As we advance in age the fibrous system becomes stronger and more
compact; it remains stationary in the adult age, though the alternate
absorption and exhalation of nutritive substances constantly continue.
These two functions can scarcely be seen in the ordinary state; but the
first is very apparent when from a contusion or any internal cause, the
periosteum, the fibrous capsules, the ligaments, &c. swell. The second
in its turn predominates, when the swelling subsides and resolution
takes place.
In old persons, the fibrous system becomes more and more compact and
contracted; it yields more slowly to maceration and putrefaction. The
teeth of animals that feed upon it, tear it with more difficulty; the
gastric juices act upon it less easily. Spallanzani has observed, that
the tendons and aponeuroses of old animals were much more indigestible
than those of young ones. With age, the force of the fibrous texture
increases; but its softness diminishes; hence the difficulty of the
motions, from its stiffness. The ligaments and the fibrous capsules do
not allow the articular surfaces to separate easily from each other;
the tendons bend with difficulty; when we pass externally on places
where they are directly under the integuments, we perceive that they
are hard, not supple, &c. It requires a long time to soften them by
ebullition. The whole fibrous system becomes yellow. We should say that
it approached then that state in which it is compact, semi-transparent
and has the horny hardening to which desiccation reduces it; so that if
we could suppose this system going through quicker than the others the
different periods of its decrease, all the motions would cease from the
rigidity of the ligaments, tendons and aponeuroses, though the energy
of contraction might still subsist in the muscles.