858 The American Naturalist. [ September, 
Corrosive Sublimate—Saturated solution in fresh or sea-water ; may 
be used either hot or cold. It acts quickly, and preserves admirably 
for histological purposes. It is especially good combined with copper 
sulphate, acetic acid, or chromic acid. Objects hardened in it should 
be subsequently well washed in distilled water and in iodized alcohol 
(the recipe for which is given below), to remove all traces of the 
sublimate, which in alcohol crystallizes out in the tissues of the organ- 
isms and so injures the preparation. 
Bichromate of Potasstum.—5 per cent. solution in distilled water 
hardens gelatinous organisms slowly, without rendering them fragile. 
It gives, however, a precipitate in alcohol, and discolors the speci- 
men. The discoloration, however, may be removed by adding to the 
alcohol a few drops of concentrated sulphuric acid. 
Copper Sulphate.—s5 per cent. or ro per cent. solution in distilled 
water, used either alone or in combination with corrosive sublimate, 
kills larvae and delicate animals without distortion. The objects should 
be subsequently repeatedly washed with water to remove all traces of 
of the salt, otherwise crystals will form when the object is placed in 
alcohol. 
Various combinations of these reagents are especially useful, and 
some of those most serviceable are given here: 
Alcohol and chromic acid. 
70 cent. alcohol . . . ee 
ee chibi acid... C. eas } equal p. 
Alcohol and hydrochloric acid. 
50 per cent. alcohol . . . tx 6x. AE CA, 
Hydrochloric acid, uc dc Los . "a o XE» 
Iodized alcohol. 
45 per cent, or 70 per cent. alcohol . . „ x... 5 , 100 6€. 
dun SION . 1. ei 5 ee Ross. dB CC 
Chrom-acetic acid, No. 1. 
rper cent. chroteic acid 1.2... 2. u ac 
Concentrated wene ad lu du owe ac 
Chrom-acetic acid, No 2. 
Concede ‘acetic acid Pe Vi.) "4. Toe be 
x Pet cont, chromic wid... a ERBE 
Chrom-osmic acid. 
t per Cent. chromic acid. . . . , Uu». 1.,. 7906 
x por cen DEE NUI . 2.2. u ee "OE 
