LAMARCK'S THEORY OF DESCENT 



349 



order of origin of the invertebrate classes, Lamarck 

 proposes a new genealogical tree. He states that the 

 order of the animal series " is far from simple, that it 

 is branching, and seems even to be composed of 

 several distinct series;" though farther on (p. 456) 

 he adds : 



" Je regarde I'ordre de la production des animaux 

 comme form6 de deux s6ries distinctes. 



" Ainsi, je soumets k la meditation des zoologistes 

 I'ordre pr6sum6 de la formation des animaux, tel 

 que I'exprime le tableau suivant : " 



In the matter of the origin of instinct, as in evolu- 

 tion in general, Lamarck appears to have laid the 

 foundation on which Darwin's views, though he 

 throws aside Lamarck's factors, must rest. The " in- 

 herited habit " theory is thus stated by Lamarck. 



Instinct, he claims, is not common to all animals, 

 since the lowest forms, like plants, are entirely pas- 

 sive under the influences of the surrounding medium ; , 

 they have no wants, are automata. 



" But animals with a nervous system have wants, 

 i.e., they feel hunger, sexual desires, they desire to 

 avoid pain or to seek pleasure, etc. To satisfy these 

 wants they contract habits, which are gradually trans- 

 formed into so many propensities which they can 

 neither resist nor change. Hence arise habitual 

 actions and special propensities, to which we give the 

 name of instinct. 



"These propensities are inherited and become in- 

 nate in the young, so that they act instinctively 

 from the moment of birth. Thus the same habits 

 and instincts are perpetuated from one generation to 

 another, with no notable variations, so long as the 



