280 SOME CHAPTERS ON THE 



so that to produce a current in the right direction diffusion must 

 be supposed to be faster down the nerve than into the electrodes. 

 Finally, as the difference in velocity of the two ions is so small, 

 and as the E.M.F. is the difference of the diffusion into electrodes 

 and nerve, a very high concentration is needed according to the 

 " concentration law " equal to 10 per cent. KC1 yet the chemical 

 analysis of the tissue (as far as the observations go) shows that 

 even if all the K and Cl be supposed to be present in the axis 

 cylinder and none elsewhere, there is not enough to give a con- 

 centration of more than -5 per cent, at the outside. 



III. The theories based on fluid cells are at first sight more 

 promising, especially as it has not yet been possible to give exact 

 details which can be put to the test of direct experiment. 



The view of Brunings ( 66 ), perhaps the best instance of this 

 theory, is that animal electricity in general, and nerve in par- 

 ticular, is an example of a " diosmotic cell." This is an arrange- 

 ment by which two fluids, which may be of the same osmotic 

 pressure but differ in composition, are separated by a membrane, 

 which is impermeable to both fluids as a whole, but permeable 

 to at least the kation of the fluid lying within the cell. Such an 

 arrangement would give a current on fracture of the membrane, 

 would not give heat externally, would show the same osmotic 

 phenomenon as a nerve, and does not require a greater concen- 

 tration of electrolytes than is met with elsewhere in the body. 1 

 The electrolytes are supposed to be " preformed " ; they might be 

 adsorbed on the surface of protein molecules or not. 



Alcock ( 64 ) has published some results on the electrical con- 

 ductivity of nerve before and after chloroform and ether anaesthesia 

 which bear on the question, if the assumption is made that these 

 agents produce a maximum injury. As both drugs cause an 

 electrical effect of the same sign as the injury current and of the 

 same order of magnitude this is not an unreasonable hypothesis. 

 The result is that in nerve there is no alteration of conductivity 

 (within 2 per cent.), while there is a marked diminution in the 

 polarisation. 2 The inference from this is that chloroform does 



1 Alcock and Lynch (*) give the figures for chlorine in nerve fibres. Some 

 unpublished results on the potassium content support the view given above, but 

 the experiments are still too few in number to justify the pronouncement of a final 

 opinion. 



2 Waller (* 7 ) had previously observed the alteration in polarisation. His' results 

 do not contradict those of Alcock, as Roaf and Alderson (") suppose. 



