SCIENC 



Friday, June 4, 1920 



CONTMNTS 

 The Effect of the War on the Chief Factors 

 of Population Change: Professor Raymond 

 Pearl 553 



Colored Photographs of Plant Disease Speci- 

 mens: Drs. Max W. Gardner and Geo. K. 

 K. Link 556 



William Dixon Weaver: William E. Keilt. . 558 



Btate Grants for Scientific Investigations in 

 England 559 



Scientific Events: — 



The Manufacture of Synthetic Ammonia in 

 England; Spanish Edition of the Jowrnal of 

 the American Medical Association; Grants 

 for Besearch made by TJie American Asso- 

 ciation for the Advancement of Science .... 562 



Scientific Notes and News 566 



University and Educational News 666 



Discussion and Correspondence: — 



Renewal of our Relations with the Scientific 

 Men of Europe: Dr. Henrt Fairfield Os- 

 BORN. The Meteor of November S6, 1919: 

 William Kelly. Formulm for Dates: Dr. 

 W. J. Spillman. The Library of the late 

 Professor Zuntz: Professor Tandell Hen- 

 derson 567 



Quotations: — 



WorTc of tlie Mayo Brothers 569 



The Journal of Mammalogy: Profebsor 

 CHABiES E. Johnson 569 



Special Articles: — 

 Fluorescence, Dissociation and Ionization 

 in Iodine Vapors: Drs. K. T. Compton and 

 H. D. Smyth 571 



The American Philosophical Society: Pro- 

 fessor Arthur Goodspeed 572 



MSS. intended for publication and books, etc., intended for 

 review should be sent to The Editor of Science, Garriaon-on- 

 Hudson, N. Y. 



THE EFFECT OF THE WAR ON THE 

 CHIEF FACTORS OF POPULATION 

 CHANGEi " 



There have recently appeared some figures^ 

 regarding the " mouvement de la population " 

 in France, Prussia and Bavaria whicli appear 

 to deserve somewhat more careful analysis 

 than they have received. These figures are 

 derived from official sources and are con- 

 veniently collected in the place to which I 

 have made reference. 



There are three factors fundamentally con- 

 cerned in producing changes in the absolute 

 size of the population in a given fixed area 

 (country, province, etc.). These are: 



1. The birth-rate, 



2. The death-rate, 



3. The net immigration rate. 



Of these factors the two first are, generally 

 speaking, of the greatest biological interest. 

 This is particularly true of such political 

 tmits as France, Prussia and Bavaria, where 

 in normal times net immigration makes no 

 significant contribution to the population. 

 Under war conditions permanent immigration 

 to these units was nil and may therefore be 

 safely neglected in the following discussion. 



The relation of birth-rate and death-rate 

 changes to population changes is a simple one 

 and may be put this way. If in a given time 

 unit the percentage 



100 Deaths 



Births 

 has a value less than 100, it means that the 

 births exceed the deaths, and that the popula- 

 tion is increasing within the specified time 



1 Papers from the department of biometry and 

 Vital statistics, School of Hygiene and Public 

 Health, Johns Hopkins University, No. 14. This 

 paper recently formed the basis of an evening's 

 discussion at the writer's seminar. 



2 Jour. Soc. Stat. Paris, Soixanti&me Annge, pp. 

 356-361, December, 1919. 



