SECRETION. 289 



blood, and that checked perspiration is one of the most pow- 

 erful causes of disease and death,(we shall see how important 

 it is to keep the pores of the skin free, by frequent washing 

 and bathing at all seasons of the year^ 



13. When the surface also is chilled by cold, and reaction 

 does not follow, the blood-vessels become contracted all over 

 the skin, and the blood retreats to the inner parts of the 

 body ; the 29 ounces of waste and noxious matter, which 

 ought to be discharged, are kept in the system, and sickness 

 is the consequence. Accordingly, we find that it is a good 

 remedy, in most cases of disease, to excite a perspiration and 

 keep it up for some time. 



14. The uses of transpiration by the skin, are,(not only 

 to carry out of the body the noxious properties of the blood, 

 but also to render the skin soft and pliable, the sense of 

 touch delicate, and also to cool the body when exposed to 

 great heat] 



15. The exhalation from the lungs closely resembles that 

 from the skin. It was once supposed to be formed in the 

 lungs, by the union of hydrogen from the blood, and oxy- 

 gen from the air, thus forming water ; but it is the opinion 

 of most physiologists at present, (that it is either the watery 

 part of the mucus secreted by the mucous coat of the lungs 

 and air passages, or that it is given off directly from the 



16. (The Follicles, are small sacks or bags, found in the 

 skin, and the mucous membranes.) The pores which we see 

 on the skin are only the outlets of these follicles. Their use 

 is to secrete an oily matter to mix with the perspiration, and 

 help to keep the skin soft and moist ; when these outlets are 

 closed, sometimes there appear small black specks on the skin, 

 sometimes called worms, but they are nothing more than 

 hardened mucus. Every hair has a follicle at its root, and 

 the wax which collects in the ears, is secreted by follicles. 



17. The chief agents of secretion in the body, are the 

 glands,: which are bodies of various size, generally of a 



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