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APPENDIX III.
Apparatus used for the Capture and Development of Larvæ.
The Salsette enquiry afforded a pretty extended opportunity for testing the relative
usefulness of different forms of apparatus that have been used or suggested for use else-
where., and finding out the best way of using those that were found to be really practical.
The following were found the best to use :—
DR. BENTLEY'S WELL-NET.—This is described in Dr. Bentley's Report on
Malaria in Bombay. A substitute, which does not fold up like the original, was obtained
for the Salsette investigation through the Malaria Assistant to the Health Officer, Bombay
Municipality, from a Borah named Hassan Ali Abdul Ali. The well-net is absolutely
indispensable, and even with its use larvæ will be missed if Dr. Bentley's directions about
inverting the net and washing it are not followed in every case.
BUCKET,—This is needed to bring up some of the water of each well to wash the
larvæ out of the net. If the rest of the kit is to be carried in it the bucket should be as
large as possible ; otherwise, the smaller it is the better.
ENAMELLED FRYING-PAN.—This was introduced by Dr. Bentley merely to
wash the net, but in the Salsette enquiry it proved to be by far the most useful vessel for
catching larvæ in tanks and streams, as the width of the sweep one can give with it
enables such a large surface of water to be examined at a time, and as it can stand rough
usage so well, when the bottom of a stream is being examined.
LONG ENAMELLED SPOON.—This is chiefly of use in skimming the larva from
the water in the frying-pan, but it is also useful in examining hoof-prints and other small
hollows containing water.
ENAMELLED MUG.—The two latter articles suffice for nearly every open place
but a mug is needed for work in rice-fields and places- where long grass stands in water.
QUININE BOTTLE.—Both for carrying in the field and for keeping the larvæ
in afterwards to hatch out, the most useful bottles to use are ounce-of-quinine bottles,
which are obtainable easily in the bazaar. These are cylindrical bottles of seven fluid
ounce capacity, and the most suitable ones are those which have a broad flange on the lip.
Each should be fitted with a string round the neck to which to fix another loop of string,
like the handle of a basket, to carry the bottle by. The cap of the bottle is best made of a
little square of coarse dangri or khadi cloth, tied to the string on the neck by a thread a
couple of inches long. This cloth is of open texture, and allows free access of air. To
the upper surface of the cap, near one edge, should be sewn a loop of silk elastic. If the
cap is laid on the mouth of the bottle it can be fixed on in a second by laying the forefinger
of the left hand, which holds the bottle, on the insertion of the loop, against the neck, and
slipping the loop down over the mouth with the right hand. The bottles are carried in the
field with the 'caps hanging down. Each is capped as soon as it is filled, without the aid
of any string. A good rule to make is that, once it is capped, no bottle is to be opened,
except by the Malaria Officer himself.
Each bottle has a label, bearing simply a serial number, in English and in the
vernacular, which is written on it when the day's batch of bottles is being issued, and
which corresponds with a number in the register. The bottles are carried in a wooden box
or tray with compartments, which has a handle rising from the middle compartment, and
as each is filled and capped the searcher enters the number in the margin of his note-book,
and opposite this makes a note of the kind of collection of water the larvse were taken
from, and the village survey number, or other means of identification of the place. At the
end of the morning's or evening's search the bottles are returned to the laboratory, and
the notes copied from the searcher's note-book into the register, opposite the serial
numbers. If carbons are used with the note-books individual searchers need not attend
the laboratory ; they tear out the pages and send them in with the bottles. The bottles
are examined as soon as the Malaria Officer has time to attend to them and then write up
his part of the register. In Salsette the register was kept somewhat in the following
fashion :—