238 



Prof. C. S. Sherrington. Nervous Rhythm [Feb. 3, 



have a frequency of about 8-10* or 7-12 per second.f Figures showing 

 this form have been furnished in previous papers in these ' Proceedings.'* 

 The oscillations are often compounded into or with slower ones so that the 

 graphic records show compound waves. 



In the other form the undulations are slower and often of much more 

 regular rhythm and amplitude than the above. As seen in figures furnished 

 in these ' Proceedings,' by T. Graham Brown, § they show on the muscle 

 contraction as notches or teeth in series from three to seven in number, each 

 undulation lasting not far short of a second. Forbes figures || a remarkable 

 example with oscillations more ample, less regular, proceeding through a long 

 series with a rate often of about 1 per second. 



In a paper of my own an example of this slower form of undulations was 

 figured.1T recorded simultaneously in flexor and extensor muscles of the knee ; 

 it was there (p. 268) pointed out that these undulations are reciprocal in 

 sense in the antagonistic muscles, puffs, so to say, of inhibition in the one 

 muscle's centre corresponding with puffs of excitation in the other's. 

 Graham Brown,** observing the antagonist muscles of the ankle, notes also 

 there that where (fig. 3 of his paper) the undulations were visible in both 

 the antagonists they were reciprocal in them. 



An important suggestion is made by Graham Brown, namely, that these 

 slower undulations are " akin to the rhythmic act of progression."ff This 

 suggestion the results given in the present pages leave no room to doubt 

 is correct. Graham Brown believes " that the rhythmic phenomenon is 

 conditioned by a balance of " " activities which produce in the same centre 

 equal and opposite effects (excitation and inhibition)."^ Forbes,§§ referring 

 to the less regular and less orderly oscillations met in his experiments, 

 writes : " Perhaps all " these oscillations " are manifestations of a general 

 tendency of opposed influences in reflex centres, although themselves con- 

 tinuous, to produce rhythmic activity. If so, it is conceivable that some 

 conditions of intensity or time relations produce the regular movements of 

 progression by enabling the centres to fall into a rhythm natural to them, 



* Forbes, ibid., p. 293. 



f Cf. ' Quart. Journ. Exper. Physiol.,' loc. cit., p. 74, fig. 6. 



\ Forbes, 'Boy. Soc. Proc.,' B, vol. 85, pp. 293, 297, figs. 3, 4; Sherrington, ibid., B, 

 vol. 80, pp. 569-574, figs. 1-4 ; ibid., B, vol. 81, pp. 250, 262, figs. 1, 10. 



§ ' Eoy. Soc. Proc.,' 1912, B, vol. 85, pp. 281-283, figs. 1, 2, 3. 



|| 'Boy. Soc. Proc.,' 1912, B, vol. 85, p. 292, fig. 1. 



If ' Eoy. Soc. Proc.,' 1909, B, vol. 81, p. 261, fig. 9, B. 

 ** ' Eoy. Soc. Proc.,' loc. cit. 

 ■ft Ibid. 

 X\ Ibid., p. 287. 



§§ ' Eoy. Soc. Proc.,' op. cit, p. 297. 



