KINGSLEY: SPLITTING OF RHIZOME OF DELPHINIUM 315 
There is, then, complete correspondence in the method of splitting 
in rhizome and root. 
In general it can be said that originally in the young seedling, 
rhizome and root must have been continuous and undivided. As 
secondary thickening, accompanied by abnormal changes in central 
and peripheral tissues, took place, necrosis occurred in the center 
and to a slight extent on the outside. Longitudinal sections show 
that the central disintegration is very irregular, being a wide region 
narrowing down at each end to a small neck which opens into 
another larger cavity, etc. Jost claims that there is a corres- 
pondence between the leaf position and the bundle courses, and 
between the bundle courses and the splitting. So far as this 
material can be examined, there seem to be no remaining leaf 
traces to affect the bundle course, which is apparently straight 
down through the rhizome and continued in the root. But as 
has been mentioned before, the columns always contain finally 
a single bundle strand. This column must necessarily continue 
its own existence independently, and it is apparently quite capable 
of doing so, having, as it does, an active outer cambium zone, 
which in successive years may circle farther and farther around 
inside of the limiting endodermal layer, perhaps finally forming, 
with the meristematic parenchyma on the inside, a complete ring 
around the column. No material of the age I have, shows such 
a complete ring, but in the four year old stage we have a very 
close approach to this state. 
To summarize briefly the order of splitting for the rhizome, 
which is followed exactly in the root, we can say: 
1. There is regular primary shoot structure. 
2. The cambium ring produces annually some xylem and 
phloem tissue, but much parenchyma in the normal place of these 
elements. An endodermis ring appears between the outermost 
spongy cortex and the regularly formed outer parenchyma. 
Periderm surrounds the whole. 
3. In the third year, an inner endodermislike ring cuts off the 
primary xylem and parenchyma enclosing a necrotic pith, from 
the rest of the tissues. 
4. The outer endodermis pushes down between the xylem 
masses, joins the inner ring of like structure, making one con- 
