142 CUNNINGHAM ON FLUCTUATIONS IN TUEGESCENCE. 



thorough application of the points of heated forceps to points in the course of mature axes was followed 

 in every case by an entire absence of any movements in any leaves either in the centripetal or the 

 centrifugal direction. This experiment clearly proves that no mere fluctuations in pressure in the liquid 

 ©ontaiml in llaberlandt's " Reizleitende system" are efficient to occasion any propagation of move- 

 ments. The local application of heat must here, as usual, have given rise to an elevation of pressure 

 within the liquid contained in the Bystem of sieve-tubes, and as usual this elevation must have 

 been propagated in both directions, and yet no movements whatever took place either centripetally or 

 centnfugally. The absence of the ocourrence of any centr i f ugally propagated movements under such 

 circumstances is readily explicable if we regard the centrifugal propagation which is ordinarily present as 

 the ult of obstruction t-> the ascent of water along the water-conducting system incident on the 

 great gaseous expansion oa ed by the local application of heat. Under the circumstances prevailing at 

 the time of th* experiment not only must the entire water-conducting system have contained an excess 

 of water, but transpiratory loss of water must have been practically absent. But this being so, there 

 1$ no reason why a temporary obstruction or arrest in the passage of water along the water-conducting 

 system should have given rise to the occurrence of any centrifugal propagation of movement; for with 

 minimal transpiratory loss and the presence of large quantities of reserve-water within the water-conduct- 

 ing system, there was no immediate demand for continuous root-supply in order fully to meet the 

 demands of the motor organs, and the temporary obstructive effect of the gaseous expansion might well 

 have entirely disappeared ere such a demand arose. 



•kkimext XXVIII.-July 24th, 8 a.m. Atmospheric temperature 78-5°^. Humidity 94 per cent 

 The morning was cloudy. Very heavy rainfall had occurred shortly before the period of experiment and every, 

 thing was drenched tcith moMure.-Seanng points in the course of mature axes was followed only by 

 slow imperfeot action in the first leaf beyon.i the injured point. 



o 



CROUP B. 



LOW 



a.-Resulls following amputation of terminal pinnules of distal V innce, or amputation 



1. 



tips of axes. 

 Effects following the amputation of tips of pinnules. 



ExPER 



Lxperiment XXIX.— Complete elevation of all the pinnules of nil tl,. • 

 of the primary petiole of the injured leaf. ° pmMB and dee ? depression 



Experiment XXX.— Complete 



EXPERIMENT XXXI 



the 



ijured leaf and depression of 



Experiment XXXII 



Experiment XXXIII. 

 Experiment XXXIV 



n throughout thp nlm, 



the 



the 



™.K~- .uuon throughout the whole of the injured leaf 

 Complete action throughout the whole of fh* ■ • > 7\ 

 of the leaf next aboveit on the ax "^ Ms *""* """^ 



Experiment XXXV.-Complete action in the injured Uf fltl d ■ si 



axis. mjUred kaf and "» the one next above it on 



Experiment XXXVI.-Complete action in the injured leaf Ml a t. 



below and fh« , no „«-* .u„__ ... ., . iU i mea l <*t, followed by comrdpfA *^; nn ,« ^ 



Experiment XXXVII.-Complete action in the 

 one next below and the one next above it on the axis 



ExrERlMF.NT XXXVI] 



Experiment XXXIX 



jured leaf, followed 



com 



whole 



e injured leaf. 



Experiment XL.-Complete action throu^hou th \, ° f tbfl ^^ leaf * 



Brst leaf above it on Z axis; 2^7 £ £» ° f £ «*«* Ml complete action in 



ules of the third leaf above the injured one P **" P6tl ° Ie aud P^ial elevation of the 





