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 might be Said through ^ rst anc * seconc l antennal segments 

 r ' -i , of a mosquito, male, showing complex audi- 



lurtner:tfie more closely toryorgan compose d of fine chitinous rods, 



related in point Of pOSl- 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. 



