CHAPTER XXXI 

 LIVING THINGS 



177. Organic and Inorganic Bodies. In the early days of 

 science, philosophers regarded the universe as being made up 

 of three groups or kingdoms containing the animals, the 

 plants, and the minerals respectively. More extended study 

 has shown that there are really only two kingdoms, the living 

 or organic, containing all the animals and plants, and the 

 non-living or inorganic, containing the rocks, minerals, air, 

 water, and the rest of creation. Living things are composed 

 of the same chemical elements that occur in other forms of 

 matter, but they are sharply distinguished from them by 

 being organized into forms of definite structure which, under 

 the influence of a mysterious force called life, are capable of 

 feeling, moving, growing or increasing in size, and reproducing 

 or increasing in numbers. In living things, also, each part 

 is dependent to a certain extent on the whole body, while in 

 the non-living no such dependence exists. When a thing is 

 alive, it is continually adding new matter to its substance, and 

 as constantly discarding other matter no longer of use. Only 

 living things can do this; in fact, when the adding process, or 

 assimilation, and the discarding process, or excretion ceases, 

 death ensues and the body ultimately returns again to the 

 chemical elements from which it was made. 



178. Cells. The living parts of both animals and plants 

 consist of a substance called protoplasm which is a semi-fluid 

 much like the white of an egg in appearance. The smallest 

 living unit of protoplasm is called a protoplast or cell. Such 

 cells are much too small to be seen with the naked eye, but 



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