The Development of the Alligator 231 
lar area and the allantois begin to function, secures 
a better aération of the blood of the embryo. 
Around the embryo, during the stages that 
precede the formation of the vascular area, is seen 
an irregular area of a lighter color and a mottled 
appearance. This area is bounded by a distinct, 
narrow, white line, and varies in size from perhaps 
a square centimeter to one third the surface of the 
yolk. 
During the earliest stages of development the 
embryo is very transparent; so that, as there is no 
fixed place upon the yolk at which it may be 
expected to occur, it is often very difficult to find. 
Owing to this transparency, to the extreme delicacy 
of the embryo, and to the character of the white, 
the removal of an early embryo from the egg of 
the alligator is a difficult operation and is accom- 
plished only after some practice. 
THE DEVELOPMENT OF THE EMBRYO 
As the writer has pointed out elsewhere (59), 
the embryo of the alligator is often of considerable 
size when the eggislaid. This makes the obtaining 
of the earliest stages of development a difficult 
matter; so that the writer, as has already been 
said, like S. F. Clarke (17), made three trips to the 
South in quest of the desired material. Voeltzkow 
(78) experienced the same difficulty in his work on 
the crocodile, and made several trips to Africa 
