768 



Hall, Miller, and Herrero 



Table 6. Chromatographic characteristics of the radioactive tryptophan-like me- 

 tabolite from cotton leaves. 



.Sohent System 



Butanol:acetic acid:water (100:22:50). . . 



Ethanol:butanol:water (4:1:1) 



Methanol :ammonia:vvater (80:5:15). . . . 



77 per cent Ethanol 



70 per cent Isopropanol with NHj atmos, 



Butanol:pyridino:water (1:1:1) 



Butanol:acetic acid:water (60:15:25). . . . 



Isopropanol :NH3:H20 (8:1:1) 



Isopropanol:NH3:H20 (20:1:2) 



Isopropanol :NH3:H20 (80:5:15) 



Rf \'alues 



I 



Tryptophan 



0.51 

 0.35 

 0.65 

 0.37 

 0.82 

 0.52 

 0.55 

 0.50 

 0.24 

 0.44 



The results obtained shed additional light on the hormonal nature 

 of ethylene. Quantitative evidence that ethylene is produced naturally 

 by plants (5, 13, 19), that it is translocated and metabolized, and that 

 it affects the basic reactions of plants (16, 17, 20) supports Crocker's 

 contention (8) that ethylene shoidd be classed as a phytohormone. 



It is apparent from the data that ethylene is absorbed readily by 

 the vegetative organs of the plant. The accumulation of radioactive 

 carbon from ethylene apparently reached a maximum about two hrs. 

 after administration. The amount absorbed increases with the dosage 

 administered and is greatly influenced by the physiological activity 

 of the plant or tissue and whether "fresh" or "aged" ethylene is used. 

 Comparatively, only a small amount of "fresh" ethylene was fixed by 

 Colciis or cotton plants. The changes occurring dining the "aging" 

 of ethylene are presently unknown. Based on field observations (13) 

 apparently similar changes occur in ethylene that increase its reac- 

 tivity for plants wiien it is exposed to atmospheric conditions. 



Ethylene was absorbed in higher amounts in the dark than in the 

 light under aerobic conditions and with lowered carbon dioxide con- 

 tent of the surrounding atmosphere. A large amount of the ethylene 

 absorbed is unreacted or in loose combination in the plant since two- 



