8 Spirazines 



that they consist of an outer cytoplasm containing 

 central bodies, asters, fibrillae, plastids, chon- 

 driosomes, Golgi-bodies, etc., and an inner nucleus 

 containing chromosomes, linin network, etc. Nu- 

 cleated cells like those which form the bodies of 

 the higher plants and animals have a definite 

 lower limit of size, being never smaller than sev- 

 eral (approximately five) microns in diameter. 

 Since the diameter of the benzene ring, as mea- 

 sured between the centers of the atoms, is about 

 three Angstrom units (3 X 10"^ cm), in diameter, 

 it would take about seventeen thousand benzene 

 rings arranged side by side to form an object 

 as large as the smallest living cell, or about 

 2,500,000,000,000 to fill the volume thereof. It is 

 probably safe to say that a structure of such com- 

 plexity could never have sprung into existence 

 spontaneously from inorganic substances. The 

 conclusion is therefore inevitable that the typical 

 nucleated cell does not represent the most primi- 

 tive form of life, but is probably the final result 

 of a long process of evolution. 



A much more primitive form of life is exhibited 

 by the bacteria which carry on the same processes 

 of metabolism and pass through the same cycles 

 of growth and cell division as their nucleated 

 relatives, so that they must be regarded as true 

 living organisms. These differ from nucleated 

 cells in that they are definitely smaller in size, are 



