

214 BOTANICAL GAZETTE [march 



uninjured. With ethylene, 8 and 5 ppm caused the same response 



as the preceding; 2 ppm caused some leaf fall but the injury was less; 



0.2 ppm resulted in the fall of a few leaflets, but all leaves showed 



sensitiveness by folding together; 0.1 ppm caused some leaflets [ 



to fall. With carbon monoxide, 50 ppm caused a clear response; 



leaflets folded and petioles drooped ; no leaflets fell ; the plant lost 



its sensitiveness to touch; recovery was complete after two days 



in air. 





Ricinus communis* — With illuminating gas, 60,000 ppm caused 

 imperfect rigor, some leaves falling; 100 ppm caused falling of the 

 older leaves and epinasty of all others; 50 ppm caused marked 

 epinasty but no leaf fall. With ethylene, 8 and 5 ppm caused most 

 of the leaves to fall, the youngest showing epinasty; 2 ppm caused 

 no leaf to fall, but all the leaves showed epinasty; 0.2 and 0.1 

 ppm caused a less marked response, but epinasty was still evident 

 (fig. 5). With carbon monoxide, 50 and 12.5 ppm caused no 

 response. 



Datura Stramonium. — With illuminating gas, 60,000 ppm caused 

 partial rigor; 4000 ppm caused all the leaves except the youngest * 



to fall; 500 ppm caused falling of the oldest leaves; epinasty of 

 the younger leaves was very similar to that of Ricinus; 50 ppm 

 caused epinasty of the older leaves. With ethylene, 8 ppm caused 

 the older leaves to fall, the younger leaves showing epinasty; 

 5 ppm caused less leaf fall, but the remaining leaves showed epi- 

 nasty; with 2 ppm there was no leaf fall, but evident epina§ty; 

 with o . 2 and o . 1 ppm there was evident epinasty. With carbon 

 monoxide, 50 ppm gave no visible response. 



Lycopersicum esculentum. — With illuminating gas, 35.000 ppm 

 caused the older leaves to fall, the root growth was stimulated on 

 the stem above the ground, and epinasty occurred; 5 26,000, 1000, 



« The epinastic response is very striking in this plant. The cotyledons, leaf blades, 

 and petioles, all show the characteristic turning. The petioles droop about 90 from 

 their normal position, so that instead of making an angle of about 45 with the stem 

 above the leaf, they droop until they make an angle of about 45 with the stem below 

 the leaf. The blades and petioles are rigid after turning, and usually recover their 

 normal position after a couple of weeks with no gas present (fig. 5). 



* On the older leaves this was near the blade; on the younger leaves it was near 

 the stem. In some cases this growth caused a spiral coil of the petiole (fig. 1). 



