304 'DIFFERENT FORMS OF FLOWERS [1862. 



of each flower being mature at different periods. If I am right, 

 it is very advisable not to use the term " dioecious," 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 of the separated than in the 

 higher 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 

 say,* and it did not occur to me, about no improbability of 

 specialisation in certain lines in lowly organised beings. I 

 could hardly doubt that the hermaphrodite state is the 

 aboriginal one. But how is it in the conjugation of Con- 

 fervse is not one of the two individuals here in fact male, 

 and the other female? I have been much puzzled by this 

 contrast in sexual arrangements between plants and animals. 

 Can there be anything in the following consideration : By 

 roughest calculation about one-third of the British genera of 

 aquatic plants belong to the Linnean classes of Mono and 

 Dicecia ; whilst of terrestrial plants (the aquatic genera being 

 subtracted) only one-thirteenth of the genera belong to these 

 two classes. Is there any truth in this fact generally ? Can 

 aquatic plants, being confined to a small area or small com- 

 munity of individuals, require more free crossing, and there- 

 fore have separate sexes ? But to return to one point, does 

 not Alph. de Candolle say that aquatic plants taken as a 

 whole are lowly organised, compared with terrestrial ; and 

 may not Oliver's remark on the separation of the sexes in 

 lowly organised plants stand in some relation to their being 

 frequently aquatic ? Or is this all rubbish ? 



.... What a magnificent compliment you end your review 

 with ! You and Hooker seem determined to turn my head 



* " Forms which are low in the scale of rank founded on specialisa- 

 scale as respects morphological tion of structure and function." 

 completeness may be high in the Dr. Gray, in ' Silliman's Journal.' 



