SEL AGIN ELLA SPOROPHYTE 2(i5 



elliptical bundle, it forms a continuous band sur- 

 rounding 



c. The central xylem, which appears as a spindle- 

 shaped mass of tissue when seen in transverse section, 

 and consists of elements with lignified walls, and no 

 cell-contents. 



Small vascular bundles of rounded outline, as seen 

 in the transverse section, may be found opposite or 

 near to the ends of the spindle-like vascular bundle ; 

 these are bundles of the leaf-trace cut through on their 

 course inwards from the leaves : thus the whole bundle- 

 system of this shoot consists of a single central bundle, 

 which traverses the axis longitudinally, and gives off 

 smaller branch-bundles, which pass outwards into the 

 leaves, one of them entering each leaf. 



The vascular system of the shoot is more complicated in certain 

 other species of Sdaginella, and transverse sections should be 

 made from these : thus in S. Willdonovii, S. mcequalifolia^ &c., 

 three large flattened bundles are seen in each transverse section of 

 the axis ; the planes in which these bundles are flattened are 

 parallel to one another ; in these species the bundles may indivi- 

 dually show considerable irregularities of outline : the whole 

 arrangement of their vascular system may with advantage be 

 compared with that in the stem of Lycopodium. 



Note with a higher power 



1. The general appearance of the phloem, with its 

 highly refractive cellulose walls, and scanty protoplasm. 



2. Between this and the xylem a somewhat irregular 

 series of cells of the conjunctive parenchyma, with 

 thin cellulose walls and plentiful protoplasm. 



3. The chief constituents of the xylem are large 



