CHAPTER XIV 



A STUDY OF THE SENSES 

 1. THE SENSE OP TOUCH 



The Sense Organs of Touch. In our study of the skin we 

 found that small hillocks or papillae of the dermis project 

 outward into the epidermis, and 

 that within many of these 

 papillae are the terminations of 

 afferent (sensory) nerve fibers. 

 In some cases these terminals 

 take the form of minute swell- 

 ings on the nerve fibers; in 

 other papillae there are more or 

 less complicated tactile corpus- 

 cles, each composed of sensory 

 cells and a tangle of sensory 

 fibers. In many regions, also, 

 of the skin branching nerve 

 fibers pass out and end in little 

 knobs between the lower cells 

 of the epidermis. From these 

 terminations, whatever their 

 form or position, nerve fibers 

 extend to the central nervous 

 system, and so, by a relay sys- 

 tem of fibers, the external regions of the body are brought 

 into communication with the sensory cells of the spinal 

 cord and the brain., 



291 



FIG. 131. A Tactile Corpuscle 

 in a Papilla of the Dermis. 



a = knobs on the branches of a 



nerve in the papilla. 

 n = nerve fiber ending in papilla. 



