This work aimed to prepare a text-book on practical physiology for use in higher schools. The design of the book is to furnish a practical manual of the most 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, therefore, in this book, is to devote a certain amount of space to the structure of the several organs before describing their functions. A mere knowledge of the facts, concerning the structure and physiology of the human body, is of little real value or interest in itself. Such facts are important and of practical worth to 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.