There is cellular texture in the cartilages, though the want of
interstices between their fibres, renders it very difficult to
distinguish it in a natural state; in fact the development of fleshy
granulations in wounds in which they are concerned, ebullition which,
after having removed the gelatine, leaves a membranous and cellular
residue, prove abundantly the existence of this texture, which we see
besides in a very evident manner in some morbid states, in which the
gelatine less copiously deposited in the cartilages, ceases to give
them their usual hardness and leaves there a soft texture, often like
sponge.
We do not discover any blood vessels in the cartilages. The exhalant
system circulates only white fluids in them; but as this system is
continuous with the arteries of the neighbouring parts, when the
organic sensibility is raised in it by morbid irritations, and it thus
becomes in relation with the red globules of the blood, these globules
easily pass into it, and hence the redness the cartilages then have, as
we see in their inflammation, in wounds of them, &c. It is this same
phenomenon that we observe upon an inflamed conjunctiva, &c. When the
irritating cause has ceased, the sensibility resumes its natural type,
the red globules then become heterogeneous to the cartilage, which
again becomes white.
We are ignorant of the nature of the white fluids which usually
circulate in the vascular system of the cartilages. These fluids very
easily become the vehicle of the bile, or at least of its colouring
matter, which is spread through the animal economy in jaundice. We
observe almost uniformly, that in this disease the cartilages are of
a yellow colour, like all the other parts; the colour is more evident
on their surface than in their texture, though it exists there. By
opening a moveable articulation, the bilious appearance is commonly
found as great there as upon the skin. Besides, all the parts, which
like them, receive but few or no red globules in the ordinary state,
are also found very evidently coloured. The tendons, the conjunctiva,
the internal membrane of the arteries, &c. are examples of this. I have
remarked in two subjects whose thyroid cartilages were ossified in the
middle, that the yellow colour was much brighter in the osseous than
in the cartilaginous portion. I do not know that nerves have ever been
traced in the cartilages.