48 THE STOMACH. 



ally fed with dead Pigeons, it was found that the vegetable 

 food, peas, wheat, and barley, which had been swallowed by 

 these birds of prey, enclosed within the crops of the Pigeons, 

 remained entire, being only somewhat enlarged by heat and 

 moisture ; though the fleshy substances, even to the very 

 bones, were entirely consumed.^ 



Again, it has been observed, that this juice will not act 

 upon the grain swallowed by poultry and other granivorous 

 birds while it remains whole and entire. 



This fact has been further proved by actual experiment. 

 Some gastric juice was poured into a cup containing some 

 whole seeds, but it produced no effect upon them till they 

 were crushed. Hence it has been found, that if oats and 

 barley given to horses are previously killed by heating, and 

 crushed, the animal only requires half the quantity, and yet 

 thrives equally well. 



In considering the real stomach or gizzard, by which name 

 it will be more familiarly known, we shall find additional 

 cause for admiration in the mode by which Providence, with 

 reference to the food introduced, so nicely balances the grind- 

 ing powers of the gizzard with the dissolving or melting 

 powers of the gastric juice. This third or real stomach 

 differs, like the gullet, crop, and second stomach, very mate- 

 rially in different birds ; but, generally speaking, the action 

 of the gizzard may be compared to that of a coffee-mill, 

 grinding down the various substances introduced into a 

 pulpy matter. In those which feed on flesh and insects, 

 substances of no very hard texture, this stomach appears as 

 a thin membranous bag in comparison with the thick mus- 

 cular globes or gizzards of the grahudevouring class ; and the 

 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 instance, without a 

 gizzard, would receive no sustenance from the grains on 



* Zoological Journal, vol. x., p. 186. 



