PREFACE 
The present work is an attempt to apply facts dis- 
covered during the study of the physiology of nerves 
to living processes in general. ‘That mechanism char- 
acteristic of all living matter which enables it to respond 
to the external world is best developed in the nervous 
system. This mechanism may be called the most 
characteristic thing in life. The chemical accompani- 
ment, or basis, of this mechanism, discovered by the 
author in nerve fibers, he has hoped to show exists 
also in all forms of living matter, both of plants and of 
animals. It gives a chemical method of distinguishing 
living from dead tissue, and of measuring the quantity 
of life. 
This book, therefore, contains somewhat.in detail 
all the essential facts which he with his students has 
discovered from studies of the chemical changes in 
nerves accompanying functional change. In the pres- 
entation of this work, however, many important refer- 
ences and discussions have been omitted in order that 
the reader may not lose the main trend of the argument. 
The facts themselves are nevertheless given in the form 
of accurate numerical data so that the book may be 
useful also to the specialist whose interest lies more 
directly in the general physiology of the nervous system. 
In an appendix the detailed method for the use of the 
biometer is added in response to frequent requests of 
many friends and students who wish to use it for various 
biological and chemical researches. 
The author is deeply indebted to Professor A. P. 
Mathews for his criticism, scientific and literary, during 
the preparation of the work. Cee one 
January, 1917 
vii 
