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oontirms the fact that a pickerel will not bite at a motionless spoon-hook. The 

 retina of these fish has simply a thickening or area at the axis of vision. 



A somewhat similar experiment can be tried with the frog or toad. If one 

 attaches a bit of red Hanuel, a green leaf or any other small object to a thread 

 and dangles it before a frog he will quickly jump for it. A toad may be fed on 

 meat in a similar way, but in no case will the meat be taken unless it is in mo- 

 tion. Neither do these animals show any marked power of discrimination by 

 sight. They will jump at any small moving object and are apparently not able 

 to distinguish, till they have it in their mouths, whether it is an article of food 

 or a pebble. Investigations again show the presence of an area and absence of 

 a fovea. 



In some of the reptiles, however, a marked diflf'erence in power of discrimi- 

 nation by sight is noticed. Experiments were made wholly on a small lizard 

 ( horned toad ). If a dead Hy were put before him when he was hungry he 

 would eye it closely for a brief time then ([uickly take it. His aim was also cer- 

 tain, never missing his mark, while that of the ordinary toad was more at random, 

 throwing out her tongue indiscriminately at moving objects. It is true the lizard 

 was attracted more by a live and moving fly than by a dead, motionless one, but 

 he also had the power of perceiving things at rest. This little creature pos- 

 sessed a sharp and well defined fovea. 



In general, bird's eyes are almost as perfect as man's, and, likewise, the optic 

 lobes are even greater in proportion to the size of the body than that of man. It 

 is true that the bird often catches Hies as they buzz about, but it also inspects 

 each leaf carefully above and below for a worm or bug which may be there in 

 hiding and which it seldom fails to recognize. The hawk as it soars high in the 

 heavens sees the snake, rat or mouse in the grass and is frequently seen to dart 

 and secure its prey. Very acute sight is present in all birds and especially in 

 birds of prey. 



A great difference exists in the power of sight in mammals. The primates 

 possess the power of most acute vision. Many of the mammals depend on smell 

 and hearing more than on sight. The dog picks his master out of the crowd by 

 smell, so does the sheep her lamb. Sight in this case being only partial recogni- 

 tion and they are not sure until they have confirmed their sight by the sense of 

 smell. The same is true of the cow. for she must smell of the strange cow when 

 introduced into the herd. The horse is cured of his fright by smelling of the ob- 

 ject which caused it. In all these cases we find a motion of the ears showing that 

 the animal is not only using sight and smell but also hearing. Mammals in gen- 

 eral do not recognize a man by sight if he remains (juiet, but the crow easily sees 

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