CHAP. VI. ON HETEROSTYLED PLANTS. 69 



cies when illegitimately fertilised, and between the two 

 forms of the same species when similarly fertilised, har- 

 monises well with the view that the result is an inci- 

 dental one which follows from changes gradually effected 

 in their reproductive systems, in order that the sexual 

 elements of the distinct forms should act perfectly on 

 one another. 



Transmission of the Two Forms by Heterostyled 

 'Plants. The transmission of the two forms by hetero- 

 styled plants, with respect to which many facts were 

 given in the last chapter, may perhaps be found here- 

 after to throw some light on their manner of develop- 

 ment. Hildebrand observed that seedlings from the 

 long-styled form of Primula Sinensis when fertilised 

 with pollen from the same form were mostly long-styled, 

 and many analogous cases have since been observed by 

 me. All the known cases are given in the two follow- 

 ing tables (3G and 37). 



We see in these two tables that the offspring from 

 a form illegitimately fertilised with pollen from 

 another plant of the same form belong, with a few 

 exceptions, to the same form as their parents. For 

 instance, out of 162 seedlings from long-styled plants 

 of Primula veris fertilised during five generations in 

 this manner, 156 were long-styled and only 6 short- 

 styled. Of 69 seedlings from P. vulgaris similarly 

 raised all were long-styled. So it was with 56 seedlings 

 from the long-styled form of the trimorphic Lythrum 

 salicaria, and with numerous seedlings from the long- 

 styled form of Oxalis rosea. The offspring from the 

 short-styled forms of dimorphic plants, and from both 

 the mid-styled and short-styled forms of trimorphic 

 plants, fertilised with their own-form pollen, likewise 

 tend to belong to the same form as their parents, but 



