SOME ASPECTS OF THE BIOLOGY OF HUMAN POPULATIONS 529 



III and ix). Sweeney has made an interesting and com- 

 prehensive examination of the vital indices of all the popula- 

 tions of the world for which records of births and deaths 

 exist. 



Using the vital index as a measure of the phenomena we 

 may now discuss two examples of autonomic regulation 

 in a human population. The first concerns the population of 

 England and Wales. For each quarter of each year from 

 1838 to 1920 inclusive the vital index of the population was 

 computed. Grouping the data in five-year periods gives the 

 results shown in Table v. 



Table v 

 grouped data for vital index and crude birth rate of england and 



WALES 



The immediately striking feature of this table is the 

 general smoothness of the trend of the values of the vital 

 index as one runs down the column. In order to appreciate 



