5o8 THE POPULAR SCIENCE MONTHLY. 



short time, sometimes after a few days, gives place to a general lan- 

 guor. Days, weeks, or months, according to the degree of healthf ul- 

 uess 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 incon- 

 veniences of this critical period. What does this mean ? Simply that 

 the organization of the new-comer must bring itself into hannony with 

 the new medium. It makes no difference that he finds in the strange 

 climate, in the European hotels, comforts, fare, and attentions so per- 

 fect 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, ill- 

 ness proper or climatic illness. Danger, as distinguished from sim- 

 ple 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 de- 

 fined limits, but are rather two degrees of intensity of the same mani- 

 festation, 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 sub- 

 ject, 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 im- 

 mediate, 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 dis- 

 pute, 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 dif- 

 ferent 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 



