feet higher, where
they are safe, for no _Stegomyia_ have ever been found there.

They claim there that the yellow fever mosquito does not bite during the
daytime after she has laid her eggs, and that she will not lay her eggs
until about three days after she has fed on blood, therefore a
_Stegomyia_ that bites during the day will not carry the yellow fever
because she is too young. This seems to explain why the fever cannot be
contracted by being bitten by a mosquito in the daytime. Certain other
experiments, however, have given different results so that as far as we
know it is not safe to be bitten at any time by such a mosquito in a
region where the disease is endemic or where it is epidemic.

In the main the work of the French Yellow Fever Commission working in
Rio de Janeiro has confirmed the findings of the American Commission.
One interesting special thing that the French Commission seems to have
established is that the female may transmit the infecting power to her
offspring, so that it would be possible for a mosquito that had never
bitten a yellow fever patient to be capable of infecting a non-immune
person. While all this is very probable in the light of what we know of
the disease and the way in which other diseases caused by similar
organisms may be transmitted by the parent to the offspring, yet the
most conservative investigators are waiting for further proof.

HABITS OF STEGOMYIA

The whole fight against yellow fever, then is directed, as we have seen,
against the mosquito, _Stegomyia calopus_. The habits of this species
are such as to make it easy in some respects to combat. It is seldom
found far away from human habitation. The adults will not fly far. Once
in a house they usually stay there except when they leave to deposit
their eggs.

On the other hand, some of these same habits make it all the more
dangerous. It will breed in almost any kind of water, no matter how
filthy, and a very small amount will suffice. Thus any leaks from
water-pipes or drains, cisterns, small cans of water or any such places
may become dangerous breeding-places. If conditions are unfavorable
there will often be developed small individuals which can easily make
their way through ordinary mosquito-netting.

Dr. Manson has pointed out an interesting possible result of the crusade
that is now being waged against the yellow fever mosquitoes. The
immunity of the people native to the endemic regions is supposed to be
due