PKEFACE 



THIS book is intended for use as a combined textbook and 

 practical guide for a year's course of five hours per week. 

 It attempts to select from the fields of botany, zoology, and 

 human biology the essential facts and especially the great 

 ideas of the science of life which are of interest to the average 

 intelligent person who has no time and reason for more exten- 

 sive study of biology. 



The word " applied " in the title of this volume should not 

 be understood in the limited sense of economics, nor solely 

 with reference to human physiology and hygiene. It is true 

 that in these two lines biology has vastly important applica- 

 tions to human life, but it must not be overlooked that in 

 certain phases the science has value in the intellectual and 

 aesthetic life of cultured citizens. Hence, in the most liberal 

 interpretation, " applied biology " must present those facts 

 and ideas of the science which apply to human life in its 

 combined intellectual, esthetic, economic, and hygienic out- 

 look. It has been the aim of the authors to select for this 

 book the facts and ideas in these lines which seem best 

 adapted to that stage of education which for the vast majority 

 of students is the climax of formal education. In other words, 

 it has been attempted to present the science of biology applied 

 to the daily life of the average intelligent citizen. 



This book presents an order of study and selection of mate- 

 rials which have long appealed to the authors as a very 

 helpful answer to the widespread criticisms of the common 

 elementary courses of botany and zoology from the pure- 

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