ANATOMICAL. 217 



stance. There are no blood-vessels in the outer skin ; its 

 only object is to protect the inner skin with all its delicate 

 nerves and vessels ; and here is a very striking instance 

 of design which this epidermis has " acquired " (?), for it 

 has the power of growing faster than the other skin, 

 where most it is wanted ; that is, upon those parts which 

 are most used, as if what we call " nature " foresaw the 

 necessity, and made provision for it. 



It is on such a slide that we see the distribution of the 

 sweat-ducts, which have so much to do with health and 

 disease. You behold them running from coiled-up bundles 

 beneath both skins, embedded in deeper layers. These 

 sweat-glands, you will perceive, consist of a tube, the 

 opening of which is on the outside of the outer skin, and 

 on one square inch of the palm of the hand there are as 

 many as 3528 ; * they run up from their bundles into the 

 epidermis in a corkscrew form, starting from a bed sup- 

 plied with blood-vessels which are appointed to nourish 

 them. Their number is astonishing ; 2800 are said to 

 be found in every square inch of the skin, and as there 

 are 2500 square inches on an average-sized human body, 

 it will follow that their number over the whole body will 

 amount at least to seven millions. You will see that 

 these glands take a wave-like direction from their base 

 to their summit. When straightened they will measure 

 a quarter of an inch in length, so if all their tubing were 

 placed end to end it would amount to 1,750,000 inches, 

 or 145,833 feet, or 48,611 yards, which is upwards of 

 27 miles.f And the health and comfort of a life- 

 time greatly depends upon the correct performance of 

 all this system of main drainage, without any power of 

 ours to alter it, though, on the whole, we may help or 

 hinder it. 



* Erasmus Wilson. f Dr. Lawson. 



