VISION IN INSECTS. , 119 



to light was so great, that when we shut up a few of 

 them, with their pupae, under a glass, with only a 

 sprinkling of earth, they contrived to pile up enough 

 to cover themselves completely in ; and even when we 

 made the floor of their prison of a plate of glass, so 

 that the light could be admitted below, they still con- 

 trived to manage their scanty materials so as to pave 

 this glass floor, sprinkling it with minute grains. 

 Two females, with a few workers that chanced to 

 escape, were afterwards discovered on the floor, within 

 a bramble leaf, -which had coiled up in withering, and, 

 in deficiency of other material to stop up the open- 

 ings, they had gnawed portions of the leaf itself, and 

 masoned them into little walls to exclude the light, 

 But, so far from inferring from this that they are blind, 

 we should be disposed to conclude that they have eyes 

 extremely sensible to light , though, from their mi- 

 nuteness, they elude our search. It is to be recol- 

 lected, indeed, that the insect is one of the smallest, 

 being rather less than a sixth of an inch in length ; 

 but the circumstance is more remarkable from most 

 ants having very large and prominent eyes*. 



A more extraordinary opinion has been maintained 

 respecting the blindness of spiders, inasmuch as their 

 eyes are, in most species, so very conspicuous, and 

 more brilliant than in any animal we at present re- 

 collect. Speaking of one of the hunting spiders 

 (Salticus scenicus ?), Swammerdam says, " These 

 seize their prey by a sudden leap, and therefore na- 

 ture has provided them, as well as other spiders, 

 with eight eyes, and a most acute sight. It is more 

 difficult to judge of this sight in spiders that make 

 webs, for, so far from taking any notice of a finger 

 put close to their eyes, they neither express any con- 

 cern at it, nor attempt to run away ; whereas, let the 

 most minute animal fall into their nets, they imme- 



