1 66 



NA TURE 



[June 13, 1907 



widespread principle in llie coordination of muscular 

 actions. 



The communication next proceeds to show that the 

 muscles of the limbs are divisible into two groups ; in one 

 group the reflex action provocable excites the muscle itself 

 and relaxes by inhibition its antagonist muscles. To this 

 group belong, among others, the following muscles : — 

 biceps cruris, biceps brachii, gracilis, tensor fasciae femoris, 

 semi-teridinosns, tibialis anticus, and gluteus mininius. In 

 the other group the reflex action provocable from the nerve 

 of the muscle inhibits that muscle itself while exciting 

 reflex contraction in the muscles antagonistic to it. In 

 this group come the following muscles : — vastocrureus, 

 gastrocnemius, soleus, triceps brachii, supraspinatus 

 scapulae and anconeus, adductor magnus, and quadratus 

 femoris. 



The communication finally reverts to the after rebound 

 of contraction which, as pointed out in a previous com- 

 munication on this subject, very usually follows reflex in- 

 hibition of the limb muscles. It is shown that this after- 

 rebound to contraction is of central origin, and can be 

 produced by direct electrical excitation of the cross-section 

 of the spinal cord itself. The rebound contraction is illus- 

 trated by a graphic record of the rebound contraction 

 following reflex inhibition of the gastrocnemius muscle in 

 the cat. 



Geological Society, May 15. — Sir Archibald Geikie, 

 Sec.R.S., president, in the chair. — The origin of certain 

 cafion-like valleys associated with lake-like areas of de- 

 pression : F. W. Harmer. In glaciated regions, as shown 

 by Prof. P. F. Kendall, the invasion of a district by an 

 ice-sheet would tend to obstruct the natural drainage, pro- 

 ducing lakes, of which the outflow might take place over 

 the advancing ice, between the ice and the hillsides, or 

 it might escape laterally, in a direction at right angles 

 to the longest diameter of the lake and to the course of 

 the pre-existing stream. Overflow channels would assume 

 a gorge-like character, and would present a comparatively 

 recent appearance. During the Glacial epoch the North 

 Sea ice appears to have invaded the plain of the Witham 

 and the valleys of the Welland, Nene, and Ouse, over- 

 riding also the higher land separating them ; the Tees ice- 

 slream moved up the Trent basin to the vicinity of Derby, 

 and thence, inosculating with the Derwent glacier, up the 

 Soar valley towards Leicester and Rugby ; the Irish Sea 

 ice passed into the northern part of the basin of the Lower 

 Severn ; ice from the Brecknock Beacons passed towards 

 the Bristol Channel, and, combined with Irish Sea ice 

 crossing Pembrokeshire from St. David's Head towards 

 Cardiff, may have caused the accumulation of sedentary 

 ice in the Severn valley. After considering the case of 

 Lake Pickering and the Malton Gorge as a typical ex- 

 ample, the author passes on to Lake Shrewsbury and the 

 gorge at Ironbridge. Pre-glacial drainage of the upper 

 Severn and Vyrnwy was probably northwards ; when a 

 glacial lake was first formed over the Cheshire plain it 

 may have drained towards the Trent, possibly by Rudyard 

 and Madeley ; when these gaps were closed, the lowest 

 outlet seems to have been towards the south, and the 

 Severn Gorge at Ironbridge was cut. Lake Trowbridge 

 and the gorges of Clifton and Bradford-on-Avon are next 

 dealt with, the latter being attributed to the overflow of 

 a glacial lake occupying the Trowbridge plain, and the 

 former to the blocking of the Flax-Bourton valley by ice. 

 The gaps in the Jurassic escarpment at Lincoln and 

 Ancaster are explained as overflows from a lake caused by 

 the damming of the Trent outlet towards the Humber. 

 This gave rise at first to the more northern, and later 

 to the southern gorge. Finally, Lake Oxford and the 

 Goring Gap are dealt with in considerable detail. 



Royal Microscopical Society, May 15. —Lord Avebury, 

 I'.R.S., president, in the chair. — Diffraction rings due to 

 a circular aperture : Prof. A. W. Porter and P. F. 

 Everitt. The differences between the theoretical and the 

 observed radius of the first dark diffraction ring mentioned 

 in .Mr. Nelson's paper, read March 21, 1906, were con- 

 sidered to be due to the method of observation, because the 

 values obtained from observations made by Mr. Everitt, 

 under the best conditions, were in very close agreement 

 with theory. 



