October ig, igi i] 



NATURE 



533 



PHYSIOLOGY AT THE BRITISH 

 ASSOCIATION. 

 '"THE presidential address in Physiology has appeared in 

 full in Nature (September 14), and the remainder of 

 the sectional proceedings can be summarised under three 

 heads : reports of committees and papers related to them, 

 discussions, and other communications. 



Reports of Committees. 



Committee on Anaesthetics. — The report contains four 

 appendices. The first describes the installation of a 

 chloroform-balance for daily use in hospital practice. The 

 detailed instructions by Prof. Waller will be extremely 

 useful for anyone who wishes to establish one of Prof. 

 Waller's instruments. The second appendix contains some 

 estimations of the probable percentage of ether inhaled by 

 the " open " method of ether administration. The third 

 appendix relates the experience gained by the use of a 

 chloroform-balance in the out-patient department of St. 

 George's Hospital, and the fourth is a recapitulation of 

 the effect of recent advances on the practice of anaesthesia. 



This report was followed by a paper by Dr. A. Vernon 

 Harcourt, F.R.S., on additions to the use of a chloro- 

 form inhaler. As objection had been made to the vacuum 

 principle of the author's chloroform inhaler, he has adapted 

 his ingenious apparatus to work by the plenum system, and 

 also for use with oxygen. 



Committee on Dissociation of Oxyhaemoglobin at High 

 Altitudes. — The hydrogen ion concentration of blood can 

 be determined by the percentage saturation of haemo- 

 globin with oxygen at low pressures of oxygen. Using 

 this method, it was found that at high altitudes the 

 hydrogen ion concentration of the blood was increased. 



The remainder of the reports contained information of 

 such detailed nature that it is not possible to give a 

 summary of their contents, but in some cases the work has 

 already been published elsewhere. 



Discussions. 



Discussion on Inhibition. — Prof. C. S. Sherrington, 

 F.R.b., opened the discussion by pointing out that it 

 would be of great importance to discover the intimate 

 nature of inhibition. The processes of inhibition are funda- 

 mentally the same whether they occur in the central 

 nervous system or in apparently muscular organs such as 

 the heart. He then described many of the phenomena of 

 inhibition as exhibited by rhythmical reflex movements of 

 the limbs. In dealing with the reciprocal action of 

 muscles, it seems necessary to assume, as suggested by 

 Macdonald, that there is an intercalated neurone in the 

 inhibition path. Any after discharge from the muscle, 

 which ought to have finished contracting, would lead to 

 clumsiness in the alternating movements of flexion and 

 extension ; but inhibition removes all after discharge. In 

 way inhibition diminishes the tonus in muscles 

 antagonistic to those that are contracting. The utility of 

 a common final path is evident, because there cannot be 

 more than one movement going on at the same time ; and 

 so long as a path is held by inhibition contraction cannot 

 occur, and vice versa. Examples were shown of double 

 stimulation and algebraical summation of excitation and 

 inhibition in both flexors and extensors. Two antagonists 

 may be in action together, but their activity increases and 

 decreases in reciprocal proportions ; hence the smoothness 

 and accuracy of trained movements. The conditions 

 favourable to inhibition are fatigue and administration of 

 chloroform, and those favourable to excitation are increase 

 in the " background " stimulation and administration of 

 strychnine and tetano-toxin. According to circumstances, 

 the same stimulus may give either excitation or inhibition. 



Dr. John Tait, rhythmical stimulation of cooled frog's 

 nerve. The Wedensky effect was described, and Frohlich's 

 explanation of the phenomenon was stated. By cooling 

 the nerve a result was obtained similar to that of Weden- 

 skv. The effect is greater the greater the degree of cool- 

 ing, the longer the piece of nerve cooled, and the more 

 rapid the rate of stimulation. Conduction by the nerve 

 is entirely blocked at -2° C, and the phenomenon is 

 present near this point. Fatigue favours the effect. 

 Wedensky effect is shown by well-fed, but not bv under- 

 fed, animals. 



