242 THE POPULAR SCIENCE MONTHLY. 



impressed with the belief that malaria is an actual or material poison- 

 ous substance. To Homer it was the arrows of Apollo in anger, to 

 the mediaeval folk-lore it was the mischief of elves and sprites ; and, 

 if scientific medicine does not now permit us to personify the malaria, 

 it teaches us at least to materialize it. Although the fevers which 

 malaria produces are quite unlike the fevers that are contagious or 

 communicable, the present scientific guides of the profession are re- 

 solved to find a material virus or poison as the cause of them. The 

 malarial poison was sought for, in the early days of chemistry, among 

 the various gases of the marsh, but the chemical search proved fruit- 

 less. When the microscope came in, the miasm was diligently looked 

 for in the soil of malarious localities and in the vapors overhanging 

 them. From 1849 to the present year, some twenty different vege- 

 table organisms or their spores, of very various degrees of complexity, 

 have been described each in its turn as the malarious miasm and as 

 the specific cause of remittent and intermittent fevers ; and the quest 

 for a material substance assumed to be the cause of malarial fever is 

 regarded with much favor in the best scientific circles. Meanwhile a 

 body of opinion, which takes due account of all the manifold asso- 

 ciated circumstances of malaria throughout the world, has been form- 

 ing, and yearly growing in volume, that there is no malarious miasm 

 at all ; that " malaria," indeed, is a profound disorganization of the 

 nervous mechanism that presides over the temperature of the body ; 

 and that this upsetting of the heat-regulating center is likely to happen 

 when the body has been exposed during the day to extreme solar heat 

 and to fatigue, and exposed at sundown and in the night to the tropi- 

 cal or sub-tropical chill, which will be severe in proportion to the rapid 

 cooling of the ground and the amount of vapor condensed in the low- 

 est stratum of the air. There is no more beautiful mechanism in 

 nature than that which keeps man's internal heat always about 98° 

 day and night, summer and winter, in the Arctic regions or in the 

 tropics ; but even that most wonderful of all self -adapting pieces of 

 mechanism, if it be taxed too much, as by extremes of day and night 

 temperature, will get out of gear ; and a fever, still retaining some- 

 thing of the diurnal periodicity, will be the result. iN'o one can read 

 the powerful criticism * of Surgeon-Major Oldham, of the Indian Medi- 

 cal Service, without discovering this rational explanation of malaria 

 to have the best of the facts and the best of the logic on its side. 



The decision of this point of theory one way or another has the 

 most momentous issues, not so much for the treatment of malarious 

 fever as for its prevention. It is, in short, a question, on the one 

 hand, of common prudence in warm countries, more often moist than 

 arid, and more often level than mountainous, against exposure of the 

 body to the direct action of the sun's rays and to the nightly chill 



* "What is Malaria? and why is it most intense in Hot Climates?" London, 1871, 

 8vo, pp. 186. 



