466 Proceedings of the Eoycd Physical Society, 



Goetlie, with greater concreteness, spoke quite definitely 

 about the modifying influence of food, light, humidity, and 

 the like. Lamarck (1802) developed the same opinion as 

 Erasmus Darwin, and regarded changes in surroundings as 

 prompters of change in function, which was to him the all- 

 important factor. In marked contrast to Lamarck stands his 

 contemporary, Treviranus (1802), who insisted with greater 

 wealth of illustration on the direct hammering action of the 

 environment. Geoffroy St Hilaii-e (1830) swung round to a 

 strictly Buffonian position, and regarded the direct action of 

 external forces as the all-important factor in modification. 

 Eobert Chambers (1843) allowed that physical forces in some 

 way governed the process, especially in their action on the 

 generative system. 



In 1852 Spencer combined the views of Buffon and 

 Lamarck, maintaining that "under new conditions the 

 organism immediately begins to undergo certain changes in 

 structure, fitting it for its new conditions." If the new in- 

 fluences persist, the changes in the organism are confirmed 

 in continued function, and perpetuated in heredity. 



Up to this point in the history it had been suggested that 

 variation might be either organismal, or environmental, or 

 functional, arising («) from within, because of the complexity 

 of the organism itself; (h) from without, in response to 

 external hammering; and (c) in the course of functioning. 

 It had been supposed by the small minority of those who 

 accepted the theory of descent, that variations arising in one 

 or all of these ways accumulated, so as to give rise to adapted 

 and progressive species. It was at this stage that Darwin 

 fulfilled the prophecies of Wells, Matthew, and others more 

 or less obscure, by expounding the principle of natural 

 selection. He did not definitely attack the primary problem 

 of the origin of variations ; he assumed their occurrence as 

 due to all but hopelessly complex causes. JSTot that he denied 

 preceding theories of variation and accumulating adaptation ; 

 he only asserted their insufficiency. He called in the aid of 

 the environment, both animate and inanimate, for a different 

 purpose, namely, to shear off in the struggle for existence the 

 majority of variations which were unfit, and to leave the 



