ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
253 
When cold the liquid is filtered through a fine cloth and kept in stop- 
pered bottles. A small piece of camphor to prevent the development of 
micro-organisms may be placed in each bottle. The slides must be 
perfectly clean, and should be boiled in water acidulated with hydro- 
chloric acid, and, having been rinsed in distilled water, are dried with a 
perfectly clean cloth. Upon the slide is brushed over a layer of this 
fixative, excess of which is immaterial, as it is easily removed later on. 
The sections are then arranged on the slide with a fine brush. 
Directly this is finished the slide is gently heated over a Bunsen’s 
burner. The paraffin is to be softened only, and not melted. Any 
unevenness or folds in the sections at once disappear. As the slide 
cools the paraffin sets; and now if there be too. much of the fixative, it 
may be removed by just sloping the slide so as to drain it off. The 
fixative must now be allowed to dry thoroughly, and it is best to leave 
the slides just covered from dust, &c., until the next day. 
The paraffin is then dissolved in warm turpentine or in chloroform, 
and these last removed by means of a little strong spirit. If the pre- 
parations have been stained before imbedding, nothing remains to be 
done but to dehydrate the section in absolute alcohol, clear up in oil of 
cloves, and mount in balsam. If not stained, the slide is placed in the 
staining solution, and when withdrawn goes straight into spirit. 
The advantages of this method are that the fixative is liquid at 
ordinary temperature, the sections are easily arranged, all folds and 
creases are completely removed, and no air-bubbles trouble the mani- 
pulator. As the fixative is an aqueous solution, the cells of vegetable 
preparations swell up in it to their original size. When properly dried, 
the fixative is insoluble in all reagents and alkalies, &c., except water, 
which causes it to swell up and tends to loosen it from the slide. Unless 
the agar-layer be thick, the fixative does not become coloured in the 
staining solutions. 
The preparations may be mounted either in balsam or glycerin. 
(3) Cutting-, including- Imbedding- and Microtomes. 
Florman’s Method of Imbedding in Celloidin."^ — Dr. S. Apathy 
raises several objections to the method of celloidin imbedding advocated 
and practised by Florman. The principles of the two methods are 
diametrically opposite. Florman advises imbedding in glass capsules 
in a thin solution of celloidin, and then solidifies by allowing the slow 
evaporation of the solvents, ether and alcohol. Dr. S. Apathy’s method 
consists in transferring the objects to solutions of celloidin of increasing 
thickness, and in only allov^ing evaporation of the ether-alcohol when the 
thickest solution has been reached. The objections to Florman’s method 
seem chiefly to consist in the possibility of delicate objects being dis- 
torted, owing to the contraction of the celloidin, and also disarranged ; 
in the long time required for imbedding ; and in the fact that the 
undermost layer is usually left behind when the mass is extracted from 
the capsule. 
But it is possible that the two microtomists are in the habit of 
dealing with different materials; the one with delicate objects, the 
* Zeitsohr. f. Wise. Mikr., vi. (1889) pp. 301-3. 
