15 



Tliunberg (1920), who observed that the animal oxidases 

 are also impaired l)y exposure to - 80°, suggests that they 

 might be modified in their structure in such a way that 

 they act only on some particular fraction of the substances 

 on which they acted before. 



According to d'Arsonal (1892), yeast, subjected for 

 24 hours to - 42° or for 45 minutes to about - 95°, furnished 

 an active sucrase; but if the enzyme, in a glycerin solu- 

 tion, was maintained for 45 minutes at -95°, it lost its 

 power of splitting sugar. 



Pictet and Yung (1884) subjected yeast successively 

 for 108 hours to - 70° and for 20 hours to - 130° ; they 

 found that it lost its power to raise bread. 



Yeast juice, exposed by Macfadyen (1900) for 20 hours 

 to the temperature of liquid air, furnished an active 

 zymase. 



Buclmer obtained zymase by grinding yeast in liquid 

 air or by grinding a mixture of yeast with solid carbon 

 dioxide ("Die Zymasegahrung. " Munich and Berlin, 

 1903. pp. 67 and 226). 



Rennet, in liquid preparations, exposed for 30 minutes 

 in liquid air, coagulated milk as effectively as did the con- 

 trols (Chanoz and Doyon, 1900). 



Pozerski (1900) investigated the action of an exposure 

 to the temperature of liquid air on the following enzymes 

 in solution (in test tubes) : salivary enzymes from human 

 saliva, sucrase from yeast, sucrase, amylase and inulase 

 from Aspergillus niger, tryspin, pepsin (a glycerin solu- 

 tion) and rennet. The activity of all these enzymes, after 

 45 minutes exposure, was found to be identical with that 

 of the controls. 



The coagulating enzyme of the blood was not destroyed 

 when oxalated dog blood, contained in a glass tube, was 

 exposed for 13 minutes to the temperature of liquid air ; 

 coagulation took place normally upon addition of calcium 

 chloride after thawing (Clianoz and Doyon, 1900). Since 

 the blood was oxalated, the fibrin-ferment itself was not 

 formed and the enzyme acted upon was the prothrombin. 