NO. 1963, VOL. 76] 



Zoological Society, May28.— Dr. J. Rose Bradford, F.R.S., 



vice-president, in the chair. — The form of the brain in the 

 extinct lemurs of Madagascar, 'with some remarks on the 

 affinities of the Indrisime : Dr. G. Elliot Smith. This 

 formed a supplement to the paper on recently discovered 

 subfossil Prosimis from Madagascar, read before the 

 society by Mr. H. F. Standing on March lO- From an 

 examination of cranial casts of an extinct species of lemur 

 and of Mesopropithecus and Palajopropithccus, and of 

 brain casts of Nesopithecus and Megaladapis, in conjunc- 

 tion with information derived from the study of recent 

 lemurs, the author had arrived at the conclusion that 

 Propitheeus, Avahis, Indris, Mesopropithecus, Neso- 

 pithecus, PaUeopropithecus, Chiromys, and Megaladapis 

 must be regarded as the diversely specialised members ot 

 one family, all of which exhibited in greater or less degree 

 distinct evidence of retrogressive changes from a more 

 primitive and also more pithecoid type. — Some notes on 

 the abdominal viscera of Chlamydoselachus ; Mrs. O. A. 

 Merntt Hawkes. Observations on the alimentary canal, 

 including the associated glands, the dentition, and the 

 spiral valve of this fish. The results were compared with 

 the accounts of these organs previously given by Garman 

 and Giinther, and attention was directed to any dis- 

 crepancies which had been noted. The female reproductive 

 organs were also examined, and evidence was cited sup- 

 porting the conclusion that Chlamydoselachus was 

 viviparous. The interesting discovery was recorded that a 

 vestigial seventh branchial arch was present. — Second re- 

 port on the batrachians and reptiles collected in South 

 Africa by Mr. C. H. B. Grant : G. A. Bouleneer. The 

 report dealt with fifty-eight species — nineteen Batrachia 

 and thirty-nine Reptilia — of which two were described as 

 new. — Hydroids of the Cape Verde Island marine fauna 

 collected by Mr. Cyril Crossland : J. Ritchie. The collec- 

 tion contained twenty-seven species, and added considerably 

 to our rather meagre knowledge of the hydroid fauna of 

 the northerly portions of the west coast of .Africa. The 

 majority of the specimens hitherto -described from Cape 

 Verde Island had been obtained in comparatively deep 

 water, but the present collection was a littoral one, and 

 contained examples of only one species before recorded 

 from the locality, viz. Sertularia versluysi. Nutting. Of 

 the twenty-seven species represented in the collection 

 eighteen were already known, while the remaining nine 

 were described as new to science. Of the new forms, the 

 most- interesting was a gymnoblast, the peculiar branching 

 and simple gonophore of which separated it so widely 

 from known genera that a new genus had been established 

 for it. 



Cambridge. 

 Philosophical Society, May 6. — Dr. Hobson, president, 

 in the chair. — The influence of a strong magnetic field on 

 the spark-spectra of lead, tin, antimony, bismuth, and 

 gold : J. E. Purvis. The strength of the field was 40,000 

 units. The more important results were : — (i) Comparing 

 the metals separately, there were lines belonging to the 

 same type in having the same number of constituents, the 

 same ratio of intensities of these constituents, the same 

 polarisations, and the same distances apart when re- 

 presented on the same scale of vibration numbers. 

 (2) Comparing the metals with one another, there were 

 lines which were comparable similarly, and this was par- 

 ticularly well marked amongst lines which were divided 

 into four. (3) There were lines of Au, Sb, and Pb yielding 

 four constituents which were essentially identical in every 

 way with lines of the principal series in the spectra of 

 Cu and Ag. (4) The constituents of some of the triplets 

 oV lines in the spectra of the different metals were also 

 comparable with the constituents of some of the quad- 

 ruplets in that the constituents vibrating perpendicular to 

 the lines of force were polarised in the same direction and 

 had the same distances apart when represented on the same 

 scale ■ of d\/\-. — The 13 rays from potassium : N. R. 

 Campbell. An account is given of an investigation into 

 the nature of the rays from potassium which were described 

 in a recent paper by the author and Mr. Wood. The 

 experiments were directed mainly to showing that the rays 

 c.arrv a charge, and must therefore be /3 rays, since their 

 penetration indicates that they cannot be a rays. For 



