THE DIRECT ACTION OF ENVIRONMENT AND 



EVOLUTION. 1 



Prince Kropotkin. 



There can be no doubt that species may become greatly modified through the 

 direct action of environment. I have some excuse for not having formerly 

 insisted more strongly on this bead in my Origin of Species, as most of the best 

 facts have been observed since its publication. — Darwin, Life and Letters, iii. 232. 



When we cast a general glance upon the work accomplished during 

 the last half century in connection with the theory of evolution, we see 

 that the question which underlay most of the theoretical discussions 

 and inspired most of the study of nature and experimental research 

 was the great fundamental question as to the part played by the direct 

 action of environment in the evolution of new species. This question 

 was one of the absorbing thoughts of Darwin in the later years of 

 his life, and it was one of the chief preoccupations amongst his 

 followers. 



A mass of researches having been made in this direction, I analyzed 

 them in a series of articles published in this Review during the last 

 seven years. Beginning with the evolution of the conceptions of 

 Darwin himself and most evolutionists about natural selection, 2 1 next 

 gave an idea of the observations and experiments by which the modi- 

 fying powers of a changing physical environment were established 

 beyond doubt. 3 Then I discussed the attempt made by Weismann to 

 prove that these changes could not be inherited, and the failure of this 

 attempt. 4 And finally I examined the experiments that had been made 

 to ascertain how far the changes produced by a modified environ : 

 ment are inherited. 5 What we have to do now is to consider the con- 

 clusions which may be drawn from all these researches and discus- 

 sions. 



I. 



When Darwin was leaving England for a cruise in the Beagle he 

 was warned by one of his friends that he must not let himself be 



1 Reprinted by permission from The Nineteenth Century and After, January, 1919. 



2 Nineteenth Century and After, January, 1!)10. 



•" "The Direct Action of Environment in Plants'," July, 1910 ; and " The Response of 

 Animals to their Environment," November and December, 1910. 



4 " Inheritance of Acquired Characters : Theoretical Difficulties," March, 1912. 



5 " Inherited Variations in Plants," October, 1914 ; and " Inherited Variations in 

 Animals," November, 1915. 



409 



