112 BIOLOGY OF DEATH 



The last three o,rgaii systems, skeletal and muscular 

 system, skin and endoorinal organs, are responsible for 

 so few deaths relatively as not to be of serious moment. 



There is one general consequence of these results upon 

 which I should like to dwell a moment longer. In a broad 

 sense the efforts of public health and hygiene have been 

 directed against the affections comprised in the first two 

 items in the chart, those of the respiratory system and 

 the alimentary tract. The figures for the two five-year 

 periods in the United States, 1901-05 and 1906-10, indi- 

 cate roughly the rate of progress such measures are 

 making, Iqoking at the matter from a broad biological 

 standpoint. In reference to the respiratory system there 

 was a decline of fourteen per cent, in the death rate be- 

 tween the two periods. This is substantial. It is prac- 

 tically all accounted for in phthisis, lobar pneumonia and 

 bronchitis. For the alimentary tract the case was not 

 so good — ^indeed far worse. 



Between the two periods the death rate from this cause 

 group fell only 1.8 per cent. All the gain made in typhoid 

 fever was a great deal more than offset by diarrhoea and 

 enteritis (under two), congenital debility and cancer. 

 Child welfare, both prenatal and postnatal, seems by long 

 odds the most hopeful direction in which public health 

 activities can expect, at the present time, substantially to 

 reduce the general death rate. This is a matter funda- 

 mentally of education. 



SPECIFIC DEATH BATES BIOLOGICALLY CLASSIFIED 



Up to this point in our discussions we have been deal- 

 ing with crude death rates, uncorrected for the age and 

 sex distributions of the populations concerned. It is, 

 of course, a well known fact that differences in age and 



