The properties of texture are very well marked in the medullary organ.
1st. The spina ventosa in which this organ is distended in a very
evident manner with the body of the bone, proves its extensibility. 2d.
The contractility of texture is made apparent by the contraction of
the cells, after the amputation of the middle part of a long bone, a
contraction which prevents the flow of marrow, which without it would
take place on account of the communication of these cells.
It is probable that the insensible organic contractility, which is
then brought into action by the contact of the air upon this membrane
which contracts from its irritation, has an influence also upon this
phenomenon; for this membrane evidently has this kind of contractility,
as well as the corresponding sensibility.
The animal sensibility is developed in it to an extreme degree in
the natural state; the most acute pains are the result of the action
of the saw upon it in amputation, of the introduction of a probe, of
the injection of an irritating fluid into the medullary cavity, or
of any other means which powerfully excite it. I do not speak of the
pains of the bones in spina ventosa, syphilis, &c.; as the membrane is
not then in a natural state, we cannot infer from them what kind of
vital forces it is naturally endowed with. I have observed that the
sensibility is greater, as we approach the centre of the bone with
the probe when pushed into living animals. At the extremity of the
medullary canal this sensibility is small; in the middle, the division
of the bone is very painful. Whence arises this inequality of sensitive
power, this decrease from the centre to the extremities? I know not.
The medullary system evidently does not possess animal contractility
and sensible organic contractility.
It is evident from this view of the vital forces which animate this
system, that the life is much more active in it than in the osseous
system, that its vital phenomena are consequently more rapid, that
they have not that chronic course which characterizes all the diseases
of the bones and that they respond more promptly to the sympathetic
excitements of other organs. I am persuaded that many of the uncertain
pains which we usually refer to the bones in diseases, have their seat
rather in the medullary system, in that of the middle of the long
bones especially; observe in fact that most of these pains are fixed
in the middle of the limbs, and that they are really in the direction
of that system. The medullary system of the extremities of the long
bones, and of the flat and short ones, certainly enjoys much more
vital energy than the osseous texture itself; inflammation is much
more easily developed in it, its effects are more promptly shown. Who
does not know that caries is so much the more rapid, in proportion to
the quantity of the texture of the cells that exists in the bones? It
is not this texture, which by its nature, has an influence upon this
phenomenon; but it is, because the more abundant it is, the more the
medullary system predominates in it; now as this participates in all
its affections, it imprints upon them a rapidity which they have not in
the compact texture in which it does not exist.