290 PKACTICAL BOTANY 



d. Round the latter are a number of isolated, large 

 vascular bundles, forming an interrupted ring. 



e. Outside these, and running out into the leaves, 

 are numerous smaller bundles of the leaf-trace, 

 which appear to be less regularly arranged. 



III. Divide the stock, including the apical bud, into 

 two symmetrical halves by cutting it in a median longi- 

 tudinal plane : smooth one of the cut surfaces with a 

 razor, and observe 



a. That the stem is of almost equal thickness through- 

 out its length, i.e. it is roughly cylindrical. 



1}. That its external conformation is very irregular 

 by reason of the closely crowded insertion of the 

 leaves. 



c. The bulky central pith as before. 



d. The large vascular bundles (d above), which are 

 not continuous in direct longitudinal lines, but form an 

 interrupted series. 



e. The smaller bundles of the leaf-trace (e above), 

 which in some cases may be followed, after a little 

 careful dissection of the parenchyma which surrounds 

 them, from one of the larger bundles of the central 

 system into the base of one of the leaves. 



Slice away carefully the external tissues of the 

 posterior part of the stock, so as to lay bare the central 

 system of larger bundles : it will then be seen that these 

 form a continuous network with large meshes, and 

 that each mesh is opposite the point of insertion of one 

 of the leaves, hence it is called a foliar gap. Observe 

 also that the vascular bundles, which pass out into any 

 individual leaf, are given off from the margin of its 

 own mesh. 



