52 BOTANY. 



sheath (s); the latter is bounded interiorly by a layer of 

 actiTB thin-walled cells (the pericambium), from which new 

 roots originate. In the older roots the central cell-mass is 

 transformed into stony tissue. 



88. The bundle of the larger Club-mosses (Lycopodinm) 

 contains several parallel plates of tracheary tissue (Fig. 34). 

 Between the tracheary plates there is in each case a row of 

 sieye-tubes imbedded in a lignified tissue composed of 

 elongated cells (stony or fibrous tissue ?). Around this 



Fio. 84.— Magnified cross-section of the stem of a larger Clul3-moss (Lyco- 

 podium complanatum), showing a flljro-vascular bundle. 



central fibro-vascular portion there is a layer of soft tissue 

 (parenchyma), and outside of this a bundle-sheath, exterior 

 to which lies a thick mass of fibrous tissue completfely 

 enveloping all the previously described tissues. 



89. The bundle in the smaller Club-mosses (Selaginella) 

 is much like a single plate of the preceding. There is in 

 each bundle a central plate of tracheary tissue, consisting 

 of a few narrow spiral vessels in its two~ edges and a' re- 

 maining mass of scalariform vessels (Fig. 35). The tra- 



