1884.] 467 [Branner. 
direction of the apex of the phylophore. When in the process of develop- 
ment, a bundle has a frond or spadix formed in connection. with it, it is 
clear that the base of this frond, being left behind by the growth of stem 
and bundle, must at some time become a scar upon the side of the stem, 
and as the developing point of the bundle is always near the apex, the 
bundle will be formed more or less in a line connecting the sear or point 
of branching and the apex of the phylophore which is in the axis of the 
stem. But although the bundle is' formed in this line, it does not follow 
that on the growth of the trunk it will be found in a straight line from 
the scar to the apex. In reality we find the lower extremity of the divis- 
jon as nearly as may be parallel to, and very near the side of the stem. 
This will be better understood from figs. V, VI and VII. 
Let © be the apex of the phylophore at which a bundle branches. In 
the process of growth of the phylophore, the point C will be left behind 
at D, and the growing division of the bundle, pointing always toward the 
centre, will be developed in the direction DC or JI, practically very nearly 
parallel with the side CHD. Now when the apex is far beyond the origi- 
nal point of branching of this bundle, say at A, while the original point 
of C is at B, this part of the bundle that was formed first after the branch- 
ing took place, will still have its original relation to the side of the stem, 
that is, it will be about parallel to it. When the point © is left at E, the 
direction will be still further changed, and will be IK, farther from the 
periphery, and when IK is left far behind it will be in a position like MN 
in figure V. Then again when the point C is left at B (Fig. V) we shall 
have the part IL forming, and thus will the growth of the bundle in length 
gradually approach it to the axis of the stem. Upon its arrival at a suffi- 
ciently advanced stage of development to take its place again, and again 
have a frond developed in connection with it, it will have crossed in its 
course all the bundles that have branched since it branched at © original- 
ly. I would suggest that this development of the fibro-vascular bundles, 
always in the direction of the apex, is due to the light. This apex, at its 
central point, is very pulpy and translucent, while its sides are enveloped 
by the young and growing fronds, which render the parts surrounding the 
centre more or less opaque. 
The outward curve of these bundles is a simple matter. It marks the 
line traversed by the base of the frond from the time it originated at the 
apex of the phylophore until it reached its place on the side of the trunk. 
In figure VII, let © be the centre of the growing part at which the frond 
and bundle connect. Now when the apex has grown to O/, the point C will 
have been left behind at A upon the side of the growing cone, and when 
the apex is at O//”, the point which was originally at © will have taken 
its place at EH upon the side of the stem. In this outward curve, the 
longitudinal growth of the bundle is shown. In figure IX if C be the 
former position of the apex at which a frond was developed, and which 
takes its place later upon the surface of the stem at D, it might be inferred 
that OF were the vertical distance grown by this section of the stem from 
