74 L. W. SACKETT 



remembering it, or, what he calls "sense modalities in the pro- 

 cess of learning and retaining." By surgical and chemical means, 

 he destroyed hearing, sight, smell and touch, the last, however, 

 as mediated through the vibrissae and the soles of the feet. 

 Still his rats knew the maze after learning it and could even 

 learn it without any one of these senses. He could not, how- 

 ever, destroy all of the senses in the same rat at the same time 

 without destroying metabolism and kilHng the animal. In 

 eliminating one sense at a time, he still leaves room for the 

 hypothesis that learning is accomplished by the sum of the 

 influence of all the senses. The elimination of one may leave 

 a remainder large enough to be effective without very much 

 deterioration of power. Watson could not, by means of mutila- 

 tion eliminate the kinaesthetic sense. It was just this sense 

 which the present experiment attempted to modify and which 

 the latter portions of curves in plate IV represent. The maze 

 was situated in the open, on a slope of about lo degrees with 

 the entrance at the lower side. After porcupine No. 3 had been 

 through 49 times and had attained to the perfection of one 

 error in blind alley 7 and an occasional misstep into j, the maze 

 was moved 18 inches down the hill, changing all the paths, but 

 in no way effecting their slope or direction. No. 3 was then 

 placed into the maze for the 50th trial. He traversed it with 

 two errors in 2 minutes, 30 seconds whereas his time was 

 usually below one and one-half minutes (A' plate IV). He 

 moved with a great deal less certainty, but this was most prob- 

 ably due to the change of tactual stimulation of the feet. On 

 the second trip the same day he moved with much more certainty 

 and much greater speed. This greater speed threw him into 

 three blind alleys and slightly increased his time. On the follow- 

 ing day, both trips were made with the characteristic turn into 

 7. Shifting the maze had not materially disturbed his ability. 

 Before the 54th trial the maze was rotated through 90 degrees 

 clock-wise thus changing the direction and relative slope of 

 every path. The result was that his time increased from i 

 minute 8 seconds to 32 minutes 38 seconds and his errors 

 from I to 71, (B' plate IV), and he was so completely lost 

 that he missed 7 for the first time in his experience. The porcu- 

 pine spent most of his time, on the first trial after rotating, in 

 the first half of the maze. On the next trip his time was in- 



