igig] CURRE.XT LITERATURE 99 



the decrease in the rate depending upon the strength of the acid; the weaker the 

 the acid the greater the inhibiting action of its salt. The action of acetic 

 acid is completely paralyzed by the presence of sodium acetate equivalent to 

 the proportion of the acid. The effect of a salt other than the salt of the acid 

 used for the inversion depends upon the relations established between the acid 

 and the salt. An example would be HCl in the presence of sodium acetate; 

 NaCl and acetic acid are formed. If the acetate is present in sufiicient quan- 

 tity, all of the HCl is replaced by acetic acid, and if the acetate is still in excess, 

 we have inversion by acetic acid in the presence of its sodium salt, in which 

 case the hydrolysis is always inhibited. The author offers a similar explana- 

 tion for a situation reported by Davis and Daish. They found that 2 per 

 cent citric acid was sutTicient to invert a solution of cane sugar by boiling 10 

 minutes, but it was without effect in the presence of a certain quantity of 

 sodium acetate. The citric acid reacted with the sodium acetate, giving sodium 

 citrate and liberating an equivalent amount of acetic acid, the action of which 

 was paralyzed by its sodium salt still present in the solution. — Charles O. 

 Appleman. 



Effect of different oxygen pressures on carbohydrate metabolism of sweet 

 potatoes. — The experiments reported by Hasselbring" in this paper were 

 designed primarily to effect a further separation of the various steps in the 

 transformation of starch to sugar in sweet potatoes. For this purpose different 

 or>'gen pressures were employed. When the sweet- potatoes are killed under 

 a gas pressure of 5 atmospheres, starch hydrolysis is greatly depressed or in- 

 hibited. In the living potatoes starch hydrolysis and cane sugar formation 

 proceeded in the absence of oxygen in the same manner as in air or in an atmos- 

 phere of oxygen. Cruickshaxk working with barley seed, and Boysen- 

 Jensex working with germinating barley and peas, found that cane sugar was 

 not formed in the absence of oxygen. These investigators conclude that the 

 presence of oxygen is one of the necessary conditions for cane sugar formation, 

 but since this was not found to be the case with sweet potatoes, the conclusion 

 is not of general applicability. 



Anaerobic respiration in sweet potatoes consumes, in a given period of time, 

 a greater quantity of material than is consumed by normal respiration. The 

 energ>'^ derived from a given mass of material is less in anaerobic than in normal 

 respiration. These facts, coupled with the observation that cane sugar is 

 formed with equal facility under anaerobic and aerobic conditions, lead the 

 author to believe that his experiments in a general way support the Boysen- 

 Jensen theory that the respiratory processes furnish the energy for the syn- 

 thesis of cane sugar. In the case of the sweet potato this energy could be 

 furnished by anaerobic respiration. 



" Hasselbring, Heinrich, Effect of different oxygen pressures on the carbohy- 

 drate metabolism of the sweet potato. Jour. Agric. Research 14:273-284. 1918. 



