440 



BOTANY. 



pair of leaves. 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 



passes downward 

 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> 1) } r > u > P a ' c ' s 



down through two 

 internodes, a n d 

 then fork right 

 and left, a n d 

 unite with other 

 descending bun- 

 dles. Thus in 

 any intornode 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 A,/, (/, k, i pass 



Fig. 815. Diagram showing the arrangement < 

 flbro-vaecular bundles in the stem of Lathi/rw< Ptoeuda- 

 phaea. The bundle* nearest, the obi-crv. r are figured dark- 

 er, those farthest away lighter. -After Nageli. 



