CHAPTER V 



LIVING MATTER 



Questions. 1. Does life come from one particular part of the body, 

 like the heart or the blood, or is it in all parts ? 2. Why can some parts 

 of an organism be destroyed without killing the body, whereas it does 

 kill the body to destroy other parts ? 3. What is the smallest portion of 

 a plant or animal that can remain alive ? 4. What are the smallest plants 

 or animals ? 5. Are there any living things too small to be seen ? 



43. Protoplasm. A man has none of the organs that a tree 

 has ; a tree has none of the organs that a man has. Indeed, 

 animals differ so much from plants that it is difficult at first to 

 see how they can be so much alike in those three qualities 

 (growth, movement, and irritability) which distinguish living 

 things from non-living things. The solution to this difficulty is 

 found in the fact that the bodies of all organisms are made up 

 of a peculiar substance (or rather a mixture of substances) 

 which seems to have all the qualities of living bodies. This is 

 the stuff in living things that can grow ; this is the stuff that 

 moves ; this is the stuff that is irritable. 



The microscope shows this living stuff to be a slimy, or jelly- 

 like, substance something like the white, of egg in appearance. 

 Under a more powerful microscope it sometimes appears to 

 have many minute bubbles in it or to consist of an extremely 

 fine network. This stuff is called protoplasm (/>ro^o5, first; 

 plasma, forming material), and in all essential respects it seems 

 to be alike in all plants as well as in all animals. It is the proto- 

 plasm of a plant or of a kitten that grows. It is protoplasm in 

 the body of the Venus 's-fly trap or of a snake that moves when 

 the organism springs upon its victim. It is the protoplasm 

 of the geranium or of the worm that is sensitive to light. 



S6 



