538 



HUMAN BIOLOGY 



these having been carefully made by the French. In this 

 case the human population followed in its whole cycle of 

 growth a simple logistic curve. This case has been fully 



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1856 le&l 1866 1871 1876 1381 1886 1891 1896 1901 1906 1911 1916 1921 I9JZ6 193/ 



YEAR 



Fig. 8. Observed and calculated growth of indigenous native population of 



Algeria. 



described and analyzed in the writer's book "The Biology 

 of Population Growth" and is illustrated here in Figure 8. 



The logistic curve, which is found by actual experience 

 to describe accurately the course of population growth in a 

 wide variety of organisms, constitutes a valuable first step, 

 but only a first step, towards reaching an understanding 

 of the biology of the process. What we want to know is how 

 the biological forces of natality and mortality are so inte- 

 grated and correlated in their action as to lead to a final 

 result in size of population which follows this particular 

 curve rather than some other one. 



In the laboratory a series of investigations, experimental 

 mathematical, and statistical, has been carried out for the 

 purpose of throwing light on the problem. Limitations of 

 space make it impossible to do more here than give a brief 

 resume of the results to date. A full account of these investi- 

 gations is given, however, in certain of the references listed 



