REPRESENTATIVE LAMARCKIANS 273 



that very question and he attributes the origin of vari- 

 ations to factors whose influence Darwin does not 

 deny. Darwin's leading theory, the theory of natural 

 selection, does not conflict with any of Lamarck's 

 ideas; none of the modern Lamarckians reject that 

 theory, and all of them ascribe to natural selection a 

 role which is not exclusive but very important. 



Lamarckism and Darwinism are alike in another re- 

 spect. Neither system has succeeded in solving all 

 biological problems. No heredity theory has yet 

 found a complete explanation for the transmission of 

 acquired characters; neither has the physiological 

 process by which an organ increases through its activ- 

 ity ever been elucidated. Spencer, for instance, states 

 that "a considerable waste giving considerable power 

 of assimilation, is more favourable to accumulation of 

 tissue than is quiescence with its comparatively feeble 

 assimilation." 13 Le Dantec on the other hand denies 

 that an}^ waste results from the functioning of organs 

 and asserts that organic activity results in assimila- 

 tion of nutritive reserves. 



Certain objections formulated against the theory 

 of natural selection hold good against Lamarckism. 

 Neither system can account for the appearance of 

 especially complex organs such as the eye of verte- 

 brates, neither do they account for the existence of 



11 Principles of Biology, Vol. I, p. 228. 



