ith a shrill note of gladness, the infant ceases its cry, and,
after a few short sobs, usually subsides into sleep or quietude.

2454. At the same instant that the air rushes into the lungs, the valve,
or door between the two sides of the heart-and through which the blood
had previously passed-is closed and hermetically sealed, and the blood
taking a new course, bounds into the lungs, now expanded with air, and
which we have likened to a wetted sponge, to which they bear a not unapt
affinity, air being substituted for water. It here receives the _oxygen_
from the atmosphere, and the _chyle_, or white blood, from the digested
food, and becomes, in an instant, arterial blood, a vital principle,
from which every solid and fluid of the body is constructed. Besides the
lungs, Nature has provided another respiratory organ, a sort of
supplemental lung, that, as well as being a covering to the body,
_in_spires air and _ex_pires moisture;--this is the cuticle, or skin;
and so intimate is the connection between the skin and lungs, that
whatever injures the first, is certain to affect the latter.

2455. _Hence the difficulty of breathing experienced after scalds or
burns on the cuticle, the cough that follows the absorption of cold or
damp by the skin, the oppressed and laborious breathing experienced by
children in all eruptive diseases, while the rash is coming to the
surface, and the hot, dry skin that always attends congestion of the
lungs, and fever._

2456. The great practical advantage derivable from this fact is, the
knowledge that whatever relieves the one benefits the other. Hence,
too, the great utility of hot baths in all affections of the lungs or
diseases of the skin; and the reason why exposure to cold or wet is, in
nearly all cases, followed by tightness of the chest, sore throat,
difficulty of breathing, and cough. These symptoms are the consequence
of a larger quantity of blood than is natural remaining in the lungs,
and the cough is a mere effort of Nature to throw off the obstruction
caused by the presence of too much blood in the organ of respiration.
The hot bath, by causing a larger amount of blood to rush suddenly to
the skin, has the effect of relieving the lungs of their excess of
blood, and by equalizing the circulation, and promoting perspiration
from the cuticle, affords immediate and direct benefit, both to the
lungs and the system at large.

THE STOMACH--DIGESTION.

2457. The organs that eithe