Diseases of the Skiic. 455 



I2th. Callositas : Callosity. Abnormal thickening of the 

 epidermis, as a pliysiological protective cell growth. Examples: 

 pads on the knees of camels, cows and even horses from kneel- 

 ing on a hard, uneven surface. 



13th. Sitfasts : Necrotic Callosities. Coml)inatiou of dried 

 up exudate of horny consistenc}', and a thickened, fibroid and 

 partiall}^ necrotic portion of the subjacent derma with little or 

 no disposition to spontaneous detachment. 



14th. Cornu Cutaneum : Keracele.: Horny Growth. Ab- 

 normal horny growtli from keratogenous tissue, or from the 

 derma in its vicinity or at some other point of the skin. 



15th. Erosions : Abrasions. Lesions of the cuticle expos- 

 ing the true .skin, and the result of itching, scratching, friction, 

 biting or other mechanical or thermic injury. 



16. Rimae : Cracks : Chaps. These are linear breaches 

 often confined to the epidermis in the bends of joints, under 

 congestion and suppression of sebaceous secretion, in elephanti- 

 asis, dropsy, petechial fever, etc. Unless they have ulcerated 

 the}' may heal without cicatrix. 



17th. Crevasses : Fissures. These are chaps, which ex- 

 tend into the derma, giving rise to destruction of tissue and leav- 

 ing a cicatrix on healing. Examples are found in the hollow of 

 the pastern, behind the knee (Mallenders), in front of the hock 

 (Sallanders), in the swellings of petechial fever, malignant 

 catarrh, stocked legs, grease, etc. 



i8th. Ulcus : Ulcer. A sore that extends by the continual 

 molecular breaking down of the forming granulations and of the 

 adjacent and subjacent diseased tissue. 



19th. Excrescences: Hyperplasiae : Phymata : Derma- 

 tomata. These may include over luxuriant granulations which 

 rise above the level of the skin and become organized into pro- 

 jecting fibro-cellular, raw or scabby masses : tumors of all kinds 

 — warty, papillomatous, horny, epidermic, cancerous, .sarcoma- 

 tous, pigmentary, angeiomatous, tuberculosis, etc. 



20th. Cicatrices : Scars. These are puckered, raised or 

 sometimes depressed, lines or areas of conden.sed connective tis- 

 sue with a covering of epidermis, taking the place of the normal 

 dermis and epidermis and their appendages, which have been 

 destroyed. They result from traumatic, ulcerous, or atrophic 

 destruction of the skin. 



