BIOELECTRIC PHENOMENA S33 



warm-blooded animals the synchronism between innerva- 

 tion and the electromotor response of the muscle con- 

 tinues up to frequencies approaching i,ooo per second.^ 

 Limits are set to the possible rate of electric rhythm 

 by the refractory period of the muscle cells. Recently 

 Gasser and Newcomer, using an amplifying arrangement, 

 have shown that in the normal innervation of the dog's 

 diaphragm, the electromotor rhythm of the phrenic 

 nerve corresponds exactly with that of the muscle; 

 every electromotor wave in the muscle appears to be 

 produced by a corresponding one in the nerve; the 

 rhythms observed varied between 72 and 104 per second.^ 

 It is thus clear that the normal rhythm of excitation in 

 the muscle cells depends on the rhythm of innervation; 

 in the intact organism the latter rhythm is determined 

 by the special rate of rhythmical discharge characteristic 

 of the motor nerve cells ;^ and this rhythm, under the 

 usual precisely regulated physiological conditions, is re- 

 markably regular. 



Experiments of Piper on the influence of temperature 

 on the natural bioelectric rhythm in the tortoise"* have 

 shown that the temperature-coefficient of the rhythm 

 is of the usual order of chemical reaction- velocities. 

 The following frequencies of oscillation per second were 

 observed by him in a string galvanometer connected 

 with the retractor muscle of the neck, which was caused 

 to contract reflexly at different temperatures (see p. 334). 



^ Cf. Hober, Arch. ges. Physiol., CLXXVII (19 19), 305. 



2 Gasser and Newcomer, American Journal of Physiology, LVII 

 (1921), I. 



3 Cf. C. Foa, Z. allg. Physiol., XIII (191 1), 35. 



4 Piper, Arch. Anat. u. Physiol. (Physiol. Abtheil.) (1910), p. 207; 

 also Elektro physiologic menschlicher Muskeln, chap, v, p. 130. 



