53« 



NATURE 



[February 15, 191 2 



currents of considerable magnitude by what appears to be 

 a now method. Two insulated carbon electrodes are 

 inserted into a carbon tube resistance furnace at high 

 temperatures, and are connected externally through a suit- 

 able current-measurer. If one of the electrodes is suddenly 

 displaced to a colder or hotter part of the furnace, a 

 reversible transient current is produced in the circuit with- 

 out the application of any external potential. By such 

 means, currents up to 2 amperes have been obtained. The 

 production of an alternating cUrrent is thus rendered 

 possible by the use of a suitable periodic device. A con- 

 tinuous current can be generated by suitably modifying 

 the apparatus so as to maintain a large permanent tempera- 

 ture-difference between the electrodes. A steady current of 

 08 ampere has been thus obtained for a few minutes, and 

 o-i ampere for more than an hour by water-cooling one 

 electrode. These currents are such as would be produced 

 by a discharge of negative particles from the hot electrode. 

 At the lower temperatures positive currents have also been 

 detected, but of much smaller magnitude. All the observa- 

 tions were made at atmospheric pressure. The extent of 

 the ionisation of the furnace atmosphere at high tempera- 

 tures was such that quite small E.M.F.'s, applied to two 

 exploring electrodes, gave rise to steady currents of rela- 

 tively enormous magnitude. For example, with 8 volts, 

 currents up to 10 amperes have been obtained at a tempera- 

 ture of about 2500° C. Some of these observations have 

 been repeated with furnaces of a non-electric character.— 

 Prof. H. T. Barnes : The so-called thermoid effect and 

 the question of superheating of a platinum-silver resistance 

 used in continuous-flow calorimetry. — Prof. E. G. Coker : 

 •An optical determination of the variation of stress in a 

 thin rectangular plate subjected to shear. The distribu- 

 tion of stress in a rectangular plate subjected to shear is 

 examined by observing the optical effects in polarised light 

 produced in a stressed plate of xvlonite. Measurements of 

 the shear stress at a point are obtained bv using a speci- 

 men of material similar to the plate, and set along the 

 direction of principal compression stress. A tension load 

 IS applied to this member of sufficient amount to produce 

 a dark field at the point under examination. The intensity 

 of tension stress so produced is twice the density of the 

 shear stress in the plate. A survev of the central longi- 

 tudinal section of a long rectangular plate shows that the 

 shear stress rises very rapidly from a zero value at the 

 ends, and reaches a maximum at a distance of rather 

 less than the face width of the plate. As the distance 

 from the ends increases, the stress decreases slightly in 

 value until it reaches a minimum at the centre. A similar 

 distribution also occurs at sections parallel to the central 

 line. As the length of the plate is diminished the maxi- 

 mum and minimum stresses become more pronounced, and 

 when the ratio of length to width is in the neighbourhood 

 of two, the distribution changes in such a manner that 

 there is a maximum at the centre. It is shown that the 

 distribution is approximately parabolic when the length 

 IS equal to the width of the plate, and that when the 

 length IS greater than this the approximation is less close. 

 The experiments show that a parabolic distribution of 

 shear is only true within narrow limits, and that in a 

 long rectangular section the distribution may be approxi- 

 mately represented by a uniform shear over the central 

 section with a rapid fall towards the ends.— Dr. P. V. 

 Bevan : Spectroscopic observations : lithium and caesium. 

 Captain C. F. U. Meek : A metrical analysis of chromo- 

 some complexes, showing correlation between evolutionary 

 development and chromatin thread-widths throughout the 

 animal kingdom. Measurements of chromosomes in 

 organisms representing the principal phvla and classes of 

 the animal kingdom have shown that lengths appear to 

 constitute members of a series in arithmetical progression, 

 whereas three distinct diameters exist, viz. 0-21 fx. in 

 Protozoa, and 0-42 /u and 083 (x in low and higher meta- 

 zoan phyla respectively. Consideration of these results 

 has suggested the following working hypothesis :— The 

 chromatin granules of simplest Protozoa are a visible ex- 

 pression of differentiation and aggregation of specialised 

 particles concerned with transmission of hereditary 

 characters, and as such probably do not represent the sole 

 bearers of heredity in the cell. 'The granules become con- 

 verted into rods by purely linear growth accompanying 



NO. 2207, VOL. 88] 



evolutionary development and greater somatic compi' 

 and, since the rate of growth is not the same i^ 

 chromosomes, rods of various lengths are evolved 

 stage in phylogeny is later reached when a maximun 

 length has been attained, such limit being in^: 

 spindle mechanism or other physical conditions ; 

 occurs, chromatin units conjugate in fours, and th<- m 

 thread-width is thus doubled. The newly formed chf 

 somes then segment into spheres of the same dian. 

