ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
407 
Effect of Hardenings Reagents on Nerve-cells."^— Dr. E. Sehrwald 
calculates that the large cells of the central nervous system become 
shrivelled to the extent of 21-26 per cent., owing to the effect of the 
hardening fluids necessary for producing Golgi’s staining. The shrivel- 
ling is accompanied by warping, a result induced by the fibres and pro- 
cesses from the cells being incrusted with metallic salts. From the 
warpings and curves produced in the fibres, the author makes his 
calculation as to the diminution in size of the cells. 
Staining and permanent Preservation of Histological Elements, 
isolated by means of caustic potash or nitric acid.f — Mr. S. H. 
Gage and Mrs. S. P. Gage point out the methods of checking completely 
the action of KHO and HNO^ at will, so that the isolated elements may 
be permanently preserved in alcohol or glycerin, and also stained in the 
usual way. 
30 to 50 per cent, solutions of caustic potash act with great rapidity 
on intercellular substance, and quite slowly on cellular elements, 
while weak solutions rapidly dissolve all the elements. The action of 
the strong solution may be checked at any time by means of a 60 per 
cent, solution of potassium acetate, or by the addition of sufficient 
glacial acetic acid to neutralize the caustic potash and form acetate of 
potash. Either fresh or hardened tissue may be used. The pieces should 
not exceed half a cubic centimetre in size, and fifteen to twenty times as 
much potash solution should be used as tissue. As soon as the elements 
separate readily the caustic potash solution should be poured off and re- 
placed by a copious supply of a 60 per cent, solution of acetate of potash, 
to which one per cent, glacial acetic acid has been added. The isolated 
elements may be mounted in acetate of potash, in glycerin, or in glycerin- 
jelly. If the elements are to be stained, they must be soaked for twenty- 
four hours or more in a saturated aqueous solution of alum. They are 
then stained with hsematoxylin, or alum-carmine. 
Nitric acid is used in 20 per cent, solution, and the time required 
varies with the temperature. At the ordinary temperature, one to three 
days are required. If heat be used, the action may be completed in a 
few minutes. The action of the acid is suspended by immersion in 
water until the acid is quite removed. The fibres are teased out in water 
or in glycerin tinged with picric acid, and then mounted in glycerin- 
jelly. If the nuclei are to be stained, the Koch tubercle stain diluted 
4-5 times answers well. The preparations are then mounted in 
balsam. 
Disintegration of Woody Tissues.^ — Prof. G. L. Goodale recom- 
mends the following method of disintegrating woody tissues for micro- 
scopic observation. The tissue is soaked for a sufficient length of time 
in a ten per cent, solution of potassium bichromate, then quickly freed 
from the excess of the salt, by once rinsing in pure water, and immedi- 
ately acted on by concentrated sulphuric acid. After the acid has acted 
for a short time, the tissue is to be placed in a large quantity of water, 
when it will be found to have undergone more or less complete disinte- 
* Zeitschr. f. Wiss. Mikr., vi. (1889) pp. 461-70. 
t Proc. Amer. Soc. Micr., 1889. pp. 34-45. 
X Amer. Journ. Sci., xxxix. (1890) p. 79. 
