A TEXTBOOK OF PHYSIOLOGY 



it will be found that the amount of work done at first increases 

 with the load, and then diminishes, giving a '' curve of load." The 

 actual height through which the weight is lifted is obtained by dividing. 



FIG. 283. FATIGUE: FROG'S GASTROCNEMIUS. (AValler.) 



Direct excitation; 125 successive maximal contractions at intervals of 1 seconds,, 

 showing at the outset increase of height and of duration, later decreasing height. 

 The exhaustion has not been pushed to the end. 



the height of the curve by the magnification due to the recording 

 lever. For purposes of " load " experiment, it is better to use the 

 form of apparatus shown in Fig. 273, since the load can then le 

 applied clirectty below the muscle. 



l-'iu. 284. FATIGUE CURVES OF K, SARTOKIUS MUSILE IN KIMJER'S .SOLUTION; 



-\RTORIUS AFTER FlFTEEN-MlNUTE IMMERSION IN GfANIDIN O'l PERCENT. 



SOLUTION. (Caniis.) 



Tin -e in ?econd?. The staircase effect is seen and also the depressant effect of guanidio 



in high concentrations. 



Previous Activity. When curves are taken from a perfectly fresh 

 muscle preparation, the first few may show an improvement in the 

 degree of contraction. This is known as the " staircase effect," and 



