( clmat ) 
insect in direct connection with the eye, it being impossible 
that it can learn by individual experience, and in the 
highest degree improbable that deficiencies in the optical 
instrument can, in the insect, be remedied by mental opera- 
tions as they are in ourselves, and, if so, it becomes 
necessary to inquire whether the insect may not be able, by 
means of its eyes, to directly perceive certain important con- 
ditions of material objects that we only obtain a knowledge 
of by the aid of our mind. Or, to put it more correctly—as 
I believe—certain cerebral structures in connection with the 
Vertebrate sense of sight being not present in insects, other structures 
to compensate for their absence may be eapected to occur in more 
direct connection with the eye. If so, it becomes highly probable 
that the functions of the insect-eyes are not only dissimilar 
from ours, but are also more complex. If an insect is aware 
of the presence of objects when it is at rest, if it is able to 
guide itself during rapid movement by discriminating with 
delicacy rapidly occurring differences of lights and shades, to 
perceive the direction and rapidity of movement, and to dis- 
tinguish so much of the outline of objects as to give it an 
idea of extension in the three dimensions of space; if it 
has all these capacities, and perhaps others in addition, and 
if these are due to the eyes and not to the mind, then it 
certainly is highly probable that the direct functions of the 
optic organs may be not simple but complex; that whereas 
our vision is a very perfect development of one process, 
insect vision may be developments of two or three processes 
of perhaps different degrees of perfection? If this be the 
case, we have scarcely commenced to get any exact knowledge 
of the ways in which the world appears to insects. As an 
eye in its primitive form is an organ sensitive to light and 
shade, it is probable that perceptions of light and shade have 
become perfected in the insect’s eye; and, though these may 
not be integrated into any continuous picture, they may be 
excessively perfect, and it is not improbable that insects are 
largely guided in their movements by direct perceptions of 
lights and shades. There seems considerable reason for 
supposing that some insects, at any rate, take as the main 
guide to any particular series of movements the direction of 
greatest light; some species of insects now immolate them- 
PROC. ENT. SOC. LOND., V., 1888. I 
