280 Observations upon the 
effusions are thrown out, in consequence of 
which, the one is ina more advanced state of 
organization than the other, a circumstance 
which perpetuates, till near the completion of 
the process, this separate appearance of the 
two effusions, the obliteration of which is one 
of the latest circumstances occurring. 
It is this tumour, in the first instance so 
diffused and yielding as to be distinguished — 
through the integuments with difficulty, but 
becoming progressively more defined as it 
becomes more organized, that has been term- 
ed the callous tumour, and of whose origin so 
many opinions have been formed. 
When the process goes on favourably, no 
changes are found, except that of an increased 
secondary effusion, till the fifth or sixth day, 
when the tumour becomes more firm and so- 
lid, cutting rather like the intervertebrary 
substance than like cartilage, and is found 
more denseasthe knife approaches the exter- 
nal membrane of the bone, to which it ad- 
heres, with an extreme firmness. It is not 
necessary to detail singly these examinations, 
they would extend this paper too far; it is 
only necessary to detail leading appearances. 
When the process of reunion goes on unfa- 
vourably, whether the causes are constitu- 
tional or local, their effect is such as to dimi- 
