

IN THE MOTOR ORGANS OF LEAVES. 



93 



the 



occurrence 



f both gradual and 



r 



affecting supply and 

 local filtrative procee 



pid movements under the influence of any factors 



of water generally, or calculated 



give rise to alterations in 



There can be no question that the motor 



tural peculiarities which 



of 



org 



nature specially to favour 



of Mimosa pudica present struc- 



occurrence cf movements 



under the influence of conditions of alterations in 

 fluctuations in assimil atory activity, or on variations in 



escence, whether depend 



local 



pply 



d loss of fluid 



y 



exhibit bears a dir 



d that the eapaeity for rapid 



ditions affect in i 



gen 



( 1 



1IHIV 



which 



text ural faciliti 



whicl 



on 



or 



1 



offer for rapid nltr 

 exceptional provision 



distribut 



ey individually 



In the case of tho primary pulvimi 



» 



v 





for the occurrence of rapid redistribution of fluid is presented by 



the deeper stratum of parenchyma, composed 



f elaborately and 



of extremely open tissue, l»u 



ely pitted 



and in greater part struggl 



f 



resistance, both local and connected with distal 



iff! 



It up 

 treat 



milar fac 



leverago. 



In tho tertiary pulvini, too, 



are present owing to the excessive delicacy and loose texture of the 



superior parenchyma which has to contend with the ove 

 the inferior one and the passive direction of the fibro 



pon 



primary and tertiary pul 



the capacity f 



rapid 



>ring struct 

 cular bundl 

 ement read 



e 



i 



d 



J, fc 



in 



a 



th of 

 both 



ximal 



development. In the secondary pulvini, on the other hand, the nature 

 form character < 



■ly 



rapid redistribut 



f the 

 ion of 



tissue implies an absence of any structural peculiarities favouring 



quid 



in 



such 



ly high degr 



capacity for rapid movements very much less pronounced 



^e, and with this we find 



A study of the motor organs 



Mimosa pudi 



thus 



ds to the same conclusion as that 



ed at from the 



comparative study of the motor organs of nyctitropic 



ca\ 



generally, that rate of 



movement is entirely regulated by structural facilities affecting filtrative escape from the 



the cell cavities of the tissues, whilst amount of movement is dependent on the 



interior of the cell cavities 



extent of possible fluctuations in turg 



in opposing masses of tissue. It alone is 



gh to show how erroneous the idea is that 



in 



the 



opposing masses 



f tissue in 



pul 



we have to deal with differences depending solely on invisible molecular stimture 



d not on the presence of any visible differences in organi 



* 



CHAPTER XI. 



ttLhtortes 



wgarbing Wit movements of the Icabcs of ^limcsa puMca. 



In the preced 



chapt 



attempt has been made to demonstrate that the mov 



ments which are conducted by the 



of M 



pudica are 



tially the same in 



nature and origin as those which are conducted by nyctitropic leaves generally 

 that any peculiarities which they present 



d 



be 



bed 



motor organs permitting of 



ptionally rapid redistribut 



structural features in the 

 of fluid throughout the 



tissues. 



Thi 



view is 



however, entirely opposed to ordinarily accepted belief ; for 



lthough the regular period 



movements are commonly allowed to owe their origin to 



the same causes as those which determine the occurre 



of sim 



movement 



m 



yctitropic leaves, the sudden movements arising under other circumstances 



other 

 those 



• « Es handelt sich also auch hier wieder uichtum sicbtbare Organisation* verbaltnisse, aus denen kich die KeizWkeit 

 erklart, sondem urn die uxmebtbare Molekulstruktur." Sach«, Vorlesung XXX VI, •. 770. 



