606 VEGETABLE ENZYMES. XIX 



solid preparation. It was therefore about fifteen times as active as 

 the insoluble sucrase preparation obtained directly from the banana 

 pulp. It showed a nitrogen content of 4.4 per cent; that is, about 

 four times as large as that of the latter. 



Amylase Results with Ripe Bananas. 



The amylase tests carried out with Lintner starch or with banana 

 starch, in which the amounts of reducing sugars were determined, 

 did not give definite evidence of the presence of a starch-splitting 

 enzyme. These tests were carried out with extracts and suspensions 

 prepared as described in the sucrase experiments. Before determin- 

 ing the amounts of reducing sugars formed, the mixtures were filtered 

 through paper and an aliquot of the filtrate taken. Undialyzed 

 extracts gave considerable blanks which increased on incubation 

 because of the sucrase action on the sucrose contained in the banana. 

 Dialyzed extracts gave little or no blanks. Isolated results at times 

 showed an apparent action, but the results were not consistent enough 

 or large enough to warrant the statement of a definite saccharogenic 

 action on the starch. The mixtures were tested at difl^erent hydrogen 

 ion concentrations and also in the presence of salt. The solid residue 

 from the extractions behaved similarly. 



In view of Bailey's positive results with the iodine test"* (amylo- 

 clastic in place of saccharogenic actions) and since he found more 

 marked actions with ripe than with unripe banana pulp, the reaction 

 was studied in this way also. The method described by him was 

 followed as closely as possible. It was found that, with the suspen- 

 sions of banana pulp on incubation with Lintner starch, precipitates 

 settled to the bottom of the tubes; that if these mixtures after incuba- 

 tion were tested with iodine after filtration, the filtrate gave no 

 starch reaction but the precipitate on the paper became blue; that, 

 if the whole mixture without filtering was shaken and tested with 

 ipdine, the precipitate was colored blue and settled leaving the super- 

 natant liquid colorless. It is probable, though not altogether clear 

 from the description of his experiments, that Bailey filtered or 

 decanted these mixtures before testing with iodine. If that was the 

 case, the amyloclastic actions which he described are open to ques- 



