A malaria problem.

Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: A malaria problem. Source: Wellcome Collection.

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    being the transference of the young parasite from the blood in the stomach of the mosquito fed on malaria blood to some cell in this insect where, in due course, it would enter on a coccidium-like evolution, and become parasitic in the mosquito. In other words, he regarded the malaria parasite as a parasite common to man and the mosquito, circum¬ stances determining which host it should enter, the parasite itself being capable of living in either indifferently and in¬ definitely, and of passing from one to the other. Surgeon-Major Ronald Ross was so impressed with the practical and scientific importance of this hypothesis that on his return to India, some two years ago, he set to work with skill and determination to establish or confute it. By feeding mosquitos on crescent-containing blood he first made the important observation that the great majority of crescents were rapidly transformed into flagellated bodies very soon after entering the stomach of the insect, and that subse¬ quently the flagella—or, as he prefers to call them, fiagellula —broke loose and became free. He also observed that the flagella attacked cells—leucocytes. Moreover, he proved that it was not the influence of the blood vessels or of any con¬ dition peculiar to the human body that prevented the ex¬ flagellation of the crescents—or, as he calls them, fiagellula cysts—from evolving prematurely while in the human body. He showed that by surrounding a drop of crescent - containing blood with vaseline, the cres¬ cents permanently remained crescents, and that they did not proceed in development and evolve flagella until the blood was exposed to the air or to moisture (confirming Marshall’s observations). This is a most significant fact as tending to show that the crescent depends on extracorporeal conditions for its start in development. For a long time Ross could get no further. He failed to trace the future pro¬ gress of the flagellum in the mosquito. In the paper which we publish to-day we may have the explanation of his fail¬ ure. Possibly he was working with the wrong species of mosquito, for now he tells us that at last, in a species of insect which hitherto he had not an opportunity of working with, he has found in certain cells in the stomach wall peculiar pigmented bodies which may turn out to be the maturing form of the extracorporeal or mosquito phase of the malaria parasite. If he has not quite proved that the malaria flagellum or flagellated spore enters a mosquito cell, he has now almost certainly proved, as attested by Mr. Bland Sutton, Dr. Thin, and Dr. Patrick Manson, that a product —melanin—characteristic of the malaria parasite is to be found in certain cells in the walls of the stomach of a certain