Frogs, and their Contributions to Science. 125 



days than others, depending doubtless on the weather and 

 the state of the circulation. Some of the Hylee, a species 

 of frog inhabiting trees, possess an undoubted chameleon 

 faculty of assuming different shades of color quite perplex- 

 ing to those in search of them. 



The mouth of the frog is large. The tongue springing 

 from the lower jaw is long, bifid, and when at rest turned 

 back upon itself. A wide esophagus leads into a single 

 stomach capable of much distension. The small in- 

 testines are slightly convoluted and terminate in a kind 

 of pouch or cloaca, into which also empty the ureters and 

 ovarian and seminal ducts. The anus opens on the 

 back. The length of the alimentary canal is three or four 

 times that of the body. In the tadpole state it is nine or 

 ten. In man it is between five and six. The food of 

 frogs is insects and worms which are taken on the wing 

 or when crawling before them by a sudden darting out of 

 the tongue and sometimes with a leap. Like the lion, 

 styled the king of beasts, the frog preys on no dead car- 

 cass. There must be life or motion to tempt him to strike. 

 Like man also, styled the highest animal, he sometimes 

 preys upon his own species. In a jar, in which I once 

 kept some frogs, there was a rare specimen of a Hyla, a 

 dimunitive kind of tree frog which I one day missed. 

 Noticing an undue fullness of the stomach of one of his 

 larger companions I performed upon him the operation 

 of gastrotomy and delivered my Hyla, like a second Jonah, 

 a little the worse for the gastric juice of his devourer but 

 still living. 



The lymphatic and lacteal system of the frog is highly 

 developed. A pair of pulsating lymphatic hearts may be 

 easily detected, one on each side of the coccyx, while 

 another pair is found not so easily, under the posterior 

 edge of the scapulae. Their nervous system is also exceed- 

 ingly well developed. The peculiarity attending the 



