PREFACE TO THE SECOND EDITION vii 



In the old method, the stress is upon the di- 

 dactic teaching. In the new there is no less 

 didactic teaching, but the stress is upon observa- 

 tion. The old method insensibly teaches men to 

 rest upon authority, but the new directs them 

 to nature. 



The new method requires : 



1. Printed accounts of the fundamental experi- 

 ments and observations in physiology, taken from 

 the original sources, and arranged in the most 

 instructive sequence. The reference to the origi- 

 nal source should be given in each case. 



2. Accessory data grouped about the funda- 

 mental experiments. The accessory data should 

 also be taken as directly as possible from the 

 original sources, and the reference given in each 

 case. 



3. Apparatus of precision designed with the 

 utmost simplicity upon lines that permit its 

 manufacture in large quantities at small cost. 



It is obvious that these conditions cannot be 

 met without prolonged labor. Meanwhile, the 

 annual classes in physiology must be taught. 

 The present volume is a collection of fundamen- 

 tal and accessory experiments in several fields 

 printed in an abbreviated form for the temporary 

 use of Harvard Medical students and other inter- 

 ested persons. This collection is being completed 



