SYMBIONTICISM 65 



It appears obvious that the end responses in life relation- 

 ships are not the fundamental cause for these associations, 

 but rather the chance outcome which is dependent upon 

 the physico-chemical properties and reactions of the sym- 

 bionts concerned. Certainly, one can not recognize a 

 display of choice in microorganisms which would lead them 

 to seek out certain hosts on account of advantageous quaU- 

 ties; nor can we recognize such properties in the host. The 

 cause for the development of a Hfe relationship is unrelated 

 to the responses accompanying the association. It is 

 these circmnstances that led the author to introduce the 

 term "prototaxis" to explain the "cause" for the develop- 

 ment of life relationships, and the term '^Symbionticism" 

 to designate the fundamental tendency and object of proto- 

 taxis. 



In attempting to explain the nature of the development 

 of symbiotic complexes, Meyer states: 



During an early period, the bacteria, fungi, etc., now found 

 as harmless entities within the insects, are probably parasites 

 producing pathologic conditions and disease. Acquired im- 

 munity later becomes inherited, and the microorganisms are 

 gradually gotten under control. The insects do not rid them- 

 selves of the invaders on account of the fact that transmission 

 from generation to generation is established with remarkable 

 precision. Still later, the invaders lost all of their harmful 

 effects, and since they secrete enzymes that prove serviceable to 

 the hosts, the conflict ends in mutual adaptation; just as in 

 plants (orchids and their mycorhizas) the symbiosis between the 

 tissues of the host and the microorganisms is a phenomenon of 

 parasitism, infection or disease, which has finally become essen- 

 tial to the existence of the animal. 



In a similar manner Cleveland ('26) suggests that "Such 

 structures as mycetocytes, bacteriocytes and mycetomes of 

 insects may be the survival of profound pathological 

 changes." 



