42 HETEBOSTYLBD DIMOEPHIC PLANTS. Chap. 1. 



from a distinct plant of the same form. In the latter 

 case all the flowers produced capsules, whilst only 67 

 out of 100 of those fertilised with their own pollen pro- 

 duced capsules. The self-fertilised capsules also con- 

 tained seeds, as compared with capsules from flowers 

 fertilised with pollen from a distinct plant of the same 

 form, in the ratio of 72 to 100. 



In order to ascertain how far the present species was 

 spontaneously self-fertile, five long-styled plants were 

 protected by me from insects ; and they bore up to a 

 given period 147 flowers which set 62 capsules ; but 

 many of these soon fell off, showing that they had not 

 been properly fertilised. At the same time five short- 

 styled plants were similarly treated, and they bore 116 

 flowers which ultimately produced only seven capsules. 

 On another occasion 13 protected long-styled plants 

 yielded by weight 25*9 grains of spontaneously self- 

 fertilised seeds. At the same time seven protected 

 short-styled plants yielded only half-a-grain weight of 

 seeds. Therefore the long-styled plants yielded nearly 

 24 times as many spontaneously self-fertilised seeds as 

 did the same number of short-styled plants. The chief 

 cause of this great difference' appears to be, that when 

 the corolla of a long-styled plant falls off, the anthers, 

 from being situated near the bottom of the tube, are 

 necessarily dragged over the stigma and leave pollen 

 on it, as I saw when I hastened the fall of nearly 

 withered flowers ; whereas, in the short-styled flowers, 

 the stamens are seated at the mouth of the corolM, 

 and in falling off do not brush over the lowly-seated 

 stigmas. Hildebrand likewise protected some long* 

 styled and short-styled plants, but neither ever yielded 

 a single capsule. He thinks that the difference in our 

 results may be accounted for by his plants having 

 been kept in a room and never having been shaken ; 



