25 



In Charce the lateral rays are shorter than the leaf and form a more 

 or less perfectly developed circle about the leaf; here they are called 

 bracts. These lateral rays or bracts are always simple cells in which 

 no farther development takes place. We must now examine the 

 basilar node of the brad, which is as important in the development of 

 the cortex of the leaf and of the fruit as the basilar node of the 

 leaf is in its development of various organs. 



The (peripheral) cell of a leaf-node subdivides, by a fissation par- 

 allel to the axis of the leaf, into a superficial and deep cell; the lat- 

 ter again subdivides in the same way, so that there are throe cells, 

 one on the other; the external cell grows out into a more or less 

 elongated bract, the internal cell remains in the node undeveloped ; 

 the median cell forms the basilar node of the bract and divides into 

 four cells in regular order first, the upper left, second, upper right, 

 then lower right, then lower left, closing the circle. In Ch. gymno- 

 pus and sub-species four additional cells develop between the four 

 first cells and a circle of eight cells results. In Ch. crinita, how- 

 ever, only two cells develop, one above and one below. 



These basilar nodal cells of the bract may not develop farther : 

 in this case the leaf remains naked, no cortex developing on it, or 

 they may grow in length with the elongating internodal cell of the 

 leaf and form a cortical envelope. 



In the median nodes of the leaf cortex cells extend upward and 

 downward to meet the extended cells from adjoining nodes ; in the 

 uppermost node no extension upward takes place on the tip, only 

 downward to meet the rising cortex cells from the node below; thus 

 it happens that in the middle of each internode of a leaf there is a 

 line of union of the cortex cells, and as there is no deviation of the 

 cells of the internodes the union is opposite, and not, as in the case 

 of the internode of the stem, alternate. On the lowest internode, only 

 the downward cortex cells are seen, no cells rising from the node of 

 the stem to cover the leaf, except in the rare instance of the European 

 Ch. ceratophylla, Willd. (see Fig. 31), in which a partial system of 

 cortex for the leaves develops in the stem-node. Fig. 32 is a leaf of 

 Ch. crinita (x5o) showing "s," two stipules at the base of a leaf; 

 "1," the first node of the leaf covered almost to the base with the cor- 

 tex from the first node ; usually these cortex cells extend the whole 

 length of the internode, but sometimes, as in this instance, the inter- 

 node is imperfectly covered ; "2," the second internode, showing the 

 line of union of the cortex cells from the first and second nodes. In 

 this species there is a single cortex cell from each bract and the leaf 

 (like the stem) is " haplostiche corticata" 



