50 STELLA BURNHAM VINCENT 



hair and in what order they regenerated. Needless to say all 

 of these things were not established but in testing these points 

 were kept in view. 



For stimulation the point of a dissecting needle, of a pencil, 

 the heated end of a blunt probe and ice were used. It was soon 

 found that the animal's eyes must be kept covered in order to 

 be certain that it was not reacting through vision. As a rule 

 the rats, which were thoroughly tame, were held in one hand 

 so that the fingers covered the eyes and the other hand was used 

 in testing. The conclusions of the experimentator were checked 

 up by those of others in the laboratory. 



No animal tests of this kind can have the \'alue possessed by 

 human tests but they are interesting by way of comparison and 

 necessary in this case as a control for the behavior experimenta- 

 tion. The following notes are those of a typical animal to which 

 are appended a few notes selected from those taken from the 

 animals used in the discrimination tests. 



Rats operated Tuesday, Sept. 12. Both infra-orbital nerves 

 cut. Ten minutes later climbed out of the box. Tested an hour 

 later — no sensitiveness in upper lip or nose. 



Monday, Sep. 18. Tested again this morning. No apparent 

 sensitiveness to pulling hair, brushing hair, or to touching upper 

 lip or end of nose with point of a needle even if the needle were 

 pushed into the skin but the animal flinched every time the 

 interior of the nostril was touched or the lower lip. It also 

 sometimes moved its head when the upper lip was touched but 

 with a slow movement quite unlike the quick jerk given when 

 the lower lip was touched and never made this movement when 

 the eyes were covered. Did not react in any way to needle 

 pricks on these parts when the eyes were covered although the 

 point of the dissecting needle was pushed far in. Tried a heated 

 probe, so hot that it blistered the finger but it produced no 

 effect neither did ice. 



Sept. 23, (11 days). Lips still insensitive to pain or touch 

 by point of compass or from pulling of hairs. On the left side 

 there are only four long hairs. Five are broken off short. The 

 short hairs toward the tip of the snout are bent and curled as 

 if dead and pull out very easily. On the right side there are 

 10 long hairs, two broken ones and the short hairs near the 

 tip of the snout resemble those on the other side. Some of 



