THE SEEDLING AND YOUNG PLANT 43 



Now, the important point to apprehend first is that 

 these strands at the corners (M, s) are the strands which 

 pass directly into the leaves through the petioles, and 

 it is necessary to be perfectly clear on this subject in 

 orde'r to understand much of what follows. For instance, 

 the three strands marked M in fig. 9, A (mm, ms, and 

 ms in fig. 10), pass directly into a given leaf, mm, in 

 the middle, flanked by ms on either side; but this 

 group is also accompanied on each side by another strand, 

 (marked s, s' in fig. 9, A, and Z, I in fig. 10), so that five 

 strands may be regarded as contributing to each corner 

 of the section, the three middle ones running side by 

 side up the midrib of the leaf and then branching out 

 in a manner to be described subsequently. 



It can be shown, moreover, that the larger curved 

 strands, occupying the sides of the pentagon, are simply 

 formed by the union of several of the smaller strands at 

 different levels. 



If, now, successively lower sections are cut of the 

 very young shoot, and compared, or if the shoot is 

 softened and dissected, it is possible to make out the 

 course of these vascular bundle strands lower down ; 

 the course is somewhat complex, but the diagrammatic 

 sketches in fig. 11 will enable the reader to apprehend 

 the chief points. 



In the first place, the middle strand from a leaf, 

 mm, passes vertically down in the angle of the young 

 stem through five internodes (marked by the horizontal 

 lines), turning to one side and becoming continuous in 



