193 
71. The egg in its inception is a minute aggregation of fluid 
matter ; but this drop of fluid has not a homogeneous, uniform 
density throughout, but makes its first appearance in the form 
of an indefinitely bounded globule with a greater degree of 
transparency on one side than the other. 
72. Soon, and whilst the egg is yet minute, the albumen 
becomes concentrated and assumes a somewhat globular 
outline. At the same time a condensation takes place at one 
side. 
73. The aim of all these processes becomes now rapidly 
apparent, for soon we find that the albumen has clearly become 
alb. 
a 
61 . 
a , Germinal duct. 
b, Germinal vesicle. 
c, Yolk. 
defined as a separate mass, apart from the yolk, and its super- 
ficies has become condensed into a well-marked envelope, which 
constitutes the germinal vesicle ; whilst the condensation going 
on within it at the last stage has resulted in the formation of 
a clearly-established agglomeration, with a distinct wall around 
it, called the germinal spot. Outside this field of operations, 
and antagonistic to it in character, the yoke has its peculiarities, 
its physiognomy, refraction, density, opacity, and colour, accord- 
ing to the kind of animal into which the egg develops, all tending 
to demonstrate that it is under a different formative influence 
