rvH 



Two of these plants, after recovery from the 

 first application of nitrogen were again supplied with 

 this gas in place of oxygen. These were plants number 

 3 and number 201. In both cases the same symptoms of 

 injury recurred; in number 3 after 7 da£s, and in number 

 201 after 4 days. To one plant (not included in t 

 above table) nitrogen was applied for only one day, being 

 then replaced by air. There was no apparent injury and 

 no cessation of water-intake. The plant continued to 

 grow normally. To five plants oxygen was applied as in 

 the usual gas bag technique, neither injury nor bene- 

 fit was perceptible. To two plants ordinary air was 

 applied, but in closed gas bags according to the usual 

 technique. One of these plants was uninjured after 50 

 days when the experiment was stopped. The other plant 

 wilted after 12 days and ultimately died. To one plant 

 the seal about the stem was applied as usual but the tin 

 top to the can was omitted, leaving the soil exposed to 

 the air. This plant grew normally and showed no injury. 

 In two cases injury occurred after sealing but with the 

 gas outlet tubes still open to the air, the times of 

 appearance of wilting being, respectively, 13 and 17 

 days after sealing. In both cases the symptoms of in- 

 jury were exactly as described above, the intake of water 

 ceasing after 11 and 7 days, respectively. 



