PHYSIOLOGY OF NERVE 281 



not in nerve set free electrolytes, 1 and if the preliminary 

 assumption be granted, that there are none set free by an injury. 

 This is quite consonant with the theory just stated, but presents 

 some difficulty to the concentration cell theory. Macdonald's 

 invocation of " pseudo polarisation," and his supposition that the 

 electrolytes in nerve are free to conduct electricity but not to 

 exert osmotic pressure, is an explanation that seems to require 

 a further experimental basis before it can be unreservedly 

 accepted. 



It might be supposed that the location and properties of the 

 membrane or surface of separation which divides the fluids would 

 present some difficulties. Ostwald ( 70 ) originally showed that such 

 a membrane could exist, and that it might be permeable to either 

 kations or anions, but not to both. In the case of nerve the 

 membrane would have to be permeable to kations alone, as stated 

 above. Alcock's ( 64 ) further observations on the action of chloro- 

 form showed that while the results on nerve could be taken either 

 way, the experiments on frog's skin required for their explanation 

 the presence of such membranes situated just below the outer 

 surface, and that no simple diffusion process would be sufficient. 

 So that as far as the membrane is concerned both the " concentra- 

 tion cell " and the " diosmotic " theories have some experimental 

 justification. 



Here the subject must be left as far as the present occasion is 

 concerned. For the future we may hope that further experiment 

 will enable us to decide between the present series of conflicting 

 hypotheses. 



Although we have considered the matter solely from the stand- 

 point of nerve, it is admitted that the same laws govern the life 

 of every cell in the body, and the inquiry is really a fundamental 

 one into the properties of living matter. To any one who takes 

 an interest in anything beyond the routine work of examinations 

 such inquiries cannot fail to be of the greatest importance, and it 

 is only in physiology that it is necessary to defend the acquisition 

 of knowledge for its own sake. 



1 Moore and Roaf (*) and Roaf and Alderson () have advocated the contrary 

 view as far as the action of CHClj is concerned, but the discussion is too elaborate 

 to be continued in this place. 



