

THE CAMBIUM Z< >NE 



from the cambium. While the vascular bundles are verj small 

 it will be noticed that the parenchyma cells separating the vascu- 

 lar bundles begin to divide so as to form a line of cells connecting 

 the cambium of each bundle (Fig. 52). In some cases these 

 divisions are at firsl somewhal irregular but soon the growth 

 results in the formation of cells with parallel walls and in this 

 way a ring of regular cells, the cambium zone, i> formed which 

 continues t<> divide as already noted in the cambium of the 



bundles (Fig. 53). Consequently new cells are now added not 

 alone to the vascular bundles but also along the entire extent 



Fig 54 1 ''"it "i item "' castor bean three weeks older than 



one Bhown in Fig. 53. Note the changes thai have occurred in the stem 

 and especially the numerous cells thai have been added t" the xylem. 

 rk; /•//. phloem; cam, cambium zone. II. 0. Hanson 



of the cambium /one. This growth results in the formation 

 of a layer of xylem on the inside of the cambium zone and a 



layer Of phloem on tin- OUtside, and so brings about the principal 



enlargement of die stem (Fig. 54). This growth is rep 



