Organs of Nutrition 127 
a forward or backward direction. Along the sides of the 
tongue are two series of fleshy teeth, in shape exactly 
like the poison-fangs of a rattlesnake. 
Mention must be made of the unique and greatly 
specialized tongues of Hummingbirds and Honey Creepers. 
The outer edges of this organ are curled into two tubes, 
Fig. 100.—Side view of Flamingo’s tongue, forcibly lifted above mandible, show- 
ing fleshy recurved teeth. 
which are more or less split and frayed near the tip, 
forming delicate brushes—efficient instruments either to 
suck up nectar or to flick out insects from the heart of 
corollas. 
The Crop 
From the back of the throat to the stomach extends 
a tube, the gullet or cesophagus, through which the food 
