SPECIES. 119 



teristic. We have shown, while speaking of hybridity, that a 

 native individual disposition ought always to disappear by the 

 mere fact of its being individual ; it quickly disappears through 

 cross-breeding at the tenth generation, if not at the first, in 

 the midst of a population which does not possess it. We fully 

 admit, like Lamarck, that species are formed from one another 

 by the appearance of organic modifications, more or less de- 

 cided ; but we do not leave anything to chance in this pheno- 

 menon, as Darwin does, and we can only see there the applica- 

 tion of general laws. 



It is not one or two animals, born with some special psycho- 

 logical or anatomical disposition, who are destined to generalise 

 themselves by generation : it will be all the individuals of the 

 same species in a certain radius, who will be born with a 

 scarcely appreciable organic modification, resulting, as far as 

 we can tell, in an action of the medium also nearly inappre- 

 ciable by ourselves, but which long ago will have made itself 

 felt by the parents. The new variety will be propagated quite 

 naturally, since it is general, and can but increase with each 

 generation as long as the modifying cause continues to act. 



Etienne Geoffroy had been the worthy successor of Lamarck, 

 with a larger and more philosophical mind. He never fell into 

 his exaggerations, nor into the restrictive applications of the 

 system, like Darwin. Let us see how Isidore Geoflroy* con- 

 tinues his father's theory : " Species is variable under the in- 

 fluence of the ambient medium; differences, more or less 

 considerable according to the power of the modifying causes, 

 may in time be produced, and the present beings may be the 

 descendants of the former being." This doctrine is our own 

 also. 



As to the idea of limited variety, propounded by Isidore 

 Geofiroy, we can only see in it an unfortunate restriction of his 

 father's theory, one of those errors into which even the most 

 judicious minds are liable to fall. Limited ! Does he mean 

 that there is a point where these variations stop, and conse- 

 quently a point where they have commenced ? Does he mean 



* Histoire Naturelle Generate, vol. ii, p. 421, 1859. 



