MICROSCOPIC OBJECTS. 37 



Fig. 73. Transverse Section of the Stem of Sarsaparilla 

 (Smilax Sarsaparilla), x 40. Endogen. 



The drawing illustrates another endogenous stem, as seen 

 in the common Sarsaparilla of commerce. The clusters of 

 large holes represent the bundles of vascular tissue, and the 

 network the parenchymatous or cellular tissue. The Sarsa- 

 parilla plant belongs to the N. O. Smilacese a small Natural 

 Order, but one containing some valuable plants. 



Fig. 74. Transverse Section of Pilea smilacifolia, x 40. 

 Exogen. 



This section of the pith of one of the exogenous plants of 

 the Natural Order Urticacese has been taken to show the 

 transformation of many of the parenchymatous cells, by a 

 process of secondary deposit, into thickened cells having a 

 tendency to form wood, woody fibre, or prosenchymatous 

 cells, as will be seen in observing this and other herbaceous 

 plants. 



