64 BIOLOGICAL LECTURES. 



around, they may call forth the activity quite as well. Other 

 " perversions " may be brought about by naturally or artificially 

 caused inhibitions. There may also, of course, be in animals, 

 as there may be in men, abnormalities in the nervous system 

 which may occasion abnormal instinctive manifestations. These 

 would need separate treatment. The interest of the ordinary 

 "perversions" is simply their witness, first, to the subordination 

 of instincts to the laws of nervous activity in general, e.g., vari- 

 ation, association, inhibition, and, secondly, to the coarse, rough- 

 hewn nature of many instincts. 



So much for the important general facts about how animals 

 meet situations apart from experience. Before entering on the 

 tasks of justifying the definition of instinct, which I asked you 

 to accept provisionally, and of saying somewhat about the 

 origin and evolution of instincts, I wish to take this opportu- 

 nity to advocate the study of instinctive activities by students 

 of elementary biology. Their observation requires no knowl- 

 edge of psychological terminology, no ability to make psycho- 

 logical interpretations. The observer has simply to answer 

 the question, " How does an animal react to a certain situation 

 the first time he is in it ? " The demonstration of every matter 

 discussed so far in this paper may be effected at practically no 

 expense in any quiet place where the student can find twenty 

 square feet of space in which to keep a few chicks. Such 

 study will serve as a partial corrective to the tendency to make 

 biology a study, not of life, but of form. It may give the stu- 

 dent a taste of and for fact in this field of biology, which will 

 keep him from getting lost when he meets with the specula- 

 tions about instinct. It is, moreover, worth while for its own 

 sake. 



Returning now to the question of definition, it is clear that 

 any one has a logical right to name things to suit himself and 

 to determine the particular things which he shall denote by a 

 certain word at his own sweet will, so long as he is clear and 

 consistent and does not reason from any other meaning of the 

 word than that he has given to it. One might, for example, in a 

 study of fission call Paramcecium " Hylobates McKinleyensis " 

 and commit no logical error, provided his figures showed clearly 



