110 HETEROSTYLED DIMOEPIUC PLANTS. Cuap. III. 



short-styled ones produce capsules, and these include a 

 little above two-thirds of the number of seeds yielded 

 by them when legitimately fertilised. The sterility of 

 the illegitimately fertilised long-styled flowers is prob- 

 ably increased by the deteriorated condition of their 

 pollen ; nevertheless this pollen was highly efficient 

 when applied to the stigmas of the short-styled flowers. 

 With several species of Primula the short-styled 

 flowers are much more sterile than the long-styled, 

 when both are illegitimately fertilised ; and it is a 

 tempting view, as formerly remarked, that this greater 

 sterility of the short-styled flowers is a special adapta- 

 tion to check self-fertilisation, as their stigmas are 

 eminently liable to receive their own pollen. This view 

 is even still more tempting in the case of the long- 

 styled form of Idnum grandijlorum. On the other 

 hand, with Pulmonaria angustifolia, it is evident, from 

 the corolla projecting obliquely upwards, that pollen 

 is much more likely to fall on, or to be carried by 

 insects down to the stigma of the short-styled than of 

 the long-styled flowers; yet the short-styled instead 

 of being more sterile, as a ^otection against self-ferti- 

 lisation, are far more fertile than the long-styled, 

 when both are illegitimately fertilised. 



Pulmonaria azurea, according to Hildebrand, is not 

 heterostyled.* 



From an examination of dried flowers of Amsinckia spectabilis, 

 sent me by Prof. Asa Gray, I formerly thought that this plant, 

 a member of the Boraginese, was heterostyled. The pistil 

 varies to an extraordinary degree in length, being in some 

 specimens twice as long as in others, and the point of insertion 

 of the stamens likewise varies. But on raising many plants 

 from seed, I soon became convinced that the whole case was 

 one of mere variability. The first-formed flowers are apt to 



' Die Geschleohter-Vertheilung bei den Pflanzen,' 1867, p. 37. 



