CLASSIFICATION AND ADAPTATION II 



which for many recent generations they have been 

 trying to solve, are the Origin of Species and the 

 Origin of Adaptations. 



Former generations of zoologists have assumed 

 that these problems were the same. Lamarck 

 maintained that the peculiarities of different animals 

 were due to the fact that they had become adapted 

 to modes of life different to those of their ancestors, 

 and to those in which allied forms lived, the change 

 of structure being due to the effect of the conditions 

 of life and of the actions of the organs. He did not 

 specially consider the differences of closely allied 

 species, but the peculiarities of marked types such 

 as the long neck of the giraffe, the antlers of stags, 

 the trunk of the elephant, and so on ; but he con- 

 sidered that the action of external conditions was 

 the true cause of evolution, and assumed that in 

 course of time the effects became hereditary. 



Lamarck's views are expounded chiefly in his 

 Philosophie Zoologique, first published in 1809, and 

 an excellent edition of this work with biographical 

 and critical introduction was published by Charles 

 Martins in 1873. Although his conception of the 

 mode in which structural changes were produced is 

 of little importance to those now engaged in the 

 investigation of the process of evolution, since it 

 was naturally based on the physiological ideas of his 

 time, many of which are now obsolete, for the sake 

 of accuracy it is worth while to cite his principal 

 propositions in his own words : — 



' II sera en effet evident que I'etat ou nous voyons 

 tous les animaux, est d'une part, le produit de la 

 composition croissante de 1' organisation, qui tend 

 k former une gradation reguliere, et de 1' autre part 



