i8 



FIELD ZOOLOGY. 



Fig. 8. — Locust from lateral aspect (left 

 wings removed), showing {ao) auditory organ. 

 (Kellogg.) 



This may be called negative proof of the power of hearing ; 



but there is also positive proof in the discovery of the pos- 

 session of auditory 

 organs by many in- 

 sects. (Fig. 7.) Our 

 common grasshop- 

 pers, katydids, 

 crickets, and mosqui- 

 toes have such or- 

 gans. As with the 

 other senses of in- 

 sects, we find the 



organ of this sense in several different parts of the bodies 



of these simple animals. The higher animals we call 



higher because of the centralization of related functions ; 



and that centralization 



has meant the concen- 

 tration of many formerly 



distributed senses into 



one ganglion or knot of 



our nerve cord — the 



brain. The low animals, 



then, are the ones in 



which these senses are 



most widely separated 



as to locality and least 



differentiated as to kind. Fig. 9. — Diagram of longitudinal section 

 This miffht be said '^■'""g'' ^^^^ ^^^ second antennal segments 

 - , , , , , , of a mosquito, male, showing complex audi- 



further: the more closely ^^^^ „^g^„ ^„^p„3^d of fine chitinous rods, 



related in point of posi- nerve fibers, and nerve cells. (Kellogg, after 

 tion these sense organs Child; greatly magnified.) 



are to the brain, the higher the insect in the scale of life 

 development. 



