332 A. P. MATHEWS. 



The only general theory of the nature of respiration which has 

 been carefully worked out is that of Hoppe-Seyler. 1 According 

 to this hypothesis there occurs in the cell a fermentative decom- 

 position of some substance analogous in all respects to the fer- 

 mentative decomposition of calcium formate by many bacteria. 



(CHO 2 ) 2 Ca -f H 2 O = CaCO 3 + CO 2 + 2H 2 



By this fermentation nascent hydrogen is set free ; the nascent 

 hydrogen keeps the protoplasm in its reduced state ; it com- 

 bines with one atom of the oxygen of the air to form water and 

 sets free the other atom as nascent oxygen which thus causes the 

 intense oxidations of protoplasm. This hypothesis was attacked 

 by Traube, who showed in many cases that the process included 

 the formation of hydrogen peroxide which was the real oxidizing 

 agent. Hoppe-Seyler demonstrated, however, that some of these 

 oxidations were more powerful than hydrogen peroxide, which 

 is not a very strong oxidizing agent, could produce. 



With the discovery of the oxidases, Hoppe-Seyler's hypoth- 

 esis has fallen into the background without the oxidase hypoth- 

 esis giving a better explanation in its stead. The manner of 

 action of the oxidases is still obscure ; their chemical composi- 

 tion is unknown, and no oxidase will cause oxidations in the 

 absence of oxygen, whereas many forms of protoplasm can carry 

 out such oxidations in the presence of no free oxygen at all or 

 only of traces of free oxygen. 



The studies of Armstrong, Dixon and others on the pro- 

 cesses of slow and explosive oxidations and combustions throw, 

 in my opinion, a remarkably clear light on protoplasmic respira- 

 tion. These authors have shown that in ordinary oxidation the 

 presence of some water is necessary to the oxidation. Phos- 

 phorus in a perfectly dry state will not ignite in dry air. Arm- 

 strong 2 concludes that the primary oxidation in all these cases 

 is not brought about by the gaseous oxygen, but by the water. 

 The atmospheric oxygen acts the part only of a depolarizer to 



take care of the nascent hydrogen formed from the water. 



1 Hoppe-Seyler, Physiologische C/rewie, I. Theil, Allgemeine Biologic, p. 126 ff. 

 Berlin, 1877. 



2 Armstrong, Chemical News, July 15, 1904, vol. 90, p. 25; Transactions Chem- 

 ical Soc., vol. 63, p. 1088, 1903. 



