ent in the United
States five thousand victims of pellagra, with the number constantly
increasing, although physicians of standing make estimates largely in
excess of this.

Apparently preventive measures must consist in eliminating the
possibility of the use of spoiled corn. Indications are that the disease
appears only when such corn has been used, and in parts of Mexico where
corn is always roasted before being used, pellagra is never known. It
has been described as a disease of the poor, because the disease has
flourished chiefly in districts where poverty is so extreme that corn,
and spoiled corn at that, is the only food within reach. Usually, where
a mixed diet with meat is possible, pellagra never appears. In other
places, as in Italy, where the peasants live on a porridge of corn meal
cooked in great potfuls, a week's supply at a time, and during the week
exposed to dirt and flies and often spoiled before eating, pellagra is
most common. Experiments have shown that in these districts, by
excluding corn from the diet and furnishing a substantial fare, the
disease has been banished. Unfortunately, the taint of the disease
passes from parent to child and even to the third and fourth generation,
and the physical deformities commonly seen in pellagrous districts are
due to this hereditary taint. Dr. Babcock, Superintendent of the City
Hospital at Columbia, South Carolina, after discussing the disease, sums
up by saying, "Pellagra is a fact, and the United States is facing one
of the great sanitary problems of modern times."

_Bubonic plague._

The bubonic plague, or "The plague," as the importance of the disease
has caused it to be called, is one of the oldest of known epidemics. In
the third century it spread through the Roman Empire, destroying in many
portions of the country nearly one-half of the people. Its immediate
origin is a bacillus causing symptoms similar to blood poisoning,
although in some cases, where the lungs are attacked, the disease has
some of the characteristics of pneumonia.

A description of this disease is included here because, while bacterial
in its nature, it is transmitted largely, if not entirely, by fleas and
by a particular species of flea known as the rat flea. These fleas
harbor the plague bacilli in their stomachs and inject them into the
bodies of those they bite, in the same way that the anopheles or
stegomyia mosquito transmits malaria or yellow fever. Elaborate
experiments