Dixon and Atkins — Extraction of Zymase by Means of Liquid Air. 7 



The above figures correspond to 0'57 eo. CO3 per gramme of residue or 

 0"29 CO per gramme of fresh yeast, as against O08 c.c. given by the juice 

 from the fresh yeast. 



These figures clearly show that a large amount of zymase is retained by 

 the cells. 



It is also remarkable that the cells, after exposure to liquid air, are 

 capable of taking up and retaining water, indicating that a condition of 

 equilibrium is not yet attained, although the membranes are permeable. 

 Culture experiments with the sediment showed that the exposure to the liquid 

 air had killed the yeast. 



In the hopes of obtaining part of the zymase remaining behind in the cells 

 we allowed a sample of frozen yeast to thaw in five times its weight of water, 

 and to macerate for twenty-four hours at room-temperature. After 

 centrifuging, 30 CCS. of the supernatant liquid, with 12 g. sugar, were set 

 to ferment under the usual conditions. 



No further evolution of gas. 



From this table it is clear that the actual amount of zymase extracted 

 may be much increased by dilution and maceration, as the yield was 2-2 c.c. 

 of COj per gramme of yeast. Of course the concentration of the enzyme is 

 greatly reduced. 



It appears then that the liquid-air method is as efficient as LebedefE's 

 method. It has the advantage of being very rapid. It requires only 

 30-40 minutes to prepare the zymase-containiug fluid from the solid yeast. 

 Also the time for changes taking place in the enzyme is reduced to a 

 minimum. 



The ease of the extraction of zymase by liquid air suggests its application 

 to the extraction of other endo-cellular bodies from bacteria, &c. This point 

 one of us is at present investigating along with Dr. A. Stokes. 



Finally, another possible use of this method may here be suggested. It 

 is generally held that sterilized food-stuffs are less assimilable owing to the 



