118 



THE CAUSES OF FLUCTUATIONS IN TUMESCENCE 



■ 



but by a discharge of liquid from the cut 



face 



In most 



y 



und 



\ 



conspicuous; and, 



can readily be determined that 



at an appreciable interval after 



if the tip of a pinnule be gently amputated 



humidity is excessive, 



which movements do not 



$ the discharge is ve 

 occur very rapidly, it 

 movements only ensue 



- 



has begun to manifest itself. For example, 



at a time when telluric and atmospheric 



and if all contact disturbance of the tertiary pulvinus have been 



the primary result, and 



ccessfully avoided, no 



ovement wl 



occurs for a considerable interval. 



But 



of liquid appearin 



dr opl et 

 divided extremity of the midrib, and smaller drops presenting 



during this interval conspicuous exudation occurs on the cut surface, a prominent 



themselves near the margins of the lamina over the cut end 



s 



exudation of this nature is present, we have to deal 



local redistribution of 



quid 



hout the 



but an 



of veins. But wherever 

 conditions which imply 



active discharge and 



of a portion of the general stock of liquid available for the up-keep of turg 



and hence a disturbance in the pre 



quilibrium between 



pply 



d loss. 



This 



disturbance 

 the actual 



ly be liable to extend 



greater or less degree according to 



of loss which takes 



and to the conditions of the tissues, of the 



soil, 



d of the 



at 



time 



which it occurs. Tl 



expect that 

 by phenoin 



therefore, good ground to 



+ 



>wed 



i "stimulation" should be more frequently and more extensively follow< 

 of diffusion of movement beyond the site of primary origination than is 



stimulation" by agencies givm 



Even 



most casual observ 



is 



mere alterations in local pi 

 lply sufficient to 



show that 



B and filtration, 

 this theoretical 



demand is fully met by actual fact. Whilst isolated pinnular movements are 



j 



average condit 

 isolate! move: 



of 



idity, the normal sequence 



of 



stimulation 



under 



purely 



quite 



iptional phenomena, only occurring in association with 



ditions of excessive humidity, after incision of the tissues. Where 



atmospheric and telluric humidity are, and have for some 



been 



putation of the tip of a 

 ured pinnule on 



lam 



or, m 



the 

 under 



primary pulvinus alone; b 



contact is followed by strictly localised movem 



amputation or incision 



conditions of 



cessively high, 

 is occasionally followed by movement in the 

 case of heavily-laden leaves, by action in it and the 



rage humidity, and at times when 

 in the primarily affected pinnule, 



ditions of 



of the tip of a pinnule is followed by movements 



extending 



along the entire course 



of 



that secondary rachis, at least 



Whei 



:e 



cond 



of 



humidity are higher, the propagation of movement becomes more limited and extends only 

 partially over the course of the rachises ; and, on the 

 that contact is liable to be followed by diffusion 



hand, when conditions 



sucl 



of movement, incision or amputat 



attended by movements which are often propagated throughout the entire area of the 



leaf 



W hen 



stimulation" is attended by strictly localised movement, incision 



amputation is ordinarily followed by movement 



g 



portion of the leaf 



and 



attended by a limited amount of diffusion of movement 



or 



putation is ordinarily followed by movements extending throughout the entire leaf 



possible explanations of these differences 



The or 



stimulant to protoplasmic 



th 



mor 



effi 



determinant of 



strong 



pre-existant relations between supply and loss of liquid than contact is. According to the 

 ordinarily accepted theory we must assume that it is the former without, however having 



any independent evidence that it actually 

 of movement we are not obliged to make 



ding 



the purely physical theory 



are 



such 



leav 



any groundless assumption, as 



no room for doubt that it actually does give rise to 



phenomeu 



» 







i 













