ON THE SINGING OF BIRDS. 373 



to this is, that the origin of the notes of birds, 

 together with its gradual progress, is as difficult 

 to be traced, as that of the different languages 

 in nations. 



The loss of the parent cock at the critical 

 time for instruction hath undoubtedly produced 

 those varieties, which I have before observed 

 are in the song of each species ; because then 

 the nestling hath either attended to the song of 

 some other birds ; or perhaps invented some 

 new notes of its own, w hich are afterwards per- 

 petuated from generation to generation, till simi- 

 lar accidents produce other alterations. The 

 organs of some birds also are probably so defec- 

 tive, that they cannot imitate properly the pa- 

 rental notes, as some men can never articulate 

 as they should do. Such defects in the parent 

 bird must again occasion varieties, because these 

 defects will be continued to their descendants, 

 who (as I before have proved) will only attend 

 to the parental song. Some of these descend- 

 ants also may have imperfect organs; which 

 will again multiply varieties in the song. 



The truth is, as I have already observed, that 

 scarcely any two birds of the same species have 

 exactly the same notes, if any are accurately 

 attended to, though there is a general resem- 

 blance. 



