GENERAL CHEMISTRY OF LIFE PHENOMENA 13 



products of tryptic hydrolysis are found in considerable quantities, 

 while these products could be obtained in fresh and well-nourished 

 yeast only in minimal quantities. In this he sees, and probably cor- 

 rectly, an indication of the reversible action of the proteolytic enzymes. 

 There is, however, one essential link missing, i.e. the proof that the 

 hydrolytic action of the proteolytic enzymes is retarded, and finally 

 inhibited, when the products of digestion are not removed. 



R. O. Herzog has recently made an attempt to prove the reversible 

 action of enzymes in a very interesting way upon the discussion of 

 which, however, we cannot enter here. 



3. RESPIRATION AS A CATALYTIC PROCESS. OXIDATION AND OXIDASES 



By respiration we mean the taking up of oxygen and the giving off 

 of CO 2 . We shall see later that the latter process can exist indepen- 

 dently of the taking up of oxygen. 



Since the days of Lavoisier and La Place the real problem of oxida- 

 tion has consisted in the explanation of the fact that at the body tem- 

 perature our food stuffs are not oxidized at all, or only infinitely slowly, 

 outside the body, while in the body they are oxidized rapidly. The 

 solution of the problem was found in the discovery of "oxidizing fer- 

 ments" in living organisms. This conception is chiefly due to Moritz 

 Traube,* who was also the first to recognize that the oxidations occur 

 in the cells, and not, as had been assumed before, in the lungs or the 

 blood. 



Traube's idea was that there exist in the cells autoxidizable sub- 

 stances, i.e. substances which bind loosely the free oxygen at a com- 

 paratively low temperature, and which are capable of giving off their 

 oxygen to disoxidizable substances, such as our food stuffs. It is obvious 

 that Traube's idea of the action of an oxidizing ferment was that of 

 intermediary reactions. He realized also that these oxidizing ferments 

 exhibited no effects which could not be produced in inanimate nature, 

 as the following quotation shows: "The ability to transfer oxygen . . . 

 is found in many, even inorganic bodies. There are substances like 

 nitrogenoxide, platinum, various coloring matters, copper salts, which 

 are capable of transferring free oxygen upon neighboring substances." f 



* M. Traube, Ueber die Beziehiing der Respiration zur Muskelthatigkeit und die Bedeu- 

 tung der Respiration uberhaupt, 1861. Gesammelte Abhandlungen von M. Traube, p. 157, 

 Berlin, 1899. (In this paper Traube showed also that the work of the muscle is normally 

 done at the expense of carbohydrates. His arguments induced Pick and \Vislicenus to try 

 the classical experiment by which this theory was proved.) 



t M. Traube, Die Chemische Theorie der Ferment wirkttngen und der Chemismus der Res- 

 piration, 1878. Gesammelte Abhandl., p. 384, Berlin, 1898. 



