Till PROPERTIES OP I \' M PART OF Mil REFLEX \K< 



791 



to finer grades of stimulation. Bj it we can feel the 1 i *_r 1 1 1 ♦ • s. t touch and 

 can discriminate, tin- finesl grades of temperature between 26 and 37 I 

 The power of localization of the stimulus and the ability to discrimii 

 between two points also return with epicritic regeneration. 



In the Bpinal cord the nerve fibers carrying one kind of Bensation 

 are grouped together, in the Bense thai pain sensations, whether deep or 

 protopathic, run in the Bame column in the cord. Likewise temperature 

 sensations, whether protopathic or epicritic, run together. 



The Peculiarities of Each of the Separate Sensations 



Temperature. The receptors for temperature are arranged in groups, 

 Borne being sensitized for heat, others for cold. These groups of receptors 

 are called heat and cold spots. They can be very easily detected on an 



Fig. 204. Thermoesthesii 

 area of s U i n by means of a pointed hollow vessel, through which water ifl 



made to flow at a temperature a Little below or a little above that of the 

 skin. The instrument is called a thermo-csthesiometer. On a part of the 

 skiii where their are mi heat and cold spots, the thermo-esthesiometer will 



elicit no sensation either of heat or of COld. This is charted on an Outline 



drawing of the part as a neutral spot. At other places it will call forth 



a Bensation of heat, indicating the presence of heat spots, or at othei 



sensation of cold, indicating the presence of cold spots. It will he n< 

 that certain of the spots are much m ictive titan others, and that t 1 



of cold are much the more numerous Bee Pig 205 Both heal and cold 



spots are most fre.pient at the nipples; then, in Order, cine the idlest, the 

 nose, the anterior surface ,,!' the arm. and the abdomen They are 

 marked on the exposed BUrfaCC of the skin, guch .is tin 1 face, and tl 



