914 



SCIENCE. 



[X. S. Vol. XXI. No. 540. 



to public health science, I must not fail to 

 speak. Here is a field absolutely ripe for 

 the harvest, but one in which the harvesters 

 ai'e as yet very few. I have lately had 

 occasion to examine somewhat carefully the 

 present condition of our knowledge of per- 

 sonal hygiene — which is nothing more (and 

 should be nothing less) than the applica- 

 tions of physiologial science to the conduct 

 of human life— with the result that I have 

 been greatly impressed with its vast possi- 

 bilities and promise. Man is a gregarious 

 animal, and mankind is to-day crowding 

 into cities as perhaps never before. More- 

 over, the industrial and commercial age in 

 which we live is characterized to an ex- 

 traordinary degree by the sedentary life. 

 Yet the sedentary life is almost unavoid- 

 ably an abnormal life, or at least it is a life 

 very different from that lived by most of 

 our ancestors. In the sedentary life the 

 maintenance of a high degree of physiolog- 

 ical resistance apparently becomes difficult, 

 and if the vital resistance of the community 

 in general is lowered then the public health 

 is directly and unfavorably affected, so 

 that considerations of personal hygiene 

 have a direct bearing upon the science of 

 public health. 



There are, to be sure, interesting and 

 suggestive symptoms of a wholesome reac- 

 tion, in America, at any rate, against the 

 evils of the sedentary life. Parks and 

 open spaces are being liberally provided; 

 public and private gymnasiums are rapidly 

 coming into being; public playgrounds are 

 thrown open in many of our cities, free of 

 expense to the laboring, but, nevertheless, 

 often sedentary, population ; vacations are 

 more than ever the fashion; sports and 

 games are everywhere receiving increasing 

 attention ; while public baths and other de- 

 vices for the promotion of personal hygiene 

 are more and more coming into being. All 

 this is as it should be, but all is as yet only 



a beginning. Here, again, the science of 

 education is sadly at fault and in the direc- 

 tion of educational reform as regards per- 

 sonal hygiene lies immense opportunity for 

 a contribution to public health science. 



The science of statistics, which has done 

 great service in public health science in 

 the past, is likely to do much more in the 

 future. Without accurate statistics of 

 population, mortality and the causes of 

 sickness and death, the science of epi- 

 demiology is impotent, and the efficiency 

 or inefficiency of public health measures 

 can not be determined. And yet in 

 ignorant hands statistics may be worse 

 than useless. It is a matter for congratu- 

 lation to Americans that we now have in 

 Washington a census bureau permanently 

 established and under expert supervision, 

 but until the various states and cities of 

 the United States follow this excellent ex- 

 ample of their Federal Government, one 

 of the most important aids to public health 

 science will continue to be Avanting, as is 

 unfortunately too often the case to-day not 

 only in America, but in many other parts 

 of the civilized world. 



William T. Sedgwick. 



Massaciu'setts Institute 

 OF Technology. 



SCIENTIFIC BOOKS. 

 Manual of the Trees of North America (Exclu- 

 sive of Mexico). By Charles Sprague Sar- 

 gent, director of the Arnold Arboretum of 

 Harvard University, author of the Silva of 

 North America ; with six hundred and forty- 

 four illustrations from drawings by Charles 

 Edward Faxon. Boston and New York, 

 Houghton MifHin and Company; Cambridge, 

 The Riverside Press. 1905. Pp. 24 + 826, 

 octavo. 



A few years ago Professor Sargent brought 

 to a successful close his monumental work, 

 ' The Silva of North America,' in fourteen 

 massive quarto volumes, and including de- 

 scriptions and figures of 585 speciea of trees. 



