THE WONDERS OF LIFE 



substance, plasm, and consists essentially in a circula- 

 tion of matter, or metabolism. At the same time 

 modern science has shown that the sharp distinction 

 formerly drawn between the organic and the inorganic 

 cannot be sustained, but that the two kingdom^ are 

 A profoundly and inseparably united. 



Of all the phenomena of inorganic nature with whiteh 

 the life-process may be compared, none is so much like 

 it externally and internally as the flame. This important 

 comparison was made two thousand four hundred years 

 ago by one of the greatest philosophers of the Ionic 

 school, Heraclitus of Ephesus — the same thinker who 

 first broached the idea of evolution in the two words, 

 Panta rei — all things are in a state of flux. Heracli- 

 V tus shrewdly conceived life as a fire, a real process of 

 .A. combustion, and so compared the organism to a torch. 



Max Verworn has lately employed this metaphor 

 with great effect in his admirable work on general 

 physiology, and has especially dealt with the comparison 

 of the individual life-form with the familiar butterfly 

 shape of the gas-flame. He says: 



The comparison of life to a flame is particularly siiitable for 

 helping us to realize the relation between form aiid metabolism. 

 The butterfly-shape of a gas-flame has a very characteristic 

 outline. At the base, immediately above the btuner, there 

 is still complete darkness; over this is a blue and faintly lumi- 

 nous zone; and over this again the bright flame expands on either 

 side like the wings of a butterfly. This peculiar form of the 

 flame, with its characteristic features, which are permanent, as 

 long as we do not interfere with the gas or the environment, is 

 solely due to the fact that the grouping of the molecules of the 

 gas and the oxygen at various parts of the flame is constant, 

 though the molecules themselves change every moment. At 

 the base of the flame the molecules of the gas are so thickly 

 pressed that the oxygen necessary for their combustion cannot 

 penetrate; hence the darkness we find here. In the bluish zone 

 a few molecules of oxygen have combined with the molecules 

 of the gas: we have a faint light as the result. But in the 



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