34 



that their function is of a low order, and lends weight to the view that 

 they are useful chiefly for near vision and in dark places. The com- 

 pound eyes are prominent and adjustable in proportion as they are of 

 service to the species, as witness those of the common house-fly and of 

 the Libellulidai or dragon-flies. It is obvious from the structure of 

 these compound eyes that impressions through them must be very dif- 

 ferent from those received through our own, and, in point of fact, the 

 late experimental researches of Hickson, Plateau, Tocke and Lemmer 

 mann, Pankrath, Exner, and Yiallanes practically established the fact 

 that while insects are shortsighted and perceive stationary objects 



Fig. 10.— Sensory organs in insects: A. oue element of eye of cockroach (after Grenachep) ; B, 

 diagrammatic section of compojind eye in insect (after Miall & Denny) ; C, organs of smell in Melo- 

 lontha (after Kraepelin) ; D, a, b. sense organs of abdominal appendages of Chrysopila ; c, small pit on 

 terminal joint of palpus in Perla (after Packard) ; E, diagram of sensory ear of insect (after Miall & 

 Denny); J'', auditory apparatus of Meconema; a, fore tibia of this locust; 6, diagrammatic section 

 through same (after Graber) ; G, auditory apparatus of Calopteniis, seen from inner side, showing 

 tympanum, auditory nerve, terminal ganglion, stigma, and opening and closing muscle of same, as 

 well as muscle of tympanum membrane (after Graber). — All very greatly enlarged. 



imperfectly, yet their compound eyes are better fitted than the verte- 

 brate eye for apprehending objects set in relief or in motion, and are 

 likewise keenly sensitive to color. 



So far as experiments have gone they show that insects have a keen 

 color sense, though here again their sensations of color are different 

 from those i)rodiiced upon us. Thus, as Lubbock has shown, ants are 

 very sensitive to the ultra violet rays of the spectrum, which we can 

 not perceive, though he was led to conclude that to the ant the gen- 

 eral aspect of nature is presented in an aspect very different from 

 that in which it appears to us. In reference to bees, the experiments 

 of the same author prove clearlj^ that they have this sense of color 



