CHAP. VII. TABLE C. 263 



manner. The parent-plants, however, of the English 

 stock produced many more seeds when fertilised with 

 pollen from another plant than when self-fertilised ; 

 and in Brazil the parent-plants were absolutely sterile 

 unless they were fertilised with pollen from another 

 plant. Intercrossed seedlings, raised in England from 

 the Brazilian stock, compared with self-fertilised seed- 

 lings of the corresponding second generation, yielded 

 seeds in number as 100 to 89 ; both lots of plants being 

 left freely exposed to the visits of insects. If we now 

 turn to the effects of crossing plants of the Brazilian 

 stock with pollen from the English stock, so that 

 plants which had been long exposed to very different 

 conditions were intercrossed, we find that the off- 

 spring were, as before, inferior in height and weight to 

 the plants of the Brazilian stock after two genera- 

 tions of self-fertilisation, but were superior to them 

 in the most marked manner in the number of seeds 

 produced, namely, as 100 to 40 ; both lots of plants 

 being left freely exposed to the visits of insects. 



In the case of Ipomoea, we have seen that the 

 plants derived from a cross with a fresh stock were 

 superior in height as 100 to 78, and in fertility as 100 

 to 51, to the plants of the old stock, although these 

 had been intercrossed during the last ten generations. 

 With Eschscholtzia we have a nearly parallel case, 

 but only as far as fertility is concerned, for the plants 

 derived from a cross with a fresh stock were superior 

 in fertility in the ratio of 100 to 45 to the Brazilian 

 plants, which had been artificially intercrossed in 

 England for the two last generations, and which must 

 have been naturally intercrossed by insects during all 

 previous generations in Brazil, where otherwise they 

 are quite sterile. 



(6.) Dianthus caryophyllus. Plants self-fertilised 



