468 Proceedings of the Royal Physical Society. 



lining layer of vascular embryonic tissue, similar to that 

 already mentioned (Fig. 1 c), and at the deepest part of this 

 granulation tissue layer altered muscular fibres (Fig. 1 d). 

 The irregular outline of both sequestrum and cavity are also 

 observed in both fowl and fish. 



In the fowl gradual absorption of the sequestrum takes 

 place, when once it becomes completely detached from the 

 surrounding tissues, but this may take several months, and, 

 whilst this is going on, "the fragments have become very 

 friable, they are readily broken down, and form in part a 

 kind of caseous magma." ..." The older the sequestrum, 

 the greater is the tendency of the blocks to lose their striation." 

 Following this there is disintegration, fatty degeneration, and 

 gradual absorption by the granulating surface. 



Cornil speaks of the cyst wall surrounding the sequestrum 

 as consisting essentially of granulation tissue, and the older 

 forms of organising tissue. He says there are three layers : — 



1. "An internal layer, continuous with the debris of the 

 sequestrum, and in which one finds giant cells of special 

 forms." (These were not present in the specimen under our 

 notice.) 



2. "A middle layer composed of large fusiform or branch- 

 ing cells. 



3. "An external layer formed of embryonic connective 

 tissue, which is continuous with the pectoral muscle. This 

 deep layer is traversed by numerous blood vessels." 



By the aid of the granulation tissue with its actively 

 digesting cells, the sequestrum is gradually absorbed, after 

 which cicatrisation takes place. 



I have quoted much more freely from M. Cornil's paper 

 than I am perhaps justified in doing, but the singular 

 resemblance between the two processes must be my excuse. 



It is quite possible that in the specimen before us we 

 have no micro-organismal origin, but it is certainly more 

 than probable that micro-organisms, though not to be found 

 at this late stage of sequestrum formation, have still been 

 present at some earlier period. A reference to Figs. 1 

 and 2, will show at once that the processes have ended in 

 much the same wav. The altered muscular fibres in the 



