244 Dr. Schleiden on the Anatomico-physiological 



plants with closed vascular bundles the arch-formed course 

 peculiar to the vascular bundles of the peripherical parts, which 

 is easily made evident by 

 a diagram of the construc- 

 tion of such a stem, as 

 in the annexed Figure, 

 where the dotted lines re- 

 present the limits of the 

 mass (the hollow cone) be- 

 longing to each interfolial 

 part, and the arrow de- 

 notes the direction which 

 does not exactly corre- 

 spond to the direction from 

 within outwards in a deve- 

 loped stem, but combines 

 this and the other direc- 

 tion from above downwards, each cone being at the same 

 time a newly deposited part directed outwardly and a new 

 internode added superiorly. Now^ every leaf [a) has originally 

 its position on the apex {ai) of the hollow cone, which ori- 

 ginated contemporaneously with it, and in which those vas- 

 cular bundles belonging to the leaves naturally proceed ob- 

 liquely from the periphery inwards and upwards to the leaf, and 

 consequently to the axis of the stem (.r). From this position 

 the leaf is now in consequence of the continued formation gra- 

 dually pushed towards the periphery, which course its vascular 

 bundles must follow, as they perforate all the succeeding cones 

 just as a branch of one of our forest trees breaks through the 

 subsequent annual zones ; whence it results that the second 

 portion of the arc is formed from within obliquely outwards 

 and upwards. Now whether the arc is longer or shorter, or 

 what is the same thing, more or less curved, depends princi- 

 pally on the shape of the recently superposed cone, i. e. on 

 the terminal shoot. The more acute the terminal bud the 

 longer the curve, as in most of the Palms ; and the flatter it is 

 the shorter and more curved is the arc, as in most Monoco- 

 tyledonous Rhizomes. 



It is^ however, evident that we dare not make use of the 



