410 MK, C. DARWm ON THE ILLEGITIMATE OFFSPRING 



plants in the several classes, will have to be estimated higher 

 in the same proportion. Finally, we see that the illegitimate 

 plants in the three first classes are all "more or less sterile, 

 some being absolutely barren, with one alone almost completely 

 fertile ; in the three latter classes, some of the plants are mode- 

 rately sterile, whilst others are fully fertile or possibly fertile in 

 excess, 



Tlie last point which need here be noticed is that, as far as my 

 means of comparison serve, a certain degree of relation exists be- 

 tween the infertility of the illegitimate first unions between the 

 several forms and that of their illegitimate oflFspring. Thus the two 

 illegitimate unions, from which the seedlings in Classes V. & VI- 

 were derived, yielded a fair amount of seed, and only a few of these 

 plants are in any degree sterile. On the other hand, the illegiti- 

 mate unions between plants of the same form always yield very 

 few seeds, and their seedlings are the most sterile. But the rela- 

 tion is not strict ; for the first six or seven plants in the Table were 

 extremely sterile, out of all proportion to the union from which 

 they were derived. There is also a tolerably close parallelism in 

 each class between the degree of sterility and the dwarfed stature 

 of the plants. As previously stated, an illegitimate plant fertilized 

 by pollen from a legitimate plant has its fertility slightly increased. 

 The importance of the several foregoing conclusions will be ap- 

 parent at the close of this paper, when the illegitimate unions 

 between the forms of the same species, and their illegitimate 

 offspring, are compared in functional power with the hybrid unions 

 and the hybrid offspring of distinct species. 



Genus Ox a lis. 



Dr. Hildebrand * has proved that Oxalis rosea is a trimorphic 

 species, like Lythrum Salicaria. He possessed in the living state 

 the long- styled form alone, and from its seeds, necessarily self- 

 fertilized, he raised seedlings which proved all long-styled ; but, 

 unfortunately, he does not state how many plants were raised. 



Genus Primula. 

 Pkimfla sikensis. 

 I raised during February 1862, from some long-styled plants 



* Ueber den Trimorphismiis in der Gattung Oxalis: Monatsberichte der 

 Akad. der Wissen. zu Berlin, 21st June 1866, p. 373. Also published sepa- 



4 



rately. 



