DR. HILL, FROM REFLEX ACTION TO VOLITION. 43 



control, and self-development, whether upward or downward 

 in the ethical scale, have impressed npon it. This is a large 

 question, which would carry me far beyond the province of 

 this paper. At present evolutionists are divided into two 

 camps. Some hold to the older doctrine that under the 

 influence of the environment the organism acquires and 

 transmits tendencies favourable for its existence, while others 

 form the newer school, headed by Weismann, who believes 

 that acquired characteristics are not transmitted, but that the 

 " chance " differences between a number of individuals born 

 under the same conditions tend, when favourable, to improve 

 the individual's prospects in life, while unfavourable modifi- 

 cations diminish the likelihood of his holding his own in the 

 struggle for existence. This doctrine does not carry my 

 judgment with it ; it throws back the variations to chance as 

 an ultimate cause. Chance ! an expression which in science 

 can only stand for a cause not yet discovered. Weismann 

 proceeds a step further in his reasoning, and draws a wide 

 distinction between the reproductive cells and the rest of the 

 body in which they happen to reside. The body at large, he 

 says, plays no part in determining the structure of the off- 

 spring, and therefore no characters which it may acquire can 

 be transmitted. There is no logical difficulty in looking at 

 the central nervous system from this point of view, but it 

 appears to me that observation of human nature demonstrates 

 beyond a doubt that mental characteristics, peculiarities in 

 the form of the network which have been acquired by 

 individual occupation and effort, are handed on to offspring. 

 Theories of evolution are based as a rule upon the study of 

 external form, but it is undeniably true that if the disposition 

 acquired during life by the least of the strands of this incon- 

 ceivably complicated network is transmitted to a descendant, 

 Weismann's theory falls to the ground. 



Hypotheses with regard to its origin aside, the network 

 undoubtedly exists. It is first formed in connection with 

 sense organs, and probably never presents what can be 

 properly called a motor or " kinetogenetic " part. Its function 

 is the distribution of the sensory impulses which it receives 

 into their appropriate nerve fibres, which have their starting 

 points in the larger motor cells. 



Up to the present we have spoken of the transmission of 

 impulses as if it always occurred only after such delay as was 

 necessary for the transit through the nerve network. Another 

 step in evolution must now be recognized. It is impossible 



