248 PHYSIOLOGY OF MUSCLES AND NERVES 



muscle. We may, therefore, conceive the process some- 

 what as follows. The excitement in the nerve, however 

 caused, propagates itself along the nerve-fibre until it 

 reaches the end of the latter. Connected with it is an 

 electric process, by which a sudden electric variation 

 is caused in the terminal apparatus of the nerve- 

 fibre, and this excites the nerve-substance, just as a 

 shock acting externally immediately on the muscle 

 would excite it. 



Following du Bois Keymond, the above conception 

 may be called the discharge-hypothesis {Entladiings- 

 hypothese). According to it, the muscle end of a nerve- 

 fibre must be regarded as similar to an electric plate 

 in the pecuhar organs of electric fish. Indeed, in the 

 latter, an electric discharge is effected by the influence 

 of nerve-excitement, which is able to cause other excit- 

 able structures, such as muscles and glands, to contract. 

 We do not attach any weight to the accidental external 

 resemblance of the terminal nerve-plate to the electric 

 plate. In frogs and many other animals there are no 

 terminal plates, and yet the conditions are the same in 

 their case also. And even if the view upheld by Gerlach 

 is confirmed, and it is shown that nerve-substance comes 

 into more intimate contact with muscle-substance than 

 merely at the point at which it enters the muscle- 

 pouch, our explanation v/ill be unaffected. All that we 

 claim is that an electric discharge, by which the muscle- 

 substance is irritated, takes place in the terminal expan- 

 sions of the nerves, of whatever form these expansions 

 may be. 



Against the acceptance of this view a difficulty at 

 first seems to present itself in the fact that such an 

 electric shock, taking place in the end of a nerve, would 



