GENERAL PHYSIOLOGY OF MUSCLE AND NERVE. 125 



This observation indicated that the muscle had a rate of vibration of 18 to 20 

 per second, a rate too slow to be recognized as a tone. He concluded that the 

 tone heard from the voluntarily contracted muscle was the overtone, instead 

 of the true muscle-tone. The consideration that the resonance tone of the 

 ear itself corresponds to 36 to 40 vibrations per second, makes it question- 

 able whether the muscle-sound should be accepted as evidence of the rate of 

 normal physiological excitation ; nervetheless, the experiments with the 

 vibrating reeds remain to indicate 18 to 20 per second to be the normal 

 rate. 



Within the last few years a number of researches bearing upon this question 

 have been published, and the results of these point to a still slower rate of vol- 

 untary excitation, varying from 8 to 12 per second according to the muscle on 

 which the experiment is made. Lov&i 1 discovered in the tetanus excited in 

 frogs poisoned with strychnia, and in voluntary contractions, both by mechani- 

 cal methods and by recording the electrical changes occurring during action 

 with the capillary electrometer, rates of 7 to 9 per second. Horsley and 

 Schafer 2 ex cited the brain cortex and motor tracts in the corona radiata and the 

 spinal cord of mammals by induction shocks, at widely differing rates, and 

 recorded the resulting muscular contractions by tambours placed over the 

 muscles. They observed oscillations in the myograms obtained which had a 

 rate of 8 to 12 per second, the average being 10. The rate of oscillations was 

 quite independent of the rate of excitation, and oscillations of the same rate 

 were seen by voluntary and by reflex contractions. Tunstall 3 found by the use 

 of tambours, in experiments on voluntary contractions of men, a rate of 8 to 13 

 per second, with an average of 10. Griffiths 4 likewise used the tambour 

 method, and studied the effect of tension on the rate of oscillations in voluntarily 

 contracted human muscles. He observed rates varying from 8 to 19, the rate 

 being increased with an increase of weight up to a certain point, and beyond this 

 decreased. The oscillations became more extensive as fatigue developed. Von 

 Kries by a similar method found rates varying with different muscles, but 

 averaging about 10. 



It is not easy to harmonize the view that 8 to 13 excitations per second 

 can cause voluntary tetani, when it is possible for the expert pianist to make 

 as many as 10 or 11 separate movements of the finger in a second. It is, 

 indeed, a common observation that a muscle can be slightly and continuously 

 voluntarily contracted, and, at the same time, be capable of making additional 

 short rapid movements. Von Kries would explain this as due to a peculiar 

 method of innervation, while Biedermann favors Gruetzner's 5 view that the 

 muscle may contain two forms of muscle-substance, one of which is slow to 

 react, resembling red muscle-tissue, and maintains the continuous contraction, 

 the other, of more rapid action, being responsible for the quicker movements. 

 Although the evidence is, on the whole, in favor of the view that all normal 



1 Centralblattfur medidnische Wissenschaft, 1881. 2 Journal of Physiology, 1886, vii. p. 96. 

 3 Journal of Physiology, 1886, vii. p. 114. * Journal of Physiology, 1888, ix. p. 39. 



5 PfliigeSs Archiv, 1887, Bd. 41, S. 277. 



