SOIL AND ITS RELATION TO ROOTS 83 



brought in from the neighboring market gardens. But we some- 

 times forget that our great staple crops, wheat and other cereals, 

 potatoes, fruits of all kinds, our cotton crop, and all plants we make 

 use of grow directly in proportion to the amount of raw food ma- 

 terials they take in through the roots. When we also remember 

 that many industries within the cities, as mills, bakeries, and the 

 like, as well as the earnings of our railways and steamship lines, are 

 largely dependent on the abundance of the crops, we may recognize 

 the importance of what we have read in this chapter. 



Food Storage in Roots of Commercial Importance. — Some plants, 

 as the parsnip, carrot, and radish, produce no seed until the second 

 year, storing food in the roots the first year and using it to get an 

 early start the following spring, so as to be better able to produce 

 seeds when the time comes. This food storage in roots is of much 

 practical value to mankmd. Many of our commonest garden 

 vegetables, as those mentioned above, and the beet, turnip, oyster 

 plant, sweet potato and many others, are of value because of the 

 food stored. The sugar beet has, in Europe especially, become 

 the basis of a great industry. 



Reference Books 



elementary 



Hunter, Laboratory Problems in Civic Biology. American Book Company. 

 Bigelow, Applied Biology. The Macmillan Company. 



Coulter, Plant Life and Plant Uses, Chaps. Ill, IV. American Book Company. 

 Mayne and Hatch, High School Agriculture. American Book Company. 

 Moore, The Physiology of Man and Other Animals. Henry Holt and Company. 

 Sharpe, Laboratory Manvxxl in Biology, pp. 73-87. American Book Company. 



ADVANCED 



Coulter, Barnes, and Cowles, A Textbook of Botany, Part II. Amer, Book Co 

 Duggar, Plant Physiology. The Macmillan Company. 

 Goodale, Physiological Botany. American Book Company. 

 Green, Vegetable Physiology, Chaps. V, VI. J. and A. Churchill. 

 Kerner-Oliver, Natural History of Plants. Henry Holt and Company. 

 MacDougal, Plant Physiology. Longmans, Green, and Company. 



