50 THE STOMACH. 



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 interesting voyage of discovery towards the South Pole, 

 mentions having found in the stomach of one of the " Great 

 Penguin " (Apterodytes Forsteri), the frequenters of high 

 southern latitudes, 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 crusta- 

 ceous animals on which they feed. 



But the best way of understanding its curious mode of work- 

 ing will be to follow the progress of a meal swallowed by a 

 fowl, between whose stomach and that of a corn-mill natural- 

 ists 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 pro- 

 portion 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 experiments 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 learn, however, a good deal by examining a very lean 

 young fowl, when, on removing the feathers from the side of 

 the belly nearest the gizzard, its motion can be both felt, seen, 

 and heard. On pressing with the finger, the muscles will feel 

 to the touch as hard as stones ; when they relax, the grain, 

 * Edinburgh Philosophical Journal, No. iii. p. 206. 



