May II, 1893] 



NA TURE 



47 



from Dorset (where Mr. C. B. Clarke had seen it growing on 

 Poole Harbour Spit though it had not been included hitherto 

 in the county flora), and Scilla nutans with prolonged bracts, 

 usually regarded as an introduced garden form, which had been 

 found growing apparently wild in a wood near Ashford, Kent. 

 — Mr. Alfred Sanders then read a paper on the nervous system 

 oi Myxine gUttinosa, a fish allied to the Lampreys, 



Dublin. 



Royal Dublin Society, April 19. — Prof. A. A. Ram- 

 baut. Astronomer Royal for Ireland, in the chair.— Dr. J. 

 Joly, F.R. S., described a method of detecting the existence 

 of variable stars by continuous photometric observations from 

 night to night on groups of stars, by receiving the image of the 

 group upon a photographic plate having a slow eccentric 

 circular motion within the telescope, so that the images of the 

 individual stars appear as circular traces upon the plate. 

 Variations in the intensity of any trace, not common to all the 

 linear images, indicate a variability of luminosity in the parti 

 cular star describing the trace. — Prof. A. A. Rambaut read a 

 paper on the distortion of photographic star images due to 

 refraction. — The usual formulae of refraction by which the rela- 

 tive position of one star with regard to another may be corrected 

 for this effect, such as those published lately by the author in the 

 Astronomische Nachrichteii, No. 3125, are strictly applicable 

 only to one definite instant of time. It is possible to keep only 

 one star absolutely fixed on the plate by means of the slow 

 motions in R. A. and declination, and the changes in the amount 

 of the differential refraction will cause any other star to alter its 

 position on the plate if the exposure is continued for any con- 

 siderable time. The effect of this change is that all stars on 

 :he plate, except that used to guide by, are more or less dis- 

 torted. The paper contains tables giving the amount by which 

 the refraction changes at various declinations and hour angles, 

 and from these the amount by which a star image on the plate 

 is distorted in passing from any hour angle to any other can be 

 readily computed. For instance, it is shown that an equatorial 

 star whose distance and position angle from the guiding star are 

 1400" and 45° would, in passing from an hour angle of 4h. to 

 one of 5h., be distorted in R. A. by 5" '86 and in declination by 

 7"'98. It appears, however, that if the zenith distance does 

 not exceed 60' and the exposure is limited to a quarter of an 

 hour, the distortion will not exceed o"'2, and that if the correc- 

 tions are computed for the middle of the exposure and the 

 measures made from the middle of the slightly distorted image 

 no error will arise. — Prof. T. Johnson, exhibited Gomoutia 

 folyrhiza. Born, et Flah., a green alga, perforating the shells of 

 various molluscs. Specimens were collected at different 

 localities on the west and east coasts of Ireland ; Galway (April, 

 1891) being the first locality in which the plant was observed. 



Paris. 

 Academy of Sciences, May i. — M. Loewy in the chair. — 

 The motion of liquids studied (by chronophotography, by M. 

 Marey. The water whose motion was to be studied was con- 

 tained in a long tank bent into an elliptic shape and returning 

 upon itself. One of the branches had both sides closed by 

 panes of plate glass, behind which was placed a screen of black 

 velvet. .\ centimetre scale was fixed to the inner pane, and the 

 tank was illuminated by sunlight reflected from below. The 

 camera was placed at a distance in front of the glass, screens 

 being arranged so as to keep off all light except that coming 

 -from the water. When the water was clear, the only thing 

 photographed was the meniscus formed by its surface against the 

 glass, which appeared as a bright straight line. When the sur- 

 face was disturbed by waves, the nature of the disturbance was 

 indicated by the successive shapes assumed by the meniscus. To 

 study the internal motions of the liquid, small globules were 

 constructed of wax and resin, silvered like certain pills, and so 

 proportioned as to be slightly heavier than water, so that they 

 could be made to float in neutral equilibrium by adding salt 

 water. Stationary waves were then produced by rapidly chang- 

 ing the immersion of a solid cylinder on the opposite side of the 

 tank, when the meniscus was thrown into the species of trochoi- 

 dal curve already deduced from hydrodynamical theory. This 

 curve appears in the photographs in great perfection. A wave 

 of translation was also photographed fourteen times per second, 

 and its velocity, as calculated by the scale, was 2 '24 m. per 

 •second. Streams and eddies were also produced in the tank, 

 •and traced by means of the bright balls. On letting the water 



NO. 1228, VOL. 48] 



