292 EXPERIMENTAL GENERAL SCIENCE 



him a pleasurable feeling of restfulness and bodily comfort 

 by partially stupefying the nervous system. Such drugs are 

 called narcotics. Other narcotics may first act as stimulants 

 and, by driving the cells of the body at a faster pace than 

 normal, produce a feeling of ease and lightness of spirits which 

 some people find attractive. Sooner or later, however, there 

 comes a reaction in which the body pays for its past excesses 

 by a feeling of dullness and depression until the person again 

 partakes of the drug which renews the feeling of pleasurable 

 elation. When once the use of such substances is begun, 

 however, a craving is soon developed which can only be satis- 

 fied with new and often larger amounts of the same substance, 

 and thus a habit is formed which is difficult or practically 

 impossible to break. The commonest of the drugs containing 

 alkaloids used by man are tea, coffee, cocoa, chocolate, opium, 

 morphine, cocaine and tobacco. Of these, opium, morphine, 

 and cocaine are such harmful drugs that their sale to persons 

 other than physicians is wisely forbidden by law in most States. 



250. Tea, Coffee and Other Beverages. Tea, coffee, cocoa, 

 and chocolate are almost universally used as beverages and 

 in the quantities ordinarily taken seldom cause harm, though 

 all contain 'alkaloids very similar in their effects upon the 

 body. Of the four, coffee has the greatest amount of alkaloid 

 and its use in excess often causes wakefulness, especially in 

 those unaccustomed to its use. Cocoa and chocolate, owing 

 to the way in which they are prepared for the table, have 

 considerable value as food. Tea and coffee, however, are 

 not needed by growing children and their use by them should 

 be discouraged. Except for the sugar and cream they con- 

 tain, they have no food value. In adults, however, they serve 

 to stimulate the flow of the digestive juices and by their flavors 

 may make the food more palatable. 



251. Tobacco. The effect of the alkaloid in tobacco is 

 secured through smoking or chewing it, or using the powdered 

 tobacco as snuff. Various other plants have been used for 



