OF VITAL MOTION. 103 



of contraction, and proceeded to notice the effects of 

 an additional weight. He proceeded as before, and 

 found a similar train of results. There were, indeed, 

 no signs of action so long as the pin remained ; but 

 on removing this, the beam once more ascended, and 

 the muscle began to contract, after a certain degree 

 of extension. It was the same, also, in relation to the 

 degree of contraction, for the beam was not depressed 

 as much as when a lesser weight was in the scale. 



From these experiments, M. Schwann concludes 

 that the power of contraction is greater when the 

 muscle is least contracted, and therefore (he argues) 

 that the force of vital contraction cannot augment in 

 an increasing ratio as the particles approximate, as 

 would be the case if the law of attraction were of the 

 same nature as that of gravity, or any other physical 

 force. 



It is difficult, however, to understand by what pro- 

 cess of reasoning M. Schwann is led to this conclusion. 

 In respect to the law of universal attraction, there is 

 no doubt that bodies will move towards each other 

 with an energy increasing in the ratio of the square 

 of the distance, if these bodies are free to move ; and 

 such a law seems to be involved, of necessity, in the 

 very idea of force. When, however, the bodies acted 

 upon are not free to move, and a force of resistance is 

 opposed to that of attraction, the case is entirely 

 altered. Do away with resistance, and bodies will 



