SYNTHESIS AND OXIDATIONS. 3 



plants as the aroidece when bearing fruit a considerable development 

 of heat has been observed. On the other hand, in the animal organism, 

 besides oxidation and splitting, reduction processes and syntheses also 

 take place. The contrast which seemingly exists between animals 

 and plants consists merely in that in the animal organism the processes 

 of oxidation and splitting are predominant, while in the plant chiefly 

 those of reduction and synthesis have thus far been studied. 



WOHLER l in 1824 was the first to observe an example of the SYN- 

 THETICAL PROCESSES within the animal organism. He showed that when 

 benzoic acid is introduced into the stomach, it reappears as hippuric acid 

 in the urine after combining with glycocoll (aminoacetic acid). Since 

 the discovery of this synthesis, which may be expressed by the follow- 

 ing equation: 



C 6 H 5 .COOH + NH 2 .CH 2 .COOH = NH (C 6 H 5 .CO) .CH 2 .COOH + H 2 O, 



Benzoic acid Glycocoll Hippuric acid 



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

 theses 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 animal syntheses of which 

 the course is absolutely clear will be found in the following pages. Besides 

 these well-studied syntheses, there also occur in the animal body similar 

 processes unquestionably 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 re-formation of the red-blood pigment (the 

 haemoglobin), the formation of the different proteins from simpler sub- 

 stances, and the production of fat from carbohydrates. This last- 

 mentioned process, the formation of fat from carbohydrates, is also an 

 example of reduction processes which occur to a considerable extent in 

 the animal body. 



Formerly the view was generally accepted that ANIMAL OXIDATION 

 takes place in the fluids, while to-day we are of the opinion, derived from 

 the investigations of PFLUGER and his pupils, 2 that it is connected with 

 the form-elements and the tissues. The question as to how this oxida- 

 tion in the form-elements is induced and how it proceeds cannot be 

 answered with certainty. 



When a substance is oxidized by neutral oxygen at the ordinary 

 temperature or at the temperature of the body, the substance is said 



1 Berzelius, Lehrb. d. Chemie, iibersetzt von Wohler, 4, p. 356, Abt. 1, Dresden, 1831. 

 1 Pflviger, Pfliiger's Archiv, 6 and 10; Finkler, ibid., 10 and 14; Oertmann, ibid., 

 14 and 15; Hoppe-Seyler, ibid., 7. 



