EVOLUTIONAL ZOOLOGY 211 



of species. Lamarck undoubtedly derived much from Buffon, 

 but, unlike his predecessor, he had the courage to adhere to 

 his convictions with unwavering consistency, even in the face 

 of the opposition and ridicule of the great Cuvier. His views 

 in many respects show a close parallel with those of Erasmus 

 Darwin whose Zoonomia had appeared some years before, 

 but there is no certain evidence that he had any knowledge 

 of the evolutionary doctrine of the latter. Lamarck's ear- 

 liest expression of his ideas of descent was in 1801, but the 

 complete elaboration of his theory did not appear until the 

 publication of his "Philosophic Zoologique" in 1809. He taught 

 that first organisms of the simplest structure arose through 

 spontaneous generation, and that from these there have de- 

 veloped in the course of a vast period of time, through gradual 

 change, all of the present species of animals and plants without 

 any break in the continuity. The causes, or the factors, of 

 evolution that have brought about these changes are, accord- 

 ing to Lamarck, the inherited effects of use and disuse, the 

 action of the environment, and the influence of conscious 

 willing and exertion on the part of the animal. Unlike Buffon, 

 who made general application of the principles of the inher- 

 ited effects of the direct action of the environment, Lamarck 

 restricted this factor to the evolution of plants which do not 

 actively use or fail to use their organs, but merely respond 

 by modifications to the influence of environmental changes to 

 which they are subjected. In the transformation of animals, 

 on the other hand, Lamarck agreed with Erasmus Darwin in 

 holding that the environment acts only indirectly upon the 

 individual by presenting new situations to which the animal 

 strives by actual effort to adjust itself through the use or dis- 

 use of its parts. As a fundamental law of organic nature, 

 Lamarck assumed that such modifications, produced in the 

 animal by functional reactions to the environment, are trans- 

 mitted in inheritance. "A bird," for example, Lamarck ar- 

 gued, "driven through want to the water to find its food, will 



