THE WHITE RAT AND THE MAZE PROBLEM 141 



odor it serves to mark off a strange animal or give warning 

 of an enemy. 



Rats are omnivorous and hence there can be slight necessity 

 for any fine discrimination in the way of foods. A generalized 

 response to food odor will be all sufficient. I have, indeed, 

 never seen in white rats any clear discrimination of foods which 

 might be said to depend upon smell and have failed to find any 

 mention of such power by others. If food be introduced into a 

 cage unobtrusively, a rat usually stumbles over it before dis- 

 covering it. It might be supposed that blind and normal rats 

 would show different behavior in food seeking, yet in some 

 preliminary experiments covering several weeks, the food in 

 every instance, by both normal and blind rats, was apparently 

 found accidentally. The animals were very tame and were very 

 hungry. The food used was nuts, cheese and milk soaked bread. 

 The experiments, although significant, were too brief to be 

 conclusive. The instances which Small 2 cites of the reactions of 

 very young animals to different odors may clearly depend upon 

 the chemical sensitivity of the mucus membrane of the nostrils 

 and must be sharply distinguished from olfaction proper. Pro- 

 fessor Watson, 3 however, found that blind animals, otherwise 

 normal, were affected by odors to which anosmic animals failed 

 to respond. To repeat, smell is more closely associated with 

 food getting than is any other sense; yet it may be safely assumed, 

 and we should expect to find, that the sense is less refined in 

 animals which do not pick and choose their food than in those 

 which do. 



If a rat from another group is introduced into a cage containing 

 other rats they "nose" the whole body of the stranger. The 

 rats do not appear to get the odor across the cage for the excite- 

 ment and characteristic actions begin only with contact. Rats 

 also respond by different behavior to strange handling. No 

 doubt a large part of the excitement is due to different methods 

 of lifting, etc. ; but after the emotional disturbance is allayed 

 the "nosing" of the hand seems to indicate an odor stimulation 

 also. The power to follow a trail is usually supposed to depend 

 upon slight traces of body odor which remain upon the path which 



2 Small, W. S. Notes on the psychic development of the young white rat. Am. 

 Jour, of Psych., 11,89. 



3 Watson, J. B. Kinaesthetic and organic sensations, etc. Psych. Rev. Mon. 

 Sup., 8, no. 2, p. 65. 



