MALARIAL FEVERS 235 



resulting in the formation of a multitude of minute 

 spore-like bodies which are found in the salivary 

 glands of the insect. 



Twenty-five years ago the best-informed physicians 

 entertained erroneous views with reference to the 

 nature of "malaria" and the cause of the malarial 

 fevers. Observation had taught them that there is 

 something in the air in the vicinity of marshes in 

 tropical regions, and during the summer and autumn 

 in semitropical and temperate regions, which gives 

 rise to periodic fevers in those exposed in such 

 localities ; and the usual inference was that this 

 something was of gaseous form that it was a 

 special kind of bad air (malaria) generated in 

 swampy localities under favourable meteorological 

 conditions. It was recognised at the same time that 

 there are other kinds of bad air, such as the offensive 

 emanations from sewers and the products of respira- 

 tion of men and animals ; but the term malaria was 

 reserved for the kind of bad air which was supposed 

 to give rise to the so-called malarial fevers. In the 

 light of our present knowledge it is evident that the 

 term is a misnomer. There is no good reason for 

 believing that the air of swamps is any more dele- 

 terious to those who breathe it than the air of the 

 sea-coast or that in the vicinity of inland lakes and 

 ponds. Moreover, the stagnant ponds, which are 



