OF CARTILAGE. 29 
the case in the more completely ossified parts; there the cell- 
cavity remains behind, forming a dark indentation in the 
line, which as it advances renders the tissue transparent, and 
leaves the cavity a black spot, from which dark fibres, simi- 
lar to those of the corpuscles of bone, issue in a stellated form. 
Shortly afterwards the fibres disappear, then the corpuscle gra- 
dually diminishes, and at last vanishes also, leaving a pale spot. 
Such an appearance could not be due to an air-bubble in the 
cell-cavity ; for in that case, I think, the course of its exit 
might be followed. It is probably a more compact mass of 
earthy matter, which does not become dissolved so quickly as 
that contained in the substance of the cartilage. After this 
has become impregnated with earthy matter, the cell-cavities are 
also filled, and when so filled they are the osseous corpuscles. 
Similar observations might be instituted on the ossified carti- 
lages of mammalia, in which the identity of osseous and carti- 
lage-corpuscles was rendered more certain by Miescher’s re- 
searches. The next question which presents itself concerns 
the nature of those minute fibres which proceed in a stel- 
lated form from the osseous corpuscles. After the earthy mat- 
ter has been withdrawn the corpuscles may still be seen, though 
rendered very pale by that process; the fibres, however, are 
not at all visible, although a formation corresponding to them 
is certainly present in the cartilaginous substance, and their 
extraordinary minuteness sufficiently explains the invisibility. 
The same formation might also exist before ossification, but 
be invisible from the like cause. As these fibres and the 
cell-cavities become filled with earthy matter simultaneously, 
and at a later period than the cartilaginous substance, and 
since they contain the earthy salts in a more compact and 
less easily soluble mass, it is probable that they are hollow 
tubes, that is, canaliculi which proceed from the cell-cavities, 
spreading out into the cartilagmous substance. According, 
therefore, to the view which we take respecting the cartilage- 
corpuscles, according as we consider them to be the cavities of 
cells, the walls of which have become thickened and blended, not 
only with one another but with the intercellular substance, so 
as to form the cartilaginous substance; or as we take them 
for the entire cells, and the intermediate substance of the 
cell-cavities as only intercellular substance, so must these tubes 
