72 life's beginning on the earth 



The fractions given above with all their zeros do not 

 readily confer a vivid conception of the size of an indivisible 

 particle. The following comparison may be helpful: there 

 are more molecules in a single drop of water than there are 

 drops of water in the Atlantic Ocean. Another comparison: 

 if each molecule in a glass of water became a grain of sand, 

 the sand produced would cover the entire area of the United 

 States to a depth of 100 feet. 



For different materials the size of the smallest particles 

 is, of course, not identical. Those of carbon compounds 

 are larger than those of water, in keeping with the larger 

 size of their atomic structure (see pages (11 and 62). 



7. THE VIRUS IN CHEMICALLY PURE FORM AND ITS 



CRYSTALLIZATION 



We have learned from the foregoing descriptions that 

 size alone is no criterion of living or non-living matter. 

 One might draw the dividing line between living and non- 

 living at any chosen level, for instance by pronouncing alive 

 only creatures of the size of a horse or larger. In that event 

 we human beings would not be alive. Unexpected findings 

 should never discourage our patient search for truth. A 

 faithful student of nature will learn more from startling 

 discoveries than from those findings which were partly an- 

 ticipated. And indeed we arrive at new important con- 

 clusions if we follow the fundamental fact that a shapeless 

 mass may consist of a multitude of invisibly small living 

 things. 



We may raise the following question: what will occur if 

 any one of these virus materials is freed from all other 

 material mixed with it? That is to say, if the virus is 

 "purified chemically," as it is usually expressed? .Most 

 "pure" substances tend to crystallize, if they are solid. 

 Two everyday examples illustrating this are ordinary white 

 cane sugar and table salt, both of which arc in the form of 



