TOUCH, ETC. 23 



who habitually expose the hands, or even the feet, to cold, ren- 

 der these parts quite insensible to temperature ; and the same 

 is true for those who often expose the hands, face, etc., to heat. 



The variations in the sensibility of different parts of the 

 surface to temperature depend, as we have just indicated, 

 to a great extent, upon habit, exposure, etc., but also upon 

 special properties of the parts themselves. The differences, 

 however, are not so marked as to be of any great importance, 

 and the experiments made upon this point are simply curious. 

 It is remarkable, however, to note the exquisite sensibility to 

 variations in temperature sometimes presented by those who 

 are deprived of other senses. The example is quoted by 

 Dunglison, of Dr. Saunderson, formerly Professor of Mathe- 

 matics at Cambridge, England, who, " when some of his pu- 

 pils were engaged in taking the altitude of the sun, could 

 tell, by the slight modification in the temperature of the air, 

 when very light clouds were passing over the sun's disk." 1 



The experiments of Weber show conclusively that the 

 skin is the main organ for the appreciation of temperature, if 

 we except the mouth, palate, vagina, and rectum, by which 

 the difference between warm and cold substances is readily dis- 

 tinguished. In several instances in which large portions of 

 the skin were destroyed by burns and other injuries, experi- 

 ments have been made by applying spatulas of different tem- 

 peratures. At one time a spatula plunged in water at from 

 48 to 55 Fahr. was applied to a denuded surface, and again, 

 a spatula at from 113 to 122 Fahr. When the patient was 

 requested to tell which was the warmer, the answers were as 

 frequently incorrect as they were correct ; but the discrimina- 

 tion was easy and certain when the applications were made 

 to the surrounding healthy skin. When applications at a 

 higher temperature were made to the denuded part, the pa- 

 tient suffered only pain. 2 



1 DUNGLISON, Human Physiology, Philadelphia, 1856, vol. i., p. 697. 

 8 WEBER, Der Tastsinn und das Gemeingefuhl, in WAGNER, Handworterbuch 

 der Physiologic, Braunschweig, 1846, Bd. iii., zweite Abtheilung, S. 513. 



