552 RESPIRATION AND FERMENTATION 



a theory of fermentation upon this assumption, and postulated the possibility of 

 an extracellular extension of these vibrations, and hence of vitalistic fermentation 

 also. Nageli cites the extracellular reduction of litmus as an argument in support 

 of this theory, but this reduction is not, however, performed by pure cultures 

 of actively fermenting yeast, and Chudiakow ' has shown that Nageli's other 

 arguments do not coincide with the facts observed. The small size, and hence 

 relatively enormous surface-area, of ferment-organisms render possible more rapid 

 exchanges than are required by the most active intracellular fermentations. 

 (Nageli, 1. c., p.. 37.) 



Historical. After Pfliiger had indicated the decomposition continuing in the 

 absence of oxygen as being the direct cause of oxygen-respiration in animals, Pfeffer 

 pointed out the genetic relationship between intra-molecular- and oxygen-respiration 

 in plants 2 , and subsequently put forward the conclusions here expounded 3 . 

 The same studies definitely established the relationship between aerobic and 

 anaerobic respiration which had been denied by Godlewski, Bowdin, Reinke, &c., 

 and proved the incorrectness of Nageli's supposition that intra-molecular respiration 

 is a meaningless physiological phenomenon. It was also proved that molecular 

 oxygen is drawn into metabolism without being ozonized (Sect. 101), and that in 

 the absence of oxygen no such reducing influences are generated in the protoplast 

 as would withdraw oxygen from easily reducible substances (Sect. 102). 



Pasteur assumed the existence of a certain connexion between intra-molecular 

 respiration and anaerobic fermentation, and Pfeffer showed that the latter was 

 simply a specially adapted modification of the former, and in certain cases 

 acquires so inherent a character that the fermentative activity of anaerobic 

 metabolism may continue or even be accelerated in the presence of free oxygen. 

 This latter fact does not coincide with Pasteur's view 4 that in the absence of free 

 oxygen this gas is withdrawn from other compounds and thus directly excites 

 fermentative activity, but at a time when oxygen-respiration was regarded as an 

 absolute essential for life, this theory served to render the phenomenon of 

 anaerobiosis discovered by Pasteur more readily comprehensible. At a later date 

 Pasteur 5 apparently laid no especial importance upon this theory, but simply 

 regarded the process of fermentation as the source of the necessary supply of 

 energy. The same general view applies also to those cases of anaerobiosis which 

 are not characterized by any special fermentative activity, for the utilization of the 

 liberated energy is not dependent upon the quantity of material decomposed, 

 and in aerobes the necessary energy may be obtained with or without the aid 

 of fermentation. Since katabolism continues in adult organs, Pasteur was in error 



1 Chudiakow, Landw. Jahrb., 1894, Bd. xxill, p. 454. Cf. also Ad. Mayer, Zeitschr. f. Biol., 

 1882, Bd. xvni, p. 523 ; Lafar, Techn. Mykologie, 1897, Bd. I, p. 20 (here the different theories of 

 fermentation are mentioned). 



2 Pfliiger, Archiv f. Physiol., 1875, Bd. x, p. 251 ; Pfeffer, Landw. Jahrb., 1878, Bd. vil, p. 805. 



3 Pfeffer, Unters. a. d. Bot. Inst. z. Tubingen, 1885, Bd. I, p. 636; Oxydationsvorgange, 1889, 

 p. 480. 



4 Pasteur, Compt. rend., 1861, T. Lll, p. 1260. 



5 Ibid., 1875, T. LXXX, p. 452 ; tudes s. 1. biere, 1876, p. 258. 



