THE SONG OF BIRDS 151 



complexity, but Professor Valentin Hacker, 1 who has given 

 special attention to the subject, points out that it is not 

 possible to establish a close parallelism between the com- 

 plexity of the muscular apparatus and the melodiousness 

 of the song. Thus the syrinx-musculature of the thrushes 

 (Turdidse) is in some respects less evolved than that of the 

 crows (Corvidae). As Hacker says, much must depend 

 on the differences in mental aptitude, temperament, and 

 musical taste in the various types. 



It is well known that the males are almost always better 

 singers than their mates. Indeed, some females do not sing 

 at all. Hacker's comparison of the vocal mechanism in 

 the two sexes leads him to the general conclusion that 

 the female syrinx is marked by smaller size, weaker mus- 

 culature, a more primitive skeletal architecture, and less 

 evolved vocal cords. It remains at a slightly lower grade 

 of evolution. But although the structural differences may 

 account for differences in the strength and volume of the 

 voice, they do not explain the not infrequent difference in 

 the actual character of the song. This must depend on 

 mental differences in the two sexes. 



For a few birds, such as the lapwing, it has been proved 

 that the capacity for uttering the characteristic call is 

 inborn. It depends in part on the particular peculiarities 

 of the vocal mechanism and in part on cerebral endow- 

 ments. Professor Hacker points out that birds belonging 

 to the same genus, but to different species, have often 

 certain combinations of notes in common, and he refers 

 also to the fact that a young blackbird in his first year 

 will sing a generalised thrush-song, which is not nearly 

 such a fine thing as a blackbird's. It is much to be 

 desired that careful experiments should be made to give 

 us more precise information as to what a bird can or 



1 Der Getting der Vogel, Jena, 1900, p. 19. 



