GENERAL PHYSIOLOGY OF MUSCLE 55 



the ergogram, and forms an essential part of it. This proves that 

 supporting of the ergograph lever creates artificial work conditions, 

 which, together with the variations in elasticity and tone which 

 the muscle suffers during work, cause a more or less rapid 

 decline in the successive contractions, and shorten the ergogram 

 prematurely. 



In extending his investigation to voluntary work, Treves found 

 it necessary to alter his system of loading, and to apply the 

 principle of maximal loading in this case also that is of gradually 

 altering the weight as the muscular power declines. In this study 

 he employed the flexor muscles of the forearm, and invented a 

 new ergograph for the purpose which may be studied in his 

 original memoir. 



A minute analysis of Treves' results is beyond the scope of 

 this text-book. We must confine ourselves to a few of the most 

 important principles that can be deduced from them : 



(a) During voluntary work on the ergograph the height of 

 contraction remains constant so long as the conditions of work are 

 favourable, and above all so long as the load is not excessive. 



(6) The maximal load that can be raised by voluntary effort 

 corresponds with the load which necessitates the maximum of work. 



(c) The maximum load diminishes gradually in a hyperbolic 

 curve till it reaches a value which varies with the rate of work, but 

 is practically constant. The curve of voluntary work, like that 

 obtained by artificial stimulation, consists of two phases a 

 descending and a constant part. The differences seen in the two 

 curves arise from the fact that in the case of work elicited by 

 artificial stimuli the stimulus is constant ; in voluntary work, on 

 the contrary, the effort varies since it diminishes independently of 

 the will, according to the resistance experienced in carrying out 

 the movement. 



(d} The ergograph tracing consists of a series of vertical lines 

 approximately equal in height, with no feature characteristic of 

 the individual or of the experimental conditions. The true 

 ergogram is the line according to which the work diminishes with 

 the maximal load. 



(e) The main factor which determines the rapid fall of the 

 curve with a constant load is the appearance of unfavourable 

 mechanical conditions. To obviate this the muscles must be left 

 perfectly free to contract, and the contraction of other muscles 

 connected with those under investigation must not be hindered. 

 It suffices to see that the graphic apparatus records only the 

 movements of the bony lever in question. Further, the normal 

 conditions under which the muscle acts must be respected, and 

 the gradual unloading of the muscle during contraction permitted, 

 as would happen by the displacement of the bony lever on which 

 the muscle naturally works. 



