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BOTANICAL GAZETTE 



Johannsen's experiments. Jesenko (12) found that hydrochloric, 

 sulphuric, and tartaric acids, as well as alcohol and water saturated 

 with carbon dioxide, hastened the germination of buds of a number 

 of woody plants. He concluded that the applied solutions not only 

 acted as a stimulus in the strict sense of the word, but also started 

 certain chemical processes in the buds which produced favorable 

 conditions for growth. Jost (13) observed that wounded potatoes, 

 especially if they were cut into many pieces, showed an earlier ger- 

 mination of the buds than unwounded ones. 



Wismewski (31) experimented with the winter buds of certain 

 aquatic plants. The rest period of the buds of Hydrocharis Morsus- 

 ranae could be shortened by wounding and lengthened by darkness. 

 Hydrocharis formed buds the entire winter when kept in darkness 

 and immersed in rainwater or a nutritive solution. He concludes 

 that neither the origin nor germination of these buds is con- 

 ditioned by an inner rhythm of the plants. He also states that 

 low temperature is not a necessary condition for the origin of 

 buds. 



Although the rest period may be shortened by artificial treat- 

 ments, none has thus far been capable of entirely eliminating the 

 rest period where it is well fixed. A great deal of work has been 

 done on forcing resting stem structures into growth by artificial 

 means, but comparatively little has been done to determine the 

 character of the physiological and chemical changes effected by 

 such treatments. Still less is known about these changes during 

 the natural rest period. 



Muller-Thurgau and Schneider-Orelli (21, 22) found 

 increased respiration in potato tubers and lily-of-the-valley bulbs 

 after the warm-bath treatment and also after etherizing. 



Iraklionow (27) also found a rise in respiration of potato tubers 

 after treatment with warm water. At the end of a few days, how- 

 ever, it fell back to the normal rate and did not rise again until the 

 beginning of germination. He assumes, in agreement with 

 Molisch, that the breaking of the rest period by means of the warm 

 bath is a simultaneous action of the high temperature and the 

 water, and that the warm bath influences the enzymes, chiefly the 

 oxidases. 



