16 CREATIVE EVOLUTION ichap. 



lar organism of the Infusorian, I find, even in this simple 

 cell, the same process of growing old. The Infusorian 

 is exhausted at the end of a certain number of divisions, 

 and though it may be possible, by modifying the environ- 

 ment, to put off the moment when a rejuvenation by con- 

 jugation becomes necessary, this cannot be indefinitely 

 postponed. 1 It is true that between these two extreme 

 cases, in which the organism is completely individualized, 

 there might be found a multitude of others in which the 

 individuality is less well marked, and in which, although 

 there is doubtless an ageing somewhere, one cannot say 

 exactly what it is that grows old. Once more, there is no 

 universal biological law which applies precisely and auto- 

 matically to every living thing. There are only directions 

 in which life throws out species in general. Each particular 

 species, in the very act by which it is constituted, affirms 

 its independence, follows its caprice, deviates more or 

 less from the straight line, sometimes even remounts the 

 slope and seems to turn its back on its original direction. 

 It is easy enough to argue that a tree never grows old, 

 since the tips of its branches are always equally young, 

 always equally capable of engendering new trees by budding. 

 But in such an organism — which is, after all, a society 

 rather than an individual — something ages, if only the 

 leaves and the interior of the trunk. And each cell, con- 

 sidered separately, evolves in a specific way. Wherever 

 anything lives, there is, open somewhere, a register in which 

 time is being inscribed. 



This, it will be said, is only a metaphor. — It is of the 

 very essence of mechanism, in fact, to consider as meta- 

 phorical every expression which attributes to time an 

 effective action and a reality of its own. In vain does 



1 Calkins, Studies on the Life History of Protozoa (Archiv f. Entwick- 

 lungsmechanik, vol. xv., 1903, pp. 139-186). 



