WHAT IS LIFE? 59 



be converted once more into mechanical motion by means 

 of the electric motor. The kinetic energy of a waterfall 

 may be transformed into mechanical energy by means of 

 the old-fashioned mill wheel, and we might go on in this 

 manner considering one series of transformations after 

 another. The force of a living being is different from 

 these natural forces in this, that it directs and guides the 

 natural forces to its own purposes. 



Not many years ago we did not know that cells pro- 

 duced the trees, plants and animals we see, we did not 

 know that those builders existed. When I first became 

 interested in nature and biology, we were told by the 

 scientists that the cause of plant growth was endosmosis 

 and crystallization. We know now that the plants and ani- 

 mals that we see are structures produced by smaller 

 animals we call cells. By reason of a more powerful eye 

 made partly by ourselves and partly by the cell, we can 

 see these individuals. The cell makes our eyes as nearly 

 suitable for every day use as he thinks best, but for a 

 further special use like seeing smaller things like cells, 

 or for distant objects like planets, we add to or change 

 the arrangement of the lenses of the eye to effect the 

 purpose desired. It requires just as much intelligence 

 to build the eye in the first place as to change it for any 

 special or particular purpose afterwards. The cell is not 

 a mass of matter composed of electrons, atoms or mole- 

 cules, but is a highly organized and specialized living 

 being. We shall find that he is made up of possibly 

 millions of still smaller living beings. It seems clear that 

 the only method to solve the mystery of life is to more 

 completely investigate the inner life of the cell and put 

 all the questions to him. 



It seems to me the only reason that so many ideas and 

 differences of opinion about life have arisen is the fact 



