i.] NOTA NOTM 3 



have ceased to live, how quickly they live, how much they live, 

 upon what they live, and how while they live, they absorb, 

 transform, distribute, and dispense the energy stored in food 

 and manifested in each act of life. In one word our task as 

 physiologists is to study the signs of life. To say that these 

 are lectures on the signs of Life is to say that they are lectures 

 on Physiology. 



The Signs of Life. 



The signs by which we can always recognise that living 

 matter is living are : 



r. Its reducing or deoxygenating power; 



2. Its exhalation of carbon dioxide ; 



3. Its excitability ; and 



4. The electrical signs of its chemical activity. 



The present series of lectures will be in chief measure drawn 

 from the fourth head and I should have taken for their title 

 the electrical signs of life, were it not that the electrical signs by 

 themselves should not in my opinion be divorced from other 

 signs ; and are indeed, when so divorced, of comparatively small 

 general importance matter of special and technical interest 

 rather than a chapter in General Physiology. 



The point of view to be taken can be formally presented 

 in terms of the classical axiom of the logicians nota notes est 

 nota rei ipsius inasmuch as chemical change being a sign of 

 life, and electrical change a sign of chemical change, it follows 

 that electrical change is a sign of life meaning by " sign " 

 an universal attribute of our subject rather than an occa- 

 sional or exceptional incident a " propriuui " rather than an 

 " accidens." 



From which formal position we may proceed a step further, 

 and recognise that in the study of electrical change we have the 

 most delicate and one of the most convenient means of approach 

 towards an answer to these two questions addressed to matter 

 that may be living or not-living : 



1. Are you alive? 



And when this first qualitative question has been answered : - 



2. How much are you alive ? 



