THE GRASSHOPPER AND OTHER ORTHOPTERA 9 



ventral side of the body. These ganglia are connected 

 by a double nerve cord, the two parts of which lie very 

 close together and appear in the abdomen as a single strand. 

 There is a paired ganglion in each of the three segments 

 of the thorax and five ganglia in the abdomen. From 

 these ganglia nerves are given off to the muscles and sense 

 organs of neighboring parts. 



Movements of parts of the body are effected by means 

 of muscles. The thorax contains muscles of unusually 

 large size which are used for moving the wings. Muscles 

 'act by contracting and thereby producing movement in 

 the parts upon which they are inserted. The impulses 

 causing the contraction are conveyed by nerves which 

 pass to the muscles from the ganglia. 



The ovaries, or organs for producing the eggs, are situa- 

 ted in the abdomen of the female. They present the 

 appearance of paired masses of eggs in various stages of 

 growth from an exceedingly minute size to the lull grown 

 egg. When the eggs have attained their full size they are 

 discharged from the ovary into a tube, the oviduct. A 

 short distance from the posterior end of the body the two 

 oviducts unite to form a median duct which opens between 

 the bases of the valves of the ovipositors previously de- 

 scribed. During their passage down the oviduct the 

 eggs become surrounded by a sticky substance secreted by 

 certain glands which open near the junction of the two 

 oviducts. It is this sticky substance which causes the 

 eggs to adhere in masses after they are laid and which 

 subsequently protects them 'from the injurious effects of 

 moisture. 



The male organs corresponding to the ovaries are called 

 the spermaries or testes. They lie in the abdomen above 

 the intestine and are so closely united that they appear 

 as a single organ. They give rise to slender ducts which 



