8i6 POPULAR SCIENCE MONTHLY. 



chief actors in the final triumphal stage of the theory, Darwin, 

 Spencer, and Huxley. His analysis is marked by a conspicuous 

 desire for fairness all round : he has honestly endeavored to 

 assign to each of these three great thinkers his own true share 

 no more, no less in the genesis of the modern evolutionary con- 

 cept. Yet, though the book contains, strictly speaking, little on 

 this head that was not already implicitly within the reach of spe- 

 cial students of the evolution of evolutionism, it will probably 

 prove a great surprise to that large section of the reading public 

 which habitually confines the idea of evolution to organic devel- 

 opment alone, and which still believes that Darwin " invented " 

 the theory of descent with modification. To all such people and 

 they include the mass of the averagely well-read Mr. Clodd's 

 revelation will come with all the charm of a sudden surprise. He 

 has been enabled through the kindness of Mr. Herbert Spencer to 

 give fuller and more authoritative details of the fundamental 

 facts than have yet been published; and he shows more fully 

 perhaps than any one else has hitherto done the central impor- 

 tance of Mr. Spencer's position in the evolutionary advance. 



May I begin with a passage which I quoted from one of Mr. 

 Spencer's own early works no less than eleven years since, in my 

 little monograph on Charles Darwin ? It occurs in an essay on 

 The Development Hypothesis, in that long-defunct paper, the 

 Leader. (The Italics are in the original.) 



" Even could the supporters of the development hypothesis 

 merely show that the origination of species by the process of 

 modification is conceivable, they would be in a better position 

 than their opponents. But they can do much more than this. 

 They can show that the process of modification has effected, and 

 is effecting, great changes in all organisms, subject to modify- 

 ing influences. . . . They can show that any existing species 

 animal or vegetable when placed under conditions different 

 from its previous ones, immediately begins to undergo certain 

 changes of structure fitting it for the new conditions. They can 

 show that in successive generations these changes continue, until 

 ultimately the new conditions become the natural ones. They 

 can show that in cultivated plants, in domesticated animals, and 

 in the several races of men, these changes have uniformly taken 

 place. They can show that the degrees of difference, so produced, 

 are often, as in dogs, greater than those on which distinctions of 

 species are in other cases founded. They can show that it is a 

 matter of dispute whether some of those modified forms are vari- 

 eties or modified species. They can show too that the changes 

 daily taking place in ourselves the facility that attends long 

 practice, and the loss of aptitude that begins when practice ceases 

 the development of every faculty, bodily, moral, or intellectual. 



