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 ROSS AND MALARIAL FEVER 137

Teveis/' in which these diseases are attributed to minute fungi. This essay is a landmark in the history of the doctrine of contagion, but, for OUT purpose, the most important sentences in it are the following, refer- ring to the causation of malarial fevers :

Whatever may be their cause, it seems to have activitj almost solely at night. Darkness appears to be essential to either its existence or its power.

Yet, strange to say, Mitchell, carried away by his theory of a fungous cause, says nothing whatever about mosquitoes, which were coming to be recognized more and more as agents in the production of both malarial and yellow fevers. In an old ordinance of Freetown, Sierra Leone, dated 1812, and cited by Kennan, the inhabitants (mostly freed slaves) are enjoined to keep the road in front of their plots in good condition in order to prevent the formation of " stagnant pools which generate dis- ease and mosquitoes over the town" (Eoss). In 1848, Dr. Josiah C. Nott, of Mobile, Alabama, advanced the provisional theory that yellow fever and malarial fever are of " probable insect or animalcular origin." It is sometimes asserted that Nott regarded the mosquito causation of malarial fever as proven. The only statement in his brilliant but rambling essay which suggests anything of the kind is the title of the paper itself, viz., " Yellow Fever contrasted with Bilious Fever — Eeasons for believing it a disease sui generis. Its mode of Propagation — ^Eemote Cause — Probable insect or animalcular origin, etc."^

The explanation of Nott^s statement is simple. He got his theory of malaria, as every one else did, from Lancisi. In 1854, Louis Daniel Beauperthuy, a French physician residing in Venezuela, assigned a defi- nite species of mosquito as the cause of yellow fever, holding that the poison is injected under the skin by the insect, as in snake bite. In 1866, Salisbury attributed the causation of malarial fever to spores of the vegetable family Palmella, and in 1879, Edwin Klebs and Tommasi- Crudeli announced the discovery of a Bacillus malaricB, neither of which availed as the true cause. The next few years witnessed a sudden leap in knowledge. On November 6, 1880, Alphonse Laveran, a French army surgeon, working at Constantine, Algeria, discovered the parasite of malarial fever, and in 1881, described three of its forms. In 1881 also. Dr. Carlos J. Finlay, after making a series of careful bionomic observa- tions and some inoculation experiments, announced that yellow fever is transmitted from man to man by a special species of mosquito (Siegomyia^ calofus)^ a theory which was to be proven in the most rigorous way by Major ffalter Eeed, of the XJ. S. Army Commission, and

on this point the essay of Dr. Juan Guiteras, ''Insect-borne Diseases in Pan- America, '' Habana, 1915, p. 33.
 * J. C. Nott, New Orleans Med, and Surg. Jour., 1847-8, IV., 563-601. See

«!Finlay, An. r. Acad, de den. med. . . . de la Habana, 1881-2, XVII., 147-169.

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