GENERAL PHYSIOLOGY OF MUSCLE 



53 



this they showed no tendency to further diminution (Fig. 31). 

 On the usual interpretation of ergograph curves it would be said 

 that the muscle had become incapable of any further work at this 

 point. But this is not the case ; the muscle is still capable of 

 serving up a considerable amount of external work. For if the 

 weight is gradually reduced, the height of the contraction again 

 increases until a new maximal weight is found which yields 



Fn:. 33. Ergograph tracing of rabbit's gastrocnemius, after ten minutes' rest, during phase 



of constant work. (Treves.) 



the maximum of work (Fig. 32) and corresponds to about 

 400 grms., i.e. much less than the original weight, which was 

 1150 grms. If the rhythmical maximum excitation is continued 

 with this new load (which may be called the terminal maximal 

 load), an endless series of contractions is obtained, which correspond 

 with the production of constant work. The series of contractions 

 following on a falling curve exhibits similar constancy, irrespective 

 of the load which is carried. Fig. 32 reproduces a few cm. only 

 of the tracings obtained with different loads in testing for the 



Fin. 34. Ergogram of rabbit's gastrocnemius, loaded with 600 grms., after twenty minutes' rest, 

 during phase of constant work. (Treves.) Before resting the muscle gave at each lift a 

 constant yield of 400 grms. x 4 mm. = 1600 grm. mm. After resting the maximal work was 

 600 grms. x 11 mm. =6600 grm. mrn. 



terminal maximal load in the second phase of the ergogram. 

 This constant phase may preserve its regularity at a rhythm of 

 1 sec. for over 2000 consecutive contractions, each representing 

 work that may amount to 2500 gr. mm. 



If the muscle is allowed a longer or shorter pause for rest 

 during the period of constant work, the maximal work of which it 

 is capable at each contraction increases again, in proportion as the 

 resting-pause has been longer. This partial recovery of power is 

 shown in the capacity of the muscle to trace a new ergogram with 



