58 ADVANCED PHYSIOLOGY 



sorbed, but digestion proceeds more rapidly when the Juices 

 are somewhat diluted. 



Other Beverages. In America, the most commonly used 

 beverages, other than water, are probably coffee, tea, cocoa 

 and chocolate. Cocoa and chocolate are foods, since they 

 contain some fatty material. Coffee and tea, on the other 

 hand, can be considered only as stimulants. The active ele- 

 ment in coffee is a substance called caffein', that in tea is 

 called thein, the two being practically identical. The degree 

 to which these affect different individuals is variable. As a 

 rule they excite the nerve centers to greater activity. This may 

 be of advantage in rare cases; but not when one is in bed, 

 trying to sleep. After the use of these drinks becomes a 

 habit, the nerve centers refuse to act well unless urged on 

 by this "whip" and it is better to live in the strength of one's 

 own natural vigor. 



The "soft drinks" sold at soda fountains are made of watei 

 into which carbon dioxid gas has been pressed. Flavors in 

 the form of syrups are added. Since carbon dioxid is really 

 one of the waste products of the body, we might suppose that 

 in our drink it would be harmful; but it is of real injury only 

 when we breathe it. However, such drinks are no better 

 than water; they are expensive and the syrups may impair 

 digestion. Lemonade is used solely for its agreeable taste, 

 although the sugar which is usually in it serves to a small 

 degree as food. Some beverages are advertised as especially 

 "good for the nerves," but this claim is largely a pretense 

 used for the purpose of catching trade. If one finds any 

 drink especially exhilarating, he is warranted in suspecting 

 that it contains alcohol or a similar ingredient that produces 

 temporary excitement. 



Alcohol. Alcohol must be considered here because it has 

 so often been classed as a food, and has even been given the 

 unfortunate misnomer, "liquid bread". Alcohol is derived 

 from sugars by a process of fermentation. A large number 



