TACTILE SENSE. 



733 



fingers of a blindfolded person there results a sensation of two balls 

 being present instead of one. 



There are spots of temperature which have been worked out by 

 Goldscheider. They are found to be arranged in a linear manner 

 and generally radiate from certain points of the skin, usually the 

 hair-roots. The chain of "cold-spots" does not coincide with those 

 of "warmth-spots." The sensation of cold occurs at once; that of 

 heat .develops gradually. As a rule, the cold-spots are more abund- 

 ant over the entire body surface. The hot-spots may be quite absent. 

 The minimal distance on the forehead for cold-spots is 0.8 milli- 

 meters while for warmth-spots it is 5 millimeters. 



If I * I : : ' 



"".' . .. 



* -. llllll Illi 



Fig. 300. Topography of Sensibility to Cold and Heat in the same 

 Region of the Anterior Surface of the Thigh. (GOLDSCHEIDER, HEDON.) 



a, Cold spots. 6, Hot spots. Most sensitive spots in black; moderately sensi- 

 tive spots are hatched; spot feebly sensitive, in points; spots which are white 

 are not sensitive. 



Protection of the Organs of Touch. 



The means are the cutaneous oil and the horny appendages. The 

 cutaneous oil is the product of the sebaceous glands of the skin. 

 They are found in every area of the skin, but are less numerous than 

 the sudorific glands except in the palms of the hands and soles of 

 the feet. They may be large, as in the nose; these usually have 

 fine, downy hairs near their mouths. 



The sebaceous glands are situated more superficially than the 

 sweat-glands. They are white granules annexed to the hair-follicle, 



