

220 BOTANICAL GAZETTE [march 



When the trees were treated in the open ground, glass tubes 

 12-24 inches long, depending upon the size of the trees, were buried 

 close to the side of the tree. ' The same precaution was used here 



to prevent clogging. 



The following are the results for each tree or plant treated, 

 the length of time treated, and the amount of illuminating gas 

 passed into the soil. In no case could the odor of the gas be 

 detected on a handful of the soil or escaping in the air. The 

 temperature range was 12-20 C. 



Acer Negundo. — A young tree was treated for 45 days and given 

 60 liters of gas. There was no visible effect above or below ground. 



Acer saccharinum.- — Treated 42 days and given 140 liters of 

 gas, the parts above ground were unchanged. The stem below 

 ground, however, was swollen, soft, and cracked longitudinally. 

 A section showed proliferation tissue produced just outside the 

 vascular cylinder^ 



Chrysanthemum hortorum. — One plant, being treated 42 days 

 and given 80 liters of gas, was killed, no proliferation tissue being 

 produced or other visible changes. A second plant was treated 28 

 days and given 60 liters of gas. Some roots grew up out of the 

 ground, probably due to loss of geotropic response. 



Fraxinus americana. — Treated for 42 days and given 120 liters 

 of gas, the parts above ground were unchanged. Below ground 

 the stem was swollen, soft, and cracked longitudinally. Sections 

 showed that abundant proliferation tissue was produced just out- 

 side the vascular system. 



Grevillea robusta. — One specimen was treated 33 days and given 

 40 liters of gas. After 2 weeks gummy matter exuded from a slight 

 crack in the stem just above the ground. A second plant was 

 treated 48 days and given 40 liters of gas; and a third was treated 

 31 days and given 19 liters of gas. The roots of all three showed 

 spongy white masses of tissue at short intervals, with no epidermis. 

 Many roots were dead. The underground parts of the stem were 

 swollen, due to the development of spongy, white tissue. 



Hibiscus rosa-sinensis. — A plant was treated 15 days and given 

 40 liters of gas. The leaves showed epinasty for 2 days and then 

 fell off. After 4 days' treatment, white spongy tissue developed 









