CURRENT OF DEATH 173 



of a strong excitatory reaction. This corresponds with the 

 rigor mortis of the animal, and by means of suitable 

 apparatus, the concomitant mechanical response can be 

 recorded. An electrical record of the same phenomenon 

 may also be obtained, in the form of an electrical spasm of 

 galvanometric negativity. Succeeding to this rigor of the 

 dying tissue, a post-mortem relaxation takes place, with 

 a concomitant change from galvanometric negativity to 

 positivity. 



Now in a tissue which has been killed unilaterally only, 

 it will be understood that all possible gradations are to be 

 expected. Passing from the completely dead to the fully 

 alive, we must necessarily pass through various zones, 

 beginning with the abnormally relaxed, through the inter- 

 mediate highly contracted and rigored tissue on the death- 

 frontier, to the living, which is not so contracted as the 

 dying, and not so relaxed as the dead. At the point 

 where the onset of death . is recent, the rigor, or excitatory 

 contraction and galvanometric negativity, are at their 

 maximum. Compared with this, the slightly tonically con- 

 tracted living is positive, but not so positive as the abnormally 

 relaxed dead. 



The death-frontier, however, is not fixed. It is con- 

 tinually encroaching on the living. The line of maximum 

 rigor and galvanometric negativity is thus also shifting in 

 the same direction. Along with this, however, the opposite 

 process of post-mortem relaxation is proceeding ; so that a 

 point which was, in consequence of rigor, maximally negative, 

 becomes gradually converted to positive. 



This positivity of dead tissue as compared with living, 

 which has here been demonstrated in the case of the plant, 

 I find to be also true of animal tissue, in those cases which 

 I have investigated. Thus, while an injured and dying area 

 in a frog's nerve is negative, an already dead area is 

 positive, relatively to the living nerve. There is, moreover, 

 an intermediate area, between the dying and dead portions 

 of the nerve, which is iso-electric to the living. 



