MAZE STUDIES WlTH WHITE RAT 303 



Similar possibilities obtain for the function of smell in the 

 acquisition of the maze habit. The facts previously given 

 exclude, the hypothesis of operative effects for smell as well 

 as for vision. As between the directive and tonic hypotheses 

 no confident decision can be made. The records of the blind 

 rats indicate that smell exerts no directive function after the 

 maze is learned, but it is possible that olfactory controls may 

 be utilized in the formation of the habit and yet be noneffective 

 after the maze is mastered. The functions of smell and vision 

 compensate for each other in the learning process. This fact 

 is most easily interpreted on the basis that both senses have 

 the same function. Since vision is efficacious because of its 

 tonic effect, we would need to assume the same function for 

 smell. On this hypothesis, a certain amount of sensory stimula- 

 tion is necessary to induce sufficient motor activity requisite 

 for learning. This effect can be secured through either smell 

 or vision, while the elimination of both senses is disastrous. How- 

 ever, it is not entirely impossible to conceive that the two senses 

 may compensate for each other even though their functions are 

 different. One may suppose that vision exerts a tonic effect 

 while the function of smell is that of control. There is good 

 evidence that control is secured mainly through the medium of 

 the cutaneous and kinaesthetic senses. One may now suppose 

 that the cutaneous and kinaesthetic control requires a certain 

 amount of supplementation and that this effect may be furnished 

 by either the tonic function of vision or the additional control 

 exerted by smell. A final fact supports the tonic hypothesis 

 for both smell and vision. The blind and anosmic animals dif- 

 fered from the other groups in that they lacked persistence, 

 initiative and incentive. I refer to the fact that these animals 

 required help or additional stimulation in many of their trials. 

 One possible interpretation of this fact is obvious; we may 

 assume that these animals lacked a sufficient amount of sensory 

 stimulation to arouse the motor activity adequate to the situa- 

 tion. Their activity was deficient in vigor, decisiveness, and 

 persistence. These animals possessed the normal amount of 

 energy, and the proper kind of stimuli for the control and direc- 

 tion of this energy, but they were so deficient in their sensory 

 capacity that an adequate amount of this potential energy was 



