MAIZE APEX OF ROOT 183 



III. Cut radial longitudinal sections of the same 

 root : treat in the same way, and observe the several 

 tissues above described. The whole root will be seen 

 to be composed of similar elements to those found in 

 the stem. Note especially that the spirally thickened 

 elements of the xylem (protoxylem) are next to the 

 pericycle. 



In the transverse sections may be found the point of junction 

 of lateral roots with the main root. It may be seen that the 

 former originate from the pericycle of the main root, and 

 that they break through the endodermis, cortical tissue, and 

 piliferous layer ; also that their vascular tissue is continuous 

 with that of the main root : the activity which produces them 

 begins opposite a phloem-mass of the main root, and not 

 opposite a xylern-mass, as is usually the case. This is to be 

 connected with the fact that the xylem groups in the Maize (and in 

 most Grasses) abut directly on the endodermis. 



Apex of the Eoot. 



It is not easy to cut longitudinal sections of the apex 

 of an ordinary fully developed root without embedding 

 The arrangement of the meristematic tissues is, how- 

 ever, the same in young as in old roots ; it is therefore 

 more convenient, and quite as successful, to cut longi- 

 tudinal sections of the apex of the young lateral roots, 

 which are to be found growing horizontally out of the 

 nodes of the Maize plant. Or, if fitting material for 

 this be not at hand, longitudinal sections may be made 

 of the radicle of the embryo. 



Adopting one of the above methods, cut longitudinal 

 median sections of the apex of the root. The section 



