108 GENERAL PROPERTIES OF LIVING TISSUES 



contraction on closure. Watch very closely the 

 cathodal region near the junction of the muscle 

 fibres with the tendon. Close the key. 



After the closing contraction, the ends of the 

 muscle fibres next the tendon in the cathodal 

 region will show a faint but distinct thickening, 

 which will remain until the current is broken. 



These several experiments demonstrate that in 

 galvanic stimulation of both skeletal and smooth 

 muscle the excitation takes place at the points 

 where the current leaves and enters the muscle. 

 Before inquiring whether this law holds good for 

 the heart, the muscle cells in which have a form 

 intermediate between the smooth muscle cell and 

 the cells of skeletal muscle, it will be necessary 

 to consider whether the points of contact with 

 the electrodes are always the real anode and 

 cathode. 



Physiological Anode and Cathode, When the 

 electrodes are placed directly on a nerve, or are 

 applied to a muscle with straight parallel fibres in 

 such a way that the current flows through each 

 fibre from end to end, the anode and cathode 

 obviously coincide with the points at which the 

 electrodes touch the muscle. When, however, 

 the fibres are of irregular shape, or are irregularly 

 disposed, the current lines can no longer traverse 

 the fibres from end to end, but will enter and 



