects Bopply ns trith BDother Beriea of beaotifnl objeot*,
viz., the feet* Theae are BometimeB simply dfied and
moanted nithoat any medium, as before mentioned; bat
most of them are rendered lunch more fit for examination ]
by using balHam in their preserTation, as it greatly ir
thoir transparency. The srnaller tiuds may bo dried with J
gentle presaare betwixt blotting-puper, and then immersed I
for some daya in turpentine, without requiring the treat*
ment nith liquor potasea?. This immersion will render them |
beautifully transparent, when they may be mounted i
balsam, in the nsual manner.

It is, however, sometimes found difficult to fix the feet J
when expanded, in which state the intetcat of the object ia I
greatly increased. Mr. Balph recommends the followiag ]
mode : — " First wash the feet, while the insect ia yet aliv% I
with spirits of wine; then, holding it by a pair of forceps 1
close to the edge of & clean piece of glees, the insect will I
lay hold of the npper surface by its foot; suddenly drop>l
another small piece of glass over it, so as to retain thil foot |
expanded, and cut it off with a pair of scissors, tie r
and soak, to get rid of air." Mr. Hepworth says that he J
never found any difficulty in expanding the loot <
drop of nater or well-wetted slide, and laying a thin glaaa 1
cover over it, tying with tbread, drying, and immersing U
turpentine.

The month, also, with ils organs,
in many insects. That of the con
and is comparatively easy to prepare,
head, the tongue (as it is commonly ten

n interesting object 1
1 fiy is often ui

By pressing the J
ned) will he forced I

to protrode, nhen it must be aecared hy the same meana as
the foot, and maj be subjected to the aoaking in turpentine,
and moanted as usual. The honey-bee is, however, very
different in formation, and Ja well worth another elida;
indeed, even in insects of the same claaa, the differences are
inanj and interesting. There is anothrr good friend to
the MioroBcopic Cabinet, the large water-beetle, " Dytieaa
marginalis" ; and he is by no means nncommon, aa he may
be met with in many old ponds. If his wings are taken,
dried, and mounted in balsam, beautifal circles with crossea
make their appearauoa when examined by the aid of
polarized light. Bat what are commonly termed his
Backers are perhaps, bis most popniar gifts. On bis an-
terior legs will be found small discs attached to central
members (making the whole an exact resemblance of a boy's
BHcker), which may be readily cut off, placed on the slide,
and mounted in balsam. The Dytiaits also gives splendid
eiamplea of spiracles ; but this will be mentioned where
dieaection ia treated of.

Another worthy object of study ia the respiration of
insects, which ia effuoted by tracheeo or hollow tubes, which
generally run through the body in one or more large trunks,
branching ont on every side. These terminate at the sur-
face in openings, which are termed spiraf.y.s, or breathing
organs. The lnic}i-e<E often present the appearance of tubes,
constrncted of a spiral thread, somewhat resembling the
spiral fibres of some plants. These are very beantifnl
objects, and are generally mounted in balsam, for which
reason they are mentioned here ; brft as they evidently
belong to the dissecting portion, they will be fully treated of
in another place.

Amongst the parasitic insects a great variety of micro-
eoopio subjects will be found. Aa these are nsnally small,
they may be killed by immersion in apirita of turpentine;
and, if at all opaqne, may be allowed to remain in the
liqaid nntil tranaparent enough, and then monntnd in
Canada balsam.

110 FBEPAHAIIOS .

The Bcarida, or niAiet and tichs, axe welt known; none;
perhaps, better than those whicli are ao often fonnd npim
cheese. Flour, Bugar, figa, and other eatablea are
iofested hy thera ; whilst the diseases called the itch ii
and the mange in animala, are prodaced bj creataie
belonging to this tribe. These insects areaometimeB m
by simply steeping tham in tnrpentine, and procieding Bl
with other insects. The Micrographic Dictionary gird
the following directiona as to monnting pniis of theBe:-^
"The parts of the month and the legs, apon whioh tb
ohnrHoterB are nsnally founded, may be best made oat h
onishing the animals npon a slide with a thin glass dot
Bnd washing away the einding substance with water : son
times hot solntion of potash is requiaite, with the aobaeqnt
addition of acetic acid, and further washing. When aftet
wards dried and immereed in Canada balea
parts become beautifully distinct, and may bo pertnanontl
preserved,''

Feathers of different kinds of birds are nsnally mounte
in balHsm when required to show mnch of the strnotuni
This is particularly interesting when the feathers are «mBl
as they then show the inner anbstance, or •pith, as it may b
ternted, with the cells, &c. The " pinnro," or soft brancht
of the feathers, will be found of various conatructions ;
possessing hoots along one side, whereby they fasten tfaed
selves to their neighbours; others branching out,
straight points somewhat resembling the hairs from cei
caterpillars. But, of course, when the metallic-lookiu,
gorgeons colonrs are'all that is required to he showi
reflected light nsod (as with the ftathers of the hna
bird, peacock, Slq.), it is mnch better that they should bA
mounted dry, as in Chapter III.

The seeds and pollen of plants are most frequently
mounted dry, as mentioned in Chapter III.; but the mo»
transparent of the former, andthe darker kinds of tbelatteii
are perhaps better seen in Canada balsam. There i
nothing particular to be observed inthemanipulatio.

OF UTCBOSCOPIC OBIICTS. Ill

"that the glass cover mast be applied lightly, otherwise the
grains may be crunhed. There are some objects which
cannot be ehown in a perfect manner when monnted dry,
but when immersed in balsam become so very transparent
that they are almost DeelHSB, To avoid this, it has been re-
commended to stain the objects any coloar that may be con-
venient, and afterwards monnt iu bakam in the ordinary

Permanent djea, however, for these minnte oYjects are
not so readily procurable. My friend Mr. Abbey showed
me that what was permanent with vegetable matter of one
kind waa totally nDlrnatworthy with another. The most
nsefnl that I have tried is Magenta, and the colotir is a
convenient one. Whatever is nfeci for this pnrposo shoold
be in solution, and the object steeped fur awhile aud after-
wards thoroQihlf washed, in order that no superflaons salt
nay remain. Tnere.are many liquids now sold by every
chemist which will help the student in this respect.

Most objects intended for the polariscope may be mounted
in Canada baii-ain ; but there are some exceptions to this.
Many of the salts are soluble in this medium, or their forms
BO injured by it, that glycerine or oil has to be used {see
Chapter V.) : others inuKt be left in the dry form, as before
mentioned; and eoaie few it is impossible to preserve tin-
changed for any length of time. Crystals, however, are
amongst the most beantiful and interesting subjects for
polarization ; and it is very probable that, by the aid of the
polariscope, Dew and valuable facts are yet to bo made
fcoown. For one who Hods pleasure in form and colour,
there is a field here which will ouly open wider upon him as
he advances; aud int^tead of beiog in anywise a merely
mechanical occopation, it rcqaires deep and careful study.
The little here said on the subject will shoiv this in some
degree.

With almost every salt the method of cnjetaUization must
be modified to obtain the beat forms ; I may even go further
than this, and say that it is possible to change tbeee forma

112 ritBrMU-TiON asb uqukukg

to anch a, degree that the eye can perceive no relationahip
to eiiat between them. If a solution of sulphate of ii
made, a Bmall quantity spread evenly upon a slide, and then,
fiufiured to dry whilst in a flat position, the crjstala often
reBemble the fronda of the common fern in B]ia.pe. Bat if^
whilst the liquid is evaporating, it ia kept in motion hj
stirring with a, thin glaas rod. the crystals form separately^
each rhombic piisni having ita angles well defined, and.
giving beantifol cnlonra with the polarized light, Agai:
pyro-gallic acid, when allowed to flow evenly over the alid«i
in a saturated solution, covers the aurface in long needle^
which are richly coloured by polarized light; but if any
Bmall portion of dnst or other mutter should form a nnclens
aroand which theae needlea may gather, the beauty i
wonderfully increased. A form very closely resembling th»
" eye " of the peacock's tail, both m form and colour, is then
produced, which to one uninitiated in crystallography bear*
very little resemblance to the original crystal. From theaa.
aimple facts it will be clearly seen that in this, as in every '
other department, study and experience are needful to gin
the best results.

Sy dropping a saturated solution of any aalt into alcoh<A!
— where it is not soluble in the alcohol — crystals i
stantaneoDsly produced, and the results are often very ourioo^
and beantifnl. These crystals can easily be taken np bj K
pipette — deposited upon a slide, and, after having been
allowed to dry spontaneously — mounted in balsam.

To obtain anything liko uniformity in the formation of
crystals upon the glass slide, every trace of grease must be
removed by cleaning with liquor potassae or ammonite ii
mediately before using, care also being taken that none
the agent is left upon the slide, otherwise it may i
terrupt and obauge their relative position, and even thelt
form.

Amongst those which are generally esteemed the most
beautiful, are the crystals of ozalurate of ammonia. Tbfl
preparation of this salt froca uric acid and ammonia ia

ECTS. 113

rather difficult procesp, nnd will not, on that acconnt.lje do-
scribed here; bnfc when poesegaed, a small qaaotity of a
strong solution in watar must he made, and a little placed
a the slide, and evaporated elowlj. Part of the salt will
then be deposited in circles with the needle-like crystals
eitending from common centres. They Hhoold then be
monnted in pare Canada balsam ; and, when the beet coloors
are wanted, nsed with the eeli'nite plate. Of this cIbbb of
crystal, salicine is a aniver^al favourite, and can he easily
procured of most chemists. The crystals may he produced
'n two ways ; — A small portion of the salt niust be placed
upon the slide, and a strong heat applied underneath nntil
fusion ensues ; the matter should then be evenly and thinly
spread over the surface. In a short time the crystals will
form, and are generally larger than those procured bj the
following process ; but the uncertainty is increased a little
when fusion is used, which, bowever, is desirable with many
Bait?. Secondly, make a saturated solution of salicioe,
vhich is effected by boiling one part of the salt in eigLteen
of water, and allowing it to cool. Place a little upon the
slide, and let it evaporate spontaneonHly, or with the aid of
gentle heat. The crystals are generally uniform, and with
ordinary powers quite large enough to make a beautiful
object. Their circular shape and gorgeous colours — ^even
without a selenite plate — have made them such great
favonrites that there are few cabinets without thtm.

There are also some salts which are crystallized in a some-
what different manner from those before mentioned. San-
lonine ie one of the most beautiful, snd will illustrate my
meaning. Place a small portion upon a slide, and heat over
a lamp nntil it is fused. With a hot needle spread the salt
over the surface required. As the slide cools, the formation
of crystals tak^ place, nntil it becomes one mass. This
Bait ia slightly soluble in the ordinary balsam, end should
be mounted in castor oil. If, however, the slide is well
eovered under the thin glass, the balsam soon becomeB
saturated, and very little injury results. According to the

114 PKEPAKATIOS ANll MOUNTING

temperalure daring crjetallizatioa the character of th»
crystals is affected. If the fused kbII is very hut, the crjataU.
run in straight Ilucb from a oommon csotre. If tba heat il
(irhat I roaj term) medium, the crystals show ODDoentria
waves of verj decided form. IF the slide is conl, the crfstals,
still concentric, are oiceedingly minate. The most beautiful
crystals for the niicroBcopist are thoBB formed at a tern-
pcratare betwiit the second and third above mentioned, t
the minote and wavy forms are thea combioed, and 1od{(,
feathery crystals are the rosnlt. Aa this method reqairei,
some little practice, many crystallize the salt in a simplet
manner, which I will give ; but the variations obtainable*
by fusion give that mode the precedence. Dissolve a fevi
grains of suntonine in a drachm of chloroform, and drop the
Eolotion npon a glass slide. Allow the liquid to evaporat^,
and beaatil'ul crystals will be the resnlt. Mount as above.

In fear of being somewhat uninteresting to part of my
readers, T feel aa tbongh I should not be fulfilling my desire,
of giving every information, if I omitted to show another
method of crystallisation, which a novice would cast awa^
88 a failure before he had completed hia eqjeriment. Tartrate
of soda, made by neutralizing a strong solution of tartario
acid by the addition of carbonate of soda, is spread in so1n«
tion over a glass slide, and must be then warmed, but not
lioilad. It must now be laid in a dry place, protected from.
all chance of dnst. In time — from one or two days to a
many weeks — Bome of the slides will prove beautiful objeots,,
showing the cross form surrounded by rajs, Someof thes
slides never crystallize, thongh I can lind no reason for this,,
and even the application of heat to these calls out no decided.

Hippuric acid will be found moat interesting to those who
are fond of beautiful polariscopio effects, inasmncU a
salt is capable of giving an afitounding variety in the forms
of its crystals. Make a saturated solution in absolote
aicohol, and use it warm; by dropping a small quantity
irou] a warm pipette on to a warm slide a film will spread

OP MICROSCOPIC OBJECTS. 115

IT tbe slido and orystala of a. oircnlar form will licgin to
jear, and may be modified by the atmosphere in which
they are allowed to grow ; tbua a moiat atmoaphere oi the
e?erse, an atmosphere of vapour of ammonia, apirit, ben^tole,
c aulphureous famea, will eaah prodnce a different resnlt,
and the modifications thos produced will afford food for very
Mrioaa reflection on the changes one aalt maj ba made to
'n contact with other agents. These crystals are
■faest mounted in castor oil — hnlaam that is very liqnid —
tiot balsam in baiKiole, as tbe henzole changea the character
of the crystal.

Many new forms may he procured by nniting two totally
differeat salts in solation in certain proportions. This ia a
field affording new facts and beaaties ; but requires some
chemioal knowledge and much perseTeraoce to obtain very
valoable results. Ooe of the most beautiful I have met
with baa been composed of sulphate of copper and aalphate
of magnesia. The flower-like forma and uniformity of
cryatallizatios wlien Buccosfifiil mnko it well worth a few
a at first ; and as I became acquainted with some new
facts in my freqnent trials, I will give the preparation of the
double salt from the begioniog.

Make a saturated solution of the two sulphates, combined
a the proportion of three parts copper to one part mag-
nesia, and then add to the solution one-tenth of pure water.
.ITo dnat or other impurities should have access to the slide,
Bud it should be freed from all traces of grease by cleaniuf;
'mmediately before use with liquor potassffl or ammouirB. A
drop of the solation should then be placed upon it, and by
a thin glass rod spread evenly upon the surface. Heat
this whilst in a horizontal position until the aalt remains as
e transparent substance, which will not be effected
until it ifi raised to a high degree. The slide may now be
allowed to cool, and when this ia accomplished, tbe flower-
like crystals will be perceived forming here and there upon
the plate. When these are at an; stage in which it is
wished to preserve tliem, a few seconds' exposure to the fire.

118 ruEriHiTioN and modntikg

cooliing, the Boales may be easily taken froi
Bnrface. Tbey maat then be waabed and tborongblj
cleaned. After drying, eoak for a day in tar]>entine,
monnt in the ordinary manner with balsam. This
good polarizing object ; but the intereat, and I think thi
beauty, is inoreaaed by procuring a piece of eel'a skin with
the scales in silu, waahing and drying ttnder preaenre, s
monnting in balsam as before. The arrangement of i
BcaleB produces beaatiful " waves " of colour, whioU i
quite soothing to the eye after eiamining some of tbe vi
gorgeons eaJta.

Tiiere are many scales of fish which are good fiubjeets
the polariscope when moanted in balsam ; but as they
qoire no particular trodtment, they need

Among haira we find some wbicb are beantifnl nhel
monnted in balsam and examined by polarized light. Sam^
when wanted as common objects, are always nsed dry, a
bcfure mentioned ; but if they are intended to be shov
jiolarjzing objects, they most be placed in some medino.
The Micrographic Bictionary mentions a mode of makini
an interesting object by plaiting two aeries of white
hairs at an angle, mounting in balsam, and nsing with ttU
polariscope. All haira, however, mast be steeped i
pentine for a short time before mounting, as they will thqB'
be rendered cleaner and more transparent. When this ii
done, there is no difficulty in mounting them.

Many of the "tongues" of fresh-water and
mollosca are deeply interesting and most beaiitifol objefl
when examined by polarized light. As these are nsaallj
mounted in balsam, I mention them in this place; '
they must be removed from tbe animals by dissection,
particnlars respecting them will not be entered into i
we come lo the part in which that operation ia deacribact
(Chapter Vf.).

The manner of preparing and moanticg many of thM
f olyzoa and Zoophytes has been before described ; but atg

OJf MICROSCOPIC OBJECTS,

notice of polariainff objecta would be incomplete wilhoot
BomB allnaion to them. A small jiieoe t^f the Flutitra
oviculaTis, well prepured, ia beautiful when examinoJ in
thia manner. No Helenite ia needed, and jet the coloura
are truly gorgeoas. It ia often met witli upon shells and
zoophjtea of a larj^e size, and will well repay the trouble
of Bearching for. Many of the Sertularidio are very beau-
tiful with polarized light, and, indeeJ, no ramble upon the
seaaide need be fruitless in this direction.

The different s(ui'c?ics are quite a study in themielvea,
and are peculiarly connected with polarized light. Thoy
are found in the cellular tisane of almost every plant in
amall white grains, which vary considerably in size; that
from the potato averages one- three- hundredth of an inch in
diameter, and that from arrow-root about one-aii-hundredth.
To procure starch from any plant, the texture must first be
broken up or ground conreely ; the mass of matter muHt be
then well washed in gently-flowing water, and, as all starch
is totally insoluble in cold water, the grains are curried off
by the cnrrent and deposited where this is stayed. In pro-
coring it from the potato, as well as many other vegetableF,
it is hot necessary to reduce the substance to a coarse pulp
by the aid of a culinary grater ; the pulp should then be
well agitated in water, and allowed to rest a short time,
when the (.tarch will be fonod at the bottom, its lighter
colour reodering it easily distinguish able from the pulp. It
should, however, be washed through two or three waters to
render it perfectly clean.

These grains have no crystalline strncture, but present a
Tery peculiar appearance when eiamincd with polarized
light. Each grain shows a dark cross whose lines meet at
the point where it was attached to tbe plant, called the
hllnm. Round the grain also a series of tines is seen, ae
thoDgb it were pot together in plates. This ia more die-
tinctly visible in some binds than othere.

As to the mounting of these starches there is little to be
said. If the grains are kid Dpon the slide, and as (jidbII a

120 PREriRATION A

portion as possible of the balsam dilnted with tnrpentine,
as before mentioned, be applied, they will cling to the glass
and el11ou7 the pnre balsam to How readily over them with-
cint being bo liable to imprison air-bubbles when the thia |
glass is put upon them.

The raphides, which were fully described in Chapter in., '
when required for use with polariied light, must be monnted |
in balsam, and many are fonnd which gire beautiful coloi:
They require no peculiar treatment, but must be washttd ']
quite clean before putting np. But in order to onderatand \
anything of the natural arrangement of mplddee,
necessary to mount certain parts of plants with these olijecta I
in bIIu. The most common is the coating of the onion,
which moBt be soaited aouie time in tnrpentine or benzole,
in order to render it transparent, and must then be moiinted 1
in balsam, as before said. We abflll then be able to oblaia I
such colours by the aid of polarized light, that the rapliides
are shown in wonderful distinctness, and somewhat of their j
natnre will be perceived.

There is one class of objects for the polariscope whioli 1
diSers in preparation from any we have yet considered, and j
affords very beautiful specimens. Same of the plants, in- 1
eluding many of the grasses and the Eqnisetacece [i.e. hoise- .1
tails), contain so large a qnantity of silica, that when the J
vegetable and other perishable parts are removed, a sVeleton I
of wonderfnl perfection remains. This slieleton must bs J
monnted in balsam, the method of performing which v
now be considered.

Sometimes the cuticle of the equlsetnm is removed from ]
the plant, others dry the stem under pressure, whilst tha I
grasses, of con rse, require no aucb preparation. They should ]
then be immersed in strong nitric acid and boiled for a ]
short time ; an effervescence will go on as the organio matter j
is decomposed, and when this has ceased, more acid should I
be added. At thia point the modes of treatment diSer;.]
Borne remove the object from the acid and wash, and having J

OF MICEOSCOnC OBJECTS, 121

dried, burn it npon thin glaea until all appeara mhite, when
it mnst bi> carefully mounted in balsam. I think, however,
it ia better to Jeaye it in strong acid until all tlie Bubatanoe,
except the required portion, ia removed; but this will take
a length of time, varjio^ according to the mass of the
plant. Of course, when tbia latter method ia need, the
akeleton most be washed from the acid, &c., before being
mounted in balaaro.

Theae sitkeoua ctttides are readily found. The straws of
most of the cereals, wheat, oat, &c. ; the hiiska, alao, of Bome
of theae ; many canes ; the equiaetnm, as before described ;
and some of the graases. Muny of theae are everywhere
procurable, so that the atudent can never want material fur
& splendid object for the polariacope.

In Chapter III. the scales (or baira) which are often fonnd
upon the leaves of plants were mentioned as beautiful olijects
when mounted dry; bat some of theae when detached from
the leaf — which is easily done by gently scraping it, when
dried, with a kiiife — present brilliant starlike and other
forma, if mounted in bataam and used nilh the polariscope.
There is a little danger, when placing the thin glass upon
the balaam, of forcing out the scalea in the wave of matter
which ia always ejected; this may be overcome by applying
to the elide, previously to placing the objects upon it, aa
extremely thta coveriag of balsam diluted with turpentine
as before mentioned, letting it dry more or leas with the
objects placed in it, and then, after the addition of a little
more balaam, putting the cover on, and thus giving tbeoi
every chance of adherence ; or by uaing the balsam with
chloroform, as before noticed. This method is peoaliarly
Buc<iessful in cases where it is desired to arrange several
objects symmetrically on a slide, and to obviate their sub-
Beqoent diaturbance by placing the cover on. Tjpe slides
with several parts of an insect diaplayed upon them, sealea
of fiah, or of plants, &o., way thus be shown, eo that the
numier of elides may by this plan be seriouely diminished.

122 PflEPi.BATIQN AND MOUNTING

These scales are much more abandant than was formerly
snpposed, and new specimens are discovered daily; so that
the Btudent shonld always be on the look-oat for them in
his researches in the vegetable world.

Most classes of objects, and the treatment they require
when monntiog them in balsam, have now been considered.
The next chapter will be devoted to preservative liquids,
and the best method of nsing them.

F MicaoscoPic OBJECTS,

CHAPTEE V.

ATITE LIqBlI

I' WHEBB CELLS

TirzRB are many objecta wliicli woa1d lose all their distinc-
tive peonliarities if allowed to become dry, e9]>ecially those
belonging to the fresh-irater Aigai, many animal tissaes,
and moat of ths very delicate Bnimal and vegetable sub-
Btances in wbich structure is to be sbown. These must be
preserved by immersion in some flnid ; but it is evident that
tbe fluid must be saited to the liind of matter nhich it is
intended to preserve. Aa it often requires ranch study and
trouble to obtain microscopic objects of this class, it is well
that their 'preamtation should be rendered as perfect aa
possible ; arid for this reason the cells, or receptacles of the
fluids, should be ao closed that all possibility of escape
should be prevented. The acconfiplisbment of this is not so
easy a matter as it might appear to tbe inexperienced.

Before giving any directions as to the manipulation
required in mounting the objects, wo must consider the
difierent liquids and cdia which are requisite for their pre-
servation. Of the former there are a great nnmber, of which
the principal way be mentioned.

Distilled Water is strongly recommended by many for
Diatomacere and other Protopbytes. It has been, however,
atated that confervold growths cften disturb the clearness
of tbe liquid, and on this acoonnt various additions are made
to it. A Jump of camphor is often left in the bottle, so that
the water may dissolve aa much as poBBible. One grain of
bay salt and one of alum are added to each onnce of water;
or a drop or two of creosote shnlien up with an ounce of
water, which should be afterwards filtered. These additiooa

121" TREPARATION AND MOUNTING

are often made; perhaps each of them good for certain
objects.

Glycerine. — Some affirm this to be one of the best pre-
servative liquids, especially for vegetable objects ; bat others
think that it is much better when diluted with two parts of
camphor-water, prepared as above.* Mr. A. E. Yerrill, of
Yale College, U.S., says glycerine preserves the natural
colours of marine animals ; and the only pr^ecaution to be
taken is to use very heavy glycerine, and to keep up the
strength by transferring the specimens to new as soon as
they have given out water enough to weaken it much, re-
peating the transfer till all the water is removed before
finally mounting on the slide.

