440 SCIENTIFIC THOUGHT. 



the chemical laboratory by processes which were like 

 or unlike those going on in the organism itself. But 

 such stable compounds are not the bearers, they are 

 merely the collateral products, the accompaniments, of 

 the living process. The artificial production of organic 

 compounds, beginning with Wohler's production of urea, 

 and ending with the production of albumen, do not 

 approach the problem of the production of living matter. 

 Could the chemist produce protoplasm, it would not be 

 living ; or were he fortunate enough to hit upon one of 

 its many metamorphoses, it would die the next moment, 

 not having the inner structure or the external and 

 internal environment necessary for its self-conservation 

 and activity. Nor do we seem to get any nearer the 

 real secret by analysing more closely the chemical and 

 physical changes, the metabolism, the rhythmical processes 

 which constitute this activity. We call it nutrition or 

 respiration, assimilation and disassimilation, oxidation and 

 reduction storing up and letting loose of energy. We 

 picture to ourselves the building up of more and more 

 complicated chemical molecules, containing thousands of 

 atoms, in a temporary and easily disturbed equilibrium, 

 and the subsequent breaking down again of these complex 

 structures by gradual decomposition or by sudden explo- 

 sions due to external stimuli, or by the still more mysteri- 

 ous directive action of conscious will : we liken them to 

 the pulling of a trigger, or the gathering up and letting 

 loose of a destructive avalanche by the motion of a flake of 

 snow on the top of a peak. We see how this metabolism, 

 this " Stoff- und Kraft- wechsel," goes on in the smallest 

 amoeba in rhythmical movements, and how, in higher 



