Fruits and Seeds 263 



the larger part of the food of all human beings. Seeds of cotton, 

 corn, and coconut furnish enormous quantities of oils used in the 

 manufacture of various fats and soap, and nuts of various kinds 

 are coming to be used more and more extensively as foods. Corn 

 oil is widely used in the making of a rubber substitute. Flax- 

 seed is the source of linseed oil, which is used in the manufac- 

 ture of paints. From the grains we derive also starch, glucose, 

 alcohol, ether, and many related organic substances. The seeds 

 of the coffee and cacao plants supply pleasant and mildly stimu- 

 lating drinks. The hairy covering of the cottonseed is the most 

 important fiber used in the manufacture of cloth. 



PROBLEMS 



1. WTiy does a corn plant growing alone produce imperfect ears? 



2. When cucumbers are grown in commercial greenhouses, how is pollination 



accomplished ? 



3. Why are large, heavy seeds of agricultural plants more desirable for planting 



than small, light seeds? 



4. What common market " vegetables " are included in the botanical term " fruit " ? 



