FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 43 



time as the power of locomotion but in regaining this abiHty 

 to walk it is very slow, much slower than a dog. This is men- 

 tioned because it has been noted before in the experimental 

 work that the equilibrium of the rat seems unstable. 



The day after the operation if the animal were placed on its 

 back, a proceeding which it resisted forcibly, when released it 

 righted itself with a spring which was machine-like in its quick- 

 ness and perfection : in other words it was an unimpeded reflex. 

 The normal animal rights itself but its movements show more 

 variation in control. This animal's feet were now anaesthetized 

 with ethyl chloride and it was again placed upon its back, where 

 it remained unresisting until the effect of the anaesthetic had 

 passed oft'. It is known that a frog from which the cerebral 

 hemispheres have been removed can maintain its usual attitude 

 so long as the afferent impulses from its feet are unaffected 

 but if these be abolished it falls at once. A part of the disturb- 

 ance in equilibrium in locomotor ataxia is said to be due to 

 the loss of tactile sensations from the feet. 



One more illustration. Among these rats was a blind rat 

 whose labyrinth had been destroyed. It moved about as easily 

 as those that saw but circled to the side opposite the injury. 

 The only explanation which can be offered of this behavior is 

 that as the seventh nerve was cut in the operation and there- 

 fore the vibrissae, although sensitive, were motionless on the 

 injured side, the blind animal, which relied more on these organs 

 as guides in locomotion, turned naturally to the side where they 

 were more efficient. 



Afferent impulses from the skin of the feet and the vibrissae 

 of the head seem to be important elements in equilibrium and 

 locomotion. They function as a constant factor in preserving 

 posture and any break or change in these impulses is the stim- 

 ulus to quick reflexes which serve to regain the attitude or 

 stable position. Over these impulses the labyrinth appears to 

 exert a controlhng, inhibiting effect as is shown in the machine- 

 like movements of the animal when cut off from this influence, 

 but if now the afferent stimulus be abolished by anaesthetics 

 the reflex fails. The stimulus to the righting movements of the 

 rat without labyrinths comes from cutaneous impulses from 

 the feet and not from the stimulation of the nerve endings in 

 the back upon which it is laid or from the stimulation of the 



