294 THE SO-CALLED SECONDARY ELECTROMOTIVE 



The striking- result of this set of observations made me think 

 that the different iniiuence of the anode and kathode respectively 

 might be more markedly obtained by uniting- one of the leading- 

 off electrodes with the anode or the kathode of the polarising 

 current. This method, if literally carried out, would involve the 

 danger of bringing in external polarisation (in the electrode itself), 

 but naturally it is only necessary to make the physiological 

 electrodes identical, i. e. the points of connection of the battery 

 and of the galvanometer with the muscle fibres ; and to do this I 

 proceeded as follows. 



A gastrocnemius was stretched out by means of my extension 

 arrangement, and a polarising current led in at the Achilles tendon 

 and the knee-end. One of the leading-off electrodes was also placed 

 on the Achilles tendon somewhat above the leading-in electrode, 

 the other lay on the surface of the muscle at about the junction of 

 the lower and middle thirds of the fleshy part. It is evident that 

 with an ascending current the lower ends of the muscle fibres con- 

 stitute the physiological anode and that it is here that the lower lead- 

 ing-off electrode is in contact with the muscle substance, whilst the 

 upper leading-off contact lies far removed from the physiological 

 kathode ; with a descending current the physiological kathode and 

 lower leading-off contact are identified. 



The expected result was most beautifully brought out. With de- 

 scending currents, deflections only were almost always obtained ; 

 with ascending currents, diphasic ( h) deflections or + alone. 

 Moreover, now even with one zinc-carbon cell the + phase showed 

 itself ; whereas with the ordinary method at least two or three cells 

 were needed. It may therefore be stated that leading-off at the anode 

 itself is the most favourable, at the kathode itself the least favour- 

 able condition for obtaining the 4- intrapolar after-effect. 



Example I. (Left hand.) Gastrocnemius led in and off as just 

 described. Current of rest tgiS scale = 0-0033 D. (In the course 

 of the experiment the current of rest due to the summing up of 

 the residual -f phases with ascending polarising currents increased 

 to five times this amount ; this increase showed itself in all the 

 experiments.) 



Example 2. (Right hand.) Gastrocnemius as above. Current of 

 rest I 32 (delicacy diminished) = 0-0065 D. (Increased during experi- 

 ment to 4! times as much.) 



