DORMANCY IN BUDS 255 



synthesized glycosides in sufficient amounts to constitute 13 per cent of 

 the dry weight of the leaves. Foreign chemicals can induce plants to change 

 their chemical composition to a marked degree. 



Treating of potato tubers with ethylene chlorhydrin and many other bud 

 forcers, as well as some chemicals that do not force buds, cause an early 

 many-fold increase in respiration. Methyl, ethyl, and isopropyl alcohols 

 decreased respiration but showed some bud-forcing action. Citric acid was 

 used as an important substratum for respiration increase so that a fall in 

 acidity accompanied the great rise in respiration. Treatment of Bryophyl- 

 lum leaves mth ethylene chlorhydrin causes them to oxidize the citric and 

 probably malic acids in darkness, rendering the leaves less acid. Ordinarily 

 light causes the oxidation of these acids. Many of the chemicals cause a 

 much later and marked increase in the sucrose content of the tubers but 

 little change in reducing sugars. Some chemicals that are not effective as 

 bud forcers cause an increase in sucrose. 



Ethylene chlorhydrin in the main did not affect the activity of amylase, 

 catalase, peroxidase, or reducing power of extracted juices of potato tubers. 

 It did induce the formation of more of these enzymes in treated tubers. 

 The thiocyanates and thiourea did not induce an increase in these enzymes 

 that was commensurate with then* bud-forcing action. 



Ethylene chlorhydrin treatment of intact potato tubers increases the 

 permeability of pieces sliced from treated tubers to electrolytes. Thiocya- 

 nates caused a slighter increase in permeability and thiourea induced no 

 increase. The induced increase in permeability was not proportional to the 

 bud-forcing action of the several chemicals. 



Treatment of dormant potato tubers with ethylene chlorhydrin causes a 

 later increase in glutathione amounting to as much as six-fold. Bud-forcing 

 chemicals that contain bivalent sulphur cause much less increase. More- 

 over, the increase in glutathione caused by the several bud-forcing chemi- 

 cals is not proportional to the bud-forcing action. The chemicals seem to 

 induce the synthesis of glutathione rather than cause its accumulation 

 through the hydrolysis of proteins of the tuber, for sulphuric and nitric 

 acids disappear parallel with the increase in glutathione and in approxi- 

 mately the right proportion to account for the sulphur and nitrogen in the 

 glutathione. A fall in acidity accompanies the rise in glutathione. This is 

 accounted for by the use of citric acid in respiration and sulphuric and nitric 

 acids in the synthesis of glutathione. A rise in the reducing power of the 

 juice also accompanies the rise in glutathione. This is accounted for in 

 part, especially in iodine reduction, by the increase in sulphydryl groups 

 in the synthesized glutathione. 



Many chemical changes are caused in plant organs by bud-forcing chemi- 

 cals, as well as by chemicals that are not bud forcers, and there are no doubt 

 many still to be found. The very multiplicity of changes, together with 

 the fact that none of the changes brought about by the several bud-forcing 

 and other chemicals is parallel with the bud-forcing action, means that the 



