42 2 TEXTBOOK OF BOTANY 



peas and cut away the endosperm of the com. Compare the 

 further growth with that of normal seedlings. 



9. Take seeds of several plants, such as beans, peas, radish, and 

 com ; divide those of each sort into three groups : large, medium, 

 and small. Plant each lot under as nearly as possible the same 

 conditions and observe the germinating seeds and seedlings from 

 time to time. Do you find that there is any relation between the 

 size of a seed and the size and vigor of the plant that grows from 

 it ? If so, which size of seed gives the best results ? 



10. If possible, secure some "seeds that were gathered before they 

 were ripe, some of the same sort gathered when they were just ripe, 

 and others that remained on the plant for some time after ripening. 

 Plant them and observe to determine the length of time needed for 

 germination and the rate of growth of the plants that grow from 

 each lot. 



Chapter XIX 



In connection with the study of this chapter, if time allows, the 

 class may well be given practice in identifying some of the common 

 wild plants. In this work, the pupil learns not only the names of 

 particular plants and their reference to the appropriate families, 

 orders, and classes ; he also learns — what is perhaps more im- 

 portant — how to identify unknown plants by means of a manual. 

 A list of some of the leading manuals available for the identification 

 of the seed plants and ferns in various parts of the United States 

 and Canada will be found in Appendix II. 



Chapter XX 



1. Make a list of twenty of the -more important plants raised 

 in your neighborhood which supply food for man. What part of 

 the plant is used in each case? What changes does the plant 

 undergo to make it suitable for use ? 



2. Name ten foods derived from plants which are imported from 

 other parts of the world. 



3. What cultivated plants growing in your neighborhood are 

 used as food for animals ? What wild plants ? 



4. What plants have you seen growing that supply fibers ? For 

 what purposes are their fibers used? What other sorts of plant 



