THE STOMACH. 51 



reason is evident; for the animal matter on which they 

 feed requires no actual grinding to reduce it, the action 

 of the gastric juice being sufficient for the purpose of 

 dissolving it; whereas, without the powerful working of 

 this grinding-machine within its body, a fowl, for in- 

 stance, without a gizzard, would receive no sustenance 

 from the grains on which it depends chiefly for support, 

 since we have seen that until these grains are bruised 

 and crushed, the gastric juice will not act upon the 

 mealy or nourishing matter contained within the husk. 

 And there are reasons for supposing, that in this pro- 

 cess, nature acts according to certain wise laws, in most 

 cases suiting the quantity and quality of the gastric 

 juice to the necessities of the bird. One of our ablest 

 anatomists*, indeed, concluded that the stomach became 

 more and more fitted to economize the food, as the 

 country to which the bird belongs became less fertile, 

 or less able to provide the requisite supply. In some 

 cases, where the gizzard is imperfect, and is unfitted to 

 act the part of a grinder, the bird is led by instinct to 

 provide itself with a singular substitute. 



We have alluded to the strange matters found in the 

 stomach of the Ostrich which died in this country. 

 Now, the reason why these birds and some others, such 

 as the Emu and Cassowary, which move over the ground 

 by running instead of flying, swallow such strange hard 

 substances, is this: their digestive organs are, generally 

 speaking, weak; accordingly, their well-known propen- 

 sity for swallowing glass, iron, and other such substances, 

 is an instinctive remedy for this deficiency, which is 

 further assisted by their habits of running; this motion 

 producing such an increased shaking or rubbing together 

 between these hard substances which they swallow, and 

 their natural food, as to render the strong action of a 

 gizzard in a great degree useless. Those who take an 

 interest in poultry are aware that they are in the con- 

 stant habit of picking up small stones. Many persons 



* Sir E. Home. 



E 2 