Glycerixe and Gum. — This is also believed to be a very
good liquid for vegetable tissues, and is thus prepared : —

Pure gum-arabic... 1 oz.

Glycerine 1 „

Water (distilled)... 1 „

Arsenious acid ... 1^ grain.
Dissolve the arsenious acid in the cold water, then the gum,
add the glycerine, and mix without bubbles.

Dr. Carpenter states that the proportions used ultimately
by the late Mr. Farrants are : —

Picked gum-arabic ... 4 parts by weight.
Distilled water (cold).. 4 „
Glycerine 2

Thus he now omits the arsenious acid, but places in the
solution (which should be kept in a bottle with glass stop-

* Dr. Carpenter says : — "Glycerine has a solvent power for carbo-
nate of lime, and should not be employed when the object contains
any calcareous structure. In ignorance of this fact, the author (Dr.
C.) employed glycerine to preserve a number of remarkably fine speci-
mens of the pentacrinoid larva of the Comatula, whose colours he was
anxious to retain ; and was extremely vexed to find, when about to
mount them, that their calcareous skeletons had so entirely disap-
peared, that the specimens were completely ruined."

99 it

OF jJicEosconc

I per) a amall piece of camphor. This requires no cell, as the
adheBive power is aufficient.

Dbakk's Compound, — This is uaiially deemed al>out the
best medium for preserving Algie, mnsaec, Ac, and ia thos
prepared ; — Soak 1 oz. of best gelatine ia 4 oz. of water
until the gelatine becomes soft, when 5 oz. of honej hented
to boiling point are added i boil the mixture, and whea it
hae cooled, but not enongh to become stiff, add g oz. recti-
fied spirit with which 5 or 6 drops of creoaote have been
well miied, and filter the whole through, fine flannel. Thia

mpound when cold forms a at iff j el ij, the use of which
will be described elsewhere.

Glvcekinb Jellv. — This miitnre closelj resembles the
ftbove, but aa the composition differs a. little it may be men-
tioned here. It ia atrongly reoommeinled by Mr. Lawrance
the MicroBctipic JouTnal, where he states " tliat the
beantiful green of some mosBes mounted two years ago, is still
as fresh as on the day they were gathered ;" and that thia
ia the only mediam he bDows which will preserve the natoral
colonr of vegetable aobetaoces. He takes a quantity of
Nelson's gelatine, soaks it for two or three hours in cold
water, poura off the supcrflaous water, and heats the soaked
gelatine until melted. To each fluid ounce of the gelatine,
tehilet it ia fluid hut cool, he adds a fluid drachm of the
vrhite of an egg. He then boila tliis until the albumen
coagulates and the gelatine is quite clear, when it is to be
filtered througKfine flannel, and to each ounce of the clari-
fied solution add 6 drachms of a, mixture composed one part
of glycerine to two parts of camphor- water.

At. the Academy of Natural Sciences of Philadelphia,
Mr. W. H. "Walmaley stated, that, owing to the beat of that
climate, the above formula for glycerine jelly was sot satis-
factory, and recommended the. following : — Take one pack-
age of Cos's gelatine, wash repeatedly in cold water; allow
it to soak in water sufKoient to cover it for an hour or two,
add one pint of boiling water, and boil ten or fifteen
minutes. Bemove, and when cool but alill fluid, add the

i the

l-^S PltErAUiTIOS AND MOUNTING

nhite of an egg, vrell boaten, and agaiu boil, until the albu-
men coegutatea. Strain TChilst bot tbrougli flaoDel, and
add nil equal imrtion by meaBurement of Bowyer'B pnre
glycerine, and fifty drops of carbolic acid in Bolnlion; boil
again for ten or iifteen minatee, and again Btrnin through
flannel, place in a wat«r-bath and evaporate to about one-
half, thcQ filter into two or more broad- mo othed vials, (Cotton
IB the beat filtering msdium.) The use of thia in mounting
is the same na Mr. Lawrance'e, elsewhere described.

GoiDBi's Fluid. — This is much naed in the preservation
of animal objects ; and seldom, if ever, acts upon the colours.-
It ia thns prepared :— Bay salt, 4 ox. ; alum, 2 oz.; con "
eablimate, i grains. Uisaolve these in two quarts of boiling
water, end filter. For delicate preparations eonie recom-
mend that this mixture be reduced by the addition of an
equal quantity of water; hut where there ia hone or shell ia
the ohjfct, the above acts injurioualy upon it, in which casa
this fiuid may be used: — Bay salt, 8 oz. ; corrosive auhli-
mate, 2 grains ; water, 1 quart.

Thwaiteb's Liquid. — This ia recommended for the preeer-.
vation of Algm, &a., as having little or no action oi
colour, and ia thua prepared ;— Take one part of rectified
spirit, add drops of creosote enough to saturate it; to thii.
add sixteen parta of distilled water and a little prepared'
chalk, and filter. When filtered, mix with an equal quantity
of eamphor-water (as before mentioned), and strain throogh.
fine muslin before using.

Chloride of Zinc SoLniON. — In the Micrographic Dic-
tionary thia ia stated to be " perhaps the beat preaervativfti
known for animal tisanes." Persons of great experienoa,
however, have given a very different opinion; but it U
tainly very useful in many cases where a small degi
coagulating action is not injuriou;!. It is used of etrengthi
varying according to the softness of the parts to be pre-
served ; the average being 20 grains of the fused chloride to
1 oz, of distilled water. To keep thia liquid, a lump uf
phor may bo left floating ia the bottle. I have heard

lainta that tbia Tnixtura bccomea turbid with keeping; b'lt
thio^ thia must onlj be tlie case v/hea eome impiirilj lia^
g;ot into the bottli;.

Cmibolic Acid.* — The addition of a fow dropa of thia to
distilled water prevoats the growth of interferiog' subatancoa
iwhioh woold take place if pure water alone were used, aai
IB therefore valuable as a preaervative fluid. The same
tolntion also ia coDvenient, aa it iuatautly kilja iufaaoria, and
lilinoat everything that haa life; and, iodeed, is nseful in
tJie atndeut'a gathering-bottles for the same reason. It ia
»ery highly apobea of aa forming one of the coustituenta in
following formula for use in mounting aoft animal
jMtnrea ; —

Araenious acid, 20 parta,
CryfitalliKed carbolic acid, 10 parta.
Alcohol, 300 parta.
Distilled water, "00 parts.

The Rav. "W. W. Spicer, in his tranalation of Johami
Kave'e work on Atgie. recommpiida the following fluid for
their preaervation : — Pnre alcohol, 3 parts ; distilled water,
S parta i glycerine, 1 part. If the deamid or other alga
fee placed in this fluid in a cell, and not covered by a glaas
time, the water and alcohol will evaporate slowly, and
the mixture wiU become more dense in proportion, hot quite
'gradaally, and therefore without any destriictife influence
on the object. During this operation, water is withdrawn
from the frnatule, a.ud the glycerine, which ia not volatile,
takes its place without causing any distortion of the abject.

Castor Oil.— Thia is a very useful preservative for
Ctystals and other objects. Many salts are quite destroyed
when Oauada balsam ia uaed with them; but very few are
acted upon by this oil. To use it, it must be dropped in
AufScieut quantity to coTer the crystal or objt'ct to bo

Ctroo Calvert stated at a. meoting of the British AaaooiatioD,
that af Mr oaroful expariiuenta he finds oarbulio biid " prorenta tlia
" LYelopmaot of protoplaamiu and fungoid lifB."

128 rEErjEiTios and uocktiss

presevTeJ wilh a. thin coating of oil. It may be neoeaaafy
Bometimes to spread it with a needle or other inBtrnment,
The thin glass shonld Ihcn be carefnllj placed upon it, W
thitt all air may be excluded ; and shoald aiDj oil be foiitA
oat, owing to the quantitj used being too great, it mai '
be remOTsJ with blotting-paper. When the edge of tl
thin glass cover and tbe enrrouBding parte of the elidfl a:
as clean as possible, a coating of Bealiog-waz varnish (
liqnid glue most be applied and allowed to dry. A eeooni
or even a third coating may be required, but not before tli
previous cover is quite dry. These varnishes, however, a
very brittle, and it is much safer, as a fiuish, to nse one
the tougher cements — gold-size, for instance — which w
reader it doubly secure.

Tbe above are the principal liquids. &o., used for pre
eerving objects in cells. The different cells may be h
mentioned ; and it is recommended that these should alwayi
be kept some time before oBe in order that the ceniei
become perfectly dry; and care mast be taken that n
cement be need on wbich the preservative liquid employo
has any action whatever.

Cehest Cblis.^ Where the object is not very thick, tl
kind of cell is generally used. They are easily made vri
the turntable before described ; but when the objeets to ti
preserved are very minute, these cells need not be t
deeper than the ordinary circle of cement on tbe siicil
When, however, a comparatively great depth is required, i
is sometimes necessary to make the wall of the cell as de^
as possible, then allow it to dry and make another additiol
Of these cements gold-size is one of the most truatwortlfl
and may be readily used for the shallow cells. The
phaltum and india-rubber, before noticed, I have fonod vi
durable when well baked, and exceedingly pleasant to wi
witb. It may be used of such a thickness as to give spu
for tolerably large objects. Black japan also ie tanch a
Many cements, however, which are recomniended by bi
ivriterB, are worse than oselesa, owing to the brittkness wl

ECis. 129

anSera their durability uncertain, a,s eeaJing-wai, vamiah,
liqnid-glae, &c. Dr. BaHliau says the best cement for liquid
cells is one, much used in Germany, made by adding a.
considerable qaantitj of nitrate of bisuiuth to a solutiou ot
gam mastic in chloroform. It can bo procured at almost
any optioiao'a.

The Btndent may feel himself at a Ions in choofing the
'Cement which will give him. the soj'tsl cells, many of them
becoming partially or wholly dry in a year or two. aa stated
in another place. I can only give him a few general direc-
iiona, and he muat then uae his own jadgment. Of coar^o
it would be lost labour to employ any cement upon which
the prCBeryntiTe liquid has aiiy adiuri KhaUum: It ia alao
a good rule to avoid thoae in nhoae compoaition there arc
MDJ particles wliich do not become a thorough and intimate
.portion, as thesa nnreduced fragments will almost certainly,
«oODer or later, prepare a road by which the liqaid will
jssoape ; and, lastly, whatever oemeut he uses, the cdla are

KIwaye better when they have been kept a short time before

GoTTA-FEBCJTi R[KGS have been recommended by some,
«B affording every facility for the manufactnte of cells for
liqaida i bnt they cannot be reoominended, aa, after a certain
length of time, they become ao brittle as to afford no safe-
guard against ordinary acuidenta. Some have also used
india-rubber baada thickly coated with various varnishea ;
Ijnt theao I consider leas trust-worthy than gatta-
Jiercha, aa they become tlioroughly rotten in ordinary
oae after a short probation,

Olten the cells must necessarily be of a large size, and
Sot this reason are made by taking four strips of glass of the
thicknesa and depth required, and gribding the places where
these are to meet with emery, so as to form a slightly
roughened but Sat edge. The glass atrip must also be
ground DU the side where it meets the plate, and each piece
cemented with the marine-glue mentioned in Chapter II in
the following manner ;— On that part of the glass lo which

PBEPAaiTIOK i

another piece U to bo attached shoTild be laid thin strip ot
tbe glue ; both pieces mnat thea be heAted upon a enlU
brass table, witb the aid of the spirit-lamp, until the etripa
become melted ; tbe small piece is then to be taken ap isi
placed upon the epot to trhich it is to be attached, and H
on nntil the cell is completed. It will be found necessHrf to
spread the glue over the anrface required with a needle or
some other in str am eut, 00 that an nnbroken line majbt
preaeoted to the wall of the ceil, and no bobbles hmA
Too gveat a heat will burn the marine-glue, and render it
brittle ; care must be therefore taken to avoid this.

When shallow cells are required, those which are mad*
by grinding a concavity in the middle of an ordinary slii*
will be found very convenient. The concavities aieoutbora
circular and oblong ; and the surface being flat, the ot
easily fastened upon it. These are now cheap, and ar
safe as to leakage. It is a very great improvement,
it can be done, to turn a shallow ring outside the ooncaritf
of the slide, but close to it. This prevents the cemei
■which the cover is fastened from running in.

Circular cells with a flat bottom used to be made If
drilling a hole through glass of the required thtckneas, <M
flxing this npou an ordinary slide with marine-glae; ^^
the danger of breakage and the labour were so great thri^
this method is seldom used now, and, indeed, the rings
to be mentioned do away with all necessity lor it.

Glass Eings. — Where any depth is required, no methflS
of making a cell for liquids is so convenient as the nae (£
glaaa rings, which are now easily and cheaply proonraUt
They are made of almost every size and depth, and, ejusp
in very eitraordinary cases, the neeessitj for building
is completely obviated. These rings have both edges
rough, and consequently adhere very well to the slide,
adherence being generally accomplished by the aii
marine-glue, as before noticed with the glass cells. Gol3*
size has been occasionally used for this purpose; and WW
adherence, even with liquid in the cell, I have alwaye {oaoi

OF MtCIlOSCOPlC OWBCIS.

131

to be perfect. This method has the advantage of requiring
no heat, bat the gold-size mnat be perfectij dry, and the
ring mast have been liied apon tlie shde Bome time before
nae. Canada baUara has also been naed for the same
porpoae, but cannot be recommended, as, when it ia perfectly
dry, it becomes eo brittle as to bear no shock to which the
slide may be ordinarily exposed.

Iron Ersos.^ — Many have worked with these, having
taken care to varnish thoroughly bel'ore using with any
preservative liquid ; bat they are always untruatworthy, as
they can never be guaranteed against the action of some salt
ID the liquid used. They can be procured beautifully made,
and for dnj cells cannot be surpassed. Zinc and pure tin
rings may alao be procured, and are eicellent, especially Iba
latter,

YcLCisiTE. — Thifl Bubatanco is a great favourite with
Borne of our working raicroaoopiste, aa it is very slightly in-
flaenced by change of temperature. But my owa opiaion ia
that a glass cell ia the safest and most satisfautory re-
ceptacle for any object in liquid, and if carefully prepared
will not deceive the operator.

Theae are the cells which are mostly need in this branch
of microaaopic mounting. The mode of using them, and the
different treatment wbioh certain objecta require when in-
tended to be preserved in the before- mentioned liquids, may
now be inquired into.

I may mention, however, that thia class of objects is
looted upon by many with great mistrust, owing to the
'danger there is of bubbles arising in the cells after the
mounting has been completed, even for years. I know some
excellent microscopists who exclude all objects in cells and
preservative liquids from their cabinets, because they say
that eventually almost all become dry and worthless; and
is no matter of surprise, for many of them do really
become so. Purbaps this is owing to the slides being sold
before they could possibly be tboronghly dry. As to the
air-babbles, I shall have something to say presently.

ir« wa Mv ■ifiiii «»

kr pUiK * eh* liiv ^« tk. riidt Wu ■

Ikv ^taM vUck is la «Bmr a, I tnM witlt « d
ptBtfl * tiag flf gaU-M^ ■■! kbo anond tlie edge Of fl
«dl la Bhick ft M to ■bcR^ Dr. CtarpcBtcr objeeta lo Hal,
m i M JaJ w g tk bi« f p licatin M oT Ura gdd-nse liaUa t(
■*m IB.' A8 diagir af 1U^ bowenr, u MnnjtletelT oh--
visted hf JMiiog tfce AAe aad eoFer for awhile nn^ Um
ctf t bewea fsctUlj' fised, bat still adhesive enimglL
to peHbrw its baetioa (Chapter III.). With many sltdM
tUi it aot mttnmfSAri ia lea tbaa twealj-foar boors, evei
if left two or tkm daj« bo tnjaiy whaterer eaeaeB; ba
with other ktoda bb boor ia too long to 1«are Use
cement, co tbst tbe openttv must use hia own di
It is not alwaja necessuj to aiie tbe edge of the cover
■ince pCTftct adhfeian mtj in maoj cases be seexsied witb
oat it. and it is always beat to use tbe leaat qaantitj d
eement tbat will answer, as it will then be less likely to n
in. The liquid reqaited ma; be drawn up b; the men
into tbe pointed tube neDtioDed in Chapter II., and th
transferred to tbe cell. In the Tarions booba of instructioB
tbe oliject ia now to be placed in tbe cell ; this, howi
think a great mistake, as another process is abBoIatel
oeceBsary before we adviince so far. The cell, full of liqnii
mnat he placed ooder the rsceirer of an air-pump, and th
air withdraon. Almost immediately it will he perceive*
that the bottom and sides of the celt are covered with mionttf
bnhblee, which are formed by the air that is held ii
pension by the liquid. The slide may now he removed, ancl
the bubhleB may require the aid of a needle or other
to displace them, so ohatinately do they adhere t
surface of the glass. This process may then be repeatedr
and one canse, at leaaf, of the appearance of hubbies in oeHs
of liquid will be removed. The object to he mounted ahooH
alio he soaked in one or two changea of the preservativfl
liqnld omplojed, ond, during the aoakbg, he placed under

OF MicKOscoric OBJECTS. 133

tlie air-pamp and exhansted. It may then be transferred
to the cell, aad nill probably cansB the liqaid to averflov a
little. Tbe cover with the golJ-aize applied to the edge
taoBt then be careFitUj laid upon the cell, and sligbtlj
presaed down, ho that all air-bubblesmay be displaced. The
two portions of gold-eize irill now be found to adhere
nherever tbe liquid does not remain, althongb the whole
ring may have been pre»ionsly wet. The outer edge of tbe
thin gUsB and cell must now be perfectly dried, and a
coating of gold-size applied. When thia is dry, the procesa
mnet be repeated nntil tbe cemeot baa body enough to pro-
tect the cell from all danger of leakage. When aome pre-
servative liqnida are used, a scum is frequently found upon
tbe Burface when it is placed in the cell, and this must
be removed immediately before the cover is laid upon it.

I believe this method to be perfectly secure against
leakage when carefally performed ; and some of my friends
have told roe that their experience (that of some years) has
been equally a atia factory.

In using soma of the particular kinds of preservative
liquids, it tviU bo fonnd necessary to make a eligbt change
in the manipulation. This will be best explained by mention-
ing a feiv objects, and tbe treatment tbe; require.

For the preservation of the Mosses, Algna, &a., Deane'a
compound ia much used, and considered one of the best
media. The specimen to be mounted should be immersed
in tbe compound, which must be kept fluid by the vessel
containing it being placed in bot water. In this state the
whole should be aubmitted to the action of tbe air-pump, as
it is not an easy matter to get rid of the bubbles wbicb form
in and aronnd tbe objects. The cell and slide mnat be
warmed ; and heat will also be necessary to render the
gelatine, ifec, fluid enough to flow from the stock-bottle.
The cell may then be hlled with tbe compound, and the
Bpecimen immersed in it. A thin glass cover ranst then be
vfaimed, or gently breuthed upon, and gradually lowered
upon the coll, taking care, as with all liquids, that uo

154 PSEPARATIOS iXD MOTOTISO

bubble* are formed bj tha operation. The cover may be
fixed by the &id of gold-size, Japan, or any of the neiial
TamifiheB, care being taken, as before, that all tbe compoaad
IB removed from the parts to nbich the varaieb is intended.
t« adhere.

The glycerine jelly of Mr. Lawrance, before mentiondt
reqnireH atmoet a aimilar treatment. " The object* to U
mounted in this medium afaoald be iminersed for aoine tinu
in a mixture of eqaal parts of glycerine and dilate alcohol'
(six of water to one of alcohol). The bottle of glycerine jelly
maet be placed in a cop of hot water nntil liqnefied, when it
moBt be need like Canada balsam, except that it reqniM
lees heat. A ring of aspbaltam varnisb roand tbe thin glu4
cover completes tbe mounting."

The Infusoria {aee Chapter IV.) are aometimes preserved
in liquid; bat present many difficnlties to tbe stadent,
Different kinds require different treatment, and conseqaently
it is well, when practicable, to moant similar objects in twq
or more liqnida. Some are beat preserved in a I
aolation of chloride of calcium, others in Thwaites' liqaic
whilst a few keep their colour most perfectly when i:
glycerine alone. There can be little doubt that light is tli
bleaching agent in most cases. Many of them, howevon
are so very transparent that they present bat faint objeoti
for ordinary observation. For this reason, however, they ai '
sometimes dyed in solution of magenta or other colour, b
elsewhere noticed. The Desmidiacesi require somewhri
similar treatment, and may be mentioned here. The eolutiov
of chloride of calcium has been strongly recommended; bat
no preservative liquid seoms to be without some action npo*
tbem. Both of the above classes o( objects should bemoantel'
in shallow cells, so as to allow as high a microscopic powef
as poHsiblo to be used with tbem.

Entomostraca. — In every ditch or place where vegetable
matter exists, these little active, jerkiag pieces of life a
certain to be found. They are covered with a homy trana-
parcut shell, and are various in form. Mr. Tatem gives tba.

0? MICROSCOPIC 0BJECI3. 135

following, as the best way of preserviog them: — When
canght transfer to filtered water in watch-glasseH for twenty-
foar hours, in order that the contents of the laden inteatina
may be diacharged, Drair oS the water and add a little
Bpirit of wine, which qnickly destroys life. Bemove all dirt
hy aid of a camel-hair peQctl, nod place in a few dropa of
the medium used and water (half of each] until saturation
ia complete, and then put np in the medium in shallow onUs.
The mediom advised is Mr. Farrant'a, which will be found
amongst thoie recommended.

Many of the Zoofwjibs which are obtained on onr sea-
coasts are well preserved by mounting in cells, in the manner
before mentioned, with Goadby'a £uid, or distilled water
with one of the additions noticed amongst the preservative
h'qnida. For eianiination by polarized light, however, they
are uanally mounted in balsam (se* Chapter IV.), whilst
those in cells present a more natural appearance as to
position, Ac., for common stndy. The Polyzoa, also, are
exquisitely beautiful objects for the microscope, but require
Home little care. They should be kept iu sea-water until
their tentacala are expanded, and may then be readily killed
by plunging in cold fresh water. Thus all their beauty will
be preserved, and they may be then mounted in one of the
preseiTative liquids. Many operators speak well of distilled
■water well shaken with a few drops of creosote, as before
mentioned.

As to the nue of preaervatire liqnida with the Diatoraaeeffi
there are various opinions. Some experienced microscopists
Bay that there .is little or no satisfaction in mounting them
in this way. Dr. Carpenter, however, explains this differ-
ence by his instroctions as to what method should be used
when certain ends are desired. He says : " If they can he
obtained quite fresh, and it be desired that they should
exhibit as closely as possible the appearance presented by
the living plants, they should be put np ia distilled water
within cement cells ; but if they are not thus mounted within
a ihort time after they have been gathered, about a sixth

136 PREPAKATION AND MOUKTDfG

part of alcoliol should be added to the water. If it be
desired to exhibit the stipitate forms in their natural para-
sitism npon other aquatic plants, the entire mass may be
mounted in Deane's gelatine in a deeper cell; and soch a
preparation is a very beautiful object for black-ground
illumination. If, on the other hand, the .minute structure of
the Qilicions envelopes is the feature to be brought into
view, the fresh diatoms must be boiled in nitric or hydro-
chloric acid " (which process is fally described in Chapter
III.). It is very convenient to have many of these objects
mounted by two or more of the above methods ; and if they
are to be studied, this is indispensable. Mr. Hepworth
once showed me about one hundred slides which he had
mounted in various ways, for no other purpose than the
study of the fly's foot.

My friend, Mr. Rylands, successfully mounts the diatoms
in the state in which he finds them, and gave me the follow-
ing method as that which he always employs. He says that
he has had no failures, and hitherto has found his specimens
UDchanged. Take a shallow ring cell of asphalt or black
varnish (which must be at least three weeks old), and on the
cell, whilst revolving, add a ring of beuzole and gold-size
mixed in equal proportions. In a minute or two pure
distilled water is put in the cell until the surface is slightly
convex. The object having been already floated on to the
cover (the vessel used for this purpose being an ordinary
indian-iuk pallet), is now inverted and laid carefully upon
the water in the cell. By these means the object may be
laid down without being removed. The superfluous moisture
must not be ejected by pressure, but a wetted camel-hair
pencil, the size made in an ordinary qnill, being partially
dried by drawing through the lips, must be used repeatedly
to absorb it, which the pencil will draw by capillary
attraction as it is very slowly turned round. When the
cover comes in contact with the benzole and gold -size ring,
there is no longer any fear of the object being removed, and
a slight pressure with the end of the cedar stick of the

oe MicBoscoPic OBJECTS. 137

jteacil will render tba adheBion complete, and cement the
oover cloaely and firmly to the cell. When dry, an enter
ring of asphalt nrnkeS the mounting neat and comiilate.

