May 24, 1883] 



NA TURE 



95 



measurements on the optical bench. This was a method (some 

 what similar to that of Mr. Boys, previously described to the 

 Society) for determining the four quantities of a lens on the 

 bench by lineal measures, and without the use of the sphero- 

 meter and prism. Experiments showed that it was about as 

 accurate as the spherometer method. 



Edinburgh 



Royal Society, May 7. — Prof. Maclagan, vice-president, in 

 the chair. — By request of the Council Prof. James Geikie gave 

 an address on recent advances in the Pleistocene geology of 

 Europe. The characteristic deposits of this period, which 

 embraces the Paleolithic age of the antiquarians, were described 

 in considerable detail — the terminal and ground moraines and 

 other glacial remains, the (luviatile and lacustrine formations, 

 and the cave deposits. The limits were indicated of the great 

 Scandinavian ice-sheet, which pushed itself southward over 

 North Germany and over the watershed of Central Russia, and 

 westward across the Ge* man Ocean towards our islands, thereby 

 modifying tbe trend of the native ice-streams that have left their 

 traces all over our hills and round our coasts. As an indication 

 of the great power of this agent it was mentioned that some 

 portions of the brown-coal beds of Saxony which have been 

 long worked are really not in situ, but have been pushed 

 out of place by the ice-sheet. In describing the fluviatile de- 

 posits Prof. Geikie drew attention to a suggestion made by 

 Darwin, that frozen snow accumulating in the valleys below 

 the glacier limits might easily act as barriers and give rise to 

 extensive flooding. The fauna and flora and the evidence of the 

 interglacial beds were then touched upon, and the address ended 

 with a general summary of results with special reference to the 

 climatic peculiarities of the Pleistocene period. It thus ap- 

 peared that Europe was subjected to great climatic changes, 

 severe glacial periods alternating with times of peculiar equable 

 climate in which temperate flora and fauna flourished side by 

 side with forms which are now met with only in southern 

 regions. 



Sydney 



Linnean Society of New South Wales, March 2S. — 

 Rev. J. E. Tenison- Woods, F.L.S., vice-president, in the chair. 

 — The foil iwing papers were read : — Occasional notes on plants 

 indigenous in the immediate neighbourhood of Sydney (No. 3), by 

 Edwin Haviland. This paper refers chiefly to the genus Lobelia, 

 its mode of fertilisation, and its domestication — On tooth- 

 marked bones of extinct marsupials, by Chas. \V. de Vis, B.A., 

 A large proportion of fossil marsupial bones from the Darling 

 Downs, recently examined by Mr. de Vis, are considered by him 

 to show more or less decided traces of the action of the teeth of 

 carnivorous animals. The tooth-marks are ascribed to the agency 

 partly of the native dog, partly of the Thylacoleo, and partly of 

 an extinct species of Sarcophilus which was identified by a por- 

 tion of a tibia. — On Brachalldes palmeri, an extinct marsupial, 

 by Chas. W. de Vis, B.A. A femur from the Darling Downs 

 differs so markedly from that of Macropus and Halmalurus in 

 the less prominent character of the great trochanter that it is 

 considered to belmg to a new generic type, proposed to lie 

 named Brachalldes. — On the habitsof the "Malleehen" {Leipoa 

 ocellata), by K. H. Bennett. This gives an interesting and de- 

 tailed account from the author's own observation of the nidifica- 

 tion and general habits of this very curious bird. — Mr. Macleay 

 exhibited a specimen of Dendrolagus dorianus, a new species of 

 Tree Kangaroo from Mount Owen Stanley, New Guinea, de- 

 scribed by Mr. E. P. Ramsay at the January meeting of the 

 Society. He pointed out that the hair on the body all turned 

 the wrong way. 



