Chap. XIX. . MUSICAL POWERS. 331 



fected in relation to the propagation of the species. 

 Insects and some few spiders are the lowest animals 

 which voluntarily produce any sound ; and this is gene- 

 rally eftected by the aid of beautifully constructed 

 stridulating organs, which are often confined to the 

 males alone. The sounds thus produced consist, I believe 

 in all cases, of the same note, repeated rhythmically ; ^^ 

 and this is sometimes pleasing even to the ears of man. 

 Their chief, and in some cases exclusive use appears to 

 be either to call or to charm the opposite sex. 



The sounds produced by fishes are said in some cases 

 to be made only by the males during the breeding 

 season. All the air-breathins: Vertebrata necessarily 

 possess an apparatus for inhaling and expelling air, with 

 a pipe capable of being closed at one end. Hence wdien 

 the primeval members of this class were strongly ex- 

 cited and their muscles violently contracted, purpose- 

 less sounds would almost certainly have been produced ; 

 and these, if they proved in any way serviceable, might 

 readily have been modified or intensified by the pre- 

 servation of properly adapted variations. The Amphi- 

 bians are the lowest Vertebrates which breathe air ; and 

 many of these animals, namely, frogs and toads, possess 

 vocal organs, which are incessantly used during the 

 breeding-season, and which are often more highly 

 developed in the male than in the female. The male 

 alone of the tortoise utters a noise, and this only during 

 the season of love. Male alligators roar or bellow 

 during the same season. Every one knows how largely 

 birds use their vocal organs as a means of courtship ; 

 and some species likewise perform what may be called 

 instrumental music. 



In the class of Mammals, with which we are here 



27 



Dr. Scudder, "Notes on Stridulation," in 'Proc. Boston Soc. of 

 Nat. Hist.' vol. xi. April, 18G8. 



