GENERAL DISEASES OB THE BONES. 297 



affected portion of the bone is tender to pressure or percussion, 

 and is the seat of sweUing at first soft and yielding, but later 

 hard and resistant. In the severer forms the bone itself is 

 softened, extensive exudation of lymph takes place around it, 

 and the investing soft structures become the seat of violent in- 

 flammation and swelling; lameness is then extreme. In the 

 slighter and chronic cases there is no disturbance of the general 

 health, but in the more acute and severe, intense and even fatal 

 irritative fever may come on. 



When suppuration takes place in the interior of a bone the 

 matter may remain imprisoned indefinitely, the spot being 

 marked by a general increase of the bone, and lameness persists. 

 If suppuration takes place between the bone and its fibrous 

 covering the danger is even greater, for the matter is liable 

 to separate the bone and membrane, producing further in- 

 flammation or ulceration, or even death of the bone — the supply 

 of blood being cut off. The superficial abscess is to be detected 

 by its fluctuation beneath the fingers, as in abscess of soft parts 



Ulceration may result from presence of matter, etc., or from 

 exposure to the air. If without external opening, it is not easily 

 recognized, but there is lameness and tenderness, with little 

 alteration of the surface of the bone, or the presence of slight 

 bony deposits alternating, it may be, with soft open spaces. If 

 the ulcerated bone is open to the air, it is found to be softened 

 in texture, breaking down readily under the pressure of a 

 probe, and in the centre of the ulcerous cavity rounded bony 

 deposits are felt, as evidence of an effort at repair. The dis- 

 charge is then ichorous, and abounds in gritty particles and 

 earthy salts. If this discharge has commenced to decompose 

 it smells badly. 



Death of bone is always associated with an open sore dis- 

 charging a very fcetid ichorous fluid, with gritty particles and 

 the power of rapidly blackening silver. If probed the hard 

 bone is felt without any fibrous covering, and if seen this is 



