SOME ASPECTS OF THE BIOLOGY OF HUMAN POPULATIONS 535 



In these equations y denotes population size and x denotes 

 time. 



It has been demonstrated statistically that populations 



o 



/oo 



75 



50 



-J 



25 



1800 20 40 60 80 1900 20 



Year 



Fig. 5. Observed and calculated growth of population of United States. 



of human beings have grown according to the logistic curve, 

 so far as may be judged from the available census records, 

 in at least the following countries: Sweden, United States of 

 America, France, Austria, Belgium, Denmark, England 

 and Wales, Hungary, Italy, Norway, Scotland, Servia, 

 Japan, Java, Phihppine Islands, Baltimore City, New York 

 City, and the world as a whole. 



In illustration of this statement three cases are presented 

 graphically here. These are the United States (Fig. 5), 



