M 136
in (B) in some collections made in the cold weather, A. minimus larvae were numerous. A few adults of A. fluviatilis were obtained from the larvae and pupae collected from (B).
88. Monthly collections were also made from two streams (D) and (E) in the portions lying between Island and Victoria Roads. Stream (D) runs alongside Sassoon Road, stream (E) runs parallel to (D) but is further south.
B
89. In January 322 A. maculatus, 89 A. minimus larvae were collected from (D), the first occasion in the course of several surveys in which such a large number of A. minimus were obtained from this stream. In recent years a considerable amount of filling has been done in the angle between Island Road and Sassoon Road, the face of the filling is supported by a stone wall containing numerous weep holes, from one of these, water which feeds the stream issues. Later in the year a dam was placed across the stream and the pool thus formed used for bathing in the hot weather, and for washing in the cold season.
90. There are cattle byres on the banks, the drainage from which finds its way into a concrete sump which overflows into a system of ditches but does not directly pollute the stream. Only 10 more A. minimus were collected during the rest of the year, in the last quarter. Altogether 1,204 A. maculatus and 99 A. minimus were found in this portion of D.
91. There is a dam across stream (E) a little below Victoria Road, farther down a manure dump drains directly into the stream. There are also cattle byres along the bank as in the case of stream (D). A total of 1,877 A. maculatus and 7 A. minimus larvae were obtained. No A. minimus were found in the May-September period.
92. Chemical analysis of the water and the determination of its pH value, may perhaps help to explain why A. minimus larvae is present in some streams and absent from others. The effect of soap pollution upon streams requires investigation in regard to the presence or absence of A. minimus.
Felix Villas (Pokfulam).
93. Investigations were made in this neighbourhood owing to complaint of the occurrence of a case of malaria in November. Thick blood films were obtained from 62 servants. Out of 21 who resided on Mount Davis Road, 1 was found positive; out of 41 who resided at Felix Villas 1 was positive. No parasites could be obtained subsequently in the examination of a thin film obtained from the former but in a thin film obtained from the latter, benign tertian parasites were found.