VII. PLANT GROWTH AND NUTRITION — PLANTS 



MAKE FOOD 



Problem, — Where, wlien, and how green plants malce food ? 



(a) How and why is moisture given off from leaves ? 



(b) W1^at is the reaction of leaves to light ? 



(c) What is 'made iiv green I eaves in the sunlight? 



id) What by-products are given off in the above process ? 

 (e) Other functions of leaves. 



Laboratory Suggestions 



Demonstration. — Water given off by plant in sunlight. Loss of weight 

 •due to transpiration measured. 

 Laboratory exercise. — 



(a) Gross structure of a leaf. 



(6) Study of stoma and lower epidermis under microscope. 



(c) Study of cross section to show cells and air spaces. 

 Demonstration. — Reaction of leaves to light. 

 Demonstration. — Light necessary to starch making. 

 Demonstration. — Air necessary to starch making. 

 Demonstration. — Oxygen a by-product of starch making. 



What becomes of the Water taken in 

 by the Roots? — We have seen that 

 more than pure water has been absorbed 

 through the root hairs into the roots. 

 What becomes of this water and the 

 other substances that have been ab- 

 sorbed? This question may be partly 

 answered by the following experiments. 



Passage of Fluids up the Stem. — If 

 any young growing shoots (young seed- 

 lings of corn or pea, or the older stems 

 of garden balsam, touch-me-not, or sun- 

 flower) are placed in red ink (eosin), 

 and left in the sun for a few hours, the 

 red ink will be found to have passed up 



the stem. If such stems were examined 

 84 



Apple twigs split to show the 

 course of colored water up 

 the stem. 



