jd^ 



NA TURE 



[Fehkuaky 13, 1902 



■ rigorously the analogous theorems, so far as they exist, for the 

 homogeneous linear differential equations of the second order. 

 The article closes with some applications. — Space of constant 

 curvature, by F. S. Woods, is an attempt to present Riemann's 

 ideas (if. the " Ueber die llypothesen, wclcheder tleometrie ku 

 (Irunde liegen") in an elementary form. The paper is given 

 in part and is useful, in addition to the results worked out, for 

 its bibliographical references. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, January 23.— "The Affinity of Tmesipteris 

 with the Sphenophyllales." By A. P. W. Thomas, .M.A., 

 F. L.S., University Colleije, Auckland, New Zealand. 



In the present paper the author deals with the nature of the 

 synangium of Tmesipteris, as based on the study of variations 

 observed in the sporophyll, beyond the limits already recorded 

 by Bower. 



The term "sporophyll" is used to denote the whole fertile 

 structure, the term " synangium " restricted to the spor- 

 angiophorc. Three types of variation are recorded, viz. (i) 

 that of repeated dichotomy of the sporophyll with two to 

 three synangia ; (2) that in which the synangium is raised upon 

 a pedicel or stalk ; (3) that in which the synangium is replaced 

 by a leaf-lobe of normal appearance. It is shown that ab- 

 normality in the sporophylls and synangia, which commonly 

 occurs at the beginnings or ends of the fertile zones, is not found 

 in cases where the sporophyll shows excessive leaf development. 

 In these it occurs rather towards the middle region, and it is 

 inferred that if the nutritive conditions remained equally satis- 

 factory throughout, the whole sporophyll series should show 

 repeated dichotomy. 



Concerning the second type of variation, the synangium is 

 found to have become so revolved upon a transverse axis that 

 its longitudinal groove faces outwards between the leaf-lobes, 

 assuming a position the more favourable to dispersal of the 

 spores. In the third type the leaf is shown to be forked, 

 although the synangium, if present at all, exists only in an 

 abortive form. From the fuller study of this, the author sug- 

 gests that the synangium is the morphological equivalent of 

 a ventral leaf-lobe. 



Passing to questions of classification, the author refers to the 

 difficulties in reconciling the sporangium-bearing structures of 

 the Psilolce with those of the typical Lycopodina:. He enters 

 into a comparison with the extinct Sphenophyllales, with 

 especial reference to Bowmanites and Cheirostrobus, and con- 

 cludes that the relationships of Tmesipteris and Psilotum with 

 this group are perhaps even closer than is supposed by Scott. 



In an addendum, received since this paper was announced, 

 the author makes good his desire to deal extensively with the 

 Psilotum sporophyll, the leaves of which, though greatly 

 reduced and xerophytic, are shown to be essentially similar to 

 those of Tmesipteris. 



Society for Psychical Research, January 31. — Dr. Oliver 

 Lodge, F. R.S., delivered his presidential address. Dealing first 

 with the phenomena of trance, lucidity and clairvoyance, he 

 expres.sed the opinion that much more information was required 

 before we could even formulate the problems raised by these 

 faculties. With regard to physical phenomena, he thought much 

 of the extra difficulty of accepting evidence for unusual 

 phenomena was due to the a priori notion that such occurrences 

 are contrary to natural law. We cannot, however, clearly tell 

 that they are contrary to natural law ; they are only contrary to 

 and supplementary to our usual experience. The objection of 

 science to psychical research is mainly due to the fact that it 

 regards psychical phenomena as unintelligible. It is accustomed 

 to simplify its problems by the method of alistr-^ction and has got 

 into the habit of thinking that it actually excludes disturbing 

 causes ; the abstraction cannot really exclude from the universe 

 anything apparently disorderly. Theoretically, this is uni- 

 versally admitted ; practically science has excluded psychical 

 phenomena from its experimental area. He was not prepared 

 to say that physical phenomena such as materialisations, the 

 passage of matter through matter, and levitaiion were impossible 

 and absurd, so that no testimony ought to produce any effect on 

 our incredulity. Extreme caution was necessary and full control 

 must be allowed to the observers. His personal belief was that 



NO. 1685, VOL. 65] 



man survived death, and this belief had been produced b 

 scientific evidence. He did not attribute the physical phenomena 

 of spiritualism to ihe agency of the departed, but was disposed 

 to regard trance utterances as in some cases due to telepathic 

 communication with some unconscious stratum of a departed 

 person. 



