620 SCIENTIFIC THOUGHT. 



44. great difference which exists between dealing with a 



Difference in 



application vast number of lifeless and of living units. This 



to living and 



difference becomes evident if we consider that in the 

 former case the number of units is unalterable and 

 the units are indestructible; in the latter the elements 

 or units are subject to enormous increase and corre- 

 sponding destruction, generally with a preponderance of 

 the first. In the kinetic theory of gases we have to 

 consider, in every finite system, the conservation or 

 persistence of mass and motion, the two units we 

 deal with. To these two properties of an immensely 

 large crowd we have to reduce the various phenomena 

 of pressure, temperature, volume, available or unavail- 

 able energy. In the vast crowd of gemmules which 

 build up a new organism or regenerate an existing 

 one, we have to deal with a continual influx or 

 creation of new units and a continual extinction and 

 ejection of old or dead ones. Without venturing on 

 any theory as to how this state of things has come 

 about, we may see that the mathematics and statistics 

 of such crowds must be different from those referring 

 to stable, lifeless assemblages. The twofold task 

 arises of formulating the new problems and solving 

 them. To the extent that this is possible we shall 

 be able to deal mathematically with the great prob- 

 lem of variability; and for the practical application of 

 these mathematical formulae we shall have to collect 

 long series of facts and data of measurements the 

 material which has to be statistically arranged and 

 sifted, and which is to confirm the conclusions and 

 test the results which calculation has brought out. 



