374 



BIOLOGY AND HUMAN LIFE 



produce. One of the best single tests of good homes in a com- 

 munity is found in the infant death rate (see page 358). It 

 is usually expressed as the number of infant deaths per thou- 

 sand births in a year. Thus, an infant death rate of 112 means 

 that in one year that number of children under one year of age 

 died for every thousand children born during the year. 



The wide variation in the infant death rates of different com- 

 munities is shown in the following table, which is selected to 

 show the best records and the worst records for one year, 1923 : 



INFANT MORTALITY RATES FOR THE YEAR 1923 IN TWENTY 



SELECTED AMERICAN CITIES 



(Total deaths under one year of age per 1000 births) 



These figures show that out of a given number of babies born 

 in a certain time more than twice as many died during the first 

 year in one city as in another city. Moreover, similar variations 

 are found between the death rates in one district and the death 

 rates in other districts of the same city. A baby, one might say, 

 has a better chance of seeing his first birthday if he is born in 

 one part of the city than he would have if born in a certain other 

 part of the city. Now what is it that endangers babies' lives in 

 one case or protects them in the other? 



The best information that we now have on the subject shows 

 that to a very great degree the children that die in infancy could 

 be saved, because the excessive deaths result from conditions 



