227 
the Sporophylls of the Cycadaceae. 
structure, both the centrifugal and centripetal xylem having 
each its distinct group of protoxylem. Higher up in the 
sterile portion these bundles split up into a larger number, 
some of which are partially concentric in structure like those 
in the female sporophyll of Encephalartos. 
Zamia muricata, Willd. 
Male Sporophyll. There are three very small bundles in 
the stalk, with the usual structure, the two outer ones of 
which have a sidelong position. But at a certain level there 
occur in close proximity to two of these the rudiments of 
a bundle lying obliquely towards the ventral side of the 
normal bundle ; in one case the rudimentary bundle appears 
to have a mesarch structure, a minute protoxylem -group 
intervening between the reduced phloem and two rather 
scattered tracheides. In the sterile portion many of the 
bundles exhibit a structure intermediate between mesarch 
and endarch, tracheides occurring at the sides of the proto- 
xylem of which it is not easy to say whether they belong 
to the centrifugal or centripetal portion of the xylem ; in 
the same region are other bundles with a definite mesarch 
structure, some of which have no centrifugal xylem at all. 
Zamia Lindeni, Regel. 
Male Sporophyll. In the stalk is a short row of four 
bundles which are normal in every respect (Fig. 21). In the 
sterile portion are a great number of bundles orientated in 
every direction and with the usual structure. 
Barren Sporophyll. The smaller compactly-arranged barren 
sporophylls at the base of the male cone, which are similar 
in conformation to the fertile organs, present a very interest- 
ing structure. The bundles in the stalk, sometimes one, 
sometimes several in a row, are all more or less to be inter- 
preted as having a partially concentric structure ; in some 
