A research into the production, life and death of crescents in malignant tertian malaria, in treated and untreated cases, by an enumerative method ; The leucocytes in malarial fever : a method of diagnosing malaria long after it is apparently cured / by David Thomson.
- Thomson, D. (David)
- Date:
- 1911
Licence: Public Domain Mark
Credit: A research into the production, life and death of crescents in malignant tertian malaria, in treated and untreated cases, by an enumerative method ; The leucocytes in malarial fever : a method of diagnosing malaria long after it is apparently cured / by David Thomson. Source: Wellcome Collection.
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![in the former case no crescents were produced, whereas in the latter, 286 crescents per c.mm. of blood appeared. Again, as shown in Table A, the cases with very numerous asexual parasites produced on the average fewer crescents than cases with much less numerous asexual parasites. These facts would appear to bring strong evidence against Mannaberg’s hypothesis. The following quotation is from Stephens and Christophers [1908] :—‘ The sexual cycle, it has been thought, commences in the blood when the conditions are unfavourable for the continuance of the asexual cycle, and, in fact, has been taken as a sign that the patient has already developed immunity against the fever-producing young parasites (spores). Thus it is well known that in malignant tertian the sexual forms, gametes or crescents, first appear a week to ten days after the first febrile attack. If this view be true, then it follows that the gametes develop from forms already present in the system, viz., the asexual forms, and possibly the divergence into sexual forms takes place from the youngest form of the parasite, 1.e., the spore. But it is possible that the divergence takes place at a stage previous to the youngest form of the parasite, 1.e., at a stage immediately preceding the entry of the sporozoits into the blood, so that we have from the first indifferent and sexual forms present, involving indeed the existence of three kinds of sporozoits. Sexual development has been supposed to proceed mainly in the internal organs, e.g., the bone marrow, but it is being gradually recognised that young forms “of gametes are also found in the circulation.’ This research would appear to support the idea that the crescents are developed from the asexual spores when a certain amount of immunity has developed, but it seems to me that they do not come from special asexual spores, but that they arise merely owing to a transformation of an ordinary asexual spore into a sexual parasite. I will give evidence to show that the development of immunity is necessary for their production, and I fail to see why, if they do develop from special spores they cannot be produced at any time independently of immunity. There seems to be little doubt also that they develop chiefly in the internal organs, and when completely developed they appear suddenly in the peripheral blood ; for, although small undersized crescents are sometimes seen, yet their occurrence in the peripheral blood is rare. I have never seen](https://iiif.wellcomecollection.org/image/b33445059_0005.jp2/full/800%2C/0/default.jpg)
