14 BOTANICAL GAZETTE [JANUARY 
in a large amount of heavily pitted wood parenchyma. In the 
cauline strands, on the contrary, the xylem is more vascular and 
the parenchymatous elements are less abundant and thinner- 
walled. A further distinction is the absence of cambial activity 
in the foliar traces, a situation which leads to a less regular arrange- 
ment of the cells than is found in the central strands. In fig. 29 
appears another illustration on a somewhat higher scale of 
magnification than that in fig. 27. The bundle to the right, which 
is a cauline strand, shows distinct evidence of cambial activity — 
such as is figured in STRASBURGER’S Botanische Practicum. On 
the other hand, the foliar strand, which here lies to the left, is 
without cambial activity, as indicated by radial regularity. Fig. 31 
is a partial view of another transverse section, in which a large 
cauline bundle lies on the left, while on the right is another foliar 
bundle, in this case also distinguished by the absence of cambial 
activity. To make clear that cambial activity is really absent in 
the foliar strands of the buttercup in the upper part of their course 
in the cylinder of the axis, several figures under considerable 
magnification have been introduced. Fig. 28 shows a foliar strand 
under a moderately high magnification. It is clear that cambial 
activity is absent here, since there are no regularly radially arranged 
rows of cells intervening between xylem and phloem as is the case 
with the stem bundles. Moreover, the less woody organization 
of the xylem is a further consequence of this absence of cambial 
increments. Fig. 30 shows another foliar bundle in the stem under 
somewhat higher magnification. The absence of cambial growth 
is here still clearer. Fig. 32 shows a still more enlarged view of 
one of the leaf traces in the stem, and the absence of any evidence 
of secondary activity is apparent. 
It is obvious that in the buttercup, precisely as in the sunflower 
and to a less degree in the aster, there is a distinct and striking 
intermission of cambial activity in those fibrovascular strands in 
the stem which have entered from the leaves. In the case of 
Aster attention has been called to the absence of secondary additions 
of the xylem in the case of species in which the root hairs are 
indefinitely persistent. The root of the buttercup, as has long 
been known, is without secondary accretions to the wood. Fig. 33 
