iv ELECTROMOTIVE ACTION IN MUSCLE 429 



has succeeded, though rarely, in producing secondary excitation 

 from muscle to muscle by means of electrical conductors (salt 

 clay), an experiment from which du Bois-Eeymoud obtained the 

 first indisputable proof that Matteucci's twitch depended on 

 electrical processes in the primary muscle. As regards the 

 cause of the remarkable effect produced by compression of the 

 muscle on its secondary activity, some light is obtained from ex- 

 periments recently carried out re effect of dehydration from 

 desiccation (Biedermaun, 58). 



If dead, skinned frogs, or even parts of such, are exposed freely 

 in the air for some hours, at not excessive external temperature, 

 they take on very remarkable properties at a certain stage of 

 desiccation, which distinguish them in a marked degree from 

 normal muscles, even at a high state of excitability. Here, as 

 in partially compressed muscles, every stimulus, however localised, 

 produces an .extremely vigorous and also protracted, persistent 

 shortening of the whole muscle directly affected, and in many 

 cases of other accessory muscles also, so that energetic movements 

 and changes of position result in these extremities, often producing 

 an impression of reflex or voluntary movements. The excitability 

 is not seldom heightened to such a degree that even the least 

 shake, such as lifting the dish containing the skinless remains of 

 the frog, suffices to throw certain muscles into persistent contrac- 

 ture ; a gentle touch of the dry surface always produces this 

 result. It is easy to demonstrate that this reaction in dried 

 muscle is principally due to dehydration of the superficial layers 

 of fibres, by moistening every point found to be sensitive 

 to mechanical or electrical stimulation with physiological salt 

 solution, on which the characteristic effect soon disappears 

 permanently, although it may still be elicited in other dry 

 parts. 



If an isolated sartorius at the right stage of desiccation 

 is placed upon a glass dish with the non-fasciculated inner side 

 turned downwards, a series of effects can be produced by the 

 most simple methods, which mark off such a preparation distinctly 

 from the normal muscle, however excitable. Excitation, with a 

 needle, of the fibres adjacent to the inner or outer margin, at any 

 point, results, as a rule, in vigorous contraction of the whole 

 muscle, so that there is no doubt that the excitation which was 

 originally limited to a few primitive fibres communicates itself in 



