72 



THE PHYSIOLOGY OF MUSCLE AND NERVE. 



Fig. 27. Engelmann's artificial muscle. The artificial muscle is represented by the cat- 

 gut string, m. This is surrounded by a coil of platinum wire, w, through which an electrical 

 current may be sent. The catgut is attached to a lever, h, whose fulcrum is at c. The catgut 

 is immersed in a beaker of water at 50 to 55 C., and "stimulated " by the sudden increase 

 in temperature caused by the passage of a current through the coil. (After Engelmann.) 



Fig. 28. Curve of simple contraction obtained from an artificial muscle. The dura- 

 tion of the stimulus (heating effect caused by the current) is shown by the break in the 

 line beneath the curve. 



and the phase of relaxation takes place. He has supported this hypothesis 

 by microscopical observations upon the relations of the dim and light bands 

 in the contracted and relaxed fibrils (p. 20), and, moreover, has constructed 



