4 THE SIGNS OF LIFE [LECT. 



3. Instances. The two instances of electrical effects with 

 which you are no doubt familiar already, are : 



i. The negative variation of muscle; 2. The negative 

 variation of nerve : and I shall presently use the first of these 

 phenomena to illustrate the parallelism between the mechanical 

 sign of life (contraction) and the electrical sign of life (negative 

 variation). 



Turning now to the syllabus of this first lecture, you find 

 there several headings that are more or less familiar to you, that 

 I shall nevertheless recall to your attention, for the sake of the 

 point of view I ask you to take. 



Omitting any attempt to define " Life and the Living State," 

 we shall in first resort seek to recognise what are the principal 

 differences between matter that is alive and matter that is not- 

 alive. And take note in passing that by this division into alive 

 and not-alive, or living and not-living, we include dead matter 

 as a sub-division of not-living matter, which we consider as falling 

 into the complementary sub-classes of matter that has previously 

 lived (but is now " dead ") and matter that has not previously 

 lived (and is called " inert "). 



And although our physiological problems are in most cases 

 concerned with the comparisons and distinctions that we are 

 able to institute between living and dead matter, we shall find 

 for the sake of logical discourse in dealing with matter in a state 

 of what has been called latent life or suspended animation that 

 it is convenient to make a first division into living and not-living, 

 and a sub-division into dead and inert in accordance with this 

 dichotomous scheme : 



Matter. 



This scheme has been drawn up with the particular purpose 

 of showing how, in my opinion, we should logically deal 



