PHENOMENA OF MUSCLE AND NERVE. 299 



The striking result of this experiment led to a method by 

 which the different effects dependent upon direction of current 

 were still more markedly shown. It is seen above that (at least 

 within the limits of current strength there employed) currents 

 directed from dead to living tissue hardly ever give the + phase, 

 which only appeared with a current directed from living to dead 

 tissue, the arrangement being that one leading-in and one leading- 

 off electrode lie in the region of artificial cross- section ; further, 

 that with currents directed from living to dead tissue the appear- 

 ance of the + phase is favoured by the proximity to the anode of 

 the electrode leading off the living tissue. Could this latter be 

 identified with the anode, the conditions for the production of the 

 phenomena would be the most favourable. 



This is obtained in the gastrocnemius, for instance, when a 

 thermal cross-section is made in the upper end by dipping it into 

 hot water. Upon this one leading-off and one polarising electrode 

 are placed, and then the other leading-off and the other polarising 

 electrode are placed upon the Achilles tendon ; both places offer suf- 

 ficient room for two kaolin points. With this arrangement the de- 

 scending (dead to living) current never gives the + phase ; on the 

 other hand, the ascending (living to dead) current gives it even 

 when quite weak. The state of things is evidently this ; the lead- 

 ing off occurs quite at the anode and kathode, independently of the 

 direction of the current. The anode, however, in the case of 

 a descending current, lies upon the artificial cross-section ; ac- 

 cordingly it is only with ascending currents that the + phase is 

 produced. 



But it is possible to go still farther. So far the union of a 

 leading-in and a leading-off electrode has been effected by a part 

 of the muscle which acts as an indifferent conductor, whether 

 this be the tendon or a portion of tissue in heat rigor. There 

 is however no objection to effecting this by a piece of electrode 

 kaolin. This is indeed capable of internal polarisation according 

 to du Bois-Reymond, but only ' negatively ; ' and at any rate 

 it can scarcely be more polarisable than a piece of tendon or dead 

 muscle. 



When it is desired to lead off from the entire portion of tissue 

 through which the polarising current passes, a very simple arrange- 

 ment is the following ; the kaolin points of the leading-off elec- 

 trodes are laid upon the tissue, and upon these points are placed 

 those of the polarising electrodes. The * external ' polarisation 



