628 POPULAR SCIENCE MONTHLY. 



THE MALARIAL PARASITE AND OTHER 

 PATHOGENIC PROTOZOA.* 



By GEOEGE M. STERNBERG, M. D., LL. D., 



SURGEON GENERAL, UNITED STATES ARMY. 



GENTLEMEN : My presidential address last year had for its 

 subject The Practical Results of Bacteriological Researches, 

 and at its conclusion I showed you upon the screen photomicro- 

 graphs of the principal pathogenic bacteria, including the micro- 

 coccus of pneumonia ; the micrococci concerned in the production 

 of boils, abscesses, wound infection, puerperal fever, erysipelas, 

 etc. ; the bacilli of tuberculosis, of diphtheria, of typhoid fever, 

 of glanders, of anthrax, of influenza, of tetanus, of leprosy ; the 

 spirillum of relapsing fever, the spirillum of Asiatic cholera, and 

 various other pathogenic bacteria. These micro-organisms are 

 now generally recognized as belonging to the vegetable kingdom, 

 and as a specialist in this department of scientific investigation 

 your president may perhaps be considered a botanist in a small 

 way. But the Biological Society includes among its members 

 many distinguished specialists in that branch of natural history 

 which relates to the animal kingdom, and I think it due to the 

 zoologists to show that the botanists have no monopoly of mis- 

 chief-making micro-organisms. In speaking of the pathogenic 

 protozoa I shall devote special attention to the htematozoon which 

 is now recognized as the specific cause of the malarial fevers ; and 

 in consideration of the importance of this blood parasite from a 

 sanitary point of view, as well as of the interest which attaches 

 to it from a biological standpoint, I shall occupy a little time in 

 giving you an account of its discovery and the grounds upon 

 which it is accepted by well-informed pathologists as the specific 

 infectious agent in the class of fevers referred to. 



The malarial parasite was discovered in 1880 by Laveran, a 

 surgeon in the French army, at that time stationed in Algeria, 

 but now a professor in the military school at Val de Grace. 



In my work on Malaria and Malarial Diseases, published in 

 1884, 1 refer to Laveran's alleged discovery as follows : 



" According to this observer, there are found in the blood of 

 patients attacked with malarial fever pigmented parasitic ele- 

 ments which present themselves under three principal aspects. 

 This parasite is said to be a kind of animalcule which exists at 

 first in an encysted state. In the blood these organisms present 

 themselves as motionless, cylindrical, curved bodies, which are 



* Presidential Address delivered before the Biological Society of Washington, December 

 5, 1S96. 



