374 



HUMAN BIOLOGY 



Table viii 



measles, scarlet fever, diphtheria and croup: death rates per 100,000 

 population, u. s. registration area 



than in rural regions. The mortality rates serve as a prob- 

 able rehable index of the degree of difference. In 19 lo the 

 urban rate from syphihs was 7.3, the rural 3.0, while in 

 1920 these were 11.9 and 6.0 respectively. Similarly for 

 gonococcus infection the urban rate was 0.5, the rural 

 o.i in 1910, and 1.2 and 0.4 respectively in 1920. Some of 

 the difference may be due to the greater proportion of 

 persons of the earher decades of life in the cities. 



All differences in the mortahty and morbidity of city 

 and rural populations cannot be explained on the bases of 

 risks of infection, nor yet by the alternations from optimum 

 in the factors of physical environment. The marked and 

 consistently higher death rates from diabetes and appen- 

 dicitis in cities are in all probabihty related to the manner 

 of Hfe, with superalimentation and the decreasing necessity 

 for bodily exertion in the ordinary conduct of life as the 

 major causes. 



While there is an obvious tendency towards a similarity 

 in the physical equipment of life and labor of the country 

 and city households, there remains the fundamental differ- 

 ence between the closed places of work and the nature of 

 work under unfavorable atmospheric conditions in cities, 

 and the outdoor occupations of the rural family which 

 more nearly approach a favorable biological opportunity 

 for both survival and development. 



There is no controlled mass of information upon the 

 relative frequency of mental and nervous diseases among 

 city and rural populations except in the matter of such 

 advanced, serious or terminal conditions as are of necessity 



