394 DISEASES OF THE SKIN. 



Gangrene of the Skin. 



We may see necrotic withering of the skin from the effects of 

 extremely high or low temperature, or it may be caused by trau- 

 matic influences, by disease-alterations of the mucous membrane 

 or subcutaneous tissue — for instance, in phlegmoue, acne, and in 

 some cases from internal causes. Spontaneous gangrene belongs 

 to this latter class. It is developed in some cases, according to 

 Moller, on the cheeks, and corresponds with noma in the human 

 species. The disease is recognized by salivation, poor appetite, 

 fever, and necrosis of the corners of the mouth, which may extend 

 gradually over the entire cheek. 



The treatment is to follow strict antiseptic methods; to apply 

 dressings of iodoform, sulphonal, or boric creolin (1 part of creo- 

 lin to 50 of boric acid), and improve the general condition by 

 means of tonics. 



Acne. 



Under the name of ''acne" we mean an inflammation of the 

 hair-follicles and sebaceous glands resulting in suppuration. This 

 is not produced, however, by follicular acari. The anatomical 

 processes which we recognize in this serious eruptive form have 

 been already mentioned on page 385. 



This condition generally appears on the nose, cheek, side of the 

 face, and external fasciae of the extremities, between the toes, and 

 in some cases over the entire body. 



Etiology. Very little is known of the actual cause of this 

 disease. Local irritations have been thought to be the cause, such 

 as constant pressure of the muzzle, rubbing the affected parts, and 

 in certain cases to some hereditary predisposition in the character 

 of the sebaceous glands. Vegetable irritants have also been said 

 to cause this disease when the skin was in a certain irritable con- 

 dition. It is not infectious. 



Clinical Symptoms and Prognosis. This disease develops 

 very slowly, beginning with redness and loss of the skin and 

 hair. These red spots are painful, irregular, swollen, and extend 

 over the surface the size of a large dollar. They are caused by the 

 formation of a large number of pea-like nodules which are hard 

 and firm. In some cases we find the whole surface of the skin 



