94 C. M. CHILD. 



rate and amount of reduction are associated with and dependent 

 upon the living condition and disappear, either with, or soon 

 after, death. 



CONCLUSION. 



Since KMnO4 is a powerful oxidizing agent, the inference is 

 justified, as I have pointed out elsewhere (Child, '19^), that the 

 rate and amount of reduction of permanganate by living proto- 

 plasm is in some way and to some degree related to oxidative 

 activity in the protoplasm. This inference is apparently sup- 

 ported by the marked decrease in reducing capacity of the 

 protoplasm with death and the disappearance with, or soon after 

 death, of the regional differences or gradients in rate and amount 

 of reduction. Moreover, the reduction gradients are essentially 

 the same as the susceptibility gradients and many different lines 

 of evidence indicate that the latter are, at least to some extent, 

 associated with and dependent upon differences in rate of oxida- 

 tion (Child, '20). The results obtained with permanganate are 

 then in complete agreement, as regards the existence of physio- 

 logical gradients, with those obtained by other methods and 

 constitute another line of evidence in support of the general 

 conception. 



The question of the role of permeability in relation to the 

 reduction gradients must be raised. It has been repeatedly 

 pointed out (Child and Hyman, '19, Child, '20) that gradients 

 in permeability are in many, if not in all cases, characteristic 

 features of the physiological gradients, but many facts show 

 clearly enough that the fundamental metabolic activity of the 

 protoplasm is also concerned in these gradients. We are forced 

 to conclude, either that the gradients are not simply permeability 

 gradients, or else that permeability and the fundamental meta- 

 bolism of the protoplasm are very intimately associated and more 

 or less interdependent. As regards the reduction gradients, it 

 may seem at first glance that the differences in rate of reduction 

 are merely the result of differences in permeability to permanga- 

 nate. This is perhaps to some extent the case, but observation 

 indicates that these differences appear first upon the external 

 surface of the protoplasm. It is not necessary that the per- 



