440 



BOTANY. 



pair of leares. The bundles from the third internode pass 

 downward, and in like manner join those from the second 

 pair of leaves, and so on. Thus in such a stem every bundle 



downward 



Mg. 315.— Diagram showing tbe arrangement of 

 flbro-vascular bundles in tlie stem of Lathyrus Pseuda 

 phaca. The hnndles nearest the observiT are figured dark- 

 er, those farthest away lighter. —After Nageli. 



through one in- 

 ternode before 

 joining another, 

 and in any inter- 

 node all the bun- 

 dles are derived 

 from the leaves at 

 its summit. 



In Fig. 315, 

 with a similar ar- 

 rangement in the 

 main, there are 

 some complica- 

 tions. The lateral 

 leaf-bundles {b, c 

 in the lower inter- 

 node, and g, h in 

 the next one) pass 

 downward to the 

 next node, where 

 they unite with 

 other descending 

 bundles ; and the 

 median bundles, 

 a,f, I, 0, r, u, pass 

 down through two 

 internodes, and 

 then fork 

 and left, 

 unite with 

 descending 



right 

 and 

 other 

 bun- 



dles. Thus m 

 any internode there are bundles from at least three leaves. 

 This is shown in the cross-section of the next to the lower 

 internode (Fig. 316), in which the bundles Ji, f, g, h, i pass 



