CHAP. XIV 
FUNDAMENTAL PROBLEMS 
411 
evolution, and especially on Darwin’s presentation of that 
theory, to the bewilderment of the general public, who are 
cpute 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 ivhose 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 naturalists who minimise the agency of 
natural selection. (3) Dr. Karl Semper, ivho 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 will 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 
