THE VEGETATIVE OEGANS OE PLANTS. 251 



cut off just above the ground, underwent great and con- 

 tinual variation from hour to hour (during rainy weather) 

 when the soil was saturated with water and when the 

 thermometer indicated a constant temperature. Hofmeister 

 states that the formation of new roots and buds on the 

 stump is accompanied by a sinking of the water in the 

 pressure-gauge. 



Absorption of Nutriment from tlie Soil. — ^The food of 

 the plant, so far as it is derived from the soil, enters it in 

 a state of solution, and is absorbed with the water which is 

 taken up by the force acting in the rootlets. The absorp- 

 tion of the matters dissolved in water is in some degree 

 independent of the absorption of the water itself, the plant 

 having, to a certain extent, a selective power. 



3. The Hoot as a Magazine. — In fleshy roots, like 

 those of the carrot, beet, and turnip, the absorption of 

 nutriment from the soil takes place principallyj if not en- 

 tirely, by means of the slender rootlets which proceed 

 abundantly from all parts of the main or tap-root, and es- 

 pecially from its lower extremity ; while the fleshy portion 

 serves as a magazine in which large quantities of pectose, 

 sugar, etc., are stored up during the first year's growth 

 of these, (in our latitude,) biennial plants, to supply the 

 wants of the flowers and seed which are developed the 

 second year. When one of these roots is put in the 

 ground for a second year and produces seed, it is found to 

 be quite exhausted of the nutritive matters which it pre- 

 viously contained in so large quantity. 



In cultivation, the farmer not only greatly increases the 

 size of these roots and the stores of organic nutritive ma- 

 terials they contain, but by removing them from the 

 ground in autumn, he employs to feed himself and his cat- 

 tle the substances that nature prinjarily designed to nour- 

 ish the growth of flowers and seeds during another sum- 

 mer. 



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