INSECTA : HYMENOPTERA 413 



form a reversed image on the retina, as in our own eyes, and 

 if both sets of eyes are in use at once confusion is suggested. 

 However, it may be that these ocelli are only used for objects 

 very close to the eye, whilst the compound eyes alone are 

 used when looking at objects farther off. 



Undoubtedly ants are very sensitive to light, specially 

 disliking blue and violet light, as has been shown by Lord 

 Avebury's experiments, in which he covered a formicarium 

 with strips of different coloured glass, and found that the ants 

 always removed themselves and the brood from under violet 

 glass, and took up their position by preference under red 

 glass, though some were also to be found under the green 

 and yellow strips. They would, however, collect under the 

 violet glass rather than be exposed to full light under plain 

 glass. Lord Avebury from his experiments also came to the 

 very interesting conclusion that ants are very sensitive to the 

 shorter waves of light which extend beyond the blue end of 

 the spectrum, and he suggests that they may, therefore, 

 perceive a colour which is unknown to us, which would make 

 their view of things very different from ours. 



Ants seem to be quite oblivious to sounds 

 (^Hearing w i tn ^ n our ran ge of hearing, though in many 

 ants, Lasius flaws amongst them, a certain peculiar 

 organ has been described l on the first segment of the gaster, 

 which is thought to be an instrument for producing a sound 

 of very high pitch. It consists of a number of fine parallel 

 ridges running across the first gastric segment, which, when 

 scraped upon by the overlapping edge of the segment in 

 front, produces a sound so high in pitch that it is in most 

 cases inaudible to the human ear, but which is probably 

 audible to ants. The existence of special auditory organs to 

 respond to this sound is not yet fully demonstrated, though 

 certain structures (" chordo- tonal " organs) in the tibia of each 

 leg may be auditory in function. 



The sense of touch is highly developed and 

 * s * g reat importance to ants. Sensitive hairs 

 are specially developed on the antennae, the chief 

 tactile organs with which the ant feels object after object 

 as she moves forward, and with which she appears to 

 communicate with her fellows. That they do thus com- 

 1 Lubbock, Ants, Bees, and Wasps, p. 230. 



