AUTOPHAGY OR AUTOLYSIS OF YEASTS 105 



tion in water to which a little antiseptic has been added (creosote, 

 toulol, phenol, etc.). The yeast is reduced to live at the expense of 

 its glycogen which it has laid up in reserve and to attack its protein 

 substances. Then, two phases may be distinguished in autophagy, 

 first, the fermentation of glycogen and, secondly, the proteolysis of 

 its own protein substances. 



Glycogenase which is contained in the cells acts on the glycogen 

 and causes a fermentation (autof ermentation) . The principal prod- 

 ucts formed under these conditions are alcohol, carbon dioxide, 

 glycerol, and according to Salkowski, succinic acid. The fermenta- 

 tion of glycogen is then quite analogous to intramolecular respira- 

 tion which is noticed in fruits containing sugar when placed away 

 from air. 



The yeast, at the same time, attacks albuminoid materials by 

 means of its endotryptase and other proteases (guanase and argin- 

 ase) which seem to play a very important role. The products of 

 this digestion are nucleic bases, tyrosine, leucine, guanine, lysine, 

 arginine, aspartic acid (Kutscher) and choline. Autophagy depends, 

 according to Effront, not on the cells but on the enzymes which are 

 formed in the cells when placed in inanition. In the presence of water 

 the hydroxy compounds of carbon disappear with the liberation of 

 carbon dioxide. The cells die rapidly at the end of about 6 days. 

 In the presence of alcohol (7 per cent) and a little hydrofluoric acid, 

 Effront l has been able to obtain a proteolysis of albuminoid sub- 

 stances; under these conditions the yeasts are easily able to support 

 a denutrition without losing their fermenting power. 



1 Effront, J. Sur 1'autophagy de la levure. Moniteur scientific, 1905, 16. 



