ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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fluid. Liko others, Mr. Rousselet finds that formalin is a preserving 
material which may be made of much use. By itself it does not fix the 
Rotifers at all well, hut it has the very valuable property of preserving 
the animals without the least shrinkage or turgescence, and as perfectly 
transparent as the fixing process leaves them. A very weak solution of 
• 25 per cent, or less of osmic acid should be allowed to act for a very 
short time only. If the animals become coloured a little by the osmic 
acid, the colour can be removed by passing them for two or three minutes 
through peroxide of hydrogen. For narcotising, the following mixture 
was found to give better results than 2 per cent, cocain alone : — 2 per 
cent, of cocain, 3 parts; methylated spirit, 1 part; and water, 6 parts. 
Different species vary very much in the length of time they require for 
narcotisation. In killing, it is merely necessary to introduce a drop of 
osmic acid on to the animals under water, and then almost immediately 
transfer them to some fresh water in another block, and then again to 
two or three more lots of distilled water, so as to get out all traces of 
the acid. Finally they should be placed in 2*5 per cent, formalin. 
The author gives some useful hints as to how different species should be 
treated. He thinks that he is justified in saying that this unpreparable 
group, as Mr. Bolles Lee has styled the Rotifers, is now fairly conquered. 
Mr. Rousselet hopes to be able to form in time a complete type collection 
of the known Rotatoria. 
Making and Finishing Wax Cells.* — Mr. M. Pflaum makes wax 
cells by first drawing an asphalt (in benzol) ring wider than the intended 
ring on the slide. With a mixture of wax and paraffin in equal parts, 
a cell of the required depth is drawn, and immediately covered with 
asphalt cement. The slide is finished by fastening the cover-glass 
with shellac dissolved in alcohol. For greater permanence a ring of 
zinc white cement is put over the shellac, and for adornment any colour 
of King’s lacquer. 
Japanese Method for Sticking on Paraffin Sections.! — Herr F. 
Reinke highly recommends a method adopted in Japan for making 
paraffin sections adhere to slides and glass plates. It is a combination 
of the albumen method of Mayer and the water method of Gulland, and 
consists in putting a very thin layer of albumen-glycerin on the glass 
plate and then dropping on a little distilled water. The section having 
been laid on the top, the excess of water is removed with blotting-paper, 
and then the preparation is dried at 30°-35°. 
According to Herr v. Erlanger,J this Japanese adhesive method has 
been known for years. This writer saw it used by Cambridge students 
at the Zoological Station at Naples in the winter of 1891-2, and was 
informed that the procedure had been in vogue there for some time. 
Mr. A. B. Lee also writes to a similar effect, and mentions that the 
method was published by Duval, and also by Henneguy in 1891. 
Formalin as a Disinfectant^ — MM. van Ermengcm and Sugg ex- 
amined the disinfecting power of formalin on pathogenic bacteria, 
* Trans. Amer. Micr. Soc., xvii. (1896) pp. 371-6, 
f Zeitschr. f. wiss. Mikr., xii. (1895) pp. 21-3. X Tom. cit., pp. 186-7. 
§ Arch, dc Pharmacie, 1891. Sec Centralbl. f. Bakteriol. u. Parasitenk, l ,e Abt., 
xix. (1896) p. 91. 
1896 
T 
