Neo-Mendelism 89 



EMERSON then crossed strains having red grains and 

 white cob with strains having white grains and red cob. 

 The F! generation showed all red grains and cobs, as 

 would be expected ; but in the F 2 generation three differ- 

 ent types of individuals appeared as follows : i with red 

 grains and white cob; 2 with red grains and red cob; 

 i with white grains and red cob. This result in the F 2 

 generation differs from any that has been cited, and 

 EMERSON explains it as follows. In this case the two 

 determiners are not coupled; in fact they are antago- 

 nistic, so that no true-breeding types are produced 

 having red grains and red cobs. It is as if the two 

 chromosomes carrying the determiners are mutually 

 repulsive, so that they always pass to different poles of 

 the spindle at the reduction division. EMERSON inter- 

 prets the results of these experiments, therefore, as due 

 to the existence of two coupled chromosomes in the 

 first case and two antagonistic chromosomes in the 

 second case. 



But is there not another way of looking at this 

 situation? Granted that there is such a phenomenon 

 as the coupling of chromosomes, the question arises why 

 the second situation may not also be explained by coup- 

 ling, the difference being that in this case the coupling 

 is between different chromosomes. According to this 

 suggestion the two situations would be represented by 

 the diagram given in fig. 23. Such a scheme explains 

 both cases by using the same kind of force, that is, 

 coupling, and does not call for attraction to explain 

 one situation and repulsion to explain the other. 



This last conception, however, raises the question, 

 why should a chromosome which in some strains of corn 



