126 



AGE-INCIDENCE: otf CAUSES 



INFANT MORTALITY 



but not to fit seasonal curves such as we are making from Neu- 

 mann's figures. Pearson's three factors are 391, 131, and 83. 

 These are divisible into nine factors for nine equal divisions of 

 the gestation period, about as follows, 195.3, 118.7, 77.0, 52.7, 

 43.2, 35.6, 31.2, 27.5, 23.8, each factor being the number of ante- 

 natal deaths occurring in the corresponding month for each 

 1,000 born alive. The number of necessary conceptions, 1,605, 

 being applied to the first mortality factor, 195.3, and the number 

 of survivors to each succeeding term in order gives antenatal 

 death rates as follows: 121.7, 84.2, 59.6, 43.4, 37.2, 31.8, 28.8, 

 26.15, 23.23. 



We come to the beginning of the ninth month of gestation 

 with a mortality expectancy of 23.2 per 1,000 living unborn, 

 and to the beginning of the month of birth with a mortality 

 expectancy of 21 deaths per 1,000 winter babies born alive, and 

 for summer babies a mortality expectancy of 22.3 per 1,000 born 

 alive. The theoretical curve of antenatal mortality therefore 

 ends very near the level at which, under the conditions of 

 Neumann's tables, the statistical curve of post-natal mortality 

 appears to begin. We gain some formal notion of reproduction. 



