234 Salisbury —The Extra-floral Nectaries of the 
The lip consists of slightly thickened cells covered by an epidermis of 
radially elongated elements and strongly thickened external walls, whilst 
near the nectary its cells are sometimes divided tangentially. The median 
dorsal leaf-trace accompanied by a sclerenchyma sheath, which is a con- 
tinuation of that which surrounds the stele of the stem, passes close beneath 
the nectary. 
Opposite the nectary the sclerenchyma sheath is pierced, and through 
this opening there passes from the bundle to the nectary a band of small- 
celled tissue with dense contents, large nuclei, and strongly thickened walls, 
which latter are deeply pitted (PI. XVI, Fig. 2, s p). 
This, which we may term the epithem tissue, broadens out as the 
nectary is approached, and on reaching the latter forms an almost con- 
tinuous layer beneath the basal cells. Around this epithem strand is large- 
Fig. 5. Diagram of gland of Polygonum cilinodum. Scl. sclerotic tissue ; ep. small-celled 
epithem. 
celled parenchyma which in a transverse section appears as two groups 
to right and left of the small-celled tissue (PI. XVI, Fig. 2, l p ). 
The secretory trichomes themselves are in this species much more 
complex than in any of the others examined ; this is due to increased 
division, and applies not only to the secretory but also to the stalk and 
basal regions. 
The glandular head shows both radial and transverse division, the 
latter may take place in some or all of its cells. 
The petiole of this species is rounded in transverse section with 
a slight concavity above (PL XVI, Fig. 9). It contains six bundles, the five 
forming the dorsal arc are of nearly equal size, whilst the ventral bundle is 
larger. A noticeable feature in this species is its fringed ochrea. The 
hairs which arise from the base of the latter are directed downwards and 
