June 28, 1883] 



NA TURE 



215- 



elusive. Though different strengths of current were tried, no 

 change in the pupil occurred, unless when the current was so 

 strong as to cause diffuse stimulation. In such cases both pupils 

 would occasionally become dilated, as under sensory stimulation 

 in general. The functional activity of the roots under investiga- 

 tion was shown by contraction of the thoracic muscles on the 

 side of stimulation. 



In the third experiment, however, results were obtained of 

 such definiteness and uniformity as to indicate almost without 

 further confirmation the origin of the dilator nerve of the iris. 



la this experiment the spinal nerves were exposed from the 

 sixth cervical to the eighth dorsal inclusive. The posterior roots 

 were cut on the left side, and the anterior roots stimulated, 

 while the eyes were carefully observed by two assistants — my 

 pupils, Mr. Norvill and Mr. Ea>t. Dilatation of the left pupil 

 o .-curred almost invariably on stimulation of the second dorsal 

 root, whereas no change whatever could be perceived on stimu- 

 lation of any of the other exposed roots. This was verified over 

 and over again, and the several roots repeatedly compared with 

 each other. The distance of the secondary coil in this experi- 

 ment ranged from 20 to iS cm. 



Stronger currents not carefully insulated caused dilatation of 

 both pupils wherever the stimulation was applied, an expression 

 only of general sensory stimulation. 



After death a careful dissection was made for me by Mr. 

 Brooks, and the effective root, which was marked, proved to be 

 the second dorsal. An examination with a lens showed that the 

 fibres of the posterior root of this nerve had been completely 

 severed. 



The results of the third experiment were entirely confirmed by 

 the fourth. 



In this I exposed the spinal nerves from the seventh cervical 

 to the fourth dorsal and cut the posterior roots on the left side. 



Here again with the utmost uniformity on each stimulation of 

 the second dorsal, the left pupil, and this one only, became 

 widely dilated ; whereas stimulation of the other roots was 

 entirely negative in respect to the pupil. 



I ascertained in this experiment that a strength of current 

 which would suffice to excite the muscles of the limb or trunk 

 to action would frequently fail to cause any dilatation of the 

 pupil when applied to the second dorsal. Somewhat stronger, but 

 yet barely perceptible on the tongue, the current at once caused 

 the pupil to dilate. Occasionally alo if the second root had 

 been stimulated repeatedly the ins failed t > respond, probably 

 from mere exhaustion of the nerve. 



Circum-tances such as these would, I think, account for the 

 absence of the pupil-reaction in my first experiment, and also in 

 the experiment related by Prof. Yeo and myself, where the 

 second dorsal root was really under stimulation. 



The general result of these experiments is to show that in the 

 monkey, and presumably also in man, the dilator fibres of the 

 iris contained in the cervical sympathetic are derived from the 

 anterior root of the second dorsal nerve. 



Mathematical Society, June"l4. — Prof. Henrici, F.R.S., 

 president, in the chair. — Prof. W. Woolsey Johnson, of Anna- 

 polis, was admitted into the Society. — Prof. Cayley, F.R.S., 

 spoke on the subject of sever invariants, and Mr. Hammond's 

 recent discovery. — Prof. Sylvester, F.R.S. (who was very 

 cordially welcomed), and Mr. Hammond spoke on the same sub- 

 ject. — Mr. Tucker (Hon. Sec.) read parts of papersby Prof. 

 H. Lamb, on the mutual potential of two lines in space ; by 

 Mr. II. M. Jeffery, F.R.S. , on bicircular quartics with collinear 

 foci ; and made a few remarks on the subject of inverse coordi- 

 nate curves. 



Physical Society, June 9. — Prof. Clifton in the chair. — 

 Dr. Obach described an improved construction of the movable 

 coil of galvanometer for determining currents and E.M.F. in 

 absolute measure. This is a more sensitive, accurate, and 

 powerful instrument than the old form. It is intended for accurate 

 measurements and testing other instruments. The needle of the 

 new form does not dip ; and its vibrations are rendered dead 

 beat by an air chamber. The secants of the inclination of the 

 coil are the multipliers of the tangents of the deflections. The 

 coil consists of a single solid rod or band of copper for measuring 

 powerful currents ; and on the same ring is a fine coil of German 

 silver wire for measuring E.M.F. No shuit is required, owing 

 to the movability of the coil. Dr. Obach gave figures showing 

 the accuracy of the apparatus, which is very great. — Professors 

 Ayrton and Perry read a paper on the electric resistance of water, 

 being the result of some experiments made by them some time ago. 



