r 50 Campbell . — The Gametophyte and 
This type of apical cell is found in most species of Ophioglossum , and 
in many Marattiaceae, but is unlike that of either B. virginianum 
or B. Lunar ia. 
Very soon after the cotyledon a$d stem apex are recognizable, the 
second leaf arises as a group of meristem cells close to the stem apex. The 
Text-fig. 7. A. Two longitudinal sections of an embryo, cut in the plane of the cotyle- I 
don, cot. The root, r., is very conspicuous, st., stem apex. x 100. B. Two sections of a 
similar embryo, cut in a plane at right angles to that of A. 1 shows the leaf-traces of the | 
cotyledon and second leaf. c. Somewhat oblique section of an older embryo showing the con- f; 
spicuous sheath, sh., at the base of the cotyledon. 
vascular bundle belonging to the second leaf is formed very early and joins 
the primary bundle extending through the cotyledon and root. The stem 
apex occupies the space between these bundles, but has no procambium 
tissue developed from it. The relation of the vascular bundles to the 
leaves and stem apex is best seen in a series of cross-sections (see Text- 
%• i°)- 
