NA TURE 



[May 4, 1905 



and the author made a rough guess at the proportions of 

 neon and helium in air ; the amount of each gas obtained 

 was known, but the quantity from which they were derived 

 could only be guessed at. The figures were : — of helium 

 one or two parts per million, and of neon one or two parts 

 per 100,000. 



The ingenious method devised by Sir James Dewar 

 of cooling a dense form of charcoal with liquid air, and 

 using it as an absorbent for gases, made it easy to obtain 

 a nearly correct estimate of the amounts of the more 

 volatile constituents, .\fter o.xygen, nitrogen, and argon 

 had been absorbed from about 16,800 c.c. of air by e.x- 

 posure to 100 grams of charcoal cooled with liquid air, 

 the neon and helium were removed with the pump. They 

 were freed from traces of heavier gases by a similar 

 method, and a partial, but fairly complete, separation of 

 the two was effected in the same way. The total quanti- 

 ties were measured by a form of burette, in which the 

 level of the mercury w'as set to a point, and the differences 

 of pressure read. 



The results are : — 



Percentage 

 By "eight By volume 



o 0000S6 ... 0-0000123 



000000056 ... O'O00OO4O 



I vol. in I vol. in 



Neon ... 80,790 ... 757 



Helium.. 245,300 ... 2300 



Together 61,000 ... 571 ... — ... — 



It was not possible to detect the free hydrogen in this 

 quantity of air ; after the crude mi.xture of neon and helium 

 had been mi.xed with a trace of o.xygen and sparked for a 

 few minutes, no contraction was. observed ; the volume of 

 the gases was the same before and after sparking. 



April 6. — " On Reciprocal Innervation of Antagonistic 

 Muscles. — Seventh Note." By Prof. C. S. Sherrington, 

 F.R.S. 



If the crossed extension reflex of the limb be e.\amined 

 before and after a prolonged flexion reflex an alteration 

 is evident in it. When a carefully adjusted electrical 

 stimulus is at regular intervals applied to the afferent 

 path of one limb and the resultant extensor reflex of the 

 crossed limb is noted, it is found that if in one of the 

 intervals a flexion reflex of the latter limb is induced and 

 maintained for twenty seconds or more, the extensor reflex 

 becomes altered in consequence. For a period immediately 

 following the flexion reflex the extension refle.x is in- 

 creased. The intensity of the reflex is heightened, its 

 duration is prolonged, and its latent time is reduced. If 

 the testing stimulus be subliminal the threshold value of 

 the stimulus required by the reflex is found to be lowered. 

 In short, the activity of the flexion arcs directly or in- 

 directly induces in the extension arcs a super-excitability 

 as tested by crossed extension just as when tested by the 

 extensor thrust. 



But although this after-effect of the activity of the 

 flexion arcs upon the antagonistic arcs, both direct and 

 crossed, is one of increase of activity, the primary effect 

 is, as shown previously, one of depression. In these 

 instances there supervenes on the spinal inhibition a re- 

 bound effect of augmentation.' 



The " spinal induction " is obviously qualified to play a 

 part in linking reflexes together in a coordinate sequence 

 of successive combination. If a reflex arc K during its 

 own activity not only temporarily checks the discharge- 

 action of an opposed reflex arc B, but also as a subsequent 

 result induces in arc B a phase of greater excitability and 

 capacity for discharge, it predisposes the spinal organ for 

 a second reflex opposite in character to its own in 

 immediate succession to itself. 



Much of the reflex action of the limb that can be studied 

 in the,*' spinal " dog bears the character of adaptation to 

 locomotion. " Spinal induction " obviously tends to con- 

 nect this " extensor thrust " as an after-effect with pre- 

 current flexion of the limb. In the stepping forward of 

 the limb the flexion that raises the foot and carries it 

 forward clear of the ground, though temporarily checking 

 the reflex discharge of the antagonistic arcs of extension, 

 is, as it continues, so to say, sensitising them to respond 

 later in their turn by the supporting and propulsive ex- 

 tension of the limb necessarv to progression. In reflex 



1 Sherrington, Sch.^fer's "Text-book of Physiology," vol. ii., p. 841, igoo. 

 NO. 1853, VOL. 72] 



sequences an antecedent reflex would thus not only be 

 the means of bringing about an ensuing stimulus for the 

 next reflex,' but in such instances as the above will pre- 

 dispose the arc of the next reflex to react to the stimulus 

 that will arrive. ; 



" Further Experiments and Histological Investigations 

 on Intumescences, with some Observations on Nuclear 

 Division in Pathological Tissues." By Miss Elizabeth Dale. 

