to their having had mild attacks of the fever during childhood, for
the children in these regions are subject to certain fevers which are
probably very mild forms of yellow fever.

Now if we kill practically all of the _Stegomyia_ so that these children
do not have this fever there will be developed, in due time, a
population most of whom are non-immune.

This freedom from the disease for some time will allow us to grow
careless in regard to fighting the mosquitoes. They will be allowed to
increase and by some chance the yellow fever will again be introduced
and there will then be very grave danger of most extensive and
destructive epidemics.

DANGER OF THE DISEASE IN THE PACIFIC ISLANDS

I have already referred once or twice to the conditions in many of the
Pacific tropical islands. In some of these various species of
_Stegomyia_ are abundant, and in some _Stegomyia calopus_ is the most
abundant and troublesome form. All the natives of these islands are
non-immune because there has never been any yellow fever there. Unless
extraordinary care is taken the disease will be introduced there sooner
or later and the results are sure to be most appalling. The climatic and
sanitary conditions and the habits of the people are ideal for the
development and spread of the disease, and what I have seen of the
conditions on some of these islands convinces me that it would be almost
impossible to control the disease before it had a chance to kill a large
percentage of the population.

With the opening of the Panama Canal these things become more possible.
Heretofore, the shipping to these regions has not been from ports where
yellow fever was endemic or even likely to be epidemic. But unless the
yellow fever is kept out of the canal zone, the danger will be many fold
what it is now.

The white man has already carried enough misery to these island peoples
in the way of loathsome diseases, and it is to be hoped that this,
another great curse, will not be carried to them with our civilization,
the beneficial results of which have been so often very justly
questioned.

What I have said in regard to these islands applies with equal force and
in some instances with even greater force to parts of Asia, the Eastern
Archipelago and other places.

CHAPTER IX

FLEAS AND PLAGUE

Plague has always been one of the most dreaded diseases, and when we
read of its ravages in the old world and the utter helplessness of the
peop