424 ELECTRO-PHYSIOLOGY CHAP. 



rhythmical secondary contraction by the heart -beat. A simple 

 method of obtaining a whole series of secondary twitches from 

 ordinary skeletal muscle, reflexly excited, is that given by Kiihne 

 (I.e. p. 63): a lizard's tail, amputated and curled up, produces 

 vigorous excitation in the nerve of a frog's leg brought into 

 contact with it. Natural rapid contractions do accordingly 

 possess considerable secondary efficiency. 



The telephone, as a proof of the discontinuous electrical 

 wave of variation in muscle in natural tetanus, presents great 

 advantages over the rheoscopic test. Bernstein and Schoenlein 

 (56) heard "a deep, singing tone of unmistakable clearness" on 

 the strychninised rabbit at the outset of spasm. Later on 

 Wedenski (48) organised a whole series of experiments in this 

 connection. At each energetic natural contraction of triceps 

 femoris in the frog, he succeeded in hearing a perfectly distinct 

 murmur (aspiration) in the telephone. The same effects, only 

 more intense and persistent, were heard during spasms produced 

 by destruction of the spinal cord. Wedenski also experimented 

 on himself (by pushing two needles into his biceps brachii), as 

 well as on toads, dogs, and rabbits. The animals were either 

 poisoned with strychnia, or tetanised from the cord. In all these 

 experiments a hardly definable, but deep and regular murmur or 

 aspiration, was heard, like the sound of a distant waterfall. If 

 the arm is held out for a considerable time, the murmur becomes 

 weaker, and eventually dies out (fatigue). The sound is deep, 

 but its pitch indeterminable ; the attempt to determine it 

 synthetically by artificial measures gave negative results, since 

 excitations of 8-20 beats per sec. yielded electrical tones of 

 a perfectly different character from the murmur heard in the 

 telephone in voluntary contraction. 



However completely the telephone may attest the oscillatory 

 nature of the electrical processes in voluntary, active muscle, it 

 has the great defect of giving no determination of frequency of 

 variation. 



The cause of the failure of secondary tetanus in the above- cited 

 instances has been the object of repeated investigation. Du Bois- 

 Reymond (1) pointed out the relative instability of voluntary and 

 strychnia tetanus. Supposing the contractions of the different 

 groups of fibres in a muscle not to occur simultaneously, it is 

 conceivable that the electrical variations, led off externally, might 



