Cuap. II. ABSORPTION OF THE ALBUMEN. 511 
and hard; and, finally, im Testudinina it has a continuous, smooth, wavy surface, 
underlaid by a uniform stratum, as in Trionychidae and Cinosternoide, and sim- 
ilar in structure and hardness with these, but much less in thickness, and only 
equalling one fifth the thickness of the nodules below. 
Sic LON Tin. 
THE ABSORPTION OF ALBUMEN INTO THE YOLK SAC. 
In the last section, we have described the mode of origin and deposition, and 
the structure of the albumen of the Turtle’s egg. In this section, we propose 
to show what becomes of that albumen, and what connection it has with the 
yolk mass, around which it is originally deposited.’ 
The youngest and least advanced egg which we have observed, after the last 
fecundation, was one of Glyptemys insculpta, with an oval shell and a full com- 
plement of albumen, in which segmentation had just begun (Pl 10, fig, 1, 1a). 
In this instance the yolk mass had already lost the globular form which it pos- 
sessed in the ovary, and assumed an oval shape. This oval figure would not, 
at the first glance, intimate that there was any connection between the yolk and 
the albumen which surrounds it; when, however, we observe besides, that not 
only the shape of the yolk mass is changed, but its size also is increased, we 
very naturally infer that this augmentation in bulk is due to the introduction of 
some substance from without mixing with the yolk, and, as the albumen includes 
the yolk, that this is the substance in question. Whether the albumen, in this 
case, was absorbed as soon’as it began to be deposited around the yolk, or not 
till its deposition had gone on for some time or had even been completed, it 
is not possible to say definitely; but imasmuch as in the case of a much older 
egg, (Pl. 9b, fig. 4b,) im which segmentation in the region of the embryonic 
area was already completed and the embryonic disc well defined, (e,) the yolk sac 
was plainly oval, (y,) and larger than when it left the ovary, whilst the albumen 
was as yet only partially deposited in a thin layer, (a) and no shell was present; 
1 Before proceeding to the consideration of this ? This instance shows that the oval shape of the 
subject, the reader may with advantage take a retro- yolk mass is not derived from the impression of the 
spective glance at the earlier stages of growth of the shell acting as a mould upon its contents, since no 
ovarian ege, and to that effect compare the diagram of shell was as yet present; but arises no doubt from 
the ege represented Pl. 9c, fig. 1 with that of fig. 2 the tendencies inherent in the life of the ege and its 
upon the same plate, and also that of PI. 9d, fig. 3. development. 
