( Para Rubber Tree): Bud- Scales serving as Nectaries . 221 
leaf, or even three at this point. Occasionally the first pair of leaves 
may be vestigial, or only one of them fully developed. 
If the plumule be fatally injured then the bud in the axil of one 
of the cotyledons develops into a shoot, bearing first three to four reduced 
leaves apparently without nectaries, before the true foliage leaves appear ; 
sometimes the buds in both axils so sprout. The shoot arising from 
the axillary bud of the cotyledon simulates that derived from the plumule, 
but in the one case the length of stem produced before the foliage leaves 
are emitted is really composed of several internodes, the nodes being 
occupied by inconspicuous scale-leaves ; while in the other it consists 
of one internode only, the epicotyl. 
Unfortunately my notes do not connect the seedling with the sapling- 
stage, so as to see when the nectariferous scales first arise. This is 
probably at the second period of foliation. They apparently do not 
appear in the seedling, but rather later in the development of the plant. 
Structure of the individual bud-scales. The structure of the non- 
nectariferous scales requires little description. A glance at Fig. 4 s f 
shows their size and shape. They are each accompanied by a pair of 
lateral bodies — stipules. In the mature or sprouting bud they are brown 
dead objects. 
The nectariferous scales are fairly long, often bent structures and 
somewhat circular in transverse section ; they project from the stem at 
right angles or with a downward inclination. Each bears at its apex three 
minute points, the sole remains of the leaflets. Their upper convex surface 
is covered with yellow honey-secreting tissue, and has often a median 
longitudinal groove. In the lower and middle scales the whole length 
of the upper surface is glandular. In the upper scales the glandular 
portion tends to recede from the proximal part, and in the uppermost 
one it is confined to the apex (Fig. 6 ne). 
From a structural point of view the nectar-secreting tissue of plants 
can be divided into two classes 1 , viz. (1) that consisting of small epidermal 
cells of the usual shape with thin hardly cuticularized outer walls, over- 
lying a mass of closely packed cells full of contents, and secretory in 
function, and (2) that in which the epidermis itself assumes the form 
of a secretory epithelium with greatly thickened cuticle. In the first 
class the nectar reaches the surface by passing through the thin walls, 
while in the second class it escapes by bursting the cuticle. 
The extra-floral nectaries of Hevea brasiliensis present a modification 
of the second type of structure, in that many of the original epithelial 
cells become divided in the mature nectary by tangential walls into two 
or three daughter-cells. That is, in the immature state the epidermis 
1 Bonnier, Les nectaires, £tude critique, anatomique et physiologique, Ann. d. Sci. Nat., 
6 e ser., T. viii, 1879, P* 
