November io, 1923 



NATURE 



709 



Societies and Academies. 



London. 



Royal Society, November i. — E. G. T. Liddell and 

 Sir Charles Sherrington : A comparison between 

 certain features of the spinal flexor reflex and of the 

 decerebrate extensor reflex respectively. Comparison 

 of the tetani of the knee flexor, evolved by motor 

 nerve stimulation and by reflex excitation, shows 

 somewhat close resemblance between them. A 

 constant difference is the presence of after-discharge 

 in the latter. A further difference frequently found 

 is, the myograph records being isometric for both, a 

 -Steeper ascent and sharper ascent-plateau turn for 

 the reflex. The reflex tetanus, like the " motor- 

 nerve " tetanus, appears to engage from its very 

 beginning the full quota of the motoneurones that it 

 will at any time under its further continuance engage. 

 The steeper ascent in the reflex is due to after- 

 discharge setting in early, so that some of the moto- 

 neurones activated by the reflex cannot respond to 

 the immediately succeeding series of stimuli. In- 

 tensity and not duration in the external stimulus 

 is therefore the sole arbiter of the intensity of the 

 reflex tetanus. Similar comparison of the crossed 

 reflex of the knee extensor with the " motor-nerve " 

 tetani of that muscle shows that the reflex tetanus 

 develops much the more slowly, and that the ratio 

 between the tension developed by the reflex contrac- 

 tion to a single shock and that to a serial stimulus is 

 much less than under " motor-nerve " stimulation. 

 The reflex at its outset appears to activate only a 

 small fraction of the quota of motoneurones that it 

 will gradually bring into activity. — J. Barcroft and 

 H. Barcroft : The blood pigment of Arenicola. The 

 blood pigment of Arenicola Marina differs from the 

 Iiaemcglobin of human blood in certain respects. The 

 t band of the oxy - haemoglobin is situated i8 A.U. 

 nearer the violet and the a band of the carbon mon- 

 oxide haimoglobin is situated 1 1 A.U. nearer the violet 

 than the corresponding human band. The dis- 

 sociation curves show a greater affinity for both 

 oxygen and carbon monoxide than tliose of human 

 l>lood. The affinity for carbon monoxide is about 

 70 times that for oxygen, as compared with 250 in 

 man and 140 in the mouse. The possibility of a 

 relationship between the position of the bands and 

 the affinity of the pigment for gas is discussed. The 

 main unloading of oxygen from the pigment of Aren- 

 icola would appear to be between i and 3 mm. 

 jiressure. The mean oxygen capacity of the haemo- 

 ;j;lobin per gram of Arenicola is about o-oi-o-oi3 c.c. 

 A comparison between the oxygen capacity of the 

 ^pigment and the total oxygen consumption of the 

 ^mrm shows that the pigment holds sufficient oxygen 

 supply the animal for 1-2 hours, and probably 

 lets as a reserve to tide it over the period at low- 

 yater when its hole is closed. — T. Deighton : The 

 isal metabolism of a growing pig. Tlie basal meta- 

 >lism of a pig has been measured at various ages 

 rem seventy-five days upwards, and it has been 

 "lown that in the pig, as in human beings, the meta- 

 )lism per unit area is greatest in mid-youth. This 

 icreasc of metabolism in youth .seems to be directly 

 "ascribable to growth. Metabolism after the ingestion 

 of food reaches a maximum after five hours and then 

 declines. The rationing of pigs for maintenance and 

 growth is di.scussed, and it is concluded that the curve 

 of rationing for growth and maintenance, without 

 fattening, cannot |)ossibly be a two-thirds power curve. 



Physical Society, June 22. — Dr. Alexander Russell 

 in the chair. — F. Horton : The excitation and ionisa- 

 lion potentials of gases and v.ipours. The study 



NO. 2819, VOT,. I 12] 



of ionisation potentials dates back to the discovery 

 of the phenomenon of the ionisation of gases by 

 collision, but the theoretical importance of a knowledge 

 of the least difference of potential through which an 

 electron must fall in order to acquire sufficient energy 

 to ionise a gaseous atom or molecule on collision with 

 it has greatly increased since the propounding by 

 Bohr of his theory of atomic structure. Bohr's 

 theory predicted the possibility of an atom being 

 excited to emit radiation by the impact of an electron 

 having energy in excess of a definite minimum 

 amount — an amount corresponding to an " excitation" 

 potential less than that required for ionisation. The 

 experimental methods of investigation may be 

 divided into two classes : (i) Those depending on 

 the detection of the loss of energy by the colliding 

 electron ; (2) those depending on the detection of 

 the radiation or ionisation resulting from the collisions. 



Royal Meteorological Society, October 17. — Dr. 

 C. Chree, president, in the chair. — Sir Napier Shaw 

 and D. Brunt : Towards a basis of meteorological 

 theory : thirty-nine articles of condition for the 

 middle atmosphere. The propositions refer to the 

 " middle layers " of the atmosphere, or those from 

 4 to 8 kilometres above mean sea-level ; that is, the 

 region lying above the effects of the friction of the 

 earth's surface and below the stratosphere. Owing 

 to the normal increase of potential temperature with 

 height, the middle atmospheie is possessed of resilience 

 and may be regarded as made up of separate aero- 

 spheres or horizontal layers which are thermally and 

 therefore dynamically distinct. Air will not pass 

 from one aerosphere to another without some internal 

 source of energy, but there is no resilience for horizontal 

 motion within an aerosphere. That a wide field for 

 discussion is opened is evident from quotation of 

 No. 6 as an example : " The chief effective cause of 

 the general circulation between the equator and the 

 poles and the correlated circulation round the poles 

 is the cooling of the slopes and plateaux of high land 

 in the polar regions." 



Royal Microscopical Society, October 17. — Prof. 

 F. J. Cheshire, president, in the chair. — W. F. Charles : 

 Peculiarities in the development of the ant's foot. 

 On the inside of the lower palate of the snapdragon, 

 and surrounding the base of the stamens, there is a 

 series of glandular hairs containing a viscous fluid ; 

 but these capitate hairs cannot be ruptured by the 

 ordinary claws of the insect. Within the pulvillus 

 of each foot of ants found on snapdragon there appears 

 to be a minute pair "of forcep-Hke claws, developed 

 expressly to enable the insect to grasp and pull itself 

 along hairy surfaces. These claws were sufficiently 

 sharp to puncture certain minute depressions upon 

 the surface of the glandular hairs, releasing the 

 viscous fluid and entangling the ant. The depres- 

 sions on the hairs, which arc covered with one 

 epidermis only, appear to facilitate the rupture. — 

 M. T. Denne : A new variable light screen for use with 

 the microscope. The instrument consists of a 

 cylindrical cell provided with an end plate of glass, 

 and a piston sliding within it bearing a second glass 

 plate arranged so that adjustment with respect to 

 the fixed plate may be effected by a high-pitch screw 

 and nut combined with worm gearing. A coloured 

 or neutral-tinted fluid can be introduced between the 

 plates. With stained preparations, the screen per- 

 mits the gradual intensification of the image of 

 certain elements at the expense of others; with 

 unstained preparations, it gives increjised visibility, 

 while dark ground effects arc distinctly improved. 

 The range given is from total transmission to nearly 

 extinction of the incident beam. 



