THE VARIETIES OF FERTILISATION. 325 



from a cross tban 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 Esclisclioltzia, in which the offspring of the plants 

 of Bi'azilian 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. 

 There 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." 



* Gross and Self Fertilisation, p. 121. t L.c, p. 109. 



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