THE PIBKO VASCULAR SYSTEM. 



113 



142. In the fibro-vascular bundle of the stem of Indian 

 corn (Zea mais) the central portion is composed of tracheary 



Fig. 102. Transverse section of fibro-vascular bundle of Indian corn (Zea mais). 

 a, side of bundle looking toward the circumference of thoftem; i, side of bundlelook- 

 ing toward the centre of the stem ; p, thin-walled parenchyma of the fundamental 

 tissues of the stem; ff, g, large pitted vessels; , spiral vessel; r, rin^ot an annular 

 vessel ; I, air-cavity formed oy the breaking apart of the surrounding cells; v, v, 

 latticed cells, or soft bast, a form of sieve tissue. X 550. After Sachs. 



tissue, consisting" of pitted, spiral, ringed, and reticulated 

 vessels (Fig. 102, #, g, 8, r, and the tissue between v s,g g) 



other hand, considers the cylindrical portion in the centre as but one 

 bundle, belonging to what he terms the Radial type. Both agree in con- 

 sidering the fibrous tissue outside of the bundle sheath as not belong- 

 ing to the bundles ; but certainly if this is one bundle, there is as good 

 reason for including the fibrous cylinder in it as there is in the case of 

 thf bundle of Indian corn. 