NO. 2igO, VOL. 87] 



Dr. Keith Lucas, conduction between muscle and nerve 

 with special reference to inhibition. Frohlich's explana- 

 tion of the Wedensky effect does not hold in homogeneous 

 tissues, as a second stimulus within the refractory period 

 does not prolong the refractory phase. By indirect stimu- 

 lation it was found that the blocking occurs at the junc- 

 tion between muscle and nerve. The refractory period of 

 nerve is less than that of muscle, and a stimulus 

 sent into the nerve shortly after the end of the refractory 

 period causes a second refractory period. A stimulus to 

 the nerve just after the end of the refractory period is so 

 diminished in strength that it cannot pass the motor end 

 plate. The explanation is that each stimulus to the nerve 

 reduces the response to the succeeding stimulus, and thus 

 all except the first are too weak to pass the resistance of 

 the junction between muscle and nerve ; thus there is a 

 single contraction of the muscle with the first stimulus, and 

 no further response as the stimulation continues. By 

 applying the same processes to the synapses of the central 

 nervous system, an explanation of central inhibition was 

 given. Prof. Waller then spoke, and Prof. Sherrington 

 replied. 



Discussion on ventilation in confined quarters, especially 

 in relation to ships. Dr. Leonard Hill, F.R.S., introduced 

 the subject by explaining that under ordinary conditions 

 the percentage of oxygen is never reduced to a dangerous 

 extent, nor is the carbon dioxide increased beyond reason- 

 able limits. The great factor in ventilation is to provide 

 air under suitable conditions to promote evaporation from 

 the skin and stimulate the nerve endings in the skin. He 

 then described experiments showing that circulation of air 

 in a closed chamber produced the same effect as admitting 

 fresh air in promoting a feeling of well-being. A draught 

 is dangerous, as it causes a local cooling, but cooling of 

 the whole surface by evaporation from the skin is bene- 

 ficial. He described some of the special difficulties met 

 with on board ships, and advocated the wet- and dry-bulb 

 thermometers as a test of the efficiency of ventilation. 

 Fresh air is beneficial, as it dilutes harmful products, such 

 as bacteria. 



An abstract furnished by Prof. N. Zuntz, of Berlin, was 

 read. He agreed with Dr. Hill that oxygen and carbon 

 dioxide are not the predominating factors in ventilation, 

 but he pointed out that there might be poisonous gases 

 given off under some conditions. He then showed that 

 unless the carbon dioxide be kept down to the limit usually 

 given as the maximum allowable, the air becomes almost 

 saturated with the moisture given off from the lungs. 

 Therefore the moisture must be kept down by dilution 

 with fresh air or by condensation on cold surfaces. The 

 use of fans will not entirely remove the need for fresh 

 air, but they will improve the working efficiency of the 

 men. 



Dr. C. J. Martin, F.R.S., spoke in support of Dr. 

 Hill's view by referring to the conditions in Australian 

 gold mines. 



Fleet-Surgeon Whitelegg gave instances of the difficul- 

 ties encountered on board battleships, where, of course, 

 the fighting efficiency was the first consideration. He then 

 described some of the precautions taken before men were 

 allowed to enter unventilated spaces. Dr. Hill then 

 replied. 



Other Communications. 



Prof. H. J. Hamburger, on the influence of iodoform, 

 chloroform, and other substances dissoluble in fats on 

 phagocytosis. In the absence of the author an abstract 

 of this paper was read. In high dilutions the substances 

 used promoted phagocytosis. This effect is the result of 

 the substances dissolving in the lipoids of the cell wall, 

 whereby the surface tension is lowered. When the surface 

 tension is lowered there is less resistance to an increase of 

 surface, and hence amoeboid movements occur more easily. 



Dr. J. Tait and Mr. J. A. Hewitt, certain physical 

 questions regarding blood vessels and blood cells. Blood 

 does not adhere to the endothelium of blood vessels. 

 This is associated with a large amount of ether soluble 

 material in the endothelial cells. Coating glass vessels 

 with oil delays coagulation, as it prevents the adhesion to 

 the glass of certain blood cells. Possibly the high blood- 

 blood-vessel surface tension, as shown by non-adherence of 



