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Ch. XLII.] 



DEVASTATIONS CAUSED BY LOCUSTS. 



441 



consumed 



almost all the remainder. In the accounts of the invasions 

 of locusts, the statements which appear most marvellous relate 

 to the prodigious mass of matter which incumbers the sea 

 wherever they are blown into it, and the pestilence arising 

 from its putrefaction. Their dead bodies are said to have 

 been, in some places, heaped one upon another, to the depth 

 of four feet, in Eussia, Poland, and Lithuania ; and when, in 

 Southern Africa, th(^y were driven into the sea, by a north- 

 west wind, they formed, says Barrow, along the shore, for 

 fifty miles, a bank three or four feet high.^ But when Ave 

 consider that forests are stripped of their foliage, and the 

 earth of its green garment, for thousands of square miles, it 

 may well be supposed that the volume of animal matter pro- 

 duced may equal that of great herds of quadrupeds and flights 

 of large birds suddenly precipitated into the sea. 



The occurrence of such events at certain intervals, in hot 

 countries, like the severe winters and damp summers return- 

 ing after a series of years in the temperate zone, may affect 

 the proportional numbers of almost all classes of animals and 

 plants, and probably prove fatal to the existence of many 

 which would otherwise thrive there ; while, on the contrary, 

 the same occurrences can scarcely fail to be favourable to 

 certain species which, if deprived of such aid, might not main- 

 tain their ground. 



Although it may usually be remarked that the extraordinary 



increase of some one species is immediately followed and 

 checked by the multiplication of another, yet this does not 

 always happen ; partly because many species feed in common 

 on the same kinds of food, and partly because many kinds of 

 food are often consumed indifferently by one and the same 

 species. In the former case, where a variety of different 



r 



animals liave precisely the same taste^ as^ for example^ when 

 many insectivorons birds and reptiles devonr alike some 

 particular ^j or beetle, the nnusnal numbers of these insects 

 may cause only a slight and almost imperceptible augmen- 

 tation of each of these species of bird and reptile. In the 

 other instance, where one animal preys on others of almost 



* Travels iu Africa, p. 257, Kirby and Spence, vol. i p. 215, 



