labourers provide the largest percentage of long lives. _Improved Conditions of Life._--There is good evidence that the average expectation of life has improved in this country during the period that increasing attention has been paid to sanitation. This is shown by the tables of the Registrar-General. For most of the following information I am indebted to Dr. T. H. C. Stevenson of the General Register Office, Somerset House. In 1838–54 the expectation of males at birth in England and Wales was 39·91 years, in 1901–10 the male and female expectations at birth were 48·53 and 52·38 years respectively, and the latest available expectations at birth (English Life, Table No. 8, Supplement to the Seventy-fifth Annual Report of the Registrar-General, Cd. 7512) are 51·6 for males and 55·35 years for females. But the expectation is probably considerably more now, as the death rates have fallen appreciably since 1910–12. The Prussian male expectation of life at birth has increased from 35·38 years in 1867–77 to 46·43 in 1906–10;[60] and the Swedish[61] expectation of life at birth from 39·5 years in males and 43·6 years in females in 1816–40 to 54·5 and 57 years respectively in 1901–10. In North America[62] there has been a fall in the death rate in every age group in 1920 as compared with 1910. The increased expectation of life has been especially prominent in early and adult life. Examination of the Registrar-General’s census returns from 1851 to 1911 show that although there were more persons per million living between the ages of 55 and 75 there were less above the age of 75 at the end than at the beginning of this 60-years’ period. It has been suggested that the increased survival in the earlier period of old age is due to the saving of life in infancy and that, as these lives are not prolonged above the age of 75 or so, the diminished proportion of persons living to become octogenarians is explained (H. Weber).