ORGANISMS 3 



The stone, for example, is worn into fine particles of 

 dust by ceaseless grinding against sand and stone ; moun- 

 tains are broken into rocks and loose earth by frost and 

 washed down into the valleys by rain; wood decays to 

 the carbon dioxide and water from which the plant 

 built it. 



Multiplication of organisms. Organisms also differ 

 from non-living things in their power to produce new 

 organisms. In the lower forms of both plants and 

 animals, this process of reproducing or continuing life 

 has its simplest example in the division of the adult 

 into two or more young individuals, which, after they 

 have developed into maturity, again divide. In this 

 way, the species is rapidly multiplied, and death and 

 decay through old age are avoided. 



In higher forms of plants and animals, the process 

 of reproduction consists in the development of the 

 young organism as an offshoot or bud from the adult. 

 When capable of independent development, it is set 

 free as a young plant or animal and thereupon begins 

 a new life, in which lies this same power of starting 

 young organisms. 



Organic substances. The substances which plants 

 and animals produce, are called organic substances, since 

 they are dependent for their existence upon the life 

 and activity of plant and animal organisms. From 

 plants come such organic substances as wood, cotton,, 

 hemp, oil, flour, starch, sugar, coal, coal oil, paraffin 

 and natural gas. From animals come such substances as 

 flesh, leather, hair, wool and silk. 



Inorganic substances. In contrast to these are inor- 

 ganic substances, which are found in nature independent 

 of plant and animal life, such as air, water, minerals 

 (except coal in its various forms) and metals. 



