38 Animal Intelligence 
will never be the use here. The word motive will always 
denote that sort of consciousness. Any one who thinks 
that the act ought not to be thus subdivided into impulse 
and deed may feel free to use the word act for empulse or im- 
pulse and act throughout, if he will remember that. t e act 
in this aspect of being felt as to be done or as doing is in 
animals the important thing, is the thing which gets asso- 
ciated! while the act as done, as viewed from outside, is a 
secondary affair. I prefer to have a separate word, impulse, | 
for the former, and keep the word act for the latter, which it 
commonly means. 
: Starting, then, with its store of instinctive impulses, — 
the cat hits upon the successful movement, and gradually 
associates it with the sense-impression of the interior of the 
box until the connection is perfect, so that it performs the 
act as soon as confronted with the sense-impression. The 
formation of each association may be represented graphi- 
cally by a time-curve. In these curves lengths of one milli- 
meter along the abscissa represent successive experiences 
in the box, and heights of one millimeter above it each 
represent ten seconds of time. The curve is formed by 
joining the tops of perpendiculars erected along the abscissa 
I mm. apart (the first perpendicular coinciding with the y 
line), each perpendicular representing the time the cat was 
in the box before escaping. Thus, in Fig. 2 on page 39 the 
curve marked 12 in A shows that, in 24 experiences or 
trials in box A, cat 12 took the following times to perform 
the act, 160 sec., 30 sec., go sec., 60, 15, 28, 20, 30, 22, 11, 15, 
20, 12, 10, 14, 10, 8, 8, 5, 10, 8, 6,6, 7. Ashort vertical line 
below the abscissa denotes that an interval of approximately 
24 hours elapsed before the next trial. Where the interval 
was longer it is designated by a figure 2 for two days, 3 for 
three days, etc. If the interval was shorter, the number of 
