3o8 Journal of Comparative Neurology and Psychology. 



The little ones were placed at x, 24 inches from the open- 

 ing j'. The mother was plainly visible through the wire, and 

 could probably have been smelt by a sensitive nose. But she 

 seemed to provide no stimulus leading to definite purposive ac- 

 tivity. The young guinea pig gnawed a little at the wire ; 

 probably an instinctive reaction, for there seemed to be no rec- 

 ognition of the proximity of the mother, i. e., no association 

 was yet set up between the sight of the mother in this en- 

 vironment and the satisfaction of hunger, if hunger were pres- 

 ent. Another female was put in the place of the mother, and 

 the attitude of the young remained unchanged. When the 

 young one was replaced in its home cage, it immediately found 

 its mother and began to suck. The other female w^as substituted 

 for the mother and the little one attempted to suck her. 



At 38 hours the guinea pig squeal in its infantile form is 

 fully developed. Movements are almost as well coordinated as 

 in the adult and there is great activity. The movements about 

 the cage are similar to those of the adult while hunting food. 

 The fore feet creep forward, the bright eyes are on the alert, 

 the belly is flattened to the ground, and the hind part of the 

 body is dragged forward. 



The peculiar movement of the guinea pig, so characteristic 

 of the first three weeks of existence, begins to appear on the 

 second day. I can attempt only a description of the move- 

 ment ; what its significance may be, why it arises and disap- 

 pears as it does, and what form it assumes in the adult I do not 

 know definitel}'. The guinea pig will run for a few steps, then 

 give a sudden jump forward or in some other direction, then 

 run and jump again. The jump may not be preceded by a run- 

 ning movement ; it may be forward close to the ground, or 

 shorter and somewhat more in the air. The jump is so sudden 

 and v'iolent as to be quite startling. It reminds one of the play- 

 fulness of a little calf kicking its heels. For some days this is 

 almost the only method of locomotion. It is probably a sign 

 of superfluous activity conspicuous in young animals ; and the 

 sudden zig-zags of the course may have facilitated escape at a 

 time when movement could not be inhibited. 



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