NECROSIS. 



171 



tions ; and so far as the process is completed on that surface, of 

 the living bone which faces the dead, so far is the sequestrum 

 separated." The necrosed portion is very irregular in its outline, 

 and the luxuriant granulations from the 

 living parts shoot into these irregularities, 

 causing a dove-tailing closely resembling 

 actual union. From various specimens 

 in my possession, I find that the dead 

 bone, when of any considerable magni- 

 tude, is removed in numerous portions, 

 that is to say, it becomes broken into 

 several fragments, whicli find their way 

 to the surface through the cloacse time 

 after time. In the annexed illustra- 

 tion five sequestra were found within the 

 capsule. 



The cloacae, or foramina grandia, serv- 

 ing as outlets for the pus and sequestra, 

 present themselves about the middle or 

 lower third of the new bone as oval- 

 shaped openings ; and a remarkable fact 

 has been pointed out by Professor Good- 

 sir, connected with these, namely, that 

 " they are almost invariably opposite to a 

 smooth or unaltered surface of the dead 

 shaft, and that they result from the pus, 

 thrown out from the granulating internal 

 surface of the new shaft, making its way 



. .1 , . 1.1 . i. ^ I'iG. 26.— Section of the 



to the exterior, by the parts not yet bone represented in Fig. 25, 



closed, in consequence of having been showing five sequestra, or 



., , . „ ., 1 1 1 n^ 1 . 1 dead pieces of the original 



opposite portions Ot the old shaft, which bone. a, Capsule; 6 and c, 



had not afforded separate osseous centres." Sequestra. 

 By this, Goodsir means that the smooth surface of that part of 

 the old shaft had not afforded spiculas of bone adherent to the 

 periosteum, when that membrane became separated from the 

 old shaft, to act as centres of ossification ; for he founded the 

 doctrine that the formation of new bone depended not so much 

 on the periosteum, as upon the spiculae of living bone which 

 were attached to it. He says : — " When the entire shaft of a 

 bone is attacked with violent inflammation, there is generally 