The Fungi have been before mentioned ; bat it may ba
here stated that some few of the minnte forms are best pre-
served in a very shallow cell of liquid. For this purpose
creosote -water may be advantageously nscd.

The aTtteiiiiue of insects have been before noticed aa being
very beantifnl when moonted in balsam. This ia readily
accomplished when they are large ; but those of the most
minute insects are mnch more difficult to deal with, and are
leas liable to injury when put np in floid. Goadhy'e Fluid
Bsrvea this purpose very well ; but, of course, the object
most be thoroughly steeped in the liquid before it ia
mounted, for a longer or shorter time accordiug to the
thickness.

The egge of i-nsede afford some worthy objects for the
microscope, amongst which may be mentioned those of the
oommon cabbage bntterfliea (small and great), the meadow-
brown, the pusa-moth, the t^rtoiseahell bntterSy, the bug,
the cow-dung fly, &,a. These, however, shrivel up on be-
coming dry, and most, therefore, be preserved in some of
the flaids before mentioned. To accomplish this no parti-
cular directions are required j but the soaking in the liqni J
about to bo employed, &o., moat be attended to as with other

Glijferino may be advantageoualy used for the preserva-
tion of various innect?. These should firat be cleaned with
alcohol to get rid of all extraneous matter, and then, after
soaking in glycerine, be mounted with it like other objectH.
There is, however, a dif&cnlty in clearing glycerine from
the edge of the thin glass aover ; but Mr. Whalley told me
be met with no annoyance. After laying the cover upon the
olgect with the glycerine, he took away all the siiperlinoua
h'qnid with a small piece of lines, cleaning It at kat with a
damped piece of the same. The small quantity of water
which gets mingled with the glyceriae doe« no iujury. '

xi3 accyr:

-iii* «rU£mi sa '!« "anH smbdsE TeoBesy €9i:<C£^ fcr uy
«}>?nj*^': "^i u3ity» JLr Snfiiik. c lae *^^^ii£C3Ci Cmh, wud :
— '^ina im 'j»iL -wvt nL»e£ its- Taabmoi 2 vEsa. a coating
uf staLHi'jL liriaf-.ris£. f3i£ v^a. ia5i vbi irx ^ put it
T2iO!r tJjft 'Un Bif zsisnm^jT -w^iai 2«ix orSsr to icmore
£ZT r'jKriztt -yiarit iingxi rffnicrr jramS*, Ai^ cvcfbllj
£1*7 .:i<r t^ iili5» -Ri stbcsaxir-puBr, kie e&ve it another
Ka::;"!-r it zitt LrrSS-z^iie. im; viis. irj re^«ascd t&e wmsh-
fxf zyrjts^sm, saii ^ner iiaila g rrreK fs m tbinl coatiiig of
». vlf-r'xfr =1 tlks aasii^ stuczisr, x« evre is m final eoat of
gv.i'T^iz^ kZfi x** xriTtr \^ azj tncbSe viih ceDs doeed in
riLt ZL^r*^. Mr. HBsjc^, ai the lase place^aaid: — EUs
^v^fi -rsbir, Vjt etx« a ^TA. itsas fv tlie cover fint bj a thick
Hl;^ "-^f g?=i ^atr^ir — aljov tka to become stidrf ; next
Y^\ ha iLe g^ronise:, lar on the eorer, and then carefiillj
wafth o^ an tuperf hogs gljcerine. When perfectlj well-
wa^h^ axid dried laj on two or three ooats of gnm dammar
to finish it.

Some iDiiectf, sncfa as Maj-flies, ^., are, bowerer, often
j/rtnerred hy immersion in a solotion of one part of chloride
of caJciam in three or foor parts of water ; bat this has not
}jeen recommended amongst the preserratiTe liquids, as the
coloar, which is often an attractive qoalitj of this class of
objects, is thereby destroyed.

We have now noticed the treatment which mast be ap-
I^lied to those objects which are to be preserved in liquids
and cells. We may here state that all slides of this kind
should be examined at short intervals, as they will be found
now and then to require another coating of varnish round
tlio edge of the thin glass cover to prevent all danger of
leakage. The use of the air-pump, in the first instance
(iiH boforo recommended), and this precaution as to the
varnish, will render the slides less liable to leakage and'air-
b»bl)los, which so very frequently render them almost
worUiless.

or MICHOSCOPIC OBJECTS.

CHAPTER TI.

S BEUABES OK

Majjt objects are almnafc worthleaB to the roicroscopiat tintil
extraiDeons matter is removed from tliem; and this is fre-
qaently difficult in the estreme to perform satiafactorily. Aa
an inatanoe, certain IToraminifera may be raentinned in which
the cella are placed one upon another, c on iieq neatly the ob-
ject mnst be reduced to a certain degree of ihimtrss before a
ingle nniform layer of these cella can be obtained to ahoi^
aomethiog of the internal arrangements.

Mmt animal and vegetable forma require an examination
of the separate parta before much cafl be known abont them.
The maaa mnat be divided into separate portiooB, each part
intended to be preserved being cleaned from the naeleag
matter with which it is enrrounded. It will freqoently be
ad neoeaaary to make thin aeotiona, which from a very
tender substance ia no easy matter ; and much patience will
ba neeeaaary to attain anything like proficiency.

This making of aeotiona was not nntil very recently
nndertaken by many eieept tbose belonging to the medical
profession, bat I do not aee why this abould be so, aa mnch
may be accomplished by a pereevering and interested mind
where there is time for entering into the subject. I will
therefore make an attempt to give aorae instrnctions on this
snbject also. We will first conaider the cutting of sections
a hard substances, in which the ordinary knife, chisel,

140 FHEPiEATION IND KODNTIKO

&s., are of no avail. Most of these reqnire no particnlaT
care in mountiDg, bat are placed in balsam like the other
objects notiocd in Chapter IV.: where, however, anj Hpeeial
treatment is necesaary it will be commeoted Dpon aa

Shells, &c.— lb ia aeldom, if ever, necessary to poBneaa
apparatua for this process except a email thia saw n
with a steel blade, for which a piece of watch-apring ae
verj well ; a Gne stone such aa is ased for sharpening pen-
knivea ; and two smooth leather Btropa, one of which is ti
be used with puttj-powder to poliab the section after grind-
iufli, and the other drj, to give the final surface. It is, how-,
ever, very convenient to have three or foar files of different
degrees of Baeneas. A very useful implement in this proceat.,
is the Corondum file or robber, sold by moat dealers in
watchmakers' tools. It may be procured of almost any tdzQ
or grain, either circular or flat, and will cut almoat any-
thing. They poaaeae the very great advantage of not carry-
ing mnch, if any, impurity into the texture of the object
upon which they are used. The aholl, if very thick, may be
divided by using the watch-spring saw; and this sention
may then with ordinary care be rnbhed down with water on
the stone until one aide of it ia perfectly flat. When this ii
accomplished it must be rubbed with putty-powder upon
the strop, and finally upon the other atrop without Iha i
powder, This surface will then be finished, and mast be
firmly united to the slide in the position it is intended to
occupy. To do this a small quantity of Canada balsam may
he dropped upon the middle of the slide and heated over
the lamp until on cooling it becomea hard ; but this mast
be stopped before it is rendered brittle. Upon thia the
polished surface must be laid, and sufficient heat applied to
allow the ohjcDt to fall closely upon the slide, when slight
pressure may be used to force aside all bubbles, &c. Oa
cooling, the adherence will be complete enough to allow the
same grinding and polishing upon the upper surface which
the lower received. Whilst undergoing thia, the section

moat be uamioed foiM tine l» tine b ajeeftan ■tirter
the necMSMT degne of *J'"'— ^ bas leen mebcd. Vbca
tbia b tbe caje tb« Mctmi iboiiM be waJurt thoRM^Uj sad
dried. Il moat tboi Iw conred, wbkk ia beat dow by anng
ordinary Canada babBB, aa TNonncBdfd in Clia]:ter IT,;
or, if Uie sictkia ia to benoaiited dTj.it mut be fi«td 6oaa
bttlaom bj waaHtDg, or ■"—i"'^ if BMeaaarj, in tnrpeatiaa
or other solveuU.

Sections of some eiqnjaitelj beantifdl objects are cat with
tnoeb lees Irooble tban tbe abuTe. Tbe OrbiColite, for
inBt&ncp, mBj be prepared in this manner. Take the object
and hj presaure with the Eager rab the iiie apoa a flat and
BmDoth sharpening Etone *ith water until the portion is
reached which it Is wished to «bow. The etreo^h of the
object will easilj allow this to be accomplifbed with ordinarj
care. This side may then be attached to the glass elide
with heated LaLaam, as above described, and the object may
then be genttj nibbed down to the d^ree of thinness re-
qnired to show it to the beat advantage. After removing
all disengaged matter from tbe object by washing and
thoroQghly drying, it may be in>>Dnted in balsam in the
nanal maiiiit>r, when it is equally beautiful as a transparent
or opaque objec*. From this it will be seen that in man;
instances where a smooth stone is fonnd sufficient for the
wort (which is often the ease when the section is mounted
in balsam) the Goal process of polishjjig advised above may
be dispensed with, as in the Orbitolite, Nummnlite, &e., &a.
It is qoite necessary that the stones on which the objects
are rubbed be perffcllij fliif-, otheTwise one side must be
acted upon before the other, and it will he found impos-
sible to attain anything like nniFormity. Where it is not
practicable to cut a section, and the object is very thick, a
coarse stone may be first used to reduce it and the smoother
afterwards.

The consideration of the cutting of aeetiouB from ahelJs
would Bcareely be deemed complete without some mention of
what Dr. Carpenter terms the decalcifying process. Muriatio

acid is dilated with twenty times its volume of watar, tnJ
in this tho shell is imniersed. After a period, difieriog ac-
cording to the ihickoesB of the Ghell, the carbonate of lime
will be diaaolved away, and a pecaliar membrane left, shoo-
ing the Btrncture of the tbell very perfectly. This may ta
mounted dry, in balsam, or eonietimoa in liquid, accDrding
to the appearance of the object; bat no rule can begiien.
The discretion of the etadent, however, will enable him lo
choose the most suitable method.

Troro some shells it is easy to divide thin ptutee, oi
lamimu, which require nothing bat moanting in Canads
LaUam to show the texture very well. In working, however,
with those which are pearly, it will be found that eipe-
rienoe and patience are needed, as they are very brittle and
pecuharly hard ; bat a little practice will overcome these
diaicuhies.

Amongst the Echinodermata, which include the Btar-
fiehea, sea-hedgehogs, &o., there are many whose outer sur-
face is covered with spines, or thiu projections. Soma
of these are sharp and thorn-like, others blunt, longer or
shorter, and, indeed, of endless variety. In many of these,
when a section is made, rings are seen which have a coo:
centre, with radiating supports, resembling aectiona of :
of the woods. These are very beautiful objects, and methods
of procuring them may now be considered. It la the best
to cut as thin a section ns can safely be got with %he watch-
spring saw first, when the smooth sharpening stone may
be nsed to polish one side, which is easily accomplished with
water only. When this is effected, it must be washed clean,
and thoroiigJdy dried, and then may be united to the slide
in the same manner as before recommended for the Orbito-
lite, &.C. If it JB ever necessary to displace it on acoouni
of inequalities, bubbles, or other remediable fault, this may
be done by warming the slide; though too much heat mnst
be avoided, othemise fresh bubbles will certainly be pro-
duced. The covering with thin glass, balsam, &c., will
present no difficulty to the stadent; but he must remember

or KJcxofiOH^c omtrn. 143

[ Aai the transparencj u aomewliat increued hj ihia Lut

Corals are odea treated in this w»y, in order to rereal
their atractnre. £ic«pt, bowerer, th« etndeat hu h«d
mQcb practicf, he will often find Uub a most difficult tAtfc,
as man; of them are exceedinglj brittle and hard. He wil!
find the method before described eqaall; applicable lier«,
and abonld take both horizontal and TerticaJ sectionB.

Coal. — This enhstance is one of the most intereatiDg
objects to the microscopist. It is, of course, of veget&ble
origin i and thoagh it is is rnanj cases in each mioate
separate portions as to have lost all appearance of v^^ta-
tion, yet it is very freqnantlj met with in masses, bearing
the form, even to the minata maikiags, of wood, in Tarioas'
directions- la see this and prepire it for microEcopio re-
search, a aaitable piece of coaJ moat be obtaiuecl ; bnt in
every case the catting and preparation of these sections
reqaire great care and skill. Sometimes the coal is first
made smooth on one side, fastened to the glass, redoced to
the teqaieite degree of tluDnegs, and finished in tha method
before described. This mode of treating it is sometimes,
however, very tactalizicg, as. at the last moment, when the
Bection is ubont thin enoagh, it often breaks up, and so
renders the trouble beutowed upon it fruitless. The dark
colonr and opacity of coal render an extraordinary thinness
neoeHsary, and so increase the liability to this accident.

Mr. Slade recommends that the piece of coal, having been
smoothed on one side, be cemented on that aide to a gloss
slip by marine-glne of the best quality, quite free from
nndiasolved or foreign matter. Great care mast be taken
to press out all air-bn'jblea, the coal breaking up at such
places afl it gets thio, a hole resulting. It may then be
reduced in the nsual way, and when thin enough mounted
in Canada balsam and covered by thin glass.

Perhaps the beat method which can be pursued ia that
TBEommended in the Jliorographio Dictionary, which it
as follows ; — " The coal ia macerated for about a week in a

144 FHEPABATLON ASD UOUBTING

Bolntion of carbonate of potasli ; at the and of that time i(
ia possible to cnt tolerably thin alicea with a. razor. Then
bHcbs are then placed in a watch-glasa with strong nitlifl
acid, covered, and gently heated ; Ihey ioon turn brownish^
then yellow, when the procese mnat l.e arreeted by droppin,
the whole into a saucer of oold water, else the coal woul
be dissolved. The slicea thna treated appear of a darkU
amber colonr, very transparent, and exhibit the atructut^
when esiating, most clearly. We have obtained longitndinal
and transverse eectiona of coniferons wood from varion
oobIb in thia way. The apecimens are beat preaerved i
ghjcerine in cells ; we find that spirit renders them opaque^
and even Canada balsam has tbe same defect. Sohnltn
statea that he has brought oat the cellulose reaction witb
iodine in coBiI treated with nitric acid and c~ ~
potaah." Now and then in coal we meet wil
formed carbon -looking subatance whith is no mc
to work with than ordinary charcoal. From tliia it ia an
easy thing to procure iotereatin); slides.

CawitcWoal :s so close and firm in its strncture aa to be
much used instead of jet in the manufacture of ornamentaS
it takes a beautiful polish, and consequently presentfi ths
atndent with none bat ordinary difficulties in gettiii|^
eectioDB of it. Its formation is somewhat different from
that of coal, sometimea showing tbe transition very clearly

Fossil TTooi?.— This ia very often brittle and Teqnin
great care in cutting. There are, however, different kL
of fossil wood, but to obtain anything like certainty t
perform much work a lathe ia necessary. I know of
method bettiT than that given by Mr. Butterworlh, i
shall therefore make use of hia worda. First, I will brgj
with the cutting. To the framework of an ordinary fi
lathe I attach an upright epindle (see engraving),
upright apindle I drive by a band passing over
pulleys " from the wheel below. On the top of this w_
I fii my outting-diac, which ia made from a veij 1
piece of sheet iron, and ia about sii inches in

T I etarge with diamond -powder. To

T I hold my Hpecimon, and aa it oats I

amali brosli dipped in turpentine.

"With this method I have ont aectiona of foaail wood bo thin
that all ita atrocture haa been well defined and required
nothing hnt mounting in balsam; thia baa been gilicnted
foaail wood. In cntting calcareous fossil wood, I have to
cnt the aectiooa thicker and grind them down. My grinding
apparatus is composed of leaden laps, whieh I make to
revolve in a horizontal position on the same upright spindla

1%i •»T3r»tT»^naff jsa> aflLAgac

Ta 'w^cuGL Z iz TCT sar.r.ring wmw. I lae tvo lafa» one for
rtngi j— "Vii^rrry^ t^ic- ^ipfflT &r flBocckzaf. I vae 2^ot. 1.
eixisj sai£ & zzLJit wsSBT wiSk tfe £alu and floor of emery
«x& 'uExrrr ^ -v'issr hl liie mecmi^ !■ pvcfAiiiig a qteci-
moL, I fr« £75Eiif & sxcGcck irfMf on oae aide, and then
£z fs ^^ a poiSe ^ siiSaaSy of lock a sae as will suit mj
ipggrenrgg . ^rm Caai^3a bahM, I then redoee it in IhidnieBS
OL tkji TznA lap t2! I bcein to see tlie liglit tliroogh it.
T^«B. I he^s, wish the tmtxdiang lafs and redoee it with
Sfjrar c€ CBeej vorul evaj pait of its stmcliire is distinct.
If I fhfiom to pofidk the qwdmen I do so on a lap made
c^ plnth doth or eoSton Tcvet and potty-powder. I then
fi^Mt them off the dide on wlndi they bsTe been gronnd,
and £x them on another with Canadla balsam. I prefer,
wb<Te it is pia^cticaljle, to moant them in balsam nnder a
tbin eorer in the nsoal way, as I am satisfied that the
stmctnre is better brought oot.

In JlirU there are often found remains of sponges, shell?,
"D'tAUimzcesd, &c, ; bat to show these well, sections mnst be
cat aild polished by the lathe and wheel of the lapidary,
which the microscopic student seldom possesses. Thin chip-
pings may, howerer, be made, which when steeped in turpen-
tine and monnted in balsam, will frequently show these
remains very well.

Teeth are very interesting objects to all microscopists,
more especially to those who give much study to them ; as
the class of animal may very frequently be known from one
solitary remaining tooth. To examine them thoroughly, it
in necessary to cut sections of them ; but this is rather diffi-
cult to perform well, and needs some experience. Some
inNtruotions, however, will at least lessen* these difficulties,
itnd wo will now endeavour to give them.

B notions of teeth and bone may be successfully made by
rubbing ulicos out with a saw between two plates of ground
glnNH, with wntor and a little powdered pumice-stone, the
oM ntul partially worn glass being kept for the final
polishing of tho aeotions.

or Miciostoric cutca. 117

Tt ia genersHj Uwogbt that Canadk VW™ iBJnre* the

Ener raarbiogs of tbcae aMttoaa, eoiisttjneatlj. they aim
almost, invariablj nramited dry. A this piece ia Srat cnt
from the tooth with the aaw of wktch-vpriag bc£:Te
meottoned, if possible; bat ihciDU the solatajKe be too
hard for thiE, the wheel and Iath« most be nted with
diamond dast. If chia cannot be procnred, there ts bo
alternative bat to rnb down the whole Eahstance as thin as
practicable on some coarse stone or file, or best of all th»
corondam robber. The snrfai^ vill then be ivngh ; bat
this may be much redaced by mbbTOg apon a flat abarp-
eniDg atone with the finger, or a Email piece of gntta-percba
npon the object to keep it in contact. The scratches may
be mnch lessened by tbis, hut not so thoroughly removed as
microscopic eiaminalion requires in dry sections. It most,
therefore, be polished with the pntty-potrder and dry strop,
aa recommended in the working of shell -sections. The
other side of the section of the tooth may then be mbbed
down to the reqaisite thianesa, and polii^bed in the same
manner, when the dnst and other impartties mnst be re-
moved bj washing, afler which the section must be carefnlly
dried and mounted. Som.etimeB it may be deemed desirable
to make a preparation of the teeth in situ ; for this pnrpo?e
tate the lomer jaw of some animal like the rat, weasel, or
gninea-pigi and soak it in absolute alcohol first, let that evapo-
rate oat, then soak in the aolution of balaam and benzole ;
when that has evaporated to hard neas, grind down the jaw as
a section, the teeth are fiied in by the baleam. Some of
these sections are equally interesting aa opaque or trans-
parent objects.

The dentioe of the teeth may be decalcified by immeraion
of the section in dilute muriatic acid; after drying and mount-
ing in Canada balsam it presents a new and interenting
appearance, showing the enamel fibres very bcauliFully
when magnified about three hundred diameters. A friend
tells me that after snjjmoraion of the whole tooth in the acid
ho has been able to cut aeotiona with a razor.

Sbciioks of Bone. — With the aid of tlie microscope few
fragmeDtary renmiDB have proved bo DEeful to llie geologis
and Btudents of the foBsil kingdom a.8 these. Fro.
epeoimen many of our naturaliata can teli with certaintj U
irhat class of animal it baa once belonged. To
tbia point of knonledge much atudj ia necessary, and sectiona
of Tarioua kinda ahoul J be cut in Huch a manner as nill beat*
exhibit the peouliiiritiea of formation. The methods i
accomplishing this will now be conaidered. It may, h
ever, he first mentioned that the chippings of some boneC
will be foasd Dseful aow and then, aa before stated t
flint, thongh this is by no meana a satisfactory way of pro
ceeding. Sometimea the banes may be procured natnrally n
thin that they maybe examined without any cutting; and ontjF
require mounting dry, or in fiuid, as may he found the besfi

When commeucing operations we must provide the a
apparatus aa ia needed in. cutting sections of teeth, befoti
described. A fine saw, like those used for cntting braa^
&c., two or three fiat filea of difierent degrees of coaraem
two fiat " aharpeniag " stones i aud a leather strop t
pnttj-powder for polialiing. As tbin a section aa poasibli
should first be out from the part required by the aid of thi
fine saw ; and it is better when in this state to aoalc it foi
Bome short time in carophine, ether, or some other spirit t(
free it from all greaie. With the aid of a file we may no«
reduce it almost to the necoasary degree of thinnes
proceed aa before recommended with teeth. The " sharpeii<i
ing " stone will remove all acratchea aud marks suffioientl)
to allow it to be examined with the microacope to see
ground thin enough ; and if it ia to be mounted dry w
polish it with putty-powder and water upon the strop to H
high a degree aa possible, and having washed all remain
polishing powder, &c., from the aection we must ploc
npon the slide and finish it as described in Chapter
But where these sectiona are reqaircd for mounting i
balsam a less amount of ]ioJiKli is necessary ; thus rendering
the whole prooeas much more readily completed.

OF MICROSCOPIC OBJECTS. 119

Xf the bone is not safSciently hard in ita nutare to bear
the above method of handling whilst grinding and potishing
— SB some are far more brittle than others — oa thin a sectbu
aa possible mnst first be cut with the saw, and one surface
groond and polished. The piece mnst then be driud and
united to the glass bj heated halsam io the same matmrr
shelU, &c. After which the superabundaQce of balaum
mnst he removed from the glasB; then rub down upon the etona
and strop bh before, Gi'eat care must bo taken that the oaoala
be not filled dnring the process with the dnat of the bone,
r of the polishing material. Dr. Beale, in the jonrnal of
the Q. M. C. takes occasion to say " that he cannot admit
that the best way of preparing such sections is by grinding
' ia too liable to fill the canals wilh di^hi'ie." Hu
reeommendB that a fresh bone he taken — and a aniall slice
off by a strong sharp knife. Thi* is then to be ini-
mersed in. carmine diaaolred in ammonia — the ammonia
being first nentralized by acetic acid. The wal'.s of the
Teasels ivhich penetrate the lticiiu(B and canalictiU are by
this means stained crimson, and thus the trae sttuctnre of
bone is rendered viaible. When the polishing ie completed
whole slide must be immersed in cblorotorm, ether, or
e other spirit, to release and cleanse the section, wheu
it may be monnted as the one above mentioned.

lome bare recommended a. strong solution of iainglaaa to
e: the hiilf-ground teeth or bones to the gkas as causing
ra to adhere very firmly and requiring no heat, and also
being readily detached when finished.

The reason why the sectiona of bone are nanally mounted
dry is that the lacimis, bone cflls, and canalicuU (re-
sembling minute canals) show their forma, &c., very per-
fectly in this state, aa they are hollow and contain air,
whereas if they become filled with liqnid or balsam- — -which
does sometimes occnr — they become almost indiatingoiahable.
There are some dark specimen?, howevor, where the cells are
already filled wilh other matter, and it ia well to mount these
with balsam and so gain a greater degree of transpareDcy.

