344 General Biology 



tearing of many tiny nerves will certainly not cause any organism to 

 react normally. 



Mclndoo has recently shown that the chief olfactory organs (at 

 least in the honey bee) are located near, or on the base of the leg. 



HEARING 



As various insects produce noises of many kinds, we infer they must 

 hear, though definite evidence has not been forthcoming up to this time. 

 Flies and bees "buzz" by a rapid motion of the wings, while the singing 

 of the male cicada is produced by a rapid vibration of a pair of mem- 

 branes on the first abdominal segment, and a resounding drum-like mem- 

 brane within the thorax. Many beetles form a squeaking noise by 

 rubbing their wing-covers against some rasp-like portion of their body 

 while grasshoppers rub their hind legs against the wing-covers and also 

 rub front and hind wings together. 



Crickets and katydids (Fig. 224) have a definite scraper on the base 

 of one wing-cover and a file-like apparatus on the base of the other. 

 These are rubbed together causing the neighboring membrane to vibrate 

 and produce the "chirp." 



As such "chirps" or calls are answered by their mates it must be 

 assumed that some hearing takes place. 



The grasshoppers have a large auditory organ on each side of the 

 first abdominal segment consisting of a surface membrane, or tympanum, 

 stretched across a cavity, on the inside of which two tiny processes 

 something like the ear-bones of the frog are found. There are also 

 similar membranes on the tibia of some insects which probably serve 

 as auditory organs. 



A male mosquito will vibrate its antennae when a tone is produced 

 on a tuning fork of the same pitch as that made by the wings of the 

 female, so that it may be that in the mosquito the antennae have some 

 auditory function. 



THE MUSCULAR SYSTEM 



As in all animals possessing an exoskeleton, the muscles must be 

 attached on the inner surface of the skeleton (Fig. 221). Each of these 

 muscles is innervated by nerves, however, just as in animals possessing 

 endoskeletons and each muscle moves by a series of complicated pulley- 

 like arrangements already described in the crayfish. 



THE REPRODUCTIVE SYSTEM 



Among all insects there are two sexes, the male usually being the 

 smaller, more active and more brightly colored. It has been suggested 

 that the reason for this is that the handsomer males are thus able to 

 attract mates more often than those less handsome. Consequently the 

 young born of such more handsome fathers, were also handsome, thus 



