56
Paras. 30 & 31
mosquito, from itself. We do not know whether the laws of proteosoma apply
entirely to human malaria, but if they do, as is extremely probable, the same
thing will occur to human beings.
At all events, it is clear that poor people living in the humblest of houses
in pestiferous surroundings are just as likely to receive infection on many days
in succession as on one day ; if the poison be present there is no reason why its
action should be limited to one occasion. A European coming to such a spot,
say for one day, contracts only a single infection ; the inhabitant a series of
infections. The former, mildly invaded in the first place, breaks the force of
the invasion further by quinine ; the latter has nothing to rely on but the
reactionary vigour of his own constitution, which moreover must deal with a
much more grave condition of affairs. In the former the natural forces which
make for immunity, strongly aided by medication, are scarcely called upon to
exert themselves at all ; in the latter they must put forth their full strength,
and that at once, in order to avert the great danger which threatens. In the
first case, the parasites find little natural impediment to their indefinite propaga-
tion ; when, on the occasion of a chill or of the temporary remission of quinine,
they multiply again sufficiently to cause a slight attack of fever, the drug is
resumed and their numbers immediately vastly reduced ; and this state of
things continues for years, perhaps with little inconvenience to the patient.
In the second case, however, they are confronted very soon by a violent natural
antagonism which they themselves have roused ; which, if they do not succeed
in overcoming it at once, gains vigour with their continuance and finally
exterminates them.
Add to the second case the terrible secondary destructive effect on the
organs produced by the first great rush of the invasion and we have elaborated
the antithesis suggested in paragraph 26 between the continued paludism of
Europeans and of Natives of tropical malarious localities.
In the first, we have the parasitic pervasion of the system continuing for
years, now increasing now diminishing, attended by alternating periods of quies-
cence and of the conflagration of the typical fever, and producing only a
moderate secondary affection of the organs.
In the second, we have the first inordinate rush of parasitism, followed, if
not by the death of the patient, then by the speedy extinction of the invaders,
and leaving behind it as a residuum an early and often severe affection of the
organs.
Of course, such an antithesis can only be accepted in the rough and is
often obscured by other considerations. The European, for instance, is generally
more susceptible to the toxic effects of the parasites than the Native is, so that
he seems to suffer more with less occasion. But a little reflection will suffice
to disentangle these issues.
31. Influence of Difference of Species in the Parasties.—We now
emerge on what is perhaps more solid ground.
Since the investigations of Golgi in 1885, it has generally been accepted
that there are at least three different varieties or species of the parasites of
malaria. They differ from each other morphologically and in their effects on
the host ; and these differences have been carefully mapped out by a host of
observers in most malarious countries—until we can now distinguish one species
from another almost at a glance. What effect may this difference of species
have on the questions under discussion ?
It is necessary first to consider that a great authority—Laveran himself—
while admitting the morphological differences, refuses to admit that they con-
stitute difference of species. He thinks [25, p. 84] that difference of climate or
temperature will account for the morphological differences met with ; and Mar-
choux, in his recent study of paludism in Senegal [22], supports this view.
Laveran implies however, (p. 81), that if the various forms could be found exclu-
sively, each at a separate spot in the same climate and at the same season, this
would suffice to establish difference of species.
My own conviction, based on my experiences in "India, is that this is exactly
what occurs. In Secunderabad in the Deccan I made a very long study of
fever during the rains of 1895 and of 1897, occurring in my regiment stationed
in the locality called Begumpet. Though I found the parasites in some
hundreds of cases, and though I observed scores of cases infected by the tertian