Another mystery was solved--and what a flood of light it did pour upon our speculations as to the how and wherefore of the catching of malaria! In some respects it curiously corroborated and increased our respect for popular beliefs and impressions. While "bad air" had nothing to do with causing the disease, except in so far as it was inhabited by songsters of the _Anopheles_ genus, yet it was precisely the air of marshy places which was most likely to be "bad" in this sense. So that, while in one sense those local wiseacres, who would point out to you the pearly mists of evening as they rose over low-lying meadows and bottom-lands, and inform you that there before your very eyes was the "mylary just a-risin' out of the ground," were ludicrously mistaken, in another their practical conclusion was absolutely sound; for it is in just such air, at 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.