ITS STRUCTURE AND FUNCTIONS. 263 



As we continue to look at the still deeper layers of the skin, 

 we find fat-cells and muscular tissue in abundance. The contrac- 

 tion of the latter is often demonstrated to us, in every-day life, by 

 the condition known as goose-skin, when the surface of the body 

 becomes chilled. 



Below this fatty layer the skin becomes much less dense, the 

 fibres are further apart, and fat is sometimes enormously deposited. 

 This is called the subcutaneous layer. It is at this point that the 

 skin separates from the muscles below, as in skinning an animal. 



Time does not permit me to speak of various modifications of 

 the skin, such as the hair and nails. Neither can I discuss the 

 curious furrows and ridges on the fingers, which have so absolutely 

 different an arrangement in different persons, and yet are so perma- 

 nent all through life, that Mr. Francis Galton, F.R.S., has suggested 

 a system for recognising old offenders in crime by keeping the wax 

 impression of every criminal's finger-prints for reference in future 

 offences. 



But I must turn for the brief remainder of my lecture to the 

 Physiological functions of the skin, which, I hope, may prove of 

 even greater interest than its structure. 



We may divide them under six heads : — 



I. — Protective. 2. — To prevent the rapid loss of heat or 

 absorption of poisonous materials. 3. — To regulate the body 

 temperature. 4. — To secrete sweat. 5. — The special organ of 

 touch. 6. — Absorption. 



The first function is self-evident and need not detain us. 



The second is of more importance, especially to those who 

 have medical work to perform. Thus, we know that in severe 

 burns or scalds the gravity of the injury depends more on the 

 extent of surface over which the skin is destroyed than upon the 

 depth of the burn. 



The third function is of especial importance to all of us. The 

 human body in health maintains a constant temperature in spite 

 of the changes around it. Thus, if we journey to the frigid Ice- 

 land or to tropica: Africa ; if we drive over the moors in a biting 

 nor'-wester, or recline on a slab in the hot-room of a Turkish bath, 

 a thermometer placed in the mouth would register about 98*6° F. 

 This temperature may be increased or diminished in disease, but 



