8 IIISIORY OF 



to all appearance, aie of the same species. Thus in the tame 

 swan, the windpipe makes but a straight passage into the lungs ; 

 while in the wild swan, which to all external appearance seems 

 the same animal, the windpipe pierces through the breast-bone, 

 and there has several turnings before it comes out again, and 

 goes to enter the lungs. It is not to form the voice that these 

 turnings are found, since the fowls that are without them are 

 vocal ; and those, particularly the bird just now mentioned, that 

 have them, are silent. Whence, therefore, some birds derive 

 that loud and various modulation in their warblings, is not easily 

 to be accounted for ; at least the knife of the anatomist goes but 

 a short way in the investigation. All we are certain of is, that 

 birds have much louder voices, in respect to their bulk, than ani- 

 mals of any other kind ; for the bellowing of an ox is not louder 

 than the scream of a peacock. 



In these particulars, birds pretty much resemble each other 

 in their internal conformation ; but there are some varieties 

 which we should more attentively observe. All birds have, pro- 

 perly speaking, but one stomach ; but this is very different 

 in different kinds. In all the rapacious kinds that live 

 upon animal food, as well as in some of the fish-feeding tribe, 

 the stomach is peculiarly formed. The oesophagus, or gullet, in 

 them, is found replete with glandulous bodies, which serve to 

 dilate and macerate the food, as it passes into the stomach, which 

 is always very large in proportion to the size of the bird, and 

 generally wrapped round with fat, in order to increase its v/armth 

 and powers of digestion. 



Granivorous birds, or such as live upon fruits, corn, and other 

 vegetables, have their intestines differently formed from those 

 of the rapacious kind. Their gullet dilates just above the breast 

 bone, and forms itself into a pouch or bag, called the crop. 

 This is replete with salivary glands, which serve to moisten and 

 soften the grain and other food which it contains. These glands 

 are very numerous, with longitudinal openings, which emit a 

 whitish and a viscous substance. After the dry food of the bird 

 lias been macerated for a convenient time, it then passes into 

 the belly, where, instead of a soft moist stomach, as in the ra- 

 pacious kinds, it is ground between two pair of muscles, common- 

 ly called the gizzard, covered on the inside with a stony ridgy 

 coat, and almost cartilaginous. These coats rubbing against 



