CHAPTER VIII 

 Symbionticism and the Origin of Species 



When a variation develops in a living organism and this 

 deviation becomes hereditary, we recognize a new species 

 or a "new variety," depending upon the extent of the 

 variation. In the chapters on "Microsymbiosis" and 

 "An Analysis of Symbiont Reactions," a number of ex- 

 amples were given in which tissues and organs were shown 

 to originate as the result of the invasion of microorganisms, 

 or Symbionticism. The variations that were present in 

 these forms were of sufficient magnitude to constitute new 

 species. In the majority of these examples, it was possible 

 to recognize the essential cause of these variations by the 

 particularly prominent characteristics of the microsym- 

 bionts concerned. Various biological conditions and 

 phenomena, coupled with the bacterial nature of mito- 

 chondria and the responses of organisms to microbic inva- 

 sions, leads the author to conclude that Symbionticism is the 

 fundamental factor in the origin of species. While the 

 above mentioned evidence furnishes the basis for the hy- 

 pothesis, it is pertinent to test the theory further, and 

 attempt to determine how it articulates with other known 

 biological phenomena. 



If bacteria are the building stones, or the "primordial 

 stuff," from which all higher organisms have been con- 

 structed and modified, then we should be able to find in 

 bacteria the same metaboUc products that are found in 

 the specialized cells of the higher forms of life. The re- 

 searches that have been done on bacteria are so extensive 

 that it is beyond the realm of possibility for any one inves- 

 tigator to acquaint himself with the entire literature. The 



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