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 stifEer 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 Monoeotyledonous Stems. 

 — Place in red ink the ends of pieces cut from any obtainable mono- 

 eotyledonous 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. Kxamine the out surfaces and 

 the outside of each stem with the glass, and describe exactly the dis- 

 tribution of the coloring-matter. 



' If the class is studying this subject during tlie autumn, fresh pieces of com- 

 stalk will be found to give excellent results. 



