1(5 ABSORPTION, ULCEKATION, &c. 



In this process, the veins and absorbents act on the osseous 

 texture of the walls of the haversian canals in no otherwise than 

 in the natural state of the part. They are mediate, not imme- 

 diate instruments of absorption. It is the cells of the newly 

 formed cellular mass, contained in the haversian canals, which 

 are the immediate cause of the removal of the bone, either by 

 taking it up as nourishment, and substituting themselves in its 

 stead ; the bone being prepared for this absorption in a manner 

 analogous to that which occurs in the digestion of food previously 

 to absorption of it by the cells of the gut :* or by the active for- 

 mation of the cells of the new substance monopolizing the re- 

 sources of the part, and so inducing the disappearance of the 

 osseous texture by the natural channels of the returning cir- 

 culation. 



The process by which a slough in the soft parts is separated 

 from the living textures, is similar to that which occurs in bone. 



In this view of ulceration, there is substituted for the hypo- 

 thetical active, or aggressive power of absorption ascribed to the 

 veins and the lymphatics, a power which is known to exist in the 

 organic cell during the progress of its growth ; and the ultimate 

 removal of the matter from the scene of action is ascribed, partly 

 to the formation of discharge, partly to the yet unexplained, but 

 at the same time undoubted, and in all probability passive agency 

 of the returning circulation. 



J. G. 



* " Hence, the digestive process, instead of being confined to the stomach and duodenum, 

 is actually carried on without intermission, in all pails of a living animal body." Prmifa 

 Bridyewater Treatise, page 534. 



