HETEROSTYLISM. 209 



Sliort-styled X homostyled gave 8 seeds per capsule. 

 Short-styled X short-styled „ 14 „ „ „ 



Long-styled X homostyled „ 5 „ „ „ 



Long-styled X long-styled -„ 12 „ ,, „ 



The pollen of the homostyled resembled that of the long- 

 styled in appearance, though the stamens were situated high 

 up as in the usual short-styled form. This seems to corrobo- 

 rate Avhat was said above ; for we have here also a long pistil 

 fairly fertile with undifferentiated pollen. 



Another species of Primula which often bears homo- 

 morphic flowers is P. Sinensis. Mr. Darwin's attention was 

 first directed to it by observing a long-styled plant — de- 

 scended from a self-fertilised long-styled parent — with the 

 stamens low down but with the pistil of the short-styled 

 form, though the length of the stylo varied in different 

 flowers on the same umbel. He fertilised eight flowers with 

 their own pollen, obtaining five capsules with an average of 

 forty-three seeds. The examination of the pollen of two 

 equal-styled plants showed a vast number of small shrivelled 

 grains. In the case of two white-flowered plants, in which the 

 pistil was neither properly long-styled nor short-styled, the 

 size of the grains was in the proportion of 100 to 88 ; whereas, 

 between perfectly characterized long and short-styled plants 

 it would have been 100 to 57. 



Of the first-mentioned homomorphic plants, four spon- 

 taneously yielded 180 capsules, with an average of 548 

 seeds, one containing 72 ; a result higher than could be 

 expected of either form if self-fertilised. The next genera- 

 tion proved to he all equal-styled, i.e. the grandchildren of 

 the four original plants. One of these bore an average of 68 

 seeds per capsule, with a maximum of 82 and a minimum of 

 40. Thirteen capsules, spontaneously self-fertilised, yielded 

 an average of 53"2 seeds, " with the astonishing maximum, in 



