Upon STARCH-CONVERTING PowER OF TAKA DIASTASE 59 
The transformation was allowed to proceed until the check. so- 
lutions were a little more than half converted into sugar ; this cor- 
responds to about the fourth ordinate in the tables. 
The chemical agents used are given in fractions of the normal, 
The normal solution was made by dissolving as many grams of 
the salt as correspond to its molecular weight in less than one 
liter of the sterile 1 per cent. starch paste, and the solution then 
made up to exactly 1,000 c.c. by the addition of the starch paste. 
The chemical agents experimented with fall naturally into four 
classes—the mineral acids and organic acids, the salts of these 
acids, the alkalies, and the metals. 
It will not be attempted to give a complete summation of lit- 
erature, but such will be cited as seem to bear directly on the sub- 
ject. 
It has been noted by Baranetsky,* Chittenden & Griswold,t 
and Effront ¢ that strong solutions of mineral acids destroy diastase 
and weak ones accelerate its action. Cohnheim § records no effect 
for moderate concentrations of HCI, and Langley & Eves || report 
that ‘the slightest trace’ (0.015 per cent., about ”/240) of HCl 
is very injurious. 
Table II shows the results of my work. In this table, as in all 
following, the abscissae represent the strengths of the chemical 
agents and the ordinates represent the amount of the solution 
tested necessary to reduce 2 c.c. of Fehling’s solution. “Trace” 
means that so slight an amount of sugar was present that oves 
15 c.c. of the solution would be necessary to reduce the Fehling’s 
solution. : 
At a concentration of /to all the acids completely checked 
enzymetic action. At ~/100 chromic acid gave complete inhibi- 
tion; the other mineral acids allowed a slight action at 7/100 and 
gave a marked acceleration at a dilution of 2/1000. Sulphuric 
acid gave the most marked results, the amount of sugar produced 
being almost double that of the check. Chromic acid still gave a 
(Leipzig, 1876.) 
* Baranetsky, Die Starkeumbildenden Fermente inden Pflanzen. 
¢ Chittenden & Griswold, American.Chemical Journal, 3: 205. 
t Effront, Comptes Rendus, 115 : 1324- Meee: 
4Cohnheim, Archiv fiir Pathologie, Anatomie und Physiologie ( Virchow), 28: 
241. 
| Langley & Eves, Journal of Physiology, 4: 18. 
