ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
419 
staining may be hastened in this case, as in all others where it is desirable, 
by heating the staining agent.* 
Apparatus for making Esmarch’s Rolls.} — The apparatus devised 
by Herr N. Prausnitz for preparing Esmarch’s rolls consists of a tin 
box 10 cm. high, 23 cm. broad, and 19 cm. deep. In the middle of the 
short sides two grooves are cut out for the insertion of a spindle worked 
by a handle. On the spindle and at a distance of 14 cm. from one 
another are two circular tin plates, in the periphery of which ten round 
holes are cut out. When required for use, the box is filled with water 
heated to 10°-12°, and in the holes are placed test-tubes, filled with 
liquid gelatin. The handle is then turned until the gelatin is set. 
The best results are obtained when the tubes are one-fourth full of 
gelatin. 
New Cultivation Vessel.} — Dr. L. Kamen gives an account of how he 
devised a cultivation vessel suitable for the examination of water, &c., 
and how in its main features it resembles closely that invented by 
Petruschky.§ The main differences seem to be, from the illustrations 
given, that the author’s vessel is 4 cm. longer and 1 cm. broader, and 
that the neck is indented at one side only. 
A comparison of the two sets of drawings will be quite sufficient for 
easily understanding the trivial differences between the two forms. 
Dixon, S. G. — An Apparatus for the Collection of Dust and Fungi for microscopical 
and biological tests. Therapeut. Gaz ., 1890, p. 308. 
(2) Preparing Objects. 
Demonstrating the Membrane of the Red Corpuscle of Batrachia.il 
— Dr. L. Auerbach, after submitting the red corpuscles of Batrachia to 
a renewed investigation, comes to the conclusion that they are invested 
with a colourless membrane. This is demonstrable if a drop of blood, 
carefully protected from loss of fluid, be left alone for some hours. By 
this time the contents of the corpuscle have receded from the membrane, 
usually being massed at the poles. On the addition of physiological salt 
solution, the membrane swells up like a bladder. This may be still 
better observed after hardening in saturated picric acid solution, subse- 
quently washed out with water. Such a preparation, stained with eosin 
and anilin-blue, shows the membrane blue and the adjacent layer red. 
Certain reagents cause the corpuscle to swell up to a thin-walled bladder 
which bursts, allowing the contents to escape, and leaving an empty sac 
behind ; such are sublimate in 0 * 1 to 0 * 25 per cent, solution, 1 per cent, 
boracic acid, chloride of sodium, and chromate of ammonia in 2 to 10 per 
cent, solution. In the corpuscle can be distinguished a cortical and 
medullary substance, the latter inclosing the nucleus. This is well 
* If the picric alcohol solution, as given above, is diluted with an equal volume 
of water, it makes a most excellent dissociating medium for almost all the tissues. It 
is especially good for epithelia and for smooth and striated muscle. The striation in 
the striated muscle is exceedingly clear and the longitudinal fibrillation of the 
smooth muscle is easy to demonstrate. 
t Centralbl. f. Bakteriol. u. Parasitenk., ix. (1891) pp. 129-30 (1 fig.). 
t T. c,, pp. 165-7 (2 figs.). § See this Journal, 1*91, p. 131. 
|| Anat. Anz., v. (1890) pp. 570-8 (2 figs.). See Zeitschr. f. Wiss. Mikr., vii. 
(1891) pp. 511-2. 
