134 BREEDING 



is an unqualified afnrmative. A round is crossed 

 with a wrinkled, and the hybrid is a round, indis- 

 tinguishable from the pure parent round. But if 

 we refuse to be content with this impressionist 

 aspect, and set about to find out as much as possible 

 about the true nature of wrinkledness and roundness, 

 both in the pure and in the hybrid rounds, we shall 

 find that the matter is not by any means so simple. 



The starch grains of pure round and wrinkled 

 peas have already been dealt with. Those of the 

 round are elongate and entire, those of the wrinkled 

 are circular and compound, the number of com- 

 ponent pieces varying between 2 and 8, the commonest 

 number being 6. 



The starch grains of the cotyledons of the first 

 hybrid generation are shown in Fig. 30. They 

 constitute about as complete a blend between the 

 two parental types as can be imagined. In the first 

 place the grains are intermediate in shape ; this has 

 been demonstrated by measurements. They are also 

 intermediate in compoundness, in two ways ; in what 

 may be called the distribution of compoundness, some 

 of the hybrid grains being compound and some of them 

 single ; and, secondly, in what may be called the 

 degree of compoundness of those grains which are 

 compound ; the number of component pieces in the 

 hybrid is intermediate between the number in the 

 starch grains of the wrinkled pea and entirety, as we 

 may name the feature presented by the grains of 

 round peas. The number of component pieces in 

 those hybrid grains which are compound varies 



