26 ESSAYS OF A BIOLOGIST 



first time in biological history there has been an 

 aggregation (in the technical biological sense) of 

 minds. Over and over again in evolution does the 

 process of aggregation appear."^ It is an advantage, 

 for at one jump it lands life on a new level of size, 

 with new possibilities of division of labour and spe- 

 cialization. It appears in the aggregation of Pro- 

 tozoa to form the colonial ancestor of all higher, 

 many-celled forms. It appears again on this new 

 level in the aggregation of hydroid polyps, of poly- 

 zoa, of ascidians, and especially in the beautiful float- 

 ing Siphonophora, in which the polyp-like units 

 (themselves historically aggregates of cells) have 

 become so subordinate in relation to the whole that 

 they can often scarcely be recognized as individuals, 

 and the individuality of the aggregate is much more 

 marked than that of its components. It appears in 

 a new way in the Termites and in the social Hy- 

 menoptera — ants, bees, and wasps. Here the bonds 

 uniting the members of the aggregate are not phys- 

 ical but mental, their sense-impressions and instincts; 

 but the principle is identical throughout. Finally in 

 man we have not merely aggregation of physical in- 

 dividuals held together by mental bonds, but aggre- 

 gation of minds as well as of physical individuals. 



In many mammals and birds, each generation can 

 extend its influence on to the next, and the experi- 

 ence of the parents is in part made available to the 

 offspring. But never until the origin of speech was 



^Huxley, '12. 



