Fig. 17. Part of a transverse section through the stem of a Spider- 

 wort {Tradescantia Sellei), illustrating the arrangement of the flhro- 

 vasoular hundles in a monocotyledonous stem ; e, epidermis, with a 

 stoma, sp ; B, cortex ; v, thickening ring, with the outer vascular 

 bundles, gi' ;«?", inner vascular bundles. (Magnified.) 



