March 4 «909] 



NATURE 



iind science, the office of sub-dean has been created to 

 provide greater facilities for giving students advice. The 

 organisation of the arrangements for post-graduate courses 

 and for research has been improved. The report contains 

 lists of original papers that have been issued during the 

 past voar. The activity of the department of applied 

 mathematics, under Prof. Karl Pearson, including the 

 (lalton Laboratory for National Eugenics, is marked by 

 the issue of twenty-seven publications, and that of the 

 department of chemistry, under Sir William Ramsay and 

 I'rof. J. Norman Collie,' by the publication of forty original 

 papers. The report closes with a summary of the urgent 

 needs of the college. The need for new buildings for the 

 department of chemistry, at a cost of about 70,000!., is 

 placed in the forefront. The Chancellor, the Earl of Rose- 

 bcry. has intimated his willingness to subscribe loooi. to a 

 fund for the erection of new chemical laboratories. The 

 oxpenditure for the year was 53,535'. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, December 10. 1908. — "'The Roiaiion 

 <il ih' Electric Arc in a Radial Magnetic Field." By J. 

 Nicol. Communicated by Prof. H. A. Wilson, F.R.S. 



It is well known that the electric arc is deflected by a 

 tr.insverse magnetic field. If the electrodes are tubular 

 and the field is radial, spreading from an iron rod lying 

 along the axis of the electrodes, the arc will travel round 

 these continuously. If 7c, and /;, are the velocities, due to 

 unit electric force, of the ions carrying the charge, the 

 transverse velocity of the arc is fe,fcjHX, so that a measure- 

 nif-nt of this velocity will give the product /c,/c,. 



The measurement was made by placing a slit in front 

 of the arc and allowing the light passing through this 

 to fall on a rotating mirror, which reflected it into a 

 photographic camera. The axis of rotation of the mirror 

 almost coincided with the normal to its surface, and this 

 caused the image of a point source to be a small circle. 

 .As the slit was only illuminated intermittently (once during 

 each revolution of the arc) the image on the plate con- 

 sisted of a number of dots arranged round a circle. Count- 

 ing these enabled the velocity of the arc to be determined. 



Copper arcs I.8-3-6 mm. long, carrying currents from 

 2-g amperes, were used. The magnetic field varied from 

 35—140 C.G.S. units, and the resulting arc velocities from 

 200-1100 cm. per sec. 



The results of the experiments led to the formula 

 ^ = H(2-5S-l-074t) 

 connecting the velocity with the magnetic force and arc 

 current. The values deduced for fe.fe, lie between 

 0-53x10' cm. per sec. per volt per cm. for a two-ampere 

 arc and 1.5x10' for nine amperes. 



Langevin has given an expression for fe in terms of the 

 mean free path, and the agitation velocity of the particle 

 /.• = cA/mu. 



This gives k for a corpuscle 1.83x10*, and this, combined 

 with the experimental result 10' for fe,fe;, gives 5-5x10- 

 as the velocity of the positive ion. Since mir is the same 

 for all gases, Langevin's expression shows that kxif^m. 

 Hence in the arc the positive ion is 900 times as heavy 

 as a corpuscle. This mass is about the same as that found 

 by Sir J. J. Thomson for the positive ions in the Kanal- 

 strahlen, but much less than that of the atoms (Cu, N, or 

 O) present in the arc. 



February 11. — Sir .Archibald Geikie, K.C.B., president, 

 in the chair. — The nerves of the atrio-ventricular bundle ; 

 J. Gordon Wilson. In the introduction the author refers 

 to the discovery of this muscular bundle and its func- 

 tion by Gaskell, also to the valuable work of his and 

 the important research of Tawara upon the structure of 

 this bundle. He points out that both Tawara and Retzer 

 m.ide definite statements of the existence in the bundle 

 of nerve cells and fibres. The material used for this re- 

 search was obtained from the pig, calf, and sheep ; the 

 terhniciue employed was the methylene blue " vital " 

 method. Conclusions : — I. Anatomically, the atrio-ventri- 

 cular bundle contains, not only a special form of muscle 

 fibrr- distinct from the ordinary muscle of the atrium or 



NO. 2053, VOL. 80] 



the ventricle, but also an important and intricate nerve 

 pathway, in which we find : — (i) numerous ganglion cells. 

