EXOSTOSIS. 465 
To avoid the always serious operation of sequestrotomy, chemical agents 
have been recommended to obtain the dissolution of the necrosed tissue. 
Some twenty years ago, Pollock recommended in man, the use of sulphuric 
acid mixed with its weight of water. Painted over with this solution, the 
sequestrum becomes soft, brittle, it is partly dissolved and the rest is elim- 
inated by suppuration. Marcacci recommended perchloride of iron to 
activate the delimitation. For him, this agent irritated the healthy living 
structure and promoted the formation of numerous capillary vessels which 
soon isolated the necrosed from the living parts. Morris more recently has 
advanced another process. The fistulas being enlarged with the knife, he 
injects a solution of muriatic acid (2 or 3 p. 100), which dissolves thé 
calcareous elements of the necrosed bones without acting on the living ones. 
A chlorhydropepsic solution thus' used and composed of: muriatic acid, 
16 drops; pepsine, 2 grammes; distilled water, 120 grammes, digests the 
caseous and fatty detritus remaining of the decalcified bone. In using 
alternately both solutions, the sequestrum is rapidly destroyed and re- 
covery obtained. 
In preference to these chemical treatments, the more rapid and more 
certain operating methods are generally in use. 
During all the time of the treatment, the patient should receive gener- 
ous diet, stimulants and tonics. The progress of the disease should be 
carefully watched, and the complications likely to occur avoided. 
VII. 
EXOSTOSIS. 
Result of a productive osteo-periostitis, exostosis are particularly fre- 
quent in the extremities, where many receive special names. In a gen- 
eral way, the name of exostosis is given to well defined bony tumors ; that 
of periostosis to diffused neoformation; that of hyperostosis to the in- 
crease in size of a bone in its dimensions. In the point of view of 
their structure they are divided into: rst, eburnated exostosis, contain- 
ing no blood vessels; 2nd, compact exostosis, formed of dense tissue ; 
3d, spongy exostosis, made of areolar tissue. In relation to their seat, 
they are epiphysar, developed on the surface of bones; parenchymatous, 
formed in the thickness of the bone; eostosis, occupying the medullary 
canal. 
For a long time, observers have noticed that exostosis developed spe- 
cially on a level with the surface of insertion of the principal ligaments ; 
osselets, on the points of attachment of lateral or interosseous ligaments ; 
-splints, on the line of interosseous fibres ; vimgdones of the pasterns, near 
