X TRANSLATOR'S PREFACE 



the immediate sources from which I have obtained them, are mentioned in 

 the List of Illustrations. 



Finally, I wish to express my sincere thanks to Professor Graham Lusk 

 for many suggestions by which I have profited in my editorial capacity, and 

 to Professor Percy M. Dawson of the Johns Hopkins Medical School for 

 reading the entire proof. 



J. li. M. 

 NEW YORK, 1906. 



