440 THE HUMAN BODY 



They are not dangerous in the sense that alcohol is, through 

 an increasing craving which readily leads to overindulgence and 

 resulting disaster, although they, like alcohol, are often taken 

 to excess. Temperance in the use of these beverages is as much 

 the part of wisdom as in the use of alcohol. Again, like alcohol, 

 they are best left alone during early life. 



The improper preparation of tea and coffee, by boiling them in 

 water, carries into solution, in addition to the stimulating prin- 

 ciple, a substance, tannin, whose effect upon the system is apt to 

 be distinctly harmful. These beverages should therefore always 

 be prepared by methods which do not involve prolonged or even 

 brief boiling while the tea leaves or coffee grounds are actually 

 present in the liquid. 



Food Poisoning. There are several conditions under which 

 foods, instead of being of benefit to the Body, may become ac- 

 tually harmful. They need to be guarded against, both by in- 

 dividuals and by the public. The latter because, with the present 

 organization of society, virtually all foods pass through many 

 hands before they finally reach the consumer, and there are cor- 

 respondingly many possibilities of contamination. The deliberate 

 introduction into foods of injurious adulterants is probably much 

 less common than some people have supposed. Unintentional 

 contamination may occur, although it is much less likely under 

 modern scientific conditions than formerly when rule-of-thumb 

 methods obtained. A historical example of accidental contamina- 

 tion was the ergot poisoning that used occasionally to ravage 

 certain parts of Europe. Ergot is a poisonous constituent of a 

 parasitic growth sometimes found on rye. When the affected 

 grain was made into rye flour and eaten regularly over a long pe- 

 riod, whole populations underwent typical ergot poisoning. The 

 symptoms were in many respects similar to those of leprosy; dry 

 gangrene, with loss of fingers and toes, and ultimate death. 



More dangerous, because more difficult to guard against, are 

 chemical changes that may occur in food between the time of its 

 preparation and its consumption. These are usually the result of 

 bacterial growth within the food mass, this growth giving rise to 

 toxins as waste products in much the same manner as does the 

 growth of pathogenic organisms within the Body. There are at 

 least two conditions of poisoning from such toxins. The first is 



