48 THE STORY OF BIRD-LIFE. 



fleshy tongue, that might be well compared to 

 our own. 



But this chapter is to record how a bird feeds 

 and digests its food. We have seen now, I think, 

 fairly clearly, how important a place the beak 

 and tongue fill in the matter of obtaining the 

 food, and how these have been slowly modified 

 so as to assume strange forms, in response to the 

 need of obtaining food otherwise inaccessible. 

 But some may ask, what is the evidence that 

 these changes have taken place ? This would 

 take too long to discuss. But we have very 

 good witnesses in the birds themselves : one can 

 see that a long straight bill can become a 

 long upturned one, or a long spoon-shaped one, 

 for the change is enacted before our eyes in 

 every avocet and every spoon-bill, and every 

 cross-bill and every wry-bill-sand-piper and every 

 humming-bird, and so on, that is born. In 

 none of these birds are the bills of these peculiar 

 shapes at birth. They assume these various 

 forms later on in life ; all begin with just ordinary 

 beaks. 



Just as the beak becomes changed from one 

 form to another to enable it to do ^vork of a 

 certain kind more efficiently, so the stomach 

 and intestines become also changed. The one 

 must work in sympathy with the other, accord- 

 ing to the need in each particular case. 



The form and structure of the intestine or 

 -alimentary canal generally, hov>^ever, do not 

 "Vary as the beak, but rather as the need for 

 ^^daptation to a new food. Thus the form of 

 tihe digestive organs of the spoon-bill, the avoset, 



