ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
429 
the spirit and leaves the section smooth and adherent to its underlay. 
A higher temperature always fails to get rid of some little amount of 
moisture owing to the unequal rapidity of the evaporation ; hence the 
author lays it down as an axiom that the lowest possible temperature 
is an indispensable condition for the production of a successful prepara- 
tion. The rest of the procedure is that which is commonly adopted. 
Preparation of Venetian Turpentine.* — Dr. H. Suchannek, while 
recording his estimation of the value of Venice turpentine for micro- 
scopical purposes,! advises that it be dissolved in neutral absolute 
alcohol. About equal volumes of these ingredients are mixed together 
in a tall glass vessel and placed in a porcelain tile oven. It is necessary to 
shake the mixture frequently. In from twelve to twenty-four hours the 
turpentine is dissolved and has deposited its impurities, and in from 
twelve to eighteen hours more it will have acquired the necessary con- 
sistence. 
Vosseler’s Cement and Wax Supports. ! — Dr. J. Vosseler recom- 
mends that paper or cardboard slips should be cemented on the slide by 
means of a cement made of commercial bleached shellac. Thoroughly 
broken up shellac is placed in a glass vessel, and alcohol of 90-96 per 
cent, poured over in quantity just sufficient to cover it. The vessel 
covered over is then placed on a paraffin stove. In a comparatively 
short time a clear brownish -looking mass of a syrupy consistence 
results. It is at once ready for use and, according to its inventor, is a 
very valuable cement. 
The wax supports are made out of a mixture of Venetian turpen- 
tine and white wax. A quantity of wax is melted in a porcelain vessel, 
and thereto is added, stirring continually the while, from half to two- 
thirds its bulk of Venetian turpentine. Addition of turpentine softens, 
addition of wax hardens the mixture ; the desired consistence is easily 
ascertained by letting fall a few drops on a glass plate or into water. 
Although sufficiently plastic or impressionable it adheres very firmly 
to glass, hence the position of the supported cover-glass may be altered 
by slight pressure with a needle on one or all of the supports. 
The medium may be used instead of the compressorium in the ex- 
amination of fresh specimens of living Crustacea, the restless movements 
of which are easily restrained by fixing the cover- glass to the slide. 
(6) Miscellaneous. 
Use of Polarized Light in Observing Vegetable Tissues.§— -M. 
Amann describes the results of a long series of observations made on 
the tissues of Mosses under polarized light, which have led to some 
curious results. The different cell-walls present, under these circum- 
stances, very different appearances, depending largely on their degree of 
cuticularization ; and it is possible in this way to define the characters 
of the cells belonging to the different organs in a moss, and even to a 
certain extent to distinguish between the characters presented by dif- 
ferent families. 
* Zeitschr. f. Wiss. Mikr., vii. (1S91) p. 463. f See this Journal, 1890, p. 258. 
X Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 459-62. 
§ Arch. Sci. Phys. et Nat. xxiv. (1890) pp. 502-8. 
2 G 
1891. 
