Societies and Academies


    LONDON. Royal Society, May 5.—Mr. A. B. Kempe, Inasurer ana vice-president, in the chair.—Colonel Sir David Bruce, Captains A. E. Hamerton and H. R. Bateman, and Captain F. P. Mackic: The development of trypanosomes in tsetse-flies. Until the end of 1908 it was believed that tsetse-flies acted merely as mechanical agents in the transference of trypanosome diseases. The parasite was supposed to be carried by the fly in the same way that vaccine lymph is carried—on the point of a lancet from one child's arm to another. The limit of time of infectivity of the fly was placed at forty-eight hours, and it was believed that if an infected area were emptied of its sleeping-sickness inhabitants for a couple of days, it would then be quite safe for healthy persons to enter it. At the end of 1908 Kleine made the discovery that a tsetse-fly could convey a trypanosome for some fifty days after the fly had fed on an infected animal. The experiments were carried out on these lines in Uganda. Both lake-shore and laboratory-bred flies (Glossina palpalis) were used, and various trypanosome diseases besides sleeping sickness were experimented with. Tsetse-flies are numerous on the lake-shore, 500 or more being caught every day by a few fly-boys. The flies brought up from the lake-shore were found to be naturally infected with at least two species of pathogenic trypanosomes, so that it was afterwards found necessary to use flies bred in the laboratory from pupee gathered on the lake-shore. At first it was difficult to find these pupa., but after some time the supply was more than sufficient, as many as 7000 being brought up in one day by a few natives. These experiments go to show that a late development of trypanosomes takes place in about 5 per cent, of the flies used. This development of trypanosomes in the inside of a fly renders the fly infective and, capable of giving the disease to the animals it feeds on. The shortest time which elapsed before a fly became infective after feeding on an animal infected with sleeping sickness was eighteen days, the longest fifty-three days, and the average thirty-four days. An infected fly has been kept alive in the laboratory for seventy-five days, and remained infective during that time. It is not known how long the tsetse-fly may live under natural conditions on the lake-shore. Experiments made to test directly the duration of the infectivity of tsetse-flies show that they can retain their infectivity for at least two years after the native population has been removed from the fly area.—Dr. H. G. Chapman: The weight of precipitate obtainable in precipitin interactions.—Miss Ida F. Homfray: The absorption of gases by charcoal. The experimental portion of the work here summarised consisted in determining the volumes of gas absorbed by a known weight of charcoal, 3 grams, at definite temperatures, varying from that of liquid air to that of boiling aniline, and at pressures up to 80 cm. of mercury. The gases used were He, A, N1, CO, CH4, C2H4, CO2, O2, and mixtures of N2 and CO. After making all necessary corrections, the iso-thermals were constructed, and from them points of equal absorption were read off, the family of curves so obtained being termed the isosteric diagram. The concentration for each isostere was calculated in the form

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    Societies and Academies . Nature 83, 418–419 (1910).

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