i862.] ON PLANTS OF THE SAME SPECIES.' 475 



condition of sexual complexity than that of Primula. For 

 in Lythrum there are not merely two, but three castes, differ- 

 ing structurally and physiologically from each other :] 



C. Darwin to Asa Gray. 



Down, August 9 [1862]. 



MY DEAR GRAY, It is late at night, and I am going to 

 write briefly, and of course to beg a favour. 



The Mitchella very good, but pollen apparently equal- 

 sized. I have just examined Hottonia, grand difference in 

 pollen. Echium vulgare, a humbug, merely a case like Thy- 

 mus. But I am almost stark staring mad over Lythrum ; * 

 if I can prove what I fully believe, it is a grand case of 

 TRIMORPHISM, with three different pollens and three stigmas ; 

 I have castrated and fertilised above ninety flowers, trying all 

 the eighteen distinct crosses which are possible within the 

 limits of this one species ! I cannot explain, but I feel sure 

 you would think it a grand case. I have been writing to 

 Botanists to see if I can possibly get L. hyssopifolia, and it has 

 just flashed on me that you might have Lythrum in North 

 America, and I have looked to your Manual. For the love 

 of heaven have a look at some of your species, and if you 

 can get nte seed, do ; I want much to try species with few 

 stamens, if they are dimorphic ; Nescea verticillata I should 

 expect to be trimorphic. Seed ! Seed ! Seed ! I should rather 

 like seed of Mitchella. But oh, Lythrum ! 



Your utterly mad friend, 



C. DARWIN. 



P.S. There is reason in my madness, for I can see that to 

 those who already believe in change of species, these facts 



from Lecoq, 'Geograph. Bot.,' and ordered it and hoped that it was a good 

 sized pamphlet, and nine thick volumes have arrived ! " 



* On another occasion he wrote (to Dr. Gray) with regard to Lyth- 

 rum : " I must hold hard, otherwise I shall spend my life over dimor- 

 phism.' 



