The Swallow and the Sparrow 



I We will now end this digression on the 

 habits of birds and apply the evidence 

 which we have gathered to the Pelopseus. 

 Every species practising its industry in our 

 dwellings must first have practised and, we 

 maintain, must still practise it under condi- 

 tions wholly extraneous to the work of man. 

 The Wall-swallow and the Sparrow have 

 given us proofs which are all that can be 

 desired; the Domestic Swallow, more reti- 

 cent of his secrets, gave us only probabili- 

 ties, which however come very near to cer- 

 tainty. The Pelopaeus is almost as obsti- 

 nate as the last-named in refusing to di- 

 vulge her ancient customs and long remained 

 to me an insoluble problem in so far as her 

 original domicile was concerned. Where 

 can the enthusiastic colonist of our chimneys 

 have lived, when far removed from man? 

 Thirty years and more elapsed after I first 

 made her acquaintance; and her history al- 

 ways ended in a note of interrogation. 

 Outside our houses, never a trace of a Pelo- 

 paeus-nest. And all the time I was apply- 

 ing the method of analog)', which provides 

 a very probable answer to the question of 

 the Domestic Swallow; I was pursuing my 

 search in the caves, in the shelters under 

 rocks facing the sun. Not a sign. I was 

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