8 EVOLUTION OF BIRD- SONG 



have traced family resemblances of this nature in 

 species physically allied, and in others not thus 

 related. I also read of certain birds which inherit 

 their songs, and I was acquainted with several 

 which inherit their alarm-cries and call-notes. The 

 subject to which these matters relate, the influence 

 of heredity, is discussed at length in chapter vii. 

 There can be no doubt that heredity is as certain 

 in perpetuating the cries of some species as is 

 imitation in determining the whole character of 

 the songs of others ; the extent to which these 

 influences prevail in the several orders of birds has 

 yet to be traced. Variation, towards which feature 

 the males of so many species tend, seems to be the 

 parent of imitation ; it is considered in a separate 

 chapter. 



"The Music of Bird -song" is the concluding 

 theme. It has to some extent been discussed in 

 the chapter on Imitation ; but in the Appendix will 

 be found a transcript of many strains which I 

 heard sung by the better singers. 



The reader will observe that I have not relied 

 wholly upon my own observations, but have quoted 

 those of numerous well-known authorities, of good 

 report in the scientific world. I read no book at 

 all on the subject until 1889, when I had com- 



