ADVANCED EXPERIMENTAL PHYSIOLOGY 



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ducing equal stimulation of every fibre, leads to an apparent recovery 

 of voluntary power. In this way is to be explained the apparent 

 paradox, that a muscle fatigued by either voluntary or peripheral 

 stimulation shows a recovery of power when stimulated in the opposite 

 way. 



In order to investigate this subject we shall compare the curve of 

 voluntary fatigue taken with a spring ergograph from the human 

 abductor indicis, with the curve obtained from the frog's gastrocnemius, 

 with its circulation intact and stimulated through the sciatic nerve. 



The Spring Ergograph. A simple form of this instrument is shown 

 in Fig. 182 to consist of a rigid upright iron bar which is clamped to 



Fio. 182. Spring ergograph. (Porter.) 



the table. From the upper end of this projects a horizontal straight 

 steel spring, the free end of which carries an ordinary writing point. 

 The spring carries on its under side a short vertical steel arm, the lower 

 end of which fits over the distal end of the second phalanx of the index 

 finger. When the abductor indicis contracts the spring is pushed up ; 

 by sliding the vertical arm along the spring the magnification of the 

 movement and the strength of the spring can be altered. The hand is 

 placed along the vertical side of the wooden support and the three 

 outer fingers tied to it, leaving the thumb and index finger free. The 

 forearm should be fixed to the bench in some form of support, but care 

 must be taken not to tie down the arm sufficiently tightly to interfere 

 with its circulation. 



The subject of the experiment should sit comfortably and with his 

 eyes shut, should not be spoken to nor in any way have his attention 

 diverted, but should confine himself to giving a maximal contraction of 

 his muscb every time he hears the beat of a metronome, which 

 is set to give a beat every second. The observer takes the time 

 of the experiment in minutes and so calculates the number of contrac- 

 tions recorded, further he has to see that the vertical arm does not slip 



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