FROM THE PREFACE TO THE FIRST EDITION. 



IN this book an attempt has been made to interweave 

 formal exposition with practical work, according to a 

 programme which I have followed for some time past in 

 teaching Physiology to medical students on the other side 

 of the Atlantic, and which has, it is believed, proved to be 

 well adapted to their needs and opportunities. It ought, 

 however, to be explained that, for various reasons, a some- 

 what wider range of experiment is open to the student in 

 America than in this country. But as nobody will use this 

 book except in a regular laboratory and under responsible 

 guidance, it has not been thought necessary to mark in any 

 special manner the parts of the exercises which the English 

 student must do by proxy (that is, learn from demonstra- 

 tions), and the parts he ought to perform for himself. 



An arrangement of the exercises with reference to the 

 systematic course has this advantage that by a little care 

 it is possible to secure that practical work on a given 

 subject shall actually be going on at the time it is being 

 expounded in the lectures. Cross-reference from lecture- 

 room to laboratory, and from laboratory to lecture-room, 

 from the detailed discussion of the relations of a phenomenon 

 to the living fact itself, is thus rendered easy, natural, and 

 fruitful. 



As some teachers may wish to know how a course such as 

 that described in the Practical Exercises may be conducted 

 for a fairly large class, a few words on the method we have 



