short time, sometimes after a few days, gives place to a general languor. Days, weeks, or months, according to the degree of healthfulness of the place, may pass before the organism is again in equilibrium; and this fact is so generally recognized that every traveler expects it and prepares for it. A person just landed in a distant country would be chargeable with imprudence if he neglected the precautions which experience has prescribed for diminishing as much as possible the inconveniences of this critical period. What does this mean? Simply that the organization of the new-comer must bring itself into harmony with the new medium. It makes no difference that he finds in the strange climate, in the European hotels, comforts, fare, and attentions so perfect as almost to make him forget that he has ever left his native land; he has, all the same, to go through the change which the climate works in his organism. He must adapt himself to it, become used to the new conditions. The fact of this process going on was known a long time before Darwin came into the world; and there is not, so far as I know, any doctor who has interpreted it in any other way than as a physical modification of the organism which is not limited to some superficial trait acquired by the transplanted person, but notably modifies the mechanism of the vital functions.
Two kinds of effects accompany the course of acclimatization: first, simple discomfort or climatic indisposition; and, afterward, illness proper or climatic illness. Danger, as distinguished from simple inconvenience, is the element that characterizes climatic illness. The invasion of the disease is real only in so far as the existence, or the integrity at least, of the whole organism is threatened. Till this moment, we have only indisposition to deal with; although, to speak accurately, illness and indisposition are not separated by clearly defined limits, but are rather two degrees of intensity of the same manifestation. A person is ill in the evening who was only indisposed in the morning.
If we review the vast literature that has accumulated on this subject, we shall be obliged to confess that original labors respecting these special modifications are almost wholly wanting. On the other hand, as soon as illness appears, the interest, which has now become immediate, excites the ardor of physicians; and they, by their numerous researches in this branch of the subject have given us knowledge, not only of what are generally the diseases of foreign regions, but also of their immediate causes. And, while there are still a few points in dispute, the increasing extension of wisely directed medical studies, at home and abroad, gives a well-founded hope that they will shortly be settled. Otherwise the condition of foreign medicine is but little different from that of our own; and there is no doubt that, with the progress of science, the clinics of tropical maladies will acquire an equally important development.
Our knowledge of the facts relative to climatic indispositions is not
