Anatomy of Solenostelic Ferns : /. Loxsoma . 73 
unfused steles) is merely one of degree, cases often arising 
in which it is no easy matter to decide which is the more 
suitable expression to use. Therefore, since the utility of 
a descriptive term will be the greater the more it is suscep- 
tible of accurate delimitation, it will be advisable to state at 
once that a solenostelic stem, as understood in this paper, 
may be defined as one in which the vascular tissue is arranged 
in a single hollow cylinder with phloem and phloeoterma on 
either side, the complete continuity of which is interrupted 
only by the departure of the leaf- traces ; the gaps thus pro- 
duced being closed up in the inter node above before the departure 
of the next leaf -trace. 
Whilst engaged in the preparation of this paper I was 
privileged to see an advanced copy of an exceedingly inter- 
esting and suggestive paper by Dr. Jeffrey 1 , in which Van 
Tieghem’s terminology is discussed at some length, and pre- 
cisely the same opinion regarding the misleading nature of the 
term gamostely is arrived at (l.c., p. 605). Jeffrey has proposed 
an altogether new terminology based upon the word siphono - 
stele, which, I take it, may be defined as a fibro-vascular tube 
interrupted by lacunae opposite the points of departure of 
branches, or of leaf-traces (l.c., p. 632). Although I am not 
yet prepared to accept all the phylogenetic relationships 
that are to be inferred from Jeffrey’s system, in particular 
that relating to the Phanerogamic medullated monostele, 
yet many of the distinctions made are peculiarly fortunate, 
and coincide with structural features of crucial importance. 
In • any case, no specific term is supplied for the particular 
vascular arrangement defined above as solenostelic, to which 
I believe it will be found convenient, in describing the 
anatomy of the Ferns, to give a name of its own. According 
to Jeffrey’s terminology, solenostely would be regarded as a 
special type of amphiphloic phyllosiphony . 
Although the solenostelic type of vascular structure is in 
general one of very rare occurrence, still a fair number of 
1 The Morphology of the central Cylinder in the Angiosperms ; Transactions of 
the Canadian Institute, vol. vi, p. 599. 
