320 TEXTBOOK OF BOTANY 



from opium. Cocain is obtained from the leaves of the 

 coca tree. The leaves themselves are chewed by the people 

 of Bolivia and other South American countries. Cola nuts 

 are chewed by the natives of Africa. The tree that bears 

 them grows in western Africa, the West Indies, and Brazil. 



FIG. 177. A field of tobacco. 



The nuts contain a large proportion of caff ein and some theo- 

 bromin. Areca nuts (or betel nuts), the seeds of a palm, 

 are chewed in India and other Asiatic countries. Hashish, 

 prepared from the dried leaves of the hemp, is used for 

 smoking and also in the preparation of a beverage. 



338. Oils. The oils which are stored in fruits, seeds, and 

 other parts of plants belong to the class known as fatty oils. 

 A fatty oil is- characterized by the fact that on treatment with 

 a dilute alkali, such as caustic soda or potash, it forms a soap 

 and glycerin. The fats of animal bodies belong to this 

 same class of fatty oils. Various vegetable oils are used in 



