302 Journal of Comparative Neurology and Psyehology. 



A description of the development of the habits in the 

 young, on a subsequent page, will, I think, show that most of 

 the habitual reactions of the guinea pig are of the instinctive 

 type. Fear of specific objects is probably not instinctive ; re- 

 action to warning cries seems to be acquired from the mother 

 after birth ; and domestication leads to the modification of some 

 sounds, and probabh-, to a certain extent, to a partial inhibition 

 of running and jumping activities. 



The guinea pig is a social animal. When several are put 

 into a cage they huddle together in one corner, and when they 

 are alone in contiguous cages with wire partitions between them, 

 they are generalh' to be seen as close together as the wire will 

 permit. 



As a rule there seemed to be greater activit}' in the dark 

 than in the light, more freedom of movement being present. 

 Several times I noticed when the light was turned out the 

 animal would immediately begin to eat. This observation 

 is confirmed by a remark of Ernst vox Friedl, who, in speak- 

 ing of the guinea pigs' natural habits, says "They lie down in 

 the long, dry grass where they live, and keep concealed most 

 of the day. They are more night than day animals. " ^ The 

 possible differences in activity in the dark as compared with 

 light has been borne in mind during experimentation. 



The note of warning is a sharp cr}-. Usually it is uttered 

 when any dark object passes the window. Once or twice I 

 have known it to be given when a shrill whistle sounded near 

 by. Man}- visual stimuli will call it forth. At first my reach- 

 ing m}- hand to turn on the electric light overhead caused the 

 note of alarm — not of fear. The cry produced instant quiet 

 throughout the room. I have not heard it responded to except 

 by a mother with }-oung who utters a v^ery low "burr-r-r" to 

 them and thus quiets them. The cry of fear is loud and shrill, 

 seeming to indicate nothing of caution or concealment, while the 

 alarm call is softer and more deliberately uttered. Guinea pigs 



' Friedl. Zur Familien.s- und Lebens-Geschichte des Meersclnveinchens, 

 Cavia cobaya, Marcgrave. Zoologische Garten, April, 1889. 



[ 10] 



