S2 A HISTORY OF 



into certain receptacles like bladders, running along the length of the 

 whole body. Nor are these openings obscure, or difficult t? be dis- 

 cerned ; foi a probe, thrust into the lungs of a fowl, will easily find a 

 passage into the belly ; and air blown into the wind-pipe will he seen 

 to distend the animal's body like a bladder. In quadrupeds .his pas- 

 sage is stopped by the midriff; but in fowls the communication is ob- 

 vious ; and consequently they have a much greater facility of taking a 

 long and large inspiration. It is sometimes also seen that the wind- 

 pipe makes many convolutions within the body of the bird, and it is 

 then called tne labyrinth ; but of what use these convolutions are, or 

 why the wind-pipe should make so many turnings within the body of 

 some birds, is a difficulty for which no naturalist has been able to ac 

 count. 



This difference of the wind-pipe often obtains in animals that, to 

 all appearance, are of the same species. Thus in the tame swan, the 

 wind-pipe makes but a straight passage into the lungs ; while in the 

 wild swan, which, to all external appearance, seems the same animal, 

 the wind-pipe 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 anatomists 

 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, properly speaking, but one 

 stomach ; but this is very different in different kinds. In all the ra- 

 pacious 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 warmth and powers 

 of digestion. 



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

 getables, have their intestines differently formed from those of the ra- 

 pacious 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, wl.,ch serve to moisten and soften the grain and other 

 food which it contains. These glands are very numerous, with longi- 

 tudinal openings, which emit a whitish and a viscous substance. Af 

 tcr the dry food of the bird has been macerated for a convenient time, 

 it then passes into the belly, where, instead of a soft, moist stomach, 

 ns in the rapacious kind, it is ground between two pair of muscles, 

 commonly called the gizzard, covered on the one side with a stony, 

 ridgy coat, and almost cartilaginous. These coats rubbin 



