2IO Coiiard — Fasciation in 



all exactly as in the normal stem (Compare Fig. 2). The 

 pith (Med.) forms a ring separating these from the anomalous 

 structures, consisting of internal phlcem of the internal or 

 anomalous system (/. ///.), xylem of the internal system (.vr.), 

 cambium (ar.), normal phloem of the internal system {ph.), 

 bast fibre ring {b./-), bundle sheath [b. s.), cortex {co.), epi- 

 dermis {cp.), and finally the internal cavity (Compare Fig. i). 



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 wav)' 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, i. c, 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 



