The immense economic significance of the fact that among men nine out of every ten deaths from phthisis occur between the ages of 15 and 65. Dr. T. E. Hayward calculated by the life-table method what would be the effect of totally abolishing phthisis from the death-returns of England and Wales for the decade 1891-1900. It will be observed that the number of survivors from infancy to the age of 15 out of a given number born is not materially increased by the elimination of phthisis. From this point onwards the elimination of this disease would steadily increase the number of survivors. Judging by the experience of 1891-1900 in England and Wales, the abolition of phthisis would increase the expectation of life of every male aged 15 years by 2.8 years, and of every male aged 25 years by 2.3 years.