86 The American Naturalist. [ January: 
ding in celloidin, and sectioning with the microtome in the usual way. 
The sections thus obtained are stained in 
ACID HEMATOXYLIN. . 
Hematoxylin, 1 g., dissolved in a small quantity of absolute alco- 
hol, added to acetic acid (two per cent.) 100 g. 
© One to three hours in the stain is generally sufficient. After stain- 
ing, the sections are to be placed in a : 
LITHIUM SOLUTION.? 
Ferricyanide of potassium (one per ee solution) . ro ccm. 
In this solution the sections generally remain from 2-3 hours. 
The time required for decoloration may be reduced by adding more 
ferricyanide of potassium. After decoloring, the sections are to be 
well washed in water, passed through alcohol, and mounted in balsam 
in the usual way. | 
Instead of the above hematoxylin solution, we may use with equal 
success 
Lithium carbon. (saturated solution 100 ccm. 
j 
ACID CARMINE. 
CE eee aa a so ee a a e eee 
Acetic acid (to per cent) > 2. e koeni E e OCC 
The powdered carmine is heated 2—4 hours in the acid, and the 
solution, after cooling, is then filtered. The time for staining is 24 — 
hours. Decoloration is effected in the same manner as before. The 
process, however, is more rapid than with hematoxylin, and hence it 
must be closely watched. 
Henneguy’s Methods with Pelagic Fish-Eggs.‘—The eggs 
_ may be killed in water strongly acidulated with acetic acid. In the 
course of a few minutes the embryo becomes quite distinct, and ue 
eggs are then transferred to chromic acid, one per cent. At the ene 
of three days they are placed in water, and the chorion removed. After 
24 hours in water, they are placed in ninety per cent. alcohol, 
then in absolute alcohol. Such preparations are excellent for surface 
views, but difficult to section on account of the hardness of the yolk. — 
€ isolation of the germ from the yolk may be accomplished in 6"? 
Ways : i . i 
1. The egg is placed in osmic acid, one per cent., for a few est 
utes, until it has acquired a light brown color, then transferred to 7" 
_ler’s fluid, and the chorion cut open with sharp scissors. In this fuid 
$ Dr. J. Schaffer (Anat. Anz., V., 22, November ed Weigett® 
OE aaa » V., 22, 2x, 1890, p. 643) employe 
a ie A Si al fathia lihi SNR UPT Pea nd with perfect success 
: * Journ. d Anat, et de Physiol., 1888, pp. 416-7. 
