This system exists in all the organs; all are in fact composed of an
infinity of capillaries, which cross, unite, separate and unite again,
by communicating in a thousand ways with each other. The vessels of
any considerable size, those among the arteries, in which the blood
circulates by the influence of the heart, and those among the veins,
which correspond to the first, have really no connexion with the
structure of the organs; they wind along their interstices; and are
lodged in the cellular texture that separates their lobes; but the
capillaries alone essentially make part of these organs, they are so
combined with them; that they truly enter into the composition of
their texture. It is in this view, that we may with truth consider the
animal body as an assemblage of vessels.
From this first view, it is evident that the extent of the general
capillary system is immense, that it embraces all the smallest
divisions of our bodies, so that we can hardly conceive of any organic
particles united without capillaries. It follows hence, that this
system is not only an intermediate one between the arteries and the
veins. It is from it, that all the exhalants, all the excretories,
&c. go. It furnishes all the vessels that carry nutritive matter to
our organs; we ought to describe it then as existing in parts where
arteries do not penetrate, as well as in those where they do.