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CHAPTER II. 



OF THE ROOT. 



It is the business of the root to absorb nutriment from the 

 soil, and to transmit it upwards into the stem and leaves ; and 

 also to fix the plant firmly in the earth. Although moisture is, 

 no doubt, absorbed by the leaves and bark of all, and by the 

 -stems of many plants, yet it is certain that the greater part of 

 the food of plants is taken up by the roots ; which, hence, are 

 not incorrectly considered vegetable mouths. 



But it is not by the whole surface of the root that the 

 absorption of nutriment takes place ; it is the spongioles 

 almost exclusively to which that office is confided : and hence 

 their immense importance in vegetable economy, the absolute 

 necessity of preserving them in transplantation, and the certain 

 death that often follows their destruction. This has been 

 proved in the following manner, by Senebier : — He took a 

 radish, and placed it in such a position that the extremity 

 only of the root was plunged in water : it remained fresh 

 several days. He then bent back the root, so that its extremity 

 was curved up to the leaves : he plunged the bent part in 

 water, and the plant withered soon ; but it recovered its 

 foi'mer freshness upon relaxing the curvature, and again 

 plunging the extremity of the root into the water. 



This explains why forest trees, with very dense umbrageous 

 heads, do not perish of drought in hot summers or dry situa- 

 tions, when the earth often becomes mere dust for a consider- 

 able distance from their trunk, in consequence of their foliage 

 turning off the rain : the fact is obviously that the roots near 

 the stem are inactive, and have little or nothing to do as pre- 

 servatives of life except by acting as conduits. Mobile the func- 

 tions of absorption go on through the spongioles, which, being 

 at the extremities of the roots, are placed beyond the influence 



