INTRODUCTION. 3 



WOHLER iii 1824 furnished the first example of SYNTHETICAL 

 PROCESSES within the animal organism. He showed that when 

 benzoic acid is introduced into the stomach it reappears as hippuric 

 acid in the airine^ after its coupling with glycocoll (amido-acetic 

 acid). Since the discovery of this synthesis, which may be ex- 

 pressed by the following equation, 



C 6 H 6 .COOH + NH 2 .CH a .COOH=NH(C 6 H 6 .CO).CH 9 .COOH+H a O, 



Benzoic acid Glycocoll Hippuric acid 



and which is ordinarily considered as a type of an entire series of 

 syntheses occurring in the body where water is eliminated, the 

 number of known syntheses in the animal kingdom has increased 

 considerably. Many of these syntheses have also been artificially 

 produced outside of the organism, and numerous examples of ani- 

 mal syntheses of which the history is absolutely clear will be found 

 in the following pages. Besides these well-studied syntheses, 

 there occur in the animal body also similar processes unques- 

 tionably of the greatest importance to animal life, but of which we 

 know nothing with positiveness. We enumerate as examples of 

 this kind of synthesis the new formation of the red blood-corpus- 

 cles (the haemoglobin), the formation of the different albumins 

 from the peptones, the formation of fat from carbohydrates, and 

 others. 



The chemical processes in the animal body we have mentioned 

 above as consisting chiefly of oxidation and splitting processes. 

 The oxygen of inhaled air, as also that of the blood, is now called 

 neutral, molecular oxygen, and the old assumption that ozone occurs 

 in the organism has now been discarded for several reasons. There 

 are few substances which can be introduced from the outside, such 

 as aldehydic compounds and certain alcohols, for example benzyl- 

 alcohol (SCHMIEDEBERG), which can be oxidized within the animal 

 organism by the neutral oxygen; while, on the contrary, albumin 

 and fat, which form the chief part of the organic constituents of 

 the animal body, are almost indifferent to neutral oxygen. The 

 question arises, how then is the oxidation of these and other bodies 

 possible in the animal organism ? 



Formerly the view was generally accepted that ANIMAL OXIDA- 

 TION took place in the animal fluids, while to-day we are of the 



