no 



BOTANY 



layer of corky cells, which serve this purpose.* The experiment here illus- 

 trated shows this. 



Select two potatoes of equal weight and peel the skin from one. Place 

 the pared potato, with the parings, in one pan of the scales and the other 

 potato in the other pan; it will be found that the pared potato loses 

 weight very rapidly. A reco'^d of this loss of weight should be kept and 

 the results noted in tabular order. Of what use is the epidermis to the 

 potato? 2 



Passage of Fluids up M onocotyledonous and Dicotyledonous Stems. — Use 

 old seedlings of Indian corn for the monocotyledonous stem. Cut off the stem 

 close to root and place it in a solution of eosin or red ink. Place some cut 



Experiment to show that the skin of the potato retards evaporation. 



dicotyledonous stems in red ink. Garden balsam, which can be grown in 

 the hothouse or laboratory, is the most transparent. Impatiens and sun- 

 flower are also good. Leave them in the solution in a sunny room for one 

 day. In all the above cases the colored material is found to move up the 

 stem and into the leaves and flowers. Cut some of the above stems and 

 examine them closely to see where the most red ink is. Compare the distri- 

 bution of bundles in stems with their distribution in the taproot. 



Passage of Fluid up and down the Stem. — From the above 

 experiments it is evident that the course taken by water in its 

 course up the stem is confined to the collections of woody tubes 

 which we call the fibrovascular bundles. In the stem of a mono- 



J The extreme outside layer of cells, as in the root, is known as the epidermis. 

 It is often not seen in old stems. 



2 See Hunter and Valentine, Manual, page 239. 



