Radicle and Germcn of Seeds. 120 



occasions a continued increase of the growth of the upper 

 parts of the radicle; and this growth is subsequently aug- 

 mented by the effects of motion, when the germen has risen 

 above the ground. The true sap is therefore necessarily ob- 

 structed in its descent; numerous lateral roots are generated, 

 into which a portion of the descending sap enters. The 

 substance of these roots, like that of the slender horizontal 

 branches, is much less succulent than that of the radicle 

 first emitted, and they are in consequence less obedient to 

 gravitation ; and therefore, meeting less resistance from the 

 superficial soil than from that beneath it, they extend hori- 

 zontally in every direction, growing with most rapidity, and 

 producing the greatest number of ramifications, wherever 

 they find most warmth, and a soil best adapted to nourish 

 the tree. As these horizontal or lateral roots surround the 

 base of the tree on every side, the true sap descending down 

 its bark enters almost exclusively into them, and the first 

 perpendicular root, having executed its office of securing 

 moisture to the plant, whilst young, is thus deprived of 

 proper nutriment, and, ceasing almost wholly to grow, be- 

 comes of no importance to the tree. The tap root of the 

 oak, about which so much has been written, will possibly 

 be adduced as an exception ; but, having attentively exa- 

 mined at least 20,000 trees of this species, many of which 

 had grown in some of the deepest and most favourable soils 

 of England, and never having found a single tree possessing 

 a tap root, I must be allowed to doubt that one ever existed. 



As trees possess the power to turn the upper surfaces of 

 their leaves and the points of their shoots to the light, and 

 their tendrils in any direction to attach themselves to conti- 

 guous objects, it may be suspected that their lateral roots 

 are by some means directed to any soil in their vicinity 

 which is besst calculated to nourish the plant to which they 

 belong; and it is well known that much the greatej part of 

 the roots of an aquatic plant, which has grown in a dry soil, 

 on the margin of a lake or river, have been found to point 

 to the water; whilst those of another species of tree, which 

 thrives best in a dry soil, have been ascertained U take an 



Vol. '25. No. ob. July 1S06. I v pposite 



