ACBIDIUM. 165 



crawling? How many times its length can a grasshopper jump? 

 Why are wings needed? 



4. During late summer and autumn you may find individuals 

 depositing eggs. See if you can determine how the end of the 

 body is worked into the ground. 



For study it is desirable to use a rather large, freshly killed 

 or alcoholic specimen. 



The body is divided into three well-marked regions. 



1. The Head. Is it movable? Does it need to be as mova- 

 ble as your own head ? It bears several organs. 



(a) The compound eyes. Examine one with a lens or remove 

 its outer covering and examine it with a compound microscope. 

 You should understand the structure of the whole eye and how 

 it gives a single visual image. 



(6) The ocelli, three in number, one near the middle of the 

 front part of the head and the others placed near the bases of 

 the antennae. 



(c) The antenna. Why are they so flexible? Examine one 

 with a microscope and notice the spines. What are these for? 



(d) Mouth parts. These should be studied later. 



2. The Thorax. Why should it be large and comparatively 

 firm? This portion is more or less distinctly divided into three 

 parts, each of which carries a pah* of legs. 



(a) Compare the three legs of one side. Do they have the 

 same number of segments? Do all of the joints of the leg move 

 in the same plane? The five divisions of a leg are, beginning 

 with the basal end: coxa, trochanter (immovably joined to the 

 coxa in the leaping legs), femur, tibia, and tarsus, which is com- 

 posed of four movable pieces. Why do the femurs of the leap- 

 ing legs differ from the femurs of the other legs? Determine 

 how the foot is arranged to hold to objects. Have you noticed 

 a grasshopper settle its feet preparatory to jumping? Examine 

 the joint between the femur and tibia. 



(6) Examine the wings and notice their size, shape, places 

 of attachment, and general character. Do they apparently 

 have different functions to perform? Notice how the posterior 



