814 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



these artificial sections show the same electric conditions with their corre- 

 sponding natural sections. Now, experiments repeated in a great variety of 

 modes demonstrate, that every point in the natural or artificial longitudinal 

 section of a muscle is positive in relation to every part of its transverse section, 

 whether natural or artificial ; and hence a current is passing in the muscle 

 from the transverse to the longitudinal section (Fig. 195). The most 

 powerful influence on the galvanometer is produced, when a portion of the 

 surface (or natural longitudinal section) of a muscle is laid upon one of the 

 electrodes, and a portion of the surface formed by cutting the muscle across 

 (or artificial transverse section) is placed against the other. When the two 

 tendinous extremities of a muscle whose form is symmetrical or nearly so, 

 are placed against the electrodes, the deflection of the needle of the galva- 

 nometer is but slight; and the same is the case with two transverse sections 

 taken at equal distances from the two ends of the muscle, and also with two 

 points of the longitudinal section, which are equally distant from the middle 

 of its length. But if the two points of the longitudinal section applied to 

 the electrodes be not equally distant from the centre of the muscle, then the 

 point which is nearest to the centre is positive to the one which is nearest to 

 the end; and, in like manner, when the different parts of the transverse sec- 

 tion are tested in regard to each other, the points lying nearest the surface 

 of the muscle are found to be positive to those nearest its interior. The 

 intensity of the current, however, between any two points in the same sec- 

 tion whether transverse or longitudinal is always incomparably less than 

 that of the currents which are obtained between two points in different sec- 

 tions, one in the longitudinal and the other in the transverse. These results 

 may be obtained, not merely with the entire Muscle, but with insulated por- 

 tions of it ; and even, as we are assured by M. Du Bois-Reymond, with a 

 single primitive fasciculus. It has been suggested by Hermann that the key 

 to the electrical opposition which exists between the artificial transverse and 

 the artificial longitudinal section is probably to be found in the action of 

 oxygen on the muscular tissue, the surface exposed by the cut being more 

 rapidly acted on, as compared with the longitudinal section, which is pro- 

 tected by more or less fascia, and by the sarcolemma of the fibres. In favor 

 of this view it is to be observed that the more rapidly after removal from 

 the body the electrical relations of the natural longitudinal and artificial 

 transverse sections, or in other words of the tendon and the surface of the 

 muscle, are tested, the slighter is the difference found to exist between them ; 

 indeed, if the examination be made sufficiently early, especially if the animal 

 has been kept in the cold, it will be found either that no difference exists 

 between them, or that the tendon and a portion of the muscle near its longi- 

 tudinal axis are positive in regard to the surface of the muscle. 



665. That a change in the electric state of a Muscle takes place in the 

 act of contraction had been ascertained by the experiments of Professor 

 Matteucci j 1 but as he was only able to detect this by the galvauoscopic frog 

 (the galvanometer which he employed not giving unquestionable indications 

 of it), he was not able to determine its nature with accuracy. This has been 

 accomplished, however, by M. Du Bois-Reymoud ; who has shown that during 

 contraction the muscular current is not increased (as supposed by Matteucci), 

 but is diminished and even reduced to zero. In order to exhibit this phe- 

 nomenon satisfactorily, it is found advantageous to cause the muscle to con- 

 tract powerfully or uninterruptedly for as long a time as possible that is, 

 lo trfiuiize it; and this may be effected by acting violently on its nerve by 

 heat, chemical agents, or a succession of electric shocks; or by poisoning 



1 See his successive Memoirs in Phil. Trans., for 1845, 1847, and 1850. 