150

To obtain a true knowleUge of the *trnotnre of b
secUooB ina:(t be cut as in wooi], botb tranaver^ly and'
longitudiaallj ; bat vith fos/il bones, without the lapidary's
wheel, it is a laborioas ls.sk, and incleed can seldom be
properly accomplished. In this place, alao, it may be
mentioned that by submitting bone to the action of mnriatic^
acid dilated tea or fifteen times nith water, the lime, &c.,
diaflolved awaj and the cartilaj^e ie left, which may be cot
into sections : la camtic polasli the animal matter i
rid of. Both of these preparations may be mounted ii'
flnid.

The tncthod of cutting thin sectjous of bone may be t
employed with the stonea of fruit, vegetable ivory, and si
like Bubstancea ; many of nhiuh show a moat interesting
arrangement of cells, especially when the sections are trans-
verse. Most of these objects present a different appearand
when mounted di-ij to that whioh they bear when in dalsani,:
owing to the cells becoming filled ; and to arrive at a. tm^
bnonledge of them we mnat lia<re a specimen mounted iet
both ways.

Some will perhapg remark that moat of the directions for
section cntting are giren to those who are totally without
artificial power, and must rely upon
tioQs. I reply that these hiuta are
bat Mr. Butter worth's directions t
ample, that a repetition of them at the i
of " sectiooal " substance would be n

To those who study polarised light, few objects
beautiful than sections of the different kinds of horn.
will brieily inquire into the best method of cutting t
There are three kinds of horn, the first of which is bard,'
as the stag's, and must be cut in the same manner as boaft.
The second is somewhat softer, as the cow's. The third id
another and still softer formation, as the " horn " (as
termed) of the rhinoceros. In cutting secttoaa of the tira
e should succeed best by using the machine iDveDtedi
for these purposes, which I aliall shortly describe when t'

wu manual exelw

ostly given to
) the lathe are so
intion of each cl

e tautology.

or loCBOsconc osjects. Icll

I Bsthod of cutting wot-i u coQBiderei]. To aii nj in iiaa
D the horn is hard it mast be boiled far a. shorl time in
water, after wLicli the cutting will be more e&^ilj affect«d.
The BectiuDS sboaiil be b<jt!i truuTerw and longitadinaJ,
tliOBe of the former often ehowing cell* with beantifnl eroEses,
the coloars with the selenite plate being tmlj splendiil. Of
this class the Thiaoeeros horn ia one of the hast; bat the
bnSalo oIeo aSbrds a rerj handsoiiie object. The coir'tL, and
indeed almoKt esery diifcrent kind of horn, welldeserreB the
trouble of mounting. Whalebone, when cut tTansTer»elj-,
strongly resembleH those of the third and soFler formation.
A!) these are best Been when mounted in Canada babam,
. but care must be taken that thej have been thoroughlj dried
after catting, and then steeped in turpentine.

An ioteresting object maj cIm be procured from whale-
bone bj cnttiug long EectioDS of the baiiG of vhich it is
composed. Dona the centre of each hair we shall £ad a
line of cellB divided from one another very dintinctly. And
(a§ recommeaded ia the Micrograph ic Dictionary) if
whalebone be macerated twenty-four hoars in a solation of
canstic potaeh it will be so^ned, and by afterwards digest-
ing in water, the outer part will be resolved into nameroaa
transparent cells, which will show more plainly the stracture
of this curioaa sabstance.

An object nlijch frequently comes to the band of any
man who moves aboot in the world is a porcupine quill.
Thia ia a really valuable object for the micrOoCupist. Trans-
verse and longitudinal eections possess their respective
beaaty; and their appearaace varies somewhat as to the
distance from the poiat at which the section is made.
Soaking in hot water for a short time renders it easy enough
to cut, and when dry and mounted in baJaam the student is
well repaid.

In a former chapter, hairs were mentioned, their many
and interesting forma, and their beauty when nsed with
polarised light. The sections of tlieni, however, are no less
a matter of study, as this mode of treatment opens to sight

i"* " ■ ' ■ - - -

•eitna «i«qHBi,iMK ffan ■ ^tmm&j ot ham batwiit
tMiit|Matf M^vUcfc hf f «MM» hJa thf finnly

c*M^ lofalker to ■■•« tke wq wiwd poitioBa to bo cut
«tt ft file. O&cn take m immik of the bain and d^
it ado gvs or ^m^ ahich gRMit wbatdijftBoliditjcqa^
towooA. Beetwaaf tkk an Oca cat with tfae ma^iM
■Mlioirf a EUIe ftrtkcr <n, aad tkeae maj be loomnted In
balwM. TIm &■■«■ bair ia eanlj proened in tbe dedndl
aectiaaabT diavugaa doarlj a* poanble a second timeuj'
dcanang from tlia lalli^, te^ bj carefallj washing. Moit >
bain, howerer, abonld be eiamined botb transTeTsely and
loDgttiidinallj. It ie not diScalt to procnrc the latter, aa
we majr generallj tplit them with the aid of a sharp razor.
In a great namber of hairs there is a quantity of greaBf
matter which most be removed hj soaking in ether or some
other Bol*ent before moDDtini;.

We may neit consider the beat method of procnring
Hctions of wood, which most be cut of each a degree of
thinneas as to form transparent oT^jecti', and eo display all
the secreta of their structure. There is no monotony ia
this Btody, UB the forma are so various, and the arrange-
ment of the cells and woody fibre so diSerent, that the
microscopJBt may find endless amaaement or atady in it.
From a ainglo Bcstion the claes of trees to which it baa
belonged may bo known, often even when the wood iafoeiil.
Tho apparatus best adapted for entting these aectiona ia
made aa followa ; — A flat piece of hard wood, abont eiz
indies long, four wide, and one thict, is ohoBen, to which
another of the same siKe is firmly fixed, so as to form, in
u eidu view, the letter J. On one end of the npper aurfaca
is fWatened a brass plate, perfectly flat, in the centre of which
u circular opening ta out about half an inch in diameter.

■bofe tW Mi&M of tke hcHi pWc H^ MW koil ^ «

ly BOOB c£ tha InOoa aoMr Moti"

iiiiiilaiil liiililiii I'l ■ I wiMii Aa'totkcQ

of wbidb otj ecti AnaH ha ea^ ao foper dptliuMi cmb ba
giren, m tliia difioa ao pc^^ Aat H)tU^ list BqwrinMa
can be kof goide. na MiMa ttodmaa caa be oUuaed by
woiting tlie Kttw Badenoitk uaufara degna, tbe bead
bong marked fbr Uub pnrpaaai aad wkacllwsdfaalkBee to
be ent ia ver^ mBch smalla' thaa tbebola in the bnas plate,
it may be «edged witli corfc.

*Am this instrnmeiit U peeoUarij adapted for cattutg
wood (thoQgh D5ed for other eabstanMS, as before men-
tioned), I Hball notice a few particolan coDcerning tbis
branch of SM:tioii8. It may here be remarted, that to
obtain asything iike a true knowledge of the natore of
wood, it should be cot and examined in at least two direc-
tions, across and alon-j. The piece of nood ia often ptoceU
n spirita for a day or two, so that ail lesinoua matter may
be diaaolved oat of it ; it moat then be soaked in water for

M. Mouohet, ia ordor to avoid all danger of "bennia" in oiitting

d smitioin, procured a knife wilh a. seniicimulsr l..lodB, Thii WM

«..ui n. fh^ ^...1 nr.™ „ Hat |)late, in ordor to revolve, lU v- ■"'■"

1 ._ .j^g loTorogo fiirftiiyi

can it, tbe han<Ile being long en!

rer. The wood supporter bci^ ^'"■"■'•^ '" » '•'
knife is esail 7 brougbt round, and tlie seotiuu

it tiy a strculitr

lul rnEriHATioN and mounting

tbe same length of time, so aa to eoftea aod render it esLtf
to cat. Sections mtij tben be oLbaiaed in the manner juBt
described, but they often curl to auch a degree from thei«
previooa immersioti ia water aa to render pressure necesBBj^
to flatten them until dry, Tbej are often mouoted dry,
and require no care beyond other objects, as in. Chaptei
III. Home, however, ara best mounted in bah
ticolarly the long sections when used for the polariscope^
these must he soaked in turpentine, and the greatest c:
taben that all air-hiibbles are removed. Others are thoughb
to be most useful when moantcd in shallow cells with bi
the jire^eryad'ufl liquiiU mentioned in Chapter V.-
Bpirit and water, chloride of calcium solution of the etrengtll
of one part of the salt to three parts of distilled water, &e,.

The above " BedloTi-cutteT " may not be within the ti
of every student, nor is it absolutely necessary ; though where
any great nujiiher of specimens is required it is very use' '
and insnres greater uniformity in the thickness, Manj
employ a razor for the purpose, which must always be iepi
sharp by frequent stropping. Sections of leaves also maj
bo procured by the same means, though, as before mentianedi
they are BOmetimes divided by stripping the coatings o^
with the fJQgera. The cells which come to sight by cutting
some of the orchideous plants are most inteieBting. Tocal
these leaves they may be laid upon a fiat piece of cort, thni
eiposing the razor to no danger of injury by coming in
contact with the BOpport. It may be mentioned here that
the ra^or may also be used in cutting seotiouB of the r
than which a more beautiful object can scarcely be found
when viewed transversely, as lb shows the stellate arrange-
ments of the parenchyma. This should be mounted irjii
In the same way sections of the leaf-stalks of ferns may also
be cut, Bome of which, as Dr. Carpenter states, show the
curious ducts very beautifully, especially when, cnt rather
obliquely.

It has been found a ready method of catting sectione oj
the rueh and such like plants, to suck n, solution of gam nj^

or

155

• into the pitb, and when ttis is dry thia seoLioua oonid Le
ont and the gum waahed out again, and lliese could ba
mounted in balsam.

The plan adopted by moat practical histologiBta for cut-
ting aections of soft tiaaoea ia aa followa : — The tissue to ba
cat is lirat hardened bj immersion in a chromic acid boIu-
tion varying in strength from 0"25 to 2 per cent., or by im-
mersion in alcohol. The subatance to bo cat may then be
embedded in melted wax and Bpermaceti, ia proportions
suitable to the nature of the substance to be out; when
this is cold the section may be cut with a razor ground
flat on one side, and may then be floated off in spirits of

These sections mount very well in Canada balaani, if
after being removed from the spirit they are immersed in
oil of cloves till they become ulear, then put into turpentine
before the balsam. The thinneas of the section will depend
very much on the deiterity of the operator, but section-
cutting iostraments for soft tissues cau now be obtained at
most scientific instrnment shops.

When sections of softer aubstanoea are required, no instrn-
ment can be compared with " Valentin's knife," which con-
sists of two steel blades lying parallel with each other and
attached at the loner end. The distance of separation may
be regnlated at will by a small screw near the handle.
When, therefore, a section is wanted, the substance must
« cat through, and betwixt the blades a thin strip will be
foand, which may be made of uoy thickness, according to
the distance of their separation. By loosening the screw
the blades may be extended, and the section may be floated
OQb in water if the damp wilt not injure it. The knife cats
mnch better if dipped in water or glycerine immediately be-
use, and also when the substance to bo operated npon
is wet, or even nnder water altogether; but care muat be
taken, after use, to clean the bladoa thoroughly and oil them
ire laying by, if the place is at all damp. This instru-
ment is most Dseful in such aubjects as anatomical prcpara-

t!ona where the sections are required to ahow the position d
the dilferect veaeels. &c. ; bat, aa before stated, ia very tah-
able for all soft sabstuDcea. As an instance of tlik, it may
be mentioned, that it is frequently naed iu catting BBctions
of spoDgea ; but BB theae aie oftea very full of apicaki
it is much better to preee the »pooge flat nntil dry, and than
oat off thin efaavings with a very sharp knife; these stiavii
ioga will eipand when placed in water. After this thay
may be laid betirixt two Sat enrfacea and dried, when they
may be mounted as other dry objects, or, when dtisirable,u
balsam.

Valentin'a knife ia very mnch need in taking aections
skin, which are afterwarda treated with potash solution
Bcida, &a,, to bring ont in the beat way the different por
tioDS. Dr. Lister's mode, however, of getting- these ia tbu
given in the Microscopic Journal ; — " Bat I afterward
fonnd that mucK better acctiena conld be obtained froE
dried apecimena, A portion of shaved aealp being place
between two thin slipa of deal, a piece of string is tie
round tbem so as to eseroise a slight degree of oompreBsioa
the preparation is now laid aside for twenty-four honi
when it is foand to be dried to an aJmoet horny conditio
It then adheres firmly by its lower surface to one of tl
slips, and thua it can be held aecurely, while extremely thi
and equable sectiona are cut wilh great facility in any plai
that may be desired. The^e sections, when moistened wit
a drop of water aud treated with acetic acid, are as w<
suited for the investigation of the muscular tissae aa if thi
had not been dried."

There are many who almost confine their attention <
polarized light and ita beaulifnl efiecta. Such would ni
deem theae efibrta to aid the etndent in cutting si'ClioD
complete, without some notice of those which are take
from various crystals, in order to display that cm'
beautiful phenomenon, the rings \eilh a cross. The
roent of these is somewhat changed by tbe crystal w!
affords the section ; bat nitrate of potash gives two seta

OF wcsoscopic OBJECTS. 157

TingB with a cross, the long line of which posses tirongh
hoth, the short line dividing it in the middle.

The process of catting theae Beetiona is rather difficolt,
it a little care and perseverance will conqner all this. The
following is extracted from the Encijelop<Edia MetTopolitana :
" !Nitre crystallizes in long sii-sided prisms whose tectioa,
perpendicalar to their sides, is the regular hexagon. They
are generally very tonch iotermpted in their strnctnre; hnt
bj turning over a consideralile quantity of the ordinarj
saltpetre* of the shops specimena are readily found which
have perfectly transparent portions of some extent. Select-

ine of these, cot it with a tnlfe into a plate above a
quarter of an inch thick, directly serosa the ajis of the

a, and then grind it down on a broad wet Sle till tt
is reduced to abont one quarter or a sixth of an inch tbick,
smooth the anrface on a wet piece of emeried glass, and
polish on a piece of silk strained very tight over a strip of
plate-glass, and rnbbed with a mixture of tallow and colco-
thar of vitriol. This operation requires practice. It cannot
be effected unless the nitre be applied wet and rubbed till
quite dry, increasing the rapidity of the friction as tJie
moisture evaporat-es. It must be performed in gloves, as
the vapour from the fingers, as well as the slighteat breath,
dims the polished sarface efiectually. With these precau-
tiona a perfact vitreoas polish is easily obtained. We may
here remark, that hardly any t^vo salts can be polished by
the same process. Thus, Bocbelle salt mnst be finished wet
the silk, and instantly transferred to soft bibnloua linen
and rapidly rubbed dry. Esperjenoe alone can teach these
peculiarities, and it is necessary to resort to contrivances
(sometimes very strange ones) for the purpose of obtaining
good polished sections of soft crystals, especially of those
easily soluble in water.

Sometimaa tlie saltpetre of the shops is nitrate of mila, and as

is sligbtlr deliqnoaconc, it ia wal! to be cortaia that ire have the

nitrate of jjaliuA, wliiuli ia free from thi^ defect.

0w -li-ti'' «tir wfl,— M Intud 9v. 1 "'
nfl^ i^ v^ ooM-, l«t Oe irntiillj a
|iii¥iliiiji, tbewM alwMl too grcst br tks
■Mt be left to tb ^fiimrj. Tiam tmnamm
hovefcr. v«f W MM hj MBg k pbto of iea
formtdotmbamtami^iMaaABtm.

TTiT ■«1«ilin,lh<w iiHii

tiaa a fes' JtScahiw «Ud way b» met
ifBtdie^ Tbe tawmot rf tbcM k tbe
olJMt^ vkidi haye Mit rcMtaaea OMOgli in tliciBBdrai I
bnr cntttng eren witEt the sbnport inatminenis. Thia
often be remored bj antkiiig in » Botutioii of gnin, and
3rjiDg, wbieh wilt render the sabBtanee firm enoagh to be
cut, vhen the teetiaag mn^t be steeped in water, and the
gum tbna removed. Small seeds, £&, maj be placed
wfti wbeQ warmed, and will be held Srmlj enougli when it
JH again cold to allow of them being cot into seclionB."
And, laetlf, where a eabstitnte for a micrOHCopist's hand*
Tice ii rfqoired, a cork wbicb fits anj tabe large enoogll'
may be taken and split, the object being then placed between
the two parts, and the cork thnist into the tabe, a sufficient
degree of firmness will be obtained to reaist anj neceBaatJf
catting.

• Mr. T. K, Parker informs mo tl

t'Bot-tnpport" when aeotionaare required, as follows :— ^"The miiturtf
use (or embBcldiDg objeots coDSists oreolld piiraffine (aidinar; pant-
'.o rery well) melted down and mined with » litfla

parafflDo oil, withoi
The mixture when
nut In the centre, t
mcltad mixture pou

which the

hard to be easily onfc.-'
._. _ _ siiitsble pieces, a hole a Boooped
to be cut placed in it, and a. little of tiM
miiLuru iiuuruu luuiid it. The seotiuos are cut with aa Dnjt>
SOT, which, OH well lu the object, must be continuallv wetted
irit. This method is iiaoful for all objects which are either tM
ir tho bund or too aoft or brittle to be cut in the ordinary way.
ipedallj ueeful for biitologiaal specimeDB, leiiTes, embryo^

or lEicBOscopio OBJECTS. 159

The ether process of drying tiesuea has been described by
Mr, Suffolk, at a meeting of the QueVett Microscopical
Clab, and waa communicated by Mr. Crooter to hitn— it ia
as follows : — A wide-montbed well-stoppered bottle muat be
selected. At the bottom is placed a slice from the bowl of
a tobacco -pijje, forming a support for a Berlin crucible with
its oovor. A quantity of fused chloride of calcium in frag-
ments ia placed at the bottom of the bottle, which ia nearly
filled with pure ether, so that the orncibla may he covered.
The tissue to be dried is planed in the crucible, end is covered,
if necessary to keep it from floating, by a piece of glass.
The ether takes water from the tisane, and the chloride
again takes it from the ether; ao that the section ia thus
gradually dried, and with aa little shrinking aa possible,
however delicate it may be. This process ia moat fitted for
the preparation of sacculent roots, tabers, or utema, and in-
deed ia only fit for those tissues which are not injured by
immersion in ether, or dissolved by it, such as fat, &a,, or
colouring matter.

DissBcnoN. — As I atated at the commencement of thia
chapter, no written inatrnctions can enable any student to
become an adept in this branch without ranch esperience
and no little atody. I will, however, describe the necessary
apparatus, and alterwards mention the mode of treatment
which certain objects require.

A different microscope is manufactured for the purpose
of dissection, most first-rate makers having their own model.
The object-glaaaea of many of these are simple, and conse-
quently not expensive ; bnt one of the great requisites is a
etage large enough to hold the trough, in which the opera-
tion ia otten performed. "Where thia ia the case it would
scarcely be worth the expense of getting a dissecting micro-
scope if the student were pursuing no particular study,
but merely nsed the instrument when an object to be
operated upon turned up accidentally. The ordinary form
ia much improved for this purpose, by having two wooden
rests placed at the sides of the microscope, upon which the

IfiO rBBPAEiTlON AXU MOOTING

hands may be supported wben working npon the aUge,
Thej should be n'eightj- enough to be free from danger of.

moving. These snpports nil! alao he found to remedy
mach of the weariaesB nhich inentabljr arises from baTiog-

to BOBtala the hands as well aj work with them. The
erector, as I before observed, is necessary to a yoang stadent;
but with a little practice he may work very well withont it,

We will now notice some of the instruments which ars
moat useful in dissection. Tno or three different sii
ordinary scissors should be possessed, but the shapes must
be as modified in others for many pnrposes, as those used by
Burgeons; a pair with the cutting parts hent in a horii
zontal direction, and another pair slightly curved in I
perpendicular ; so that parts of the substance operated upon
may be reached, which it would he impossible to tooch with
straight scissors. One point of these is sometimes bli
and the other acute, being thus made very useful in cpei
tabular furmations. Another forni of these is made, whera
the blades of the scissors are hept open by a spring, the
handles being pressed together by the fingers. Where '
desirable, one or both of these handles may he lengthened to
any degree by the addition of bdibU pieces of wood.

The Enu'es which are most nseful are those of the
Bmallest kind which surgeons employ in very delicate opera-
tions. These are made about the length of an ordinary
pen-knife, and are fixed in rather long flattiah handles;
some are curved inwards, like the blade of a scythe, othen
backwards ; some taper to a point, whilst others again
broad and very much rounded. Complete boxes
now fitted up by the cutlers, of excellent quality and
prisingly chfeap.

Needles.^ — These are very nsefal and should be firmly
fixed in handles as recommeoded in Chapter II. It is con<
venient to have theia of various lengths and thicknesses. If
curved by beating and bending to any required shape they
may bo re-hardened by putting them whilst hot into cold
water. Dr, Carpenter also makes edged instruments by

OF MICHOSCOPIC OBJECTS, 101

rtibbiDg down DeedleB upon a hone. They are more pleasant
to work with vihea $liorl, a,a tlie spring thoy iiave wliilst
, long robs them of mnch of their firmneBS, Glaee pointa
nutde by draning oat gIa°B rods to & point will be found
QSefnl in manipalating with acids.

A glass syringe is also nsefol in many operationa, serving
liot only to cleanse the objects but to add to, or withdraw
liquids from, the disseding-trough. This trough will now be
deBcribed, as many aahstaucea are so changed hy becoming
dry that it is impossible to dissect them nnless they are
immersed in water daring the operation. If the object be
opaque and must be worked bj reflected light, a small sqnare
trough may he made to the required size, of gutta-percha,
which substance will not injure the edge of the kniTea, &c. ;
bnt where transparency is necessEirj, a piece of thin plate-
glass must be taken, and bj the aid of mariue-glue (as
explained la Chapter Y.) sides affixed of the required
depth. As pins, &o., cannot be iised with the gUas troughs
and the substance must be kept extended, a thin sheet of
eork loaded with lead in order to keep it under water may
te used ; bnt this, of course, renders the bottom opaque.
When working with many thin substances, a plate of glasa
three or four inches long and two wide will serve every
purpose, and be more pleasant to use than the trough. A
drop or two of water will be as much liquid as is needed,
Kod this will lie very well upon the flat sorface. An these
' are the principal apparatus and arrangements which are
requisite in dissection, the method of proceeding in. a fen
cases may now be noticed.

Vegetables. — The dissection of vegetable matter is much
less complicated than that of animal ; maceration in water
beiog a great assistant, and in many cases removing all
necessity for the nee of the knife, especially if hot water can.
be used without injary to the objects, as is the case with
many. This maceration may be assisted by needles, and
portions of the matter which are not required may be re-
moved by them. When, for inatance, the spiral vessel^.-

—Iter w^ fa iwBiui bvm ffa qiinl TeMda,^u(li

B nji«t Am* to a deaa ri^ of giua, npe«Uiig Um p
I avi at iMt waaUsf well, geed ipMuacBS naj fa pn
} >MtiirtfawifavldfaBwntcduBO«eoftke|>TeK
lifBidi m tfa Bwwr dMcritud in Cfapter T.
fa ww u, B^ fa dried <m ike ifidc^ imm«r»ed id tnrpentin
■■d tfaa BOOBtcd tB fafaai ; Int liquid ia prel«raUe, eu '
fact ynmg wt M that natwal sppesiaaw. Certain kinda
I •(ft.tsUei reqnre a different Ufatnent to separate tlic
'nlTMBciU. Aapu«giiaiBCOii^)oaedof Tei7 bard vegetaU
Iter, and aame have reeommendcd the stems to be fir
I failfd, wladi will soften Uiem to such a degree that tbi
I naj eaailj be Kpaiated. Dilate acids are also occaiioDBJl
t Bsed to effect this ; and in eorae iastancps to obtain f
rapkidtt caustic pota«h ma; be emplojed ; but after any
these agents have been osed, tlie objecta mast be tboronghl
cleansed with water, else the dissecting icatmaents (i
perhaps the cell) will be injured bj the action of the
mainicg portion of the softeaing agent.

