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 Libellulidse 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, Paukrath, Exner, and Yiallanes practically established the fact 
that while insects are shortsighted and perceive stationary objects 
Fig. 10.— Sensory organs in insects: A, one element of eye of cockroach (after Grenadier); B, 
diagrammatic section of compound 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 ; e, small pit on 
terminal joint of palpus in Perla (after Packard) ; E, diagram of sensory ear of insect (after Miall & 
Denny); F, auditory apparatus of Meconema; a, fore tibia of this locust; b, diagrammatic section 
through same (after Graber) ; £?, auditory apparatus of Caloptenus, seen from inner side, sbowing 
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 seusations of color are different 
from those produced 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 clearly that they have this sense of color 
