160 THE SENSE OF TOUCH IN ANIMALS 



same curved ridge, as cd, than when they he so that it joins 

 two different ridges, as ef. 



This illustration of experiment made on the patterns of man's 

 hand will serve to show that the sense of touch is most usefully 

 assisted by the arrangement of the papillary ridges into patterns, 

 and it is to be hoped many further such researches will be made. 



Functions of PapillcB of the Corium. — Whatever different 

 views may be held as to the primary, secondary, or even tertiary 



Fia. 174. — Diagram copied from memoir by Schlaginhaufen, illustrating certain 

 points in connection with the sense of touch. 



functions of the ridges, there can be no doubt of the fact that 

 the essential organ of touch of mammals resides in the papillary 

 layer of the corium. Though among the papillae some are 

 vascular only, this does not alter the fact that this layer of 

 the skin is primarily tactile, and the numerous sections of skin 

 which have been shown are sufficient to indicate a great varia- 

 bihty in the elaboration of the papillse in different animals. It 

 is in these papillae of the hand and foot of man that the special 

 tactile corpuscles of Meissner are found, though they also occur 

 in some other regions of the human body, as the bed of the 

 nails, the flexor surface of the forearm, the skin of the nipple, 

 the conjunctiva at the edges of the lids, and in the mucous 

 membrane of the tip of the tongue. All of these are regions 

 with a delicate tactile sense highly valuable to its possessor. 