For the dissection of animal tisiues it is necessary that
the instrnmentfl be in the best order as to sharpnea.
and as the rales to be observed mnst necessarily be sotac*
what alike in manj instances, the treatment required bj
some of the objects most freqaently moonted will now '
deacribed. We may here remark that cartilage can
best examined by taking sections which will show the al
rangement of the ceils very perfectly. This, however,
plainly seen in the monse's ear without any section being
necPHsary. Glycerine, the preservative liquids before raea«
tioned, and Canada ba,lBam are all oied to moant it

OF MICEOSCOPIC OBJECTS, IGS

bnt pertflpa the firet-named maj be preferred in many
caaea.

Before treating of separate objectn it will be well to notice
wlftt M. Brnnetti has eatd on preparing anatomical speci-
mem. The proceea oonsiats of four atageB— viz,, waahiog,
divestiiig of fat, treating witk tannin, and deaiccatloii. A
Btream of pure water is injected through the blood-veaselB
and secretory ducts of the part to he preserved ; the water
is afterwarda espelled by meane of alcohol. To remove the
fat, the vessels are in like manner injected with ether,
which penetrates the tissnes and dissolvcB all the fatty
matters. These operations occapy abont two Loara, and
the object thns prepared may then be kept for a long time
in ether, if desired. A solution of tannin is next injected
in a aimilar manner, and the ether washed ont by a stream
of pnre water. The preparation is then placed in a donble-
bottomed veaael containiog boiling water — a sort of lain,-
marie — in order to displace the floid previously naed by
dry heated air. Air compressed in a reservoir to about
two atmospheres is forced into the vessels and ducts
through heated tubes containing chloride of caloinm : all
moisture is thus expelled and the process ia completed.
The preparation thus treated is light, and retains
its volnme, iis normal consistence, and all ita histological
elements.

Muscle. — This ia what ia commonly called the fleah
of aoiaiala. If a piece be laid upon the slide under the
microscope, bundles of fibres will be perceived, which with
needles and a little patience may be separated into portions,
Bome of these being striated, or marked with alternate spaces
of dark and light. Some of the non-sfriated or smooth class
of mnscle, snch as is found in intestines, may be prepared
for the microscope by immersing for a day or two in nitric
Bcid diluted with three or four parts of water, and then
separating with needles and mounting as eoon as possible.
Sometimes bailing is resorted to to facilitate the separa-
tion, and occasions Uttle or no alteration in the material.

163

TRErilliTION ASD MOrSTISG

nniler water with a fine camel-hair brasli very gently. 80 W
to remove tlie precipitatea of tbe gold Bait. Sections of 1
cornea so prepared maj be made on the finger b; a shaig
razor, aod must be etamined and kept in gljcerioe.

Liver, Kidney, Si'Leen, Lung, Ac. — Some parts wl
are too sofl to be cnt into aections in their ordinary Bt
are ngnally hardened by being eteeped ta a aolntion
cbromia actd, aboat two grains to aa ounce of water. Thi
win take HOme weeks according to the eubRtance, and U
eolation abould be changed now and then. Dr. Baatian, la
moanting, uaea Canada balsam partially dried to dispel tl
tttrpeatine, and then dilated to necessary coDsistence i>"
benzole. The section being cat from the hardened ai^aaj
washed in spirits of wine for some minutes, then a drop e
liijuid carbolic acid is placed on the slide where the sp
men is to be mounted. Take the specimen and let ite e
toach a piece of blotting-paper, and place it apon
carbolic acid, which will render a thin section transparen
in about a miante. Bsmove the soperflaoaa acid *
blotting-paper, when two or three drops of chloroform n
be poured upon the section and remain one ininnte. Droi
off and place npon the object the solution of Canada balsai
in benzole, and apply the thin glass cover. Or place
object in ordinary spirits of wine for about a minute to i
it, then remove into absolate alcohol for five minates.
it upon the elide and drain, cover with one or two drops C
benzole for about a miuute, tilt to drain off, and proceed (U
above.

Both these luetboda are good, but the first does n
always answer for sections of liver, aa they generally a
acted upon by carbolic acid; but few other tissues a
affected. Tinted specimens seem equally safe wlien monntej

Sections op BjtiiN akd SriSAt Conn,— Dr. Baatiai
gives hia experience of these tissues as follows :—I. ii
tbe section for about ten minutes in absolute alcohol dilat
with eight per cent, of water, then place uiion the glai

OF UICEOSCOPIC OBJECTS. 167

slide, and before it becomes dry poor over it two or three
drops of pjroacetic acid for about half a miaate. Tilt this
off and replace bj chloroform. Watch the effects, as before,
under the mioroBcope, and then cover with the Canada
balsaoi solution and fioish. These specimens, howeTer, are
not always permanent in their appearance, according to the
res nits of some.

Mr. Alfred Sanders gives his expeiieneo aa differing some-
what from this. Ho says — The brain, or other structore,
'□g, as QSual, hardened in chromic acid, the section is put
for a short time in spirits of nine, and thence transferred to
the creosote, which taakes it transparent in a fen minates,
when it ia placed in Canada balsam. The balsam will mix
easily with the creosote, or the solntiou in benzole may bo
employed.

TiACHB« o? Insects, &o. —The nature of theae was de-
acribed in Chapter IV,, but the method of proonriog them
was not explained, as this clearly belongs to diesecUon.
The larger tubes are readily separated by placing the insect
a water, and £xiog as firmly as possible, when the body
nust be opened and the viscera removed. ThotracheiB may
hen be cleaned by the aid of a camel-hair pencil, and
floated npon a glass, where they must lirst be allowed to dry,
and tben be mounted in balsam. Mr. Qaekett gives the
following method of removing the tracheal from the larva of
n insect; — "Make a small opening in its body, and then
place it in strong acetic acid. This will soften or decompose
bU the viscera, and tbe tracheae may then be welt washed
with the syringe, and removed from the body wilh the
greatest facility, by cutting away the connections of thu
in tubes with tbe spiracles by means of 6ue-pointed
soissors. In order to get them upon the slide, it must be
pnt into the fluid, and the tracheal iloated npon it ; afcer
which they may be laid ont in their proper position, then
dried and mounted in bLiIsam." If we wish them to bear
ir natural appearance, tbey must be mounted in a cell
with Goadby'fl fluid i but the structure ia emiieliiiiee _well

akf^ipdar witk cUwofera. I left itmM
B or c^U dafi. nb tmtMDt i ~ '^
BtaMer AiB of iuccte and canaca Ae viM
I'tobMiVt tbrongk th« onttf uAcgamcat, mad it I
•t*t«, pethaf, that Uie pouo« gUtnSM arc ino«t aaan;f di
eofttfA and traced to tbcir point* of attaebment.
drew tha roandiUea from Hie bodj, and, having plai
tii«m iritli a little wat«r cm a elide and covered them tritli a]
pieM of thin glaes, I fooud that, upon the applicatioa o
preeiore, the two glands ehot oat and protrnded from thai
Inwf of the mandlblei. I tore open one of the mandiblKfl
with needl(>«, bo as to distDrb the gland as little as poBBible..t
Thn ginnd then appeared as a closed aac, attached bj S 9
hollow norc], almiit the length of the gland itself, to the bi
of tha fang, where also was a large bnndle of maBColai'
flbro.

Frdii,— The moat interesting part offish to then
■oopio anatomiat is andoubtedlj the hreathing apparatn

or KicBoscoPic owtCTS. 169

■ It IB not a very diEcnIt matter to oppn the head and remote
the gills, which are Tery beantifiil. Uo^er the oaler covers
lie a quantity of thin plates or leaves (as of a book) nbioh
in different fishes are of varioas shapes, bnt are made like
net-work hy the Dnmerons veios and arteries which convej
the blood to be acted npon by the air and gases in the
water, as is dooe in the lungs of a man. These platee are
of such numbera that in a good-si^cd salnion the Enrface
eiposed has been estimated at two thonsatid Kqnare inches,
i.e., abont fonrteen aqnare feet. The beanty of these is,
of oonrae, not •perfedhj shown nntil they are injected, which

' will be noticed elcewhere.

Tongues, or Pawtes, of MoiLusns. — Of the nature of
these, Dr. Carpenter gives the folloning description ; — "The
organ which is commonly known nnder this designation is
one of a very singular natnre ; and we should be altogether
wrong in conceiving of it as having any likeness to that on
which onr ordinary ideas of such an organ are founded.
For, instead of being a projecting body, lying in the cavity
of the month, it is a tube that passen backwards and down-
wards beneath the mouth, its higher end being closed,
whilst in front it opens obliquely npon the floor of the
mouth, being, as it were, slit np and spread out so as to
form a nearly flat snrface. On the interior of the tube, as
well aa on the flat expansion of it, we Snd numerous trans-
verse rows of minute teeth, which are set upon dattoned
plates ; each principal tooth sometimes having a basal plate
of its own, whilst in other instances one plate carrica
several teelh." These palates, or tonguca, differ much
amongst the Gasteropods in form and size, some of them
being comparatively of an immense length. Many are
amongst the most beautifal objects when ejcamine^l with
polarized light, Tbey must, however, be piocnreil by dii-
•eetioD, which is osuajlj performed as follow! : — The animal
ii placed on the cork in the dissecting-troagb before men-
tioned, and the head and forepart cnt open, spread ont^ aod
firrolj pinned down. With the aid of fine iciuora or knif«,

170

the tongue miut be then detached from its fasUniogs, ani
ptac«d in water for a day or two, when all foreign matter ntf
with a little care be removed. lo what way it ahonid b*
moDnted will depend on the purpose for which it is iutendtd.
If for examinatioD aa an ordinarj otgect, it ma; be !>»
upon the slide and allowed to drj, which arrangement "Qi
bbow the teeth very well. If we wish to see it as it is nato-
rally, it wiiBt be monnted in a cell with Goadby's flaiij ; lint
if it is wanted as a polarizing object, it must be floated npuii
a slide, allowed to dr; thoroughly, and then Canada '
added in the usual manner.

Id the stomach, also, of some of these molluBCs teeth ut
found, which are very interesting objects to examine, aau
must be dissected out in the same ma.nner as ti
lontfnes.

Since writing the above, Dr, Alooct (whose very bea
tiful specimens prove him to be a great authority in tt
branoh) has published some of bis eiperience in the eecoi
volume of the third series of " Memoirs of the Literary a
Philosophical Society of Manchester." By his permission C
make the following extract : —

■■ This closes my present commnnication on the tongaw
of molluaca ; but as some members may possibly fed
inclined to enter apon the inqoiry themselves, I think il
will not be amiss to add a few remarks on t
which they are to he obtained.

" First, as to the kinds best worth the tronble of pHK
paration. Whelks, Limpets, and Trochnses sbonld be ti '
tirst. Land and fresh-water Enaih can scarcely be ret
mended, except as a special study, — their tongues beii^
rather more difficult to find, and the teeth so small tha
they require a high power to show them properly,
wonld appear, from SpallaDEani's description of the aaatoinj:
of the head of the snail, that even he did not make out thil
part, although, in bis curious observations on the reprodafl
tion of lost parts, be must have carefully dissected c
I snails than any other man.

OF uiCRosconc OBJECTS. 171

Aa to preserving the animals till waoted, the? should
aimply be dropped alive into gljcerine or alcohol. Gljcarine
ia perhaps beat where only the tongues are wanted ; but it
leaves the animals very sott ; and as it does not hardea
their mucns at all, thej are very slippery and diiEonlt to
work npon when so preserved.

" Then as to the apparatus required for dissection. In the
first place, all the work is to he done nnder water, and a
com mo a saucer ia generally the most convenient vessel
to use. No kind of fastening down or pinning oat of the
animal is needed ; and, in fact, it is much better to have
it quite free, that you may tarn it about any way jou wiah.
The necessary iuatrnments are a needle-point, a pair of
fine-pointed scissors, and small forceps ; the forceps should
have their points alightly turned in towards each otter.

"A word or two on the lingual apparatus generally, and
on its special obaractera in a few difierent animals, will con-
olade what I have to say.

"The mode of using the tongue can be easily seen in any
of the common water-snaila, when they are crawling on the
glass sides of an aquarium ; it may then be observed that
from between the fleshy lips a thick mass is protruded, with.
a motion forwards and upwards, and afterwards withdrawn,
these movements being almost coutionally repeated. The
action has thu appearance of licking; but when the light
falls suitably on the protruded structure, it is seen to be
armed with a number of bright points, which are the lingual
teeth, BO arranged as to give the organ the character and
action of a rasp.

"If JOQ proceed to disaectiOD, and open the head of one
of these moUusca (say, for instance, a common limpet), yoa
will find the cavity of the mouth almost filled with the thick
fleshy mass, the front of which ia protruded in the act of
feeding ; and on its upper surface, extending along the
middle line from back to front, is seen the strong membranoaa
band upon which the teeth are set. The mass itself consiata
of a cartilaginous frame, Bnrrouaded by strong muacles ; and

172 phefabatiox akd moestisq

these stractareB constitate the whole of the active part ol
the lingDal appara,tD8.

"Hat the pecoliaritj of the toothed membrane, nhioli
males its oame of Hlhon so appropriate, is, that there is
alnajB a cortsiiJerable length of it behind the moath, per-
fectly formei3, and ready to come forward and aopplj the
place of that at the froQt, which is conliouallj wearing anaj

'J"'- ....

" In the limpet this reserve ribbon is of great lengtfai
being nearly twice as long aa the body, and the whole of it
is exposed to view on simply reoioviiig the foot of the animal;
nothing, then, can be easier than to eilract the tongue of
the common limpet. But, unfortunately, what yon find ii
one kind of mollusc is not at all what yoa find in another.
In the Acmieas, for instance, which are very closely related
ia the limpets, and bavo shells which cannot be diatingatehe^
the reserve portion of the ribbon has to be dug out from tl "
anbatance of the liver, in which it is imbedded, that orgi
being, as it were, stitched completely Ihrongh by & lo:

loop of it It might he thonght a comfortabli

reQection that, at all events, one end of the ribbon t
always be fonnd in the mouth; but iq many cases this
abont the worst place to look for it. Perhaps it may appaa
etrange that in some of the smaller species, with a, retractil
trunk, a beginner may very likely fail altogether in I
attempt to find the mouth ; if, however, the skiu of the ba
be removed, oominenoing juab behind the tentacles, there «
be very little dlfiicalty in making out the trunk, whioheiths
contains the whole of the ribbon, aa in the whelk, i
front part of it, as in Pinjiura and Mitrex, where .
coil is also seen to hang from its hinder eitremity. . .
In the periwinkles the same plan of proceeding, by at on;
opening the back of the animal, is best : and on doing W
the long ribbon, coiled up like a watch-spring, cannot failt
be found.

" la the Trochusea, and indeed in alt the ScnlibraTuAiatl
one point of the scisaora should be introduced into t

OP MICROSCOPIC C

173

montli of the tiiiiniBl, and an inciaioiL made directly back-
wards in the middle line above to some distance bebiud the
tentacles; the tongoe ia then immediatelj brought into view,
Ijing along the floor of the mouth."

Dr, Alcock's method of disaection will he found to differ
in some degree from the general rules before given ; and
when the tongue ia dissected out be washes it for one hour
(ahabing it no^ and then) in a weak solution of potash.
After cleaning tboronghly in water, it must be mounted by
one of t1ie methods before mentioned.

Mr. Edwards, of New York, no moan authority, gives hia
experience as follows : — I nse a rather strong solutioQ of
canatio potaasa, the strength of which I cannot specify aa it
mnst differ with the species under manipulation, as some
ribbons (or tongues) are injured much sooner than others.
Plunge the whole animal ia this solation; in the case of
very small creatures shell and all. I have found it better
to let the animal etand nntil it dies and begins to decom-
pose, when it can readily be removed and falls in pieces.
The lingual ribbon is not so easily decomposed. Now place
and leave the animal in the pota.Bsa solution for some days,
or boil at once. Almost everything is now dissolved bat
the shell, some fet? fragments, and the desired ribbon.
"Wash carefully with fresh water, and if it is to be preserved
before mounting, remove to alcohol. To mount it, remove
from the spirit and boil a short time in, turpentine, when it
can be pnt up in Canada balsam. Mr. May espresses him-
self as " standing utterly agliast " at any man so interfering
with nature as to put up theae objects in balsam, thus
pressing and destroying their true forms. He recommends
a cell and a weak form of Goadby's solution.

Amongst insects, especially the grasshopper tribe, are
found many which possess a gizzard, armed with strong
teeth, somewhat similar to those of the mollosca. It
requires great nicety of manipulation to obtain theae for the
mioroBCope; but Mr. L. G. Mills, before quoted, gives the
following instructions :— Kill the insect with chloroform and

17i PUIPAKATIOK AKB 1C0I71?TD:G

place it in a yeeeel of water. Hold it down firmly witli a
pair of tweezers, and with the back of a dissecting knife
draw the head steadily from the body. The heard brings
with it the stomach, gizzard, and chief portion of the digestive
tnbes. Place all these nnder a dissecting microscope, when
the gizzard, being jnst below the stomach and darker in
colour, is easily distinguished, and may be separated by two
cuts with the knife. It then forms a short tube, the teeth
being inside. The opening-out of this tube, especially if it
be small, requires delicate handling : if the point of a fine
knife can be fairly inserted, then one firm cut downward
upon the glass will lay open the gizzard. Here great care
is needed ; and sometimes it is well to put a fine needle up
the tube, and cut down upon the needle. Among the
small weevils the membrane is delicate, so that great care
is necessary.

We have now considered most of those objects which
require any peculiar treatment in section-cutting, &c. ; but
in no branch of microscopic manipulation is experience more
necessary than in this.

OF MlCKOaCOPIC OBJECTS.

CHAPTER VII.

1. Injection is the filling of the arteries, veins, or other
vessels of animala wilK some coloured substance, in order
that their nalnral arrangernent may be made visible. This
ja, of conrae, a delicate operation, and needs special appa-
ratna, which I will now attempt to describe.

"2. Sip-ingB. — This is nsnally made to contain abont two
onncBB. On each side of the part Beit to the handle is a
ring, so that a finger may be thrust throogh it, and the
tharab may work the piston as in an ordinary syringe.
The plug of the piston most be packed with soft leather
welt oiled or greased, in order to free it from all danger of
any liqnid penetrating it, and fit so closely as to be perfectly
air-tight ; and if, when it has been used awhile, it is fonnd
that some of the liquid escapes past the ping into the back
part of the body, it mnst be repacked, which operation will
be beet understood by eraminiog the part. These syringes
are made of variona sizes, hot in ordinary operations the
above will be all that is needed. The nozzle ia about an
inch long, and polished so accurately that there is no escape
when the j>ij)*s are tightly placed upon it dry.

3. The pi2>es are nanally abont an inch long, to their
ends are afiiied thicker tnbes bo as to fit the nozzle, as
before mentioned, whilst a short arm prnjecta from each
side of these, so that the silk or thread which ia nsed to tie
the artery npon the thin pipe, may be carried ronnd these
arms, and all danger of slipping off prevented. The }>!pfs
are made of different sizes, from that which will admit only
of a very fine needle (and this will need now and then to be
cleaned, or to be freed from any chance obstruction), to

173

raEFiBAHOs isn mottsiixs

that which will take « large pin. These aizeB rnuBt alwajs
be at h&nd, as the vessela of BOme subjects are eiceedmgty
iniDnt«.

4. SlopcocJi. — This is a short pipe like a Bmall slrai^lii
tap, which fits Bccoratelj upon the end of the syringe like
the pipes, and also takes the pipes in the same oianne
The nso of thia is BbBpIntely neceseary when the object
BO large that one ayringe full of liqaid will not fill it.

DO pteTeotiie were ased, some part of the liquid woald
return whilst the syringe was being repSeuished, bnt tha
stopcock ifl then turned as in an ordinary tap, and all
danger of thia eSectnally removed-

5. Cui-ved needles. — These are easily made by heating
common needles at the end where the eye is situated, and
bending them with a small pair of pliers into a eegment of
a circle half an inch in diameter. They are, perhaps, mora
convenient when the bent part is thrown elightly hack
where it commences. The pointed end is then tbrnst into
a common penholder, and the needle needs no re-tempering,
as the work for which it is wanted is simply to convey tha
thread or silk inuler any artery or vessel where it wotdd bo
impossible to reach with unaasiated fingers.

6. A kind of forceps, commonly known by the name ot
"balldog forceps," will he constactly required daring tlii
process of injecting. These are short, nsoally very
but not heavy, and close very tightly by their own Hpring^
which may be easily overcome and the artery so released bj^
the presBOTo of the fingers. When any vessel has not been
tied by the operator, and he fiods the injected Quid escaping,
one of these " balldoga " may be taken up ai " "'
close upon the opening. This will cause i
terruption, and the stoppage will be almost
if it were tied,

7. When the ordinary mode of injection i
is necessary that the preparations he kept wa
time they are uecd, otherwise the gelatine or t
contain becomes stifle, and will not allow of being worked by

id allowed ta
little .

employed, it

m daring tho

which they

OF uicRosconc ojjJECTs. 177

■ the Byringe. For this pnrpose we mast procure Bmall
earthenware or tin pots of the size required, which will
differ accordiog to the kind of work to be done ; and to each
of these B. loose lid shonld be adapted to protect it from
dnat, &c. These pots must he allowed to stand in a tin
hath of water, nnder which a lamp or gas flame may be
placed to keep the temperature eufiicientlj high to insure thd
perfect fluidity of the mixture. The tin bath is, ])erbaps,
most convenient when made like a smalt shallow cistern ;
but some oIobo it on the top to place the pota npon it, and
alter the shape to their own cDnvenience.

8. We will now inqnire into some of the materials which
are needed in this operation ; the first of which is sisr.
This sabstance is often used in the formof jfue, hut it mnst
be of the very heat and most transparent hind. To make
the liquid which is to receive the colours for the nsnal moda
of injecting, take of this glue seven ounces, and pour npon
it one qnart of clean water; allow this to stand a fevr
honra, and then boil gently nntil it ia thoroaghly dissolved,
stirring with a wooden or glass rod during the process.
Take all impurities from the surface, and strain through
flannel or other fine median). The weather affects thi-i
a little as to its stiflhess when cold, hat thia must b<i
coonteracted by adding a little more glue if found too

9. Inataad of glue, gelatine ia generally used, especially
when the work to he accomplished is of the finer kind. Tbd
proportions are very different in this case, one ounce cf
gelatine to about fourteen ounces of water being suflicient.
This, like glue, must be soaked a few hours in a small part
of the cold water, the remainder being boiled and adder<,

' when it mnst be stirred until dissolved. A good siis muy
be made by boiling clean strips of parchment for awhili-,
and then straiging the liquid whilst hot through flannel j
bnt when the injections are to be ti-anaparent, it is of the
greatest importance that the size be aa colonrlesa as pos-
aible. For thiii t^urpose good gelatine must be employed.

I'i

PREPARAIION ASD MOUNTI

H,B Kelson's or Coi's: some persons of eiperience preTer th»
latter.

10. Colours.— The ske-Bolution above mentioned will
need some colonring matter to render it viBtble when in-
.iected into the vesBela of an animal, and different coloniB
are used when two or more kinds of Teasels are bo treated,
in order that each set may he easily distingnished by
sight. The proportion in which these coloors are added to
the aize-aolution may be given as follows : —

11. For

Bed 8 parts of size-solution

(by weight) to 1 part of vermilion.
Yellow... 6 „ „ 1 „ chrome yellow.

White ... 5 „ „ 1 „ flake-white.

Bine 3 „ „ 1 „ blue-smalt, fine.

Black ...12 „ „ 1 „ lampblack.

WhicLevor of these colours is used must be levigated ii
mortar with the addition of a very email quantity of wateo:
until evpry lump of colour or foreign matter is reduced to'
the £nost state possible, otherwise in the process of injecting
it will moat likely be found that some of the small chaitDelw
have been closed and the progress of the liquid stop[»ed.
^yhen this fineness of particles is attained, warmth sufficieab
to render the size quite fluid must be used, and the ooloar
added gradually, stirring all the time with a rod, It may
be here mentioned that where one colour only is reqoirad,
vermilion is, perhaps, the best ; and blue is seldom used
for opaque objects, as it reflects very little more light than

12. When it is wished to fill the capillaries (the minnte']
vessels connecting the arteries with the veins), the Micr<
graphic Dictionary recommends the colouring matter to
made by double decomposition. As a professed handbookJ
would be, perhaps, deemed incomplete without somi
tions as to the mode of getting these colours, I will h<

OF MICBOSCOPIC OBJECTS. 179

given in that wort. For red, however, vermilion,
Btated, may be used; but it nmst be carefully
examined by reflected light to aee whether it be free from
all colonrleaa crystals or not. It mnat first be nocked in a
mortar, and then the whole thrown into a quantity of water
and stirred about ; after leading it not longer than a qnarter
minute, the larger portions will settle to the bottom,
and the liquid being ponred off will contain the finer powder.
This may then he dried slowly, or added to the eize whilst
it in the manner before advised.
13. 7elIovi injection. — To prepare this, take —

Acetate (sugar) of lead SSO grains.

