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discarded or where the water was not renewed often enough, larva; were present 
in abundance. In the poorer houses tins were often found containing a strong 
solution of wood ashes for washing purposes ; in these larvae could usually be found. 
The Wooden Vats. — Number examined, 489. I found larvae present in a 
large number of the vats. It is often, however, difficult to find them at first. 
The top of the vat has to be reached with a ladder and the lid disturbed, the 
result is that the larva; disappear, and the impression is given that there are no 
larvae present. In these cases I have sometimes found them by drawing off the 
water by the tap at the bottom of the vat. They probably all contain larvae, but 
not in such abundance in proportion to size as the barrels. 
The Iron Tanks. — Number examined, 271. Owing to the smallness of the 
lid it was difficult to make a thorough examination of these receptacles. Larvae 
were present in many, but not in such abundance as in the wooden vats, the 
iron rust in the water may have some effect, but in all probability only very slight. 
The Wells. — Number examined, 91. The well water is within a few inches 
of the surface of the sodden ground, and is as a rule dirty and often decomposing 
from the presence of vegetable and animal matter. In a large number larvae were 
present, in a few they were absent, which I attributed to the effect of recent oiling. 
The Effect of Oiling the Receptacles. — In the examination of this large 
series of receptacles I could not detect an appreciable diminution of larvae from 
the oiling, which had come into force since June, due, no doubt, to the fact that 
the frequent rain washes the oil out in those cases where it has been used ; 
moreover, it was obvious that it wais not applied often enough, or in sufficient 
quantity, atnd then only in a certain number of receptacles. 
2. — Species of Larvae Present in the Water Receptacles. 
In all clear-water receptacles the larvae of the Stegomyia fasciata were far in 
excess of all other kinds. On approaching the barrels silently, the characteristi- 
cally banded mosquito could usually be found sheltering on the staves. The 
larvae could also often be distinguished, but in the majority of cases samples of 
the larvae were taken to the laboratory to develop, and with few exceptions they 
yielded the characteristic mosquitoes. Culicidae were not numerous in the clear- 
water receptacles, they made their appearance in large numbers only when the 
water was very dirty and decomposing. 
The following figures show the proportion of the Stegomyia in the 
receptacles. In the 500 lots examined by Mr. Burchell and mysell 1 found 
the Stegomyia present as follows ; — 
In first 100 lots, 19 times. 
In second 100 lots, 44 times. 
In third 100 lots, 38 times. 
In fourth 100 lots, 26 times. 
In fifth 100 lots, 35 times. 
or in the 500 lots in the proportion of 3-34 per cent. 
In the 164 lots examined by Dr. Heusner the Stegomyia was found 82 
times, or in 50 per cent., and in the 172 lots examined by Dr. Harrison, 
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