128 HEALTH AND DISEASE 



the tongue proved to be most sensitive, as it was capable of appreciating 

 the two points of the compass when the distance between them was only 

 half a line. On the palmar surface of the third finger it was one line; 

 on the red surface of the lips, two lines; on the tip of the nose, three lines; 

 on the skin of the cheek, five lines; on the mucous membrane of the gums, 

 nine lines; on the skin over the sternum or breast, twenty lines; on the 

 skin over the spine of the back, thirty lines. Investigators who followed 

 up Prof. AVebber's experiments found, as might have been expected, a con- 

 siderable amount of individual variation, some persons being able to appre- 

 ciate the points at a half, even at a third, of the distance required by others. 



The sensibility in the skin to impressions of weight has also been tested 

 by different investigators, and it was found that, on the face, the pressure 

 of a portioii of elder pith presenting a surface of nearly -§- inch square, 

 and weighing only -^ grain, could be distinguished, whilst the tips of the 

 fingers required a weight of | grain and more, the toes as much as 8 grains, 

 before any sensation of pressure was felt. In regard to temperature, it was 

 found that the left hand was more sensitive than the right, although the 

 right has the sense of touch most acutely developed. The curious fact was 

 also noticed, that a weaker impression made on a large surface conveys the 

 idea that it is more powerful than a stronger impression on a small surface; 

 thus, if the forefinger of one hand be immersed in water at a temperature 

 of 104°, and the whole of the other at 102°, the cooler water will be felt to 

 be the warmer; further, it is a known fact that water in which a finger can 

 be held will scald the whole hand that is plunged into it. From these 

 experiments it may be gathered that the sense of touch does not afford 

 much assistance in obtaining accurate information as to the temperature 

 of bodies. Indeed, it is well known that the temperature of the surface of 

 the person who makes the experiment has its effect. For instance, a cold 

 hand will appreciate a very slight rise of temperature in anything it 

 touches, whereas it would distinguish little or no change in touching a 

 body which was nearly the same temperature as itself. 



Skin as an Organ of Absorption.— Absorption through the surface 

 of the integument has always been a matter of dispute. At one time a 

 system of administration of medicine was in fashion, under the name of 

 the endermic system, and was certainly based on a decided belief in the 

 absorbing powers of the skin, but the system itself implied the use of con- 

 siderable friction with mercurial preparations mixed with fatty materials in 

 the form of ointment, the fatty matter being the more readily absorbed if 

 it were rancid. It is stated that De Collin produced absorption in an 

 experiment to which he had recourse, which consisted in causing water 

 impregnated with cyanide of potassium to fall in drops on a horse's back 



