140 THE SIGNS OF LIFE [LECT. 



former is such as would be produced by an ingoing current of 

 water through the skin, the latter by an outgoing current of 

 water. The effects appear to be similar in character to those 

 more recently pointed out by MacDonald, as regards the 

 injury current of nerve which he considers as being essentially 

 a concentration current viz., augmentation by water or by 

 dilute salt solution, diminution or abolition by strong salt 

 solution. 



82. A limitation. While it is perfectly true that blaze is 

 a sign of life, it is equally true that many assuredly living things 

 do not blaze. But at this stage, without a fuller and more 

 exhaustive examination of all sorts and conditions of living 

 matter, it would be hazardous to propound any absolute and 

 unrestricted negation. In the more familiar case of the evolution 

 of CO 2 , we know that the phenomenon is a sign of life ; but we 

 also know that many assuredly living things do not demonstrably 

 discharge CO 2 , and that the same living things may comport 

 themselves very differently under different conditions. The low 

 resistance of organs like the liver and kidney, the absence of a 

 definite membrane between our electrodes enabling living cells 

 to exercise the osmotic pressure that underlies ionic transfer, 

 are conditions obviously unfavourable to the delivery of blaze- 

 currents into an external circuit. 



Many assuredly living things have not, to such examination 

 as we have as yet made, manifested the clear and typical effects 

 familiar to us in the case of the eye, and the skin and vegetable 

 tissues. Muscle and nerves give comparatively small effects, 

 and I have even failed to obtain any trace of response under 

 similar conditions of experiment from the recently excised 

 organ of torpedo which a few moments before, in the animal 

 itself, gave me the well-known thrill characteristic of the dis- 

 charge. I have witnessed well-marked effects in frog's spawn 

 at one time, and have failed to obtain any effect at all in other 

 spawn at a different stage of development. I do not conclude 

 from this that blaze is not a sign of life ; indeed, I should be 

 reluctant, without further and closer examination by the ABC 

 method, and with shortest possible transfer time to state abso- 





