26
defective state of their teeth, have been least able to utilize to the full such nutritive
support as is contained in unhusked rice, and so would be weakened and rendered
(perhaps) more liable to invasion by spirilloids. Sex influence has been marked in
the 3rd Native Infantry at Tonghoo, there having been 39 cases in females against
15 in males. In Rangoon, however, mares and geldings have been affected in about
equal proportions, and several stallions have died. Evidently sex has, as a rule,
but little to do with development of relapsing fever in mules. Color, too, will not
require much special notice. It. is certain that in outbreaks of this disorder but
few grays are left unaffected. This is difficult to explain except by the known
laxity of fibre in animals of this color as compared with darker ones, also their
admitted special liability to lymphatic and asthenic disorders. It is evident that
no special color secures exemption from relapsing fever. In the Somersetshire
Regiment I find a loss of 16 grays and 1 white against 23 browns and 5 bays—a
very large proportion, when we consider the relative frequency of the lighter and
darker colors. In the 3rd Native Infantry " red" and "black" mules and whites
suffered most and about in the same proportion (25 percent of total fatalities),
but everywhere mules of almost all the numerous and varied colors presented by
this hybrid race died. The preponderance of fatalities among grays seems to be well
established. Physique.—The influence of natural habit of body is obscured by the fact
that the majority of patients when first observed to be affected are in poor condition as
a result of undiagnosed disease. But one thing is very certain, and it materially assisted
in leading to the conclusion that this disease is not merely pernicious anæmia, namely,
that animals with much superfluous fat, plentiful reserves of nutriment, succumb espe-
cially to the acute form of the disorder; indeed it almost seems as if, like Anthrax, it
carries off all the best mules, and that apparent strength and vigour of constitution
invite attacks by the spirilloid. It may be that animals which die from the disorder
when fat are not really "in condition," that, although looking comfortable and well,
they are not in that state best rendering them fit for real hard work, and, from the
debilitating effects of fatty heart and liver, cannot resist the severity of the fever.
21. It is now necessary that we utilize such exact records as are available with a
view to the examination of possible causes in their relations to the outbreaks as deter-
mining influences, and we shall thus arrive at some specially significant facts about
the attacks which will show how certain influences have been particularly operative
and are to be avoided in the future with a view to prevention. Work may by its exces-
sive or defective amount predispose to the disease, severity of work must lessen the
animal's constitutional resisting powers, such as, for instance, when a mule, after an
exhausting day's work, has to rest during the night in a malarious place; deficiency of
work has somewhat the same result by lessening the general tone of the animal's system.
Also the nature of work may be such as to bring the animal within the sphere of
disease influence. Much stress has, as we have seen, been laid on the effects of puckali
work, because it was observed that almost all the large mules used for this purpose in
the Somersetshire Regiment died. But these mules were the most predisposed as being
large, horse-like, overworked, probably (as being at special work) irregularly fed,
excessively exposed to cold and moisture, and almost certain to drink from the tanks
from which they were bringing water for fire-engine, washing, and other purposes
although it was forbidden to be drunk by mules or men. In spite of the strictest
injunctions and, in some cases of neglect which were detected, severe punishment, it
would obviously be impossible for a driver busy in filling a puckal to prevent his mule
taking an occasional mouthful from water in which it was standing. When it is con-
sidered that for a long time the mules were working with camel puckals, each when
full weighing 195 lb., and that the 390 lb. thus placed on the animal had to be carried
up the steep path leading from the tanks to the men's lines for many hours in the day
and that the driver would not be likely to give himself more work than he could help
by only half filling these puckals each journey so as to give only the regulation load,
we must conclude that hard work and exposure especially predisposed the puckal mules,
although the theory of water as a cause derives a certain amount of support from the
fact of these animals suffering most. In the supply depôt in 1883-84, when the
disease prevailed so much among the mules in general, none of them were used for
puckal work except one which remained unaffected. In Tonghoo also the influence