154 SCOTCH PINE. 



v. Draw one of the bundles. 



c. Between the bundles and more or less encircling 

 them, especially next the convex side of the leaf, 

 fibrous tissue consisting of large thick-walled cells 

 with small cavities. 



d. On the side of the bundle pair toward the flat 

 side of the leaf, large thin-walled, mostly empty cells. 



e. Filling the remainder of the fibre-vascular region 

 and entirely encircling the parts named, large 

 tracheides resembling the preceding, but with more 

 or less conspicuous contents, and walls marked 

 with bordered pits. Compare the markings with 

 those of the tracheides of the stem, studying both 

 face and section views. 



f. Draw a few cells of each tissue named outside the 

 bundles. 



Cut a longitudinal section through the central part cf the 

 leaf. Examine with a high power, and study 



11. The epidermis. Note 



a. The shape of the cells. Unless the section be quite 

 thin, the epidermis will appear as a continuously 

 thickened border of the section. The end walls of 

 the cells are hard to make out, even in the best 

 sections. 



b. The irregular cavity, and innumerable //& which 

 perforate the thickening layers. 



c. If a number of sections be made, one or more will 

 traverse a line of stomata. Note the shape of 

 the outer chamber, the shape of the guard cells, 

 and of the intercellular space below. 



d. Draw a stoma and the adjacent cells. 



12. Underlying the epidermis, the elongated sclerenchyma 

 cells, the hypoderma. In sections passing through a 



