io i A CBSMJCAL SIGN OF LIFE 



The chemical sign of life which we now propose for 

 acceptance is in many ways more fundamental than the 

 electrical. It is probable, as Waller suggested, that 

 the chemical changes underlie and produce the electrical, 

 and they produce the functional changes, such as the 

 movements which follow the excitation. In the chemical 

 changes, then, we seem to be dealing with something 

 more fundamental than when dealing with the electrical, 

 although, if we admit that all processes of oxidation are 

 in reality electrical, this distinction cannot be sustained. 

 Wherever Waller has been able to show the electrical 

 sign of life, we can show the chemical sign, and we can 

 show life at some points where he could not, as in the 

 case of the sea algae. These, under our method, respond 

 in the same manner as do all other forms of living matter. 

 Moreover, we can use this method where it is impos- 

 fcible to use the electrical; for example, in very minute 

 forms of living things, like eggs of small size, bacteria, 

 or infusoria. Our method can make it clear that they 

 are alive and breathing and responding to changes in 

 their environment like every other living thing. It 

 appears, then, that this sign of life has also certain 

 virtues of its own, although it is not so striking and 

 elegant as the method of Waller. It is also not so easy, 

 perhaps, for the ordinary man to set up and work 

 this apparatus as a galvanometer. But what it lacks 

 in ease it makes up in precision, in the quantitative nature 

 of its results, and, above all, in its fundamental char- 

 acter. By it we get as near as we have yet got to life 

 itself. 



In still another way the results which are recorded 

 here are of a most fundamental character, for one of the 



