42 STELLA BURNHAM VINCENT 



There was little trouble in the beginning and falls only began 

 to occur as the rat increased in speed. In other animals, par- 

 ticularly those without vibrissae, this was not seen in anything 

 like the same degree. There was extreme caution and fewer 

 falls in the first trial or two but falls occurred when the speed 

 was slow. 



Second, these accidents may have been brought about by 

 the incoordination resulting from the emotional conditions 

 which were produced by the first fall. If this were the cause, 

 why were not all groups affected equally and why were other 

 signs of such disturbance not more evident? 



Third, they may have been due to vertigo. Vertigo may 

 come from labyrinthine, optical, or Weil says,^' tactile disturb- 

 ances. Labyrinthine trouble must be excluded as it would 

 scarcely affect whole groups of animals and there are no signs 

 of it in the natural and free climbing of these animals, \'ision 

 is scarcely good enough to function in any such signal way and 

 finally there were no known tactile disturbances except those 

 brought about by the cutting of the vibrissae. 



Fourth, they may have been due -to the insufficient data for 

 equilibration — what Bastian calls "guiding sensations." "* Vision 

 plays a leading role in human locomotion and it may be sup- 

 posed that it has important functions in animal locomotion. 

 The rat then with its poor sight is at a disadvantage of which 

 the records of the blind rats may be a fairly accurate measure. 

 The only other deficient sense of which we are cognizant in 

 these rats was the lessened tactile sensations coming from the 

 mouth caused by the removal of the vibrissae. This will be 

 referred to again in a moment. 



It happened at this time that Dr. J. G. Wilson was engaged in 

 some research upon the semicircular canals and animals, in- 

 cluding white rats, were available for observation with one or 

 both labyrinths destroyed. A rat with one labyrinth destroyed 

 revolves to the side of the lesion and in walking tends to circle 

 to that side. When both labyrinths are destroyed it lies flat- 

 ened with limbs extended, clutching support. It cannot main- 

 tain itself on a narrow support by clasping it with its limbs 

 as normal animals do. This ability returns about the same 



1' Weil 2: Des Vertiges, Paris, 1886, Quoted by Morat, Physiol, p. 612. 

 >s Bastian, H. C: The Brain as an Organ of Mind, 1891, p. 543. 



