DISCOVERY OF MOSQUITO ROLE 195 
the Philosophical Society of Washington in 1882 and subsequently published in 
the Popular Science Monthly for September, 1883 (vol. 23, pp. 644-658). This 
paper attracted much attention in this country, but the author himself realized 
that the arguments brought forth could not be held to prove the theory. He said, 
however, “ they may go so far as to initiate and encourage experiments and ob- 
servations by which the truth or fallacy of the views held may be demonstrated.” 
The main arguments used by King were substantially as follows: 
1. The malarial season corresponds to the season of mosquito abundance. 
2. Malarial country is suitable for mosquito breeding. 
3. Similar conditions afford protection against malaria and against mos- 
quitoes. 
4, Exposure to night air means exposure to mosquitoes. 
5. Influence of occupation. Soldiers, tramps and fishermen are particularly 
susceptible to malaria and are especially exposed to mosquitoes at night. 
6. Turning up the soil or making excavations in previously healthy districts 
is often followed by malaria, but this turning up of the soil gives opportunities 
for water to accumulate and for mosquitoes to breed. 
%. Coincidence of malaria and mosquitoes. 
The scientific study of malaria may be said to begin with the far-reaching dis- 
covery of the malarial parasite. Laveran, on November 6, 1880, first recog- 
nized the organisms as minute protozoan parasites of the red blood-corpuscles. 
He furthermore discovered the flagellate and crescent forms of the parasites 
which were afterwards shown to be sexual phases of it. The idea that the in- 
fection was brought about through mosquitoes was suggested by Laveran in 
1884; by Robert Koch in 1892; and by Sir Patrick Manson in 1894. The 
Italians Bignami and Mendini mentioned it in 1896, and Grassi in 1898. 
Bignami and Dionisi are said to have conducted mosquito experiments which, 
however, turned out negative, in 1893 and 1894. Manson, who had already 
proved that mosquitoes acted as the transmitters in filariasis, pointed out that 
there was probably a similar relation in malaria. He expressed his belief that 
the flagella were spores and that they underwent further development in the 
mosquito. 
Following the publication by Manson, in 1894, of his theoretical induction that 
the gametes of malaria undergo further development in mosquitoes, Dr. Ronald 
Ross, of the Indian Medical Service, commenced, in May, 1895, certain re- 
searches in the hope of demonstrating this hypothesis by practical experiment. 
He was then stationed in India, and almost immediately proof that the gametes 
undergo their peculiar changes more readily in the stomach of mosquitoes than 
elsewhere was obtained. Then followed two years of arduous work with mos- 
quitoes of the genus Culex without the desired results. In August and Sep- 
tember, 1897, however, in Secunderabad, he succeeded in following the develop- 
ment of the parasites in Anopheles mosquitoes, and his results were published 
in the British Medical Journal for December 18, 1897, and February 26, 1898. 
The following year he was unable to work with human malaria on account of 
the public agitation against plague inoculation in Bengal, so he determined to 
14 
