FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 29 



The error curve when the cut had been made on the left drops 

 more rapidly but does not in the entire distance become uniform. 

 The time curves begin at about the same level but the one 

 where the cut has been made on the right — the more favorable — 

 side shows extreme irregularity as compared with the other 

 although unlike the other there is uniformity in the last fifth of 

 the curve. 



One is puzzled to account for some of these differences. The 

 higher time curve for the more favorable side no doubt comes 

 from a closer following of the edge a procedure which on that 

 side is tolerably successful. The big drops in this time curve 

 are possibly due to the dropping out of some of the by-ways 

 into which this habit of following the edges led the animal. The 

 following of the right edge although it took the animals around 

 the maze was not so successful as a whole and was earlier aban- 

 doned. But there was more of it to abandon and the cutting out 

 of errors did not occur so quickly although the time dropped 

 more rapidly. 



Rats can evidently make use of their vibrissae in solving their 

 problems. The long side hairs touch vertical surfaces, the short 

 curved ones, nearest the nares, the floor or ground as they run. 

 Or the animals can turn the long hairs down and follow along 

 edges and the act saves them many a slip and fall as the record 

 shows. ' 



If a rat runs out into the open it runs close against the sides 

 of house, wall, or walk. It does this instinctively, supposedly 

 from fear. From recent work upon animals we may conclude 

 that the vision of the white rat is poor. May not this habit of 

 keeping close to vertical surfaces be due to the fact that the 

 vibrissae of the rat serve much as a blind man's hands serve him 

 in a room or as his cane as he walks about the street. If a blind 

 man had lost his right hand he would naturally keep to the left 

 of the walk. A rat does not need his vibrissae to tell him the 

 size of holes, his ordinary cutaneous sensations are sufficient. 

 I have seen one of these rats squeeze through a hole an inch and 

 a quarter in width while the vibrissae of this same rat from side 

 to side including the head measured five inches. 



The animals in Experiment II were seen to make more use of 

 their vibrissae than under some other conditions but the two 

 edges of the narrow path were exactly alike and they went from 



