80 ANIMAL Mr.UIAMsM. 



those modifications continually, when they are advantageous 

 to the species. This cause is natural selection. 



If the chances of birth have given to certain individuals a 

 plight modification which renders them stronger or more 

 active, as the case may be, but altogether more fitted to main- 

 tain the >>tritaalrft>r r.ristence, these individuals are destined by 

 that VTY circumstance to reproduce their kind. Nut only docs 

 their physical superiority increase their chance of longevity, and 

 give them by that means more time to multiply, but, according 

 to Darwin, the very existence of a physical superiority in an 

 animal causes it to Vie preferred above others, for the purpose 

 of reproduction. Thus the entire species would be improved 

 by successive acquisitions of new qualities every time that an 

 individual happened to be born with better endowments than 

 the other representatives of this species. 



The struggle between the old school and that of development 

 threatens to endure yet a long time, without either side finding 

 a victorious argument to overcome the other. Every one 

 knows the reasons which have been alleged on both sides, and 

 for which, in their turn, geology, archaeology, zoology, and 

 agriculture have been laid under contribution. "When and 

 how will the strife end ? No one can as yet answer this ques- 

 tion. Yet, if one might venture a prediction as to the issue 

 of the combat, founded on the actual attitude of the adverse 

 parties, one might predict the defeat of the old school. Their 

 ranks are, in fact, thinned every day ; they evidently grow 

 discouraged, and seem to avow their inability to furnish proofs 

 of a scientific character, by sheltering themselves under an 

 orthodoxy that has nothing in common with the dispute. 



One objection might perhaps be brought against both 

 systems that of keeping too much to generalities in their 

 discussions, aiid not bringing sufficiently into relief the promi- 

 nent points of the debate. 



Thus, wo must allow that Lamarck is much too vague in 

 hi> explanations, when lie attributes to outward circumstances 

 the changes in the living organism. Uetween a need which 

 is manifested and the appearance of a form of organ which 

 corresponds to that need, there is a hiatus which his theory 

 has not filled. Ho tells us that the animal species which we 