Royal Microscopical Society, January 15. — Mr. Wm. 

 Carruthers, F. K. S. , president, in the chair. —This being theannual 

 meeiing of the Society, the president gave an address on the 

 scientific work of Nehemiah Grew, from 1641-1712, whom he 

 defended from the charges of plagiarism which had been brought 

 against him in respect to his discoveries as to plant structure. — 

 Mr. E. A. Parsons gave an exhibition of malaria parasites under 

 a number of microscopes, lent for theocca-sinn by Messrs. Chas. 

 Baker. — Messrs. Ross exhibited their new form of standard 

 microscope, designed specially for the use of medical students, 

 fitted with a new form of fine adjustment. .Messrs. Ross also 

 exhibited a simple lens for dark ground illumination. It consists 

 of a meniscus lens bored through its centre to receive a spot 

 made of vulcanite provided with a stem to drop into the hole in 

 the centre of the lens. 



Geological Society, January 22.— Mr. J J. H. Teall, 

 V. P. R. S., president, in the chair. — The fossiliferous Silurian 

 beds and associated igneous rocks of the Clogher Head district 

 (county Kerry), by Prof. S. H. Reynolds and Mr. C. I. 

 Gardiner. The authors give a detailed description of the coast 

 from Dunquin past Clogher Head to Coosglass (south of Sybil 

 Point), and of the western side of Smerwick Harbour. They 

 next deal with the inland exposures, which are not very frequent, 

 but include considerable rock-masses at Croaghmarhin and 

 Minaunmore Rock. The rocks consist of sandstones, slates, 

 calcareous flags, ashes and ashy conglomerates, rhyolitic lava- 

 flows and various intrusive rocks. The general structure is an 

 S-shaped fold, inverted towards the north so that the dip of the 

 beds is approximately south-easterly, and the oldest beds occur 

 to the north, at Coosglass. Both anticline and syncline are 

 faulted, and a patch of Old Red Sandstone is caught in under the 

 synclinal thrust at Coosmore. Fossils, mainly corals, brachio- 

 pods, lamellibranchs and gasteropods are fairly abundant ; but 

 trilobites are rare and graptolites absent. The whole of the 

 fossiliferous rocks are of Silurian age ; the majority of those 

 exposed on the coast are of Wenlock or Wenlock-Llandovery 

 age, while the majority of those exposed inland are of Ludlow 

 age. — A process for the mineral analysis of rocks, by Prof. 

 W. J. Sollas, F R. S. The method proposed is to obtain a 

 quantitative estimation of the mineral composition of a rock, and 

 from the known composition of the minerals to calculate the 

 percentage-composition of the rock. The specific gravities of 

 the minerals are first determined by means of a diflfusion-column 

 of methylene-iodide and beads of known specific gravity, and 

 the presence or absence of particular minerals settled for a 

 certainty. Next, the separation of the minerals in a weighed 

 quantity of the powdered rock is undertaken by means of a 

 special separator, the method being illustrated l)y the example 

 of a rock containing orthoclase (sp. gr. 256), quartz (2'65), 

 andesine (2'67), biotite (3'i), pyroxene (3"3) and magnetite. 

 The first separation would be with a liquid of sp. gr. 2 885, the 

 mean of that of andesine and biotite ; the next with a liquid of 

 sp. gr. 266 ; the next 2605. and so on for the other con- 

 stituents. The separated minerals ate dried and weighed, the 

 loss distributed, and the analysis checked by comparing the 

 specific gravity of the rock in bulk with that calculated from 

 the specific gravity and proportion by weight of its constituents. 



Dublin. 



Royal Iriata Academy, January 13. — Prof. R. Atkinson, 

 president, in the chair — Prof. T. Johnson communicated, on 

 behalf of the fauna and flora committee of the Roy:<| Irish 

 Academy, a paper by Mr. W. West and Prof. G. S. West en- 

 titled " A Contribution to the Freshwater iWf^x of the North of 

 Ireland." This paper gives the results of Ihe examinaiion of 

 material collected by the authors in 1900 and 1901 in Lough 

 Ncagh and district, and in co. Donegal. 139 genera, 604 species 

 and 106 varieties are recorded. Of these sume Iwtlve, de- 

 scribed and illustrated, h,<ve been hitherto unknown, twenty-four 

 others are new to the British Isles, many others new to 

 Ireland, and the distribution of yet others, recorded by the 

 late Mr. W. Archer, F.R.S., and Rev. E. O'Meara, is largely 



