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ENTLEMEN: 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 photomicrographs of the principal pathogenic bacteria, including the micrococcus 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 mischief-making micro-organisms. In speaking of the pathogenic protozoa I shall devote special attention to the hæmatozoon 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 Grâce.

In my work on Malaria and Malarial Diseases, published in 1884, I 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 elements 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