Bichromate of potash 132 „

Size 8 ounces.

Dissolve the lead salt in the narm size, then add the bichro-
mate of potash finely powdered.

free, and ia wasted ii

Some of the chromic acid
this aolntion, so the following is given ; —

Acetate of lead 190 grains.

Chromate of potash (neutral) ... 100 „
Size 4 ounces.

The first of these has the deepest colour, and is the most
generally used.

14. White injedion. — This is a carbonate of lead ; —

Acetate of lead IPO grains.

Carbonate of potash kH „

Size 4 ounces.

DisaolTe the acetate of lead in the warm size, and filter
through fiannel; disaolva the carbonate of potash in the
emallest quantity of water, and add to the aize: 143
grains of carbonate of soda may be snbstitnted for the car-
bonate of potash.

15. For bine injection, whick ia not, toweyer, muoli QM
with reflected light, tu before atoted, take —

ProBHiaii blae 73 ^oins.

OiaJicacid 73 „

Size 4 oQiioea.

The oxalic acid is first fioely powdered in. a mortar, i
Pmssian blae and a little nater added, and the whole th
thorooghly miied with the eize.

16. It raaj here bo repeated, that it is only when tb
capillaries are to be filled that there is any need to be at U
trouble to prepare the colours bj this doable decompoaitiol
and, indeed, coloars ground so finely maj be procured ibl
the above ioBtrnctions would have been omitted, had it n
been supposed that some students might find a donble pleil
sure in performing as mnob of the work as passible bj the!)
own unaided labonrs.

17. The process of injection may now bo considered;
it is impossible for written instructions to supply the plai
of eiperience. I will do my bust, however, to set the n
at least in the right way. There are two kinds of injeotio
— one where the object and colonrs are opaqae, and oo
quently fit for examination, by reflected light only;
other, where the vessels are filled with transparent colone
and mnst be viewed by traKsmiiled light. The first of the)
is most frequently employed, so we will begin with it.
the object which is to be injected, a vessel of the kind whi
we wish to be filled mnst be found ; an opening must ths
be made in it to allow one of the small pipes before n
tioned to be thrust some distance within it. When this il
accomplished, thread the curved needle with a piece of nil
thread, or very fine string, which some operators ruT
wilh beeswai. This thread must not be too thin, else
is danger of catting the vessel. The cord is then c
under the inserted pipe, and the vessel bound tightly Dpon
it, the ends being brooght np round the transverse armn^

OF uicBOsconc OBJECTS, 181

Bad there tied ; so that all danger of accidentallj with-
drawing the pipe is obviated. Care mnst now be used in
cloaing all the veaaelB which commmiicate with that where
the pipe is placed lest the injecting fluid escape j and thia
mnst be done by tjing them with silk. Should, however,
any of theBa be left open by ^cident, the bulldog forceps
tniiBt be naed, as before recommended.

18. The part to be iojected must now be immersed ia
Wftrm water, not, however, above 100° Fahrenheit, and left
until the whole ia thoronghly warmed. Whilat this is being
done, the coloured size most be made ready by the pot being
placed in the tin bath of warm water, which mast be of
jnEBcient temperature (about 110° Fahrenheit) to keep it
perfectly liquid. For the aame purpose, the syringe ia often
tigbtly covered with two or three folds of flannel; and,
indeed, there is no part of the process which requires mora
attention. If the anbatance to be injected is too hot, it is
injured; whilat, if any of the articles are too cold, the gela-
tine, or size, loses a part of its Haidity, and consequently
cannot enter the minute vesaels. When all is prepared, the
syringe, with the stopcock attached, should be warmed, and
then filled aad emptied with the injecting fluid two or three
times, care being taken that the end of the syringe be kept
beneath any bobblea which form upon the surface. The
syringe may then be tilled, and closely attached to the pipe
which ia tied in the vessel. Wif h a firm and steady pressure
the piaton must be forced downwards, when the substance
will be perceived to swell, and the colour show itself in places
where the covering is thin. When the ayringe is abiiosl
emptied of ita contents, the atopcook muat be turned to pre-
vent any escape of the injection from the subject. It must
then be refilled, as in the £rst instance, and the process
repeated. I say almost emptied, because it is well not to
force the piston of the syringe quite to the bottom, lest the
small quantity of air which frequently remains be driven
into some of the vessels, and the object be injured or quits
ruined. As the injection is continned, it will be found that

18-2

FKzrxKAxica AXD xovs-nsa

the force repaired grown greater, jet emre iniut be talcen cot
to n»e too mach, or the tbsmIi will bant, and render all thft
l&bonr fmitleae. The morement of the piston moat be
occa/BoaaiOf so slow aa to be almost itoperceptible, and foi
this reason tlie piaton-rod is Bometimee marked with L'
about one-^gbtb of an inch apart.

19. Of coarse, daring the whole procesa the injeetiu^
fluid and sabject moat be kept at a temperatare high enougli
to allow the liqnid to flow freely ; and the escape of a little
of it need canae no fears to the operator, as it ia almost im-
pMsible to fill a subject wiUioQt some loss. When the
injected object has received sufficient flaid, it shoald hare a
plump appearance, owing to all the TeBBela being well GlletL
The vesBel must then be tied np where the pipe was inserted
and tbe whole left in cold water two or tbree houie, &
which time it majr be monnteU ; bnt it maj be well to no
a few things which the beginner onght to know before enter-
ing into that part of the process ; and be maj be here informed
that it is not necessary to mottat the objects immediately,
otherwise it would be impossible for one person to make.
use of half of any large anbject, as it would be in a state
of decay long before each part conld have been examined;
and separated. Large pieces shonld be therefore immersed
in eqoal parts of spirits of wine and water, or glycerin*
which some think better still, and thus preserved in bottlei
until time can be given to a closer examination.

20. In operating npon large Bnbjecta, entire animals, i
the constant pressure required by the piston of the syringel
grows wearisome, besides occapying both hands, which if
sometimes inconvenient when working without assistaocft
To obviate this, another way of driving the syringe war
published in the Micrographic Dictionary which I will
qnote here ; — " We have therefore contrived a very simple
piece of apparatas, which any one can prepare for himself
and which effects the object by mechanical means. I
eists of a rectangular piece of board, two feet long and ten
inches wide, to one cud of which is fastened an inclined'

0? MICROSCOPIC OBJECTS. 183

piece of wood (eqnal in width to the long board, and one
foot high). The iachned portion is pierced with three holeg,
one above the other, into either of which the Hyriuge may
bo placed — tlie appermoat being need for tho larger, the
lowermost for the emaller syringe ; and these holes are of
inch size as freely to admit the syringe covered with Sannel,
but not to allow the rings to pass throngh them. The
lower part of the syringe is supported upon a semiannular
piece of wood, fastened to the upper end of an upright rod,
which slides in a hollow cylinder fixed at its base to a small
rectangular piece of wood ; and by means of a horizontal
wooden screw, the rod may be made to support the syringe
at any height required. The handle of the syringe is let
into a groove in a stout wooden rod connected by means of
two oatgut strings with a smaller rod, to the middle of
which is fastened a string playing over a pnlley, and at tho
end of which is a hook for supporting weights, the oatgut
strings passing through a longitudinal slit in the inclined
piece of wood." When in use the syringe is filled with
injecting Quid, and passed throngh one of the three holes
which is most suitable. The object being placed so that the
pipe and syringe can be best joined, the rod and strings are
set in order, and a weight placed oa the hook. The stop-
cock must then be opened gradually, when the operator
will he able to judge whether the weight is a proper one or
not : if the piston is driven with any speed, there is danger
of injuring the snbjeot, and less weight may be nsed ; ii',
however, the piston do not move, more must be added.'

21. Such is the method recommended in the Micro-
graphic Dictionary, and perhaps it is as good as any
mechanical plan oould be ; but where the operator is wilUng
t« undergo the labour of performing all this with the band,
he has a much better chance of sncceeding, because the
pressure can be regulated so accurately, and changed so

L

181 FREPAEATIOK AKD MOCSTIBO

qoicbly when rcquiHite, that no mere machine can compete
with it, however well contrived.

22. When the beginner attempta to inject a subject, one
of his difficnltieB is fioding the vessel from which to
mence. Another coneista in diBtinguishing the arleriea
from the veins ; bat this ie parttj removed by nalnng B
longitadinal incision in the vesBel, and with a lilant thick
neKlle probing a little distance into the tnbe. The artery
will be found thiclier in the coating than the vein, and tb»
difference ia easily perceived by this mode of testing: the
vein is also of a bluer coloar than the artery. I saj' abovS)
a. " longitudinal incision " moot be made ; the reason for thii
ia, that an artery when cnt acroea contracts considerably,

is lost in the adjoining Bobstance ; but where the openiog
is made longit'iidinaU!/ all danger of this contractioa it
obviated,

23. The different systems of vessels are often injected
with varioos coloore, so that the4r relative positions,
may be shown more clearly. In some specimens, the vein!
are injected with white, and the arteries with red ; ii
kidney, the urinary tabes are often filled with white,
the arteries with red. Then, again, the liver affords tabel
for three or fonr colonra. Bot no written instructions on
this poiot can benefit the young student, and he mnst
content for a while to employ himself with single colours
nntiL he has gained the mechanical skill and the primary
knowledge which are necessary before he can make any
advance.

24. We will now consider the best methods of mounting.
injected objects. They must always be well washed in
water after they have been kept in any preservative liquid,
iisiug a camel-hair pencil to clean the surface if necessary-
Many parts when injected are in masses, such as the lungs,
liver, Ad,, of animals, and consequently sections of thew
must be cnt. For this purpose Valentin's knife is veij
con''enient, as the thickness can be regulated so easily ; bnf
where the injections are opaque, tliere is no need to have the

or Yicaoscopic osiects. 185

B very thin. Some few of tlis liiod undergo corapara-
tivelj little cbange in drying, ho that the section maj be
well washed and floated upon the glass elide in the plaoe
desired, where it will dry perfectly and adhere to it. It
mast then be moistened with turpentine and monnted in
Canada halsam like other objects. No great heat shoold be
need with these preparations, as it is very liable to injure
them; and some of the colours eeem to suffer a slight con-
traction when any great degree of warmth is applied. There
are many objects, however, which mnat be seen in the masa
to be Ttsderstood, and, indeed, lose all their form and beauty
'n drying, such as certain parta of the intestines, ito. These
mnst be monnted in finid, with the precautions noticed at
'a Chapter T., and for this purpose either Goadby's
flnid, the chloride of zinc solution, or spirit diluted with ten
parte of distilled water, may be employed. It is a good
thing, when practicable, to mount similar objects on two
separate elides, using different preservative liquids, and
tabing the precaution of marking each with the kind of
liquid employed. This not only serves as a guide to what ia
best for certain eubjeots, but if one is injured, there will
probably be a good specimen in the other.

2b. It may be here mentioned that many are now mount-
ing sections of injected subatBDces with the balsam and
chloroform before mentioned, instead of using balsam alone,
and consider that the labour is mnch lessened thereby.

".A description of that mode of injection which is most
generally employed baa now been given, but this is not the
only method of effecting oar object. A most iugenioue
process was invented by M. DqyBrs, requiring no artificial
warmth, by which many beautiful objects have been pre-
pared. Make a solution of bichromate of potash, 524 grains
to a pint of water, and throw this into the vessels to be
injected ; then take 1,000 grains of acetate of lead dissolved
'u half a pint of water, and force this into the same vessels.
A decomposition now takes place iu the vessels, and the
yellow chromate of lead is formed. In this decomposition.

186 PESPilUIlOS AKD MOUKTQiO

hoirever, the acetate of potasb also is formed and aa i
Halt haa an injurious action apoD the cells, Br. Goadb]
recommends nitrate of lead to be used, which preBerTB
rather tlian deetrojs them. He also advises the addition
of two ounces of gelatine dissolved in eight ounces of watto^
to eight ounces of the saturated solution of each salt; but
with this addition the hot-water bath would be required b
keep the injecting fluid liquid.

27. Many of these b.tb best tnounted in balsan, in tliA
same tnauiier as those made in the ordinary way ; whilst
others are beat shown when preserved in liquids, for which
purpose Goadby's fluid may be employed,

28. This mode of making iujectious with chromate of le
is deemed by many the best, especially where one colon*
only is employed. But it must be allowed that there is
little more danger of failure where two separate fluids a
used for the same vessels.

29. We will now consider the best manner of making
iran^aTeiii injections, which, for many purposes, poaaesa a]
undoubted advantage over opaque ones. But it must b
remembered that there are certain subjects to which n
transparent injection could be applied, as they are too thiol
when iu their natural state, and cutting would destroy tl
that beauty which is shown by the difierent parts in
Tslative adaptation. For those objecta, however, v
must be cat into aectiona to display their wonders, o
naturally thin — such as some of the finer tisaues, liTerft
kidneya, &c., — transparency is a great acquisition
enables us to nudoratand the arrangement of the veaast
more perfectly. Again, another advantage is the simplioifj
ot the process ; no hot water is needed with some
parations, either for the subject or the injecting fluid, i
runs into the minute vessels thoroughly and easily, whili
the cost is small.

30. For this kind of injection no colour is so con
used as Prussian blue. It is not a good one, as was
stated, for any opaque object, the light reflected from :

OP aicKoscopic OBJECTS. 137

appearing almaat black ; jet hy traiiemitted light no colour
IB more uBefuI, beeanae its distinctness is equally great by
artificial ligbt acd ordiDarj dajligbt. Tb.a method of pre-
patiDg this, as given by Dr, Beale, ia as foUoira: —

Glycerine 1 oonce.

Wood naphtha, or pjroaoetic acid 1^ drachm.

Spirits of wine 1 ouQce.

Ferrocyanide (yellow pmseiate) of potas-

Bium 12 grains.

Tinctaie of seaqnichloride of iron 1 drachm.

Water 4 ounces.

DisBolve the ferrocyanide of potassiam in one onnce of the
water ; add the tincture of aesqoicbloride of iron to another
ounce. Mix theae solutions gradoally together, shaking tho
bottle well which contains them — it is beat to add the iron
to the potaah solntion. When thoroughly mised, these
Holntions shontd produce a dark -bine mix tore, perfectly
free from any perceptible masses or flocculi. Noit mis tho
naphtha and spirits of wine, and add the glycerine and the
remaining two onncea of water, Thia mnat now bo slowly
mixed with the blue liquid, shaking the wliole well in a
large bottle whilst the two come together. The tincture of
sesquichlorido of iron is recommended, because it can always
be obtained of a uniform strength.

31. Dr. Torobnll ased a mixture slightly different from
the above, nhich is made with the sulphate of iron: —

Forified snlphate of iron 10 grains.

Ferrocyanide of potaaaium 32 grains.

Glycerine 1 ounce.

Fyroacetio acid 1^ drachm.

Alcohol 1 ounce.

Water 4 onncea.

Ilissolvo the sulphate of i

of the water.

188 rEEPAEiTIOK iS& KOCSTING

gradually add the ferrocyanide of potaSBinm diasolved
an-other ounce, and proceed aa before.

32, Dr. Benle altio gives ua the following carmine injection
to be employed ia the same way as the blue.* Take —

Carmine b grains.

Glycerine, with 8 or 10 dropg of hydro-
chloric acid i onnce.

Glycerine (pure) 1 onnoe.

Alcohol 2 droohme.

Water 6 drachinB.

Mix the carmine with a few drops of water, and when well
incorporated add about fire drops of liquor ammonia ""
this dark-red aolotion abont half an ounce of the glycerins
ia to ho added, and the nhole wull shalcen in a bottle.
Neit, very gradually pour in the acid glycerine, frequently
Bhaking the bottle during admixture. Test the mixture
with blue litmus-paper, and if not of a very decidedly acid
reaction, a few more drops of acid may he added to the
remainder of the glycerine and mixed as before. Laatly,
mix the alcohol and water very gradually, shaking the botUa
Ihoronghly after adding each successive portion till the
whole is mixed. This fluid may be kept ready pieparedi
and iujeotioDs made very rapidly with it.

33. The method of mating injections with these colonra
ia the same as with the gelatine mixtures before described,
except that no heat is required, and consequently most of
the trouble removed. The bottle of the diiid must be well
shaken immediately before use ; and when the object has
been injected, we mnst allow it to remain in a cool pli
a, few hours before cutting it. Thin sections of the snbjeat
may be cut with Yalentin'a knife, as before described, and

' When, however, It is desirable to out very thin aeotions of Iht

g;etatiTie — gelntiDe ODO part to water ei^ht parts. But the wariu ^umv
and mode of riroceediuf- which are used nitb the «zo Bolutions befoM
deaeribed nil] be uecBBsarj iit tbie oase also.

OF UlCROSCOnC OBJECTS. 189

B very beantifnl transparent objects. Some of the finer
tissaes, also, are Bhowa much better by tbiE mode of in-
jection than by tbe opaqae, and ara easily mounted bj
nashing in clean water wben first separateJ, and fioating
Dpon a slide, where they mast be allowed to dry thoronghlj.
They may then he immediately monnted in balsam, or kept
' 1 ^e dry state until it is convenient to finish them ; bat

I many cases this kei?ping, if too mach prolonged, will
injure the object. If it is desired to transfier the eectioD to
another slide, it will be necessary to wet it thoroughly with
water by the aid of a oamel-bair pencil, and then gently
Htiip it off with the forceps. When it is wished to preserve
injected subjects in masses, it must be done by immersion
in spirit, and the sections may be cut at leisure. Most of
these transparent objects may be mounted in Canada
' alsam i bnt some recommend glycerine or glycerine jelly,

s allowing the use of a higher power in their examination,
and preserving them in a more natural form.

34. A few snbjects may be noticed which are very beauti-
ful when injected, and amongst these are the eyes of many
lals. They mnst be injected by the artery in the back
part, and when the blue transparent liquid is employed,
nothing can e*:ceed the delicate beauty displayed by some
of the membrane. It mast be dissected with care, but well
repays us far the tronble, Water-newts and frogs are not
diEGcalt subjects, and in their skin and other parts are many
interesting objects. Amongst the commoner animals — rats,
rabbits, cats, &c.— almost endless employment may be
found, making use either of portions or the whole animal at
once. The intestines of many of these are very beantiful.
We mast divide them with a pair of scissors along the tube,
snd cleanse them from the contents ; the specimen may
then be laid upon a qlide, and any remaining impurity
removed by a camel-hair pencil and water. When dried it
nay be mounted in balsam, and having been injected with
the transparent blue, its minnte beauty ia shown most per-
fectly. In injecting a sheep's foot, which is a good object.

1!X)

the liquid Bhouid be forced into it ontil a sliglit panng of
the boot shona tbe coloar id the fine chaDO^ there,
Perhaps one of the most beantifnl and iutcrefiting objects is
the akin or section of a cat's tongue. On eiaminstion ws
Bhall readi); learn tbe reason wb; ne feel such a
when ne aKon the cat lo applj her tongne to oar basdo.
Id appearance we ahatl be almost readj to eaj that there i>.
no little resemblaDce in tbe arrangement betwiit this tongaS'
and those of the mollDsce atread; described. The liver of k
rabbit or anj other animal is an easy and beautifa! objeot
for injection. Sections made with Yalentin's kaife, and.
mounted in balsam, are not at all difficult, and worth donbia
the time thej occupy.

35. When tbe lungs of email animals are injected, the
fioest £nid must be nsed, as some of tbe capillar'
small that it is not an easy matter to fill them properlj,
And before entering upon these subjects, a certain pro-
ficiency in the mode of using the syringe, &c., ahoold be
obtained by practiatng npoo simpler parte.

3(). No subjects are more difficalt to inject than fisfaj.
owing to the extreme Boftneas of their tiaaues. Mr. Hogg
recommends the tail of the fish to be cut off, and the pips
to be pat into tbe divided vessel which lies jast beneath Uie
apinal colnran ; by which method beautiful injections maj
be made. The gilla, however, are the moat interesting part
as microaoopio objects.

37. These inatructiona may seem very imperfect to those-
who have bad much experience in tbia brajicb ; bat thiiy<
will rememljei- that their own knowledge was not gained
from any written descriptions, but was forced npon them
by frequent failures, some of which probably were very dis-
heartening. As I before stated, it is very difScnlt (^ not
impossible) to accomplish much without soroe knowledge of
anatomy,

38. I may here mention that tbe transparent injeotions
Bent over from tbe Continent are beautifully executed by-
Hyrtl of Vienna (who atates that the iojectei flnid is

OF Micaoscopic OBJECTS, lU;

posed of gelatine and canoine), Dr. Oscliatz of Berlin,
the Microscopic Inatitnte of Wabern, Schafier and Co. of
Magdeburg, and others. Some of these will bear eiamiaing
with a high power, A friend informa me that he measnred
ft vessp.l in a rat's tongue by Hjrtl, which was l-(200th
of an inch in diameter, and had a clear outline with quarter-
inch objective. He baa also made many experiments with
the same materials, bnt has aa yet failed in producing
perfectly diatinot outlines, there being a tendency of the
colouring matter (magenta, carmine, &c.) to diffuse itself
thlMUgh the coats of the vessels into the snrronnding tissues,
although he has varied the pressure from half a pound to
Biity poan^s. He believes the vessels are first washed out
(injected with warm water and pressure applied), then some
fluid introduced, probably solatioo of tannin, which renders
the arteries imperviona to the coloured fluid afterwards in-
jected.

39. He finds that after washing oat the vessels as above,
the injecting fluid is much more easily introduced. He liaa
used a strong solution of gallic acid previonslf to injecting
with the colooring matter (ia one experiment only}, and the
result was satisfactory. He puts the query, — Might aot
carbolia acid have a similar eSect P He has often used it
with injections to preserve the specimens, but not in saf-
ficient quantity to act in the way indicated above,

Binoe writing the above, Mr. J, G, Dale, P.CS,, and I
have made namerons experiments with carmine injection,
and have at length been favoured with what we deem
anooess. Some of the vessels in a kitten lately injected do
not exceed l-'2000th of an inch in diameter, and present a
clear outline with one-fifth objective. There is no extra-
vasation, neither does the colouring matter show any grain
except when a very high power is employed. The following
r process ; —

raEFiEATios J

Take leO grains best carmine.

i fluid ounce of ammonia, commercial etrengtlii

viz., 0'92, or 15° ammonia meter.
3 or 4 onnces distilled water.

Pot tbese into a. small flask, and allow them to digest with-
oat beat from tweoty-fonr to thirtj-si: boars, or nntil tlie
carmine is dissolved. Then take a Wincheat«r qaart bottlt
and with a diamond mark the spot to which Btiteen onnceR
of water eitend. The colonred aolntion must be filtered
into the bottle, and to this pore water should be added
until the whole is equal to sixteen ounces.

Dissolve tiUO grains potash alam in ten floid
water, and add to this, nnder constant boiling, a solution of
carbonate of soda nntil a slight permanent precipitate is
produced. Filter and add water up to sixteen onnces. Boil
and add the solution to the cold ammoniacal solution of
carmine in the Winchester qaart, and shake vigoronslj for
a few minntes. A drop of this placed apon white fitteriog-
paper should show no coloared ring. If much colour is in
Eolation the whole must be rejected, because, although
it is possible to precipitate all the colouring matter by
the addition of ammonia or alnm, it is not well to do
so, as tbe physical condition of the precipitate is therebj
altered.

Sappoaing the precipitation to be complete, or yery
nearly so, shake vigoroualj for at least half an hoar, and
allow it to stand until qaite cold. The shaking mnst then
be renewed for some time, and the bottle filled up with pure

After allowing the precipitate to settle a day, draw off
the clear supernatant fluid with a sjphon, Bepeat the
washing nnlil the clear liquid gives little or no precipitate
witb chloride of barium. So much water mast ha left.
with the colour at last tbat it ehall measure forty flaid
ounces.

Of MicKOScopic OBJECTS. 193

For tbe isjeotiog flnid, talie 24 onnces of the coloured
liqaid thae prepared, and three oaacea of good gektiDe.
Allow these to remain together twelve hours, and then
disBolve bj the heat of a water-bath ; after which it ehould
be ttrained through fine muslin.

