230 SHEPHERD'S PURSE, 



root grows. Any of the cortical cells may have 

 thickened walls. 



e. The alternating xylem and phloem masses. In com- 

 parison with the sections under A. i. note 



i. The increased number and irregularity of 

 xylem and phloem rows, making longer and 

 shorter radial rows, quite obscuring the 

 primitive arrangement. 



ii. An almost complete disappearance of inter- 

 vening parenchyma, xylem and phloem being 

 in close contact. 



f. Draw a segment showing the tissues noted. 

 Make a radial longitudinal section, and using a high 



power, 



g. Compare thoroughly with the regions of the trans- 

 verse section. 8 



//. Illustrate with drawings. 



B. THE STEM. Make a transverse section, examine with 

 low power, and note 



1. Three regions : 



a. Cortical region. 



b. Fibro-vascular region. 



c. Pith. 



2. IL\& fibrd-vascular bundles ; shape and relative sizes. 

 Examine with a high power, and note 



3. One row of epidermal cells, with very thick outer and 

 inner walls. Note 



a. The cuticle. 



6 Several sections will be needed to show all the regions of the fibro- 

 vascular area. 



