64 THE FIRST BOOK OF FARMING 



the broken surfaces of the grains. Notice that it 

 turns them purple Now drop a drop of the iodine 

 on the laundry starch. It turns that purple also. 

 This experiment tells us that plants contain starch. 



Experiment. Chew a piece of sorghum cane, 

 sugar cane, cornstalk, beet root, turnip root, apple 

 or cabbage. They all taste sweet and must there- 

 fore contain sugar. 



Examine a number of peach and cherry trees. 

 You will find. on the trunk and branches more or 

 less of a sticky substance called gum. 



Experiment. Crush on paper seeds of cotton, 

 castor-oil bean, peanuts, Brazil nuts, hickory nuts, 

 butternuts, etc. They make grease spots ; they con- 

 tain fat and oil. 



Experiment. Chew whole grains of wheat and 

 find a gummy mucilaginous substance called wheat 

 gum, or wet a pint of wheat flour to a stiff dough, 

 let it stand about an hour, and then wash the starch 

 out of it by kneading it under a stream of running 

 water or in a pan of water, changing the water fre- 

 quently. The result will be a tough, yellowish 

 gray, elastic mass called gluten. This is the same 

 as the wheat gum and is called an albuminoid be- 

 cause it contains nitrogen and is like albumen, a 

 substance like the white of an egg. 



If we crush or grate some potatoes or cabbage 

 leaves to a pulp and separate the juice, then heat 

 the clear juice, a substance will separate in a flaky 

 form and settle to the bottom of the liquid. This 

 is vegetable albumen. 



