ir CHANGE OF FORM IN MUSCLE DURING ACTIVITY 137 



and one of 933 vibrations is faintly audible. At a frequency of 

 1056 stimuli, however, only a tone a 'fifth or an octave lower was 

 perceptible. Loven (34) places the limit of reaction in rabbit 

 muscle much lower. When all due precautions were taken, he 

 heard from M. tibialis anticus, on exciting its nerve with very 

 weak induction currents at a frequency of 330380 per sec., a 

 tone which was nearly always a distinct octave below the tone of 

 the interrupter ; it disappeared on intensifying the strength of 

 current, and reappeared finally at a certain intensity in unison 

 with the exciting tone. In individual cases the two octaves 

 appeared with medium stimulation, sometimes simultaneously, 

 sometimes alternating with one another. But a true muscle-tone 

 was never emitted at a higher frequency than 880 per sec., 

 corresponding to a", which the muscle responded by a', the lower 

 octave. With higher frequency of stimulation a dull, muscular 

 bruit only is heard, and no tone corresponding to it. Experiments 

 in which the sciatic nerve was tetanised by the telephone gave 

 similar results. With progressive alterations of pitch by singing 

 into it the scale from g (198 vibrations) to y' (396 vibrations), 

 Loven clearly heard the whole scale given out by the muscle up 

 to c f (264 vibrations); the d f was very indistinct, e f )t fis', and g, 

 on the other hand, again produced clear, muscular tones, but they 

 belonged to the lower octave. Kronecker and Stirling (14) had 

 found that on stimulating the pale gastrocnemius of rabbit with a 

 Konig's tuning-fork (180 vibrations), introduced into the induction 

 apparatus, or with the rapidly- vibrating Wagner's hammer, the 

 tone corresponding to the number of vibrations in the interrupter 

 was heard with every characteristic of its pitch, " as if the con- 

 ducting wires were sound conductors." But this experiment is 

 not confirmed by Loven. In every case, even on singing into the 

 telephone, "the muscle -tone was conspicuously dull and low- 

 pitched," only the ground-tone of its deeper octave being given 

 out, never the over-tones. Wedenski's observations (35), which 

 refer specially to the detection of the action currents of tetanised 

 muscle by the telephone (infra], also indicate that the capacity of 

 striated muscle to respond to very frequent stimuli by correspond- 

 ing, rhythmical alterations of state, is limited. Previous to the 

 upper limit of rhythmical stimulation-frequency, at which the muscle 

 only replies by a dull, unmusical sound, an exception occurs to the 

 rule that holds at the beginning i.e. that pitch corresponds with 



