INDIVIDUALS AND SPECIES 33 



individuals, but those of most organisms exist only 

 as components of individuals. Individual honey- 

 bees may exist only as members of colonies. Col- 

 onies may be permanent, and may reproduce them- 

 selves as definitely as do individuals, yet they exist 

 only as parts of the species. In most species the 

 association is simpler: individuals exist only as 

 parts of species. In any case we have species only 

 through the existence of individuals. In such asso- 

 ciations it is useless to argue the relative impor- 

 tance of the various categories. They are different, 

 but interdependent. An individual cannot exist 

 without belonging to a species nor a species without 

 including individuals, and when two factors are 

 essential, neither can be said to surpass the other 

 in importance. Their importance, obviously, must 

 differ in kind, but evaluation of degree is not ad- 

 missible. 



Herein lies an important point of view for the 

 evolutionist. Species were long regarded as fixed 

 and invariable beyond certain limits. The idea of 

 organic evolution arose from the realization that 

 such was not the case, but that species were vari- 

 able to the extent of merging with each other, and 

 that they had undoubtedly arisen in the past by 

 development from preexisting species. This reali- 

 zation led even to denial of the importance of 

 species formation as a problem of evolution; one 

 writer, at least, has recognized evolution as a con- 



