i GENEKAL PHYSIOLOGY OF MUSCLE 49 



flexors of the middle finger, on loading with a given weight, and 

 therefore the external work (in kilograrninetres) performed during 

 maximal voluntary effort. The arm is placed in the supine position 

 and fixed to a horizontal support. A leather ring is applied to the 

 middle finger, which carries a string that runs over a pulley and is 

 weighted at the end. Eaising the weight displaces a lever, the 

 point of which records the amount of flexion of the finger. Mosso 

 attached a supporting screw or stop to the indicator of the ergo- 

 graph, by which the flexor muscle of the finger can be relieved of 

 its load during rest, and the weight only pulls on the muscle 

 during its contractions. 



Fio. 30. Two tracings of different types from Mosso's ergograph, taken from two boys of the same 

 age and habit ; in both a weight of 3 kgrms. was lifted every two seconds. 



The most striking results obtained in the earliest researches 

 of Mosso and his collaborators (1890) by the study of the ergograph 

 tracings in a series of voluntary maximal efforts at regular intervals 

 are as follows : 



(a) There is no common type for the ergograph fatigue curve, 

 but each individual has a personal type i.e. under good physio- 

 logical conditions, in a state of repose, with a given load and 

 definite rate, each individual even at long intervals exhibits 

 the same fatigue curve, although the amount of external mechanical 

 work may vary widely (Fig. 30). 



(6) The personal type of the fatigue curve persists even when 

 the fatigue is produced, not by voluntary effort, but by rhythmic 

 electrical stimulation of the nerve or muscle. 



(c) Pronounced mental fatigue or fatigue of all the muscles of 



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