77 
By repeated division phloem cells are cut off from these 
dividing; cells on the outer side and xvlem on the inner side 
(Fig. 2B). This cambium continues to grow to a certain stage 
when it, too, loses its power of further division and another set 
of new cambiums is formed out in the inner cortex in a similar 
manner to that described above. This is repeated continually so 
that successive rings of vascular bundles separated by thin-walled 
cortical tissue are produced (Fig. IB). 
Short medullary rays run between the collateral bundles but 
these are only the length of the xylern and rarely any longer. 
They do not run through the cortical tissue and connect with the 
medullary rays of the next ring. The walls of the medullary rays 
are pitted (Fig. IC). Pits are often found in the Avails of the 
cortical and the pith cells as Avell as in the medullary rays. Vis- 
cum, another member of the family, also has cortical cells Avith 
pitted walls through which there is protoplasmic connection be- 
tween adjacent cells. 
Mucilage canals traverse stems, roots, and leaves. They are 
formed by breaking down of long rows of cells. In the Awmng 
stem there is one canal in the pith. As the stem grows older more 
of these appear in the pith and in the inner cortex. When new 
layers of cambium are formed in the cortex these are always out- 
side the mucilage canals so that canals are found in the cortical 
tissue between the successive rows of bundles. A canal less 
definite in structure runs along the posterior side of the bundle 
of the leaf. 
This peculiarity m the internal structure of the stem is also 
responsible for the strange macroscopic appearance of the 
Christmas Tree 
The young branch is at first upright, but as it increases in 
thickness it takes on a doAvmvard curve until the angle becomes 
too steep, when it ceases growth and another branch further back 
takes its place and continues the growth until it, too, becomes too 
steeply curved, when another branch takes its place. The portion 
of the branch below the end and the new main branch generally 
dies back. This strange mode of groAvtb is responsible for the 
characteristic rugged appearance of Nuytsia. No such curvature 
is found before secondary growth has taken place and curvature 
is not due to a more rapid groAYth on the upper side of the stem. 
Branches of three or four years’ growth because of their peculiar 
internal structure are very easily bent under comparatively light 
pressure,, and the weight of the leaves and blossoms (that of the 
latter being very considerable) causes the gradual downward cur- 
vature. 
The secondary growth of the root is of essentially the same 
character as that of the stem, though differing a little because of 
