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hardly, if at all, amenable to quinine, it is quite exceptional to find in any hospital
a case of this nature which is not being treated more or less vigorously with
this drug, so that to prove definitely the connection between such cases and
malaria becomes a difficult matter.

IV.—The investigation of malaria among the general population.

         It is certain that an examination of the statistics of admissions into hos-
pitals for malaria gives us no real indication of the amount of malaria prevailing
in a district at the time, and from a study of hospital cases we can learn nothing
regarding the conditions under which the disease prevails. The method of inves-
tigation by which, above all others, the most valuable advances in our knowledge
of malaria are likely to be made, is that of the investigation of the disease as it
occurs among the general population of a place or district. The study of cases
in hospitals and a detailed study of the structure of parasites is of little or no
importance compared to a comparative study of the conditions under which
malaria prevails in different places, and as this is a method of investigation
which has received little attention in India up to the present, special importance
should be attached to it.

        An outline of the principles upon which such investigations have been
carried out by us is as follows:—

          Having selected a village or series of villages in any district for in-
vestigation, our first object is to find out, as accurately as possible, the
amount of malaria and the liability to infection existing at the time of the
investigation.

         We have found in India, as was previously found in Africa by Koch and by
Stephens and Christophers, that in any place which is more or less malarious, a
certain number of the young children will have malaria parasites in their blood;
and the percentage of young children so affected affords the most accurate test
of the amount of malaria and the liability to infection existing in the place
under examination.

         The term "Endemic Index" has been given to this percentage of infected
children, and the first thing to do on arriving at a village is to determine this
endemic index.

         For this purpose films of blood must be taken from at least thirty or forty
children, none of whom should be over ten years of age. As may be imagined,
this is often a difficult matter in Indian towns and villages, but with tact and
patience it can be done, and except in one or two villages in Bengal we have
never failed to get the required number.

          The blood films should be taken by the method previously described, and
any other method is practically impossible under the circumstances. At the
same time as the films are being taken, the spleen of each child may be