1908] CROCKER AND KNIGHT— CARNATIONS 269 



to determine the toxic limits of methane, carbon monoxid, acetylene, 

 hydrogen, carbon bisulfid, and benzene to the buds and flowers. 

 As would be expected, hydrogen was perfectly neutral when it com- 

 pletely displaced the nitrogen of the air. In all the other constit- 

 uents here mentioned, the toxicity was such that in the least amount 

 of illuminating gas necessary to kill the bud no one is concentrated 

 enough to reach 5V of its toxic limit. It is very probable, therefore, 

 that these constituents play no part in determining the toxic limit 

 of illuminating gas. It has already been stated that the absorption 

 of hydrogen sulfid and sulfur dioxid does not modify the toxicity of the 

 gas. This leaves, then, ethylene, the higher homologues of ethylene 

 and acetylene, and certain aromatic sulfur compounds to account for 

 the toxicity of the gas. All these substances except ethylene exist 

 in very small percentages in illuminating gas. All evidence in the 

 following experiments also points to the conclusion that there is 

 enough ethylene in the gas to account for its toxicity. 



The small greenhouse in which entire potted plants were exposed 

 to the action of gas had a capacity of 1 . 6c) cu - m . In order to make 

 comparisons easy between buds of the same size on the plants exposed 

 and on the checks, corresponding buds were tagged with the same 

 numbers. We need describe only one of these experiments. Potted 

 plants of the Boston Market were put into the small greenhouse in 

 the evening and 2 liters of gas were run in at the end opposite the 

 plants, allowing a gradual distribution by diffusion. The plants 

 were taken out the next morning to prevent injury by high tempera- 

 ture. The following evening the plants were returned to the enclos- 

 ure and left for 60 hours (the following two days being cloudy). At 

 the time they were put in, 4 liters of gas were run in, and the same 

 amount was added 48 hours later, there being at that time no per- 

 ceptible smell of gas in the chamber. This experiment served to 

 show (1) that the vegetation is far less sensitive to gas injury than the 

 buds, for there was no apparent injury to the vegetation; (2) plants 

 remained vigorous, put out new buds, and later produced other flowers. 

 The oldest buds (those showing color and just ready to open) and the 

 youngest buds (those less than o. 6 cm in diameter) were the ones most 

 injured. Many of the medium-sized buds, however, escaped death, 

 although retarded considerably in their growth. The older buds 



