346 ELECTRO-PHYSIOLOGY CHAP. 



this be true, it is essential to review the known facts of the 

 morphology of motor nerve-endings in vertebrates and inverte- 

 brates in order rightly to appreciate the several theories. With 

 this object we have briefly summarised all the relevant data. 

 Starting with the striking anatomical resemblance (which can be 

 histogenetically accounted for) between the motor " end-plates " 

 of striated skeletal muscle in the higher vertebrates and the 

 nerve-endings in the " electrical plates " of the electric organ 

 of Torpedo (to be described below), W. Krause (55), followed 

 shortly after by Kiihne (56), was the first to express the opinion 

 that the action of nerve upon muscle might depend upon the 

 passing of an electric shock into the latter by means of the end- 

 plates, thereby producing a contraction. From this point of view 

 it must be assumed that the excitation conducted by the nerve 

 to the end-plates induces a brief electrical P.D., as in the electric 

 plates. " One surface of the nerve end-plates, no matter which, 

 becomes positive, the other negative. The resulting electrical 

 shock excites the contractile substance on which it impinges at 

 sufficient density," and a twitch immediately ensues. " Tetanus 

 arises from a more or less compressed series of such shocks." 

 This hypothesis (the so-called "theory of discharge " Entladungs- 

 liypothese of du Bois-Eeymond) gained acceptance, leading inter 

 alia to the conjecture that the secondary twitch from muscle to 

 nerve, discovered by Matteucci, is due less to the production of 

 electricity on the part of the former than to discharges of the 

 intramuscular nerves, or end-plates. Becquerel, without know- 

 ledge of the histological relations, had in fact placed Matteucci's 

 secondary contraction in direct parallel with the physiological 

 shock of the torpedo, referring it to an electric discharge in the 

 muscle (cf. du Bois-Eeymond, 23, p. 15). Klihne's recent 

 investigations have, however, invalidated the suggestion that there 

 may be discharges from the end-plates. For neither does the 

 region by which the nerve enters, which is especially rich 

 in end-organs, exhibit any greater secondary activity than other 

 poorly-innervated or nerve-free tracts of muscle ; nor did Kiihne, 

 in carrying out a method of du Bois-Eeymond, succeed in 

 obtaining secondary twitch from muscles in which excitability 

 had been abolished, with careful preservation of the intramuscular 

 nerves (Kiihne, 2, p. 42). This does not, however, contradict 

 the " theory of discharge," which refers primarily to the relation 



