118 



Chapter V. 



VISION IN INSECTS. 



There is no animal naturally blind, says Bidloo*. 

 But the universality of the position is rendered doubt- 

 ful by the structure, if not by the actions, of some 

 insects observed by distinguished naturahsts, whose 

 testimony is unimpeachable. Latreille, for example, 

 describes two species of ants, whose workers are, to 

 all appearance, blind, though their males and females 

 have eyes sufficiently obvious. One from South Ame- 

 rica {Formica ccecd), in Olivier's collection, he had 

 never seen alive ; the other {Ponera contracta, Latr.) 

 he found under stones near Paris, though not com- 

 mon. " I have never," he says, " been able to detect 

 the eyes, even with the aid of a lens half a line in 

 focus. I have seen a great number of individuals, 

 both living and dead, and I have only once or twice 

 imagined I could just see a very small depressed point 

 in the place of the eyef." Again, he says, "if the 

 eyes exist at all, they can be of httle more use to 

 these ants than those with which nature has furnished 

 the mole ; for, like it, they are destined to pass their 

 days in obscure retreats, inaccessible to light, and are 

 never seen running about like the others in open day, 

 and if they do venture abroad from their dark galle- 

 ries, it is only during the nighty." 



We have ourselves verified all these observations 

 upon this species, at Havre de Grace, where it is more 

 common than at Paris. We found that their dislike 



* De Oculis et Visu. 

 t Hist, Nat, des Fourmis, 196, \ Ibid. 



