ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
803 
C2) Preparing Objects. 
Demonstrating the Cell-Granula.* — Herr R. Altmann recommends 
as fixative for tissues to be examined for the cell-granula a mixture of 
equal volumes of a 5 per cent, solution of bichromate of potash aud 
2 per cent, solution of osmic acid. After twenty-four hours the pieces, 
which are of course very small, are washed in running water for several 
hours; then alcohol (75, 90, 100 per cent.); paraffin imbedding, for 
which they are placed, after the spirit, in a mixture of three parts xylol 
and one part alcohol ; then xylol, xylol-paraffin, lastly paraffin, with a 
melting-point of 58°-60°. The sections made with the “ Support-Mikro- 
tom ” are from one to two p, thick, and are stuck on the slide with a thin 
layer of caoutchouc (caoutchouc dissolved in 25 vols. chloroform). This 
solution is poured on the slide, drained, and after evaporation of chloro- 
form heated gently, the paraffin sections are then stuck on and brushed 
over with a mixture of gun-cotton in aceton and alcohol (2 grm. gun- 
cotton dissolved in 50 ccm. aceton ; of this 5 ccm. are diluted with 
20 ccm. alcohol). 
Acidfuchsin is recommended for staining and picric acid for differen- 
tiating the granula. The former solution is made by dissolving 20 grm. 
acid fuchsin in 100 ccm. of a cold saturated aqueous solution of anilin ; 
the latter is a mixture of 1 vol. saturated alcoholic solution of picric acid 
and 2 vols. water. The sections are stained by pouring the fuchsin 
solution on the slide and carefully heating ; this done, it is washed and 
treated in a similar way with the picric acid solution ; after which 
alcohol, xylol, and dammar. 
Another fixation method, by which the staining is rendered more 
brilliant, though the sections are thicker and the preparations less 
permanent, is as follows : — A saturated solution of red oxide of mercury 
is made in 30 per cent, nitric acid. Immediately before use one vol. 
of the foregoing is mixed with three vols. water and one vol. 50 per 
cent, formic acid. In this solution the fresh pieces are placed for 
several hours, after which they are transferred to alcohol, and thereupon 
the paraffin procedure. 
A quite novel method, but which for mechanical reasons is as yet 
difficult and imperfect, is introduced by the author. It consists in 
freezing fresh pieces of organs and then drying them in vacuo over 
sulphuric acid at a temperature of less than 20° C. By this means no 
alteration in volume occurs in the pieces, which differ from the recent 
condition merely in the absence of water. The next step is to saturate 
the pieces, still in vacuo, with paraffin. 
Demonstrating the Elastic Fibres in the Skin.-f — Sig. Y. Mibelli 
stains the sections in a solution made as follows: — (1) safranin 0*59, 
warm H 2 0 (80°) 50; (2) safranin 0*59, alcohol (90°) 50. When cold 
these two solutions are mixed. 
After having been immersed in the solution for thirty-six to forty- 
* ‘Die Elementarorganismen und ihre Beziekungeu zu den Zellen,’ Leipzig, 
1890, 145 pp., 2 figs., and 21 pis. Cf. Zeitschr. f. Wiss. Mikr., vii. (1890) pp. 199- 
203. 
t Monitore Zool. Ital., i. pp. 17-22. Cf. Zeitschr. f. Wiss. Mikr., vii. (1890) 
pp. 225-6. 
