CHAP. XIV FUNDAMENTAL PROBLEMS 411 



evolution, and especially on Darwin's presentation of that 

 theory, to the bewilderment of the general public, who are 

 quite unable to decide how far the new views, even if well 

 established, tend to subvert the Darwinian theory, or whether 

 they are really more than subsidiary parts of it, and quite 

 powerless without it to produce any effect whatever. 



The writers whose special views we now propose to 

 consider are: (1) Mr. Herbert Spencer, on modification of 

 structures arising from modification of functions, as set forth 

 in his Factors of Organic Evolution. (2) Dr. E. D. Cope, who 

 advocates similar views in detail, in his work entitled The 

 Origin of the Fittest, and may be considered the head of a 

 school of American natui'alists who minimise the agency of 

 natural selection. (3) Dr. Karl Semper, who has especially 

 studied the direct influence of the environment in the whole 

 animal kingdom, and has set forth his views in a volume on 

 The Natural Conditions of Existence as they Affect Animal Life. 

 (4) Mr. Patrick Geddes, who urges that fundamental laws of 

 growth, and the antagonism of vegetative and reproductive 

 forces, account for much that has been imputed to natural 

 selection. 



We will now endeavour to ascertain what are the more 

 important facts and arguments adduced by each of the above 

 writers, and how far they offer a substitute for the action of 

 natural selection ; having done which, a brief account Avill be 

 given of the views of Dr. Aug. Weismann, whose theory of 

 heredity will, if established, strike at the very root of the 

 arguments of the first three of the writers above referred to. 



Mr. Herbert Spencer'' s Factors of Organic Evolution. 



Mr. Spencer, while fully recognising the importance and 

 wide range of the principle of natural selection, thinks that 

 sufficient weight has not been given to the effects of use 

 and disuse as a factor in evolution, or to the direct action 

 of the environment in determining or modifying organic 

 structures. As examples of the former class of actions, he 

 adduces the decreased size of the jaws in the civilised races 

 of mankind, the inheritance of nervous disease produced by 

 overwork, the great and inherited development of the udders 

 in cows and goats, and the shortened legs, jaws, and snout in 



