SOME ASPECTS OF THE BIOLOGY OF HUMAN POPULATIONS 547 



the unit elements are concerned. But it does not permit 

 entirely correct conclusions to be drawn in respect of the 

 important question as to the proportionate contribution of 

 each occupational group to the total population of the next 

 generation. 



The figures necessary to permit the discussion of this 

 point are given in Table vii, and are shown graphically in 



Figure 1 1 



Table vii 

 fertility of the occupational groups relative to the total 



population 



Occupational class (Reconstituted) 



Per cent 



in each 



class in 



1920 of 



males 45 



and over 



(a) 



Per cent 

 of more- 

 fertile 

 families in 

 1923 



(b) 



Professional service 



Clerical occupations 



Trade 



Domestic and personal service . 

 Public service 



Transportation 



Manufacturing and mechanical industries. 

 Agriculture, forestry, and animal hus- 



bandry. 



Extraction of minerals. 



Totals. 



S-77 

 1.66 

 6.71 

 2.40 

 0.94 

 4.44 

 32.57 



41-43 

 4.0^ 



100.00 



Per cent 



of total 



children 



ever born 



to families 



in column 



(b) 



(c) 



5 

 1 



5 

 I 



o 



4 

 33 



44 

 5 



75 

 10 

 56 



97 

 So 



15 



37 



47 

 05 



100.00 



While the general trend of Figure 1 1 is similar to that of 

 Figure lo, as it is in fact bound to be, Figure ii brings out 

 an additional bit of information that is not shown by Figure 

 10. What Figure ii shows is that in the first six occupa- 

 tional groups {Professional, Clerical, Trade, Domestic, 

 Public, and Transportation) the more fertile famihes in each 

 group form a smaller percentage of the total number of 

 more fertile famihes than the males forty-five years of age 

 and over, in that same group do, of the total number of 



