i868 i88i] UTOPIAN FLORA 375 



gradation and distinction of the forms of Epipactis and of Letter 696 

 Platanthera ? It may be absurd in me to suggest, but I think 

 you would find curious facts and references in Lecoq's x 

 enormous book, in Vaucher's 2 four volumes, in Hildebrand's 

 Geschlechter Vertheilung* and perhaps in Fournier's De la 

 Fecondation. 1 I wish you all success in your gigantic under- 

 taking ; but what a pity you did not think of it ten years 

 aeo, so as to have accumulated references on all sorts of 



o ' 



subjects. Depend upon it, you will have started a new era 

 in the floras of various countries. I can well believe that 

 Mrs. Hooker will be of the greatest possible use to you in 

 lightening your labours and arranging your materials. 



To J. D. Hooker. Letter 697 



Down, Dec. 5th, 1868. 



. . . Now I want to beg for assistance for the new edition 

 of Origin. Nageli 5 justly urges that plants offer many 

 morphological differences, which from being of no service 

 cannot have been selected, and which he accounts for by 

 an innate principle of progressive development. I find old 



1 Geographic Botanique, 9 vols., 1854-58. 



2 Plantes (? Europe, 4 vols., 1841. 



3 Geschlechter- Vertheilung bei den Pflanzen, I vol., Leipzig, 1867. 



4 De la Fecondation dans les Phanerogames, par Eugene Fournier : 

 thesis published in Paris in 1863. The facts noted in Darwin's copy 

 are the explosive stamens of Parietaria, the submerged flowers of 

 Alisma containing air, the manner of fertilisation of Lopezia, etc. 



5 Nageli's " Enstehung uncl Begriff der Naturhistorischen Art." An 

 address delivered at the public session of the Royal Academy of Sciences 

 of Munich, March 28th, 1865 ; published by the Academy. Darwin's 

 copy is the 2nd edition ; it bears signs, in the pencilled notes on the 

 margins, of having been read with interest. Much of it was trans- 

 lated for him by a German lady, whose version lies with the original 

 among his pamphlets. At p. 27 Nageli writes : " It is remarkable that 

 the useful adaptations which Darwin brings forward in the case of 

 animals, and which may be discovered in numbers among plants, are 

 exclusively of a physiological kind, that they always show the formation 

 or transformation of an organ to a special function. I do not know 

 among plants a morphological modification which can be explained 

 on utilitarian principles." Opposite this passage Darwin has written 

 " a very good objection " : but Nageli's sentence seems to us to be of 

 the nature of a truism, for it is clear that any structure whose evolution 

 can be believed to have come about by Natural Selection must have a 

 function, and the case falls into the physiological category. The various 