 monopolar, bipolar, and multipolar, the processes of which 

 may pass (o) to adjacent ganglion cells in the bundle, 

 (6) to the muscle fibres in the bundle, and (c) through the 

 muscle bundle so far as it was examined ; (2) abundant 

 nerve fibres running through it in strands, the processes 

 of which may end (a) in ganglion cells in the bundle, 

 (6) in the muscle ple.xus, or pass through the part ex- 

 amined ; (3) an intricate plexus of varicose fibrils around 

 and in close relation to the muscle fibres of the bundle ; 

 (4) an abundant vascular supply with well-marked vaso- 

 motor nerves and sensory endings. II. Physiologically it 

 has' been shown that the atrio-ventricular band constitutes 

 ihe pathway which assures the communication of the 

 atrio-ventricular rhythm. When the bundle is sectioned or 

 crushed, the ventricles cease momentarily to beat, though 

 they soon regain pulsation, but with a rhythm much more 

 slow than that of the atrium. Pathological anatomy sup- 

 ports this view ; the allorhylhmia of Stokes-Adams disease 

 can be explained satisfactorily by lesions involving this 

 pathway. As a result of these physiological experiments, 

 and from these pathological conditions, it has been asserted 

 I hat the contraction wave must be myogenic. To such a 

 deduction the author's anatomical findings are opposed. 

 They demonstrate that in these experiments and patho- 

 logical conditions an important nerve pathway is equally 

 involved with the muscle bundle. — -An experimental 

 estimation of the theory of ancestral contributions in 

 heredity : A. D. Darbishire. The modern experimental 

 study of (bi-parental) inheritance is based on the assump- 

 tion that the character of an organism is determined by 

 the potentialities existent in the germ cells which pro- 

 duce it, and not by the nature of the parents of that 

 organism or of its more remote ancestors. In other words, 

 according to the former view, the attempt to predict the 

 result of a given mating must be based on some theory 

 as to the characters existent potentially in the germ cells 

 of the two individuals mated, and the characters of the 

 parents themselves and of the remoter ancestry may be 

 left out of account altogether in the attempt to make this 

 prediction. The present paper gives an account of an 

 experiment designed to decide, in regard to a particular 

 character, between these two fundamentally different 

 theories. The result of a cross between a yellow-seeded 

 pea and a green-seeded pea, both of pure race, is already 

 well known. All the first generation (F,) are yellow, and 

 25 per cent, of the next generation (FJ, produced by 

 mating these yellow hybrids inter se, are green, the rest 

 being yellow. These " e.xtracted " greens, as they are 

 called, are said to be produced, by the yellow hybrids, in 

 the same proportion, in each successive generation (Fj, 

 F^, . . . &c.), according to a scheme which it is not neces- 

 sary to give here. An extracted green in F^, therefore, 

 has a great " weight " of yellow ancestry behind it, 

 inasmuch as no green appears in that ancestry nearer than 

 the great-great-great-grandparental generation, whilst 

 behind that half the ancestors are yellow and half green. 

 The author has made a number of crosses between pure 

 vellow strains and extracted greens in F5. All the (F,) 

 hybrids thus raised were yellow, as might have been 

 expected. With regard to the next generation, however, 

 it is evident that if there is any truth in the view that 

 the characters of the parents and ancestors play any part 

 in determining the composition of a given generation, less 

 than 25 per cent, green should occur in F, from this cross. 

 No such result is obtained. The proportion of greens in 

 F, is 24-88 per cent., the number of greens being 34,792 

 and of yellows 105,045. The probable error of the per- 

 centage is ±0-078. The actual deviation from the 25 per 

 cent, expected, namely, 0-12 per cent., is not twice the 

 probable error, and is therefore certainly not significant. 

 —The determination of a coefficient by which the rate of 

 diffusion of stain and other substances into living cells 

 can be measured, and bv which bacteria and other cells 

 may be differentiated : H. C. Rosa. When fresh blood is 

 spread upon a film of agar jelly which contains Unna's 

 stain and certain salts, the stain diffuses into the living 

 cells, and the rapidity of diffusion depends on certain 

 factors. It is accelerated by heat, and, of course, by time. 

 If the jellv is alkaline, diffusion is also accelerated. .Acids 



