152 FACULTIES OF BIRDS. 



conceive a bone to be composed like wood, or, taking 

 a more familiar instance, like an onion, of a great 

 number of strata. The strata of the onion are of 

 considerable thickness, but we must imagine that in 

 bone they are exceedingly thin. The gastric fluid of 

 owls or other animals will first dissolve the upper 

 stratum, but while it is doing this it will penetrate and 

 soften the contiguous strata, without dissolving them. 

 Hence the tenderness of bone that has lain in the 

 stomachs of animals. On the contrary, we must 

 suppose that the gastric liquor of the falcon has no 

 power of penetrating the internal strata, but that its 

 action is limited to the surface. According to this 

 supposition the bone will be digested without having 

 the internal parts softened ; and thus stratum after 

 stratum will be taken away, just as it would happen 

 if we had a menstruum capable of dissolving only 

 the superficial layer of an onion without acting upon 

 the others*.'' 



According to Sir Everard Home, the carrrion 

 crow (Corvus Corone) has the cavity of the gizzard of 

 an oval form, with a thick wrinkled lining and a weak 

 digastric muscle. From living chiefly upon carrion, 

 its sagacity appears to be rendered acute in discovering 

 not only a dead carcass, but animals which are weak 

 and sickly. When a crow therefore is seen lingering 

 about alone in any unusual place, it may be suspected 

 that a sheep or other animal is somewhere near, and 

 likely to die. When the animal becomes worse, the 

 crow approaches nearer, and as soon as it is unable 

 to move, pecks out its eyes, and sheep are often found 

 still alive with their eyes thus pecked outf. " The 

 crow," says Colonel Montagu, " will also pursue birds 

 on the wing, when pressed by hunger. We once saw 

 this bird in pursuit of a pigeon, at which it made 

 several pounces like a hawk ; but the pigeon escaped 

 * Dissertations, i. 162. t Comp. Anat. i. 275. 



