In 1875 measles first reached the inhabitants of the Fiji Islands. The disease was introduced by the King of the Fiji Islanders and his escort, upon their return from New South Wales. The entire population of the islands was estimated at 150,000 and it is officially stated that there were 40,000 deaths from measles in the ensuing period. In certain islands and villages where more exact information was secured, it was found that from twenty-seven to twenty-eight per cent. of the people died. Panic, insanitary conditions and ignorance of how to care for the sick resulted in this high mortality. V. C. Vaughan has remarked that when measles is introduced into a population with a susceptibility of 100 per cent. “it strikes down so many at practically the same time that adequate care for the sick is impossible.” The rapidity with which the population is invaded is practically as great as it is during influenza epidemics. It is the opinion of the author that the phenomenon which contributes chiefly to the occurrence of influenza in epidemics and pandemics, and which causes the characteristic curves of a primary influenza wave, is the absence of any permanent immunity. We have shown in our discussion that no immunity is proven to exist after a year and a half or two years at the most. Measles occurring in a non-immune population spreads through that population with the same high rate as does the influenza. In Charts XXVIII and XXIX we find the curves of incidence of measles in certain of the United States Army camps in the fall and winter of 1917–18. The simplest curve is that for Camp Wheeler. Here the type is similar to that found in the primary wave of influenza. There is a quasi-symmetrical evolution and the concentration is closely grouped around the maximum. The total duration of the epidemic is short, not being much over eight weeks. The troops at this camp were predominantly rural. The disease starting in this group of relatively non-immunes spread rapidly until presumably all susceptible material was exhausted. Compare Camp Wheeler with those camps where the population was chiefly urban. Here the wave is of longer duration, is not as high, the increase is slower, the decrease is more gradual and the concentration is not grouped so closely about the maximum. In the case of the other camps with chiefly rural population, the curve is not as simple as is the case with Camp Wheeler, and there are at times secondary curves as in the case of Camp Bowie, but the essential similarity to the curve at Camp Wheeler and the difference from the curves at Devens, Dix, Custer and Grant is striking. It may be that the double waves are explained by acquisition of new bodies of troops, by the introduction of new susceptible material. On this question we have no exact information. CHART XXVIII. [Illustration: Respiratory Disease at Army Camps] CHART XXIX.