studies With C^''-labeled Ethylene 111 



chondria, yet they do undergo swelling in the presence of ethylene. 

 Although we were not able to demonstrate any significant effect of 

 ethylene upon oxidative phosphorylation, ethylene does affect mi- 

 tochondria in a physical manner. 



Dr. Bitancourt: I want to refer briefly to some experiments carried 

 out several years ago with Miss Rossetti. We worked with the fungus, 

 Mucor spinosus, which produces a gas which stimulates the growth 

 of Phytophthora. When the air above cultures of Mucor spinosus was 

 passed through water, sulfuric acid, or sodium hydroxide before pass- 

 ing over cultures of Phytophthora, growth stimulation still occurred. 

 The gas produced by Mucor spinosus did not induce epinasty in 

 tomato plants. 



Dr. Ray: I, too, am a bit disturbed by the "aging" effect. I wonder 

 ^vhether even the original samples of ethylene contain trace amounts 

 of this material derived by aging. It causes one to doubt whether any 

 of the "metabolites" (so-called) of ethylene which are observed are in 

 fact derived from ethylene and not from this other material since it 

 apparently is fixed so much more readily by the plant. I also won- 

 dered whether you had thought of trying to wash the ethylene through 

 towers of alkali, acid, or adsorbents of various kinds to see whether 

 this couldn't be gotten rid of. I think this is a rather basic problem. 

 Even the initial samples could be contaminated with trace amounts, 

 could they not? 



Dr. Hall: Yes, even a fresh sample of radioactive ethylene may 

 have trace amounts of ethylene oxide present, but the content of 

 ethylene oxide does not increase with age nor is ethylene oxide respon- 

 sible for the increased reactivity of the "aged" sample. Scrubbing of 

 the "aged" ethylene as you propose does not decrease its enhanced 

 reactivity over that of fresh ethylene. Also in experiments where we 

 have used both fresh and "aged" ethylene, we found essentially the 

 same metabolites being formed after absorption, but much higher 

 activity in the metabolites from the "aged" sample. To date we have 

 not been able to show by gas chromatography and the vibrating reed 

 electrometer that any other radioactive material is present in the 

 "aged" sample except ethylene. 



Dr. Teubner: First, I'd like to comment on some work at Michi- 

 gan State on ethylene production in stored apples. I realize Dr. Thi- 

 mann has some objections to working with intact pieces of tissue, but 

 at any rate as horticulturists we must do this. Reviews by Biale (Ann. 

 Rev. Plant Phys. 1: 183. 1950) and by Smock and Neubert (Apples 

 and Apple Products. 486 pp. Interscience, New York. 1950) discuss 

 the delay of the climacteric with high levels of carbon dioxide (5 per 

 cent) and a low level of oxygen. Respiration of the fruit under these 



