34 THE PHYSIOLOGY OF MUSCLE AND NERVE. 



fall into the muscle at equal intervals the contractions show certain 

 features that, in a general way, are constant, although the precise 

 degree in which they are exhibited varies curiously in different 

 animals. Such curves are exhibited in Figs. 14, 15, and 16, and 

 the features worthy of note may be specified briefly as follows: 



Fig. 15. Effect of repeated stimulation; complete curve, showing late contracture. 

 The muscle was stimulated by induction shocks at the rate of 50 per minute. The separate 

 contractions are so close together that they can not be distinguished. 



Fig. 16. Effect of repeated stimulation, curve showing no contracture or very little. 

 The muscle was stimulated by induction shocks at the rate of 50 per minute. A very 

 slight contracture is shown in the beginning, but subsequently the contractions show 

 only a diminished extent, the rate of relaxation remaining apparently unchanged. 



1. The Introductory Contractions. The first three or four con- 

 tractions decrease slightly in extent, showing that the muscle at 

 first loses a little in irritability on account of previous contractions. 

 This phenomenon is frequently absent. 



2. The Staircase or " Treppe." After the first slight fall in 

 height has passed off the contractions increase in extent with great 



