CHAPTER XII 



SOME OF THE LIFE PROCESSES 



You may bring up a dog on the food of a man, and yet you cannot make a 

 man of him. — John Burroughs 



Organ Systems. When we first began to study the insects 

 there was little reason to make comparisons between them 

 and our own bodies. But now that we have finished the 

 study of this group let us begin to make some comparisons 

 between what we have learned about insects and what we 

 previously knew about our own bodies. In spite of the dif- 

 ferences in form, we call many of the parts by the same 

 names in the two bodies, chiefly because they perform 

 somewhat similar or identical functions. The leg of a grass- 

 hopper with its many joints, its skeleton on the surface and 

 muscles inside the skeleton, is very different from the human 

 leg, yet both of them serve for locomotion. Similarly, in 

 the grasshopper we found organs of digestion and circula- 

 tion, a respiratory system, an excretory system, and a re- 

 productive system, all of which in functions correspond to 

 parts of our own bodies. 



Likenesses of Living Things. In spite of difference in struc- 

 ture there are a few things which all living animals do, no 

 matter how complicated or how simple they may be. They 

 have the power of taking lifeless food material and making 

 it over into part of their living bodies. As a result of the 

 energy which they derive from this food they live and 

 respond to outside forces which act upon them. Finally, 



they have the ability to grow and produce other individuals 



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