CHAPTER VI 

 THE PATH OF LIQUIDS IN THE PLANT 



59. The Problem Stated. — We have seen that plants 

 are continually losing water by transpiration, chiefly from 

 the leaves, and making good the loss by absorption through 

 the roots. The question now arises as to how the water 

 passes through the stem to the leaves. Does it pass 

 through the entire tissue of the stem, or is it confined to 

 definite regions or channels? 



60. Demonstration of Channels. — It will be easy to 

 solve our problem experimentally by placing various 

 stems or branches in liquid containing some coloring 

 substance which will stain the tissues through ^which it 

 passes. Common red ink may be used for this. Into 

 water, colored with red ink, may be placed young seedling 

 corn plants, stalks of celery, seedhngs of castor-oil plants, 

 leaves of plantain and lily, parsnips with a portion of 

 the small end cut away, or any other available material. 

 After the stems have been allowed to stand in the ink 

 solution over night, they should be thoroughly rinsed, to 

 remove the stain from the surface, and then examined 

 by cutting off a small portion of the submerged buds. It 

 will be clearly seen that the red coloring matter is not 

 deposited throughout the tissue, but is confined to 

 clearly marked channels — the fibro-vascular bundles. These 

 bundles will be found to be distributed differently ac- 

 cording to the kind of plant or its age, or both. Two 



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