210 Conard—Fasciation in 
all exactly as in the normal stem (Compare Fig. 2). The 
pith (J/ed.) forms a ring separating these from the anomalous 
structures, consisting of internal phloem of the internal or 
anomalous system (7. f/.), xylem of the internal system (<y.), 
cambium (ca.), normal phloem of the internal system (/.), 
bast fibre ring (4. f), bundle sheath (4. s.), cortex (co.), epi- 
dermis (¢.), and finally the internal cavity (Compare Fig. 1). 
The internal and external systems are in no wise different, 
save that the inner one is more slender and is inversely 
oriented. The internal epidermis bears stomata, nectar glands 
and pedicellate hairs like those of the external epidermis. 
The internal cortex is rich in chlorophyll as is the outer. The 
bundle sheaths of both systems are evident, their cells being 
filled with starch. The bast fibre rings are one or two cells 
deep in both systems. The xylem frequently has large 
tracheids in the cambial region. Both rings of cortex, and 
the common pith have numerous longitudinal milk canals. 
Tracing the two tissue systems to the ring-shaped growing 
apex, we find both merging gradually and equally into the 
circular mass of meristem tissue. Leaf rudiments seem as 
plentiful at the apex on the inner as on the outer surface of 
the tube. The end of the hollow stem is not evenly truncated 
in outline, but has a wavy margin, or, more often, is split on 
one side, so that the stem continues as a plain or wrinkled 
fasciation (Fig. 5). 
Following the hollow in the direction of the parent axis, 
the cavity becomes gradually narrower, until there is only 
room for one or two hairs to lie longitudinally in it. Then 
the faces of the epidermis come into contact, and finally this 
tissue ceases entirely, z. ¢., the cavity is closed. Below this 
point then, we have the internal system reduced to a cylinder 
of fibro-vascular bundles in the center of the pith of a solid 
stem. Proceeding farther toward the root, the cylinder 
breaks up into separate bundles by dwindling away of the 
