152 LOCALIZED ELECTRIZATION. 



Oiiimus and Legros ; and show that, in equivalent doses and under 

 similar conditions, the continuous constant and the induced cur- 

 rents, when passed through the great sympathetic, exert an iden- 

 tical action upon the vaso-motors. 



Experiments. — A'continuoiTS constaut current (from a pile of from fifteen 

 to tliirty sulphate of lead elements) passing through the sympathetic in a 

 portion three or four millimetres below the superior cervical ganglion, pro- 

 duced a slight but manifest contraction of the vessels, and a decoloration of 

 the ear on the same side, during the whole time of the experiment. 



When the sympathetic nerve had previously been strongly excited, or, in 

 other words, when its excitability had already been more or less exhausted, 

 as by the passage of a powerful induced current, or by section, the same 

 continuous current of thirty elements, or even of fifteen, produced, instead 

 of contraction of the vessels, their dilatation during the whole time of the 

 experiment. 



An extremely weak induced current (the minimum of the extra current 

 of my volta electric apparatus, jiassed through a column of distilled water 

 twenty-two centimetres in height), and localized in the sympathetic in the 

 same manner for three minutes, produced a. slight contraction of the vessels 

 of the ear during the first half minute, followed by dilatation during the 

 rest of the experiment. 



The same proceeding, repeated upon the sympathetic of a rabbit that had 

 been subjected to a strong induced current for three minutes, an hour pre- 

 viously, but in which the ear had regained its normal vascularity, immediately 

 produced dilatation of the vessels which rendered their finest ramifications 

 visible for three minutes. 



■ A strong induced current passing in the same manner through the sym- 

 pathetic of a rabbit, whether it had been the subject of previous experiment 

 or not, produced, during the whole time of its passage (three minutes), a 

 considerable shrinking of the vessels ; followed, when the current was with- 

 drawn, by an enormous and long persistent dilatation. 



Interrupted galvanic currents passed through the great sympathetic acted 

 upon the ganglionic vaso-motors in the same manner as induced currents. 



It follows from these experiments : — 



That a continuous constant current, directed upon the exposed 

 great cervical sympathetic of a rabbit, the excitability of which 

 has not been exhausted (neither by electrization in prior experi- 

 ments, nor by manipulations, nor by long exposure to the air), 

 produces, like an induced current of equivalent {i.e. very feeble) 

 strength, a slight contraction of the vessels that are controlled by 

 the nerve. 



That the same current, acting with equivalent force upon a 

 nerve already exhausted, can no longer produce contraction of 

 vessels, but only moderate dilatation. 



That a powerful induced current, localized in the sympathetic, 

 produces a considerable contraction of the vessels, followed, after 

 the experiment, by enormous and protracted dilation ; and that a 

 poweriul intermittent galvanic current acts in the same manner. 



Finally, as a corollary to the foregoing, that, contrary to certain 

 statements, the continuous constant currents and the induced 



