THE PHENOMENON OF CONTRACTION. 37 



yielded by the material oxidized in the body may take the form 



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

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

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

 182 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. 



of external work. When the muscular work performed was effected 

 by the muscles of the arms and upper part of the body, as in turning 



