•240 Alfred J. Ewart .■ 



10 c.c. of dilute 0.05 per cent, starch solution. In the control 

 all the starch dissolved at 35o C. in 3 hours, but even after 1 

 •day abundance of starch was present both in (a) and (b), and a 

 large coagulum separated out containing nearly all the starch. 

 After two days the starch was still undissolved, Vjut more reducing 

 sugar seemed to be present than in the control. The clear liquid 

 •turned pale yellow with NaHO , and contained tannic acid de- 

 rived from the apple sap, but a good deal of the tannic acid com- 

 bines with the proteids of the tissue, or is carried down by the 

 precipitated starch. 



In a similar test there were added to 10 c.c. of 0.5 per cent, 

 -diastase and 10 c.c. of 0.5 per cent, starch (a) 10 c.c. of distilled 

 water, (b) 10 c.c. of boiled filtered apple sap, and (c) 10 c.c. of 

 1 per 1,000,000 HgCU. Both (a) and (c) remained clear, and 

 the starch dissolved in 3| hours, whereas in (b) a white coagulum 

 of starch formed which was not entirely undissolved, even after 

 -3 days at 25° C. The clear supernatant liquid before shaking 

 gave no reaction with iodine, just as though all the starch had 

 been dissolved instead of merely the unprecipitated starch. 



Similar experiments with equal volumes of solutions of mercuric 

 •chloride, 0.2 per cent, malt diastase, and 0.5 per cent, starch, 

 showed that a 1 per 1,000,000 solution of mercuric chloride exer- 

 -cises no appreciable influence upon the diastase, whereas a 1 per 

 10,000 solution appeared to stop the diastatic action entirely. 



The pulp cells of apples are evidently much more sensitive to 

 mercuric chloride than is diastase or diastatic action. In bitter 

 pit formation, however, the arrest of diastatic action comes first, 

 and the death of the cell follows later. The diastase of apples is 

 either small in amount, or feeble in activity, as compared with 

 malt diastase, and the solution of the starch grains in ripening 

 apples may take not a few hours, but several weeks to complete, 

 so that a feeble diastatic activity might be sxippressed or retarded 

 by gradually accumulating traces of poison until the concentra- 

 tion was reached at which the protoplasm was killed. Under the 

 conditions of a laboratory experiment where the tests must be com- 

 pleted in a few hours to a day or so, and comparatively large 

 amounts of ferments used, the use of diastase would only detect 

 a ])(iison in tlie ash of bitter pit tissue when present in relatively 

 huge amount. It would not necessarily detect an amount of 

 poison sufficient to iidiibit a feeble diastatii' activity, taking nor- 

 mally days or weeks to be conq)leted. It is also conceivable that 

 an amount of jxiison insufficient to inhibit diastatic action, or to 



