
BIRD’S-EYE VIEWS. 511 
deep semilunar groove in the roof ofthe bony orbit. But it 
_ does not belong to the eye at all, and seems to be stowed 
; there for want of room elsewhere. Its long duct runs along 
_ the top of the orbit into the nose, pouring out a secretion 
_ that lubricates the mucous membrane (pituitary membrane) 
-of the nasal passages. 
: The lachrymal glands keep the eye’s face clean, and relate 
_ chiefly, if not wholly, to the movements of the eyelid. The 
_ eyeball itself rolls about by the indirect aid of a different 
= tissue—the areolar, or cellular, as it is indifferently called,— 
_ the interstices of which are filled with fat. Ordinarily, the 
- Socket of an eye is much too large for the ball, and of a 
nical, instead of globular shape, so that the ball can no 
_ More fit or fill it, than can a marble dropped into a candle 
q extinguisher. A bird’s eyeball is more nearly fitted to its 
Socket than that of most mammals; still, it rests wholly or 
_ Ingreat part upon a bed of fat. This soft, yielding, elastic 
a substance gently presses the eye forwards, and holds it there 
7 = place, accurately adapted to the lids, while at the same 
time it allows the ball to rotate any way upon its own axis, 
tid also keeps it greased. We have'a great deal of fat in 
"r own eye-sockets in health. The reason that people’s eyes 
_ e sunken or “hollow” after a long illness, is because part 
of it is wasted away. While there is so much fat all around 
eyeball, there is not a particle in the eye itself; this 
hay ratively clumsy and stupid material would be like a 
tins in a china-shop in such a nervous quick-witted struc- 
Ducks are said to roll their eyes up in a thunder-storm, 
Very likely they do, since all birds move their eyes about 
€or less when they are not asleep. But the amount and 
Sree of ‘motion that a bird’s eye is capable of is small int 
~ iparison with that enjoyed by most mammals’ eyes. This 
“S partly from the shape of the orbit, and partly from 
Shape of the ball itself, which last is very singular, as 
"e shall see in the sequel. Nevertheless, there are as many 













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