A STUDY OF THE GRASSHOPPER 19 



ach. They secrete a fluid which aids in digestion. The 

 Malpighian tubules are a number of fine hair-like tubes which 

 arise from the alimentary canal at the point of union of the 

 stomach and the large intestine. They gather from the blood 

 and empty into the intestine certain waste products, thus 

 functioning something like the kidneys of higher animals. 



The muscular system comprises many sets of muscles, the 

 largest and strongest of which are in the thorax. As there is 

 no internal skeleton the muscles are attached to the hardened 

 portions of the body-wall. 



The respiratory system consists of series of small many- 

 branching tubes called trachea. Their walls are thin and elastic. 

 The external openings of these, the spiracles, have already 

 been noted. From the spiracles short tubes lead to two lateral 

 trunks which send off branches to a pair of dorsal trunks. 

 These lateral and dorsal trunks send branches to all the 

 organs and tissues of the body. The air enters the tracheae 

 through the spiracles and is carried to all parts of the body, 

 where oxygen is given up to the tissues which need it, and the 

 waste carbon dioxide is carried away. 



The reproductive system of the female is easily dis- 

 tinguished if the female has been collected in the fall or late 

 summer before she has laid her eggs. At such a time almost 

 the whole abdomen will be filled by the pair of thin-walled 

 ovaries in which may be seen the masses of oblong, brownish 

 or yellowish eggs. Running from the posterior end of each 

 ovary is a small tube, the oviduct. These unite near the pos- 

 terior end of the body and form a single tube which opens 

 between the bases of the valves of the ovipositor. The repro- 

 ductive organs of the male are similar to those of the female 

 but much smaller. They consist of a pair of testes which lie 

 on the dorsal side of the posterior part of the stomach. Lead- 

 ing from the testes are two very small tubes, the vasa deferentia, 

 which unite to form a short tube that opens on the dorsal 

 surface of the last segment of the abdomen. These organs 

 cannot be easily distinguished unless the specimen is in just 

 the right condition. 



The nervous system is made up principally of a series of 



