THE WONDER OF LIFE 475 



Altogether, according to Eoux, there are thirteen general 

 characters of hving 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 hke a whirlpool in the river, always changing 

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

 sunht 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 unHke a clock 

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

 of the Cahfornian 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 AnaboUsm; 

 the destructive, analytic, down-breaking, runmng-down 

 processes are summed up in the term Katdbolism, 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 ' StofEwechsel ', change of 

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

 pecuharity 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 imity, 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 



