944 THE THEORIES OF EVOLUTION 



sophie Zoologique" which treats of nervous phenom- 

 ena, feelings, sensibility, psychology, and holds for us 

 a historical interest only. 



His two great laws, however, deducted from obser- 

 vation, or rather foreseen intuitively, are all that has 

 survived from his works and been bequeathed to sci- 

 ence, forming the basis of all the so-called Lamarck- 

 ian theories. 



The truth is that Lamarckism never was a real 

 system. Its main tenets have never been systematised 

 by any theorician nor combined into a definite creed. 

 Lamarckism is far more difficult to define than Dar- 

 winism or Neo-Darwinism. Darwinism emphasises 

 the part played by innate variations, modifications 

 predetermined in the germ and due to chance, and it 

 regards the struggle for life between individuals and 

 between species, and the resultant natural selection, 

 as the main factors of evolution. 



Neo-Darwinism, which has found its most complete 

 expression in Weismann's writings, constitutes a well- 

 harmonised system of conceptions relative to the struc- 

 ture of living matter, ontogenesis, heredity, evolution 

 of species, etc. v Lamarckism on the other hand is not 

 so much a system as a point of view, an attitude to- 

 wards the main biological questions. 



Whatever theory emphasises the influence of the 

 environment and the direct adaptation of individuals 

 to their environment, whatever theory gives to actual 



