io8 
Journal of Agricultural Research 
Vol. V, No. 3 
(6) A quantity of concentrated apple juice prepared by Gore (6) by 
his freezing method was secured and used in some of the tests, since 
it was thought that this process would be likely to leave the enzyms 
uninjured in the juice. 
examination of different preparations for enzyms 
In the earlier examinations reported below, several different prepara¬ 
tions were examined simultaneously for the particular type of enzym 
which was being sought, in order to avoid any wrong conclusion from 
improperly prepared material. Experience soon showed, however, that 
either the acetone-dried powder or the pulp ground with quartz sand 
would yield active extracts in every case where activity could be found 
in material prepared by any of the above methods, and one or the other 
of these two preparations was used in all the later tests. The acetone- 
dried powder has the advantage that a considerable quantity of material 
can be prepared at one time for subsequent examination. 
diastases 
Diastases have been shown by Thatcher and Koch (n) to be readily 
diffusible into water surrounding cell tissues. It seemed probable, there¬ 
fore, that if enzyms of this type were present in apple flesh they would 
appear in juice expressed from pulp after thorough rasping. Samples 
of clear juice by decantation were secured from three different varieties 
of apples and tested for diastatic activity. Four separate mixtures 
were prepared for each variety of juice. The first contained io c. c. of 
a io per cent solution of soluble starch prepared by the Lintner method 
(5), 10 c. c. of the juice in question, and 10 c. c. of distilled water. The 
second contained 10 c. c. of soluble starch, 10 c. c. of the juice which had 
been boiled for 10 minutes and made to its original volume with water, 
and 10 c. c. of distilled water. The third contained 10 c. c. of soluble 
starch, 10 c. c. of the unboiled juice, sufficient N/10 sodium hydroxid 
(NaOH) to exactly neutralize the juice used (determined by a preliminary 
titration, using phenolphthalein as indicator), and enough distilled water 
to make the total volume 30 c. c. The fourth, or control, contained 10 c. c. 
of soluble starch and 20 c. c. of distilled water. The contents of each flask 
were thoroughly mixed and an aliquot drawn off for the determination 
of reducing sugars present in the solution. The flasks containing the 
remainder of the solution were then placed in an incubator for 30 min¬ 
utes at 40° C., these being the conditions recommended by Sherman, 
Kendall, and Clarke (10) for all determinations of diastatic activity. 
At the expiration of this period action was stopped by adding sufficient 
N/10 sulphuric acid to make the total volume a N/200 solution, and an 
aliquot equal to that taken before the digestion was drawn off for the 
determination of its reducing sugar content. The soluble proteins were 
precipitated and the reducing sugars determined by the method out- 
