CONCLUSIONS 101 



blaze up. It no longer reacts to a stimulus. Nearly all 

 kinds of tissues show these blaze currents as long as 

 they are alive, and the outburst is not only a sign of life, 

 but an index of the amount of life. Life and electricity 

 are inextricably bound up together. In the sea algae 

 alone Waller failed to find this blaze current, but he does 

 not doubt that it exists there. One does not obtain 

 it for the reason, probably, that the salts of the sea- water 

 close the current through the tissue rather than through 

 the galvanometer. Perhaps a low-resistance galva- 

 nometer would detect it here too. This sign of life of 

 Waller is in many ways the most convenient that we 

 have, if only we have the apparatus for the detection 

 of these currents ready at hand and set up for use. 



But up to this point we were still in the dark regarding 

 the cause of this electrical response. We could not know 

 whether it was due to a physical or a chemical change 

 in the tissues. It might be due to some change of 

 permeability of the tissues, or it might be due to a chem- 

 ical change. Waller believed it to be caused by the 

 latter, and his conclusion was undoubtedly correct. 



Waller also observed that following this electrical 

 display there was a sudden lowering in the electrical 

 resistance of the pea or other tissue. This might 

 also be called a sign of life, but it is not so clear and 

 striking as the blaze current. Evidently this is by no 

 means so reliable a sign of life as the other. The de- 

 creased resistance might be due to a physical change of 

 state of the protoplasm or of the membranes, so that the 

 salt solution became more continuous; or it might be 

 due to the stimulation increasing in some way the ions in 

 the protoplasm. It is impossible to say which. 



