CHAPTER XXIV 

 THE LAMARCKIAN THEORY 



The Lamarckian conception of evolutionary processes has had 

 a more varied career than any of the other existing theories. It 

 has been treated by most evolutionists as the antithesis of Darwin's 

 theory, and most works on this subject devote themselves in some 

 degree to the support of one view and the denial of the other. 

 Under the common designation, the inheritance of acquired char- 

 acters, the ideas credited primarily to Lamarck have usually 

 suffered in these encounters, and have been dismissed with the 

 conclusion that they are still unproved. Common emphasis upon 

 other theories of descent has resulted in their being much more 

 widely accepted. It is true, nevertheless, that an occasional 

 defender has come to the support of Lamarckian views, and that 

 others have lent their support more or less unwittingly to them in 

 dealing with difficult questions of evolution. Weismann, for 

 example, as pointed out in the last chapter, made use of an out- 

 standing environmental factor in expressing a theory of germinal 

 evolution. At present there is a marked tendency among scientists 

 to feel that Lamarck's views have more to commend them than 

 has been admitted, but they have so far not received so convincing 

 support as Darwin's theory of natural selection and the mutation 

 theory. 



Lamarck's Theory of Evolution. Lamarck was not the first 

 scientist to express Ijelief in the shaping of organisms ])y their 

 environment. He was preceded in this by Buff on and Erasmus 

 Darwin, l)ut like Charles Darwin, he was the first to give the 

 matter adequate presentation to impress it upon the scientific 

 world. That his theory was so largely ignored by his contem- 

 poraries was due to a number of factors, among them the opposition 

 of his influential associate, Cuvier. It is abundant testimony to 

 the importance of his theory that his name and Darwin's are 

 preeminent in the literature of evolutionary theories. 



Lamarck's theory, when first published in 1809, consisted of 

 two laws which have been translated as follows: 



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