THE PHENOMENON OF CONTRACTION. 37 



more precisely by direct experiments on single muscles. A frog's 



Fig. 17. To show the decrease in extent of contraction of the gastrocnemms muscle 

 of a frog with increase in load. In the first contraction, to the right, the load was 14.2 



fms. At each successive contraction the ^ad was increased by 5.3 gms. With a load of 

 82 gms. the lever gave only the slightest indication of a shortening, and this may have 

 been due to some lateral movement. 



Fig. 18. The curve of work obtained by plotting the results shown in Fig. 17. The 

 initial contraction was made with a load of 14.2 gms., and the work done in gram-milli- 

 meters is represented by the ordinate erected at this point. The maximum work was done 

 with a load of 88.6 gms., and the absolute power of this particular muscle was found to be 

 equal to 182 gms. 



muscle may be isolated and the extent of its contractions and the 

 work done may be estimated directly. Under such conditions it 



