WADING BIRDS. 83 



lies ; and though their feet, and also their necks, heads, and 

 bills, vary much with the kind of place in which the food is 

 found, and the way in which it has to be taken from that 

 place, there is in all cases a corresponding variation of the 

 two ; so that when the feeding-place and food of the bird are 

 known, it is always apparent that the feet, as the immediate 

 means of conveyance to the food and of support while it is 

 taken, and the neck, head, and bill, as the immediate organs 

 of capture, are so well adapted for acting in concert, that if 

 the one were changed without a corresponding change in the 

 other, the bird would be far less efficient than it is. The 

 principal food of the whole order consists of animal sub- 

 stances, so that they have membranous stomachs and not 

 gizzards, though some have a slight approach to that cha- 

 racter. These last occasionally eat vegetables when in a state 

 of nature, might be wholly or chiefly fed on them in confine- 

 ment, and would no doubt, in that case, partake more of the 

 gizzard structure. In all birds, indeed, the texture of the 

 stomach can accommodate itself less or more to the nature 

 of their food ; so that when the food requires grinding, an 

 operation which only the grain-eating birds can perform, and 

 that, too, in a very imperfect manner, the stomach becomes 

 in time a grinding apparatus.* Even in its most perfect 

 gizzard form, however, it becomes only half the mill the 

 nether millstone, as it were ; and hence the necessity that 

 the gallinse are under of picking up gravel to assist the 

 gizzard in the attrition of their food. The necessity and 

 efficiency of these substances in the process of digestion are 

 proved by the fact, that the birds, when they can pick up 



* If the author means to say that in process of time the organic 

 structure of the stomach will become changed, we cannot assent to his 

 proposition. It is always adapted for the food upon which the bird is 

 destined to live, and to change that food would be to destroy the bird by 

 starvation, for the stomach would never change. M. 



G2 



