8 INTRODUCTION. 



LOEW/ who has also opposed the view as to the oxygen becoming 

 active with the setting free of oxygen atoms, has sought for the reason 

 of the oxidations in the unstable properties of the protoplasmic pro- 

 teins. The active movement of the atoms within the active protein 

 molecule is transmitted to the oxygen and to the oxidizable substance, 

 and when this dissolution of the molecule has proceeded to a certain 

 point the oxidation occurs by virtue of the chemical affinity. The reason 

 for this unstable condition of living protein molecules has already been 

 given above. 



ScHMiEDEBERG, 2 who also denies the supposition that the oxygen 

 becomes active, io of the view that the tissues by the mediation of the 

 oxidations do not increase the oxidizing activity of the oxygen, but more 

 probably act on the oxidizing substances, making them more susceptible 

 to oxidation. 



All the views presented thus far assume a continuous oxidation of 

 the primary active substance. The view has also been suggested that 

 animal oxidation may be brought about by oxygen -carriers, i.e., by bodies 

 which, according to the older views, without being oxidized themselves, 

 act in a manner analogous to that of the nitric oxide in the manufac- 

 ture of sulphuric acid by alternately taking up and giving off oxygen in 

 the oxidation of dysoxidizable bodies. TRAUBE many years ago ex- 

 plained the oxidations of the animal body in this way, and he called 

 these questionable oxygen -carriers oxidation ferments. 3 



It is a fact that in the animal and plant kingdom bodies have been 

 extensively found which can bring about oxidations and which in many 

 respects behave like ferments or enzymes. It is therefore necessary, 

 before we proceed further, that we discuss the peculiar and highly 

 important bodies that have been called ferments or enzymes. The 

 nature, properties and mode of action of these bodies will be discussed 

 somewhat in detail in a following chapter (II), but in order to under- 

 stand what follows, we will give a short summary of the subject. 



Alcoholic fermentation by yeast and other processes of fermenta- 

 tion and putrefaction are dependent upon the presence of living organ- 

 isms, ferment fungi, and splitting fungi of different kinds. The ordinary 

 view, according to the researches of PASTEUR, is that these processes are 

 to be considered as phases of the life of these organisms. The name 

 organized ferments or ferments has been given to such micro-organisms, 

 of which ordinary yeast is an example. However, the same name has also 

 been given to certain bodies or mixtures of bodies of unknown organic origin 



1 Die chem. Energie d. lebenden Zellen. 2. Aufl. Stuttgart, 1906. 



2 Arch. f. exp. Path. u. Pharm., 14. 



3 M. Traube, Theorie der Fermentwirkungen. Berlin, 1858. 



