^4 A MANUAL or ZOOLOGY 



of water to pass from it to the animal. Note any evidences 

 t^at the animal knows of the presence of food. Draw 

 a bristle over its back and note if one place is more^asi- 

 "tive tfian another. Pass your -band q[nickly by th^'jar. 

 Does it see? From the study so far what can be sai4 of 

 this animal as to special senses? With a pipette place 

 some carmine ground fine in water, close to the thorax. 

 What becomes of it? This will demonstrate how the ani- 

 mal breathes. 



II LOCUST. 



EXTERNAL ANATOMY— Note the segmented struct- 

 ure. There are three main groups of segments: head, 

 thorax, and abdomen. How many segments appear in the 

 head, thorax, ahd in the abdomen? The thorax is dis- 

 tinguished by five pairs of appendages. What are they? 

 Note the three divisions of the thorax. Compare the 

 segments of the abdomen with those of the head, in 

 reference to shape, structure, and distinctness. 



BODY WALL — Note the hard covering.the chitin. 

 The. uneven distribution of the chitin produces the defi- 

 nite portions, the sclerites. Examine the surface of the 

 specimen with hand lens. As the head is pulled note 

 that the membrane that holds it in place has very little 

 chitin, if any. Note the narrow furrows that separate the 

 sclerites, the sutures. In many places the sutures are not 

 distinct and the sclerites are fused. 



THE HEAD — Two divisions of the head are readily ■ 

 distinguished: the fixed portion, the cranium and the mov- 

 able portions, the appendages. The Fixed Parts of the Head: 

 two large rounded bodies, the compound eyes. They 

 occupy a large portion of the latero-dorsal portion of the 

 head. Study the compound eyes with the microscope. 

 Note the structure. Compare it with something you have 

 - already studied. Mate_dra.wingjtoJUustE8±e-ihe.^traciuce . 

 QLong.i)tJJifiae -eyes, -eephalad of the dorsal half of each 

 of the compound eyes find a small transparent body, the 

 simple eyes or ocelli. In a pit in center of cephalic sur- 

 face of head note a third simple eye. Note a large sclerite 

 surrounding the compound eyes, and bearing the simple 

 eyes, the epicranlum. A suture extends ventrad from the 



