1909] SCHREINER & REED— OXIDIZING POWER OF ROOTS 383 



From these results it can only be concluded that a slightly alkaline 

 medium is most favorable for this peroxidase reaction. It will be 

 remembered that Wollny 37 found also that the oxidation processes 

 in the soil were distinctly favored by slightly alkaline conditions. 



The effect of putrefactive processes upon oxidation is another 

 question which was briefly investigated. When a number of seedlings 

 were placed without any support in water containing aloin (the 

 entire root system, seed, and lower part of the plant, being thus sub- 

 merged), it has been observed that the red color first produced 

 subsequently disappeared. An experiment was accordingly planned 

 to learn whether oxidation phenomena would be affected when the 

 seeds were submerged and gave rise to products of putrefaction. 



Twelve cultures of wheat plants were prepared and allowed to grow 

 four days in tap water. In one-third of the cultures the seedlings 

 were adjusted in the notched corks so that only the root systems of 

 the plants were submerged; in one-third of the cultures the seedlings 

 were lowered so that the seeds also were submerged, and one-third 

 had the seedlings entirely submerged. On the fourth day ioo rag 

 of aloin were added to each culture jar, and they were examined 

 twenty-four hours later with reference to the production of colors. 

 It was found that the cultures planted with only the root systems 

 submerged showed a very considerable amount of oxidation, but in 

 those where the seeds or entire plants were submerged there was none 

 of the red color produced by oxidation. In these cultures where no 

 oxidation was shown, there were putrefactive processes at work, a 



mean 



w hen putrefactive processes occur. Whether this inhibition of oxida- 

 tion is caused by the products of putrefaction or by a perverted 

 metabolism, since the plant must function under somewhat anaerobic 



conditions, remains undecided. 



That the oxidizing power of the plant was not destroyed is shown 

 b y the fact that by raising the seeds out of the culture water and 

 refilling the jars with fresh tap water containing aloin, the character- 



lst 'c oxidation occurred. f 



The foregoing experiments raised a question as to the amount ot 



Heidelberg. 



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