513 
extending backward from the posterior eud of the 
embryo almost as long as the body of the embryo itself, 
connecting the amniotic sac with the exterior (Diag. IV 
and Fig. 1). Of the function of this remarkable tube, I am unable 
to offer any definite explanation, unless it is to convey nutritious 
matter from the white into the amniotic cavity. 
8. As to the fate of this posterior tube of the amnion. At the 
stage when it is in its highest development (Fig. 1), the axis of the 
tube is the same as that of the embryo i. e. the embryo and the tube 
lie in the same straight line. Soon, however, the tube begins to be- 
come curved, at first slightly, then more and more. After a time, 
the distal */, of the tube becomes bent at right angles to the proxi- 
mal !/,. The distal part becoming more and more irregularly curved, 
finally disappears, although the very distal end with the horse-shoe 
ads 
EEE 
Lobe 
> 
In, 
Allanr. Eur 
EN 
SL _ Ammon ER 
yw aN \ 
\ 
—-——_-— 
ny 1d. - 
Yolk- Membrane 
Hormımy fo ad 
arsal View of a Chmmys Embryo A Clem mys Embér o AB days ol S27. 
4 days old, GK7 Frough Me Serous Envelope. AB, 
shaped outline persists for a considerable time (Fig. 2). The proximal 
fifth remains permanently — at least in Clemmys. As the sero- 
