318 FEETILITY OF CROSSED Chap. IX. 



The fertility of the crossed plants is represented in 

 the table by 100, and that of the self-fertilised by the 

 other figures. There are five cases in which the fertility 

 of the self-fertilised plants is approximately equal to 

 that of the crossed ; nevertheless, in four of these cases 

 the crossed plants were plainly taller, and in the fifth 

 somewhat taller than the self-fertilised. But I should 

 state that in some of these five cases the fertility of 

 the two lots was not strictly ascertained, as the capsules 

 were not actually counted, from appearing equal in 

 number and from all apparently containing a full com- 

 plement of seeds. In only two instances in the table, 

 viz., with Vandellia and in the third generation of 

 Dianthus, the capsules on the self-fertilised plants 

 contained more seed than those on the crossed plants. 

 With Dianthus the ratio between the number of seeds 

 contained in the self-fertilised and crossed capsules 

 was as 125 to 100 ; both sets of plants were left to 

 fertilise themselves under a net; and it is almost 

 certain that the greater fertility of the self-fertilised 

 plants was here due merely to their having varied 

 and become less strictly dichogamous, so as to mature 

 their anthers and stigmas more nearly at the same 

 time than is proper to the species. Excluding the 

 seven cases now referred to, there remain twenty-six 

 in which the crossed plants were manifestly much 

 more fertile, sometimes to an extraordinary degree, 

 than the self-fertilised with which they grew in com- 

 petition. The most striking instances are those in 

 which plants derived from a cross with a fresh stock 

 arc compared with plants of one of the later self-fer- 

 tilised generations ; yet there are some striking cases, 

 as that of Viola, between the intercrossed plants of the 

 same stock and the self-fertilised, even in the first 

 generation. The results most to be trusted arc those 



