THE MECHANICAL, THERMAL, AND ELECTRICAL 

 PROPERTIES OF STRIPED MUSCLE. 



By J. Burdon Sanderson. 



Contexts. — The Mechanical Response — Response to Successive Excitations, p. 

 353 — Response to Single Stimulus, p. 358 — Influence of Median ical Conditions 

 on Excitatory Process, p. 363 — Muscular Tonus, p. 377 — Genesis of Tetanus, p. 

 378 — Summation of Stimuli, p. 380 — Period of Latency, p. 381 — Rate of Pro- 

 pagation, p. 383— Conduction of Slow Waves, p. 384 — Exhaustion and Death 

 of Muscle — Fatigue, p. 385 — Causes of Exhaustion, p. 389 — Death of Muscle, 

 p. 390— Rigor Mortis, p. 390 — Nature of Process concerned in Muscular 

 Contraction, p. 393 — Production of Heat durino Contraction, p. 397 — 

 Electrical Properties of Muscle — In the Unexcited State, p. 407 — Current 

 of Injury, p. 411 — Electromotive Phenomena of Excited Muscle, p. 413 — 

 Electrical Response to a Single Stimulus, p. 414 — Electrical Response to a 

 Series of Stimuli, p. 422— Direct Action of Voltaic Current on Muscles — 

 Polarisation of Muscle, p. 426 — Polar Effects during and after Passage of Cur- 

 rent, p. 429 — Polar Excitation, p. 431 — Secondary Excitation, p. 436 — Polarising 

 Action of Currents of Brief Duration, p. 438 — Cardiac Muscle — The Mechanical 

 Response, p. 439 — The Electrical Response, p. 443. 



The function of a muscle is to contribute to the accomplishment of 

 bodily movements, or to the performance of external work, by changing 

 its form in obedience to influences received by it from the central 

 nervous system. 



These influences are comprised under the general term " stimuli." The 

 characteristic of a stimulus is that it evokes the specific function of an 

 excitable organ ; and the characteristic of an excitable organ is that its 

 function is a response to stimulation. Muscle is the type of such an 

 organ. According to the mode of observation employed, the phenomena 

 of muscular function which present themselves to the observer are 

 chemical, mechanical, thermal, or electrical. The present article com- 

 prises the last three of these four classes. 1 



I. — The Mechanical Response. 



In the examination of the mechanical changes which follow excita- 

 tion, we may begin either, with the mechanical effect of a single momen- 

 tary excitation, or by comparing the mechanical properties of a muscle 

 when in a state of excitation with those which it possesses when at rest. 

 For two reasons the latter course is preferable. One reason is that the 

 natural action of a muscle consists in its passing from the unexcited 

 into the excited state, under the influence of a stimulus which acts con- 



1 The chemical changes which accompany the activity of muscle are dealt with in 

 vol. i. The phenomena of muscular contraction which recpiire the aid of the microscope 

 for their observation are described in works on histology, and are therefore omitted here. 



