76 BIOLOGICAL LECTURES. 



to set off the reaction associated with the vague total situation, 

 that horses are trained to stop at " Whoa ! " and to turn at the 

 slightest pull of the rein, etc. It is in any particular case a 

 concrete problem how far you can change the external situation 

 and still secure the reaction associated with it. By such grad- 

 ual modification as we make use of in training domestic animals 

 you can of course change it without limit. For our present 

 purposes we need not bother with any instances of this problem, 

 remembering only that the animal does not react to a well- 

 defined, hard-and-fast feeling or notion of its surroundings, nor 

 with an immutable act, much less does it react to a well-defined 

 feeling of the essentials (for its purpose) in the situation, and 

 that therein lies the explanation of a host of animal activities. 

 So much for the feelings which are the first element in the 

 association. Somewhat must now be said about the " impulses." 

 I have all along spoken of impulse and act, because for various 

 reasons out of place in this discussion I believe that there is 

 in one of these associations, besides the feeling of the situation 

 and the resulting act, a feeling preparatory to that act, such as 

 we ourselves feel in connection with any non-automatic muscular 

 performance. Such a feeling is meant by the word " impulse." 

 It does not, in my usage, mean "motive" or "desire," or even 

 the idea of the act to be performed, but merely the, in our own 

 case, rather evanescent feeling of doing. Whoever wishes may 

 discard this feeling from consideration, and substitute for 

 "impulse and act" the word "act" alone, and refer what is 

 said in the rest of this paragraph about the former to the latter. 

 In the cases so far considered, the causes of the impulses and 

 acts manifested at the first experience of a certain situation 

 have been, apart from accident, the instinctive tendencies of 

 the animals in question. That was because the particular 

 situations chosen (the pen for the chick, box for the kitten, etc.) 

 were situations for which the animals' previous experiences had 

 given them no preparation. But suppose us to take the kitten 

 that had formed an association between confinement in that 

 box and the act of clawing at a certain place and put it in 

 another box. We would witness less biting and squeezing and 

 more clawing than we did in our previous experiment. For its 



