THE HIGHER CRYPTOGAMIA. 355 



fourth being near to the second, and obliquely opposite to the 

 third. The primary cell of the fifth root lies near the first, 

 exactly opposite to the third. The sixth originates near the 

 second obliquely opposite to the fifth. The places of origin of 

 the roots of the first year as well as of all the successive 

 periods of vegetation consequently all lie in a plane 

 passing through the indentation of the underside and the 

 terminal bud of the stem. The roots are developed in 

 ascending order. Each new root originates somewhat 

 higher up, and farther from the longitudinal axis of the 

 stem than the second preceding one, i. e., its next neigh- 

 bour underneath. The points of origin of the roots of the 

 first vegetative period form together an arc slightly convex 

 below (PI. XLIX, figs. 1, l h ). During the development 

 and the penetration through the bark of the roots sub- 

 sequent to the third root, the former are compelled (like 

 the third root itself), to bend downwards towards the 

 furrow* of the stem, in order to avoid the vascular bundles 

 of the preceding roots. If the third root diverges to the 

 right of the longitudinal axis of the elliptical transverse 

 section of the stem, then the fourth will turn to the left of 

 it, the fifth also to the left, the sixth to the right, and so 

 forth. Each new root converges at a more acute angle 

 to the small horizontal axis of the stem ; the last roots of 

 the first year are almost parallel to that axis and to the 

 furrow of the underside of the stem (PI. XLVIII, fig. 5). 



The roots as they break through the bark bend sharply 

 downwards, and appear on the underside of the stem 

 arranged in two rows almost parallel to the indentation of 

 the latter. The locus of the points of penetration of the 

 roots may be considered as forming an elongated ellipse. f 

 The roots which are nearest to the centre of the stem and 

 the lowest down, are the oldest, those which spring from 

 the wide lateral margins and are the highest up, are the 

 youngest. The vascular bundles of the third and following 

 roots, which are excentrical like those of the first and 

 second, are brought near to that side of the root which is 

 turned towards the furrow of the stem ; the excentricity 



* This furrow becomes continually more and more clearly defined. 

 f Von Mohl, ' Vermischte Schriften,' p. 137. 



