DORMANCY IN BUDS 251 



the last two. None of the chemicals increased the enzjTne activity of the 

 extracted juice of untreated tubers, so their effect was in inducing the tubers 

 to form more enzymes or more active enzymes. While the thiocyanate 

 increased the formation of catalase, it inhibited its activity in the extracted 

 juice until the chemical was partially dialyzed out. The enzyme changes 

 were greater in the tissue nearer the eyes than in that more distant from 

 the eyes, but the treatment of tubers with eyes removed gave some increase 

 in the enzymes. While there was a general correlation between increased 

 enzyme activity and the sprouting response, this correlation was not very 

 close. Sodium thiocyanate and thiourea were much less effective in increas- 

 ing enzyme acti\aty than would be expected on the basis of the favorable 

 sprouting response. Ethylene chlorhydrin treatment gave much greater 

 increase in the enzyme activity in whole tubers than in cut tubers, although 

 it forced sprouting much better in the latter. 



Sugars. Potato tubers treated ^A-ith ethylene chlorhydrin, thiocyanates, 

 or thiourea ^^ showed marked increases in sucrose but no significant changes 

 in reducing sugar. IVIany of the other chemicals ^^' ^^ that brought about a 

 great increase in respiration of potato tubers also caused marked increases 

 in sucrose, but the latter followed the respiration increase by many hours. 

 In many cases the sucrose of the treated tuber was lower than that of the 

 check when the respiration was at maximum. It is evident that the rise in 

 sucrose does not account for the breaking of the dormancy, for ethyl alcohol, 

 which is a fair breaker of dormancy, causes a fall in respiration and httle 

 change in sucrose; and acetone, which does not break the dormancy, causes 

 a considerable rise in sucrose. 



Permeability. Freshly harvested tubers or seed pieces of tubers ^^ were 

 treated with the most effective sprout-inducing dosages of ethylene chlor- 

 hydrin, potassium thiocyanate, and thiourea, and the electrical conduc- 

 tivity of the tissue and the leaching of electrolytes from the tissue were 

 later measured. Ethylene chlorhydrin treatment produced small but 

 significant increases in the conductivity of the tissue and in the leaching of 

 electrolytes from the tissues when placed in water. Potassium thiocyanate 

 treatments produced changes somewhat smaller, but similar to those pro- 

 duced by ethylene chlorhydrin, while no significant change was produced 

 by thiourea threatment. Here again the change in permeability induced 

 by the three bud-forcing chemicals is not in proportion to their sprouting 

 effects and does not furnish an adequate explanation for bud forcing. 



Synthesis of glutathione and related changes. Ethylene chlorhydrin 

 treatment *'" of potato tubers increases the glutathione content of the tubers 

 as much as six-fold. There are two possible sources of the increased 

 glutathione: induced hydrolysis of proteins in the tuber, and induced 

 synthesis of the physiologically significant tripeptide. Guthrie ^^' '^^ thinks 

 the second is the method of origin, for sulphuric and nitric acids decrease 

 in the tubers parallel with glutathione increase. The two acids furnish the 

 sulphur and nitrogen respectively necessary for the synthesis. Since more 



