508 GREASE. 



character of a specific disease, the assertion must be left 

 undecided. The secretion of the sebaceous glands varies 

 according to the necessities of the part within which they 

 are situated. It cannot be denied, therefore, as probable, 

 that their diseases may exhibit corresponding peculiarities, 

 which we find to be the case in grease. Mr. Percivall 

 notices in this disease its simple form, its ulcerative, and its 

 grapy form. In the simple form there is merely swelling of 

 the skin of the hind legs, which becomes hot, inflamed, and 

 tumefied ; greasy in appearance, moist with exudation, and 

 offensive to smell. It soon assumes the ulcerative cha- 

 racter, and cracks, raw, deep, and excessively tender, mark 

 the next stage of the affection. Unless the further progress 

 of the disease can be arrested, these wide and deep ulcerated 

 cracks throw up loathsome excrescences called grapes: 

 renewed fungoid deposits continue to be added, and the 

 heels become enormously swollen. 



The inflammation productive of grease appears to origi- 

 nate in debility, general or local. It originates in general 

 debility, when the system at large is weakened by long-con- 

 tinued disease ; or from want of proper nutriment ; or from 

 long-continued exertion : in which cases these parts being 

 farther removed from the source of circulation, which itself 

 labours under additional languor, they are thought to suffer 

 proportionally in a greater degree than those nearer to 

 the action of the heart ; hence it is said accumulations 

 take place, which, if not removed, terminate in an inflamma- 

 tion, and in an increase of the secretions peculiar to the leg. 

 This species of general debility appears in spring and 

 autumn, from the efforts nature employs to generate a new 

 clothing of hair. 



Grease may be said to have local weakness for a cause. 

 As fluids press, not in proportion to their diameter, but to 

 the height of their column, the venous blood must find some 

 difficulty to its ascent. Debility is therefore more felt in 

 the distended vessels remote from the influence of the 

 heart, under which circumstance the effects productive of 

 grease necessarily ensue. 



Over-feeding is one of the causes of grease ; and if to this 

 plethoric state the want of exercise be added, the legs will 

 be the parts most hkely to suffer. An inflammatory re- 



