710 . REPORT—1899. 
maintained by different authors that acids favour the saccharification of starch by 
diastase. 
My experiments have led me to a different conclusion. The slightest trace of 
Free acid distinctly retards the action of diastase on gelatinised as well as on soluble 
starch; this applies to all acids. The action is, however, apparent only if both the 
starch employed and the solution of diastase are absolutely free from salts on which 
the added acid may act. 
If the solution contains such salts, among which the most important are 
secondary phosphates, which are distinctly unfavourable to diastatic action, the 
addition of acid is favourable as long as there is no excess over the quantity neces- 
sary to transform these salts into primary phosphates. In that case the acidity of 
the liquid increases by addition of acid, but there is no free acid present as long as 
the whole of the secondary salt is not decomposed. The unfavourable action of 
acid appears as soon as the quantity added is greater than that required for this 
decomposition. 
A distinction must therefore be made between acidity and free acid, as is 
proved by the influence of primary phosphates or diastatic action, which salts, 
although having an acid reaction, are distinctly favourable. This influence of 
phosphates seems to be specific for salts of this kind. 
The same influence of phosphates may be noticed with enzymes other than 
diastase, and I am at present engaged in investigating this subject farther in con- 
junction with L. Hubert. 
3. Note on the Combined Action of Diastase and Yeast on Starch-granules. 
By G. Harris Morris, PA.D., FDC. 
It has long been known that when yeast is allowed to act on a solution of 
atarch-transformation products in the presence of active diastase, the quantity of © 
matter fermented is far in excess of that which can be fermented by the yeast 
alone; and, furthermore, that when active diastase and yeast are allowed to con- 
jointly act on the so-called stable dextrin, which, under ordinary conditions, is 
neither degradable by diastase nor fermentable by yeast, it is entirely fermented. 
The action is apparently analogous to that of symbiosis, only, in place of two living 
organisms being concerned, we have a conjunction of an unorganised enzyme, 
diastase, and the yeast organism. 
Some experiments I was led to make a few years ago showed that a similar 
action takes place when ungelatinised intact starch granules are submitted to the 
joint action of diastase and yeast. The experiments were made with barley 
starch, and were briefly as follows :— 
A quantity of the dry starch was shaken continuously with a mixture of cold- 
water malt extract and water for seventy-two hours. 
A similar mixture was made with the addition of a small quantity of yeast, 
and allowed to stand side by side with the above for the same length of time. 
An examination of the two then showed that in the first experiment 22:2 per 
cent. of the starch had gone into solution, whilst in the second 51°8 per cent. had 
disappeared. In the former the starch had been converted into maltose, and was 
found in the solution ; in the latter, the maltose first formed had been to a very 
large extent fermented, and existed as alcohol. 
It appeared possible that the increased action, when yeast was present, was due 
to the removal of the soluble product—maltose—from the field of action, thus 
allowing the diastase to exert a greater activity. In order to determine this, 
another experiment was made, and two bottles, one containing a mixture of starch, 
malt extract, and water, the other a mixture of starch, malt extract, and solution 
of starch transformation-products, were shaken side by side for the same length of 
time. In each case the amount of starch dissolved was practically identical, thus 
showing that the soluble products had no retarding action on the diastatic action. 
Another experiment in which the product of the action of the diastase was 
removed by dialysis, instead of by fermentation, gave a similar result—the sum of 
