150 



ELECTRO-PHYSIOLOGY 



CHAP. 



and since this refers to the rapidly-moving M. retractor of the 

 neck, the other muscles of the same animal must yield a still 

 lower value. Bernstein and Steiner (6) found, as we should 

 expect, that the rate of conductivity in warm-blooded muscles 

 (sterno-mastoid of dog) was considerably greater than in cold- 

 blooded animals (3-6 m.), and certain experiments of Hermann 

 (infra} estimate it for living human muscle at between 10 and 

 13m. per sec. 



We are indebted to Rollett (7) for experiments on the rapidity 

 of transmission of contraction in the red and pale muscles of 

 rabbit, which notably present wide differences in regard to the 



FIG. 70. Determination of velocity of muscular excitation by the pince myographiqiie. (Marey.) 



time -relations of their twitches. After freeing the pale semi- 

 membranosus and the red cruralis, he placed a strip 30-40 mm. 

 long between the forceps of a Marey 's pince myographigue (Fig. 70). 

 These were connected with a Marey's registering tympanum, by 

 means of which the curves of expansion were recorded on a rotat- 

 ing cylinder, which also showed a tuning-fork tracing of 100 

 vibrations per sec. A make induction shock served as 

 stimulus. The animals experimented on were curarised. The 

 curve of expansion, corresponding with the excitation point, is 

 again steeper and less extended than the transmitted wave, so 

 that in estimating the time differences between the curves 

 the interval at which they commence is the only datum. The 

 physiological deviations of the pale (quick) and red (sluggish) 



