192 
EXPRESSION IN THE ANIMAL EYE. 
The wonderful compound eyes of insects recently 
formed the subject of a paper read by Lord Rayleigh 
before the Royal Society, recording observations of 
minute accuracy and ingenious measurement by Mr. 
A. Mallock. The general conclusions formed as to 
the actual power of these complex organs rather 
raises than lessens the claim to efficiency of the 
simpler vertebrate eye. The compound eye pieces 
together the separate impressions of the object seen, 
and should any of the facets be out of order, a blank 
must be left in the corresponding part of the picture. 
The only advantage which is claimed for insect-sight 
is that at the shortest distances the object seen is 
still in focus, which partly accounts for the “ short- 
sighted ” manner in which most insects seem to 
examine any object in which they are particularly 
interested. Seen under a powerful microscope, and 
measured by the delicate instruments so skilfully 
employed by Mr. Mallock, these insect eyes are 
marvels of geometrical symmetry. But they are 
merely organs of sight, not of expression. They are 
