PART II.

BLACK-WATER FEVER MALARIAL IN ORIGIN.

Chapter I.

BLACK-WATER FEVER CONDITIONS.

   A glance at a rainfall map of India shows at once two areas where the rain-
fall far exceeds that over the rest of India. One is a narrow strip along the
Western Ghauts and West Coast. The other is situated along the base of the
Eastern Himalayas and the Garo and Kassia Hills, where these ranges intercept
the moisture-laden monsoon currents from the Bay of Bengal; within its limits
are included the small districts of the Darjeeling Terai, the more important
tract known as the Duars and the still more important and extensive Province
of Assam.

   It is this latter area with which, we are entirely concerned, since it will be
found to correspond to an area from which cases of Black-water Fever have
been frequently reported. In 1898 Powell (26) records the occurrence of
Black-water Fever in Assam, reporting eleven cases which had come under
his observation in North Cachar. Shortly afterwards Seal (27) gave particu-
lars of a case seen by him in Sylhet, another district of Assam, and six
other cases in the Darjeeling Terai. In 1900 the Rev. G. M. Crozier, M.D. (51),
described two other cases from Cachar; and a little later Stephens and Christo-
phers noted in their report to the Royal Society that the disease was frequent in
the Duars, and also referred to a letter received by them from an Assam planter
mentioning that it had been recognised for a number of years in Nowgong.

   Since then the Duars has gained a notoriety far above Assam as a Black.
water Fever country. But cases have come under the personal observation of
one of us in the Darrang district (Assam), while particulars of others have been
sent to us from various parts of the Province.

   To what conditions does the district under discussion owe the occurrence
of Black-water Fever; and why is the Duars especially the seat of the disease ?

OPENING UP OF THE SOIL.

   The belief that severe malaria is often the result of opening up the soil has
long been held. To explain this, it has been customary to note that pools are
generally formed suitable for anopheles to breed in, and that malaria is the

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227 H. D.