OF THE 



I UNIVERSITY) 



OF 



PART I 



THE GENERAL PROPERTIES OF 

 LIVING TISSUES 



INTRODUCTION 



UNTIL recent times it was believed that many of 

 the compounds found in the tissues of animals 

 and plants could be made only by the action of 

 organized, i. e. living matter. Such compounds 

 were called organic to distinguish them from 

 those found in inorganic or inanimate nature. 

 The forces producing organic compounds were 

 thought to be partly the ordinary chemical 

 and physical processes known to science, and 

 partly certain mystical agencies termed vital 

 forces. The great discovery of Wb'hler in 

 1828 that urea (C02NH 2 ), a typical organic 

 compound, could be made synthetically in the 

 laboratory, overthrew this conception and was 

 the beginning of a long and fruitful struggle to 



