iv PREFACE TO REVISED EDITION 



in each chapter on such points as bear directly upon 

 personal health. 



In this book, as in the other books of this series of 

 school physiologies, there has been added to the text a 

 number of carefully graded and practical experiments suffi- 

 ciently varied to allow a wide range of choice. For the most 

 part they are simple and can be performed with apparatus 

 that is inexpensive and easily obtained. 



This book complies fully with the laws of those states 

 which require in their public schools the study of the 

 nature and effect of alcohol, tobacco, and other narcotics 

 upon the human system. 



The author would acknowledge his indebtedness to Dr. 

 Margaret B. Wilson of the New York Normal College for 

 careful criticism of his manuscript and for valuable assist- 

 ance and suggestions in reading the proofs, and also to 

 Professor H. W. Conn of Wesleyan University for the use 

 of a number of illustrations from his work on bacteria, 

 recently issued by the publishers of this book. 



A. F. BLAISDELL 



WINCHESTER, MASS. 

 March, 1904 



