+Earlier Estimates of the Prevalence of Syphilis.+--It is generally conceded that there is more syphilis among men than women, although it should not be forgotten that low figures in women may be due to some extent to the milder and less outspoken course of the disease in them. Five times more syphilis in men than women conservatively summarizes our present conceptions. The importance of distinguishing between syphilis among the sick and among the well is often overlooked. For example, Landouzy, in the Laennec clinic in Paris, estimated recently that in the patients of this clinic, which deals with general medicine, 15 to 18 per cent of the women and 21 to 28 per cent of the men had syphilis. It is fair to presume, then, that such a percentage would be rather high for the general run of every-day people. This accords with the estimates, based on large experience, of such men as Lenoir and Fournier, that 13 to 15 per cent of all adult males in Paris have syphilis. Erb estimated 12 per cent for Berlin, and other estimates give 12 per cent for London. Collie's survey of British working men gives 9.2 per cent in those who, in spite of having passed a general health examination, showed the disease by a blood test. A large body of figures, covering thirty years, and dating back beyond the time when the most sensitive tests of the disease came into use, gives about 8 per cent of more than a million patients in the United States Public Health and Marine Hospital Service as having syphilis. It should be recalled that this includes essentially active rather than quiescent cases, and is therefore probably too low.