October 17, 1901] 



NA TURE 



617 



addition, there are two or three small accessory steles lying 

 within the vascular ring. Throughout the internode the course 

 of these internal steles is quite free from the vascular ring, but 

 at each node one of them approaches the free margin of the leaf- 

 gap, and completely fuses with it, separating off again after the 

 leaf-gap has become filled up. Pleris elata var. Karsteniaita has 

 a typically solenostelic vascular ring, and also possesses internal 

 accessory steles, which behave like those of Diiksonia rttbt- 

 ginosa, but they are relatively larger, and frequently they all 

 fuse up together so as to form a second, inner, completely closed 

 vascular ring. It is suggested that the several internal steles 

 and vascular rings that occur in the Saccolomas and in Matonia 

 tectinata are also of the same origin and nature as those 

 described by the author. 



Prof. Bower, F. R.S., exhibited a specimen of I 0/>/;/(>j'/oj«/ot 

 simplex, n. sp. , collected by Mr. Ridley in Sumatra. It appears 

 to be entirely without the sterile leaf-lobe, though the fertile 

 spike is characteristically that of an Ophioglossuni . If it be 

 actually demonstrated that the sterile lobe is really absent, this 

 peculiar plant may give rise to considerable morphological 

 discussion. 



The anatomy of Ceratopteris tkalictroides, by Sibille O. 

 Ford. Ceratopteris tkalictroides is the single member of the 

 Parkeriacefe. It is an annual aquatic fern which occurs in the 

 tropics, either rooted in the mud or floating freely. The stem 

 is much reduced ; sterile as well as fertile leaves are found, both 

 kinds bearing numerous vegetative buds. The sporangia are 

 scattered on the under side of the fertile leaves, and have no 

 true indusium. The roots in the mature plant arise from the 

 bases of the petioles. An account was given of the anatomy of 

 the leaves, roots and polystelic stem. The ape.x of the stem 

 was described as having the form of a cone terminating in a 

 three-sided cell. Miss Ford spoke of Ceratopteris as possessing 

 more strongly marked affinities with the PoIypodiacCEe than 

 with any other of the leptosporangiate ferns, and as possibly 

 intermediate in position between the Marsiliace;^ and Poly- 

 podiaceiE. 



On two Malayan " myrmecophilous " ferns, by R. H. Yapp. 

 Polypodium {Lecaiiopteris) caynosuni and Polypodium siniiosum 

 are two epiphytic ferns, which occur almost exclusively in 

 the Malay Peninsula and Archipelago. Their creeping rhizomes 

 are thick and fleshy, the ventral surface closely adhering to the 

 substratum, the dorsal bearing the leaves, which are articulated 

 upon large conical leaf-cushions. Branching is lateral, and is 

 so frequent in the case of Polypodium carnosuin that thick com- 

 pact masses of interlacing stems are formed, which completely 

 encircle the branches of the trees on which the fern grows. The 

 fleshy stems of both ferns are traversed by an extensive system 

 of hollow spaces, which are invariably inhabited by colonies 

 of ants. These "ant-galleries" are arranged on a perfectly 

 definite plan, the details of which differs to some extent in the two 

 ferns. In both cases there is a single main ventral gallery, 

 which runs in a longitudinal direction through the stem, giving 

 off a lateral gallery to each branch and a dorsal one to each 

 leaf-cushion. The galleries are formed by the breaking down 

 of a large-celled, thin- walled tissue, which in the youngest parts 

 of the stem appears to function as a water-reservoir. Though 

 undoubtedly closely allied species, these ferns have been placed 

 by many authorities in different genera. 



Mr. George Brebner gave an account oi the anatomy of 

 Danaea and other MarattiaceK. In Danaea simplicifolia the 

 primary vascular axis is a simple concentric stele. The peri- 

 cycle may be absent or only imperfectly represented. There is 

 a definite endodermis, but it is not clear that the constituent cells 

 are always the innermost ones of the extrastelar tissue. When 

 the cotyledon-trace is about to be given off, the xylem of this 

 vascular axis, or " protostele," is separated into more or less 

 unequal portions by a layer of parenchyma. The parenchyma 

 increases in amount, and ultimately the cotyledon-trace is 

 separated from the central stele. The cotyledon-trace is col- 

 lateral. The next few leaf-traces are given off in the same 

 manner, and are also collateral. The stele resumes its simple 

 " protostelic " appearance. As further leaf-traces depart from, 

 and root-traces join, the vascular axis, the primitive structure 

 is gradually modified, and it may become more or less cres- 

 centic, forming an incomplete, or even complete, gamostelic 

 ring. The spaces left by the departure of the leaf-traces now 

 constitute leaf-gaps. The vascular tissue of this stage may be 

 described as a " siphonostele with leaf-gaps."' In describing the 

 stele of the Maraitiacere, the author confirmed and extended 



\0. 1668, VOL. 64] 



Miss Shove's statement (Annals So!., 1900) as to the internal 

 position of the protophlrem. 



