CHAPTER III 



THE UNICELLULAR MICRO-ORGANISMS THE OLD- 

 EST AND STILL THE LARGEST DIVISION OF THE 

 LIVING KINGDOM 



AFTER the discussion in the previous 

 chapter of the subjects of Reproduction 

 and Heredity, we now can properly allude 

 to the subject of Abiogenesis, which means 

 either the spontaneous or artificial genera- 

 tion of life from non-living sources. Some 

 experimenters have seemed to think that 

 by bringing together in proper conditions 

 the physical components of living things 

 and subjecting them to the action of vari- 

 ous forces, life might be generated anew 

 much as spontaneous combustion some- 

 times occurs in collections of inflammable 

 materials. This apparently not improb- 

 able surmise has led to speculations about 

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