102 
E YES AXD SIGHT. 
the eyes, and also supply the tracheal vesicles, which 
are found between the ommatidia. 
We have seen that the compound eyes really con- 
sist of a number of separate eyes, united together and 
directed to different points (Fig. 44) of the horizon, 
and thus permit the insect to have a wider range of 
vision in all directions than would have been possible 
with a simple eye. 
The number of facets in the compound eyes of 
bees differs greatly, and in the worker the lowest is 
given as 3500, whereas we have ourselves found as 
many as 5000, and nearly as many in the queen. 
Drones, however, like all males which have to seek 
their females, have larger eyes, and the facets. Dr. 
Hicks (66) says, are larger and more numerous than 
those of either queen or worker. He also says that 
the hexagonal shape is assumed during the process of 
developement in consequence of their agglomeration, 
and points out as a proof that the external lenses, 
where not in contact with others, are round. 
The reader will naturally ask the question : If 
there are so many eyes, how is a single true image 
of surrounding objects produced by the compound 
eve of the bee ? 
J. Muller (114) was the first who gave an in- 
telligible explanation of the way insects see with 
their compound eyes. He regarded their eyes as a 
series of simple eyes, and that those rays of light 
which pass only through the crystalline cones, or are 
reflected from their sides, can reach the correspond- 
ingj nerve fibril. The others are absorbed bv the 
