Experiments on Plants 797 



2. Vegetation. 



Experiments on vegetation are very hard to perform, as is 

 easily understood, because of the small size of the glass receivers 

 and their lack of transparency. Yet here are a few which are suf- 

 ficiently conclusive. 



Experiment CCCLXXXIII. April 28. Barley sprouted 10 to 12 cm. 

 high in the large Seltzer water receivers (2 liters). 



A, which is in the receiver with a wire jacket, is closed and left 

 at normal pressure. 



B, in a receiver without a jacket, which lets more light through, 

 is taken to 3 superoxygenated atmospheres, changed tv/ice a day. 



May 7. In A, the sprouts have more than doubled their length; B 

 has not changed: left in open air, the stalks turn yellow and die. 



Experiment CCCLXXXIV. July 25. Little sensitive plants 6 to 8 

 cm. high, healthy, in a pot. 



A. Placed, in the pot, in a receiver of 1 liter, with wire mesh 

 jacket; left at normal pressure, well corked. 



B. Another pot in a similar receiver, without the wire mesh 

 jacket, and consequently under better lighting conditions. Carried to 

 6 atmospheres of air. 



By evening B has lost sensitivity. 

 July 26. The leaves in B are falling. 

 July 27. B completely dead; A healthy. 



Experiment CCCLXXXV. August 1. Sensitive plants like those in 

 the preceding experiment. Same receivers. 



A. At 3 atmospheres. 



B. Under normal pressure. 

 August 5. Both sensitive and healthy. 



Experiment CCCLXXXVI. July 25. Small sensitive plants, quite 

 sensitive. 



A. Cylindrical apparatus at 4 atmospheres with 80% of oxygen; 

 tension 320, equivalent to nearly 16 atmospheres of air. 



B. Normal pressure, air. 



July 27. A, dead; B quite sensitive. 



So sensitive plants die quickly at 6 atmospheres of air, and it 

 is more than probable that the other green plants would die at the 

 same pressure, although much less rapidly. Plants, therefore, seem 

 to dread excessive oxygen tension still more than animals, even 

 warm-blooded animals. 



