ON THE ANATOMY OF CHENOPODIUM ALBUM L. 
However, notwithstanding the comparatively large amount of work 
done on the inner structure of the Chenopodiaceae, the origin of the in- 
traxylary phloem, its relation to the cambium and to the xylem of the 
bundles, remained obscure. It was therefore the primary object of this 
investigation to study the relation of cambial activity to the development 
of the anomalous growth. It was also hoped to extend our knowledge of 
the histology of the vascular tissue, in particular that of the phloem. 
Material and Methods 
The work was begun during the summer of 1919 at Ft. Lewis, Colorado, 
and was completed at the Department of Botany, Cornell University. 
Material taken from the field was studied while fresh. It was found most 
satisfactory to use unstained hand sections for both anatomical and onto- 
genetic studies. This method has an obvious advantage over most modern 
laboratory practice in that it permits the examination of a large amount 
of material in all stages of development with the least expenditure of time. 
But for the purpose of checking results and for use in making photomicro- 
graphs, representative material was killed in Flemming's weaker solution, 
embedded, some in paraffin, some in celloidin, sectioned, and stained in 
the usual manner. 
Anatomy 
A transverse section of a young stem shows between pith and cortex 
a circle of separate bundles — the leaf traces. Their number varies, there 
being even in very young stems as many as twenty. The largest of these 
traces belong to the lower leaves, the smallest to the primordia of the leaves 
near the growing apex. 
These primary leaf-trace bundles are collateral. The phloem in cross 
section is a compact oval or oblong mass of tissue (PI. XVI, A), bounded 
externally and laterally by parenchyma cells which, when still young, con- 
tain chloroplasts. The xylem also is definitely set off from the surrounding 
fundamental tissue. Its first-formed elements are scattered, and only the 
later formed metaxylem and the secondary elements show a definite ar- 
rangement in radial rows. In older sections we notice the development of 
an interfascicular cambium uniting individual leaf-trace bundles of the 
primary cycle, and an extrafascicular cambium from which originates a 
series of collateral bundles and conjunctive tissue. This tissue later ligni- 
fies and, together with the xylem of the bundles, forms a compact woody 
cylinder in which appear embedded small islands of phloem. The origin of 
this intraxylary phloem and of the conjunctive tissue, together with changes 
which take place when the tissues mature, will be discussed under the 
heading "Ontogeny." 
No true secondary phloem develops ; the true phloem remains restricted 
to the bundles in a given cycle. A narrow band of pericycle, sometimes 
