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     We can therefore eliminate from among the possible causes of Black-water
Fever most chemico-toxic substances; even did the clinical evidence not enable
us to do so.

     The only substance that it is really necessary to consider in this relation is
quinine, which has often been credited as the cause of Black-water Fever.

     The hæmolytic effect of quinine hydrochloride has been shown by Stephens
and Christophers, who found that it extended to four or five dilutions of a saturated
aqueous solution. We have repeated and confirmed this Obs rvation, and have
made other experiments both with the hydrochloride of quinine and the pure
alkaloid.

     The latter is extremely insoluble but suspensions in .9 per cent. salt solution
appear to exert no hæmolytic effect upon canine or human red cells.

     With regard to the action of saturated solution of quinine hydrochloride the
following procedure was adopted. A saturated solution was first prepared
containing approximately 3 per cent. (Attfield (86) states that this salt is soluble
in 34 parts of water.) This saturated solution was then made up by the addition
of sodium chloride until it contained .9 per cent.of the latter salt.

     On the addition of 200 c.ms. of this solution to suspensions of 10 c.ms, of
human blood in ½ c.c. .9 per cent, salt solution nearly complete hæmolysis took
place, both in the case of a normal and a Black-water blood.

     But when in the case of both normal and Black-water blood suspensions, the
addition of 150 c.ms. of (a) normal and (b) Black-water serum was made prior to that
of the quinine solution, a reaction occurred accompanied with the precipitation of
the quinine as a fine white powder. Prolonged centrifuging failed to entirely clear
the supernatant fluid which remained slightly clouded but showed no trace of
hæmolysis. In what form quinine may exist in the circulating blood we do not
know; but Stephens and Christophers found that cinchonised serum taken from a
healthy subject shortly after the administration of 2 grms. of quinine when sub-
jective symptoms were present, exerted no hæmolytic action upon the blood of a
Black-water Fever case. A consideration of these facts, together with those already
referred to in Part I, seems to exclude the action of quinine in itself as being the
cause of the lysæmia of Black-water Fever.

     The indirect action exerted by this substance in the production of this con-
dition must be left for future consideration.

227 H. D.

2N