exosmose_, and is the
_exhalation_ of old physiologists.

J.

It is a well-established fact, in animal and vegetable physiology,
that membranes possess the property of allowing fluids and gases to
pass through them in either direction, and also to permit two fluids
to pass in opposite directions at the same time. This property is
designated _endosmose_ when a fluid passes from without a body inward;
and _exosmose_ when the reverse takes place. The first is called
_imbibition_. One of the most striking instances of this, in the human
system, is shown in the lungs, where carbonic acid and water pass out
through the mucous membrane of the bronchial tubes and air-cells; and
the oxygen of the air enters the blood through the same membrane. By
this process of imbibition, the oxygenation of the blood is much more
readily and faithfully accomplished; inasmuch, as by the immense
number of bronchial tubes and air-cells a larger quantity of blood is
exposed to a greater portion of air, than if the blood were directly
laid open to the atmosphere in a mass, or the air were immediately
transmitted through it.

Since the function of respiration is to free the system of superfluous
carbon and hydrogen, by union with the oxygen of the air, it follows
that the greater the amount of the products to be expelled, the larger
the quantity of oxygen will be required to effect this purpose, as we
find to be the case with those who consume large quantities of food.

The quantity of oxygen daily consumed through the lungs by an adult is
about 32.5 oz., and the carbon in the food 13.9 oz. But in order to
convert this whole amount of carbon into carbonic acid, which passes
off through the lungs and skin, 37 oz. of oxygen are required; the
remaining 4.5 oz. being absorbed by the skin. If the supply of food
remain the same, while the amount of oxygen in the inspired air is
diminished, the superfluous carbon will induce disease in the system,
as is the case of those persons who are limited in their supply of air
of a proper quality or quantity, and, consequently, have less appetite
for food than those who are abundantly supplied with air of the proper
standard of health; and in children, who proportionally consume more
food than adults, and who are more active, thereby causing a more
rapid circulation of blood, and, consequently, the removal of more
superfluous particles of matter.

In children we notice the need of air, by their disposition t