70 LINAGES. [CHAP. 



in general arrangenaent, and is also capable of self- 

 fertilisation. 



The crimson L. grandiflorum, on the contrary, 

 as Mr. Darwin has shown {Jour. Linn. Soc, Feb. 

 1863) presents two forms, which occur in about 

 equal numbers, and differ little in structure, though 

 greatly in function. In the one form, the column 

 formed by the united styles and the short stigmas, 

 is about half the length of the whole pistil in 

 the other or " long-styled " form. The stigmas also 

 of the short-styled form diverge greatly from each 

 other, and pass out between the filaments of the 

 stamens, thus lying within the tube of the corolla, 

 while in the long-styled form the elongated stig- 

 mas stand nearly upright, and alternate with the 

 anthers. 



By a series of careful and elaborate experiments 

 Mr. Darwin has shown that this species is almost 

 entirely sterile with pollen of its own form. He 

 repeatedly placed pollen of long-styled flowers on 

 the stigmas of the same kind, and pollen of short- 

 styled flowers on stigmas of shoit-styled flowers, but 

 without effect ; while if pollen of a long-styled flower 

 is placed on a short-styled stigma, or vice versd, 

 abundance of seed is produced. In short, the pollen 

 of the L. grandiflorum is differentiated, with respect 

 to the stigmas of all the flowers of the same form, to 

 a degree corresponding with that of distinct species 

 of the same genus, or even of species of distinct 

 genera. 



Linum perenne is also dimorphous, and the differ- 

 ence between the two forms is more conspicuous. 



