64 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
matured and required liberation. Why a larger number of the mother-cells did not 
contain more than one spore is but one of the many anomalies seen in this very per- 
plexing fruit. The further question now arises — To what plant does this Strobilus 
belong 1 
Mr. Binney answers this question by affirming that it is the fruit of Calamodendron ; 
and Mr. Carruthers, regarding it in the same light, says that it is the fruit of a Cata- 
mite. The latter observer arrives at this conclusion under the conviction that Calamites 
and Asterophyllites are identical plants. The spores throw little light upon this problem, 
because they exhibit too generalized a form to indicate any special relations. Mr. 
Carruthers has referred to the semispiral deposits in the cells of the sporangia as 
representing the true spiral fibres in the sporangial cells of Equisetum. But such 
deposits are not confined to Equiseta. We have them in the corresponding sporangial 
cells of Marchantia conico , in a condition much more closely resembling those of our 
fossil fruit than do the Equisetaceous ones. The sporangia of our fossil very closely 
resemble those of Equisetum both in their form, in the mode of their attachment to the 
sporangiophores, and in the general aspects of the latter organs ; but they differ in the 
fact that only alternate verticils of the nodal expansions bear sporangia in the fossil, 
whereas they are attached to every verticil in the recent type. It appears to me that in 
the former the sporangia are ruptured by detachment from the sporangiophore, instead of 
by longitudinal ventral dehiscence as in the latter. When we come to the central axis, 
the difference between the two types becomes increasingly manifest ; though even here 
we are not without some curious features of resemblance. If we make a transverse 
section through the node of a recent Equisetaceous strobilus, in the jplane of a verticil of 
sporangiophores , we see that the bark from which these sporangiophores spring expands 
into a small lenticular disk, the structure of which is almost identical with that of the 
sterile disks of Calamostachys , as seen in Plate VI. fig. 34, and proportionately different 
from the corresponding section of the fertile sporangiophores represented by Plate VI. 
fig. 36. Thus we have agreement between the recent and fossil types in the structure 
of parts whose general aspects are so different, and differences of structure where the 
outward forms agree. The double layer of the bark of Calamostachys corresponds 
exactly with what we have in Aster ophyllites, whilst this tissue consists of a single 
uniform layer in Calamites* . This is a distinction of the greatest importance. It 
would be contrary to all experience to expect to find so great a change in a continuous 
aerial bark investing the stem and the fruit-axis of a Cryptogam as would be involved 
in the sudden separation of a single parenchymatous bark into two strongly marked 
layers of parenchyma and prosenchyma. Yet we have to admit the possibility of such 
an anomalous condition as is here suggested, if we are to recognize in Calamostachys 
the fruit of Calamites. 
The vascular part of the axis differs from the corresponding portion of Calamites even 
yet more than the bark does, approximating in the same ratio to that of Aster ophyllites. 
* See my memoir on Calamites. Phil. Trans. 1871, Plate xxm. fig. 9. 
