214 Aso, Which Compound in certain plant-juices can liberate iodine etc. 



various efforts to remove this disturbing factor in the shoots 

 of beans in order to obtain the Griess reaction thus far have 

 failed. But, neverthless I am inclined to believe that nitrite 

 causes the iodine reaction also in other cases, not only in 

 Sagittaria. In those cases where it is by no means easy to 

 obtain the Griess reaction, while the iodine reaction is readily 

 observed, the diphenylamine reaction can sometimes be obtained 

 as e. g., with the shoots of potatoes. It is, however, necessary 

 to pour very carefully the plant juice on the surface of Knops 

 diphenylamine Solution. If the blue coloration does not appear 

 verry soon, then moderate shaking will produce the blue. However 

 it will rapidly disappear again. 



S u m m a r y. 



1. The view of Kastle and Loewenhart that the oxidi- 

 zing agencies in plant Juices are organic peroxids is not suffi- 

 ciently proved and not in accordance with my observations. 



2. There exists also no decisive proof that the liberation 

 of iodine from potassium iodid by certain plant Juices is due to 

 an organic peroxid. 



3. The common oxidase can not liberate iodine. The 

 liberation of iodine and the guaiac reactions do not show any 

 parallelism. 



4. The iodine reaction obtained with the buds of the 

 Sagittaria bulb is due to traces of nitrites, which thus were 

 shown the first time to occur in phaenogams. 



5. There occur in plants (bean shoots) certain benzene 

 Compounds that can prevent the reaction of Griess upon nitrites. 



vi 



