lOO PLANT RESPIRATION 



Both assumptions are not unlikely for the following reasons: 

 With potato tubers and fruiting bodies of Psalliota campestris 

 not the least formation of alcohol was observed in the absence 

 of oxygen^ although the former contain sugar while the mush- 

 rooms contain considerable amounts of mannite. It was found 

 by analyses that a considerable part of the mannite in Psalliota 

 is consumed when oxygen is excluded ;2 there was likewise a 

 consumption of sugar in the potato tubers. On the basis of 

 specific experiments of the author, discussed later, the con- 

 sumption of mannite by aerobic molds in the absence of oxygen 

 is nothing but the formation and fermentation of sugar (fruc- 

 tose). It is natural to assume that mannite is also worked up 

 in the anaerobic respiration of the mushrooms by way of sugar 

 as an intermediate. This is all the more probable because, with 

 access to oxygen, a formation of sugar from mannite takes 

 place to a large extent in these plants. It is also hardly con- 

 ceivable that the working up of sugar in potatoes is not effected 

 by the use of zymase, for in all the seed-plants the cleavage of 

 sugar has so far been found to take place only through alcohohc 

 fermentation. On the strength of all these considerations it is 

 natural to assume that, in the above plants as well as in other 

 cases in which there appears a considerable surplus of CO-2 with 

 the exclusion of oxygen and the disappearance of sugar, the 

 alcoholic fermentation takes a somewhat abnormal course and 

 an intermediate product of fermentation is converted in part 

 into other substances. 



According to the view of the author of these lines, only acetal- 

 dehyde can be considered in the cases before us, because ethyl 

 alcohol is formed from acetaldehyde by the absorption of hydro- 

 gen after CO2 has been spHt off.^ Important reasons favor the 

 assumption that in alcohohc fermentation there arises, by 



1 Kostytschew, S. Ber. d. bot. Ges. 25: 188. 1907; 26a: 167. 1908; 31: 125. 1913. 



2 Kostytschew, S. Z. f. physiol. Chem. 65: 350. 1910. 



i Stoklasa does not accept this theory of the formation of alcohol (in the 

 anaerobic phase of respiration) but considers that it arises from lactic acid 

 through the removal of a molecule of carbon dioxide. Acetaldehyde, acetic 

 acid and formic acid are formed later by way of the alcohol. Stoklasa's 

 recent paper (Ber. d. bot. Ges 44: 248-262. 1926) reviews the problem and 

 presents some new e.xperimental evidence. — Ed. 



