.594 



NATURE 



[April 24, J902 



A LARGE portion of part iii. and the whole of part iv. of the 

 Archives dc Zoologie expetimentaU for 1901 are occupied by an 

 elaborate dissertation on the structure and function of the ciliated 

 epithelium of animals — the result of experiments and investiga- 

 tions carried out by Monsieur P. Vignon during the last three 

 years. The main result of the observations, according to the 

 author, is to prove or confirm the existence of " biological 

 coordination." In the same journal M. E. Topsent describes 

 the sponges of the Algerian coast. 



VVe have received a copy of an interesting paper by Herr 

 W. Voight, from the Verhaiidlungen of the Natural History 

 .Association of Prussian Rhineland, &c., describing the exter- 

 mination of two species of annelids from the freshwaters of the 

 district and their replacement by a third. It appears that until 

 recently Plaitaria alpiiia inhabited the streams of the Hunds- 

 riickgebirge, in the northwestern Thuringerwald, and Polyulii 

 ioriiuta those of the Taunus. It is inferred that they have 

 been inhabitants of these regions since the Glacial epoch. At 

 first F. alpina alone inhabited both areas ; in the Hundsrlick- 

 gebirge it persisted, but in the Taunus its territory was invaded 

 by P. corntita, which became the dominant form. As the 

 climate grew warmer, a third species, Planaria goiwcep/iala, 

 appeared in the lower past of the streams, and has since been 

 gradually spreading upwards until it has replaced both the others 

 over the greater part of their area, the disappearance of P. alpina 

 from many streams in the one district and of P. corniita from 

 those of the other being recent events. 



It is but seldom that it falls to the lot of the same individual 

 to reoccupy the presidential chair of a scientific (or any other) 

 society after an interval of twenty-one years, and we have 

 accordingly much pleasure in ofl''ering our congratulations to 

 Prof. R. Meldola on his assumption of that position at the 

 recent " coming-of-age " of the Essex Field Club. Indeed, the 

 club is to be congratulated on the "staying powers" of its 

 officials generally, the president remarking that, with a single 

 exception, the whole of the office-bearers during its twenty-one 

 years of existence are still among us. Probably this is abso- 

 lutely unique. In his presidential address on the occasion 

 referred to, which is fully reported in the April number of the 

 Essex Naturalist, Prof. Meldola summarises the scientific work 

 of the Society ; and it is a record of which the Society may well 

 be proud. In many respects Essex is a county offering pecu- 

 liarly favourable opportunities for local scientific research. It 

 has a large seaboard, in common with Suffolk, it contains 

 deposits of " Red Clay," the brick-earths of Ilford and elsewhere 

 teem with remains of Pleistocene mammals, and prehistoric 

 and other ancient works of man abound within its limits. 

 Moreover, in Epping Forest it possesses a tract full of interest 

 alike to the naturalist and the antiquarian. To the workers in 

 all the branches of local scientific research the president does 

 full justice. 



In the Jahrbttch der k.-k. geol. Rcichsanstalt, Band li., 

 Heft I (1901), Dr. O. Abel contributes a very interesting paper 

 on some curiously marked pebbles from the Algerian Sahara. 

 The pebbles, as the result of exposure to desert erosion, possess 

 a characteristic surface sculpture of ridges and furrows, which 

 have a more or less regular radial disposition. The special 

 interest of this character lies in its wonderfully close resemblance 

 to the sculpture frequently exhibited by moldavite, made more 

 particularly familiar to us through Dr. F. E. Suess's advocacy 

 of the meteoric origin of this mineral. The sculptured pebbles 

 dealt with in this paper are of discoid form, and radial furrows 

 are impressed on both sides of the disc. At the periphery the 

 furrows become more plainly marked, and tend to pass .icross 

 the margin of the disc in a direction at right angles to the tlat- 

 NO. 1695, VOL. 65] 



tened surfaces. The author examines the possible causes of this 

 curious sculpture, and concludes that the ordinary action of the 

 wind, driving sand-grains against the motionless pebljes, would 

 be quite inadequate to produce the stellate figures on opposite 

 surfaces of the stone. He believes, however, that the natural 

 sand-blast is, in fact, the true eroding agent, but that the pebbles 

 were rotating when attacked by it, while raised from the ground 

 and driven forward over the surface of the desert during repeated 

 sand-storms. That the stellate sculpture would result from such 

 agencies the author considers to be proved by certain experi- 

 ments carried out by Dr. F. E. Suess, to which he refers. As 

 regards the analogous sculpture of moldavite, the author suggests 

 that it might also have been produced by the prolonged exposure 

 of the moldavite fragments to desert conditions, an idea which 

 is supported by the form and size of the moldavite specimens, 

 as well as by the relative softness of this glass when compared 

 with quartz sand. At the same time, he considers that the 

 theory of the cosmic origin of moldavite is in no way weakened 

 by such a conclusion. The paper is excellently illustrated. 



The University of Texas Mineral Survey, under the direction 

 of Mr. \V. B. Phillips, has issued a report on sulphur, oil and 

 quicksilver in Trans-Pecos (Bulletin, No. 2, 1902). In the 

 Cretaceous area in Texas both heavy and illuminating oils are 

 found at no great distance from each other. The subject was 

 dealt with in Bulletin No. I ; some further particulars are now 

 given, and complete analyses of all the coals, lignites and asphalt 

 rocks, together with tests of the fuel value of the different oils, 

 are in preparation. Quicksilver ores, chiefly cinnabar, occur in 

 Brewster county in hard Cretaceous limestone and in decomposed 

 shale, the rich stringers and pockets of cinnabar being found 

 along bedding-planes and in cracks of the limestone associated 

 with shaly matter. Intrusions of dolerite occur near by, and 

 with them are probably connected the disturbance of the strata 

 and the deposition, most likely from aqueous solution, of the 

 metallic impregnations. Important sulphur deposits are met with 

 in El Pasco county, and it is considered that 300,000 tons are 

 available within forty feet of the surface in the vicinity of 

 Maverick Springs. The area is described as consisting of a 

 white plain of gypsum with a few small hills upon it, those on 

 the west of gypsum, and those on the east of more recent con- 

 glomerate and white dolomite. The beds of gypsum overlie 

 Upper Carboniferous sandstones and shales and are probably of 

 Permian .age. Throughout the tract sulphur springs are common, 

 sulphur occurs in various forms, and the soil in places contains 

 as much as 5 per cent, of free sulphuric acid. The gypsum beds 

 are from 300 to 500 feet thick, and^sulphur occurs in small crystals 

 embedded in white gypsum, sometimes to the extent of 25 per 

 cent. Elsewhere the sulphur occurs as a bluish ore in a siliceous 

 earthy gangue, yielding 70 per cent, of sulphur. The matrix is 

 locally bituminous, and it is noted that in all localities there are 

 signs of oil. From a careful study of the subject, Mr. B. M. 

 Skeats is of opinion that the richer bluish ores were formed from 

 sulphur waters at a time when they were above ground, and 

 probably through the agency of certain algoe which are plentiful 

 in the sulphur springs today. All the sulphur occurs in and 

 with gypsum and in connection with water containing sulphur* 

 etted hydrogen. The ores in which the sulphur occurs as 

 crystals were probably formed by the decomposition of sulphur- 

 etted hydrogen given off from the highly charged water when it 

 entered a porous or broken stratum. It is further considered that 

 the gypsum may have been at one time carbonate of lime, for 

 in many places it is difficult to say where limestone ends and 

 gypsum begins. 



While we have large engineering workshops all over the 

 country supplying machinery for practical use, it is with interest 

 we note that a journal dealing with model making on a very 



