78 SCHOOL AND HOME GARDENING 



Seeds containing much oil are very valuable in commerce. 

 The oils differ in character and are used for different purposes, 

 as castor oil for medicine, linseed oil for paint, peanut and 

 cottonseed oil for food. 



The presence of oil in seeds protects them from the bad 

 effects of vireather from one year to the next. 



17. Starch in Seeds. — Remove some white starchy material from 

 different seeds, such as corn, wheat, oats and buckwheat. Treat a 

 little of each with a, solution of rather diluted iodine. The dark 

 purple color proves the presence of starch. Any other tissues may 

 be studied at the same time, as in potatoes and dry corn stalks. 



Starch in seeds makes them nutritious as food for men and 

 livestock. It is supplied by the plant for the purpose of 

 nourishing the young seedling after germination. The starch 

 is changed into sugar during germination. In this form 

 it is dissolved and can circulate through the tissues of the 

 young plant. , 



Starch is in the form of grains, each form being char- 

 acteristic of the kind of seeds or plants in which they occur. 

 By the use of a high-power microscope, the presence of differ- 

 ent kinds of starch in human food, as flours and meals, can 

 be determined. 



i8. Gluten in Seeds. — Chew a few kernels of wheat until a mass 

 of "gum " is formed. This part remaining is chiefly made up of 

 gluten or protein matter of the wheat. The starch and oil have been 

 removed by mastication. Flour is made from grinding wheat or other 

 grains. The exercise may be varied by taking a, sample of wheat 

 flour and with water making it up into stiff dough. Wrap the dough 

 in a cloth, then hold it in a pail of water and knead it until the 

 white starchy matter is washed out of it. The remaining part is 

 composed chiefly of gluten. 



Gluten is a valuable food content of grains and other seeds. 

 It is also used for food by the plant when germination takes 

 place. 



