THE WONDER OF LIFE 475 



Altogether, according to Roux, there are thirteen general 

 characters of living creatures, and we do not know of any 

 that he has omitted. Yet we venture to arrange the char- 

 acteristics somewhat differently. 



Down -breaking and Up -building. Every normal 

 organism is like a whirlpool in the river, always changing 

 and yet more or less remaining the same. It is like the 

 sunlit top of a fountain rising in the air ; its component 

 elements are restlessly changing on their way up or on 

 their way down. Like a clock it is always running down 

 and always needing to be wound up ; but unlike a clock 

 it can wind itself up. Not indefinitely, indeed, but some 

 of the Calif of nian Big Trees (Sequoia gigantea) did it, as we 

 have seen, for two thousand years genuine Methuselahs ! 

 The constructive, synthetic, up-building or winding- 

 up processes are summed up in the term Anabolism; 

 the destructive, analytic, down-breaking, running-down 

 processes are summed up in the term Katabolism, and both 

 are included in a term that covers both, Metabolism, for 

 which we have, unfortunately, no English equivalent no 

 word like the fine German word l Stofiwechsel ', change of 

 stuff. Chemical change is universal, of course, but the 

 peculiarity in the case of organisms is the balancing of 

 accounts, the correlation of up-building with down-break- 

 ing, of the winding-up with the running-down. That is 

 the criterion of vital processes, biologically considered, 

 that they go on of themselves, that they form part of a 

 concatenated series of chemical processes somehow bound 

 into unity, a series in which the pluses balance the minuses, 

 and the thing goes on. It is idle to try to express it in 

 terms of what goes on in the sterilized chemical laboratory, 

 for, taken as a whole, it is something more. Isolate any 



