ROOTS 45 



than in the older and larger portions of the root. Sketch one section 

 of each kind. 



Examine with a higher power (100 to 200 diameters), and note the 

 ends of the thick-walled wood-cells. Compare these with Fig. 72. 



Notice the many thinner-walled cells composing stripes radiating 

 away from the center of the root. These bands are the medullary 

 rays, whose mode of origin is shown in Fig. 68. Moisten some of 

 the sections with iodine solution, 1 and note where the blue color 

 shows the presence of starch. Split some portions of the root through 

 the middle, cut thin sections from the split surface, and examine with 

 the high power some unstained and some stained with iodine. 



Notice the appearance of the wood-cells and the ducts as seen in 

 these sections, and compare with Fig. 58. 2 



56, Structure and Contents of a Fleshy Root. In some 

 fleshy roots, such as the beet, the morphology of the parts 

 is rather puzzling, since they form man}*- layers of tissue 

 in a single season, showing on the cross-section of the root 

 a series of layers which look a little like the annual rings 

 of trees. 



The structure of the turnip, radish, carrot, and parsnip 

 is simpler. 



Cut a parsnip across a good deal below the middle, and stand the 

 cut end in eosin solution for tw T enty-four hours. 



Then examine by slicing off successive portions from the upper 

 end. Sketch some of the sections thus made. Cut one parsnip 

 lengthwise and sketch the section obtained. In what portion of the 

 root did the colored liquid rise most readily ? The ring of red marks 

 the boundary between the cortical portion and the central cylinder. 

 To which does the main bulk of the parsnip belong? Cut thin 

 transverse sections from an ink-stained parsnip and notice how the 

 medullary rays run out into the cortical portion, and in those sections 



1 If the roots are in their winter condition. 



2 The examination of the minute structure of the root is purposely made 

 very hasty, since the detailed study of the structural elements can be made to 

 better advantage in the stem. 



