592 DISHARMONIES AND OTHER SHADOWS 



The clearest statement of the problem has been given 

 by Prof. C. M. Child in his Senescence and Rejuvenes- 

 cence. The process of progressive differentiation or com- 

 plexifying involves the accumulation of relatively inactive 

 constituents in the living matter. It becomes necessary to 

 have stable frameworks, and it is difficult to keep these 

 young. The vital current deposits materials in its flow, 

 and the bed begins to slow the stream. There are always 

 processes of rejuvenescence at work, removing the relatively 

 inactive material, and re-accelerating the rate so that fresh 

 erosion occurs. All sorts of devices are resorted to, which 

 secure rejuvenescence; many of them are very drastic, such 

 as periodically breaking the body to bits and beginning 

 afresh; but the tendency is for rejuvenescence to lag in the 

 higher animals and for senescence to win. It cannot be 

 otherwise. Death was the price paid for a body; senescence 

 is the tax on specialisation. In the very simple organisms 

 the stable mortal parts of the colloidal substratum, which 

 is life's laboratory, can be reduced and restored piecemeal, 

 and the creature never grows old. Perhaps the same is true of 

 the fresh-water polyp, which thus will have, besides its indif- 

 ference to wounds, another reason for being called Hydra. 

 But as life became more worth living, and the organism 

 more of an agent, the capacity for rejuvenescence was 

 limited. Thus, as Professor Child tells us, " For his high 

 degree of individuation man pays the penalty of individual 

 death, and the conditions and processes in the human or- 

 ganism which lead to death in the end are the conditions 

 and processes which make man what he is." Thus one 

 may perhaps say without irreverence that science has made 

 the shadow of death more intelligible. 



What have we, then? At the foot of the scale there are 



