1 8 Plowman . — The Comparative Anatomy and 
At this point it is proper to call attention to the fact that evidence 
of cambial activity has been observed in the internodal bundles of 
practically all the examples of the Cyperaceae which have been studied. 
Fig. 6 is taken from a section near the base of an internode of .S. cyperinas . 
The cambial nature of the zone between xylem and phloem in this 
instance can scarcely be questioned, as it comes well within the definition 
of ‘cambium/ as originally laid down by De Bary (12). We certainly 
do not have here a ‘ closed 5 collateral bundle such as is commonly 
represented as being the exclusive type among the Monocotyledons. Queva 
(38) has demonstrated a similar cambium in Gloriosa, Guillaud (19) 
observed a persistent cambiform tissue in Canna , and Miss Sargant (43) 
cites still other examples. Through the kindness of Dr. Chrysler, the 
writer has been able to examine sections of several grasses, some of 
which show a far more typically developed cambium than has hitherto 
been described in the Monocotyledons. It should be said, however, that 
it happens in certain instances that the xylem and phloem are completely 
separated in the mature bundle by a plate of sclerotic tissue, as shown 
in Fig. 13 of Didichiuni , and as described by De Bary (12) for species 
of Rhapis and Calamus. More or less complete lignification of the 
phloem, such as that observed in Helianthus by Boodle (3), occurs in 
Fuirena and species of Eriophorum. 
We have now to consider the structure of the nodes, and the course 
of the bundles through the stem. A study of the nodal structures 
represented in Figs. 7, 8, 9 from Scirpus cyperimis will make it evident 
that the arrangement of the fibro-vascular elements of the stem is pro- 
foundly disturbed at this point. Moreover, other parts of the structure 
are often specially modified in this region. The medulla is usually 
more compact, if not, indeed, sclerotic ; and it is of less breadth, owing 
to the encroachment of the anastomosing fibro-vascular strands. There 
are no cortical air-spaces, and in the jointed Chlorocyperaceae the as- 
similatory zone is either much reduced at the nodes or is even entirely 
wanting. The longitudinal extent of the nodal plexus varies from less 
than half a millimetre in Didichium and the slender Carices to over 
half a centimetre in Scirpus sylvaticus and large plants of Carex comosa. 
Approaching the node from below, the first indication of a departure 
from the simple internodal condition is seen in the interlacunar bundles 
of the cortex. Here the xylem-elements rapidly increase in number, 
spreading around the phloem in a broad U-shaped mass. The arms 
of the U next become involuted in such a manner as to include a portion 
of phloem on either side of the original phloem, after which the small 
lateral amphivasal strands separate off from the main central narrow 
V-shaped strand thus : 0V0. This stage is represented, though in a 
somewhat complicated form, in Fig. 7. Passing to a slightly higher 
