THE LIVING STUFF 



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that bodies organized in such very different ways come to be 



so much alike in those three points that are said to distinguish 

 living things from non-living ? 



34. Protoplasm. The answer to this 

 question is to be found in the fact that 

 in the bodies of all organisms there is 

 a peculiar substance (or rather a mix- 

 ture of substances) which seems to 

 have all the qualities of living bodies. 

 This seems to be the stuff that can 

 grow ; this is the stuff that moves ; this 

 is the stuff that is irritable. When 

 seen under the microscope this living 

 stuff seems to be a slimy, or jellylike, 

 substance something like the white 

 of egg in appearance. Under a more 

 powerful microscope it sometimes ap- 

 pears to have many minute bubbles in 

 it, or to consist of an extremely fine 

 network. This stuff is called proto- 

 plasm, and in all essential respects 



it seems to be alike in all plants as well as in all animals. 

 It is the 



protoplasm of 



a plant or of 



a kitten that 



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Protoplasm moves 



The arrows indicate the stream- 

 ing of the protoplasm within 

 the cells 



grows. It is 



protoplasm in 



the body of 



the Venus's 



flytrap 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 the light. 



FIG. 3. Diagram of a cell 



The mass of the cell content consists of the protoplasmic network, 



with the coarser-grained nucleus. Within the protoplasm are more 



solid bodies, and droplets of more liquid substances 



