162 



nil- MARAT] 1 M.l S 



whose apex is still undivided. ('. shows the apices of the stem and second leaf, the 

 former being show n on a larger scale in (/'. The section <>t the cotyledonary bundle, 

 lying to the right of the stem apex, is plainly evident in section (',. D shows the 

 separated bundles of the cotyledon and very young second leaf, which lower down 



unite into a single strand. 



Whether we can properly speak of a stem at all in connection with the tissues 

 composing the central region of the young sporophyte is questionable. It is per- 

 fectly evident that this central region is composed partly of tissue belonging to the 

 base of the cotyledon, which is in no sense to he looked upon as an adjunct of the 



Fig. 146. -Ten transverse sections of a young sporophyte of Danaa jamaicensis. 



A-C. Thi m apex, which is shown in B F-J. Show the condition of the vascular strand in the lower 

 and more highly magnified in D. Fig. C is reversed in region of the sporophyte. 



position with reference to A. H, I. Are in the transition region. 



L. The central region of C. J. Shows the root stele. Xzoo. 



stem, and partly of the root base; the two structures, i. e., the bases of the root and 

 the cotyledon, merge insensibly into each other. To this tissue, derived from the 

 root and the cotyledon, must be added a large amount ol superficial tissue derived 

 originally from the foot of the embryo. In speaking of the axis of the young sporo- 

 phyte as a "stem" it must therefore be borne in mind that this stem is really a 

 composite structure, partly leaf, partly root, and partly foot. 



Fig. 138, A and B, shows two longitudinal sections of an older stage after the 

 emergence of the cotyledon. A passes through the stem apex and it is evident 

 that there is no vasculai bundle extending into the stem. The tracheaiy tissue is 

 now well developed in the leaf trace. B shows the trace from the second hat 

 at its point of junction with the bundle from the cotyledon. In fig. 138, C is a similar 



