Chap. VII. TABLE A. 271 



of self-fertilised plants 809 ; that is altogether 1,605 

 plants. Some of the species were experimented on 

 during several successive generations ; and it should 

 be borne in mind that in such cases the crossed plants 

 in each generation were crossed with pollen from 

 another crossed plant, and the flowers on the self- 

 fertilised plants were almost always fertilised with 

 their own pollen, though sometimes with pollen from 

 other flowers on the same plant. The crossed plants thus 

 became more or less closely inter-related in the later 

 generations ; and both lots were subjected in each ge- 

 neration to almost absolutely the same conditions, and 

 to nearly the same conditions in the successive gene- 

 rations. It would have been a better plan in some re 

 spects if I had always crossed some flowers either on the 

 self-fertilised or intercrossed plants of each generation 

 with pollen from a non-related plant, grown under dif- 

 ferent conditions, as was done with the plants in Table 

 C ; for by this procedure I should have learnt how much 

 the offspring became deteriorated through continued 

 self-fertilisation in the successive generations. As the 

 case stands, the self-fertilised plants of the successive 

 generations in Table A were put into competition with 

 and compared with intercrossed plants, which were 

 probably deteriorated in some degree by being more 

 or less inter-related and grown under similar conditions. 

 Nevertheless, had I always followed the plan in Table 

 C, I should not have discovered the important fact 

 that, although a cross between plants which are rather 

 closely related and which had been subjected to 

 closely similar conditions, gives during several genera- 

 tions some advantage to the offspring, yet that after a 

 time they may be intercrossed with no advantage what- 

 ever to the offspring. Nor should I have learnt that 

 tha self- fertilised plants of the later generations might 



