458 BOTANICAL GAZETTE [DECEMBER 
(fig. 26). A lumen develops in the midst of the 4 cells, which canal 
becomes the cavity for resin secretion. Usually the 4 cells now 
divide obliquely with new planes of division parallel to the walls of 
the duct, so that the duct becomes lined with 2 layers of cells 
(figs. 27, 28). A consequent cleavage at right angles to the walls 
of the duct gives rise to 8 cells immediately lining the duct (figs. 29, 
30). This ring of ducts in the cortex, just outside the endo- 
dermis, is the usual complement of ducts for the root. As the root 
grows, however, room is made between the older ducts and new ones 
are formed. The resin ducts of the root are continuous from the 
basal region to the junction of the root with the stem. These ducts 
are somewhat more undulatory than are the tracheids. At times 
there is evidence of the fusion of 2 ducts, but this is merely due 
to a breaking down of internal processes from the cells surrounding 
the lumen rather than an anastomosis. 
An examination of seedlings of 2 mm. or over shows in the 
hypocotyl 2 concentric series of resin canals, the outer series con- 
tinuous down through the entire root system, and the inner merely 
potential in the younger seedlings. The 2 series are connected by 
radial canals between the longitudinal lumina of the series and by 
transverse canals between consecutive longitudinal canals of the 
same ring (fig. 31). Moreover, the inner series is capable of ventral 
extension in roots of one year or over, so that they extend down and 
around the median enlargement of the root. At this place they 
all anastomose in a common center (fig. 14). 
This type of concentric rings with radial anastomoses corre- 
sponds to observations made by Catvert and Boop1e (2) for 
Manihot Glaziovii, but is the reverse of Ltoyp’s (11) observations 
on Parthenium argentatum. 
The ducts in the stem consist of 2 separate systems. These 
systems have similar origin and structure, but different location. 
One series is found in the pith opposite the wood of the bundles, 
while the other series occurs in the cortex opposite the interfas- 
cicular region, almost within the interstices between the phloem 0 
the bundles (fig. 25). These ducts arise somewhat earlier than 
those of the root and apparently are not connected with those of 
the root system in any way. They are continuous throughout the 
