SOCIAL EVOLUTION AS A BIOLOGICAL PROCESS 265 



second kind originates from the first, and how in its turn 

 this grows in time into the third and most complex 

 association ; thus Vorticella and Volvox connect Amceba 

 with the cell-community individual Hke Hydra and a 

 sohtary wasp, while the annually established colonies 

 of social wasps and of bumblebees lead to the permanent 

 colony-individual. Restricting attention to the three 

 primary examples, ,and remembering tliat the criterion 

 of completeness is the ability to discharge satisfactorily 

 all of the eight biological tasks, it is clear that the entire 

 Hydra and the whole ant-cornmunity correspond physio- 

 logically with Amoeba, although the first-named is 

 structurally a cell-community equivalent to many pro- 

 tozoa, and the insect colony is composed of many such 

 cell-communities as elements. In the third type, 

 neither a single queen nor a single worker is able to 

 carry on all of the biological tasks any more than a 

 muscle-cell or an unformed egg of Hydra can maintain 

 itself capably in isolation. Therefore the ant-society 

 as a whole and the Hydra in its entirety are organic 

 individuals on the same physiological plane with 

 Amoeba, and they are equally subject to the same great 

 laws of nature demanding selfish maintenance and ra- 

 cial perpetuation. 



But we must not lose sight of the fundamental value 

 of the unit during the evolution of a higher from a lower 

 type. The tissue-cell of Hydra must still obey the 

 mandate to live an efficient personal life, because this 

 is necessary for the welfare of other cells and of the 

 whole complex. The original egoistic tasks are not 

 abolished, but new duties are added to them in ways 

 we have learned to distinguish. In Vorticella the 



