LIVING AND NON-LIVING OBJECTS. 37 



recognize that some of the parts of living objects are not 

 themselves alive. For example, the last year's leaves 

 of the white oak are not living, although they may still 

 be on the tree late in the spring. Similarly, the outside 

 bark of a large tree has many layers that are not living, 

 and the heart-wood of such a tree is not alive. In our 

 own case, the enamel of the teeth is not living substance, 

 nor is the solid material in our bones, although it is an 

 intimate part of a living object. In the same way, we 

 know that the water and the oxygen in a living body 

 are no more alive than the same substances in the pond 

 or in the atmosphere. So fats and starches, and many 

 other substances found in our bodies, are not living and 

 have never been so. All living objects are thus made up, 

 in part, of non-living matter. 



49. How do living objects differ from non-living objects? 



As a result of the laboratory work of the last chapter, 

 how do you distinguish living objects from objects that 

 have never been alive? How from objects of the same 

 kind that have been, but are no longer, alive? 



The chief differences between living objects and those 

 that have not been closely associated with, or produced 

 by, life are differences (i) in organization and (2) in powers. 



To be organized means essentially to have different 

 parts, which do different work and are bound together 

 in such a way that each part contributes to the whole 

 individual and is, in turn, supported by the other parts. 



Organization in living objects may be treated under 

 three phases: (i) gross organization; (2) cellular organi- 

 zation; and (3) protoplasmic organization. The powers 

 and activities of the living objects are believed to grow 

 out of their organization. 



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