EARLY HISTORY OF LIFE 



55 



IN REVIEW 



This discussion of the physical and chem- 

 ical properties of protoplasm may seem un- 

 duly long and to belong more properly in 

 a book of chemistry or physics. It is none 

 the less basic to an understanding of life. 

 Let us summarize briefly to emphasize this 

 once more. 



We have seen that protoplasm consists 

 of molecules, atoms, ions, and colloids no 

 different in constitution from similar enti- 

 ties existing in the inanimate world. How- 

 ever, their intricate and complex association 

 in protoplasm bestows upon them the prop- 

 erties that we assign to living things. Al- 

 though some of the properties of these par- 

 ticles have been described, certainly not all 

 of them have been, nor could they be, 

 because they are not known. 



Many people have attributed to proto- 

 plasm a vague sort of "something" called 

 life, that suddenly leaves a living thing 

 when it dies. However, attractive though 

 this may be, it is no explanation, at least in 



the scientific sense. The reason whv we have 

 difficulty in explaining life is because we do 

 not know enough about the intricate work- 

 ings of molecules, atoms, ions, and other 

 particles that go to make up protoplasm. 

 If we had sufficient knowledge about their 

 behavior perhaps we could explain how 

 protoplasm is put together and exactly how 

 it works; indeed, we could explain life it- 

 self. That is a far distant goal, but one wor- 

 thy of the most intensive research. 



Can we define life? Perhaps we are some- 

 what closer to a definition of life than we 

 were at the beginning of this discussion 

 some pages ago. We can make a few state- 

 ments but they need to be shrouded in vague 

 terms which we still do not quite under- 

 stand. Certainly life involves motion and in- 

 teraction of particulate matter at size levels 

 from atoms to huge colloids. It includes 

 ceaseless chemical change, with its concom- 

 itant consumption or release of energy. 

 Life means chemical and physical organiza- 

 tion of pattern and design with a never 

 ending trend toward greater complexity. 



