Xll 



HISTORICAL BKETOH. 



M. Isidore Geoffroy Saint-Hilaire, in his lectures dehv- 

 ered in 1850 (of which a Eesume appeared in the " Eevue 

 et Mag. de Zoolog.," Jan., 1851), briefly gives his reason 

 for believing that specific characters " sent fixes, pour 

 chaque esp^ce, tant qu'elle se perpetue au milieu des 

 monies circonstances: ils se modifient, si les circonstances 

 ambiantes viennent a changer." "En resume, Vodserva- 

 tion des animaux sauvages demontre deja la variabilite 

 Umitee des especes. Les experiences sur ^ les animaux 

 sauvages devenus domestiques, et sur les animaux domes- 

 tiques redevenus sauvages, la demontrent plus clairement 

 encore. Ces m^mes experiences prouvent, de plus,^ que les 

 differences produites peuvent etre de valeur generique." 

 In his "Hist. Nat. Generale" (tom. ii, p. 430, 1859) he 

 amplifies analogous conclusions. 



From a circular lately issued it appears that Dr. Freke, 

 in 1851 ('^Dublin Medical Press," p. 332), propounded 

 the doctrine that all ' organic beings have descended from 

 one primordial form. His grounds of belief and treat- 

 ment of the subject are vcholly different from mine ; 

 but as Dr. Freke has now (1861) published his Essay on 

 Jhe "Origin of Species by means of Organic Affinity," 

 the difficult attempt to give any idea of his views would 

 be superfluous on my part. 



Mr. Herbert Spencer, in an Essay (originally pub- 

 Jished in the " Leader," March, 1852, and republished in 

 his " Essays,^' in 1858), has contrasted the theories of the 

 Creation and the Development of organic beings with 

 remarkable skill and force. He argues from the analogy 

 of domestic productions, from the changes which the em- 

 bryos of many species undergo, from the difficulty of dis- 

 tinguishing species and varieties, and from the principle of 

 general gradation, that species liave been modified; and 

 he attributes the modification to the change of circum- 

 ' stances. The author (1855) has also treated Psychology 

 on the principle of the necessary acquirement of each 

 mental power and capacity by gradation. 



In 1852 M. Naudin, a distinguished botanist, expressly 

 stated, in an admirable paper on the Origin of Species 

 ("Eevue Horticole," p. 102; since partly republished in 

 the "Nouvelles Archives du Museum," tom. i, p. 171), his 

 belief that species are formed in an analogous manner as 



