290 Adventures in Scenery 



tinguished by the naked eye have lived in myriad numbers on 

 the sea bottoms, and their tiny skeletons now make up vast beds 

 of shale rock. Diatoms were living things, their bodies com- 

 posed largely of carbon and hydrogen, their skeletons or tiny 

 shells being of mineral matter (mostly silica). Diatoms, it 

 may be explained, are minute organisms, microscopically small, 

 that are near the borderland between plants and animals. Care- 

 ful study by specialists has determined that diatoms give off 

 (exhale) oxygen in their life processes and take up (from the 

 air or from water) carbon dioxide. Carbon dioxide is a chem- 

 ical combination of carbon and oxygen, which is given off 

 (exhaled) by animals. In fact the dividing line between plants 

 and animals is right there. Plants breathe in (inhale) carbon 

 dioxide and exhale oxygen. The carbon is built into plant 

 tissue. Animals inhale oxygen, which in their bodies is com- 

 bined with carbon, hydrogen and nitrogen to form animal tis- 

 sue. Some of the carbon in animal bodies is burned or oxidized 

 and is given off (exhaled) as carbonic acid (CCX) . Thus plants 

 and animals thrive together plants give off oxygen, which 

 animals need, and take up carbon dioxide, which animals throw 

 off (exhale). This explains why house plants are desirable in 

 living rooms. They give off oxygen and take up the poisonous 

 carbon dioxide which has been exhaled by human beings. 



So because they throw off oxygen and breathe in carbon 

 dioxide it has been found that diatoms are of vegetable char- 

 acter. Myriads of animals have lived during the geologic ages, 

 and their bodies are composed mainly of the elements carbon, 

 hydrogen, oxygen, and nitrogen. Whether oil has been dis- 

 tilled from myriads of animal forms again we do not know. 

 That great numbers and great variety of animals and plants 

 have lived during the geologic ages is known. But no oil has 

 ever been discovered in many formations in which great num- 

 bers of organic forms lived. So, where the oil comes from we 

 do not know. 



