34 THE ORIGIN OF LIFE 



up, thus exhibiting the process which we call meta- 

 bolism. 



Life, using the word in the way defined, is thus a 

 series of metabolic actions, which in a higher sense 

 would constitute fermentations, and at the same time 

 be most distinctly a specialised 'mode of motion. 



When we deal with catalytic actions we may be 

 understood to use the term vitality in what may 

 appear to be its most far-fetched and extended sense. 

 Nobody would have been justified in regarding mere 

 catalytic chemical reactions as processes equivalent 

 to the most elementary life, unless such processes in 

 some form or another could be found to give rise to 

 higher or more complex reactions that exhibit some 

 of the other properties which are associated with 

 vitality. Thus, as in the case of radium and some 

 other bodies which can produce in suitable chemical 

 compounds bodies that undergo cyclic change, the 

 evidence that they constituted some extremely ele- 

 mentary beginning of life is not so far-fetched as 

 might at first be imagined. If biogenesis is strictly 

 true, and if these forms are living things, then those 

 simple metabolic changes are also logically vital 

 actions in their simplest and most elementary sense. 

 No argument more forcible need be adduced to 

 emphasise the continuity of such actions. Life with 

 all its complex interactions, if mechanical, is surely 

 most obviously mechanical when thus stripped one 

 by one of all, or most, of its mysterious properties, 

 as we find them. Dropped one by one, till, having 

 found the simplest reactions in their very lowest 



