THE GRASSHOPPER AND THE SNAIL 51 



the locust. The sound-waves striking" against these thin 

 tightly stretched bits of the body wall, set them into 

 vibration, and these vibrations stimulate a tiny nerve 

 which touches each tympanic membrane on the inside 

 and leads to one of the internal nerve-centers. This is 

 a much simpler kind of ear than we possess, and the 

 locust probably cannot hear nearly as well as we can. 

 Note on each side of each abdominal body-ring (except 

 the last) a tiny blackish spot. These are breathing 

 pores or spiracles like those of the silkworm (see p. 

 13). The locust does not take i^n air through nostrils 

 on the head or through the mouth, but through these 

 numerous pores. There is also a spiracle near each 

 tympanum, and one on each side of the thora.x near the 

 insertion of the middle legs. At the very tip of the abdo- 

 men are several small projecting parts which differ in the 

 male and female. The female has two pairs of strong, 

 curved, pointed pieces called the ovipositor or egg-laying 

 organ. When the locust is ready to lay its eggs, by 

 means of this strong ovipositor it bores a hole in the 

 ground into which the abdomen is pushed and the eggs 

 laid at the bottom. The male locust has a swollen, 

 rounded, abdominal tip, with a few short inconspicuous 

 pieces on the upper surface. 



Examine now a live locust and see how it uses its legs 

 in walking and hopping ; how it moves its jaws sidewise, 

 not up and down as with us ; how its antennc'e keep 

 "feeling" about in front of it when it is walking; how 

 the abdomen keeps up a slight but distinct and regular 

 expanding and contracting. This movement forces air 

 in and out of the body through the spiracles ; it is the 

 breathing motion. 



Make a drawing from lateral view of the whole body 

 of the locust, showing and naming all the parts studied. 



For a more detailed account of the external structure 



