218 VEGETABLE ENZYMES, XVIII 



starch in water to the requisite amount of boiling water, boiling for 

 1 to 2 minutes, and coohng rapidly. The added sugars which were 

 used (sucrose and maltose) were the purest obtainable. The results 

 were calculated to correspond to 15 cc. of the original mixture, except 

 where stated otherwise, and are given in terms of mg. of cuprous 

 oxide obtained. 



Sherman and Schlesinger'' compared the amyloclastic and saccharo- 

 genic actions of certain amylases, and pointed out clearly the signifi- 

 cance of these actions. In this paper, the saccharogenic actions of 

 the enzymes in potato juice, as determined by the amounts of reduced 

 products, are followed and not the amyloclastic (spUtting of starch 

 into products which do not give a blue color with iodine). While 

 the two ways of determining the actions undoubtedly overlap to a 

 certain extent, the differences must also be borne in mind. In any 

 event, the chemical changes in either case are not known except with 

 the disaccharides used, so that a strictly quantitative comparison of 

 the actions is not so certain as in other enzyme actions. The possi- 

 bility of a small amount of cuprous oxide being held in solution by 

 other substances present in the juices must also be considered. 

 Attempts were made to eHminate this and other sources of error 

 by running blanks wherever possible. 



The solutions were brought to definite hydrogen ion concentrations 

 before mixing by the addition of sodium hydroxide or hydrochloric 

 acid solutions of various concentrations and tested with the indi- 

 cators recommended by Clark and Lubs.^ 



Experimental Results. 



The properties of the juices from the different lots of potatoes 

 varied somewhat. In general terms, the specific gravities of the 

 juices from new and winter potatoes ranged between 1.025 and 

 1.035, those from sprouted potatoes (only small, shriveled ones 

 were obtainable) somevv^hat higher, from 1.035 to 1.040. Ahnost 

 twice as much juice was obtained from the former as from the latter, 

 approximately 20 to 30 per cent by weight of the original solid with 



'^ Sherman, H. C, and Schlesinger, M. D., J. Am. Chem. Soc, 1913, xxxv, 1784. 

 8 Clark, W. M., and Lubs, H. A., /. Bactcriol, 1917, ii, 1, 109, 191. 



