528 Worsdell. — Observations on the Vascular 
internodes before entering the sporangium-bearing scale. 
About two-thirds of the way outward in the cortex this 
bundle divides into two ; a small bundle branches off and, 
turning on itself, passes slightly upwards (Fig. 1) so as to lie 
just above its parent-bundle, and with reversed orientation 
of its parts (Fig. 2). (This, therefore; is different from what 
occurs, according to Strasburger 1 in A. brasiliana , A. Rich., 
and A. excelsa , R. Br., where the bundle does not divide until 
it enters the scale, but agrees with his observations of what 
takes place in A. Cunn inghamii, Sw.). During this transition 
the two bundles appear occasionally so fused with one another 
that the structure resembles that of a concentric bundle. The 
smaller bundle has about three layers of secondary xylem 
and is about three rows of tracheides in width : the large 
lower bundle has about four layers of secondary wood and 
is about four rows in width. There is naturally some variation 
in the point of branching, this taking place lower down in 
some cases than in others. 
Immediately after this vertical branching, the lower (larger) 
bundle divides in the horizontal plane into three, of which 
the two lateral pass off somewhat to the right and left of the 
median one (Fig. 3). As soon as the bundles have entered the 
base of the scale, the upper one gives off a branch on either 
side, each of which passes across and takes up a position 
between the median and a lateral bundle of the lower group, 
so that this latter now consists of five bundles (Figs. 4 & 5). 
But, in some cases, only one such bundle may be given off. 
In other cases one of the lateral bundles of the lower group 
may divide, and, at the same time, a branch from the 
upper bundle may be given off and join the branch so 
formed. The upper bundle divides again into two which 
remain side by side (Fig. 5), and the outside bundle on each 
side of the lower group divides into two, of which the outer- 
most revolves on its axis and comes to lie, with inverted 
orientation, on the same side as the upper bundle, so that 
there are now four bundles on this side and about five on the 
1 Strasburger: Die Angiospermen und die Gymnospermen ; 1879. 
