16 



PHYSIOLOGY 



CHAP 



These numerous sensitive points for cold, heat, pressure, and 

 pain are not superposed, but are distributed over different parts 

 of the skin. Fig. 3 shows that Blix' points for cold, heat, and 

 pressure are not really spots, but that the sensation spreads round 

 them as though due to a sort of irradiation of the stimulus, so that 

 the sensory points resemble small placques. These sensory points 



are notequidistant norregularly 

 distributed, and consequently 



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 I 



r* w ' 



.Is' 



FIG. 3. Distribution of 

 specific sensory spots on 

 skin of the dorsal surface 

 of the left thumb. (Blix.) 

 Cold spots coloured 

 green, warm spots reil, 

 pressure spots black. 



Fie. 4. Distribution of thermal spots 

 on palmar surface of left forearm. 

 (KiHMnv.) Cold spots marked 

 green, warm spots red. 



there are insensitive areas of skin of varying extension between 

 them. The cold points are much more numerous than the heat 

 points, and the pain points (not shown in Fig. 3) more numerous 

 again than the points for contact or pressure. 



The number of points is much greater according to Goldscheider 

 than to Blix. Kiesow's accurate researches show that the data of 

 the latter are more reliable : he proved that the cold spots of 

 Blix may be analysed into groups of individual cold points. Fig. 4 



FIG. 5. Distribution of cold and tactile spots on dorsal surface of left wrist. (Kiesow.) Cold 

 spots marked green, tactile spots black. The left-hand figure only contains cold spots, the 

 right-hand cold spots and tactile spots in the same area. 



gives the distribution of the thermal points according to Kiesow 

 on the palmar side of the left forearm, Fig. 5 the distribution of 

 cold points and tactile points on the dorsal side of the left wrist. 



Kiesow further found that in regions provided with hairs the 

 cold spots invariably lie near the tactile hair spots but do not 

 coincide with them. He concludes that the vicinity of cold spots 

 to the hair is in relation with the so-called " goose-skin " produced 

 by the contraction of the pilo-motor muscles ; it is presumably 

 due to a reflex arc. 



Sommer continued these studies and found in 1 sq. cm. 

 of adult skin 6-23 cold spots and 0-3 heat spots; on an 



