540 APPLIED BIOLOGY 



in many other ways man has ceased to be natural (e.g., cook- 

 ing food is certainly unnatural for animals), and with advan- 

 tage to himself. Clearly the use of stimulants and nar- 

 cotics must be judged by their good or bad effects upon men, 

 and not rejected simply because animals do not use them. 

 The experience of animals indicates that man does not abso- 

 lutely need stimulants and narcotics ; but it has no bearing 

 whatever on the question of whether man may or may not 

 profitably make use of such substances. This will be dis- 

 cussed at various places in the following sections. The 

 general conclusion is that under some conditions there is need 

 of stimulation, or of quieting organs by narcotics ; but that, 

 on the whole, stimulants and narcotics are easily used in 

 excess. 



465. Examples of Stimulants and Narcotics. Alcohol 

 in small quantities is a stimulant which increases the activi- 

 ties of many organs. It is well known that alcohol in 

 large quantities produces a narcotic effect, leading to the 

 complete stupor of intoxication. Opium is well known as 

 a powerful narcotic which quiets active organs, and in large 

 doses leads to a fatal sleep. Most users of tobacco in any 

 form claim that it has a soothing effect, i.e., is a narcotic. 

 Tea and coffee contain substances which are usually stimulat- 

 ing to most persons. Many drugs used by physicians (e.g., 

 strychnine, nitro-glycerine) are powerful stimulants, and 

 are given in exceedingly small quantities. When powerful 

 narcotics are demanded as relievers of pain, physicians 

 commonly use opium and its products (laudanum, morphine). 



466. Alcohol and Common Alcoholic Fluids. The forma- 

 tion of alcohol from sugar has already been described in 

 250, 251, which deal with fermentation caused by the yeast- 

 plant. Practically any natural substance which contains 

 starch or sugar may undergo fermentation. Thus juices 

 expressed from grapes, apples, and other fruits, and the 

 carbohydrates in grains of rye, corn, and barley, and in 



