254 Browne.—A Second Contribution to our Knowledge of the 
downwards (but much less steeply than do the bundles of the abaxial arc), 
and the two bundles at each end of this series divide again in a plane nearly 
coinciding with a line drawn radially through these bundles (the latter are 
by now arranged nearly back to back, but at a certain distance from the 
bundles of the stem that gave rise to them by division). The resulting 
series of six bundles forms the adaxial arc of the branch stele. Above the 
insertion of these adaxial strands the parenchymatous hump only contains 
the abaxial series open adaxially ; after the adaxial bundles have taken 
their place in the circle of the branch stele no traces remain of the distinc¬ 
tion in origin between the bundles of the arcs. Lower down, at the 
departure of the adaxial strands, there is also no break in the stele of 
the stem, since the bundles of the branch stele arise by the forking of 
bundles, and the inner strands resulting from this forking pursue a course 
vertically downwards. The main stele, which above the departure of the 
abaxial bundles of the branch stele had forty-three bundles, has below their 
departure thirty-eight, a number which is not affected by the departure of 
the adaxial bundles. The relations between the strands of the main stele 
and the vascular system of the larger abortive branch are diagrammatically 
represented in Text-fig. 5. 
The stele of the lower and smaller abortive branch consists, when 
it reaches its greatest development, of six bundles. The two outermost 
bundles of this branch have passed out in their entirety from the main stele, 
while the four adaxial ones arise by the division of the two bundles of the 
central cylinder, and by a second division of two bundles of the series that 
arose by the first division. The planes of these divisions are respectively 
similar to the first and second divisions, giving rise to the adaxial bundles 
of the larger abortive branch. Below the insertion of the two abaxial 
bundles of the smaller branch and by their departure the number of bundles 
in the main stem is reduced to thirty-six. This is also the number of traces 
in the uppermost leaf-whorl, and of the bundles in the internode below it. 
In the smaller abortive branch the vertical distance between the 
insertion of abaxial and adaxial bundles on the main stele is only 980 /x, 
whereas in the larger abortive branch the vertical distance between the 
insertion of these two series of bundles is not less than 9*7 mm., possibly 
considerably more. The distortion of the stem in this region led to the 
breaking and tearing of these tissues, so that it is impossible to determine 
the exact distance between the departure of the abaxial and that of the 
adaxial bundles of the branch from the bundles of the axis. In the diagram 
the smallest possible distance has been adopted. 
In both abortive branches, as we pass downwards in the parenchymatous 
projection, after the entry of the adaxial bundles into the branch stele 
the latter condenses, and the bundles fuse and die out, still running 
obliquely downwards. This occurs before we reach the lower limit of the 
