24: HETEROSTYLED DIMORPHIC PLANTS. Chap. L 



The several foregoing facts led me to try the effects 

 of the two kinds of pollen on the stigmas of the 

 two forms. Four essentially different unions are pos- 

 sible ; namely, the fertilisation of the stigma of the long- 

 styled form by its own-form pollen, and by that of 

 the short-styled; and the stigma of the short-styled 

 form by its own-form pollen, and by that of the long- 

 styled. The fertilisation of either form with pollen from 

 the other formi may be conveniently called a legitimate 

 union, from reasons hereafter to be made clear ; and that 

 of either form with its own-form pollen an illegitimate 

 union. I formerly applied the term " heteromorphic " 

 to the legitimate unions, and " homomorphie " to the 

 illegitimate unions; but after discovering the exist- 

 ence of trimorphic plants, in which many more unions 

 are possible, these two terms ceased to be applicable. 

 The illegitimate -union of both forms might have been 

 tried in three ways ; for a flower of either form may be 

 fertilised with pollen from the same flower, or with that 

 from another flower on the same plant, or with that 

 from a distinct plant of the same form. But to make 

 my experiments perfectly fair, and to avoid any evil 

 result from self-fertilisation or too close interbreeding, 

 I have invariably employed pollen from a distinct 

 plant of the same form for the illegitimate unions of 

 all the species; and therefore it may be observed that 

 I have used the term "own-form pollen" in speaking 

 of such unions. The several plants in all my experi- 

 ments were treated in exactly the same manner, and 

 were carefully protected by fine nets from the access of 

 insects, excepting Thrips, which it is impossible to ex-- 

 elude. I performed all the manipulations myself, and 

 weighed the seeds in a chemical balance; but during 

 many subsequent trials I followed the more accurate 

 plan of counting the seeds. Some of the capsules con- 



