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PKOGEESS OF MICKOSCOPICAL SCIENCE. 
Structure of Fossil Goal-plants. — Professor Williamson, F.E.S., 
continues to give the Royal Society valuable papers on this subject. 
The last presented was upon Ferns and Gymnospermous Stems and 
Seeds. The author described the stem of a new fern, in which the 
principal vascular axis formed a cylinder enclosing a medulla, as in 
some Lepidodendra. This vascular cylinder gives off secondary 
bundles, to petioles, and rootlets, and each vessel is filled with 
tylose. Two kinds of Fern-sporangia were described — one Polypo- 
diaceous, with a straight, vertical annulus ; the other, with the annulus 
horizontal and subterminal, exhibits a type seen in the recent 
SchizaBacesB and Gleicheniaceae. But the chief subjects of the memoir 
are the stems and seeds of Gymnosperms. Of the former various 
modifications of the Sternhergian Dadoxylons are described, and shown 
to correspond very nearly to many recent conifers, though with dis- 
tinctive features of their own, especially in the structure of their 
woody fibres, and in the leaf-bundles of some species being given off 
in pairs. The author still excludes the Sigillarise from the Gymno- 
spermous group. The most important novelties are the Gymnospermous 
seeds, exhibiting their internal organization, found in France by M. 
Grand-Eury, and by the author in this country. Of these he de- 
scribes a number of new genera and species in addition to the Trigo- 
nocarpons previously described by Mr. Binney and Dr. Hooker. The 
most remarkable of these is one designated Lagenostoma ovoides, in 
which a large flask-shaped cavity, enclosed within a crenulated 
canopy, occupies the apical end of the seed, between the apex of the 
endosperm and the exostome. Brongniart believed, with reason, that 
such cavities have originated in the absorption of the apex of the 
nucleus, leaving the corresponding part of the nucular membrane to 
form the cavity or " lagenostome." In this lagenostome large pollen- 
grains are found in many cases. Brongniart designates it the " Cavite 
pollinique." Examples of several other seeds presenting generic and 
specific modifications of the same type, as well as several species of 
the well-known genus Cardiocarpum and of Trigonocarpum. In all 
these the primary nucleus seems to have been absorbed, being now 
only represented by the investing nucular membrane. Within this is 
an inner structureless bag, which, in some of the Cardiocarpa, is 
filled with parenchyma, and which appears to represent the secondary 
perispermic membrane, or what is really the endospermic membrane, 
or primary embryo sac of the Gymnosperms. The intimate structure 
of Trigonocarpum agrees with Dr. Hooker's description of it so far as 
the longitudinal sections are concerned, save that here, also, a " cavite 
pollinique " exists. Transverse sections show that the well-known 
sandstone casts of Trigonocarpum do not represent the external form 
of these fruits, but are casts of the interior of the hard endotesta. This 
latter was not trigonous externally, like the common specimens, but 
had twelve longitudinal ridges, three of which, corresponding with 
