240 
Miscellaneous. 
those of Theriodonts; arid this alliance was confirmed by the study 
of other fragments. Some ot the characters presented by these 
remains seem to suggest affinities with the carnivorous mammalia, 
such as have been already indicated by tho humeri of Theriodonts 
and Carnivores. 
The canine tooth of the new South-African reptile, which the 
author proposes to name Titanosuchus ferox, was six times as long 
as that of the allied form Lycosaurus ; and we have in Titanosuchus 
evidence of a carnivorous reptile of more carnassial type than 
Machairodus and other Felines. The author suggests that Titano¬ 
suchus found its prey in the contemporary Pareiosauri , Oudenodonts, 
and Tapinocephalans of the same locality. 
MISCELLANEOUS. 
Method of Investigating the Embryos of Fishes. 
By M. F. Henneguy. 
The ova of the Salmonidm are generally employed by embryolo¬ 
gists in the study of the development of the osseous fishes. It is 
difficult to examine them in the fresh state, either whole, by trans¬ 
mitted light, on account of the thickness of their envelope, or after 
opening them, in consequence of the small consistency of the germ, 
especially at the commencement of segmentation. Chromic acid, 
the reagent most frequently employed to harden these ova, readily 
alters the young cells, and deforms the embryos by compressing 
them between the unextensible envelope of the ovum and the soli¬ 
dified vitelline mass. For the last two years I have employed, in 
the Laboratory of Comparative Embryogeny of the College de 
France, a process which enables us to extract the germs and embryos 
from the ova of trout and salmon with the greatest facility, and 
without causing them to undergo the least alteration. 
I place the ovum for a few minutes in a 1-per-cent, solution of 
osmic acid until it has acquired a light brown colour—then in a 
small vessel containing Miiller’s liquid; and I open it with a fine 
pair of scissors in the midst of this liquid. The central vitelline 
mass, which is coagulated immediately on contact with water, dis¬ 
solves, on the contrary, in the Muller’s liquid, while the solidified 
germ and cutical layer may be extracted from the ovum and ex¬ 
amined upon a glass plate. 
By treating the germ with a solution of methyle green and then 
with glycerine I have been able to observe in the cells of segmenta¬ 
tion the very delicate phenomena lately indicated by Auerbach, 
Biitschli, Strasburger, Hertwig, &c., and which accompany the 
division of the nucleus—namely the radiate arrangement of the pro¬ 
toplasm at the two poles of the cell, the nuclear plate, the bundles 
of filaments which start from it, and the other succeeding phases. 
This proves that the treatment undergone by the ovum does not 
at all alter the elements of the germ. 
