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Home Nature- Study Course. 



in factories. Very busy factories they are, and silent ones. They are 

 mainly in the leaves of plants. The leaves must be green and of a very 

 healthy growth or the factories will get out of repair. Some of the 

 raw material that is used comes from the soil, but more of it comes from 

 the air. 



The power to run the factories comes from the sunbeams. — ^You are 

 all familiar with the sight of house plants bent toward the window. 

 That is because they are reaching out to get the power in the sunbeams 

 to run the factories in their leaves. The power in the sunbeams is greatest 

 in the summer when the freckles come on faces and tan on bare feet. 

 In winter, even though the moisture and temperature of the greenhouse 

 are made just right, the starch factories are not so active as in summer. 

 The shorter and cloudier days afiford part of the reason and the glancing 

 of the sun's rays is another and greater one. The teacher who has 

 studied physical geography may explain to her pupils why the rays of 

 light become more vertical — more up and down — as the days become 



longer. 



LESSON LXXXIX. 



Purpose. — To interest the pupils in starch as a plant product and 

 as a food for man. 



Experiment. — The iodine test for starch in potato, corn, etc. For 

 suggestions on this lesson see " First Studies in Plant Life," pp. 109-120. 



Chapter XII in "The 

 Great World's Farm." 



The products of the 

 factories are mostly 

 starch. All the starch 

 the world has ever 

 known has been made 

 by plants. The greatest 

 chemist who ever lived 

 could not make enough 

 starch to stiffen his own 

 shirt collar, yet every 

 summer tons and tons 

 of it are made by the 

 busy plants all about us. 

 All the life in the 

 world depends on starch. It is the foundation food. When in the plant 

 it is capable of going through a number of changes, much as water can 

 change to vapor, steam, now, ice, — but to a chemist, whatever the change 

 or form may be, it is always water. The starch grains which are made 



The boy professor.' Noxv adds fourteen parts zvatcr. 



