The Senses. 319 



animal acquainted with its surroundings. In the lips, 

 where we find the most exquisite sensibility, this sense is 

 developed not only for the purpose of distinguishing the 

 different varieties of food, but for ordinary touch purposes, 

 the lips of animals corresponding to our fingers. In the 

 horse the nerves supplying the long papillae of the skin of 

 the lips run to their extreme termination, the papillae being 

 thrown as finger-like processes into the substance of the 

 epithelial layers, and almost reaching to the free surface. 



The tactile sensibility in the foot of the horse enables 

 him to be acquainted with the nature of the ground over 

 which he is travelling, though that this is not absolutely 

 essential to his safety in progression, is proved by the results 

 of plantar neurectomy. I have suspected the presence of, 

 but not yet found, definite touch organs in the foot. 



The long feelers, or hairs, growing from the muzzle are all 

 endowed with extreme sensibility; this is brought about 

 through their close connection with the nerves of the 

 skin. 



We cannot explain why it is that the different impressions 

 of touch or pain can be so accurately defined by the pecu- 

 liarity of the impression conveyed. The impression of a 

 prick, a cut, or a burn, touch, itching, etc., produce unmis- 

 takable evidence of the nature of the substance causing the 

 impression. 



Through the nerves of the mucous membrane of the 

 mouth impressions are carried to the brain, impressions 

 which in horses convey unmistakable evidence to the animal 

 of the strength of will or weakness of his rider. 



