PART IV. ANIMALS AS LIVING ORGANISMS 



CHAPTER XII 

 ANIMAL ORGANISMS. THE HUMAN MACHINE 



Problems: To understand what is meant by physiological division 

 of labor. 



To learn the functions performed by the higher animals. 



To obtain a general understanding of the parts of the human machine 

 and their uses. 



Laboratory Suggestions 



Exercise. Adaptations in a living frog. Comparison of external organs with 

 homologous structures in man. 



Demonstration. Review to show that the human body is a complex of cells. 



Demonstration, by means of (a) human skeleton and (5) manikin, to show 

 the position and gross structure of the chief organs of man. 



The Needs of Living Things. — We have already found that the 

 primary needs of plants and animals are the same. Both need 

 food. Both need to digest their food and to have it circulate in a 

 fluid form to the cells where it will be used or stored. Both need 

 oxygen so as to release the energy locked up in food. And both 

 need to reproduce if their kind is to be continued on the 

 earth. What is true of plants and animals is true of man, so far 

 as his primary physical needs are concerned. 



The Needs of Simple and Complex Animals the Same. — The 

 simplest animal, a single cell, has the same needs as the most 

 complex. The Paramecium feeds, digests, oxidizes its food, and 

 releases energy. It is the cells in the body of a worm or a fish 

 or a frog that use food and do work. The cells of the human body, 

 built up into tissues, have the same needs and perform the same 

 functions as the cell body of the Paramecium. It is the cells of 

 the body working together in gi'oups as tissues and organs that 

 make the complicated actions of man possible. 



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