THE FIBRO-VASOULAR SYSTEM. 



117 



146. — The bundle of the adventitious root of Ranunculus 

 repens is very different from the one just described. It may 

 be briefly described as composed of a mass of tracheary tis- 



Pig. 106.— Transverse section of hypocotyledonary portion of etem of Blcinut com- 

 munis, r, r, parenchyma of the primary cortex ; m, parenchyma of the pith ; d, 

 bast fibres ; y, y, soft bast ; c, cambium ; g, g, large pitted vesei'Is ; t, t, smaller pit- 

 ted vessels ; cb, continuation of the cambium into the parnnchjraa lying between the 

 bundles — the parenchyma cells are repeatedly divided by tangential walla. Between 

 the primary cortex r and the fibrous tissue of the phloem lies a layer, the so-called 

 bundle-sheath, filled with compound starch grains. Highly magnified.— After Sachs. 



sue, which is cross-shaped, as seen in transverse section (ff, 

 r, g. Fig. 108), 'and four masses of sieve tissue, -which lie in 

 the angles between the projecting portions of the tracheary 

 tissue. Around the whole is a layer of pericambium (p, 



