PHYSIOLOGICAL EFFECTS OF LABOUR 



207 



FIG. 142./ 



The curve of the fatigue varies very little, as a rule, in the same 

 individual. The shape has been found to be the same for several 

 years, f 1 ) although sometimes it has undergone variations which 



Fio. 143 



rendered it unrecognisable. If a close examination is made of 

 an ergogram, it will be found that its initial portion rises (fig. 143). 

 This ascent is due to the fact that the nervous excitation pro- 

 duces, by its frequency, an internal massage of the muscles, and 

 soon induces more regular functioning (Mosso, Richet), or, in 

 other words, causes a latent addition to the excitations (Richet) . 

 It is known that, by strong electric excitations on the nerve the 

 muscle can be caused to contract without any ascent. 



As to the descending portion of the curve (BC), its decrease 

 is all the more rapid the more defective the mechanical conditions 

 under which the work is done or the physiological state of the 



(*) A. Mosso (Arch. Ital. BioL, vol. xiii., p. 123, 1890) ; A. Maggiora 

 (ibid., p. 187). 



