4 8 



one stage of the degeneration which follows separation from its 

 nerve, the anodal closing contraction (fig. 18, Anode M) becomes 

 much exaggerated. This is called the reaction of degeneration. 



When muscle is stimulated by induced electricity (fig. 20) 



Electric 

 Current. 



Make. 



Break. 



Make. Break. 



Contraction 

 of Muscle. 



Kathode. 



Anode. 



Kathode. Anode. 

 Galvanic. Induced. 



FIG. 19. To show separation of make and break stimuli and of anodal and 

 kathodal effects when a galvanic current is used, and their combination 

 when the induction coil is used. 



the question is much easier, for, with each make and break or 

 each sudden alteration in the strength of the primary circuit, 

 there is a sudden appearance and 

 equally sudden disappearance of a 

 flow of electricity in the secondary 

 coil. If, therefore, wires from the 

 secondary coil are led off to a muscle, 

 each change in the primary circuit 

 causes the sudden and practically 

 simultaneous appearance and disap- 

 pearance of an electric current in the 

 muscle, and this of course causes a 

 contraction. But here the effects of 



FIG. 20.-Course of Electric clogi an( j opening the current are 

 Current 111 primary circuit . r 



(lower line), and in second- practically f used, and hence the mnu- 



ary circuit (upper line) of 

 an induction coil. Observe 

 that in the secondary the 

 make (upstroke) and break 

 (downstroke) are combined, 

 and that a stronger current 

 is developed in the second- 

 ary circuit upon breaking 

 than upon making the 

 primary circuit. 



ence of the anode and kathode, and 

 of closing and opening, need not 

 be considered (fig. 20). (Practical 

 Physiology.) 



It must, of course, be remembered, 

 that in an induction coil the opening 

 of the primary circuit produces a 

 more powerful current in the second- 



