356 LYCOPODITJM. 



capsules, one seated on the base of each of the broad 

 spirally arranged leaves (sporophylls) of the cone the 

 rij)e sporangia is yellow and opens by a transverse slit. 



500. Structure of Stem. In transverse sections 

 of the stem note (1) the epidermis, with thick cuti- 

 nised outer walls; (2) the sclerenchymatous outer cortex; 

 (3) the thin-walled parenchymatous middle cortex ; (4) 

 the sclerenchymatous inner cortex; (5) the leaf-trace 

 bundles, lying here and there in the cortex, through which 

 they pass from stem-stele to leaf; (6) the "bundle- 

 sheath," several layers of thin-walled cells (the outer 

 layers with cutinised or corky walls on placing a drop of 

 sulphuric acid on a section, these cells remain unaffected 

 after the other tissues have lost their clear outlines) ; (7) the 

 xylem and the phloem, arranged in more or less horizontal 

 alternating bands, though there are often connections be- 

 tween the xylem-bands towards the centre of the stele. 



With the high power note, in the xylem, the small pro- 

 toxylem tracheids at the outside (the edges of the bands) ; 

 in the phloem, the narrow thick- walled protophloems, alter- 

 nating with the protoxylems. In both xylem and phloem 

 the main part of each band consists of wide elements. 



In radial longitudinal sections of the stem note (1) the 

 leaf-bases ; (2) the epidermis, the three zones of the 

 cortex, and the bundle-sheath ; (3) leaf-trace bundles, 

 running down obliquely from leaf to central cylinder ; (4) 

 the spiral (protoxylem) tracheids and the wide scalari- 

 form tracheids ; (5) the phloem cells, some narrow and 

 others wide the latter are the sieve -tubes, but when 

 mature they are almost empty and the small sieve-plates 

 are difficult to make out. 



501. Structure of Leaf. In sections taken across the leafy 

 stem, some leaves will be found cut transversely ; note the trian- 

 gular outline of the section (the longest side being upwards), the 

 epidermis with stomates on both upper and lower sides (examine 

 entire leaves in surface view), the spongy mesophyll, and the small 

 central vascular bundle. In transverse sections of a root, note 

 the general resemblance to the stem, but the smaller number of 

 xylems and phloems, the former being often irregular and fused 

 together, 



