viii.] BOTANY. 37 



bundles of nbro-vascular tissue (Pan 9), not arranged 

 in a ring, or in concentric rings, but scattered without 

 order through the cellular tissue, and much crowded 

 at the circumference of the stem. Each of these 

 isolated bundles consists outwardly of bast-cells and 



FIG. 19. Transverse section of stem of a Monocotyledon. 



inwardly of wood-cells, exactly as in the first year's 

 stem of flax or lime (Par. 54). These bundles do 

 not, however, increase by the addition of bast-cells 

 and wood-cells. 



60. Commencing at the bases of the leaves, all the 

 fibro-vascular bundles of a Monocotyledon may be 

 traced downwards, first arching inwards towards the 

 centre of the stem, then gradually outwards to its cir- 

 cumference, where they are closely crowded. There 

 is hence no true bark, though sometimes the cellular 

 tissue surrounding the vascular bundles forms a separ- 

 able outer layer, as in the dragon-tree (Dracaena), in 

 which also new bundles are formed which are disposed 

 in concentric rings as in Dicotyledons (Par. 56). In 

 all cases, however, the individual bundles are not 

 added to as in Dicotyledons, and they are hence called 

 definite bundles. 



