itiuns. 7 



to fit them for tlie waters ; iti others they are separate, for the 

 better holding objects, or clinging to trees for safety. Such as 

 have long legs have also long necks, as otherwise they would 

 be incapable of gathering up their food either by land or water. 

 But it does not hold, however, that those who have long necks 

 ehotild have long legs, since we see that swans and geese, whose 

 necks are extremely long, have very short legs, and these chiefly 

 employed in swimming. 



Thus every external part, hitherto noticed, appears adapted 

 to the life and situation of the animal ; nor are the inward parts, 

 though less immediately appropriated to Hight, less necessary to 

 safety. The bones of every part of the body are extremely 

 light and thin ; and all the muscles, except that immediately 

 moving the wings, extremely slight and feeble. The tail, which 

 is composed of quill feathers, serves to counterbalance the head 

 and neck ; it guides the animal's flight like a rudder, and greatly 

 assists it either in its ascent or when descending. 



If we go on to examine birds internally, we shall find the same 

 wonderful conformation fitting them for a life in air, and increas- 

 ing the surface by diminishing the solidity. In the first place, 

 their lungs, which are commonly called the sole, stick fast to 

 the sides of the ribs and back, and can be very little dilated or 

 contracted. But to make up for this, which might impede tlieir 

 breathing, the ends of the branches of the windpipe open into 

 them, while these have openings into the cavity of the belly, atid 

 convey the aii- drawn in by breathing into certain receptacles like 

 bladders, running along the length of the whole body. Nor are 

 these openings obscure, or diflicult to be discerned ; for a probe 

 thrust into the lungs of a fowl will easily find a passage into 

 the belly ; and air blown into the windpipe will be seen to dis- 

 tend the animal's body like a bladder. In quadrupeds this pas- 

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

 is obvious ; and consequently, they have a much greater facility 

 of taking a long and large inspiration. It is sometimes also 

 seen that the windpipe makes many convolutions within the 

 body of a bird, and it is then called the labyrinth ,- but of what 

 use these convolutions are, or why the windpipe should make 

 so many turnings within the body of some birds, is a difficulty 

 for which no naturalist has been able to account. 



This diiference of the windpii)c often obtains in animals that. 



