HISTORICAL SKETCH. xxiii 



remarkable skill and force. He argues from the analogy 

 of domestic productions, from the changes which the 

 embryos of many species undergo, from the difficulty 

 of distinguishing species and varieties, and from the 

 principle of general gradation, that species have been 

 modified; and he attributes the modification to the 

 change of circumstances. The author (1855) has also 

 treated Psychology on the principle of the necessary 

 acquirement of each mental power and capacity by gra- 

 dation. 



In 1853 M. Naudin, a distinguished botanist, ex- 

 pressly stated, in an admirable paper on the Origin of 

 Species ('Eevue Horticole,' p. 102; since partly repub- 

 lished in the ' Nouvelles Archives du Museum,' torn. i. 

 p. 171), his belief that species are formed in an analo- 

 gous manner as varieties are under cultivation; and 

 the latter process he attributes to man's power of selec- 

 tion. But he does not show how selection acts under 

 nature. He believes, like Dean Herbert, that species, 

 when nascent, were more plastic than at present. He 

 lays weight on what he calls the principle of finality, 

 "puissance mysterieuse, indeterminee; fatalite pour les 

 uns; pour les autres, volonte providentielle, dont Tac- 

 tion incessante sur les etres vivants determine, a toutes 

 1^ ^poques de I'existence du monde, la forme, le vol- 

 ume, et la duree de chacun d'eux, en raison de sa des- 

 tines dans I'ordre de choses dont il fait partie. C'est 

 cette puissance qui harmonise chaque membre a I'en- 

 semble, en I'appropriant a la fonction qu'il doit remplir 

 dans I'organisme general de la nature, fonction qui est 

 pour lui sa raison d'etre." * 



• From references in Bronn's ' Untersuohungen Uber die Ent- 

 wickelungs-Gesetze,' it appears tiiat the celebrated botanist and 



