310 ARCH E. COLE 



in its body. Whether the production of an oxidizing agent is 

 absolutely dependent upon the presence of molecular oxygen 

 remains to be proven. 



4. Liberation of oxygen from decomposing plants 



It was noticed during the experiments just described that 

 when oxygen was removed from the expermiental chamber, 

 although none of the chironomid tissue or chitin was able to 

 oxidize the guaiacum, some of the plant debris in the mud did 

 so. Such an oxidation would be a normal reaction in living 

 chlorophjdl-bearing plants, but for dead and partially broken- 

 down plant fragments, it was considered to be rather unusual. 

 It was thought that perhaps a few of the cells still contained 

 functional chloroplasts which were carrying on photosynthesis 

 in the presence of light, and so were giving off oxygen in the 

 atomic form which was oxidizing the guaiacum. 



To ascertain whether this was the case, a series of experi- 

 ments were carried out similar to those cited on page 308 (also 

 Appendix, p. 320). The experiments differed from those pre- 

 ceding, in that mud, containing decaying plant tissues, was used 

 instead of the extract of chironomid larvae, and the experiments 

 were carried out in darkness, the object being to find out if the 

 plant debris was capable of oxidizing guaiacum in darkness as 

 well as in the absence of molecular oxygen. One of a series of 

 experiments was allowed to continue for twenty-four hours 

 before guaiacum was added (benzidine was sometimes used and 

 results were the same as with guaiacum). Light was then 

 emitted in order to observe the reaction, and it was found that 

 the plant tissues had turned blue on their surfaces, indicating 

 the oxidation of guaiacum. 



These experiments indicate that some process either in the 

 decomposition of plants or in the bacterial action in conection 

 with decaying plant tissues was producing an oxidizing agent 

 capable of oxidizing guaiacum or benzidine. This reaction is 

 independent of the presence of light and of molecular oxygen. 

 Neither light nor detectable molecular oxj'gen are present at the 



