ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
899 
of Prof. F. E. Schulze, has devised a method for making these sections. 
The elements of the nervous system of a Cray-fish were stained by 
injecting 1/10 to 1/20 ccm. of a 0*2 per cent, aqueous solution of 
methylen-blue into the ventral blood-sinus ; in about fifteen hours many 
cells and fibres were stained. Preparations thus made retain their 
colour for only about an hour, unless they are treated with reagents 
which precipitate the methylen-blue; the best to use is corrosive subli- 
mate used as a cold, concentrated, aqueous solution. The tissue must 
now be dehydrated in a solution composed of 1 grm. of corrosive 
sublimate and 5 ccm. of methvlal. It is next put in a mixture composed 
of two parts xylol, one part pure methylal, and one part of the de- 
hydrating mixture of sublimate and methylal. After a short time in 
this it is placed in a considerable quantity of xylol for four or five days. 
After this it may be either mounted in xylol-balsam and studied as a 
transparent object, or imbedded in paraffin and cut in the usual manner. 
The sections should be fixed to the slide with Schallibaum’s collodion, 
and not with Mayer’s albumen which discharges the colour. Prepara- 
tions or sections made in this way are serviceable for several weeks. 
Staining Sympathetic Nerve-cells.* — Prof. A. Van Gehuchten 
recommends the following method ; the ganglia are to be extracted 
from animals killed with chloroform and put at once into a mixture 
of 5 parts of 1 per cent, osmic acid and 20 parts of 3 per cent, 
bichromate of potash. Leave in the dark for three days; then wash 
rapidly with distilled water and place in a 0 • 73 per cent, solution of 
nitrate of silver. If there is not a slight precipitate add to the silver 
bath a few drops of the osmio-bichromic solution. Leave the piece in 
the silver bath in the dark for at least two days. Again wash rapidly 
with distilled water, and again immerse in the osmio-bichromic solution. 
After three days and another rapid washing replace in the silver bath 
for at least two days. Then imbed in celloidin. 
Technique for Botanical Investigations.f — Herr J. af Klercker 
describes a method of preparing vegetable microtome sections without 
previous fixing or saturating with paraffin. The object is placed at once 
in solidifying paraffin, and cut with the knife placed very obliquely 
and moistened with water. For dry herbarium material, articles of com- 
merce, &c., he recommends that, before placing in the paraffin, they 
should first be immersed in cold or boiling water, ammonia, or dilute 
potash-ley ; very brittle objects may be saturated with glycerin -gelatin. 
For making permanent preparations of objects containing tannin, the 
author recommends the following fixing solutions : — (1) Flemming’s 
chrom-osmic acid ; (2) a mixture of 1 part Kleinenberg’s picrin- 
sulphuric acid, and 1 part 5 per cent, solution of potassium bichromate ; 
(3) a mixture of 1 part picrin- sulphuric acid and 1 part concentrated 
solution of cupric sulphate ; the second for not more than one day ; the 
third from one to two days. In thick sections the tannin-cells appear 
brown-red by the first and second, green by the third method. 
Staining Cell-nucleus of Pollen-grains.} — Herr A. Meyer uses for 
this purpose a substance which he calls chloral-carmine, consisting of 
* La Cellule, viii. (1892) p. 87. 
f Verhaudl. Biol. Yer. Stockholm, iv. See Bot. Centralbl., lii. (1892) p. 56. 
X Ber. Deutsch. Bot. Gesell., x. (1892) p. 363. 
