335 
clusions may be reached where more accurate methods are 
employed. 
Bower (3) remarks that ,,frem a theoretical point of view 
the existence of cauline vascular tracts is important, for it accen- 
tuates the axis as something more than a mere basis for insertion 
of leaves.” Bundles which are unmistakably cauline do occur 
in the Marattiaceae (commissural strands), but these structures 
arise late in the ontogeny (in Danaea alata after the develop- 
ment of the sixth leaf). Before this time there is no real stele 
(West 41 and 42). The cauline bundle is here a secon- 
dary structure, and this fact establishes the stem as a secon- 
dary derivative of leaves and roots. 
De Bary (1) states that in the young seedlings of all the 
investigated forms of fern-like plants, the bundle system of 
the stem is a sympodium of leaf traces. 
The “pericaulom” of Potonié (26) and the ideas of Del- 
pino are the morphological expression of these phytonic views. 
Schoute is of the opinion (28) ,,daf diese Theorie sich noch 
nicht über den Rang eines genialen Gedankens erhoben hat, 
und da von einer wissenschaftlichen Begründung derselben 
auch nicht die leisesten Spuren vorhanden sind; deshalb ist 
von dieser Seite auch kaum ein ernsthafter Angriff auf die 
Stelartheorie zu befürchten”. In this connection it will be of 
some interest to cite Campbell (9) “The theory that there is 
a special stele belonging to the stem, of which the leaf traces 
and the root traces are subsidiary structures, is not borne out 
by a detailed study of the evolution of the vascular system in 
either the Marattiaceae or Ophioglossaceae”. 
Medullation and Endodermis. 
Recent investigators emphasize the question of the origin 
of the intrastelar pith and internal endodermis. There is evi- 
dence that these two problems are over-estimated. The vesti- 
gial tracheids in the pith; the internal endodermis may be just 
examples of the anomalous distribution of Caspary layers and 
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