CHAP. I. PRIMULA SINENSIS. 41 



done by me, he tried, in addition, the effects of the 

 plant's own pellen. He counted the seeds. 



It is remarkable that here all the flowers which 

 were fertilised legitimately, as well as those fertilised 

 illegitimately with pollen from a distinct plant be- 

 longing to the same form, yielded capsules; and from 

 this fact it might be inferred that the two forms were 

 reciprocally much more fertile in his case than in 

 mine. But his illegitimately fertilised capsules from 

 both forms contained fewer seeds relatively to the 

 legitimately fertilised capsules than in my experi- 

 ments; for the ratio in his case is as 42 to 100, 

 instead of, as in mine, as 53 to 100. Fertility is a 

 very variable element with most plants, being deter- 

 mined by the conditions to which they are subjected, of 

 which fact I have observed striking instances with the 

 present species; and this may account for the differ- 

 ence between my results and those of Hildebrand. His 

 plants were kept in a room, and perhaps were grown in 

 too small pots or under some other unfavourable condi- 

 tions, for his capsules in almost every case contained 

 a smaller number of seeds than mine, as may be seen 

 by comparing the right-hand columns in Tables 10 

 and 11. 



The most interesting point in Hildebrand's experi- 

 ments is the difference in the effects of illegitimate 

 fertilisation with a flower's own pollen, and with that 

 from a distinct plant of the same form. In the latter 

 case all the flowers produced capsules, whilst only 67 

 out of 100 of those fertilised with their own pollen 

 produced capsules. The self-fertilised capsules also con- 

 tained seeds, as compared with capsules from flowers 

 fertilised with pollen from a distinct plant of the same 

 form, in the ratio of 72 to 100. 



In order to ascertain how far the present species was 



