58 The Science of Life. 



It was in 1828 that Wohler (1800-1882) succeeded in 

 building up the characteristic organic waste product 

 urea from inorganic substances. This step in "chemical 

 synthesis" not only gave an impetus to the study of 

 other organic substances of physiological importance, 

 but it was fatal to at least one form of the prevalent 

 "vital-force theory", according to which organic sub- 

 stances were supposed to be only producible by living 

 organisms. The term "organic chemistry" began to be 

 replaced by "the chemistry of the carbon compounds", 

 which, if longer, has no theoretical implication. Wohler's 

 synthesis has been followed by many others equally 

 remarkable, e.g. of sugar; and various announcements, 

 such as Lilienfeld's, still requiring corroboration, lead us 

 to expect that the synthesis of proteids is not far off. 



Another pioneer was Justus von Liebig (1803-1873), 

 the first to attempt a systematic survey of the chemical 

 processes in living organisms. His great work, Chem- 

 istry in its Applications to Agriculture and Physiology 

 (1840; 8th ed., 1865), is still a classic, and has had an 

 influence only second to that which the author himself 

 had upon a large body of students. 



To appreciate the change which has taken place since 

 Liebig began his work, one has only to take an old 

 physiological text-book, with its minimum of chemistry, 

 and compare it with a good modern book such as Bunge's 

 or Halliburton's. 



For many years what was done was in the main 

 physiological chemistry analysing, naming, and record- 

 ing the distribution of organic substances in the body, 

 all very well in its way, but not very definitely physiolo- 

 gical. More recently, however, what has been done has 

 been more clearly chemical physiology, that is to say, an 

 association of the chemical composition of the substances 

 studied, with the vital phenomena in which they are, to 

 say the least, implicated. 



For another line of physiological progress it is more 

 difficult to find a name. By analogy it should be called 



Physical physical physiology, or physiological physics, 



Aspects. b u t both seem absurd. We mean the study 

 of the physical aspects of vital phenomena, the trans- 



