DO ANIMALS REASON? 485 



on the left side of the box (looking from within), and kept closed 

 by an ordiary thumb-latch placed fifteen inches from the floor. The 

 remainder of the front of the box was closed in by wooden bars. 

 The door was a wooden frame covered with screening. It was not 

 arranged so as to open as soon as the latch was lifted, but required 

 a force of four hundred grammes, even when applied to the best 



19 set. 



5cal 



e. 



Fig. 6. 



advantage. The bar of the thumb-latch, moreover, would fall back 

 into place again unless the door were pushed out at least a little. 

 Eight cats (JSTos. 1, 2, 3, 4, 5, 6, 7, and 13) were, one at a time, left 

 in this thumb-latch box. All exhibited the customary instinctive 

 clawings and squeezings and bitings. Out of the eight, all suc- 

 ceeded, in the course of their vigorous struggles, in pressing down the 

 thumb-piece, so that if the door had been free to swing open they 

 could have escaped. Six succeeded in pushing both thimib- 

 piece down and door out, so that the bar did not fall back 

 into its place. Of these, five succeeded in also later pushing the 

 door open, so that they escaped and got the fish outside. Of these, 

 three, after about fifty trials, associated the complicated movements 

 required with the sight of the interior of the box so firmly that they 

 attacked the thumb-latch the moment they were put in." 



In the cases of No. 1 and No. 6 the combination of accidents 

 required was enough to make their successes somewhat rare. Con- 



