112 



BOTANY. 



upon a piece of paper, as it dries the spores are discharged, 

 covering the paper with the spores, which look like fine brown 

 powder. 



FIG. G8. A, vertical section of the leaf of the maiden-hair fern, which has cut 

 across a vein (/.&.) , x 150. B, surface view of the epidermis from the lower sur- 

 face of a leaf. /, vein, p, breathing pore, x 150. (7, longitudinal section of the 

 fibro-yascular bundle of the leaf stalk, showing tracheids with ladder-shaped 

 markings, x 150. D, longitudinal section through the tip of a root, x 150. 

 a, apical cell. PL young fibro-vascular bundle. Pb. young ground tissue. 



E, cross-section of the root, through the region of the apical cell (a), x 150. 



F, cross-section through a full-grown root, x 25. r, root hairs. G, the fibre- 

 vascular bundle of the same, x 150. 



A microscopical examination of the leaf stalk shows the tissues to be 

 almost exactly like those of the stem, except the inner ground tissue, 

 whose cells are thin-walled and colorless (soft tissue or "parenchyma) 

 instead of stony tissue. The structure of the blade of the leaf, however, 

 shows a number of peculiarities. Stripping off a little of the epidermis 

 with a needle, or shaving off a thin slice with a razor, it may be examined 

 in water, removing the air if necessary with alcohol. It is composed of a 

 single layer of cells, of very irregular outline, except where it overlies a 

 vein (Fig. 68, ,/). Here the cells are long and narrow, with heavy 



