SYMBIONTICISM AND ORGANIC EVOLUTION 147 



pies: Symbionticism, the fundamental principle control- 

 ling the origin of species; Natural Selection, the chief prin- 

 ciple controlling the retention and destruction of formed 

 species; and an unkno^^m principle responsible for progres- 

 sive evolution. It appears evident that the three princi- 

 ples are closely intertwined or associated in the control 

 of organic evolution; one principle, apparently, can not 

 exist independent of the other two. It might appear that 

 "progressive evolution" is but the result of the combined 

 operations of Symbionticism and Natural Selection. When 

 one reflects on the more or less gradual morphologic and 

 physiologic perfection of Uving organisms leading up to 

 man, it is difficult to conceive of this progressive evolution 

 having been directed by Symbionticism and Natural Selec- 

 tion alone. While it is just as impossible to conceive of 

 the nature of this unknown principle in the absence of data 

 as it was to visuahze Symbionticism before the data ac- 

 cumulated, nevertheless, it appears to the author that a 

 distinct factor or set of factors control progressive evolution. 

 Organic evolution may be likened to a mammoth, creep- 

 ing, kaleidoscopic procession which began to move when 

 life first appeared upon the earth. In the beginning the 

 procession was small. With the passing eons of time, 

 there has been an ever increasing multitude, slowly, but 

 steadily, moving forward. New forms have constantly 

 joined the procession, and old forms have dropped out. 

 We have not been able to look back into the distant past 

 and learn from whence the procession started; we are not 

 able to look forward into the future and predict where the 

 procession means to go; we are only trying to analyze and 

 determine the nature of the factors responsible for the 

 kaleidoscopic nature of the procession as it appears today. 



