352 



GENERAL SCIENCE 



FIG. 312. A Para- 

 mecium. 



little animals must of course come from the water, the 

 air, or the hay. They were there in a dormant state. 

 We simply adjusted conditions so that 

 these were favorable to their develop- 

 ment. Such an animal is called a para- 

 mecium (plural paramecia) (Figures 312, 

 313). It is a more complex organism 

 than the amoeba. Under the microscope 

 it is seen to have a somewhat regular 

 shape, to have the power of moving itself 

 by means of special parts of its cell, 

 called cilia, and to take its food through 

 a definite opening or mouth. 



Division of Labor. As we observe 

 animals higher in the scale of life we find 

 that certain parts of animals have a 

 definite work to do. A part of a plant or animal which 

 has a special work to do is called an organ. Thus we have 

 organs that take food ; organs that 

 digest food ; organs for the circula- 

 tion of blood and other fluids ; 

 organs of breathing ; organs of ex- 

 cretion ; organs of voluntary move- 

 ments ; organs of special senses ; 

 nerve organs ; organs of reproduc- 

 tion ; and organs of protection. 

 The refinements in the functions of 

 the various organs of an animal 

 determine its position in the scale 

 of life, just as the degree of the de- 

 velopment of the principle of " divi- 

 sion of labor " determines the civili- 

 zation Of a people. FIG. 313. Paramecia. 



