938 " BOTANY. 
(k) Observe the large early flowers of violets, which are dependent 
upon insects for pollination. Notice that after a while none of these 
appear, but only small ones destitute of petals. In the common yel- 
low violet these are borne on the stem above the ground, but in blue 
violets they are often underground. These small flowers are self- 
pollinated (cleistogamous). 
505. The fibro-vascular bundles of the stems of Angio- 
sperms are entirely of De Bary’s “collateral” class; that 
is, each bundle in cross-section is more or less distinctly 
two-sided, viz., wood and bark. Each of these sides gen- 
erally contains soft, fibrous, and vascular tissues. 
506. The disposition of the bundles in the Angiosperms 
is for the most part dependent upon the position of the 
leaves. Nearly all the first-formed bundles are of the kind 
termed “common bundles;” that is, they extend on the 
one hand into the leaf, and on the other down into the 
stem. 
507. The general arrangement may be illustrated by Fig. 
134, in which there pass down from each leaf three bun- 
dles; at the lower internode these are, on the left, a, 3, ¢, 
and, on the right, d,e, f. At the next internode, where 
the leaves stand at right angles to the lower ones, there 
are three bundles again, g, A, 7, and &, J, m; these are 
largest at their points of curvature, and they dwindle in 
size as they pass downward and finally unite with the bun- 
dles from the lower pair of leaves. The bundles from the 
third internode pass downward, and in like manner join 
those from the second pair of leaves, and so on. Thus in 
such a stem every bundle passes downward through one 
internode before joining another, and in any internode all 
the bundles are derived from the leaves at its summit. 
508. In some Angiosperms the bundles in a cross-section 
of a stem are separate from one another, while in others 
