1917] 



DO UB T—ILL UMINA TING GA S 



213 



caused the oldest leaves at the base of the stem to fall off and the 

 younger leaves showed epinasty; 100, 50, and 25 ppm still caused 

 marked epinasty. With ethylene, 5 ppm caused some leaf fall, 



marked, and some petioles showed a com 



coil (figs. 3, 4); 2 ppm 

 o . 1 ppm still caused e 

 12.5 ppm caused no res 



o . 2 and 



W 



r 



1 



2 



Figs, i, 2. — Fig. 1, Lycopersicum esculent urn: plant at left has been treated for 

 12 hours with 50 ppm carbon monoxide; plant at right has been treated for 12 hours 

 with 8 ppm ethylene; the former appears perfectly normal, while the latter shows the 

 distinct epinastic response characteristic of gas poisoning; note spiral coiling of one 

 petiole; fig. 2, Lycopersicum esculentum: control at left; plant at right has stood for 



1000 ppm illuminating 



a few hours longer 



would cause leaf fall, but as they stand the leaves show strong epinastic response; 



down 



Mimosa pudica. 2 — With illuminating gas, 60,000 ppm caused 



lm 



ppm 



vinal 



movement; after a day the leaflets turned yellow and fell 

 off; then some petioles fell; some of the youngest leaves were 



2 With Mimosa all amounts of gas used caused the plants to lose their sensitive- 

 touch. After recovery they regained it. 



3 The leaflets folded and the leaves drooped as they do at night or after stimu- 

 lation, but recover}- was complete after removal. 



ness 



