ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
457 
tive index of 1*537. Its sp. gr. is 1*18. It mixes in any proportion 
with alcohol, benzol, toluol, xylol, sulphuric ether, chloroform, and 
petroleum ether. It would be a suitable medium for saturating objects 
with paraffin. Fixed and dehydrated tissues are immersed in a mixture 
of methyl salicylate and absolute alcohol. The proportion of the former 
is increased until the pure salicylate is reached. The object is saturated 
when it becomes transparent and sinks to the bottom of the fluid. The 
paraffin is to be added gradually. Methyl salicylate clarifies the tissues 
well, and does not affect anilin dyes. 
Use of Methylen-blue in Anaerobic Cultivation.* — Prof. G. Kabrhel, 
taking advantage of the well-known property of reducing agents to 
decolorise methylen-blue, has devised a method whereby methylen- 
blue is used as an indicator of the presence or absence of oxygen. 
The indicator is, of course, intended as an adjunct in the cultivation 
of anaerobic organisms. The indicator is a test-tube filled with sugar- 
gelatin coloured with alkaline methylen-blue. 
The apparatus used consists of a large bell-jar with a stop-cock at 
the top. The bell-jar is placed on a flat glass plate, and the two are 
joined by a mixture of two parts fat and one part tallow. Inside the 
bell-jar are placed two pans containing pyrogallol, one on top of the 
other, and separated by strips of glass. The pans are surmounted by 
a series of uncovered and inoculated capsules. The indicator, which is 
also placed inside, is not plugged with cotton-wool, and is fixed up with 
some of the fat-tallow mixture. Caustic potash is added to the pyro- 
gallol, and the stop-cock connected with a hydrogen generator. The 
excess hydrogen is allowed to escape through a small hole in the tallow- 
fat junction of the bell-jar and plate. If all conditions have been 
properly fulfilled, the methylen-blue will be regularly and thoroughly 
decolorised in about 36 hours. 
(6) Miscellaneous. 
Apparatus for Preserving Celloidin-Blocks.f — The box constructed 
for Dr. R. Borrmann for preserving a large number of celloidin-blocks 
Fig. 121. 
stuck on wood or cork, is made of galvanised iron, and measures 30 by 
23 by 3*5 cm. The pan (fig. 122) has a wide lip a , b, and is sur- 
mounted by a lid e held on by a clamp i. c' c , d' d are felt pads. 
* Centralbl. Bakt. u. Par., l ta Abt., xxv. (1899) pp. 555-61 (1 fig.), 
f Zeitschr. f. wiss. Mikr., xv. (1899) pp. 433-7 (2 figs.). 
