CHAP. VII. TABLE C. 261 



eighth self-fertilised generation were intercrossed one 

 with another, as in the experiment above referred to ; 

 but this was now effected on plants which had been 

 subjected to two additional generations of self-fer- 

 tilisation. Thirdly, the same plants of the eighth self- 

 fertilised generation were crossed with pollen from 

 plants of a fresh stock brought from a distant garden. 

 Numerous plants were raised from these three sets of 

 seeds, and grown in competition with one another 

 The plants derived from a cross between the self-fer- 

 tilised plants exceeded in height by a little the self- 

 fertilised, viz., as 100 to 92; and in fertility in a greater 

 degree, viz., as 100 to 73. I do not know whether 

 this difference in the result, compared with that in the 

 previous case, can be accounted for by the increased 

 deterioration of the self-fertilised plants from two 

 additional generations of self-fertilisation, and the 

 consequent advantage of any cross whatever, although 

 merely between the self-fertilised plants. But however 

 this may be, the effects of crossing the self-fertilised 

 plants of the eighth generation with a fresh stock were 

 extremely striking ; for the seedlings thus raised were 

 to the self-fertilised of the ninth generation as 100 to 

 52 in height, and as 100 to 3 in fertility ! They were 

 also to the intercrossed plants (derived from crossing 

 two of the self-fertilised plants of the eighth generation) 

 in height as 100 to 56, and in fertility as 100 to 4. 

 Better evidence could hardly be desired of the potent 

 influence of a cross with a fresh stock on plants which 

 had been self-fertilised for eight generations, and had 

 been cultivated all the time under nearly uniform 

 conditions, in comparison with plants self-fertilised 

 for nine generations continuously, or then once inter- 

 crossed, namely in the last generation. 



(3.) Brassica oleraeea. Some flowers on cabbage 



