6gS Browne . — Contributions to our Know ledge of the 
respect, however, the cone varies much more than the stem, for a portion 
of the band of xylem may be continued upwards through the greater 
part or the whole of the internode, or it may break up relatively near the 
departure of the traces. 
Thus the anatomy of the cone supports the view that the sporangio- 
phores of Equisetum are whole appendages. On the other hand, the 
anatomy of the cone of Palaeostachya and Calamostachys seems to show 
that in these genera the sporangiophores and bracts are lobes of a leaf 
(Hickling, 1 and 2 ). This is a very fundamental difference, and it would 
seem that these genera do not lie at all near the Equisetal line of descent. 
The anatomical evidence is at present insufficient to decide whether the 
sporangiophores of Archaeocalamites were lobes, as were those of Calamo- 
stachys , or whole appendages, as those of Equisetum seem to be. The 
latter view seems to me the more natural. The bracts found at irregular 
intervals in the cone of Archaeocalamites , which I was formerly inclined to 
regard as indications of sterilization of fertile appendages (Browne, p. 17), 
would seem more probably to be reduced vegetative leaves, and their 
occurrence in the relatively ancient Archaeocalamites might be a primitive 
character, indicating want of definition of the strobilus. 
The parenchymatous meshes found in the cone, like those in the 
vegetative internodes of Equisetum , do not, except at the reduced or 
immature apex of the cone, originate immediately above the traces. Thus 
they are not foliar gaps as defined by Jeffrey. Speaking of the tracts 
of parenchyma of the internode of the stem of Equisetum this author says, 
4 They lack, however, one important feature of foliar gaps, for they do 
not occur immediately above the traces , as should be the case with true foliar 
gaps. All other foliar gaps with which we are acquainted show this feature ’ 1 
(Jeffrey (2), p. 252). If this definition of a foliar gap is to be applied in all 
cases, the tracts of parenchyma above the traces of certain recent Osmunda- 
ceae are not foliar gaps. Sinnott, seeking to defend Jeffrey’s view that the 
traces of siphonostelic and dictyostelic Pteropsida always leave gaps, claims 
that when in recent Osmundaceae a trace appears to leave no gap in the 
wood at its departure the trace-bearing xylem-strands always break a little 
further up while the trace is in the cortex. This is exactly what occurs in 
the axis of the cone when a strand branches a little way above the departure 
of a trace ; very much the same thing occurs in the stem when the nodal 
wood breaks up a little way above the insertion of the leaf-sheath. In 
cones which, like that of E . limosum> have very little xylem, the 4 gap 5 
or break usually occurs very close to, though not immediately above the 
trace, and thus the mesh of parenchyma approximates more closely to 
Jeffrey’s conception of a gap. In the cones of E. arvense and E. palustre, 
when the xylem is broken above a trace, pith and cortex remain separated 
1 The italics are Jeffrey’s. 
