206 



THE SKIN 



by disease-producing germs. This protection would be 

 more complete, were it not for the openings of the sweat 

 glands and hair roots, which occasionally afford them 

 entrance and permit their development in the form 

 of small abscesses, pimples, or large abscesses, boils. 



Skin 



Hair follicle 



Fat-laden 

 connective tissue 

 Blood vessel 



White corpuscles 

 bacteria (pus) 



Fat 



PIG. 113. Section of the skin and underlying tissue of the back, showing the 

 spread of pus in a carbuncle. (After Warren.) 



These ordinarily remain in the skin and do not pene- 

 trate into the tissues below. They tend to work out- 

 ward, destroying the skin as they go, until finally they 

 break through the surface. Sometimes, however, when 

 the invading microbes are of a very active form or when 

 they develop in very tough skin, such as that on the back, 

 they tend to work inward and form large spreading ab- 

 scesses called carbuncles. When the skin is broken, 

 microbes are able to find their way into the lymph 

 spaces, where they have a chance for development, pro- 

 vided that they can resist the attacks of the white blood 

 corpuscles. 



