4 



Plants Provide lor Tneniselves 

 ana me Animals 



The existence of the living world depends upon green plants since they 

 alone make the food that is essential both to themselves and the animals. 

 Through the long past animals became agile of movement, swimming, running, 

 or flying, developed keen senses, and became alert to their surroundings. Great 

 numbers of them fed upon plants, and as time went on many became carni- 

 vores and devoured their fellow animals. But none of them could make their 

 own food from the chemical elements about them. Human beings are no better 

 off than other animals. Although they have extraordinary capabilities, their 

 existence finally depends upon the carbohydrate foods, the sugars and starches 

 that green plants make by photosynthesis. After years of study it now seems 

 that photosynthesis may be understood, but to furnish the world with food 

 is another and probably much more difficult matter. 



The meals of Eskimos are far removed from the cabbage patch, yet they 

 too originate in plants. Eskimos live on seal meat and fish and birds, but ulti- 

 mately all these are fed by the microscopic plants which swarm in the arctic 

 seas. The seals and the birds feed upon the fishes; big fishes eat little fishes 

 and both devour little copepods by billions; and finally copepods feed ex- 

 clusively upon microscopic plants, mainly diatoms (Fig. 4.1). Thus, the 

 substance of the Eskimo's diet is in origin mainly digested diatoms. For the 

 dweller farther south in America or Europe the food chain is different, usually 

 beginning with grass and ending with beef, or starting with diatoms and ending 

 with codfish. Grass can live without cattle and diatoms without codfishes but 

 no animals can exist without plants somewhere in their food story. Plants and 

 animals are fundamentally similar. A sunflower and a horse look strikingly 

 different; yet they are both living organisms existing basically in the same 

 way. 



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