514 APPENDIX 



motor nerves and those of the viscera, as is seen clinically oftentimes in 

 congestions from exposure to external cold. 



In this experiment as carried out here all vaso-motor control of the 

 viscera is destroyed and the main bulk of the blood collects where the 

 force of gravitation draws it. 



Expt. 83. Neuraxones Practically Unfatiguable. (Apparatus: 

 Moist-chamber, inductorium, two dry-cells, platinum electrodes, myo- 

 graph, keys.) Arrange the gastrocnemius nerve-muscle preparation in 

 the moist-chamber in connection with the muscle-lever below and place 

 the end of the long nerve on the platinum electrode connected with the 

 secondary coil of the inductorium arranged through a key for tetanizing 

 currents. On the nerve between this stimulating electrode and the 

 muscle place two fine wire non-polarizable electrodes so that there will 

 be a descending current connected with the other dry-cell through a key. 

 Observe that the muscle contracts when stimulated with the induction- 

 shocks. Throw through the nerve the galvanic constant current, and 

 while it is passing stimulate again. No contraction now occurs, for the 

 constant current acts as a " block" to the transmission of the stimulus 

 by lowering the irritability of the neuraxones. Now leaving the galvanic 

 current running, stimulate the nerve continuously for a long time with 

 the rapidly tiring tetanizing current. Such stimulation would fatigue 

 the "muscle" quickly, but the galvanic block prevents this, although not 

 preventing active stimulation of the nerve between the platinum electrodes 

 and the " block." After long stimulation shut off the galvanic current, 

 thus removing the block, and short-circuit the induction current. Now 

 open the short-circuiting key, thus again stimulating the muscle through 

 the nerve. The muscle contracts quite as well as if the nerve had been 

 unstimulated. 



It cannot be surely said that neuraxones are theoretically, that is 

 absolutely, unfatiguable, for it is inconceivable that a form of protoplasm 

 so delicate and elaborate chemically as is nerve should not suffer from 

 exhaustion of its stored energy, whatever it is, when continuously drawn 

 upon for very long periods. There is a normal balance between ana- 

 bolism and katabolism which must be disturbable after a time. The 

 functioning of nerve may be, however, sufficiently intermittent to allow 

 of apparently continuous performance, just as the heart seemingly works 

 continuously. In reality, as we know, it rests three-quarters of the time, 

 and only for this reason needs no long periods of rest. 



Nerve-cells are fatigued with comparative ease, as was shown by Hodge. 

 He kept sparrows flying continuously for many hours, and then compared 

 their cortical motor cells with those of sparrows which had been at rest. 

 The changes both in the cytoplasm and the nuclei were very striking, both 

 being much shrunken. (See Fig. 27.) 



Expt. 84. The Influence of Strychnine. (Apparatus: Pipet, 0.5 per 

 cent, solution of strychnine, seeker.) Pith the brain only of a frog. Into 

 one of the lymph-sinuses lying on either side of the spinal column inject 

 a single drop of the strychnine-solution with the pipet. In a few minutes 



