12 BOTANICAL GAZETTE [july 



on the abaxial side. The sheaths of the two bundles between 

 which the leaf trace enters soon open, the ends becoming con- 

 nected so as to form a complete sheath around the two bundles and 

 the leaf trace (fig. 4). The inner face of the sheath now bulges 

 toward the central bundle, finally coming in contact with it, and 

 breaking at the point of contact, thus forming a continuous sheath 

 inclosing a dumb-bell-shaped area, each head consisting of the leaf 

 traces and the two side bundles of the stem, the central bundle in 

 the middle of the connection. The endodermis on each side of 

 each "head" now bulges toward the remaining pair of stem bundles, 

 coming in contact with the endodermal sheaths of the latter, and 

 breaking at the point of contact. 



There are thus formed three complete rings of endodermis (fig. 

 5), one externally surrounding the vascular ring, the other two 

 internal, one on each side of the transverse connecting arms. 

 These connecting arms very soon break, the endodermis sinking 

 in so as to form one sheath around the central bundle, and another 

 lying just internal to the vascular ring (fig. 6) . This vascular ring 

 now breaks into four parts, the endodermis sinking in until the 

 external and the internal sheaths meet, then breaking apart, thus 

 forming the four bundles of the lower internode, each surrounded 

 by a complete endodermal sheath (fig. 9). 



Late stage of seedling 



As has been said, the seedling, by the end of the growing season, 

 attains a height of about 2 dm. Such a plant (fig. 31), possessing 

 about 20 nodes, looks very much like a plant of the "mature" 

 type, but is smaller than the mature plant, and of course differs 

 in not having arisen from a rhizome. At the base, several of the 

 axillary buds have developed to form short, nearly horizontal 

 branches, the rhizomes. At the very base there is a cluster of 

 four strongly developed adventitious roots, nearly surrounding 

 the primary root, which is still less developed than the adventitious 

 roots. 



A histological examination shows that the vascular system has 

 developed in the manner already described. The uppermost pair 

 of leaves furnish a single trace each: these Dass downward to the 



