FRUITS AND THEIR USES 57 



The Struggle for Existence. Those plants which provide best 

 for their yoim^ arc usually the most successful in life's race. Plants 

 which combine with the ability to scatter many seeds over a wide 

 territory the additional characteristics of rapid growth, resistance 

 to dangers of extreme cold or heat, attacks of parasitic enemies, 

 inedibility, and peculiar adaptations to cross-pollination or self- 

 pollination, are usually spoken of as weeds. They flourish in the 

 sterile soil of the roadside and in the fertile soil of the garden. By 

 means of rapid growth they kill other plants of slower growth by 

 usurping their territory. Slow-growing plants are thus actually 

 exterminated. Many of our common weeds have been introduced 

 from other countries and have, through their numerous adaptations, 

 driven out other plants which stood in their way. Such is the Rus- 

 sian thistle. First introduced from Russia in 1873, it spread so 

 rapidly that in twenty years it had appeared as a common weed 

 over an area of some twenty-five thousand square miles. It is 

 now one of the greatest pests in our Northwest. 



Problem IX. The economic value of some fruits. (Labora- 

 tory Manual, Prob. 7A'J 



Economic Value of Fruits. Our grains are the cultivated prog- 

 eny of wild grasses. Domestication of plants and animals marks 

 epochs in the advance of civilization. The man of the stone age 

 hunted wild beasts for food, and lived like one of them in a cave or 

 wherever he happened to be; he was a nomad, a wanderer, with 

 no fixed home. He may have discovered that wild roots or grains 

 were good to eat ; perhaps he stored some away for future use. 

 Then came the idea of growing things at home instead of digging or 

 gathering the wild fruits from the forest and plain. The tribes 

 which first cultivated the soil made a great step in advance, for they 

 had as a result a fixed place for habitation. The cultivation of 

 grains and cereals gave them a store of food which could be used 

 at times when other food was scarce. The word "cereal" (derived 

 from Ceres, the Roman Goddess of Agriculture) shows the impor- 

 tance of this crop to Roman civilization. From earliest times the 

 growing of grain and the progress of civilization have gone 

 hand in hand. As nations have advanced in power, their 

 dependence upon the cereal crops has been greater and greater. 



