ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
259 
must therefore be relatively large in their case, and when all movements 
cease they should be killed with 20 per cent, formalin, as chromic acid 
precipitates cocain in strong solution. An after-treatment with chromic 
acid in. 1/2 per cent, seems to harden better than formalin alone. When 
a colony of Melicertidse is subjected for 15 minutes to a 1/2 per cent, 
cocain solution and then transferred to another watch-glass with pond 
water, the individual Rotifers come out of the tubes and attach them- 
selves to the bottom of the glass in perfect condition for study. 
(3) Cutting-, including- Imbedding- and Microtomes. 
Photoxylin.* * * § — Prof. P. Mitrophanow sings the praises of photoxylin, 
which was introduced into microscopic technique by Krysinski (1887). 
For sectioning purposes it compares well with celloidin in transparency 
and suitable consistence. It is also exceedingly useful in the treatment 
of very minute bodies, which may be imbedded first in photoxylin and 
then in paraffin. It may also be used with great success in preserving 
fine preparations, embryos, and minute animals, in a certain order on 
glass plates, for museum and demonstration purposes. 
Preparing Lipoma Tissue, f — Dr. Vedeler prepares adipose tissue by 
first fixing in 5 per cent, sublimate solution, and then treating the piece 
with ether repeatedly renewed until all the fat has disappeared. The pieces 
(0*5 cm.) were then hardened in alcohol, stained with hasmatoxylin and 
eosin, and imbedded in paraffin. If the fat had not entirely disappeared 
the paraffin would not penetrate. 
Frazer’s Sliding Microtome. J — Mr. A. Frazer describes a sliding 
microtome, which is intended for students and others who may desire an 
instrument less costly than those constructed on the Thoma-Jung or 
Schanze model. Tne sliding parts of the instrument are similar to 
those in the Schanze model, but the part which raises the object is con- 
structed after the Cathcart design. A further simplification consists in 
making the knife-holder of such a shape that it will hold an ordinary 
razor,. 
(4) Staining- and Injecting. 
Methylen-Blue Staining.§ — Prof. M. Lavdowsky has found that the 
following fluids are more or less satisfactory vehicles for the pigment 
in vital methylen-blue staining : — fl) Pure blood-serum. (2) White of 
egg. (8) Ammonium chloride. (4) Ammonio-chloride of iron. The 
two last are only used in from 1/10-1/2 per cent, solutions in water or 
egg-albumen. Blood-serum, a perfectly indifferent physiological fluid, 
should be taken from an animal of the same genus as that to be experi- 
mented on. After the blood has been allowed to stand for about twelve 
hours the serum is decanted off and then filtered into a tall narrow 
vessel. If the amount be scanty, it may be diluted with an equal bulk 
of 0*5 per cent, of common salt solution, or 0*1 per cent, aqueous 
ammonium chloride solution. Directly the methylen-blue is quite dis- 
* Arcli. Zool. Exper., iii. (1895) pp. 617-21. 
t Centralbl. f. Bakteriol. u. Parasitenk., l t# Abt., xix. (1896) p. 274. 
% Proc. Scottish Micr. Soc., 1894-5, p. 211. 
§ Zeitschr. f. wiss. Mikr., xii. (1895) pp. 177-81. 
