96 PRACTICAL COURSE IN BOTANY 
Ill. STEM STRUCTURE 
A. Monocoryits 
Mareriat. — Fresh cornstalks with several well-developed nodes, 
some of which should have stood in coloring fluid from 1 to 3 hours. If 
fresh specimens cannot be obtained from the fields, a number of seedlings 
may be grown in boxes of rich earth and cared for by the pupils either at 
home or in the schoolroom; they should be planted 4 or 5 weeks before 
needed. Asparagus and smilax sprouts may be used, or the stem of any 
large grass, or of wheat and other grains, but stalks of corn or sugar cane 
make the best subjects for study where they can be obtained. 
AppLtiances.— A compound microscope will be needed for detailed 
study. Prepared slides can be used, but it is better for students to make 
their own sections where practicable. 
110. Gross anatomy of a monocotyl stem. — Obtain a 
fresh cornstalk, — preferably one that has begun to tassel, — 
and observe its external characters. How are the inter- 
nodes divided from one another? What 
is the use of the very firm, smooth epider- 
mis? Notice a hollow, grooved channel 
running down one side between the joints, 
Z or nodes ; does it occur in all of them? 
Fre.112.—Cross Is it on the same side or on the opposite 
Meee oo frowue Sides of alternate internodes? Follow one 
cular bundles; ¢,cor- of these grooves to the node from which 
oha  at it originates; what do you find there? 
After studying the internal structure of the stalk, you will 
understand why this groove should occur on the side of an 
internode bearing a bud or fruit. 
Cut a cross section midway between two nodes, and ob- 
serve the composition of the interior; of what does the bulk 
of it appear to consist? Notice the arrangement of the 
little dots, like the ends of cut-off threads, that are scattered 
through the pith; where are they most abundant, toward the 
center or the circumference? 
Make a vertical section through one of the nodes. Cut a 
thin slice of the pith, hold it up to the light, and examine 
