TOUCH, TEMPERATURE, MUSCULAR SENSE. 481 



up into the epidermis, which papillae cause the character- 

 istic arrangement of the fine lines so readily discernible in 

 the palm of the hands and fingers. Some of the papillae 

 contain blood-vessels, but the majority of them contain 

 touch corpuscles so that by examining these little ridges on 

 the hand one is able to trace real rows of these tactile cor- 

 puscles imbedded just beneath. They are quite small, be- 

 ing only 3^0" of an inch in length. In outline they are oval 

 and consist of a capsule of connective tissue fibers wound 

 round and round. One or more nerve fibers reach each 

 corpuscle, and after making several turns around it enter 

 the capsule losing at that point their medullary coats. The 

 axis cylinder, however, penetrates the connective tissue 

 capsule, branches several times and ends in little bulb- 

 shaped enlargements among the meshes of the same. 



Possibly the explanation of the action of all these end 

 organs lies in the fact that any pressure on such a corpuscle 

 would be much more likely to be transmitted by it to the 

 contained nerve, just as fingers placed between two boards 

 would be much more likely to notice an increase of pres- 

 sure near them than if not so situated. 



A very interesting form of touch corpuscles, although 

 not found in the human body, occurs in the beak of certain 

 birds, such as the duck. A corpuscle here consists of a 

 capsule of connective tissue in which lie several cuboidal 

 cells one above the other somewhat like several bricks 



n 



Fig. 153. CORPUSCLE OF GRANDRY FROM THE DUCK'S TONGUE. (After Izquierdo.) 

 n, nerve. 



might be stacked in a row. A nerve penetrates the cap- 

 sule and sends off branches which finally end between these 

 cells. No doubt a pressure transmitted to this corpuscle is 



