CUTANEOUS SENSIBILITY 



to tin- I; i ft that appreciation nl' pressure is lust, in e.nta.nenii,- 

 scars. 



Von Frey also suggested with much probability that the pain 

 spots, which arc most abundant in the skin, an- served hy the 

 IVi'i' terminations of tin- superficial nerve-plexus, which supply 

 the epithelium of the Malpighian layer. It is possible that each 

 pain spot corresponds not with a single nerve-ending but rather 

 with a group of nerve-endings, otherwise the pain spots found by 

 v. Krey in certain regions would have to be much more numerous 

 and closer together. The fact that the cornea, which v. Frey 

 found to be destitute of any specific sensibility except pain, is 



A B 



I-'IL. 10. Topography of areas sensitive to cold (A), and to warmth (13), on saw part of the anterior 

 surface of the thiiji. (Goldscheider.) The black areas are highly sensitive to thermal stimuli ; 

 the striated areas moderately so; the dotted areas very slightly ; the spaces left white an- 

 not at all sensitive to such stimuli. 



provided with a nerve-plexus that has free infra-epithelial endings, 

 as described by Cohnheim (1866), supports this conclusion. 

 Similar nerve -endings have also been recently described in 

 epithelium which is not ectodermal in origin, and in the interior 

 of many tissues which increases the probability that they are 

 related to pain sensibility, as this, when very slight, is allied to a 

 sensation of tension or of simple contact, as Nagel(1895), in oppo- 

 sition to v. Frey's view, observed in the cornea. 



It is far less easy to identify the peripheral organs that 

 subserve the sensations of heat and cold. P>y elimination it may 

 be said that Dogiel's corpuscles, Ruffini's papillary endings, and 

 the Golgi-Mazzoni corpuscles are the organs for the sensation of 

 cold, while Pacini's and Rutiini's corpuscles function, at least in 

 the skin, as organs for the sensation nf heat. The fact that the 



