66 ELEMENTS OF BOTANY. 
smaller grains and of rods of cane or bamboo is due to their 
form. It can readily be shown by experiment that an iron 
or steel tube of moderate thickness, like a piece of gas-pipe, 
or of bicycle-tubing, is much stiffer than a solid rod of the 
same weight per foot. The oat straw, the cane (of our 
southern canebrakes), and the bamboo are hollow cylinders: 
the corn-stalk is a solid cylinder, but filled with a very light 
pith. The flinty outer layer of the stalk, together with the 
closely packed sclerenchyma fibres of the outer rind and the 
frequent fibro-vascular bundles just within this are arranged 
in a most advantageous way to secure stiffness. 
89. Experiment 17. Rise of Water in Monocotyledonous Stems. 
— Place in red ink the ends of pieces cut from any obtainable mono- 
cotyledonous stem, as green brier, or young shoots of asparagus,! and 
watch for an hour or two the rise of the coloring-matter, by taking out 
pieces of stem from time to time and cutting each back from the upper 
end until the colored portion is reached. Examine the cut surfaces and 
the outside of each stem with the glass, and describe exactly the dis- 
tribution of the coloring-matter. 
1 Tf the class is studying this subject during the autumn, fresh pieces of corn- 
stalk will be found to give excellent results. 
