230 Worsdell . — The Vascular Structure of 
a difference in this respect from what occurs in the case of 
if. Loddigesii. The smaller bundle is collateral in structure 
and somewhat curved in shape, with two or three elements 
of centripetal xylem, the other larger one has well-developed 
centrifugal and no centripetal xylem, and is curved inwards 
so as to assume an almost concentric structure ; in the base 
of the sporangium this bundle begins to separate into two, 
as a result of which two almost distinct bundles come to 
lie in close contact, with their xylems facing each other. 
Zamia Fischeri, Miq. 
Female Sporophyll. The arrangement and structure of the 
bundles here is very similar to what obtains in the last plant ; 
a small ventral, inverted bundle also being present. 
Zamia Leiboldii, Miq. 
Female Sporophyll. The sporophyll examined bore three 
megasporangia (Fig. 25); as a consequence of this the 
arrangement and structure of the bundles in the stalk are 
somewhat modified to suit this abnormality. On the side 
on which the two sporangia occur is a bundle much larger 
than is usually the case, and close to it another bundle 
almost or quite as large, but lying somewhat obliquely and 
with inverted orientation. The bundle at the other side of 
the sporophyll is very much smaller, corresponding more in 
size to the bundles supplying the sporangia in previous 
species. At a slightly higher level the inverted bundle on 
the side of the two sporangia turns on its axis and becomes 
united laterally, in the normal position, with the adjacent 
bundle, so as to form a single exceptionally large bundle, 
considerably elongated in the tangential direction, and with 
very well developed centrifugal but no centripetal xylem. 
The unusual size of this bundle is obviously correlated with 
the extra sporangium attached to that side of the sporophyll. 
