264 NOCTURNAL LIFE OF ANIMALS 



the wonderful luxuriance of the growth of its trees to 

 the combined influence of great moisture and high tem- 

 perature. In the temperate zone, and especially in 

 Europe and Northern Asia, forests may be named from 

 particular genera or species, which, growing together as 

 social plants, (plantse sociales) form separate and distinct 

 woods. In the northern forests of Oaks, Pines, and 

 Birches, and in the eastern forests of Limes or Linden 

 trees, usually only one species of Amentacese, Coniferse, 

 or Tiliacese, prevails or is predominant ; sometimes a single 

 species of Needle-trees is intermingled with the foliage 

 of trees of other classes. Tropical forests, on the other 

 hand, decked with thousands of flowers, are strangers to 

 such uniformity of association; the exceeding variety of 

 their flora renders it vain to ask of what trees the primeval 

 forest consists. A countless number of families are here 

 crowded together, and even in small spaces individuals 

 of the same species are rarely associated. Each day, and 

 at each change of place, new forms present themselves 

 to the traveller, who, however, often finds that he cannot 

 reach the blossoms of trees whose leaves and ramifications 

 had previously arrested his attention. 



The rivers, with their countless lateral arms, afford the 

 only routes by which the country can be traversed. Between 

 the Orinoco, the Cassiquiare, and the Rio Negro, astrono- 

 mical observations, and where these were wanting, determi- 

 nations by compass of the direction of the rivers, respec- 

 tively shewed us that two lonely mission villages might be 

 only a few miles apart, and yet that the monks when they 