Ab this injecting fluid cautainH gelatine, the hot water,
and other contrivanceH mentioned in a former part of the
chapter, will be Deceasar; here also, bat no pecoliar treat-
ment will be required.

6 writing the above concerning carmine injection, I
hare had the miefortune to lose mj friend Mr. Dale, but not
before we made scores of experiments together, with this
formula. Oor experience, I may say without vanity, joati-
' 1 declaring that a good operator can get resolta
aqoal t^i any that he will receive from the Continent, as far as
coloDT and dietinctnesH are concerned. The colour, being
thorongbly precipitated, cannot stain the tissues, and the
conrae is thns clear and well deSned. If the object is small,
■■ "s well to use the mixture with 25 or 30 ounces of water
instead of 40 ; but, with this exception, I know of nothing
that needs alteration. I have, time after time, measured
Teasels thoroughly filled with good colour — especially
amongst fatty portions, — and found them betwixt l-3000(Ji
Hud l-400Oth of an inch. As some young students might
" Give me an account of something done with it," I will
endeavour to describe my nse of part of a horse's leg. My
frieod Mr. Hepworth wrote to me that he had a horse's leg,
and should be glad if I would come over with sufficient car-
mine t4> inject it. I tooh three pints of solotion, and may
here mention that, with a very slight loss indeed, all this
liquid was thrown into our subject. The leg was cut off
just beneath the knee, and before using it we allowed it to
in water about 80° or 90° Fahrenheit two or three
md then introduced onr syringe into an artery at
the top. As I have no faith in any mechanioal contrivance.

1ft* PREPAHATION AND MOUKTIKG

I nfied the comnion BjriDge, and Glled the leg with t
liqaid. We then placed it in cold water, and allowed it t<
remain nntil the next morning.

The first work was to remove a piece of the Btin, ai
take Beutions of it hy the aid of a Yalentio's knife. Thttl
arteries were iihown beantifullj -, bat the most attractiTS
part was where the growth of the hair was laid open before .
as. Each hair exacll; resembled a common onion, whil;
every bolb was snrronnded bj a perfect network of arteriet
and where any bnlb had been torn oat by accident, iheu
was left a niinnte bird'e-nest of them, clearly showing boi
they bad been intertwined aroood some lo»t friend. Dif<
ferent sections of the majcolar portions showed every pbaa
of arterial distribution, with some eiqnisitely minate veseeb
in parts. I then took an artery and cut cross sec
wbich the carmine portions were as closely interwoven ■>
wickerwork. I also, with a pair of scissors, laid open k
length of the artery, and mounted it, together with a eras
section. In the same way I Deed the Teins. Many of tfa
nerves we took out, and, after cleauiDg carefully with knin
and small brushes where necessary, mounted them wift
the attendant arteries around them. But as we approacba'
the hoof, double interest was given us. The skin with itahan
jnst above the hoof plainly showed the change taking plae%'
and sections of the hoof gave beantifol specimeDS of who*
oircntatiou was gradually stayed by the growth of hardor
substance. Here, too, we reached the Umiofe, or tiM
plates (somewhat resembling the gilla of certain
the exact nse of which, we have no space to discnss — mai
these were readily removed by the aid of scisi
knife. In these the vessels are minutely and eiqunU^
Bbown.

These are a few of the beauties which tbia injutil
kfforded me. My friend Mr. Hepworth and I worked li
gether at this aobji^t for a week or two, and pw~ * **
knowledge wbicb he gained from it waa cammaniMted I

OP MICROSCOPIC OBJECTS. 195

the microscopic world in tlie fifth volume of their Joarnal,
where the illnstrations are beautifully printed. We took
about 1,000 slides from this leg, but could easily have taken
a specimen for every microscopist in the country. What
few slides I now have are mostly mounted in balsam, and
are quite as good in colour and every way as beautiful as
on the day they were mounted.

o2

rmn-AUTKn axd

CHAPTER VIII

It mnat be evident to all readers that there a
objects of intereet to the microicopigt which caonot b
properly placed amongst any of the faremeotioned cIb£
bat moat not be omitted in such a gnide as this
to be. Of these may be mentioned the circulation of U
blood in varioas animals, the rotary motion of the Soil
in tnacy plaats, the beat means of taking minate phoiB
tograpba, &a. &a.

Perhaps the most interesting of these objects ia
lation of the blood through the finer TeBsels of var
of animats nsed for these parposos, which parte, it ia evidenta
most be very tranaparent to afford a perfect view of thi
phenomenon. The web of the frog'a foot is very freqneDtHIJ
employed, hot requires a certain arrangement, which n
now describe. A piece of thin wood (Dr. Carpenter r
mends cork) is taken, about eight inches long and thraij
wide ; about an inch from one end ia cat a hole, half CB
th red-quarters of an inch in diameter. The body of ti
frog ia then placed in a wet bag, or wrapped in t
whilst the hind foot projecta ; tlic whole is then laid u
tbe piece of wood, so that the foot, which ia left free, may b
oxteuded over the hole. Tbs web moat then be spread ona
Kod secured, either by loops of thread fastened to lite b
and attached to small pins placed around the hole in the <
or the pins may be inserted into the wood — Ihrongh t
ireb. A few bands of tape mnat be passed round t
body, the Ivg, and the wood, to prevent any diaarrangemi
nriHJDg from the struggles of the aDtmal. Care ronst II

ECTS. 19?

I taken that the tape be not too tight, else the circulation will
be verj slaw or altogether atopped. The wood rnust now be
fixed npoD the stage, with the aperture under the object-
glass : this is Bometimea done bj Bimplj binding it, or a
Hpring is Sued ao as to aucomplisk the same object without
inch trouble. With a half-inch power the blood may
be seen to flow very distinctly. The frog may be used for
hours if care be taken to prevent the web from becoming
dry, by wetting it with a little water from time to time.
The piece of wood or cork upon which the frog is laid is
often made to give place to the " frog-platea," supplied by
lus. These are made of brass, somewhat resembling
iece of wood above recommended, but each maker's
pattern differs, according to hia own taste.

The tongue of the frog is also eometimea nsed for the
purpose of showing the circalation of the blood, which is
done io the following manner ; — The body is wrapped with
ealieo, and made faat to the plate as before, ooly the inouth
of the frog is brought to the opeDing. The tongue is then
gently drawn out of the mouth and pinned down over the
aperture, when the circulation will be well shown. But, as
Dr. Carpenter obaerveB, the cruelty of this mode of treat-
ment is BO repulsive tbat it is unjuatiflable.

Tadpoles of the frog (which, of eoarae, are only obtainable
a their season) are good subjects for showing the circula-
tion of the blood. They are best suited for the microscope
when about one inch long. The tadpoles of the newt and
toad also are equally suitable. They may be placed in a
very shallow glass trough with a little water, and a narrow
band of linen bound lightly round in some part not required
I, to keep them from moving ; or they may
be laid upon a glass plate with a drop or two of water, and
a thin glass covering lightly bouud upon it. Dr. Carpenter,
however, places them hrat in cold water, gradaally adding
1 until the whole becomes about 100", when the tadpole
lies rigid, whilst the circulation is etiU maintained. I
have not, howeTsr, fouud this neoeaaary, the thin glaea ao-

complisUog all that is desired. The tail is generally tl
nofli tracBporeiit, and abowa the circalatian be»t ; but '
some of the newt larfte the blood may be traced down
the lery eitTemitiea jf thej are not loo old. Mr. Whitne
places tbe tadpole upon ita back, bj which meaos the bei
and other internal arrangements maj be seen.

AmoDgflt fishes also maj be foaud enbjecta for the sa
pnrpose, but they seldom fnniish socb good examplea
thoee before mentioDed, becanse the blood-vosBels are i
nearlj so ahnndaot as in the foot of the frog, &a. 1
aticklebaek ia, however, procorable almost in any pli
daring the summer nionthg, and maj be laid in a shalloi
trough, looael; boond down as the tadpole. The tail
be covered with a piece of thin glass to prevent him cnrlinj
it to the objcot-glttSB. The power needed for this will ~
abont the same as with the other sobjects ; tjz., a, half
a qnarter-iDch object-glass.

It is Dot absolntely necessary to go to reptiles or fisi
for this corious sight, as some other animals serve Ti
well. In the wings of the common hat may be found
good sobject. Tbese mast be slretohed ont on somethi
resembling tbe frog-plate before described, when those pal
near to the bones will show the InrgeH vessels very cli
The ear of a yoocg moose is an illustration of the
phenomraon, but it ia very dtl&cnlt to fix it in a
position, as these animals are so very timid aod restless.

Amongst insects also the circulation may be seen
placing them in the cage, or live-box, ho as to keep thi
still, but not to injure them by too much pressure,
certain larvaj it ia particularly well shown, aa in those of t
day-Hj and plumed goat ; but in some of these the blood
almost colourless. In the wings also of many insects thii
circulatioo is well seen, as in those of the common housefly J.
but as these parts become dry in a few daya, the aubji
shoold not be more than tnenty-four hoiiTs old,

Somewhat spproiimating to the fore mentioned pheni
menon, is the rotation (or cyclosis) of .fluid in the cella.

or MiOBOScoric OBrecis.

as it IB nsnally termed, the ciradattoii of the sfip, of plants.
Thia is ahoiTD in certain vegetable growths as a. constaat
Btreain of thiuk fiuiJ, wherein amall globules are seen ;
which atream flowa round the individual cells, or up the
leaf, tarning at the extremitj, and down again by a different
bnt parallel chanuel. There ia little or no difficultj in
ahowing this in many plants ; bat some a.re, of coarse,
better than others, and require a different treatment; we
will, therefore, notice a few of these. Perhaps the best of
all ia the Vailistieria a-piralts, which is an aquatic plant,
frequently grown in, hat not really belonging to, this
ooantry. As it aomewhat reaemhiea grass, the leaf is not
□Bed in its natural state, but a thin section cat lengthwise
with a razor or other sharp inatrumenti thia section, how-
ever, is moch better when the outer surface has been first
remoTed. It should then he laid upon a slide with a drop
or two of water, and covered with a piece of thin glass.
OfteOi the cutting of the section aeems to be such a ahock to
the leaf that no motion is visible for awhile, bat in a short
time the warmth of an ordinary sitting-room will revive it,
and with a quarter-inch object-elasa the ourrents will be
rendered beautifully distinct. Where the stream is nn-
naaally obstinate, the warmth may ba slightly increased, bat
too high a heat destroys the movement altogether, In the
Bummer, any of the leaves show this circulation very
well) but in the winter, the slightly yellow ones are said to
be the best.

The Tallisneria requires to be cut in sections to ahow
thia circulation ; but there are many plants of which it ia
bat necessary to take a fragment and lay it upon the slide.
The Av-ftcharie ahhwateum, ia one of these : it grows ia
water, having three leaves round the stem, then a bare por-
tion, again another three leaves, and so on. One of these
leaves must be plucked close to the stem, and laid upon a
alide with a drop of water. Thin glass should be placed
upon it, and along the mid-rib of the leaves the circulation
may be seen most beautifully when a good specimea has

200 paeriiuTioN a

been chosen ; tot it reqaires rather more power than t
Vallisneria. This plant ia very comnion in many parte
the conntry, a S'eat number of our ponda and atreame b '
literally choked np by it. In the Clmra vvlgnris and two O
three of the Nitcllie, &c., this phennmeaon may also be n
with no preparation except plucking a part from the at
and laying it npon a slide, as with the Anacharis, In qbi
the Frog-bit, the onter part of the yonnj? leaf-bada most I)
taken to obtain the beat specimeng for this purpose; bati
section of the stem will also ahow the circulation, thongh ni
so well. Tbe plants before meutioned are all aqnatic, b
the same movemeut of the globulea has been observed i)
several kinds of land plants ; as in the hairs npon the 1(
stalks of the common groundsel ; but these do not show I
80 well, nor are they so easily managed aa the preceding.

Many microscopista who are not fortonate enough to i
in the neighbourhood of these plants (indeed the ValUsnen*
is a foreign one) grow tfaem in jara ; BO a few remarks as
tbe treatment they require will not be out of place. T
Vallianeria requirea a temperature not lower than 55°
60°, and even a higher degree than this renders its growti
qnicker; and no great change maat take place : the mo(
equable the temperature the more healthy will the plant b9
A glass jar should be taken, having an inch or two of m
at the bottom, which must be pressed down closely, and tl
plant must be aet in this. Water must then be gent^
ponred in, so as not to diatitrb the mould. As this plat
flourishes best when the water is frequently change^
Mr. Qaekett recommends that the jar should be ooaasianafl]
placed under a tap of water, and a very gentle b(
allowed to fall into it for several hours, by which i
innch of the confervoid growth will be removed and tbi
plant invigorated. The Anacharis may be i
earth like tbe Yallisneria, but a small detached piece may b
thrown into the jar of water and there Itft nntil want«d
For months the circulation will bewell shown by it, and it w3
probably grow and increase. It is also very healthy ii

OP MICROSCOPIC OBJECTS. 201

1-door aquariam. It is reoommended that the jara ia
which the planta of Chara are grown shoald be moved alioafc
BS little as poseible, as the long toota are very tender, and
will not hear agitation.

An ohject which ia interesting to the microacopist, as
well aa the nnacientiSa observer, is the growth o( seeds, as it
ia often erroneoualj termed. A ahaving of the outside of
the seed ia taken and laid upon the glasa slide ; a thin
glass cover is then placed upon it, and a drop of water
applied to its edge. The water will gradually flow nnder
the glass and reach the section of the seed, wben transparent
fibres will appear to epring ont and " grow " for some
roioates. This, however, ia produced bj the unfolding of a
spiral formation in the cells, and, therefore, haa really no
aimilaiity to the true growth. The seeds of the Salviaa,
Gollomia^, Senecio, Buellia, &c., are well snited for the
displaj of this curioaa sigbt.

To wateh the development of the spores of ferns, and the
fertilization and produota, Dr. Carpenter recommends the
following mode of proceeding: — "Let a frond of a fern,
whose frnctilication is matnre, be laid upon a piece of fine
paper, with its spore-bearing- surface downwards ; in the
course of a day or two this paper will be found to be covered
with a very fioo brownish duat, which consiata of the dis-
charged spores. This must be carefully collected, and
should be spread npon the aurface of a smoothed fragment
of porous sacdetone ; the stone being placed in a aaacer,
the bottom of which is covered with water, and a glass
tnmbler being inverted over it, the reqniaite supply of
moiatnre ia inaured, and the sporea will germinate luxuriantly.
Some of the prothallia soon advance beyond the rest; and
at the time when the advanced ones have long ceased to
produce antheridia, and bear abundance of archegonia, those
which have remained behind in their growth are beginning
to be covered with antheridia. If the crop be now Icept
with little moisture for several weeks and then suddenly
watered, a large namber of antheridia and archegonia

nUiie «ti«t to tiN 7««>g ■
■■■iii hf thm ipoiH «f Aa EqMta (or
Iktf an aAca iiHni) TkM *■; W abUiMd by ai
Ifce U^MT perlioa eftW rf— wWm tW spores sre i

TWr «B Uca bn ia» mmD Ami, ud maj b« ]
rader tke ^otweope. The iporca are tiua a
of » ■ommrbat fatwi-db^wd nMs witli bonds niher iiti
tneatclj ewted aroand it. A» 0107 dry, tLese I
expand, and ar« aeen to bs four lines at right angles, *■
the enda clobbcd, as it majr be called. If, whilst watohingl
iixtto, the spores are breathed apon, theae bands im mediately I
retain to their funner state, and are closely corled atound I
the apore ; bat as tbey gradaallj drj, again eipand. This f
eiperimenl may be repeat^ many times, and is a. very I
ioteresting one. I

The preceding are the priocipal objects which could Dot 1
poaeitily be included in any of tbe former chaptera, bat I
noald have left a most interesting branch untouched had HM
been neglected. There is another subject, also which should I
not be pasaed by ; via., the production of minnte picturefl I
wbich serve as objects for microscopic ei:amiDBtioQ.
mny here mention that as tbia manual is simply I
uiiublo the student to prepare and mount his objeote, the 1

OF uicEoscortc osjEcis. SOS

photography of magnified objects Las e?identlj do place

Few alideB canaed so mnch astonishment aa those minnte
photographs when first exhibited ; small epota were seen to
contain large pictnreB, and a page of printed matter was
compressed into the one-hondredth part of a aqaare inch.
It would be imposaible in this place to gi?e the inquirer
any inatrnctioa in the manipulation of f>hotography, ao it
mast be assumed that he already knows ibis.

We will first consider the process performed bj artificial
light. The collodion employed in photographing generally
shows aa mach stracture when nagoified as is found in
linen of looderate textore ; bnt this is not always tbe case,
as some samples bear mach enlargement without any of
this appearance. It is evident that a atructnre so coarse
would make it entirely nnfit for these minute pictnreti, aa
all the small markings would be destroyed, or so interfered
with, that no great enlargement would be practicable. To
obtain almost structnreleas collodion is not an easy matter,
and a clever practitioner in this branch of photography
states that he knows of no method to accomplish this with
certainty, but he himself tries different samples nntil he
falls upon a suitable one, wbiuh he then lays aside for this
object. A beneficial effect is often derived from keeping the
collodion awhile, hut this is not always the case. The slides
should be chosen of an equal thiclness, so that vhen
focuBsed upon one, no re -adjustment may be necessary for
the others. The glass ahotild, of course, be free from any
TOughneBB, scratches, or other imperfections, and of Tery
good quality and colour.

The microscope must be placed in a horizontal position,
and the eye-piece removed, the stage having a small clip
npon it to keep the prepared plate in position. The nega-
tive mnst be supported at a distance from that end of the
microscope tube from which the eye-piece was withdrawn.
This distance will, of course, vary according to the relative
sizes of the negative and desired picture. With an inch

204 vaePABiTios asd stonsTiso

(ilijuct-giMB, wbioh is of averj conventeDt fooDEi, it will vaij
unnall; betniit ODe and foar feet. The negative most bt
lighted by an argaod gas-burner or oamphine-larap, and the
rajB rendered aa parallel aa possible by a large plaoo-con»(
lane placed betwiit the light and the negative. Iti«ii<
easy to arrange the apparatna ao as to get the light un
/ifr-ni ; but a little practioe will soon obviate thia difficnlty.
Ordinary groQad-glaae is too coaraeiy grained to focns npoa,
aa the magnifying power used to examine the minate reflee^
tion most be conBiderable. One of the elides must therefore
be coated with collodion, aabmitted to the ailver-bath, oi
ahuT waahing with water, allowed to dry. Upon thia insjr
be foouaaed the reflected image, and its minateceaa examined
with a powerful hand-magoifier, or another microBoopi
placed behind in a horizontal position. Whea the ntmiMt
eharpneaa of definition is obtained, it is naaallj necessary t(
remove the plate a little distance from the object-glass, M
those for the microBoope are slightly over-corrected, so that
the chemical raya which aaeomplish the photography w
beyond the visual ones. The exact distance required to
give a piotnre to show the greatest diatinctness cannot bs
given by rale ; but eiperimeata mnst be made at first, and'
it will always be the same with the object-glass which w
have tested.

The plat« may now be prepared as in ordinary phot»-L
grapby, and placed upon the stage whilst the li^t a
•haded. When all is ready, the shade is removed and lkl|
process allowed to go on, nanally for thirty or forty Moondi
bat no certain rule can be given as t« the required time, ai
acconnt of the variety of coltodionR, lamps, and paweni N
It may be here mentioned, that it is well to c
little frame to receive the prepared plat«, as tl
aolntion is liable to get npion the microscope-si
to say the least, disfigare it. When the e
oontioned safficiently long, the pictnre may be <
any of the onlinary methods, bat some of the
tions have been brought ont by the aid of pyro

OF HICKOSCOFIC OBJECtS. 205

oitric acid solution, nitli tbe addition of a little alcoliol.
The filing ta&y be effected by a strong solation of bjpo-
snlphite of soda, and the picture should then be very well
washed with pure water. When drj, the photograph must
be monnted nith Canada balaam, in the same manner as
any ordinary object; bat great heat moBt not be Dsed, or
the picture may bo injured.

When ordinary daylight is employed for this purpose, a
dart slide will be reqnired for the prepared plats, in the
Hame way as for photographing landscapes, &o. These
dark slides are generally made by each indiTidual to suit
hia particular arrangementa of negatives ; but it may
ba here recommended that the operator shonld always
focus in the same slide which he is about to use, as so
small a dli^erence in distance lies betnlxt perfection and
failnre.

For an ordinary student, perhaps the preceding method is
that which is the most readily used, and consequently the
most generally available; but almost every one baa a dif.
fereut arrangement of microscope, by which he procures
these minute pictures. !U!r. Shadbolt (one of our most
BuocBasfa! photographers) gives the following iastructions: —
"Haviug removed the upper stage-plate of a large oom-
pound microscope, I replace it with one of wood, supplied
with guide-pins of silver wire, in order to admit of its SDp-
portiug a slip of glass coated with collodion, and excited in
the nitrate of silver bath in the uauat way. If the ordi-
nary brass stage-plate were left undisturbed, it is obvions
that it and the excited slip of glass wonld be mutually
destructive.

" The microscope is now to be placed in a horizontal
position, the objective, intended to produce the picture,
made to occupy the place nsoally £Oud by the achromatic
condenser on the suh-etoge of the microscope, while another
objective is screwed into the lower end of the body of the
instrument, which is used not only to focus with, but^also
to make the requisite allowance for actinic variation.

■ MgktiTe intotded to be redaced is tlioi Kirai)]^
rertkallj, «iUi its centre in tbe am of the mirroec^pie
bodj, *t k dutuice from two to foar fiwt ham the lower*
a b ject g l—», and wila a coDTCDieDt tcreea of cftrd, wood, of
■per, to cot dff any eitr&neons light that woo"
e pati bejond the limits of the pictare-
nuU cam phine- lamp ia emplojed for the parpoae
minating the negatiTe. hariiig a good baii's-eye lens
■ eondcuKT, ao arranged with its flat side next the lamp
that the refracted rays shall just fill the whole of a donbla
convex lens of aboat >ii iocbes ia diameter, the latter b
pla<Kd in HDch a position as to refract tbe rajs of light
p«nllel direction upon the negative. Bj this arrangement
tbe tndCt-eye lent of aboat two inches and a half in
diameter appear* as the source of the light instead of ths
small flame of the lamp.

" By nsing a bat's-wing gas-bnmer of a good aize, a »ui^
lens, instead of the two, may be BO placed as to gifo thS'
ueeesaary nniformity of illamioatioa."

This arrangement requires the same care in working aa
that before mentioned, the pictares beiog produced, de-
Teloped, and fixed by the same treatment.

It is certain that almost every manipnlutor malces some
email changes in the method of prodocing these minute pio-
tnrea ; bnt the roles given, thoagh far from new, are
Bofficieot for all pnrposes ; and I may say with truth, that
those which I procured when these wonders were quite new,
are folly eqnal in every respect to the beat usually met with,
at the present time.

With these inatrnctiouB I shall close my Handbook, as I
heliere that nearly every branch of tbe Preparation and
Mounting of Microscopio Ohjects has been treated of. Hot
that the beginner can expect that ho has only to read this
to be able to mount everything ; hot that there are difficul-
ties from wbicli he may be freed by instruction, when other-
wise he would have been compelled to learn by failure alone.
I may here, however, repeat certa.in advice before given,-

OF MICROSCOPIC OBJECTS. 207

tbat, when practicable, it is a good thing to mount each
object by two or more diflferent methods, as very frequently
one feature is best shown dry, another in liquid, and a third
in balsam. Secondly, let no failures discourage you in
following up what will assuredly one day become a source of
great pleasure, and render your daily constitutional walk,
which is often dull in the extreme, very delightful, as it will
afford you some new wonder in every hedge-row. And,
lastly, let the mounting be studied thoroughly, scarcely any
part of microscopie science being more worthy of thought
than this, since it will so far contribute to the enjoyment
or instruction of others, as to preserve for their examination,
objects which have already ministered to your own, but
which may yet be so perishable as to be speedily lost unless
some one of the many processes described in this manual be
employed for their preservation.

IMDKX.

209

INDEX.

A.

