i] ORGANIZED BODIES 13 



geometrician is too ready to take advantage here of our 

 inability to give a precise and general definition of in- 

 dividuality. A perfect definition applies only to a com- 

 pleted reality; now, vital properties are never entirely 

 realized, though always on the way to become so; they 

 are not so much states as tendencies. And a tendency 

 achieves all that it aims at only if it is not thwarted by 

 another tendency. How, then, could this occur in the 

 domain of life, where, as we shall show, the interaction 

 of antagonistic tendencies is always implied? In particu- 

 lar, it may be said of individuality that, while the ten- 

 dency to individuate is everywhere present in the organized 

 world, it is everywhere opposed by the tendency towards 

 reproduction. For the individuality to be perfect, it 

 would be necessary that no detached part of the organism 

 could live separately. But then reproduction would be 

 impossible. For what is reproduction, but the building 

 up of a new organism with a detached fragment of the old? 

 Individuality therefore harbors its enemy at home. Its 

 very need of perpetuating itself in time condemns it never 

 to be complete in space. The biologist must take due 

 account of both tendencies in every instance, and it is 

 therefore useless to ask him for a definition of individuality 

 that shall fit all cases and work automatically. 



But too often one reasons about the things of life in 

 the same way as about the conditions of crude matter. 

 Nowhere is the confusion so evident as in discussions about 

 individuality. We are shown the stumps of a Lum- 

 briculus, each regenerating its head and living thence- 

 forward as an independent individual; a hydra whose 

 pieces become so many fresh hydras; a sea-urchin's egg 

 whose fragments develop complete embryos: where then, 

 we are asked, was the individuality of the egg, the hydra, 

 the worm? — But, because there are several individuals 



