rEBRUAET 4, 1921] 



SCIENCE 



121 



K 





5 



Fig. 1. Showing the change in percentage which 



1919 for Vienna ( ) ; 1915 to 1919 for the 



land and Wales ( ). 



2. The drop in 1919 is sharp in its angle and 

 marked in its amount, the percentage coming 

 down nearly to the 1916 figure — and this in 

 spite of the very distressing conditions which 

 prevailed in Vienna throughout 1919. It is 

 not at all improbable, indeed rather it is prob- 

 able that Vienna will in 1920 show a ratio 

 under 100 — that is, more births than deaths. 

 If this happens she will have begun absolute 

 natural increase again in only the second year 

 after the cessation of hostilities, during the 

 last year of which she had 2i persons die for 

 every one bom. 



■ 3. The war produced no effect upon the 

 death-hirth ratio in this country, as would 

 have been expected. The influenza epidemic in 

 1918 raised the curve a little, but it promptly 

 dropped back to normal in 1919. 

 : 4. In England and Wales the provisional fig- 



deaths were of bdrtha in each of the years 1912 to 

 United States ( ) ; and 1912 to 1920 for Eng- 



ure indicates that 1920 will show a lower vital 

 index than that country has had for many 

 years. 



Altogether, these examples, which include 

 the effects of the most destructive war known 

 to modem man, and the most devastating epi- 

 demic since the Middle Ages, furnish a sub- 

 stantial demonstration of the fact that popula- 

 tion growth is a highly self-regulated biolog- 

 ical phenomenon. Those persons who see in 

 war and pestilence any absolute solution of the 

 world problem of population, as postulated by 

 Malthus, are optimists indeed. As a matter of 

 fact, all history definitely tells us, and recent 

 history fairly shouts in its emphasis, that such 

 events make the merest ephemeral flicker in 

 the steady onward march of population growth. 



Eaymond Pearl 