VAOB

ACABIDA 110

Acid, acetic 5

Acid, carbolic ....^ 127

Acid, chlorhyd 5

Acid, hippuric 114

Acid, hydrofluoric 19

Acid, hyperosmic 9

Acid, nitaric 5, 61, 62

Acid, nitric, with chlorate

ofpotash 6

Acid, oxalic 6

Acid, phosphoric 5

Acid, sulphuric 5, 11

Acid, tannic 5

Agents, "differentiating"... 5

Agents, hardening 9

Agents, softening 13

Agents, staining 7

Air-bubbles 42

Ait-bubbles, to expel 91

Albumin 16

Alcohol 5, 6. 9,17

Algse and desraids, to pre-
serve 127

Algae, to presenre 125

Ammonia 6

Ammonia, molybdate of 7

Ammonia, oxalurate of 112

AmmonisB, liquor 14, 67

Anatomical roecimens, Bru-
netti's mode of preparing 164

Aniline colours 7

Animal tissues, dissection of 163

Anise, oil of 7

Antenna 107, 137

Antennsd, to bleach 107

Asphaltum 45, 49

B.

VAOB

Balsam and Chloroform 44

Balsam, Canada 7

Baiyta water 6

Bath for injections 177

Bath, hot- water, cheap 93

Beaker glasses 65

Benzole 17, 19

Benzole — Benzine 75

Berg-mehl 72

Blights 87

Blood-discs 83

Blood-stains, to detect 84

Blue, Prussian 8

Boiling 11

Bone, chips of, stained 149

Bone, sections of 148

Bones, fossil, sections of ... 150

Bones, softened 15

Bottle-washing 76

Brain and spinal cord, sec-
tions of 166

Breeding-cage for podur»,
Mclntyre's 83

C.

Calcareous matter, sol-
vents of 18

Camphor 20

Camphor- water ... 13, 123

Canada balsam 43

Canada balsam and benzole 90

Carmine solution 7

Casein 16

Cassia, oil of 7

Castor oU 19, 127

210

n^DEX.

PAOB

Castor oil, to mount crystals

in 113

Cells, built up 129

Cells, brass 31

Cells, of card 29

Cells, epithelial 7

Cells, how to fill with balsam 95

Cells for test objects 32

Cells, ivory 81

Cells, leather 30

Cells, paper 56

Cells, pill-box 31

Cells, Piper's 31

Cells, tin, zinc 31

Cells to fill 132

Cells, wooden 29

Cellulose in coal 144

Cement cells 54,128

Cement, Dr. Bastian's 129

Cement, electrical 46

Cement, Marion 47

Cements 43

Cerebral tissue 13

Chalk, organisms in 98

Chamber, moist 22

Chondrin 17

Chromic acid 9

Circulation in Anacharis and

VaUisneria 199

Circulation in foot and tongue

of frog, to see 196

Circulation in insects 198

Circulation in tadpoles 197

Clips, spring 41

Cloves, oil of 7

Coal, cannel 144

Coal sections 143

Colours for injections 178

Condenser, cheap 51

Coniferous wood 144

Corallines 81

Coral sections 143

Cornea, nerves of 169

Covers, glass, to cut 26

Covers, ornamental paper ... 57

Covers, glass, to clean 28

Covers, to gauge 27, 28

Creosote 7

Crystallization Ill

PAOK

Crystallization, compound... 115

Crystals, sections of 157

Cuticles, siliceous 121

D.

DA.MMA.R 44

Dammar and benzole 20

Dammar cement 45

Deane's compound 125

Decalcifying process 141

Diamond beetle 88

DiatomacesB 58, 60

Diatomacese, cleansing of ... 61
Diatomacese, collection of ... 59
Diatoms, cleansing of by Mr.

Eylands 63

Diatoms in situ, to mount by

Ry lands' method .., 1^

Diatoms, to bleach 65

Diatoms, to mount 63, 67, 69

Diatoms, to mount in Canada

balsam 97

Difi^urentiation, chemical ... 5
Differentiation, mechanical 5, 7

Digester, Papin's 15

Disc revolver. Beck's 63

Dissection 160

Drying 11

Drying tissues, Mr. Suffolk's

• process 159

Dyticus, foot of 109

Dyticus, spiracles of 109

Dyticus, wings of 109

E.

Earth, Bermtida 72

Echini, spines of 142

Eggs of insects, to preserve 137

Equiseta, spores of 202

Equisetum, cuticle of 120

Electricity 21

Elutriation 66

Entomostraca 134

fASBAHTS, Mr., hia medium 134

IWthBM of birds 110

Pert of insooU 108

IPernt, fhiotiQiHtiini of 201

Ttma, aeBlesof. 61

FoniB, wares oE S5

Rbrin IB

File or Rubber, comadum 140

rilter, faibe 77

Biniriiinfr 68

Fish, sealBB of 88

FihIi, tails and Bus of --.,-. ^- 84

Flint, Bootiona of 146

Flustrn UTiculapie 119

Foraminifera , 73

Forarairifen, Bofitions of ... 78
Foraminifera, to cleanse... 74, 7o

Forceps 37

, Fn?:{^}a, bulldog ITS

i, ForcepB, oomprBi ' "" ""

Foroeps, Ooode'e

Fwuops, Page's oa

F««ep9, Spi^ncer'a 41

Foroeps, noodoii 38

FtoBHing tisauBs 11

Froe, ooraea of 8

Froit-stones, seetioDBof. 150

Fuohalno 8

Fungi and moulds 87

G.

Gelatibe 17, 177

Qaraninm, petsl of 80

Gillsotfish IBS

Oiizards 173

Olasa-eDgraTiiig 19

Glno 177

OlnSjliquid 46

Ohie, Touiive 45

. Glycerine... 6, 7, 10, 13, 124, 137

Glyoerine and gum IS

Dlyoerii,B jelly V.

. GlycBrine, refractiTO pnwei

GlTOBrine,'iiwof|byMeaam!

SnffoUc and Hifllop 1!

Goadbj, Mr. V

Goadby's fluid i;

Gosdby's solution II

Gold, ohloride of 8, 1!

Gold, chloride of, and po-

tassium

3uano, diatoms in

Guano, diatoms in, by Mr.

Eoberts '

Guano, spurious

Gum

Gum-waier ■

Gum-water, eitra adliebiTe

Hj;HiTOXILIHE ,.

HyperosDiic acid ...

Injeotion, blue, transparent 11

otion, process of 1.

ctions I

ctioQs by double deoom-

212

raDEX.

VAOB

Injections, to mount 184

Injections, transparent 186

Injections, twofold 184

Injections, various 189

Insects, bleaching of 21

Insects, examination of, by

polarized light 21

Insects, eyes of 10, 89

Insects, internal organs of... 17

Insects, legs and feet of 88

Insects, muscles of 21

Insects, scales of 81

Insects, to moimt in balsam 104

Insects, trachese of 92

Inversion of objects 60

Iodine 6

J.

jAPANblack 46

K.

KBRA.TIN 17

Kesteven on brain and spinal

cord 12

Kidney, injected 166

Knives, dissecting 37, 161

L.

Labelling on glass 19

Labels 49

Laminae, thin 15

Lamp, Bunsen's 42

Lamp, spirit 42

Larv88, skins of 84

Lathe for sections, Butter-
worth's 144

Leaves, cuticle of 79

Leaves, hairy 79, 86

Leaves, parenchyma of 17

Leaves, sections of 154

Lenses, immersion 23

Lieberkuhn 89

Light, polarized 20

PAOB

Lime-water 6

Liver, injected ...., 166

Lung, injected 166

M.

Maceration 13, 16, 162

Mayflies 138

Mercury bichloride 9, 11

Mercury nitrate 17

Metal capsules for Canada

balsam 94

Microscope, dissecting 160

Microscope, Gairdner's 64

Microscope, inverted 22

Mosses and AlgSD «. 133

Mosses, fructification of 85

Mosses, to preserve 125

Mounting, dry 62

Mounting in Canada balsam 90

Mouth of insects 109

Muscle 164

Muscular fibre 15

N.

Nails, softened 15

Needles, curved 176

Needles, dissecting 161

Needles, use of 37

Nerve-tissue 13, 166

Neutral media 2

Neutral tints 20

Nitric acid 80

Nummulites 17

0.

Oatmeal, parched U

Objectives of wide angle ... 4

Objects small, to take up... 36

Oils, essential 19

Oily and fatty matters 19

Oily and fatty matters, sol-
vents of 19

Onion^ raphides of 120

FSmioMid

OfBdin

Ojtten, young

P.

... 8
15,17
.... 117

SEX.

- Saw, watoh-apring

Scales of eel

SoalosoIBah

Scales of plantfi

SuisBorB, dissecting

Sea-maU

213

., 140
.. 117
,. 117

.. lai
r, Ifil

.. 87
.. 75

PaloB) of oeresla

... 121

Palladium, proto-ohloride of S

Seeds

Seeds and pollen

.. 81

.. no

P^^y,.ieroscoplo...m

Saads, BBCtions of.

Sertularidte

Sheila, pearly, seotion of

Sheila, aections of

Silioft, colloid

Silica, or eilicio aoid

Silica, yegatable

SilicaouH matter, solifcnta

.- 158
.. 119
.. 142
-. WO
.. 18
.. 18
.. 67
of 18

Plpotta

Podura, EOBles of

PS'"'::

... 68
of-

... in

po^ .....:

... 100
... 135
... Ifil
,,.,,0

HS-^'.;;;;;;:::::::;;;;:;;

.. 4S

.. 17

, 13, H

PotaealHin, ferto-cjanide

25,94
.. 57

Slides, to cover and on
mant

R.

RATHroKB

Raphides for poloriscope

.... 80
... 120

Bodffl, liquor 5

Soft tissues, seotiuQS of ..

.. 155

Spioer, the Rev. W. W

praBBrvativa fluid

Spicula of sponges

Spider, poison-glanda of. ,

Spinal cord

Spiraolea

Spleen, injected

Sl>onga, BBctionB of

Stage of microscope, hot
StBjning

.. 127
.. 103
,. 168
.- ]fl5
,. 168
,. IKS
.. 166
,. 22
.. 7

ffin(rB,iroa

Knga, Tulcanila

Eings, lino SBd Un

... 130
... 131
... 131
... 131
... 37

Riull, SMtiODS of

s.

3*L1CINB

Saatcmino

... 164

... 113
... 113

-. 1S9

'.'. 60

Stand, Mr. Loj's

Stand, universal

214

INDEX.

rAOK

Starches 119

Star-fish 78

Stomach of molluscs 1 70

Sublimate, corrosive 17

Sug;ar 7

Syringe 175

Syringe for balsam 93

Syringe, glass 162

Syrup 14

T.

Table, brass 42

Tannic acid, or Tannin 6

Tannin 9, 11, 17

Teasing by needles 3

Teeth, sections of 92, 146

Teeth, softened 15

Tendon 17

Testae 18

Thwaite's liquid 126

Ti n tubes, collapsible 44

Tongues of molluscs 169

Tongues or palates of mol-

lusca 118

Tracheae of insects 109, 167

Trough, dissecting 162

Tubes, dipping 37

Turntable, Mr. Hislop's 33

Turntable, Dr. Matthews'... 34
Turntable, Mr. Shadbolt's... 33

PAOB

Turpentine 7, 19

Turpentine, spurious 91

V.

Valentin's knife 155, 184

Varnish, black 48

Varnish, caoutchouc 48

Varnish, sealing-wax 48

Vegetable tissues, dissection
of 162

W.

Watch-qlassbs 41

Waterrbath 22

Wine-glasses, brc^en 42

WhcJebone 14

Whalebone, sections of 151

Wood, fossil 144

Wood, sections of 15ii

Z.

ZiNO, chloride of 126

Zoophytes 87

Zoophytes, to mount 103

Zoophytes, to preserve, by
Dr. Bird's method 101

ROBERT HAROWICKB, PRINTKR, 192, PICCADILLT.

SHELLS AND MOLLUSKS.

ELEMENTS OF CONCHOLOGY ;
An Introduction lo the Natural Histoir "f Shells, and of the Animals
which form them. By Lovell Reeve, F.L.S. Royal Sva, 2 vols. 6a
I Colored Flates. S^S.

CONCHOLOGIA ICONICA; 1

Or. Figures and Descriptions of Iht Shells of MoUusks with remnrfc»(
I on their Affinities. Synonymy, and Geographical Disirihution. By LovEU.
I Resvb, F.L.S. Demy 4to, in double Parts, with ]5 Colored Plates, $10,
■ A detailed list of Monographs and Volumes published may be had.

MISCELLANEOUS.

DESMIUS. FUNGI, LICHENS. MOSSES, &c.
fa, Instructions for iheir Treparation ancl the Formation of an Herbarium
--'-■-' md Edited by the Rev. W. W. Spicer, M.A. \Vith :i4 Illa»
imo, cloth, price $1.50.

■ MANUAL OF BOTANIC TERMS.

r M. C. Cooke. New Edition. Greatly enlarged, and including
it Teratologital terms. With more than 300 II lustrations. i6mo.,
lelolh, price $1.50.

-'HE PREPARATION AND MOUNTING OF MICROSCOPIC!
OBJECTS. I

HOMAS Davies. i6rno, doth, $1.25. ,

tbor'B Esperianfe snd itml. or many of liig friends in overydepirt-
_.. .IcManlpnIalion; and ns It Is Inlcnaod to assist the IwffluDBr as

|a advanced stadcni, the rery rudiments of thn ar

9ete Catalogues of works in the above departments

G. P. PUTNAM'S SONS,

4th Ave. and g3d 8t., Xew I'ork^

]

TO STUDENTS OF NATURAL HISTORY— OLD AND 10tJN(

A NEW NATURAL HISTORY PERIODICAL.

-^

SCIENCE-GOSSIP,

'n Illustrated Medium of Iiiletchange and Gossip fer Sludenti-
and Lovers of Nature-
Edited bv J. E. TAYLOR, F. G. S.,
Author of "Geological Essays," "Geological Stories," etc.

1

ANIMALS, AQUARIA, BEES, BEETLES, BIRDS. BUTTERFLn
FERNS, FISH, FOSSILS. LICHENS, MICROSCOPES. MOSSES.
REPTILES, ROCKS, SEAWEEDS, WILD FLOWERS. Etc. Etc.
It will be published monthly at the price of 2D cents a numberi $3,Z5
a jear. Of the American issue the first five numbers for 1873 are now ready.
Subscriptions can commence in Januaty ot July. Specimen numbers sent
on receipt of 15 cents.

The volume for 1S72, in a handsome American dress, forming a com-
plete and attractive volume on Natural Science and History, copiously Illus-
trated, is also ready for delivery. Price, prepaid by mall, $3.50.
The six volumes prior 10 1871, can also be obtained.

Price, bound in cloth, each ..... $2.50.
Or six volumes bound in two, in half morocco, . iD.oo.
This Magazine has achieved in England a great success, and the pub-
lishers are assured that its republication in this country will be welcomed
by thousands of readers, students and lovers of nature.

The anieles are prepared by able scientists, and while put into popular
language, are guaranteed as being exact and thorough. The illu.stralioiis aie
copious, carefiUly drawn and handsomely printed, while ihe moderate price
places the work within the reach of all.

We give below some few of the English opinions of the magazine.
OPINIONS OF THE PRESS:
"ThiB ]■ ■ very pteBsant Journal that costs bnt s triflo a montli. and fromirbieU

intormailon. It In conducted flod contrihuti^d to by eipert natursliBtP. who are
oheerfulconipanlonB. » all good uaturaliatB are; li^cbnfcal Fnon^b to nishe Ihe gen-
eral reader fael iLat they are In eameft. and am not inaultlue blm by wrliing down to
bin cumprehenslou, hnf naiuni onuoEb and direct enangh in their nconis ot Tacts,
tlieir qusT'Ilnnliig and answering each other caDCecDlng curioaitieB of nature. Tbe
reader wbu bqyp Tor hliDBelt their moutbly DudMt of nntea and ditcnaalona npoa
uleaitanl potntB In natural hlatoiv snd science, Wlil pmbablT And his cuiioHlty BXdIed
and Mb iotereBt In the world about him Ukiiig the (Otm of a tittle Elndyof soma branch

■elf !■ eu dtllehtful and Ihe enthnsiaBm it cicile> eo oenalne and well directed, these
enthnBlanns are conlaglDus, The fault la nnt with liicir but with the public, it tbla
Utile nuu;azlBa be not in favor with a very lar^ circle of reideta,"— ii!r(nnfn«-.

"It 6 a capital IdPa. Scarcely any periodical of the day on gbl to be nmra popu-
lar; and If It answers its deslsi!, It will be more than mont a power to reilne. tu
enlarge, and to elevate tbe mind.'"— A'onawi/oTTBi**.
. "TFb augur great eociees for this much.wanttd montblj. It lj lUnBlraled with
— " It wood enirravtngs."— X>m«'« Bath Jovmai.

— variety of Inrormation It contains on tba most Interesting subjects le reall]'

g."—XiUlemi JotiTval,

It'Donnds with interertln); ln[ormatiDii relative to tbe varied fotmi of animal
'"' — ' In BtiardlaiL

"" ""'""' °"°"' """'"' ' * ' '""" "' '^'ot I'cden

TO STUDENTS OF NATURAL HISTORY— OLD AND lOUNeS

A NEW NATURAL HISTORY PERIODICAL-

. G. P. PUTN-AM's Sons will hereafter publish for tlie Uniied Slat
American edition of the well known English Periodical.

SCIENCE- GOSSIP,

An Illustrated Mtdium of Interchange and Gossip for StudenhM

and Lovers of Nature.

Edited by J. E. TAYLOR, F. G. S.,

Author of " Geological Essays," '■ Geological Stories." etc., etc.

ANIMALS. AQUARIA, BEES. BEETLES. BIRDS, BUTTERFLi;
FERNS, FISH, FOSSILS. LICHENS, MICROSCOPES, MOSSES,
REPTILES, ROCKS. SEAWEEDS. WILDFLOWERS, Etc.. Etc
It will be published monthly at the price of 20 cents a number; (a.l
■ year. Of the American issue the first live numbers for 1S73 are now read,.
Subscriptions can commence in January or July. Specimen nuinbers sent
OD receipt of 15 cents.

The volume for 1S72, in a handsome American dress, forming a com<
plete and attractive volume on Natural Science and History, copiously Illus-
trated, is also ready for delivery. Price, prepaid by mail, ja.50.
The six volumes prior to 1073, can also be obtained.

Price, bound in cloth, each - . . . . $2.50.
Or six volumes bound in two, in half morocco, - 10.00.
This Magazine has achieved in England a great success, and the piil>
lishers are assured that its republication in this country will be welcouwj
by thousands of readers, students and lovers of nature.

The articles are prepared by able scientists, and while put into populn
language, are guaranteed is being exact and thorough. The lUastratians w
copious, carefully drawn and handsomely printed, while the moderate piis
places the work within the reach of all.

We give below some few of the English opinions of the magad
OPINIONS OF THE PRESS.-

"Tble <> B very plearant }onma1 Ihst costs bnt a trifle a month, and from lAU
tbe leadur who Is DO uataniliiit ought to be able to pick up a gooiJ deal or pleitB*^
InfonitHlIon, tt In condncted and contrlbnled to by export ustaraliBtr, wbo an
ctaeerrulcompanlonp. aeall BO°d iiaturallau are; teehnfcal enoQeb to Diake the gen-
eral ntader feel ibat they are In earnefl. and are not iaanltioE blm by wrlitng down to
hl« cuiDpreheDBlon, but nainral euuauh and direct taaagbia Itielr recordt Dt brtl.

toij and

.■S^9Ll

loathly 1)nMef of %Dtee and dlacaulons Bpan
, ... js., p,^ji,[i(ind I1I9 cnrloritj eidied

J — , , Bblj

„ _ . ..Idabont him takiHg tbe tOrmofalUtle study of

<ir Dit^BOrt or knowledge that liaB wan bin readlBatatteDtlDn. For when tbe pCudy
telr If lU dellghll'ul aud Ibe enthUBlBBiu It exctteii «a KenulDBaud well directed, tbc
■—'■—■ — contagioua. Tlie fault 1» not with HbbK, but with the public. If U

.. otthe day onghllo 1)6 miirepopB.

uiu 11 II aniwun me aeeiiu. It will be BIDre than mo^l a power to reSue, lu

re, and to elevate tbe miod?'— A'0BO»i/)»mS*(.

\ve an^r great euccess Ibr tliie much-wutited monlhly. It it llluatrated wllb

lent wood enuravlng?."— A'tmf'j BaUi Journal.

The varlBii o( Jn(ono»lion it contains on the moat Intereeting Bobjecte la roallj

„. —kiiktmy Joiemat.

.^/(_»600Ddewith Inlerestlng

d beat of its kiol.

TO STUDENTS OF NiTURAL HISTORY— OLD AND lOUN^
A NEW NATURAL HISTORY PERIODICAL,

. G. P. Putnam's Sons will hereafter publish for ilie United Sta
American edilion of the well known English Periodical,

SCIENCE- GOSSIP,

An Illustrated Medium of Inlerckangt and Gosupfor StudenaM

and Lovers of Nature.

Edited bv J. E. TAYLOR, F. G. S..

Author of "Geological Essays," "GeoloEical Stories," etc., e

ANIMALS, AQUARIA. BEES. BEETLES. BIRDS, BUTTERFLIH_
FERNS. FISH, FOSSILS, LICHENS. MICROSCOPES. MOSSES.
REPTILES. ROCKS. SEAWEEDS, WILDFLOWERS, Etc.. Etc.

It will be published monthly at the price of 3D cents a number; $2.9;
Sfear. Of the American issue the first Gve numbers for lS73 are now ready.

Subscriptions can commence in January or July. Specimen numbers sent
on receipt of 15 cents.

The volume for 1872. in a handsome American dress, forming a cnm-
plelc and attractive volume on Natural Science and History, copiously Illus-
trated, is also ready for delivery. Price, prepaid by mail, $2.50.

The six volumes prior 10 1873, can also be obtained.

Price, bound in cloth, each - . . . . $2.50.

Or six Tolumes bound in two, in hall morocco, - 10.00.

This Magazine has achieved in England a great success, and Ihe pub-
lishers are assured that its republication in this country will be welcomed
by thousands of readers, students and lovers of nature.

The articles are prepared by able scientists, and while put into popular
language, are guaranteed Bs being enact and thorough. The illustrations are
copious, carefully drauii and handsomely printed, while the moderate price
places the work within the reach of all.

We give below some few Of the English opinions of the magazine. J

OPINIONS OF THE PRESS: ' |

"ThlB iB t, verj pleasant Journal that coeti bnl a trifle a month, and from wU* ,
the reader who la no naCnraUBt oneht to be alila to pick Dp a good deHl of pleasaBf

cbearful campaaionB, a«sll good ualurallBU are: tBcbafcal pooueb to make ttie g<D-
eraireBderreel tbattheTarelnfsmoX. lodBreDDllqeuitlnahim by wri'lng down to
bin comprchenHlOD, bnl nainral eouatib and direct Mongh in tbeir reconlH of f&cta,
their que-iliiiliig and aneweriuK each Dtbei eomJEsBtttt.DurloiLtlaa nf natare. Tbc
reader who bujrp for blnueir tbelr monthl; buaM^^itsB Bnd dlHcneBiona npoa
pleasant poliila In natural hietor; and science. wiU ^cobahli And his cariosity eicfied
and hla Inlereat tn the world about blm taking Ibalbimor a little etudj or some branck
or tliU Bort of knowledge that baa wou bji readteat attention. For when lbs rtady II-
BDir I> «u HeUgbtral and Ihe enlhUBlBBm It excltef eo genuine and well directed, tnew
enlbuBlaBm« Rio cobtagjons. Tbe fsnlt Ib not with itseir. hut with the public. It tliU

"Ii S a capital Idea. Scarcely anj periodical of the day ooght to be morepopo-
aud If It ani'werB its deBlirn, It wl^I ba more than moet a power to refine, to

eular», and to eievaia the minAy—KonamformUt.

" The rarlelv of iotonnBtlon I

monthl;. It le illuBtt

wood eocravings."— AVwi'i Bath jovmal.

Tarielyof information It contains on tbe most intereBtlng Bnbjecta ia reailj

"rAoppblleatlOn before n» la cettatalj ono ol vto tVanesl and beat of ite kind,

■"-" '-■-■-J merit Ib the ewj aiif8ip\aE. BVl^i \n ■»i\4t'E V. vtMia of aciantiM

^^SlndoDI&'and lOTera ot nature wUl tUi4 vMs mfteMMfi toiii>i«.\*\n'CMBi,r-