252 
WILLIAM J. ROBBINS 
alkaline to methyl orange and acid to phenolphthalein. The deter- 
minations were made each time a culture solution was analyzed. 
Sherman and Thomas (191 5), working with a purified starch and a 
carefully prepared diastase, find an acceleration with NaCl, KCl, 
NaNOs, Na2S04, NaH2P04, and KH2PO4 and state: ''In our experi- 
ments it has been observed that as long as commercial starch, even 
of high grade, was used as a substrate, the smaller additions of the 
salts above mentioned have very little effect . . . ." It is therefore 
justifiable to assert that the chlorides and the sulphates of potassium, 
sodium, calcium and magnesium in M/ioo,ooo and M/io,ooo con- 
centrations in distilled water treated with carbon black decrease the 
secretion of diastase. What the significance is of the fact that the 
potassium salts decrease the secretion more than do the sodium salts 
of the same acid radical, cannot be stated. 
The fact that the addition of these salts to distilled water decreases 
the secretion of the enzyme diastase would seem to bear directly on 
the problem of the effect of distilled water on the growth of plants. 
It is of interest to note in this connection that Merrill (1915) has 
recently found that boiling the distilled water in which the roots of 
seedlings have been immersed decreases its toxicity. The effect of 
the boiling has been ascribed by Merrill to a destruction of bacteria. 
It would seem possible that it might be due to the destruction of 
harmful enzymes or thermolabile toxines secreted in larger quantity 
in distilled water. 
The conclusions reached by True (1914) on the leaching effect of 
distilled water on the roots of seedlings of Lupinus alhus and the 
protective action of CaCU on the growth of the roots also seem of 
particular interest. True concludes that in the presence of CaClo 
the dissociating power of the distilled water over the proteids and 
other chemical mechanisms of the cell is largely undeveloped, and the 
chemical integrity of the cell is protected in some way unknown. 
Similarly it might be postulated that the salts used here prevent the 
separation of the enzyme from a union with the protoplasm. It 
should be stated, however, that True and Bartlett (1915) report that 
solutions of KH2PO4 and KCl act essentially like distilled water. 
It has been noted that the phosphates of potassium and sodium* 
do not inhibit the digestion, and that greatly increased digestion is 
obtained with the addition of the nitrates to solutions of starch in 
distilled water treated with carbon black. This might lend some 
