11
account for the secondary infection of the inhabitants of these better
class houses.
It is immaterial from our present point of view what exactly are
the conditions in Bombay as regards anopheles ; what we wish to em-
phasize is the real nature of the present epidemic. It may not be with
out interest, however, to point out that with the new insight we have
indicated such an epidemic could have been foretold and measures
could have been taken to prevent the formation of the malarial focus
with much less difficulty than will now be found in controlling the
conflagration to which it has given rise.
We are informed that at first labour was housed on the dock site,
but that latterly it had almost all been accommodated in distant
portions of Bombay. If so, we should expect the epidemic to invade
new areas during the next few years, and quite possibly to extend
to large portions of the environs.
Hong Kong; Wilhelmshaven and many instances of virulent
outbreaks of malaria associated with works could easily be given.
It is reasonable to believe after what we have said that the real
determining factor in all is that of tropical aggregation of labour.
But it must not be imagined that the conditions we have been
describing and the effects that we have indicated as resulting from
them are to be seen only on a small scale and confined within narrow
area, or that they occur only occasionally in the course of years and
constitute a mere unimportant item in the epidemiology of mala-
ria. We have seen that in the case of the Duars the inauguration
and extension of an industry has produced throughout a whole district,
many hundred square miles in area, an extraordinary condition of
exalted malarial endemicity, characterised by the occurrence of Black-
water Fever among Europeans and widespread anmia among the
natives, a condition we shall describe in relation to the malaria of a
population as one of HYPER-ENDEMICITY.
Under similar circumstances the Darjeeling terai attained some
years ago an unenviable reputation of a like nature ; and Assam, cspe-
cially in past years before legislative interference enforced the adop-
B 2