The experiment was started on 28th December, 1950 and con- tinued to the time of writing. The humidity was rather high (70-90%) and the temperature averaged about 65'.
The cells were examined daily, but although large numbers of Musca vicina were seen on the surface of nightsoil in the control cell, and of dead ones on the treated cells, no signs of larval breeding were found until the 10th January (ie. the 14th day). This breeding was entirely confined to the control pits in each station, but no larvæ were found in the treated pits at either station.
A subsequent series of experiments using Gammexane in dilutions of 1/800, 1/1,600 and 1/3,200 have also been completely inhibitory to all forma fly larval breeding in nightsoil up to the time of writing. These experiments will be continued under summer conditicos of temperature, humidity, and rain fall.
The present cost of nightsoil is 50 cents per bucket of 50 lbs. Thus, based on the minimum effective dilution of 1/3,200 is. † oz. of Gammexane to 50 lbs. of nightsoil, the cost of prevention is only Cents H.K. & per bucket.
ANNEXURE O.
J. B. MACKIE,
Malariologist.
ANNUAL REPORT OF THE PALHOLOGICAL INSTITUTE
INTRODUCTORY.
Further expansion of routine work, shown graphically here. under, was the most significant feature of the year's activities, apparently not caused by any further increase in the population, but due partly to the institution of antenatal Kahn tests for all maternity cases, which in effect practically doubled the numbers of such tests performed and partly to a general expansion of work of the Kowloon branch, which dealt with 10,000 more specimens than in the previous year.
Vaccine production, more directly related to the size of the popu̟- lation, has become a continuous struggle to produce what is required in premises which were designed for a mere fraction of the present output.
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On one unfortunate occasion, when two refrigerators happened to break down simultaneously, our lapinised strain of rinderpest virus died, but the importation of a new strain from Bangkok soon put matters right.
Store room facilities at the Institute were amplified by the con- version of a room adjoining the yard, and the installation of shelves and bars to the windows.
Experiments carried out last year on nightsoil for use as a fertilizer having shown that a satisfactory and economical method of rendering the material safe within a short period, as regards ova of helminths, has yet to be discovered, this year an investigation was com- menced to see whether vegetables grown under treatment with human nightsoil-a system common throughout China-were in fact infective by the time they appeared for sale in wholesale markets. So far only a few leaf and root specimens have been examined, but the fact that fæcal B. coli was isolated from the fourth sample of carrot, whilst the second specimen of cabbage contained, in addition to fæcal B. coli, ova of ascaris, ankylostoma, clonorchis, and trichuris, is perhaps sufficiently significant.
Other items of interest included the discovery of a typhoid carrier at the Sai Ying Pun Hospital and a bacillary dysentery carrier at the Mental Hospital; two instances of Bact. paratyphosum C infection; the establishment of Pasteurella aviseptica as the cause of an outbreak of fowl cholera in a local dairy; and the isolation of B. pyogenes from the liver of a cow which died of pyæmia.
The following additions were made to the library:
Textbook of Virology
La Rage
Rhodes and Van Rooyen.
Remlinger & Bailly.
Clayden.
Practical Section Cutting & Staining
Malaria Diagnosis
Field.
Staff changes-In May Mr. C. Y. Chan was engaged as Labora- tory Assistant on probation; Dr. R. E. Alvares returned to duty and Dr. W. T. Liu left the service for health reasons in June; Mr. A. E. P. Grimmo, Senior Laboratory Technician, returned from home leave in October; and Dresser Lau Lai Sang was transferred temporarily to the Institute staff in December to help in the Kahn test.
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