ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
563 
cultivation by means of a strip of oiled paper laid over tbe cultivation, 
the latter lying on tbe slide. 
Preparations suitable for photographing are made as follows. A 
piece of agar cultivation is imbedded in celloidin and sectioned. The 
sections are then laid for about a minute in 5 per cent, caustic potash 
solution and after having been washed in water are immersed for five 
minutes or more in 5 per cent, acetic acid. The sections are then dried 
and stained for some seconds over the flame in phenol-fuchsin. They 
are again washed with water, and then partially dried with tissue paper. 
The sections are then dehydrated with anilin oil, and the latter having 
been removed with xylol the preparation is mounted in balsam. 
By treating the fuchsin-stained sections for some seconds with a 
1-5 per cent, solution of chromic acid or bichromate of potash, the 
contour of the fungi is said to be brought out more clearly, and the 
original colour to be darkened. 
(3) Cutting-, including Imbedding and Microtomes. 
Notes on Celloidin Technique.* — Mr. A. C. Eyclesheimer writes as 
follows : — “ The high value of celloidin as an imbedding mass is well 
known, f and its superiority over all methods requiring heat is unques- 
tionable, yet, from the fact that its manipulation has been attended by 
many difficulties, it has not come into general use. During the past 
two years I have tried the methods recommended by various authors 
and have found none entirely satisfactory, especially where very long 
series were necessary. The results of my experience are embodied in 
the following method ; the prepared plates or fragments are placed in 
an air-tight chamber ; a 4 oz. salt mouth bottle being very suitable 
for this purpose. Pour into this bottle just enough ether-alcohol (equal 
parts acid, free sulphuric ether, and absolute alcohol) to cover the frag- 
ments. The ether-alcohol should be added until after occasional shaking 
no celloidin remains undissolved; this may take several days. It 
should finally possess the consistency of a very thick oil. The solution 
thus obtained may be labelled No. 4. No. 3 is obtained by taking 
two volumes of No. 4 and diluting with one volume of ether-alcohol. 
No. 2 by proceeding in a like manner with No. 3. No. 1 is a mixture of 
absolute alcohol and sulphuric ether in equal parts. 
The saturation and final imbedding is accomplished thus : the object 
is transferred from 95 per cent, alcohol to solutions 1, 2, 3, 4, succes- 
sively, in each of which it remains from a few hours to days, depending 
upon the size and permeability. For pieces of tissue 2 mm. in diameter 
twenty-four hours in each will generally suffice. For a large brain, 
e. g. that of a cat, a week in each will not be too long. 
In imbedding, unless orientation is desired, the ordinary paper box 
is best. A thin plate of lead is placed in the bottom and the imbedding 
solution poured in. The object is taken from the same solution, and 
with needles wet in ether placed in the desired position. Fine needles 
may be passed through the box to support the object. 
In hardening, the method given by Viallanes of immersing in chloro- 
form is preferable, since the operations may be carried on with much 
* Amer. Nat., xxvi. (1892) pp. 354-7. f See ante , p. 438. 
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