404: HANDBOOK OF PHYSIOLOGY. 



the body such muscles retain their contractility longer in an atmosphere 

 of oxygen than in an atmosphere of hydrogen or carbonic acid, and dur- 

 ing life, an amount of oxygen is no doubt necessary to the manifestation 

 of energy as well as for the metabolism going on in the resting condi- 

 tion. 



The reaction of living muscle in a resting or inactive condition is 

 neutral or faintly alkaline. 



In muscles which have been removed from the body, it has been 

 found that for some little time electrical currents can be demonstrated 

 passing from point to point on their surface; but as soon as the muscles 

 die or enter into rigor mortis, these currents disappear. 



The Method of Demonstration usually employed is as follows: 

 The frog's muscles are the most convenient for experiment; and a muscle 

 of regular shape, in which the fibres are parallel, is selected. The ends 



FIG. 282. Diagram of Du Bois Raymond's non-polarizable electrodes, a, glass tube filled with 

 a saturated solution of zinc sulphate, in the end, c, of which is china clay drawn out to a point; in 

 the solution a well amalgamated zinc rod is immersed and connected, by means of the wire which 

 passes through A, with the galvanometer. The remainder of the apparatus is simply for conveni- 

 ence of application. The muscle and the end of the second electrode are to the right of the figure. 



are cut off by clean vertical cuts, and the resulting piece of muscle is 

 called a regular muscle prism. The muscle prism is insulated, and a 

 pair of non-polarizable electrodes connected with a very delicate galva- 

 nometer is applied to various points of the prism, and by a deflection of 

 the needle to a greater or less extent in one direction or another, the 

 strength and direction of the currents in the piece of muscle can be esti- 

 mated. It is necessary to use non-polarizable and not metallic electrodes 

 in this experiment, as otherwise there is no certainty that the whole of 

 the current observed is communicated from the muscle itself, and is not 

 derived from the metallic electrodes, in consequence of the action of the 

 saline juices of the tissues upon them. The form of the non-polarizable 

 electrodes is a modification of du Bois Reymond's apparatus (Fig. 282), 

 which consists of a somewhat flattened glass cylinder a, drawn abruptly 

 to a point, and fitted to a socket capable of movement, and attached to 

 a stand A, so that it can be raised or lowered as required. The lower 

 portion of the cylinder is filled with china clay moistened with saline so- 



