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 140 THE SCIENTIFIC MONTHLY

Hospital^ and others^ but without Buccess. His natural inference was that either the disease is not inoculated by mosquito bites or that he had not got hold of the right kind of mosquito for the purpose. In April, 1896, he was sent to Ootacamund, a great hill station in the Nilgiri Hills, 8,000 feet above the sea level, and here among the tea and coffee planta- tions at the foot of the malarial Sigur Ghat, a trench-like hollow in the hills, he made his first step in advance, for here he found and began to concentrate his attention upon the dapple-winged Anopheles mosquito, which was to prove the true vector of the disease. Ordered back to Secunderabad in July, 1897, he repeated all his experiments upon the gray and brindled mosquitoes, without success, but did not get hold of any specimens of Anopheles until August 15. In the stomach of one of these, he found, on August 20, a delicate circular cell containing minute granules of a black substance like the melanin pigment, discovered by Meckel in 1847, which was shown by Virchow and Prerichs to be the essential pathological product of malarial fever, and is found in the malarial parasite. The next morning, he found in his eighth and last Anopheles similar bodies, only much larger.

Both insects had been bred from larve in captivity; both had been fed for the first time on the same person — a case of malaria; no such objects as these pigmented cells — as I then called them — ^had ever before been seen in the hun- dreds of mosquitoes examined by me ; the objects lay, not in the stomach cavity of the insect, but in the thickness of the stomach wall; all contained a number of black granules precisely similar in appearance to those contained by the parasites of malaria, and quite unlike anything which I had ever seen in any mosquito previously. Lastly these two mosquitoes were the first of the kind which I had ever tested. . . . These two observations solved the malaria problem. They did not complete the story, certainly; but they fumiEdied the clue. At a stroke they gave both of the two unknown quantities — ^the kind of mosquito implicated and the position and appearance of the parasites within it. The great difficulty was really overcome; and all the multitude of important results which have since been obtained were obtained solely by the easy task of follow- ing this clue — a work for children.?

Shortly after confirming these results, Eoss received peremptory orders to proceed to Kherwara in Eajputana, a petty non-malarial sta- tion, 1,000 miles distant, which he describes as *'my Elba — ^almost my lie du Diable," for here his researches were interrupted until February, 1898, when he was given a six-months detail to investigate malaria and kala azar in Calcutta and Assam, In the meantime, W. G. MacCallum, at the Johns Hopkins Hospital, had discovered that the motile filaments of Halteridium, a parasite in birds, are agents in sexual conjugation, and in 1898, MacCallum and Eugene L. Opie demonstrated the same thing for the malarial parasite. Working with Halteridium and Proteosoma, both malarious parasites of birds, Ross proved at Calcutta on March 20, that Proteosoma can be transmitted from bird to bird by

7 Boss, Jawr. Boy, Army Med. Corps, Lond., 1905, IV., 651.

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