ON THE ANTENNA AND HEAKING OF INSECTS. 61 



as the strings of an iEolian harp vibrate and emit various sounds 

 according as they are differently struck by the air. In this view, 

 however, we might infer that nature would have made antennae in the 

 form of rods, consisting of a single piece, in order that they might be 

 more susceptible of vibrations; but it ought to be considered, that 

 these organs would, by such a conformation, have been much exposed 

 to breaking, while, in consequence of their jointed form, they have the 

 advantage of regulating the degree of vibration at pleasure, as may 

 indeed be observed when insects listen with attention ; I mean, that 

 the joints of the antennas perform the same functions as the chain of 

 small bones in the chamber of the human ear, inasmuch as they form 

 a similar chain, and transmit the vibrations of the air to the auditory 

 pulp. 



The form of the antennas appears to be altogether independent of 

 their functions ; since their forms are so variously diversified, it would 

 be necessary to admit numerous differences of function according to 

 difference of conformation. 



Varieties in the forms of Antennae. 



The principal objection which can be made to my opinion* upon 

 the functions of the antennas, is that spiders (Arachnidce) being without 

 these organs, ought in consequence to have no sense of hearing, 

 though very conclusive observations prove the contrary. To this I 

 reply, that the organ by which these animals perceive sounds is per- 

 haps different from that of insects, and altogether internal, as is fre- 

 quently the case in vertebrated animals. Besides, whatever the sense 

 may be that resides in the antennas, spiders ought to be without it, 

 unless another apparatus be substituted in its stead. Now, as antennas 

 are found in most articulated animals having a solid skin, and as their 

 nerve is one of the largest in the body, it is not a little evident that 



* M. Straus-Durckheim does not seem to be aware that this opinion was started by 

 Bonsdorf, and adopted by Gbze and Christ, as well as by some English writers. — Ed. 



