vi PREFACE. 



istry and physiology, however, have been introduced into the text 

 as a matter of historical interest. 



To my friend, Mr. Charles Glaser, of Baltimore, I wish to 

 express my sincere thanks for many valuable suggestions and aid 

 in the revision of the manuscript. To Messrs. Lea Bros. & Co. 

 I am indebted for many acts of courtesy. 



1302 MADISON AVENUE, 

 BALTIMORE, MD., 1901. 



