526 The Animal Kingdom 



The brain of the grasshopper is dorsal and anterior to the esopha- 

 gus, and is composed of three pairs of ganglia. These supraesopha- 

 geal ganglia are connected by two connectives which pass around the 

 esophagus and join the subesophageal ganglia which is also formed of 

 three pairs. From the dorsal ganglia, nerves pass to the various sense 

 organs of the head. From the subesophageal ganglia, the ventral nerve 

 cord passes to the posterior part of the abdomen. On the double ven- 

 tral nerve cord are located paired ganglia. Each segment of the thorax 

 contains a pair, but in the abdominal region there are but five gangli- 

 onic pairs, there being considerable coalescing of elements. From these 

 ganglia, lateral nerves are given off to the various regions. 



The grasshopper has an autonomic nervous system which controls 

 the visceral activities. There are two portions to this: one supplies 

 the organs of the anterior region and arises from the brain ; the other 

 supplies the organs of the posterior region and arises from the last ab- 

 dominal ganglion. 



The grasshopper is well supplied with sense organs, including the 

 compound eyes and the ocelli. Tactile hairs are present on the an- 

 tennae, the legs, and on various parts of the body. Taste receptors are 

 present on the various mouth parts. Olfactory organs are found on 

 the antennae. Finally there is the device for receiving sounds, the 

 tympanic membrane of the first abdominal segment. 



The grasshopper produces sounds by rubbing the hind femurs 

 which are provided with minute teeth across the wing veins. This 

 sets the wings to vibrating, producing the typical whirring sound which 

 varies with the species. 



In some ways, the most highly developed system of the insects is 

 the reproductive one. Tremendous numbers of eggs are produced and 

 at times the population rises to unbelievable totals. In the male, the 

 testes are located dorsal to the intestine. Each of the two testes is 

 composed of a large number of slender tubules. These tubules or fol- 

 licles unite to form the vas deferens of each testis. Each vas deferens 

 widens into a seminal vesicle. These two vasa deferentia join to form 

 a single ejacidatory duct which ends in the penis opening ventral to 

 the anus. Where the two vasa deferentia unite, there is an accessory 

 gland from each side. 



In the female, the paired ovaries are located dorsally and at times ap- 

 pear to occupy the whole dorsal part of the animal. Each ovary is 

 composed of masses of tubes or ovarioles, where the eggs are pro- 



