Produced by Distributed Proofreaders [Transcriber’s Note: Figures 162-167 have been renumbered. In the original, Figure 162 was labeled as 161; 163 as 162; etc.] [Illustration] A Practical Physiology A Text-Book for Higher Schools By Albert F. Blaisdell, M.D. Author of “Child’s Book of Health,” “How to Keep Well,” “Our Bodies and How We Live,” Etc., Etc. Preface. The author has aimed to prepare a text-book on human physiology for use in higher schools. The design of the book is to furnish a practical manual of the more important facts and principles of physiology and hygiene, which will be adapted to the needs of students in high schools, normal schools, and academies. Teachers know, and students soon learn to recognize the fact, that it is impossible to obtain a clear understanding of the functions of the various parts of the body without first mastering a few elementary facts about their structure. The course adopted, therefore, in this book, is to devote a certain amount of space to the anatomy of the several organs before describing their functions. A mere knowledge of the facts which can be gained in secondary schools, concerning the anatomy and physiology of the human body, is of little real value or interest in itself. Such facts are important and of practical worth to young students only so far as to enable them to understand the relation of these facts to the great laws of health and to apply them to daily living. Hence, it has been the earnest effort of the author in this book, as in his other physiologies for schools, to lay special emphasis upon such points as bear upon personal health. Physiology cannot be learned as it should be by mere book study. The result will be meagre in comparison with the capabilities of the subject. The study of the text should always be supplemented by a series of practical experiments. Actual observations and actual experiments are as necessary to illuminate the text and to illustrate important principles in physiology as they are in botany, chemistry, or physics. Hence, as supplementary to the text proper, and throughout the several chapters, a series of carefully arranged and practical experiments has been added. For the most part, they are simple and can be performed with inexpensive and easily obtained apparatus. They are so arranged that some may be omitted and others added as circumstances may allow. If it becomes necessary to shorten the course in physiology, the various sections printed in smaller type may be omitted or used for home study. The laws of most of the states now require in our public schools the study of the effects of alcoholic drinks, tobacco, and other narcotics upon the bodily life. This book will be found to comply fully with all such laws.