186 MEDICINAL AND POISONOUS PLANTS 



amount by persons of mature j'ears, toliaeeo is ahvays in- 

 jurious, is a question witli regard to whicli medical opinion 

 is divided. All competent observers, however, are agreed 

 that unrestrained use invites serious ills, ])roduces enfeebled 

 digestion, heart cUsease, and nervous debility, and may lead 

 to insanity. Furthermore, all are agreed that even in very 

 small amount, toljacco in whatever form is decidedly in- 

 jurious to young persons, and that habitual use of it may 

 quite unfit them for happy, vigorous life. It is a significant 

 fact that those who are in training for athletic contests are 

 forbidden to use tobacco. 



The drug coca consists of the dried leaves of the coca shrub 

 (Fig. 174). These leaves mixed with ashes or lime are chewed 

 extensively by the Indians of western South America as a 

 means of lessening the sense of hunger and fatigue. Moderate 

 use by the native mountaineers seems not to injure them, 

 but excessive use produces effects as bad as those following 

 the abuse of opium. Foreigners are found to Ije especially 

 susceptible to the injurious properties of coca; and although 

 with us it is widelj^ used as a medicine, it nmst be regarded, 

 like opium, as an especially dangerous drug never to be taken 

 except on advice of one's physician. The effect of coca upon 

 the nervous system appears to be ilue partly to some volatile 

 substance not yet satisfactorily iletermined, and to an alka- 

 loid known as cocaine ((\7H.21NO4). This alkaloid has the 

 remarkal)le proi)erty of producing insensibilit>' to pain within 

 certain restricted regions of the l)otly to which it may be 

 applied. Thus a small amount of a weak solution dropped 

 upon the eyeball pernuts a surgeon to ojicrati^ upon that 

 organ without causing the slightest ]iain. 



Atropine (CijH.jiNO;;) is another poisonous alkaloid of im- 

 portant use in connection with th(> oyv. An exceedingly 

 minute quantity locally apphed causes the pujiil of the eye 

 to enlarge, by relaxation of the surrounding muscles, and 

 thus makes possible an examination of internal parts which 

 are ordinarily invisible. The alkaloid is obtained from the 

 leaves and roots of belladonna (Fig. 175) a very poisonous 

 plant. 



Quinine (CivIL^N.Oo) is on(> of n\any alkaloids obtained 



