20 THE FOUNDATIONS OF ZOOLOGY 



strata, far less to imitate, in the brain of the chick, any struct- 

 ural equivalent to its experience, we may be told that no one 

 expects complete inductive proof of any scientific generalization; 

 that he who refuses to admit that all water consists of HjO until 

 chemists have decomposed every drop of water in the ocean is 

 lacking in good sense; and that it is equally unreasonable to de- 

 mand the artificial imitation of all the responses of living things 

 before we admit that all response is mechanical. 



To this we must answer that no great harm can be done if 

 the chemist interprets the admission that we have not the slight- 

 est reason to doubt that every drop of water is decomposable into 

 hydrogen and oxygen as an assertion that all water is so decom- 

 posable, since, for all the ordinary purposes of chemistry, the 

 negative admission and the positive assertion may be treated as 

 if they were synonymous. The case is very different when the 

 subject under consideration is not chemistry, but the nature of 

 knowledge, for we are about to enter a field where we may easily 

 lose our way unless we distinguish inference from perception, to 

 the best of our ability. The utmost the physiologist is warranted 

 in asserting is that, for all one knows to the contrary, every 

 response may be mechanical; and I think all thoughtful students 

 must so far agree with him as to admit that belief that any of the 

 responsive actions of living beings are not mechanical is highly 

 unwise and precarious, in view of the condition and prospects of 

 modern physiology ; although we must, in my opinion, also admit 

 that not one single vital response has as yet been completely ana- 

 lyzed, or resolved, from beginning to end, into phenomena of matter 

 and motion ; for I am myself unable to discover, in the present 

 status of biology, any demonstration of error in the assertion that 

 life is different from matter and motion. 



However this may be, we know, by evidence which no one can 

 question, that many actions are attended by memory, and by con- 

 scious experience, and by volition and reason and a sense of moral 

 responsibility. Many beneficial responses are known to be judicious 

 and reasonable, and many voluntary acts are known to be right 

 or wrong. 



As these convictions seem, at first sight, to be contradictory to 

 the opinion that, for all we know to the contrary, all response may 



