iv.J WHY "BLAZE-CURRENTS?" 73 



traversed by violent currents will exhibit changes outside the 

 polar area in general accordance with ordinary current-diffusion. 

 But for all moderate strengths the blaze reaction of a living skin 

 or of a living leaf is strictly local. 



These experiments have been troublesome to follow, as they 

 have been troublesome to demonstrate, and we may perhaps find 

 it a relief from a somewhat absorbing effort of attention, to turn 

 to an academic discussion, touching the nomenclature of these 

 phenomena, and their relation to other known phenomena, and 

 their conceivable biological significance. 



46. I have been asked why I chose to designate the effects 

 by the name of " blaze-currents " rather than " positive polarisa- 

 tion currents," or "post-anodic action currents." I think you 

 will readily understand the answer to the negative parts of this 

 question. Apart from the fact that the name " positive polarisa- 

 tion," as first used by du Bois-Reymond to designate certain homo- 

 drome effects observed by him in muscle, nerve, and electrical 

 organs, has been adversely criticised by Hermann and Hering 

 shown by them, indeed, to be a misnomer inasmuch as the 

 effects to which it was applied are demonstrably due to post- 

 anodic action current I think it is sufficient to refer to the 

 equivocal or antidrome blaze as forbidding the use of the term 

 " positive polarisation." The use of the term " post-anodic 

 action currents " you have just seen to be altogether unjustified 

 for these skin-currents ; in one case the current is not post-anodic 

 at all, and in the other it is post-anodic, but of opposite elec- 

 trical sign to that of a post-anodic state. In muscle and in nerve 

 a post-anodic spot is galvanometrically negative ; in the skin it 

 is galvanometrically positive. So that both these cumbersome 

 expressions are happily inapplicable, and a new term is required. 

 I have been led to adopt the term blaze-current, and I think 

 you may now understand how it arose in the study of retinal 

 effects, and how it serves to clearly earmark a natural group of 

 phenomena of very definite physiological meaning. 



A blaze-current is literally and strictly a " current of action " ; 

 but it is a particular kind of action current, and requires a dis- 

 tinctive name. The known phenomenon to which it bears most 



