MECHANISM OF THE EGG. 



255 



face of the globe. If this globe had the axis of its 

 revolution thus, in the centre, it would not move 



with the change of the position of the egg. But 

 the axis being below the centre, it must turn 

 round with every change in the position of the 

 egg, whether the globe be heavier or lighter than 

 the surrounding white ; were it heavier, it would 

 revolve so as to bring the embryo to the lower 

 part of the shell — were it lighter, to the upper 

 part of the shell. It is lighter, and the matter 

 stands thus : 



This beautiful apparatus has not been understood ; and in the 

 last publication which touches on the subject, the yolk is sup- 

 posed to be heavier, and to hang upon the chalazae. 



