184 METHODS IN TEACHING 



substance is now washed thoroughly in running water to 

 free it from all traces of the acid, and then thoroughly 

 dried, it is found to be quite like soot, and it may be burned 

 as other forms of carbon are burned. Pupils already know, 

 perhaps, that in digestion starch is converted into sugar. 

 The same process takes place in the ripening of some fruits 

 and in the germination of starchy seeds. See malt and beer 

 making. 



Vegetable fats, also nearly pure carbon, are obtained from 

 the seeds and fruits of many plants, notably the olive, cot- 

 ton-seed, and practically all the nuts. Other vegetable fats, 

 as turpentine and linseed oil, are important in the arts and 

 manufactures. These substances are, of course, stored up 

 for the plant's own use ; man and other animals appropriate 

 them and apply them to needs of their own. 



All plants store food in their seeds or in those parts used 



as seeds, as tubers, bulbs, spores. This stored food is 



manifestly for the use of the young plant 



Food until it becomes able to support itself. 



Substances _ , . . 



Stored by Other plants store food in quantities for 



Plants the purpose of having a large amount of 



quickly available material out of which the 

 flower-stalk, flowers, and seeds are formed rapidly in the 

 proper season. Some of these mature in one year ; as, rad- 

 ishes, lettuce, alfileria, mullein, and many others. Some 

 require two years from seed to seed again ; examples, beet, 

 carrot, onion, cabbage, celery. Still others require several 

 years, as is the case with the so-called century plant. 



Food is thus stored in the roots, as in parsnips, radishes, 

 beets, turnips; in the leaves, as in cabbage, lettuce, and 

 mullein; in the leaf bases, as in celery, onions, and lilies; 





