THE CONTRACTION OF MUSCLE 543 



be stated that the shorter the whole period of the muscle twitch, the 

 shorter the latent period, and vice versa, 



The Period of Contraction is the period during which the muscle 

 shortens until the maximum shortening is reached. It is the period 



FIG. 278. VERATRIN CURVE. (Waller.) 



of rising energy. In graphic curves, this is represented as too long, 

 since the recording lever owing to inertia tends to rise too high. 

 This can be demonstrated by arresting the lever at different heights 

 during the process of contraction. At a certain point before the 



FIG. 279. THE EFFECT OF TEMPERATURE UPON THE CONTRACTION OF THE 

 GASTROCNEMIUS MUSCLE. (Pembrey and Phillips.) 



The time is marked in yj^ second. The tracing should be read from right to left. 

 Figures on curve are the temperatures of the salt solution. 



summit of the curve is reached it will be found that the lever as 

 soon as it touches the arresting body, immediately starts to fall. 

 That point marks the true height of the contraction (Fig. 277). 



Trie difference in the contraction time of different muscles is 

 mainly due to difference in anatomical structure. The quickhr con- 



