Coprosma Baueri. 21 



with the outer air. Stomata are of usual type, surrounded by the 

 ordinary epidermal cells, which have not the wavy outline common 

 to their class. The lower epidermis is of a single layer of minute 

 rounded-oval cells, raised into short bluntly conical points on their 

 free surfaces (fig. 3). Numerous unicellular hairs coat this lower 

 leaf surface, most of which spring from an inflated base (fig. 3), and 

 sometimes from a pear-shaped cell, larger than the epidermal cells 

 Among which it is inserted. 



11 The Leaf Pits. (Fig. 1). 



In transverse section the pits present various irregular shapes, 

 and widen rapidly from their openings. In common with other por- 

 tions of the lower epidermis, these pits are beset with numerous 

 unicellular nucleated and non-nucleated hairs. Each pit is lined 

 with epidermal cells, clothed outwardly with cutin, and set with 

 the longitudinal axis at right angles to the surface. Though the 

 spaces in the spongy parenchyma may only be separated from the 

 outer air by two layers of cells, no stomata have been found in these 

 depressions. 



III. The Veins. (Fig. 1.) 



In transverse section the midrib presents an upper epidermis of 

 a single layer of cells, resembling those of the outer layer in the 

 blade. Beneath this is a mass of cortical cells, most thickly de- 

 veloped on the lower surface, and enclosing a vascular bundle, of 

 which the xylem elements form the upper, and the phloem elements 

 the lower, portion of the bundle, as is usual in dicotyledonous leaves. 

 A well marked pericycle surrounds the whole, its cells blending into 

 the mass of cortical cells on the upper margin. In smaller veins 

 the bundle sheath is formed of large cells, whose outer walls are 

 considerably thickened, and when the vein is cut at right angles the 

 sheath resembles a minute necklace. The vessels of the xylem are 

 mainly spirally strengthened, and those of the protoxylem are ex- 

 ceedingly slender and delicate. 



IV. The Stem. (Figs. 5 and 6.) 



In transverse section, fig. 5, the stem is peculiar for the depth 

 of the bast layer, and for the way in which it gradually merges into 

 the phelloderm of the cortex. The only difference in transverse sec- 

 tion between phloem and phelloderm is the direction of the longi- 

 tudinal axis in their cells, in the former running radially, in the 

 latter circumferentially. The phellogen shows clearly, and there Is 

 a layer of empty cells below the dead cork. 



In longitudinal section, (fig. 6), the elements of bast and wood are 

 particularly interesting, especially in reference to the xylem and phloem 

 parenchyma, which are very well represented. The wood parenchyma is 

 exactly of the type illustrated by Strasburger (11), as are also the 

 tracheides, with narrow oblique bordered pits, figured by that author 

 under the term fibre tracheides. In tangential section the medullary rays 



