viii EXTRACT FROM THE PREFACE TO THE FIRST EDITION 



that, except in the case of the simpler experiments and the chemical 

 work as a whole, which each student does for himself, it has been 

 found convenient to divide the class into groups of four, each group 

 remaining together throughout the session. It is possible that some 

 may find a group of four too large a unit, and it is certain that three, 

 or perhaps even two, would be better; but in a large school so 

 minute a subdivision is hardly possible, without entailing excessive 

 labour on the teachers. 



The systematic portion of the book is so arranged that it can 

 equally well be used independently of the practical work, and aims 

 at being in itself a complete exposition of the subject, adapted to 

 the requirements of the student of medicine. 



As to the matter of the text, it is hardly necessary to say that 

 this book does not aspire to the dubious distinction of originality; 

 and it is literally impossible to acknowledge all the sources from 

 which information has been derived. In many cases names have 

 been quoted, but names no less worthy of mention have often been 

 of necessity omitted. 



G. N. STEWART. 



CAMBRIDGE, 



September. 1895. 



