360 INHIBITION BY EXCITATION AND 



a matter of indifference as regards the positive kathodic polarisation 

 which results from the excitation. I observed the strongest positive 

 kathodic after-currents uniformly, after the local action of con- 

 centrated solutions of soda salts (especially Na Cl. and Na 2 CO 3 ) 

 on the kathodic end of the muscle. Mechanical injury by crushing 

 has a decidedly feebler effect, and still more unsatisfactory is local 

 treatment with dilute solutions of potash salts, by which the ex- 

 citability is at once speedily and considerably impaired. It is well 

 known, that the soda salts named, strongly excite the muscle 

 substance at the commencement of their action, or at least increase 

 its excitability. Now when they are applied locally, a slow distribu- 

 tion of the salt solutions takes place owing to diffusion ; the first 

 effect must therefore be to bring fresh sections of the muscle in 

 the vicinity of the demarcation surface successively into a condition 

 of excitation. It is evident that under these circumstances the 

 conditions for the development of positive kathodic after-currents 

 are most favourable. Thus it is precisely in the first period after 

 killing the kathodic fibre ends by concentrated solution of common 

 salt, when the demarcation current which it produces is still in the 

 act of slow increase, that we usually see the strongest positive effects. 



The capability of such a preparation of yielding positive after- 

 currents which can be led off from the kathodic half of the muscle, 

 under the given conditions, is moreover a very persistent one, and 

 continues, though in diminished degree, even after prolonged 

 washing with dilute salt solution. The muscle then (after a quarter 

 to half an hour), on its electrical excitation, often shows a behaviour 

 quite similar to that after local poisoning with veratrine: thus 

 after a battery current, atterminally directed, has been closed for 

 the shortest possible time, on leading off from the kathodic half, 

 there is at first a very strong deflection in the direction of an 

 increase of the (compensated) demarcation current, that is a negative 

 polarisation, but a moment later, the same stimulus produces a 

 more or less strong positive polarisation. (See above, Table 9.) 



In all cases, in which after the death of the muscle at one end, 

 positive kathodic polarisation prevails over negative kathodic with 

 atterminal direction of the current, it can always be shown that 

 with an abterminally directed exciting current, an exactly opposite 

 reciprocal relation exists between the positive and negative anodic 

 after-currents, the negative invariably predominating. 



I hardly need to emphasise further, that in none of the cases 

 before us were any considerable differences of tension in the con- 



