360 POPULAR SCIENCE MONTHLY. 



MALAEIA.* 



By GEO. M. STERNBERG, M.D., LL.D., 



SURGEON-GENERAL, V. 8. ARMY. 



IN my address as president of the Biological Society, in 1896, the sub- 

 ject chosen was 'The Malarial Parasite and other Pathogenic Proto- 

 zoa.' This address was published in March, 1897, in the Popular 

 Science Montlht, and I must refer you to this illustrated paper for a 

 detailed account of the morphological characters of the malarial parasite. 

 It is my intention at the present time to speak of 'Malaria' in a more gen- 

 eral way and of the recent experimental evidence in support of Manson's 

 suggestion, first made in 1894, that the mosquito serves as an intermedi- 

 ate host for the parasite. The discovery of this parasite may justly be 

 considered one of the greatest achievements of scientific research during 

 the nineteenth century. Twenty-five years ago the best-informed physi- 

 cians entertained erroneous ideas with reference to the nature of 

 malari i and the etiology of the malarial fevers. Observation had taught 

 them that there was something in the air in the vicinity of marshes in 

 tropical regions, and during the summer and autumn in semi-tropical 

 and temperate regions, which gave rise to periodic fevers in those ex- 

 posed in such localities, and the usual inference was that this something 

 was of gaseous form — that it was a special kind of bad air generated in 

 swampy localities under favorable meteorological conditions. It was 

 recognized at the same time that there are other kinds of bad air, such as 

 the offensive emanations from sewers and the products of respiration of 

 man and animals, but the term malaria was reserved especially 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 this 

 term is a misnomer. There is no good reason for believing that the air 

 of swamps is any more deleterious to those who breathe it than the air of 

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

 over, the stagnant pools, which are covered with a 'green scum' and from 

 which bubbles of gas are given off, have lost all terrors for the well- 

 informed man, except in so far as they serve as breeding places for mos- 

 quitoes of the genus Anopheles. The green scum is made up of harmless 

 algae such as Spirogyra, Zygnema Protococcus, Euglena, etc.; and the 

 gas which is given off from the mud at the bottom of such stagnant pools 

 is for the most part a well-known and comparatively harmless compound 



* Annual address of the president of the Philosophical Society of Washington. Delivered 

 under the auspices of the Washington Academy of Sciences, on December 8, 1900. 



