Physiologie. 335 



contain. At 50' C the evolution of CO 2 is rapid, but is soon 

 arrested by liquefaction: the langest amount of glycogen is fer- 

 mented at 2b" C, representing about 16.8 per cent. of the dry 

 Yeast present. 



The absorption of had hitherto been studied with Yeast 

 suspended in water: the authors observed it with pressed Yeast. 

 When Yeast is exposed to a current of oxygen, the temperature 

 rises considerably, and respiration is active. In an experiment 

 in which 69.1 grms of Yeast were used, and which lasted for 

 4.6 hours, the temperature rose from 16. 5^ to 41.35", 1103 cc 

 of were absorbed and 2148 cc of CO 2 evolved, the respiratory 



CO' 

 qiiotient —^ being 1.94. A comparison of the gaseous inter- 



change in the absence and in the presence of gave results 

 such as the following: 100 grms of Yeast at 39*' in the absence 

 of gave out 1730 cc CO 2: the same weight in a current of 

 evolved 2090 cc of CO 2 and absorbed 844 cc of 0: hence the 

 excess of CO 2 evolved in the presence of was 360 cc and 

 the respiratory quotient 0.43. If the oxidised the glycogen 

 completely, the vol. of CO 2 evolved should be three times that 

 evolved were the glycogen completely fermented: so that the 

 difference between the vol. of CO 2 evolved in the presence of 

 O and that evolved in its absence should be two thirds of the 

 absorbed. But as the ratio of the CO2 evolved to the 

 absorbed was found to be much less than two thirds, the 

 authors suggest that probably CO 2 and H2O are not the only 

 products of oxidation. 



Microscopical examination of the Yeast-cells at different 

 stages in the process of liquefaction showed that, as the evolu- 

 tion of CO 2 proceeds, the vacuole increases in size and the 

 brown colouration with iodine diminishes. After liquefaction 

 the cells have no vacuole and are shrunken, the cell-contents 

 being aggregated into a central granulär mass. It seems pro- 

 bable that liquefaction is due to the discharge of the contents 

 of the vacuole, and that the previous increase in the size of the 

 vacuole indicates the accumulation of some substance produced, 

 along with CO2, from the glycogen. The cell-wall remained 

 distinct throughout. G. H. Vines (Oxford). 



KosiNSKY, J., Die Athmung bei Hungerzuständen und 

 unter Einwirkung von mechanischen und che- 

 mischen Reizmitteln bei Aspergillus niger. (Prings- 

 heim's Jahrbücher für wissenschaftliche Botanik. 1901. Bd. 

 XXXVIl. p. 137.) 



Der auf die Entziehu n g der Nahrung folgende Hunger- 

 zustand des Pilzes verursacht zunächst ein plötzliches, erhebliches 

 Sinken der Athmung, die dann auf Kosten des Zellinhalts noch 

 längere Zeit mit sinkender Energie weiter geht. A. niger stellt 

 somit den Typus eines Pilzes dar, der sehr kleine Mengen von 

 Nährstoffen ansammelt und die Nahrung direct dem Substrat 