On the anatomy of Todea, with an account of the geological 

 history of the Osmundace*, by A. C. Seward, F. R.S., and 

 Miss S. O. Ford. In this paper the authors dealt with the 

 anatomy of the stem of Todea barbara, which in the main 

 agrees with that of Osmunda regalis, as described by Zanetti 

 (Bot. Zeituiig, 1S95). The paper included an account of the 

 origin of the leaf-traces, the anatomy of the " seedling " plants 

 and a summary of the geological history of the Osmundacei«. 



Remarks upon the nature of the stele of Eqiiisetutii, by J. T. 

 Gwynne-Vaughan. The vascular bundles of Eqiiisetiim are 

 usually compared with those of a monostelic phanerogam, both 

 in structural detail and with regard to their course into the 

 leaf. Observations made upon the stems of E. Telmateja, &c. , 

 show that this comparison cannot be satisfactorily maintained. 



The xylem of the so-called vascular bundle of Equisetum was 

 described as consisting of three strands, two of which are lateral 

 and cauline, while the median, or carinal, strand is common to 

 both stem and leaf. The fact that only a small portion passes 

 out as a leaf-trace, and not the bundle as a whole, consiitutes 

 an essential point of difference between it and the bundle of a 

 phanerogam. Potonie has established a comparison between 

 the secondary vascular tissues of the Calamariae and the 

 Sphenophyllaceae by mentally doing away with the central mass 

 of primary .xylem that exists in the latter. By inverting this 

 procedure, and considering it possible that the ancestors of the 

 equisetums may have possessed a xylem that extended to the 

 centre of the stem, one is led to derive their structure, as it 

 exists at present, from the modification of a stele with a solid 

 central mass of centripetal xylem, such as that of Spheno- 

 phylhim, or of certain Lepidodendrea;. 



It is suggested that the lateral xylem strands in the vascular 

 bundles of the existing equisetums may perhaps be taken to 

 represent the last remnants of a primitive central mass, and 

 that this would be entirely in agreement with their apparently 

 centripetal development, and in particular with their cauline 

 course. 



Fossil Plants, &'c. — On a primitive type of structure ia 

 Calamites, by D. H. Scott, F. R. S. Palxontological research 

 has afforded evidence that the horsetails and lycopods had a 

 common origin. The class sphenophyllales, restricted, so far 

 as we know, to the Palaeozoic epoch, combines in an unmis- 

 takable manner the characters of equisetales and lycopodiales, 

 while at the same time presenting peculiar features of iis own. 



The synthetic nature of the sphenophyllales, indicated clearly 

 enough in the type-genus Sphenophylliim itself, comes out still 

 more obviously in the new genus Cheiroslrobns. So far nothing 

 has been found to bridge the gulf which separates the anatomy 

 of the Calamariea: (Pakieozoic equisetales) from that of the 

 sphenophyllales or the lycopods. 



Dr. D. H. Scott gave an account of a calamite from the 

 Calciferous Sandstone of Burntisland, in which each vascular 

 bundle is characterised by the possession of a distinct arc of 

 centripetal wood on the side towards the pith. The carinal. 

 canals are present, as in an ordinary calamite, and contain, as 

 usual, the remains of the disorganised protoxylem. They do 

 not, however, as in other equisetales, form the inner limit of 

 the wood, but xylem of a considerable thickness, and consist- 

 ing of typical tracheides, extends into the pith on the inner side 

 of the canal, which is thus completely enclosed by the wood. 

 That the organ was a stem, and not a root, is proved, not only 

 by the presence of the carinal canals, but by the occurrence of 

 nodes, at which the outgoing leaf-traces are clearly seen. This 

 appears to be the first case of centripetal wood observed 

 in a calamarian stem, and thus serves to furnish a new link 

 between the Pateozoic equisetales and the .sphenophyllales, and 

 through them with the lycopods. 



Provisionally, the new stem may bear the name of Calamites 

 pcttycurensis, from the locality where it occurs. 



In a paper on the past history of the Yew in Great Britain and 

 Ireland, Prof. Conwentz (Danzig) gave an account of his re- 

 searches into the causes of the disappearance of this species from 

 nearly all parts of middle and northern Europe. He expressed 

 the view that the genus Taxus, which has now passed its zenith, 

 is of no great geological antiquity ; most of the Tertiary fossils 

 described as species of yew were found to have been incorrectly 

 determined. Prof. Conwentz dealt with a mass of evidence 

 which he had examined, proving that the yew had been formerly 

 widely distributed in regions where it has ceased to exist. Th« 



