OF WOOD IN GENERAL. 



embryonic layer in which it originates is termed the dermdtogen 

 (derma, skin, and genndo, to produce). In the middle of the 

 growing-point is a solid column-like mass of cells which are all 



FIG. 2. Growing-point of stem, showing apical meristem. P, plerome ; 

 R, periblem ; E, dermatogen ; /, rudiment of leaf. (After Leunis and 

 Frank.) 



somewhat elongated in the direction of the elongation of the 

 stem. This is known as the plerome and the central axis of 

 tissues to which it gives rise as the stele (Greek for a column) 



FIG. 3. Terminal bud, showing growing-point of stem, overlapped by 

 rudimentary leaves with buds in their axils, the whole covered by der- 

 matogen. In the centre is the stele to which descend the midribs of the 

 leaves. (After Prantl.) 



(Fig. 3). Between the outer dermatogen and the inner plerome 

 there is a layer, or a series of layers, of cells which undergo 

 division both in planes perpendicular to and in planes parallel to 



