412 ELECTRO-PHYSIOLOGY CHAP. 



able from the muscle telephone, and had its own characteristic 

 pitch. After poisoning with strychnia also, a deep singing tone 

 was clearly audible in the telephone at the commencement of a 

 spasm. Later on, Wedenski (48) succeeded in hearing the 

 action current of a single gastrocnemius in the frog, with intact 

 circulation, led off by two needles, in the telephone, both with 

 artificial electrical tetanus, and during voluntary contraction, and 

 chemical excitation of the nerve. 



Hesselbach, who worked under Bernstein's directions, pointed 

 out that even a simple twitch from a single induction shock 

 produced an audible sound in the telephone ; which is important 

 with regard to the origin of the first cardiac bruit, and the nature 

 of systolic contraction. To exclude reflexes and voluntary move- 

 ment, the sciatic of the rabbit's thigh was divided ; single in- 

 duction shocks were then led in by two needle electrodes pushed 

 into the gastrocnemius muscle. A momentary dull sound was then 

 quite audible in the stethoscope at every twitch, and also when 

 all change of form and alteration of position in the muscle were 

 excluded by enclosing the ends in plaster of Paris. The " electrical 

 sound" produced by the concomitant variation of current must 

 be distinguished from the "mechanical sound" that is heard 

 directly by the ear in the muscle ; according to Bernstein, how- 

 ever, the two sounds coincide in time. Bernstein concludes that 

 in listening to the bruit, or tone, of the muscle, we do not hear 

 the process of the twitch, or contraction, but that molecular process 

 which is electrically expressed in the action currents ; this, how- 

 ever, postulates that the electrical variation as a whole precedes 

 contraction, which we have seen reason to doubt in the previous 

 discussion. 



We remarked above that every contracted muscle must 

 be regarded as in a state of excitation, while it by no means 

 follows that excitation is always accompanied by corresponding 

 change of form. From this point of view, therefore, it seems 

 not impossible that electrical effects may arise, under certain 

 conditions, without concomitant phenomena of contraction. It 

 has long been known that this is the case where there is a 

 passive block in the muscular contraction, and Fano and Fayod 

 (49) showed that in the auricle even rigid tension did not pre- 

 vent the development of rhythmical action currents, nor are they 

 quelled during the systolic stand-still after poisoning with digi- 



