March 7, 1889] 



NA TURE 



453 



a result which has long been known for a stream-line, but, ap- 

 parently, not so long known for a vortex-line. It holds also 

 for an infinite number of curves that can be drawn through 

 P, all lying on a certain surface, as is pointed out by Lamb 

 ("Motion of Fluids," p. 173), the surface in question being 

 formed of a network of stream- and vortex-lines. That such 

 surfaces exist in the fluid when the external forces have a poten- 

 tial, is proved most satisfactorily by taking the integral of (a) 

 along a circuit through P, of which a part consists of stream-line 

 and a part of vortex-line ; but into the details of this we need 

 not enter. 



I observe, also, that this equation (2) holds for the portion of 

 any curve whatever connecting any two points, A, B, on a 

 network surface, although this curve does not lie on the surface. 



Another point to which I would call attention is an analytical 

 expression of the state of non-vortical motion. The physical 

 expression has, of course, reference to the non-rotation of the 

 three principal axes of the little ellipsoid into which, at each 

 instant, a small sphere is deforming. The analytical expression 

 of the fact takes usually the form that there is a velocity poten- 

 tial, i.e. = , with two Cartesian analogues. Here, again, 



I would suggest a single equation, having no reference to special 

 axes. This equation is simply 



(S) 



where s and a denote arcs of any two curves whatever drawn at 

 the point P, and i and a the component velocities of the fluid 

 along them. 



It is obvious that these contain the whole three of the usual 

 Cartesian expressions. The proof is very easy. 



Cooper's Hill. George M. Minchin. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Oxford. — The following Examiners in Natural Science have 

 been appointed for the Honour -Examinations :— Mr. J. V. 

 Jones and Mr. A. L. Selby (Physics) ; Prof. McLeod and Mr. 

 V. H. Veley (Chemistry) ; Prof. Milnes Marshall and Mr. W. 

 Hatchett Jackson (Morphology) ; Prof. Sanderson and Prof. 

 Schafer (Physiology) ; Prof. Boyd Dawkins and Prof. Green 

 (Geology). 



The conditions of tenure of the Burdett-Coutts Geological 

 Scholarship are to be altered, so as to make it necessary for the 

 holders to devote themselves to Geology, and to work with the 

 Professor. 



Scholarships in Natural Science are announced for competi- 

 tion at Merton and at New College. The examination begins 

 on July 2. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, February 21. — "The Influence of Bile on 

 the Digestion of Starch, (i) Its Influence on Pancreatic Diges- 

 tion in the Pig." By Sidney Martin, M.D., B.Sc, British 

 Medical Association Scholar, and Dawson Williams, M.D. (From 

 the Physiological Laboratory, University College, London.) 



The experiments of the authors have shown that if pig's bile 

 be added to a solution of starch with pancreatic extract the 

 digestion goes on with greater rapidity than without the bile. 

 The rapidity of digestion is increased with the addition of 

 quantities up to 4 per cent, of dried bile (equivalent to at least 1 

 30 per ceht. of fresh bile). The rapidity was tested by noticing | 

 when the iodine reaction of starch had disappeared. On further i 

 research, it was found that this property of the bile depended 1 

 on the bile salts (hyoglycocholate of sodium). The increased 

 Vapidity of digestion was well seen if 06 to 2 per cent, of bile 

 salts were added to the digestive mixtures. ' 



It was also found that not only was the change of starch into 

 dextrine hastened, but also the change into sugar ; and that the 



amount of dextrine and sugar formed when bile-salts wer 

 present was one-fifth more than when they were absent. Fo 

 the methods used in estimating the amount of dextrine and 

 sugar, the original paper must be consulted. 



