386 West. — A Contribution to the Study of the Marattiaceae. 
central strand fuses with a meristele of the dictyostelic ring (cf. 30 , Plate X, 
Fig. 6). In this way a direct water-channel is formed between a root and 
the next leaf above. 
Two strands only are given off to supply the petiole, but as they pass 
outwards through the cortical region of the stem, they divide into several 
(eight or nine) strands, which, at the base of the petiole, are arranged in 
a typical horseshoe curve (cf. 30 , PL X, Fig. 12). 
The vascular anatomy of the petiole closely resembles that of Kcml- 
fussia and of Danaea , internal accessory strands being found in the region 
of the basal pulvinus of all three genera. 
Also, the manner in which the pinnae obtain their vascular supply 
from the rachis is essentially similar in these three plants. 
4 Marattia. 
The adult sporophyte of Marattia possesses an upright, tuberous, more 
or less conical stem surmounted by a rosette of large pinnate leaves ; the 
remainder of the stem surface is almost entirely covered by the huge leaf- 
bases. Numerous stout adventitious roots anchor the stem to the soil. 
Apart from a passing reference by Holle ( 34 ), the vascular anatomy of 
this genus was first studied by R. Kuhn ( 42 ), who found in the stem 
of comparatively young plants of Marattia fraxinea a peripheral ring of 
anastomosing vascular strands surrounding a single axile bundle ( 1 . c., Taf. 
XVI II and XIX, Fig. 22). In rather older stems of the same species this 
investigator showed that the stelar system was further complicated by the 
appearance of a second zone of anastomosing strands ( 1 . c. 3 Taf. XVIII and 
XIX, Figs. 30-32). His account of the arrangement of the vascular strands 
is rather difficult to follow, but he seems to show that compensation for the 
departure of the leaf-traces from the outer zone of bundles is provided for 
by two strands which leave the inner zone and, passing obliquely outwards, 
help to close up the foliar gap. The central strand likewise gives off two 
branches which assist in closing the gap formed in the inner zone. It will 
be noticed that Kiihn describes for the comparatively young plant of 
Marattia fraxinea a type of stelar structure which is fundamentally similar 
to that of the adult sporophyte of the radial species of Danaea (e. g. Danaea 
nodosa , Sm.). 
Farmer and Hill ( 29 ) gave a brief account of the development of the 
vascular system in the sporeling of this same species of Marattia , and 
showed (1. c., pp. 378-9) that the protostele found at the base of the stem 
of the young sporophyte opens out to form a siphonostele with extremely 
large foliar gaps ( 1 . c., PI. XVII, P'igs. 20 and 21). Sooner or later 
commissural strands of an attenuated form are developed within the 
siphonostele. The earlier leaf-traces are single, but those subsequently 
formed fork once in the stem-cortex ; the dichotomy extends farther 
