476 ' DIFFERENT FORMS OF FLOWERS [1862. 



will modify to a certain extent the whole view of Hy- 

 bridity,* 



[On the same subject he wrote to Sir Joseph Hooker in 

 August 1862 : — 



" Is Oliver at Kew ? When I am established at Bourne- 

 mouth I am completely mad to examine any fresh flowers of 

 any Lythraceous plant, and I would v/rite and ask him if any 

 are in bloom." 



Again he wrote to the same friend in October : — 



" If you ask Oliver, I think he will tell you I have got a 

 real odd case in Lythrum, it interests me extremely, and 

 seems to me the strangest case of propagation recorded 

 amongst plants or animals, viz. a. necessary triple alliance 

 between three hermaphrodites. I feel sure I can now prove 

 the truth of the case from a multitude of crosses made this 

 summer." 



In an article, ' Dimorphism in the Genitalia of Plants ' 

 ('Silliman's Journal,' 1862, vol. xxxiv. p. 419), Dr. Gray 

 pointed out that the structural difference between the two 

 forms of Primula had already been defined in the ' Flora of 

 N. America,' as dioecio-dimorphism. The use of this term 

 called forth the following remarks from my father. The 

 letter also alludes to a review of the ' Fertilisation of Orchids ' 

 in the same volume of ' Silliman's Journal.'] 



* A letter to Dr. Gray (July, 18C2) bears on this point : " A few days 

 ago I made an observation which has surprised me more than it ought to 

 do— it will have to be repeated several times, but I have scarcely a doubt 

 of its accuracy. I stated in my Primula paper that the long-styled form 

 oi Linuin grandijlorum v^z.?^ utterly sterile with its own pollen; I have 

 lately been putting the pollen of the two forms on the stigma of the same 

 flower ; and it strikes me as truly wonderful, that the stigma distinguishes 

 the pollen ; and is penetrated by the tubes of the one and not by those of 

 the other ; nor are the tubes exserted. Or (which is the same thing) the 

 stigma of the one form acts on and is acted on by pollen, which produces 

 not the least effect on the stigma of the other form. Taking sexual power 

 as the criterion of difference, the two forms of this one species may be said 

 to be generically distinct." 



