268 Animal Intelligence 
changed. Something must have been added to or sub- 
tracted from it. In Professor Jennings’ own words, “Since 
the external conditions have not changed, the animal it- 
self must have changed” (zbid., p. 286). And in adaptive 
learning something related to the results of the S A con- 
nection must have changed it. 
The series A— B—C—D does not become the series 
A—D or A—B!—C!—D by magic. If B and C are 
weakened and D is strengthened as sequents of A in re- 
sponse to S, it is because something other than repetition 
acts upon them. Repetition alone could not blow hot 
for D and cold for B. 
Moreover, as a mere matter of fact, ‘the resolution of one 
physiological state into another” through intermediate 
states does not with enough repetition ‘“‘become easier so 
that in course of time it takes place quickly and spontane- 
ously.” 
Paramecium does not change its response to, say, an ob- 
stacle in the water, from swimming backward, turning to 
one side and swimming forward by abbreviating and even- 
tually omitting the turn and the backward movement. 
The schoolboy does not tend to count 1, 2, 10 or to say 
a, b, z, or give ablative plurals after nominative singulars. 
Repetition of a series of physiological states in and of it- 
self on the contrary makes an animal increasingly more 
likely to maintain the series in toto. It is hard to give the 
first and then the last word of an oft repeated passage like 
Hamlet’s soliloquy or the Lord’s Prayer, or to make readily 
the first and then the last movement of writing a name or 
address. Repetition never eliminates absolutely and elim- 
inates relatively the Jess often or less emphatically connected. 
Even if supplemented by the law of effect, so that some 
force is at hand to change the effect of S upon the animal 
