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XXI] coccus can live for a long time in water, in dust, or on the clothes of patients, and that it is not killed by cold or desiccation. Moreover, it is now known that it is excreted in the urine, and that it occurs in great abundance in the milk and urine of apparently healthy goats (50 per cent.) and cows, and in the urine of apparently healthy men. It is also found in dogs (9 per cent.), sheep, and horses. These facts account in part for the great frequency and dissemination of the disease in such insanitary places as Malta, to which place they specially refer. Influence of age and residence.— The most susceptible age is between the sixth and the thirtieth year. Length of residence does not influence susceptibility. In Malta the natives suffer as well as visitors.

Influence of season.— In Malta and other places where the disease is endemic this fever occasionally assumes an epidemic character. The period of its greatest prevalence in Malta is the season of lowest rainfall, embracing June, July, August, and September; differing in this respect from typhoid, which, in that island, is more prevalent during the succeeding months. It is not confined absolutely to the summer months ; cases occur all the year round.

Local causes.— The disease tends to occur in particular towns or villages, in particular houses, barracks, hospitals, and rooms, and in particular ships, manifestly originating in limited foci of infection. The weight of evidence was regarded by some as pointing to its diffusion by air currents, and not by food or water. There is no absolute certainty on these points. Evidence is rapidly accumulating to show that milk is the most important medium.

Formerly it was supposed that in Malta this fever was linked to the immediate neighbourhood of the seashore, and that the sewage-laden, tideless condition of the harbour at Valetta was somehow responsible for its prevalence there. Zammit has shown, however, that the disease occurs all over the island, and that in some instances it is more prevalent in certain inland and relatively sanitary villages than