Bisexual Crosses 297 



ment, which he has effected with his varieties of 

 peas. I have repeated it with the sugar-corn, 

 which gives far better material for demonstra- 

 tion. It starts from the inference that if dissim- 

 ilarity among the pollen grains is excluded, the 

 diversity of the ovules must at once become 

 manifest and vice versa. In other terms, if a 

 hybrid of the first generation is not allowed to 

 fertilize itself, but is pollinated by one of its 

 parents, the outconie will follow Mendel's prin- 

 ciple. 



In order to see an effect on the spikes, pro- 

 duced in this way, it is of course necessary to 

 fertilize them with the pollen of the variety, 

 and not with that of the specific type. The 

 latter would give partly pure starchy grains 

 and partly hybrid kernels, but these would 

 assume the same type. But if we pollinate the 

 hybrid with pollen of a pure sugar-corn, we 

 may predict the result as follows. 



If the spike of the hybrid contains dormant 

 paternal marks in one-half of its kernels and in 

 the other half material latent qualities, the 

 sugar-corn pollen will combine with one-half of 

 the ovules to give hybrids, and with the other 

 half so as to give pure sugar-grains. Hence 

 we see that it will be possible to count out direct- 

 ly the two groups of ovules on inspecting the 

 ripe and dry spikes. Experience teaches us 



