2o6 



NATURE 



[April 24, 19 13 



notably, the tartrates, which was given by Biot, the 

 original discoverer of optical rotatory power, viz. that 

 it may be due to the presence of two compounds of 

 opposite rotatory power (+ and — ) differing in rota- 

 tory dispersive power. This explanation appears to 

 have been generally overlooked. The behaviour to 

 be expected of compounds varying in their optical 

 pi operties in different ways is discussed. The results 

 arrived at serve to explain the apparently abnormal 

 variation in optical behaviour often noticed in optic- 

 ally active compounds; they also appear to be of 

 significance as indicating a relation among 

 generally and underlying their action towards sub- 

 stances generally of a very definite and regular char- 

 acter; each solvent would seem to have its definite 

 sphere and mode of action, so that any two solvents 

 behave relatively always in the same way towards 

 solutes generally, apart from the exceptional cases in 

 which some special property of the solute comes into 

 operation to disturb regularity of action. 



Geological Society, April 9.— Dr. Aubrey Strahan, 

 F.R.S., president, in the chair. — Dr. G. Hickling : 

 The variation of Planorbis multiformis, Bronn. The 

 writer gives an account of an investigation of the 

 above-named Miocene gasteropod, based on a suite of 

 532 specimens from a single block of stone. A study 

 was made of the variation in height presented by 

 the shells, which include every gradation between 

 perfectly discoid forms and types with a spire the 

 height of which considerably exceeds the diameter of 

 the base. By sorting the whole of the shells into ten 

 grades, according to height, it was shown that forms 

 of mean height were common, while extreme forms 

 were rare, the height being distributed, in fact, 

 according to a typical "variation-curve." If more 

 than one species were really present, it is in the 

 highest degree improbable that the various types 

 should be distributed in the proportions actually 

 found, and this is taken as the most satisfactory 

 proof possible of the specific unity of the group. It 

 is shown that the shells also varv extensively in re- 

 spect of the amount of carination, the degree of in- 

 volution, the form of cross-section of the whorls, the 

 form of aperture, and the stage of development at 

 which various characters are acquired, the variation 

 in each character being, however, "continuous." — 

 Mis, M. Colley March: The structure and relation- 

 ships of the Carbonicolse. The evidence for the rela- 

 tionship of the Carbonicolas to the Unionida?, based 

 on shell-structure, muscle-scars, form, habitat, liga- 

 ment, and hinge-teeth, appears insufficient. 



Physical Society, April 11.— Prof. C. H. Lees, F.R.S., 

 vice-president, in the chair. — A. Campbell and H. C. 

 Booth : Errors in magnetic testing due to elastic 

 strain. In magnetic tests on sheet material consider- 

 able errors may occur if the sheets or strips are tested 

 while in bent form. These errors, which are in 

 general agreement with the known effects of com- 

 pression and tension, were investigated experimentally 

 with one or two forms of magnetic circuit similar 

 to those sometimes occurring in practice. — Dr. 

 G. W. C. Kaye : Note on kathodic sputtering. The 

 paper gives an account of the volatilisation of an 

 aluminium kathode in a discharge tube containing 

 helium. The sputtered deposit on the glass indicates 

 that, under the conditions which prevailed, the dis- 

 integration was restricted to the edges of the kathode 

 and did not occur elsewhere. Accordingly the com- 

 plete outline of the kathode (made by rolling a sheet 

 of aluminium into a nearly complete cylinder! was 

 traced out bv the deposit on the walls of the tube.- 

 A. Campbell : Vibration galvanometers with unifilar 

 torsional control. The author exhibited a moving-coil 

 XO. 226g, VOL. 91] 



vibration galvanometer in which a novel principle is 

 used to obtain the fine adjustment of the control 

 torque requisite for accurate tuning. 



Dublin. 

 Royal Dublin Society, April 15. — Dr. James H. Pollok 

 in the chair.— Prof. H. H. Dixon and W. R. G. 

 Atkins : Extraction of zymase by freezing. Yeast 

 frozen solid by exposure to liquid air, and centrifuged 

 when thawed, gives up its sap. The sap thus ex- 

 tracted amounts to about one-third of the volume of 

 the yeast originally treated. It is free from ferment- 

 able carbohydrates, but actively ferments cane-sugar 

 when supplied to it. Its activity, in the samples 

 examined, was as great as that of the extract prepared 

 from the same samples by Lebedeff's maceration 

 method. The method of extraction by means of liquid 

 air has the advantage of great rapidity. Culture ex- 

 periments show that the yeast is killed by exposure, 

 to the temperature of liquid air. — Prof. H. H. Dixon 

 and \V. R. G. Atkins : Osmotic pressures in plant 

 organs. III., The osmotic pressure and electrical 

 conductivitv of yeast, beer, and wort. Measurements 

 of osmotic pressure were made by the thermo-electric 

 method of cryoscopy previously described. The yeast 

 juice was obtained by freezing the yeast in liquid air 

 and centrifuging the resultant liquid mass. It was 

 found that ordinary yeast has an osmotic pressure of 

 about 41 atm., that of wort being about 14. Thus 

 there is a marked rise in pressure during fermenta- 

 tion. The impermeability of the yeast cell to electro- 

 lytes is shown bv the conductivity of the juice being 

 about four times as great as that of the beer, which 

 is practically the same as that of the unfermented 

 wort. Both the osmotic pressure and electrical con-, 

 ductivity of pressed yeast are greater than is the case 

 in actively fermenting yeast. — R. Lloyd Praeger : The 

 buoyancy of the seeds of some Britannic plants. The 

 importance of the question of the buoyancy of seeds 

 in water in connection with the dispersal and distribu- 

 tion of plants has been long recognised. The experi- 

 ments of Darwin, Martins, Thuret, and Guppy lead to 

 the generalisation that only about one-tenth of a flora 

 bear seeds capable of more than a very brief period 

 of buoyancy. The present experiments were under- 

 taken in order to furnish further data for a study of 

 the dispersal of our native species. Hitherto results 

 were available for about 330 native species. The 

 number of species tested is now raised to 900. The 

 results bear out the conclusion already mentioned ; 

 also Guony's conclusion that the buoyant seeds belong 

 mainly to maritime and marsh species. Some results 

 relating to fresh and dried fleshy fruits and also to 

 fruiting branches are given. 



Paris. 

 Academy of Sciences, April 14. — M. F. Guyon in the 

 chair. — Emile Picard : Application of the theory of in- 

 tegral equations to certain problems in the analytical 

 theory of heat on the hypothesis of a sudden rise of 

 temperature al tin surface of separation of the bodies 

 in contact. — J. Boussinesq : The velocity of slow fall of 

 a liquid spherical drop, after becoming uniform, in a 

 viscous liquid of slightly greater density than the 

 falling drop. - M. I.andouzy was elected a member of 

 the section of free academicians in the place of the 

 late M. Teisserenc de Bort. — G. de Saint-Aubin : An 

 apparatus allowing of a variation of the carrying sur- 

 face of an aeroplane. The apparatus consists of two 

 auxiliary planes with surfaces of slight curvature, 

 with their centres of sustentation for a given angle 

 of attack on the same line passing through the centre 

 of sustentation of the ordinary planes of the aeroplane. 

 J. Guillaume : Observations "of the sun made at the 



