46 Composition of Eggs. 
and obtuse angles; the largest are four hundredths of a a 
tre, perfectly transparent, but distinetly marked edges. They a 
identical in the yolks in the process of formation, and in the ova- 
rian vesicles, and whatever the size of these ovules from those 
which are only 0™-O1 in diameter, to the largest which are 0™-03. 
In the smaller ovules with diameter varying from U™-001 to 
0°-005, the grains have the same tabular shape (‘en tablettes,”) 
but they were much smaller, and did not exceed two hundredths 
of a millimetre in length. tig these grains are of one di- 
mension in each ovule. But the differences we are about to 
point out, show that the grains sari with the development of 
the ovules, and that the vitellus, when they are little developed, 
has much smaller grains of ichthin than with those which are 
nearer the oviduct or more in the egg. The Ray from which, 
these yolks were taken were hardly 0"-50 long not counting the 
tail, with a weight of 4 or 5 kilogrammes. In our many exam- 
inations of different grains of ichthin, we met occasionally with 
some little tables almost square, others regular or irregular penta- 
e 
ural productions. We tried to crush these graius in an agate 
mortar, and found that generally they break according to the 
axes of the rectangles of these ‘tablettes,’ and not according to 
their diagonals. We studied the grains of yolk developed in 
the largest of our Ray such as in our markets go under the name 
of the soft or white Ray. This is the Raia oxyrhynchus of Lin- 
zeus. We must not forget to remark that individuals of this 
kind of Ray are even two metres long, not counting the tail, that 
sas attain the weight of 100 kilogrammes, and yet the eggs of 
s Ray give the smallest grains of ichthin. Those of the 
pate Ray (Raia fullonica,) and those of “la raie ronce” (Raia 
rubus,) are very much like those of “la raie bordée ;” the most 
noticeable difference consists in their smaller dimensions. ‘The 
largest are only three hundredths of a millimetre. In the eggs of 
these two sorts of Ray, the grains are very sn regular ellipses, 
but the rectangular form is still more common, ” "The vitellin 
grains of the marbled torpedo (Torpedo NE! from La 
Rochelle, are very different in shape from those of the Ray, the 
er being elliptical or cirenlar: there are no rectavgular 
grains; their transparency and their other physical properties are 
hes 1ey are only two hundredths of a millimeter, but 
too, some 2 Variations in she form. Sia tesefal-ps 
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