^44 FROM THE GREEKS TO DARWE^ 



tion of use of these parts, which finally caused them 

 to totally disappear, although they were originally 

 part of the plan of organization in these animals. 



It is eyident that Lamarck was forced to giye 

 such unnatural illustrations as these, because, 

 shut off as he was from experiment and further 

 obseryation, they were the only ones which came 

 within his range of imagination; with all their 

 absurdities, they present a semblance to the ex- 

 pressions of some modern writers. 



In his theory of heredity, Lamarck postulated 

 the inmiediate inheritance of acquired modifica- 

 tions, which we haye learned today is the crucial 

 fallacy in his whole system. He did not expand 

 Buffon's theories in regard to the physical basis 

 of transmission. He brings out the results which 

 spring from free intercrossing, showing that ac- 

 cording to his theory, in the union of indiyiduals 

 which haye been subjected to different enyiron- 

 ments, the effects of enyironment would be neu- 

 tralized, whereas the crossing of indiyiduals which 

 had been subjected to the same enyironment 

 would hasten and perpetuate the transmission of 

 similar effects. To this principle he refers the 

 fact that accidental changes induced by the habits 

 of men are not perpetuated, since they do not oc- 

 cur in both parents, whereas the formation of dis- 

 tinct races in widely different parts of the world 

 is due to the uniformity of their environment. 



