THE VARIETIES OF FERTILISATION. 325 



from a cross than did the seedlings from the fully self-fertile 

 plants. But my anticipation was quite wrong', for they 

 profited in a less degree : " * — really not at all, for the self- 

 fertilised were superior. " An analogous result followed in 

 the case of Eschsclioltzia, in which the offspring of the plants 

 of Brazilian parentage (which were partially [said to be 

 " absolutely " so, on p. Ill] self-sterile) did not profit more 

 from a cross, than did the plants of the far more self-fertile 

 English stock." * 



Mr. Darwin commenced his experiments by saying, " This 

 plant is remarkable from the crossed seedlings not exceeding 

 in height or vigour the self-fertilised. On the other hand, 

 a cross greatly increases the productiveness of the flowers on 

 the parent-plant, and is sometimes necessary in order that 

 they should produce any seed. Moreover, plants thus de- 

 rived are themselves much more fertile than those raised 

 from self-fertilised flowers ; so that the whole advantage of 

 a cross is confined to the reproductive system." t 



Twelve flowers crossed produced eleven good capsules, 

 containing 17'4 grains of seeds ; eighteen self-fertilised 

 flowers produced twelve good capsules, containing 13'61 

 grains: therefore the ratio of fertility was as 100:71. In 

 the first season the heights were as 100 : 86. Being cut 

 down, the next season, they were reversed, " as the self- 

 fertilised plants in three out of four pots were now taller 

 than and flowered before the crossed plants." 



" In the second generation, eleven pairs were raised and 

 grown in competition in the usual manner. The two lots 

 were nearly equal during their whole growth, or as 100:101. 

 Thei'e was no great difference in the number of flowers and 

 capsules produced by the two lots, when both were left freely 

 exposed to the visits of insects." 



• Cross and Self Fertilisation, p. 121. t i-c, p. 109. 



30 



