202 PHYSIOLOGY OF MUSCLES AND NERVES. 



CHAPTEK XII. 



1. Negative variation of the m uscle- current ; 2. Living muscle is 

 alone electrically active ; 3. Parelectronomy ; 4. Secondary pul- 

 sation and secondary tetanus; 5. Glands and their currents. 



1. The powerful current afforded by an entire m. gas- 

 trocnemius enables us to answer the important question 

 as to the character of electric phenomena during con- 

 traction. All that is necessary is to prepare this muscle, 

 together with its nerve, and to insert its upper and 

 lower ends between the pads of the diverting vessel 

 already described, and then to place the nerve on two 

 wires so that it can be irritated by inductive currents ; 

 it must then become evident whether the activity of 

 the muscle has any influence on its electric action or 

 not. 



In order to carry out the experiment, let us suppose 

 the muscle, as shown in fig. o5, placed between the 

 pads of a diverting vessel, these pads being brought 

 somewhat near each other, so that the contact of the 

 muscle with the pads is not disturbed by the con- 

 traction of the former. The nerve, which has been 

 extracted with the muscle, is laid on two wires which 

 are connected with the secondary spiral of the induct ive 

 apparatus. A key, inserted between the nerve and the 

 spiral, regulates the inductive currents so that the nerve 

 is not excited. When all is arranged, and the multi- 



