8000 

 6000- 



\4OO0- 



2000- 

 1850 



/860 



1870 



1880 



1890 



1900 



/9/0 



MEMBERSHIP FOR PERIOD I850-I9IO 



1920 



MEMBERSHIP FOR PERIOD 1910-1940 



Horizontal and vertical scales are so chosen that equal slopes in the upper and lower 

 graphs correspond to the same rate of change in membership. 



No meetings were held in 1860-1865; Science became the official journal of the Asso- 

 ciation in 1900; records of membership are not available during the period of the World 

 War; the effects of the depression on membership began in 1931. 



ill 



