CHAPTER V 



Symbionticism 



When a biological phenomenon has been observed and 

 the universahty of its occurrence has been estabhshed, it 

 is within the province of science to correlate it with other 

 biological processes. In attempting to analyze natural 

 processes and principles, it becomes apparent that our knowl- 

 edge has not advanced sufficiently so that it is possible to 

 make final analyses of natural phenomena, nor ascribe 

 absolute causes to biological activities; nevertheless, our 

 intellectual horizon is broadened if we can reduce a phe- 

 nomenon to the category of a principle. 



The universal presence of microorganisms within the 

 cells of all plants and animals, obviously, points to the 

 consummation of a biologic process or principle as funda- 

 mental in significance as that of reproduction. This 

 principle has been named "Symbionticism" by the author 

 (Wallin, '23). Just as sexual reproduction is dependent 

 upon other biological principles or factors (fertihzation, 

 cell division), so, also, Symbionticism is the end result of a 

 more primitive factor or principle. This more primitive 

 principle has been named "prototaxis" by the author and 

 has been defined as "the innate tendency of one organism 

 or cell to react in a definite manner to another organism or 

 cell." Prototaxis may be positive or negative. Negative 

 prototaxis is the repulsion of one organism or cell by an- 

 other. Negative prototaxis can lead to no permanent mani- 

 festation or alteration in an organism and consequently 

 it may not be readily detected. Positive prototaxis is the 

 affinity of one organism or cell for another organism or 



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