262 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
less can we at present associate them with any of the stems and leaves with which 
students of Carboniferous vegetation are so familiar. I cannot, for instance, follow 
Dr. Dawson and Prof. Newberry in identifying Trigonocarpon with Sigillaria , merely 
because the former seeds have sometimes been found accumulated near the bases of the 
erect stems of the latter. We have numbers of magnificent stems of Sigillarice in 
Britain, and yet I find no one instance recorded of the two objects being so associated 
in our British deposits. Evidence of this kind requires to be received with the utmost 
caution. In time, I doubt not, some of these seeds will be found attached to peduncles 
from the structure of which much will be learnt ; until then we must be content to 
wait. One lesson we may certainly learn from the numerous species of these seeds with 
which we are already familiar, viz. that there were, in the Carboniferous forests, many 
Gymnospermous stems clothed with foliage, of which we have not yet discovered any 
traces, probably because, as has more than once been suggested, these Gymnosperms 
did not flourish upon the low swampy grounds which were the homes of the great mass 
of the coal-producing plants. 
M. Brongniart’s observations on the fertilized ovules of Ceratozamia Mexicana and 
C. Ghiesbrechtii, just referred to (loc. cit. p. 305), show that, in them, the apical extremity 
of the unfertilized nucule projected as a mamilliform prolongation which occupied and 
filled much of the micropyle. My Lagenostoma physoides (figs. 77 & 78) exhibits a 
similar termination to the nucleus. M. Brongniart concluded that the mamilliform 
projection of the nucleus became absorbed, forming, by the disintegration of its cells, 
the “ cavite pollinique ” of his memoir, and which I have termed the lagenostome. If 
this is the case, the similar mamilla in figs. 77 & 78 cannot be the same structure as is 
seen in the Cycadean ovules, because the narrow prolongation of its upper part is here 
retained in its integrity, whilst the lagenostome (figs. 77, c , & 78, c ) is superadded 
to and not formed out of that structure*. M. Brongniart’s idea that all these 
seeds are Cycadean rather than Coniferous must also await further inquiry before we 
can either accept or reject it. If the grains discovered in several of the lagenostomes 
are truly pollen-grains, their presence indicates that the seeds containing them were 
* My latest studies seem to favour M. Brongniart’s conclusions thus far, viz. that the central organ of each 
of these seeds which, in the course of the memoir, has been termed “ the nucleus,” may really he the endo- 
sperm found in the interior of the original nucleus, the tissues of the latter structure having been entirely 
absorbed. In this case the only traces of the original contour of that nucleus are now found in what I have 
termed “ the nucular membrane ” and its lagenostomal prolongations. If this he correct, it then becomes pro- 
bable that the remarkable cluster of parenchymatous cells seen in the interior of the “lagenostome” or “ cavite 
pollinique ” of so many of my specimens, and the origin of which is so difficult to explain, is neither more nor 
less than the remains of the cellular tissue of the uppermost extremity of the original nucleus, which primarily 
formed its narrowed apical extension occupying the micropyle, and which was not absorbed when the rest of 
the nucleus disappeared. The acceptance of these conclusions would bring my observations upon the Carboni- 
ferous forms into close harmony alike with those of M. Miguel (‘Archives Neerlandaises,’ t. iii., 1868) and 
of M. Brongniart upon the fertilized and unfertilized ovules of living Cycads. Of course the conclusion would 
follow that the affinities of these fossil forms is Cycadean rather than Coniferous. 
