436 



G. P. PLAISANCE AND B. W. HAMMER 



oil to the flasks of liquids to be fermented might materially 

 modify the results obtained. A number of comparisons of 

 oiled and unoiled material were made at room temperature, 

 using a juice expressed from cane and to which 2 per cent sucrose 

 had been added before sterilization; the results secured are 

 presented in table 2. From the data given it is evident that 

 under the conditions employed, a larger percentage of mannitol 

 was secured with oil than without it. Because of the gas liber- 

 ated, which probably drives off much of the unconsumed oxygen, 

 the conditions in the unoiled flasks must be, to a certain extent, 

 anaerobic and this, in all probability, explains the formation of 

 mannitol in the absence of oil. Whether the presence of air 

 results in a smaller production of mannitol or in a destruction 



TABLE 2 

 The influence of oil on mannitol production, room temperature incubation 



of a portion of that produced is impossible to determine from the 

 data available. 



In general, during the fermentation of the juices used there 

 was a pronounced change in color; in the unoiled flasks the lighter 

 portion involved mainly the lower depths, due presumably to the 

 air above, while in the oiled flasks practically the entire liquid was 

 involved. It seems probable that the change in color involved 

 a reduction of some indicator present in the fermenting juice, 

 the process being essentially similar to the reduction of litmus 

 by many organisms, although it is possible that the change in 

 color was due to the production of acid; the latter explanation 

 is less acceptable than the former since the change in color in 

 general agrees with the state of anaerobiosis. 



