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ORIGINAL COMMUNICATIONS. 



The Influence of the Nervous System in Organic 



Evolution. 



By E. F. Licorish, M.D. 



The majority of biologists may be at present divided into two schools, 

 Neo-Darwinian and Neo-Lamarckian, and besides these there are others 

 who still profess to be unable to reconcile themselves to the truths of 

 organic evolution as interpreted by either party, and who find a pro- 

 minent representative in the celebrated pathologist Virchow. In 

 addition to the above there are a few who, like the writer, are pure 

 Lamarckians, and who, accepting the data of Lamarck, interpret them 

 by the light of present day knowledge, and look on " natural selection " 

 and " survival of the fittest " as mere " figures of speech," expressive of 

 results which have been brought about by functional and environmental 

 adaptation. Of the two leading schools the more numerous is 

 undoubtedly that of the Neo-Darwinians, who see in natural selection 

 an all-sufficient cause for organic evolution. The members of the 

 other school, that of the Neo-Lamarckians, consider natural selection 

 as merely one of the factors of organic evolution, another being the 

 inheritance of the results of the organism's post-natal experiences. 



Let us look more closely at these theories to see if we cannot find 

 therein such a relationship or analogy as would lead us to believe that 

 a slight modification in the basis of one or the other or both will tend 

 to more harmony than at first sight would appear to be possible. For 

 it must be remembered that both schools are represented by able and 

 gifted men who devote themselves to experiment and observation, and 

 are all equally eager to arrive at truth. 



Taking the Neo-Darwinians first, we find the basis of their theory 

 to be this. Organic evolution depends on, and is carried out through, 

 the variations which- appear at the conclusion of the ontogenetic 

 development, i.e. at birth. This is the basis of their theory of organic 

 evolution. To the cp:iestion, What gives rise to those variations ? we 

 have as answers: — (1) Cause unknown (Darwin); (2) Chance — a 



17 NAT. SC. VOL. XV. NO. 92. 253 



