But, however this may be, the grounds upon which I base my belief that "chill" in the one case, and "heat" in the other, is the most common exciting cause of these maladies, respectively, are furnished by the fact that malarious fevers are found to prevail with a periodicity corresponding with that of the annual seasons of greatest change in the weather elements, namely, the spring and autumn, and moreover, with a periodicity corresponding, at least in the Punjab, for which province the statistics have been tabulated, with the triennial cycles of rainfall -- a peculiarity in which they coincide with cholera -- whilst sun-fever or sunstroke is found to prevail with a periodicity corresponding with the season of highest temperature.