SYMBIONTICISM 59 



cell. This may result in various kinds of vital relationships. 

 These relationships have long been known and recognized 

 by the terms: conjugation, symplasm, cell fusion, parasi- 

 tism, and symbiosis. 



Prototaxis, on first analysis, may appear to be identical 

 and synonymous with "chemotaxis." It is possible that 

 chemotaxis is the essential force in prototaxis, but doubt- 

 less other forces play a role in the operation of the principle. 

 It would be quite impossible to analyze and enumerate the 

 factors that enter into prototaxis. It appears probable, 

 however, that such forces as surface tension, Hght, tem- 

 perature, moisture, and probably electrical potential are 

 involved in the process. Still other modifying factors 

 may be concerned in the operation of the principle. Our 

 present purpose, however, is not an analysis of the fac- 

 tors involved in prototaxis, but rather a record of its 

 occurrence. 



The more familiar expressions of positive prototaxis are 

 to be found in those Hfe relationships that are known as 

 parasitism and symbiosis. It is evident that these two 

 vital relationships are closely akin. The conceptions that 

 have developed in connection with these associations have 

 been based more or less upon the injurious or beneficial 

 results derived therefrom. These conceptions have also 

 involved the idea of purpose. The term "parasitism" 

 implies some benefit to the parasite with either a harmful 

 or indifferent response on the part of the host. Symbiosis 

 is apphed to those cases where mutual benefit is derived. 

 It is evident that there is no sharp distinction between 

 parasitism and symbiosis. Considered from the point 

 of view of prototaxis, parasitism and symbiosis are merely 

 different end responses in the expression of one and the 

 same biological principle. 



The following diagram may serve to clarify the relation- 



