338 THE UNIVERSE. 



to be at hand to lend them refuge. During one of 

 my wanderings across the Mediterranean, some strayed 

 swallows happened, when we were mid-way between the 

 two coasts, to fall totally exhausted on the deck of the 

 frigate which was carrying me towards Africa. Every- 

 one on board, soldiers and sailors, overwhelmed them with 

 attentions, which they received without exhibiting signs of 

 fear. When they had at last recovered from their fatigues, 

 they recommenced their journey towards the high regions 

 of Senegal, and perchance rested beneath the cabins of 

 savages long ere we had greeted the ports of Algeria. 



But after long and perilous journeys these charming 

 visitors of our dwellings return each year with touching- 

 fidelity to find their old domicile again. If the rains and ' 

 winds have injured it, the architects quickly repair it before 

 making it witness of their loves. Spallanzani has even no- 

 ticed that the feathered couples become strongly attached 

 to their particular nests. Having fixed party-coloured 

 ribbons to the feet of some of them, he recognized them 

 the year after, when they came to take possession again. 

 He saw them return thus for eighteen successive summers. 

 How many among us never enjoy such a long tenancy! 



Another species of the same grou^), the ariel swallow, 

 fondly returns to its republic, formed of agglomerated nests, 

 and more ingeniously constructed than those of our swal- 

 lows. These nests resemble so many wide-necked bottles 

 hung by the bottom in inaccessible places. 



Less remarkable for the instinct which guides them than 

 for the innumeral:)le multitude of their army, the passenger 

 pigeons {Cnlwiaha mUjratoria) traverse the forests of Ame- 

 rica in such compact masses that tliey absolutely intercept 

 the rays of the sun, and cast a long track of shadows on 

 the ground. Their compact columns extend over such a 



