MANUAL OK THE APIARY. 



73 



these vibrations, as we recognize pitch, or whether they iust 

 distinguish the tremor, I think no one knows. There is some 

 reason to believe that their delicate touch-organs may enable 

 them to discriminate between vibrations, even more accurately 

 than can we by the use of our ears. A slight jar will quickly 

 awaken a colony of hybrids, while a loud noise will pass un- 

 noticed. If insects can appreciate with great delicacy the 

 different vibratory conditions of the air by an excessive devel- 

 opment of the sense of touch, then undoubtedly the antenns 

 may.be great aids. Dr. Clemens thought that insects could 



Fig. 20. 



Fig. 21. 



Facets of Compound 

 Eyes, 



after Dujardin. 



F Facets. 

 S Hairs. 



Section of Compound Eye, after Oagenlxmer. 



c Cornea. 

 R Rods. 



C Cells. 

 Nerve. 



only detect atmospheric vibrations. So, too, thought Linnaeus 

 and Bonnet. Mayer has proved that the hairs on the antennae 

 of mosquitoes vibrate to different sounds. From our present 

 knowledge, this view seems the most reasonable one, for noth- 

 ing answering in the least to ears, structurally, has yet been 

 discovered. 



The eyes are of two kinds, the compound, which are 

 always present in mature insects, and the ocelli or simple 

 eyes, which may or may not be present. When present there 

 are usually three of these ocelU (Fig. 3), which, if joined by 

 lines, will describe a triangle, in the vertices of whose angles 



