Aso, On the Nature of Oxidascs. 
321 
tassinm iodicl starcli reaction that is, the former is caused by 
oxidase very frequent in plantjuices, and the latter by nitrite 
which is present in certain plantjuices, as I had positively pro- 
ved in one case (1. c. page 212). 
But if tlie iodine liberation by certain plantjuices would be 
due always to traces of nitrite and not to enzyms, how is tlie 
fact to be explained that this property is lost in most cases 1 ) 
on heating? The probable answer is here that plantjuices are 
often slightly acid and contain at the same time small quanti- 
ties of amido-compounds. Under this condition traces of nitri- 
. tes must dissapear on warming, while after addition of some 
alkali, the reaktion will probably be maintained after boiling. 
About 15 c, c. of 0,001 o 0 potassium nitrite solution were 
mixed with an equal volume of 1 o 0 aspaihgine solution (aqueous) 
and divided into three equal parts. To one part, I added a 
drop of dilute acetic acid and to anotlier, a drop of dilute caustic 
potash free from nitrite while the tliird served as control. These 
Solutions were heated to boiling for tliree minutes then about 
1 c. c. of potassium iodid-starch solution was added and to the 
alkahne as well as the control Solutions also, some dilute acetic 
acid to render the reaction slightly acid; the result obtained was: 
O kJ 
Control 
Alkaline 
solution 
Acid 
solution 
' 
Distinctly 
Distinctly 
Xo reaction 
and 
and 
at ah. 
immediately 
immediately 
kJ 
This fest was repeated: 30 c. c. of 0,001 % potassium nitrite 
solution were mixed with 30 c, c. of 1 °/o asparagine solution and 
divided into three parts. To one was added a drop of dilute 
acetic acid, to the otlier a drop of dilute caustic potash solution 
while the third served as control. These Solutions were kept 
boiling for live minutes and tested with potassium iodid-starch 
as above-mentioned with tlie fohowing result: 
Control 
Alkaline 
solution 
Acid 
solution 
The reaction appeared, 
Distinctly 
no reaction 
but slower and weaker 
and 
at all after 
than in the alkaline liquid 
immediately 
several hours. 
b Once. I groimd four buds of Sagittaria with 20 c. c. water. The 
pressed jiiice which produced strong reaction with gnaiac tincture, Griess 
reagent as well as potassium iodid-starch was divided into two halves and 
one was boiled for one minute while the other served as control. Both 
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