182 ELECTRO-PHYSIOLOGY 



highly favourable action of dilute alcohol to the appearance of 

 break twitch II must surely bear a similar interpretation, 

 although Eckhardt and Kiihne limited its excitatory action to 

 80 / Q . Mommsen, however, has not infrequently observed 

 twitches of the muscle on treating the nerve with comparatively 

 dilute alcoholic saline (20 vol. %), and the same is confirmed 

 by Biedermann's observations. 



The statement that the discharge of break twitch II, as well 

 as the appearance of Eitter's tetanus, is associated with the 

 presence of latent excitation in the nerve, finds striking con- 

 firmation in the fact that break twitch II, with all its character- 

 istic properties as above described, may be elicited in nerves 

 which have been thrown by weak tetanisation into a state of 

 latent excitation (Grlinhagen's process). 



To this end it is only necessary to tetanise the central 

 end of a sciatic nerve, divided from the spinal cord, or still con- 

 nected with it, at a distance of coil which is only just able to 

 excite. If a lower point of the nerve is simultaneously excited 

 with weak descending constant currents, opening twitches will 

 not fail to appear at a moderate duration of closure ; and these 

 twitches are, in every respect, equivalent to break twitch II, 

 since, like the latter, they make a delayed entrance, and are in a 

 marked degree dependent on duration of closure. If current 

 intensity is strengthened, the break twitches become more ex- 

 tended, and finally pass into tetanus, which, like the twitches, is 

 delayed in its entrance. The identity of this opening effect with 

 that described above as secondary is indisputable, seeing that 

 here too the opening of weak currents is followed by a double 

 effect, if the disposition to primary opening twitches is previously 

 induced by brief closure of a stronger current. This effect either 

 consists in double twitches, or else break twitch I appears as 

 introductory to Eitter's tetanus. 



If the nerves are excited during weak and intrinsically in- 

 effective tetanisation by an ascending constant current, there 

 will, in proportion with the intensity of the latter, be either a 

 reinforcement of the closure twitch or closure tetanus, never, how- 

 ever, an opening excitation. 



The application of a fairly strong chemical excitant has 

 substantially the same effect as weak tetanisation above the 

 point of nerve excited by the constant current. Glycerin is 



