OF VITAL PHENOMENA 167 



oxidases. With the search for oxidases many have been found 

 and some of them seem to be specific. The fact, however, that 

 no series of oxidases with which the complete oxidation of the 

 ordinary foodstuffs can be accomplished have yet been isolated 

 from the organized cell or cell fragment, places the question of 

 oxidations in a separate field of research from enzymes in gen- 

 eral. Harden and McLean (1911) found that respiration did 

 not occur in the press juice of muscle and some other tissues. 

 Batelli and Stern (1909) confirmed this observation but claim 

 that respiration occurs in the press juice of liver. Warburg 

 (1913) showed that most of the oxidation in liver juice is asso- 

 ciated with granules. Whereas the oxidation of the liver juice 

 is 20 per cent of that of the intact liver or liver cells, the oxidation 

 of the juice after having passed a Berkefeld filter is only 4 per 

 cent of that of the liver. As shown by Bechhold, such treatment 

 may not remove all of the colloidal particles. Warburg found that 

 the granular mass of ground sea urchin eggs absorbs oxygen but 

 does not give out C0 2 . Warburg and Meyerhof (1914) found 

 that the lecithin extracted from the egg when mixed with a ferric 

 salt the equivalent of the iron in the egg, absorbed as much 

 oxygen as the ground egg. This is probably due to the oxidation 

 of unsaturated fatty acid radicals in the lecithin, and is accelerated 

 by H ions. A similar reaction takes place in linseed oil and is 

 accelerated by various metallic and organic oxides or peroxides. 

 Warburg (1912 a) ground young erythrocytes (with rapid 

 respiration) in a special ball mill (Macfadyen and Rowland) 

 and the oxidation was reduced to zero. 



Much of the earlier theoretical work on oxidations is based on 

 the assumption that 2 is relatively inert and that nascent oxygen 

 or some active oxide or peroxide is necessary to affect oxidation 

 of difficultly oxidizable substances. This follows from the fact 

 that oxidation consists in the addition of a positive charge or 

 valence to the molecule. The molecule thus charged may com- 

 bine with OH, or if the charge is double it may combine with 

 one atom of oxygen. What is meant by nascent oxygen is not 

 clear. Perhaps some substance splits out O" from 2 , thus leav- 

 ing O" which can exist only in a nascent state because it so easily 

 parts with its positive charges, and in doing so oxidizes the sub- 

 stance receiving them. 



