216 WorsdelL — The Vascular Structure of 
intermediate ones (Figs. 6 and 7). Only in one or two 
bundles are two or three very small centripetal tracheides 
seen. The bundle at either side which supplies the sporangium 
forks just on entering the base of the lamina, one branch 
passing upwards, the other bending off towards the reflexed 
lateral lobe, between which and the stalk the sporangium 
is seated. Before this bundle assumes its downward course 
into the lobe, however, and opposite the place of insertion 
of the sporangium, it gives off a branch which forks : of the 
two bundles thus formed, one enters the sporangium without 
further change, the other, immediately before entering the 
latter, divides into two (Fig. 5). 
The bundles of the lamina are characterized by a great 
reduction in the centrifugal and a corresponding increase 
in the centripetal xylem, so that the two parts are about 
equal in development (Fig. 8). The lamina of a female 
sporophyll at a very young stage was examined ; in this 
is a number of very small bundles, most of which have an 
element or two of centripetal and one or two of centrifugal 
xylem. A few of them have no centripetal xylem besides 
the protoxylem. It is difficult to make out which is primary 
and which secondary centrifugal xylem in some bundles ; 
the smaller elements in connexion with the protoxylem are 
probably primary. The centrifugal and centripetal xylem 
appear to be developed simultaneously. Many of the ele- 
ments of the latter are very small and closely united to the 
protoxylem, two or three together, and would most likely 
have the same spiral thickenings as the latter ; others usually 
single, lie some distance away. 
Scale Leaves and Barren Sporophylls . At the base of the 
peduncle of the male cone are large, narrow, elongated scales, 
consisting of a fleshy central portion, with a wing on either 
side. They contain at the base three bundles which are 
collateral in shape, and possess secondary centrifugal xylem ; 
a tracheide belonging to the centripetal xylem is here and 
there seen. In the upper part of the scale the bundles 
increase to four or six, becoming very much reduced in size, 
