1893. THE FRUIT-SPIKE OF CALAMITES. 357 
the axis of the Calamostachys. These differences appeared to me too 
great to make it possible for the one ever to have been a prolongation 
of the other.” 
Thus up to his latest utterances on the subject Williamson 
refused to recognise Calamostachys Binneyana as the fruit of Calamites, 
and justly insisted upon the difference between the anatomy of its 
axis and that of the stem of Calamites as being strong evidence against 
such a view. Heeven went further than this. So far back as 1874 
he maintained (12) ‘that the only British strobilus of which the 
internal organisation has hitherto been described, that has any claims 
to be regarded as the fruit of Calamites,” is that which he figured 
and described in the Tvansactions of the Literary and Philosophical 
Society of Manchester in 1869. Substantially the same statement is 
made in the memoir of 1888 already referred to, so that on both 
positive and negative grounds he refused to recognise any connection 
between Calamostachys Binneyana and Calamuites. 
Such was the state of opinion among paleobotanists when the 
new and much better-preserved specimens already referred to came 
into the writer’s hands. Looked at from the botanist’s point of view, 
it is obvious that the divergence of opinion is based upon the fact 
that there is a sort of inconsistency, if the expression may be allowed, 
between the external characters of the spike and the internal anatomy 
as hitherto understood. As already pointed out, the former have so 
close a resemblance to those of an Egquisetum spike, that one naturally 
looks for the parent plant of Calamostachys Binneyana among those fossil 
forms most nearly allied to Equisetum, and by a short step we come to 
Calamites; but, on the other hand, the internal anatomy as described 
by Carruthers, Binney, and Williamson, is so irreconcilable with the 
anatomy of the:stem of Calamites as to justify much that the last 
authority has written in opposing the Calamitean affinities of the 
spike. 
An examination of the new material gave what the writer thinks 
is a complete solution of the difficulty thus presented, and at the 
same time indicated in what direction to look for the reconciliation of 
these diverse opinions. 
In the first place, it soon became evident that the centre of the 
axis of Calamostachys Binneyana was not vascular, as had so frequently 
been stated, but was composed of cellular tissue which constituted a 
true pith. In 1891, when drawing up the first part of an Index to 
his Memoirs, Williamson introduced a brief footnote (13) in connection 
with Calamostachys Binneyana, which shows that he was beginning to 
have doubts on this point, and he admits that in the specimens 
described in 1874 ‘‘the elongated medullary cells” were ‘‘ mistaken 
for tracheids.” He says nothing, however, as to whether this 
parenchyma is a true pith, such as we find in Calamites, or merely a 
central parenchyma like that found in the stele or vascular cylinder 
of some Lepidodendva. On this point, however, the sections referred 