 Communicated by Prof. H. Marshall Ward, F.R.S. 



(i) This paper is the third of a series on intumescences, 

 and deals chiefly with two plants, Solanum tuberosum and 

 Populus tremula. On the potato plant intumescences were 

 obtained experiinentally in about twenty-four hours, either 

 on the uninjured plants or on small fragments of leaves. 

 The effect of nutritive solutions on the formation of in- 

 tumescences was investigated. 



(2) Additional anatomical observations were made, anc( 

 a classification of various types of intumescences has been 

 drawn up. The cell contents were examined and compared. 



(3) The occurrence of acids and salts was investigated. 



(4) The experiments show that the internal causes of 

 intumescences are extremely local, and quite independent 

 of root pressure. The osmotically active substance is prob- 

 ably oxalic acid. 



The present experiments show the importance of 

 irritability and active powers of assimilation, as well as of 

 moist air, heat, light, and, generally, oxygen. 



(5) Finally, the nuclear phenomena were investigated and 

 compared, and were found to be in every respect identical 

 in various intumescences and in wound-callus. Patho- 

 logical tissues in certain plants and animals are also 

 compared, and a strong resemblance is seen to exist 

 between certain rapidly formed outgrowths in plants and 

 animals, caused not by any parasitic organism, but simply 

 by the influence of some stimulus, probably always ex- 

 ternal, acting upon a plant or animal in such a condition 

 of irritability that it is able to respond. A similar re- 

 semblance occurs between regenerative wound tissues in 

 certain plants and animals, the formation of which is in 

 all cases accompanied exclusively by the more rapid form 

 of nuclear division known as amitotic or direct. 



Zoological Societv, April 18. — Mr. H. Druce, vice- 

 president, in the chair. — The horn-core (with sheath 

 attached) of an Urus {Bos priinigenius) : J. G. Millais. 

 The specimen was believed to be the only British example 

 of the actual horn of the Urus in existence. The curious 

 corrugations on the surface of the lower end were similar 

 to those found on the American and European bison, and 

 incidentally supported the view that the w'hite cattle of 

 Chillingham, Chartley, and Cadzow were not descended 

 froiTi this animal. — Photograph of the horns of a Roberts's 

 gazelle {Gazella grantii robertsi) obtained by Mr. C. L. 

 Chevalier : O. Thomas. — The discovery of the skeleton of 

 Diplodocus carnegii. Hatcher : Dr. W. J. Holland. Dr. 

 Holland discussed the osteology of Diplodocus, briefly 

 pointing out some of the more interesting structural 

 features of the skeleton, and in this connection anim- 

 adverted upon certain so-called " restorations " made 

 public in popular magazines. Dr. Holland concluded his 

 account by exhibiting in rapid succession pictures of a few 

 of the more remarkable skeletons which had been recovered 

 by the pal^ontological staff of the Carnegie Museum from 

 various localities in the region of the Rocky Mountains. 

 — .\ unique specimen of Cetiosaurus leedsi, a sauropodous 

 dinosaur from the Oxford Clay of Peterborough : Dr. 

 Smith Woodward. The author described the fore and 

 hind limbs and the tail, and confirmed the observation of 

 the late Prof. O. C. Marsh, that Cetiosaurus was one of the 

 more generalised Sauropoda. — On a young female Nigerian 

 giraffe: Dr. P. C. Mitchell. On the evidence afforded, 

 by a young female giraffe, obtained by Captain Phillips in ; 

 the district of Gummel. about 300 miles due west of Lake 

 Chad, and now deposited in the Society's Gardens, thef 

 author was inclined to believe in the distinctness of the! 



1 Loeb's " Ketten-reflexe," discussed in his " Vergleicherde Gehlrn-I 

 physiologie u. Vergleichende P«ychoIoeie," Leipzig, 180Q. p. 96, and j^^. ; 

 compare also Exner, "Entwurf einer physiologischen Erklarung psychis* 

 cher Erscheinungen," Vienna, 1S94, p. 102, and ji-^., under "Successive: 

 Bewegungscombinationen." ) 



