Volume 1. Number 17. 



REVIEW OF THE GENUS GENNAEUS 



By C. WILLIAM BEEBE, 



Curator of Birds. 



Part I. 



Evolution as a phenomenon is beyond dispute. The exact 

 methods of evolution are only partly clear. We have so far 

 failed to discern many of the ways and means by which the 

 organisms of our day have acquired their adaptations, have 

 differentiated their tissues, or have survived the competition 

 of past generations. One thing is certain : no single theory will 

 suffice to account for the evolution of life in general, nor even 

 for a single organ of any individual. If careful study of the 

 subject has taught us nothing else, it has constrained us to 

 believe in multiple causes; in an eternal plexus of actions and 

 reactions. And it is as impossible to believe that any one char- 

 acter subserves only a single function throughout the life of an 

 individual, as that its inception in past time — whether gradual 

 or sudden — and its development, was brought about solely by 

 the action of any isolated factor. 



I wish that every worker along the lines of evolutionary 

 research would pin to his desk, place in his watch or strive 

 always to keep vividly in both conscious and subconscious 

 thought some such symbol of the eternal interaction of factors 

 as Prof. Henry F. Osborn has given us.^ 



Heredity 

 Ontogeny 

 Environment 

 Selection 



With such a "wheel of life," both controlling and stimulat- 

 ing, there would be less swinging of the pendulum to extremes, 



1 Science. XXVII. 1908, p. 14; and Jour. Acad. Nat. Sci. Pliila. XV. 1912, 

 p. 298. 



