Composition of Eggs. 39 
. Baer. It is also believed that M. Strauss saw the vitel- 
lin granules, of which we. shall speak in our second paper, 
since he described in his beautiful work on the anatomy of the 
cockchafer, the yolk of eggs of these Coleoptera, as formed of a 
liquid pulp, composed of granules, and showing on the surface of 
the envelop of the egg a layer of globules. There are allu- 
Sions to these granules in the work of Bandrimont and Martin 
Saint-Ange, which was crowned by the Academy of Sciences. 
But these authors did not separate them from the rest of the yolk 
to make them the subject of special study; they pointed them 
out in the midst of the drops of oil which swim in the yellow of 
the eggs of frogs. Other naturalists who have studied the eggs 
of different Annelids, Helminths, Insects, Arachnids, Crustacea, 
Molluscs (either Cephalopods, Gasteropods or Acephalous), speak 
of globules, without distinguishing them from drops of fat, and, 
Which is more important for the subject of this article, without 
marking any vitellin substance. 
_ M. Dumas and Cahours were the first who clearly distinguished 
In the egg of a hen, a particular proximate principle, the yo 
acterised by its physical properties and by its composition as de- 
duced from chemical analysis. Their researches were not pushed 
further, and they were satisfied by calling by the same collective 
name of egg, all the products of the ovary that serve in any ani- 
mal, after its fecundation, for the reproduction of individuals like 
the parent animal which secreted them. . ‘ 
n examining attentively the eggs of numerous oviparous ani- 
mals, anatomists however have observed marked differences, which 
r 
thin vitellin membrane detected with difliculty under the micro- 
Scope taking its place; and as, one of us has observed, many 
r 
the attention of men of science to the investigation of this sub- 
Ject, by proposing to the meetings, questions relating more or less 
definitely to the particular composition of eggs. It has been for- 
tunate to find in many communications addressed to it, a portion 
