PLANT BREEDING 653 

Fic. 9. RECOMBINATION OF CHARACTERS OF PLANTS SHOWN IN FG. 7, occurring 
in the second hybrid generation. This is a uniform and constant type having the 
short habit of growth and large leaves of the “ Havana’”’ parent, combined with the 
high number of leaves of the “ Cuban” parent. It is now grown in the Connecticut 
River valley and yields 40 per cent. more than the Havana type. 
treme segregation. To take a hypothetical case, suppose two plants are 
crossed in which the flowers of one are twice as long as the flowers of 
the other and that this extra length is controlled by three or four sepa- 
rately heritable factors. If only a few of the egg cells can be fertilized 
on account of dissimilarity from the pollen cells, one would expect only 
those seeds to be formed that would come from the fusion of the germ 
cells nearest alike. Intermediates would therefore be more likely to be 
formed than extremes. There is one other possible way of accounting 
