238 



ELECTRIC CURRENT. LrECT. XII. XIII. 



one, but that it acts in a directly opposite way; namely, that 

 whilst the direct current diminishes the excitability, the 

 inverse current augments it. 



Fig. 18. 



Three views of Bregaet's Apparatus for measuring the Contraction of Muscled 

 produced by the Electric Current. 



If the nerve be traversed for several hours, say three or 

 four, by the inverse current, it frequently happens that at 

 the interruption of the circuit, the limb suffers a very vio- 

 lent contraction which lasts for a certain number of se- 

 conds, and might, therefore, be termed tetanic. This 

 phenomenon ceases when we again close the circuit ; but 

 it is important to observe, that at the moment when we 

 thus close it> there is a fresh contraction, after which the 



