



2IO 



BOTANICAL GAZETTE 



[march 



many 



succumb 



to attacks of fungi or of insects. He believes these 

 secondary causes are often blamed for the total injury. 



Rather striking formative effects have been noted by a number 

 of writers. Stone observed abnormal tissue in the cortex of stems 

 of Carolina poplar, proliferation tissue in the lenticels of willow, 

 and increased root development in cuttings of the willow exposed 

 to gas. Harvey and Rose (6) found that gas and ethylene cause 

 tubercle-like growths on roots of Catalpa and Ailanthus. 



Methods 



The gas used in this investigation was that of the Peoples Gas 



Company 



It averages about 4 per 

 n monoxide. The ethyl- 



from 



monox 



phuric acid and washed in the usual way. It contained 90 per 

 cent ethylene and 10 per cent air impurities, 

 ide was generated from oxalic 

 acid, washed and analyzed. E; 



acid and concentrated sulphuric 

 ch of these was mixed with air to 



same volume nercentaee as exists in illuminatin 



mixtures 



the illuminatin 



& 



and the air-gas 

 gas. 



Three general methods of exposing plants to gas were used: 

 (1) the flowers only were treated with gas; (2) potted plants were 

 sealed in wardian cases and measured amounts of gas added; and 

 (3) root systems were treated with a slow stream of gas in the 

 soil. 



1. To determine the limit of toxicity for the flower of the calla 

 lily (Zantedeschia ethiopicd) the method employed by Crocker 

 and Knight (i) upon carnations was used. A 20 liter carboy was 

 inverted over the flower bud and a rubber stopper fitted about 

 the petiole and made gas-tight with vaseline. Gas was forced 

 into this 20 liter bottle through a tube inserted in a second hole 

 in the stopper. A measured amount (800 cc. or 4 per cent) of illu- 

 minating gas was forced in, and the pinchcock closed. A control 

 plant was put under identical conditions, except that no gas was 

 used. When the bottles were removed 11 days later, both flowers 











