April ^, 1889] 



NATURE 



551 



Linnean Society, March 21. — Mr. Carruthers, F.R.S., 

 President, in the chair. — Mr. T. Christy exhibited the pod 

 (36 inches in length) of an Apocynaceous plant received from 

 Gaboon as Strophanthus, but believed to be allied to the 

 Holarrhena. — Prof. Stewart, referring to the specimens of 

 Noctilio Uporinus exhibited at the last meeting of the Society, 

 stated that he had examined the contents of the stomachs sub- 

 mitted to him by Mr. Harting, and had found without doubt 

 fragments of fish, scales, and fin-rays, and a portion of the lower 

 jaw of a small fish, proving the correctness of the assertions 

 which had been made regarding the piscivorous habits of this 

 bat. — Mr. W. B. Hemsley furnished a report on the botanical 

 collections made on Christmas Island during the voyage of the 

 Egeria. This included a complete list of the plants collected, 

 with remarks on their general distribution, the author being of 

 opinion that the flora of this island, which lies about 200 miles 

 south of the western end of Java, was more nearly related to 

 that of the Malayan Archipelago than to that of Australia. Mr. 

 C. B. Clarke, commenting on the author's observations on the 

 buttresses of trees, described some remarkable instances which 

 he had seen of this singular mode of growth. Mr. J. G. Baker, 

 referring to the Ferns which had been collected, noticed their 

 affinities and distribution. Mr. R. A. Rolfe commented on 

 three species of Orchids which had been brought home by this 

 Expedition, all of which were new. Mr. Thiselton Dyer, re- 

 ferring to Mr. Lister's Report to the British Association on the 

 zoological collections from this island, in which it was stated 

 that the character of the avifauna was Australian, considered that 

 this was not borne out by an examination of the flora, which was 

 decidedly Malayan. — A paper was then read by Mr. R. A. Rolfe 

 on the sexual forms of Catasetum, with special reference to the 

 researches of Darwin and others. The purport of Darwin's 

 paper (Journ. Linnean Soc, 1862) was to show that Catasetum 

 Jridenlatiim had been seen by Schomburgk to produce three 

 different kinds of flowers, belonging to the same number of sup- 

 posed genera, all on the same plant, and that the three repre- 

 sented respectively the male, female, and hermaphrodite states 

 of the species. Mr. Rolfe showed that Schomburgk's remarks 

 applied to two distinct species, C. tridentatiun and C. barbatum, 

 the females of which resembled each other so closely that they 

 were thought to be one and the same — namely, Monacanthus 

 viridis. Neither of these, however, belonged to the true plant 

 of that name, which was really the female of another species — 

 namely, C. cernmim, a fact hitherto unsuspected. The key 

 of the situation was that the females of several species re- 

 semble each other very closely, and to three of them the name 

 Monacanthus viridis had been applied. — After some critical 

 remarks by the President and Mr. Bull, a paper by Mr. 

 MacOwan was read, on some new Cape plants. 



Geological Society, March 6.— W. T. Blanford, F.R.S., 

 President, in the chair. — The following communications were 

 read :— -On the subdivisions of the Speeton Clay, by G. W. 

 Lamplugh. Communicated by Mr. Clement Reid. The 

 reading of this paper was followed by a discussion, in which 

 Prof. Judd, Mr. Strahan, Prof. Blake, Mr. Hudleston, and Mr. 

 Herries took part. — Notes on the geolc^y of Madagascar, by 

 the Rev. R. Baron. Communicated by the Director-General of 

 the Geological Survey. With an appendix on some fossils from 

 Madaga-scar, by Mr. R. Bullen Newton. The central highlands 

 of Madagascar consist of gneiss and other crystalline rocks, the 

 general strike of which is parallel with the main a.xis of the 

 island, and also, roughly, with that of the crystalline rocks of 

 the mainland. The gneiss is frequently hornblendic ; its ortho- 

 clase is often pink ; triclinic felspar often occurs in places ; 

 biotite is the most common mica, but muscovite is not un- 

 common ; magnetite is generally present, often in considerable 

 quantities. The gneiss i, often decayed to great depths, form- 

 ing a red soil, and the loosened rock is deeply eaten into by 

 streams. The harder masses of gneiss, having resisted decay, 

 stand out in blocks, and have been mistaken for travelled 

 boulders of glacial origin. Other more or less crystallme 

 rocks are mica-schists, chlorite-schists, crystalline limestone, 

 quartzite (with which graphite is often associated), and clay- 

 slate. Bosses of intrusive granite rise through the gneiss. 

