150 



THE CHROMOSOMES 



and on the other side hybrid in character and 

 probably came from such half-fertihzed 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. 



