ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
903 
ordinary photography makes capital slides. In fact, I have some an inch 
square, which I use in this way, mounting it temporarily in a glass slide 
for use on the Microscope. Let all microscopists try it, and they will 
not repent.” 
(6) Miscellaneous. 
Microchemical Reactions of Cork and Cuticle.* — Herr A. Zimmer- 
mann discusses the mode of detection of these substances by the use of 
osmic acid, alkannin, and cyanin. Osmic acid, in a 1 or 2 per cent, 
solution, with warmth, causes a rapid and intense brown or black colour 
of all suberized membranes. When tannins are present, it is recom- 
mended to destroy them by eau-de-Javelle. Lignified are stained much 
more slowly than suberized membranes by osmic acid. A solution of 
alkannin in 50 per cent, alcohol, when warm, causes an intense colour 
in all suberized membranes. It is better to treat first with eau-de- 
Javelle. A very good reagent is obtained by mixing equal volumes of 
glycerin and a concentrated solution of cyanin in 50 per cent, alcohol ; 
after previous treatment with eau-de-Javelle it brings out an intense 
blue staining of lignified and suberized membranes. 
Microscopical Examination of Coal.f — In his researches Herr J. 
Wiesner uses a mixture of a concentrated aqueous solution of potassium 
bichromate and an excess of chromic acid, adding then sufficient water 
to dissolve the separated sulphuric acid. Oxidizable substances are by 
this process coloured a yellowish red which finally passes into green. 
Amorphous carbon will resist this reagent for months ; its opaque 
particles form the chief ingredient of soot, of coal, of anthracite, and of 
black charcoal. Brown coal and brown charcoal are intermediate stages 
between pure carbon and cellulose, and a similar substance is found in 
anthracite. Soot contains, in addition, resinous substances which are 
rapidly dissolved by chromosulphuric acid. Graphite consists of a 
readily oxidizable substance and of small black granules which resist 
the reagent for two months. The black particles found in human lungs 
are identical with soot. 
Microscopical Examination of Textile Fabrics.^ — Herr J. Yinzenz 
publishes a handbook for the microscopical examination of the fabrics of 
commerce, both animal and vegetable. The microscopic characteristics 
of the different fibres are described and delineated, and the microchemical 
reactions are given. 
* Zeitschr. f. Wiss. Mikr., ix. (1892) pp. 58-69. See Bot. Centralbl., lii. (1892) 
p. 84. 
f SB. K. Akad. Wiss. Wien, ci. (1892) pp. 379-418. 
j ‘Anleit. z. Mikrosk. Unters. d. Gespinnstfasern,’ Cottbus, 1890. See Bot. 
Centralbl., lii. (1892) p. 153. 
