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Enclosure 2 in No. 16.

REPORT BY DR. JOHN G. THOMSON, DIRECTOR OF PROTOZOOLOGY, LONDON SCHOOL OF TROPICAL MEDICINE, FOR THE HALF-YEAR ENDING 30TH APRIL, 1924. In addition to the routine classes in Protozoology eleven advanced students received tuition in the Department in protozoological technique, including methods of cultivation.

Miss M. J. Trifitt, M.Sc., has carried out an investigation into the intestinal protozoa of certain animals. This has resulted in the discovery of a coccidian parasite, which, from the shape and dimensions of the oocyst and sporocyst, is probably an Eimeria of a previously unknown species. Miss Triffitt has also found an amoeba in the fæces of an eland. This amoeba, in the cystic stage, showed certain points of similarity to the Entamoebae of the human intestine, such as the presence of chromatoid bodies, etc.

Mr. R. H. Harris, Government Entomologist in Zululand, made a series of dissections of the bug Rhodnius prolixus, which is the carrier of Trypanosoma cruzi in Venezuela.

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Dr. Andrew Robertson, Assistant in Protozoology, has carried out important research work on the causative organism of rat-bite fever in man. This was men- tioned in the last report, and the findings are now in course of publication. The conclusions arrived at were that the correct name for the parasite should be Spirillum minus, Carter, 1887, and that Spirocheta laverani, Breinl and Kinghorn, 1905, S. muris, Wenyon, 1905, S. morsus muris, Futaki, Takaki, Taniguchi, and Osumi, 1917, S. petit, Row, 1922, Leptospira morsus muris (Futaki, Takaki, Taniguchi, and Ósumi, 1917), Manson-Bahr, 1922, and Treponemella muris, Sangiorgi, 1922, are synonyms.

This means that, so far as is known, only one species of Spirillum occurs in the blood of mice, rats, etc., as a natural infection, and that this is the same organism which causes rat-bite fever in man.

I have continued my researches into the causation of blackwater fever. short preliminary paper was read before the Royal Society of Medicine, Tropical Section, giving a brief outline of the lines on which the work was performed. I emphasized the necessity for taking into account all the factors in the causation of this disease, e.g., the infantile endemic index, the length of stay in the black- water country, the prevalence of malignant tertian malaria, etc., and the futility of attempting to stamp out blackwater fever by concentrating on only one or a few of these factors.

Recently I gave a demonstration of microscopical preparations, which had a bearing on the etiology of the disease, before the Royal Society of Tropical Medicine and Hygiene at a laboratory meeting. Slides were shown from cultures of the malarial parasite (Plasmodium falciparum), and also blood films from cases of malignant tertian malaria and blackwater fever. The former illustrated the tendency for the malignant tertian parasite to clump round the large endothelial cells, while the latter showed the so-called "brassy" corpuscle and Stephen's and Christopher's dots.

In my work in Rhodesia I established several important facts in the relationship of blackwater fever to malaria. The co-relationship between the seasonal incidence of these two diseases in Southern Rhodesia is absolute as seen by an examination of the monthly incidence over a period of ten years.

A careful study of the morphology of the malarial parasite (p. falciparum) associated with blackwater, and the effect of this on the containing erythrocytes, shows that as the normal rings grow the hæmoglobin or the stroma of the cells Fecomes chemically altered in a marked degree, as seen by the altered staining reaction.

In my opinion it is this altered chemical reaction of the infected corpuscles which renders them capable of acting as an antigen and so producing a specific hæmolytic amboceptor. Further experiments with cultures of Plasmodium falciparum give evidence that during schizogony of the parasite there are hemolytic substances present in the peripheral blood, and this more or less confirms the observations of Simpson in Liverpool.

As soon as available, reprints of paper on rat-bite fever organism (Spirillum miausi by Dr. Robertson, and Preliminary Report on blackwater fever in Southern Rhodesia by myself will be sent to you. During the next few months I hope to complete my monograph on blackwater fever, and this also will be sent to you.

I have, &c.,

J. G. THOMSON, Director of Protozoology.

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