CHAPTER XXVIII 

 THE SENSES OF TOUCH, TASTE AND SMELL 



Introductory. It is one of the functions of the nerve system to bring 

 he individual into conscious relation with the external world. This is ac- 

 -omplished in part through the intermediation of afferent nerves, connected 

 Iripherally with highly specialized terminal organs, and centrally wit. 

 ,necialized areas in the cerebral cortex. 



Excitation of the terminal organs by material changes in the environment 

 develops nerve impulses which, transmitted to the cortical areas, evoke 

 Usatfons. These sensations, differing in character from those vague ill- 

 defined sensations-^., fatigue, well-being, discomfort, etc -caused .by 

 changes occurring within the body, are termed special sensations- 

 temperature; taste; smell; light and its varying 

 , hue, and tint; sound and its varying qualities, intensity, 



special sensations are 



optic, and auditory. Each mechanism responds MX 



stimulus and to no other. Thus, the stimulus for the 



kvr>itci tirn nf thp different mecnamsms. 



CALlLcttlUil Ui tiAv/ vj. L j_i. ^ j. ^ 



TVi f t involved in the production of the sensations inciuue ^i; a 



" " " of the 



peripheral org.n-.ith . ''' ni.lll co.te* in 



0, ,he 

 the ^'''" e h.tevet their character- 



object in comparison with former expenences. 



J 660 



