304 THE UNIVERSE. 



falls from heaven. It is particularly when a premature 

 winter produces a dearth in the high-lying districts that the 

 lemmings reach the lower lands. 



These emigrants are all animated with an amount of 

 courage one would not expect to find in such puny crea- 

 tures. They advance in a straight line, climb rocks, pass 

 rivers by swimming, and defend themselves against every 

 one who attacks them. Even man himself, when he bars 

 their way, does not alarm them, and they will bite his stick 

 with their feeble teeth. 



When the departure coincides with the birth of the young, 

 maternal love effects prodigies ; each mother takes a little 

 one in her mouth, and carries another on her back. 



But so much courage, energy, and perseverance generally 

 end only in disasters. The emigrants leave behind them a 

 long line of corpses ; very few ever see their mountains 

 again. Many become the prey of foxes, fish, and carnivo- 

 rous birds ; others perish in the midst of the waves, or are 

 decimated by hunger and fatigue ; sometimes even death 

 mows them down in such prodigious numbers that the very 

 air is infected with them. 



CHAPTER II. 



MIGRATIONS OF BIRDS. 



No animals display so much power and instinct in their 

 distant excursions as birds ; their migrations are really some- 

 thing marvellous. It is only by the aid of accurate instru- 



