ORGANIC AND INORGANIC BODIES. 17 



15. The growth of organized bodies proceeds from within, 

 that of inorganic matter from without. If minerals increase 

 in size, it is by attracting matter to their external surface, 

 while animals and vegetables grow by a process, called 

 nutrition ; that is, laying hold of nutritious substances and 

 converting them to their own nature, by means of internal 

 organs. 



16. Organized bodies possess the power of being affected 

 with disease and recovering from it. They also have a 

 determinate duration, beyond which they do not often live. 

 This period varies for each species of animal and vegetable. 

 Some insects live but a single day ; most plants live but a 

 single year ; but some trees, such as the oak and cedar, are 

 supposed to live more than two thousand years. The average 

 duration of human life in this country is not over thirty years. 



17. But the great distinction between a living being and 

 an inorganic body is, that the former carries on a number of 

 processes, not performed by the latter. A plant, for example, 

 absorbs food, converts it into its own proper substance, 

 arranges it into bark, wood, leaves, and other organized 

 structures, grows, arrives at maturity, generates and main- 

 tains a certain degree of heat, decays, and finally perishes. 

 No such phenomena are exhibited by a stone, or other inor- 

 ganic bodies. These processes, therefore, are called vital, be- 

 cause they are peculiar to a state of life, and afford characters 

 by which a living being is distinguished from all others. 



18. Organized beings are divided into two classes, animals 

 and vegetables, differing from each other in several well- 

 known features. 



19. Sensation and voluntary motion are possessed by ani- 

 mals, but not by vegetables. Had animals no sensibility or 

 feeling, they could not know their wants ; and if they knew 

 them but had not the power of motion, they would perish for 

 want of food ; hence the necessity of these two faculties 

 being joined together. 



20. An animal, like a plant, receives food, transforms it into 



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