262 
Macfarlane. — Observations on 
the solid midrib above corresponds to the tendriliform midrib 
of Nepenthes. Now, if a section of a pitchered Sarracenia 
leaf be made a little higher than the pitcher bottom, and 
microscopically examined, one sees (Fig. 12 ) that a cylinder 
of bundles surrounds the cavity, but that the wing or 
dorsal flap has two rows of bundles parallel to, and with 
their xylem facing each other. This can only be explained 
on the supposition that we have here to deal with opposite 
leaf lobes whose faces are not only applied to each other but 
organically fused. After noticing this I turned to the leaf 
of Iris for verification, since it has long been known to exhibit 
such a condition. The exact agreement of the two in fun- 
damental structure will be demonstrated by reference to Figs. 
12 and 13. The only slight difference is that while Iris, 
like most Monocotyledons, has a feeble, practically unrecog- 
nisable midrib, in our genus it is very large. The tubular 
pitcher therefore is the hollowed-out upper part of the midrib, 
and the dorsal flap growing out from it results from fusion 
of two leaflets. 
The lid in the different species varies considerably. In vS\ 
flava , S. Drummondii , and .S'. purpurea, one strong median 
ventral and two feebler ventro-lateral bundles, after traversing 
the pitcher, tend to converge without fusing, while they are 
joined by transverse branches. These, along with still feebler 
bundles which join them after circling round the orifice, all give 
off lateral veins into the expanded lateral lobes of the lid. 
In 5 . rubra five bundles of the pitcher run straight up into 
the lid, the two lateral ones being joined by small bundles 
from round the orifice. In 5 . variolaris and S.psittacma the 
median ventral bundle is very strong while two to four feeble 
lateral bundles join it. In all cases then the pitcher bundles 
tend more or less to recompact themselves, and after entering 
the base of the lid give off radiating branches. I think we 
may therefore rightly regard the lateral lobes of the lid as 
a pair of leaflets given off from a midrib which does not, as 
in Nepenthes, pass off into a filiform process, but is continued 
upward between the lobes as an expanded median plate. 
