280 PRACTICAL LESSONS IN SCIENCE. 



for observation, and have several large specimens preserved in 

 alcohol for dissection. In studying the grasshopper note the 

 general divisions of the body ; examine carefully the antennae and 

 eyes, using the lens in looking for the ocelli. Dissect out and 

 place by itself each one of the mouth parts. Notice the divisions 

 of the thorax, and compare them in size and form and as to the 

 appendages they bear. Note the position of the anterior wings 

 when folded, open these wings so that the anterior margin shall 

 be at right angles with the body, and then note the position of 

 the inner wing while folded; spread it out, noting carefully how it 

 was folded. Compare the framework of the two pairs of wings ; 

 also compare them as to size, shape, color, texture, position 

 and use. Study the legs; note their number, arrangement 

 and mode of attachment, and the parts of each. Notice the 

 different ways in which the grasshopper travels, and how he 

 makes sounds. 



Note the number of segments in the abdomen and the two 

 longitudinal grooves on its under surface. That part of the ab- 

 domen between the grooves is the sternum, the side is the pleu rum 

 and the upper part the tergum; and the corresponding parts of a 

 segment are the sternite, pleurite and tergite. Note the spiracles 

 or breathing pores on the sides of the abdomen. On the sides of 

 the first segment find a pair of thin oval membranes called tym- 

 pana, which some think are an auditory apparatus. The four 

 short setae, which may be discovered at the end of the abdomen 

 of a female grasshopper, form an ovipositor by which she can 

 make a hole in the earth as deep as the abdomen is long, at the 

 bottom of which she deposits her eggs. Dissecting a large female 

 grasshopper under water, as in the case of the crayfish, one may 

 make out the air sacs and tubes, the egg masses and the alimen- 

 tary canal. 



The Orthoptera include Forficulidse or earwigs, the Blattidse 

 or cockroaches, the Phasmidss or walking sticks, the Acridiidse or 

 grasshoppers, the Locustidse or locusts, the Gryllidse or crick- 

 ets, the TermitidsBor white ants, the Ephemeridae or the Mayflies, 

 the Libellulidse or dragon flies, and others. They are all inter- 