 and these are prepared to enter a new course of 1 

 growth accompanying further development. The - 

 process is repeated when the length-limit has again 

 reached, and in this manner the greatest thread-width 

 evolved. The absence of correlation between chrome 

 dimensions and somatic characters is explicable on 

 an assumption, which postulates a series of cycles in' 

 course of phylogeny. The heterotropic chromosome ai 

 does not belong to the general series, and its great bre 

 may eventually be shown to be due to conjugation 

 normal rods ; it is probably undergoing some process 

 development or disintegration, and may or may not 

 the determining factor in sex. 



Linnean Society, Fehruaiy i.— Prof. E. B. Poultct 

 F.R.S., vice-president, in the chair. — Fauna of 

 Seychelles and other islands of the Indian 

 (i) \. Porel : Fourmis des Seychelles et des .Mdat 

 revues de M. Hugh Scott. (2) F.' W. Edwards : Tipul 

 (j) Dr. Giinther Enderlein : Sciaridae. (4) Cla« 

 Morley : The Ichneumonidae. (5) C. Tate Rearan : N« 

 fishes. 



Matbema'ical Society, February 8.- Dr. II. F. Bak« 

 F.R.S., president, in the chair. — .'\. C. Dixon : Exceptions 

 to extensions of a theorem of Jacobi's. — W. Burnside : 

 Some properties of groups whose orders are powers of 

 primes. — G. H. Hardy and J. E. Littlewood : Som« 

 results concerning diophantine approximations. 



Malacological Society, Fehruar)' 9. — R. Bullen 

 Ne\Mton : Presidential address: "On the Lower Tertiary 

 Mollusca of the Fayum Province of Egypt." The presi- 

 dent referred to the discussion among writers on vertebrate 

 palaeontology as to the age of the Palaeomastodon beds 

 occurring near the base of the Jebel el Qatrani deposit*, 

 in the north of the Fayum depression of Egypt. Such bedt 

 were regarded by Mr. Beadnell and Dr. C. \V. .Andrews a». 

 Bartonian, whereas Prof. Dep^ret and others had assigned 

 them to the Sannoisian-Stampian division of the Oligocene 

 period. Instead of regarding them as younger, Mr. 

 Newton was of opinion that they might even be older, and . 

 he was much in favour of recognising the beds as belong* 

 ing to the Lutetian-Bartonian stage of the Eocene, since 

 the associated genera Moeritherium, Podocnemis, and 

 Stereogenys occurred alike in these beds as well as in the 

 Qasr el Sagha deposits below, which are undoubtedly of 

 Lutetian or Middle Eocene age. Certain estuar'"** 

 Mollusca, particularly Potamides scalaroides and P. 

 iriatus, occurred high up in the Jebel el Qatrani sec: 

 and some 150 metres above the Palaeomastodon bed; t: 

 gastropods have been determined by Dr. Blanckenhon 

 indicative of the Bartonian horizon, and are therefore 

 clusively against the view that the vertebrates belont; 

 the younger period of the Oligocene. Mr. Newton - 

 ported these molluscan determinations, and, moreover, 

 held Dr. Blanckenhorn's opinion that the species v 

 characteristic of the " Beauchamp Sands " of the P 

 Basin, and consequently belonged to the older part of 

 Bartonian horizon. 



Paris. 



Academy of Sciences, January 29. — M. I ippmanr 

 the chair. — The president read a letter from Prince Ro' 

 Bonaparte giving a donation of 35,000 francs to the Fr^ 

 School of Medicine at Beyrout. — G. Bigrourdan : An 

 published work of Delambre, " Grandeur et figure d' 

 Terre." — A. Lacroix : Lavas from the active volcano "t 

 Reunion. Complete chemical analyses are given of 

 thirteen lavas, and a discussion of the results. — <"'■• 

 Andrd : The total eclipse of the moon of November 

 iqio. The positions of three uncatalogued stars, ref'^: 

 to in the author's previous note on the eclipse, are gi 

 — Hildebrand Hildebrandsson was elected a corresponc: 

 for the section of geography and navigation in the p' 



