ENVIRONMENT AND EVOLUTION — KROPOTKIN. 413 



dry regions, we could not be persuaded that the unavoidable trans- 

 formation of leaves into prickles and spines in all plants immigrat- 

 ing- into a desert, or growing in a gradually desiccating region, 

 should count for nothing in the evolution of spiny species. We 

 could not believe that all the evolution of the so-called "adaptive" 

 structures in deserts, sea borders, Alpine regions, and so on, which 

 is going on in nature on an immense scale as a physiological result 

 of the conditions themselves, should leave no trace in the evolution 

 of the desert, sea-border, and Alpine species; that the adjustments 

 which are in the individual a direct consequence of the physico- 

 chemical action of the environment upon its living matter, should 

 have in the evolution of a species a merely accidental origin. 



Already then many biologists took the Lamarckian point of view ; 

 and very soon Darwin himself, after having gained what he con- 

 sidered to be the main point of his teaching — the variability of 

 species, 1 made the next step. He recognized the powers of the direct 

 action of environment in the evolution of new varieties, and even- 

 tually new species. The part of natural selection in this case was 

 to eliminate those individuals which were slow in acquiring the new 

 adaptive features, and to keep a certain balance in the evolution of 

 new characters. Its function was thus to give a certain stability 

 to the new variety. Of course this stability did not mean immuta- 

 bility. There being no immutable species, it meant only that the 

 new features would be retained for a certain number of generations, 

 even if the new variety was placed once more in new surroundings, 

 or was returned to the old ones. 



III. 



That changes produced in plants and animals by the direct action 

 of a changing environment are inherited was not a matter of doubt 

 for Darwin. He had carefully studied and sifted the experience of 

 breeders and cultivators, and he found in it ample proofs of such 

 an inheritance. He was aware, of course, that mutilations are not, 

 and can not be, inherited as such (this had been known, in fact, 

 since the eighteenth century) ; but he also knew that characters de- 

 veloped in a new environment were transmitted to the offspring — if 

 the modifying cause had acted upon a certain number of generations. 

 This last limitation was well known to both Lamarck and Darwin 

 and repeatedly mentioned by them. 



Having already discussed in a previous article the teachings of 

 Weismann, who opposed this view, I shall refer the reader to that 

 article 2 and only mention here and further develop one or two of 

 its points. 



1 See bis Lelters. 2 Nineteenth Century and After, March, 1912. 



