CHAPTEE XY. 

 THE INTERNAL STRUCTURES OF PLANTS. 



EXERCISE LXII. 

 Cells and Cellular Tissue. 



ORDINARY plants differ so little in their inner 

 structure, that almost any specimen will furnish you 

 with examples of cells and tissues ; but these ele- 

 ments are more conspicuous in some parts of plants 

 than in others. For instance, make a thin cross-sec- 

 tion of the pith of elder, or, if you cannot get this, 

 of the pith of any young twig. A sharp, thin-bladed 

 knife, and some practice, are needed to make the 

 slice so thin that it will distinctly show the structure. 

 Put the slice upon the slip of glass provided for the 

 purpose, and add to it a drop of water. Place over 



FIG. 356. 



it a thin glass cover, which must first be permitted 

 to rest on one edge, and then be slipped down care- 

 fully to push out air-bubbles. Under the microscope 

 the slice presents an appearance like Fig. 356. 



