150 THE CHROMOSOMES 
and on the other side hybrid in character and 
probably came from such half-fertilized eggs. It 
will be recalled that Baltzer has shown that when 
the cross is made in this direction both paternal and 
Fig. 40.—1, The chromosomes of the egg lie in the equator of the 
spindle, the chromosomes of the sperm at one side; 2, a later stage show- 
ing all of the paternal chromosomes lying at one side’ passing to one pole; 
3 (to the right), later stage; the conditions are the same; there is also a 
supernumerary sperm in the egg (shown to the left, in another section); 
4, same condition as last; 5, pluteus larva that is purely maternal on one 
side, and hybrid on the other. (After Herbst.) 
maternal chromosomes behave normally at each 
division. The conclusion follows with much plausi- 
bility that the absence of paternal characters on one 
side is due to the absence of paternal chromosomes 
on that side. 
