1908] 



DO RET Y—CERATOZAMIA 



is sent to the first leaf (fig. 22). As previously noted, this organ, 

 whether scale leaf or foliage leaf, is displaced laterally by the peculiar- 

 ities of its development. All the 

 traces which enter it are likewise 

 distorted, giving rise to a pseudo- 

 girdling condition which is appar- 

 ent in very young seedlings (figs. 

 22, 27, 31) . The two traces which 

 enter from the groups nearest the 

 leaf (e, e') take first a radial, and 

 then a tangential course to reach 

 a position in the middle of the leaf 

 (figs. 22, 31), showing on the way 

 a tendency to branch. The traces 

 (d, d') supplied from the groups 

 farther away take a tangential 

 course, each giving off vertical 

 branches, which in turn branch 

 again. The remaining traces of 

 the original four foliar bundles 

 ascend vertically (fig. 23), and • 

 branch and anastomose freely. 

 Only a limited number, in most 

 cases four or five, remain (fb, figs. 

 24, ji). Before reaching the leaf 

 base, each of these divides, one 

 member entering it (/, fig. 23), the 

 other, which remains small, being 

 directed toward the growing point 

 of the stem (u, figs. 23, 27) . Fig. 

 23 represents the branching and 

 anastomosing of these strands. 

 It should be noted that the vertical 

 scale of the three diagrams (figs. 

 21-23) is magnified considerably. 



Fig. i. — Study of foliage leaf from base 

 (a) to apex (/>); for explanation see text. 



In the younger stages there is no attempt at girdling on the part 

 of the leaf traces, except that which has been referred to in the first 



