252 Browne . — The Anatomy of the 
trace, and is formed by the prolongation and condensation of the product of 
fusion of all or several of the strands of the cone. In E. giganteum the acumen 
is usually penetrated by a single, very narrow strand which widens out 
slightly higher up. In Cone C two very narrow strands, the middle ones of 
the longitudinal reconstruction, pass into the acumen. In this species the 
other strands of the cone pass out into sporangiophores of the uppermost 
whorl. 
At its base the acumen rests upon a rounded, lobed, parenchymatous 
cushion, apparently representing the concrescent primordia of incompletely 
developed sporangiophores. These lobes (or sporangiophores) are adnate by 
their upper surfaces to the acumen. In E. giganteum some of the lobes 
commonly bear on their lower surface small sporangia, closely fitted into 
and dovetailing with those borne on the upper side of the obliquely 
upwardly directed sporangiophores of the highest whorl. The sporangio- 
phores of this whorl are short-stalked structures, partially concrescent with 
one another, and intermediate in appearance between the other sporangio- 
phores and the adnate lobes. In E. hyemale as a rule the sporangia of the 
uppermost whorl of sporangiophores are closely fitted into the parenchy- 
matous cushion at the base of the acumen, and the lobes of the cushion 
usually bear no sporangia. But in Cone D one of the sporangiophores of the 
highest whorl was inserted rather lower down than the others, and above it 
a small sporangium was produced on the lower surface of one of the lobes 
adnate to the base of the acumen. 
VI. The Region transitional from Fertile Stem to Cone. 
A. Description in E. hyemale. 
As we reach the level of the insertion of the annulus in E. hyemale 
most of the strands of the internode above the uppermost whorl of leaves 
become united. Slightly higher up numerous fresh meshes arise. In none 
of the species that I have studied are the fusion of the strands at or below, 
and their branching above, the insertion of the annulus so marked a feature 
as in E. hyemale. Relatively few meshes persist through this level, and the 
nodal appearance of the region is very striking in all the longitudinal 
reconstructions of the axial stele (cf. Text-figs. 2, 3, and 4). In all cases 
more meshes are closed at or near the insertion of the annulus than arise 
above it. Comparatively wide sweeps of xylem extending through the whole 
of the internode between the annulus and the basal whorl of sporangiophores 
are characteristic of this species. Altogether the development of xylem in 
this region is relatively greater than in any other species the anatomy of 
which is known to us. I think, however, that the fact that a compara- 
tively large number of meshes are closed in the neighbourhood of the 
annulus in this species is partly due to the narrowness of the stele at the 
