Callous Tumour. 287 
tured face. The soft parts were a confused 
mass of disease, | 
The experiments from 7 to 12, shew disease 
of the external membrane with its consequen- 
ces, deficient effusion, denudation of the bone, 
ulceration of the soft parts, &c. &c. In these 
dissections we may observe the universality 
of the attempt to cover the face of the frac- 
ture; even when disease has produced des- 
truction of the external membrane, and death 
of a portion of the outer surface of the bone, 
this capping and smoothing of the asperities 
of the face of the injury is wholly or partially 
effected, a circumstance which proves it to 
have its origin in the membranous lining of the 
canal, for had it been a production of the outer 
covering, the effusion must necessarily have 
partook of the actions, and shared the fate of 
its parent. In sucha condition of the exter- 
nal membrane, the internal does not wholly 
escape uninjured, sound parts are constantly 
affected by the contiguity of disease in parts 
of a similar organization, and hence its effu- 
sion is scanty, lies loose upon»the face of 
the fracture, and if seized brings away its pa- 
rent membrane, leaving the canal of the bone 
denuded. 
When the external membrane is diseased, 
we constantly find a scanty, or a total failure 
