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46 ESOTERIC ANTHROPOLOGY.
are two. They are of nearly the same structure in
birds and mammalia as in man, a spongy mass, made
up of air-tubes, air-cells, and blood-vessels, all bound to
gether by cellular tissue.
Fig. 17.
BRONCHIAL TUBE AND AIR-VESICLES.
Fig. 17 represents the bronchial tube and its division into air-cells, as
much magnified. 1. A bronchial tube. 2, 2, 2. Air-cells, or vesicles.
8. A bronchial tube and vesicles laid open.
The windpipe consists of the larynx, or organ of the
voice, in the upper and most prominent part of the
throat, which opens from the pharynx, just back of the
root of the tongue ; the trachea, a tube three or four
inches long, made up of cylindrical rings and strong
membrane, and its branches, or bronchia, which fork
off to the right and left lung, and afterward divide like
the branches of a tree, and are covered with masses of
a.r-cells, into which they open, and which are clustered
upon them like leaves on a tree, or more like grapes
on a stem; the cells on each twig opening into each
other. There are many millions of these cells, and
the internal surface of the air-tubes and cells in the
lungs is estimated at 150 square feet, or ten times the