DORMANCY IN BUDS 249 



tinuously, so that after 144 hours it is about 125 per cent above the control 

 and after a longer period it equals the control. 



The decrease in citric acid and H-ion concentration ^^ starts at the same 

 time as the increase in respiration, and they reach their mmimum at about 

 the same time that respiration reaches its maximum. Citric acid is no 

 doubt one of the substrata for respiration and its oxidation reduces the 

 H-ion concentration. 



The H-ion concentration is still further reduced by the consumption of 

 both the sulphate and nitrate radicals,^^ probably in the synthesis of the 

 tripeptide, glutathione. The content of these radicals begins to fall when 

 the rise in glutathione begins and continues with the rise in glutathione, 

 as would be expected if they were used up in the synthesis of the latter. 



The two enzymes, catalase and peroxidase, begin to rise some hours after 

 the start of the respiration rise, and continue to do so for many hours after 

 respiration has reached its maximum. Catalase reaches its maximum before 

 the 144th hour, while peroxidase is still rising at this hour. The increase in 

 content of these two enzymes does not hold a causative relation to respira- 

 tion rise. 



The rise in sucrose content starts still later and continues at a nearly 

 uniform rate to the end of the determinations. It is quite apparent that 

 the respiration rate is independent of concentration of sucrose present as 

 a substrate for oxidation, and that no positive causal relation exists between 

 respiration intensity and sucrose content. Of course with rise in sucrose 

 content there is a fall in starch content, but the percentage fall in the latter 

 is rather small because starch constitutes a large percentage of the weight 

 of the tuber. 



The rise in glutathione content was the latest of the changes recorded in 

 the curve. This rise started at the 48th hour and continued a little beyond 

 the 96th hour, after which it remained constant at nearly 200 per cent 

 above the check. 



Metabolic Changes Induced by Ethylene Chlorhydrin Compared 

 With Effects of Other Chemicals Including Other Bud Forcers 



Respiration. It might be thought that the great increase induced by these 

 chemicals in the fundamental process of respiration explains their bud- 

 forcing action, but such seems not to be the case, as further facts show. 

 Treatment of potato tubers ^^- ^^ with many other chemicals (ethylene 

 bromide, hydrogen sulphide, acetaldehyde, hydrocyanic and hydrochloric 

 acids, ethyl mercaptan, alkyl, alkylene, and alkylidene halides, etc.) shows 

 practically the same respiration curves as does ethylene chlorhydrin. 

 Hydrocyanic acid has only moderate bud-forcing action, and hydrochloric 

 acid less. Methyl, ethyl, and isopropyl alcohols,^'' which have moderate 

 bud-forcing action, decrease respiration of the tubers. When intact potato 

 tubers are treated with vapors of both ethyl alcohol and ethylene chlorhy- 



