STARCH-CONVERTING PowER oF TAKA DYIASTASE 57 
Some rather interesting results were obtained in a preliminary 
series of experiments. It was found that, the amounts of starch 
and diastase being constant, the converting power of the enzyme 
became more and more rapid with the concentration of the solution 
of starch, or starch paste. The solutions of starch varied from 3 
per cent., which is rather viscous, to 0.5 per cent., which is very 
watery. For determination of the sugar present, all were diluted 
to 0.5 per cent. to make the physical conditions exactly the same ; 
they were then heated rapidly in an autoclave to 110° C., to 
destroy the enzyme, and finally the relative amounts of sugar in 
the different bottles were determined volumetrically by means of 
Fehling’s copper-alkaline-tartrate solution. In each determination, 
2 c.c. of the freshly mixed standard was used, diluted to one half 
concentration, and the solution in question was added drop by 
drop to the boiling copper solution until the copper was com- 
pletely precipitated. The end reaction was tested with potassium 
ferrocyanide in the presence of acetic acid. The relative amounts 
of sugar in the different solutions can be very accurately deter- 
mined in this way, the amount of sugar in each bottle varying 
inversely as the amount of the solution necessary to cause com- 
plete precipitation. 
Table I shows in detail the variations in speed of starch trans- 
formation due to dilution. The ordinates represent the number 
of. cubic centimeters necessary to reduce 2 c.c. of Fehling’s solu- 
tion, and the first four abscissae represent the four different per 
cents. of starch experimented with. Thus the line starting ' 
the seventh ordinate and 3 per cent. abscissa shows that 7 c.c. 0 
the 3 per cent. starch solution were necessary to reduce 2 CC, OF 
Fehling’s solution; of the 1.5 per cent. starch solution, 8.8 c.c. 
were necessary, etc. . f 
As Duclaux* has carefully worked out, the conversion 0 
starch into sugar is most rapid soon after action begins, and de- 
creases slowly at first, then more and more rapidly until most of 
the starch is converted and action ceases. 
The last six abscissae in Table I show my results. 
abscissae represent the number of hours the enzyme was allowed 
to act before determination. 
Here the 
* Duclaux, Annales de I’ Institut Pasteur, 12: 96. 
