2i, 



-lT- 



It is apparent that there was a complete cessation 

 of water-intake by the plant on July 28th, and, "by referring 

 to the history as cited above, it is seen that this is 

 just 3 days after the soil atmosphere was replaced by ni- 

 trogen. This cessation of water-intake was accompanied, 

 also, by slight visible wilting of the plant although severe 

 wilting did not occur until several days later. The varia* 

 tions of water-intake prior to its complete cessation on 

 July 28th may be due either to spontaneous variations in 

 the transpiring power of the plant or to some failure 

 of complete equivalence between the water-intake by the 

 plant and the water-loss from the reservoir, caused, per- 

 haps, by the occasional irregularities in the hour of 

 reading the water-loss. Whatever be the cause of these 

 variations they are unimportant since they are much less 

 marked than the complete cessation of water-intake on July 

 2 8th. 



These two symptoms, the cessation of water-intake 

 and the appearance of visible wilting, are the invariable 

 sequentia of replacing ty nitrogen the oirygen- containing 

 atmosphere about the roots of Coleus. If the removal 

 of the o:cygen is permanent the wilting and cessation of 

 water-intake are followed in a few weeks by the death of 

 the plant, ilowever, if air or osygen be forced through 

 the soil after the symptoms of injury have occurred but 

 before the plant is dead, the plant usually recovers, al- 

 though the recovery is slow and not always complete. The 



