302 NATURAL THEOLOGY. 



II. In birds, the compensation is still more 

 striking. They have no teeth at all. What have 

 they then to make up for this severe want ? I 

 speak of granivorous and herbivorous birds : such 

 as common fowls, turkeys, ducks, geese, pigeons, 

 «fcc. ; for it is concerning these alone that the 

 question need be asked. All these are furnished 

 with a peculiar and most powerful muscle, called 

 \\ie gizzard ; the inner coat of which is fitted up 

 wath rough plaits, which, by a strong friction 

 against one another, break and grind the hard ali- 

 ment as effectually, and by the same mechanical 

 action, as a coffee-mill would do. It has been 

 proved by the most correct experiments that the 

 gastric juice of these birds will not operate upon 

 the entire grain : not even when softened by water 

 or macerated in the crop. Therefore, without a 

 grinding machine within its body, without the tri- 

 turation of the gizzard, a chicken would have starv- 

 ed upon a heap of corn. Yet, why should a bill 

 and a gizzard go together? why should a gizzard 

 never b^ found where there are teeth ? 



Nor does the gizzard belong to birds as such. 



Where it is abundant, the configuration of the intestines which is 

 intended to delay its descent is less complex. Where the food is 

 more scarce, the intestine is longer, and the valvular obstruction 

 greater. This has been observed by Sir E, Home, in comparing 

 the cassowary of Java with the cassowary of New South Wales, 

 and the American ostrich wilh the same bird inhabiting the deserts 

 of Africa. The same comparison has been made between the 

 Leicestershire sheep and the mountain sheep of Scotland. 



