158 EVOLUTION AND MAN S PLACE IN NATURE 



ence from analogies of bodily structure. When re 

 ferring to the analogy in fissures and folds of the 

 brain of the orang and of man, and remarking that 

 they do not perfectly agree, Darwin adds, Nor could 

 perfect agreement be expected, for otherwise their 

 mental powers would have been the same. There 

 is a fallacy here, seriously affecting the whole argu 

 ment. Inference from structure to intelligence or 

 from intelligence to structure is not warranted on 

 evidence. Intelligence has not been scientifically 

 traced to structure, as sensibility has been, as co-ordina 

 tion of impressions has been, as excitation of motor 

 action has been. In accumulating evidence for the 

 doctrine of continuity, we have not been able to in 

 clude the phenomena of intelligence. These pheno 

 mena are not even known by study of organism ; and 

 have not been classified with structural functions. 



There is, indeed, little wonder that success in 

 working out a theory of continuity of organism, has 

 stimulated expectation that the law of continuity 

 would yet include intelligence also. But a belief of 

 this kind has no scientific value. Science depends 

 on evidence, whereas evidence in support of this 

 belief is not at command. We have been guided by 

 embryology, by rudimentary organs, by homological 

 construction of the whole frame in bones, muscles, 

 and sense organs ; by evidence for structural modi 

 fication under a laAv of natural selection, favoured 

 by the law improving structure by its use, and by 

 clear proof in favour of localisation of sensory and 

 motor centres in the brain. But in all this there 

 is no trace of evidence in support of the admitted 

 fact that a measure of intelligence belongs to the 



