348 SELF-FEKTILE VAEIETIES. CHAP. IX 



sometimes with the individuals of the same species. 

 Some allied cases of the appearance of varieties which, 

 when self-fertilised, yield more seed and produce off- 

 spring growing taller than their self-fertilised parents, 

 or than the intercrossed plants of the corresponding 

 generation, will now be considered. 



Firstly, in the third and fourth generations of 

 Mimulus luteus, a tall variety, often alluded to, 

 having large white flowers blotched with crimson, 

 appeared amongst both the intercrossed and self- 

 fertilised plants. It prevailed in all the later self- 

 fertilised generations to the exclusion of every other 

 variety, and transmitted its characters faithfully, but 

 disappeared from the intercrossed plants, owing no 

 doubt to their characters being repeatedly blended by 

 crossing. The self-fertilised plants belonging to this 

 variety were not only taller, but more fertile than the 

 intercrossed plants ; though these latter in the earlier 

 generations were much taller and more fertile than the 

 self-fertilised plants. Thus in the fifth generation the 

 self-fertilised plants were to the intercrossed in height 

 as 126 to 100. In the sixth generation they were 

 likewise much taller and finer plants, but were not 

 actually measured ; they produced capsules compared 

 with those on the intercrossed plants, in number, as 147 

 to 100 ; and the self-fertilised capsules contained a 

 greater number of seeds. In the seventh generation 

 the self-fertilised plants were to the crossed in height 

 as 137 to 100 ; and twenty flowers on these self-fer- 

 tilised plants fertilised with their own pollen yielded 

 nineteen very fine capsules, a degree of self-fertility 

 which I have not seen equalled in any other case. This 

 variety seems to have become specially adapted to profit 

 in every way by self-fertilisation, although this process 

 was so injurious to the parent-plants during the first 



