1917] FAUST—RESIN SECRETION i 459 
entire stem, although they are intercepted in certain regions by 
processes from the lining cells, as shown in fig. 35. The origin of 
both these systems in the stem is schizogenous and follows the 
Same sequence of development as outlined for the duct system of 
the root. Hotm (7), working on the anatomy of Solidago odora 
(pp. 252-254), quotes VAN TIEGHEM as saying that resin ducts 
have only been observed in the cortex (primary) “in certain species 
of Solidago, including Kleinia; otherwise these ducts are frequent 
in the pith and in the secondary tissues.”’ The two series of ducts in 
the stem of B. sagittata indicate a composite type of duct anatomy, 
in that they supply a duct system in the primary cortex, hitherto 
observed only in species of Solidago, and in addition supply the 
usual system of the pith. These ducts, too, are subsequent to resin 
formation in the stem. 
The resin ducts of the leaf are merely upward prolongations of 
the stem systems, corresponding to the bundle trace relationships 
already indicated.. For each bundle in the leaf there are two canals, 
one occurring on the upper side of the leaf and the other one on the 
lower side opposite the hadrome elements. DEBARy (4) gave a 
very complete table of the duct systems as far as they had been 
worked out in his day, VILLUEMIN (23) has studied it in certain 
species, and Cot (3) has added to the knowledge of the subject, but 
a thorough revision of the literature needs to be made in order 
to bring the knowledge up to date. 
Since VAN TIEGHEM prepared his schematic outline for types 
of resin duct distribution in the stems of Compositae, at least 
two new types have been observed, namely, the Solidago type 
described by Hotm (7) and the type represented by B. sagittata, 
described in this paper. For this reason it is necessary to recon- 
struct VAN TieGHEM’s scheme to include the more recent 
observations. 
OUTLINE KEY TO SECRETORY PASSAGES IN STEMS OF COMPOSITAE TYPES 
I, Stem containing passages within bundle sheath 
. Passages confined entirely to medullary region. ...Ageratum conyzoides 
B. Passages both within and without bundle stran 
1. Only one medullary passage for each leaf sae bundle 
a) One medullary and one cortical passage 
