﻿of the Emhryo of Indian Corn 313 



era! rows of cells. The wide-lumened vessels toward the center 

 are not in direct line with the outer xylem elements and stand 

 quite isolated. They have somewhat thickened fibrous elements 

 however, immediately around them. The medulla is made up of 

 ordinary conjunctive tisssue. 



The Stem. The bundles of the stem of corn present the well- 

 known collateral type with the characteristic vessels, figures of 

 which are given in most of the botanical text-books. 



Transition of Bundles in passing from Root to Stem. The 

 change from the collateral bundles of the stem to the radial bund- 

 les of the root, presents in this plant an interesting peculiarity. In 

 tracing the course of the bundles from the root back to the stem 

 it at once becomes apparent* that the radial type of bundle is main- 

 tained in the internode above the scutellum (fig. 3). The structure 

 m the root and in this first internode is so similar that it is prac- 

 tically impossible to separate slides with cross-sections of the one, 

 from slides with cross-sections of the other. The radial type 

 is maintained throughout the whole length of the internode. In 

 this respect our observations do not coincide with those of Potter 

 (see Proc. Camb. Soc, 4 : 1883). He says "above the node," 

 (node at which the bundles are given off to the scutellum) " we 

 •md the protoxylem the most internal part of a more or less con- 

 tinuous ring of xylem show that the rotation is complete." The 

 °nly change in the internode that we could discover was a slight 

 lateral expansion of the phloem strands. Sections cut directly on 

 the other side of the second (sheath) node show true stem struc- 

 ture both as regards the position of the elements composing the 

 Indies, and the distribution of the bundles through the mass of 

 ground tissue. 



Course of the Vascular Bundles in the Embryo. It will be most 

 convenient to trace the bundles from the root backward into the 

 m and leaves. In the root we have the true radial arrangement 

 of the xylem and phloem strands. The outer edge of both strands 

 ' uts Greedy upon the endodermis. They maintain this position 

 1 »e entire length of the root. At the first node a branch is given 



*'"; diould properly he design a I a false internode. Then le *t the insertion 



1 * " hea,h appears from the description which follows to he th. first true node, th 

 Vellum n( ,de a fahcn,.,le. 



