38 



THE MUSCLES 



always cease with life. In man, after death from cholera, 

 automatic movements of hands and feet have been observed, 

 lasting not less than an hour. In certain cold-blooded animals, 

 as the turtle, contraction has been known to take place for 

 several days after the head has been cut off. 



10. The property which, in muscle, enables these movements 

 to take place is called contractility. If we grasp a muscle while 

 in exercise (for example, the large muscle in the front of the 



FIG. 16. VIEW OF KNEE-JOINT. A, Thigh-bone ; B, Knee-pan ; C, D, Leg-bones 



arm), we notice the alternate swelling and decrease of the 

 muscle, as we move the forearm to and fro. It was at one 

 time supposed that the muscle actually increased in volume 

 during contraction. This, however, is not the case ; for the 



necessary for the tones they are to give. The half of a millimetre, more 

 or less, greatly changes the accuracy of the note ; and a chord a milli- 

 metre out of place produces a note which even the unpractised ear can 

 recognize as false. But the fingers fall upon the strings at precisely the 

 point required. They run over them, succeeding each other with giddy 



10. What is contractility ? How may the contractility of muscles be seen ? 



