246 



PRACTICAL BOTANY. 



of eosin in water. After a time remove, rinse in water, 

 and make transverse cuts at gradually increasing distances 

 from the lower end. In what tissues did the colored 

 solution rise the highest ? Make also longitudinal sec- 

 tions of a piece of stem similarly treated. 



c. Remove a zone of bark and the youngest layer of 

 wood from a Willow branch, leaving the bark intact for 

 about two inches on the lower end. Place in water so 

 that the peeled portion and about an inch of the bark 

 above it are wholly covered with water. The branch 

 grows and forms new roots from the bark above, but none 

 from the bark below the peeled portion. This proves 

 that the nutrient materials for the roots descend in the 

 bark portions. 



27. Plants do work. 



a. Plants not only raise their aerial portions into the 

 air against the force of gravity, 

 and carry up food material from 

 the soil, but they can carry up 

 weights attached to the branches. 

 The roots force their way down- 

 ward into the soil in some cases 

 against great resistance. The split- 

 ting and moving heavy stones by 

 the roots of trees are familiar ex- 

 amples. 



b. Counterpoise a delicate beam 

 balance, using damp sand for the 

 purpose in both pans. By the side 

 of one pan support in the horizon- 

 tal position a Bean seedling with 

 a radicle half an inch long, with 

 the radicle lying lightly but not 

 pressing upon the pan of the balance. The Bean itself 

 should rest in a drop of water, and the whole should be 



Fia. 171. Arraugement of 

 apparatus for measuring 

 the work done by the 

 radicle of a seedling. 

 (After Mangin.) 



