Intereellular Substance of Cartilage, 
103 
spaces^ and there must have heen at least ten distinct nuclei 
or masses of living germinal matter. There is a nucleus or 
mass of living germinal matter in every single case in, or 
about the centre of the ring of calcareous particles. The 
calcareous matter is always first deposited around and at a 
distance from the germinal matter^ in fact^ in the very part 
of the formed material which was first produced^ and is^ there- 
fore^ at the time of ossification-, the oldest. I pass round a 
specimen where one or more masses of germinal matter may 
be seen with the ring of calcareous particles around them. 
(Prep. 6, PL IX^ fig. 14.) Now, as long as these masses 
of germinal matter live in the normal condition^ so long the 
deposition of calcareous matter proceeds in a direction from 
without inwards^ or, as the fact would be generally stated, 
the lacuna becomes smaller as the tissue grows older. In 
every lacuna, even of fully formed living bone, a nucleus or 
mass of germinal matter exists. (Figs. 11, 12, 13.) If the 
lacuna is a real space, filled only with air or fluid, the bone 
is dead, and the lacuna could not become smaller. 
JBone, therefore, cannot be formed independently of living 
or germinal matter. 
The formation of the matrioc of bone depends upon the 
changes taking place in germinal matter, and these changes 
must, at least, at present be referred to a force, power, or 
influence, the nature of which we do not understand — vital 
pov^er. The matrix having been formed, the precipitation of 
calcareous matter takes place. This is merely due to a 
chemical change, the reaction of the oldest part of the matrix 
becoming alkaline ; but it would seem that the currents flow, 
ing to and from the gradually diminishing mass of germinal 
matter determine the position in which the precipitation 
takes place, and so long as these masses are alive, the con- 
version of the outer part of each into matrix, and the deposi- 
tion of calcareous matter in the matrix already formed, goes 
on in one definite direction from without inwards ; so that in 
all cases the matrix exists for some time before it becomes 
impregnated with calcareous matter, the precipitation com- 
mencing in the oldest part of the matrix, and proceeding in 
the same direction as the formation of matrix itself — that is, 
from without inwards. When this mass of living matter 
dies these changes cease, and the corresponding portion of 
bone-tissue is dead. If, on the other hand, one of these 
nuclei or masses of living matter be too freely supplied with 
pabulum, it rapidly increases, divides, and subdivides. The 
tissue already formed around it becomes softened, disin- 
tegrated, and appropriated, and a soft mass composed of 
VOL. XI. i 