"The Innervation of the Renal Blood-vessels." By J. Rose 

 Bradford, M.B., D.Sc, George Henry Lewes Student. Com- 

 municated by E. A. Schafer, F.R.S. (From the Physiological 

 Laboratory of University College, London.)- ■ * 



The research was undertaken in order to map out the origin, 

 cause, and nature of the renal nerves in the dog more accurately 

 than had hitherto been attempted. The method employed con- 

 sisted in exciting the roots of the spinal nerves, and observing 

 simultaneously the effects produced on the general blood-pressure 

 and on the volume of the kidney, the latter being investigated 

 by means of Roy's oncometer. The ansestbetics used were 

 chloroform and morphia. The general results were' shortly as 

 follows : — ' : \ 



No efferent vasomotor fibres were found in the posterior loots. 



The efferent vasomotor fibres for the blood-vessels of the kidney 

 leave the cord in the anterior roots of the nerVes, extending 

 from the second dorsal to the second lumbar. The renal nerves 

 are, however, most abundant in the tenth, eleventh, twelfth, and 

 thirteenth dorsal nerves. 



In individual cases, however, there may be small variations in 

 the number of fibres going on the one hand to the kidney, anS 

 on the other hand to the other abdominal viscera. 



When quick rates of excitation are used, only contraction of 

 the kidney and increase of general blood -pressure are observed, 

 i.e. the vaso-constrictor fibres are excited. 



With slow rates, however, expansion of the kidney with na 

 increase of blood-pressure occurs, i.e. the vaso-dilator fibres are 

 stimulated. 



Hence the renal vessels not only receive constrictor fibres, 

 but also dilator, and these are also most abundant in the eleventh, 

 twelfth, and thirteen dorsal nerves. 



Similarly when the peripheral end of the divided splanchnic 

 nerve is excited with slow rates, a fall of blood-pressure is 

 observed instead of the rise seen with quick rates. 



Hence the splanchnic contains not only vaso-constrictor fibres 

 for the abdominal vessels, but also vaso-dilators. 



The results of reflex excitation can be summed up shortly 

 by saying that the excitation of an afferent nerve causing a rise 

 of blood -pressure is accompanied by a renal contraction, unless 

 the nerve is one of what may be called the renal area. In this 

 case the rise of blood-pressure is accompanied, as a rule, by 

 either a renal expansion or else by a mixed kidney effect. 



The main conclusion of this communication is the demonstra- 

 tion of dilator fibres in the splanchnic and in the renal nerves, 

 and also the fact that these vaso-dilator fibres reach the kidney 

 by the same paths as the constrictor fibres. 



Chemical Society, February 7.— Mr. W. Crookes, F.R.S., 

 in the chair. — The following papers were read : — Researches on 

 the constitution of azo- and diazo-derivatives ; compounds of 

 the naphthalene-)8-series (continued), by Prof. R. Meldola,. 

 F. R.S., and Mr. G. T. Morgan. — The action of nitric acid on 

 anthracene, by Mr. A. G. Perkin. Hitherto, only anthraquinone 

 and nitro-anthraquinones have been obtained by treating anthra- 

 cene with nitric acid ; the author, however, finds that nitro- 

 and dinitro-anthracene can readily be prepared by the action of 

 nitric acid upon anthracene if care is taken at once to decompose 

 any nitrous acid which may be formed. — The preparation of 

 glyceric acid, by Dr. Lewkowitsch.— The relation of cobalt to 

 iron as indicated by absorption-spectra, by Dr. W. J. Russell, 

 F.R.S., and Mr. W. J. Orsman, Junr. It is well known that 

 when examined spectroscopically, some coloured metallic com- 

 pounds are found only to produce a general absorption, but from 

 previous observations it seemed possible to the authors that in 

 some cases at least this might be resolved into bands by employ- 

 ing more powerful chemical agents than are generally used in 

 such cases ; experience had indicated that the chloride is usually 

 the most suitable salt, and that it should be dissolved in chlor- 

 hydric acid and the liquid saturated with hydrogen chloride, also 

 that, if possible, ether should be taken as solvent. Applying 

 these views to iron, it was found that ferric chloride gave a 

 banded spectrum strikingly similar to that of cobalt chloride. 

 Irons of all kinds were examined : pig-iron, commercial cast- 

 iron, and various manufactured articles ; steel in the form oi 



