LECTURE I 



INTRODUCTORY 



In this course of lectures I shall give, on many questions, the 

 Scotch verdict of "not proven," and experience warns us that 

 this will be interpreted as an assertion that they are proved or 

 disproved, although no one can, in justice, interpret an admission 

 that a thesis may some time be proved or disproved as belief 

 that either of these things will come about, or as an admission 

 of anything else except a suspension of judgment, for all must 

 hold it the height of folly to found a scientific opinion on lack of 

 evidence. 



If I sometimes speak of things that are not commonly held to 

 fall within the province of zoology, — if I try now and then for 

 soundings in waters which able pilots tell us are far out of the course 

 of our ship, — I hope they who follow me to the end of our voyage 

 will admit that I have not wandered from our true course ; although 

 it may be well to show now, by way of introduction, how it is that 

 zoologists find themselves face to face with many problems which 

 other men of science have agreed to lay aside as insoluble or irrele- 

 vant. 



I shall try to show that life is response to the order of nature — 

 in fact, this thesis is the text of most of the lectures; but if it be 

 admitted, it follows that biology is the study of response, and that 

 the study of that order of nature to which response is made is as 

 well within its province as the study of the living organism which 

 responds, for all the knowledge we can get of both these aspects 

 of nature is needed as a preparation for the study of that relation 

 between them which constitutes life. Our interest in all branches of 

 science is vital interest. It is only as living things that we care to 



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