ing the first half of the night to an outdoor campaign and the second half to an encampment before a wide-open window.
There is no doubt that the proximate cause of a catarrh consists in the action of some microscopic parasite that develops its germs while the resistive power of the respiratory organs is diminished by the influence of impure air. Cold air arrests that development by direct paralysis; i.e., by lethargizing and eventually destroying the vitality of the disease-germs. Towards the end of the year a damp, sultry day—the catarrh-weather par excellence—is sometimes followed by a sudden frost, and at such times I have often found that a six-hours' inhalation of pure, cold night-air will free the obstructed air-passages so effectually that on the following morning hardly a slight huskiness of the voice remains to suggest the narrowness of the escape from a two-weeks' respiratory misery.
It would be a mistake to suppose that "colds" can be propagated only by direct transmission, or the breathing of recently vitiated air. Catarrh germs, floating in the atmosphere of an ill-ventilated bedroom, may preserve their vitality for weeks after the house has been abandoned, and
