220 



MUSCLE. 



further increase it is diminished. Usually the top of the 

 curve is markedly flattened. 



2. As an afterload. The experiment is fitted up in the same 

 way as the last, with the exception that the spring is detached from 

 the rod, and the latter is employed as a rest for the recorder, as in 

 Eig. 40, 2. The muscle should be extended without stretching, so that 

 the muscle may have no slack to take up at the beginning of its 

 contraction. 



A 



FIG. 40. 



1. Arrangement for after-loading-. R Muscle recorder. M Muscle. B Side bar 

 C Clamp holding the supporting rod. 



2. For Isometric method. S Spring fastened to rod clamped to the side bar. 



First load with 10 grammes, stimulate, and when the 

 relaxation is over after the contraction turn the drum by 

 hand for half a cm. 



Load with an additional 10 grammes for each successive 

 contraction until all have been added. 



The curves as compared with those obtained in the last 

 experiment are much less in height from the first, undergo 

 less increase, and subside sooner. 



The muscle is more extensible under increasing loads, and 

 consequently there is more and more " slack " to take up 

 after each increment of weight is added, hence the delay 

 in raising the recorder. 



