218 Thompson yates and johnston laboratories report 
We see from these figures the striking fact that the number of deaths from 
blackwater fever is four and a half times as great as that from malaria, and that, ex- 
cluding blackwater, malaria has a small mortality. But is this the true interpretation of 
the figures, which are drawn from countries where it has always been held that, if any- 
where in the world, malaria is a deadly scourge ? It is hardly necessary to point out 
the true explanation ; that these malarial regions are so deadly because blackwater 
fever there, also prevalent, is likewise malarial. 
Again, as in the previous papers, we will allow the figures and facts to 
speak for themselves. On one of the many plausible conjectures regarding black- 
water, It may be well to make some remarks. The ' special parasite ' theory of 
blackwater was suggested to those who saw in the fact that in blackwater fever and 
Texas fever of cattle, red or black urine occurs, a proof of their identity, and the conclu- 
sion naturally followed that in blackwater fever also a parasite, allied to piroplasma 
bovis, occurred, and in pursuit of this phantasy, writers have naturally also tried to 
implicate ticks in the causation of blackwater fever. Now, it may be definitely stated 
that there is absolutely not the slightest basis of fact in the whole of this fantastic 
hypothesis. The blood and organs of blackwater patients have now been examined 
by many competent observers, and nobody has ever observed any parasite of this 
nature — parasites which in Texas fever occur in enormous numbers, and are easily 
stained and detected. To dismiss this subject, we may yet consider whether a special 
variety of malaria parasite exists, quite another matter from the view we have been 
considering, It is proved beyond doubt that blackwater is malarial. Is there a 
special malarial parasite ? This may be a difficult matter to determine, because, as 
we have seen> it is only before the onset of the hemoglobinuria that the parasites are 
constantly found. At present no evidence exists of any difference in morphology 
of the parasites found, but that a parasite is capable of displaying increased viru- 
lence under particular conditions we think there is much evidence to show. We 
cannot enter into this question further. We think that while it is possible the 
malarial parasites in blackwater may have special morphological characteristics, this 
is unlikely, and that the truer explanation is to be found in altered virulence 
depending on unknown ' climatic ' conditions, e.g., possibly the passage through a 
special species of anopheles, and upon changes in the constitution of Europeans 
not produced in temperate climes. 
LITERATURE 
1. Stephens and Christophers. Reports to the Royal Society, Series I, V. and VIII, Harrison & Sons, 
London. 
2. A.A.D. Kaiserlichen gesundheitshmte, passim. 
