PKEFACE 



IN the preparation of this book an attempt has been 

 made to combine the following features : 



(1) As the title-page implies, emphasis is constantly laid 

 on physiology, and anatomical details are given only so far 

 as is necessary to make intelligible the various physiological 

 processes. Hygiene is discussed in a separate section at 

 the end of the study of each system ; for, while believing 

 that the lessons of hygiene are of primary importance, the 

 author is confident that a youth will learn these lessons 

 best by getting some comprehension of the normal action 

 of his various organs. 



(2) An experience of ten years in teaching physiology to 

 high school pupils has demonstrated that laboratory work 

 on the part of the pupil is by far the most satisfactory 

 method of presenting this subject. While this book is not 

 a laboratory guide, it is intended to lead the pupil to study 

 the organs and tissues of his own body or those of other 

 animals rather than to learn text-book statements about 

 them. Experiments and demonstrations should, therefore, 

 precede the study of a given topic in the text-book. (See 

 Peabody's "Laboratory Exercises in Anatomy and Physi- 

 ology." Henry Holt & Co., New York City.) ' 



(3) Physiological processes can never be understood by 

 pupils unless they are taught at least some of the simpler 

 principles of chemistry. For this reason the early chapters 

 of the book are devoted to a discussion of the common 

 elements and their compounds, to atmospheric pressure, 

 oxidation, and neutralization. 



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