NATURAL SELECTION 



of the rattlesnake's rattle. The existence of 

 this appendage has long been a puzzle to phi- 

 losophical naturalists, and Darwinians have been 

 repeatedly challenged to account for the forma- 

 tion or preservation by natural selection of an 

 organ assumed to be injurious to the species. 

 The difficulty has lain in the assumption, too 

 hastily made, that the noise or the rattle must 

 be prejudicial to the snake by forewarning its 

 enemies or prey of its presence, and thus giving 

 the enemies time for sudden attack, and allow- 

 ing the prey to escape. On the theory of nat- 

 ural selection, the preservation of the species 

 must entail the atrophy of such an organ, or, 

 rather, must prevent its origination, unless the 

 damage occasioned by it be more than com- 

 pensated by some utility not hitherto detected. 

 Professor Shaler's hypothesis, however, sug- 

 gests the possibility that this whole speculation 

 is fundamentally erroneous. Far from being 

 injurious to the snake, by serving to warn its 

 prey, it would appear that the rattle may be 

 directly useful by serving as a decoy. Professor 

 Shaler has observed that the peculiar sound of 

 the rattle is a very close imitation of the note 

 emitted by a certain cicada common in Amer- 

 ican forests frequented by rattlesnakes ; and ac- 

 cording to his ingenious suggestion, the bird, 

 hearing the note and thinking to make a meal 

 of the cicada, advances upon its own destruc- 

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