23
Society's Commission to be more or less uniformly high. We have ex-
tended these observations to a considerable proportion of the total gar-
dens and have found that the amount of infection noted can be stated to
vary very little throughout the Duars. In a large number of estimations
involving the examination of many hundred of children we have only
twice found the endemic index below 50 per cent., and in the vast major-
ity of cases it approximated very closely to 100 per cent. The spleen-
rate has never been less than the endemic index. These points will be
demonstrated by the tabular statements of our results given in Ap-
pendix I. Specially noteworthy is the maintenance of this high rate
of infection through some seven months of the dry season and its
presence on a number of gardens so situated as to appear extremely
unfavourable to the existence of even a moderate amount of malaria.
Race appears to play but little part in influencing the prevalence
of infection, though some races appear to be more profoundly affected
by the disease than other. In several instances where we have examined
the children of hill and plains people living on the same garden under
similar conditions, but with the two races widely separated, we have
found the rate of infection and of enlarged spleen to be practically the
same in each case. As a general rule, however, more actual sickness
due to this disease is seen among the hill people than, for example,
among natives of the Ranchee and Hazaribagh districts.
Adult malaria.-Malarial infection in the Duars is not confined to
the children, but affects profoundly a considerable proportion of the
adults. This is especially so in the case of new coolies, most of whom
come from comparatively non-malarious districts and are quite different-
ly circumstanced as regards malaria to indigenous adults in a malari-
ous country, who have been immunised to malaria during childhood.
The extent to which adult in the Duars suffer from the disease will be
gathered from facts given in the chapter on" Sickness in the Duars."
VARIETIES OF THE PARASITE.
All three forms of the parasite, quartan, simple tertian and malig-
nant tertian, are almost equally common, though simple tertian infec-
tions slightly preponderate.