Introduction 



The transformation of non-living matter into the multitudinous 

 forms of living plants and animals, from the visible to the ultra- 

 microscopic, is one of the least comprehensible of all natural 

 phenomena. In this book an attempt is made to explain the basic 

 mechanism of life and its processes in terms of better known and 

 more readily grasped concepts. Life is so usual, so widespread, so 

 persistent, that it peculiarly justifies the motto which hangs on the 

 wall of a large research laboratory: 



THIS PROBLEM, WHEN SOLVED, WILL BE SIMPLE 



For nature, not limited by our experimental or mental capabili- 

 ties, solves directly and with ease the most complicated problems 

 submitted to her. Man spends years in endeavoring to discover 

 and comprehend her operative mechanisms, in the hope that he 

 may mold them nearer to the heart's desire. 



Though science properly demands that we should accept only 

 what we can unequivocally demonstrate, it is unscientific to con- 

 demn a view simply because we cannot check it experimentally 

 with methods at present known. The future has always brought 

 new methods, new light, new insight. Napoleon's clever but 

 sometimes untrue statement — history is a lie, agreed upon — 

 points up the fact that science has sometimes accepted, taught and 

 dignified notions later proven to be erroneous — for example, the 

 indivisibility of the atom, and the belief that all atoms of every 

 element are precisely alike. 



The chemist and the physicist, starting with the many kinds of 

 atoms and more recently with the fewer kinds of sub-atomic par- 

 ticles, have been working their way upward into larger aggrega- 

 tion units, the molecules, and into the still larger macro-molecules, 

 chain-molecules, molecular groups, and colloidal particles. On 

 the other hand, biologists in their various fields have been steadily 

 working downward to smaller and still smaller units in the cell 

 and "protoplasm," once naively spoken of as "the living jelly." 

 These two groups of investigators have been drilling a tunnel 

 through the mountain of ignorance from opposite directions, and 



