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ELEMENTARY STUDIES IN INSECT LIFE 



CHAPTEE V 

 FORM AND FUNCTION 



HEIST the study of Physiology is under 

 way, comparative anatomy lends in- 

 terest and adds value to the instruc- 

 tion. The material may be procured 

 easily, and the few facilities required 

 for bringing the subject-matter intel- 

 ligently before the class favor an anatomical study of 

 the skeleton or external anatomy of the grasshopper. 

 The skeleton of the grasshopper, 1 the history of which 

 we have already studied, will be the subject considered. 

 A word in beginning concerning skeletons. As every 

 student of physiology is taught, skeletons are of two 

 kinds: endo-skeletons, or skeletons within the body and 

 surrounded by muscles; exo-skeletons, or those without 

 the body, having all muscles on the interior. The skele- 

 tal structure of man comes under the first class ; the 

 rigid outer structure of insects under the second class. 

 Every one who has studied human physiology remem- 

 bers among the first topics to be found in the text is 

 1 Uses of the Skeleton," and in answer to the question, 

 " What are the uses of the skeleton ? " if he were per- 

 mitted to use another's language instead of his own he 

 would say, " To give form to the body, to protect the 

 delicate organs, to furnish attachments for the mus- 

 cles, to serve as levers for locomotion." And when an 



^Melanoplus differentialis. 



