480 FOOT. 
aspect. Their shape is either round or slightly flattened (Figs. 
3 and 6). The first is about twice the size of the second, and 
as a rule divides before the second is constricted off, though 
this is not invariable. When the first divides equally the chro- 
matic substance appears equally distributed between the two 
halves; but frequently the first polar body breaks up into 
three or four parts before the second is formed. In these 
Fic. 6. Optical section of entire egg. First polar body divided. Second polar 
body in process of constriction. Vesicular chromosomes. Central aster of spindle. 
Early stage of male pronucleus. 
cases some of the divisions contain no chromatin. Both polar 
bodies break up very soon into several spherical parts ; and by 
the time the pronuclei are formed, there are frequently as 
many as ten spherical bodies of varying sizes distributed with- 
out any regularity, between the egg and its membrane (Fig. 7). 
Wilson (8) has already described this breaking up of the polar 
bodies. 
