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1 92°] CHILD & BELLAMY— BRYOPHY LLUM 259 



usually clearly visible before its removal, and growth always con- 

 tinued afterward in at least a considerable number of notches. 

 When the coil remained on the petiole for ten days or more, death 

 of some of the epidermal cells usually occurred, although internally 

 the petiole might be completely intact and to all appearances in 

 good condition. Probably such superficial injuries were without 

 effect, but cases in which they occurred were not regarded as 

 conclusive. 



Bryophyll 



periments 



In fifteen 



of these there was some injury to the petiole, but in the other 

 thirteen no injury was apparent. In all these experiments not 

 only the experimental leaf, but the opposite leaf, and usually one 

 or more leaves of nodes above and below the node of the experi- 

 mental leaf, were more or less completely submerged, in order to 

 determine to what extent these leaves were also affected. Usually 

 all, or nearly all, buds on the submerged portion of the experi- 

 mental leaf and in most cases those of the leaf opposite developed. 

 On some leaves individual buds had been killed or injured by 

 plant lice, from which the plant could not be kept entirely free. 

 As far as possible, leaves were selected for experiment on which 

 all the buds were apparently intact, but occasionally such buds 

 failed to grow. 



In order to determine whether cooling of a zone of the petiole 

 stopped the flow of water to the leaf, experiments were performed 

 in which the experimental leaf remained in air of medium humidity, 

 instead of being submerged. Such leaves did not wilt, but remained 

 fresh and in good condition, w r hile leaves separated from the plant 

 and exposed to the same atmosphere showed distinct wilting in 

 the course of a few days. Evidently the cooled zone does not 

 appreciably affect the flow of fluids to the leaf. The following 

 descriptions and figures of typical experiments will serve to show 

 the results attained. 



Series 35, March 12, 1919. — Temperature of 2.5-3° C was 

 placed on petiole of one leaf of the eighth pair below the tip. The 

 terminal leaflet of this leaf, of the opposite leaf, and one leaf of 

 the ninth pair were submerged. Growth was visible in both leaves 



