68> Composition of Eggs. 
abundance of vitellin granules, very small, transparent, varying in 
form, more commonly ronnded, insoluble in water and soluble in 
acetic acid. We repeated this experiment several times before he- 
ing certain of its character. The eggs of the T'ritons show a like 
composition, The exterior white is like that of the Frog’s egg. 
The citron or green vitellus, according to the species, contains fat 
and a considerable number of vitellin granules quite rounded, 
which we have studied in the egg taken in the oviduct near being 
hatched, and in the ovula still enclosed in the ovary. The exam- 
ination of these last has shown us this remarkable fact, that the 
_ vitellin grannies increase with the age of their formation. They 
“are very much smaller in the ovula than in the vitellus of the egg. 
These granules are also insoluble iu water and soluble im acetic 
acid, “The ege becomes hard when cooked in boiling water; it - 
then coutains -albuumen too, as well as that of the frog. We have 
alrea mentioned that MM. Martin- -Saint-Ange and Bandrimont 
inles o of the Frog ; they have even given their figure. 
ve ae also given some accurate observations on 
seggs, Toads and Tritons. (Zeitschrift fir 
: per MM. Siebold and Kdlliker, vol. 
Og ie 
iv, part 2, p. 236; 1852.) 
‘The characteristics which we dese ibe, lead us to the conclu- © 
sion, that the granules eis in thes eeggs are of the nature — 
of ichthin, that is, that they are of a like nature with eof 
the Ray’s and the ae seggs. The simple view of the! grains 
under the lens of a microscope suggested this idea; their chara eo 
teristics confirm the identity, which has brought us to the estab- 
lishment of this curious and important physiological fact, that 
the Batrachians besides undergoing, in consequence of their 
metamorphosis, a primary condition of existence like that of fish, 
y 6S se composition has the greatest affinity to those 
of fis 
‘This similarity holds even in the ovules, for we have already 
remarked that the granules of the ichthin from a Ray are smaller 
in the ovules than in the yolk of the egg of these fish. We 
there show, in fact, a like composition for the white surround- 
ing the vitellus, and the presence of ichthin, that immediate neW 
principle abundant in the egg of cartilaginous fishes. 
. Virchow whom we quote, has likewise observed the 
ules (Dotterplattchen) of the eggs of Ray and of fish (loe. cit-). 
We should mention too, that J. Miller has seen and drawn the 
granules of the smooth Ray and of the smooth Hound-fish 
( Galeus pe) SPS Msc Mem. Acad. de Berlin, tome xxvii, 
page 221, pl. 5, 1842. 
We shall give, in the complete work which will be pablishae 
with plates in the Archives du Museum d'Histoire Naturelle, 4 
predecessors. 
detailed account of the researches 