Berlin 



Physiological Society, April 13. — Prof, du Bois Reymond 

 spoke about a series of electrophysiological investigations which 

 he began at the same time as his "Investigations in Animal 

 Electricity," which have long since been incorporated in science, 

 now forty years ago, and about which he has as yet not pub- 

 lished anything, viz., about the secondary electromotor pheno- 

 mena of muscles, nerves, and electric organs. These latter are 

 distinguished from primary electromotor phenomena of nerves 

 and muscles by the fact that the latter appear in quiescent 

 organs and take place without being directly influenced by an 

 external electric current, whereas the former appear only as a 

 consequence of an extrinsic electrical current, and consequently 

 are connected with the p ilarisation appearances in electroljtical 

 conductors. When a current is led through a fluid electrolyte 



by means of metallic electrodes, a reverse (negative) p ilarisa- 

 tion current is, as is well known, produced between the 

 electrodes by the accumulation of ions on the anode and 

 cathode. In the year 1836 Peltier described a similar nega- 

 tive (in direction opposed to principal current) polarisation 

 in masses of frogs' limbs through which an electrical current 

 was being passed, and explained it in the same way by the de- 

 velopment of ions on the electrodes. When Prof, du Bois Rey- 

 mond repeated this experiment in the beginning of the forties, 

 he found that an electromotive force was active not only at the 

 electrodes, but that each piece of the preparation through which 

 the current was passing had a negative electromotive reaction, 

 and showed an opposite current fo the polarising one in a gal- 

 vanometer that was applied. On further study of this pheno- 

 menon, he found this "inner" polarisation in every porous 

 conductor, which is soaked with a readily conducting electro- 

 lyte, and it was in all cases negative ; on the other hand an outer 

 positive polarisation exhibited it-elf on the line of cmtict of 

 dissimilar electrolytes, e.g. when the current was led through a 

 pad staked with water into a salt solution. Fresh animil tissues 

 of the most different kinds, when a current was led through 

 them between pads soaked in common salt, accordingly showed 

 an outer positive and an inner negative polarisation. Further, 

 the lecturer studied an outer and an inner secondary (called forth 

 by the current) resistance, of which the former was at least 

 partially accounted for by the cataphorical action of the current. 

 When afterwards (i.e. after the determination of the above-men- 

 tioned physical phenomena) the inner polarisation was studied 

 on living muscles, secondary electromotor appearances of such 

 irregularity and complexity manifested themselves that it was 

 only after laborious investigations that were extended over many 

 years that the simple law that the phenomena obey was dis- 

 covered. It was discovered that when a current was passed 

 through a muscle the inner polarisations might be positive as 

 well as negative, that they depend on the density and length 

 of duration of the polarising current, and that each of these 

 polarisations can be altered in a different manner by these two 

 factors. If the densities and duration of action of the primary 

 current are properly graduated, the phenomena follow the fol- 

 lowing law: — With very weak polarising currents the inner 

 polarisation is negative, and increases up to a certain limit with 

 the duration of the current ; with somewhat stronger currents, 

 the inner polarisation is at first positive, but soon passes over 

 into the negative, which goes on increasing with the duration of 

 the current ; with still stronger currents, the initial positive 

 inner polarisation becomes stronger and longer lasting, and then 

 again becomes negative with the longer duration of the primary 

 current. If the density of the polarising current increases still 

 m ire, the initial positive current becomes weaker and weaker, 

 and finally disappears altogether, and give; way to a polarisation 

 that is negative from the beginning. Accordingly there exists 

 in the interpolar portion of a muscle that is traversed by a 

 current, after a certain limit has been exceeded, a positive inner 

 polarisation, which in a short time is replaced by a negative 

 p ilarisation, and the deduction from these phenomena is that 

 D ith secondary electromotive forces — those with the same and 

 with opposite directions — are present in the portion of muscle 

 traversed by the electrical current. These electromotive forces 

 manifest themselves alternately, the pred iminance of the 

 one and the other being conditioned by the several de- 

 pendence of each upon the density and duration of the 

 primary current. This indication of a positive inner polarisa- 

 tion, i.e. of secondary electromotor forces, which occasion a 

 current in the same direction as the primary current, is a fact of 

 fundamental import in the theory of animal electricity. The 

 positive polarisation proved itself to be dependent upon the 

 direction of the primary current, since it was stronger in the 

 upper half of the muscle when the direction of the current was 

 from below upwards, whereas it was stronger in the lower half 

 with a descending current; furthermore it manifested itself in 

 living muscles only, whereas the negative polarisation occurred 

 also in muscles that had been boiled or otherwise killed ; finally, 

 the positive polarisation was less strong in active than in quies- 

 cent muscles. At the end of the fifties the lecturer had also 

 succeeded in demonstrating a positive inner polarisation in 

 nerves ; it showed the same regularity as was afterwards, with 

 finer appliances, quantitively estimated in muscles ; that is to 

 say, with small current-densities a negative polarisation only was 

 manifested ; with greater current-densities and very short dura- 

 tion of closing a purely positive polarisation was manifested, 



