BAUR, ON OSSIFICATION OF CARTILAGE. 27 
The processes, which have in part been long well known, 
which are here seen to precede the ossification, are as fol- 
lows: The cartilage-cells,.which were previously uniformly 
dispersed, assume a definite order, corresponding to the sub- 
sequent bony structure; in the cartilages of the long bones 
they dispose themselves in rows, which, in a transverse sec- 
tion, appear like rounded groups. At the same time the 
individual cells increase in size, their contents, at first opaque 
and granular, become transparent, and exhibit a large vesi- 
cular nucleated nucleus. This enlargement of the cartilage- 
cells is effected at the expense of the matrix, which is even- 
tually so much diminished in proportionate bulk, that the 
separate rows of cells are separated only by a thin layer of . 
intercellular substance, whilst the cells in each row are 
themselves in absolute contact. A deposition of earthy 
elements, in the form of an opaque, coarse- or fine-grained 
material, now takes place on the walls of these cartilaginous 
cavities or canals. This deposit of earthy matter “forms 
apparently the distinction between cartilage and bone, but 
the microscopical characters of bone are still wanting—the 
bone-corpuscles, that is to say, and a homogeneous matrix. 
The cartilage-cells as yet lie unchanged in the cartilaginous 
capsules incrusted with calcareous matter, and whose opacity, 
even, renders the tracing of their further metamorphosis 
difficult. This, however, in the next place, consists in the 
circumstance that each cartilage-cell becomes the seat of an 
endogenous cell-formation ; for in place of a single vesicular 
nucleus, which may already be regarded as a secondary cell, 
several ‘vesicles of the same kind make their appearance, 
which fill the parent-cell, and after its disappearance become 
free. It is this brood of cells thus corresponding to the 
nucleus of the cartilage-cells, which constitute the contents 
of the calcified cartilaginous cavities, and become the start- 
ing point of all the subsequent changes. The fact, that in the 
ossification of cartilage an endogenous cell-formation takes 
place in the cartilage-cells—a process which is to be essen- 
tially distinguished from the multiplication of cartilage-cells 
by division, ‘such as is noticed in the growth of the cartilage 
before the commencement of ossification—has hitherto been 
adduced by all observers only in connection with the forma- 
tion of the medullary constituents of the bone, its import- 
ance as regards the origin of the bone itself not having been 
recognised. For whilst, in fact, part of this new generation 
of cells is transformed into blood-vessels, fat-cells, or indif- 
ferent medulla-cells, the peripheral cells, in apposition with 
the calcified cartilaginous capsules, are always surrounded 
