MEDICINAL PLANTS. 439 



Elsewhere the Bignonias open by hundreds their large and richly- 

 coloured flowers ; the Bauhinias stretch along the trees their long 

 leafless branches, often 40 to 45 feet in length, which sometimes 

 hang vertically from the lofty summits of the Swietenias, or Maho- 

 gany trees, and sometimes extend obliquely from one huge trunk to 

 another, like the ropes of a ship. The Tiger-Cats, says Humboldt, 

 display a wonderful agility in mounting or descending these graceful 

 vegetable shrouds. 



Upon the umbrageous banks of the Rio Magdalena grows a creep- 

 ing Aristolochus, whose flowers in their extraordinary development sur- 

 pass those of the Rafflesia Arnoldi, measuring often three feet and a 

 half in circumference. The forests of which we are now speaking 

 also nourish numerous species of Convolvulus ; I may particularize 

 the Convolvulus batatas, a climbing plant, whose roots produce the 

 feculent and saccharine tubercules known over the wide world by the 

 name of " Patates," and frequently but erroneously confounded with 

 that most useful vegetable, the Potato. The root of another Convol- 

 vulus, a native of Mexico, constitutes the Jalap officinalis, which 

 figures in the veterinary pharmacopoeia as an important purgative. 



Certain lianas, common enough in the South American forests, 

 belong to the family of Sapindacece, which, like the orders Loganicese 

 and Euphorbiacese, owe their reputation chiefly to the medicinal or 

 poisonous substances extracted from them. Among the Sapindaceae 

 I shall mention only the genus Paullinia, which includes several 

 species endowed with narcotic properties. These properties appear 

 especially developed in the Paullinia pinnata. Its bark, leaves, and 

 fruit contain an abundant acrid principle with which the Indians of 

 Brazil prepare a slow but certain poison. The Indians of Guiana 

 extract from the Paullinia cururu another substance with which 

 they envenom their arrows, and which was long supposed to be the 

 veritable Wourali. But Sir Richard Schomburgk has shown that 

 the latter formidable poison is really extracted, as I have already 

 recorded, from the Strychnos toxifera, a shrub of the family Logani- 

 acece, which flourishes in Guiana and Brazil. To the same family and 



