30 STELLA BURNHAM VINCENT 



one to the other indifferently. If the edges were made unlike, 

 if a low rail for instance, were put along one side, the behavior 

 of the rats might be affected in much the same way as by the 

 removal of the tactile hairs on one side. 



Experiment VI. Anosmia rats with and without vibrissae. 

 These rats w^ere males whose olfactory lobes had been removed 

 the last week in August. They were put in the maze the first 

 week in October 1910. The vibrissae were removed from three 

 of them but w^ere intact in two. 



The behavior of these animals as observed added nothing new 

 for the real purpose of this work. They were used merely as 

 controls since in the observation of the use of the nose it is im- 

 possible to tell whether it is being used as a tactile organ or for 

 smell. 



The records showed that the average time of the last ten 

 trials was as low as any set tried while the errors were about the 

 same as in the normal maze. A comparison of the rats with 

 and without vibrissae showed the usual thing. The time of 

 those where the vibrissae had been removed w^as one-half more 

 for the last ten trials and the number of trials taken in learning 

 was two-thirds greater. These rats, also suffered ten times as 

 many slips and falls as those which had their vibrissae intact. 



The curve showed a learning process which differed essentially 

 from some of the others. The error curve was disproportionally 

 high and almost entirely above the time curve. The curve 

 drawn from the figures of the rats without vibrissae was very 

 different from that drawn from those whose vibrissae were uncut. 



Shall we say this — smell is in all likelihood the intellectual 

 sense of these animals. When they are deprived of this, probably 

 their whole remaining sense reactions are somewhat lowered in 

 consequence. If the animals are in good condition otherwise, 

 there is no reason why their speed may not be as great as the 

 other animals, but they will make more errors in learning. 



Experiment VII. Rats with infra-orbital nerve cut on maze 

 without sides. In this group there were nine females. They 

 were operated upon the first week in May, 1911, brought up to 

 the laboratory May 14, fed in the maze May 21 to 24 inclusive 

 and put in the maze to run May 25. 



The infra-orbital branch of the fifth nerve was cut just before 



