VII. THE PATH OF WATER IN THE PLANT: STRUCTURE 

 OF STEMS* 



A . The Function of the Stem: 



Experiment 14. To see if there are definite channels 

 for the passage of liquids through a stem. 



1. Place the cut ends of various living, leafy shoots 

 (e.g., corn, plantain, lily leaves, parsnip, or seed- 

 lings of castor-oil plants), into an aqueous solution 

 of eosin, and, after they have stood for a suitable 

 time, as determined by the instructor, observe 

 freshly exposed end-surfaces, and note the regions 

 where the colored solution appears. Does it pass 

 up through the whole mass of tissue, or are there defi- 

 nite channels through which it rises? Cut sections 

 of the stems at various heights, and observe and 

 describe the distribution of the colored areas. 



2. Compare the distribution of the colored areas in a 

 parsnip (or seedling of a castor oil plant) and a 

 stalk of corn (or petiole of some lily leaf). Make 

 a diagram to illustrate this. 



3. Examine the end of a dry corn stalk, and note the 

 projecting strands. What relation do they bear to 

 the paths of the eosin? They are composed of 

 fibers and vessels united, and are therefore called 

 fibre-vascular bundles. To what class of tissue 

 do they belong? 



4. Carefully cut the epidermis in a ring around the 

 petiole of a leaf of plantain, being specially careful 

 not to cut clear through the petiole. 



*The outline for VII, B-F (pp. 35-41), was prepared by Prof. Ernest 

 Shaw Reynolds, Agricultural College, N. D. 



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