722 



ECOLOGY AND EVOLUTION 



son, 1939a). The arrows indicate the di- 

 rection of the effect and are double- 

 pointed if there is a reciprocal inter- 

 action between the factors. Organisms 

 are boxed to distinguish them from other 

 factors. Theoretically, each arrow could be 

 evaluated quantitatively in terms of direct 



factors. Population growth and regular or 

 irregular periodic fluctuations would pro- 

 duce quantitative variations in the influence 

 of so many factors that such a static dia- 

 gram is hardly more than a single frame in 

 a long motion picture of ontogenetic and 

 phylogenetic processes. Even with all the 



FLUCTUATING 



Fig. 261. Diagram of the factoral complex influencing the population of a typical termite of 



the family Rhinotermitidae. Arrows indicate the direction of the effect. 



or indirect eflFect upon the biocoenose. Dia- 

 grams illustrating even closely related asso- 

 ciations would show striking qualitative 

 and quantitative differences among popula- 

 tion factors, differences that could often 

 be arranged in an evolutionary order. The 

 majority of these would probably be varia- 

 tions in the degree of influence of certain 



knowledge so far gained concerning any 

 given biocoenose, this single frame is doubt- 

 less a gross oversimplification. Complete 

 knowledge will never be obtained, but the 

 slow process of establishing tiny relation- 

 ships between the parts of this immense 

 whole is both fascinating and highly val- 

 uable to mankind. 