A comparison of the galvanometer and elec'rom-ter methods of 

 measuring this resistance was made during the experiments, the 

 results being in favour of the latter, especially with currents of 

 less than 6 volts. When the electrodes or platinum plates in 

 the water were end-on, the resistance was less than when face to 

 f^.ce. Mr. Boys thought this "curious result might be due to the 

 resistance between the surface of the plates and the water being 

 reduced. In answer to Dr. Coffin, Prof. Ayrton stated that the 

 plates were heated between every two experiments in the blow- 

 pipe. Prof. G. Guthrie lemarked that Kohlrausch had found 

 ordinary distilled water to be much more conductive than pure 

 dUtilled water, which was an insulator, and inquired if Prof. 

 Ayrton chose pure water. The latter replied that as his 

 experiments were to test the merits of the galvanometer and 

 electrometer modes of testing, ordinary distilled water wa. 

 used. Prof. Jones stated that he found it best to use alter- 

 nating currents for measuring the liquid resi tance of cells, 

 and described a mercury commutator for rapidly reversing the 

 testing current. — Prof. Ayrton then described a lecture appa- 

 ratus for showing the laws of centrifugal force. A rapidly 

 rotated arm carrying a movable weight springs from the centre 

 of an aneroid chamber filled with mercury. This chamber is on 

 the rotating axle, and as the centrifugal force of the arm pulls 

 out the diaphragm, the mercury falls in the chamber and in a 

 tube opening from it. Prof. Guthrie remarked that the appa- 

 ratus would serve as a speed counter. — Prof. Perry then read a 

 paper on the kinetic energy of rotating bodies, in which he 

 pointed out the practical drawbacks to the "moment of inertia " 

 calculations, and suggested the use of a new constant (termed foi 

 the nonce the " M "). This is.the amount of kinetic energy pos- 

 sessed by a rotating body when making ore revolution pei 

 minute. To find the energy for N revolutions per minute, 

 multiply this by N-. In the same way the "M" of a machine 

 can be found and used. 



Paris 



Academy of Sciences, June n. — M. E. Blanchard, presi- 

 dent, in the chair. — On some properties of a binary form of the 

 eighth order, by F. Brioschi. — On the homogeneity of mathe- 

 matical formulas, by A. I.edieu. — Four methods of separating 

 gallium from iridium, by M. Lecoq de Boisbaudran. — Process 

 to be adopted in observing the first radicules of the lympha'ic 

 system, and in determining whether these radicules communicate 

 or not with the blood capillaries, by E. Sappey. The intimate 

 union of the radicules with the bloodvessels, which had long 

 been assumed on general grounds, is here demonstrated by actual 

 observation. — Researches on rabies, by Paul Gibier. The points 

 examined are (1) the manner of inoculation ; (2) transmission of 

 rabies through the mother ; (3) the presence of foreign sub- 

 stances in the stomach of the dog in connection with the dia- 

 gnosis of rabies ; (4) attenuation of the virus : (5) the parasites 

 of rabies. The author shows that the canine, like some other 

 kinds of virus, may be attenuated by cold. That hydrophobia 

 is due to a special parasite, although not yet scientifically demon- 

 strated, is rendered highly probable. — Facts and results serving 

 to determine some new properties of sulphate of iron, by 

 M. Rohart. — On the properties of phosphoric glass (the so- 

 called verre de phosphate de chaux), by M. Sidot. — M. 

 de Quatrefages presented, on behalf of M. de Lacerda, 

 a memoir on an organism found in the victims of yellow 

 fever, and by him regarded as a fungus. In the accompany- 

 ing plate are represented the various stages of development 

 of this organism. — On the track of Encke's comet in the years 

 1871-1881, by M. Backhand. — On a mode of transformation of 

 figures in space, by MM. J. S. and M. N. Vanecek. — On the 

 theory of the binary form of the sixth order, by R. Perrin. — A 

 study of continuous periodical fractions, by E. de Jonquieres 

 (continued). — On the reflection of light on the surface of dis- 

 turbed fluids, by L. Lecornu. — On the variation of the capillary 

 constant of insulating liquid surfaces, such as ether and sulphuret 

 of carbon, in contact with water, under .he action of an electro- 

 motive force, by M. Krouchkoll. — On the formation of the 

 glycolate of biba-ic soda, by M. de Forcrand. — On the hydrates 

 of barytes, by E. J. Maumene. It is shown that barytes makes 

 no exception to the general law of hydrates, with which the 

 numerous results obtained by Fremy, Fllhol, Deville, and others, 

 are in harmony. — On the fermentation of bread-stuffs, by V. 

 Marcano. — On the artificial production ofbarytine, ccelestine, and 

 anhydrite, by A. Gorgeu. — On the origin and process of forma- 

 tion of bauxite and granular iron, by Stan. Meunier. — On respira- 

 tion in rarefied air, by MM. Fraenkel and Geppert. 



