PIN US S YL VESTRIS. 1 5 5 



line of stomata, note the absence of any hypoderma, 

 except short cells between the guard cells of adjacent 

 stomata. 



13. Draw a few cells of epidermis and hypoderma. 



14. The mesophyll. Note how loosely it is arranged, with 

 an intercellular space between the rows of cells, enlarg- 

 ing under each stoma. Note also the shapes of the 

 cells, the apparent absence of infoldings in this view, 

 and the number of cells in each row between the bun- 

 dle sheath and hypoderma. The determination of the 

 latter point will need close inspection and careful 

 focusing. The infoldings seen in transverse section 

 are now seen as apparent partitions increasing the 

 apparent number of cells above the actual. In places 

 none of these false partitions occur, and the real number 

 of cells may be easily noted. Draw a few rows of meso- 

 phyll cells. 



15. The resin ducts ; note the sheath cells, elongated and 

 thick walled ; the secreting cells, with thin wavy walls 

 and prominent nuclei. Draw. 



1 6. The fibro-vascular region. The various tissues of this 

 region appear as strips in this section. 



a. The bundle sheath ; a row of elongated cells next 

 the mesophyll. Draw. 



If. The tracheides, on both sides of the bundles ; 

 note the shape and markings of the cells. 



c. Note the change in shape where this tissue adjoins 

 the fibrous tissue, the cells becoming much elon- 

 gated. Draw, showing both forms. 



J. The fibrous tissue ; greatly elongated thick-walled 

 fibers with tapering ends, next the tracheides. 

 Draw. 



