CUTANEOUS SENSIBILITY 



29 



region in which sensibility to warmth is more developed than 

 that to cold. This holds good both for the covered and for the 

 uncovered regions. Where the sensibility to heat is highly 

 developed, that to cold still preponderates, both in intensity and in 

 extent. There are as we have said regions in which sensibility 

 to cold is more or less acute while sensibility to warmth is very 

 low or entirely absent. 



The varying thermal sensibility in different cutaneous areas 

 depends not only on the greater or less abundance of cutaneous 

 nerves, but also on the varying thickness of epidermis that covers 

 the nerve-endings, and also perhaps on the depth at which the 

 nerve-endings themselves are situated. 



Previous to the discovery of the duality of thermal sensation 



FIG. 20. Topography of sensibility to cold (A), and to heat (B), in same part of palm of left hand. 

 (Goldscheider.) Explanation in previous figure. 



Weber and Nothnagel attempted to map out thermal sensibility 

 by exploring certain regions of the skin with flasks of oil, or with 

 the rounded ends of large keys previously cooled or heated. After 

 the discovery of heat and cold spots, Goldscheider (1887) extended 

 the research by using metal cylinders, at a temperature of 15 

 for cold and 45-49 for heat. More recently Veress (1902) has 

 again investigated sensibility to heat on himself by means of his 

 thermo-aesthesiometer (Fig. 1, p. 14). Here we can only cite the 

 most conclusive of his general results : 



() Sensibility to heat is not equal in the two halves of the 

 body. On an average it is rather greater on the left than on the 

 right. 



(6) The most mesial parts of the trunk are, generally speaking, 

 less sensitive to heat than the lateral regions. 



(c) The trunk is, generally speaking, more sensitive to heat 

 than the extremities. 



