CHAP. III. PULMONAEIA ANGUSTIFOLIA. 109 



4, and four other fruits contained each 3 seeds. The 

 12 illegitimately fertilised short-styled flowers yielded 

 7 fruits, including on an average 1 86 seed ; and one 

 of these fruits contained the maximum number of 

 4 seeds. This result is very surprising in contrast 

 with the absolute barrenness of the long-styled flowers 

 when illegitimately fertilised ; and I was thus led to 

 attend carefully to the degree of self-fertility of the 

 short-styled plants. A plant belonging to this form and 

 covered by a net bore 28 flowers besides those which 

 had been artificially fertilised, and of all these only 

 two produced a fruit each including a single seed. This 

 high degree of self-sterility no doubt depended merely 

 on the stigmas not receiving any pollen, or not a suffi- 

 cient quantity. For after carefully covering all the 

 long-styled plants in my garden, several short-styled 

 plants were left exposed to the visits of humble-bees, 

 and their stigmas will thus have received plenty of 

 short-styled pollen ; and now about half the flowers, 

 thus illegitimately fertilised, set fruit. I judge of this 

 proportion partly from estimation and partly from 

 having examined three large branches, which had borne 

 31 flowers, and these produced 16 fruits. Of the fruits 

 produced 233 were collected (many being left un- 

 gathered), and these included on an average 1*82 

 seed. No less than 16 out of the 233 fruits included 

 the highest possible number of seeds, namely 4, and 

 31 included 3 seeds. So we see how highly fertile 

 these short-styled plants were when illegitimately fer- 

 tilised with their own-form pollen by the aid of bees. 



The great difference in the fertility of the long and 

 short-styled flowers, when both are illegitimately fer- 

 tilised, is a unique case, as far as I have observed with 

 heterostyled plants. The long-styled flowers when thus 

 fertilised arc utterly barren, whilst about half of the 



