. Beginners' Zoology . 66 BEGINNERS ZOOLOGY Outward ? Backward ? Can you give reasons for the posk*tion of each pair ? (Suggestion: What is the use of eachpair?) If an organ is modified so that it is suited to servesome particular purpose or function, it is said to be special-ized. Are any of the legs specialized so that they servefox a purpose different from that of the other legs? The leg of a grasshopper (as of all insects) is said tohaveyfw parts, all the small parts after the first four partsbeing counted as one part and called the foot. Are all thelegs similar, that is, do the short and
. Beginners' Zoology . 66 BEGINNERS ZOOLOGY Outward ? Backward ? Can you give reasons for the posk*tion of each pair ? (Suggestion: What is the use of eachpair?) If an organ is modified so that it is suited to servesome particular purpose or function, it is said to be special-ized. Are any of the legs specialized so that they servefox a purpose different from that of the other legs? The leg of a grasshopper (as of all insects) is said tohaveyfw parts, all the small parts after the first four partsbeing counted as one part and called the foot. Are all thelegs similar, that is, do the short and the long joints in allcome in the same order? Numbered in order from the. Fig. 109. — How a Grasshopper Fig. iio. — How a Spider Walks. Walks. body, which joint of the leg is the largest — the first, sec-ond, third, or fourth ? Which joint is the shortest? Theslenderest? Which joint has a number of sharp points orspines on it ? Find by experiment whether these spinesare of use in walking (Fig. 106). Jumping. what order are the legs used in walking ? How manylegs support the body at each step ? All animals that have ears have ways of communicatingby sounds. Why would it be impossible for the grasshop-per to have a voice, even if it had vocal cords in itsthroat? The male grasshoppers of many species make achirping, or stridulation, by rubbing the wing against theleg. Look on the inner side (why not outer side ?) of the INSECTS 67
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