188 The American Naturalist. [February, 



Europe... 8.7 per cent, by decade 



Africa 10 " " " 



Au-tralia and < K-eaniea 30 " " " ' 



North America 20 " " « 



South America 15 " " " 



Total 8 per cent, by decade 



With this ratio of increase as a basis, the figure .',,994,000,000 will 

 be attained A. D. 2072, or in about 181 years. 



It is a curious tact that this is very nearly the same date when, 

 according to the geologists, the coal supply of Great Britain, which 

 gives her prestige among nation-, will be exhausted. 



Our great-grandchildren will have reason to reflect upon the future 

 and the fate of their posterity doomed to struggle for life under the 

 hard conditions that maybe summarized in these words: want of 



officers for 1890-'91 were : Joseph Leid 

 Philadelphia, Pa., President; Frank Ba 

 C, 1st Vice President and Acting Presid 

 D., New York City, 2d Vice President ; 

 ington, D. C, Secretary and Treasurer. 

 Harrison Allen, M. I)., Philadelphia, P 

 Cornell University ; Thomas Dwight, M. 

 sity, President and Secretarv, ex-officio 

 Washington, I). C, Dele-ate to the Comri 