flow past an obstacle in the form of a fish, more obtuse on one 

 side than on the other, it was proved that no perceptible eddies 

 were formed if the water first encountered the obtuse side, but 

 that it was greatly disturbed if the acute end was presented to 

 the stream. — Determination of the specific heat of boron, by 

 MM. Henri Moissan and Henri Gautier. — On mineral phos- 

 phates of animal origin, and on a new type of phosphorites, by 

 M. Armand Gautier. — On the sanitary system adopted by the 

 Dresden Conference for establishing common measures to safe- 

 guard the public health in times of epidemic cholera, without 

 placing useless obstacles in the way of commercial transactions 

 or the movements of travellers, by M. Bronardel. — Observations 

 of the comets. Brooks (1892, VI.), Holmes (1892, III.), and 

 Brooks (1893, I.), made with the great equatorial of Bordeaux, 

 by MM. G. Razet, L. Picart, and F. Courty. — On a general 

 case where the problem of the rotation of a solid body admits of 

 uniform integrals, by M. Hugo Gylden. — On the displacement 

 of the temperature of maximum density of water by pressure, 

 and the return to the ordinary laws under the influence of pres- 

 sure and temperature, by M. E. H. Amagat. — Researches to 

 establish the bases of a new method of recognising the adultera- 

 tion of butter by margarine employed either singly or mixed 

 with other fatty materials of vegetable or animal origin, by M. 

 A. Houzeau. — Observation of the solar eclipse of April 16, 

 1893, at the observatory of the Societe Scientifique Flammarion 

 at Marseilles, by M Leotard. — On a class of differential equa- 

 tions, by M. Vessiot. — On the structure of finite and continu- 

 ous groups, by M. Cartan. — On the ordinary differential equa- 

 tions which possess a fundamental system of integrals, by M. 

 A. Guldberg. — On the reduction of the problem of tantochronics 

 to the integration of a partial differential equation of the first 

 order and the second degree, by M. G. Kcenigs. — On the densi- 

 ties and molecular volumes of chlorine and of hydrochloric acid, 

 by M. A. Leduc. — On the diminution of the coefficient of 

 expansion of glass, by M. L. C. Baudin. — On the systems of 

 dimensions of electrical units, by M. E. Mercadier. — On the 

 influence of longitudinal magnetisation upon the electromotive 

 form of a copper-iron couple, by M. Chassagny. — Optical phe- 

 nomena presented by secondary wood in thin sections, by M. 

 Constant Houlbert.— Decomposition of oxalic acid by the ferric 

 salts under the influence of heat, by M. George Lemoine. — Con- 

 tribution to the study of the Leclanche cell, by M. A. Ditte. 

 On the fluorides of the alkaline earths, by M. C. Poulenc. — On 

 the quantitative determination of phosphoric acid, by MM. A. 

 Villers and Fr. Borg. — On licarene derived from licareol, by 

 M. Ph. Barbier.^On a vegetable nucleine, by M. P. Petit. On 

 an earthquake shock felt at Grenoble on April 8, by M. 

 Kilian. — The month of April, 1893, ^'i ^I- E. Renou. — On the 

 emission of a sugar-containing liquid by the green parts of the 

 oranje-tree, by JL E. Guinier. — On a new genus of conifers 

 found in the Albian of the Argonne, by M. Paul Fliche. — Dis- 

 covery of two skeletons at Villejuif and at Thiais, their age 

 and ethnic character, by M. Zaborowski. — Periodic form of the 

 doriferous power in the fatty series, by M. Jacques Passy. — 

 Researches on the employment of tree leaves in the feeding of 

 cattle, by >I. A. Ch. Girard. 



Berlin. 



Physiological Society, April 7. — Prof, du Bois Reymond, 

 President, in the chair. — Dr. Engel gave an account of the out- 

 come of his researches on the development of blood corpuscles. 

 By using appropriate staining reagents, and fixation of the cor- 

 puscles by drying, he had found, in the embryos of mice in 

 various stages of development and in leukhsemic children, that 

 at first spheroidal nucleated cells make their appearance, metro- 

 cytes, which subsequently divide karyokinetically into daughter- 

 metrocytes. From the latter some non-nucleated cells contain- 

 ing haemoglobin are developed, as also some red-coloured cells, 

 from which are then formed the red corpuscles, the nucleated 

 white corpuscles and platelets. In the discussion which ensued 

 Prof. Ehrlich confirmed the above results from personal obser- 

 vations, but regarded the origin of white blood-corpuscles from 

 the red cells as not yet definitely established. Prof. Kossel 

 spoke on a new saccharine substance called Dulcin, describing its 

 chemical constitution and its effect on rabbits and dogs. Dulcin 

 is two hundred times as sweet as sugar. Rabbits were unaffected 

 by daily doses of 2 grm. (= 400 grm. sugar), but dogs were 

 found to lose their appetite by prolonged taking of the above 

 dose, recovering it soon when the drug was no longer adminis- 

 tered. Prof. Ewald had tried the effect of dulcin upon both 



