544 



HUMAN BIOLOGY 



In the portion of the population here under discussion, the 

 figures show that when the average size of family produced 

 by a mother of 1923 in her total reproductive hfe up to 



12 



10 



a 







# 





In 



I 



Q: 



4- 



\ 



\ 



\ 



;/ 



Profess - Clerical Trade Dom- Public Transpor-Manufact -Agri- Mining 

 ional estic tation uring culture 



Fig. 10. Relative population and fertility by occupational classes. 



that time, by a father who fell in the Professional class and 

 was forty-five years of age or over in 1923, is taken as i.o, 

 the average size of family reproduced from mothers of 1923 

 by fathers who fell in the occupational class Extraction oj 

 minerals, and similarly aged torty-five years or over in 1923, 



was 1.9. 



The professional, capitalistic group exhibits the lowest 

 average size of family, and the labor groups, whether in 

 factories, farms or mines, the highest. The facts are shown 

 graphically in Figure 9. 



Let us now examine the relation between fertility, the 

 number ot more fertile families, and the total population 

 of occupied males, in the several reconstituted occupational 

 classes. This is done graphically in Figure 10, on the basis 



