50 plint's natueal HISTORY. [Book XI. 



of the blessings of. sight, distinguish life from death. Eyes, 

 however, have not been granted to all animals ; oysters have 

 none, but, with reference to some of the shell-fish, the question 

 is still doubtful ; for if we move the fingers before a scallop 

 half open, it will immediately close its shell, apparently from 

 seeing them, while the solen 88 will start away from an iron 

 instrument when placed near it. Among quadrupeds the 

 mole 89 has no sight, though it has something that bears a re- 

 semblance to eyes, if we remove the membrane that is ex- 

 tended in front of them. Among birds also, it is said that 

 a species of heron, which is known as the "leucus," 9 ^ is 

 wanting of one eye : a bird of most excellent augury, when 

 it flies towards the south or north, for it is said that it 

 portends thereby that there is about to be an end of perils and 

 alarms. Nigidius says also, that neither locusts nor grass- 

 hoppers have eyes. In snails, 91 the two small horns with which 

 they feel their way, perform the duties of eyes. Neither the 

 maw worm 93 nor any other kind of worm has eyes. 



CHAP. 53. — THE DIVERSITY OF THE COLOUR OF THE EYES. 



The eyes vary in colour in the human race only ; in all 

 other animals they are of one uniform colour peculiar to the 

 kind, though there are some horses that have eyes of an azure 

 colour. But in man the varieties and diversities are most 

 numerous ; the eyes being either large, of middling size, re- 

 markably small, or remarkably prominent. These last are 

 g-enerally supposed to be very weak, while those which are 

 deep-seated are considered the best, as is the case also with 

 those which in colour resemble the eyes of the goat. 



CHAP. 54.— THE THEORY OF SIGHT— PERSONS WHO CAN SEE BY 



NIGHT. 



In addition to this, there are some persons who can see to a 



f* Or razor-sheath. See B. x. c 88. _ . • 



89 Aristotle was of this opinion, hut Galen maintained that the mole can 



see Its eye is extremely small, and hard on the surface, 



so Or "white" heron. As Cuvier remarks, this is probably a mere 



"Tit is almost needless to remark, that both snails, as well as locusts and 

 grasshoppers, have eyes. 

 02 Lumbricus. 



