278 



KTDD'S OWN JOURNAL. 



There is another singularity in this mysterious 

 liquid, namely, the different force with, which it 

 acts on the various substances used for food by 

 different birds. Thus the gastric juice in the 

 stomach of those birds which live on flesh, acts 

 very sparingly on vegetable substances. On 

 examining the castings or pellets of some Eagles, 

 which have been occasionally fed with dead 

 Pigeons, it was found that the vegetable food, 

 peas, wheat, and barley, which had been swal- 

 lowed by these birds of prey, enclosed within the 

 crops of the Pigeons, remained entire, being qnly 

 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 pro- 

 duced 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 grinding 

 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 materially in different birds; 

 but, generally speaking, the action of this 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 muscular globes or 

 gizzards of the grain-devouring 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 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 mealy or nourishing matter contained within 

 the husk. And there are reasons for supposing, 

 that in this process 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 anato- 

 mists (Sir E. Home), indeed, concluded that the 

 stomach became more and more fitted to economise 

 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. 



* Zoological Journal, vol. x., p. 18G. 



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 

 propensity for swallowing glass, iron, and other 

 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 constant habit of picking up small 

 stones. Many persons consider this as an 

 accidental occurrence, but it is by no means so ; 

 they do it, like the Ostrich, for the purpose of 

 assisting the powers of the gizzard in grinding 

 the shells and outer coats of the grains, so as to 

 render them fit for final digestion. In the 

 stomach of a Turkey-hen, nearly one hundred 

 stones have been counted; and in that of a Goose, 

 a still larger number; but these are nothing to 

 the extraordinary contents of a common fowl's 

 stomach, in which were found three pieces of flint, 

 three metal buttons, fourteen nails, several of 

 which were very sharp, in addition to a great 

 number of small stones.* The coat of the bird's 

 stomach, with the exception of some slight 

 scratches on the inner membrane, was in its 

 natural state ; probably, however, if the gizzard 

 had been closely examined, it would have been 

 found diseased or defective in its operations, thus 

 inducing the fowl to make up its deficiency by so 

 unnatural an addition. Sir James Ross, in his in- 

 teresting " Voyage of Discovery towards the South 

 Pole," mentions having found in the stomach of 

 one of the " Great Penguin " (Apterodytes 

 ForsteriJ, the frequenters of high southern lati- 

 tudes, from two to ten pounds weight of pebbles, 

 consisting of granite, quartz, and trappean rocks, 

 swallowed, no doubt, to assist them in digesting 

 the various species of crustaceous animals on 

 which they feed. 



But the best way of understanding its curious 

 mode of working, will be, to follow the progress 

 of a meal swallowed by a fowl, between whose - 

 stomach and that of a corn-mill naturalists have 

 traced a very close resemblance. The grain is 

 first passed by the gullet into the craw, which may 

 be compared to the hopper of the mill, through 

 which the grain is gradually emptied on the 

 grinding-stones. There, as we have seen, it 

 remains a certain time, till it is considerably 

 softened ; and then, not all at once, but in very 

 small quantities, in proportion to the progress of 

 trituration, just as the hopper allows the grain to 

 dribble into the central hole in the upper mill- 

 stone, does it pass onwards to the gizzard, where 

 it is thoroughly bruised and reduced. Many ex- 

 periments have been made to ascertain the precise 

 manner in which the gizzard acts; but we are 

 still much in the dark respecting it. We may 



* Edinburgh Philosophical Journal, No. 411., 

 p. 206. 



