The Demarcation Current of Mammalian Nerve. o!7 



Resistance. 



The condition of rigor is most completely produced by the action 

 of water, but in all the characteristics observed differs only in degree 

 from similar conditions produced by dilute saline solutions, e.g., 0'6 

 gramme per cent. NaCl solution. 



In the latter we get the same increased rigidity, weight, length, &c., 

 as also the diminution of conductivity ; all of these, however, are found 

 to a smaller measure, and are much less persistent. 



Although not provided with the evidence of direct analysis, it seems 

 very reasonable to assume that both the extreme and the lesser varia- 

 .tions, as judged by the character of the changes observed, are to be 

 explained by the occurrence of " osmosis " and " diffusion" ; and that 

 in the extreme case, the nerve continues to acquire water until a very 

 considerable internal pressure is produced, thereby causing the extreme 

 changes of form and elasticity, whereas the conductivity is gradually 

 diminished through an increasing loss of electrolytes by processes of 

 diffusion. 



It is worthy of note that the appearance is quite different in cha- 

 racter and degree from the slight rigidity change which ordinarily, in 

 nerves, follows the death of an animal, and that it can be produced by 

 a short immersion in tap water in a nerve removed from the body of a 

 " several days dead " dog, or in a nerve which has lain for days in 

 saline solutions, and therefore is in no way dependent upon the living 

 state of any of the structures of the nerve. Finally, as a minor proof 

 that it is not produced by the precipitation of globulins in the nerve, it 

 is completely and at once abolished by immersion in a saturated solu- 

 tion of magnesium sulphate. 



***** 



The graduated character of the changes produced and their parallel- 

 ism with the graduated concentration of the solutions has been care- 

 fully followed out ; for the sake of brevity, however, data are given 



