PLANT PRODUCTS 263 



half an hour or more. Now cover with water in which 

 you have put a little potash, and boil again. Pour off the 

 liquid. The pulp that is left is chiefly cellulose. 



One more substance may be found in plants. Here is 

 a green leaf. Just how much starch, sugar, oil, and pro- 

 teid it may have in it we do not know. But we do know 

 that it has something besides these. Place the leaf in a 

 bottle or tumbler and pour a little clear alcohol over it. 

 Cover the bottle or tumbler to prevent the evaporation of 

 the alcohol. Examine the next day. What has hap- 

 pened? The green coloring matter that the alcohol has 

 dissolved out of the leaf is chlorophyll. We shall find out 

 something about the value of this substance in a later 

 lesson. 



Where do the plants get all of these substances? A 

 discussion of this question will bring out the fact that 

 plants manufacture them. They may then be called plant 

 products. It will add interest to the work to have the 

 pupils make a collection of these plant products. These 

 should be put into bottles and carefully labeled. The 

 following are the products most available for this purpose: 



Starch — from corn or potatoes. 



Sugar — ordinary cane sugar. 



Oil — linseed, cottonseed, corn. 



Proteid — corn, beans, peas. 



Fiber — cotton, flax. 



Cellulose — prepare from stems or hulls of corn. 



Chlorophyll — obtain by placing green leaves in alcohol. 



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