1862.] ON PLANTS OF THE SAME SPECIES.' 477 



C. Darwin to Asa Gray. 



Down, November 26 [1862]. 



MY DEAR GRAY, The very day after my last letter, yours 

 of November loth, and the review in ' Silliman,' which I 

 feared might have been lost, reached me. We were all very 

 much interested by the political part of your letter; and in 

 some odd way one never feels that information and opinions 

 painted in a newspaper come from a living source ; they seem 

 dead, whereas all that you write is full of life. The reviews 

 interested me profoundly ; you rashly ask for my opinion, 

 and you must consequently endure a long letter. First for 

 Dimorphism ; I do not at present like the term " Dioecio- 

 dimorphism ; " for I think it gives quite a false notion, that 

 the phenomena are connected with a separation of the sexes. 

 Certainly in Primula there is unequal fertility in the two 

 forms, and I suspect this is the case with Linum ; and, there- 

 fore I felt bound in the Primula paper to state that it might 

 be a step towards a dioecious condition ; though I believe 

 there are no dioecious forms in Primulacese or Linaceae. 

 But the three forms in Lythrum convince me that the phe- 

 nomenon is in no way necessarily connected with any ten- 

 dency to separation of sexes. The case seems to me in re- 

 sult or function to be almost identical with what old C. K. 

 Sprengel called " dichogamy," and which is so frequent in 

 truly hermaphrodite groups ; namely, the pollen and stigma 

 of each flower being mature at different periods. If I 

 am . right, it is very advisable not to use the term " dioe- 

 cious," as this at once brings notions of separation of 

 sexes. 



... I was much perplexed by Oliver's remarks in the 

 ' Natural History Review ' on the Primula case, on the lower 

 plants having sexes more often separated than in the high- 

 er plants, so exactly the reverse of what takes place in 

 animals. Hooker in his review of the ' Orchids ' repeats 

 this remark. There seems to be much truth in what you 



