296 



POPULATIONS 



and 91, which are based on the data of 

 Table 22. 



The survivorship curve shows clearly the 

 initial drop owing to an infant mortaUty 

 component; the gradual decrease for about 



gevity and ecological mortality were devel- 

 oped (see page 273). 



The curve of deaths, or d^ describes in 

 reverse the survivorship graph. It has the 

 pictorial value, however, of an accentuated 



Table 22. Abridged Life Table for White Males in Continental United States, 1929 to 1931 

 (Adapted from Pearl, 1940; originally from Hill, 1936) 



fifty years, followed by the rapid decrease 

 in later life. The reader will recognize that 

 these l^ curves based on life table data are 

 similar in construction and principle to 

 those we discussed in the last chapter, in 

 which the concepts of physiological lon- 



ordinate scale. This emphasizes the rela- 

 tions between age and mortality. For exam- 

 ple, the high incidence of deaths during the 

 first year of hfe is excellently displayed in 

 the figure. 

 The death rate, or lOOO^^, curve plots for 



