194 PHYSIOLOGY OP MUSCLES AND NERVES. 



the direction from the positive to the negative point ; 

 but that, if the feet are both positive, or both negative, 

 the current passes from the more to the less positive 

 point, or from the less to the more negative point. 

 From the curves in A and 5, fig. 51, which show the 

 tensions, the currents indicated in fig. 50 may therefore 

 easily be discovered. 



3. Once more let us take a muscle, the fibres of 

 which are parallel, and cut a piece out of this, but in 

 such a way that the cross-section, instead of being at 

 right angles to the direction of the fibres, is obliquely 

 directed toward the latter. A piece of this sort may be 

 called a onuscle-rhomhus ; if the cross-sections are 

 parallel to each other, it is a regular muscle-rJiombus ; 

 if otherwise, an irregidar niiiscle-rlioinhus. In such a 

 muscle-rhombus, the distribution of the tensions, and, 

 consequently, the form of the iso-electric curves, is 

 much more complex than in a muscle-prism. In this 

 case the cm'ves are not, as in a muscle-prism, parallel, 

 but are sometimes of very complex form. 



It is true that in this case also there is the main 

 distinction between the lonsfitudinal section, or outer 

 surface of the muscle-rhombus, and the cross-sections. 

 The former are always positive, the latter negative. 

 But both in the lonijitudinal and cross-sections a 

 difference is noticeable between the obtuse and the 

 acute angles. The positive tension is greater at the 

 obtuse than at the acute angles of the longitudinal 

 section ; and, similarly, the negative tension is greater 

 at the acute than at the obtuse angles of the cross- 

 sections. Consequently, a peculiar displacement of the 

 tension-curves, of which fig. 52 is intended as a re- 

 presentation, takes place in a regular muscle-rhombus. 



