THE CONNECTION OF OXYGEN RESPIRATION 89 



alcohol in the absence of oxygen if the fungus mat is immersed 

 in a sugar solution and is not left in a gaseous medium. Under 

 these conditions part of the products of metaboHsm diffuse into 

 the surrounding solution, whereby the poisoning of the fungus 

 is diminished. The more recent investigations of Kostychev 

 and Afanassjewa^ have weakened the question of the poisoning 

 of aerobic fungi. It has turned out that Aspergillus niger and 

 Penicillium glaucum, which under normal living conditions 

 tolerate very considerable concentrations of acid and grow 

 luxuriantly on a 5 per cent solution of free tartaric acid for 

 example, are severely poisoned by minimal amounts of acid in 

 the absence of oxygen. For example, a tartaric acid culture of 

 Aspergillus niger formed no ethyl alcohol on the same solution 

 which served very well for its previous development. After 

 the restoration of a weak alkaline reaction it was able to evoke 

 a considerable formation of alcohol by Aspergillus and Penicil- 

 lium. On sugar solutions Aspergillus niger was alone able to 

 produce alcohol under anaerobic conditions and with an acid 

 reaction. Penicillium glaucum was unable to form more than 

 traces of ethyl alcohol under these conditions. This result was 

 the more surprising because both fungi produce alcohol by the 

 gram with a slightly alkaline reaction (in the presence of CaCOs 

 and with oxygen excluded). The alcoholic fermentation of 

 these so-called "strongly aerobic" fungi was so considerable in 

 the experiments of Kostychev and Afanassjewa that the prog- 

 ress of C02-formation could be followed with the naked eye 

 by the development of bubbles. In Diakonow's experiments 

 as well as in those of Kostychev and Afanassjewa, Penicillium, 

 for example, on the surface of a slightly acid solution did not 

 produce a trace of alcohol, while the fungus mats which were 

 immersed in large quantities of sugar solution with neutral 

 reaction effected a normal alcoholic fermentation. 



Kostychev and Afanassjewa have also put an end to the idea 

 of a supposed distinction between feeding with sugar and with 

 non-sugars, so strongly emphasized by Diakonow. It was 

 found that various organic, nitrogen free nutrients, such as 

 glycerine, mannite, tartaric acid, quinic acid, and lactic acid 



1 Kostytschew, S. und M. Afanassjewa. Jahrb. f. wiss. Bot. 60: 628. 1921. 



