BIOLOGY APPLIED TO HEALTHFUL LIVING 551 



(2) they are not needed by young and healthy persons, and 

 are dangerous to them in so far as they tend to create a 

 habit ; (3) in certain cases of disease and weakness they are 

 useful in quantities to be prescribed by physicians ; (4) when 

 taken habitually, it should be only at meals ; and, as a rule, 

 only with the last meal of the day, or soon after it ; (5) alco- 

 holic drinks of all kinds are worse than useless to prevent 

 fatigue or the effects of cold, although they may at rare times 

 be useful as restoratives; (6) they are almost always a 

 useless expense ; (7) their use in excess is the cause of much 

 disease, suffering, and poverty, and of many crimes; (8) 

 excessive use is sometimes the result, rather than the cause, 

 of disease. 



479. Effects of Tobacco. Concerning the effect of 

 tobacco in its various forms upon health, there has been 

 much discussion. As is well known, the stem and leaves of 

 the tobacco plant contain a poisonous substance known as 

 nicotine, which, in concentrated doses, quickly kills small 

 animals. However, this proves nothing regarding the effect 

 of smoking tobacco, or of the disgusting habit of chewing it, 

 which is now almost unknown among the better classes of 

 people ; for in both of these ways of using tobacco the nico- 

 tine is exceedingly diluted, as is the poison found in tea and 

 coffee. The result is that the effects of tobacco are not 

 marked, and so even physicians are not always certain as to 

 its influence upon their patients. The best established 

 knowledge we now have is that indigestion, irritation of the 

 respiratory organs, and heart and nervous disturbance 

 may in some people result from the use of tobacco, while 

 others show no apparent effect. 



All this refers to healthy adult men, for all medical authori- 

 ties agree that tobacco is always harmful to growing boys, 

 and interferes with their physical and mental development. 

 All schoolboys know how rigidly most athletic trainers 

 forbid the use of tobacco by those in training. 



