MANGEL WURZEL OR FIELD BEET 355 



midway between the vascular rings, often has a crimson or yellow 

 tint. In white-fleshed varieties the cell-sap is clear, and these 

 parenchymatous zones are translucent when thin slices are held 

 up to the light. The vascular rings consist of isolated strands 

 or groups of vessels with thin-walled parenchymatous medullary 

 rays between. 



It is outside the scope of the present work to deal with the 

 complex growth in thickness of the root and hypocotyl of the 

 mangel ; but it may be mentioned that each ring of vascular 

 strands, with the medullary rays between and the corresponding 

 zone of thin-walled bast, is the 

 product of a separate cambium 

 tissue. 



The individual cambium-rings 

 arise in the pericyle of the root in 

 rapid regular succession from the 

 centre outwards. 



Sooner or later the cell-division 

 of the inner ones ceases, but the 

 exact length of time during which 

 r 



Fjg. 112. — t. Transverse section of mangel 'root.' 



2. Longitudinal section.^ r Lateral roots ; a ring of vascular bundles ; b thin-walled 

 parenchyma (chiefly bast-tissue). 



each cambium-ring remains active is not certain. In ordinary 

 varieties usually six or seven cambium-rings complete their 



