FIELD AND LABORATORY EXERCISES 11 



up the surplus soil moisture. This checking of the growth of 

 the trees will allow the plant to better protect itself from winter 

 killing. 



Plants store up food for the early spring development. Ex- 

 amples of these are found in all seeds and fruits, in the stems of 

 plants and in underground parts. The stored parts of plants may 

 form food for animals and man. This is illustrated in beets and 

 in other root crops, in corn, wheat, oats and other grains. The 

 sap from sorghum cane is used for making syrups because of the 

 sugar stored there by the plant. 



FIELD AND LABORATORY EXERCISES 



1. Sugar and Starch. Test the stems of corn or sorghum for sugar and 

 starch. The same test may be made with twigs and buds of the apple or 

 other woody plants. Starch may be detected by a drop of iodine on the cut 

 surface. The color will change to blue or purple if starch is present. Sugar 

 may be detected in beets, sorghum stems and other tissues by the use of a 

 little copper sulfate solution on the cut surfaces. In a few moments rinse 

 this off. Then heat the tissue on a glass slip over a flame after adding a few 

 drops of very strong potassium hydroxide. If sugar is present a blue colora- 

 tion will gradually appear in the liquid. 



2. Test for Oil. Examine the seeds of a castor-oil plant, flax, cottonseed, 

 soy beans, peanut or others for oil. In soft seeds the presence of the oil may 

 be detected by pressing it between two layers of paper or between the fingers. 

 If a chemical test is desired use henna root dissolved in alcohol. This solution 

 is called alcanin. Drops of oil or fat will be stained red by alcanin. 



3. Examining Starch. If a high power microscope is available a useful 

 study may be made of the different kinds of starch found in seeds. Compare 

 the grains of such seeds as rice, wheat and corn with those of the potato tuber. 

 Then examine a few samples of flour to see if more than one kind of starch is 

 present. It is not an uncommon thing to find some corn starch present in 

 wheat flour. What is the probable source of the grains found in laundry starch? 



4. Moisture and Germination. Students should carefully read over 

 exercises showing the effect of moisture on germination, warmth influencing 

 germination and the necessity of air in germination. Exercises of this charac- 

 ter are outlined in the writer's book on School and Home Gardening. If this 

 or similar exercises have not been performed by the students, they should be 

 taken up in connection with this chapter. 



5. Sprouting at Different Depths. An exercise on depth of planting is 

 outlined in "Productive Farming." This may be repeated. 



6. The Effect of Sunlight in producing green color in leaves should be 

 tried. A simple way to prove the effect of sunlight in producing green color 

 is shown by placing a light board over a plot of grass for a few days. Then 

 notice the bleached appearance of the grass leaves. 



7. Window Aquarium. In connection with the paragraph on plants, 

 the student should start a self-balanced aquarium by putting into a two- 

 quart glass jar or gallon jar a little clean sand and gravel. Then a supply of 

 water plants from stagnant pools, such as algae, duck weed, Nigella and 

 others; then a few water insects and a few minnows, and place the glass jar 

 in direct sunlight, as in a south window. See description of such an aqua- 

 rium in School and Home Gardening (Fig. 3). 



