416 BOTANICAL GAZETTE [DECEMBER 
It is fair to note that Zenetti dissented4* from the prevailing 
view, and evidently for the reason that he attached some value 
to the nature of the central cylinder from the phylogenetic 
standpoint. Hence he sought to find the same type amongst 
the vascular cryptogams. He rejected the ordinary fern type 
because it is ‘polystelic,” and the lycopod type because there 
is no pith, obviously overlooking Se/aginella laevigata, Phylloglos- 
sum, etc. So finding no living form with which comparison could 
be established he turned to paleophytology. Among the Lepi- 
dodendraceae he found the prototype sought for, especially in 
such of these fossils as L. Harcourtii, and the Sigillarians, because 
in these the wood is broken into bundles between which there 
are medullary rays. But he evidently did not grasp the signifi- 
cance of bundles and medullary rays in relation to leaf traces 
and branch traces. In O. regalis, too, the protoxylem is endarch, 
while in those ancient lycopods it was exarch. The stele of the 
Lepidodendraceae, as in all plants bearing palingenetically small 
leaves, was cladosiphonic, while O. regalis is phyllosiphonic, as 
are all primitively megaphyllous plants. Hence any attempt to 
establish a relation between the central cylinder of modern ferns 
and of those ancient horsetails must fail. Indeed, of the early 
fossil forms preserved, the one with a central cylinder most 
closely resembling that of the Osmundaceae, as has been pointed 
out by Dr. Scott,#" seems to be the cycadofilicinean Lyginoden- 
dron ( fig. 26). 
Further, we dissent just as strongly from the view that the 
family is anomalous in the matter of its vascular system. The 
typical fern stem possesses an amphiphloic siphonostele, as is 
especially revealed by a study of development. But degenerated 
forms of this are to be met with in almost every family, some 
examples of which have been noted. The Osmundaceae, as has 
been shown above, all exhibit some degree of degeneration from 
this type. It is therefore evident that the cauline vascular sys- 
tem of this family is neither primitive nor anomalous among the 
Filicales. 
* ZENETTI: of. cit. 73. 4ESCOTT : of. cit. 
