THE RATTLE, 305 



once ; for what would cause such vestiges to harden into a 

 compHcated and symmetrical form ? 



To Dumeril we owe some of our best conceptions of the 

 growth of the rattle, which, whether it has or has not been 

 evolved from the mere horny spine that terminates the tails 

 of so many snakes, has certainly nozv an express provision for 

 its production. 



Like hair, claws, or nails, the rattle is horny matter excreted 

 and hardened. In his Elementary Lessons in Physiology, 

 Prof Huxley shows us how in the growth of a nail new 

 epidermic cells are added to the base, constraining it to move 

 forward. ' The nail, thus constantly receiving additions from 

 below and from behind, slides forward over its bed and 

 projects beyond the end of the finger.' If the reader will 

 look at his finger nail, and suppose the end bone of the 

 Crotalus spine to be the * bed' of the nail, he will to a certain 

 extent be able to comprehend how the rattle grows out ; but 

 that the links become detached in succession is a phenome- 

 non so astonishing and at the same time so difficult to 

 comprehend, that few naturalists have ventured to state 

 positively how this occurs. Conjecturally only and diffi- 

 dently do I, therefore, presume to offer a supposition ; and if 

 my readers will once more pardon reference to human nails, 

 and lend the aid of their imagination, they may be able to 

 evolve a true theory out of my crude idea. 



The young readers of Annt Judys Magazine were also, a 

 few years ago, ^ invited to lend the aid of their pink little 

 finger nails to the illustrative development of a supposed 



1 'The History of a Rattle,' by Catherine C. Hopley, Aunt Jtidy s Magazine, 

 July 1877. 



