t such levels above the surface of the water, that the _Anopheles_ most
delights to disport himself. Furthermore, while all raw or misty air is
"bad," the night air is infinitely more so than that of the day, because
this is the time at which mosquitoes are chiefly abroad. In fact, there
can be little doubt that this is part of the foundation for that rabid
and unreasonable dread of the night air which we fresh-air crusaders
find the bitterest and most tenacious foe we have to fight. We have
literally discovered the Powers of Darkness in both visible and audible
form, and they have wings and bite, just like the vampire.

It was also a widespread belief in malarial regions that the hours when
you are most likely to "git mylary inter yer system" were those just
before and just after sundown; and now entomologists inform us that
these are precisely the hours at which the _Anopheles_ mosquito, the
only genus that carries malaria, flies abroad.

Of course, a number of popular causes, such as bad drainage, the
drinking of water from shallow surface wells, damp subsoils under the
houses, and especially that peculiarly widespread and firmly held
article of belief that new settlements, where large areas of prairie sod
were being freshly upturned by the plough, were peculiarly liable to
the attack and spread of malaria, had to go by the board,--with this
important reservation, however, that almost every one of these alleged
causes either implied or was pretty safe to be associated with pools or
swamps of stagnant water in the neighborhood, which would furnish
breeding-spots for the mosquitoes.

The discovery explains at once a score of hitherto puzzling facts as to
the distribution of malaria. Why, for instance, in all tropical or other
malarious countries, those who slept in second and third story bedrooms
were less likely to contract the disease, supposedly because "bad air
didn't rise to that height," is clearly seen to be due to the fact that
the mosquito seldom flies more than ten or twelve feet above the level
of the ground or marsh in which he breeds, except when swept by
prevailing winds. It also explained why in our Western and Southwestern
states the inhabitants of the houses situated on the south bank of a
river, though but a short distance back from the stream, would suffer
very slightly from malaria, while those living upon the north bank, half
a mile back, or even upon bluffs fifteen or twenty feet above the water