Introduction 



largely on bullfrogs; leopard frogs have been found in the stomach 

 of a loon;^ bronzed grackles have been observed eating wood 

 frogs, ^ and so on. 



The poison secreted in the skin of theSalientia concerns only 

 the enemies who feed upon them; it does not aflfect man. The 

 secretion, even if rubbed on the hands, cannot cause the forma- 

 tion of warts; however, it will produce an irritation and smarting 

 if transferred from the hands into the mouth or eyes. It is said 

 that German violinists purposely handle toads before playing, 

 and that the secretion prevents the hands from perspiring greatly.' 



VIII. Regeneration of Lost Paris in the Salientia 



In the Urodela the power to regenerate lost parts is very 

 great. Not only the gills and the tail of a salamander, but the 

 limbs also, will be reproduced perfectly if bitten off by some hungry 

 beetle or fish, or torn off by one of its own kin. 



This power of regeneration extends also to the more special- 

 ized group, the Salientia, but the reproduction of the lost part 

 is the more perfect, the younger the specimen. The tadpole's 

 tail may be bitten off or injured again and again, and each time 

 it will grow to its previous size.^ This is true even at the 

 time when the period for the resorption of the tail has almost 

 been reached. 



If the hind limb of a metamorphosing tadpole be injured, 

 even amputated, above the knee, before the completion of the 

 metamorphosis, it will be regenerated completely. After the 

 frog form is attained, the power of regeneration is largely lost, 

 although the injured limb will always show some tendency 

 toward replacing the lost portion. 



IX. Voice among the North American Salientia 



All members of the North American Salientia can produce 

 sound. This sound is caused by air passing over vocal cords 

 in the larynx of the throat, and so it constitutes a true voice. 

 The loud croaking given during the breeding season is produced 



1 Hills (T. M.), Zoological Society Bulletin, N. Y. Zool. See., April, 1904. 



2 Miller (W. Da W.), Plamfield, N. J., Bird Lore. 



3 Boulenger. 



* For the relation of this regeneration to the notochord, see Bryn Mawr College Monographs, 

 1902. Morgan (T. li.) and Davis (S. E.). 



