



218 BOTANICAL GAZETTE [march 



Hyacinthus (several varieties). — With the same quantities of 

 illuminating gas, the responses were identical with those of the 

 tulip. 



Carica Papaya. — With illuminating gas, 20,000 ppm caused the 

 older leaves to fall and the younger leaves to show epinasty. 



Caladium esculentum. — This showed no response with 75 ppm 

 illuminating gas, 8 ppm ethylene, or 50 ppm carbon monoxide. 



Lupinus perennis. — This showed no response with 8 ppm 

 ethylene or 50 ppm carbon monoxide. 



Eriobotrya japonica, Phoenix canariensis, Conocephalus sp., 

 Canna (King Humbert and other varieties), Achyranthes Lindini, 

 Cytisus canariensis, and Alternant her a sp. showed no response with 

 20,000 ppm illuminating gas. 



Poly podium, Aspidium, and Asplenium. — With illuminating 

 gas, 60,000, 8000, and 4000 ppm caused no response. 



The preceding data are summarized briefly in table I. The 

 plants are grouped according to their sensitiveness to gas: very 

 sensitive, less sensitive, and resistant. The minimum concentra- 

 tion necessary to produce a response is given in each case. 



The following plants showed no response to illuminating gas 

 or to ethylene in the concentration used: Caladium esculentum, 

 Lupinus perennis, Eriobotrya japonica, Phoenix canariensis, Con- 

 ocephalus, sp., Canna, Achyranthes Lindini, Alternanthera sp., 

 Cytisus canariensis Poly podium, Aspidium, and Asplenium. 



Root treatment of trees 



Two or three year old trees were used for the root treatment. 

 They were treated in flower pots during the winter and early spring, 

 and then the work was carried on out of doors upon young trees 

 which had been growing in the soil for a year or more. 



The potted plants were set on tripods and glass tubing was run 

 through the cork plug in the bottom of the pot. Connection was 

 made with a wash bottle and the rate of gas flow through this 

 wash bottle was controlled by means of a brass stopcock. The 

 gas was forced out from the inverted carboys by means of water 

 from a raised tank. All rubber connections with glass tubing were 

 as short as possible, gas tight, and the gas w r as "water sealed" in 









