1808-iS -i | UTOPIAN FLORA 375 



gradation and distinction of the forms of Epipactis and of j.,- t tcr 696 

 Platantheral It maybe absurd in me to t, but I think 



you would find curious facts and references in I ■ 

 enormous book, in Vaucher's 8 four volumes, in Hildebrand's 

 Geschlechter Verthetlung* and perhaps in Fournier's De la 

 Fe*condation. A I wish you .ill success in your gigantic under- 

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



so as to have accumulated references on all sorts ol 

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

 in the floras of various countries. 1 < an well believe th.it 

 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, 1S68. 

 . . . Now 1 want to bc^ for assistance for the new edition 

 of Origin. Nageli 6 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 Giographie Botanique, 9 vols., 1S54-5S. 



' Plantes d'Europe, 4 vols., 1841. 



3 Geschleckter-Vertheilung bei den Pflanzen y 1 vol., Leipzig, r8< 



* l)i la Ficondation dans les PJtan/rogames, par Eugene Fournier: 

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

 are the explosive stamens of Parietaria, the submerged flowers of 

 Alistna containing air, the manner of fertilisation ol . etc. 



5 Nageli's " Enstehung und Begriflf der Naturhistorischen Art." An 

 address delivered at the public session of the Royal A< ademy of Sciences 

 of Munich, March 28th, [865 ; 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 ol 

 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 no: know 

 among plants a morphological modification which can be explained 

 on utilitarian principles." Opposite this pa sage 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 Si :i must have a 



function, and the case falls into the physiological cat< gory. The various 



