— 259 — 



(Fig. 1 (7), in others, on the contrary, such ones are lacking while 

 there are bundles deeper in the bark; others again are quite with- 

 out bundles in the bark (Fig. 9), or, if as a rare exception bundles 

 are present, they are but very few. 



The endodermis-cells exhibit several differences ; in some species 



(45 : 1). 



Å, 



P. perfoliatus 



Gr, 



P. lucens 



B, 



- color atus 



H, 



- gramineus 



o, 



- natans 



I, 





D, 



- praelongus 



K, 



- crispus 



E, 



- lucens X praelongus 



L, 



- densus 





(— P. decipiens) 



M, 



- zosterifolius 



F, 



- gramineus X perfoliatus 







(= P. nitens) 



The hatched parts = pith ; the white parts = vascular bundles ; the black parts 

 =a mechanical tissue. Ig. channels formed by obliteration of vessels; sg, phloem. 



the cells are thin-walled and, as a rule, with distinct „Gaspary's 

 dots" ; in others the cell-walls are alike throughout and rather 

 strongly thickened : O-Endodermis (fig. 2 D) ; in others, again, the 

 inner-walls and partly the radial-walls are strongly thickened, 

 while, on the contrary, the outer-walls are not thickened or but 



