Copyright, igis, by W. B. Saunders Company. Revised, entirely reset, 

 reprinted, and recopyrighted February, 1920 



Copyright, 1920, by W. B. Saunders Company 



Reprinted September, 1921 



PRINTED [N AMERICA 



PRESS OF 



W. o. 8AUN0ERS COMPANY 



PHILADELPHIA 



