1 8 VITAL PO WER NO T FOR CE. 



its nature essentially different from every form or mode, 

 or mood, of ordinary inorganic force. 



It must, however, be conceded by those who accept the 

 physical doctrine of life that no one has yet succeeded 

 either in obtaining vitality from the forces of inorganic 

 matter, or in converting vitality into any one of these. But, 

 nevertheless, they affirm that it will eventually be proved 

 that life is ordinary force. 



It is very important to decide what in the present state 

 of scientific knowledge ought to be understood by the word 

 " life." Is " life " but a modified form of heat or motion, 

 or some power quite distinct from physical or chemical 

 force? Or is "life" made up of physical and chemical 

 actions, and actions distinct from these (vital actions)? 

 Again, does the " life " of one of the higher animals com- 

 prise phenomena distinct in their essential nature from 

 those which make up the "life" of a monad? Do the 

 vital actions going on in the latter approach more nearly to 

 the phenomena occurring in the inorganic world than the 

 actions which constitute the " life " of the former ? 



Never were such questions more intensely interesting 

 than at this present time, never could they have been 

 investigated with greater hope of success. 



In considering a problem so vast and so difficult of 

 solution, it would seem most natural to begin with the 

 lowest, simplest living things, and advance from these to 

 the consideration of the higher and more complex, to 

 inquire first what goes on during the life of a monad or a 

 microscopic fungus, or a single cell of one of the tissues 

 and then attempt the discussion of more complex changes. 

 Instead of proceeding thus, however, many who express most 



