28 STEMS 
NMonocotyledonous Stems. 
Exp. 19: Piace the cut ends of two Trillium or man- 
drake stems into a weak solution of eosin. After 24 
hours make cross and longitudinal sections of the stems 
with your scaipel. The structures thru which the eosin 
rose are called fibro-vascular bundles. Do you find them 
equally distributed thruout the stem? How long are 
they? Beginning at the cut end, trace several Siete 
bundles as far up the stem as possible. Do they branch? 
Where do they end? ‘This can be ascertained by study- 
ing a small piece of a leaf under the low power. Describe 
the distribution of the coloring matter in the leaves. Con- 
clusions? 
Monocotyledonous stems are composed of scleren- 
chyma fibres forming a hard rind around the outside, 
fibro-vascular bundles scattered thruout the stem, and 
pith filling in the spaces between the bundles. Note these 
tissues under a hand lens 1n cross sections of a corn stem, 
and make an outline drawing representing their distri- 
bution. 
Histology of Monocotyledonous Stems. 
Make very thin cross sections of a piece of a corn 
stem preserved in alcohol. Study them under the high 
power and draw three or four sclerenchyma fibers and 
as many pith cells. The fibro-vascular bundles of the 
monocot stems are homologous with the wood and bark 
ot the dicot stems. They are composed of two kinds of 
tissue, xylem and phloem. The xylem is homologous 
with the wood tissue of the dicot stems, and is composed 
of fibers and vessels. The three or four large openings 
