GENERATION OF WARMTH. 41 



time, and the final result is the sum of the work 

 accomplished by the separate pulsations. Fick calls 

 this apparatus a labour-accumulator (^Arbeitsammler). 

 It represents the method by which the whole work of 

 all muscular efforts is summarised. When labourers 

 lift a weight by means of a winch or windlass, a cog- 

 wheel and drag-hook is applied to the axis in such 

 a way that the wheel is free to revolve in one direc- 

 tion but not in the other. This gives cumulative 

 effect to the separate muscular efforts which raise the 

 weight ; and the labourer is even able to make longer 

 or shorter pauses without the result of the work already 

 accomplished being cancelled by the falling back of the 

 weight. 



In tetanus the case is not the same as in separate 

 pulsations. In the former the muscle at first accom- 

 plishes work by raising the weight, and then prevents 

 it from falling by its own exertion. In addition to 

 the height of elevation, it is, therefore, possible to 

 distinguish also the carried height, that is to say, the 

 height at which the weight is permanently supported. 

 In doing this the muscle does not really accomplish 

 any work in the mechanical sense ; for work consists 

 only in the raising of weight. In lifting a stone to the 

 height of the table I accomplish definite work ; the 

 stone being placed on the table presses by its own 

 weight on the latter ; but the table though it prevents 

 the stone from falling, cannot be said in so doing to ac- 

 complish work. So it is in the case of muscle. On raising 

 a weight by means of the muscles of my arm to the 

 height of my shoulder, and then holding out my arm 

 horizontally, the muscles of the arm prevent the weight 

 from falling ; they act just as the table, and, therefore, 



