222 Worsdell . — The Vascular Structure of 
development as regards the centripetal xylem, which is quite 
small in amount. Nearly all the bundles have three or four 
(one bundle had seven or eight) tracheides of centripetal 
xylem ; these are, however, always faint, rounded, and weakly 
stained compared with those of the centrifugal xylem. In 
the sterile portion the usual structure of this part prevails ; 
some of the centripetal xylem is developed as transfusion- 
tissue which is both lateral and ventral in position. 
Female Sporophyll. Two bundles leave the cylinder of the 
axis of the female cone, and on their way through the cortex 
divide up into a considerable number of bundles, so that in 
the stalk of the sporophyll a row of about nine bundles 
occurs. Though the sporophyll is one of the largest in the 
order (equal in size to that of Encephalartos'), the mega- 
sporangia are not nearly so large as in that genus ; con- 
sequently, the bundles have also a considerably less 
development, and are all regularly orientated. In those 
sporophylls which bear two well-developed sporangia, the one 
or two bundles at either end of the row are larger and have 
better-developed phloem and centrifugal xylem than the 
intermediate ones (Fig. 15). In those with one abortive 
sporangium, the most external bundle of the row on the same 
side of the stalk is scarcely better developed than the rdst. 
In those with both sporangia abortive, the same applies to 
the external bundle on both sides. The bundles of the 
lamina exhibit the ordinary structure (Fig. 1 6). The external 
bundle of the row on one side of the stalk and a branch from 
the bundle next to it bend off in the lamina and pass down to 
supply the sporangium ; each of these divides into three, so 
that six bundles enter the latter (Fig. 17). Of these two 
or three of the smaller ones are perfectly concentric in 
structure. Some of the bundles of the inner portion of the 
integument of the sporangium have also a concentric structure, 
the protoxylem occupying the centre of the bundle and 
enclosed by primary tracheides ; the phloem, however, on the 
ventral side is rudimentary in character; the occurrence of 
these bundles in the integument seems to show that the 
