THE STOMACH. 51 



the finger, the muscles will feel to the touch as hard as 

 stones; when they relax, the grain, upon which they were 

 then working, passes on, and a further supply, as in the case 

 of the mill, passes under these natural rollers. These alter- 

 nate actions succeed each other slowly but regularly ; and on 

 placing the bird close to the ear, as the food and stones roll 

 under the pressure of the muscles of the gizzard, a sound not 

 unlike the noise of the tide rolling upon a shingly shore^ 

 may be distinctly heard at intervals, as if the waves were 

 ebbing and flowing; and during all this process, the gastric 

 juice slowly flows in from the lower part of the gullet or 

 second stomach, and mingles intimately with the digesting 

 food. 



We have stated that the fowl best calculated for this exa- 

 mination should be a full-grown young one; but although, 

 in this almost immature state, the gizzard is fully developed, 

 if we were to dissect a chick, we should find not a vestige of 

 a gizzard, but merely a thin pellicle or skin. And it is for 

 this reason, that whereas the young fowl is nevertheless old 

 enough to live entirely on grain, and therefore requires the 

 assistance of a gizzard, the little chick, on emerging from its 

 shell, for a short time lives on soft food, and requires no such 

 aid. As it advances in age, however, the pellicle gradually 

 thickens, till at last, by pressure and rubbing, it becomes a 

 hard and grinding membrane. 



From the different construction and digestive powers of 

 the stomachs of birds, it must be evident that some are able 

 to continue a much longer time without food than others. 

 An Eagle has been known to fast for three weeks ; those who 

 had the charge of it having forgotten to provide its usual 

 supply of food. It soon, however, recovered its strength, 

 and did not appear to suffer from its extraordinary abstinence. 

 How long other birds can sustain hunger, we can have few 

 opportunities of learning, but probably it will be found that 

 such as are most likely, from their habits and particular sort 

 of food, to be more exposed to a precarious and doubtful 

 supply, are, generally speaking, best provided against the 

 chance of suffering. But this is not always the case, for 



