ON THE ANATOMY OF CHENOPODIUM ALBUM L. 
different parts of the ring are found in different stages of development. 
This condition results in the formation of an undulate circle of cambium. 
In this cambium, cell division takes place only centripetally, resulting in the 
formation of a cylinder of tissue consisting of alternate radial segments of 
xylem and of conjunctive tissue. The cells of this secondary xylem, the 
large vessels in particular, are arranged in radial rows, differing therein 
from the primary tissue in which the elements are without any definite 
arrangement. 
After a limited period of activity, certain areas in the cambium, chiefly 
opposite the large primary bundles, undergo a change of function. One 
or two cambium cells divide rapidly in different planes forming from two 
or three to ten cells (fig. 2,A,B;F\. XVII, E, F). 
Fig. 3. Chenopodium album: Transverse section of stem showing mature phloem group. 
The appearance of the new cambium segment above the group is belated. The cambium 
at either side of the phloem group has divided very actively and has thus caused the phloem 
to be completely embedded in xylem. (C, cambium; F, fibers; Ph, phloem; s.x., secondary 
xylem.) 
These cells become the phloem of the just-formed vascular ring. We thus 
have a ring of xylem with segments of parenchymatous conjunctive tissue 
with a number of separated phloem strands on the outside. Occasionally 
the portions of cambium behaving in this manner are not used up in this 
process but may form a small amount of xylem toward the inside after the 
completion of phloem formation. These segments of cambium disappear. 
