SPECIES. 117 



see in the vertebrata ; whilst the entire group has only a nega- 

 tive characteristic, the want of vertebrce, which is sufficient 

 alone to show how unnatural it is. As for the rest, the verte- 

 brate animal, even at the first moment of his embryo life, is 

 absolutely irreducible to any invertebrate type whatsoever, 

 contrary to Lamarck's opinion. A vertebrate is to an inver- 

 tebrate as two first numbers are to one another ; all the verte- 

 brata, on the contrary, are one to another as a simple number 

 raised to different powers ; they can all be brought back to 

 their origin, and both the most complicated and the most ele- 

 vated of the series are only the most simple ones arrived at a 

 state of considerable perfection. 



A still weaker side of Lamarck's theory is certainly the 

 decided influence which he attributes to the actions and habits 

 of organised beings, so as to modify them by their own means. 

 The pedantic caprice of his enemies has always hit on this 

 point. ' ' The habit of exercising an organ," he says, ' ' makes 

 it acquire developments and dimensions which insensibly change 

 it, so that in time it becomes very different. On the contrary, 

 the faulty continual exercise of an organ impoverishes it gra- 

 dually, and ends by destroying it."* But it must not be 

 thought that Lamarck gave an appreciable alteration to the 

 organ, an alteration sufficiently rapid to be noticed by our- 

 selves. If some passages of his works make the reader think 

 so, it is plain that they are only the wanderings of a great 

 mind, always weak on the side of the ideas which he has 

 created, and which he cherishes. Lamarck knew very well that 

 an infinite time is the condition of unlimited variability, f 



Darwin is the direct successor of Lamarck, and, in our 

 opinion, the success of his book both in England and France 

 is an index of the progress which scientific ideas have made, 

 since the days of Cuvier, in the path of liberty and indepen- 

 dence. Darwin, like Lamarck, admits unlimited variety; he 

 thinks that all animals must descend from four or five primitive 

 types, and plants from about an equal number ; he is almost 



* Lamarck, Organisation des Corps Vivants, p. 53. 



f For nature " time lias no limit, and consequently has it always at its 

 disposal." Lamarck, Systcme des Animaux sans Vertebres, p. 13, 1801. 



