Dixon and Atkins — Extraction of Zymase hy Means of Liquid Air . 3 



No antiseptic was added in this experiment, but it is evident that the high 

 sugar concentration claecks bacterial action. A similar experiment gave the 

 following figures, the same quantities being used, with the addition of about 

 0'5 c-c. of toluene : — 



No further evohUion of gas. 



In this experiment the liquid at air-temperature was saturated with COj, 

 so that some of the gas evolved and caught in the burette was COa driven off 

 by the initial rise of temperature due to the transference into tlie thermostat 

 at 31°C. 



In another experiment with similar quantities, to which toluene was also 

 added, the liquid was not saturated with OOo, and the following figures were 

 obtained : — 



No further evolution of gas. 



In this experiment some of the same sample of sap was used as in the 

 previous experiment (No. 2). In the meantime (14 hours) the sap was standing 

 at ordinary room-temperature, and was presumably losing some of its 

 fermentative efficiency. Notwithstanding tliis, it exhibited a very fair activity. 



It was also noticed that while standing no evolution of CO2 took place. 

 This indicates that the sap obtained by the liquid-air method is practically 

 free from glycogen or other fermentable carbohydrates. 



The absence of fermentation from the supernatant liquid is in marked 

 contrast to the behaviour of the solid sediment. When the liquid is poured 

 off, the sediment froths actively, and in this respect behaves like the thawed 

 frozen yeast before centrifuging. Presumably the glycogen retained within 

 the cells is hydrolysed by the action of glycogenase which now has access to 

 it, giving fermentable sugars. The zymase present is thus provided with a 

 substrate. 



b2 



