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EXPERIMENTAL METHOD. 



The method employed in the experiments here 

 reported is a modification of the methods already used 

 by Jentys, Kossowich, Kosaroff and Noyes in their stu- 

 dies of the effects of carbon dioxide and other gases 

 on plant roots. It will be remembered, as described 

 above for the experiments of Kosaroff, that this tech- 

 nique consists in sealing the r ots (with the soil in 

 which they lie) into a container through which the 

 desired gas can be passed. The stem of the plant pro- 

 jects through the seal so that the aerial portions are 

 exposed to the general atmosphere. In the experiments 

 of the investigators mentioned the duration of a sin- 

 gle experiment was never more than a few hours and for 

 such short times the technique offers no important dif- 

 ficulty. However, as noted in describing the results 

 of Kosaroff with hydrogen, such short-time experiments 

 are not adequate for the investigation of the nature of 

 root reppiration. It is probable that almost any plant 

 can endure anaerobic conditions for a short time. If 

 real anaerobic respiration of roots is to be realized 

 experimentally by this method, it must be possible to 

 grow plants for long periods with their roots in soil 

 which is sealed*off from the general atmosphere so that 

 the composition of it 3 own internal atmosphere may be 

 controlled. This necessity for experiments of longer 



