OF MALARIA. 27 



fact that exposure for a single hour, at night, sometimes 

 produces an almost immediate attack in some persons, 

 whilst in others it creates a tendency to disease, not ac- 

 tively expressed until the lapse sometimes of months. It 

 will be acknowledged, too, that in that hour there may be 

 observed no unusual or contrasted conditions of the air, 

 either as to temperature or moisture. 



On the western coast of Africa the sickness reaches its 

 maximum in the height of the rainy season, when the 

 diurnal temperature and moisture are almost invariable. 

 Whilst on the coast of Brazil the same meteoric pheno- 

 mena are perfectly innocuous. 



Like every other theory, therefore, this o*e owes its 

 plausibility rather to the defects of a former hypothesis 

 than to its own value. 



Daniel in England, and Gardiner in this country, have 

 adopted, with slight modification, an opinion of Ramman- 

 zani, that marsh exhalations owe their injurious activity 

 to sulphureous emanations. It is not enough to demon- 

 strate their destructiveness, that their presence in minute 

 quantity may be detected in paludal air; for the same 

 argument would equally favor the reference of marsh 

 fevers to any one of the many other gases or vapors found 

 in the same places. The innocuous qualities of these as 

 manifested elsewhere, is not less than those of the com- 

 pounds containing sulphur. Moreover, the sulphureous 

 localities of the sickly island of St. Lucia, are its only 

 salubrious places. (Evans.) Cities, too, which abound in 

 sulphur-products, should not, according to this theory, 

 enjoy the immunity from agues for which they are every- 

 where noted. 



Immediately around the sulphur works and factories for 

 making gunpowder and sulphuric acid, the vegetation and 

 the ague disappear together. Facts of the same import 



