258 Browne . — The Anatomy of the 
E. maximum t E. hyemale , and E . giganteum . a certain number of parenchy- 
matous meshes are always closed at or near the level of the annulus. Such 
closure of parenchymatous meshes is of course universal at the nodes 
bearing leaves. The closure of some meshes is characteristic also of the 
nodal regions of the cone, though in species with relatively little xylem 
exceptional nodes occur in which no meshes are closed. We may generalize 
from these facts and say that the closure of parenchymatous meshes occurs 
normally only at or near the nodes, while at the vegetative nodes all the 
meshes are closed. In the light of these facts it will easily be realized that 
the insertion of the annulus on the axis marks the position of a reduced 
node. Further, in all the species the anatomy of which is known to us, 
except E . giganteum , a number of new meshes arise above the insertion of 
the annulus, although the latter is not supplied with traces. It would seem 
that reduction first affected the formation of traces, secondly the formation 
ofi fresh meshes, and lastly the closure of meshes ; for the number of meshes 
formed above the annulus, i. e. above the reduced node, is constantly less, 
usually markedly less, than the number closed below it. As already pointed 
out (Browne ( 1 ), p. 691), the closure and formation of meshes are not con- 
fined respectively to cones showing a decrease or increase in the number of 
members in the lowest whorl of sporangiophores compared with the number 
of leases in the uppermost leafy whorl. These fusions and branchings 
cannot, therefore, be regarded merely as a method of carrying out such an 
increase or decrease in the number of axial appendages, but would seem to 
represent a vestigial nodal character. It might seem strange that in spite 
of the presence of vascular bundles in its annulus E . giganteum is the only 
species in which no fresh parenchymatous meshes arise between the annulus 
and the lowest whorl of sporangiophores. 1 This, however, is readily under- 
stood if the development of sporangia by the annulus be regarded as 
a character recently acquired in the phylogeny. The vascular bundles of 
the annulus would then be a response to the increased need for water, 
brought about by the development of sporangia. This response would, 
however, prove a considerable strain on the xylem-producing capacity of 
the plant in this region. When, as in Cone C, tracheides are actually given 
off from the axis into the annulus it is clear that there will be less xylem 
immediately above this point. Now we have seen that one of the results 
of the reduction of axial xylem at a node of the cone is the failure to 
produce fresh parenchymatous meshes in the internode above. This is 
what I believe has occurred at the ‘annular node’ of E. giganteum ; for 
even when the annular bundles die out without reaching the stele their 
formation imposes a considerable strain on the xylem-producing capacity of 
1 To judge from a single cone of E. variegatum, Schleich, of which I have prepared sections, 
it would seem that in this species no fresh meshes arise above or are closed below the annulus. The 
cone is small and seems to be reduced, but its structure requires further elucidation. 
