BY MOLECULAR COALESCENCE. 119 
bone; and all those changes of structure Which have been 
so elaborately described in the parts of cartilage, near to 
which the process of ossification is going on, are only such 
as are consequent on the removal of cartilage, and not 
necessary for the production of bone, as is shown by the 
fact that bone is formed just as well without cartilage as 
with it. As the process of ossification advances, the 
circular areas enclosed by the osseous rings become gradu- 
ally but only partially filled up. (Fig. 8 is an accurate 
representation of this stage of 
the ossifymg process from the Hig: Be 
same animal. ‘The part here re- Sud 
presented had not been in any Tey es 
way mutilated. It was in glyce- Sy z 
S 
rine. It shows- how the canali- Me S 
culi are merely the result of A oe 
spaces left between the coalescing wil 
granules, which converge towards, 
and terminate in, a central un- 
ossified part, called a lacuna, or what physiologists and 
histologists consider to bea “ bone-cell.”) The other form 
of the ossifying process, that in which the bone in progress 
of development is connected with fully formed bone, 
resembles the one just described, in all pomts but one, 
which consists in the osseous granules being deposited in 
loops or arches, with their extremities connected with the 
most recently formed bone. The spaces enclosed by these 
osseous arches are at first large, but they become gradu- 
ally but imperfectly filled up, exactly in the same manner 
as the circular areas in the other form, and canaliculi and 
lacune remain. ‘This form can be seen, also, without 
mutilating the parts, in the young frog, as well as in the 
tendon of the bird, as before observed. I have seen it 
