and cases like Brown-Sequard's guinea pigs, and results 

 like those of MacDougal with plants and of Tower with 

 beetles may lead us to alter the opinion stated. But as it 

 stands now most investigators hold that there are strong 

 general grounds for disbelief in the principle, and also 

 that it lacks experimental proof. 



The explanation of natural evolution given by Darwin- 

 ism and the principles of Weismann, Mendel and De 

 Vries, still fails to solve the mystery completely, and ap- 

 peal has been made to other agencies, even to teleology 

 and to "unknown" and "unknowable" causes as well as 

 to circumstantial factors. A combination of Lamarckian 

 and Darwinian factors has been proposed by Lloyd Mor- 

 gan, Mark Baldwin, and Professor Osborn, in the Theory 

 of Organic Selection. The Theory of Orthogenesis pro- 

 pounded by Naegeli and Eimer, now gaining much 

 ground, holds that evolution takes place in direct lines of 

 progressive modification, and is not the result of apparent 

 chance. Of these and similar theories, all we can say is 

 that if they are true, they are not so well-substantiated as 

 the ones we have reviewed at greater length. 



The task of experimental zoology is to work more 

 extensively and deeply upon inheritance and variation, 

 combining the methods and results of cellular biology, 

 biometrics, and experimental breeding. We may safely 

 predict that great advances will be made during the next 

 few years in analyzing the method of evolution ; and that 

 a few decades hence men will look back to the present time 

 as a period of transition like the era of re-awakened inter- 

 est and renewed investigation that followed the appear- 

 ance of the "Origin of Species." 



WE must now state distinctly and fairly the present 

 views of science regarding man's place in nature. Surely 



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