200 BOTANY. : 
419. The leaves are in nearly all cases supplied with 
fibro-vascular bundles, which run as veins through the soft 
tissue; there is usually a prominent midrib, upon each side 
of which are small veins, which are free (i.e., running more 
or less parallel from the midrib to the margin) or re¢icu- 
lated. Some or all of the leaves at maturity bear spore- 
cases containing spores. 
420. The ferns are all richly supplied with chlorophyll, 
and none are in any degree parasitic. Nearly all the species 
“Fic. 111.—A, the first stage of a Fern, under side; 6, root-hairs; an, antherids; 
ar,archegones. 3B, the same after fertilization, showing the growth of the fern- 
let; 0, its leaf; w’, its first root. Magnified a few times. 
are perennial; in some cases, however, dying down to the 
ground at the end of the summer, the underground por- 
tions alone surviving the winter. 
421. The first stage in the ferns is frequently somewhat 
heart-shaped, and is generally provided with root-hairs on 
its under surface, by means of which it secures nourishment 
for its independent growth (Fig. 111, A). In the Pepper- 
worts the first stage is so reduced as to be only a small 
outgrowth of the germinating spore. 
