230 The Alligator and Its Allies 



immediate neighborhood of the yolk, seems to 

 consist of a number of very thin concentric layers. 

 It varies in color, in different eggs, from a pale 

 yellowish white, its usual color, to a very decided 

 green. 



As might be expected, no chalazse are present. 



The yolk is a spherical mass, of a pale yellow 

 color, lying in the center of the white. Its di- 

 ameter is so great that it lies very close to the shell 

 around the lesser circumference of the egg, so that 

 it is there covered by only a thin layer of white, 

 and care must be taken in removing the shell from 

 this region in order not to rupture the yolk. The 

 yolk substance is quite fluid and is contained in a 

 rather delicate vitelline membrane. 



The albumen and yolk of the crocodile's egg, 

 as described by Voeltzkow, differ from those of 

 the alligator only in the color of the albumen, 

 which in the crocodile is fiormally light green {^8). 



As pointed out by Clarke, the position of the 

 embryo upon the yolk is subject to some variation. 

 During the earliest stages it may occur at the pole 

 of the yolk nearest the side of the egg ; later it may 

 generally be found toward the end of the egg; 

 and still later it shifts its position to the side of the 

 egg. It is probable, as Clarke says, that the 

 position at the end of the egg secures better pro- 

 tection by the greater amount of white, at that 

 point, between the yolk and the shell; while the 

 later removal to the side of the egg, when the vascu- 



