416 H. H. NEWMAN 



occurs only after a prolonged inhibition. When too long in- 

 hibited the whole organism cannot completely recover, but only 

 the apical structures, whose capacity for recovery has been shown 

 b}' Child to be greater than in basal structures. Thus we find 

 heads differentiated without bodies, or with at best rudimentary 

 bodies, and occasionally isolated eyes and hearts. 



11. These experiments may be taken to indicate that in hetero- 

 genic crosses no harmonious structural differentiation can result, 

 without the neutrahzation or elimination of the disharmonious 

 paternal materials. If the latter function actively, so as to ex- 

 press this functioning in heredity, there can result only retarded 

 and subnormal embryos and larvae, and the vast majority of 

 heterogenic hybrids are of this type. 



