Composition of Eggs. 43 
Of the Eges of the Ray.—The new laid egg of a Ray is cov- 
ered with a shell of a bronzed green, whose tissue is made up of 
short felty (feutrées,) fibres ; its general form is a rectangle, more 
or less elongated and curved on both sides; each angle is pro- 
longed in a crooked tongue (languette). The longer side of this 
rectangle extends into a very fine yellowish membrane, which 
looks like the shell. Carefully taking the egg out of the oviduet, 
the membranes are seen secreted in the interior of the great white 
gland which encloses the origin of the oviduct. The surface of 
each of them distended under water, is more than twice that of 
the shell. 
In opening this egg, there is a good deal of yellow contained 
in a transparent gelatinous mass which represents the white of a 
hen’s egg, although it is entirely different. The yellow is in the 
middle of this mass, in one of the transparent cells of the white, 
for the yolk, as M. Baér has very rightly said, has not a vitellin 
membrane of sufficient strength to be observed under the micro- 
Scope, and still less to separate the yellow from the white, so as 
to isolate it. So that in order to get the yellow matter entirely 
pure, it must be taken in an ovula nearly ready to detach itself 
from the ovary and to enter into the oviduct. We may now re- 
only traces of albumen. When these vesicles are exposed to 
the air for several days, they become empty, as it were, losing 
their gelatinous consistency, and then produce a slightly albumin- 
ous liquid which holds suspended some transparent membranes. 
Alcohol equally destroys the gelatinous mass by stopping the co- 
agulation of the membranes. Evaporating the white of the Ray’s 
€gg in vacuo, it is seen that it contains ouly traces of organic sub- 
Stances. The white of a Ray’s egg, then, proportionably small 
compared with the yellow, is different in all its relations from the 
albumen of birds eggs. , 
The study of the yellow of the Ray’s egg ought to establish 
differences still more remarkable between birds eggs and those of 
Cartilaginous fishes. The yellow of the Ray’s egg, under the 
microscope, shows that it is formed of a rather fluid liquid, hold- 
ug suspended drops of a fatty body of light yellow, and a con- 
siderable quantity of small white transparent grains of a reg- 
ular form. We have examined these grains in the different sorts 
of Ray-fish which abound in our Paris markets. 
Lggs of the Torpedo.—We have examined many torpedos 
from the shores of La Rochelle, through the kindness of Dr. 
