Chap. X. 



CONDUCTING TISSUES. 



247 



^V.A 



more central ones. The properly directed movement 

 of the tentacles is not an unique case in the vegetable 

 kingdom, for the tendrils of many plants curve to- 

 wards the side which is touched ; but the case of 

 Drosera is far more interesting, as here the tentacles 

 are not directly excited, but receive an impulse from 

 a distant point; nevertheless, they bend accurately 

 towards this point. 



On the Nature of the Tissues through ivhich the Motor 

 Lrqmlse is Transmitted. — It will be necessary first 

 to describe briefly the 

 course of the main fibro- 

 vascular bundles. These 

 are shown in the accom- 

 panying sketch (fig. 11) 

 of a small leaf. Little 

 vessels from the neigh- 

 bouring bundles enter 

 all the many tentacles 

 with which the surface 

 is studded; but these 

 are not liere represented. 

 The central trunk, which 

 runs up the footstalk, 

 bifurcates near the centre 

 of the leaf, each branch 

 bifurcating again and 

 again according to the 

 size of the leaf. This 



central trunk sends off, low down on each side, a 

 delicate branch, which may be called the sublateral 

 branch. There is also, on each side, a main lateral 

 branch or bundle, which bifurcates in the same 

 manner as the others. Bifurcation does not imply 

 that any single vessel divides, but that a bundle 



Fig. 11. 



(Drosera rotundi/olia.') 



Diagram showing the distribution of the 



vascular tissue in a small leaf. 



