First Edition, August, 1923 



Second Edition, December, 1925 



Third Edition, January, 1930 



Fourth Edition, March, 1934 



Preprint of pages ix + 79 of Fifth Edition, October, 1938 



Fifth Edition, April, 1939 



Copyright, 1948 

 The Williams & Wilkins Company 



Made in United States of America 

 Published January, 1948 



Composed and Printed at thb 

 WAVERLY PRESS, INC. 



FOS 



The Williams & Wilkins Compajjy 



Mt. Royal and Guilford Aves. 



Baltimore, Md., U. S. A. 



