362 
FREDERICK J. PRITCHARD 
seem to depend upon the structural relationship of its different parts. 
The tissues of the root as shown in cross-section (fig. i) show a con- 
centric appearance resembling the annual rings of a tree. Wood- 
zones alternate with zones of parenchyma.^ The former^ are richer 
Fig. I . Cross-sections of sugar beet roots showing wood-zones and parenchyma- 
zones. (Photograph by Harry B. Shaw.) Sections 2, 4, and 5 are cut from the 
root; sections i and 3 from the lower part of the crown. 
in sugar than the latter, hence the greater the number of wood-zones 
and the closer they lie together, the richer the root. 
The percentage of sugar in the beet depends somewhat upon the 
size of the root. As small roots usually have as many zones of wood 
as large roots and relatively less parenchyma, they contain the higher 
average percentage of sugar. The relationship between percentage of 
^ Bundles from adjacent wood-zones frequently anastomose, but the zones are 
fairly distinct in cross-section, except in the crown, where they run obliquely. 
2 Samples of 30 roots separated into wood-zones and parenchyma-zones and 
analyzed separately showed an average difference of 2.6 percent sugar in favor of the 
wood-zones. This is due to the greater abundance of sugar in the sieve cells and 
proserichyma immediately surrounding the bundles. 
