THE SKttf 



235 



part from | to -g-J-g- inch (0.04-0.08 mm.) in diameter. 

 The sense of touch may be one of mere pressure, or when 

 excessive may be that of pain. Naturally, 

 those parts of the body are most sensitive 

 where the papillae which contain these 

 nerve endings are most numerous. The 

 tip of the tongue has the most nerve 

 endings to a given area,, and the finger 

 tips are the next most sensitive organs. 

 Nerve endings are farthest apart on the 

 back, and on the back of the neck. 

 Two points one tenth of an inch (2.5 

 mm.) apart can be identified as two if 

 they are on the finger tips. In the middle 

 of the back, however, two points two 

 and a half inches (66 mm.) apart may 

 be felt as one. 



The Skin as a Protecting Organ. The skin is a protection 

 against the entrance of disease germs. The many over- 

 lapping layers of epidermis cells form such a thick mass that 

 bacteria cannot penetrate it and reach the living parts within. 

 If it is broken, however, bacteria can attack it at once. The 

 need of thoroughly cleansing skin wounds is thus manifest. 



Any of the common antiseptic washes or lotions are of some 

 value, but especially those containing formalin (3-10% is very 

 effective), bichloride of mercury (1 part in 1000), or carbolic 

 acid (2 J/2%), are effective, easily used, and inexpensive. If cer- 

 tain treatments cause sharp pain for a few minutes, this is a 

 good indication, for it probably means that the naked tissue is 

 being killed, with the bacteria on it. 



FIG. 118. A TACTILE 



CORPUSCLE FROM 

 THE FINGER 

 (Ruffini) 



THE SKIN AS AN EXCRETING ORGAN 



The skin secretes perspiration at the rate of one to five 

 pints per day. This quantity varies according to the amount 



