consumption alone, in civilized communities, while in the Orient the
pneumonic form of the plague is a greater scourge than cholera.

It has even been suggested that there may possibly be a historic or
ancestral reason for this weakness to attack, and one dating clear back
to the days of the mud-fish. It is pointed out that the lung is the last
of our great organs to develop, inasmuch as over half of our family tree
is under water. When our mud-loving ancestor, the lung-fish (who was
probably "one of three brothers" who came over in the Mayflower--the
records have not been kept) began to crawl out on the tide-flats, he had
every organ that he needed for land-life in excellent working condition
and a fair degree of complexity: brain, stomach, heart, liver, kidneys;
but he had to manufacture a lung, which he proceeded to do out of an old
swim-bladder. This, of course, was several years ago. But the lung has
not quite caught up yet. The two or three million year lead of the other
organs was too much to be overcome all at once. So carelessly and
hastily was this impromptu lung rigged up that it was allowed to open
from the front of the gullet or [oe]sophagus, instead of the back, while
the upper part of the mouth was cut off for its intake tube, as we have
already seen in considering adenoids, thus making every mouthful
swallowed cut right across the air-passages, which had to be provided
with a special valve-trap (the epiglottis) to prevent food from falling
into the lungs.

So, whenever you choke at table, you have a right to call down a
benediction upon the soul of your long departed ancestor, the lung-fish.
However applicable or remote we may regard "the bearin's of this
observation," the practical and most undesirable fact confronts us
to-day that this crossing and mutual interference of the air and the
food-passages is a fertile cause of pneumonia, inasmuch as the germs of
this disease have their habitat in the mouth, and are from that
lurking-place probably inhaled into the lung, as is also the case with
the germs of several milder bronchitic and catarrhal affections.

It may be also pointed out that, history apart, our lung-cells at the
present day are at another disadvantage as compared with all the other
cells of the body, except those of the skin; and that is, that they are
in constant contact with air, instead of being submerged in water.
Ninety-five per cent of our body-cells are still aquatic in their
habi