A system of medicine by many authors.

  • Allbutt, Thomas Clifford editor, Sir.
Date:
1899
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Licence: Public Domain Mark

Credit: A system of medicine by many authors. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    intended for life inside the human body, the other for life outside the human body, the latter cycle being accomplished possibly in some suctorial animal. In 1894 (11), and again inl896(ll), I ventured to interpret the well- known fact that it is not until the crescent body of the sestivo-autumnal, and certain full-grown forms of the tertian and quartan infections have left the human body that they proceed to exflagellation, as signifying that this phase, which is common alike to the malaria parasite of man and to the malaria-like parasites of birds, is intended to subserve the extra- corporeal life of the parasites concerned; in other words, that this is the first step in their extra-corporeal existence. Further, basing my argument on the close parallel subsisting between F. nocturna and the malaria para- site as regards their anatomical position as blood parasites, their biological necessities, their geographical distributions, and their development at a later stage of distinct evidences of locomotive and penetrating faculties, I concluded that it is with the malaria parasite as with the filaria; that some extraneous agency is required to remove it from the human blood- vessels ; that this agency is the mosquito ; that, after ingestion, it assumes locomotive characters and penetrates the tissues of the mosquito; that it becomes parasitic for a time in this insect; and, just as with the filaria, that only particular species of mosquito are effective hosts. Major Ronald Ross, I.M.S. (16), embraced these ideas, and, in a series of brilliant observa- tions and experiments characterised by a sagacity, a resourcefulness, and a perseverance rarely excelled, has thoroughly established their correct- ness, in part as regards the malaria parasites of man, and completely as regards one of the malaria-like parasites (proteosoma) of birds. Important supplementary observations have been made by Dr. MacCallum. Ross's work has been fully confirmed by Grassi, Bignami, Bastianelli (1), Celli, Koch, and Daniels. Working on the lines so plainly indicated by Ross, the Italian observers have filled in the details which circumstances com- pelled him to leave undescribed in his human malaria work; they have also determined some of the species of mosquito concerned in the propaga- tion of the malaria parasites. Such is a brief summary of the history of a discovery pregnant with important practical results to mankind. For a fuller account, and for a complete bibliography, the reader is referred to Dr. Nuttall's recent essays (14). Ross, in his earlier observations, made out the significant fact that when a mosquito ingests the blood of a malarious subject in whom the crescent parasite was present, practically all the ingested crescents rapidly become spheres, and a large proportion of them proceeds to exflagella- tion. MacCallum subsequently showed that in halteridium (a malaria- like intracorpuscular parasite of crows, pigeons, and other birds) the bodies corresponding to the crescent-derived spheres of human malaria are of two kinds, alike in size and shape, but different in function and somewhat in appearance, one type of sphere being hyaline, the other granular. He found that it is the hyaline spheres only which produce