 That east of the capital contains porphyritic crystals 0/ felspar 

 which near the northern edge of the granite are arranged 

 roughly in a linear direction ; here also the granite contains 

 angular fragments of gneiss. For the most part the granite of 

 Madagascar is clearly intrusive, but this may not always be the ^ 

 case. The volcanic rocks are of much interest. The highest j 



mountains, those lying to the south-west of the capital, consist, 

 in their higher parts, of a mass of lava, for the most part 

 basaltic, but with some sanidine- trachyte. The lava-streams 

 are sometimes twenty-five miles long, and successive flows, up 

 to 500 feet in thickness, are exposed by the valleys. From the 

 great denudation which this area has undergone, and from the 

 fact that no cones now remain, we may assume that this volcanic 

 series is of some antiquity. Of the newer volcanic series there 

 are numerous very perfect cones, dotting the surface of the 

 gneiss in many places. No active volcano now exists in the 

 island, but the occasional emission of carbonic acid gas, the 

 occurrence of numerous hot springs and deposits of siliceous 

 sinter, and the frequency of small earthquake-shock.'^, seem to 

 show that volcanic forces are only dormant and not entirely 

 extinct. The ashes generally lie most thickly on the side of the 

 cone between north and west ; this is accounted for by the 

 prevalence of the south-east trade-winds. The volcanic areas 

 are ranged roughly in a linear direction, corresponding with the 

 longer axis of the island. Sedimentary rocks occur mainly on 

 the western and southern sides of the island. The relations of 

 these to each other have not yet been determined ; but from the 

 fossils (referred to the European standard) it seems that the 

 following formations are represented : Eocene, Upper Cre- 

 taceous, Neocomian, Oxfordian, Lower Oolites, Lias. Pos- 

 sibly some of the slaty beds may turn out to be Silurian or 

 Cambrian. The cr>'stalline schists, &c., are probably, for the 

 most part at least, Archaean. Recent deposits fringe the coasts, 

 and are largely developed on the southern part of the island. 

 East cf the central line of watershed there is a long depression 

 containing a wide alluvial deposit, probably an old lake-bed. 

 Terraces fringe its sides in many places. The lagoons of the 

 eastern coast are due to alluvial deposits. The paper concluded 

 with some remarks on the geological antiquity of the island, its 

 separation dating from early Pliocene times, if not earlier. This 

 is the conclusion arrived at by Wallace from its faiina ; the 

 author's detailed researches into its flora, recently described 

 before the Linnean Society, show that while about five-sixths of 

 its genera of plants are also found elsewhere, chiefly in tropical 

 countries, at least four-fifths of its species are peculiar to Mada- 

 gascar. The appendix, drawn up by Mr. R. Bullen Newton, 

 consisted of notes upon the fossils collected by the author, with 

 tables, and descriptions of two new species — namely, Astarle (?) 

 Baroni and Spheera madagascariettsis, both from deposits of 

 Lower Oolitic age. — Notes on the petrographical characters of 

 some rocks collected in Madagascar by the Rev. R. Baron, by 

 Dr. F. H. Hatch. Some remarks on Mr. Baron's paper were made 

 by the President, Dr. Geikie, Mr. H. B. Woodward, and Mr. 

 Topley. 



Paris. 

 Academy of Sciences, March 25. — M. Des Cloizeaux, 

 President, in the chair.— On the achromatism of interferences, 

 by M. Mascart. The conclusions arrived at by Cornu and Stokes 

 are here applied to the particular cases of interference fringes 

 and of Newton's rings. In the phenomenon of W. Herschel's 

 fringes the condition of achromatism is shown to be — 

 cos- i _ x sin A 

 sin i cos/* 



— Remarks accompanying presentation of Prof. Karl Pearson's 

 work, "The Electrical Researches of Barre de Saint- Venant " 

 (Cambridge, 1889), by M. Boussinesq. The period from 1850 

 to 1886, covered by this important treatise, comprises the most 

 remarkable researches, by the late M. de Saint- Venant, on 

 torsion, flexion, live resistance, the distribution of elasticities in 

 heterotrope bodies, plasticodynamics, &c. The work, which will 

 be found of great service to English physicists, geometricians, 

 and engineers, unfamiliar with the French language, forms the 

 first part of the second volume of the series begun by Todhunter 

 on the "History of the Theory of Elasticity." — On elliptical 

 polarization by vitreous reflection, by M. A. Potier. Rejecting 

 Cauchy's assumption of evanescent longitudinal waves, the 

 author here develops a theory in which he takes as his starting- 

 point the dilTerential equations of the vibratory movement. The 

 principle and results of this theory were already announced at the 

 meeting of the French Association for the Advancement of the 

 Sciences in 1872. — Researches on the cultivation of the potato, 

 by M. Aime Girard. The author here deals with the progressive 

 development of the plant, and arrives at the general conclusion 

 that the origin of the starch is to be sought in the leaves, where it 

 is probably represented in its initial form by saccharose, or 



